HK1147623B - Interference management utilizing power and attenuation profiles - Google Patents

Description

Interference management using power and attenuation curves

Claiming priority based on 35U.S.C. § 119

This application claims the benefit and priority of the following commonly owned patent applications: U.S. provisional patent application No.60/974,428, filed on 21/9/2007, assigned attorney docket No. 071700P 1; U.S. provisional patent application No.60/974,449, filed on 21/9/2007, assigned attorney docket No. 071700P 2; U.S. provisional patent application No.60/974,794, filed 24/9/2007, assigned attorney docket No. 071700P 3; and U.S. provisional patent application No.60/977,294, filed on 3/10/2007, assigned attorney docket No. 071700P4, the disclosure of each of which is incorporated herein by reference.

Technical Field

The present application relates generally to wireless communications and more particularly, but not exclusively, to improving communication performance.

Background

Wireless communication systems are widely deployed to provide various types of communication (e.g., voice, data, multimedia services, etc.) to multiple users. With the rapidly growing demand for high-rate and multimedia data services, there is a challenge to implement efficient and robust communication systems with enhanced performance.

To supplement conventional mobile phone network base stations, small coverage base stations may be deployed (e.g., installed in a user's home) to provide more robust indoor wireless coverage to mobile units. Such small-coverage nodes are generally referred to as access point base stations, home node bs, or femtocells. Typically, such small coverage base stations are connected to the internet and the mobile operator's network via a DSL router or a cable modem.

RF interference problems may arise because mobile operators may not optimize the radio frequency ("RF") coverage of small coverage base stations and the deployment of such base stations may be ad-hoc (ad-hoc). Also, for small coverage base stations, soft handoff may not be supported. Accordingly, there is a need for improved interference management for wireless networks.

Disclosure of Invention

The following is a summary of example aspects of the disclosure. It should be understood that any reference herein to the term "aspect" may refer to one or more aspects of the present disclosure.

The present disclosure relates in some aspects to managing interference by using fractional reuse techniques. For example, in some aspects, fractional reuse may comprise: a portion of a set of hybrid automatic repeat request ("HARQ") interlaces allocated for uplink traffic or downlink traffic is used. In some aspects, fractional reuse may comprise: a portion of the time slot allocated for uplink traffic or downlink traffic is used. In some aspects, fractional reuse may comprise: a portion of the spectrum allocated for uplink traffic or downlink traffic is used. In some aspects, fractional reuse may comprise: a portion of a set of spreading codes (e.g., SF16) allocated for uplink traffic or downlink traffic is used. In some aspects, such portions may be defined or allocated such that neighboring nodes use non-overlapping resources. In some aspects, the definition and allocation of such portions may be based on interference-related feedback.

The present disclosure relates in some aspects to managing interference through the use of power management related techniques. For example, in some aspects, transmit power of an access terminal may be controlled to mitigate interference at non-associated access points. In some aspects, noise factors or receive attenuation of an access point are controlled based on received signal strength associated with signals from one or more access terminals.

The present disclosure relates in some aspects to managing interference through the use of transmit power curves and/or attenuation curves. For example, downlink transmit power or uplink receiver extension may be dynamically changed at a node as a function of time. Here, different nodes may use different phases of the curve to mitigate interference between nodes. In some aspects, the curve may be defined in terms of interference-related feedback.

Drawings

These and other exemplary aspects of the present disclosure are described in the detailed description, appended claims, and accompanying drawings, in which:

FIG. 1 is a simplified block diagram of several exemplary aspects of a communication system;

FIG. 2 is a simplified block diagram illustrating several exemplary aspects of components in an example communication system;

FIG. 3 is a flow diagram of several example aspects of operations that may be performed to manage interference;

fig. 4 is a flow diagram of several example aspects of operations that may be performed to manage interference using HARQ interlace-based fractional reuse;

fig. 5 is a flow diagram of several example aspects of operations that may be performed to manage interference using a transmit power curve;

FIG. 6 is a simplified diagram illustrating several aspects of an example transmit power curve;

fig. 7 is a flow diagram of several example aspects of operations that may be performed to manage interference using a receive attenuation curve;

FIG. 8 is a simplified diagram illustrating several aspects of an example receive attenuation curve;

fig. 9 and 10 are flow diagrams of several example aspects of operations that may be performed to manage interference using slot-based fractional reuse;

fig. 11 and 12 are flow diagrams of several example aspects of operations that may be performed to manage interference using spectrum-based fractional reuse;

fig. 13 and 14 are flow diagrams of several example aspects of operations that may be performed to manage interference using spreading code based fractional reuse;

fig. 15 is a flow diagram of several example aspects of operations that may be performed to manage interference using transmit power control;

FIG. 16 is a simplified diagram illustrating several aspects of an example power control function;

fig. 17 is a flow diagram of several example aspects of operations that may be performed to manage interference by dynamically adjusting attenuation factors;

fig. 18 is a simplified diagram of a wireless communication system;

fig. 19 is a simplified diagram of a wireless communication system including a femto node;

fig. 20 is a simplified diagram illustrating a coverage area for wireless communication;

FIG. 21 is a simplified block diagram of several exemplary aspects of a communications component;

fig. 22-30 are simplified block diagrams of several example aspects of an apparatus configured to manage interference as taught herein.

In accordance with common practice, the various features shown in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the drawings may be simplified for clarity. Accordingly, the drawings may not depict all of the components of a given apparatus (e.g., device) or method. Finally, the same reference numerals may be used throughout the specification and drawings to refer to the same features.

Detailed Description

Various aspects of the disclosure are described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative. One skilled in the art will appreciate from the teachings herein that one aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. Furthermore, an aspect may comprise at least one element of a claim.

Fig. 1 illustrates an example aspect of a communication system 1000 in which distributed nodes (e.g., access points 102, 104, and 106) provide wireless connectivity to other nodes (e.g., access terminals 108, 110, and 112) that may be installed in, or may roam through, associated geographic regions. In some aspects, access points 102, 104, and 106 may communicate with one or more network nodes (e.g., a centralized network controller, such as network node 114) to facilitate wide area network connectivity.

Access points such as access point 104 may be restricted such that only certain access terminals (e.g., access terminal 110) are allowed to access the access point, or the access point may be restricted in some other manner. In this case, the restricted access point and/or its associated access terminals (e.g., access terminal 110) may interfere with other nodes in system 100, such as: an unrestricted access point (e.g., macro access point 102), an associated access terminal of the unrestricted access point (e.g., access terminal 108), another restricted access point (e.g., access point 106), or an associated access terminal of the another restricted access point (e.g., access terminal 112). For example, the access point closest to a given access terminal may not be the serving access point for that access terminal. Thus, transmissions by the access terminal may interfere with reception at the access terminal. As discussed herein, fractional reuse, power control, and other techniques may be used to mitigate interference.

Example operations of a system, such as system 100, will be discussed in more detail in conjunction with the flow diagram of fig. 2. For convenience, the operations of fig. 2 (or any other operations discussed or taught herein) may be described as being performed by specific components (e.g., components of system 100 and/or components of system 300 as shown in fig. 3). However, it should be understood that these operations may be performed by other types of components, and may be performed using a different number of components. It should also be appreciated that one or more of the operations described herein may not be used in a given implementation.

For purposes of illustration, various aspects of the disclosure will be described in the context of a network node, an access point, and an access terminal communicating with each other. However, it should be understood that the teachings herein may be applied to other types of devices or devices that are referred to using other terminology.

Fig. 3 illustrates several example components that may be incorporated into a network node 114 (e.g., a radio network controller), an access point 104, and an access terminal 110 in accordance with the teachings herein. It should be understood that the components shown for a given one of these nodes may also be incorporated into other nodes in the system 100.

Network node 114, access point 104, and access terminal 110 include transceivers 302, 304, and 306, respectively, for communicating with each other and with other nodes. The transceiver 302 includes: a transmitter 308 for transmitting a signal; and a receiver 310 for receiving the signal. The transceiver 304 includes: a transmitter 312 for transmitting a signal; and a receiver 314 for receiving the signal. The transceiver 306 includes: a transmitter 316 for transmitting a signal; and a receiver 318 for receiving the signal.

In a typical implementation, the access point 104 communicates with the access terminal 110 via one or more wireless communication links, and the access point 104 communicates with the network node 114 via a backhaul. It should be appreciated that wireless or non-wireless links may be used between these nodes or other nodes in various implementations. Thus, transceivers 302, 304, and 306 may include wireless and/or non-wireless communication components.

Network node 114, access point 104, and access terminal 110 also include various other components that may be used in conjunction with interference management as taught herein. For example, network node 114, access point 104, and access terminal 110 may include interference controllers 320, 322, and 324, respectively, for mitigating interference, and for providing other related functionality as taught herein. Interference controllers 320, 322, and 324 may include one or more components for performing certain types of interference management. Network node 114, access point 104, and access terminal 110 may include communication controllers 326, 328, and 330, respectively, for managing communications with other nodes and for providing other related functionality as taught herein. Network node 114, access point 104, and access terminal 110 may include timing controllers 332, 334, and 336, respectively, for managing communications with other nodes and for providing other related functionality as taught herein. Other components shown in fig. 3 will be discussed in the disclosure that follows.

For purposes of illustration, interference controllers 320 and 322 are depicted as including several controller components. In practice, however, a given implementation may not use all of these components. Here, the HARQ controller component 338 or 340 may provide functionality related to HARQ interlace operations as taught herein. The profile controller component 342 or 344 may provide functionality related to transmit power profile or receive attenuation operations as taught herein. The slot controller component 346 or 348 may provide functionality related to the slot portion operations taught herein. The spectral mask controller component 350 or 352 may provide functionality related to the spectral mask operations taught herein. Spreading code controller component 354 or 356 may provide functionality related to spreading code operations as taught herein. The transmit power controller component 358 or 360 may provide functionality relating to transmit power operation as taught herein. The attenuation factor controller component 362 or 364 may provide functionality related to the attenuation factor operation taught herein.

Fig. 2 illustrates how network node 114, access point 104, and access terminal 110 may interact with each other to provide interference management (e.g., interference mitigation). In some aspects, these operations may be employed on the uplink and/or downlink to mitigate interference. In general, one or more of the techniques described by fig. 2 may be employed in more specific implementations described below in conjunction with fig. 4-18. Thus, for the sake of clarity, the description of the more specific implementations may not describe these techniques in detail.

As shown at block 202, the network node 114 (e.g., interference controller 320) may optionally define one or more interference management parameters for the access point 104 and/or the access terminal 110. Such parameters may take various forms. For example, in some implementations, network node 114 may define a fractional reuse parameter for mitigating interference on the uplink and/or downlink. As described herein, such fractional reuse may involve one or more of HARQ interleaving, puncturing (puncturing), spectrum, or spreading codes. In some implementations, the network node 114 may define other types of interference management information, such as transmit power parameters and receive attenuation parameters. Examples of such parameters are described in more detail below in conjunction with fig. 4-18.

In some aspects, the definition of the interference parameter may include determining how to allocate one or more resources. For example, the operations of block 402 may include defining how the allocated resources (e.g., spectrum, etc.) may be partitioned for fractional reuse. In addition, the definition of the fractional reuse parameter may include determining how much of the allocated resources (e.g., how many HARQ interlaces, etc.) may be used by any one of a set of access points (e.g., restricted access points). The definition of the fractional reuse parameter may also include determining how much resources a set of access points (e.g., restricted access points) may use.

In some aspects, the network node 114 may define the parameters according to received information indicating whether interference is possible on the uplink or downlink, and the extent of the interference, if any. Such information can be received in various manners from various nodes (e.g., access points and/or access terminals) in the system (e.g., over a backhaul, over the air, etc.).

For example, in some cases, one or more access points (e.g., access point 104) may monitor the uplink and/or downlink and send an indication of the detected interference on the uplink and/or downlink to network node 114. As an example of the former case, the access point 104 may calculate the signal strength of signals it receives from nearby access terminals (e.g., access terminals 108 and 112) that it is not associated with (e.g., is not served by) and report it to the network node 114.

In some cases, for each access point in the system, a load indication may be generated when they are experiencing a higher load. Such an indication may take the form of, for example, a busy bit in 1xEV-DO, a relative grant channel ("RGCH") in 3GPP, or some other suitable form. In a conventional scenario, an access point may send this information to its associated access terminals via a downlink. However, such information may also be sent to network node 114 (e.g., via a backhaul).

In some cases, one or more access terminals (e.g., access terminal 110) may monitor for downlink signals and provide information based on this monitoring. Access terminal 110 may send such information to access point 104 (e.g., access point 104 may forward the information to network node 114) or network node 114 (via access point 104). Other access terminals in the system may send information to the network node 114 in a similar manner.

In some cases, access terminal 110 may generate measurement reports (e.g., on a repeated basis). In some aspects, such measurement reports may indicate from which access points access terminal 110 is receiving signals, a received signal strength indication (e.g., Ec/lo) associated with signals from each access point, a path loss to each access point, or some other appropriate type of information. In some cases, the measurement report may include information related to any load indications received by access terminal 110 via the downlink.

Network node 114 may then use information from one or more measurement reports to determine whether access point 104 and/or access terminal 110 are in closer proximity to another node (e.g., another access point or access terminal). In addition, the network node 114 may use this information to determine whether any of these nodes interfere with any other of these nodes. For example, the network node 114 may determine the received signal strength at a node based on the transmit power of the node transmitting the signal and the path loss between the nodes.

In some cases, access terminal 110 may generate information indicating a signal-to-noise ratio (e.g., signal-to-interference-and-noise ratio, SINR) on the downlink. Such information may include, for example, a channel quality indication ("CQI"), a data rate control ("DRC") indication, or some other suitable information. In some cases, this information may be sent to the access point 104, and the access point 104 may forward this information to the network node 114 for interference management operations. In some aspects, the network node 114 may use such information to determine whether there is interference on the downlink or whether interference in the downlink is increasing or decreasing.

As described in more detail below, in some cases, the interference-related information may be used to determine how to deploy partial reuse to mitigate interference. As one example, CQI or other suitable information may be received on a per HARQ interlace basis, from which it may be determined which HARQ interlaces are associated with the lowest interference level. Similar techniques may be used for other fractional reuse techniques.

It should be appreciated that the network node 114 may define the parameters in various other ways. For example, in some cases, network node 114 may arbitrarily select one or more parameters.

As shown at block 204, the network node 114 (e.g., the communication controller 326) transmits the defined interference management parameters to the access point 104. As described below, in some cases, the access point 104 uses these parameters, and in some cases, the access point 104 forwards these parameters to the access terminal 110.

In some cases, network node 114 may manage interference in the system by defining interference management parameters to be used by two or more nodes (e.g., access points and/or access terminals) in the system. For example, in the case of a fractional reuse scheme, network node 114 may send different (e.g., mutually exclusive) interference management parameters to neighboring access points (e.g., access points that are close enough to potentially interfere with each other). As a specific example, the network node 114 may allocate a first HARQ interlace to the access point 104 and a second HARQ interlace to the access point 106. In this manner, communications at one restricted access point may not substantially interfere with communications at another restricted access point. Similar techniques may be used for other fractional reuse schemes and for access terminals in the system.

As shown at block 206, the access point 104 (e.g., interference controller 322) determines interference management parameters that it may use or interference management parameters that may be transmitted to the access terminal 110. Where the network node 114 defines interference management parameters for the access point 104, this determination may simply involve receiving the specified parameters and/or retrieving the specified parameters (e.g., from a data store).

In some cases, the access point 104 determines the interference management parameters on its own. These parameters may be similar to the parameters discussed above in connection with block 202. Additionally, in some cases, these parameters may be determined in a manner similar to that discussed above at block 202. For example, access point 104 may receive information (e.g., measurement reports, CQI, DRC) from access terminal 110. In addition, the access point 104 may monitor the uplink and/or downlink to determine interference on such links. The parameters may also be arbitrarily selected by the access point 104.

In some cases, the access point 104 may cooperate with one or more other access points to determine interference management parameters. For example, in some cases, the access point 104 may communicate with the access point 106 to determine which parameters are being used by the access point 106 (thereby selecting different parameters) or to negotiate the use of different (e.g., mutually exclusive) parameters. In some cases, the access point 104 may determine (e.g., from CQI feedback indicating that another node is using resources) whether it may interfere with the other node, and if so, define its interference management parameters to mitigate such possible interference.

As shown at block 208, the access point 104 (e.g., the communication controller 328) may send interference management parameters or other related information to the access terminal 110. For example, in some cases, such information may indicate how to deploy fractional reuse (e.g., which HARQ interlaces to use, which spectral masks to use, etc.) on the uplink or downlink between the access point 104 and the access terminal 110. In some cases, this information may relate to power control (e.g., specifying uplink transmit power).

Access point 104 may therefore transmit on the downlink to access terminal 110, or access terminal 110 may transmit on the uplink to access point 104, as shown at blocks 210 and 212. Here, the access point 104 may use its interference management parameters to transmit on the downlink and/or receive on the uplink. Similarly, access terminal 110 may consider these interference management parameters when receiving on the downlink or transmitting on the uplink.

In some implementations, access terminal 110 (e.g., interference controller 306) may define one or more interference management parameters. Such parameters may be used by access terminal 110 and/or transmitted (e.g., by communication controller 330) to access point 104 (e.g., for use during uplink operation).

Referring now to fig. 4, operations related to the use of a fractional reuse scheme that uses HARQ interlaces on the uplink or downlink will be described in more detail. In some aspects, system 100 may use time division multiplexing, whereby information may be transmitted over one or more defined time slots. Such time slots may take various forms and/or be referred to using various terms. As an example, in various implementations, a slot may relate to or be referred to as a frame, a subframe, a gap, a transmission time interval ("TTI"), a HARQ interlace, and so on. By way of example, a predetermined number of time slots (e.g., TTIs) 1-16 may be monitored and used for downlink transmissions. A similar scheme may be used for uplink transmission.

Depending on the traffic and associated interference levels on the monitored slots, and depending on the application of one or more of the schemes taught herein, uplink or downlink transmissions may be limited to a defined number of slots N, which is less than the total number of slots M, where, for example, N-8 and M-16. In some aspects, such a fractional reuse scheme may use HARQ interlaces.

In a conventional 1xEV-DO system, each HARQ process may be allocated, for example, every fourth subframe, so that HARQ retransmission of an original transmission in subframe "n" is performed in slots (n +4), (n +8), (n +12), and so on. As a specific example, HARQ interlace 1 may be allocated subframes 1, 5, and 9, etc. In the event that the original data transmission for HARQ interlace 1 during subframe 1 was unsuccessful, a negative acknowledgement ("NACK") signal may be sent on the reverse link (e.g., uplink in the case of downlink HARQ transmissions). The data may then be retransmitted during subframe 5 of the same HARQ interlace 1, and an acknowledgement ("ACK") signal received (e.g., via the uplink) after a successful transmission. Similar operations may be performed on other HARQ interlaces 2, 3 and 4 by other HARQ processes.

In some aspects, a fractional reuse scheme may use HARQ interlaces to configure neighboring nodes (e.g., access points and/or access terminals) to transmit at different times. For example, a first access point may transmit during HARQ interlaces 1 and 2, while a second access point transmits during HARQ interlaces 3 and 4. As a result, interference between nodes that would otherwise occur can be reduced.

As shown at block 402 of fig. 4, the network node 114 (e.g., the HARQ control component 338 of the interference controller 320) determines how many HARQ interlaces each access point (e.g., an access point in a restricted set of access points) may use. For example, a defined number "N" of HARQ interlaces, which is less than a total number "M" of HARQ interlaces allocated for the group (e.g., as discussed above in connection with fig. 2), can be determined from interference-related feedback from one or more access points and/or access terminals in the system. Thus, at any given time, the number N of downlink (or uplink) HARQ interlaces in the total number M of HARQ interlaces may be defined in terms of the downlink (or uplink) behavior of the neighboring node over the M HARQ interlaces.

N may be a fixed value or defined dynamically. In the case where M is 4, the minimum value N may be greater than 0_MINAnd a maximum value N of less than 4_MAXN is set dynamically. In some cases, the value N may be arbitrarily determined. In general, however, the value N may be selected in an attempt to more effectively mitigate interference between nodes in the system. The determination of the value N may be based on different criteria.

For example, one criterion may relate to how the access points are deployed in the system (e.g., total number of access points, density of access points in a given area, relative proximity of access points, etc.). Here, if there are a large number of nodes close to each other, a small value of N may be used so that it is unlikely that neighboring nodes use the same HARQ interlace. Conversely, if there are a small number of nodes in the system, a larger value of N may be defined to improve communication performance (e.g., throughput).

Another criterion may relate to the traffic handled by the access point (e.g., amount of traffic, type of traffic, quality of service requirements of the traffic). For example, some types of traffic may be more susceptible to interference than other types of traffic. In this case, a smaller value of N may be used. In addition, some types of traffic may have more stringent throughput requirements (but less sensitive to interference), and thus, larger values of N may be used.

In some cases, network node 114 may define value N according to the received interference related information (e.g., as described in fig. 2). For example, the number of access points heard by a given access terminal and the relative proximity of the access points to the access terminal may be determined from measurement reports received from the access terminal. In this manner, the network node 114 may determine whether transmissions at a given cell (e.g., by a restricted access point or access terminal associated therewith) are likely to interfere with neighboring cells, and thus define N.

Network node 114 may also define N based on interference information received from one or more access points (e.g., as described in fig. 2). For example, if the interference value is high, a lower value of N may be defined. In this way, the number of HARQ interlaces used by a given access point may be reduced, thereby reducing the likelihood of interference on each set of N HARQ interlaces in the total number M of HARQ interlaces.

As shown at block 404, in some cases, network node 114 may specify a particular HARQ interlace to be used by a particular access point. For example, network node 114 may determine the amount of interference a given access point may see on each of the M HARQ interlaces and assign that access point a HARQ interlace with lower interference. As a specific example, network node 114 may determine that downlink transmissions by access point 106 on the two HARQ interlaces it is using (e.g., interlaces 3 and 4) may interfere with reception at the access terminal associated with access point 104. This may be determined, for example, from downlink interference related information that may be obtained by a network node as described herein. Network node 114 may then designate HARQ interlaces 1 and 2 for use by access point 104.

As described above, the determination of interference on each HARQ interlace may be based on signals received by network node 114. For example, the likelihood of interference between nodes may be determined from one or more measurement reports received from one or more access terminals as described herein. Additionally, for the downlink, an access terminal in the system may generate channel quality indication ("CQI") or data rate control ("DRC") information for each HARQ interlace (e.g., for each TTI in 3GPP) and forward such information to the network node 114. Also, for the downlink, the access terminal may monitor the downlink and provide interference related information on a per HARQ interlace (e.g., per TTI) basis. Similarly, for the uplink, the access terminal can monitor the uplink and provide interference-related information on a per HARQ interlace (e.g., per TTI) basis. In some cases (e.g., DRC feedback in 3GPP 2), the feedback from the access terminal may not provide the resolution of each HARQ interlace. In this case, ACK/NACK feedback or some other type of feedback may be used to identify the desired set of HARQ interlaces. As another example, the downlink data rate can be adjusted on a given HARQ interlace to determine a rate at which the access terminal can successfully decode data (e.g., with a given accuracy). From the best data rate determined for each HARQ interlace, it can be assumed which HARQ interlace will provide the best performance for a given access point. Alternatively, a centralized HARQ interlace selection scheme may be used (e.g., when a network node specifies HARQ interlaces for neighboring nodes, as described herein).

In some aspects, the designation of a particular HARQ interlace by network node 114 may depend on whether the corresponding uplink or downlink traffic is synchronous. Such synchronization may be achieved, for example, using an adjustment such as the Tau-DPCH (where the DPCH involves a dedicated physical channel) or some other suitable synchronization scheme.

In some aspects, network node 114 may specify consecutive HARQ interlaces for a given access point. In this way, at least a portion of the designated HARQ interlaces may not be interfered with without synchronizing uplink or downlink traffic for different nodes. As an example, if HARQ interlaces 1-4 are allocated to a first access point and HARQ interlaces 5-8 are allocated to a second access point, then these access points will not experience interference from another access point on at least three HARQ interlaces, even if the timing of these access points is not synchronized.

The network node 114 then transmits its defined HARQ interlace parameters to one or more access points, as shown at block 406. For example, the network node 114 may send a node-specific designation to each access point, or the network node 114 may send a common designation to all access points in a group of access points.

As shown at block 408, the access point 104 (e.g., the HARQ control component 340 of the interference controller 322) determines the HARQ interlace it will use for uplink or downlink communications. Here, the access point 104 has received the value N from the network node 114. In the case where the network node 114 specifies HARQ interlaces to be used by the access point 104, the access point 104 may use only these HARQ interlaces. In some cases, the access point 104 may arbitrarily select the parameters.

If the network node 114 does not specify a HARQ interlace or arbitrarily selects a HARQ interlace, the access point 104 may determine which N HARQ interlaces to use according to appropriate criteria. Thus, initially, this determination is based on (e.g., limited by) the value N. In some cases, access point 104 may define or override N (e.g., according to a standard as described above).

In some cases, the access point 104 may select the HARQ interlace associated with the lowest interference. Here, the access point 104 may determine which HARQ interlaces to use in a manner similar to that described above. For example, access point 104 may receive information (e.g., measurement reports, CQI, DRC) from access terminal 110. In addition, the access point 104 may monitor the uplink and/or downlink to determine interference on such links. For example, when the access point 104 is idle, it may monitor uplink interference (load) from outside the cell. In this way, the access point 104 may select the HARQ interlace that provides the least external cell interference.

In some cases, the access point 104 may cooperate with one or more other access points to determine the HARQ interlaces it will use. For example, the access point 104 and the access point 106 may negotiate to use different (e.g., mutually exclusive) HARQ interlaces.

As shown at block 410, the access point 104 may determine a timing offset to be used for uplink or downlink communications. For example, the access point 104 may continuously monitor the link over a period of time to determine when approximately neighboring nodes begin and end their transmissions. In this manner, the access point 104 may determine (e.g., estimate) the slot timing of the neighboring nodes. The access point may then synchronize its uplink or downlink slot timing with that time. In some aspects, this may include defining Tau-DPCH parameters.

In some cases (e.g., 3GPP), access points may synchronize their timing (e.g., HS-PDSCH timing) by time aligning their P-CCPCHs (primary common control physical channels). Such synchronization may be achieved, for example, by using GPS components in each access point, timing signaling between access points, which may be more efficient for neighboring nodes (e.g., tens of meters away from each other), or some other technique.

In some cases (e.g., in HSDPA), the overhead may be high and not orthogonal to the traffic. Here, discontinuous transmission or reception (DTX or DRX) may be used, whereby overhead is not transmitted during the DTX/DRX period. In this case, the transmission of CCPCH and EHICH may be considered, and the access terminals may be configured to consider the lower CPICH Ec/lo measurements they may see from the access point using DTX/DRX.

As shown at block 412, the access point 104 may send a message to the associated access terminal informing the access terminal which HARQ interlaces to use for uplink or downlink. In some implementations, the access point 104 can use E-AGCH (enhanced absolute grant channel) or some other similar mechanism to send HARQ interlace designations to the access terminals with which it is associated. For example, the access point 104 may set xggs-1 to specify which TTIs the access terminal is to use. In addition, the access point 104 may send an indication of the timing offset (e.g., the Tau-DPCH) determined at block 410 to the access terminal. In this way, the access point may schedule data transmission (uplink or downlink) on the best N HARQ interlaces of the available M HARQ interlaces (block 414).

The HARQ interlace parameters (e.g., N and the particular HARQ interlace used by a given node) as described above may be adjusted over time. For example, information as described above may be collected on a repeated basis, and the parameters adjusted accordingly (e.g., using hysteresis and/or slow filtering, if desired). In this way, HARQ interlaces can be deployed in a manner that takes into account current interference conditions in the system.

In some implementations, the HARQ interlaces may be allocated in a hierarchical manner. For example, if a restricted access point is not deployed in the coverage area of the macro access point, the macro access point is assigned a full set of HARQ interlaces (e.g., 8). However, where a restricted access point is deployed in the coverage area of the macro access point, a portion (e.g., 5) of the HARQ interlaces may be allocated for the macro coverage and another portion (e.g., 3) of the HARQ interlaces may be allocated for the restricted access point. The HARQ interlaces allocated for the restricted access points as described above may then be allocated among the restricted access points as described above (e.g., N-1). The number of HARQ interlaces allocated in this manner may be defined (e.g., adjusted in a fixed manner or dynamically) according to various criteria described herein (e.g., restricted access point deployment, traffic, interference, etc.). For example, as the number of restricted access points in the system or the amount of traffic at the restricted access points increases, the number of HARQ interlaces allocated for these access points may be increased.

Referring now to fig. 5 and 6, operations related to the use of a scheme for varying transmit power (e.g., downlink transmit power) over time to mitigate interference will be described in more detail. In some aspects, this scheme comprises: a transmit power curve, such as curve 602 shown in fig. 6, is defined that defines different power levels over time. Such a curve may take various forms and be defined in different ways. For example, in some cases, the curve may include a set of values defining the transmit power at different time instances. In some cases, the curve may be defined by an equation (e.g., a sine wave). In some aspects, the curve may be periodic. As shown in fig. 6, a maximum value (MAX), a minimum value (MIN), and a period 604 may be defined for the curve.

The transmit power curve may be used to control the transmit power in different ways. For example, in some cases, a transmit power profile is used to control the total transmit power. In some implementations, the overhead channels (e.g., CIPCH, etc.) and dedicated channels may operate at a constant power. The remaining power according to the transmit power curve may then be shared between other channels (e.g., HS-SCCH and HS-PDSCH). In some implementations, the overhead channels may be adjusted.

As described in more detail below, in some aspects, transmit power based fractional reuse may be achieved by using a transmit power curve. For example, neighboring access points may use the same curve (or similar curves), but do so according to different phases of the curve. For example, a first access point may transmit according to the curve shown in fig. 6, while a second access point transmits using the same curve phase shifted by 180 degrees. Thus, when the first access point transmits at maximum power, the second access point may transmit at minimum power.

As shown at block 502 of fig. 5, the network node 114 (e.g., the profile control component 342 of the interference controller 320) defines (e.g., specifies) transmit power profile information to be used for wireless transmission (e.g., on the downlink). This information may for example comprise parameters such as a transmit power curve, initial minimum and maximum values and initial period values.

In some cases, one or more of these parameters may be predefined or arbitrarily determined. However, in general, these parameters are selected in an attempt to more effectively mitigate interference between nodes in the system. The determination of this information may be based on various criteria, such as one or more measurement reports from one or more access terminals, one or more reports from one or more access points regarding CQI reported by one or more associated access terminals, the number of active access terminals, and the average downlink traffic at each access point (e.g., at each cell).

As a specific example, the definition of the transmit power curve parameters may be based on how the access points are deployed in the system (e.g., the total number of access points, the density of access points in a given area, and the relative proximity of the access points, etc.). Here, if there are a large number of nodes close to each other, the parameters may be defined such that it is unlikely that neighboring nodes will transmit at high power at the same time. As an example, the transmit power curve may be shaped such that a given access point may transmit for a short period of time at or near maximum power. In this manner, the transmit power profile may provide sufficient separation when various nodes in the system use a large number of phase values (e.g., 60 degrees, 120 degrees, etc.) in conjunction with the transmit power profile. Conversely, if there are a small number of nodes in the system, the parameters may be defined to improve communication performance (e.g., throughput). As an example, the transmit power curve may be shaped such that a given access point may transmit at or near maximum power for a longer period of time.

Different levels of separation between adjacent access points (e.g., cells) can also be achieved by adjusting the magnitude of the minimum and maximum parameters. For example, a larger max/min ratio provides better separation at the expense of the access terminal transmitting at a lower power level for a longer period of time.

The transmit power curve parameters may be defined in terms of the traffic (e.g., traffic load, traffic type, quality of service requirements of the traffic) handled by the access point. For example, some types of traffic may be more susceptible to interference than other types of traffic. In this case, parameters that provide higher separation (e.g., transmit power curve or maximum/minimum) may be used (e.g., as described above). In addition, some types of traffic may have more stringent throughput requirements (but less sensitive to interference), and thus, transmit power curves may be used that allow more transmissions at higher power levels (e.g., as described above).

In some cases, network node 114 may define the transmit power curve parameters from received interference-related information (e.g., feedback from one or more access points and/or access terminals in the system, as described above in connection with fig. 2). For example, the number of access points heard by a given access terminal and the relative proximity of the access points to the access terminal may be determined from measurement reports received from the access terminal. In this manner, the network node 114 may determine whether transmissions at a given cell (e.g., a cell associated with a restricted access point) are likely to interfere with neighboring cells and adjust the power curve parameters accordingly. Network node 114 may also define the parameters based on interference information received from one or more access points (e.g., as described in fig. 2).

In some implementations, the periodicity parameter may be defined in terms of a tradeoff between any delay sensitivity of the application data (e.g., VoIP) and the CQI/DRC filtering/delay (e.g., delay from the time the SINR is measured to when the access point's traffic scheduler is active). For example, if the cell is carrying a large amount of VoIP traffic, the periodicity may be set to correspond to the periodicity of VoIP packets. In some cases, a period in the range of 50-100 milliseconds may be appropriate. In some implementations, the periodicity parameter may be defined in terms of the number of access terminals being served.

As shown at block 504, in some cases, network node 114 may specify a particular phase offset value to be used by a particular access point. For example, network node 114 may determine an amount of interference that may be seen by a given access point when the access point uses different phase offset values (e.g., based on CQI reports received for each TTI). The phase offset associated with the lowest interference at that access point may then be assigned to the access point.

The network node 114 may also specify phase offset values for neighboring nodes in a manner that reduces interference between neighboring nodes. As a specific example, the network node 114 may determine that a downlink transmission by the access point 106 may interfere with reception at an access terminal associated with the access point 104. This may be determined, for example, from downlink interference related information available to network node 114, as described herein. The network node 114 may then specify different phase offset values (e.g., 180 degrees out of phase) for the access points 104 and 106.

The network node 114 then transmits its defined power curve information to one or more access points, as shown at block 506. Here, the network node 114 may send a node-specific designation to each access point, or the network node 114 may send a common designation to all access points in a set of access points.

As shown at blocks 508 and 510, the access point 104 (e.g., the profile control component 344 of the interference controller 322) determines transmit power profile parameters it will use for downlink communications. In the case where the network node 114 specifies all transmit power curve parameters to be used by the access point 104, the access point 104 may simply use these parameters. In some cases, the access point 104 may arbitrarily select a parameter (e.g., phase offset).

If all of the parameters are not specified by the network node 114 or are not arbitrarily selected, the access point 104 may determine which parameters to use according to appropriate criteria. In a typical case, the access point may implement a tracking algorithm to dynamically determine the phase offset values to be used in connection with the transmit power curve, minimum, maximum, and period parameters received by the access point 104 from the network node 114.

In some cases, the access point 104 may select the phase offset value associated with the lowest interference. Here, the access point 104 may determine which phase offset value to use in a similar manner as described above. For example, at block 508, the access point 104 may receive information (e.g., measurement reports, CQIs, DRCs) from the access terminal 110 and/or the access point 104 may monitor the link to determine interference on the link. As an example of the latter case, when the access point 104 is idle, it may monitor interference (load) on the downlink from outside the cell. In this manner, the access point 104 may select a phase offset value that provides the least external cell interference at block 510.

In some cases, the access point 104 may cooperate with one or more other access points to determine the phase offset value. For example, access point 104 and access point 106 may negotiate to use different (e.g., out of phase) phase offset values. In this case, the operation of block 508 may not be performed.

The access point transmits on the downlink according to the current transmit power curve, as shown in block 512. Thus, the transmit power may change over time in a manner that may mitigate interference to neighboring nodes.

The transmit power curve parameters described above (e.g., maximum, minimum, and period parameters defined by the network node 114) may be adjusted over time. For example, the above information may be collected on a repeated basis and the parameters adjusted accordingly (e.g., using hysteresis and/or slow filtering, if desired). In this manner, the transmit power of access terminals in the system can be controlled in a manner that takes into account the current interference conditions in the system. For example, if interference increases at a given node (e.g., as determined by CQI reports), the maximum power parameter may be decreased. In a simplified case, maximum _ i is set equal to minimum _ i for each access point i. Network node 114 may then attempt to set these values to provide the same (or substantially the same) average CQI in each cell, which may be achieved using Ec _ i, j/lo from each access point terminal j of each access point i.

Referring now to fig. 7 and 8, operations related to the use of a scheme for varying receive attenuation (e.g., uplink attenuation) over time to mitigate interference will be described in more detail. In some aspects, this scheme comprises: a receive attenuation curve, such as curve 802 shown in fig. 8, is defined that defines different attenuation levels over time. Such a curve may take different forms and be defined in different ways. For example, in some cases, a curve may include a set of values defining receive attenuation at different time instances. In some cases, the curve may be defined by an equation (e.g., a sine wave). As shown in fig. 8, a maximum value (MAX), a minimum value (MIN), and a period 804 may be defined for the curve.

As described in more detail below, in some aspects, receive attenuation based fractional reuse may be achieved by using a receive attenuation curve. For example, neighboring access points may use the same curve (or similar curves), but according to different phases of the curve. For example, a first access point may receive according to the curve shown in fig. 8, while a second access point receives using the same curve phase shifted by 180 degrees. Thus, when the first access point receives with maximum attenuation, the second access point may receive with minimum attenuation.

As shown at block 702 of fig. 7, the network node 114 (e.g., the curve component 342 of the interference controller 320) defines receive attenuation curve information to be used for wireless reception (e.g., on the uplink). Such information may for example include parameters such as receive decay curves, initial minimum and maximum values, and initial period values.

In some cases, one or more of these parameters may be predefined or arbitrarily determined. However, in general, these parameters are selected in an attempt to more effectively mitigate interference between nodes in the system. The determination of this information may be based on different criteria, such as one or more measurement reports from one or more access terminals, one or more reports from one or more access points regarding CQI reported by one or more associated access terminals, the number of active access terminals, and the average uplink traffic in each access point (e.g., in each cell).

As a specific example, the definition of the receive attenuation curve parameters may be based on how the access points are deployed in the system (e.g., total number of access points, density of access points in a given area, relative proximity of access points, etc.). Here, if there are a large number of nodes close to each other, the parameters may be defined such that it is unlikely that neighboring nodes receive at a high attenuation level at the same time. As an example, the receive attenuation curve may be shaped such that a given access point may receive a shorter period of time with a maximum attenuation or near maximum attenuation. In this manner, the receive attenuation curve may provide sufficient separation when each node in the system uses a large number of phase values (e.g., 60 degrees, 120 degrees, etc.) in conjunction with the receive attenuation curve. Conversely, if there are a small number of nodes in the system, the parameters may be defined to improve communication performance (e.g., throughput). As an example, the receive attenuation curve may be shaped such that a given access point may receive a longer period of time at or near a maximum attenuation level.

Different levels of separation between adjacent access points (e.g., cells) can also be achieved by adjusting the magnitude of the minimum and maximum parameters. For example, a larger max/min ratio provides better separation at the expense of the access terminal receiving a longer period of time with a lower attenuation level.

The receive attenuation curve parameters may be defined in terms of the traffic (e.g., traffic load, traffic type, quality of service requirements of the traffic) handled by the access point. For example, some types of traffic may be more susceptible to interference than other types of traffic. In this case, parameters that provide higher separation (e.g., receive attenuation curves or maxima/minima) may be used (e.g., as described above). In addition, some types of traffic may have more stringent throughput requirements (but less sensitive to interference), and thus, receive attenuation curves may be used that allow more transmissions at higher attenuation levels (e.g., as described above).

In some cases, network node 114 may define the receive attenuation curve parameters based on received interference-related information (e.g., feedback from one or more access points and/or access terminals in the system, as described above in connection with fig. 2). For example, the number of access points heard by a given access terminal and the relative proximity of the access points to the access terminal may be determined from measurement reports received from the access terminals. In this manner, the network node 114 may determine whether transmissions at a given cell (e.g., a cell associated with a restricted access point) are likely to interfere with neighboring cells and adjust the attenuation curve parameters accordingly. Network node 114 may also define the parameters based on interference information received from one or more access points (e.g., as described in fig. 2).

In some implementations, the periodicity parameter may be defined in terms of a tradeoff between any delay sensitivity of the application data (e.g., VoIP) and the filtering/delay of the downlink control channel (e.g., CQI/DRC, ACK channel, etc.), as described above.

As shown at block 704, in some cases, network node 114 may specify particular phase offset values and/or other parameters to be used by particular access points. For example, network node 114 may determine an amount of interference that may be seen by a given access point when the given access point uses different phase offset values. The phase offset associated with the lowest interference at that access point may then be assigned to the access point.

The network node 114 may also specify phase offset values for neighboring nodes in a manner that reduces interference between nodes. As a specific example, the network node 114 may determine that uplink transmissions by the access terminal 112 may interfere with reception at the access point 104. This may be determined, for example, from uplink interference related information available to network node 114, as described herein. The network node 114 may then specify different (e.g., 180 degrees out of phase) phase offsets for the access points 104 and 106.

The network node 114 then sends the attenuation curve information it defines to one or more access points, as shown in block 706. Here, the network node 114 may send a node-specific designation to each access point, or the network node 114 may send a common designation to all access points in a set of access points.

As shown at blocks 708 and 710, the access point 104 (e.g., the curve component 344 of the interference controller 322) determines the receive attenuation curve parameters it will use for uplink communications. In the case where the network node 114 specifies all of the receive attenuation curve parameters to be used by the access point 104, the access point 104 may simply use these parameters. In some cases, the access point 104 may arbitrarily select a parameter (e.g., phase offset).

If all of the parameters are not specified by the network node 114 or are not arbitrarily selected, the access point 104 may determine which parameters to use according to appropriate criteria. In a typical case, the access point may implement a tracking algorithm to dynamically determine the phase offset values to be used in connection with the receive attenuation curve, minimum, maximum, and period parameters received by the access point 104 from the network node 114.

In some cases, the access point 104 may select the phase offset value associated with the lowest interference. Here, the access point 104 may determine which phase offset value to use in a similar manner as described above. For example, at block 708, the access point 104 may receive information (e.g., measurement reports) from the access terminal 110 and/or the access point 104 may monitor the link to determine interference on the link. As an example of the latter case, when the access point 104 is idle, it may monitor interference (load) on the uplink from outside the cell. In this manner, the access point 104 may select a phase offset value that provides the least external cell interference at block 710.

In some cases, the access point 104 may cooperate with one or more other access points to determine the phase offset value. For example, access point 104 and access point 106 may negotiate to use different (e.g., out of phase) phase offset values. In this case, the operations of block 708 may not be performed.

The access point receives on the uplink in accordance with the current receive attenuation curve (e.g., by applying the attenuation curve to the received signal), as shown at block 712. Thus, the receive attenuation may change over time in a manner that may mitigate interference to neighboring nodes.

The receive attenuation curve parameters (e.g., maximum, minimum, and period parameters defined by the network node 114) as described above may be adjusted over time. For example, the above information may be collected on a repeated basis and the parameters adjusted accordingly (e.g., using hysteresis and/or slow filtering, if desired). In this manner, reception attenuation of access terminals in the system can be controlled in a manner that accounts for current interference conditions in the system. For example, the attenuation (e.g., maximum attenuation) may be increased as the received signal power level at one or more access points increases. In a simplified case, for each access point i, maximum _ i is set equal to minimum _ i and controlled in a similar manner as described above.

Referring now to fig. 9 and 10, operations related to the use of a fractional reuse scheme using selective transmission (e.g., puncturing) on the uplink or downlink will be described in more detail. As described above, a system may transmit during one or more defined slots, which may be referred to or referred to in various implementations as frames, subframes, slots, transmission time intervals ("TTIs"), HARQ interlaces, and so on.

In some aspects, a fractional reuse scheme may comprise: neighboring nodes (e.g., access points and/or access terminals) are configured to refrain from transmitting during a portion of one or more transmit time slots. For example, a first access point may transmit during a first portion of a slot (e.g., a portion of one subframe or an entire subframe) while a second access point transmits during a second portion of the slot (e.g., another portion of the subframe or a different entire subframe). As a result, interference between nodes that would otherwise occur can be reduced.

In some aspects, determining whether a node will refrain from transmitting during a given portion of a time slot may include: it is determined how much interference there is on different parts of the slot. For example, the node may refrain from transmitting on those portions of the time slot associated with higher interference.

Referring first to fig. 9, as shown at block 902, a network node 114 (e.g., the timeslot control component 346 of the interference controller 320) or some other appropriate entity may determine how a given transmission timeslot or a group of transmission timeslots is to be divided into portions such that different nodes may selectively refrain from transmitting during one or more of these timeslot portions. This may include, for example: parameters such as the structure of each slot portion, the number of slot portions, the size of each slot portion, and the location of each slot portion are determined. Here, it should be understood that a given timeslot segment may be defined to include sub-segments that are not contiguous in time, or may be defined to be a single continuous period. In some cases, these time slot parameters may be predefined for the system.

In some aspects, parameters of the timeslot segments are defined to mitigate interference in the system. To this end, the timeslot segments may be defined according to how the nodes are deployed in the system (e.g., total number of access points, density of access points in a given area, relative proximity of access points, etc.). Here, if a large number of nodes are deployed in a given area, more slot portions (e.g., and possibly smaller portions) may be defined and/or more separation may be provided between slot portions. In this way, it is unlikely that neighboring nodes will use the same timeslot segment (or interfere with neighboring timeslot segments), and any possible interfering node may thus be configured to not transmit during a larger percentage of a timeslot or set of timeslots. Conversely, if there are a smaller number of nodes in the system, fewer slot portions (e.g., and possibly larger portions with lesser degrees of separation) may be defined to improve communication performance (e.g., throughput).

The timeslot segments may also be defined according to the traffic handled by the access point (e.g., traffic volume, type of traffic, quality of service requirements of the traffic). For example, some types of traffic may be more susceptible to interference than other types of traffic. In this case, more slot portions may be defined and/or greater separation may be provided between slot portions. In addition, some types of traffic may have more stringent throughput requirements (but less sensitive to interference), and thus a larger portion of the slot may be defined.

The slot portion may also be defined in terms of interference in the system. For example, if the interference value is high in the system, more slot portions may be defined and/or greater separation may be provided between slot portions.

Accordingly, the operations of block 902 can be based on interference-related feedback from one or more access points and/or access terminals in the system (e.g., as described above). For example, access terminal measurement reports and/or reports from access nodes can be used to determine the degree to which nodes in the system interfere with each other.

As shown at block 904, in some cases, network node 114 may specify a particular portion of a time slot to be used by a particular node. In some cases, the slot portions may be allocated in any manner. In general, however, the time slots may be selected in an attempt to mitigate interference between nodes in the system. In some aspects, determining which portion of the time slot a given node should use may be similar to the operations of block 902 described above. For example, network node 114 may determine an amount of interference associated with a timeslot segment.

For the downlink, the access point may first be configured to use the first slot portion. The interference associated with the use of that portion of the time slot may then be determined (e.g., from CQI reports collected over a period of time). The access point may then be configured to use the second portion of time slots. Interference associated with use of the second portion of time slots may then be determined (e.g., based on CQI reports collected over a period of time). The network controller may then assign the access point a portion of the time slot associated with the lowest interference.

For the uplink, the access terminal may be configured to first use the first slot portion. The interference associated with the use of that portion of the time slot may be determined indirectly, e.g., based on a transmit power value used when transmitting on the uplink over a period of time (e.g., automatically set by a power control command from an associated access point). The access terminal may then be configured to use the second portion of the time slot. Interference associated with use of the second portion of time slots may then be determined (e.g., as described above). Network node 114 may then assign that access terminal and its associated access point the portion of the timeslot associated with the lowest interference (e.g., indicated by the lowest uplink transmit power).

The network node 114 may also designate portions of the time slots of neighboring nodes in a manner that mitigates interference between the nodes. As a specific example, the network node 114 may determine that downlink transmissions by the access point 106 would interfere with reception at an access terminal associated with the access point 104. This may be determined, for example, from downlink interference related information that may be obtained by the network node 114, as described herein. To mitigate this possible interference, the network node 114 may assign different portions of the time slot to the access points 104 and 106.

As shown at block 906, the network node 114 may determine a timing offset for one or more access points to synchronize the access point's slot timing. Such synchronization may be achieved, for example, using an adjustment such as the Tau-DPCH (where the DPCH involves a dedicated physical channel) or some other suitable synchronization scheme.

The network node 114 then transmits its defined slot portion parameters to one or more access points, as shown at block 908. For example, the network node 114 may send a node-specific designation to each access point, or the network node 114 may send a common designation to all access points in a set of access points. The network node 114 may also send one or more timing offset indications to the access point for use in synchronization operations.

Referring now to fig. 10, this flow chart depicts operations that may be performed by an access point for downlink operation or an access terminal for uplink operation. First, the downlink case will be handled.

As shown at block 1002, the access point 104 (e.g., the timeslot control component 348 of the interference controller 322) determines a portion of the timeslot it will use for downlink communications. In the case where the network node 114 specifies portions of the time slots to be used by the access point 104, the access point 104 may use only those portions of the time slots. In some cases, the access point 104 may arbitrarily select which portion of the time slot to use.

If the network node 114 does not specify the timeslot segment or arbitrarily select the timeslot segment, the access point 104 may determine which timeslot segment to use according to appropriate criteria. In some aspects, the access point 104 may select the portion of the timeslot associated with the lowest interference. Here, the access point 104 may determine which portion of the time slot to use in a similar manner as described above at block 904 (e.g., by using different portions over different periods of time and monitoring the CQI or some other parameter during each period).

In some cases, the access point 104 may cooperate with one or more other access points to determine which portion of the time slot to use. For example, access point 104 and access point 106 may negotiate to use different (e.g., mutually exclusive) portions of the time slot.

As shown at block 1004, the access point 104 may determine a timing offset to be used for downlink communications. For example, the access point 104 may continuously monitor the link over a period of time to determine when the neighboring node approximately starts and ends its transmission. In this manner, the access point 104 may determine (e.g., estimate) the slot portion timing of the neighboring nodes. The access point may then synchronize its downlink slot timing portion with that time. In some aspects, this may include defining Tau-DPCH parameters.

As shown at block 1006, the access point 104 can send a message (e.g., including timing offset information) to the associated access terminals to inform the access terminals of which portions of the time slots are to be used for downlink. In this manner, the access point 104 may schedule downlink transmissions on the best available portion of the time slot (block 1008).

Turning now to the uplink case, as shown at block 1002, the access point 104 (e.g., the interference controller 324) determines the portion of the timeslot it will use for uplink communications. Where network node 114 specifies portions of time slots to be used by access terminal 110, access terminal 110 may use only those portions of time slots. In some cases, access terminal 110 may arbitrarily select which portion of the time slot to use.

If network node 114 does not specify a slot portion or arbitrarily select a slot portion, access terminal 110 may determine which slot portion to use according to appropriate criteria. In some aspects, access terminal 110 may select the portion of the timeslot associated with the lowest interference (e.g., lowest transmit power). Here, access terminal 110 may determine which portion of the time slot to use in a similar manner as described above at block 904, or this may occur automatically due to power control operations of access point 104.

In some cases, the access point 104 may monitor uplink interference during the timeslot segment tests (e.g., tests to determine which timeslot segment has the lowest interference). In this case, the access point 104 may instruct the access terminal 110 to use a particular portion of the time slot during a given phase of the interference test. Alternatively, access terminal 110 may inform access point 104 that those portions of the time slot are being used for a given phase of testing.

In some cases, the access point 104 may cooperate with one or more other access points to determine which portion of the uplink time slot to use. For example, access point 104 and access point 106 may negotiate to use different (e.g., mutually exclusive) portions of the time slot. In this case, the access point 104 may forward this information to the access terminal 110.

As shown in block 1004, access terminal 110 may determine a timing offset to be used for uplink or downlink communications. For example, access terminal 110 may continuously monitor the link over a period of time to determine when the neighboring node approximately starts and ends its transmission. In this manner, access terminal 110 may determine (e.g., estimate) the slot portion timing of the neighboring node. Alternatively, the access terminal 110 may receive timing offset information (e.g., Tau-DPCH parameters) from the access point 104. In either case, access terminal 110 may then synchronize the slot timing portion of its uplink with that time.

As shown at block 1006, access terminal 110 may send a message to access point 104 to inform access point 104 which slot portions to use for the uplink. In this manner, access terminal 110 may schedule uplink data transmission on the best available slot portion (block 1008).

The above operations may be performed on a repeated basis in an attempt to continuously provide the best slot portions to the nodes in the system. In some cases, it may be decided not to transmit during a particular pilot bit time to provide a more accurate SNR estimate (e.g., for EV-DO). In some cases, it may be decided not to transmit during a particular overhead channel to provide better isolation (e.g., for HSPA). In addition, the access terminals can be configured to take into account the lower signal measurements they can see from the access point using the above scheme.

Referring now to fig. 11 and 12, operations related to the use of a fractional reuse scheme using a spectral mask on the uplink or downlink will be described in more detail. In some aspects, such a scheme may include: neighboring nodes (e.g., access points and/or access terminals) are configured to use different spectral masks when transmitting. Here, instead of using all available spectrum with constant power, each node may use a spectral mask to establish a non-uniform power spectral density. For example, a first access point may transmit using a spectral mask associated with a first set of spectral components (e.g., a first subset of allocated spectrum), while a second access point may transmit using another spectral mask associated with a second set of spectral components (e.g., a second subset of allocated spectrum). As a result, interference that would otherwise occur between nodes can be reduced.

In some aspects, the determination of whether a node will use a given spectral mask may comprise: it is determined how much interference is seen when different spectral masks are used. For example, a node may choose to use a spectral mask associated with lower interference. Here, it should be understood that a given spectral mask may be defined to include spectral components that are discontinuous in frequency, or may be defined as a single continuous range of frequencies. Also, the spectral mask may include a positive mask (e.g., defining frequency components to be used) or a negative mask (e.g., defining frequency components not to be used).

Referring first to fig. 11, as shown at block 1002, the network node 114 (e.g., the spectrum mask controlling component 350 of the interference controller 320) may receive information representing interference associated with different spectral components of a spectrum allocated for uplink or downlink transmissions.

Accordingly, the operations of block 1102 may be based on interference-related feedback from one or more access points and/or access terminals in the system (e.g., as described above). For example, access terminal measurement reports and/or reports from access nodes may be used to determine the degree to which nodes in the system may interfere with each other when using a given spectral mask.

As shown in block 1104, in some cases, the network node 114 may specify a particular spectrum mask to be used by a particular node. In some cases, the spectral mask may be allocated in any manner. In general, however, the spectral mask may be selected in an attempt to more effectively mitigate interference between nodes in the system.

For example, for the downlink, the access point may first be configured to use a first spectral mask (e.g., a filter defined with specific spectral characteristics) when transmitting. The spectral mask may, for example, be limited to a substantially first half of the allocated spectrum (e.g., the spectral mask has substantially a full power spectral density for one half of the spectrum and a substantially reduced power spectral density for the other half of the spectrum). The interference associated with the use of that spectral mask may then be determined (e.g., from CQI reports collected over a period of time). The access point may then be configured to use a second spectral mask (e.g., which is substantially limited to the second half of the allocated spectrum). Interference associated with the use of the second spectral mask may then be determined (e.g., from CQI reports collected over a period of time). The network node 114 may then assign the access point a spectral mask associated with the lowest interference.

For the uplink, the access terminal may first be configured to use a first spectral mask when transmitting. The interference associated with the use of that spectral mask may then be determined (e.g., based on uplink interference measured by the associated access terminal). The access terminal may then be configured to use the second spectral mask and determine interference associated with the use of the second spectral mask. The network node 114 may then assign the access terminal a spectral mask associated with the lowest interference.

The network node 114 may also specify the spectral mask of neighboring nodes in a manner that mitigates interference between nodes. As a specific example, the network node 114 may determine that downlink transmissions by the access point 106 would interfere with reception at an access terminal associated with the access point 104. This may be determined, for example, based on downlink interference related information that may be obtained by the network node 114, as described herein. To mitigate such possible interference, the network node 114 may assign different spectral masks to the access points 104 and 106.

The network node 114 then transmits its identified spectral mask to the appropriate access point or points, as shown at block 1106. Here, the network node 114 may send a node-specific message to each access point, or the network node 114 may send a common message to all access points in a group of access points.

Referring now to fig. 12, a flow diagram depicts operations that may be performed by an access point and associated access terminal for uplink and downlink operations. As shown at block 1202, the access point 104 (e.g., the spectral mask control component 352 of the interference controller 322) determines a spectral mask to be used for the uplink or downlink. In the case where the network node 114 specifies the spectral mask to be used, the access point 104 may use only the specified spectral mask. In some cases, the access point 104 may arbitrarily select which spectral mask to use.

If the network node 114 does not specify a spectral mask or arbitrarily select a spectral mask, the access point 104 may determine which spectral mask to use according to appropriate criteria. In some aspects, the access point 104 may select the spectral mask associated with the lowest interference. For example, the access point 104 may determine which spectrum mask to use in a similar manner as described above in blocks 1102 and 1104 (e.g., by using different spectrum masks over different time periods and monitoring CQI or some other interference-related parameter during each time period).

In some cases, the access point 104 may cooperate with one or more other access points to determine which spectral mask to use. For example, access point 104 and access point 106 may negotiate to use different (e.g., mutually exclusive) spectral masks.

As shown at block 1204, access point 104 sends a message to access terminal 110 to inform access terminal 110 of which spectral mask to use for the uplink (or, alternatively, the downlink). In this manner, access point 104 may transmit on the downlink using the best available spectrum and/or access terminal 110 may transmit on the uplink using the best available spectrum (block 1206). Here, an equalizer at a receiving node (e.g., an access terminal for the downlink) may mitigate the effects of spectral shadowing (especially if there is no load from neighboring cells). Additionally, in some cases, the equalizer may be adaptive and take into account a particular spectral mask used at the transmitting node (e.g., an access point for the downlink).

The above operations may be performed on a repeated basis in an attempt to continuously provide the best spectral mask for the nodes in the system.

Reference is now made to fig. 13 and 14, which describe operations associated with the use of a fractional reuse scheme using spreading codes, e.g., walsh codes or OVSF codes (variable rate orthogonal spreading codes). In some aspects, such a scheme may include: neighboring nodes (e.g., access points) are configured to use different spreading codes when transmitting. Here, instead of using all codes in the assigned set of spreading codes, each node may use a subset of the spreading codes. For example, a first access point may transmit using a first set of spreading codes, while a second access point transmits using a second set of spreading codes. As a result, interference that would otherwise occur between nodes can be reduced.

In some aspects, the determination as to whether a node will use a given spreading code may comprise: it is determined how much interference is seen when different spreading codes are used. For example, the node may choose to use a spreading code associated with lower interference.

Referring first to fig. 13, as shown at block 1302, network node 114 (e.g., spreading code control component 354 of interference controller 320) may receive information indicative of interference associated with different subsets of spreading codes of a set of spreading codes allocated for downlink transmission.

Accordingly, the operations of block 1302 can be based on interference-related feedback from one or more access points and/or access terminals in the system (e.g., as described above). For example, access terminal measurement reports and/or reports from access nodes may be used to determine the extent to which nodes in the system may interfere with each other when using a given spreading code.

As shown at block 1304, in some cases, the network node 114 may specify a particular spreading code to be used by a particular node. In some cases, the spreading codes may be allocated in any manner. In general, however, the spreading codes may be selected in an attempt to more effectively mitigate interference between nodes in the system.

For example, the access point may first be configured to use a first set of spreading codes when transmitting on the downlink. Interference associated with the use of the set of spreading codes may then be determined (e.g., from CQI reports collected over a period of time). The access point may then be configured to use the second set of spreading codes and determine interference associated with the use of the second set of spreading codes. The network node 114 may then assign the spreading code associated with the lowest interference to the access point.

The network node 114 may also specify the spreading codes of neighboring nodes in a manner that mitigates interference between nodes. As a specific example, the network node 114 may determine that downlink transmissions by the access point 104 may interfere with reception at an access terminal associated with the access point 106. This may be determined, for example, from downlink interference related information that may be obtained by the network node 114, as described herein. To mitigate such possible interference, the network node 114 may assign different spreading codes to the access points 104 and 106.

Network node 114 then transmits its identified spreading code to one or more appropriate access points, as shown at block 1306. Here, the network node 114 may send a node-specific message to each access point, or the network node 114 may send a common message to all access points in a group of access points.

Network node 114 may also transmit one or more other sets of spreading codes to one or more access points, as shown in block 1308. As described in more detail below, these groups may identify spreading codes that are not used by a given access point and/or spreading codes that are used by some other access point.

Referring now to fig. 14, the access point 104 (e.g., spreading code control component 356 of the interference controller 322) determines a set of spreading codes to be used for the downlink, as shown at block 1402. Where the network node 114 specifies a group to use, the access point 104 may use only the specified group. In some cases, the access point 104 may arbitrarily select which set of spreading codes to use.

If the network node 114 does not specify the spreading codes of the group or arbitrarily selects the spreading codes of the group, the access point 104 may determine which group to use according to appropriate criteria. In some aspects, the access point 104 may select a set of spreading codes associated with the lowest interference. For example, the access point 104 may determine which group to use in a similar manner as described above at blocks 1302 and 1304 (e.g., by using different spreading codes over different time periods and monitoring the CQI or some other interference-related parameter during each time period).

In some cases, the access point 104 may cooperate with one or more other access points to determine which set of spreading codes to use. For example, access point 104 and access point 106 may negotiate to use different (mutually exclusive) sets of spreading codes.

As shown at block 1404, the access point 104 can optionally synchronize its timing with the timing of one or more other access points. For example, by achieving chip alignment with neighboring cells (e.g., cells associated with other restricted access points), orthogonal channels can be established between access points by using different spreading codes at each access point. Such synchronization may be accomplished, for example, using techniques as described above (e.g., an access point may include GPS functionality).

As shown at block 1406, the access point 104 may optionally determine a spreading code used by one or more other access points. Such information may be obtained, for example, from network node 114 or directly from other access nodes (e.g., via a backhaul).

Access point 104 sends a message to access terminal 110 to inform access terminal 110 of which spreading code to use for the downlink, as shown at block 1408. In addition, access point 104 may send information to access terminal 110 identifying spreading codes that are not used by access point 104 and/or identifying spreading codes that are used by some other access point (e.g., a neighboring access point).

The access point 104 transmits on the downlink using the selected set of spreading codes, as shown at block 1410. In addition, access terminal 110 decodes the information it received via the downlink using the spreading code information transmitted by access point 104, as shown at block 1412.

In some implementations, the access terminal 110 may be configured to use information about spreading codes not used by the access point 104 to more efficiently decode the received information. For example, the signal processor 366 (e.g., including interference cancellation capabilities) may use these other spreading codes in an attempt to cancel interference from the received information that is generated by signals received from another node (e.g., access point 106) that is encoded using these other spreading codes. Here, the other spreading codes are used to manipulate the originally received information to provide decoded bits. A signal is then generated from the decoded bits and subtracted from the originally received information. The resulting signal is then manipulated using a spreading code transmitted by the access point 104 to provide an output signal. Beneficially, by using such interference control techniques, a higher level of interference mitigation may be achieved even when the access point 104 and the access terminal 110 are not synchronized in time.

The above operations may be performed on a repeated basis in an attempt to continuously provide the nodes in the system with the optimal spreading codes.

Referring now to fig. 15 and 16, operations related to the use of power control related schemes for mitigating interference will be described. In particular, the operations relate to controlling transmit power of an access terminal to mitigate interference that the access terminal may cause on an uplink of a non-associated access point (e.g., operating on the same carrier frequency of adjacent carrier frequencies).

As shown at block 1502, a node (e.g., network node 114 or access point 104) receives a power control-related signal that can be used to determine how to control uplink transmit power of access terminal 110. In various instances, the signal may be received from network node 114, access point 104, another access point (e.g., access point 106), or an associated access terminal (e.g., access terminal 110). Such information may be received in various ways (e.g., over a backhaul, over the air, etc.).

In some aspects, the received signals may provide an indication of interference at neighboring access points (e.g., access point 106). For example, as described herein, an access terminal associated with the access point 104 may generate measurement reports and send these reports to the network node 114 via the access point 104.

In addition, an access point in the system can generate a load indication (e.g., a busy bit or relative grant channel) and send this information via the downlink to its associated access terminals. Thus, the access point 104 may monitor the downlink to obtain this information, or the access point 104 may obtain this information from its associated access terminals that may receive this information over the downlink.

In some cases, the interference information may be received from the network node 114 or the access point 106 via a backhaul. For example, the access point 106 may report its load (e.g., interference) information to the network node 114. The network node 114 may then distribute this information to other access points in the system. In addition, the access points in the system may communicate directly with each other to inform each other of their respective load conditions.

As shown at block 1504, a transmit power indication for access terminal 110 is defined as a function of the aforementioned parameters. This indication may relate to, for example, a maximum allowed power value, an instantaneous power value, or a traffic-to-pilot (T2P) indication.

In some aspects, a maximum transmit power value for access terminal 110 is defined by estimating interference that access terminal 110 may cause at access point 106. This interference may be estimated, for example, based on path loss information derived from measurement reports received from access terminal 110. For example, access terminal 110 may determine a path loss to access point 106 among the path losses to access point 104. From this information, the access point 104 may determine the power (e.g., amount of interference) incurred at the access point 106 based on the signal strength of the signal received by the access point 104 from the access terminal 110. The access point 104 may thus determine the maximum allowed transmit power for the access terminal 110 based on the measurements described above (e.g., the maximum transmit power may be reduced by a particular amount).

In some aspects, an instantaneous power value may be generated to control a current transmit power of an access terminal. For example, in the event the amount of interference caused is greater than or equal to a threshold value, access terminal 110 may be instructed to reduce its transmit power (e.g., by a particular amount or to a specified value).

In some cases, the power control operation may be based on one or more parameters. For example, if the access point 104 receives a busy bit from the access point 106, the access point 104 may use information from the measurement report to determine whether interference at the access point 106 is being caused by the access terminal 110.

Referring now to fig. 16, in some implementations, the transmit power indication generation block 1504 may relate to a maximum uplink T2P. Also, in some cases, this value may be defined as a function of the downlink SINR. Waveform 1602 of fig. 16 shows an example of a function relating downlink SINR to uplink T2P. In this case, the uplink T2P application may be reduced when the downlink SINR is reduced. In this way, uplink interference from access terminals with link imbalance may be limited. As shown in the example of fig. 16, a minimum T2P value 1604 may be defined for an access terminal to ensure a certain amount of minimum weighting. Additionally, a maximum T2P value 1606 may be defined. In some aspects, the uplink T2P assigned to each access terminal may be limited by a minimum value of the power headroom of the access terminal or a function based on the downlink SINR (e.g., as shown in fig. 16). In some implementations (e.g., 3GPP), the above-described functionality can be provided by an uplink scheduler, which is an access point that can access CQI feedback from an access terminal.

Referring again to fig. 15, as shown at block 1506, in some implementations, the rise-over-thermal ("RoT") threshold value of the access point may be allowed to increase above a conventional value for load control purposes. For example, in some cases, no limit is imposed on the RoT threshold value. In some cases, the RoT threshold value may be allowed to rise to a value limited only by the uplink link budget or saturation level at the access point. For example, in the access point 104, the upper threshold value, RoT, may be increased to a predetermined value to enable each associated access terminal to operate at the highest T2P level allowed by its power headroom.

By allowing such an increase in the RoT threshold, the access point can control its overall received signal strength. This may prove beneficial in cases where the access point is experiencing high interference levels (e.g., from nearby access points). However, without the RoT threshold limit, access terminals in neighboring cells may enter into a power race to overcome each other's interference. For example, these access terminals may saturate at their maximum uplink transmit power (e.g., 23dBm) and, as a result, may cause significant interference at the macro access point. To prevent such race conditions, the transmission power of the access terminal may be reduced as a result of an increase in the RoT threshold value. In some cases, such race conditions may be avoided by using a maximum uplink T2P control scheme (e.g., as described above in connection with fig. 16).

As shown at block 1508, an indication of a transmit power value (e.g., maximum power, instantaneous power, or T2P) calculated using one or more techniques as described above may be sent to access terminal 110 to control the transmit power of access terminal 110. Such a message may be sent directly or indirectly. As an example of the former case, explicit signaling may be used to inform access terminal 110 of the new maximum power value. As an example of the latter case, access point 104 may adjust T2P or may forward a load indication (possibly after some modification) from access point 106 to access terminal 110. Access terminal 110 may then use this parameter to determine a maximum power value.

Referring now to fig. 17, in some implementations, a signal attenuation factor may be adjusted to mitigate interference. Such parameters may include noise factor or attenuation. Such amount of fill or signal attenuation may be dynamically adjusted based on signal strengths measured from other nodes (e.g., as described herein) or specific signaling messages (e.g., indicating interference) exchanged between access points. In this manner, the access point 104 may compensate for interference caused by nearby access terminals.

As shown at block 1702, the access point 104 may receive a power control related signal (e.g., as described above). As shown at blocks 1704 and 1706, the access point 104 may determine whether the received signal strength from the associated access terminal or the unassociated access terminal is greater than or equal to a threshold level. If not, the access point 104 continues to monitor for power control related signals. If so, the access point 104 adjusts the attenuation factor at block 1708. For example, the access point 104 may increase its noise factor or receiver attenuation in response to an increase in received signal strength. As shown at block 1710, the access point 104 may send a transmit power control message to the access terminal with which it is associated to increase the uplink transmit power of the access terminal as a result of the increase in the attenuation factor (e.g., to overcome a noise factor or uplink attenuation imposed on the access point 104).

In some aspects, the access point 104 may distinguish signals received from unassociated access terminals from signals received from associated access terminals. In this manner, the access point 104 may make appropriate adjustments to the transmit power of the access terminal with which it is associated. For example, different adjustments may be made in response to signals from associated access terminals relative to signals from non-associated access terminals (e.g., depending on whether there is only one associated access terminal).

In another embodiment, an access point may perform interference mitigation for access terminals not served by the access point or for access terminals not in the access point's active set. For this purpose, the scrambling code (in WCDMA or HSPA) or the user long code (in 1 xEV-DO) may be shared among all access points that receive the scrambling code from all access terminals. The access point then decodes the respective access terminal information and removes interference associated with the respective access terminal.

In some aspects, the teachings herein may be used in networks that include macro-scale coverage (e.g., large area cellular networks such as 3G networks, which are commonly referred to as macro-cell networks) and smaller scale coverage (e.g., residential-based or building-based network environments). As AN access terminal ("AT") moves through such a network, the access terminal may be served by AN access node ("AN") that provides macro coverage in a particular location, while the access terminal may be served by AN access node that provides smaller scale coverage in other locations. In some aspects, a smaller coverage node may be used to provide increased capacity growth, coverage in a building, and different services (e.g., for a more robust user experience). In the discussion herein, a node that provides coverage over a larger area may be referred to as a macro node. Nodes that provide coverage over a smaller area (e.g., a residence) may be referred to as femto nodes. A node that provides coverage over an area that is smaller than a macro area and larger than a femto area may be referred to as a pico node (e.g., providing coverage in a commercial building).

The cells associated with a macro, femto, or pico node may be referred to as a macro, femto, or pico cell, respectively. In some implementations, each cell may be further associated with (e.g., divided into) one or more sectors.

In various applications, other terminology may be used to refer to macro, femto, or pico nodes. For example, a macro node may be configured or referred to as an access node, base station, access point, eNodeB, macro cell, and so on. Also, the femto node may be configured or referred to as a home nodeb, a home eNodeB, an access point base station, a femto cell, and the like.

Fig. 18 illustrates a wireless communication system 1800 configured to support multiple users in which the teachings herein may be implemented. System 1800 provides for communication for multiple cells 1802, such as macrocells 1802A-1802G, each of which is served by a corresponding access node 1804 (e.g., access nodes 1804A-1804G). As shown in fig. 18, access terminals 1806 (e.g., access terminals 1806A-1806L) can be dispersed at various locations throughout the system over time. Each access terminal 1806 may communicate with one or more access nodes 1804 on a forward link ("FL") and/or a reverse link ("RL") at a given moment, depending on whether the access terminal 1806 is active and whether it is in, for example, soft handoff. The wireless communication system 1800 may provide service over a large geographic area. For example, macro cells 1802A-1802G may cover some blocks in neighboring areas.

Fig. 19 illustrates an exemplary communication system 1900 in which one or more femto nodes are deployed in a network environment. In particular, the system 1900 includes multiple femto nodes 1910 (e.g., femto nodes 1910A and 1910B) installed in a smaller scale network environment (e.g., in one or more user residences 1930). Each femto node 1910 may be coupled to a wide area network 1940 (e.g., the internet) and a mobile operator core network 1950 via a DSL router, cable modem, wireless link, or other connectivity means (not shown). As described below, each femto node 1910 can be configured to serve associated access terminals 1920 (e.g., access terminal 1920A) and to selectively serve alien access terminals 1920 (e.g., access terminal 1920B). In other words, access to femto nodes 1910 can be restricted, such that a given access terminal 1920 can be served by a set of designated (e.g., home) one or more femto nodes 1910, but can not be served by any non-designated femto nodes 1910 (e.g., neighboring femto nodes 1910).

Fig. 20 shows an example of a coverage map 200 in which several tracking areas 2002 (or routing areas or location areas) are defined, each of which includes several macro coverage areas 2004. Here, the coverage areas associated with tracking areas 2002A, 2002B, and 2002C are depicted with wide lines, and macro coverage areas 2004 are represented by hexagons. The tracking area 2002 also includes a femto coverage area 2006. In this example, each femto coverage area 2006 (e.g., femto coverage area 2006C) is depicted in a macro coverage area 2004 (e.g., macro coverage area 2004B). It should be appreciated, however, that the femto coverage area 2006 may not be entirely within the macro coverage area 2004. In practice, a large number of femto coverage areas 2006 may be defined within a given tracking area 2002 or macro coverage area 2004. Also, one or more pico coverage areas (not shown) may be defined within a given tracking area 2002 or macro coverage area 2004.

Referring again to fig. 19, the owner of the femto node 1910 may subscribe to mobile services, such as 3G mobile services, provided through the mobile operator core network 1950. In addition, the access terminal 1920 may be capable of operating in macro environments and in smaller scale (e.g., residential) network environments. In other words, depending on the current location of the access terminal 1920, the access terminal 1920 may be served by an access node 1960 of the macro cell mobile network 1950 or by any one of a set of femto nodes 1910 (e.g., femto nodes 1910A and 1910B that reside in a corresponding user residence 1930). For example, when a subscriber is not at home, he is served by a standard macro access node (e.g., node 1960), and when the subscriber is at home, he is served by a femto node (e.g., node 1910A). Here, it should be appreciated that the femto node 1920 may be backward compatible with existing access terminals 1920.

Femto nodes 1910 may be deployed on a single frequency or, alternatively, on multiple frequencies. Depending on the particular configuration, the single frequency or one or more of the multiple frequencies may overlap with one or more frequencies used by a macro node (e.g., node 1960).

In some aspects, an access terminal 1920 can be configured to connect to a preferred femto node (e.g., a home femto node of the access terminal 1920) whenever such a connection is available. For example, whenever the access terminal 1920 is in the user's residence 1930, it may be desirable for the access terminal 1920 to communicate only with the home femto node 1910.

In some aspects, if the access terminal 1920 is operating in the macro cellular network 1950 but is not camped in its most preferred network (e.g., as defined in the preferred roaming list), the access terminal 1920 may continue searching for the most preferred network (e.g., the preferred femto node 1910) using a better system reselection ("BSR") that involves periodically scanning for available systems to determine if a better system is currently available, and then attempting to associate with such a preferred system. Using the acquisition terms, the access terminal 1920 may limit the search for particular frequency bands and channels. For example, the search for the most preferred system may be repeated periodically. Upon discovering the preferred femto node 1910, the access terminal 1920 selects the femto node 1910 for camping in its coverage area.

Femto nodes may be restricted in certain aspects. For example, a given femto node may only provide particular services to particular access terminals. In deployments that use so-called restricted (or closed) associations, a given access terminal may only be served by a macro cell mobile network and a defined set of femto nodes (e.g., femto nodes 1910 that reside in a corresponding user residence 1930). In some implementations, a node may be restricted to not provide at least one node with at least one of: signaling, data access, registration, paging, or service.

In some aspects, a restricted femto node (which may also be referred to as a closed subscriber group home node B) is a femto node that serves a restricted set of configured access terminals. The set may be expanded temporarily or permanently as desired. In some aspects, a closed subscriber group ("CSG") may be defined as a set of access nodes (e.g., femto nodes) that share a common access control list of access terminals. A channel on which all femto nodes (or all restricted femto nodes) in one area operate may be referred to as a femto channel.

Thus, various relationships can exist between a given femto node and a given access terminal. For example, from an access terminal perspective, an open femto node may refer to a femto node without restricted association. A restricted femto node may refer to a femto node that is restricted in some manner (e.g., restricted from association and/or registration). A home femto node may refer to a femto node on which an access terminal is authorized to access and operate. A visited femto node may refer to a femto node on which an access terminal is temporarily authorized to access or operate. A foreign femto node may refer to a femto node on which an access terminal is not authorized to access or operate except for possible emergency situations (e.g., 911 calls).

From the perspective of a restricted femto node, a home access terminal may refer to an access terminal that is authorized to access the restricted femto node. A visited access terminal may refer to an access terminal that temporarily accesses the restricted femto node. An alien access terminal may refer to an access terminal (e.g., an access terminal without credentials or permissions to register with a restricted femto node) that does not have permission to access the restricted femto node (except for possible emergency situations such as 911 calls).

For convenience, the disclosure herein describes various functionality in the context of a femto node. However, it should be understood that a pico node may provide the same or similar functionality for a larger coverage area. For example, a pico node may be restricted and a home pico node may be defined for a given access terminal, and so on.

A wireless multiple-access communication system may simultaneously support communication for multiple wireless access terminals. As described above, each terminal may communicate with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in single-out system, a multiple-in multiple-out ("MIMO") system, or some other type of system.

MIMO systems using multiple (N)_T) Transmitting antenna and a plurality of (N)_R) The receive antennas are used for data transmission. From N_TA transmitting antenna and N_RThe MIMO channel formed by the receiving antennas can be decomposed into N_SIndividual channels, which are also referred to as spatial channels, where N_S≤min{N_T，N_R}. Said N is_SEach of the individual channels corresponds to a dimension. MIMO systems may provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.

MIMO systems may support time division duplexing ("TDD") and frequency division duplexing ("FDD"). In a TDD system, the forward and reverse link transmissions are on the same frequency region, such that the reciprocity principle allows the estimation of the forward link channel from the reverse link channel. This enables the access point to extract transmit beamforming gain on the forward link when multiple antennas are available at the access point.

The teachings herein may be incorporated into a node (e.g., a device) that uses various means for communicating with at least one other node. Fig. 21 depicts several example components that may be employed to facilitate communications between nodes. In particular, fig. 21 illustrates a wireless device 2110 (e.g., an access point) and a wireless device 2150 (e.g., an access terminal) of a MIMO system 2100. At the device 2110, traffic data for a number of data streams is provided from a data source 2112 to a transmit ("TX") data processor 2114.

In some aspects, each data stream is transmitted over a respective transmit antenna. The TX data processor 2114 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor 2130. A data memory 2132 may store program code, data, and other information used by the processor 2130 or other components of the device 2110.

The modulation symbols for all data streams are then provided to a TX MIMO processor 2120, which TX MIMO processor 2120 can also process the modulation symbols (e.g., for OFDM). TX MIMO processor 2120 then feeds N_TA plurality of transceivers ("XCVR") 2122A through 2122T provide N_TA stream of modulation symbols. In some aspects, TX MIMO processor 2120 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transceiver 2122 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Then, respectively from N_TThe antennas 2124A through 2124T transmit N from the transceivers 2122A through 2122T_TA modulated signal.

At device 2150, from N_RThe transmitted modulated signals are received by antennas 2152A through 2152R, and the received signal from each antenna 2152 is provided to a respective transceiver ("XCVR") 2125A through 2125R. Each transceiver 2154 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signalTo provide samples, and further processes the samples to provide a corresponding "received" symbol stream.

A receive ("RX") data processor 2160 then converts the data from N according to particular receiver processing techniques_RA transceiver 2154 receives and processes N_RA received symbol stream to provide N_TA "detected" symbol stream. RX data processor 2160 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor 2160 is complementary to that performed by TX MIMO processor 2120 and TX data processor 2114 at device 2110.

A processor 2170 periodically determines which precoding matrix to use (as described below). Processor 2170 formulates a reverse link message comprising a matrix index portion and a rank value portion. A data memory 2172 may store program codes, data, and other information used by processor 2170 or other components of device 2150.

The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor 2138, modulated by a modulator 2180, conditioned by transceivers 2154A through 2154R, and transmitted back to device 2110, where TX data processor 2138 also receives traffic data for a number of data streams from a data source 2136.

At the device 2110, the modulated signals from the device 2150 are received by the antennas 2124, conditioned by the transceivers 2122, demodulated by a demodulator ("DEMOD") 2140, and processed by a RX data processor 2142 to extract the reverse link message transmitted by the device 2150. A processor 2130 then determines which pre-coding matrix to use for determining the beamforming weights then processes the extracted message.

Fig. 21 also illustrates that the communication components may include one or more components for performing interference control operations as taught herein. For example, an interference ("INTER") control component 2190 may cooperate with the processor 2130 and/or other components of the device 2110 to send/receive signals to/from another device (e.g., the device 2150), as taught herein. Similarly, the interference control component 2192 may cooperate with the processor 2170 and/or other components of the device 2150 to send/receive signals to/from another device (e.g., device 2110). It should be understood that the functionality of two or more of the described components may be provided by a single component for each of devices 2110 and 2150. For example, a single processing component may provide the functionality of the interference control component 2190 and the processor 2130 and a single processing component may provide the functionality of the interference control component 2192 and the processor 2170.

The teachings herein may be incorporated into various types of communication systems and/or system components. In some aspects, the teachings herein may be used in a multi-access system capable of supporting communication with multiple users by sharing available system resources (e.g., by specifying one or more bandwidths, transmit powers, coding, interleaving, and so forth). For example, the teachings herein may be applied to any one or combination of the following technologies: code division multiple access ("CDMA") systems, multi-carrier CDMA ("MCCDMA"), wideband CDMA ("W-CDMA"), high speed packet access ("HSPA", "HSPA +") systems, time division multiple access ("TDMA") systems, frequency division multiple access ("FDMA") systems, single carrier FDMA ("SC-FDMA") systems, orthogonal frequency division multiple access ("OFDMA") systems, or other multiple access techniques. A wireless communication system using the teachings herein may be designed to implement one or more standards such as IS-95, CDMA2000, IS-856, W-CDMA, TDSCDMA, and others. A CDMA network may implement a radio technology such as universal terrestrial radio access ("UTRA"), CDMA2000, or some other technology. UTRA includes W-CDMA and low chip rate ("LCR"). cdma2000 technology covers IS-2000, IS-95 and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications ("GSM"). OFDMA networks may implement techniques such as evolved UTRA ("E-UTRA"), IEEE 802.11, IEEE802.16, IEEE 802.20, Flash-OFDMEtc. radio technologies. UTRA, E-UTRA and GSM are part of the Universal Mobile Telecommunications System ("UMTS"). The teachings herein may be implemented in 3GPP long term evolution ("LTE") systems, ultra mobile broadband ("UMB") systems, and other types of systems. LTE is a release of UMTS that uses E-UTRA. While 3GPP terminology may be used to describe certain aspects of the present disclosure, it should be understood that the teachings herein may be applied to 3GPP (Re199, Re15, Re16, Re17) technologies as well as 3GPP2(1xRTT, 1xEV-DO ReIO, RevA, RevB) technologies and other technologies.

The teachings herein may be incorporated into (e.g., implemented in or performed by) various apparatuses (e.g., nodes). In some aspects, a node (e.g., a wireless node) implemented in accordance with the teachings herein may comprise an access point or an access terminal.

For example, an access terminal may comprise, be implemented as, or referred to as a user equipment, a subscriber station, a subscriber unit, a mobile station, a mobile node, a remote station, a remote terminal, a user agent, user equipment, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music device, a video device, or a satellite radio), a global positioning system device, or any other suitable device configured to communicate via a wireless medium.

An access point may include, be implemented as, or be referred to as a node B, eNodeB, a radio network controller ("RNC"), a base station ("BS"), a radio base station ("RBS"), a base station controller ("BSC"), a base transceiver station ("BTS"), a transceiver function ("TF"), a radio transceiver, a radio router, a basic service set ("BSs"), an extended service set ("ESS"), or some other similar terminology.

In some aspects, a node (e.g., an access point) may comprise an access point of a communication system. Such an access point may provide a connection for or to a network (e.g., a wide area network such as the internet or a cellular network), for example, via a wired or wireless communication link to the network. Thus, an access point may cause another node (e.g., an access terminal) to access a network or some other function. It should also be appreciated that one or both of the nodes may be portable or, in some cases, relatively non-portable.

Moreover, it should be appreciated that wireless nodes may be capable of transmitting and/or receiving information in a non-wireless manner (e.g., via a wired connection). Thus, the receivers and transmitters described herein may include appropriate communication interface components (e.g., electronic or optical interface components) for communicating via a non-wireless medium.

The wireless nodes may communicate via one or more wireless communication links that are based on or support any suitable wireless communication technology. For example, in some aspects a wireless node may be associated with a network. In some aspects, the network may include a local area network and a wide area network. The wireless device may support or use one or more of a variety of wireless communication technologies, protocols, or standards such as those described herein (e.g., CDMA, TDMA, OFDM, OFDMA, WiMAX, Wi-Fi, etc.). Similarly, the wireless node may support or use one or more of a plurality of corresponding modulation or multiplexing schemes. The wireless node may thus include appropriate components (e.g., air interfaces) to establish and communicate via one or more wireless communication links using the above-described or other wireless communication techniques. For example, a wireless node may include a wireless transceiver with associated transmitter and receiver components, which may include various components (e.g., signal generators and signal processors) to facilitate communication over a wireless medium.

The components described herein may be implemented in a variety of ways. Referring to fig. 22-30, apparatuses 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, and 3000 are represented as a series of interrelated functional blocks. In some aspects, the functionality of these blocks may be implemented as a processing system including one or more processor components. In some aspects, the functionality of these blocks may be implemented using, for example, at least a portion of one or more integrated circuits (e.g., an ASIC). As described herein, an integrated circuit may include a processor, software, other related components, or some combination thereof. The functions of these blocks may also be implemented in some other manner as taught herein. In some aspects, one or more of the dashed blocks in fig. 22-23 are optional.

Apparatuses 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, and 3000 may include one or more modules that may perform one or more of the functions described above with reference to the various figures. In some aspects, one or more components of interference controller 320 or interference controller 322 may provide functionality related to, for example: a HARQ interleaving component 2002, a curve illustration component 2302, a phase shift component 2402, an identification component 2502, a spectral mask component 2602, a spreading code component 2702, a processing component 2802, a transmit power component 2902, or an attenuation factor component 3004. In some aspects, the communication controller 326 or the communication controller 328 may provide functionality related to, for example, the components 2204, 2304, 2404, 2504, 2604, 2704, or 2904. In some aspects, timing controller 332 or timing controller 334 can provide functionality related to, for example, timing components 2206, 2506, or 2706. In some aspects, communications controller 330 may provide functionality related to, for example, receiving component 2802. In some aspects, the signal processor 366 can provide functionality relating to, for example, the processing component 2804. In some aspects, the transceiver 302 or the transceiver 304 may provide functionality related to, for example, the signal determination component 3002.

It will be understood that any reference herein to elements using designations such as "first" and "second" does not generally limit the number or order of those elements. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, reference to first and second elements does not imply that only two elements may be used therein, or that the first element must somehow precede the second element. Also, a set of elements can include one or more elements unless stated otherwise.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two, which may be designed using source coding or some other technique), various forms of program or design code containing instructions (which may be referred to herein, for convenience, as "software" or a "software module"), or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by an integrated circuit ("IC"), an access terminal, or an access point. The IC may include a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electronic components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute code or instructions that reside external to the IC, or both. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

It is understood that any specific order or hierarchy of steps in any disclosed process is an example of a sample approach. It will be appreciated that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure, depending upon design preferences. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or propagated as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one location to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. In general, it should be appreciated that a computer-readable medium may be implemented in any suitable computer program product.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (24)

1. A method of communication, comprising:

defining a transmit power curve, wherein the transmit power curve specifies how transmit power changes over time, and wherein the transmit power curve is periodic;

defining maximum and minimum power levels of the transmit power curve;

defining a time period of the transmit power curve;

indicating the transmit power profile to a plurality of access points, wherein at least a portion of the access points are neighboring access points;

assigning different transmit power curve phase offset values for different ones of the neighboring access points to mitigate downlink interference; and

indicating the transmit power curve phase offset value to the neighboring access point.

2. The method of claim 1, further comprising:

receiving information related to downlink interference; and

adjusting the maximum and minimum power levels and/or the time period in accordance with the information.

3. The method of claim 2, wherein the information comprises at least one downlink measurement report received from at least one access terminal associated with at least one of the access points.

4. The method of claim 1, further comprising:

adjusting the maximum and minimum power levels and/or the time period based on a number of active access terminals associated with the plurality of access points and/or based on downlink data traffic associated with the plurality of access points.

5. An apparatus for communication, comprising:

an interference controller to define a transmit power curve, to define maximum and minimum power levels of the transmit power curve, and to define a time period of the transmit power curve, wherein the transmit power curve specifies how transmit power changes over time, and wherein the transmit power curve is periodic; and

a communication controller to indicate the transmit power profile to a plurality of access points;

wherein at least a portion of the access points are neighboring access points;

wherein the interference controller is further configured to specify different transmit power curve phase offset values for different ones of the neighboring access points to mitigate downlink interference; and is

Wherein the communications controller is further configured to indicate the transmit power profile phase offset value to the neighboring access point.

6. The apparatus of claim 5, wherein:

the communications controller is further configured to receive information related to downlink interference; and

the interference controller is further configured to adjust the maximum and minimum power levels and/or the time period in accordance with the information.

7. The apparatus of claim 6, wherein the information comprises at least one downlink measurement report received from at least one access terminal associated with at least one of the access points.

8. The apparatus of claim 5, wherein the interference controller is further configured to adjust the maximum and minimum power levels and/or the time period based on a number of active access terminals associated with the plurality of access points and/or based on downlink data traffic associated with the plurality of access points.

9. An apparatus for communication, comprising:

means for defining a transmit power curve, maximum and minimum power levels of the transmit power curve, and a time period of the transmit power curve, wherein the transmit power curve specifies how transmit power changes over time, and wherein the transmit power curve is periodic; and

means for indicating the transmit power profile to a plurality of access points;

wherein at least a portion of the access points are neighboring access points;

wherein the means for defining is configured to assign different transmit power curve phase offset values for different ones of the neighboring access points to mitigate downlink interference; and is

Wherein the means for indicating is configured to indicate the transmit power curve phase offset value to the neighboring access point.

10. The apparatus of claim 9, wherein:

the means for indicating is further configured to receive information related to downlink interference; and

the means for defining is further for adjusting the maximum and minimum power levels and/or the time period based on the information.

11. The apparatus of claim 10, wherein the information comprises at least one downlink measurement report received from at least one access terminal associated with at least one of the access points.

12. The apparatus of claim 9, wherein the means for defining is further for adjusting the maximum and minimum power levels and/or the time period as a function of a number of active access terminals associated with the plurality of access points and/or as a function of downlink data traffic associated with the plurality of access points.

13. A method of communication, comprising:

defining a receive attenuation curve, wherein the receive attenuation curve defines attenuation values that differ over time;

defining maximum and minimum attenuation levels of the receive attenuation curve;

defining a time period of the receive decay curve;

indicating the receive attenuation profile to a plurality of access points, wherein at least a portion of the plurality of access points are neighboring access points;

assigning different receive attenuation curve phase offset values for different ones of the neighboring access points to mitigate uplink interference; and

indicating the receive attenuation curve phase offset value to the neighboring access point.

14. The method of claim 13, further comprising:

receiving information related to uplink interference; and

adjusting the maximum and minimum attenuation levels and/or the time period according to the information.

15. The method of claim 14, wherein the information relates to uplink interference monitored at least one of the access points.

16. The method of claim 13, further comprising: adjusting the maximum and minimum attenuation levels and/or the time period based on a number of active access terminals associated with the access point and/or based on uplink data traffic associated with the access point.

17. An apparatus for communication, comprising:

an interference controller for defining a receive attenuation curve, maximum and minimum attenuation levels of the receive attenuation curve, and a time period of the receive attenuation curve, wherein the receive attenuation curve defines attenuation values that differ over time; and

a communication controller to indicate the receive attenuation profile to a plurality of access points,

wherein at least a portion of the plurality of access points are neighboring access points,

wherein the interference controller is further configured to assign different receive attenuation curve phase offset values for different ones of the neighboring access points to mitigate uplink interference, and

wherein the communications controller is further configured to indicate the receive attenuation curve phase offset value to the neighboring access point.

18. The apparatus of claim 17, wherein:

the interference controller is configured to receive information related to uplink interference; and

the communication controller is configured to adjust the maximum and minimum attenuation levels and/or the time period based on the information.

19. The apparatus of claim 18, wherein the information relates to uplink interference monitored at least one of the access points.

20. The apparatus of claim 17, wherein the interference controller is further configured to adjust the maximum and minimum attenuation levels and/or the time period based on a number of active access terminals associated with the access point and/or based on uplink data traffic associated with the access point.

21. An apparatus for communication, comprising:

means for defining a receive attenuation curve, maximum and minimum attenuation levels of the receive attenuation curve, and a time period of the receive attenuation curve, wherein the receive attenuation curve defines attenuation values that differ over time; and

means for indicating the receive attenuation profile to a plurality of access points,

wherein at least a portion of the plurality of access points are neighboring access points,

wherein the means for defining is configured to assign different receive attenuation curve phase offset values for different ones of the neighboring access points to mitigate uplink interference, and

wherein the means for indicating is configured to indicate the receive attenuation curve phase offset value to the neighboring access point.

22. The apparatus of claim 21, wherein:

the means for indicating receives information related to uplink interference; and

the means for defining adjusts the maximum and minimum attenuation levels and/or the time period according to the information.

23. The apparatus of claim 22, wherein the information relates to uplink interference monitored at least one of the access points.

24. The apparatus of claim 21, wherein the means for defining adjusts the maximum and minimum attenuation levels and/or the time period as a function of a number of active access terminals associated with the access point and/or as a function of uplink data traffic associated with the access point.