KR200404025Y1 - Implementing a smart antenna in a wireless local area network - Google Patents

Abstract

A system for implementing smart antenna characteristics in a wireless local area network includes an AP and an STA. The AP includes a first antenna performance determination device; A first antenna performance information device configured to determine antenna performance of the AP by examining information stored in the first antenna performance information device; A first transceiver; A first antenna; And a beam switching device configured to switch beams of the first antenna, wherein the STA comprises: a second antenna; A second transceiver configured to receive antenna performance information of the AP; A second antenna performance determination device; A second antenna performance information device configured to compare antenna performance of the AP received from the second transceiver with antenna performance of the station retrieved from the second antenna performance information device; And a station setting adjusting device configured to adjust the setting of the station to use smart antenna performance.

Description

Method and system for implementing smart antenna in wireless local area network {IMPLEMENTING A SMART ANTENNA IN A WIRELESS LOCAL AREA NETWORK}

The present invention relates to a wireless local area network (WLAN), and more particularly, to implement a smart antenna in a WLAN, support the use of a smart antenna in a WLAN, and transmit smart antenna performance information between stations (STA) in a WLAN. A method and apparatus are disclosed.

In a WLAN operating in infrastructure mode, the STA typically performs scanning to estimate which access point (AP) is the best candidate for serving it. Scanning performed by the STA may be passive or active. In passive scanning, the STA listens to the beacon frame sent by the AP. In active scanning, the STA sends a probe request and the AP responds by sending a probe response to the STA.

In order to improve coverage and increase throughput, the AP may have an improved antenna structure, which allows to change the radiation pattern (beam) used by the AP. The term "smart antenna" as used herein refers to a series of N antennas with different radiation patterns that normally indicate a selected direction (or, in the case of an omnidirectional antenna, do not point to any particular direction). The transmitter and / or receiver of a node (AP or STA) selects the most appropriate antenna (or beam) and communicates with its counterpart. Typically, the most appropriate beam is to cause the highest signal to interference and noise ratio (SINR) at the receiving node in the case of a dedicated connection where one node transmits a packet to another node.

The improvement in coverage is a function of the location and time-varying channel of the STA transmitted by the AP. Because the beacon frames sent by the AP target multiple STAs rather than specific STAs, they tend to be transmitted uniformly in all directions (ie, with omni-directional beams). Similarly, since the AP preferably listens to packets from all of its associated STAs, the AP typically listens to the channel using an omni-directional beam. This type of beam does not necessarily require the AP to determine which beam is most helpful to the STA, even after receiving a probe request from the STA. Thus, the probe response also tends to be sent using an omnidirectional beam.

The STA uses beacons (passive scanning) and probe requests (active scanning) to estimate, among other things, the quality of the radio link (eg, signal-to-noise ratio (SNR)) that can be obtained from different APs. Beacon and probe responses are typically sent by the AP using omni-directional beams for the reasons described above. This is based on the received signal quality perceived from the beacon and / or probe response if, in practice, such an AP can perform poorly than other APs for the transmission of traffic frames that can be transmitted in a directional beam. Create a situation in which the STA can estimate that it is the best candidate.

1 illustrates an example WLAN 100 that includes a STA 102 and two APs, namely AP_A 110 and AP_B 120. The AP_A 110 may use the omni-directional beam 112 and the plurality of directional beams 114, 116, and 118. The AP_B 120 may use the omni-directional beam 122 and the plurality of directional beams 124, 126, and 128.

The STA 102 measures the received power of the various beams as shown in Table 1.

Signal Beam number Beam types Received Power at STA 102 AP_A 112 Omni-directional -75 dBm AP_A 116 Directivity -85 dBm AP_A 118 Directivity -85 dBm AP_B 122 Omni-directional -80 dBm AP_B 124 Directivity -70 dBm

Received signal power measured at the STA 102

The STA 102 may receive a stronger beacon and / or probe response from the AP_A 110 via the omni-directional beam 112 than through the omni-directional beam 122 from the AP_B 120. However, since AP_B 120 is in a better position to use its improved antenna structure and to focus energy towards the STA 102 (via the directional beam 124), AP_A ( May be a better candidate than 110).

In an AP based WLAN, multiple STAs may be associated with that AP at a given time. When the multiple access scheme is carrier simultaneous coexistence / collision detection (CSMA / CA) as in 802.11 based WLANs, it is easy for any STA to send packets (or also called frames) to the associated AP at any given point in time. . After the packet has been completely received and decoded, the AP determines which of the associated STAs sent the packet based on the source address contained in the packet's Media Access Control (MAC) header. Since the error detection bits covering both the MAC header and the MAC payload are received at the end of the packet, the AP needs to receive the entire packet before making the source decision.

In a mesh architecture, the STA (or mesh node) may also be equipped with a smart antenna to increase the SNR of the received signal or for other purposes such as interference reduction.

In an 802.11 based WLAN, the multiple access scheme makes it difficult to select the most appropriate beam for receiving packets at the AP when more than one STA is associated with the AP. This is because the STA may be placed anywhere around the AP, and thus the most appropriate beam is usually not the same for each STA. Since the identity of the STA is unknown until the packet is completely received, the AP cannot use this information to determine which antenna to select for packet reception. The same problem occurs in mesh architectures where mesh nodes can be connected to one or more mesh nodes.

In order to avoid this difficulty, several alternatives are possible, but all of them have disadvantages.

1) Since the AP may be limited to using an omnidirectional pattern in all packet reception, it may lose the possible benefit from the use of the smart antenna.

2) The AP may use signals from multiple beams simultaneously and combine them or select the optimal beam among them. This solution increases the complexity of the receiver because signals from multiple beams must be demodulated.

3) Immediately after initiation of packet reception, the AP may continuously switch among all its available beams, select the beam that produces the optimal signal quality, and switch to this beam for the remainder of the packet reception. This approach has the disadvantage that the AP risks receiving some bits incorrectly while attempting a less appropriate beam for a particular packet, causing loss of packets.

4) The AP may attempt to decode the transmitter's MAC address (included in the packet's MAC header) using an omni-directional antenna and then use the most appropriate beam for the STA identified in the MAC header for the remaining packets. The problem with this approach is that the MAC header is sent at the same rate as the rest of the packet. If the omni-directional antenna does not provide enough gain for proper signal quality for the MAC payload, the MAC header may not be decoded correctly. In the opposite case (when omnidirectional antennas provide sufficient gain), smart antennas may not be available, among other things.

5) The STA may be restricted to sending all packets using a Request-to-Send / Clear-to-Send (RTS / CTS) procedure. This may enable the AP to identify the transmission of the STA before the arrival of the data packet. However, the overhead of RTS and CTS packets sacrifices significant throughput penalties, which partly defeats the purpose of using smart antennas.

6) The AP in turn polls the STA using different beams. There are two problems with this approach. First, it is difficult to try to estimate the time spent for each beam in a system with burst traffic such as WLAN. Second, given the necessary overlap between antenna patterns and irregularities in the wireless environment, such as shadowing, the STA may transmit beams using sub-optimal (but audible) beams to them. It is difficult to respond to Paul.

In a WLAN, smart antenna performance may exist at the AP, at the STA, or both. Without exchanging the antenna performance information, the AP does not recognize the manner of adjusting the smart antenna characteristics by the characteristics of the STA, and vice versa.

Possible adverse effects on the WLN by not exchanging smart antenna performance information can be illustrated in the following example. Although switched beam smart antennas are used at both the AP and STA, the smart antenna performance at each end (e.g., the number of beam modes available and needs to be scanned as well as the time period required to test each of the available beams) It is not known at the other end. Since neither the AP nor the STA is aware of the smart antenna performance of its receiving end, each may either (1) infer about the smart antenna performance of the other end or (2) the receiving end may use its own beam search at the same time. You may have to test the transmission of your antenna beam without being aware of it.

If the smart antenna performance at both ends is known to each other, both devices can follow simple and preemptive rules that prevent service degradation due to beam retrieval at both ends simultaneously. For example, if the "beam search time" (T _search ) is known for both the AP and the STA, a simple rule that may be useful is that the device (AP or STA) that first received the packet after joining, may perform its beam search. In order to give the other end (which initiated the transmission) enough time to perform, it should wait the duration of the T _search before initiating its own beam search.

Current antenna technology improves reception using transmit and receive reception and / or transmit diversity. These techniques provide less gain than it would take longer or otherwise possible to achieve any gain. In addition, current antenna technology often needs to recognize antenna performance of the STA using a proprietary message. In the absence of such information, the AP and STA cannot use the antenna performance to increase the data rate or range.

In order for the smart antenna characteristic to operate effectively, information on the performance of the STA and the AP must be exchanged. The exchange of antenna information is also during optimization of the characteristics of the smart antenna, such as beam selection, beam scanning, beam shaping, multiple input multiple output (MIMO), and any other capabilities that allow changing the beam pattern and / or gain of the antenna. Make adjustments possible.

A method of implementing a smart antenna when establishing an association between an STA and an AP in a WLAN starts by transmitting a beacon frame by an AP on one antenna beam. The beacon frame is received at the STA, the STA measures the signal quality of the beacon frame. The AP switches to different antenna beams and repeats this method until the beacon frame is transmitted on all antenna beams. The STA is coupled to the AP that transmitted the beacon frame with the highest signal quality for one of its antenna beams. A similar method may be used in which the STA sends a probe request frame to the AP, and then the AP responds with a probe response frame sent on multiple antenna beams.

A system implementing a smart antenna for establishing a bond between an STA and an AP in a WLAN includes a beacon frame sent from the AP to the STA. The beacon frame includes a field that identifies the total number of antenna beams that can be transmitted and a field that identifies which beam is currently being transmitted.

Another system implementing the smart antenna when establishing a bond between an STA and an AP in a WLAN includes a probe request frame sent from the STA to the AP and a probe response frame sent from the AP to the STA. The probe request frame includes an indication of whether the STA wants not to scan multiple antenna beams from the AP. The probe response frame includes a field identifying the total number of antenna beams over which transmission can be made and a field identifying the beam currently being transmitted.

A method of supporting the use of a smart antenna in a WLAN including an AP and a STA begins by selecting an antenna beam by the AP to use for communication with the STA. The selected beam information is transmitted from the AP to the STA. The packet is sent from the STA to the AP, which includes the selected beam information, so that the AP receives at least a portion of the packet using the selected beam.

A system supporting the use of a smart antenna in a WLAN with an AP and a STA includes a first packet and a second packet. The first packet is transmitted from the AP to the STA and includes the selected beam indicator, the MAC address of the AP, and the MAC address of the STA. The selected beam indicator identifies the antenna beam selected by the AP for use for communication with the STA. The second packet is sent from the STA to the AP and includes the selected beam indicator, whereby the AP receives at least a portion of the second packet on the selected beam.

A system for exchanging smart antenna performance information between a transmitting STA and a receiving STA in a wireless communication system includes an antenna performance information element (IE). Antenna performance (IE) is transmitted from the transmitting STA to the receiving STA prior to data transmission between the transmitting STA and the receiving STA. When used in a WLAN, antenna performance (IE) may be transmitted as part of a management frame.

A method of exchanging smart antenna performance information between a transmitting STA and a receiving STA in a wireless communication system includes: transmitting antenna performance information from a transmitting STA to a receiving STA; Determining whether the receiving STA can support antenna performance of the transmitting STA; Adjusting a setting at the receiving STA if the receiving STA can support antenna performance of the transmitting STA; And when the receiving STA can support antenna performance of the transmitting STA, transmitting data from the transmitting STA to the receiving STA using the antenna performance.

A system for implementing smart antenna characteristics in a WLAN includes an AP and an STA. The AP includes a first antenna performance determination device; A first antenna performance information device connected to said first antenna performance determination device, said first antenna performance information device being configured to determine antenna performance of an AP by checking information stored in said first antenna performance information device; A first transceiver connected to said first antenna performance determination device; A first antenna connected to the transceiver; And a beam switching device connected to the transceiver, the beam switching device configured to switch the beam of the first antenna. The STA is a second antenna, a second transceiver connected to the second antenna, wherein the second transceiver is configured to receive antenna performance information from the ap; A second antenna performance determination device connected to the second transceiver; A second antenna performance information apparatus connected to the second antenna performance determination apparatus, wherein the second antenna performance determination apparatus comprises: antenna performance of a station retrieved from the second antenna performance information apparatus and antenna performance of an AP received from the second transceiver; Configured to compare-; And a station setting adjusting device connected to the second antenna performance determining device, wherein the station setting adjusting device is configured to adjust the setting of the station to use the smart antenna performance.

The invention may be understood in more detail from the description of the preferred embodiments which follow, which are provided by way of example in conjunction with the accompanying drawings.

Hereinafter, the term "station (STA)" includes, but is not limited to, a wireless transmit / receive unit, a user device, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. Hereinafter, an "access point" includes, but is not limited to, a base station, a Node B, a site controller, or any other type of interfacing device in a wireless environment.

The present invention solves the beam selection problem for both passive and active scanning. The present invention also relates to a signaling scheme and method that can be implemented by the AP and the STA to enable the use of a smart antenna at the AP for the reception of packets from the STA. This method can also be implemented with mesh nodes in the case of mesh architectures. The present invention solves the exchange of antenna performance information between the AP and the STA, establishes the current message provided by the 802.11 standard and has full backward compatibility.

Manual scanning

The present invention provides signaling and support for an AP to transmit its beacon on multiple beams. This can be accomplished by adding two fields to the WLAN beacon management frame as shown in FIG. The resulting management frame is called the enhanced antenna (AA) beacon frame 200. Many fields of frame 200 are within existing beacon frames, as defined by the 802.11 standard. These fields include Frame Control 202, Duration 204, Destination Address (DA; 206), Source Address (SA; 208), Basic Service Set (BSS) Identification (BSSID) 210, Sequence Control 212, Time Stamp 214, beacon interval 216, performance information 218, SSID information element (IE) 220, supported rate IE 222, frequency hopping (FH) / distribution system (DS) parameter set IE ( 224, a contention free (CF) parameter set IE 226, an independent BSS (IBSS) parameter set IE 228, and a traffic indication map (TIM) IE 230.

The first new field 232 of the frame 200 indicates an STA in which a beacon frame is transmitted N times within the AA beacon period, where N corresponds to the number of beacons in which the AP can transmit the beacon. The second new field 234 identifies the beam used to transmit the beacon, that is, the beam identifier. Upon receiving any of the plurality of AA Beacon frames transmitted by the AP, the STA may identify the number of beams 232 included in the beacon sweep performed by the AP and beam identifier 234. By observing, we can distinguish different versions that we receive.

The AA beacon section 216 may be set to the same or different value than the bea AA beacon section. Since the AA beacon interval must be larger than the beam scan interval in order for the system to serve the user, there is time left to transmit traffic frames. For example, it can be implemented as a configuration management rule that can prevent the user from configuring the AP so that the beam scan can take part of the AA beacon time period.

In a preferred embodiment, N AA beacon frames 200 are transmitted continuously in time. This is accomplished by having the AP use a delay X shorter than DIFS (distributed interframe space) but greater than SIFS (short interframe space) when attempting to access the wireless medium during transmission of two beacon frames. Any value of X between SIFS and DIFS can be used. The AP may still need to wait for one full DIFS when accessing the wireless medium and transmitting the first frame of the N beacon frames. This places an upper limit on the maximum amount of time that may be needed when the STA scans the medium if it detects one of the N beacons known by the AP:

Upper bound = (N-1) x (beacon_segment + X)

In other words, this does not recognize whether all N beacons have been sent by the AP and does not allow the STA to scan the channel for a predetermined amount of time.

A timing diagram for passive scanning is shown in FIG. 3. Before the AP initiates AA beacon interval 300, it waits for one DIFS 302. At the start of the AA beacon interval 300, the AP transmits a first beacon frame 304. Between beacon frames 304, the AP waits for interval X 306, where X is shorter than DIFS and greater than SIFS.

A method 400 of transmitting an AA beacon frame in passive scanning is shown in FIG. The method 400 transmits an AA beacon frame 200 on one of the N antenna beams, and starts with the current beam identifier 234 set on the current beam (step 402). A determination is made as to whether the AA Beacon frame has been transmitted on all N beams (step 404). If the AA Beacon frame has been transmitted on all N beams, the method ends (step 406). If the AA Beacon frame has not been transmitted on all N beams (step 404), the method waits for section X (step 408). The antenna system then switches to the next beam (step 408), the current beam identifier 234 is set to the current beam and transmits the AA beacon frame 200 on the current beam (step 410), which method is step 404. To last. Switching to the next beam (step 408) may be performed before or after waiting for interval X.

The determination used by the STA whether it is coupled to the AP is specific to the implementation. One method is to select an AP that binds to it using the SNR or power level perceived on the beacon. The present invention takes full advantage of the fact that the AP has an improved antenna system while allowing the STA to use this method.

Active scanning

The present invention also solves active scanning by allowing the STA to request the AP to send a probe response in multiple beams. This can be accomplished by adding a new frame to the WLAN probe request frame. The resulting frame is shown in FIG. 5 and is called AA probe request frame 500. Many fields of frame 500 are within existing probe request frames as defined by the 802.11 standard. These fields include frame control 502, duration 504, DA 506, SA 508, BSSID 510, sequence control 512, SSID IE 514, and supported rate IE 516. Include. The new field 518 of frame 500 provides an indication (as a value of yes or no) to the AP that the STA wants to scan all beams of the AP.

In addition, two new fields are added to the WLAN probe response frame. The resulting frame is shown in FIG. 6 and is called AA probe response frame 600. Many of the fields of frame 600 are in existing probe response frames as defined by the 802.11 standard. Fields 602-628 of frame 600 are the same as fields 202-228 of frame 200.

The first new field 630 of the frame 600 indicates to the STA that the AA probe response is transmitted N times within the AA beacon period, where N corresponds to the number of beacons to which the AP can transmit the probe response. The second new field 632 identifies the beam used to send the AA probe response, which is the beam identifier. The AP equipped with the AA system responds to the AA probe request by sending a plurality of (N) AA probe responses to the STA.

In a preferred embodiment, N AA probe responses are sent continuously in time. This is accomplished by having the AP use a delay (X) shorter than DIFS but greater than SIFS when trying to access the wireless medium between transmissions of two AA probe responses. When accessing the wireless medium and sending the first of the N probe responses, the AP may still need to wait for one full DIFS. It puts an upper limit on the maximum amount of time the STA may need to wait when receiving one of the N AA probe responses sent by the AP as follows:

Upper limit = (N-1) x (probe response interval + X)

A timing diagram for active scanning is shown in FIG. After the STA transmits the AA probe request frame 700, the AP waits for one DIFS 702 before transmitting the first AA probe response frame 704. Between probe response frames 704, the AP waits for section X 706, where X is shorter than DIFS but greater than SIFS.

A method 800 of transmitting an AA probe response frame in active scanning is shown in FIG. 8. The method 800 begins by the STA sending an AA probe request frame 500, such as setting the indication 518 to scan all beams of the AP (step 802). The AP receives the AA Probe Request frame and waits for a DIFS period (step 804). The AP sets the current beam identifier 632 to the current beam and transmits an AA probe response frame 600 in one of the N antenna beams (step 806). It is determined whether the AA probe response frame has been transmitted on all N beams (step 808). If the AA probe response frame has been sent on all N beams, the method ends (step 810). If the AA probe response frame has not been transmitted on all N beams (step 808), the method waits for interval X (step 812). The antenna system is then switched to the next beam (step 812), and the current beam identifier 632 is set to the current beam to transmit the AA probe response frame 600 to the current beam, and the method continues at step 808. . Switching to the next beam (step 812) may be performed before or after waiting for the interval X.

In conventional systems, the determination made by the STA as to which AP is coupled may not take into account the radio link gain obtained from the improved antenna structure at the AP. This means that data collected manually or actively from scanning in the RF environment, beacon frames and probe responses are transmitted by the AP in an omni-directional manner, providing poorer performance than other APs when gain from the AA system is considered. This means that the STA can be induced by combining with the AP.

According to the present invention, the data collected by the STA when scanning the RF environment enables to estimate which AP can provide the optimal radio link, so that the AA system can provide when traffic frames are transmitted. Benefits will be taken into account.

Beam Indicator

9 illustrates a system 900 operating in accordance with the present invention. The system 900 includes an AP 902, a first STA (STA 1; 904), and a second STA (STA 2; 906). The AP 902 uses the STA 1 904 to direct the omni-directional beam (or pattern b ₀ ; 910), the first directional beam b ₁ ; 912, and the STA 2 906 to the second directional beam. (b ₂ ) is transmitted. While the omni-directional beam 910 can be received (but weak) by the STA 1 904 and the STA 2 906, the directional beams 912, 914 are a better choice.

Hereinafter, a new field called "beam indicator" is added after the Physical Layer Convergence Protocol (PLCP) of most packets transmitted from the STA to the AP, so that any beam (or Indicates to the AP whether to select an antenna). Because some packets (such as an acknowledgment (ACK) or CTS) are to be received by the AP from a particular STA, the beam indicator need not be sent for every packet from the STA to the AP. If the AP knows in advance which STA can transmit the next packet, it can select the optimal beam to receive the packet, and no beam indicator is needed. However, the beam indicator may also be sent in these packets.

10 is a diagram illustrating a frame format 1000 that includes beam indicator information sent by a STA. Frame 1000 is a modified version of a PLCP PDU (PPDU) and includes a PLCP preamble 1002, a PLCP header 1004, a beam indicator field 1006, and a MAC frame 1008.

This information is provided by the STA transmitting the packet 1000 at the minimum data rate. The AP uses its omni-directional antenna to decode the PLCP header 1004 and the beam indicator field 1006. After decoding the beam indicator field 1006, the AP selects the corresponding beam to receive the remaining packet 1008, without having to be aware of the identity of the STA transmitting the packet 100.

Beam indicator 1006 is an integer between 0 and N _amax , where N _amax is the maximum number of beams that the AP can use. The value of N _amax may be fixed for all devices compatible with the system or may be signaled by the AP by a beacon frame, probe response frame or other management frame. Preferably, N _amax is a relatively small integer (ie, 7 or 15) to limit the number of additional bits needed for beam indicator field 1006. One of these values is reserved as a default for a situation where the STA does not know which value to use in the beam indicator field 1006. If this default value is used, the AP may simply use a beam that is not directed in a particular direction (such as an omnidirectional pattern).

The STA determines which value to use for the beam indicator field 1006 based on the information provided by the AP in previous AP to STA signaling. The information necessary for this signaling consists of the beam indicator itself along with the AP and STA MAC addresses. Optionally, a "age-limit" may be added to indicate to the STA a maximum value beyond which the beam indicator information is considered unreliable or invalid. The time limit may be a fixed value or may be signaled from a beacon frame, probe response frame or other management frame. In the latter case, the time limit may be adaptively set by the AP based on the STA mobility considerations.

There are several signaling possibilities for the AP to convey beam indicator information to the STA. One way is for the AP to send a special packet (beam indicator message) containing only the information needed for this purpose (AP and STA address, beam indicator, optional period limitation). 11 is a diagram illustrating a beam indicator message 1100 sent by an AP. This message 1100 includes a beam indicator field 1102, an AP address field 1104, a STA address field 1106, and an optional timeout field 1108. The order of the fields 1102-1108 is exemplary, and the fields 1102-1108 of the message 1100 can be in any order.

In a unicast situation, the STA preferably sends an ACK so that it can retransmit if the STA did not successfully receive the packet 1100. If an AP needs to update beam indicators for several STAs, it may send a multicast message for those STAs, including their respective beam indicator values.

Another signaling possibility is that the AP inserts or piggybacks the required information into a packet containing other data reaching this STA. This information may be added after the PLCP header, after the MAC PDU, or as another field in the MAC header. 12A and 12B are diagrams illustrating frame formats 1200 and 1220 including beam indicator information transmitted by an AP. Frames 1200 and 1220 are modified versions of the PPDUs.

12A shows a frame 1200 of adding beam indicator information after a PLCP header. Frame 1200 includes PLCP preamble 1202, PLCP header 1204, beam indicator field 1206, AP address field 1208, STA address field 1210, optional timeout field 1212, and MAC frame. 1212.

12B shows frame 1220 adding beam indicator information after MAC frame 1214. The field of the frame 1220 is the same as the frame 1200, but different from the order of the fields.

Another signaling possibility is to add a flag indicating whether beam indicator information is present. This flag may enable sending beam indicator information in every packet arriving at the STA. Beam indicator information may be transmitted periodically (eg, every 5 seconds) and / or in an event driven manner (eg, upon a change in beam transmitted from an AP to a particular STA).

13A and 13B are diagrams illustrating different frame formats 1300 and 1320, incorporating beam indicator information flags, including beam indicator information sent by an AP. Frames 1300 and 1320 are modified versions of the PPDUs. 13A shows a PLCP preamble 1302, a PLCP header 1304, a beam indicator information flag 1306, a beam indicator field 1308, an AP address field 1310, an STA address field 1312, and an optional time limit field ( 1314, and a frame 1300 including the MAC frame 1316. The flag 1306 is set only when the beam indicator information (fields 1308-1314) is provided to the frame 1300.

13B shows frame 1320 adding beam indicator information after MAC frame 1316. The fields of the frame 1320 are the same as the frame 1300, but the order of the fields is different.

The STA may perform STA-to-AP transmission (packet 1000) when the most recent beam indicators 1102, 1206, 1308 have been signaled by the AP for this STA, such that this latest signaling has been received before its period limit expires. ) Fills the beam indicator field 1006. Alternatively, the STA populates the beam indicator field 1006 with default values as described above. For each beam indicator value, the AP recognizes which beam (antenna) the indication corresponds to, and the STA does not need to recognize this correspondence.

14 is a flowchart of a method 1400 of transmitting smart antenna information by an AP and an STA. The method 1400 begins by the AP selecting a beam for communication to the STA and selecting a beam indicator corresponding to the selected beam (step 1402). Preferably, but not necessarily, the AP selects a beam that maximizes the signal level or signal to interference ratio (SIR) at its receiver. There are various ways in which the AP can recognize which beam maximizes the SIR for a particular STA.

For example, when receiving a packet predicted from a particular STA, different beams may be tried, and the beam that produces the optimal quality of the received signal may be selected. Examples of predicted packets include ACK after transmission of the data packet to a specific STA, and CTS after transmission of the RTS packet to a specific STA. Using the predicted packet, the STA may not need to add the beam indicator field 1006 after the PLCP header 1004 since the packet is predicted to the AP to be transmitted by a particular STA, so that the AP may You already know if you want to use.

The AP then sends beam indicator information to the STA (step 1404). The beam indicator information (as described in more detail above) includes an optional time limit for the expiration of the beam indicator, the AP address, the STA address, and the beam indicator information. The method 1400 assumes that there is a time limit in the beam indicator information.

The STA determines whether the period limit of the beam indicator information has been reached, that is, whether the beam indicator information is still valid (step 1406). If the time limit has not been reached, the STA sets a beam indicator such that the packet is sent to the selected beam (step 1408). The STA transmits a packet with beam indicator information to the selected beam (step 1410). The AP initiates receiving a packet from the STA on the omni-directional beam (step 1412). The AP decodes the beam indicator information included in the packet and switches the antenna to the selected beam to receive the remaining packet (step 1414). The method then ends (step 1416).

If the period limit of the beam indicator information is reached, i.e., the beam indicator information is no longer valid (step 1406), the STA sets the beam indicator so that the packet is sent in the omni-directional beam (or pattern) (step 1420). ). The STA then sends a packet on the omni-directional beam (step 1422). The AP receives a packet on the omni-directional beam (step 1424) and the method ends (step 1416). Since the packet is being transmitted on the omni-directional beam (either because the packet from the STA does not contain beam indicator information or the STA sets the beam indicator to a reference value), the AP does not need to change the antenna beam.

15 illustrates an example of a method 1400. In one example, assume that the AP 1500 has already determined that the optimal beams to communicate with STA 1 1502 and STA 2 1504 (as shown in FIG. 9) are b ₁ and b ₂ , respectively.

15 illustrates a sequence of possible events in which STA 1 1502, STA 2 1504, and AP 1500 communicate with each other. First, the AP wishes to send a packet to STA 1. After gaining access to the medium (step 1510), with the beam indicator (b ₁ ) and the time limit (5 seconds) for the use of such a beam indicator, the AP switches to beam b ₁ (step 1512) and the beam indicator message The data packet is transmitted to the STA 1 including the step (step 1514). STA 1 then sends an ACK to the AP (step 1516). From this point in time (and from 5 seconds to this point), STA 1 should set the beam indicator field 1006 to b ₁ if it needs to send a packet 1000 (shown in FIG. 10) to the AP (step 1518). . After receiving the ACK from STA 1, the AP switches its antenna to the omni-directional pattern b ₀ (step 1520).

Next, the AP regains access to the medium (step 1522) and, with a beam indicator b ₂ and a time limit (5 seconds) for the use of such a beam indicator (step 1526), includes the beam indicator message. in order to transmit a packet to STA 2 switches the beam b ₂ (step 1524). STA 2 then sends an ACK to the AP (step 1528). STA 2 recognizes that the beam indicator field 1006 should be set to b ₂ for any packet transmitting to the AP (other than ACK or CTS) up to 5 seconds from this point in time. After receiving the ACK from STA 2, the AP switches its antenna to the omni-directional pattern b ₀ (step 1532).

STA 1 then obtains access to the medium (step 1534) and sets the beam indicator field 1006 to b ₁ (assuming less than 5 seconds has elapsed) and sends a data packet to the AP (step 1536). After decoding the beam indicator field, the AP immediately switches to beam b ₁ to decode the remaining packets (step 1540). After the end of packet reception, the AP sends an ACK to STA 1 (step 1542) and switches this antenna to the omni-directional pattern b ₀ (step 1544).

STA 2 then obtains access to the medium (step 1546) and sets the beam indicator field 1006 to b ₂ to transmit to the AP in the data packet (assuming less than 5 seconds have elapsed; 1548). After decoding the beam indicator field, the AP immediately switches the beam b ₂ to decode the remaining packets (step 1552). After the end of packet reception, the AP sends an ACK to STA 1 (step 1554) and switches the antenna to the omni-directional pattern b ₀ (step 1556).

If the time limit of the beam indicator information has expired (5 seconds in this example), the STA (STA 1 or STA 2) may set the beam indicator field 1006 to b ₀ (reference value).

The present invention makes it possible to use a smart antenna in an AP without causing any major inconvenience. Since the number of possible beams can usually be limited to eight or less (eg, 3 or 4 bits for the beam indicator field), the addition of the beam indicator field to the PLCP header does not cause excess overhead.

For the purpose of backward compatibility, since the field of the PLCP header may be provided with a new value for a packet transmitted from the STA implementing the present invention, the AP determines whether an incoming packet was sent from the STA implementing the present invention. can do. For example, one of the currently reserved bits in the "service field" of the PLCP header may be used to indicate whether the STA implements the present invention (and therefore there is a beam indicator field after the PLCP header). Otherwise, the AP recognizes that it should not predict the beam indicator field after the PLCP header and can simply use the omni-directional pattern to decode the remaining packets.

The invention also applies to the case of a mesh architecture where the mesh node is likely to receive packets from one or more mesh nodes. In this case, the mesh node plays the role of the STA and the AP as described above. This means that the mesh indicator A uses the beam indicator field when the mesh node A transmits to another mesh node B using the value of the beam indicator previously signaling to the mesh node A. Conversely, mesh node A uses the value of the beam indicator previously signaled to mesh node B, so mesh node B uses the beam indicator field when transmitting to mesh node A.

As an alternative to having a beam indicator field after the PLCP header, the STA may add its address after the PLCP header. This is not an efficient solution because the STA address is 48 bits long compared to 3 or 4 bits for the beam indicator. Another alternative is to replace the beam indicator field with any STA index assigned by the AP to the STA upon combining and / or higher layer signaling. The STA index may be relatively short (less than 10 bits at the maximum value) depending on the maximum value of the associated STA. The AP may observe and use the current optimal beam with respect to the STA index defined in the preamble. The AP may not need to signal the beam indicator to the STA in every AP to STA packet, but may be more additional bits after the PLCP preamble.

Antenna performance information

As used in the beacon frame, the performance information field 1600, the join request frame, the join response frame, and the probe response frame have some reserved bits as shown in FIG. The performance information field 1600 includes an extended service set (ESS) subfield 1602, an IBSS subfield 1604, a contention free (CF) pollable subfield 1606, a CF polling request subfield 1608, a privacy sub Field 1610, and a number of reserved bits 1612. In the 802.11 standard, subfields 1602 through 1610 are each one bit long and there are eleven reserved bits 1612.

The present invention uses one of the reserved bits 1612 for transmitting antenna performance information by using one of the reserved bits as a flag indicating whether antenna performance information can be transmitted. Details of antenna performance are part of an additional IE, which is attached to the end of the packet when the antenna performance information flag is set.

The antenna performance information IE may be included as part of a joint request frame, a joint response frame, a probe request frame, and a probe response frame. An example of a portion of a join request frame 200 that includes this new IE is shown in FIG. 17. The frame 1700 includes a performance information field 1702, a listening interval field 1704, an SSID IE 1706, a supported rate IE 1708, and an antenna performance IE 1710. Alternatively, antenna performance IE 1710 may be added to any management frame, such as a recombination request, recombination response, or beacon, or to any control frame, or to a data packet. In a preferred embodiment, antenna performance IE 1710 is transmitted in a management frame. When the antenna capability IE 1710 is added to the probe request frame and the probe response frame, the STA may use this information before initiating the joining procedure with the AP.

Antenna performance IE 1710 is shown in detail in FIG. 18, with antenna description field 1802, multiple supported beam fields 1804, field 1806 indicating support of transmit antenna information after PLCP, and diversity description field. 1808, a field 1810 indicating support of antenna measurement signaling, and a field 1812 indicating support for multiple inputs 1812. Additional antenna performance information may also be included in the IE 1710.

In one embodiment, the minimum amount of information to be exchanged includes an antenna description field 1802, and the remaining fields may be optional. If the antenna technology type is known, the remaining fields (ie, fields 1804-1812) can be derived.

After one side (AP or STA) receives antenna performance information from the transmitting side, the receiving side transmits and / or receives, such as the number of antennas used, diversity method, smart antenna technology used for transmission and reception, and additional antenna measurements. Adjust local settings for.

If the receiving side cannot support the antenna performance of the transmitting side, the transmitting side may not be able to use certain antenna characteristics. Certain antenna techniques can work properly only if the transmitting and receiving sides can use them. One example is MIMO technology, which only works if supported on both sides.

19 illustrates a method 1900 for exchanging antenna performance information. For the purpose of describing this method 1900, the terms "transmitting STA" and "receiving STA" are used. Both the transmitting STA and the receiving STA may be APs or STAs so that the exchange of antenna performance information may occur in any direction between the AP and the STA or the two STAs.

The method 1900 begins with the transmitting STA transmitting its antenna capability information to the receiving STA in the antenna capability IE (step 1902). The receiving STA receives the antenna capability IE (step 1904) and determines whether it can support the requested antenna capability. If the receiving STA can support the antenna performance of the transmitting STA (step 1906), the receiving STA adjusts its setting to process the antenna performance of the receiving STA (step 1908). The receiving STA sends an acknowledgment of its antenna performance to the transmitting STA (step 1910).

In another embodiment of the method 1900, an acknowledgment is sent to the transmitting STA before the receiving STA adjusts its settings (ie, steps 1908 and 1910 switch). If this message is an acknowledgment of the antenna performance of the receiving STA, it does not need to be an ACK signal. If the receiving STA has some, but not all, of the transmitting STA's, a combination of capabilities may occur to achieve a common set of capabilities to be used. In a preferred embodiment, this capability may be a smaller set of capabilities belonging to both STAs.

The transmitting STA initiates transmission using the communicated antenna capabilities (step 1912) and the method ends (step 1914).

If the receiving STA does not support the antenna performance of the transmitting STA (step 1906), the receiving STA notifies the transmitting STA that it does not have the requested antenna capability (step 1916). The transmitting STA initiates transmission using the requested antenna capability (step 1918) and the method ends (step 1914).

20 is a flowchart of another method 2000 for exchanging antenna performance information between a transmitting STA 2002 and a receiving STA 2004. The transmitting STA 2002 transmits its antenna performance information to the receiving STA 2004 (step 2010). The receiving STA 2004 transmits its antenna performance information to the transmitting STA 2002 (step 2012). Step 2010 and step 2012 may be performed in reverse order. Steps 2010 and 2012 are not important when antenna performance information is received between the transmitting STA 2002 and the receiving STA 2004. Optionally, the transmitting STA 2002 and the receiving STA 2004 may combine antenna capabilities to discover a common antenna capability set or exchange measurement information (step 2014). This optional step can be used to refine the antenna specific set to be used.

After the exchange of antenna information (step 2010, 2012) and any further information exchange (step 2014), both the transmitting STA 2002 and the receiving STA 2004 locally determine which antenna characteristics to use based on locally supported antenna performance. (Step 2016, 2018).

Although the transmission of antenna performance information is represented by WLAN, the principles of the present concept are equally applicable to any type of wireless communication system.

System implementation

21 is a block diagram of a system 2100 configured to implement various aspects of the present invention. System 2100 includes an AP 2102 and a STA 2104. The AP 2102 includes an antenna performance determination device 2110 that determines antenna performance of the AP 2102 by examining antenna performance information stored in the antenna performance information device 2112 connected to the antenna performance determination device 2110. . The antenna performance of the AP 2102 is transmitted by a transceiver 2114 connected to the antenna performance determining apparatus 2110 and an antenna 2116 connected to the transceiver 2114. The beam switching device 2118 is connected to the transceiver 2114 and used to switch the beam of the antenna 2116.

The STA 2104 receives antenna performance information of the AP 2102 through the antenna 2120 and the transceiver 2122 connected to the antenna 2120. The antenna performance determining device 2124 is connected to the transceiver 2122 and accesses the antenna performance information device 2126 connected to the antenna performance determining device 2124 to obtain the antenna performance of the AP 2102 from the antenna of the STA 2104. Compare with performance information. The antenna performance determining apparatus 2124 is connected to the STA setting adjusting apparatus 2128, which adjusts the setting of the STA 2104 to use the smart antenna performance.

The combination of antenna performance between the AP 2102 and the STA 2104 may occur through the individual antenna performance determination apparatus 2110, 2124. Although system 2100 has been described using AP 2102, AP 2102 may be another STA in system 2100.

Example

A method of implementing a smart antenna when establishing a bond between an STA and an AP includes: (a) transmitting a beacon frame by an AP on one antenna beam; (b) receiving a beacon frame at the STA; (c) measuring a signal quality of the beacon frame at the STA; (d) switching to different antenna beams; (e) repeating steps (a) through (d) until the beacon frame is transmitted on all antenna beams; And (f) coupling the STA to the AP transmitting the beacon frame having the highest signal quality in one of the antenna beams.

A method of implementing a smart antenna when establishing a bond between an STA and an AP includes: (a) transmitting a probe request frame from the STA to the AP, wherein the probe request frame determines whether the STA wants to scan multiple beams from the AP. Contains an indication of-; (b) transmitting a probe response frame from the AP to the STA on one antenna beam; (c) receiving a probe response frame at the STA; (d) measuring signal quality of the probe response frame at the STA; (e) switching to different antenna beams; (f) repeating steps (b) through (e) until the probe response frame is transmitted on all antenna beams; And (g) coupling the STA to the AP transmitting the beacon frame having the highest signal quality in one of the antenna beams.

The method according to one of the two paragraphs above, waits for a section before and after switching the antenna beam to beacon frame, the section being larger than the short inter-frame space and distributed inter frame. less than -frame space).

System for implementing a smart antenna including a beacon frame transmitted from the AP to the STA when establishing the association between the STA and the AP.

A system for implementing a smart antenna for establishing a bond between a STA and an AP, the system comprising: a probe request frame transmitted from an STA to an AP, wherein the probe request frame is used to determine whether the STA wants to scan multiple antenna beams from the AP. Contains an indication-; And a probe response frame sent from the AP to the STA.

In any one of the previous embodiments, the beacon frame or probe response frame includes a field identifying the total number of antenna beams and / or a field identifying the current antenna beam.

A method of supporting the use of a smart antenna in a WLAN including an AP and a STA includes selecting an antenna beam by the AP for use in communication with the STA; Transmitting the selected beam information from the AP to the STA; And transmitting a packet from an STA to the AP, the packet including the selected beam information, wherein the AP receives at least a portion of the packet using the selected beam.

In the method according to the previous paragraph, the selecting step includes selecting an antenna beam having a maximum signal level or an antenna beam having a maximum signal to interference ratio.

A method according to one of the previous two paragraphs, wherein the transmitting step comprises: a beam indicator; Period limitation for the beam indicator, wherein the selected beam can only be used if the period limitation has not expired; A media access control (MAC) address of the AP; And transmitting at least one of the STA's MAC address.

In a method according to one of the previous three paragraphs, the transmitting step comprises transmitting the selected beam information in a separate message.

In a method according to one of the previous four paragraphs, the transmitting step includes transmitting the selected beam information as part of an existing frame type.

In a method according to one of the previous five paragraphs, the transmitting step further comprises transmitting a beam indicator information flag to indicate the presence of the selected beam information within the frame.

The method according to one of the preceding six paragraphs, wherein the transmitting step comprises switching an antenna of the AP to the selected beam prior to the transmission of the selected beam information.

The method according to one of the previous seven paragraphs, wherein the transmitting step further comprises switching the antenna of the AP in an omni-directional pattern after transmitting the selected beam information on the selected beam.

The method according to one of the previous eight paragraphs further comprises sending an acknowledgment from the STA to the AP upon successful reception of the selected beam information.

The method according to one of the previous nine paragraphs comprises: receiving a first portion of a packet at an AP via an omni-directional beam, the first portion of the packet including selected beam information; Switching the antenna of the AP to the selected beam as defined in the selected beam information; And receiving a second portion of the packet at the AP via the selected beam.

The method according to one of the previous ten paragraphs, wherein the switching comprises decoding the first portion of the packet to determine the selected beam.

A system supporting the use of a smart antenna in a WLAN comprising an AP and an STA, the system comprising: a first packet transmitted from the AP to the STA, wherein the first packet is the selected beam indicator, the AP's Medium Access Control (MAC) An address, and a MAC address of the STA, wherein the selected beam indicator identifies the antenna beam selected by the AP for use for communication with the STA; And a second packet transmitted from the STA to the AP, wherein the second packet includes a selected beam indicator, wherein the AP receives at least a portion of the second packet via the selected beam.

In the system according to the previous paragraph, the first packet is sent as a separate message from the AP to the STA.

In a system according to one of the previous two paragraphs, the first packet is part of an existing frame type.

In a system according to one of the previous three paragraphs, the first packet further comprises a time limit for the selected beam indicator, wherein the selected beam can only be used if the time limit has not expired.

In a system according to one of the previous four paragraphs, the first packet further includes a beam indicator information flag to indicate the presence of the selected beam indicator in the packet.

In a system according to one of the previous five paragraphs, the first portion of the second packet is received at the AP via an omni-directional beam, where the first portion of the second packet includes a selected beam indicator. Switching the antenna to the selected beam as defined in the selected beam indicator, the second portion of the second packet is received at the AP via the selected beam.

In a wireless communication system, a system for exchanging smart antenna performance information between a transmitting STA and a receiving STA is exchanged between a transmitting STA and a receiving STA before data transmission between two STAs. Contains information about the performance of the two STAs.

In the system according to the previous paragraph, the wireless communication system is a WLAN, where the transmitting STA is an AP or STA in the WLAN and the receiving STA is an STA or AP in the WLAN.

In a system according to one of the previous two paragraphs, the antenna performance information element is an antenna description field, an indicator of support of transmit antenna information after multiple supported beams, a physical layer convergence protocol header, diversity technology indicator, measurement signaling support. At least one field selected from an indicator of an indicator and an indicator of multiple input support.

In a system according to one of the previous two paragraphs, each field is derived by receiving an STA from the antenna description field.

In a system according to one of the previous three paragraphs, the antenna performance information element is transmitted as part of a management frame, control frame or data frame.

In the system according to one of the previous four paragraphs, the antenna performance information element is between the transmitting STA and the receiving STA at any point after coupling between the transmitting STA and the receiving STA or at any point after data transmission between the transmitting STA and the receiving STA. Exchanged.

A method of exchanging smart antenna performance information between a transmitting STA and a receiving STA in a wireless communication system includes: transmitting antenna performance information from a transmitting STA to a receiving STA; Determining whether the receiving STA can support antenna performance of the transmitting STA; Adjusting a setting at a receiving STA if the receiving STA can support antenna performance of the transmitting STA; And when the receiving STA can support antenna performance of the transmitting STA, transmitting data from the transmitting STA to the receiving STA using the antenna performance.

The method according to the previous paragraph further comprises responding to the transmitting STA using an acknowledgment of the antenna performance of the receiving STA.

In the method according to one of the previous two paragraphs, the response step is performed before or after the adjustment step.

In a method according to one of the previous three paragraphs, the responding step includes notifying the transmitting STA that the receiving STA does not have the requested antenna capability.

In a method according to one of the previous four paragraphs, the transmitting step includes transmitting data from the transmitting STA to the receiving STA without using antenna performance.

In a method according to one of the previous five paragraphs, the transmitting step includes transmitting antenna performance information as part of a management frame.

In the method according to one of the previous six paragraphs, the adjusting step comprises adjusting at least one setting selected from the group consisting of a plurality of used antennas, a diversity method, a smart antenna technique used, and additional antenna measurements. do.

A method of exchanging smart antenna performance information between a first STA and a second STA in a wireless communication system includes: transmitting antenna performance information from a first STA to a second STA; And transmitting antenna performance information from the second STA to the first STA.

The method according to the previous paragraph further comprises, at the first STA and the second STA, locally determining antenna performance for use for later transmission and reception between the first STA and the second STA.

In the method according to one of the previous two paragraphs, the determining step is performed without any further communication between the first STA and the second STA.

The method according to one of the previous three paragraphs further comprises comparing antenna performance of the first STA and the second STA, wherein the determining step uses antenna performance supported by both the first STA and the second STA. It includes a step.

The method according to one of the preceding four paragraphs further comprises the step of exchanging measurement information between the first STA and the second STA, wherein the exchanging step is performed before the determining step.

The method according to one of the previous five paragraphs further comprises negotiating antenna performance information between the first STA and the second STA, wherein the negotiation step is performed before the determining step.

A system for implementing smart antenna characteristics in a WLAN includes an AP and an STA. The AP includes a first antenna performance determination device; A first antenna performance information apparatus connected to a first antenna performance determination apparatus, the first antenna performance determination apparatus configured to determine antenna performance of the AP by examining information stored in the first antenna performance information apparatus; A first transceiver connected to the first antenna performance determination device; A first antenna connected to the first transceiver; And a beam switching device connected to the transceiver, the beam switching device configured to switch the beam of the first antenna. The STA may include a second antenna; A second transceiver connected to a second antenna, the second transceiver configured to receive antenna performance information from an AP; A second antenna performance determination device connected to a second transceiver; A second antenna performance information apparatus connected to a second antenna performance determination apparatus, wherein the second antenna performance determination apparatus compares the antenna performance of the STA retrieved from the second antenna performance information apparatus with the antenna performance of the AP received from the second transceiver; Configured-; And an STA setting adjusting device connected to the second antenna performance determining device, wherein the STA setting adjusting device is configured to adjust the setting of the STA to use the smart antenna performance.

In the system according to the previous paragraph, the first antenna performance determination apparatus and the second antenna performance determination apparatus are configured to negotiate a level of antenna performance that both the AP and the STA can support.

While the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element may be combined in various combinations alone (without other features and elements of the preferred embodiments) or with or without other features and elements of the present invention. Can be used as While particular embodiments of the present invention have been shown and described, many modifications and variations can be made by those skilled in the art without departing from the scope of the present invention. The above description is illustrative and does not limit the invention in any way.

According to the present invention described above, the present invention provides signaling and support for the AP to transmit its beacon on multiple beams in passive scanning, and also requests the AP to transmit a probe response to the multiple beams in active scanning. By doing so, the beam selection problem is solved for both passive scanning and active scanning, and the mesh architecture can be implemented as a mesh node, thereby solving the exchange of antenna performance information between the AP and the STA.

1 is a diagram of a WLAN showing an omni and directional antenna beam pattern.

2 shows a beacon frame format for identifying antenna beams.

3 is a timing diagram for manual scanning.

4 is a flowchart illustrating a method of transmitting a beacon frame in passive scanning.

5 is a flow diagram illustrating a probe request frame format for use in active scanning.

6 is a flow diagram illustrating a probe response frame format for use in active scanning.

7 is a timing diagram for active scanning.

8 is a flowchart illustrating a method of transmitting a probe response frame in active scanning.

9 illustrates transmission of a data packet between an AP and a STA.

FIG. 10 illustrates a frame format including beam indicator information transmitted by the STA. FIG.

11 illustrates a beam indicator message format transmitted by an AP.

12A and 12B illustrate a frame format including beam indicator information sent by an AP.

13A and 13B illustrate another frame format including beam indicator information transmitted by the AP.

14 is a flowchart illustrating a method of transmitting smart antenna information by an AP and an STA.

FIG. 15 is a flowchart showing an example of the method shown in FIG. 14; FIG.

16 shows an existing performance information field.

17 illustrates a portion of a frame including antenna performance IE.

FIG. 18 shows antenna performance IE shown in FIG. 17; FIG.

19 is a flowchart illustrating a method of exchanging antenna performance information.

20 is a flowchart illustrating another method of exchanging antenna performance information.

21 is a block diagram of a system configured to implement the present invention.

<Explanation of symbols for main parts of the drawings>

202: frame control

204: period

212: sequence control

214: timestamp field

216 beacon information field

218: performance information field

700: AA Probe Request

704: AA probe response

1002: PLCP preamble

1004: PLCP Header

1006: Beam Indicator

1008: MAC frame

1102: beam indicator

1104: AP address

1106: STA address

1108: time limit

2110: antenna performance determination device

2112: antenna performance information device

2114 transceiver

2118: beam switching device

2128: STA setting adjustment device

Claims (2)

A system for implementing smart antenna characteristics in a wireless local area network, Access point; And A smart antenna characteristic implementation system comprising a station, The access point is, A first antenna performance determination device; A first antenna performance information device, connected to the first antenna performance determination device, configured to determine antenna performance of the AP by examining information stored in the first antenna performance information device; A first transceiver connected to said first antenna performance determination device; A first antenna connected to the transceiver; And A beam switching device connected to the transceiver and configured to switch a beam of the first antenna, The station, A second antenna; A second transceiver connected to the second antenna and configured to receive antenna performance information of the AP; A second antenna performance determination device connected to the second transceiver; A second antenna performance information device, connected to the second antenna performance determination device, configured to compare antenna performance of the AP received from the second transceiver with antenna performance of the station retrieved from the second antenna performance information device; And And a station setting adjusting device connected to the second antenna performance determining device and configured to adjust the setting of the station to use smart antenna performance. The method of claim 1, And the first antenna performance determining apparatus and the second antenna performance determining apparatus are configured to negotiate a level of antenna performance that both the AP and the station can support.