CN102498678B - Method and apparatus for transmitting and receiving signal in relay station - Google Patents

Abstract

A method of a Relay Station (RS) transmitting and receiving a signal in a wireless communication system including the RS, the method comprising: receiving frame configuration information on an RS frame from a Base Station (BS); configuring, in the RS frame, a Downlink (DL) access zone in which a signal is transmitted to a relay Mobile Station (MS) connected with the RS and a DL relay zone in which a signal is received from the BS, based on the frame configuration information; comparing a time necessary for an operation to be switched from the DL access zone to the DL relay zone with a propagation delay time to receive a signal from the BS; configuring some symbols in the DL access zone or the DL relay zone as a transition time according to a result of the comparison; transmitting the signal to the relay MS in the DL access zone; and receiving the signal from the BS in the DL relay zone.

Description

Method and device for transmitting and receiving signals in a relay station

technical field

The present invention relates to a wireless communication, and more particularly, to a method for a relay station to transmit and receive signals and an apparatus for performing the method.

Background technique

The IEEE (Institute of Electrical and Electronics Engineers) 802.16e standard is the sixth for IMT (International Mobile Telecommunications)-2000 in ITU-R (ITU-Radiocommunication Sector) under the control of ITU (International Telecommunication Union) in 2007 standard and has been adopted under the name 'WMAN-OFDMATDD'. ITU-R is preparing an advanced IMT system, which is a next-generation 4G mobile communication standard since IMT-2000. At the end of 2006, the IEEE 802.16WG (Working Group) has decided to continue the IEEE 802.16m project for the purpose of writing a revised standard of the existing IEEE 802.16e which is a standard for advanced IMT systems. As can be seen from the above purpose, the IEEE 802.16m standard includes both aspects of past continuation (ie, modification of IEEE 802.16e standard) and future continuation (ie, standard for next-generation advanced IMT systems). Therefore, the IEEE 802.16m standard is required to satisfy all advanced requirements for an advanced IMT system while maintaining compatibility with a mobile WiMAX system based on the IEEE 802.16e standard.

In the case of broadband wireless communication systems, efficient transmission and reception schemes and utilization schemes have been proposed in order to maximize the efficiency of limited radio resources. One of the systems considered in the next-generation wireless communication system is an Orthogonal Frequency Division Multiplexing (OFDM) system capable of reducing Inter-Symbol Interference (ISI) using low complexity. An OFDM system converts serially input data symbols into N number of parallel data symbols and carries them on N number of separate subcarriers. The subcarriers maintain orthogonality in the frequency domain. Each of the orthogonal channels experiences uncorrelated frequency selective fading. Therefore, complexity at the receiving terminal can be reduced, the interval between transmitted symbols is extended, and ISI can be minimized.

Orthogonal Frequency Division Multiple Access (OFDMA) refers to a multiple access method for achieving multiple access by independently providing some of the available subcarriers to each user in a system using OFDM as a modulation method . In the OFDMA method, it is common that frequency resources called subcarriers are provided to individual users, and the frequency resources do not overlap with each other because they are independently provided to a plurality of users. Therefore, frequency resources are allocated exclusively to users. In an OFDMA system, frequency diversity for multiple users can be obtained through frequency selective scheduling, and subcarriers can be allocated in various ways according to an arrangement method for subcarriers. In addition, the efficiency of a spatial area can be improved through a spatial multiplexing scheme using a plurality of antennas.

Meanwhile, wireless communication systems including relay stations are being developed. A relay station (RS) operates to extend cell coverage and improve transmission performance. If a base station provides a service to a mobile station placed at the boundary of the coverage of the base station through a relay station, cell coverage can be extended. Furthermore, if the relay station improves the reliability of signal transmission between the base station and the mobile station, the amount of transmission data can be increased. Although a mobile station is placed within the cell coverage of a base station, it can use a relay station if the mobile station is placed within a shaded area.

Relay stations can be mainly divided into two types. The first type is a transparent relay station. In this type, the base station determines all information necessary for relay processing, and the transparent relay station simply relays the data received from the base station to a subordinate relay station or a mobile station. A transparent relay station uses the same carrier frequency as a superior or subordinate station. The second type is a non-transparent relay station. The non-transparent relay station directly performs resource allocation, determination of modulation and coding scheme (MCS) level, power control, etc. necessary for relay processing, and relays data. A non-transparent relay station may use the same carrier frequency as an upper or lower station or may use a different carrier frequency than that of the upper or lower station.

In the centralized scheduling mode, the base station determines the allocation of frequency bands for relay stations (RS) and relay station mobile stations (RS-MS). In the distributed scheduling mode, the RS determines the allocation of frequency bands for the RS-MS while operating in conjunction with the base station. Transparent base stations can only operate in centralized scheduling mode, while non-transparent base stations can operate in centralized or distributed scheduling mode.

Amplify and Forward (AF) and Decode and Forward (DF) can be used as a relay method of the RS. In the AF method, an RS amplifies data received from a base station and transmits the data to a mobile station (MS). In the DF method, the RS checks the destination station by decoding the data received from the base station, encodes the decoded data, and relays the encoded data to the subordinate RS or MS (i.e., the destination station) .

In a wireless communication system including such a relay station, a new frame structure different from the conventional frame structure is required. The RS can use the same frequency band for transmitting signals to the base station as the frequency band for receiving signals from the RS-MS. Alternatively, the RS can use the same frequency band for receiving signals from the base station as the frequency band for transmitting signals to the RS-MS. Due to self-interference, it is difficult for the RS to simultaneously transmit and receive signals in the same frequency band. Therefore, time for switching the operation mode between transmission and reception of signals is required. It is assumed that the RS is generally unable to transmit or receive signals during the operation mode transition time.

There are propagation delay times as well as operation mode transition times that must be considered. Propagation delay time can be thought of as the physical transit time used to transmit and receive radio signals between two communication stations. In other words, in a wireless communication system including a relay station, an RS must communicate with a base station and an MS based on a timing relationship in which an operation mode switching time, a propagation delay time, and the like are considered.

Contents of the invention

technical problem

The present invention provides a method for a relay station to transmit and receive signals in a wireless communication system including the relay station and an apparatus for performing the same.

problem solution

According to an aspect of the present invention, there is provided a method for a relay station (RS) to transmit and receive a signal in a wireless communication system including an RS, the method including: receiving frame configuration information on an RS frame from a base station (BS); based on the Frame configuration information configuring a downlink (DL) access zone in which a signal is transmitted to a relay mobile station (MS) connected to the RS and a DL relay zone in which a signal is received from the BS are configured in the RS frame; The time necessary to switch the operation from the DL access zone to the DL relay zone is compared with the propagation delay time to receive a signal from the BS; according to the result of this comparison, some of the DL access zone or the DL relay zone The symbols are configured to transition time; in the DL access zone, the signal is transmitted to the relay MS; and in the DL relay zone, the signal is received from the BS.

According to another aspect of the present invention, there is provided a method for an RS to transmit and receive a signal in a wireless communication system including an RS, the method including: receiving frame configuration information about an RS frame from a BS; An uplink (UL) access zone in which signals are received from a relay MS connected to the RS and a UL relay zone in which signals are transmitted to the BS are configured in the RS frame; receiving the signal; and in the UL relay zone, transmitting the signal to the BS. The UL access region is time-aligned with the UL access region of the BS frame, and then transmitted or transmitted before the UL access region of the BS frame at almost a specific time interval.

According to still another aspect of the present invention, there is provided a method for an RS to transmit and receive a signal in a wireless communication system including an RS, the method including: receiving frame configuration information about an RS frame from a BS; Configured that the frame includes a DL access zone where a signal is transmitted to a relay MS connected to the RS, a DL relay zone where a signal is received from the BS, a DL relay zone where a signal is received from a relay MS connected to the RS The UL access zone of the signal and the UL relay zone in which the signal is transmitted to the BS; configure the switching time in the DL access zone or the UL relay zone; transmit the signal in the DL access zone or the UL relay zone, and in Signals are received in the DL relay zone or UL access zone.

Beneficial effects of the present invention

The RS can perform communication with the BS or the relay MS by considering an operation switching time between a reception mode and a transmission mode and a transmission delay time required for transmitting and receiving signals. Therefore, even without greatly changing the frame structure between the existing BS and the existing macro MS, it is possible to perform communication with the RS included in the wireless communication system.

Description of drawings

FIG. 1 is a diagram showing a wireless communication system including a relay station;

FIG. 2 is a diagram showing an example of a superframe structure;

FIG. 3 is a diagram showing an example of a TDD frame structure;

FIG. 4 is a diagram showing an example of an FDD frame structure;

FIG. 5 is a diagram showing an example of a frame structure;

6 is a diagram showing an example of a frame structure that can be used in a wireless communication system including a relay station;

7 is a diagram conceptually illustrating a frame structure to which a method for transmitting and receiving signals by a relay station according to an embodiment of the present invention is applied;

FIG. 8 is a diagram showing a TDD frame structure;

FIG. 9 is a diagram showing an example of a TDD frame structure;

FIG. 10 is a diagram showing an FDD DL frame structure;

FIG. 11 is a diagram showing an FDD UL frame structure;

FIG. 12 is a diagram showing an example including a transition time in an FDD frame; and

FIG. 13 is a diagram showing the structures of a relay station and a base station.

Detailed ways

The following techniques can be used in various radio communication systems such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), and Single Carrier Frequency Division Multiple Access (SC-FDMA). A CDMA system can be implemented using a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented using radio technologies such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS) or Enhanced Data rates for GSM Evolution (EDGE). The OFDMA system can be implemented using a radio technology such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, or Evolved UTRA (E-UTRA). IEEE 802.16m is an evolution of IEEE 802.16e, and it provides backward compatibility with IEEE 802.16e-based systems. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UTMS (E-UMTS) using Evolved UMTS Terrestrial Radio Access (E-UTRA). 3GPP LTE employs OFDMA in the downlink and SC-FDMA in the uplink. LTE-A (Advanced) is an evolution of 3GPP LTE.

To clarify the description, the IEEE 802.16m system is mainly described, but the technical features of the present invention are not limited thereto.

FIG. 1 is a diagram showing a wireless communication system including a relay station (hereinafter referred to as RS).

Referring to FIG. 1, a wireless communication system 10 including an RS includes at least one base station (hereinafter referred to as BS). The BS 11 provides communication services to a geographical area 15 commonly referred to as a cell. A cell can be divided into multiple areas. Each of the areas is called a sector. One or more cells can exist in one BS. In general, BS 11 refers to a fixed station that communicates with a mobile station (hereinafter referred to as MS) 13, and it can also be referred to as another technology such as evolved NodeB (eNB), base transceiver system ( BTS), access point (AP), access network (AN), or advanced base station (ABS). BS 11 is capable of performing functions such as connectivity, management, control, and resource allocation between RS 12 and MS 14.

The RS 12 refers to a device for relaying signals between the BS 11 and the MS 14, and it can also be referred to as another technology such as a relay node (RN), a repeater, or an advanced relay station (ARS). Any method including amplify and forward (AF) and decode and forward (DF) can be used as the relay method used by the RS, but the technical features of the present invention are not limited thereto.

MS 13 and 14 can be fixed and mobile, and can also be referred to as another technology, such as Advanced Mobile Station (AMS), User Terminal (UT), Subscriber Station (SS), wireless device, personal digital assistant ( PDA), wireless modem, handheld device, access terminal (AT) or user equipment (UE). Hereinafter, a macro MS refers to an MS that directly communicates with the BS 11, and a relay MS (RS-MS) refers to an MS that communicates with the RS. The macro MS 13 within the cell of the BS 11 can also communicate with the BS 11 via the RS 12 in order to increase the transmission rate according to the diversity effect.

It is assumed in the following that downlink (DL) refers to communication from the BS 11 to the macro MS 13, and uplink (UL) refers to communication from the macro MS 13 to the BS 11.

FIG. 2 is a diagram showing an example of a superframe structure.

A superframe (SF) includes a superframe header (SFH) and 4 frames F0, F1, F2 and F3. Frames within a superframe can have the same length. The size of each superframe may be 20ms and the size of each frame may be 5ms, but are not limited thereto. The length of a superframe, the number of frames included in a superframe, the number of subframes included in each frame, and the like can be modified in various ways. The number of subframes in a frame can be changed in various ways according to channel bandwidth, length of cyclic prefix (CP), or both.

The superframe header can carry important system parameters and system configuration information. A superframe header can be placed within the first subframe of the superframe. A superframe header can be classified into a primary SFH (P-SFH) and a secondary SFH (S-SFH). P-SFH and S-SFH can be transmitted every superframe.

One frame includes a plurality of subframes SF0, SF1, SF2, SF3, SF4, SF5, SF6, and SF7. Each of the subframes can be used for UL or DL transmission. One subframe includes a plurality of OFDM (Orthogonal Frequency Division Multiplexing) symbols in the time domain and a plurality of subcarriers in the frequency domain. According to a multiple access method, an OFDM symbol is used to represent one symbol period and can be called another technique such as an OFDMA symbol or an SC-FDMA symbol. A subframe can consist of 5, 6, 7 or 9 OFDM symbols, but this is illustrative only. The number of OFDM symbols included in a subframe is not limited. The number of OFDM symbols included in a subframe can be changed in various ways according to a channel bandwidth or a length of a CP or both. The type of subframe can be defined according to the number of OFDM symbols included in the subframe. For example, it can be defined that a type-1 subframe includes 6 OFDM symbols, a type-2 subframe includes 7 OFDM symbols, a type-3 subframe includes 5 OFDM symbols, and a type-4 subframe includes 9 OFDM symbols symbol. One frame can include subframes having the same type. In an alternative example, one frame can include subframes with different types. That is, the number of OFDM symbols included in each of subframes within one frame may be the same or different. In an alternative example, the number of OFDM symbols included in at least one of subframes in one frame can be different from the number of OFDM symbols included in the remaining subframes.

A time division duplex (TDD) method or a frequency division duplex (FDD) method can be applied to the frame. In the TDD method, subframes are used for UL transmission or DL transmission at different times in the same frequency. That is, subframes within a TDD frame of the TDD method are classified into UL subframes and DL subframes in the time domain. Subframes within an FDD frame of the FDD method are used for UL transmission or DL transmission at different frequencies at the same time. That is, subframes within an FDD frame are classified into UL subframes or DL subframes in the frequency domain. UL transmission and DL transmission occupy different frequency bands, and they can be performed at different times.

One OFDM symbol includes a plurality of subcarriers in the frequency domain, and the number of subcarriers is determined according to the size of the FFT. There are several types of subcarriers. Types of subcarriers can be classified into data subcarriers for data transmission, pilot subcarriers for various estimations, null carriers for guard bands, and DC carriers. Parameters for characterizing OFDM symbols include BW, N _used , n, G, etc. BW is the nominal channel bandwidth. N _used is the number of used subcarriers (including DC subcarriers). '' is the sampling factor. This parameter is combined with BW and N _used , which is also used to determine the subcarrier spacing and useful symbol time. G is the ratio of CP time to useful time.

Table 1 below shows OFDMA parameters.

[Table 1]

In Table 1, _NFFT is the smallest power of 2 greater than N _used , F _s =layer (n·BW/8000)×8000, subcarrier spacing Δf=F _s /N _FFT , useful symbol time T _b =1/Δf, CP time T _g =G·T _b , OFDMA symbol time T _s =T _b +T _g , and sampling time is T _b /N _FFT .

FIG. 3 is a diagram showing an example of a TDD frame structure. This figure shows the case where G is 1/8. A 20ms superframe consists of 4 frames F0, F1, F2 and F3 in length, each frame having a length of 5ms. One frame is composed of 8 subframes SF0, SF1, SF2, SF3, SF4, SF5, SF6 and SF7, and the ratio of DL subframes to UL subframes is 5:3. The TDD frame structure in FIG. 3 can be applied to the case where the bandwidth is 5 MHz, 10 MHz or 20 MHz. Subframe SF4 (ie, the last DL subframe) includes 5 OFDM symbols, and each of the remaining subframes includes 6 OFDM symbols.

FIG. 4 is a diagram showing an example of an FDD frame structure. This figure shows the case where G is 1/8. A 20ms superframe consists of 4 frames F0, F1, F2 and F3 in length, each frame having a length of 5ms. One frame is composed of 8 subframes SF0, SF1, SF2, SF3, SF4, SF5, SF6 and SF7. All subframes include a DL zone and a UL zone. The FDD frame structure of FIG. 4 can be applied to the case where the bandwidth is 5 MHz, 10 MHz or 20 MHz.

FIG. 5 is a diagram showing an example of a frame structure. This figure shows the case where G is 1/16. The frame structure of FIG. 5 can be applied to both the FDD system and the TDD system. A frame includes 8 subframes SF0, SF1, SF2, SF3, SF4, SF5, SF6, and SF7, and the ratio of DL subframes to UL subframes may be 5:3 in a TDD system. The frame structure in FIG. 5 can be applied to the case where the bandwidth is 5 MHz, 10 MHz or 20 MHz. Each of the subframes may have 6 or 7 OFDM symbols.

FIG. 6 is a diagram showing an example of a frame structure usable in a wireless communication system including RSs.

In a wireless communication system including an RS, the RS can use the same OFDMA parameters as the BS (refer to Table 1). In addition, as shown in FIG. 6, the superframe structure of the RS can be the same as that of the BS. The superframe of the BS and the superframe of the RS can be time aligned, and they can have the same number of frames and subframes. Each of all superframes of the RS can include a superframe header, and the superframe header transmitted by the RS can have the same time position and format as the superframe header transmitted by the BS. In addition, preambles (eg, SA-preamble and PA-preamble) transmitted by the RS can be synchronized with preambles transmitted by the BS and then transmitted.

The RS requires a radio resource region in which signals can be transmitted to a relay MS (RS-MS) in downlink because it has to transmit its own DL control information (eg, preamble or superframe header (SFH)). In addition, the RS needs a radio resource region in which a signal can be transmitted to the BS in uplink because it has to receive a signal from the relay MS, decode the signal, and retransmit the decoded signal to the BS. In addition, the RS transmits a signal to the relay MS or receives a signal from the BS within the same frequency band. Alternatively, the RS receives signals from the relay MS or transmits signals to the BS within the same frequency band. Therefore, when operations for transmitting and receiving signals are switched, the RS requires an operation switching time for stable operation. In general, it is assumed that the RS does not receive or transmit signals during the operation switching time.

In addition, the RS receives a signal transmitted by the BS or the relay MS after a propagation delay time. Likewise, a signal transmitted by an RS is received by a BS or a relay MS after a propagation delay time.

That is, the frame applied to the RS must consider the operation switching time and the propagation delay time. The frame structure and the method of transmitting frames to be described later can be applied to 2-hop RSs (ie, RSs in the BS-RS-MS structure) or 3-hop RSs (ie, RSs in the BS-RS1-MS structure) from among opaque RSs. RS 1 and RS 2 in the RS 2-MS structure) and can also be applied to transparent RS. In addition, the frame structure and method can be applied not only to distributed scheduling but also to centralized scheduling.

First, to clarify the description, terms are defined.

In the following figures and descriptions, ABS refers to BS (ie ABS=BS), ARS refers to RS (ie ARS=RS), and AMS refers to MS (ie AMS=MS). ABS, ARS, and AMS are terms used in the IEEE 802.16m standard.

Round trip delay (RTD) refers to the round trip delay time between two communication stations. For example, in communication between the RS and the BS (ie, the upper station of the RS), the RTD may be the sum of the time the BS takes to receive a signal transmitted by the RS and the time the RS takes to receive a signal transmitted by the BS. From the perspective of the RS, the RTD can include the round-trip delay time for communicating with the BS and the round-trip delay time for communicating with the relay MS. The RTD is indicated by ARSRTD in case of RS, ABSRTD in case of BS, and AMSRTD in case of MS. Thus, 1/2RTD can refer to the propagation delay time from a station on one side to a station on the other side.

The transmit/receive transition gap (TTG) refers to the minimum value of the time interval required between the time point at which a signal is transmitted and the time point at which a signal is received in a case where a signal is transmitted and the signal is received. ARSTTG indicates TTG in an RS frame, and ABSTTG indicates TTG in a BS frame (in the following figures, ABSTTG can be simply indicated by TTG). For example, ARSTTG can be measured as the time interval from the last sampling time of the transmission burst to the first sampling time of the reception burst in the antenna port of the RS. ABSTTG can be longer than one symbol.

The reception/transmission transition interval (RTG) refers to the minimum value of the time interval required between the time point at which the signal is received and the time point at which the signal is transmitted in a case where a signal is received and the signal is transmitted. ARSRTG indicates RTG in an RS frame, and ABSRTG indicates RTG in a BS frame (in the following figures, ABSRTG may simply be indicated by RTG). For example, ARSRTG can be measured as the time interval from the last sampling time of a received burst to the first sampling time of a transmitted burst in the antenna port of the RS.

The idle time is a time for preventing inter-symbol interference (ISI), and may be included in TTG or RTG or can be given as an additional time. In case the BS frame is an FDD frame, a time interval of an idle state is included between the BS frames. Such a time interval is indicated by IdleTime. In case the RS frame is an FDD frame, a time interval of an idle state is included between the RS frames. Such a time interval is indicated by R_IdleTime. In the FDD DL frame of the RS, R_IdleTime can be equal to IdleTime. In the FDD DL frame of RS, R_IdleTime may be equal to IdleTime. In the FDD UL frame of RS, R_IdleTime can be equal to or less than IdleTime.

The following table shows an example of bandwidth, length of symbol according to length of CP, TTG/RTG, and idle time.

[Table 2]

In case the cell coverage of the BS is 5Km, RTD may be 33.3 μs, RTD/2 may be 16.7 μs, and ARSTTG or ARSRTG may be 50 μs.

In a wireless communication system including RSs, a BS frame can be divided into an access zone and a relay zone. In the BS frame, the access zone is located before the relay zone. Access zone duration and relay zone duration can be different in UL and DL. The BS can inform the RS of the zone configuration of the access zone and the relay zone.

A BS frame can include a DL access region and a DL transmission region. A DL access zone refers to a radio resource zone in which a BS transmits a signal to a macro MS. A DL transmission zone refers to a radio resource zone in which a BS transmits a signal to an RS or a macro MS or both. The BS frame can also include a UL access zone and a UL reception zone. A UL access zone refers to a radio resource zone in which a BS receives a signal from a macro MS. A UL reception zone refers to a radio resource zone in which a BS receives a signal from a macro MS or RS or both.

The RS frame can include a DL access zone, a DL reception zone, a UL access zone, and a UL transmission zone. A DL access zone refers to a radio resource zone in which an RS transmits a signal to a relay MS. A DL reception area refers to a radio resource area in which an RS receives a signal from a BS. A UL access zone refers to a radio resource zone where an RS receives a signal from a relay MS. A UL transmission zone refers to a radio resource zone in which an RS transmits a signal to a BS.

In the following figures, a DL reception area or a DL transmission area can also be called a DL relay area. A UL transmission zone or a UL reception zone can also be called a UL relay zone. The BS or RS can inform the MS of the locations of the DL relay zone and the UL relay zone. The RS can maintain long TTI allocations in downlink or uplink, over the entire access zone or relay zone.

Hereinafter, a method for the RS to transmit and receive signals is described based on the above terms.

The RS receives frame configuration information on the RS frame from the BS, and configures the RS frame based on the frame configuration information. The frame configuration information can include information on a radio resource region in which communication with a relay MS is performed and information on a radio resource region in which communication with a BS is performed in an RS frame. The frame configuration information can also include information on the type of frame and parameters of OFDMA. The BS can transmit frame configuration information, and the frame configuration information is included in DL control information. For example, frame configuration information can be broadcast or multicast, and the frame configuration information is included in the SF header. In this case, frame configuration information can be applied to multiple frames. A method in which the RS transmits and receives a signal using the RS frame configured based on the frame configuration information is described in detail later. The RS transmits signals to or receives signals from the relay MS or BS using the configured RS frame structure.

FIG. 7 is a diagram conceptually illustrating a frame structure to which a method of transmitting and receiving a signal by an RS according to an embodiment of the present invention is applied.

It is assumed that a BS and an RS perform time alignment between a BS frame and an RS frame and transmit signals. In this case, the RS frame structure is called a time-aligned frame. For convenience, it is also assumed that ARSRTD is equal to AMSRTD.

In the DL access zone, the BS (ABS) transmits signals to the macro MS (i.e., the AMS served by the ABS), and in the DL access zone, the RS (ARS) transmits the signal to the relay MS (i.e., the AMS served by the ABS). AMS for ARS services). For convenience, it is assumed that a propagation delay time for a macro MS to receive a signal is equal to a propagation delay time for a relay MS to receive a signal. Macro MS and relay MS receive signals after 1/2AMSRTD.

In the DL access region of the RS frame, after transmitting the signal to the relay MS, the RS receives the signal from the BS in the DL reception region (ie, the DL relay region of the RS frame). Here, the RS receives a signal transmitted in the DL relay zone of the BS frame in the DL relay zone of the RS frame after 1/2 ARSRTD. The RS undergoes operation mode switching from transmission mode (ie, DL access zone) to reception mode (ie, DL relay zone) and requires as much time as ARSTTG for operation mode switching.

If 1/2ARSRTD is greater than or equal to ARSTTG, the RS has no problem in receiving a signal transmitted by the BS. However, if 1/2ARSRTD is smaller than ARSTTG, the RS may have a problem in receiving a signal transmitted by the BS. This is because a signal transmitted by a BS must sometimes be received in an operation mode switching process. In this case, for example, some or all of the first symbol of the DL relay zone in the RS frame can be configured as a transition time and no signal may be received. In this case, the transition time can be referred to as a relay transmit-to-receive transition interval (R-TTI). The term R-TTI is used to indicate that it is necessary due to the operation of the RS transmitting a signal to a relay MS and then receiving a signal from the BS. The switching time is indicated by (C) 710 in FIG. 7 . The zone indicated by (C) 710 can be greater than or equal to {Max(1/2ARSRTD, ARSTTG)−1/2ARSRTD} in the time domain, and it can correspond to a time ranging from 0 to a maximum of one symbol. That is, R-TTI may or may not be necessary.

Although not shown in FIG. 7, the transition time may be included in the DL access region of the RS frame. For example, the last symbol of the DL access zone can be used as the transition time. Here, the RS can transmit a signal to the relay MS using symbols other than the last symbol in the DL access zone.

If the RS transmits the DL access area as much as Max(1/2ARSRTD, ARSTTG) or more than Max(1/2ARSRTD, ARSTTG) in advance, without time aligning the DL access area with the BS's DL access area, It is then possible to prevent the use of additional symbols for the transition time in the DL access zone and the DL relay zone in the RS frame. As described above, an RS frame that has been temporarily shifted is called a time-shifted frame. A method in which the RS transmits and receives a signal using the time-shifted frame and the time-aligned frame is described in detail later.

The RS receives signals from the relay MS in the placed UL access zone after the DL relay zone of the RS frame. In this case, the RS continues to operate in reception mode (in the DL relay zone and in the UL access zone), and operation mode transition time may not be required. Accordingly, the UL access zone can be successively placed into the DL relay zone. It is shown in option 1 of FIG. 7 .

Assume the method of option 1 is used. That is, in the case where the UL access zone is successively placed to the DL relay zone, the relay MS served by the RS must transmit a signal before 1/2 AM SRTD based on the UL access zone of the RS frame. In this case, the DL relay zone of the RS can overlap with the UL access zone of the relay MS, which can act as interference.

If the RS is sought to transmit a signal to the BS in the UL relay zone after receiving the signal in the UL access zone, it takes time ARSRTG. If the RS transmits a signal in the UL relay zone of the RS frame, the BS receives the signal after 1/2 ARSRTD. Therefore, from the viewpoint of the BS, the time required between the DL frame region and the UL frame region is 1/2ARSRTD+ARSRTG+1/2ARSRTD=ARSRTD+ARSRTG.

In the RS frame, the UL access zone can be configured such that it is received after 1/2 AMSRTD or later based on the DL relay zone. This is shown as option 2 in FIG. 7 . In case of option 2, the UL access zone can be configured such that the relay MS can transmit a signal after 1/2 AM SRTD or later than in option 1. If an RS transmission signal is sought in the UL relay zone after receiving the signal in the UL access zone, it takes time ARSRTD. If the time interval between the UL access zone and the UL relay zone of the RS frame is greater than or equal to ARSRTD, the RS has no problem in receiving signals transmitted by the relay MS. However, if the time interval between the UL access region and the UL relay region of the RS frame is less than the ARSRTD, the RS may have a problem in receiving a signal transmitted by the relay MS. This is because the RS may be forced to receive a signal transmitted by the relay MS in the operation mode switching process. In this case, for example, some or all of the last symbols of the UL access region of the RS frame can be configured as a transition time, and the signal may not be received. In this case, the transition time can be referred to as the Relay-to-Transmit Transition Interval (R-RTI). The term R-RTI is used to indicate that it is necessary due to the operation of the RS to receive a signal from a relay MS and then transmit the signal to the BS. This switching time is indicated by (R) 711 in FIG. 7 . In the time domain, the zone indicated by the transition time can be greater than or equal to 1/2 AMSRTD, and it can correspond to as much time as the maximum value of one symbol.

If an RS transmission signal is sought in the UL relay zone, the BS receives the signal after 1/2 ARSRTD. Therefore, from the standpoint of the BS, in case of option 2, the time required between the DL frame region and the UL frame region may be 1/2ARSRTD+1/2AMSRTD+ARSRTG+1/2ARSRTD.

In options 1 and 2, if from the standpoint of the BS, the time required between the DL frame section and the UL frame section is greater than the TTG of the BS frame, the RS has to use some symbols for switching the time.

FIG. 8 is a diagram showing a TDD frame structure.

In FIG. 8, it is assumed that all stations have the same propagation delay time of 1/2RTD for convenience. In the case that ARSTTG is less than or equal to 1/2RTD, the DL frame structure of the RS is the same as that of the BS. However, if ARSTTG is greater than 1/2RTD, then two options are possible. According to the first option, in the DL subframe of the RS frame, some symbols can be used as switching time. The symbol used as the transition time can be used for a time interval of (ARSTTG-1/2RTD).

According to the second option, if (RTG+1/2RTD) is temporally longer than (ARSTTG-1/2RTD), then the DL access region of the RS frame precedes the DL access region of the BS frame by (ARSTTG-1/2RTD) to launch. That is, a time-shifted frame structure is used. Here, the RTG is placed between the UL relay zone of frame (n-1) of the BS and the DL access zone of frame n of the BS. If the value of (RTG+1/2RTD) is greater than the value of (ARSTTG-1/2RTD), the synchronization between frames is not affected, although the RS advances the transmission of the DL access zone by a value of (ARSTTG-1/2RTD). Generally speaking, ARSTTG is longer than 1/2RTD. Also, (RTG+1/2RTD) is longer than (ARSTTG-1/2RTD) in most frame structures.

If (ARSRTG+RTD) is less than or equal to TTG, the UL access zone of the RS can be received after the elapse of 1/2RTD from the DL relay zone. If (ARSRTG+RTD) is greater than TTG, the UL access zone is received after the elapse of ½ RTD since the DL relay zone was received, but some symbols of the UL access zone may have to be used for transition time. The time necessary for the transition time can be represented by (TTG-ARSRTG-RTD), and one symbol can be used as the transition time. In general, assuming that the serving BS has a cell coverage of 5 km, (ARSRTG+RTD) is less than or equal to TTG. This is suitable for most cases except the case of 1/16CP in 5, 10 and 20MHz. Also, in most cases except the case of 1/4CP in 8.75 MHz, (1/2RTD+idle time) is greater than (ARSTTG−1/2RTD).

In the above description, the switching time (ie, R-TTI or R-RTI) can be expressed using the following equation. First, the TDD frame of the RS is described below.

In the TDD frame of the RS, R-TTI (Relay Transmit to Receive Transition Interval) can be included in the DL Access Zone or DL Relay Zone in the downlink, and R-RTI (Relay Receive to Transmit Transition Interval) interval) can be included in a UL access zone or a UL relay zone in uplink. R-TTI and R-RTI can be used to control the timing of frames by considering TTG and RTD between the RS and the upper station. R-TTI and R-RTI can be 0, and can have a value corresponding to the maximum value of one character.

In case the operation of the RS is switched from the transmission mode to the reception mode, the last symbol of the DL access region of the RS frame or the first symbol of the DL relay region thereof can be used as the R-TTI. In this case, the symbol time is set based on the BS frame. R-TTI can be calculated using the following equations (in all the following equations, RSTTG means ARSTTG, RSRTG means ARSRTG, and R_RTD means ARSRTG).

[mathematical formula 1]

In Equation 1 above and the following equations, T _s indicates the OFDMA symbol time.

1. Time-shifted UL frame structure.

The UL frame of the RS can be temporarily shifted before the UL frame of the BS and then transmitted. Such a frame structure is called a time-shifted UL frame structure. Assuming that the time in which the UL frame of the RS is advanced based on the UL frame of the BS is T _adv , the time T _adv can be given as, for example, TTG-R_IdleTime. R_IdleTime is an idle time interval between the DL relay zone and the UL access zone in the RS frame. R_IdleTime can have a value equal to or smaller than TTG. That is, the time-shifted UL frame structure can be applied to a case where R_IdleTime has a value smaller than TTG.

In a time-shifted UL frame structure, in case the operation of the RS is switched from receive mode to transmit mode, the last symbol of the UL access zone of the RS frame or the first symbol of the UL relay zone of the RS frame can be used as R -RTI. This R-RTI can be used to match RSRTG and R_RTD between RS and superordinate station. In this case, the symbol time is set based on the BS frame. R-RTI can be calculated using the following equation.

[mathematical formula 2]

In the above equation, R_RTD is the round-trip delay between the RS and the superordinate station (ie, BS). R_IdleTime is equal to or greater than M_RTD/2. Here, M_RTD is the round-trip delay between the MS and the superordinate station (ie, RS). If R_IdleTime is equal to TTG, R-RTI can be equal to the time of one OFDMA symbol.

2. Time aligned UL frame structure.

The UL frame of the RS can be temporarily aligned with the UL frame of the BS and then transmitted. Such a frame structure is called a time-aligned UL frame structure.

In a time-aligned UL frame structure, in case the operation of the RS is switched from receive mode to transmit mode, the last symbol of the UL access zone of the RS frame or the first symbol of the UL relay zone of the RS frame can be used Make R-RTI. This R-RTI can be used to match RSRTG and R_RTD between RS and superordinate station.

FIG. 9 is a diagram showing an example of a TDD frame structure.

Referring to FIG. 9, the ratio of DL subframes to UL subframes is 5:3. The TDD frame structure can be applied to, for example, any one of channel bandwidths 5, 10, and 20 MHz (G=1/8). The number of subframes allocated to the relay zone is 2 in downlink, and the number of subframes allocated to the relay zone is 1 in uplink.

In the RS TDD frame, R-TTI (Relay Transmit to Receive Transition Interval) can be included in the DL access region in the downlink, and R-RTI (Relay Receive to Transmit Transition Interval) can be included in the In the UL relay zone in the uplink.

FIG. 10 is a diagram showing an FDD DL frame structure.

It is assumed that the RS uses an RS frame time-aligned with the BS frame, as shown in FIG. 10 . If ARSTTG is less than or equal to 1/2RTD, the DL frame structure of the RS can be used in the same manner as the DL frame structure of the BS.

If ARSTTG is greater than 1/2RTD, some symbols in the DL subframe of the RS can be used as transition time. The transition time is a time including (ARSTTG-1/2RTD), and may be a time corresponding to the maximum value of one symbol. For example, in case the RS receives a signal from the BS in DL subframe 4 (DL SF4), the RS operates in transmission mode in DL subframe 3, and then operates in reception mode in DL subframe 4. Therefore, ARSTTG between DL subframe 3 and DL subframe 4 is required. In addition, the RS receives a signal transmitted in DL subframe 4 of the BS frame after 1/2RTD. Therefore, if ARSTTG is greater than 1/2RTD, it takes as much time as (ARSTTG-1/2RTD) as transition time. If the conversion time is included in the unit of symbol, a maximum value of one symbol can be used. In other words, a time of ARSTTG is required between DL subframe 3 and DL subframe 4 in the RS frame. Here, if the time of ARSTTG is less than or equal to 1/2RTD, it does not become a problem. However, if the time of ARSTTG is greater than 1/2RTD, some symbols of DL subframe 3 or some symbols of DL subframe 4 are synthetically used as transition time.

If (1/2RTD+IdleTime) is longer than (ARSTTG-1/2RTD), the RS can transmit the DL access zone earlier at (ARSTTG-1/2RTD) without having to do a DL access zone of the RS and a DL access zone of the BS. Enter the zone for time alignment. However, if (1/2RTD+IdleTime) is shorter than or equal to (ARSTTG-1/2RTD), the RS uses some symbols between the DL relay zone and the DL access zone of the next frame as transition time.

Generally speaking, ARSTTG is longer than 1/2RTD. Also, (1/2RTD+IdleTime) is longer than (ARSTTG-1/2RTD) in most frame configurations except the case of 8.75MHz (1/4CP).

The transition time (ie, R-TTI or R-RTI) of the above-mentioned FDD DL frame for the RS can be represented by the following equation.

In case the operation of the RS is switched from the transmission mode to the reception mode, the last symbol of the DL access region of the RS frame or the first symbol of the DL relay region of the RS frame can be used as the R-TTI. This R-TTI can be used to match the ARSTTG and R_RTD between the RS and the upper station. In this case, the symbol time is set based on the BS frame. R-TTI can be calculated using the following equation.

[mathematical formula 3]

In case the operation of the RS is switched from receive mode to transmit mode, (the last symbol of the DL relay zone of the RS frame and IdleTime) or (IdleTime and the first symbol of the DL access zone of the next frame) can be used as R -RTI. In an alternative example, IdleTime can be used as R-RTI. That is, R-RTI can be calculated using the following equation.

[mathematical formula 4]

FIG. 11 is a diagram showing an FDD UL frame structure.

In the case where the RS uses an RS frame that is not time-aligned with the BS frame as shown in Figure 11, if the IdleTime is greater than or equal to (ARSRTG+ARSTTG), the UL access zone of the RS is before the UL access zone of the BS. Zones can be transmitted through ARSRTG.

In the case where the RS uses an RS frame that is not time-aligned with the BS frame as shown in FIG. Some symbols can be used for conversion time. For example, one symbol in a UL subframe can be divided and used in two switching times. One of the transition times can be used between the UL access zone of the RS frame and the UL relay zone for ARSRTG purposes, and the other of the transition times can be used between the UL relay zone and the UL access zone of the RS frame Between for the purpose of ARSTTG.

The transition time (ie, R-TTI or R-RTI) of the above-mentioned FDD UL frame for the RS can be expressed using the following equation.

1. Time-shifted UL frame structure

The UL frame of the RS may be a time-shifted UL frame that has been temporarily shifted between the UL frames of the BS. Assuming that the time by which the UL frame of the RS is advanced based on the UL frame of the BS is T _adv , this time T _adv corresponds to a case where the time is not 0. This time T _adv can be given eg as IdleTime-R_IdleTime.

In the time-shifted UL frame structure, when the operation of the RS is switched from receive mode to transmit mode or from transmit mode to receive mode, (the last symbol of the UL access area of the RS frame + IdleTime) or (the The first symbol of the UL relay zone + IdleTime) can be divided and used in R-RTI and R-TTI. R-TTI or R-RTI is usually calculated using the following equation.

[mathematical formula 5]

2. Time-aligned UL frame structure

The UL frame of the RS can be time aligned with the UL frame of the BS and then transmitted. Such a frame structure is called a time-aligned frame structure. That is, this corresponds to the case where the time T _adv is 0.

In a time-aligned UL frame structure, in case the operation of the RS is switched from receive mode to transmit mode, the last symbol of the UL access zone of the RS frame or the first symbol of the UL relay zone of the RS frame can be used Make R-RTI. Also, in case the operation of the RS is switched from transmission mode to reception mode, if RSTTG is greater than (R_RTD/2+IdleTime), the last symbol of the UL relay zone can be used as R-TTI.

FIG. 12 is a diagram showing an example of including switching time in an FDD frame.

Figure 12 shows where in an FDD DL frame from among RS frames, R-TTI is included in the last symbol of the DL access zone and R-RTI is included in the last symbol of the DL relay zone and/or IdleTime example in . In addition, this figure shows that in an FDD UL frame from among RS frames, R-RTI is included in the first symbol of the UL relay zone and R-TTI is included in the last symbol of the UL relay zone and/or or example in IdleTime

As described above, by considering whether the RS frame is a TDD frame or an FDD frame, transmission mode and reception mode switching time such as RSTTG and RSRTG, propagation delay time, IdleTime and R_IdleTime, in a specific subframe, the RS can include such as R- Transition time for TTI or R-RTI. Therefore, according to the present invention, it is possible to communicate with an RS included in a wireless communication system even without greatly changing a frame structure between an existing BS and an existing macro MS.

FIG. 13 is a diagram showing the structures of RS and BS.

The BS 500 includes a processor 510, a memory 530, and a radio frequency (RF) unit 520. The processor 510 performs scheduling for allocating radio resources to RSs and receiving signals from the RSs. In the above-described embodiments, the procedures, schemes, and functions performed by the BS can be implemented by the processor 510 . The memory 530 is coupled to the processor 510 and configured to store various information for driving the processor 510 . RF unit 520 is coupled to processor 510 and is configured to transmit radio signals and/or receive radio signals. A BS can become a source station or a destination station.

The RS 600 includes a processor 610, a memory 620 and an RF unit 630. In the foregoing embodiments, the processes, schemes and functions performed by the RS can be implemented by the processor 610 . The memory 620 is coupled to the processor 610 and configured to store various information for driving the processor 610 . RF unit 630 is coupled to processor 610 and is configured to transmit radio signals and/or receive radio signals.

Processors 510, 610 can include application specific integrated circuits (ASICs), other chipsets, logic circuits, and/or data processors. The memories 530, 620 can include read only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and/or other storage devices. The RF unit 520, 630 can include baseband circuitry for processing radio signals. When the above-described embodiments are implemented in software, the above-described schemes can be implemented using modules (or processes or functions) for performing the above-described functions. This module can be stored in the memory 530 , 620 and executed by the processor 510 , 620 . The memory 520, 620 can be located inside or outside the processor 510, 610 and coupled to the processor 510, 610 using various well-known means.

The present invention can be realized in hardware or software or using a combination thereof. Capable of using Application Specific Integrated Circuits (ASICs), Digital Signal Processing (DSPs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microprocessors, other electronic units or designed as A combination of them performing the functions described above realizes a hardware embodiment. A software embodiment can be implemented using modules for performing the functions described above. Software can be stored in a memory unit and executed by a processor. It is well known to those skilled in the art that various devices can be used as a memory unit or as a processor.

The RS can perform communication with the BS or the relay MS by considering an operation switching time between a reception mode and a transmission mode and a transmission delay time required for transmitting and receiving signals. Therefore, even without greatly changing the frame structure between the existing BS and the existing macro MS, it is possible to communicate with the RS included in the wireless communication system.

While the invention has been shown and described in conjunction with exemplary embodiments thereof, it will be appreciated by those skilled in the art that other modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. The present invention is changed and modified in various ways.

Claims (8)

1., in the method comprising the transmitting and receiving of RS described in the wireless communication system of relay station RS signal, described method comprises:

The frame configuration information about RS frame is received from base station (BS);

Based on described frame configuration information, configuring downlink (DL) access area and DL relay area in described RS frame, in described down link (DL) access area, signal is launched into the relaying mobile radio station (MS) be connected with described RS, from described BS Received signal strength in described DL relay area;

In described DL access area, described signal is transmitted into described relaying MS; And

In described DL relay area, receive described signal from described BS,

Wherein, be positioned at last OFDM (OFDM) symbol of described DL access area the first change-over time (R-TTI), the duration of wherein said R-TTI is calculated by following equation:

In above-mentioned equation, RSTTG is that described RS is switched to the time needed for accepting state from transmission state, and R_RTD is the propagation delay time between described RS and described BS, T _san OFDM symbol time, and

Wherein, the second change-over time (R-RTI) is the last OFDM symbol being positioned at described DL relay area when described RS is switched to transmission state from accepting state.

2. method according to claim 1, wherein, described RS frame is Frequency Division Duplexing (FDD) (FDD) descending chain circuit frame.

3. in the wireless communication system comprising RS, relay station (RS) transmits and receives a method for signal, and described method comprises:

The frame configuration information about RS frame is received from base station (BS);

Based on described frame configuration information, configure in described RS frame wherein from up link (UL) access area of the relaying MS Received signal strength be connected with described RS and wherein signal be launched into the UL relay area of described BS;

In described UL access area, receive described signal from described relaying MS; And

In described UL relay area, described signal is transmitted into described BS,

Wherein, when described RS is switched to transmission state from accepting state, be positioned at the first OFDM (OFDM) symbol of UL relay area the first change-over time (R-RTI), and

Wherein, when described RS is switched to accepting state from transmission state, be positioned at the last OFDM symbol of described UL relay area the second change-over time (R-TTI).

4. method according to claim 3, wherein, described RS frame is frequency division multiplexing (FDD) uplink frame.

5. a relay station (RS), comprising:

Radio frequency (RF) unit, described radio frequency (RF) unit is configured to transmit and receive radio signal; And

Processor, described processor is connected to described RF unit,

Wherein, described processor is arranged to:

The frame configuration information about RS frame is received from base station (BS);

Based on described frame configuration information, configuring downlink (DL) access area and DL relay area in described RS frame, in described down link (DL) access area, signal is launched into the relaying mobile radio station (MS) be connected with described RS, from described BS Received signal strength in described DL relay area;

In described DL access area, described signal is transmitted into described relaying MS; And

In described DL relay area, receive described signal from described BS,

Wherein, be positioned at last OFDM (OFDM) symbol of described DL access area the first change-over time (R-TTI), the duration of wherein said R-TTI is calculated by following equation:

In above-mentioned equation, RSTTG is that described RS is switched to the time needed for accepting state from transmission state, and R_RTD is the propagation delay time between described RS and described BS, T _san OFDM symbol time, and

Wherein, the second change-over time (R-RTI) is the last OFDM symbol being positioned at described DL relay area when described RS is switched to transmission state from accepting state.

6. RS according to claim 5, wherein said RS frame is Frequency Division Duplexing (FDD) (FDD) descending chain circuit frame.

7. a relay station (RS), comprising:

RF unit, described RF unit is configured to transmit and receive radio signal; And

Processor, described processor is connected to described RF,

Wherein, described processor is arranged to:

The frame configuration information about RS frame is received from base station (BS);

Based on described frame configuration information, configure in described RS frame wherein from up link (UL) access area of the relaying MS Received signal strength be connected with described RS and wherein signal be launched into the UL relay area of described BS;

In described UL access area, receive described signal from described relaying MS; And

In described UL relay area, described signal is transmitted into described BS,

Wherein, when described RS is switched to transmission state from accepting state, be positioned at the first OFDM (OFDM) symbol of UL relay area the first change-over time (R-RTI), and

Wherein, when described RS is switched to accepting state from transmission state, be positioned at the last OFDM symbol of described UL relay area the second change-over time (R-TTI).

8. RS according to claim 7, wherein, described RS frame is Frequency Division Duplexing (FDD) (FDD) uplink frame.