RU2394384C2 - Device and method for supporting relay service in broadband wireless access communication system with multiple relay steps - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: device and method are disclosed for generating a subframe for supporting a relay service in a broadband wireless access (BWA) communication system with multiple relay steps, in which a first subframe zone is created for at least one connection setup between a base station (BS) and a first mobile station (MS) within the coverage zone of the base station and connection setup between at least one relay station (RS) and a second mobile station within the coverage zone of the said at least one relay station, and a second subframe zone is created for at least one connection setup between the given base station and the said at least one relay station and connection setup between the said at least one relay station and another relay station.

EFFECT: free configuration of retransmission links in a BWA communication system with multiple relay steps.

40 cl, 17 dwg

Description

FIELD OF THE INVENTION

The present invention relates to broadband wireless access (BWA) communication systems with multiple relay steps, in particular, to a device and method for synchronously providing forward link service and relay relay service in a broadband wireless access communication system (BWA) with multiple relay steps .

State of the art

One of the most critical requirements for deploying a fourth-generation (4G) mobile communications system is to build a self-configured wireless network. A self-configurable wireless network is a wireless network that is configured in a stand-alone or distributed manner without being controlled by a central system to provide mobile services. For a fourth generation (4G) mobile communication system, cells with very small radii are defined in order to provide high-speed connections and place more calls. The traditional centralized wireless network structure is not self-configurable. However, the wireless network must be built in such a way as to be under distributed control and actively cope with such changes in environmental conditions as the addition of new base stations (BS). That is why a fourth-generation (4G) mobile communication system requires a self-configuring wireless network.

For the actual deployment of a self-configurable wireless network, the methods used for ad-hoc networks (self-organizing peer-to-peer networks with an arbitrary structure) must be implemented in a wireless access communication system. Such a prime example is a Broadband Wireless Access (BWA) communication system with multiple relay steps, configured by applying a multi-relay scheme used for an ad-hoc network to a Broadband Wireless Access Network (BWA) with fixed base stations (BS).

In the general case, since the base station (BS) and the mobile station (MS) communicate with each other via a forward link, a very reliable wireless link can easily be established between the base station and the mobile station in a Broadband Wireless Access (BWA) communication system. However, due to the fixedness of the base stations, the wireless network configuration is not flexible, making it difficult to provide efficient service in a wireless environment experiencing fluctuating traffic distribution and a significant change in the number of calls required.

The aforementioned disadvantage can be overcome by a relay service that delivers data in a few transit steps using a plurality of neighboring mobile stations or neighboring relay stations (RS). The use of a scheme with several relay steps contributes to the quick reconfiguration of the network in response to changing environmental conditions and makes the operation of the entire wireless network efficient. In addition, a wireless channel with a better channel status can be provided to the mobile station by setting up relay stations between the base station and the mobile station, and thus establishing a path with several relay steps through the relay station. Mobile stations may be provided with high-speed data channels in a shadow area or in an area in which communication with the base station is not available, and the cell coverage may be expanded.

FIG. 1 illustrates the configuration of a typical Broadband Wireless Access (BWA) communication system with multiple relay steps.

As shown in FIG. 1, in a Broadband Wireless Access (BWA) communication system with multiple relay steps, mobile stations 140, 150, 160 and 170 (MS1-MS4) can receive Broadband Wireless Access (BWA) services through a BS 100 base station, a main relay station (RS1) 110 and auxiliary relay stations (RS2) 120 and 130.

The mobile stations MS1 and MS2 within the radio coverage area 101 of the base station 100 communicate with the base station 100 via the direct communication lines L1. The mobile station MS2, which is located at the cell boundary of the base station 100 and, thus, is placed in conditions with a poor channel condition, can receive a channel with a higher data rate through the communication line L2 between the relay station and the mobile station (RS-MS), provided by the auxiliary relay station 130, compared with the speed through the forward link L1.

Mobile stations MS3 and MS4 outside the radio coverage area 101 of the base station 100 communicate with the base station 100 via communication lines L3 between the relay station and the mobile station (RS-MS) provided by the main relay station 110. Communication lines between the base station 100 and the mobile stations MS3 and MS4, through the main relay station 110, expand the cell coverage. The mobile station MS4, which is located at the cell boundary of the main relay station 110 and thus placed in a poor channel condition, can increase its throughput using the communication line L4 between the relay station and the mobile station (RS-MS) provided by auxiliary relay station 120.

As described above, when the mobile station is in a poor channel condition at the cell boundary of the base station or in a shadow area exposed to shielding effects, such as buildings, the Broadband Wireless Access (BWA) communication system enables the mobile station to communicate with the base station by providing wireless channel with better quality for the mobile station through the relay station. In other words, the base station can provide a high-speed data channel for the cell boundary and the shadow zone and expand its radio coverage area using a multi-relay scheme.

Relay stations 110, 120, and 130 are divided into a main relay station (relay station 110), which extends the cell coverage, and auxiliary relay stations (relay stations 120 and 130), which increase throughput in accordance with their operational capabilities.

As indicated above, the main relay station 110 serves to expand the radio coverage of the cell of the base station 100. Since the mobile stations MS3 and MS4 have difficulty in receiving services directly from the base station 100, they synchronize with the base station 100 and perform network login to the base station 100 through the main relay station 110. Therefore, the main relay station 110 provides functionality for the initial access of the mobile stations 160 and 170, that is, provides a control channel (or channel traffic) and a random access channel for the mobile stations MS3 and MS4.

Auxiliary relay stations 120 and 130 relay services for mobile stations MS2 and MS4 within their cell coverage area in order to increase service throughput. Mobile station MS2 receives a control channel and a random access channel from base station 100 and a traffic channel from an auxiliary relay station 130. Mobile station MS4 receives a control channel and a random access channel from base auxiliary relay station 110 and a traffic channel from auxiliary relay station 120.

Typically, in a Broadband Wireless Access (BWA) communication system, transmission / reception is performed between the base station and the mobile station in frames having the configuration illustrated in FIG. 2. FIG. 2 illustrates a time division duplex (TDD) frame structure compatible with the Institute of Electronics and Radio Engineering (IEEE) 802.16 standard for transmitting / receiving data between a base station and a mobile station.

As shown in FIG. 2, a TDD frame 200 is divided into a downlink (DL) subframe 210 and an uplink (UL) subframe 220 with a guard region located therebetween, referred to as a transition between transmission and reception (TTG). Between the TDD frames, a guard area is inserted, called the receive-transmit transition gap (RTG).

The preamble and common control channel are included in the mandatory slots of the downlink subframe 210 and are broadcast to the radio coverage area of the cell of the base station. Mobile stations within the radio coverage area of the base station receive synchronization and control information from the preamble and the common control channel.

As described above, the main relay station provides Broadband Wireless Access (BWA) services to mobile stations or relay stations that have difficulty establishing direct lines of communication with the base station, since they are located outside the radio coverage area. Therefore, the main relay station must provide the mobile stations or the relay stations with control information and initial approval slots for entering the network, as well as a user data service. In particular, the main relay station should provide service through an indirect communication line in the same configuration as through a direct communication line, as illustrated in FIG. 3 to guarantee backward compatibility for mobile stations.

For a relay service, after receiving a control channel or a traffic channel from a base station or a mobile station, the relay station relays them. Therefore, the relay station performs both transmission and reception within a unidirectional subframe.

FIG. 3 illustrates a TDD frame structure in a conventional Broadband Wireless Access (BWA) communication system with multiple relay steps.

As shown in FIG. 3, the unidirectional subframe 300 is divided into a forward link zone 301 and an indirect link zone 303, and another unidirectional subframe 310 is divided into a forward link zone 311 and an indirect link zone 313. For the relay service, the predetermined portions of subframes 300 and 310 are allocated to indirect link zones 303 and 313. Thus, the relay station receives information and data for relay in the forward link areas 301 and 311 and relays them in the indirect link areas 303 and 313.

For example, the main relay station receives control information and the traffic packet to be relayed from the base station or mobile station in the forward link area 301 or 311 and then relays them to the base station or mobile station in the indirect link area 303 or 313.

The auxiliary relay station receives the unidirectional traffic packets to be relayed from the mobile station or base station in the forward link area 311 or 301 and then relays them to the mobile station or base station in the indirect link area 303 or 313.

When communication is carried out in the frame structure illustrated in FIG. 3, different nodes providing a Broadband Wireless Access (BWA) service have different frame timing, that is, in a Broadband Wireless Access (BWA) communication system, different nodes operate asynchronously, as illustrated in FIG. four.

Figure 4 is a diagram illustrating the timing of the transmission and reception of mobile stations in a conventional Broadband Wireless Access (BWA) communication system with several relay steps.

As shown in FIG. 4, a mobile station that receives services on a forward link from a base station has the timing of a frame 421 of a base station, since communication is in forward link areas 401 and 411. On the other hand, a mobile station that receives relay link services from the relay station has the timing of the relay station frame 423, since the communication is in indirect link zones 403 and 413.

Typically, in a Broadband Wireless Access (BWA) communication system, synchronization and handoff are performed based on control information and preambles transmitted at a fixed position in a frame. However, since mobile stations operate asynchronously depending on the entity that provides them services, as illustrated in FIG. 4, handoff and synchronization are very difficult, as illustrated in FIG. 5.

FIG. 5 illustrates signal streams when mobile stations move in a traditional Broadband Wireless Access (BWA) communication system with several relay steps.

As shown in FIG. 5, when the mobile station 520 (MS1) moves from the base station 500 to the radio coverage area of the main relay station 510 when receiving services from the base station 500, the mobile station MS1 must receive the preamble and control information from the main relay station 510.

When the mobile station 530 (MS2) moves from the main relay station 510 to the base station 500 while receiving services from the main relay station 510, the mobile station MS2 must receive the preamble and control information from the base station 500.

Disclosure of invention

Technical problem

However, as illustrated in FIG. 3, the base station 500 and the main relay station 510 operate asynchronously, thereby preventing the mobile stations MS1 and MS2 from receiving the preamble and control information after the handoff.

Furthermore, since the base station provides services to the mobile stations and the relay station simultaneously in the forward link subframe, as illustrated in FIG. 3, the freedom to configure a system in which a base station supports a relay station is low.

Technical solution

An aspect of the present invention is to solve at least the above problems and / or to overcome the disadvantages and provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method and apparatus for generating a frame for enabling a mobile station to efficiently perform handoff and receive synchronization in a Broadband Wireless Access (BWA) communication system with several relay steps.

Another aspect of the present invention is to provide a method and apparatus for forming a frame to increase the freedom of configuring relay links in a Broadband Wireless Access (BWA) communication system with several relay steps.

An additional aspect of the present invention is to provide a device and method for synchronizing between forward link service and relay link service by forming a subframe, including a trunk subframe and a relay link subframe, in a multi-band wireless access (BWA) communication system relay steps.

In accordance with an aspect of the present invention, there is provided a method of generating a subframe for supporting a relay service in a Broadband Wireless Access (BWA) communication system with several relay steps, in which a first subframe zone is configured for at least one of a communication between the base station and the first mobile station in within the radio coverage area of this base station and communicating between each relay station and the second mobile station within the radio coverage area of that relay station and the second subframe zone is formed for at least one of communicating between said base station and each relay station and communicating between said relay station and another relay station.

In accordance with another aspect of the present invention, there is provided a method of generating a subframe for supporting a relay service in a Broadband Wireless Access (BWA) communication system with several relay steps, in which a first subframe zone is configured for at least one of a communication between the base station and the mobile station and communicating between the relay station and the mobile station, a second subframe zone is formed for at least one of communicating between the base the communication station between the relay station and the relay station and the relay station for communicating between the relay station and the mobile station, and a third subframe zone is formed for at least one of communicating with the base station and the mobile station and communicating between the relay station and the relay station.

In accordance with a further aspect of the present invention, there is provided a method for providing a base station of a relay service in a broadband wireless access communication system (BWA) with several relay steps, in which the base station communicates with a mobile station in a first subframe area in accordance with a predetermined subframe configuration and implements communication with the relay station in the second zone of the subframe.

In accordance with another aspect of the present invention, there is provided a method for a relay station to provide relay service support in a Broadband Wireless Access (BWA) communication system with several relay steps, in which the relay station performs network input based on control information received from an upstream node and obtains information about the configuration of the subframe to support the relay service, receives a synchronization channel, control information and a traffic packet from this above located node for the second zone of the subframe in the frame with serial number n and sends the synchronization channel and the received control information and the traffic packet of the mobile station for the first zone of the subframe in the frame with serial number (n + 1).

In accordance with another aspect of the present invention, there is provided apparatus for supporting a relay service in a Broadband Wireless Access (BWA) communication system with several relay steps, in which the timing controller generates a transmit and receive timing signal for the signal for the communication area of the mobile station to communicate with the mobile station and for the signal for the communication zone of the relay station for communicating with the relay station in accordance with the configuration of the frame, the radio frequency This antenna switch separates the signal for the communication zone of the mobile station and the signal for the communication zone of the relay station, and the transceiver communicates with either the mobile station or the relay station in accordance with the transmission and reception timing signal.

Beneficial effects

According to the present invention, as described above, a broadband wireless access communication (BWA) communication system with several relay steps multiplexes a trunk area and a time division relay area in a signal transmission period. As a result, direct service and relay service are transparently provided to mobile stations in synchronized frames. Consequently, handoffs and synchronization are facilitated for mobile stations. In addition, since the zone of the relay line in which the relay station receives the service is independent of the area of the trunk, the freedom to configure the relay line can be increased in accordance with the number of relay steps and the channel environment.

List of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings.

FIG. 1 illustrates service provision with a multi-step relay scheme in a typical Broadband Wireless Access (BWA) communication system;

FIG. 2 illustrates a TDD frame structure in a typical Broadband Wireless Access (BWA) communication system;

FIG. 3 illustrates a TDD frame structure in a conventional Broadband Wireless Access (BWA) communication system with multiple relay steps;

FIG. 4 is a diagram illustrating temporal characteristics of the transmission and reception of mobile stations in a conventional Broadband Wireless Access (BWA) communication system with several relay steps;

FIG. 5 illustrates signal streams when mobile stations move in a conventional Broadband Wireless Access (BWA) communication system with multiple relay steps;

6 illustrates a subframe structure in a Broadband Wireless Access (BWA) communication system with multiple relay steps in accordance with the present invention;

FIG. 7 illustrates a frame structure in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention;

FIG. 8 and FIG. 9 illustrates relay link subframe structures in a Broadband Wireless Access (BWA) communication system with multiple relay steps in accordance with the present invention;

FIG. 10 illustrates the timing of a base station, a mobile station, and relay stations in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention;

FIG. 11 illustrates a frame structure in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention;

FIG. 12 illustrates a frame structure in a Broadband Wireless Access (BWA) communication system with three or more relay steps in accordance with the present invention;

FIG. 13 illustrates a frame structure for a base station and a main relay station in a Broadband Wireless Access (BWA) communication system with three or more relay steps in accordance with the present invention;

FIG. 14 illustrates a frame structure for an auxiliary relay station and a mobile station in a Broadband Wireless Access (BWA) communication system with three or more relay steps in accordance with the present invention;

FIG. 15 is a flowchart illustrating an operation of a base station in a broadband wireless access (BWA) communication system with several relay steps in accordance with the present invention;

FIG. 16 is a flowchart illustrating the operation of a relay station in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention; and

FIG. 17 is a block diagram of a base station in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention.

Preferred Embodiment

Below, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would complicate the understanding of the invention with unnecessary details.

The present invention provides a methodology for synchronizing between services provided from a base station and a relay station to mobile stations, and increasing the freedom of configuring areas with relay links in a frame in a Broadband Wireless Access (BWA) communication system with several relay steps.

The following description will be made in the context of a time division duplex (TDD) wireless communication system orthogonal frequency division multiple access (OFDM), although the present invention is also applicable to a communication system using any other multiple access scheme, or to a communication system frequency division duplex (FDD). Here, the term “primary relay station”, or “RS1”, is defined as a high-capacity relay station that provides a control signal for an extended radio coverage area, and the term “auxiliary relay station”, or “RS2”, is defined as a low-capacity relay station which relays mainly traffic packets to increase throughput.

In a Broadband Wireless Access (BWA) communication system, a subframe is divided into a trunk subframe and a relay link subframe to send a forward link service and a relay link service with the same time characteristics, synchronously, as illustrated in FIG. . 6. The forward link is the link through which the base station or relay station communicates with the mobile station, and the relay link is the link through which the base station communicates with the relay station, or the relay station communicates with a downstream relay station . A trunk subframe is configured in accordance with the IEEE 802.16 standard.

FIG. 6 illustrates the structure of a subframe in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention.

As shown in FIG. 6, a subframe 600 is divided into a trunk subframe 610 and a relay link subframe 620. A trunk subframe 610 and a relay link subframe 620 are distinguished by time division.

On the downlink, the trunk subframe 610 and the relay link subframe 620 differ depending on the destination of the signal. Transmission from the mobile station to the base station or transmission from the mobile station to the relay station takes place in the trunk subframe 610, while transmission from the relay station to the base station or transmission from the upstream relay station to the downstream relay station takes place in the subframe 620 relay link 620.

On the uplink, the trunk subframe 610 and the relay link subframe 620 differ depending on the signal source. Transmission from a base station to a mobile station or transmission from a relay station to a mobile station occurs in a trunk subframe 610, while transmission from a downstream relay station to an upstream relay station or transmission from a base station to a relay station occurs in a relay line subframe 620 communication.

In the trunk subframe, the base station and the relay station transparently interact with the mobile station. In other words, the base station and the relay station provide the service in such a way that the mobile station is not aware of the difference between the forward link service and the relay line service, and the mobile station is aware of the interaction with the base station. If the information in the Broadband Wireless Access (BWA) communication system goes through several relay steps, the relay link subframe 620 may be divided into a plurality of areas according to the number of communication lines with several relay steps.

Based on the subframe structure illustrated in FIG. 6, the frame may be formed in the form illustrated in FIG. 7.

FIG. 7 illustrates a frame structure in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention.

As shown in FIG. 7, the frame is divided into a downlink subframe 700 and an uplink subframe 710. In accordance with the structure of the subframe illustrated in FIG. 6, the trunk subframe 701 and the relay subframe 703 are time division multiplexed in the downlink subframe 700, while the trunk subframe 711 and the relay subframe 713 are time division multiplexed in the uplink subframe 710.

In each of subframes 700 and 710, a trunk subframe 701 or 711 precedes a relay link subframe 703 or 713 to transparently notify mobile stations of the preamble based frame start and TTG gap position.

The base station 720 and the main relay station 730 communicate with the mobile stations they serve in the subframes 701 and 711 of the trunk. In particular, the forward link service from the base station 720 and the relay link service from the main relay station 730 are provided in the trunk subframes 701 and 711 via frequency division (FDM), spatial division (SDM) or orthogonal frequency division (OFDM).

For transparent relay, the main relay station 730 provides the control information and traffic packet of the mobile station in the same way as the base station 720 provides forward link service for the mobile station. For the auxiliary relay station, a predetermined packet zone 705 or 707 from the base station 720 or the main relay station 730 is allocated, and it provides a unicast traffic channel for the mobile station in the packet zone 705 or 707.

In the relay link subframes 703 and 713, the base station 720 communicates with the main relay station 730, or the relay station 1730 communicates with its downstream relay station. Relay link subframes 703 and 713 have a fixed length or a variable length in accordance with the cell environment. Improved technology can be applied that can define a new function and use for the relay link subframes 703 and 711, and thus the configuration of the relay link subframes 703 and 711 will not be determined in FIG. 7.

In the case where the Broadband Wireless Access (BWA) communication system is expanded to several relay steps, the relay link subframes 703 and 713 may be time-divided in accordance with the number of communication lines with several relay steps, as illustrated in FIG. 8 and 9.

FIG. 8 and 9 illustrate relay link subframe structures in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention. The relay link subframe may be configured to include control channels and traffic channels of various structures.

As shown in FIG. 8 and 9, each of the relay link subframes 803 and 813 is divided according to the number of relay steps.

In FIG. 8, the zones for the relay links are multiplexed in the subframes 803 and 813 of the relay link in descending order of the relay step number. In particular, the communication line between the relay station of the (n-1) th step and the relay station of the n-th step is preceded by the communication line between the base station and the relay station of the first step in the multiplexed relay link subframes 803 and 813.

In FIG. 9, the zones for the relay links are multiplexed in the subframes 803 and 813 of the relay link in ascending order of the relay step number. In particular, the communication line between the base station and the relay station of the first step precedes the communication line between the relay station of the (n-1) th step and the relay station of the n-th step in the multiplexed relay link subframes 803 and 813. Here, the number of relay steps in the system corresponds to the number of relay stations.

As illustrated in FIG. 7, 8, and 9, the base station provides services for the main relay station or the mobile station, and the main relay station provides services for the mobile station or the auxiliary relay station in a separate trunk subframe and a relay bearer subframe. The base station and the relay stations start frames with the same time characteristics, as illustrated in FIG. 10. Thus, the base station and the relay stations synchronously (with the same timing) provide trunk service to the mobile stations.

FIG. 10 illustrates the timing of a base station, a mobile station, and relay stations in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention. The following description is made in the context of a relay system with 2 relay steps. Therefore, the primary and secondary relay stations provide one-step relay services to different mobile stations.

As shown in FIG. 10, the base station 920 sends control information and a traffic packet to the mobile station that it serves in the trunk subframe 901 of the downlink subframe 900 for a time period D_t1. Base station 920 also sends control information and a traffic packet to the main relay station 940 and the auxiliary relay station 930 in the relay link subframe 903 for a period of time D_t3.

The main relay station 940 sends control information and a traffic packet to the mobile station it serves in the trunk subframe 901 for a period of time D_t1 and receives control information and a traffic packet for relay from the base station 920 in the relay subframe 903 for the period time D_t3. If the Broadband Wireless Access (BWA) communication system is expanded to three or more relay steps and includes a two-step relay system, the main relay station 940 divides the time slots of the relay link subframe 903 and sends control information and the traffic packet of the relay station in the next step relaying in a predetermined time slot of a relay link subframe 903. The size of the time slots multiplexed in the relay link subframe 903 is determined adaptively in accordance with the number of relay steps and the channel state.

The control channel period D_t2 is zero for the auxiliary relay station 930 in the trunk subframe 901, and the auxiliary relay station 930 sends a unicast traffic packet to the mobile station for the remaining period, i.e., D_t1-D_t2. In the relay link subframe 903, the auxiliary relay station 930 receives control information and a traffic packet for relay from the base station 920 during the time period D_t3.

Mobile station 950 receives a control channel and a traffic packet from a base station 920 or a relay station in a trunk subframe 901. In the relay link subframe 903, the mobile station 950 ignores the relay link subframe 903, having determined that the subframe 903 is not allocated to it, and thus is placed in an idle state.

During the period of the uplink subframe 910, the base station 920 receives the initial negotiation information and the traffic packet from the mobile station in the trunk subframe 911 for the time period U_t1 and receives the initial negotiation information and the traffic packets from the main relay station 940 and the auxiliary relay station 930 in a relay link subframe 913 for a period of time U_t3.

The main relay station 940 receives the initial negotiation information and the traffic packet for relay from the mobile station for a period of time U_t1 in the trunk subframe 911. The main relay station 940 also sends the initial negotiation information and traffic packets to the base station 920 during the U_t3 time period in the trunk subframe 913. The main relay station 940 compensates for the delay of the radio channel before transmitting the signal.

In the trunk subframe 911, the control channel period U_t2 is zero for the auxiliary relay station 930, and the auxiliary relay station 930 receives a relay traffic packet from the mobile station for the remaining period U_t1-U_t2. The auxiliary relay station 930 sends unicast traffic packets to the base station 920 during the U_t3 time period in the relay link subframe 913. The auxiliary relay station 930 compensates for the delay of the wireless channel before transmitting the signal.

In a trunk subframe 911, the mobile station 950 sends the initial negotiation information and traffic packets to the base station 920 or the relay station for a period of time U_t1. Mobile station 950 compensates for the delay of the wireless channel before transmitting the signal.

The mobile station 950 ignores the relay link subframe 913, determining that the subframe 913 is not allocated to it.

As described above, the relay stations switch between transmission and reception in unidirectional subframes. Accordingly, protection areas (eg, relay station span TTG and relay station span RTG) are required in downlink subframe 900 and uplink subframe 910. For example, each of the protection areas can be formed by setting a short preamble in the first symbol a relay link subframe so that the relay stations can operate in a switched operating mode during the remaining period of the relay link subframe. A short preamble can be created by reducing the number of repeated sequences that form the frame preamble.

Alternatively, the base station generates a predetermined gap between the trunk subframe 901 and the relay link subframe 903 so that the relay station can operate in a switched operating mode.

FIG. 11 illustrates a frame structure in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with another embodiment of the present invention. This embodiment is characterized in that the configuration of the trunk subframe is identical to the configuration of the relay link subframe.

As shown in FIG. 11, in a two-relay system, the downlink subframe 1000 is divided into a trunk subframe 1001 and a relay subframe 1003, and the uplink subframe 1010 is divided into a trunk subframe 1011 and a relay subframe 1013.

The forward link service from the base station and the relay link service from the relay station are provided by frequency division (FDM), spatial division (SDM) or orthogonal frequency division (OFDM in trunk subframes 1001 and 1011.

The base station communicates with the relay station in relay link subframes 1003 and 1013.

The embodiment described above illustrates a frame structure for supporting relay service in a Broadband Wireless Access (BWA) communication system with two relay steps. If the Broadband Wireless Access (BWA) communication system is expanded to three or more relay steps, the frame structure illustrated in FIG. 8 can be created in the specific form illustrated in FIG. 12. With reference to FIG. 12, multiplexing of two zones of a relay link in a relay link subframe to provide multi-relay service will be described.

12 illustrates a frame structure for a Broadband Wireless Access (BWA) communication system with three or more relay steps in accordance with an embodiment of the present invention. The following description is made with the understanding that the base station, relay stations, and mobile stations interact in spatially multiplexed frames, sharing a common frequency. Here, the main relay station is a relay station with a single relay step, which receives data directly from the base station and relay data, and the auxiliary relay station is a relay station with two relay steps, which receives data from the base station through the main relay station and relay data.

As shown in FIG. 12, a frame 1100 with a sequence number j is divided into a downlink subframe 1110 and an uplink subframe 1120. The downlink subframe 1110 is further divided into a first zone 1111, a second zone 1113 and a third zone 1115. An uplink subframe 1120 is further divided into a first zone 1121, a second zone 1123 and a third zone 1125. The second and third zones 1113 and 1115 correspond to a multiplexed subframe 803 of the relay link illustrated in FIG. 8, and the second and third zones 1123 and 1125 correspond to the multiplexed relay link subframe 813 illustrated in FIG. 8.

The first zones 1111 and 1121 include subframes of a communication line between a base station and a mobile station (RS-MS) for communication between a base station 1130 and a first mobile station 1160 (MS1) and subframes of a communication line between a relay station and a mobile station (RS-MS ) for communication between the main relay station 1140 and the second mobile station 1170 (MS2) and between the auxiliary relay station 1150 and the third mobile station 1180 (MS3). The second zones 1113 and 1123 include subframes of the communication line between the base station and the relay station (BS-RS) and subframes of the communication line between the relay station and the mobile station (RS-MS). If the system operates in four or more relay steps, the second zones 1113 and 1123 include link subframes between the base station and the relay station (BS-RS), link subframes between the relay station and the relay station (RS-RS), and line subframes communication between the relay station and the mobile station (RS-MS). Third zones 1115 and 1125 include subframes of a communication link between a base station and a mobile station (BS-MS) and subframes of a communication link between a relay station and a relay station (RS-RS).

There is a TTG gap between the downlink subframe 1110 and the uplink subframe 1120.

When multi-relay service is supported by frame 1100 with sequence number j, base station 1130 sends downlink data to mobile station MS1, which base station 1130 serves, in first and third zones 1111 and 1115. Base station 1130 also sends downlink data the main relay station 1140 in the second zone 1113.

Base station 1130 receives uplink data from mobile station MS1 in the first zone 1121 and third zone 1125 of the uplink subframe 1120. The base station 1130 also receives uplink data from the main relay station 1140 in the second zone 1123.

The main relay station 1140 sends downlink data to the mobile station MS2 it serves in the first zone 1111 of the downlink subframe 1110. The main relay station 1140 also receives downlink data from the base station 1130 in the second zone 1113. In the third zone 1115, the main relay station 1140 sends downlink data to the auxiliary relay station 1150.

In the uplink subframe 1120, the main relay station 1140 receives the uplink data from the mobile station MS2 in the first zone 1121 and sends the uplink data to the base station 1130 in the second zone 1123. In the third zone 1125, the main relay station 1140 receives the uplink data from the auxiliary relay station 1150.

In downlink subframe 1110, the auxiliary relay station 1150 sends downlink data to the mobile station MS3, which is served by the auxiliary relay station 1150, in the first and second zones 1111 and 1113 and receives downlink data from the main relay station 1140 in the third zone 1115.

In the uplink subframe 1120, the auxiliary relay station 1150 receives the uplink data from the mobile station MS3 in the first and second zones 1121 and 1123 and sends the uplink data to the main relay station 1140 in the third zone 1125. If the system operates in four or more steps relay, auxiliary relay station 1150 can interact with a lower level relay station instead of the mobile station MS3 in the second zones 1113 and 1123. Thus, for a system with emya hop relay auxiliary relay station the relay station 1150 is the last step of retransmission, and thus, an auxiliary relay station 1150 communicates with the mobile station MS3 instead of a relay station of a lower level.

Mobile stations MS1, MS2, and MS3 receive downlink data from the nodes with which they are connected in downlink subframe 1110 and send uplink data to nodes in uplink subframe 1120 of frame 1100 with sequence number j.

For example, the mobile station MS1 receives downlink data from the base station 1130 in the first and third zones 1111 and 1115 of the downlink subframe 1110 and sends uplink data to the base station 1130 in the first and third zones 1121 and 1125 of the uplink subframe 1120.

Mobile station MS2 receives downlink data from a primary relay station 1140 in a first area 1111 of a downlink subframe 1110 and sends uplink data to a primary relay station 1140 in a first area 1121 of an uplink subframe 1120.

The mobile station MS3 receives downlink data from the auxiliary relay station 1150 in the first and second areas 1111 and 1113 of the downlink subframe 1110, and sends uplink data to the auxiliary relay station 1150 in the first and second zones 1121 and 1123 of the uplink subframe 1120.

In the case where the Broadband Wireless Access (BWA) communication system operates in such a manner as illustrated in FIG. 12, and each subframe is created in accordance with IEEE 802.16, the frame structures for the base station and the main relay station are illustrated in FIG. 13, and frame structures for the auxiliary relay station and the mobile station are illustrated in FIG. fourteen.

FIG. 13 illustrates a frame structure for a base station and a main relay station for a Broadband Wireless Access (BWA) communication system with three or more relay steps in accordance with the present invention.

As shown in FIG. 13, a frame with a sequence number j is divided into a downlink subframe 1200 and an uplink subframe 1220. The downlink subframe 1200 is divided into first, second and third zones 1211, 1213 and 1215, and the uplink subframe 1220 is divided into first, second and third zones 1221, 1223 and 1225. A TTG gap is inserted between the downlink subframe 1200 and the subframe 1220 uplink.

The base station 1230 and the main relay station 1240 form downlink subframes that will be sent to mobile stations within their radio coverage areas in the first zone 1211 of the downlink subframe 1210. Each downlink subframe sequentially includes a preamble for synchronization, control information and downlink packets. The preamble and control information are in fixed positions.

In the second zone 1213, the base station 1230 generates a downlink subframe to be sent to the main relay station 1240. The downlink subframe sequentially includes a synchronization channel for synchronizing the main relay station 1240, control information and downlink packets.

Thus, the main relay station 1240 receives the signal from the base station 1230 in the second zone 1213.

In the third zone 1215, the base station 1230 goes into idle mode or forms a downlink subframe to be sent to the mobile station MS1. The downlink subframe includes only downlink packets. Also in the third zone 1215, the main relay station 1240 generates a downlink subframe to be sent to the auxiliary relay station, i.e., the upstream relay station generates a downlink subframe for the downstream relay station. The downlink subframe includes a preamble for synchronizing a lower layer relay station, control information and downlink packets.

In the uplink subframe 1220, the base station 1230 and the main relay station 1240 receive control information (eg, an approval signal) and uplink packets from mobile stations within their radio coverage areas in the first zone 1221.

The main relay station 1240 forms an uplink subframe to be sent to the base station 1230 in the second zone 1223. Thus, the base station 1230 receives a signal from the main relay station 1240.

In the third zone 1225, the base station 1230 is inoperative or is receiving a signal from the mobile station MS1. In addition, the main relay station 1240 receives the signal from the auxiliary relay station. Thus, the upstream relay station receives a signal from the downstream relay station in the third zone 1225.

FIG. 14 illustrates a frame structure for an auxiliary relay station and a mobile station in a Broadband Wireless Access (BWA) communication system with three or more relay steps in accordance with an embodiment of the present invention.

As shown in FIG. 14, a frame with a sequence number j is divided into a downlink subframe 1300 and an uplink subframe 1320. The downlink subframe 1300 is divided into first, second and third zones 1311, 1313 and 1315, and the uplink subframe 1320 is divided into first, second and third zones 1321, 1323 and 1325. A TTG gap is inserted between the downlink subframe 1300 and uplink subframe 1320.

The auxiliary relay station 1350 generates downlink subframes for the mobile station MS3 within its radio coverage area in the first and second zones 1311 and 1313 of the downlink subframe 1310. The downlink subframe created in the first zone 1311 sequentially includes a preamble for synchronizing the mobile station MS3, control information and downlink packets. The downlink subframe created in the second zone 1313 includes only downlink packets for the mobile station MS3.

The auxiliary relay station 1350 receives a signal from the main relay station 1340 in the third zone 1315.

In downlink subframe 1310, mobile stations receive downlink subframes from nodes that serve mobile stations.

In the first and second zones 1321 and 1323 of the uplink subframe 1320, the auxiliary relay station 1350 receives control information (eg, a matching signal) and uplink packets from the mobile station MS3.

In the third zone 1325, the auxiliary relay station 1350 forms an uplink subframe for the main relay station 1340. The uplink subframe sequentially includes control information and uplink packets.

Mobile stations form uplink subframes that will be sent to nodes serving mobile stations in a first area 1321. Each uplink subframe sequentially includes control information and uplink packets.

Mobile stations form uplink subframes in accordance with their service nodes in second zone 1323 and third zone 1325. For example, mobile station MS1 interacting with base station 1330 forms an uplink subframe for base station 1330 in third zone 1325. Mobile station An MS3 cooperating with the auxiliary relay station 1350 forms an uplink subframe for the auxiliary relay station 1350 in the second zone 1323.

If the Broadband Wireless Access (BWA) communication system is a system with three or more relay steps and, thus, the auxiliary relay station 1350 is connected to the downstream relay station, the auxiliary relay station 1350 interacts with the downstream relay station instead of the mobile station MS3 in the second zones 1313 and 1323.

In the embodiment described above, the synchronization channel is located at the beginning of each of the first, second and third zones. As another embodiment, a case may be further considered in which a synchronization channel is located at the end of each of the second and third zones.

A description will now be made of the operations of the base station and the relay station for communicating using the above-described frame structure in a Broadband Wireless Access (BWA) communication system.

FIG. 15 is a flowchart illustrating an operation of a base station in a broadband wireless access (BWA) communication system with several relay steps in accordance with the present invention.

As shown in FIG. 15, the base station, in step 1401, allocates resources for the trunk subframe 701 and the relay link subframe 703 that form the frame. The periods of the trunk subframe 701 and the relay link subframe 703 are fixed or adaptively changed in accordance with the service environment. If there is no relay station within the radio coverage area of the base station, the relay link subframe 703 cannot be used. At step 1403, the base station interacts with mobile stations in a subframe 701 of the trunk.

The base station also interacts with the relay stations in the relay link subframe 703 in step 1405. For example, on the downlink, the base station sends control information and traffic packets to the mobile stations in the trunk subframe 701 and then sends control information and traffic packets to the relay stations in relay link subframe 703.

On the uplink, the base station receives initial negotiation information and traffic packets from mobile stations in a trunk subframe 701, and then receives initial negotiation information and traffic packets from relay stations in a relay subframe 703. Then the base station ends the process.

FIG. 16 is a flowchart illustrating the operation of a relay station in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention.

As shown in FIG. 16, after power-up, the relay station in step 1501 monitors reception of the preamble and control information from the base station. After receiving the preamble and control information, the relay station in step 1503 performs a network input using the preamble and control information. In the same way as a mobile station, the relay station performs network input through the trunk, and not through the relay line. Then, the relay station establishes a relay link based on the relay link information obtained from the initialization. Alternatively, the relay station may initialize via the relay link, rather than through the trunk.

At steps 1505 and 1507, the relay station supports broadband services through the relay link and trunk, established in accordance with the capabilities of the base station and the relay capabilities of the relay station. For example, the relay station receives control information and traffic packets for the relay service from the base station or the upstream relay station in the relay link subframe 703 and then sends control information and traffic packets to the mobile station in the trunk subframe 701 from the next frame. If there is a downstream relay station below the relay station, the relay station can send control information and traffic packets to this downstream relay station in the relay link subframe 703. Then the relay station ends the process.

Although it has been described above how the relay station interacts with the base station, the same description also remains valid for the interaction between the relay station and its upstream relay station.

The base station is configured to have a trunk transceiver for communicating with a mobile station and a relay transceiver for communicating with a relay station. However, the base station may support a relay link and a trunk using a single transceiver.

FIG. 17 is a block diagram of a base station in a Broadband Wireless Access (BWA) communication system with several relay steps in accordance with the present invention.

As shown in FIG. 17, the base station includes a first transceiver 1601 for a relay link, a second transceiver 1603 for a trunk, a timing controller 1605, an antenna switch 1607, and an antenna 1609. The first transceiver 1601 and the second transceiver 1603 have the same configuration, and therefore will only be described first transceiver 1601.

The first transceiver 1601 consists of a transmitter 1611, a receiver 1621, and an RF switch 1631. The transmitter 1611 has a frame generator 1613, a resource converter 1615, a modulator 1617, and a digital-to-analog converter (DAC; DAC) 1619.

A frame generator 1613 generates a relay link subframe for delivering control information and traffic packets of the relay station. A frame generator 1643 of the second transceiver 1641 generates a trunk subframe for delivering control information and traffic packets to the mobile station.

Resource converter 1615 converts the relay link subframe received from the frame generator 1613 into communication line packets allocated to the relay link subframe. A modulator 1617 modulates the transformed subframe in accordance with a predetermined level of the modulation and coding scheme (MCS). Digital to Analog Converter (DAC; DAC) 1619 converts a digital signal into an analog signal, increases the frequency of an analog signal to receive a radio signal and provides a radio signal to a radio frequency switch 1631. The receiver 1621 has an analog-to-digital converter (ADC; ADC) 1623, demodulator 1625, inverse resource converter 1627 and block 1629 extraction frames.

An analog-to-digital converter (ADC; ADC) 1623 lowers the frequency of radio signals received from relay stations through a radio frequency switch 1631 in a relay link subframe to receive baseband signals and converts analog baseband signals to digital signals. Demodulator 1625 demodulates digital signals in accordance with a predetermined level of the modulation and coding scheme (MCS). Inverse resource converter 1627 extracts the actual subframes from communication line packets received from demodulator 1625. Frame extractor 1629 extracts a subframe for receiver 1621 from subframes received from inverse resource converter 1627. For example, frame extractor 1629 extracts relay link subframes from uplink subframes communication lines received from relay stations. Block 1659 extracting frames of the second transceiver 1641 extracts the relay link subframes from the uplink subframes received from the mobile stations.

The radio frequency switch 1631 connects either the transmitter 1611 or the receiver 1621 to the antenna switch 1607 under the control of the timing controller 1605.

The timing controller 1605 controls the timing of the transmission and reception during the service period on the relay link or the service period on the trunk.

The antenna switch 1607 sends the radio signal received through the antenna 1609 to the transceiver 1601 or 1603 depending on the period of service on the relay link or the period of service on the trunk.

Although the invention has been shown and described with reference to some of its preferred embodiments, those skilled in the art will understand that various changes can be made to its form and details without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (40)

1. A method of forming a subframe to support a relay service in a wireless communication system with several relay steps, comprising the steps of:
form a first subframe zone for at least one of a communication between the base station (BS) and the first mobile station (MS) within the radio coverage area of the base station and communication between the at least one relay station (RS) and the second mobile station within radio coverage areas of this at least one relay station; and
forming a second subframe zone for at least one of communicating between said base station and said at least one relay station and communicating between said at least one relay station and another relay station. 2. The method according to claim 1, in which the first zone and the second zone are distinguished in a subframe by at least one of time division and frequency division. 3. The method according to claim 1, in which the first zone of the subframe includes at least one of a subframe of the communication line between the base station and the mobile station (BS-MS) and a subframe of the communication line between the relay station and the mobile station (RS-MS) . 4. The method according to claim 3, in which the subframe of the communication line between the base station and the mobile station (BS-MS) and the subframe of the communication line between the relay station and the mobile station (RS-MS) are distinguished by either frequency division multiple access (FDMA) or spatial division multiple access (SDMA) or orthogonal frequency division multiple access (OFDMA). 5. The method according to claim 3, in which the subframe of the communication line between the base station and the mobile station (BS-MS) and the subframe of the communication line between the relay station and the mobile station (RS-MS) have the same configuration. 6. The method according to claim 3, in which said at least one relay station is either a primary relay station that provides a synchronization channel, or an auxiliary relay station that does not provide a synchronization channel. 7. The method according to claim 6, in which, if the at least one relay station is an auxiliary relay station, the subframe of the communication line between the relay station and the mobile station (RS-MS) is zero in the areas for the synchronization channel and the control channel. 8. The method according to claim 1, in which the second zone of the subframe includes at least one of a subframe of the communication line between the base station and the relay station (BS-RS) and a subframe of the communication line between the relay station and the relay station (RS-RS) . 9. The method of claim 8, wherein the subframe of the communication link between the base station and the relay station (BS-RS) and the subframe of the communication line between the relay station and the relay station (RS-RS) are multiplexed by at least one of a time division and a frequency separation. 10. The method according to claim 1, in which the first zone and the second zone of the subframe have either fixed lengths or variable lengths in accordance with the service environment. 11. The method according to claim 1, in which a protective region is inserted between the first zone and the second zone of the subframe. 12. A method of generating a subframe to support a relay service in a wireless communication system with several relay steps, comprising the steps of:
forming a first subframe zone for at least one of communicating between a base station and a mobile station (BS-MS) and communicating between a relay station and a mobile station (RS-MS);
forming a second subframe zone for at least one of communicating between the base station and the relay station (BS-RS), communicating between the relay station and the relay station (RS-RS), and communicating between the relay station and the mobile station (RS-MS ); and
form a third subframe zone for at least one of a communication between the base station and the mobile station (BS-MS) and communication between the relay station and the relay station (RS-RS). 13. The method of claim 12, wherein the first zone, the second zone, and the third zone are distinguished in the subframe by at least one of time division and frequency division. 14. The method of claim 12, wherein the first subframe zone includes at least one of a link subframe between the base station and the mobile station (BS-MS) and a link subframe between the relay station and the mobile station (RS-MS) . 15. The method of claim 14, wherein the subframe of the communication link between the base station and the mobile station (BS-MS) and the subframe of the communication line between the relay station and the mobile station (RS-MS) are distinguished by either frequency division multiple access (FDMA) or spatial division multiple access (SDMA) or orthogonal frequency division multiple access (OFDMA). 16. The method according to 14, in which the subframe of the communication line between the base station and the mobile station (BS-MS) and the subframe of the communication line between the relay station and the mobile station (RS-MS) have the same configuration. 17. The method according to item 12, in which the second zone of the subframe includes at least one of a subframe of the communication line between the base station and the relay station (BS-RS), a subframe of the communication line between the relay station and the relay station (RS-RS) and a subframe of a communication link between the relay station and the mobile station (RS-MS). 18. The method according to 17, in which the subframe of the communication line between the base station and the relay station (BS-RS), the subframe of the communication line between the relay station and the relay station (RS-RS) and the subframe of the communication line between the relay station and the mobile station ( RS-MSs) are distinguished by at least one of time division and frequency division. 19. The method according to item 12, in which the third zone of the subframe includes at least one of a subframe of the communication line between the base station and the mobile station (BS-MS) and a subframe of the communication line between the relay station and the relay station (RS-RS) . 20. The method according to claim 19, in which the subframe of the communication line between the base station and the mobile station (BS-MS) and the subframe of the communication line between the relay station and the relay station (RS-RS) are distinguished by at least one of a time division and a frequency separation. 21. The method according to item 12, in which the first zone, the second zone and the third zone of the subframe have either fixed lengths or variable lengths in accordance with the service environment. 22. The method according to item 12, in which the synchronization channel is located at the beginning of the first zone of the subframe. 23. The method according to item 12, in which the synchronization channel is located either at the beginning or at the end of each of the first zone and the second zone of the subframe. 24. A method for implementing a base station (BS) of support for a relay service in a wireless communication system with several relay steps, comprising the steps of:
communicating with a mobile station (MS) in a first area of a subframe in accordance with a predetermined configuration of the subframe; and
communicate with a relay station (RS) in the second zone of this subframe. 25. The method according to paragraph 24, in which the first zone and the second zone have either fixed lengths or variable lengths in accordance with the service environment. 26. The method according A.25, further containing a stage in which, if the first zone and the second zone have variable lengths, allocate resources for the first and second zones so that the base station communicates in accordance with the allocation of resources for the first and second zones . 27. The method according to paragraph 24, in which between the first zone and the second zone of the subframe is inserted a protective region. 28. The method according to paragraph 24, in which the first zone and the second zone are distinguished in a subframe through at least one of time division and frequency division. 29. The method according to paragraph 24, in which the synchronization channel is located at the beginning of the first zone of the subframe. 30. The method according to paragraph 24, in which the synchronization channel is located either at the beginning or at the end of the second zone of the subframe. 31. A method for a relay station (RS) to implement a relay service support in a wireless communication system with several relay steps, comprising the steps of:
performing a network input based on control information received from an upstream node, and receiving subframe configuration information to support a relay service;
receiving a synchronization channel, control information and a traffic packet from this upstream node for a second subframe zone in a frame with sequence number n; and
send the synchronization channel and the received control information and the traffic packet to the mobile station (MS) for the first zone of the subframe in the frame with a sequence number (n + 1). 32. The method according to p, in which the relay station is either a primary relay station that provides a synchronization channel, or an auxiliary relay station that does not provide a synchronization channel. 33. The method according to p, in which, if the relay station is a secondary relay station, the relay station fills with zeros areas for the synchronization channel and the control channel. 34. The method of claim 31, wherein the upstream node is either a base station (BS) or an upstream relay station. 35. The method according to p, in which the network input comprises the steps of
receiving control information from an upstream node in a set of zones for an upstream node to communicate with a mobile station in accordance with a predetermined subframe configuration; and
perform a network entrance to the upstream node based on the received control information. 36. The method according to p, in which the network input comprises the steps of
receiving control information from an upstream node in a set of zones for an upstream node to communicate with a relay station in accordance with a predetermined subframe configuration; and
perform a network entrance to the upstream node based on the received control information. 37. A device for supporting a relay service in a wireless communication system with multiple relay steps, containing
a timing controller for providing a transmission and reception timing signal for a signal for a communication area of a mobile station (MS) for communicating with a mobile station and for a signal for a communication zone of a relay station (RS) for communicating with a relay station in accordance with a frame configuration;
a radio frequency (RF) antenna switch for separating a signal for a communication zone of a mobile station and a signal for a communication zone of a relay station; and
a transceiver for communicating with either a mobile station or a relay station in accordance with a transmission and reception timing signal. 38. The device according to clause 37, in which the transceiver contains
a first transceiver for communicating with a mobile station; and
a second transceiver for communicating with the relay station. 39. The device according to 38, in which the first transceiver contains
a transmitter for generating a subframe for the mobile station in accordance with a transmission and reception timing signal;
a receiver for receiving a signal from the mobile station in accordance with a transmission and reception timing signal and for recovering data; and
a switch for connecting either a transmitter or a receiver to a radio frequency antenna switch under the control of a timing controller. 40. The device according to 38, in which the second transceiver contains
a transmitter for generating a subframe for the relay station in accordance with a transmission and reception timing signal;
a receiver for receiving a signal from the relay station in accordance with the transmission and reception timing signal and for recovering data; and
a switch for connecting either a transmitter or a receiver to a radio frequency antenna switch under the control of a timing controller.

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