JP2011077563A - Wireless relay apparatus, wireless transmitter and receiver, wireless relay method, wireless transmission and reception method, relay node, and base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless relay apparatus capable of suppressing wasteful assignment of resources in a base station. <P>SOLUTION: The wireless relay apparatus 10 is disposed in a communication cell of the base station and relays wireless communication performed between the base station and a terminal apparatus. A reception part 11 receives a message communicated through a common channel between the terminal apparatus and the base station by a RACH step of the terminal apparatus. On the bases of the receiving situation of the message determined by a determination part 13, a control part 14 determines whether to relay the wireless communication between the terminal apparatus and the base station. Then, a transmission part 17 transmits the message according to the determination to the terminal apparatus through the common channel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a relay technology for wireless communication performed between a base station and a terminal device, and more particularly to a wireless relay device used in a network having a relay station.

Conventionally, a network system that performs wireless communication between a base station and a terminal device is known. In this conventional system, a procedure called a RACH procedure (also referred to as a RACH procedure) is executed when the terminal device changes from the idle state to the connected state (see, for example, Patent Document 1, Non-Patent Documents 1 and 2). When the terminal device starts the calling procedure, an individual channel for communicating with the base station has not been set yet. The terminal device needs to send a signal to the network by some procedure. At this time, in the case of the LTE system defined in 3GPP, a random access channel (RACH), which is an uplink common physical channel, is used by the terminal device to send a signal to the network. This procedure using RACH is the RACH procedure.
JP 2001-560555 A 3GPP TS36.300 v8.2.0 “E-UTRA and E-UTRAN Overall description stage 2” 3GPP TSG RAN WG1 meeting # 46bis R1-062556, “RACH Design Issues of Large Cell Deployment”

  FIG. 21 is a sequence diagram for explaining a conventional RACH procedure. As shown in FIG. 21, the conventional RACH procedure includes four steps.

  In the first step, the terminal device transmits a random access preamble (also referred to as a RACH preamble) to the base station (S1). The base station receives the random access preamble from the terminal device and measures the transmission timing of the terminal device. In order for the terminal device to transmit data to the base station, it is necessary to establish uplink synchronization.

  In the second step, the base station transmits a random access response (also referred to as a RACH response) to the terminal device (S2). The base station is based on T-CRNI (Temporary Cell Radio Network Identifier), which is a temporary ID used between the terminal device and the base station during the RACH procedure, and the timing measured in the first step. The transmission timing of the terminal device after the third step is instructed by a random access response. Further, in order to perform uplink synchronization, a grant (scheduling grant) indicating an uplink resource used by the terminal apparatus to transmit a message to the base station in the next step is indicated by a random access response.

  In the third step, the terminal device transmits an RRC (Radio Resource Control) connection request to the base station (S3). The RRC connection request includes the ID of the terminal device.

  In the fourth step, the base station transmits an RRC connection response to the terminal device (S4). Thereby, a connection is established between the terminal device and the base station, and an individual channel for the terminal device to communicate with the base station can be acquired.

  2. Description of the Related Art In recent years, cellular mobile communication systems have been actively studied on technologies for realizing high transmission rates using high-frequency radio bands in order to realize the transmission of large volumes of data as information becomes multimedia. ing.

  However, when a high-frequency radio band is used, a high transmission rate can be expected at a short distance, but attenuation due to a transmission distance increases as the distance increases. Therefore, when a mobile communication system using a high-frequency radio band is actually operated, the coverage area of the base station becomes small, so that it is necessary to install more base stations. Since installation of a base station requires a reasonable cost, there is a strong demand for a technique for realizing a communication service using a high-frequency radio band while suppressing an increase in the number of base stations.

In response to such a request, in order to expand the coverage area of each base station, it is conceivable to introduce a relay station (relay node) having a role of relaying communication between the base station and the terminal device into the network system. (For example, see Non-Patent Documents 3 and 4). This relay station is arranged at the cell edge portion of the base station for the purpose of improving the reception efficiency at the cell edge of the base station. The relay station belongs to at least one neighboring base station and has a function of relaying communication between the corresponding base station and the terminal device.
IEEE P802.16j / D1 (August 2007) “Part 16: Interface for Fixed and Mobile Broadband Wireless Access Systems” WIRELESS WORLD RESEARCH FORUM “White Paper on Multi-hop Protocols for Relay based on Deployment Concept”

  FIG. 22 is an explanatory diagram illustrating an example of a relay station. FIG. 22 shows a protocol of a control plane (C-Plane) that is a protocol for control signals of a terminal apparatus (UE), a relay station (RN), and a base station (eNB). The relay station illustrated in FIG. 22 is a layer 2 relay having a function up to layer 2, and is also called a layer 2 repeater, a MAC relay, or a MAC repeater. The layer 2 relay has functions such as error correction and retransmission as well as non-regenerative relay (amplify and forward or non-regenerative relay) in which a signal received from a base station is transmitted to a terminal as it is.

  FIG. 23 is a sequence diagram showing the flow of the RACH procedure when a relay station is simply introduced into the conventional network system. In the example of FIG. 23, the flow of the relay process when the terminal apparatus moves from the base station to the area of the relay station during the RACH procedure is shown.

  In that case, as shown in FIG. 23, first, the terminal apparatus transmits a random access preamble to the base station (S10). However, when the terminal device is at the edge part of the communication cell of the base station, the random access preamble may not reach the base station. Here, if the relay station and the base station use the same access slot, the relay station can also receive the random access preamble transmitted from the terminal device to the base station.

  The relay station that has received the random access preamble for the base station from the terminal device transfers the message to the base station (S11). When the base station receives the random access preamble transmitted from the terminal device to the base station via the relay station, the base station determines that the terminal device has moved to the area of the relay station, and sends the next random access response to the relay station. Via the terminal device (S12, S13). At this time, the T-CRNI and grant assigned to the terminal device by the base station shall be selected from the T-CRNI and grant specified to the relay station in advance for the relay station to assign to the terminal device. .

  When receiving the random access response, the terminal device transmits an RRC connection request via the relay station, and the base station transmits an RRC connection response via the relay station (S14 to S17).

  As described above, when a relay station is introduced into the conventional network system, the coverage area of the base station is expanded, and the reception quality deterioration at the cell edge is compensated. Furthermore, if the relay station and the base station use the same access slot in the RACH procedure, the RACH procedure can be continued even if the terminal device moves from the base station to the area of the relay station during the RACH procedure. become.

  However, in a network system having such a relay station, a random access preamble transmitted from one terminal device may be received redundantly by the base station. That is, there are cases where both messages received directly from the terminal device to the base station and messages relayed by the relay station and received by the base station are received by the base station. In such a case, the base station will allocate resources to both random access preambles. In this case, the terminal device selects one resource according to the reception status of the response from the base station and continues communication with the base station. If it does so, there exists a problem that the resource which was not selected by the terminal device will be wasted.

  The present invention has been made to solve the above-described conventional problems, and provides a wireless relay device capable of reducing wasteful resource allocation caused by introducing a relay station in a network system having the relay station. The purpose is to do.

  A radio relay apparatus of the present invention is a radio relay apparatus that is arranged in a communication cell of a base station and relays radio communication performed between the base station and a terminal apparatus, and in the RACH procedure of the terminal apparatus, Message receiving means for receiving a message communicated between the terminal device and the base station using a common channel, and wireless communication between the terminal device and the base station based on the reception status of the message A relay determination unit that determines whether or not to relay; and a message transmission unit that transmits a message according to the determination to the terminal device using the common channel.

  With this configuration, whether to relay wireless communication is determined based on the reception status of messages communicated using the common channel in the RACH procedure of the terminal device. For example, whether to relay wireless communication is determined based on the reception quality of the terminal device included in the preamble signal transmitted from the terminal device, the presence / absence of reception of a response signal within a predetermined determination period, and the like. When it is determined that the necessity for relaying is low, relaying by the wireless relay device is not performed. As a result, only messages transmitted directly from the terminal device to the base station are received by the base station, and useless resource allocation at the base station is suppressed.

  In the radio relay apparatus of the present invention, the message receiving means can receive a preamble signal transmitted from the terminal apparatus to the base station in the RACH procedure, and the preamble signal is received by the terminal apparatus. Reception quality information indicating high or low quality is included, and the relay determination means determines whether or not to relay wireless communication according to the reception quality level based on the reception quality information included in the preamble signal. It has a configuration to determine.

  With this configuration, whether to relay wireless communication is determined based on the reception quality of the terminal device included in the preamble signal from the terminal device. When the reception quality of the terminal device included in the preamble signal is high, it is determined that the necessity for relaying is high, and relaying to the base station is performed by the wireless relay device. Thereby, the reception efficiency in the edge area | region of a communication cell improves. As a result, only messages transmitted directly from the terminal device to the base station are received by the base station, and useless resource allocation at the base station is suppressed.

  The radio relay apparatus of the present invention has a configuration including response signal generation means for generating a response signal for the preamble signal received by the message reception means when it is determined that the reception quality is high. is doing.

  With this configuration, when the reception quality of the terminal device included in the preamble signal is high, there is a high possibility that the terminal device is located near the edge region of the communication cell. That is, the terminal device is located in a region away from the base station, and it is highly likely that it is difficult for the terminal device to communicate directly with the base station. In such a case, a response signal is generated in the wireless relay device, and the response signal is transmitted to the terminal device. In this way, the reception efficiency in the edge area of the communication cell is improved.

  The radio relay apparatus of the present invention further includes a relay transmission unit that relays and transmits the preamble signal received by the message reception unit to the base station when it is determined that the reception quality is high. It has a configuration.

  With this configuration, when the reception quality of the terminal device included in the preamble signal is high, there is a high possibility that the terminal device is located near the edge region of the communication cell. That is, the terminal device is located in a region away from the base station, and it is highly likely that it is difficult for the terminal device to communicate directly with the base station. In such a case, it is determined that the necessity for relay is high, and the preamble signal is relayed to the base station. In this way, relaying by the wireless relay device is performed, and reception efficiency in the edge region of the communication cell is improved.

  In the radio relay apparatus of the present invention, the message receiving means transmits a preamble signal transmitted from the terminal apparatus to the base station in the RACH procedure, and transmits from the base station to the terminal apparatus as a response to the preamble signal. The relay determination means determines a criterion for necessity of relaying the wireless communication when it is determined that the reception quality is low after receiving the preamble signal. It is determined whether or not the response signal has been received within a determination period until the indicated reference time elapses, and whether or not to relay is determined depending on whether or not the response signal is received .

  With this configuration, whether to relay wireless communication is determined based on whether or not a response signal is received within a predetermined determination period. If the response signal is not received within a predetermined determination period after receiving the preamble signal, it is determined that the necessity for relaying is high, and relaying by the wireless relay device is performed. Thereby, the reception efficiency in the edge area | region of a communication cell improves. On the other hand, when a response signal is received within a predetermined determination period, it is determined that the necessity for relaying is low, and relaying by the wireless relay device is not performed. As a result, only messages transmitted directly from the terminal device to the base station are received by the base station, and useless resource allocation at the base station is suppressed.

  The radio relay apparatus of the present invention further includes relay transmission means for relaying and transmitting the preamble signal received from the terminal apparatus to the base station when it is determined that the response signal is not received within the determination period. It has a configuration.

  With this configuration, if a response signal is not received within a predetermined determination period, it is highly likely that it is difficult for the terminal device to communicate directly with the base station. In such a case, it is determined that the necessity for relay is high, and the preamble signal is relayed to the base station. In this way, relaying by the wireless relay device is performed, and reception efficiency in the communication cell is improved.

  In addition, the radio relay apparatus of the present invention generates a response signal for the preamble signal based on a response generation instruction signal received from the base station as a response to the preamble signal relayed from the relay transmission unit. It has a configuration provided with generating means.

  With this configuration, when a response signal is not received within a predetermined determination period and it is determined that the necessity for relay is high, a response signal is generated based on the response generation instruction signal received from the base station, and the response A signal is transmitted to the terminal device. In this way, relaying by the wireless relay device is performed, and reception efficiency in the communication cell is improved.

  A plurality of radio relay apparatuses of the present invention are arranged in a communication cell of a base station, and relay radio communications performed between the base station and a terminal apparatus, wherein the radio relay apparatus In the RACH procedure of the terminal device, message receiving means for receiving a message communicated between the terminal device and the base station using a common channel, and a signature used in the communication of the message are stored in the wireless relay device Signature determining means for determining whether or not the assigned signature is assigned, and relay transmitting means for relaying and transmitting the message received from the terminal device to the base station when the assigned signature is determined. The wireless relay device is assigned at least one signature, and the wireless relay devices adjacent to each other are assigned the least One signature has an arrangement that is assigned so as not to overlap also.

  With this configuration, when one terminal apparatus performs the RACH procedure in the overlapping part of communication cells of a plurality of radio relay apparatuses, a plurality of messages relayed by the respective radio relay apparatuses are received by the base station. Is suppressed. In this case, the terminal device selects one wireless relay device and transmits a message using the assigned signature of the selected wireless relay device. Each wireless relay device relays and transmits only a message using the assigned signature of the wireless relay device to the base station. Thereby, only one radio relay apparatus selected as the terminal apparatus performs relay transmission of the message. Therefore, a message from one terminal device can be prevented from being relayed by a plurality of wireless relay devices, and useless resource allocation at the base station is suppressed.

  A radio transmission / reception apparatus according to the present invention is a radio transmission / reception apparatus capable of radio communication with a plurality of terminal apparatuses via a plurality of radio relay apparatuses, and is transmitted from the terminal apparatus using a common channel in the RACH procedure of the terminal apparatus. The message reception means for receiving the message, the determination means for determining the wireless relay apparatus that relayed the message based on the resources allocated to each of the wireless relay apparatuses, and the messages from the plurality of terminal apparatuses are different from each other. Response generator for generating a plurality of response signals different for each of the wireless relay devices as a response to the plurality of messages when it is determined that the relay is performed by the wireless relay device, and a plurality of responses different for each of the wireless relay devices Response transmitting means for transmitting a signal using the common channel Has a configuration equipped with.

  When a plurality of terminal apparatuses simultaneously transmit messages using the same time slot and the same signature when performing the RACH procedure, the plurality of messages relayed by the wireless relay apparatus may be received simultaneously by the wireless transmission / reception apparatus. is there. In this case, the radio relay apparatus uses resources allocated to each when relaying messages. As a result, the wireless transmission / reception device determines the wireless relay device that relayed the message based on the resource, and transmits a different response for each wireless relay device. Therefore, when a plurality of terminal apparatuses simultaneously perform a RACH procedure on a common channel using the same time slot and the same signature, it is possible to reduce the probability of collision between the plurality of terminal apparatuses.

  The radio relay method of the present invention is a radio relay method for relaying radio communication performed between the base station and a terminal device in a radio relay device arranged in a communication cell of the base station, wherein the terminal device In the RACH procedure, a message communicated using a common channel is received between the terminal apparatus and the base station, and wireless communication between the terminal apparatus and the base station is performed based on the reception status of the message. Whether or not to relay is determined, and a message corresponding to the determination is transmitted to the terminal device using the common channel.

  With this method, whether to perform relaying is determined based on the reception status of messages communicated using the common channel in the RACH procedure of the terminal device. As a result, only messages transmitted directly from the terminal device to the base station are received by the base station, and useless resource allocation at the base station is suppressed.

  A radio relay method of the present invention is a radio relay method for relaying radio communication performed between the base station and a terminal device in each of a plurality of radio relay devices arranged in a communication cell of a base station. The radio relay apparatus is assigned at least one signature, and the radio relay apparatuses adjacent to each other are assigned such that the at least one signature does not overlap, and the radio relay method is a RACH procedure of the terminal apparatus. Receiving a message communicated between the terminal device and the base station using a common channel, and whether the signature used in the communication of the message is an assigned signature assigned to the wireless relay device The message received from the terminal device when the assignment signature is determined, To relay transmission to ground stations.

  By this method, when one terminal device performs the RACH procedure in the overlapping part of communication cells of a plurality of wireless relay devices, the terminal device selects one wireless relay device and assigns the assigned signature of the selected wireless relay device. Use to send a message. Then, each wireless relay device relays and transmits only a message using the assigned signature of the wireless relay device to the base station. Therefore, a message from one terminal device can be prevented from being relayed by a plurality of wireless relay devices, and useless resource allocation at the base station is suppressed.

  The wireless transmission / reception method of the present invention is a message transmitted from a terminal device using a common channel in a RACH procedure of the terminal device in a wireless transmission / reception device capable of wireless communication with a plurality of terminal devices via a plurality of wireless relay devices. The wireless relay device that relayed the message is determined based on the resources allocated to each wireless relay device, and it is determined that the messages from the plurality of terminal devices are relayed by different wireless relay devices. If so, a plurality of response signals different for each wireless relay device are generated as responses to the plurality of messages, and a plurality of response signals different for each wireless relay device are transmitted using the common channel.

  By this method, when a plurality of terminal devices transmit messages using the same time slot and the same signature at the same time when performing the RACH procedure, the wireless relay device is assigned to each when relaying the message. Resources are used. Then, the wireless transmission / reception device determines the wireless relay device that relayed the message based on the resource, and transmits a different response for each wireless relay device. Therefore, when a plurality of terminal apparatuses simultaneously perform a RACH procedure on a common channel using the same time slot and the same signature, it is possible to reduce the probability of collision between the plurality of terminal apparatuses.

  The relay node of the present invention has a configuration including the above-described wireless relay device.

  Moreover, the base station of this invention has the structure provided with said radio | wireless transmitter / receiver.

  The present invention has the effect of suppressing the allocation of useless resources at the base station by deciding whether or not to relay wireless communication based on the reception status of messages communicated by the RACH procedure of the terminal device. It is possible to provide a wireless transmission / reception apparatus having the same.

  Hereinafter, a network system according to an embodiment of the present invention will be described with reference to the drawings. The network system of the present embodiment includes a terminal device (such as a mobile phone or a PDA device), a relay station (relay node), and a base station. The relay station is equipped with a wireless relay device, and the base station is equipped with a wireless transmission / reception device.

(First embodiment)
A network system according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating configurations of a radio relay apparatus and a terminal apparatus according to the present embodiment. FIG. 2 is an explanatory diagram illustrating an example of a positional relationship among a base station, a relay station, and a terminal apparatus according to the present embodiment. It is.

  Here, first, the area configuration of the base station and relay station of the present embodiment will be described with reference to FIG. As shown in FIG. 2, the relay station is located in an edge region of a communication cell (also referred to as an area) of the base station. In this example, the terminal device (UE) is located at a boundary point between the areas of the base station (eNB) and the relay station (RN). Further, the area of the base station is larger than the area of the relay station.

  In this case, in the RACH procedure, communication from the terminal device to the relay station and communication from the terminal device to the base station are performed using the same access slot. Therefore, the relay station can also receive the random access preamble (also referred to as RACH preamble) transmitted from the terminal device to the base station. Therefore, although the terminal device communicates with the base station, as shown in FIG. 2, since the terminal device is within the area of the relay station, the relay station also receives a signal transmitted from the terminal device to the base station. can do. In this way, the relay station and the base station use the same access slot in the RACH procedure, so that even when the terminal apparatus moves from the base station to the relay station area during the RACH procedure, the RACH procedure can be continued. Is possible.

  FIG. 3 is an explanatory diagram of the reception quality of signals from the base station or relay station received by the terminal device in such a communication cell of the base station. As shown in FIG. 3, the strength of the received signal from the base station (also referred to as eNB) decreases as the terminal device moves away from the base station. Further, the strength of the received signal from the relay station (also referred to as RN) increases as the terminal device approaches the relay station.

  In FIG. 3, when focusing on the edge region of the communication cell of the base station, if the terminal device is located near the relay station (for example, the cell edge of the base station, the center of the area of the relay station), the terminal device The reception quality (also referred to as Channel Quality Indicator, CQI) of the signal received from the relay apparatus becomes high. In addition, when the terminal device is located at a location away from the relay station (for example, a boundary point between the area of the base station and the relay station), the reception quality of the signal received by the terminal device from the relay device is low. become.

  Next, returning to FIG. 1, the configuration of the wireless relay device 10 will be described. As illustrated in FIG. 1, the wireless relay device 10 includes a reception unit 11, a random access preamble storage unit 12 (also simply referred to as a preamble storage unit), a determination unit 13, and a control unit 14. In addition, the wireless relay device 10 includes a resource storage unit 15, a random access response generation unit 16 (also simply referred to as a response generation unit), and a transmission unit 17.

  The receiving unit 11 receives a message communicated between the terminal device and the base station from the antenna 18 in the RACH procedure. Specifically, the receiving unit 11 receives a random access preamble, a random access response (also referred to as a RACH response), an RRC connection request, an RRC connection establishment, and the like from the terminal device and the base station. Here, the receiving unit 11 corresponds to the message receiving means of the present invention.

  The preamble storage unit 12 includes a memory or the like, stores the random access preamble input from the reception unit 11, and outputs the random access preamble to the determination unit 13 and the transmission unit 17.

  The determination unit 13 determines the reception status of the received message and determines to relay wireless communication. Specifically, the determination unit 13 determines the signature of the random access preamble input from the preamble storage unit 12, and sends a determination result on whether the CQI of the terminal device indicated by the random access preamble is high or low to the control unit 14. Output.

  The control unit 14 determines to relay wireless communication based on the reception status of the received message. For example, when the control unit 14 receives the determination result input from the determination unit 13 and determines that the CQI of the terminal device indicated by the random access preamble is high, the control unit 14 instructs the response generation unit 16 and the transmission unit 17. send. In addition, when it is determined that the CQI of the terminal device indicated by the random access preamble is low, the control unit 14 waits for reception of a random access response from the base station to the terminal device for a certain period of time, and from the base station to the terminal device. When the random access response is not received, an instruction to relay the random access preamble to the base station is sent to the transmission unit 17. Here, the control unit 14 corresponds to the relay determining means of the present invention.

  The resource storage unit 15 stores resources (T-CRNI, grant) to be allocated to terminal devices that have attempted random access. This resource is allocated in advance from the base station.

  When receiving an instruction from the control unit 14, the response generation unit 16 generates a random access response message using the resource input from the resource storage unit 15. For example, when it is determined that the CQI of the terminal device indicated by the random access preamble is high, a random access response message is generated. Here, the response generator 16 corresponds to a response signal generator of the present invention. The generated random access response message is output to the transmission unit 17.

  The transmission unit 17 transmits the random access response message input from the response generation unit 16 or the random access preamble input from the preamble storage unit 12 from the antenna 18 in accordance with an instruction from the control unit 14. In this case, the transmission unit 17 transmits a message according to the necessity of relay. Therefore, the transmission unit 17 corresponds to the message transmission unit 17 of the present invention. In addition, when the random access response is not received within a certain period after receiving the random access preamble, the transmission unit 17 relays and transmits the received random access preamble to the base station. Therefore, it can be said that this transmission unit 17 corresponds to the relay transmission means of the present invention.

  Next, the configuration of the terminal device will be described with reference to FIG. As illustrated in FIG. 1, the terminal device 100 includes a reception unit 101, a signature storage unit 102, a CQI determination unit 103, a random access preamble generation unit 104, and a transmission unit 105.

  The receiving unit 101 receives signals from the base station and the relay device from the antenna 106. The CQI determination unit 102 determines the CQI of the signal received by the reception unit 101 and outputs the determination result to the signature storage unit 102. At this time, the CQI determination is mainly performed based on the reception level of the downlink reference signal.

  The signature storage unit 102 stores the signature group received by the reception unit 101 and used for the random access preamble, selects one signature according to the determination result input from the CQI determination unit 103, and selects the random access preamble generation unit 104. Output to.

  The random access preamble generation unit 104 generates a random access preamble message using the signature input from the signature storage unit 102 and outputs the random access preamble message to the transmission unit 105. Transmitting section 105 transmits the random access preamble message input from random access preamble generating section 104 from antenna 106.

  The operation of the relay station including the wireless relay device 10 configured as described above will be described with reference to FIGS. Here, a case where two terminal devices (terminal devices A and B) are relayed by two relay stations (relay stations A and B) is illustrated.

  FIG. 4 is a sequence diagram showing the flow of the RACH procedure when the reception quality (CQI) of the terminal device indicated by the random access preamble is high. As shown in FIG. 4, first, the two terminal apparatuses both transmit a random access preamble (message 1) to the base station (S100, S101). In this case, it is assumed that the same signature is used in the random access preambles of the two terminal devices. Also, it is assumed that the random access preambles transmitted by the two terminal devices do not reach the base station and are received by the two relay stations, respectively.

  When the reception quality (CQI) of the terminal device indicated by the received random access preamble is high, the relay station that has received the random access preamble transmitted by the terminal device determines to transmit a random access response, and T- A random access response (message 2) to which CRNI and uplink resources (grant) are allocated is transmitted (S102, S103).

  Thereafter, the terminal device transmits an RRC connection request (message 3) to the base station via the relay station (S104 to S107). In response to the RRC connection request from the terminal device, the base station transmits RRC connection establishment (message 4) via each relay station (S108 to S111).

  FIG. 5 is a sequence diagram showing the flow of the RACH procedure when the reception quality (CQI) of the terminal device indicated by the random access preamble is low. As shown in FIG. 5, first, both the two terminal devices transmit a random access preamble (message 1) to the base station (S120, S121). In this case, it is assumed that the same signature is used in the random access preambles of the two terminal devices. The random access preamble transmitted from the terminal device A reaches the base station (S120), but the random access preamble transmitted from the terminal device B does not reach the base station and is received by the relay station B (S121). ). Note that the random access preamble transmitted by the terminal device A is also received by the relay station A.

  First, the case of the terminal device A will be described. When the relay station A that has received the random access preamble transmitted by the terminal device A has a low reception quality (CQI) of the terminal device A indicated by the received random access preamble, a certain time ( In FIG. 5, it is shown by hatching) and waits for a random access response from the base station to the terminal device A to be transmitted.

  When a random access response from the base station to the terminal device A is received within a certain time (S122), the relay station A does not perform relaying. Thereafter, the terminal device A transmits an RRC connection request to the base station (S123), and the base station receives the RRC connection request from the terminal device A and transmits RRC connection establishment to the terminal device (S124).

  Next, the case of the terminal device B will be described. Similarly, the relay station B that has received the random access preamble transmitted by the terminal device B is also constant when the reception quality (CQI) of the terminal device indicated by the received random access preamble is low. It waits for a time (shown by hatching in FIG. 5) and whether or not a random access response is transmitted from the base station to the terminal device B.

  If the random access response from the base station to the terminal device B is not received within a certain time, the relay station B relays the received random access preamble to the base station (S125). Thereafter, the relay station B relays the random access response received from the base station to the terminal device B (S126, S127). The terminal apparatus B transmits an RRC connection request to the base station via the relay station B (S128, S129). The base station responds to the RRC connection request from the terminal apparatus B via the relay station B via the RRC. Connection establishment is transmitted (S130, S131).

  FIG. 6 is a flowchart showing an operation flow when the relay station including the wireless relay device 10 receives the random access preamble. As shown in FIG. 6, when the relay station receives the random access preamble transmitted from the terminal device (S140), the relay station determines the CQI of the terminal device indicated in the random access preamble (S141). If the CQI is high, a random access response message is generated for the received random access preamble (S142), and then the random access response is transmitted to the terminal device (S143).

  When the CQI is low, it waits for a certain time (S144), and determines whether or not a random access response from the base station is received within the certain time (S145). When a random access response is received from the base station within a certain time, relaying is not performed. On the other hand, when a random access response is received from the terminal device at a certain time, the random access preamble is relayed to the base station (S146).

  According to the wireless relay device 10 of the first embodiment as described above, based on the reception status of the terminal device included in the message communicated by the RACH procedure of the terminal device, the wireless communication according to the necessity of relay is performed. By determining the support state, it is possible to suppress useless resource allocation at the base station.

  In the present embodiment, based on the reception quality (CQI) of the random access preamble transmitted from the terminal device, the wireless communication support state is determined according to the necessity of relaying. In this case, the radio relay device 10 is arranged in the edge region of the communication cell of the base station. Therefore, when the reception quality of the terminal device included in the preamble signal is high, it is determined that the necessity for relaying is high, and relaying by the wireless relay device 10 is performed. Thereby, the reception efficiency in the edge area | region of a communication cell improves. As a result, only messages transmitted directly from the terminal device to the base station are received by the base station, and useless resource allocation at the base station is suppressed.

  Specifically, when the reception quality (CQI) of the random access preamble is high, there is a high possibility that the terminal device is located near the edge region of the communication cell. That is, the terminal device is located in a region away from the base station, and it is highly likely that it is difficult for the terminal device to communicate directly with the base station. In such a case, it is determined that the necessity for relay is high, a random access response is generated in the wireless relay device 10, and the random access response is transmitted to the terminal device. In this way, relaying by the radio relay device 10 is performed, and reception efficiency in the edge region of the communication cell is improved. Moreover, according to this, the resource allocation of the terminal device can be distributed and managed on the wireless relay device side (relay station side). That is, distributed management on the wireless relay device side becomes possible.

  Further, in the present embodiment, the wireless communication support state is determined according to the necessity of relay based on whether or not a random access response is received from the base station within a predetermined determination period. If the random access response from the base station is not received within a predetermined determination period after receiving the random access preamble, it is determined that the necessity for relaying is high, and relaying by the wireless relay device 10 is performed. Thereby, the reception efficiency in the edge area | region of a communication cell improves. On the other hand, when a random access response is received from the base station within a predetermined determination period, it is determined that the necessity for relaying is low, and relaying by the wireless relay device 10 is not performed. As a result, only messages transmitted directly from the terminal device to the base station are received by the base station, and useless resource allocation at the base station is suppressed.

  Specifically, if a random access response is not received within a predetermined determination period, there is a high possibility that it is difficult for the terminal device to communicate directly with the base station. In such a case, it is determined that the necessity for relay is high, and the random access preamble is relayed to the base station. In this way, relaying by the wireless relay device 10 is performed, and reception efficiency in the communication cell is improved. Moreover, according to this, the relay of a terminal device can be distributed and managed by the base station side and the radio relay apparatus side (relay station side).

  According to the radio relay apparatus 10 of the first embodiment as described above, the relay station determines whether to relay the random access preamble to the base station based on the CQI of the terminal apparatus. Therefore, when the CQI of the terminal device is high, the relay station can directly transmit a random access response to the terminal device, thereby reducing unnecessary signaling.

  When the CQI of the terminal device is low, the relay station waits for a random access response from the base station for a certain time. Thereby, the relay station relays the random access preamble to the base station only when the random access preamble does not reach the base station directly. Therefore, useless resource consumption due to the base station allocating resources to a plurality of random access preambles can be reduced.

(Modification 1)
Next, Modification 1 of the wireless relay device according to the first embodiment will be described with reference to FIGS. 7 and 8. Here, the points different from the first embodiment will be mainly described. Therefore, unless otherwise specified here, the configuration and operation of Modification 1 are the same as those of the first embodiment.

  First, the configuration of the wireless relay device 10 of Modification 1 will be described. The configuration of the wireless relay device 10 of Modification 1 is almost the same as that of the first embodiment shown in FIG. The wireless relay device 10 is configured so that the transmission unit 17 can relay and transmit the random access preamble to the base station when it is determined that the reception quality (CQI) of the random access preamble is high. Therefore, the transmission unit 17 corresponds to the relay transmission unit of the present invention.

  Next, the operation of the relay station provided with the wireless relay device 10 of the first modification will be described. Also here, a case where two terminal apparatuses (terminal apparatuses A and B) are relayed by two relay stations (relay stations A and B) is illustrated.

  FIG. 7 is a sequence diagram showing the flow of the RACH procedure when the reception quality (CQI) of the terminal device indicated by the random access preamble is high. As shown in FIG. 7, first, the two terminal devices both transmit a random access preamble (message 1) to the base station (S100, S101). In this case, it is assumed that the same signature is used in the random access preambles of the two terminal devices. In addition, it is assumed that the random access preambles transmitted by the two terminal devices do not reach the base station and are received by the two relay stations, respectively.

  When the reception quality (CQI) of the terminal device indicated by the received random access preamble is high, the relay station that has received the random access preamble transmitted by the terminal device immediately sends the received random access response (message 2) to the terminal device. Relay (S150, S151). Thereafter, the relay station relays the random access response received from the base station to the terminal device (S152 to S155).

  Thereafter, the terminal device transmits an RRC connection request (message 3) to the base station via the relay station (S104 to S107). In response to the RRC connection request from the terminal device, the base station transmits RRC connection establishment (message 4) via each relay station (S108 to S111).

  FIG. 8 is a flowchart showing an operation flow when the relay station including the wireless relay device 10 receives the random access preamble. As illustrated in FIG. 8, when the relay station receives the random access preamble transmitted by the terminal device (S140), the relay station determines the CQI of the terminal device indicated in the random access preamble (S141). If the CQI is high, the received random access preamble is relayed to the base station (S160).

  When the CQI is low, it waits for a certain time (S144), and determines whether or not a random access response from the base station is received within the certain time (S145). When a random access response is received from the base station within a certain time, relaying is not performed. On the other hand, when a random access response is received from the terminal device at a certain time, the random access preamble is relayed to the base station (S146).

  In the wireless relay device 10 according to the first modification, when the reception quality (CQI) of the random access preamble is high, there is a high possibility that the terminal device is located near the edge region of the communication cell. That is, the terminal device is located in a region away from the base station, and it is highly likely that it is difficult for the terminal device to communicate directly with the base station. In such a case, it is determined that the necessity for relay is high, and the random access preamble is relayed to the base station. In this way, relaying by the radio relay device 10 is performed, and reception efficiency in the edge region of the communication cell is improved. Moreover, according to this modification 1, the relay of a terminal device can be centrally managed by the base station side.

  According to the first modification example, when the base station manages all resources allocated to the terminal device, when the CQI of the terminal device is high, without waiting for a random access response from the base station unnecessarily, The random access preamble can be relayed to the base station.

  In addition, when the CQI of the terminal device is low, the relay station waits for a random access response from the base station for a certain period of time, so that the relay station uses the random access preamble only when the random access preamble does not reach the base station directly. Since relaying to a station, wasteful resource consumption due to the base station allocating resources to a plurality of random access preambles can be reduced.

(Modification 2)
Next, a second modification of the wireless relay device according to the first embodiment will be described with reference to FIGS. Here, the points different from the first embodiment will be mainly described. Therefore, unless otherwise specified here, the configuration and operation of Modification 2 are the same as those of the first embodiment.

  First, the configuration of the wireless relay device 10 of Modification 2 will be described. The wireless relay device 10 of Modification 2 is different from the first embodiment in that an allocation instruction acquisition unit is provided.

  The receiving unit 11 of the second modification receives from the antenna 18 a random access preamble, a random access response, an RRC connection request, an RRC connection establishment, and the like from the terminal device and the base station. The receiving unit 11 receives a resource allocation instruction for the terminal device from the base station, and outputs the received resource allocation instruction to the allocation instruction acquiring unit.

  The allocation instruction acquisition unit generates a random access response in which T-CRNI and grant are allocated to the terminal device instructed to the base station according to the allocation instruction input from the receiving unit 11, and to the specified terminal device The control unit 14 is instructed to transmit. This resource allocation instruction corresponds to the response generation instruction signal of the present invention.

  The control unit 14 receives the determination result input from the determination unit 13 and determines that the reception quality (CQI) of the terminal device indicated by the random access preamble is high, the random access response generation unit 16 (simply a response) An instruction is also sent to the transmission unit 17. In addition, when it is determined that the reception quality (CQI) of the terminal device indicated by the random access preamble is low, reception of a random access response from the base station to the terminal device is awaited for a certain period of time, and random transmission from the base station to the terminal device is performed. When the access response is not received, an instruction to relay the random access preamble to the base station is sent to the transmission unit 17. Further, when instructed from the assignment instruction acquiring unit, an instruction is sent to the response generating unit 16 and the transmitting unit 17.

  When receiving an instruction from the control unit 14, the response generation unit 16 generates a random access response message using the resource input from the resource storage unit 15. The generated random access response message is output to the transmission unit 17. Here, the response generator 16 corresponds to a response signal generator of the present invention.

  The transmission unit 17 transmits the random access response message input from the response generation unit 16 or the random access preamble input from the random access preamble storage unit 12 from the antenna 18 according to the instruction of the control unit 14.

  Next, the operation of the relay station provided with the wireless relay device 10 of the second modification will be described. Also here, a case where two terminal apparatuses (terminal apparatuses A and B) are relayed by two relay stations (relay stations A and B) is illustrated.

  FIG. 10 is a sequence diagram showing the flow of the RACH procedure when the reception quality (CQI) of the terminal device indicated by the random access preamble is low. As shown in FIG. 10, first, the two terminal devices both transmit a random access preamble (message 1) to the base station (S120, S121). In this case, it is assumed that the same signature is used in the random access preambles of the two terminal devices. The random access preamble transmitted from the terminal device A reaches the base station (S120), but the random access preamble transmitted from the terminal device B does not reach the base station and is received by the relay station B (S121). ). Note that the random access preamble transmitted by the terminal device A is also received by the relay station A.

  Since the operation of the terminal device A is the same as that of the first embodiment shown in FIG. 5, the description thereof is omitted here.

  The case of the terminal device B will be described. The relay station B that has received the random access preamble transmitted by the terminal device B has a certain time (FIG. 10) when the reception quality (CQI) of the terminal device indicated by the received random access preamble is low. In FIG. 6, the process waits for a random access response from the base station to the terminal device B to be transmitted.

  If the random access response from the base station to the terminal device B is not received within a certain time, the relay station B relays the received random access preamble to the base station (S125). Thereafter, the relay station B generates a random access response based on the resource allocation instruction (instruction message) received from the base station (S170), and transmits the random access response (message 2) to the terminal device B ( S171). Thereafter, the terminal apparatus B transmits an RRC connection request to the base station via the relay station B (S128, S129). The base station responds to the RRC connection request from the terminal apparatus B via the relay station B. , RRC connection establishment is transmitted (S130, S131).

  FIG. 11 is a flowchart showing an operation flow when the relay station including the wireless relay device 10 receives the random access preamble. As illustrated in FIG. 11, when the relay station receives the random access preamble transmitted by the terminal device (S140), the relay station determines the CQI of the terminal device indicated in the random access preamble (S141). When the CQI is low, it waits for a certain time (S144), and determines whether or not a random access response from the base station is received within the certain time (S145). When a random access response is received from the terminal device at a certain time, the random access preamble is relayed to the base station (S146).

  Thereafter, the relay station receives a resource allocation instruction from the base station to the terminal device (S180), generates a random access response message according to the received resource allocation instruction (S181), and transmits the generated random access response to the terminal device. (S182).

  In the wireless relay device 10 of Modification 2 as described above, when the random access response from the base station is not received within the predetermined determination period and it is determined that the necessity for relaying is high, the wireless relay device 10 receives from the base station. A random access response is generated based on the resource allocation instruction, and the random access response is transmitted to the terminal device. In this way, relaying by the wireless relay device 10 is performed, and reception efficiency in the communication cell is improved. Moreover, according to this, the resource allocation of the terminal device can be centrally managed on the base station side.

  According to the second modification, when the resources allocated to the terminal device are distributed and managed by the base station and the relay station, whether or not the relay station relays the random access preamble to the base station according to the CQI of the terminal device. judge. Therefore, when the CQI of the terminal device is high, the relay station can directly transmit a random access response to the terminal device, thereby reducing unnecessary signaling.

  In addition, when the CQI of the terminal device is low, the relay station waits for a random access response from the base station for a certain period of time, so that only when the random access preamble does not reach the base station, the relay station can Relay to station. Therefore, useless resource consumption due to the base station allocating resources to a plurality of random access preambles can be reduced.

(Second Embodiment)
Next, a wireless relay device according to a second embodiment of this invention will be described with reference to FIGS. Here, the points different from the first embodiment will be mainly described. Therefore, unless otherwise mentioned here, the configuration and operation of the second embodiment are the same as those of the first embodiment.

  FIG. 12 is an explanatory diagram illustrating an example of a positional relationship among a base station, a relay station, and a terminal device according to the present embodiment. As shown in FIG. 12, in this Embodiment, one terminal device (UE) is located in the boundary of the area of two relay stations (RN1, RN3). Therefore, this terminal device can communicate with the base station and can also communicate with two relay stations. That is, since this terminal device is in the area of two relay stations, the signal transmitted from the terminal device to the base station can also be received by the two relay stations.

  FIG. 13 is a diagram illustrating an example of assignment of signatures used in wireless communication. In the present embodiment, signatures 0 to 47 are assigned to nine relay stations (RN1 to 9). In this example, the relay stations are divided into three groups, and signatures are assigned so that adjacent relay stations (for example, RN1 and RN3, see FIG. 12) do not belong to the same group. In addition, signatures are assigned so as to be used depending on the level of reception quality (CQI). It can be said that the signatures 0 to 47 are assigned to the wireless relay device 20.

  Specifically, when the reception quality (CQI) of communication with the relay stations of RN1, 4, and 7 is low, a signature of 40 to 47 is used in the terminal device, and when the reception quality (CQI) is high , 16-23 signatures are used. In addition, when the reception quality (CQI) of communication with the relay stations of RN2, 5, and 8 is low, the terminal device uses a signature of 32 to 39, and when the reception quality (CQI) is high, 8 to Fifteen signatures are used. Further, when the reception quality (CQI) of communication with the relay stations of RN3, 6, 9 is low, the terminal device uses a signature of 24 to 31, and when the reception quality (CQI) is high, 0 to Seven signatures are used.

  Next, the configuration of the wireless relay device 20 according to the second embodiment will be described. FIG. 14 is a block diagram illustrating a configuration of the wireless relay device 20 according to the present embodiment. As shown in FIG. 14, the wireless relay device 20 of the present embodiment is different from the first embodiment of FIG. 1 in that a signature determination unit 23 is provided. That is, the radio relay apparatus 20 according to the present embodiment includes the same reception unit 21, preamble storage unit 22, control unit 24, resource storage unit 25, and response generation unit 26 as in the first embodiment.

  The signature determination unit 23 determines whether the signature used in the random access preamble corresponds to a signature (also referred to as an assigned signature) assigned to the wireless relay device 20. Here, the signature determination unit 23 corresponds to signature determination means of the present invention.

  The transmitting unit 27 relays and transmits the received random access preamble from the antenna 28 to the base station when it is determined that the signature used in the random access preamble is an assigned signature of the wireless relay device 20. Therefore, it can be said that this transmission unit 27 corresponds to the relay transmission means of the present invention.

  The operation of the relay station including the wireless relay device 20 configured as described above will be described with reference to FIGS. 15 and 16. Here, a case where one terminal apparatus is located at the boundary between the areas of two relay stations (RN1, RN3) is illustrated.

  FIG. 15 is a sequence diagram illustrating the flow of the RACH procedure in the second embodiment. As shown in FIG. 15, the terminal apparatus transmits a random access preamble (message 1) to the base station (S200). At this time, it is assumed that the random access preamble transmitted by the terminal device does not reach the base station but is received by the two relay stations.

  The two relay stations determine whether the received signature of the random access preamble is included in the signature group assigned to each relay station by the base station. For example, when the signature of the random access preamble transmitted by the terminal device is included in the signature group assigned to one relay station (RN1), the relay station relays the received random access preamble to the base station ( S201). In this case, the other relay station (RN3) rejects the received random access preamble because the signature of the received random access preamble is not included in the signature group assigned to itself.

  When the base station receives the random access preamble from one relay station (RN1), the base station creates a random access response (message 2) to which T-CRNI and grant are assigned, and transmits the random access response to the terminal device via the relay station ( S202, S203).

  Thereafter, the terminal device transmits an RRC connection request to the base station via the relay station (RN1) (S204, S205), and the base station responds to the RRC connection request from the terminal device with the relay station (RN1). The RRC connection establishment (message 4) is transmitted via (S206, S207).

  FIG. 16 is a flowchart showing an operation flow when the relay station including the wireless relay device 20 receives the random access preamble. As shown in FIG. 16, first, the relay station receives a random access preamble from the terminal device (S210). Next, it is determined whether the received signature of the random access preamble is included in the signature group assigned from the base station (S211).

  If the received random access preamble signature is included in the signature group assigned by the base station, the reception quality (CQI) of the terminal device indicated in the random access preamble is determined (S212).

  If the CQI is high, a random access response message is generated for the received random access preamble (S213), and then transmitted to the random access response terminal device (S214).

  When the CQI is low, it waits for a certain time (S215), and determines whether or not a random access response from the base station is received within the certain time (S216). When a random access response is received from the base station within a certain time, relaying is not performed. On the other hand, when a random access response is received from the terminal device at a certain time, the random access preamble is relayed to the base station (S217).

  If the received random access preamble signature is not included in the signature group assigned from the base station, the received random access preamble is rejected (S218).

  In the wireless relay device 20 according to the second embodiment of the present invention as described above, when one terminal device performs the RACH procedure in the overlapping part of the communication cells of the two wireless relay devices 20 (RN1, RN3). The multiple messages relayed by each wireless relay device 20 are suppressed from being received redundantly by the base station. In this case, the terminal apparatus selects one radio relay apparatus 20 (RN1), and transmits a random access preamble using an allocation signature (for example, signature “40”) of the selected radio relay apparatus 20. Each radio relay apparatus 20 relays and transmits only a message using the assigned signature of the radio relay apparatus 20 to the base station. Thereby, only one radio relay apparatus 20 (RN1) selected as the terminal apparatus performs relay transmission of the message. Therefore, it is possible to prevent a message from one terminal apparatus from being relayed by the plurality of radio relay apparatuses 20, and to suppress useless resource allocation at the base station.

  That is, according to the second embodiment, when a terminal apparatus located at the boundary between two relay station areas transmits a random access preamble, it is included in the signature group assigned by the base station. Only relay random access preambles using signatures. Thereby, it can suppress that both relay stations relay a random access preamble to a base station. Therefore, it is possible to prevent the base station from misinterpreting that a random access preamble using the same signature is transmitted from two terminal apparatuses and allocating resources to two random access preambles from one terminal apparatus. And wasteful resource consumption can be reduced.

(Third embodiment)
Next, a wireless transmission / reception apparatus according to the third embodiment of the present invention will be described with reference to FIGS. Here, the points different from the first embodiment will be mainly described. Therefore, unless otherwise specified here, the configuration and operation of the third embodiment are the same as those of the first embodiment.

  FIG. 17 is an explanatory diagram illustrating an example of a positional relationship among a base station, a relay station, and a terminal device according to the present embodiment. As shown in FIG. 17, in this Embodiment, two terminal devices (UE1, UE2) are located in the edge region of the communication cell (also referred to as area) of the base station. In this example, each terminal device is located at a boundary point between the areas of the base station and each relay station (RN1, RN2).

  Next, the configuration of the wireless transmission / reception device 30 according to the third embodiment will be described. FIG. 18 is a block diagram illustrating a configuration of the wireless transmission / reception device 30 according to the present embodiment. As illustrated in FIG. 18, the wireless transmission / reception apparatus 30 includes a reception unit 31, a random access preamble acquisition unit 32 (also simply referred to as a preamble acquisition unit), and a determination unit 33. The wireless transmission / reception apparatus 30 includes a resource storage unit 34, a random access response generation unit 35 (also simply referred to as a response generation unit), and a transmission unit 36.

  The receiving unit 31 receives a message transmitted from the terminal device from the antenna 37 in the RACH procedure. Specifically, the receiving unit 31 receives a random access preamble, an RRC connection request, and the like from the terminal device and the relay station. Here, the receiving unit 31 corresponds to the message receiving means of the present invention.

  The preamble acquisition unit 32 acquires the random access preamble input from the reception unit 31 and outputs the random access preamble to the determination unit 33.

  The determination unit 33 determines the signature of the random access preamble input from the preamble acquisition unit 32, and determines the relay station that relayed the random access preamble. When the random access preamble of the same signature is received from different relay stations, the determination unit 33 instructs the random access response generation unit 35 to use different T-CRNI and uplink resources ( grant). Here, the determination unit 33 corresponds to the determination unit of the present invention.

  The resource storage unit 34 stores resources (T-CRNI, grant) to be allocated to terminal devices that have attempted random access. This resource is allocated in advance from the base station.

  The response generation unit 35 generates a random access response message using the resource input from the resource storage unit 34. When instructed by the determination unit 33, the response generation unit 35 generates a random access response message in which different T-CRNIs and grants are assigned to two random access preambles using the same signature. Here, the response generation unit 35 corresponds to a response generation unit of the present invention. The generated random access response message is output to the transmission unit 36.

  The transmission unit 36 transmits the random access response message input from the response generation unit 35 from the antenna 37. Here, the transmission unit 36 corresponds to the transmission means of the present invention.

  The operation of the base station provided with the radio transceiver 30 configured as described above will be described with reference to FIGS. 19 and 20. Here, a case where messages from two terminal devices (terminal devices A and B) are respectively relayed by two relay stations (relay stations A and B) is illustrated.

  FIG. 19 is a sequence diagram showing the flow of the RACH procedure in the third embodiment. As shown in FIG. 19, first, the two terminal devices both transmit a random access preamble (message 1) to the base station (S300, S301). In this case, it is assumed that the same signature is used in the random access preambles of the two terminal devices. Also, it is assumed that the random access preambles transmitted by the two terminal devices do not reach the base station and are received by the two relay stations, respectively.

  The relay station that has received the random access preamble transmitted by the terminal device relays the received random access preamble to the base station (S302, S303). When the base station receives random access preambles using the same signature from the two relay stations, the base station T is a temporary ID used for communication between the terminal device and the base station for each random access preamble. -Create a random access response (message 2) to which CRNI and a grant (scheduling grant) indicating an uplink resource used by the terminal device to transmit a message to the base station next is assigned to each of the two relay stations. Transmit (S304, S305). When each relay station receives a random access response from the base station, each relay station forwards the random access response to the terminal device (S306, S307).

  After that, each terminal device transmits an RRC connection request (message 3) to the base station via each relay station (S308 to S311). In response to the RRC connection request from each terminal device, the base station transmits RRC connection establishment (message 4) via each relay station (S312 to S315).

  FIG. 20 is a flowchart showing an operation flow when the base station including the wireless transmission / reception device 30 receives a random access preamble. As shown in FIG. 20, first, the base station receives random access preambles relayed from two different radio relay apparatuses at the same timing (S320). Next, the base station determines the signatures of the two random access preambles (S321). When the signatures are the same, a random access response message in which different resources (T-CRNI, grant) are assigned to each random access preamble is created (S322). If the signatures are different, resources are allocated to each random access preamble (S323). Thereafter, the created random access response message is transmitted to the relay destination of each random access preamble (S324).

  In the wireless transmission / reception device 30 according to the third embodiment of the present invention, when two terminal devices simultaneously transmit random access preambles using the same time slot and the same signature when performing the RACH procedure, Two random access preambles relayed by the relay device may be received simultaneously by the wireless transmission / reception device 30. In this case, in the wireless relay device, resources (for example, frequencies) assigned to the random access preamble are used when the random access preamble is relayed and transmitted. Thereby, the radio | wireless transmission / reception apparatus 30 can discriminate | determine the radio relay apparatus which relay-transmitted the random access preamble based on the resource, and transmits a different random access response for every radio relay apparatus. Therefore, even when two terminal devices perform a calling procedure at the same time using the same time slot and the same signature, the probability of occurrence of a collision between the two terminal devices can be reduced.

  That is, according to the third embodiment, even when two terminal apparatuses transmit random access preambles using the same signature, they differ for random access preambles relayed from different relay stations. A random access response is created by allocating resources. Then, by transmitting these random access responses to the terminal devices via the respective relay stations, it is possible to suppress the collision of random access preambles, and the two terminal devices can receive the random access responses correctly. it can. Therefore, even if the entire coverage is expanded by arranging the relay station, it is possible to suppress the occurrence probability of the random access preamble collision.

  The embodiments of the present invention have been described above by way of example, but the scope of the present invention is not limited to these embodiments, and can be changed or modified according to the purpose within the scope of the claims. is there.

  As described above, the wireless relay device according to the present invention has an effect that it is possible to suppress the allocation of useless resources at the base station, and is useful, for example, in a mobile communication system.

The block diagram which shows the structure of the radio relay apparatus and terminal device in 1st Embodiment Explanatory drawing which shows the positional relationship of the base station in 1st Embodiment, a relay station, and a terminal device Explanatory drawing of the reception quality of the signal from the base station or relay station received by the terminal device Sequence diagram showing the flow of the RACH procedure when CQI is high in the first embodiment Sequence diagram showing the flow of the RACH procedure when CQI is low in the first embodiment The flowchart which shows the flow of the relay process in 1st Embodiment Sequence diagram showing the flow of RACH procedure when CQI is high in Modification 1 Flow diagram showing the flow of relay processing in Modification 1 The block diagram which shows the structure of the radio relay apparatus in the modification 2. Sequence diagram showing the flow of the RACH procedure when CQI is low in Modification 2 Flow diagram showing the flow of relay processing in Modification 2 Explanatory drawing which shows the positional relationship of the base station in 2nd Embodiment, a relay station, and a terminal device The figure which shows an example of allocation of the signature used for radio | wireless communication The block diagram which shows the structure of the radio relay apparatus in 2nd Embodiment The sequence diagram which shows the flow of the RACH procedure in 2nd Embodiment The flowchart which shows the flow of the relay process in 2nd Embodiment Explanatory drawing which shows the positional relationship of the base station in 3rd Embodiment, a relay station, and a terminal device The block diagram which shows the structure of the radio | wireless transmitter / receiver in 3rd Embodiment. The sequence diagram which shows the flow of the RACH procedure in 3rd Embodiment The flowchart which shows the flow of the transmission / reception process in 3rd Embodiment Sequence diagram for explaining a conventional RACH procedure Explanatory drawing showing an example of a relay station Sequence diagram showing the flow of the RACH procedure

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio relay apparatus 11 Receiving part 12 Preamble memory | storage part 13 Determination part 14 Control part 15 Resource memory | storage part 16 Response generation part 17 Transmission part 19 Assignment instruction | indication acquisition part 20 Radio relay apparatus 21 Receiving part 22 Preamble memory | storage part 23 Signature determination part 24 Control Unit 25 resource storage unit 26 response generation unit 27 transmission unit 30 wireless transmission / reception device 31 reception unit 32 preamble acquisition unit 33 determination unit 34 resource storage unit 35 response generation unit 36 transmission unit

Claims (14)

A wireless relay device that is arranged in a communication cell of a base station and relays wireless communication performed between the base station and a terminal device,
Message receiving means for receiving a message communicated between the terminal apparatus and the base station using a common channel in the RACH procedure of the terminal apparatus;
Relay determining means for determining whether to perform wireless communication relay between the terminal device and the base station based on the reception status of the message;
Message transmitting means for transmitting a message according to the determination to the terminal device using the common channel;
A wireless relay device comprising: The message receiving means can receive a preamble signal transmitted from the terminal apparatus to the base station in the RACH procedure, and the preamble signal includes reception quality information indicating a level of reception quality in the terminal apparatus. And
2. The radio according to claim 1, wherein the relay determination unit determines whether to perform radio communication relay according to the level of the reception quality based on reception quality information included in the preamble signal. Relay device.   The wireless relay according to claim 2, further comprising response signal generation means for generating a response signal for the preamble signal received by the message reception means when it is determined that the reception quality is high. apparatus.   The radio relay apparatus according to claim 2, further comprising: a relay transmission unit that relays and transmits the preamble signal received by the message reception unit to the base station when it is determined that the reception quality is high. The message receiving means can receive a preamble signal transmitted from the terminal apparatus to the base station in the RACH procedure, and a response signal transmitted from the base station to the terminal apparatus as a response to the preamble signal,
The relay determination means, after receiving the preamble signal, when it is determined that the reception quality is low, a determination period until a reference time indicating a reference of necessity of relaying the wireless communication elapses 5, wherein it is determined whether or not the response signal has been received, and whether or not to perform relaying is determined according to whether or not the response signal is received. The wireless relay device described.   The relay transmission means for relaying and transmitting the preamble signal received from the terminal device to the base station when it is determined that the response signal is not received within the determination period. The wireless relay device described.   Response signal generation means for generating a response signal for the preamble signal based on a response generation instruction signal received from the base station as a response to the preamble signal relay-transmitted from the relay transmission means The wireless relay device according to claim 6. A wireless relay device that is arranged in a plurality of communication cells of a base station and relays wireless communication performed between the base station and a terminal device,
The wireless relay device is
Message receiving means for receiving a message communicated between the terminal apparatus and the base station using a common channel in the RACH procedure of the terminal apparatus;
Signature determination means for determining whether the signature used in the communication of the message is an assigned signature assigned to the wireless relay device;
Relay transmission means for relaying the message received from the terminal device to the base station when it is determined that the signature is the assigned signature;
With
The wireless relay device is characterized in that at least one signature is assigned to the wireless relay device, and the at least one signature is assigned to adjacent wireless relay devices so as not to overlap. A wireless transmission / reception device capable of wireless communication with a plurality of terminal devices via a plurality of wireless relay devices,
Message receiving means for receiving a message transmitted from the terminal device using a common channel in the RACH procedure of the terminal device;
A discriminating means for discriminating a radio relay device that relayed the message based on resources allocated to each radio relay device;
A response generating unit configured to generate a plurality of response signals different for each wireless relay device as a response to the plurality of messages when it is determined that messages from the plurality of terminal devices are relayed by different wireless relay devices; ,
A plurality of response signals different for each wireless relay device, response transmission means for transmitting using the common channel;
A wireless transmission / reception apparatus comprising: In a radio relay device arranged in a communication cell of a base station, a radio relay method for relaying radio communication performed between the base station and a terminal device,
Receiving a message communicated using a common channel between the terminal device and the base station in the RACH procedure of the terminal device;
Based on the reception status of the message, determine whether to relay wireless communication between the terminal device and the base station,
A wireless relay method, wherein a message according to the determination is transmitted to the terminal device using the common channel. A wireless relay method for relaying wireless communication performed between the base station and a terminal device in each of a plurality of wireless relay devices arranged in a communication cell of a base station,
The wireless relay device is assigned at least one signature, and the wireless relay devices adjacent to each other are assigned so that the at least one signature does not overlap,
The wireless relay method is:
Receiving a message communicated using a common channel between the terminal device and the base station in the RACH procedure of the terminal device;
Determining whether the signature used in the communication of the message is an assigned signature assigned to the wireless relay device;
A wireless relay method comprising: relaying and transmitting the message received from the terminal device to the base station when it is determined that the signature is the assigned signature. In a wireless transmission / reception device capable of wireless communication with a plurality of terminal devices via a plurality of wireless relay devices,
Receiving a message transmitted from the terminal device using a common channel in the RACH procedure of the terminal device;
Based on the resources allocated to each wireless relay device, determine the wireless relay device that relayed the message,
When it is determined that messages from a plurality of the terminal devices are relayed by different wireless relay devices, a plurality of response signals different for each of the wireless relay devices are generated as responses to the plurality of messages,
A wireless transmission / reception method comprising: transmitting a plurality of response signals different for each wireless relay device using the common channel.   A relay node comprising the wireless relay device according to claim 1.   A base station comprising the radio transmission / reception device according to claim 9.

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