JP5542944B2 - RADIO COMMUNICATION SYSTEM HAVING RELAY DEVICE AND RADIO RESOURCE ALLOCATION METHOD - Google Patents

Description

  The present invention relates to a radio communication system having a base station, a terminal, and a relay device, and more particularly to a technique for managing radio resources used by the base station and the relay device for data communication between the base station and the terminal.

  In a mobile radio communication system, a fixed station (base station) is arranged assuming a movement range of a mobile station (terminal). Specifically, an area (cell) in which each base station can communicate with a terminal is overlapped by arranging a plurality of base stations, and no matter where the terminal is located within the assumed range, A base station is arranged so that communication is possible. In practice, however, there are areas (dead zones) where the terminal cannot communicate with the base station due to restrictions on the location of the base stations and the influence of shielding such as buildings. In order to reduce the dead zone, a relay device that relays wireless communication between a base station and a terminal has been introduced. This relay device is an Amplify & Forward type (AF type) relay device and has a function of amplifying and transmitting a received signal.

  Although the AF type relay apparatus does not perform baseband signal processing, the apparatus configuration is simplified. However, since the noise at the receiving end is also amplified, the signal power-to-noise ratio (Signal to Noise Ratio, SNR) of the relayed signal is increased. ) Is never higher than the SNR at the receiving end of the relay apparatus. On the other hand, the baseband signal processing is performed in the relay device, the received signal is once decoded and returned to the data bit sequence, and the data bit sequence is encoded again, so that the received noise component of the relay device can be removed. Decode & Forward A type (DF type) relay apparatus is known. Thereby, the SNR at the transmission end of the relay apparatus can be made higher than the SNR at the reception end.

  Toward IMT-Advanced, 3GPP (3rd Generation Partnership Project), a standardization organization for mobile communications, is proceeding with standardization of LTE-Advanced (hereinafter abbreviated as LTE-A), a successor to LTE (Long Term Evolution). ing. In LTE-A, in order to improve the cell average frequency utilization efficiency and the cell edge frequency utilization efficiency, introduction of a DF type relay device is being studied. Similarly, the standardization organization IEEE (Institut of Electrical and Electronics Engineers) is the successor standard of WiMAX (Worldwide Interoperability for Microwave Access), which is the standardization of IEEE8016m, which is a successor of the IEEE standard 1616. Has been.

  In 3GPP, a relay device is defined as a node having a wireless backhaul line with a donor base station (see Chapter 9 of Non-Patent Document 1). According to Non-Patent Document 1, there are two types of wireless backhaul lines, Inband backhaul and Outband backhaul, which are under study, and the former is a part of wireless communication resources used for data communication and is a wireless communication resource for backhaul lines. The latter secures a radio communication resource for the backhaul line separately from the radio communication resource used for data communication. The latter is easier to manage wireless communication resources, but as an extreme example, if there is no need to use any backhaul lines, the wireless communication resources allocated for backhaul lines cannot be diverted to data communication. It has the property that the frequency utilization efficiency tends to decrease. In addition, since IEEE aims to be completely backward compatible with WiMAX, the relay device is naturally an inband backhaul (see Section 8.8.4 of Non-Patent Document 2).

  The form of the relay device is roughly divided into two types, an independent type and a dependent type. The independent relay device can independently perform H-ARQ (Hybrid Automatic Repeat reQuest), which is radio resource allocation and packet retransmission control, and has almost the same function as a conventional base station. have. The difference from the base station is that data exchange with the network depends on other base stations wirelessly. The subordinate type relay device depends on other base stations including resource allocation and resource control including H-ARQ, and can be said to be a simple DF type relay device.

JP 2004-166225 A

3GPP, “Further Advances for E-UTRA Physical Layer Aspects”, TR 36.814, v1.0.0, 2009/02. IEEE Standard, “Foreland Standard, Local and Metropolitan Area Network Networks, Part 9: Air Interface for Fixed 9”, and “Early for the World”. 3GPP, “Physical Channel and Modulation (Release 8)”, TS 36.211, v8.7.0, 2009/06. 3GPP, “Multiplexing and channel coding (Release 8)”, TS36.212, v8.7.0, 2009/06. 3GPP, “Physical layer procedures (Release 8)”, TS36.213, v8.7.0, 2009/06.

  A wireless communication system in which a relay device is introduced is shown in FIG. When the relay apparatus 103 is introduced into a wireless communication system in which the base station 101 and the terminal 102 perform data communication, in addition to the wireless communication path (first wireless communication path) 104 between the base station and the terminal, the wireless communication between the relay apparatus and the terminal is performed. A communication path (second radio communication path) 105 and a radio communication path (third radio communication path) 106 between the base station and the relay device are generated. That is, as the wireless communication route between the base station and the terminal, the first route using the first wireless communication channel 104 and the second route using the second wireless communication channel 105 and the third wireless communication channel 106 are used. And two routes occur.

  In 3GPP, as described in Chapter 9 of Non-Patent Document 1, a relay device is defined as a node having a wireless backhaul line with a donor base station, and the relay device is configured to perform downlink (base station to terminal) communication and uplink (terminal to terminal). (Base station) Since both communications are relayed, the number of senders in the entire system increases due to the introduction of a relay device. Therefore, if the relay apparatus and the base station or terminal perform transmission independently using radio resources, the communication quality of the entire system may deteriorate due to interference.

  For example, Patent Document 1 discloses a technique for assigning different radio resources to each traffic in a system having a plurality of traffic sources. In Patent Document 1, communication of a second source occurs in a situation where a first traffic source that performs regular communication and a second traffic source that performs non-stationary communication transmit data via a base station. The control device reserves the radio resource of the base station for the second source, and the radio resource is fixedly secured until the communication of the second source is completed. The actual traffic volume is not taken into account. In other words, as in the case of Outband backhaul, when the traffic volume of the second source is smaller than the fixedly secured radio resource amount, the usage efficiency of the radio resource may be reduced.

  In order to solve at least one of the above-described problems, in one aspect of the present invention, the base station communicates with the second wireless communication path for communication between the relay device and the terminal. Than the time corresponding to the radio resource assigned to at least one of the third wireless communication path for performing communication and the first wireless communication path for direct communication between the base station and the terminal. At the time when communication on the second wireless communication path is performed, the base station performs communication avoiding the allocated wireless resource.

  In another aspect, the success or failure of communication on the third wireless communication path is fed back to the relay device, and in the communication on the third wireless communication path that has failed in communication, transmission is performed on the second wireless communication path. Release the allocated radio resources.

  In the wireless communication system having the relay device, it is possible to improve the wireless communication resource utilization efficiency.

Wireless communication system incorporating a relay device Configuration of OFDM data transmitted from base station Configuration of OFDM data transmitted from relay station Data structure at a certain time transmitted from the base station Example format of data sent from base station to relay station Sequence diagram of wireless communication system Conceptual diagram of radio resource allocation assigned by base station Conceptual diagram of radio resource allocation assigned by base station Conceptual diagram of radio resource allocation assigned by base station Example of functional block configuration of base station Base station device configuration example Configuration example of a device that realizes channel response estimation of a plurality of wireless communication channels using a plurality of reference signals overlapping in the same time frequency Functional block configuration example of a relay device Functional block configuration example for downlink communication of relay device Functional block configuration example regarding uplink communication of relay device Device configuration example of relay device Functional block configuration example of terminal Device configuration example of the terminal device 102 Example of operation flowchart of relay device Example of format for receiving data buffer of relay device Example of operation flowchart of base station regarding release of reserved resource of relay device Resource reservation status management table example Sequence diagram of wireless communication system in second embodiment The figure which shows the relationship between the transfer time in 2nd embodiment, and the timing which releases the resource of a 3rd radio | wireless communication path. Details of transfer time determination processing performed by the base station in the modification of the second embodiment Relay device management table example

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a wireless communication system according to a first embodiment of the present invention. The wireless communication system includes a base station 101, at least one terminal 102, 107, 108, and at least one relay apparatus 103. When the relay apparatus 103 is introduced into a wireless communication system in which the base station 101 and the terminal 102 perform data communication, in addition to the wireless communication path (first wireless communication path) 104 between the base station and the terminal, the wireless communication between the relay apparatus and the terminal is performed. A communication path (second radio communication path) 105 and a radio communication path (third radio communication path) 106 between the base station and the relay device are generated. That is, as the wireless communication route between the base station and the terminal, the first route using the first wireless communication channel 104 and the second route using the second wireless communication channel 105 and the third wireless communication channel 106 are used. And two routes occur. In FIG. 1, the base station and the terminal 109 communicate with each other because of the first wireless communication path. Further, the relay apparatus 103 and the terminals 107 and 108 communicate with each other through the second wireless communication path 105. In the third wireless communication path 106, the base station 101 and the relay device 103 communicate with each other. The first wireless communication path 104 is, for example, a direct communication between the base station and the terminal. Therefore, the direct link, the second wireless communication path 105 is, for example, an access link, and the third wireless communication path is, for example, a backhaul link. Correspond.

  Reference numerals 201, 202, and 203 denote configurations of radio resources allocated to the first radio communication path 104, the second radio communication path 105, and the third radio communication path 106, respectively. In this embodiment, the Inband Backhaul described in the background art is applied, and wireless communication resources transmitted and received by the base station are allocated from wireless resources shared by the first wireless communication path 104 and the third wireless communication path 106. It is done.

  Here, since relay apparatus 103 relays both downlink (base station to terminal) communication and uplink (terminal to base station) communication, the number of transmitters in the entire system increases due to the introduction of the relay apparatus. For this reason, when the relay device and the base station or terminal perform transmission independently, there is a possibility that the communication quality of the entire system is deteriorated due to interference. On the other hand, when the base station and the relay apparatus perform transmission exclusively using radio resources, it is possible to avoid downlink communication interference. Hereinafter, the description will be made focusing on downlink communication, but the same can be said for uplink communication.

  FIG. 2 shows details of the configuration of OFDM data arranged in frequency resources shared between the wireless communication paths in FIG. 2A shows a configuration of OFDM data transmitted from the base station, and FIG. 2B shows a configuration of OFDM data transmitted from the relay apparatus.

  FIG. 2A shows a configuration of OFDM data generated by the base station and transmitted from the base station. This data is received by the relay device or directly by the terminal. In this resource configuration, the vertical axis is a frequency axis, and the horizontal axis is a time axis, which are arranged for one or more subcarrier and OFDM symbol resources, respectively. A control signal 303 is a control signal for the relay apparatus, and a control signal 301 is a control signal for a terminal that performs direct communication.

  The control signals 301 and 303 are respectively the identifier ID of the destination device and the transmission time, the frequency resource to be used and the terminal to which data is to be transmitted, the transmission time, the frequency resource to be used and the MCS (Modulation and Coding Scheme: Coding and modulation system). Then, based on the frequency resource included in the control signal, either data signal 302 or 304 corresponding to the frequency resource is demodulated and decoded by relay apparatus 103 or terminal 108 that directly communicates with the base station, and data is received. That is, the control signal 303 is information regarding resources allocated to the third wireless communication path, and the control signal 301 is information regarding resources allocated to the first wireless communication path.

  With the resource configuration as shown in FIG. 2A, first, the base station 101 first transmits a terminal to which data is to be transmitted in the first channel data signal 302, a transmission time, a frequency resource to be used, and an MCS (Modulation and Coding Scheme). Modulation method) is determined. This operation is generally called scheduling. Next, for each of the determined transmission targets, a first communication path control signal 301 indicating the ID and transmission time of the destination terminal, the frequency resource to be used, and the modulation scheme information is generated and notified to the terminal.

  The terminal 108 receives the first channel control signal 301 and determines whether or not there is a resource allocation addressed to itself, and if there is a resource allocation, the terminal 108 transmits the first channel data signal 302 transmitted at the corresponding time. Data is received by demodulating / decoding specified frequency resources.

  Similarly, the relay device 103 receives the control signal 303 and determines whether or not there is resource allocation addressed to itself. Then, when there is resource allocation, the relay device 103 demodulates and decodes the data signal 304 transmitted through the third communication channel and the frequency resource specified by the control signal 301 at the time corresponding to the control signal 303. To receive data.

  FIG. 2B shows a configuration of radio resources related to communication via the relay device.

  2B includes a control signal 305 related to the resource of the second wireless communication path and a data signal 306 communicated on the second wireless communication path. The data signal 304 is demodulated / decoded, and the relay apparatus obtains information related to the resource of the second wireless communication path and data to be transmitted in the resource. Information regarding the resources of the second wireless communication path is notified to the terminal by the control signal 305. The relay device encodes and modulates data to be transmitted in accordance with the control signal 305, generates a data signal 306, and assigns the data to a specified frequency and time resource. The above is the description of FIGS. 2A and 2B.

  FIG. 3 shows a data structure at a certain time transmitted from the base station. 3, the relationship between the control signals 301 and 302 and the data signals 303 and 304 transmitted from the base station in FIG. 2A and the resources 201 and 203 allocated to the wireless communication paths 104 and 106 in FIG. explain. At a certain time, a control signal 301 and a data signal 302 are arranged in the resource 201 allocated to the first wireless communication path 104. On the other hand, at a certain time, the control signal 301 and the data signal 302 are arranged in the resource 203 allocated to the first wireless communication path 106. Although not shown, a control signal 305 and a data signal 306 are arranged in the resource 202. As described with reference to FIG. 2B, the data signal 304 includes data and transfer conditions that the relay apparatus should transfer to the terminal 102 and the terminal 107 at a future time from that time.

FIG. 4 shows a configuration example of the third wireless channel data signal 304 for the relay device. Information of the second wireless channel control signal 305 for the data transmitted by the relay device using the second wireless channel data signal 306, that is, the ID 401 and the transmission time 402 of the destination terminal of the first transmission data, the frequency resource 403 to be used, and the MCS 404 , And the first transmission data main body 405 are stored, and similar information is stored for each of the transmission data 306 thereafter.
After mapping the configured data to the third wireless channel data signal 304, the base station 101 generates a third wireless channel control signal 303. The configuration 303 is the same as that of the first wireless channel control signal 301, and can be transmitted simultaneously with the first wireless channel control signal 301 as shown in FIG. 2B.

  FIG. 5 shows a sequence diagram of the wireless communication system. First, the base station 101 performs radio resource allocation 601 at time t1 roughly in three steps.

  That is, first, a terminal and a radio resource that are set as destinations in the second radio communication path at a future time are determined. Here, for example, radio resource allocation at time t2 is performed. In the first step, it is necessary to predict the communication quality of the terminal's second wireless communication channel at a future time. For example, this allows the terminal to feed back the current communication quality of the second wireless communication channel to the terminal. It can be estimated by taking into account the amount of future fluctuations predicted from the mobility and past communication conditions. In addition, the amount of transmission data to be generated in the future may be predicted based on the application used by the terminal, and the amount of radio resources to be reserved may be estimated. In addition, the first response may be made in response to the QoS (Quality of Service) request of the application. The route and the second route may be switched. In addition, in order to avoid radio resources being occupied only by communication on the second wireless communication path, the communication quality of the first wireless communication path at a future time is predicted and compared in the same manner as described above. Thus, an upper limit may be set for the total amount of radio resources allocated to the second radio communication path.

  Second, the amount of data to be transmitted to the relay device on the third wireless communication path at time t1 is calculated from the transmission data amount of the second wireless communication path determined in the first step. Thirdly, assignment of radio resources for the first radio communication path and the third radio communication path is performed under the constraint that the entire data amount of the third radio communication path calculated in the second step is transmitted. As described above, since the Inband Backhaul is targeted, the first wireless communication path and the third wireless communication path share wireless resources. When the resource assignment 601 is completed, the base station 101 configures the resource assignment information at the future time and the transmission data of the second wireless communication path as the data of the third wireless communication path (602). At this time, even if the data of the third wireless communication path is individually configured for each terminal that receives data through the second wireless communication path at the future time, the relay device that is the transmission source of the second wireless communication path You may collect it every time. Next, the base station 101 transmits resource allocation information 603 and data 604 to the terminal 108 and the relay device 103 according to the resource allocation of the first radio communication path and the third radio communication path determined by the resource allocation 601. The resource allocation information 603 corresponds to the control signal 303 in FIG. 2A and 402 to 404 in FIG. Data 604 corresponds to data signal 304 in FIG. 2A and 405 in FIG. The relay apparatus receives resource allocation information 603. The success or failure of reception of the data 604 is determined according to the received resource allocation information (605). Then, the relay device 103 notifies the base station 101 of the reception result that is the determination result (1101). For example, when reception is successful, the reception result is ACK indicating success, and when reception fails, it is NACK. Relay apparatus 103 feeds back ACK or NACK to base station 101.

  If the reception is successful, the relay device 103 acquires the time and resource information and transmission data for transmission on the second wireless communication path (606). Here, an example in which transmission at time t2 is designated is shown.

  The operation of the radio resource allocation 607 at time t2 is almost the same as the radio resource allocation 601 at time t1. The radio resources that can be allocated to the transmission of the first and third radio communication paths are the radio resources allocated for the transmission of the second radio communication path at the time t2 in the first step of the radio resource allocation 601 at the time t1. The difference is that it excludes resources. This is to avoid interference by using exclusive radio resources between the relay apparatus and the base station as described above. When the system is regularly operated, the radio resource allocation of the base station basically takes the form of radio resource allocation 607. If the relay apparatus fails in reception as a result of the determination in 606, the subsequent processing is interrupted, and thus nothing is transmitted to the terminal 1 (102).

  Then, resource allocation information 608 and data 609 of the second wireless communication path are transmitted to the terminal. Like the control signal 305 of FIG. 2B, the resource allocation information 608 may be transmitted by the base station or the relay device, and the data 609 is transmitted by the relay device. The terminal receives the data of the second wireless communication path in FIG. 2B according to the resource allocation information 608.

On the other hand, the base station 101 receives a reception result 1101 of data addressed to the relay apparatus at time t1 from the data transmitted by the base station from the relay apparatus, and performs a resource allocation operation 607 according to the reception result 1101.
That is, when the reception result indicates failure, it is recognized that the resource reserved for the second wireless communication path is not used in the data 604, the resource is released, and the resource allocation operation 607 is performed. As a result, the base station 101 can transmit data to the terminal 2 using the released resources, and directly transmits the resource allocation information 1104 and the data 1105 to the terminal 2.

On the other hand, if the reception result has not been received, the base station 101 determines that the resource reserved for the second wireless communication path remains allocated and the other resources remain the same, regardless of the reception result as in the resource allocation 601. Resources are allocated (607).
Note that the terminal 108 receives the transmission target data at the time t2 in the first wireless communication path using the resource allocation information 603 and the data signal 604. FIG. 5 describes the control between one base station and a relay device. However, when a plurality of relay devices are connected to the base station, each relay device and the base station are independently illustrated. 5 may be performed.

  6, FIG. 7, and FIG. 8 show conceptual diagrams of radio resource allocation assigned by the base station. FIG. 6 shows a conceptual diagram of resource allocation 601 and 607 in the base station 101 in FIG. 5 including radio resource reservation. The upper part of “resource allocation of base station” indicates resource allocation for the base station to perform transmission to the relay apparatus and the terminal, and at the same time indicates actual resource usage. The lower part shows frequency resources at a future time that the base station reserves for transmission on the relay device, that is, the second wireless communication path.

In the figure, the third wireless communication channel B (B ackhaul Link), D is the first wireless communication path (D irect Link), the radio resource A, each of which is used and reserved in the second wireless communication path (A ccess Link) Indicates. In this example, the transfer time is 5 hours, and the operation will be described focusing on the resource allocation operation of the base station at time 1.

  The base station 101 first allocates the resource 801 of the second wireless communication channel at time 6, secures the resource 802 for transmitting the resource allocation information and transmission data through the third wireless communication channel, and transfers to the relay device. Send data. The relay apparatus grasps the radio resource 803 to be transmitted at time 6 based on the data received by the resource 802. Of course, 801 and 803 match. Further, at time 6, the base station 101 allocates the resource 804 of the second wireless communication channel at time 11, and secures a resource 805 for transmitting the resource allocation information and transmission data through the third wireless communication channel. The data is transmitted to the relay device.

  However, since the resource 803 is scheduled to be transmitted by the relay device, an area excluding the resource 803 from the whole is allocated to the resource 805 and the resource 806 used for data transmission of the first wireless communication path.

  FIG. 7 shows a case where the relay apparatus fails to receive data on the third wireless communication path at processing time 1 at 605 in FIG. In this case, since the frequency resource to be transmitted at time 6 cannot be detected, the relay apparatus 103 does not perform transmission using the resource 803 at the resource 803 at time 6. On the other hand, when the reception result is not notified from the relay apparatus 103, the base station 101 recognizes the resource 803 as an allocated resource because the relay station 103 is scheduled to transmit at the time t6. Therefore, the radio resource allocation 607 in the base station 101 is performed using resources other than the resource 803. Therefore, the resource 803 remains unused by the base station and the relay apparatus, and resource utilization efficiency is reduced.

  On the other hand, FIG. 8 shows the resource allocation when the relay apparatus 103 fails to receive the data to be transferred to the terminal before the resource allocation 607 at a certain time and the base station receives notification of the failure. It is a conceptual diagram. The base station resource allocation operations 801, 802, and 804 to 806 are the same as those in FIG. The relay device decodes the data of the third wireless communication channel transmitted by the resource 802, and the information 1001 is fed back to the base station when the reception success / failure is determined, and the information 1001 indicates a reception failure. In this case, the base station releases the resource 803 scheduled for transmission of the relay device for its own transmission, that is, transmission of the first wireless communication path or the third wireless communication path, so that it can be reused ( 1002) The point is different. In FIG. 8, the time required for the relay device to complete the decoding of the data on the third wireless communication path and determine whether or not the reception is successful is set to 3 hours. That is, the success or failure of reception of the third wireless communication path transmitted at time 1 is determined at time 4. This is the description of FIGS. 6 to 8.

  The detailed configuration of each device in FIG. 5 will be described below.

  FIG. 9 is a functional block configuration example of the base station 101, and FIG. 10 is a device configuration example of the base station 101. The wireless front end unit 1401 includes an antenna, a duplexer, a power amplifier, a low noise amplifier, an up converter, a down converter, analog-digital conversion, and digital-analog conversion. The radio front end unit 1401 transmits and receives radio frequency signals. The uplink reception baseband signal is subjected to FFT processing at 1402, and data symbols and reference signal symbols are separated at 1403.

  The propagation path response estimation unit 1404 performs response estimation of the uplink first wireless communication path and the uplink third wireless communication path for the reference signal symbols separated in 1403. For estimation of the propagation path response, a known reference signal symbol is used on both the transmitting and receiving sides (terminal and base station, relay device and base station). If the reference signal symbol does not change with time, propagation path response estimation section 1404 holds a fixed and known reference signal symbol sequence in a memory (for example, storage device 1505 in FIG. 10), and changes with time. In this case, propagation path response estimation section 1404 generates a reference signal symbol sequence according to the reference signal symbol sequence rules shared between the transmission side and the reception side.

  In addition, when a plurality of reference signal symbol sequences having low cross-correlation are multiplexed at the same time frequency, that is, terminals, relay devices, or reference signal symbol sequences having different terminals and relay devices are transmitted at the same time frequency. 11, the received reference signal symbol sequence is stored in the middle-stage register 1604 so that the right side is the head as shown in FIG. 11, and the complex conjugate of the known first reference signal symbol sequence is similarly stored in the upper stage. The register 1601 stores the complex conjugate of the known second reference signal symbol series in the lower shift register 1605 so that the right side is first.

  In this state, as shown in the figure, adder 1603 and multiplier 1602 perform multiplication and addition, respectively, so that a propagation path response to the first reference signal symbol and a propagation path response to the second reference signal symbol are respectively obtained. Can be acquired. Here, the received reference signal symbol sequence is input from 1403, and the known first reference signal symbol and the second reference signal symbol are transmitted from a memory for recording a fixed sequence used by 1404 or in the transmission side within 1404. The result generated according to the rules of the reference signal symbol sequence shared on the receiving side is input.

  The communication quality estimation unit 1405 estimates the communication quality of each of the uplink first radio communication channel and the uplink third radio communication channel based on the propagation path estimation result of 1404, and inputs it to the base station control block 1411. The simplest method of communication quality estimation assumes that noise power and interference power are fixed values, the square of the propagation path estimation result estimated in 1404 is the desired signal power, and the value obtained by dividing the desired signal power by the fixed value is SINR. A method of treating as (Signal to Interference plus Noise Ratio) and converting it to Shannon capacity can be mentioned. However, in this method, since the estimation of the communication quality is wrong when the assumption is different from the actual, further outer loop control is often performed. This is because, for example, data communication is repeated using a fixed value set with the expectation that the packet error rate of the data series will be a certain value (for example, set to 1% or 0.1%), and the actual packet error rate Is larger than the expected value, the sum of the actual noise power and interference power is considered to be larger than the fixed value, so the fixed value is increased. Since the sum of the values is considered to be smaller than the fixed value, the fixed value is reduced.

  The weight calculation unit 1406 is a reception weight calculation using the propagation path estimation result of 1404. The purpose of the reception weight is the separation of the received multiple spatial layers and the phase correction of each spatial layer. Known reception weight calculation algorithms include ZF (Zero Forcing) and MMSE (Minimum Mean Square Error).

  Spatial layer division section 1407 multiplies the data symbol vectors of a plurality of spatial layers separated in 1403 by the reception weight matrix calculated in 1406, and performs spatial layer separation and phase correction of each spatial layer.

  The demodulation / decoding unit 1408 collects the data symbols obtained by spatial layer division in 1407 in units of codewords, obtains a log likelihood ratio for each bit, and performs Turbo decoding or Viterbi decoding. Of the decoded result, the data portion is stored in the reception data buffer 1409, and the control information is input to the base station control block 1411. The control information includes downlink first wireless channel quality and second wireless channel quality fed back by the terminal, downlink third wireless channel quality and reception success / failure information fed back by the relay device (1001 in FIG. 8). To the base station control block 1411 through this route. Note that the distinction between data and control information follows a wireless I / F protocol issued by a standards body to which the wireless communication system complies.

  The backhaul network I / F 1410 is an I / F for a backhaul network that is wired to a node higher than the base station, for example, an access gateway. The backhaul network I / F 1410 stores the transfer to the upper node of the reception data buffer 1409 and the data transferred from the upper node in the transmission data buffer 1412.

  Based on the communication quality estimation result obtained in 1405 and the feedback information from the relay device or terminal obtained in 1408, the base station control block 1411 performs uplink packet schedule, downlink packet schedule, that is, 601 in FIG. Resource allocation corresponding to 607 is performed. In the present embodiment, based on the reception result from the relay apparatus 103, it is determined whether or not the radio resource allocated to each relay apparatus needs to be released, and if released, resource allocation including the released resources is performed. That is, the base station control block 1411 reserves the transmission for the second wireless communication path corresponding to the communication that failed to be received according to the reception success / failure information of the third wireless communication path input via the demodulation decoder 1408. Release the radio resources that were being used. When there is no reception result or when the reception result indicates successful reception, radio resources other than the reserved radio resource are allocated to the first radio communication path and the third radio communication path. Proportional fairness is known as an algorithm for resource allocation, that is, packet scheduling.

  When proportional fairness is applied to the present embodiment, the communication quality of the second wireless communication path is set for a terminal via a relay device, and the communication quality of the first wireless communication path is set for a terminal that directly receives from a base station. Based on the instantaneous transmission rate. In the present embodiment, the radio resources of the second radio communication path are allocated in advance at the future time rather than the time at which the radio resources are allocated to the first radio communication path and the third radio communication path.

  Therefore, the base station control block 1411 predicts the fluctuation amount from the mobility of the terminal and the past communication result and adds it to the quality of the current second wireless communication channel, and at the current time, transmits the second wireless communication channel. Radio resources reserved for credit at a past time are not assigned to the first and third radio channels.

  Note that a terminal using an application that periodically generates data such as VoIP (Voice over IP) may be handled by SPS in LTE, for example. At this time, the route for transmitting data to the terminal may be determined by predicting the quality of the wireless communication path of the first route and the second route at a future time by the method of the previous period. The packet schedule result of the first wireless communication path or the third wireless communication path is input to the coded modulation processing unit 1413 as a downlink control signal. Further, the resource allocation information of the second wireless communication path is input from the base station control block 1411 to the transmission data buffer 1412 and is combined with the corresponding transmission data to generate transmission data of the third wireless communication path (602 in FIG. 5). Thus, the encoding modulation unit 1413 is instructed. Finally, the encoding modulation 1413 is instructed to fetch the data sequence from the transmission data buffer 1412 according to the downlink packet schedule result.

  The encoded modulation processing unit 1413 encodes and modulates the data sequence from the transmission data buffer 1412 and the control information sequence from the base station control block 1411, respectively. As encoding, for example, a convolutional encoder with an original encoding rate of 1/3 is used. The series of bit sequences output here is called a code word. In the modulation, the encoded output is mapped into a constellation of 2 bits bundled to QPSK, 4 bits bundled to 16QAM, and 6 bits bundled to 64QAM. The number of bits to be bundled depends on the downlink scheduling result obtained from 1411 and the protocol specification.

  The layer map 1414 is a process of mapping a modulation symbol sequence that forms a codeword output by encoding in 1413 to a plurality of spatial layers. Each modulation symbol is arranged in a specific OFDM symbol, subcarrier, and spatial layer. Since the placement rules are defined in the protocol, refer to a memory (for example, the storage device 1505 in FIG. 10) that stores all the placement positions in accordance with the rules, or by using a logic circuit in which the placement rules are algorithmized. Specify the location. The above arrangement is performed avoiding OFDM symbols, subcarriers, and spatial layers where reference signal symbols are stored. At this stage, the positions where reference signal symbols are stored are blank symbols. Blank symbols are symbols in which both the I component and the Q component are zero.

  The precoding processing unit 1415 is a process of handling 1414 layer map outputs for a plurality of spatial layers as vectors and multiplying the precoding matrix as a transmission weight matrix. The precoding processing unit 1415 performs this for all OFDM symbols and subcarriers. Even at this stage, the reference symbol is stored in a blank symbol.

  Reference numeral 1416 denotes a block that generates a downlink reference signal symbol sequence. As the reference signal symbol sequence, it is desirable to use an BPSK symbol sequence, a QPSK symbol sequence, or a Zadoff-Chu sequence generated based on an M sequence, PN sequence, or Walsh sequence having a low cross-correlation between reference signal symbol sequences. Since various series generation algorithms are widely known, the generation algorithm is realized by a logic circuit, or the output of all series generated in advance is stored in a memory (for example, the storage device 1505 in FIG. 10), This can be achieved by pulling a table.

  The reference symbol insertion processing unit 1417 inserts the reference signal symbol sequence generated in 1416 into a portion that is a blank symbol in the precoding output 1415. When this insertion processing is completed, IFFT processing is performed at 1418 for each OFDM symbol and output to the wireless front end 1401. The parts excluding the above 1401 and 1410 may be executed by a logic circuit, which is hardware included in the base station 101, or a processor such as a DSP or MPU.

  FIG. 10 shows another embodiment of the device configuration of the base station 101. The base station 101 includes a processor 1501, a data buffer 1502, and a memory 1503, which are connected by an internal bus 1504. Further, the network I / F includes a backhaul network I / F 1410 and a wireless front end 1401, and further includes a storage device 1505 for storing programs and tables.

  The processor 1501 executes a program stored in the storage device 1505. Further, the processor 1501 executes processing and the like corresponding to the base station control block of FIG. 9, refers to the table, and controls resource allocation and wireless communication.

  The data buffer 1502 corresponds to 1409 and 1412 in FIG. In the memory 1503, a program processed by the processor 1501 is expanded and data necessary for processing is held.

  The wireless front end unit 1401 is an interface that transmits and receives wireless signals to and from the relay device and the terminal device, as in FIG. The backhaul network I / F 1410 is the same interface as that shown in FIG. 9, and is an interface connected to a network connected between other base stations and a higher node of the base station.

  The storage device 1505 stores a channel quality estimation program 1506, a reference signal processing program 1507, a resource allocation program 1508, a resource reservation status management table 1509, a resource release program 1510, a relay device management table 1511, and a transfer time update program 1512. ing. In addition, the program corresponding to the process in the base station disclosed in the specification of the present application also stores those not shown.

  The channel quality estimation program 1506 corresponds to the communication quality estimation unit 1405 in FIG.

  The reference signal processing program 1507 corresponds to the processing performed by the reference symbol sequence generation unit 1416 and the reference symbol insertion unit 1417 in FIG.

  The resource allocation program 1508 corresponds to the packet schedule operation performed in the base station control block 1411 of FIG.

  The resource reservation status management table 1509 manages the positions of radio resources reserved for transmission on the second radio channel when the resource allocation program 1508 is operated. Specifically, for example, in the form shown in FIG. 21, the resource block 2401 for reserved relay apparatus transmission and the resource block for available base station transmission are managed by time and frequency resources, respectively.

  Prior to the operation of the resource allocation program 1508, the resource release program 1510 uses the radio resource reserved in the resource reservation status management table 1509 according to the information on the third wireless channel reception result of the relay device input in 1408 of FIG. Among them, the one corresponding to the communication of the third wireless communication path whose result is reception failure is released.

  FIG. 12 shows a configuration example of the relay device.

  Reference numeral 1701 denotes a radio front end on the base station side, and 1702 denotes a radio front end on the terminal side. The components are the same as 1401.

  The downlink baseband processing unit 1703 decodes the downlink baseband signal input from 1701 and inputs the decoded data to the relay device control block 1704. Further, it receives downlink resource allocation information and transmission data of the second wireless communication path from the relay device control block, encodes the transmission data, and outputs it to the terminal-side wireless front end 1702.

  The uplink baseband signal processing unit 1705 decodes the uplink baseband signal input from the terminal-side radio front end 1702 and inputs the decoded data to the relay device control block 1704. Further, it receives input of uplink resource allocation information and transmission data of the second wireless communication path from the relay device control block, encodes them, and outputs them to the base station side front end 1701.

  The relay apparatus control block 1704 performs processing corresponding to 605 and 606 in FIG. 5, update of the reception data buffer 1713 based on the reception signal input from the baseband processing units 1703 and 1705, and second wireless communication based on the reception data buffer. The resource allocation information and transmission data information of the path are input to the baseband processing units 1703 and 1705 and a transmission instruction is issued.

  FIG. 13 is a functional block configuration example regarding downlink communication in the relay apparatus.

  The downlink received baseband signal input from the base station side radio front end 1701 is subjected to FFT processing in 1706, and the data reference signal separation unit 1707 separates the data symbol and the reference signal symbol.

  With respect to the reference signal symbol separated by the data reference signal separation unit 1707, the propagation path response specifying unit 1708 performs response estimation of the downlink third wireless communication path. Similar to 1404 in the base station in FIG. 9, a known reference signal symbol is used on both the transmission and reception sides (base station and relay apparatus) for estimating the channel response. If the reference signal symbol does not change with time, a fixed and known reference signal symbol sequence is held in the memory. If the reference signal symbol changes with time, the rule of the reference signal symbol sequence shared between the transmission side and the reception side To generate a reference signal symbol sequence.

  The communication quality estimation unit 1709 estimates the communication quality of the downlink third wireless communication path based on the propagation path estimation result 1708. A specific communication quality estimation method is the same as 1405. The estimation result obtained here is input to the relay apparatus control block 1704.

  Weight calculation section 1710 and detection / layer separation section 1711 are the same as weight calculation section 1406 and detection / layer separation section 1407 of base station 101.

  The demodulator / decoder 1712 collects the data symbols obtained by spatial layer division in 1711 in units of codewords, obtains a log likelihood ratio for each bit, and performs Turbo decoding or Viterbi decoding. Among the decoded results, the relay data is stored in the downlink reception data buffer 1713 according to the format of FIG.

  The relay device control block 1704 instructs the uplink baseband processing unit to transmit the communication quality of the downlink third wireless communication channel estimated by the communication quality estimation unit 1709 as an uplink control signal as processing related to downlink communication. Process. Further, the relay device control block 1704 notifies the current time to the encoding modulation unit 1714. Also, the relay device control block 1704 notifies the reception data buffer 1713 of transmission time information on the second wireless communication path.

  The downlink reception data buffer 1713 manages the relay data information for downlink communication in the format shown in FIG. The downlink reception data buffer 1713 may be configured with a shift register. That is, the transmission time information input from the relay device control block 1704 is added to the head of the data input from the demodulation / decoding unit 1712 and input to the end of the shift register, and the encoded modulation unit 1714 is input. Outputs data from the beginning to the next transmission time information.

  The encoding modulation unit 1714 encodes and modulates the data sequence from the downlink reception data buffer 1713 according to control information unique to the data sequence. In this data series, the current time notified from the relay device control block 1704 is the transmission time. Note that a downlink data reception buffer 1713 constituted by a shift register or a memory may be used and its output may be targeted.

  The processing content of the layer map 1715 is the same as that of 1714, but further, modulation symbols are arranged on subcarriers and OFDM symbols indicated by the control information unique to the data series.

  The precoding unit 1716 handles a plurality of spatial layer outputs of the layer map output 1715 as a vector, and performs a process of multiplying the precoding matrix as a transmission weight matrix. The precoding unit 1716 performs this for the OFDM symbol and subcarrier to be transmitted.

  The reference symbol sequence generation unit 1717 is a block that generates a downlink reference signal symbol sequence. The reference signal symbol sequence generated in 1416 may be the same as or different from the reference signal symbol sequence, but when the reference signal symbols overlap the same OFDM symbol and subcarrier as the reference signal symbol sequence of the base station, the cross-correlation is as low as possible. Use the series. The reference signal symbol sequence generation method is the same as 1416.

  The reference symbol insertion unit 1718 performs processing to insert the reference signal symbol sequence generated by the reference symbol sequence generation unit 1717 into a portion that is a blank symbol in the precoding output of the precoding unit 1716. When this insertion processing is completed, IFFT processing is performed at 1719 for each OFDM symbol, and output to the terminal-side radio front end 1702.

  The functional blocks excluding the above 1701 and 1702 may be executed by a logic circuit, which is the hardware of the relay device, or a processor such as a DSP or MPU.

  FIG. 14 is a configuration example of uplink communication of the relay device.

  The uplink received baseband signal input from 1702 is subjected to FFT processing at 1720, and data symbols and reference signal symbols are separated at 1721.

  For the reference signal symbol separated in 1721, the response estimation of the uplink second wireless communication channel is performed in 1722. Similar to 1404, a known reference signal symbol is used on both the transmitting and receiving sides (terminal and relay device) for estimating the channel response. If the reference signal symbol does not change with time, a fixed and known reference signal symbol sequence is held in the memory. If the reference signal symbol changes with time, the rule of the reference signal symbol sequence shared between the transmission side and the reception side To generate a reference signal symbol sequence.

  1723 estimates the communication quality of the uplink second wireless communication channel based on the propagation channel estimation result of 1722. A specific communication quality estimation method is the same as 1405 of the base station 101. The estimation result obtained here is input to the relay apparatus control block 1704.

  1724 and 1725 are the same as 1406 and 1407, respectively.

  1726 collects the data symbols that have been spatially layer-divided in 1725 in units of codewords, obtains a log-likelihood ratio for each bit, and performs Turbo decoding or Viterbi decoding. Of the decoded result, the data portion is stored in the uplink reception data buffer 1727, and the control information is input to the relay device control block 1704. Note that the distinction between data and control information follows a wireless I / F protocol issued by a standards body to which the wireless communication system complies.

  The relay device control block 1704 performs uplink control on the communication quality of the uplink second wireless communication channel input from 1723 and the communication quality of the downlink third wireless communication channel estimated in 1709 as processing related to uplink communication. Processing to embed in the signal. 1728 encodes and modulates the data sequence from the uplink reception data buffer 1727 according to control information unique to the data sequence.

  The processing content of the layer map 1729 is the same as that of 1414, but modulation symbols are further arranged on subcarriers and OFDM symbols indicated by the control information unique to the data series.

  The precoding unit 1730 is a process of handling 1729 layer map outputs for a plurality of spatial layers as vectors and multiplying the precoding matrix as a transmission weight matrix. This is performed for all OFDM symbols and subcarriers.

  The reference symbol insertion unit 1731 is a block that generates an uplink reference signal symbol sequence. The reference signal symbol sequence generated in 2116 in FIG. 16 may be the same as or different from the reference signal symbol sequence. However, when the reference signal symbols overlap the same OFDM symbol and subcarrier as the reference signal symbol sequence of the terminal, the cross-correlation is as much as possible. Use a different low series. The reference signal symbol sequence generation method is the same as 1416. Reference numeral 1732 denotes processing for inserting the reference signal symbol sequence generated in 1731 into a portion that is a blank symbol in the precoding output of 1730. When this insertion processing is completed, IFFT processing is performed at 1733 for each OFDM symbol and output to the base station side radio front end 1701.

  The portions excluding the above 1701 and 1702 can be realized by a logic circuit, a processor such as a DSP or an MPU.

  FIG. 15 is a device configuration example of the relay device 103. The relay device 103 includes a processor 2001, a data buffer 2002, and a memory 2003, which are connected by an internal bus 2004. Further, the network I / F includes a base station radio front end 1701 and a terminal side radio front end 1702. Further, the relay apparatus 103 includes a storage device 2005 that stores programs and tables. The storage device 2005 stores a relay control program 2006, a channel quality estimation program 2007, and a reference signal processing program 2008. Note that programs and information corresponding to processing in the relay apparatus 103 disclosed in the present specification are also stored that are not shown.

  The communication channel quality estimation program 2007 corresponds to the communication quality estimation units 1709 and 1723 shown in FIGS.

  The reference signal processing program 2008 corresponds to the processing performed by the reference symbol sequence generation units 1717 and 1731 and the reference symbol insertion units 1718 and 1732 in FIGS.

  The processor 2001 executes a program stored in the storage device 2005. Further, the processor 2001 executes a program, executes processing corresponding to the relay device control block 1704, and the like, refers to a table, and controls wireless communication. The data buffer 2002 corresponds to 1713 in FIG. 13 and 1727 in FIG. In the memory 2003, a program processed by the processor 2001 is expanded and data necessary for the processing is held.

  The wireless front end units 1701 and 1702 are interfaces that transmit and receive wireless signals to and from the base station and terminal devices, as in FIG.

  FIG. 16 shows a functional block configuration example in the terminal 102 (same for 107 and 108). The wireless front end unit 2101 has components corresponding to the configuration of the wireless front end 2101.

  The downlink received baseband signal is subjected to FFT processing in 2102, and the data reference signal separation section 2103 separates the data symbol and the reference signal symbol.

  For the reference signal symbols separated by data reference signal separation section 2103, propagation path response estimation section 2104 performs response estimation of the downlink first wireless communication path and downlink second wireless communication path. For estimation of the propagation path response, known reference signal symbols are used on both the transmitting and receiving sides (base station and terminal, relay apparatus and terminal). If the reference signal symbol does not change with time, a fixed and known reference signal symbol sequence is held in the memory. If the reference signal symbol changes with time, the rule of the reference signal symbol sequence shared between the transmission side and the reception side To generate a reference signal symbol sequence.

  In addition, when a plurality of reference signal symbol sequences having low cross-correlation are multiplexed at the same time frequency, that is, reference signal symbol sequences having different base stations and relay devices, or different base station and relay devices are assigned the same time frequency. 11, the received reference signal symbol sequence is stored in the middle register 1604 so that the right side is the head, as shown in FIG. 11, and the complex conjugate of the known first reference signal symbol sequence is similarly stored. The upper right register 1601 stores the complex conjugate of the known second reference signal symbol sequence in the lower shift register 1605 so that the right side is first. In this state, as shown in the figure, adder 1603 and multiplier 1602 perform multiplication and addition, respectively, so that a propagation path response to the first reference signal symbol and a propagation path response to the second reference signal symbol are respectively obtained. Can be acquired. Here, the received reference signal symbol sequence is input from data reference signal separation section 2103, and the known first reference signal symbol and second reference signal symbol are stored in a memory (FIG. 17) for recording a fixed sequence used by 2104. The result generated from the memory 2203) or in accordance with the rule of the reference signal symbol sequence shared by the transmission side and the reception side in the propagation path response estimation unit 2104 is input.

  The communication quality estimation unit 2105 estimates the communication quality of each of the downlink first radio communication channel and the downlink second radio communication channel based on the channel estimation result of the channel response estimation unit 2104. The communication quality estimation method is the same as 1405. The uplink downlink first wireless channel quality and downlink second wireless channel quality estimated by the propagation path response estimation unit 2105 are input to the terminal control block 2111. 2106 and 2107 are the same as 1406 and 1407, respectively.

  In 2108, the data symbols divided in the spatial layer in 2107 are collected in units of codewords, a log likelihood ratio for each bit is obtained, and Turbo decoding or Viterbi decoding is performed. The decoded result is stored in the reception data buffer 2109, and the control information is input to the terminal control block 2111. As control information, uplink packet schedule information issued by the control block 1411 in the base station 101 is input to 2111. Note that the distinction between data and control information follows a wireless I / F protocol issued by a standards body to which the wireless communication system complies.

  The application 2110 is a processor for operating applications such as web and mail used in the terminal, and a user interface such as a screen and a keyboard. Data input from the application is stored in the transmission data buffer 2112 and transmitted according to the scheduling information generated by the base station 101.

  The terminal control block 2111 performs uplink control on the communication quality estimation result obtained in 2105, the driving of the encoding and modulation unit 2113 according to the uplink packet schedule information obtained in 2108, and the communication quality estimation result input from 2105. If the uplink data sequence generated by the application 2110 exists in the transmission data buffer 2112, the scheduling request for requesting the base station 101 to schedule the uplink packet is also encoded as control information. Input to the modulation unit 2113.

  The encoding modulation unit 2113 encodes and modulates the data sequence from the transmission data buffer 2112 and the control information sequence from the terminal control block 2111, respectively. The encoding method and the modulation method are the same as 1413. The layer map unit 2114 and precoding unit 2115 are the same as the layer map unit 1414 and precoding unit 1415 in FIG. 9, respectively.

  The reference symbol sequence generation unit 2116 is a block that generates an uplink reference signal symbol sequence. The reference signal symbol sequence generation method is the same as 1416.

  The reference symbol insertion unit 2117 is a process of inserting the reference signal symbol sequence generated in 2116 into a portion that is a blank symbol in the precoding output of the precoding unit 2115. When this insertion processing is completed, IFFT processing is performed at 2118 for each OFDM symbol and output to the wireless front end 2101. The portions excluding the above 2101 and 2110 can be realized by a logic circuit, a processor such as a DSP or an MPU.

  FIG. 17 is a device configuration example of the terminal 102 (the same applies to 107 and 108). The terminal 102 includes a processor 2201, a data buffer 2202, and a memory 2203, and each is connected via an internal bus 2204. Further, the terminal 102 includes a wireless front end 2101 as a network I / F. The terminal 102 also has a storage device 2205 that stores programs and tables.

  The storage device 2205 stores a channel quality estimation program 2206 and a reference signal processing program 2207. Further, the terminal 102 may store the data received from the base station 101 or the relay device in the storage device 2205 or the memory 2203. Note that the programs corresponding to the processing in the terminal 102 disclosed in the specification of the present application are also stored that are not shown.

  The communication channel quality estimation program 2206 corresponds to the communication quality estimation unit 2105 in FIG.

  The reference signal processing program 2207 corresponds to the processing performed by the reference symbol sequence generation unit 2116 and the reference symbol insertion unit 2117 in FIG.

  The processor 2201 executes a program stored in the storage device 2205. The processor 2201 executes a program, executes processing corresponding to the terminal control block 2111 and the like, and controls wireless communication.

  The data buffer 2202 corresponds to 2109 and 2112 in FIG. In the memory 2203, a program processed by the processor 2201 is expanded and data necessary for processing is held.

  The wireless front end unit 2101 is an interface that transmits and receives wireless signals to and from the base station 101 and the relay device, as in FIG.

  FIG. 18 shows a flowchart in the relay apparatus 103 as shown in the example of FIG. 13, FIG. 14 or FIG. The relay device 103 first receives the third wireless communication path control signal 303 for the third wireless communication path. The relay device 103 checks whether or not there is a resource allocation addressed to its own relay device (501), and if there is a resource allocation, specifies the specified frequency resource of the third channel data signal 304 transmitted at the corresponding time. The data is received after being demodulated and decoded by the above modulation method (502). As a result of step 502, the relay apparatus notifies the base station of a reception result indicating whether or not the data reception is successful (515).

  Thereafter, the relay device 103 stores the data stored in the format of FIG. 4 in the received data buffer (503). Next, the relay device compares the transmission time information in the reception data buffer with the current time (504), and if there is data to be transmitted at the current time, the transmission data (for example, 405) is associated with the corresponding MCS (for example, 404). The transmission data of the second wireless channel data signal 306 is generated by modulation and coding in (505), and is transmitted using the corresponding frequency resource (506). The second radio communication path control signal 305 may be transmitted by the relay station 103 itself or the base station 101 based on the stored resource allocation information 401 to 404.

  The terminals 102 and 107 can receive data from the second wireless communication path control signal 305 and the second wireless communication path data signal 306 in the same manner as in FIG. 2A when receiving data through the second wireless communication path. Note that the above-described H-ARQ is generally used in mobile communication. In asynchronous H-ARQ in which a retransmission packet is transmitted at an arbitrary timing, an operation involving the second radio channel control signal 305 is necessary even in retransmission, but synchronous H-ARQ in which the retransmission packet is always transmitted at a constant period. In this case, the second wireless communication path control signal 305 can be omitted in retransmission. At this time, since the relay apparatus holds the data bit sequence in the DF type, when a retransmission packet is generated by the relay apparatus alone, for the terminal subject to H-ARQ retransmission in the third wireless channel data signal 304 Information (for example, 401 to 405 in FIG. 4) may be omitted.

  The period of retransmission in synchronous H-ARQ can be specified using, for example, an RRC (Radio Resource Control) layer signal in addition to broadcasting using a Broadcast Channel in LTE. In addition, LTE has a mechanism called SPS (Semi-Persistent Scheduling) in which frequency resources are periodically allocated to a specific terminal. By applying this, a frequency resource for retransmission is preliminarily assigned to SPS when a new packet is transmitted. As described above, it is possible to make it unnecessary to acquire the resource allocation information via the third wireless communication channel in the retransmission as described above. Note that the step (503) of notifying the reception result for the relay device 103 to transfer data to the terminals 102 and 107 is unnecessary. However, by notifying the base station of the reception result, it is possible for the base station to reduce waste of radio resource allocation. The above is the description of FIG.

  FIG. 19 shows a data transmission schedule related to the second wireless communication path stored in the reception data buffer 1713 of the relay apparatus 103 in the processing 503 of FIG. This data transmission schedule is obtained by arranging the information in FIG. 4 based on the transmission time 402.

  FIG. 20 shows a flowchart regarding release of radio resources in the base station 101. This flowchart corresponds to the resource release program of FIG. 10 and is performed by the base station control block 1411. This flowchart corresponds to a part of the details of the resource allocation 607 in FIG. The base station 101 determines whether or not the reception result notified from the relay apparatus 103 in step 515 in FIG. 18 and 1101 in FIG. 5 has been received from the relay apparatus. With reference to this, it is determined whether or not the third wireless communication channel is received successfully (2301). When the reception failure notification 1102 is received, the base station 101 calculates the resources that the relay apparatus has allocated for transmitting the second wireless communication path.

  Specifically, first, the time at which the relay device was scheduled to transmit the second wireless communication path is calculated from the transfer time of the relay device and the current time (2302). Next, the reservation of the frequency resource performed for the relay device at the calculated time is canceled (2303). Resources reserved for the relay device can be managed using, for example, a table as shown in FIG. Reference numeral 2401 denotes a frequency resource that is reserved for transmission by the relay apparatus and cannot be used by the base station, and 2402 denotes a frequency resource that can be used for transmission by the base station. The resource reservation canceling operation 2303 means that the frequency resource set to 2401 is changed to 2402. After performing the above 2301-2303 for each relay apparatus, the base station 101 allocates its own resource for the remaining frequency resource as 2402 (2304). For example, at time t1, the base station 101 performs resource allocation for frequency resources excluding the frequency f4. With the above configuration, when communication on the third wireless communication path fails, the frequency resources allocated for transmission on the second wireless communication path are released, and the first wireless communication path or third wireless communication of the base station is released. Since it can be reused for route transmission, resource utilization efficiency can be improved. The above is the description of FIG.

  According to the first embodiment, the performance loss of the entire system due to the introduction of the relay device can be suppressed, and the performance gain can be increased. For example, the average frequency utilization efficiency of the cell can be increased.

  Further, in the above configuration, at each time, in order to ensure only the amount of radio resources predicted to be necessary in the second radio communication path, as in the case of securing radio resources fixedly as described above, It is possible to avoid a decrease in resource usage efficiency due to the difference between the secured frequency resource amount and the actual traffic amount. Moreover, it is set as the structure which avoids interference of a base station and a relay apparatus.

  On the other hand, the utilization efficiency of radio resources can be improved by reusing it for transmission of the base station. In other words, the relay device feeds back the success or failure of the reception of the third wireless communication channel, and the base station improves the resource utilization efficiency by releasing the frequency resource allocated to the relay device that failed to receive and reusing it for direct transmission To do. Here, in this embodiment, the transfer time of the relay device, that is, the time from when the relay device receives data on the third wireless communication path to when the data is transmitted on the second wireless communication channel can be arbitrarily set. Explained as a thing. The above is the first embodiment.

  Next, a second embodiment will be described. Unless otherwise noted, the description of the same parts as in the first embodiment is omitted. In the first embodiment, for example, the time used by the relay apparatus for decoding can be freely changed according to the data amount of the third wireless communication path. However, transmission time information is required for all the data of the second wireless communication channel, and the amount of overhead related to the transmission time determination processing in the base station 101, for example, in the processing 602 is large. In the second embodiment, the transfer time until the relay apparatus 103 transfers the data received via the third wireless communication path via the second wireless communication path is determined in advance between the base station and the relay apparatus. By setting, the amount of overhead is reduced.

  FIG. 22 shows a sequence of the wireless communication system in the second embodiment. From the base station side resource allocation 601 to the terminal side reception operation 610 in the communication via the relay apparatus is basically the same as in the first embodiment. The difference from the first embodiment is that the base station 101 determines a transfer time Δt from when the relay apparatus 103 receives data from the base station 101 (604) until it transmits data to the terminal (609). (710), and the process of notifying the determined Δt from the base station 101 to the relay apparatus 103 (720) is added. This Δt does not depend on the destination terminal, and is common to at least each relay apparatus, and the resource time regarding the third wireless communication path, which is considered in the resource allocation 601 and 607 of the base station, and in the future The interval until the time of transfer on the second wireless communication channel corresponding to the time is constant at least for each relay device, or the transfer time Δt can be set for each relay device, and the transfer time is updated. Is also possible. It should be noted that the timing of the transfer time setting operation 720 may be changed during operation using, for example, the RRC layer signal, even if it is initially set when the relay device (relay station) is introduced into the system. .

  In the above configuration, since the relay device can uniquely determine the transmission time of the received transmission data of the second wireless channel, the transmission time information is transmitted from the base station 101 to the relay device in the third wireless channel data signal 604. Sending is unnecessary, and the amount of overhead can be reduced.

  If the transfer time is uniform, the reception data buffer of the relay device can be configured by a shift register, so that the configuration can be simplified compared to the form of FIG. 19 corresponding to an arbitrary time.

  In the second embodiment, the case where the transfer time is uniformly set has been described as an example. In this modification, the base station 101 does not set the transfer time uniformly, but sets the transfer time according to the state of the propagation path of the third wireless communication path at 710 in FIG. This is because the resource utilization efficiency may not be improved depending on the transfer time value. The reason for this will be described with reference to FIG.

  FIG. 23 is a diagram illustrating the relationship between the transfer time in the second embodiment and the timing at which the resources of the third wireless communication path are released. In FIG. 23, as an example, the transfer time is 3 hours. In this case, for the data of the third wireless communication path transmitted at time 1, the reception success / failure 1001 is determined at time 4, and at the same time, the relay device starts transmission of the second wireless communication path. Therefore, the transmission time of the resource 803 has already passed when the resource release operation 1002 is performed, and the utilization efficiency cannot be improved by resource reuse as shown in FIG. However, the time at which the terminal can receive the data transmitted from the base station at time 1 through the second route is earlier than that in FIG. 8 (from time 6 to time 4), and the communication delay time via the relay device There is an effect that can be shortened.

  Hereinafter, in the present modification, details of the base station 101 determining the transfer time Δt will be described. FIG. 24 shows a flowchart in which the base station 101 determines the transfer time Δt for each relay device. The base station 101 performs transfer time update operations 1301 to 1304 for all the relay apparatuses that have established the third wireless communication path for each update cycle. Specifically, referring to the reception result 1001 of the third wireless communication path fed back by the relay apparatus, the PER of the third wireless communication path of the relay apparatus is updated (1301), and the obtained PER is determined in advance. It is compared with the determined threshold (1302). If PER is higher than the threshold, the resource use efficiency is set to the transfer time with priority (1303), and if PER is lower, the delay time is set to the transfer time with priority (1304). Here, each transfer time is, for example, a value giving priority to the delay time, which is the same as the time when the relay apparatus completes decoding of the reception data of the third wireless communication path (three times in the example of FIG. 8), and the resource utilization efficiency May be set so that the reception time of the information indicating the success or failure of the reception is earlier than the second wireless channel transmission time of the relay device (5 time in the example of FIG. 8).

  For example, in LTE, it is discussed to make the H-ARQ period of the third wireless communication channel the same as that of the first wireless communication channel. In this case, the value giving priority to the delay time may be 4 subframes, and the value giving priority to resource utilization efficiency may be 8 subframes. In WiMAX, when delay time is prioritized, the second wireless communication path is transmitted using the same frame as when the third wireless communication path is received. When resource utilization efficiency is prioritized, the second and subsequent frames are used. Two wireless communication channels may be transmitted. As an example, the former may be about 11 OFDM symbols, and the latter may be 55 OFDM symbols or more.

  In this modification, the base station control block 1411 in FIG. 9 measures the PER of the third wireless communication path by averaging the information on the success or failure of reception of the third wireless communication path for each relay apparatus, and according to the result, the relay apparatus Determine the transfer time for each. The base station control block 1411 further performs an operation of updating the transfer time for each relay device according to the PER of the third wireless communication path. The relay device management table 1511 manages the transfer time set for each relay device, the PER of the third wireless communication path, and the like.

FIG. 25 shows an example of the relay device management table 1511. The transfer time currently set for each relay device ID and the PER of the third wireless communication path are managed. The base station control block 1411 is updated according to the PER of the third wireless communication path stored in the relay device management table 1511.
Also, the transfer time update program 1512 in FIG. 10 is a program corresponding to FIG. 24 of this modification, and updates the transfer time for each relay device according to a certain standard.

  In the second embodiment, the relay apparatus control block 1704 in FIG. 13 holds the transfer time notified from the base station 101, and the transmission time of the second wireless communication path based on the held transfer time Δt information. Is input to the received data buffer 1713. When the transfer time information is input as control information from the demodulation / decoding unit 1712, the relay device control block 1704 performs processing to update the internally held transfer time to the received value.

  When the downlink reception data buffer 1713 in the modified example of the second embodiment is configured by a shift register and the transfer time Δt is changed, when the transfer time becomes long, 1704 is the number of transfer time information corresponding to the difference. May be temporarily input, and when the time becomes shorter, the input to 1713 may be stopped for the time corresponding to the difference 1704. The reception data buffer 1713 may be configured by a memory, record the last address of writing at each input time, and manage the transfer time. Also, information on the transfer time Δt is stored in the memory 2003 of the relay apparatus 103 in FIG.

  The relay control program 2006 in FIG. 15 corresponds to the relay device control block 1704 in FIGS. 13 and 14. In addition to the operation shown in FIG. 19, in the second embodiment, the transmission (transfer) time of the data received in the third wireless communication path is calculated based on the transfer time information stored in the memory 2003, and received. Input to the data buffer 1713. When the transfer time can be changed during operation, the transfer time is updated by detecting the control signal of the RRC level from 1712, for example. On the other hand, a long transfer time that improves the utilization efficiency by reusing resources and a short transfer time that shortens the delay time are prepared, and the use of values suitable for each relay device can be expected to achieve both effects. For example, based on the PER (Packet Error Rate) of the third wireless communication path, the PER is less than the threshold value, that is, when the environment of the third wireless communication path is good, priority is given to the delay time, and when the PER is more than the threshold value, the use efficiency is improved Priority should be given. With the above operation, both resource utilization efficiency and delay time are achieved.

  As described above, in the modification of the second embodiment, the case where the base station performs the PER measurement and the determination of the transfer time and notifies the relay apparatus is described. However, the relay apparatus may measure the PER and feed back. Further, the threshold value and the corresponding transfer time related to the PER may be shared between the base station and the relay device, the relay device may perform PER measurement and transfer time determination, and the determined transfer time may be fed back to the base station. . At this time, the feedback may be handled as desired by the relay apparatus, and finally the base station may determine.

  In the various embodiments described above, the performance loss of the entire system due to the introduction of the relay device can be suppressed, and the performance gain can be increased. For example, the average frequency utilization efficiency of the cell can be increased.

101 Base station 102 First terminal 103 First relay device 104 First wireless communication path 105 between base station and terminal Second wireless communication path 106 between relay apparatus and terminal Third wireless communication path 107 between base station and relay apparatus Second terminal 108 Third terminal 201 Wireless communication resource 202 assigned to the first wireless communication path Wireless communication resource 203 assigned to the second wireless communication path 203 Wireless communication resource 301 assigned to the third wireless communication path First wireless Communication channel control signal 302 First wireless communication channel data signal 303 Third wireless communication channel control signal 304 Third wireless communication channel data signal 306 Second wireless communication channel control signal 307 corresponding to transmission of the relay device Second wireless channel data signal 401 ID of destination terminal of first second wireless channel transmission data
402 Transmission time 403 of first second wireless communication path transmission data 403 Frequency resource used for first second wireless communication path transmission data 404 Encoding and modulation method 405 of first second wireless communication path transmission data First Second wireless channel transmission data

Claims (26)

A wireless communication system,
A base station,
A first terminal communicating with the base station via a first wireless communication path;
A relay device that communicates with a second terminal via a second wireless communication path and communicates with the base station via a third communication path;
The base station has a radio resource corresponding to a first time with respect to the first radio communication path and a second time after the first time with respect to the second radio communication path. Assigning a radio resource corresponding to the first time and a radio resource corresponding to the first time to the third communication path,
A radio resource allocation unit that allocates a radio resource corresponding to the second time to the first radio communication path based on a radio resource allocated to the second radio communication path;
The third with the communication path allocated radio resource, information about the radio resource corresponding to the second of said second time allocated to the wireless communication channel corresponding to the first time A relay transmission unit for transmitting to the relay device;
A first terminal transmission unit for transmitting a signal corresponding to the first terminal according to a radio resource corresponding to the first time,
The relay device includes a second terminal transmission unit that transmits a signal corresponding to a second terminal based on the information on the allocated radio resource.
A wireless communication system. The wireless communication system according to claim 1,
The relay device communicates with the plurality of second terminals via second wireless communication,
The wireless communication system, wherein the information related to the wireless resource includes information corresponding to a plurality of the second terminals. The wireless communication system according to claim 1,
The radio resource allocation unit of the base station sets the interval between the first time and the second time in common for a plurality of relay devices, and the time interval set for the plurality of relay devices A wireless communication system, characterized by: The wireless communication system according to claim 1,
The radio resource allocation unit of the base station sets a time interval between the first time and the second time by setting different time intervals for a plurality of relay devices, and sets the time interval via the relay transmission unit A wireless communication system, wherein the transmitted time interval is transmitted to the relay device. A wireless communication system according to claim 4,
The wireless communication system, wherein the time interval is set based on a quality of the third communication path. The wireless communication system according to claim 1,
The wireless communication system, further comprising: a reception success / failure determination unit that determines success / failure of reception of information related to the wireless resource from the base station and notifies the determination result to the base station. The wireless communication system according to claim 6 ,
The radio resource allocation unit of the base station receives the determination result, and allocates a radio resource corresponding to the second time to the first radio communication path based on the determination result. A wireless communication system. The wireless communication system according to claim 6,
When the determination result indicates reception failure, the radio resource allocation unit of the base station releases the radio resource corresponding to the second time allocated to the second radio communication path. A wireless communication system characterized by that. The wireless communication system according to claim 7,
When the determination result indicating that reception is not received within a predetermined time after the radio resource corresponding to the first time is allocated, the radio resource allocation unit of the base station A radio communication system, wherein a radio resource corresponding to the second time allocated to a radio communication path is released. The wireless communication system according to claim 1,
The information on the radio resource includes allocation information for specifying the allocated radio resource, and data to be transmitted using the radio resource,
The radio resource allocation unit of the base station device is
Using the radio resource at the first time, which is different from the radio resource at the first time allocated to the first radio communication path, the information about the radio resource via the relay transmission unit A wireless communication system characterized by transmitting. The wireless communication system according to claim 9, wherein
A radio communication system, wherein radio resources allocated to the first radio communication path, the second radio communication path, and the third communication path are different frequency resources at the same time. A base station device,
A first communication path that communicates with the first terminal, a second terminal and a second radio interface connected with a third communication channel that communicates with the relay device, the via the communication path communicates When,
A control unit connected to the wireless interface,
Wherein the control unit includes a radio resource in the first time by to said first communication channel, and radio resources in the second second time Ru Oh later than the first time to the communication path , Assigning radio resources at the first time to the third communication path,
Sending information on the radio resource at the second time allocated to the second communication path to the relay device using the radio resource at the first time via the radio interface,
A base station apparatus, wherein a radio resource at the second time is further allocated to the first communication path. The base station apparatus according to claim 12, wherein
The controller is
Receiving success / failure information regarding success / failure of reception of information on the radio resource in the relay device from the relay device via the wireless interface;
A base station apparatus, wherein a radio resource at the second time is allocated to the first communication path based on the success / failure information. The base station apparatus according to claim 13, wherein
The controller is
When the success / failure information indicates NO,
Releasing radio resources in said second through said second time allocated for signal path, the base station apparatus, characterized in that. The base station apparatus according to claim 12, wherein
The base station apparatus, wherein the control unit allocates a radio resource different from a radio resource already allocated at the second time to the first communication path at the second time. The base station apparatus according to claim 12 , wherein
The control unit uses the radio resource at the first time, which is different from the radio resource at the first time, assigned to the first communication path via the radio interface. A base station apparatus that transmits information about resources. The base station apparatus according to claim 12, wherein
The base station apparatus characterized in that the information on the radio resource includes assignment information for specifying the assigned radio resource and data to be transmitted using the radio resource. The base station apparatus according to claim 12, wherein
The controller is
Based on the quality of the third communication path, in the relay device, a transfer time of data addressed to the second terminal from the base station device is set, and the set transfer time is set to one or a plurality of the relay devices. Transmitting via the wireless interface to the base station apparatus. The base station apparatus according to claim 18, wherein
When the quality of the third communication channel is in the first state, the control unit sets the transfer time at a first time interval,
If the quality of the third communication channel is a second state worse than the first state, the transfer time is set at a second time interval longer than the first time interval,
A base station apparatus. The base station apparatus according to claim 18, wherein
The controller is
Receiving success / failure information regarding success / failure of reception of information on the radio resource in the relay device from the relay device via the wireless interface;
If the quality of the third communication channel is better than a predetermined state, a transfer time longer than the time interval from the transmission of information on the radio resource to the reception time at which the base station apparatus receives the success / failure information is set. Set,
If it is worse than the predetermined state, set a transfer time shorter than the time interval from the transmission of information on the radio resource to the reception time at which the base station apparatus receives the success / failure information,
A base station apparatus. The base station apparatus according to claim 16, wherein
The base station apparatus characterized in that the radio resources allocated to the first communication path, the second communication path, and the third communication path are frequency resources at the same time. A backhaul link for communication between the base station and the relay station, a direct link for communication between the base station and the first terminal, and a communication between the relay station and the second terminal. A wireless communication method communicated with an access link of
The base station determines a first radio resource to be allocated to the backhaul link at a first time and a second radio resource to be allocated to the access link at a second time after the first time And
In the base station, the information on the second radio resource is transmitted to the relay station using the third radio resource at the first time allocated to the backhaul link,
In the relay station, notify the base station of the success or failure of receiving information on the second radio resource,
A radio communication method , wherein the base station allocates radio resources to the direct link at the second time based on the success or failure . The wireless communication method according to claim 22, wherein
If the reception was unsuccessful,
The radio communication method, wherein the base station releases the second radio resource and allocates a radio resource to the direct link at the second time. The wireless communication method according to claim 22, wherein
The radio communication method according to claim 1, wherein the radio resource at the second time is a resource for performing radio communication corresponding to a frequency. The wireless communication method according to claim 22, wherein
The wireless communication method according to claim 1, wherein the first wireless resource and the third wireless resource are resources corresponding to different frequencies at the first time. The wireless communication method according to claim 22, wherein
Further, the base station notifies the relay station of the interval between the first time and the second time.
A wireless communication method.

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