Communication system, communication control method, and communication control device

Abstract

To reduce power consumption of relay stations that perform non-reproduction relaying.SOLUTION: A communication control device performs processing to select a relay station to be used for relaying uplink communication from a terminal station to a base station from among a plurality of relay stations included in a communication system. The communication control device selects a relay station to be used for relaying from remaining relay stations that are relay stations obtained by excluding relay stations whose power consumption is to be considered from relay stations that can be used for relaying among the plurality of relay stations.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a communication system, a communication method, and a communication control device. [Background technology]

[0002] In 3GPP (registered trademark), regenerative relaying is a relaying technique aimed at expanding the coverage area of ​​a cell (for example, Non-Patent Document 1). In addition, non-regenerative relaying, which does not perform demodulation or decoding at the relay station, is a relaying technique with low delay (for example, Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP (registered trademark) TS 38.174 V17.0.0 (2022-03) [Non-patent document 2] 3GPP (registered trademark) TS 38.106 V17.0.0 (2022-03) Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a communication system, a communication method, and a communication control device that can reduce the amount of power consumption of a relay station that performs non-regenerative relay. [Means for solving the problem]

[0005] One aspect of the present disclosure includes a communication control device that performs a process of selecting a relay station to be used for relaying uplink communication from a terminal station to a base station from among a plurality of relay stations, and the communication control device selects a relay station to be used for the relay from one or more relay stations available for the relay among the plurality of relay stations, excluding relay stations that take power consumption into consideration. It is a communication system.

[0006] Furthermore, one aspect of the present disclosure is a communication control method that includes a communication control device that performs a process of selecting a relay station to be used to relay uplink communication from a terminal station to a base station from among a plurality of relay stations, and that selects a relay station to be used for the relay from one or more relay stations available for the relay among the plurality of relay stations, excluding relay stations that take power consumption into consideration.

[0007] One aspect of the present disclosure is a communication control device that performs a process of selecting a relay station from a plurality of relay stations to be used to relay uplink communication from a terminal station to a base station, and selects a relay station to be used for the relay from one or more relay stations available for the relay among the plurality of relay stations, excluding relay stations that take power consumption into consideration.

[0008] The present disclosure may include the base station, relay station, and terminal station that constitute the above-mentioned communication system, a program, a storage medium capable of temporarily storing the program, and the like. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to reduce the amount of power consumption of a relay station that performs non-regenerative relay. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a first configuration example of a communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a second configuration example of the communication system according to the embodiment. [Figure 3] FIG. 3 is a diagram illustrating an outline of processing in the communication system. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of the control device. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of a relay station. [Figure 6] FIG. 6 is a diagram illustrating an example of the configuration of a relay path. [Figure 7]FIG. 7 is a flowchart showing an example of processing in the base station and the relay station. [Figure 8] FIG. 8 is a flowchart showing an example of a relay station selection process. [Figure 9] FIG. 9 is a flowchart showing an example of a relay station selection process. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a communication system according to an embodiment will be described with reference to the drawings. The configurations of the following embodiments are examples, and the present disclosure is not limited to the configurations of the embodiments. Note that, in the embodiments, a 5G (fifth generation mobile communication system) communication system is exemplified, but the configurations of the transmitting station, relay station, and receiving station according to the present disclosure can be applied to communication systems other than 5G.

[0012] Fig. 1 is a diagram showing a first configuration example of a communication system. In Fig. 1, a communication system 100A according to the first configuration example includes a control device 1, a base station 2, a plurality of relay stations 3, and a plurality of terminal stations 4. There may be two or more base stations 2, and the number of relay stations 3 and terminal stations 4 may be any appropriate number greater than or equal to two.

[0013] The control device 1 is a device on a network (e.g., a core network (5GC)) to which the base stations 2 are connected. However, it is also possible to consider that the control device 1 is the core network itself or a system included in the core network. The core network includes, for example, an optical fiber network. The control device 1 controls the base stations 2, relay stations 3, and terminal stations 4, and provides communication services to the terminal stations 4.

[0014] The base station 2 provides a wireless access network to the terminal station 4. An area where wireless communication is possible in the wireless access network is also called a cell. The base station 2 has one or more antennas (one antenna is illustrated in FIG. 1), a radio 21 corresponding to the antenna, and a control circuit 22. The control circuit 22 has, for example, a processor and a memory. The processor controls communication with the control device 1 (base station 2) and wireless communication with the relay station 3 and the terminal station 4 by executing a computer program stored in the memory.

[0015] The relay station 3 relays (performs non-regenerative relay) wireless communications between the base station 2 and the terminal station 4 in both the uplink and downlink directions. The relay station 3 may be, for example, a small base station, a mobile base station, an in-vehicle device, or a smartphone. The relay station 3 can be selected as a relay station by the control device 1 from among devices configured to perform non-regenerative relay. When a connection request is received from the terminal station 4, the control device 1 can select one or more relay stations 3 located within the range of the cell provided by the base station 2 and transmit an instruction to each relay station 3 to perform non-regenerative relay of the wireless communications. The relay station 3 that receives the instruction operates as the relay station 3 selected by the control device 1.

[0016] Like the base station 2, the relay station 3 has one or more antennas 33 (FIG. 1 illustrates a plurality of antennas 33), a radio device 31 corresponding to the antennas 33, and a control circuit (controller) 32. Note that, since the control circuit 32 of the relay station 3 receives information related to control, the relay station 3 may have an antenna 34 independent of the relay line (antenna 33).

[0017] The terminal station 4 is, for example, a mobile station such as a smartphone, a tablet terminal, a wearable terminal, or an in-vehicle data communication device. However, the present invention is not limited to this, and the terminal station 4 may also be a stationary terminal device. For example, the terminal device connects to a wireless access network within the range of a cell provided by the base station 2.

[0018] The terminal station 4 includes one or more antennas 43 (one antenna 43 is shown in FIG. 1) used to receive radio signals, a radio device 41 connected to the antenna, and a control circuit 42. For example, a mobile station within a cell requests a base station 2 to connect to a wireless access network, and when the mobile station is connected, the mobile station operates as a terminal station 4. The mobile station within the cell may request a connection to the wireless access network directly from the base station 2. Alternatively, the mobile station within the cell may request a connection to the wireless access network from the base station 2 via a device operating as a relay station 3 within the cell. The terminal station 4 can be said to be a station that can communicate with the base station 2 via one or more relay stations 3 or without via any of the one or more relay stations 3.

[0019] Fig. 2 is a diagram showing a second configuration example of a communication system. A communication system 100B according to the second configuration example shown in Fig. 2 may be applied as the communication system. The communication system 100B differs from the communication system 100A of Fig. 1 in the following respects. That is, the base station 2 in the communication system 100B includes a control circuit 2A and one or more wireless stations 2B.

[0020] The control circuit 2A corresponds to the control circuit 22 in the communication system 100 and controls the operation of each wireless station 2B. The wireless station 2B has a wireless device 21 corresponding to an antenna 23. The control circuit 2A and the wireless device 21 of the wireless station 2B are connected, for example, by optical fiber or a wireless network. The topology of the optical fiber connecting the control circuit 2A and each wireless station 2B is not limited to a specific topology. For example, the optical fiber topology may be a one-to-one connection between nodes, a network that branches with increasing distance from the control circuit 2A, a star network, a ring network, or the like. Furthermore, when the control circuit 2A and the wireless device 21B of the wireless station 2B are connected by a wireless network, the standard and protocol of the wireless network employed are not limited to a specific one.

[0021] The control circuit 2A has a processor and a memory, similar to the control circuit 22 in Fig. 1. The processor controls communication with the control device 1 and wireless communication with the relay station 3 and terminal station 4 by executing a computer program stored in the memory. That is, the control circuit 2A controls wireless communication with the relay station 3 and terminal station 4 via the radio 21B of the wireless station 2B. The configurations of the relay station 3 and terminal station 4 are the same as those of the communication system 100A, so repeated explanations will be omitted. Hereinafter, when there is no need to distinguish between the communication system 100A and the communication system 100B, they will be referred to as the communication system 100.

[0022] The communication system 100 is a 5G network, and the following configuration is adopted as a premise. The basic communication unit is a 10 millisecond "frame", which is divided into 1 millisecond long "subframes", for example, and the subframes are further divided into 0.5 millisecond "slots", and the slots are divided into 14 "symbol" units. A cyclic prefix (CP) is inserted between each symbol. For example, 1 slot = 14 symbols x 12 (180 kHz) subcarriers are defined as a resource block (RB). A resource block is the communication This is the basic unit. In 5G networks, orthogonal frequency-division multiplexing (OFDM) is used as the digital modulation method for baseband signals. Data baseband signals are digitally modulated onto subcarriers that form resource blocks.

[0023] The resource blocks used by the terminal station 4 for communication on the uplink and downlink are allocated to the terminal station 4A and the terminal station 4A by the control device 1 or the control circuit 22 (control circuit 2A) of the base station 2. The resource blocks used for non-regenerative relay are also allocated to the relay station 3 and the terminal station 4 by the control device 1 or the control circuit 22 (control circuit 2A) of the base station 2.

[0024] In the communication system 100, communication is performed by time division multiplexing, and the same frequency channel is used in the uplink and downlink. In addition, between the base station 2, the relay station 3, and the terminal station 4, the start timing of each slot constituting a wireless frame is are synchronized.

[0025] In communication system 100, a block transmission method with a cyclic prefix (CP), such as CP-OFDM (Cyclic Prefix - Orthogonal Frequency Division Multiplexing), is adopted as a wireless modulation method. In this embodiment, a case where CP-OFDM is applied will be described, but a block transmission method with a CP other than CP-OFDM may also be used. In addition, relay station 3 shares resource block information used in the uplink and downlink by terminal stations 4 that are the targets of relaying.

[0026] The uplink is a link in the direction from the terminal station 4 to the base station 2. The downlink is a link in the direction from the base station 2 to the terminal station 4. The following explanation will exemplify a case where non-regenerative relaying is performed on the downlink. That is, the base station 2 and the wireless station 2B each correspond to a "transmitting station", and the terminal station 4 corresponds to a "receiving station". The control device 1, the control circuit 22 of the base station 2, and the control circuit 2A are each an example of an "information processing device" or a "communication control device". The non-regenerative relaying performed by the relay station 3 in the embodiment may also be applied to uplink communications. In the following explanation, a communication system 100A will be explained as an example of a communication system.

[0027] Fig. 3 is a diagram illustrating an outline of processing in a communication system. In Fig. 3, terminal stations 4a to 4c are examples of multiple terminal stations 4. Relay stations 3a and 3b are examples of multiple relay stations 3. In uplink communication, each of the terminal stations 4a to 4c can wirelessly transmit signals s1 to s3 using different frequencies to the uplink so that the signals do not interfere with each other. Each of the relay stations 3a and 3b can receive signals s1, s2, and s3 from the terminal stations 4a to 4c, and transmit a signal in which these signals s1, s2, and s3 are superimposed to the uplink (to the base station 2).

[0028] Here, relay station 3a is powered by commercial power and has no limit on its operating time. In contrast, relay station 3b is powered by battery 5 and has a limit on its operating time. If such relay station 3b always performs non-regenerative relay, the battery 5 will consume a lot of power, which may result in a short operating time. In this embodiment, a communication system 100 that can solve such a problem will be described.

[0029] In the communication system 100 according to the embodiment, when selecting a relay station 3, the ability to simultaneously relay signals from multiple terminal stations, which is a feature of non-regenerative relay, is taken into consideration, and the use of relay stations 3 that require consideration of power consumption, such as battery operation, is avoided as much as possible. Furthermore, in the communication system 100, the amplification factor (gain: ratio of received signal power to transmitted signal power) of the relay signal at the relay station 3 is also reduced as much as possible, thereby reducing power consumption. This makes it possible to provide an expanded coverage of low-latency communication, including relay stations 3b that cannot secure a sufficient power source, such as battery operation.

[0030] FIG. 4 is a diagram illustrating an example of the hardware configuration of the control device 1. The control device 1 has a CPU 11, a main memory device 12, and external devices, and executes communication processing and information processing by computer programs. The CPU 11 is also called a processor. The CPU 11 is not limited to a single processor, and may have a multi-processor configuration. The CPU 11 may also include a graphics processing unit (GPU), a digital signal processor (DSP), etc. The CPU 11 may also include a field programmable gate array (FPGA), etc. The external device may be one that cooperates with a hardware circuit of the above. Examples of the external device include an external storage device 13, an output device 14, an operation device 15, and a communication device 16.

[0031] The CPU 11 executes a computer program that has been loaded in an executable manner into the main storage device 12, and provides processing for the control device 1. The main storage device 12 stores the computer program executed by the CPU 11. The main memory device 12 stores the data to be processed by the CPU 11, the program, etc. The main memory device 12 is a dynamic random access memory (DRAM), a static random access memory (SRAM), a read only memory (ROM), etc. Furthermore, the external memory device 13 is, for example, the main memory device 1 The external storage device 13 is used as a storage area supporting the CPU 11 and stores computer programs executed by the CPU 11, data processed by the CPU 11, etc. The external storage device 13 is a hard disk drive, a solid state drive (SSD), etc. Furthermore, the control device 1 may include a removable storage medium. A drive of the body may be connected to the removable storage medium, such as a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), a flash memory card, etc.

[0032] The output device 14 is, for example, a display device such as a liquid crystal display or an electroluminescence panel. However, the output device 14 may also include a speaker or other device for outputting sound. The operation device 15 is, for example, a touch panel with a touch sensor superimposed on a display. The communication device 16 communicates with the base station 2 and an external network such as the Internet via, for example, optical fiber. The communication device 16 is, for example, a gateway connected to the base station 2 and a gateway that communicates with an external network such as the Internet. The communication device 16 may be a single device or a combination of multiple devices. The hardware configuration of the control device 1 is not limited to that shown in FIG. 5.

[0033] In addition, the control circuit 22 of the base station 2, the control circuit 2A, the control circuit 32 of the relay station 3, and the control circuit 42 of the terminal station 4 described above are configured as devices equipped with the CPU 11, the main memory device 12, and the external memory device 13 described above, and the CPU 11 executes a program to perform predetermined processing.

[0034] Fig. 5 is a diagram showing an example of the configuration of a relay station 3. In Fig. 6, the relay station 3 includes an antenna 33, a radio device 31 corresponding to the antenna 33, and a control circuit (controller) 32. Although Fig. 6 shows an example of a relay station 3 having one antenna 33, the relay station 3 may have two or more antennas. In this case, a radio device 31 is provided for each antenna 33.

[0035] The radio device 31 has the same configuration. That is, the radio device 31 has a transmitter 311, a receiver 312, and a baseband circuit 313. The transmitter 311 and the receiver 312 are connected to the antenna 33 via a circulator 314. That is, the transmitter 311, the receiver 312, and the antenna 33 are connected to three ports of the circulator 314. A signal received by the antenna 33 is input to the first port of the circulator 314 and transmitted to the receiver 312 from the second port. A transmission signal from the transmitter 311 is input to, for example, the third port of the circulator 314 and transmitted to the antenna 33 from the first port.

[0036] Here, the power difference between the transmitted signal and the received signal is, for example, about 100 dB. On the other hand, the isolation of the circulator 314 is about 30 dB, and a portion of the transmitted signal interferes with the received signal. The interference between a portion of the transmitted signal and the received signal in the radio device 31 is called self-interference. Self-interference can be suppressed by setting predetermined weights to the radio frequency (RF) analog filter in the receiver 312 and the FIR (Finite Impulse Response) filter included in the baseband circuit 313.

[0037] The receiver 312 receives a received signal (for example, a radio signal (first radio signal) from the base station 2) from the antenna 33 via the circulator 314. The receiver 312 has a quadrature detection circuit and an analog-to-digital (AD) converter. The receiver 312 down-converts the received signal by quadrature detection, and further converts it into digital data by the AD converter to output the base signal. The receiver 312 inputs the obtained baseband signal to the baseband circuit 313.

[0038] The baseband circuit 313 includes an FIR filter. By setting a weight for the FIR filter, the FIR filter operates as a self-interference cancellation circuit that suppresses or cancels a transmission signal that mixes with the baseband signal input from the receiver 312 and causes self-interference. The output signal from the baseband circuit 313 is input to the transmitter 311, converted into a radio signal addressed to the destination, and emitted from the antenna 33. The destination is the base station 2 for the uplink, and the terminal station 4 for the downlink.

[0039] Fig. 6 is a diagram showing an example of the configuration of a relay path in communication system 100. In Fig. 6, there are a plurality of terminal stations k (k = 1 to 4) as the plurality of terminal stations 4. There are also a plurality of relay stations j (j = 1 to 4) as candidates for relay station 3 that relays signals from the plurality of terminal stations k to base station 2. The number of terminal stations 4 can be selected to be one or more. The number of candidates for relay station 3 can be selected to be two or more.

[0040] The propagation path (channel matrix) of a signal transmitted from terminal station 4 to relay station 3 is expressed as H_(j,k)^UE→R. Also, the propagation path (channel matrix) of a signal transmitted from relay station 3 to base station 2 is expressed as H_(j)^R→BS. Base station 2 (or control device 1) selects one or more relay stations 3 that will receive a signal from terminal station k from among the relay station 3 candidates. The relay station 3 is selected taking into consideration the power source of the relay station (whether it is battery-powered or not), etc.

[0041] 7 is a flowchart showing an example of processing by the base station 2 and relay station 3 (relay station j=1 to n (n is a natural number equal to or greater than 2)). The processing by the base station 2 shown in FIG.

[0042] The base station 2 instructs each of the candidate relay stations j to measure the received signal power (step S01). The relay station j that has received the instruction receives a reference signal such as a control channel transmitted from the terminal station k to the base station 2 based on the instruction from the base station 2, and measures the received signal power p_(j,k)^RX (step S001). The relay station j also acquires the remaining self-interference power I_(j) and the noise floor Nj of the relay station j. The self-interference power and the noise floor are acquired in advance. It may be done.

[0043] The relay station j transmits a notification (message) including measurement results (measurement values) of the received signal power, self-interference power, and noise floor to the base station 2 (step S002). At this time, if the relay station j is battery-powered, for example, and there is a request to reduce power consumption (a request for consideration of power consumption), the relay station j can include the request in the notification. Furthermore, in addition to or instead of the request, the relay station j may include information indicating the remaining battery capacity of the relay station j in the notification.

[0044] The relay station j uses the transmission signal of the notification to the base station 2 to set the filter (FIR filter) in the self-interference suppression process (step S003).

[0045] Base station 2 receives the notification from relay station j (step S02). Base station 2 also measures the path loss L_(j^R→BS) between the base station and the relay station using the reference signal used in the notification from relay station j (step S03).

[0046] From the measurement values ​​reported by base station 2 and relay station j and the path loss between the base station and relay station, the SINR (Signal-to-Noise Ratio) at the base station is calculated as Γ_(j,k)^R→BS (equation Based on (1), the desired gain G_(j,k)^R required at relay station j is calculated (Equation 2). The desired gain G_(j,k)^R is calculated based on the MCS (Modulation Scheme) used in the communication as shown in Equation 1. The SINR between the terminal station and the relay station is calculated using Γ_(jk)^REQ, which is the desired SINR specified in the IEEE 802.11b / g and Coding Scheme, and the desired margin M (usually 2 to 4). Base station 2 also uses Equation 3 to calculate Γ_(jk)^UE→R, which is the SINR between the terminal station and the relay station.

number

number

number

[0047] The base station 2 selects a relay station to be used for uplink communication (step S05). Fig. 8 is a flowchart showing an example (first example) of the process of selecting a relay station j.

[0048] In step S101, the base station 2 sets the value of index k' to k'=1 (identifying the terminal station k having the index of k'=1). The index k' is an index number assigned to each terminal station k when the terminal stations k are arranged in descending order of the desired SINR.

[0049] In step S102, the base station 2 determines whether there are multiple relay stations available to the terminal station k'. If it is determined that there are multiple relay stations, the process proceeds to step S103; if not, the process proceeds to step S109. In this embodiment, as an example, an "available relay station" is a relay station j for which the SINR between the terminal station and the relay station = Γ_(j,k)^UE→R is equal to or greater than the desired SINR = MΓ_(k)^REQ with a margin added, and the desired gain G_(j,k)^R is equal to or less than the maximum gain applicable to the relay station j.

[0050] In step S103, the base station 2 determines whether there is a relay station j among the available relay stations that should be considered in terms of power consumption. If it is determined in step S103 that there is a relay station j that should be considered, the process proceeds to step S104; otherwise, the process proceeds to step S105. Relay stations j that should be considered in terms of power consumption are, for example, the following relay stations. Relay station receiving a request for consideration of power consumption Relay station j whose notified remaining battery power falls below the threshold value of base station 2

[0051] In step S104, the base station 2 deletes (excludes) the relay station j that has been determined as the relay station j to be considered from the candidates for use.

[0052] In step S105, the base station 2 is already used by another terminal station k among the candidates. It is determined whether or not a relay station j exists. This determination can be made using information (stored in the main storage device 12 or the external storage device 13) indicating the allocation status of terminal station k to each relay station j. If it is determined that a relay station j that satisfies the condition (being used by another terminal station k) exists, the process proceeds to step S106; if not, the process proceeds to step S107.

[0053] In step S106, the base station 2 adds the relay station j selected by the rule A as a relay station to be used. Rule A is as follows. (1) If there is only one relay station j that satisfies the condition in step S105, that relay station j is selected. (2) If there are multiple relay stations j that satisfy the condition of step S105, the relay station j whose desired gain is greater than and closest to G_(j,k')^R is selected. That is, the value of the desired gain G_(j,k)^R (corresponding to the second gain) calculated for each relay station j currently being used to relay a terminal station k other than k' is compared with the value of G_(j,k')^R (corresponding to the first gain), and the relay station j having the desired gain G_(j,k)^R that is greater than G_(j,k')^R and closest to G_(j,k')^R is selected. In other words, even if relaying of k' is superimposed on the relay station j used to relay a terminal station k other than k', the desired gain G_(j,k')^R can be ensured and the gain is not unnecessarily large, so a relay station j is selected. Superimposing a relay signal can reduce the number of relay stations used, thereby saving power consumption of the relay stations.

[0054] In step S106, if there is no relay station j that satisfies the condition of norm A(2), the following (3) or (4) is executed. (3) Among the gain values ​​already assigned (set) to relay station j, a relay station j to which a gain value closest to G_(j,k')^R has been assigned is selected, and the desired gain of that relay station j is updated (changed) to G_(j,k')^R. At this time, a threshold Δ may be set for the difference in gain before and after updating (changing) the desired gain, and the update (change) may be permitted if the difference is equal to or less than this threshold Δ. A relay station j whose difference exceeds the threshold Δ is not selected. This is to reduce the power consumption of relay station j. In this way, it is possible to select a relay station j that will relay for multiple terminal stations k using the first gain (G_(j,k')^R) required for relaying terminal station k' and the gain already assigned to relay station j for relaying terminal stations k other than terminal station k'. If there is no selectable relay station j, the process proceeds to step S107. (4) Proceed to Standard B (step S107).

[0055] In step S107, the base station 2 adds the relay station j selected by the rule B as a relay station to be used. Rule B is as follows. (1) If there is only one relay station j that satisfies the condition in step S105, that relay station j is selected. (2) If there are multiple relay stations j that satisfy the condition in step S105, the following (3) or (4) is executed. (3) The relay station j for which the desired gain G_(j,k´)^R at the relay station is smallest is selected. (4) The relay station j with the most remaining battery power is selected. However, if there are both battery-powered relay stations j and relay stations j powered by commercial power, the relay stations powered by commercial power are selected with priority over the battery-powered relay stations.

[0056] In step S108, the base station 2 determines whether the current value of k' has reached N_(UE), which is the number of terminal stations k. If it is determined that the value of k' has reached N_(UE), the process of FIG. 8 ends and the process proceeds to step S06 (FIG. 7). On the other hand, if it is determined that the value of k' has not reached N_(UE), the value of k' is incremented (step S 110), and then the process returns to step S102.

[0057] If the process proceeds to step S109, the base station 2 adds the available relay station j as a relay station to be used, and the process proceeds to step S108.

[0058] 9 is a flowchart showing an example (second example) of the selection process of relay station j. The second example shows the process when relay stations whose power consumption needs to be considered are excluded from the population of relay stations j from the beginning.

[0059] In the second example, steps S101, S103 and S104 are performed, and then step S102 is performed. Except for this, the processing itself is the same as the first processing example (FIG. 8).

[0060] In step S06 (FIG. 7), base station 2 transmits a notification (message) to relay station j selected in step S05. The notification includes an instruction to relay an uplink signal from a predetermined terminal station k and an amplification gain to be set for the relay.

[0061] The relay station j selected by the base station 2 receives the notification from the base station (step S004). The relay station j that has received the notification sets the amplification gain according to the information included in the notification and performs relay processing of the signal from the terminal station k instructed in the notification (step S005). If there are multiple terminal stations k to relay the signal, the relay station j relays a signal in which signals from multiple terminal stations k are superimposed.

[0062] The communication system according to the embodiment includes a base station 2 (control circuit 22), a control device 1, or a control circuit 2A, which is a communication control device that selects a relay station j from a plurality of relay stations 3 (relay stations j) to be used for relaying uplink communication from a terminal station 4 (terminal station k) to a base station 2. Among the plurality of relay stations j, one or more relay stations that are available for relaying are excluded from those that take power consumption into consideration. The base station 2 selects a relay station j to be used for relaying from the remaining relay stations j. This reduces the power consumption of relay stations that require consideration for power consumption, such as those that are battery-powered. This means that the power consumption of relay stations j that perform non-regenerative relaying can be reduced.

[0063] The base station 2 can extract relay stations j that can be used for relaying based on a value (SINR) indicating the communication quality between each of the multiple relay stations j and the terminal station k and the gain (G_(j,k´)^R) required of each relay station j for relaying.

[0064] Relay stations j that take power consumption into consideration may include relay stations j that have transmitted a request to base station 2 to take power consumption into consideration, and relay stations j whose remaining battery charge used to drive relay station j is below a threshold.

[0065] The base station 2 can select the first relay station j, which is already used for a terminal station k other than the terminal station k', from among the relay stations j available for relaying, as the relay station to be used for relaying. This reduces the number of relay stations that perform relaying, thereby reducing power consumption.

[0066] Base station 2 can select a first relay station that satisfies the following conditions from among multiple first relay stations as the relay station to use for relaying. This allows the relay station to relay for multiple terminals, while preventing the relay gain from increasing unnecessarily and increasing power consumption. The first gain (G_(j,k´)^R ) is required for relaying terminal station k other than terminal station k'. Furthermore, the first relay station whose second gain value is closest to the first gain value is selected as the relay station to be used for relaying.

[0067] If there is no relay station requiring a second gain greater than the first gain, base station 2 can do the following. That is, base station 2 selects relay station j whose assigned gain value is closest to the first gain value as the relay station to use for relaying. At this time, base station 2 changes the gain required for the selected relay station j to the first gain. This enables the selected relay station to relay with a gain appropriate for relaying between terminal station k' and terminal station k.

[0068] If there is no relay station j already in use for a terminal station k' other than terminal station k' among the one or more relay stations available for relaying, base station 2 can do the following: Namely, base station 2 selects relay station j having the smallest required gain (G_(j,k)^R) for relaying among the one or more relay stations as the relay station to be used for relaying. This makes it possible to reduce the power consumption for relaying.

[0069] Base station 2 can send instructions to the selected relay station j to relay and instructions to set the gain to be applied when relaying. This allows relay station j, which receives the instructions, to set the gain required for relaying and relay with just the right gain (power consumption).

[0070] The above-described embodiment is merely an example, and the present disclosure may be modified as appropriate within the scope of the present disclosure. Furthermore, the processes and means described in the present disclosure may be freely combined and implemented as long as no technical contradiction occurs.

[0071] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by one device. In a computer system, the hardware configuration (server configuration) by which each function is realized can be flexibly changed.

[0072] The present disclosure can also be realized by providing a computer program implementing the functions described in the above embodiments to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer via a non-transitory computer-readable storage medium connectable to the computer's system bus or via a network. Non-transitory computer-readable storage media include any type of medium suitable for storing electronic instructions, such as any type of disk, including magnetic disks (e.g., floppy disks, hard disk drives (HDDs), etc.), optical disks (e.g., CD-ROMs, DVDs, Blu-ray disks), read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic cards, flash memory, or optical cards. [Explanation of symbols]

[0073] 1. Control device 2...Base station 3. Relay Station 4, 4A Terminal station 11. CPU 12...Main memory 13...Auxiliary storage device 21, 31, 41... Radio 22, 32, 42 Control circuit 100A, 100B...Communication Systems 311··Transmitter 312··Receiver 313··Baseband Circuit 314··Circulator

Claims

1. a communication control device that performs processing to select a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations; the communication control device selects a non-regenerative relay station to be used for the non-regenerative relay from one or more non-regenerative relay stations that can be used for the non-regenerative relay among the plurality of non-regenerative relay stations, from the remaining non-regenerative relay stations excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge used to drive the non-regenerative relay station is below the threshold, The communication control device extracts the one or more non-regenerative relay stations for which a value indicating a communication quality between each of the plurality of non-regenerative relay stations and the terminal station is equal to or greater than a predetermined value, and a gain required of each non-regenerative relay station for the non-regenerative relay is equal to or less than a maximum gain applicable to each non-regenerative relay station. Communication system.

2. A communication control device that performs processing to select a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations, the communication control device selects a non-regenerative relay station to be used for the non-regenerative relay from one or more non-regenerative relay stations that can be used for the non-regenerative relay among the plurality of non-regenerative relay stations, from the remaining non-regenerative relay stations excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge used to drive the non-regenerative relay station is below the threshold, The communication control device selects, from the one or more non-regenerative relay stations, a first relay station that is a non-regenerative relay station already being used for a terminal station other than the terminal station, as a non-regenerative relay station to be used for the non-regenerative relay; The communication control device selects, from among the plurality of first relay stations, terminal stations other than the terminal station that have a second gain greater than a first gain required for each non-regenerative relay station with respect to relaying by the terminal station. and a first relay station having a second gain value closest to a value of the first gain is selected as a non-regenerative relay station to be used for the non-regenerative relay. Communication system.

3. When there is no non-regenerative relay station for which the second gain greater than the first gain is required, the communication control device selects a non-regenerative relay station whose assigned gain value is closest to the value of the first gain as a non-regenerative relay station to be used for the non-regenerative relay, and changes the gain required of the selected non-regenerative relay station to the first gain. The communication system according to claim 2 .

4. A communication control device that performs processing to select a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations, the communication control device selects a non-regenerative relay station to be used for the non-regenerative relay from one or more non-regenerative relay stations that can be used for the non-regenerative relay among the plurality of non-regenerative relay stations, from the remaining non-regenerative relay stations excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge used to drive the non-regenerative relay station is below the threshold, When there is no non-regenerative relay station already being used for a terminal station other than the terminal station among the one or more non-regenerative relay stations, the communication control device selects, among the one or more non-regenerative relay stations, a non-regenerative relay station having the smallest gain required for the non-regenerative relay as the non-regenerative relay station to be used for the non-regenerative relay. Communication system.

5. The communication control device sends to the selected non-regenerative repeater station an instruction to perform non-regenerative repeating and an instruction to set a gain to be applied during the non-regenerative repeating. The communication system according to claim 2 .

6. A communication control device that performs a process of selecting a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations that constitute a communication system selects a non-regenerative relay station to be used for the non-regenerative relay from one or more non-regenerative relay stations that can be used for the non-regenerative relay among the plurality of non-regenerative relay stations, from the remaining non-regenerative relay stations excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge used to drive the non-regenerative relay station is below the threshold, The communication control device extracts the one or more non-regenerative relay stations for which a value indicating a communication quality between each of the plurality of non-regenerative relay stations and the terminal station is equal to or greater than a predetermined value, and a gain required of each non-regenerative relay station for the non-regenerative relay is equal to or less than a maximum gain applicable to each non-regenerative relay station. Communication control method.

7. A communication control device that performs a process of selecting a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations that constitute a communication system, selects a non-regenerative relay station to be used for said non-regenerative relay from one or more non-regenerative relay stations that can be used for said non-regenerative relay among said plurality of non-regenerative relay stations, from the remaining non-regenerative relay stations excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted said request and whose remaining battery charge used to drive the non-regenerative relay station is below said threshold, The communication control device selects a first relay station, which is a non-regenerative relay station already being used for a terminal station other than the terminal station, from among the one or more non-regenerative relay stations, as the non-regenerative relay station. Selected as a non-regenerative relay station to be used, The communication control device selects, from among the plurality of first relay stations, a first relay station for which a second gain greater than a first gain required of each non-regenerative relay station for relaying from the terminal station other than the terminal station is required for relaying, and for which the value of the second gain is closest to the value of the first gain, as a non-regenerative relay station to be used for the non-regenerative relay. Communication control method.

8. When there is no non-regenerative relay station for which the second gain greater than the first gain is required, the communication control device selects a non-regenerative relay station whose assigned gain value is closest to the value of the first gain as a non-regenerative relay station to be used for the non-regenerative relay, and changes the gain required of the selected non-regenerative relay station to the first gain. The communication control method according to claim 7.

9. A communication control device that performs a process of selecting a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations that constitute a communication system, selects a non-regenerative relay station to be used for said non-regenerative relay from one or more non-regenerative relay stations that can be used for said non-regenerative relay among said plurality of non-regenerative relay stations, from the remaining non-regenerative relay stations excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted said request and whose remaining battery charge used to drive the non-regenerative relay station is below said threshold, When there is no non-regenerative relay station already being used for a terminal station other than the terminal station among the one or more non-regenerative relay stations, the communication control device selects, among the one or more non-regenerative relay stations, a non-regenerative relay station having the smallest gain required for the non-regenerative relay as the non-regenerative relay station to be used for the non-regenerative relay. Communication control method.

10. The communication control device sends to the selected non-regenerative repeater station an instruction to perform non-regenerative repeating and an instruction to set a gain to be applied during the non-regenerative repeating. The communication control method according to claim 7.

11. A communication control device that performs processing to select a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations that constitute a communication system, a processor for selecting a non-regenerative relay station to be used for the non-regenerative relay from one or more non-regenerative relay stations usable for the non-regenerative relay among the plurality of non-regenerative relay stations, excluding a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge used to drive the non-regenerative relay station is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge used to drive the non-regenerative relay station is below the threshold, The processor extracts the one or more non-regenerative relay stations for which a value indicating a communication quality between each of the plurality of non-regenerative relay stations and the terminal station is equal to or greater than a predetermined value, and a gain required of each non-regenerative relay station for the non-regenerative relay is equal to or less than a maximum gain applicable to each non-regenerative relay station. Communications control device.

12. A communication control device that performs processing to select a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations, comprising: Among the plurality of non-regenerative relay stations, one or more non-regenerative relay stations that can be used for the non-regenerative relay are selected from a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge is below the threshold, and the remaining non-regenerative relay stations are selected from the non-regenerative relay stations that have transmitted the request and whose remaining battery charge is below the threshold. a processor for selecting a non-regenerative repeater station to be used; The processor selects, from the one or more non-regenerative relay stations, a first relay station that is a non-regenerative relay station already being used for a terminal station other than the terminal station, as a non-regenerative relay station to be used for the non-regenerative relay; The processor selects, from among the plurality of first relay stations, a first relay station for which a second gain greater than a first gain required of each non-regenerative relay station for relaying from the terminal station other than the terminal station is required for relaying, and for which the value of the second gain is closest to the value of the first gain, as a non-regenerative relay station to be used for the non-regenerative relay. Communications control device.

13. A communication control device that performs processing to select a non-regenerative relay station to be used for non-regenerative relay of uplink communication from a terminal station to a base station from among a plurality of non-regenerative relay stations, comprising: the communication control device includes a processor that selects a non-regenerative relay station to be used for the non-regenerative relay from one or more non-regenerative relay stations that can be used for the non-regenerative relay among the plurality of non-regenerative relay stations, from a non-regenerative relay station that has transmitted a request for consideration of power consumption, a non-regenerative relay station whose remaining battery charge is below a threshold, or a non-regenerative relay station that has transmitted the request and whose remaining battery charge is below the threshold, excluding the remaining non-regenerative relay station, When there is no non-regenerative relay station already being used for a terminal station other than the terminal station among the one or more non-regenerative relay stations, the processor selects, among the one or more non-regenerative relay stations, a non-regenerative relay station having the smallest gain required for the non-regenerative relay as the non-regenerative relay station to be used for the non-regenerative relay. Communications control device.

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