Communication relay equipment and program

Abstract

To provide a communication relay device and a computer program that contribute to improving communication quality in a system that relays between a base station and a mobile station.SOLUTION: A communication relay device according to an embodiment includes a detection unit and a control unit. The detection unit detects a mobile station located within a coverage area formed by a plurality of slave units. The control unit controls communication resources used by the slave units to communicate with the mobile station on the basis of a detection result by the detection unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of this invention relate to a communication relay device and a program.

Background Art

[0002] In 2020, commercial services for mobile phones using 5G (the fifth-generation mobile communication system) also started in Japan. One of the technologies attracting attention in 5G is beamforming. This is a function that realizes the expansion of coverage and the expansion of cell capacity by simultaneous communication with multiple users by causing a plurality of antenna elements on one antenna to cooperate and form a radio wave beam in an arbitrary direction, and is generally realized in combination with a massive multiple-input multiple-output (Massive MIMO) antenna.

[0003] By the way, since before 5G, there has been a distributed antenna system (DAS) as a measure for indoor coverage of mobile communication systems. The DAS system relays between a mobile station and a base station, and consists of a master unit and a plurality of slave units that are distributed. The master unit distributes the signal of one base station to a plurality of slave units, and each slave unit outputs the same downlink signal from its respective antenna to construct an area as one cell.

[0004] When the DAS system is simply applied to a 5G system, as described above, since the same signal is output from each slave unit, the beams respectively formed by the distributed slave units do not necessarily face the direction in which mobile stations exist within the coverage area. Further, in the master unit, since uplink signals from all slave units are combined and transmitted to the base station, this combination causes a factor that degrades the noise figure (NF).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The problem that this invention aims to solve is to provide a communication relay device and program that contribute to improving communication quality. [Means for solving the problem]

[0007] The communication relay device of this embodiment comprises a receiving unit, an adding unit, and a control unit. The receiving unit receives signals transmitted from multiple slave units. The adding unit adds the signals received by the receiving unit to generate a signal to be transmitted to the base station. The control unit controls the adding unit so that it does not add any signals received by the receiving unit that are not used for communication, assigns a stream corresponding to each beamforming beam, and performs an addition process on the assigned streams. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram showing a mobile communication system, including a communication relay system. [Figure 2] Figure 1 shows an example of the configuration of the master unit. [Figure 3] Figure 2 shows an example of the configuration of the UL signal processing unit. [Figure 4] Figure 3 shows an example configuration of UL MUX SW. [Figure 5] Figure 1 shows an example of the configuration of the DL signal processing unit. [Figure 6] Figure 5 shows an example configuration of DL MUX SW. [Figure 7] A flowchart illustrating the process of the master unit shown in Figure 1. [Figure 8] A diagram illustrating an example of how a distributed antenna system works. [Modes for carrying out the invention]

[0009] A communication relay system according to one embodiment will be described below with reference to the drawings. Figure 1 shows a part of the fifth-generation mobile communication system, also known as 5G. This mobile communication system consists of a 5G core network (5GC) and a radio access network (NR). In the example in Figure 1, the radio access network NR includes a communication relay system.

[0010] The 5G core network 5GC controls the wireless access network NR, aggregates traffic, and communicates with external networks (Internet IN, external telephone network EN, etc.), and is equipped with core device C at its center. Core device C performs tasks such as authentication and security management, session management, policy control, and packet forwarding.

[0011] On the other hand, the wireless access network NR comprises multiple base station devices (for example, gNB1 and gNB2 in Figure 1). Base station devices gNB1 and gNB2 are controlled by the core device C and each forms a wireless communication area (a so-called cell) that can communicate with mobile station UE (User Equipment).

[0012] More specifically, the base station equipment gNB1 communicates wirelessly with the mobile station UE via antenna equipment AN, which is installed on the rooftop of a building or on a dedicated tower, and connects the mobile station UE to the 5G core network 5GC via core equipment C. The base station equipment gNB1 also performs beamforming using Massive MIMO, which controls the phase of signals in the numerous antenna elements on antenna equipment AN, contributing to increased communication capacity and other benefits.

[0013] Base station equipment gNB2 has the same functions as base station equipment gNB1, but instead of antenna equipment AN, it communicates wirelessly with mobile station UE through distributed antenna system DAS and connects mobile station UE to the 5G core network 5GC through core equipment C.

[0014] The distributed antenna system DAS is used to form a relatively small-scale wireless communication area compared to the antenna device AN in special places (such as inside buildings, underground shopping arcades, other structures, sparsely populated or densely populated areas, areas where it is difficult or restricted to construct a tower, event venues, etc., which are temporary locations of the antenna device AN, etc.). As shown in FIG. 1, it includes a master unit MU (Master Unit), remote units RU (Remote Unit) 1 to RU3, and antennas AN1 to AN3.

[0015] The master unit MU comprehensively controls each part of the distributed antenna system DAS and serves as a communication relay device that enables the mobile station UE to communicate with the base station device gNB2 via the antennas (AN1 to AN3) and the remote units (RU1 to RU3). When the master unit MU is connected to the remote units RU1 to RU3 by optical communication lines respectively, it is generally also called an optical repeater.

[0016] The antennas AN1 to AN3 are respectively connected to the corresponding remote units RU1 to RU3 in a one-to-one manner, each consisting of a large number of antenna elements, and are corresponding to massive MIMO (Massive MIMO) in which the directivity is controlled (beamforming) by adjusting the phase of the transmitted RF signal and / or the received RF signal.

[0017] In this embodiment, for the sake of simplicity of explanation, each of the antennas AN1 to AN3 is described as performing beamforming to simultaneously form a maximum of 4 beams in arbitrary directions. Also, for the master unit MU to be described in detail later, for the sake of simplicity of explanation, it is described as processing (relaying) a maximum of 4 streams simultaneously corresponding to the above 4 beams.

[0018] Note that in an actual device, it is not limited to a maximum of 4, and it may be 3 or less or 5 or more. Also, the number of beams formed by each of the antennas AN1 to AN3 is not fixed, and may be dynamically changed by, for example, varying the number of antenna elements used.

[0019] The slave units RU1 to RU3 are each connected one-to-one to the corresponding antennas AN1 to AN3 and can be connected so as to communicate with the master unit MU via an optical communication line. Further, the slave units RU1 to RU3 can perform beamforming by phase adjustment with respect to the corresponding antennas AN1 to AN3, and can detect (search) the direction in which the mobile station UE exists by measuring the reception intensity and beamforming.

[0020] More specifically, for the uplink, the slave units RU1 to RU3 perform phase adjustment (beamforming) on each RF signal obtained by the corresponding antennas AN1 to AN3, and obtain reception RF signals corresponding to a maximum of four beams respectively. In the beamforming in the slave units RU1 to RU3, among the maximum of four beams, a beam corresponding to the number of streams assigned by the master unit MU to each mobile station UE is formed toward the mobile station UE.

[0021] Then, the slave units RU1 to RU3 down-convert the reception RF signals corresponding to each beam, and simultaneously demodulate them into four reception signals corresponding to a maximum of four beams respectively. Then, the slave units RU1 to RU3 bundle the demodulated reception signals serially, and then convert them from an electrical signal to an optical signal (modulate an optical carrier wave) and transmit them to the master unit MU through the above optical communication line. The stream included in the above reception signal is referred to as an UL stream signal.

[0022] On the other hand, for the downlink, the slave units RU1 to RU3 convert the optical signal transmitted from the master unit MU through the above optical communication line into an electrical signal, and simultaneously demodulate it into signals (hereinafter referred to as DL stream signals) corresponding to a maximum of four streams respectively.

[0023] Then, the sub-units RU1 to RU3 generate a transmit RF signal by modulating the carrier wave using the DL stream signal, and output this transmit RF signal to the connected antennas AN1 to AN3, respectively, radiating it into space. Each of the sub-units RU1 to RU3 is capable of beamforming, forming up to four beams simultaneously, and forms a beam for each DL stream signal for transmission. That is, if four DL stream signals are obtained through demodulation, four beams are formed, and each beam transmits one DL stream signal.

[0024] Next, the master unit MU will be described in detail. Figure 2 shows an example of the configuration of the master unit MU. Specifically, the master unit MU comprises ports P1 to P3, a transmission unit 10, an UL (Up Link) signal processing unit 20, a DL (Down Link) signal processing unit 30, and a control unit 100. Ports P1 to P3 correspond to slave units RU1 to RU3, respectively, allowing for one-to-one connection to the optical communication line, and are also connected to the UL signal processing unit 20 and the DL signal processing unit 30.

[0025] Regarding the uplink, ports P1 to P3 convert the optical signals sent from their respective slave units RU1 to RU3 into electrical signals, demodulate them into up to four received signals corresponding to each beam (received signals for each beam demodulated by slave units RU1 to RU3), and output them in parallel. Each of these demodulated received signals is output to the UL signal processing unit 20.

[0026] Ports P1 to P3 function as information acquisition units that obtain information sent from slave units RU1 to RU3 from each received signal. They monitor each demodulated received signal and detect communication initiation requests (PRACH) from mobile stations UE contained in these received signals, as well as the stream IDs assigned to each received signal (UL stream signal). Furthermore, ports P1 to P3 function as location detection units and, based on the above detection results, detect the presence of mobile stations UE located within the coverage area formed by each slave unit RU1 to RU3. These detection results are notified to the control unit 100.

[0027] On the other hand, for the downlink, ports P1 to P3 each receive a maximum of four DL stream signals simultaneously from the DL signal processing unit 30. Ports P1 to P3 then bundle the received DL stream signals serially, convert them from electrical signals to optical signals (modulation of the optical carrier wave), and transmit them to their respective slave units RU1 to RU3 via the optical communication line.

[0028] The transmission unit 10 receives the communication line connected to the base station device gNB2 and communicates with the base station device gNB2 through this communication line. Specifically, for the uplink, the transmission unit 10 transmits UL signals (up to 4 simultaneously) input from the UL signal processing unit 20 to the base station device gNB2. On the other hand, for the downlink, the transmission unit 10 receives DL signals (up to 4 simultaneously) transmitted from the base station device gNB2 through the above communication line and outputs them to the DL signal processing unit 30.

[0029] The UL signal processing unit 20 performs a signal summing process, selectively adding the received signals of each beam input from ports P1 to P3, in accordance with the control of the control unit 100, and outputs it to the transmission unit 10 as a UL signal. The above signal summing process will be described in detail later.

[0030] The DL signal processing unit 30 performs signal distribution processing to selectively distribute the DL signals input from the transmission unit 10 to ports P1 to P3, in accordance with the control of the control unit 100. The above signal distribution processing will be described in detail later.

[0031] The control unit 100 is a control center that comprehensively controls each part of the master unit MU. It includes a memory (not shown) for storing control programs and control data, and a processor (not shown) for executing processing based on the control programs and control data. These components enable various control functions. Details of the control will be described in the operation description below.

[0032] Next, with reference to Figure 3, an example configuration of the UL signal processing unit 20 will be described. The UL signal processing unit 20 comprises uplink multiplexer switches (UL MUX SW) 211-213 and addition processing units 221-224.

[0033] UL MUX SW211~213 each correspond one-to-one with ports P1~P3, and receive up to four received signals output from ports P1~P3. These signals are selectively multiplexed according to the UL switching signals α, β, and γ from the control unit 100 and output.

[0034] Here, with reference to Figure 4, an example configuration of UL MUX SW211 will be described. Note that the configurations of UL MUX SW212 and 213 are similar, so their explanation will be omitted. However, the UL switching signals α, β, and γ may differ from each other. The UL MUX SW211 comprises a switching control unit 2110, multiplexers 2111-2114, and an output switch 2115.

[0035] Each of the multiplexers 2111 to 2114 has four input terminals and receives up to four received signals output from port P1. Then, according to instructions from the switching control unit 2110, the input received signals are selectively multiplexed and output as multiplexed received signals to the output switch 2115.

[0036] The output switch 2115 has four independent switches corresponding to the multiplexers 2111-2114, and each switch receives a multiplexed received signal from its corresponding multiplexer 2111-2114. Then, according to instructions from the switching control unit 2110, the multiplexed received signal is output from the output terminal of the switch. This output terminal is the output terminal of the UL MUX SW211.

[0037] The switching control unit 2110 controls the multiplexers 2111-2114 and the output switch 2115 according to the UL switching signal α from the control unit 100, thereby controlling multiplexing and output. In other words, by controlling according to the UL switching signal α, up to four received signals output from port P1 are selectively multiplexed, and the output and output destination of the multiplexed received signals are controlled.

[0038] Refer to Figure 3 again. Each of the addition processing units 221 to 224 has three input terminals and is connected to one of the four output terminals of each of the UL MUX SWs 211 to 213, and the multiplexed received signals are input to the three input terminals. The addition processing units 221 to 224 then add (combine) up to three multiplexed received signals and output this added multiplexed received signal as a UL signal to the transmission unit 10.

[0039] Next, with reference to Figure 5, an example configuration of the DL signal processing unit 30 will be described. The DL signal processing unit 30 includes downlink multiplexer switches (DL MUX SW) 311 to 313.

[0040] DL MUX SW311~313 each correspond one-to-one with ports P1~P3, and each receives up to four DL signals output from the transmission unit 10. These DL signals are selectively multiplexed according to the DL switching signals χ, ψ, and ω from the control unit 100 and output to the corresponding ports P1~P3. It is also possible to output without multiplexing.

[0041] Here, with reference to Figure 6, an example configuration of DL MUX SW311 will be described. Note that the configurations of DL MUX SW312 and 313 are similar, so their explanation will be omitted. However, the DL switching signals χ, ψ, and ω can be different from each other. The DL MUX SW311 includes a switching control unit 3110 and multiplexers 3111 to 3114.

[0042] Each of the multiplexers 3111 to 3114 has four input terminals, and up to four DL signals output from the transmission unit 10 are distributed and input to each of them. Then, according to instructions from the switching control unit 2110, the multiplexers 3111 to 3114 selectively multiplex the input DL signals and output them as a single signal. Each of the multiplexers 3111 to 3114 corresponds one-to-one to one of the four input terminals of port P1, and outputs the signal obtained by the multiplexing to the corresponding input terminal of port P1.

[0043] The switching control unit 3110 controls the multiplexers 3111 to 3114 according to the DL switching signal χ from the control unit 100, thereby controlling multiplexing and output. In other words, by controlling the switching control unit 3110 according to the DL switching signal χ, up to four DL signals are selectively multiplexed and can be output to any or all of the four input terminals of port P1.

[0044] Next, the operation of the above-mentioned communication relay system will be explained. In particular, the operation of the distributed antenna system DAS will be explained below. Figure 7 is a flowchart illustrating the control flow of the control unit 100 of the master unit MU.

[0045] When the distributed antenna system DAS is put into operation, the control unit 100 executes the process shown in Figure 7 to monitor detection results notified from ports P1 to P3 and to monitor communication (communication start, communication in progress, communication end) through each slave unit RU1 to RU3. In other words, it monitors and waits for a communication start request to be generated from a mobile station UE located in the coverage area formed by each slave unit RU1 to RU3, and for a communication session being conducted by a mobile station UE in the same coverage area to end.

[0046] For example, if a mobile station UE located within the coverage area of ​​slave unit RU1 sends a communication start request, the communication start request is received by antenna AN1 and slave unit RU1, and reaches port P1 of master unit MU via the optical communication line. An example of such a communication start request is a signal such as PRACH (Physical Random Access Channel).

[0047] When the above communication initiation request arrives at port P1, it detects the occurrence of the communication initiation request and notifies the control unit 100 of this. In response, the control unit 100 recognizes that the port that sent the notification is P1 and proceeds to step 701.

[0048] The above example illustrates the detection of a communication start request via the slave unit RU1. However, the same operation is performed for the slave unit RU2 (or RU3), and a notification is sent from port P2 (or P3). The control unit 100 then recognizes that a notification has been received from P2 (or P3).

[0049] In the initial state of the distributed antenna system DAS, the master unit MU distributes the DL signal from the base station equipment gNB2 to each slave unit RU1-RU3 for the downlink stream. In the initial state, slave units RU1-RU3 transmit DL signals by forming beams in the same direction according to the same algorithm. However, it is possible to set different settings for slave units RU1-RU3 as an initial setting to form beams in predetermined directions.

[0050] In step 701, the control unit 100 obtains detection results from all ports P1 to P3, counts the number of mobile station UEs in communication for each slave unit RU1 to RU3 based on these detection results, and then proceeds to step 702.

[0051] One way to count the number of mobile station UEs in communication is, for example, that ports P1 to P3 or the control unit 100 monitor the PRACH transmitted from the mobile station UEs to the base station equipment gNB2, and count the number of PRACHs for each slave unit RU1 to RU3, distinguishing between mobile station UEs.

[0052] In step 702, the control unit 100 executes the stream assignment process and proceeds to step 703. Specifically, the control unit 100 assigns stream IDs 1 to 4 to the mobile station UE that made the communication start request or to the mobile station UE that is already in communication, according to a predetermined stream assignment algorithm, and then proceeds to step 703. Note that for mobile station UEs that are already in communication, the assigned stream ID will be reviewed, but it is also possible to leave it unchanged.

[0053] The above stream assignment algorithm can take various factors into consideration, but for example, it can determine the stream ID to be assigned to each mobile station UE based on the number of streams that the master unit MU can process (4 in this example), the number of slave units that the master unit MU accommodates (3 in this example, RU1 to RU3), the number of mobile station UEs present within the coverage area of ​​each slave unit RU1 to RU3 (for example, the number of PRACHs recognized by the control unit 100), the maximum number of streams between the master unit MU and each slave unit RU1 to RU3 (4 in this example), the maximum number of streams between each slave unit RU1 to RU3 and the mobile station UE (4 in this example), the communication quality of each resource, the type of communication used by the mobile station UE, and the communication capabilities of the mobile station UE.

[0054] Furthermore, information concerning the master unit MU and slave units RU1-RU3 may be pre-stored in the master unit MU's memory unit (not shown). Information concerning slave units RU1-RU3 and mobile station UE may also be dynamically acquired by the control unit 100 from slave units RU1-RU3 and mobile station UE via ports P1-P3.

[0055] In step 703, the control unit 100 notifies each slave unit RU1 to RU3 of the stream ID assigned to the mobile station UE in step 702, and then proceeds to step 704. Specifically, it notifies each slave unit RU1 to RU3 of, for example, the identification information of the mobile station UE and the assigned stream ID in association.

[0056] Furthermore, each slave unit RU1 to RU3 that receives the notification will secure communication resources corresponding to the number of notified stream IDs for each mobile station UE, and establish a communication link with each mobile station UE according to a predetermined procedure.

[0057] In step 704, the control unit 100 performs signal summing on the four signals output from each port P1 to P3 based on the stream ID assigned to the mobile station UE in step 702, thereby generating four UL signals and proceeding to step 705.

[0058] This signal summing process selectively adds the four signals output from each of the ports P1 to P3 to generate four UL signals. Some or all of the signals that do not include the stream sent from the mobile station UE are excluded from the summing process. As a result, at least the signals that include the stream sent from the mobile station UE will be included in one of the four UL signals.

[0059] More specifically, the control unit 100 controls the signal addition process of the UL signal processing unit 20 by generating UL switching signals α, β, and γ to add the signals corresponding to the assigned stream ID from the four signals output from each port P1 to P3, based on the stream ID assigned to the mobile station UE in step 702.

[0060] In step 705, the control unit 100 controls the UL signal processing unit 20 and the transmission unit 10 to start the transmission of the four UL signals obtained by the signal summing process of the UL signal processing unit 20 to the base station device gNB2 via the transmission unit 10, and then terminates the process.

[0061] Thereafter, the control unit 100 restarts the process shown in Figure 7, monitors the detection results notified from ports P1 to P3, and monitors communication (communication start, communication in progress, communication end) for each slave unit RU1 to RU3. If a communication start request is generated from a mobile station UE located in the coverage area formed by each slave unit RU1 to RU3, or if a communication session conducted by a mobile station UE in the same coverage area ends, the process from step 701 onwards is executed again.

[0062] Next, we will explain the operation with a specific example, referring to Figure 8. As shown in Figure 8(a), consider the case where, among the slave units RU1 to RU3, there is a mobile station UE1 that requests communication only within the coverage area of ​​slave unit RU1, that is, a communication start request is sent from mobile station UE1, and there are no mobile stations in the coverage areas of the other slave units RU2 and RU3.

[0063] In this case, the control unit 100 recognizes from the detection results of each port P1 to P3 obtained in step 701 that the mobile station UE1 exists only in the coverage area of ​​the slave unit RU1, and uses the stream allocation algorithm in step 702 to assign, for example, all four streams ID1 to ID4 to the slave unit RU1, and assign zero streams to the remaining slave units RU2 and RU3.

[0064] As a result, in step 703, the slave unit RU1 notifies the mobile station UE1 that it will assign streams ID1 to ID4, secures communication resources for these four streams (UL stream signals), and establishes a communication link with the mobile station UE1 for communication using the four streams according to a predetermined procedure. More specifically, in order to receive the four UL stream signals, antenna AN1 forms all four beams that can be formed, i.e., beams corresponding to streams ID1 to ID4, towards the mobile station UE1.

[0065] Meanwhile, in the master unit MU, the control unit 100 recognizes that, having assigned stream IDs 1 to 4 to the mobile station UE1 in step 702, streams 1 to 4 have been assigned to slave unit RU1, and 0 streams have been assigned to the remaining slave units RU2 and RU3. It then generates UL switching signals α, β, and γ to add the signals corresponding to the assigned stream IDs.

[0066] At this time, the UL switching signal α is a signal that instructs the UL MUX SW211 to output four signals corresponding to the four beams of the slave unit RU1, which are input from port P1, to the corresponding summing processing units 221 to 224.

[0067] On the other hand, the UL switching signal β is a signal that instructs the UL MUX SW212 not to output some or all of the four signals corresponding to the four beams of the slave unit RU2, which are input from port P2, to the summing processing units 221-224.

[0068] Similarly, the UL switching signal γ is a signal that instructs the UL MUX SW213 not to output some or all of the four signals corresponding to the four beams of the slave unit RU3, which are input from port P3, to the summing processing units 221-224.

[0069] As a result, the addition processing units 221 to 224 output the signals of the four streams ID1 to ID4 of the slave unit RU1 input from port P1 to the transmission unit 10, with little to no addition of the signals from the other slave units RU2 and Ru3. In this way, the addition processing units 221 to 224 suppress the addition of signals that are not expected to be used for communication to signals that are actually used for communication.

[0070] Next, we will explain the example shown in Figure 8(b). In this example, there is one mobile station UE (UE1, UE2, UE3) in each of the coverage areas of slave units RU1 to RU3. Alternatively, one could consider the situation as follows: from the state shown in Figure 7(a) (where only mobile station UE1 exists), mobile stations UE2 and UE3 move into the respective coverage areas of slave units RU2 and RU3 (or, mobile stations UE2 and UE3, which originally existed in the respective coverage areas of slave units RU2 and RU3, respectively, initiate communication from a state where they were not communicating).

[0071] In this case, the control unit 100 recognizes from the detection results of each port P1 to P3 obtained in step 701 that there is one mobile station UE (UE1, UE2, UE3) in each coverage area of ​​slave units RU1 to RU3, and that the three mobile stations each request communication. Then, using the stream assignment algorithm described in step 702, the control unit 100 assigns, for example, two stream IDs 1 and 2 to slave unit RU1, and one stream ID 3 and 4 to the remaining slave units RU2 and RU3, respectively.

[0072] There are various reasons why the number of streams allocated to slave RU1 may be greater than that of slave RU2 and RU3. For example, (1) mobile station UE1 was already communicating before mobile stations UE2 and UE3, (2) the wireless transmission path environment was better (or worse) for mobile station UE1 than for mobile stations UE2 and UE3, (3) the type of communication required more resources for mobile station UE1 than for mobile stations UE2 and UE3, (4) mobile station UE1 was a device that had higher priority than mobile stations UE2 and UE3 (e.g., an administrator, a user of a special service), or (5) mobile station UE1 was a device with higher communication performance than mobile stations UE2 and UE3 (for example, mobile stations UE2 and UE3 did not have the capability to use two streams). It is conceivable to prioritize these conditions and then execute the stream allocation process in step 702.

[0073] As a result, in step 703, the slave unit RU1 notifies the mobile station UE1 that it will assign stream IDs 1 and 2, securing communication resources for the two streams (UL stream signals), and establishing a communication link with the mobile station UE1 for communication using the two streams according to a predetermined procedure. More specifically, in order to receive the two UL stream signals, two of the four beams that can be formed by antenna AN1, namely beams corresponding to stream IDs 1 and 2 respectively, are formed and directed towards the mobile station UE1.

[0074] Similarly, in step 703, the slave unit RU2 notifies the mobile station UE2 that it will assign stream ID 3, securing communication resources for one stream (UL stream signal), and establishing a communication link with the mobile station UE2 for communication on one stream according to a predetermined procedure. More specifically, in order to receive one UL stream signal, one of the four beams that can be formed by antenna AN2, i.e., the beam corresponding to stream ID 3, is formed in the direction of the mobile station UE2.

[0075] Similarly, in step 703, the slave unit RU3 notifies the mobile station UE3 that it will assign stream ID 4, thereby securing communication resources for one stream (UL stream signal), and establishing a communication link with the mobile station UE3 for communication on one stream according to a predetermined procedure. More specifically, in order to receive one UL stream signal, one of the four beams that can be formed by antenna AN3, i.e., the beam corresponding to stream ID 4, is formed in the direction of the mobile station UE3.

[0076] Meanwhile, in the master unit MU, the control unit 100 generates UL switching signals α, β, and γ based on the fact that in step 702, it assigned two stream IDs, ID1 and ID2, to mobile station UE1, and one stream ID, ID3, and ID4, to mobile stations UE2 and UE3, respectively.

[0077] At this time, the UL switching signal α is a signal that instructs the UL MUX SW211 to output the signals corresponding to stream ID1 and ID2, which are among the four signals corresponding to the four beams of the slave unit RU1 input from port P1, to the summing processing units 221 and 222.

[0078] On the other hand, the UL switching signal β is an instruction signal to the UL MUX SW212 that, of the four signals corresponding to the four beams of the slave unit RU2 input from port P2, the signal corresponding to stream ID3 must be output to the addition processing unit 223, while the remaining three signals are not output to the addition processing units 221-224, either partially or entirely.

[0079] Similarly, the UL switching signal γ is an instruction signal to the UL MUX SW213 that, of the four signals corresponding to the four beams of the slave unit RU3 input from port P3, the signal corresponding to stream ID 4 must be output to the addition processing unit 223, while the remaining three signals are not output to the addition processing units 221-224, either partially or entirely. In other words, the UL switching signals α, β, and γ are signals that include instructions to prevent some or all of the signals not used for communication from being output to the addition processing units 221-224.

[0080] As a result, the addition processing units 221 and 222 output the signals of the two streams ID1 and ID2 from the slave unit RU1 input from port P1 to the transmission unit 10, respectively, with little to no addition of the signals from the other slave units RU2 and RU3.

[0081] Similarly, the addition processing unit 223 outputs the signal of one stream ID3 from slave unit RU2, which is input from port P2, to the transmission unit 10 with little to no addition of the signals from the other slave units RU1 and RU3.

[0082] Similarly, the addition processing unit 224 outputs the signal of one stream ID 4 from slave unit RU3, which is input from port P3, to the transmission unit 10 with little to no addition of the signals from the other slave units RU1 and RU2. In other words, the addition processing units 221-224 prevent the addition of signals not used for communication (signals not expected to be used for communication) to signals actually used for communication.

[0083] As described above, in the communication relay system with the above configuration, the distributed antenna system DAS, which has multiple slave units RU1 to RU3, autonomously assigns the necessary streams to each slave unit, and each slave unit autonomously performs beamforming for the assigned stream.

[0084] Therefore, the communication relay system with the above configuration allocates communication resources to each slave unit according to the presence of a mobile station, which allows for efficient use of communication resources in the distributed antenna system DAS and ultimately contributes to improving communication quality.

[0085] Furthermore, in the above-described communication relay system, when the master unit MU, which connects multiple slave units RU1 to RU3 to the base station device gNB2, adds (combines) the received signals from the slave units RU1 to RU3 and transmits them to the base station device gNB2, it ensures that some or all of the signals not used for communication (signals for which communication is not expected) are not added.

[0086] Therefore, with the above-described communication relay system configuration, the addition of unnecessary signal components to the signal transmitted from the master unit MU to the base station equipment gNB2 is suppressed, thereby improving NF degradation and contributing to improved communication quality.

[0087] It should be noted that this invention is not limited to the embodiments described above, and in the implementation stage, the components can be modified and implemented without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments. For example, a configuration in which some components are removed from all the components shown in the embodiments is also conceivable. Moreover, components described in different embodiments may be appropriately combined.

[0088] For example, in the above embodiment, the case in which the base station device gNB2 is directly connected to the distributed antenna system DAS was described as an example. However, a repeater may be provided between the base station device gNB2 and the distributed antenna system DAS to increase the number of distributions, so that multiple distributed antenna systems DAS are connected to the base station device gNB2.

[0089] Furthermore, in the above embodiment, the control unit 100 of the master unit MU determined the streams to be assigned to each slave unit RU1 to RU3, but this is not limited to this. For example, the control units of the slave units RU1 to RU3 may determine the number of streams they will use based on the number of mobile station UEs in their coverage area or the number of available streams notified by the master unit MU. Alternatively, the repeater described above may perform the same processing as the control unit 100 and assign streams to each distributed antenna system DAS.

[0090] Furthermore, in the above embodiment, it was explained that in the initial control state shown in Figure 7, the master unit MU distributes and outputs DL signals from the base station device gNB2 to each slave unit RU1 to RU3 for the downlink stream. However, as shown in Figures 5 and 6, the master unit MU has a function to selectively output up to four DL signals sent from the base station device gNB2 to any port P1 to P3 according to the DL switching signals χ, ψ, and ω from the control unit 100.

[0091] Therefore, for example, after the uplink stream allocation process in step 702 has been performed, the results of this allocation may be referenced, and the same number of downlink streams may be allocated to the slave devices (RU1 to RU3) that were allocated uplink streams, causing each slave device RU1 to RU3 to transmit the corresponding downlink streams. It goes without saying that the invention can also be implemented in a similar manner by making various modifications without departing from the spirit of the invention. [Explanation of Symbols]

[0092] 10...Transmission unit, 20...UL signal processing unit, 30...DL signal processing unit, 100...Control unit, 211~213...UL MUX SW, 221~224...Addition processing unit, 311~313...DL MUX SW, 2110...Switching control unit, 2111~2114...Multiplexer, 2115...Output switch, 3110...Switching control unit, 3111~3114...Multiplexer, 5GC...G core network, AN1~AN3...Antenna, MU...Master unit, P1~P3...Port, RU1~RU3...Slave unit, UE...Mobile station, UE1~UE3...Mobile station, gNB1...Base station equipment, gNB2...Base station equipment.

Claims

1. A communication relay device that can connect to multiple slave units that communicate wirelessly with a mobile station, and transmits signals transmitted from the mobile station through the slave units to a base station, A receiving unit that receives signals transmitted from each of the aforementioned multiple slave units, This receiving unit adds the received signals and generates an adder that transmits the signal to the base station, The receiving unit controls the summing unit so that it does not add any signals that are not used for communication from among the signals it receives, assigns a stream corresponding to each beam of beamforming, and performs an addition process on the assigned streams. A communication relay device equipped with the following:

2. Furthermore, it includes an acquisition unit that acquires information from the slave unit, The control unit controls the addition unit so that it does not add any signals that are not used for communication from among the signals received by the receiving unit, based on the information acquired by the acquisition unit. The communication relay device according to claim 1.

3. A computer used in a communication relay device that can connect multiple slave units to a mobile station for wireless communication, and which transmits signals transmitted from the mobile station through the slave units to a base station, A receiving unit that receives signals transmitted from multiple slave units, This receiving unit adds the received signals and generates an adder that transmits the signal to the base station, The receiving unit controls the summing unit so that it does not add any signals that are not used for communication from among the signals it receives, assigns a stream corresponding to each beam of beamforming, and performs an addition process on the assigned streams. A program that makes something work.

Images