Communication relay system and wireless device

Abstract

To provide a communication relay system and a wireless device that can efficiently utilize wireless resources by coordinating a plurality of slave units.SOLUTION: A communication relay system has a host unit capable of transmitting / receiving signals to / from a base station and a plurality of slave units for transmitting signals to / from the host unit and wirelessly communicating with the mobile station, in order to transmit wireless signals related to wireless communication between the base station and a mobile station, and comprises a detection unit, a determination unit, and an allocation unit. The detection unit detects that the mobile station exists in a position where wireless communication can be performed with the plurality of slave units. The determination unit determines to which one of the plurality of slave units a communication resource for performing wireless communication with the mobile station existing in the position where the wireless communication can be performed is to be allocated. The allocation unit allocates the communication resource to the slave unit, according to a determination result of the determination unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a communication relay system and a wireless device.

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 enables the expansion of the wireless communication area (coverage area) and the expansion of cell capacity through simultaneous communication with multiple users by causing multiple antenna elements on one antenna to cooperate to 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, in a mobile communication system, as a measure for enabling wireless communication indoors, a distributed antenna system (DAS) has been used. The DAS system relays and transmits signals related to communication between a mobile station and a base station, and includes 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 the 5G system, as described above, the same signal is output from each slave unit, and as a result, the distributed slave units each form a beam in the same direction (azimuth), so the radio resources are not utilized efficiently.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem to be solved by the present invention is to provide a communication relay system and a wireless device that can efficiently utilize wireless resources by coordinating a plurality of slave devices.

Means for Solving the Problems

[0007] The communication relay system according to the embodiment includes a master device capable of transmitting and receiving signals to and from the base station for transmitting a wireless signal related to wireless communication between the base station and the mobile station, and a plurality of slave devices capable of transmitting signals to and from the master device and performing wireless communication with the mobile station, and includes a detection unit, a determination unit, and an allocation unit. The detection unit detects the presence of a mobile station at a position where wireless communication with a plurality of slave devices is possible, the determination unit determines which of the plurality of slave devices to allocate communication resources for performing wireless communication with the mobile station present at the position where the wireless communication is possible, and the allocation unit allocates communication resources to the slave device according to the determination result of the determination unit.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, a communication relay system according to an embodiment will be described. FIG. 1 shows a part of the fifth-generation mobile communication system, so-called 5G. This mobile communication system includes a 5G core network (5th Generation Core network) 5GC and a radio access network NR (New radio). In the example of FIG. 1, the radio access network NR includes a communication relay system.

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

[0011] On the other hand, the radio access network NR includes a plurality of base station devices (for example, gNB (gNodeB) 1 and gNB2 in FIG. 1). The base station devices gNB1 and gNB2 are controlled by the core device C and form areas (so-called cells or coverage areas) that can communicate wirelessly with mobile stations UE (User Equipment) respectively.

[0012] More specifically, the base station device gNB1 communicates wirelessly with the mobile station UE within the coverage area through the antenna device AN installed on the roof of a building or a dedicated iron tower, and connects the mobile station UE to the 5G core network 5GC through the core device C.

[0013] Also, the base station device gNB1 performs beamforming by massive MIMO (Massive MIMO) that controls the phases of signals in a large number of antenna elements on the antenna device AN, contributing to an increase in communication capacity and the like.

[0014] The base station device gNB2 has the same functions as the base station device gNB1. However, instead of the antenna device AN, it communicates wirelessly with the mobile station UE through a distributed antenna system DAS and connects the mobile station UE to the 5G core network NW through the core device C.

[0015] The distributed antenna system DAS is an example of the communication relay system according to the present embodiment. It is used to form a relatively small coverage area compared to the antenna device AN in special places (for example, temporary locations of the antenna device AN such as inside buildings, underground malls, other structures, sparsely populated or densely populated areas, areas where it is difficult or restricted to construct a tower, event venues, 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.

[0016] Note that in FIG. 1, the distributed antenna system DAS is shown within the radio access network NR, but it is not necessarily controlled by the 5G core network 5GC or the base station device gNB2. The distributed antenna system DAS can perform controls such as beamforming autonomously.

[0017] The master unit MU comprehensively controls each part of the distributed antenna system DAS. It is connected to the base station device gNB2 (for example, the base station device of communication carrier A) shown in FIG. 1 by a coaxial cable (for example, a 4×4 MIMO configuration with 4 coaxial cables in the 100 MHz band). Similarly, it is connected to the base station devices gNB2 of other communication carriers B and C (not shown) by separate coaxial cables. That is, the master unit MU is connected to each gNodeB of multiple communication carriers A, B, and C by coaxial cables respectively.

[0018] In addition, the master unit MU connects the mobile station UE connected via the antennas AN1 to AN3 and the corresponding remote units RU1 to RU3 to the base station device gNB2 of the communication carrier to which the user of the mobile station UE subscribes, and serves as a communication relay device.

[0019] Antennas AN1 to AN3 are each connected one-to-one to the corresponding slave units RU1 to RU3, each having a number of antenna elements, and are compatible with massive MIMO (Massive Multiple-Input Multiple-Output) in which directivity is controlled (beamforming) by phase adjustment of transmitted RF signals and / or received RF signals. Note that, for example, the antenna elements are grouped in 4×4 units, with 4 groups, and the directivity can be controlled for each group.

[0020] In this embodiment, for the sake of simplicity, each of the antennas AN1 to AN3 will be described as performing beamforming to simultaneously form up to 4 beams in an arbitrary direction corresponding to the above groups. Also, for the master unit MU, which will be described in detail later, for the sake of simplicity, it will be described as processing (relaying) up to 4 streams simultaneously corresponding to the above 4 beams.

[0021] 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, for example, by varying the number of antenna elements used.

[0022] The slave units RU1 to RU3 are, as described above, 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. As a connection method, as shown in FIG. 1, in addition to the slave units RU1 to RU3 being connected to the master unit MU by a daisy chain method, a method in which the slave units RU1 to RU3 are each directly connected to the master unit MU (star type, not shown) is also conceivable.

[0023] In the following description, in order to avoid redundant explanations and confusion in the correspondence of the configuration, it may be described as "slave unit RUn". When described as "slave unit RUn", it is a description common to all of the slave units RU1 to RU3. That is, "n" can be read as any of 1 to 3.

[0024] Similarly, it may be described as "antenna ANn". In this case, it means the antenna connected to the slave unit RUn, and it is any one of antennas AN1 to AN3. That is, "n" can be read as any number from 1 to 3, and the antenna ANn is connected to the slave unit RUn.

[0025] The slave unit RUn is capable of performing beamforming by phase adjustment for the antenna ANn, and detecting (searching) the direction in which the mobile station UE exists by measuring the received signal strength and the above-mentioned beamforming. Furthermore, it can communicate while following the moving mobile station UE.

[0026] More specifically regarding beamforming, for the uplink, the slave unit RUn performs phase adjustment (beamforming) on the RF signal obtained by the antenna ANn. In this example, as described above, the antenna ANn can simultaneously obtain received RF signals corresponding to a maximum of 4 beams, and also corresponds to the frequency bands of any of the above-mentioned three communication carriers.

[0027] Then, the slave unit RUn down-converts the received RF signal corresponding to each beam and demodulates it into 4 received signals respectively corresponding to a maximum of 4 beams at the same time. Then, the slave unit RUn bundles the demodulated received signals serially and then converts them from electrical signals to optical signals (modulating the optical carrier wave) and transmits them to the master unit MU through the above optical communication line. The stream included in the received signal is referred to as the UL stream signal.

[0028] On the other hand, for the downlink, the slave unit RUn detects the optical signal addressed to its own unit (slave unit RUn) from the optical signals transmitted from the master unit MU through the above optical communication line, converts the optical signal into an electrical signal, and simultaneously demodulates it into signals (hereinafter referred to as DL stream signals) respectively corresponding to a maximum of 4 streams.

[0029] Then, the slave unit RUn uses the above DL stream signal to generate a transmitted RF signal obtained by modulating a carrier wave in a frequency band corresponding to a communication carrier, outputs this transmitted RF signal to the antenna ANn, and radiates it into space. In this example, as described above, the antenna ANn is capable of beamforming to form a beam for every maximum of four DL stream signals, and also corresponds to the frequency bands of any of the three communication carriers described above.

[0030] Next, the master unit MU will be described in detail. FIG. 2 shows a configuration example of the master unit MU. That is, the master unit MU includes a port P, a control unit 100, a transmission unit 110, an UL (Up Link) signal processing unit 120, a DL (Down Link) signal processing unit 130, and a storage unit 140.

[0031] The port P accommodates a plurality of optical communication lines (for example, 25 Gbit / s per line) from the outside, is connected to the slave unit RU1 via this optical communication line, and is connected to the UL signal processing unit 120 and the DL signal processing unit 130 inside.

[0032] In the example of FIG. 2, although the slave unit RU1 is physically directly connected via the optical communication line, since optical signals exchanged between the slave units RU2 and RU3 are also multiplexed on the above optical communication line, the port P is substantially connected to the slave units RU2 and RU3, and communication (transmission and reception of optical signals) with any of the slave units RU1 to RU3 is possible by optical signals.

[0033] Regarding the uplink, the port P demultiplexes the optical signal sent from the slave unit RU1, separates it into a plurality of optical signals, converts each optical signal into an electrical signal and demodulates it to obtain a plurality of electrical communication signals. These plurality of electrical communication signals are received signals (that is, UL stream signals) corresponding to the respective beams in the slave units RU1 to RU3, and are output to the UL signal processing unit 120 in parallel.

[0034] Port P functions as an information detection unit that detects information sent from slave units RU1 to RU3 included in each received signal. For example, it monitors the received signal to detect a communication start request (PRACH) from the mobile station UE included in this received signal, and to detect the stream ID assigned to each received signal (UL stream signal).

[0035] Also, due to the function of Port P as an information detection unit, identification information of the transmission source (any one of slave units RU1 to RU3) is detected from the received signal, and for each of slave units RU1 to RU3, identification information of the mobile station UE located within the coverage area, position information (beam ID to be described later) indicating the position within the coverage area of the mobile station UE, and carrier ID indicating the communication carrier to which the user of the mobile station UE subscribes are detected. These detection results are notified to the control unit 100.

[0036] On the other hand, for the downlink, a DL stream signal from the DL signal processing unit 130 is input to Port P. Then, Port P adds identification information of the slave units RU1 to RU3 that are the destinations of the input DL stream signal, converts the electrical signal to an optical signal (modulation of the optical carrier), multiplexes these optical signals, and transmits them to the slave units RU1 to RU3 through the optical communication line.

[0037] The transmission unit 110 houses communication lines (coaxial cables) connected to the base station apparatuses gNB2 of each communication carriers A, B, and C, respectively, and communicates with the base station apparatuses gNB2 of each company through these communication lines. Specifically, for the uplink, the transmission unit 110 transmits the UL signal input from the UL signal processing unit 120 to the base station apparatus gNB2 of the corresponding communication carrier. On the other hand, for the downlink, the transmission unit 110 receives the DL stream signal transmitted from the base station apparatus gNB2 of each communication carrier through the communication line and outputs it to the DL signal processing unit 130.

[0038] The UL signal processing unit 120 performs a signal addition process of adding the received signals of each beam input from the port P for each communication carrier according to the control of the control unit 100, and outputs the signals to the transmission unit 110 as the above UL signals for each communication carrier.

[0039] The DL signal processing unit 130 performs a multiplexing process of multiplexing the DL stream signals of each communication carrier input from the transmission unit 110 and outputting them to the port P according to the control of the control unit 100.

[0040] The control unit 100 is a control center that comprehensively controls each part of the master unit MU, and includes a work memory (not shown) and a processor (not shown) that executes processing based on a control program and control data read from the storage unit 140 described later into the work memory, and realizes various control functions through these. Note that the control unit 100 is an example of a detection unit, a determination unit, an allocation unit, and a resource detection unit.

[0041] As specific control, the control unit 100 performs communication relay control between the mobile station UE and the base station device gNB2 through the slave units RU1 to RU3, and based on the detection results notified from the port P, the DL stream signals transmitted from the base station device gNB2, etc., performs stream allocation control and cooperative beamforming control on the slave units RU1 to RU3.

[0042] The stream allocation control stores and manages (updates) slave unit information including the capabilities of the slave units RU1 to RU3 (such as the number of streams that can be supported), the number of streams currently allocated, etc., and mobile station information including the position information of the mobile station UE, etc., makes a comprehensive judgment based on this slave unit information and mobile station information, and allocates streams to the slave units RU1 to RU3.

[0043] The coordinated beamforming control manages the usage status (availability status) of radio resources for each of the slave units RU1 to RU3, and controls multiple slave units to perform beamforming in cooperation with respect to a mobile station UE located at a location where the coverage areas of the slave units RU1 to RU3 overlap, according to the usage status of the radio resources.

[0044] More specifically, for example, when the mobile station UE is located at a location where the coverage area of the slave unit RU1 overlaps with the coverage area of the slave unit RU2, and there is a surplus of radio resources in both slave units RU1 and RU2, the slave unit RU1 and the slave unit RU2 perform beamforming so as to transmit and / or receive with respect to the mobile station UE, respectively.

[0045] On the other hand, for example, when the mobile station UE is located at a location where the coverage area of the slave unit RU1 overlaps with the coverage area of the slave unit RU2, and there is no surplus of radio resources in the slave unit RU1, the slave unit RU2 performs beamforming so as to transmit and / or receive with respect to the mobile station UE.

[0046] The storage unit 140 stores a control program and control data used by the control unit 100, and also stores slave unit beam ID map data 140a and the like. The above control program and the above control data are installed in advance at the time of manufacture, and are also installed or updated through an external interface (not shown) at the time of custom order setting, or are installed or updated by communicating with a server on the 5G core network 5GC such as the core device C.

[0047] The slave unit beam ID map data 140a is data used in the coordinated beamforming control, and is a data table that summarizes the beam ID map data 240a stored by each of the slave units RU1 to RU3 under the master unit MU. Details of the beam ID map data 240a will be described later.

[0048] Specifically, the slave unit beam ID map data 140a is map-shaped data in which beam IDs are associated with coordinates indicating the directions of the beams that can be formed by the slave units RU1 to RU3 respectively. Among the beam directions included in this data, for the beam directions in the overlapping area of the coverage areas among the slave units RU1 to RU3 (the area where the beams overlap among the slave units), identification information (for example, an overlap flag) for identifying them as the beam directions of the overlap area OA is assigned.

[0049] Next, the slave units RU1 to RU3 will be described in detail. FIG. 3 shows a configuration example of the slave unit RUn (RU1 to RU3). That is, the slave unit RUn includes a control unit 200, a communication unit 210, a signal processing unit 220, a wireless communication unit 230, and a storage unit 240, and an antenna ANn is connected thereto.

[0050] The communication unit 210 transmits and receives optical communication signals to and from the master unit MU through an optical communication line, includes at least two ports for accommodation, amplifies the optical communication signals input through the optical communication line accommodated in one port, and outputs them through the optical communication line accommodated in the other port, and has a relay function as an optical communication repeater, a branching and multiplexing function for branching and multiplexing optical communication signals with respect to the optical communication line, a modulation / demodulation function as a modulator / demodulator for mutually converting between optical signals and electrical signals, and the like.

[0051] Note that as the modulator / demodulator, it has an optical / electrical conversion function of receiving an optical signal through an optical communication line, performing optical / electrical conversion to obtain an electrical communication signal (DL stream signal), and an electrical / optical conversion function of performing electrical / optical conversion on an electrical communication signal (UL stream signal) input from the signal processing unit 220 described later into an optical communication signal and transmitting it through the optical communication line.

[0052] The signal processing unit 220 communicates with the base station device gNB2 according to a predetermined communication protocol. In the downlink direction (from the base station device to the slave unit) of the system, it demodulates and decodes the communication signals obtained by the communication unit 210, detects the DL stream signal destined for the slave unit RUn based on the identification information for identifying the destination, and outputs it to the control unit 200.

[0053] On the other hand, regarding the upstream direction of the system, a UL stream signal is generated by using the signal addressed to the base station apparatus gNB2 given from the control unit 200 for modulation of a carrier wave, and is output to the communication unit 210. Note that identification information of a transmission source (any one of the slave units RU1 to RU3) is added to the UL stream signal by the signal processing unit 220 or the control unit 200.

[0054] The wireless communication unit 230 performs wireless communication with the mobile station UE through the antenna ANn, and as a wireless access method, a method compliant with 5G is adopted. For this reason, even when the mobile station UE communicates through the distributed antenna system DAS, wireless communication can be performed by the same wireless access method as in the case of communicating with the base station apparatus gNB1 through the antenna AN shown in FIG. 1.

[0055] Further, the wireless communication unit 230 performs beamforming by massive MIMO that controls the phases of signals (transmission RF signals and / or reception RF signals) in a large number of antenna elements on the antenna ANn according to an instruction from the control unit 200.

[0056] Furthermore, the wireless communication unit 230 measures the reception signal strength (for example, RSSI) from the mobile station UE, associates this measurement result with the identification information of the mobile station UE, and notifies the control unit 200. Also, since the frequency bands used are different for each communication carrier, the reception signal strength is detected for each of the above frequency bands, that is, for each communication carrier, and the detection result is notified to the control unit 200.

[0057] The reception signal strength for each communication carrier in the wireless communication unit 230 can be detected with a configuration as shown in FIG. 4 for example. In FIG. 4, configurations related to transmission and reception of wireless signals and modulation / demodulation are omitted, and a configuration for detecting the reception signal strength for each communication carrier as described above is shown.

[0058] As a configuration for this detection, the wireless communication unit 230 includes a signal control unit 231, an output switch (SW) 232, a downlink hybrid circuit 233, a transmission amplifier 234, a circulator 235, a reception amplifier 236, an uplink hybrid circuit 237, a band-pass filter 238, and an RSSI detection unit 239.

[0059] The signal control unit 231 divides the downlink radio frequency signal for each frequency band used by each communication carrier and outputs it to the output switch 232. The output switch 232 includes output switches for each communication carrier, and the ON / OFF of the output switch is controlled by the signal control unit 231. Thus, signals can be selectively output for each communication carrier (frequency band).

[0060] The downlink hybrid circuit 233 combines the signals input from the output switch 232 into one radio frequency signal and outputs it to the transmission amplifier 234.

[0061] The transmission amplifier 234 high-frequency amplifies the radio frequency signal input from the downlink hybrid circuit 233 and outputs it to the antenna ANn with respect to the circulator 235. From the antenna ANn, the above signal is radiated into space and transmitted toward the mobile station UE.

[0062] On the other hand, the radio signal transmitted from the mobile station UE is received by the antenna ANn and then output to the reception amplifier 236 via the circulator 235. The reception amplifier 236 high-frequency amplifies the radio frequency signal received by the antenna ANn from the mobile station UE and outputs it to the uplink hybrid circuit 237.

[0063] The uplink hybrid circuit 237 distributes the signals input from the reception amplifier 236 by the number of communication carriers and outputs them to the band-pass filter 238.

[0064] The band-pass filter 238 includes band-pass filters for each frequency band used by the communication carrier, and each filter outputs only the signal of the frequency band used by the corresponding communication carrier.

[0065] The RSSI detection unit 239 detects the reception intensity (RSSI) for the frequency bands of each communication carrier and notifies the detection result to the control unit 200. Upon receiving the notification, the control unit 200 issues a notification to the signal control unit 231 to specify the communication carrier that performs signal output. According to this specification, the signal control unit 231 controls the output switch 232 to be turned on / off so that only the radio signal of the specified communication carrier is output.

[0066] Returning to FIG. 3 again, the configuration of the slave unit RUn will be described. The control unit 200 is a control center that comprehensively controls each part of the slave unit RUn, and includes a work memory (not shown) and a processor (not shown) that executes processing based on a control program and control data read from the storage unit 240 (to be described later) into the work memory, and realizes various control functions through these. Note that the control unit 200 is an example of a carrier detection unit and a standing wave control unit.

[0067] As specific control functions, in addition to the communication control function for connecting the mobile station UE wirelessly connected to the slave unit RUn to the 5G core network 5GC via the master unit MU and the base station device gNB2, the control unit 200 includes at least a beamforming control function 200a, a search control function 200b, and a cooperation control function 200c, and also includes a processing function for integrating and executing these functions.

[0068] The communication control function detects the communication carrier for the downlink communication signal sent from the base station device gNB2 through the communication unit 210 and the signal processing unit 220, and controls the wireless communication unit 230 to transmit the communication signal in the frequency band of the communication carrier.

[0069] Also, the communication control function detects the communication carrier for the uplink signal received by the wireless communication unit 230 from the mobile station UE, and controls the signal processing unit 220 and the communication unit 210 to transmit the communication signal received from the mobile station UE to the base station device gNB2 of the communication carrier.

[0070] The beamforming control function 200a controls the massive MIMO by the wireless communication unit 230, varies the direction, distance, and beam width of the beam based on the beam ID map data 240a described later, and performs beamforming according to a predetermined algorithm according to, for example, the number of streams assigned to the mobile station UE.

[0071] Regarding the direction, distance, and beam width of the beam, for example, the beamforming control function 200a performs control as shown in FIG. 5. That is, the beamforming control function 200a can selectively form a sharp narrow beam NB with a narrow beam width and a wide beam WB with a wide beam width in an arbitrary direction and distance as needed.

[0072] FIG. 5 shows the formation position (direction) of the beam formed by the beamforming control function 200a. In this example, the coverage area of the slave unit RUn is defined in the x-y plane, and the beamforming control function 200a performs beam control so as to form a narrow beam NB(x, y) with a narrow beam width toward the preset coordinates (x, y). Also, the beamforming control function 200a can perform beam control so as to form a wide beam WBm (m is any one of 1 to 4) with a wide beam width toward each of the four quadrants of the x-y plane.

[0073] Regarding the assignment of the number of streams to the mobile station UE, for example, the beamforming control function 200a performs control as shown in FIG. 6. That is, as shown in FIG. 6(a), for example, the beamforming control function 200a divides a large number of antenna elements on the antenna ANn into four groups Gr1 to Gr4 corresponding to four streams, and controls the directivity in an arbitrary direction for each group.

[0074] When one mobile station UE exists within the coverage area of antenna ANn and two streams are allocated to the mobile station UE, for example, as shown in Fig. 6(b), beamforming is performed to direct the stream by group Gr1 and the stream by group Gr2 in the direction where the mobile station UE exists.

[0075] Also, when one mobile station UE exists within the coverage area of antenna ANn and four streams are allocated to the mobile station UE, for example, as shown in Fig. 6(c), beamforming is performed to direct each stream by groups Gr1 to Gr4 in the direction where the mobile station UE exists.

[0076] The search control function 200b controls the wireless communication unit 230 to search for and estimate (detect) the direction and distance where the mobile station UE exists. Specifically, by controlling the massive MIMO by the wireless communication unit 230, for example, as shown in Fig. 7(a), the direction in which the beam is directed is repeatedly swept in an arbitrary range every 20 ms, and during this period, the received signal strength sequentially detected by the wireless communication unit 230 is monitored to detect the direction and distance where the mobile station UE exists. Fig. 7(b) shows the timing of each beam shown in Fig. 7(a), and the correspondence between the direction and timing is shown by the coincidence of the shading in both figures.

[0077] More specifically, the control unit 200 in the search control function 200b can switch between high-speed search, low-speed search, and tracking search to search for the mobile station UE.

[0078] In the high-speed search, for example, as shown in Fig. 8(a), the variable range of the direction in which the beam is directed (for example, the horizontal direction) is set to about 120°, and as shown in Fig. 8(b), it is repeatedly swept every 20 ms, and during this period, the received signal strength sequentially detected by the wireless communication unit 230 is monitored to detect the identification information of the mobile station UE and the direction and distance where the mobile station UE exists.

[0079] Also, this high-speed search is independently performed for each of the four groups Gr1 to Gr4 of antenna elements on the antenna ANn. The directions searched by each of the groups Gr1 to Gr4 can be arbitrarily set by the operator at the time of work order setting, or the search control function 200b can set or update the settings by looking them up based on the statistical data or learning data of the position information of the mobile station UE that is cumulatively stored in the storage unit 240.

[0080] In the low-speed search, for example, as shown in FIG. 9(a), the variable range of the direction (for example, the horizontal direction) in which the beam is directed is set to about 90°, which is narrower than about 120° during the above-mentioned high-speed search. As shown in FIG. 9(b), it is repeatedly swept every 20 ms. During this period, the reception signal strength sequentially detected by the wireless communication unit 230 is monitored at the same frequency as in the high-speed search, and the identification information of the mobile station UE and the direction and distance where the mobile station UE exists are detected more accurately.

[0081] Also, this low-speed search is independently performed for each of the four groups Gr1 to Gr4 of antenna elements on the antenna ANn. The directions searched by each of the groups Gr1 to Gr4 are centered on the direction detected in the above-mentioned high-speed search. Note that the range of the search direction can be limited by the operator at the time of work order setting, or the search control function 200b can limit it by itself or update the limited range based on the statistical data or learning data of the position information of the mobile station UE that is cumulatively stored in the storage unit 240.

[0082] In the tracking search, for example, as shown in FIG. 10(a), the variable range of the direction (for example, the horizontal direction) in which the beam is directed is set to a trackable range (about 45° in the example of FIG. 10(a)), which is narrower than about 90° during the above-mentioned low-speed search. As shown in FIG. 10(b), it is repeatedly swept every 20 ms. During this period, the reception signal strength sequentially detected by the wireless communication unit 230 is monitored, and the identification information of the mobile station UE and the direction and distance where the mobile station UE exists are detected even more accurately.

[0083] Here, for example, as shown in FIG. 11(a), when the mobile station UE moves, the control unit 200 can estimate the moving direction of the mobile station UE because it can understand the received signal strength of each beam, the magnitude relationship of the received signal strengths in each direction, and the changes thereof, as shown in FIG. 11(b). According to this estimation result, the directivity of the beam is variably controlled so as to follow the mobile station UE.

[0084] Note that the followable range may be variable based on the data learned by the control unit 200 about the movement of the mobile station UE. Also, the distance between the slave unit RUn and the mobile station UE may be estimated from the received signal strength, and the variable range may be varied accordingly. In this case, when the received signal strength is relatively high, it is determined that the distance between the slave unit RUn and the mobile station UE is close, and the variable range is widened. On the other hand, when the received signal strength is relatively low, it is determined that the distance between the slave unit RUn and the mobile station UE is far, and the variable range is narrowed.

[0085] Also, as shown in FIG. 12(a) for example, the search control function 200b can search for two groups Gr1 and Gr2 in the directions set for them even when there are a plurality of mobile stations UE1 and UE2 in substantially the same direction with respect to the antenna ANn.

[0086] In this case, the change in the received signal strength of the mobile station UE1 by the group Gr1 is as shown in FIG. 12(b), and the change in the received signal strength of the mobile station UE2 by the group Gr2 is as shown in FIG. 12(c).

[0087] Also in this case, since the two groups Gr1 and Gr2 are independently controlled by the control unit 200, for example, as shown in FIG. 13(a), when the group Gr1 is performing a low-speed search for tracking the mobile station UE1, the group Gr2 can perform a high-speed search for the mobile station UE2.

[0088] In this case, the change in the received signal strength of the mobile station UE1 by the group Gr1 is as shown in Fig. 13(b), while the change in the received signal strength of the mobile station UE2 by the group Gr2 is as shown in Fig. 13(c).

[0089] The search control function 200b can also search for two or more mobile stations with one group of antenna elements. Specifically, for example, as shown in Fig. 14(a), the group Gr1 on the antenna ANn searches for two mobile stations UE1 and UE2. In this case, as shown in Fig. 14(b), since two peaks appear in the received signal strength, the control unit 200 can detect the number of mobile stations present and their directions by detecting the peaks of the received signal strength.

[0090] The cooperative control function 200c is a control function that performs beamforming in cooperation with other child devices RUm whose coverage areas overlap according to an instruction from the master device MU. This control function also includes a function of controlling the frequency band for transmission by the radio communication unit 230 based on the received signal strength for each telecommunications carrier notified from the radio communication unit 230. Details will be described later.

[0091] The storage unit 240 stores the control programs and control data used by the control unit 200, and also stores beam ID map data 240a and the like. The above control programs and control data are pre-installed at the time of manufacture, and are also installed or updated through an external interface (not shown) at the time of factory order setting, or are installed or updated by communicating with a server on the 5G core network 5GC such as the core device C.

[0092] The beam ID map data 240a is map data of the beam pointing directions obtained by dividing the coverage area of the slave unit RUn for each beam pointing direction as shown in FIG. 5, for example, and assigning a beam ID to each division. More specifically, the coverage area is defined and divided in the x-y plane, the beam ID of the narrow beam pointing to each division is NB(x, y), the beam ID of the wide beam pointing to each quadrant is WBm, and the data is such that the beam pointing directions are preset.

[0093] Also, the slave units RU1 to RU3 are arranged such that a part of their coverage areas overlap with each other, and there is an overlap area OA as this overlapping part. It is possible to direct beams to spatially the same position between the slave units, and each of the slave units RU1 to RU3 sets the above beam ID.

[0094] Therefore, the slave unit beam ID map data 140a stored in the memory unit 140 of the master unit MU is a data table that summarizes the above beam ID map data 240a of the slave units RU1 to RU3 under its control, and for the beam IDs in the overlap area OA, identification information (for example, an overlap flag) indicating that it is the beam direction of the overlap area OA is assigned.

[0095] Next, the operation of the communication relay system will be described. First, the slave unit beam forming process in the slave unit RUn will be described. FIG. 15 is a flowchart for explaining the control flow of the above slave unit beam forming process.

[0096] When the operation of the communication relay system is started, in the slave unit RUn, the control unit 200 executes several control flows in parallel, and one of them is the control flow shown in FIG. 15. The control flow shown in FIG. 15 is repeatedly executed until the operation of the slave unit RUn is stopped or a stop command is given to the slave unit RUn from the master unit MU or the like.

[0097] First, in step S1501, the control unit 200 controls the wireless communication unit 230 by the search control function 200b to estimate (detect) the position where the mobile station UE exists, and detects the communication carrier to which the user of this mobile station UE subscribes from its received signal, and then proceeds to step S1502.

[0098] Specifically, the search control function 200b controls the wireless communication unit 230 to detect the received signal strength while changing the beam pointing direction, search for the direction and distance where the mobile station UE exists, and based on the beam ID map data 240a, detect the beam ID corresponding to the direction and distance where the mobile station UE is found as the position of the mobile station UE.

[0099] In step S1502, the control unit 200 detects the communication carrier to which the mobile station UE existing within the coverage area of the slave unit RUn subscribes, and then proceeds to step S1503.

[0100] Specifically, the cooperation control function 200c controls the wireless communication unit 230 to detect the received signal strength for each communication carrier's frequency band. Then, for the frequency band where this detection result is equal to or greater than the threshold value, it is determined as the communication carrier where the user (mobile station UE) is located, while in the case where it is less than the threshold value, it is determined that there is no user as the communication carrier.

[0101] Note that the detection of the communication carrier in step S1502 may be performed based on the mobile station UE detected in step S1501. That is, based on the signal received from the mobile station UE detected in step S1501, the communication carrier of the service to which this mobile station UE subscribes may be specified.

[0102] In step S1503, the control unit 200, by the cooperation control function 200c, based on the detection result of step S1502, determines whether there is a communication carrier within the coverage area of the slave unit RUn among the communication carriers that the slave unit RUn can relay and where there is no user.

[0103] Here, if there is a communication carrier without users, the process proceeds to step S1504. On the other hand, if there is no communication carrier without users (i.e., all communication carriers have users), the process proceeds to step S1505.

[0104] In step S1504, the control unit 200 controls the wireless communication unit 230 via the cooperative control function 200c so that a downlink radio signal is transmitted only for the communication carriers with users, and then proceeds to step S1505.

[0105] More specifically, the cooperative control function 200c notifies the signal control unit 231 within the wireless communication unit 230 of the communication carriers with users. As a result, the signal control unit 231 controls the switch within the output switch 232 to turn on so as to output only the radio signal in the frequency band corresponding to the notified communication carrier to the downlink hybrid circuit 233. For this reason, the radio signals in the frequency bands corresponding to the communication carriers not notified from the control unit 200 will be silenced.

[0106] In step S1505, the control unit 200 reports, via the cooperative control function 200c, the position (beam ID) of the mobile station UE detected in step S1501 and the identification information (carrier ID) of the communication carrier to which this mobile station UE subscribes to the master unit MU, and then proceeds to step S1506.

[0107] In step S1506, the control unit 200 receives an instruction regarding beamforming from the master unit MU via the cooperative control function 200c, and then proceeds to step S1507. This instruction can be given based on the information reported to the master unit MU in step S1505 and includes the beam ID and the carrier ID.

[0108] In step S1507, the control unit 200 controls the wireless communication unit 230 via the beamforming control function 200a to perform beamforming with respect to the direction, distance, and frequency band of the communication carrier according to the instruction (beam ID and carrier ID) received in step S1506, and then proceeds to step S1501.

[0109] That is, according to the slave unit beamforming process as described above, for example, as shown in FIG. 16, when mobile stations UE1 to UE3 of users of different communication carriers exist in the respective coverage areas of slave units RU1 to RU3, each of the slave units RU1 to RU3 transmits a radio signal only for the frequency band of the communication carrier where the user is located.

[0110] Therefore, as a system, power consumption can be saved in each of the slave units RU1 to RU3, and for the mobile station UE, the influence of other radio signals can be suppressed and an improvement in communication quality can be expected. In particular, in a position where the coverage areas overlap between the slave units RU1 to RU3 or when the slave units are close to each other, an even greater improvement in communication quality can be expected compared to the prior art.

[0111] Next, the master unit beamforming process in the master unit MU will be described. FIG. 17 is a flowchart for explaining the control flow of the master unit beamforming process.

[0112] When the operation of the communication relay system is started, in the master unit MU, the control unit 100 executes several control flows in parallel, one of which is the control flow shown in FIG. 17. The control flow shown in FIG. 17 is repeatedly executed until the operation of the master unit MU is stopped or a stop command is issued to the master unit MU from the core device C or the like.

[0113] First, in step S1701, the control unit 100 receives a report from the slave unit RUn in step S1505, that is, a report on the position (beam ID) of the mobile station UE and the identification information (carrier ID) of the communication carrier in the coverage area of the slave unit RUn, and proceeds to step S1702.

[0114] In step S1702, based on the slave device beam ID map data 140a, the control unit 100 analyzes (determines) whether the position (beam ID) of the mobile station UE received in step S1701 is included in the coverage area of another slave device, that is, whether the position of the mobile station UE based on the beam ID is a position (overlap area OA) that overlaps with the coverage area of another slave device, and then proceeds to step S1703. Note that it can be determined based on whether a superimposed flag is assigned to the beam ID.

[0115] In step S1703, when the control unit 100 determines based on the analysis result of step S1702 that the mobile station UE exists in the overlap area OA, for each of the slave device RUn and the other slave device, it detects the availability status (e.g., the number of available ones) of the radio resources of the communication carrier reported in step S1701, analyzes (or determines) whether there is a margin, and then proceeds to step S1704.

[0116] Note that the radio resources mentioned here may include resource blocks in OFDM communication, the number of beams that can be formed by the slave device RUn, antenna elements for forming beams, etc. Also, although it is described as radio resources here, more broadly, it may be communication resources. This communication resource includes not only the above-mentioned radio resources but also resources related to communication using an optical communication line between the master device MU, that is, the definition of the communication resource includes the scope understood by those skilled in the communication field.

[0117] In step S1704, based on the analysis result of step S1703, when there is a margin of radio resources for each of the slave device RUn and the other slave device, the control unit 100 generates an instruction including directing the beams of the slave device RUn and the other slave device to the above positions and allocating radio resources to the mobile station UE existing in the overlap area OA, and then proceeds to step S1705.

[0118] On the other hand, if there is no margin in radio resources for either the slave unit RUn or the other slave unit, at least one slave unit with a margin in radio resources among the slave unit RUn and the other slave unit generates an instruction including directing a beam to the overlap area OA and allocating radio resources, and proceeds to step S1705.

[0119] When a plurality of slave units communicate with the mobile station UE respectively, for the downlink, each slave unit may transmit different streams from each other to improve the transmission rate, or each slave unit may transmit the same stream from each other to increase the combined power in the mobile station UE and improve the communication stability. These controls are performed by the control unit 100 of the master unit MU.

[0120] In step S1705, the control unit 100 transmits the instruction generated in step S1704 to the corresponding slave unit and proceeds to step S1701. The instruction includes at least a beam ID for indicating the direction of the beam and identification information (carrier ID) of the carrier for indicating the frequency band. The instruction sent here is received by the slave unit in step S1506 and the like described above.

[0121] That is, according to the master unit beamforming process as described above, for example, as shown in FIG. 18, when the mobile station UE exists in the overlap area OA where the coverage areas of the slave units RU1 and RU2 overlap, if there is a margin in radio resources, the slave units RU1 and RU2 form beams and communicate with the mobile station UE existing in the overlap area OA according to the instruction of the master unit MU.

[0122] On the other hand, when the mobile station UE exists in the overlap area OA where the coverage areas of the slave units RU1 and RU2 overlap as in FIG. 18 and there is no margin in radio resources, as shown in FIG. 19, the slave units RU1 and RU2 form beams and communicate with the mobile station UE existing in the overlap area OA by only one slave unit (the slave unit RU2 in FIG. 19) according to the instruction of the master unit MU.

[0123] In summary, in the communication relay system with the above configuration, for each of the slave units RU1 to RU3, the communication carrier to which the mobile station UE existing in the coverage area subscribes is detected, and for the communication carrier in which the mobile station UE does not exist, the radio signal in that frequency band is not transmitted.

[0124] Therefore, according to the communication relay system with the above configuration, since the slave unit RUn does not transmit unnecessary radio signals, the power consumption of the system can be suppressed, and the transmission of radio signals that may affect the coverage area of the mobile station UE of other communication carriers and other slave units is suppressed, and an improvement in communication quality can be expected.

[0125] Further, in the communication relay system with the above configuration, when a mobile station UE exists in an overlap area OA where the coverage areas overlap among a plurality of slave units, resource allocation for cooperative communication can be performed among the plurality of slave units under the control of the master unit MU. For this reason, improvement of the coverage area and improvement of the capacity can be expected.

[0126] Note that the present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof. Further, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiment. Also, for example, a configuration in which some components are deleted from all the components shown in the embodiment is also conceivable. Furthermore, components described in different embodiments may be appropriately combined.

[0127] For example, in the above embodiment, the case where the slave unit RUn makes a determination to prevent transmission of a radio signal in the frequency band of a communication carrier without a user has been described as an example, but the control unit 100 of the master unit MU may make the determination. That is, the control unit of the master unit MU may function as a carrier detection unit and a squelch control unit.

[0128] Needless to say, various modifications can be made without departing from the gist of the present invention, and the invention can be similarly implemented.

Description of Symbols

[0129] 5GC…G Core Network, 100…Control Unit, 110…Transmission Unit, 120…UL Signal Processing Unit, 130…DL Signal Processing Unit, 140…Memory Unit, 140a…Slave Unit Beam ID Map Data, 200…Control Unit, 200a…Beamforming Control Function, 200b…Search Control Function, 200c…Cooperation Control Function, 210…Communication Unit, 220…Signal Processing Unit, 230…Wireless Communication Unit, 231…Signal Control Unit, 232…Output Switch, 233…Downlink Hybrid Circuit, 234…Transmission Amplifier, 235…Circulator, 236…Receiving Amplifier, 237…Uplink Hybrid Circuit, 238…Bandpass Filter, 239…RSSI Detection Unit, 240…Memory Unit, 240a…Beam ID Map Data, AN…Antenna Device, AN1~AN3…Antennas, EN…External Telephone Network, Gr1~Gr4…Groups, Gr1…Group, Gr2…Group, IN…Internet, MU…Master Unit, NR…Radio Access Network, P…Port, RU1~RU3…Slave Units, UE1~UE3…Mobile Stations, gNB1, gNB2…Base Station Devices.

Claims

1. For transmitting a radio signal related to wireless communication between a base station and a mobile station, a communication relay system having a master unit capable of transmitting and receiving signals with the base station, and a plurality of slave units capable of transmitting signals with the master unit and performing wireless communication with the mobile station, a detection unit configured to detect the presence of the mobile station at a position where wireless communication with the plurality of slave units is possible; a determination unit configured to determine which of the plurality of slave units to allocate communication resources for performing wireless communication with the mobile station present at the position where wireless communication is possible; an allocation unit configured to allocate communication resources to the slave unit according to the determination result of the determination unit; a carrier detection unit configured to detect a communication carrier of the service to which the mobile station subscribes; a squelch control unit configured to control so that the slave unit does not transmit the radio signal in a frequency band used by a communication carrier other than the communication carrier detected by the carrier detection unit A communication relay system comprising.

2. Furthermore, a resource detection unit configured to detect the availability status of communication resources of the plurality of slave units is provided, The determination unit determines which of the plurality of slave units to allocate communication resources for performing wireless communication with the mobile station present at the position where wireless communication is possible according to the detection result of the resource detection unit. The communication relay system according to claim 1.

3. The determination unit makes a determination to allocate communication resources for performing wireless communication with the mobile station present at the position where wireless communication is possible to any one of the plurality of slave units according to the detection result of the resource detection unit. The communication relay system according to claim 2.

4. A communication relay system having a plurality of slave units and a master unit that transmit signals related to communication between a base station and a mobile station related to a plurality of communication carriers and transmit the radio signal related to the communication to the mobile station, a carrier detection unit configured to detect a communication carrier of the service to which the mobile station subscribes; a squelch control unit configured to control so that the slave unit does not transmit the radio signal in a frequency band used by a communication carrier other than the communication carrier detected by the carrier detection unit A communication relay system comprising.

5. A wireless device that transmits signals between a master unit capable of transmitting and receiving signals with a base station related to a plurality of communication carriers and transmits a radio signal to a mobile station, a carrier detection unit configured to detect a communication carrier of the service to which the mobile station subscribes; A radio device comprising a stop wave control unit that controls so as not to transmit a radio signal in a frequency band used by a communication carrier other than the communication carrier detected by the above-described carrier detector and a radio device including the same.

Images