Terminal station, communication system, and communication method

Abstract

To provide a terminal station capable of reducing the overhead, i.e, a communication traffic required for reporting in beam management, which controls the beam direction, depending on the location of the moving terminal station and reception conditions.SOLUTION: A terminal station receives a radio signal via multiple beams transmitted under the control of the network control unit and measures the received signal. The terminal station determines whether to notify the control device of reporting of the measured received signal based on the measurement results of the received signal. When determining to issue a notification on the reporting, the terminal station notifies the control device of the reporting.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] In wireless access networks beyond 5G, it is required to control the beam direction according to the location and reception conditions of mobile terminal stations. This control is also called beam management. In a wireless access network, the beam management procedure for a base station to obtain an appropriate beam is, for example, as follows: The terminal station performs measurements using measurement resources and transmits a measurement report to the base station. After receiving this measurement report, the base station applies a more appropriate beam based on the measurement report. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] “MIMO enhancements in Rel19”, RWS-230207 3GPP TSG RAN Rel 19 Workshop June 15-16, 2023 [Non-patent document 2] “Enhancements for Event-driven Beam Management”,R1-2400381 3GPP TSG RAN WG1 #116 February 26th - March 1st, 2024 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, the terminal station periodically reports the reception status, which poses a problem of increased communication traffic, ie, overhead, required for reporting.

[0005] An aspect of the disclosed embodiment is to reduce communication traffic, i.e., overhead, required for reporting in beam management that controls the direction of a beam depending on the position and reception conditions of a moving terminal station. [Means for solving the problem]

[0006] One aspect of the disclosed embodiment is exemplified by a terminal station. The terminal station receives radio signals from multiple beams transmitted under control of a network control device and measures the received signals. The terminal station then determines whether to report the measured received signals to the control device based on the measurement results of the received signals. If it is determined that a report should be sent, the terminal station sends the report to the control device. [Effects of the Invention]

[0007] This control device can reduce communication traffic required for reporting, that is, overhead, in beam management for controlling the direction of a beam. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating the use of beamforming in a mobile communication environment. [Figure 2] FIG. 2 is a diagram illustrating a beam management procedure between a base station and a terminal station. [Figure 3] FIG. 3 is a diagram illustrating a communication system according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating another example of a communication system included in an embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of a hardware configuration of the control device. [Figure 6] FIG. 6 is a sequence diagram illustrating a beam management process of a comparative example. [Figure 7] FIG. 7 is a sequence diagram illustrating a beam management process between a control device and a terminal station according to an embodiment. [Figure 8]FIG. 8 is a flowchart that embodies the processing of a terminal station in the beam management processing of one embodiment. [Figure 9] FIG. 9 is a diagram illustrating received signal power St,i and received signal power St+1,i. [Figure 10] FIG. 10 is a diagram illustrating a single threshold for received signal power St,i or SINR. [Figure 11] FIG. 11 is a flowchart illustrating a process A for determining a threshold for the received signal power St,i or SINR. [Figure 12] FIG. 12 is a diagram illustrating a plurality of thresholds ThA and ThB for the received signal power St,i or SINR. [Figure 13] FIG. 13 is a flowchart illustrating a determination process B using two thresholds ThA and ThB for the received signal power St,i or SINR. [Figure 14] FIG. 14 is a diagram illustrating a threshold determination process for the difference between the previous measurement result and the current measurement result. [Figure 15] FIG. 15 is a diagram illustrating details of the reporting process after determining whether or not it is necessary, and the beam change request process. [Figure 16] FIG. 16 is a diagram illustrating another method of the details of the reporting process after determining whether or not it is necessary and the process of requesting a beam change. [Figure 17] FIG. 17 is a diagram illustrating another method of the details of the reporting process after determining whether or not it is necessary and the process of requesting a beam change. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a terminal station 4, communication systems 100A and 100B, and a communication method according to an embodiment will be described with reference to the drawings. The terminal station 4 receives radio signals from multiple beams transmitted from a base station 2 under the control of a control device 1 in a network N1, and measures the received signals. The terminal station 4 then determines whether to report the measured received signals to the control device 1 based on the measurement results of the received signals. Furthermore, if it is determined that the terminal station 4 should report the measured received signals, it notifies the control device 1 of the report.

[0010] Here, the control device 1 may be built into the base station 2. Alternatively, the control device 1 may cooperate with the base station 2 through a communication carrier network called a core network. In either case, the control device 1 and the base station 2 constitute a control system and provide a wireless access network to the terminal station 4.

[0011] The terminal station 4 does not simply notify the control system of a report of the measured received signal, but notifies the control system of this report when it is decided to notify the report. Therefore, the terminal station 4 can reduce communication traffic or overhead caused by notifying the report. The terminal station 4 includes a controller that executes the above communication method.

[0012] <Embodiment> The terminal station 4, the communication systems 100A and 100B, and the communication method will be described below with reference to FIGS.

[0013] (Application example) 1 and 2, application examples of the terminal station 4, communication systems 100A and 100B, and communication methods will be described. FIG. 1 is a diagram illustrating the use of beamforming in a mobile communication environment. FIG. 1 illustrates a vehicle 50 traveling on a road R1. The vehicle 50 includes a terminal A station 4 (referred to as UE) is installed. UE is an abbreviation for User Equipment. The UE may be, for example, what is called an in-vehicle device.

[0014] In addition, for example, base stations 2-1 to 2-4 are located in the area in which the vehicle 50 travels. The base stations 2-1 to 2-4 are collectively referred to as base stations 2. Note that the number of base stations 2 is not limited to four.

[0015] The base stations 2 are connected to the control device 1 through a network N1. The network N1 includes a communications carrier network known as a core network and public networks such as the Internet. The base stations 2 are equipped with antennas capable of controlling the radiation pattern of the radio signals (electromagnetic waves) they transmit (see Figures 3 and 4). Using multiple antenna elements, the antenna elements can be controlled to have high gain (antenna gain) in a specific direction. The resulting directional radiation pattern is called a beam. The control device 1 can control the direction of the beam from each base station 2.

[0016] As described above, vehicle 50 travels on road R1. Terminal station 4 mounted on vehicle 50 moves on road R1 as vehicle 50 moves. Meanwhile, base station 2 transmits radio signals using beams that propagate in a specific direction. Therefore, in order to maintain good wireless communication between base station 2 and terminal station 4, it is desirable for base stations 2-1 to 2-4 to point the propagation direction of their beams toward the moving vehicle 50. Therefore, control device 1 controls the propagation direction of the beam depending on the position and reception conditions of moving terminal station 4. In FIG. 2, the controlled propagation direction of the beam is illustrated by a dotted arrow. This control is also called beam management.

[0017] 2 illustrates a beam management procedure between the base station 2 and the terminal station 4. The base station 2 has an antenna with an array of antenna elements, and can control the directivity (beam width and propagation direction) of the wireless signals it transmits and receives to scan the transmission beam and reception beam.

[0018] On the other hand, the terminal station 4 has an antenna with a plurality of arranged antenna elements and can form a plurality of receiving beams (#U0 to #Uj) (see FIGS. 3 and 4). In this embodiment, the terminal station 4 is not limited to one having a plurality of antennas, and may be one having an antenna with a single antenna element.

[0019] As shown in Fig. 2, the beam management procedure includes three phases P1 to P3. In phase P1, the base station 2 sweeps a relatively wide transmission beam, for example, transmitting the transmission beam to the entire cell served by the base station 2. At this time, the terminal station 4 sweeps a relatively wide reception beam at the terminal station 4 and receives the transmission beams in multiple directions swept by the base station 2. The terminal station 4 then selects the best received signal (the best transmission beam measured at the best reception beam) from the transmission beams swept in multiple directions and reports it to the base station 2. This determines the initial transmission beam and reception beam.

[0020] However, the receiving beam is swept when the terminal station 4 has an arrangement of multiple antenna elements and supports beamforming. Therefore, when the terminal station 4 does not support beamforming, reception is performed using a single relatively wide receiving beam or an omnidirectional antenna.

[0021] In Phase P2, after the initial transmission beam and reception beam are determined, the base station 2 sweeps the transmission beam narrower than in Phase P1 and performs reception using the best reception beam determined in Phase P1. In other words, the base station 2 refines the beam more than in Phase P1 ( For example, sweep a beam narrower than P1 in a narrower sweep range than P1), transmit beam The reference radio signal (reference signal) is transmitted in phase P2. The range in which the transmission beam is swept is , is determined based on the best transmit beam selected in phase P1.

[0022] The terminal station 4 receives the narrower transmission beam transmitted from the base station 2 with a single fixed reception beam of the same width as in phase P1. The fixed reception beam is the reception beam determined to be the best in phase P1. The terminal station 4 then measures the received signal power of the reference signal from the refined multiple transmission beams and reports the transmission beam with the highest received signal power (best transmission beam) to the base station 2. However, the terminal station 4 uses the highest Signal to Interference plus Noise power Ratio (SINR) instead of the highest received signal power. The received beam may be reported to base station 2.

[0023] In phase P3, the base station 2 locks the beam to the best transmission beam reported by the terminal station 4 in phase P2. That is, the base station 2 repeatedly transmits the best transmission beam. The terminal station 4 sweeps the reception beam more precisely than in P2 and determines the best reception beam. As described above, the reception beam sweep is performed when the terminal station 4 supports beamforming. Furthermore, the best reception beam in phase P3 is determined, for example, by measuring the received signal power of a reference radio signal (reference signal) received from multiple reception beams and determining the reception beam with the highest received signal power or the highest SINR.

[0024] Beam management is also performed when the terminal station 4 is connected to the control device 1 via the base station 2 and is in communication. That is, the terminal station 4 periodically receives reference signals from the base station 2 using multiple beams and measures the received signal power, SINR, etc. The terminal station 4 reports the reception status to the base station 2 or the control device 1 via the base station 2 based on the measured received signal power, SINR, etc. The base station 2 or the control device 1 resets (changes) the beam based on the report from the terminal station 4. For example, the base station 2 or the control device 1 selects a beam with higher received signal power or SINR, etc., instead of a transmission beam currently in use whose received signal power or SINR, etc. has deteriorated, and applies this beam to communication with the terminal station 4.

[0025] (System Configuration) FIG. 3 is a diagram illustrating a communication system 100A of this embodiment. The communication system 100A includes a control device 1, a base station 2, and a terminal station 4. As described above, the control device 1 is a device on a core network to which the base station 2 is connected. However, the control device 1 can also be considered to be the core network itself, or a system included in the core network. The control device 1 controls the base station 2 and the terminal station 4, and provides communication services to the terminal station 4.

[0026] The base station 2 provides a wireless access network to the terminal station 4. An area where wireless communication is possible in the wireless access network is also called a cell. The base station 2 has an antenna capable of forming multiple beams (for example, #B0 to Bi, where i is an integer greater than or equal to 2), a radio 21 connected to these antennas, and a control circuit 22. The antenna forms a transmission beam and a reception beam, which are directional radiation patterns, using the multiple beams (#B0 to Bi). A station capable of transmitting and receiving radio waves is also called a Transmission and Reception Point (TRP). The base station 2 may have multiple TRPs capable of forming multiple beams (#B0 to Bi).

[0027] The radio 21 includes a transceiver for transmitting radio signals and a receiver for receiving radio signals, and is connected to an antenna (forming beams #B0 to #Bi). The control circuit 22 includes, for example, a processor and a memory. The processor controls communication with the control device 1 and radio communication with the terminal station 4 using a computer program stored in the memory.

[0028] The terminal station 4 is also called a mobile station. The terminal station 4 connects to a wireless access network within the range of a cell provided by the base station 2. The terminal station 4 has an antenna (forming beams #U0 to #Uj), a radio device 41 connected to the antenna, and a control circuit 42. The configurations of the radio device 41 and the control circuit 42 are similar to the configurations of the radio device 21 and the control circuit 22 of the base station 2. That is, the control circuit 42 has, for example, a processor and a memory. The processor controls wireless communication with the control device 1 and the base station 2 according to a computer program in the memory.

[0029] FIG. 4 is a diagram illustrating a communication system 100B, another example included in this embodiment. Compared to the communication system 100A of FIG. 3, the communication system 100B has a central base station 2A and one or more distributed base stations 2B instead of the base station 2. When one or more distributed base stations 2B are individually distinguished, they are assigned sub-numbers such as distributed base stations 2B-1, ..., 2B-K. Here, the sub-number K is an integer indicating the number of distributed base stations. Each distributed base station 2B can transmit and receive radio waves using a beam (#B0 to #Bi) instructed by the control device 1. Therefore, the beams that the terminal station 4 measures include not only beams transmitted from an individual distributed base station 2B (e.g., distributed base station 2B-1) but also beams transmitted from multiple distributed base stations 2B-1, ..., 2B-K, etc. In FIG. 4, the distributed base stations 2B-1 and 2B-K are illustrated as examples. However, when the distributed base stations 2B-1, . . . , 2B-K are collectively referred to, they are simply referred to as the distributed base station 2B.

[0030] The central base station 2A has a control circuit 22A. Furthermore, the distributed base station 2B has a radio 21B. The control circuit 22A of the central base station 2A and the radio 21B of the distributed base station 2B are connected by, for example, an optical fiber C1 or a wireless network. There are no limitations on the topology of the optical fiber C1 connecting the central base station 2A and multiple distributed base stations 2B. For example, the topology of the optical fiber C1 may be a one-to-one connection between nodes, a network that branches with increasing distance from the central base station 2A, a star network, or a ring network. Furthermore, when the control circuit 22A of the central base station 2A and the radio 21B of the distributed base station 2B are connected by a wireless network, there are no limitations on the standard or protocol of the wireless network.

[0031] The control circuit 22A has a processor and a memory, similar to the control circuit 22 in Fig. 3. The processor controls communication with the control device 1 and wireless communication with the terminal station 4 using a computer program in the memory. That is, the control circuit 22A controls wireless communication with the terminal station 4 via the radio 21B of one or more distributed base stations 2B.

[0032] 3 and 4, the base station 2 and the distributed base station 2B use at least one of a plurality of antenna elements and a polarization plane to communicate with the terminal station 4 by Multiple-Input and Multiple-Output (MIMO). Note that the configuration of the terminal station 4 in FIG. 4 is the same as that in FIG. 3.

[0033] In this embodiment, the control device 1 is a device on a core network to which the base station 2 is connected. Alternatively, the control device 1 is the core network itself, or a system included in the core network. However, the control device 1 is not limited to such a device on a core network. For example, the control device 1 may be a device included in the base station 2. For example, the control device 1 may be a device provided in the base station 2 and communicating with the terminal station 4 via the radio 21.

[0034] FIG. 5 is a diagram illustrating an example of the hardware configuration of the control device 1. The control device 1 has a CPU 11, a main memory device 12, and external devices, and executes communication processing and information processing by computer programs. The CPU 11 is also called a processor. The CPU 11 is not limited to a single processor, and may be configured as a multi-processor. The CPU 11 also includes a Gr The CPU 11 may include a graphics processing unit (GPU), a digital signal processor (DSP), etc. Also, the CPU 11 may include a field programmable gate array (FPGA), etc. The external device may be one that cooperates with a hardware circuit of the above. Examples of the external device include an external storage device 13, an output device 14, an operation device 15, and a communication device 16.

[0035] The CPU 11 executes a computer program that has been loaded in an executable manner into the main memory device 12, and provides processing for the control device 1. The main memory device 12 stores the computer program executed by the CPU 11, data processed by the CPU 11, etc. The main memory device 12 is a dynamic random access memory (DRAM), a static random access memory (SRAM), a read only memory (ROM), etc. Furthermore, the external memory device 13 is, for example, a memory that stores data stored in the main memory device 1. The external storage device 13 is used as a storage area supporting the CPU 11 and stores computer programs executed by the CPU 11, data processed by the CPU 11, etc. The external storage device 13 is a hard disk drive, a solid state drive (SSD), etc. Furthermore, the control device 1 may include a removable storage medium. A drive of the body may be connected to the removable storage medium, such as a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), a flash memory card, etc.

[0036] The output device 14 is, for example, a display device such as a liquid crystal display or an electroluminescence panel. However, the output device 14 may also include a speaker or other device that outputs sound. The operation device 15 is, for example, a touch panel with a touch sensor superimposed on a display. The communication device 16 communicates with the base station 2 and an external network such as the Internet via, for example, optical fiber. The communication device 16 is, for example, a gateway connected to the base station 2 and a gateway that communicates with an external network such as the Internet. The communication device 16 may be a single device or a combination of multiple devices.

[0037] (Processing procedure for comparative example) 6 is a sequence diagram illustrating a beam management process in a comparative example. In the comparative example, beam management between a control device 301 and a terminal station 304 is illustrated. However, in FIG. 6, at least a part of the processing of the control device 301 may be executed by a base station that provides a cell to the terminal station 304.

[0038] As explained in Fig. 2, beam management is performed even when the terminal station 4 is in communication connected to the control device 1 via the base station 2. That is, the terminal station 4 in Fig. 2 periodically receives reference signals from multiple beams from the base station 2 (TRP) and measures the received signal power or SINR, etc. The terminal station 4 reports the reception status to the base station 2 or the control device 1 via the base station 2 based on the measured received signal power or SINR, etc. The base station 2 or the control device 1 resets or changes and controls the beam based on the report from the terminal station 4. An example of beam management processing according to a comparative example is given below.

[0039] In this process, the control device 301 sets a beam (S301). By setting the beam, for example, the width (directivity) of the transmission beam and reception beam at the base station, the angular range over which the transmission beam and reception beam are swept, the number of times the sweep is repeated, the period for repeating the sweep, etc. are determined. Then, the control device 301 notifies the terminal station 304 of information on the set beam and a communication resource slot (also called a reporting slot) for the terminal station 304 to report the reception status (S302).

[0040] Then, the terminal station 304 applies the beam information received from the control device 301 to its own processing (S303). That is, the terminal station 304 prepares to receive a reference signal from the control device 301. More specifically, the terminal station 304 sets its own receiving beam.

[0041] Next, the control device 301 transmits a data transmission radio signal for transmitting user data using a data transmission beam via the base station (TRP). The data transmission radio signal includes a slot for user data and a slot for a reference radio signal. The control device 301 also allocates a radio signal for beam reception status evaluation to multiple beams, sweeps the beams, and transmits the beams via the base station (TRP) (S304). That is, the beams of the radio signals transmitted from the base station 302 include a beam for transmitting user data and multiple measurement beams transmitted in multiple directions for beam management.

[0042] At least a part of the processing of S304 may be executed by the base station. Then, the terminal station 304 receives radio signals for evaluating beam reception conditions transmitted by beams for data transmission, and measures, for example, the received signal power, SINR, etc. of each beam. The terminal station 304 also receives radio signals for evaluating beam reception conditions assigned to multiple beams, and measures, for example, the received signal power, SINR, etc. of each beam. Then, the terminal station 304 reports the reception conditions based on the measurement results (S305, S306).

[0043] The control device 301 or the base station then determines whether or not a beam change is necessary based on the reception status reported by the terminal station 304 (S307). If a beam change is necessary, the processes from S312 onward are executed. On the other hand, if a beam change is not necessary, the control device 301 or the base station continues processing without changing the beam. That is, the control device 301 or the base station transmits a radio signal for data transmission. The control device 301 or the base station also allocates a radio signal for beam reception status evaluation to multiple beams, sweeps the beams, and transmits the signal again (S308). The terminal station 304 then receives the radio signal for beam reception status evaluation and measures, for example, the received signal power, SINR, etc. of each beam. The terminal station 304 then reports the reception status based on the measurement results (S309, S310).

[0044] Then, the control device 301 or the base station determines whether or not a beam change is necessary based on the reception status reported from the terminal station 4 (S311). If a beam change is not necessary, the processes from S308 onward are executed. On the other hand, if a beam change is necessary, the control device 301 or the base station sets a beam (S312). The process of S312 is the same as the process of S301.

[0045] Here, the comparative example has the following problem. That is, the terminal station 304 reports the reception status of the downlink signal for the assigned beam to the control device 301 at predetermined intervals. In this case, the report is made even when the reception status is good. As a result, due to the reports from the terminal station 4, communication traffic increases, communication resources (frequencies and slots) are consumed, and an increase in overhead is expected. Conversely, even when a sudden change in the communication status occurs (such as in a high-speed moving environment), the control device 301 or the base station will wait for the assigned report timing. As a result, there is a possibility that the communication line will be interrupted.

[0046] (Processing procedure of the embodiment) 7 to 17, processing procedures performed by the control device 1, base station 2, and terminal station 4 of this embodiment are illustrated. In this embodiment, a method is illustrated in which the terminal station 4 reports the reception status in accordance with the possibility of reception status degradation and determines whether a beam change is necessary. In this embodiment, the terminal station 4 notifies the control device 1 of a report of the reception status and a request for beam change when it determines that a beam change is necessary. As a result, the communication systems 100A and 100B of this embodiment solve the problems presented in the comparative example.

[0047] 7 is a sequence diagram illustrating a beam management process between the control device 1 and the terminal station 4 according to this embodiment. Note that, although the beam management process between the control device 1 and the terminal station 4 is illustrated in this embodiment, at least a part of the process of the control device 1 may be executed by the base station 2.

[0048] Of the processes in Fig. 7, the processes from S1 to S4 are the same as S301 to S304 in Fig. 6. That is, the control device 1 allocates reference signals for beam reception status evaluation to multiple beams via the base station 2 (TRP), sweeps the beams, and transmits them (S4). Then, the terminal station 4 receives the reference signals allocated to the multiple beams, and measures, for example, the received signal power, SINR, etc. of each beam (S5). Then, the terminal station 4 determines whether or not a reception status report is required (S6).

[0049] If the determination in S6 indicates that a report is necessary, the terminal station 4 executes the processes from S10 onwards. On the other hand, if the determination in S6 indicates that a report is not necessary, the terminal station 4 does nothing and waits for the next opportunity to receive the reference signal. Then, the control device 1 or base station 2 again assigns, sweeps, and transmits reference signals for beam reception status evaluation to multiple beams (S7). Then, the terminal station 4 receives the reference signals assigned to the multiple beams and measures, for example, the received signal power, SINR, etc. of each beam (S8). Then, the terminal station 4 determines whether or not a reception status report is necessary (S9).

[0050] If the determination in S9 indicates that a report is not required, the terminal station 4 executes the processes from S8 onward. On the other hand, if the determination in S9 indicates that a report is required, the terminal station 4 reports the reception status to the base station 2 or to the control device 1 via the base station 2 (S10, S11).

[0051] Then, the control device 1 or the base station 2 sets, for example, a beam based on the received report (S12). The processing of S12 is the same as S311 and S312 in Fig. 6. Note that the terminal station 4 may report the reception status based on the results of measuring the received signal power, SINR, etc. of each beam, and may also notify the control device 1 via the base station 2 or the base station 2 of a beam change request.

[0052] FIG. 8 is a flowchart that embodies the processing of the terminal station 4 in the beam management processing of this embodiment. This processing is executed during data communication after the transmission beam and the reception beam have been determined, for example, through phases P1 to P3 illustrated in FIG. 2. In this processing, the terminal station 4 first executes processing to acquire determination materials (S20). This processing can also be called measurement processing. That is, the terminal station 4 receives reference signals transmitted by each beam from the control device 1 via the base station 2, and measures the received signal power S,i. Here, t is a subscript indicating the reception timing of the reference signal, for example, the measurement result at the t-th reception. t may also represent the reception time. Furthermore, i is a subscript that identifies each of the multiple beams. i can also be called a beam ID (identifier). Note that the terminal station 4 may measure the SINR for each beam at each time, instead of the received signal power S,i.

[0053] FIG. 9 illustrates received signal power S,i and received signal power S+1,i. In FIG. 9, the diagram above the arrow illustrates received signal power S,i, and the diagram below the arrow illustrates received signal power S+1,i. In addition, the horizontal axis of the two upper and lower diagrams in FIG. 9 is the beam ID that identifies the beam, which corresponds to i. In addition, the vertical axis of the two upper and lower diagrams in FIG. 9 is the received signal power (or SINR) from each beam identified by the beam ID (subscript i). Therefore, FIG. 9 can also be said to be a diagram comparing the measurement result of the t-th received signal strength with the measurement result of the t+1-th received signal strength. In addition, in FIG. 9, the graphs (bars) filled in black illustrate the received signal power S,i and S+1,i of the beams currently being used by base station 2 for data communication with terminal station 4.

[0054] Returning to FIG. 8, the explanation continues. The terminal station 4 may receive the reference signal and measure a change in the orientation of the terminal station 4. If the terminal station 4 is equipped with an azimuth angle sensor or the like, the change in the orientation of the terminal station 4 can be acquired from this sensor. The azimuth angle sensor may include, for example, a magnetic sensor corresponding to three axes (X, Y, and Z axes), and may detect or determine in which direction the terminal station 4 is facing relative to the coordinate axes of the three-dimensional space indicated by the geomagnetism.

[0055] Here, the orientation of the terminal station 4 can also be called its attitude, and is exemplified by the orientation of a reference vector, for example, the normal vector of a surface. The terminal station 4 then determines whether the orientation at the current measurement time t has changed beyond an allowable limit relative to the orientation at the previous measurement time t-1. Here, the allowable limit is a limit to the extent to which the measurement of the received signal power S,i or the SINR is affected, and is a value that can be determined experimentally. Here, the determination of whether the orientation at the current measurement time t has changed beyond an allowable limit relative to the orientation at the previous measurement time t-1 determines whether the orientation has changed between the previous (t-1th) measurement and the current (tth) measurement. This determination is an example of determining whether the orientation of the terminal station 4 in three-dimensional space has changed before, during, or after the process of measuring the received signal.

[0056] Next, the terminal station 4 executes a determination process (S21). For example, the terminal station 4 performs a threshold determination on the received signal power St,i or SINR (see FIGS. 10 and 11). The threshold determination is a determination of the reception situation based on, for example, the presence or absence of a beam whose received signal power St,i or SINR exceeds a threshold, the number of beams, etc. The terminal station 4 may execute the threshold determination using multiple thresholds (see FIGS. 12 and 13).

[0057] Furthermore, the terminal station 4 may perform a threshold determination on the difference between the previous measurement result (received signal power St-1,i) and the current measurement result (received signal power St,i) (see FIG. 14). Furthermore, in addition to the determination processes of S21 above, the terminal station 4 may add a change in the orientation of the terminal station 4 to the determination criteria if the change in the orientation of the terminal station 4 can be detected (see FIGS. 11 and 13).

[0058] Next, the terminal station 4 executes processing based on the determination result (S22). For example, if the reception condition is good, the terminal station 4 does not report the reception condition to the base station 2 or the control device 1 via the base station 2. Also, if the reception condition is good, the terminal station 4 does not notify the base station 2 or the control device 1 via the base station 2 of a beam change request.

[0059] On the other hand, for example, if the reception conditions are not good, the terminal station 4 reports the reception conditions to the base station 2 or to the control device 1 via the base station 2. The contents of the report include, for example, the measurement results of the received signal power S,i for all beams. The contents of the report may also include, for example, the beam ID(i) that exceeds the threshold. The contents of the report may also include, for example, the beam ID(i) that exceeds the threshold and the measurement value of its received signal power S,i or the measurement value of the SINR.

[0060] Furthermore, for example, if the reception conditions are not good, the terminal station 4 notifies the base station 2 or the control device 1 via the base station 2 of a beam change request. The change request includes, for example, a beam ID that exceeds a threshold, and requests that the currently used beam be stopped and changed to a beam that exceeds the threshold. The change request may also include, for example, a beam ID(i) that exceeds the threshold, and a measurement value of its received signal power St,i or a measurement value of its SINR.

[0061] The beam change request may include phases P1 to P3 in the beam management procedure exemplified in Fig. 2. For example, depending on whether the orientation of the terminal station 4 has changed, the terminal station 4 may select one of the following: (1) restarting beam management from phase P1, (2) restarting beam management from phase P2, or (3) executing only phase P3 (see Figs. 11 and 13).

[0062] Fig. 10 is a diagram illustrating a single threshold Th0 for received signal power St,i or SINR. The configuration of the graph in Fig. 10 is the same as the upper or lower diagram in Fig. 9. However, in Fig. 10, threshold Th0 is set for received signal power St,i on the vertical axis. As a result, in Fig. 10, it is determined that the received signal power (black graph) used in data communication and the received signal power before and after it exceed the threshold value Th0. Note that, similar to Fig. 10, the terminal station 4 can also determine the SINR by grasping the relationship between the measured value for each beam and the threshold value Th0.

[0063] 11 is a flowchart illustrating a threshold determination process A for the received signal power St,i or SINR. This process illustrates details of the determinations S6 and S9 in FIG. 7 and S21 in FIG.

[0064] In this process, the terminal station 4 first determines whether or not the measurement value of the beam in use exceeds the threshold value Th0 (S210). If the measurement value of the beam in use is within the threshold value Th0, the terminal station 4 proceeds to the process at S218. That is, in this case, the terminal station 4 determines that the beam change process is "necessary." However, as will be explained in S219 and S21A, the beam change process differs depending on whether or not the orientation of the terminal station 4 has changed.

[0065] If the measurement value of the beam in use exceeds the threshold value Th0, the terminal station 4 then determines the number of beam patterns Nok that exceed the threshold value Th0. A beam pattern refers to the pattern of the beam gain (directivity), and the number of patterns Nok essentially means the number of beam types. Hereinafter, the number of beam patterns Nok will be simply referred to as the number of beam patterns.

[0066] Then, the terminal station 4 determines whether the number Nok of beam patterns exceeding the threshold value Th0 is equal to or less than the first reference value Nth,rep (S211). If the number Nok of beam patterns whose measurement values ​​exceed the threshold value Th0 exceeds the first reference value Nth,rep, the terminal station 4 returns to the next process, for example, S6 or S9 in Fig. 7 or S21 in Fig. 8, without reporting the reception status or requesting a change of beam.

[0067] On the other hand, if the number Nok of beam patterns whose measured values ​​exceed the threshold Th0 is within the first reference value Nth,rep, the terminal station 4 determines whether the number Nok of beam patterns whose measured values ​​exceed the threshold Th0 is equal to or less than a second reference value Nth,new (S212), where the second reference value Nth,new is a value even smaller than the first reference value Nth,rep.

[0068] If the number Nok of beam patterns exceeding the threshold value Th0 exceeds the second reference value Nth,new, the terminal station 4 sets the reception status report to "required" (S213). Then, the terminal station 4 returns to the next process, for example, S6 or S9 in FIG. 7 or S21 in FIG. 8.

[0069] If it is determined in S212 that the number Nok of beam patterns exceeding the threshold value Th0 is within the second reference value Nth,new, the terminal station 4 further determines whether the orientation of the terminal station 4 has changed between the previous (t-1th) measurement and the current (tth) measurement (S218). The processing of S218 can also be called angle detection processing. The method for determining whether the orientation of the terminal station 4 has changed has already been described in S21 of FIG. 8.

[0070] If it is determined in S218 that the orientation of the terminal station 4 has not changed, the terminal station 4 sets the beam change from phase P1 (see FIG. 2) in the beam management processing to "necessary" (S219), and returns to the processing next to, for example, S6 or S9 in FIG. 7, or S21 in FIG. 8. In this case, the terminal station 4 requests the base station 2 or the control device 1 via the base station 2 to restart phase P1, i.e., beam management, from the beginning. This is because if the orientation of the terminal station 4 has not changed, there is a high possibility that there is no problem with the reception beam of the terminal station 4, and that the orientation of the transmission beam of the base station 2 has shifted.

[0071] On the other hand, if it is determined in step S218 that the orientation of the terminal station 4 has changed, the terminal station 4 The terminal station 4 sets the beam change from phase P3 in the system management processing to "required" (S21A), and returns to the processing next to, for example, S6 or S9 in FIG. 7, or S21 in FIG. 8. In this case, the terminal station 4 will change the reception beam of the terminal station 4 in phase P3, that is, in the beam management. In this case, there is no problem with the transmission beam of the base station 2, and it is highly likely that the reception beam of the terminal station 4 is simply misaligned. Note that even if the determination in S210 is NO, the processing from S218 onwards is executed.

[0072] FIG. 12 illustrates multiple thresholds ThA and ThB for received signal power St,i or SINR. The graph in FIG. 10 has the same configuration as FIG. 10. However, in FIG. 12, thresholds ThA (solid line) and ThB (dotted line) are set for received signal power St,i on the vertical axis. Furthermore, threshold ThB is set to a value lower than threshold ThA. As a result, in FIG. 12, the received signal power used in data communication (black graph) and the received signal powers before and after it are determined to exceed the lower threshold ThB. However, only the received signal power used in data communication (black graph) is determined to exceed the higher threshold ThA. Note that such determination based on multiple thresholds ThA, ThB, etc. may be performed for SINR in addition to received signal power St,i.

[0073] Fig. 13 is a flowchart illustrating a decision process B using two thresholds ThA and ThB for received signal power St,i or SINR. This process illustrates, for example, details of decisions S6 and S9 in Fig. 7 and S21 in Fig. 8, and can be said to be a modification of the process in Fig. 11. Here, as in Fig. 12, it is assumed that threshold ThA is greater than threshold ThB.

[0074] In this process, the terminal station 4 first determines whether or not the measurement value of the beam in use exceeds the threshold value ThB (S220). If the beam in use is within the threshold value ThB, the terminal station 4 proceeds to S228. That is, in this case, similar to the determination in S210 of FIG. 11, the terminal station 4 determines that the beam change process is "necessary."

[0075] If the beam in use exceeds the threshold value ThB, the terminal station 4 next determines whether there is a beam pattern whose measurement value exceeds a threshold value ThA that is greater than the threshold value ThB (S221). If there is a beam pattern that exceeds the threshold value ThA, the terminal station 4 determines that a report of the reception status and a request to change the beam are both "unnecessary" (S223). That is, in this case, the terminal station 4 does not report the reception status or request a change of the beam, and returns to the next process, for example, S6 or S9 in FIG. 7 or S21 in FIG. 8.

[0076] If it is determined in S221 that there is no beam whose measurement value exceeds the threshold value ThA, the terminal station 4 determines the number of beam patterns Nok whose measurement value exceeds the threshold value ThB. Then, it determines whether the number of beam patterns Nok whose measurement value exceeds the threshold value ThB is equal to or less than the first reference value Nth,rep (S224). If the number of beam patterns Nok whose measurement value exceeds the threshold value ThB exceeds the first reference value Nth,rep, the terminal station 4 determines that a report of the reception status and a request to change the beam are "unnecessary" (S225). That is, in this case, the terminal station 4 does not report the reception status or request a change of the beam, and returns to the next process, for example, S6 or S9 in FIG. 7 or S21 in FIG. 8.

[0077] On the other hand, if it is determined in S224 that the number Nok of beam patterns whose measurement values ​​exceed the threshold ThB is equal to or less than the first reference value Nth,rep, the terminal station 4 determines whether the number Nok of beam patterns whose measurement values ​​exceed the threshold ThB is equal to or less than a second reference value Nth,new (S226), where the second reference value Nth,new is a value even smaller than the first reference value Nth,rep.

[0078] If the number Nok of beam patterns exceeding the threshold value ThB exceeds the second reference value Nth,new, the terminal station 4 sets the reception status report to "required" (S227). For example, the process returns to the process next to S6 or S9 in FIG. 7 or S21 in FIG.

[0079] On the other hand, if it is determined in S226 that the number Nok of beam patterns exceeding the threshold ThB is within the second reference value Nth,new, the terminal station 4 further determines whether the orientation of the terminal station 4 has changed (S228). The processes of S228, S229, and S22A are the same as the processes of S218, S219, and S21A in FIG.

[0080] 14 is a diagram illustrating a threshold determination process for the difference between the previous measurement result (received signal power St-1,i) and the current measurement result (received signal power St,i). This process can be said to be a modified example of the process of S21 in FIG. 8, shown in FIGS. 11 and 13.

[0081] In this process, the terminal station 4 first calculates the difference between the previous measurement result (received signal power St-1,i) and the current measurement result (received signal power St,i) (G1). In the graph shown in G1, the horizontal axis represents the beam ID and the vertical axis represents the difference value St,i-St-1,i. Here, t is a subscript indicating the measurement result in the t-th reception, but also indicates the timing of the measurement. Therefore, t-1 corresponds to a first point in time, and t corresponds to a second point in time that is later than the first point in time.

[0082] Then, the terminal station 4 binarizes the difference value St,i-St-1,i (arrow A3, graph G2). For example, if the difference value St,i-St-1,i is a positive value and is equal to or greater than the reference judgment value, the difference value St,i-St-1,i is set to 1. If the difference value St,i-St-1,i is a negative value and its absolute value is equal to or greater than the reference judgment value, the difference value St,i-St-1,i is set to -1. On the other hand, if the absolute value of the difference value St,i-St-1,i is less than the judgment value, it is set to 0. By binarizing, it is possible to prevent a large number of small difference values ​​from accumulating and affecting the judgment.

[0083] Then, the terminal station 4 adds the binarized difference values ​​St,i-St-1,i for each beam ID to obtain a sum (arrow A4). The determination based on this sum is as follows. For example, the terminal station 4 determines whether or not a reception status report is required (arrow A5). That is, if the obtained sum is equal to or greater than zero, the terminal station 4 does not report the reception status or request a beam change. Also, if the obtained sum is negative, the terminal station 4 reports the reception status.

[0084] Furthermore, for example, the terminal station 4 determines whether or not a beam change is necessary (arrow A6). That is, regardless of whether the calculated sum is positive or negative, if the difference value of the beam used in data communication is negative, the terminal station 4 requests a beam change. On the other hand, if the difference value of the beam used in data communication is 0 or greater, the terminal station 4 does not request a beam change. However, the process in FIG. 14 above is just an example, and the process of the terminal station 4 is not limited to that in FIG. 14. For example, the binarization process may be omitted.

[0085] Fig. 15 is a diagram illustrating the details of the reporting process after the necessity determination (details of S10 in Fig. 7 and S22 in Fig. 8) and the beam change request process (details of S22 in Fig. 8). However, Fig. 15 also describes that the necessity determination determined that a report is necessary, that is, that a report of the reception status is "required."

[0086] If the determination result indicates that a report is required, the terminal station 4 determines whether the number Nok of beam patterns exceeding the threshold value Th0 in Fig. 11 or the smaller threshold value ThB in Fig. 13 is equal to or less than a third reference value (S230). Here, the third reference value is used to determine how to report the reception status, and is a value determined experimentally or empirically.

[0087] If it is determined in step S230 that the number of beam patterns Nok is equal to or less than the third reference value, the terminal station 4 , and performs a high-frequency report (S231). High-frequency reporting is a reporting method in which the reception status is repeatedly notified to the base station 2 or to the control device 1 via the base station 2. As described in S302 of FIG. 6, the control device 301 of the comparative example notifies the terminal station 304 of information on the set beam and the slot for the terminal station 304 to report the reception status. This also applies to S2 of FIG. 7 in the processing of the control device 1 of this embodiment.

[0088] Typically, multiple slots are designated for the terminal station 304 of the comparative example and the terminal station 4 of this embodiment to report reception status. These slots are accessed through contention among multiple terminal stations 4, and data transmission is carried out. Therefore, in high-frequency reporting, the terminal station 4 uses more of the designated slots than usual, to the extent possible, to report reception status.

[0089] For example, the terminal station 4 may report the reception status using all designated slots. FIG. 15 illustrates an example in which, when the number Nok of beam patterns exceeding the threshold value Th0 or ThB is 1, the reception status is repeatedly reported in all designated slots. However, frequent reporting is not limited to repeatedly reporting the reception status in all slots. The terminal station 4 may perform frequent reporting according to a specified value, such as P1 (a number less than 100) percent of the designated slots.

[0090] The process of S231 can be said to be an example of notifying a report using communication resources equal to or greater than a predetermined number of resources among the communication resources allocated by the control device 1 for notifying a report. Also, in the process of S231, the slots for reporting the reception status are an example of communication resources allocated by the control device 1. Also, making reports in all slots or making high-frequency reports according to a specified value such as P1 percent of the specified slots are examples of notifying a report using communication resources equal to or greater than a predetermined number of resources.

[0091] On the other hand, if the determination in S230 shows that the number of beam patterns Nok exceeds the third reference value, the terminal station 4 makes a low-frequency report (S232). A low-frequency report is a reporting method that notifies the base station 2 or the control device 1 via the base station 2 of the reception status using fewer slots than a high-frequency report.

[0092] For example, the terminal station 4 may report the reception status using only one designated slot. FIG. 15 illustrates an example in which the reception status is reported only once in one slot when the number of beam patterns Nok exceeding the threshold value Th0 or ThB is 2 or more. However, the infrequent reporting is not limited to reporting the reception status only once in a single slot. The terminal station 4 may perform infrequent reporting according to a specified value, for example, P2 percent (a number smaller than P1) of the designated slot.

[0093] The process of S232 is an example of transmitting a report using communication resources within a predetermined number of resources among the communication resources allocated by the control device 1 for transmitting the report. Also, reporting the reception status only once or reporting infrequently according to a specified value such as P2 (a number smaller than P1) percent of a specified slot are examples of transmitting a report using communication resources within a predetermined number of resources.

[0094] Fig. 15 illustrates examples of high-frequency reports and low-frequency reports in reception status reports. However, the frequency of notifications when the terminal station 4 requests a beam change can also be controlled in the same manner as in Fig. 15. That is, the terminal station 4 can notify the control device 1 via the base station 2 of a beam change request at a high or low frequency depending on the number of beam patterns Nok that exceed the threshold value Th0 or ThB.

[0095] FIG. 16 is a diagram illustrating another example of the details of the reporting process after the necessity determination (details of S10 in FIG. 7 and S22 in FIG. 8) and the beam change request process (details of S22 in FIG. 8). In FIG. 16, if the necessity determination determines that a report is necessary, the terminal station 4 determines whether the number Nok of beam patterns exceeding the threshold Th0 in FIG. 11 or the smaller threshold ThB in FIG. 13 is equal to or less than a fourth reference value (S240). Here, the fourth reference value is used to determine how to report the reception situation and is a value determined experimentally or empirically. The fourth reference value may also be the same as the third reference value in FIG. 15.

[0096] 16, if it is determined in S240 that the number of beam patterns Nok is equal to or less than the fourth reference value, the terminal station 4 reports in a priority slot (S241). A priority slot is a slot that is likely to arrive at the base station 2 first or at the control device 1 via the base station 2.

[0097] 15, multiple slots are normally designated for the terminal station 4 to report the reception status, and they are arranged in the time axis direction. Therefore, when reporting in a priority slot, the terminal station 4 reports the reception status using the slot with the earliest possible transmission timing among the designated slots.

[0098] 16 illustrates, for example, when the number of beam patterns Nok is 1, the reception status is reported using the first two slots on the time axis among the designated slots. However, the processing of S241 is not limited to reporting the reception status using the first two slots. The processing of S241 is an example of reporting the report using communication resources that are preferentially transmitted among communication resources allocated by the control device 1 for reporting the report.

[0099] On the other hand, if the determination in S240 indicates that the number of beam patterns Nok exceeds the fourth reference value, the terminal station 4 reports in a normal slot (S242). A report in a normal slot is a report that does not specify a particular reporting slot. For the normal slot, the terminal station 4 appropriately transmits a communication request to the control device 1, and the control device 1 determines the reporting slot for the terminal station 4, and the normal slot is then notified to the terminal station 4. Alternatively, the terminal station 4 may select and use a pre-assigned notification slot other than the priority slot in order of earliest transmission timing. Also, for example, the terminal station 4 may randomly select an available slot other than the priority slot from the pre-assigned notification slots. For example, FIG. 16 illustrates that when the number of beam patterns Nok is 1, the terminal station 4 reports in a normal slot.

[0100] 16 illustrates examples of reception status reports using priority slots and normal slots. However, when terminal station 4 requests a beam change, the priority of the notification can also be controlled in the same way as in FIG. 16. That is, terminal station 4 can notify base station 2 or the control device 1 via base station 2 of a beam change request in the priority slot or normal slot depending on the number of beam patterns Nok whose measurement value exceeds threshold value Th0 or ThB.

[0101] 17 is a diagram illustrating another method of the reporting process after determining whether a change is necessary (details of S10 in FIG. 7 and S22 in FIG. 8) and the beam change request process (details of S22 in FIG. 8). In FIGS. 15 and 16, the reception status report is notified immediately after determining the number of beam patterns Nok. However, the terminal station 4 may notify the reception status report in two stages.

[0102] In the process of Fig. 17, the determination in S250 is the same as S240 in Fig. 16. In the example of Fig. 17, if the determination in S250 is that the number of beam patterns Nok is equal to or less than the fourth reference value, the terminal station 4 notifies the base station 2 or the control device 1 via the base station 2 in the priority slot as a first step that a reception status report has become "necessary" (S251). If the number of patterns Nok exceeds the fourth reference value, the terminal station 4 notifies the base station 2 or the control device 1 via the base station 2 in a normal slot as a first step that a reception status report is "necessary" (S252). In the processes of S251 and S252, the notification is made in as few slots as possible. For example, this notification is made with a data amount that is short enough to fit in a single slot. The process of S252 is an example of notifying the control device 1 of a request to allocate communication resources to be used for reporting the reception status.

[0103] Then, the base station 2 or the control device 1 allocates a slot for reporting to the terminal station 4 (S252). The number of slots allocated for reporting here is greater than the number of slots used for the notification in S251 and S252.

[0104] When the slot for reporting is assigned, the terminal station 4 reports the reception status using the assigned slot as the second step (S253). Note that when requesting a beam change, the processing is the same as in FIG.

[0105] In this way, by having the terminal station 4 report the reception status or request a beam change in a two-stage process, communication resources can be potentially saved. That is, in the first stage, the terminal station 4 simply reports that a reception status report is "needed" or that a beam change is "needed" using as little data as possible that fits in as few slots as possible. Then, in the second stage, the reception status report itself or the beam change request itself can be notified in the allocated slot. In this way, by using two-stage processing, the communication systems 100A and 100B can reduce the number of reporting slots that the terminal station 4 initially occupies. That is, there is no need to initially allocate a large number of reporting slots to the terminal station 4 before it is determined that a reception status report or a beam change is actually required.

[0106] 17, the priority slot and the normal slot are used depending on the number of beam patterns Nok. However, the two-stage processing by the terminal station 4 is not limited to that shown in FIG. 17. That is, if the necessity determination determines that a report is necessary, the terminal station 4 may omit S250 and perform either notification in the priority slot in S251 or notification in the normal slot in S252.

[0107] (Effects of the embodiment) As described above, in this embodiment, the terminal station 4 receives radio signals from multiple beams transmitted under the control of the control device 1 on the network N1, and measures the received signals. Then, the terminal station 4 determines whether to notify the control device 1 of a report of the measured received signals based on the measurement results of the measured received signals. Then, if it is decided to notify the report, the terminal station 4 notifies the control device 1 of the report. In this way, the terminal station 4 does not notify the control system including the control device 1 and the base station 2 of a report of the reception status unless it is decided to notify the report. Therefore, the terminal station 4 can suppress communication traffic due to reports of the reception status, reduce the consumption of communication resources, and reduce overhead.

[0108] Here, the control device 1 cooperates with the base station 2 on the network N1 to provide a wireless access network. That is, the control device 1 and the base station 2 function as one control system. This also applies to the following description.

[0109] The terminal station 4 determines whether or not to change the beam used for communication with the control device 1 (or base station 2) based on the measurement result of the received signal. If it is determined that the beam used for communication should be changed, the terminal station 4 notifies the control device 1 of a request to change the beam used for communication. In this way, the terminal station 4 can notify the beam change request. Unless a beam change request is determined, the beam change request is not notified to the control system including the control device 1 and the base station 2. Therefore, the terminal station 4 can suppress communication traffic due to the notification of the beam change request, reduce the consumption of communication resources, and reduce overhead.

[0110] When the number of beams whose measurement values ​​exceed thresholds Th0 and ThB is equal to or less than a first reference value in the measurement results when wireless signals from multiple beams are received, the terminal station 4 decides to report the reception status to the control device 1. Therefore, when there are few good beams, the terminal station 4 reports the reception status to the control device 1. As a result, the terminal station 4 consumes communication resources by limiting reports to those that are necessary. In other words, the terminal station 4 can avoid unnecessary reports when reporting the reception status and reduce overhead.

[0111] When the number of beams whose measurement values ​​exceed the thresholds Th0 and ThB is equal to or less than a second reference value that is smaller than the first reference value, the terminal station 4 determines to change the beam to be used for communication. Therefore, the terminal station 4 consumes communication resources only when a beam change is necessary. In other words, the terminal station 4 can avoid unnecessary notification of radio signals when requesting a beam change, thereby reducing overhead.

[0112] The terminal station 4 decides to change the beam to be used for communication when the measurement value of the beam currently being used for communication with the control device 1 does not reach the thresholds Th0, ThB, etc. In other words, if the beam state is not desirable for the current communication, the terminal station 4 can immediately request the control device 1 to change the beam.

[0113] When the terminal station 4 receives radio signals from multiple beams and finds that there is a beam whose measurement value exceeds a first threshold value ThA in the measurement results, the terminal station 4 does not report to the control device 1. In this case, the terminal station 4 does not change the beam used for communication. On the other hand, when there is no beam whose measurement value exceeds the first threshold value ThA and the number of beams whose measurement value exceeds a second threshold value ThB that is smaller than the first threshold value ThA is equal to or less than the first reference value, the terminal station 4 reports the reception status to the control device 1. In this way, the terminal station 4 reports the reception status only when necessary. Therefore, the terminal station 4 can reduce the consumption of communication resources due to reporting the reception status. In other words, the terminal station 4 can avoid unnecessary reports when reporting the reception status and reduce overhead.

[0114] The terminal station 4 calculates a difference between the measurement result when radio signals are received by multiple beams at a first time point (t-1) and the measurement result when radio signals are received by multiple beams at a second time point (t) after the first time point (t-1). If the sum of the difference values ​​for the multiple beams is negative, the terminal station 4 then decides to notify the control device 1 of a report of the reception status. In other words, the terminal station 4 can determine whether or not a report of the reception status is necessary depending on the change over time of the multiple beams.

[0115] Furthermore, the terminal station 4 decides to change the beam to be used for communication when the difference value becomes negative for the beam currently being used for communication with the control device 1. Therefore, the terminal station 4 can change the beam to be used for communication while suppressing consumption of communication resources in accordance with the change over time of the beam currently being used for communication.

[0116] When it is decided to change the beam used for communication, the terminal station 4 determines whether or not the orientation of the terminal station 4 in three-dimensional space has changed before, during, or after the process of measuring the received signal. If the orientation has changed, the terminal station 4 decides to change the receiving beam at the terminal station 4. In other words, the terminal station 4 determines that the deterioration of the received signal is caused by the terminal station 4 itself, and can adjust the receiving beam appropriately. .

[0117] When it is decided to notify a reception status report, if the number of beams whose measurement values ​​exceed the threshold value Th0 (or ThB) is equal to or less than a third reference value, the terminal station 4 notifies the report by repeating the report a number of times greater than normal. More specifically, the terminal station 4 notifies the report by using a predetermined number or more of communication resources (slots) allocated by the control device 1 for notifying the reception status report. Therefore, the terminal station 4 can notify the reception status report with increased reliability by using many communication resources, if necessary.

[0118] When it is decided to notify a reception status report, if the number of beams whose measurement values ​​exceed the threshold value Th0 (or ThB) exceeds a third reference value, the terminal station 4 notifies the report with a smaller number of repetitions than when the number of beams is within the third reference value. More specifically, the terminal station 4 notifies the report using communication resources (slots) within a predetermined number of resources among the communication resources (slots) allocated by the control device 1 for notifying the reception status report. Therefore, if a certain number of beam patterns are available, the terminal station 4 can notify the reception status report while suppressing consumption of communication resources.

[0119] When it is decided to notify a reception status report, if the number of beams whose measurement values ​​exceed the threshold value Th0 (ThB) is equal to or less than a fourth reference value, the terminal station 4 notifies the report as early as possible. More specifically, the terminal station 4 notifies the report using a communication resource that is preferentially transmitted among the communication resources (slots) allocated by the control device 1 for notifying the reception status report. Therefore, the terminal station 4 can notify the reception status report at an early timing using a communication resource with a high priority, if necessary.

[0120] When it is decided that the terminal station 4 should notify a reception status report, the terminal station 4 notifies the control device 1 of a request to allocate communication resources to be used for the report, using data smaller than the data size used for reporting the reception status. Then, after the communication resources are allocated by the control device 1, the terminal station 4 notifies the report using the data size used for the report. Therefore, the terminal station 4 can prevent unnecessary consumption of communication resources before it is decided that the terminal station 4 should notify a reception status report. This also applies when it is decided that the terminal station 4 should notify a beam change request. Therefore, the terminal station 4 can prevent unnecessary consumption of communication resources before it is decided that the terminal station 4 should notify a beam change request.

[0121] <Other embodiments> The above-described embodiment is merely an example, and the present disclosure may be modified as appropriate within the scope of the present disclosure. Furthermore, the processes and means described in the present disclosure may be freely combined and implemented as long as no technical contradiction occurs.

[0122] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by one device. The hardware configuration (server configuration) by which each function is realized in each of the terminal station 4, the control device 1, and the base station 2, or in the communication systems 100A and 100B, can be flexibly changed.

[0123] The present disclosure can also be realized by supplying a computer program that implements the functions described in the above embodiments to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer by a non-transitory computer-readable storage medium connectable to the system bus of the computer, or may be provided to the computer via a network. A non-transitory computer-readable storage medium includes any type of medium suitable for storing electronic instructions, such as, for example, any type of disk, such as a magnetic disk (e.g., a floppy disk, a hard disk drive (HDD), etc.), an optical disk (e.g., a CD-ROM, a DVD disk, a Blu-ray disk), a read-only memory (ROM), a random-access memory (RAM), an EPROM, an EEPROM, a magnetic card, a flash memory, or an optical card. [Explanation of symbols]

[0124] 1. Control device 2 base station 2A central base station 2B distributed base station 4 Terminal Station 11 CPU 12 Main storage 13 External storage device 16. Communications equipment 21, 21B, 41 Radio 22, 22A, 42 control circuit 50 vehicles

Claims

1. receiving radio signals from a plurality of beams transmitted under control of a network control device and measuring the received signals; determining whether to notify the control device of a report of the measured received signal based on a measurement result of the received signal; and notifying the control device of the report if it is determined to notify the report.

2. The controller determines whether to change the beam used for communication with the control device based on the measurement result; The terminal station according to claim 1 , wherein when it is determined to change the beam to be used for the communication, the terminal station notifies the control device of a request to change the beam to be used for the communication.

3. The terminal station according to claim 2, wherein the controller decides to notify the control device of the report when the number of beams whose measurement values ​​exceed a threshold in the measurement results when receiving the radio signals from the multiple beams is less than or equal to a first reference value.

4. The terminal station according to claim 3, wherein the controller decides to change the beam to be used for the communication when the number of beams whose measurement values ​​exceed the threshold is equal to or less than a second reference value that is smaller than the first reference value.

5. The terminal station according to claim 3 , wherein the controller determines to change the beam to be used for the communication when the measurement value of the beam currently used for the communication with the control device does not reach the threshold.

6. the controller, when there is a beam whose measurement value exceeds a first threshold in the measurement results when receiving the wireless signals from the plurality of beams, determines not to notify the control device of the report and not to change the beam used for the communication; The terminal station of claim 2, further comprising: determining to notify the control device of the report when there are no beams whose measurement values ​​exceed the first threshold and when the number of beams whose measurement values ​​exceed a second threshold smaller than the first threshold is less than or equal to a first reference value.

7. The terminal station of claim 6, wherein the controller decides to change the beam to be used for the communication when the number of beams whose measurement values ​​exceed the second threshold is equal to or less than a second reference value that is smaller than the first reference value.

8. The terminal station according to claim 2, wherein the controller calculates a difference value between the measurement result when the radio signal is received by the plurality of beams at a first point in time and the measurement result when the radio signal is received by the plurality of beams at a second point in time after the first point in time, and decides to notify the control device of the report when the sum of the difference values ​​for the plurality of beams is negative.

9. The terminal station according to claim 8 , wherein the controller determines to change the beam to be used for the communication when the difference value becomes negative for the beam currently being used for the communication with the control device.

10. When it is determined to change the beam used for the communication, the controller determines whether or not to change the beam before or after the process of measuring the received signal, or during the process of measuring the received signal.

3. The terminal station according to claim 2, wherein the terminal station determines whether or not there has been a change in orientation of the terminal station in three-dimensional space, and if there has been a change in orientation, determines to change the reception beam of the terminal station.

11. The terminal station of claim 1, wherein when it is decided to notify the report, if the number of beams whose measurement values ​​exceed a threshold is less than or equal to a third reference value, the controller notifies the report using a predetermined number or more of communication resources allocated by the control device to notify the report.

12. The terminal station of claim 11, wherein when it is decided to notify the report, if the number of beams whose measurement values ​​exceed the threshold exceeds the third reference value, the controller notifies the report using communication resources within the specified number of resources among the communication resources allocated by the control device for notifying the report.

13. The terminal station of claim 1, wherein when it is decided to notify the report, if the number of beams whose measurement values ​​exceed the threshold is less than or equal to a fourth reference value, the controller notifies the report using a communication resource that is preferentially transmitted among the communication resources allocated by the control device for notifying the report.

14. the controller notifies the control device of a request for allocation of communication resources to be used for the report, using data smaller than a data size used for the report when it is determined to notify the report; 2. The terminal station according to claim 1, further comprising: after the communication resource is allocated by the control device, notifying the report with the data size used for the report.

15. The terminal station of claim 14, wherein the controller notifies the allocation request using a communication resource that is preferentially transmitted among the communication resources allocated by the control device to notify the allocation request when the number of beams whose measurement values ​​exceed the threshold is equal to or less than a fourth reference value.

16. receiving radio signals from a plurality of beams transmitted under control of a network control device and measuring the received signals; determining whether to notify the control device of a report of the measured received signal based on a measurement result of the received signal; a terminal station including a controller that executes the following: when it is determined to notify the report, notifying the control device of the report; and a communication system comprising the control device.

17. The terminal station receiving radio signals from a plurality of beams transmitted under control of a network control device and measuring the received signals; determining whether to notify the control device of a report of the measured received signal based on a measurement result of the received signal; If it is determined that the report should be notified, notifying the control device of the report.

18. the terminal station determines whether to change the beam used for communication with the control device based on the measurement result; 18. The communication method according to claim 17, wherein when it is determined to change the beam to be used for the communication, a request to change the beam to be used for the communication is notified to the control device. 。

19. The communication method described in claim 18, wherein the terminal station decides to notify the control device of the report when the number of beams whose measurement values ​​exceed a threshold in the measurement results when receiving the radio signals from the multiple beams is less than or equal to a first reference value.

20. The communication method of claim 19, wherein the terminal station decides to change the beam to be used for the communication when the number of beams whose measurement values ​​exceed the threshold is equal to or less than a second reference value that is smaller than the first reference value.

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