Information processing device, information processing method, and information processing system

Abstract

Provided are an information processing device, an information processing method, and an information processing system that are capable of preventing data loss in one-to-many communications. The information processing device comprises: an MBS communication processing unit that transmits data by one-to-many communications using a plurality of beams transmitted at different timings while sweeping in the surroundings; and a beam notification processing unit that transmits timing information about the timing at which the data is transmitted using the plurality of beams.

Description

Information processing device, information processing method, and information processing system

[0001] This application claims priority to Japanese Patent Application No. 2023-166583, filed on September 28, 2023, the contents of which are incorporated herein by reference.

[0002] Currently, communication using a Multicast Broadcast Service (MBS) is being standardized. For example, Non-Patent Document 1 defines a PTM (Point to Multipoint) mode as multicast communication for transmitting data to multiple users, and a PTP (Point to Point) mode as unicast transmission for transmitting data to an individual user.

[0003] 3GPP TS 38.300 v17.1.0, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2 (Release 17)”

[0004] Non-Patent Document 1 describes handover between base stations compatible with MBS communication, specifically, that sequence numbers are synchronized at the packet level. Data transmission by MBS using beamforming has also been studied. However, specific methods for transmitting data by MBS to an area within a cell using beamforming and beam switching methods have not been fully studied.

[0005] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide an information processing device, an information processing method, and an information processing system that are capable of preventing data loss in one-to-many communication.

[0006] An information processing device of one embodiment of the present disclosure includes an MBS communication processing unit that transmits data using one-to-many communication using multiple beams that sweep around the area and are each transmitted at different times, and a beam notification processing unit that transmits timing information regarding the timing at which the data will be transmitted by the multiple beams.

[0007] An information processing method according to one embodiment of the present disclosure is an information processing method executed by an information processing device, which transmits data using point-to-multipoint communication using a plurality of transmission beams that sweep around and are transmitted at different times, and transmits timing information regarding the timing at which the data is transmitted by the plurality of beams.

[0008] An information processing system of one embodiment of the present disclosure comprises an information processing device and a terminal device, wherein the information processing device transmits data using one-to-many communication using multiple transmission beams that sweep around the information processing device and are each transmitted at different timings, and transmits timing information regarding the timing at which the data is transmitted by the multiple beams, and the terminal device receives the data transmitted by MBS based on the timing indicated by the timing information.

[0009] According to the present disclosure, it is possible to provide an information processing device, an information processing method, and an information processing system that are capable of preventing data loss in one-to-many communication.

[0010] FIG. 1 is a conceptual diagram of an information processing system according to a first embodiment. FIG. 2 is a diagram showing transmission timing of an MBS signal by beam transmission. FIG. 3 is a functional block diagram showing an example of a schematic configuration of a base station shown in FIG. 1. FIG. 4 is a functional block diagram showing an example of a schematic configuration of a terminal device shown in FIG. 1. FIG. 5 is a sequence diagram showing a first example of processing executed in the information processing system shown in FIG. 1. FIG. 6 is a sequence diagram showing a second example of processing executed in the information processing system shown in FIG. 1. FIG. 7 is a flowchart showing an example of processing executed by the terminal device shown in FIG. 1. FIG. 8 is a functional block diagram showing an example of a schematic configuration of a base station according to a second embodiment. FIG. 9 is a sequence diagram showing an example of processing executed in the information processing system according to the second embodiment. FIG. 10 is a flowchart showing an example of processing executed by a base station in the second embodiment. FIG. 11 is a flowchart showing an example of processing executed by a terminal device in the second embodiment.

[0011] Hereinafter, several embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or equivalent components are denoted by the same reference numerals, and redundant descriptions of identical or equivalent components will be omitted as appropriate.

[0012] [First Embodiment] Fig. 1 is a conceptual diagram of an information processing system 1 according to a first embodiment. As shown in Fig. 1, the information processing system 1 includes a base station 10 and a terminal device 20. Although the conceptual diagram shown in Fig. 1 illustrates one base station 10 and multiple terminal devices 20, the number of base stations 10 and terminal devices 20 included in the information processing system 1 is not necessarily limited to the number illustrated in Fig. 1, and the information processing system 1 may include one or more base stations 10 and one or more terminal devices 20.

[0013] The base station 10 provides a communication network using a predetermined wireless communication method. The predetermined wireless communication method is, for example, a communication method using a fifth-generation mobile communication system (5G system). Specifically, the base station 10 is a base station that applies the NR (New Radio) standard, which is a radio access technology (RAT) for 5G cellular mobile communication systems. The base station 10 is connected to a 5G core network 30 so that information can be communicated.

[0014] The terminal device 20 is a terminal device capable of communicating information with the base station 10. The terminal device 20 performs data communication with the base station 10 using a communication network provided by the base station 10. The terminal device 20 may be, for example, a router terminal, a smartphone, or a tablet terminal.

[0015] In this embodiment, the base station 10 transmits data using a point-to-multipoint communication technique. In the following description, the point-to-multipoint communication technique is assumed to be an MBS communication technique. That is, the base station 10 transmits data using signals according to the MBS method. In this specification, signals transmitted via MBS are also referred to as "MBS signals," and data transmitted via MBS signals are also referred to as "MBS data." The base station 10 transmits MBS signals as beams. Specifically, as shown by the dashed arrows in FIG. 1 , the base station 10 sweeps n beams, from beam 1 to beam n (n is an integer greater than or equal to 1), and transmits MBS signals around the base station 10 at different timings. Note that the present disclosure is equally applicable to point-to-multipoint communication techniques other than MBS communication. Point-to-multipoint communication is a communication method for transmitting data to multiple devices (terminal devices 20 in this embodiment) in a single transmission.

[0016] Figure 2 shows the transmission timing of MBS signals by beam transmission. In Figure 2, the horizontal axis represents the passage of time. The square frames in each beam represent time slots, and "A," "B," and "C" represent the data to be transmitted.

[0017] As shown in FIG. 2 , the base station 10 transmits data A using beam 1 in the first time slot. The base station 10 transmits data A using beam 2 in the second time slot following the first time slot. By repeating this process, the base station 10 transmits data A using beam n in the nth time slot. Next, the base station 10 transmits data B, which is to be transmitted after data A, using beam 1 in the (n+1)th time slot. The base station 10 also transmits data B using an adjacent beam in each time slot using the same procedure as for transmitting data A. After transmitting data B using beam n in the 2nth time slot, the base station 10 then transmits the next data C using beam 1 in the 2n+1th time slot. The base station 10 also transmits data C using the same procedure as for data A and data B. In this way, the base station 10 transmits data sequentially while shifting the timing for each slot.

[0018] A terminal device 20 present within a range where it can receive beam 1 of the base station 10 can receive data A in the first time slot, data B in the (n+1)th time slot, and data C in the (2n+1)th time slot. Similarly, a terminal device 20 present within a range where it can receive beam 2 of the base station 10 can receive data A in the second time slot, data B in the (n+2)th time slot, and data C in the (2n+2)th time slot. Terminal devices 20 present within a range where it can receive other beams can also receive MBS data at the timing when data is transmitted in each beam.

[0019] Fig. 3 is a functional block diagram showing an example of a schematic configuration of the base station 10 shown in Fig. 1. As shown in Fig. 3, the base station 10 includes, as functional units, a control unit 11, a storage unit 12, and a wireless communication unit 13.

[0020] The control unit 11 controls and manages the entire base station 10, including each functional unit of the base station 10. The control unit 11 includes at least one processor. The control unit 11 is configured with a processor such as a CPU (Central Processing Unit) that executes a program that defines a control procedure, or a dedicated processor specialized for processing each function. The control unit 11 includes an MBS communication processing unit 111 and a unicast communication processing unit 112 as functional units that execute communication processing.

[0021] The MBS communication processing unit 111 performs processing related to MBS communication. Specifically, the MBS communication processing unit 111 performs processing related to NR multicast communication for all terminal devices 20 within the communication cell of the base station 10. The processing related to multicast communication includes, for example, allocation of shared radio resources to the terminal devices 20. The MBS communication processing unit 111 generates, for example, MBS data. For example, as described with reference to FIG. 2 , the MBS communication processing unit 111 transmits the MBS data to the terminal devices 20 by beam-transmitting an MBS signal including the MBS data via the radio communication unit 13.

[0022] In this embodiment, the MBS communication processing unit 111 includes an MBS beam notification processing unit 111a as a functional unit. The MBS beam notification processing unit 111a generates timing information regarding the timing at which MBS data is transmitted by multiple beams, and transmits the timing information to the terminal device 20 within the cell of the base station 10. Details of the timing information will be described later.

[0023] The MBS communication processing unit 111 generates MBS information as processing related to MBS communication and transmits it to the terminal device 20. The MBS information is information related to MBS communication, and includes, for example, program information. The program information is information related to programs (content) provided by MBS communication. The MBS information may also include timing information. In this case, the MBS communication processing unit 111 includes the timing information generated by the MBS beam notification processing unit 111a in the MBS information and transmits it to the terminal device 20. The MBS information is transmitted to the terminal device 20 that is capable of receiving MBS data by MBS communication.

[0024] The unicast communication processing unit 112 generates broadcast information as processing related to unicast communication or MBS communication and transmits it to the terminal device 20. The broadcast information is information necessary for the terminal device 20 to perform multicast communication with the base station 10, and includes, for example, frequency information. The MBS information may also include timing information. In this case, the MBS communication processing unit 111 includes the timing information generated by the MBS beam notification processing unit 111a in the broadcast information and transmits it to the terminal device 20. The broadcast information can be received by all terminal devices 20 within the cell of the base station 10. Note that the MBS communication processing unit 111 may also generate the broadcast information.

[0025] The unicast communication processing unit 112 performs processing related to unicast communication. Specifically, the unicast communication processing unit 112 performs processing related to NR unicast communication for a terminal device 20 that performs unicast communication with the base station 10. The processing related to unicast communication includes, for example, allocating individual radio resources to the terminal device 20. The unicast communication processing unit 112 generates, for example, data to be transmitted to the terminal device 20 that performs unicast communication (hereinafter also referred to as "unicast data"). The unicast communication processing unit 112 transmits, for example, the generated unicast data to the terminal device 20 that performs unicast communication. Note that in this embodiment, if the base station 10 does not perform unicast communication with the terminal device 20, it may not necessarily include the unicast communication processing unit 112. Note that unicast communication is an example of one-to-one communication. Therefore, in the present disclosure, unicast communication does not necessarily have to be used, and other one-to-one communication may be used instead of unicast communication. One-to-one communication is a communication method in which data is transmitted to one device (terminal device 20 in this embodiment) in one transmission.

[0026] The storage unit 12 is a storage medium capable of storing programs and data. The storage unit 12 can be configured, for example, with a semiconductor memory or a magnetic memory. The storage unit 12 stores, for example, a program for operating the base station 10. The storage unit 12 stores, for example, timing information. The storage unit 12 also stores, for example, data transmitted by MBS communication or unicast communication. The storage unit 12 may also store information on the beams currently being used for communication by each of the multiple terminal devices 20.

[0027] The wireless communication unit 13 transmits and receives data (wireless signals) by wireless communication via an antenna. The wireless signals are used for data communication with the terminal device 20. By transmitting and receiving data, data communication between the base station 10 and the terminal device 20 is performed. The control unit 11 performs predetermined processing on the data received by the wireless communication unit 13. The predetermined processing is well-known processing including, for example, AD conversion and Fourier transform. Furthermore, the wireless communication unit 13 transmits, from the antenna, the MBS data generated by the MBS communication processing unit 111 or the unicast data generated by the unicast communication processing unit 112.

[0028] Fig. 4 is a functional block diagram showing an example of a schematic configuration of the terminal device 20 shown in Fig. 1. As shown in Fig. 4, the terminal device 20 includes, as functional units, a control unit 21, a storage unit 22, a wireless communication unit 23, a display unit 24, and an input unit 25.

[0029] The control unit 21 controls and manages the entire terminal device 20, including each functional unit of the terminal device 20. The control unit 21 includes at least one processor. The control unit 21 is configured with a processor such as a CPU that executes a program that defines a control procedure, or a dedicated processor specialized for processing each function.

[0030] The control unit 21 receives, for example, data transmitted from the base station 10 and performs appropriate processing on the received data. For example, the control unit 21 causes the display unit 24 to display a display screen based on the received data.

[0031] The storage unit 22 is a storage medium capable of storing programs and data. The storage unit 22 may be configured, for example, as a semiconductor memory or a magnetic memory. The storage unit 22 stores, for example, programs for operating the terminal device 20.

[0032] The wireless communication unit 23 transmits and receives data by wireless communication via an antenna. By transmitting and receiving data, data communication is performed between the base station 10 and the terminal device 20. The control unit 21 performs predetermined processing on the data received by the wireless communication unit 23. The predetermined processing is well-known processing including, for example, AD conversion and Fourier transform. The wireless communication unit 23 also transmits a wireless signal generated by the control unit 21 from the antenna. For example, the wireless communication unit 23 transmits an MBS data request, which is a signal requesting the transmission of MBS data, to the base station 10.

[0033] The display unit 24 includes a display device such as a liquid crystal display (LCD), an organic electroluminescence panel (OLED), or an inorganic electroluminescence panel. The display unit 24 displays characters, images, symbols, figures, and the like. The display unit 24 may be configured as a touchscreen display that not only has a display function but also a touchscreen function. In this case, the touchscreen detects contact with the user's finger, a stylus pen, or the like of the terminal device 20.

[0034] The input unit 25 accepts operation input from the user of the terminal device 20. The input unit 25 is configured by, for example, operation buttons (operation keys). The input unit 25 may be configured by a touch screen, and an input area for accepting operation input from the user may be displayed on a part of the display device that is the display unit 24, thereby accepting touch operation input from the user.

[0035] Next, an example of processing executed in the information processing system 1 will be described. Fig. 5 is a sequence diagram showing a first example of processing executed in the information processing system 1 shown in Fig. 1. The first example is a processing example when timing information is included in the MBS information. At the start of the sequence in Fig. 5, it is assumed that the terminal device 20 is located in a position where it can receive beam 1 transmitted by the base station 10, and can receive MBS data via beam 1.

[0036] The base station 10 transmits MBS information periodically, for example (step S1). If an MBS data reception request has not occurred in step S3 (to be described later), the terminal device 20 does not receive the MBS information.

[0037] Furthermore, the base station 10 periodically transmits MBS data to the terminal device 20 (step S2). If an MBS data reception request has not occurred in step S3 (described later), the terminal device 20 does not receive the MBS information transmitted in step S1 or the MBS data transmitted in step S2.

[0038] Next, assume that an MBS data reception request for requesting reception of MBS data occurs in the terminal device 20 (step S3). The MBS data reception request is generated by the control unit 21, for example, when a need arises within the terminal device 20 to receive predetermined data from the base station 10. As an example, the MBS data reception request is generated based on a request from a predetermined application or the like running on the terminal device 20.

[0039] As in step S1, the base station 10 periodically transmits MBS information to the terminal device 20 (step S4). At this time, since the MBS data reception request has occurred in step S3, the terminal device 20 receives the MBS information transmitted by beam 1. In the processing of the first example, the MBS information includes timing information. That is, the base station 10 includes the timing information generated by the MBS beam notification processing unit 111a in the MBS information and transmits the MBS information to the terminal device 20.

[0040] Here, the timing information in the first example will be described. Here, it is assumed that the difference in timing when multiple beams are transmitted is equal. In other words, the difference in timing when beam 1 and beam 2 are transmitted is equal to the difference in timing when beam 2 and beam 3 are transmitted. The same applies to the other beams. Here, the difference in timing when adjacent beams are transmitted is assumed to be α.

[0041] In the first example, the timing information included in the MBS information transmitted by beam i (i is an integer between 1 and n) includes information on the timing of transmission of beam i and the difference α between the timings of transmission of adjacent beams among multiple beams. The terminal device 20 can recognize the timing of transmission of beam i by acquiring the timing information included in the MBS information. In step S4 of the flow in Figure 5, the terminal device 20 recognizes the transmission timing of beam 1.

[0042] It should be noted that, when the terminal device 20 receives the MBS information in step S4, it does not need to receive any more MBS information thereafter. This is because the terminal device 20 has already acquired timing information by receiving the MBS information once, and therefore does not need to acquire the same timing information again.

[0043] Furthermore, the base station 10 periodically transmits MBS data to the terminal device 20, as in step S2 (step S5). The terminal device 20 receives the MBS data transmitted by beam 1 at the transmission timing of beam 1 acquired in step S4. In other words, by recognizing the transmission timing, the terminal device 20 can receive the MBS data in the time slot in which beam 1 is transmitted. As a result, the terminal device 20 receives the specified data in response to the MBS data reception request generated in step S3.

[0044] Next, it is assumed that the terminal device 20 decides to switch the beam received from the base station 10. Here, it is assumed that the terminal device 20 decides to switch the beam received from the base station 10 from beam 1 to beam 2 (step S6). The terminal device 20 measures, for example, downlink reference signals (CSI-RS) of multiple beams transmitted from the base station 10, and decides to switch the currently used beam (beam 1 in this case) to the beam with the highest wireless quality (beam 2 in this case). It should be noted that known methods can be used for determining whether to switch beams and for determining the beam to switch to. Here, it is assumed that the terminal device 20 decides to switch from beam 1 to beam 2.

[0045] Based on the determination in step S6, the terminal device 20 switches the beam received from the base station 10 to beam 2 (step S7). At this time, the terminal device 20 switches the timing of receiving MBS data from the timing of beam 1 to the timing of beam 2. For example, the terminal device 20 calculates the transmission timing of beam 2 based on the timing information included in the MBS information received in step S4. Specifically, the terminal device 20 can calculate the transmission timing of beam 2 by adding the difference α to the transmission timing of beam 1. Note that, since the terminal device 20 has acquired the information on the difference α, it can calculate the timing of any beam transmitted from the base station 10. That is, the terminal device 20 can calculate the transmission timing of any beam i by adding the difference α × (i-1) to the transmission timing of beam 1.

[0046] The base station 10 continues transmitting the MBS data to the terminal device 20 by beam transmission (step S8). After switching to beam 2 in step S7, the terminal device 20 receives the MBS data transmitted by beam 2 at the transmission timing of beam 2 after switching. In other words, the terminal device 20 can receive the MBS data in the time slot in which beam 2 is transmitted. In this way, the terminal device 20 can receive the data transmitted as an MBS based on the timing indicated by the timing information.

[0047] As described with reference to Figure 5, the processing of the first example allows the terminal device 20 to switch the beam for receiving MBS data. That is, by the base station 10 transmitting timing information to the terminal device 20, even when the terminal device 20 switches the beam used for receiving data, the terminal device 20 can receive the MBS data with the switched beam based on the timing indicated by the timing information. Therefore, it is possible to prevent the terminal device 20 from being unable to receive MBS data due to beam switching, and as a result, it is possible to prevent data loss. Note that the processing of the first example is applicable even when unicast communication is not available (i.e., uplink communication from the terminal device 20 to the base station 10 is not available).

[0048] Fig. 6 is a sequence diagram showing a second example of processing executed in the information processing system 1 shown in Fig. 1. The second example is a processing example when timing information is included in the broadcast information. At the start of the sequence in Fig. 6, the terminal device 20 is located in a position where it can receive beam 1 transmitted by the base station 10, and is able to receive MBS data via beam 1.

[0049] The base station 10 transmits broadcast information to the terminal device 20 (step S11). The base station 10 periodically transmits the broadcast information by beam transmission while sweeping the beam. At this time, the terminal device 20 receives the broadcast information transmitted by beam 1. In the processing of the second example, the broadcast information includes timing information. That is, the timing information generated by the MBS beam notification processing unit 111a is included in the broadcast information and transmitted to the terminal device 20.

[0050] Here, the timing information in the second example will be explained. Here, it is assumed that the difference in timing when multiple beams are transmitted is equal. In the second example, the timing information included in the MBS information transmitted by beam i (i is an integer between 1 and n) includes the difference α in timing when adjacent beams are transmitted. In the second example, the timing information does not need to include the timing of transmission of beam i. This makes it possible to reduce the amount of timing information included in the broadcast information that can be received by all terminal devices 20 in the cell.

[0051] Next, assume that an MBS data reception request for requesting reception of MBS data occurs in the terminal device 20 (step S12). In this case, the terminal device 20 transmits an MBS data request, which is a signal requesting MBS data, to the base station 10 (step S13). At this time, the terminal device 20 transmits the MBS data request using unicast communication.

[0052] The base station 10 transmits MBS information to the terminal device 20 based on the MBS data request received from the terminal device 20 (step S14). For example, information required for the terminal device 20 to acquire the MBS information can be notified to the terminal device 20 by transmitting information such as the transmission timing of the periodically transmitted MBS information using a downlink unicast signal. The MBS information transmitted at this time includes information regarding the timing of transmission of beam i. In this case, since the terminal device 20 can receive MBS data using beam 1, the MBS information includes information regarding the transmission timing of beam 1. The terminal device 20 receives the MBS information transmitted using beam 1.

[0053] The base station 10 also transmits the MBS data to the terminal device 20 (step S15). The terminal device 20 receives the MBS data transmitted by beam 1 at the transmission timing of beam 1 acquired in step S14. That is, the terminal device 20 receives the MBS data in the time slot in which beam 1 is transmitted.

[0054] Next, it is assumed that the terminal device 20 decides to switch the beam received from the base station 10. Here, it is assumed that the terminal device 20 decides to switch the beam received from the base station 10 from beam 1 to beam 2 (step S16).

[0055] Based on the decision made in step S16, the terminal device 20 switches the beam received from the base station 10 to beam 2 (step S17). For example, the terminal device 20 switches the timing of receiving MBS data from the timing of beam 1 to the timing of beam 2. At this time, the terminal device 20 calculates the transmission timing of beam 2 based on the transmission timing of beam 1 included in the MBS information received in step S14 and the difference α included in the timing information included in the broadcast information received in step S11. The specific calculation method is the same as the method described in the first example, and therefore a detailed description will be omitted here.

[0056] The base station 10 continues transmitting the MBS data to the terminal device 20 by beam transmission (step S18). After switching to beam 2 in step S17, the terminal device 20 receives the MBS data transmitted by beam 2 at the transmission timing of beam 2 after switching. In other words, the terminal device 20 can receive the MBS data in the time slot in which beam 2 is transmitted.

[0057] In this way, even in the second example, the terminal device 20 can switch the beam for receiving MBS data. Therefore, for the same reason as in the first example, even in the second example, it is possible to prevent the terminal device 20 from being unable to receive MBS data, and it is possible to prevent data loss.

[0058] In the second example, it was explained that the timing information includes the difference α between the timings at which adjacent beams are transmitted, but does not include the timing of the transmission of beam i. However, even in the second example, the timing information may include the difference α between the timings at which adjacent beams are transmitted and the timing of the transmission of beam i. In this case, information regarding the transmission timing of beam i does not need to be included in the MBS information.

[0059] Furthermore, in the first and second examples described above, it has been explained that the terminal device 20 receives both the difference α between the timings at which adjacent beams are transmitted and the timing of the transmission of beam i, and calculates the transmission timing of an arbitrary beam based on this information. However, instead of this, the terminal device 20 may receive information regarding the transmission timing of all beams. In this case, the terminal device 20 does not need to calculate the transmission timing of the beams. In the first and second examples described above, the difference α between the timings at which adjacent beams are transmitted is a constant value. However, if the difference α between the timings at which adjacent beams are transmitted is not a constant value, the terminal device 20 can recognize information regarding the transmission timing of an arbitrary beam by receiving information regarding the transmission timing of all beams.

[0060] Fig. 7 is a flowchart showing an example of processing executed by the terminal device 20 shown in Fig. 1 in this embodiment. With reference to Fig. 7, an example of processing executed by the terminal device 20 will be described.

[0061] The control unit 21 of the terminal device 20 performs a beam search (step S21). That is, the control unit 21 detects a signal beam-transmitted from the base station 10.

[0062] The control unit 21 receives timing information transmitted from the base station 10 (step S22). Specifically, the control unit 21 acquires timing information contained in the signal transmitted by the beam based on the signal from the base station 10 detected in step S21. The timing information is contained in the MBS information or the broadcast information, for example, as described in the first or second example above. Note that if multiple beams are detected by the beam search in step S21, the control unit 21 receives the signal transmitted by the beam with the highest wireless quality.

[0063] The control unit 21 calculates the reception timing of the MBS data based on the timing information received in step S22 (step S23). That is, the control unit 21 calculates the reception timing of the MBS data transmitted by the beam to be used based on the difference α between the transmission timing of the beam i and the transmission timing of the adjacent beam.

[0064] Then, the control unit 21 receives the MBS data transmitted by the beam to be used at the reception timing calculated in step S23 (step S24).

[0065] The control unit 21 also checks the wireless quality of the beam in use and the wireless quality of its surrounding beams (step S25). For example, the control unit 21 checks the wireless quality of the surrounding beams whose quality has been notified in advance by the base station and whose quality should be checked.

[0066] Then, the control unit 21 determines whether the wireless quality of the current beam is better than that of the other beams (step S26). That is, the control unit 21 compares the wireless quality of the currently used beam with the wireless quality of the other receivable beams. If the wireless quality of the currently used beam is higher than that of the other receivable beams, the control unit 21 determines that the wireless quality of the current beam is better than that of the other beams. Note that the control unit 21 may execute steps S25 and S26 as appropriate. Therefore, steps S25 and S26 do not necessarily have to be performed in the order of the flow shown in FIG. 7.

[0067] If the control unit 21 determines that the wireless quality of the current beam is better than the other beams (Yes in step S26), it continues to use the current beam and proceeds to step S24.

[0068] On the other hand, if the control unit 21 determines that the wireless quality of the current beam is not better than that of the other beams (No in step S26), the control unit 21 decides to switch the beam to be used (step S27). For example, the control unit 21 decides to switch to the beam with the highest wireless quality among the available beams.

[0069] Then, the control unit 21 calculates the reception timing of the MBS data transmitted by the determined beam to be switched to (step S28). The method of calculating the reception timing of the MBS data is the same as, for example, step S23, and therefore description thereof will be omitted. Thereafter, the control unit 21 proceeds to step S24, and receives the MBS data transmitted by the switched beam at the reception timing of the switched beam.

[0070] Second Embodiment Next, a second embodiment will be described. The schematic configuration of the information processing system 1 according to the second embodiment is the same as that of the first embodiment, for example, the same as that described with reference to Fig. 1. The information processing system 1 according to the second embodiment will be described focusing on the differences from the first embodiment, while omitting the description of the same points as those in the first embodiment as appropriate.

[0071] 8 is a functional block diagram showing an example of a schematic configuration of a base station 10 according to the second embodiment. In the base station 10 according to the second embodiment, the unicast communication processing unit 112 includes an MBS data transmission processing unit 112a as a functional unit. Except for the fact that the unicast communication processing unit 112 includes the MBS data transmission processing unit 112a, the configuration of the base station 10 according to the second embodiment is the same as that of the first embodiment.

[0072] The MBS data transmission processing unit 112a performs a transmission process of MBS data by unicast communication. Specifically, when the beam used by the terminal device 20 is switched, the MBS data transmission processing unit 112a performs a transmission process to the terminal device 20 of MBS data that the terminal device 20 cannot receive by beam transmission of multicast communication. A specific example of the MBS data transmission processing unit 112a performing the MBS data transmission process will be described later.

[0073] Fig. 9 is a sequence diagram showing an example of processing executed in the information processing system 1 according to the second embodiment. The sequence shown in Fig. 9 is an example in which the terminal device 20 switches the beam it uses from beam n to beam 1. Therefore, at the start of the sequence in Fig. 9, the terminal device 20 is located in a position where it can receive beam n transmitted by the base station 10, and is able to receive MBS data via beam n. In the example shown in Fig. 9, timing information is included in the broadcast information.

[0074] The base station 10 transmits broadcast information to the terminal device 20 (step S31). The base station 10 periodically transmits the broadcast information by beam transmission while sweeping the beam. The terminal device 20 receives the broadcast information transmitted by beam n.

[0075] Next, assume that an MBS data reception request for requesting reception of MBS data occurs in the terminal device 20 (step S32). In this case, the terminal device 20 transmits the MBS data request to the base station 10 (step S33). At this time, the terminal device 20 transmits the MBS data request using unicast communication.

[0076] The base station 10 transmits MBS information to the terminal device 20 based on the MBS data request received from the terminal device 20 (step S34). For example, information required for the terminal device 20 to acquire the MBS information can be notified to the terminal device 20 by transmitting information such as the transmission timing of the periodically transmitted MBS information using a downlink unicast signal. The MBS information transmitted at this time includes information regarding the timing of transmission of beam i. In this case, since the terminal device 20 is capable of receiving MBS data using beam n, the MBS information includes information regarding the transmission timing of beam n. The terminal device 20 receives the MBS information transmitted using beam n.

[0077] The base station 10 also transmits the MBS data to the terminal device 20 (step S35). The terminal device 20 receives the MBS data transmitted by beam n at the transmission timing of beam n acquired in step S34. That is, the terminal device 20 receives the MBS data in the time slot in which beam n is transmitted.

[0078] Next, it is assumed that the terminal device 20 decides to switch the beam received from the base station 10. Here, it is assumed that the terminal device 20 decides to switch the beam received from the base station 10 from beam n to beam 1 (step S36).

[0079] When the terminal device 20 determines to switch beams in step S36, it transmits information about the beam to be used (hereinafter also referred to as "used beam information") to the base station 10 (step S37). The used beam information includes at least information that can identify the beam to be switched to. In this case, since the beam to be switched to is beam 1, the used beam information includes information that can identify beam 1, such as the ID of beam 1.

[0080] In step S37, the terminal device 20 may transmit to the base station 10, instead of the used beam information, beam-identifying information and the measurement values ​​of the downlink reference signals for all beams for which the terminal device 20 has measured the downlink reference signals. In this case, the base station 10 determines the beam to switch to based on the measurement values ​​received from the terminal device 20. In this case, the base station 10 notifies the terminal device 20 of the determined beam information to switch to.

[0081] Furthermore, based on the decision made in step S36, the terminal device 20 switches the beam received from the base station 10 to beam 1 (step S38). For example, the terminal device 20 switches the timing of receiving MBS data from the timing of beam n to the timing of beam 1. At this time, the terminal device 20 calculates the transmission timing of beam 1 based on the transmission timing of beam n included in the MBS information received in step S34 and the difference α included in the timing information included in the broadcast information received in step S31.

[0082] The base station 10 determines whether or not to transmit MBS data based on the used beam information received from the terminal device 20 (step S39). For example, the base station 10 stores information on the beam being used for each terminal device 20 in the storage unit 12. When the base station 10 receives the used beam information, it rewrites the information on the beam being used by the terminal device 20 stored in the storage unit 12 to the information on the beam indicated by the received used beam information. In this example, since the terminal device 20 has switched the beam being used from beam n to beam 1, the base station 10 switches the information on the beam being used by the terminal device 20 stored in the storage unit 12 from beam n to beam 1.

[0083] At this time, the base station 10 determines whether or not it is necessary to transmit MBS data to the terminal device 20, which is the target of rewriting the information of the beam in use. As described with reference to FIG. 2, for example, the MBS data is transmitted as beams, shifting the time slots in order from beam 1 to beam n. Therefore, if the terminal device 20 switches the beam it uses from beam x to beam y, with x<y, the terminal device 20 can receive the MBS data on the beam y after the switch. For example, in the example shown in FIG. 2, the timing at which data A is transmitted is later for beam n than for beam 1. Therefore, if the beam it uses is switched from beam 1 to beam n, the terminal device 20 can receive data A on the beam n after the switch.

[0084] On the other hand, when beam y is switched to beam x, the terminal device 20 may not be able to receive MBS data using beam x after the switch. For example, when the terminal device 20 switches the beam it uses from beam n to beam 1, the timing at which data A is transmitted is later for beam n than for beam 1. Therefore, for example, if data A is transmitted using beam 1 and then the terminal device 20 switches the beam it uses from beam n to beam 1 before transmitting data A using beam n, the terminal device 20 cannot receive data A using beam n before the switch, and cannot receive data A using beam 1 after the switch because data A has already been transmitted. In other words, data A cannot be received in time using beam 1 after the switch. In this way, beam switching may prevent data reception. Therefore, when the base station 10 determines, based on the beam usage information received from the terminal device 20, that the terminal device 20 is able to receive MBS data using the beam after the switch, it determines that transmission of MBS data is unnecessary. On the other hand, when the base station 10 determines, based on the beam usage information received from the terminal device 20, that the terminal device 20 has not been able to receive MBS data using the beam after switching, the base station 10 determines that transmission of MBS data is necessary. For example, when the beam in use is switched from beam x to beam y, the base station 10 determines that transmission of MBS data is unnecessary, and when the beam in use is switched from beam y to beam x, the base station 10 determines that transmission of MBS data is necessary. The base station 10 may further determine whether or not transmission of MBS data is necessary based on the timing at which the beam is switched by the terminal device 20. Note that in this embodiment, MBS data that the terminal device 20 has not been able to receive using the beam before switching due to beam switching is also referred to as "unreceived data" hereinafter.

[0085] Here, it is assumed that the base station 10 determines that it is necessary to transmit MBS data. In this case, the MBS data transmission processing unit 112a of the base station 10 transmits the unreceived data to the terminal device 20 by unicast communication of beam 1 (step S40). Here, the unreceived data is data that would have been transmitted by multicast communication if the beam had not been switched. In other words, if the beam has been switched, in step S40, the MBS data that is normally transmitted by multicast communication is transmitted to the terminal device by unicast communication. In this way, by transmitting MBS data that is assumed to be inaccessible to the terminal device 20 by unicast communication, the terminal device 20 can receive the data without any loss, even if the beam has been switched.

[0086] The base station 10 also continues transmitting MBS data to the terminal device 20 by beam transmission (step S41). After switching from beam n to beam 1 in step S38, the terminal device 20 receives the MBS data transmitted by beam 1 at the transmission timing of beam 1 after switching. In other words, the terminal device 20 can receive the MBS data in the time slot in which beam 1 is transmitted.

[0087] Fig. 10 is a flowchart showing an example of processing executed by the base station 10 in the second embodiment. The base station 10 executes the flow shown in Fig. 10 together with beam transmission in multicast communication, for example.

[0088] For example, the base station 10 collects used beam information of each terminal device 20 in the cell (step S51). That is, the base station 10 collects the used beam information described in step S37 of Fig. 9 from each terminal device 20. The base station 10 may collect measurement values ​​of downlink reference signals measured by the terminal devices 20 instead of the used beam information.

[0089] In step S51, the control unit 11 of the base station 10 determines whether or not the used beam information has been received from the terminal device 20 (step S52). If the control unit 11 determines that the used beam information has not been received (No in step S52), the control unit 11 proceeds to step S51 and repeats steps S51 and S52 until it determines that the used beam information has been received.

[0090] On the other hand, when the control unit 11 determines that it has received the beam-in-use information (Yes in step S52), it determines whether or not it is necessary to switch the beam for the terminal device 20 (step S53). For example, when the beam indicated by the beam-in-use information received from the terminal device 20 is different from the beam used by the terminal device 20 stored in the storage unit 12, the control unit 11 determines that it is necessary to switch the beam for the terminal device 20. Alternatively, when the control unit 11 receives the measurement value of the downlink reference signal measured by the terminal device 20 in step S51, it determines in step S53 whether the radio quality of a beam other than the beam currently used by the terminal device 20 is higher than the radio quality of the beam currently used by the terminal device 20. In this case, when it determines that the radio quality of the beam other than the beam currently used by the terminal device 20 is higher than the radio quality of the beam currently used by the terminal device 20, it determines that it is necessary to switch the beam for the terminal device 20.

[0091] If the control unit 11 determines that beam switching is not necessary (No in step S53), the control unit 11 proceeds to step S51 without changing the beam used by the terminal device 20.

[0092] On the other hand, if the control unit 11 determines that beam switching is necessary (Yes in step S53), it switches the beam used by the terminal device 20 (step S54). For example, the control unit 11 switches the beam by rewriting the information on the beam used by the terminal device 20, which is stored in the storage unit 12, with information on another beam indicated by the used beam information. Alternatively, the control unit 11 switches the beam by rewriting the information on the beam used by the terminal device 20, which is stored in the storage unit 12, with information on another beam with higher wireless quality.

[0093] Then, the control unit 11 determines whether the terminal device 20 will be able to receive the data via the switched beam in time (step S55). The processing of step S55 is an example of the processing of step S39 in Fig. 9. That is, the control unit 11 determines whether the terminal device 20 can receive the MBS data that the terminal device 20 was unable to receive via the beam before switching by switching the beam via the beam after switching. If the terminal device 20 can receive the MBS data, it is determined that the terminal device 20 will be able to receive the data via the switched beam in time (Yes in step S55).

[0094] In step S55, for example, if the transmission timing of the MBS data of the beam to be switched is delayed compared to the transmission timing of the beam before the switch, the control unit 11 can determine that the terminal device 20 will be able to receive the data via the beam after the switch. For example, assuming x<y as in the above example, if the beam to be switched is beam y and the beam before the switch is beam x, the transmission timing of the MBS data of the beam y after the switch is delayed compared to the transmission timing of the MBS data of the beam before the switch. In this case, the control unit 11 determines that the terminal device 20 will be able to receive the data via the beam after the switch. Conversely, if the transmission timing of the MBS data of the beam to be switched is earlier than the transmission timing of the MBS data of the beam before the switch, the control unit 11 can determine that the terminal device 20 will not be able to receive the data via the beam after the switch. For example, if the beam to be switched is beam x and the beam before the switch is beam y, the transmission timing of the MBS data of the beam x after the switch is earlier than the transmission timing of the MBS data of the beam before the switch. In this case, the control unit 11 determines that the terminal device 20 will not be able to receive data in time via the switched beam.

[0095] Alternatively, in step S55, the control unit 11 may determine whether the terminal device 20 will be able to receive data via the switched beam based on the timing of beam switching (e.g., the time slot in which the switching occurs) and the timing of reception of MBS data via the beam transmitted by the terminal device 20 after the switching (the time slot in which the MBS data is received). For example, if the time difference between the timing of beam switching by the terminal device 20 and the timing of reception of MBS data via the beam transmitted by the terminal device 20 after the switching is equal to or greater than a threshold range, the control unit 11 determines that the terminal device 20 will be able to receive data via the switched beam in time; if the time difference is less than the threshold range, the control unit 11 determines that the terminal device 20 will not be able to receive data via the switched beam in time. In this case, the base station 10 acquires information on the beam switching allowable time for each terminal device 20 within the threshold range in advance. The base station 10 can acquire this information by, for example, receiving information on the beam switching allowable time from each terminal device 20.

[0096] If the control unit 11 determines that the terminal device 20 will be able to receive data in time via the switched beam (Yes in step S55), the control unit 11 proceeds to step S51.

[0097] On the other hand, if the control unit 11 determines that the terminal device 20 will not be able to receive the data via the switched beam in time (No in step S55), the MBS data transmission processing unit 112a transmits the MBS data determined to be too late to the terminal device 20 via unicast communication (step S56). The processing of step S56 corresponds to the processing of step S40 in Fig. 9. This allows the base station 10 to transmit all data to the terminal device 20 without any loss, even if the terminal device 20 switches the beam.

[0098] Fig. 11 is a flowchart showing an example of processing executed by the terminal device 20 in the second embodiment. In Fig. 11, the processing from step S21 to step S28 is the same as step S21 to step S28 described with reference to Fig. 7 in the first embodiment, and therefore detailed description thereof will be omitted here.

[0099] If it is determined in step S27 that beam switching is to be performed, the terminal device 20 receives a data reception instruction from the base station 10 (step S29). The data reception instruction is a signal instructing the terminal device 20 by the base station 10 to receive MBS data transmitted by unicast communication. For example, if the base station 10 determines in step S39 of Fig. 9 that MBS data transmission is necessary, the base station 10 transmits a data reception instruction to the terminal device 20 before transmitting the MBS data in step S40. By receiving the data reception instruction, the terminal device 20 can recognize that MBS data will be transmitted from the base station 10 by unicast communication.

[0100] After receiving the data reception instruction, the terminal device 20 receives the MBS data from the base station 10 via unicast communication (step S30). In this way, the terminal device 20 can receive, via unicast communication, the MBS data that may be lost due to beam switching.

[0101] Although the present disclosure has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various modifications and alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included in the scope of the present disclosure. For example, functions included in each functional unit or step can be rearranged so as not to be logically inconsistent, and multiple functional units or steps can be combined or divided into one.

Claims

1. An information processing device comprising: a communication processing unit that transmits data using one-to-many communication by multiple beams that are transmitted at different times while sweeping around; and a beam notification processing unit that transmits timing information regarding the timing at which the data is transmitted by the multiple beams.

2. An information processing device according to claim 1, wherein the timing information includes information on the difference in timing between transmissions of adjacent beams among the plurality of beams.

3. An information processing device further comprising a data transmission processing unit that, when a terminal device receiving the data switches the beam used to receive the data, transmits the unreceived data that the terminal device was unable to receive using the beam before the switching to the terminal device via one-to-one communication if it determines that the terminal device cannot receive the unreceived data using the beam after the switching.

4. The information processing device according to claim 1, wherein the one-to-many communication is a multicast broadcast service (MBS).

5. An information processing method executed by an information processing device, comprising: transmitting data using point-to-multipoint communication using multiple transmission beams that are transmitted at different timings while sweeping around; and transmitting timing information regarding the timing at which the data is transmitted by the multiple beams.

6. An information processing system comprising an information processing device and a terminal device, wherein the information processing device transmits data using point-to-multipoint communication by a plurality of transmission beams that are transmitted at different timings while sweeping around the information processing device, and transmits timing information regarding the timing at which the data is transmitted by the plurality of beams, and the terminal device receives the data transmitted using the point-to-multipoint communication based on the timing indicated by the timing information.

7. The information processing system of claim 6, wherein the terminal device, when switching the beam used to receive the data, calculates the reception timing of the data transmitted by the switched beam based on the timing information, and receives the data transmitted by the switched beam at the calculated reception timing.

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