Communication system, roadside device, program, and communication method

Abstract

A communication system (100) comprises: a vehicle (110); a roadside device (130) disposed along a road on which the vehicle (110) travels; and a server-side system (150) that predicts the communication quality of a communication path from a V2X application server (152), which provides V2X service to the vehicle (110), to the roadside device (130). The roadside device (130) sequentially transmits a prediction request, prediction information, and position information indicating the position of the roadside device (130) to the server-side system (150) at predetermined time intervals. Each time the server-side system (150) receives the prediction request, the server-side system (150) predicts the communication quality using the prediction information and the position information indicating the position of the roadside device (130), and sequentially transmits the prediction results to the roadside device (130). The roadside device (130) sequentially stores the prediction results, and transmits the stored latest prediction result to the vehicle (110) upon receiving a prediction request from the vehicle (110).

Description

Communication system, roadside device, program, and communication method

[0001] The present disclosure relates to a communication system, a roadside device, a program, and a communication method.

[0002] Known V2X (Vehicle to X) services include remote driving, autonomous driving, and autonomous parking. To realize V2X services, QoS (Quality of Service) is predicted. The predicted QoS Sustainability is notified to the vehicle, allowing the vehicle to take action such as stopping the vehicle, slowing down, or steering before the QoS deteriorates. This notification is also called IQN (In-advance QoS Notification). This action is also called V2X adaptation.

[0003] QoS Sustainability is predicted by a request from a vehicle to a server, which predicts the QoS at the vehicle's location and transmits it to the vehicle (see, for example, Non-Patent Document 1).

[0004] 3GPP TS 23.287 V18.1.0, 2023

[0005] However, in order for a vehicle to receive QoS Sustainability, it is necessary to go through the sequence described in Non-Patent Document 1 and the like. Therefore, there is a problem in that the delay time until the vehicle receives QoS Sustainability becomes larger than the allowable delay time for receiving QoS Sustainability in the V2X application, resulting in a delay in V2X adaptation.

[0006] Therefore, one or more aspects of the present disclosure aim to reduce the delay until a vehicle receives QoS Sustainability.

[0007] A communication system according to one aspect of the present disclosure includes a vehicle, a roadside device arranged along a road on which the vehicle travels, and a prediction system that predicts communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, wherein the roadside device sequentially transmits a prediction request requesting a prediction of the communication quality, prediction information that is information necessary for the prediction, and location information that indicates a location of the roadside device to the prediction system at a predetermined time interval, the prediction system predicts the communication quality using the prediction information and the location information each time it receives a prediction request, and sequentially transmits prediction results that are the results of the prediction to the roadside device, and the roadside device sequentially stores the prediction results, and when it receives a prediction request from the vehicle, transmits the latest stored prediction result to the vehicle.

[0008] A roadside device according to one aspect of the present disclosure is a roadside device that is arranged along a road on which a vehicle travels, and is characterized in that it includes: a first communication unit that sequentially transmits, to a prediction system that predicts communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, prediction requests that request a prediction of the communication quality, prediction information that is information necessary for the prediction, and location information that indicates a location of the roadside device, to the prediction system at predetermined time intervals; and sequentially receives prediction results that are results of the prediction from the prediction system in response to the prediction requests; a storage unit that stores the prediction results; a second communication unit that receives the prediction requests from the vehicle; and a read control unit that, when the prediction request from the vehicle is received, reads out the latest stored prediction result and causes the second communication unit to transmit the read prediction result to the vehicle.

[0009] A program according to one aspect of the present disclosure is a program that causes a computer to function as a roadside device arranged along a road on which a vehicle travels, and causes the computer to function as: a first communication unit that sequentially transmits, at predetermined time intervals to a prediction system that predicts communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, prediction requests that request a prediction of communication quality, prediction information that is information necessary for the prediction, and location information that indicates a location of the roadside device, and sequentially receives prediction results that are results of the prediction from the prediction system in response to the prediction requests; a memory unit that stores the prediction results; a second communication unit that receives the prediction requests from the vehicle; and a read control unit that, when the prediction request from the vehicle is received, reads out the latest stored prediction result and causes the second communication unit to transmit the read prediction result to the vehicle.

[0010] A communication method according to one aspect of the present disclosure is a communication method performed by a roadside device arranged along a road on which a vehicle travels, the method comprising: transmitting, to a prediction system that predicts communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, a prediction request requesting a prediction of the communication quality, prediction information that is information necessary for the prediction, and location information that indicates a location of the roadside device, at predetermined time intervals; sequentially receiving prediction results that are results of the prediction from the prediction system in response to the prediction request; storing the prediction results; receiving a prediction request from the vehicle; and, when the prediction request from the vehicle is received, reading out the latest stored prediction result and transmitting the read out prediction result to the vehicle.

[0011] According to one or more aspects of the present disclosure, it is possible to reduce the delay until a vehicle receives QoS Sustainability.

[0012] 1 is a block diagram schematically showing the configuration of a communication system according to a first embodiment. FIG. 2 is a sequence diagram of a first IQN as a comparative example. FIG. 3 is a sequence diagram of a second IQN as a comparative example. FIG. 4 is a block diagram schematically showing the configuration of a main part of a vehicle according to the first embodiment. FIGS. 1A and 1B are block diagrams showing an example hardware configuration. FIG. 5 is a block diagram showing the schematic configuration of a roadside device according to the first embodiment. FIG. 6 is a sequence diagram showing a first example of processing executed in the communication system according to the first embodiment. FIG. 7 is a sequence diagram showing a second example of processing executed in the communication system according to the first embodiment. FIG. 8 is a sequence diagram showing a third example of processing executed in the communication system according to the first embodiment. FIG. 9 is a sequence diagram showing a fourth example of processing executed in the communication system according to the first embodiment. FIG. 10 is a timing diagram comparing the operation of a comparative example with the operation of the first embodiment. FIG. 11 is a block diagram schematically showing the configuration of a communication system according to a second embodiment. FIG. 12 is a block diagram showing the schematic configuration of a roadside device according to the second embodiment.

[0013] Hereinafter, embodiments will be described with reference to the drawings. The following embodiments are merely examples, and various modifications are possible within the scope of the present disclosure.

[0014] 1 is a block diagram showing a schematic configuration of a communication system 100 according to embodiment 1. The communication system 100 includes a vehicle 110, a road side unit 130, and a server-side system 150.

[0015] The server-side system 150 includes a base station 151, a V2X application server 152, a Network Exposure Function (NEF) 153, a prediction device 154, and a V2X Application Enabler (VAE) server 155.

[0016] First, an outline of the conventional process for receiving QoS Sustainability will be described.

[0017] For example, the IQN sequence is described in chapter 6.4.1 of "3GPP TS 23.287 V18.1.0" described as Non-Patent Document 1. This sequence will be described with reference to FIG.

[0018] 2 is a sequence diagram of the first IQN as a comparative example. Here, it is assumed that processing is performed in a system including a vehicle 900, an operation and maintenance (OAM) 901, a network data analytical function (NWDAF) 902, a network element function (NEF) 903, and a V2X application server 904.

[0019] The V2X Application Server 904 collects information such as an IQN request, location information of the vehicle 900, requested QoS, and QoS threshold value from the vehicle 900 (S101).

[0020] The V2X Application Server 904 transmits the information collected in step S101 to the NEF 903 (S102). The NWDAF 902 receives the information via the NEF 903.

[0021] The NWDAF 902 predicts QoS based on the collected information in cooperation with the OAM (S103), and then transmits QoS Sustainability indicating the prediction result to the V2X Application Server 904 via the NEF 903 (S104).

[0022] The V2X Application Server 904 transmits the QoS Sustainability to the vehicle 900 (S105), which enables the vehicle 900 to perform V2X adaptation (S106).

[0023] The IQN sequence is also described in Chapter 5 of the following Non-Patent Document 2. This sequence will be explained using Figure 3. Non-Patent Document 2: 5GAA TR-200055, 2020

[0024] 3 is a sequence diagram of a second IQN as a comparative example. Here, it is assumed that processing is performed in a system including a V2X Application Client 910, a VAE Client 911, an NWDAF / NEF 912, a VAE Server 913, and a V2X Application Server 914. It is assumed that the V2X Application Client 910 and the VAE Client 911 are mounted on a vehicle 900.

[0025] The VAE Server 913 receives the QoS Sustainability (S110) and transmits the QoS Sustainability to the VAE Client 911 (S111).

[0026] The VAE Client 911 executes signal processing to make the QoS Sustainability processable within the vehicle 900 (S112).

[0027] The VAE Client 911 transmits the QoS Sustainability to the V2X Application Client 910 (S113), which enables the V2X Application Client 910 to perform V2X adaptation (S114).

[0028] In the process shown in FIGS. 2 and 3, the vehicle 900 receives the QoS Sustainability from the prediction device NWDAF 902 or NWDAF (Network Data Analytical Function) / NEF 912, so there is a large delay time until the QoS Sustainability is received.

[0029] Therefore, in the first embodiment, the roadside device 130 continuously collects the latest QoS Sustainability corresponding to each V2X service from the prediction device 154. Then, upon receiving a QoS prediction request from the vehicle 110, the roadside device 130 transmits the collected latest QoS Sustainability to the vehicle 110. This allows the vehicle 110 to receive the QoS Sustainability with low latency.

[0030] 1 includes a vehicle 110, a roadside device 130 arranged along a road on which the vehicle 110 travels, and a server-side system 150 as a prediction system that predicts the communication quality of a communication path from a V2X application server 152 as a service device that provides a V2X service to the vehicle 110 to the roadside device 130. The roadside device 130 sequentially transmits, at predetermined time intervals, to the server-side system 150 a prediction request requesting a prediction of communication quality, prediction information that is information necessary for the prediction, and location information that indicates the location of the roadside device 130. Each time the server-side system 150 receives a prediction request from the roadside device 130, the server-side system 150 predicts the communication quality using the prediction information and the location information that indicates the location of the roadside device 130, and sequentially transmits prediction results that are the results of the prediction to the roadside device 130. The roadside device 130 then stores the prediction results from the server-side system 150 in order, and when a prediction request is received from the vehicle 110, transmits the most recent stored prediction result to the vehicle 110. This will be explained in detail below.

[0031] The vehicle 110 transmits a QoS prediction request to the roadside unit 130. The QoS prediction request is information indicating a request for predicting communication quality.

[0032] Fig. 4 is a block diagram that schematically shows the configuration of a main part of vehicle 110 in embodiment 1. Note that Fig. 4 omits configuration that is necessary when vehicle 110 travels.

[0033] The vehicle 110 includes a V2X Application 111, a first wireless communication unit 112, and a second wireless communication unit 113.

[0034] The V2X Application 111 performs processing required on the vehicle 110 side to receive the V2X service. For example, the V2X Application 111 sends a QoS prediction request and prediction information to the nearest roadside device 130 via the first wireless communication unit 112. Note that the prediction information is, for example, the V2X service type and the identification number of the vehicle 110, and is information required to receive the V2X service.

[0035] Then, the V2X Application 111 receives QoS Sustainability from the nearest roadside device 130 via the first wireless communication unit 112 as a response to the QoS prediction request.

[0036] Furthermore, the V2X Application 111 performs V2X adaptation depending on the content of the QoS Sustainability from the roadside device 130.

[0037] The first wireless communication unit 112 is a PC5 interface that performs V2X communication via a PC5 reference point. Here, the first wireless communication unit 112 wirelessly communicates with the roadside device 130.

[0038] The second wireless communication unit 113 is a Uu interface that performs V2X communication via a Uu reference point. Here, the second wireless communication unit 113 communicates with the base station 151 by radio.

[0039] As shown in FIG. 5A , a part or all of the V2X Application 111 described above can be configured by, for example, a memory 10 and a processor 11 such as a CPU (Central Processing Unit) that executes a program stored in the memory 10. Such a program may be provided via a network or may be provided by being recorded on a recording medium. That is, such a program may be provided as, for example, a program product.

[0040] 5(B), a part or all of the V2X Application 111 may be configured by a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array). As described above, the V2X Application 111 can be realized by a processing circuit network.

[0041] Returning to FIG. 1, when the roadside device 130 receives a QoS prediction request from the vehicle 110 , it reads out the QoS Sustainability corresponding to the QoS prediction request from its own memory and transmits it to the vehicle 110 .

[0042] 6 is a block diagram showing a schematic configuration of the roadside device 130 according to the first embodiment. The roadside device 130 includes a first wireless communication unit 131 serving as a first communication unit, a V2X Application 132, a VAE Client 133, an information collection Proxy Server 134, a second wireless communication unit 135 serving as a second communication unit, a QoS Sustainability storage memory 136, and a read control unit 137.

[0043] The first wireless communication unit 131 is a Uu interface that performs V2X communication via a Uu reference point. Here, the first wireless communication unit 131 communicates with the base station 151 wirelessly. For example, the first wireless communication unit 131 sequentially transmits, at predetermined time intervals, to the server-side system 150, a prediction request that requests a prediction of communication quality, prediction information that is information necessary for the prediction, and location information that indicates the location of the roadside unit 130. Then, the first wireless communication unit 131 sequentially receives prediction results that are the results of the prediction from the server-side system 150 in response to the prediction request.

[0044] The V2X Application 132 performs processing required on the roadside device 130 side so that the vehicle 110 can receive the V2X service. For example, the V2X Application 132 provides the VAE Client 133 with an IQN request as a prediction request, prediction information, location information of the roadside device 130, and a time interval Tint for periodically transmitting this information. Here, examples of the prediction information include the V2X service type related to the IQN, the requested QoS, the QoS prediction period, and the QoS threshold value when notifying the IQN. The QoS prediction period may also be expressed as prediction timing.

[0045] The V2X Application 132 is a set of applications for each V2X service type, and is composed of, for example, a first RSU V2X Application 132-1, a second RSU V2X Application 132-2, ..., an n-th RSU V2X Application 132-n, as shown in Fig. 6. Each of the first RSU V2X Application 132-1, the second RSU V2X Application 132-2, ..., the n-th RSU V2X Application 132-n provides the VAE Client 133 with an IQN request, prediction information, location information of the roadside device 130, and the time interval Tint for periodically transmitting this information.

[0046] The VAE Client 133 provides the information from the V2X Application 132 to the information collection Proxy Server 134, and also acquires the corresponding QoS Sustainability from the information collection Proxy Server 134 and stores the QoS Sustainability in the QoS Sustainability storage memory 136.

[0047] Upon receiving the IQN request, the prediction information, the location information of the roadside device 130, and the time interval Tint from the VAE Client 133, the information collection Proxy Server 134 periodically transmits the IQN request, the prediction information, and the location information to the V2X application server 152 via the first wireless communication unit 131 at the time interval Tint. Then, the information collection Proxy Server 134 receives the QoS Sustainability via the first wireless communication unit 131 in response to the IQN request, and provides the QoS Sustainability to the VAE Client 133.

[0048] The second wireless communication unit 135 is a PC5 interface that performs V2X communication via a PC5 reference point. Here, the second wireless communication unit 135 wirelessly communicates with the vehicle 110. For example, the second wireless communication unit 135 receives a QoS prediction request from the vehicle 110.

[0049] The QoS Sustainability storage memory 136 is a storage unit that stores the QoS Sustainability collected as described above.

[0050] When the read control unit 137 receives a QoS prediction request from the vehicle 110 via the second wireless communication unit 135, it reads the QoS Sustainability corresponding to the QoS prediction request from the QoS Sustainability storage memory 136 and sends the read QoS Sustainability to the vehicle 110 via the second wireless communication unit 135.

[0051] As shown in FIG. 5A , part or all of the read control unit 137, V2X Application 132, VAE Client 133, and information collection Proxy Server 134 described above can be configured by, for example, a memory 10 and a processor 11 such as a CPU that executes a program stored in the memory 10. Such a program may be provided via a network or may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a program product.

[0052] Furthermore, some or all of the above-described read control unit 137, V2X Application 132, VAE Client 133, and information collection Proxy Server 134 can be configured by the processing circuitry 12, such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC, or an FPGA, as shown in Fig. 5(B) . As described above, the above-described read control unit 137, V2X Application 132, VAE Client 133, and information collection Proxy Server 134 can be realized by a processing circuitry.

[0053] 1 , the base station 151 is a wireless base station that performs wireless communication. The base station 151 transmits an IQN request, prediction information, and location information from the roadside device 130 to the V2X application server 152.

[0054] Then, the base station 151 receives the QoS Sustainability from the VAE server 155 as a response to the IQN request, and transmits the QoS Sustainability to the roadside unit 130 .

[0055] In addition, the base station 151 relays the V2X service provided to the vehicle 110 from the V2X application server 152.

[0056] The V2X application server 152 is a service device that provides a V2X service. Here, the V2X application server 152 provides the V2X service to the vehicle 110. The V2X application server 152 may be a real server or a virtual server.

[0057] When the V2X application server 152 receives the IQN request, the prediction information, and the location information, it transmits the IQN request, the prediction information, and the location information to the prediction device 154 via the NEF 153.

[0058] The NEF 153 is a device that exposes network functions constituting 5GC to the outside. The NEF 153 may be realized by a single device. The NEF 153 may also be included in the prediction device 154.

[0059] The prediction device 154 is a device that executes NWDAF. The prediction device 154 receives an IQN request, prediction information, and location information. The prediction device 154 predicts QoS based on the prediction information and location information. For example, the prediction device 154 predicts the QoS of a communication path from the V2X application server 152 to the roadside device 130. The QoS content includes the error rate, delay, bit rate, etc. of the communication path. The prediction device 154 transmits QoS Sustainability, which is the QoS prediction result, to the roadside device 130.

[0060] The VAE server 155 is a device that, together with the VAE client 911, mediates communication between the prediction device 154 that executes the NWDAF and the V2X Application 111. Here, the VAE server 155 transmits the QoS Sustainability from the NEF 153 to the base station 151.

[0061] Next, the processing executed in the communication system 100 according to the first embodiment will be described using the sequence diagrams shown in Figures 7 to 11. In Figures 7 to 11, the base station 151 and the NEF 153 are omitted because they simply relay information. Figure 7 is a sequence diagram showing a first example of the processing executed in the communication system 100 according to the first embodiment.

[0062] The V2X Application 111 of the vehicle 110 that desires the V2X service registers the V2X service with the V2X application server 152 via the second wireless communication unit 113 (S10). Then, the V2X application server 152 provides the V2X service to the vehicle 110 via the base station 151. The V2X Application 111 of the vehicle 110 receives the V2X service via the second wireless communication unit 113 (S11).

[0063] The V2X Application 132 of the roadside device 130 provides the information collection Proxy Server 134 via the VAE Client 133 with an IQN request, prediction information, location information of the roadside device 130, and the time interval Tint for periodically transmitting this information (S12). For example, the prediction information is information indicating the V2X service type related to the IQN, the requested QoS, the QoS prediction period, and the QoS threshold value when notifying the IQN. The QoS prediction period may also be expressed as prediction timing.

[0064] When the information collection proxy server 134 of the roadside device 130 receives the IQN request, the prediction information, the location information, and the time interval Tint from the V2X application 132, the information collection proxy server 134 periodically transmits the IQN request, the prediction information, and the location information to the V2X application server 152 via the first wireless communication unit 131 and the base station 151 at the time interval Tint (S13).

[0065] 8 is a sequence diagram showing a second example of processing executed in the communication system 100 according to embodiment 1. Every time the V2X application server 152 receives an IQN request, prediction information, and location information from the information collection proxy server 134 of the roadside device 130 at a time interval Tint (S20), the V2X application server 152 transmits the IQN request, prediction information, and location information to the prediction device 154 via the NEF 153 (S21).

[0066] FIG. 9 is a sequence diagram showing a third example of the processing executed in the communication system 100 according to the first embodiment.

[0067] When the prediction device 154 receives an IQN request, prediction information, and location information from the V2X application server 152 (S30), it predicts the QoS of the communication path from the V2X application server 152 to the roadside device 130 based on the prediction information, location information, etc. (S31).

[0068] The prediction device 154 transmits the QoS Sustainability, which is the QoS prediction result, to the VAE server 155 via the NEF 153 (S32).

[0069] The VAE server 155 performs signal processing on the QoS Sustainability to match the API (S33), and then transmits the QoS Sustainability to the VAE Client 133 of the roadside unit 130 via the base station 151 (S34).

[0070] The above processing from steps S31 to S34 is repeated at a time interval Tint each time the prediction device 154 receives an IQN request, prediction information, and location information from the V2X Application server.

[0071] 10 is a sequence diagram showing a fourth example of processing executed in the communication system 100 according to the first embodiment. The first wireless communication unit 131 of the roadside device 130 receives the QoS Sustainability from the base station 151 (S40). The received QoS Sustainability is provided to the VAE Client 133 via the information collection Proxy Server 134.

[0072] The VAE Client 133 of the roadside device 130 executes signal processing on the QoS Sustainability so that the V2X Application 111 of the vehicle 110 can process the QoS Sustainability (S41).

[0073] Then, the VAE Client 133 stores the processed QoS Sustainability in the QoS Sustainability storage memory 136 (S42).

[0074] The processes of steps S41 and S42 are repeated at time intervals Tint every time the VAE Client 133 receives QoS Sustainability. In step S42, the QoS Sustainability is stored in the QoS Sustainability storage memory 136, and the QoS Sustainability storage memory 136 always stores the latest QoS Sustainability.

[0075] 11 is a sequence diagram showing a fifth example of processing executed in the communication system 100 according to the first embodiment. The V2X Application 111 of the vehicle 110 transmits a QoS prediction request and prediction information to the nearest roadside device 130 via the first wireless communication unit 112 (S50). Note that the prediction information is information indicating, for example, the V2X service type and the identification number of the vehicle 110.

[0076] The read control unit 137 of the roadside device 130 receives the QoS prediction request and the prediction information from the vehicle 110 via the second wireless communication unit 135, and reads the latest QoS Sustainability corresponding to the V2X service type provided to the vehicle 110 from the QoS Sustainability storage memory 136 in accordance with the QoS prediction request and the prediction information (S51).

[0077] Then, the read control unit 137 transmits the read QoS Sustainability to the vehicle 110 via the second wireless communication unit 135 (S52).

[0078] The V2X Application 111 of the vehicle 110 receives the QoS Sustainability from the roadside device 130 via the first wireless communication unit 112, and performs V2X adaptation according to the content of the QoS Sustainability (S53).

[0079] Next, the timing from when the vehicle 110 issues an IQN request or a QoS prediction request until when it receives the QoS Sustainability will be described with reference to Fig. 12, which is a timing diagram comparing the operation of the comparative example shown in Figs. 2 and 3 with the operation of the first embodiment. Fig. 12 shows both the timing of the comparative example and the timing of the first embodiment.

[0080] In the comparative example, the vehicle 900 transmits an IQN request at time Tv, and receives the QoS Sustainability after time Td1 via the sequence shown in Fig. 2 or 3. The QoS prediction period 170 requested by the vehicle 900 is a section of time interval T after time Tf1 has elapsed from time Tv. This QoS prediction period 170 is specific to the V2X service and is a prediction period that is a period defined by the V2X service.

[0081] In the above comparative example, since the QoS Sustainability cannot be received at a timing earlier than the time Td1, the time Tf1 must be a value greater than the time Td1. Therefore, a QoS prediction cannot be requested at a timing earlier than the time Td1. Furthermore, if the difference between the time Tf1 and the time Td1 is small, the time allowance Tad1 (= Tf1 - Td1) until the vehicle 900 executes the V2X application becomes small, which creates a risk that the V2X application cannot be executed properly.

[0082] In the operation of the first embodiment, the roadside device 130 transmits the IQN request at time intervals Tint. In the example of Fig. 12, it is assumed that the IQN requests are transmitted at times T1, T2, T3, ..., Tn, Tn+1, Tn+2, Tn+3, ....

[0083] Also, the delay time from when the roadside device 130 transmits an IQN request until when it receives the QoS Sustainability corresponding to the IQN request is Td1#. Furthermore, the vehicle 110 receives the QoS Sustainability a time Td2 after transmitting the QoS prediction request at time Tv.

[0084] The QoS prediction period 171 for the IQN request from the roadside device 130 is set to a time interval T+Tint after the time Tf1+Td1# has elapsed from the timing of issuing the IQN request.

[0085] The QoS prediction period 171 is advanced by up to Tint relative to the QoS prediction period 170, but by setting Tint to a value smaller than the allowable prediction error τ, which is the allowable prediction error, it becomes possible to perform QoS prediction within the allowable error of the prediction period. Normally, a certain degree of error is allowed for the QoS prediction period, and it is often preferable from a safety perspective to set the time width to a larger value. Therefore, the time interval of the QoS prediction period 171 is set to T+Tint.

[0086] The time Td1# is a value equivalent to the time Td1 in the comparative example. The time Td1# varies depending on the location of the roadside device 130 or the congestion state of the communication system 100, but an average value stored in advance in the roadside device 130 may be used. Alternatively, the amount of delay may be measured each time an IQN request is made using a timestamp or the like, and the most recent measurement value may be used as the time Td1#.

[0087] 12 , in the operation of the first embodiment, the roadside device 130 receives the QoS Sustainability corresponding to the IQN request transmitted at time T2 at time T2+Td1#. Therefore, when the vehicle 110 transmits a QoS prediction request at time Tv, the roadside device 130 transmits the QoS Sustainability corresponding to the IQN request transmitted at time T2 at time Tv+Td2. However, because the vehicle 110 and the roadside device 130 communicate directly in nearby locations, the time at which the vehicle 110 receives the QoS Sustainability is also assumed to be the same as time Tv+Td2.

[0088] In the first embodiment, the sequence from when the vehicle 110 transmits the QoS prediction request to when it receives the QoS Sustainability includes only two steps, as shown in FIG. 11 . Therefore, the time Td2 is much smaller than the time Td1 in the comparative example. Therefore, the time margin Tad2 from when the vehicle 110 receives the QoS Sustainability to the start of the QoS prediction period is larger than the time margin Tad1 in the comparative example, and a sufficient time width can be secured for performing V2X adaptation operation.

[0089] As described above, since the time Td2 is much smaller than the time Td1, the time margin Tad2 required for performing the V2X adaptation operation can be secured, and the time Tf until the start of the prediction period can be set to Tf2, which is smaller than the time Tf1. In Fig. 12, the QoS prediction period in this case is shown as QoS prediction period 172.

[0090] 13 is a block diagram showing a schematic configuration of a communication system 200 according to embodiment 2. The communication system 200 includes a vehicle 210, a roadside device 230, and a server-side system 150.

[0091] In the first embodiment, the vehicle 110 receives the V2X service via the base station 151, but in the second embodiment, the vehicle 210 receives the V2X service via the roadside device 230. For example, in the second embodiment, the vehicle 210 performs vehicle-side prediction, which is a prediction of the communication quality of the communication path between the vehicle 210 and the roadside device 230. Then, the vehicle 210 receives the V2X service via the roadside device 230 in accordance with the prediction result from the roadside device 230 and the result of the vehicle-side prediction.

[0092] The QoS Sustainability collected by the roadside device 230 is the communication quality of the communication path from the V2X application server 152 to the roadside device 230. When receiving a V2X service via the roadside device 230, the vehicle 210 needs not only the QoS Sustainability but also the predicted result of the communication quality between the roadside device 230 and the vehicle 210. This will be described below.

[0093] Fig. 14 is a block diagram that schematically shows the configuration of a main part of a vehicle 210 in embodiment 2. Note that Fig. 14 also omits configuration that is necessary when vehicle 210 travels.

[0094] The vehicle 210 includes a V2X Application 211, a first wireless communication unit 112, a second wireless communication unit 113, an interface monitoring unit 214, and an interface QoS prediction unit 215. The first wireless communication unit 112 and the second wireless communication unit 113 of the vehicle 210 in the second embodiment are similar to the first wireless communication unit 112 and the second wireless communication unit 113 of the vehicle 110 in the first embodiment.

[0095] The V2X Application 211 performs processing required on the vehicle 210 side to receive the V2X service. For example, the V2X Application 211 transmits a QoS prediction request and prediction information to the nearest roadside device 230 via the first wireless communication unit 112.

[0096] Then, the V2X Application 211 receives QoS Sustainability from the nearest roadside device 230 via the first wireless communication unit 112 as a response to the QoS prediction request.

[0097] In addition, the V2X Application 211 provides a QoS prediction request and prediction information to the interface QoS prediction unit 215.

[0098] Then, the V2X Application 211 receives, from the interface QoS prediction unit 215, a PC5 QoS prediction result that is a prediction result of the QoS between the first wireless communication unit 112 and the nearest roadside unit 230.

[0099] The V2X Application 211 executes V2X adaptation in accordance with the content of QoS Sustainability from the roadside device 230 and the PC5 prediction result from the interface QoS prediction unit 215. However, unlike in the first embodiment, when executing V2X adaptation, the V2X Application 211 receives the provision of a V2X service via the first wireless communication unit 112 and the roadside device 230.

[0100] The interface monitoring unit 214 constantly monitors the communication quality between the first wireless communication unit 112 and the roadside unit 230. In this case, the first wireless communication unit 112 and the roadside unit 230 perform wireless communication via the PC 5, and therefore the interface monitoring unit 214 monitors the communication quality of the PC 5. The interface monitoring unit 214 then provides the monitoring result to the interface QoS prediction unit 215.

[0101] The interface QoS prediction unit 215 performs QoS prediction for PC5 based on the QoS prediction request from the V2X Application 111 and the prediction information, and provides the prediction result, that is, the PC5 QoS prediction result, to the V2X Application 211.

[0102] As shown in FIG. 5A, part or all of the interface monitoring unit 214 and interface QoS prediction unit 215 described above can be configured with a memory 10 and a processor 11 such as a CPU that executes a program stored in the memory 10. Such a program may be provided over a network or may be provided by being recorded on a recording medium. That is, such a program may be provided as a program product, for example.

[0103] 5B, the interface monitoring unit 214 and the interface QoS prediction unit 215 may be partially or entirely configured by a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC, or an FPGA. As described above, the interface monitoring unit 214 and the interface QoS prediction unit 215 may be realized by a processing circuit network.

[0104] 15 is a block diagram showing a schematic configuration of a roadside device 230 according to embodiment 2. The roadside device 230 includes a first wireless communication unit 131, a V2X Application 132, a VAE Client 133, an information collection Proxy Server 134, a second wireless communication unit 135, a QoS Sustainability storage memory 136, a read control unit 137, and a relay unit 238.

[0105] The second wireless communication unit 135, the QoS Sustainability storage memory 136, the read control unit 137, the first wireless communication unit 131, the V2X Application 132, the VAE Client 133, and the information collection Proxy Server 134 of the roadside device 230 in the second embodiment are similar to the second wireless communication unit 135, the QoS Sustainability storage memory 136, the read control unit 137, the first wireless communication unit 131, the V2X Application 132, the VAE Client 133, and the information collection Proxy Server 134 of the roadside device 130 in the first embodiment.

[0106] When the first wireless communication unit 131 receives a V2X service, the relay unit 238 sends the V2X service from the second wireless communication unit 135 to the vehicle 210.

[0107] 5A, a part or all of the relay unit 238 described above can be configured by a memory 10 and a processor 11 such as a CPU that executes a program stored in the memory 10. Such a program may be provided over a network or may be provided by being recorded on a recording medium. That is, such a program may be provided as a program product, for example.

[0108] 5B, a part or all of the relay unit 238 described above can be configured by a processing circuit 12 such as a single circuit, a composite circuit, a programmable processor, a programmable parallel processor, an ASIC, or an FPGA. As described above, the relay unit 238 described above can be realized by a processing circuit network.

[0109] 13 , the base station 251 is a wireless base station that performs wireless communication. The base station 251 transmits the IQN request, the prediction information, and the location information from the roadside device 230 to the V2X application server 152.

[0110] Then, the base station 251 receives the QoS Sustainability from the VAE server 155 as a response to the IQN request, and transmits the QoS Sustainability to the roadside unit 230 .

[0111] In addition, the base station 251 relays the V2X service provided to the vehicle 210 from the V2X application server 152 via the roadside device 230.

[0112] As described above, according to the second embodiment, the vehicle 210 can receive the V2X service via the roadside device 230. In this case, the vehicle 210 does not need to include the second wireless communication unit 113.

[0113] 100, 200 Communication system, 110, 210 Vehicle, 111, 211 V2X Application, 112 First wireless communication unit, 113 Second wireless communication unit, 214 Interface monitoring unit, 215 Interface QoS prediction unit, 130, 230 Roadside device, 131 First wireless communication unit, 132 V2X Application, 133 VAE Client, 134 Information collection Proxy Server, 135 Second wireless communication unit, 136 QoS Sustainability storage memory, 137 Read control unit, 238 Relay unit, 150 Server side system, 151 Base station, 152 V2X application server, 153 NEF, 154 prediction device, 155 VAE server.

Claims

1. A communication system comprising a vehicle, a roadside device arranged along a road on which the vehicle travels, and a prediction system that predicts the communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, wherein the roadside device sequentially transmits a prediction request for requesting the prediction of the communication quality, prediction information that is information necessary for the prediction, and position information indicating the position of the roadside device to the prediction system at a predetermined time interval, the prediction system executes the prediction of the communication quality using the prediction information and the position information every time it receives the prediction request, and sequentially transmits a prediction result that is a result of the prediction to the roadside device, and the roadside device sequentially stores the prediction result and, when receiving a prediction request from the vehicle, transmits the latest stored prediction result to the vehicle. A communication system characterized by the above.

2. The prediction information includes a prediction period that is a period defined in the V2X service, wherein the start timing of the prediction period is later than the timing when a delay time from when the roadside device transmits the prediction request until it receives the corresponding prediction result has elapsed. The communication system according to claim 1, characterized by the above.

3. The delay time is predetermined. The communication system according to claim 2, characterized by the above.

4. The roadside device sequentially measures the delay time and calculates the start timing of the prediction period using the latest delay time. The communication system according to claim 2, characterized by the above.

5. The prediction information includes a prediction period, wherein the prediction period is a period obtained by adding the predetermined time interval to the period defined in the V2X service. The communication system according to claim 1, characterized by the above.

6. The predetermined time interval is shorter than an error allowed as an error of the prediction. The communication system according to any one of claims 1 to 5, characterized by the above.

7. The vehicle performs a vehicle-side prediction that is a prediction of the communication quality of a communication path between the vehicle and the roadside device, and receives the V2X service via the roadside device according to the prediction result from the roadside device and the result of the vehicle-side prediction. The communication system according to any one of claims 1 to 6, characterized by the above.

8. A roadside device arranged along a road on which a vehicle travels, comprising: a first communication unit that sequentially transmits a prediction request for predicting the communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, prediction information that is information necessary for the prediction, and position information indicating the position of the roadside device to a prediction system that predicts the communication quality at a predetermined time interval, and sequentially receives, as a response to the prediction request, a prediction result that is the result of the prediction from the prediction system; a storage unit that stores the prediction result; a second communication unit that receives a prediction request from the vehicle; and a read control unit that, when the prediction request from the vehicle is received, reads out the latest stored prediction result and causes the read prediction result to be transmitted to the vehicle via the second communication unit.

9. A program that causes a computer to function as a roadside device arranged along a road on which a vehicle travels, the program causing the computer to function as: a first communication unit that sequentially transmits a prediction request for predicting the communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, prediction information that is information necessary for the prediction, and position information indicating the position of the roadside device to a prediction system that predicts the communication quality at a predetermined time interval, and sequentially receives, as a response to the prediction request, a prediction result that is the result of the prediction from the prediction system; a storage unit that stores the prediction result; a second communication unit that receives a prediction request from the vehicle; and a read control unit that, when the prediction request from the vehicle is received, reads out the latest stored prediction result and causes the read prediction result to be transmitted to the vehicle via the second communication unit.

10. A communication method performed by a roadside device arranged along a road on which a vehicle travels, the method comprising: sequentially transmitting, at a predetermined time interval, a prediction request for predicting the communication quality of a communication path from a service device that provides a V2X service to the vehicle to the roadside device, prediction information that is information necessary for the prediction, and position information indicating the position of the roadside device to a prediction system that predicts the communication quality; sequentially receiving, as a response to the prediction request, a prediction result that is a result of the prediction from the prediction system; storing the prediction result; receiving a prediction request from the vehicle; when the prediction request from the vehicle is received, reading out the latest stored prediction result; and transmitting the read prediction result to the vehicle.

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