Communication systems, roadside equipment, programs, and communication methods

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

[Technical Field]

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

[0002] Remote driving, automatic driving, automatic parking, and the like are known as V2X (Vehicle to X) services. To implement V2X services, QoS (Quality of Service) is predicted. By notifying a vehicle of QoS Sustainability which is the prediction result, the vehicle can take actions such as stopping traveling, decelerating, or steering operation before QoS deteriorates. The notification is also referred to as IQN (In-advance QoS Notification). The action is also referred to as V2X adaptation.

[0003] QoS Sustainability is requested from a vehicle to a server, whereby the QoS at the position of the vehicle is predicted and transmitted from the server to the vehicle (see, for example, Non-Patent Document 1). [Prior Art Documents] [Non-Patent Documents]

[0004] [Non-Patent Document 1] 3GPP TS 23.287 V18.1.0, 2023 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, since a vehicle must go through the sequence described in Non-Patent Document 1, etc., in order to receive QoS Sustainability, the delay time until the vehicle receives QoS Sustainability becomes larger than the allowable delay time for receiving QoS Sustainability in the V2X application, which presents a problem of delays in V2X adaptation.

[0006] Therefore, one or more aspects of this disclosure aim to reduce the delay in a vehicle receiving QoS Sustainability. [Means for solving the problem]

[0007] A communication system according to one aspect of the present disclosure is 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 V2X services to the vehicle to the roadside device, wherein the roadside device sequentially transmits a prediction request requesting the prediction of the communication quality, prediction information which is information necessary for the prediction, and location information indicating the location of the roadside device at predetermined time intervals, the prediction system, each time it receives a prediction request, performs the prediction of the communication quality using the prediction information and the location information, and sequentially transmits the prediction result which is the result of the prediction to the roadside device, 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 arranged along a road on which a vehicle travels, and is characterized by comprising: a first communication unit that sequentially transmits to a prediction system that predicts the communication quality of a communication path from a service device that provides V2X services to the vehicle, at predetermined time intervals, a prediction request requesting the prediction of the communication quality, prediction information which is information necessary for the prediction, and location information indicating the location of the roadside device, and sequentially receives from the prediction system, as a response to the prediction request, a prediction result which is the result of the prediction; 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 a prediction request is received from the vehicle, reads 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 positioned along a road on which a vehicle travels, and the computer is characterized in that it functions as a first communication unit that sequentially transmits to a prediction system that predicts the communication quality of a communication path from a service device that provides V2X services to the vehicle to the roadside device at predetermined time intervals, a prediction request that requests the prediction of the communication quality, prediction information which is information necessary for the prediction, and location information indicating the location of the roadside device, and sequentially receives prediction results which are the result of the prediction from the prediction system as a response to the prediction request, a storage unit that stores the prediction results, a second communication unit that receives prediction requests from the vehicle, and a read control unit that, when a prediction request is received from the vehicle, reads 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, characterized in that, at predetermined time intervals, the roadside device sequentially transmits to a prediction system that predicts the communication quality of a communication path from a service device that provides V2X services to the vehicle to the roadside device a prediction request for the communication quality, prediction information which is information necessary for the prediction, and location information indicating the location of the roadside device to the prediction system, sequentially receives prediction results which are the result of the prediction as a response to the prediction request, stores the prediction results, receives a prediction request from the vehicle, reads out the latest stored prediction result when a prediction request is received from the vehicle, and transmits the read prediction result to the vehicle. [Effects of the Invention]

[0011] According to one or more aspects of this disclosure, the delay in a vehicle receiving QoS Sustainability can be reduced. [Brief explanation of the drawing]

[0012] [Figure 1] This is a block diagram that schematically shows the configuration of the communication system according to Embodiment 1. [Figure 2] This is a sequence diagram of the first IQN as a comparative example. [Figure 3] This is a sequence diagram of the second IQN as a comparative example. [Figure 4] This is a block diagram schematically showing the main components of the vehicle in Embodiment 1. [Figure 5] (A) and (B) are block diagrams showing hardware configuration examples. [Figure 6] This is a block diagram showing the schematic configuration of the roadside device according to Embodiment 1. [Figure 7] This is a sequence diagram showing a first example of processing performed in the communication system of Embodiment 1. [Figure 8] This is a sequence diagram showing a second example of processing performed in the communication system according to Embodiment 1. [Figure 9] It is a sequence diagram showing a third example of processing executed by the communication system according to the first embodiment. [Figure 10] It is a sequence diagram showing a fourth example of processing executed by the communication system according to the first embodiment. [Figure 11] It is a sequence diagram showing a fifth example of processing executed by the communication system according to the first embodiment. [Figure 12] It is a timing diagram comparing an operation as a comparative example with the operation of the first embodiment. [Figure 13] It is a block diagram schematically showing a configuration of a communication system according to the second embodiment. [Figure 14] It is a block diagram schematically showing a configuration of main parts of a vehicle in the second embodiment. [Figure 15] It is a block diagram showing a schematic configuration of a roadside device according to the second embodiment. DETAILED DESCRIPTION OF EMBODIMENTS

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

[0014] First Embodiment. FIG. 1 is a block diagram schematically showing a configuration of a communication system 100 according to the first embodiment. 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, let's explain the overview of the conventional process for receiving QoS Sustainability.

[0017] For example, in "3GPP TS 23.287 V18.1.0," which is listed as Non-Patent Document 1, the sequence of IQNs is described in Chapter 6.4.1. This sequence will be explained using Figure 2.

[0018] Figure 2 is a sequence diagram of the first IQN as a comparative example. Here, processing is assumed to be performed by a system including Vehicle 900, OAM (Operation and Maintenance) 901, NWDAF (Network Data Analytic Function) 902, NEF 903, and V2X Application Server 904.

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

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

[0021] Based on the collected information, the NWDAF902 works in conjunction with OAM to predict QoS (S103). Then, NWDAF902 sends the QoS Sustainability, which indicates the result of the prediction, to V2X Application Server904 via NEF903 (S104).

[0022] The V2X Application Server 904 sends its QoS Sustainability to the vehicle 900 (S105). As a result, vehicle 900 can perform V2X adaptation (S106).

[0023] Furthermore, Chapter 5 of Non-Patent Document 2, listed below, also describes the IQN sequence. This sequence will be explained using Figure 3. Non-Patent Document 2:5GAA TR-200055, 2020

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

[0025] VAE Server913 receives QoS Sustainability (S110). VAE Server 913 sends QoS Sustainability to VAE Client 911 (S111).

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

[0027] The VAE Client 911 sends QoS Sustainability to the V2X Application Client 910 (S113). This allows the V2X Application Client 910 to perform V2X adaptation (S114).

[0028] In the processes shown in Figures 2 and 3, the vehicle 900 receives QoS Sustainability from the prediction device NWDAF902 or NWDAF (Network Data Analytic Function) / NEF912, resulting in a large delay time until QoS Sustainability is received.

[0029] Therefore, in Embodiment 1, the roadside device 130 continuously collects the latest QoS sustainability corresponding to each V2X service from the prediction device 154. When it receives a QoS prediction request from the vehicle 110, the roadside device 130 transmits the collected latest QoS sustainability to the vehicle 110. As a result, the vehicle 110 can receive the QoS sustainability with low latency.

[0030] For example, the communication system 100 shown in Figure 1 includes a vehicle 110, roadside equipment 130 positioned along the road on which the vehicle 110 travels, and a server-side system 150 as a prediction system that predicts the communication quality of the communication path from a V2X application server 152, which is a service device that provides V2X services to the vehicle 110, to the roadside equipment 130. The roadside device 130 sequentially transmits a prediction request requesting a prediction of communication quality, prediction information necessary for that prediction, and location information indicating the location of the roadside device 130 to the server-side system 150 at predetermined time intervals. Each time the server-side system 150 receives a prediction request from the roadside device 130, it uses the received prediction information and location information indicating the location of the roadside device 130 to perform a prediction of the communication quality, and sequentially transmits the prediction result to the roadside device 130. The roadside device 130 then sequentially stores the prediction results from the server-side system 150, and when it receives a prediction request from a vehicle 110, it transmits the latest stored prediction result to that vehicle 110. The details are explained below.

[0031] Vehicle 110 transmits a QoS prediction request to roadside device 130. The QoS prediction request is information indicating a request for a prediction of communication quality.

[0032] Figure 4 is a block diagram schematically showing the main components of the vehicle 110 in Embodiment 1. Note that Figure 4 omits the components necessary for vehicle 110 to operate.

[0033] Vehicle 110 comprises a V2X Application 111, a first wireless communication unit 112, and a second wireless communication unit 113.

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

[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, V2X Application 111 performs V2X adaptation according to the QoS Sustainability information from the roadside device 130.

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

[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 using wireless technology.

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

[0040] Furthermore, part or all of the V2X Application 111 can also be composed of processing circuits 12 such as a single circuit, a composite circuit, a programmable processor, a programmable parallel processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array), as shown in Figure 5(B). As described above, V2X Application 111 can be implemented using a processing network.

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

[0042] Figure 6 is a block diagram showing the schematic configuration of the roadside device 130 according to Embodiment 1. The roadside device 130 includes a first wireless communication unit 131 as a first communication unit, a V2X Application 132, a VAE Client 133, an information gathering proxy server 134, a second wireless communication unit 135 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 using wireless technology. For example, the first wireless communication unit 131 sequentially transmits to the server-side system 150, at predetermined time intervals, a prediction request requesting a prediction of communication quality, prediction information necessary for that prediction, and location information indicating the location of the roadside device 130. Then, the first wireless communication unit 131 sequentially receives the prediction results, which are the results of the prediction, from the server-side system 150 as a response to the prediction request.

[0044] The V2X Application 132 performs the necessary processing on the roadside device 130 side so that the vehicle 110 can receive V2X services. For example, V2X Application 132 provides 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. Examples of prediction information include the V2X service type related to the IQN, the requested QoS, the QoS prediction period, and the QoS threshold when notifying the IQN. The QoS prediction period may also be expressed as the prediction timing.

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

[0046] The VAE Client 133 provides information from the V2X Application 132 to the Information Collection Proxy Server 134, and also obtains the corresponding QoS Sustainability from the Information Collection Proxy Server 134 and stores that QoS Sustainability in the QoS Sustainability Storage Memory 136.

[0047] When the information gathering proxy server 134 receives an IQN request, prediction information, location information of the roadside device 130, and a time interval Tint from the VAE client 133, it periodically sends the IQN request, prediction information, and location information to the V2X application server 152 via the first wireless communication unit 131 at the time interval Tint. Then, the Information Gathering Proxy Server 134 receives the QoS Sustainability via the first wireless communication unit 131 as a response to the IQN request and provides that QoS Sustainability to the VAE Client 133.

[0048] The second wireless communication unit 135 is a PC5 interface that performs V2X communication via the PC5 reference point. Here, the second wireless communication unit 135 communicates with the vehicle 110 using wireless technology. 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 readout 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 readout QoS Sustainability to the vehicle 110 via the second wireless communication unit 135.

[0051] Some 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, for example, with a memory 10 and a processor 11 such as a CPU that executes the program stored in the memory 10, as shown in Figure 5(A). Such a program may be provided via a network or 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 Read Control Unit 137, V2X Application 132, VAE Client 133, and Information Collection Proxy Server 134 described above can also be composed of processing circuits 12 such as a single circuit, a composite circuit, a program-operated processor, a program-operated parallel processor, an ASIC, or an FPGA, as shown in Figure 5(B). As described above, the read control unit 137, V2X Application 132, VAE Client 133, and information collection proxy server 134 can be implemented by a processing circuit network.

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

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

[0055] Furthermore, the base station 151 relays the V2X service that the vehicle 110 receives from the V2X application server 152.

[0056] The V2X application server 152 is a service device that provides V2X services. In this case, the V2X application server 152 provides V2X services to the vehicle 110. The V2X application server 152 may be a physical server or a virtual server.

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

[0058] The NEF153 is a device that exposes the network functions that make up 5GC to the outside world. NEF153 may be implemented in a single device. Alternatively, NEF153 may be included in the prediction device 154.

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

[0060] The VAE server 155, along with the VAE client 911, is a device that mediates communication between the prediction device 154, which performs 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 processes executed by the communication system 100 according to Embodiment 1 will be explained using the sequence diagrams shown in Figures 7 to 11. In Figures 7 to 11 below, base station 151 and NEF 153 are omitted because they are simply relaying information. Figure 7 is a sequence diagram showing a first example of processing performed by the communication system 100 of Embodiment 1.

[0062] The V2X Application 111 of the vehicle 110 that wishes to use the V2X service registers the V2X service with the V2X application server 152 via the second wireless communication unit 113 (S10). The V2X application server 152 then 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 a time interval Tint for periodically transmitting this information (S12). For example, the prediction information includes information such as the V2X service type related to the IQN, the requested QoS, the QoS prediction period, and the QoS threshold when notifying the IQN. The QoS prediction period may also be expressed as the prediction timing.

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

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

[0066] Figure 9 is a sequence diagram showing a third example of processing performed by the communication system 100 according to Embodiment 1.

[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 and location information (S31).

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

[0069] The VAE server 155 performs signal processing for QoS Sustainability to synchronize APIs (S33). Then, the VAE server 155 transmits QoS Sustainability to the VAE Client 133 of the roadside device 130 via the base station 151 (S34).

[0070] The processes described in steps S31 to S34 above are repeated at time intervals of Tint each time the prediction device 154 receives an IQN request, prediction information, and location information from the V2X Application server.

[0071] Figure 10 is a sequence diagram showing a fourth example of processing performed by the communication system 100 according to Embodiment 1. The first wireless communication unit 131 of the roadside device 130 receives QoS Sustainability from the base station 151 (S40). The received QoS Sustainability is provided to the VAE Client 133 via the information gathering proxy server 134.

[0072] The VAE Client 133 of the roadside device 130 performs signal processing on QoS Sustainability in order to enable the V2X Application 111 of the vehicle 110 to process 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 in steps S41 and S42 are repeated every time the VAE Client 133 receives a QoS Sustainability, with a time interval of Tint. In step S42, the QoS Sustainability is stored in the QoS Sustainability storage memory 136, and the QoS Sustainability storage memory 136 always contains the latest QoS Sustainability.

[0075] Figure 11 is a sequence diagram showing a fifth example of processing performed by the communication system 100 according to Embodiment 1. The V2X Application 111 of vehicle 110 transmits a QoS prediction request and prediction information to the nearest roadside device 130 via the first wireless communication unit 112 (S50). The prediction information includes, for example, information indicating the V2X service type and the identification number of vehicle 110.

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

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

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

[0079] Next, the timing from when vehicle 110 issues an IQN request or a QoS prediction request until it receives QoS Sustainability will be explained using Figure 12, a timing diagram comparing the operation of the comparative example shown in Figures 2 and 3 with the operation of Embodiment 1. Figure 12 shows the timing in the comparative example and the timing in Embodiment 1 together.

[0080] In the comparative example, vehicle 900 sends an IQN request at time Tv, and receives QoS Sustainability after time Td1 following the sequence shown in Figure 2 or Figure 3. Furthermore, the QoS prediction period 170 requested by vehicle 900 is defined as the 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 defined for the V2X service.

[0081] In the above comparative example, since QoS Sustainability cannot be received earlier than time Td1, time Tf1 must be a value greater than time Td1. Therefore, it is not possible to request QoS prediction earlier than time Td1. Furthermore, if the difference between time Tf1 and time Td1 is small, the time leeway Tad1 (=Tf1 - Td1) for vehicle 900 to execute the V2X application becomes small, creating a risk that the V2X application may not be able to be executed properly.

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

[0083] Furthermore, Td1# is defined as the delay time from when the roadside device 130 sends an IQN request until it receives the QoS Sustainability corresponding to that IQN request. Furthermore, vehicle 110 shall receive QoS Sustainability at time Td2 after sending a QoS prediction request at time Tv.

[0084] The QoS prediction period 171 in the IQN request of the roadside device 130 is defined as the time interval T+Tint after time Tf1+Td1# has elapsed from the time the IQN request was issued.

[0085] While the QoS prediction period 171 results in a maximum advance in Tint compared to the QoS prediction period 170, setting Tint to a small value relative to the allowable prediction error τ allows for QoS prediction within the allowable error of the prediction period. Typically, a certain degree of error is acceptable in the QoS prediction period, and it is often preferable for safety reasons to set a larger time interval. Therefore, the time interval for a QoS prediction period of 171 is set to T + Tint.

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

[0087] As shown in Figure 12, in the operation of Embodiment 1, the roadside device 130 receives the QoS Sustainability corresponding to the IQN request transmitted at time T2 at time T2+Td1#. Therefore, if 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, since vehicle 110 and roadside device 130 communicate directly at a nearby location, the time when vehicle 110 receives the QoS Sustainability is also assumed to be the same as time Tv+Td2.

[0088] In Embodiment 1, the sequence from when the vehicle 110 sends a QoS prediction request to when it receives QoS Sustainability includes only two steps, as shown in Figure 11. Therefore, time Td2 is much smaller than time Td1 in the comparative example. Therefore, the time leeway Tad2 from when the vehicle 110 receives QoS Sustainability until the start of the QoS forecast period is larger than the time leeway Tad1 in the comparative example, and sufficient time width can be secured for V2X adaptation operation.

[0089] As described above, since time Td2 is a much smaller value than time Td1, it is possible to set the time Tf until the start of the prediction period to a value smaller than time Tf1, while ensuring the necessary time margin Tad2 for V2X adaptation operation. In Figure 12, the QoS prediction period in this case is shown as QoS prediction period 172.

[0090] Embodiment 2. Figure 13 is a block diagram schematically showing the configuration of the communication system 200 according to Embodiment 2. The communication system 200 comprises a vehicle 210, a roadside device 230, and a server-side system 150.

[0091] In Embodiment 1, vehicle 110 receives V2X services via base station 151, while in Embodiment 2, vehicle 210 receives V2X services via roadside equipment 230. For example, in Embodiment 2, the vehicle 210 performs a 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 V2X services via the roadside device 230 according to the prediction results from the roadside device 230 and the results of the vehicle-side prediction.

[0092] The QoS Sustainability collected by the roadside device 230 represents the communication quality of the communication path from the V2X application server 152 to the roadside device 230. When receiving V2X services via the roadside device 230, the vehicle 210 also needs the predicted communication quality between the roadside device 230 and the vehicle 210, in addition to the QoS Sustainability. This will be explained below.

[0093] Figure 14 is a block diagram schematically showing the main components of the vehicle 210 in Embodiment 2. Note that in Figure 14, the components necessary for vehicle 210 to operate have been omitted.

[0094] 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 Embodiment 2 are the same as the first wireless communication unit 112 and the second wireless communication unit 113 of the vehicle 110 in Embodiment 1.

[0095] V2X Application 211 performs the necessary processing on the vehicle 210 side in order to receive V2X services. For example, V2X Application 211 sends a QoS prediction request and prediction information to the nearest roadside device 230 via the first wireless communication unit 112.

[0096] Then, 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] Furthermore, the V2X Application 211 provides the QoS prediction request and prediction information to the interface QoS prediction unit 215.

[0098] The V2X Application 211 then receives the PC5 QoS prediction result from the interface QoS prediction unit 215, which is the QoS prediction result between the first wireless communication unit 112 and the nearest roadside device 230.

[0099] The V2X Application 211 performs V2X adaptation based on the QoS Sustainability data from the roadside device 230 and the PC5 prediction results from the interface QoS prediction unit 215. However, unlike Embodiment 1, when V2X Application 211 performs V2X adaptation, it receives V2X services via the first wireless communication unit 112 and the roadside equipment 230.

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

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

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

[0103] Furthermore, part or all of the interface monitoring unit 214 and the interface QoS prediction unit 215 can also be composed of processing circuits 12 such as a single circuit, a composite circuit, a program-operated processor, a program-operated parallel processor, an ASIC, or an FPGA, as shown in Figure 5(B). As described above, the interface monitoring unit 214 and the interface QoS prediction unit 215 can be implemented by a processing network.

[0104] Figure 15 is a block diagram showing the schematic configuration of the roadside device 230 of Embodiment 2. The roadside device 230 includes a first wireless communication unit 131, a V2X Application 132, a VAE Client 133, an information gathering 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] In Embodiment 2, the second wireless communication unit 135, QoS Sustainability storage memory 136, read control unit 137, first wireless communication unit 131, V2X Application 132, VAE Client 133, and information collection proxy server 134 of the roadside device 230 are the same as those of the second wireless communication unit 135, QoS Sustainability storage memory 136, read control unit 137, first wireless communication unit 131, V2X Application 132, VAE Client 133, and information collection proxy server 134 of the roadside device 130 in Embodiment 1.

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

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

[0108] Furthermore, some or all of the relay section 238 described above can also be composed of a processing circuit 12 such as a single circuit, a composite circuit, a program-operated processor, a program-operated parallel processor, an ASIC, or an FPGA, as shown in Figure 5(B). As described above, the relay unit 238 can be realized by a processing circuit network.

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

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

[0111] Furthermore, the base station 251 relays the V2X service that the vehicle 210 receives from the V2X application server 152 via the roadside equipment 230.

[0112] As described above, according to Embodiment 2, the vehicle 210 can receive V2X services via the roadside device 230. In this case, the vehicle 210 does not need to be equipped with the second wireless communication unit 113. [Explanation of Symbols]

[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 equipment, 131 First wireless communication unit, 132 V2X Application, 133 VAE Client, 134 Information gathering proxy server, 135 Second wireless communication unit, 136 Memory for storing QoS Sustainability, 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, roadside equipment arranged along the road on which the vehicle travels, and a prediction system that predicts the communication quality of the communication path from a service device that provides V2X services to the vehicle to the roadside equipment, The roadside device sequentially transmits a prediction request requesting the prediction of the communication quality, prediction information which is the information necessary for the prediction, and location information indicating the location of the roadside device to the prediction system at predetermined time intervals. The prediction system, upon receiving the prediction request, uses the prediction information and location information to perform a prediction of the communication quality, and sequentially transmits the prediction result, which is the result of the prediction, to the roadside device. The roadside device sequentially stores the prediction results and, upon receiving a prediction request from the vehicle, transmits the latest stored prediction result to the vehicle. A communication system characterized by the following.

2. The aforementioned forecast information includes a forecast period which is the period defined in the V2X service, The start timing of the prediction period is later than the time that has elapsed between the time the roadside device sends the prediction request and the time it receives the corresponding prediction result. The communication system according to claim 1, characterized by the following:

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

4. The roadside device sequentially measures the delay time and uses the most recent delay time to calculate the start timing of the prediction period. The communication system according to claim 2, characterized by the following:

5. The aforementioned forecast information includes the forecast period, The aforementioned forecast period is the 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 following:

6. The predetermined time interval is shorter than the allowable error for the prediction. A communication system according to any one of claims 1 to 5, characterized by the following:

7. The vehicle performs a vehicle-side prediction, which is a prediction of the communication quality of the 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. A communication system according to any one of claims 1 to 5, characterized by the following:

8. The vehicle performs a vehicle-side prediction, which is a prediction of the communication quality of the 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 claim 6, characterized by the following:

9. Roadside equipment positioned along the road on which vehicles travel, A first communication unit sequentially transmits to a prediction system that predicts the communication quality of the communication path from a service device providing V2X services to the vehicle to the roadside device, a prediction request requesting the prediction of the communication quality, prediction information which is information necessary for the prediction, and location information indicating the location of the roadside device, at predetermined time intervals, and sequentially receives prediction results, which are the results of the prediction, from the prediction system as a response to the prediction request. A storage unit for storing the prediction results, A second communication unit that receives prediction requests from the aforementioned vehicle, The system includes a read control unit that, upon receiving the prediction request from the vehicle, reads the latest stored prediction result and causes the read prediction result to be transmitted to the vehicle by the second communication unit. A roadside device characterized by the following.

10. A program that causes a computer to function as a roadside device positioned along the road on which a vehicle travels, The aforementioned computer, A first communication unit sequentially transmits to a prediction system that predicts the communication quality of the communication path from a service device that provides V2X services to the vehicle to the roadside device, at predetermined time intervals, a prediction request requesting the prediction of the communication quality, prediction information which is information necessary for the prediction, and location information indicating the location of the roadside device, and sequentially receives from the prediction system the prediction result which is the result of the prediction as a response to the prediction request. A storage unit that stores the prediction results, A second communication unit that receives prediction requests from the aforementioned vehicle, and When the prediction request is received from the vehicle, the read control unit will function as a unit that reads the latest stored prediction result and transmits the read prediction result to the second communication unit. A program characterized by the following.

11. A communication method performed by roadside equipment positioned along a road on which a vehicle travels, A prediction system that predicts the communication quality of the communication path from the service device providing V2X service to the vehicle to the roadside device is sequentially transmitted to the prediction system at predetermined time intervals: a prediction request requesting the prediction of the communication quality, prediction information necessary for the prediction, and location information indicating the location of the roadside device. In response to the aforementioned prediction request, the prediction results, which are the results of the prediction, are sequentially received from the prediction system. The aforementioned prediction results are stored, The vehicle receives a prediction request, When the prediction request is received from the vehicle, the latest stored prediction result is read out. The read prediction result is transmitted to the vehicle. A communication method characterized by the following.

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