Terminal device and communication method of terminal device

Abstract

The present invention relates to a terminal device (100) which is mounted on a mobile body (20) and communicates with a communication device (10) outside the mobile body, wherein the terminal device (100) comprises: an antenna (200) having a plurality of antenna elements arranged along the direction of travel of the mobile body; an area determination unit (104) which obtains propagation environment information of a radio wave propagation path of a signal sent and received between the mobile body and the external communication device, and determines an area defined by the propagation environment information and used for communication using the antenna; an antenna element selection unit (105) which selects at least one of the antenna elements belonging to the area determined by the area determination unit; and a communication unit (106) which uses the antenna element selected by the antenna element selection unit to communicate with the external communication device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on Japanese Patent Application No. 2019-144046 filed on August 5, 2019, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to a terminal device and a communication method of the terminal device. Background Art

[0004] In recent years, services have become available that enable communication between vehicle-mounted terminal devices and base stations, allowing the vehicle to provide information acquired by its sensors to the base station, or for the base station to provide information necessary for the vehicle's operation. Furthermore, research and demonstration experiments are also underway on inter-vehicle communication, which allows one vehicle to exchange information with another.

[0005] Patent Document 1 describes a wireless communication system that achieves directional gain and increased transmission capacity in communications between a base station and a terminal device, even when the terminal device is moving at high speed. Specifically, the system discloses that a precalculated transmission weight vector is stored based on multiple channel information between the base station antenna element and the terminal antenna, which is pre-acquired for each position along the vehicle's travel path. The base station then multiplies the transmission weight vector corresponding to the terminal's position with the data signal to be transmitted to the device, and transmits the resultant data signal.

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-38192.

[0007] Furthermore, the present inventors have discovered the following problems:

[0008] In the wireless communication system of Patent Document 1, the terminal antenna cannot cope with switching of antenna elements. Thus, when the terminal device moves, it is affected by spatial selective fading caused by interference of radio waves. Summary of the Invention

[0009] Therefore, an object of the present invention is to provide a terminal device and a communication method for the terminal device, etc., which can reduce the influence of spatial selective fading.

[0010] A terminal device in one embodiment of the present invention is mounted on a mobile body and communicates with a communication device outside the above-mentioned mobile body, wherein the terminal device has: an antenna, which has multiple antenna elements arranged along the moving direction of the above-mentioned mobile body; an area determination unit, which obtains propagation environment information of the radio wave propagation path of the signal sent and received between the above-mentioned external communication device, and determines the area defined by the above-mentioned propagation environment information and used to communicate using the above-mentioned antenna; an antenna element selection unit, which selects at least one of the above-mentioned antenna elements belonging to the above-mentioned area determined by the above-mentioned area determination unit; and a communication unit, which uses the above-mentioned antenna element selected by the above-mentioned antenna element selection unit to communicate with the above-mentioned external communication device.

[0011] In addition, in another embodiment of the communication method of a terminal device of the present invention, the terminal device is mounted on a mobile body and communicates with a communication device outside the above-mentioned mobile body, wherein the communication method comprises: obtaining propagation environment information of the radio wave propagation path of the signal sent and received between the above-mentioned external communication device, and determining an area defined by the above-mentioned propagation environment information and used for communicating using the above-mentioned antenna; selecting at least one antenna element belonging to the above-mentioned determined area from the above-mentioned multiple antenna elements of an antenna having multiple antenna elements arranged along the moving direction of the above-mentioned mobile body; and using the above-mentioned selected antenna element to communicate with the above-mentioned external communication device.

[0012] In addition, in a communication program of a terminal device in another embodiment of the present invention, the terminal device is mounted on a mobile body and communicates with a communication device outside the above-mentioned mobile body, wherein the communication program executed by the terminal device performs the following steps: obtaining propagation environment information of the radio wave propagation path of the signal sent and received between the terminal device and the above-mentioned external communication device, and determining an upper area defined by the above-mentioned propagation environment information and used for communication using the above-mentioned antenna; selecting at least one antenna element belonging to the above-mentioned determined area from the above-mentioned multiple antenna elements of an antenna having multiple antenna elements configured along the direction of travel of the above-mentioned mobile body; and using the above-mentioned selected antenna element to communicate with the above-mentioned external communication device.

[0013] Effects of the Invention

[0014] According to the terminal device and the communication method of the terminal device, etc. of the present invention, the influence of spatial selective fading can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram for explaining an overview of a communication system 1 including a terminal device according to the first embodiment.

[0016] Figure 2 This is a block diagram illustrating the configuration of the terminal device according to the first embodiment.

[0017] Figure 3 This is a diagram illustrating an antenna included in the terminal device according to the first embodiment.

[0018] Figure 4 This is a diagram for explaining propagation environment information used in the terminal device according to the first embodiment.

[0019] Figure 5 This is a diagram for explaining an area determined by an area determination unit included in a terminal device according to Embodiment 1 and an antenna element selected by an antenna element selection unit.

[0020] Figure 6 This is a flowchart illustrating the operation of the terminal device according to the first embodiment.

[0021] Figure 7 This is a diagram illustrating an antenna included in a terminal device according to Modification 1 of Embodiment 1.

[0022] Figure 8 This is a block diagram illustrating the configuration of a terminal device according to a second modification of the first embodiment.

[0023] Figure 9 This is a diagram illustrating an antenna included in a terminal device according to a second modification of the first embodiment.

[0024] Figure 10 This is a diagram for explaining an area determined by an area determination unit included in a terminal device according to Modification 2 of Embodiment 1, and an antenna element instructed to move by an antenna element movement instruction unit.

[0025] Figure 11 This is a flowchart illustrating the operation of the terminal device according to the second modification of the first embodiment.

[0026] Figure 12 This is a block diagram illustrating the configuration of a terminal device according to the second embodiment.

[0027] Figure 13 This is a diagram illustrating an antenna included in a terminal device according to the second embodiment.

[0028] Figure 14 This is a diagram for explaining antenna elements selected by the antenna element selection unit included in the terminal device according to the first modification of the second embodiment.

[0029] Figure 15 This is a diagram for explaining control of the antenna element selection unit and the communication unit included in the terminal device according to the second modification of the second embodiment.

[0030] Figure 16This is a diagram for explaining an area determined by an area determination unit included in a terminal device according to Embodiment 3 and antenna elements selected by an antenna element selection unit.

[0031] Figure 17 This is a diagram for explaining the area determined by the area determination unit included in the terminal device according to the first modification of the third embodiment, and the antenna elements selected by the antenna element selection unit.

[0032] Figure 18 This is a diagram for explaining an overview of a communication system 2 including a terminal device according to a fourth embodiment.

[0033] Figure 19 This is a block diagram illustrating the configuration of a terminal device according to a fourth embodiment.

[0034] Figure 20 This is a diagram for explaining the area determined by the area determination unit and the antenna elements selected by the antenna element selection unit included in the terminal device according to the fourth embodiment.

[0035] Figure 21 This is a diagram for explaining an overview of a communication system 3 including a terminal device according to the fifth embodiment.

[0036] Figure 22 This is a diagram for explaining an area determined by an area determination unit and antenna elements selected by an antenna element selection unit included in a terminal device according to Embodiment 5. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0038] The present invention described below means the invention described in the claims and is not limited to the following embodiments. In addition, at least the sentences in double quotation marks refer to the sentences described in the claims and are also not limited to the following embodiments.

[0039] The structures and methods described in the dependent claims of the claims are arbitrary structures and methods in the invention described in the independent claims of the claims. The structures and methods of the embodiments corresponding to the structures and methods described in the dependent claims, as well as the structures and methods not described in the claims but only described in the embodiments, are arbitrary structures and methods in the present invention. The structures and methods described in the embodiments when the description in the claims is broader than that in the embodiments also mean illustrative examples of the structures and methods of the present invention and are arbitrary structures and methods in the present invention. In any case, the structures and methods that become necessary for the present invention by being described in the independent claims of the claims.

[0040] The effects described in the embodiments are effects obtained when the configuration of the embodiments is provided as examples of the present invention, and are not necessarily effects obtained by the present invention.

[0041] When there are multiple embodiments, the structures disclosed in each embodiment are not limited to each embodiment and can be combined across embodiments. For example, the structure disclosed in one embodiment can be combined with other embodiments. In addition, the structures disclosed in multiple embodiments can be combined together.

[0042] The findings and problems described in the present invention are not known problems but are independently conceived by the inventors. These facts, together with the structures and methods of the present invention, confirm the inventiveness of the invention.

[0043] The following embodiments are described by taking the case where the present invention is applied to a vehicle among mobile objects as an example. However, unless otherwise specified in the claims, the present invention also includes the case where the present invention is applied to mobile objects other than vehicles.

[0044] (Implementation Method 1)

[0045] 1. Overview of the communication system

[0046] First, use Figure 1 An overview of the communication system according to this embodiment will be described.

[0047] Figure 1 The communication system 1 shown is composed of a base station 10 and a terminal device 100 mounted on a vehicle 20. The terminal device 100 includes an antenna 200 composed of a plurality of antenna elements.

[0048] The base station 10 is, for example, a wireless station fixed on land, and communicates with the terminal device 100 mounted on the vehicle 20. The base station 10 also communicates with a server (not shown). For example, when the terminal device 100 downloads data from the server, the base station 10 relays the data to the terminal device 100. Furthermore, when data transmitted from the terminal device 100, obtained by sensors on the vehicle 20, etc., is uploaded to the server, the base station 10 relays the data to the server.

[0049] Base station 10 can be any name, including a wireless base station, a roadside device, or a communication device, as long as it can relay communications between vehicle 20 and the server. Specifically, when using wide-area wireless communication, base station 10 is a wireless base station installed on a building roof or tower. When using roadside-to-vehicle communication, base station 10 is a roadside device installed on a signal or sign. When using vehicle-to-vehicle communication, base station 10 is installed in the communication device of another vehicle.

[0050] Terminal device 100 is "mounted" on vehicle 20 (equivalent to a "mobile object") and communicates with base station 10 (equivalent to an "external communication device") external to vehicle 20 via communication network 30, sending and receiving necessary information. Vehicle 20 can be a driver-driven vehicle, or an autonomous vehicle, operated by a system according to various levels.

[0051] Here, the term “mounted” includes not only a case where the device is fixed to a moving body or a component of the moving body, but also a case where the device is separated from the moving body and follows the movement of the moving body.

[0052] The terminal device 100 may be any name, such as an information processing device, an information processing module, or a microcomputer, as long as it can transmit and receive the required information and perform calculations or control based on input commands and output results. Alternatively, the terminal device 100 may be a device that assists in driving the vehicle 20 based on data acquired by various sensors. In this case, it is sometimes referred to as an electronic control unit (ECU), a driving assistance device, or an autonomous driving device.

[0053] The communication network 30 used for communication between the base station 10 and the terminal device 100 uses a wireless communication method. Examples of wireless communication methods that can be used include IEEE802.11 (WiFi), IEEE802.16 (WiMAX), W-CDMA (Wideband Code Division Multiple Access), HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution), LTE-A (Long Term Evolution Advanced), 4G, and 5G.

[0054] 2. Structure of Terminal Device 100

[0055] Next, use Figure 2 The configuration of the terminal device 100 according to this embodiment will be described.

[0056] The terminal device 100 includes an antenna 200 , a storage unit 102 , a CPU 103 , a communication unit 106 , and a switch 107 .

[0057] The CPU 103 is connected to the GPS 101 , the storage unit 102 , and the communication unit 106 , controls them, and performs various calculations. In particular, in this embodiment, the CPU 103 implements the area identification unit 104 and the antenna element selection unit 105 .

[0058] In addition, in this embodiment, the GPS 101 is provided outside the terminal device 100 , but may be built into the terminal device 100 .

[0059] The GPS 101 acquires the geographical coordinates, which are the position information of the current position of the vehicle 20. The GPS 101 may be a normal GPS, a differential GPS, or an inertial navigation system (INS).

[0060] Antenna 200 is connected to communication unit 106 via switch 107 and transmits and receives radio waves with base station 10. Antenna 200 is composed of multiple antenna elements with the same performance and function, and each antenna element has the same directivity and gain. Each antenna element can be of any shape, such as linear, planar, or flat, and of any size, as long as it can transmit and receive radio waves used in the above-mentioned wireless communication method. Furthermore, each antenna element is preferably non-directional to enable communication with a mobile object whose direction of movement is not constant, but may also be directional.

[0061] Figure 3 2 is a diagram showing an antenna 200 mounted on a vehicle 20. Figure 3 As shown, the antenna 200 includes a plurality of antenna elements arranged on the upper surface of the vehicle 20 from the front to the rear of the vehicle 20 , that is, along the traveling direction of the vehicle 20 .

[0062] The overall length of the area where antenna 200 is located is preferably longer than the wavelength of the radio waves used for communication. If the length is shorter than the wavelength of the radio waves, the reception strength of the radio waves will be weak in any area where antenna 200 is located due to fading, and there is a possibility that areas with strong reception strength will not be included. The wavelengths of radio waves for the aforementioned wireless communication methods, namely WiFi, WiMAX, W-CDMA, HSPA, LTE, LTE-A, 4G, or 5G, are within the range of 10 cm to 1 m, so the area where antenna 200 is located preferably covers this range.

[0063] The number of antenna elements included in antenna 200 is preferably adjusted so that a plurality of antenna elements are included in one wavelength of radio waves used for communication. For example, the antenna elements are preferably arranged at intervals of a quarter wavelength or less.

[0064] The storage unit 102 stores "propagation environment information" about the radio wave propagation path of signals transmitted and received with the base station 10. In this embodiment, the propagation environment information uses the estimated signal strength attenuation rate, one of the propagation environment evaluation indicators. The signal strength attenuation rate corresponds to the received strength of a reference signal transmitted at a predetermined strength and frequency. Therefore, the signal strength attenuation rate will be referred to as simply the received strength below. The following examples illustrate how the propagation environment information is generated and how the terminal device 100 obtains it.

[0065] (1) When generated by other terminal devices

[0066] The state of the propagation path is estimated based on the measurement results of reference signals received from the base station 10 by other terminal devices mounted on other vehicles, thereby generating propagation environment information using other terminal devices. In this case, the terminal device 100 obtains the propagation environment information by directly receiving it from the other terminal devices using inter-vehicle communication, or by downloading, that is, receiving, information temporarily transmitted from the other terminal devices to the server via the base station 10. In this case, the generated propagation environment information is used to select the antenna element used for reception. In this embodiment, the description is based on the premise of case (1).

[0067] (2) When generated by the terminal device 100 itself

[0068] The state of the propagation path is estimated based on, for example, the measurement results of the reference signal received by the terminal device 100 from the base station 10, thereby generating propagation environment information using the terminal device 100. In this case, the terminal device 100 generates and acquires the propagation environment information based on, for example, the measurement results of the reference signal received by the reference antenna element mounted on the terminal device 100, which will be described later. In this case, the generated propagation environment information is used, similar to (1), to select the antenna element to be used for reception. The case (2) will be described in Embodiment 2.

[0069] (3) When generated by the base station 10

[0070] Propagation environment information is generated by the base station 10, using information such as the measurement results of reference signals transmitted by the terminal device 100 to the base station 10, to estimate the state of the propagation path. In this case, the terminal device 100 acquires the propagation environment information by directly receiving it from the base station 10, or by downloading, i.e., receiving, information temporarily transmitted from the base station 10 to a server. In this case, the generated propagation environment information is used to select the antenna element used for transmission.

[0071] Here, "propagation environment information" refers to the inference result of the state of the propagation path, and as indicators representing the state of the propagation path, for example, in addition to the reception intensity, SNR, SIR, BER, propagation function, propagation path matrix, etc. are listed.

[0072] In addition, "sending and receiving" can refer to either sending or receiving.

[0073] In this embodiment, instead of using a single estimated value of the reception strength as propagation environment information, a radio wave graph is used which represents the correlation between the position information of the receiving device and the estimated value of the reception strength at the position indicated by the position information for each reference signal frequency.

[0074] In this embodiment, a radio wave map is obtained by directly receiving information from another vehicle or from a server (not shown). This radio wave map shows the correlation between position information previously acquired by the other vehicle while driving and the reception strength estimated based on the measurement results of a reference signal received by the other vehicle at the location indicated by the position information. Alternatively, the radio wave map can be generated based on the position information acquired by the own vehicle while driving and the reception strength estimated based on the measurement results of the reference signal received by the own vehicle at the location indicated by the position information. This will be described in Embodiment 2 below.

[0075] The storage unit 102 may be composed of a non-volatile storage device (not shown) such as an HDD or a flash memory, or may be composed of a volatile storage device such as a RAM.

[0076] Figure 4 (A) and (B) show examples of radio wave diagrams containing propagation environment information. Figure 4 (A) is a graph that depicts the reception strength estimated based on the measurement results of the reference signal at each geographic coordinate along the direction of travel of the vehicle for each frequency. The geographic coordinates are location information obtained by GPS101 and therefore represent stationary coordinates. When the direction of travel of the vehicle 20 is set to the left direction in the figure, the more rightward the geographic coordinates are, the more past the location is. The circles in the figure represent the reception strength estimated based on the measurement results of the reference signal. The black circles are positions and frequencies with strong reception strength, the white circles are positions and frequencies with weak reception strength, and the gray circles are in between. The reception strength is represented in three stages in the figure, but continuous values ​​or more than three quantized values ​​can also be used.

[0077] Figure 4 (B) is based on the frequency Figure 4 The numerical value graph is obtained by integrating the reception intensity inferred from the measurement results of the reference signal (A). That is, it is equivalent to the sum or average of the reception intensity in all frequency regions according to each geographical coordinate. Figure 4 The situation of the radio wave diagram (B) is explained.

[0078] Furthermore, as the radio wave map, a reception intensity estimated based on the measurement results of a reference signal in a specific frequency region may be used.

[0079] The area determination unit 104 "obtains" the propagation environment information, that is, the reception strength estimated based on the measurement result of the reference signal, from the storage unit 102, and determines the area "defined" by the reception strength and the area for communication using the antenna 200. In this embodiment, the reception strength obtained from the storage unit 102 is used to determine the area where the reception strength is above a predetermined threshold. For example, Figure 4 In (B), the areas above the specified threshold within the solid line representing the reception strength are identified as area r3, area r2, and area r1, respectively. This identification enables stable communication in areas with a good communication environment. Setting the specified threshold to a value that determines only one area is synonymous with identifying the area with the highest reception strength, so selecting the area with the highest reception strength is also included in this embodiment.

[0080] Here, the term "acquire" includes not only a case where the propagation environment information is acquired from an external communication device or the like, but also a case where the propagation environment information is acquired by the terminal device itself generating the propagation environment information.

[0081] The term "defined" is expressed by the value of the propagation environment information, the position or shape of the propagation environment information, etc. Furthermore, in addition to being directly defined by the propagation environment information, it also includes being indirectly defined by information obtained by transforming, processing, or calculating the propagation environment information.

[0082] The predetermined threshold value may be a fixed value or a variable value obtained by a predetermined calculation.

[0083] The above includes not only the case where the reference value is included but also the case where the reference value is not included.

[0084] As an example of not using a threshold value to determine the area, for example, if the reception strength estimated based on the measurement results of the reference signal is approximately flat, a predetermined area can be determined that is the area immediately ahead of the vehicle 20 in its direction of travel and in which the antenna element can be prepared for reception. By determining this area in this way, communication can be continued for a longer period of time while the vehicle 20 is moving.

[0085] Alternatively, the area can be determined based on the peak position of the reception intensity. For example, if there are multiple peaks, the area with the peak closest to the vehicle 20's direction of travel can be determined. This allows for continued communication while the vehicle 20 is moving.

[0086] Furthermore, the area can also be determined according to the shape of the peak of the reception intensity. For example, in the case of a peak with a steep shape and a peak with a gentle shape, the area where the peak of the latter is located can also be determined. As a method for determining the shape, for example, an evaluation function using the shape is listed. By determining in this way, the antenna element can easily follow the area when the vehicle 20 is traveling. In addition, as the shape of the peak, the area containing the peak with the largest reception intensity can also be determined. As a method for determining the peak with the largest reception intensity, comparing peak values ​​or comparing the integral values ​​of the reception intensity in unit areas are listed.

[0087] Antenna element selector 105 selects an antenna element to be used for communication using communication unit 106. Specifically, it selects at least one antenna element belonging to the area determined by area determination unit 104. Antenna element selector 105 then instructs switch 107 to select the selected antenna element. Switch 107 connects antenna 200 and communication unit 106, switching the antenna elements to connect the antenna element selected by antenna element selector 105 to communication unit 106. Furthermore, in a configuration where multiple antenna elements are each connected to a corresponding independent communication unit 106, antenna element selection can be achieved by setting a weight of 1 in the communication unit 106 corresponding to the selected antenna element, maximizing the signal transmission / reception amplitude, and setting a weight of 0 in the communication unit 106 corresponding to the unselected antenna element, maximizing the signal transmission / reception amplitude. Weights are generally complex numbers that include phase information and are therefore referred to as complex weights. When weights are represented by real numbers, as in the example above, this means that the communication unit does not adjust the phase.

[0088] In this embodiment, the antenna element selector 105 first determines the position of the vehicle 20 on the radio wave map based on the position information of the vehicle 20 obtained by the GPS 101, and then determines the position of each antenna element on the radio wave map. Since the positions of the antenna elements are already known in the terminal device 100, the position of each antenna element can also be determined based on the position information obtained by the GPS 101.

[0089] Then, the antenna element selection unit 105 selects the antenna elements belonging to the area determined by the area determination unit 104. In the case of this embodiment, the antenna elements belonging to the area are selected. Figure 4 Antenna elements in regions r3, r2, and r1 in (B).

[0090] When there are multiple candidate antenna elements, any one antenna element can be selected in the case of SISO.

[0091] More preferably, the area with the highest reception strength is selected. This allows for stable communication using antenna elements located in the most favorable communication environment. In frequency-selective propagation paths, this area varies depending on the frequency. In this case, the element that optimizes frequency selectivity, such as average efficiency across all frequencies, maximum efficiency, or the frequency resources required to achieve the desired communication capacity, is selected.

[0092] Alternatively, more preferably, the antenna element most forward in the direction of travel among the antenna elements belonging to region r3 in the forward direction of travel is selected. Thus, even if an antenna element is temporarily selected, communication can be continued by switching to an adjacent antenna element as vehicle 20 moves. Furthermore, since the same region, i.e., the same stationary coordinate position, is followed, the propagation path state can be considered constant until switching to the next region, reducing the frequency of propagation path estimation processing and the information transmission and reception between the transmitting and receiving nodes required for this processing.

[0093] When two or more antennas are selected, the third and fourth embodiments will be used for explanation.

[0094] The antenna element selection unit 105 periodically selects an antenna element using the position information acquired by the GPS 101 as the vehicle 20 moves. By periodically performing such processing, it is possible to switch to an appropriate antenna element as the vehicle 20 moves.

[0095] When switching antenna elements, instead of using position information, the antenna element selection unit 105 may determine the position of the area specified by the area specification unit 104 on the vehicle 20 based on the "speed information" of the vehicle 20. By using speed information, it is unnecessary to use position information, which takes time to obtain, and thus antenna elements can be switched smoothly even when the vehicle 20 is moving at a high speed.

[0096] Here, "speed information" refers to any information that directly or indirectly indicates the speed of a moving object. For example, in addition to speed, this information also includes acceleration, distance traveled per constant time, and time required to travel a constant distance. It also includes the output of speed pulses, which generate signals such as pulses every time a constant distance is traveled.

[0097] Furthermore, switching of antenna elements means switching to a selected antenna element, and thus switching of antenna elements is a concept encompassed by selection of antenna elements.

[0098] use Figure 5 (A) to (D) illustrate the selection or switching of antenna elements by the antenna element selection unit 105. Figure 5(A) to (D) represent radio wave patterns at times t1 to t4, respectively. Times t1, t2, t3, and t4 pass in sequence. Region r3 is located in front of the vehicle 20 in its travel direction. As vehicle 20 moves, each region shifts rearward, i.e., to the right in the figure, relative to the vehicle 20's direction of travel.

[0099] like Figure 5 As shown in (A), at time t1, the antenna element selection unit 105 selects the antenna element 8 belonging to the region r1. Although the region r1 is the rearmost region in the direction of travel, it is initially selected when the region r1 is the frontmost region in the direction of travel, so that it can be transferred to the region r1 at the current time. Figure 5 Consider the position of (A) as follows.

[0100] like Figure 5 As shown in (B), at time t2, region r1 moves to the rear side in the direction of travel, so the antenna element selector 105 selects antenna element 9 belonging to region r1. In other words, antenna element 8 is switched to adjacent antenna element 9. Switching to an adjacent antenna element is sometimes called replacement.

[0101] like Figure 5 As shown in (C), at time t3, region r1 moves to the rear side in the traveling direction, but since antenna element 9 still belongs to region r1, antenna element 9 continues to be selected. That is, the antenna element is not switched.

[0102] like Figure 5 As shown in (D), at time t4, region r1 further moves to the rear in the direction of travel. In this case, antenna element 10 could also be selected, but since the time for region r1 to move to the rear of vehicle 20 is approaching, antenna element 3, which belongs to region r3 in the forward direction of travel, is selected. In other words, antenna element 3 is switched from antenna element 9.

[0103] In particular, for the antenna elements at the two ends of the antenna element, namely antenna element 1 and antenna element 11, since other antenna elements are present only on one side, the interaction from these other antenna elements differs from the interaction with the central antenna element. In other words, the antenna characteristics differ from those of the other antenna elements. Based on the above, it is preferable that antenna element selection unit 105 does not select the antenna elements located at the frontmost side or the rearmost side of the vehicle 20 in the direction of travel, among the multiple antenna elements.

[0104] exist Figure 5In the example, antenna element selection unit 105 replaces antenna elements in accordance with the area determined by area determination unit 104. However, when viewed from a stationary coordinate system, antenna elements are sequentially switched to antenna elements located at a specific stationary coordinate system as vehicle 20 travels. Specifically, antenna element selection unit 105 selects antenna elements so that the antenna elements performing communication remain "stationary" in the stationary coordinate system. As vehicle 20 moves, antenna elements are sequentially switched from those located in front of vehicle 20 in its direction of travel to those located behind it. This allows for extended use of areas with favorable communication environments, ensuring continued stable communication.

[0105] Here, the term “stationary” means that the antenna elements performing communication are within a constant range of stationary coordinates when viewed from a stationary coordinate system.

[0106] The communication unit 106 communicates with the base station 10 via the communication network 30 using the antenna element selected by the antenna element selection unit 105 .

[0107] 3. Operation of the terminal device 100

[0108] Next, use Figure 6 The operation of the terminal device 100 according to this embodiment will be described.

[0109] also, Figure 6 The flowchart not only shows the communication method using the terminal device 100, but also shows the processing sequence of the program executed by the terminal device 100. In addition, the order of each step can be interchanged as long as there is no relationship in which one step utilizes the result of another step. The same applies to the flowcharts of the following embodiments.

[0110] In step S101 , the GPS 101 acquires position information of the vehicle 20 .

[0111] In step S102, the area identification unit 104 obtains the radio wave map stored in the storage unit 102 and identifies an area defined by the reception intensity estimated based on the measurement results of the reference signal and is an area for communication using the antenna 200. Specifically, in this embodiment, an area is identified where the reception intensity is greater than or equal to a predetermined threshold.

[0112] In step S103 , the antenna element selection unit 105 selects at least one antenna element belonging to the area specified by the area specification unit 104 from among the plurality of antenna elements of the antenna 200 .

[0113] In step S104 , the communication unit 106 communicates with the base station 10 using the selected antenna element.

[0114] In step S105, if the next area needs to be determined, the process returns to step S101 and the process is continued. On the other hand, if the next area needs not to be determined, the process ends.

[0115] 4. Summary

[0116] In summary, according to Embodiment 1, by selecting and using appropriate antennas for communication, the effects of spatially selective fading can be reduced. Furthermore, since the radio wave map is obtained externally, there is no need to generate the map internally. This is particularly effective when the propagation environment information contained in the radio wave map varies little over time, that is, in locations where the propagation environment of the radio wave propagation path varies little.

[0117] (Variation 1 of Implementation Example 1)

[0118] This modification changes the arrangement of the plurality of antenna elements constituting the antenna.

[0119] 1. Configuration of Terminal Device 100

[0120] The terminal device 100 of this modification has an antenna 210 in which a plurality of antenna elements are arranged in a honeycomb shape. Figure 2 Hereinafter, only the structure of the antenna 210 will be described.

[0121] Figure 7 2 is a diagram showing an antenna 210 mounted on a vehicle 20. Figure 7 As shown in FIG. 2A , the plurality of antenna elements constituting the antenna 210 are arranged on the upper surface of the vehicle 20 from the front to the rear of the vehicle 20 , with one side of the honeycomb shape along the direction of travel of the vehicle 20 .

[0122] By adopting such a configuration, even when the vehicle 20 turns to change the route, the antenna element selection unit 105 can select the optimal antenna element. Figure 7 As shown in (B), by using antenna elements along the turning direction, the deviation from the geographical coordinates of the radio wave map can be minimized.

[0123] Furthermore, the antenna element selection unit 105 may select an antenna element group obtained by grouping a plurality of antenna elements instead of a single antenna element. Figure 7 As shown in (C), three antenna elements are configured as one antenna element group. The antenna element group is preferably selected to have a periodic combination relative to the direction of travel. This allows the use of antenna elements that are close to the geographical coordinates of the radio wave chart even if the vehicle 20 is offset in a direction perpendicular to the direction of travel.

[0124] Furthermore, the overall arrangement of the antenna elements may be any arrangement of the antenna elements as long as it can cope with changes in the traveling direction of the vehicle 20. For example, Figure 7 Such a hexagonal shape may be a triangle, a circle, or an ellipse. In addition, the individual antenna elements may be arranged in a lattice shape instead of a honeycomb shape.

[0125] 2. Summary

[0126] As described above, according to the first modification of the first embodiment, in addition to the effects of the first embodiment, an optimal antenna element can be selected even when the vehicle 20 turns, thereby achieving stable communication.

[0127] (Variation 2 of Implementation 1)

[0128] The antenna element of the antenna 200 according to the first embodiment is fixed relative to the vehicle 20 . In contrast, the antenna 220 according to the present modification has a structure in which the antenna element is movable relative to the vehicle 20 .

[0129] 1. Configuration of Terminal Device 100

[0130] Figure 8 This shows the terminal device 100 of this embodiment. Figure 2 In addition to the configuration of the terminal device 100 of the first embodiment shown, it also includes an antenna element driving unit 108 for moving the antenna element. Furthermore, it includes an antenna element movement instruction unit 109 in place of the antenna element selection unit 105. Only the parts having functions different from those of the first embodiment will be described below.

[0131] The antenna element driving unit 108 moves the plurality of antenna elements of the antenna 220 along the traveling direction of the vehicle 20. The antenna element driving unit 108 may be a moving mechanism using magnetism or a moving mechanism using pulleys.

[0132] The antenna element movement instruction unit 109 instructs the antenna element driving unit 108 to move the antenna element so that the antenna element belongs to the area determined by the area determination unit 104. Similar to the antenna element selection unit 105 of the first embodiment, the antenna element movement instruction unit 109 instructs the movement of the antenna element based on the speed information and position information of the vehicle 20.

[0133] Figure 9 This figure shows antenna 220 mounted on vehicle 20. The antenna element of antenna 220 can be moved by antenna element driving unit 108 in a direction opposite to the direction of travel of vehicle 20 so as to follow the area determined by area determination unit 104 as vehicle 20 moves. Furthermore, antenna elements that have moved to the rear end of vehicle 20 can be returned to the front end of vehicle 20 to prepare for the next operation.

[0134] Such a movable antenna element may be a single one, but if multiple antenna elements are provided, there is no need to wait for the antenna element that has moved to the rear end of vehicle 20 to return to the front end of vehicle 20, and the antenna element that is on standby at the front end of vehicle 20 can be used. With this configuration, communication is not interrupted during the return of the antenna element, thereby improving communication stability.

[0135] When multiple antenna elements are provided, based on the principle of moving each antenna element, an antenna element driving unit 108 may be provided for each of the multiple antenna elements, or only one antenna element driving unit 108 may be provided for the multiple antenna elements.

[0136] Figure 10 (A)~(D) and Figure 5 Similarly, (A) to (D) show radio wave diagrams at time t1 to t4, respectively.

[0137] like Figure 10 As shown in FIG. 5(A) , at time t1 , the antenna element movement instruction unit 109 selects the antenna element 1 close to the region r1 .

[0138] like Figure 10 As shown in FIG. 2B , at time t2 , antenna element movement instruction unit 109 instructs antenna element driving unit 108 to move in a direction opposite to the direction of travel of vehicle 20 so that antenna element 1 selected at time t1 belongs to region r1 . Antenna element 1 moves in accordance with the instruction from antenna element movement instruction unit 109 to follow region r1 .

[0139] like Figure 10 As shown in FIG. 2(C), at time t3, the antenna element 1 moves to the rear end side of the vehicle 20.

[0140] like Figure 10 As shown in (D) of FIG. 2 , at time t4, the antenna element movement instruction unit 109 selects the antenna element 2 located at the front end of the vehicle 20. Furthermore, the antenna element movement instruction unit 109 instructs the antenna element driving unit 108 to move the antenna element in a direction opposite to the direction of travel of the vehicle 20 so that the antenna element 2 belongs to a region r3 different from the region r1.

[0141] exist Figure 10In the example, the antenna element movement instruction unit 109 instructs the antenna element to move so that it follows the area determined by the area determination unit 104. However, when viewed from the stationary coordinate system, the antenna element is moved so that it is positioned at a certain stationary coordinate as the vehicle 20 travels. Specifically, the antenna element movement instruction unit 109 instructs the antenna element driving unit 108 to move the antenna element so that it moves in a direction opposite to the direction of travel of the vehicle 20 as the vehicle 20 moves, thereby keeping the communicating antenna element "stationary" in the stationary coordinate system. This allows the use of an area with a good communication environment for a longer period of time, thereby maintaining stable communication.

[0142] 2. Operation of the terminal device 100

[0143] Next, use Figure 11 The operation of the terminal device 100 according to the second modification of the first embodiment will be described.

[0144] The operation of the terminal device 100 of this embodiment is relative to Figure 6 The operation of the terminal device 100 of the first embodiment includes S106 instead of S103. The other steps are the same as Figure 6 Likewise, only Figure 6 A different S106.

[0145] In step S106 , the antenna element movement instructing unit 109 selects an antenna element close to the area specified by the area specifying unit 104 from among the plurality of antenna elements, and instructs the antenna element driving unit 108 to move the antenna element so that the selected antenna element belongs to the area specified by the area specifying unit 104 .

[0146] 3. Summary

[0147] In summary, according to Variation 2 of Implementation 1, the selected antenna element can be moved, allowing communication to continue without replacing the antenna. Furthermore, because the antenna characteristics remain constant at any position within the antenna element's movable range, communication can be performed using the antenna element's entire movable range.

[0148] (Implementation Method 2)

[0149] This embodiment is an embodiment in which a radio wave map including propagation environment information is acquired by the user.

[0150] 1. Configuration of Terminal Device 100

[0151] Figure 12 The terminal device 100 of this embodiment is shown in FIG. Figure 2In addition to the structure of the antenna 200, the antenna 200 also has a propagation environment information collection unit 110. In addition, the antenna 200 has a reference antenna element 230. Figure 2 Common parts, omitted description, quoted Figure 2 Description.

[0152] Figure 13 2 is a diagram showing an antenna 200 mounted on a vehicle 20 and a reference antenna element 230 included in the antenna 200. Figure 13 As shown, antenna 200 includes multiple antenna elements periodically arranged on the upper surface of vehicle 20, from the front to the rear of vehicle 20, that is, along the vehicle's direction of travel. Furthermore, at least one reference antenna element 230 is provided on the front side of vehicle 20 in the direction of travel. A reference antenna element is an antenna element used to receive a reference signal or to transmit and receive a reference signal. The reference antenna element may also function as a conventional antenna element.

[0153] Here, when the antenna element spacing is smaller than a wavelength, the antenna elements at the two ends of the vehicle 20's travel direction are unsuitable as reference antenna elements due to the influence of adjacent elements, which is different from that of other elements. On the other hand, since the reference antenna element is preferably located in the front, the second antenna element from the front is used as reference antenna element 230 in the figure. In other words, an antenna element with the same characteristics as the center antenna element is used as reference antenna element 230. This allows for the acquisition of the radio wave pattern required for antenna element selection by antenna element selector 105 with sufficient time.

[0154] Furthermore, antenna 200 may include two or more reference antenna elements 230. This allows for correction of variations in characteristics between antenna elements. Furthermore, it allows for detection of changes in propagation environment information at the same location. For example, by prioritizing communications in areas where propagation environment information at the same location exhibits less variation, more stable communications can be achieved.

[0155] The propagation environment information collecting unit 110 obtains propagation environment information estimated based on the measurement results of the reference signal received by the reference antenna element 230. The obtained propagation environment information is then stored in the storage unit 102. In this embodiment, the reception strength estimated based on the measurement results when the reference antenna element 230 receives the reference signal transmitted from the base station 10 is obtained and stored in the storage unit 102. In this embodiment, the information is stored as a radio wave graph that shows, for each reference signal frequency, the correlation between position information indicating the location where the reference signal was received and the reception strength estimated based on the measurement results of the reference signal at the location indicated by the position information.

[0156] Region identification unit 104 "acquires" propagation environment information, i.e., reception strength estimated based on the measurement results of the reference signal, from storage unit 102, and identifies a region "defined" by the reception strength and intended for communication using antenna 200. In this embodiment, the reception strength acquired from storage unit 102 is used to identify a region where the reception strength is greater than or equal to a predetermined threshold.

[0157] The antenna element selection unit 105 selects an antenna element based on the position information of the vehicle 20 or the “speed information” of the vehicle 20 acquired by the GPS 101 .

[0158] Here, "speed information" refers to any information that directly or indirectly indicates the speed of a moving object. For example, in addition to speed, this information also includes acceleration, distance traveled per constant time, and time required to travel a constant distance. It also includes the output of speed pulses, which generate signals such as pulses every time a constant distance is traveled.

[0159] Antenna element selection unit 105 selects antenna elements using the same method as in Embodiment 1. Specifically, antenna element selection unit 105 determines the position of vehicle 20 on the radio wave map based on the position information of vehicle 20 acquired by GPS 101, and also determines the position of each antenna element on the radio wave map. Furthermore, antenna element selection unit 105 selects antenna elements belonging to the area specified by area specification unit 104.

[0160] In this embodiment, the position of reference antenna element 230 and the distance between it and the other antenna elements are known, so location information is not necessarily required. Specifically, if the speed information of vehicle 20 is known, it is possible to determine the current position of the area detected by reference antenna element 230 and determined by area determination unit 104, and which antenna element belongs to the determined area. In other words, the position of vehicle 20 on the radio wave map can be determined without using stationary coordinates obtained using GPS 101. Furthermore, since stationary coordinates obtained using GPS 101 are not required, the radio wave map of this embodiment does not necessarily need to be correlated with location information. For example, a correlation between reception time and reception strength is sufficient.

[0161] Furthermore, it is also possible to use the radio wave map of this embodiment and the radio wave map of Embodiment 1. With this configuration, even if the own vehicle cannot obtain the radio wave map due to some circumstances, the radio wave map obtained by another vehicle can be used for supplementary control.

[0162] 2. Summary

[0163] As described above, according to the second embodiment, the radio wave map actually acquired during the travel of the vehicle 20 can be used, and thus the accuracy of the radio wave map can be further increased.

[0164] Furthermore, since position information does not necessarily need to be used, the time required for selecting antenna elements can be shortened, and the power consumption by the GPS 101 can be reduced.

[0165] (Variation 1 of Implementation 2)

[0166] In this embodiment, although propagation environment information is actually collected by the terminal device itself, a predetermined time is required after the reference antenna element 230 receives the reference signal before the antenna element to be used is selected. Specifically, delay time occurs due to the performance of the software and hardware comprising the terminal device 100 until the propagation environment information collection unit 110 calculates the reception strength estimated based on the measurement results of the reference signal received by the reference antenna element 230, the area determination unit 104 determines the area for communication using the antenna 200, and the antenna element selection unit 105 selects an antenna element belonging to that area. On the other hand, delay time occurs due to the software and hardware comprising the communication partner node, as well as the time required for communication to transmit the propagation environment information, until the measurement results based on the propagation environment collection unit are transmitted to the communication partner node and communication reflecting the measurement results is enabled in the communication partner node. In this variation, antenna elements are selected in both the terminal device and the communication partner node device based on the delay time until communication reflecting the propagation environment information becomes possible.

[0167] Figure 14 Indicates the vehicle 20 Figure 13 The reference antenna element 230 also moves along with the movement of the vehicle 20. However, when the delay time is Tr, the reception strength estimated based on the measurement result of the reference signal received by the reference antenna element 230 at time t0 can be used. This is when Tr has passed since t0. Figure 14 In this example, the reception intensity at the stationary coordinate position of reference antenna element 230 at time t0 can be reflected in communications after time t4. Thus, the reception intensity estimated at the position of reference antenna element 230 is sequentially determined at times delayed by delay time Tr as vehicle 20 moves.

[0168] The range of antenna elements, excluding the frontmost and rearmost antenna elements in the direction of travel of vehicle 20, is defined as Ec. Since the frontmost and rearmost antenna elements are adjacent to only one side of the antenna element, their characteristics differ from those of the other antenna elements. In other words, the antenna elements within the Ec range have the same characteristics, so it is preferable to select antenna elements within this range. This applies not only to this embodiment and this variation, but also to all other embodiments.

[0169] If the delay time Tr is not considered, the antenna element selector 105 can select an antenna from the range of Ec(t0) at time t0. However, if the delay time Tr is considered, the vehicle 20, traveling at speed x during the delay time Tr, moves a distance of Tr×x=Dr. In other words, the antenna element located within the range of Dr from the rear end of Ec will be out of the range of Ec(t4) at time t4 after the delay time Tr and cannot be selected. Therefore, at time t4, the antenna element selector 105 selects an antenna element included in Ec'(t0), which is the area determined by the area determination unit 104 and is excluding the range of Dr behind Ec(t0).

[0170] according to Figure 14 For example, at time t4, the antenna element selection unit 105 selects the antenna element n that belongs to the region r2 of the region r1 and the region r2 determined by the region determination unit 104 and is included in Ec′( t0 ).

[0171] As described above, according to this modification, by taking the delay time Tr into consideration, it is possible to switch the antenna elements without interrupting communication.

[0172] In addition, this modification example is applicable to all embodiments other than this embodiment.

[0173] (Variation 2 of Implementation 2)

[0174] In the first embodiment and the present embodiment, it is optional whether or not to consider changes in the propagation environment of the radio wave propagation path within the area specified by the area specifying unit 104. Modification 2 of the present embodiment performs processing based on changes in the radio wave environment within the area.

[0175] Figure 15 and Figure 14 Similarly, the vehicle 20 is mounted Figure 13 The antenna element moves along with the movement of the vehicle 20. Figure 15 In the example, the reception intensity of the region r2 determined by the region determination unit 104 is not constant within the region r2. Figure 15 In FIG, the reception intensity estimated based on the measurement result of the reference signal represents the values ​​of d, c, b, and a in the direction of travel of the vehicle. Hereinafter, the value of the reception intensity that fluctuates is referred to as a fluctuating value.

[0176] At time t0, antenna element selection unit 105 selects antenna element n belonging to region r2 determined by region determination unit 104. Furthermore, at times t0, t1, t2, and t3, the fluctuation values ​​of antenna element n change as d, c, b, and a. Therefore, processing is performed based on these fluctuations in propagation path conditions.

[0177] For example, on the transmitting side, the modulation scheme of the transmitted signal is adaptively changed. For example, when terminal device 100 is the transmitting device, communication unit 106 of terminal device 100 changes the modulation scheme of the signal transmitted by communication unit 106. Alternatively, when base station 10 is the transmitting device, the communication unit of base station 10 changes the modulation scheme of the signal transmitted by base station 10. In this case, terminal device 100 only needs to pre-transmit to base station 10 the estimated result of the propagation path state, that is, in this embodiment, the reception strength estimated based on the measurement result of the reference signal received by reference antenna element 230 of terminal device 100.

[0178] At time t4, as vehicle 20 moves, antenna element n leaves region r2. Therefore, antenna element selector 105 switches the antenna element used for communication from antenna element n to antenna element n+1. Similarly to antenna element n, the predicted fluctuation values ​​for antenna element n+1 at times t4, t5, t6, and t7 are expected to change as d, c, b, and a.

[0179] Therefore, each time the antenna elements are switched, the variation value in the area determined by the area determination unit 104 is repeatedly used.

[0180] Furthermore, processing based on changes in propagation path conditions is not limited to changing the modulation scheme. For example, as part of the transmission processing on the transmitting side, communication unit 106 and the like may adaptively change the coding rate or redundancy of the transmitted signal. Furthermore, communication unit 106 and the like may adaptively change the data rate of information conveyed by the transmitted signal through compression or the like.

[0181] Alternatively, as reception processing on the reception side, when MIMO is used, the communication unit 106 or the like may adaptively change the weight of each antenna element.

[0182] Such processing is effective particularly when the antenna element interval is not sufficiently smaller than the fading pitch.

[0183] As described above, according to this modification, by performing processing based on changes in the propagation environment of the radio wave propagation path, it is possible to prevent loss of transmitted and received data.

[0184] In addition, this modification example is applicable to all embodiments other than this embodiment.

[0185] (Implementation 3)

[0186] This embodiment is an embodiment in which at least one of the transmitting and receiving sides uses multiple antenna elements for communication. Examples of at least one side using multiple antenna elements include SIMO (Single-Input Multiple-Output), MISO (Multiple-Input Single-Output), MIMO (Multiple-Input Multiple-Output), and spatial area index modulation (also known as spatial modulation). In this embodiment, the description is based on the premise of using MIMO.

[0187] 1. Configuration of Terminal Device 100

[0188] The configuration of the terminal device 100 of this embodiment is similar to that of the embodiment except for the functions of the area determination unit 104 and the antenna element selection unit 105. Figure 2 The following is the same as the structure of Figure 2 Common parts, omitted description, quoted Figure 2 Description.

[0189] The region determination unit 104 obtains the received strength of the signal transmitted from the base station 10 and determines a combination of multiple regions that have the best transmission performance, including spatial multiplexing effects. Specifically, for each of the candidate region combinations, a transmission performance index is calculated using a known MIMO algorithm and the results are compared to determine the optimal region combination.

[0190] The antenna element selection unit 105 selects two or more antenna elements belonging to the area determined by the area determination unit 104. Specifically, the antenna element selection unit 105 selects two or more antenna elements for communication with the communication unit 106 using MIMO or the like. Furthermore, the antenna element selection unit 105 replaces the antenna elements so that the vehicle 20 follows the area determined by the area determination unit 104 as the vehicle 20 moves.

[0191] Figure 16 1 is a diagram showing a specific method of selecting a plurality of antenna elements from among the antenna elements mounted on the vehicle 20 .

[0192] As shown in Modification 1 of Embodiment 2, the range of the antenna element used for transmission and reception is set to Ec.

[0193] At time t0, the area determination unit 104 obtains the propagation path inference result until time t0 when the reference antenna element 230 is used. The area determination unit 104 calculates the weights to be multiplied by each transmitting and receiving antenna element for all combinations of the two selected antennas, namely antenna element 1 and antenna element 2, in the antenna range of Ec. The calculation of the weights is performed by an optimization calculation that maximizes the target transmission performance (for example, channel capacity, SINR, difference in received signals between the transmission element selection results when spatial modulation is used, etc.). Then, the combination that maximizes the optimization result is obtained. In Figure 16 The optimization calculation results are displayed using a heat map. The heat map represents the transmission capacity that can be achieved when the weights are optimized. Region determination unit 104 determines region a, which has the highest achievable capacity. Furthermore, information regarding the weights multiplied by the antenna elements of the target node is separately transmitted to the target node. Information regarding the weights multiplied by the antenna elements of the target node may include not only the weights themselves but also the results of selection from a candidate precoding weight matrix, i.e., a codebook, that is, a predetermined set of precoding weight matrix candidates.

[0194] Then, the antenna element selection unit 105 selects the antenna element closest to the center coordinates (p, q) of region a as antenna element 1 and antenna element 2. Region a represents the propagation path estimation result in stationary coordinates, so the antenna element selection unit 105 selects and switches antenna elements as follows to track region a as the vehicle 20 moves.

[0195] At time t1 , the antenna element that belonged to area a at time t0 has not yet left area a, and therefore the antenna element selection unit 105 does not switch between antenna element 1 and antenna element 2 .

[0196] At time t2 , as a result of the vehicle 20 moving forward, the antenna element that belonged to area a at time t1 leaves area a. Therefore, the antenna element selection unit 105 switches antenna element 1 and antenna element 2 to adjacent antenna elements.

[0197] At time t4, antenna element 2 is switched to the rearmost antenna element within the range of Ec. Therefore, at time t5, the region determination unit 104 performs the same calculations as at time t0 based on the propagation path estimation results up to time t4 using reference antenna element 230 to determine a new region a. Furthermore, at time t5, the antenna element selection unit 105 selects the antenna elements closest to the center coordinates of the new region a as antenna elements 1 and 2.

[0198] Furthermore, in the above-described example, the region specifying unit 104 performs the optimization calculation when the rearmost antenna element among the selectable antenna elements is selected. However, the region specifying unit 104 may perform the optimization calculation each time instead.

[0199] In the above example, the antenna element selection unit 105 selects antenna elements within the range of Ec. However, as in Modification 1 of Embodiment 2, the antenna element selection unit 105 may select antenna elements within the range (Ec′) from the rear end of Ec excluding the range of Dr.

[0200] In the above example, multiple antenna elements are selected as receiving antennas, but multiple antenna elements can also be selected as transmitting antennas. In other words, the optimization calculation can be performed on either the transmitting or receiving side. Furthermore, the calculation results can be notified to the device on the other end of the communication.

[0201] In the above example, the region specifying unit 104 calculates the weight to be multiplied by the antenna element, but the antenna element selecting unit 105 may perform this calculation.

[0202] Furthermore, the above example is an example of selecting two antenna elements, but three or more antenna elements may be selected. Alternatively, a set of antenna elements may be used to optimize only the weights, as described in the following modified example.

[0203] 2. Summary

[0204] As described above, according to the third embodiment, in communications using a plurality of antenna elements, the communication quality and the communication speed can be improved, and stable communications can be continued.

[0205] (Variation 1 of Implementation 3)

[0206] In Embodiment 3, a plurality of antenna elements belonging to a region determined by optimization calculation are selected. In this variation, communication is performed by using a set of antenna elements and determining weights to be multiplied by each antenna element.

[0207] Figure 17 This is a diagram showing an example of using a group of antenna elements from among the antenna elements mounted on the vehicle 20 .

[0208] As described in Embodiment 3 and Modification 1 of Embodiment 2, the range of the antenna element used for transmission and reception is set to Ec.

[0209] At time t0 , the region identification unit 104 obtains a propagation path estimation result up to time t0 using the reference antenna element 230 .

[0210] The antenna element selection unit 105 calculates the weights of all antenna elements within the range of Eb and all antenna elements used by the target node in communication with the current terminal based on the propagation path inference result. Eb is the stationary coordinate range of a group of antenna elements, excluding the reference antenna element 230, included in the range of Ec. Eb represents the length of the stationary coordinate system that can be provided by the antenna elements included in the range of Ec during the period of Tm, even if the vehicle 20 moves. When the speed of the vehicle 20 is kept constant, if Tm is shorter, Eb can be lengthened, so that more antenna elements can be used. In addition, if Tm is longer, Eb cannot be lengthened, but the frequency of setting the range of Eb and the frequency of calculating the weights become smaller.

[0211] Furthermore, Tm or Eb may be set to a constant value, or may be made variable according to the speed of the vehicle 20 .

[0212] The weights calculated by the antenna element selector 105 are determined based on the propagation path estimation results to maximize the target transmission performance (e.g., channel capacity, SINR, and differences in received signals between transmit element selection results when spatial modulation is used). Furthermore, the antenna element selector 105 instructs the communication unit 106 to multiply the calculated weights by the signals transmitted and received from each antenna element within the Eb range. The communication unit 106 multiplies the transmitted and received signals by the weights and outputs them to each antenna element.

[0213] At time t1, antenna element selection unit 105 instructs communication unit 106 to multiply the weight calculated at time t0 by the signal transmitted and received from each antenna element within range Eb. At time t1, the antenna elements within range Eb are the same as those at time t0.

[0214] At time t2, the antenna element selector 105 instructs the communication unit 106 to multiply the weights calculated at time t0 by the signals transmitted and received from each antenna element within the range of Eb. At time t2, as the vehicle 20 advances, the antenna elements within the range of Eb differ from those at time t1. Therefore, the antenna element selector 105 switches the antenna element by selecting an antenna element adjacent to the one selected at time t1. The communication unit 106 is instructed to multiply the weights calculated at time t0 for the switched antenna element by the signals transmitted and received from each antenna element within the range of Eb.

[0215] At time t4, the antenna element located at the end of the range of Eb is also located at the end of the range of Ec. Therefore, at time t5, the region determination unit 104 calculates the propagation path estimation result up to time t4 using the reference antenna element 230. Based on the propagation path estimation results, the antenna element selection unit 105 calculates weights for all antenna elements located within the new range of Eb. Furthermore, the antenna element selection unit 105 instructs the communication unit 106 to multiply the calculated weights by the signals transmitted and received by each antenna element located within the new range of Eb.

[0216] In the case of this variant, the area determination unit 104 obtains the propagation path inference result, but microscopically obtains the propagation path inference result in the area obtained by dividing the stationary coordinate range of Eb into equal intervals, so it is synonymous with the situation of obtaining the "area defined by propagation environment information" described in embodiments 1 to 3.

[0217] In this embodiment, the antenna element selection unit 105 calculates weights for each antenna based on the propagation path estimation results and instructs the communication unit to multiply the transmitted and received signals by the calculated weights. However, at a microscopic level, the antenna element utilization is determined by calculating weights corresponding to regions obtained by equally dividing the stationary coordinate range of Eb. This is equivalent to "selecting antenna elements" at a decimal or complex level.

[0218] In the above example, Eb represents the length of the stationary coordinate system that can be provided by the antenna element included in the range of Ec during the period of Tm even if the vehicle 20 moves, but instead, as in the first variant of the second embodiment, Eb can be set to the length of the stationary coordinate system that can be provided by the antenna element of the antenna included in the range (Ec′) from the rear end of Ec excluding the range of Dr during the period of Tm.

[0219] As described above, according to the first modification, a set of antenna elements covering a wide range can be utilized, thereby making communication more stable.

[0220] (Implementation 4)

[0221] This embodiment is an embodiment in which communications using a plurality of different wireless communication methods are performed using a plurality of antenna elements.

[0222] 1. Overview of the communication system

[0223] First, use Figure 18 , an overview of the communication system 2 of this embodiment is described.

[0224] Figure 18The illustrated communication system 2 uses multiple different wireless communication methods. The communication system 2 is composed of a first base station 10a (equivalent to a "first communication device"), a second base station 10b (equivalent to a "second communication device"), and a terminal device 100 mounted on a vehicle 20. The terminal device 100 includes an antenna 200 composed of multiple antenna elements.

[0225] Marked with Figure 1 The same symbol structure is Figure 1 The base stations 10a and 10b each have the same structure as the base station 10. Furthermore, the communication networks 30a and 30b each use any of the wireless communication methods described in the communication network 30. For example, the communication network 30a can be WiFi, and the communication network 30b can be 4G.

[0226] 2. Structure of Terminal Device 100

[0227] Figure 19 The terminal device 100 of this embodiment is shown. In this embodiment, Figure 2 In the configuration of terminal device 100 according to Embodiment 1, two communication units, namely, first communication unit 106a (equivalent to "first communication unit") and second communication unit 106b (equivalent to "second communication unit"), are provided in place of communication unit 106. The following describes only those portions whose functions differ from those of Embodiment 1.

[0228] The storage unit 102 stores propagation environment information of radio wave propagation paths between the first base station 10a and the second base station 10b. In this embodiment, each radio wave map is stored.

[0229] The area identification unit 104 obtains propagation environment information between the first base station 10a and the second base station 10b, and identifies the areas defined by the respective propagation environment information, which are the areas for communication using the antenna 200. In this embodiment, the radio wave map stored in the storage unit 102 is used to identify areas where the signal reception strength under each wireless communication method is greater than a predetermined threshold.

[0230] The antenna element selection unit 105 selects two antenna elements (corresponding to the “first antenna element and the second antenna element”) belonging to each area specified by the area specification unit 104 .

[0231] The first communication unit 106 a communicates with the first base station 10 a using one antenna element, and the second communication unit 106 b communicates with the second base station 10 b using the other antenna element.

[0232] use Figure 20 (A) to (D) illustrate the selection or switching of antenna elements by the antenna element selection unit 105. Figure 20 (A)~(D) use and Figure 5 The same rules apply to (A) to (D). However, the solid line is a radio wave diagram of the radio waves used in the communication network 30a, and the dotted line is a radio wave diagram of the radio waves used in the communication network 30b.

[0233] like Figure 20 As shown in (A) of FIG. 1 , at time t1, the antenna element selection unit 105 selects the antenna element 8 belonging to the area a1. In addition, the antenna element selection unit 105 selects the antenna element 6 belonging to the area b1.

[0234] like Figure 20 As shown in (B) of FIG. 2 , at time t2 , the area a1 and the area b1 move to the rear side in the traveling direction, so the antenna element selection unit 105 selects the antenna element 9 belonging to the area a1 and the antenna element 7 belonging to the area b1 .

[0235] like Figure 20 As shown in (C), at time t3, areas a1 and b1 have moved to the rear in the direction of travel. Antenna element 9 does not yet belong to area a1, so antenna element 9 continues to be selected. In contrast, antenna element 7 is about to leave area b1, so antenna element selector 105 selects antenna element 8, which belongs to area b1.

[0236] like Figure 20 As shown in (D), at time t4, area a1 moves further rearward in the direction of travel. In this case, antenna element 10 could also be selected, but since area a1 is approaching its migration rearward of vehicle 20, antenna element 3, which belongs to area a2 in the forward direction of travel, is selected. In other words, antenna element 3 is switched from antenna element 9. In contrast, antenna element 8 remains selected because it still belongs to area b1.

[0237] 3. Summary

[0238] In summary, according to Embodiment 4, it is possible to utilize a plurality of different wireless communication methods to realize communications in which the influence of spatial selective fading is reduced.

[0239] (Implementation 5)

[0240] Embodiments 1 to 4 are communication systems assuming communication between a base station and a terminal device. In contrast, this embodiment is a communication system assuming so-called inter-vehicle communication.

[0241] 1. Overview of Communication System 3

[0242] First, use Figure 21 The overview of the communication system 3 according to this embodiment will be described.

[0243] Figure 21 The communication system 3 shown assumes so-called inter-vehicle communication. It consists of a terminal device 100 mounted on a vehicle 20 and a terminal device 100a (equivalent to an "other terminal device") mounted on a vehicle 20a (equivalent to an "other mobile object"). The terminal device 100 includes an antenna 200 composed of multiple antenna elements, and the terminal device 100a includes an antenna 200a composed of multiple antenna elements.

[0244] The terminal device 100 is mounted on the vehicle 20 , and communicates with the terminal device 100 a mounted on the vehicle 20 a via the communication network 30 c , thereby transmitting and receiving necessary information.

[0245] 2. Structure of Terminal Device 100

[0246] The configuration of the terminal device 100 of this embodiment is similar to that of the Figure 2 The structure is the same as that of . In addition, the radio wave diagram uses the method described in embodiment 2. Figure 2 The common parts are omitted and quoted. Figure 2 Description.

[0247] The region determination unit 104 obtains the reception strength estimated based on the measurement results of the reference signal transmitted from the terminal device 100a and determines the region with the best transmission performance. In this embodiment, the region with the best inter-terminal communication efficiency is determined based on the combination of the multiple antenna elements of the terminal device 100 and the multiple antenna elements of the terminal device 100a, which form the transmitting and receiving pair. Therefore, in this embodiment, the optimal region is determined for each transmitting terminal and the receiving terminal, and the antenna elements of both terminals are replaced to follow the determined region.

[0248] use Figure 22 The operation of the terminal device 100 according to this embodiment will be described in detail.

[0249] Vehicle 20 has ten antenna elements, 1a through 1j, as antenna 200. Antenna elements 1b, 1c, 1d, and 1e are reference antenna elements. Antenna element 1e is a reference antenna element used for transmitting and receiving reference signals. The remaining antenna elements 1b, 1c, and 1d are reference antenna elements used for receiving reference signals.

[0250] Vehicle 20a has ten antenna elements, 2a through 2j, as antenna 200a. Antenna elements 2b, 2c, 2d, 2e, 2f, 2g, 2h, and 2i are reference antenna elements. Antenna element 2i is a reference antenna element used for transmitting and receiving reference signals. The remaining antenna elements 2b, 2c, 2d, 2e, 2f, 2g, and 2h are reference antenna elements used for receiving reference signals.

[0251] At time t0, terminal device 100 in vehicle 20 transmits a reference signal for wireless frame f1 from antenna element 1e to terminal device 100a in vehicle 20a. Terminal device 100a receives the signal using reference antenna elements 2b through 2i. As a result, terminal device 100a obtains the propagation path measurement results, namely, an estimated reception strength set H(t0, 1e) consisting of eight reference signal reception strengths: p(t0, 1e, 2b) through p(t0, 1e, 2i).

[0252] After completing transmission of wireless frame f1, terminal device 100a in vehicle 20a transmits a reference signal for wireless frame f2 from antenna element 2i, which is then transmitted to terminal device 100 in vehicle 20. Terminal device 100 receives the signal using reference antenna elements 1b through 1e. As a result, terminal device 100 obtains the propagation path measurement results, namely, an estimated reception strength group H(t0, 2i) consisting of four reference signal reception strengths: p(t0, 1b, 2i) through p(t0, 1e, 2i).

[0253] The terminal device 100 and the terminal device 100a share each other's propagation path measurement results by transmitting their respective propagation path measurement results to the counterpart device.

[0254] After time t1, similarly, terminal apparatus 100 and terminal apparatus 100a alternately transmit reference signals, and the counterpart apparatus receives the reference signals to obtain channel measurement results.

[0255] Thus, based on the heat map, which is the propagation path estimation result obtained during a predetermined period, for example, during the period t1 to t7, the area determination unit 104 of the two terminal devices determines the area a, which is the area with high transmission efficiency in the heat map. Furthermore, the antenna element selection unit 105 of the two terminal devices determines the antenna elements belonging to area a. Figure 22 At time t8, terminal device 100 selects antenna element 1g, and terminal device 100a selects antenna element 2h. This heat map is the result of propagation path estimation in stationary coordinates. Therefore, even after vehicles 20 and 20a move, this heat map is used to select antenna elements belonging to area a.

[0256] 3. Summary

[0257] In summary, according to the fifth embodiment, communication can be realized in which the influence of spatial selective fading is reduced in inter-vehicle communication.

[0258] (Inventions from other perspectives)

[0259] Embodiment 1 to Embodiment 5 are embodiments of the following invention described in the claims.

[0260] A terminal device is mounted on a mobile body and communicates with a communication device external to the mobile body, wherein the terminal device comprises:

[0261] an antenna having a plurality of antenna elements arranged along a direction of travel of the mobile object;

[0262] an area determination unit that obtains propagation environment information of a radio wave propagation path for signals transmitted and received with the external communication device and determines an area defined by the propagation environment information and used for communication using the antenna;

[0263] an antenna element selection unit configured to select at least one antenna element belonging to the area determined by the area determination unit; and

[0264] The communication unit communicates with the external communication device using the antenna element selected by the antenna element selection unit.

[0265] However, the first to fifth embodiments are characterized in that the antenna elements used are switched so as to be stationary on the stationary coordinate system, and therefore they can also be understood as embodiments of the following invention.

[0266] A terminal device is mounted on a mobile body and communicates with a communication device external to the mobile body, wherein the terminal device comprises:

[0267] an antenna having a plurality of antenna elements arranged along a direction of travel of the mobile object;

[0268] an antenna element selection unit configured to select the antenna elements so as to sequentially switch from the antenna elements on the front side in the moving direction of the moving object toward the antenna elements on the rear side in the moving direction as the moving object moves, so that at least one of the antenna elements performing communication remains stationary on a stationary coordinate system; and

[0269] The communication unit communicates with the external communication device using the antenna element selected by the antenna element selection unit.

[0270] Here, “stationary” means that the antenna elements performing communication are within a constant range of stationary coordinates when viewed from a stationary coordinate system.

[0271] In particular, in Variation 1 of Embodiment 3, from a macroscopic perspective, the area defined by the range of Eb is not defined by propagation environment information; Eb only needs to be a predetermined length. Furthermore, from a macroscopic perspective, antenna element selector 105 simply selects antenna elements within the range of Eb. Specifically, Eb represents the stationary coordinate range, and a group of antenna elements is selected by sequentially switching between antenna elements within this range.

[0272] In addition to the invention of the terminal device, the same applies to the invention of the communication method and the invention of the communication program having the same characteristics.

[0273] (Summarize)

[0274] The features of the terminal device and the communication method executed by the terminal device in each embodiment of the present invention have been described above.

[0275] The terms used in the embodiments are for illustrative purposes only and may be replaced with synonymous terms or terms having synonymous functions.

[0276] The block diagrams used in the description of the embodiments are diagrams that classify and organize the structure of the terminal device by function. These functional modules are implemented through any combination of hardware or software. In addition, because they are diagrams that represent functions, they can also be understood as disclosures of the invention of the method.

[0277] Functional blocks that can be understood as the processes, procedures, and methods described in each embodiment may be interchanged in order unless there is a constraint such as a relationship in which one step utilizes the results of another step.

[0278] The terms “first” and “second” used in each embodiment and claims are used to distinguish two or more structures or methods of the same kind, and do not limit the order or superiority.

[0279] In addition, the present invention can be implemented not only by dedicated hardware having the structure and functions described in each embodiment, but also as a combination of a program for implementing the present invention recorded on a recording medium such as a memory or a hard disk, and general hardware having a dedicated or general-purpose CPU and memory capable of executing the program.

[0280] Programs stored in a non-migrating physical recording medium of dedicated or general-purpose hardware (for example, an external storage device (hard disk, USB memory, CD / BD, etc.), or an internal storage device (RAM, ROM, etc.)) can also be provided to the dedicated or general-purpose hardware via the recording medium, or from a server via a communication line without using a recording medium. In this way, the latest functions can always be provided through program upgrades. The recording medium and internal storage device of dedicated or general-purpose hardware are examples of computer-readable non-migrating physical storage media.

[0281] Industrial applicability

[0282] The movable body of the present invention has been described by taking a vehicle as an example, but it may be a two-wheeled motorcycle, a bicycle with an electric motor, a railway vehicle, and of course a ship, an aircraft, etc.

Claims

1. A terminal device mounted on a mobile body and communicating with a communication device external to the mobile body, wherein: The terminal device has: an antenna having a plurality of antenna elements arranged along a direction of travel of the mobile object; an area specifying unit that obtains propagation environment information of a radio wave propagation path for signals transmitted and received with the external communication device, and specifies an area defined by the propagation environment information and used for communication using the antenna; an antenna element selection unit that selects at least one of the antenna elements belonging to the area determined by the area determination unit; as well as a communication unit that communicates with the external communication device using the antenna element selected by the antenna element selection unit, The antenna element selection unit does not always select the antenna element at the frontmost side in the direction of travel of the moving object and the antenna element at the rearmost side in the direction of travel of the moving object among the plurality of antenna elements.

2. The terminal device according to claim 1, wherein The antenna element selection unit selects the antenna elements so as to sequentially switch from the antenna elements on the front side in the moving direction of the moving object to the antenna elements on the rear side in the moving direction as the moving object moves, so that the antenna elements performing communication remain stationary on the stationary coordinates.

3. The terminal device according to claim 1, wherein The antenna element selection unit selects the antenna element belonging to a range other than a range corresponding to a distance moved by the moving object within a predetermined delay time, within the area determined by the area determination unit. The terminal device according to claim 1 , wherein: The communication unit adaptively changes a transmission process or a reception process based on a change in the propagation environment information in the area determined by the area determination unit. The terminal device according to claim 1 , wherein: The antenna element selection unit selects the antenna element by instructing the communication unit to multiply a signal to be transmitted and received by a predetermined weight. The terminal device according to claim 1 , wherein: The plurality of antenna elements of the antenna are arranged in a honeycomb shape.

7. The terminal device according to claim 1, wherein: The terminal device further includes a storage unit for storing the propagation environment information. The terminal device according to claim 1 , wherein: The terminal device obtains the propagation environment information generated in advance by another mobile object or the base station device from the other mobile object or the base station device, The antenna element selection unit selects the antenna element based on position information or speed information of the moving object.

9. The terminal device according to claim 1, wherein: The antenna has at least one reference antenna element on the front side of the moving object in the direction of travel. The terminal device obtains the propagation environment information generated based on the signal received by the reference antenna element, The antenna element selection unit selects the antenna element based on position information or speed information of the moving object.

10. The terminal device according to claim 1, wherein The antenna element selection unit selects two or more antenna elements used for MIMO (Multiple-Input and Multiple-Output). The terminal device according to claim 1 , wherein: The external communication device includes a first communication device and a second communication device, The communication unit includes a first communication unit and a second communication unit, The area determination unit obtains propagation environment information of radio wave propagation paths of respective signals transmitted and received between the first communication device and the second communication device, and determines the respective areas defined by the respective propagation environment information and used for communication using the antenna. The antenna element selection unit selects the first antenna element and the second antenna element belonging to each of the areas determined by the area determination unit. The first communication unit communicates with the first communication device using the first antenna element, and the second communication unit communicates with the second communication device using the second antenna element.

12. The terminal device according to claim 1, wherein The external communication device is a base station device.

13. The terminal device according to claim 1, wherein The external communication device is another terminal device mounted on another mobile body.

14. A communication method for a terminal device, the terminal device being mounted on a mobile body and communicating with a communication device external to the mobile body, wherein: The communication method has the following steps: Acquiring propagation environment information of a radio wave propagation path for signals transmitted and received with the external communication device, and determining an area defined by the propagation environment information and used for communication using an antenna; selecting at least one antenna element belonging to the determined area from among a plurality of antenna elements of an antenna having a plurality of antenna elements arranged along a traveling direction of the mobile object; as well as using the selected antenna element to communicate with the external communication device, The step of selecting the at least one antenna element includes always not selecting the antenna element at the frontmost side in the direction of travel of the moving object and the antenna element at the rearmost side in the direction of travel of the moving object among the plurality of antenna elements.

15. A recording medium recording a communication program executed by a terminal device mounted on a mobile body and communicating with a communication device external to the mobile body, wherein: The following steps are performed by executing the communication program: Acquiring propagation environment information of a radio wave propagation path for signals transmitted and received with the external communication device, and determining an area defined by the propagation environment information and used for communication using an antenna; selecting at least one antenna element belonging to the determined area from among a plurality of antenna elements of an antenna having a plurality of antenna elements arranged along a traveling direction of the mobile object; as well as using the selected antenna element to communicate with the external communication device, The step of selecting the at least one antenna element includes always not selecting the antenna element at the frontmost side in the direction of travel of the moving object and the antenna element at the rearmost side in the direction of travel of the moving object among the plurality of antenna elements.

16. A terminal device mounted on a mobile body and communicating with a communication device external to the mobile body, wherein: The terminal device has: an antenna configured with an antenna element movable along a direction of travel of the moving object; an antenna element driving unit that moves the antenna element along a traveling direction of the moving object; an area determination unit that obtains propagation environment information of a radio wave propagation path for signals transmitted and received with the external communication device, and determines an area defined by the propagation environment information, the area being the area for communication using the antenna; an antenna element movement instruction unit configured to instruct the antenna element driving unit to move the antenna element so that the antenna element belongs to the area determined by the area determination unit; as well as a communication unit that communicates with the external communication device using the antenna element, The antenna elements that communicate with the external communication device always exclude the antenna elements at the frontmost side in the direction of travel of the moving object and the antenna elements at the rearmost side in the direction of travel of the moving object.

17. The terminal device according to claim 16, wherein: The antenna element movement instruction unit instructs the antenna element driving unit to move the antenna element so that the antenna element moves in a direction opposite to a moving direction of the moving object as the moving object moves, so that the communicating antenna element remains stationary on a stationary coordinate.

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