Wireless devices, communication methods

Abstract

This technology provides a way to reduce the impact on multiple communication systems. [Solution] The first communication unit 112a performs communication using the first band during the first period, and the second communication unit 112b performs communication using the second band during the second period, which is different from the first period. The control unit 116 alternately switches between the first period and the second period. The acquisition unit 114 acquires location information of the wireless device 100. The control unit 116 (1) makes the first period and the second period equal if the location information is outside the first and second areas, (2) makes the first period longer than the second period if the location information is within the second area, and (3) makes the second period longer than the first period if the location information is within the first area.

Description

Technical Field

[0001] The present invention relates to communication technology, and particularly to a wireless device that performs wireless communication and a communication method.

Background Art

[0002] Communication systems such as ETC (Electronic Toll Collection system), DSRC (Dedicated Short Range Communication), and wireless LAN (Local Area Network) have been put into practical use. When the communication bands of both communication corresponding to ETC or DSRC and communication corresponding to wireless LAN are adjacent, the use of wireless LAN will interfere with ETC or DSRC. Therefore, as a technology for reducing the impact on another communication system, technologies for reducing the transmission power of a band or changing a band have been disclosed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There are a plurality of communication bands assigned to wireless LAN, and among them, there are also communication bands that overlap with the communication bands assigned to ETC or DSRC. When one wireless device performs communication corresponding to ETC or DSRC having mutually overlapping communication bands and communication corresponding to wireless LAN, control is required so as not to affect the communication between the two.

[0005] The present invention has been made in view of such a situation, and its object is to provide a technology for reducing the impact on a plurality of communication systems. [Means for solving the problem]

[0006] To solve the above problems, a wireless device according to one aspect of the present invention is a wireless device in a first communication system using a first band and a second communication system using a second band overlapping with the first band, comprising: a communication unit that performs communication using the first band in a first period and performs communication using the second band in a second period different from the first period; a control unit that alternately switches between the first period and the second period in the communication unit; and an acquisition unit that acquires location information of the wireless device. A first area where the use of the second communication system is expected and a second area surrounding the first area are predetermined, and the control unit (1) makes the first period and the second period equal when the location information is outside the first and second areas, (2) makes the first period longer than the second period when the location information is within the second area, and (3) makes the second period longer than the first period when the location information is within the first area.

[0007] Another aspect of the present invention is a communication method. This method is a communication method for wireless devices in a first communication system using a first band and a second communication system using a second band overlapping with the first band, comprising the steps of: performing communication using the first band in a first period and performing communication using the second band in a second period different from the first period; switching between the first period and the second period alternately; and acquiring location information of the wireless device. A first area where the use of the second communication system is expected and a second area surrounding the first area are predetermined, and the switching step is to (1) make the first period and the second period equal if the location information is outside the first and second areas, (2) make the first period longer than the second period if the location information is within the second area, and (3) make the second period longer than the first period if the location information is within the first area.

[0008] Furthermore, any combination of the above components, as well as conversions of the expression of the present invention between methods, apparatus, systems, recording media, computer programs, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0009] According to the present invention, the impact on multiple communication systems can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram showing the configuration of the vehicle according to this embodiment. [Figure 2] This figure shows the spectrum of the signal used in the wireless device shown in Figure 1. [Figure 3] This diagram shows the configuration of the wireless device shown in Figure 1. [Figure 4] This diagram shows an overview of the processing of the wireless device shown in Figure 1. [Figure 5] Figures 5(a)-(c) show the allocation of the first and second periods using the wireless device shown in Figure 1. [Figure 6] Figure 1 is a flowchart showing the communication procedure using the wireless device. [Modes for carrying out the invention]

[0011] Before specifically describing the present invention, the knowledge that formed the basis of the embodiments will be explained. This embodiment relates to a wireless device mounted on a vehicle or the like. The wireless device is capable of communication via wireless LAN and communication via narrow-area communication systems for traffic vehicles such as DSRC and ETC. In wireless LAN, W58 (5770MHz~5850MHz) (hereinafter referred to as the "first band") is defined as a frequency band that is usable outdoors in the United States, Australia, and some parts of Europe, and is recommended for realizing a function such as connecting a smartphone and a navigation system in a vehicle via wireless LAN and projecting (mirroring) the content on the smartphone onto the navigation system. When a wireless device mounted on a vehicle is connected to a terminal device such as a smartphone brought into the vehicle, communication takes place in the first band. In order to stabilize this communication with high throughput, for example, the occupied bandwidth of the wireless LAN is expanded.

[0012] On the other hand, in narrow-range communication systems for traffic vehicles, such as DSRC or ETC, a portion of the 5.8GHz band (5775MHz~5845MHz) (hereinafter referred to as the "second band") is used, as defined by ARIB STD-T55 or T75 and ITU-R M.1453. When wireless LAN is referred to as the "first communication system," narrow-range communication systems for traffic vehicles are referred to as the "second communication system." When wireless devices perform communication via wireless LAN and communication via DSRC / ETC, it is required to reduce the mutual impact between them.

[0013] Figure 1 shows the configuration of vehicle 500. Vehicle 500 includes a wireless device 100 and a terminal device 200, and a roadside unit 400 is provided outside vehicle 500. The wireless device 100 is a communication device for a wireless LAN using the first band. The wireless device 100 is built into an in-vehicle device such as a car navigation system (not shown) installed in vehicle 500. The terminal device 200 is a communication device such as a smartphone brought into the vehicle by the occupants of vehicle 500. The terminal device 200 is compatible with communication systems other than wireless LAN, but here we will focus only on wireless LAN. The terminal device 200 communicates with the wireless device 100 in the first band.

[0014] Furthermore, the wireless device 100 is also a communication device for DSRC / ETC using the second band. The roadside unit 400 is installed outside the vehicle 500 and communicates with the wireless device 100 in the second band. Note that the vehicle 500 is in motion, and communication between the wireless device 100 and the roadside unit 400 occurs when the vehicle 500 approaches the roadside unit 400, and does not occur when the vehicle 500 moves away from the roadside unit 400.

[0015] Figure 2 shows the spectrum of signals used in the wireless device 100. The horizontal axis represents frequency, and the vertical axis represents transmission power. The first signal 50 is a wireless LAN signal transmitted in the first band. The second signal 52 is a DSRC / ETC signal transmitted in the second band. Since the first and second bands overlap, the first signal 50 and the second signal 52 also overlap. Because the bandwidths of the first signal 50 and the second signal 52 overlap, using the first signal 50 and the second signal 52 simultaneously will degrade communication quality due to interference or congestion. The wireless device 100 according to this embodiment performs the following processing to suppress the degradation of communication quality of the first signal 50 and the second signal 52.

[0016] Figure 3 shows the configuration of the wireless device 100. The wireless device 100 includes a first antenna 110a and a second antenna 110b, collectively referred to as antenna 110; a first communication unit 112a and a second communication unit 112b, collectively referred to as communication unit 112; an acquisition unit 114; a control unit 116; and a storage unit 118. The first antenna 110a is configured to transmit and receive a first signal 50 in at least a first bandwidth. The first antenna 110a is, for example, a patch antenna, but is not limited thereto. Known technology may be used for the first antenna 110a.

[0017] The first communication unit 112a is connected to the first antenna 110a and performs communication using the first band during the first period. The first period will be described later. For example, the first communication unit 112a performs wireless LAN communication with the terminal device 200. Therefore, the first communication unit 112a performs modulation / demodulation and encoding / decoding in the wireless LAN. It can also be said that the first communication unit 112a performs processing on the first signal 50.

[0018] The second antenna 110b is configured to be able to transmit and receive a second signal 52 in at least a second band. The second antenna 110b is, for example, a patch antenna, but is not limited thereto. Known techniques may be used for the second antenna 110b. The second communication unit 112b performs communication using the second band in a second period. The second period is a period different from the first period. That is, the first period and the second period are time-divided. For example, the second communication unit 112b performs communication between the roadside unit 400 and the DSRC system. Also, the second communication unit 112b measures the reception level and data error rate of the received second signal 52, and notifies the control unit 116 of the reception state of the second signal 52.

[0019] The acquisition unit 114 corresponds to GNSS (Global Navigation Satellite System), receives signals from GNSS satellites (not shown), and acquires information on the position where the wireless device 100 is located (hereinafter referred to as "position information") based on the received signals. The position information of the wireless device 100 corresponds to the position information of the vehicle 500.

[0020] The control unit 116 alternately switches between the first period 600 and the second period 610 in the communication unit 112 based on the position information received from the acquisition unit 114. Hereinafter, the control in the control unit 116 will be described while using FIGS. 4, FIGS. 5(a)-(c).

[0021] FIG. 4 shows an overview of the processing of the wireless device 100. FIG. 4 shows a road on which the vehicle 500 travels. On the road, a first area 10 and a second area 20 are defined. In FIG. 4, one first area 10 and one second area 20 are shown, but the number of the first areas 10 and the second areas 20 is not limited to "1". The first area 10 is an area where the use of DSRC / ETC is expected, that is, an area near an ETC toll gate or a DSRC communication system. The first area 10 is defined, for example, as a circular area with a radius of 500 m centered on an ETC toll gate. The radius of the first area 10 is not limited to 500 m. The first area 10 is set based on the position information of the toll gate preset in the map information of the navigation system, and the storage unit 118 stores the position information of the first area 10 in advance.

[0022] The second area 20 is an area provided around the first area 10. The second area 20 is defined, for example, as an annular area with an inner diameter of 500 m and an outer diameter of 1 km. The inner diameter is determined to be the same as the radius of the first area 10, and the outer diameter is determined to be a value larger than the inner diameter. The second area 20 is set according to the position information of the first area 10, and the storage unit 118 stores the position information of the second area 20 in advance.

[0023] Also, when the second communication unit 112b executes DSRC / ETC communication using the second band, the control unit 116 receives the position information at that time from the acquisition unit 114. If the position information received from the acquisition unit 114 is not included in the already set first area 10, the control unit 116 newly creates a first area 10 centered on the position information received from the acquisition unit 114. Also, the control unit 116 newly creates a new second area 20 around the newly created first area 10. The control unit 116 updates the position information of the first area 10 and the position information of the second area 20 stored in the storage unit 118 by storing the position information of the newly created first area 10 and the position information of the newly created second area 20 in the storage unit 118.

[0024] Figures 5(a)-(c) show the allocation of the first period 600 and the second period 610 by the wireless device 100. The acquisition unit 114 periodically acquires location information and outputs the location information to the control unit 116. If the received location information is not in the first area 10 or the second area 20 in Figure 4, the control unit 116 makes the first period 600 and the second period 610 equal, as shown in Figure 5(a). In the first period 600, the control unit 116 permits communication from the first communication unit 112a and prohibits communication from the second communication unit 112b. In the second period 610, the control unit 116 prohibits communication from the first communication unit 112a and permits communication from the first communication unit 112a. Here, a no-transmission period 620 is provided between the first period 600 and the second period 610. The non-transmission period 620 is a period during which communication between both the first communication unit 112a and the second communication unit 112b is prohibited. The non-transmission period 620 is provided to suppress interference between the first signal 50 and the second signal 52.

[0025] When vehicle 500 travels along the arrow in Figure 4, vehicle 500 enters the second area 20. If the received location information is within the second area 20, the control unit 116 makes the first period 600 longer than the second period 610, as shown in Figure 5(b). As a result, wireless LAN communication is given priority over DSRC / ETC communication. The control unit 116 may store the first signal 50 received by the priority-executed wireless LAN communication in the storage unit 118.

[0026] As vehicle 500 continues to travel along the arrow in Figure 4, vehicle 500 enters the first area 10 from the second area 20. If the received location information is within the first area 10, the control unit 116 makes the second period 610 longer than the first period 600, as shown in Figure 5(c). As a result, DSRC / ETC communication is given priority over wireless LAN communication. When DSRC / ETC communication is given priority, the wireless device 100 may process the first signal 50 stored in the storage unit 118.

[0027] To ensure that the first signal 50 is not interrupted when vehicle 500 enters the first area 10, it is necessary to store the first signal 50 in advance. For this purpose, in this embodiment, a second area 20 is provided outside the first area 10, and the first signal 50 is received in the second area 20 and stored in the storage unit 118. At that time, the control unit 116 increases the buffer amount of the control unit 116 for storing the first signal 50 received in the first period 600.

[0028] As vehicle 500 continues to move along the arrow in Figure 4, vehicle 500 enters the second area 20 from the first area 10. When the received position information changes from the first area 10 to the second area 20, the control unit 116 makes the first period 600 and the second period 610 equal, as shown in Figure 5(a). This situation corresponds to passing through an ETC toll gate. As vehicle 500 continues to move along the arrow in Figure 4, vehicle 500 exits the second area 20. At this time, the control unit 116 keeps the first period 600 and the second period 610 equal, as shown in Figure 5(a).

[0029] The following describes the amount of data buffer used when the first signal 50 is stored in the storage unit 118 in Figure 5(b). (A) Means 1 Based on the distance (L1) from the ETC gate installation location to the point where the second period 610 is switched to "high" and then returned to normal mode, and the ETC gate passage speed (V1), the predicted passage time for the section where the second period 610 operates in "high" mode is derived in advance as t1 = L1 / V1. The predicted passage time t1 is the buffer amount that needs to be stored in advance for the first signal 50 on the wireless LAN side. V1 is either a fixed speed determined by the legal speed limit, or the time to the point where the second period 610 is switched to "high" is calculated from the current location information and speed, and the speed at the point where the second period 610 is switched to "high" is calculated as a predicted value using the velocity formula for uniformly accelerated motion or the like, using the value from the vehicle's onboard acceleration sensor.

[0030] (B) Means 2 The time to reach the ETC gate is calculated as t2 = L2 / V2, based on the current vehicle speed (V2) and the distance to the ETC gate (L2). During the calculation of this time to reach the gate, the consumption of the first signal 50 is monitored, and the data throughput X (bits / sec) per unit of elapsed time is calculated. From t1 and throughput X calculated in method 1, the amount of data of the first signal 50 that is predicted to be consumed in the "large" section of the second period 610 is calculated as A*X*t1 (A: coefficient).

[0031] This configuration can be implemented in hardware terms using the CPU, memory, and other LSIs of any computer, and in software terms using programs loaded into memory, but here we are depicting the functional blocks that are realized through the cooperation of these components. Therefore, it will be understood by those skilled in the art that these functional blocks can be implemented in various ways using hardware alone, software alone, or a combination of both.

[0032] The operation of the wireless device 100 with the above configuration will now be explained. Figure 6 is a flowchart showing the communication procedure by the wireless device 100. Hereafter, the assignment of the first period 600 and the second period 610 shown in Figure 5(a) will be called the "first pattern", the assignment of the first period 600 and the second period 610 shown in Figure 5(b) will be called the "second pattern", and the assignment of the first period 600 and the second period 610 shown in Figure 5(c) will be called the third pattern. If the location is not within the first area 10 (N in S10) and not within the second area 20 (N in S12), the control unit 116 uses the first pattern (S16). If the location is within the second area 20 (Y in S12) and not a movement from the first area 10 (N in S14), the control unit 116 uses the second pattern (S18). If the location is within the first area 10 (Y in S10), the control unit 116 uses the third pattern (S20). If the movement is within the second area 20 (Y in S12) and is from the first area 10 (Y in S14), the control unit 116 uses the second pattern (S18).

[0033] According to this embodiment, when the location information is outside of the first area 10 and the second area 20, the first period 600 and the second period 610 are made equal, ensuring equal opportunities for communication between wireless LAN and DSRC / ETC. Also, when the location information is within the second area 20, the first period 600 is made longer than the second period 610, allowing wireless LAN to be prioritized over DSRC / ETC. Also, when the location information is within the first area 10, the second period 610 is made longer than the first period 600, allowing DSRC / ETC to be prioritized over wireless LAN. Furthermore, by prioritizing the use of DSRC / ETC in the first area 10, where it is more likely to be used, the impact on multiple communication systems can be reduced. In addition, since the location information of the first area 10 and the second area 20 is stored in advance, map information can be utilized. Furthermore, since the location information for the first area 10 and the second area 20 is updated based on the location information obtained when communication is performed using the second band, the lengths of the first period 600 and the second period 610 can be adjusted even if a new ETC toll gate is installed.

[0034] The present invention has been described above based on examples. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications also fall within the scope of the present invention.

[0035] In this embodiment, the first band is used for wireless LAN and the second band is used for DSRC / ETC. However, this is not limited to this configuration, and for example, the first and second bands may be used for communication systems other than wireless LAN and DSRC / ETC. This modified example expands the scope of application of this embodiment. [Explanation of Symbols]

[0036] 10 First area, 20 Second area, 50 First signal, 52 Second signal, 100 Wireless device, 110 Antenna, 112 Communication unit, 114 Acquisition unit, 116 Control unit, 118 Storage unit, 200 Terminal device, 400 Roadside unit, 500 Vehicle, 600 First period, 610 Second period, 620 Non-transmission period.

Claims

1. A wireless device in a first communication system using a first bandwidth and a second communication system using a second bandwidth that overlaps with the first bandwidth, A communication unit that performs communication using the first bandwidth during the first period and performs communication using the second bandwidth during a second period different from the first period, A control unit that alternately switches between the first period and the second period in the communication unit, The system includes an acquisition unit that acquires location information of the wireless device, A first area where the use of the second communication system is expected, and a second area surrounding the first area are predetermined. The control unit is a wireless device that (1) makes the first period and the second period equal when the location information is outside the first area and the second area, (2) makes the first period longer than the second period when the location information is within the second area, and (3) makes the second period longer than the first period when the location information is within the first area.

2. The system further includes a storage unit that pre-stores location information for the first area and location information for the second area, The wireless device according to claim 1, wherein the control unit controls the length of the first period and the length of the second period based on the location information of the first area and the location information of the second area stored in the storage unit.

3. Equipped with additional memory, The wireless device according to claim 1, wherein the control unit increases the buffer amount of the storage unit for storing signals received during the first period when the position information is within the second area.

4. A method for communication using wireless devices in a first communication system using a first bandwidth and a second communication system using a second bandwidth that overlaps with the first bandwidth, The steps include: performing communication using the first bandwidth during the first period, and performing communication using the second bandwidth during a second period different from the first period; A step of alternately switching between the first period and the second period, The step of acquiring location information of the wireless device is included, A first area where the use of the second communication system is expected, and a second area surrounding the first area are predetermined. A communication method comprising the switching step of (1) making the first period and the second period equal when the location information is outside the first area and the second area, (2) making the first period longer than the second period when the location information is within the second area, and (3) making the second period longer than the first period when the location information is within the first area.

5. A program executed in a wireless device in a first communication system using a first bandwidth and a second communication system using a second bandwidth that overlaps with the first bandwidth, The steps include: performing communication using the first bandwidth during the first period, and performing communication using the second bandwidth during a second period different from the first period; A step of alternately switching between the first period and the second period, The step of acquiring location information of the wireless device is included, A first area where the use of the second communication system is expected, and a second area surrounding the first area are predetermined. The switching step is a program that causes the computer to perform the following actions: (1) make the first period and the second period equal when the location information is outside the first area and the second area; (2) make the first period longer than the second period when the location information is within the second area; and (3) make the second period longer than the first period when the location information is within the first area.

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