Wireless communication device, wireless communication system, wireless communication method, and program

Abstract

A wireless communication device comprising: a communication control unit that indicates data transmission to a counterpart device when a condition is satisfied that the transmission distance to the counterpart device being connected by wireless communication is within a predetermined range; and one or more wireless communication units that wirelessly perform data transmission to the counterpart device in response to the indication of the communication control unit.　

Description

Wireless communication device, wireless communication system, wireless communication method, and program

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

[0002] In wireless communication using a high-frequency band such as millimeter waves or quasi-millimeter waves, it is possible to secure a wider bandwidth compared to wireless communication using the microwave band. Examples of wireless communication methods using a high-frequency band include 3GPP (3rd Generation Partnership Project) (3GPP is a registered trademark), 5G NR (5th Generation New Radio), and IEEE802.11ad. Wireless communication using a high-frequency band has advantages such as high directivity of wireless signals in the propagation path and less interference with other wireless communications. Therefore, studies are underway to promote the spread of wireless communication using a high-frequency band (see, for example, Non-Patent Document 1).

[0003] The distance attenuation amount of wireless signals in the propagation path increases according to the frequency of the wireless signals. Wireless signals in wireless communication such as IEEE802.11ad using the 60GHz band are easily absorbed by oxygen in the propagation path. For these reasons, in wireless communication using a high-frequency band such as the millimeter wave band, it is common for a wireless communication device to form a directional beam (beamforming) toward a wireless communication device that is the communication partner and transmit a signal. It is also common for a wireless communication device to form a directional beam and receive a signal.

[0004] FIG. 4 is a conceptual diagram of a wireless communication system S using beamforming in a general millimeter wave band. The wireless communication device 1 can form directional beams in different directions. In FIG. 4, as an example, an example in which the wireless communication device 1 forms directional beams B1 to B9 in 9 directions with different angles is shown. The wireless communication device 1 selects a beam that maximizes the received power at the opposing wireless communication device 2 from the directional beams B1 to B9. In IEEE802.11ad, for example, beam selection is performed by a procedure called SLS (Sector Level Sweep) (see, for example, Non-Patent Document 2).

[0005] First, the wireless communication device 1, which initiates the communication, sequentially transmits signals using the available beams (directional beams B1 to B9) in a time-division multiplexing manner. In the following explanation, this sequential transmission of signals using the available beams is called a beam sweep. Wireless communication device 2 receives each signal transmitted from wireless communication device 1 using the beam with the maximum beam width and measures the received power of each received signal. Wireless communication device 2 may also sequentially transmit signals using beams in the same manner. Regarding beam selection by wireless communication device 1, beam selection is completed when wireless communication device 2 shares the ID of the beam that obtained the maximum received power with wireless communication device 1. For example, beam selection is completed in wireless communication device 1 when wireless communication device 2 feeds back the ID of the beam that obtained the maximum received power to wireless communication device 1.

[0006] Similarly, in 5G NR, multiple signal blocks called SS / PBCH (Synchronization Signal / Physical Broadcast Channel) are transmitted sequentially in time-division for each beam of the wireless communication device 1. The wireless communication device 2 reads the signal blocks transmitted sequentially in time-division for each beam and feeds back the information of the beam with the highest received power to the wireless communication device 1, thereby completing the initial beam selection.

[0007] In the high-frequency band, in addition to the magnitude of distance attenuation, if an obstruction is present in the propagation path between the antennas of the transmitting and receiving wireless communication devices, the propagation loss increases rapidly, making signal transmission difficult. For this reason, in general, high-frequency band communication is assumed to be conducted in a line-of-sight environment where there are no obstructions between the antennas of the transmitting and receiving wireless communication devices. In such a case, the direction of the beam used by wireless communication device 1 directly indicates the direction of wireless communication device 2. In addition, if a wireless communication device is equipped with a distance estimation function using the round-trip time (RTT) of the signal, as shown in Non-Patent Document 3, for example, it becomes possible to estimate the relative position of one wireless station device from another wireless station device using the transmitted signal itself.

[0008] Furthermore, especially when using high-frequency bands, there is more headroom in the frequency resources compared to low-frequency bands. In other words, wireless communication devices using high-frequency bands are often allocated relatively wide bandwidths. Since signal bandwidth and symbol rate are proportional, the symbol rate increases when using wideband signals. That is, the symbol interval in the time domain becomes shorter, which is expected to improve the accuracy of measuring the round-trip time of communication signals. Therefore, it becomes possible to easily estimate the communication distance without combining and processing signals transmitted from multiple distributed transmitters, as in conventional GPS (Global Positioning System).

[0009] International Publication No. 2022 / 024241

[0010] Takiha, et al., "Standardization Trends and Elemental Technologies of Millimeter-Wave Wireless LAN Systems," IEICE Communications Society Magazine, Autumn 2016, No. 38, pp. 100-106. IEEE, "Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 3: Enhancements for Very High Throughput in the 60 GHz Band," IEEE Standard for Information Technology - Telecommunications and information exchange between systems, Local and metropolitan area networks - Specific requirements, December 28, 2012. Iwakuni, Tatsuhiko, Uchida, Taisei, Huang, Junxiang, Wai, Hideki, Kita, Naoki, "Experimental Evaluation of Handover Control Using Range Measurement Function in High-Frequency Band Wireless Communication Systems," B-5-56, IEICE Communications Society Convention 2020.

[0011] In wireless communication systems using high-frequency bands, the communication area is narrower compared to wireless communication systems using lower frequency bands due to the effect of distance attenuation, which increases proportionally to the frequency. Therefore, as shown in Figure 5, for example, a portable wireless communication device 2, such as a terminal device, is more likely to leave the communication area A of wireless communication device 1 during data transmission as it moves. In this case, not only is data transmission in wireless communication device 2 interrupted, but wireless communication device 2 may also retransmit unnecessary data because it perceives a temporary deterioration in transmission quality.

[0012] As a result, in the vicinity of wireless communication device 2 (including, for example, outside of communication area A), data retransmitted by wireless communication device 2 can cause interference between wireless communication devices transmitting on the same frequency band, potentially degrading transmission characteristics. This leads to a problem of reduced wireless transmission efficiency. This problem is not limited to portable wireless communication devices such as terminal devices, but also occurs in wireless communication devices such as base stations that communicate with mobile terminal devices.

[0013] In view of the above circumstances, the present invention aims to provide a technology that can suppress the decrease in wireless transmission efficiency.

[0014] One aspect of the present invention is a wireless communication device comprising: a communication control unit that instructs data transmission to a counterpart device when the condition is met that the transmission distance between the counterpart device and the communication control unit during wireless communication is within a predetermined range; and one or more wireless communication units that wirelessly transmit the data to the counterpart device in response to the instruction of the communication control unit.

[0015] One aspect of the present invention is a wireless communication system comprising a first communication device and a second communication device that performs wireless communication with the first communication device, wherein the first communication device acquires information indicating the transmission distance between itself and the second communication device during wireless communication, and transmits the acquired information indicating the transmission distance to the second communication device, and the second communication device comprises a communication control unit that, based on the information indicating the transmission distance transmitted from the first communication device, instructs the first communication device to transmit data when the condition that the transmission distance is within a predetermined range is met, and one or more wireless communication units that perform the data transmission to the first communication device wirelessly in response to the instruction of the communication control unit.

[0016] One aspect of the present invention is a wireless communication method that, when the condition is met that the transmission distance between the connected wireless communication device and the opposing device is within a predetermined range, instructs the opposing device to transmit data, and transmits the data wirelessly to the opposing device in response to the instruction.

[0017] One aspect of the present invention is a program that causes a computer to execute a communication control step of instructing data transmission to a peer device when the condition is met that the transmission distance between the computer and the peer device during wireless communication is within a predetermined range, and a wireless communication step of performing the data transmission to the peer device wirelessly in response to the instruction in the communication control step.

[0018] This invention makes it possible to suppress the decrease in wireless transmission efficiency.

[0019] This figure shows an example configuration of a wireless communication device in the first embodiment. This flowchart shows the processing flow of a wireless communication device in the second embodiment. This figure shows an example configuration of a wireless communication device in the second embodiment. This is a conceptual diagram of a wireless communication system S that uses beamforming in the general millimeter-wave band. This is a diagram to explain the problem.

[0020] One embodiment of the present invention will be described below with reference to the drawings.

[0021] (First Embodiment) Figure 1 shows an example of the configuration of the wireless communication device 10 in the first embodiment. The wireless communication device 10 performs wireless communication with other wireless communication devices. Here, as an example, the wireless communication device 10 is described as a terminal device and the other wireless communication devices are base station devices. The wireless communication device 10 and the other wireless communication devices are provided in a wireless communication system (for example, the wireless communication system S shown in Figure 4). The other wireless communication devices are provided with one or more wireless communication units and perform wireless communication with the wireless communication device 10. The number of wireless communication devices 10 and other wireless communication devices provided in the wireless communication system (for example, the wireless communication system S shown in Figure 4) is not particularly limited.

[0022] Note that the wireless communication device 10 may be a base station device, and the other wireless communication devices may be terminal devices. When the wireless communication device 10 is a base station device, the configuration of the base station device will be the same as that of the wireless communication device 10. The wireless communication device 10 is one embodiment of the first wireless communication device, and the other wireless communication devices are one embodiment of the second wireless communication device.

[0023] (Configuration of the wireless communication device 10) The wireless communication device 10 comprises a data storage unit 11, a data processing unit 12, a wireless communication unit 13, a round-trip time measurement signal transmission unit 14, a round-trip time measurement unit 15, a communication control unit 16, and an antenna 17.

[0024] The data storage unit 11 stores the data to be transmitted. The data storage unit 11 is, for example, a buffer.

[0025] The data processing unit 12 reads the data stored in the data storage unit 11 in response to a data transmission instruction from the communication control unit 16, and outputs the read data to the wireless communication unit 13. A data transmission instruction is an instruction to transmit the data stored in the data storage unit 11. For example, in response to a data transmission instruction from the communication control unit 16, the data processing unit 12 reads the data stored in the data storage unit 11 in the order in which it was stored. Then, the data processing unit 12 outputs the data to the wireless communication unit 13 in the order in which it was read.

[0026] The data processing unit 12 terminates reading data stored in the data storage unit 11 in response to a data stop instruction from the communication control unit 16. The data stop instruction is an instruction to stop reading data stored in the data storage unit 11. The data processing unit 12 may temporarily hold the data being read at the time the data stop instruction is received, instead of outputting it to the wireless communication unit 13.

[0027] The wireless communication unit 13 communicates with other wireless communication devices. The wireless communication unit 13 communicates with other wireless communication devices using, for example, a wireless communication method using a high frequency band (e.g., 3GPP, 5G NR, or IEEE 802.11ad). The wireless communication unit 13 transmits, for example, a round-trip time measurement signal output from the round-trip time measurement signal transmission unit 14 to the other wireless communication device via the antenna 17. The round-trip time measurement signal is a signal used to estimate the transmission distance between the wireless communication device 10 and the other wireless communication device that is connected. When the wireless communication unit 13 receives a response to the round-trip time measurement signal from the other wireless communication device that is connected, it outputs the received response to the round-trip time measurement signal to the round-trip time measurement unit 15.

[0028] Furthermore, the wireless communication unit 13 causes the data output from the data processing unit 12 to be transmitted to other connected wireless communication devices via the antenna 17.

[0029] The wireless communication unit 13 may control the amplitude or phase of the antenna 17 to form directional beams in different directions according to instructions from the communication control unit 16. In this configuration, the number of directional beams formed by the wireless communication device 10 is not particularly limited. A directional beam is a beam that has directionality in a specific direction. The wireless communication unit 13 transmits signals by switching directional beams according to instructions from the communication control unit 16. The wireless communication unit 13 receives signals (e.g., responses) transmitted from other wireless communication devices via the antenna 17.

[0030] The round-trip time measurement signal transmission unit 14 generates a round-trip time measurement signal in response to a measurement signal transmission instruction from the communication control unit 16, and outputs the generated round-trip time measurement signal to the wireless communication unit 13. The measurement signal transmission instruction is an instruction to start the generation of the round-trip time measurement signal. The round-trip time measurement signal transmission unit 14 instructs the round-trip time measurement unit 15 to measure the round-trip time at the timing when the round-trip time measurement signal is output.

[0031] The round-trip time measurement unit 15 measures the round-trip time from the time of transmission of the round-trip time measurement signal to the time of reception of the response to the round-trip time measurement signal, in response to instructions from the round-trip time measurement signal transmission unit 14. For example, the round-trip time measurement unit 15 acquires the timing at which it is instructed by the round-trip time measurement signal transmission unit 14 to measure the round-trip time as the transmission time of the round-trip time measurement signal. The round-trip time measurement unit 15 acquires the timing at which it receives a response to the round-trip time measurement signal via the wireless communication unit 13 as the reception time of the response to the round-trip time measurement signal. The round-trip time measurement unit 15 measures the round-trip time based on the transmission time and the reception time. For example, the round-trip time measurement unit 15 measures the difference between the transmission time and the reception time as the round-trip time.

[0032] The transmission time of the round-trip time measurement signal and the reception time of the response to the round-trip time measurement signal are not limited to those described above. The transmission time of the round-trip time measurement signal may be, for example, the time when the round-trip time measurement signal is transmitted by the wireless communication unit 13. The reception time of the response to the round-trip time measurement signal may be, for example, the time when the response to the round-trip time measurement signal is received by the wireless communication unit 13. In this case, the wireless communication unit 13 outputs information indicating the transmission time and information indicating the reception time to the round-trip time measurement unit 15. The round-trip time measurement unit 15 measures the round-trip time based on the information indicating the transmission time and information indicating the reception time output from the wireless communication unit 13.

[0033] The communication control unit 16 controls the operation of the data processing unit 12, the wireless communication unit 13, and the round-trip time measurement signal transmission unit 14. For example, if the wireless communication unit 13 is connected to another wireless communication device, the communication control unit 16 sends a measurement signal transmission instruction to the round-trip time measurement signal transmission unit 14 to transmit a round-trip time measurement signal. Furthermore, the communication control unit 16 estimates the transmission distance between itself and the other connected wireless communication device based on the round-trip time (RTT) measured by the round-trip time measurement unit 15. For example, the communication control unit 16 estimates the transmission distance using the round-trip time and the speed of light. In this way, the communication control unit 16 obtains distance information indicating the transmission distance. The communication control unit 16 determines whether the data transmission conditions have been met based on the estimated transmission distance.

[0034] The data transmission condition is the condition for transmitting data stored in the data storage unit 11, for example, that the transmission distance between the wireless communication device 10 and other connected wireless communication devices is within a predetermined range. The predetermined range is the range in which communication can be performed using the wireless communication method of the wireless communication unit 13. In other words, when the data transmission condition is met, it means that the wireless communication device 10 is located within the range in which communication can be performed using the wireless communication method of the wireless communication unit 13 with other connected wireless communication devices. In this way, the wireless communication device 10 avoids interruptions in data transmission and data retransmission by appropriately detecting whether or not it is within the range in which communication can be performed using the wireless communication method of the wireless communication unit 13 based on the transmission distance.

[0035] When the data transmission conditions are met, the communication control unit 16 checks whether there is data to be transmitted in the data storage unit 11. If there is data to be transmitted in the data storage unit 11, the communication control unit 16 instructs the data processing unit 12 to transmit the data to other connected wireless communication devices.

[0036] On the other hand, the communication control unit 16 will not transmit data if the data transmission conditions are not met. For example, if the data transmission conditions are no longer met during data transmission, the communication control unit 16 will instruct the data processing unit 12 to stop transmitting data to other connected wireless communication devices. This allows the wireless communication device 10 to immediately stop data transmission if it moves outside the communication area with other connected wireless communication devices.

[0037] The communication control unit 16 may also maintain a table in which the relationship between the round-trip time of a signal and the estimated transmission distance is associated in advance, and acquire distance information indicating the transmission distance based on the round-trip time measured by the round-trip time measurement unit 15.

[0038] Antenna 17 is provided in correspondence with the wireless communication unit 13. Antenna 17 radiates electrical signals (e.g., data or round-trip time measurement signals) output from the wireless communication unit 13 as radio waves. Antenna 17 receives radio waves transmitted from other wireless communication devices. Antenna 17 may form directional beams in different directions.

[0039] (Operation of Wireless Communication Device 10) Figure 2 is a flowchart showing the processing flow of the wireless communication device 10 in the second embodiment. The communication control unit 16 of the wireless communication device 10 determines whether or not the wireless communication unit 13 is connected to another wireless communication device (step S101). If the communication control unit 16 determines that the wireless communication unit 13 is not connected to another wireless communication device (step S101-NO), the communication control unit 16 repeatedly executes the process in step S101.

[0040] On the other hand, if the communication control unit 16 determines that the wireless communication unit 13 is connected to another wireless communication device (step S101-YES), the communication control unit 16 sends a measurement signal transmission instruction to the round-trip time measurement signal transmission unit 14. As a result, the communication control unit 16 instructs the round-trip time measurement signal transmission unit 14 to transmit the round-trip time measurement signal (step S102). The round-trip time measurement signal transmission unit 14 generates a round-trip time measurement signal in response to the measurement signal transmission instruction sent from the communication control unit 16. The round-trip time measurement signal transmission unit 14 outputs the generated round-trip time measurement signal to the wireless communication unit 13. The round-trip time measurement signal transmission unit 14 instructs the round-trip time measurement unit 15 to measure the round-trip time at the timing when it outputs the round-trip time measurement signal to the wireless communication unit 13. The round-trip time measurement unit 15 acquires the timing when it was instructed by the round-trip time measurement signal transmission unit 14 to measure the round-trip time as the transmission time of the round-trip time measurement signal.

[0041] The wireless communication unit 13 transmits the round-trip time measurement signal output from the round-trip time measurement signal transmission unit 14 to another wireless communication device via the antenna 17. After that, the wireless communication device 10 waits for a certain period of time (step S103). The communication control unit 16 determines whether or not a response to the round-trip time measurement signal has been received during the waiting period or after the waiting period (step S104).

[0042] If the communication control unit 16 determines that it has not received a response to the round-trip time measurement signal (step S104-NO), the communication control unit 16 repeats the process in step S102. In this case, the round-trip time measurement unit 15 obtains the timing at which it is newly instructed by the round-trip time measurement signal transmission unit 14 to measure the round-trip time as the transmission time of the round-trip time measurement signal.

[0043] When the communication control unit 16 determines that it has received a response to the round-trip time measurement signal (step S104 - YES), the wireless communication unit 13 outputs the received response to the round-trip time measurement unit 15. The round-trip time measurement unit 15 acquires, as the reception time of the response to the round-trip time measurement signal, the timing at which the response to the round-trip time measurement signal is obtained via the wireless communication unit 13. The round-trip time measurement unit 15 measures the round-trip time based on the transmission time and the reception time. The round-trip time measurement unit 15 outputs information indicating the measured round-trip time to the communication control unit 16.

[0044] The communication control unit 16 estimates the transmission distance between the wireless communication device 10 and another wireless communication device based on the information indicating the round-trip time output from the round-trip time measurement unit 15 and the speed of light (step S105). The communication control unit 16 determines whether or not the data transmission conditions are satisfied based on the estimated transmission distance (step S106). The communication control unit 16 determines that the data transmission conditions are not satisfied when the transmission distance is outside a predetermined range. The communication control unit 16 determines that the data transmission conditions are satisfied when the transmission distance is within a predetermined range.

[0045] When the communication control unit 16 determines that the data transmission conditions are not satisfied (step S106 - NO), the wireless communication device 10 is not located within an appropriate area of the wireless communication method of the wireless communication unit 13. In this case, the wireless communication device 10 regards that there is a possibility that the transmission quality deteriorates and executes the process of step S101 without performing data transmission.

[0046] On the other hand, when the communication control unit 16 determines that the data transmission condition is satisfied (step S106 - YES), the communication control unit 16 determines whether there is data to be transmitted in the data storage unit 11 (step S107). When the communication control unit 16 determines that there is no data to be transmitted in the data storage unit 11 (step S107 - NO), since there is no need for the wireless communication device 10 to transmit data, the process of step S101 is executed. In this case, instead of immediately executing the process of step S101, the wireless communication device 10 may execute the process of step S101 at the timing when data is accumulated in the data storage unit 11. Thereby, it is possible to suppress the transmission of the round-trip time measurement signal in a situation where there is no data to be transmitted (suppress the processing load on the wireless communication device 10), and it is also possible to suppress the influence on the communication being performed around the wireless communication device 10.

[0047] When the communication control unit 16 determines that there is data to be transmitted in the data storage unit 11 (step S107 - YES), the communication control unit 16 transmits a data transmission instruction to the data processing unit 12. Thereby, the communication control unit 16 instructs the data processing unit 12 to transmit the data stored in the data storage unit 11 (step S108). The data processing unit 12 reads out data from the data storage unit 11 according to the data transmission instruction transmitted from the communication control unit 16 and outputs it to the wireless communication unit 13. The wireless communication unit 13 wirelessly transmits the data output from the data processing unit 12 to another connected wireless communication device.

[0048] According to the wireless communication device 10 configured as described above, when the data transmission condition is satisfied, it includes a communication control unit 16 that instructs data transmission to another connected wireless communication device, and a wireless communication unit 13 that wirelessly performs data transmission to another connected wireless communication device in response to the instruction of the communication control unit 16.

[0049] This allows the wireless communication device 10 to transmit data only when it is within the communication area of ​​other connected wireless communication devices and communication is expected to be stable. If the wireless communication device 10 is outside the communication area of ​​other connected wireless communication devices (for example, when it moves and goes outside the communication area), the wireless communication device 10 will not transmit data. This prevents interruptions in data transmission and the resulting interference to surrounding wireless communication devices. Therefore, it is possible to suppress a decrease in wireless transmission efficiency.

[0050] (Second Embodiment) In the first embodiment, a configuration in which the wireless communication device comprises one wireless communication unit was described. In contrast, it is conceivable to provide redundancy for wireless communication links by having a wireless communication device comprising multiple wireless communication units and controlling each wireless communication unit to connect to another wireless communication device (for example, a base station device) (see, for example, Patent Document 1). Therefore, in the second embodiment, a configuration in which the wireless communication device comprises multiple wireless communication units and performs wireless communication with multiple wireless communication devices will be described.

[0051] (Configuration of Wireless Communication Device 10a) Figure 3 shows an example of the configuration of the wireless communication device 10a in the second embodiment. The wireless communication device 10a includes a data storage unit 11, a data processing unit 12, a plurality of wireless communication units 13-1 to 13-2, a round-trip time measurement signal transmission unit 14a, a round-trip time measurement unit 15a, a communication control unit 16a, and a plurality of antennas 17-1 to 17-2. Although Figure 3 shows a configuration in which the wireless communication device 10a has two wireless communication units 13 and antennas 17, the wireless communication device 10a may be configured to have three or more wireless communication units 13 and antennas 17.

[0052] The wireless communication device 10a estimates the transmission distance based on the responses received through each of the multiple wireless communication units 13-1 to 13-2 using the method shown in the first embodiment. The wireless communication device 10a transmits the data stored in the data storage unit 11 if either or both of the transmission distances obtained based on the responses received by each wireless communication unit 13 are within a predetermined range, and does not transmit data if both are outside the predetermined range. In other words, the wireless communication device 10a transmits data if either or both of the transmission distances obtained based on the responses received by each wireless communication unit 13 satisfy the data transmission conditions, and does not transmit data if neither satisfies the data transmission conditions.

[0053] Furthermore, performing data transmission only when both transmission distances obtained based on responses received by multiple wireless communication units 13-1 to 13-2 are within a predetermined range means that data transmission is performed only under conditions where the wireless communication device 10a is unlikely to move outside the predetermined range. Performing data transmission when either of the transmission distances obtained based on responses received by multiple wireless communication units 13-1 to 13-2 is within a predetermined range means that data transmission is actively performed under conditions where even a small amount of data can be expected.

[0054] The wireless communication units 13-1 and 13-2 may communicate with the same other wireless communication device, or with different other wireless communication devices. The wireless communication units 13-1 and 13-2 may communicate with the same or different other wireless communication devices using, for example, a wireless communication method using a high frequency band (e.g., 3GPP, 5G NR, or IEEE 802.11ad).

[0055] The wireless communication units 13-1 and 13-2 transmit, for example, the round-trip time measurement signal output from the round-trip time measurement signal transmission unit 14a to the same or different other wireless communication devices via antennas 17-1 and 17-2. When the wireless communication units 13-1 and 13-2 receive a response to the round-trip time measurement signal from another connected wireless communication device, they output the received response to the round-trip time measurement signal to the round-trip time measurement unit 15a.

[0056] Furthermore, the wireless communication units 13-1 and 13-2 transmit the data output from the data processing unit 12 to other connected wireless communication devices via the antennas 17-1 and 17-2.

[0057] The wireless communication units 13-1 and 13-2 may control the amplitude or phase of the antennas 17 and 17-2 to form directional beams in different directions, according to instructions from the communication control unit 16a. The wireless communication units 13-1 and 13-2 switch the directional beams and transmit signals according to instructions from the communication control unit 16a. The wireless communication units 13-1 and 13-2 receive signals (e.g., responses) transmitted from other wireless communication devices via the antennas 17-1 and 17-2.

[0058] The round-trip time measurement signal transmission unit 14a generates a round-trip time measurement signal in response to a measurement signal transmission instruction from the communication control unit 16a, and outputs the generated round-trip time measurement signal to the wireless communication units 13-1 and 13-2. The round-trip time measurement signal transmission unit 14a instructs the round-trip time measurement unit 15a to measure the round-trip time at the timing when the round-trip time measurement signal is output.

[0059] The round-trip time measurement unit 15a measures the round-trip time from the transmission time of the round-trip time measurement signal to the reception time of the response to the round-trip time measurement signal, in response to instructions from the round-trip time measurement signal transmission unit 14a. The round-trip time measurement unit 15a acquires the timing at which the response to the round-trip time measurement signal is obtained via the wireless communication units 13-1 and 13-2, respectively, as the reception time of the response to the round-trip time measurement signal. The round-trip time measurement unit 15a measures the round-trip time based on the transmission time and the reception time. For example, the round-trip time measurement unit 15a measures the difference between the transmission time and the reception time as the round-trip time.

[0060] In this embodiment, the wireless communication device 10a is equipped with multiple wireless communication units 13. Therefore, the round-trip time measurement unit 15a needs to distinguish between the wireless communication units 13 and measure the round-trip time for each unit. The round-trip time measurement unit 15a adds identification information to the measured round-trip time to identify the wireless communication unit 13 and outputs it to the communication control unit 16a. This allows the communication control unit 16a to estimate the transmission distance for each wireless communication unit 13.

[0061] The communication control unit 16a controls the operation of the data processing unit 12, the wireless communication units 13-1 and 13-2, and the round-trip time measurement signal transmission unit 14a. For example, if the wireless communication units 13-1 and 13-2 are connected to other wireless communication devices, the communication control unit 16a sends a measurement signal transmission instruction to the round-trip time measurement signal transmission unit 14a to transmit a round-trip time measurement signal. Furthermore, based on the round-trip time measured by the round-trip time measurement unit 15a, the communication control unit 16a estimates the transmission distance between its own device and the other connected wireless communication device for each wireless communication unit 13.

[0062] The communication control unit 16a estimates the transmission distance between the wireless communication device 10a and other wireless communication devices connected to the wireless communication unit 13-1, for example, using the round-trip time and the speed of light obtained based on the response received by the wireless communication unit 13-1. The communication control unit 16a also estimates the transmission distance between the wireless communication device 10a and other wireless communication devices connected to the wireless communication unit 13-2, for example, using the round-trip time and the speed of light obtained based on the response received by the wireless communication unit 13-2. In this way, the communication control unit 16a acquires distance information indicating the transmission distance for each wireless communication unit 13. The communication control unit 16a determines whether the data transmission conditions have been met based on the estimated transmission distance for each wireless communication unit 13.

[0063] The communication control unit 16a checks whether there is data to be transmitted in the data storage unit 11 when one or both of the transmission distances of each wireless communication unit 13 meet the data transmission conditions. If there is data to be transmitted in the data storage unit 11, the communication control unit 16a instructs the data processing unit 12 to transmit the data to another connected wireless communication device. At this time, the communication control unit 16a instructs the wireless communication unit 13 that has met the data transmission conditions to transmit the data to be transmitted.

[0064] On the other hand, the communication control unit 16a will not transmit data if both the transmission distance of each wireless communication unit 13 does not meet the data transmission conditions. For example, if the data transmission conditions are no longer met during data transmission, the communication control unit 16a will instruct the data processing unit 12 to stop data transmission to other connected wireless communication devices. This allows data transmission to be stopped immediately if the wireless communication device 10a moves outside the communication area with other connected wireless communication devices.

[0065] The communication control unit 16a may also maintain a table in which the relationship between the round-trip time of a signal and the estimated transmission distance is associated, and acquire distance information indicating the transmission distance based on the round-trip time measured by the round-trip time measurement unit 15a.

[0066] With the wireless communication device 10a configured as described above, the same effects as in the first embodiment can be obtained.

[0067] (Modification 1 common to the first and second embodiments) In the embodiments described above, the example was given of a case in which the decision to transmit data based on the estimated communication distance is made within the wireless communication device. However, the estimation of the communication distance and the decision to transmit data may be made by a dedicated aggregation device. That is, the wireless communication device may transmit the information of the estimated communication distance to another aggregation device by wired or wireless communication, and the aggregation device may make a decision on switching the communication method and instruct the wireless communication device to switch. Furthermore, the example was given of a case in which the wireless communication device includes a data storage unit and temporarily stores data from the outside before transmitting the data. However, the data storage unit may be located outside the wireless communication device, and even if no data is stored, real-time generated video data may be transmitted. All of these are included in the present invention.

[0068] (Modification 2 common to the first and second embodiments) In the embodiments described above, terminal devices that are generally equipped on people or machines and are often mobile, or base station devices that are generally stationary on the ground and have a communication path to an external network such as the Internet, were described collectively as wireless communication devices without much distinction. This is because the present invention is applicable to either of them, but of course, the present invention may be applied to either one of them.

[0069] For example, the terminal device may estimate the transmission distance and autonomously transmit data, or it may transmit data or real-time video stored in an external device connected to the terminal device. In this configuration, the terminal device is the wireless communication device 10, 10a described above.

[0070] For example, a terminal device (first communication device) may estimate the transmission distance, transmit the estimated transmission distance information to a base station device (second communication device), and the base station device, or its higher-level aggregation device (second communication device), may determine whether the data transmission conditions are met based on the transmission distance information and perform data transmission. In this configuration, the terminal device has functions other than determining whether the data transmission conditions are met in the configuration shown in the wireless communication devices 10, 10a. The base station device, or its higher-level aggregation device, also has a function (communication control unit 16, 16a) that determines whether the transmission distance transmitted from the terminal device meets the data transmission conditions, and a function (wireless communication unit 13, 13-1 to 13-2) that transmits data. The base station device, or its higher-level aggregation device, then checks whether there is data to be transmitted if the data transmission conditions are met. If there is data to be transmitted, the base station device, or its higher-level aggregation device, transmits the data to the terminal device (first communication device).

[0071] Furthermore, the base station device may estimate the transmission distance to the terminal device, and the base station device, or a higher-level aggregation device, may determine whether the data transmission conditions are met based on the estimated transmission distance and then perform data transmission between the base station device and the terminal device. In this configuration, the base station device has at least functions other than determining whether the data transmission conditions are met in the configuration shown in the wireless communication devices 10 and 10a. When the base station device determines whether the data transmission conditions are met based on the estimated transmission distance, the base station device also has a function to determine whether the data transmission conditions are met. When a higher-level aggregation device determines whether the data transmission conditions are met based on the estimated transmission distance, the higher-level aggregation device has a function to determine whether the data transmission conditions are met.

[0072] (Modification 3 common to the first and second embodiments) In wireless communication systems using high frequency bands, signals are sometimes transmitted by beamforming, which focuses the energy of radio waves in a specific directional direction. In addition, when communication uses a reflected path, the estimated transmission distance may fluctuate significantly even within the area due to the temporary use of the reflected path. In particular, when a reflected path is used, the transmission distance obtained may be significantly different from the direct transmission distance between wireless communication devices. To eliminate this effect, the wireless communication devices 10 and 10a may perform averaging processing on the estimated transmission distance or perform outlier filtering processing.

[0073] In this configuration, the wireless communication devices 10 and 10a estimate the transmission distance multiple times at different timings and estimate the transmission distance used to determine the data transmission conditions based on the multiple estimated transmission distances. In other words, the wireless communication devices 10 and 10a acquire distance information indicating the transmission distance based on the results of multiple measurements taken at different timings.

[0074] First, let's explain the case where averaging is performed. In this case, the communication control units 16 and 16a store in advance multiple estimated transmission distance values ​​and obtain the average value of the multiple stored transmission distance values ​​as the final transmission distance. The communication control units 16 and 16a determine whether the data transmission conditions are met based on the calculated average value. The communication control units 16 and 16a determine that the data transmission conditions are met if the calculated average value is within a predetermined range. The communication control units 16 and 16a determine that the data transmission conditions are not met if the calculated average value is not within a predetermined range (outside the predetermined range).

[0075] Next, we will explain the process of filtering outliers. In this case, the communication control units 16 and 16a store in advance multiple estimated transmission distance values ​​and calculate the median of the multiple stored transmission distances. The communication control units 16 and 16a extract multiple transmission distance values ​​from the multiple transmission distance values ​​that are within a certain range relative to the calculated median. In this way, the communication control units 16 and 16a remove values ​​that are outside a certain range from the median from the multiple transmission distance values. The communication control units 16 and 16a obtain the average value of the extracted multiple transmission distance values ​​(transmission distance values ​​within a certain range relative to the median) as the final transmission distance. The communication control units 16 and 16a determine whether the data transmission conditions have been met based on the calculated average value. The communication control units 16 and 16a determine that the data transmission conditions have been met if the calculated average value is within a predetermined range. The communication control units 16 and 16a determine that the data transmission conditions have not been met if the calculated average value is not within a predetermined range (outside the predetermined range).

[0076] (Modification 4 common to the first and second embodiments) The communication control units 16, 16a may perform prediction processing such as linear extrapolation on the transmission distance to predict that it will fall within a predetermined range.

[0077] With respect to the wireless communication devices 10, 10a shown in each of the embodiments described above, the following additional notes are disclosed. (Note 1) The transmission distance is calculated based on the average value of a plurality of estimated transmission distances estimated by the communication control units 16, 16a. (Note 2) The transmission distance is calculated by excluding outliers that are outside the specified range from a plurality of estimated transmission distances estimated by the communication control units 16, 16a.

[0078] In each of the embodiments described above, some or all of the functional units of the wireless communication devices 10, 10a (for example, wireless communication units 13, 13-1 to 13-2, round-trip time measurement signal transmission unit 14, round-trip time measurement signal transmission unit 14a, round-trip time measurement units 15, 15a, and communication control units 16, 16a) are implemented as software by one or more processors such as a CPU (Central Processing Unit) executing a program stored in a storage device and memory having a non-volatile recording medium (non-temporary recording medium). The program may be recorded on a computer-readable non-temporary recording medium. A computer-readable non-temporary recording medium is, for example, a portable medium such as a flexible disk, magneto-optical disk, ROM (Read Only Memory), CD-ROM (Compact Disc-ROM), or a storage device such as a hard disk built into a computer system.

[0079] Some or all of the functional parts of the wireless communication devices 10, 10a may be implemented using hardware including electronic circuits (or circuits) such as LSI (Large Scale Integrated Circuit), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), or FPGA (Field Programmable Gate Array).

[0080] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of this invention.

[0081] This invention can be applied to wireless communication devices that communicate wirelessly with one or more other wireless communication devices.

[0082] 10, 10a... Wireless communication device, 11... Data storage unit, 12... Data processing unit, 13, 13-1 to 13-2... Wireless communication unit, 14, 14a... Round-trip time measurement signal transmission unit, 15, 15a... Round-trip time measurement unit, 16, 16a... Communication control unit, 17, 17-1 to 17-2... Antenna

Claims

1. A wireless communication device comprising: a communication control unit that instructs data transmission to a peer device when the condition is met that the transmission distance between the peer device and the peer device during wireless communication is within a predetermined range; and one or more wireless communication units that wirelessly transmit the data to the peer device in response to the instruction of the communication control unit.

2. A wireless communication system comprising a first communication device and a second communication device that performs wireless communication with the first communication device, wherein the first communication device acquires information indicating the transmission distance between itself and the second communication device during wireless communication, and transmits the acquired information indicating the transmission distance to the second communication device, and the second communication device comprises a communication control unit that, based on the information indicating the transmission distance transmitted from the first communication device, instructs the first communication device to transmit data when the condition that the transmission distance is within a predetermined range is met, and one or more wireless communication units that perform the data transmission to the first communication device wirelessly in response to the instruction of the communication control unit.

3. A wireless communication method that, when the condition is met that the transmission distance between the connected wireless communication device and the opposing device is within a predetermined range, instructs the opposing device to transmit data, and transmits the data wirelessly to the opposing device in response to the instruction.

4. A program for causing a computer to execute: a communication control step that instructs data transmission to a peer device when the condition is met that the transmission distance between the computer and the peer device during wireless communication is within a predetermined range; and a wireless communication step that performs the data transmission to the peer device wirelessly in response to the instruction in the communication control step.

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