Wireless communication device and wireless communication method

Abstract

To secure communication quality and to make it less likely to be in an out-of-service state.SOLUTION: A wireless communication device comprises: a first communication unit that communicates with a base station; a second communication unit that communicates with other wireless communication device; an electric wave strength measurement unit that measures a reception electric wave strength value of an electric wave received from a first base station; a base station search unit that searches a newly connected base station by controlling the first communication unit on the basis of the reception electric wave strength value; a communication control unit that controls the first communication unit and the second communication unit; and a mode setting unit that selectively sets a first mode and a second mode which is different from the first mode. In the first mode, the base station search unit searches a base station which is a new connection destination when the reception electric wave strength value is lower than a preset first threshold value. The communication control unit switches a base station to be connected from the first base station to a second base station when information of the second base station is received from other wireless communication device, the information received at a reception electric wave strength that is more than or equal to a preset second threshold value being larger than the first threshold value.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Techniques for controlling the connection between a wireless communication device and a base station are known. For example, Patent Document 1 describes a technique capable of shortening the search time of a base station.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the communication quality of a wireless communication device falls below a predetermined value, the communication with the current base station is terminated, and another base station with better communication quality is searched for. However, there is an area with weak electric field where the communication quality from any base station is below the predetermined value. In this area, the wireless communication device enters an out-of-service state because it terminates the communication with the base station. The wireless communication device can make it difficult to enter the out-of-service state by lowering the threshold value, which is the predetermined value of the communication quality at which the search is started. However, lowering the threshold value may cause a deterioration in communication quality because it does not search for a base station with better communication quality.

[0005] An object of the present invention is to provide a wireless communication device and a wireless communication method that ensure communication quality and are less likely to enter an out-of-service state.

Means for Solving the Problems

[0006] The wireless communication device according to the present invention comprises: a first communication unit that communicates with a base station using a first wireless communication method; a second communication unit that communicates with other wireless communication devices using a second wireless communication method; a radio wave intensity measurement unit that measures the received radio wave intensity value of the radio waves received by the first communication unit from the first base station; a base station search unit that controls the first communication unit to search for a new base station to connect to based on the received radio wave intensity value measured by the radio wave intensity measurement unit; a communication control unit that controls the first communication unit and the second communication unit; and a mode setting unit that selectively sets a first mode and a second mode different from the first mode. When the mode setting unit is set to the first mode, the base station search unit searches for a new base station to connect to when the received radio wave intensity value measured by the radio wave intensity measurement unit falls below a preset first threshold, and the communication control unit switches the base station to connect to from the first base station to the second base station when it receives information of a second base station received with a received radio wave intensity of a preset second threshold or higher than the first threshold from another wireless communication device via the second communication unit.

[0007] The wireless communication method according to the present invention includes the steps of: a first communication unit communicating with a base station using a first wireless communication method; a second communication unit communicating with another wireless communication device using a second wireless communication method; measuring the received signal strength value of radio waves received from the first base station; controlling the first communication unit to search for a new base station to connect to based on the measured received signal strength value; controlling the first communication unit and the second communication unit; selectively setting a first mode and a second mode different from the first mode; searching for a new base station to connect to when the first mode is set and the measured received signal strength value falls below a preset first threshold; and switching the base station to connect to from the first base station to the second base station when information of a second base station received with a received signal strength of a preset second threshold greater than the first threshold is received from another wireless communication device via the second communication unit. [Effects of the Invention]

[0008] According to the present invention, communication quality can be ensured, and the device is less likely to be out of range. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an example of the configuration of a wireless communication system according to the first embodiment. [Figure 2] Figure 2 is a block diagram showing an example configuration of a wireless communication device according to the first embodiment. [Figure 3] Figure 3 is a sequence diagram showing the processing flow of the wireless communication system according to the embodiment. [Figure 4] Figure 4 is a diagram illustrating a method for changing the RSSI value threshold from a reference threshold to a first threshold according to the embodiment. [Figure 5] Figure 5 is a diagram illustrating a method for setting the second threshold value of the RSSI value according to the embodiment. [Figure 6] Figure 6 is a diagram illustrating a method for setting the third threshold value of the RSSI value according to the embodiment. [Figure 7] Figure 7 is a flowchart showing the processing flow of a wireless communication device according to an embodiment of this invention. [Figure 8] Figure 8 is a flowchart showing the processing flow of a wireless communication device according to an embodiment of this invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the attached drawings. However, the present invention is not limited by these embodiments, and in the following embodiments, the same parts are denoted by the same reference numerals to omit redundant explanations.

[0011] [First Embodiment] (Wireless communication system) An example of the configuration of the wireless communication system according to the first embodiment will be described using Figure 1. Figure 1 is a diagram showing an example of the configuration of the wireless communication system according to the first embodiment.

[0012] As shown in Figure 1, the wireless communication system 1 includes wireless communication device 10-1 and wireless communication device 10-2. Wireless communication device 10-1 and wireless communication device 10-2 are communicated with each other via network N. When there is no need to distinguish between wireless communication device 10-1 and wireless communication device 10-2, they may be collectively referred to as wireless communication device 10.

[0013] Wireless communication device 10-1 is connected to a first base station. Wireless communication device 10-2 is connected to a second base station, which includes the first base station. Wireless communication device 10-1 is configured to change the base station it is connected to from the first base station to the second base station based on first received signal strength information, which includes information about the first base station and the first received signal strength of the radio waves received from the first base station, and second received signal strength information, which includes information about the second base station received from wireless communication device 10-2 and the second received signal strength of the radio waves received from the second base station. The base station information includes, for example, information about the frequency and identifier used by the base station.

[0014] The wireless communication devices 10-1 and 10-2 are, for example, commercial wireless communication devices, but are not limited to these. One of the wireless communication devices 10-1 and 10-2 may be an in-vehicle device and the other a handheld wireless communication device. The wireless communication devices 10-1 and 10-2 may be owned by the same user or by different users. It is preferable that the wireless communication devices 10-1 and 10-2 are placed in close proximity and that the environment for measuring the received signal strength of the radio waves received from the base station is the same.

[0015] (Wireless communication device) The wireless communication device according to the first embodiment will be described using Figure 2. Figure 2 is a block diagram showing an example of the configuration of the wireless communication device according to the first embodiment.

[0016] As shown in FIG. 2, the wireless communication device 10 includes a first communication unit 12, a second communication unit 14, an operation unit 16, a display unit 18, an audio output unit 20, a storage unit 22, a GNSS (Global Navigation Satellite System) 24, and a control unit 26.

[0017] The first communication unit 12 communicates with a base station using a long-distance wireless communication method. The long-distance wireless communication method is a type of the first wireless communication method. Examples of the long-distance wireless communication method include digital trunked radio such as APCO-P25 (Association of Public safety Communications Officials international Project 25) and NXDN (registered trademark). The long-distance wireless communication method may also be communication via a mobile phone network or the like.

[0018] The second communication unit 14 communicates with other wireless communication devices 10 using a short-distance wireless communication method. The short-distance wireless communication method is a type of the second wireless communication method. The network N in FIG. 1 is communicably connected, for example, by the second communication unit 14 of the wireless communication device 10-1 and the second communication unit 14 of the wireless communication device 10-2. Examples of the short-distance wireless communication method include, but are not limited to, communication using Wi-Fi (registered trademark) and Bluetooth (registered trademark). The second communication unit 14 may also be wired communication.

[0019] The operation unit 16 receives various input operations on the wireless communication device 10. The operation unit 16 outputs an operation signal corresponding to the received input operation to the control unit 26. The operation unit 16 includes, for example, a touch panel, buttons, switches, a microphone, and the like. When a touch panel is used as the operation unit 16, the operation unit 16 is disposed on the display unit 18.

[0020] The display unit 18 displays various images. The display unit 18 is, for example, a display including a liquid crystal display (LCD) or an organic EL (Electro-Luminescence).

[0021] The audio output unit 20 is a speaker that outputs various types of audio. For example, the audio output unit 20 outputs the voice of the person on the other end of the call.

[0022] The memory unit 22 stores various types of information. The memory unit 22 stores the calculation contents of the control unit 26 and information such as programs. The memory unit 22 includes, for example, at least one of the following: RAM (Random Access Memory), main memory such as ROM (Read Only Memory), and external memory such as HDD (Hard Disk Drive).

[0023] The GNSS receiving unit 24 consists of a GNSS receiver and other components that receive GNSS signals from GNSS satellites. The GNSS receiving unit 24 outputs the received GNSS signals to the control unit 26.

[0024] The control unit 26 controls each part of the wireless communication device 10. The control unit 26 includes, for example, an information processing device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and a storage device such as RAM (Random Access Memory) or ROM (Read Only Memory). The control unit 26 executes a program that controls the operation of the wireless communication device 10 according to the present invention. The control unit 26 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 26 may be implemented by a combination of hardware and software.

[0025] The control unit 26 comprises a communication control unit 30, a base station search unit 32, a radio wave strength measurement unit 34, and a mode setting unit 36.

[0026] The communication control unit 30 controls the first communication unit 12 and the second communication unit 14. The communication control unit 30 controls the first communication unit 12 to communicate with the base station. The communication control unit 30 controls the first communication unit 12 to change the base station that communicates with the wireless communication device 10. The communication control unit 30 controls the second communication unit 14 to communicate with other wireless communication devices 10.

[0027] The base station search unit 32 searches for a base station that communicates with the wireless communication device 10. The base station search unit 32 searches for a base station that communicates with the wireless communication device 10 via the first communication unit 12.

[0028] The radio wave strength measurement unit 34 measures the received radio wave strength related to the radio waves from the base station received by the first communication unit 12. For example, the radio wave strength measurement unit 34 measures the received radio wave strength related to the radio waves from the base station received by the first communication unit 12. Measure the RSSI (Received Signal Strength Indicator) value.

[0029] The mode setting unit 36 ​​sets the operating mode of the wireless communication device 10 for multiple wireless communication devices 10 to cooperate in changing the base station to which they connect. The first mode set by the mode setting unit 36 ​​is a mode in which the wireless communication device 10 changes the base station to which it connects based on the received signal strength of the radio waves received from the base station to which it is connected and the received signal strength of other base stations included in the received signal strength information provided by other wireless communication devices 10. The second mode set by the mode setting unit 36 ​​is a mode in which the wireless communication device 10 provides the received signal strength information of the base station discovered by the wireless communication device 10 to the wireless communication device 10 set to the first mode. The mode setting unit 36 ​​selectively sets the first mode and the second mode to the wireless communication device 10.

[0030] (Processing of wireless communication systems) The processing details of the wireless communication system according to the embodiment will be explained using Figure 3. Figure 3 is a sequence diagram showing the processing flow of the wireless communication system according to the embodiment.

[0031] The example shown in Figure 3 illustrates the processing flow between wireless communication device 10-1 and wireless communication device 10-2. In the example shown in Figure 3, wireless communication device 10-1 is set to the first mode by the mode setting unit 36. Wireless communication device 10-1 is a wireless communication device 10 that performs voice communication and data communication with a base station, and is a wireless communication device that uses received radio wave strength information provided by wireless communication device 10-2 in the process of changing the base station to which it communicates. Line communication device 10-2 is set to the second mode by the mode setting unit 36. In this case, wireless communication device 10-2 provides wireless communication device 10-1 with received radio wave strength information of a base station that wireless communication device 10-2 has searched for in order to change the base station to which wireless communication device 10-1 communicates. Figure 3 shows the process up to when wireless communication device 10-1 determines the base station to which it connects.

[0032] The wireless communication device 10-1 generates a pairing request signal to establish a connection to the network N shown in Figure 1, which communicates with wireless communication device 10-2 in order to change the base station to communicate with (step S10). The request signal includes a signal requesting pairing to obtain received signal strength information in order to change the base station to communicate with. Then, the process proceeds to step S12.

[0033] The wireless communication device 10-1 transmits the generated request signal to the wireless communication device 10-2 (step S12). Then, the process proceeds to step S14.

[0034] The wireless communication device 10-2 receives a request signal from the wireless communication device 10-1 (step S14). Then, the process proceeds to step S16.

[0035] The wireless communication device 10-2 generates a response signal to the request signal (step S16). If the wireless communication device 10-2 permits the request for pairing with the wireless communication device 10-1, it generates a response signal indicating that pairing is permitted. If the wireless communication device 10-2 rejects pairing with the wireless communication device 10-2, it generates a response signal indicating that pairing is rejected. In the example shown in Figure 3, the wireless communication device 10-2 generates a response signal indicating that pairing is permitted. Then, the process proceeds to step S18.

[0036] The wireless communication device 10-2 transmits the generated response signal to the wireless communication device 10-1 (step S18). Then, the process proceeds to step S20.

[0037] The wireless communication device 10-1 receives a response signal from the wireless communication device 10-2 (step S20). Pairing is completed when the wireless communication device 10-1 receives a response signal from the wireless communication device 10-2 indicating permission for pairing. Then, the process proceeds to step S22.

[0038] The wireless communication device 10-1 changes the RSSI value threshold used to determine when to search for a base station from a reference threshold to a first threshold (step S22). Figure 4 is a diagram illustrating the method of changing the RSSI value threshold from a reference threshold to a first threshold according to the embodiment. In Figure 4, the horizontal axis represents position and the vertical axis represents the RSSI value. Waveform W1 shows the RSSI value of the first base station with which the wireless communication device 10-1 is communicating. Waveform W2 shows the RSSI value of a second base station different from the first base station. Point P1 shows the RSSI value of the first base station at the current location of the wireless communication device 10-1. The reference threshold is a threshold value that is the reference value of the RSSI value that triggers the wireless communication device 10-1 to start searching for a base station independently when it is not connected to the wireless communication device 10-2. Normally, the wireless communication device 10-1 determines that it is necessary to search for a new base station to communicate with when the RSSI value falls below the reference threshold. Once pairing with wireless communication device 10-2 is complete, wireless communication device 10-1 changes the reference value of the RSSI value from the reference threshold to the first threshold. In other words, wireless communication device 10-1 makes it difficult to change the base station with which it communicates. As a result, wireless communication device 10-1 continues to connect with the first base station even if the RSSI value of the first base station falls below the reference value. This is because even if wireless communication device 10-1 searches for other base stations immediately after the reference threshold falls below, it is not guaranteed that a better base station will be found, so it maintains the connection with the current base station even if the communication quality deteriorates. Then, the process proceeds to step S24.

[0039] The wireless communication device 10-1 sets a second threshold (step S24). Figure 5 is a diagram illustrating the method for setting the second threshold of the RSSI value according to the embodiment. In Figure 5, the horizontal axis represents position and the vertical axis represents the RSSI value. As shown in Figure 5, the wireless communication device 10-1 sets a second threshold that is greater than the first threshold. The second threshold is set to be greater than the first threshold and greater than the reference threshold. The wireless communication device 10-1 determines to change the connection from the first base station to the second base station if the second received radio wave strength of the second base station received from the wireless communication device 10-2 is greater than or equal to the second threshold and is greater than the received radio wave strength of the first base station to which the wireless communication device 10-1 is connected. This means that if there is a base station with a stronger received radio wave strength, the wireless communication device 10-1 can move earlier and maintain good communication quality. Then, the process proceeds to step S26.

[0040] The wireless communication device 10-2 sets a third threshold (step S26). Figure 6 is a diagram illustrating the method for setting the third threshold of the RSSI value according to the embodiment. In Figure 6, the horizontal axis represents position and the vertical axis represents the RSSI value. Points P2-1 and P2-2 represent the RSSI values ​​of the first base station at the corresponding positions of the wireless communication device 10-2. Point P2-3 represents the RSSI value of the second base station at the corresponding positions of the wireless communication device 10-2. As shown in Figure 6, the wireless communication device 10-2 sets a third threshold that is greater than the first threshold. The third threshold is set to be greater than the reference threshold and greater than or equal to the second threshold. If the RSSI value of the currently connected base station falls below the third threshold, the wireless communication device 10-2 searches for other base stations and changes its connection to another base station with a larger RSSI value. In the example in Figure 6, the wireless communication device 10-2 is initially connected to the first base station and receives the RSSI value signal of waveform W1 at the position of point P2-1. Next, the wireless communication device 10-2 moves to the position of point P2-2 and, if the RSSI value of the signal from the first base station it is receiving has attenuated as shown in waveform W1 and fallen below the third threshold, searches for another base station with a larger RSSI value. As a result, it finds base station 2, which has a larger RSSI value as shown in waveform W2. Then, the wireless communication device 10-2 receives the signal of the RSSI value of waveform W2 at point P2-3. The wireless communication device 10-2 transmits the RSSI value of the second base station at point P2-3 as the second received signal strength along with the information of the discovered second base station to the wireless communication device 10-1. This makes it easier for the wireless communication device 10-1 to move to a base station with a larger RSSI value. Then, the process proceeds to step S28.

[0041] The wireless communication device 10-2 generates received radio wave strength information (step S28). The wireless communication device 10-2 generates received radio wave strength information that associates the information of the base station that transmitted the radio waves with the received radio wave strength related to the RSSI value of the radio waves received from the base station. Then, the process proceeds to step S30.

[0042] The wireless communication device 10-2 transmits the generated received radio wave strength information to the wireless communication device 10-1 (step S30). Then, the process proceeds to step S32.

[0043] The wireless communication device 10-1 receives received radio wave strength information from the wireless communication device 10-2 (step S32). Then, the process proceeds to step S34.

[0044] The wireless communication device 10-1 determines the base station to connect to based on the received signal strength of the base station it has received, the received signal strength included in the received signal strength information received from the wireless communication device 10-2, the first threshold, and the second threshold. Then, it terminates the process shown in Figure 3.

[0045] (Processing of wireless communication devices) The processing details of the wireless communication device according to the embodiment will be explained using Figure 7. Figure 7 is a flowchart showing the processing flow of the wireless communication device according to the embodiment.

[0046] The process shown in Figure 7 illustrates the processing flow of a wireless communication device 10 set to the first mode, which changes the base station connection. For example, at the start of the process shown in Figure 7, the wireless communication device 10 set to the first mode and another wireless communication device 10 set to the second mode are connected to the same first base station. For example, the other wireless communication device 10 set to the second mode may be connected to a second base station different from the first base station.

[0047] The communication control unit 30 changes the RSSI value threshold used to determine whether or not to search for a base station to connect to, based on the first received radio wave strength information, from a reference threshold to a first threshold lower than the reference threshold (step S100). The user of the wireless communication device 10 can set the first threshold to any value via the operation unit 16. Then, the process proceeds to step S102.

[0048] The communication control unit 30 sets a second threshold value greater than the first threshold as an RSSI value to determine whether or not to change the base station to connect to, based on the second received radio wave strength information (step S102). The user of the wireless communication device 10 can set the second threshold value to any value via the operation unit 16. Then, the process proceeds to step S104.

[0049] The communication control unit 30 determines, via the second communication unit 14, whether or not it has received second received signal strength information from another wireless communication device set to the second mode (step S104). If it is determined that the second received signal strength information has been received (step S104; Yes), the process proceeds to step S106. If it is not determined that the second received signal strength information has been received (step S104; No), the process proceeds to step S110.

[0050] If the result in step S104 is Yes, the radio wave strength measurement unit 34 determines whether the second received radio wave strength included in the second received radio wave strength information is equal to or greater than the second threshold (step S106). If it is determined that the second received radio wave strength is equal to or greater than the second threshold (step S106; Yes), the process proceeds to step S108. If it is determined that the second received radio wave strength is not equal to or greater than the second threshold (step S106; No), the process proceeds to step S110.

[0051] If the result in step S106 is determined to be Yes, the communication control unit 30 switches the base station connected to the wireless communication device 10 from the first base station to the second base station based on the base station information included in the second received radio wave strength information (step S108). That is, the wireless communication device 10 set to the first mode and the other wireless communication devices 10 set to the second mode are connected to the same second base station. The process shown in Figure 7 is then terminated.

[0052] If the result is No in step S104, or No in step S106, the radio wave strength measurement unit 34 measures the radio waves from the first base station (step S110). Specifically, the radio wave strength measurement unit 34 measures the first received radio wave strength of the radio waves received by the first communication unit 12 from the first base station to which the wireless communication device 10 is currently connected. Then, the process proceeds to step S112.

[0053] The radio wave strength measurement unit 34 determines whether the first received radio wave strength falls below the first threshold (step S112). If it is determined that the first received radio wave strength falls below the first threshold (step S112; Yes), the process proceeds to step S114. If it is not determined that the first received radio wave strength falls below the first threshold (step S112; No), the process shown in Figure 7 is terminated without changing the connected base station.

[0054] If the answer in step S112 is "Yes," the base station search unit 32 searches for a new base station to switch to from the first base station (step S114). Then, the process proceeds to step S116.

[0055] The radio wave strength measurement unit 34 determines whether or not there is a base station whose received radio wave strength is equal to or greater than the first threshold (step S116). If it is determined that there is a base station whose signal strength is equal to or greater than the first threshold (step S116; Yes), the process proceeds to step S118. If it is not determined that there is a base station whose signal strength is equal to or greater than the first threshold (step S116; No), the process proceeds to step S120.

[0056] If the result in step S116 is determined to be Yes, the communication control unit 30 switches the base station connected to the wireless communication device 10 from the first base station to a base station found by the base station search unit 32 whose received radio wave strength is equal to or greater than the first threshold (step S118). Here, if there are multiple base stations with a received radio wave strength equal to or greater than the first threshold, the communication control unit 30 switches the connection from the first base station to the base station that shows the maximum received radio wave strength among the multiple base stations. Then the process shown in Figure 7 is terminated.

[0057] If the result in step S116 is determined to be No, the wireless communication device 10 will transition to an out-of-range state because there are no base stations it can connect to (step S120). When the wireless communication device 10 transitions to an out-of-range state, it becomes unable to communicate. The process shown in Figure 7 then ends. Although not shown, the wireless communication device 10, in an out-of-range state, continues to search for base stations, and if it finds a base station that can receive signals with a received signal strength of 1 or higher, it restarts the process shown in Figure 7.

[0058] (Processing of wireless communication devices) The processing details of the wireless communication device according to the embodiment will be explained using Figure 8. Figure 8 is a flowchart showing the processing flow of the wireless communication device according to the embodiment.

[0059] The process shown in Figure 8 illustrates the processing flow of a wireless communication device 10 that is set to the second mode, which is set to the first mode and provides information to other wireless communication devices 10 that change the base station connection.

[0060] The communication control unit 30 sets a third threshold that is greater than the first threshold as the RSSI value used as a criterion for searching for a base station to provide received signal strength information to other wireless communication devices 10 that are set to the first mode and change the base station to which they are connected (step S130). The user of the wireless communication device 10 can set the third threshold to any value via the operation unit 16. Then the process proceeds to step S132.

[0061] The radio wave strength measurement unit 34 determines whether the received radio wave strength of the currently connected base station is equal to or greater than the third threshold (step S132). If it is determined that the received radio wave strength is equal to or greater than the third threshold (step S132; Yes), the process proceeds to step S134. If it is determined that the received radio wave strength is not equal to or greater than the third threshold (step S132; No), the process proceeds to step S136.

[0062] If the result in step S132 is determined to be Yes, the communication control unit 30 designates the currently connected base station as the second base station and transmits the information of the second base station and the second received signal strength (which is the received signal strength of the second base station) as second received signal strength information to the other wireless communication device 10 set to the first mode via the second communication unit 14 (step S134). Then the process shown in Figure 8 is terminated.

[0063] If the result in step S132 is determined to be No, the base station search unit 32 searches for a new base station (step S136). Then, the process proceeds to step S138.

[0064] The radio wave strength measurement unit 34 determines whether or not there is a base station with a received radio wave strength equal to or greater than the third threshold among the base stations searched in step S136 (step S138). If it is determined that there is a base station with a received radio wave strength equal to or greater than the third threshold (step S138; Yes), the process proceeds to step S140. If it is not determined that there is a base station with a received radio wave strength equal to or greater than the third threshold (step S138; No), the process proceeds to step S144.

[0065] If the answer in step S138 is Yes, the communication control unit 30 switches the base station connected to the wireless communication device 10 from the currently connected base station to a base station found by the base station search unit 32 whose received radio wave strength is equal to or greater than the third threshold (step S140). Here, if there are multiple base stations with a received radio wave strength equal to or greater than the third threshold, the communication control unit 30 switches the connection to the base station that shows the maximum received radio wave strength among the multiple base stations. Then, the process proceeds to step S142.

[0066] The communication control unit 30, using the base station switched in step S140 as the second base station, transmits the information of the second base station and the second received signal strength (which is the received signal strength of the second base station) as second received signal strength information to the other wireless communication device 10 set to the first mode via the second communication unit 14 (step S142). Then, the process shown in Figure 8 is completed.

[0067] If the result in step S138 is determined to be "No", the wireless communication device 10 transitions to an out-of-range state because there are no base stations it can connect to (step S144). When the wireless communication device 10 transitions to an out-of-range state, it becomes unable to transmit received signal strength information from other wireless communication devices. The process shown in Figure 8 then ends. Although not shown, the wireless communication device 10, in an out-of-range state, continues to search for base stations, and if it finds a base station that can receive signals with a received signal strength of 3 or higher, it restarts the process shown in Figure 8.

[0068] As described above, in this embodiment, if a wireless communication device that changes its connection to a base station receives information from another wireless communication device about a base station that can receive signals at a received signal strength of a second threshold or higher, which is higher than the normally used reference threshold, it will change its connection to a new base station with better communication quality without searching for a base station. If information from another wireless communication device about a base station that can receive signals at a received signal strength of a second threshold or higher is not provided, it will maintain its connection to the base station until the received signal strength of the currently connected base station falls below a first threshold, which is lower than the normally used reference threshold. As a result, in this embodiment, when using a wireless communication device, communication quality can be ensured and it is less likely to go out of range.

[0069] Each component of the illustrated device is a functional concept and does not necessarily have to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions. Furthermore, this distribution and integration configuration may be performed dynamically.

[0070] Although embodiments of the present invention have been described above, the present invention is not limited by the content of these embodiments. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the embodiments described above. [Explanation of Symbols]

[0071] 10 Wireless communication devices 12. First Communications Department 14. Second Communications Department 16 Control section 18 Display 20 Audio output section 22 Memory section 24 GNSS receiver 26 Control Unit 30 Communication Control Unit 32 Base station search section 34. Radio wave intensity measurement unit 36 Mode setting section

Claims

1. A first communication unit that communicates with a base station using a first wireless communication method, A second communication unit that communicates with other wireless communication devices using a second wireless communication method, The first communication unit measures the received signal strength value of the radio waves received from the first base station, and A base station search unit controls the first communication unit to search for a new base station to connect to based on the received radio wave strength value, A communication control unit that controls the first communication unit and the second communication unit, A mode setting unit that selectively sets a first mode and a second mode different from the first mode, Equipped with, When the mode setting unit is set to the first mode, The base station search unit searches for a new base station to connect to when the received radio wave strength value falls below a preset first threshold. When the communication control unit receives information from another wireless communication device via the second communication unit that has been received with a received radio wave intensity greater than or equal to a preset second threshold greater than the first threshold, it switches the base station to which it connects from the first base station to the second base station. When the mode setting unit is set to the second mode, The base station search unit searches for a new base station to connect to when the received radio wave intensity value falls below a preset third threshold which is equal to or greater than the second threshold. The communication control unit designates the base station found by the base station search unit as the second base station and transmits information about the second base station via the second communication unit. Wireless communication device.

2. The first communication unit communicates with the base station using the first wireless communication method, The second communication unit communicates with other wireless communication devices using the second wireless communication method, A step of measuring the received signal strength value of the radio waves received from the first base station, The steps include controlling the first communication unit based on the received radio wave strength value to search for a new base station to connect to, The steps include controlling the first communication unit and the second communication unit, A step of selectively setting a first mode and a second mode different from the aforementioned first mode, When set to the first mode, If the received radio wave strength value falls below a preset first threshold, the step is to search for a new base station to connect to, When information from a second base station is received via the second communication unit from another wireless communication device with a received radio wave intensity greater than or equal to a preset second threshold which is greater than the first threshold, A step of switching the base station to connect from the first base station to the second base station, When set to the second mode, If the received radio wave strength value falls below a preset third threshold that is equal to or greater than the second threshold, the step of searching for a new base station to connect to, The step of searching for the base station includes the step of designating the base station found as the second base station and transmitting information about the second base station using the second communication unit, Wireless communication methods, including those mentioned above.

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