WO2013054415A1

WO2013054415A1 - Radio terminal apparatus and wireless communication system

Info

Publication number: WO2013054415A1
Application number: PCT/JP2011/073530
Authority: WO
Inventors: 小林　敬侍
Original assignee: 三菱電機株式会社
Priority date: 2011-10-13
Filing date: 2011-10-13
Publication date: 2013-04-18
Also published as: TWI452915B; WO2013054722A1; TW201316794A

Abstract

This invention is a radio terminal apparatus having a plurality of antennas and forming a mesh network together with a gateway. When a radio terminal apparatus participates in a mesh network, the radio terminal apparatus sequentially uses a plurality of antennas to communicate with adjacent terminals, which are peripheral other radio terminal apparatuses, thereby acquiring, for the case of using each antenna, number-of-hops information indicating a number of hops from a respective adjacent terminal to the gateway and further measuring a communication quality between the local terminal and the respective adjacent terminal, thereby determining, on the basis of the number-of-hops information and the communication quality, an antenna to be used in communication within the mesh network.

Description

Wireless terminal device and wireless communication system

The present invention relates to a wireless terminal device constituting a wireless mesh network system.

As one of the networks of conventional mobile communication devices, wireless terminal devices that cannot communicate directly communicate with each other via a relay device (wireless terminal device that relays communication), thereby enabling mutual communication between a large number of wireless terminal devices. Wireless mesh network technology has been developed to enable it. Such a wireless network is generally referred to as a mesh network, and data communication between wireless terminal devices is performed by relaying a plurality of wireless terminal devices on the way, regardless of base stations, fixed stations, or mobile stations. .

In the network system configured as described above, the data transmitted from the wireless terminal device of the transmission source is relayed (hopped) by the wireless terminal device on the relay path constructed based on the communication quality between the wireless terminal devices, It is delivered to the final destination wireless terminal device. In such a network system, Patent Document 1 describes a technique for further improving communication reliability. Specifically, communication reliability is ensured by selecting the antenna having the best wireless quality at the time of reception as an antenna used for communication with each of a plurality of surrounding wireless terminal devices, since the wireless terminal device has multiple antennas. Techniques for improving the performance are described.

JP 2010-98595 A

As described above, in the technique described in Patent Document 1, an antenna having the best reception quality is selected and used from a plurality of antennas. However, since the reliability of communication as the entire system decreases when the number of times (number of hops) of relaying a signal between the transmission source and the final destination wireless terminal device increases, the adjacent wireless terminal device When an antenna is selected considering only the communication quality between and an antenna, there is a problem that an optimal antenna cannot be selected. In addition, since the relay path is constructed based on the communication quality between the wireless terminal devices in the gateway and each wireless terminal device, each wireless terminal device cannot grasp in advance which wireless terminal device receives the data. Therefore, in a wireless terminal device having a plurality of antennas, if the standby state is selected with the antenna having the best wireless quality for a specific wireless terminal device, the selected antenna is not necessarily the optimal antenna. There is a problem that the reliability of communication is not limited, and the reliability of communication is lowered.

The present invention has been made in view of the above, and in a wireless mesh network, a wireless terminal device that provides highly reliable communication by selecting and using an optimum antenna from a plurality of held antennas, And to obtain a wireless communication system.

In order to solve the above-described problems and achieve the object, the present invention is a wireless terminal device that includes a plurality of antennas and forms a mesh network with a gateway, and the plurality of antennas when joining the mesh network. Hop number information indicating the number of hops from each adjacent terminal to the gateway in each case when using each antenna by communicating with adjacent terminals that are other wireless terminal devices in order using In addition, the communication quality between each adjacent terminal is measured, and an antenna used for communication in the mesh network is determined based on the hop number information and the communication quality.

The wireless terminal device according to the present invention has an effect that more reliable communication can be realized as compared with the case where the antenna to be used is selected considering only the communication quality with other wireless terminals in the vicinity. .

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system including a wireless terminal device according to the present invention. FIG. 2 is a diagram illustrating a configuration example of a gateway. FIG. 3 is a diagram illustrating a configuration example of a wireless processing unit provided in the gateway. FIG. 4 is a diagram illustrating a configuration example of a wireless terminal. FIG. 5 is a sequence diagram illustrating an example when a wireless terminal enters the mesh network. FIG. 6 is a diagram illustrating an example of an operation in which the wireless terminal changes the antenna used. FIG. 7 is a diagram illustrating an example of communication quality information. FIG. 8 is a diagram illustrating an example of information referred to when an antenna used by a wireless terminal is determined. FIG. 9 is a diagram illustrating an example of a procedure in which a wireless terminal holding the information (neighboring terminal information) illustrated in FIG. 8 determines an antenna to be used.

Hereinafter, embodiments of a wireless terminal device and a wireless communication system according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram illustrating a configuration example of a wireless communication system including a wireless terminal device (hereinafter referred to as a wireless terminal) according to the present invention. As illustrated, the wireless communication system includes a management server 1, a gateway 2, and wireless terminals 5A to 5H. In the following, when the matters (device configuration, function, operation, etc.) common to the wireless terminals 5A to 5H are described, the wireless terminals 5A to 5H are collectively referred to as the wireless terminal 5.

The management server 1 and the gateway 2 are arranged to communicate via the wide area network 3, and the management server 1 and the gateway 2 are connected to the wide area network 3 by a communication cable 4 which is an optical cable, for example. The gateway 2 and the wireless terminal 5 are provided with a plurality of antennas, and one antenna is used when signals are transmitted and received. Further, a power meter 6 for measuring the amount of power or the like is connected to the wireless terminal 5 by wire or wirelessly, and the wireless terminal 5 transmits measurement data from the power meter 6 to the management server 1 via the gateway 2. At this time, the wireless terminal 5 that cannot directly communicate with the gateway 2 transmits measurement data to the gateway 2 via the other wireless terminal 5. In the example of FIG. 1, the wireless terminals 5C to 5H are located at a place where the wireless terminals 5C to 5H cannot directly communicate with the gateway 2, and transmit measurement data via other wireless terminals 5.

Details of each device constituting the wireless communication system shown in FIG. 1 will be described.

Although not shown, the management server 1 includes a central control unit that controls the functions of the system, a communication control unit that communicates with the gateway 2 and the wireless terminal 5 via the wide area network 3, and the gateway 2. And a storage device that holds measurement data such as the amount of power acquired via the wireless terminal 5. The management server 1 communicates with the wireless terminal 5 and collects measurement data (such as power consumption) measured by a power meter 6 installed in a consumer or the like.

FIG. 2 is a diagram illustrating a configuration example of the gateway 2. As illustrated, the gateway 2 includes a central control unit 21, a wireless processing unit 22, a communication control unit 23, and an optical input / output unit 24. The central control unit 21 performs data processing with the management server 1 or the wireless terminal 5. The wireless processing unit 22 performs wireless communication control for performing wireless network communication with the wireless terminal 5. The communication control unit 23 performs wired communication control for performing wired network communication with the management server 1. The optical input / output unit 24 performs processing for connecting to the wide area network 3 via the optical cable 4 (conversion processing from an electric signal to an optical signal, conversion processing from an optical signal to an electric signal).

Further, as shown in FIG. 3, the radio processing unit 22 performs radio modulation / demodulation processing with an antenna switch 221 that switches a plurality of antennas 220, and performs communication with the radio terminal 5 using the illustrated communication quality measurement unit 227. A wireless unit 222 having a communication quality measuring unit 227 that measures quality (for example, received electric field strength), a wireless I / F (Interface) unit 223, and a wireless that performs wireless network generation and configuration management of the wireless terminal 5 The network control unit 244, the routing table 225 in which the transfer destination when the signal transmitted from the management server 1 to the wireless terminal 5 is received, and all functions of the wireless processing unit 22 are controlled, and the central control unit 21 and a wireless communication control unit 226 that controls the antenna switch 221 while performing data processing with the device 21. In FIG. 3, two antennas 220 are used, but three or more antennas may be used.

The gateway 2 having such a configuration forms part of the mesh network, and the wireless processing unit 22 communicates with the wireless terminal 5.

In the wireless processing unit 22, the wireless network control unit 224 communicates with the wireless terminal 5 via the antenna 220 and the wireless unit 222. Also, address assignment to all the wireless terminals 5, registration processing of the wireless terminals 5 to the mesh network, and management of the mesh network are performed.

In the gateway 2, when the central control unit 21 receives request data (measurement data transmission request in the power meter 6) from the management server 1 via the optical input / output unit 24 and the communication control unit 23, the wireless processing unit The data is transferred to the wireless network control unit 224 in 22. When the wireless network control unit 224 receives the request data transferred by the central control unit 21, the wireless network control unit 224 analyzes the request data and grasps the destination wireless terminal 5 designated by the management server 1. Then, according to the routing table 225, the request data is transmitted (transferred) via the wireless I / F unit 223, the wireless unit 222, the antenna switch 221 and the antenna 220.

FIG. 4 is a diagram illustrating a configuration example of the wireless terminal 5. As illustrated, the wireless terminal 5 performs a wireless modulation / demodulation process and a plurality of antennas 50 used for wireless communication with the gateway 2 and other wireless terminals 5, an antenna switch 51 for switching the plurality of antennas 50, and communication. Of the data received from the wireless unit 52, the wireless I / F unit 53, and the gateway 2 and other wireless terminals 5 that measure the received electric field strength between the gateway 2 and other wireless terminals 5 by the quality measuring unit 61. A data relay processing unit 54 that transfers data not addressed to itself to another wireless device (gateway 2 or other wireless terminal 5) and data not addressed to itself (data destined for the gateway 2 or other wireless terminal 5) Field strength between the routing table 55 in which the transfer destination is described and a wireless device (gateway 2 or other wireless terminal 5) in the vicinity, and An adjacent terminal information table 56 that holds information on the number of hops from each peripheral wireless terminal 5 to the gateway 2, and a use antenna determination unit that controls the antenna switch 51 to select and determine an antenna to be used from among a plurality of antennas 50. Communication control unit 57 having a function of processing data addressed to itself, a timer unit 58 used for periodically acquiring the information (field strength, hop number information), and power meter 6 Storage unit 59 for storing the measurement data acquired from, and a meter communication processing unit 60 for communicating with the power meter 6. In FIG. 4, two antennas 50 are used, but three or more antennas may be used.

The wireless terminal 5 having such a configuration transmits / receives data to / from the gateway 2 or another wireless terminal 5. When the wireless terminal 5 receives the data, the data relay processing unit 54 checks whether the data is addressed to itself, and if it is addressed to itself, transfers it to the communication control unit 57 and processes it in the communication control unit 57. On the other hand, if it is not addressed to itself, the data relay processing unit 54 determines a relay destination based on the routing table 55 and relays data via the wireless I / F unit 53, the wireless unit 52, the antenna switch 51, and the antenna 50. To do. If there is routing information in the received data, the data relay processing unit 54 performs data relay processing based on the routing information instead of the routing table 55. When transmitting response data to the measurement data transmission request from the management server 1, the response data (measurement data) is transferred to the data relay processing unit 54, and the data relay processing unit 54 relays the relay destination based on the routing table 55. And the response data is transmitted via the wireless I / F unit 53, the wireless unit 52, the antenna switch 51, and the antenna 50.

The communication control unit 57 acquires measurement data from the power meter 6 via the meter communication processing unit 60. The acquired measurement data is stored and stored in the storage unit 59.

The timer unit 58 starts timing when a predetermined condition is satisfied, and then notifies the communication control unit 57 when a predetermined time has elapsed. Upon receiving this notification, the communication control unit 57 transmits a request for information data (details will be described later) to other wireless terminals 5 in the vicinity and receives an information data response as a response signal to the request. Information data included in the information data response is extracted. At this time, in the wireless unit 52, the communication quality measuring unit 61 measures the electric field strength when receiving the information data response. The information data extracted by the communication control unit 57 and the electric field strength measured by the communication quality measurement unit 61 are stored in the adjacent terminal information table 56.

Next, the operation of the wireless communication system according to the present embodiment will be described with reference to FIGS. First, an example of the operation shown in FIG. 5, that is, the operation when the wireless terminal 5G newly enters the mesh network formed by the gateway 2 and the wireless terminals 5A to 5F will be described. It is assumed that the wireless terminal 5G can directly communicate with any of the wireless terminals 5A to 5F, but is newly installed at a position where direct communication with the gateway 2 is impossible. The wireless terminal 5G includes a plurality of antennas (here, described as two antennas # 1 and # 2), and selects one antenna to be used from among the plurality of antennas when entering the mesh network. And

When the wireless terminal 5G is newly installed (step S11), the wireless terminal 5G first selects another antenna 5 (hereinafter referred to as an adjacent terminal) capable of direct communication in order to select an antenna to be used after entering the mesh network. The number of hops to the gateway 2 (upper limit value) and a threshold value (lower limit value) of the electric field strength between adjacent terminals are set as conditions for acquiring information data from (referred to as the above). In the case of a new installation, it is desirable to acquire a lot of information data and select an antenna. Therefore, for example, the number of hops to the gateway = the maximum number of hops allowed in the wireless communication system, and the field strength threshold = the minimum received field strength. In the example shown in FIG. 5, the wireless terminals 5A to 5F are adjacent terminals.

Next, the wireless terminal 5G selects the antenna # 1 that is one of the plurality of antennas (step S13), and uses the antenna # 1 to select the antenna selection condition (gateway 2) set in step S12. An information data request in which the number of hops up to and the electric field strength threshold between adjacent terminals are inserted is broadcast (step S14).

The adjacent terminals (

wireless terminals

5A, 5B, 5C, 5D, 5E, and 5F) that have received the information data request receive the antenna selection conditions in the information data request (the number of hops to the gateway 2 and the electric field strength threshold between the adjacent terminals). ) To get. When receiving the information data request, the electric field strength is measured and the measurement result is held. The received information data request is not transferred to another wireless terminal 5.

Also, the wireless terminals 5A to 5F that have received the information data request indicate the number of hops to the gateway 2 and the electric field strength (indicating the communication quality with the wireless terminal 5G) measured when the information data request is received. If the antenna selection condition is satisfied as compared with the acquired antenna selection condition, an information data response including information on the number of hops to the gateway 2 as information data is returned (step S15). That is, when both “the number of hops to the gateway 2 ≦ the number of hops indicated by the antenna selection condition” and “the electric field intensity measured when the information data request is received ≧ the electric field intensity threshold indicated by the antenna selection condition” are satisfied, Will be returned. In this case, it is possible to prevent the wireless traffic from increasing unnecessarily and to suppress power consumption. The wireless terminal 5G measures the electric field strength when receiving the information data response, and holds the measurement result.

The wireless terminal 5G receives the information data (up to the gateway 2) included in the information data response received from each adjacent terminal (wireless terminals 5A to 5F) after a predetermined time has elapsed since the information data request was transmitted in step S14. Information on the number of hops) and the electric field strength measured when the information data response is received are stored as information on antenna # 1 (antenna information).

Next, the wireless terminal 5G selects the antenna # 2 (step S16), and uses the antenna # 2 to transmit the information data in which the antenna selection condition set in the step S12 is inserted in the same manner as in the step S14. The request is transmitted by broadcast (step S17).

Each adjacent terminal (wireless terminals 5A to 5F) that has received the information data request receives the number of hops to the gateway 2 and the information data request in step S17, as in the case of receiving the information data request in step S14. The field strength measured sometimes is compared with the antenna selection condition acquired from the information data request, and if the antenna selection condition is satisfied, an information data response including information on the number of hops to the gateway 2 is returned (step). S18).

The wireless terminal 5G transmits the information data request in step S17, and after a predetermined time has elapsed, the information on the number of hops to the gateway 2 included in the information data response received from each adjacent terminal, and the information data response The electric field strength measured at the time of reception is held as information on antenna # 2. Since the number of hops from a certain adjacent terminal to the gateway 2 is constant regardless of the antenna selected by the wireless terminal 5G, the hop number information is not extracted when the information data response is received with the antenna # 2 selected. Thus, the processing load may be reduced.

When the wireless terminal 5G has three or more antennas, after executing step S18, another antenna is selected and the same processing (the same processing as steps S14 and S15) is repeated.

The wireless terminal 5G selects (uses) each antenna provided and transmits an information data request and receives an information data response. When the collection of antenna information is completed, based on the collected antenna information, The antenna to be used is determined (step S19). Details of the processing in step S19 will be described separately.

When the wireless terminal 5G determines the antenna to be used, the wireless terminal 5G uses the determined antenna to transmit a network entry request in which the final destination is set to the gateway 2 to the gateway 2 directly or via an adjacent terminal (steps S20 and S21). In the example of FIG. 5, the network entry request transmitted from the wireless terminal 5G reaches the gateway 2 via the wireless terminal 5B.

The gateway 2 that has received the network entry request executes a process for causing the requesting wireless terminal 5G to enter the mesh network, and then returns a network entry response (steps S22 and S23).

When the wireless terminal 5G receives the network entry response transmitted from the gateway 2 directly or via an adjacent terminal, the network entry process is completed.

Through the above procedure, the wireless terminal 5G determines the antenna to be used when entering the mesh network.

Next, a wireless terminal that has already entered the mesh network (referred to as wireless terminal 5G) periodically checks the necessity of changing the antenna to be used, and when it is determined to be necessary, the operation of changing the antenna is described with reference to FIG. I will explain. Although this operation is not essential, the state (communication quality) of wireless communication is unstable compared to wired communication, and another wireless terminal 5 newly enters or leaves the mesh network. This is desirable because the relay route may change.

When the entry into the mesh network is completed, the wireless terminal 5G performs setting (initialization) of a timer value that periodically activates an antenna change necessity determination (antenna change necessity determination) (step S31). For example, when the antenna change necessity determination is performed once per hour, the timer value is set to 1 hour. The timer value is set by the communication control unit 57, for example. Thereafter, it is monitored whether or not the time set in step S31 has elapsed (step S32), and monitoring is continued until the set time has elapsed (step S32: No).

When the time set in step S31 has elapsed (step S32: Yes), the wireless terminal 5G receives information from the adjacent terminal in order to collect information data to be used in determining whether the antenna to be used needs to be changed. As conditions for acquiring information data (antenna selection conditions), the number of hops to gateway 2 (upper limit value) and a threshold value (lower limit value) of electric field strength between adjacent terminals are set (step S33). This step S33 is the same process as step S12 described above. In the case of periodic processing after entering the network, in order to avoid interference (interference with other communications), the condition that the adjacent terminal responds is restricted. For example, the number of hops to the gateway 2 = 3, electric field strength The threshold value is set to 90 dBμV. Note that only one of the number of hops and the electric field strength threshold may be set.

Next, the wireless terminal 5G selects the antenna # 1 that is one of the plurality of antennas (step S34), and uses the antenna # 1 to select the antenna selection condition (gateway 2) set in step S33. The information data request in which the number of hops and the electric field strength threshold are inserted is transmitted by broadcast (step S35). This step S34 is the same process as step S14 described above.

The wireless terminal 5G confirms whether or not the information data response has been received from the adjacent terminal within a certain time, and when receiving the information data response, performs measurement of the electric field strength and holds the measured value, and the information data response indicates The number of hops (the number of hops to gateway 2) is held (steps S36, S37, S38). If the predetermined time has not elapsed since the information data request was transmitted in step S35 (step S39: No), steps S36 to S38 are repeated. On the other hand, if the predetermined time has elapsed (step S39: Yes), whether or not the selection of all antennas has been completed, that is, whether or not the above steps S35 to S39 have been executed using all the provided antennas. Is confirmed (step S40). If selection of all antennas has not been completed (step S40: No), the antenna is switched to an unselected antenna (step S41), and the above steps S35 to S39 are executed again. When the selection of all antennas is completed (step S40: Yes), the antenna to be used is determined based on the antenna information that is information obtained by repeatedly executing the processes of steps S35 to S38 described above (step S42). ). The method for determining the antenna used is the same as the method for determining the antenna used in the network entry operation described above.

After determining the antenna to be used, the wireless terminal 5G updates the number of hops from itself to the gateway 2 (step S43). When step S43 ends, the process returns to step S31 described above to set the timer value. Thereafter, the above-described operation is continued.

Subsequently, based on the antenna information collected by the wireless terminal 5 transmitting the information data request and receiving the information data response (the number of hops from the adjacent terminal to the gateway 2 and the electric field strength when the information data response is received). An example of the operation for determining the antenna to be used (the above-described operations in steps S19 and S42) will be described with reference to FIGS.

FIG. 7 is a diagram illustrating an example of communication quality information indicating the electric field strength between the wireless terminal 5 and the adjacent terminal. In the illustrated example, the quality rank corresponding to the electric field strength is used as the communication quality information. “1” is the highest quality.

FIG. 8 is a diagram illustrating information that is referred to when the wireless terminal 5 determines the antenna to be used. As an example, information that the wireless terminal 5G refers to (holds) is illustrated. This information is obtained when the wireless terminal 5G receives an information data response from other wireless terminals (wireless terminals 5A to 5H). Further, it is held as an adjacent terminal information table 56.

In FIG. 8, “terminal number” is information (identifier) uniquely indicating each surrounding wireless terminal 5. In FIG. 8, for convenience of explanation, a wireless terminal corresponding to the terminal number is shown. "The number of hops to the gateway acquired from another wireless terminal" is information (hop number information) indicating the number of hops from another wireless terminal (source of information data response) corresponding to the terminal number to the gateway 2, Extracted from the received information data response. “Quality rank with wireless terminals in the vicinity” is information indicating the electric field strength (communication quality) at the time of receiving an information data response at each of the provided antennas (antennas # 1 and # 2 in the illustrated example). In order to reduce the amount of information, the information obtained by converting the electric field strength into the quality rank based on the table shown in FIG. 7 (correspondence table of electric field strength and quality rank) is defined as “quality rank with wireless terminals in the vicinity”. . In the example of FIG. 8, it is assumed that communication between the wireless terminal 5G and the wireless terminals 5A and 5H is unstable, and the wireless terminal 5G cannot receive the information data response from the wireless terminals 5A and 5H. Therefore, the information corresponding to the wireless terminals 5A and 5H (the number of hops to the gateway acquired from other wireless terminals, the quality rank with the surrounding wireless terminals) is “no response”. The “multiplier value of the number of hops and the quality rank” is a multiplication result of “the number of hops to the gateway acquired from another wireless terminal” and “quality rank with the wireless terminals in the vicinity”.

FIG. 9 is a diagram illustrating an example of a procedure in which the wireless terminal 5G holding the information (neighboring terminal information) illustrated in FIG. 8 determines the antenna to be used, and is based on the antenna selection condition illustrated in FIG. The operation when determining the antenna to be used is shown. The antenna selection condition includes condition 1 to condition 3, and in condition 1, “the number of hops to gateway 2” is set to “3 or less”. In condition 2, “quality rank” is set to “5 or more”. In condition 3, “multiplied value of the number of hops and the quality rank” is set to “8 or less”.

The wireless terminal 5G first identifies the wireless terminal 5 that satisfies the condition 1 in the operation of determining the antenna to be used. In the example illustrated in FIG. 9, the

wireless terminals

5B, 5C, 5D, and 5E are specified as terminals that satisfy the condition 1. Next, the wireless terminal 5 satisfying the condition 2 is specified for each antenna. In the example shown in FIG. 9,

wireless terminals

5B, 5C, 5D, 5E, and 5F are specified as terminals that satisfy condition 2 when antenna # 1 is used, and terminals that satisfy condition 2 when antenna # 2 is used.

Wireless terminals

5B, 5C, 5D, 5E, and 5F are identified. Furthermore, the wireless terminal 5 satisfying the condition 3 is specified for each antenna. In the example illustrated in FIG. 9, the

wireless terminals

5B, 5C, 5D, and 5F are specified as terminals that satisfy the condition 3 when the antenna # 1 is used, and the terminals that satisfy the condition 3 are wireless when the antenna # 2 is used.

Terminals

5B, 5C, 5D, and 5F are specified.

When the specification of the terminals satisfying the

conditions

1, 2 and 3 is completed, the wireless terminal 5G next extracts the wireless terminals 5 satisfying the conditions 1 to 3 for each antenna (in the example of FIG. 9, antenna # The

wireless terminals

5B, 5C, and 5D are extracted both when using 1 and when using antenna # 2. Then, the average value of the “multiplied value of the number of hops and the quality rank” of the extracted wireless terminal 5 is calculated for each antenna. That is, the average value of the “multiplied value of the number of hops and the quality rank” of the wireless terminal 5 that satisfies the conditions 1 to 3 when the antenna # 1 is used, and the “hop” of the wireless terminal 5 that satisfies the conditions 1 to 3 when the antenna # 2 is used The average value of “the product of the number and the quality rank” is calculated. Based on the result thus calculated, the antenna to be used is determined. Specifically, an antenna having a smaller calculated average value is determined as a use antenna. In the illustrated example, the average value when antenna # 1 is used = 5 and the average value when antenna # 2 is used = 6.6, so antenna # 1 is determined as the antenna to be used.

The wireless terminal 5 updates the information on the number of hops from itself to the gateway 2 after executing the process of determining the antenna to be used. Specifically, when the determined antenna is used, the value obtained by adding 1 to the number of hops from the wireless terminal 5 to the gateway 2 that minimizes the “multiplied value of the number of hops and the quality rank” from itself to the gateway 2 Set as the number of hops. In the illustrated example, the wireless terminal 5 having the smallest “multiplier value of the number of hops and the quality rank” when the determined antenna # 1 is used is the wireless terminal 5B. Since the number of hops from the wireless terminal 5B to the gateway 2 is 1, the number of hops from itself to the gateway 2 is set (updated) to 2.

As described above, when the wireless terminal 5 enters the mesh network (at the time of start-up) and periodically in the already-entered state, the wireless terminal 5 sends an information data request to the adjacent terminal and the number of hops to the gateway 2 And communication quality (electric field strength) information with other wireless terminals are collected, and the antenna to be used is determined (or redetermined).

The operation when determining the antenna to be used has been described. However, when the wireless terminal 5 receives an information data request from an adjacent terminal (a wireless terminal trying to determine the antenna to be used), the number of hops to the gateway 2 An information data response in which is inserted is returned to the wireless terminal 5 that is the transmission source.

As described above, the wireless communication system according to the present embodiment includes at least one wireless terminal fixedly installed in the vicinity of the power meter and at least one wireless terminal that relays data measured by the power meter wirelessly. The wireless terminal has multiple antennas, and each antenna is selected and used sequentially at startup (when entering the mesh network) and when it has already entered the mesh network. Get the number of hops to the gateway held by another wireless terminal, and measure the communication quality (electric field strength) with other wireless terminals, and use it based on the communication quality and the number of hops The antenna was decided. In this way, considering the number of hops to the gateway that has a large impact on communication quality and the electric field strength between adjacent wireless terminals, communication is performed using the antenna that provides the best communication quality among multiple antennas. It becomes possible to do. As a result, more reliable communication can be realized as compared with a conventional system that selects an antenna to be used in consideration only of communication quality with other wireless terminals in the vicinity.

In addition, in response to an information data request for requesting information on the number of hops to the gateway from other wireless terminals, the wireless terminal is an antenna that indicates a threshold for the number of hops to the gateway and the reception quality (field strength) of the information data request. When a selection condition is set and transmitted and an information data request is received, an information data response that is a response to the request is returned only when the set antenna selection condition is satisfied. As a result, the wireless terminal that has received the information data request has the number of hops to the gateway equal to or less than the number of hops specified in the antenna selection condition, and the electric field strength when the information data request is received is specified in the antenna selection condition. Since the information data response is transmitted when the electric field strength threshold is greater than or equal to the threshold value, the interference between the communication related to the acquisition of information data for selecting an antenna and other communication can be suppressed.

As described above, the wireless terminal device according to the present invention is useful as a wireless terminal device that performs communication by selecting one antenna from a plurality of antennas, and is particularly suitable for a wireless communication terminal that forms a mesh network. ing.

1 management server 2 gateway 3 wide area network 4 communication cable (optical cable)
5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H Wireless terminal device 6 Power meter 21 Central control unit 22 Wireless processing unit 23, 57 Communication control unit 24 Optical input /

output unit

50, 220 Antenna 51, 221 Antenna switch 52 , 222

Wireless unit

53, 223 Wireless I / F unit 54 Data relay processing unit 55, 225 Routing table 56 Adjacent terminal information table 58 Timer unit 59 Storage unit 60 Meter communication processing unit 61, 227 Communication quality measurement unit 224 Wireless network control unit 226 Wireless communication control unit

Claims

A wireless terminal device comprising a plurality of antennas and forming a mesh network with a gateway,
When participating in the mesh network, by using the plurality of antennas in order and communicating with neighboring terminals that are other wireless terminal devices in the vicinity, each antenna is used from each neighboring terminal when using each antenna. Obtains hop count information indicating the number of hops to the gateway and measures the communication quality with each adjacent terminal, and determines the antenna to be used for communication within the mesh network based on the hop count information and communication quality A wireless terminal device.
An antenna switch for switching the antenna to be used;
When using each antenna, for each, an electric field strength measuring unit that measures electric field strength as the communication quality,
Obtaining the hop number information from each adjacent terminal, determining an antenna to be used for communication in the mesh network based on the hop number information and the electric field strength, and selecting an antenna corresponding to the determined result as the antenna switch Use antenna determination unit to be selected,
The wireless terminal device according to claim 1, further comprising:
The radio terminal apparatus according to claim 2, wherein the electric field strength measurement unit measures the electric field strength of a signal received from an adjacent terminal through communication for the use antenna determination unit to acquire the hop number information. .
In the state that has already entered the mesh network,
The used antenna determination unit periodically acquires the hop number information from each adjacent terminal, and acquires the acquired hop number information and the electric field measured by the electric field strength measurement unit when acquiring the hop number information. 4. The wireless terminal device according to claim 3, wherein an antenna used for communication in the mesh network is re-determined based on the strength.
In the communication for acquiring the hop number information, at least one of the lower limit value of communication quality and the upper limit value of the hop number is notified to the adjacent terminal as a response condition, and the hop number information is transmitted only from the terminal satisfying the response condition. The wireless terminal device according to claim 1, wherein:
In the state that has already entered the mesh network,
When receiving an inquiry about the number of hops to the gateway while being notified of at least one of the lower limit value of communication quality and the upper limit value of the number of hops as a response condition from an adjacent terminal, if the response condition is satisfied, The wireless terminal apparatus according to claim 1, wherein information on the number of hops is returned.
A wireless terminal device according to any one of claims 1 to 6;
A gateway accommodating the wireless terminal device;
A wireless communication system comprising:
A management server that collects power measurement data from a power meter installed in a consumer;
The wireless terminal device has a function of acquiring power measurement data by connecting a power meter, and transmits the acquired power measurement data to the management server via the gateway.
The wireless communication system according to claim 7.