Mobile communication device, mobile gateway device, control circuit, and program storage medium

Abstract

A mobile communication device (104) selects route construction requests, which have been received from other mobile communication devices and mobile gateway devices, by the number of hops and delay of wireless multi-hop communication and an evaluation value related to the communication quality.

Description

Mobile communication device, mobile gateway device, control circuit and program storage medium

[0001] The present disclosure relates to a mobile communication device, a mobile gateway device, a control circuit, and a program storage medium for a wireless multi-hop network.

[0002] In order to quickly grasp the damage situation during a disaster, it is necessary to acquire information from any location using mobile communication devices such as drones. One method for acquiring this information is to configure a wireless multi-hop network by placing many mobile communication devices around a gateway device. Considering the transmission delay caused by multi-hop communication, the installation locations of the mobile communication devices are limited to the vicinity of the gateway device.

[0003] Patent Literature 1 discloses a method for determining a communication path in a wireless multi-hop network that is configured with a large number of wireless communication devices and several gateway devices. Specifically, Patent Literature 1 discloses a technique for comparing the delay when only wireless multi-hop communication is performed with the delay when optical communication between gateway devices and wireless multi-hop communication are performed, and selecting a path with the least delay.

[0004] JP 2009-188647 A

[0005] In the event of a disaster, mobile communication devices need to collect information with low latency from any location. However, in the conventional technology described above, the route with the shortest latency is selected on the assumption that the gateway device is fixed, so the latency increases the further the wireless communication device is from the gateway device. While the problem of increased latency can be solved by deploying multiple gateway devices throughout the network, public network communications are often used for the interface between the gateway device and the server, which increases operational costs.

[0006] The present disclosure has been made in view of the above, and aims to provide a mobile communication device that can realize low-latency wireless multi-hop communication at a minimum cost in any location.

[0007] In order to solve the above-mentioned problems and achieve the objectives, a mobile communication device according to the present disclosure selects route construction requests received from other mobile communication devices and mobile gateway devices based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

[0008] The mobile communication device according to the present disclosure has an effect of being able to realize low-latency wireless multi-hop communication at a minimum cost in any location.

[0009] FIG. 1 is a diagram showing the configuration of a wireless multi-hop network according to the first embodiment. FIG. 2 is a block diagram showing the configuration of a mobile gateway device according to the first embodiment. FIG. 1 is a diagram showing the hardware configuration of a mobile gateway device according to the first embodiment. FIG. 2 is a block diagram showing the configuration of a mobile communication device according to the first embodiment. FIG. 1 is a diagram showing the hardware configuration of a mobile communication device according to the first embodiment. FIG. 2 is a diagram showing the hardware configuration of a mobile communication device according to the first embodiment.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mobile communication device, a mobile gateway device, a control circuit, and a program storage medium according to embodiments will be described in detail below with reference to the accompanying drawings.

[0011] In the following, multi-hop may be referred to as MH. Communication between the server device and the mobile gateway device, communication between the mobile gateway device and the mobile communication device, and communication between two mobile communication devices are all wireless communications. Communication between the server device and the mobile gateway device, communication between the mobile gateway device and the mobile communication device, and communication between two mobile communication devices may each be performed by other communication means instead of wireless communication. An example of other communication means is wired communication. In the embodiment, AODV (Ad hoc On-Demand Distance Vector), which is compatible with mobile communications, is assumed as the routing protocol in the wireless multi-hop network. Another routing protocol may be adopted instead of AODV.

[0012] Embodiment 1. Fig. 1 is a diagram showing the configuration of a wireless multi-hop network 101 according to embodiment 1. The wireless multi-hop network 101 has a server device 102, a mobile gateway device, and a mobile communication device. Fig. 1 shows mobile gateway device 103a and mobile gateway device 103b as examples of the mobile gateway device, and mobile communication device 104a, mobile communication device 104b, and mobile communication device 104c as examples of the mobile communication device.

[0013] Hereinafter, the mobile gateway device may be referred to as "mobile gateway device 103." Mobile gateway device 103 is a device that collectively refers to mobile gateway device 103a and mobile gateway device 103b. Hereinafter, the mobile communication device may be referred to as "mobile communication device 104." Mobile communication device 104 is a device that collectively refers to mobile communication device 104a, mobile communication device 104b, and mobile communication device 104c. In FIG. 1, server communication indicating communication between server device 102 and each of mobile gateway device 103a and mobile gateway device 103b is shown with a solid line. In FIG. 1, MH communication indicating communication between mobile gateway device 103a and mobile communication device 104b, communication between mobile gateway device 103b and mobile communication device 104a, and communication between mobile communication device 104b and mobile communication device 104c is shown with a dashed line.

[0014] The mobile gateway device 103 may act as a mobile gateway device or as a mobile communication device. Hereinafter, the mobile gateway device 103 acting as a mobile gateway device may be described as mobile gateway device 103 (ON), and the mobile gateway device 103 acting as a mobile communication device may be described as mobile gateway device 103 (OFF).

[0015] Any mobile communication device 104 measures sensor data related to a disaster and transmits the data acquired by the measurement via wireless communication to mobile gateway device 103 (ON) acting as a mobile gateway device. Mobile gateway device 103 (ON) transmits data aggregated from multiple mobile communication devices 104 and mobile gateway device 103 (OFF) acting as a mobile communication device, as well as data acquired by itself, to server device 102 via wireless communication. Mobile gateway device 103 (OFF) performs the same operation as mobile communication device 104.

[0016] When mobile gateway device 103 (ON) and any mobile communication device 104 cannot wirelessly communicate with each other, a mobile communication device 104 or mobile gateway device 103 (OFF) located on the communication path relays data transmission between mobile gateway device 103 (ON) and the given mobile communication device 104. The path at this time may be determined by mobile gateway device 103 (ON), or may be determined autonomously by multiple mobile communication devices 104. Mobile communication devices 104 include mobile gateway device 103 (OFF). Server device 102 accumulates and manages data received from multiple mobile gateway devices 103 (ON).

[0017] The following describes the configuration of mobile gateway apparatus 103. Fig. 2 is a block diagram showing the configuration of mobile gateway apparatus 103 according to embodiment 1. Mobile gateway apparatus 103 has an MH communication unit 201, an MH communication management unit 202, an MH route evaluation unit 203, a gateway control unit 204, a sensor unit 205, a server communication management unit 206, and a server communication unit 207.

[0018] The MH communication unit 201 converts information acquired from the mobile communication device 104 or another mobile gateway device 103 into information in a format that can be read by the MH communication management unit 202, and transmits the information to the MH communication management unit 202. The MH communication unit 201 converts information acquired from the MH communication management unit 202 into information in a format that can be read by the mobile communication device 104 or another mobile gateway device 103, and transmits the information to the mobile communication device 104 or another mobile gateway device 103.

[0019] The MH communication management unit 202 converts the information acquired from the MH communication unit 201 into information in a format that can be read by the MH route evaluation unit 203 or the gateway control unit 204, and transmits the information to the MH route evaluation unit 203 or the gateway control unit 204. The MH communication management unit 202 determines the destination of the MH communication based on the information acquired from the MH route evaluation unit 203 and the gateway control unit 204, converts the destination into a destination in a format that can be read by the MH communication unit 201, and specifies the destination to the MH communication unit 201. The MH communication management unit 202 converts the information acquired from the sensor unit 205 into information in a format that can be read by the MH communication unit 201, and transmits the information to the MH communication unit 201.

[0020] The MH route evaluation unit 203 converts the route evaluation information extracted from the information obtained from the MH communication management unit 202 into route evaluation information in a format that can be read by the MH communication management unit 202 or the gateway control unit 204, and transmits it to the MH communication management unit 202 or the gateway control unit 204.

[0021] The gateway control unit 204 determines whether the mobile gateway device 103 including the gateway control unit 204 should operate as a gateway based on the route evaluation information acquired from the MH route evaluation unit 203, and if it determines that the mobile gateway device 103 including the gateway control unit 204 should operate as a gateway, it controls the MH communication management unit 202 and the server communication management unit 206.

[0022] The sensor unit 205 converts the information it measures into information in a format that can be read by the MH communication management unit 202 or the server communication management unit 206 , and transmits it to the MH communication management unit 202 or the server communication management unit 206 .

[0023] The server communication management unit 206 converts the information acquired from the MH communication management unit 202 via the gateway control unit 204 and the information acquired from the sensor unit 205 into information in a format that can be read by the server communication unit 207, and transmits the information to the server communication unit 207. The server communication management unit 206 converts the information acquired from the server communication unit 207 into information in a format that can be read by the gateway control unit 204, and transmits the information to the gateway control unit 204.

[0024] The server communication unit 207 converts the information acquired from the server communication management unit 206 into information in a format that can be read by the server device 102, and transmits the information to the server device 102. The server communication unit 207 converts the information acquired from the server device 102 into information in a format that can be read by the server communication management unit 206, and transmits the information to the server communication management unit 206.

[0025] 3 is a first diagram showing a hardware configuration of mobile gateway device 103 according to embodiment 1. Mobile gateway device 103 has an antenna 301 for MH communication, an antenna 302 for server communication, an MH communication interface 303, a server communication interface 304, a processor 305, a memory 306, a storage 307, a power supply circuit 308, and a battery 309.

[0026] The processor 305, memory 306, and storage 307 process data frames. Each of the memory 306 and storage 307 is realized by, for example, a semiconductor memory. The power supply circuit 308 and battery 309 supply power to the MH communication interface 303, the server communication interface 304, the processor 305, memory 306, and storage 307.

[0027] Fig. 4 is a second diagram showing the hardware configuration of mobile gateway device 103 according to embodiment 1. In Fig. 4, processor 305, memory 306, and storage 307 in Fig. 3 are replaced with dedicated circuit 405. Dedicated circuit 405 is a processing circuit that performs processing equivalent to the processing performed by processor 305, memory 306, and storage 307. Mobile gateway device 103 may be realized by the hardware configuration shown in Fig. 3 or the hardware configuration shown in Fig. 4.

[0028] Next, we will explain the configuration of mobile communication device 104. Fig. 5 is a block diagram showing the configuration of mobile communication device 104 according to embodiment 1. Mobile communication device 104 has MH communication section 501, MH communication management section 502, MH route evaluation section 503, and sensor section 504.

[0029] The MH communication unit 501 converts information acquired from the mobile gateway device 103 or another mobile communication device 104 into information in a format that can be read by the MH communication management unit 502, and transmits the information to the MH communication management unit 502. The MH communication unit 501 converts information acquired from the MH communication management unit 502 into information in a format that can be read by the mobile gateway device 103 or another mobile communication device 104, and transmits the information to the mobile gateway device 103 or another mobile communication device 104.

[0030] The MH communication management unit 502 converts the information acquired from the MH communication unit 501 into information in a format that can be read by the MH route evaluation unit 503, and transmits the information to the MH route evaluation unit 503. The MH communication management unit 502 determines the destination of the MH communication based on the information acquired from the MH route evaluation unit 503, converts the destination into a destination in a format that can be read by the MH communication unit 501, and specifies the destination to the MH communication unit 501. The MH communication management unit 502 converts the information acquired from the sensor unit 504 into information in a format that can be read by the MH communication unit 501, and transmits the information to the MH communication unit 501.

[0031] The MH route evaluation unit 503 converts the route evaluation information extracted from the information acquired from the MH communication management unit 502 into route evaluation information in a format that can be read by the MH communication management unit 502 and transmits it to the MH communication management unit 502.

[0032] The sensor unit 504 converts the information it has measured into information in a format that can be read by the MH communication management unit 502 and transmits it to the MH communication management unit 502 .

[0033] 6 is a first diagram showing the hardware configuration of the mobile communication device 104 according to embodiment 1. The mobile communication device 104 has an antenna 601 for MH communication, an MH communication interface 602, a processor 603, a memory 604, a storage 605, a power supply circuit 606, and a battery 607.

[0034] The processor 603, memory 604, and storage 605 process data frames. Each of the memory 604 and storage 605 is realized by, for example, a semiconductor memory. The power supply circuit 606 and battery 607 supply power to the MH communication interface 602, processor 603, memory 604, and storage 605.

[0035] Fig. 7 is a second diagram showing the hardware configuration of mobile communication device 104 according to embodiment 1. In Fig. 7, processor 603, memory 604, and storage 605 in Fig. 6 are replaced with a dedicated circuit 703. Dedicated circuit 703 is a processing circuit that performs processing equivalent to the processing performed by processor 603, memory 604, and storage 605. Mobile communication device 104 may be realized by the hardware configuration shown in Fig. 6 or by the hardware configuration shown in Fig. 7.

[0036] Next, the route determination operation performed by the mobile gateway apparatus 103 will be described with reference to the flowchart in FIG. 8 . FIG. 8 is a flowchart showing the procedure of the route determination operation performed by the mobile gateway apparatus 103 according to the first embodiment. The mobile gateway apparatus 103 receives an RREQ (Route Request) from another mobile gateway apparatus 103 or the mobile communication apparatus 104 (S801). The mobile gateway apparatus 103 determines whether the evaluation value of the RREQ stored in the MH route evaluation unit 203 is within the validity period (S802). In FIG. 8 , the operation of step S802 is indicated by the phrase "Is the evaluation value of the previously stored RREQ within the validity period?" If the mobile gateway apparatus 103 determines that the evaluation value of the RREQ stored in the MH route evaluation unit 203 is within the validity period (Yes in S802), it performs the operation of step S803. If the mobile gateway apparatus 103 determines that the evaluation value of the RREQ stored in the MH route evaluation unit 203 is outside the validity period (No in S802), it performs the operation of step S804. Hereinafter, the evaluation value may be referred to as a "route evaluation value."

[0037] In step S803, the mobile gateway device 103 determines whether the evaluation value of the newly received RREQ is greater than the evaluation value of the RREQ stored in the MH route evaluation unit 203. In Fig. 8, the operation of step S803 is indicated by the phrase "Is it greater than the evaluation value of the RREQ previously stored?" If the mobile gateway device 103 determines that the evaluation value of the newly received RREQ is greater than the evaluation value of the RREQ stored in the MH route evaluation unit 203 (Yes in S803), it performs the operation of step S804, and if it determines that the evaluation value of the newly received RREQ is equal to or less than the evaluation value of the RREQ stored in the MH route evaluation unit 203 (No in S803), it performs the operation of step S807.

[0038] In step S804, the mobile gateway device 103 stores the evaluation value of the newly received RREQ in the MH route evaluation unit 203 and transfers the RREQ from the MH communication unit 201 to another mobile gateway device 103 or the mobile communication device 104. Thereafter, the mobile gateway device 103 transfers the route evaluation value from the MH route evaluation unit 203 to the gateway control unit 204 (S805). Next, the mobile gateway device 103 performs the gateway ON / OFF determination process shown in FIG. 9 in the gateway control unit 204 (S806). The mobile gateway device 103 determines whether the current time is within the system operation hours (S807). If the mobile gateway device 103 determines that the current time is within the system operation hours (Yes in S807), it performs the operation of step S801. If the mobile gateway device 103 determines that the current time is outside the system operation hours (No in S807), it terminates the operation. It is assumed that the server device 102, mobile gateway device 103, and mobile communication device 104 are time-synchronized with the server device 102 as the master. When the mobile communication device 104 and mobile gateway device 103 are time-synchronized, this is expressed as being within the system operation time. The system refers to the entire multi-hop network, including applications.

[0039] The gateway ON / OFF determination process of step S806 in Fig. 8 will be described with reference to the flowchart of Fig. 9. Fig. 9 is a flowchart showing the procedure of the gateway ON / OFF determination process performed by the mobile gateway apparatus 103 according to embodiment 1. The mobile gateway apparatus 103 determines in the gateway control unit 204 whether the route evaluation value acquired from the MH route evaluation unit 203 is equal to or greater than a threshold value (S901). The threshold value is a predetermined value. If the mobile gateway apparatus 103 determines that the route evaluation value acquired from the MH route evaluation unit 203 is equal to or greater than the threshold value (Yes in S901), it performs the operation of step S902, and if it determines that the route evaluation value acquired from the MH route evaluation unit 203 is less than the threshold value (No in S901), it performs the operation of step S905.

[0040] In step S902, the mobile gateway device 103 increments the gateway OFF count by 1 in the gateway control unit 204. The gateway OFF count is the number of times that the MH route evaluation unit 203 evaluates that a predetermined communication quality is not met within a certain period of time. Thereafter, the mobile gateway device 103 determines whether the gateway OFF count has reached an upper limit (S903). The upper limit is a predetermined value. If the mobile gateway device 103 determines that the gateway OFF count has reached the upper limit (Yes in S903), it performs the operation of step S904. If the mobile gateway device 103 determines that the gateway OFF count has not reached the upper limit (No in S903), it ends the gateway ON / OFF determination process. In step S904, the mobile gateway device 103 resets the gateway OFF count and turns off the gateway function. After performing the operation of step S904, the mobile gateway device 103 ends the gateway ON / OFF determination process.

[0041] In step S905, the mobile gateway device 103 increments the gateway ON count by 1 in the gateway control unit 204. The gateway ON count is the number of times that a predetermined communication quality is satisfied within a certain period of time as evaluated by the MH route evaluation unit 203. Thereafter, the mobile gateway device 103 determines whether the gateway ON count has reached an upper limit (S906). This upper limit is a predetermined value. If the mobile gateway device 103 determines that the gateway ON count has reached the upper limit (Yes in S906), it performs the operation of step S907. If the mobile gateway device 103 determines that the gateway ON count has not reached the upper limit (No in S906), it ends the gateway ON / OFF determination process. In step S907, the mobile gateway device 103 resets the gateway ON count and turns on the gateway function. After performing the operation of step S907, the mobile gateway device 103 ends the gateway ON / OFF determination process.

[0042] The reason for switching from the ON and OFF counts that have reached their upper limit is to stagger the timing of switching from surrounding mobile gateway devices 103. The mobile gateway device 103 measures the communication quality of multi-hop communication for a certain period of time after starting gateway ON / OFF determination. The mobile gateway device 103 increments the gateway ON count by 1 if the measured communication quality satisfies a predetermined communication quality, and increments the gateway OFF count by 1 if the measured communication quality does not satisfy the predetermined communication quality. The gateway ON count and gateway OFF count each have an upper limit, and when either the gateway ON count or the gateway OFF count reaches its upper limit, the mobile gateway device 103 executes the function corresponding to the count that has reached its upper limit. Therefore, the period for measuring the evaluation value of the MH route evaluation unit 203 is shorter than the period for gateway ON / OFF determination. When either the gateway ON count or the gateway OFF count reaches its upper limit, the mobile gateway device 103 resets the respective values ​​of the gateway ON count and the gateway OFF count. Alternative means may be employed as long as the above-mentioned objective is achieved. An alternative means is, for example, inserting a random delay before switching.

[0043] Next, the route determination operation performed by the mobile communication device 104 will be described with reference to the flowchart in Fig. 10. Fig. 10 is a flowchart showing the procedure of the route determination operation performed by the mobile communication device 104 according to the first embodiment. The mobile communication device 104 receives an RREQ from the mobile gateway device 103 or another mobile communication device 104 (S1001). In Fig. 10, the operation of step S1001 is indicated by the phrase "Receive RREQ from other node". The mobile communication device 104 determines whether the evaluation value of the RREQ stored in the MH route evaluation unit 503 is within the valid time (S1002). In Fig. 10, the operation of step S1002 is indicated by the phrase "Is the previously stored RREQ within the valid time?" If the mobile communication device 104 determines that the evaluation value of the RREQ stored in the MH route evaluation unit 503 is an evaluation value within the valid time period (Yes in S1002), it performs the operation of step S1003, and if it determines that the evaluation value of the RREQ stored in the MH route evaluation unit 503 is an evaluation value outside the valid time period (No in S1002), it performs the operation of step S1004.

[0044] In step S1003, the mobile communication device 104 determines whether the evaluation value of the newly received RREQ is greater than the evaluation value of the RREQ stored in the MH route evaluation unit 503. In Fig. 10, the operation of step S1003 is indicated by the phrase "Is it greater than the evaluation value of the previously stored RREQ?" If the mobile communication device 104 determines that the evaluation value of the newly received RREQ is greater than the evaluation value of the RREQ stored in the MH route evaluation unit 503 (Yes in S1003), it performs the operation of step S1004, and if it determines that the evaluation value of the newly received RREQ is equal to or less than the evaluation value of the RREQ stored in the MH route evaluation unit 503 (No in S1003), it performs the operation of step S1005.

[0045] In step S1004, the mobile communication device 104 stores the evaluation value of the newly received RREQ in the MH route evaluation unit 503 and transfers the RREQ from the MH communication unit 501. After performing the operation of step S1004, the mobile communication device 104 performs the operation of step S1005. In step S1005, the mobile communication device 104 determines whether the current time is within the system operation hours. If the mobile communication device 104 determines that the current time is within the system operation hours (Yes in S1005), it performs the operation of step S1001, and if it determines that the current time is outside the system operation hours (No in S1005), it ends the operation.

[0046] The route evaluation function R used in the MH route evaluation unit 203 of the mobile gateway device 103 and the MH route evaluation unit 503 of the mobile communication device 104 is given by the following equation (1).

[0047]

[0048] In formula (1), α is a weighting coefficient, and the value of α is in the range of 0<α<1. The value of α is determined, for example, by an operations manager. Hop indicates the number of hops in multi-hop communication on the corresponding route, GatewayType indicates capacity determined from the processing performance of the mobile gateway device 103 and the server communication method, and Latency indicates the actual measured value of delay in multi-hop communication. Formula (1) is an example of route evaluation function R, and route evaluation function R may be another evaluation function related to communication quality.

[0049] As explained above, according to the first embodiment, the mobile communication device 104 and the mobile gateway device 103 select RREQs for route construction to ensure a high-quality route, and the mobile gateway device 103 turns on its own gateway function only when quality cannot be ensured by the selection, thereby making it possible to achieve low-latency communication from any location in the network to the server device 102 at the minimum cost. Furthermore, the mobile gateway device 103 determines whether it will behave as the mobile gateway device 103 (ON) or as a mobile communication device in accordance with the state of the wireless multi-hop network 101, thereby contributing to the effect of collecting information from any location at the minimum cost and with low latency.

[0050] Further description will be given of the mobile communication device 104 and the mobile gateway device 103 according to the first embodiment. The mobile communication device 104 selects route establishment requests received from other mobile communication devices 104 and the mobile gateway device 103 based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality. This allows the mobile communication device 104 to achieve low-latency communication. Furthermore, the mobile communication device 104 can achieve low-latency wireless multi-hop communication at a minimum cost in any location. The above communication quality refers to the communication quality of the gateway performance, etc.

[0051] The mobile gateway device 103 selects route establishment requests received from the mobile communication device 104 and other mobile gateway devices 103 based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality. This enables the mobile gateway device 103 to achieve low-delay communication. The communication quality is the communication quality of the gateway performance, etc.

[0052] Specifically, the mobile gateway device 103 evaluates route construction requests received from the mobile communication device 104 and other mobile gateway devices 103 by a method of sorting the route construction requests based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality, and enables its own gateway function if the quality obtained by the evaluation does not reach a predetermined communication quality. This allows the mobile gateway device 103 to achieve low-latency communication. The predetermined communication quality is a communication quality that meets the communication quality requirements of applications installed in the mobile communication device 104 and other mobile gateway devices 103. The mobile gateway device 103 disables its own gateway function if the quality obtained by the evaluation reaches the predetermined communication quality. This allows the mobile gateway device 103 to reduce communication costs with the server device 102. The mobile gateway device 103 performs switching between enabling and disabling the gateway function only when predetermined conditions are met multiple times, thereby preventing overlapping of switching timing with other mobile gateway devices 103. As a result, the mobile gateway device 103 can stabilize the overall communication quality of the wireless multi-hop network 101. The predetermined conditions will be mentioned below. For example, as shown in FIG. 9 , in multi-hop communication, a case where a predetermined communication quality is met multiple times within a certain period of time is a case where the predetermined condition is met multiple times. It is assumed that the communication quality conditions are evaluated in several stages. Alternatively, a case where a predetermined communication quality is met within a certain period of time is a case where the predetermined condition is met multiple times.

[0053] Embodiment 2 In embodiment 1, the mobile gateway device 103 turns on / off the gateway function only when a predetermined condition is satisfied multiple times so that the ON / OFF timing of the gateway function does not overlap with that of other mobile gateway devices 103. In embodiment 2, the mobile gateway device 103 actively adjusts with other mobile gateway devices 103 so that the ON / OFF timing of the gateway function does not overlap.

[0054] Functional block diagrams and hardware configuration diagrams of the mobile gateway device 103 and mobile communication device 104 are omitted as they are the same as those in embodiment 1. The overall route determination operation of the mobile gateway device 103 and mobile communication device 104 is the same as the operation shown in Figures 8 and 10 of embodiment 1, so description thereof will be omitted. In embodiment 2, only the gateway ON / OFF determination process of the mobile gateway device 103 is shown in Figure 11. Figure 11 is a flowchart showing the procedure of the gateway ON / OFF determination process of the mobile gateway device 103 according to embodiment 2.

[0055] The mobile gateway device 103 determines in the gateway control unit 204 whether the route evaluation value acquired from the MH route evaluation unit 203 is equal to or greater than a threshold value (S1101). The threshold value is a predetermined value. If the mobile gateway device 103 determines that the route evaluation value acquired from the MH route evaluation unit 203 is equal to or greater than the threshold value (Yes in S1101), it performs the operation of step S1102, and if it determines that the route evaluation value acquired from the MH route evaluation unit 203 is less than the threshold value (No in S1101), it performs the operation of step S1105.

[0056] In step S1102, the mobile gateway device 103 multicasts a gateway OFF notice including an evaluation value from the gateway control unit 204 via the MH communication management unit 202. The gateway OFF notice is an action of notifying surrounding mobile communication devices 104 of information including an MH route evaluation value indicating that the gateway function of the mobile gateway device 103 will be disabled after a certain period of time. A mobile communication device 104 that was under the control of a gateway must now be under the control of another mobile gateway device 103. If the mobile gateway device 103 performing the determination and the other mobile gateway device 103 execute gateway OFF at approximately the same time, establishing a communication path to the server device 102 becomes difficult or takes time, so the gateway OFF notice is used. Thereafter, the mobile gateway device 103 determines whether it has received a gateway OFF notice from a mobile gateway device 103 with a higher evaluation value than itself within a certain period of time (S1103). The certain period of time is a predetermined time. 11, the operation of step S1103 is indicated by the phrase "Have you received a gateway OFF notice with a higher urgency than your own?" If the mobile gateway device 103 determines that it has not received a gateway OFF notice within a certain time from a mobile gateway device 103 with a higher evaluation value than itself (No in S1103), it performs the operation of step S1104, and if it determines that it has received a gateway OFF notice within the certain time from a mobile gateway device 103 with a higher evaluation value than itself (Yes in S1103), it terminates the gateway ON / OFF determination process. In step S1104, the mobile gateway device 103 turns off the gateway function. After performing the operation of step S1104, the mobile gateway device 103 terminates the gateway ON / OFF determination process.

[0057] In step S1105, the mobile gateway device 103 multicasts a gateway ON notice including an evaluation value from the gateway control unit 204 via the MH communication management unit 202. The gateway ON notice is an act of notifying surrounding mobile communication devices 104 of information including an MH route evaluation value indicating that the gateway function of the mobile gateway device 103 will be enabled after a certain time period. Thereafter, the mobile gateway device 103 determines whether or not it has received a gateway ON notice within the certain time period from a mobile gateway device 103 with a higher evaluation value than itself (S1106). In Fig. 11, the operation of step S1106 is indicated by the phrase "Has a gateway ON notice with a higher urgency than itself been received?" If the mobile gateway device 103 determines that it has not received a gateway ON notice within a certain time from a mobile gateway device 103 with a higher evaluation value than itself (No in S1106), it performs the operation of step S1107, and if it determines that it has received a gateway ON notice within a certain time from a mobile gateway device 103 with a higher evaluation value than itself (Yes in S1106), it terminates the gateway ON / OFF determination process. In step S1107, the mobile gateway device 103 turns on the gateway function. After performing the operation of step S1107, the mobile gateway device 103 terminates the gateway ON / OFF determination process.

[0058] Below, we will discuss the operation when the route evaluation function R is the above evaluation function formula (1). The mobile gateway device 103a performs a threshold determination of the evaluation value acquired from the MH route evaluation unit 203 (S1101). If the evaluation value of the mobile gateway device 103a is less than the threshold (No in S1101), a gateway ON notice is multicast transmitted (S1105). Thereafter, the mobile gateway device 103a determines whether or not it has received a gateway ON notice with a higher evaluation value than its own evaluation value from another mobile gateway device 103b, etc., within a certain period of time (S1106). A higher evaluation value means a higher level of urgency. If the mobile gateway device 103a determines that it has not received a gateway ON notice with an evaluation value higher than its own evaluation value from another mobile gateway device 103b, etc. within a certain period of time (No in S1106), it performs the operation of step S1107, and if it determines that it has received a gateway ON notice with an evaluation value higher than its own evaluation value from the mobile gateway device 103b, etc. within the certain period of time (Yes in S1106), it terminates the gateway ON / OFF determination process. In step S1107, the mobile gateway device 103a turns on the gateway function. After performing the operation of step S1107, the mobile gateway device 103a terminates the gateway ON / OFF determination process.

[0059] The gateway ON notice and gateway OFF notice are both original messages. Existing messages such as RREQ may be used instead of the gateway ON notice and gateway OFF notice. The mobile gateway device 103 may consider the gateway ON notice and gateway OFF notice only when the source is a mobile gateway device 103 within a certain number of hops from itself. The certain number of hops is set in advance.

[0060] As described above, according to the second embodiment, multiple mobile gateway devices 103 adjust the switching between enabling and disabling of the gateway function, which reduces the number of overlapping switching timings with other mobile gateway devices 103 compared to the first embodiment, thereby enabling stabilization of communication quality.

[0061] The mobile gateway device 103 can select a route construction request received from the mobile communication device 104 and other mobile gateway devices 103 using a first method of selecting the route construction request based on the number of hops and delay in wireless multi-hop communication and an evaluation value related to communication quality, a second method of evaluating the route construction request received from the mobile communication device 104 and other mobile gateway devices 103 using a method of selecting the route construction request based on the number of hops and delay in wireless multi-hop communication and an evaluation value related to communication quality, and activating its own gateway function if the quality obtained by the evaluation does not reach a predetermined communication quality, and a third method of evaluating the route construction request received from the mobile communication device 104 and other mobile gateway devices 103 using a method of selecting the route construction request based on the number of hops and delay in wireless multi-hop communication and an evaluation value related to communication quality. a third method in which evaluation is performed by selecting based on the number of hops and delay of multi-hop communication and an evaluation value related to communication quality, and disabling its own gateway function if the quality obtained by the evaluation reaches a predetermined communication quality; a fourth method in which switching between enabling and disabling the gateway function is performed only when a predetermined condition is satisfied multiple times, thereby preventing overlapping of switching timing with other mobile gateway devices 103; and a fifth method in which switching between enabling and disabling the gateway function is performed by coordinating with other mobile gateway devices 103, thereby preventing overlapping of switching timing with other mobile gateway devices 103.

[0062] 12 is a diagram showing a control circuit 801 that controls the operations executed by the mobile communication device 104 according to the first and second embodiments. The control circuit 801 causes the mobile communication device 104 to sort route establishment requests received from other mobile communication devices 104 and the mobile gateway device 103 based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

[0063] 13 is a diagram showing a control circuit 802 that controls the operations executed by the mobile gateway device 103 according to the embodiment 1 and the embodiment 2. The control circuit 802 causes the mobile gateway device 103 to sort route establishment requests received from the mobile communication device 104 and other mobile gateway devices 103 based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

[0064] 14 is a diagram showing a program storage medium 901 that stores a program for controlling the operations executed by the mobile communication device 104 according to the first and second embodiments. The program storage medium 901 stores a program for causing the mobile communication device 104 to select route establishment requests received from other mobile communication devices 104 and the mobile gateway device 103 based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

[0065] 15 is a diagram showing a program storage medium 902 that stores a program for controlling the operations executed by the mobile gateway device 103 according to the embodiments 1 and 2. The program storage medium 902 stores a program for causing the mobile gateway device 103 to sort route establishment requests received from the mobile communication device 104 and other mobile gateway devices 103 based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

[0066] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other, or part of the configuration may be omitted or modified within the scope of the gist of the invention.

[0067] 101 Wireless multi-hop network, 102 Server device, 103, 103a, 103b Mobile gateway device, 104, 104a, 104b, 104c Mobile communication device, 201, 501 MH communication unit, 202, 502 MH communication management unit, 203, 503 MH route evaluation unit, 204 Gateway control unit, 205, 504 Sensor unit, 206 Server communication management unit, 207 Server communication unit, 301, 601 Antenna for MH communication, 302 Antenna for server communication, 303, 602 MH communication interface, 304 Server communication interface, 305, 603 Processor, 306, 604 Memory, 307, 605 Storage, 308, 606 Power supply circuit, 309, 607 Battery, 405, 703 Dedicated circuit, 801, 802 Control circuit, 901, 902 program storage medium.

Claims

1. A mobile communication device that selects route establishment requests received from other mobile communication devices and mobile gateway devices based on the number of hops and delay in wireless multi-hop communication and an evaluation value related to communication quality.

2. A mobile gateway device characterized by sorting route construction requests received from mobile communication devices and other mobile gateway devices based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

3. The mobile gateway device according to claim 2, characterized in that the route construction requests received from the mobile communication device and the other mobile gateway device are evaluated by a method of sorting the route construction requests based on the number of hops and delay of the wireless multi-hop communication and an evaluation value related to the communication quality, and if the quality obtained by the evaluation does not reach a predetermined communication quality, the mobile gateway device activates its own gateway function.

4. The mobile gateway device according to claim 2, characterized in that the route construction requests received from the mobile communication device and the other mobile gateway device are evaluated by a method of selecting the route construction requests based on the number of hops and delay of the wireless multi-hop communication and an evaluation value related to the communication quality, and when the quality obtained by the evaluation reaches a predetermined communication quality, the mobile gateway device disables its own gateway function.

5. A mobile gateway device according to any one of claims 2 to 4, characterized in that the switching between enabling and disabling the gateway function is performed only when a predetermined condition is satisfied multiple times, thereby preventing overlapping of the switching timing with the other mobile gateway devices.

6. A mobile gateway device according to any one of claims 2 to 4, characterized in that the switching between enabling and disabling of the gateway function is coordinated with the other mobile gateway device to prevent overlapping of the switching timing with the other mobile gateway device.

7. A method for selecting route construction requests received from the mobile communication device and the other mobile gateway device by the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality; a method for evaluating the route construction requests received from the mobile communication device and the other mobile gateway device by a method for selecting the route construction requests by the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality, and enabling its own gateway function if the quality obtained by the evaluation does not reach a predetermined communication quality; a method for evaluating the route construction requests received from the mobile communication device and the other mobile gateway device by a method for selecting the route construction requests by the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality, and disabling its own gateway function if the quality obtained by the evaluation reaches a predetermined communication quality; a method for switching between enabling and disabling the gateway function only when a predetermined condition is satisfied multiple times, thereby preventing overlapping of switching timing with the other mobile gateway device; a method of controlling communication by some or all of the following methods: a method of coordinating with the other mobile gateway apparatus to switch between enabling and disabling a gateway function so as to prevent overlapping of switching timing with the other mobile gateway apparatus.

8. A control circuit that causes a mobile communication device to sort route construction requests received from other mobile communication devices and mobile gateway devices based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

9. A control circuit that causes a mobile gateway device to sort route construction requests received from a mobile communication device and another mobile gateway device based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

10. A program storage medium storing a program for causing a mobile communication device to select route construction requests received from other mobile communication devices and mobile gateway devices based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

11. A program storage medium storing a program for causing a mobile gateway device to select route construction requests received from a mobile communication device and other mobile gateway devices based on the number of hops and delay of wireless multi-hop communication and an evaluation value related to communication quality.

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