JP2020025193A - Wireless communication device, wireless communication system, and wireless communication method - Google Patents

Abstract

To demonstrate a different approach from a method using high quality links to create a continuous path, and provide a network with a high communication success rate even in such a highly mobile environment.SOLUTION: The wireless communication device for performing wireless communication with a fixed station for receiving all receivable communication signals including communication signals addressed to other wireless stations, includes: communication quality information holding means for holding communication quality information with other wireless stations in the periphery; destination selection means for selecting a next transfer destination of a communication signal for the fixed station with reference to communication quality information of other radio stations and designating another wireless station in the periphery of an own device as a destination of the communication signal when the own device can communicate directly with the fixed station; and transmission means for transmitting the communication signal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wireless communication device, a wireless communication system, and a wireless communication method, and can be applied to, for example, a mobile station in a multi-hop network including a base station and a plurality of mobile stations.

  Conventionally, various methods have been proposed as methods for selecting a transfer route in a network that can adopt a multi-hop configuration. For example, when each mobile station transmits data in a multi-hop manner toward a fixedly arranged base station, the base station is referred to as a "root", and each mobile station is referred to as a "node" or "leaf". It is necessary to create a tree structure in which the communication links between them are "branches".

  The quality of a network when data is transmitted from a mobile station to a base station varies depending on which branch is used. Therefore, an evaluation value (hereinafter, referred to as “link cost”) for evaluating the communication quality is given to each branch, and the sum of the link costs from each mobile station to the base station (hereinafter, referred to as “path cost”). ) Is derived and a path having a low path cost is often used (see Patent Document 1).

  Generally, the better the communication quality is, the smaller the value of the link cost is set. In addition, the base station sets its own path cost to “0”, and the mobile station that can directly receive a signal from the base station sets the base station as “parent” and sets the communication quality between itself and the base station as the path cost. This is a general operation.

JP 2015-43637 A

  By the way, for example, when the mobile station moves rapidly, the mobile station may move between the time when the route is formed and the time when data is transmitted. Therefore, there is a high possibility that the formed route is not an optimal route as compared with a case where movement is not assumed.

  For this reason, conventionally, it is general to configure a network using sufficiently high quality links in anticipation of movement fluctuations of mobile stations.

  However, in the above-mentioned method, as a result, a communicable link is not used, and there is a problem that a communication success rate is reduced.

  Therefore, the present invention proposes a method different from the direction of using a high-quality link and forming an unbroken path, and aims to provide a network having a high communication success rate even in such a moving environment. is there.

  In order to solve such a problem, a first aspect of the present invention provides a wireless communication apparatus that performs wireless communication with a fixed station that receives all receivable communication signals including communication signals addressed to other wireless stations. 1) communication quality information holding means for holding communication quality information with other nearby wireless stations; and (2) next transfer of a communication signal to a fixed station by referring to communication quality information of other wireless stations. Transmission destination selection means for specifying a destination of another communication station near the own device when the own device can directly communicate with the fixed station, and (3) a communication signal And transmitting means for transmitting the data.

  The second invention includes a fixed station that receives all receivable communication signals including communication signals addressed to other wireless stations, and a plurality of mobile stations according to the first invention.

  According to a third aspect of the present invention, there is provided a wireless communication method for performing wireless communication with a fixed station receiving all receivable communication signals including communication signals addressed to other wireless stations. And (2) the transmission destination selecting means refers to the communication quality information of the other radio station and transmits the next transmission destination of the communication signal to the fixed station. When the own device can directly communicate with the fixed station, another wireless station in the vicinity of the own device is designated as the destination of the communication signal, and (3) the transmitting means transmits the communication signal. I do.

  According to the present invention, it is possible to provide a network having a high communication success rate even in an environment where movement is severe.

1 is an overall configuration diagram illustrating an example of an overall configuration of a wireless communication system (network) according to an embodiment. FIG. 3 is an internal configuration diagram illustrating an example of an internal configuration of a mobile station according to the embodiment. FIG. 3 is an explanatory diagram illustrating an example of a link cost in the wireless communication system according to the embodiment. FIG. 9 is an explanatory diagram illustrating a destination selection process according to the embodiment; FIG. 9 is an explanatory diagram illustrating a destination selection process according to the embodiment; FIG. 9 is an explanatory diagram illustrating a destination selection process according to the embodiment; FIG. 9 is an explanatory diagram illustrating a destination selection process according to the embodiment;

(A) Main Embodiment Hereinafter, main embodiments of a wireless communication device, a wireless communication system, and a wireless communication method according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of Embodiment [Overall Configuration of System]
FIG. 1 is an overall configuration diagram illustrating an example of an overall configuration of a wireless communication system (network) according to this embodiment.

  1, a wireless communication system 1 according to this embodiment includes a fixedly installed base station 10 and a plurality (eight in FIG. 1) of mobile stations 20 (20-1 to 20-8).

  The wireless communication system 1 forms a wireless multi-hop network having a tree structure in which the base station 10 is a “root”, and each mobile station 20 is a “node” and a “leaf”. The number of base stations 10 and mobile stations 20 is not limited. Hereinafter, the base station 10 and each mobile station 20 may be collectively referred to as a “station” or a “node”.

  In FIG. 1, a straight line connecting the stations indicates that the two stations can communicate with each other. Each station (each node) constituting the wireless multi-hop network can be, for example, one that can support communication using IEEE 802.15.4. Note that the wireless communication system is not limited to IEEE 802.15.4 as long as wireless multi-hop communication is possible between stations.

  A unique address (for example, a MAC address, a short address, an IP address, etc.) on the network is assigned to the base station 10 and each mobile station 20. Communication is performed between the base station 10 and each mobile station 20, but no communication is performed between the mobile stations 20. That is, each mobile station 20 transmits a unicast data packet destined for the base station 10 as a final destination, but transmits a unicast data packet destined for another mobile station 20 as a final destination. No transmission is performed. If communication between the mobile stations 20 is required, the communication may be performed by relaying the base station 10.

  In the wireless communication system 1 according to this embodiment, for example, a person (human body) competing in an athletic field, an athletic field, or the like is a mobile body, and a wireless communication device as the mobile station 20 is fixed in contact with the human body. Assume the case. The method of fixing the wireless communication device in contact with the human body is not particularly limited, and various methods can be applied. For example, the wireless communication device can be attached to a wearing device such as a band or a vest-type wearing clothing. There is a method such as fixing.

  This is because, for example, one or a plurality of sensors are mounted on the mobile station 20 and pulse data and heart rate data of the human body are acquired at a position where each sensor is fixed, and each mobile station 20 Is assumed to be transmitted to the base station 10. In other words, it is assumed that each mobile station 20 transmits sensing data such as pulse data and heart rate data of a human body that is exercising or competing toward the base station 10, and the base station 10 collects each sensing data.

  The type of data to be sensed is not particularly limited. The position where the wireless communication device is fixed to the moving object is not particularly limited, and is appropriately determined according to the data to be measured, the type of exercise, and the like. When each station performs wireless communication, the human body may become an obstacle depending on the positional relationship between the stations, so the presence or absence of the obstacle affects the communication quality.

[Base station and mobile station]
The base station 10 is a fixedly arranged wireless communication device (wireless device), and manages the entire wireless communication system 1. The base station 10 is also called a fixed station. The base station 10 receives information (packet) including data from each mobile station 20 and collects data by multi-hop communication. Note that the data collected by the base station 10 may be stored in the base station 10 or may be provided to an information processing device that is connected to the base station 10 wirelessly or by wire. This embodiment does not particularly limit the use of the collected data.

  The base station 10 has an operation mode in which all receivable packets are received, not just packets addressed to itself. This operation mode is generally called a promiscuous mode (promiscuous mode). In general, a network interface (not shown) of the base station 10 receives a packet addressed to the own device from among the incoming packets and notifies the host system. On the other hand, the promiscuous mode is an operation mode in which not only packets addressed to the own device but also all incoming packets including packets not addressed to the own device are received indiscriminately and notified to the upper system. The significance of the network interface of the base station 10 operating in the promiscuous mode in this embodiment will be described later.

  Each mobile station 20 (20-1 to 20-8) is a wireless communication device (wireless device) attached to a mobile object. In this embodiment, the description will be made assuming that the moving object is a human. However, as the moving object, a movable object such as a bicycle, an automobile, a movable robot, or an unmanned aerial vehicle can be widely applied.

  Each mobile station 20 has a sensor. The sensor measures the measurement target constantly or intermittently (meaning includes periodic and periodic), and each mobile station 20 transmits a packet including data measured by its own sensor to the base station 10. Multi-hop transmission as final destination.

  Each mobile station 20 has a sensor, whereas the base station 10 does not have a sensor, but their functions are different, but the basic functions of the mobile station 20 and the base station 10 are the same. be able to. Hereinafter, the internal configuration of the mobile station 20 among the mobile stations 20 and the base station 10 will be described with reference to FIG.

  FIG. 2 is an internal configuration diagram illustrating an example of the internal configuration of the mobile station 20 according to this embodiment.

  In FIG. 2, a wireless communication apparatus according to this embodiment includes a transmitting unit 1001, a receiving unit 1002, a timer 1003, a beacon packet generating unit 1004, a data generating unit 1005, a transmission destination selecting unit 1006, a beacon receiving unit 1007, a beacon managing unit 1008, a data receiving unit 1009, a movement measuring unit 1010, and a peripheral wireless device table 1011.

  The mobile station 20 includes devices such as a CPU, a ROM, a ROM, an EEPROM, an input / output interface, a communication unit (wireless interface), a sensor, and the like. Various functions in the mobile station 20 are realized by a CPU (computer) executing a processing program (wireless communication program). The system may be constructed by installing a wireless communication program. Even in such a case, the wireless communication program can be represented as each element shown in FIG.

  The transmitting unit 1001 has a function of transmitting a radio wave obtained by modulating a carrier with a beacon signal or a data signal. The receiving unit 1002 has a function of demodulating an incoming radio wave to obtain a received signal, providing a beacon signal to the beacon receiving unit 1007, and providing a data signal to the data receiving unit 1009.

  Note that the transmitting means 1001 and the receiving means 1002 are connected to an antenna unit not shown in FIG. The transmitting means 1001 and the receiving means 1002 constitute a wireless interface (packet transmitting / receiving means) for transmitting and receiving wireless signals. The mobile station 20 transmits and receives beacon packets between stations, and transmits and receives data packets including data such as pulse data of a human body.

  The beacon receiving unit 1007 has a function of receiving, via the receiving unit 1002, a beacon signal periodically transmitted from the base station 10 by flooding. The beacon receiving unit 1007 supplies the received power value at the time of receiving the beacon to the beacon managing unit 1008, and also includes the moving speed of the transmitting station, the path cost of the transmitting station, and the transmitting station if necessary, which are included in the beacon signal. Or the like to the beacon management unit 1008.

  The movement measuring unit 1010 has a function of acquiring information on the movement state of the own station. As the movement measurement unit 1010, for example, a part or all of an acceleration sensor, a gyro sensor, an acceleration sensor, an angular acceleration sensor, a geomagnetic sensor, and the like can be applied. The movement measuring unit 1010 provides the beacon management unit 1008 with a result related to the movement state of the own station to transmit the measurement result related to the movement state of the own station included in the beacon signal. Note that the movement measuring unit 1010 is not an essential element of this embodiment.

  The beacon management unit 1008 acquires the beacon signal received from the beacon reception unit 1007, and has a function of managing the beacon signal and controlling the transfer of the beacon signal. The beacon management unit 1008 obtains the path cost of the transmitting station included in the beacon from the beacon receiving unit 1007 (that is, the path cost associated with the identification information of the transmitting station), and obtains another mobile station in the vicinity. In order to hold the path cost of 20, the path cost of the transmitting station is stored in the peripheral wireless device table 1011.

  The beacon management unit 1008 receives the received power value at the time of receiving the beacon from the beacon receiving unit 1007 and the moving distance (moving speed) per fixed time measured by the movement measuring unit 1010, and receives the received power value at the time of receiving the beacon. The link cost between the stations may be obtained based on and the moving speed of the own station.

  Further, the beacon management unit 1008 refers to the peripheral wireless device table 1011 to select a route having the smallest value of the link cost from the own station to the base station 10, and to select a route when communication is performed using the route. Determine the station path cost.

  The timer 1003 is a timer for managing a delay (a packet transfer delay time) from when a flooding packet is received from another station to when the flooding packet is transferred.

  The beacon packet generation unit 1004 has a function of generating a beacon packet to be flooded. The beacon packet generation means 1004 includes the path cost of the own station, the moving distance of the own station as a transmitting station, the position information of the own station as necessary, and the like in the beacon packet.

  The data receiving unit 1009 has a function of receiving, via the receiving unit 1002, a data packet transmitted from another station. The data receiving means 1009 gives the data packet after the receiving processing to the transmission destination selecting means 1006. For example, when transferring the received data packet to the next station, the data receiving means 1009 supplies the data packet to the destination selection means 1006 in order to transfer the data packet to the next station.

  The data generation unit 1005 has a function of generating data to be transmitted to the base station 10. For example, pulse data of the human body is generated, but the data type is not particularly limited. The data transmission trigger of the data generation unit 1005 is not particularly limited. For example, data generated in an upper layer (an application (not shown) or the like) can be used as transmission data.

  The peripheral wireless device table 1011 is a table including information on other mobile stations 20 located in the vicinity. The peripheral wireless device table 1011 stores, for example, information such as the address information of the peripheral mobile station 1011, the number of hops to the base station 10, the path cost, the received power value, and the like. As the peripheral wireless device table 1011, a route table to the base station 10 or the like can be applied.

  The transmission destination selection unit 1006 has a function of selecting a transfer destination of a packet including data generated by the data generation unit 1005 or a data packet received by the data reception unit 1009.

  The transmission destination selection unit 1006 refers to the peripheral wireless device table 1011 to select a route having the minimum cost from the route from the own station to the base station 10, and to select a next mobile station (next Mobile station address) is designated as the data transfer destination. Then, the data packet specifying the transfer destination is supplied to the transmitting unit 1001, and the data packet is transmitted from the transmitting unit 1001 to the transfer destination.

  In addition, when the own station 20 can directly communicate with the base station 10, the transmission destination selecting unit 1006 specifies another mobile station 20 existing around the own station as the destination of the data packet.

  As described above, when the own station 20 can directly communicate with the base station 10, the route of the data packet can be bypassed by designating another nearby mobile station 20 as the destination. Since the base station 10 operates in the procas mode, when a data packet addressed to another mobile station 20 reaches the base station 10 directly, the base station 10 can receive the data packet as it is. . Further, even when the communication quality of the link between the own station 20 and the base station 10 is poor, if the data packet transmitted on the bypass route reaches the base station 10, the base station 10 may not receive the data packet. it can. A detailed description of a method of selecting a transmission destination by the transmission destination selection unit 1006 will be described in detail in the section of operation.

[Link cost]
FIG. 3 is an explanatory diagram illustrating an example of a link cost in the wireless communication system 1 according to the embodiment.

  In FIG. 3, a thick line indicates a data transfer path between stations, and a dotted line indicates a link not used for transfer. The numbers enclosed in squares added to each link indicate link costs, and the numbers added to each mobile station 20 indicate path costs of each mobile station. Note that the path cost of the base station 10 is “0”.

  For example, the transfer route from the mobile station 20-6 to the base station 10 is “mobile station 20-6” → “mobile station 20-4” → “base station 10”. In this case, since the value of the link cost between the mobile station 20-4 and the base station 10 is “4”, the value of the path cost of the mobile station 20-4 that transfers data to the base station 10 is “4”. ". The value of the link cost between the mobile station 20-6 and the mobile station 20-4 is "2". Accordingly, the value of the path cost of the mobile station 20-6 when the mobile station 20-6 transmits data to the base station 10 with the mobile station 20-4 as a transfer destination is “6 (= 2 + 4)”.

  The link cost is a value obtained by evaluating the communication quality of a communication path between stations. There are various ways of evaluating the link. For example, the communication quality of the communication path is evaluated by using a value within a range such as “1 to 99” or “1 to 9999”. Generally, it is evaluated that the smaller the value, the better the communication quality, and the larger the value, the worse the communication quality. That is, if the value of the link cost is “1”, it is determined that the communication quality of the communication path is good.

(A-2) Operation of Embodiment Next, the operation of the wireless communication process in the wireless communication system 1 according to this embodiment will be described in detail with reference to the drawings.

(A-2-1) Network Configuration Operation The wireless communication system 1 is a wireless multi-hop network, and an example of the operation will be described. Communication control algorithms such as route determination (routing) in a network are not limited.

  A unique address (for example, a MAC address, a short address, and the like) is assigned to the base station 10 and each mobile station 20 that configure the network.

  Hereinafter, a method of configuring a network including the base station 10 and each mobile station 20 will be described.

  Here, it is assumed that a wireless communication device (mobile station 20) is attached to a person who performs a game or exercise in a stadium or an athletic field, and the person runs and moves violently. Therefore, since the mobile station 2 moves much, the network may need to be reconfigured frequently (for example, every second).

  Therefore, for example, the base station 10 transmits a beacon packet at a predetermined timing. More specifically, the base station 10 transmits a beacon packet every second. Each mobile station 20 that has received the beacon packet transmits the beacon packet after a random time. By doing so, the beacon signal is spread over the entire network.

  This operation is called flooding. The beacon packet transmitted by each station includes the path cost, moving speed, position information, and the like of the own station (the transmitting station of the beacon packet). For example, a configuration example of a network will be described with reference to FIG.

  When the base station 10 transmits a beacon packet, the mobile stations 20-1, 20-3, 20-5, and 20-7 existing within the radio wave range of the base station 10 directly receive the beacon packet.

  In each mobile station 20 that has received the beacon packet, the receiving unit 1002 captures the radio wave and measures the received power value at the time of receiving the beacon. The beacon receiving unit 1007 supplies the received power value of the receiving unit 1002 at the time of receiving the beacon and the received beacon packet to the beacon managing unit 1008.

  The beacon management unit 1008 extracts the path cost of the transmitting station included in the beacon packet and stores the path cost of the transmitting station in the peripheral wireless device table 1011. Here, since the path cost of the base station 10 is set to “0”, each mobile station 20 that directly receives the beacon packet from the base station 10 stores the path cost “0” of the base station 10 in the peripheral radio table. 1011.

  On the other hand, when the transmitting station of the beacon packet is the mobile station 20, the path cost of the transmitting station (mobile station 20) of the beacon packet is included in the beacon packet. Is stored in the peripheral wireless device table 1011.

  The beacon management unit 1008 receives the received power value at the time of receiving the beacon, the measurement result of the movement status of the own station from the movement measurement unit 1010 (for example, the movement amount within a predetermined time (movement speed)), and the like. The link cost of the communication path between the packet transmitting station (the base station 10 or the mobile station 20) and the own station is derived. Then, the link cost is stored in the peripheral wireless device table 1011.

  The link cost deriving method by the beacon management unit 1008 is not particularly limited in this embodiment, and various methods can be used. For example, the link cost may be derived based on a comparison result between the magnitude of the received power value of the beacon signal from the transmitting station and a preset threshold. Also, for example, a link cost table in which link costs are defined based on the relationship between the reception power value and the distance between the transmission station and the own station is prepared in advance, and the reception power value, the transmission station The link cost may be derived based on the movement amount.

  Immediately before the beacon packet, each mobile station 20 selects a path having the minimum cost from the path from the own station to the base station 10, and selects the next station on the path as a parent node. Then, the path cost of the route passing through the parent node is obtained, and the path cost is set as the path cost of the own station.

  The beacon packet generation unit 1004 floods a beacon packet in which at least the path cost of the own station and the moving speed of the own station are inserted. Each mobile station 20 floods the beacon packet at random times.

  By sequentially flooding the beacon packets as described above, even if each mobile station 20 moves rapidly or moves with rotation, the link cost between the stations can be updated successively.

(A-2-2) Processing at the Time of Data Transmission Next, processing when each mobile station 20 transmits a packet including data to the base station 10 will be described.

  When each mobile station 20 performs data communication toward the base station 10, the transmission destination selection unit 1006 refers to the peripheral wireless device table 1011 to determine a path from the own station to the base station 10 where the path cost has the minimum value. select.

  The transmission destination selection means 1006 sets the mobile station 20 next to the path having the minimum path cost as a parent node, and transmits a data packet to the parent node. That is, the transmission destination selection unit 1006 generates a data packet including the address of the parent node, and the transmission unit 1001 transmits the data packet.

  By repeating the above data transmission processing between the mobile stations 20, the data packet is transmitted to the base station 10 by multi-hop transmission.

(A-2-3) Transmission Destination Selection Processing Next, the operation of the transmission destination selection processing when the parent node selected by each mobile station 20 is the base station 10 will be described with reference to the drawings.

  4 to 7 are explanatory diagrams illustrating the destination selection process according to the embodiment.

[Basic concept using promiscuous mode]
According to the network configuration method described above, it is possible to configure a network substantially as intended. However, when each mobile station 20 moves, the state of the link between the stations changes every moment, so that it is assumed that data communication will fail. For example, if a human body or the like exists between the stations, the human body becomes an obstacle, the communication quality of the link between the stations is reduced, and the communication may fail.

  For example, a case where the mobile station 20-B moves from the position B1 to the position B2 will be described with reference to FIG.

  The route formed when the mobile station 20-B is at the position of B1 is “mobile station 20-B (second hop)” → “mobile station 20-A (first hop)” → “base station 10”. And Then, the mobile station 20-B moves from the position B1 to the position B2, and the mobile station 20-B transmits a data packet to the mobile station 20-A at the position B2 (S30).

  However, at this time, if an obstacle (for example, a human body) exists between the mobile station 20-B and the mobile station 20-A at the position of B2, the mobile station 20-B and the mobile station 20-A will not be connected. The communication quality of the link between the two may be degraded and communication may fail (S31).

  Although not shown in FIG. 4, an obstacle may exist between the mobile station 20-A and the base station 10, for example. That is, if the communication quality of one or both of the link of “mobile station 20-B → mobile station 20-A” and the link of “mobile station 20-A → base station 10” deteriorates, communication fails. May occur.

  Therefore, in this embodiment, the base station 10 operates in the promiscuous mode. Therefore, even when the mobile station 20-B is transmitting a data packet addressed to the mobile station 20-A, the base station 10 transmits the mobile station 20-A transmitted by the mobile station 20-B that has become directly communicable. The data packet addressed to the destination can be received (S32).

  As a result, even if the communication quality of one or both of the link of “mobile station 20-B → mobile station 20-A” and the link of “mobile station 20-A → base station 10” deteriorates, If the communication quality of the link from the "station 20-B to the base station 10" is good, communication failure can be avoided.

[Transmission destination selection processing when parent node is base station 10]
When the above-described method is used, the mobile station 20 that can directly communicate with the base station 10 usually specifies the base station 10 as the destination of the data packet.

  However, even when the base station 10 assumes the promiscuous mode, communication may fail when the link between the mobile station at the first hop and the base station 10 becomes unavailable.

  For example, as shown in FIG. 5, there is a case where an obstacle exists between the base station 10 and the mobile station 20-A that can directly communicate with the base station 10. In such a case, the mobile station 20-A at the first hop position from the base station 10 specifies the base station 10 as the destination of the data packet. The link of “mobile station 20-A → base station 10” cannot be used, and no alternative exists.

  Therefore, even when the mobile station 20 can directly communicate with the base station 10, another mobile station 20 existing around the own station is designated as the destination of the data packet. That is, when the transmission destination selection unit 1006 refers to the peripheral wireless device table 1011 and designates (selects) the base station 10 as the destination of the data packet, the destination selection unit 1006 does not designate the base station 10 as the destination, but performs Mobile station 20 is designated.

  By doing so, even when the communication quality of the link between the mobile station 20 and the base station 10 that can directly communicate with the base station 10 is poor, the data packet transfer path can be bypassed, and communication failure occurs. Can be avoided.

  Here, an example of a method in which the transmission destination selection unit 1006 selects another mobile station 20 in the vicinity when the own station 20 can directly communicate with the base station 10 will be described.

[Selection method 1]
The transmission destination selection unit 1006 selects another mobile station 20 existing near the base station 10.

  The selection method 1 is intended to detour a data packet by a route with the shortest cost by designating another mobile station 20 existing near the base station 10 as a destination of the data packet.

  As an example of a method of selecting another mobile station 20 existing near the base station 10, there is a method of referring to a value of a path cost of another mobile station 20 in the vicinity. In consideration of the relationship between the distance between the stations and the value of the path cost, when the distance between the stations is short, the value of the path cost tends to be small. Therefore, the destination selection unit 1006 refers to the peripheral wireless device table 1011 and selects another mobile station 20 having the minimum path cost value.

  For example, in FIG. 6, the description will focus on a mobile station 20-A that can directly communicate with the base station 10. It is assumed that mobile stations 20-C and 20-D exist around the mobile station 20-A. In this example, for ease of explanation, it is assumed that both mobile stations 20-C and 20-D are stations that can directly communicate with base station 10.

  The value of the link cost between the mobile station 20-C and the base station 10 is “2”, and the value of the path cost of the mobile station 20-C is “2”. On the other hand, the value of the link cost between the mobile station 20-D and the base station 10 is “4”, and the value of the path cost of the mobile station 20-D is “4”.

  In this example, the transmission destination selection unit 1006 refers to the peripheral wireless device table 1011 and specifies the mobile station 20-C having the minimum path cost value as the destination of the data packet.

[Selection method 2]
The transmission destination selection unit 1006 selects another mobile station 20 located at a position distant from the own station 20 to some extent.

  The selection method 2 considers a case where a plurality of obstacles can exist around the own station 20. For example, assume a network configuration in which a mobile station 20 is attached to a soccer player and the base station 10 is fixed to a goal post. When many players are crowded near the goal post and competitive play is performed, the bodies of a plurality of players can be obstacles. In addition, the body of the player (moving body) who is equipped with the wireless communication device may also be an obstacle. Therefore, even if a data packet is transmitted to the base station 10 or another mobile station 20 near the own station 20, the link between the stations may be blocked, or depending on the player's own body orientation, the player's own body may be lost. The body may affect the communication quality and the communication may fail.

  Therefore, in the selection method 2, another mobile station 20 existing at a position distant from the own station 20 to some extent is specified. By doing so, the communication failure can be avoided by bypassing the data packet to another mobile station 20 considered to have relatively good communication quality.

  As an example of a method of selecting another mobile station 20 located at a position distant from the own station 20 to some extent, there is a method of referring to a received power value of a beacon received by the own station 20. Considering the relationship between the distance between the stations and the received power value, there is a tendency that the longer the distance between the stations is, the smaller the received power value of the beacon is. Therefore, the transmission destination selection unit 1006 refers to the peripheral wireless device table 1011 and selects another mobile station 20 whose beacon reception power value is equal to or less than a predetermined threshold. Note that the threshold can be appropriately determined according to the operation.

  When the received power value is compared with the threshold, if there are a plurality of received power values that are equal to or less than the threshold, another mobile station 20 selected at random from the plurality of received power values may be used. . As another method, among the plurality of received power values, another mobile station 20 having the highest or lowest received power value may be selected.

  For example, in FIG. 7, a description will be given focusing on a mobile station 20-A that can directly communicate with the base station 10. It is assumed that mobile stations 20-C, 20-D, and 20-E exist around the mobile station 20-A. It is assumed that among the received power values of the beacons of the mobile stations 20-C, 20-D, and 20-E, the received power value of the beacon of the mobile station 20-E is equal to or less than the threshold. In the case of this example, the transmission destination selection unit 1006 refers to the peripheral wireless device table 1011 and specifies the mobile station 20-E having a reception power value equal to or less than the threshold value as the destination of the data packet. In the case of this example, the data packet is transmitted on the route of “mobile station 20-E → mobile station 20-C → base station 10”.

  As described above, the transmission destination selection unit 1006 can select the destination of the data packet by using either the selection method 1 or the selection method 2.

  Here, in FIGS. 6 and 7, the base station 10 operates in the promiscuous mode. Therefore, when there is no obstacle between the mobile station 20-A and the base station 10, the base station 10 receives the data packet transmitted from the mobile station 20-A and addressed to another mobile station 20. can do.

  When there is no obstacle between the mobile station 20-A and the base station 10, the base station 10 transmits the data packet transmitted by the mobile station 20-A and the data packet transmitted through another mobile station 20. And may arrive. However, in this case, the base station 10 can solve the problem by receiving the data packet arriving earlier or discarding the data packet arriving later.

  In addition, by designating another mobile station 20 as the destination of the data packet and transmitting the data packet, the number of relays of the data packet increases, which may cause a problem that the communication of the other mobile station is affected. However, in this embodiment, it is considered that there is no problem in the above point.

  This is because, in this embodiment, the timing at which the data packet is transmitted from each mobile station 20 to the base station 10 is assigned a time zone, for example, in the TDMA system. Specifically, a method of assigning a specific time zone to each mobile station 10 according to the elapsed time of the beacon signal transmitted by the base station 10 can be applied. With such a configuration, even if the number of relays from the mobile station 20 to the base station 10 increases, there is no adverse effect on the communication of another mobile station 20 due to the increase in the number of communication. Note that the uplink communication is not limited to the communication operation such as the TDMA system, and it is possible to adopt a configuration in which the transmission operation is performed while avoiding the collision by the ordinary CSMA. In other words, any method may be used as long as each mobile station 20 performs a transmission operation while adjusting the transmission timing of other nearby mobile stations 20.

(A-3) Effects of Embodiment As described above, according to this embodiment, in a multi-hop network in a highly mobile environment, the use of promiscuous mode and the selection of a parent (data packet) (Selection of a transmission destination), it is possible to reduce the probability of communication failure as compared with a case where a received power value or the like is simply used. As a result, the data collection success rate can be increased.

(B) Other Embodiments Although various modified embodiments have been described in the above-described embodiments, the present invention can be applied to the following modified embodiments.

  (B-1) In the mobile station capable of directly communicating with the base station, the method in which the transmission destination selection unit specifies the destination of the data packet is not limited to the selection method 1 and the selection method 2 in the above-described embodiment.

  For example, depending on the type of competition / exercise, it is conceivable that a plurality of specific mobile stations make similar movements. For example, when a mobile station is attached to a player, a manager, or a coach of the same team in a competition such as soccer, it is possible that the players make a collective movement. In such a situation, by preferentially selecting a specific mobile station (that is, a mobile station attached to a specific player or a manager / coach), there is a possibility that deterioration of communication characteristics due to movement can be prevented. For such a purpose, it is conceivable to assign a group number to each mobile station and transmit the beacon including the group number. Accordingly, each mobile station that has received the beacon can identify a beacon from a mobile station belonging to the group based on the group number included in the beacon. That is, the destination selection means can select a specific mobile station belonging to the group.

  Further, for example, a mobile station that can directly communicate with a base station may fixedly set a station to be specified as a destination in advance. The station is provided, for example, near the boundary of the radio wave arrival range of the fixedly installed base station 10, and a mobile station located one hop from the base station specifies the station as a destination of a data packet. Is also good.

  Further, in the above-described embodiment, the case where either the selection method 1 or the selection method 2 is used is illustrated, but the selection method 1 and the selection method 2 may be switched and used depending on the situation.

DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 10 ... Base station, 20 (20-1 to 20-8, 20-A to 20-E) ... Mobile station,
1001 transmission means, 1002 reception means, 1003 timer, 1004 beacon packet generation means, 1005 data generation means, 1006 destination selection means, 1007 beacon reception means, 1008 beacon management means, 1009 data reception Means 1010: movement measuring means, 1011: peripheral wireless device table.

In order to solve such a problem, a first aspect of the present invention is a wireless communication system for performing wireless multi-hop communication of a communication signal to a fixed station that receives all receivable communication signals including communication signals addressed to other wireless stations. In the communication device, (1) a path cost value which is a sum of link cost values of respective routes from other surrounding wireless stations to a fixed station , using an evaluation value obtained by evaluating communication quality of a communication path between stations as a link cost value. (2) a communication quality information holding means for holding a communication signal to a fixed station based on each path cost value of another wireless station and a link cost value between the own apparatus and a peripheral station . The next transfer destination is selected, and when the own device can directly communicate with the fixed station, the other wireless stations in the vicinity of the own device are referred to by referring to each path cost of the other nearby wireless stations. Destination selection means for designating a communication signal destination; and (3) a communication signal And a sending unit signal for.

According to a third aspect of the present invention, there is provided a wireless communication method for performing wireless multi-hop communication of a communication signal toward a fixed station that receives all receivable communication signals including communication signals addressed to other wireless stations. The quality information holding unit sets a path cost value , which is a sum of link cost values of the respective routes from other surrounding radio stations to the fixed station , as an evaluation value obtained by evaluating the communication quality of the communication path between the stations as a link cost value. (2) the transmission destination selection means, based on each path cost value of the other radio station and the link cost value between its own device and the peripheral station, When the own device can directly communicate with the fixed station, the other wireless stations in the vicinity of the own device are communicated with reference to each path cost of other nearby wireless stations. (3) The transmission means transmits a communication signal. To.

As described above, when the own station 20 can directly communicate with the base station 10, the route of the data packet can be bypassed by designating another nearby mobile station 20 as the destination. Since the base station 10 is operating in a professional promiscuous mode, data packets of another mobile station 20 destined directly when arriving at the base station 10, the base station 10 as it is able to receive data packets it can. Further, even when the communication quality of the link between the own station 20 and the base station 10 is poor, if the data packet transmitted on the bypass route reaches the base station 10, the base station 10 may not receive the data packet. it can. A detailed description of a method of selecting a transmission destination by the transmission destination selection unit 1006 will be described in detail in the section of operation.

For example, in FIG. 7, a description will be given focusing on a mobile station 20-A that can directly communicate with the base station 10. It is assumed that mobile stations 20-C, 20-D, and 20-E exist around the mobile station 20-A. It is assumed that among the received power values of the beacons of the mobile stations 20-C, 20-D, and 20-E, the received power value of the beacon of the mobile station 20-E is equal to or less than the threshold. In this example, destination selection unit 1006, with reference to the surrounding radio table 1011, the following received power value der Ru mobile station 20-E threshold, specified as a destination of the data packet. In the case of this example, the data packet is transmitted on the route of “mobile station 20-E → mobile station 20-C → base station 10”.

In this embodiment, the timing of transmitting the data packet to the base station 10 from the mobile station 20, for example, that have time zone allocated as TDMA system. Specifically, a method of assigning a specific time zone to each mobile station 10 according to the elapsed time of the beacon signal transmitted by the base station 10 can be applied. With such a configuration, even if the number of relays from the mobile station 20 to the base station 10 increases, there is no adverse effect on the communication of another mobile station 20 due to the increase in the number of communication. Note that the uplink communication is not limited to the communication operation such as the TDMA system, and it is possible to adopt a configuration in which the transmission operation is performed while avoiding the collision by the ordinary CSMA. In other words, any method may be used as long as each mobile station 20 performs a transmission operation while adjusting the transmission timing of other nearby mobile stations 20.

Claims (6)

In a wireless communication device that wirelessly communicates with a fixed station that receives all receivable communication signals, including communication signals addressed to other wireless stations,
Communication quality information holding means for holding communication quality information with other wireless stations in the vicinity,
With reference to the communication quality information of the other radio station, to select the next transfer destination of the communication signal for the fixed station, when the own device can directly communicate with the fixed station, Transmission destination selection means for designating the other wireless station around the own device as a destination of the communication signal,
A wireless communication device comprising: a transmission unit configured to transmit the communication signal.   The transmission destination selection unit refers to the communication quality information of the other wireless stations in the vicinity, and among the other wireless stations in the vicinity, another wireless station whose estimated distance to the fixed station is relatively small. 2. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is designated as a destination of the communication signal.   The transmission destination selecting means refers to the communication quality information of the other wireless stations in the vicinity, and among the other wireless stations in the vicinity, another wireless station whose estimated distance to the own device is relatively large, The wireless communication device according to claim 1, wherein the wireless communication device is designated as a destination of the communication signal. Of the other wireless stations in the vicinity, the same group is given a preset group number,
2. The wireless communication apparatus according to claim 1, wherein the transmission destination selection unit preferentially designates the another wireless station to which the group number is assigned. A fixed station that receives all receivable communication signals, including communication signals addressed to other wireless stations,
A wireless communication system comprising: a plurality of mobile stations according to any one of claims 1 to 4. In a wireless communication method for performing wireless communication with a fixed station that receives all receivable communication signals including communication signals addressed to other wireless stations,
Communication quality information holding means holds communication quality information with other wireless stations in the vicinity,
The transmission destination selecting means refers to the communication quality information of the other wireless station and selects a next transfer destination of a communication signal directed to the fixed station. When communication is possible, the other wireless station around the own device is designated as the destination of the communication signal,
A wireless communication method, wherein a transmitting unit transmits the communication signal.

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