JP4321298B2 - Communication system and method - Google Patents

Description

  The present invention relates to a communication system and method, and is suitably applied to, for example, a wireless LAN (local area network).

  In portable terminals such as mobile phones and PDAs, a battery is used as a power source, and a wireless LAN is used as a data communication method, thereby eliminating wiring from the terminal. And in order to lengthen the operation possible time of a terminal with the limited electric power with a battery, it is requested | required that there is little power consumption in a portable terminal.

  Therefore, a general portable terminal has a power saving function.

  For example, some portable terminals having a wireless LAN function include a power saving mode in which, when data transmission is not performed, the operation is performed with as little power as possible to detect data reception.

In the technology disclosed in Patent Document 1 below, the distance between the terminals, the radio wave condition, or the data processing capability at that time are inspected, and after selecting a terminal suitable for relaying, data communication is performed via the terminal. Do. A terminal close to the data transmission source terminal, a terminal with a good radio wave condition, or a terminal with high data processing capability at that time is selected as a terminal suitable for relaying.
JP 2002-135195 A

  However, in the power saving mode described above, it is necessary to repeatedly transmit at least control packets (for example, routing packets) at regular intervals, and power consumption is unavoidable, limiting power consumption savings. There is.

  In addition, it is possible to adopt a configuration in which only the reception is performed without transmitting the control packet in the power saving mode. However, depending on the specification of the control protocol, a certain mobile terminal may not perform the reception but also the transmission. There is a high possibility that the control will not be established, and even if it is established, at least reception must be performed, so that power consumption for performing the reception operation occurs.

In order to solve such a problem, in the first aspect of the present invention, in a communication system having a plurality of first NW communication terminals belonging to a first network and a plurality of second NW communication devices belonging to a second network, the first NW Each of the communication terminals includes a first communication processing unit for performing wireless communication with another first NW communication terminal via the first network, and a second communication processing unit for performing wireless communication with the second NW communication device. Each of the second NW communication devices has terminal information relating to the first NW communication terminal capable of communicating with itself, which has a narrower cover area capable of wireless communication than the first communication processing unit of the first NW communication terminal. Terminal information holding means for holding, and storage means for collecting and storing terminal information held by another second NW communication device, wherein each of the first NW communication terminals has another first NW When trying to start communication with the communication terminal, the second NW communication device capable of communicating with itself acquires the terminal information accumulated, and based on the acquired terminal information, the first NW communication terminal capable of communicating with the communication partner first NW communication terminal A second location information holding means for holding the location information of the second NW communication device capable of grasping the 2NW communication device and communicating with the first NW communication terminal of the communication partner; Based on the position information holding means, the position information of the second NW communication device capable of communicating with the first NW communication terminal of the communication partner, and the own position information, between the first NW communication terminal of the communication partner and itself A distance calculation means for calculating the distance of the wireless communication device and a wireless transmission power for communicating with the first NW communication terminal of the communication partner via the first network based on the distance calculated by the distance calculation means. Communication system further comprising a transmission power determining unit.

In the second aspect of the present invention, there are a plurality of first NW communication terminals belonging to the first network, and a plurality of second NW communication devices belonging to the second network. A first communication processing unit for communicating wirelessly with the first NW communication terminal via the first network, and a second communication processing unit for performing wireless communication with a second NW communication device, Each of the 2NW communication devices is a communication method in a communication system having a narrow coverage area capable of wireless communication than the first communication processing unit of the first NW communication terminal, and includes a terminal information holding unit, a storage unit, and a first location information Holding terminal, second position information holding means, distance calculating means, and transmission power determining means, wherein the terminal information holding means is a first NW communication capable of communicating with itself in each second NW communication device. Terminal information relating to the terminal, and the storage means collects and stores terminal information held by other second NW communication apparatuses in each second NW communication apparatus, and the first position information holding means includes: In each first NW communication terminal, when trying to start communication with another first NW communication terminal, the terminal information accumulated by the second NW communication device capable of communicating with itself is acquired, and based on the acquired terminal information, The second NW communication device that can communicate with the first NW communication terminal that is the communication partner is grasped, and the position information of the second NW communication device that can communicate with the first NW communication terminal that is the communication partner is retained, and the second position information The holding means holds its own position information in each first NW communication terminal, and the distance calculation means uses the first NW communication terminal of the communication partner in each first NW communication terminal. Based on the position information of the communicable second NW communication device and its own position information, the distance between the first NW communication terminal of the communication partner and itself is calculated. The first NW communication terminal determines wireless transmission power for communication with the first NW communication terminal of the communication partner via the first network based on the distance calculated by the distance calculation means. Communication method.

  In the present invention, power consumption can be saved as compared with the prior art.

(A) Embodiment Hereinafter, an embodiment will be described with reference to an example in which the communication system and method according to the present invention are applied to a mobile communication system.

(A-1) Configuration of First Embodiment FIG. 1 shows an example of the overall configuration of a mobile communication system 9 according to the present embodiment.

  In FIG. 1, the mobile communication system 9 includes a sensor network 10 and a wireless LAN network 20. The sensor network 10 includes sensor nodes 11 to 14, and the wireless LAN network 20 includes mobile terminals 21 to 22.

  Among these, the sensor network 10 is a characteristic infrastructure in the present embodiment, and has functions of collecting, transmitting, and storing control information, which will be described in detail later. The number of sensor nodes included in the sensor network 10 may be less than or greater than the four illustrated. Although the size of the physical spread of the sensor network 10 depends on the implementation, as an example, the sensor network 10 may have a limited range E1 with a radius of about 10 meters. An area E2 shown in FIG. 1 is a combination of wireless communication areas (cover areas) covered by any sensor node (for example, 12) in the sensor network 10. The area E2 is substantially equal to the range E1, and is also approximately equal to the range indicating the physical spread of the wireless LAN network 20.

  The important point is that the sensor nodes are distributed at a sufficiently high density within the range E1, and the same wireless LAN network (on average) from the viewpoint of any portable terminal (for example, 22) in the wireless LAN network 20 is important. That is, it is possible to acquire a distance relationship in which the distance to any one of the sensor nodes (for example, 12) in the sensor network 10 is closer than the distance to the other portable terminal (for example, 21) in the area 20. This facilitates saving power consumption on the mobile terminal (for example, 22) side.

  Communication between the sensor node (for example, 12) and the portable terminal (for example, 22) is performed wirelessly, but communication between the sensor nodes (for example, between 12 and 13) can also be performed by wire. However, here, communication between sensor nodes is also performed wirelessly. The power consumed by the sensor node may be constantly supplied from a commercial power source or the like using power supply wiring, but here, the power is supplied from the battery loaded in each sensor node. The configuration is obtained.

  When taking such a configuration, if each sensor node is created as an extremely small-sized device, for example, the sensor network 10 can be constructed very simply by simply attaching a plurality of sensor nodes to the ceiling or floor of the building. There are advantages.

  The sensor node (for example, 12) may repeatedly transmit a predetermined beacon frame, for example, in order to convey its presence to the sensor unit of the mobile terminal. The beacon frame is repeatedly transmitted regardless of whether or not the mobile terminal exists in the cover area of the sensor node, and when the mobile terminal (for example, 22) moves into the cover area, the mobile terminal The sensor unit (for example, 22A) of the terminal recognizes the presence of the sensor node by receiving the beacon frame. This is equivalent to recognizing that it entered the area E2.

  When such a beacon frame is not used, in order for the mobile terminal and the sensor node to communicate, for example, the user (for example, U2) recognizes that he / she has entered the area E2, and expresses that fact explicitly. It is necessary to tell the terminal (for example, 22). In any case, while the sensor unit recognizes that it exists in the area E2, the sensor unit repeats an operation of transmitting control information described later.

  An example of the internal configuration of the sensor node 12 is shown in FIG. Since all the internal configurations of the sensor nodes 11 to 14 may be the same, the internal configurations of the other sensor nodes (for example, 13) are also the same as the sensor node 12.

(A-1-1) Internal Configuration Example of Sensor Node In FIG. 9, the sensor node 12 includes a control unit 30, a terminal information storage unit 31, a distance calculation unit 32, and a radio unit 33.

  The control unit 30 controls the components 31 to 33 in the sensor node 12 and corresponds to a CPU (central processing unit) in terms of hardware and an OS (operating system) in terms of software. obtain.

  The terminal information storage unit 31 is a part that stores control information transmitted from a mobile terminal located within the cover area of the sensor node 12 and control information transmitted from another sensor node (for example, 13). .

  The wireless unit 33 is a part that performs wireless communication, and corresponds to the sensor unit 22A illustrated in FIG. The counterpart of wireless communication by the wireless unit 33 may be another sensor node (for example, 13) in the sensor network 11 or a sensor unit (for example, 22A) of the mobile terminal.

  The distance calculation unit 32 is a part that calculates the distance between nodes based on the strength of radio waves (reception strength) received by the radio unit 33. As will be described later, this distance calculation unit 32 may be omitted depending on how the distance is obtained.

  A portable terminal (for example, 22) that performs wireless communication with such a sensor node (for example, 12) has a communication function as a node in the wireless LAN network 20, that is, a communication protocol (for example, IEEE802.11b) corresponding to the wireless LAN. Etc. (including transmission medium access control schemes such as CSMA / CA)), in addition, it has a function of performing wireless communication with the sensor node. Specifically, for example, a notebook personal computer or a PDA may correspond to the portable terminal.

  An example of the internal configuration of the mobile terminal 22 is shown in FIG. The internal configuration of the other mobile terminal 21 is the same as that of the mobile terminal 22. The portable terminal 22 is carried and used by the user U2, and the portable terminal 21 is carried and used by the user U1.

(A-1-2) Internal configuration example of portable terminal
In FIG. 10, the portable terminal 22 includes a control unit 40, a terminal information storage unit 41, a distance measurement unit 42, a wireless unit 43, a connection I / F unit 44, a power supply unit 45, and a wireless LAN unit 46. And.

  Since the control unit 40 corresponds to the control unit 30 and the terminal information storage unit 41 corresponds to the terminal information storage unit 31, detailed description thereof is omitted.

  However, the control unit 40 must also have a function of controlling the transition to the power saving mode related to the wireless LAN unit 46.

  The power saving mode is a mode in which the wireless LAN unit 46 performs only reception without transmitting packets. By shifting the wireless LAN unit 46 to the power saving mode, power consumption in the wireless LAN unit 21 can be saved as compared with the normal mode in which packets are received and transmitted.

The communication partner of the wireless unit 43 is a sensor node (here, 12) corresponding to the cover area where the mobile terminal 22 is currently located. The distance measuring unit 42 receives the reception intensity obtained by the distance calculating unit 32. This is a part for calculating the distance to the mobile terminal as the communication partner based on However, as will be described later, the mobile terminal can determine the distance to the mobile terminal that is the communication partner by other methods.

  The power supply unit 45 is a part that supplies power to the components 40 to 44 and 46 in the mobile terminal 22. In the case of a portable terminal, the loaded battery is the main body of the power supply unit 45.

The wireless LAN unit 46 is a part that basically executes processing corresponding to a normal wireless LAN communication protocol (for example, the IEEE802.11b). In the present embodiment, the wireless LAN unit 46 corresponds to the power saving mode. It is also necessary to provide functions. The power supply unit 45 and the wireless LAN unit 46 corresponding to the wireless LAN unit 22B shown in FIG. 1 are constituent elements that are always included in the communication terminal corresponding to the wireless LAN. 40 and these are connected by a connection I / F unit 44.

  Hereinafter, the operation of the present embodiment having the above configuration will be described with reference to the flowcharts of FIGS. The flowchart of FIG. 2 shows a registration operation for registering control information related to the mobile terminal in the sensor network 10, and is composed of steps S1 to S3. The flowchart of FIG. 3 shows an operation when the mobile terminal communicates with other mobile terminals in the wireless LAN network 20, and includes steps S10 to S14.

  FIG. 11 is a sequence diagram summarizing the registration operation shown in FIG. 2 from another viewpoint. FIG. 11 includes steps S50 to S53 and S60 to S63.

  Further, the sequence shown in FIG. 12 is a summary of the operations shown in FIG. 3 from another viewpoint. FIG. 12 includes steps S69 to S83.

(A-2) Operation of the First Embodiment Here, the operation will be described by paying attention to the mobile terminal 22 that is one of the mobile terminals included in the wireless LAN network 20. The portable terminal 22 is carried by the user U2 and is located in the area E2.

  When the user U2 is not particularly communicating within the wireless LAN network 20, the mobile terminal 22 is operating in the power saving mode (a mode in which only packet reception is performed) (S1). In the power saving mode, the mobile terminal 22 does not transmit a control packet to another mobile terminal (for example, 21), but repeatedly controls the sensor nodes in the sensor network 10 periodically or irregularly. Sending information.

  The transmission power for transmitting the control information may be a value that can accurately deliver the control information to at least one sensor node (for example, 12) in the sensor network 10. In other words, when designing and constructing the sensor network 10, if at least one of the sensor nodes can receive the control information transmitted from the mobile terminal from any position within the area E2, The value of the transmission power may be a constant value.

  However, in practical terms, within a very limited range, even if there is a position where the control information cannot be accurately delivered to any sensor node in the area E1, it does not cause a significant problem. Probability is high. If it is recognized that communication cannot be performed normally, the user (for example, U2) only needs to move to a position where communication can be performed normally.

  In the state shown in FIG. 1, the sensor node 12 is closest to the mobile terminal 22 (ie, adjacent to the mobile terminal 22), and the distance is LG2. It is almost sufficient if the portable terminal 22 is configured (or set) so as to transmit the control information to a communication partner separated by the distance LG2 with transmission power capable of accurately delivering the control information.

  In step S2 following step S1, the mobile terminal 22 registers the control information with respect to an adjacent sensor node (here, 12) by transmitting the control information with the transmission power. Here, the mobile terminal 22 may transmit the control information after recognizing that the partner to which the control information is delivered is not the other sensor node but the sensor node 12, but this is not always necessary in the present embodiment. . The portable terminal 22 simply repeats the operation of transmitting control information with a predetermined transmission power (without distinguishing individual sensor nodes).

  Although various information may be included in the control information, in this embodiment, it is assumed that identification information that can uniquely specify the mobile terminal 22 in the mobile communication system 9 is included. There is a possibility that various kinds of identification information can be used. For example, a MAC address or an IP address can be used. For example, since the MAC address is unique identification information in a global range, it is naturally unique within the mobile communication system 9.

  Here, the identification information for designating the portable terminal 22 is MC22, and the identification information for designating the portable terminal 21 is MC21.

  Similarly, the identification information is also given to each of the sensor nodes 11 to 14, the identification information of the sensor node 11 is MC11, the identification information of the sensor node 12 is MC12, the identification information of the sensor node 13 is MC13, and the sensor node 14 The identification information is MC14.

  In step S2, when the control information (identification information MC22) is wirelessly transmitted from the portable terminal 22 in a protocol data unit (here, referred to as a frame) CP22 corresponding to a predetermined communication protocol, transmission power and In the case of FIG. 1, only the sensor node 12 can correctly receive the frame CP22 in the case of FIG.

  In step S2, the sensor node 12 also stores (registers) in the terminal information storage unit 31 that the frame CP22 has been received from the node of the identification information MC22 (that is, the mobile terminal 22).

  Next, the sensor node 12 broadcasts a frame CP12 including a set of its own identification information MC12 and the identification information MC22 to other sensor nodes in the sensor network 10 (S3).

  The broadcasted frame (here, CP12) is a frame that is destined for all unspecified sensor nodes. Therefore, all the sensor nodes that exist within a range where wireless communication can be performed with the sensor node (here, 12). The frame is received, and the set contained in the frame is registered. For example, in the case of FIG. 1, the sensor nodes 11 and 13 correspond to sensor nodes that are within a distance that allows wireless communication with the sensor node 12.

  Note that the group included in the frame CP12 is information specifying a sensor node adjacent to the mobile terminal 22 (that is, position information indicating the position of the mobile terminal).

  Based on this set, other sensor nodes (for example, 13) in the sensor network 10 can specify that the mobile terminal 22 is currently located in the cover area covered by the sensor node 12. Further, the sensor node 12 itself can recognize that there is a portable terminal having the corresponding identification information in its own cover area based on the information (identification information MC22) registered in step S3.

  The broadcast may be repeated a plurality of times, but in this embodiment, the maximum value of the distance to the destination with which the mobile terminal communicates in the wireless LAN network 20 is smaller than in the second embodiment described later. The number of times may be small (for example, about once). When the number of broadcasts is limited to one, the set of information transmitted in the frame CP12 does not reach the sensor node 14 shown in FIG. When the number of sensor nodes in the sensor network 10 is much larger than the four shown in FIG. 1, it is natural that the number of broadcasts may be limited to a plurality of times (for example, 3 times).

  As shown in FIG. 11, the other mobile terminals (for example, 21) in the wireless LAN network 20 also execute the registration operation similar to that in FIG. 2 in parallel at the same time.

  As a result of each mobile terminal performing the registration operation and the set of information corresponding to the registration operation being broadcast in the sensor network 10, when viewed from a certain mobile terminal (22 in this case), a sensor node ( Here, in 12), information of a set of mobile terminals located within a distance that allows communication with itself in the wireless LAN network 20 (that is, position information) is accumulated.

  On the other hand, the operation when the mobile terminal 22 communicates with other mobile terminals in the wireless LAN network 20 is as follows.

  In FIG. 3, the user U2 carrying the portable terminal 22 activates some communication application installed in the portable terminal 22 and designates that the other party who wants to communicate with the communication application is the portable terminal 21 ( For example, when designated by a MAC address or the like, the portable terminal 22 acquires position information of the portable terminal 22 from an adjacent sensor node (here, 12) (S11).

  Thereafter, the mobile terminal 22 obtains a distance from the mobile terminal 21 (S12).

  When the position information is the above-described group and the distance is obtained based only on the group, the detailed distance is not known, but the distance to the sensor node is obtained based on the distance calculated by the distance calculator 32. be able to. The distance to the sensor node (for example, 13) is substantially equal to the distance to the mobile terminal (for example, 21) located in the cover area of the sensor node.

  However, it is possible to use other methods as the method for obtaining the distance. When the distance to the communication partner is obtained without using the distance calculated by the distance calculator 32, the distance calculator 32 is used. Can be omitted.

  For example, if the arrangement interval of each sensor node is set to the same distance (node arrangement interval), the sensor node is located within the coverage area of the sensor node within the range that can be reached by one broadcast. It can be seen that the distance is approximately the distance of the node arrangement interval.

  Further, when the sensor nodes 11 to 14 are installed and the sensor network 10 is constructed, the distance from each sensor node to another sensor node is registered in each sensor node. In step S11, Instead of the identification information (for example, identification information MC13 of the sensor node 13) constituting the set as the position information, the distance to the sensor node may be transmitted to the mobile terminal 21.

  Or when measuring the exact position of each portable terminal by a method utilizing an external system such as GPS (Global Positioning Systems) and registering the measurement result as the position information, the portable terminal 22 It is also possible to calculate an accurate distance to the partner mobile terminal 21 from the accurate position of the mobile terminal 21 and its own accurate position.

  In any case, in step S12, the distance to the mobile terminal 21 that is the communication partner can be obtained. In subsequent step S13, communication with the mobile terminal 21 is performed in the wireless LAN network 20 based on the distance. The minimum transmission power (minimum transmission power) necessary for this is obtained, and the value of the transmission power is transmitted to the wireless LAN unit 46 in the portable terminal 22 (S13).

  At this time, the control unit 40 of the mobile terminal 22 cancels the power saving mode of the wireless LAN unit 46, and wirelessly transmits the packet addressed to the mobile terminal 21 of the communication partner with the transmission power (S14). Since the transmission power is not unnecessarily large, the power consumption of the mobile terminal 22 is suppressed to the minimum, and the range in which radio wave interference occurs is narrow, so that other mobile terminals (not shown) in the wireless LAN network 20 There is little possibility of hindering communication between them, and the utilization efficiency of frequency resources can be increased.

  When this packet arrives, the mobile terminal 21 of the communication partner is in the power saving mode, but the receiving operation can be performed even in the power saving mode. If this communication is a one-way communication, it may be left as it is. However, if two-way communication is required, the portable terminal 21 cancels the power saving mode after receiving the packet, and the portable terminal 22 The packet addressed to is transmitted. Even in the transmission of this packet, it is a matter of course that the transmission power can be controlled to the minimum by obtaining the position information of the partner mobile terminal from the adjacent sensor node (13 for 21).

  When the communication is completed, the wireless LAN unit 46 of any portable terminal (22 and 21 here) enters the power saving mode (S15).

  In the sequence diagram of FIG. 12, it is necessary from the sensor node (for example, 13) that stores the control information by the search request and the response corresponding to the search request in the sensor network 10 instead of the broadcast. To a sensor node (for example, 12).

  In this case, the search request sent from the sensor node 12 to the sensor node 13 is a search request (S70) received by the sensor node 12 from the mobile terminal 22 after the mobile terminal 22 activates its own wireless unit 43 (S69). The control information obtained as a response to the search request is finally delivered to the mobile terminal 22 via the sensor node 12.

(A-3) Effect of First Embodiment According to the present embodiment, since the mobile terminals (21, 22) can be controlled via the sensor network (10), the wireless LAN network (20) Therefore, it is almost unnecessary to transmit a control packet, and power consumption in each portable terminal can be saved.

  In the present embodiment, the transmission power of the transmission source portable terminal is controlled to the minimum according to the distance to the destination portable terminal in communication within the wireless LAN network. It is possible to save power.

(B) Second Embodiment Hereinafter, only differences between the present embodiment and the first embodiment will be described.

  Considering the entire wireless LAN network, the remaining power amount of the battery of each mobile terminal is usually different, so it is necessary to consider the power consumption of the mobile terminal where communication is concentrated. For example, a mobile terminal that is often located near the center in an ad hoc network often provides a relay processing function described later for communication between other mobile terminals in a stochastic manner. In other words, there is a high possibility that power consumption will proceed more rapidly than other mobile terminals.

  In this case, since the user of the mobile terminal runs out of battery for the communication of the user of the other mobile terminal and cannot perform his own communication, the fairness and convenience are remarkably reduced.

(B-1) Configuration and Operation of Second Embodiment FIG. 4 shows an example of the overall configuration of the mobile communication system 9 of the present embodiment.

  In FIG. 4, since the functions of the constituent elements to which the same reference numerals 10, 11 to 14, 20, 21, 22, E1, and E2 as in FIG. To do.

  However, in this embodiment, each portable terminal 21, 22, 23, 24 is a node that is a constituent element of a so-called ad hoc network, and can support multi-hop communication. Therefore, in the communication within the wireless LAN network 20, the mobile terminal not only becomes a transmission source or destination, but also has a function of executing relay processing between other mobile terminals (relay processing function). Yes.

  For example, since the distance between the mobile terminals 22 and 21 is long, even when the packet cannot be wirelessly transmitted directly from the mobile terminal 22 to the mobile terminal 21, the mobile terminal 23 or 24 located in the middle is relayed. By using the processing function, the packet transmitted from the mobile terminal 22 can be delivered to the destination mobile terminal 21.

  Of course, since the positional relationship of each portable terminal in the area E2 varies with movement, it is natural that the portable terminals that provide the relay processing function for other portable terminals also vary. Here, the portable terminal 23 is carried and used by the user U3, and the portable terminal 24 is carried and used by the user U4.

  Note that as long as multi-hop communication is performed, the physical size of the areas E1 and E2 is also likely to be much larger in the present embodiment than in the first embodiment.

  The higher the transmission power, the farther the radio waves reach. However, increasing the transmission power causes problems such as increased power consumption and reduced use efficiency of frequency resources due to expansion of the range where radio interference occurs. In practice, there is a certain upper limit on the magnitude of transmission power. If multi-hop communication is used, it is possible to communicate with a farther mobile terminal even under such upper limit constraints.

  The operation of this embodiment is as shown in the flowcharts of FIGS.

The flowchart of FIG. 5 shows a registration operation for registering the control information related to the portable terminal in the sensor network 10, and includes the steps S21 to S23. The flowchart of FIG. 6 shows an operation when the mobile terminal communicates with other mobile terminals in the wireless LAN network 20, and includes steps S31 to S35.
In the flowchart of FIG. 5, step S21 corresponds to step S1, step S22 corresponds to step S2, and step S23 corresponds to step S3. Therefore, detailed description thereof is omitted.

  However, the control information registered by the mobile terminals 21 to 24 in the sensor network 10 in the present embodiment indicates the remaining power amount of the battery in each mobile terminal in addition to the identification information (position information) specifying each mobile terminal. Information (remaining battery information) is included.

  In the case of the present embodiment, it is natural that the power supply unit 45 in the mobile terminal shown in FIG. 10 needs to have a function of detecting the remaining power amount of the battery.

  Note that the wireless LAN network 20 of the present embodiment may include a mobile terminal having the relay processing function and a mobile terminal not having the relay processing function, but the battery remaining amount information in the present embodiment is a relay process. Since the function is used as an index indicating the remaining capacity to provide for other portable terminals, the portable terminal that does not have the relay processing function does not need to provide the remaining battery level information as part of the control information.

  In addition, the step S3 basically has to broadcast a frame (for example, CP12) only once, but in the step S23, it is highly necessary to repeat the broadcast a plurality of times. This is because only one broadcast cannot cover the entire range (all nodes) of the areas E1 and E2 whose physical size is larger than that of the first embodiment.

 On the other hand, in the flowchart of FIG. 6, Step S31 corresponds to Step S11, Step S32 corresponds to Step S12, Step S34 corresponds to Step S14, and Step S35 corresponds to Step S15. Detailed description is omitted.

  However, in the present embodiment, as described above, since the remaining battery level information is included in the control information, in step S31, the mobile terminal 22 that is the transmission source of the packet starts from the adjacent sensor node (here, 11). The acquired control information includes battery remaining amount information. Furthermore, since the number of frame broadcasts in the sensor network 10 has increased to cover all sensor nodes, the control information acquired by the mobile terminal 22 in step S31 also relates to all mobile terminals in the wireless LAN network 20. .

  Here, the mobile terminals 21 to 24 are in the positional relationship as shown in FIG. 4, and a case where a packet is transmitted from the mobile terminal 22 to the mobile terminal 21 is taken as an example. Since the distance between the mobile terminals 22 and 21 is long, the mobile terminal 22 uses one of the relay processing functions of the mobile terminals 23 and 24 to deliver the packet to the destination mobile terminal 21.

  Next, the portable terminal 22 obtains the shortest route based on the control information (S32). Whether it is the shortest or not is easy to judge based on the number of mobile terminals on the route (the number of hops), but if necessary, a judgment reflecting the physical transmission distance may be made. In this case, for example, when the number of hops is the same, a route having a short transmission distance can be made the shortest.

  When determining based on the number of hops alone, the route from the mobile terminal 23 to the destination mobile terminal 21 is the same as the route from the mobile terminal 24 to the destination mobile terminal 21 (hop number 2). Therefore, in step S32, both are the shortest paths.

  At this time, the remaining battery information in the control information related to the portable terminal 23 indicates that the amount of power remaining in the battery is less than a predetermined value, and the remaining battery information in the control information related to the portable terminal 24 is Mobile terminal 22 bypasses portable terminal 23 having no sufficient power, and passes a route through portable terminal 24 having sufficient power. Select (S33).

  Note that in order to perform multi-hop communication as in the present embodiment, there is a high possibility that information for route control needs to be exchanged between mobile terminals on the route. Is also handled as part of the control information and can be exchanged via the sensor network 10.

  After step S33, the steps S34 and S35 are sequentially executed.

(B-2) Effect of Second Embodiment According to the present embodiment, since the mobile terminals (21 to 24) can be controlled via the sensor network (10), the wireless LAN network (20) Therefore, it is almost unnecessary to transmit a control packet, and power consumption in each portable terminal can be saved.

  Further, in the present embodiment, since it is possible to perform route control in consideration of the remaining battery power of a mobile terminal (for example, 23, 24) that provides a relay processing function, fairness and convenience are high.

(C) Third Embodiment Hereinafter, only the points of this embodiment different from the first and second embodiments will be described.

  The portable terminal in this embodiment is different from the first and second embodiments in that it has a power-off mode in addition to the power saving mode.

(C-1) Configuration and Operation of Third Embodiment FIG. 7 shows an example of the overall configuration of the mobile communication system 9 of the present embodiment.

  In FIG. 7, the function of each component given the same reference numerals 10, 11 to 14, 20, 21, 22, E1, and E2 as in FIG. 1 is basically the same as in the first embodiment, and detailed description thereof is omitted. To do.

  However, in this embodiment, each portable terminal 21, 22, 25 has a power-off mode in addition to the power saving mode described above.

  In the power saving mode, the wireless LAN unit 46 of each portable terminal (for example, 22) can execute only reception, but in the power-off mode, transmission and reception cannot be performed. Therefore, the power consumed by the wireless LAN unit 46 is less in the power-off mode than in the power saving mode. In the power-off mode, the power consumption in the wireless LAN unit 46 is almost zero.

  While in the power-off mode, various modifications can be considered as to whether or not the components other than the wireless LAN unit 46 of the portable terminal (for example, 22) operate and power is consumed, but at least the sensor unit (For example, 22A) needs to operate effectively.

  The mode transition of each portable terminal (for example, 25) is changed to the power saving mode when communication from another portable terminal (for example, 22) in the wireless LAN network 20 has not been performed for a certain time (power saving transition time) or longer. When the transition is made and the transition to the power saving mode has not been performed for a certain time (power-off transition time) or longer, the power-off mode is entered. How to set the power saving transition time and the power-off transition time is arbitrary, and it is not always necessary to set both to the same time. However, both may be set to about several seconds as an example.

  In addition, the portable terminal 25 in FIG. 7 is carried by the user U5 and used.

  The operation of this embodiment is as shown in the flowchart of FIG. The flowchart in FIG. 8 includes steps S41 to S49.

  In FIG. 8, step S42 corresponds to step S2, step S43 corresponds to step S23, and step S48 corresponds to step S34. Therefore, detailed description thereof is omitted.

  Here, the operation will be described by taking as an example a case where the mobile terminal 25 that has moved from the outside of the wireless LAN network 20 communicates with the mobile terminal 24 in the wireless LAN network 20. Until then, since the portable terminal 25 was located outside the area E2, control information regarding the portable terminal 25 is not registered in any of the sensor nodes 11-14.

  In FIG. 8, it is assumed that the mobile terminal 22 is initially in the power-off mode (S41). At this time, the portable terminal 25 moves together with the user U5 from the outside of the area E2.

  The sensor unit 25 of the mobile terminal 25 can recognize that it has entered the cover area of the sensor node (here, 11), for example, by receiving the beacon frame, and send a packet including its own control information. It transmits to the sensor node and registers (S42).

  Subsequently, the control information of the portable terminal 25 is transmitted to the other sensor nodes in the sensor network 10 by the broadcast in step S43. In step S44, the portable terminal 25 is located nearby from the adjacent sensor node 11 (see FIG. In the example of 7, the control information related to 22) is read. Thereby, the said portable terminal 25 detects this portable terminal 22 as an adjacent terminal (S45).

  For example, a mobile terminal located within the cover area of a sensor node (here, 12) located 1 hop away from the adjacent sensor node 11 may be an adjacent terminal.

  However, Steps S44 to S45 and Steps S46 to S49 described later are executed when the user U5 of the portable terminal 25 desires communication, and when the user U5 does not desire communication, Steps S41 to S43 are performed. Although executed, steps S44 to S49 are not executed.

  Here, it is assumed that the user U5 desires communication.

  The communication partner (the destination of the packet to be transmitted) that the user U5 desires to communicate is not necessarily the adjacent terminal (22), but the communication partner is a portable terminal other than the adjacent terminal (for example, 21). In this case, since it is necessary to use the relay processing function of the adjacent terminal, communication with the adjacent terminal occurs in any case. Here, for simplicity, it is assumed that the communication partner of the mobile terminal 25 is the adjacent terminal 22.

  When the portable terminal 25 transmits control information (communication start request signal) for requesting the start of communication with the adjacent terminal 22 from the sensor unit 25A, the communication start request signal is passed through the sensor nodes 11 and 12 to the adjacent terminal. It is delivered to 22 sensor units 22A (S46). At this time, since the wireless LAN unit 22B of the adjacent terminal 22 cannot receive in the power-off mode, the communication start request signal needs to be delivered to the sensor unit 22A of the adjacent terminal 22 via the sensor network 10. is there.

  The adjacent terminal 22 that has received the communication start request signal via the sensor unit 22A supplies power to the wireless LAN unit 22B and transitions to the normal mode, thereby enabling communication within the wireless LAN network 20 ( In step S47, the packet transmitted from the wireless LAN unit 25B by the mobile terminal 25 is actually received by the wireless LAN unit 22B (S48). At this time, it is natural that the packet may be transmitted from the wireless LAN unit 25B to the wireless LAN unit 22B as necessary.

  The wireless LAN units 25B and 22B of the mobile terminals 25 and 22 transition to the power saving mode when the power saving transition time elapses after the end of the communication, and further change to the power interruption mode when the power interruption transition time elapses. (S49).

  When the control information (communication end signal) that explicitly notifies the end of communication is delivered from the mobile terminal 25 to the adjacent terminal 22 or from the adjacent terminal 22 to the mobile terminal 25, each mobile terminal 22, The 25 wireless LAN units 22B and 25B may immediately transition to the power-off mode. This communication end signal can be transmitted by communication within the wireless LAN network 20 or by communication via the sensor network 10.

(C-2) Effects of the Third Embodiment According to the present embodiment, since the mobile terminals (21 to 24) can be controlled via the sensor network (10), the wireless LAN network (20) Therefore, it is almost unnecessary to transmit a control packet, and power consumption in each portable terminal can be saved.

  In the present embodiment, since the power-off mode is provided that consumes less power in the wireless LAN unit (for example, 22B) than in the power saving mode, it is possible to further save power consumption.

(D) Other Embodiments The features of the first to third embodiments can be combined in various combinations as long as they do not contradict each other.

  For example, when the features of the first embodiment and the features of the second embodiment are combined, limiting the transmission power of the mobile terminal to the minimum is only between the source mobile terminal and the destination mobile terminal. In addition, transmission between a mobile terminal that is a transmission source and a mobile terminal that provides a relay processing function, or between a plurality of mobile terminals that provide a relay processing function (when the number of hops from the transmission source to the destination is 3 or more) It can also be executed for transmission power.

  Moreover, although the portable terminal of the said 1st-3rd embodiment was a communication terminal which has high mobility, such as a notebook personal computer and PDA, this invention is also a communication terminal which does not have high mobility. Applicable.

  For example, the present invention can be applied to a case in which a wireless LAN card is mounted even in a stationary personal computer. Even a stationary personal computer may be newly added to the wireless LAN network, or a personal computer that previously existed may be deleted from the wireless LAN network. It is because it can be seen that it is almost equivalent to what has been done.

  The wireless LAN network 20 can be replaced with a wireless communication network other than the wireless LAN.

  In the above description, most of the functions realized in hardware can be realized in software, and almost all the functions realized in software can be realized in hardware.

1 is a schematic diagram showing an example of the overall configuration of a mobile communication system according to a first embodiment. It is operation | movement explanatory drawing of 1st Embodiment. It is operation | movement explanatory drawing of 1st Embodiment. It is the schematic which shows the example of whole structure of the mobile communication system concerning 2nd Embodiment. It is operation | movement explanatory drawing of 2nd Embodiment. It is operation | movement explanatory drawing of 2nd Embodiment. It is the schematic which shows the example of whole structure of the mobile communication system concerning 3rd Embodiment. It is operation | movement explanatory drawing of 3rd Embodiment. It is the schematic which shows the structural example of the principal part of the sensor node used with the mobile communication system concerning the 1st-3rd embodiment. It is the schematic which shows the structural example of the principal part of the portable terminal used with the mobile communication system concerning the 1st-3rd embodiment. It is operation | movement explanatory drawing of 1st Embodiment. It is operation | movement explanatory drawing of 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 9 ... Mobile communication system, 10 ... Sensor network, 20 ... Wireless LAN network, 11-14 ... Sensor node, 21, 22 ... Portable terminal, 21A, 22A ... Sensor part, 21B, 22B ... Wireless LAN part.

Claims (4)

  In a communication system having a plurality of first NW communication terminals belonging to a first network and a plurality of second NW communication devices belonging to a second network,
  Each of the first NW communication terminals includes a first communication processing unit for wirelessly communicating with another first NW communication terminal via the first network, and a second for wirelessly communicating with a second NW communication device. A communication processing unit,
  Each of the second NW communication devices is
    The cover area capable of wireless communication is narrower than the first communication processing unit of the first NW communication terminal,
    Terminal information holding means for holding terminal information related to the first NW communication terminal capable of communicating with itself;
    Storing means for collecting and storing terminal information held by other second NW communication devices,
  The first NW communication terminals are respectively
    When trying to start communication with another first NW communication terminal, the terminal information accumulated by the second NW communication device capable of communicating with itself is acquired, and based on the acquired terminal information, the communication with the first NW communication terminal of the communication partner First position information holding means for grasping a second NW communication apparatus capable of communicating and further holding position information of a second NW communication apparatus capable of communicating with the first NW communication terminal of the communication partner;
    Second position information holding means for holding its own position information;
    The distance for calculating the distance between the first NW communication terminal of the communication partner and itself based on the position information of the second NW communication device capable of communicating with the first NW communication terminal of the communication partner and the own position information A calculation means;
    Based on the distance calculated by the distance calculating means, further comprising transmission power determining means for determining wireless transmission power when communicating with the first NW communication terminal of the communication partner via the first network.
  A communication system characterized by the above. The communication system of claim 1.
The first NW communication terminal is
A relay processing unit that relays communication between other first NW communication terminals in the first network;
The terminal information, in which case the first 1NW includes relay capability information reflecting the execution capacity for relay processing in the communication terminal, the 1NW communication terminal which is to start communications in the first network is the relay Based on the capability information, the first NW communication terminal that is not suitable for the relay process is detected, a relay path that bypasses the first NW communication terminal that is not suitable for the relay process is set, and communication in the first network is executed. A communication system characterized by the above. The communication system of claim 1 .
In the case where the terminal information includes position designation information indicating whether each first NW communication terminal exists in at least one of the second NW communication devices in the cover area ,
The first NW communication terminal is
When a predetermined sleep condition is satisfied, the first communication processing unit performs a transition to a complete sleep mode in which communication within the first network is not performed including transmission and reception of control information; and
Examples terminal information, further comprising a communication start request unit that transmits a communication start request information that requests communication start together with the location specifying information to specify the first 1NW communication terminal of the destination to the 1NW communication terminal of the destination,
The second NW communication device is
Based on the position specifying information in the terminal information received, further comprising a position determining unit that determines whether the 1NW communication terminal of the destination is present in its coverage area,
When the position determination unit determines that the destination first NW communication terminal exists in its own cover area , the communication start request information is transmitted to cancel the complete sleep mode of the destination first NW communication terminal. A communication system.   A plurality of first NW communication terminals belonging to the first network and a plurality of second NW communication devices belonging to the second network;
  Each of the first NW communication terminals includes a first communication processing unit for wirelessly communicating with another first NW communication terminal via the first network, and a second for wirelessly communicating with a second NW communication device. A communication processing unit,
  Each of the second NW communication devices has a smaller coverage area capable of wireless communication than the first communication processing unit of the first NW communication terminal.
  A communication method in a communication system, comprising:
  Terminal information holding means, storage means, first position information holding means, second position information holding means, distance calculation means, transmission power determination means,
  The terminal information holding means holds terminal information related to the first NW communication terminal capable of communicating with itself in each second NW communication device,
  The storage means collects and stores terminal information held by other second NW communication devices in each second NW communication device,
  The first location information holding means obtains terminal information accumulated by a second NW communication device capable of communicating with itself when each first NW communication terminal tries to start communication with another first NW communication terminal. Then, based on the acquired terminal information, the second NW communication device that can communicate with the first NW communication terminal of the communication partner is grasped, and further, the position information of the second NW communication device that can communicate with the first NW communication terminal of the communication partner Hold
  The second position information holding means holds its own position information in each first NW communication terminal,
  The distance calculating means, in each first NW communication terminal, based on the position information of the second NW communication apparatus capable of communicating with the first NW communication terminal of the communication partner and the own position information, the first NW of the communication partner. Calculate the distance between the communication terminal and itself,
  In the first NW communication terminal, the transmission power determination means in the previous period is based on the distance calculated by the distance calculation means and communicates with the first NW communication terminal of the communication partner via the first network. Determine transmit power
  A communication method characterized by the above.

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