Patent Publication Number: US-2017359696-A1

Title: Communication method

Description:
TECHNICAL FIELD 
     The present invention relates to a wireless terminal (Peer-to-Peer (hereinafter, referred to as “P2P”) terminal) mutually wirelessly connectable by P2P, communication control method and program therefor, a communication method, and a communication system. 
     BACKGROUND ART 
     Over recent years, from the viewpoint of band widening, security enhancement, and the like, attention has been focused on Wi-Fi Direct as an inter-terminal communication method. A previous Wi-Fi network has been operated in an infrastructure mode in which a specific device is used as an access point (AP). On the other hand, a network conforming to Wi-Fi Direct allows any P2P terminal to become a Group Owner instead of a specific device, and thereby makes it possible to communicate in a group thereof (see NPL 1, for example). The Group Owner is a P2P terminal operating as an access point of a group and is capable of forming, as a parent of the group, a group including another P2P terminal as a child (client). 
     In the P2P group formed in this manner, it is possible to share data among terminals without connecting to the Internet or the like, and transfer data at high speed. In particular, in Wi-Fi Direct, a robust security protocol is supported and therefore higher security can be achieved compared to the security in a conventional ad hoc mode (IBSS: Independent Basic Service Set, or the like). 
     CITATION LIST 
     Non Patent Literature 
     
         
         NPL 1: Wi-Fi Alliance Technical Committee PSP Tack Group, Wi-Fi Peer-to-Peer (P2P) Technical Specification Version 1.1 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the above-described wireless P2P network, each group is independently formed and operated, and therefore data sharing is limited within the group. Further, in general, a maximum number of terminals of one group has a physical upper limit. When the above-described Wi-Fi Direct is built using an inexpensive wireless LAN device, for example, the number of units of the group is limited to an upper limit of approximately 5 to 10 units supported by the device. Such limitation to a group size limits sharing of messages to only terminals in one group and inhibits information sharing in a larger network including a plurality of groups. In the above-described wireless P2P network, it is not possible to report disaster information, traffic information, SOS signals and voice signals with emergency, and the like beyond a local group. 
     An object of the present invention is to provide a communication method, a communication system, a wireless terminal, communication control method and program therefor that solve the above-described problem, i.e., a problem in which information transmission between groups is difficult in a wireless P2P network. 
     Solution to Problem 
     A communication method according to one example embodiment of the present invention is 
     a communication method in a wireless communication network including a plurality of nodes each capable of performing wireless communication by a first communication method that can form a Peer-to-Peer group and wireless communication by a second communication method, wherein 
     a first owner node that operates as an access point of a first Peer-to-Peer group discovers a second Peer-to-Peer group present in a second communicable range that is a region outside a first communicable range defined by the first communication method using the wireless communication by the second communication method, predicts a time that elapses before the second Peer-to-Peer group moves into the first communicable range, and performs group reconfiguration before the predicted time elapses. 
     A communication system according to another example embodiment of the present invention is 
     a communication system in a wireless communication network including a plurality of nodes each capable of performing wireless communication by a first communication method that can form a Peer-to-Peer group and wireless communication by a second communication method, the system including: 
     a first Peer-to-Peer group including a first owner node that operates as an access point and a client node; and 
     a second Peer-to-Peer group including a second owner node that operates as an access point and a client node, wherein 
     the first owner node discovers the second Peer-to-Peer group present in a second communicable range that is a region outside a first communicable range defined by the first communication method using the wireless communication by the second communication method, predicts a time that elapses before the second Peer-to-Peer group moves into the first communicable range, and performs group reconfiguration before the predicted time elapses. 
     A wireless terminal according to another example embodiment of the present invention is 
     a wireless terminal including: 
     a first wireless communication unit by a first communication method that can form a Peer-to-Peer group with another wireless terminal; 
     a second wireless communication unit by a second communication method; and 
     an automatic connection control unit, wherein
         the automatic connection control unit includes a first function of discovering a second Peer-to-Peer group present in a second communicable range that is a region outside a first communicable range defined by the first wireless communication unit using the second wireless communication unit when operating as an access point of a first Peer-to-Peer group, a second function of predicting a time that elapses before the second Peer-to-Peer group moves into the first communicable range, and a third function of performing group reconfiguration before the predicted time elapses.       

     A communication control method of a wireless terminal according to another example embodiment of the present invention is 
     a communication control method of a wireless terminal including a first wireless communication unit by a first communication method that can form a Peer-to-Peer group with another wireless terminal and a second wireless communication unit by a second communication method, the communication control method including: 
     discovering a second Peer-to-Peer group present in a second communicable range that is a region outside a first communicable range defined by the first wireless communication unit using the second wireless communication unit when operating as an access point of a first Peer-to-Peer group; 
     predicting a time that elapses before the second Peer-to-Peer group moves into the first communicable range; and 
     performing group reconfiguration before the predicted time elapses. 
     A program according to another example embodiment of the present invention causes a computer to function as: 
     a first wireless communication unit by a first communication method that can form a Peer-to-Peer group with another wireless terminal; 
     a second wireless communication unit by a second communication method; and 
     an automatic connection control unit including a first function of discovering a second Peer-to-Peer group present in a second communicable range that is a region outside a first communicable range defined by the first wireless communication unit using the second wireless communication unit when operating as an access point of a first Peer-to-Peer group, a second function of predicting a time that elapses before the second Peer-to-Peer group moves into the first communicable range, and a third function of performing group reconfiguration before the predicted time elapses. 
     Advantageous Effects of Invention 
     The present invention includes the above-described configuration, and therefore is capable of transmitting information between a first and a second Peer-to-Peer group via a delivery node. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a communication system according to a first example embodiment of the present invention. 
         FIG. 2  is a flowchart illustrating an operation of the communication system according to the first example embodiment of the present invention. 
         FIG. 3  is a block diagram of a node (wireless terminal) configuring the communication system according to the first example embodiment of the present invention. 
         FIG. 4  is a diagram illustrating one example of a connection node list stored by the node configuring the communication system according to the first example embodiment of the present invention. 
         FIG. 5  is a diagram illustrating one example of group information stored by the node configuring the communication system according to the first example embodiment of the present invention. 
         FIG. 6  is a diagram illustrating one example of node information stored by the node configuring the communication system according to the first example embodiment of the present invention. 
         FIG. 7  is a diagram illustrating a connection flow of Wi-Fi Direct used in automatic connection by the communication system according to the first example embodiment of the present invention. 
         FIG. 8  is a diagram illustrating an operation flow of DEVICE DISCOVERY used in discovery of device by the communication system according to the first example embodiment of the present invention. 
         FIG. 9  is a diagram illustrating an operation flow of DEVICE DISCOVERY used in discovery of an existing group by the communication system according to the first example embodiment of the present invention. 
         FIG. 10  is a diagram illustrating an operation flow of GO NEGOTIATION used in automatic connection by the communication system according to the first example embodiment of the present invention. 
         FIG. 11  is a diagram illustrating an operation flow of PROVISION DISCOVERY used in automatic connection by the communication system according to the first example embodiment of the present invention. 
         FIG. 12  is a diagram illustrating an operation flow of INVITATION used in automatic connection by the communication system according to the first example embodiment of the present invention. 
         FIG. 13  is a diagram illustrating an operation flow of node disconnection used in automatic connection by the communication system according to the first example embodiment of the present invention. 
         FIG. 14  is a diagram illustrating an operation flow of nodes (wireless terminals) configuring the communication system according to the first example embodiment of the present invention. 
         FIG. 15  is an illustrative diagram of a method in which a GO node of a group of a side of sending a delivery node discovers another group and predicts a shortest time that elapses before the other group moves to a predetermined range in the first example embodiment of the present invention. 
         FIG. 16  is an illustrative diagram of a method in which a GO node of a group of a side of receiving a delivery node discovers another group and predicts a shortest time that elapses before the other group moves to a predetermined range in the first example embodiment of the present invention. 
         FIG. 17  is a block diagram of a communication system according to a second example embodiment of the present invention. 
         FIG. 18  is a flowchart illustrating an operation of the communication system according to the second example embodiment of the present invention. 
         FIG. 19  is a diagram visually illustrating an influence on information sharing by a delivery node caused by reconfiguration of a group in the second example embodiment of the present invention. 
         FIG. 20  is a diagram illustrating an operation flow of nodes (wireless terminals) configuring the communication system according to the second example embodiment of the present invention. 
         FIG. 21  a block diagram of a communication system according to a third example embodiment of the present invention. 
         FIG. 22  is a flowchart illustrating an operation of the communication system according to the third example embodiment of the present invention. 
         FIG. 23  is a diagram illustrating an operation flow of nodes (wireless terminals) configuring the communication system according to the third example embodiment of the present invention. 
         FIG. 24  is an illustrative diagram of an example embodiment that transmits/receives a position-information notification message among nodes via a server. 
         FIG. 25  is a diagram illustrating an example of predicting the presence or absence of a possibility in which a discovered group moves to a predetermined range and a shortest time that elapses before the movement thereto, using a curvature of a currently-running road. 
         FIG. 26  is a diagram illustrating an example of predicting the presence or absence of a possibility in which a discovered group moves to a predetermined range and a shortest time that elapses before the movement thereto, using a route estimated from a destination. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Next, example embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     First Example Embodiment 
     In the present example embodiment, one or a plurality of clients belonging to one group are disconnected as a delivery node and are connected to the other group to transfer information through the delivery node. Further, a range where one group can discover the other group by a Device Discovery procedure of the Wi-Fi Direct specification, i.e., a communicable range is narrow. Therefore, in a situation where groups configured by nodes mounted on moving bodies such as vehicles pass each other at high speed, even if a delivery node is immediately disconnected at the time when one group discovers the other group, the delivery node and the other group are separated far away from each other during the disconnection. Therefore, it is difficult to connect the delivery node to the other group. Further, when the other group that receives the delivery node already reaches an upper limit of the number of members, it is necessary to temporality disconnect an existing node in such a way that the delivery node can be connected. However, when such disconnection is started at the time when the other group enters a communicable range of the Wi-Fi Direct specification, the groups are separated far away from each other during the disconnection. Therefore, it becomes difficult to transfer information through the delivery node. It is also possible for the present example embodiment to solve such a problem. 
     Referring to  FIG. 1 , a communication system according to a first example embodiment of the present invention is configured by a plurality of nodes N 11  to N 21 . Each of the nodes N 11  to N 21  is a mobile wireless terminal mounted on a vehicle such as an automobile. Each of the nodes N 11  to N 21  is capable of performing wireless communication using a first communication method that can form a Peer-to-Peer group and wireless communication using a second communication method different therefrom. The first communication method is Wi-Fi Direct, for example, and the second communication method is cellular communication such as 3G and LTE, for example. Note that the first communication method is not limited to Wi-Fi Direct when being a communication method capable of forming a Peer-to-Peer group with another wireless terminal. Further, the second communication method is not limited to cellular communication when being a wireless communication method capable of performing longer-distance communication than the first communication method. 
     In  FIG. 1 , a plurality of nodes N 11  to N 21  configure two Peer-to-Peer groups G 1  and G 2  (hereinafter, simply referred to as group(s)) by the first communication method. The group G 1  is formed with the node N 11  as a parent (group owner), and the nodes N 12  to N 15  are children (clients) thereof. Further, the group G 2  is formed with the node N 16  as a group owner, and the nodes N 17  to N 21  are clients thereof. Still further, data D 1  and data D 2  are shared in the group G 1  and the group G 2 , respectively. Moreover, the nodes N 11  to N 15  of the group G 1  moving together in a direction indicated by an arrow A 1 , and the nodes N 16  to N 21  of the group G 2  are moving together in a direction indicated by an arrow A 2  opposite to the arrow A 1 . Such a situation appears when five vehicles mounted with the nodes N 11  to N 15  of the group G 1  are running in a column on a road, and six vehicles mounted with the nodes N 16  to N 21  of the group G 2  are running in a column on a traffic lane opposite to the road, for example. 
     Here, a maximum number of client nodes connectable to one group owner (hereinafter, referred to as a GO) is assumed to be five for description convenience. Under such limitation, five client nodes N 17  to N 21  are already connected to the GO node N 16  of the group G 2 , and therefore it is not possible for the GO node N 16  to have a new node to be connected thereto any more. 
       FIG. 2  is a flowchart illustrating an operation of the communication system according to the present example embodiment. With reference to  FIG. 2 , the following will describe operations for transferring shared information between a group G 1  and a group G 2  in the communication system according to the present example embodiment. In the present example embodiment, there is described an example in which the group G 1  whose number of members does not reach an upper limit operates as a group of a side of sending a delivery node, and the group G 2  whose number of members reaches an upper limit operates as a group of a side of receiving a delivery node. However, it is also possible to send a delivery node from both groups. 
     In a state where groups G 1  and G 2  are formed, when discovering a second group G 2  present outside a communicable range of the group G 1  defined by the first communication method, the GO node N 11  of the group G 1  of a side of sending a delivery node predicts a shortest time necessary for a GO node of the second group G 2  to move to a communicable range of a client of the group G 1  (step S 1 ). 
     Subsequently, before the predicted time elapses, the GO node N 11  of the group G 1  selects the client node N 15  of the group G 1  as a delivery node, instructs the selected delivery node to be connected to the group G 2 , and disconnects the delivery node from the group G 1  (step S 2 ). Here, one client node is designated as a delivery node, but a plurality of client nodes may be designated as delivery nodes. 
     On the other hand, when discovering a first group G 1  present outside a communicable range of the group G 2  defined by the first communication method, the GO node N 16  of the group G 2  of a side of receiving a delivery node predicts a shortest time necessary for a client node of the first group G 1  to move to a communicable range of the GO node of the group G 2  (step S 3 ). 
     Subsequently, before the predicted time elapses, the GO node N 16  of the group G 2  performs group reconfiguration in preparation for transferring information, through a delivery node, between the group G 1  and the group G 2 . Specifically, before the predicted time elapses, the GO node N 16  of the group G 2  temporarily disconnects, from the group G 2 , the client node N 21  already connected to the group G 2  and thereby reduces the number of connection clients, to allow the delivery node N 15  to be newly connectable (step S 4 ). Here, one client node is temporarily disconnected, but a plurality of client nodes may be temporarily disconnected. 
     In this manner, before the groups G 1  and G 2  approach each other at a communicable maximum distance or less defined by the first communication method, the group G 1  completes disconnection of a delivery node and the group G 2  keeps the number of connection members to be smaller than an upper limit. 
     Next, operations performed when the groups G 1  and G 2  approach each other at a communicable maximum distance or less defined by the first communication method will be described. 
     When discovering the GO node N 16  of the group G 2  by a Device Discovery procedure of the Wi-Fi Direct specification, for example, the delivery node N 15  disconnected from the group G 1  is connected to the GO node N 16 , and transfers shared information between the delivery node N 15  and the GO node N 16  (step S 5 ). Specifically, the delivery node N 15  transmits the data D 1  to the GO node N 16 , and the GO node N 16  transmits the data D 2  to the delivery node N 15 . Thereby, the GO node N 16  of the group G 2  can acquire the data D 1  shared in the group G 1 . Moreover, the data D 1  is transferred further to the client nodes N 17  to N 20  from the GO node N 16 , and thereby the client nodes N 17  to N 20  can acquire the data D 1  shared in the group G 1 . 
     Thereafter, the delivery node N 15  is disconnected from the group G 2  and is reconnected to the GO node N 11  of the group G 1 , and thereby transfers information between the delivery node N 15  and the GO node N 11  (step S 6 ). Specifically, the delivery node N 15  transmits the data D 2  to the GO node N 11 . Thereby, the GO node N 11  of the group G 1  can acquire the data D 2  shared in the group G 2 . Moreover, the data D 2  is transferred further to the client nodes N 12  to N 14  from the GO node N 11 , and thereby the client nodes N 12  to N 14  can acquire the data D 2  shared in the group G 2 . 
     On the other hand, when the delivery node N 15  is disconnected from the group G 2 , the client node N 21  temporarily disconnected from the group G 2  is reconnected to the GO node N 16  of the group G 2  (step S 7 ). Then, the data D 1  is transferred to the client node N 21  from the GO node N 16 , and thereby the client node N 21  can acquire the data D 1  shared in the group G 1 . 
     In this manner, shared information can be transmitted between the group G 1  and the group G 2  via the delivery node N 15 . 
     Further, before the groups G 1  and G 2  approach each other at the communicable maximum distance or less defined by the first communication method, the group G 1  completes disconnection of the delivery node N 15 , and the group G 2  completes disconnection of the client node N 21  to keep the number of connection members to be smaller than an upper limit. Therefore, in comparison with a case where the delivery node N 15  and the client node N 21  are disconnected within a time frame when the groups G 1  and G 2  approach each other at the communicable maximum distance or less defined by the first communication method, a time that can be used for connecting the delivery node N 15  to the group G 2  increases. Thereby, connection of the delivery node N 15  to the group G 2  can be prevented from failing due to a lack of time. 
     The following will describe a configuration and operation of the communication system according to the present example embodiment in more detail. 
       FIG. 3  is a block diagram illustrating a configuration example of a node N used as the nodes N 11  to N 21 . The node N in this example includes wireless communication interface units (hereinafter, referred to as wireless communication I/F units)  10  and  20 , an operation input unit  30 , a screen display unit  40 , a storage unit  50 , a processing unit  60 , and a GPS (Global Positioning System)  70 . 
     The wireless communication I/F units  10  and  20  each include a dedicated wireless communication circuit, and include a function of performing wireless communication with various types of devices such as other wireless terminals connected via a wireless communication line. Among these, the wireless communication I/F unit  10  is a wireless LAN interface corresponding to Wi-Fi Direct, and the wireless communication I/F unit  20  is a wireless interface corresponding to cellular communication such as 3G and LTE. 
     The operation input unit  30  includes an operation input device such as a keyboard and a mouse, and includes a function of detecting an operation of an operator and outputting the detected operation to the processing unit  60 . 
     The screen display unit  40  includes a screen display device such as an LCD (Liquid Crystal Display) and a PDP (Plasma Display Panel), and includes a function of screen-displaying various types of information such as an operation menu in accordance with an instruction from the processing unit  60 . 
     The GPS  70  measures a latitude x, a longitude y, and a height z indicating a current position of the node N, and includes a function of transmitting the measured values to the processing unit  60 . 
     The storage unit  50  includes a storage device such as a hard disk and a memory, and includes a function of storing processing information and a program  50 P necessary for various types of processing in the processing unit  60 . The program  50 P is a program for making various types of processing units by being read onto the processing unit  60  to be executed. The program  50 P is previously read from an external device (not illustrated) or a storage medium (not illustrated) via a data input/output function such as the communication I/F units  10  and  20 , or the operation input unit  30 , and is stored on the storage unit  50 . Main processing information stored on the storage unit  50  includes shared information  50 A, a connection node list  50 B, group information  50 C, and node information  50 D. 
     The shared information  50 A is data mutually shared with another node, and is, for example, disaster information, traffic information, and the like. 
     The connection node list  50 B is a list of communication addresses of a node permitted for connection. There are two types of communication addresses: one is a communication address of Wi-Fi Direct (e.g., a MAC address); and the other is a communication address of cellular communication (e.g., a phone number or an IP address).  FIG. 4  is a configuration example of the connection node list  50 B. The connection node list  50 B in this example includes a plurality of entries storing a set of an MAC address and a cellular communication address. 
     The group information  50 C is information relating to a group (P2P group) to which the node N belongs. If the node N has already joined in any group, information for identifying a group owner thereof and information for identifying a client node thereof are registered in the group information  50 C. Further, if the node N has not joined in any group, the fact of not joining in any group is registered. The node N manages whether the node N is a group owner or a client by the group information  50 C and executes processing in accordance with the group owner or processing in accordance with the client.  FIG. 5  is a configuration example of the group information  50 C. The group information  50 C in this example includes entries storing a set of a node identifier, a MAC address, and an owner bit for a number equal to a number of members of the group. The owner bit is set as value 1 when a node identified by a node identifier or a MAC address of a set thereof is a group owner, and otherwise, i.e., when the node is a client, the owner bit is set as value 0. 
     The node information  50 D is information in which position information or the like of other nodes is recorded.  FIG. 6  is a configuration example of the node information  50 D. The node information  50 D in this example includes a plurality of entries storing a set of a node identifier, a MAC address, position information, a moving direction, a velocity, an owner bit, and a group identifier. The node identifier is a name or a number for uniquely identifying a node. The MAC address is a communication address for the node. The position information is a latitude x, a longitude y, and a height z indicating a current position of the node. The moving direction and the velocity are a direction and a speed where the node is moving. The owner bit is a bit set as value 1 when a node identified by a node identifier or a MAC address of a set thereof is a group owner, and otherwise, i.e., when the node is a client, the owner bit is a bit set as value 0. With respect to the group identifier, when a node identified by a node identifier or a MAC address of a set thereof is being connected to a P2P group, a name or a number for uniquely identifying the group is recorded, and otherwise, a NULL is recorded, for example. 
     The processing unit  60  includes a microprocessor such as a MPU and a peripheral circuit thereof, and includes a function of reading the program  50 P from the storage unit  50  to execute the read program, and thereby making various types of processing units by the cooperation of the above hardware and program  50 P. Main processing units made by the processing unit  60  include a Wi-Fi connection control unit  60 A, a cellular communication control unit  60 B, and an automatic connection control unit  60 C. 
     The Wi-Fi connection control unit  60 A is a block that generates a packet of Wi-Fi Direct, transmits the generated packet through the wireless communication I/F unit  10 , and receives a packet of Wi-Fi Direct also through the wireless communication I/F unit  10 . The Wi-Fi connection control unit  60 A performs control in units such as “Device Discovery”, “Group Formation”, “WPS (Wi-Fi Protected Setup) Provisioning Phase 1”, and “WPS Provisioning Phase 2”. Further, the Wi-Fi connection control unit  60 A receives an event (command) from the automatic connection control unit  60 C to start control, and reports the result to the automatic connection control unit  60 C as an event (response). 
     The cellular communication control unit  60 B is a block that generates a packet of cellular communication, transmits the generated packet through the wireless communication I/F unit  20 , and receives a packet of cellular communication through the wireless communication I/F unit  20 . When receiving an event (command) from the automatic connection control unit  60 C, the cellular communication control unit  60 B performs control in accordance with the event and reports the result to the automatic connection control unit  60 C as an event (response). 
     The automatic connection control unit  60 C is a control unit located in an upper layer of the Wi-Fi connection control unit  60 A and the cellular communication control unit  60 B. The automatic connection control unit  60 C controls the cellular communication control unit  60 B, and thereby performs transmission/reception of a message across P2P groups of Wi-Fi Direct. Further, the automatic connection control unit  60 C controls the Wi-Fi connection control unit  60 A, and thereby performs automatic connection by Wi-Fi Direct. Specifically, when nodes come close to each other, for example, one group is automatically constructed and inter-node communication is carried out in the group. Further, when a new node comes close to an already-constructed group, the node automatically joins the already-constructed group. Still further, a node is automatically disconnected from the already-constructed group. The automatic connection control unit  60 C performs the information sharing method described with reference to  FIG. 2  in a Wi-Fi P2P network by such processing for connection and disconnection of Wi-Fi Direct. 
     Hereinafter, functions of the automatic connection control unit  60 C will be described in more detail. First, a function of connection and disconnection of Wi-Fi Direct will be described. Then, a control function relating to the information sharing described with reference to  FIG. 2  will be described. 
     &lt;Connection and Disconnection of Wi-Fi Direct&gt; 
     As illustrated in  FIG. 7 , when a group is formed between nodes (CASE 1), first, neighboring P2P nodes are searched by Device Discovery processing. When the P2P nodes are discovered, any one of the nodes becomes a group owner (GO) by GO Negotiation processing and the other node becomes a client to be connected. Next, WPS Provision Phase-1 (authentication phase) and Phase-2 (encryption phase) are sequentially executed. 
     In a case where connection is made to an existing GO (CASE 2), first, a neighboring P2P node is searched by Device Discovery processing. When the discovered P2P node is a GO, connection to the GO is made by Provisional Discovery processing. Next, WPS Provision Phase-1 (authentication phase) and Phase-2 (encryption phase) are sequentially executed. 
     In a case where connection is made to a Persistent GO (CASE 3), first, a neighboring P2P node is searched by Device Discovery processing. When the discovered P2P node is a Persistent GO, connection is made to the Persistent GO by Invitation processing. Next, WPS Provision Phase-2 (encryption phase) is sequentially executed. 
     As exemplarily illustrated in  FIG. 8 , a Device Discovery operation is executed. In other words, when receiving a search request from an automatic connection control unit, a Wi-Fi connection control unit in each node starts searching an adjacent node and alternately repeats a Search state and a Listen state. In the Search state, the Wi-Fi connection control unit transmits a Probe Request while sequentially switching a predetermined channel, and waits for a Probe response that is a response to the request. In the Listen state, the Wi-Fi connection control unit waits for a Probe Request from another node, and when receiving a Prove Request, returns a Probe Response for the received request. When the node N 1  is a client of a group, upon receipt of a Probe Response from the node N 2 , the Wi-Fi connection control unit of the node N 1  reports information of the adjacent node N 2  to a group owner of the group of node N 1  as adjacent node information. 
     As exemplarily illustrated in  FIG. 9 , a Device Discovery operation for an existing GO is executed. When a group with the node N 2  being a group owner is already constructed, the GO node N 2  returns a Probe Response for a Probe Request from the node N 1 . At that time, a P2P Device Info Attribute of the Probe Response from the GO node N 2  includes a list of clients belonging to the group (here, information of the nodes N 2  and N 3 ). 
     As exemplarily illustrated in  FIG. 10 , a GO Negotiation operation upon forming a group between terminals is executed. A GO Negotiation Request, a GO negotiation Response, and a GO Negotiation Confirmation are exchanged between nodes, and thereby one node becomes a GO to start broadcasting a beacon. 
     As exemplarily illustrated in  FIG. 11 , a Provision Discovery operation for connection to an existing GO is executed. For a Provision Discovery Request from the node N 1  to the node N 2 , the GO node N 2  returns a Provision Discovery Response to the node N 1 , and thereby the node N 1  is connected to the node N 2 . 
     As exemplarily illustrated in  FIG. 12 , an Invitation operation for connection to a Persistent-GO is executed. For an Invitation Request from the node N 1  to the node N 2 , the Persistent-GO node N 2  returns an Invitation Response to the node N 1 , and thereby the node N 1  is connected to the node N 2 . 
     As illustrated in  FIG. 13 , in a client-initiative disconnection, the client node N 1  transmits a Deauthentication or Disassociation Indication to the GO node N 2  to enable disconnection. Inversely, in a group-owner-initiative disconnection, the GO node N 2  transmits a Deauthentication or Disassociation Indication to the client node N 1 , to enable the client to be disconnected. 
     &lt;Control Function Relating to Information Sharing&gt; 
       FIG. 14  is a flowchart illustrating an operation of the node N according to the present example embodiment. Hereinafter, with reference to  FIG. 14 , an operation of the node N upon sharing information between the group G 1  and the group G 2  will be described. 
     In a state where groups G 1  and G 2  are formed as illustrated in  FIG. 1 , the automatic connection control units of the nodes N 11  to N 21  of the groups G 1  and G 2  transmit/receive a position-information notification message to/from another node at a constant cycle by cellular communication. Thereby, the automatic connection control units maintain contents of the node information  50 D illustrated in  FIG. 6  in the latest state (S 11 ). In the position information notification message transmitted from the node N, a current position of the node N detected in the GPS  70 , a moving direction, a velocity, a node identifier of the node N, a MAC address, an owner bit, and a group identifier are stored. The moving direction is obtained by detecting a direction of a current position of the node N this time viewed from a current position last time, for example. Further, the velocity is obtained by dividing a difference between the current position last time and the current position this time of the node N by a difference between detection clock times thereof, for example. A transmission destination includes all the nodes where cellular communication addresses are recorded on the connection node list  50 B. However, for another node connected to the same group as the node N managed by the group information  50 D, transmission may be performed by Wi-Fi Direct communication instead of cellular communication. Further, when receiving a position-information notification message from another node, the automatic connection control unit  60 D records the received message in the node information  50 D of the storage unit  50 . Specifically, when an entry including a node identifier or a MAC address matched with a node identifier or a MAC address in the received position information notification message does not exist in the node information  50 D, the automatic connection control unit  60 D stores the received position information notification message in a new entry and adds the new entry to the node information  50 D. When such entry exists, the automatic connection control unit  60 D overwrites the existing entry by the received position-information notification message. 
     The automatic connection control unit of the GO node N 11  of the group G 1  of a side of sending a delivery node discovers a group that is approaching the group G 1  based on the latest node information  50 D. Further, the automatic connection control unit predicts a shortest time that elapses before the discovered group moves to a predetermined range (S 12 ). In the same manner, the automatic connection control unit of the GO node N 16  of the group G 2  of a side of receiving a delivery node discovers a group that is approaching the group G 2  based on the latest node information  50 D. Further, the automatic connection control unit predicts a shortest time that elapses before the discovered group moves to a predetermined range (S 13 ). Hereinafter, details of a method in which the GO node N 11  discovers another group and predicts a shortest time that elapses before the other group moves to a predetermined range will be described. 
     The automatic connection control unit of the GO node N 11  sets, as a search region, a donut-shaped region W 2  illustrated in  FIG. 15  for each of the client nodes N 12  to N 15  of the group G 1 . Then, the automatic connection control unit detects a GO node of another group existing in the search region W 2 . The search region W 2  is a region excluding a range W 1  of a circle having a radius of a communicable maximum distance L 1  based on Wi-Fi Direct from a circle having a radius L 2  with a client node as a center. The automatic connection control unit uses, as the distance L 1 , a maximum value or an average value of distances between another node discovered by a Device Discovery procedure of the Wi-Fi Direct specification executed in the past and the GO node N 11 , for example. The distance L 2  is not limited when being longer than the distance L 1 , but when being excessively long, the automatic connection control unit needlessly detects another group that is less likely to move into the region W 1 . Therefore, it is preferable to set the distance L 2  an appropriate length. Note that the shape of the search region W 2  is not limited to a donut shape as illustrated in  FIG. 15 , and may be another shape such as a rectangle. 
     The automatic connection control unit of the GO node N 11  detects, from the node information  50 D illustrated in  FIG. 6 , a GO node in which the position information indicates a position within the search region W 2  of any one of the client nodes N 12  to N 15  (however, the GO node N 11  itself is excluded). In other words, the automatic connection control unit detects an entry in which XY coordinate values indicated by position information xi and yi are included in the search region W 2  and the owner bit is 1, from the node information  50 D. Hereinafter, the detected GO node will be written as another GO node. Next, the automatic connection control unit predicts a shortest time that elapses before another GO node moves to the region W 1  for each region W 1  of the client nodes N 12  to N 15  of the group G 1 . This is described below using the GO node N 21  and the client node N 12  as an example. 
     The automatic connection control unit of the GO node N 11  first calculates, from moving directions and velocities of the client node N 12  and another GO node N 21 , a relative velocity between the client node N 12  and the another GO node N 21 . Next, the automatic connection control unit researches whether an extended line extending in a vector direction of the relative velocity crosses the region W 1  of the client node by designating a current position of the another GO node N 21  as a start point. The automatic connection control unit determines that there is a possibility in which the another GO node N 21  moves to the region W 1  of the client node N 12  when the extended line crosses the region W 1 . The automatic connection control unit determines that there is no possibility of the above description when the extended line does not cross the region W 1 . When determining that there is a possibility, the automatic connection control unit divides a distance from an intersection between the extended line and an outer edge of the region W 1  of the client node N 12  to the current position of the another GO node N 21  by the relative velocity. The automatic connection control unit thereby calculates a shortest time that elapses before the another GO node N 21  moves to the region W 1 . For example, upon regarding W 1  of  FIG. 15  as the region W 1  of the client node N 12 , when a GO node N 31  drawn in  FIG. 15  is another GO node N 21 , an extended line extending from a current position thereof in a vector direction of a relative velocity does not cross the region W 1 . Therefore, it is determined that there is no possibility of moving to the region W 1 . On the other hand, when a GO node N 32  drawn in  FIG. 15  is another GO node N 21 , an extended line extending from a current position thereof in a vector direction of a relative velocity crosses the region W 1 . Therefore, it is determined that there is a possibility of moving to the region W 1 . Further, the automatic connection control unit divides a distance from an intersection P 32  between the extended line and an outer edge of the region W 1  to the GO node N 32  by the relative velocity, and calculates a time that elapses before the GO node N 32  moves to the region W 1 . The automatic connection control unit of the GO node N 11  executes the same calculation with respect to another GO node N 21  for the remaining client nodes N 13  to N 15 . Further, the automatic connection control unit sets a minimum time or an average time of times calculated for the client nodes N 12  to N 15  as a shortest time that elapses before the group G 2  to which another GO node N 21  belongs moves to a communicable range of a client node of the group G 1 . 
     Next, a method for discovering another group by the GO node N 16  of the group G 2  of a side of receiving a delivery node and predicting a shortest time that elapses before the other group moves to a predetermined range will be described in detail. 
     The automatic connection control unit of the GO node N 16  of the group G 2  sets, as a search region, a donut-shaped region W 2  illustrated in  FIG. 16  in the GO node N 16  itself and detects a client node of another group existing in the search region W 2 . The search region W 2  is a region excluding a range W 1  of a circle having a radius of a communicable maximum distance L 1  based on Wi-Fi Direct from a circle having a radius L 2  with the GO node N 16  as a center. The automatic connection control unit uses, as the distance L 1 , a maximum value or an average value of distances between another node discovered by a Device Discovery procedure of the Wi-Fi Direct specification executed in the past and the GO node N 16 , for example. The distance L 2  is not limited when being longer than the distance L 1 , but when being excessively long, the automatic connection control unit needlessly detects another node that is less likely to move to the region W 1 . Therefore, it is preferable to set an appropriate length. Note that the shape of the search region W 2  is not limited to a donut shape as illustrated in  FIG. 16 , and may be another shape such as a rectangle. 
     The automatic connection control unit of the GO node N 16  detects, from the node information  50 D illustrated in  FIG. 6 , a client node in which the position information indicates a position within the search region W 2  of the GO node N 16  (however, a client of the group G 2  is excluded). In other words, the automatic connection control unit detects an entry in which XY coordinate values indicated by position information xi and yi are included in the search region W 2  and an owner bit is 0, from the node information  50 D. Hereinafter, the detected client node will be written as another client node. Next, the automatic connection control unit predicts a shortest time that elapses before another client node moves to the region W 1  of the GO node N 16  of the group G 2 , as described below. This is described below using the GO node N 16  and the client node N 15  as an example. 
     The automatic connection control unit of the GO node N 16  first calculates a relative velocity between the GO node N 16  and the another client node N 15  from moving directions and velocities of the GO node N 16  and another client node N 15 . Next, the automatic connection control unit researches whether an extended line extending in a vector direction of the relative velocity crosses the region W 1  of the GO node N 16  by designating a current position of the another client node N 15  as a start point. Further, the automatic connection control unit determines that there is a possibility in which the another client node N 15  moves to the region W 1  of the GO node N 16  when the extended line crosses the region W 1 . The automatic connection control unit determines that there is no possibility of the above description when the extended line does not cross the region W 1 . When determining that there is a possibility, the automatic connection control unit divides a distance from an intersection between the extended line and an outer edge of the region W 1  of the GO node N 16  to the current position of the another client node N 15  by the relative velocity. The automatic connection control unit thereby calculates a shortest time that elapses before the another client node N 15  moves to the region W 1 . When a client node N 33  drawn in  FIG. 16  is regarded as a client node N 16 , for example, an extended line extending from a current position thereof in a vector direction of a relative velocity does not cross the region W 1 . Therefore, it is determined that there is no possibility of moving to the region W 1 . On the other hand, when a client node N 34  drawn in  FIG. 16  is regarded as a client node N 16 , an extended line extending from a current position thereof in a vector direction of a relative velocity crosses the region W 1 . Therefore, it is determined that there is a possibility of moving to the region W 1 . Further, the automatic connection control unit divides a distance from an intersection P 34  between the extended line and an outer edge of the region W 1  to the client node N 34  by the relative velocity. The automatic connection control unit thereby calculates a time that elapses before the client node N 34  moves to the region W 1 . The automatic connection control unit of the GO node N 11  executes the same calculation for the remaining client nodes N 12  to N 14  of the group G 1 . Further, the automatic connection control unit sets a minimum time or an average time of times calculated for all the client nodes of the group G 1  as a shortest time that elapses before the group G 1  moves to a communicable range of the group G 2 . 
     Referring again to  FIG. 14 , the automatic connection control unit of the GO node N 15  of the group G 1  discovers the group G 2  in step S 12  and calculates a shortest time necessary for a GO node of the group G 2  to move to a communicable range of a client of the group G 1 . The automatic connection control unit then executes delivery node selection (S 14 ), delivery node designation (S 15 ), and delivery node cutting (S 16 ) before the shortest time elapses. 
     In the delivery node selection (S 14 ), the automatic connection control unit of the GO node N 15  of the group G 1  selects, as a delivery node, a client node having a possibility of coming closest to or a possibility of approaching the GO node N 16  of the group G 2  at a predetermined distance threshold or less. Specifically, in  FIG. 15 , when the GO node N 32  is regarded as the GO node N 16 , among the client nodes N 12  to N 15 , a client node having a shortest length or a client node having a threshold or less of a perpendicular line (illustrated by a dashed line) drawn downward to an extended line of the GO node N 32  from the center of the region W 1  is selected as a delivery node. Alternatively, in the delivery node selection, a client node having a possibility of being connectable over a longest time or a client node having a possibility of being connectable over a time of a predetermined time threshold or more with respect to the GO node N 16  of the group G 2  may be selected as a delivery node. Specifically, in  FIG. 15 , when the GO node N 32  is regarded as the GO node N 16 , among the client nodes N 12  to N 15 , a client node in which a time obtained by dividing a length L where an extended line of the GO node  32  crosses the region W 1  by a relative velocity of the client node and the GO node N 32  is longest or a client node in which the time is equal to or larger than a threshold is selected as a delivery node. 
     Further, in the delivery node designation (S 15 ), the automatic connection control unit of the group G 1  designates information (e.g., a MAC address) of the node N 16  to be connected after disconnection from the group G 1 , a condition for reconnection to the group G 1 , and the like. As the condition for reconnection, reconnecting to the GO node N 11  after transmission/reception of shared data to/from the node N 16 , and reconnecting to the GO node N 11  when a certain time elapses after disconnection from the group G 1  are conceivable. 
     Further, in the delivery node cutting (S 16 ), the automatic connection control unit of the group G 1  executes a cutting procedure between the automatic connection control unit of the group G 1  and the automatic connection control unit of the client node N 15 . 
     On the other hand, the automatic connection control unit of the group G 2  discovers the group G 1  in step S 13  and calculates a shortest time necessary for a client of the group G 1  to move to a communicable range of a GO node of the group G 2 . The automatic connection control unit then executes temporal disconnection node selection (S 17 ), temporal disconnection node designation (S 18 ), and temporal disconnection node cutting (S 19 ) before the shortest time elapses. 
     In the temporal disconnection node selection (S 17 ), the automatic connection control unit of the group G 2  selects one or a plurality of client nodes connected to the group G 2  as temporal disconnection nodes. In the example of  FIG. 1 , the client node N 21  is selected as a temporal disconnection node. 
     Further, in the temporal disconnection node designation (S 18 ), the automatic connection control unit of the group G 2  designates information (e.g., a MAC address) of the node N 16  to be reconnected after disconnection from the group G 2  and a condition for reconnection to the group G 2 . As the condition for reconnection, reconnecting to the GO node N 16  when a certain time elapses after disconnection from the group G 2  is conceivable. In addition, reconnecting to the GO node N 16  at the time when the number of terminals of the group G 2  increases once, for example, to an upper limit of a connection client number and then decreases again after disconnection from group G 2  is also conceivable. 
     Further, in the temporal disconnection node cutting (S 19 ), the automatic connection control unit of the group G 2  executes a cutting procedure between the automatic connection control unit of the group G 2  and an automatic connection control unit of a node selected as a temporal disconnection node. 
     The automatic connection control unit of the delivery node N 15  disconnected from the group G 1  searches a neighboring group. This search is performed in conformity to a Device Discovery procedure of the Wi-Fi Direct specification. In  FIG. 14 , for example, the delivery node N 15  sends a probe request for Device Discovery processing, receives a probe response from an adjacent group G 2  (S 20 ), and thereby discovers the GO node N 16  of the group G 2 . When discovering the GO node N 16  of the group G 2 , the automatic connection control unit of the delivery node N 15  analyzes the adjacent group (S 21 ). In this analysis, it is determined whether the adjacent group is a connection destination requested by the delivery node designation. This determination is performed by researching whether a MAC address that is information for identifying the GO node N 16  included in a probe request or a probe response transmitted from the GO node N 16  of the group G 2  is matched with a MAC address of a connection destination designated by the delivery node designation, for example. When the MAC addresses are matched, it is determined that the group is connectable. When the MAC addresses are not matched, it is determined that the group is unconnectable and the automatic connection control unit continues to search another group. 
     When discovering the GO node N 16  of the group G 2  having the MAC address designated in the delivery node designation, the automatic connection control unit of the delivery node N 15  executes a connection procedure between the automatic connection control unit of the delivery node N 15  and the automatic connection control unit of the GO node N 16  (S 22 ). Thereby, the delivery node N 15  becomes a client node of the group G 2 . 
     The delivery node N 15  having become a client node of the group G 2  transfers shared information between the delivery node and the GO node N 16  (S 23 ). Specifically, the automatic connection control unit of the delivery node N 15  transmits the shared information  50 A (data D 1 ) on the storage unit to the GO node N 16  using the Wi-Fi connection control unit  60 A. Further, the automatic connection control unit of the GO node N 16  receives the shared information  50 A (data D 1 ) from the delivery node N 15  using the Wi-Fi connection control unit  60 A and stores the received information on the storage unit  50 . Inversely, the automatic connection control unit of the GO node N 16  transmits the shared information  50 A (data D 2 ) on the storage unit to the delivery node N 15  using the Wi-Fi connection control unit  60 A. Further, the automatic connection control unit of the delivery node N 15  receives the shared information  50 A (data D 2 ) from the GO node N 16  using the Wi-Fi connection control unit  60 A and stores the received information on the storage unit  50 . Thereafter, although not illustrated in  FIG. 14 , the data D 1  is transferred from the GO node N 16  to the client nodes N 17  to N 20  being connected. 
     Then, the delivery node N 15  is first disconnected from the group G 2  when a reconnection condition for the group G 1  is satisfied (S 24 ). At that time, a cutting procedure is executed under control of the automatic connection control unit of the GO node N 16  and the automatic connection control unit of the delivery node N 15 . The delivery node N 15  is then reconnected to the GO node N 11  of the group G 1  (S 25 ). At that time, a connection procedure is executed under control of the automatic connection control unit of the GO node N 11  and the automatic connection control unit of the delivery node N 15 . 
     The delivery node N 15  again having become a client of the group G 1  transfers shared information between the client node N 15  and the GO node N 16  (S 26 ). Specifically, the automatic connection control unit of the delivery node N 15  transmits the shared information  50 A (data D 2 ) on the storage unit to the GO node N 11  using the Wi-Fi connection control unit  60 A. Further, the automatic connection control unit of the GO node N 11  receives the shared information  50 A (data D 2 ) from the delivery node N 15  using the Wi-Fi connection control unit  60 A and stores the received information on the storage unit  50 . Thereafter, although not illustrated in  FIG. 14 , the data D 2  is transferred from the GO node N 11  to the client nodes N 11  to N 14  being connected. 
     On the other hand, the temporal disconnection node N 21  is reconnected to the GO node N 16  of the group G 2  when a reconnection condition for the group G 2  is satisfied (S 27 ). At that time, a connection procedure is executed under control of the automatic connection control unit of the GO node N 16  and the automatic connection control unit of the temporal disconnection node N 21 . The node N 21  again having become a client of the group G 2  transfers shared information between the client node N 21  and the GO node N 16  (S 28 ). Specifically, the automatic connection control unit of the GO node N 16  transmits the shared information  50 A (data D 1 ) on the storage unit to the node N 16  using the Wi-Fi connection control unit  60 A. Further, the automatic connection control unit of the node N 21  receives the shared information  50 A (data D 1 ) from the GO node N 16  using the Wi-Fi connection control unit  60 A, and stores the received information on the storage unit  50 . 
     In this manner, the present example embodiment transmits shared information between groups. 
     Second Example Embodiment 
     In the present example embodiment, group reconfiguration is performed by allowing a GO node belonging to one group to be a client node, and the node having become the client node is disconnected as a delivery node to be connected to the other group, whereby information is transferred via the delivery node. 
     Referring to  FIG. 17 , a communication system according to a second example embodiment of the present invention includes a plurality of nodes N 41  to N 47 . Each of the nodes N 41  to N 47  is a mobile wireless terminal mounted on a vehicle such as an automobile. Each of the nodes N 41  to N 47  is capable of performing wireless communication using a first communication method that can form a Peer-to Peer group and wireless communication using a second communication method different therefrom. The first communication method is Wi-Fi Direct, for example, and the second communication method is cellular communication such as 3G and LTE. Note that the first communication method is not limited to Wi-Fi Direct when being a communication method capable of forming a Peer-to-Peer group with another wireless terminal. Further, the second communication method is not limited to cellular communication when being a wireless communication method capable of performing longer-distance communication than the first communication method. 
     In  FIG. 17 , a plurality of nodes N 41  to N 47  configure two Peer-to-Peer groups G 1  and G 2  (hereinafter, simply referred to as groups) by the first communication method. The group G 1  is formed with the node N 41  as a parent (group owner), and the nodes N 42  to N 43  are children (clients) thereof. Further, the group G 2  is formed with the node N 44  as a group owner, and the nodes N 45  to N 47  are clients thereof. Further, data D 1  and data D 2  are shared in the group G 1  and the group G 2 , respectively. Further, the nodes N 41  to the node N 43  of the group G 1  are moving together in a direction indicated by an arrow A 1 , and the nodes N 44  to the node  47  of the group G 2  are moving together in a direction indicated by an arrow A 2  opposite to the arrow A 1 . Such a situation appears when three vehicles mounted with the nodes N 41  to N 43  of the group G 1  are running in a column on a road, and four vehicles mounted with the nodes N 44  to N 47  of the group G 2  are running in a column on a traffic lane opposite to the road, for example. 
     Here, a maximum number of client nodes connectable to one group owner (hereinafter, referred to as a GO) is assumed to be five for description convenience. Under such limitation, the GO node N 41  of the group G 1  and the GO node N 44  of the group G 2  of  FIG. 17  are connectable to a new node. Therefore, when the group G 1  is a group of a side of sending a delivery node and the group G 2  is a group of a side of receiving a delivery node, for example, in a situation where any one of the client nodes N 42  to N 43  of the group G 1  passes near the GO node N 44  of the group G 2 , it is possible to connect the delivery node to the GO node N 44  upon disconnection of the client nodes N 42  to N 43  as a delivery node. However, when the client nodes N 42  to N  43  do not pass near the GO node N 44 , it is not possible to connect to the GO node N 44  even when the client nodes N 42  to N 43  are disconnected as delivery nodes. In the present example embodiment, even in such a case, it is possible to share information using a delivery node when the GO node N 41  of the group G 1  passes near the GO node N 44  of the group G 2 . 
       FIG. 18  is a flowchart illustrating an operation of the communication system according to the present example embodiment. Hereinafter, with reference to  FIG. 18 , an operation for transferring shared information between the group G 1  and the group G 2  in the communication system according to the present example embodiment will be described. In the present example embodiment, there is described an example in which the group G 1  operates as a group of a side of sending a delivery node, and the group G 2  operates as a group of a side of receiving a delivery node. However, it is also possible to send a delivery node from both groups. As a method for determining a group of a side of sending a delivery node, it is possible to use a method for determining based on a magnitude of a group number or a method for determining based on a negotiation between groups, for example. 
     In a state where groups G 1  and G 2  are formed, the GO node N 41  of the group G 1  of a side of sending a delivery node discovers the group G 2  present outside a communicable range of the group G 1  defined by the first communication method. When predicting that there is a possibility in which a GO node of the group G 2  moves into a communicable range of a GO node of the group G 1  and a node, among nodes of the group G 1 , that comes closest to or a node that can be connected for a longest time to the GO node of the group G 2  is the GO node, the GO node  41  predicts a shortest time that elapses before the GO node of the group G 2  moves into the communicable range of the GO node of group G 1  (step S 31 ). 
     Next, the GO node N 41  of the group G 1  performs group reconfiguration before the predicted time elapses, in preparation for transferring information through a delivery node between the group G 1  and the group G 2 . In other words, the GO node N 41  of the group G 1  reconfigures the group G 1  to change the GO node before the predicted time elapses (step S 32 ). Specifically, for example, the GO node  41  instructs the client node N 42  to regard the node N 43  as a reconnection destination to disconnect the client node N 42  from the group G 1 , and instructs the client node N 43  to regard the node N 42  as a reconnection destination to disconnect the client node N 43  from the group G 1 . Accordingly, the GO node N 41  is made to be a sole owner that is not a group owner. Thereby, the group G 1  is temporarily disorganized. Thereafter, the nodes N 42  to N 43  are connected to each other in accordance with the instructions, and any one of the nodes becomes a GO node and the other becomes a client node to configure a group G 1 . The node N 41  is connected to the GO node of the formed group G 1  and becomes a client node of the group G 1 . As illustrated in  FIG. 17 , it is assumed that the node N 43  has become a new GO node. 
     The node N 43  having become the new GO node selects, as a delivery node, the client node N 41  that is originally a GO node, and instructs the delivery node to be connected to the group G 2  and to be disconnected from the group G 1  (step S 33 ). As a method for selecting the node N 41  as a delivery node, there is a method in which the client node N 41  requests the GO node N 43  to cause the node N 41  to be a delivery node, when the client node N 41  is connected to the GO node N 43 . Alternatively, there is a method in which after group reconfiguration, the GO node N 43  detects and determines that a client node that comes closest to or a client node that can be connected over a longest time to the GO node N 44  becomes the node N 41 . Note that the disconnection of the delivery node N 41  may be completed before the groups G 1  and G 2  approach each other at a maximum communicable distance or less defined by the first communication method or may be completed after the approach. 
     When discovering the GO node N 44  of the group  2  by a Device Discovery procedure of the Wi-Fi Direct specification, for example, the delivery node N 41  disconnected from the group G 1  is connected to the GO node N 44  and transfers shared information between the delivery node N 41  and the GO node N 44  (step S 34 ). Specifically, the delivery node N 41  transmits the data D 1  to the GO node N 44 , and the GO node N 44  transmits the data D 2  to the delivery node N 41 . Thereby, the GO node N 44  of the group G 2  can acquire the data D 1  shared in the group G 1 . Moreover, the data D 1  is further transferred from the GO node N 44  to the client nodes N 45  to N 47 , and thereby the client nodes N 45  to N 47  can acquire the data D 1  shared in the group G 1 . 
     Thereafter, the delivery node N 41  is disconnected from the group G 2  and is reconnected to the GO node N 43  of the group G 1 , and thereby transfers information between the node N 41  and the GO node N 43  (step S 35 ). Specifically, the delivery node N 41  transmits the data D 2  to the GO node N 43 . Thereby, the GO node N 43  of the group G 1  can acquire the data D 2  shared in the group G 2 . Further, the data D 2  is further transferred from the GO node N 43  to the client node N 42 , and thereby the client node N 42  can acquire the data D 2  shared in the group G 2 . 
     In this manner, shared information can be transmitted between the group G 1  and the group G 2  via the delivery node N 41 . 
       FIG. 19  visually illustrates an influence on information sharing by a delivery node caused by reconfiguration of the group G 1 . In a case of  FIG. 19(A)  in which the group G 1  is not reconfigured, all the client nodes N 42  to N 43  of the group G 1  of a side of sending a delivery node distantly pass the GO node N 44  of the group G 2 . Therefore, it is not possible for the client nodes N 42  to N 43  to be connected to the GO node N 44  of the group G 2  even by being disconnected as a delivery node. On the other hand, in a case of  FIG. 19(B)  in which the group G 1  is reconfigured, the client node N 41  (the GO node before reconfiguration) of the group G 1  after reconfiguration of a side of sending a delivery node approaches and passes the GO node N 44  of the group G 2 . Therefore, the client node N 41  can be connected to the GO node N 44  of the group G 2  by being disconnected as a delivery node. 
     Hereinafter, the configuration and operation of the communication system according to the present example embodiment will be descried in more detail. 
     The node N used as the nodes N 41  to N 47  is basically the same as the node N described with reference to  FIG. 3  except that functions of the automatic connection control unit  60 C differ. Further, among the functions of the automatic connection control unit  60 C of the node N used as the nodes N 41  to N 47 , functions of connection and disconnection of Wi-Fi Direct are the same as in the node N described with reference to  FIG. 3 . Among the functions of the automatic connection control unit  60 C of the node N used as the nodes N 41  to N 47 , a control function relating to information sharing described with reference to  FIG. 18  will be described. 
     &lt;Control Function Relating to Information Sharing&gt; 
       FIG. 20  is a flowchart illustrating an operation of the node N according to the present example embodiment. With reference to  FIG. 20 , an operation of the node N upon sharing information between the group G 1  and the group G 2  will be described. 
     In a state where groups G 1  and G 2  as illustrated in  FIG. 17  are formed, the automatic connection control units of the nodes N 41  to N 47  of the groups G 1  and G 2  transmit/receive a position-information notification message to/from another node at a constant cycle by cellular communication. Thereby, the automatic connection control units maintain contents of the node information  50 D illustrated in  FIG. 6  in the latest state (S 41 ). The operation of step S 41  is the same as the operation of step S 11  of  FIG. 14 . 
     The automatic connection control unit of the GO node N 41  of the group G 1  of a side of sending a delivery node discovers the group G 2  that is approaching the group G 1  based on the latest node information  50 D. When predicting that there is a possibility in which a GO node of the group G 2  moves into a communicable range of a GO node of the group G 1  and a node, among the nodes of the group G 1 , that comes closest to or a node that can be connected for a longest time to the GO node of the group G 2  is a GO node, the automatic connection control unit predicts a shortest time that elapses before the GO node of the group G 2  moves into the communicable range of the GO node of the group G 1  (S 42 ). The operation of step S 42  is executed by replacing the client nodes N 12  to N 15  of the center of  FIG. 15  with the respective nodes of the group G 1  and by executing the processing described with reference to  FIG. 15 . 
     Next, when predicting the shortest time that elapses before the GO node of the group G 2  moves into the communicable range of the GO node of the group G 1 , the automatic connection control unit of the GO node N 41  reconfigures the group G 1  before the shortest time elapses (S 44 ). By the reconfiguration of the group G 1 , the GO node N 41  becomes a client node of the group G 1  and the client node N 43  becomes a GO node in  FIG. 20 . 
     Next, the client node N 41  requests the GO node N 43  to disconnect the node N 41  as a delivery node (S 45 ). The GO node N 43  disconnects the client node N 41  as a delivery node in accordance with this request (S 46 ). 
     The automatic connection control unit of the delivery node N 41  disconnected from the group G 1  searches a neighboring group. This search is performed in conformity to a Device Discovery procedure of the Wi-Fi Direct specification. For example, in  FIG. 20 , the client node N 41  transmits a probe request for Device Discovery processing, receives a probe response from an adjacent group G 2  (S 47 ), and thereby discovers the GO node N 44  of the group G 2 . When discovering the GO node N 44  of the group G 2 , the automatic connection control unit of the client node N 41  analyzes the adjacent group (S 48 ). In this analysis, it is determined whether the adjacent group is the GO node of the group G 2  discovered in step S 42 . This determination is performed by researching whether a MAC address that is information for identifying the GO node N 44  included in a probe request or a probe response transmitted from the GO node N 44  of the group  2  is matched with a MAC address of the GO node of the group G 2  discovered in step S 42 , for example. When the MAC addresses are matched, it is determined that the group is connectable. When the MAC addresses are not matched, it is determined that the group is unconnectable and the automatic connection control unit continues to search another group. 
     When discovering the GO node N 44  of the group G 2 , the automatic connection control unit of the delivery node N 41  executes a connection procedure between the automatic connection control unit of the delivery node N 41  and the automatic connection control unit of the GO node N 44  (S 49 ). Thereby, the delivery node N 41  becomes a client node. 
     The delivery node N 41  having become a client of the group G 2  transfers shared information between the delivery node N 41  and the GO node N 44  (S 50 ). Specifically, the automatic connection control unit of the delivery node N 41  transmits the shared information  50 A (data D 1 ) on the storage unit to the GO node N 44  using the Wi-Fi connection control unit  60 A. The automatic connection control unit of the GO node N 44  receives the shared information  50 A (data D 1 ) from the delivery node N 41  using the Wi-Fi connection control unit  60 A and stores the received information on the storage unit  50 . Inversely, the automatic connection control unit of the GO node N 44  transmits the shared information  50 A (data D 2 ) on the storage unit to the delivery node N 41  using the Wi-Fi connection control unit  60 A. The automatic connection control unit of the delivery node N 41  receives the shared information  50 A (data D 2 ) from the GO node N 44  using the Wi-Fi connection control unit  60 A and stores the received information on the storage unit  50 . Thereafter, although not illustrated in  FIG. 20 , the data D 1  is transferred from the GO node N 44  to the client nodes N 45  to N 47  being connected. 
     Subsequently, the delivery node N 41  is first disconnected from the group G 2  when a condition for reconnection to the group G 1  is satisfied (S 51 ). The delivery node N 41  is then reconnected to the GO node N 43  of the group G 1  (S 52 ). The delivery node N 41  again having become a client of the group G 1  transfers shared information between the client node N 41  and the GO node N 43  (S 53 ). Thereafter, although not illustrated in  FIG. 20 , the data D 2  is transferred from the GO node N 43  to the client node N 42  being connected. 
     In this manner, the present example embodiment transmits shared information between groups. 
     Third Example Embodiment 
     In the present example embodiment, one group is disorganized, and each of the nodes having become a sole node is connected to the other group as a delivery node, whereby information is transferred through the delivery node. 
     Referring to  FIG. 21 , a communication system according to a third example embodiment of the present invention is configured by a plurality of nodes N 51  to N 56 . Each of the nodes N 51  to N 56  is a mobile wireless terminal mounted on a vehicle such as an automobile. Each of the nodes N 51  to N 56  is capable of performing wireless communication using a first communication method that can form a Peer-to-Peer group and wireless communication using a second communication method different therefrom. The first communication method is Wi-Fi Direct, for example, and the second communication method is cellular communication such as 3G and LTE. Note that the first communication method is not limited to Wi-Fi Direct when being a communication method capable of forming a Peer-to-Peer group with another wireless terminal. Further, the second communication method is not limited to cellular communication when being a wireless communication method capable of performing longer-distance communication than the first communication method. 
     In  FIG. 21 , a plurality of nodes N 51  to N 56  configure two Peer-to-Peer groups G 1  and G 2  (hereinafter, simply referred to as groups) by the first communication method. The group G 1  is formed with the node N 51  as a parent (group owner), and the nodes N 52  to N 53  are children (clients) thereof. Further, the group G 2  is formed with the node N 54  as a group owner, and the nodes N 55  to N 56  are clients thereof. Still further, data D 1  and data D 2  are shared in the group G 1  and the group G 2 , respectively. Moreover, the nodes N 51  to N 53  of the group G 1  are moving together in a direction indicated by an arrow A 1 , and the node N 54  to N 56  of the group G 2  are moving together in a direction indicated by an arrow A 2  opposite to the arrow A 1 . Such a situation appears when three vehicles mounted with the nodes N 51  to N 53  of the group G 1  are running in a column on a road, and three vehicles mounted with the nodes N 54  to N 56  of the group G 2  are running in a column on a traffic lane opposite to the road, for example. 
     Here, a maximum number of client nodes connectable to one group owner (hereinafter, referred to as a GO) is assumed to be five for description convenience. Under such limitation, the GO node N 51  of the group G 1  and the GO node N 54  of the group G 2  of  FIG. 21  can be further connected to three new nodes, respectively. This means that the groups G 1  and G 2  can be integrated into one group. Therefore, in the present example embodiment, all nodes belonging to any one of the groups G 1  and G 2  are set as a delivery node, and thereby data sharing between the groups G 1  and G 2  is achieved. As a method for determining a group of a side of sending a delivery node, it is possible to use a method for determining based on a magnitude of a group number or a method for determining based on a negotiation between groups, for example. The following will describe an example in which the group G 1  operates as a group of a side of sending a delivery node and the group G 2  operates as a group of a side of receiving a delivery node. 
       FIG. 22  is a flowchart illustrating an operation of the communication system according to the present example embodiment. With reference to  FIG. 22 , operations for transferring shared information between the group G 1  and the group G 2  in the communication system according to the present example embodiment will be described. 
     In a state where groups G 1  and G 2  are formed as illustrated in  FIG. 21 , the GO node N 51  of the group G 1  of a side of sending a delivery node discovers the group G 2  present outside a communicable range of the group G 1  defined by the first communication method. When there is a possibility in which the total numbers of members of the groups G 1  and G 2  is equal to or smaller than an upper-limit number per group and the GO node N  54  of the group G 2  moves to the communicable range defined by the first communication method of all the nodes N 51  to N 53  of the group G 1 , the GO node N 51  predicts a shortest time necessary for the GO node N 54  to move into the communicable range of the nodes N 51  to N 53  of the group G 1  (step S 61 ). 
     Next, the GO node N 15  of the group G 1  performs group reconfiguration before the predicted time elapses, in preparation for transferring information through a delivery node between the group G 1  and the group G 2 . In other words, before the predicted time elapses, the GO node N 51  of the group G 1  instructs each of the nodes N 51  to N 53  to be connected to the group G 2  as a delivery node and disorganizes the group G 1  (S 62 ). Specifically, the GO node N 51  disconnects the client nodes N 52  and N 53  from the group G 1  and then makes the node N 51  to be a sole node that is not a group owner, for example. 
     Next, when discovering the GO node N 54  of the group G 2 , for example, the nodes N 51  to N  53  are connected to the GO node N 54  by a Device Discovery procedure of the Wi-Fi Direct specification, and transfer shared information between the nodes N 51  to N  53  and the GO node N 54  (step S 63 ). Specifically, any one of the nodes N 51  to N 53  transmits the data D 1  to the GO node N 54 , and the GO node N 54  transmits the data D 2  to the nodes N 51  to N 53 . Thereby, the GO node N 54  of the group G 2  can acquire the data D 1  shared in the group G 1 , and the nodes N 51  to N 53  can acquire the data D 2  shared in the group G 2 . Moreover, the data D 1  is further transferred from the GO node N 54  to the client nodes N 55  to N 56 , and thereby the client nodes N 55  to N 56  can acquire the data D 1  shared in the group G 1 . 
     Operations of the nodes N 51  to N 53  thereafter are optional. When moving thereafter in the same direction as the GO node N 54 , the nodes N 51  to N 53  may remain in the group G 2 , for example. Alternatively, when moving in a direction different from the GO node N 54 , the nodes N 51  to N 53  may be disconnected from the group G 2  and then connected to each other to form the same group G 1  again. 
     In this manner, all the nodes N 51  to N 53  of the group G 1  become a delivery node, and thereby shared information can be transmitted between the group G 1  and the group G 2 . 
     Hereinafter, the configuration and operation of the communication system according to the present example embodiment will be described in more detail. 
     The node N used as the node N 51  to N 56  is basically the same as the node N described with reference to  FIG. 3  except that functions of the automatic connection control unit  60 C differ. Further, among the functions of the automatic connection control unit  60 C of the node N used as the nodes N 51  to N 56 , functions of connection and disconnection of Wi-Fi Direct are the same as in the node N described with reference to  FIG. 3 . Among the functions of the automatic connection control unit  60 C of the node N used as the nodes N 51  to N 56 , the following will describe a control function relating to information sharing described with reference to  FIG. 22 . 
     &lt;Control Function Relating to Information Sharing&gt; 
       FIG. 23  is a flowchart illustrating an operation of the node N according to the present example embodiment. With reference to  FIG. 23 , the following will describe an operation of the node N upon sharing information between the group G 1  and the group G 2 . 
     In a state where groups G 1  and G 2  as illustrated in  FIG. 21  are formed, the automatic connection control units of the nodes N 51  to N 56  of the groups G 1  and G 2  transmit/receive a position-information notification message to/from another node at a constant cycle by cellular communication. Thereby, the automatic connection control units maintain contents of the node information  50 D illustrated in  FIG. 6  in the latest state (S 71 ). The operation of step S 71  is the same as the operation of step S 11  of  FIG. 14 . 
     The automatic connection control unit of the GO node N 51  of the group G 1  of a side of sending a delivery node discovers a group that is approaching the group G 1  based on the latest node information  50 D. Further, the automatic connection control unit predicts a shortest time that elapses before the discovered group moves to a predetermined range (S 72 ). The operation of step S 72  is the same as the operation of step S 12  of  FIG. 14 . 
     Subsequently, the automatic connection control unit of the GO node N 41  discovers the group G 2  that is approaching the group G 1  by the operation of step S 72 . When determining that the GO node N 54  of the group G 2  moves to a region W 1  of the client nodes N 52  to N 53  of the group G 1 , the automatic connection control unit predicts whether a total of the numbers of the members of the groups G 1  and G 2  is equal to or smaller than an upper limit of the number of the members of one group and a shortest time that elapses before the GO node N 54  of the group G 2  moves to a region W 1  of the GO node N 51  of the group G 1  (step S 73 ). The prediction processing of the shortest time can be carried out using the GO node N 51  instead of the client nodes N 12  to N 16  in the operation of step S 12  of  FIG. 14 . Further, the total number of members of the groups G 1  and G 2  can be obtained by adding a number of nodes of the group G 1  managed by the group information  50 C and a number of nodes belonging to the discovered group G 2 , for example. 
     Moreover, the automatic connection control unit of the GO node N 51  of the group G 1  calculates that there is a possibility in which the GO node N 54  of the group G 2  moves to the region W 1  of the GO node N 51  of the group G 1 , and calculates a shortest time that elapses before the GO node N 54  moves to the region W 1 . The automatic connection control unit performs disorganization of the group G 1  before a shorter time of the above-calculated shortest time and the shortest time calculated in step S 72  elapses (S 74 ). By this disorganization of the group G 1 , the GO node N 51  and the client nodes N 52  to N 53  become sole nodes, respectively. Before the disorganization, the GO node N 51  designates, for the client nodes N 51  to N 53 , information of a connection destination as a delivery node such as a group identifier of the group G 2  or a MAC address of the GO node N 54 . 
     The automatic connection control units of the nodes N 51  to N 53  having become sole nodes search a neighboring group. This search is performed in conformity to a Device Discovery procedure of the Wi-Fi Direct specification. In  FIG. 23 , N 51  to N 53  transmit a probe request for Device Discovery processing, receive a probe response from an adjacent group G 2  (S 75 ), and thereby discover the GO node N 54  of the group G 2 . When discovering the GO node N 54  of the group G 2 , the automatic connection control units of the nodes N 51  to N 53  analyze the adjacent group (S 76 ). In this analysis, it is determined whether the adjacent group is a GO node of the group G 2  to be connected as a delivery node. This determination is performed by researching whether a MAC address that is information for identifying the GO node N 54  included in a probe request or a probe response transmitted from the GO node N 54  of the group G 2  is matched with a MAC address of the GO node of the group G 2  designated for connection as a delivery node before the group disorganization, for example. When the MAC addresses are matched, it is determined that the group is connectable. When the MAC addresses are not matched, it is determined that the group is unconnectable and the automatic connection control unit continues to search another group. 
     When discovering the GO node N 54  of the group G 2 , the automatic connection control unit of each of the nodes N 51  to N 53  executes a connection procedure between the own unit and the automatic connection control unit of the GO node N 54  (S 77 ). Thereby, the nodes N 51  to N 53  become client nodes of the group G 2 , respectively. 
     The nodes N 51  to N 53  having become the client nodes of the group G 2  transfer shared information between the nodes N 51  to N 53  and the GO node N 54  (S 78 ). Specifically, the automatic connection control unit of the node N 51  transmits the shared information  50 A (data D 1 ) on the storage unit to the GO node N 54  using the Wi-Fi connection control unit  60 A, for example. The automatic connection control unit of the GO node N 54  receives the shared information  50 A (data D 1 ) from the node N 51  using the Wi-Fi connection control unit  60 A, and stores the received information on the storage unit  50 . Further, the automatic connection control unit of the GO node N 54  transmits the shared information  50 A (data D 2 ) on the storage unit to the nodes N 51  to N 53  using the Wi-Fi connection control unit  60 A. The automatic connection control units of the nodes N 51  to N 53  receive the shared information  50 A (data D 2 ) from the GO node N 54  using the Wi-Fi connection control unit  60 A, and stores the received information on the storage unit  50 . Further, the data D 1  is transferred from the GO node N 54  to the client nodes N 55  to N 56  being connected. 
     In this manner, the present example embodiment transmits shared information between groups. 
     As a modified example of the present example embodiment, a configuration in which the GO node N 54  of the group G 2  executes the same steps S 72  and S 73  as in the GO node N 51  of the group G 1  is conceivable. In this case, before disorganization of each group, the GO node N 51  of the group G 1  and the GO node N 54  of the group G 2  may negotiate group disorganization using communication by the second communication method with a GO node of a partner group to determine whether to disorganize any one of the groups. Alternatively, before disorganization of each group, the GO node N 51  of the group G 1  and the GO node N 54  of the group G 2  may determine which one of the groups to disorganize based on a magnitude of a group number, for example. 
     Other Example Embodiments 
     The present invention is not limited to the above-described example embodiments and can be subjected to various other types of additions/modifications. For example, example embodiments as described below are included in the present invention. 
     In the above-described example embodiments, the automatic connection control unit  60 C of the node N directly transmitted/received a position-information notification message to/from another node. However, a position-information notification message may be transmitted/received among nodes via a server SB as illustrated in  FIG. 24 , for example. At that time, the automatic connection control unit  60 C of each node N transmits a position-information notification message to the server SB at a constant cycle by cellular communication using the cellular communication control unit  60 B. The server SB stores node information (hereinafter, referred to as server-side node information) similar to the node information  50 D. When an entry including a node identifier or a MAC address matched with a node identifier or a MAC address in the received position-information notification does not exist in the server-side node information, the server SB stores the received position-information notification message in a new entry, and adds the stored message to the server-side node information. When such entry exists, the server SB overwrites the existing entry by the received position-information notification message. Further, the automatic connection control unit  60 C of each node N downloads server-side node information from the server SB at a constant cycle by cellular communication using the cellular communication control unit  60 B, and stores the downloaded information on the storage unit  50  as the node information  50 D. 
     Further, in the above-described example embodiments, the automatic connection control unit  60 C of the node N predicts the presence or absence of a possibility in which a discovered group moves to a predetermined range of the group of node N and a shortest time that elapses before the movement thereto based on a position and a velocity (a moving direction and a speed) of a node. However, other pieces of information may be exchanged between nodes by a position-information notification message to be used for the prediction. For example, the automatic connection control unit  60 C of the node N may use information detected or managed by a car navigation system installed in a vehicle mounted with the node N. Thereby, the automatic connection control unit  60 C may predict the presence or absence of a possibility in which a discovered group moves to a predetermined range of the group of node N and a shortest time that elapses before the movement thereto. As an example of the usable information, there is route information estimated from a curvature of a curve of a currently-running road or a destination. 
       FIG. 25  illustrates an example in which prediction is performed using a curvature of a currently-running road. A node N  61  belonging to the group G 1  is running in an arrow direction along a curve of a road of a curvature a, and a node N 62  belonging to the group G 2  is running in an arrow direction on an opposite traffic lane of the same curve. In such a case, it is difficult to predict whether the nodes approach each other, by only using current positions and moving velocities of the nodes N 61  and N 62 . However, when currently-running curvatures are considered, moving routes of the node N 61  and the node N 62  can be predicted as illustrated with dashed lines in  FIG. 25 . Therefore, it is possible to predict a possibility accurately in which one node N 61  moves to a predetermined range of the other node N 62  and a shortest time necessary for the movement thereto. 
       FIG. 26  illustrates an example in which prediction is performed using a route estimated from a destination. In  FIG. 26 , a dashed line extending from a node N 61  to a destination thereof is a moving route derived by a car navigation system from a current position of the node N 61  and a destination thereof. In the same manner, a dashed line extending from a node N 62  to a destination thereof is a moving route derived by a car navigation system from a current position of the node N 62  and a destination thereof. The moving routes of the nodes N 61  and N 62  are partially overlapped. Accordingly, it is possible to accurately predict a possibility in which one node N 61  moves to a predetermined range of the other node N 62  and a shortest time necessary for the movement thereto, based on a current position, a velocity, and a moving route of the node N 61  and a current position, a velocity, and a moving route of the node N 62 . 
     It should be noted that the present invention is based upon and claims the benefit of priority from Japanese patent application No. 2014-264496, filed on Dec. 26, 2014, and the contents described in the patent application are incorporated herein in its entirety. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to a P2P network including a plurality of nodes (wireless terminals) that can dynamically form a group. 
     REFERENCE SIGNS LIST 
     
         
         
           
             G 1  to G 2  . . . Group 
             GO . . . Group owner 
             N . . . Node 
             D . . . Data 
               10 ,  20  . . . Wireless communication I/F unit 
               30  . . . Operation input unit 
               40  . . . Screen display unit 
               50  . . . Storage unit 
               50 A . . . Shared information 
               50 B . . . Connection node list 
               50 C . . . Group information 
               50 D . . . Node information 
               50 P . . . Program 
               60  . . . Processing unit 
               60 A Wi-Fi connection control unit 
               60 B . . . Cellular communication control unit 
               60 C . . . Automatic connection control unit 
               70  . . . GPS