JPH05122119A - Routing system - Google Patents

Abstract

PURPOSE:To suppress the drop of efficiency due to route searching in a network for radio communication. CONSTITUTION:A mobile station 11 transmits a route searching packet to which its position is also added. A mobile station 12 receiving the packet supposes a segment connecting the station 1 transmitting the packet to a fixed station 13 and finds out a distance between the segment and its own station. Only when the distance is less than a previously determined value, the station 12 repeats the packet, adds '1' to the number of repeating stations for the packet, adds its identification(ID) code as the ID code of a repeating station and then transmits the added data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a routing system, and more particularly to a routing system between a mobile station and a fixed station in a network for wirelessly transmitting packet data.

[0002]

2. Description of the Related Art A conventional routing system is a network for carrying out packet exchange by wireless communication for mobile stations such as automobiles, assuming relay by other mobile stations.
In order to perform packet exchange between a mobile station and a fixed station, each mobile station and the fixed station grasp the route information between the mobile station and the fixed station, and furthermore, the position of each mobile station changes drastically. In addition, it is necessary to periodically update the route information.

As an example, each mobile station must periodically send a route search packet with a unique identification code, and other mobile stations that have received the packet must have the packet relayed by themselves. For example, the identification code of its own station is added to the packet as a relay station and retransmitted, and the packet reaches the intended fixed station via some stations.

Packets that have passed through various routes from the originating mobile station arrive at the fixed station. The shortest packet is selected from the packets and adopted, and the relay station is traced in reverse by the route. And notifies the originating mobile station.

[0005]

According to the conventional routing method described above, a route search packet is periodically transmitted from each mobile station, and the mobile station that receives the route search packet determines whether or not the packet has been relayed once by itself. If the relaying is performed only by doing so, there is a drawback that a very large number of packets will spread to every corner of the network, and the transmission efficiency of the network will suddenly decrease each time.

[0006]

According to the routing method of the present invention, each mobile station grasps its own position by a position information transmitting station which is appropriately arranged and periodically transmits position information, and a route search packet is used. When transmitting the, the identification code of the fixed station currently closest to the own station is obtained from the identification code of the fixed station and the position correspondence table that each has, and the identification code and the identification code of the own station In addition, the position of your own station is also added for transmission.

Then, the mobile station receiving the packet is
The position of the fixed station is obtained from the identification code of the fixed station of the same packet and the correspondence table of its position to the identification code of the fixed station that each has, and further, the position of this fixed station and the position of the transmitting station of the same packet Assuming a line segment connecting the position of the transmitting station and the target fixed station, calculate the distance between itself and that line segment, and relay the same packet depending on the distance from the line segment. If the distance is equal to or smaller than the determined value, the packet is relayed by adding information to the effect that the node relays.

This limits the mobile stations that relay the route search packet and reduces the number of route search packets that travel around the network.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is an explanatory view of the relay status of a route search packet in an embodiment of the present invention. Also, in FIG.
It is a figure which shows an example of the position information transmission station in a present Example. As shown in Figure 2, divide the area into square areas,
Number each area. Hereinafter, this number will be referred to as a region number.

Further, in each area, there are sparsely located mobile stations 22 in which the position information transmitting stations 21 are arranged at fixed positions at appropriate intervals and packet exchange with the fixed stations is performed. It should be noted that all the position information transmitting stations including the position information transmitting station 21 regularly and alternately transmit the area code in which they exist, with the same transmission output and the same frequency.

FIG. 3 is a diagram showing an example of a mobile station management table in the present embodiment. Therefore, the mobile station 22 receives the area number transmitted by the nearby position information transmitting station and stores the area number of the station having the strongest signal strength as the position of the own station in the management table of the mobile station shown in FIG. . Regarding the position of this own station, the oldest one is discarded, and the station having a stronger signal strength is sequentially updated to always store the latest one. In addition, in the mobile station management table of FIG. 3, in addition, the area number of each fixed station is managed as the position of the fixed station.

Next, centering on FIG. 1, a route search packet is transmitted from the mobile station 11 and, after passing through the mobile station 12,
A procedure for reaching the fixed station 13 and further obtaining the route information from the mobile station 11 will be specifically described.

FIG. 4 is a diagram showing an example of transmission items of the route search packet of this embodiment.

First, the mobile station 11 refers to the position of its own station and the position of each fixed station in the management table of the mobile station shown in FIG. 3, checks the closest fixed station, and identifies the fixed station. In addition to (here, the fixed station 13), the identification code of the own station and the position of the own station are the identification code of the originating station and the location of the originating station, respectively. It assembles in a search packet and sends it. At this time, the part related to the relay station is undecided.

Then, the mobile station 12 which has received the packet
Checks if it is a packet that it has relayed before, and if it has relayed it, discards it. If the packet is a valid packet, the position of the fixed station 13 is obtained from the fixed station identification code of the packet and the position of the fixed station in the mobile station management table shown in FIG.

Further, a line segment connecting the mobile station 11 and the fixed station 13 is calculated from the position of the fixed station 13 and the position of the transmitting station of the same packet, and the local station in the management table of the mobile station shown in FIG. 3 is calculated. From this position, calculate the distance between this line segment and your own station. Therefore, the mobile station 12 adds “1” to the number of relay stations of the same packet only when this distance is equal to or less than a predetermined value, and adds the identification code of the own station as the identification code of the relay station. Send.

With respect to the other mobile stations that have received the route search packet transmitted from the mobile station 11, it is determined by the same procedure whether or not to relay, and the similar processing is performed before transmission.

FIG. 5 is a diagram showing an example of a fixed station management table of this embodiment. As a result, the fixed station 13 becomes the mobile station 1
Packets that have passed through various routes from 1 arrive, but among those packets, the one with the smallest number of relay stations is selected, and the mobile station 1 in the fixed station management table shown in FIG. 5 is selected.
The number of relay stations and the identification code of the relay station are written in the column 1. Since the identification code of the relay station comes from the mobile station 11, it is written in reverse order in the table.

In the present embodiment, as shown in FIG. 1, assuming that two packets passing through the route 14 and the route 15 arrive, the packet passing through the route 14 having a smaller number of relay stations is adopted. In the mobile station 11 column of the fixed station management table, the number of relay stations is “1”, and the identification code of the relay station is mobile station 1
The identification code of 2 is written.

Finally, the fixed station 13 notifies the mobile station 11 of the number of relay stations up to the mobile station 11 and the identification code of each relay station by using these relay stations, and the mobile station 11 moves them. Write it as route information to the fixed station in the station management table.

The transmission of this route search packet is
Each mobile station periodically performs the data exchange regardless of whether or not it is exchanging data with the fixed station, and both the mobile station and the fixed station keep the latest route information for the data exchange.

[0023]

As described above, the routing method of the present invention has the effect of reducing the number of route search packets circulating in the network and suppressing the decrease in network efficiency due to routing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a relay status of a route search packet according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an arrangement of position information transmitting stations in this embodiment.

FIG. 3 is a diagram showing an example of a mobile station management table in the present embodiment.

FIG. 4 is a diagram showing an example of transmission items of a route search packet of the present embodiment.

FIG. 5 is a diagram showing an example of a fixed station management table of the present embodiment.

[Explanation of symbols]

 11, 12, 22 Mobile station 13 Fixed station 14, 15 Route 21 Position information transmitting station

Claims (1)

[Claims] 1. In a network routing system for performing wireless communication and performing packet exchange between a mobile station and a fixed station by relaying between mobile stations, the location information of the local station is appropriately transmitted and periodically transmitted. Position information transmitting means, means for grasping the position of the own station from the received position information, means for obtaining the identification code of the fixed station closest to the position of the own station, identification code of the fixed station, identification code of the own station , Means for transmitting the position of the local station as a route search packet, means for obtaining the position of the fixed station from the identification code of the fixed station of the packet in the mobile station receiving the packet, and the position of the fixed station and the packet Assuming a line segment that connects the fixed station position and the source station position according to the position of the source station, calculate the distance from the local station and relay the same packet depending on the distance from the line segment. If the distance is smaller than the determined value, it has a means for relaying the packet by adding information to the effect that the local station will relay it, and relays the route search packet. A network routing method characterized by limiting mobile stations that perform communication.