JPH0983528A - Radio network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio network for changing an area where communication is possible without increasing base stations in accordance with the movement of a terminal machine. SOLUTION: A route generation packet where information showing oneself is filled is transmitted to all terminal machines 2 from a base station 1. The terminal machine 2 receiving the packet adds information showing oneself to the packet and transmits it to all the other terminal machines 2. The terminal machine 2 receiving the route generation packet transmits a response packet to a transmission source. The processing is periodically executed and the route of repeated communication between the base station 1 and the respective terminal machines 2 is detected. When the terminal machines 2 cannot directly make mutual communication, data is relayed and transmitted from the transmission source machine to the base station 1 and from the base station 1 to the transmission destination machine in accordance with the detected route.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network composed of a fixed base station and a plurality of movable terminals to perform wireless communication.
The present invention relates to a wireless network that sets a route of relay communication performed when direct communication is impossible according to movement of a terminal.

[0002]

2. Description of the Related Art A conventional wireless network such as a wireless local area network (LAN) is composed of a plurality of base stations, a plurality of wireless terminals, and a wired communication line connecting the base stations, each terminal being a base station. Communication was possible only within the wireless communication range (cell) or direct communication range of the station.

FIG. 20 shows the configuration of a conventional wireless network. The packet transmission from the terminal 2x to the terminal 2y is performed via the base station 1x and the base station 1y as shown in the route r. The packet transmission from the terminal 2z to the terminal 2y is directly performed as shown by the route s. A terminal outside the communication range of the base station 1x or 1y cannot communicate with a terminal that cannot directly communicate.

[0004]

As described above, in the conventional wireless network such as the wireless LAN, the terminals can communicate only in the cell of each base station or in the range where they can directly communicate with each other. In order to secure a possible area, it was necessary to install a base station enough to cover the area with cells, and a large initial investment was required especially when it was necessary to secure a large area. Moreover, when adding or changing the communicable area, it is necessary to add or move a base station, which lacks flexibility.

It is an object of the present invention to realize a wireless network in which a communicable area is changed according to the movement of a terminal without adding a base station.

[0006]

In order to achieve the above object, according to the present invention, a base station that does not move and a plurality of movable terminals are used, and wireless communication is performed between the base station and the terminals and between the terminals. In a wireless network that communicates and relays communication through one or more terminals when direct communication between the base station and the terminals or between the terminals is not possible, the first base station includes information indicating itself. The terminal that has transmitted the packet to all terminals and received the first packet has received the first packet when the received first packet does not have information indicating itself. The first packet that was sent back with the second packet notifying
Information that indicates itself in each packet that is transmitted to all terminals by adding the information indicating itself to each of the packets, and each terminal that receives the first packet transmitted from the terminal indicates itself in the received first packet. When the second packet is not added, the second packet is returned, and information indicating itself is added to the received first packet and transmitted to all terminals, so that between the base station and each terminal. , Which detects a bidirectional communication route, detects this communication route at a predetermined time interval, and each terminal stores the latest detected base station and the communication route between itself and The base station stores the latest detected terminal and a communicable path between itself and relay communication by the stored path.

The terminal receiving the first packet sends the second packet to the terminal or base station which is the direct source of the packet.
When the second packet is returned, the transmission source of the first packet, which has received the second packet, can know that it and the transmission source of the second packet can communicate with each other. . The first packet is transmitted from the base station and is transferred to the other terminals one after another by the terminal that receives it, so that the communication path between the base station and each terminal is established. Since information indicating the base station and the already-received terminal is added to the first packet, each terminal can determine whether or not the first packet received is already received. , If it has already been received, it will not be transferred. This prevents generation of a communication path that circulates through the same terminal twice or more, and avoids wasteful transfer of the first packet.

By detecting this communicable path at a predetermined time interval, a new communication path is established even when the terminal moves. Each terminal stores the route that can communicate with the base station and itself, and the base station stores the route that can communicate with each terminal and itself. Update to the one. By performing the relay communication through the stored route in this way, reliable communication is performed between the base station and each terminal.

Further, it is composed of a base station that does not move and a plurality of mobile terminals that can move. Data is wirelessly transmitted and received between the base station and the terminals and between the terminals, and between the base station and the terminals or between the terminals. In a wireless network that performs relay transmission in which data cannot be transmitted directly between two or more terminals, the base station stores a route for relay transmission from itself to each terminal. In addition, each terminal stores a route capable of relay transmission from itself to the base station, performs relay transmission between the base station and each terminal along the stored route, and And each terminal periodically detects the terminal or base station that can directly transmit from itself and mutually notifies the detection result,
Updates the relay transmission route stored by itself.

In this wireless network, when direct transmission between terminals is not possible, data is transmitted from the source terminal to the destination terminal via the base station. The transmission from the transmission source terminal to the base station and the transmission from the base station to the transmission destination terminal may be direct transmission or relay transmission. Relay transmission from the source terminal to the base station is performed according to the route stored in the source terminal, and relay transmission from the base station to the destination terminal is performed according to the route stored in the base station. Be seen. These stored routes for relay transmission are updated regularly, so even if the terminal moves and relay transmission becomes impossible due to the route up to that point, a new route corresponding to that movement will be used. The relay transmission is surely performed.

In this wireless network, each terminal transmits data to the base station by direct transmission or relay transmission when it cannot directly transmit data to the data transmission destination terminal, and the base station directly receives the received data. The data is sent to the data transmission destination terminal by transmission or relay transmission, and the terminals on the relay transmission path receive it for relay when it can directly transmit to the data transmission destination terminal from itself. The data may be directly transmitted to the data transmission destination terminal.

Each terminal, which serves as a relay in relay transmission, transmits the data received for relay without passing through another relay or base station when it can directly transmit to the data destination terminal. Directly send the data to the destination device. When the direct transmission is not possible, the data is transmitted to the next terminal or base station on the route stored by the terminal or base station that transmitted the data.

In addition, in a wireless network composed of a base station that does not move and a plurality of terminals that can move, and each terminal exists in a wireless network that wirelessly communicates between the base station and the terminals and between the terminals. By sending a packet notifying that the packet is addressed to the base station and all other terminals, and returning the packet notifying that the base station and the terminal receiving this packet have received this packet,
Directly detects whether or not direct communication can be performed between the base station and the terminals and between the terminals, and when data cannot be sent directly between the base station and the terminals or between the terminals, the data is sent directly to each other. Relay transmission is performed to transmit data via a terminal capable of performing.

The terminal which has transmitted the packet notifying that it is present, when receiving the packet returned to notify that the packet has been received, is the terminal or base station which has returned the packet. Know that they can send to each other directly. If this is done regularly, even if the terminal moves, other terminals or base stations that can directly transmit to the moved terminal are detected. Therefore,
When data cannot be directly transmitted between the base station and the terminals or between the terminals, and when relay transmission is performed, the data is transmitted via the terminals that can directly transmit to each other regardless of whether the terminals move or not. It becomes possible to send.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a wireless network of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a wireless network composed of a base station 1 that does not move and a plurality of mobile terminals 2. There is no limit to the number of terminals 2, and FIG. 1 shows a case where there are five terminals 2a to 2e. Communication between the base station 1 and the terminal 2 and between the terminals 2 is performed wirelessly. The area indicated by an ellipse in FIG. 1 represents a range that the radio output of the base station 1 can reach, that is, a cell of the base station 1. The radio output reachable range has a width and shape according to the magnitude and directivity of the output of the base station 1. Terminal 2 existing within this range
a, 2b, and 2d can receive the packet transmitted from the base station 1.

The reach of the wireless output of each terminal 2 has a width and shape according to the size and directivity of the output of each terminal, but here, the terminals connected by arrows in the figure. It is assumed that they can communicate with each other or between the terminal and the base station. For example, in the state of FIG. 1, the terminal 2a can receive the wireless output of the terminal 2c, and conversely, the terminal 2c can receive the wireless output of the terminal 2a.

When the terminals 2 cannot directly communicate with each other, relay communication is performed to transmit data via the base station 1 and other terminals. At this time, the data is transmitted from the source terminal to the base station 1,
It is sent back to and sent to the destination terminal. When the packet is transmitted from the terminal 2c to the terminal 2e, the route p
Then, the packet reaches the terminal 2e via the terminal 2a, the base station 1, and the terminal 2d. In FIG. 1, there is another route q, in which case the terminal 2b is used instead of the terminal 2a.
Will go through. Which of the two routes is used is determined by the processing procedure when the terminal 2c transmits a packet.

The base station 1 stores the communication path from itself to each terminal 2, and each terminal 2 stores the communication path from itself to the base station 1. Each terminal further stores information about other terminals existing near itself. The stored information is updated regularly as the terminal moves. An address for identifying each base station 1 and each terminal device 2, that is, an identification information number is assigned in advance, and this address is written in a packet to be transmitted in order to identify a transmission source and a transmission destination. .

The base station 1 periodically sends a first packet called a route generation packet to all terminals in order to establish a communication path from itself to each terminal 2. The terminal receiving this route generation packet transmits a second packet, which is a route generation response packet, which notifies that the route generation packet has been received, to the base station. Also, the terminal receiving the route generation packet transfers the route generation packet to all the other terminals. The terminal receiving the transferred route generation packet transmits a route generation response packet to the terminal that is the source of the route generation packet.

Each terminal 2 knows the transmission route of the route generation packet from the base station 1 to itself based on the transmission and reception of the route generation packet and the route generation response packet, and the transmission route of the route generation packet is transmitted to the base station under a predetermined condition. A packet called a route update packet for notifying the station is transmitted.

Apart from this, each terminal 2 and base station 1
Sends a packet called a presence notification packet to notify the base station and other terminals that it is present.
The base station or the terminal device receiving this performs a process called a communication confirmation protocol in order to detect whether or not mutual communication with the terminal device that transmitted the presence notification packet is possible.

The configurations of the base station 1 and the terminal 2 as well as the method and processing procedure for establishing a communication path in this embodiment will be described in detail below. FIG. 2 is a block diagram showing a schematic configuration of the base station 1. The base station 1 is connected to a wired communication line 16 to communicate with other base stations (not shown), a wired communication module 11, a wireless module 13 connected to an antenna 15 for wireless packet transmission / reception, a ROM, and A memory device 14 including a RAM for storing programs and various control data, and a processor 12 connected to these devices for performing packet transmission / reception and various control related thereto are provided.

FIG. 3 is a block diagram showing a schematic configuration of the wireless terminal 2. The terminal device 2 includes an input / output device 21 including a key input device for a user interface and a display, a wireless module 23 connected to an antenna 25 for wirelessly transmitting and receiving packets, a ROM and a RAM, programs and various programs. A memory device 24 for storing control data and a processor 22 connected to these devices for controlling input / output, packet transmission / reception and various controls related thereto are provided. Further, first and second timers 27 and 28 are provided so as to be connected to the processor 22.

First, the processing in the terminal 2 will be described. First, the processing of the route generation packet transmitted from the base station 1 at a predetermined time interval will be described. Structures of a route generation packet and a route generation response packet which is a response packet thereof are shown in FIGS. 4 and 5, respectively. The basic structure of the wireless packet in the present embodiment is that the source address, the destination address, and the packet type at the beginning are followed by various data. The structure of the data part after the packet type is defined according to the value of the packet type.

A broadcast address is always set as the destination address of the route generation packet and is transmitted as a broadcast type packet to all terminals. In route generation packets, packet type is followed by packet I
D continues. The packet ID indicates a correspondence relationship between the route generation packet transmitted by the base station 1, its response packet, and a route update packet described later. That is, by confirming that the packet IDs are the same, it is confirmed that the series of response packets and route update packets to be received correspond to one route generation packet transmitted by the base station. It prevents the route generation packet transmitted and the response packet to the route generation packet transmitted by another adjacent base station from being processed by mistake.

The packet ID is followed by a series of route information. The route information consists of the route information length, multiple relay terminal addresses, and base station addresses.When the terminal itself that receives the route generation packet determines that it should operate as a relay terminal, the terminal information Add as a relay terminal address. When the base station first transmits, only the base station address is written and the route information length is 1.

In the route generation response packet, the packet type is followed by the packet ID and the route information update flag. The role of the packet ID is as described above. The route information update flag is for notifying the relay terminal or base station of the response destination that the route to the terminal has been updated.

The structures of base station route information and neighboring terminal information stored in the RAM of the memory device 24 of the terminal 2 are shown in FIGS. 8 and 9, respectively. In the base station route information, a plurality of communication routes from the terminal to the base station 1 are stored, the number of which is described in the number of base station route information at the head. After the number of base station route information, the packet ID of the most recently received route generation packet is stored. A plurality of route information having the same structure as the route information in the route generation packet (FIG. 4) follows the packet ID.

In the near terminal information, information about a plurality of terminals existing in the vicinity of the terminal and information about a base station when the base station exists in the vicinity are stored. The number of stored information is described in the number of neighboring terminal information items at the head. As for each terminal information, the address of the terminal or the base station is recorded at the beginning, and then the communication state is recorded. For this communication state, one of two values indicating "communication enabled" or "communication disabled" is recorded, and only terminal information that is enabled for communication is referred to in the process related to route generation described later. Here, “communication enabled” means that direct transmission is possible in both directions.

As the communication availability confirmation protocol execution time following the communication state, the latest time when the communication availability confirmation protocol is executed is recorded. This value is used in a process related to updating of nearby terminal information described later. The subsequent packet ID and route information update flag are set to values in the process of receiving a route generation response packet from a nearby terminal, and are used in the process related to route generation. The processing regarding these will also be described later.

The processing performed by each terminal 2 when receiving the route generation packet will be described. The process flow is shown in FIG. First, it is checked whether the route information in the route generation packet includes the received address of the terminal itself (step S105). The fact that the route information includes its own address means that the route generation packet looped and arrived again. If the own address is included in this check, the received route generation packet is not processed and discarded.

When the own address is not included, it is checked whether or not the value of the route information length in the route generation packet has reached the preset maximum value (S110). This predetermined maximum value prevents the route to the base station from being generated for an indefinitely long time, and the processing capability of the base station 1 and the terminal 2, the size of the cell of the base station 1, and the number of cells in the cell. It is set to an appropriate value in consideration of the density of the terminals 2 existing in the. If the route information length is the predetermined maximum value in this check, the route generation packet is not processed and is discarded.

By checking the steps S105 and S110, it is possible to prevent the route generation packet from being continuously transferred infinitely, and it is possible to suppress an increase in the communication amount due to the route generation packet and its response packet.

When the route generation packet is not discarded in the check in step S110, that is, when the value of the route information length is less than the predetermined maximum value, another 1 is added.
Two checks are performed (S115). The terminal 2 searches the nearby terminal information in the RAM with the source address of the route generation packet and checks whether the source base station or terminal is recorded as communicable. If the result is that communication is not possible, the route generation packet is not processed and is discarded. By this check, it is possible to prevent a transmission error from occurring frequently due to the formation of a route that cannot actually communicate.

After passing the above check, the R of the terminal is
The base station route information stored in the AM is compared with the information in the received route generation packet. If the packet IDs are different, it is determined that the base station route information needs to be updated regardless of other conditions. If the packet IDs match, the contents of the route information are compared. If the base station route information does not have the same route information as the route information in the route generation packet and the number of base station route information has not reached the maximum value, it is determined that the base station route information needs to be updated (S120). ).

If the base station route information needs to be updated in the check in step S120, the base station route information is updated (S125). At this time, if the packet ID in the received route generation packet and the packet ID in the base station route information are different, the packet I in the base station route information is
D is updated, the stored information is stored in another memory area, the route information in the received route generation packet is stored in the base station route information, and the number of base station route information is set to 1
Set to. As a result, the old route information is deleted from the base station route information, and the possibility of transmitting a packet on a route that cannot be used due to the movement of the terminal is reduced. If the packet IDs match, the route information in the route generation packet is added to the end of the base station route information, and 1 is added to the number of base station route information.

Then, a response packet to the received route generation packet is created and transmitted (S130). The structure of the route generation response packet is as shown in FIG. 5. The source address is set to the address of the terminal itself, and the destination address is set to the source address of the route generation packet. For the packet ID, the same value as the packet ID in the received route generation packet is set. The route information update flag is set to "ON" when the base station route information is updated in step S125 and the updated information is not the same as the corresponding route information in the stored old route information. If it is not set to "OFF".

By creating and transmitting such a route generation response packet, the fact that the route generation packet has been received and processed by the base station or terminal which has transmitted the route generation packet is stored in the base station. Yes, it notifies whether or not it is necessary to update the route information to the terminal that transmitted this route generation response packet.

Finally, the first timer 27 is set and started (S135). This process is step S13.
It is performed following 0, and is performed when a series of route generation packet processing is performed. This first timer 27
Is for obtaining the timing of route generation packet transfer described later. If the first timer is already running, restart the first timer. However, if the route generation packet having the same packet ID has already been transferred, the first timer is not operated.
This is to prevent the route generation packet from being transferred twice.

Next, the processing performed by each terminal 2 for monitoring the route generation response packet will be described. FIG. 12 shows the flow of the processing. This process is performed in parallel with the above-described route generation packet reception process shown in FIG.

First, the processing of the terminal 2 when receiving the route generation response packet will be described. The terminal receives and processes the route generation response packet regardless of whether or not the destination address is its own address. Upon receiving the route generation response packet, the terminal stores the packet ID in the information area of the corresponding terminal in the nearby terminal information in its RAM. Further, the destination address in the received route generation response packet is its own address (that is, this response packet is a response to the route generation packet transferred by the terminal itself), and the route information update flag in the packet is When it is on, the route information update flag of the corresponding terminal in the nearby terminal information is turned on. In other cases, the route information update flag is recorded as off (step S205).

Next, the terminal refers to the neighboring terminal information stored in the RAM, and checks whether the packet IDs of the information for all the neighboring terminals that are in communication are updated to the latest ones. By checking, it is checked whether route generation response packets have been received from all neighboring terminals (S210). If the route generation response packet has not been received from all the neighboring terminals, the following process is not performed and the route generation response packet reception process ends.
Also, when both the first and second timers 27 and 28 are not operating, the reception processing of the route generation response packet ends. When both timers 27 and 28 are not operating, unnecessary route update packets are transmitted when route generation packet reception processing has not been performed or a series of processing has already been completed. It is intended to prevent being abused.

When the route generation response packet is received from all the nearby terminals, it indicates the end of the route generation processing centered on this terminal, and as a subsequent processing, the first and second timers 27 and 28 are released. (S21
5). If the route information update flag of any terminal in the nearby terminal information is ON, a route update packet is created and transmitted (S220). If there is no terminal whose storage of the route information update flag is on, transmission of the route update packet is not necessary.

The structure of the route update packet is shown in FIG.
The address of the terminal itself is set as the source address of the route update packet, and the address of the first relay terminal or base station stored in the first route information in the base station route information is set as the destination address. Set a code indicating "route update" to the packet type and set the packet ID.
Sets the value of the packet ID in the nearby terminal information. Following that, the routing information is set. The contents of the first route information (route information 1 in FIG. 8) of the base station route information are set as they are in the routing information. As a result, the final base station address in the route information 1 is set at the position of the final final destination terminal address in the routing information.

The route update information is followed by the route update terminal information. At the top of the route update terminal information, a route update terminal information length indicating the number of terminals that have updated the route is set, followed by a plurality of route update terminal addresses. For this purpose, the address of the terminal for which the route information update flag of the nearby terminal information in the RAM of the terminal is turned on is set.

Next, the processing for the timeout of the first timer 27 will be described (FIG. 12). The timeout of the first timer indicates that there is a terminal which has not received the route generation packet among the terminals near this terminal. In order to establish a route to those terminals, a route generation packet having route information in which its own address is added as the first relay terminal address (relay terminal address 1) to the route information 1 in the base station route information of the RAM. Is created and transmitted to all terminals (S22
5). However, when the route information length of the route information 1 in the base station route information has reached the maximum value, the transfer process of this route generation packet is not performed. This is to prevent the route from being infinitely extended and causing the route generation process to diverge.

Then, the second timer 28 is set and started (S230). This is to obtain the transmission timing of the route update packet when the route generation response packet cannot be received from all the neighboring terminals due to the movement of the terminal or the like.

The processing for the timeout of the second timer 28 will be described. The second timer timeout is
It indicates that no response could be obtained from all the neighboring terminals even after the route generation packet was transferred by this terminal. When the second timer times out, the terminal creates and transmits a route update packet for the terminal that has received the route generation response packet up to that point, as in step S220 (S235). In this way, by transmitting the route update information for a plurality of terminals in one packet, it is possible to keep the communication volume related to the route generation low.

Next, the procedure for updating the neighboring terminal information for each terminal 2 and base station 1 included in the above description of the route generation procedure will be described. In order to do this, the base station 1 and each terminal 2 send a presence notification packet to all terminals and base stations at regular time intervals. FIG. 13 shows a process of updating neighboring terminal information performed by the terminal when the presence notification packet is received.

When the terminal receives the presence notification packet, first, it is checked whether the terminal or the base station indicated by the source address of the presence notification packet is recorded as communicable in its own nearby terminal information. Yes (step S305). If communication is already recorded, it is not necessary to perform the subsequent processing, so the processing ends. If the communication is not recorded as possible, then it is checked whether or not the source terminal device or base station is recorded as communication disabled in its own nearby terminal information (S310).

If the communication is recorded as not possible, it is further checked whether or not a predetermined time has passed since the previous communication availability confirmation protocol was executed for the terminal or base station (S315). Step S31
If the predetermined time has not elapsed in the check of 5, the reception processing of the presence notification packet is ended. It is possible to prevent an increase in communication volume by not executing the communication availability confirmation protocol described below when the predetermined time has not elapsed.

As a result of the checks in steps S310 and S315, the terminal or base station which is the transmission source of the presence notification packet is not recorded in the nearby terminal information, or it is recorded as communication disabled and the previous communication is possible. If the specified time has passed since the confirmation protocol was executed,
The communication availability confirmation protocol is executed for the terminal or base station that is the source of the presence notification packet (S32).
0).

FIG. 19 shows the procedure of the communication availability confirmation protocol. The terminal that receives the presence notification packet becomes the confirmation wireless terminal, and the terminal or base station that transmits the presence notification packet becomes the confirmed wireless terminal, and the communication availability confirmation packet is sent from the confirmation wireless terminal to the confirmed wireless terminal. Send. The wireless terminal to be confirmed, which has received the communication availability confirmation packet, transmits a communication availability confirmation response packet notifying the reception to the confirmation wireless terminal. By executing the communication confirmation protocol, it is possible to confirm whether or not the two terminals or the terminal and the base station can directly communicate in both directions.

Thereafter, the execution result of the communication availability confirmation protocol is checked (S325), the current time is recorded at the communication availability confirmation protocol execution time, and whether communication is possible or not is stored in the nearby terminal information. It is recorded in the communication state of the corresponding terminal information (S330, S335). In the information about the terminal or base station that has transmitted the presence notification packet in the neighboring terminal information, the information of that portion is updated if it already exists, and is newly added if it does not exist.

In addition to the reception processing of the presence notification packet, the nearby terminal information is checked at regular intervals, and the terminal information for which the difference between the communication availability confirmation protocol execution time and the current time is a predetermined value or more is checked. Perform processing. With respect to the terminal information for which the time has passed while the communication is not possible, the deletion processing is performed. This prevents the information of terminals or base stations that are no longer in the vicinity from remaining in the RAM. In addition, for terminal information for which time has elapsed in the communication enabled state, the communication availability confirmation protocol is executed to reconfirm that communication is possible. As a result, if the communication is possible, the communication availability confirmation protocol execution time in the terminal information is updated, and if the communication is not possible, the terminal information is deleted.

As described above, by performing the processing relating to the reception of the presence notification packet on the presence notification packet transmitted to each of the surrounding terminals or base stations, the neighboring terminal information is updated, and each terminal is It becomes possible to always grasp the terminals or base stations existing in the vicinity. As a result, each terminal can accurately perform the above-described processing for generating a route that passes through a peripheral terminal or that is directed from the base station to a peripheral terminal, and dynamic route generation is possible. It will be possible.

Next, a procedure and a data packet structure relating to transmission of data packets exchanged between the terminals 2 in the wireless network of the present invention will be described. FIG. 7 shows the structure of the data packet. The source address is set to the address of the terminal that first created and sent the data packet, and is not rewritten even when relayed by a relay terminal or base station. The address of the terminal or base station that directly receives the packet is set as the destination address. Therefore, the destination address is rewritten each time it is relayed to the address of the terminal or base station to be received next.

The type of packet is "data". The subsequent downlink transmission flag is for identifying whether the data transmission is from the terminal to the base station or the data transmission from the base station to the terminal. The downlink transmission flag is set to off when the terminal first transmits the data packet, and changed to on when the base station relays the data packet. This downlink transmission flag is used in error recovery processing of communication from the base station to the terminal.

The downlink transmission flag is followed by a series of routing information. The routing information is composed of a route information length, a plurality of relay terminal addresses, a base station address and a final destination terminal address, and indicates a route through which a data packet is relayed. The routing information is updated when the data packet is relayed at the base station. The base station address is not included in the routing information updated by the base station. The routing information is followed by communication data composed of data length and data content.

FIG. 14 shows the flow of processing when the terminal 2 transmits a data packet. The terminal secures a memory area required for a data packet including routing information when transmitting data, and creates a data packet without routing information (step S405). This will write your own address as the source address,
A ready-to-send data packet is generated with the address of the final destination terminal, which is the destination of the data, as the destination address.

Next, the near terminal information stored in the RAM is searched by the address of the final destination terminal, and it is checked whether or not the final destination terminal is recorded as communication enabled (S410). If the final receiving terminal is not recorded as communication-enabled in this check, the route information 1 (FIG. 8) is read from the base station route information in the RAM and set in the data packet. Further, the destination address of the data packet is set to the relay terminal address 1 in the route information 1 above.
To update (S415). After the data packet is updated in step S415, or if the final destination terminal is recorded as communication enabled in step S410, the data packet is transmitted (S420).

By the processing of steps S410 to S420, the data packet is directly transmitted to the nearby terminals that can communicate directly, and the route information to the base station is added to the terminals that cannot communicate directly. After that, the data packet is transmitted to the appropriate relay terminal.

Next, a description will be given of the processing performed when the terminal 2 receives a data packet with routing information or a route update packet and the final destination terminal needs to transfer the packet instead of itself. The process flow at this time is shown in FIG.

When the terminal receives the data packet with the routing information or the route update packet transmitted to itself, the terminal searches the nearby terminal information in the RAM with the final destination terminal address in the received packet, and It is checked whether the terminal indicated by the called terminal address is recorded as communication enabled (step S505). With this check, if the final destination terminal is recorded in the nearby terminal information as communicable, it is possible to directly communicate with the final destination terminal, so the final destination terminal address in the packet is set to the destination address. Set (S510).

If the final destination terminal is not able to communicate in the check of step S505, it searches for its own address in the routing information of the packet, and the address of the next relay terminal or base station set next to it. Take out. Then, the near terminal information is searched for by the address of the relay terminal or the base station, and it is checked whether or not the near terminal information is recorded as communication enabled (S515). In this check, if the relay terminal or base station, which is the next destination, cannot communicate, the process shown in FIG. 16 is performed as a transmission error. If the next destination relay terminal or base station is communicable, the address is noted in the destination address of the received packet (S520). That is, the destination address is updated with the address of the next relay terminal or base station included in the routing information of the received packet.

Finally, step S510 or S520
In step S52, the data packet or the route update packet in which the destination address is updated is transmitted for forwarding.
5). When the process of step S520 is performed, the relay transmission according to the routing information set by the terminal that created and transmitted the data is continued, and step S5
When the process of 10 is performed, the relay transmission according to the routing information is stopped, and the transmission is performed by short-circuiting to the final destination terminal which is the destination of the data.

Next, a description will be given of the processing in the case where an error occurs that the source terminal and the destination terminal cannot communicate with each other when the data packet or the route update packet is transmitted due to the movement of the terminal 2 or the like. To do. FIG. 16 shows the flow of processing performed by the terminal device of the transmission source at this time. The terminal is
If a transmission error occurs in the check of the nearby terminal information in step S515 of FIG. 15, or if there is no response to the destination terminal in the physical layer transmission processing in the wireless module 23 that has received the packet transmission request, the destination terminal device When a transmission error occurs due to the inability to communicate with, the processing of FIG. 16 is performed.

At this time, the terminal compares the base station route information in the RAM with the routing information in the packet having the transmission error, and if the route information different from the routing information in the packet exists in the base station route information. , Set it in the routing information of the packet. If the route information different from the routing information in the packet does not exist in the base station route information, the terminal address that can be communicated with and is different from that of the receiving terminal that has the transmission error is fetched from the nearby terminal information in RAM, and the terminal address Is set in the routing information in the packet as a substitute for the terminal address in which the transmission error occurred (step S605).

Next, the routing information in the packet updated in step S605 is searched for by its own address. If the own address does not exist, it is the first relay terminal address in the routing information, and if its own address exists. The destination address is updated with the relay terminal address next to its own address (S610). Finally, the packet with the updated destination address is transmitted (S61).
5).

As described above, when a data packet is transmitted to a partner terminal which cannot directly communicate with the other terminal, the routing information is added and transmitted to the communicable relay terminal. By appropriately transferring packets based on this, communication between terminals becomes possible in a wide area not restricted by the communicable range of the base station. Further, the route update packet described above is relayed similarly to the data packet, and finally reaches the base station.

The terminal route information data stored in the RAM of the memory device 14 by the base station 1 will be described. FIG. 10 shows the structure of the terminal route information data. The terminal route information data is composed of route information for a plurality of terminals 2. The route information for each terminal has a terminal address at the beginning, followed by two route information. Each route information has the same structure as the route information in the base station route information stored in the terminal shown in FIG. 8, except that the last base station address is not included. Incidentally, the route information when the terminal, which is the shortest route information, is capable of direct communication, is the route information having only the route information length of 0. By setting the route information length to a value larger than the predetermined maximum value of the route information, it can be shown that the route information is not recorded.

Here, as shown in FIG.
Up to two pieces of route information can be stored for each terminal, but the number of pieces of route information that can be stored for each terminal is not limited to two, and more route information can be stored. May be stored. The number is set in consideration of the cell size of the base station, the number of terminals, etc. so that the wireless network can function efficiently.

A process related to route generation in the base station 1 will be described. The base station transmits a route generation packet at a predetermined time interval to activate a series of route generation processing. The packet ID of the route generation packet transmitted from the base station is set to a different value every time. As described above, the route generation packet is sequentially transferred to another terminal by the receiving terminal and used for forming a route to the base station of each terminal. A plurality of route update packets and a plurality of route generation response packets are returned from the terminal to the base station.

FIG. 17 shows the flow of processing performed by the base station 1 when it receives a route update packet or a route generation response packet. In the case of a terminal, all route generation response packets were received and processed regardless of the destination address, but the base station processes only packets whose destination address is its own address. First, it is checked whether or not the value of the packet ID in the received route update packet or the route generation response packet matches the value of the packet ID set in the most recently transmitted route generation packet (step S705). ).

If the packet ID values match in this check, the base station updates the terminal route information in the RAM with the information in the received route update packet or route generation response packet (S710). Specifically, when the received packet is a route update packet, the terminal route information data stored at a plurality of route update terminal addresses included in the route update terminal information (FIG. 6) in the received packet is searched, The terminal route information corresponding to each terminal is updated or added. When the received packet is a route generation response packet, the terminal route information data stored at the source address of the received packet is searched and the corresponding terminal route information is updated or added.

In updating or adding terminal route information, if the received packet is a route update packet, the routing information is extracted from the received packet, and the final final destination terminal address (base station address) is removed from the routing information. The reverse order of the relay terminal addresses is processed as updated route information to the terminal route information in the RAM. When the received packet is a route generation response packet, the route information having only the route information length of 0 is processed as the updated route information for the terminal route information. The relay terminal addresses of the update route information are rearranged in the reverse order because the base station uses the route information as directed to the terminal, so the routing information in the route update packet set as the route information to the base station is used. Is because the directions are opposite.

As a result of searching the terminal route information in the RAM, if the corresponding terminal route information does not exist, the searched terminal address is set in the terminal address and the updated route information is set as the first route information (route information N). -1) Add the terminal route information set in (FIG. 8). When the corresponding terminal route information exists, if the subsequent route information (route information N-2) exists, the route information N-1 is updated with that information, and then the updated route information is updated to the route information N.
Set to -2.

As described above, since the terminal route information is updated in response to the reception of the route update packet or the route generation response packet, the base station can always hold the latest route information for the terminal.

Finally, the processing when the base station 1 receives a data packet containing routing information will be described. The flow of processing at this time is shown in FIG. This processing is performed when the base station holds the terminal route information corresponding to the final destination terminal address in the received data packet in its own RAM. If the corresponding terminal route information is not held, processing such as transfer to another wireless base station that can communicate with the target final destination terminal will be performed. Details of those processes are omitted because they are outside the scope of the present invention.

When the base station receives a data packet with routing information that needs to be transferred to the terminal, it first checks the value of the downlink transmission flag in the packet (step S805). As a result, if it is ON, it means that the data packet already transferred to the terminal has been returned to the base station due to a transmission error in the middle of the route. Therefore, the processing corresponding to the transmission error from step S825 is performed. Proceed to.

If the downlink transmission flag is off, the following data packet transfer processing is performed. First, the terminal route information data in the RAM is searched by the final destination terminal address included in the routing information in the received data packet, and the first route information (route information N-1) is taken out. Then, of the route information in the routing information of the received data packet, the portion before the final destination terminal address is updated with the extracted route information (S810). Next, the destination address of the data packet is updated with the first relay terminal address (relay terminal address 1) of the routing information in the updated data packet, or the final destination terminal address if there is no relay terminal address ( S815).

After that, the downlink transmission flag in the data packet is set to ON, and the data packet is transmitted (S820). Through these processes, the received data packet has its routing information and destination address updated, the downlink transmission flag turned on, and the data packet changed from the base station to the final destination terminal. , Will be sent back.

After that, the data packet is relayed and transmitted while being subjected to the same processing as the transfer of the data packet in the relay terminal device as described above, and finally reaches the intended final destination terminal device. To do. Even in relay transmission from the base station to the final destination terminal, the relay terminal
When it is possible to directly transmit to the final destination terminal from itself, the data packet is directly transmitted to the final destination terminal.

When the downlink transmission flag of the data packet received in the check in step S805 is ON, the base station tries to retransmit by a route different from the route used in the previous transmission. First, the stored terminal route information data is searched for by the final destination terminal address of the received data packet, and it is determined whether or not the second route information (route information N-2) is present in the corresponding terminal route information. Check (S825). If route information N-2 exists, the first route information in which the error occurred (route information N-1)
Is overwritten with the contents of the route information N-2, and the route information N-
A parameter without information is set in 2 (S83
0). Then, the process proceeds to the data packet transfer process after step S810 already described.

By the above processing, the first route information in which an error has occurred is erased, and the data packet is retransmitted with new routing information set. This retransmission process increases the probability that the data packet will reach the final destination terminal.

On the other hand, the second check is made in step S825.
If the route information of No. does not exist, the terminal route information obtained as a result of the check, that is, the terminal route information corresponding to the final destination terminal address in the received data packet is deleted from the terminal route information data in the RAM (S).
835). By this processing, the terminal route information in which a transmission error has occurred is deleted promptly, so that the routing information in which an error occurs will not be added and transferred to the data packet that is subsequently received, and the increase in communication volume due to an error occurrence will be suppressed. be able to.

As described above, the relay communication in the present invention is performed from each terminal 2 to the base station 1 and from the base station 1 to each terminal 2, and each route is It is stored in the terminal 2 and the base station 1.
Relay communication from each terminal 2 to another terminal 2 is not intended. This is to keep the required storage capacity of the memory device 24 of each terminal device 2 small and to simplify the route generation process as much as possible to suppress an increase in communication volume accompanying the route generation process.

If each terminal 2 stores the route of relay communication to all other terminals 2 other than the base station 1, the efficiency at the time of communication may be improved. A large storage capacity is required, and the inconvenience of increasing the communication amount for route generation occurs. In particular, the amount of communication for route generation is approximately proportional to the square of the number of terminals 2, and the larger the network, the greater the load on the network for route generation. The communication efficiency of the entire wireless network is reduced.

In the wireless network of the present invention, reliable relay communication can be performed, and the route generation process for relay communication is simple. Therefore, it is possible to construct a large-scale network as well as a small-scale network without being affected by the number of terminals 2.

[0090]

According to the wireless network of the present invention, a route capable of surely performing bidirectional relay communication between the base station and each terminal is detected. Therefore, when direct communication cannot be performed, detection is performed. Relay communication can be reliably performed by the relay route thus established. Since the terminal relays between the base station and the terminal, even a terminal located outside the cell of the base station can communicate with the base station by relay communication. By performing relay communication via this base station, it becomes possible to communicate between terminals that cannot communicate directly.

Moreover, since the relay communication route is updated at predetermined time intervals, even if the relay communication route is interrupted due to the movement of the terminal, a new relay communication possible route is detected. Therefore, even when the terminal frequently moves, it is possible to find a relay communication route corresponding to the movement. Further, since the same terminal does not retransmit the first packet transmitted for route detection of relay communication, the increase in communication amount for route detection can be suppressed to a low level, which improves the communication efficiency of the wireless network. It never drops.

In the wireless network according to the second aspect, when direct transmission is not possible between the terminals, the transmission is performed from the transmission source terminal to the transmission destination terminal once via the base station. Does not need to store the route of relay transmission to all the other terminals, and needs only to store the route of relay transmission to the base station. Therefore, the amount of information stored in each terminal can be kept small, and relay transmission can be performed by a small-capacity storage device. In addition, even if the terminal is located outside the cell of the base station, it is possible to communicate with the base station by relay communication. It is also possible to send. Since the relay transmission route stored in the base station and each terminal is periodically updated, even if the terminal moves, the relay transmission can be surely performed by the new route capable of relay transmission.

According to the wireless network of claim 3, a reliable transmission route from the data transmission source terminal to the base station even when the data transmission source terminal cannot directly transmit to the data transmission destination terminal. By transmitting the data along the reliable transmission path from the base station to the data transmission destination terminal, the data transmission can be surely performed. Moreover, when data transmission from the data transmission source terminal to the base station or from the base station to the data transmission destination terminal is performed by relay transmission, the direct transmission is performed when it is possible to directly transmit from the relay terminal to the data transmission destination terminal. Therefore, the data transmission destination device can receive the data promptly and can reduce the communication amount, so that the communication efficiency of the wireless network is improved.

In the wireless network according to claim 4, by transmitting the packet notifying the existence of itself and the packet notifying that the packet has been received, direct communication between the terminals and between the terminal and the base station is performed. Whether it is possible or not is surely detected. In addition, since the detection of the availability of the direct communication is performed not once but periodically, the availability of the direct communication after the movement is detected even when the terminal moves. Since the relay communication is performed via the terminals that are detected to be able to directly communicate with each other in this way, it is possible to reliably perform communication even between the terminals that cannot directly communicate with each other.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a wireless network of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a base station.

FIG. 3 is a block diagram showing a schematic configuration of a terminal.

FIG. 4 is a diagram showing a structure of a route generation packet.

FIG. 5 is a diagram showing a structure of a route generation response packet.

FIG. 6 is a diagram showing a structure of a route update packet.

FIG. 7 is a diagram showing the structure of a data packet.

FIG. 8 is a diagram showing a structure of base station route information stored in a terminal.

FIG. 9 is a diagram showing a structure of nearby terminal information stored in a terminal.

FIG. 10 is a diagram showing a structure of terminal route information stored in a base station.

FIG. 11 is a flowchart showing a process when the terminal receives a route generation packet.

FIG. 12 is a flowchart showing a process when the terminal receives a route generation response packet.

FIG. 13 is a flowchart showing processing when a terminal presence notification packet is received.

FIG. 14 is a flowchart showing a process when a terminal sends a data packet.

FIG. 15 is a flowchart showing a process when the terminal receives a data packet or a route update packet.

FIG. 16 is a flowchart showing processing when a transmission error occurs in the terminal.

FIG. 17 is a flowchart showing a process when a base station receives a route update packet or a route generation response packet.

FIG. 18 is a flowchart showing processing when a base station receives a data packet.

FIG. 19 is a diagram showing a communication availability confirmation protocol.

FIG. 20 is a diagram showing a configuration of a conventional wireless network.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base station 2, 2a-2e Terminal 11 Wired communication module 12 Processor 13 Wireless module 14 Memory device 15 Antenna 16 Wired communication line 21 Input / output device 22 Processor 23 Wireless module 24 Memory device 25 Antenna 27, 28 Timer

Claims (4)

[Claims] 1. A base station that does not move and a plurality of terminals that can move, and wirelessly communicates between the base station and the terminals and between the terminals, and directly between the base station and the terminals or between the terminals. In a wireless network that performs relay communication through one or more terminals when communication is not possible, a base station transmits a first packet including information indicating itself to all terminals, and the first packet is transmitted. When the terminal receiving the packet returns the second packet notifying that the first packet has been received when the information indicating itself has not been added to the received first packet, The information indicating itself is added to one packet and transmitted to all terminals, and each terminal receiving the first packet transmitted from the terminal identifies itself to the received first packet. Indication When the information is not added, the second packet is returned and the information indicating itself is added to the received first packet and transmitted to all the terminals, so that the base station and each terminal Detects a bidirectional communication path between machines, detects the communication path at a predetermined time interval,
Each terminal stores the latest communication path between itself and the detected base station, and the base station stores the latest communication path between itself and each detected terminal, depending on the stored path. A wireless network characterized by relay communication. 2. A base station that does not move and a plurality of terminals that can move. Data is transmitted and received wirelessly between the base station and the terminals and between the terminals, and between the base station and the terminals or between the terminals. When data cannot be sent directly between
In a wireless network that performs relay transmission by transmitting via one or more terminals, a base station stores a route for relay transmission from itself to each terminal, and each terminal stores the base station from itself. The route that can be relayed to the terminal is stored, and the relay transmission is performed between the base station and each terminal along the stored route, and the base station and each terminal directly transmit from themselves. A wireless network which detects a terminal or a base station capable of performing wireless communication, periodically notifies each other of the detection results, and updates the relay transmission route stored in itself. 3. Each terminal transmits data to the base station by direct transmission or relay transmission when the data cannot be directly transmitted to the data transmission destination terminal, and the base station directly transmits or relays the received data. The data transmitted to the data transmission destination terminal by transmission, and the terminals on the relay transmission path are the data received for the relay when they can directly transmit to the data transmission destination terminal from themselves. The wireless network according to claim 2, wherein the data is directly transmitted to the data destination terminal. 4. In a wireless network composed of a base station that does not move and a plurality of terminals that can move, and each terminal exists in a wireless network that wirelessly communicates between the base station and the terminals and between the terminals. By sending a packet notifying that the packet is addressed to the base station and all other terminals, and returning the packet notifying that the base station that received the packet and the terminal received the packet, It periodically detects whether or not direct communication between terminals and terminals can be performed, and when data cannot be sent directly between the base station and terminals or between terminals, mutual transmission is possible. A wireless network characterized by performing relay transmission for transmitting data via a terminal.