JP2007336101A - Radio communication apparatus and message transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus and a message transmission method capable of efficiently relaying a message at a narrow band digital wireless communication system, regardless of situation in wireless environment and the length of the message. <P>SOLUTION: The radio communication apparatus comprises a radio transmitter/receiver 4 for transmitting and receiving wireless data; a holder 12 for holding data, an other node information write-in 21 capable of writing a location information of other node received by the radio transmitter/receiver 4 into the holder 12; an own node information acquiring portion 2 for acquiring a location information of the own node; and a message transmission stop portion 23 for computing the distance between a location information of a destination node held at the holder 12 and a location information of the own node, acquired by the own node information acquiring portion 2 and stopping transmission of a message based on the distance and a distance threshold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus suitable for use in, for example, a digital wireless communication system and a message transmission method usable for the wireless communication apparatus.

  A digital wireless communication system wireless communication apparatus normally disassembles (fragments) a message to be transmitted into a plurality of small pieces, packetizes each small piece, and transmits and receives all packets in packet units. If there is at least one packet lost in the radio propagation process, a packet that cannot be recovered by means of correcting a lost packet, or a packet that contains an error that cannot be corrected using an error correction code, etc., the wireless communication device It is determined that the entire reception has failed.

  When the transmission band is a narrow band such as several thousand bits / second, the code length for error correction is limited. In an environment where the quality of the communication channel is poor, there are cases where error correction cannot be performed sufficiently.

  In addition, when a plurality of wireless communication devices are also configured as nodes (communication nodes) that relay packets, packets are likely to be lost during relay due to congestion in each node, particularly when the bandwidth is narrow.

  From the viewpoint of radio wave utilization efficiency, sending a long message to a destination node that is far away and has many relays causes a waste of bandwidth.

  For this reason, particularly in a narrowband digital wireless communication system, it may be effective for a node to implement a mechanism or means for canceling transmission of a long message to a remote destination node.

As a function for performing this cancellation, for example, a method that uses TTL (Time To Live) is known (see, for example, Patent Document 1). This TTL corresponds to the valid period of the packet, and the initial value of the packet is reduced every time it passes through the node. Each node refers to a field such as TTL included in the received packet, and discards the packet as a packet having a large number of relay stages when the TTL is smaller than a preset value.
JP 2001-309201 A

  However, in a narrow-band communication system, even if TTL is used, each node performs transmission / reception processing of all packets regardless of the length of the message. Therefore, when a packet is received, a long message packet causes congestion. There are many cases. Furthermore, a node that transmits a packet cannot confirm whether the transmitted packet has been transferred or discarded at a subsequent node. Also, it is generally difficult to provide a transfer or discard confirmation mechanism for all nodes.

  Therefore, in view of the above problems, the present invention provides a wireless communication apparatus and a message transmission method capable of efficiently relaying a message in a narrow-band digital wireless communication system regardless of the wireless environment and the length of the message. The purpose is to provide.

  According to an aspect of the present invention, a wireless transmission / reception unit that transmits / receives wireless data, an other node information writing unit that can write position information of another node received by the wireless transmission / reception unit in a holding unit that holds data, Calculates the distance between the local node information acquisition unit that acquires the positional information of the node, the positional information of the transmission destination node held in the holding unit, and the positional information of the local node acquired by the local node information acquisition unit And a message transmission stop unit that stops the transmission of the message based on the distance and the distance threshold.

  According to an aspect of the present invention, there is provided a message transmission method in a transmission source node that transmits / receives wireless data to / from a plurality of nodes, the transmission source node acquiring position information of the transmission source node, and the transmission The source node multicasting the acquired location information of the source node; and the location of the other node from the other node from which the source node received the location information of the source node of the plurality of nodes. Receiving the information; comparing the length of the message to be transmitted by the transmission source node with a predetermined length; and when the transmission source node is longer than the predetermined length of the message, Calculating a distance between the position information of another node and the position information of the transmission source node; and If you have a message transmission method characterized by comprising the step of stopping transmission of said message to said another node is provided.

  According to the present invention, each node transmits a long message destined for a remote destination node that is unlikely to reach a destination node and that may interfere with other communication processing in the message transmission process. The message can be canceled and the message can be transmitted effectively, and the packet transfer efficiency can be improved.

  Hereinafter, a wireless communication apparatus according to an embodiment of the present invention and a message transmission method used for the wireless communication apparatus will be described with reference to the drawings. In the drawings, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  A node according to an embodiment of the present invention is a movable wireless device that wirelessly transmits and receives packets, and is configured as a node that joins a digital wireless communication system, and can be identified by, for example, an IP (Internet Protocol) address It is.

  As shown in FIG. 1, each node includes a terminal 1, a GPS (Global Positioning System) receiving unit 2, a communication control unit 3, a wireless transmitting / receiving unit 4, and LANs (Local Area Networks) 5, 6 And a serial cable 7.

  Here, the terminal 1 creates a packet including a transmission message and extracts a message from a packet received from another node of the communication partner.

  The GPS receiving unit 2 is a local node information acquisition unit that acquires positional information of the local node. This GPS receiver 2 outputs the latitude data and longitude data of its own node by GPS.

  The communication control unit 3 controls communication with each unit in the wireless communication apparatus and other nodes, and between the length of the transmission message and the own node and other nodes (hereinafter referred to as other nodes). Message filtering processing is performed based on the distance.

  The wireless transmission / reception unit 4 transmits / receives wireless data. The wireless transmission / reception unit 4 wirelessly transmits a packet created by the terminal 1 to another node and demodulates a wireless signal from the other node to generate a reception packet. The wireless transmission / reception unit 4 periodically multicasts the position information of its own node.

  The LAN 5 connects between the terminal 1, the communication control unit 3, and the wireless transmission / reception unit 4, and the LAN 6 connects between the communication control unit 3 and the wireless transmission / reception unit 4. It is. The serial cable 7 connects between the communication control unit 3 and the GPS receiving unit 2.

  Thereby, the communication control unit 3 decomposes the message from the terminal 1 to generate a plurality of packets, wirelessly transmits each packet to the other node, and generates a message from the packet wirelessly received from the other node. Output to terminal 1.

  The communication control unit 3 will be further described in detail. As shown in FIG. 2, the communication control unit 3 includes a GPS receiver interface unit (GPS reception unit interface unit) 10, a self-location information holding unit 11, a location information database 12, a terminal interface unit 8, an encoder 13, and a radio interface. Unit (wireless transmission / reception unit interface unit) 9, decoder 14, control circuit 15, and untransmitted message holding unit 24.

  Here, the GPS receiver interface unit 10 uses the latitude and longitude data output from the GPS receiver 2 to calculate the latitude and longitude of the own node.

  The self-location information holding unit 11 holds the latitude and longitude of the own node calculated by the GPS receiver interface unit 10.

  The position information database 12 is an updatable database and holds data in which the IP address of another node is associated with the latitude and longitude of the other node as position information. The location information database 12 further holds the reception time information in association with the location information. The location information database 12 associates each node's IP address, latitude and longitude, and the reception time with each other, and holds it as a table entry.

  The control circuit 15 calculates the distance between the own node and the other node using the latitude and longitude of the own node and the latitude and longitude of the other node, and calculates the calculated distance and the message length. Multiplication is performed to perform message transmission or stop filtering processing. The control circuit 15 includes an other node information writing unit 21, a message length comparison unit 22, and a message transmission stop unit 23.

  The other node information writing unit 21 writes the position information of the other node received by the wireless transmission / reception unit into the position information database 12.

  The message length comparison unit 22 compares the message length addressed to the transmission destination node with the message length threshold.

  The message transmission stop unit 23 calculates the distance between the position information of the transmission destination node held in the holding unit and the position information of the own node acquired by the own node information acquisition unit, and based on the distance and the distance threshold It stops sending messages. The message transmission stop unit 23 calculates the distance when the message length comparison unit determines that the message length is larger than the message length threshold.

  Specifically, the control circuit 15 can search for the latitude and longitude of another node corresponding to the IP address using the IP address as a search key. Here, assuming that the distance calculated from the latitude and longitude is a (meter), the transmission message length is b (byte), and the threshold is c (meter / byte), the control circuit 15 satisfies a * b> c. Cancel transmission for the message (* represents multiplication). That is, when either one or both of the distance a and the message length b are large and the multiplication result a * b by the distance a and the message length b exceeds a threshold c set appropriately in advance, the message is transmitted. Is stopped.

  The control circuit 15 commands an operation sequence with other nodes. Then, each node exchanges position information of each node in order to update the distance with another node that varies from time to time. For this reason, the control circuit 15 controls the wireless transmission / reception unit 4 so as to multicast the position information of the own node at regular intervals. At the time of transmission processing, the control circuit 15 writes, as an example, data including a message identifier representing a message type (a magic number described later), latitude, and longitude as position information in a packet to be transmitted.

  Further, the control circuit 15 deletes entry data having a reception time older than a preset time from the position information database 12. When an entry corresponding to the position information database 12 cannot be found, the control circuit 15 determines that communication is not possible (missing state) and sets the distance to the transmission destination node to infinity. That is, the message transmission stop unit 23 calculates the distance as an infinite length when the position information of the destination node is not held in the position information database 12.

  Further, the writing in the other node information writing unit 21 updates the location information of the destination node after the recovery when the communication with the destination node whose transmission is stopped by the message transmission stop unit 23 is recovered.

  The unsent message holding unit 24 holds unsent messages. Then, when the communication with the transmission destination node whose transmission is stopped by the message transmission stop unit 23 is recovered, the wireless transmission / reception unit 4 transmits an untransmitted message to the transmission destination node from the non-transmission message holding unit 24.

  The terminal interface unit 8 performs interface processing such as format conversion for each of the transmission message input from the terminal 1 and the reception message input from the terminal 1.

  The encoder 13 (FIG. 2) decomposes the transmission message processed by the terminal interface unit 8 into a plurality of UDP (User Datagram Protocol) / IP packets. The node 40 according to the present embodiment performs connectionless communication that does not require setting of a logical communication channel, and the encoder 13 transmits a UDP / IP packet 41 shown in FIG. Generate. The UDP / IP packet 41 includes a header area 42 and a user data area 43. A “from” field and a “to” field are secured in the header area 42, and an area called a magic number 16 indicating that the message type is position information is secured in the user data area 43. The decomposed message is stored in the payload 17.

  The radio interface unit 9 outputs the image of the UDP packet generated by the encoder 13 (the entire UDP packet) to the radio transmission / reception unit 4 and also receives the image of the UDP packet from another node received by the radio transmission / reception unit 4 by the decoder 14. Output to.

  Further, as shown in FIG. 3B, the transmission message has fields of an IP address 18, a message length 19, and a message body 20 of the transmission destination node. The transmission message may have other fields as necessary.

  The decoder 14 assembles (assembles) a received message from a plurality of UDP / IP packets transmitted by other nodes.

  As a result, the wireless communication apparatus according to the present embodiment can perform communication without being aware of whether or not the data transmitted by the wireless communication apparatus itself has arrived at the other node without confirming the response from the other node.

  The self-location information holding unit 11, the location information database 12, and the unsent message holding unit 24 may be provided outside the communication control unit 3, or may be configured to be removable from the node body. .

  The GPS receiver interface unit 10, the terminal interface unit 8, the encoder 13, the radio interface unit 9, the decoder 14, and the control circuit 15 all have a CPU (Central Processing Unit) and a ROM (Read Only Memory). It is realized by RAM (Random Access Memory), IC (Integrated Circuit), LSI (Large Scale Integration) and the like.

  In addition, each node that joins the digital wireless communication system has the same configuration.

  Thereby, in the message transmission method of the present invention, the transmission source node acquires the position information of the transmission source node, and multicasts the acquired position information of the transmission source node. When the source node receives the position information of the other node that has received the position information multicasted from the source node among the plurality of nodes, the source node compares the length of the message to be transmitted with a predetermined length and compares the length of the message. If the length is longer than the predetermined length, the distance between the position information of the other node and the position information of the transmission source node is calculated. When the distance is longer than the distance threshold, the transmission source node stops transmitting the message to other nodes.

  Further, the message transmission method of the present invention calculates the length of the message to be transmitted, the distance between the position information of the transmission source node and the position information of the other node, and the transmission waiting time of the message as parameters. A threshold is set, and message transmission is stopped according to a comparison result between the calculated parameter and the threshold.

  With the above-described configuration, the operation of the control circuit 15 according to the present embodiment will be described in detail.

(A) Transmission of position information The control circuit 15 of each node periodically acquires its own position from the GPS receiver 2 via the GPS receiver interface unit 10, and holds the latitude and longitude of its own node as its own position information. Write to part 11. The control circuit 15 sets the magic number, latitude and longitude as the position information of each node in the user data area 43 of the UDP packet, and the IP address and position of the own node in the “from” field and the “to” field, respectively. Sets a multicast address for information exchange. The control circuit 15 outputs the UDP packet image having the position information, the IP address, and the multicast address to the wireless transmission / reception unit 4 via the wireless interface unit 9.

(B) Message Transmission Processing FIG. 4 is a flowchart showing message transmission processing according to the embodiment of the present invention. When a message transmission is requested from the terminal interface unit 8 (step A1), the control circuit 15 compares the message length with a preset limit length in step A2, and determines that the message length is shorter than the limit length. In this case, the message transmission process of step A6 is performed through the No route labeled N. In step A 6, the control circuit 15 outputs the message body to the encoder 13, and the encoder 13 breaks down the predetermined number of UDP / IP packets and wirelessly transmits / receives the broken UDP / IP packets via the radio interface unit 9. Output to part 4.

  On the other hand, if the control circuit 15 determines that the message length is greater than or equal to the limit length in step A2, the control circuit 15 passes the Yes route marked with Y, and in step A3, the control circuit 15 enters the destination node entry in the location information database 12. The location information database 12 is searched using the IP address 18 of the destination node as a search key.

  In this step A3, if there is an entry for the destination node, the Yes route is passed. In step A4, the control circuit 15 acquires the latitude and longitude of the destination node, and the acquired latitude and longitude and self-location information. The distance from the own node to the destination node is calculated using both the latitude and longitude of the own node held in the holding unit 11.

  If the control circuit 15 cannot find an entry corresponding to the location information database 12 in step A3, the route passes through the No route. In step A7, the control circuit 15 determines that communication is impossible, and sets the destination node. Set the distance to infinity.

  In step A5, the control circuit 15 compares the distance calculated in step A4 with a preset limit distance. If the calculated distance is larger than the limit distance, the control circuit 15 passes through the No route, and further in step A8, the terminal The failure is notified to the interface unit 8, and the message transmission is stopped to the transmission destination node in the communication disabled state. Accordingly, message transmission is canceled for a destination node having low packet reachability. In this case, the control circuit 15 writes the unsent message in the unsent message holding unit 24 (step A9).

  On the other hand, if the calculated distance is equal to or less than the limit distance in step A5, the Yes route is passed, and in step A6, the control circuit 15 outputs the message body 20 to the encoder 13 and decomposes it into a UDP / IP packet. 13 outputs to the wireless transmission / reception unit 4 via the wireless device interface unit 9.

(C) Reception processing The control circuit 15 inspects the magic number 16 (FIG. 3B) of the image of the UDP / IP packet input from the radio interface unit 9, and if the packet includes position information. For example, the IP address, latitude, longitude, and reception time of the transmission source node are registered as entries in the position information database 12.

  On the other hand, if the magic number 16 is not included in the received packet, the control circuit 15 determines that the packet is a disassembled message, assembles the message using the decoder 14, and transmits the assembled message to the terminal interface. Output to unit 8.

(D) Updating process of the position information database 12 The control circuit 15 deletes the entry having the reception time determined to be very old from the current time from the position information database 12 for each preset time. The control circuit 15 can appropriately determine this time determination criterion.

  In this way, according to the present invention, each node periodically multicasts its own location information and exchanges location information between transmitting and receiving nodes, and each node receives the received location information and the address of the originating node as location information. By holding in the database 12, when the transmission node is requested to send a message of a predetermined length or longer, if the distance between the destination node and the own node is a predetermined value or more, By wasting the message, the sending node can avoid wasting bandwidth.

  Therefore, according to the wireless communication apparatus according to the present embodiment, message filtering can be performed by using the location information of the transmission source node and the location information of the transmission destination node. Furthermore, the wireless communication apparatus according to the present embodiment has a long message that may compete with other communication processing in an environment where the quality of the communication path is poor and the reachability is low. You can cancel sending a message.

  In this way, according to the present invention, each node is unlikely to reach a destination node, and the long node addressed to a remote destination node that may interfere with other communication processing in the message transmission process. Message transmission can be canceled, message transmission can be performed effectively, and packet transfer efficiency can be improved.

  Further, according to the present invention, the band can be efficiently used with a relatively simple configuration.

  In addition, the digital radio | wireless communications system currently disclosed by said embodiment can be implemented in various deformation | transformation in the aspect which does not change the meaning of this invention. The message transmission method described above uses the IP address of the destination node included in the UDP / IP packet as transfer control information as an example of connectionless communication, but the present invention differs from the IP address of the destination node. Data can also be used as transfer control information.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, the present invention can be applied to a digital wireless communication system of any wireless specification, and the superiority of the present invention is not impaired at all for an embodiment in which the wireless specification is merely changed.

It is a figure which shows the structural example of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is a block diagram which shows an example of the communication control part used for a radio | wireless communication apparatus. (A) is a figure which shows an example of the data format of a UDP / IP packet, (b) is a figure which shows an example of the transmission message format which concerns on this embodiment. It is a flowchart which shows the message transmission process which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Terminal, 2 ... GPS receiving part (own node information acquisition part), 3 ... Communication control part, 4 ... Wireless transmission / reception part, 5, 6 ... LAN, 7 ... Serial cable, 8 ... Terminal interface part, 9 ... Radio | wireless machine Interface unit, 10 ... GPS receiver interface unit, 11 ... self-location information holding unit, 12 ... position information database (holding unit), 13 ... encoder, 14 ... decoder, 15 ... control circuit (other node information writing unit, message transmission) Stop unit, message length determination unit), 16 ... magic number, 17 ... payload, 18 ... IP address, 19 ... message length, 20 ... message body, 21 ... other node information writing unit, 22 ... message length comparison unit, 23 ... Message transmission stop unit, 24 ... Unsent message holding unit, 40 ... Node, 41 ... UDP / IP packet, 2 ... header area, 43 ... user data area.

Claims (10)

A wireless transceiver for transmitting and receiving wireless data;
An other node information writing unit capable of writing position information of another node received by the wireless transmission / reception unit in a holding unit holding data;
A local node information acquisition unit that acquires positional information of the local node;
Calculate the distance between the location information of the destination node held in the holding unit and the location information of the own node acquired by the own node information acquisition unit, and based on the distance and the distance threshold, A wireless communication apparatus comprising: a message transmission stop unit that stops transmission. A message length comparison unit that compares a message length addressed to the destination node with a message length threshold;
The wireless communication apparatus according to claim 1, wherein the message transmission stop unit calculates the distance when the message length comparison unit determines that the message length is greater than the message length threshold.   The wireless communication apparatus according to claim 1, wherein the holding unit holds data in which a destination address of the other node is associated with a latitude and longitude of the other node as the position information.   The wireless communication apparatus according to claim 3, wherein the holding unit further holds time information associated with the position information.   The wireless communication apparatus according to claim 1, wherein the message transmission stop unit calculates the distance as an infinite length when position information of the transmission destination node is not held in the holding unit.   The writing in the other node information writing unit updates the location information of the destination node after recovery when communication with the destination node to which the message transmission stop unit has stopped transmission is recovered. The wireless communication apparatus according to claim 1.   The wireless communication apparatus according to claim 1, wherein the wireless transmission / reception unit periodically multicasts the position information of the own node.   The transmission in the wireless transmission / reception unit is performed by transmitting the unsent message from an unsent message holding unit that holds an unsent message when communication with the destination node to which the message transmission stop unit has stopped transmission is recovered. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus transmits to a destination node. A message transmission method in a transmission source node that transmits and receives wireless data to and from a plurality of nodes,
The source node obtaining location information of the source node;
The source node multicasting the acquired location information of the source node; and
The source node receiving the location information of another node that has received the location information multicast from the source node of the plurality of nodes;
The source node compares the length of the message to be transmitted with a predetermined length;
The source node, when the length of the message is longer than a predetermined length, calculating the distance between the location information of the other node and the location information of the source node;
And a step of stopping the transmission of the message to the other node when the source node is longer than a distance threshold.   The length of the message to be transmitted, the distance between the location information of the transmission source node and the location information of the other node and the transmission waiting time of the message are calculated as parameters, the threshold for each parameter is set, the calculated parameter and the A message transmission method, wherein transmission of the message is stopped according to a comparison result with a threshold value.

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