JP2005347850A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of selecting a path in an adhoc network by taking into consideration a traffic amount between a sender terminal and a destination terminal. <P>SOLUTION: In the radio communication system wherein packets are transmitted / received between the sender terminal and the destination terminal via at least one relay terminal in the adhoc network including a plurality of terminals, the sender terminal broadcasts a path request packet to the destination terminal, the relay terminal appends its own available band and its own address to the path request packet and broadcasts the resulting path request packet, the destination terminal selects a path for transmitting / receiving the packets to / from the sender terminal on the basis of the available band appended to the path request packet and informs the sender terminal about the selected path, and the sender terminal sets the path notified from the destination terminal as a path through which the packets are transmitted / received to / from the destination terminal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for transmitting and receiving a packet between a source terminal and a destination terminal via at least one relay terminal in an ad hoc network including a plurality of terminals.

  In connection control of ATM (Asynchronous Transfer Mode) in a wired network, when setting a communication connection between a specific source terminal and destination terminal, that connection is required at the end and end of the route. There is a method for notifying the network switch of the bandwidth, checking the available bandwidth at each terminal and each link on the route, and comparing the bandwidth requested by the terminal to determine whether connection setting is possible. Has been established.

  Also, in the wired network, when there are multiple paths between two terminals, as a method of selecting the path with the minimum delay, the queue length of each relay node of each path and the bandwidth usage of each link are set. There is a known method for selecting the minimum delay path by estimating and comparing the end / end delay of each path.

  On the other hand, in an ad hoc network, as a technique for achieving the same purpose as described above, a specific transmission source terminal / destination terminal to which a communication connection is to be set inquires of each terminal of the network about the traffic amount of the wireless LAN of the terminal. A method is proposed that uses information to estimate the available end-to-end bandwidth and end-to-end delay for multiple routes that can be used between two terminals, and to select a route that satisfies the quality required by the communication connection. Has been. Note that in an ad hoc network, a large number of terminals transmit and receive packets to and from each other without intervention of an access point while using a technology such as IEEE 802.11x that is widely used for wireless connection of computers and the like.

  The above-described conventional method is generally considered applicable to an ad hoc network in which a terminal does not move at high speed. However, in an environment where the terminal moves at high speed, in order to estimate the usable bandwidth at the end and end of the route, a method that can accurately estimate while dealing with the route fluctuation between the terminals accompanying the movement of the terminal must be used. Don't be. However, in the conventional method described above, a general and specific estimation method that can cope with a change in the route is not shown, and it is difficult to realize the estimation method.

In addition, there exist the following as what is considered to be related to this invention (refer patent document 1, 2, 3).
JP 2003-152786 A JP 2004-48478 A JP 2004-56787 A

  A first problem of the present invention is to make it possible to select a route in consideration of the amount of traffic between a transmission source terminal and a destination terminal in an ad hoc network. The second problem of the present invention is observed in each ad hoc network when each terminal classifies its own wireless LAN traffic volume according to the flow level of the network layer, and further, when the path changes in each flow. A determination is made as to whether or not the traffic information is invalidated, and this is used to estimate the available bandwidth of the route between a specific source terminal and destination terminal.

  The present invention has been made to solve the above-described problem, and wireless communication in which packets are transmitted and received between a transmission source terminal and a destination terminal via at least one relay terminal in an ad hoc network including a plurality of terminals. In the system, when the transmission source terminal broadcasts a route request packet toward the destination terminal and the relay terminal receives the route request packet, the source terminal indicates its own available bandwidth and its address. Add to the request packet, broadcast the route request packet after the addition, and when the destination terminal receives the route request packet, the source terminal and the source terminal based on the available bandwidth added to the route request packet A route for transmitting and receiving the packet is selected, the selected route is notified to the transmission source terminal, and the transmission and reception are further performed. Source terminal sets the notified path from the destination terminal as a route for transmitting and receiving packets to and from the destination terminal.

  According to the present invention, in an ad hoc network, it is possible to select an optimal route in consideration of the amount of traffic between a transmission source terminal and a destination terminal (for example, indicated by the available bandwidth of the present embodiment).

  In the wireless communication system, for example, each terminal measures the address of the source terminal, the address of the destination terminal, and the traffic volume of the packet transmitted / received via the set route, and the observed packet By measuring the amount of traffic for each flow grouped together for the same set of source address and destination address, creating a traffic list for each flow, and referring to this traffic list for each flow, calculate.

This exemplifies a method for calculating the available bandwidth. Therefore, in the present invention, the available bandwidth can be calculated not only by this method but also by various other methods.
In the wireless communication system, for example, when a route is set again between the specific source terminal and the destination terminal after the route between the specific source terminal and the destination terminal is disconnected, the flow Of these, the available bandwidth is calculated without considering this for the traffic of the flow of the set of the address of the specific source terminal and the address of the destination terminal.

  In this way, in an ad hoc network, each terminal classifies its own wireless LAN traffic volume according to the flow level of the network layer, and further, when the path changes in each flow, the observed traffic information is It is possible to estimate whether or not to invalidate and use this to estimate the usable bandwidth of a route between a specific source terminal and destination terminal.

The present invention can be specified as a method invention as follows.
A wireless communication method for transmitting and receiving a packet between a source terminal and a destination terminal via at least one relay terminal in an ad hoc network including a plurality of terminals, wherein the source terminal is directed to the destination terminal When the relay terminal receives the route request packet, it appends its available bandwidth and its address to the route request packet, and broadcasts the route request packet after the addition. When the destination terminal receives the route request packet, the destination terminal selects a route for transmitting / receiving the packet to / from the transmission source terminal based on the available bandwidth added to the route request packet, and this selection The destination terminal is notified to the source terminal, and the source terminal further notifies the destination terminal of the route notified from the destination terminal. It sets as a path for transmitting and receiving packets between the wireless communication method.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible in an ad hoc network to select the path | route which considered the traffic amount between a transmission origin terminal and a destination terminal. Further, even in a situation where the terminal moves in the ad hoc network, it is possible to appropriately select a route that satisfies the quality required by the transmission source terminal and the destination terminal.

A wireless communication system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining an outline of a wireless communication system according to an embodiment of the present invention.
Each vehicle (X, A, B, Y, A ′, B ′, C ′, I) shown in FIG. 1 is equipped with a terminal 10 (see FIG. 2) that includes wireless LAN transceivers 20, 30. An ad hoc network is formed.

  The terminal 10 is a mobile terminal (hereinafter simply referred to as a terminal) such as an in-vehicle computer or a so-called car navigation system, and a control device such as a CPU that controls the overall operation of the terminal 10 and a memory (both shown in FIG. And two wireless LAN transceivers 20 and 30 and the like. Each of the wireless LAN transceivers 20 and 30 may be detachably attached to the terminal in the form of a card, may be built in the terminal 10, or may be connected to the terminal 10 in another form. Good. Hereinafter, a terminal mounted on a vehicle may be displayed with a reference numeral of the vehicle (for example, a terminal mounted on the vehicle X is displayed as a terminal X).

  The wireless LAN transceiver 20 has a plurality of wireless LAN channels that can be used, and each terminal 10 constantly monitors the utilization rate of each channel and selects one of the most open channels to transmit a packet. Is used to send and receive data packets. In the single channel configuration, the throughput of the ad hoc network does not increase beyond the throughput of one channel of the wireless LAN, but in the multi-channel configuration, if the number of available wireless LAN channels is increased, the throughput can be increased accordingly. However, even in a multi-channel configuration, the amount of packets that can be transmitted and received by one terminal 10 is limited by the throughput of the wireless LAN transceiver 20. Here, the value is 6 Mbps. Therefore, in order to increase throughput in a multi-channel configuration, it is important to select a route so that the amount of data packets transmitted and received by each terminal 10 does not exceed 6 Mbps. The method will be described below.

The wireless LAN transceiver 30 is used to send and receive control packets.
In the ad hoc network configured as described above, a route is set between terminals, and data packets are transmitted and received between the terminals via this route.

  For example, FIG. 1 shows two routes in an ad hoc network: a route between terminals XY (terminal X → terminal A → terminal B → terminal Y) and a route between terminals A′C ′ (terminal A ′ → This indicates that the route from terminal B ′ to terminal C ′ is set. In this case, the data packet is transmitted between the terminals XY via the route of terminal X → terminal A → terminal B → terminal Y and between the terminals A′C ′ via the route of terminal A ′ → terminal B ′ → terminal C ′. Is sent and received.

An operation for setting these routes will be described.
Note that the operations described below are performed in the network layer of the OSI reference model. Therefore, unless otherwise specified, the address of each terminal 10 indicates a network address, and the format of the control packet indicates a packet format at the network layer.
(Route setting between source terminal and destination terminal)
(1) RREQ packet generation / broadcast at the source terminal The terminal X (source terminal) generates an RREQ (Route REQuest) packet destined for the terminal Y (destination terminal) and broadcasts it to the ad hoc network. This broadcast is performed by the wireless LAN transceiver 30 for transmitting and receiving control packets.

FIG. 3A shows a general format of the RREQ packet.
The RREQ packet is composed of a header part (broadcast address and source terminal address) and a payload part (destination terminal address and requested bandwidth) as in a normal packet.

  An identifier for identifying that the RREQ packet is a broadcasted packet is set in the broadcast address. The address of the source terminal (here, terminal X) is set as the address of the source terminal. The address of the destination terminal (here, terminal Y) is set as the address of the destination terminal. The requested bandwidth is set to the bandwidth required by the new connection. As a unit of the requested bandwidth, there can be a normalized value in addition to bit / sec. Here, a value normalized by the throughput of the wireless LAN is used as the value of the requested bandwidth. That is, in the example of FIG. 1, the value of the required bandwidth is 3 Mbps / 6 Mbps = 0.5.

The broadcast RREQ packet is received by a relay terminal (terminal A, B, etc.) between the terminal X (source terminal) and the terminal Y (destination terminal), and the following (2) (3) To finally arrive at the terminal Y.
(2) Calculation of RREQ packet reception and available bandwidth at each relay terminal Each relay terminal (terminal A, B, etc.) receives the RREQ packet according to its position. This is performed by the wireless LAN transceiver 30 for transmitting and receiving control packets. Then, each relay terminal (terminal A, B, etc.) refers to a flow-specific traffic list (described later) held by the own terminal, and transmits / receives a packet of a flow of (terminal X, terminal Y) in the transceiver 20 of the own terminal. Calculate the available bandwidth available for.

The available bandwidth is calculated as follows.
Available bandwidth = 1- (Sum of traffic amount of flows other than listed (terminal X, terminal Y) / wireless LAN throughput)
At this point, since the traffic list of the flow of each relay terminal (terminal A, B, etc.) is empty, the available bandwidth is 1.

In this way, each relay terminal (terminal A, B, etc.) calculates the available bandwidth.
(3) Addition / relay to RREQ packet in each relay terminal Each relay terminal (terminal A, B, etc.), after (2) above, sets its own terminal address and its calculated available bandwidth in the payload of the RREQ packet. After the additional recording, the RREQ packet after the additional recording is broadcast again to the ad hoc network. This broadcast is performed by the wireless LAN transceiver 30 for transmitting and receiving control packets.

FIG. 3B shows a general format of the RREQ packet when the terminal at the nth hop broadcasts from the source terminal.
(4) RREQ packet reception / route selection / notification at the destination terminal The terminal Y receives the RREQ packet transmitted in the above (1) to (3) via a plurality of routes. When the terminal Y receives the RREQ packet, the terminal Y refers to the requested bandwidth described in the RREQ packet and the available bandwidth described by each terminal (terminal A, B, etc.) on the route. Then, the terminal Y selects one route whose available bandwidth is greater than or equal to the requested bandwidth from the routes. This makes it possible to select a route that takes into account the amount of traffic between the transmission source terminal X and the destination terminal Y.

Here, it is assumed that the route of terminal X → terminal A → terminal B → terminal Y is selected. If there are a plurality of routes whose available bandwidth is equal to or greater than the requested bandwidth, it is conceivable to select the one with the largest available bandwidth or the one that has arrived at the terminal Y earliest. The terminal Y notifies the selected route to the terminal X via the ad hoc network.
(5) Route setting in transmission source terminal The terminal X sets the route (terminal X → terminal A → terminal B → terminal Y) notified from the terminal Y as the route to the terminal Y.

In addition, a route is set between both terminals A′C ′ by performing the same processing as the above (1) to (4).
(6) Data communication between source terminal and destination terminal Between terminal XY (same between terminals A'C '), data packets are transmitted along the set route (terminal X → terminal A → terminal B → terminal Y). Send and receive. This packet transmission / reception is performed by the wireless LAN transceiver 20 for transmitting / receiving the data packet.

  Specifically, data packets are transmitted and received between the terminals XY as follows. For example, when attention is focused on packet transmission from terminal X to terminal Y, first, terminal X has an address of a transmission source terminal (address of own terminal X), an address of a relay terminal (route notified from terminal Y) in a header portion or the like. The packet in which the addresses of the terminals A and B) and the address of the destination terminal (the address of the terminal Y) are written is transmitted to the terminal A by unicast.

  The terminal A receives this unicast packet, and the terminal A creates the following traffic list by flow and transmits it to the next terminal B written in the header portion by unicast. The terminal B receives this unicast packet. Similarly, the terminal B creates the following per-flow traffic list and transmits it to the next terminal Y written in the header portion by unicast. .

In this way, the packet transmitted from the terminal X finally arrives at the terminal Y via the route notified from the terminal Y (the relay terminals A and B constituting the terminal). Here, the description has been made focusing on packet transmission from the terminal X to the terminal Y, but the same processing is performed even if attention is paid to packet transmission from the terminal Y to the terminal X.
(7) Creating a traffic list for each relay terminal (periodic traffic observation and load index setting)
Each terminal 10 measures a source address, a destination address, and a traffic amount of a data packet transmitted and received by the wireless LAN transceiver 20 of the terminal within a certain time interval (for example, one second).

  Then, the observed packets are grouped every time the set (the combination of the source address and the destination address) is the same. This group is called a flow. Further, the traffic volume for each flow is measured for the observed packet, and a traffic list for each flow is created. As an example, FIG. 4 shows a list of terminal X, terminal Y, terminal A, terminal B, terminal A ′, terminal B ′, and terminal C ′ of FIG. 4A is a list held by the terminals X and Y, FIG. 4B is a list held by the terminals A and B, FIG. 4C is a list held by the terminal A′C ′, and FIG. ) Is a list held by the terminal B ′. For I in FIG. 1, since the transmission / reception is not performed in FIG. 1, the list is empty.

The traffic list by flow includes items of a flow number, a transmission source address, a destination address, and a traffic amount. The flow number is for identifying a flow. For example, as shown in FIG. 1, when a data packet is transmitted from the source terminal X to the destination terminal Y, the address of the terminal X is written in the source address, and the address of the terminal Y is written in the destination address. It is.
(8) Route Disconnection Under the conditions (6) and (7) above, assume that the terminal A moves and the route between the terminals XY is disconnected as shown in FIG. The process after this cutting will be described with reference to the flowchart of FIG.
(9) Generate / broadcast RREQ packet again at source terminal (S10)
When the terminal X (transmission source terminal) detects that the route between the terminals XY is disconnected, the RREQ (Route REQuest: route request) toward the terminal Y (destination terminal) is again performed in the same manner as (1) above. Generate a packet and broadcast it to an ad hoc network. This broadcast is performed by the wireless LAN transceiver 30 for transmitting and receiving control packets.

  As for the disconnection of the path between the terminals XY, for example, when the terminal B does not receive a packet from the terminal A for a certain period, the terminal B notifies the terminal X of the disconnection to detect the disconnection. Alternatively, the disconnection may be detected when the terminal X does not receive a packet from the terminal Y for a certain period.

The broadcast RREQ packet is received by a relay terminal (terminal B or the like) between terminal X (source terminal) and terminal Y (destination terminal), and performs the following (10) and (11) at the relay terminal. Finally, it arrives at the terminal Y.
(10) Re-RREQ packet reception / usable bandwidth calculation at each relay terminal (S11)
Each relay terminal (terminal B or the like) receives the RREQ packet according to its position. This is performed by the wireless LAN transceiver 30 for transmitting and receiving control packets. Each relay terminal (terminal B or the like) can refer to the flow-specific traffic list held by the terminal, and can be used by the transceiver 20 of the terminal to transmit / receive a packet of a flow of (terminal X, terminal Y). Calculate available bandwidth.

The available bandwidth is calculated as follows.
Available bandwidth = 1- (Sum of traffic amount of flows other than listed (terminal X, terminal Y) / wireless LAN throughput)
The rightmost column in FIG. 6 shows the calculation result at each terminal 10.

  Here, when calculating the available bandwidth, the reason why the flow traffic of (terminal X, terminal Y) in the list is not included is that the flow traffic of (terminal X, terminal Y) described in the list is ( This is because the value is related to the old route between the terminal X and the terminal Y), and the value is not valid when the terminal X performs a route search again.

Thus, each terminal 10 calculates the available bandwidth.
(11) Addition and relay to RREQ packet at each relay terminal (S12)
After the above (10), the relay terminal (terminal B or the like) adds the address of the terminal and the calculated available bandwidth to the payload of the RREQ packet, and broadcasts the added RREQ packet to the ad hoc network again. . This broadcast is performed by the wireless LAN transceiver 30 for transmitting and receiving control packets.
(12) Receipt / route selection of RREQ packet again at terminal Y (S13)
The terminal Y receives the RREQ packet transmitted by the above (9) to (11) via a plurality of routes. FIG. 7 shows that a total of four RREQ packets have been received via each of the four paths. When the terminal Y receives the RREQ packet, the terminal Y refers to the requested bandwidth described in the RREQ packet and the available bandwidth described by each terminal (terminal B or the like) on the route. Then, the terminal Y selects one route whose available bandwidth is greater than or equal to the requested bandwidth from the routes. Here, it is assumed that the route of terminal X → terminal I → terminal B → terminal Y is selected. When there are a plurality of routes whose available bandwidth is equal to or greater than the requested bandwidth, it is conceivable to select the one with the largest available bandwidth or the one that has arrived at the terminal Y earliest.
(13) Notification again at terminal Y (S14)
The terminal Y notifies the selected route to the terminal X via the ad hoc network.
(14) Route setting / communication start again (S15)
The terminal X sets the route notified from the terminal Y (terminal X → terminal I → terminal B → terminal Y) as the route to the terminal Y. Between the terminals XY, data packets are transmitted and received through the set route (terminal X → terminal I → terminal B → terminal Y). This packet transmission / reception is performed by the wireless LAN transceiver 20 for transmitting / receiving the data packet.

  Specifically, data packets are transmitted and received between the terminals XY as follows. For example, when attention is paid to packet transmission from terminal X to terminal Y, first, terminal X has the address of the transmission source terminal (address of own terminal X) and the address of relay terminal (route notified from terminal Y in the header part). The packet in which the addresses of the terminals I and B to be configured) and the address of the destination terminal (the address of the terminal Y) are written is transmitted to the terminal I by unicast.

  The terminal I receives this unicast packet, and the terminal I creates the above-mentioned traffic list for each flow and transmits it to the next terminal B written in the header portion by unicast. The terminal B receives this unicast packet. Similarly, the terminal B creates the above-mentioned traffic list by flow and transmits it to the next terminal Y written in the header portion by unicast.

  In this way, the packet transmitted from the terminal X finally arrives at the terminal Y via the route notified from the terminal Y (the relay terminals I and B constituting the terminal). Here, the description has been made focusing on packet transmission from the terminal X to the terminal Y, but the same processing is performed even if attention is paid to packet transmission from the terminal Y to the terminal X.

  As described above, according to the wireless communication system of this embodiment, even in a situation where the terminal A moves in the ad hoc network, a route that satisfies the quality required by the source terminal X and the destination terminal Y is appropriately selected. It becomes possible to do. Further, when a route is set between a certain source terminal (example of terminal X in FIG. 1) and destination terminal (example of terminal Y in FIG. 1), each relay terminal (terminal A and terminal B in FIG. Classify the wireless LAN traffic information observed by example) for each flow, extract the amount of traffic other than the flow set between the two terminals of interest, calculate the available bandwidth / delay for that flow, and Select the route between. As a result, even in an environment in which the terminal moves, it is possible to select a route that satisfies the bandwidth required by the flow and has a small delay.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. For this reason, said embodiment is only a mere illustration in all points. The present invention is not construed as being limited by these descriptions.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible in an ad hoc network to select the path | route which considered the traffic amount between a transmission origin terminal and a destination terminal. Further, even in a situation where the terminal moves in the ad hoc network, it is possible to appropriately select a route that satisfies the quality required by the transmission source terminal and the destination terminal.

It is a figure for demonstrating schematic structure of the radio | wireless communications system which is one Embodiment of this invention. It is a figure for demonstrating schematic structure of a terminal. It is a figure for demonstrating the format of a RREQ packet. It is an example of the traffic list classified by flow. It is a flowchart for demonstrating operation | movement of the radio | wireless communications system which is one Embodiment of this invention. It is an example of calculation of the available bandwidth for the flow in each terminal. It is an example of information on the route obtained at the destination terminal Y and the usable bandwidth of the route.

Explanation of symbols

10 Terminal 20 Wireless LAN transceiver 30 Wireless LAN transceiver

Claims (4)

A wireless communication system that transmits and receives packets between a source terminal and a destination terminal via at least one relay terminal in an ad hoc network including a plurality of terminals,
The source terminal broadcasts a route request packet toward the destination terminal;
When the relay terminal receives the route request packet, it adds its own available bandwidth and its address to the route request packet, broadcasts the route request packet after the addition,
When the destination terminal receives the route request packet, it selects a route for transmitting / receiving the packet to / from the transmission source terminal based on the available bandwidth added to the route request packet, and this selected Notify the source terminal of the route,
Furthermore, the wireless communication system in which the transmission source terminal sets a route notified from the destination terminal as a route for transmitting and receiving packets to and from the destination terminal.   Each terminal measures the address of the source terminal, the address of the destination terminal, and the traffic volume of the packet transmitted / received through the set route, and the observed packet is measured by the source address and the destination address. 2. The available bandwidth is calculated by measuring a traffic amount for each flow grouped for the same set and creating a traffic list for each flow, and referring to the traffic list for each flow. Wireless communication system.   When a route is set again between the specific source terminal and the destination terminal after the route between the specific source terminal and the destination terminal is disconnected, the specific source terminal of the flow The wireless communication system according to claim 2, wherein the available bandwidth is calculated without considering the traffic of the flow of the set of the address and the address of the destination terminal. A wireless communication method for transmitting and receiving packets between a source terminal and a destination terminal in an ad hoc network including a plurality of terminals via at least one relay terminal,
The source terminal broadcasts a route request packet toward the destination terminal;
When the relay terminal receives the route request packet, it adds its own available bandwidth and its address to the route request packet, broadcasts the route request packet after the addition,
When the destination terminal receives the route request packet, it selects a route for transmitting / receiving the packet to / from the transmission source terminal based on the available bandwidth added to the route request packet, and this selected Notify the source terminal of the route,
Furthermore, the wireless communication method in which the transmission source terminal sets a route notified from the destination terminal as a route for transmitting and receiving packets to and from the destination terminal.

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