JP2008193322A - Radio communication system, radio communication equipment, and route setting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve communication quality by stabilizing a communication route in an ad hoc network. <P>SOLUTION: A routing processing part 25 emits routing packets to its surrounding terminals with certain time intervals so as to search for a route. In response to this, neighboring terminals further transfer the routing packets to their surrounding terminals to search for the route. In so doing, intensity of the radio wave emitted by other radio terminals is measured by an intensity measurement part 26, notifies a routing processing part 25 of the result, and adjusts route update frequency so as to make a time interval of the route search long when the measured field intensity is strong and make the interval short when the intensity is weak. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio communication system forming an ad hoc network, a radio communication apparatus used in the system, and a route setting method.

As a routing protocol for forming an ad hoc network, AODV (Ad hoc On-Demand Distance Vector), OLSR (Optimized Link State Routing), and the like are known (for example, see Non-Patent Document 1). These protocols are used to optimize a communication path (route) between a plurality of moving wireless terminals.
However, it is known that, in the known protocol as described above, the route changes frequently in an environment where wireless terminals are concentrated in a relatively narrow area. Under such circumstances, the communication path is not stable, and therefore the communication quality becomes unstable.
Toshio Koide [online], [Search January 23, 2007], Internet <URL: http://internet.watch.impress.co.jp/www/column/wp2p/wp2p07.htm>

As described above, the existing technology has a problem in that a path is likely to become unstable when an ad hoc network is formed by a plurality of wireless terminals, resulting in a decrease in communication quality (QoS).
The present invention has been made in view of the above circumstances, and an object thereof is to provide a radio communication system, a radio communication apparatus, and a path setting method capable of stabilizing a communication path and thereby improving communication quality. It is in.

In order to achieve the above object, according to one aspect of the present invention, in a wireless communication system including a plurality of wireless communication devices forming an ad hoc network, each of the plurality of wireless communication devices is connected to another wireless device by a routing protocol. A routing processing unit (for example, the routing processing unit 25) that is formed while updating a communication path with a communication device to the ad hoc network, and a measuring unit (for example, an intensity measuring unit 26) that measures radio wave intensity related to wireless communication in the own device There is provided a wireless communication system comprising an update processing unit (for example, a connection destination calculation unit 25a) that changes the frequency of update of the communication path in accordance with the strength of the radio wave intensity.
In particular, the update processing unit updates the communication path at a first frequency if the radio wave intensity is equal to or higher than a specified level, and communicates at a second frequency higher than the first frequency if the radio wave intensity is lower than the predetermined level. Update the route.

  By taking such means, the communication path is updated at a relatively low frequency in a state where the radio field intensity is high. Conversely, in a state where the radio field intensity is low, the communication path is updated relatively frequently. As a result, the communication path is appropriately set according to the radio wave condition, and a good communication path can be ensured in any state.

  According to the present invention, the communication path can be stabilized, thereby improving the communication quality.

  FIG. 1 is a schematic diagram showing a wireless communication system forming an ad hoc network according to the present invention. This system includes a plurality of wireless terminals 11 to 17 to form an ad hoc network. Communication paths between the wireless terminals 11 to 17 are indicated by double arrows. This communication path is not fixed and is updated and set according to the passage of time and the movement of the individual wireless terminals 11 to 17.

FIG. 2 is a functional block diagram showing an embodiment of the wireless terminal of FIG. In FIG. 2, the radio signal arriving at the antenna 20 is channel-selected and demodulated by the tuning unit 21 and then amplified by the amplification unit 22. This amplified signal is given to the data extraction unit 23, and communication data such as voice is reproduced in response to a user operation via the interface unit 24. This communication data is given to the routing processing unit 25 and used for the routing processing.
Here, the radio signal demodulated in the tuning unit 21 is input to the intensity measuring unit 26, and the reception intensity is measured. That is, the intensity measuring unit 26 measures the radio wave intensity related to the wireless communication in the terminal itself. The result of this measurement is notified to the routing processing unit 25.

  The routing processing unit 25 includes a connection destination calculating unit 25a and a route calculating unit 25b as its control functions. The connection destination calculation unit 25a calculates connection destination terminals of the wireless terminals 11 to 17 according to specifications such as a band and a bit rate according to the system request. The route calculation unit 25b calculates the optimum communication route for the calculated connection partner using a routing protocol. This communication path is updated over time in the ad hoc network.

  By the way, the routing processing unit 25 changes the update frequency of the communication path roughly according to the strength of the reception strength notified from the strength measurement unit 26. That is, the routing processing unit 25 updates the communication path every 10 seconds, for example, when the radio wave intensity is equal to or higher than a predetermined threshold level. Further, if the radio wave intensity is lower than the threshold level, the routing processing unit 25 updates the communication path at a higher frequency, for example, every 1 to 5 seconds. That is, the routing period (frequency of route calculation) is variably controlled by the radio wave intensity.

  FIG. 3 is a flowchart showing a processing procedure in the wireless terminal of FIG. In FIG. 3, for example, the wireless terminal 11 waits for packet transfer from another terminal (step S1), and when a packet arrives, measures the radio field intensity (step S2). If the radio wave intensity is equal to or higher than the threshold level, the routing cycle is lengthened (step S3), and if it is weaker than the threshold level, the routing cycle is shortened (step S4).

  As described above, in this embodiment, the routing processing unit 25 radiates routing packets to surrounding terminals at certain time intervals in order to search for a route. In response to this, the neighboring terminal further forwards the routing packet to surrounding terminals to search for a route. At that time, the intensity measurement unit 26 measures the intensity of radio waves radiated from other wireless terminals, and notifies the result to the routing processing unit 25. If the measured radio field intensity is strong, the route search time interval is sparse, The route update frequency is adjusted so as to be denser if it is weak.

  In general, when terminals are densely packed, routes are easily switched. At this time, the strength of radio waves tends to increase. Since it is considered that the communication state is good when the radio field intensity is high, it is not necessary to frequently update the route, and inadvertently updating the route causes instability of the link. On the other hand, if the radio field intensity is weak, a preferable route is stably formed by frequently performing route calculation.

  The existing routing protocol has no viewpoint of monitoring the radio wave intensity, and the route is updated at a constant frequency in any radio wave condition. On the other hand, in the present embodiment, a more intelligent control is performed by adopting the viewpoint of monitoring the radio wave intensity when performing the routing. That is, in the ad hoc network protocol, the instability of the route is prevented by adding the radio wave intensity to the protocol parameter. From these facts, the communication path can be stabilized, thereby improving the communication quality.

  In addition, this invention is not limited to the said embodiment as it is. For example, the switching of the route update frequency is not limited to two steps, and may be performed more smoothly and in multiple steps depending on the strength of the radio wave intensity. In this way, finer control can be performed.

  Furthermore, the present invention can be embodied by modifying the constituent elements without departing from the spirit of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

The schematic diagram which shows the radio | wireless communications system which forms an ad hoc network concerning this invention. The functional block diagram which shows embodiment of the radio | wireless terminal of FIG. The flowchart which shows the process sequence in the radio | wireless terminal of FIG.

Explanation of symbols

  Wireless terminals 11 to 17, 20 ... antenna, 21 ... tuning unit, 22 ... amplification unit, 23 ... data extraction unit, 24 ... interface unit, 25 ... routing processing unit, 25a ... connection destination calculation unit, 25b ... route calculation unit, 26 ... Strength measuring section

Claims (6)

In a wireless communication system comprising a plurality of wireless communication devices forming an ad hoc network,
Each of the plurality of wireless communication devices is
A routing processing unit that forms a communication path with another wireless communication device by updating the ad hoc network using a routing protocol;
A measurement unit for measuring the radio field intensity related to the wireless communication in its own device;
A wireless communication system, comprising: an update processing unit that changes the frequency of updating the communication path roughly according to the strength of the radio wave intensity. The update processing unit updates the communication path at a first frequency if the radio field intensity is equal to or higher than a predetermined level, and updates the communication path from the first frequency if the radio field intensity is lower than the predetermined level. The wireless communication system according to claim 1, wherein the wireless communication system is updated at a high second frequency. In a wireless communication device forming an ad hoc network,
A routing processing unit that forms a communication path with another wireless communication device by updating the ad hoc network using a routing protocol;
A measurement unit for measuring the radio field intensity related to the wireless communication in its own device;
A wireless communication apparatus comprising: an update processing unit that changes the frequency of update of the communication path in accordance with the strength of the radio wave intensity. The update processing unit updates the communication path at a first frequency if the radio field intensity is equal to or higher than a predetermined level, and updates the communication path from the first frequency if the radio field intensity is lower than the predetermined level. The wireless communication device according to claim 3, wherein the wireless communication device is updated at a high second frequency. In a route setting method used in a wireless communication device that forms an ad hoc network with a communication route that is formed while being updated by a routing protocol,
Measure the radio field intensity related to wireless communication in its own device,
A route setting method, wherein the frequency of updating the communication route is changed roughly according to the strength of the radio wave intensity. If the radio field intensity is equal to or higher than a specified level, the communication path is updated at a first frequency. If the radio field intensity is lower than the predetermined level, the communication path is updated at a second frequency higher than the first frequency. The route setting method according to claim 5, wherein the route setting method is updated.

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