| 摘要 |
Wireless devices in ( 10, 20, 30 etc) in an ad hoc network each select a channel on which to operate such that conflicts with neighbouring devices are avoided. Each device ( 20 ) has a normal power output, giving it a normal range ( 31 ) and an enhanced power output, giving it an extended "inhibition" range ( 33 ). Initially each device ( 20 ) transmits at the enhanced power level, such that it can be detected by devices ( 40, 50 ) within the extended range ( 33 ). If it detects other devices transmitting on the same channel, it may change to another channel. Once a channel has been identified on which no conflict is detected, the device ( 20 ) switches to the normal power level. By initiating the channel selection process at the enhanced level, conflicts between the transmissions of devices ( 20, 40 ), which would be detectable at a device ( 30 ) within the normal range of both, can be avoided despite the two devices ( 20, 40 ) not be able to detect each other directly at the normal power level. To conserve battery power, the process is arranged to have the devices operate at the enhanced power for the minimum time necessary, by dropping to the normal level when a suitable channel has been identified with a reasonable degree of certainty.
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