Decentralized channel selection in a self-organizing ADHOC network and wireless communication relay equipment

Abstract

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 noconflict 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 identifiedwith a reasonable degree of certainty.

Description

technical field [0001] The present invention relates to channel selection in wireless communication networks, in particular to channel selection in ad hoc communication networks. Background technique [0002] An important factor in configuring any wireless network is to avoid co-channel interference between transmitters operating on the same frequency. Traditionally, the network architecture is planned in advance, and the necessary infrastructure is then configured according to that plan. However, this approach may not be practical in situations where the network needs to be configured quickly, or where there are too many unknown factors, such as harsh environmental conditions or unpredictable spatial distribution of network components. These factors are especially relevant in situations where there is insufficient time or information to plan resource allocation, such as disaster relief or war situations. Pre-planning is also not practical in situations where the equipment...

AI Technical Summary

Problems solved by technology

However, this introduces its own difficulties

One difficulty is that issuing an ACK consumes battery power, which can be a serious limitation in an ad-hoc environment where devices operate on battery power and are difficult to access

A second, more subtle but more complex difficulty to deal with is that ACKs themselves may collide or be lost, with the likely result being permanent instability

The question then becomes how to make two devices cooperate with each other to avoid interference when such interference can occur where multiple devices cannot detect each other directly

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