Channel selection Clause Samples
Channel selection. When a device is enabled, it scans one or more channels for beacons and selects a channel. If no beacons are detected in the selected channel, the device creates its beacon period (BP) by sending a beacon. If one or more beacons are detected in the selected channel, the device synchronizes its BP to existing beacons in the selected channel. The device exchanges data with members of its beacon group using the same channel the device selected for beacons. Each device operates in a dynamic environment and under unlicensed operation rules. Thus, it is subject to interference from licensed users, other networks, and other unlicensed wireless entities in its channel. To enable the device to continue operation in this type of environment, each device has the capability to dynamically change the channel in which it operates without requiring disruption of links with its peers. If at any time a device determines that the current channel is unsuitable, it uses the dynamic channel selection procedure, as described in 8.11, to move to a new channel.
Channel selection. Selecting suitable RF channels requires a trade-off: The more channels are being used, the more options for avoiding fading effects and interference with other RF sources are available. Using too many channels, however, makes it more difficult for network nodes to join the network or to re- connect, since they have to search more channels to find the network. We found a channel hopping sequence using 3 channels to represent a good compromise. Channels 11, 19 and 26 of the 2.4 GHz band are recommended, which means the two ends of the available spectrum plus a channel in the middle are used. This way, maximum tolerance against fading can be achieved, other sources of interference can largely be avoided because they will in most cases affect only one of the three channels chosen and an energy-efficient yet reasonable fast network search is still possible.