Multi-channel support for preamble sampling MAC protocols in sensor networks

Many Medium Access Protocols (MAC) for sensor networks send a long preamble in front of data, and thus may suffer from long periods of busy channel. In this work, we address this problem and enable communication on multiple channels. Therefore, motes can send preamble immediately on another channel instead waiting for neighbors to finish transmissions. We carried out several experiments to find best settings for 868 MHz frequency. For instance, we discovered the channel spacing of 200 kHz is large enough, and it allows 35 channels in the limited European frequency bands. Adding several channels to preamble-sampling MAC increases energy consumption, as motes must scan multiple channels and not only the single one. However, by tweaking CC1101 transceiver, we shortened the scan time of a single channel to 0.38 ms. In this way, our solution scans several channels faster than other protocols need for a single channel.