Tolerable interference in multi-channel sensor networks: A measurement study

Interference plays an important role in the communication of wireless sensor networks. In this paper, we for the first time propose the concept of tolerable interference and investigate the tolerability of interference in multi-channel sensor networks with empirical measurements. We find that the transmission in sensor networks can tolerate certain level interference from the adjacent channels, which are not orthogonal to the current transmission channel. That is to say, the center frequency distance (CFD) for concurrent transmissions could be smaller than the default setting in sensor networks (i.e., 5 MHz in ZigBee). Concretely, with comprehensive experiments, we make two interesting observations: first, the throughput could be improved by relaxing CCA-threshold with the tolerable neighboring-channel interference; second, most of the corrupted packets caused by tolerable interference only have a small portion of error bits which could be corrected by introducing packet recovery scheme. Based on the above observations, we further have some discussions for better design of WSNs protocols, e.g., the system could enable some adaptive CCA-threshold scheme and packet recovery protocol to improve the overall throughput significantly.