John Heidemann

An Adaptive FEC Code Control Algorithm for Mobile Wireless Sensor Networks

TitleAn Adaptive FEC Code Control Algorithm for Mobile Wireless Sensor Networks
Publication TypeJournal Article
Year of Publication2005
AuthorsJ. - S. Ahn, S. - W. Hong, and J. Heidemann

For better performance over a noisy channel, mobile wireless networks transmit packets with FEC (Forward Error Correction) code to recover corrupt bits without retransmission. The static determination of the FEC code size, however, degrades their performance since the evaluation of the underlying channel state is hardly accurate and even widely varied. Our measurements over a wireless sensor network, for example, show that the average BER (Bit Error Rate) per second or per minute continuously changes from 0 up to 10-3. Under this environment, wireless networks waste their bandwidth since they can't deterministically select the appropriate size of FEC code matching to the fluctuating channel BER. This paper proposes an adaptive FEC technique called AFECCC (Adaptive FEC Code Control), which dynamically tunes the amount of FEC code per packet based on the arrival of acknowledgement packets without any specific information such as SNR (Signal to Noise Ratio) or BER from receivers. Our simulation experiments indicate that AFECCC performs better than any static FEC algorithm and some conventional dynamic hybrid FEC/ARQ algorithms when wireless channels are modeled with two-state Markov chain, chaotic map, and traces collected from real sensor networks. Finally, AFECCC implemented in sensor motes achieves better performance than any static FEC algorithm.