IEEE SENSORS JOURNAL, vol.16, no.12, pp.5084-5094, 2016 (SCI-Expanded)
In pursuit of better energy efficiency and enhanced network lifetime in wireless sensor networks (WSNs), two crucial factors are data packet size and transmission power level. On one hand, smaller packet size reduces the overall impact of bit error rates on packet loss. However, the consequence of smaller packet size is fragmentation into more data packets and thereby dissipation of increased energy. Hence, there emerges a delicate engineering tradeoff in deciding the data packet size, where both low and high data packet size decisions lead to certain energy inefficiency issues. On the other hand, increasing transmission power level decreases packet loss probability, which is another decision variable to optimize for maximizing network lifetime. Joint consideration of these two factors exacerbates the complexity of the optimization problem for the objective of the network lifetime maximization. In this paper, we develop a realistic WSN link layer model built on top of the empirically verified energy dissipation characteristics of Mica2 motes and WSN channel models. We make use of the aforementioned link layer model to design a novel mixed integer programming (MIP) framework for the joint optimization of transmission power level and data packet size to take up the challenge introduced above. Numerical evaluations of the MIP framework with the analysis of the results over a large parameter space are performed to characterize the effects of joint optimization of packet size and power level on WSN lifetime.