Optimal Cooperative MIMO Scheme in Wireless Sensor Networks
M. Riduan, Eryk Dutkiewicz, Xiaojing Huang, M. Kadim · InTech eBooks · 2010
This chapter presents a comparison study of three cooperative MIMO schemes in WSNs. We have developed analytical models for BER and PER to estimate retransmission rates from PER in (Ahmad et. al., 2008) and these are used to evaluate the total energy consumption and packet latency of the cooperative systems in this chapter. We show that the SISO scheme is more energy efficient and has lower latency at higher regions of transmission power while the three cooperative MIMO schemes are more energy efficient and outperform the SISO scheme at lower regions. Clearly, at the higher transmission power region, the SISO scheme enjoys lower transceiver circuit energy consumption and no energy cost at all on establishing a cooperative mechanism compared to the cooperative MIMO schemes. These results provide a constraint on the optimal transmission power or equivalently the optimal distance that should be used when implementing cooperative MIMO transmission in WSNs. From the analysis we can conclude that at the lower transmission power region, the cooperative optimal BF scheme outperforms both the cooperative SM and STBC schemes in terms of energy efficiency and packet latency for both perfect and imperfect synchronisation scenarios. Also we note that the cooperative BF scheme with M = 2 nodes is an efficient cooperative system. Further work will involve development of MAC protocols optimised for the cooperative transmission schemes and with the aim of creating an optimal cooperative transmission mechanism for use in distributed WSNs.