Integrated energy analysis of error correcting codes and modulation for energy efficient wireless sensor nodes

Optimizing energy consumption is a key objective in designing wireless sensor nodes. It has been shown earlier that the node energy is strongly influenced by the modulation and the error correcting code (ECC) used. The utility of using ECC from an energy perspective is determined by the energy saving due to the ECC coding gain vis-a-vis the energy overhead of "redundant" bits and of energy saving. Furthermore, the node energy varies with the change in errorcorrecting capability and code word length of a particular ECC as well as the modulation constellation size. The ECC coding gain is influenced by the constellation size. In this paper, the node energy variations with ECC and modulation parameters are analyzed for an energy optimal node design for the nodes operating in the additive white Gaussian noise channel. Based on this analysis, we compute the per information bit node energy and this is used to select an "optimal" ECC and modulation scheme pair. Our results show that the energy optimal ECC-modulation pair selected for some specific operating conditions could save as much as 50% energy. In nutshell, our work is targeted towards reducing the search space and finding an energy optimal ECC modulation pair for the given environment and application.