Energy optimization in multi-hop wireless sensor networks

Energy consumption in wireless sensor networks is a very important issue due to battery operated nodes. In this paper energy consumption in the physical layer by considering two modulation schemes in multi-hop communication is discussed. It was assumed that all nodes are spaced in a direct way and distance between them is equal. In this way, by introducing the energy model for two modulation schemes named Offset Quadrature Phase Shift Keying (OQPSK) and M-array Frequency Shift Keying (MFSK) which are the most applicable schemes in WSN based on IEEE 802.15.4, the optimum distance between nodes for both is determined based on error probability, channel bandwidth, path loss factor and etc. It was shown that in modulating signal by 2FSK in some distances energy consumption in single hop is less than multi-hop, while in OQPSK modulation multi-hop is always better than single hop.