This book addresses the design and analysis of Error Control Codes (ECC) and modulation techniques for energy efficient wireless sensor networks. It examines the advantages of choosing right ECC -Modulation pair to optimise the energy saving during the operation of a wireless sensor node. In this book, a system-level methodology is presented for exploring various ECCs with different modulation schemes while taking into account the transmit signal energy, the circuit energy, the encoder energy, as well as the decoder energy of a wireless sensor network node. Based on the energy tradeoffs between radio and computation functions, we find an energy-optimal ECC that reduces node energy consumption and hence increases the wireless sensor node battery life. In this book, a methodology for exploring various ECCs based on their energy consumption for sensor nodes have been proposed. For this exploration, an integrated framework that computes the radio energy, as well as the computation energy, has been built. Various configurations of Hamming codes, RS codes, and CCs have been explored.