Error Control Coding in Low-Power Wireless Sensor Networks: When Is ECC Energy-Efficient?

This paper examines error-control coding (ECC) use in wireless sensor networks (WSN), to determine the energy efficiency of specific ECC implementations in WSN. ECC provides coding gain, resulting in transmitter energy savings, at the cost of added decoder power consumption. This paper derives an expression for the critical distance dCR, the distance at which the decoder’s energy consumption per bit equals the transmit energy savings per bit due to coding gain, compared to uncoded. Results for several decoder implementations, both analog and digital, are presented for dCR in different environments over a wide frequency range. In free space, dCR is very large at lower frequencies, suitable only for widely spaced outdoor sensors. In crowded environments and office buildings, dCR drops significantly, to 3m or greater at 10 GHz. Interference is not considered; it would lower dCR. Analog decoders are shown to be the most energy-efficient decoders in this study.