TSS: An Energy Efficient Communication Scheme for Low Power Wireless Networks

Wireless sensor networks typically require low cost devices and low power operations. Hence, such networks usually employ radios with only simple modulation techniques such as ASK, OOK and FSK. We propose a new energy efficient communication scheme for wireless sensor networks that is based on the ternary number system encoding of data. An efficient algorithm for conversion from binary to ternary and vice versa is used that does not involve any division or multiplication but only addition. Our Ternary with Silent Symbol (TSS) communication scheme is similar in concepts to the RBNSiZeComm protocol proposed. However, in contrast to RBNSiZeComm, TSS simultaneously saves energy at both the transmitter and receiver due to shortening of the transmission duration. We also propose a transceiver design that uses a hybrid modulation scheme utilizing FSK and ASK so to keep the cost/complexity of the radio devices low. With a non-coherent detection based receiver and assuming equal likelihood of all possible binary strings of a given length, there is a savings of about 20% in energy on an average at the transmitter compared to binary FSK, for additive white gaussian noise (AWGN) channels. Simultaneously, there is a savings of 36.9% at the receiver too, due to the reduced length of ternary encoded transmitted data, compared to binary encoding. Coupled with the low cost and low complexity of the transceiver, these results establish the effectiveness of TSS as a suitable candidate for communication in low power wireless sensor networks.