Ultrasonic Index Modulation and Multiple Access for Intra-Body Networks

Abstract

Intra-body communication (IBC) plays an significant role in future health care. This paper proposes a pulse-based ultrasonic index modulation (UsIM) to enable high data rate and low power IBCs. Two grouping-based UsIM strategies with a maximum likelihood receiver, including ultrasonic grouped-chip index modulation (UsCIM) and ultrasonic chip-group index modulation (UsGIM), are proposed to implement multiple access for intra-body networks. UsCIM uses the chip indices in a group to convey additional information bits for a user, while UsGIM uses the group indices and each user occupies one chip in a group. The performance of the proposed system in terms of bit-error rate (BER), throughput, and energy efficiency are analyzed. Both the analysis and simulation results reveal that UsGIM achieves a lower BER than UsCIM with channel fading and multipath effect. Both UsCIM and UsGIM achieve higher throughput and lower energy consumption than the existing IBC system, which is important for energy-constrained implanted systems.