An Interference-Aware Adaptive Frequency Channel Selection Transceiver for Low Power Human Body Communication

Conventional wireless approaches for wearable body sensor networks suffer from body shadowing effects and high power consumption. Human body communication (HBC) utilizing the body's conductive properties offers a promising alternative but faces challenges from dynamic channel characteristics and environmental interference coupling in the sub-10 MHz electro-quasi-static (EQS) regime. To mitigate interference effects, existing transceivers employ narrowband operation with conservative carrier-to-data-rate ratios. This paper presents an interference-aware adaptive frequency hopping (AFH) human body communication (HBC) transceiver operating below 10 MHz, where AFH is realized as interference-driven adaptive channel selection. The proposed AFH on-off keying (OOK) transceiver integrates a tiny on-chip microcontroller unit (MCU) enabling autonomous frequency hopping control, real-time channel assessment, and direct sensor interfacing. Fabricated in 65-nm CMOS occupying 0.117 mm², the transceiver achieves 22-360 kbps data rates, -33 dB signal-to-interference ratio (SIR) tolerance at bit error rate (BER) of 10 ${}^{-3}$ , and 40 $\times$ BER improvement over single-frequency operation at maximum body distance of 180 cm. The transceiver achieves 62.2-79.5 pJ/bit energy efficiency, enabling extended battery life for distributed wearable applications, while benefiting from the inherent security of the sub-10 MHz EQS regime.