Wireless Body Area Networks (WBANs) are a fast-growing field fueled by the number of wearable devices developed for countless applications appearing on the market. To enable communication between a variety of those devices, the IEEE 802.15.6 standard was established. However, this standard has some intrinsic limitations in addressing the heterogeneity of the network nodes in terms of activity, data rates (from less than bit/s to multiple Mbit/s), energy availability, form factor, and location on, around or inside the body. To address these concerns, an alternative model is proposed that could serve as an extension of the IEEE 802.15.6 Standard. At its core is an adaptive and low-overhead synchronization scheme based on heartbeat sensing. This forms the base for a TDMA-based (Time Division Multiple Access) Media Access Control (MAC) protocol dedicated to multi-tier networks. While this effort focuses specifically on Capacitive Body-Coupled Communication (C-BCC), other physical layers can be easily incorporated as well. Based on these premises, this paper compares various random-access slot allocation approaches to accommodate the multiple data rates matching the system requirements, while incorporating a duty-cycling strategy anchored by heartbeat detection. This work proposes a novel, flexible, and robust solution, making use of heartbeat synchronization and addressing the corresponding challenges. It efficiently interconnects multiple device types over a wide range of data rates and targets a mesh of stars topology. At the cost of an increased communication latency, the proposed protocol outperforms the IEEE 802.15.4 MAC standard in terms of energy efficiency by a factor of at least 12x in a realistic scenario.

The Switched-Capacitor Power Amplifier (SCPA) has become a key enabler for modern wireless communication because of its high efficiency, high linearity, and high integrability. This paper discusses the impact of the extended Forward Body-Biasing (FBB) feature in 28 nm FD-SOI technology on Ultra-Low Voltage (ULV) SCPA. A new model of the Drain Efficiency (DE) and System Efficiency (SE) including body-biasing and drivers power consumption is introduced and validated with SpectreRF simulations. FBB on the SCPA improves by up to 14 % and 67 % the SE and transistors area, respectively, compared to a nominally body-biased SCPA under 0.5 V supply voltage at 2.4 GHz, while improving linearity and enhancing PVT variations.