A Sustainable Design for MIoT-Based WBANs: A Cooperative CR Intra-WBAN With Integrated Backscatter and RF Energy Harvesting

Energy constraints and spectrum scarcity are two main challenges hindering the widespread adoption of wireless body area networks (WBANs) for the Medical Internet of Things (MIoT). This paper tackles these issues by proposing a novel cooperative cognitive radio (CR) intra-WBAN system that effectively integrates ambient backscatter communication (AmBC) and radio-frequency energy harvesting (RFEH). In the proposed design, body sensors (BSNs) are categorized into primary BSNs and cognitive BSNs based on their data latency requirements. A hybrid BSNs coexistence/cooperative energy and information transmit protocol is established, which enables cognitive BSNs to: 1) Opportunistically backscatter their data onto the primary source signal, thereby improving spectral efficiency, 2) Harvest RF energy from the primary signal for sustainable operation, and 3) Act as amplify-and-forward relays for the primary network in exchange for dedicated spectrum access. We derive analytical expressions for the outage probabilities of both primary and cognitive networks, and analyze the impact of key parameters, including the backscattering coefficient, spectrum-sharing power allocation factor, and time segmentation factor, on the outage probability of the network. Simulation results validate our analysis and demonstrate that the proposed scheme achieves a remarkable improvement in both network throughput and energy efficiency compared to existing work and other benchmark schemes, showcasing its significant potential for sustainable MIoT.