A Distributed Ambient Backscatter MAC Protocol for Internet-of-Things Networks

Ambient backscatter communication enabling device-to-device (D2D) communications via the ambient radio frequency (RF) signal has revealed its numerous application potential in the Internet-of-Things (IoT) networks. However, the work on the link layer for the backscatter communication is in its infancy due to the constraints of ultralow power and cost in such a system, especially a channel access protocol in the backscatter communication system for IoT networks is rarely mentioned. In this article, a distributed multiple access control (MAC) protocol is presented, which allows multiple backscatter devices (BDs) to connect with each other by relying on the ambient RF signal. By combining an analog channel sensing strategy with the dual-backoff mechanism, each BD can switch among the transmission, receiving, and energy harvesting (EH) states. Specifically, each BD starts a randomly designated time for EH once the channel is sensed to be busy. As the timer expires, the BD ceases the EH and continues its sensing and backoff procedures. With the consideration of the false alarm and the miss detection problems occurring while sensing, an enhanced 3-D Markov model is built to analyze the saturation throughput performance of the proposed MAC protocol. Extensive simulations verify the analysis and demonstrate the advantage of the proposed backscatter MAC protocol.