Protocol Sequences With Carrier Sensing for Wireless Sensor Networks
Yijin Zhang, Ming Zhang, Yuan–Hsun Lo, Wing Shing Wong · IEEE Internet of Things Journal · 2018
Protocol sequences are deterministic binary sequences of a common period, which enjoy some special Hamming cross-correlation property by design. In contrast to random or contention-based medium access control schemes, a protocol sequence-based scheme can serve to provide at least a certain number of contention-free packet transmissions within a bounded delay for each asynchronous user in a feedback-free multiple access system. However, all protocol sequence-based schemes in the literature require that all sequence entries are mapped to slots with the same time duration, which produces a relatively low channel utilization. To overcome this inefficiency that is undesirable in delay-constrained wireless sensor networks, building on the idea of combining sequence-based access and carrier sensing, this paper proposes a new protocol sequence-based scheme, called the PS-CS. We derive the theoretical average throughput, average access delay, worst-case delay, and average energy consumption of the PS-CS. It is shown that the PS-CS produces average throughput close to the optimal capacity of p-persistent carrier sense multiple access (CSMA), and enjoys smaller access delay than the optimal p-persistent CSMA. In addition, we study the energy-delay tradeoff, impact of carrier sensing fault and channel error, and how to modify the PS-CS to support real-time downlink for feedback control.