A parallel joint optimized relay selection protocol for wake-up radio enabled WSNs

Abstract

Conflicts in the data transmission lead to a serious waste of energy, so it is pivotal to design a parallel and less conflict communication protocol for sensing nodes with limited energy. In this paper, a Parallel joint Optimized Relay Selection (PORS) protocol is proposed to reduce collision, delay as well as energy consumption for wake-up radio enabled WSNs. First, the basic Consecutive Packet Transmissions (CPT) method is adopted by PORS protocol. In this method, once a node obtains the channel, its data packets are sent continuously at once, and other nodes go to sleep in this period to reduce channel conflicts and save energy. Then, two thresholds namely maximum waiting queue length and waiting time are set for each node. When the data packets of the node do not meet the threshold, it keeps silent to reduce channel conflicts, and accumulates more packets to increase the number of data packets sent at once, thereby improving energy efficiency. Furthermore, a relay node selection approach is proposed by comprehensively considering factors such as the number of data packets, waiting time, and remaining energy. Those nodes that have many packets, long waiting time, and a large amount of remaining energy are more likely to be selected as relay nodes, so that they can receive more data packets in a short time and meet the threshold requirements as soon as possible. While the other nodes try not to obtain data and keep silent on the channel, thus reducing the collision as well as delay. Finally, the threshold values of nodes in adjacent layers differ by a constant. Thus, the crossing nodes of adjacent layers can transmit data in parallel to reduce the collision and delay Comprehensive analysis and experimental results demonstrate that the average energy consumption is reduced by 11.9%, network lifetime is increased by 26.1%, and network delay is reduced by 35.6% compared with the strategy with the fixed relaying nodes.