Tradeoff Between Throughput and Energy Consumption in Multirate Wireless Sensor Networks

In wireless networks, multirate capability will facilitate using channel resource and reducing the bit error rate effectively. Current contention-based MAC protocols, however, behave inefficiently in multirate situations, leading to the performance anomaly problem. This paper researches the throughput deterioration in multirate wireless sensor networks. Initially, this paper refers to the notion of fairness to solve the performance deterioration problem and demonstrates that the utility maximization of throughput will be achieved when each contending node receives an equal proportion of channel occupancy time. Besides, considering the intrinsic tradeoff between throughput optimization and energy consumption optimization, the paper converts the tradeoff to the regulation of single node's channel access probability, which is determined by node's data rate and energy level. Finally, based on the contention-based MAC algorithm, the paper proposes an improved MAC protocol. Simulation validates that different application demands between throughput and lifetime can be adjusted flexibly and efficiently by regulating the tradeoff factor in the algorithm.

I. Introduction

With the expansion of wireless sensor network (WSN) and the ongoing development towards future Internet of Things (IoT), “information service” rather than “connection service” will become the basic feature of ubiquitous information society. Wireless sensor network acts as the information acquisition engine and perception extension of Internet of Things. Its core value is the ability to collect massive information in a multi-angle and multi-parameter way. Therefore the massive information collected requires the network to have stronger data transmission capacity. All data frames are sent with a single rate at first as defined in wireless network protocols such as IEEE 802.11. With the development of physical layer, multirate ability can be supported by different modulation schemes and channel coding methods. Nowadays, common wireless network international standards such as IEEE 802.11b and IEEE 802.15.4 provide support for multi-rate capability.