Medium access control in wireless sensor networks: a survey

Abstract

Wireless sensor networks (WSNs) are being integrated across a wide spectrum of military, commercial, and environmental applications, such as field surveillance, environmental monitoring, and disaster management. This variety in WSN applications led to the development of a large number of medium access control (MAC) protocols with different objectives. A common goal of these protocols however, is preserving energy in order to maximise network lifetime. In an effort to facilitate studying existing MAC protocols and developing novel medium access techniques, this paper presents a classification and critical review of existing MAC protocols adopted in different WSN environments. We classify these protocols based on channel access into three main categories: contention-based, contention-free, and hybrid protocols. Cross-layer protocols (involving MAC layer) are also studied. We describe major characteristics of these classes, differences among them, possible improvements, and outline ongoing and future research challenges.