I. Introduction
Wireless sensor networks (WSNs) [1] consist of many sensor nodes that communicate with each other to perform a collective task such as sensing an environment. The main duty of these nodes is sensing and communicating the gathered information from the ambient environment to the Base Station (BS) or sink. Meanwhile, a sensor node is characterised by a limited computational and communication power. These constraints make the designing of an effective medium access control (MAC) protocol in WSNs a challenging task in aim to determine the channel access control capabilities and the energy consumption properties of WSNs. The MAC protocol of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) for carrier transmission in WSNs avoids collisions by transmitting only when being sure that channel is idle [2].