Performance Evolution of GTS Based Wireless Sensor Networks under CSMA/CA with Variable Clear Channel Assessment Exponent

Wireless Sensor Networks forms an integral part of modern society. These are the networks that form the backbone of various types of modern aminities whether it is automatic fire fighting system, theft alarm, wildlife habitat monitoring or the real time adjustable temperature and humidity controller of an air flow system in a mall. The physical and MAC layer specifications for WSN are specified in IEEE 802.15.4 specifications. For real time wireless sensor networks, the underlying MAC layer data transmissions comes with GTS or Guaranteed Time Slots so that the time critical packets can be delivered to the destination with bounded delays. However, the mechanism followed for contention access period is CSMA with CD and CA in diversified implementations. The CCA is the most critical aspect of CSMA/CA. This paper attempts to model the throughput and performance of MAC under GTS and various values of backoff exponent for Clear Channel Assessment.