Impact of Clear Channel Assessment Mode on the Performance of ZigBee Operating in a WiFi Environment

ZigBee is a standard optimised for radio networks used in applications such as interconnecting sensors, monitoring and automating home, medical, industrial, and agricultural systems where low levels of data throughput and low-power consumption are needed. The physical (PHY) and medium access control (MAC) layers of ZigBee are defined by the IEEE 802.15.4 standard. One of the operational frequency bands of ZigBee is the unlicensed 2.4 GHz Industrial, Scientific and Medical (ISM) band which is also used by WiFi. Several ZigBee and WiFi devices may operate in the same environment, which may result in the two systems performance degradation. Before transmitting, WiFi and ZigBee devices perform the clear channel assessment (CCA) according to three different modes defined in the standards. In this paper, ZigBee throughput is obtained for the different CCA modes used by both ZigBee and WiFi systems operating in the same environment. Simulation results show that, ZigBee performance can be optimised by choosing the suitable CCA mode with respect to the interference level at the receiver