ACK with Interference Detection Technique for ZigBee Network under Wi-Fi Interference

Recent studies have shown that the low-power ZigBee based wireless sensor networks (WSN) are vulnerable to the interference of Wi-Fi wireless local area networks (WLAN). From our experimental studies on this coexistence issue, it is found that there are a large number of acknowledgement (ACK) packet losses in the ZigBee packet transmission process, which, in turn, generates large number of unnecessary packet retransmissions, wasting precious channel bandwidth and energy. To address this issue, in this paper, a novel technique named ACK with Interference Detection (ACK-ID) that can effectively reduce the ACK losses and consequently reduce ZigBee packet retransmissions is proposed and implemented in the Crossbow MICAz motes of our testbed. The experimental performance evaluation results show that the proposed ACK-ID can significantly improve the performance of ZigBee packet transmission in terms of ACK delivery rate and packet retransmission rate while operating under interference from the collocated WLAN.