Date Added: Jun 2011
The unlicensed ISM spectrum is getting crowded by WLAN and WPAN users and devices. Spectrum sharing within the same network of devices can be arbitrated by existing MAC protocols, but the coexistence between WPAN and WLAN (e.g., ZigBee and Wi-Fi) remains a challenging problem. The traditional MAC protocols are ineffective in dealing with the disparate transmit-power levels, asynchronous time slots, and incompatible PHY layers of such heterogeneous networks. Recent measurement studies have shown moderate-to-high Wi-Fi traffic to severely impair the performance of coexisting ZigBee.