This book studies the coexistence performance of low rate wireless personal area networks (LR-WPANs) such as Bluetooth (IEEE 802.15.1) and ZigBee (IEEE 802.15.4). The main goal of this book is to describe the performance of LR-WPAN under erroneous environments due to the interference and/or error-prone wireless channel property. Wireless medium is error-prone. Especially both LR-WPAN standards define 2.4 GHz industrial scientific medical (ISM) band as a physical layer, therefore, there are many interference sources such as IEEE 802.11 WLAN. Hence, the performance analysis in erroneous environments is required. In this book, performances of coexisting wireless networks are analyzed by means of mathematical modelings and simulations. Packet error rate (PER), throughput, and transmission delay are used as performance measures. The result of this book can suggest the coexistence criteria among ZigBee, WLAN, and Bluetooth. It will be useful to design and implement a network using ZigBee, WLAN, and Bluetooth altogether.