The IEEE 802.16m standard of the Worldwide Interoperability for Microwave Access (WiMAX) was accepted as a 4G standard in 2011. The IEEE 802.16m is fully optimised for fixed wireless communication environments and can deliver very high throughput and excellent quality of service. However, in mobile communication environments the WiMAX quality of service experiences a graceful degradation as a direct function of the speed of mobile nodes. Unless some proactive measures such as forward error control and packet size optimisation are adopted and properly adjusted, many applications cannot be supported in WiMAX at high vehicular speeds. Bit error estimation as a function of vehicular speeds serves as a useful tool for any proactive measure. This book presents an analytical model for bit error estimation in WiMAX communications using the Nakagami-m fading model. This book also shows that the Nakagami-m model can be made adaptive as a function of speed to represent fading in a fixed environment as well as in a mobile environment.