Ignited by mobile phone huge success at the end of last century, the demand for wireless services is constantly growing. To face this demand, wireless systems have been and are deployed at a large scale. These include mobility-oriented technologies such as GPRS, CDMA or UMTS, and Local Area Network-oriented technologies such as WiFi. The next step in wireless communications is broadband wireless access systems, which provides ubiquitous Internet and large bandwidth. In order to create conditions for an efficient technology, addressing interoperability and competition in this promising market, a standardization effort has been led by the Institute of Electrical and Electronic Engineers (IEEE). The first released standard was the IEEE 802.16, which addresses a wide range of frequencies, and defines the main principles for the series of the IEEE 802.16 fixed wireless and mobile standards published afterwards. The advanced air interface of IEEE 802.16m will enable multi-hop relay architectures, roaming and seamless connectivity across IMT-advanced and IMT-2000 systems through the use of appropriate interworking functions. WiMAX Networks covers aspects of WiMAX quality of service (QoS), security, mobility, radio resource management, multiple input multiple output antenna, planning, cost/revenue optimization, physical layer, medium access control (MAC) layer, network layer, and so on.