Worldwide Interoperability for Microwave Access often termed as WiMax is an effective OFDM based technique used for providing last mile connectivity to end users specifically in a wireless network. Wireless Fidelity is fundamentally limited by communication range and data rate which is overcome by WiMax systems. However due to the large coverage area of WiMax, it is susceptible to distortions created by the non-ideal nature of wireless channels. This results in Bit Error Rate degradation of the wireless system, thereby degrading the Quality of Service (QoS). This paper presents the basics of WiMax Systems, the main challenges faced by WiMax based systems and techniques or methodologies to overcome the challenges to enhance system performance.