General purpose of this lecture is to describe 4G Mobile Communications; major focus on WiMAX and LTE. This lecture focus on overview of IEEE 802.22 Standard and comparison of 3G and 4G. Wi-MAX is the Worldwide Interoperability for Microwave Access, is a technology aimed at providing wireless data over long distances. It is based on the IEEE 802.16 standard. Here also describe on WiMAX applications and missions, Long Term Evolution (LTE) and Architecture of LTE.