In recent years, Wireless Local Area Networks (WLANs) has become a promising and successful technology. It provides free wireless connectivity between two or more devices by using a wireless communication method. It offers an easy and viable access to the network. The initial version of WiMAX 802.16-2004 operated at high frequency range use certain type of antenna mounted on WiMAX base station and subscriber station to provide data in line of sight manner. To overcome these limitations we use scalable OFDMA with MIMO technology to support wide range of bandwidth by varying the size of FFT. In this book, MATLAB coding is used to calculate the bit error rate for different extensions of IEEE 802.11 and IEEE 802.16e system model that minimize the number of communication errors. Here we have used different modulation schemes and OFDM technique to obtain higher data rate and achieve best bit error rate. It represents simulation result of IEEE 802.11 extensions and 802.16e PHY layer model.