The effects of AMC-AMS to mobile WiMAX system quality

The movement of the users may decrease the quality of the information signal because this movement can affect the channel propagation conditions in unpredictable manner. This case can be occured on mobile WiMAX (IEEE 802.18m) system. Mobile WiMAX is able to serve users with high mobility. The capability of the system to serve users with high mobility should be balanced with a quality of the information signal. To overcome this problem, AMC (Adaptive Modulation and Coding) can be applied. Applying AMC technique, the quality of the information signal can be maintained. Another way to overcome these problems is the application of different types of MIMO or AMS (Adaptive MIMO Switching). Implementation of combination techniques of AMC and AMS in mobile WiMAX systems was able to improve system performance in terms of BER and SNR. When the user velocity was 3 km/hr, to achieve a BER of 10^-3 with AMC-AMS system required a SNR of 55.37 dB. When the uservelocity of 60 km/hr, to achieve a BER of 10^-3 with AMC-AMS system required a SNR of 58.47 dB.