THROUGHPUT RETURNS DUE TO ADAPTIVE MODULATION TECHNIQUES

Abstract

Adaptive modulation is a powerful technique to increases the throughput of a wireless network by adjusting the modulation scheme to the channel status. We investigate the throughput returns due to the employments of adaptive modulation techniques (MPSK:M-ary Phase Shift Keying or MQAM:M-ary Quadrature Amplitude Modulation). In this project, the Bit Error Rate (BER) performance and spectral efficiency of a coded adaptive modulation technique over a multipath fading channel (no fading, flat fading and dispersive fading) will be implemented. By using simuation, we find out that the SNR increased because higher modulation technique is use. While SNR decrease when the lower modulation technique is use.
For this case, when SNR>8dB, bit rate is 54Mbps, the 64QAM ¾ is apply and when SNR<1, bit rate is 6Mbps, the BPSK ½ is implement. This results in good data rates in the system. Therefore, Adaptive modulation systems offer a significant throughput and/or power gain compared to non-adaptive transmission, particularly when the channel conditions are slowly time varying and a reliable feedback channel is available.