An analysis of BER comparison of various digital modulation schemes used for adaptive modulation

In this paper, a comparative analysis of BER performance of various higher order digital modulation techniques for channel utilization is proposed and the analysis are carried out with SNR as the reference parameter. This performance analysis yields to adaptive modulation technique which can be used to attain high spectral efficiency by modulating the signal at higher order modulation schemes based on channel state information (CSI) from the receiver. Signal over AWGN channel is assumed for the analysis. To achieve lower BER values for a specific SNR, techniques to alter signal characteristics like pulse shaping filters, matching filters and convolution encoding are applied and analysis are carried out. An observation from the above analysis produces lower BER. For 256-QAM at SNR of 20, BER of 4.76×10-3 and grey coded BER of 3.83×10-4 is obtained. Highest possible modulation technique is selected with lower BER obtained. Thus, spectral efficiency which is the prime objective of the proposed paper is achieved. The above results are computed and simulated using MATLAB.