SIMULASI PERBANDINGAN KINERJA MODULASI M-PSK DAN M-QAM TERHADAP LAJU KESALAHAN DATA PADA SISTEM ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM)

Abstract

OFDM (Orthogonal Frequency Division Multiplexing) is a transmition technique which uses some orthogonal subcarrier frequencies (multicarriers). Each of the subcarrier is modulated by conventional modulation technique at low symbol ratio. It can be a Phase Shift Keying (PSK) modulation and Quadrature Amplitude Modulation (QAM). A simulation in this final project is made with Matlab 7.1. The purpose of the simulation is to analyze M-PSK and MQAM modulation effects in OFDM system for AWGN channel, nonlinear distortion channel and also distortion clipping. OFDM system performance in AWGN channel is observed by analyzing Bit Error Rate (BER) values and Energy per Bit to Noise Power Spectral Density Ratio (Eb/No) received by OFDM receiver by varying channel Eb/No value. Meanwhile, OFDM system performances in nonlinear distortion channel and also distortion clipping have additional parameter that is Input Back-off (IBO). The results show that the lower modulation level the better system performance against noise. In AWGN channel, OFDM system with M-QAM modulation has better performance than M-PSK OFDM system. It can be known based on BER values of M-QAM OFDM system that reach zer value faster than M-PSK OFDM system. In nonlinear distortion channel, M-PSK OFDM system has better performance than M-QAM OFDM system,but after having distortion clipping M-QAM OFDM system has better performance than M-PSK OFDM system. Keywords: OFDM, M-PSK, M-QAM, BER, Eb/No, IBO