PAPR reduction using combination of precoding with Mu-Law companding technique for MIMO-OFDM systems

Key challenges for future wireless communications (4G) are bandwidth efficient system which provides high data rate with lower bit error rate and it also eliminate the multipath fading. MIMO-OFDM technology is the promising technique to provide high data rate with lower bit error rate and also improves the channel capacity under multipath fading environment. But the main drawback of OFDM system is high peak-to-average power ratio (PAPR), whenever all the orthogonal signals are added at a maximum point the resultant peak power will be increased. Several techniques are proposed to reduce PAPR viz. Coding, Interleaving, selected level mapping, partial transmit sequence, tone reservation. In this paper Unitary matrix precoding with companding technique is proposed to reduce PAPR. Simulations are performed by using MATLAB tool; results are analyzed for different systems (uncoded, precoding, companding and precoding with companding). Results demonstrate that unitary matrix precoding with companding technique is an efficient technique to reduce PAPR by maintaining optimum BER.