Hadamard Matrix based Selected Mapping Hybridized with Clipping Technique for Peak to Average Power Ratio Reduction in OFDM System using Several Sub-carriers

摘要

High Peak to Average Power Ratio (PAPR) introduces distortion in the information when MultiCarrierModulation (MCM) technique like Orthogonal Frequency Division Multiplexing(OFDM) is used. OFDM is generally preferred when higher data rates are required. So it has become a requirement for the system which is using OFDM to diminish PAPR problem. So, in this paper we are proposing a novel technique in which we are using Selected Mapping (SLM) with clipping technique under Hadamard matrix based phase sequence designed in frequency domain. In the conventional SLM technique which uses multiple phase sequence possessing same length as that of the data sequence in order to diminish PAPR. Therefore, it is highly demanded that we have to propose a technique by which we can design phase sequence in frequency domain easily and can optimized the results in time domain. So, we have implemented an algorithm which design phase sequence in frequency domain conveniently and after transformation through inverse Fast Fourier Transform (IFFT) optimize in time domain accordingly. Along with this, we have hybridized clipping technique in time domain so that if in any case PAPR problem is found to be greater than certain threshold then it can clip it in the time domain sequence domain itself. Simulation results clearly provide the justification and efficiency of proposed algorithm as compared with conventional OFDM, SLM and Clipping technique. Proposed novel algorithm attains a significant gain (dB) of 2.85,2.65,2.35,2.05,2.60 and 2.70 in comparison with conventional OFDM system considering several number of sub carriers (N)=32,64,128,256,512 and 1024 respectively.