Performance of PAPR Reduction in OFDM System with Complex Hadamard Sequence using SLM and Clipping
Reshma Elizabeth Regi1, Haris P.A.2
1Reshma Elizabeth Regi,  Electronics and Communication Engineering, College of Engineering, Trivandrum, India.
2Dr. Haris P.A.,  Electronics and Communication Engineering, College of Engineering, Trivandrum, India.
Manuscript received on March 21, 2014. | Revised Manuscript received on April 16, 2014. | Manuscript published on April 30, 2014. | PP: 381-384  | Volume-3, Issue-4, April 2014. | Retrieval Number:  D3028043414/2013©BEIESP

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Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is an efficient method of data transmission for high speed communication systems. However, the main drawback of OFDM system is that, it exhibits high Peak to Average Power Ratio (PAPR) of the transmitted signals. OFDM consist of large number of independent subcarriers, as a result of which the amplitude of such a signal can have high peak values. The Selected Mapping (SLM) technique is one of the promising PAPR reduction techniques for OFDM. This technique however increases the computational and phase search complexity and PAPR reduction performance is largely dependent on the selection of random phase sequences. In this paper, a new SLM method which rotates the phase of input data after IFFT by using matrices generated from complex Hadamard code is proposed. After phase rotation, clipping technique is used to further reduce the PAPR. From simulation results, we can find that the proposed method has lower PAPR than conventional SLM combined with clipping technique.
Keywords: OFDM-Orthogonal frequency division multiplexing, Clipping, SLM-Selected Mapping, Hadamard Sequence.