PAPR Reduction in OFDM System using Adapting Coding Technique with Pre distortion Method CHHAVI SHARMA 1 , SHIV KUMAR TOMAR 2 , A.K.GUPTA 3 MJP Rohilkhand University, Bareilly , India 1 Maya Institute of Technology and Management, Selaqui, Dehradun, India 2 National Institute of Technology, Kurukshetra, India 3 Email: yash_naina@yahoo.co.in, shivktomar@gmail.com,anilg699@rediffmail.com Abstract: - In this paper we propose the Peak to Average Power ratio reduction (PAPR) in OFDM using adapting coding technique with pre-distortion method to decrease the nonlinear distortion and to improve the power efficiency of the non-linear high power amplifier (HPA). In the proposed method adaptive coding is used for error correction as well as PAPR reduction. The pre-distorter improves the bit error rate performance of the system. Key-Words: - Complementary cumulative distribution function (CCDF), Peak to average power ratio (PAPR), High power amplifier (HPA), Orthogonal frequency division multiplexing (OFDM). 1 Introduction Orthogonal frequency division multiplexing (OFDM) is a strong candidate for future wireless communication because it is marked by its higher frequency multiplicity and greater immunity to multipath fading. The OFDM based physical layer has been chosen for several wireless standards such as digital audio broadcasting (DAB), digital video broadcasting (DVB-T), the IEEE 802.11a [1] local area network (LAN) standard and the IEEE 802.16a [2] metropolitan area network (MAN) standard. However, one of the problems in OFDM system is peak to average power ratio (PAPR) of the transmitted signal. Several techniques have been proposed for reducing PAPR, such as clipping method, coding method, SLM and PTS. Clipping method is used to clip the peak above a certain prescribed level. The merit of this clipping method is that PAPR can be easily reduced, but the BER performance becomes poor due to many defected signals [4, 5]. SLM (Selected Mapping) and PTS (Partial Transmit Sequence) are considered two main phase control schemes to escape the high peak. In SLM, one signal of the lowest PAPR is selected as a set of several signals containing the same information data. In PTS, the lowest PAPR signal is achieved by optimally phase combining technique. Both techniques are very flexible scheme and have a better performance of the PAPR reduction without any signal distortion, however, they require more system complexity and computational burden by using many IFFT blocks. Coding is another important method for PAPR reduction. This method performs the error correction as well as to control PAPR [1-4], but main problem is to exhaustively search for effective codes, store large look-up tables & large computations. In this paper, the author proposed adaptive coding technique with Pre- distortion. Coding technique is used for WSEAS TRANSACTIONS on COMMUNICATIONS Chhavi Sharma, Shiv Kumar Tomar, A. K. Gupta ISSN: 1109-2742 255 Issue 9, Volume 10, September 2011