We introduce DCT SLM orthogonal frequency coded division multiplexing (OFCDM) scheme for reduction of peak to average power ratio. There is a time for high-speed data transmission in mobile communications. OFCDM is very promising technique for 4G standard like LTE (Long Term Evolution) and WIMAX (Worldwide Inter-operability for Microwave Access) but also has some issues like frequency-offset and PAPR (peak-to-average power ratio). High peak-to-average power ratio (PAPR) of the transmitted signal originates from the superposition of many independent subcarriers. In this paper, a Discrete Cosine Transform based modified selective mapping technique is proposed to reduce the PAPR of the transmitted signal. This method combines Discrete Cosine Transform (DCT) with modified Selective Level Mapping (SLM), the variant of SLM make use of the standard array of linear block codes. The proposed method can be realized in two ways- scheme 1 and 2. In scheme1 DCT is used before the IFFT block in Modified SLM and in scheme 2 DCT is used after the Modified SLM block. Simulation results shows that Scheme 1 is having better reduction performance than the scheme 2. Due to PAPR reduction ICI and ISI both reduces drastically.

1. Ms. Jobin Raj and Mr. M. Malleswaran, "DCT Based Modified SLM Technique for PAPR Reduction in OFDM Transmission". (IJSER), ISSN: 2229--5518 Vol. 3,June 2012.
2. Syed M. Zafi S. Shah, Umrani A. W. , MemonAftab A. , "PMEPR Reduction for OFCDM using SLM and PTS" 2012 IEEE
3. VB Shukla, Manish Panchal and Yan L. D. Malwiya,"Peak-to-Average Power Reduction in OFCDM System to Enhance the Spectral Efficiency" Conference ( 2006)
4. Imran Baig and Prof. VarunJeoti. "DCT Precoded SLM Technique for PAPR Reduction in OFDM System". 2010 IEEE
5. Dae-Woon Lim, Jong- Seon No, Chi-Woo Lim and Habong Chung, "A New SLM OFDM Scheme With Low Complexity for PAPR Reduction"IEEE Signal Processing Letters. Vol. 12, No. 2, Feb 2005
6. Zhou, Y. , Ng, T. -S. , Wang, J. , Higuchi, K. Sawahashi, M. : 'OFCDM: a promising broadband wireless access technique', IEEE Commun. Mag. 2008.
7. Tao Jiang, Yiyan Wu, Fellow, "An Overview: Peak-to-Average Power Ratio Reduction Techniques for OFDM Signals" IEEE Transaction on Broadcasting, Vol. 54, No. 2, June 2008
8. ArunGangwar, ManushreeBhardwaj, "An Overview: Peak to Average Power Ratio in OFDM system & its Effect" (ILCCTS) Vol 01- No. 2. Issue: 02 September 2012
9. Radheshyam Patel, ChiragPrajapati, Vishal Naik, Prof. T. P. Dave, " PAPR Reduction Techniques in OFDM system" (IJCST) – Vol 2 Issue 1, Jan-Feb 2014
10. SachinDogre, Jyoti Gupta, "Performance Analysis of PAPR Reduction in OFDM Signals By Using SLM, PTS and Iterative Flipping Technique with Their Comparison to Original Signal" (IJIRS) ISSN-2319-9725, Vol 3, Issue 4.
11. Nasaruddin, Melinda, EllsaFitria Sari, "A Model to Investigate Performance of Orthogonal Frequency Code Division Multiplexing "TELKOMNIKA, Vol. 10, No. 3, July 2012, pp. 579~585.

Dct Dct Slm Modified Slm Papr Slm