Forward error correction codes (FEC) are used for error detection and correction in communication systems. Low density parity check code (LDPC) is used as a powerful Forward Error Correction code in long distance communication systems which works close to the Shannon limit. Unlike other conventional channel code, the decoding algorithm used for LDPC codes is an iterative message passing algorithm (MPA). They are soft decision and hard decision decoding algorithms. This paper aims at a comparative study between a hard decision algorithm (bit flipping) and a soft decision algorithm (belief propagation). The analysis is based on the Bit Error Rate of decoding outputs. The result shows that the Soft decision decoding gives better performance than the hard decision decoding. LDPC code with soft decision decoding enhances the system performance and makes the long distance communication fast and error free.

1. Michel Zorzi, Performance of FEC and ARQ Error Control IN Bursty Channel Under Delay Constraints, VTC'98, OTTAWA Canada May 18-21, 1998.
2. C E Shannon, A Mathematical Theory of Communications, Bell Systems Technology Journal, pages 379-423, 623-657, 1948.
3. R. G Gallager, Low Density Parity Check Codes, IRE Transactions on Information Theory, vol-8. no. 1, pp21-28, January 1962.
4. Aqiel N. Almaamory, HusamAbduldaem Mohammed, PerformanceEvaluation and Comparison Between LDPC and Turbo Coded MCCDMA, Journal of Engineering, vol. 18, no. 8, April 2012. , 2nd ed. , January 2002
5. European telecommunications standards institute, digital video broadcasting (dvb) second generation framing structure for broadband satellite applications, Pages 302-307 v1. 1. 1. , URL: www. dvb. org
6. B. Vasic , Ivan B. Djordjevic, Low density parity check code and iterative decoding for long haul optical communication system,Journal of light wave technology , vol. 21. no. 2. February 2003
7. M. M Jadhav, AnkitPancholi, Dr. A. M Sapkal, Analysis and Implementation of Soft Decision Decoding Algorithm of LDPC ,International Journal of Engineering Trend and Technology(IJETT)- Vol4, Issue6, June 2013
8. Tuan Ta, A Tutorial on Low Density Parity Check Codes, The University of Texas at Austin
9. D. Mackay, R. Neal, Near Shannon Limit Performance of Low-Density Parity Check Codes , Electronics Letters, 32(18):1645-1646, August 1996
10. Sarah. J. Jhonson, Introducing Low-Density Parity Check Codes, The University of Newcastle, Australia
11. T. J Richardson, M. A Shokrollohi and R. L Urbanke, Design of Capacity Approaching Irregular Low Density Parity Check Codes, IEEE Trans. Inform. Theory, Vol. 47, no 2, pp 619-637, Feb 2001
12. R. M Tanner, A Recursive Approach to Low Complexity Codes,IEEE Transaction on Information Theory, IT 27(5):533-547, Sep 1981
13. Namrata P. Bhavsar, BrijeshVala, Design of Hard and Soft Decision Decoding Algorithms of LDPC, International Journal of Computer Applications (0975 8887) Volume 90 No 16, March 2014.
14. Lakshmi. R, Tilty Tony, Abin Johns Raju, An Analytical Approach to The Performance of Low Density Parity Check Codes, International Conference on Advanced Computing and Communication Systems (ICACCS -2013), Dec. 19 21, 2013
15. VikramArkalgudChandrasetty, Syed Mahfuzul Aziz, FPGA Implementation of a LDPC Decoder using a Reduced Complexity Message Passing Algorithm , Journal of Networks, Vol. 6, no. 1, January

Ldpc Fec Lbc Iterative Decoding Ber Sum Product Decoding Message Passing Algorithm.