Saroj Singh Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 7( Version 4), July 2014, pp.120-124 www.ijera.com 120 | Page Performance Comparision of Coded and Un-Coded OFDM for Different Fic Code Saroj Singh 1 , Sagar Singh Rathore 2 1 PG Scholar, Department of Electronics & Telecommunication Bhilai, Chhattisgarh, India 2 Assistant Professor, Department of Electronics & Instrumentation Bhilai, Chhattisgarh, India Abstract - Error correction and detection in digital communication is used to compensate the bit error rate introduced during transmission of data. In this paper the investigation has been made to the performance of some error detecting and correcting coding algorithm for OFDM system. Convolution code, RS code and linear block code based OFDM system has been implemented, studied and analyzed. Simulation is performed in MATLAB environment. Keywords- Convolution code, Reed Solomon code, SNR, BER, AWGN ,QPSK I. INTRODUCTION The transmission of signal from one place to other without wire is termed as wireless communication. Now a day’s wireless communication is replacing wired communication very rapidly due to its reduced cost, efficiency, flexibility, and mobility[1]. Due to its popularity, a lot of research is being done in this field to make it more and more effective for transmission [2]. The wireless communication system consist of Source, Source encoder/decoder, channel encoder/decoder, modulator/demodulator and communication channel. Source block provides the information which is to be sent. It may be speech signal, text or video. The source encoder/decoder block convert this source data into digital format. Channel encoder/decoder block[3] append some extra bit into the signal for correcting the error introduced in the signal due to fading or noise addition[4][5]or inter symbol interference[6]. Figure 1 Wireless communication system Modulator/demodulator block perform the modulation/ demodulation operation while the channel block represent the characteristics of communication channel like fading, interference, noise etc. Frequency division multiplexing (FDM), Time division multiplexing (TDM), Code division multiplexing(CDM)[7] are some of the multiplexing techniques used earlier in wireless communication . Later on these multiplexing were replaced by spectral efficient multiplexing technique OFDM [8]. Since in OFDM, the data of high bit stream is converted to different low bit stream data sent in parallel fashion therefore it shows better immunity over inter symbol interference (ISI). But since data is sent in different sub carrier therefore it also faces the problem of fading or multipath along with the noise. Channel coding or error correction codes [9][10] are generally used with OFDM to combat the problem of fading ,ISI and noise. A lot of various techniques have been proposed in the past for error correction [11]. It is very important for the researcher to know how these techniques perform in fading and noisy environment. This paper presents a performance evaluation of three most important error correction techniques i.e. Reed Solomon code and convolution code and linear block code [12][13][14] under fading and noisy environment. II. CHANNEL CODER/DECODER In order to fight the error introduce during the transmission due to multipath phenomenon, ISI and noise an appropriate coding of signal is necessary. This job is performed by the channel coder/ decoder block in communication system. Generally for coding/encoding purpose, Forward error correction code (FEC) [15]is mostly used in digital communication system. Error correction techniques generally work by introducing some redundancy RESEARCH ARTICLE OPEN ACCESS