Performance analysis of concatenated BCH and convolutional coded OFDM system

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a widely used technique for wireless communications. But uncoded OFDM is not sufficient by itself, that is why channel coding is included to increase the system performance. In this study, concatenated Bose Chaudhuri Hocquenghem (BCH) and Convolutional Coded (CC) OFDM system is investigated for multipath fading channel with Additive White Gaussian Noise (AWGN). The simulation results show that the proposed concatenated code needs lower Signal-to-Noise Ratio (SNR) when compared with single BCH code, single convolutional code and even with other concatenated systems. Throughout the simulations BCH coding is performed with 128, 256, 512 Fast Fourier Transform (FFT) lengths; whereas convolutional coding is performed with 1/2, 1/3 coding rates. Furthermore, interleavers are added to the system to prevent the burst errors that occur over the channel. With the proposed system, the best result is obtained by using BCH(511,340) and CC(3,1,7) concatenation which is 8.2 dB SNR value for 10(-3) Bit Error Rate (BER). This result is very close to ideal AWGN channel value, which is 8 dB for 10(-3) BER.