Comparison of Error Performance of Discrete Wavelet Transform Based Cyclic Coding Method in Different Type Channels

摘要

Forward Error Correction (FEC) is a technique used to increase the reliability of data transferred over noisy communication channels and provides error control. In this technique, the data is now used for error checking before the data is transmitted. Cyclic Coding is one of the FEC techniques used for data coding and decoding in communication systems. Discrete Wavelet Transform (DWT) is also used extensively in digital signal processing applications. In the first part of this study, Cyclic Coding Method is used in order to transmit the audio data recorded in .wav format for 5 s in the MATLAB environment with the minimum error possible. As a modulation method, Binary Phase Shift Keying (BPSK) modulation is used. In the communication system created, two types of channels are used: Addition White Gaussian Noise (AWGN) and Rician fading channels. These channels are coded with Cyclic (7,4), Cyclic (15,7), Cyclic (17,8), and Cyclic (23,12) codes respectively. Then, the Mean Square Error (MSE) performances of these encodings are analyzed. In the second part of the study, it is investigated which wavelet family is suitable in the communication system which was designed to transmit sound with minimum error. Four wavelet transform families at different levels are applied to the audio signal for Cyclic (7,4), Cyclic (15,7), Cyclic (17,8) and Cyclic (23,12) coded channels and the transmission performances are compared. According to the results obtained in the simulations, the best results for both the DWT state and the non-DWT state and for both channel types are obtained for Cyclic (23,12). The codes longer than this code have not been used in this study due to their unacceptable disadvantages in computing costs and bandwidth.