Study Theapplication Of Polar Codes In OFDM Systems Of Image Transmission

Polar codes, first proposed by Arikan in 2007, is a new channel encoding method based on channel polarization theory. Polar codes can achieve the channel capacity with a low encoding and decoding complexity. In this paper, we have studied the performance of Polar Code in image transmission and Orthogonal Frequency Division Multiplexing(OFDM) system.In image transmission, we discussed the effect of the decoding iterations times, code length, bit rate and the system input Signal-to-noise ratio (SNR) of Polar codes to image reconstruction. Then we compared these results to the performance of Low Density Parity Check Code(LDPC) in image reconstruction under the same condition. The numerical simulations show that the frame error ratio (FER) of image transmission decreases and the Peak Signal to Noise Ratio (PSNR) increases.with the increase of decoding iterations times, code length and the decrease of bit rate. For example, for the Additive White Gaussion Noise (AWGN) channel, the PSNR will be greater than 40dB, when the code length is 2048, the bit rate is 0.25, the number of iterations is 120, and the SNR is greater than -1dB. Meanwhile, we compared the performance of Polar Code with those of LDPC codes in the same image transmission system. The result shows that the performance of Polar Code is better than LDPC when the code length is long.Later, we studied the performance of Polar Code in Orthogonal Frequency Division Multiplexing (OFDM) system for image transmission. We diccussed the effect of the decoding iterations, code length, bit rate and the system input SNR on Polar Code Orthogonal Frequency Division Multiplexing(Polar-COFDM) system. We compared the result to the performance of LDPC-COFDM system. The simulation results show that the Polar-COFDM system performance is better with the increase of decoding iterations times, code length, and the decrease of bit rate. Comparison of Polar Codes and LDPC codes, we found the Polar performance is better than LDPC codes when the code length is longer with smaller bit rate. When the code length is 2048 or 4096, the Polar code error rate compared to LDPC codes were better. Meanwhile Studied the application of Polar codes in OFDM systems of Image Transmission.In the same conditions of Polar codes and LDPC codes, the Polar Code of image transmission frame error rate is less than the LDPC codes, while its PSNR value is greater than the LDPC codes. It indicates that in the COFDM transmission images, the performance of the Polar code system is better than LDPC codes.