Performance of LDPC codes in wideband shortwave channel

To reduce the effect of multi-path and Doppler on the bit error rate performance in the shortwave broadband channel, LDPC code with probable checking matrix and an improved decoding algorithm is introduced to ensure the reliability of the system as channel encoding. Combined with MC-CDMA technology which can inhibit the multi-path interference effectively, the LDPC+OFDM+DSSS scheme is proposed. Using the equalization techniques to recover received signals, the simulation model is built by the analysis of shortwave broadband channel based on ITS model. Simulation results show that: the program not only can inhibit the symbol interference effectively, but also can reduce the sensitivity of the communication system to Doppler frequency and reach a better bit error rate performance.