Concatenated eIRA Codes for Tamed Frequency Modulation

A new scheme of the extended irregular repeat- accumulate (eIRA) coded tamed frequency modulation (TFM) for deep space communications is introduced in this paper. It is mainly based on the optimal concatenation of the eIRA code and the continuous phase encoder (CPE) decomposed from TFM. In order to obtain good performance of the eIRA coded TFM, the main principle of our scheme is to jointly optimize the concatenation by eliminating the short loops in the Tanner graph of the eIRA code and the coding part of TFM and to jointly decode between them. Then our scheme without interleaving and the contrast scheme with interleaving are simulated in an additive white Gaussian noise (AWGN) channel which is typical in deep space communications. Simulation results have shown that our scheme can obtain lower complexity and less decoding delay (due to the reduction of interleaving) at the cost of just 0.1-0.15 dB performance loss when compared to the scheme with interleaving given bit-error-ratio (BER) of 10 5. Therefore, our scheme can be used to implement the coded TFM system for deep space communications with good performance and low complexity.