Performance Analysis of the Link-16/JTIDS Waveform with Concatenated Coding, Soft Decision Reed-Solomon Decoding, and Noise-Normalization

摘要

The Joint Tactical Information Distribution System (JTIDS) is a hybrid frequency-hopped, direct sequence spread spectrum system that employs a (31, 15) Reed-Solomon (RS) code for forward error correction coding. In this thesis, an alternative error correction coding scheme that uses concatenated coding with a (31, k) RS inner code and a rate 4/5 convolutional outer code is considered. In addition, a sequential diversity of two, consistent with the JTIDS double-pulse structure, is considered both for soft decision (SD) RS decoding and for soft diversity combining with noise-normalization. Both coherent and noncoherent detection are considered. Based on the analyses, the alternative JTIDS waveform outperforms the original in all cases considered. When only additive white Gaussian noise is present, the best performances, which result in a gain of about 1.4 dB relative to the existing JTIDS waveform, are achieved for (31, 23) RS and (31, 25) RS inner codes for coherent detection and for (31, 27) RS and (31, 29) RS inner codes for noncoherent detection. For these RS inner codes, a 23.0% and 33.0% improvement in system throughput is achieved, respectively, for coherent detection, and a 44.0% and 55.0% improvement in throughput is achieved, respectively, for noncoherent detection relative to the existing JTIDS waveform. Noise-normalization neutralizes the effects of pulse-noise interference, but no significant benefits are obtained from using SD RS decoding.