Performance analysis of an alternative link-16/JTIDS waveform transmitted over a channel with pulse-noise interference

Abstract

The Joint Tactical Information Distribution System (JTIDS) is a hybrid frequency-hopped, direct sequence spectrum system that utilizes a (31,15) Reed-Solomon (RS) code and cyclical code-shift keying modulation for the data packets, where each encoded symbol consists of five bits. The primary drawback to JTIDS is the limited data rate. In this paper, an alternative waveform compatible with the existing JTIDS channel waveform but with a two-fold increase in data rate is analyzed. The system to be considered uses (31,15) RS encoding as in the original JTIDS, but each pair of five-bit symbols at the output of the Reed-Solomon encoder undergoes serial-to-parallel conversion to two five-bit symbols, which are then independently transmitted on the in-phase and quadrature components of the carrier using 32-ary biorthogonal keying with a diversity of two. The performance obtained for the alternative waveform is compared with that obtained with the existing JTIDS waveform for the relatively benign case where additive white Gaussian noise (AWGN) is the only noise present as well as when pulse-noise interference is present. Errors-and-erasures decoding (EED) as well as errors-only decoding are considered. Our analyses show that the proposed alternative JITDS waveform performs better in the presence of AWGN as well as both AWGN and pulse-noise interference. There is no significant advantage to using EED with the alternative waveform as compared to errors-only decoding.