Performance of a JTIDS-type waveform with noise-normalization combining in pulsed-noise interference

The Joint Tactical Information Distribution System (JTIDS) is the communication terminal of Link-16. When the double-pulse structure is chosen to transmit the Link-16 data, JTIDS is a hybrid direct sequence/fast frequency-hopping spread spectrum system with a sequential diversity of two. To minimize the effect of pulsed-noise interference (PNI), a noise-normalized diversity combining MSK chip demodulator is assumed in the JTIDS receiver. The symbol error rate (SER) performance of a coherently detected JTIDS-type waveform for the double-pulse structure with noise-normalization combining (NNC) in PNI is investigated in this paper. To facilitate the evaluation, perfect frequency de-hopping, sequence synchronization, chip synchronization, and 32-chip sequence descrambling are assumed. Furthermore, maximum-likelihood chip detection is assumed rather than maximum-likelihood chip-sequence detection since the former represents a more practical assumption for a JTIDS signal. The results obtained with NNC are compared to those without NNC, as well as to those with perfect side information. The results show that for a coherently detected JTIDS-type waveform with the double-pulse structure, NNC effectively mitigates the system degradation caused by PNI.