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<p>Link-16 is a tactical data link currently employed by the United States Navy, the  Joint Services, and forces of North Atlantic Treaty Organization. It provides presumably  secure and jam-resistant tactical information for land, sea, and air platforms. The  communication terminal of Link-16 is called Joint Tactical Information Distribution  System (JTIDS) and features Reed-Solomon (RS) coding, symbol interleaving, cyclic  code-shift keying (CCSK) for M-ary symbol modulation, minimum-shift keying for chip  modulation, and combined frequency-hopping and direct sequence spread spectrum for  transmission security. In this dissertation, we investigate the performance of a  JTIDS/Link-16-type waveform in both additive white Gaussian noise (AWGN) and  narrowband interference when the signal is transmitted over a slow, flat Nakagami fading  channel. In general, the results show that barrage noise interference has the most effect in  degrading JTIDS's performance when signal-to-interference ratio (SIR) is small, whereas  pulsed-noise interference for a smaller fraction of time that the interference is on causes  the greatest degradation when SIR is large, whether the channel is fading or not.  In addition, two modified JTIDS/Link-16-compatible systems are proposed and  evaluated. The first system uses errors-and-erasures decoding (EED) in place of errorsonly  RS decoding, and the second system employs a new 32-chip CCSK sequence  instead of the 32-chip CCSK sequence chosen for JTIDS. For the first modified system,  the results show that EED outperforms errors-only RS decoding in all cases, whether  channel is fading or not. With EED, the most significant improvement is found when  both the fraction of time the interference is on is small and the signal-to-AWGN ratio is  large. For the second modified system, the new 32-chip CCSK sequence, obtained from a  search algorithm, allows for seven instead of six chip errors in the received sequence  without making a symbol error, but the results show that the probability of symbol error  obtained with the new CCSK sequence is only slightly better than that obtained with the  sequence chosen for JTIDS.
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<br>Subjects: AWGN; CCSK; EED; JTIDS; Link-16; MSK; Nakagami fading; narrowband interference; probability of symbol error; Reed-Solomon codes</div>
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Kao, Chi-Han</div>
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