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<p>The Joint Tactical Information Distribution System (JTIDS)/Link-16 is a hybrid  frequency-hopped, direct sequence spread spectrum system which is used for the  exchange of real-time tactical data. The five-bit data symbols are encoded with a (31,15)  Reed-Solomon (RS) code and transmitted over the channel with cyclical code-shift  keying modulation. Although JTIDS/Link-16 has proven to be operationally useful, one  of its primary drawbacks is its limited data rate. This thesis focuses on performance  analyses of alternative waveforms that achieve better data rates and better performance in  terms of required signal power. Two alternative waveforms were considered in this  thesis. The first alternative JTIDS/Link-16 waveform uses (31,15) RS encoding just as  the original JTIDS/Link-16 waveform, but the five-bit symbol stream generated at the  output of the RS encoder undergoes serial-to-parallel conversion to two five-bit symbol  streams. Each five-bit symbol stream is then mapped into a six-bit symbol stream before  being independently transmitted on the in-phase (I) and quadrature (Q) components of the  carrier using complex 64-ary bi-orthogonal keying modulation (64-BOK). The second  alternative JTIDS/Link-16 waveform uses (63,47) RS encoding, where the six-bit symbol  stream generated at the output of the RS encoder undergoes serial-to-parallel conversion  to six-bit symbol streams which are then each independently transmitted on the I and Q  components of the carrier using complex 64-BOK modulation. The performance results  obtained for the two alternative JTIDS/Link-16 waveforms are compared to those  obtained for the existing JTIDS/Link-16 waveform for additive white Gaussian noise  (AWGN) as well as when both AWGN and pulse-noise interference (PNI) are present.  Errors-and-erasures decoding (EED) as well as errors-only decoding are also considered  for the two alternative waveforms. From the analyses, we see that the two proposed  alternative JTIDS/Link-16 waveforms perform better in the presence of AWGN as well  as both AWGN and PNI. There is no significant advantage when EED is used for either  of the two alternative waveforms considered. When perfect-side information  demodulation is used, the results show significant improvements in performance for the  two alternative waveforms when both AWGN and PNI are present.
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<br>Subjects:</div>
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Kee, Cheng Hoe</div>
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