Satellite modem equipment using advanced coding and modulation techniques for current and potential INTELSAT services

Higher-order modulation schemes like 8PSK combined with powerful channel coding techniques like trellis coding and conjugateness Reed-Solomon coding, have been demonstrated in the INTELSAT study INTEL-1268 to achieve a higher bandwidth efficiency compared to QPSK with conventional coding. Almost error-free transmission (BER<10/sup -10/) is demonstrated with an engineering model, for E/sub b//N/sub o/>5 dB with QPSK modulation, rate-3/4 convolutional code conjugateness with RS code according to IESS-308 (IDR), and for E/sub b//N/sub o/>6 dB with 8PSK modulation, rate-2/3 trellis code conjugateness with a (255,235,10) RS code. The following efficiencies are obtained: QPSK: (rate 3/4 Viterbi plus RS coding). Efficiency=1.15 bit/s/Hz and 8-PSK: (rate 2/3 trellis plus RS coding). Efficiency=1.54 bit/s/Hz. The overall transmission delay for a typical 2 Mbps carrier is: QPSK: (rate 3/4 Viterbi plus RS coding). Delay=3 ms (@ 2.048 Mbps) and 8PSK: (rate 2/3 trellis plus RS coding). Delay=10 ms (@ 2.048 Mbps). The feasibility of fully software switchable and programmable QPSK/8PSK modem/codec equipment has been demonstrated. Price estimates for this switchable QPSK/8PSK modem/codec equipment show excellent price/performance ratios for this new type of equipment.<
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