We consider the design of cooperation coding schemes for a two-user multiaccess;channel (MAC). In particular, we consider two block Markov coding schemes, namely, the multiplexedcoding and the superposition coding. A...
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We consider the design of cooperation coding schemes for a two-user multiaccess;channel (MAC). In particular, we consider two block Markov coding schemes, namely, the multiplexedcoding and the superposition coding. Although the fully multiplexed (IMP) coding outperforms the superposition coding in theory, it is difficult to implement with practical error-correction codes. We, therefore, introduce a partiallymultiplexed (PMP) coding scheme for code rate R < 0.5, and propose a simplified superposition coding scheme. The outage analysis shows that these cooperation schemes provide significant gains over the noncooperative MAC in the low-power regime when the bandwidth W --> infinity. We then propose a PMP code design using irregular repeat accumulate (IRA) codes. The design method can be extended to build the low-rate PMP codes using irregular repeat zigzag Hadamard (IRZH) codes, a new class of capacity achieving low-rate codes. Simulation results demonstrate that the block Markov multiplexedcoding using PMP-IRA codes outperforms the practical superposition coding by 2 dB at 10(-2) FER, and it provides a 10-dB;gain over the noncooperative MAC. The multiplex coding using PMP-IRZH codes offers 1-dB gain over the superposition coding, and a 9.5-dB gain over noncooperative MAC at 10(-2) FER. Moreover, the PMP-IRZH coding performs only 0.5 dB away from the outage capacity of multiplexedcoding in the low-power regime.
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