http://ieeexplore.ieee.org TOC Alert for Publication# 49 2009 June 19 27 5 c1 c1 72 27 5 c2 c2 67 27 5 577 581 449 27 5 582 592 2125 27 5 593 605 596 27 5 606 621 668 27 5 622 634 1179 27 5 635 646 1330 27 5 647 661 451 27 5 662 672 874 27 5 673 684 556 27 5 685 698 606 27 5 699 712 624 27 5 713 728 874 27 5 729 737 569 27 5 738 748 519 27 5 749 762 825 27 5 763 772 639 27 5 773 787 2242 3 = X₁+ X₂+W₃, to the network-coded combination of the source packets, S₁ ⊕ S₂. This is in contrast to the traditional multiple-access problem, in which the goal is to obtain both S₁ and S₂ explicitly at the relay node. Trying to obtain S₁ and S₂ explicitly is an overkill if we are only interested in S1⊕S₂. In this paper, we refer to the transformation Y₃ → S₁ ⊕ S₂ as the Channel-decoding- Network-Coding process (CNC) in that it involves both channel decoding and network coding operations. This paper shows that if we adopt the Repeat Accumulate (RA) channel code at the two end nodes, then there is a compatible decoder at the relay that can perform the transformation Y₃ → S₁⊕S₂ efficiently. Specifically, we redesign the belief propagation decoding algorithm of the RA code for traditional point-to-point channel to suit the need of the PNC multiple-access channel. Simulation results show that our new scheme outperforms the previously proposed schemes significantly in terms of BER without added complexity.]]> 27 5 788 796 396 27 5 797 813 1655 27 5 814 824 489 27 5 c3 c3 64 27 5 c4 c4 56