Multiple-frame precoding and multi-D mapping for BICM over ergodic NAF relay channels

作者：Rodriguez Leonardo Jimenez^*; Tran Nghi H; Le Ngoc Tho

来源：Wireless Communications and Mobile Computing, 2011, 11(12): 1564-1575.

DOI：10.1002/wcm.1242

• amplify-and-forward
• precoder
• capacity-approaching
• multi-dimensional mapping

This paper proposes the idea of precoding over multiple cooperative frames with multi-dimensional (multi-D) mapping for a bit interleaved coded modulation system over an ergodic non-orthogonal amplify-and-forward (NAF) half-duplex single-relay channel. The benefits of multiple-frame precoding and multi-D labeling are analyzed in two different regions: the error-floor region to exploit diversity and the turbo pinch-off region for near-capacity performance. In the error-floor area, it is shown that the diversity gain function of the considered system is (N(f) . d(H))th power of that of uncoded cooperative systems, where N(f) is the number of precoded cooperative frames and d(H) is the minimum Hamming distance of the outer code. To optimize the asymptotic coding gain, it is then shown that the source and relay must transmit orthogonally for best asymptotic performance. In the turbo pinch-off region, we demonstrate that the proposed system concatenated with a simple outer binary code can be employed to achieve near-capacity performance. Using union bounding techniques, we show that the optimal multi-D labeling for NAF relaying shall maximize the average Euclidean distance between all pairs in the multi-D rotated constellation whose labels differ in only 1 bit. The extrinsic information transfer charts are then used to match the outer code, the multi-D mapping, and the precoder. It is demonstrated that the proposed system is also promising for NAF relaying in the turbo pinch-off region, in the sense that it can operate below the achievable rate achieved by a conventional coded modulation scheme.

• 出版日期2011-12