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arXiv · 0903.1502

Low-Density Graph Codes for slow fading Relay Channels

Dieter Duyck·Joseph J. Boutros·Marc Moeneclaey
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Abstract

We study Low-Density Parity-Check (LDPC) codes with iterative decoding on block-fading (BF) Relay Channels. We consider two users that employ coded cooperation, a variant of decode-and-forward with a smaller outage probability than the latter. An outage probability analysis for discrete constellations shows that full diversity can be achieved only when the coding rate does not exceed a maximum value that depends on the level of cooperation. We derive a new code structure by extending the previously published full-diversity root-LDPC code, designed for the BF point-to-point channel, to exhibit a rate-compatibility property which is necessary for coded cooperation. We estimate the asymptotic performance through a new density evolution analysis and the word error rate performance is determined for finite length codes. We show that our code construction exhibits near-outage limit performance for all block lengths and for a range of coding rates up to 0.5, which is the highest possible coding rate for two cooperating users.

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Dieter Duyck, Joseph J. Boutros, Marc Moeneclaey. 2011-03-28. Low-Density Graph Codes for slow fading Relay Channels. https://doi.org/10.1109/tit.2011.2145470

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