Turbo Packet Combining Strategies for the MIMO-ISI ARQ Channel
| Autor: | Ait-Idir, Tarik, Saoudi, Samir |
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| Rok vydání: | 2009 |
| Předmět: | |
| Zdroj: | IEEE Transactions on Communications, vol. 57, no. 12, pp. 3782-3793, Dec. 2009 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1109/TCOMM.2009.12.080318 |
| Popis: | This paper addresses the issue of efficient turbo packet combining techniques for coded transmission with a Chase-type automatic repeat request (ARQ) protocol operating over a multiple-input--multiple-output (MIMO) channel with intersymbol interference (ISI). First of all, we investigate the outage probability and the outage-based power loss of the MIMO-ISI ARQ channel when optimal maximum a posteriori (MAP) turbo packet combining is used at the receiver. We show that the ARQ delay (i.e., the maximum number of ARQ rounds) does not completely translate into a diversity gain. We then introduce two efficient turbo packet combining algorithms that are inspired by minimum mean square error (MMSE)-based turbo equalization techniques. Both schemes can be viewed as low-complexity versions of the optimal MAP turbo combiner. The first scheme is called signal-level turbo combining and performs packet combining and multiple transmission ISI cancellation jointly at the signal-level. The second scheme, called symbol-level turbo combining, allows ARQ rounds to be separately turbo equalized, while combining is performed at the filter output. We conduct a complexity analysis where we demonstrate that both algorithms have almost the same computational cost as the conventional log-likelihood ratio (LLR)-level combiner. Simulation results show that both proposed techniques outperform LLR-level combining, while for some representative MIMO configurations, signal-level combining has better ISI cancellation capability and achievable diversity order than that of symbol-level combining. Comment: 13 pages, 7 figures, and 2 tables |
| Databáze: | arXiv |
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