Abstract
Cooperative communication systems using various relay strategies can achieve spatial diversity gains, enhance coverage, and potentially increase capacity. For the practically attractive decode-and-forward (DF) relay strategy, we derive a high-performance low-complexity coherent demodulator at the destination in the form of a weighted combiner. The weights are selected adaptively to account for the quality of both source-relaydestination and source-destination links. Analysis proves that the novel coherent demodulator can achieve the maximum possible diversity, regardless of the underlying constellation. Its error performance tightly bounds that of maximum-likelihood (ML) demodulation, which provably quantifies the diversity gain of ML detection with DF relaying. Simulations corroborate the analysis and compare the performance of the novel decoder with existing diversity-achieving strategies including analog amplify-andforward and selective-relaying.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1427-1438 |
| Number of pages | 12 |
| Journal | IEEE Transactions on Communications |
| Volume | 55 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jul 2007 |
Bibliographical note
Funding Information:Paper approved by S. N. Batalama, the Editor for Spread Spectrum and Estimation of the IEEE Communications Society. Manuscript received August 5, 2005; revised March 12, 2006 and August 3, 2006. This work was supported in part by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011, in part by the Spanish government under Grant TEC2005-06766-C03-01/TCM, and in part by the NSF Grant ECS03-29766. This paper was presented in part at the 39th Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, November 2005.
Keywords
- Decode-and-forward (DF)
- Diversity gain
- Full diversity
- Relay channel
- Relaying protocol
- User cooperation