This paper addresses some of the opportunities and the challenges in the design of multi-hop systems that utilize cooperation with one or two intermediate regenerative relays to provide high-quality communication between a source and a destination. We discuss the limitations of using a distributed Alamouti scheme in the relay channel and the additional complexity required to overcome its loss of diversity. As an alternative to the distributed Alamouti scheme, we propose and analyze two Error Aware Distributed Space-Time (EADST) systems built around the Alamouti code. First, using a bit error rate based relay selection approach, we design an EADST system with one and two regenerative relays that rely on feedback from the destination and we show that the proposed system improves on the distributed Alamouti scheme. In addition, we prove that the proposed one relay EADST system collects the full diversity of the distributed MISO channel. Second, we introduce an EADST system without feedback in which the relaying energies depend on the error probabilities at the relays. Numerical results show that both EADST systems perform close to the error probability lower bound obtained by considering error-free reception at the relays.
Bibliographical noteFunding Information:
Manuscript received November 14, 2004; revised August 4, 2005 and April 4, 2006; accepted May 23, 2006. The associate editor coordinating the review of this paper and approving it for publication was T. Duman. P. Anghel and M. Kaveh are with the University of Minnesota, 200 Union St SE, Minneapolis, MN 55455 (email: email@example.com). G. Leus is with Faculty of Electrical Engineering, Delft University, Mekel-weg 4, Delft 2628 CD, The Netherlands (email: firstname.lastname@example.org). He is supported in part by the NWO-STW under the VIDI program (DTC.6577). Digital Object Identifier 10.1109/TWC.2006.04750.
- Cooperative systems
- Distributed space-time coding
- Regenerative relays