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Energy-efficient cooperative relaying over fading channels with simple relay selection

Madan, Ritesh and Mehta, Neelesh B and Molisch, Andreas F and Zhang, Jin (2008) Energy-efficient cooperative relaying over fading channels with simple relay selection. In: EEE GLOBECOM Technical Conference & IEEE COMMUNICATIONS EXPO, 27 November 2006, pp. 3013-3025.

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Abstract

We consider a cooperative wireless network where a set of nodes cooperate to relay in parallel the information from a source to a destination using a decode-and-forward approach. The source broadcasts the data to the relays, some or all of which cooperatively beamform to forward the data to the destination. We generalize the standard approaches for cooperative communications in two key respects: (i) we explicitly model and factor in the cost of acquiring channel state information (CSI), and (ii) we consider more general selection rules for the relays and compute the optimal one among them. In particular, we consider simple relay selection and outage criteria that exploit the inherent diversity of relay networks and satisfy a mandated outage constraint. These criteria include as special cases several relay selection criteria proposed in the literature. We obtain expressions for the total energy consumption for general relay selection and outage criteria for the non-homogeneous case, in which different relay links have different mean channel power gains, and the homogeneous case, in which the relay links statistics are identical. We characterize the structure of the optimal transmission scheme. Numerical results show that the cost of training and feedback of CSI is significant. The optimal strategy is to use a varying subset (and number) of relay nodes to cooperatively beamform at any given time. Depending on the relative location of the relays, the source, and the destination, numerical computations show energy savings of about 16% when an optimal relay selection rule is used. We also study the impact of shadowing correlation on the energy consumption for a cooperative relay network.

Item Type: Conference Paper
Additional Information: Copyright for this article belongs to Mitsubishi Electric Research Laboratories
Keywords: cooperative networks; relay networks; Rayleigh fading; broadcast; beamform; channel state information; energy optimization; outage; virtual branch analysis; optimization
Department/Centre: Division of Biological Sciences > Molecular Reproduction, Development & Genetics (formed by the merger of DBGL and CRBME)
Date Deposited: 31 Dec 2008 07:20
Last Modified: 19 Sep 2010 04:51
URI: http://eprints.iisc.ernet.in/id/eprint/16366

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