Conference Paper

An Optimized User Selection Method for Cooperative Diversity Systems.

Dept. of Electr. & Comput. Eng., Aristotle Univ. of Thessaloniki, Thessaloniki
DOI: 10.1109/GLOCOM.2006.853 Conference: Proceedings of the Global Telecommunications Conference, 2006. GLOBECOM '06, San Francisco, CA, USA, 27 November - 1 December 2006
Source: IEEE Xplore

ABSTRACT Multi-user cooperative diversity is a recent techni- que promising great improvement of the performance of wireless communication systems operating in fading environments. Based on combinatorial optimization theory and specifically on the so-called knapsack problem, this paper presents a method of optimizing the selection among the potential cooperating users, when amplify-and-forward relays are used. In particular, two optimization problems are studied: the error probability mini- mization subject to total energy consumption constraints, and the dual one, the energy consumption minimization under error performance constraints. Depending on the frequency of repea- ting this selection, the above problems are categorized into short- term and long-term node selection. Numerical examples verify the expected knapsack scheme's advantage of adapting the number of cooperating users, depending on the desired performance- consumption tradeoff. Moreover, long-term node selection seems to lead to similar error or consumption performance compared to the short-term one, despite its simplicity. I. INTRODUCTION In the last few years, a new concept that is being acti- vely studied in multihop-augmented networks is multi-user cooperative diversity, where several terminals form a kind of coalition to assist each other with the transmission of their messages. In general, cooperative relaying systems have a source node multicasting a message to a number of cooperative relays, which in turn resend a processed version to the intended destination node. The destination node combines the signal received from the relays, taking into account the source's original signal (1)- (4).

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