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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. On the structure of the multiuser QOS region
 IEEE transactions on signal processing 55 (2007), No.7, pp.34843495 ISSN: 00963518 ISSN: 00189278 ISSN: 00961620 ISSN: 1053587X 

 English 
 Journal Article 
 Fraunhofer HHI () 
Abstract
The qualityofservice (QoS) feasible region (the set of jointly feasible QoS) of a multiuser system is limited by mutual interference. In this paper, we characterize the region under the assumption that the interference coupling between the users can be described by a parameterdependent matrix, where the parameter stands for some receive (or transmit) strategy. This model holds for a large class of practically relevant system designs (e.g., beamforming, CDMA). In general, interference coupling is strongly influenced by the receive strategy. Thus, classical results based on the assumption of fixed irreducible coupling matrices cannot be transferred directly. New techniques are required to describe systems, where users are partially decoupled because of the impact of the receive strategy. We develop an analytical framework, which considers the close interaction between receive strategy and power allocation, but without the restricting assumption of irreducibility. We characterize the structure of the boundary, and explain the system behavior in the high signaltonoise ratio (SNR) regime. We provide conditions for existence and uniqueness of an optimal power allocation, given an optimal choice of receive strategy. We also discuss the duality between interference mitigation at the receiver and at the transmitter. Finally, we propose a globally convergent algorithm, which computes the minmax optimal power allocation under the assumption of blockirreducibility (independent irreducible subsystems).