Near-optimal downlink precoding for two-tier priority-based wireless networks
KAUST DepartmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Electrical Engineering Program
Communication Theory Lab
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AbstractIn this paper, we study a two-tier priority-based wireless cellular network in which the primary base station (BS) has multiple antennas and the other terminals have a single antenna. We assume that we have two classes of users: high priority users and low priority users. We consider a rate maximization problem of the low priority users under signal-to-interference-plus-noise-ratio constraints on the high priority user to guarantee a certain quality-of-service for the high priority user. Since the interference due to the low priority users which communicate with each other via direct transmission may severely degrade the performance of the high priority user, we propose a BS-aided two-way relaying approach in which the BS helps relay the low priority users' signals instead of allowing them to communicate with each other via a direct path between them. In addition, an algorithm to find a near-optimal beamforming solution at the BS is proposed. The asymptotic results in the high power regime are derived to verify the average sum rate performance in the proposed scheme. Finally, based on some selected numerical results, we show that the proposed scheme outperforms the direct transmission scheme over a wide transmit power range.
SponsorsManuscript received February 11, 2014; revised June 2, 2014; accepted August 30, 2014. Date of publication September 8, 2014; date of current version February 6, 2015. This work was supported in part by a SABIC postdoctoral fellowship and the work of M.-S. Alouini was supported by the Qatar National Research Fund (a member of Qatar Foundation) under NPRP Grant NPRP 5-250-2-087. The statements made herein are solely the responsibility of the authors. The associate editor coordinating the review of this paper and approving it for publication was G. T. F. de Abreu.