Cooperative amplify-and-forward beamforming for OFDM systems with multiple relays
Liang YW, Schober R (2009)
Publication Type: Conference contribution
Publication year: 2009
Journal
Conference Proceedings Title: IEEE International Conference on Communications
Event location: Dresden
ISBN: 9781424434350
Abstract
In this paper, we propose frequency-domain (FD) and time-domain (TD) beamforming (BF) schemes for cooperative orthogonal frequency division multiplexing (OFDM) networks with multiple amplify-and-forward relays. Whereas for FD-BF the BF weights are applied in the FD, for TD-BF cyclic BF filters (C-BFFs) are used on the TD signal avoiding discrete-time Fourier transform operations at the relays and drastically reducing the required amount of feedback from the receiver to the relays. Adopting the average mutual information (AMI) per sub-carrier as optimality criterion, we show that the direction of the optimal FD-BF weights can be obtained in closed-form and that the optimal sub-carrier power allocation (PA) problem is convex. For solution of the PA problem an interior point method and a bisectional search dual method are provide. Furthermore, for solution of the C-BFF optimization problem an efficient gradient algorithm is proposed. Simulation results for IEEE 802.11n channels show that TD-BF with short C-BFFs closely approaches the performance of FD-BF and outperforms direct transmission without relaying. ©2009 IEEE.
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APA:
Liang, Y.W., & Schober, R. (2009). Cooperative amplify-and-forward beamforming for OFDM systems with multiple relays. In IEEE International Conference on Communications. Dresden.
MLA:
Liang, Yang Wen, and Robert Schober. "Cooperative amplify-and-forward beamforming for OFDM systems with multiple relays." Proceedings of the 2009 IEEE International Conference on Communications, ICC 2009, Dresden 2009.
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