Robust Linear Beamformer Designs for Coordinated Multi-Point AF Relaying in Downlink Multi-Cell Networks

• Published in: IEEE transactions on wireless communications Vol. 11; no. 9; pp. 3272 - 3283
• Main Authors: KUO, Chun-I, WU, Sau-Hsuan, TSENG, Chun-Kai
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2012; Institute of Electrical and Electronics Engineers
• Subjects: Access methods and protocols, osi model; AF relaying; Applied sciences; CoMP; Complexity theory; Detection, estimation, filtering, equalization, prediction; Downlink; downlink multi-cell networks; Equipments and installations; Exact sciences and technology; Information, signal and communications theory; Interference; Mobile radiocommunication systems; network MIMO; Radiocommunications; Robust beamforming; Robustness; Signal and communications theory; Signal to noise ratio; Signal, noise; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Transmission and modulation (techniques and equipments); Uncertainty; Vectors; Relaying; Parameter estimation; Relay; Wireless telecommunication; Information rate; Feedback regulation; Data transmission; Downlink; Cell network; Beam forming; Optimization; CoMP; downlink multi-cell networks; Channel estimation; Electric power consumption; Routing protocols; Mobile radiocommunication; MIMO system; Estimation error; Quantization error; AF relaying; Transmission protocol; Robust beamforming; Information transmission; Simulation; Signal processing; Feasibility; Signal to interference plus noise ratio; network MIMO; Automatic repeat request
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2012.072512.111764

Robust beamforming methods are studied to support relay-assisted coordinated multi-point (CoMP) retransmissions in downlink multi-cell networks. Linear beamformers (BFers) for relay stations of different cells are jointly designed to maintain, in a CoMP amplify-and-forward (AF) relaying manner, the target signal to interference-plus-noise ratios (SINR) at the cellular boundaries of this type of networks. Considering the feasibility in realizations and deployments, BFer designs are only allowed to use the channel state information (CSI) feedbacks of the wireless links inside a network. This kind of designs turns out to be a challenging optimization problem when attempting to maintain the SINR under the estimation and quantization errors in CSI. A conservative criterion and solution method is proposed for this robust design problem. Despite the conservativeness, the proposed method appears to provide an effective BFer design for CoMP AF relaying, either from the perspective of power consumption or from the viewpoints of BFers' complexity and feasibility in syntheses. Simulations also show that when applying the proposed CoMP AF relaying method in Automatic Retransmission reQuest (ARQ), data throughput can be efficiently increased for users close to the joint cellular boundaries inside a multi-cell network.