IEEE Transactions on Signal Processing
MMSE-based joint source and relay precoding design for amplify-and-forward MIMO relay networks
IEEE Transactions on Wireless Communications
A limited feedback joint precoding for amplify-and-forward relaying
IEEE Transactions on Signal Processing
IEEE Transactions on Signal Processing
Power allocation for beamforming relay networks under channel uncertainties
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Downlink distributed beamforming through relay networks
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
IEEE Transactions on Communications
A simple linear precoder for selection-type cooperative MIMO systems
IEEE Communications Letters
MMSE based transceiver designs in closed-loop non-regenerative MIMO relaying systems
IEEE Transactions on Wireless Communications
Performance analysis in AF/DF relay networks with beamforming
Asilomar'09 Proceedings of the 43rd Asilomar conference on Signals, systems and computers
Joint receive-transmit beamforming for multi-antenna relaying schemes
IEEE Transactions on Signal Processing
IEEE Transactions on Signal Processing
Multimode antenna selection for MIMO amplify-and-forward relay systems
IEEE Transactions on Signal Processing
Transceiver design for dual-hop nonregenerative MIMO-OFDM relay systems under channel uncertainties
IEEE Transactions on Signal Processing
Relay Selection Algorithm with Simplified Precoding for MIMO Multiple Relay Channels
Wireless Personal Communications: An International Journal
MIMO relay wireless networks with scheduling and transmit beamforming
Wireless Communications & Mobile Computing
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We consider the problem of beamforming codebook design for limited feedback half-duplex multiple-input multiple output (MIMO) amplify-and-forward (AF) relay system. In the first part of the paper, the direct link between the source and the destination is ignored. Assuming perfect channel state information (CSI), we show that the source and the relay should map their signals to the dominant right singular vectors of the source-relay and relay-destination channels. For the limited feedback scenario, we prove the appropriateness of Grassmannian codebooks as the source and relay beamforming codebooks based on the distributions of the optimal source and relay beamforming vectors. In the second part of the paper, the direct link is considered in the problem model. Assuming perfect CSI, we derive the optimization problem that identifies the optimal source beamforming vector and show that the solution to this problem is uniformly distributed on the unit sphere for independent and identically distributed (i.i.d) Rayleigh channels. For the limited feedback scenario, we justify the appropriateness of Grassmannian codebooks for quantizing the optimal source beamforming vector based on its distribution. Finally, a modified quantization scheme is presented, which introduces a negligible penalty in the system performance but significantly reduces the required number of feedback bits.