A new beamforming for 60GHz wireless system with reduced feedback overhead
ISCIT'09 Proceedings of the 9th international conference on Communications and information technologies
Simplified maximum-likelihood precoder selection for limited feedback spatial multiplexing systems
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Link adaptation in linearly precoded closed-loop MIMO-OFDM systems with linear receivers
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Limited-rate channel state feedback for multicarrier block fading channels
IEEE Transactions on Information Theory
Efficient QR-Based Multi-Mode Precoding for Limited Feedback Multi-User MIMO Systems
Wireless Personal Communications: An International Journal
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Spatial multiplexing with multi-mode precoding provides a means to achieve both high capacity and high reliability in multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. Multi-mode precoding uses linear transmit precoding that adapts the number of spatial multiplexing data streams or modes, according to the transmit channel state information (CSI). As such, it typically requires complete knowledge of the multi-mode precoding matrices for each subcarrier at the transmitter. In practical scenarios where the CSI is acquired at the receiver and fed back to the transmitter through a low-rate feedback link, this requirement may entail a prohibitive feedback overhead. In this paper, we propose to reduce the feedback requirement by combining codebook-based precoder quantization, to efficiently quantize and represent the optimal precoder on each subcarrier, and multi-mode precoder frequency down-sampling and interpolation, to efficiently reconstruct the precoding matrices on all subcarriers based on the feedback of the indexes of the quantized precoders only on a fraction of the subcarriers. To enable this efficient interpolation-based quantized multimode precoding solution, we introduce (1) a novel precoder codebook design that lends itself to precoder interpolation, across subcarriers, followed by mode selection, (2) a new precoder interpolator and, finally, (3) a clustered mode selection approach that significantly reduces the feedback overhead related to the mode information on each subcarrier. Monte-Carlo bit-error rate (BER) performance simulations demonstrate the effectiveness of the proposed quantized multi-mode precoding solution, at reasonable feedback overhead