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S. Schwarz, M. Rupp:
"Adaptive Channel Direction Quantization - Enabling Multi User MIMO Gains in Practice";
Talk: IEEE International Conference on Communications 2012 (ICC 2012), Ottawa, Canada; 06-10-2012 - 06-15-2012; in: "IEEE International Conference on Communications (ICC) 2012", (2012), 6947 - 6952.

Many candidate technologies for future wireless
communication systems (e.g., multi-user MIMO, interference
alignment), rely on accurate Channel State Information (CSI)
at the Transmitter (CSIT) to determine the appropriate multiantenna
pre-processing steps. Thus, in frequency division duplexing
systems, a dedicated feedback link has to be provided to each
attached user for CSI reporting. In order to keep the feedback
rate moderate, CSI quantization is required. Additionally, CSI is
typically only provided for a subset of all available time/frequency
resources, implicating the need for an interpolation algorithm at
the base station. Furthermore, to compensate for the processing
delay of the feedback link, CSI prediction is required as well.
In this work, we treat these problems by incorporating our
previously presented CSI feedback algorithm in a 3GPP LTEA
compliant wideband OFDM simulation environment, and
augmenting it with appropriate interpolators and predictors.
As an example, the performance of multi-user zero-forcing
beamfoming is investigated, under practical feedback delay- and
time-frequency granularity-constraints, demonstrating substantial
throughput gains, in case of low to moderate user mobility.