  Next generation wireless communications rely on multiple input multiple
output (MIMO) techniques to achieve high data rates. Feedback of channel
information can be used in MIMO precoding to fully activate the strongest
channel modes and improve MIMO performance. Unfortunately, the bandwidth of the
control channel via which the feedback is conveyed is severely limited. An
important issue is how to improve the MIMO precoding performance with minimal
feedback. In this letter, we present a method that uses a rotating codebook
technique to effectively improve the precoding performance without the need of
increasing feedback overhead. The basic idea of the rotating codebook precoding
is to expend the effective precoding codebook size via rotating multiple
codebooks so that the number of feedback bits remains unchanged. Simulation
results are presented to show the performance gain of the proposed rotating
codebook precoding over the conventional precoding.
