Diversity-Multiplexing Tradeoff in Multiple Antenna Systems with Quantized Feedback

In this paper, we derive lower bounds on optimal diversity-multiplexing tradeoff in multiple antenna channels when the transmitter has finite bits of channel state information. We show that for each multiplexing gain, the diversity order is higher than the case without feedback. Furthermore, as the number of feedback bits increases, the diversity-multiplexing tradeoff grows unboundedly to approach the case of perfect channel state information at the transmitter. The major reason for diversity order gain is the opportunistic use of channel degrees of freedom, in the form of “location-dependent” temporal power control, which adapts the power control strategy based on the average signal to noise ratio of the channel. Index Terms Finite rate, quantized, feedback, diversity, multiplexing, MIMO