Impact of Limited Feedback on MIMO-OFDM Systems using Joint Beamforming

TL;DR

This paper investigates how limited feedback impacts MIMO-OFDM systems with joint beamforming, demonstrating that even minimal feedback can nearly match the performance of perfect channel knowledge.

Contribution

It introduces a simple channel quantization scheme using random vector quantization for limited feedback in MIMO-OFDM systems.

Findings

Performance approaches perfect channel knowledge with few feedback bits

Random vector quantization effectively quantizes channel information

Limited feedback significantly improves system robustness

Abstract

In multi input multi output antenna systems, beamforming is a technique for guarding against the negative effects of fading. However, this technique requires the transmitter to have perfect knowledge of the channel which is often not available a priori. A solution to overcome this problem is to design the beamforming vector using a limited number of feedback bits sent from the receiver to the transmitter. In the case of limited feedback, the beamforming vector is limited to lie in a codebook that is known to both the transmitter and receiver.When the feedback is strictly limited, important issues are how to quantize the information needed at the transmitter and how much improvement in associated performance can be obtained as a function of the amount of feedback available.In this paper channel quantization schema using simple approach to codebook design (random vector quantization)is illustrated. Performance results show that even with a few bits of feedback, performance can be close to that with perfect channel knowledge at the transmitter.