Quantization and Bit Allocation for Channel State Feedback for Relay-Assisted Wireless Networks

TL;DR

This paper proposes a method for quantizing channel state information and allocating feedback bits in relay-assisted wireless networks to maximize sum rate performance under limited feedback constraints.

Contribution

It introduces a new quantization scheme and bit allocation algorithm optimized for minimizing rate loss in cooperative cellular networks with limited CSI feedback.

Findings

Derived tight bounds on rate differences due to quantization.

Developed an effective quantizer for arbitrary channel distributions.

Optimized bit allocation prioritizing links that most impact sum rate.

Abstract

This paper investigates quantization of channel state information (CSI) and bit allocation across wireless links in a multi-source, single-relay cooperative cellular network. Our goal is to minimize the loss in performance, measured as the achievable sum rate, due to limited-rate quantization of CSI. We develop both a channel quantization scheme and allocation of limited feedback bits to the various wireless links. We assume that the quantized CSI is reported to a central node responsible for optimal resource allocation. We first derive tight lower and upper bounds on the difference in rates between the perfect CSI and quantized CSI scenarios. These bounds are then used to derive an effective quantizer for arbitrary channel distributions. Next, we use these bounds to optimize the allocation of bits across the links subject to a budget on total available quantization bits. In particular, we show that the optimal bit allocation algorithm allocates more bits to those links in the network that contribute the most to the sum-rate. Finally, the paper investigates the choice of the central node; we show that this choice plays a significant role in CSI bits required to achieve a target performance level.