Sum rate analysis of a reduced feedback OFDMA system employing joint scheduling and diversity

TL;DR

This paper analyzes the sum rate performance of a reduced feedback OFDMA system with joint scheduling and diversity, providing closed-form expressions and feedback ratio guidelines for different multi-antenna schemes.

Contribution

It introduces a unified analytical framework for sum rate in reduced feedback OFDMA systems with joint scheduling and diversity, including closed-form results for multiple transmitter schemes.

Findings

Closed-form sum rate expressions for TAS, OSTBC, and CDD.

Approximate feedback ratio needed for full feedback sum rate performance.

Framework applicable to quantized and non-quantized CQI feedback schemes.

Abstract

We consider joint scheduling and diversity to enhance the benefits of multiuser diversity in an \OFDMA{} system. The \OFDMA{} spectrum is assumed to consist of $\Nrb$ resource blocks and the reduced feedback scheme consists of each user feeding back channel quality information (\CQI) for only the best-$\NFb$ resource blocks. Assuming largest normalized \CQI{} scheduling and a general value for $\NFb$, we develop a unified framework to analyze the sum rate of the system for both the quantized and non-quantized \CQI{} feedback schemes. Based on this framework, we provide closed-form expressions for the sum rate for three different multi-antenna transmitter schemes; Transmit antenna selection (\TAS), orthogonal space time block codes (\OSTBC) and cyclic delay diversity (\CDD). Furthermore, we approximate the sum rate expression and determine the feedback ratio $(\frac{\NFb}{\Nrb})$ required to achieve a sum rate comparable to the sum rate obtained by a full feedback scheme.