Design and Analysis of Multi-User SDMA Systems with Noisy Limited CSIT Feedback

TL;DR

This paper introduces a robust design for SDMA systems with noisy limited CSIT feedback, improving system goodput through novel precoding, user selection, and feedback strategies, with theoretical and simulation validation.

Contribution

It presents a low-complexity, asymptotically optimal feedback index assignment algorithm and a robust SDMA framework for noisy feedback environments.

Findings

Significant goodput gains over naive designs.

Goodput increases with feedback bits in interference-limited regime.

Goodput scales linearly with antennas and SNR in noise-limited regime.

Abstract

In this paper, we consider spatial-division multiple-access (SDMA) systems with one base station with multiple antennae and a number of single antenna mobiles under noisy limited CSIT feedback. We propose a robust noisy limited feedback design for SDMA systems. The solution consists of a real-time robust SDMA precoding, user selection and rate adaptation as well as an offline feedback index assignment algorithm. The index assignment problem is cast into a Traveling Sales Man problem (TSP). Based on the specific structure of the feedback constellation and the precoder, we derive a low complex but asymptotically optimal solution. Simulation results show that the proposed framework has significant goodput gain compared to the traditional naive designs under noisy limited feedback channel. Furthermore, we show that despite the noisy feedback channel, the average SDMA system goodput grows with the number of feedback bits in the interference limited regime while in noise limited regime increases linearly with the number of transmit antenna and the forward channel SNR.