Transmission Schemes based on Sum Rate Analysis in Distributed Antenna Systems

TL;DR

This paper derives an ergodic sum rate expression for distributed antenna systems and proposes a mode selection scheme that maximizes sum rate using distance information, reducing complexity while maintaining performance.

Contribution

It introduces a novel transmission scheme based on sum rate analysis that does not require channel state information at the transmitter, optimizing antenna-user pairings.

Findings

The proposed scheme achieves sum rates comparable to ideal mode selection.

The scheme significantly reduces the number of mode candidates needed.

Simulation results validate the accuracy of the sum rate expressions.

Abstract

In this paper, we study single cell multi-user downlink distributed antenna systems (DAS) where antenna ports are geographically separated in a cell. First, we derive an expression of the ergodic sum rate for the DAS in the presence of pathloss. Then, we propose a transmission selection scheme based on the derived expressions which does not require channel state information at the transmitter. Utilizing the knowledge of distance information from a user to each distributed antenna (DA) port, we consider the optimization of pairings of DA ports and users to maximize the system performance. Based on the ergodic sum rate expressions, the proposed scheme chooses the best mode maximizing the ergodic sum rate among mode candidates. In our proposed scheme, the number of mode candidates are greatly reduced compared to that of ideal mode selection. In addition, we analyze the signal to noise ratio cross-over point for different modes using the sum rate expressions. Through Monte Carlo simulations, we show the accuracy of our derivations for the ergodic sum rate. Moreover, simulation results with the pathloss modeling confirm that the proposed scheme produces the average sum rate identical to the ideal mode selection with significantly reduced candidates.