On the Performance of a Two-User MIMO Downlink System in Heavy Traffic

Author

Bhardwaj, Sumit ; Williams, Ruth J. ; Acampora, Anthony S.

Author_Institution

Dept. of Electr. & Comput. Eng., California Univ., San Diego, La Jolla, CA

Volume

53

Issue

5

fYear

2007

fDate

5/1/2007 12:00:00 AM

Firstpage

1851

Lastpage

1859

Abstract

A multiple-input multiple-output (MIMO) downlink system in which data is transmitted to two users over a common wireless channel is considered. The channel is assumed to be fixed for all transmissions over the period of interest and the ratio of anticipated average arrival rates for the two users, also known as the relative traffic rate, is the system design parameter. A packet-based traffic model is considered where data for each user is queued at the transmit end. A queueing analog for this system leads to a coupled queueing system for which a simple policy is known to be throughput-optimal under Markovian assumptions. Since an exact expression for the performance is not available, as a measure of performance (in heavy traffic), a diffusion approximation is established. This diffusion process is a two-dimensional (2-D) Semimartingale Reflecting Brownian Motion (SRBM) living in the positive quadrant of 2-D space

Keywords

Brownian motion; MIMO communication; Markov processes; queueing theory; telecommunication traffic; wireless channels; Markovian assumption; SRBM; heavy traffic; multiple-input multiple-output; packet-based traffic model; queueing system; semimartingale reflecting Brownian motion; two-user MIMO downlink system; wireless channel; Base stations; Brownian motion; Delay; Diffusion processes; Downlink; Information theory; MIMO; Throughput; Traffic control; Two dimensional displays; Coupled queueing systems; Semimartingale Reflecting Brownian Motion (SRBM); diffusion approximation; heavy traffic; multiple-input multiple-output (MIMO);

fLanguage

English

Journal_Title

Information Theory, IEEE Transactions on

Publisher

ieee

ISSN

0018-9448

Type

jour

DOI

10.1109/TIT.2007.894662

Filename

4167723