Subject: [NEXTEL-1] Lucent Technologies- Throughput Simulations for MIMO and transmit diversity

From: [email-masked]
Date: Tue, 17 Feb 2004 14:27:36 -0500

Agenda item:
Source: Lucent Technologies
Title: Throughput Simulations for MIMO and transmit diversity
enhancements to HSDPA
Document for: Discussion

1. INTRODUCTION

A work item on High Speed Downlink Packet Access (HSDPA) was proposed by
Motorola in [1]. MIMO transmission was proposed by Lucent to enhance the
performance of HSDPA [2].  Link level simulations results were presented showing
potential gains for different coding and modulation schemes achieving data rates
of up to 21.6 Mbps [3]. While the link simulations showed significant gains
mostly for the higher data rates the impact of the MIMO technology at the system
level in terms of metrics such as the average system throughput is of interest.
This is especially the case since most of the link gains shown in [3] were for
the high data rates which will typically only be feasible for terminals
relatively close to the base station. In this contribution, we present average
sector throughput results as a function of the number of base and terminal
antennas available. Previous contributions on system simulation methodology do
not address how system simulations can be performed when multiple antennas are
considered. We describe here how the simulation methodology of [4] for single
antenna set up can be generalized to multiple antennas and thus can be adopted
for system throughput simulations for MIMO and diversity transmission
techniques. Because many high speed applications for the HSDPA are more tolerant
to packet delays than voice applications, a judicious scheduling algorithm can
improve the system performance significantly. We evaluate the throughput as a
function of the number of users for three different scheduling algorithms,
namely max carrier-to-interference (C/I) [4], round robin and proportional fair
scheduling. We illustrate through the simulation results, the interaction of
transmit diversity and multi-user diversity from scheduling for the different
scheduling algorithms.  The details of the simulation assumptions are presented
in the next section. We emphasize that the simulation results reported here do
make several simplifying assumptions. All packets are assumed to be single slot
transmissions and hybrid ARQ is not considered. Error in C/I estimation at the
terminal or the feedback delay and errors in reporting the C/I are not included
in the simulations. Fast cell-site selection is limited to choosing the best
base station at the time the terminals are placed in the sector. Only single
path Rayleigh fading, independent across all antennas is considered.
Nevertheless, relative comparison of performance achieved by the different
antenna configurations would indicate potential gains from use of multiple
antennas.

More:

http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_17/Docs/PDFs/R1-00-1388.pdf

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