by Peter M. Grant
Peter Grant is Professor of Electronic Signal Processing at the University of
Edinburgh, Scotland. He received an 1997 IEEE Distinguished Lecturer award.
Department of Electrical Engineering,
The University of Edinburgh,
Mayfield Road,
Edinburgh EH9 3JL, UK.
tel. +44/131 650 5569
fax. +44/131 650 6554
e-mail: P.M.Grant@ee.ed.ac.uk
Playlist leading you through Peter Grant's
talk on the topic of array processing and adaptive antennas for CDMA.
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- mp3 Introduction
- mp3 Array Processing
and Null Steering History
- mp3 Uplink and Downlink
- mp3 Channel modeling:
Multipath profiles, local and far-out reflectors
- mp3 Multipath leads
to fading
- mp3 Measured channel
data in Edinburgh
- mp3 Carrier wave components
may sum constructively or destructively
- mp3 ** / HTML
page: Power versus delay and angle
- mp3 / HTML
page: Measurement artifacts in delay-angle map
- mp3 Frequency responses
at 4 antennas at 4 time instants
- mp3 / HTML
page: Table of delay, angle and Doppler for various environments
- mp3 Summary of CDMA
system properties
- mp3 Diversity through
multipath resolution, coding and interleaving or antenna diversity
- mp3 Antenna arrays
provide diversity, which enhances system performance.
- mp3 Antenna arrays
with M antenna elements are easiest analyzed using a narrowband channel
model.
- mp3 Regular arrays
give particular beam patterns. Half wavelength spacing. Aliasing in the spatial
domain.
- mp3 Channel model
with a few fixed taps. Ring of scatterers.
- mp3 A smart antenna
does signal processing to amplify the wanted signal, based on its angle of
arrival.
- mp3 In CDMA, you
down-convert to baseband, then remove the spreading code. The processor then
does space (angle) and time (multipath delay) combining.
- mp3 User traffic
distributions affect the performance. Simulations assume that the channels
and locations are perfectly known.
- mp3 The receiver
exploits spatial redundancy to suppress interference. In CDMA, the number
of signals largely exceeds the number of antenna elements. Nulling of interference
is not feasible.
- mp3 Receive algorithms
(fixed beam, direction of arrival, multipath estimation, or interference suppression.)
- mp3 Results for 1
GHz, 8 elements, average over 50 symbols, fixed channel, no Doppler. Fixed
beams work well with angles of arrival differing by 20 degrees. Sophisticated
processing can handle practically any angle distributions. With fast motion,
i.e., 200 Hz Doppler, errors in channel estimation cause loss in performance.
- mp3 Capacity depends
on mobile range, which is a measure of angular width. Discussion of capacity
curves.
- mp3 Antenna arrays
are simple and provide significant gains. Summary of comparison of algorithms.
- mp3 Third generation
systems need to support three basic services.
- mp3 Credits.
- mp3 Response to question:
"Is matrix inversion needed?"
Further Reading
- HTML Text
- Slides from the "1997 Distinguished Lecturer" presentation in PDF
- Additional slides in PDF/PS
- CDMA Array Processing paper in PDF/PS/HTML
