References:
[1] Roy Yates and Narayan Mandayam, "Challenges
in Low-Cost Wireless Data Transmission," IEEE Signal Processing
Magazine, 17(3) 93-102, May 2000.
[2]
R.H. Frenkiel, B.R. Badrinath, J. Borras and R. Yates, "The Infostations
Challenge: Balancing Cost and Ubiquity in Delivering Wireless Data,"
IEEE Personal Communications, 7(2):
66-71, April 2000.
[3] A. Domazetovic, L.J. Greenstein, N.B. Mandayam, I. Seskar,
"Propagation Models for Short Range Wireless Channels with Predictable
Path Geometries", Submitted to IEEE Transactions on Communications,
2002.
[4] A. Domazetovic, L.J. Greenstein, N.B. Mandayam, I. Seskar,
"Estimating the Doppler Spectrum of a Short Range Fixed Wireless
Channel", IEEE Communications Letters, vol. 7, no. 2, pp.
227-229, May 2003.
[5] A. Domazetovic, L.J. Greenstein, N.B. Mandayam, I. Seskar, "A new
Modelling Approach for Wireless Channels with Predictable Path
Geometries", in IEEE VTC'02 Fall, September 2002, Vancouver,
Canada.
[6] S. Patel, "Comparative Evaluation of OFDM and Single-Carrier
Equalization for Infostation Channels", M.S. Thesis, ECE Dept.,
Rutgers University.
[7] W.H. Yuen, R.D. Yates, S.C. Mau, "Non Cooperative Content
Distribution in Mobile Infostation Networks", Proc. IEEE WCNC 2003.
[8] W.H. Yuen, R.D. Yates, S.C. Mau, "Exploiting Data and
Multiuser Diversity in Content Distribution for Mobile Infostation
Networks", Proc. IEEE INFOCOM 2003. 
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This
project seeks to develop an understanding of fundamental and practical
limits on the achievable data rates of short range radio systems.
Communication theory and simple link budget calculations tell us that
it is possible to build systems of Infostations in which small, separated
coverage areas facilitate transfer rates approaching a 1 Gb/s for
a fraction of the cost associated with conventional ubiquitous coverage.
However, the signal processing challenges are numerous and distinct
from the historical challenges offered by connection-oriented wireless
services. When a mobile user passes an Infostation, there will be
a window of opportunity, perhaps as short as a fraction of a second,
in which the user will have access to a high-rate communication channel.
A key task is to identify that window and transmit at an appropriate
rate. The mobile must make these decisions based on measurements of
a wideband radio channel in which there is frequency selectivity and
time variation in the fading as well as in the interference.
Technology Rationale:
Second and third generation wireless systems have been designed primarily
for voice, so they are connection oriented, delay sensitive, and provide
fixed bit rates. Additionally, since service is desired “anytime/anywhere,”
these systems must provide ubiquitous coverage. This coverage is achieved
through relatively uniform grids of cell sites, which are placed to
control interference and minimize outage rather than to maximize throughout.
As a result, such systems deliver low bit rates and are relatively
expensive when used for large amounts of information. At the same
time, wireline connection to the Internet has encouraged uses (and
users) that depend upon bits being virtually “free.” We contend that
this “economic” mismatch between wired and wireless access is the
primary obstacle to the dramatic growth of a wireless Internet.
Technical Approach:
In the specific context of an Infostations system, we have divided
our research into four components:
1. Radio Channel Modeling: The characterization
of typical Infostation radio channels.
2. Transceiver Design: The analysis
and performance evaluation of transmitters and receivers for both
single carrier and multicarrier systems.
3. Radio Resource Management:
Transmitter power and rate adaptation policies derived from receiver
measurements.
4. Algorithm Development Testbed: A platform employing DSP
and FPGA technology for the practical evaluation of transmitter and
receiver algorithms.
Results to Date:
Initial efforts focused on measurement and
modeling of the short-range radio channel followed by performance
evaluation for single-carrier and OFDM transceivers. We determined
that a 100 MHz channel will support data rates on the order of 500
Mb/s [3-6]. The radio channel modeling component of the project has
benefited from contributions and collaborations with Lucent
Technologies and AT&T Labs-Research. Positive results from radio
channel research has motivated new applications of short-range
radio. In particular, recent work on radio resource management has
emphasized the mobile infostations, i.e., peer to peer high
speed data exchange [7-8].
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Contact:
Professor Roy Yates
WINLAB Associate Director
732-445-5249
ryates@winlab.rutgers.edu
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