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Project Description
The objective of the proposed project is to develop a
protocol suite that would be adaptive to the different
aspects of heterogeneity exhibited by next generation
wireless systems. The comprehensive protocol suite would
include solutions at the application, transport, network,
and link layers.
With the mobile user populace expected to increase to an
incredible 1 billion users by the year 2005, wireless data
services are receiving hitherto unseen attention. In order to
provide data and multimedia services to such large numbers
of users, it is imperative that efficient solutions are
developed for next generation wireless systems. One key
problem that can plague the performance experienced
by wireless users is the unique heterogeneity that next
generation wireless systems are expected to exhibit in terms of
the network environment, network topology, and application
requirements. Currently, no solutions exist for comprehensively
addressing the whole gamut of heterogeneity. Leaving the
heterogeneity un-addressed will in turn lead to a gross
under-utilization of the already scarce wireless resources.
The adaptive protocol stack proposed would act as a
panacea for the ills caused by the varying dimensions of
heterogeneity, and hence would significantly enhance performance.
Consequently, the impact of the proposed project is
the facilitation of seamless connectivity, richer services, and
better quality for wireless data users. 4G (fourth generation)
wireless systems are expected to be deployed within a decade and
are still in the infancy of their design stages. We hope to channel
the results of our proposed research toward making significant
contributions to the 4G development effort. The timeline
of the proposed project would conveniently facilitate such a
contribution.
The technology and business of wireless communications systems
have made spectacular progress since the first systems were
introduced fifteen years ago. Currently proposed third generation
(3G) systems offer roaming, higher capacity, and increased
flexibility for low bandwidth services, such as voice calls and
messaging. While future wireless systems (fourth generation (4G)
and higher) are envisioned to provide higher capacity, they are
also expected to support heterogeneity in the following aspects:
(i) physical environments (ranging from high-bandwidth low
error-rate pico-cells to low-bandwidth high error-rate
macro-cells); (ii) network architectures (cellular, peer-to-peer,
or other hybrid network models); and (iii) applications (ranging
from low-data rate non-real-time applications to high-data rate
real-time applications). In this project, we will investigate
several key elements that are necessary to realize a protocol
stack for a mobile station in 4G wireless systems. The
ultimate objective is to develop an adaptive protocol suite that
would adapt itself to the different aspects of heterogeneity
exhibited by the next generation wireless systems. In particular
we will investigate the following problems:
- Application Layer
- Data-rate scalability
- Joint optimal real-time video streaming system
- Transport Layer
- Heterogeneous network characteristics
- Heterogeneous network architectures
- Network Layer
- Application requirements
- Heterogeneous network architectures
- Data Link Layer
- Rate-compatible error control coding
Application Layer
- Data-rate scalability: We introduce an optimal dynamic rate
shaping technique to be utilized in the case of congestion or bandwidth variations.
- Jointly optimal real-time video streaming system: We
propose a real-time video streaming system featuring an 3-D
SPIHT-based multiple stream coding, a practically efficient
unequal error protection mechanism, and an error-concealment
method.
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Transport Layer
- Heterogeneous Network Characteristics: We propose to build a
single transport protocol that will adapt itself to the
characteristics of a variety of wireless network environments.
- Heterogeneous Network Architectures: We propose to explore
transport layer adaptivity to the underlying network model
(cellular, peer-to-peer, or hybrid).
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Network Layer
- Application Requirements: We will explore network layer
constructs that enable heterogeneous applications to implement
custom network layer policies.
- Heterogeneous Network Architectures: We will explore the
use of novel state propagation schemes and virtual backbone
approaches to enhance transport layer performance and help in
adapting to heterogeneous network models.
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Data Link Layer
- Rate-compatible error control coding: We develop new types of
rate-compatible convolutional codes using finite-field wavelet
transforms.
The protocol suite requires a new Protocol Suite
Integration Plan. The project will consist of four phases.
During the first phase we will design the details of all the
proposed components/protocols/methods of the protocol suite.
During the second phase we will assess their performance in a
simulation testbed. During the third phase we will integrate the
individual modules into the suite and finally in the fourth phase
we will prototype the proposed protocol suite and we will assess
its performance on a physical testbed.
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