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|Title: ||Cross-Layer Design for Cooperative Communications and Networking|
|Authors: ||Sadek, Ahmed Kamel|
|Advisors: ||Liu, K. J. Ray|
|Department/Program: ||Electrical Engineering|
|Sponsors: ||Digital Repository at the University of Maryland|
University of Maryland (College Park, Md.)
|Keywords: ||Engineering, Electronics and Electrical (0544)|
|Issue Date: ||10-Apr-2007|
|Abstract: ||Cooperative communications is a new communication paradigm in which different terminals in the wireless network share their
antennas and resources for distributed transmission and processing.
Recent studies have shown that cooperative communications can yield
significant performance improvement due to spatial diversity gains.
The theory of cooperative communications is however still immature
to fully understand its broader impacts on the design of future
This thesis contributes to the advancement of cooperative communications by developing and analyzing cooperation protocols at different
network levels, with the
goal to provide significant improvements in signal reliability,
coverage area, network throughput, and energy efficiency with
respect to other existing alternatives.
We first propose a family of cooperative protocols for multi-node
cooperative communications. We demonstrate that full diversity gains
is achieved, which yields a significant improvement in the error
performance. Based on the derived symbol-error-rate expressions, we
characterize the optimal power allocation strategy among the relays
and the source to further improve the performance of the system.
We develop distributed relay assignment protocols, and analyze their
outage performance. We derive lower bounds on any relay-assignment
scheme to benchmark the performance of our proposed schemes. We
study the impact of our proposed protocols on increasing the
coverage area of cellular networks without increasing the transmit
power or adding extra base-stations.
We demonstrate that the gains promised by cooperation can be
leveraged to the multiple-access layer. We propose the deployment of
cognitive relays to utilize the periods of silence of the terminals
to enable cooperation. This alleviates the spectral inefficiency
problems inherent in conventional cooperation protocols. Our results
reveal significant improvements in the maximum stable throughput
region and delay performance of the network.
Finally, an analytical framework for studying the energy efficiency
of cooperation in wireless networks is presented. This framework
considers the overhead in the processing and receiving powers
introduced by cooperation. The results characterize the regions
where cooperation is more energy efficient than direct transmission.
The results also provide guidelines for the design of power
allocation strategies, relay-assignment algorithms and the selection
of the optimal number of relays to help the source.|
|Appears in Collections:||UMD Theses and Dissertations|
Electrical & Computer Engineering Theses and Dissertations
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