- Link:
- http://hdl.handle.net/1783.1/3579
- Collection:
-
- Subjects
- Wireless communication systems Resource allocation -- Mathematical models Telecommunication -- Traffic -- Mathematical models Telecommunication -- Traffic -- Mathematical
models
- Creator:
- Lo, Ernest Sze-Yuen
- Format
- 337 bytes
- Format
- text/html
- Language
- en_US
- Type
- Thesis
- Description
- Thesis (Ph.D.)--Hong Kong University of Science and
Technology, 2008
- Description
- xvii, 145 leaves : ill. ; 30 cm
- Description
- HKUST Call Number: Thesis ECED 2008
Lo
- Description
- The scarcity of bandwidth has always been the bane
of high-speed wireless transmissions whose demand has been
tremendously increasing over the years. In order to tackle this
challenge, either the current resources should be more efficiently
utilized, or new radio resources should be sought for. This thesis
is built upon these two philosophies and aims to provide new
insights and design principles for wireless multiuser transmissions
over the physical, link and medium-access control layers. Initial
efforts are put on the multiuser resource allocation problem over
the multiple-input-multiple-output (MIMO) channels using multiple
antennas. The downlink is of interest since most data loading of
many multimedia services goes there. Specifically, two emerging
multiplexing schemes, namely, orthogonal frequency division
multiple access (OFDMA) and multi-carrier code division multiple
access (MC-CDMA), are evaluated. Their capacity limit and
relationship with the number of antennas, fading channel condition,
fairness among users and delay concern are investigated and
compared through the proposed sum-rate-optimal joint power and
sub-channel allocation algorithms. The multi-cell scenario,
essentially an interference channel, is also studied. Then, new
radio resources are investigated and the rest of the thesis focuses
on a new paradigm of communications with user cooperation.
Conventional MIMO point-to-point transmission exploits efficiently
the spatial-domain resources, but it is never meant to be a
solution for small devices, nor does it represent the full picture
of the potential values in the wireless medium. User cooperation
further takes advantage of the broadcasting nature of wireless
transmissions and exploits the signal copies received by multiple
users. In this thesis, there are three main results corresponding
to the downlink, uplink and two-way cooperative communications. The
first one tackles a fundamental bottleneck of cooperative
transmissions for the downlink, the spectral loss due to splitting
a timeslot into two halves for half-duplex relaying. System
dynamics are exploited and resource allocation is investigated
under the proposed new cooperation framework. The second one
provides a new interpretation for coded cooperation in the uplink.
A generalized cooperative concatenated coding framework is
proposed. Unlike conventional schemes that focus only on
cooperative spatial diversity, a novel joint-user coding technique
is devised which can also enhance the code structure while
requiring only limited degree of cooperation. Other practical
issues such as erroneous inter-user channels and variable
cooperation group are also taken into consideration. The third one
studies the roles of binary and analog network coding on two-way
relay-assisted wireless communications with equal-rate
applications. The binary and analog versions are often associated
with a three-step and two-step frameworks, respectively. While
there is an increasing interest in the latter one, we demonstrate
that the three-step framework may actually offer more potential
benefits. A simple but efficient protocol is proposed which
outperforms the schemes in the literature, and the outage regions
of the schemes are theoretically characterized.
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