- Link:
- http://hdl.handle.net/1783.1/3587
- Collection:
-
- Subjects
- Wireless communication systems -- Quality control Resource allocation -- Data processing Wireless communication systems -- Quality
control
- Creator:
- Weng, Lingfan
- Format
- 341 bytes
- Format
- text/html
- Language
- en_US
- Type
- Thesis
- Description
- Thesis (Ph.D.)--Hong Kong University of Science and
Technology, 2008
- Description
- xii, 104 leaves : ill. ; 30 cm
- Description
- HKUST Call Number: Thesis ECED 2008
Weng
- Description
- Next generation wireless communication systems need
to support data rates much greater than in 3G systems. This will
require more efficient utilization of the radio resource by using
new and techniques such as cooperative wireless networks. This
thesis focuses on the analysis and allocation of radio resources in
cooperative wireless networks. In the analysis of radio resources,
I investigate the diversity-multiplexing-delay (D-M-D) tradeoff
analysis of automatic retransmission request (ARQ) cooperative
channels. Diversity gain and multiplexing gain are two benefits
provided by fading channels. However, in order to achieve more
diversity gain, we need to sacrifice some multiplexing gain, and
vice versa. Therefore, the maximum diversity gain that can be
provided at each multiplexing gain is of course of interest to the
designer of wireless systems. The major contribution of this work
is that I derive the optimal D-M-D tradeoff curves for ARQ
cooperative broadcast channels with arbitrary number of receive
nodes and arbitrary maximum number of ARQ rounds. Interestingly, it
is shown that the achievable diversity gain is always restricted by
two special situations. The results are compared with previous
results on the achievable diversity-multiplexing tradeoff curves of
cooperative broadcast channels where no ARQ is taken into
consideration. It is shown that significant diversity benefit can
be provided by ARQ. Moreover, by utilizing the derived results, the
impact of the network geometry on the system performance is also
analyzed at high signal-to-noise ratio (SNR) region. In my research
on the allocation of radio resources, I devise power, sub-carrier,
and route allocation methods for cooperative multi-user OFDMA
(Orthogonal Frequency Division Multiple Access) systems. It is
shown that good allocation of radio resources in cooperative
multi-user OFDMA system can significantly enhance the system
performance by exploring the cooperative diversity and multi-user
diversity in the system. To achieve this objective, I propose novel
cooperation strategies and novel centralized resource allocation
algorithms in this thesis. The proposed cooperation strategies
achieve the capacity upper-bound when there are only two users in
the system. When there are more than two users in the system, they
can achieve near upper-bound performance in certain network
topologies. The proposed resource allocation algorithms are
developed via primal-dual decomposition and are capable of solving
relay selection, power and subcarrier allocation problems
simultaneously. The complexity of the algorithms increases only
linearly with the number of subcarriers in the systems. This is a
quite an important feature for future wireless OFDMA systems where
the number of subcarriers is usually large. A limitation of the
above allocation of radio resources is that it assumes full
instantaneous channel state information (CSI) of the system,
including instantaneous CSI between the source and the relays, are
available to the centralized controller (e.g. the basestation).
Such an assumption requires significant overhead when the channels
vary fast. Therefore I also investigate the scenario where only
long term CSI between the source and the relays are available to
the centralized controller. The conclusion provides guidelines to
the system designers so that they can decide whether the overhead
is worth for the performance enhancement. Finally, I investigate
the combination of resource allocation and interference
cancellation in cooperative wireless networks. Novel cooperative
protocol which utilizes self-information to subtract the
interference in two-way communication systems is proposed for
multi-user multiple-input multiple-output (MIMO) relay systems. An
adaptive relay power allocation algorithm is also developed based
on the proposed interference cancellation protocol to further
increase the system power efficiency. It is shown that the overall
protocol achieves more than 30% capacity gain compared to
previously multi-user MIMO cooperative protocols in various system
scenarios.
- Visits:
- 1
- Access:
- Instructions in case access is denied
Site powered by:
