Journal Publications
Conference Publications
Simulation Package
Research Activities
(1) Coding and modulation schemes for communication
systems
Coding and transmission techniques are crucial in modern communication systems.
The progress in information theory and signal processing techniques has a
tremendous impact on coding and modulation techniques. Recent advent in
iterative decoding, codes on graphs, hybrid coding/modulation and loss recovery
codes have shown that both capacity and performance of communication systems can
be significantly enhanced. We have developed some very low complexity code and
hybrid coded modulation methods, which can be ten times cost effective than the
best existing schemes, yet with comparable or even better performances.
(2) Multiple access techniques of wireless cellular
communication systems
The capacity of a cellular mobile communication system is limited by multi-user
interference, from both same-cell users and other-cell users. Multiple access
techniques, such as FDMA, TDMA and CDMA, are techniques to treat this
interference problem. One basic approach (such as FDMA and TDMA) is to prevent
interference by adopting orthogonal waveforms. Another quite different approach
(such as CDMA) is to use random signals so as to reduce the correlation among
signals from different users. Interference cancellation methods have also been
widely studied to handle the problem. Our work in this area has revealed that
the advantages of these methods can be combined so that the system architecture
can be much simpler, the transmitter and receiver can be considerably simpler,
and the performance can be greatly enhanced.
(3) Transmission and routing techniques for
Internet and wireless data networks
As the broadband Internet keeps increasingly growing at speed, delivery of
multimedia contents is expected to be one of the most popular broadband services
in the near future. Handling multimedia contents is a very challenging issue as
it involves a huge amount of storage capacity and a very wide transmission
bandwidth. The current Internet architecture, however, uses a best effort
delivery. It is not optimized for delivering multimedia contents because all
types of data are treated as the same. To improve the performance of data
delivery, designers of communication systems must pay special attention to each
type of multimedia content. The delivery systems designed must also handle each
type of contents in a unique way so as to provide optimal performance. Such
systems can be called "content based multimedia delivery systems". We are
currently studying and developing design strategy, performance analysis and
demonstration prototypes for such systems.