Coding and Signal Processing For Future Fibre-Optical Communications
Optical communications offers many advantages compared to its radio frequency counterpart. Optical carriers have a much higher carrier frequency, allowing for significantly higher information bandwidth. Currently, technological advance in optical communications is overwhelmingly driven by breakthroughs in physics and photonics. As photonics technologies mature, and data rates increase, higher-order nonlinear physical effects and dispersion in the medium cannot be ignored (especially for long-haul transmission). Advanced digital coding and signal processing techniques become increasingly relevant to address these channel impairments. The aim of this project is to answer the most basic information theoretic questions concerning data transmission over optical channels. The emphasis is on mathematical foundations informed by sufficiently accurate physical propagation models.
The project will
- Develop the information theoretic tools required for analysis of nonlinear optical channels
- Determine the fundamental limits imposed by physics on information transmission over fibre channels
- Develop new information theoretically optimal coding and modulation techniques for optical communications
Information theoretic security and privacy
Dr Siu-Wai Ho
Information theoretic security relies on no assumption on the computational power of the adversary. Since the seminal work by Shannon in 1949, a lot of important results have been developed. Recently, we have a breakthrough by showing a new fundamental relationship between key size and message size. A new concept about the consumption of a secret key has been developed.
This project explores other fundamental questions in this new direction. The results can be applied to security problems and also the protection of privacy when we use the Internet.
Refinement of fundamental tools in information theory
Dr Siu-Wai Ho
In information theory, many famous tools or results cannot be applied to countably infinite alphabets, e.g., strong typicality, fans inequality and one-time pad. It is important to consider countably infinite alphabets because this is the general case and this usually gives tighter bounds, faster convergent rates, etc. Recently, we have generalized the aforementioned tools to countably infinite alphabets.
This project aims to generalize more fundamental results in information theory. Students with good mathematical and analytical skills are preferred.
Network information theory
Dr Roy C. Timo and Dr Badri Vellambi
Information theory (or Shannon Theory) is the mathematical study of information transmission, processing and utilisation. An overarching goal of this theory is to determine exactly how much information can be (or should be) transmitted in a telecommunications network. Information theorists formally referred to this goal as: "the characterisation of the admissible rate region of a network."
Over the past half century, information theory has been tremendously successful in characterizing admissible rates for point-to-point telecommunication networks involving one transmitter and one receiver. Unfortunately, the theory appears to be ill-equipped for telecommunication networks with multiple users. A unified theory to study the problems of multi-user information theory is yet to be realised. This project is devoted to the formalisation and characterisation of new notions of admissible rate regions of longstanding open multi-user network problems and the collective tools required to attain them.
Partial rate region characterisations: new frontiers of information theory
Dr Siu-Wai Ho, Dr Badri N. Vellambi, and Dr Roy C. Timo
Rate regions define the fundamental limits of applications in different areas, including data networks, wireless communications, and security systems. However, techniques of information theory are unable to completely characterise these regions for every application. Our aim is to develop methods for analysing rate regions that do not rely on complete characterisations. These methods will revolutionise our understanding of rate regions by bypassing the difficulties of existing techniques.
Outcomes will provide practically relevant properties of rate regions that will enable novel applications in communications systems.
Information theoretic security for networks
Dr Terence Chan and Professor Alex Grant
Network coding opens the door to many interesting possibilities for information security. The use of multiple transmission paths may increase robustness to denial of service or jamming attacks. It can also provide security against eavesdroppers.
Explores some of the security implications and advantages of network coding.
Network coding for multimedia multicast
Dr Terence Chan, Dr Roy C. Timo and Dr Badri N. Vellambi
Network coding is a recent breakthrough in telecommunications network research. Some attractive features of network coding include the efficient use of network resources, higher data throughput rates and increased robustness against network errors. Network coding is particularly effective in multicast scenarios, where many users require the same data from a single source. For example, consider streaming multimedia data over the internet from a single source to multiple users.
Investigate the application of network coding principles to the transmission of multimedia data in telecommunication networks. Of particular interest are situations where users require multimedia data at different fidelity/resolution levels. For example, some users may require high-quality video for high-resolution displays, while other users will require low-fidelity video for small mobile devices. The main purpose is to devise schemes for efficiently transporting multimedia data from a single source to many users with different fidelity requirements.
Wireless network coding
Dr Terence Chan, Professor Alex Grant
Network coding is a recent breakthrough, which uses coding rather than routing at the network layer for data transport. It has many advantages, including higher throughput, lower delay, and increased robustness This project investigates the application of network coding to ad-hoc wireless communications networks. The goal is to use network coding, rather than complex ad-hoc routing protocols. It has already been realized by several researchers that the wireless channel itself can act as a kind of "free" network coding device.