Many applications, including meteorology, remote sensing, irrigation, mining, oil and gas exploration, and fisheries, preclude the use of consumer-oriented terrestrial wireless broadband services because of the remote and distributed locations involved. In these situations, satellite communications provides the only feasible means of providing connectivity for telemetry, supervisory control and data acquisition, tracking and fleet management.

This project will develop novel bandwidth efficient satellite communications technologies, and it aims to extend both basic understanding and engineering practice for satellite modems. Project outcomes will include fundamental contributions to the theory of information transmission, new coding and decoding methods for satellite communications and a proof-of-concept implementation demonstrating benefits in real-world conditions.

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.

Cooperative wireless ad-hoc networks are a promising novel technology for future communication networks. They can provide an information infrastructure for applications like vehicular-safety systems or emergency-area communications; and they can also extend coverage and ?exibility of existing networks. Wireless ad-hoc networks are formed by wireless and possibly mobile terminals that act as network nodes. These terminals assist each other to relay information packets in a multi-hop fashion across the network.

The project deals with the design, evaluation and implementation of transmission strategies for reliable communication across cooperative wireless ad-hoc networks. To achieve high efficiency, we focus on the innovative use and combination of concepts like channel coding, network coding, relaying, and distributed MIMO transmission. The main task we address is to devise new transmission strategies for application across all nodes within a cooperative wireless network of arbitrary size and topology.

On a global scale, traffic accidents are one of the leading causes of serious injury or even death. Recent advances in wireless communication technology, e.g. WiFi or Wireless LAN, have revolutionized personal mobile connectivity. In much the same way, these technologies are on the verge of revolutionizing wireless inter-vehicular communication. In particular, Dedicated Short Range Communications (DSRC) is emerging as the communications standard for future intelligent vehicle systems. These systems are currently being adopted around the world as a means to: improve safety and save lives lost to traffic accidents; reduce the economic impacts of traffic accidents and congestion; reduce the environmental impact of congestion.

The ITR and industry partner Cohda Wireless are pioneering state-of-the-art DSRC technology that uses the latest IEEE 802.11p standard to enable wireless vehicle-to-vehicle communications. With this technology, each vehicle is able to broadcast its position, velocity and direction information to all other vehicles within a certain range. Each vehicle is thus able to integrate this information with map data to build up a picture of the traffic environment, which can then be used to warn the driver of potential hazards (e.g. collisions, corners, traffic lights, give-way/stop signs etc.). The aim of the project is to develop robust approaches for ad-hoc vehicular networks, and integration of inter-vehicular communication and geographic information to provide novel hazard avoidance technology.

Space-time processing (using multiple antennas) is now recognized as a key to achieving reliable high data rate wireless communications and is being incorporated into the physical layer of many wireless standards. In this project we have introduced another degree of freedom: electromagnetic polarization.

At ITR, we are developing new algorithms and power-efficient hardware architectures for signaling, detection, demultiplexing, and decoding. In collaboration with the University of Melbourne, Princeton University and DSTO, these elements are incorporated into a cross-layer approach to utilizing polarization as a new resource for wireless access to broadband in the bush.

Wireless data communications is becoming ubiquitous. To meet the demands of future high-speed wireless applications, systems are approaching fundamental physical limits, where implementation complexity is a major problem. Iterative information processing has emerged as the dominant low-complexity design paradigm.

The aim of this project is the optimization of data communications systems subject to constraints on computational complexity. The project builds on previous research accomplishments in these areas, aiming to formally include complexity constraints into the design of concatenated coding systems, and into the development of low-complexity iterative algorithms. The main research tasks are to formulate a mathematically tractable measure of complexity relevant for concatenated systems and corresponding iterative processing algorithms, and to incorporate this analytical complexity measure into the design of optimal, complexity-constrained code structures.

With higher data rates in wireless communication networks, new broadband services like DVD-quality video and CD-quality audio become relevant for wireless devices. Each application requires the network to deliver a specific Quality-of-Service (QoS) in terms of minimum errors and delay. A major network design challenge is to provide a wide range of QoS, given the limitations of wireless channels, and the limited available resources. Transmission schemes, adapting to instantaneous channel characteristics can significantly improve performance.

The main objective of this project is to increase the throughput of future wireless communications systems by adopting adaptive principles in the underlying communications protocols. The specific aims are to determine optimal adaptive transmission strategies for delay-limited block-fading channels, minimizing the outage probability; extract design guidelines for adaptive transmission schemes through a thorough theoretical understanding of the outage probability; and develop practical adaptive, low-complexity coding and decoding strategies that can perform arbitrarily close to the outage probability for delay-limited block-fading channels.

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.

Firstly, we will aim to find information-theoretic bounds on the throughput and reliability of wireless network coding. Secondly, we will aim to devise practical transmission schemes to exploit this possibility. Experimental work will be carried out using the SANLAB mobile ad-hoc networking laboratory. This project involves collaboration with researchers from Adelaide University and DSTO.

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.

The project explores some of the security implications and advantages of network coding.

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.

In this project, we will 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 of this project is to devise schemes for efficiently transporting multimedia data from a single source to many users with different fidelity requirements.

ITR has developed a novel opportunistic rate adaptive medium access control protocol suited for ad hoc communication networks. The objective of this project is to develop "opportunistic routing" protocols to take advantage of the new MAC protocols. In this project we will attempt to identify the end-to-end "goodness of transmission conditions" along different paths between a given source and destinations. Once these have been estimated they will be compared to the requested Quality of Service (QoS) between a source and destination. The path that closely matches the QoS requirements can then be selected as the primary route between the source and destination.

Research problems that will be addressed in this project include methods to estimate the "goodness of transmission conditions" between a given source and destination (this will be an extension of probability of good channel conditions in the current MAC protocol), effective collection and exchange of information required to create such measures and characterising QoS requirements of different nodes.

Recent advances in mobile communication technology, efficient/portable power sources, and high speed computing have enabled the deployment of sensor and ad hoc networks, which are a collection of wireless terminals that can form a network in the absence of any fixed infrastructure support. Ad hoc networks have applications in defence and various emergency services. Recently, sensor networks have emerged as another interesting application of telecommunication networks, where a large number of sensors form a network to collect, process and distribute information. Theoretical and mathematical understanding of these networks is still in its infancy. Due to the lack of a solid theoretical understanding, the performance of current implementations of both ad hoc and sensor networks has fallen well below the generally expected performance.

The aims of our project are to develop a theoretical framework and use this to study the performance of sensor networks and the impact of selected network parameters (e.g. node density, power allocation, interference) or protocol mechanisms (e.g. routing, resource allocation) on the overall network performance. This will also lead to understanding inherent performance limitations of sensor networks. In addition, we will design distributed network protocol mechanisms, which optimise the network performance.

In Free-Space Optical (FSO) communication, information data is transmitted wirelessly using laser beams. Such links have the potential to provide virtually unlimited bandwidth without the expense of buried fibre optic cabling. Unfortunately, FSO link reliability is highly dependent on atmospheric conditions such as turbulence, rain, cloud, dust and fog. These effects cause fading of the received laser beam. In typical FSO channels, a deep fade can cause the loss of millions of data bits. Improvement in reliability can be gained by using multiple lasers and multiple apertures to create a multiple-input multiple output (MIMO) FSO channel. However, the atmospheric effects in multiple-laser, multiple-aperture FSO systems are largely unknown, and experimental analysis is lacking.

A comprehensive characterisation of this channel will be crucial in order to exploit the full capabilities of MIMO FSO links. This project investigates these aspects by collecting channel measurements from both terrestrial and (if available) satellite-to-ground FSO links equipped with multiple-lasers and multiple detectors. Key parameters of interest are the temporal and spatial fading and background noise statistics under a range of climatic and environmental variations, including daily and seasonal variations for both clear-sky and impaired situations due to dust or clouds, for a variety of propagation lengths. Using these channel measurements, statistical models will be developed that describe the spatial-temporal behaviour of MIMO FSO channels.

Although free-space optical (FSO) links can usually support huge data rates, their performance is affected by fading due to atmospheric turbulence, plus meteorological conditions such as dust, clouds and fog. Whilst fading due to atmospheric turbulence can be mitigated using multiple-lasers and multiple-apertures, the large signal attenuation due to fog and cloud cover poses a formidable challenge. It appears the only way around these problems is to use an additional radio frequency (RF) link, creating a hybrid FSO/RF channel. In particular, high frequency Ka-band (18-40 GHz) or V-band (40-70 GHz) links are most favourable for this purpose to maintain data rates comparable to that of the FSO link.

At these frequencies, the FSO and RF channels operate in a complementary manner to each other. For example Ka-band RF links are less affected by fog or cloud, but can be seriously degraded by rain. FSO links do not penetrate fog/cloud well, but are reasonably resilient to rain. Thus, practical FSO systems are likely to use a hybrid approach that intelligently combines the advantages of FSO and RF links. Despite the obvious intuitive advantages of hybrid FSO/RF links, little is known regarding how to model the combined statistical behaviour of the component channels, and even less is known on how to efficiently combine them to improve system reliability. The aim of project is to characterise the joint statistics of hybrid FSO/RF channels under a variety of atmospheric conditions.

Communications technology and biological brains share many common features. Brains have evolved ways to (i) acquire information (sensory transduction), (ii) communicate between brain regions (information transmission) and (iii) form and recall memories (information storage). Improved knowledge about these processes is essential for understanding how our brains "compute." There is a particularly pressing need to understand the roles of neuronal oscillations. These "brain rhythms" are thought to be critical for communication between distinct brain regions, and for memory storage and recall.

There are two goals in this project. The first is to introduce communications engineering concepts, tools and metrics to studies of communication within the brain. The second is to apply resulting insights to the development of bio-mimetic technology. Recent studies of "brain rhythms" have already been applied in engineered sensor networks, and other applications are likely. This project will therefore contribute to future communications and computation technology, as well as "neural engineering" techniques for enabling direct communication between neurons in the brain and external electronics, such as "bionic eyes" and brain-signal controlled machines.