The aim of this project is to customise current satellite modem development to produce high performance, bandwidth efficient satellite modem, incorporating latest turbo coding error correction.
The application is a full mesh interconnected VSAT network system that uses MF-TDMA along with SCPC overlay for on demand or reconfigurable high speed data links. The modems incorporated advanced coding technology. The modulation and coding rate can be configured in real time for every on-demand link to meet the instantaneous throughput requirements using the available satellite capacity.
ITR has worked on a number of R&D projects in the area of bandwidth efficient communications over nonlinear satellite channels. One project investigated predistortion techniques that allow 16QAM turbo coded systems to operate close to the saturation point of a nonlinear amplifier. The proposed schemes achieve a more efficient utilisation of the space segment. The outcome was proof-of-concept hardware. This hardware also included turbo-like coding technology, developed at ITR,that allows quasi-error free communication at less than 1 dB from channel capacity.
The work extended previous research to more complex techniques such as iterative demapping and decoding, centroid estimation and turbo equalisation of 16QAM signalling over nonlinear satellite channels. In conjunction with predistortion techniques, the schemes investigated achieve very high performance.
An investigation into methods of dealing with phase noise and frequency offsets in iteratively decoded systems so that performance loss due to the phase disturbances is minimized.
Design of a Satellite Baseband Switch for regenerative satellite operations.
Applied research and development contributions to the systems that support swarms by using reconfigurable computing. The project aims to deliver a pilot high speed, low power radio network, and a sensor sharing and processing system that will enable the swarm to track events such as bushfires.
On a global scale, traffic accidents are one of the leading causes of serious injury or even death. In 2004, the World Health Organization estimated that 1.2 million people lost their lives in traffic accidents around the world, making it the ninth leading cause of death worldwide. It is projected that traffic accidents will grow to be the third leading cause of death in the world by 2020.
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 Institute for Telecommunications Research (ITR) and its 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.). This is however a very challenging networked environment, consisting of very many moving vehicles, with uncertain locations. 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.
Advances in the development of special-purpose wireless ad hoc networks will provide opportunities for emerging wireless applications. Example applications with significant relevance to Australia include public safety and emergency-area communications. Cooperative communications is a new technology specifically targeting performance improvements in wireless ad hoc networks.
The aim of the project is the design, evaluation and implementation of efficient transmission strategies for reliable communication across cooperative wireless ad hoc networks. The project focuses on the innovative use of channel and network coding techniques to increase reliability, throughput, and coverage of cooperative wireless ad hoc networks.
The main task is to devise new transmission strategies for application across all nodes within a cooperative wireless network of arbitrary size and topology. The emphasis will be on efficiency, simplicity, and scalability to allow for practical implementation. Two key concepts are to employ multi-layer transmission schemes for cooperation and to exploit inherent properties of wireless channels for network coding.
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.
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 particularly interesting for multicast scenarios, where many receivers require the same data from a single source. In this project, we will investigate the application of network coding to distribution of multimedia traffic. It is of interest to consider receivers with different capabilities that may require different resolution versions of the same source data. One example would be streaming a video source, where some receivers have high-resolution displays, and others are small mobile terminals.
The objective is to develop rateless network codes supporting this kind of multi-resolution streaming data.
Various investigations and assisting client by improving knowledge in the area of network coding – an emerging area. Areas of interest include understanding network performance that is achievable with multiple traffic sources – in particular networks with error free point-to-point links.
In association with researchers in National ICT Australia, study general areas of fundamental communication limits and their applications. This work uses information theory principles to better understand the fundamental properties and capacities of wireless communications systems.
Computational neuroscience is the collective name for scientific research into understanding the brain that employs tools familiar to mathematicians, physicists, computer scientists and electronic engineers. Our brains operate very differently to digital electronic computers. One of the goals of computational neuroscience is to understand the physical mechanisms biology uses to acquire, process, communicate and compute information.
One way to better understand our senses and neural coding is to model and analyse, using information theory, the features that are also present in artificial communication or sensor networks.
A Stochastic Pooling Network is a model that can be used to understand complex nonlinear interactions between random noise, redundancy and compression. The model is applicable in many situations, for example biological neural populations, nano-electronic circuits and distributed sensor networks.
There are many interesting possibilities for theoretical research in this area, for students with backgrounds in any of the following areas: mathematics (pure or applied), numerical computing, information theory, electronic engineering or physics.
The project produced a snapshot of the current state-of-the-art of wireless communications technologies (including companies, institutes and researchers who are highly influential in this field), and likely advances in this technological area over the 5, 10 and 20 year time periods. The identified technological barriers towards achieving these advances, and provide insight on the possible effects and implications envisaged advances will have.
This project studied a number of different aspects relating to links that can be used for inter-satellite communications. This included orbit modelling, adaptive link analysis, link design and initial work in identifying potential preliminary designs and a review of antenna technologies.
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. This will involve collecting sample measurements from simultaneous FSO and Ka-band RF transmissions over a long propagation distance (approximately 20km) and mathematical modelling of the observed data.
The use of MIMO and hybrid RF/FSO techniques has great potential in significantly improving the reliability of free-space optical communication. However, very little is known on how to efficiently transmit information reliably using these channels.
This project will involve an information theoretic analysis of these channels to determine key design parameters that underpin efficiency and reliability of the transmission of information. In particular the project will investigate the affects of non-ideal photo detection, scintillation, spatial and temporal correlation on the fundamental limits of FSO communication. Novel transmission strategies will then be investigated that achieve as close as possible to these fundamental limits, whilst remaining feasible to implement in practice.
This project addressed issues in integration of rapidly developing wireless (mobile) terrestrial broadband data access technologies with global coverage satellite data services.
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.
However the 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. In large sensor networks, it is not realistic to envisage that a central entity would be capable of coordinating all tasks performed by a very large number of sensor nodes. Instead, they require distributed medium access and routing mechanisms to function effectively.
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 this project an array of several microphones, together with suitable amplifiers and a sampling system with PC interface, are used to explore the performance of signal processing techniques for noise suppression by beam-forming. Signals are recorded in real acoustic environments, such as teleconference scenarios, and processed offline using Matlab. The degree of wanted signal enhancement, plus the effects of reverberation and speaker movement are explored.
One project resulted in the design, development and manufacture of a digital demodulator that is capable of receiving the following satellites up to approximately 25 Msym/s. These include: EOS AM1, EOS PM1, METOP-HRPT, NOAA HRPT, CHRPT, GMS, GOES GVAR, MTSAT-HRIT and MTSAT LRIT.
A product was developed in a small form factor that allows the unit to fit easily into a full height CD player size PC bay. A requirement from the customer, was the use of TCP/IP over 100 Mbit/sec Ethernet as the primary data output mechanism. This approach allows a tighter integration of the demodulator output to the follow-on processing tasks, which are typically handled in software. Another advantage of this technique is that the receiver may be controlled remotely over a TCP/IP network. The demodulator control software runs on a highly integrated embedded microprocessor running the Linux operating system. A significant advantage of using Linux is its extensive built-in support for TCP/IP, which is used to control the receiver and provide the receiver's main data output port.
In addition, ITR has developed a very flexible multi-channel, high rate (1 Gbit/s) demodulator for another client, Satellite Services BV (Netherlands). The state-of-the-art demodulator integrates with Satellite Services ground station equipment and standard user interfaces.