Communications and Networks Research Lab


Researchers in the Communications and Networking Laboratory are actively engaged in addressing key challenges that face the future generation broadband communication networks.

More specifically, researchers in the wireless communications and networking area are investigating design and fundamental information-theoretic analysis of energy efficient next generation wireless networks that can deliver very high data rates anytime anywhere, via the MIMO-OFDM technology proposed for the new wireless communication standards such as Long-Term Evolution — Advanced (LTE-A), and re-thinking of cellular network design via a hierarchical structure involving macro, micro, pico and femto-cells.¬†Emerging technologies such as cognitive radios are also being investigated to address the problem of spectrum scarcity. A number of researchers are also investigating how to design more energy efficient wireless video communication networks.

Researchers in the optical communications domain are investigating the problem of reducing the carbon footprint of the next generation Internet (for more information, see Centre for Energy-Efficient Telecommunications), along with the design and analysis of broadband networks that seamlessly integrate wireless and optical communications technologies via Passive optical networking (PON). Networking researchers are investigating practical inference methods for Internet measurement, sophisticated accurate clock synchronization techniques over the Internet and aspects of Information-theoretic security.

More details on these and other related projects can be found in the following list of projects.


Codes over rings

Researchers: Margreta Kuijper

This project focuses on algebraic codes over finite rings of the type Z_{p^r}. In recent years, novel linear algebraic tools were developed that overcome the difficulties of the presence of zero divisors in such rings.

Current research is focused on further application of these fundamental ideas. We consider the design of efficient algorithms for decoding of Reed-Solomon codes over rings; network coding over finite rings; shortest recurrence algorithms for sequences over rings; non-Hamming metric decoding over finite rings.

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Easing the squeeze: dynamic and distributed resource allocation with cognitive radio

Researchers: Tansu Alpcan, Subhrakanti Dey

The radio spectrum is a scarce and valuable natural resource which is being squeezed by the rapid growth in wireless communications. Cognitive radios make efficient use of radio spectrum by dynamically reusing frequencies. This requires cognitive radios to sense the local environment and to control the interference caused to existing users of the spectrum. In this project we will design novel dynamic and distributed resource allocation algorithms for cognitive radios in order to significantly improve their performance. We will do so using techniques from extreme value theory, game theory and mechanism design and large random
matrix theory.

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Gigabit wireless access using millimeter-wave over optical fiber systems

Researchers: Masud Bakaul, Thas Nirmalathas, Christina Lim, Stan Skafidas

Millimeter-wave radio-over-fiber (RoF) systems are widely considered as a disruptive technology for Gigabit/s wireless communications. In these systems, the benefits of optical fiber and mm-wave radio technologies are combined to provide an alternative approach for high-speed wireless access to customers. An optical fiber feeder network is used to interconnect a large number of remote antenna base stations (BSs) to the local Exchange (central office, CO), where most of the switching and signal processing equipment are installed. Usual distances between the CO and the BSs and the BSs and the customers are 5-50 km and 10 -1000 meters respectively. This project explores various system technologies and architectures in simplification of optically modulated millimeter-wave generations, transports and detections that enable Gigabit wireless access potentially at low-costs.

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Internet Measurement

Researchers: Darryl Veitch

Internet Measurement is a rich field devoted to the development of accurate experimental, measurement, analysis and inference techniques to shine light into the vast unknown that is `what is going on in the Internet'. 

This project pursues several strands, including:

  • Active probing:  this is the practice of sending streams of `probe' packets into the network, to infer network behaviour through observing their end-to-end experience (if they are lost, delayed..).  The current focus is to explore the `convex network' approach to solving problems in optimal probing (getting the most information per-probe).
  • Traffic Sampling:  in high speed environments like inside routers in the Internet core there are far too many packets to measure them all.  We research optimal sampling, sketching, and `skampling' techniques to measure metrics like the flow-size distribution at ultra high-speed with minimum variance.
  • Optimal Traceroute:  Traceroute is a well-known tool for measurement of the paths that packets take when traversing the Internet. The project refines its operation to provide statistical guarantees when used for topology discovery.

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Internet of Things for Creating Smart Cities: Designing an urban information architecture

Researchers: Jayavardhana Gubbi Lakshminarasimha, Marimuthu Palaniswami, Jayavardhana Gubbi, Slaven Marusic

The project aims to create a Smart City capability through seamless urban environment monitoring via large-scale sensing, data analytics and information representation. Interconnection of sensing and actuating devices as an ‘internet of things’ addresses the ability to share information across platforms through a unified framework, developing a common operating picture for city management. The interpretation of events and visualisation of information for end-users will ensure sustainability and higher quality of life in the urban environment. Major outcomes will include energy-efficient sensing, network quality of service, cloud computing for sensor networks and high level analytics to detect and interpret events for decision making.

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Large scale multiple antennas for energy-efficient heterogeneous wireless networks

Researchers: Phee Lep Yeoh, Brian Krongold

This project investigates new network architectures for future wireless broadband inspired by recent advances in large scale multiple antenna technology and heterogeneous networks. The aim is to support flexible and scalable wireless services across diverse network regions with energy-efficient management of radio spectrum and interference. Targeted applications include smart energy metering, intelligent transport systems, mobile health monitoring and green data centres. Outcomes of the research will be new wireless protocols and algorithms drawing upon the foundations of random matrix theory, game theory, and large system analysis, which will offer fundamental insights into large scale multiple antennas for heterogeneous wireless networks.

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Network Timing System

Researchers: Darryl Veitch, Julien Ridoux

This project aims to develop the next generation system for computer clock synchronisation for the Internet.  Our goal is to replace the incumbent, the `NTP' system, currently used by (almost) every computer on earth.

All computers incorporate a software clock, essential to software applications. An inexpensive and convenient way to synchronise such clocks is over a network, however the approach the Internet currently depends upon is unreliable, inflexible, and ignores major sources of error. This project will define and solve the key research problems underpinning an optimal and maintainable system for network timekeeping, and implement and test the outcomes under realistic conditions over the Internet. The result will be software clocks of high accuracy and reliability supporting applications like cloud computing, tele-medicine, smart grids, and network measurement, well positioned to become the next generation timekeeping system for the Internet.

This project builds on the existing testbed and RADclock synchronisation client developed under the SyncLab project.  Open Source software is available for download at  Support for RADclock has been accepted into FreeBSD, the operating system of choice for servers.

Current directions:

  • Virtualised OSs     ( timing architecture for virtual machines )

               Virtualisation-friendly timing including live migration;  testing on Xen, VMware Player

  • Asymmetry measurement and mitigation   ( large error, largely ignored )

               Tightening bounds via spatial diversity; OS calibration; server recommendation service 

  • Server heath monitor   ( remote assessment of time-server quality )

               Exploiting known RADclock performance to detect server anomalies

  • Timing system health   ( evaluating systemic anomalies and performance )

               Mapping and evaluating public stratum-1 servers; assessing vulnerabilities

  • IEEE-1588 (PTP) support   ( exploiting 1588 masters for software clocks )

               Benchmarking 1588-capable RADclock against alternatives; contributions to standard

  • Unidirectional feed-forward algorithms   ( currently RADclock is bidirectional )

               Currently only feedback algorithms exist, unstable to noise (latency variability)

  • RADclock performance   ( formal analysis and performance enhancement )

               Statistical analysis of algorithms (for optimisation, calibration..);  LAN-specific enhancements

  • Adoption   ( building momentum towards replacing the NTP system )

              Accepted into FreeBSD 10.0; visibility with Linux stakeholders; adoption by CAIDA’s Ark monitors

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Network Tomography

Researchers: Darryl Veitch, Julien Ridoux, Salman Malik

Internet Tomography is the name given to a class of statistical inference problems where Internet measurements made over accessible `slices' of the network are used to infer quantities over other, inaccessible slices. Classic examples include measuring aggregrate traffic at routers inside the network to infer end-to-end traffic demand, or measuring end-to-end delays at measurement stations at the edge of the network to infer delays at nodes inside it. 

This project researches a number of Internet Tomography problems.  The main focii currently are:

  • Exploiting sparsity for loss tomography (in a nutshell, working out how to predict loss `hotspot' locations assuming there aren't many of them).
  • Investigating joint compressibility for topology inference (working out how the network is connected by observing the similarities in the structure of observed packet losses at different locations).

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Precision Timekeeping Infrastructure: bridging the hardware/software divide

Researchers: Julien Ridoux, Darryl Veitch

Accurate time is essential for critical services from telecommunications to banking, and increasingly, must be performed with software clocks within computers, using hardware clocks accessed over the Internet. This project with Symmetricom Inc. will bridge the hardware/software divide to deliver reliable and cost effective access to precise timing. 

The project builds on the existing testbed and RADclock capabilities with the broader SyncLab project.  Its focus is on working to brings software based timekeeping on a LAN (Local Area Network) down to the 1 microsecond level.


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The impact of the mass adoption of electric cars on the Australian electricity grid

Researchers: Iven Mareels, Doreen Thomas, Marcus Brazil, Kevin Prendergast, Tansu Alpcan, Julian de Hoog

This project will study the impact of the mass adoption of electric vehicles (EVs) on the electricity grid.  The success of the uptake of EVs promises significant greenhouse gas reduction but depends on making it convenient and affordable for motorists to move away from the use of fossil-fuelled vehicles.  The electricity grid infrastructure required to realise the full potential of EVs will be quantified, both from a traditional as well as a smart grid perspective.  The impact of this fleet on the power management of the distribution network and power quality will be analysed.

Specific research goals include:

  1. Identification of limitations in the current distribution network with respect to EV charging
  2. Development of an optimal charging policy for demand aggregators
  3. Evaluation of the benefits of the charging policy with respect to variable (green) power sources

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Contact Us

Assoc Prof Elaine Wong

Director, Communications and Networks