A/Prof. Steve Weller
ResearchCurrent research projects Previous research projects Iterative subspace expansions for space-time adaptive wireless communications, radar and sonar
2009-2011 ARC Discovery Project Grant DP0986916, $270K
Chief Investigators: A/Prof. Peter Schreier and A/Prof. Steve Weller
Partner Investigator: Prof. Louis L. Scharf (Colorado State University)
This project addresses the fundamental challenge of high computational complexity in receivers for bandwidth-efficient, high data-rate wireless communications, radar and sonar. We study conjugate gradient Wiener filters that enable effective low complexity approximation if the signal correlation matrix has a small number of distinct or clustered eigenvalues. In this case, these filters converge with warp speed. Hence, by properly designing signal transmissions in multi-access communications, we can build receivers that rapidly adapt. A critical question is the sensitivity of repeated/clustered eigenvalues to perturbations, e.g., in time-varying communication channels. We analyse this question from the point of view of feedback control.
Dynamical systems and iterative decoding of low-density parity-check codes
2007-2009 ARC Discovery Project Grant DP0771131, $210K
Chief Investigators: A/Prof. Steve Weller and Dr. Chris Kellett
Modern communications is based on the premise that information represented digitally can be reliably transmitted, stored and reproduced. After some 50 years of steady progress in designing the error control codes needed to ensure integrity of data transmission and storage, breakthroughs in the late-1990s have used principles of iteration and feedback to push the theoretically achievable performance of low-density parity-check (LDPC) codes close to fundamental limits, though practical codes fall short of these limits. This project aims to apply techniques from the theory of nonlinear dynamical systems to analyse and design practical iterative decoding algorithms for next-generation digital communications based on LDPC codes.
New methods and microelectronics for wireless
2005-2009 ARC Linkage Project Grant LP0561092, $970K
Chief Investigators: A/Prof. Brett Ninness and Dr. Steve Weller
Partner Investigators: Dr. Graeme Woodward, Dr. Mark Bickerstaff and Dr. Adriel Kind
Industry Linkage Partner: Agere Systems Australia
Australian Postgraduate Award Industry (APAI) scholarships: Mr. Ian Griffiths and Mr. Alan Murray
Global demand for high quality wireless communications poses significant challenges. The so-called "physical layer" is crucial, as this is where the vagaries of the wireless channel, including interference and limited bandwidth, are mitigated by sophisticated signal processing. This project will conduct applied research to meet these physical layer challenges, providing solutions that feed directly into next generation wireless communication systems. Uniquely, this project focuses on the transfer of research from theoretical genesis, through to realisation of silicon integrated circuit "chips". This will maximise both the impact of the research and the potential for significant national economic benefits to accrue.
Structured low-density parity-check codes for next-generation
2004-2006 ARC Discovery Project Grant DP0449627, $257K
Chief Investigator: Dr. Steven R. Weller
Australian Postdoctoral Fellowship (APD): Dr. Sarah Johnson
The promise of essentially error-free information transmission is a cornerstone of digital communications. Next-generation applications demand increasingly effective error correction, yet at the same time traditional systems fall well short of fundamental capacity limits established some fifty years ago. Exciting breakthroughs were made in the mid-1990s, when capacity-approaching low-density parity-check (LDPC) coding schemes were discovered, along with other codes on graphs with iterative decoding algorithms. This project aims to apply techniques from discrete mathematics to design new LDPC codes. The outcomes of this research will be new LDPC codes, encoding algorithms and analysis techniques for next-generation communications.
Advanced space-time coded multiuser wireless communications via test-bed development
2002-2004 ARC Linkage Project Grant LP0211210, $269K
Chief Investigators: Dr. Brett Ninness and Dr. Steve Weller
Partner Investigators: Dr. Chris Nicol and Dr. Linda Davis
Industry Linkage Partner: Bell Labs (Lucent Technologies)
Meeting the global demand for mobile and wireless communications depends critically on reliable and high rate data transfer. Unfortunately, communications medium idiosyncrasies pose formidable challenges. Very recently, in combatting this, major breakthroughs have been achieved whereby the use of multiple antennas allows for drastic data-rate increases. These advances use sophisticated Space-Time coding methods, and while they are causing great excitement in terms of their simulation performance, it is not clear how they will perform in practice, or in fact how they are to be realistically implemented. This project will address this issue by building a testbed that implements a high rate wireless communications system using space-time and other coding methods.
2004-2006 ARC Discovery Project Grant DP0449627, $257K
Structural issues in control and state estimation for linear multivariable systems
1996-1998 ARC Large Research Grant A49601311, $165K
Chief Investigator: Dr. Steve Weller
Administering Institution: The University of Melbourne
The achievable performance of all control systems is necessarily constrained by the dynamics of the system being controlled. For multivariable (or multi-input, multi-output (MIMO)) systems, the nature of these constraints is considerably more complex than for scalar (or single-input, single-output (SISO)) systems, and present understanding is far from complete. The aim of this project is to investigate the role of the underlying zero structure of multivariable systems in delineating the achievable performance of feedback control and state estimation schemes. The expected outcomes of this project are control and estimation algorithms which exploit the underlying structure, and which give quantitative results on the achievable performance for both continuous-time and sampled-data model formats.
Current postgraduate students
- Ian Griffiths (PhD), principal supervisor Prof. Brett Ninness
- Elizabeth Ratnam (PhD), co-supervised with A/Prof. Chris Kellett
Graduated postgraduate students
- Alan Murray (PhD), graduated 2013
- Ray Brown (M.E.), graduated 2010
- Xinzhi Yan (PhD), principal supervisor Dr. Jamil Khan, graduated 2010
- John Dalton (M.E.), graduated 2010
- Geoff Knagge (PhD), co-supervisor Prof. Brett Ninness, graduated 2008
- Daniel Hall (M.E.) principal supervisor Dr. Jamil Khan, graduated 2008
- Sarah Johnson (PhD), graduated 2004
- Khusro Syed Saleem (PhD), graduated 1998
- Stephen To Wei Mun (MEngSc), graduated 1996
- Research overview talk at the Australian Communications Theory Workshop (AusCTW'05), 2-4 February 2005, Brisbane, Australia:
- Presentations for the Centre for Integrated Dynamics and Control (CIDAC) Kalman Filter short course, 8-9 November, 2001, Newcastle, Australia:
- Workshop presentation at 33rd IEEE Conference on Decision and Control (CDC'94) on Logic-based Switching Strategies for Self-adjusting Control, jointly presented with A.S. Morse (Yale University) and F.M. Pait (Universidade de Sao Paulo), 14-16 December, 1994, Lake Buena Vista, Florida:
- Structural issues in control design for linear multivariable systems, PhD thesis, December 1993.