Publications

Gerber, R & Braun, R 1998, New Connections Telecommunications in a Changing South Africa, University of Cape Town Press (ZA).
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Written for students as well as business managers in telecommunications industries, this book investigates the telecommunications sector worldwide, and includes a detailed study of the South African perspective.

Abry, P & Veitch, D 1998, 'Wavelet analysis of long-range-dependent traffic', IEEE Transactions on Information Theory, vol. 44, no. 1, pp. 2-15.
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Abry, P, Veitch, D & Flandrin, P 1998, 'Long‐range Dependence: Revisiting Aggregation with Wavelets', Journal of Time Series Analysis, vol. 19, no. 3, pp. 253-266.
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The aggregation procedure is a natural way to analyse signals which exhibit long‐range‐dependent features and has been used as a basis for estimation of the Hurst parameter, H. In this paper it is shown how aggregation can be naturally rephrased within the wavelet transform framework, being directly related to approximations of the signal in the sense of a Haar multiresolution analysis. A natural wavelet‐based generalization to traditional aggregation is then proposed: ‘a‐aggregation’. It is shown that a‐aggregation cannot lead to good estimators of H, and so a new kind of aggregation, ‘d‐aggregation’, is defined, which is related to the details rather than the approximations of a multiresolution analysis. An estimator of H based on d‐aggregation has excellent statistical and computational properties, whilst preserving the spirit of aggregation. The estimator is applied to telecommunications network data.

Andren, J, Hilding, M & Veitch, D 1998, 'Understanding end-to-end Internet traffic dynamics', Conference Record IEEE Global Telecommunications Conference, vol. 2, pp. 1118-1122.
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An investigative tool for the direct study of end-to-end Internet traffic is presented, featuring a hybrid timing mechanism allowing high resolution timestamping of packet departures in a UNIX environment. A method for the elimination of timing artifacts due to variations in clock rates, essential for the study of delay, is also presented. A preliminary report is given on the detailed structure of end-to-end delay and loss processes using the tool. A number of consistent properties of interest are found including long range dependence in delay and a very simple structure for loss.

Butchart, K & Braun, RM 1998, 'An adaptive modulation scheme for low Earth orbit satellites', Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214), vol. it 33, pp. 43-46.
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Cucchiara, R, Neri, G & Piccardi, M 1998, 'A real-time hardware implementation of the hough transform', Journal of Systems Architecture, vol. 45, no. 1, pp. 31-45.
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The paper presents a hardware implementation of algorithms based on the Hough transform (HT) for real-time straight line detection. In particular, the basic HT on the edge points (EHT) and the Gradient-Weighted Hough transform (GWHT) for gray-level image

Cuthbert, JA & Braun, RM 1998, 'Selection of Multi-h modulation sets using a stochastic search algorithm', IEE PROCEEDINGS-COMMUNICATIONS, vol. 145, no. 1, pp. 41-46.
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Multi-h CPFSK modulation is simple to implement, spectrally efficient, and has inherent error correction properties. Multi-h requires large parameter sets to obtain high coding gain. Large numbers of combinations may need to be investigated. A fast effic

Keenan, T, Glasson, K, Cummings, F, Bird, TS, Keeler, J & Lutz, J 1998, 'The BMRC/NCAR C-band polarimetric (C-POL) radar system', Journal of Atmospheric and Oceanic Technology, vol. 15, no. 4, pp. 871-886.
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The development of the first Australian C-band polarimetric/Doppler meteorological radar system (C-POL) is described. Motivated by the need to obtain improved rainfall estimation and the vertical profile of hydrometeors, C-POL was developed jointly by the Bureau of Meteorology (BOM), the Commonwealth Scientific and Industrial Research Organisation of Australia, and the National Center for Atmospheric Research. C-POL is based on a standard operational C-band radar employed by the BOM but modified to be capable of transmitting linear horizontal and vertical polarizations and receiving the co- and cross polarizations on a pulse-to-pulse basis. Standard variables extracted include horizontal reflectivity (ZHH), radial velocity (Vr), spectral width (συ), differential reflectivity (ZDR), differential phase shift (ΦDP), and zero lag correlation coefficient [ρHV(0)]. With the addition of a second receiver chain, the linear depolarization ratio will soon be available. Initial results with the radar are discussed to give examples of the data quality, as well as some of the problems inherent in using a C-band radar in the Tropics.

Saban, D & Braun, RM 1998, 'Multi-carrier direct sequence CDMA in fading situations', Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214), vol. 12, pp. 33-38.
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Saban, G & Braun, RM 1998, 'Wireless local loop and packet radio technology for developing communities', Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214), vol. 75, pp. 1-6.
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Seaman, B & Braun, RM 1998, 'Using cyclostationarity in the modulation classification of analogue signals', Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214), pp. 261-266.
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Tellambura, C, Guo, YJ & Barton, SK 1998, 'Channel estimation using aperiodic binary sequences', IEEE Communications Letters, vol. 2, no. 5, pp. 140-142.
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Estimating a channel impulse response using a known aperiodic sequence is considered. The problem can be reduced to minimizing the trace of the inverse of a Toeplitz matrix. An efficient algorithm for computing this trace is developed and optimal binary sequences up to length 32 are found and tabulated. The use of complementary sequences in this context is also investigated. It is shown that the eigenvalues of the autocorrelation matrices of a pair of complementary sequences sum to a known constant.

Andren, J, Hilding, M & Veitch, D 1970, 'Understanding end-to-end internet traffic dynamics', Global Telecommunications Conference, 1998. GLOBECOM 1998. The Bridge to Global Integration. IEEE, IEEE, pp. 1118-1122.

Banh, BAJ, Anido, GJ & Dutkiewicz, E 1970, 'Handover re-routing schemes for connection oriented services in mobile ATM networks', Proceedings. IEEE INFOCOM '98, the Conference on Computer Communications. Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies. Gateway to the 21st Century (Cat. No.98CH36169), IEEE INFOCOM'98 Conference on Computer Communications Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies Gateway to the 21st Century, IEEE, pp. 1139-1146.
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Wireless ATM (WATM) will be used to support broadband applications for future generation mobile services. To achieve this, the existing ATM protocol must be augmented with mobility management capabilities. One of the important components of mobility management is the ability of the network to seamlessly re-route existing connections to different parts of the network. To date, a number of schemes have been proposed for broadband wireless networks. These schemes can potentially be used in WATM networks. In this paper, we compare the performance of these schemes in terms of their complexity, handover latency, communication disruption period and buffer and bandwidth requirements.

Barattin, M, Cucchiara, R & Piccardi, M 1970, 'A Rule-based Vehicular Traffic Tracking System', Proceedings of the Joint Conference on Information Sciences, pp. 334-337.
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The paper presents a computer vision-based approach to the problem of vehicular traffic monitoring. The approach associates a high-level tracking system to a low-level system that performs moving vehicles detection. The high-level module is based on a large set of rules and is able to keep tracks of all moving or stopped vehicles along the image sequence.

Bird, TS 1970, 'Recent progress in reflector antenna analysis & design', 1998 Symposium on Antenna Technology and Applied Electromagnetics, 1998 Symposium on Antenna Technology and Applied Electromagnetics, IEEE, Ottawa, Canada, pp. 3-6.
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© 1998 IEEE. The latter part of the 20th century has seen significant changes and improvements in the design and practice of reflectorantennas. As well as traditional users of reflectors, such as defence, telecommunication utilities and radio astronomy, significant consumer markets have now opened up. For instance, it is common for many homes and offices to have a dish connected to a wall or roof. At the same time design techniques for reflectors and associated feed systems have also undergone change. Until a few years ago effectsthat were poorly modelled or completely ignored that can now be analysed include, reflectoredge diffraction, near-field effects, grid, composite and painted surfaces, accurate feed models, mutual coupling and scattering in feed arrays, and reflector/feedinteractions. Shaped reflectors are now widely used on satellite antennas, and dielectric-loaded horns are replacing corrugated horns in some earth station applications. It is the purpose here to outline some recent changes and improvements in the design and synthesis techniques used for reflectors and feeds.

Cheng, L, Guo, YJ & Xiao, K 1970, 'Reliability evaluation of composite systems considering voltage stability problems', POWERCON '98: 1998 INTERNATIONAL CONFERENCE ON POWER SYSTEM TECHNOLOGY - PROCEEDINGS, VOLS 1 AND 2, 1998 International Conference on Power System Technology (POWERCON 98), IEEE, PEOPLES R CHINA, BEIJING, pp. 1489-1493.

Cucchiara, R & Piccardi, M 1970, 'Exploiting image processing locality in cache pre-fetching', Proceedings. Fifth International Conference on High Performance Computing (Cat. No. 98EX238), Proceedings. Fifth International Conference on High Performance Computing, IEEE Comput. Soc, CHENNAI, INDIA, pp. 466-472.
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Huang, XJ & Chen, HB 1970, 'Least-squares deconvolution of the mixed-phase unknown pulse', 1988 Seg Annual Meeting, pp. 734-737.
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The conventional least-square deconvolution technique is valid only when the conditions of a minimum-phase wavelet and a white reflectivity series are salisfied. When the wavelet is a mixed-phase pulse, however, the least-squares approach requires that the wavelet is known. In this paper a new least-squares deconvolution method suitable for mixed-phase unknown pulse is proposed. It is shown that one only has to loughly estimate the duration of the mixed-phase unknown wavelet before applying this deconvolution method to the seismic trace which is the convolution of the subierrain reflectivity series and mixedphase pulse wavelet. Tests on some synthetic data show that this method works satisfactorily and is insensitive to the preeslimated wavelet duration. It is also proved that the least-squares deconvolution for mixed-phase unknown pulse is equivalent to a gapped smoothing error filtering which can be decomposed into a forward multi-step prediction error filtering plus a backward multi-step prediction error filtering. It is believed that the new deconvolution technique will find practical applications in the geophysical data processing commercial use.

Liu, RP, Richards, A & Rogers, G 1970, 'MARSHNet, a superimposed QoS guaranteed virtual path network', IEEE GLOBECOM 1998 (Cat. NO. 98CH36250), IEEE GLOBECOM 1998, IEEE, SYDNEY, AUSTRALIA, pp. 7-12.
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This paper describes the design and configuration of a metropolitan ATM network consisting of two superimposed virtual networks. Virtual paths and virtual switches were created to construct the two Virtual Path Networks (VPNs). Creative ideas and novel techniques were employed for network partitioning, bandwidth sharing and QoS guarantees. These techniques did allow most of the design objectives to be met.

Roughan, M, Veitch, D & Rumsewicz, M 1970, 'Computing queue-length distributions for power-law queues', Proceedings. IEEE INFOCOM '98, the Conference on Computer Communications. Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies. Gateway to the 21st Century (Cat. No.98CH36169), IEEE INFOCOM'98 Conference on Computer Communications Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies Gateway to the 21st Century, IEEE, IEEE, pp. 356-363.
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Roughan, M, Veitch, D, Abry, P, IEEE & IEEE 1970, 'On-line estimation of the parameters of long-range dependence', GLOBECOM 98: IEEE GLOBECOM 1998 - CONFERENCE RECORD, VOLS 1-6, IEEE Global Telecommunications Conference (GLOBECOM 98), IEEE, SYDNEY, AUSTRALIA, pp. 3716-3721.