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 & 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.

Bateman, DG, Bird, TS & Mohan, AS 1998, 'Asymptotic approximation of some integrals involved in EFIE solutions using the method of moments', IEE Proceedings - Microwaves, Antennas and Propagation, vol. 145, no. 4, pp. 361-361.
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It is well known that, in electromagnetic-field analysis using the method of moments, the matrix-filling time can dominate the total solution time. Therefore, having an efficient means of calculating the elements of the matrix is important. Asymptotic an

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), 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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Parfitt, AJ & Bird, TS 1998, 'Computation of aperture antenna mutual coupling using FDTD and Kirchhoff field transformation', Electronics Letters, vol. 34, no. 12, pp. 1167-1167.
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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), 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), 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.

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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Guo, YJ, Vadgama, S, Davies, M, Khalab, J, Zarri, M & Spink, D 1970, 'Adaptive antenna for CDMA', IEEE International Symposium on Spread Spectrum Techniques & Applications, pp. 590-594.
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A decision directed adaptive antenna array for the uplink of CDMA cellular systems, which is based on a normalized least mean square algorithm (NLMS), is presented. The bit error ratio performance of the adaptive antenna in various scenarios, which include the use of transmission power control (TPC) and diversity combining, is studied. It is shown that the adaptive antenna outperforms the steering beam technique when the signal-to-noise ratio is large and the active users are clustered. However, the performance of the adaptive antenna becomes very similar to that of the steering beam when there are a large number of randomly distributed active users in the sector.

Liu, RP, Richards, A & Rogers, G 1970, 'MARSHNet, a superimposed QoS guaranteed virtual path network', Conference Record / IEEE Global Telecommunications Conference, IEEE Global Telecommunications Conference (GLOBECOM 98), 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.

Parfitt, AJ & Bird, TS 1970, 'Application of a near-field transform algorithm to antenna coupling using the FDTD method', IEEE Antennas and Propagation Society International Symposium. 1998 Digest. Antennas: Gateways to the Global Network. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.98CH36194), IEEE Antennas and Propagation Society International Symposium. 1998 Digest. Antennas: Gateways to the Global Network. Held in conjunction with: USNC/URSI National Radio Science Meeting, IEEE, pp. 500-503.
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© 1998 IEEE. The finite-difference time-domain (FDTD) method is useful in many antenna applications because it facilitates modelling of complex structures and is capable of characterising antenna performance over a wide-frequency band. However, for antenna arrays of even modest size, the excessive computer storage and run-time may become prohibitive for design and optimisation purposes. Some work has been done with time-domain transform methods for computing weak coupling between antennas (Page et al. 1996). In this paper, an algorithm is developed using the Kirchhoff near-field to near-field transformation (Shlager and Smith, 1995) for the one-way coupling between antenna elements. This coupling representation is then applied to arrays in a manner analogous to an element-by-element analysis in the frequency domain, except that in the method described here the coupled currents at the antenna-feed ports are added in the time-domain so as to permit the introduction of true-time delays for wide-band beam steering. The advantages of the transform method over a full FDTD method are smaller computer storage and a reduction in late-time FDTD effects associated with reflections from the absorbing boundary on the outer surface of the computational domain and also from numerical dispersion and instabilities.

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.

Tellambura, C, Parker, MG & Barton, SK 1970, 'Channel estimation using discrete Fourier transform techniques', GLOBECOM 98: IEEE GLOBECOM 1998 - CONFERENCE RECORD, VOLS 1-6, IEEE Global Telecommunications Conference (GLOBECOM 98), IEEE, SYDNEY, AUSTRALIA, pp. 148-152.