Time filter

Source Type

Al-Qahtani F.S.,RMIT University | Gurung A.K.,RMIT University | Zummo S.A.,King Fahd University of Petroleum and Minerals | Mahmoud S.S.,Future Fibre Technologies Pty. Ltd. | Hussain Z.M.,RMIT University
Wireless Personal Communications | Year: 2011

In this paper we derive closed-form expressions for the single-user adaptive capacity of generalized selection combining (GSC) system, taking into account the effect of imperfect channel estimation at the receiver. The channel considered is a slowly varying spatially independent flat Rayleigh fading channel. The complex channel estimate and the actual channel are modelled as jointly Gaussian random variables with a correlation that depends on the estimation quality. Three adaptive transmission schemes are analyzed: (1) optimal power and rate adaptation; and (2) constant power with optimal rate adaptation, and (3) channel inversion with fixed rate. In addition to deriving an exact expression for the capacity of the aforementioned adaptive schemes, we analyze the impact of channel estimation error on the capacity statistics and the symbol error rate for GSC systems. The capacity statistics derived in this paper are the moment generating function, complementary cumulative distribution function and probability density function for arbitrary number of receive antennas. Moreover, exact closed-form expressions for M-PAM/PSK/QAM employing GSC are derived. As expected, the channel estimation error has a significant impact on the system performance. © 2009 Springer Science+Business Media, LLC.

Koziol B.G.,Victoria University of Melbourne | Koziol B.G.,Future Fibre Technologies Pty. Ltd. | Baxter G.W.,Victoria University of Melbourne | Collins S.F.,Victoria University of Melbourne
Journal of Optics A: Pure and Applied Optics | Year: 2010

Measurements of the temperature and strain responses of fluorescence lifetimes for two transitions in praseodymium-doped silica optical fibres are presented. These properties were found to be similar to those measured for other rare-earth-doped fibres, except for the strain response. In particular, the fluorescence lifetime of the, 3H6 transition (centred on 870nm) exhibited a slight decrease with applied strain, rather than an increase. This has implications for our understanding of how strain in rare-earth-doped optical fibres affects fluorescence properties. © 2010 IOP Publishing Ltd.

Future Fibre Technologies Pty Ltd | Date: 2010-10-13

A modalmetric fibre sensor comprises a multimode sensor fibre (

Mahmoud S.S.,Future Fibre Technologies Pty. Ltd. | Katsifolis J.,Future Fibre Technologies Pty. Ltd.
Proceedings - International Carnahan Conference on Security Technology | Year: 2010

The success of any perimeter intrusion detection system depends on three important performance parameters: the probability of detection (POD), the nuisance alarm rate (NAR), and the false alarm rate (FAR). The most fundamental parameter, POD, is normally related to a number of factors such as the event of interest, the sensitivity of the sensor, the installation quality of the system and the reliability of the sensing equipment. A critical performance parameter of any outdoor perimeter intrusion detection system is its capability of discriminating between intrusion and nuisance events without compromising its sensitivity or POD. In this paper, the performance criteria of a real-time fence-mounted distributed fiber-optic intrusion detection system are discussed. The use of event recognition and classification techniques to maintain high detection rates and minimize alarms caused by nuisance events is presented with a performance analysis for different event classification algorithms. Practical results for the detection of intrusion events and suppression of nuisances are also shown. ©2010 Crown.

Mahmoud S.S.,Future Fibre Technologies Pty. Ltd. | Katsifolis J.,Future Fibre Technologies Pty. Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Discriminating between intrusion and nuisance events without compromising sensitivity is a key performance parameter for any outdoor perimeter intrusion detection system. This is especially the case for intrusion and nuisance events which may have a similar impact on a perimeter fence. In this paper, a robust event classification system using features based on level crossings is presented for the detection and recognition of intrusion and non-intrusion events in an outdoor fence-mounted intrusion detection system for a range of operating environments and fence styles. The proposed classification system is applied to a distributed fiber-optic Mach Zehnder (MZ) mounted on a perimeter fence. It consists of a pre-processing stage employing high resolution time-frequency distribution, a novel event detection and feature extraction scheme based on level crossings, and a classification algorithm using a supervised neural network. Experimental results are presented showing accurate classification of different intrusion and non-intrusion events such as fence-climbing, fence-cutting, stone-throwing and stick-dragging. These results demonstrate the robustness of the proposed algorithm for various types of fence fabric and operating environments. © 2010 SPIE.

Discover hidden collaborations