Electrical and Electronic Engineering - Theses
Permanent URI for this collection
Search Results
1 - 7 of 7
-
ItemResource allocation for multiuser OFDM systems(University of Melbourne, 2006)
-
ItemPerformance evaluation and enhancement of mobile and sensor networks( 2006)This thesis addresses the performance evaluation and enhancement of wireless networks. Part I investigates the problem of resource allocation in cellular networks, focusing on handoff, and Part II investigates resource allocation in sensor networks focusing on power management. (For complete abstract open document)
-
ItemResource allocation in OFDM cellular networks( 2006-12)The efficient use of radio resources is crucial in order for future wireless systems to be able to meet the demand for high speed data communication services. Orthogonal Frequency Division Multiplexing (OFDM) is an important technology for future wireless systems as it offers numerous advantages over other existing technologies, such as robust performance over multipath fading channels and the ability to achieve high spectral efficiency. Dynamic resource allocation can fully exploit the advantages of OFDM, especially in multiple user systems. In this thesis, we investigate a resource allocation problem in a multiple user, multiple cell OFDM cellular network focusing on downlink communications. (For complete abstract open document)
-
ItemSignal processing for optical performance monitoring and impairment mitigation( 2006)Optical performance monitoring is essential for managing optical networks. One important quantity to monitor is the optical signal-to-noise ratio (OSNR). And in high bit rate fiber optical systems operating at 10 Gb/s or beyond, compensating optical impairments becomes important. In this thesis, we investigate OSNR monitoring using beat noise and present two new OSNR monitoring techniques. We propose an OSNR monitoring technique using uncorrelated beat noise and show by experiment for a 10 Gb/s system that in the OSNR range from 10 dB to 30 dB, the proposed OSNR monitoring scheme has a measurement error of less than 0.5 dB. Then, we propose and experimentally demonstrate for the first time an OSNR monitoring technique using beat noise for optical packet switched networks which performs monitoring on a packet basis. The response time of the OSNR monitor can be around 10 ns and the OSNR measurement error is found to be less than 0.6 dB for OSNR from 10 dB to 30 dB. We also explore chromatic dispersion and polarization-mode dispersion (PMD) mitigation using Viterbi equalization in 10 Gb/s nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and differential quadrature phase-shift keying (NRZ-DQPSK) systems. We show through simulations that using Viterbi equalizers improves the performance of NRZ-OOK, NRZ-DPSK and NRZ-DQPSK receivers. For NRZ-DQPSK receiver with a Viterbi equalizer, the chromatic dispersion tolerance is about 5048 ps/nm and the PMD tolerance is about 160 ps at 3 dB OSNR penalty.
-
ItemDesign and training of support vector machines( 2006)In this thesis I introduce a new and novel form of SVM known as regression with inequalities, in addition to the standard SVM formulations of binary classification and regression. This extension encompasses both binary classification and regression, reducing the workload when extending the general form; and also provides theoretical insight into the underlying connections between the two formulations.
-
ItemA game theoretic analysis of adaptive radar jamming( 2006-10)Advances in digital signal processing (DSP) and computing technology have resulted in the emergence of increasingly adaptive radar systems. It is clear that the Electronic Attack (EA), or jamming, of such radar systems is expected to become a more difficult task. The reason for this research was to address the issue of jamming adaptive radar systems. This required consideration of adaptive jamming systems and the development of a methodology for outlining the features of such a system is proposed as the key contribution of this thesis. For the first time, game-based optimization methods have been applied to a maritime counter-surveillance/counter-targeting scenario involving conventional, as well as so-called ‘smart’ noise jamming.Conventional noise jamming methods feature prominently in the origins of radar electronic warfare, and are still widely implemented. They have been well studied, and are important for comparisons with coherent jamming techniques.Moreover, noise jamming is more readily applied with limited information support and is therefore germane to the problem of jamming adaptive radars; during theearly stages when the jammer tries to learn about the radar’s parameters and its own optimal actions.A radar and a jammer were considered as informed opponents ‘playing’ in a non-cooperative two-player, zero-sum game. The effects of jamming on the target detection performance of a radar using Constant False Alarm Rate (CFAR)processing were analyzed using a game theoretic approach for three cases: (1) Ungated Range Noise (URN), (2) Range-Gated Noise (RGN) and (3) False-Target (FT) jamming.Assuming a Swerling type II target in the presence of Rayleigh-distributed clutter, utility functions were described for Cell-Averaging (CA) and Order Statistic (OS) CFAR processors and the three cases of jamming. The analyses included optimizations of these utility functions, subject to certain constraints, with respectto control variables (strategies) in the ja
-
ItemArchitectures and technologies for wavelength division multiplexed access networks( 2006-06)Optical fibre communication is very much preferred for the communication of signals over bandwidth of a gigabits per second over distances more than hundreds of kilometres. For a long period of time optical fibre communication has been about how to provide higher bandwidths with reduced cost per bit transmitted. However, this trend has changed from optical transmission to optical networking. By exploiting the wavelength division multiplexing (WDM) technology, optical networks have expanded from backbone networks to metropolitan and access networks to deliver high bandwidth services to the users in a seamless fashion with reduced cost. The ultimate evolution of the optical access network involves fibre-to-the-home (FTTH) technologies, which can potentially offer every kind of information and communication related services. Out of all FTTH technologies, the passive optical network (PON) can potentially offer the most cost-effective solution as the optical network is shared between a number of end users. PONs have significant advantage over competing access technologies as the fibre infrastructure can be effectively future-proofed for upgrades. A number of demonstrations have been carried out for the cost effective deployment of the PONs. However, as these networks evolve, advanced functionalities have to be added over the existing end to end transmissions between the service providers and end users.