Physical Sciences and Mathematics Commons^™

Decision Aided Joint Compensation Of Clipping Noise And Nonlinearity For Mimo-Ofdm Systems, Shouyi Yang, Jiangtao Xi, Xiaomin Mu

Faculty of Informatics - Papers (Archive)

In this paper, we propose a new iterative approach to compensate the nonlinearity and clipping noise in multi-input multi-output orthogonal frequency division multiplexing (MlMO-OFDM) system with nonlinear channel. The proposed approach consists of two stages. Firstly a decision aided method is proposed to eliminate the nonlinearity introduced by high power transmit amplifier (HPA). Then this improved decision observations are employed to achieve the clipping noise compensation. The effectiveness of the proposed approach has been verified by computer simulations.

An Adaptive Scalable Multiuser-Ofdm System For Multimedia Transmission Over Fading Channels, Ahmed Muthana M. Nadhim, Jianhua He, Jiangtao Xi, Zongkai Yang

Faculty of Informatics - Papers (Archive)

In this paper, an adaptive scalable multiuser-OFDM system was proposed for multimedia transmission over fading channels. The proposed adaptive algorithm can adapt according to the channel status information of each user's channel status. This algorithm dynamically changes according to the user's channel changes; this can keep fixed QoS at the physical layer. Another predefined QoS for different sessions and services to be provided for different users. This QoS can be guaranteed by multimedia scalability. Scalability can adapt to the service requirements, in terms of transmission data rate and bandwidth. As a result, a robust multimedia transmission scheme is achieved by …

Signal Processing Methods Implemented In A Novel Fbg Sensing System For Vibration/Dynamic Strain Measurement, Xingyuan Xu, Enbang Li, Jiangtao Xi, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

We have demonstrated a novel Fiber Bragg Grating sensing system based on a Fabry-Perot tunable filter for measuring dynamic processes. This system is very suitable for multipoint vibration or dynamic strain detection. However, in some conditions, the response time of Fabry-Perot tunable filter will influence the sensitivity of the sensor that the sensitivity is not kept constant. Therefore, post-processing for the measured vibration signal is necessary to solve this problem. In this paper, the demodulation technique of this system is briefly described and two signal processing methods are introduced to deal with the measured signal to obtain stable measurement of …

Multi-Frequency And Multiple Phase-Shift Sinusoidal Fringe Projection For 3d Profilometry, Enbang Li, X. Peng, Jiangtao Xi, Joe F. Chicharo, Jianquan Yao, D.W. Zhang

Faculty of Informatics - Papers (Archive)

In this paper, we report on a laser fringe projection set-up, which can generate fringe patterns with multiple frequencies and phase shifts. Stationary fringe patterns with sinusoidal intensity distributions are produced by the interference of two laser beams, which are frequency modulated by a pair of acousto-optic modulators (AOMs). The AOMs are driven by two RF signals with the same frequency but a phase delay between them. By changing the RF frequency and the phase delay, the fringe spatial frequency and phase shift can be electronically controlled, which allows high-speed switching from one frequency or phase to another thus makes …

A Comparative Analysis Of The Use Of The Web For Destination Marketing By Regional Tourism Organisations In Chile And The Asia Pacific, Lois Burgess, Joan Cooper, Narciso Cerpa, Jason P. Sargent

Faculty of Informatics - Papers (Archive)

With reports of travel purchases and reservations being one of the fastest growing segments of the Internet community (eMarketer, 2002), it is no surprise that the number of tourism operators on the Web has increased considerably over the past few years. In recent years, Australia and Chile have developed strong social and economic ties. With the introduction of direct air links between Australia and Chile in July 2002, the number of Australian business people and tourists visiting Chile and neighbouring countries increased significantly. This isn’t surprising considering approximately 35,000 Chileans live in Australia (DFAT, 2005). This paper presents the results …

A Generalized Algorithm For The Generation Of Correlated Rayleigh Fading Envelopes In Wireless Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins, Jennifer R. Seberry

Faculty of Informatics - Papers (Archive)

Although generation of correlated Rayleigh fading envelopes has been intensively considered in the literature, all conventional methods have their own shortcomings, which seriously impede their applicability. In this paper, a very general, straightforward algorithm for the generation of an arbitrary number of Rayleigh envelopes with any desired, equal or unequal power, in wireless channels either with or without Doppler frequency shifts, is proposed. The proposed algorithm can be applied to the case of spatial correlation, such as with multiple antennas in Multiple Input Multiple Output (MIMO) systems, or spectral correlation between the random processes like in Orthogonal Frequency Division …

A Data-Fitting Approach For Displacements And Vibration Measurement Using Self-Mixing Interferometers, Yi Zhang, Jiangtao Xi, Joe F. Chicharo, Yanguang Yu

Faculty of Informatics - Papers (Archive)

This paper presents a signal processing approach for vibration measurement using self-mixing interferometer (SMI). Compared to existing approaches, the proposed approach is able to achieve an accuracy of λ/40 which significantly exceeds the accuracy limit associated with conventional simple SMI systems λ/4.

Web Globalization: A Methodology For Developing Usable Websites For The Global Market, Ghassan Al Qaimari

Faculty of Informatics - Papers (Archive)

In today’s global economy, with the appearance of the Internet and the fast evolution of technology, the frontiers of local markets have been fading and blending with global markets. These markets with no boundaries have lead many companies, organizations, educational institutions, and digital libraries to develop their own websites, and to find ways to make them usable and accessible and their products saleable to customers outside their traditional markets. Going global can help corporations lower the cost of entry to international trade, increase sales, create global demands, and establish a reliable, professional and international image online.

This means that website …

Distributing Network Game Servers For Improved Geographical Scalability, Paul A. Boustead, Farzad Safaei, Jeremy Brun

Faculty of Informatics - Papers (Archive)

World-wide multiplayer games present several scalability challenges for large-scale deployment. In recent years, significant research has been devoted to scaling in terms of number of players so that the same virtual world can accommodate larger number of simultaneous avatars. A possible solution is to use grid computing techniques for distribution of processing over a cluster or a distributed set of servers. Scalability with respect to geographical distribution of players is another challenge. Large geographical distances between players introduces propagation delays which are impossible to avoid. Without proper design, responsiveness of the application to user inputs is degraded even when there …

A Theoretical Justification For Partnerships In Community Technology Centre Projects, William Tibben

Faculty of Informatics - Papers (Archive)

In many Community Technology Centre projects, partnerships are emerging as a fundamentally important aspect to achieving sustainability. While generally considered a less formal approach than direct funding from rich benefactors such as Government or philanthropic organisations, the paper argues that partnerships offer an effective and theoretically justifiable framework to achieving sustainability. Drawing on information based perspectives the paper proposes a theoretical justification for the use of partnerships in community informatics projects that is able to incorporate individuals and groups in the analysis.

A Secure Multicast Architecture And Protocol For Mospf, Junqi Zhang, Yi Mu, Vijay Varadharajan

Faculty of Informatics - Papers (Archive)

Multicast Open Shortest Path First (MOSPF) is an en hancement to unicast routing protocol OSPF. It has been widely used in many multicast applications for years. How ever, its security is still a major concern in some applica tions. Much work has been done on data protection, but only a few works have been done on member access con trol mechanisms. In this paper, we present a new secure multicast architecture and protocol for MOSPF from the perspective of member access control. Our new model in cludes a variant of previous access control mechanism and a novel distributed encryption scheme. …