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Title: Stochastic propagation and planning models for broadband fixed wireless access links
Author: Muhi-Eldeen, Zaid M. H.
ISNI:       0000 0001 3428 9613
Awarding Body: University of Glamorgan
Current Institution: University of South Wales
Date of Award: 2008
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Due to the rapid progress in wireless communication technologies and the increasing demands for new services; cutting edge techniques and research have developed wireless access delivery of broadband data. Such systems referred to as Broadband Fixed Wireless Access Systems (BFWA) or alternatively, Local Multipoint Distribution Systems (LMDS), are increasingly being regarded as a legitimate challenger to cable and digital subscriber lines (DSL), particularly in markets with poor cable or copper infrastructure. These systems have capabilities that go beyond the current WiFi and WiMAX technologies by providing users with higher bandwidths and faster data rates. The frequency of operation for such networks lies between 28 and 42 GHz according to the spectrum bands allocated for future LMDS networks. The presented work aims at proposing a generalized stochastic model for the LMDS urban/suburban propagation channel. The model is based on a physical electromagnetic representation of the millimetre wavelength channel, with particular emphasis on fading margins in line-of-sight (LOS) links. The study focuses on the analysis, modelling and measurements ofthe fading effects ofsignal scattering caused by building surfaces and the ground on the direct field in an LMDS link at millimetrewaves. Outcomes have been validated against experimental results obtained in realistic propagation scenarios. More than 180 field measurement sets were taken at 40 GHz for model testing and validation purposes. The main innovation of this work is the solution proposed to address the problem of signal scatter at millimetre-wave lengths. The approach uses high-frequency approximations to the analytical solution given by Kirchhoffs tangent-plane representation of rough surfaces. The electromagnetic field and signal power at the receiver a~e considered random and are evaluated using the Physical Optics method over different possible realizations of the surface geometry and building architectural features. This has resulted in novel derivations ~f the mean field, mean power density and scatter distribution of the scattered field. In comparison to deterministic models, such as ray-tracing that require intensive computations and detailed millimetric resolution knowledge of topographical data that are almost impossible to obtain, the proposed model is rather efficient and yields accurate results. The model has also been employed in analysing the effects of building scatter on the variance of the main desired link and the adjacent- or co-channel interfering link. arising from neighbouring cells in cellular LMDS networks. This has enabled predictions of signal-to-interference ratio statistics and distributions for a particular underlyin~ propagation environment. Overall, comparisons yielded very good agreements between measurements and predictions of the main statistical parameters, thus verifying the main assumptions relating to the received signal strength, as well as the validity of a Rician distribution in describing the signal envelope variability for both the main and interference links in complex millimetre-wave propagation environments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available