Developing Assessment Framework for Strategic Transportation Projects in Qatar

This paper presents Transportation Assessment Framework and process for selecting, defining, and naming assessment criteria to be used in transport appraisal. The approach is based on a review of national and international practices in transportation planning and appraisal around the world but is adapted to attend the needs and particularities of the Qatar transportation system, according to Transportation Master Plan for Qatar (TMPQ) vision and objectives. The TMPQ vision is derived from four key strategic themes: development, sustainability, livability and culture. The outcome of the research is a comprehensive list, developed using this framework, of 37 transport assessment criteria encompassing direct project impacts, indirect societal impacts, and environmental impacts. This list can serve as a starting point for planners wishing to conduct appraisal for strategic transport projects. A Cost-Benefit Analysis (CBA) procedure and parameter are also developed as part of TAF for a more detailed assessment of the Preferred Scenario(s), covering the impacts (costs and benefits) which can be quantified and monetized. An Excel-based CBA tool is developed and applied to produce the main economic indicators for the preferred scenario, which form part of the assessment criteria that can be monetized

Surface Wave Transmission Line Theory for Single and Many Wire Systems

Examining cables using many conductor transmission line theory has shed light on the modes supported by various cable types. However, so far the theory disregards the fundamental surface wave mode whose lateral confinement increases with frequency and hence is expected to play an important role in high frequency applications. To address this issue, we propose an extension to the theory which incorporates surface waves on uncoated, cylindrical wires. Crucially, this requires new definitions of the per unit length transmission line parameters which are derived using the single wire surface wave solution. By closely examining a two wire and three wire system, we show that these new parameters can predict surface waves as well as modes found using conventional many conductor transmission line theory. Furthermore, all calculated modes are validated experimentally by diagonalization of a measured channel transfer matrix. Additionally, the theoretically predicted propagation constants for the modes are validated against full numerical simulation for the two wire case and good agreement is observed when proximity effects can be neglected.Comment: 22 pages, 5 Figures, data and supplementary material will be made available at a later stag

Dielectric-induced surface wave radiation loss.

We investigate a model which shows how the introduction of a perturbing dielectric close to an electromagnetic surface wave leads to radiation away from the surface through the dielectric. This resembles a surface waveguide passing through a wall or being deployed underground. Our theory, which is based on the mode-matching technique, allows quantitative determination of losses from a bound surface wave mode up to the point of its complete extinction. For a surface wave supported by a coated, conducting sheet the attenuation due to the perturbing dielectric is calculated for a number of frequencies, permittivities of the perturbation and separations between the sheet and the perturbing dielectric. The accuracy of our results is verified by simulation of the system with a full-wave numerical solution. Finally, we report experimental data of perturbed surface waves on a cable, which are in qualitative agreement with our model

Interaction between surface waves on wire lines.

This paper investigates coupling between electromagnetic surface waves on parallel wires. Finite-element method (FEM)-based and analytic models are developed for single- and double-wire Sommerfeld and Goubau lines. Models are validated via measurements for Goubau lines and a comparison between the analytic and the FEM-based computations for coupled Sommerfeld- and Goubau-type lines is carried out. The measurements and calculations show remarkable agreement. The FEM-based and analytic models match remarkably well too. The results exhibit new favourable effects for surface waves propagation over multiple conductors. The short-range behaviour of the coupled wires and, consequently, the existence of an optimum separation of coupled wires is one of the most significant findings of this paper. We comment on the relevance of our results, particularly in relation to applications of high bandwidth demands and cross-coupling effects

Analytic modelling of a planar Goubau line with circular conductor.

Planar Goubau lines show promise as high frequency, low-loss waveguides on a substrate. However, to date only numerical simulations and experimental measurements have been performed. This paper analytically investigates the surface wave mode propagating along a planar Goubau line consisting of a perfectly conducting circular wire on top of a dielectric substrate of finite thickness but infinite width. An approximate equation for the propagation constant is derived and solved through numerical integration. The dependence of the propagation constant on various system parameters is calculated and the results agree well with full numerical simulations. In addition, the spatial distribution of the longitudinal electric field is reported and excellent agreement with a numerical simulation and previous studies is found. Moreover, validation against experimental phase velocity measurements is also reported. Finally, insights gained from the model are considered for a Goubau line with a rectangular conductor. The analytic model reveals that the propagating mode of a planar Goubau line is hybrid in contrast to the transverse magnetic mode of a classic Goubau line

Expanded constellation mapping for enhanced far-end-cross-talk cancellation in G.fast

We propose the novel concept of Expanded Constellation Mapping (ECM) for maximising the received signal power, while cancelling the Far-End-Cross-Talk (FEXT) in copper based wireline communications. The goal of ECM is to beneficially map the transmitted symbol vector to its expanded constellation set by carefully exploiting the copper channels’ specific characteristics. To elaborate, ECM is comprised of the control entity and of the match entity, where the former determines how ECM would be applied, while the latter searches for the best mapping of the transmitted symbol vector to the expanded constellation set. Our numerical results demonstrate that with the aid of ECM, more than 25 dB power efficiency gain may be achieved over linear vectoring. Similarly, about 20 dB gain may be achieved over nonlinear vectoring. From an implementation point of view, ECM imposes minimal structural changes on G.fast, whilst exhibiting beneficial reconfigurability and compatibility

Experimental Evaluation of Multi-operator RIS-assisted Links in Indoor Environment

In this work, we present reconfigurable intelligent surface (RIS)-assisted optimization of the multiple links in the same indoor environment. Multiple RISs from different operators can co-exists and handle independent robust communication links in the same indoor environment. We investigated the key performance metrics with the help of two simultaneously operating RIS-empowered robust communication links at different center frequencies in the same indoor environment. We found with the help of bit error rate (BER) and error vector magnitude (EVM) measurements that two operators can co-exist in the same RF environment without seriously impacting quality of service of users

Downlink Cell-Free Fixed Wireless Access: Architectures, Physical Realities and Research Opportunities

Recently a new paradigm of wireless access, termed as cell-free massive multiple-input multiple-output (MIMO), has drawn significant research interest. Its primary distinction from conventional massive MIMO aided cellular networks is the ability to eliminate the detrimental inter-cell interference (ICI), or to convert ICI into extra power for the intended signal via a multi-cell cooperation approach originated from network MIMO. However, the information-theoretical limit of cell-free access is achieved at the expense of large network configuration overhead and high MIMO processing complexity. Because of the dynamic nature of wireless channels, the global channel state information (CSI) invoked for network MIMO quickly becomes outdated, leading to performance degradation. This paper focuses on the cell-free implementation of fixed wireless access (FWA), a complementary solution to fibre-to-the-premise (FTTP) where the latter is prohibitively expensive. In particular, we discuss the centralisation architectures and channel characteristics of cellfree FWA, as well as their joint implications on imperfect CSI performance. Moreover, measurement-based offline simulations show that the long coherence time ('quasi-static') assumption of real-world FWA channels is only valid against a completely motionless background, and thus it should not be used in FWA system design or performance analysis. Finally, we present new research opportunities for cell-free FWA in terms of physical infrastructure, data processing as well as machine learning

Next generation wireless networks optimisation over heterogeneous traffic environments

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Next generation wireless networks optimisation over heterogeneous traffic environments

EThOS - Electronic Theses Online ServiceGBUnited Kingdo