Search results

The purpose of this study is to understand the effects of building components of a growing concrete structure and different building materials such as glass and steel on Wi-Fi signals propagation in a construction site. Wireless local area networks are considered effective tools to link the islands-of-communication in construction. Still, designing a Wi-Fi network that can grow with a new construction requires that one understands the performance of propagation of electromagnetic signals transmitted at 2.4 GHz.

This paper reviews the theoretical behavior of electromagnetic signals when signal attenuation is caused by various construction materials changing their strengths, directions and possibly leading to total absorption. The authors used a typical building layout to conduct experimental work to measure the effect of common building features and communication technologies on signal strengths.

The measured data not only confirmed the theory-based predictions but also demonstrated the complexity of predicting signal propagation when obstructions inhibit the line-of-sight “travel” of electromagnetic signals.

Different to other papers, the experiments were conducted outside a concrete building mimicking the situation where the transmitter is set up at the site office.

This paper aims to present the design and implementation of a circularly polarized co-planar waveguide (CPW) fed wideband pie-shaped monopole antenna for multi-antenna techniques. Multi-antenna techniques are promising solutions for higher data rate and enhanced reliability of wireless applications. They find numerous applications in 4G/5G networks and in most wireless standards such as wireless local area networks (WLAN), wireless fidelity and worldwide interoperability for microwave access systems to enhance the channel capacity without additional spectrum by means of multi-path propagation techniques.

The antenna is designed to operate at three WLAN frequency bands of 4.8, 5.2 and 5.8 GHz. The measured 10 dB impedance bandwidth of the proposed antenna element is 1.2 GHz (24.23 per cent). The proposed CPW fed, pie-shaped monopole antenna has a gain of 5.4 dB and an efficiency of 72.8 per cent at 4.8 GHz.

To use the proposed antenna in a multi-antenna environment, the antennas have to be placed in a close proximity to each other. The close proximity introduces strong mutual coupling between the antennas, which in turn degrades the performance of multi-antenna systems. A multi-antenna system with two antenna elements has been constructed with an edge to edge spacing of 0.24 λ₀ (15 mm), and the mutual coupling level is −17 dB. To enhance the isolation between the antenna elements, a shorting pin-based interconnected semicircles enclosed decoupling structure is proposed, which improves the isolation by a factor of 12.67 dB at 4.8 GHz.

To validate the performance of the proposed multi-antenna in working environment, the performance metrics such as envelope correlation coefficient (ECC), diversity gain (DG) and total active reflection coefficient (TARC) are computed for the proposed multiple-input multiple-output (MIMO) antenna. The ECC value is 0.000366 at center frequency and below 0.09 for the entire operating bandwidth, which is well below the acceptable level of 0.5 as per 3GPP standard. The DG value lies above 9.5 dB for the entire operating bandwidths and it is well above the minimum value of 3 dB. The TARC values are calculated based on S parameters, and it proves that the proposed antenna a good candidate for the multi-antenna systems.

Collecting and analysing data on mobile service usage is increasingly complex as usage diverges between different types of devices and networks. The purpose of this paper is to suggest and apply a holistic framework that helps in designing mobile service usage research as well as in communicating, positioning, and comparing research results.

The framework was constructed based on longitudinal and cross‐sectional mobile service usage measurements carried out in Finland annually in 2005‐2008, covering 80‐90 percent of all mobile users and service usage. Broad use of multiple data collection methods and measurement points enabled data and method triangulation, as well as analysis and comparison of their scopes and limitations.

The paper suggests a holistic framework for analysing mobile services, relying on service science approach. For measurements and analysis, mobile services are decomposed into four technical components: devices, applications, networks, and content. The paper further presents classifications for each component and discusses their relationships with possible measurement points. The framework is applied to mobile browsing usage studies.

Future work includes adding an actors dimension to the framework in order to analyse their roles in the value networks providing mobile services. Extending the framework to Internet services more generally is also possible.

The paper presents an original, broadly applicable framework for designing mobile service usage research, and communicating, positioning, and comparing research results. The framework helps academics and practitioners to design and to recognise the limitations of mobile service usage studies, and to avoid misinterpretations based on insufficient data.

The purpose of this paper is to develop a model for the use of mobile computing in the management of on‐site construction information and communication.

The research strategy contains three steps: a pilot study for the first stage, a survey that investigated the information needs of particular users and the nature of on‐site information, and finally the development of a model and the validation and evaluation by operational scenarios.

The developed model explores how mobile computing can be used on construction sites to manage on‐site information. This model, firstly, identifies the key factors of mobile computer, wireless network, mobile application, construction personnel, construction information, and construction site; secondly it describes the relationships and interactions among these factors. Based on the model, the selection process for mobile computing strategy includes the clarification of information management process, the creations of overview for mobile computing solution, the identification of mobile computing strategy, and the selection of appropriate mobile computing technology.

The developed model explores the general concepts and the internal relationships at the two areas of mobile computing and construction site information management. The application of the model can help users to select mobile computing strategies for managing on‐site construction information based on the characteristics of their projects.

Wireless mesh networks (WMNs) have evolved quickly during the last several years. They are widely used in a lot of fields. Channel allocation provides basic means to guarantee mesh networks’ good performance such as efficient routing. The purpose of this paper is to study channel allocation in mesh networks.

First, the papers in channel allocation fields are surveyed, and then the limitations in existing methods noted. Graph theory is used to find a better model to represent the problem and algorithms are proposed based on this model. Simulation proved that algorithms are better than the previous conflict graph‐based approaches.

The paper analyzes the conflict graph‐based model and finds its limitations, then proposes a bipartite graph‐based model. Algorithms were devised based on this model. Simulation results illustrate that the algorithms can reduce the starvation ratio and improve the bandwidth utilization, compared with previous conflict graph‐based algorithms.

The research of this paper is based on an ideal network environment without interference or noises. It will be better if the noises are considered in future work.

To study the routing strategies of WMNs, it is not sufficient to only consider path length as routing metric since the nodes are heterogeneous. The routing metrics should include the channel bandwidths which are the results of channel allocation.

This paper presents a new bipartite graph‐based model to represent the channel allocation problem in mesh networks. This model is more efficient and includes more information compared with conflict graph model, and it also proposes channel allocation algorithms based on bipartite graph‐based model. The algorithms can reduce starvation ratio and improve the bandwidth utilization.

Global commerce demands flexibility in when and how work gets done, as modern businesses increasingly require real‐time responses to partners and customers. With low costs, companies look to mobility as a way to speed responsiveness and increase the personalization of customer service offerings. Mobility is a key element of networking allowing enterprises to unlock their business process from fixed points. A unified approach to enterprise mobility delivers integrated wired/wireless networking, mobile extensions to unified communications, geographic, and end‐point independent network access and location services as major architectural components. As a consequence, this paper aims to focus on a converged architecture that spans wired and wireless networks to enable a seamless delivery of integrated services across the enterprise.

This paper builds a framework to facilitate a continuous delivery of voice services. It also examines an architecture that traverses wireless local area network and local area network. And, proposes a mathematical model of the services delivery in order to analyze network behavior as a response to the new services introducing.

The authors constructed a service scenario framework and also put forward an analytical model of the services delivery for analyzing network behavior response for the inclusion of new services. They also evaluated a network infrastructure, services, and applications, including the prospective converged services, as well as the technology for the transition to future services.

This paper contributes to the development of seamless services delivery model for providing enhanced business services to the enterprise customers along with the ability to migrate more tightly.

This paper investigates the main trends and uncertainties that will define fourth generation mobile systems and services (4G) in Europe. It outlines two divergent visions on 4G: the so‐called “immediate” 4G vision, consisting of wireless local area networks (WLANs) combined with other wireless access technologies, competing with 3G in the short term, and the so‐called “linear” 4G vision, in which the 3G standard is not replaced until the end of its life cycle by an ultra‐high speed broadband wireless network. Which of these visions will materialise, and what this means for the competitiveness of the main 4G stakeholders in Europe, will be to a large extent determined by which business models are feasible for 4G.

Using a brief history of the development of WLAN standards and products this paper seeks to explain how unlicensed spectrum regulations by the Federal Communications Commission (FCC) have affected the industry.

The paper's approach is one of personal experience.

In general, the FCC's initiative to create an “unlicensed commons” for various forms of wireless communication applications has been the key enabler of today's multi‐billion dollar per year WLAN industry. In particular, certain regulatory decisions over the past 25 years regarding these bands have had profound, generally beneficial but sometimes unexpected influence on the WLAN industry.

The paper attempts to document these inflection points and their impacts on WLANs as well as to provide some insight as to how future evolutions of the unlicensed spectrum regulations can best enable optimal usage of this valuable spectrum.

The paper aims to propose an optimized handover necessity estimation scheme for a mobile terminal (MT) traversing from a third-generation (3G) cellular network into the wireless local area network (WLAN) cell for reducing the number of handover failures and unnecessary handovers.

The proposed optimized handover necessity estimation scheme comprises of two algorithms – a “travelling time prediction” reliant on consecutive received signal strength (RSS) measurements and MT’s velocity, and a “time threshold estimation” depending on the handover latency, WLAN’s cell radius, tolerable handover failure probability and the tolerable unnecessary handover probability.

Our performance analysis reveals that the suggested mechanism effectively minimizes the number of handover failures and unnecessary handovers by 60 per cent as compared to the already proposed schemes in the literature.

The convergence of Internet and wireless mobile communication accompanied by a massive increase in the number of cellular subscribers has led mobility management to emerge as a significant and challenging domain for wireless mobile communication over the Internet. Mobility management enables serving networks to locate roaming terminals for the call delivery (location management) and ensures a seamless connection as MT enters into the new service area (handover management). In this manuscript, an optimized handover necessity estimation scheme has been envisaged for reducing the probability of handover failures and unnecessary handovers from 3G cellular networks to WLANs to provide optimal network utilization along with an enhanced user satisfaction. Performance analysis reveals that the suggested scheme yields enhanced results as compared to the schemes already proposed in the literature.

Wireless LANs (WLAN) offer network flexibility and end‐user mobility, making them one of the hottest technologies today. They have great impact on individuals and organizations. Now people can use wireless networks in every application where recent findings indicate that growth in WLAN market continues to be driven by the corporate and educational sectors, where the desire to increase productivity and the benefit of enhanced mobility and learning outcomes continue to fuel demand. A questionnaire was developed to survey the behavior of end‐users, especially students and faculty, in using wireless laptops in accessing information from the Internet, digital libraries and many electronic sources in their education and research. The paper presents the advantages and disadvantages of using wireless network laptops as well as barriers for not using them in Higher Education. Special new update on wireless network security will be included. Guidelines for implementing wireless laptops in higher education are discussed.