Enhanced analysis of WCDMA networks with repeaters deployment

This paper addresses the analysis of WCDMA systems with repeaters deployment. A generic and compact expression for up- and downlinks evaluation has been mathematically derived so that transmission powers and other radio resource management parameters can be calculated without simplifications. In particular, the real different path delays, taking into account the repeaters presence and the finite nature of the time window of Rake receivers are considered. This allows an enhanced analysis with respect to classical approaches from a system level viewpoint. Furthermore, higher reliable and accurate predictions on network performance can be obtained, which can be remarkably useful for network planning and management. By using these expressions, relevant network parameters have been evaluated and compared with the ones obtained using the classical approximations. The differences in the obtained metrics are highlighted, putting in evidence the improvement provided by the proposed analysis.Peer Reviewe

Application priority framework for fixed mobile converged communication networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The current prospects in wired and wireless access networks, it is becoming increasingly important to address potential convergence in order to offer integrated broadband services. These systems will need to offer higher data transmission capacities and long battery life, which is the catalyst for an everincreasing variety of air interface technologies targeting local area to wide area connectivity. Current integrated industrial networks do not offer application aware context delivery and enhanced services for optimised networks. Application aware services provide value-added functionality to business applications by capturing, integrating, and consolidating intelligence about users and their endpoint devices from various points in the network. This thesis mainly intends to resolve the issues related to ubiquitous application aware service, fair allocation of radio access, reduced energy consumption and improved capacity. A technique that measures and evaluates the data rate demand to reduce application response time and queuing delay for multi radio interfaces is proposed. The technique overcomes the challenges of network integration, requiring no user intervention, saving battery life and selecting the radio access connection for the application requested by the end user. This study is split in two parts. The first contribution identifies some constraints of the services towards the application layer in terms of e.g. data rate and signal strength. The objectives are achieved by application controlled handover (ACH) mechanism in order to maintain acceptable data rate for real-time application services. It also looks into the impact of the radio link on the application and identifies elements and parameters like wireless link quality and handover that will influence the application type. It also identifies some enhanced traditional mechanisms such as distance controlled multihop and mesh topology required in order to support energy efficient multimedia applications. The second contribution unfolds an intelligent application priority assignment mechanism (IAPAM) for medical applications using wireless sensor networks. IAPAM proposes and evaluates a technique based on prioritising multiple virtual queues for the critical nature of medical data to improve instant transmission. Various mobility patterns (directed, controlled and random waypoint) has been investigated and compared by simulating IAPAM enabled mobile BWSN. The following topics have been studied, modelled, simulated and discussed in this thesis: 1. Application Controlled Handover (ACH) for multi radios over fibre 2. Power Controlled Scheme for mesh multi radios over fibre using ACH 3. IAPAM for Biomedical Wireless Sensor Networks (BWSN) and impact of mobility over IAPAM enabled BWSN. Extensive simulation studies are performed to analyze and to evaluate the proposed techniques. Simulation results demonstrate significant improvements in multi radios over fibre performance in terms of application response delay and power consumption by upto 75% and 15 % respectively, reduction in traffic loss by upto 53% and reduction in delay for real time application by more than 25% in some cases

Optical free space feedforward non-linearity correction system

Recent years have seen unprecedented growth in the popularity and deployment of mobile phones. As this continues, so the strain on existing mobile cellular radio network has also increased, leading to the need to investigate new technologies to relieve this pressure. The problem is being further exacerbated by the introduction of the 3rd generation of mobile communications, otherwise known as UMTS (Universal Mobile Telecommunications System), with the aim of offering multimedia services on pocket sized portable receivers. A major cost of the mobile radio network, in terms of both financial and social/environmental aspects, is the need apparent need for more base transceiver stations (BTS), due to the increased number of services, and the density of them. Therefore, judicious use of fewer, but more "intelligent" base stations, thereby reducing the overall system costs, and extra flexibility in the design of mobile cells would be desirable. This can be achieved by having the BTS antennas remotely positioned from the BTS by transmitting the radio signals down an optical fibre or, as in this project, over free space. The main application for this is in densely urban heavy use areas, where there is extensive reuse of both cell and cell cluster. This, along with building shadowing, would require a BTS on every corner, and where extra cell design flexibility would be desirable. Also, in remote rural areas, where various natural features, such as rivers or mountains can cause similar cell design problems, there is a need for this flexibility. The problem with this requirement is that the electrical to optical conversion process, involving a laser diode driver unit, is inherently non-linear, and, unless this is resolved, the desired signal will become unusable due to distortion. To overcome these nonlinearities, a novel correction may be used, based on an optical feedforward correction technique. The prototype system employs off-the-shelf components, and has one Fabry Perot laser diode (FP-LD) providing two signals (via a beam splitter), for a main path and one for the error path loop. The error path signal is detected by a receiver circuit, then mixed with a reference signal to produce a 'pure' error signal, which then modulates the second FP-LD. In contrast with previous fibre feedforward systems, where the two LD outputs are then combined in the optical fibre pre-reception, this system has to combine the signals post-reception. After the main signal and error signal are received and recombined, the non-linearities of the main path are predominantly cancelled by those present in the error path signal, leaving only the desired signal, free of non-linearities

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Optical free space feedforward non-linearity correction system

Recent years have seen unprecedented growth in the popularity and deployment of mobile phones. As this continues, so the strain on existing mobile cellular radio network has also increased, leading to the need to investigate new technologies to relieve this pressure. The problem is being further exacerbated by the introduction of the 3rd generation of mobile communications, otherwise known as UMTS (Universal Mobile Telecommunications System), with the aim of offering multimedia services on pocket sized portable receivers. A major cost of the mobile radio network, in terms of both financial and social/environmental aspects, is the need apparent need for more base transceiver stations (BTS), due to the increased number of services, and the density of them. Therefore, judicious use of fewer, but more "intelligent" base stations, thereby reducing the overall system costs, and extra flexibility in the design of mobile cells would be desirable. This can be achieved by having the BTS antennas remotely positioned from the BTS by transmitting the radio signals down an optical fibre or, as in this project, over free space. The main application for this is in densely urban heavy use areas, where there is extensive reuse of both cell and cell cluster. This, along with building shadowing, would require a BTS on every corner, and where extra cell design flexibility would be desirable. Also, in remote rural areas, where various natural features, such as rivers or mountains can cause similar cell design problems, there is a need for this flexibility. The problem with this requirement is that the electrical to optical conversion process, involving a laser diode driver unit, is inherently non-linear, and, unless this is resolved, the desired signal will become unusable due to distortion. To overcome these nonlinearities, a novel correction may be used, based on an optical feedforward correction technique. The prototype system employs off-the-shelf components, and has one Fabry Perot laser diode (FP-LD) providing two signals (via a beam splitter), for a main path and one for the error path loop. The error path signal is detected by a receiver circuit, then mixed with a reference signal to produce a 'pure' error signal, which then modulates the second FP-LD. In contrast with previous fibre feedforward systems, where the two LD outputs are then combined in the optical fibre pre-reception, this system has to combine the signals post-reception. After the main signal and error signal are received and recombined, the non-linearities of the main path are predominantly cancelled by those present in the error path signal, leaving only the desired signal, free of non-linearities.EThOS - Electronic Theses Online ServiceEngineering and Physical Sciences Research Council (Great Britain) (EPSRC)GBUnited Kingdo

Advanced Trends in Wireless Communications

Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics