The theoretical advantages of ground-satellite optical communication systems can only be exploited, if means can be found to circumvent the limitations due to atmospheric effects. Atmospheric turbulence dominates the analysis and design of these links. The effects of atmospheric turbulence on the performance of ground-satellite optical communication systems and possible countermeasures are investigated in this thesis. The design and analysis of any optical system operating in the atmosphere requires empirical investigations of atmospheric turbulence conditions at the system's location. Stellar observations provide a useful and convenient means for this purpose in the case of ground-satellite optical communications. The available techniques are reviewed. The experimental setup for a particular technique is described and initial results are presented. We were involved in the first ever ground-satellite optical communication experiments conducted between Japanese Engineering Test Satellite VI and a ground station in Tokyo. One issue which has not yet been satisfactorily resolved is the probability density function (PDF) of intensity fluctuations. It was theoretically shown that the PDF approaches a negative exponential in the very strong turbulence region. Experimental evidence is presented in support of this prediction. The ETS-VI experiment results also confirm that too large a beam size can have significantly deleterious effects on fading performance. Early analyses predicted drastic reductions in uplink on-axis scintillation variance with increasing beam size. As the beam size is increased, the scintillation variance gradient off the beam centre becomes large, and eventually the limitation of the first-order theory is exceeded. An explicit limit on the beam size is identified in this thesis: the beam radius must not exceed a third of the coherence scale. Analyses also predict that appropriately converging the beam results in less scintillation compared to a collimated beam. During the ETS-VI experiment we were not able confirm this prediction. Supplements to the first-order theory also suggest that converging beams behave very similarly to collimated beams. This makes the uplink beam size the single most important adjustable parameter. Possible countermeasures to the atmospheric turbulence effects are identified and reviewed separately for the downlink and the uplink. It is emphasized that uplink transmitter beam size is a crucial design parameter and its optimum value changes continuously according to changing turbulence conditions along the propagation path. A previous study concluded that the optimum beam size is of the order of the coherence scale. It is shown that the optimum size is critically dependent on beam wander and pointing accuracy, and can in fact be much smaller. A novel countermeasure is proposed in which the uplink transmitter beam size is controlled in real time in response to measured turbulence parameters to maximize mean intensity and minimize fluctuations at the satellite receiver.

In this study, a novel multi-parameter overall situation optimisation method and mathematical model has been developed for use with terrestrial and space reflector antenna electro-mechanical systems and other metallic and polymer composite civil engineering structures. To satisfy extremely high design requirements, the proposed approach incorporates the objectives from various structural and electromagnetic (EM) performances of the system such as structural frequency, weight, stiffness, strength, reflector surface accuracy, antenna EM efficiency (gain), and radiation patterns at many working/loading cases simultaneously. The optimisation involves geometric and material design variables, and integrated design of composites and structural systems. Various terrestrial, launch and orbital working environments and loading cases which affect antenna performances have been included in the optimisation. These involve self-weight at different elevation attitudes, wind loading, random/dynamic loads and temperature distributions. Both truss and sandwich parabolic reflector panels with honeycomb core and carbon fibre laminate skins stiffened with composite ribs have been optimised. The effects of structural deformation on antenna EM performances have been investigated, modelled and repeatedly analysed in the iterative optimum-seeking procedure. Optical ray tracing, spline function aperture field interpolation, geometric optics aperture integration, Zernike modes analysis and FFT techniques have been used to analyse the EM performances of distorted reflector antennas. An important aspect of the work was the establishment of evaluation criteria in optimising engineering systems. A new method is presented, which can be used as a design review tool to assess the design quality of engineering systems. This systematic method quantitatively evaluates a design from multi-discipline and numerous points of view simultaneously for Pareto optimisation. A general purpose optimisation program MOST (Multifactor Optimisation of Structures Technique) has been developed to implement the proposed approach. MOST has the ability to utilise ABAQUS as an analysis routine for linear and non-linear, static and dynamic structural analysis in the optimisation procedures. Examples are presented to demonstrate the capabilities of the optimisation methodology and MOST program system. These examples are: an 8m Cassegrain antenna system, a 3.6x2.6m composite space deployable reflector antenna structure, and two 4m low side-lobe off-set antenna systems (with composite structures). The optimisation results for these antennas show that the optimisation procedures succeed in that at all the working/loading cases the antenna performances have been greatly improved.

Future mobile broadband communication systems aim to provide a wide range of multimedia services (telephony, video conferencing, audio and video broadcasting, etc.) to a large number of users. In order to achieve a global coverage and reach remote users, satellite is foreseen to be a key component in the development of such networks. When compared to first-generation mobile satellite communication systems, these future satellite networks will need to provide significantly higher data rates whilst achieving very low bit error probability values. In order to keep the mobile user terminal as well as on-board processing complexity as low as possible, it is important to reach the required quality of service with very low values of the signal-to-noise ratio. Hence, particular attention must be paid to the design of the air interface of these future satellite systems. The use of CDMA presents a number of advantages for mobile communication systems, and hence CDMA technology has recently received a lot of attention for both second generation and future terrestrial multimedia systems. However, less effort has been put into the design of CDMA solutions for satellite communications. Moreover, good air interface designs for terrestrial systems do not necessarily translate into efficient solutions for the satellite environment. Hence, different techniques aimed at improving the performance of CDMA satellite systems are proposed in this thesis. First, the performance of S-CDMA, which reduces the level of MAI by co-ordinating the transmission of the different users, is analysed in satellite fading channels. Comparisons with the more conventional A-CDMA are provided and the impact on the transmission quality of imperfect power control, synchronisation errors and pulse shaping is assessed. In order to meet the very tight requirements set for multimedia services, FEC coding is required. Hence, the performance of S-CDMA in fading channels is presented for different channel coding techniques. The performance of the different schemes is characterised with both power and spectral efficiency and comparisons are made. In order to reduce the performance degradation due to the MAI, it is also possible to use multiuser detection algorithms at the receiver. In this thesis, the performance of MUD algorithms using an ANN architecture is analysed in satellite fading channels. Different training strategies and algorithms are considered and the performance of the ANN receivers is compared to that of the conventional correlator as well as other MUD algorithms. Finally, a number of different multi-rate spreading techniques are proposed and their respective complexity is discussed and compared. The power fluctuations caused by these different multi-rate spreading techniques are analysed in order to evaluate their performance in the satellite non-linear channel.

The origins of spread spectrum are in navigation and military systems. Techniques originally developed to reduce the effects of the intentional jamming also proved suitable for communications through dispersive channels in cellular applications. In 1949 the first time hoping spread spectrum multiple access system has been introduced by John Pierce. A direct-sequence spread spectrum system has been proposed by De Rosa-Rogoff later in 1950. He has also introduced the concept of processing gain. However the commercialisation of cellular direct-sequence code division multiple access (DS-CDMA) systems became possible only during the 1980's and 1990's. In 2000 and beyond we will be witness to the standardisation and commercialisation of wide band CDMA system with a bandwidth of 5 MHz or more. While CDMA presents a number of advantages for cellular mobile communications, it has its own drawbacks. Good air interface designs provide efficient solutions for the terrestrial cellular system. We first take a look at the problem of narrow-band and partial band interference suppression in a CDMA system. By using Poor's model for partial-band interference, some interference suppression techniques are analysed. Then the concept of hybrid genetic prediction is introduced which outperforms the nonlinear techniques in terms of SNR improvements. The performance of a CDMA system can be degraded by Multiple Access Interference (MAI) due to the presence of many users in the same bandwidth. After analysing the structure and performance of existing multi user detection techniques, a low complexity bit level detector is proposed to reduce MAI in synchronous CDMA (S-CDMA) system for an AWGN channel. It is shown how it is possible to reach almost the single user bound by combining detection theory and the fundamentals laws of evolution found in nature. Nonlinear mappings are added to the proposed detector to increase detector's performance by reducing the misleading effect of noise on the detection process. Then for Asynchronous CDMA (A-CDMA), a novel packet level genetic detector is proposed. The near-far resistance feature of the proposed detector is studied. The effect of different parameters of genetic engine i.e. chromosome length, gene's value or mutation and crossover probabilities on its performance are characterised. Different initialisation methods are introduced. For high bit rate CDMA system in multimedia applications in a dispersive CDMA channel, Inter Symbol Interference (ISI) becomes another highly important factor that degrades system performance. It is shown how it is possible to use a signal sub-space based detector as a core detector for a hybrid genetic Multi user detector.

The aim of this research is to enhance the quality of service in video applications when they are operating over error prone environments. With high compression ratio and low complexity block transform video coders, such as ITU-T H.263 standard algorithm for very low bit rate video coding, compressed video streams can be used for multimedia services. However, when transmitting compressed video streams over channels with degraded conditions, several problems arise and undermine the video decoder from correctly reconstructing the video signal. This thesis presents several techniques employed to enhance the quality of service of a video communication application under erroneous conditions. First, block transform methods for video coding are examined, and their strengths and weaknesses are assessed in terms of performance and error robustness. Packetised video signals are considered and two different techniques are implemented for packet video networks to improve the quality of service on one hand and help resolve the state of congestion that might occur on any video communication medium on the other hand. Additionally, zero redundancy error concealment techniques are considered and applied on the block based video decoder to improve the quality of the reconstructed video signal without any redundancy added on the video bitstream. Then, the aspects of error resilience issues in block transfom video coders are discussed. Based on the different categories of errors encountered in coded video streams, several novel techniques are implemented to render the video coder more immune to channel deterioration. Some of these techniques are combined to form an error resilience algorithm that is implemented on H.263 to enhance its performance over error prone environments such as mobile radio links. In parallel with the development process of the MPEG-4 video coder, we apply the two-way decoding with reversible codewords on the H.263 standard. Results are shown throughout the thesis to evidence the effectiveness of the proposed techniques and illustrate the improvement on the quality of service on both the objective and subjective scales. We conclude with thoughts for future expansion of error control strategies in block based video coding for mobile multimedia services over the foreseen universal mobile telecommunication systems (UMTS) network.

A novel flexible channel allocation scheme is proposed which is applicable to medium altitude, high diversity satellite personal communication systems with an interconnected ground control segment. The scheme is built upon the establishment of several temporal master-slave network hierarchies in distinct areas of the Earth, whereby the control of radio resources in each area is granted to a single network entity, the master, located at one of the network's fixed earth station sites. The master station is entrusted with the radio resource management functionality equivalent to a base station controller in GSM, whereas the slaves, which consist of all FES sites which control satellites that have a current connectivity with the master's area, share the functionality of a GSM base transceiver station with the satellites under their control. The master maintains a table of all channel allocations within its control area in real-time, its objective is to maximise the number of channels which can be provided in its area, in response to channel requests by users, subject to known interference criteria. It can achieve this by optimising the existing and future channel allocations through the use of predictive satellite coverage, spotbeam gain models and genetic algorithms. Radio resource related signalling between master and slave stations is performed through a dedicated terrestrial fibre-optic network which interconnects the FES sites, based upon GSM interface specifications which are adapted to account for the increased propagation delays and signalling load associated with the regional network. The potential capacity gain which is available through a centralised optimisation approach over a fixed channel allocation scheme is determined through simulation. The instantaneous capacity of each scheme is highly dependent on the traffic distribution and the positions of the satellites, which causes an analytical approach to be too restrictive or simplistic. The capacity gain estimation is performed over a time period for which several samples are taken and a powerful adapted genetic algorithm is applied to the NP complete problem to determine the maximum capacity. The flexible dynamic system, entitled the hybrid-centralised DCA scheme, is shown to have a raw capacity potential in excess of the FCA scheme under the traffic distribution scenario adopted.

The complexity of today's telecommunications systems grows with each new feature introduced. As the number of services an operator provides can be used to gain advantage over competitors the number of services will continue to increase. As the complexity grows, so does the possibility for feature interactions, situations where the operation of features interfere with the operation of other features. Interactions cost more to resolve the later during the introduction of a new feature they are detected. This makes the need for analysis of feature interactions during development preeminent. There exists a multitude of frameworks and techniques for specification and analysis of models of telecommunications systems. However, we have identified that they often impose unnecessary design decisions on the models, making them untoward. In this thesis we propose a framework for specification of models of telecommunications systems. The framework is designed to describe them as general systems of communicating processes in a flexible way which allows alterations to be made late during the design. We also present definitions of interactions and how the interaction definitions are used in the framework to detect undesired interactions. A model for telephony systems is derived through observations made of common telephony concepts and constructs. Delving into concepts early in the design of the system is shown to avoid several sources of interactions. To demonstrate the potential of the framework we present a case study where the system and services described in the first interaction detection contest has been implemented and searched for interactions.

Telecommunication systems are today among the largest and most heterogeneous computer systems that exist. The functionality offered by them is rapidly increasing, by numerous features: call waiting, credit-card billing and call-forwarding to name a few. The realisation of extra services poses a challenge to implementors, in particular since different services are developed at different times and places, by different people. Not only is the number and complexity of services increasing but some vendors want to enable users to tailor their own services and ultimately design them entirely. This of course calls for rigorous control of the services so that they do not come into conflict with the interest of the vendors, other users or surprise the users with their behaviours. One way of aiding the service designers is to provide a service creation environment containing a set of well defined building blocks that would be uniform for all features, irrespective of vendor or service. Such an environment also needs tool support for writing, checking, validating and analysing for possible conflicts. We have constructed a formalism for compactly specifying the interface behaviour of the switching and service logic system underlying a service creation environment, and for specifying the behaviour of components of an environment for service creation. For this formalism we supply tool support in the form of a simulator. We have further made a formalisation, in our framework, of the ITU-T Intelligent Network model, Capability Set-1. The formalisation concerns both the underlying service architecture, in which service logic is perform by a dedicated Service Control Function, and the component language, in which Service Independent Building Blocks are composed to yield new services.

Electromagnetic wave propagation is a well-known phenomenon in the scientific world and when the first telescope was built method of sensing objects excelled afterwords. Research in optical system and infrared is growing day by day but radar system still dominates the world in object sensing. One of the benefits of using electromagnetic waves in a Radar system is that they can create images of areas which cannot be observed with optical light. Radars work on the basic phenomena of an extremely short burst of radio energy which transmit energy that reflects from the object as an echo. This principle is also known as ECHO Principal [13]. This thesis presents a Coffee Can radar system which gives detection of a stationary and moving object. Objects detection is performed on the oscilloscope using a triangular wave transmitted from an antenna, that gets reflected from an object and received on the second antenna. The prototype consists of two antennas one of which is used for transmitting signal and other is used for receiving signal. Voltage control oscillator is used to generate the RF frequency signal and power amplifiers are used before transmitting and receiving the RF signal. The signals are down-converted using a mixer the output of which is observed on an oscilloscope. Detection of the reflected signal can be performed using Doppler shift which can be determined from the velocity of electromagnetic radiation and angular displacement of the reflected waves. The wavelength of the Doppler shift is then used to indicate the detection and ranging of the object. Coffee Can radar operates at 2.4GHz with the output power of 10mW. Triangular wave signal is generated with the help of a wave generator. The radar prototype built in this thesis is used for detection and ranging of two different types of materials. First, is a metal sheet and secondly an aluminum foil.  The detection process is completed by noting the Vpp values reflected from these sheets. Vpp values are measured on the oscilloscope when the signal reflected from aluminum sheet. With the help of a commercial software, aluminum foil presence is detected under the snow. For the future work if the video amplifier is built then the aluminum foil presence can be detected on MATLAB without the help of any commercial software. In future Coffee Can Radar can also be used for surveillance purposes like smart homes, autonomous vehicles and as a jammer. This Radar system can also be used as a data logging system.

Background-Emergency 9-1-1 callers use a wide range of terms to describe abnormal breathing in persons with out-of-hospital cardiac arrest (OHCA). These breathing descriptors can obstruct the telephone cardiopulmonary resuscitation (CPR) process. Methods and Results-We conducted an observational study of emergency call audio recordings linked to confirmed OHCAs in a statewide Utstein-style database. Breathing descriptors fell into 1 of 8 groups (eg, gasping, snoring). We divided the study population into groups with and without descriptors for abnormal breathing to investigate the impact of these descriptors on patient outcomes and telephone CPR process. Callers used descriptors in 459 of 2411 cases (19.0%) between October 1, 2010, and December 31, 2014. Survival outcome was better when the caller used a breathing descriptor (19.6% versus 8.8%, P<0.0001), with an odds ratio of 1.63 (95% confidence interval, 1.17-2.25). After exclusions, 379 of 459 cases were eligible for process analysis. When callers described abnormal breathing, the rates of telecommunicator OHCA recognition, CPR instruction, and telephone CPR were lower than when callers did not use a breathing descriptor (79.7% versus 93.0%, P<0.0001; 65.4% versus 72.5%, P=0.0078; and 60.2% versus 66.9%, P=0.0123, respectively). The time interval between call receipt and OHCA recognition was longer when the caller used a breathing descriptor (118.5 versus 73.5 seconds, P<0.0001). Conclusions-Descriptors of abnormal breathing are associated with improved outcomes but also with delays in the identification of OHCA. Familiarizing telecommunicators with these descriptors may improve the telephone CPR process including OHCA recognition for patients with increased probability of survival.