Prediction of wireless communication systems performance in indoor applications

Due to a shift in the interest in wireless applications, from outdoor to indoor environments. new modelling solutions had to be designed to account for the immense complexity of the latter. Essentially, two categories of indoor propagation models prevailed until the mid-90's: the Empirical and the Physical models. They both predicted important characteristics of a given confined environment like the coverage area, transmitted power requirements. number and location of base stations or access points. The implementation of wireless communications systems onboard naval assets is expected to offer numerous advantages and enhance the existing shipboard communications systems. That, in turn, calls for a reliable and cost-effective means of estimating the expected link budget in such environments, especially when the infrastructure in question is yet to be built, as is the case in a ship class under development. This thesis treats the problem of indoor propagation modeling using the Numerical Electromagnetic Code-Basic Scattering Code (NEC-BSC) and compares the predicted results obtained by this code with actual measurements performed inside a building at the Naval Postgraduate School. A number of important conclusions regarding the validity of NEC-BSC for indoor applications are being reached and some intriguing statistical results are being presented.http://www.archive.org/details/predictionofwire00bolaLieutenant, Hellenic NavyApproved for public release; distribution is unlimited

Recolha Oportunística de Energia em Sistemas de Comunicação Sem Fios

O presente trabalho tem como objetivo apresentar um estudo comparativo entre a potência medida em três tecnologias sem fios, sendo elas o Wifi, o GSM e o DECT e identificar outros fatores que possam afetar essa potência, nomeadamente a localização tridimensional do emissor e do recetor. A medição da potência pretende identificar de uma forma prática qual a energia que poderá ser recolhida e armazenada num cenário de Energy Harvesting a partir do espectro RF. No decorrer do trabalho foram realizadas medições de potência nos canais utilizados por cada tecnologia, com a utilização de um analisador espectral sweep-tuned, para várias configurações do cenário de medição. Os resultados relativos às medições de potência são reportados na forma de várias imagens espectrais e em tabelas, onde são apresentadas as várias potências calculadas para cada cenário de medição, assim como uma análise estatística onde são calculados a variância, o desvio padrão e a incerteza recorrendo à distribuição normal t-student com um grau de incerteza de 95%. Este estudo permite concluir que em média a tecnologia onde se poderá recolher mais energia é o GSM. Tal como era esperado, é também possível concluir que a localização tridimensional do emissor e do recetor e a distância entre eles poderá influenciar significativamente a quantidade de energia que poderá ser recolhida

Improving Frequency Reuse and Cochannel Interference Coordination in 4G HetNets

This report describes my M.A.Sc. thesis research work. The emerging 4th generation (4G) mobile systems and networks (so called 4G HetNets) are designed as multilayered cellular topology with a number of asymmetrically located, asymmetrically powered, self-organizing, and user-operated indoor small cell (e.g., pico/femto cells and WLANs) with a variety of cell architectures that are overlaid by a large cell (macro cell) with some or all interfering wireless links. These designs of 4G HetNets bring new challenges such as increased dynamics of user mobility and data traffic trespassing over the multi-layered cell boundaries. Traditional approaches of radio resource allocation and inter-cell (cochannel) interference management that are mostly centralized and static in the network core and are carried out pre-hand by the operator in 3G and lower cellular technologies, are liable to increased signaling overhead, latencies, complexities, and scalability issues and, thus, are not viable in case of 4G HetNets. In this thesis a comprehensive research study is carried out on improving the radio resource sharing and inter-cell interference management in 4G HetNets. The solution strategy exploits dynamic and adaptive channel allocation approaches such as dynamic and opportunistic spectrum access (DSA, OSA) techniques, through exploiting the spatiotemporal diversities among transmissions in orthogonal frequency division multiple access (OFDMA) based medium access in 4G HetNets. In this regards, a novel framework named as Hybrid Radio Resource Sharing (HRRS) is introduced. HRRS comprises of these two functional modules: Cognitive Radio Resource Sharing (CRRS) and Proactive Link Adaptation (PLA) scheme. A dynamic switching algorithm enables CRRS and PLA modules to adaptively invoke according to whether orthogonal channelization is to be carried out exploiting the interweave channel allocation (ICA) approach or non-orthogonal channelization is to be carried out exploiting the underlay channel allocation (UCA) approach respectively when relevant conditions regarding the traffic demand and radio resource availability are met. Benefits of CRRS scheme are identified through simulative analysis in comparison to the legacy cochannel and dedicated channel deployments of femto cells respectively. The case study and numerical analysis for PLA scheme is carried out to understand the dynamics of threshold interference ranges as function of transmit powers of MBS and FBS, relative ranges of radio entities, and QoS requirement of services with the value realization of PLA scheme.1 yea

Performance of low-cost radio-over-fibre systems

The research presented in this thesis has focused on the use of radio-over-fibre (RoF) technology for improving the quality of mobile/wireless coverage within buildings. The primary aim was to minimise overall system costs by employing commercially available components. For this purpose, a distributed antenna system using low-cost vertical-cavity surface-emitting lasers (VCSELs) operating at 850 nm and multimode fibre (OM1/OM2) has been designed and implemented. A detailed link budget analysis has been performed which allows for the prediction of maximum achievable ranges for the transmission of different wireless systems over the RoF link, while taking into account practical restrictions that are important for bidirectional link operation (e.g. crosstalk and noise emissions). The analysis indicates that when optimised component parameter values are utilised, reasonable cell sizes may be achieved for systems such as GSM, UMTS and WLAN. The link budget predictions were verified for the transmission of ‘real’ WLAN signals over the designed RoF link and complete coverage of a standard office room was demonstrated. The majority of previous research into low-cost RoF links has primarily involved characterisation of the optical path. In this investigation, signal strength and throughput measurements were conducted for the combined optical and wireless paths in order to verify the operation of the complete fibre-fed WLAN system. Throughput values close to 5 Mbps for IEEE 802.11b and 20 Mbps for IEEE 802.1 lg were recorded. Additionally, the transmission of different combinations of emulated mobile/wireless systems in a dual-band configuration over another radio-over-fibre link (also employing 850 nm VCSELs and MMF) has been successfully demonstrated. Experimental investigations have been carried out for the first time to analyse the performance of WLAN-over-fibre networks using different MAC mechanisms such as fragmentation and the use of RTS/CTS in the presence of hidden nodes. Finally, scenarios involving multiple clients accessing a single remote antenna unit and multiple remote antenna units being fed by a single access point have been demonstrated

Indoor Channel Characterization at the Large and Small Scales

Náplní práce je úvod do šíření rádiových vln uvnitř budov, způsoby simulace a měření tohoto šíření. Důraz je kladen na šíření super krátkých (SKV) nebo dokonce extrémně krátkých vln (EKV) s uvážením budoucího zavádění mobilních systémů 5. generace (5G). Obsahem práce je teoretický rozbor šíření elektromagnetických vln, na jehož základě jsou implementovány simulace. Hlavní částí práce je experimentální měření úniků v rádiovém kanálu v daném frekvenčním pásmu. Měření je prováděno s dostupným vybavením a statistiky úniků jsou porovnány se známými statistickými modely úniků.The content of the work is an introduction to radio wave propagation indoors, ways of a simulation and measurement of this propagation. Emphasis is put on the propagation of the waves on super-high or even extremely high-frequency band, considering future deployment of the 5th generation of the mobile network (5G).The thesis contains the theoretical basis of the propagation of the electromagnetic waves, and on this basis, the simulations are implemented. The main part is focused on measurement of fading alongside the radio channel at given frequency band. The measurement is carried out with the available equipment, and the fading statistics is compared with well-known statistical fading models

Développement d'une méthodologie pour l'évaluation de l'exposition réelle des personnes aux champs électromagnétiques

The work presented in the thesis is directed towards addressing the requirement for determining the radio frequency (RF) exposure due to mobile phones under typical usage/ real-life scenarios and also to develop a method to predict and compare mobile phones for their real-life RF exposure. The mobile phones are characterized for their specific absorption rate (SAR) and for transmit and receive performance given by the over-the-air (OTA) characterization. Using the SAR and the total radiated power (TRP) characterization, an exposure index referred to as the SAROTA index was previously proposed to predict the real-life exposure due to mobile phones which would also serve as a metric to compare individual phones. In order to experimentally determine the real-life RF exposure, various software modified phones (SMP) are utilized for the study. These phones contain an embedded software capable of recording the network parameters. The study is undertaken in the following order: (a) Characterization of the available tools and resources for performing targeted measurements/experiments, (b) identifying the important radio resource parameters and metrics to perform the targeted measurements, (c) investigation of the actual implementation of the power control mechanism in a live network for various received signal level and received quality environments, (d) investigating the correlation of the over-the-air performance of the mobile phones and the extent of actual power control realization, (e) comparing the actual exposure and the real-life exposure as predicted by the SAROTA index. Based on the logistical and technical challenges encountered, the experiments were restricted to indoor environments to enable repeatability. During the first phase of the study, the stability of the indoor environment was evaluated. During the second phase, the influence of hand phantom on the SAR and TRP of the mobile phones and the capability of the SAROTA index to predict the exposure was investigated. Further developing on the insights from the hand phantom experiments, in the third phase, a set of identical software modified phones were externally modified to alter the TRP performance and the methodology to determine the real-life exposure and also verify the capability of the SAROTA index to predict the exposure levels was investigated. The experiments demonstrate that the SAROTA index is capable of predicting the real-life exposure and comparing the mobile phones.Le travail présenté dans cette thèse a pour objectif l’étude des conditions nécessaires pour évaluer l'exposition radio fréquence (RF) due aux téléphones mobiles dans un scenario d’utilisation réelle et le développement d’une méthodologie permettant de prédire et de comparer les téléphones mobiles en fonction de leurs expositions RF réelles. Les téléphones mobiles sont caractérisés par leur débit d'absorption spécifique (DAS) et leur performance en émission et en réception (over-the-air, OTA). En utilisant le DAS et la puissance totale rayonnée (PTR), un indice d'exposition appelée l'indice SAROTA a été proposé précédemment afin de prévoir l'exposition réelle des téléphones mobiles. L’indice SAROTA sert ainsi de métrique permettant de comparer les téléphones mobiles. Afin de déterminer expérimentalement l’exposition réelle aux RF, plusieurs téléphones avec des modifications logicielles permettant d’enregistrer les paramètres du réseau, sont utilisés pour l’étude qui est menée comme suit : (a) caractérisation des outils et des ressources disponibles pour effectuer des mesures ciblées, (b) identification des ressources radio et des paramètres importants pour effectuer ces mesures, (c) étude de la mise en œuvre effective du mécanisme de contrôle de puissance observé dans un réseau mobile réel pour différents niveaux et de qualités du signal reçus, (d) étude de la corrélation entre la performance OTA des téléphones mobiles et l’étendue effective du contrôle de puissance appliquée par le réseau, (e) comparaison entre la valeur réelle de l’exposition et la valeur prédite en utilisant l’indice SAROTA. Comme les défis logistiques et techniques sont plus difficiles à surmonter pour les mesures dans un environnement multi-trajets extérieur, les expériences ont été limitées à des environnements intérieurs pour assurer une meilleure répétabilité des mesures. Lors d’une première phase de l’étude, la stabilité de l’environnement intérieur a été évaluée. Lors d’une deuxième phase, l’influence de la main sur le DAS et la PTR des téléphones mobiles ainsi que sur l’évaluation de l’exposition réelle prédite par l’indice SAROTA a été étudiée. Lors d’une troisième phase, un ensemble de téléphones mobiles identiques ont été modifiés et des mesures effectuées pour vérifier que l’indice SAROTA permet bien de prédire l’exposition réelle des personnes