Nowadays, with a worldwide market penetration of over 50% in the mobile telecommunications sector, there is also an unrelenting demand from the subscribers for ever increasing transmission rates and availability of broadband-like experience on the handset. Due to this, research in next-generation networks is rife. Such systems are expected to achieve peak data rates of up to 1 Gbps through the use of innovative technologies such as multiple-input and multipleoutput (MIMO) and orthogonal frequency division multiple access (OFDMA). Two more ways of boosting capacity have also been identified: shrinking cell sizes and greater reuse of resources in the same area. This forms the foundation of the research presented in this thesis. For operators, the costs involved with planning and deploying additional network infrastructure to provide a dense coverage of small, high capacity cells cannot be justified. Femto-cells, however, promise to fulfil this function. These are user-deployed mini base stations (BSs), known as home evolved NodeBs (HeNBs), which are envisaged to be commonplace in homes and offices in the coming years. Since they drastically reduce communication distances to user equipments (UEs) and reuse the resources already utilised in the macro-cell, they help boost the system capacity significantly. However, there are issues to be addressed with the deployment of femto-cells, such as increased interference to the system and methods of access. These and other problems are discussed and analysed in this thesis. One of the first steps towards femtocell research has been the study of the time division duplex (TDD) underlay concept, whereby an indoor UE acts as a relay between the evolved NodeB (eNB) and other indoor UEs. In order to gain a deeper understanding of how and under what conditions such a self-organising network can be deployed, a mathematical analysis of the distribution of path losses in a network of uniformly distributed nodes has been performed. In connection with this, research has also been done in the identification of well connected nodes in such networks. Next, extensive simulations on traditional cellular networks with embedded femto-cells have been carried out in order to demonstrate the benefits of femto-cell deployment. This research has shown that femto-cells can cause severe downlink (DL) interference to badly placed macro UEs. Finally, a novel interference avoiding technique that addresses this problem is investigated.

Long Term Evolution (LTE) is the latest mobile network technology published by the Third Generation Partnership Project (3GPP). It might become a dominant technology for the next generation and it is attract-ing a great deal of attention from the top global corporations. IxLoad is a real-world traffic emulator, designed by the test solution provider Ixia. Mobile Packet Gateway (MPG) has been developed by Ericsson and is a commercial network equipment to provide a smart interface between mobile network (Global System for Mobile Communi-cation (GSM), Wideband Code Division Multiple Access (WCDMA), LTE) and internet for operators’ network. In this thesis, MPG is utilized to assess the capacity and LTE functionality of IxLoad. Capacity estima-tion will verify the maximum simulated users that can be supported by IxLoad and will test the maximum throughput IxLoad can achieve with a particular number of simulated users, under conditions involving a particular application scenario such as browsing HTTP. In addition to Session Management some other features such as Track Area Update and Handover, Busy Hour Functionality, Deep Packet Inspection, Mul-tiple Access Point Names (APNs) and Dynamic Quality of Service Enforcement are also covered in the functionality assessment. Moreover, this thesis gives a brief introduction to Evolved Packet Sys-tem (EPS), Evolved Packet Core (EPC), and to the functionality of MPG in addition to the role of MPG in EPS. Meanwhile the newest features of IxLoad are also presented in this document. Finally, as the outcome of this thesis, several suggestions are proposed in relation to improve-ments for IxLoad and MPG.

Made available in DSpace on 2016-03-15T19:37:56Z (GMT). No. of bitstreams: 1 BRUNO FERRAZ IZARIO.pdf: 4620887 bytes, checksum: bd842cabfdadb0bcb55e0ea548c9fba5 (MD5) Previous issue date: 2015-08-28 / The Long Term Evolution (LTE) system belongs to the 4th generation phone system. It is standardized by 3GPP and utilizes several technologies to improve the performance of data transmission. This permits flexibility for mobile devices, which enables a high data rate in the range of 50 Mbps to 100 Mbps, and admit access to various multimedia services. The study presents the results of deploying an LTE network in the city of Campinas, São Paulo, Brazil, using the 700 MHz band by comparing it to the 2.5 GHz band. By calculating the budget for the LTE system link is information as possible to highlight throughput and cell coverage radius, and other information. The Radio Mobile software was used for verification of results. / O sistema Long Term Evolution (LTE) pertence ao sistema da 4ª geração de telefonia (4G). Ele é padronizado pelo 3GPP e utiliza diversas tecnologias para melhorar o desempenho de transmissão de dados. O mesmo permite uma flexibilidade para dispositivos móveis, possibilitando uma alta taxa de dados na faixa de 50 Mbps a 100 Mbps, além de admitir acesso a diversos serviços multimídias. O estudo apresenta resultados de implantação de uma rede LTE na cidade de Campinas, São Paulo, Brasil, utilizando a faixa de 700 MHz comparando-a com a faixa de 2,5 GHz. Através do cálculo de link budget para o sistema LTE, é possível destacar informações como throughput e raio da célula de cobertura, além de outras informações. O software radio mobile foi utilizado para fins de comprovação de resultados.

A tablet computer antenna array for WWAN/LTE and LTE MIMO operations is proposed. The antenna array comprises a main antenna and an auxiliary antenna. The main antenna is an eight-band coupled-fed antenna, which can cover the GSM850/900/1800/1900/UMTS and LTE700/2300/2700 operations. The auxiliary antenna is a three-band antenna, which can cover the LTE700/2300/2500 operation and occupies a small size. Acceptable isolation between the main and auxiliary antennas has also been obtained, which makes it promising for the main and auxiliary antennas to perform LTE MIMO operation in the LTE700/2300/2500 bands. Effects of the internal tablet computer antenna on the user¡¦s body are also studied. The obtained results show that the antenna can meet the 1-g body SAR specification of less than 1.6 W/kg by selecting a proper distance between the antenna and the flat phantom. Also, since the user¡¦s body is a lossy material, a decrease in the antenna¡¦s radiation efficiency is observed when the user¡¦s body is in the vicinity of the internal antenna.

In this thesis, WWAN/LTE and LTE MIMO antennas for ultrabook computers are presented. The MIMO antenna system comprises an eight-band LTE/WWAN antenna and a three-band LTE antenna. The bandwidth of the eight-band LTE/WWAN antenna is enhanced by using an embedded parallel resonant circuit, which can result in dual-resonance excitation of the lowest resonant mode of the antenna. The bandwidth of the antenna¡¦s lower band can hence cover the LTE700/GSM850/900 operation. A design technique of improving the isolation of the MIMO antenna system is also presented. The isolation enhancement is obtained by embedding a 0.5-wavelength slot in the conductive supporting plate of the upper cover of the ultrabook computer. The embedded slot can attract the excited surface currents in the conductive supporting plate and decrease the coupling between the MIMO antennas through the coupling of the surface currents. The isolation between the MIMO antennas can hence be enhanced. Moreover, this technique will not lead to decreased radiation efficiency and impedance matching of the MIMO antennas, which is attractive for practical applications.