The recent increase of mobile data usage and emergence of new applications such as Online Gaming, mobile TV, Web 2.0, Streaming Contents have greatly motivated the 3rd Generation Partnership Project (3GPP) to work on the Long Term Evolution (LTE). The LTE is the latest standard in the mobile network technology tree. It inherits and develops the GSM/EDGE and UMTS/HSPA network technologies and is a step toward the 4th generation (4G) of radio technologies designed to optimize the capacity and speed of 3G mobile communication networks. In this thesis, the LTE system capacity and coverage are investigated and a model is proposed on the base of the Release 8 of 3GPP LTE standards. After that, the frequency planning of LTE is also studied. The results cover the interference limited coverage calculation, the traffic capacity calculation and radio frequency assignment. The implementation is achieved on the WRAP software platform for the LTE Radio Planning.

<p>The demand for wireless communications is increasing every year, but the available resources are not increasing at the same rate. It is very important that the radio resources are used in an efficient way allowing the networks to support as many users as possible. The three types of networks studied in this thesis are frequency hopping GSM networks, ad hoc multi-hop networks and WCDMA networks.</p><p>One type of network with a promising future is ad hoc multi-hop networks. The users in this kind of networks communicate with each other without base stations. Instead the signal can be sent directly between two users, or relayed over one or several other users before the final destination is reached. Resources are shared by letting the users transmit in time slots. The problem studied is to minimize the number of time slots used, when the users broadcast. Two different optimization models are developed for assigning time slots to the users. A reduction of the number of time slots means a shorter delay for a user to transmit next time.</p><p>The rapid growth of the number of subscribers in cellular networks requires efficient cell planning methods. The trend of smaller cell sizes in urban areas for higher capacity raise the need for more efficient spectrum usage. Since the infrastructure of a second generation cellular system, such as GSM, already exists, and the available bandwidth of an operator is limited, frequency planning methods are of utmost importance. Because of the limited bandwidth in a GSM network, the frequencies must be reused. When planning a GSM network the frequencies can not be reused too tightly due to interference. The frequency planning problem in a GSM network is a very complex task. In this thesis an optimization model for frequency assignment in a frequency hopping GSM network is developed. The problem is to assign frequencies to the cells in the network, while keeping the interference to a minimum. Different meta heuristic methods such as tabu search and simulated annealing are used to solve the problem. The results show that the interference levels can be reduced to allow a capacity increase.</p><p>The demand for sending more information over the wireless communication systems requires more bandwidth. Voice communication was handled well by the second generation cellular systems. The third generation of mobile telecommunication systems will handle data transmissions in a greater extent. The last type of network considered in the thesis is a WCDMA cellular network. The aim is to schedule the transmission of packet data from the base station to the users. Scheduling models that maximize the utility are developed for both the downlink shared channel and the high speed downlink shared channel.</p>

The demand for wireless communications is increasing every year, but the available resources are not increasing at the same rate. It is very important that the radio resources are used in an efficient way allowing the networks to support as many users as possible. The three types of networks studied in this thesis are frequency hopping GSM networks, ad hoc multi-hop networks and WCDMA networks. One type of network with a promising future is ad hoc multi-hop networks. The users in this kind of networks communicate with each other without base stations. Instead the signal can be sent directly between two users, or relayed over one or several other users before the final destination is reached. Resources are shared by letting the users transmit in time slots. The problem studied is to minimize the number of time slots used, when the users broadcast. Two different optimization models are developed for assigning time slots to the users. A reduction of the number of time slots means a shorter delay for a user to transmit next time. The rapid growth of the number of subscribers in cellular networks requires efficient cell planning methods. The trend of smaller cell sizes in urban areas for higher capacity raise the need for more efficient spectrum usage. Since the infrastructure of a second generation cellular system, such as GSM, already exists, and the available bandwidth of an operator is limited, frequency planning methods are of utmost importance. Because of the limited bandwidth in a GSM network, the frequencies must be reused. When planning a GSM network the frequencies can not be reused too tightly due to interference. The frequency planning problem in a GSM network is a very complex task. In this thesis an optimization model for frequency assignment in a frequency hopping GSM network is developed. The problem is to assign frequencies to the cells in the network, while keeping the interference to a minimum. Different meta heuristic methods such as tabu search and simulated annealing are used to solve the problem. The results show that the interference levels can be reduced to allow a capacity increase. The demand for sending more information over the wireless communication systems requires more bandwidth. Voice communication was handled well by the second generation cellular systems. The third generation of mobile telecommunication systems will handle data transmissions in a greater extent. The last type of network considered in the thesis is a WCDMA cellular network. The aim is to schedule the transmission of packet data from the base station to the users. Scheduling models that maximize the utility are developed for both the downlink shared channel and the high speed downlink shared channel.

The allocation of frequency spectrum by the FCC for Ultra Wideband (UWB) communications in the 3.1-10.6 GHz has paved the path for very high data rate Gb/s wireless communications. Frequency synthesis in these communication systems involves great challenges such as high frequency and wideband operation in addition to stringent requirements on frequency hopping time and coexistence with other wireless standards. This research proposes frequency generation schemes for such radio systems and their integrated implementations in silicon based technologies. Special emphasis is placed on efficient frequency planning and other system level considerations for building compact and practical systems for carrier frequency generation in an integrated UWB radio. This work proposes a frequency band plan for multiband OFDM based UWB radios in the 3.1-10.6 GHz range. Based on this frequency plan, two 11-band frequency synthesizers are designed, implemented and tested making them one of the first frequency synthesizers for UWB covering 78% of the licensed spectrum. The circuits are implemented in 0.25µm SiGe BiCMOS and the architectures are based on a single VCO at a fixed frequency followed by an array of dividers, multiplexers and single sideband (SSB) mixers to generate the 11 required bands in quadrature with fast hopping in much less than 9.5 ns. One of the synthesizers is integrated and tested as part of a 3-10 GHz packaged receiver. It draws 80 mA current from a 2.5 V supply and occupies an area of 2.25 mm2. Finally, an architecture for a UWB synthesizer is proposed that is based on a single multiband quadrature VCO, a programmable integer divider with 50% duty cycle and a single sideband mixer. A frequency band plan is proposed that greatly relaxes the tuning range requirement of the multiband VCO and leads to a very digitally intensive architecture for wideband frequency synthesis suitable for implementation in deep submicron CMOS processes. A design in 130nm CMOS occupies less than 1 mm2 while consuming 90 mW. This architecture provides an efficient solution in terms of area and power consumption with very low complexity.

One of the main challenges posed by 4G wireless communication systems is achieving flexible, programmable multi-standard radio transceivers with maximum hardware share amongst different standards at a minimum power consumption. Evaluating the feasibility and performance of different multi-standard/multi-band radio solutions at an early stage, i.e. system level, is key for succeeding in surmounting this challenge. This entails for- mulation of the transceiver budget for several RF architectures and frequency plans with different degrees of hardware sharing. This task is complicated by the fact that transceiver blocks can have different implementations that lead to different performances. The tools that are available for use at present have only analysis capabilities or address only one standard and/or receiver architecture at a time.In the belief that a new approach to this problem is necessary, the work that has led to this thesis proposes a novel methodology that automates the design-space explo- ration of integrated multi-standard wireless radio receivers. This methodology has been implemented in a multi-standard RF Transceiver Architecture Comparison Tool, TACT. TACT helps surmounting many of the challenges faced by RF system designers targeting multi-standard/multi-band radio receivers.The goal of the algorithms TACT is built upon is to find a multi-standard receiver frequency plan and budget that meets or exceeds the specifications of the addressed wire- less standards while keeping the requirements of each of the receiver blocks as relaxed as possible. TACT offers RF engineers a deep insight into the receiver behavior at a very early stage of the design flow. It models the impact of critical circuit non-idealities using a high level of abstraction. This reduces the number of design iterations and, thus, the time-to-market of the solution. The reuse of already available intellectual property (IP) blocks is also considered in TACT, what can result in a significant cost reduction of the receiver implementation. A combination of a behavioural-based cooperative multi-agent optimization and deterministic techniques is proposed.The capabilities of the proposed techniques and developed tool are illustrated through case studies addressing different design challenges the design of multi-standard receivers present.The last part of this thesis is devoted to one of the key blocks of any communica- tions receiver: the analog-to-digital converter. This work focuses on modeling and design methodologies for continuous-time ΔΣ modulators. A method to evaluate the stability margin of continuous-time ΔΣ modulators as a function of the timing uncertainty effects is proposed. / QC 20100907 / RaMSiS

[pt] Um algoritmo de alocação de freqüência eficiente deve considerar aspectos de propagação e detalhes de equipamento de modo a minimizar a relação a sinal interferência, e conseqüentemente, aumentar a eficiência do espectro. Essa dissertação tem o objetivo de propor uma melhor solução para alocação de freqüência nas rede TDMA e GSM, levando em consideração os aspectos citados. A abordagem utilizada é diferente das técnicas de alocação de freqüências usuais, que são baseadas na distância de reuso. O algoritmo proposto utiliza uma matriz que representa os aspectos de propagação (matriz de isolação) e uma matriz que representa os detalhes do equipamento (matriz de compatibilidade). A matriz de isolação mostra a relação sinal interferência que cada célula tem com as outras. Um estudo de como coletar os dados (seleção da rota no interior do setor) e de como trabalhar com os dados coletados foram realizados, objetivando-se ter matriz que melhor caracterizasse a rede utilizada. A matriz de compatibilidade mostra a distância em freqüência no qual se devem alocar os canais em uma mesma célula, células adjacentes e células co-sites. Os valores de espaçamento entre freqüências, sugeridos nesta dissertação, são valores práticos e dependem das técnicas utilizadas no planejamento e do equipamento utilizado em questão. O problema de alocação foi modelado com um problema inteiro. Uma heurística (divide and conquer) foi utilizada para particionar a rede em menores partes, em que o algoritmo branch and bound foi implementado. O algoritmo foi testado em duas redes com sessenta e trezentos e quarenta e oito setores respectivamente. As redes foram construída levando em consideração os dados topográficos e morfológicos da cidade de Brasília. / [en] An efficient frequency assignment algorithm should consider both propagation conditions and equipment details, in order to minimize the carrier-to-interference ratio (C/I) and, as a result, to increase spectrum efficiency. This dissertation proposes a way to obtain a better solution for frequency assignment in TDMA and GSM networks, taking into account propagation conditions and equipment details. The proposed approach is different from usual frequency assignment techniques based on reuse distance. A frequency assignment algorithm proposed uses one matrix that represents the propagation features (isolation matrix) and another which represents the equipment details (compatibility matrix). The isolation matrix shows the signal to interference ratio between any two sectors in the whole network. A survey to define how to collect the data ( selection of the route inside the sector) and how to work with data collected was developed, aiming to obtain the best matrix representation of the network. The compatibility matrix shows the frequency distance between channels in the same sector, adjacent sector and co-site sectors. The frequency space values used in this matrix are practical values, which depend upon the technique used on the planning and on the utilized hardware. The frequency assignment was formulated as an integer problem. An heuristic (divide and conquer) was used to split the network into smaller parts where an exact algorithm branch and bound was implemented. The algorithm was tested on two networks with 60 and 348 sectors respectively. The networks were built having the topographical and morphological data from Brasilia city. / [es] Un algoritmo eficiente de asignación de frecuencia debe considerar aspectos de propagación y detalles del equipo de modo tal que se minimize la relación señal-interferencia, y onsecuentemente, aumente la eficiencia del espectro. Esta disertación tiene como objetivo proponer una solución para la asignación de frecuencia en las redes TDMA y GSM, considerando los aspectos anteriormente citados. El enfoque utilizado difiere de las técnicas de asignación de frecuencias usuales, baseadas en la distancia de reuso. EL algoritmo propuesto utiliza una matriz que representa los aspectos de propagación (matriz de aislamiento) y una matriz que representa los detalles del equipo (matriz de compatibilidade). La matriz de aislamiento muestra la relación señal-interferencia que cada célula tiene con las otras. Se realiza un estudio de como recolectar los datos (selección de la ruta en el interior del sector) y de como trabajar con los datos recolectados, con el objetivo de obtener la matriz que mejor caracteriza la red utilizada. La matriz de compatibilidad muestra la distancia en frecuencia en la cual se deben alocar los canales en una misma célula, células adyacentes y células co-sites. Los valores de espacio entre frecuencias, sugeridos en esta disertación, son valores prácticos y dependen de las técnicas utilizadas en el planificación y del equipo utilizado. El problema de asignación fue modelado como un problema entero. Fue utilizada una heurística (divide and conquer) para particionar la red en menores partes, donde se implementó el algoritmo branch and bound. EL algoritmo fue probado en dos redes con sesenta y trezentos y quarenta y oito sectores respectivamente. Las redes fueron construidas considerando los datos topográficos y morfológicos de la ciudad de Brasilia.

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