This thesis investigates optimization of advanced telecommunication algorithms from power and performance perspectives. The algorithms chosen are MIMO and LDPC. MIMO is implemented in custom ASIC for power optimization and LDPC is implemented on dynamically reconfigurable fabric for both power and performance optimization. Both MIMO and LDPC are considered computational bottlenecks of current and future wireless standards such as IEEE 802.11n for Wi-Fi and IEEE 802.16 for WiMax applications. Optimization of these algorithms is carried out separately. The thesis is organized implicitly in two parts. The first part presents selection and analysis of the VBLAST receiver used in MIMO wireless system from custom ASIC perspective and identifies those processing elements that consume larger area as well as power due to complex signal processing. The thesis models a scalable VBLAST architecture based on MMSE nulling criteria assuming block rayleigh flat fading channel. After identifying the major area and power consuming blocks, it proposes low power and area efficient VLSI architectures for the three building blocks of VBLAST namely Pseudo Inverse, Sorting and NULLing & Cancellation modules assuming a 4x4 MIMO system. The thesis applies dynamic power management, algebraic transformation (strength reduction), resource sharing, clock gating, algorithmic modification, operation substitution, redundant arithmetic and bus encoding as the low power techniques applied at different levels of design abstraction ranging from system to architecture, to reduce power consumption. It also presents novel architectures not only for the constituent blocks but also for the whole receiver. It builds the low power VBLAST receiver for single carrier and provides its area, power and performance figures. It then investigates into the practicality and feasibility of VBLAST into an OFDM environment. It provides estimated data with respect to silicon real estate and throughput from which conclusion can easily be drawn about the feasibility of VBLAST in a multi carrier environment. The second part of the thesis presents novel architectures for the real time adaptive LDPC encoder and decoder as specified in IEEE 802.16E standard for WiMax application. It also presents optimizations of encoder as well as decoder on RICA (Reconfigurable Instruction Cell Architecture). It has searched an optimized way of storing the H matrices that reduces the memory by 20 times. It uses Loop unrolling to distribute the instructions spatially depending upon the available resources to execute them concurrently to as much as possible. The parallel memory banks and distributed registers inside RICA allow good reduction in memory access time. This together with hardware pipelining provides substantial potential for optimizing algorithms from power and performance perspectives. The thesis also suggests ways of improvements inside RICA architecture.

Modern day technology aspires to always progress. This progression leads to a lot of research in any significant area of improvement. There is a growing amount of end-users in the wireless spectrum which has led to a need for improved bandwidth usage and BER values. In other words, new technologies which would increase the capacity of wireless systems are proving to be a crucial point of research in these modern times. Different combinations of multiuser receivers are evaluated to determine performance under normal working conditions by comparing their BER performance charts. Multiple input, multiple output (MIMO) systems are incorporated into the system to utilise the increased capacity rates achievable using the MIMO configuration. The effect of MIMO on the technologies associated with modern day technological standards such as CDMA and OFDM have been investigated due to the significant capacity potentials these technologies normally exhibit in a single antenna scenario. An in-depth comparison is established before comparison is made with a conventional maximum likelihood (ML) detector. The complexity of the ML detector makes its realization evaluated in such a manner to achieve the same or near ML solution but with lower computational complexity. This was achieved using a proposed modification of the Schnorr-Euchner Sphere decoding algorithm (SE-SDA). The proposed sphere decoder (P-SD) adopts a modification of the radius utilised in the SE-SDA to obtain a near ML solution at a much lower complexity compared to the conventional ML decoder. The P-SD was configured to work in different MIMO antenna configurations. The need for the highest possible data rates from the available limited spectrum led to my research into the multi-user detection scenario and MIMO.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Neste trabalho, avaliou-se o desempenho de transceptores MIMO (do inglÃs, Multiple-Input-Multiple-Output) em uma nova arquitetura proposta para os sistemas de comunicaÃÃes mÃveis sem fio de prÃxima geraÃÃo XG (do inglÃs, Next Generation) denotada como CoMP (do inglÃs, Coordinated Multi-Point), em comparaÃÃo com uma arquitetura co-localizada, em que, os equipamentos de usuÃrios utilizam os recursos unicamente da estaÃÃo rÃdio base a qual està localizado. Com o objetivo de se obter ganhos de multiplexaÃÃo espacial, diversidade e ganhos intermediÃrios (entre os dois possÃveis ganhos), adota-se transceptores MIMO, os quais sÃo submetidos a dois cenÃrios distintos: CenÃrio 1, composto por uma cÃlula co-localizada que tem uma cobertura equivalente a das trÃs cÃlulas cooperativas e um cenÃrio 2, em que a cÃlula co-localizada tem o mesmo tamanho das cÃlulas cooperativas. Em ambos os casos, as arquiteturas CoMP e co-localizada sÃo abordadas e avalia-se o desempenho comparativo entre os cenÃrios relacionado com as duas arquiteturas. A anÃlise realizada neste trabalho à dividida em duas partes, sendo uma de carÃter sistÃmico, em que se observa o comportamento da SINR (do inglÃs, Signal to Interference plus Noise Ratio) utilizando os transceptores VBLAST (do inglÃs, Vertical Bell-Labs Space-Time) e STBC (do inglÃs, Space-Time Block Codes), e a outra de carÃter de enlace, na qual se utiliza um transceptor MIMO hÃbrido, de modo a fornecer uma anÃlise da taxa de erro de bit. Os resultados mostram que por meio da cooperaÃÃo, um desempenho semelhante ao cenÃrio Co-localizado pode ser obtido com um menor nÃmero de antenas nas estaÃÃes rÃdio base, representando uma economia do ponto de vista de dispÃndio de capital CAPEX (do inglÃs, Capital Expenditure) e operacional OPEX (do inglÃs, Operational Expenditure) da rede, bem como reduÃÃo na taxa de erro. / In this work, we evaluated the performance of MIMO (Multiple-Input-Multiple-Output) transceivers on a new architecture proposed to mobile wireless communications systems of next generation XG (Next Generation), denoted by CoMP (Coordinate Mult-Point), which is compared with a co-located architecture, whose user equipments utilize the resources uniquely of the radio base station, which is located. In order to obtain spatial multiplexing gains, diversity and intermediate gains (between the two possible gains), adopts MIMO transceivers, which are submitted to different scenarios: Scenario 1, is composed of a co-located cell, whose coverage area is equivalent to three cooperative cells and Scenario 2, where the co-located cell has the same cooperative cell sizes. In both cases, CoMP architectures and co-located are addressed and evaluates the comparative performance between these scenarios, related to the two architecture. The current analysis is divided into two parts: a systemic character, where observes the SINR (Signal to Interference plus Noise Ratio) behavior with the use of VBLAST (Vertical-Bell Labs Space-Time) and STBC (Space-Time Block Codes) transceivers, the another one, of link character, which uses a hybridMIMO transceiver G2+1, in oder to provide an analysis of the bit error rate. The results show that by means of cooperation, a performance similar to the scenario co-located can be obtained with a smaller number of antennas at base stations, representing a saving in terms of capital expenditure CAPEX (Capital Expenditure) and operational OPEX (Operational Expenditure) network, as well as, a reduction in the error rate.