Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Cloud RAN for Mobile Networks - a Technology Overview

Cloud Radio Access Network (C-RAN) is a novel mobile network architecture which can address a number of challenges the operators face while trying to support growing end-user’s needs. The main idea behind C-RAN is to pool the Baseband Units (BBUs) from multiple base stations into centralized BBU Pool for statistical multiplexing gain, while shifting the burden to the high-speed wireline transmission of In-phase and Quadrature (IQ) data. C-RAN enables energy efficient network operation and possible cost savings on base- band resources. Furthermore, it improves network capacity by performing load balancing and cooperative processing of signals originating from several base stations. This article surveys the state-of-the-art literature on C-RAN. It can serve as a starting point for anyone willing to understand C-RAN architecture and advance the research on C-RA

Spectrum Optimisation in Wireless Communication Systems: Technology Evaluation, System Design and Practical Implementation

Two key technology enablers for next generation networks are examined in this thesis, namely Cognitive Radio (CR) and Spectrally Efficient Frequency Division Multiplexing (SEFDM). The first part proposes the use of traffic prediction in CR systems to improve the Quality of Service (QoS) for CR users. A framework is presented which allows CR users to capture a frequency slot in an idle licensed channel occupied by primary users. This is achieved by using CR to sense and select target spectrum bands combined with traffic prediction to determine the optimum channel-sensing order. The latter part of this thesis considers the design, practical implementation and performance evaluation of SEFDM. The key challenge that arises in SEFDM is the self-created interference which complicates the design of receiver architectures. Previous work has focused on the development of sophisticated detection algorithms, however, these suffer from an impractical computational complexity. Consequently, the aim of this work is two-fold; first, to reduce the complexity of existing algorithms to make them better-suited for application in the real world; second, to develop hardware prototypes to assess the feasibility of employing SEFDM in practical systems. The impact of oversampling and fixed-point effects on the performance of SEFDM is initially determined, followed by the design and implementation of linear detection techniques using Field Programmable Gate Arrays (FPGAs). The performance of these FPGA based linear receivers is evaluated in terms of throughput, resource utilisation and Bit Error Rate (BER). Finally, variants of the Sphere Decoding (SD) algorithm are investigated to ameliorate the error performance of SEFDM systems with targeted reduction in complexity. The Fixed SD (FSD) algorithm is implemented on a Digital Signal Processor (DSP) to measure its computational complexity. Modified sorting and decomposition strategies are then applied to this FSD algorithm offering trade-offs between execution speed and BER

OBSAI interoperability in multi-vendor WiMAX base station architecture

Wireless networks have become a necessity with the increased mobility in human life. From cellular telephony to the Internet, all types of communication are now provided over wireless networks. However, to offer wireless network coverage over an area requires a potentially expensive infrastructure deployment. Such deployment requires base stations which until now have been completely proprietary to the equipment vendors. Moreover, proprietary equipment is almost always costly and offer less flexibility than standardized modular solutions. This situation results in a high cost for network upgradation and hinders network development. A remedy is available via modularization, hence the Open Base Station Architecture Initiative (OBSAI) is trying to modularize and standardize one of the most expensive elements of the wireless infrastructure, the base station. OBSAI standards aim to modularize the base station architecture and enable true interoperability among the various modules. However, the goal has not yet been achieved due to some features of the standard. This thesis project has studied the standards and pointed out some areas that must be concentrated upon when performing interoperability tests. It also proposes several standards amendments to foster greater interoperability among the modules of a base station. This study focuses on the RP3 interface of the OBSAI specification with the goal of making truly inter-operable baseband and RF modules, thus commoditizing the modules. The result is expected to be lower cost, greater interoperability, faster time-to-market, and more cooperative research

Evaluating WIMAX for real-time vehicular communications

Mestrado em Engenharia Electrónica e TelecomunicaçõesOs acidentes rodoviários têm um impacto elevado na sociedade, quer devido às perdas humanas daí resultantes quer devido aos custos económicos associados. Este facto tem causado por todo o mundo o estudo de mecanismos que permitam aumentar a segurança rodoviária. Um exemplo disto é o investimento da Europa em vários projectos com vista a desenvolver estes mecanismos, onde a maior parte destas iniciativas consideram a possibilidade dos veículos comunicarem entre si e/ou com estações fixas, situadas junto da rodovia. A mobilidade dos veículos apresenta requisitos especiais, onde as comunicações sem-fios têm um papel crucial nestas aplicações. Contudo, os serviços de segurança rodoviária requerem alguns requisitos específicos, como largura de banda ou em termos de timeliness, que têm de ser cumpridos independentemente da tecnologia sem-fios usada. Neste trabalho é pretendido avaliar WiMAX para comunicações relacionadas com a segurança rodoviária, em que a coexistência de diferentes tipos de serviços é uma realidade, onde o uso dos mecanismos de qualidade de serviço fornecidos pelo WiMAX podem ser uma vantagem. ABSTRACT: Road accidents have a huge impact on the society, both because of the resulting human life losses and injuries as well as because of the associ- ated economic costs. This situation fostered the study of mechanisms for increasing road safety all over the world. In Europe, several projects are being funded to develop such mechanisms. Many of the approaches that are being pursued require the ability of the vehicles to communicate with each other and/or with fixed roadside equipments. Due to the mobility con- straints, wireless technologies have a crucial role in this kind of applications. However, road safety services have also specific demands, in terms of band- width and timeliness, that have to be met, independently of the wireless technology used. In this work, it is performed an evaluation of WiMAX for road safety communications, taking into consideration the coexistence of different types of service and that the use of quality of service mechanisms in this wireless technology could be an advantage