Test and evaluation (TandE) is a critically important step before in-the-field deployment of radio-frequency (RF) hardware in order to assure that the hardware meets its design requirements and specifications. Typically, TandE is performed either in a lab setting utilizing a software simulation environment or through real-world field testing. While the former approach is typically limited by the accuracy of the simulation models (particularly of the anticipated hardware effects) and by non-real-time data rates, the latter can be extremely costly in terms of time, money, and manpower. To build upon the strengths of these approaches and to mitigate their weaknesses, this work presents the development of an FPGA-based TandE tool that allows for real-time pseudo-random aggregate signal generation for testing RF receiver hardware (such as communication receivers, spectrum sensors, etc.). In particular, a framework is developed for an FPGA-based implementation of a test signal emulator that generates randomized aggregate spectral environments containing signals with random parameters such as center frequencies, bandwidths, start times, and durations, as well as receiver and channel effects such as additive white Gaussian noise (AWGN). To test the accuracy of the developed spectrum generation framework, the randomization properties of the framework are analyzed to assure correct probability distributions and independence. Additionally, FPGA implementation decisions, such as bit precision versus accuracy of the generated signal and the impact on the FPGA's hardware footprint, are analyzed.This analysis allows the test signal engineer to make informed decisions while designing a hardware-based RF test system. This framework is easily extensible to other signal types and channel models, and can be used to test a variety of signal-based applications. / Master of Science / Test and evaluation (TandE) is a critically important step before in-the-field deployment of radio-frequency signal hardware in order to assure that the hardware meets its design requirements and specifications. Typically, TandE is performed either in a lab setting utilizing a software simulation or through real-world field testing. While the former approach is typically limited by the accuracy of the simulation models and by slower data rates, the latter can be extremely costly in terms of time, money, and manpower. To address these issues, a hardware-based signal generation approach that takes the best of both methods mentioned above is developed in this thesis. This approach allows the user to accurately model a radio-frequency system without requiring expensive equipment. This work presents the development of a hardware-based TandE tool that allows for real-time random signal generation for testing radio-frequency receiver hardware (such as communication receivers). In particular, a framework is developed for an implementation of a test signal emulator that allows for user-defined randomization of test signal parameters such as frequencies, signal bandwidths, start times, and durations, as well as communications receiver effects. To test the accuracy of the developed emulation framework, the randomization properties of the framework are analyzed to assure correct probability distributions and independence. Additionally, hardware implementation decisions such as bit precision versus quality of the generated signal and the impact on the hardware footprint are analyzed. Ultimately, it is shown that this framework is easily extensible to other signal types and communication channel models.

In recent years there is growing research in optical wireless communication. This growing popularity isdue to several characteristics like such as large bandwidth that is also not having spectrum regulationsimposed, low cost and license-free operation. Since visible light communications (VLC) is a branch ofoptical wave communications (OWC), it is used for replacing RF communications. The other primaryreason for the use of visible light communications [1], because it uses 400 THz of unlicensed secure andradio free media for wireless communications which are 1000 times more than that of radiocommunications. For transmission of VLC, we use LED as light sources.Due to the high efficiency and less power consumption LED have replaced the oldfluorescence lamps, LED provide the dual functionality they can provide lighting and can providecommunications (transfer of data) just like Wi-Fi. In LED the on and off state is so fast that the humaneye can’t even perceive it. The on and off state can be taken as 1 and 0’s and through this we can transferthe data, this type of modulation is called OOK keying modulation it is used for single carrier modulationscheme. We can interpret the data that is received from the transceiver side with the help of thephotodiode at the receiver’s side. This communication technique can provide better security as there is nointerference, as light can't penetrate through walls leaving the data transfer to the room itself. ThroughVLC we can offer better security to data over RF communications.In this thesis, the implementation process has been performed in MATLABsimulations where we analyse different modulation techniques and parameters. We design a room withdimensions as 5m*5m*3m as length, width and height. We take multiple LED’s at the top and determinethe illumination parameters in the room due to the light emitted from the LED. The receiver is located ona desk and we calculate the number of data rates received at the receiver. The modulation techniques usedin this thesis are OOK keying modulation. We estimate the data rates in two methodologies directdetection (Line of sight) and also, we take reflections from the wall into consideration (Non-line of sight).The effect of data rates due to illumination and distance are also determined. In this thesis we transfer dataover the transmitter and receive the information at the receiver for obtained information the calculation of bit error rate (BER) is performed for both single LED and multiple LED array. The analysis is performed between the performance metrics of a single LED’s and multiple LED’s arrays to determine better-LEDarray.Key Words: OOK modulation scheme, MATLAB-Simulation, Light Emitting Diodes .

Please read the abstract in the section front of this document / Thesis (PhD)--University of Pretoria, 2009. / Electrical, Electronic and Computer Engineering / Unrestricted

Este trabalho propõe a análise da comunicação sem fio para um sistema de controle distribuído de semáforos, a partir da revisão das literaturas, realização de simulações e experimentos, os quais consideram as especificações estabelecidas para o sistema de semáforos. As simulações e os experimentos se baseiam na avaliação do comportamento da comunicação perante a alteração de alguns parâmetros de configuração da rede. O estudo apresentado envolve análises relacionadas ao padrão IEEE 802.11g e às definições da camada física apresentadas nas especificações do padrão. Os métodos utilizados envolvem o estudo e experimentação de parâmetros relacionados à potência de transmissão e recepção, além de análise dos esquemas de modulação utilizados pelo padrão IEEE 802.11g. A metodologia aplicada a este trabalho envolve o conhecimento das características e capacidade dos esquemas de modulação responsáveis pela definição das taxas de transmissão. As análises mostram que a possibilidade de adequação dos parâmetros de configuração de rede, levando em consideração o cenário de aplicação, pode ser um fator essencial para o bom desempenho de todo o sistema. / This work proposes the analysis of wireless communication for a distributed control system of traffic lights, from the review of the literature and conducting simulations and experiments, which consider the specifications established for traffic light system. The simulations and experiments are based on the evaluation of the communication behavior towards changing some network configuration parameters. The study presented involves analysis related to the IEEE 802.11g standard and definitions of the physical layer shown in standard specifications. The methods used involve the study and testing of parameters related to power transmission and reception, and analysis of modulation schemes used by the IEEE 802.11g standard. The methodology applied to this work involves the knowledge of the characteristics and capacity of modulation schemes responsible for setting transmission rates. The analyses show that the possibility of adaptation network configuration parameters considering the application scenario may be an essential factor to the performance of the entire system.

Este trabalho propõe a análise da comunicação sem fio para um sistema de controle distribuído de semáforos, a partir da revisão das literaturas, realização de simulações e experimentos, os quais consideram as especificações estabelecidas para o sistema de semáforos. As simulações e os experimentos se baseiam na avaliação do comportamento da comunicação perante a alteração de alguns parâmetros de configuração da rede. O estudo apresentado envolve análises relacionadas ao padrão IEEE 802.11g e às definições da camada física apresentadas nas especificações do padrão. Os métodos utilizados envolvem o estudo e experimentação de parâmetros relacionados à potência de transmissão e recepção, além de análise dos esquemas de modulação utilizados pelo padrão IEEE 802.11g. A metodologia aplicada a este trabalho envolve o conhecimento das características e capacidade dos esquemas de modulação responsáveis pela definição das taxas de transmissão. As análises mostram que a possibilidade de adequação dos parâmetros de configuração de rede, levando em consideração o cenário de aplicação, pode ser um fator essencial para o bom desempenho de todo o sistema. / This work proposes the analysis of wireless communication for a distributed control system of traffic lights, from the review of the literature and conducting simulations and experiments, which consider the specifications established for traffic light system. The simulations and experiments are based on the evaluation of the communication behavior towards changing some network configuration parameters. The study presented involves analysis related to the IEEE 802.11g standard and definitions of the physical layer shown in standard specifications. The methods used involve the study and testing of parameters related to power transmission and reception, and analysis of modulation schemes used by the IEEE 802.11g standard. The methodology applied to this work involves the knowledge of the characteristics and capacity of modulation schemes responsible for setting transmission rates. The analyses show that the possibility of adaptation network configuration parameters considering the application scenario may be an essential factor to the performance of the entire system.

Un système de transport ferroviaire intelligent est essentiellement caractérisé par son niveau d'autonomie de prise de décision en fonction des conditions qui lui sont extérieurs. Afin de renforcer son intelligence et son autonomie, cette nouvelle génération de systèmes de transport intègre des multiples technologies et standards de communication et de traitement de l'information. L'intégration de ces technologies permet aux opérateurs du transport ferroviaire de réduire les coûts d'exploitation et de maintenance et d'attirer un plus grand nombre de passagers en leur facilitant l'accès ainsi que l'exploitation du transport ferroviaire tout en leur offrant des nouveaux services à bord. Cependant l'utilisation de plusieurs standards de communication ainsi que l'augmentation du trafic (le nombre de passagers et le nombre de véhicules mis en service) déclenchent un besoin sans précédent des ressources radio, notamment au niveau du spectre fréquentiel. En effet, avec la demande croissante des ressources radio, la Radio Intelligente (RI) se présente comme une technologie émergente qui améliore les performances des systèmes radio existants en intégrant l'intelligence artificielle avec la radio logicielle. / Any intelligent railway transport system is mainly characterized by its autonomy in making decisions in terms of its external conditions. In order to improve its cognition and autonomy, this new generation of transport systems integrates multiple technologies and standards of communication and information processing. The integration of these technologies allows rail operators to reduce operational and maintenance costs and attracts more passengers by making easier rail transport access and use while offering new services on board. However, using multiple communication standards and increasing traffic (number of passengers and vehicles in service) trigger an unprecedented need for radio resources, particularly frequency spectrum. Indeed, with the growing of radio resources demand, Cognitive Radio (CR) is an emerging technology that improves the performance of existing radio systems by the integration of artificial intelligence and software defined radio (SDR).

Optimising the throughput performance for wireless networks is one of the challenging tasks in the objectives of communication engineering, since wireless channels are prone to errors due to path losses, random noise, and fading phenomena. The transmission errors will be worse in a multihop scenario due to its accumulative effects. Network Coding (NC) is an elegant technique to improve the throughput performance of a communication network. There is the fact that the bit error rates over one modulation symbol of 16- and higher order- Quadrature Amplitude Modulation (QAM) scheme follow a certain pattern. The Scattered Random Network Coding (SRNC) system was proposed in the literature to exploit the error pattern of 16-QAM by using bit-scattering to improve the throughput of multihop network to which is being applied the Random Linear Network Coding (RLNC). This thesis aims to improve further the SRNC system by using Forward Error Correction (FEC) code; the proposed system is called Joint RLNC and FEC with interleaving. The first proposed system (System-I) uses Convolutional Code (CC) FEC. The performances analysis of System-I with various CC rates of 1/2, 1/3, 1/4, 1/6, and 1/8 was carried out using the developed simulation tools in MATLAB and compared to two benchmark systems: SRNC system (System-II) and RLNC system (System- III). The second proposed system (System-IV) uses Reed-Solomon (RS) FEC code. Performance evaluation of System IV was carried out and compared to three systems; System-I with 1/2 CC rate, System-II, and System-III. All simulations were carried out over three possible channel environments: 1) AWGN channel, 2) a Rayleigh fading channel, and 3) a Rician fading channel, where both fading channels are in series with the AWGN channel. The simulation results show that the proposed system improves the SRNC system. How much improvement gain can be achieved depends on the FEC type used and the channel environment.

Optimising the throughput performance for wireless networks is one of the challenging tasks in the objectives of communication engineering, since wireless channels are prone to errors due to path losses, random noise, and fading phenomena. The transmission errors will be worse in a multihop scenario due to its accumulative effects. Network Coding (NC) is an elegant technique to improve the throughput performance of a communication network. There is the fact that the bit error rates over one modulation symbol of 16- and higher order- Quadrature Amplitude Modulation (QAM) scheme follow a certain pattern. The Scattered Random Network Coding (SRNC) system was proposed in the literature to exploit the error pattern of 16-QAM by using bit-scattering to improve the throughput of multihop network to which is being applied the Random Linear Network Coding (RLNC). This thesis aims to improve further the SRNC system by using Forward Error Correction (FEC) code; the proposed system is called Joint RLNC and FEC with interleaving. The first proposed system (System-I) uses Convolutional Code (CC) FEC. The performances analysis of System-I with various CC rates of 1/2, 1/3, 1/4, 1/6, and 1/8 was carried out using the developed simulation tools in MATLAB and compared to two benchmark systems: SRNC system (System-II) and RLNC system (System- III). The second proposed system (System-IV) uses Reed-Solomon (RS) FEC code. Performance evaluation of System IV was carried out and compared to three systems; System-I with 1/2 CC rate, System-II, and System-III. All simulations were carried out over three possible channel environments: 1) AWGN channel, 2) a Rayleigh fading channel, and 3) a Rician fading channel, where both fading channels are in series with the AWGN channel. The simulation results show that the proposed system improves the SRNC system. How much improvement gain can be achieved depends on the FEC type used and the channel environment. / Indonesian Government and the University of Bradford