We are presenting an overview of MEMS-based (Micro-Electro-Mechanical System) optical switch technology starting from the reflective two-dimensional (2D) and three-dimensional (3D) MEMS implementations. To further increase the speed of the MEMS from these devices, the mirror size needs to be reduced. Small mirror size prevents efficient reflection but favors a diffraction-based approach. Two implementations have been demonstrated, one using the Texas Instruments DLP (Digital Light Processing), and the other an LCoS-based (Liquid Crystal on Silicon) SLM (Spatial Light Modulator). These switches demonstrated the benefit of diffraction, by independently achieving high speed, efficiency, and high number of ports. We also demonstrated for the first time that PSK (Phase Shift Keying) modulation format can be used with diffraction-based devices. To be truly effective in diffraction mode, the MEMS pixels should modulate the phase of the incident light. We are presenting our past and current efforts to manufacture a new type of MEMS where the pixels are moving in the vertical direction. The original structure is a 32 x 32 phase modulator array with high contrast grating pixels, and we are introducing a new sub-wavelength linear array capable of a 310 kHz modulation rate.

M.Ing. / Please refer to full text to view abstract

The subject of this thesis concerns conversion between the interfaces specified by CCITT recommendations X.21 and V.24. The evolution of public data networks against the background of data communications using the telephone network is outlined. The DTE/DCE interface is identified as being of particular importance and is explained in terms of the ISO model for Open Systems interconnection (OSI). CCITT recommendation X.21 is described in detail using the OSI layered approach. Finite state machine (FSM) terminology is defined and the concept of an interface machine introduced. CCITT recommendation V.24 is described in terms of the physical layer of the OSI model. Only those aspects of V.24 relevant to the subject of this thesis are examined. Interface conversion between X.21 and V.24 is discussed in detail and the design of devices to perform the conversion described. A microprocessor-based translator to perform interface conversion between a V.24 DTE and a X.21 DCE for switched circuit use is designed, using the FSM approach. A preliminary model of such a translator, implemented on a development system, is described. Its hardware and software are outlined and areas for further work identified.

I dagens läge är industriella nätverk inte anpassade för att koppla upp resursbegränsade enheter pga av att industriella nätverks-protokollen som används är mer anpassade för real time applikationer. Det skulle vara ett stort steg för de industriella nätverken att kunna koppla upp resursbegränsade enheter för enkel övervakning samt analysering av data. Efter en undersökningsperiod av ett flertal olika IoT-protokoll, gjordes valet att implementera CoAP på en Anybus CompactCom-modul för testning. Under projektets gång användes det en del white-box testning i början vid implementationen av libCoAP. Efter att en fungerande implementation var gjord, påbörjades testning av input och output överensstämmelser med hjälp av black-box testning istället. Resultatet jämfördes i slutändan med den existerande lösningen att skicka parameterdata med hjälp av TCP. Resultatet hade en responstidsskillnad som var 92,3 % snabbare. Samtidigt tog det sammanlagt 24,2 % mindre plats i minnet (FLASH och RAM) för implementationen på Anybus CompactCom-modulen.

The monitoring of animal control devices (animal traps) in remote areas currently requires field workers to visit each device on a regular basis, which is costly and time consuming. Better monitoring practices could allow DOC to increase their trapping practices through reduced costs. Essentially, the aim of this paper is to reduce the number of man-hours, and hence resources, required to check each trap. An attempt will be made to use wireless communications to check the status of each trap, and hence decide whether or not it will need to be checked, bringing benefits of efficiency and cost savings to the Department of Conservation. It is recognised that the environment is very difficult for traditional wireless communications to operate reliably and therefore new methods or technologies were investigated for this application. A system operating at 27MHz using a modified pulse position modulation scheme was found to be an appropriate solution; however the success of wireless communications in pest control management is dependent upon the trapping location, patterns and terrain.

<p>With the ever increasing demand for data communication methods, power line communication has become an interesting alternative method for data communication. Power line communication falls into two categories: one for data transmission between sites in the power grid and the other for home or office networking. When considering home or office networking, existing methods are either too slow for tasks other than simple automation, or are very fast with a higher cost than necessary for the desired function. The objective in this work is to develop a lower cost communication system with an intermediate data transmission rate.</p><p>At first glance, power line communication looks like a good option because of the availability of power outlets in every room of a building. However, the power conductors were installed solely for the purpose of distributing 60 Hz mains power and, for data signals, they exhibit very high attenuation, variable impedance and there is radio frequency shielding. Furthermore, many of the 60 Hz loads produce radio frequency interference that impedes data communication. Previous research has shown that much of the noise is time synchronous with the 60 Hz mains frequency and that the majority of data errors occur during these periods of high noise.</p><p> This work develops a power line communication protocol that coordinates transmissions and uses only the predictable times of lower noise. Using a central control strategy, the power line 60 Hz mains signal is divided into 16 timeslots and each timeslot is monitored for errors. The central controller periodically polls all stations to learn which timeslots have low noise and it then controls all transmissions to make the best use of these good timeslots. The periodic polling allows the system to adapt to changes in electrical loading and noise. This control strategy has been achieved with modest complexity and laboratory measurements have shown throughput approaching 70% of the modem bit rate.</p>

<p>With the ever increasing demand for data communication methods, power line communication has become an interesting alternative method for data communication. Power line communication falls into two categories: one for data transmission between sites in the power grid and the other for home or office networking. When considering home or office networking, existing methods are either too slow for tasks other than simple automation, or are very fast with a higher cost than necessary for the desired function. The objective in this work is to develop a lower cost communication system with an intermediate data transmission rate.</p><p>At first glance, power line communication looks like a good option because of the availability of power outlets in every room of a building. However, the power conductors were installed solely for the purpose of distributing 60 Hz mains power and, for data signals, they exhibit very high attenuation, variable impedance and there is radio frequency shielding. Furthermore, many of the 60 Hz loads produce radio frequency interference that impedes data communication. Previous research has shown that much of the noise is time synchronous with the 60 Hz mains frequency and that the majority of data errors occur during these periods of high noise.</p><p> This work develops a power line communication protocol that coordinates transmissions and uses only the predictable times of lower noise. Using a central control strategy, the power line 60 Hz mains signal is divided into 16 timeslots and each timeslot is monitored for errors. The central controller periodically polls all stations to learn which timeslots have low noise and it then controls all transmissions to make the best use of these good timeslots. The periodic polling allows the system to adapt to changes in electrical loading and noise. This control strategy has been achieved with modest complexity and laboratory measurements have shown throughput approaching 70% of the modem bit rate.</p>

Our burgeoning appetite for data relentlessly demands exponential scaling of computing and communications resources leading to an overbearing and ever-present drive to improve efficiency while reducing on-chip area even as photonic components expand to fill application spaces no longer satisfied by their electronic counterparts. With a high index contrast, low optical loss, and compatibility with the CMOS fabrication infrastructure, silicon-on-insulator technology delivers a mechanism by which efficient, sub-micron waveguides can be fabricated while enabling monolithic integration of photonic components and their associated electronic infrastructure. The result is a solution leveraging the superior bandwidth of optical signaling on a platform capable of delivering the optical analogue to Moore's Law scaling of transistor density. Device size is expected to end Moore's Law scaling in photonics as Maxwell's equations limit the extent to which this parameter may be reduced. The focus of the work presented here surrounds photonic device miniaturization and the development of 3D optical interconnects as approaches to optimize performance in densely integrated optical interconnects. In this dissertation, several technological barriers inhibiting widespread adoption of photonics in data communications and telecommunications are explored. First, examination of loss and crosstalk performance in silicon nitride over SOI waveguide crossings yields insight into the feasibility of 3D optical interconnects with the first experimental analysis of such a structure presented herein. A novel measurement platform utilizing a modified racetrack resonator is then presented enabling extraction of insertion loss data for highly efficient structures while requiring minimal on-chip area. Finally, pioneering work in understanding the statistical nature of doublet formation in microphotonic resonators is delivered with the resulting impact on resonant device design detailed.

The aim of this thesis was to create a resilient network, capable of handling link failures without affecting the data flow. This was done by using graph theory and three mathematical models. A generic system was created, on which the models were applied on. The mathematical models were path diversity, edge protection and path restoration. These models were tested to evaluate if they could create a robust system. The models were also compared with each other to obtain the best performing one. It was concluded that it was possible to construct a resilient network using these types of mathematical modelling. It was also concluded that the models provided different results in terms of cost and robustness. The report ends with suggestions on future work of how studies can be conducted to create realistic systems.

In the context of location, large amounts of information are available on the Internet to be accessed by people via different devices. However, at times people have to manually search and access it. If the space where location-based services are available can be identified by hand-held devices, people can be prompted with services available around them. This thesis explores the use of ultrasound as a communication medium to tag such spaces and access location-based services with the related information; and demonstrates the indoor implementation of the prototype of a location-based services enabling system for hand-held devices. This system allows users to search and access the available services in their surroundings through their hand-held devices. A beacon generator placed in the service location broadcasts a service code mappable to the services particular to that location encoded in an ultrasound signal. The hand-held device can identify this signal and prompt the user with available services. System design and architecture is demonstrated and the viability of the system is tested through a variety of environments and scenarios showing that potentially this has both a wide range of applications and can enhance the way people access location-based services. / Thesis (Master, Computing) -- Queen's University, 2013-01-30 17:50:20.285