In modern life, there are many applications where positioning plays an important role. People have developed the global positioning system (GPS) to locate world wide position with error in decameter scales, which brings people much convenience. However, the accuracy of GPS is too low for indoor localization. The signals will drop down due to the signal attenuation caused by construction materials. With the well-developed GPS being indispensable for outdoor activities, many researchers have been also devoted to seeking an indoor positioning system to realize indoor localization with acceptable error. Indoor localization can be very useful in different situations, like locating, tracking, navigation and identification. For example, in the mall, locating the exact goods for customers can provide much convenience and benefits. Locating and tracking in the airport can greatly help passengers save their time and energy in reaching the destination. In another general scenario of identification, the population of observed targets is usually larger than just one. Hence, only with small error, indoor localization system (ILS) can be able to identify the targets despite the neighbors. Due to the emerging and urging demands of increasing the accuracy of indoor localization, we propose a novel design of three dimensional (3-D). optical receiver for visible light communication (VLC) indoor positioning system. First, we model the optical wireless channel. Then we utilize modified triangulation method to obtain more robust receiver position by using at least two light-emitting diodes (LEDs) and one receiver consisting of nine photodetectors (PDs). Finally, the improved algorithm is implemented and the results are shown under our three dimensional multiple photodetectors (multi-PDs) structure receiver. In the simulation, we take the parameters of Lambertian radiation pattern, LEDs and PDs as those shown in [1] . To be noticed, our design of multi-PDs receiver is fully expanded into three dimensions compared with the pyramid receiver (PR), which allows indoor positioning with our receiver structure to be more robust to the higher or corner positions. The details will be explained in the following sections. Based on Multiple-Photodiodebased Indoor Positioning algorithm [1], the indoor positioning algorithm is improved by redefining the optimization problem of obtaining the direction from receiver to LED and using weighted triangulation method to locate receiver position. We admit the solution under the redefined problem is not optimal to the actual problem. Yet, our given solution is better to that in [1] due to the existence of noise, which is reasonable and has been verified.

The field of Optical Wireless Communications (OWC) has seen rapid development during the recent years. This growing popularity is due to several characteristics of considerable importance to consumer electronics products, such as large bandwidth that is also not having spectrum regulations imposed, low cost, and license free operation. As a branch of OWC, visible light communication (VLC) systems have their own unique advantages, with several new technologies, products and patents having been developed during since the end of last century. In this research, a VLC system for indoor application is proposed. In this work, we focus on reducing cost, and for that, we had to make appropriate selection of system’s components, e.g. modulation, coding, filtering. Our objective was to achieve acceptable bit error rate (BER) performance for indoor use, with a low cost system. Through our research we met this objective. Our designs were evaluated through computer simulations. The acquired results proved the suitability of the proposed schemes and the performance’s degree of dependency on several parameters such as distance, incidence angle and irradiance angle. A software tool was created allowing easy assessment of the communication system. It is using a user friendly GUI through which the user enters the system’s parameters and the system outputs the corresponding BER value.

The field of Optical Wireless Communications (OWC) has seen rapid development during the recent years. This growing popularity is due to several characteristics of considerable importance to consumer electronics products, such as large bandwidth that is also not having spectrum regulations imposed, low cost, and license free operation. As a branch of OWC, visible light communication (VLC) systems have their own unique advantages, with several new technologies, products and patents having been developed during since the end of last century. In this research, a VLC system for indoor application is proposed. In this work, we focus on reducing cost, and for that, we had to make appropriate selection of system’s components, e.g. modulation, coding, filtering. Our objective was to achieve acceptable bit error rate (BER) performance for indoor use, with a low cost system. Through our research we met this objective. Our designs were evaluated through computer simulations. The acquired results proved the suitability of the proposed schemes and the performance’s degree of dependency on several parameters such as distance, incidence angle and irradiance angle. A software tool was created allowing easy assessment of the communication system. It is using a user friendly GUI through which the user enters the system’s parameters and the system outputs the corresponding BER value.

The field of Optical Wireless Communications (OWC) has seen rapid development during the recent years. This growing popularity is due to several characteristics of considerable importance to consumer electronics products, such as large bandwidth that is also not having spectrum regulations imposed, low cost, and license free operation. As a branch of OWC, visible light communication (VLC) systems have their own unique advantages, with several new technologies, products and patents having been developed during since the end of last century. In this research, a VLC system for indoor application is proposed. In this work, we focus on reducing cost, and for that, we had to make appropriate selection of system’s components, e.g. modulation, coding, filtering. Our objective was to achieve acceptable bit error rate (BER) performance for indoor use, with a low cost system. Through our research we met this objective. Our designs were evaluated through computer simulations. The acquired results proved the suitability of the proposed schemes and the performance’s degree of dependency on several parameters such as distance, incidence angle and irradiance angle. A software tool was created allowing easy assessment of the communication system. It is using a user friendly GUI through which the user enters the system’s parameters and the system outputs the corresponding BER value.

Light-emitting diode (LED) luminaires are ubiquitous and widely used in our daily life. Because of energy efficiency and illumination requirements, LED lamps are required to dim. In addition to the lighting function, visible light communication (VLC) is being considered as a potential technology beyond 5G. Orthogonal frequency-division multiplexing (OFDM) is a popular modulation choice and most recently spatial optical OFDM (SO-OFDM) has been used with multiple LEDs. SO-OFDM is a low complexity way of constructing OFDM signals by sending a series of narrow-band emissions from different LEDs and allowing them to sum in space. The integration of dimming within an SO-OFDM framework remains an open area of research. In this thesis, an optimal dimming strategy for optical power allocation is proposed based on SO-OFDM in visible light communication systems under different illumination requirements, i.e., dimming. Firstly, a non-convex problem is formulated to maximize the capacity of SO-OFDM under a specified dimming target. Furthermore, this non-convex problem is broken into a group of convex problems through approximations and constraint relaxation. The proposed scheme can optimize the power allocation in SO-OFDM and achieve the dimming target at the same time. According to the proposed power allocation scheme, more of the power is allocated to subcarriers with low noise variance. This phenomenon makes sense to take advantage of good channels when power is limited and is similar to the conventional water-filling method. When the dimming target and signal-to-noise ratio (SNR) is sufficiently high, the optimal distribution approaches a uniform distribution that agrees well with conventional water filling in a high SNR regime. Compared with traditional digital dimming, the proposed spatial dimming method can not only use spatial domain for dimming but also allocates power to different subcarriers according to channel conditions which is more efficient. Analytical and numerical results imply that the proposed scheme converges quickly and performs well compared with traditional power allocation methods. / Thesis / Master of Applied Science (MASc)

Low-infrastructure techniques for indoor localization attempt to provide indoor positioning information for users, without requiring the installation of specialized transmitting or receiving hardware. Such an approach should encourage further adoption of indoor positioning systems by reducing the installation burden on individual building owners. If fully adopted, indoor positioning could prove to be a valuable addition to the existing outdoor localization system based on GPS. In this work, a particle filter is used to combine motion and light data in order to provide positioning information for a user in an indoor environment. A simple lighting model is used to predict light measurements, while an orientation tracking algorithm provides information about user motion. The system is shown to work with the existing lighting infrastructure of a building, though the addition of visible light communication (VLC) enabled light fixtures is shown to further improve performance. An experimental demonstration of the proposed system is provided, which indicates that tracking accuracy on the order of ten’s of centimetres is possible with very low infrastructure requirements. / Thesis / Master of Applied Science (MASc)

Wireless communication is a form of communication that has been around for over hundreds of years and is the fastest growing segment of the communication industry. Today, wireless communication has become an essential part of almost everyone’s daily life, and the number of users has increased exponentially over the last decade with the introduction of the internet, mobile devices and smart phones. Radio Frequency (RF) transmission is arguably the most popular method of communication and is available worldwide. With the rapid progress in technology and the increase of number of users, the limited RF spectrum is becoming more congested which led to numerous research efforts to find an alternative that can help to alleviate the pending problem. One of the proposed solutions is Visible Light Communication (VLC), which uses visible Light Emitting Diode (LED) for data transmission. In this thesis, three integrated microLED/Complementary Metal Oxide Semiconductor (CMOS) Integrated Circuits (ICs) are presented with the main aim of increasing the data rate of transmission. The first microLED/CMOS IC presented here is the Generation V microLED/CMOS driver which represents the continuation of the earlier work in the HYPIX project, which aimed to develop a microLED/CMOS driver to optically pump an organic polymer laser. A 40x10 pixelarray of Generation V microLED/CMOS driver was thus designed, primarily for optical pumping polymer lasing purposes, but has also demonstrated the ability to perform communication transmission using an On-Off Keying (OOK) modulation scheme. The driver consumes up to 330mA current and produces approximately 12mW of optical power from a single pixel, which is about 3 times higher than its predecessor. The second microLED/CMOS IC is the microLED/CMOS Current Feedback (CCFBK) driver which was designed to facilitate Orthogonal Frequency Division Multiplexing (OFDM) modulation. OFDM is one of the modulation schemes, adopted from the RF domain, that was proposed to be implemented in VLC in order to increase the data transmission rate. To the best of the author’s knowledge, the microLED/CCFBK driver is the first CMOS driver for microLED that was designed to perform analogue modulation for VLC purposes. The driver is characterised and shows the ability to produce up to 3.5mW of optical power with a data transmission rate of up to 486Mbit/s. The microLED/CMOS Optical Feedback (COFBK) driver is the third microLED/CMOS IC presented in this thesis. The driver looks to improve on the performance of the microLED/CCFBK driver. OFDM transmission requires high linearity to ensure low Bit Error Rate (BER) transmission. However, the optical power output of an LED is not, in general, linear with the input voltage signal. The microLED/COFBK driver looks to increase the linearity of the optical power output by integrating a microLED and a photodiode in a single pixel to create a feedback loop. Once again, to the best of the author’s knowledge, the microLED/COFBK driver is the first CMOS driver for microLED which integrates both optical source and sensor in a single pixel to help linearise the optical power output for communication purposes; in this case, VLC. For a similar range of optical power, the microLED/COFBK driver shows a reduction about 5.3% in the degree of non-linearity compared to the microLED/CCFBK driver and produces lower Total Harmonic Distortion (THD). The microLED/COFBK driver showed the potential to increase the data rate by a factor of four over that of microLED/CCFBK driver. The analogue modulated microLED/CMOS ICs described here are the first-generation drivers that have demonstrated the possibilities to increase the data rate using OFDM. A number of possible design improvements have been identified which will enhance future performance and integration with the standard VLC system.

This thesis is focused on the use of light and LEDs for communication between the light and the user. In the introduction, the principles of VLC, which Li-Fi is part of, are described. The work also contains issues on the topics of Li-Fi, such as methods of modulation of carrier signals for data transmission, comparisons between other wireless communications, individual elements of optical frontends, current versions of Li-Fi and other possible uses of this technology. The work also contains the designing of a system working on the principle of Li-Fi.

I takt med att efterfrågan på trådlös kommunikation med hög hastighet ökar och det ökande antalet enheter som är trådlöst anslutna har forskare börjat utforska kompletterande teknologier. Hybridnätverk bestående av LiFi och WiFi är en kombination av Light-Fidelity och Wireless-Fidelity som kombinerar dataöverföring över både radiovågor och ljus. Hybridnätverk med LiFioch WiFi är ett lovande system där hastigheter över 10 Gbps är möjliga och teknikerna inte kan störa ut varandra. Den systematiska litteraturstudie som genomförts syftade till att kartlägga fördelar, nackdelar och utmaningar vid implementationen av dessa hybridnätverk. Sökningar efter litteratur för studien gjordes i fem olika databaser med hjälp av en specifik sökterm, vilket resulterade i 43 accepterade artiklar. En kvalitativ metod, tematisk kodning, användes för att hitta svaren, vilket resulterade i att 20 subteman identifierades spridda över de tre olika huvudteman. Analysen visade att den mest frekvent rapporterade fördelen var prestanda, den vanligaste nackdelen var handover och den mest framträdande utmaningen var load balancing. / With the increasing demand for high-speed wireless communication and the growing numberof devices connected wirelessly, researchers have started exploring complementary technologies. Hybrid LiFi and WiFi networks are a combination of Light-Fidelity and Wireless-Fidelity, which combine data transmission over Radio Frequency and light. Hybrid LiFi and WiFi networks are a promising system that offers speeds above 10 Gbps without interference from one another. The conducted systematic literature review aimed to discover the advantages, disadvantages, and challenges of implementing a hybrid LiFi and WiFi network. The search for literature was conducted in five different databases using one search term, resulting in 43 accepted articles. A qualitative approach using thematic coding was conducted to find the answers, resulting in 20 sub-themes divided over the three main themes. The analysis showed that the most frequently reported advantage was performance, the most common disadvantage was handover, and the most appearing challenge was load balancing.

This thesis presents the design and implementation of the pipeline architecture of H.264/AVC video decoder. The H.264 video compression standard is one of the emerging standards proposed by Joint Video Team (JVT), which can provide high compression ratio and good rate distortion efficiency. It adopts smaller block size and finer motion vector resolution to achieve better predicted motion compensated pictures. While the compression ratio is greatly improved, the computational complexity also increases a lot. How to design the efficient H.264 decoder has become an important topic. This thesis first addresses the design issue of the individual module, and several good architectural solutions are proposed. For the design of the interpolation module, a novel interpolator architecture which can dynamically configure the datapath to perform different computation schedules suitable for the input order of reference samples is proposed. The resulted architecture not only reduces the hardware requirement, but most importantly the communication time spent to move the reference data can be overlapped with the computation time of the predicted samples. Our experimental result shows that the proposed interpolator can achieve 40% average cycle reduction with less hardware cost. For the design of deblocking filter, the thesis also proposes a novel schedule which interleaves the operation of row and column filtering that can lead to a low-cost deblocking filter based on the single-port memory. For the design of variable length decoder, this thesis proposes a new table partitioning method to reduce the overall table size. Finally, all the individual modules are further integrated in the pipelining fashion to increase the overall decoding throughput. The minimum pipelining unit between different stages used in the proposed decoder is the 4x4 block such the memory buffer required can be greatly reduced. The proposed architecture can perform the real-time decoding of video at the resolution of 640x480 pixels.