Performance analysis of OFDM technology on radio-over-fiber systems

Dissertação de mest., Engenharia Eletrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011Nowadays, the demand for high speed, high quality and diversity in distributed services presents a challenge for telecommunication technology. Wireless systems provide the accessibility to end-user, but are not the solution for long distance links. Currently, the ideal technology for long-range transmissions at high data rates is optical fiber. Hence, a new concept for high capacity networks emerges, with centralized services into Base Stations (BS) engineered to provide flexibility and control over the system, and to perform operations such as electrical to optical domain conversion and modulation. Such Radio-over-Fiber (RoF) networks also appear as an attractive technology because they are efficient and cost effective. Orthogonal Frequency Division Multiplexing (OFDM) technology is widely used in a number of standards. For instance, it is actually the Multi-Carrier Modulation (MCM) technique applied in 802.11a/g/n wireless standards and in Digital Video Broadcasting-Terrestrial (DVB-T), among other prevailing systems, which makes this subject one particularly pertinent to study. OFDM systems are an appealing choice for waveform modulation, as they are very bandwidth efficient comparing to others MCM, and provide flexibility in data transmission rates. Additionally, an important advantage dwells in its natural robustness against severely interfering environments. In this thesis, fundamentals on OFDM technology are extensively described, and its application to wireless and optical fiber networks is introduced. The combined channel effects of these technologies on OFDM signals are investigated. In terms of performance analysis, this exposition focuses on understanding the importance of OFDM modulation parameters, and explores some OFDM signal properties. To achieve this, a simulator was implemented with Matlab to create arbitrary OFDM waveforms and emulate channel effects. This study also investigates the efficiency of OFDM technology over a real Radio Frequency (RF) system with an ideal communication channel. Finally, an experimental RoF configuration is implemented and its performance is assessed

The Four-C Framework for High Capacity Ultra-Low Latency in 5G Networks: A Review

Network latency will be a critical performance metric for the Fifth Generation (5G) networks expected to be fully rolled out in 2020 through the IMT-2020 project. The multi-user multiple-input multiple-output (MU-MIMO) technology is a key enabler for the 5G massive connectivity criterion, especially from the massive densification perspective. Naturally, it appears that 5G MU-MIMO will face a daunting task to achieve an end-to-end 1 ms ultra-low latency budget if traditional network set-ups criteria are strictly adhered to. Moreover, 5G latency will have added dimensions of scalability and flexibility compared to prior existing deployed technologies. The scalability dimension caters for meeting rapid demand as new applications evolve. While flexibility complements the scalability dimension by investigating novel non-stacked protocol architecture. The goal of this review paper is to deploy ultra-low latency reduction framework for 5G communications considering flexibility and scalability. The Four (4) C framework consisting of cost, complexity, cross-layer and computing is hereby analyzed and discussed. The Four (4) C framework discusses several emerging new technologies of software defined network (SDN), network function virtualization (NFV) and fog networking. This review paper will contribute significantly towards the future implementation of flexible and high capacity ultra-low latency 5G communications

Recent Advances in Wireless Communications and Networks

This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters