Multi-Hop Wireless Optical Backhauling for LiFi Attocell Networks: Bandwidth Scheduling and Power Control

The backhaul of hundreds of light fidelity (LiFi) base stations (BSs) constitutes a major challenge. Indoor wireless optical backhauling is a novel approach whereby the interconnections between adjacent LiFi BSs are provided by way of directed line-of-sight (LOS) wireless infrared (IR) links. Building on the aforesaid approach, this paper presents the top-down design of a multi-hop wireless backhaul configuration for multi-tier optical attocell networks by proposing the novel idea of super cells. Such cells incorporate multiple clusters of attocells that are connected to the core network via a single gateway based on multi-hop decode-and-forward (DF) relaying. Consequently, new challenges arise for managing the bandwidth and power resources of the bottleneck backhaul. By putting forward user-based bandwidth scheduling (UBS) and cell-based bandwidth scheduling (CBS) policies, the system-level modeling and analysis of the end-to-end multi-user sum rate is elaborated. In addition, optimal bandwidth scheduling under both UBS and CBS policies are formulated as constrained convex optimization problems, which are solved by using the projected subgradient method. Furthermore, the transmission power of the backhaul system is opportunistically reduced by way of an innovative fixed power control (FPC) strategy. The notion of backhaul bottleneck occurrence (BBO) is introduced. An accurate approximate expression of the probability of BBO is derived, and then verified using Monte Carlo simulations. Several insights are provided into the offered gains of the proposed schemes through extensive computer simulations, by studying different aspects of the performance of super cells including the average sum rate, the BBO probability and the backhaul power efficiency (PE).Comment: 36 pages, 21 figures, 1 tabl

Evaluación de la tecnología Small Cells en una red de última generación 3G/LTE

The growing demand to mobile operators for better data service in addition to the upward rise in consumption of mobile data, generate the need to find practical solutions that help mobile operators to handle these problems. This thesis presents the implementation and characterization of a Small Cell, an indoor solution installed in the network of an operator in the country and tested in the city of Guayaquil. A general context of this solution was first shown in this project to understand the generalities of a Small Cell indoor solution. Then we introduce a methodology part in which we explain the tests performed to this equipment and how we should run these tests, plus the implementation stages required to perform the proper installation of this indoor solution in a building. Finally we present the practical phase in which we detailed each step taken in the installation of a Small Cell, along with an analysis of the tests on which it will be seen that the Small Cell produces improved mobile data download and becomes a viable and ideal indoor solution for the client that can be implemented in our country.  La creciente demanda de un mejor servicio de datos hacia las operadores móviles además de la ascendente alza en el consumo de datos móviles del cliente, generan la necesidad de encontrar soluciones prácticas que ayuden a los operadores a manejar estos problemas. En esta tesis se presenta la implementación y cateterización de una solución indoor Small Cell que se realizó en la red de un operador del país en un sitio de prueba dentro de la ciudad de Guayaquil. Se muestra primero un contexto general de esta solución para entender las generalidades y de que se trata la misma para luego mostrar una parte de metodología en la que se explican las pruebas que pueden realizarse y cómo se deben ejecutar estas pruebas, además de las etapas de implementación para conseguir la instalación adecuada de este equipo. Por último se muestra la fase práctica en la que se detalla las etapas y cada paso realizado en la instalación de una Small Cell, además de un análisis de las pruebas en las que se ven que la Small Cell produce una mejora en la descarga de datos y se coloca como una solución indoor viable e ideal para el cliente

A guide to wireless networking by light

The lack of wireless spectrum in the radio frequency bands has led to a rapid growth in research in wireless networking using light, known as LiFi (light fidelity). In this paper an overview of the subsystems, challenges and techniques required to achieve this is presented

Performance Analysis of Coexistence Schemes for LTE in Unlicensed Bands

LTE in the unlicensed spectrum, is becoming a popular area of research. Since LTE-Unlicensed (LTE-U) provides subscribers with higher-quality mobile voice, and video experience in high-traffic or low-signal locations, a fair coexistence mechanism with other networks, like Wi-Fi is essential. In this thesis, we propose two coexistence mechanisms that could be employed to ensure a fair channel access. First, we consider coexistence mechanism fundamentals, and then downlink system performance of two coexistence mechanisms are analyzed for multi-operator LTE-Unlicensed (LTE-U) deployments with different simulation scenarios, using NS-3. First we introduce the most trustworthy coexistence mechanism, and then a high-performance coexistence scenario is provided. We conclude that Licensed Assisted Access (LAA) can coexist with Wi-Fi without impacting Wi-Fi more than an equivalent Wi-Fi network. In the second part, uplink performance evaluation of LTE in licensed spectrum is also demonstrated

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

Indoor cooperative small cells over ethernet

The ubiquitous Ethernet has great potential to become an easy-to-install cost-effective backhaul solution for mobile small cells. However, limited Ethernet bandwidth is a practical constraint. Not only is small cell capacity limited by Ethernet bandwidth, but also the synchronization between cells can be substantially compromised. In this article we discuss small cells with Ethernet backhaul, focusing on two practical and important aspects: backhaul bandwidth requirements and tolerance to synchronization errors. The aspects become challenging in indoor small cell applications where the cells need to cooperatively suppress strong interference, producing a large amount of backhaul traffic. To address the challenges, we introduce a new distributed scheme of cooperative small cells over Ethernet. Exploiting a soft information combining technique, the scheme allows the signals of cooperative cells to be combined at aggregate switches along their backhaul paths, reducing backhaul traffic in Ethernet and distributing computational complexity. Our case study shows that the distributed scheme can reduce small cell backhaul traffic by 64 percent, compared to a conventional centralized approach. It is also tolerant to a large frequency error of ±4.6 ppm in a ¿freerun¿ state where synchronization is lost. Given the substantially reduced backhaul traffic, the new distributed scheme is able to support three times the cooperative small cells of the conventional centralized approach. © 1979-2012 IEEE. © 2013 IEEE