An investigation into buffer management mechanisms for the Diffserv assured forwarding traffic class

Includes bibliographical references.One of the service classes offered by Diffserv is the Assured Forwarding (AF) class. Because of scalability concerns, IETF specifications recommend that microflow and aggregate-unaware active buffer management mechanisms such as RIO (Random early detecLion with ln/Out-ofprofile) be used in the core of Diffserv networks implementing AF. Such mechanisms have, however, been shown to provide poor performance with regard to fairness, stability and network controL Furthermore, recent advances in router technology now allow routers to implement more advanced scheduling and buffer management mechanisms on high-speed ports. This thesis evaluates the performance improvements that may be realized when implementing the Diffserv AF core using a hierarchical microflow and aggregate aware buffer management mechanism instead of RIO. The author motivates, proposes and specifies such a mechanism. The mechanism. referred to as H-MAQ or Hierarchical multi drop-precedence queue state Microflow-Aware Quelling, is evaluated on a testbed that compares the performance of a RIO network core with an H-MAQ network core

Enabling Technology in Optical Fiber Communications: From Device, System to Networking

This book explores the enabling technology in optical fiber communications. It focuses on the state-of-the-art advances from fundamental theories, devices, and subsystems to networking applications as well as future perspectives of optical fiber communications. The topics cover include integrated photonics, fiber optics, fiber and free-space optical communications, and optical networking

Fluid flow queue models for fixed-mobile network evaluation

A methodology for fast and accurate end-to-end KPI, like throughput and delay, estimation is proposed based on the service-centric traffic flow analysis and the fluid flow queuing model named CURSA-SQ. Mobile network features, like shared medium and mobility, are considered defining the models to be taken into account such as the propagation models and the fluid flow scheduling model. The developed methodology provides accurate computation of these KPIs, while performing orders of magnitude faster than discrete event simulators like ns-3. Finally, this methodology combined to its capacity for performance estimation in MPLS networks enables its application for near real-time converged fixed-mobile networks operation as it is proven in three use case scenarios

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

Design of a New High Bandwidth Network for Agricultural Machines

Ethernet is by now the most adopted bus for fast digital communications in many environments, from household entertainment to PLC robotics in industrial assembly lines. Even in automotive industry, the interest in this technology is increasingly growing, pushed forward by research and by the need of high throughput that high dynamics distributed control demands. Although 100base-TX physical layer (PHY) does not seem to meet EMC requirements for vehicular and heavy-duty environments, OPEN Alliance BroadR Reach (soon becoming IEEE standard as IEEE 802.3bw) technology is the most promising and already adopted Ethernet-compatible PHY, reaching 100Mbps over an unshielded twisted pair. An agricultural machine is usually a system including tractor and one or more implements attached to it, to the back or to the front. Nowadays, a specific CAN-based distributed control network support treatments and applications, namely ISOBUS, defined by ISO 11783. This work deals with architectural and technological aspects of advanced Ethernet networks in order to provide a high-throughput deterministic network for in-vehicle distributed control for agricultural machinery. Two main paths of investigation will be presented: one concerning the prioritization of standard Ethernet taking advantage of standard ways of prioritization in well-established technologies; the other changing the channel access method of Ethernet using an industrial fieldbus, chosen after careful investigation. The prioritization of standard Ethernet is performed at two, non-mutual exclusive layers of the ISO OSI stack: one at L3, using the diffserv (former TOS) Ip field; one at L2, using the priorities defined in IEEE 802.1p, used in IEEE 802.1q (VLAN). These choices have several implications in the specific field of application of the agricultural machines. The change of the access method, instead, focused on the adoption of a specific fieldbus, in order to grant deterministic access to the medium and reliability of communications for safety-relevant applications. After a survey, that will be reported, the Powerlink fieldbus was chosen and some modifications will be discussed in order to suit the scope of the research