Medium access control mechanisms for high speed metropolitan area networks

In this dissertation novel Medium Access Control mechanisms for High Speed Metropolitan Area networks are proposed and their performance is investigated under the presence of single and multiple priority classes of traffic. The proposed mechanisms are based on the Distributed Queue Dual Bus network, which has been adopted by the IEEE standardization committee as the 802.6 standard for Metropolitan Area Networks, and address most of its performance limitations. First, the Rotating Slot Generator scheme is introduced which uses the looped bus architecture that has been proposed for the 802.6 network. According to this scheme the responsibility for generating slots moves periodically from station to station around the loop. In this way, the positions of the stations relative to the slot generator change continuously, and therefore, there are no favorable locations on the busses. Then, two variations of a new bandwidth balancing mechanism, the NSW_BWB and ITU_NSW are introduced. Their main advantage is that their operation does not require the wastage of channel slots and for this reason they can converge very fast to the steady state, where the fair bandwidth allocation is achieved. Their performance and their ability to support multiple priority classes of traffic are thoroughly investigated. Analytic estimates for the stations\u27 throughputs and average segment delays are provided. Moreover, a novel, very effective priority mechanism is introduced which can guarantee almost immediate access for high priority traffic, regardless of the presence of lower priority traffic. Its performance is thoroughly investigated and its ability to support real time traffic, such as voice and video, is demonstrated. Finally, the performance under the presence of erasure nodes of the various mechanisms that have been proposed in this dissertation is examined and compared to the corresponding performance of the most prominent existing mechanisms

Second year technical report on-board processing for future satellite communications systems

Advanced baseband and microwave switching techniques for large domestic communications satellites operating in the 30/20 GHz frequency bands are discussed. The nominal baseband processor throughput is one million packets per second (1.6 Gb/s) from one thousand T1 carrier rate customer premises terminals. A frequency reuse factor of sixteen is assumed by using 16 spot antenna beams with the same 100 MHz bandwidth per beam and a modulation with a one b/s per Hz bandwidth efficiency. Eight of the beams are fixed on major metropolitan areas and eight are scanning beams which periodically cover the remainder of the U.S. under dynamic control. User signals are regenerated (demodulated/remodulated) and message packages are reformatted on board. Frequency division multiple access and time division multiplex are employed on the uplinks and downlinks, respectively, for terminals within the coverage area and dwell interval of a scanning beam. Link establishment and packet routing protocols are defined. Also described is a detailed design of a separate 100 x 100 microwave switch capable of handling nonregenerated signals occupying the remaining 2.4 GHz bandwidth with 60 dB of isolation, at an estimated weight and power consumption of approximately 400 kg and 100 W, respectively

Application of advanced on-board processing concepts to future satellite communications systems

An initial definition of on-board processing requirements for an advanced satellite communications system to service domestic markets in the 1990's is presented. An exemplar system architecture with both RF on-board switching and demodulation/remodulation baseband processing was used to identify important issues related to system implementation, cost, and technology development

CarRing IV- Real-time Computer Network

Ob in der Automobil-, Avionik- oder Automatisierungstechnik, die Fortschritte in der Echtzeitkommunikation richten sich auf weitere Verbesserungen bereits existierender Lösungen. Im Kfz-Bereich führen die steigenden Zahlen computerbasierter Systeme, Anwendungen und Anschlüsse sowie die Verwendung mehrerer proprietärer Kommunikationsstandards zu einem immer komplexeren Kabelbaum. Ursächlich hierfür sind inkompatible Standards, wodurch nicht nur die Kosten, sondern auch das Gewicht und damit der Kraftstoffverbrauch negativ beeinflusst werden. Im ersten Teil der Dissertation wird das Echtzeitprotokoll von CarRing IV (CRIV) vorgestellt. Es bietet isochrone und harte Echtzeitgarantien, ohne dass eine netzwerkweite Synchronisation erforderlich ist. Mit bis zu 16 Knoten pro Ring kann ein CR-IV-Netz aus bis zu 256 Ringen bestehen, die durch Router miteinander verbunden sind. CR-IV verwendet ein reduziertes OSI-Modell (Schichten 1-3, 7), das für seine Anwendungsbereiche sowohl typisch als auch vorteilhaft ist. Außerdem unterstützt es sowohl ereignis- als auch zeitgesteuerte Kommunikationsparadigmen. Der Transparent-Modus ermöglicht es CR-IV, als Backbone für bestehende Netze zu verwenden, wodurch Inkompatibilitätsprobleme beseitigt werden und der Wechsel zu einer einheitlicheren Netzlösung erleichtert wird. Mit dieser Funktionalität können Nutzergeräte über ein CR-IV-Netz miteinander verbunden werden, ohne dass der Nutzer eingreifen oder etwas ändern muss. Durch Multicast unterstützt CRIV auch die Emulation von Feldbussen. Der zweite Teil der Dissertation stellt den anderen wichtigen Aspekt von CR-IV vor. Alle Schichten des OSI-Modells sind in einem FPGA mit Hardware Description Languages (HDLs) ohne Hard- oder Softprozessoren implementiert. Das Register-Transfer-Level (RTL)-Hardwaredesign von CR-IV wird mit einem neuen Ansatz erstellt, der am besten als tokenbasierter Datenfluss beschrieben werden kann. Der Ansatz ist sowohl vertikal als auch horizontal skalierbar. Er verwendet lose gekoppelte Processing Elements (PEs), die stateless arbeiten, sowie Arbiter/Speicherzuordnungspaare. Durch die granulare Kontrolle und die Aufteilung aller Aspekte einer Lösung eignet sich der Ansatz für die Implementierung anderer Software-Level-Lösungen in Hardware. Viele Testszenarios werden durchgeführt, um die in CR-IV erzielten Ergebnisse zu verdeutlichen und zu überprüfen. Diese Szenarien reichen von direkten Leistungsmessungen bis hin zu verhaltensspezifischen Tests. Zusätzlich wird eine Labor-Demo erstellt, die grundsätzlich auf ein Proof of Concept zielt. Die Demo stellt einen praktischen Test anstelle szenariospezifischer Tests dar. Alle Testszenarien und die Labor-Demo werden mit den Prototyp-Boards des Projekts durchgef¨uhrt, d.h. es sind keine Simulationstests. Die Ergebnisse stellen die realistischen Leistungen von CR-IV mit bis zu 13,61 Gbit/s dar.Whether be it automotive, avionics or automation, advances in their respective real-time communication technology focus on further improving preexisting solutions. For in-vehicle communication, the ever-increasing number of computer-based systems, applications and connections as well as the use of multiple proprietary communication standards results in an increasingly complex wiring harness. This is in-part due to those standards being incompatible with one another. In addition to cost, this also impacts weight, which in turn affects fuel consumption. The work presented in this thesis is in-part theoretical and in-part applied. The former is represented by a new protocol, while the latter corresponds to the protocol’s hardware implementation. In the first part of the thesis, the real-time communication protocol of CarRing IV (CR-IV) is presented. It provides isochronous and hard real-time guarantees without requiring network-wide clock synchronization. With up to 16 nodes per ring, a CR-IV network can consist of as many as 256 rings interconnected by routers. CR-IV uses a reduced OSI model (layers 1-3, 7), which is both typical of and preferable for its application areas. Moreover, it supports both event- and time-triggered communication paradigms. The transparent mode feature allows CR-IV to act as a backbone for existing networks, thereby addressing incompatibility concerns and easing the transition into a more unified network solution. Using this feature, user devices can communicate with one another via a CR-IV network without requiring user interference, or any user device or application changes. Combined with the protocol’s reliable multicast, the feature extends CR-IV’s capabilities to include field bus emulation. The second part of the thesis presents the other important aspect of CR-IV. All of its OSI model layers are implemented in a FPGA using Hardware Description Languages (HDLs) without relying-on or including any hard or soft processors. CR-IV’s Register-Transfer Level (RTL) hardware design is created using a new approach that can best be described as token-based data-flow. The approach is both vertically and horizontally scalable. It uses stateless and loosely coupled Processing Elements (PEs) as well as arbiter/memory allocation pairs. By having granular control and compartmentalizing every aspect of a solution, the approach lends itself to being used for implementing other software-level solutions in hardware. Many test scenarios are conducted to both highlight and examine the results achieved in CR-IV. Those scenarios range from direct performance measurements to behavior-specific tests. Moreover, a lab-demo is created that essentially amounts to a proof of concept. The demo represents a practical test as opposed to a scenariospecific one. Whether be it test scenarios or the lab-demo, all are carried-out using the project’s prototype boards, i.e. no simulation tests. The results obtained represent CR-IV’s real-world realistic outcomes with up to 13.61 Gbps

A Novel Approach to Pci Simulation Using ScriptSim

In recent years, the Peripheral Component Interconnect (PCI) has become one of the most widely used bus architectures in modern computers. Simulation of the PCI bus, however, has been limited in both research and development. Current commercial PCI simulation software is designed towards compliance and verification testing rather than accurately mimicking PCI bus systems. In addition, most PCI simulation software is inflexible and offers no graphical user interface, instead relying on text files for configuration. This paper presents a novel approach to PCI simulation using ScriptSim, an open-source PCI simulation tool that supports all the features offered by the PCI Local Specification Version 2.2. In addition to extending ScriptSim to include PCI-X functionality and a web-based graphical interface, we introduce techniques that allow us to accurately simulate real-world systems

FPGA Based Embedded Multiprocessor Architecture

Multiprocessor is a typical subject within the Computer architecture field of scope. A new methodology based on practical sessions with real devices and design is proposed. Embedded multiprocessor design presents challenges and opportunities that stem from task coarse granularity and the large number of inputs and outputs for each task. We have therefore designed a new architecture called embedded concurrent computing (ECC), which is implementing on FPGA chip using VHDL. The design methodology is expected to allow scalable embedded multiprocessors for system expansion. In recent decades, two forces have driven the increase of the processor performance: Advances in very large-scale integration (VLSI) technology and Micro architectural enhancements. Therefore, we aim to design the full architecture of an embedded processor for realistic to perform arithmetic, logical, shifting and branching operations. We will be synthesize and evaluated the embedded system based on Xilinx environment. Processor performance is going to be improving through clock speed increases and the clock speed increases and the exploitation of instruction- level parallelism. We will be designing embedded multiprocessor based on Xilinx environment or Modelsim environment

Future benefits and applications of intelligent on-board processing to VSAT services

The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified

Fiber optic networks: fairness, access controls and prototyping

Fiber optic technologies enabling high-speed, high-capacity digital information transport have only been around for about 3 decades but in their short life have completely revolutionized global communications. To keep pace with the growing demand for digital communications and entertainment, fiber optic networks and technologies continue to grow and mature. As new applications in telecommunications, computer networking and entertainment emerge, reliability, scalability, and high Quality of Service (QoS) requirements are increasing the complexity of optical transport networks.;This dissertation is devoted to providing a discussion of existing and emerging technologies in modern optical communications networks. To this end, we first outline traditional telecommunication and data networks that enable high speed, long distance information transport. We examine various network architectures including mesh, ring and bus topologies of modern Local, Metropolitan and Wide area networks. We present some of the most successful technologies used in todays communications networks, outline their shortcomings and introduce promising new technologies to meet the demands of future transport networks.;The capacity of a single wavelength optical signal is 10 Gbps today and is likely to increase to over 100 Gbps as demonstrated in laboratory settings. In addition, Wavelength Division Multiplexing (WDM) techniques, able to support over 160 wavelengths on a single optical fiber, have effectively increased the capacity of a single optical fiber to well over 1 Tbps. However, user requirements are often of a sub-wavelength order. This mis-match between individual user requirements and single wavelength offerings necessitates bandwidth sharing mechanisms to efficiently multiplex multiple low rate streams on to high rate wavelength channels, called traffic grooming.;This dissertation examines traffic grooming in the context of circuit, packet, burst and trail switching paradigms. Of primary interest are the Media Access Control (MAC) protocols used to provide QoS and fairness in optical networks. We present a comprehensive discussion of the most recognized fairness models and MACs for ring and bus networks which lay the groundwork for the development of the Robust, Dynamic and Fair Network (RDFN) protocol for ring networks. The RDFN protocol is a novel solution to fairly share ring bandwidth for bursty asynchronous data traffic while providing bandwidth and delay guarantees for synchronous voice traffic.;We explain the light-trail (LT) architecture and technology introduced in [37] as a solution to providing high network resource utilization, seamless scalability and network transparency for metropolitan area networks. The goal of light-trails is to eliminate Optical Electronic Optical (O-E-O) conversion, minimize active switching, maximize wavelength utilization, and offer protocol and bit-rate transparency to address the growing demands placed on WDM networks. Light-trail technology is a physical layer architecture that combines commercially available optical components to allow multiple nodes along a lightpath to participate in time multiplexed communication without the need for burst or packet level switch reconfiguration. We present three medium access control protocols for light-trails that provide collision protection but do not consider fair network access. As an improvement to these light-trail MAC protocols we introduce the Token LT and light-trail Fair Access (LT-FA) MAC protocols and evaluate their performance. We illustrate how fairness is achieved and access delay guarantees are made to satisfy the bandwidth budget fairness model. The goal of light-trails and our access control solution is to combine commercially available components with emerging network technologies to provide a transparent, reliable and highly scalable communication network.;The second area of discussion in this dissertation deals with the rapid prototyping platform. We discuss how the reconfigurable rapid prototyping platform (RRPP) is being utilized to bridge the gap between academic research, education and industry. We provide details of the Real-time Radon transform and the Griffin parallel computing platform implemented using the RRPP. We discuss how the RRPP provides additional visibility to academic research initiatives and facilitates understanding of system level designs. As a proof of concept, we introduce the light-trail testbed developed at the High Speed Systems Engineering lab. We discuss how a light-trail test bed has been developed using the RRPP to provide additional insight on the real-world limitations of light-trail technology. We provide details on its operation and discuss the steps required to and decisions made to realize test-bed operation. Two applications are presented to illustrate the use of the LT-FA MAC in the test-bed and demonstrate streaming media over light-trails.;As a whole, this dissertation aims to provide a comprehensive discussion of current and future technologies and trends for optical communication networks. In addition, we provide media access control solutions for ring and bus networks to address fair resource sharing and access delay guarantees. The light-trail testbed demonstrates proof of concept and outlines system level design challenges for future optical networks

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression