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Other Resources
Preparing your Network for Synchronous Ethernet
Application Brief
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As service providers continue to transition applications – including voice, video and data – to packet-based next-generation networks, they're in search of a cost-effective technology to support their needs for timing and synchronization. Without such a technology, these applications will fail completely, or at best suffer packet loss, dropped frames, degradation and a Quality of Experience that doesn't live up to consumer
expectations.
One technology that has emerged to enable operators to migrate to packet networking while retaining backward compatibility is Synchronous Ethernet (or Sync-E). It’s simply an evolution from packet over SONET/SDH to Ethernet that retains the physical layer synchronization and addresses new and old service provider requirements. Sync-E enables faster speeds, greater efficiency and next generation services, all while minimizing capital investment.
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Deploying Reliable DOCSIS Synchronization
Application Brief
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This document provides a guide for cable operators to deploy the DOCSIS Timing Interface in their networks.
It is critical to maintain good synchronization in a DOCSIS network. Cable modems (CMs) use synchronization to determine when to transmit. Without good synchronization CMs will transmit at the wrong time, causing complete loss of transmission of not only the errant CM, but also the CMs it transmits over. M-CMTS specifications include the DOCSIS Timing Interface (DTI) to ensure highly accurate and reliable synchronization of the entire DOCSIS network. For an overview of the DOCSIS Timing Interface and Synchronization please refer to the list of documents at the end of this white paper.
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What Time is it?
The Importance of Time in the Network
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IP Networks are now the primary communication medium for most Enterprise application needs including voice, wireless, data and video communications with the goal of being able to reduce the cost and number of different networks and systems, while at the same time, allowing applications and services increased access to data that can be quickly shared between each other. These applications, performance metrics, and a number of management and security mechanisms, all require increasingly accurate Time of Day system clock synchronization... so accurate that distributing time over the IP network has become a challenge.
This paper examines some of the challenges in using Network Time Protocol (NTP) to provide accurate time of day synchronization for IP networks and systems, and what else you may be able to do to help address the problem.
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Five Essential Elements of Carrier Class NTP
Telecom operators must bring to managed IP the same high levels of quality assurance consumers expect in the circuit switched environment.
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Never before have telcos, cable operators, equipment makers, and content providers had so many ways to engage the consumer – creating a cacophony of complex provider, service, content, and device scenarios. Operators find themselves caught in a convergence of multiple new-media technology plays. Consumers meanwhile struggle to make brand choices as they switch from “watching what’s on,” i.e., linear consumption models, to more on-demand models like IPTV, online social networking, games, and downloads.
Telcos, however, have historically enjoyed a unique advantage versus the other players: superb quality assurance. For decades people have expected to hear a dial tone when they pick up the phone. Clearly, a winning strategy will be to bring that same level of customer confidence to other arenas as well.
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How NTP Impacts the New Telecom
NGN Series Whitepaper
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No longer confined to the data center, Network Time Protocol is an emerging force in the delivery of new digital services and the reliable operation of telecom networks.
In the last few years, telecom networks have undergone a substantial change — both in terms of technology as well as in the services they support. In particular, packetbased technologies have placed new demands on network-wide timing. This paper will discuss how these changes are creating new requirements in the accuracy, security, and availability of NTP-based time. Network operators will have to adjust.
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Timing and Synchronization in WiMAX Networks
NGN Series Application Brief
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The emerging Worldwide Interoperability for Microwave Access (WiMAX) standard promises to be the core enabling technology for next-generation broadband mobile wireless applications including last mile broadband, hotspots, cellular backhaul and full mobile high speed broadband access. Architected to ensure low latency and low jitter to support real-time services, WiMAX provides a wide range of QoS levels appropriate for a variety of applications and subscriber requirements including internet access, streaming services, interactive gaming, video-on-demand, and voice-over-IP (VoIP) services. With its basis in robust Orthogonal Frequency Division Multiplexing (OFDM) modulation, shared data rates up to 70 Mbps, and an outstanding range of 3 to 5 miles, WiMAX leverages an internet protocol (IP) core that creates an open architecture for mobile data networks while significantly reducing network cost and complexity for delivery of high bandwidth personal broadband services.
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Telecom Solutions Strategy
Presented by Gurdip Jande, Symmetricom
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Covers Networks and Role of Timing, Emerging Timing Distribution Technologies and Product Portfolio and Evolution.
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Timing Technologies Updates
Presented by Jim Olsen, Symmetricom
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Covers Synchronization and Timing in Next Generation Networks.
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Deploying Reliable and Economic DOCSIS 3.0 Modular Architectures
Presented by Jim Olsen, Symmetricom
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Covers the M-CMTS & DOCSIS Markets, and how Synchronization plays a role.
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Quality of Experience for Next-Generation Services
Presented by Joe Neil, Symmetricom
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Covers introduction to Integrated Triple Play Solutions and QoE Assurance Solutions.
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Synchronous Ethernet for Carrier-Ethernet Networks
Presented by Michel Ouellette, Nortel
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Examines Layer 1 Synchronous Ethernet solutions from Nortel.
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Synchronous Ethernet and Layer 2 Synchronization
Presented by Michel Ouellette, Nortel
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Investigates Layer 2 Timing Distribution using Ethernet Provider Backbone Transport (PBT)
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Symmetricom Product Line Update
Presented by Kevin Hsu, Symmetricom
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Provides a roadmap update of Symmetricom's key product lines.
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Time of Day Requirements for Network Security
Presented by Alourdes Sully, Hydro One Networks
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Session notes from SynCan2007, presented April 25-26 in Montreal.
Examines network security requirements, and the critical role of Time of Day in Network Security.
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Telus Synchronization Network Evolution
NGN Series Customer Case Study
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Telecom networks and technologies continue to evolve at a blistering pace to support the introduction of new IP based services such as IPTV. Telcos continue to invest in new technologies and equipment that is needed to support the delivery of new services. This paper focuses on a specific initiative by one of Canada’s leading service providers, TELUS, that is aggressively attacking the challenge of constructing a next generation network. TELUS continues to invest in the deployment of leading edge technologies and has announced their intentions to upgrade the synchronization and timing infrastructure as part of the overall strategy.
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Sync Requirements for High-Performance Cable Networks
Synchronization: Critical to Network Operation
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Synchronization of time and frequency has always been crucial to cable networks since the development of data over cable service interface specification (DOCSIS®), the first and still current cable-modem interface standard. Synchronization remains essential to cable networks for two reasons: first, because the physical-transmission medium, in this case coaxial cable, is shared by all cable modems on the network, basic connectivity is likely to cause high levels of transmission interference unless synchronization is precise. In fact, existing DOCSIS systems maintain five-nanosecond time-andfrequency accuracy within a given cable modem termination system (CMTS). Second, various new specifications for flexible CMTS architectures and new services like T1 or E1 circuit emulation require good synchronization in cable networks.
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Timing and Synchronization in Next-Generation Networks
NGN Series SyncTime Overview
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In traditional circuit switched or Time Division Multiplex (TDM) networks, frequency synchronization is required for alignment of transport equipment. In the each node of the network, synchronization is distributed from a synchronization system to all the network elements, and through out the network from node to node with TDM frame alignment of PDH or SONET/SDH. In addition to synchronization of transport and switching equipment, synchronization is also needed by service endpoints such as PBXs (Private Branch Exchanges) and IADs (integrated Access Devices). These endpoints require a service clock to ensure the alignment of the originating and terminating service endpoints for proper service operation.
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Timing and Synchronization in Next-Generation Networks
Services and Applications Perspective Brief
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Time and frequency alignment is critical for ensuring quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium. As telecom networks evolve from Circuit to Packet switching, proper synchronization (frequency and time) is needed for IP networks to achieve performance quality comparable to that of legacy circuit-switched networks.
Accurate time alignment (time-transfer or time-of-day) is needed to support QoS and traffic engineering, whereas frequency alignment (network synchronization) is required to minimize slips. In the event of slips, i.e., buffer overflow/underflow events, two options are available. One, appropriate for non-real-time applications, is to retransmit the packets/frames, which is equivalent to the reduction of bandwidth
utilization efficiency.The other, applicable to real-time applications, where retransmission may not be an option, is to accept the loss and attendant degradation of service quality.
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Timing and Synchronization in Next-Generation Wireless Networks
NGN Series Application Brief
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Mobile operators are racing to deploy high-speed data services in order to acquire and retain lucrative mobile professional users. Because high-speed data services require increased backhaul capacity, mobile operators are seeking alternative, lower-cost backhaul methods in order to meet increasing data demands. At the same time, costreduction measures must not sacrifice consistent and high-quality service. As the network shifts to an Ethernet/IP backhaul, maintaining precise frequency distribution throughout the network is essential for maintaining service level assurance. The quality of synchronization mobile operators put into their network directly impacts the quality of service (QoS) that comes out of their network.
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IEEE 1588 Precision Time Protocol
Frequency Synchronization Over Packet Networks
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Telecommunications networks are rapidly shifting from circuit switched to packet switched technologies to meet exploding demand for bandwidth in both core and access networks. Traditional circuit switched TDM networks were engineered to carry precise frequency synchronization throughout the network. Access platforms such as wireless base stations and MSANs (multi service access nodes) rely on synchronization delivered over the network backhaul connection to assure high QoS for end user applications. A key dependency in the evolution to Ethernet backhaul in telecom networks is the ability to deliver carrier grade synchronization over Ethernet to remote wireless base stations and access platforms.
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IP Telephony Clock Synchronization: Best Practices
A Whitepaper by Cisco and Symmetricom
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Cisco Systems' whitepaper Cisco IP Telephony Clock Synchronization: Best Practices states that accurate time is essential for router and server log file accuracy, as well as robust network management systems. For Cisco customers deploying IP telephony, the best practice is to have two dedicated NTP timing appliances for each call manager cluster, to ensure good performance, improved troubleshooting, and accurate call detail records (CDRs) for billing.
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Symmetricom Telecom Solutions Strategy
Presented by Gurdip Jande, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers key drivers for Timing and Synchronization, and evolution of Symmetricom's key platforms to support these needs.
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Timing and Synchronization in Next-Generation Networks
Presented by Jim Olsen, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers key concepts and requirements for Timing and Synchronization, for a range of networks and services, including Circuit Emulation Services, Wireless Networks, Video Services, IP Performance Monitoring, Passive Optical Networks (PONs), and Business-class Voice over IP (VoIP).
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Emerging Timing Technologies
Presented by Jim Olsen, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers evolution of Timing and Synchronization standards, protocols and technologies, including Universal Timing Interface (UTI), Precise Time Protocol (aka IEEE 1588), Network Time Protocol and recent enhancements, and an update from the ATIS IPTV Interoperability Forum.
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Timing at the Network Edge
Presented by Jim Olsen, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers evolving issues in Edge, or Access, Networks, and distributing Timing and Synchronization to the edge of packet-based networks, and evolving solutions to this growing requirement.
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Case Studies in Timing and Synchronization
Presented by Jim Olsen, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers a number of case studies from the field, involving legacy equipment, Primary Reference Sources, asymmetric routing delay, SLAs, and proving timing and synchronization for Next Generation Networks.
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Symmetricom Product Line Update
Presented by Kevin Hsu, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers key evolutions for Symmetricom's key platforms and products, including TimeHub 5500, TimeProvider, SSU-2000, TimeCesium, TimeSource, TimeGPS, TimeCraft and TimePictra. Discusses enhancements in stability, holdover, and scalability, new technologies like PackeTime, hardware assisted time-stamps, and module enhancements for PRS, outputs, that deliver greater performance, accuracy, redundancy, reliability, management and security.
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Challenges in Support IPTV
Presented by Phil McKinnon, Empowered Networks
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Provides a technology primer for Digital Video and IPTV technologies, and key issues affecting IPTV Quality of Experience, and testing strategies to ensure success.
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DOCSIS 3.0 & Two-way Time Transfer
Presented by Jeremy Bennington, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Provides an overview of Cable Networks and technology, how synchronization plays a role, key standards (DOCSIS 3.0 and M-CTMS), and profiles Symmetricom's TimeCreator 1000 solution, with integral support for Distributed Timing Interface (DTI). Also discusses Universal Timing Interface (UTI), that supports both DTI, and Telecom Timing Inteface (TTI).
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Symmetricom Global Operations and Services Update
Presented by Larry Fowler, Symmetricom
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Session notes from SynCan2006, presented June 13-14th in Toronto.
Covers Symmetricom's factory facilities, and quality programs, how they are impacting Delivery and Quality, continuous improvement programs, and enhancements to quality, services and repairs, and support for customer modernization of their networks.
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Passive Optical Networks
Unlocking the Bandwidth Potential of Fiber with Precise Sync
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The need for telcos to deliver the Triple Play of voice, video and data in order to compete with services offered by cable companies has reignited focus on broadband optical access systems based on Passive Optical Networking (PON). While the economic downturn stalled implementations of new technologies as the communications industry focused on maximizing revenue from existing infrastructure (such as DLS over copper wires), the Triple Play has returned PON to the frontline of emerging technologies. PON components are key to unlocking the bandwidth potential of fiber.
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ADSL Synchronization
Enhancing Network Performance with Precise Timing
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In every digital communications network, precise synchronization and timing is required for the reliable transmission of voice, video and data. Synchronization paces the flow of information and ensures the network performs at peak efficiency, which is critical for delivering real time services with the end user's quality of experience in mind.
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Enhancing Network Performance in UMTS Networks
Synchronizing Node B Base Stations Will Improve QoS
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Advanced mobile operators are racing to deploy third generation (3G) high-speed data service offerings in order to acquire and retain lucrative mobile professional users. Mobile professionals are the most profitable customers and the most discriminating - they are the least to tolerate poor quality of service (QoS).
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Enabling Real Time Services in IP/MPLS Networks
Precise Synchronization Key for Achieving Performance Level of Circuit Switched Networks
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While Multi-Protocol-Label-Switching (MPLS) is a promising methodology for enabling packet-switched (IP) networks to provide real-time services, precise timing and synchronization is essential in order to achieve the same performance quality as traditional circuit-switched networks. Minimizing time-delay variation (TDV) clearly improves network performance. Given that the conventional approach to keeping TDV within bounds is to overprovision the network, that is, provide excess bandwidth capacity, any method that reduces TDV increases the efficiency of bandwidth utilization.
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Synchronization in 3G Networks
Based on the Universal Mobile Telecommunication System (UMTS)
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The demand for a greater variety of mobile and fixed wireless services has led to the introduction of third generation (3G) systems. Today, several 3G networks based on UMTS have been deployed and new networks are being launched globally. According to the UMTS Forum, 3G networks will represent a total operator-retained annual revenue of more than $300 billion by 2010. 3G networks provide traditional (2G) services such as voice and SMS but they also allow the introduction of many more services to users worldwide. In effect, 3G/UMTS unifies telephony, mobility, internet and computer technology.
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Synchronizing Telecommunications Networks
Synchronizing SDH/SONET
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Synchronous Digital Hierarchy (SDH) and Synchronous Digital Network (SONET) are new transmission systems that provide for standardized highspeed optical transport. The goal of SDH and SONET is to provide ease of networking, intervendor compatibility, standardized interfaces, and standardized overhead for operations, administration, maintenance, and provisioning.
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Synchronizing Telecommunications Networks
Fundamentals of Synchronization Planning
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In recent years, the importance of synchronization has increased due to the extensive digitization of telecommunications networks and to the introduction of SDH and SONET technologies. These events have placed more demands on synchronization planning, performance, and operation.
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Synchronization Planning Guidelines
An Introduction to Network Synchronization
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Telecommunications networks, like most large systems, operate at peak performance when all components are working together at the same rate and at the proper time.
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Synchronizing Telecommunications Networks
Basic Concepts
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With the rapid deployment of digital switching systems and transmission facilities and the introduction of SDH and SONET, the importance of synchronization in telecommunications has dramatically increased.
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Synchronization for Improving VoIP Quality
A Whitepaper by Symmetricom
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The following paper examines influences that contribute to the Quality of Service (QoS) issues surrounding Voice over Internet Protocol (VoIP) and the deployment of Next Generation Networks (NGNs). The migration from circuit-switching to packet-switching technologies has several advantages in both cost and architectural aspects that make VoIP attractive to operators. However, questions remain as to whether the voice quality can meet the current high standards that users have been accustomed to in the past.
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Low-Cost Yet Reliable GPS-Based PRS
Using the Low-Cost Global Positioning System as a Reliable Primary Reference Source
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Accurate frequency is always generated by an atomic clock. In fact, the international standard definition of time and frequency is based on the Cesium atom, and accurate frequency is typically generated by a Cesium Beam Standard. However, due to the relatively higher cost of both purchasing and maintaining a Cesium standard, it is often preferable to obtain precise frequency via a radio transfer standard such as the Global Positioning System (GPS).
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Clock Accuracy: Free Run or Holdover?
Ed M. Underwood, Senior Staff Engineer, Datum
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Clocks are devices used to provide timing and synchronization information to the equipment elements of a digital transmission system or network. Clocks are embedded within switching or transport equipment or in stand-alone synchronization equipment such as Timing Signal Generators (TSGs) and Primary Reference Sources (PRSs). They are generally interconnected in a hierarchical fashion by the digital facilities of the synchronization network. The interconnection of the clocks assures that normally (no facility failures) all the clocks are synchronized such that they are all operating at the same average frequency.
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GPS Without Selective Availability
By R. Fuller, E. Fudurich, F.E. Weiler
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Explore what the removal of Selective Availability, the intentional degredation of GPS signals for civilain users, means to those in time transfer and network synchronization applications.
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Sync Status Messages to Support Advanced Self-Healing Telecom Networks
The use of Synchronization Status Messages (SSMs)
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SSMs are designed to allow synchronization reference selection strategies compatible with network topologies such as point-to-point, linear, mesh, ring or others, with the Network Elements (NEs) in line, loop, through, or externally timed modes of operation.
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Synchronization Services
Ken Bourne Takes you through Synchronization basics
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From synchronization network design and engineering to Audits, project management, and installation. Empowered Networks has synchronization from start to finish.
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Managing Time Machines
Synchronization for Network Elements
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Historically, synchronization and timing equipment have been left unmanaged in the network. Primary Reference Sources (PRSs), Synchronization Supply Units (SSUs) or other synchronization equipment have been installed in central offices and exchanges and verified for proper operations through local "craft" terminal software.
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