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Dedicated To Our Parents And Family Members
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Preface
Broadband data services are the next step in the evolution of telecommunications. Realizing that this is the next major utility, plans should be made to create a financially viable and reliable broadband network. Through the years, water and electric services have been provided by a public utility. The next utility services provided have been garbage, sewage, and telecommunications. While not exactly a utility, public transportation and highway systems could also be viewed in this category. Broadband data services are an extension of existing telecommunications and are the next evolutionary step in today¶s society and marketplace. When businesses and people are looking for places to locate, they expect most basic utility services to be available (water, electric, sewage, garbage, phones, etc.). Therefore, a primary focus becomes ³Is broadband data service available?´ It is this factor that often determines whether or not these individuals locate in a specific area.
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Acknowledgements
The project not only benefits the entire community but also myself as I am also a customer of the cable system. Special thanks go to our family for their support throughout my pursuit of this degree. I also want to thank my co-workers at the NESCOM/ NDC for their help and support in this project. Our Teacher helps out when we were strongly griped about the project. Engr. Muhammad Tahir, Head of Telecomm Department and Mr. Waheed Akhtar, Head of Optical Fiber System department always help us out when we were buried with some Technical issues which was not understandable to us and the cable guys in the field for going out and conducting all the leg work. I would also like to thank Mr.Imran Mir, General Manager (Telecom Infrastructure & Maintenance) for pushing us to finish this thesis and meet my deadlines on time.
AZHAR HASSAN Reg. No: SUIT±04±01±77008 Roll No. 04±FA/01659 E-Mail:
[email protected]
Date:
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STATEMENT OF SUBMISSION
This is to certify that AZHAR HASSAN, Roll No 04/FA-01659, Reg. No: SUIT±04±01± 77008 and AKRAM UL HAQ Roll No. 04±FA/01655, Reg. No: SUIT±04±01±77004 has successfully completed the final project named as: DATA ACQUISITION SYSTEM, at Sarhad University of Science and Information Technology, Peshawar, to fulfill the partial requirement of the degree of B.Tech Honors (Electronics and Telecom).
___________________________ External Supervisor Name of External Supervisor Designation Organization Name
________________________ Internal Supervisor SUIT, Peshawar
___________________________ External Examiner Name of External Examiner Designation Organization Name
________________________ Dean, Faculty of __________ SUIT, Peshawar
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Abstract
Islamabad/ Rawalpindi are large urban community located in North of Pakistan. Like most large communities, the city is generally responsible for meeting the needs of its occupants. In the case of Islamabad/ Rawalpindi, a need most residents wanted addressed was the ability to use broadband data/Internet services. In order to meet this need, Different Telecom companies began working on a project which would deliver broadband services to all of its residences. Telecom Companies began the project as an upgrade to the existing coaxial cable plant and continually revised the plans, goals, and objectives until the decision was made to design, construct, and manage a complete fiber network. This Fiber-to-the-Home network combined the goals of the community, the cable system, and the City of Islamabad/ Rawalpindi. This new network would help future-proof the system, and it would also allow critical facilities to be networked and monitored for security and ease of communications. From its conception, once sufficient funding had been secured, the proposal for the design-build of the system was created. Throughout the construction phase of the project, many design changes were made to improve services and cut costs. In the end, Islamabad/ Rawalpindi had constructed a self- contained network capable of providing voice, data, and video services to its residences. This network is able to be managed by computers and a small group of installation and field personnel.
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Table of Contents
Chapters Detail Abstract Preface Acknowledgements 1.0 1.1 1.2 2.0 2.1 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.3 3.0 3.1 3.1.1 3.1.2 3.2 4.0 4.0.1 4.0.2 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.3 4.3.1 4.3.2 5.1 5.2 5.3 5.4 5.4.1 Introduction Statement of problem A community network Establishing the need for a community network Roles of Government Developing a technology plan The Plan Itself Published Plan Budget Process for Determining Needs (Needs Analysis) Beginning Plan Cost Benefit Analysis Hints for Writing the Proposal Project Completion Considerations Technologies for Broadband Networks Wired Solutions Copper/Coaxial Cabling Fiber Optic Cable Determining The Best Method Designing the Network and Overall Plan Network Plans Network Applications Determining the Area to be served Determining Network Services to be offered IP Video Gaming Voice Services General Internet Use 4.2.5 Social Trends Determining and Designing Applications for Specific Areas Voice and Video Complexities Fiber as the Network of Choice Determining how the project will be managed Determining How the Progress & Status Will Be Updated & Reported Setting a Schedule and Maintaining Project Deadlines Examining Bills of Materials (BOMs) and Establishing Actual Equipment Consideration 04 Page #
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6.0 7.0 8.0 9.1 9.2 9.3 9.4 10 10.0 10.1 10.2 10.3 10.3.1 11.0 12.0 12.1 12.2 13.0 14.0 14.1 14.1.1 14.1.2 14.1.3 14.1.4 14.1.5 14.2 14.2.1 15.0 16.0 16.0.1 16.0.2 16.1 16.1.1 16.1.2 16.1.3 16.1.4 16.1.5
Informing the Public and Marketing Represented In Every Layer of the FTTH Value Chain Why FTTH? Fiber versus Copper How do Optical Fibers Work? Types of Lasers Used Single and Duel Fiber Systems Selecting and Evaluating Technologies to Meet Network Plans Basic PON Understanding Examining B-PON Architecture Examining E-PON Architecture Examining G-PON Architecture B-PON And G-PON Differences Architecture PON Network Telephony Considerations Conventional Switched Circuit Telephone Example VOIP System Video IP TV-TV Transmitted Over Internet Protocol Waves of Transmitting Video Waves of Transmitting Video-Wave Division Muxing Waves of Transmitting Video-Broadcast Headend Waves of Transmitting Video-Broadcast Subscriber Waves of Transmitting Video-IP Headend Waves of Transmitting Video-IPTV Subscriber Waves of Transmitting Video-IPTV Uni-cast Waves of Transmitting Video-IPTV Multicast PON Link Budgets Headend Overview of Headend Block Diagram Of Headend Over View Of Headend Equipment Coaxial Cable Dish Antennas LNB Satellite Receivers Modulators
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16.2.0 Optical Headend 17.0 17.1 17.1.1 17.1.2 17.1.3 17.2 Completion of the Project Beta-Testing Network and Physical Testing Service testing Choosing Beta-Test Individuals 9.2 Performance Testing Regular Tests and Preventative Maintenance 75
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Introduction
Community projects are often difficult because of lack of support and funding. In the end, these projects can be very beneficial for the people they serve. They typically address a critical need and provide a service previously unavailable. Public projects generate a wide range of conflicting opinions and ideas. These controversial issues arise because of a multitude of needs. To develop a consensus, it is critical that the public be informed of project details. This is often difficult in rural areas where rapid communication is not readily available. Information technologies can serve and address this problem. With the expansion of fast wired and wireless networks in recent years, information technologies have experienced great advances. Such networks can greatly facilitate communication among potential community project beneficiaries and stakeholders. Thus, a community information network is both a solution for facilitating communication and also a community project in its own right. It was for this reason that the current project of bringing a fast wired and wireless network to the City was proposed. In larger communities, private companies usually recognize the need and have the extra incentive of profit. In small communities and regions, although need is recognized ,it is often not addressed because low population density makes the project cost-prohibitive. Private companies require a 3-5 year ROI (Return on Investment) for a project to be considered profitable, an unlikely goal in rural areas. Accordingly, a public project may be created and implemented.
1.1
Statement of the Problem
Recent years have led to an increasing trend in use of and dependence on high speed broadband networks. The problem with this trend is that often times, small cities and communities get left behind because of lack of funding and an overall lack of knowledge about how to correct this problem. Therefore it is necessary for community leaders to gain the necessary knowledge and take the needed steps to address the needs of the citizens and correct this problem. This thesis will provide the process for design of a Fiber-to-the-Home (FTTH) system for Lahore, Karachi, Islamabad. The Islamabad/ Rawalpindi system will then be used as an example design for other cities and communities to follow.
1.2
A Community Network
During the build process, certain design steps and considerations must be followed. Each chapter in this paper is designed to point out these procedures, as well as provide a starting point.
2.0 Establishing the need for a community network
A critical piece of infrastructure for any community or nation is the communications network. In today¶s society, communications plays a key role in all aspects of business and everyday life. The general public spends a good deal of time either being entertained by communications technology or using it to communicate with others. The cell phone has become an integral part of everyday life. However, as the demand for
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communications has increased, the technologies in communities have remained virtually unchanged.
This creates the following questions:
y y y
Why is it that rural communities are still receiving TV services via coaxial cable? Why is it that the telephone companies are still using copper lines in these rural areas instead of fiber? Why is it that people living in rural communities having only dial-up Internet service? Why is it that cellular coverage in these rural areas is limited and sometimes nonexistent?´
y
All of these questions have the same answer ± infrastructure cost and return on investment (ROI). Because they know they will never fully recover their investments, large companies do not and will not invest millions/billions of dollars in rural areas with low population density
2.1 Roles of Government
One role of the government, historically speaking, is to provide services for its citizens and equal access and opportunity to its entire population, especially when private companies refuse to make such an investment. Thus, technology and communications can be a major undertaking for rural communities. The government or local community may subsidize the cost of the project and pass that savings along to consumers. The community network will then be open and will be viewed as community-owned. Benefits include lower overall cost of ownership, local control, interaction with the end user, and a meeting of actual needs. Such a network will enable critical community facilities to be linked. The wide-area network (WAN) will be viewed as a large local area network (LAN). First responders, including police, emergency squads, fire, and dispatch will then be located on one central network, sharing not only voice, but also video and computer data. This highly efficient means of communication will help reduce costs and will improve the quality of communications, thereby reducing the risks of mistakes and increasing the quality of life for the citizens of the community. It is vital to have a well informed community, especially in times of crisis. During times of emergencies and natural disasters, if communication and response systems are advanced enough to give an additional two-minute warning, lives will be saved and tragedies will be averted. Emergency service personnel send reports and communications to state and federal officials during these times, and a high-speed network can provide for rapid data transfer. For example, monitoring of rain gauges and river levels is essential to give early warnings to the public in times of heavy rains. By placing the control of the network in the hands of the community, local agencies will have full ability to implement necessary changes when the need arises, and they will not need to pay for use of someone else¶s network or get approval from a corporation. The community-owned and operated network will also allow more services to be provided. Public information will be distributed cheaply, quickly, and effectively.
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2.2 Developing a technology plan
In order to successfully own or operate a community network, a solid technology plan must be developed and implemented by the local authorities. This plan must be based on the goals of the community and must outline the services or applications that will be provided by the network. A technology plan is critical when determining the design of the network and how the project will be implemented. As with most construction and community projects, funding plays a significant role. Generally, a community project of such large scale will be funded and completed in phases. Therefore, the technology plan must allow for expansion and effective delivery of services in the most time-effective and cost-effective way possible. Delays may result if a clear plan is not in place. Furthermore, portions of the network may have to be redesigned if the plan is inadequate.
2.2.1 The Plan Itself
The technology plan serves as a driving mechanism to complete the project and keep the focus on providing technological services to the community. This plan should emphasize the goals of the organization and be integrated into part of the organizations, te n-year goals and objectives. This plan should allow for additions as future technologies are developed and standardized. The technology plan should also include a review and approval process for any new technologies or solutions that may arise. This approval process is necessary to protect the interests of the organization as well as to ensure that money invested in the proposed technology is used with the community¶s best interests in mind.
2.2.2 Published Plan
The technology plan should be a published document which citizens can view and to which they can respond. The plan should include a contingency process for replacing and upgrading current technologies and projects. This plan should include maintenance of existing systems, while also protecting future endeavors. This plan should be approved by management and made available to all employees of the organization.
2.2.3 Budget
As part of the technology plan, budgetary constraints must be addressed, as must depreciation and life-cycle of equipment. The plan should demonstrate awareness of these issues and have mechanisms in place to address them. The plan should also Include a proposed budget and costs for various stages of proposed and existing projects. This plan should exhibit the goals and outcomes of all project parts and can be used as leverage and support when seeking funding. As part of the funding process, it is necessary to have a strong technology plan in place. In some cases, a marketing plan and how revenues will be generated from the system should also be indicated. Often, strict guidelines and a history of having completed other large projects successfully must be provided. The latter is generally demonstrated by showing financial records for other projects and an overall history of meeting goals and completing projects.
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2.2.4 Process for Determining Needs (Needs Analysis)
A solid and effective technology plan starts by determining the needs of the community. Although this is no simple task, it can be accomplished as follows:
Methods to determine Needs
y y y y
Create a survey and questionnaire and allow community members to respond and show their concerns Establish a board of advisers made up of community leaders, key business personnel, and community volunteers Have public forums and informational meetings Listen to feedback from local constituents.
2.2.5 Beginning Plan
After gathering preliminary information, the area to be served can be selected, and the initial plan can be formed. What is important to keep in mind is that the project will most likely be built in small pieces and that the technology selected must be adaptable to future upgrades.
Considerations to include
y y y
The useful life of the chosen product The time it will take to install the project How easily the technology can be upgraded and expanded to meet the objectives of the long-range technology plan.
2.2.6 Cost Benefit Analysis
In addition to a strong technology plan, a marketing survey or needs analysis and a cost benefit analysis should be performed. This is key to success when searching for a grant or loan program to complete the various stages of planned projects. It is best to have these three instruments in place prior to beginning the project and searching for funding. Evidence that the project can be successful and self-sustaining is necessary. Without it, the funding will not be approved, no matter how beneficial the outcome of the project. Depending on the sources of funding, different guidelines must be followed. Information gathered must be presented according to the requirements of the funding agency.
2.2.7 Hints for Writing the Proposal
Granting organizations often require Adherence to strict formatting guidelines Submission of various legal and certification documents
Compliance with a set of basic criteria.
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While most of these aspects are easy to fulfill, success is difficult in the absence of a clear and complete technology plan. Unless the plan is already in place, both documents must be simultaneously created, which can cause unnecessary complications and delays. As part of most large grant applications, public forums or meetings need to occur in order to substantiate the need and support for any proposed project. The technology plan facilitates these public assemblies because the public will be aware of and excited about Current and proposed projects. These public forums fulfill a requirement of the grantor but also serve as a form of checks and balances so that a project¶s worthiness and potential for success can be determined before actually seeking funding.
2.3.4 Project Completion Considerations
The grantor will provide guidelines and a timeline for completion of the project. These are in place to make sure that progress is made and that the project is completed in a reasonable amount of time. In some cases, milestones will be defined and progress will be tracked. Failure to comply with guidelines set by the grantor could result in withdrawal of funds and ineligibility for future funding. It is also necessary when planning the project to have a contingency fund (should unexpected costs arise) and sources of matching funds. In some cases, local match can be ³in-kind,´ using existing employees and equipment provided by the grantee, or the grantor may require cash for the remaining capital necessary to complete the project. Regardless of which method is used, the grantor will want documentation and proof that the grantee is able to meet these requirements and that the project will be realized. Upon completion of the project, the grantor will often want clearly demonstrated outcomes of the project and a quantitative analysis of the project. Generally, as part of the grant application, it is necessary to provide information as to how the project can and will be evaluated. Upon completion, these metrics will be evaluated and stated in a final report to the granting agency. Although granting agencies want quantitative results, they often will ask for qualitative results as well. These can be a little more difficult to demonstrate. Qualitative results must be measured objectively and can be shown by overall improvement in the way of life.
3.0 Technologies for Broadband Networks
When considering a large communications network, it is often necessary to analyze the potential deployment options and the technologies behind them. The method of delivery is a critical factor, depending on the services deployed. The delivery methods can be broken down into two basic forms, wired technologies and wireless technologies. Each method has its strengths and weaknesses. It is careful evaluation of these strengths and weaknesses that determines which method suits the needs for a particular network. Reliability, dependability, and support are prime factors in determining which method to use. These require that the network use a well-accepted and tested architecture. Experimental implementations and new hardware/technology are generally not considered because they do not have established reliability, dependability, and support. The last consideration is the adaptability of the method for use with future technical advances.
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3.1 Wired Solutions
There are many wired solutions available and in use today. Traditional cable systems use coaxial cable, while telephone companies use twisted pairs of wire. Newer telephone systems use fiber optic cable. There are several instances in which cable companies are now integrating fiber into their existing plant or completely rebuilding their plants with fiber. Several companies that have rebuilt over the past decade have elected to use HFC (Hybrid Fiber Coaxial) for transport in the system. That is, a Hybrid Fiber Coax system has been integrated into their transport and distribution system.. Among some of the solutions for wired broadband, fiber optic and copper cables are used the most. Cable companies, and even some ISPs, have elected delivery of digital services via copper and fiber with high connection speeds. DSL, cable modem services, and similar offerings are in high demand by businesses, but in Lahore, Karachi and Islamabad, an even larger demand is generated by the consumer. Requests for online gaming, interactive websites, music downloading, online degree programs, and home businesses are driving the demand for bandwidth. The Internet is replacing traditional phones to a certain degree with VoIP (Voice over IP) and other digital phone services. The Internet is also becoming a source of income for some home-business owners.
3.1.1 Copper/Coaxial Cabling
For years, cable systems and local phone companies have been providing voice, data, and video services over copper wire. Initially, this method of delivery was adequate. Before the advent of the Internet, phone and cable providers were a single source, single service -provider, either voice or video. During this time, there were limited channels available. There was no broadband on a cable system, and no dial-up Internet services were available through Internet service providers. The introduction of the Internet has changed these businesses and their service offerings dramatically. As technology advanced, modems became faster and computer users began to desire more speed. Copper has a proven track record in both cable and telephone industries and has shown it can reliably provide services to the end user. Advances in delivery technologies allow high quality of service along copper cabling. This allows a higher bandwidth and bit rate for data to pass along these lines. Compression technologies and digital encoding technologies make it possible for copper lines to carry significantly larger amounts of data than before. The life of a typical coaxial cable system is twenty to thirty years, depending on the type and quality of cable used.
3.1.2 Fiber Optic Cable
In recent years, cable systems and phone companies have begun to use fiber optic cabling to replace or upgrade their existing copper system. Fiber cabling has allowed these companies to realize how fiber delivery is dramatically different from that of traditional copper systems. For instance, an optical network is not subject to interference from outside sources generating EMI (electro-magnetic interference). In the case of a cable system, there is no way to get ingress on an RF signal because it is carried as light instead of as an RF signal along the wire. According to representatives of Corning, fiber is performing very well in its implementations, and the price point of fiber cabling has continued to decline. Fiber is now
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becoming affordable for many small cable companies and service providers. Fiber allows these systems to have a robust network because fiber has virtually unlimited bandwidth. Improvements in manufacturing technology have also made an impact on the quality, price, and use of fiber optics. The useful life of fiber is expected to be seventy or more years because as long as the support material can withstand the elements, the glass is not degraded. This means that fiber has a useful life up to three times that of copper. These improvements have resulted in lower overall cost and increased performance (lower loss/greater distance) and longer useful life.
3.2 Determining the Best Method
When evaluating these delivery methods, it is clear that the network is dependent heavily upon services delivered, price points, and reliability. The next chapter of this study will help in the selection of the most appropriate type of network to meet the needs of the system being built. However, it can be clearly shown that if price and funding are not a problem, fiber is definitely the best choice. Wireless can be used to build a ³data-only´ network, but even then, users will be limited in bandwidth and what services and applications are available. Furthermore, a wireless network needs to be replaced as the technologies driving those systems improve. Wired networks provide an infrastructure, and with improvements in technology and implementation, only the electronics will need to be replaced, not the entire network infrastructure.
4.0 Designing the Network and Overall Plan
Network planning and overall design are critical once funding is in place. The design and services to be offered will dictate the types of technology to be used and will also provide a basis for the timeline and completion of the project. Deployment of different kinds of technology will require different implementation schedules. The project timeline and budget are dictated by technology currently available as well as the type of technology used. As time passes, existing technology gets smaller and is generally reduced in price. According to this trend, some projects can start out with a much bigger budget than necessary if the implementation timeline spreads beyond a six-month to one-year period. New technology can add slightly to the cost of project hardware but can reduce the amount of labor and time required for implementation. The network design and services to be offered are the two driving factors behind the available project budget. The offering of premium services and high quality materials often results in a high cost of implementation. In order to have a successful budget, these premium services and network design must be considered. What services will generate revenue? What services will be desired by the consumer and at what price? What services can be provided with the existing network or proposed network design? What will be the return on investment for this project? Some of these questions should have been answered in the technology plan but should be re-visited to ensure that the network and project will meet the goals and objectives of the plan. It would not be unusual for a network to be designed for specific applications and will then need to be re-designed and optimized because the cost of the project is beyond the scope or constraints of the budget.
Additionally, some funding agencies, especially monies received in the form of grant funds, have
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specific guidelines and certain services that must be provided. In the case of the Philippi network, the USDA stipulated several requirements and functions that needed to be put in place in order to meet the minimum guidelines to receive funding through their grant. These included identifying areas and targeted ³critical´ facilities that would be placed on the network for a period of at least two years at no charge. Further requirements for the grant stated that a public computer lab must be setup and be made available free of charge.
4.0.1 Network Plans
The network plans and design should include: Areas to be served Topography Distance from central office Population density Possible market of services List of services to be offered Timeline for completion Means of expansion Sustainability
These components are tied almost as heavily to the chosen technology as to the services to be provided. The service area dictates which technology can be used to complete the project goals. Defining network service areas can be a difficult process. It is often hard to determine which services an individual will want and whether or not the service will actually be used. In this instance, public meetings, surveys, and questionnaires can help to determine target areas and the extent of the network. Once there are clear, defined boundaries, the formal design process can begin.
4.0.2 Network Applications
Specific areas can be designed based on applications. When addressing needs for a particular area, a custom design can be created to be cost effective and to be deployed rapidly. This service area approach should be used only as a last resort because any changes or deviation from the provided services will result in a redesign or rebuild of that portion of the network. This service model is particularly suitable for geographically challenged areas or areas having a low population density. However, every opportunity should be given to individuals in these areas to receive the same quality and level of service as those in a more populated or geographically desirable location.
4.1 Determining the Area to be served
Densely populated areas and geographic regions which have dense vegetation or numerous hills and valleys are less suited for wireless technologies and better suited for a wired solution. This factor can be seen from the characteristics of the various technologies that provide broadband services. Wireless solutions are bandwidth limited in comparison with the
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long-proven wired alternatives. Furthermore, a wireless solution is strictly dependent upon the environment around it. A wireless solution is perfect for flat locations. It is also ideally suited for providing broadband access to sparse population density. The nature of wireless technology allows it to be deployed cheaply, quickly, and easily, without concern for an actual perfect or optimal design. In a sparsely populated area, wireless technology can be used to meet the bandwidth requirements of users. A wired solution using fiber is best suited for a densely populated area where network bandwidth and usage are at a premium. For a fiber solution to be considered feasible and financially sound, for Philippi, there must be a population density greater than thirty-eight homes per square mile. This is often hard to find in rural areas and small cities, otherwise costs cannot be justified. The calculation above is based on rates and expenses of the network as well as revenues over a five-year period. After the five-year period, the initial investment should be recovered and the network will then begin turning a profit. However, with a public project, it is often unnecessary to see the ROI until twenty years in the future. This difference in a public versus private/corporate project allows a deviation from the calculated population density, allowing for fiber to be deployed in an otherwise less than ideal location. An additional consideration when selecting a service area is the likelihood of customers accepting and using the service. If there is no potential market or desire by the people in an area, there is no need to make the initial investment. Services to that area would be a waste of public or private money. Grant funds, however, often make it possible to provide services when it would not otherwise be feasible. These grants allow public projects to move forward and become a reality which benefits all individuals affected by the project. The number of services offered and the costs of these services set the basis of income and determine the variables to be used for calculating ROI. Grant funds subsidize overall network costs, thereby allowing more services to be offered at affordable cost.
4.2 Determining Network Services to be offered
What types of services will be provided on the network? How many users are projected to use these services? These questions are paramount in obtaining a clear understanding of the underlying network protocols and technologies. If the network is to support voice traffic or broadband phone appliances, there must be a means to provide high Quality of Service (QoS) and reliable resource scheduling. In a typical setup, voice and video are the primary network traffic and take precedence over all other network traffic. All other packets then act on a besteffort method and compete for any unused bandwidth. As bandwidth needs and the number of user¶s increases, the underlying technology of the network may need to change or expand. As shown in the previous chapter, certain network technologies are incapable of supporting a high bandwidth demand or are not reliable enough for sustained long-range communication. There are several things that can be done on a hardware level to mitigate these shortcomings. However, these ³fixes´ are only short-term solutions.
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4.2.1 IP Video
Another changing technology is IP video. Many cable and content providers are starting to offer this service, which is designed for entertainment and is currently one of the largest driving factors in the bandwidth arena. Each network feed or program broadcast can consume anywhere from 6 Mbps to 20 Mbps of available bandwidth (20 Mbps being an HDTV broadcast). So if a cable customer has three IP set-top boxes and is receiving different programming on each box, the customer could be consuming 60 Mbps of available network bandwidth. This assumes that each box is tuned to a different High-Definition (HD) channel. If this application or service is ever desired, current wireless technology will not be able to support it.
4.2.2 Gaming
The gaming industry is also emerging, another reason to look at infrastructure and consider available network technologies. Online gaming for computers and game consoles has become incredibly popular over the last decade. Xbox live service has over two million subscribers and is growing every day. Online gaming places some special requirements or additional demands on the network. Although online gaming can be bandwidth intensive, the primary focus of gamers is on network latency. In other words, how long does it take for the action to be executed? This execution time can be a critical factor when a character¶s life or purchase of an item is at stake. As a solution to the problems of online gamers, network administrators can develop changes in QoS, packet scheduling. Network packet priority can be adjusted to help eliminate some of the latency and allow quick response and execution time.
4.2.3 Voice Services
Another currently popular application is broadband phone service, commonly known as Voice over IP (VoIP). This application uses the broadband connection to the computer and allows a person to place a call over the Internet to a remote location. Typical analog phone service and voice is at 56 Kbps. However, broadband phone services have high standards of quality and will have voice around 192 Kbps, adjustable in increments down to around 50 Kbps. This is an example of an ³on-demand´ bandwidth intensive service. The bandwidth for the customer must be available when the phone is picked up and the call is placed. There are also several other QoS issues that need to be addressed if the phone service received is primary or life-line service. For instance, if the line is rimary, it must be operational at all times, even during a power outage. Currently, when FTTH phone services are provided, a self-contained UPS must be installed as part of the customer premise equipment (CPE), thereby increasing the project cost. These obstacles can make it difficult to find viable solutions, depending on the type of underlying network.
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4.2.4 General Internet Use
The very last, but most used service at this time is basic Internet. Basic Internet use, in this case, is defined as web browsing, instant messaging, chatting, e-mail, newsgroups, and overall application and file downloading. The desire to have high bandwidth is increasing as file size and online content increase in size and complexity. Interactive websites, streaming audio, virtual offices, and telecommuting are four major driving factors in this arena. Websites are now used to market products for businesses providing a new avenue for commerce. Educational institutions have begun offering online degree programs, allowing students to attend a virtual classroom and receive a degree. The Internet has gone from being a tool of knowledge to providing sources of entertainment and establishing itself as a primary route for obtaining information, goods, and services.
4.2.5 Social Trends
Society has become accustomed to having information immediately available. The Internet allows users to have this with the click of a button. The information age has introduced a means for fast acquisition of knowledge and has opened new channels o communications. Ef books, on-line do-it-yourself guides, and various other websites educate users on a variety of different topics and vocations. Research can be conducted without national boundaries for a largescale, efficient, centralized effort. Communities can have a central storehouse of information regarding upcoming events and activities and can learn about potential hazards such as flooding. Cities can have their entire boundaries mapped online in detail. For instance, with the click of a button, anyone can determine which properties are located within a floodplain. The uses of these features are virtually limitless.
4.3 Determining and Designing Applications for Specific Areas
One method for building the network is to design an expandable network that can reach the immediate needs of those that it serves. Often, this is done cheaply to deploy services as quickly as possible. This approach is used as a method to ³get by´ until the ³real´ network can be implemented. This approach often uses wireless technologies to reach geographically undesirable and low population areas. Wireless technology in these instances can provide a minimum level of services to subscribers while still fulfilling the basic needs of the project. A properly designed wireless network will allow for voice, data, and some video to be transported across the network and will allow customers in these areas the same network availability as is received by the customers in the larger, more populated, geographically desirable locations.
4.3.1 Voice and Video Complexities
Voice and video services also introduce an increased level of complexity in network design. Bandwidth demands on video make it imperative that QoS standards and bandwidth priority be assigned at higher levels than for other network traffic. In t e case of h
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wireless systems, latency and distance in network are also critical factors that must be addressed. While wireless can be configured to meet some of these specific application requirements, the restrictions on distance and number of users make it a less than optimal solution.
4.3.2 Fiber as the Network of Choice
The best plan for any network allowing all desired services to be provided is a wired solution. Furthermore, bandwidth availability, equipment life, and overall network reliability push the design of the network toward a fiber-based system. While other wired and wireless technologies work and are proven, a fiber system is the only solution that provides flexibility and ease of future expansion. A fiber system can double as the backbone for other wired or wireless solutions that may be implemented for specific purposes. By having a fiber infrastructure in place, future upgrades can be made easily, and new technology implementations will be well suited to the system.
5.1 Determining how the project will be managed
As with any project, it is necessary to establish a management strategy to ensure that the project progresses towards completion and that all deadlines are met. With larger projects, it is suggested that a management team be created in order to oversee individual aspects of the project. In the case of the Philippi Fiber-to-the-Home (FTTH) project, a management team was created to administer the project. Each member of a management team is assigned to oversee a particular aspect of the project. The Philippi FTTH team was originally divided into three sections, one for construction and materials, one for financing and project budgeting including grant administration, and one for contractual issues and contractor relations. This division of responsibility allowed for efficient review and inspection of the project and provided
enough time for the management team to specialize. Any management team, in order to have an overall picture, must work closely together and provide a weekly summary to all other sections. As a member of the Philippi management team, I was responsible for project design and detailed overview and in-depth analysis of the bill of materials and construction of the fiber plant. This section of the project is typically the most involved and requires almost daily interaction with the contractor and other team members. Also, as part of the construction section, design reviews and changes usually need to be conducted and changes to the system are made accordingly. With a project as large as an FTTH construction for a cable system, many changes take place on a weekly basis. Advances in technology as well as special circumstances that arise once construction has begun tend to crop up and force changes. It is necessary for one member of the management team to have a general understanding of the entire project including finances and contractual issues. That person should be adept at handling design and technology issues and should be able to provide creative and innovative solutions to overcome problems. In order to fully understand how changes and deviations will affect the overall outcome, the management team, in particular the members dealing with construction and
21
materials, must stay aware of changes in technologies. It is not uncommon for an advancement to be made in manufacturing so that a previously expensive piece can be made at reasonable cost. Changes in manufacturing techniques can thus make premium equipment an option. In addition, once technology has been established and manufacturing techniques have been perfected, it is typical that components will decrease in price.
5.2 Determining How the Progress and Status of the Project Will Be Updated and Reported
The Philippi FTTH project is a multi-million dollar project affecting over 1200 cable subscribers. With a project this large, it is important to maintain control of project status and progress. In the beginning, there can be conference calls and meetings on an as -needed basis. Additionally, however, an engineering roundtable should be conducted to keep everyone within the project management team current. Once the project is well underway, weekly progress reports should be given, and any problems that arose during the course of the week should be discussed. Work for the following week should be planned. A member from the project management team should interact with the on-site project manager on a daily basis and should know what is happening in the field. By having daily interaction, small problems can be avoided and issues can be resolved.
5.3 Setting a Schedule and Maintaining Project Deadlines
In order to ensure that the project stays on task, deadlines must be set. Certain milestones must be created to keep the contractors on schedule. Additionally, since the project involves goods and services from various vendors and companies, contracts must be completed and must conform to a timeline to ensure the launch of the system at the correct time. Programmers must be contacted, and network contracts must be signed in order to activate the equipment. Before the testing phase of the project can begin, equipment activation must take place. A carefully balanced timeline must be created so that there is no project element delayed because another portion was not completed on time. The management team must be aware of any potential delays in completion and have plans in place to deal with these delays. In the case of the Philippi project, multiple contractors were used. One contractor was used for the construction of the network, outside plant, and fiber system, and another contractor was hired to construct the Internet Service Provider (ISP). ISP contractors are responsible for building the computer network behind the cable system and must integrate the computer network with the cable network. The project deadlines also serve as a motivational tool for the construction of the project because performance and payment are based on meeting the deadlines. Having a set schedule keeps the crews in the field working towards a common goal. There should be weekly deadlines, monthly deadlines, and a master schedule. Key milestones must be identified to make sure critical tasks are completed on time.
22
5.4 Examining Bills of Materials (BOMs) and Establishing Actual Equipment Needs
Throughout the course of the Philippi project, the BOM needed to be updated, modified, and otherwise reviewed to make sure the goals and objectives of the project were met. From the time the initial RFP and BOM were created, the tec hnologies and equipment have made significant advances. These improvements have often led to reduced costs and increased performance. However, only a careful daily review of these items has ensured that the system will get maximum performance for minimal cost. In addition to a review of the equipment, there is a constant need to see what new technologies are being developed and how these technologies might better suit the needs of the project. For instance, substitution of a high priced piece of equipment may save money in the future by reducing the cost of labor or of other equipment. It is often necessary to exhaust all avenues and equipment options before finally selecting the right piece of hardware. Also, by examining the materials and questioning manufacturers, it is possible to find pieces of equipment that are not necessary to complete the project successfully. Many times, there will be items that can serve as a dual-purpose device, thereby eliminating duplicate equipment. However, it should be made known that multi-function pieces of equipment could potentially cause problems if a hardware failure occurs, as every function depending on that device will not work. Fiber-to-the-Home (FTTH) project took over a year in the construction and design stages. During that period, the project was modified numerous times and several design changes were made. As a way to reduce costs and maximize performance, the splitter, PON, and EDFA configurations were modified and maximized to achieve the best possible results with the lowest cost. One of the largest concerns in the Philippi project was to have the ability to do a remote video broadcast. The initial design included a fiber transmitter at the location where the remote broadcast would occur, plus a fiber receiver in the head -end location. There would be a dedicated fiber which would connect the offices at Philippi City Hall to the head-end facility. In principle, this sounded like it would meet the objectives and was the perfect solution. However, it was also anticipated that Philippi could do remote broadcasts from multiple locations within the system. In order to do this, there would need to be dedicated fibers at each location so that the fiber transmitter could properly communicate with the head -end. This would drive up labor costs, increase the complexity of the network and its management, and possibly drive up the cost in equipment if additional transmitters were purchased.
5.4.1 Equipment Considerations
Other considerations were the number of splitters, the types of ONTs used, the placement and type of drop enclosures. There was a careful analysis done to determine whether spliced or connectorized drops should be used and what the benefits would be. It was determined that, in the case of Philippi, connectorized drops should be used. These drops allow more network test points. Easier and quicker subscriber turn-up Reduction of the number of times a fiber splicer needed to open an enclosure This has resulted in a stable, reliable network because there is little chance of human error or destruction of spliced fibers because the enclosures should not be opened after the initial splices are made.
23
6.0 Informing the Publi and Marketing
Informing t publi and pot ntial consumers about project status is necessary in any project£ but it is critical in t e case of a public project¤ The Philippi FTTH project is funded by both public grant funds and loans/bond issuances which must be accounted for. Progress and project information must be reported not only to the funding source, but also to the public at large because they are stakeholders. Marketing is a key aspect because ultimately the purchase of goods and services creates the revenue that will be used to pay off the debt incurred for the construction of the project. While many large companies have excellent marketing for mediocre services and can generate large profits, public entities and government agencies typically have excellent services with poor marketing. The City of Philippi, being a governmental agency, has several avenues through which to creatively market goods and services. By providing the public information and essential details, consumers are able to make the most responsible and informed decision possible. Information dissemination and marketing are often overlooked because the primary focus of the project is construction. Government agencies are not accustomed to marketing goods and services. A typical good or service provided by the government is created to address a need, and it is up to the consumer to make use of that good or service. However, in the case of technology and newer goods and services, it is often hard to determine what is needed and what good or service is the best choice. Project status and projected outcomes should be publici ed to keep public interest in the project high and to establish desire to acquire goods and services. The progress reports released to the public will also serve as documentation and corroboration for present and future funding sources. This is also a perfect time to release details about plans for expansion and for goods and services that will be offered as a result of the project. Educating the public on the underlying technology will also be critical to understanding the system and acceptance of what the network can do. ¡ ¢ ¡
7.0 Represented in every l yer of t e FTT
Feasibility consultants
val e chain
ROW owner
Network design
Network construction
Network owner Wholesale provider Retail provider
Project management
Content provider
Content aggregator
Financial consultants
Our members include service providers (RBOCS, CLECs, Municipalities, and Rural LECs), network design and construction companies, financial consultants, and equipment manufacturers.
2
¥
Copper // CO/HE Fiber
CO/HE /
Old
Optical tworks, optimiz d for oice, ideo and data
ote: network may e aerial or underground
An OAN in which the ONU is on or within the customer¶s premise. Although the first installed capacity of a FTTH network varies, the upgrade capacity of a FTTH network exceeds all other transmission media.´ OAN: ONU: OLT: Optical Access Network Optical Network Unit Optical Line Termination
OAN
//
CO/HE ONU
OLT
CO/HE
§ § ¨ ©¨§¦
, z df
CO/HE /
24 kbps - 1.5 Mbps
§
§¦
19 Mbps - 1 Gbps +
25
8.0 Why FTTH?
Enormous information carrying capacity Easily upgradeable Ease of installation Allows fully symmetric services Reduced operations and maintenance costs Benefits of optical fiber: a) b) c) d) e) Very long distances Strong, flexible, and reliable Allows small diameter and light weight cables Secure Immune to electromagnetic interference (EMI)
More capacity*
200
150 Gbps 100
50
0
!
Twisted Pai
ax
ultim d
Single-m de
e
* Ty i
l y t
ility f
100
li
#
#
%
$# "
26
Longer distances*
100 90 meters 80 70 60 50 40 30 20 10 0
Kil
&
Twisted Pai
-axial
f 1G
ultim de
Single -m de
* Ty i
l i t
y t
ility
Symmetric services
Outbound Internet bursting to 80Mbps Inbound Internet (download) averaging about 3540Mbps Upstream is consistently twice the download
27
9.1 Fi er versus Copper
y A single copper pair is capable of carrying 6 phone calls A single fiber pair is capable of carrying over 2.5 million simultaneous phone calls (64 channels at 2.5 Gb/s) A fiber optic cable with the same informationcarrying capacity (bandwidth) as a comparable copper cable is less than 1% of both the si e and weight
y
y
Fi er versus copper
Glass
y y y y y y y Uses light Transparent Dielectric material-nonconductive EMI immune Low thermal expansion Brittle, rigid material Chemically stable
Copper y y y y y y y y Uses electricity Opaque Electrically conductive material Susceptible to EMI High thermal expansion Ductile material Subject to corrosion and galvanic reactions Fortunately, its recyclable
28
9.2 How do optical fi ers work?
Core y Carries the light signals y Silica and a dopant Cladding y Keeps the light in the core y Pure Silica Coating y Protects the glass y Acryl ate (plastic)
CORE CLADDING 245 m 125 m 8 - 62.5 m
Len Ray
COATING
How do optical fi ers work?
Optical fibers work on the principle of total internal reflection Light waves (³modes´) are reflected and guided down the length of an optical fiber 4
1 2 3 4 Fig 9.1
1 2 3
Total Internal Reflection:
One of the quality of any optically transparent material is the speed at which light travels within the material, i.e it depends upon the refractive index n of the material. The index of refraction is merely the ratio of the speed of light c in vacuum to t e speed of h light v in that material. Expressed mathematically, c n! v
29
The amount and direction of reflection or refraction is determined by the amount of difference in refractive indices as well as the angle at which the rays strike the boundary. At some angle of incidence, the angle of refraction is equal to 90o. this angle of incidence is called the critical angle c. By Snell¶s law
n2 Air
2
c
1 n1 Water, Glass or Plastic
n1 sin 1 = n2 sin 2 from Fig. 9.2, when thus, n1 sin c =
1 2
=
c,
or
= 90 sin c = n2/n1
2
Fig 9.2 For incident angles equal to or greater than the critical angle, the glass ± air boundary will act as a mirror and no light escapes from the glass. For glass ± air boundary, we have n2 1.0 or c = 41.8o sin U c n1 1.5 Angle of incident should be greater than critical angle for total internal reflection.
' '
9.3
Types of lasers used
There are two laser technologies that are used for nearly all single mode communications applications Fabry-Perot (F-P) lasers o Lower in cost, lower in power o Poorer wavelength stability Distributed Feedback (DFB) lasers o Higher cost, higher power o Excellent wavelength stability o Excellent temperature stability o Internally modulated o Good for moderate powers and distances Ultimate today for quality in broadcast applications Vertical Cavity Surface Emitting Lasers (VCSELs) Coming technology, promises lowest costs
30
Wavelengths used for Single Mode Fiber (long distances) communications
1310 nm Usually lowest cost lasers Used for shorter broadcast runs and short to moderate data runs 1550 nm Can be amplified with relatively low-cost erbium doped fiber amplifiers (EDFAs) Lasers are fabricated on a number of different wavelengths (about 1535 ± 1600 nm) for wave division multiplexing (WDM) applications Slightly lower fiber loss at 1550 nm 1490 nm Increasingly popular for downstream data in 3 Cannot be amplified as easily Somewhat higher device cost
systems.
9.4 Single and Dual Fiber Systems
Single Fiber Downstream broadcast* on 1550 nm Upstream data on 1310 nm Downstream data on either 1310 or 1490 nm* depending on system * Downstream data can be carried at 1550 nm if not used for broadcast Advantages Less fiber deployed Fewer optical passives (taps or splitters) Fewer labor-intensive connections
Dual Fiber
Various plans, usually one fiber will be used for downstream and one for upstream, or one will be used for broadcast and one for data. Sometimes one will be used for specialized services, such as returning RF-modulated data from set top terminals
31
Advantages o Simplifies terminal passive components o Somewhat lower signal loss
CO/
//
Technical considerations
10
Opti
l fib
63261 541 32
1 9
T port - ATM? - Eth rnet?
Philosophy - et il - Wholesale
l
53 2584 2 0
60 483 02 23 02 03 7 ( ) 2 6413
A hit tu El t i ) - PON? - A tiv ? - Hyb i ?
32
Transport - ATM
53 byte cell 5B Destination Header Data Next cell
Ted Kathy Jeannie Susan Joy
Alice Jim Travis Kyle Craig
Ethernet has its roots in office data systems Connectionless-oriented, with excellent efficiency Packets are transmitted individually, requiring resources only when they are being transmitted
Transport ± Ethernet
Destination Address Type/length
8
Preamble & SFD Source
6
Address
6
2
Data and pad
Up to ~1500 bytes
Frame Check
4
Packet of data
33
Opportunistic Data moves During idle times Ted Kathy Jeannie Susan Joy
Opportunistic Data Alice Jim Travis Kyle Craig Nothing to send
When data is available, it gets the first available chance to be sent.
Ethernet has its roots in office data systems Connectionless-oriented, with excellent efficiency Packets are transmitted individually, requiring resources only when they are being transmitted
Transport - ATM? - Ethernet?
Philosophy - etail - Wholesale
Architecture Electronics) - PON? - Active node? - Hybrid?
Opti al fiber and lasers
@
EFM standard split ratio, 10 and 20 km optics
A
CO/
//
Technical considerations
34
10 Selecting and Evaluating Technologies to Meet Network Plans
After the type of network is chosen, it is necessary to see which technologies are available and weigh the benefits each type will provide. In the case of the Philippi broadband project, fiber was chosen as the transportation medium and network backbone. Some would argue that this was the final decision, and that nothing mo re needed to be decided about the network. However, nothing could be farther from the truth. Actually, choosing fiber as the main source of transport was the easiest decision. This choice has very little to do with underlying technologies and available options as far as the entire optical and electronic network is concerned. Fiber allows for unlimited bandwidth, essentially a century of usable life, and the ability to add and upgrade services in the future. However, following the determination of a transport method comes the task of deciding which technologies will be used and what services will be provided. The first goal of the Philippi project was to provide video and data services. A secondary and future goal is to provide voice, thereby using the ³triple-play´ that is talked about with the Fiber-to-the-Home suite of services. The triple play suite would provide voice, data, and video services to subscribers over a single fiber and would provide these services to the customer using a single device. By offering a tripleplay suite of services, packages and incentives can be created to target customers and leverage current technologies to maximize profits. After investigation, there were three main types of technology considered for the Philippi project: B-PON, E-PON, and GPON. Each of these standards and technologies can meet the needs of the project in terms of verall outcomes. However, they accomplish this in vastly different ways.
10.0.1
Basic PON Understanding
Before explaining the various available options, it is necessary to understand the underlying network and terminologies. A PON network is actually a Passive Optical Network, meaning there are no active components located within the outside plant network. To further describe the PON architecture, it can be viewed as a simple network of fiber connected to equipment located at a central distribution facility (head-end) and a subscriber facility where it is connected to another piece of equipment (CPE or customer premise equipment). The customer premise equipment consists of an ONT (Optical Network Terminal) and a power supply. The ONT device is responsible for taking the light signals and converting them into services and signals that can be used by the customer. The power supply provides DC voltage to the ONT and generally contains a attery to provide backup power for the voice and data services. The fiber network requires no maintenance or power to outside components. All active components needing power and monitoring are located at the extremities of the network (the head-end facility or the subscriber/customer facility), commonly referred 35
to as a ³home-run´ network.. This type of network minimi es the need for truck rolls and service calls because problems can be taken care of directly at the head -end facility or central office location.
10.1 E amining B PON Architecture
The B-PON (Broadband PON) architecture is probably the oldest of the three mentioned above and is an off-shoot from the earlier A-PON fiber architecture which is the ATM (Asynchronous Transfer Mode) architecture from the 1980s. The B-PON architecture is capable of delivering RF video, voice service via POTS (plain old telephone service) and data using Ethernet. This architecture is the most basic and meets the needs of the project.
36
Figure 2: B-PON Table
The B-PON standard allows for 870 Mhz video bandwidth by using RF video overlay and placing the video content on the 1550 nm wavelength [1][3]. B-PON also provides a 622 Mbps downstream data connection and a 155 Mbps upstream connection. Each node/connection is split between 32 subscribers [3]. To get an accurate picture from a subscriber standpoint, a little math must be done. Each subscriber on a node will have an effective bandwidth of 19.4 Mbps downstream and 4.8 Mbps upstream. This bandwidth is sufficiently fast; however, as bandwidth and user needs grow, this architecture will become obsolete quickly if not enhanced using other available technologies. The architecture has been standardized to allow one vendor¶s ONT to work on another system which has another vendor¶s OLT (Optical Line Terminal)[1]. The OLT is located at the head-end facility and provides the data and phone connection to the network. One OLT can support several hundred ONTs. This ONT interoperability ensures that there is competition and equipment availability in the market.
10.2
Examining E-PON Architecture
E-PON (Ethernet PON) architecture has been approved by IEEE and meets Ethernet standards [2]. This architecture is very similar to that of B-PON in equipment and operations but distinguishes itself drastically when it comes to network operations, components, and speeds. This architecture is able to deliver voice, data, and video. E-PON uses the same three delivery methods as B-PON to deliver services to the customer premise equipment: Ethernet port, RF Video port, and POTs ports [3]. One key distinction between B-PON and E-PON is the type of network and the speeds for data transfer. While most of the available PON standards are ATM based, E-PON is Ethernet based [2]. E-PON uses 802.3 Ethernet frames (packets) to allow for a 1 Gbps upstream and downstream rate over the network. Upstream and downstream bandwidth remain at constant symmetrical rate of 31.25 Mbps per subscriber. Another difference in this architecture is the configuration and setup of the network. The E-PON standard allows placement in the field of active components which allow for a bigger network because these components remove the 20-kilometer (20K) limitation found in traditional PON systems. A typical configuration of this type of network also uses a 1x8 splitter, which results in higher available bandwidth to the customer. Using a 1x8 splitter, an E-PON network fiber can serve eight homes through a single fiber going back to the head-end facility.
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Figure 4: E PON Table
This improved bandwidth does come at a cost. Using 1x8 splitters in this configuration would take four times as many fiber lines to provide services to customers using a traditional 1x32 B-PON configuration. Additionally, by having active components in the field, there is a higher maintenance cost because technicians will need to visit multiple locations to troubleshoot and correct problems/errors in the network.
10.3
E amining G-PON Architecture
The G-PON (Gigabit PON) architecture is fairly new and is an evolved form of BPON. There are major differences in this architecture from both B-PON and EPON. While the current G-PON solution supports triple play (voice, data, and video), it does not have the same features and flexibilities of the other architectures. The GPON standard provides an Ethernet port and POTS ports but does not provide an RF video port. If the G-PON network is chosen, and if adhering strictly to the defined standard, the only type of video service that can be delivered is IP video. This solution offers some adapters to convert IP video to RF video. This provides customers with the basic ³analog´ type cable TV services. The remaining option is for every TV to have IP-based cable converter box placed on every TV within a subscriber¶s residence. This requires a CAT5 connection, thereby increasing the cost of equipment to operate the system and requiring the operator to maintain an inventory of these settop boxes.
Figure 5: G-PON Table
38
The G-PON architecture is still ATM-based and follows the same limitations and restrictions as a B-PON system [3]. All active equipment is located at the central distribution facility, and the system is entirely passive. The G-PON network differs in data transfer speeds because it has an available 2.488 Gbps of bandwidth downstream and 1.244 Gbps upstream [1]. This network is asymmetric in bandwidth, just as with B-PON, and it uses the same distribution mechanisms and configuration. The use of a 1x32 splitter keeps the fiber count down and allows for a less expensive deployment of network services because a single fiber can sustain up to 32 customers. It should be noted that although traditional G-PON does not support RF video overlay, some vendors, including Motorola, are adding this support to their product line and G-PON solution. These vendors are designing and shipping a G-PON ONT complete with a triplexer, which enables the ONT to have an RF video overlay, providing the ONT with telephone, RF video, and Ethernet ports. This is significant because by implementing this feature, traditional RF head-end facilities can be reused, and there is no need for an IP-based video head-end. Furthermore, this results in increased bandwidth for data services and allows more video services to be added to the system.
10.3.1
B-PON and G-PON Differences
The differences in the various PONs can be confusing. However, it should be noted that most operate on the same basic principles. A key difference in data services and network transmission between G-PON and B-PON is the encapsulation. BPON packets are based on ATM encapsulation, which results in a tremendous amount of overhead. In contrast, G-PON encapsulates packets much more efficiently. GEM or G-PON Encapsulation Mode is a dramatic improvement over the ATM encapsulation of B-PON. Furthermore, this encapsulation is more efficient than that of EPON. The G-PON encapsulation method has approximately 4-5% overhead, with E-PON having up to 50% overhead [3]. This is a significant improvement, especially when bandwidth, reliability, and advanced services are considered. The data speeds and increase in bandwidth from B-PON to G-PON are astounding. The math for GPON is simply 2.488 Gbps downstream divided by 32 and 1.244 Gbps upstream divided by 32. That effectively results in a 78 Mbps downstream bandwidth and a 39 Mbps upstream bandwidth per customer. G-PON continues to support legacy systems and TDM services such as DS1s, and it interfaces to Class-5 switches.
39
11.0
Architecture PON Network
Passive Optical Networks (PONs)
Shares fiber optic strands for a portion of the networks distribution Uses optical splitters to separate and aggregate the signal Power required only at the ends
Active Node
Subscribers have a dedicated fiber optic strand Many use active (powered) nodes to manage signal distribution
Hybrid PONs
Literal combination of an Active and a PON architecture
OLT
// / / //
//
//
//
ONU
Optical splitter 1x16 (1x2, 1x8) 1x32 (1x4, 1x8)
//
40
Architectures ± PON (2) (A-. E- or G-)
1550 nm broadcast (if used)
OLT
1490* nm data
//
// / / //
1310 nm data
/
//
ONU
//
* Data
Architectures ± Active Node
OLT 1550 nm broadcast
/
/
/
/ / /
ONU
/
Data, 1310 or 1550 nm (depending on distance) on separate fibers
/
/
Single fiber, 1550 broadcast, 1310 bidirectional data
B
C
ay be transmitted at 1550 nm if not used for video
Up to 10 m
41
Time division multiplex (TDM) ± each subscriber¶s data gets its turn.
T
//
D
//
/ / //
T
Tom
D
Dic
//
//
Box on side of home separates out only the data bound for that subscriber. But the fear is that someone will fool his box into giving data intended for another subscriber. Solution is to encrypt the data.
arry
Time division multiple access (TDMA) ± similar to downstream, with gap for laser start/stop
//
T
D
//
D
Tom Dic
/ / //
//
//
arry
Due to the physics of the network, Harry¶s data flows upstream but does not come to Tom¶s box, so Tom cannot see Harry¶s data
Data Flow and QoS
E
42
If Dick has paid for more bandwidth, he ets more
/ / /
/
/
arry
12.0
Telephony Considerations
Depending on whether the FTTH system is based on ATM or Ethernet, the basis of the phone technology is either conventional swit ched circuit or the newer VoIP
12.1 Conventional Switched-circuit Telephone
During conversation, line is Continually tied up in both Direction To other class 4 s And 5 switches
.. .
Bob
.. .
Concentrato r (DLC)
Switc h
Ted Donald
Switched Circuit Telephony
F
If Tom¶s packets need hi her priority e.g., telephone), they go first
Carol
Alice
43
P
F
I
G
H
H
/
T D
/
T Tom D Dic
12.2 Example VoIP System
During conversation, line is shared With other data packets on each Side of the router Telephone Packets Other data Packets Carol Customer Gateway Router Data
To PSTN Bob Customer Media Data Softswitch Gateway
Gateway
(Switch)
Alice Customer
Ted Customer Gateway
Donald
Data Customer
Gateway Data
Data
Gateway
One Form of Voice on Internet Protocol (VoIP)
13.0
Video
Video is a popular service, which is a good basis for any new entrant FTTH provider. There is one way to provide video on cable and satellite (broadcast) and one way to provide video on DSL (IPTV). There are two ways to provide video on FTTH (broadcast and IPTV). The market place can sort out the use of each, to the benefit of the subscriber. We will describe the differences.
Can send video several different ways on FTTH Broadcast (cable TV standards)
Analog Digital Cable TV good engineering practice is 47-48 dB C/N FTTH can achieve 48-51 dB C/N Benefit from high volume and plethora of applications of cable boxes RF return support for STTs
44
14.0
IPTV ± TV transmitted over Internet Protocol
Feasible, and some people are doing it in place of broadca st Bandwidth hog, but statistics can work for you Interesting hybrid model awaits hybrid STTs, but can give the best of both worlds
14.1 Ways of transmitting video
Other channels Baseband analog video white Modulated analog video Analog Optical transmitter Broadcast optical network
Black sync
Analog RF modulator
Encoder
Ch 2 55.25 Ch 3 61.25
MP G-2 Transport Stream
Digital Compressed Video ...101101001... Digital RF OR
modulator
Q
Place MPEG packets in IP packets
L2/L3 Switch
Other data sources
...
Digital Optical transceiver Digital optical network
45
14.1.1
Ways of transmitting video ± wave division muxing
14.1.2 Ways of transmitting video ± broadcast headend
IR
Analo hannels
...
Analog RF modulator, stereo, scrambler Analog RF modulator, stereo, scrambler Transcoder, digital RF modulator, upconverter Transcoder, digital RF modulator, upconverter
IR
Linear (broadcast, analo ) optical transmitter To distrib tion plant Amplitude Analog channels Spectrum diagram: h 2 h 3
...
i ital hannels Earth station
IRT
server
igital channels
Freq ency
RF return signals
46
14.1.3 Ways of transmitting video ± broadcast subscriber
Analog broadcast,
Linear)
eceiver, one per optical
Endpoin t
Optic
sI n
14.1.4 Ways of transmitting video ± IPTV headend
. . . Analog Channels
IR D IR D Encode r
Encode r Packet -
. . . Digital Channels
IR T
IR T
Transcode r
Transcode r
VOD server
Other data Source s
T T
R
S
Set top terminal Tuner Demod
Select channel by Selecting frequency (Opt. F eturn)
Descrambing
Subscriber's TV
...
Not required Analogfor only Service )
Digital binary) optical Transceiver part of outer)
To groups of Subscribers
Downstream data ...
H D H D
...
47
14.1.5 Ways of transmitting video ± IPTV subscriber
Digital (binary) optical Transceiver, one per Endpoint
Optics FTTH interface
Select Packets data for Subscribe r Inhome Routin g
Other Applications
.. .
H
D
H
IP Set top terminal
Packet request Decodin and Selectio g n Select "channel" by requesting to join a Multicast group or requesting a From a stream VOD server Subscriber's TV
14.2.0 Ways of transmitting video ± IPTV unicast (VOD)
Router B
Router A (Headend )
(Network ) Router C
Router E
In-home Routing
VOD server
Router D(NID ) Progra Strea m m Progra Reques m t
In-home Routing
In-home Routing In-home Routing
Set top Terminal
Subscriber's TV
48
Route B Router
Encoder
A Headend) Progra m Packets Router C Network)
. . .
Transcoder
Router E
In-home Routing
Larry's STT And TV
1 multicast Video program
Router D NID
In-home Routing
Moe's STT And TV
In-home Routing In-home Routing
STT
Curley's TV
14.2.1 Ways of transmitting video ± IPTV multicast
Router B Progra packet m s Router (network C )
?
Encoder . . .
Router (headend A )
?
Router E
In-home routing
Larry's STT and TV
Transcoder
1 progra video m
Router D Ha
?
In-home routing
Moe's STT and TV
Progra request m s
lf
In-home routing
?
In-home routing
STT
Curley's TV
49
14.2.2 Ways of transmitting video ± IPTV multicast
Router B
Encoder . . .
Router A (headend)
Program packets Router C (network)
Router E
In-home routing
Larry's STT and TV
Transcoder
?
1 video program Program requests
? ?
Router D (NID)
In-home routing
Moe's STT and TV
In-home routing ? In-home routing
STT
Curley's TV
50
15.0 PON link budgets
A system is limited in the distance you can send signals and the maximum number of times you can split the signal to go to different subscribers. The main problem is usually that the signal level drops too low to be usable. Other considerations sometimes dominate.
Fiber loss per km is 0.25 dB 1550 nm) to 0.4 dB 1260 - 1360 nm)
//
//
Half
Single-mode Multimode Co-ax Twisted Pair G200 150 100 50
Every time the signal is split two ways, half the power goes one way and half goes the other. So each direction gets half the power, or the signal is reduced by 10log 0.5) =3 dB. Practical loss is 3.5 dB nominal, so every two-way split costs about 10 km distance @ 1310 nm
Broadcast analog video often sets the budget Maximum practical level without SBS issues ~16 dBm (long spans) Minimum receive level for 48 dB C/N ~-5 dBm Link budget is ~21 dB, a bit more if you are careful At 1550 nm, fiber exhibits loss of about 0.25 dB/km, so maximum distance without amplification is ~80 km Requires good externally-modulated transmitters (available) Each two-way split results in a loss of nominally ~3.5 dB of level, assume 4 dB worst cases. Thus, each two-way split costs about 16 km distance
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Analog video link budgets
Split Nom. splitting loss Avail. fiber loss Nom. Distance (dB) (dB) (km)
7 10.5 14 17.5 21 11 7.5 4 2.5 -1 44 30 16 10 -4
4 8 16 32 64
Notes: based on nominal fiber and splitter loss, not worst case. Practical distances are less. Includes 2 dB for connectorization loss, 1550 nm externally modulated transmitter
Gigabit EPON link budgets (example, based on GBE best case )
Split 4 8 16* 32 64
Nom. splitting loss (dB) 7 10.5 14 17.5 21
Distance (km), 40 km GBIC 14 4 -
Distance (km), 70 km GBIC 44 34 24 14 4
Notes: based on nominal fiber and splitter loss, not worst case. Includes 2 dB for connectorization loss, 1310 nm DFB laser * EFM standard split ratio, 10 and 20 km optics
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