It gives this book a uniquely global perspective, as it drawing on best-practices, architectures and network trends rooted in the real-world. Because the authors are so distributed all over the world, this presents logistical challenges. Getting together for physical meetings is notoriously difficult. On conference calls, someone invariably has to draw the short time-zone straw and get up in the early hours of the morning or stay up late with a strong cup of coffee. Our editors, contributors and reviewers are spread out over the globe too. But with a good broadband connection, distances are no longer as great a problem.
A quick, jitter-free VoIP call is cheap and painless when needing to bounce ideas off somebody. Sending large files to a reviewer is a snap with a zippy upstream connection.
truman boyes: 1 Books available | soafootxelama.ga
And when you need a break from work, dialing up last week? This book would have been much shorter and less helpful without the networking experience of our many technical reviewers and readers. Particular thanks to Chee Teoh and Jonny Martin for their support, suggestions and expertise.
Finally we owe much to our families and friends who saw less of us during the entire year that it took to write, edit, and review this book. Dylan Greene would like to thank his wife, Luciana for all of her time spent listening to him talk about broadband architecture, which was promptly followed by her invaluable support editing chapters; his parents, Drs.
It may appear in backmatter instead. Discuss at RTP. His role with Juniper is to assist customers with the design, test, build and deployment phases of broadband access and backbone networks of all sizes. He currently lives in the United Kingdom although he most often can be found within one of Europe? Dylan is a consultant with the Juniper Networks Professional Services group.
He has over a decade of technical networking experience, having worked in a variety of environments from Tier 1 carriers, Greenfield providers, financial enterprise networks, and mobile carriers to aerospace and defense projects. Prior to Juniper Networks, Dylan? Truman Boyes has designed and implemented large-scale carrier networks for the past 10 years.
He is a Professional Services Engineer for Juniper Networks in Asia-Pacific where he is implementing next- generation networks that cater to larger subscriber growth and provide resiliency. Truman is active in numerous Internet and security related technical forums and currently lives with his partner in Wellington, New Zealand. Historically, the limited range of different services which could be offered over a single local loop access has been one of the largest obstacles Telcos faced when attempting to expand their service portfolios. As multi-service broadband network architectures continue to evolve, as described in this book, Telcos can deliver a far richer range of voice, video and data services than ever before.
Historically, only a limited range of highly reliable, lower bandwidth services could be offered over conventional copper twisted pair phone wires by telecom companies. This book discusses the architectures behind these services, beginning in this chapter with a brief history of broadband. The mid s was a critical time in the development of the telecommunications industry; many innovations were realized into real world deployable implementations during this period, including the rollout of SONET optical services, ATM, Frame Relay and ISDN, to name a few..
These services were all emerging during a particularly challenging time in the Telecom market.
Incumbent Telephone companies were facing slowing and eventually peaking revenue growth from legacy services that could only be remedied by developing new business lines and services to generate additional income. The legal landscape was changing as well, with significant emphasis and debate focused on deregulation and allowing competition in the historically tightly held carrier local-exchange marketplace. At the same time as incumbent telephone companies were dealing with these issues, cable operators MSO were facing a similar set of challenges.
Faced with slowing revenues and growth, the cable operators, who already owned extensive high bandwidth infrastructure, were prompted to seek new areas of growth for their own businesses.
- Fire Study (Study, Book 3)!
- broadband network architectures designing and deploying triple ...!
- Trust in Numbers: The Pursuit of Objectivity in Science and Public Life;
- Inscriptions: The Athenian Councillors (Athenian Agora vol. 15)!
This created an extremely competitive environment in the mid to late s between cable operators and telecommunications companies, each wanting access and revenue from each other? This access network, a decades and sometimes century old copper network was initially primarily oriented towards delivering low bit rate, highly reliable data and circuit based voice services. Each approach, HFC and the copper access networks, had sufficiently unique characteristics thereby creating obstacles to each operator?
However, there were significant motivations to drive each type of operator? Cable operators sought to deliver data services to customers and telecom companies to deliver video. Telecom carriers saw a chance to deliver lucrative broadband video services utilizing the unused spectrum in the existing global copper infrastructure.
It was thought that high data rate services such as video on demand would drive customer demand, consequently funding the Telecom industry? At the same time, around the period during which these initial ideas were coming into focus in the telecommunications industry, the Internet was being adopted by the mass market at an exponential rate. This created the opportunity for the expanded adoption of a newly developing access technology; DSL.
The initial focus of ADSL during its inception was to support video streaming to the home, which allocated most of the radio spectrum in the downstream direction, hence its asymmetrical nature. After early Video on Demand VoD trials and the obvious booming market demand for Internet bandwidth, there was enough momentum to expand the industry?
Copper The most common telecommunications service, the POTS Plain Old Telephone Service , available to millions of customer premises worldwide, is normally provided to the user via a 24 gauge twisted pair copper wire from the Telco? In copper wire based transmission media, output power decreases exponentially as a function of distance, which creates loss.
Initially these circuits were only intended to carry voice traffic, which would often have to be trunked between Telco exchanges to provide long distance services. To conserve bandwidth on the trunks between exchanges and some residential areas, individual POTS subscribers were typically connected through? This enabled efficient frequency multiplexing on trunk connections between Telco exchanges, as many of these 3,hz?
In a best-case installation scenario, the data capacity of a traditional POTS line due to these bandpass filters is around 53KBps? While Telcos have been able to offer other data services over the same copper infrastructure using legacy modulation and encoding techniques, these services are typically quite distance-dependant and have severely limited bandwidth.
To maximize the distance a signal can be accurately transmitted, copper wires are typically bundled in? The higher the number of twists per a given distance, the greater the effect and thus distance a signal can be transmitted. See Table 1. Sidebar: Sampling Theorm Sampling is the name for the process of turning a signal into a numeric sequence. The Nyquist-Shannon sampling theorem, commonly known simply as? The term? The theorm proves that evenly distributed samples create an accurate representation of the original signal if this bandwidth is less than half of the sampling rate performed on the signal.
This basic theory can then be used in calculations to determine the ability of a given media for example, 24 gauge unshielded twisted pair copper wire , based on various characteristics including the fact that a signal? Table 1. Originally developed at Bellcore now Telcordia , the ADSL specification began to receive serious attention from the Telcos as a means to compete with the cable HFC networks, who were threatening to provide data services to legacy Telco subscribers.
The Bellcore ADSL service was capable of offering high rate data services and analog voice services over existing Telco copper facilities. ADSL has some significant differences from HFC service, mainly that it provides dedicated resources and bandwidth to each subscriber, while HFC, because it is a shared medium, spreads bandwidth across multiple users. Even though HFC networks could natively carry larger amounts of bandwidth over the coaxial cable infrastructure that cable companies had deployed, this bandwidth has to be shared among multiple users.
ADSL provides a dedicated circuit and bandwidth for each user. Therefore, even though coax cable inherently provides more bandwidth, there is a crossover point where it becomes more efficient to provide a higher per-user bandwidth over ADSL than cable, as is seen in the result of the worldwide adoption of DSL technology and services. DSL enables passive transmission of voice and data service over a single copper twisted pair cable. Using simple and inexpensive bandpass filters on both ends of the copper wire, analog voice service and high speed data service are simultaneously provided to each customer premises without much expense to the Telco or end subscriber.
As seen in figure 1. These are filtered out using a bandpass filter before reaching the DSL modem to reduce the RF interference to the modem. Insert figure 1. These bodies proceeded to standardize the ADSL specification. CAP, which was the most commonly deployed modulation technique, is a single-carrier modulation scheme that uses a wide passband i. DMT on the other hand, uses multiple, discrete carriers, achieving higher bandwidth rates by using many narrowband channels.
While both techniques have different modulation characteristics, they are both capable of providing the same service or interface to the higher layer protocols. A higher layer protocol is one further up the OSI stack. It was felt that single channel CAP modulation might not be able to deliver high rate, multi-channel video services as efficiently as DMT. Towards the end of the year, the ADSL Forum steering group was formed, with members representing a diverse group of Telcos, equipment manufacturers and other interested parties.
Even though early implementations used the well understood and common thus inexpensive CAP, there were arguments that it would be difficult to scale the modulation scheme up to greater bandwidths over time due its single carrier implementation. There was also concern that CAP was more vulnerable to interference.
Designing and managing networks
The DMT standard initially called for sub-channels, each 4 kHz; 1. Phase shift keying or digital phase modulation is very similar to frequency modulation but instead of changing the frequency of the transmitted waveform, the phase is changed to represent digital data. Using Quad PSK, the waveform can perform 4 unique phase changes 4 symbols.
These 4 symbols can thus represent 2 bits of data per symbol, which effectively doubles the bandwidth of the carrier modulated at a given frequency. Figure 1. These windfall contracts later led the rest of the market towards standardizing on DMT, thus ending this important historical battle between modulation techniques.