Internet Access via Cable TV Network

Internet Access via Cable TV Network

Course Seminar Report

in

Electronics and Communication

Submitted By

Ankur Desai (USN: 2GI08EC015)

Anisha Nayak (USN: 2GI08EC014)

Anish Kumar (USN: 2GI08EC013)

Under the Guidance of

Prof. N. S. Sirdeshpande

GOGTE INSTITUTE OF TECHNOLOGY, BELGAUM

2010

This is to certify that students of 5th semester A division with above mentioned names and

USN have successfully completed the course seminar titled “Internet Access via Cable TV

Network” and have orally presented the same. This course seminar report is submitted to

partially fulfill the requirement of Outcome Based Education (OBE) practiced in the institute.

Name and signature of examiner with date Marks (out of 50):

Contents

Synopsis Different Types of Internet Access Cable TV Networks Working of Cable Internet Cable Modem Cable Modem Terminating System DSL vs Cable Internet Advantages Disadvantages Conclusion

Synopsis:

Internet Access through Cable TV Network is a form of broadband Internet access that uses

the cable television infrastructure. Like digital subscriber lines and Fibre to the premises,

cable Internet access provides network edge connectivity (Last mile access) from the Internet

service provider to an end user. It is integrated into the cable television infrastructure

analogously to DSL which uses the existing telephone network. The cable TV signals are

often removed by filtering at the line tap outside the customer's premises. Cable TV networks

and telecommunications networks are the two predominant forms of residential Internet

access. Recently, both have seen increased competition from fibre deployments, wireless, and

mobile networks.

Cable Internet access is the principal competitor to DSL and is offered at a range of prices

and speeds overlapping that of DSL, but tends to concentrate more on the high end of the

market.

Broadband cable Internet access requires a cable modem at the customer's premises and a

cable modem termination system at a cable operator facility, typically a cable television head

end. The two are connected via coaxial cable or a Hybrid Fibre Coaxial (HFC) plant. While

access networks are sometimes referred to as last-mile technologies, cable Internet systems

can typically operate where the distance between the modem and the termination system is up

to 100 miles (160 km). If the HFC network is large, the cable modem termination system can

be grouped into hubs for efficient management.

Downstream traffic, the direction toward the user, bit rates can be as much as 400 megabits

per second for business connections, and 100Mbit/s for residential service in some countries.

Upstream traffic, originating at the user, ranges from 384Kbit/s to more than 20Mbit/s. One

downstream channel can handle hundreds of cable modems. As the system grows, the cable

modem termination system (CMTS) can be upgraded with more downstream and upstream

ports, and grouped into CMTS hubs for efficient management.

Most Data Over Cable Service Interface Specification (DOCSIS) cable modems restrict

upload and download rates, with customizable limits. These limits are set in configuration

files which are downloaded to the modem using the Trivial File Transfer Protocol, when the

modem first establishes a connection to the provider's equipment.

In Cable Internet Access, like any other residential broadband technology, a population of

users share the available bandwidth. Some technologies share only their core network, while

some including Cable Internet and PON also share the access network. This arrangement

allows the network operator to take advantage of statistical multiplexing, a bandwidth sharing

technique which is employed to distribute bandwidth fairly, in order to provide an adequate

level of service at an acceptable price. However, the operator has to monitor usage patterns

and scale the network appropriately, to ensure that customers receive adequate service even

during peak-usage times. If the network operator does not provide enough bandwidth for a

particular neighbourhood, the service can become sluggish if many people are using the

service at the same time. Operators have been known to use a bandwidth cap, or other

bandwidth throttling technique. Users' download speed is limited during peak times, if they

have downloaded a large amount of data that day.

Different ways of Internet Access:

Dial-up connection: Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a dialed connection to an Internet service provider (ISP) via telephone lines. The user's computer or router uses an attached modem to encode and decode Internet Protocol packets and control information into and from analogue audio frequency signals, respectively.

ISDN: Integrated Services Digital Network (ISDN) is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the

traditional circuits of the public switched telephone network. The key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system.

DSL: Digital Subscriber Line (DSL) is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term Digital Subscriber Line is widely understood to mean Asymmetric Digital Subscriber Line (ADSL), the most commonly installed technical variety of DSL. DSL service is delivered simultaneously with regular telephone on the same telephone line. This is possible because DSL uses a higher frequency. These frequency bands are subsequently separated by filtering. The data throughput of consumer DSL services typically ranges from 256 Kb/s to 20 Mbit/s in the direction to the customer (downstream), depending on DSL technology, line conditions, and service-level implementation. In ADSL, the data throughput in the upstream direction, (i.e. in the direction to the service provider) is lower, hence the designation of asymmetric service. In Symmetric Digital Subscriber Line (SDSL) service, the downstream and upstream data rates are equal.

Cable TV Network: Cable Internet access is a form of broadband Internet access that uses the cable television infrastructure. This seminar report will cover this part in detail.

Wi-Fi: A Wi-Fi enabled device such as a personal computer, video game console, smartphone or digital audio player can connect to the Internet when within range of a wireless network connected to the Internet. The coverage of one or more (interconnected) access points — called hotspots — can comprise an area as small as a few rooms or as large as many square miles. Coverage in the larger area may depend on a group of access points with overlapping coverage. In addition to private use in homes and offices, Wi-Fi can provide public access at Wi-Fi hotspots provided either free-of-charge or to subscribers to various commercial services. Organizations and businesses - such as those running airports, hotels and restaurants - often provide free-use hotspots to attract or assist clients. Enthusiasts or authorities who wish to provide services or even to promote business in selected areas sometimes provide free Wi-Fi access. Routers that incorporate a digital subscriber line modem or a cable modem and a Wi-Fi access point, often set up in homes and other premises, can provide Internet access and internetworking to all devices connected (wirelessly or by cable) to them. With the emergence of MiFi and WiBro (a portable Wi-Fi router) people can easily create their own Wi-Fi hotspots that connect to Internet via cellular networks. Now many mobile phones can also create wireless connections via tethering on iPhone, Android, Symbian, and WinMo. One can also connect Wi-Fi devices in ad-hoc mode for client-to-client connections without a router. Wi-Fi also connects places that would traditionally not have network access, for example bathrooms, kitchens and garden sheds.

Wi-Max: WiMAX (Worldwide Interoperability for Microwave Access) is a telecommunications protocol that provides fixed and fully mobile Internet access. WiMAX is a standards-based technology enabling the delivery of last mile wireless broadband access as

an alternative to cable and DSL. The current WiMAX revision provides up to 40 Mbit/s with the IEEE 802.16m update expected to offer up to 1 Gbit/s fixed speeds.

GPRS and EDGE: General packet radio service (GPRS) is a packet oriented mobile data service on the 2G and 3G cellular communication systems global system for mobile communications (GSM). GPRS networks evolved to EDGE networks with the introduction of 8PSK encoding. Enhanced Data rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE was deployed on GSM networks beginning in 2003.

3G: 3G or 3rd Generation is a generation of standards for mobile phones and mobile telecommunications services fulfilling specifications by the International Telecommunication Union. Application services include wide-area wireless voice telephone, mobile Internet access, video calls and mobile TV, all in a mobile environment. Compared to the older 2G and 2.5G standards, a 3G system must allow simultaneous use of speech and data services, and provide peak data rates of at least 200 kbit/s according to the IMT-2000 specification. Recent 3G releases, often denoted 3.5G and 3.75G, also provide mobile broadband access of several Mbit/s to laptop computers and smartphones.

Leased Line: A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent (hence the term lease).

Fibre to the premises: Fibre to the premises is a form of fibre-optic communication delivery in which an optical fibre is run from the central office all the way to the premises occupied by the subscriber.

Satellite: Satellite Internet access is Internet access provided through satellites. The service can be provided to users world-wide through Low Earth Orbit (LEO) satellites. Geostationary satellites can offer higher data speeds, but their signals can not reach some polar regions of the world. Different types of satellite systems have a wide range of different features and technical limitations, which can greatly affect their usefulness and performance in specific applications.

Cable TV Network:

Cable TV Network is made up of coaxial cable lines that bring television signals to TV. Each television channel is given a 6-megahertz channel on the cable. Cable TV Networks are high bandwidth networks i.e. 550 to 750 MHz by their very nature of design. These networks were traditionally built as one way networks carrying 60-100 Cable TV channels downstream i.e. from Headend to the Subscriber.

Working of Cable Internet:

The television and the Internet transmission take place simultaneously on the same cable but at different frequencies. This allows the user to view TV and access Internet at the same time

When a cable company offers Internet access over the cable, Internet information can use the same cables because the cable modem system puts downstream data (data sent from the Internet to an individual computer) into a 6-MHz channel. On the cable, the data looks just like a TV channel. So Internet downstream data takes up the same amount of cable space as any single channel of programming.

One downstream channel can handle hundreds of cable modems. Upstream data (information sent from an individual back to the Internet) requires even less of the cable's bandwidth, just 2 MHz, since the assumption is that most people download far more information than they upload.

Hence setting up of a robust two-way Cable TV network is the first requisite before deploying Cable Modems on a Cable TV network. This is done by upgrades to the amplifiers in the cable distribution network etc.

Cable Network

Subscriber End

Equipments Required:

Putting both upstream and downstream data on the cable television system requires two types of equipment:

1. A cable modem at the customer end2. A cable modem termination system (CMTS) at the cable provider's end

Cable Modem:

For Cable Internet access on PC, a Cable Modem is required at user’s end. A cable modem is an external device that connects to the computer to provide high-speed data access via cable

TV networks. It has two connections; one to the TV cable wire and the other to a computer. A Cable Modem sends and receives data to and from the Internet by using the existing coaxial cable network.

The modem translates cable signals the same way a telephone modem translates signals from a telephone line. Cable modems translate radio frequency (RF) signals to and from the cable plant into Internet Protocol (IP), the communications protocol spoken by all computers connected to the Internet. At the customer premise, a high quality two way splitter is installed on the Cable TV line, with one output connected to the Cable Modem and the second output connected to the TV.

Tuner: The tuner will contain a diplexer, which allows the tuner to make use of one set of frequencies (generally between 42 and 850 MHz) for downstream traffic, and another set of frequencies (between 5 and 42 MHz) for the upstream data.

Demodulator: The most common demodulators have four functions.

A Quadrature Amplitude Modulation (QAM) demodulator takes a radio-frequency signal that has had information encoded in it by varying both the amplitude and phase of the wave, and turns it into a simple signal that can be processed by the analog-to-digital (A/D) converter.

The A/D converter takes the signal, which varies in voltage, and turns it into a series of digital 1s and 0s.

An Error correction module then checks the received information against a known standard, so that problems in transmission can be found and fixed.

MPEG Synchroniser: The network frames, or groups of data, are in MPEG format, so an MPEG synchronizer is used to make sure the data groups stay in line and in order.

Modulator: In cable modems that use the cable system for upstream traffic, a modulator is used to convert the digital computer network data into radio-frequency signals for transmission. It consists of:

1. A section to insert information used for error correction on the receiving end.2. A QAM modulator .3. A digital-to-analog (D/A) converter

MAC: The MAC sits between the upstream and downstream portions of the cable modem, and acts as the interface between the hardware and software portions of the various network protocols. All computer network devices have MACs.

 CPU: In the case of a cable modem the tasks are more complex than those of a normal network interface card. For this reason, in most cases, some of the MAC functions will be assigned to central processing unit (CPU).

Cable Modem Terminating System:

The Internet signals are in the digital domain and these need to be interfaced to the Analog Cable TV Network. This interface is termed Cable Modem Termination System (CMTS) and typically serves 2000 – 3000 Cable Modems and is connected to a high-speed data link. A typical CMTS consists of an Input interface, Router, Cable Modem card and a powerful Microprocessor. At the cable provider's head-end, the CMTS provides many of the same functions provided by the DSLAM in a DSL system.

The CMTS takes the traffic coming in from a group of customers on a single channel and routes it to an Internet service provider (ISP) for connection to the Internet. At the head-end, the cable providers will have, or lease space for a third-party ISP to have, servers for accounting and logging, Dynamic Host Configuration Protocol (DHCP) for assigning and administering the IP addresses of all the cable system's users. The downstream information flows to all connected users, just like in an Ethernet network -- it's up to the individual network connection to decide whether a particular block of data is intended for it or not.

On the upstream side, information is sent from the user to the CMTS -- other users don't see that data at all. The narrower upstream bandwidth is divided into slices of time, measured in milliseconds, in which users can transmit one "burst" at a time to the Internet. The division by time works well for the very short commands, queries and addresses that form the bulk of most users' traffic back to the Internet. A CMTS will enable as many as 1,000 users to connect to the Internet through a single 6-MHz channel. Since a single channel is capable of

30 to 40 megabits per second (Mbps) of total throughput, this means that users may see far better performance than is available with standard dial-up modems. As the system grows, the CMTS can be upgraded with more downstream and upstream ports.

DSL vs Cable:

Speed (advantage - Cable): Cable boasts faster speed than DSL Internet in theory. However, cable does not always deliver on the promise in everyday practical use.

Popularity (advantage - Both): In the US, cable Internet enjoys significantly greater popularity than DSL, although DSL has been closing the gap recently. Outside the US, DSL continues to hold the edge.

Customer Satisfaction (advantage - DSL): US cable services generally rate lower than DSL in customer surveys.

Security (advantage - Both): Cable and DSL implement different network security models. Historically, more concerns have existed with cable security, although cable providers have definitely taken steps to improve security over the past few years. It's likely both DSL and cable are "secure enough" for most people's needs.

Advantages of Cable Internet:

1. High connection speed2. Convenient – you are always connected to the internet3. Does not affect your phone line. You don’t need to switch your local phone service

provider.4. Unlike ADSL, its performance doesn't depend on distance from the central cable

office.

Disadvantages of Cable Intenet:

1. Bandwidth is shared over the same cable line. Connection speed is affected by the number of people using the internet at the same time in your neighborhood.

2. Higher security risk than dialup (personal firewall is needed).3. Not available to all cable TV networks.4. Usually tied with cable TV subscription.

Conclusion:

Cable Internet access is the principal competitor to DSL and is offered at a range of prices and speeds overlapping that of DSL.

Cable TV has a strong reach to the homes and therefore offering the Internet through cable is a scope for furthering the growth of internet usage in the homes.

The cable is an alternative medium for delivering the Internet Services in the US, there are millions of homes with cable modems, enabling the high-speed internet access over cable.

References:

http://en.wikipedia.org/wiki/Cable_Internet_access

http://en.wikipedia.org/wiki/Cable_modem

http://en.wikipedia.org/wiki/Internet_Access

http://en.wikipedia.org/wiki/Cable_modem_termination_system

http://computer.howstuffworks.com/cable-modem.htm

http://www.hathway.com/brodband/prod_broadband_faq3.asp