1. Seminar by Ankur Desai Anisha Nayak Anish Kumar Department of Electronics and Communication Engineering, Gogte Institute of Technology

2. Contents 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

3. Different ways of Internet Access Dial-up connection ISDN DSL (ADSL and SDSL) Cable TV Network Wireless Network (Wimax, Wifi, EVDO, HSDPA and UMTS) T1 and T3 lines Optical Fibre line Satellite

5. 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.

6. Working of Cable Internet Internet over cable is a technology and service that uses the existing cable TV networks to bring Internet data to PC at a very high speed. Instead of getting an Internet connection through your telephone wire, you get a connection through your cable network (the same place your cable TV Connection comes from). Internet delivery over Cable TV requires a two-way network since information of selected website, etc. has to be transmitted to the Headend, from where it would be directed to the website of interest. Higher frequencies flow toward the subscriber and the lower frequencies go in the other direction.

7. 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

8. Working of Cable Internet 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

9. Working of Cable Internet 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.

10. Cable Network

11. 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 end 2. A cable modem termination system (CMTS) at the cable provider's end

12. 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.

13. Cable Modem 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.

14. Cable Modem 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.

15. Cable Modem 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.

16. Cable Modem 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).

17. 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.

18. Cable Modem Terminating 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.

19. Cable Modem Terminating System 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.

20. 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.

21. Advantages of Cable Internet High connection speed Convenient – you are always connected to the internet Does not affect your phone line. You don’t need to switch your local phone service provider. Unlike ADSL, its performance doesn't depend on distance from the central cable office.

22. Disadvantages of Cable Intenet 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. Higher security risk than dialup (personal firewall is needed). Not available to all cable TV networks. Usually tied with cable TV subscription.

23. 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 be 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.

24. 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_terminati on_system http://computer.howstuffworks.com/cable- modem.htm http://www.hathway.com/brodband/prod_broadband _faq3.asp

25. Thank you