Evolution Of High-Speed Services

Most residential and small business consumers currently receive Internet service from ISPs via traditional "dial-up" telephone services provided by local exchange carriers (LECs) over copper telephone lines. Customers purchase telephone services from LECs at standard tariffed prices and use such services to gain access to ISPs, and, through them, the Internet. This "last mile" transmission capability is available independently of the choice of ISP. In these dial-up arrangements, customers use modems with their computers that are connected to their telephone lines. Increasingly, customers are using the local telephone network to obtain high-speed access to the Internet through xDSL technologies provided by incumbent and competitive LECs. In fact, we found significant growth in advanced services provided to residential and small business customers by LECs between 1998 and 1999.

In recent years, industry investment in infrastructure to support high-speed services has increased dramatically, driven in part by the rapidly rising demand for such services. Service providers are deploying a variety of networks that rely on different network architectures and transmission paths, including copper wire, cable, terrestrial wireless radio spectrum, satellite radio spectrum, or a combination of these and other media, to provide high-speed services. In the coming years, analysts predict rapid growth in subscribership of high-speed services provided using each of these technologies.

In particular, a number of cable television operators, both incumbents and new entrants, have started offering access to the Internet over their cable plant. These services provide access with much higher transmission speeds than traditional dial-up services and are offered primarily to residential customers over the cable systems’ shared media hybrid fiber coaxial networks. The coaxial cable transmits signals to the cable modem, which, in turn, is connected to the computer. For the return path, some cable modem services require the customers’ computers to send signals upstream over traditional dial-up telephone connections. With more advanced cable modem networks, both directions of traffic are transmitted via the coaxial cable, which permits the connection to be open at all times and offer higher transmission speeds.

In general, ISPs receive communications from their customers’ computers and route the communications to other computers connected either to their networks or other networks. Some ISPs often combine their services with proprietary or non-proprietary content. In other words, they often compete as content providers as well as ISPs. Those ISPs that combine content with Internet service are sometimes referred to as online service providers (OSPs).

   What is a Cable Modem?

Cable modems are designed to operate over cable TV lines to provide high-speed access to the Web or corporate Intranets. A power splitter and a new cable are usually required. The splitter divides the signal for the "old" installations and the new segment that connects the cable modem. No television sets are accepted on the new string that goes to the cable modem.

   How do I get a Cable Modem?

You need to call your cable provider to find out if they provide Internet service in your area. Then you will either lease the modem from the cable provider or purchase the modem at retail. The availability of modems at retail will depend on the cable provider.

   What are the basic minimum requirements for a cable modem?

There is not really a minimum requirement as far as the cable modem is concerned. The installers from the cable operator may have some requirements set up based on what kind of applications and drivers they want to install for their system. Usually the installer will plug in an Ethernet card, and they want to be able to get that working easily. That's the main reason they require a reasonably new computer.

   How Does the Cable Modem Work?

This term "Cable Modem" refers to a network interface card that communicates with the cable network, sending and receiving data in two slightly different ways. In the downstream direction, the digital data is modulated and then placed on a typical 6 MHz television channel, somewhere between 50 MHz and 750MHz. Currently, 64 QAM (Quadrature Amplitude Modulation) is the preferred downstream modulation technique, offering up to 27 Mbps per 6 MHz channel. This signal can be placed in a 6 MHz channel adjacent to TV signals on either side without disturbing the cable television video signals.

In a two-way activated cable network, the upstream (also known as reverse path) is transmitted between 5 and 42 MHz. This tends to be a noisy environment with RF interface and impulse noise. Most cable companies use QPSK (Quadrature Phase Shift Keying) or a similar modulation scheme in the upstream direction, because QPSK is a more robust scheme than higher order modulation techniques in a noisy environment. The drawback is that QPSK is slower than QAM.

The transmitted signal from the cable modem, can be so strong that any TV sets connected on the same string might be disturbed. The isolation of the splitter may not be sufficient, so an extra high-pass filter can be needed in the string that goes to the TV-sets. The high-pass filter allows only the TV-channel frequencies to pass, and blocks the upstream frequency band. The other reason for the filter is to block ingress in the low upstream frequency range from the in-house wiring.

    What is the Difference between DSL vs. Cable Modem?

Cable modem services offer shared bandwidth between you and your neighbors. Your speed will vary with how many people are on the cable modem network, which may be a disadvantage. With DSL service, you have a dedicated connection to your home.

    What are the Advantages to having Cable Modem?

Faster: Cable Modems are much faster than analog modems. Cable modem speeds vary, depending on the cable modem setup, cable company architecture, and traffic load. You should expect anywhere between 500-1000kBit/sec when downloading files from the Internet. Most of the time, this limit is just based on the speed of the Internet overall. The ‘advertised’ speed is usually based on the maximum throughput achievable by the modem itself. But there are many other factors affecting your speed.
Uploading speeds (the speed at which you are sending data) is usually quite a bit less. Count on 128 kBit/sec to 500 kBit/sec. Again, this will vary based on the configuration of your local system. Most Cable Modems can be remotely configured to limit upload and download speeds, all that depend on the number of users and amount of bandwidth that shared by those users.

Always on: Your Cable Modem connection is always there. There’s no need to dial up and listen to your modem squawk. And there’s no frustration about the line dropping.

Flat Rate Service: Cable Modem typically don’t have usage-sensitive pricing, which means that the connection can be used any time for as long as you need without incurring usage charges. Technical advances enable prices to fall and gain in power, facilitating the creation and operation of global networks.