April 2000

How Fast Can You Go?

With the popularity of the Internet today the question is not whether you use it, but the speed at which you connect. The most popular connection speeds available at home and office can be broken down into two separate categories, analog (modem) and digital (high-speed broadband).

Analog Modems

Analog modems utilize the "plain old telephone" (POTS) lines provided by the phone company. No special equipment is required to connect a modem to today's telephone networks, and the only requirement is that each end of the call must have a compatible modem. Analog modems allow digital data to flow over the telephone company's analog network by performing a digital-to-analog conversion for transmission onto the network and an analog-to-digital conversion on the receiving end.

Analog modem connections are the standard, but they are limited by the telephone company's voice bandwidth service. Current analog modems are struggling to achieve rates of only 56 Kbps. With a bandwidth of only about 3,000 Hz, there is an extremely small finite limit on the amount of data that can be encoded and sent reliably through this network. With the popularity of the Internet and the amount of information on the simplest of web pages, user requirements far outpace the capacity of analog modems.

Digital Connections

Integrated services digital network (ISDN) is a telephone company technology that provides digital service, typically in increments of 64 Kbps channels. ISDN has been around for many years, but its popularity is only now beginning to increase due to analog modem limitations and an increase in Internet usage. The telephone company must install services within its phone switches to support this digitally switched connection service. Roll-out of ISDN got off to a slow start and was stalled by high costs, lack of standards, and low consumer acceptance rates.

Digital subscriber lines (DSL) has two main categories, asymmetric digital subscriber line (ADSL) and symmetric digital subscriber line (SDSL), but the technology is usually called xDSL when referring to all of the different types. This technology, backed by telephone companies, provides the next level of bandwidth services to homes and businesses using the existing telephone cabling infrastructure. Home DSL, provided through current POTS lines, has a bandwidth speed of up to 9 Mbps, but distance and line quality can reduce what is achievable. DSL technologies will utilize a greater range of frequencies than traditional telephone services, allowing for greater bandwidth with which to send and receive information. This technology is still in the early stages of roll-out, with standards and products just getting under way.

Cable modems are devices that attach to the home cable TV network connection. This broadband technology, driven by cable companies, would provide services beyond traditional broadcast cable TV, such as Internet access. Along with xDSL, cable modems are still in the early stages of development. The industry faces a number of challenges, including return path capabilities and standards. However, potential bandwidth estimates range upwards of 30 Mbps from service provider to subscriber.

Cable networks are inherently different in design than telephone networks. Cable networks are broadcast oriented, with each subscriber in an area receiving the same signals as all others in that area. xDSL is circuit oriented so that each connection is independent of all others. Cable networks are inherently hierarchical in nature and thus require two paths: downstream and upstream. This requires either a second cable plant for upstream or a second frequency band allocated onto the existing system.

A T-1 connection is one of the most popular for businesses to use in order to access the Internet. A T-1 line actually consists of 24 individual channels, each of which supports transfer of 64 Kbps. A dedicated T-1 connection can support data rates of 1.544 Mbps. One of the new uses for T-1 connection is to carry both data and voice transmissions over a single connection. Each 64 Kbps channel can be configured to carry voice or data traffic.

Finally, the T-3 connection is the backbone of the Internet itself. You can think of a T-3 as a T-1 on steroids. Instead of the T-1's 24 channels per line with a transfer speed of 1.54 Mbps, a T-3 can support 672 channels per line with a transfer speed of 43 Mbps.

As you can see, there are many choices when it comes to picking an Internet connection type. If you spend as much time on your computer as I do, the faster choice is the better. Personally, I have a cable modem at home and the NYSSCPA offices use a full T-1 connection for both voice and data. Needless to say, I am spoiled and I could not image using a 56 K modem.

Ask yourself the following three questions when deciding what type of connection is best for you:

* Is the connection type you want available in your area?
* How much do you want to spend per month?
* How much time do you spend on the Internet?

In other words, decide whether the benefits outweigh the cost.

For more information, please contact NYSSCPA Chief Technology Officer Kevin Lewis at (212) 719-8340, (800) 633-6320, or klewis@nysscpa.org. *