ADSL, cable modems and the need for speed

Two remote access technologies which offer far greater speeds than ISDN or 56Kbit/s modems are ADSL (asynchronous digital subscriber line) and cable modems. Both are still some way in the future, with only a handful of New Zealand companies trialling services based on either technology. Like ISDN, ADSL works over regular phone lines. Theoretically, ADSL adapters can download data at up to 9Mbit/s, although initial services will top out at 1.5Mbit/s and uploads can be 10 times slower than downloads.

Two remote access technologies which offer far greater speeds than ISDN or 56Kbit/s modems are ADSL (asynchronous digital subscriber line) and cable modems.

Both are still some way in the future, with only a handful of New Zealand companies trialling services based on either technology.

Like ISDN, ADSL works over regular phone lines. Theoretically, ADSL adapters can download data at up to 9Mbit/s, although initial services will top out at 1.5Mbit/s and uploads can be 10 times slower than downloads.

The cable companies are also jumping into the bandwidth fray. Using the same cable wiring that carries their television services, cable companies will provide a faster, less expensive alternative to ADSL, with possible download speeds of up to 30Mbit/sec — more than twice as fast as ADSL. Uploads are also significantly slower. Unlike ADSL and ISDN, which provide a dedicated line from your PC to your ISP, the local cable system is shared among all users. So if everyone in the neighbourhood is Web surfing at the same time, everyone will take a bandwidth hit. Cable companies reserve a separate part of the line for television, so TV watchers won’t affect speeds.

In New Zealand, Telecom is trialling ADSL internally and has no set plans to launch an ADSL-based service. It is also conducting a cable modem pilot limited to Wellington staff members, which is being closely watched by Telecom subsidiaries Xtra and First Media.

Meanwhile, Petone-based cable company Saturn Communications is testing cable modems internally. The recent 35% buy-in of Canadian cable company SaskTel may indicate future ADSL plans. SaskTel is the first North American company to launch a commercial ADSL service in the Canadian province of Saskatchewan. The SaskTel trial, among about eight employees, lasted about six weeks before the company launched the service.

Last month SaskTel invested $30 million in Saturn in exchange for a 35% equity stake.

According to Gartner Group, over the next five years ADSL’s hold on the access market is expected to reach 5% of the total consumer market and 15% of the total business access market. At the same time, cable modems are expected to hold 15% and 5% of the total consumer and business markets, respectively.

By the time ADSL becomes a product that consumers can buy, it may be supplanted by a similar technology like rate adaptive DSL, which covers symmetric download and upload rates and even higher throughput.

Another issue is that ADSL currently operates only as a dedicated connection from your computer to an ADSL adapter that your ISP online service installs in the phone company’s central office. In other words, you won’t be able to make ADSL connections to anyone else over the public switched network, as you can with an ISDN line or an analogue modem.

Despite uncertainty, remote access vendors are working on products. Hayes, Motorola and 3Com all have ADSL products in the works. In March US Robotics announced an end-to-end cable modem system for providers that wish to offer Internet access over their cable TV networks and USR has created a cable access business division.

Clear Communications says it does not have any plans for either technology.

Meanwhile, the New Zealand Internet Group (IHUG) is trialling a satellite-based service which is due to go live in three months. The trial, which is limited to 500 users, offers Internet connections at around 1.5Mbit/s.

Join the newsletter!

Error: Please check your email address.
Show Comments
[]