The main CRC building in Ottawa as seen|
through the lens of a special camera used
to determine a site's accessibility to wireless
communication. Photo courtesy of:
Communications Research Centre Canada
The View from CRCCommunication Research Centre scientist, Gérald Chouinard will provide insight into the technology behind broadband services in this regularly featured article. This month's topic addresses the question of "What is?" and "What is not?" Broadband Internet service.
What is Broadband?
The term broadband is generally used to describe high-speed Internet access. But just what exactly is it and how is it going to change your life?
To understand broadband, we have to first look at the characteristics of Internet access through the traditional telephone modem. Some of you may remember the old 300-baud (roughly 300 bits per second) phone connections, which later increased to 1,200, and eventually to 9,600 bauds. At that point, the data transfer on the phone line was so fast that no one could keep track of the text scrolling up on the alphanumeric display of the local terminal. After a time came more demanding software applications and modems that functioned at 14.4 kilobits-per-second (kbit/s), and then at 28.8 kbit/s, 33.6 kbit/s, and finally 56 kbit/s. The latter represents the practical limit in bit rate that a telephone voice channel can carry because it is encoded digitally at 64 kbit/s to be carried over the Public Switched Telephone Network. Some headroom is needed at the phone network's central office to filter and recover the data from the analog waveform generated by the non-synchronized 56 kbit/s stream at the subscriber modem.
Broadband: proposed definitions
Broadband has different meanings depending on the context. According to the International Telecommunications Union, broadband means 1.544 kbit/s (T1 speed) and beyond, in both forward and return directions. The National Broadband Task Force described broadband in its June 2001 report as: "… a high-capacity, two-way link between end user and access network suppliers capable of supporting full-motion interactive video applications delivered to all Canadians on terms comparable to those available in urban markets. A minimum symmetrical speed of 1.5 megabits per second per individual user is currently required to support these applications." The U.S. Federal Communication Commission defined broadband as 200 kbit/s and above in both directions.
Broadband: The Current Reality
The current commercial reality seems to be that an adequate high-speed Internet connection for small and medium-sized enterprises, and individual subscribers, ranges from 400 kbit/s to 3 Mbit/s in the forward direction, and between 128 and 640 kbit/s for the return. Depending on the location, these levels of access capacity can be obtained through cable modem, asymmetrical digital subscriber line (ADSL), satellite or terrestrial wireless.
Besides its actual higher data capacity, another key feature of broadband access is its "always-on" capability, as opposed to needing a phone modem to dial a connection.
The fact that high-speed access doesn't tie up your phone line is also a plus.
Hydro towers carry not only electricity|
but also fibre optic strands used to
communicate with the utility's control
systems. Excess fibre capacity is often
sold to third parties making hydro
companies an alternative bandwidth
supplier. Photo courtesy of:
Based on today's technology and applications, high-speed broadband typically includes services such as Web browsing, streaming video and audio, file transfers, and other lower-capacity services such as e-mails and newsgroups. These services generally require higher capacity for moving data from suppliers to subscribers than they do in the return direction.
The National Broadband Task Force concluded that with the rise in use of bi-directional communications such as peer-to-peer file exchange and videoconferencing, an equal amount of capacity or bandwidth will be needed between suppliers and subscribers to move data back and forth.
Peer-to-peer file-sharing developed very rapidly in the last few years, especially for audio files. However, things have become somewhat more leveled as a result of the Napster effect, which led to tighter enforcement of intellectual property laws. Video conferencing, on the other hand, is likely to continue to increase in use as people begin to discover the benefits of tele-learning, telehealth, etc. Video conferencing will likely define the highest capacity requirement for broadband access as it evolves toward better quality and full motion, resulting in the need for higher bandwidth.
Meanwhile, some network access suppliers have started asking for additional fees from subscribers who use unusually large amounts of bandwidth to cover for the over-dimensioning of the data network as compared to what is needed for a more casual level of Internet access. However, as more cost-effective technologies make their way to market, we could see a drop in access costs even if the typical Internet access use is likely to increase in time.
Broadband: An Evolving Definition
The National Broadband Task Force concluded in its June 2001 report that the definitions of "broadband services," "broadband networks" and related concepts should be dynamic and should encompass and reflect changes in technology, applications and the needs of individuals. They should also stress the potential of broadband to yield great economic and social benefits for Canadians.
For these reasons, the definition of broadband is still evolving. As the public becomes more aware of the capabilities and benefits of accessing data networks, the definition of broadband will continue to change. Data transmission capacity will also evolve as applications become more varied and sophisticated. The access networks will need to adapt to more demanding requirements. These networks will also need to move beyond the status quo and offer better quality and security for users.
Gérald Chouinard is the Program Manager of Communications Research Centre Canada's Rural and Remote Broadband Access (RRBA) Program (www.crc.ca/broadband).