Broadband Internet access
The term broadband Internet access, often shortened to "broadband Internet" or just "broadband", generically refers to last-mile Internet connections exceeding the bandwidth capabilities of standard analog modems and of ISDN connections. Broadband Internet connections are typically capable of transmitting 512 kilobits per second (kbit/s) or more.
Broadband is also commonly known as high-speed Internet, because the increased bandwidth effectively reduces the time required for transmission of data; this term is something of a misnomer, however, since the actual transmission speed is essentially the same. An Internet access line can be compared to a water pipe: modem access over a telephone line is a small pipe with relatively low water capacity, while broadband access is a larger pipe with a comparatively larger water capacity. The water, or data, travels at roughly the same speed through either pipe, but the larger pipe can move more water, or data, in a given time period.
In some countries broadband services operate at over 1 Mbit/s for connections to private residences, with higher data transfer rates possible for business purposes, but involving a correspondingly higher charge.
In the United Kingdom many domestic users have connections either via cable modems, or via ADSL, and these typically run at around 500 kbit/s. Commercial users can obtain higher data rates for a higher subscription. In a few of the many areas not served by cable or ADSL, community organisations have begun to install Wi-Fi networks.
In the USA many users have connections at about 380 kbit/s (as of 2002), though this situation may change as new equipment appears.
Other technologies include bi-directional satellite satmodems and power line communication modems which use the electric grid to provide access to the Internet.
The typical broadband connection to date, whether cable or xDSL, is configured by the ISP to run at bit rates from 350-500 kbit/s. The full rate connection for a typical cable plant might be as high as 10 Mbit/s and with ADSL it might be 2 to 6 Mbit/s (limited by how long the subscriber loop is - shorter loop, higher speed).
In Canada, broadband Internet access is estimated to serve at least 53% of internet users (January 2003). The competition between the major broadband Internet providers in that country has recently caused frequent increases in the available bandwidth provided to home users. As of May 2004, a standard broadband Internet package provides 3.0Mbit/s downstream and 300kbit/s upstream rates for both cable- and DSL-based services. Some residential service providers (such as Cogeco or Rogers) offer speeds of 5Mbit/s or higher.
In practice, even this bandwidth is not always reliably available to the consumer, as ISPs tend to overbook their backbone capacity. Since most user connections typically only operate at a small fraction of their full rated bandwidth, this aggregation strategy works more often than not, so users can typically burst to their full bandwidth most of the time. Peer-to-peer file sharing systems stress these assumptions, and can cause major problems for ISPs who have excessively overbooked their capacity. (See network traffic engineering for a fuller discussion).
As takeup for this introductory products increases, telcos are starting to offer higher bit rate services. For existing connections, this most of the time simply involves reconfiguring the existing equipment at each end of the connection.
Newer technologies for twisted pair phone lines such as VDSL and pushing fiber optic connections closer to the subscriber in both telephone and cable plants are opening up the possibility of higher performance for streaming data, such as audio and video streams. There are now many streaming audio services, and several streaming video services. Broadband Internet access also facilitates the use of file sharing software.
The data rates on most broadband services still do not suffice to provide good quality video, as MPEG-2 quality video requires about 6 Mbit/s for good results. Adequate video for some purposes becomes possible at lower data rates, with rates of 768 kbit/s and 384 kbit/s used for some video conferencing applications. The MPEG-4 format delivers high-quality video at 2 Mbit/s, at the high end of cable modem and ADSL performance. The Ogg Tarkin format is intended to deliver similar performance.
As the bandwidth delivered to end-users increases, the market expects that video on demand services streamed over the Internet will become more popular, though at the present time such services generally require specialised networks.
Increased bandwidth has already made an impact on newsgroups: postings to groups such as alt.binaries.* have grown from JPEG images to entire CD and DVD images. According to NTL, the level of traffic on their network increased from a daily inbound news feed of 150 Gigabytes of data per day and 1 Terabyte of data out each day in 2001 to 500 Gigabytes of data inbound and over 4 Terabytes out each day in 2002.
Transmission rates for common broadband solutions:
| Connection | Transmission Speed |
|---|---|
| DS1 (Tier 1) | 1.544 Mbps |
| E1 | 2.048 Mbps |
| DS3 (Tier 3) | 44.736 Mbps |
| OC3 | 155.52 Mbps |
| OC12 | 622.08 Mbps |
| OC48 | 2.488 Gbps |
| OC192 | 9.953 Gbps |
| OC768 | 39.813 Gbps |
External links:
- Broadband Industry Structure PowerPoint presentation about broadband business models, technology and pricing.
- Broadband Fact Sheets Gives an overview of the different broadband connections available to consumers.