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About Bandwidth
Bandwidth, or capacity, refers to the amount of data a given technology or infrastructure can transmit over time. It is usually expressed in kilobits per second (Kbps) or megabits per second (Mbps).
There is often confusion about bandwidth due to the difference between kilobytes and kilobits. Bits are used to talk about data transfer rates (1 kilobit = 1000 bits), while bytes are used to talk about storage size calculations (1 kilobyte = 1024 bytes). There are 8 bits in a byte. So a 28.8 Kbps (kilobits per second) modem can actually only handle a maximum of 3.6 KB/s (kilobytes per second) of data, including the connection to the ISP, the data holding the TCP/IP packets together, and other essential information. Given all these facts together, your download speeds will often be slower than the "potential" advertised.
Internet Connection Speed Comparison Chart
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Dial-up
Access On demand access using a modem and regular telephone line (POT). 2400 bps to 56 Kbps Twisted pair (regular phone lines) Cheap but slow compared with other technologies. Speed may degrade due to the amount of line noise
ISDN
Dedicated telephone line and router required. 64 Kbps to 128 Kbps Twisted pair Not available everywhere but becoming more widespread. An ISDN line costs slightly more than a regular telephone line, but you get 2 phone lines from it. 56K ISDN is much faster than a 56K dialup line
Cable
Special cable modem and cable line required. 512 Kbps to 20 Mbps Coaxial cable; in some cases telephone lines used for upstream requests. Must have existing cable access in area. Cost of bring service into an area and trenching cable can be prohibitive.
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ADSL/DSL
Asymmetric Digital Subscriber Line
This new technology uses the unused digital portion of a regular copper telephone line to transmit and receive information. ADSL is asymmetric since it recieves at 6 to 8 Mbps per second but can only send data at 64 Kbps. A special modem and adapter card are required. 128 Kbps to 8 Mbps Twisted pair (used as a digital, broadband medium) Doesn’t interfere with normal telephone use. Bandwidth is dedicated, not shared as with cable. Bandwidth is affected by the distance from the network hubs. Must be within 5 km (3.1 miles) of telephone company switch.
Wireless
Wireless (LMCS) Access is gained by connection to a high speed cellular like local multi-point communications system (LMCS) network via wireless transmitter/receiver. 30 Mbps or more Airwaves Requires outside antenna. Can be used for high speed data, broadcast TV and wireless telephone service.
Broadband over Power
Uses existing electrical infrastructure to deliver broadband speeds using BPL "modems" 500Kbps to 3Mbps Ordinary power lines Still an emerging technology, not widely available Significantly lower deployment costs than comparable technologies like DSL/Cable.
Satellite
Newer versions have two-way satellite access, removing need for phone line. In older versions, the computer sends request for information to an ISP via normal phone dial-up communications and data is returned via high speed satellite to rooftop dish, which relays it to the computer via a decoder box. 6 Mbps or more Airwaves Requires outside antenna. Bandwidth is not shared. Satellite companies are set to join the fray soon which could lead to integrated TV and Internet service using the same equipment and WebTV like integrated services. Latency is typically high. Some connections require an existing Internet service account. Setup fees can range from $500-$1000.
Frame Relay
Provides a type of "party line" connection to the Internet. Requires a FRAD (Frame Relay Access Device) similar to a modem, or a DSU/CSU. 56 Kbps to 1.544 Mbps (or more, depending on connection type) Various May cost less than ISDN in some locations.
Fractional T1
Only a portion of the 23 channels available in a T1 line is actually used. 64 Kbps to 1.544 Mbps Twisted-pair or coaxial cable Cheaper than a full T1 line with growth options of 56 Kbps or 64 Kbps increments as required. T1 Special lines and equipment (DSU/CSU and router) required. 1.544 Mbps Twisted-pair, coaxial cable, or optical fiber Typically used for high bandwidth demands such as videoconferencing and heavy graphic file transfers. Minimum for large businesses and ISPs.
T3
Typically used for ISP to Internet infrastructure. 44.736 Mbps Optical fiber.
OC-1
Typically used for ISP to Internet infrastructure within Internet infrastructure. 51.84 Mbps Optical fiber.
OC-3
Typically used for large company backbone or Internet backbone. 155.52 Mbps Optical fiber
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