Broadband
Internet access, often shortened to just "broadband", is
high-speed Internet access-typically contrasted with
dial-up access over a modem.
Dial-up modems are generally only capable of a maximum
bitrate of 56 kbit/s (kilobits per second) and require
the full use of a telephone line-whereas broadband
technologies supply at least double this speed and
generally without disrupting telephone use.
Although various minimum speeds have been used in
definitions of broadband, ranging up from 64 kbit/s up
to 1.0 Mbit/s, the OECD report is typical in counting
only download speeds equal to or faster than 256 kbit/s
as broadband, and the US FCC use 200 kbit/s in their
definition.
Speeds are defined in terms of maximum download because
several common consumer broadband technologies such as
ADSL are "asymmetric"—supporting much slower maximum
upload speeds than download.
"Broadband penetration" is now treated as a key economic
indicator.
Broadband is
often called high-speed Internet, because it usually has
a high rate of data transmission. In general, any
connection to the customer of 256 kbit/s (0.256 Mbit/s)
or more is considered broadband Internet. The
International Telecommunication Union Standardization
Sector (ITU-T) recommendation I.113 has defined
broadband as a transmission capacity that is faster than
primary rate ISDN, at 1.5 to 2 Mbit/s. The FCC
definition of broadband is 200 kbit/s (0.2 Mbit/s) in
one direction, and advanced broadband is at least 200
kbit/s in both directions. The Organization for Economic
Co-operation and Development (OECD) has defined
broadband as 256 kbit/s in at least one direction and
this bit rate is the most common baseline that is
marketed as "broadband" around the world. There is no
specific bitrate defined by the industry, however, and
"broadband" can mean lower-bitrate transmission methods.
Some Internet Service Providers (ISPs) use this to their
advantage in marketing lower-bitrate connections as
broadband.
In practice, the advertised bandwidth is not always
reliably available to the customer; ISPs often allow a
greater number of subscribers than their backbone
connection can handle, under the assumption that most
users will not be using their full connection capacity
very frequently. This aggregation strategy works more
often than not, so users can typically burst to their
full bandwidth most of the time; however, peer-to-peer
(P2P) file sharing systems, often requiring extended
durations of high bandwidth, stress these assumptions,
and can cause major problems for ISPs who have
excessively overbooked their capacity. For more on this
topic, see traffic shaping. As takeup for these
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.
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
specialized networks. The data rates on most broadband
services still do not suffice to provide good quality
video, as MPEG-2 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, and rates as low as 100 kbit/s used for
videophones using H.264/MPEG-4 AVC. The MPEG-4 format
delivers high-quality video at 2 Mbit/s, at the high end
of cable modem and ADSL performance.
Increased bandwidth has already made an impact on
newsgroups: postings to groups such as alt.binaries.*
have grown from JPEG files 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.
The
standard broadband technologies in most areas are DSL
and cable modems. Newer technologies in use include VDSL
and pushing optical fiber connections closer to the
subscriber in both telephone and cable plants.
Fiber-optic communication, while only recently being
used in fiber to the premises and fiber to the curb
schemes, has played a crucial role in enabling Broadband
Internet access by making transmission of information
over larger distances much more cost-effective than
copper wire technology. In a few areas not served by
cable or ADSL, community organizations have begun to
install Wi-Fi networks, and in some cities and towns
local governments are installing municipal Wi-Fi
networks. As of 2006, high speed mobile Internet access
has become available at the consumer level in some
countries, using the HSDPA and EV-DO technologies. The
newest technology being deployed for mobile and
stationary broadband access is WiMAX.
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