Broadband Internet access, often shortened to just broadband, is a high data rate Internet access—typically contrasted with dial-up access using a 56k modem.
Dial-up modems are limited to a bitrate of less than 56 kbit/s (kilobits per second) and require the dedicated use of a telephone line—whereas broadband technologies supply more than double this rate and generally without disrupting telephone use.
Although various minimum bandwidths have been used in definitions of broadband, ranging up from 64 kbit/s up to 4.0 Mbit/s[1], the 2006 OECD report[2] is typical by defining broadband as having download data transfer rates equal to or faster than 256 kbit/s, while the United States (US) Federal Communications Commission (FCC) as of 2010, defines "Basic Broadband" as data transmission speeds of at least 4 megabits per second (Mbps), or 4,000,000 bits per second, downstream (from the Internet to the user’s computer) and 1 Mbps upstream (from the user’s computer to the Internet).[3] The trend is to raise the threshold of the broadband definition as the marketplace rolls out faster services.[4]
Data rates are defined in terms of maximum download because several common consumer broadband technologies such as ADSL are "asymmetric"—supporting much slower maximum upload data rate than download.
"Broadband penetration" is now treated as a key economic indicator.[2][5]
Contents |
Broadband is often called "high-speed" access to the 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 greater is more concisely considered broadband Internet access. 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 4.0 Mbit/s. 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 (Internet Service Providers) often allow a greater number of subscribers than their backbone connection or neighborhood access network 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 usage, 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 low 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 ADSL and cable internet. 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, broadband 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.
Roughly double the dial-up rate can be achieved with multilinking technology. What is required are two modems, two phone lines, two dial-up accounts, and ISP support for multilinking, or special software at the user end. This inverse multiplexing option was popular with some high-end users before ISDN, DSL and other technologies became available.
Diamond and other vendors had created dual phone line modems with bonding capability. The data rate of dual line modems is faster than 90 kbit/s. The Internet and phone charge will be twice the ordinary dial-up charge.
Load balancing takes two Internet connections and feeds them into your network as one double data rate, more resilient Internet connection. By choosing two independent Internet providers the load balancing hardware will automatically use the line with least load which means should one line fail, the second one automatically takes up the slack.
Integrated Service Digital Network (ISDN) is one of the oldest broadband digital access methods for consumers and businesses to connect to the Internet. It is a telephone data service standard. Its use in the United States peaked in the late 1990s prior to the availability of DSL and cable modem technologies. Broadband service is usually compared to ISDN-BRI because this was the standard broadband access technology that formed a baseline for the challenges faced by the early broadband providers. These providers sought to compete against ISDN by offering faster and cheaper services to consumers.
A basic rate ISDN line (known as ISDN-BRI) is an ISDN line with 2 data "bearer" channels (DS0 - 64 kbit/s each). Using ISDN terminal adapters (erroneously called modems), it is possible to bond together 2 or more separate ISDN-BRI lines to reach bandwidths of 256 kbit/s or more. The ISDN channel bonding technology has been used for video conference applications and broadband data transmission.
Primary rate ISDN, known as ISDN-PRI, is an ISDN line with 23 DS0 channels and total bandwidth of 1,544 kbit/s (US standard). ISDN E1 (European standard) line is an ISDN lines with 30 DS0 channels and total bandwidth of 2,048 kbit/s. Because ISDN is a telephone-based product, a lot of the terminology and physical aspects of the line are shared by the ISDN-PRI used for voice services. An ISDN line can therefore be "provisioned" for voice or data and many different options, depending on the equipment being used at any particular installation, and depending on the offerings of the telephone company's central office switch. Most ISDN-PRI's are used for telephone voice communication using large PBX systems, rather than for data. One obvious exception is that ISPs usually have ISDN-PRI's for handling ISDN data and modem calls.
It is mainly of historical interest that many of the earlier ISDN data lines used 56 kbit/s rather than 64 kbit/s "B" channels of data. This caused ISDN-BRI to be offered at both 128 kbit/s and 112 kbit/s rates, depending on the central office's switching equipment.
Advantages:
Disadvantages:
These are highly-regulated services traditionally intended for businesses, that are managed through Public Service Commissions (PSCs) in each state, must be fully defined in PSC tariff documents, and have management rules dating back to the early 1980s which still refer to teletypes as potential connection devices. As such, T-1 services have very strict and rigid service requirements which drive up the provider's maintenance costs and may require them to have a technician on standby 24 hours a day to repair the line if it malfunctions. (In comparison, ISDN and DSL are not regulated by the PSCs at all.) Due to the expensive and regulated nature of T-1 lines, they are normally installed under the provisions of a written agreement, the contract term being typically one to three years. However, there are usually few restrictions to an end-user's use of a T-1, uptime and bandwidth data rates may be guaranteed, quality of service may be supported, and blocks of static IP addresses are commonly included.
Since a T-1 was originally conceived for voice transmission, and voice T-1's are still widely used in businesses, it can be confusing to the uninitiated subscriber. It is often best to refer to the type of T-1 being considered, using the appropriate "data" or "voice" prefix to differentiate between the two. A voice T-1 would terminate at a phone company's central office (CO) for connection to the PSTN; a data T-1 terminates at a point of presence (POP) or data center. The T-1 line which is between a customer's premises and the POP or CO is called the local loop. The owner of the local loop need not be the owner of the network at the POP where your T-1 connects to the Internet, and so a T-1 subscriber may have contracts with these two organizations separately.
The nomenclature for a T-1 varies widely, cited in some circles a DS-1, a T1.5, a T1, or a DS1. Some of these try to distinguish amongst the different aspects of the line, considering the data standard a DS-1, and the physical structure of the trunk line a T-1 or T-1.5. They are also called leased lines, but that terminology is usually for data rates under 1.5 Mbit/s. At times, a T-1 can be included in the term "leased line" or excluded from it. Whatever it is called, it is inherently related to other broadband access methods, which include T-3, SONET OC-3, and other T-carrier and Optical Carriers. Additionally, a T-1 might be aggregated with more than one T-1, producing an nxT-1, such as 4xT-1 which has exactly 4 times the bandwidth of a T-1.
When a T-1 is installed, there are a number of choices to be made: in the carrier chosen, the location of the demarcation point, the type of channel service unit (CSU) or data service unit (DSU) used, the WAN IP router used, the types of bandwidths chosen, etc. Specialized WAN routers are used with T-1 lines that route Internet or VPN data onto the T-1 line from the subscriber's packet-based (TCP/IP) network using customer premises equipment (CPE). The CPE typical consists of a CSU/DSU that converts the DS-1 data stream of the T-1 to a TCP/IP packet data stream for use in the customer's Ethernet LAN. It is noteworthy that many T-1 providers optionally maintain and/or sell the CPE as part of the service contract, which can affect the demarcation point and the ownership of the router, CSU, or DSU.
Although a T-1 has a maximum of 1.544 Mbit/s, a fractional T-1 might be offered which only uses an integer multiple of 128 kbit/s for bandwidth. In this manner, a customer might only purchase 1/12th or 1/3 of a T-1, which would be 128 kbit/s and 512 kbit/s, respectively.
T-1 and fractional T-1 data lines are symmetric, meaning that their upload and download data rates are the same.
Where available, this method of broadband connection to the Internet would indicate that Internet access is very fast. However, just because Ethernet is offered doesn't mean that the full 10, 100, or 1000 Mbit/s connection can be utilized for direct Internet access. In a college dormitory, for example, the 100 Mbit/s Ethernet access might be fully available to on-campus networks, but Internet access bandwidths might be closer to 4xT-1 data rate (6 Mbit/s). If you are sharing a broadband connection with others in a building, the access bandwidth of the leased line into the building would of course govern the end-user's data rate.
In certain locations, however, true Ethernet broadband access might be available. This would most commonly be the case at a POP or a data center, and not at a typical residence or business. When Ethernet Internet access is offered, it could be fiber-optic or copper twisted pair, and the bandwidth will conform to standard Ethernet data rates of up to 10 Gbit/s. The primary advantage is that no special hardware is needed for Ethernet. Ethernet also has a very low latency.
One of the great challenges of broadband is to provide service to potential customers in areas of low population density, such as to farmers, ranchers, and small towns. In cities where the population density is high, it is easy for a service provider to recover equipment costs, but each rural customer may require expensive equipment to get connected.
Several rural broadband solutions exist, though each has its own pitfalls and limitations. Some choices are better than others, but are dependent on how proactive the local phone company is about upgrading their rural technology.
Wireless Internet Service Provider (WISPs) are rapidly becoming a popular broadband option for rural areas,. The technology's line-of-sight requirements may hamper connectivity in some areas with hilly and heavily foliated terrain. However, the Tegola project, a successful pilot in remote Scotland, demonstrates that wireless can be a viable option[6]. In addition, compared to hard-wired connectivity, there are security risks (unless robust security protocols are enabled); speeds are significantly slower (2 – 50 times slower); and the network can be less stable, due to interference from other wireless devices, weather and line-of-sight problems.[7]
Satellites in geostationary orbits are able to relay broadband data from the satellite company to each customer. Satellite Internet is usually among the most expensive ways of gaining broadband Internet access, but in rural areas it may be the only choice other than cellular broadband. However, costs have been coming down in recent years to the point that it is becoming more competitive with other broadband options.
Broadband satellite Internet also has a high latency problem is due to the signal having to travel to an altitude of 35,786 km (22,236 mi) above sea level (from the equator) out into space to a satellite in geostationary orbit and back to Earth again. The signal delay can be as much as 500 milliseconds to 900 milliseconds, which makes this service unsuitable for applications requiring real-time user input such as certain multiplayer Internet games and first-person shooters played over the connection. Despite this, it is still possible for many games to be played, but the scope is limited to real-time strategy or turn-based games. The functionality of live interactive access to a distant computer can also be subject to the problems caused by high latency. Additionally, some satellite Internet providers do not support VPN due to latency issues[8]. These problems are more than tolerable for just basic email access and web browsing and in most cases are barely noticeable.
For geostationary satellites there is no way to eliminate this problem. The delay is primarily due to the great distances travelled which, even at the speed of light (about 300,000 km/second or 186,000 miles per second), can be significant. Even if all other signalling delays could be eliminated it still takes electromagnetic radio waves about 500 milliseconds, or half a second, to travel from ground level to the satellite and back to the ground, a total of over 71,400 km (44,366 mi) to travel from the source to the destination, and over 143,000 km (88,856 mi) for a round trip (user to ISP, and then back to user—with zero network delays). Factoring in other normal delays from network sources gives a typical one-way connection latency of 500–700 ms from the user to the ISP, or about 1,000–1,400 milliseconds latency for the total Round Trip Time (RTT) back to the user. This is far worse than most dial-up modem users' experience, at typically only 150–200 ms total latency.
Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellites however do not have such great delays. The current LEO constellations of Globalstar and Iridium satellites have delays of less than 40 ms round trip, but their throughput is less than broadband at 64 kbps per channel. The Globalstar constellation orbits 1,420 km above the earth and Iridium orbits at 670 km altitude. The proposed O3b Networks MEO constellation scheduled for deployment in 2010 would orbit at 8,062 km, with RTT latency of approximately 125 ms. The proposed new network is also designed for much higher throughput with links well in excess of 1 Gbps (Giga bits per second).
Most satellite Internet providers also have a FAP (Fair Access Policy). Perhaps one of the largest disadvantages of satellite Internet, these FAPs usually throttle a user's throughput to dial-up data rates after a certain "invisible wall" is hit (usually around 200 MB a day). This FAP usually lasts for 24 hours after the wall is hit, and a user's throughput is restored to whatever tier they paid for. This makes bandwidth-intensive activities nearly impossible to complete in a reasonable amount of time (examples include P2P and newsgroup binary downloading).
The European ASTRA2Connect system has a FAP based on a monthly limit of 2Gbyte of data downloaded, with download data rates reduced for the remainder of the month if the limit is exceeded. Other Satellite Internet offers have advanced FAP mechanisms based on sliding time windows. It is the case for instance for the Tooway service that verifies download quotas during the last hours, days and weeks. The purpose is to allow temporary excessive downloads when needed while saving volume for the end of the month.[9].
Advantages
Disadvantages
Cellular phone towers are very widespread, and as cellular networks move to third generation (3G) networks they can support fast data; using technologies such as EVDO, HSDPA and UMTS.
These can give broadband access to the Internet, with a cell phone, with Cardbus, ExpressCard, or USB cellular modems, or with cellular broadband routers, which allow more than one computer to be connected to the Internet using one cellular connection.
This is a new service still in its infancy that may eventually permit broadband Internet data to travel down standard high-voltage power lines. However, the system has a number of complex issues, the primary one being that power lines are inherently a very noisy environment. Every time a device turns on or off, it introduces a pop or click into the line. Energy-saving devices often introduce noisy harmonics into the line. The system must be designed to deal with these natural signaling disruptions and work around them.
Broadband over power lines (BPL), also known as Power line communication, has developed faster in Europe than in the US due to a historical difference in power system design philosophies. Nearly all large power grids transmit power at high voltages in order to reduce transmission losses, then near the customer use step-down transformers to reduce the voltage. Since BPL signals cannot readily pass through transformers, repeaters must be attached to the transformers. In the US, it is common for a small transformer hung from a utility pole to service a single house. In Europe, it is more common for a somewhat larger transformer to service 10 or 100 houses. For delivering power to customers, this difference in design makes little difference, but it means delivering BPL over the power grid of a typical US city will require an order of magnitude more repeaters than would be required in a comparable European city.
The second major issue is signal strength and operating frequency. The system is expected to use frequencies in the 10 to 30 MHz range, which has been used for decades by licensed amateur radio operators, as well as international shortwave broadcasters and a variety of communications systems (military, aeronautical, etc.). Power lines are unshielded and will act as transmitters for the signals they carry, and have the potential to completely wipe out the usefulness of the 10 to 30 MHz range for shortwave communications purposes, as well as compromising the security of its users.
This typically employs the current low-cost 802.11 Wi-Fi radio systems to link up remote locations over great distances, but can use other higher-power radio communications systems as well.
Traditional 802.11b was licensed for omnidirectional service spanning only 100–150 meters (300–500 ft). By focusing the signal down to a narrow beam with a Yagi antenna it can instead operate reliably over a distance of many miles, although the technology's line-of-sight requirements hamper connectivity in areas with hilly and heavily foliated terrain. In addition, compared to hard-wired connectivity, there are security risks (unless robust security protocols are enabled); speeds are significantly slower (2 – 50 times slower); and the network can be less stable, due to interference from other wireless devices and networks, weather and line-of-sight problems.[6]
Rural Wireless-ISP installations are typically not commercial in nature and are instead a patchwork of systems built up by hobbyists mounting antennas on radio masts and towers, agricultural storage silos, very tall trees, or whatever other tall objects are available. There are currently a number of companies that provide this service. A wireless Internet access provider map for USA is publicly available for WISPS.
WorldSpace is a digital satellite radio network based in Washington DC. It covers most of Asia and Europe plus all of Africa by satellite. Beside the digital audio, users can receive one way broadband digital data transmission (150 Kilobit/second) from the satellite.
Advantages:
Disadvantages:
Traditionally, US Internet service providers have used an "unlimited time" or flat rate model, with pricing determined by the maximum bitrate chosen by the customer, rather than an hourly charge. With increased consumer demand for streaming content such as video on demand and peer-to-peer file sharing, the use of high bandwidth applications has increased rapidly.
For ISPs who are bandwidth limited, the flat rate pricing model may become unsustainable as demand for bandwidth increases. Fixed costs represent 80-90% of the cost of providing broadband service, and although most ISPs keep their cost secret, the total cost (January 2008) is estimated to be about $0.10 per gigabyte. Currently some ISPs estimate that about 5% of users consume about 50% of the total bandwidth.[10] To ensure these high-bandwidth users do not slow down the network, many ISPs have split their users’ bandwidth allocations into 'peak' and 'off peak', encouraging users to download large files late at night.[11]
In order to provide additional high bandwidth pay services[12] without incurring the additional costs of expanding current broadband infrastructure, Internet Service Providers are exploring new methods to cap current bandwidth usage by customers.[13] This is despite the lagging broadband infrastructure in the United States, according to the Economic Policy Institute: "The United States has also fallen behind other countries in the deployment of new broadband technologies."[14]
Some ISPs have begun experimenting with usage-based pricing, notably a Time Warner test in Beaumont, Texas.[15] The effort to expand usage-based pricing into the Rochester, New York area met with public resistance, however, and was abandoned.[16] Bell Canada has imposed bandwidth caps on customers.
To promote economic development and reduction of the digital divide, national broadband plans from around the world promote the universal availability of affordable broadband connectivity.
Internet access | ||||||||
---|---|---|---|---|---|---|---|---|
Network type | Wired | Wireless | ||||||
Optical | Coaxial cable | Twisted pair | Phone line | Power line | Unlicensed terrestrial bands | Licensed terrestrial bands | Satellite | |
LAN | Ethernet | G.hn | Ethernet | HomePNA · G.hn | G.hn · HomePlug Powerline Alliance | Wi-Fi · Bluetooth · DECT · Wireless USB | ||
WAN | PON · Ethernet | DOCSIS | Ethernet | Dial-up · ISDN · DSL | BPL | Muni Wi-Fi | GPRS · iBurst · WiBro/WiMAX · UMTS-TDD, HSPA · EVDO · LTE | Satellite |