Technologies
[edit]
When the Internet is accessed using a modem, digital data is converted to analog for transmission over analog networks such as the telephone and cable networks. A computer or other device accessing the Internet would either be connected directly to a modem that communicates with an Internet service provider (ISP) or the modem's Internet connection would be shared via a LAN which provides access in a limited area such as a home, school, computer laboratory, or office building.
Although a connection to a LAN may provide very high data rates within the LAN, actual Internet access speed is limited by the upstream link to the ISP. LANs may be wired or wireless. Ethernet over twisted pair cabling and Wi-Fi are the two most common technologies used to build LANs today, but ARCNET, Token Ring, LocalTalk, FDDI, and other technologies were used in the past.
Ethernet is the name of the IEEE 802.3 standard for physical LAN communication and Wi-Fi is a trade name for a wireless local area network (WLAN) that uses one of the IEEE 802.11 standards. Ethernet cables are interconnected via switches & routers. Wi-Fi networks are built using one or more wireless antennas called access points.
Many "modems" (cable modems, DSL gateways or Optical Network Terminals (ONTs)) provide the additional functionality to host a LAN so most Internet access today is through a LAN such as that created by a WiFi router connected to a modem or a combo modem router,[citation needed] often a very small LAN with just one or two devices attached. And while LANs are an important form of Internet access, this raises the question of how and at what data rate the LAN itself is connected to the rest of the global Internet. The technologies described below are used to make these connections, or in other words, how customers' modems (Customer-premises equipment) are most often connected to internet service providers (ISPs).
Dial-up technologies[edit]
Dial-up access[edit]
Main article: Dial-up Internet access
"Dial up modem noises"
Typical noises of a dial-up modem while establishing a connection with a local ISP in order to get access to the Internet.
Problems playing this file? See media help.
Dial-up Internet access uses a modem and a phone call placed over the public switched telephone network (PSTN) to connect to a pool of modems operated by an ISP. The modem converts a computer's digital signal into an analog signal that travels over a phone line's local loop until it reaches a telephone company's switching facilities or central office (CO) where it is switched to another phone line that connects to another modem at the remote end of the connection.
Operating on a single channel, a dial-up connection monopolizes the phone line and is one of the slowest methods of accessing the Internet. Dial-up is often the only form of Internet access available in rural areas as it requires no new infrastructure beyond the already existing telephone network to connect to the Internet. Typically, dial-up connections do not exceed a speed of 56 kbit/s, as they are primarily made using modems that operate at a maximum data rate of 56 kbit/s downstream (towards the end user) and 34 or 48 kbit/s upstream (toward the global Internet).
Multilink dial-up[edit]
Multilink dial-up provides increased bandwidth by channel bonding multiple dial-up connections and accessing them as a single data channel. It requires two or more modems, phone lines, and dial-up accounts, as well as an ISP that supports multilinking – and of course any line and data charges are also doubled. This inverse multiplexing option was briefly popular with some high-end users before ISDN, DSL and other technologies became available. Diamond and other vendors created special modems to support multilinking.
Hardwired broadband access[edit]
The term broadband includes a broad range of technologies, all of which provide higher data rate access to the Internet. The following technologies use wires or cables in contrast to wireless broadband described later.
Integrated Services Digital Network[edit]
Integrated Services Digital Network (ISDN) is a switched telephone service capable of transporting voice and digital data, and is one of the oldest Internet access methods. ISDN has been used for voice, video conferencing, and broadband data applications. ISDN was very popular in Europe, but less common in North America. Its use peaked in the late 1990s before the availability of DSL and cable modem technologies.
Basic rate ISDN, known as ISDN-BRI, has two 64 kbit/s "bearer" or "B" channels. These channels can be used separately for voice or data calls or bonded together to provide a 128 kbit/s service. Multiple ISDN-BRI lines can be bonded together to provide data rates above 128 kbit/s. Primary rate ISDN, known as ISDN-PRI, has 23 bearer channels (64 kbit/s each) for a combined data rate of 1.5 Mbit/s (US standard). An ISDN E1 (European standard) line has 30 bearer channels and a combined data rate of 1.9 Mbit/s. ISDN has been replaced by DSL technology, and it required special telephone switches at the service provider.
Leased lines[edit]
Leased lines are dedicated lines used primarily by ISPs, businesses, and other large enterprises to connect LANs and campus networks to the Internet using the existing infrastructure of the public telephone network or other providers. Delivered using wire, optical fiber, and radio, leased lines are used to provide Internet access directly as well as the building blocks from which several other forms of Internet access are created.
T-carrier technology dates to 1957 and provides data rates that range from 56 and 64 kbit/s (DS0) to 1.5 Mbit/s (DS1 or T1), to 45 Mbit/s (DS3 or T3). A T1 line carries 24 voice or data channels (24 DS0s), so customers may use some channels for data and others for voice traffic or use all 24 channels for clear channel data. A DS3 (T3) line carries 28 DS1 (T1) channels. Fractional T1 lines are also available in multiples of a DS0 to provide data rates between 56 and 1500 kbit/s. T-carrier lines require special termination equipment such as Data service units that may be separate from or integrated into a router or switch and which may be purchased or leased from an ISP. In Japan the equivalent standard is J1/J3. In Europe, a slightly different standard, E-carrier, provides 32 user channels (64 kbit/s) on an E1 (2.0 Mbit/s) and 512 user channels or 16 E1s on an E3 (34.4 Mbit/s).
Synchronous Optical Networking (SONET, in the U.S. and Canada) and Synchronous Digital Hierarchy (SDH, in the rest of the world) are the standard multiplexing protocols used to carry high-data-rate digital bit-streams over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At lower transmission rates data can also be transferred via an electrical interface. The basic unit of framing is an OC-3c (optical) or STS-3c (electrical) which carries 155.520 Mbit/s. Thus an OC-3c will carry three OC-1 (51.84 Mbit/s) payloads each of which has enough capacity to include a full DS3. Higher data rates are delivered in OC-3c multiples of four providing OC-12c (622.080 Mbit/s), OC-48c (2.488 Gbit/s), OC-192c (9.953 Gbit/s), and OC-768c (39.813 Gbit/s). The "c" at the end of the OC labels stands for "concatenated" and indicates a single data stream rather than several multiplexed data streams. Optical transport network (OTN) may be used instead of SONET for higher data transmission speeds of up to 400 Gbit/s per OTN channel.
The 1, 10, 40, and 100 Gigabit Ethernet IEEE standards (802.3) allow digital data to be delivered over copper wiring at distances to 100 m and over optical fiber at distances to 40 km.
Cable Internet access[edit]
Main article: Cable Internet access
Cable Internet provides access using a cable modem on hybrid fiber coaxial (HFC) wiring originally developed to carry television signals. Either fiber-optic or coaxial copper cable may connect a node to a customer's location at a connection known as a cable drop. Using a cable modem termination system, all nodes for cable subscribers in a neighborhood connect to a cable company's central office, known as the "head end." The cable company then connects to the Internet using a variety of means – usually fiber optic cable, digital satellite and microwave transmissions. Like DSL, broadband cable provides a continuous connection with an ISP.
Downstream, the direction toward the user, bit rates can be as much as 1000 Mbit/s in some countries, with the use of DOCSIS 3.1. Upstream traffic, originating at the user, ranges from 384 kbit/s to more than 50 Mbit/s. DOCSIS 4.0 promises up to 10 Gbit/s downstream and 6 Gbit/s upstream; however this technology has yet to be implemented in real-world usage. Broadband cable access tends to service fewer business customers because existing television cable networks tend to service residential buildings; commercial buildings do not always include wiring for coaxial cable networks. In addition, because broadband cable subscribers share the same local line, communications may be intercepted by neighboring subscribers. Cable networks regularly provide encryption schemes for data traveling to and from customers, but these schemes may be thwarted.
Digital subscriber line (DSL, ADSL, SDSL, and VDSL)[edit]
Digital subscriber line (DSL) service provides a connection to the Internet through the telephone network. Unlike dial-up, DSL can operate using a single phone line without preventing normal use of the telephone line for voice phone calls. DSL uses the high frequencies, while the low (audible) frequencies of the line are left free for regular telephone communication. These frequency bands are subsequently separated by filters installed at the customer's premises.
DSL originally stood for "digital subscriber loop". In telecommunications marketing, the term digital subscriber line is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed variety of DSL. The data throughput of consumer DSL services typically ranges from 256 kbit/s to 20 Mbit/s in the direction to the customer (downstream), depending on DSL technology, line conditions, and service-level implementation. In ADSL, the data throughput in the upstream direction (i.e., in the direction to the service provider) is lower than that in the downstream direction (i.e. to the customer), hence the designation of asymmetric. With a symmetric digital subscriber line (SDSL), the downstream and upstream data rates are equal.
Very-high-bit-rate digital subscriber line (VDSL or VHDSL, ITU G.993.1) is a digital subscriber line (DSL) standard approved in 2001 that provides data rates up to 52 Mbit/s downstream and 16 Mbit/s upstream over copper wires and up to 85 Mbit/s down- and upstream on coaxial cable. VDSL is capable of supporting applications such as high-definition television, as well as telephone services (voice over IP) and general Internet access, over a single physical connection.
VDSL2 (ITU-T G.993.2) is a second-generation version and an enhancement of VDSL. Approved in February 2006, it can provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. However, the maximum data rate is achieved at a range of about 300 meters and performance degrades as distance and loop attenuation increase.
DSL Rings[edit]
DSL Rings (DSLR) or Bonded DSL Rings is a ring topology that uses DSL technology over existing copper telephone wires to provide data rates of up to 400 Mbit/s.
Fiber to the home[edit]
Fiber-to-the-home (FTTH) is one member of the Fiber-to-the-x (FTTx) family that includes Fiber-to-the-building or basement (FTTB), Fiber-to-the-premises (FTTP), Fiber-to-the-desk (FTTD), Fiber-to-the-curb (FTTC), and Fiber-to-the-node (FTTN). These methods all bring data closer to the end user on optical fibers. The differences between the methods have mostly to do with just how close to the end user the delivery of fiber comes. All of these delivery methods are similar in function and architecture to hybrid fiber-coaxial (HFC) systems used to provide cable Internet access. Fiber internet connections to customers are either AON (Active optical network) or more commonly PON (Passive optical network). Examples of fiber optic internet access standards are G.984 (GPON, G-PON) and 10G-PON (XG-PON). ISPs may instead use Metro Ethernet as a replacement for T1 and Frame Relay lines for corporate and institutional customers, or offer carrier-grade Ethernet. Dedicated internet access (DIA) in which the bandwidth is not shared among customers, can be offered over PON fiber optic networks.
The use of optical fiber offers much higher data rates over relatively longer distances. Most high-capacity Internet and cable television backbones already use fiber optic technology, with data switched to other technologies (DSL, cable, LTE) for final delivery to customers. Fiber optic is immune to electromagnetic interference.
In 2010, Australia began rolling out its National Broadband Network across the country using fiber-optic cables to 93 percent of Australian homes, schools, and businesses. The project was abandoned by the subsequent LNP government, in favor of a hybrid FTTN design, which turned out to be more expensive and introduced delays. Similar efforts are underway in Italy, Canada, India, and many other countries (see Fiber to the premises by country).
Power-line Internet[edit]
Power-line Internet, also known as Broadband over power lines (BPL), carries Internet data on a conductor that is also used for electric power transmission. Because of the extensive power line infrastructure already in place, this technology can provide people in rural and low population areas access to the Internet with little cost in terms of new transmission equipment, cables, or wires. Data rates are asymmetric and generally range from 256 kbit/s to 2.7 Mbit/s.
Because these systems use parts of the radio spectrum allocated to other over-the-air communication services, interference between the services is a limiting factor in the introduction of power-line Internet systems. The IEEE P1901 standard specifies that all power-line protocols must detect existing usage and avoid interfering with it.
Power-line Internet has developed faster in Europe than in the U.S. due to a historical difference in power system design philosophies. Data signals cannot pass through the step-down transformers used and so a repeater must be installed on each transformer. In the U.S. a transformer serves a small cluster of from one to a few houses. In Europe, it is more common for a somewhat larger transformer to service larger clusters of from 10 to 100 houses. Thus a typical U.S. city requires an order of magnitude more repeaters than a comparable European city.
ATM and Frame Relay[edit]
Asynchronous Transfer Mode (ATM) and Frame Relay are wide-area networking standards that can be used to provide Internet access directly or as building blocks of other access technologies. For example, many DSL implementations use an ATM layer over the low-level bitstream layer to enable a number of different technologies over the same link. Customer LANs are typically connected to an ATM switch or a Frame Relay node using leased lines at a wide range of data rates.
While still widely used, with the advent of Ethernet over optical fiber, MPLS, VPNs and broadband services such as cable modem and DSL, ATM and Frame Relay no longer play the prominent role they once did.
Wireless broadband access[edit]
Wireless broadband is used to provide both fixed and mobile Internet access with the following technologies.
Satellite broadband[edit]
Satellite Internet access via VSAT in Ghana
Satellite Internet access provides fixed, portable, and mobile Internet access. Data rates range from 2 kbit/s to 1 Gbit/s downstream and from 2 kbit/s to 10 Mbit/s upstream. In the northern hemisphere, satellite antenna dishes require a clear line of sight to the southern sky, due to the equatorial position of all geostationary satellites. In the southern hemisphere, this situation is reversed, and dishes are pointed north. Service can be adversely affected by moisture, rain, and snow (known as rain fade). The system requires a carefully aimed directional antenna.
Satellites in geostationary Earth orbit (GEO) operate in a fixed position 35,786 km (22,236 mi) above the Earth's equator. At the speed of light (about 300,000 km/s or 186,000 miles per second), it takes a quarter of a second for a radio signal to travel from the Earth to the satellite and back. When other switching and routing delays are added and the delays are doubled to allow for a full round-trip transmission, the total delay can be 0.75 to 1.25 seconds. This latency is large when compared to other forms of Internet access with typical latencies that range from 0.015 to 0.2 seconds. Long latencies negatively affect some applications that require real-time response, particularly online games, voice over IP, and remote control devices. TCP tuning and TCP acceleration techniques can mitigate some of these problems. GEO satellites do not cover the Earth's polar regions. HughesNet, Exede, AT&T and Dish Network have GEO systems.
Satellite internet constellations in low Earth orbit (LEO, below 2,000 km or 1,243 miles) and medium Earth orbit (MEO, between 2,000 and 35,786 km or 1,243 and 22,236 miles) operate at lower altitudes, and their satellites are not fixed in their position above the Earth. Because they operate at a lower altitude, more satellites and launch vehicles are needed for worldwide coverage. This makes the initial required investment very large which initially caused OneWeb and Iridium to declare bankruptcy. However, their lower altitudes allow lower latencies and higher speeds which make real-time interactive Internet applications more feasible. LEO systems include Globalstar, Starlink, OneWeb and Iridium. The O3b constellation is a medium Earth-orbit system with a latency of 125 ms. COMMStellation™ is a LEO system, scheduled for launch in 2015,[needs update] that is expected to have a latency of just 7 ms.
Mobile broadband[edit]
Service mark for GSMA
Mobile broadband is the marketing term for wireless Internet access delivered through mobile phone towers (cellular networks) to computers, mobile phones (called "cell phones" in North America and South Africa, and "hand phones" in Asia), and other digital devices using portable modems. Some mobile services allow more than one device to be connected to the Internet using a single cellular connection using a process called tethering. The modem may be built into laptop computers, tablets, mobile phones, and other devices, added to some devices using PC cards, USB modems, and USB sticks or dongles, or separate wireless modems can be used.
New mobile phone technology and infrastructure are introduced periodically and generally involve a change in the fundamental nature of the service, non-backwards-compatible transmission technology, higher peak data rates, new frequency bands, and wider channel frequency bandwidth in Hertz. These transitions are referred to as generations. The first mobile data services became available during the second generation (2G).
Second generation (2G) from 1991:
Speeds in kbit/s
down and up
 ·  GSM CSD
9.6 kbit/s
 ·  CDPD
up to 19.2 kbit/s
 ·  GSM GPRS (2.5G)
56 to 115 kbit/s
 ·  GSM EDGE (2.75G) 
up to 237 kbit/s
Third generation (3G) from 2001:
Speeds in Mbit/s
down
up
 ·  UMTS W-CDMA
0.4 Mbit/s
 ·  UMTS HSPA
14.4
5.8
 ·  UMTS TDD
16 Mbit/s
 ·  CDMA2000 1xRTT
0.3
0.15
 ·  CDMA2000 EV-DO
2.5–4.9
0.15–1.8
 ·  GSM EDGE-Evolution 
1.6
0.5
Fourth generation (4G) from 2006:
Speeds in Mbit/s
down
up
 · 
HSPA+
21–672
5.8–168
 · 
Mobile WiMAX (802.16)
37–365
17–376
 · 
LTE
100–300
50–75
 · 
LTE-Advanced:
 
 
 ·  moving at higher speeds
100 Mbit/s
 
 ·  not moving or moving at lower speeds
up to 1000 Mbit/s
 · 
MBWA (802.20)
80 Mbit/s
The download (to the user) and upload (to the Internet) data rates given above are peak or maximum rates and end users will typically experience lower data rates.
WiMAX was originally developed to deliver fixed wireless service with wireless mobility added in 2005. CDPD, CDMA2000 EV-DO, and MBWA are no longer being actively developed.
In 2011, 90% of the world's population lived in areas with 2G coverage, while 45% lived in areas with 2G and 3G coverage.
5G was designed to be faster and have lower latency than its predecessor, 4G. It can be used for mobile broadband in smartphones or separate modems that emit WiFi or can be connected through USB to a computer, or for fixed wireless.
Fixed wireless[edit]
Fixed wireless internet connections that do not use a satellite nor are designed to support moving equipment such as smartphones due to the use of, for example, customer premises equipment such as antennas that can't be moved over a significant geographical area without losing the signal from the ISP, unlike smartphones. Microwave wireless broadband or 5G may be used for fixed wireless.
WiMAX[edit]
Worldwide Interoperability for Microwave Access (WiMAX) is a set of interoperable implementations of the IEEE 802.16 family of wireless-network standards certified by the WiMAX Forum. It enables "the delivery of last mile wireless broadband access as an alternative to cable and DSL". The original IEEE 802.16 standard, now called "Fixed WiMAX", was published in 2001 and provided 30 to 40 megabit-per-second data rates. Mobility support was added in 2005. A 2011 update provides data rates up to 1 Gbit/s for fixed stations. WiMax offers a metropolitan area network with a signal radius of about 50 km (30 miles), far surpassing the 30-metre (100-foot) wireless range of a conventional Wi-Fi LAN. WiMAX signals also penetrate building walls much more effectively than Wi-Fi. WiMAX is most often used as a fixed wireless standard.
Wireless ISP[edit]
Wi-Fi logo
Wireless Internet service providers (WISPs) operate independently of mobile phone operators. WISPs typically employ low-cost IEEE 802.11 Wi-Fi radio systems to link up remote locations over great distances (Long-range Wi-Fi), but may use other higher-power radio communications systems as well, such as microwave and WiMAX.
Wi-Fi range diagram
Traditional 802.11a/b/g/n/ac is an unlicensed omnidirectional service designed to span between 100 and 150 m (300 to 500 ft). By focusing the radio signal using a directional antenna (where allowed by regulations), 802.11 can operate reliably over a distance of many km(miles), although the technology's line-of-sight requirements hamper connectivity in areas with hilly or heavily foliated terrain. In addition, compared to hard-wired connectivity, there are security risks (unless robust security protocols are enabled); data rates are usually slower (2 to 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.
With the increasing popularity of unrelated consumer devices operating on the same 2.4 GHz band, many providers have migrated to the 5GHz ISM band. If the service provider holds the necessary spectrum license, it could also reconfigure various brands of off-the-shelf Wi-Fi hardware to operate on its own band instead of the crowded unlicensed ones. Using higher frequencies carries various advantages:
usually regulatory bodies allow for more power and the use of (better-) directional antennae,
there exists much more bandwidth to share, allowing both better throughput and improved coexistence,
there are fewer consumer devices that operate over 5 GHz than over 2.4 GHz, hence fewer interferers are present,
the shorter wavelengths don't propagate as well through walls and other structures, so much less interference leaks outside of the homes of consumers.
Proprietary technologies like Motorola Canopy & Expedience can be used by a WISP to offer wireless access to rural and other markets that are hard to reach using Wi-Fi or WiMAX. There are a number of companies that provide this service.
Local Multipoint Distribution Service[edit]
Local Multipoint Distribution Service (LMDS) is a broadband wireless access technology that uses microwave signals operating between 26 GHz and 29 GHz. Originally designed for digital television transmission (DTV), it is conceived as a fixed wireless, point-to-multipoint technology for utilization in the last mile. Data rates range from 64 kbit/s to 155 Mbit/s. Distance is typically limited to about 1.5 miles (2.4 km), but links of up to 5 miles (8 km) from the base station are possible in some circumstances.
LMDS has been surpassed in both technological and commercial potential by the LTE and WiMAX standards.
Hybrid Access Networks[edit]
See also: Hybrid Access Networks
In some regions, notably in rural areas, the length of the copper lines makes it difficult for network operators to provide high-bandwidth services. One alternative is to combine a fixed-access network, typically XDSL, with a wireless network, typically LTE. The Broadband Forum has standardized an architecture for such Hybrid Access Networks.
Non-commercial alternatives for using Internet services[edit]
See also: Project Loon
Grassroots wireless networking movements[edit]
Deploying multiple adjacent Wi-Fi access points is sometimes used to create city-wide wireless networks. It is usually ordered by the local municipality from commercial WISPs.
Grassroots efforts have also led to wireless community networks widely deployed in numerous countries, both developing and developed ones. 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.
Where radio spectrum regulation is not community-friendly, the channels are crowded or when equipment can not be afforded by residents, free-space optical communication can also be deployed similarly for point-to-point transmission in air (rather than in fiber optic cable).
Packet radio[edit]
Main articles: Packet radio and AMPRNet
Packet radio connects computers or whole networks operated by radio amateurs with the option to access the Internet. Note that as per the regulatory rules outlined in the HAM license, Internet access and email should be strictly related to the activities of hardware amateurs.
Sneakernet[edit]
Main article: Sneakernet
The term, a tongue-in-cheek play on net(work) as in Internet or Ethernet, refers to the wearing of sneakers as the transport mechanism for the data.
For those who do not have access to or can not afford broadband at home, downloading large files and disseminating information is done by transmission through workplace or library networks, taken home and shared with neighbors by sneakernet. The Cuban El Paquete Semanal is an organized example of this.
There are various decentralized, delay-tolerant peer-to-peer applications which aim to fully automate this using any available interface, including both wireless (Bluetooth, Wi-Fi mesh, P2P or hotspots) and physically connected ones (USB storage, Ethernet, etc.).
Sneakernets may also be used in tandem with computer network data transfer to increase data security or overall throughput for big data use cases. Innovation continues in this area to this day; for example, AWS has recently announced Snowball, and bulk data processing is also done in a similar fashion by many research institutes and government agencies.