Bandwidth (computing)

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In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, [1] data bandwidth, [2] or digital bandwidth. [3] [4]

Contents

This definition of bandwidth is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics [ citation needed ], in which bandwidth is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel.

Network bandwidth capacity

The term bandwidth sometimes defines the net bit rate 'peak bit rate', 'information rate,' or physical layer 'useful bit rate', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth tests measure the maximum throughput of a computer network. The maximum rate that can be sustained on a link are limited by the Shannon–Hartley channel capacity for these communication systems, which is dependent on the bandwidth in hertz and the noise on the channel.

Network bandwidth consumption

The consumed bandwidth in bit/s, corresponds to achieved throughput or goodput, i.e., the average rate of successful data transfer through a communication path. The consumed bandwidth can be affected by technologies such as bandwidth shaping, bandwidth management, bandwidth throttling, bandwidth cap, bandwidth allocation (for example bandwidth allocation protocol and dynamic bandwidth allocation), etc. A bit stream's bandwidth is proportional to the average consumed signal bandwidth in hertz (the average spectral bandwidth of the analog signal representing the bit stream) during a studied time interval.

Channel bandwidth may be confused with useful data throughput (or goodput). For example, a channel with x bps may not necessarily transmit data at x rate, since protocols, encryption, and other factors can add appreciable overhead. For instance, much internet traffic uses the transmission control protocol (TCP), which requires a three-way handshake for each transaction. Although in many modern implementations the protocol is efficient, it does add significant overhead compared to simpler protocols. Also, data packets may be lost, which further reduces the useful data throughput. In general, for any effective digital communication, a framing protocol is needed; overhead and effective throughput depends on implementation. Useful throughput is less than or equal to the actual channel capacity minus implementation overhead.

Asymptotic bandwidth

The asymptotic bandwidth (formally asymptotic throughput) for a network is the measure of maximum throughput for a greedy source, for example when the message size (the number of packets per second from a source) approaches close to the maximum amount. [5]

Asymptotic bandwidths are usually estimated by sending a number of very large messages through the network, measuring the end-to-end throughput. As other bandwidths, the asymptotic bandwidth is measured in multiples of bits per seconds. Since bandwidth spikes can skew the measurement, carriers often use the 95th percentile method. This method continuously measures bandwidth usage and then removes the top 5 percent. [6]

Multimedia bandwidth

Digital bandwidth may also refer to: multimedia bit rate or average bitrate after multimedia data compression (source coding), defined as the total amount of data divided by the playback time.

Due to the impractically high bandwidth requirements of uncompressed digital media, the required multimedia bandwidth can be significantly reduced with data compression. [7] The most widely used data compression technique for media bandwidth reduction is the discrete cosine transform (DCT), which was first proposed by Nasir Ahmed in the early 1970s. [8] DCT compression significantly reduces the amount of memory and bandwidth required for digital signals, capable of achieving a data compression ratio of up to 100:1 compared to uncompressed media. [9]

Bandwidth in web hosting

In Web hosting service, the term bandwidth is often incorrectly used to describe the amount of data transferred to or from the website or server within a prescribed period of time, for example bandwidth consumption accumulated over a month measured in gigabytes per month.[ citation needed ] The more accurate phrase used for this meaning of a maximum amount of data transfer each month or given period is monthly data transfer.

A similar situation can occur for end user ISPs as well, especially where network capacity is limited (for example in areas with underdeveloped internet connectivity and on wireless networks).

Internet connection bandwidth

This table shows the maximum bandwidth (the physical layer net bitrate) of common Internet access technologies. For more detailed lists see

56 kbit/sModem / Dialup
1.5 Mbit/s ADSL Lite
1.544 Mbit/s T1/DS1
2.048 Mbit/sE1 / E-carrier
4 Mbit/sADSL1
10 Mbit/s Ethernet
11 Mbit/sWireless 802.11b
24 Mbit/sADSL2+
44.736 Mbit/s T3/DS3
54 Mbit/sWireless 802.11g
100 Mbit/s Fast Ethernet
155 Mbit/s OC3
600 Mbit/sWireless 802.11n
622 Mbit/s OC12
1 Gbit/s Gigabit Ethernet
1.3 Gbit/sWireless 802.11ac
2.5 Gbit/s OC48
5 Gbit/s SuperSpeed USB
7 Gbit/sWireless 802.11ad
9.6 Gbit/s OC192
10 Gbit/s 10 Gigabit Ethernet, SuperSpeed USB 10 Gbit/s
20 Gbit/s SuperSpeed USB 20 Gbit/s
40 Gbit/s Thunderbolt 3
100 Gbit/s 100 Gigabit Ethernet

Edholm's law

Edholm's law, proposed by and named after Phil Edholm in 2004, [10] holds that the bandwidth of telecommunication networks double every 18 months, which has proven to be true since the 1970s. [10] [11] The trend is evident in the cases of Internet, [10] cellular (mobile), wireless LAN and wireless personal area networks. [11]

The MOSFET (metal-oxide-semiconductor field-effect transistor) is the most important factor enabling the rapid increase in bandwidth. [12] The MOSFET (MOS transistor) was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, [13] [14] [15] and went on to become the basic building block of modern telecommunications technology. [16] [17] [18] Continuous MOSFET scaling, along with various advances in MOS technology, has enabled both Moore's law (transistor counts in integrated circuit chips doubling every two years) and Edholm's law (communication bandwidth doubling every 18 months). [12]

Related Research Articles

In general terms, throughput is the rate of production or the rate at which something is processed.

Digital electronics Electronic circuits that utilize digital signals

Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. This is in contrast to analog electronics and analog signals.

Telephony is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone.

Telecommunications network network to enable telecommunication between different terminals

A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit switching, message switching, or packet switching, to pass messages and signals. For each message, multiple nodes may cooperate to pass the message from an originating node to the a destination node, via multiple network hops. For this routing function each node in the network is assigned a network address for identification and locating it on the network. The collection of addresses in the network is called the address space of the network.

Information Age Current historical era

The Information Age is a historical period that began in the late 20th century, characterized by a rapid epochal shift from the traditional industry established by the Industrial Revolution to an economy primarily based upon information technology. The onset of the Information Age can be associated with the development of transistor technology, particularly the MOSFET, which became the fundamental building block of digital electronics and revolutionized modern technology.

Digital signal processor specialized microprocessor optimized for digital signal processing

A digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on MOS integrated circuit chips. They are widely used in audio signal processing, telecommunications, digital image processing, radar, sonar and speech recognition systems, and in common consumer electronic devices such as mobile phones, disk drives and high-definition television (HDTV) products.

Wireless transfer of information or power that does not require the use of physical wires

Wireless communication is the electromagnetic transfer of information between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mouse, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications include the use of other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound.

In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time.

Internet access Individual connection to the internet

Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Internet access is sold by Internet service providers (ISPs) delivering connectivity at a wide range of data transfer rates via various networking technologies. Many organizations, including a growing number of municipal entities, also provide cost-free wireless access and landlines.


Throughput of a network can be measured using various tools available on different platforms. This page explains the theory behind what these tools set out to measure and the issues regarding these measurements.

A mixed-signal integrated circuit is any integrated circuit that has both analog circuits and digital circuits on a single semiconductor die. In real-life applications mixed-signal designs are everywhere, for example, smart mobile phones. Mixed-signal ICs also process both analog and digital signals together. For example, an analog-to-digital converter is a mixed-signal circuit. Mixed-signal circuits or systems are typically cost-effective solutions for building any modern consumer electronics applications.

Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the information rate that can be transmitted over a given bandwidth in a specific communication system. It is a measure of how efficiently a limited frequency spectrum is utilized by the physical layer protocol, and sometimes by the media access control.

In computer networking, wire speed or wirespeed refers to the hypothetical peak physical layer net bitrate of a cable combined with a certain digital communication device, interface, or port. For example, the wire speed of Fast Ethernet is 100 Mbit/s also known as the peak bitrate, connection speed, useful bit rate, information rate, or digital bandwidth capacity. The wire speed is the data transfer rate that a telecommunications standard provides at a reference point between the physical layer and the datalink layer.

History of telecommunication aspect of history relating to telecommunications

The history of telecommunication began with the use of smoke signals and drums in Africa, Asia, and the Americas. In the 1790s, the first fixed semaphore systems emerged in Europe. However, it was not until the 1830s that electrical telecommunication systems started to appear. This article details the history of telecommunication and the individuals who helped make telecommunication systems what they are today. The history of telecommunication is an important part of the larger history of communication.

In computing, computer performance is the amount of useful work accomplished by a computer system. Outside of specific contexts, computer performance is estimated in terms of accuracy, efficiency and speed of executing computer program instructions. When it comes to high computer performance, one or more of the following factors might be involved:

Digital Revolution change from analog, mechanical, and electronic technology to digital technology

The Digital Revolution is the shift from mechanical and analogue electronic technology to digital electronics which began in the latter half of the 20th century, with the adoption and proliferation of digital computers and digital record-keeping, that continues to the present day. Implicitly, the term also refers to the sweeping changes brought about by digital computing and communication technology during this period. Analogous to the Agricultural Revolution and Industrial Revolution, the Digital Revolution marked the beginning of the Information Age.

Edholm's law, proposed by and named after Phil Edholm, refers to the observation that the three categories of telecommunication, namely wireless (mobile), nomadic and wired networks (fixed), are in lockstep and gradually converging. Edholm's law also holds that data rates for these telecommunications categories increase on similar exponential curves, with the slower rates trailing the faster ones by a predictable time lag. Edholm's law predicts that the bandwidth and data rates double every 18 months, which has proven to be true since the 1970s. The trend is evident in the cases of Internet, cellular (mobile), wireless LAN and wireless personal area networks.

Telecommunication Transmission of information between locations using electromagnetics

Telecommunication is the exchange of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology. It is transmitted through a transmission medium, such as over physical media, for example, over electrical cable, or via electromagnetic radiation through space such as radio or light. Such transmission paths are often divided into communication channels which afford the advantages of multiplexing. Since the Latin term communicatio is considered the social process of information exchange, the term telecommunications is often used in its plural form because it involves many different technologies.

MOSFET applications Wikimedia list article

The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of insulated-gate field-effect transistor (IGFET) that is fabricated by the controlled oxidation of a semiconductor, typically silicon. The voltage of the covered gate determines the electrical conductivity of the device; this ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. The MOSFET was invented by Egyptian engineer Mohamed M. Atalla and Korean engineer Dawon Kahng at Bell Labs in 1959. It is the basic building block of modern electronics, and the most frequently manufactured device in history, with an estimated total of 13 sextillion (1.3 × 1022) MOSFETs manufactured between 1960 and 2018.

References

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