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Packet Switching
In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. In the early 1960s, American computer scientist Paul Baran developed the concept that he called "distributed adaptive message block switching", with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted then-established principles of pre- allocation of network bandwidth, exemplified by the development of telecommunications in the Bell S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Donald Davies
Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL). In 1965 he conceived of packet switching, which is today the dominant basis for data communications in computer networks worldwide. Davies proposed a commercial national data network in the United Kingdom and designed and built the local-area NPL network to demonstrate the technology. Many of the wide-area packet-switched networks built in the 1970s were similar "in nearly all respects" to his original 1965 design. The ARPANET project credited Davies for his influence, which was key to the development of the Internet. Davies' work was independent of the work of Paul Baran in the United States who had a similar idea in the early 1960s, and who also provided input to the ARPANET project, after his work was highlighted by Davies' team. Early life Davies was born in Treorchy in the Rhondda Valley, Wales. His father, a clerk at a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Bandwidth Allocation
Dynamic bandwidth allocation is a technique by which traffic bandwidth in a shared telecommunications medium can be allocated on demand and fairly between different users of that bandwidth. This is a form of bandwidth management, and is essentially the same thing as statistical multiplexing. Where the sharing of a link adapts in some way to the instantaneous traffic demands of the nodes connected to the link. Dynamic bandwidth allocation takes advantage of several attributes of shared networks: # all users are typically not connected to the network at one time # even when connected, users are not transmitting data (or voice or video) at all times # most traffic occurs in bursts—there are gaps between packets of information that can be filled with other user traffic Different network protocols implement dynamic bandwidth allocation in different ways. These methods are typically defined in standards developed by standards bodies such as the ITU, IEEE, FSAN, or IETF. One exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Multiplexing
Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or data streams. The link sharing is adapted to the instantaneous traffic demands of the data streams that are transferred over each channel. This is an alternative to creating a fixed sharing of a link, such as in general time division multiplexing (TDM) and frequency division multiplexing (FDM). When performed correctly, statistical multiplexing can provide a link utilization improvement, called the ''statistical multiplexing gain''. Statistical multiplexing is facilitated through packet mode or packet-oriented communication, which among others is utilized in packet switched computer networks. Each stream is divided into packets that normally are delivered asynchronously in a first-come first-served fashion. In alternative fashion, the pack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies. The nodes of a computer network can include personal computers, servers, networking hardware, or other specialised or general-purpose hosts. They are identified by network addresses, and may have hostnames. Hostnames serve as memorable labels for the nodes, rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the transmission medium used to carry signals, bandwidth, communications pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Bit Rate
Variable bitrate (VBR) is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows a higher bitrate (and therefore more storage space) to be allocated to the more complex segments of media files while less space is allocated to less complex segments. The average of these rates can be calculated to produce an average bitrate for the file. MP3, WMA and AAC audio files can optionally be encoded in VBR, while Opus and Vorbis are encoded in VBR by default. Variable bit rate encoding is also commonly used on MPEG-2 video, MPEG-4 Part 2 video ( Xvid, DivX, etc.), MPEG-4 Part 10/H.264 video, Theora, Dirac and other video compression formats. Additionally, variable rate encoding is inherent in lossless compression schemes such as FLAC and Apple Lossless. Advantages and disadvantages of VBR The advantages of VBR are that i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rowman & Littlefield
Rowman & Littlefield Publishing Group is an independent publishing house founded in 1949. Under several imprints, the company offers scholarly books for the academic market, as well as trade books. The company also owns the book distributing company National Book Network based in Lanham, Maryland. History The current company took shape when University Press of America acquired Rowman & Littlefield in 1988 and took the Rowman & Littlefield name for the parent company. Since 2013, there has also been an affiliated company based in London called Rowman & Littlefield International. It is editorially independent and publishes only academic books in Philosophy, Politics & International Relations and Cultural Studies. The company sponsors the Rowman & Littlefield Award in Innovative Teaching, the only national teaching award in political science given in the United States. It is awarded annually by the American Political Science Association for people whose innovations have advanced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Traffic
Network traffic or data traffic is the amount of data moving across a network at a given point of time. Network data in computer networks is mostly encapsulated in network packets, which provide the load in the network. Network traffic is the main component for network traffic measurement, network traffic control and simulation. * Network traffic control - managing, prioritizing, controlling or reducing the network traffic * Network traffic measurement - measuring the amount and type of traffic on a particular network * Network traffic simulation - to measure the efficiency of a communications network * Traffic generation model - is a stochastic model of the traffic flows or data sources in a communication computer network. Proper analysis of network traffic provides the organization with the network security as a benefit - unusual amount of traffic in a network is a possible sign of an attack. Network traffic reports provide valuable insights into preventing such attacks. Traffic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmission (telecommunications)
In telecommunications, transmission is the process of sending or propagating an analog or digital signal via a medium that is wired, wireless, or fiber-optic. Transmission technologies typically refer to physical layer protocol duties such as modulation, demodulation, line coding, equalization, error control, bit synchronization and multiplexing, but it may also involve higher-layer protocol duties, for example, digitizing an analog signal, and data compression. Transmission of a digital message, or of a digitized analog signal, is known as data transmission. Examples of transmission are the sending of signals with limited duration, for example, a block or packet of data, a phone call, or an email. See also *Radio transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is appli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication Channel
A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for information transfer of, for example, a digital bit stream, from one or several '' senders'' to one or several '' receivers''. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second. Communicating an information signal across distance requires some form of pathway or medium. These pathways, called communication channels, use two types of media: Transmission line (e.g. twisted-pair, coaxial, and fiber-optic cable) and broadcast (e.g. microwave, satellite, radio, and infrared). In information theory, a channel refers to a theoretical ''channel model'' with certain error characteristics. In this more general view, a storage device is also a communication channel, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Routing
Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone network (PSTN), and computer networks, such as the Internet. In packet switching networks, routing is the higher-level decision making that directs network packets from their source toward their destination through intermediate network nodes by specific packet forwarding mechanisms. Packet forwarding is the transit of network packets from one network interface to another. Intermediate nodes are typically network hardware devices such as routers, gateways, firewalls, or switches. General-purpose computers also forward packets and perform routing, although they have no specially optimized hardware for the task. The routing process usually directs forwarding on the basis of routing tables. Routing tables maintain a record of the routes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Switching
In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. In the early 1960s, American computer scientist Paul Baran developed the concept that he called "distributed adaptive message block switching", with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted then-established principles of pre- allocation of network bandwidth, exemplified by the development of telecommunications in the Bell S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
