|
Contention (telecommunications)
In statistical time division multiplexing, contention is a media access method that is used to share a broadcast medium. In contention, any computer in the network can transmit data at any time (first come-first served). This system breaks down when two computers attempt to transmit at the same time. This is known as a collision. To avoid collisions, a carrier sensing mechanism is used. Here each computer listens to the network before attempting to transmit. If the network is busy, it waits until network quiets down. In carrier detection, computers continue to listen to the network as they transmit. If computer detects another signal that interferes with the signal it is sending, it stops transmitting. Both computers then wait for a random amount of time and attempt to transmit. Contention methods are most popular media access control method on LANs. Collision detection and recovery One method to handle collisions in a contention based system is to optimize collision detection an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Time Division 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] |
Multiple Access With Collision Avoidance
Multiple Access with Collision Avoidance (MACA) is a slotted media access control protocol used in wireless LAN data transmission to avoid collisions caused by the hidden station problem and to simplify exposed station problem. The basic idea of MACA is a wireless network node makes an announcement before it sends the data frame to inform other nodes to keep silent. When a node wants to transmit, it sends a signal called ''Request-To-Send'' (RTS) with the length of the data frame to send. If the receiver allows the transmission, it replies the sender a signal called ''Clear-To-Send'' (CTS) with the length of the frame that is about to receive. Meanwhile, a node that hears RTS should remain silent to avoid conflict with CTS; a node that hears CTS should keep silent until the data transmission is complete. WLAN data transmission collisions may still occur, and the MACA for Wireless ( MACAW) is introduced to extend the function of MACA. It requires nodes sending acknowledgements aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contention Free Pollable
Contention-free pollable (CF-Pollable) is a state of operation for wireless networking nodes. The condition is saying that the node is able to use the Point Coordination Function, as opposed to the Distributed Coordination Function, within a wireless LAN. A device that is able to use point coordination function is one that is able to participate in a method to provide limited Quality of service (for time sensitive data) within the network. See also *Contention (telecommunications) In statistical time division multiplexing, contention is a media access method that is used to share a broadcast medium. In contention, any computer in the network can transmit data at any time (first come-first served). This system breaks down ... References {{DEFAULTSORT:Contention Free Pollable Wireless networking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Master Station
In telecommunication, a master station is a station that controls or coordinates the activities of other stations in the system. Examples: *In a data network, the control station may designate a master station to ensure data transfer to one or more slave stations.Federal Standard 1037C Such a master station controls one or more data links of the data communications network at any given instant. The assignment of master status to a given station is temporary and is controlled by the control station according to the procedures set forth in the operational protocol. Master status is normally conferred upon a station so that it may transmit a message, but a station need not have a message to send to be designated the master station. * In navigation systems using precise time dissemination, the master station is a station that has the clock that is used to synchronize the clocks of subordinate stations. * In basic mode link control, the master station is a data station that has accepted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contention Ratio
In computer networking, the contention ratio is the ratio of the potential maximum demand to the actual bandwidth. The higher the contention ratio, the greater the number of users that may be trying to use the actual bandwidth at any one time and, therefore, the lower the effective bandwidth offered, especially at peak times.UK OFCOM research report annex on broadban/ref> A ''contended service'' is a service which offers the users of the network a minimum statistically guaranteed contention ratio, while typically offering peaks of usage of up to the maximum bandwidth supplied to the user. Contended services are usually much cheaper to provide than uncontended services, although they only reduce the backbone traffic costs for the users, and do not reduce the costs of providing and maintaining equipment for connecting to the network. Examples by country In the United Kingdom, a Rate Adaptive Digital Subscriber Line ( RADSL) connection used to be marketed with a contention ratio bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shared Resource
In computing, a shared resource, or network share, is a System resource, computer resource made available from one Host (network), host to other hosts on a computer network. It is a device or piece of information on a computer that can be remotely accessed from another computer transparently as if it were a resource in the local machine. Network sharing is made possible by inter-process communication over the network. Some examples of shareable resources are computer programs, Data (computing), data, Data storage device, storage devices, and Printer (computing), printers. E.g. shared file access (also known as disk sharing and folder sharing), shared printer access, shared scanner access, etc. The shared resource is called a shared disk, shared folder or shared document The term ''file sharing'' traditionally means shared file access, especially in the context of operating systems and local area network, LAN and Intranet services, for example in Microsoft Windows documentation. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Building
A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, prestige, and aesthetic reasons. To better understand the term ''building'' compare the list of nonbuilding structures. Buildings serve several societal needs – primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical division of the human habitat (a place of comfort and safety) and the ''outside'' (a place that at times may be harsh and harmful). Ever since the first cave paintings, buildings have also become objects or canvasses of much artist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System
A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment (systems), environment, is described by its boundaries, structure and purpose and expressed in its functioning. Systems are the subjects of study of systems theory and other systems sciences. Systems have several common properties and characteristics, including structure, function(s), behavior and interconnectivity. Etymology The term ''system'' comes from the Latin word ''systēma'', in turn from Greek language, Greek ''systēma'': "whole concept made of several parts or members, system", literary "composition"."σύστημα" Henry George Liddell, Robert Scott, ''A Greek–English Lexicon'', on Per ... [...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 drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carrier Sense Multiple Access
Carrier-sense multiple access (CSMA) is a medium access control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus or a band of the electromagnetic spectrum. Under CSMA, a transmitter uses a carrier-sense mechanism to determine whether another transmission is in progress before initiating a transmission. That is, it tries to detect the presence of a carrier signal from another node before attempting to transmit. If a carrier is sensed, the node waits for the transmission in progress to end before initiating its own transmission. Using CSMA, multiple nodes may, in turn, send and receive on the same medium. Transmissions by one node are generally received by all other nodes connected to the medium. Variations on basic CSMA include addition of collision-avoidance (CSMA/CA), collision-detection (CSMA/CD) and collision-resolution techniques. Access modes Variations of CSMA use different a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collision (telecommunications)
A collision is the situation that occurs when two or more demands are made simultaneously on equipment that can handle only one at any given instant.Source: from Federal Standard 1037C and from MIL-STD-188 It may refer to: * Collision domain, a physical network segment where data packets can "collide" ** Carrier-sense multiple access with collision avoidance, (CSMA/CA) used for example with wireless LANs ** Carrier-sense multiple access with collision detection, (CSMA/CD) used with Ethernet * Late collision, a specific type of collision that should not occur on properly operating networks * Local collision is a collision that occurs in the network interface rather than on the network itself See also * Collision (other) * Contention (telecommunications) In statistical time division multiplexing, contention is a media access method that is used to share a broadcast medium. In contention, any computer in the network can transmit data at any time (first come-first served). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aloha Protocol
ALOHAnet, also known as the ALOHA System, or simply ALOHA, was a pioneering computer networking system developed at the University of Hawaii. ALOHAnet became operational in June 1971, providing the first public demonstration of a wireless packet data network. ALOHA originally stood for Additive Links On-line Hawaii Area. The ALOHAnet used a new method of medium access, called ''ALOHA random access'', and experimental ultra high frequency (UHF) for its operation. In the 1970s ALOHA random access was employed in the nascent Ethernet cable based network and then in the Marisat (now Inmarsat) satellite network. In the early 1980s frequencies for mobile networks became available, and in 1985 frequencies suitable for what became known as Wi-Fi were allocated in the US. These regulatory developments made it possible to use the ALOHA random-access techniques in both Wi-Fi and in mobile telephone networks. ALOHA channels were used in a limited way in the 1980s in 1G mobile phones fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
