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Q.2931
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of ''Digital Subscriber Signalling System No. 1''. Unlike connectionless systems like UDP, ISDN is connection oriented and uses explicit signalling to manage call state: Q.931. Q.931 typically does not carry user data. Q.931 does not have a direct equivalent in the Internet Protocol stack, but can be compared to SIP. Q.931 does not provide flow control or perform retransmission, since the underlying layers are assumed to be reliable and the circuit-oriented nature of ISDN allocates bandwidth in fixed increments of 64 kbit/s. Amongst other things, Q.931 manages connection setup and breakdown. Like TCP, Q.931 documents both the protocol itself and a protocol state machine. Q.931 was designed for ISDN call establishment, maintenance, and release of network connections between two DTEs on the ISDN D channel. Q.931 has more recently been used as part of the VoIP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information Element
An information element, sometimes informally referred to as a field, is an item in Q.931 and Q.2931 messages, IEEE 802.11 management frames, and cellular network messages sent between a base transceiver station and a mobile phone or similar piece of user equipment. Section 11.2.1 An information element is often a type–length–value item, containing 1) a type (which corresponds to the label of a field), a length indicator, and a value, although any combination of one or more of those parts is possible. A single message may contain multiple information elements. The abbreviation IE is found in many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-T
The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Communication Technology such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The first meeting of the World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, took place on 1 March of that year. ITU-T has a permanent secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Chaesub Lee (of South Korea), whose first 4-year term commenced on 1 January 2015, and whose second 4-year term commenced on 1 January 2019. Chaesub Lee succeeded Malcolm Johnson (Director), Malc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D Channel
D channel (delta channel) is a telecommunications term which refers to the ISDN channel in which the control and signalling information is carried. The bit rate of the D channel of a basic rate interface is 16 kbit/s, whereas it amounts to 64 kbit/s on a primary rate interface. For DSS1 signalling, the D channel layer 2 protocol is Q.921 also called LAPD and it carries Layer 3 messages according to Q.931 protocol. See also * B channel * H channel {{unreferenced, date=June 2012 In the Integrated Services Digital Network (ISDN), a high-speed communication channel comprising multiple aggregated low-speed channels to accommodate bandwidth-intensive applications such as file transfer, videoconfe ... {{telecomm-stub Integrated Services Digital Network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jitter
In electronics and telecommunications, jitter is the deviation from true periodicity of a presumably periodic signal, often in relation to a reference clock signal. In clock recovery applications it is called timing jitter. Jitter is a significant, and usually undesired, factor in the design of almost all communications links. Jitter can be quantified in the same terms as all time-varying signals, e.g., root mean square (RMS), or peak-to-peak displacement. Also, like other time-varying signals, jitter can be expressed in terms of spectral density. Jitter period is the interval between two times of maximum effect (or minimum effect) of a signal characteristic that varies regularly with time. Jitter frequency, the more commonly quoted figure, is its inverse. ITU-T G.810 classifies jitter frequencies below 10 Hz as wander and frequencies at or above 10 Hz as jitter. Jitter may be caused by electromagnetic interference and crosstalk with carriers of other signals. Jitte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic Management
Traffic management is a key branch within logistics. It concerns the planning control and purchasing of transport services needed to physically move vehicles (for example aircraft, road vehicles, rolling stock and watercraft) and freight. Traffic management is implemented by people working with different job titles in different branches: * Within freight and cargo logistics: traffic manager, assessment of hazardous and awkward materials, carrier choice and fees, demurrage, documentation, expediting, freight consolidation, insurance, reconsignment and tracking * Within air traffic management: air traffic controller * Within rail traffic management: rail traffic controller, train dispatcher or signalman * Within road traffic management: traffic controller Traffic Control Management is the design, auditing and implementation of traffic control plans at worksites and civil infrastructure projects. Traffic Management can include: flagging, lane closures, detours, full freeway closure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous Transfer Mode
Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by American National Standards Institute (ANSI) and ITU-T (formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of the Broadband Integrated Services Digital Network as defined in the late 1980s, and designed to integrate telecommunication networks. It can handle both traditional high-throughput data traffic and real-time, low-latency content such as telephony (voice) and video.ATM Forum, The User Network Interface (UNI), v. 3.1, , Prentice Hall PTR, 1995, page 2. ATM provides functionality that uses features of circuit switching and packet switching networks by using asynchronous time-division multiplexing.McDysan (1999), p. 287. In the OSI reference model data link layer (layer 2), the basic transfer units are called '' frames''. In ATM these frames are of a fixed length (53 octets) called ''cells''. This differs from approaches such as Internet Pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BISDN
In the 1980s, the telecommunications industry expected that digital services would follow much the same pattern as voice services did on the public switched telephone network, and conceived an end-to-end circuit switched service, known as Broadband Integrated Services Digital Network (B-ISDN). History Before B-ISDN, the original ISDN attempted to substitute the analog telephone system with a digital system which was appropriate for both voice and non-voice traffic. Obtaining worldwide agreement on the basic rate interface standard was expected to lead to a large user demand for ISDN equipment, hence leading to mass production and inexpensive ISDN chips. However, the standardization process took years while computer network technology moved rapidly. Once the ISDN standard was finally agreed upon and products were available, it was already obsolete. For home use the largest demand for new services was video and voice transfer, but the ISDN basic rate lacks the necessary channel capac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DSS1
Digital Subscriber Signalling System No. 1 (DSS1) is a digital signalling protocol (D channel protocol) used for the ISDN. It is defined by ITU-T I.411 (ETS 300 102). It supports Bearer Capability, Low Level Compatibility and High Level Compatibility, ANI, DNIS and redirected number signaling in both directions. A standard developed by ETSI for Europe is known as Euro-ISDN or E-DSS1 or simply EDSS1 (European DSS1). DSS1/EDSS1 protocol, in contrast, for example, to the protocol QSIG, designed for use as access to public ISDN and asymmetric in the sense that it suggests a link with the network side at one end (digital public telephone exchange) and the user (private branch exchange, PBX) - at the other. Since the market for ISDN equipment was open, ETSI provided guidance to suppliers of ISDN equipment by means of the minimum requirements for inter-connectivity to ISDN networks. These documents, called NET3 for BRI and NET5 for PRI lines, described a set of protocol tests term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Switching Center
Network switching subsystem (NSS) (or GSM core network) is the component of a GSM system that carries out call out and mobility management functions for mobile phones roaming on the network of base stations. It is owned and deployed by mobile phone operators and allows mobile devices to communicate with each other and telephones in the wider public switched telephone network (PSTN). The architecture contains specific features and functions which are needed because the phones are not fixed in one location. The NSS originally consisted of the circuit-switched core network, used for traditional GSM services such as voice calls, SMS, and circuit switched data calls. It was extended with an overlay architecture to provide packet-switched data services known as the GPRS core network. This allows mobile phones to have access to services such as WAP, MMS and the Internet. Mobile switching center (MSC) Description The mobile switching center (MSC) is the primary service del ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Equipment
In the Universal Mobile Telecommunications System (UMTS) and 3GPP Long Term Evolution (LTE), user equipment (UE) is any device used directly by an end-user to communicate. It can be a hand-held telephone, a laptop computer equipped with a mobile broadband adapter, or any other device. It connects to the base station Node B/eNodeB as specified in the ETSI 125/136-series and 3GPP 25/36-series of specifications. It roughly corresponds to the mobile station (MS) in GSM systems. The radio interface between the UE and the Node B is called ''Uu''. Functionality UE handles the following tasks towards the core network: * Mobility management * Call control * Session management * Identity management The corresponding protocols are transmitted transparently via a Node B, that is, Node B does not change, use or understand the information. These protocols are also referred to as ''Non Access Stratum Non-access stratum (NAS) is a functional layer in the NR, LTE, UMTS and GSM wireless tele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture and, therefore, mobile telephones are called ''cellular telephones'' or ''cell phones'' in North America. In addition to telephony, digital mobile phones ( 2G) support a variety of other services, such as text messaging, multimedia messagIng, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, video games and digital photography. Mobile phones offering only those capabilities are known as fea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
