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Fountain Code
In coding theory, fountain codes (also known as rateless erasure codes) are a class of erasure codes with the property that a potentially limitless sequence of encoding symbols can be generated from a given set of source symbols such that the original source symbols can ideally be recovered from any subset of the encoding symbols of size equal to or only slightly larger than the number of source symbols. The term ''fountain'' or ''rateless'' refers to the fact that these codes do not exhibit a fixed code rate. A fountain code is optimal if the original ''k'' source symbols can be recovered from any ''k'' successfully received encoding symbols (i.e., excluding those that were erased). Fountain codes are known that have efficient encoding and decoding algorithms and that allow the recovery of the original ''k'' source symbols from any ''k’'' of the encoding symbols with high probability, where ''k’'' is just slightly larger than ''k''. LT codes were the first practical realizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coding Theory
Coding theory is the study of the properties of codes and their respective fitness for specific applications. Codes are used for data compression, cryptography, error detection and correction, data transmission and computer data storage, data storage. Codes are studied by various scientific disciplines—such as information theory, electrical engineering, mathematics, linguistics, and computer science—for the purpose of designing efficient and reliable data transmission methods. This typically involves the removal of redundancy and the correction or detection of errors in the transmitted data. There are four types of coding: # Data compression (or ''source coding'') # Error detection and correction, Error control (or ''channel coding'') # Cryptography, Cryptographic coding # Line code, Line coding Data compression attempts to remove unwanted redundancy from the data from a source in order to transmit it more efficiently. For example, DEFLATE data compression makes files small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raptor Code
In computer science, Raptor codes (''rapid tornado''; see Tornado codes) are the first known class of fountain codes with linear time encoding and decoding. They were invented by Amin Shokrollahi in 2000/2001 and were first published in 2004 as an extended abstract. Raptor codes are a significant theoretical and practical improvement over LT codes, which were the first practical class of fountain codes. Raptor codes, as with fountain codes in general, encode a given source block of data consisting of a number ''k'' of equal size source symbols into a potentially limitless sequence of encoding symbols such that reception of any ''k'' or more encoding symbols allows the source block to be recovered with some non-zero probability. The probability that the source block can be recovered increases with the number of encoding symbols received above ''k'' becoming very close to 1, once the number of received encoding symbols is only very slightly larger than ''k''. For example, with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Online Codes
In computer science, online codes are an example of rateless erasure codes. These codes can encode a message into a number of symbols such that knowledge of any fraction of them allows one to recover the original message (with high probability). ''Rateless'' codes produce an arbitrarily large number of symbols which can be broadcast until the receivers have enough symbols. The online encoding algorithm consists of several phases. First the message is split into ''n'' fixed size message blocks. Then the ''outer encoding'' is an erasure code which produces auxiliary blocks that are appended to the message blocks to form a composite message. From this the inner encoding generates check blocks. Upon receiving a certain number of check blocks some fraction of the composite message can be recovered. Once enough has been recovered the outer decoding can be used to recover the original message. Detailed discussion Online codes are parameterised by the block size and two scalars, ''q'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secret Splitting
Secret sharing (also called secret splitting) refers to methods for distributing a secret among a group, in such a way that no individual holds any intelligible information about the secret, but when a sufficient number of individuals combine their 'shares', the secret may be reconstructed. Whereas ''insecure'' secret sharing allows an attacker to gain more information with each share, ''secure'' secret sharing is 'all or nothing' (where 'all' means the necessary number of shares). In one type of secret sharing scheme there is one ''dealer'' and ''n'' ''players''. The dealer gives a share of the secret to the players, but only when specific conditions are fulfilled will the players be able to reconstruct the secret from their shares. The dealer accomplishes this by giving each player a share in such a way that any group of ''t'' (for ''threshold'') or more players can together reconstruct the secret but no group of fewer than ''t'' players can. Such a system is called a -threshol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megabyte
The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes of information. This definition has been incorporated into the International System of Quantities. In the computer and information technology fields, other definitions have been used that arose for historical reasons of convenience. A common usage has been to designate one megabyte as (220 B), a quantity that conveniently expresses the binary architecture of digital computer memory. Standards bodies have deprecated this binary usage of the mega- prefix in favor of a new set of binary prefixes, by means of which the quantity 220 B is named mebibyte (symbol MiB). Definitions The unit megabyte is commonly used for 10002 (one million) bytes or 10242 bytes. The interpretation of using base 1024 originated as technical jargon for the byte m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRC Press
The CRC Press, LLC is an American publishing group that specializes in producing technical books. Many of their books relate to engineering, science and mathematics. Their scope also includes books on business, forensics and information technology. CRC Press is now a division of Taylor & Francis, itself a subsidiary of Informa. History The CRC Press was founded as the Chemical Rubber Company (CRC) in 1903 by brothers Arthur, Leo and Emanuel Friedman in Cleveland, Ohio, based on an earlier enterprise by Arthur, who had begun selling rubber laboratory aprons in 1900. The company gradually expanded to include sales of laboratory equipment to chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...s. In 1913 the CRC offered a short (116-page) manual called the ''Rubber Handboo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DVB-IPTV
IP over DVB implies that Internet Protocol datagrams are distributed using some digital television system, for example DVB-H, DVB-SH, DVB-T, DVB-S, DVB-C or their successors like DVB-T2, DVB-S2, and DVB-C2. This may take the form of IP over MPEG, where the datagrams are transferred over the MPEG transport stream, or the datagrams may be carried in the DVB baseband frames directly, as in GSE. Application examples * Data broadcast ( datacast), for example a data carousel sending programme information and media over and over again. * IP multicast, for sending media efficiently to a limited group of subscribing users, using only the transmitter towers where users for the moment are situated. * interactive TV services * To provide internet access by utilizing the DVB system as a broadband downlink, in combination with some narrow-band duplex system. Examples: ** Satellite Internet access, e.g. to buildings in the countryside, using a telephone modem as the back-channel ** Broadband ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Video Broadcasting
Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU). Transmission DVB systems distribute data using a variety of approaches, including: * Satellite: DVB-S, DVB-DSNG, DVB-S2, DVB-S2X and DVB-SH ** DVB-SMATV for distribution via SMATV * Cable: DVB-C, DVB-C2 * Terrestrial television: DVB-T, DVB-T2 ** Digital terrestrial television for handhelds: DVB-H, DVB-SH * Microwave: using DTT ( DVB-MT), the MMDS ( DVB-MC), and/or MVDS standards ( DVB-MS) These standards define the physical layer and data link layer of the distribution system. Devices interact with the physical layer via a synchronous parallel interface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Protocol Datacasting
Datacasting (data broadcasting) is the transmission of data over a wide area using radio waves. It typically refers to supplemental information sent by television stations alongside digital terrestrial television (DTT) signals. However, datacasting can also be applied to digital data signals carried on analog TV or radio broadcasts. Overview Datacasting often provides a variety of information such as news, weather forecasting, traffic reporting, stock market updates, and other data that may or may not relate to the broadcast programs. It can also include interactive elements like gaming, shopping, or educational content. An electronic program guide is typically included, though this feature is sometimes considered inherent to the digital broadcast standard. The ATSC, DVB, and ISDB standards support broadband datacasting via Digital Terrestrial Television (DTT), although the specifics of implementation are not always defined. For analog TV, moderate and low bandwidths are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DVB-H
DVB-H (digital video broadcasting - handheld) is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification (EN 302 304) can be downloaded from the official DVB-H website. For a few months from March 2008, DVB-H was officially endorsed by the European Union as the "preferred technology for terrestrial mobile broadcasting". The major competitors of this technology were Qualcomm's MediaFLO system, the 3G cellular system based MBMS mobile-TV standard, and the ATSC-M/H format in the U.S. , the recently introduced DVB-SH (Satellite to Handhelds) and anticipated DVB-NGH (Next Generation Handheld) in the future were possible enhancements to DVB-H, providing improved spectral efficiency and better modulation flexibility. DVB-H struggled against resistance from network operators to include the technology in their subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MBMS
Multimedia Broadcast Multicast Services (MBMS) is a point-to-multipoint interface specification for existing 3GPP cellular networks, which is designed to provide efficient delivery of broadcast and multicast services, both within a cell as well as within the core network. For broadcast transmission across multiple cells, it defines transmission via single-frequency network configurations. The specification is referred to as Evolved Multimedia Broadcast Multicast Services (eMBMS) when transmissions are delivered through an LTE (Long Term Evolution) network. eMBMS is also known as LTE Broadcast.GSALTE Broadcast (eMBMS) Market Update – January 2019(retrieved 7 January 2019) Target applications include mobile TV and radio broadcasting, live streaming video services, as well as file delivery and emergency alerts. Questions remain whether the technology is an optimization tool for the operator or if an operator can generate new revenues with it. Several studies have been published o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3GPP
The 3rd Generation Partnership Project (3GPP) is an umbrella term for a number of standards organizations which develop protocols for mobile telecommunications. Its best known work is the development and maintenance of: * GSM and related 2G and 2.5G standards, including GPRS and EDGE * UMTS and related 3G standards, including HSPA and HSPA+ * LTE and related 4G standards, including LTE Advanced and LTE Advanced Pro * 5G NR and related 5G standards, including 5G-Advanced * An evolved IP Multimedia Subsystem (IMS) developed in an access independent manner 3GPP is a consortium with seven national or regional telecommunication standards organizations as primary members ("organizational partners") and a variety of other organizations as associate members ("market representation partners"). The 3GPP organizes its work into three different streams: Radio Access Networks, Services and Systems Aspects, and Core Network and Terminals. The project was established in Decembe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
