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Wireless Ad-hoc Network
A wireless ad hoc network (WANET) or mobile ad hoc network (MANET) is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre-existing infrastructure, such as routers or wireless access points. Instead, each node participates in routing by forwarding data for other nodes. The determination of which nodes forward data is made dynamically on the basis of network connectivity and the routing algorithm in use. Such wireless networks lack the complexities of infrastructure setup and administration, enabling devices to create and join networks "on the fly". Each device in a MANET is free to move independently in any direction, and will therefore change its links to other devices frequently. Each must forward traffic unrelated to its own use, and therefore be a router. The primary challenge in building a MANET is equipping each device to continuously maintain the information required to properly route traffic. This becomes harder as the scal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Network
A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking allows homes, telecommunications networks, and business installations to avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Admin telecommunications networks are generally implemented and administered using radio communication. This implementation takes place at the physical level (layer) of the OSI model network structure. Examples of wireless networks include cell phone networks, WLAN, wireless local area networks (WLANs), wireless sensor networks, satellite communication networks, and terrestrial microwave networks. History Wireless networks The first professional wireless network was developed under the brand ALOHAnet in 1969 at the University of Hawaii and became operational in June 1971. The first commercial wireless network was the WaveLAN product family, developed by NCR Corpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Radio
In digital radio, packet radio is the application of packet switching techniques to digital radio communications. Packet radio uses a packet switching Communication protocol, protocol as opposed to circuit switching or message switching protocols to transmit digital data via a radio communication link. Packet radio is frequently used by amateur radio operators. The AX.25 (Amateur X.25) protocol was derived from the X.25 data link layer protocol and adapted for amateur radio use. Every AX.25 packet includes the sender's amateur radio callsign, which satisfies the US FCC requirements for amateur radio station identification. AX.25 allows other stations to automatically repeat packets to extend the range of transmissions. It is possible for any packet station to act as a digipeater, linking distant stations with each other through ad hoc networks. This makes packet radio especially useful for emergency communications. Packet radio can be used in mobile communications. Some mobile pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chai Keong Toh
Chai Keong Toh (born 1965) is a Singaporean computer scientist, engineer, industry director, former VP/CTO and university professor. He is currently a Senior Fellow at the University of California Berkeley, USA. He was formerly Assistant Chief Executive (Engineering & Technology) of Infocomm Development Authority (IDA) Singapore. He has performed research on wireless ad hoc networks, mobile computing, Internet Protocols, and multimedia for over two decades. Toh's current research is focused on Internet-of-Things (IoT), architectures, platforms, and applications behind the development of smart cities. Early life Born in Singapore, Toh studied in Singapore Polytechnic and then received his university education in the United Kingdom. He subsequently moved to live and work in the United States. He studied at King's College, Cambridge under a Cambridge Commonwealth Trust Scholarship, and received his Ph.D. in computer science from University of Cambridge, UK in 1996 and his undergr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hop (networking)
In wired computer networking a hop occurs when a packet is passed from one network segment to the next. Data packets pass through routers as they travel between source and destination. The hop count refers to the number of network devices through which data passes from source to destination (depending on routing protocol, this may include the source/destination, that is, the first hop is counted as hop 0 or hop 1). Since store and forward and other latencies are incurred through each hop, a large number of hops between source and destination implies lower real-time performance. Hop count In wired networks, the hop count refers to the number of networks or network devices through which data passes between source and destination (depending on routing protocol, this may include the source/destination, that is, the first hop is counted as hop 0 or hop 1). Thus, hop count is a rough measure of distance between two hosts. For a routing protocol using 1-origin hop counts (such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Protocols
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics, and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both. Communicating systems use well-defined formats for exchanging various messages. Each message has an exact meaning intended to elicit a response from a range of possible responses predetermined for that particular situation. The specified behavior is typically independent of how it is to be implemented. Communication protocols have to be agreed upon by the parties involved. To reach an agreement, a protocol may be developed into a technical standard. A programming language describes the same for computations, so there is a close analogy between protocols and programming languages: ''protocols are to communicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEEE 802
IEEE 802 is a family of Institute of Electrical and Electronics Engineers (IEEE) standards for local area networks (LANs), personal area networks (PANs), and metropolitan area networks (MANs). The IEEE 802 LAN/MAN Standards Committee (LMSC) maintains these standards. The IEEE 802 family of standards has had twenty-four members, numbered 802.1 through 802.24, with a working group of the LMSC devoted to each. However, not all of these working groups are currently active. The IEEE 802 standards are restricted to computer networks carrying variable-size packets, unlike cell relay networks, for example, in which data is transmitted in short, uniformly sized units called cells. Isochronous signal networks, in which data is transmitted as a steady stream of octet (computing), octets, or groups of octets, at regular time intervals, are also outside the scope of the IEEE 802 standards. The number 802 has no significance: it was simply the next number in the sequence that the IEEE used fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laptop
A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a Clamshell design, clamshell form factor (design), form factor with a flat-panel computer screen, screen on the inside of the upper lid and an alphanumeric keyboard and pointing device on the inside of the lower lid. Most of the computer's internal hardware is in the lower part, under the keyboard, although many modern laptops have a built-in webcam at the top of the screen, and some even feature a touchscreen display. In most cases, unlike tablet computers which run on mobile operating systems, laptops tend to run on desktop operating systems, which were originally developed for desktop computers. Laptops are used in a variety of settings, such as at work (especially on business trips), in education, for PC game, playing games, Content creation, content creating, web browser, web browsing, for personal multimedia, and for general P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Personal Computer
A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC game, gaming. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician. Unlike large, costly minicomputers and mainframes, time-sharing by many people at the same time is not used with personal computers. The term home computer has also been used, primarily in the late 1970s and 1980s. The advent of personal computers and the concurrent Digital Revolution have significantly affected the lives of people. Institutional or corporate computer owners in the 1960s had to write their own programs to do any useful work with computers. While personal computer users may develop their applications, usually these systems run commercial software, free-of-charge software ("freeware"), which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near-term Digital Radio
The Near-term digital radio (NTDR) program provided a prototype mobile ad hoc network (MANET) radio system to the United States Army, starting in the 1990s. The MANET protocols were provided by Bolt, Beranek and Newman; the radio hardware was supplied by ITT. These systems have been fielded by the United Kingdom as the High-capacity data radio (HCDR) and by the Israelis as the Israeli data radio. They have also been purchased by a number of other countries for experimentation. The NTDR protocols consist of two components: clustering and routing. The clustering algorithms dynamically organize a given network into cluster heads and cluster members. The cluster heads create a backbone; the cluster members use the services of this backbone to send and receive packets. The cluster heads use a link-state routing algorithm to maintain the integrity of their backbone and to track the locations of cluster members. The NTDR routers also use a variant of Open Shortest Path First Op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SURAN
The Survivable Radio Network (SURAN) project was sponsored by DARPA in the 1980s to develop a set of mobile ad hoc network (MANET) radio-routers, then known as "packet radios". It was a follow-on to DARPA's earlier PRNET project. The program began in 1983 with the following goals: * develop a small, low-cost, low-power radio that would support more sophisticated packet radio protocols than the DARPA Packet Radio project from the 1970s * develop and demonstrate algorithms that could scale to tens of thousands of nodes * develop and demonstrate techniques for robust and survivable packet networking in sophisticated electronic attacks. A follow-on program in 1987, the Low-cost Packet Radio (LPR), attempted further innovations in mobile networking protocols, with design goals including: * management of radio spreading codes for security, and increasing capacity * new queue management and forwarding techniques for spread spectrum channels * scalability based on dynamic clustering BB ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ray Tomlinson
Raymond Samuel Tomlinson (April 23, 1941 – March 5, 2016) was an American computer scientist who implemented the first email program on the ARPANET system, the precursor to the Internet, in 1971; it was the first system able to send mail between users on different hosts connected to ARPANET. Previously, mail could be sent only to others who used the same computer. To achieve this, he used the @ sign to separate the username from the name of their machine, a scheme which has been used in email addresses ever since. The Internet Hall of Fame in its account of his work commented "Tomlinson's email program brought about a complete revolution, fundamentally changing the way people communicate." He is credited with the invention of the TCP three-way handshake which underlies HTTP and many other key Internet protocols. Early life and education Tomlinson was born in Amsterdam, New York, but his family soon moved to the small, unincorporated village of Vail Mills, Broadalbin, New ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Association For Computing Machinery
The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a non-profit professional membership group, reporting nearly 110,000 student and professional members . Its headquarters are in New York City. The ACM is an umbrella organization for academic and scholarly interests in computer science (informatics). Its motto is "Advancing Computing as a Science & Profession". History In 1947, a notice was sent to various people: On January 10, 1947, at the Symposium on Large-Scale Digital Calculating Machinery at the Harvard computation Laboratory, Professor Samuel H. Caldwell of Massachusetts Institute of Technology spoke of the need for an association of those interested in computing machinery, and of the need for communication between them. ..After making some inquiries during May and June, we believe there is ample interest to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
