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Functions of the MAC Layer

By Dinesh Thakur

The MAC layer is the “Brain” of WiFi. The first version of 802.11 (the 802.11 legacy published in 1997), defined the MAC layer by incorporating a number of features crucial, such as sharing of speech among users, the terms of network connection, error control or security. [Read more…] about Functions of the MAC Layer

Applications of Wifi

By Dinesh Thakur

The extension of the corporate network

Although there are a multitude of applications in WiFi technology, it is clear as its primary target is the corporate network. As we have seen, the WiFi was designed for a wireless version of Ethernet and the latter is found in almost all businesses. In most cases, a company that decides be equipped with a WiFi network already has a wired Ethernet network. It is therefore generally build a wireless extension to an existing wired network. [Read more…] about Applications of Wifi

What is Error Detection and Correction?

By Dinesh Thakur

The application of methods derived from INFORMATION THEORY to the detection and correcting of errors in DIGITAL data streams. Error correction is of the utmost importance in most areas of computing and communications technology. For example: Internet’s TCP protocol provides error detection, CD-ROMS devote around 14% of their total data capacity to redundant error correction information (and music CDS only a little less), and modem speeds above 28 kilobits per second would be impossible over public telephone lines without error correcting PROTOCOLS such as v.90. [Read more…] about What is Error Detection and Correction?

What is DSL (Digital Subscriber Line)?

By Dinesh Thakur

(xDSL) A whole class of digital telecommunication technologies that can offer BROADBAND data rates, up to 50 megabits per second (Mbps), over the existing copper wires of the analogue public telephone system. By employing advanced modulation schemes, xDSL technologies support Internet or other data access simultaneously with voice telephone calls. In the meta-acronym xDSL, the x stands for the first letter of any of the individual acronyms used for these technologies: ADSL, HDSL, SDSL and VDSL. [Read more…] about What is DSL (Digital Subscriber Line)?

What is Transfer rate?

By Dinesh Thakur

The transfer rate, or “data rate” refers to the speed with which data is transferred from its source to its destination, such as from one computer to another over a network, or from the computer to the disk drive. It’s measured like we would measure any rate of speed-in units of information per the unit of time, like miles per hour. On a computer you may hear transfer rates expressed in terms like bits per second, megabytes per second, or characters per second.

What is Parity bit?

By Dinesh Thakur

Parity is a form of “error checking” where the computer checks to see if all the data it was supposed to get really did come through. You will most likely be confronted with parity when you use a telecommunications package to communicate through your modem. In fact, that’s probably why you’re reading this. The dialog box where you can set the serial port settings always wants to know the parity. The default setting is probably the safest thing to use if you don’t know a reason to change it. [Read more…] about What is Parity bit?

What is half duplex?

By Dinesh Thakur

Half duplex means data can be relayed in only one direction at a time. Two-way transmission is possible, but the transmissions must be alternate. A walkie-talkie is half duplex-when one person is speaking, she cannot also listen A telephone is full duplex-information can go both ways simultaneously; both ends can talk and hear all the time-so does a modem. [Read more…] about What is half duplex?

What is EtherTalk?

By Dinesh Thakur

EtherTalk is Apple Computer software that allows the Macintosh to hook into Ethernet networks. To use EtherTalk and Ethernet, the Mac must have the Ethernet interface card installed inside the computer.

 When you see a computer ad that says something like “8/80E,” the E means the computer includes the Ethernet interface card. (The numbers tell you how many megabytes of RAM and hard disk space.)

What is email?

By Dinesh Thakur

E-mail is short for electronic mail, mail you can send or receive directly on your computer. Yes, with e-mail people can actually write you letters and send them to your computer, and you can turn on your computer and go pick up your mail whenever it’s convenient. Many a love affair has begun through e-mail. I know. It’s really fun, too. And useful, of course. E-mail can be a verb too, as in “I e-mailed my lover a letter from Lhasa.” [Read more…] about What is email?

What is a Distributed Computing System? – Definition

By Dinesh Thakur

A Distributed computing is a model of computation that is firmly related to Distributed Systems, refers to as multiple computer systems located at different places linked together over a network and use to solve higher level computation without having to use an expensive supercomputer. Distributed system is called, When collection of various computers seems a single coherent system to its client, then it is called distributed system.
 [Read more…] about What is a Distributed Computing System? – Definition

What is Communications?

By Dinesh Thakur

From the early 1900s until now, long distance communication has primarily been in the form of the telephone line. Now telephone lines are being used for more than the transmission of voice; they are also used for the transmission of computer data. There are many reasons why someone might want to transfer data between one PC and another using phone lines. [Read more…] about What is Communications?

What is CTS?

By Dinesh Thakur

In the world of asynchronous communication (over Mac or PC serial ports), CTS stands for clear to send. When a computer needs to communicate with an outside device physically connected to it (peripheral), the two of them have to go through this preamble of making sure each of them is ready to hear what the other has to say, and confirm that they are going to be speaking the same language. Somewhere near the beginning of this preamble, one device will send an RTS (Request To Send) message. The receiving device will then reply with a CTS message “Yes, I’m now ready for anything you want to send me.” I know, the whole thing sounds like you may be sitting there drumming your fingers on your desk, waiting for these flipping machines to get done with their senseless checklist. Relax. Like most processes done by a computer, this one takes less than a millisecond.

What is CRC?

By Dinesh Thakur

CRC (cyclical redundancy checking) is a rather sophisticated error checking routine used to assure that two communicating computers are really getting the correct data. There are a whole bunch of these error correction and checking methods out there, but they all have pretty much the same objective: making sure that no data is lost or misinterpreted when two computers are exchanging information over the phone lines (through a modem, of course).

What is CompuServe?

By Dinesh Thakur

CompuServe (whose formal name is CompuServe Information Services, or CIS for short and sometimes CI$ for a statement) is a commercial online service that you can access through your modem. It has an incredible array of forums (sections devoted to particular interests), conferences, facilities for uploading and downloading information, and all the other benefits a powerful online service offers. [Read more…] about What is CompuServe?

What is Broadcast Network?

By Dinesh Thakur

Broadcast: Any form of communication in which a single sender transmits messages to many receivers at once, the most familiar examples being the television and public radio systems. The opposite of broadcast is POINT-TO-POINT or narrowcast communication, between just a single transmitter and a single receiver – a telephone conversation for example. When such a multiple connection is made via a network cable as opposed to wireless, such communication is often called MULTIPOINT, as opposed to a point-to-point or UNICAST. Communication channel is shared by all the machines on the network in broadcast network.
 [Read more…] about What is Broadcast Network?

What is Broadband ISDN?

By Dinesh Thakur

Broadband ISDN (BISON) The next-generation of ISDN technology, with promised bandwidths from 150 megabits per second upward, sufficient to carry video-phone calls and movies. BISON will be carried over FIBRE-OPTIC cabling rather than wire, and the underlying transport protocol will be ASYNCHRONOUS TRANSFER MODE. Different implementations are planned in the USA, which will employ YNCHRONOUS OPTICAL NETWORK and Europe, which will use SYNCHRONOUS DIGITAL HIERARCHY.

What is Bit Error?

By Dinesh Thakur

Bit Error: An error in a single BIT within a BYTE or WORD of data transmitted over a noisy channel: for example if the byte sent was 11111111 then a received value of 11111101 would represent a bit error in the second bit. There are well-known ERROR DETECTION AND CORRECTION algorithms that can correct one or more such bit errors, given some extra, redundant information, and these techniques are widely applied in the mechanisms of HARDDISK and CD-ROM drives, as well as in telecommunication systems.

What is transmission Baseband?

By Dinesh Thakur

Let us examine the transmission technique that is to say how a transmitter can send a signal that the receiver will recognize as a 1 or a 0.

A communications medium over which signals are sent with no shifting of their frequency, so that only one signal can be carried at a time: the original ETHERNET and the ANALOGUE public phone system are both baseband media. The alternative is to alter the frequency and phase of signals to permit many to share one channel. [Read more…] about What is transmission Baseband?

What is bps (bits per second)?

By Dinesh Thakur

The acronym bps stands for bits per second, which is a measurement of how fast information (data) travels between two devices. When two modems converse via the telephone line, the speed of modem communications is measured in bps. (When people talk about modems, they often use the word “baud” to mean the same thing as bps, though technically the two terms are not synonymous. [Read more…] about What is bps (bits per second)?

What is baud rate?

By Dinesh Thakur

baud, baud rate A baud is the number of signaling elements per second sent by a communications device such as a modem, In theory, a modem with a high baud rate means fast transmission. The baud rate is therefore equal to the bit rate only if each signal element represents one bit of information. [Read more…] about What is baud rate?

What is BBS (Bulletin Board System)?

By Dinesh Thakur

BBS (Bulletin Board System): A single computer running special communications software that acts as a kind of electronic bulletin board. That allows remote users to dial in via a public telephone line to exchange messages and chat with one another. which is a service usually set up by an organization or a club to provide or exchange information. A BBS allows multiple people to use it at the same time in order to exchange ideas, offer help with software problems, and converse (through typed conversations) with other users currently connected to the BBS. You access the BBS through your modem , a device that transmits data through ordinary telephone lines. While connected to a BBS, a user can share information with other computer users, leave messages, and upload and download programs. One popular BBS is the Boston Computer Exchange, a place where members can buy, sell, or trade computers. Pay-for-use information services, such as CompuServe, Prodigy, and Internet are like BBS, but much larger. There are thousands of other BBSs across the globe offering a variety of topics and interests ranging from software support to dating services. To communicate with other computers, a modem is necessary. [Read more…] about What is BBS (Bulletin Board System)?

What is Audio Compression?

By Dinesh Thakur

The application of FILE COMPRESSION algorithms to digital sound files to reduce their required storage space and hence their download time over low-bandwidth communication links such as the Internet. Lossless audio compression can be achieved using exactly the same algorithms as for any other kind of digital data. However, as with visual images, compression is most effective when some quality is sacrificed (so-called LOSSY compression methods), and the most widely used compressed formats such as MP3 and REAL AUDIO use such methods to achieve compression ratios on the order of 60:1 to 80:1. [Read more…] about What is Audio Compression?

What is ATM Adaptation Layer (AAL)?

By Dinesh Thakur

AAL (ATM Adaptation Layer) is a third example message level protocol. A software layer that accepts user data, such as digitized voice, video or computer data, and converts to and from cells for transmission over an ASYNCHRONOUS TRANSFER MODE network. AAL software mostly runs at the end-points of a connection, though in a few circumstances AAL software is run inside an ATM switch. AAL includes facilities to carry traffic that uses other network protocols, such as TCP/IP, over ATM. [Read more…] about What is ATM Adaptation Layer (AAL)?

What is ATM (Asynchronous Transfer Mode)? Definition

By Dinesh Thakur

Definition: Asynchronous Transfer Mode (ATM) also called cell relay (transferring data in cells of a fixed size) that is operates at the data link layer (Layer 2) of OSI Model over fiber or twisted-pair cable, a high-speed switched network technology based on ITU-T Broadband Integrated Services Digital Network (B-ISDN) standard, developed by the telecommunications industry to implement the next generation network. ATM was designed for use in WANs such as the public telephone system and corporate data networks, though it has also been applied to create super-fast LANs. [Read more…] about What is ATM (Asynchronous Transfer Mode)? Definition