Parallel communication

Parallel communication

In telecommunication and computer science, parallel communication is a method of sending several data signals simultaneously over a communication link "(comprising of several wired channels in parallel)" at one time. It contrasts with serial communication; this distinction is one way of characterizing a communications link.

The basic difference between a parallel and a serial communication channel is the number of distinct wires or strands at the physical layer used for simultaneous transmission from a device. Parallel communication implies more than one such wire/strand, in addition to a ground connection.

Examples of parallel communication systems

* Computer peripheral buses: ISA, ATA, SCSI, PCI and Front side bus, and the once-ubiquitous IEEE-1284 / Centronics "printer port"
* Laboratory Instrumentation bus IEEE-488(see more examples at Computer bus)

Comparison with serial links

Before the development of high-speed serial technologies, the choice of parallel links over serial links was driven by these factors:

* Speed: Superficially, the speed of a parallel data link is equal to the number of bits sent at one time times the bit rate of each individual path; doubling the number of bits sent at once doubles the data rate (see Parallel transmission). In practice, skew reduces the speed of every link to the slowest of all of the links.

* Cable length: Crosstalk creates interference between the parallel lines, and the effect worsens with the length of the communication link. This places an upper limit on the length of a parallel data connection that is usually shorter than a serial connection.

* Complexity: Parallel data links are easily implemented in hardware, making them a logical choice. Creating a parallel port in a computer system is relatively simple, requiring only a latch to copy data onto a data bus. In contrast, most serial communication must first be converted back into parallel form by a Universal asynchronous receiver transmitter before they may be directly connected to a data bus.

The decreasing cost of integrated circuits, combined with greater consumer demand for speed and cable length, has led to parallel communication links becoming deprecated in favor of serial links; for example, IEEE 1284 printer ports vs. USB, Advanced Technology Attachment vs. Serial ATA, SCSI vs. FireWire.

On the other hand, there has been a resurgence of parallel data links in RF communication. Rather than transmitting one bit at a time (as in Morse code and BPSK), well-known techniques such as PSM, PAM, and Multiple-input multiple-output communication send a few bits in parallel. (Each such group of bits is called a "symbol"). Such techniques can be extended to send an entire byte at once (256-QAM). More recently techniques such as OFDM have been used in Asymmetric Digital Subscriber Line to transmit over 224 bits in parallel, and in DVB-T to transmit over 6048 bits in parallel.

ee also

*Serial communication.

we love ron wates


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Parallel — may refer to: Mathematics and science * Parallel (geometry) * Parallel (latitude), an imaginary east west line circling a globe Proper name * Parallel (manga), a shōnen manga by Toshihiko Kobayashi * Parallel (video), a video album by R.E.M. *… …   Wikipedia

  • Parallel adoption — is a method for transferring between an old (IT) system to a target (IT) system in an organization. In order to reduce risk, the old and new system run simultaneously for some period of time after which, if the criteria for the new system are met …   Wikipedia

  • Parallel mesh generation — in numerical analysis is a new research area between the boundaries of two scientific computing disciplines: computational geometry and parallel computingNikos Chrisochoides, Parallel Mesh Generation, Chapter in Numerical Solution of Partial… …   Wikipedia

  • Parallel ATA — ATA connector on the right, with two motherboard ATA sockets on the left. Type …   Wikipedia

  • Parallel slowdown — is a phenomenon in parallel computing where parallelization of a parallel computer program beyond a certain point causes the program to run slower (take more time to run to completion). Parallel slowdown is typically the result of a… …   Wikipedia

  • Communication-based train control — (CBTC) is an automated control system for railways that ensures the safe operation of rail vehicles using data communication between various control entities that make up the system.CBTC is a modern successor of the traditional railway signaling… …   Wikipedia

  • Parallel virtual machine — (PVM) est une bibliothèque de communication (langages C et Fortran) pour machines parallèles et réseau d ordinateurs (locaux ou distants, éventuellement hétérogènes). Il permet à un réseau d ordinateurs d apparaître comme un seul ordinateur,… …   Wikipédia en Français

  • Parallel Virtual Machine — (PVM) est une bibliothèque de communication (langages C et Fortran) pour machines parallèles et réseau d ordinateurs (locaux ou distants, éventuellement hétérogènes). Il permet à un réseau d ordinateurs d apparaître comme un seul ordinateur,… …   Wikipédia en Français

  • Parallel computing — Programming paradigms Agent oriented Automata based Component based Flow based Pipelined Concatenative Concurrent computing …   Wikipedia

  • Communication — For the term used in the game of bridge, see Glossary of contract bridge terms # communication. Communication is the activity of conveying meaningful information. Communication requires a sender, a message, and an intended recipient, although the …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”