Asynchronous communication

In telecommunications, asynchronous communication is transmission of data, generally without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream.^[1] Any timing required to recover data from the communication symbols is encoded within the symbols.

The most significant aspect of asynchronous communications is that data is not transmitted at regular intervals, thus making possible

variable bit rate, and that the transmitter and receiver clock generators do not have to be exactly synchronized all the time. In asynchronous transmission, data is sent one byte at a time and each byte is preceded by start and stop bits

.

Physical layer

In

V.2

.

Data link layer and higher

Asynchronous communication at the

SONET/SDH

.

The packets may be encapsulated in a

PPP and USB

protocols.

Application layer

An asynchronous communication service or application does not require a constant bit rate.

video conferencing

.

Electronically mediated communication

Electronically mediated communication often happens asynchronously in that the participants do not communicate concurrently. Examples include email^[3] and

bulletin-board systems

, where participants send or post messages at different times than they read them. The term "asynchronous communication" acquired currency in the field of online learning, where teachers and students often exchange information asynchronously instead of synchronously (that is, simultaneously), as they would in face-to-face or in telephone conversations.

References

^ Beal, Vangie (September 1, 1996). "asynchronous". Webopedia. Archived from the original on 30 April 2011. Retrieved 2011-04-27. The term asynchronous is usually used to describe communications in which data can be transmitted intermittently rather than in a steady stream.
^ Hargrave, Frank (2001). Hargrave's Communication Dictionary. Wiley.
^ Calladine, Richard (2006). "A taxonomy of learning technologies: simplifying online learning for learners, professors, and designers". In Khosrowpour, Mehdi (ed.). Emerging Trends and Challenges in Information Technology Management: 2006 Information Resources Management Association International Conference, Washington, DC, USA, May 21-24, 2006. Vol. 1. Idea Group Inc (IGI). p. 249.
ISBN 9781599040196
. Retrieved 2014-09-03. Email and Internet Chat provide a good example of the difference between synchronous and asynchronous technologies. Email is generally responded to at the discretion of the user and hence is described as asynchronous. However, when in a Chat session each participant knows that the others are waiting for their responses. The resulting "conversations" are synchronous [...]

[1] Beal, Vangie (September 1, 1996). "asynchronous". Webopedia. Archived from the original on 30 April 2011. Retrieved 2011-04-27. The term asynchronous is usually used to describe communications in which data can be transmitted intermittently rather than in a steady stream.

[2] Hargrave, Frank (2001). Hargrave's Communication Dictionary. Wiley.

[3] Calladine, Richard (2006). "A taxonomy of learning technologies: simplifying online learning for learners, professors, and designers". In Khosrowpour, Mehdi (ed.). Emerging Trends and Challenges in Information Technology Management: 2006 Information Resources Management Association International Conference, Washington, DC, USA, May 21-24, 2006. Vol. 1. Idea Group Inc (IGI). p. 249.
ISBN 9781599040196
. Retrieved 2014-09-03. Email and Internet Chat provide a good example of the difference between synchronous and asynchronous technologies. Email is generally responded to at the discretion of the user and hence is described as asynchronous. However, when in a Chat session each participant knows that the others are waiting for their responses. The resulting "conversations" are synchronous [...]

[1]

[3]

Physical layer

Data link layer and higher

Application layer

Electronically mediated communication

See also

References