Asynchronous or statistical time division multiplexing, Computer Networking

Asynchronous or Statistical Time Division Multiplexing

As we  have seen  synchronous  TDM does not  guarantee that the full capacity of a link in sued. In fact it is more likely  that only  a portion of the  time slots are in use at a given  instant. Because  the time  slots  are reassigned and  fixed whenever a connected device is not  transmitting, the  corresponding  slot is empty and that much   capacity of the path  is wasted. For  example imagine that we have multiplexed the output of 20 identical computer onto a single line. Suing synchronous TDM the speed  of that line must be at  least 20 times the speed of each input line. But  what  if only 10 computers  are in use at a time ? half of the capacity  of the line  is wasted.

Statistical  time  division  multiplexing is designed to avoid this type of waste. As with  the term  synchronous. The term  asynchronous means some  things   different  in multiplexing  that it  means  in other  areas of data communications. Here it  flexible  or not  fixed.

Like synchronous TDM asynchronous TDM allows  a number of lower  speed  input  lines  to be  multiplexed  to a single  higher speed  line. Unlike  synchronous  TDM however in asynchronous TDM the total  speed of the input  can be greater than  the capacity  of the path. In a synchronous systems if we have in  input  lines. The frame contains a fixed number of a least m time  slots. In  an asynchronous systems. If  we have  n input line the  frame contains no more  than  m slots with m less than n. In  this way asynchronous TDM supports  the same  number of input lines as synchronous TDM with a lower capacity  link or given the same  link. Asynchronous TDM can support more  devices  than  synchronous TDM.

1558_Asynchronous or Statistical Time Division Multiplexing.gif

figure Asynchronous TDM

The number  of time  slots in an asynchronous TDM fame is based on a statistical analysis of the number  of input lines that are likely to be transmitting at any given  time. Rather than being reassigned each slot  is available to any  of the attached input lines  that has data  to seen. The  multiplexer scans the input lines accept portions of data until a frame is felled and then sends the frame across the link. If  there are not enough data to  fill all the  slot s in a frame the frame a transmitted only partially filled thus full link capacity  may not be used 100 percent   of the time. But  the ability to allocate time slots  dynamically coupled with  the lower  ration of the slots  to input  greatly reduces the likelihood and degree  of waste.



Posted Date: 3/2/2013 6:12:48 AM | Location : United States

Related Discussions:- Asynchronous or statistical time division multiplexing, Assignment Help, Ask Question on Asynchronous or statistical time division multiplexing, Get Answer, Expert's Help, Asynchronous or statistical time division multiplexing Discussions

Write discussion on Asynchronous or statistical time division multiplexing
Your posts are moderated
Related Questions
Question: (a) In relation with a cellular network architecture, describe the following terms: (i) Clusters (ii) Pico cells (iii) Nano cells (iii) Cell breathing (b)

Q. Show the Congestion control in TCP? Congestion control in TCP TCP assumes that the cause of lost segment is due to congestion in the network Retransmission of

Describe any good security technology A good security technology should be powerful enough to support the features that the administrators need, including rules validation to i

Explain how the lan model be developed The LAN model can be developed incrementally. If LAN is just a long cable. it cannot be brought down by single failure (if servers are re

Question 1 Explain the process of Components Identification and call establishment Question 2 Discuss on Basic services in GSM Question 3 Explain the Protocols Use

What is a difference between a domain and workgroup?

Q. Error Correction in Burst Error Correction? Error Correction-Burst Error Correction In its place of sending all the bits in a data unit together we can organize "N

Question 1 A) Explain briefly the advantages wireless communication systems                   B) What is a cellular network? Question 2 Explain fundamental architecture of

Reverse Address Resolution Protocol is used to get a layer 3 address if the MAC address is called which then facilitates the loading of the O/S.