MUS/TSI/DEMUX: Time-Switch Handling Methods
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Questions and Answers

The memory has as many ______ as there are time slots.

cells

The time switch works well for a single ______–outlet switch.

inlet

The data store is ______ with capacity to store one full frame of data.

RAM

The speech data store is ______ bytes long for DS1 (1.544 Mbps) with 24 channels of 8 bits.

<p>24</p> Signup and view all the answers

Control is associated with ______ lines and specify which inputs are to be connected to the associated outputs.

<p>output</p> Signup and view all the answers

T = 1/(2*______ Rate)

<p>Slot</p> Signup and view all the answers

A time slot represents one ______ channel.

<p>voice</p> Signup and view all the answers

The time-slot counter or processor is a functional block of the ______.

<p>Time-Switch</p> Signup and view all the answers

The time duration of an 8-bit time slot in the DS1 case is ______ µsec.

<p>5.2083</p> Signup and view all the answers

The writing of incoming time slots into the speech memory can be controlled by a ______ counter.

<p>time-slot</p> Signup and view all the answers

The MUS/TSI/DEMUX has two basic memory blocks: 1) Memory for ______, and 2) Memory for control.

<p>speech</p> Signup and view all the answers

If the memory cycle time is 125 nano seconds, then maximum number of slots will be ______, which can accommodate 250 connections.

<p>500</p> Signup and view all the answers

The implementation complexity for an STS switch with 2048 channels organized in ______ TDM lines, with 8 bits/channel, 128 channels/frame is given by.

<p>16</p> Signup and view all the answers

The probability of having a link busy is ______ and the maximum blocking probability for the STS switch is 0.002.

<p>0.1</p> Signup and view all the answers

The maximum blocking probability for the STS switch is ______.

<p>0.002</p> Signup and view all the answers

The number of channels per frame is ______.

<p>128</p> Signup and view all the answers

The total number of channels is ______.

<p>2048</p> Signup and view all the answers

The number of bits per channel is ______.

<p>8</p> Signup and view all the answers

The probability that the same time slot on a different ______ is chosen by the other subscribers on the same inlet.

<p>outlet</p> Signup and view all the answers

The Implementation Complexity IC is equal to Nx + ______100.

<p>NB</p> Signup and view all the answers

The number of crosspoints will be significantly decreased, whilst the number of ______ will be increased.

<p>bits</p> Signup and view all the answers

The TS structure is of ______ nature.

<p>blocking</p> Signup and view all the answers

A and B can be moved to the same time slot but during that time slot, the ______ line can be connected to C's line or D's line but not both.

<p>inlet</p> Signup and view all the answers

The Highest contribution of S-stage could be reduced by ______ the TDM lines.

<p>multiplexing</p> Signup and view all the answers

STS is more efficient when ______ is greater than 0.2

<p>p</p> Signup and view all the answers

The number of crosspoints for S stage is given by ______ squared

<p>N</p> Signup and view all the answers

The total number of memory bits for S and T stages is given by ______ log2 N plus ______ bits

<p>Nl 16</p> Signup and view all the answers

The number of channels in each link is ______ for the given 131,072-channel TSSST switch

<p>128</p> Signup and view all the answers

The maximum blocking probability of the TSSST switch is ______

<p>0.002</p> Signup and view all the answers

The number of TDM input links is ______ for the given 131,072-channel TSSST switch

<p>1024</p> Signup and view all the answers

Study Notes

Time-Slot Interchange (TSI) and Time Switch (T)

  • A time switch handles 23 stations besides the calling subscriber, with 24 cells.
  • Time-slot interchange: time switch (T) uses sequential write and random read, or random write and sequential read.
  • Data store is RAM with capacity to store one full frame of data; for DS1, it is 24 bytes long.
  • Two ways to handle a time switch:
    • Sequential Write/Random Read: time-slots are written into the speech memory as they appear in the incoming bit stream.
    • Random Write/Sequential Read: incoming time-slots are written into memory in the order of appearance in the outgoing bit stream (desired output order).

Switch Matrix Control (I)

  • Cross-point selection within a matrix can be done in two ways:
    • Output associated control: control is associated with output lines and specify which inputs are to be connected to the associated outputs.
    • Input Associated control: control is associated with input lines and specify to which outputs the respective inputs are to be connected.

Time-Switch or TSI

  • Has three basic functional blocks:
    • Memory for speech
    • Memory for control
    • Time-slot counter or processor
  • Data store memory is accessed twice during each link time slot.
  • The required memory operation speed t is: t = 1/(2*Slot Rate)

Drill Problem

  • If the memory cycle time is 125 nano seconds, then the maximum number of slots will be 500, which can accommodate 250 connections.
  • Implementation complexity for an STS switch with 2048 channels organized in 16 TDM lines, with 8 bits/channel, 128 channels/frame.

Three Stage Switch Combinations

  • The TS structure is of blocking nature.
  • A and B are the subscribers using different time slots on the same line want to connect to two subscribers C and D using the same time slot on different lines.
  • Implementation complexity: p STS is more efficient; p > 0.2: IC for STS > IC for TST => TST is more efficient.
  • Having this result, in practice TST is preferred; eventually, for large switches, TST could be replaced by TSSST.

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Description

Learn about the two approaches to handling time switches in MUS/TSI/DEMUX systems: Sequential Write/Random Read and Random Write/Sequential Read. Understand the difference between these methods and how they affect the output order. Test your knowledge of time-slot handling in speech memory!

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