A timespacetime (TST) switch. TSI
= time-slot interchanger.
l is the number of space-stage time slots and c is the number of external TDM
time slots (Ref. 3).
Space Time Space Switch
. A spacetimespace switch reverses the
order architecture of a TST switch. The STS switch consists of a space crosspoint
matrix at the input followed by an array of time-slot interchangers whose ports feed
another cross-point matrix at the output. Such a switch is shown in Figure 6.21. Consider
this operational example with an STS. Suppose that an incoming time slot 5 on port No. 1
must be connected to an output slot 12 at outgoing port 4. This can be accomplished by
time-slot interchanger No. 1, which would switch it to time slot 12; then the outgoing
space stage would place that on outgoing trunk No. 4. Alternatively, time slot 5 could
be placed at the input of TSI No. 4 by the incoming space switch, where it would be
switched to time slot 12, and then out port No. 4.
A spacetimespace switch.
Space switch array ( m × n) TSI Space stage Time stage Space stage Space switch array ( n × p) TSI TSI TSI Figure 6.21 A spacetimespace switch.