Channel Distribution Function
•
Configuration includes setup of new connections and release of
connections no longer required. Connections which are the same
in the old and the new configuration are left undisturbed.
•
Idle pattern is transmitted on unoccupied timeslots in the transport
network interface. An unoccupied timeslot is a timeslot which has
no channel assigned to it. The idle pattern is 01010100 for a 2
Mbit/s system and 01111111 for a 1.5 Mbit/s system.
•
If the timeslot is partly used, an idle pattern will be used for all
unoccupied 16 kbit/s sub-timeslots within that timeslot. The
subslot idle pattern is 01 for 2 Mbit/s systems and 11 for 1.5
Mbit/s systems.
•
If the timeslot is partly used, an idle pattern will be used for all
unoccupied 16 kbit/s sub-timeslots within that timeslot. The
subslot idle pattern is 01 for 2 Mbit/s systems and 11 for 1.5
Mbit/s systems.
•
Maximum capacity (Transport Network Interface) is 31 timeslots
between the BSC and BTS for a 2 Mbit/s system and 24 timeslots
for a 1.5 Mbit/s system. This corresponds to one PCM line
towards the BSC.
•
One signalling channel can be switched to each TRX, the capacity
of this channel is 16, 32 or 64 kbit/s.
•
Eight 16 kbit/s traffic channels can be switched to each TRX, that
is, one for each available ATSR.
•
24 signalling channels can be switched to the concentrator, the
capacity of each channel is 64 kbit/s.
•
The physical mapping, which is needed to configure the switch, is
based on ICPs. Each ICP represent a 16 kbit/s subrate connection
point.
•
The ICPs in the range 4 – 255 defines the incoming PCM
timeslots according to Table 25 on page 219. The ICPs for
timeslots 25 – 31 are only valid for 2 Mbit/s systems.
The range 256 – 351 defines the concentrator.
The ranges 512 – 575 and 640 – 711 define the TRXs, see Table
26 on page 220.
Table 25
ICPs range 4 – 255
ICP
Usage
4-7
PCM-A
TS1
8-11
PCM-A
TS2
...
...
....
122-127
PCM-A
TS 31
132-135
PCM-B
TS 1
136-139
PCM-B
TS 2
...
...
...
250-255
PCM-B
TS 31
EN/LZT 123 2697
R5A
1998-08-13
219 (306)
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