User's Manual

40mW ACS User Guide Technical Introduction iii
PAS System
3.2 Traffic Management
3.2.1 Stand-alone ACS
In the case of an isolated ACS there are 4 time slots installed for radio links. One
slot is a control channel for signaling and the other three are traffic channels. The
number of accommodated subscribers in that ACS covering the zone calculated
according to the Erlang-B model is as follows:
Erlang per zone: (3 T-chs, GOS=5%) = 0.899 Er
Subscribers (FSU or PSs): (0.899 ÷ 0.05) = 18 Subscribers
3.2.2 Group controlled ACSs
Using a group configuration, up to eight ACSs in the same group share one
Control Channel, which is useful for high traffic areas. One master ACS can
control a maximum of seven slave ACSs in the same area. The master ACS has
one control channel while the left 31 channels of these 8 ACSs are for traffic
channels.
RPC
Cchx 1
Zone
8 ACSs
Group Control Operation
Slave
Tchx 3
Tchx 4
Master
Slave
Tchx 4
Slave
Tchx 4
Slave
Tchx 4
Slave
Tchx 4
Slave
Tchx 4
Slave
Tchx 4
Figure3-3 Group Control ACSs
In an eight ACSs group control mode, the number of accommodated subscribers
in the group control coverage zone is calculated in accordance with the Erlang-B
model as follows:
z Erlang per zone : (31 T-chs, GOS=5%) = 25.773 Er
z Subscribers (FSU or PSs): (25.773 ÷ 0.05 ) = 515 Subscribers
The comparison for the number of accommodated subscribers between the group
controlled ACSs and non-group ACSs is shown in Figure3-4.