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Technical Product Manual - DCT1900
System Description, Radio Exchange Boards
System-DCT1900/R8/mw 4-5
© 2000-2005
4.6 Digital Trunk Unit - DTU-E1
4.6.1 CCS - REX-BRD0003 or 2/ROFNB 157 13/6
The DTU provides the digital interface between the MS and the RE. The physical connection with
the MS is established via twisted pair cables.
Every DTU board contains 2 DTCs (see Figure 4-4), each equipped with identical firmware. Both
DTCs support the Common Channel Signalling (CCS) interface.
Each CCS interface provides 30 (total 60 per board), communication channels to which Portable
Telephones are assigned dynamically. These channels are shared by the Portable Telephones
which means that although the RE can handle more Portable Telephones, only 30 calls per CCS
interface can take place at the same time. The maximum number of Portable Telephones a RE can
handle depends on the GOS (grade of service) and the traffic capacity of the RE configuration.
However, there is a maximum of 60 concurrent off hooks and a maximum of 1 DTU-E1 card per
mobility RE.
Fig. 4-4 DTU-E1 CCS
L2
DTC2
L1
DTC1
BC
L2 L1BC
Channels
31 - 60
Channels
1 - 30
2 Mbit/s
Trunk
2 Mbit/s
Trunk