Technical Product Manual - DCT1900System Description, Radio Exchange BoardsSystem-DCT1900/R8/mw 4-5© 2000-20054.6 Digital Trunk Unit - DTU-E14.6.1 CCS - REX-BRD0003 or 2/ROFNB 157 13/6The DTU provides the digital interface between the MS and the RE. The physical connection withthe MS is established via twisted pair cables.Every DTU board contains 2 DTCs (see Figure 4-4), each equipped with identical firmware. BothDTCs support the Common Channel Signalling (CCS) interface.Each CCS interface provides 30 (total 60 per board), communication channels to which PortableTelephones are assigned dynamically. These channels are shared by the Portable Telephoneswhich means that although the RE can handle more Portable Telephones, only 30 calls per CCSinterface can take place at the same time. The maximum number of Portable Telephones a RE canhandle 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 permobility RE.Fig. 4-4 DTU-E1 CCSL2DTC2L1DTC1BCL2 L1BCChannels31 - 60Channels1 - 302 Mbit/sTrunk2 Mbit/sTrunk
