Nortel Networks DCT1900 - Manual (Page 28)

Technical Product Manual - DCT1900
System Description, System Overview
2-6 System-DCT1900/R8/mw
© 2000-2005
System Architecture
The DCT1900 system provides a wireless infrastructure between the user and the MS/PBX. The
system can serve multiple users at the same time.
The system can be split up in a fixed part (made up of one RE and multiple Base Stations) and
many Portable Telephones. The basic configuration of a DCT1900 system allows:
z Several systems to provide the same service as one large system. A user with one Portable
Telephone is able to walk around in different areas covered by different systems without
interrupting an ongoing call. This feature is known as inter-system handover.
z A user can use the same Portable Telephone in another area or remote site, keeping the same
number. This feature is known as inter-site roaming.
Different aspects of the DCT1900 system are discussed below.
Radio Exchange Synchronization (DCT1900 Mobility Configuration only)
In order to support the inter-system handover capability, REs have to be synchronized. REs are
synchronized using a master/slave concept, where one master RE supplies a synchronization
signal to a number of slave REs. A slave RE can act as a master for three further slave REs, thus
creating a multi level star network with a maximum of two levels, see Figure 2-3.
Figure 2-3 Synchronization Topology
In the master RE, it is possible to select the synchronization source between an internal clock and
a T1 or E1 interface to the Mobility Server.
In case the synchronization is lost (e.g. due to cable failure) on a slave RE, the slave will generate
an alarm on the Mobility interface to notify the MS. However, the slave will continue to operate and
Master Slave
Slave
Slave
Slave
Slave
Level 1
Level 2
Slave