Nortel Networks DCT1900 manual System Architecture, Synchronization Topology

Technical Product Manual - DCT1900

System Description, System Overview

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:

zSeveral 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.

zA 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.

Slave

Slave

Master Slave Slave

Slave	Level 1	Slave
		Level 2

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

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