Dual Transfer Mode Concepts

Dual Transfer Mode Concepts

Last updated: December 2, 2008

Dual Transfer Mode (DTM) is the simultaneous existence of both a Circuit Switched (CS) connection and a Packet Switched (PS) session. The simultaneous CS and PS connections can be activated on the same ARFCN and frame. The test set offers two test mode operating modes for receiver testing of adjacent timeslots which can use different channel coding and modulation formats -GMSK or 8PSK, in addition to the Active Cell operating modes.

"For DTM, a multislot configuration consists of a single traffic channel and one or more full rate packet data traffic channels together with associated control channels allocated to the same mobile station. This multislot configuration may occupy up to 3 basic physical channels." (3GPP TS 05.02 version 8.10.0 Release 1999)

The PS data can be sent both on the timeslot used by the CS connection and the timeslot(s) not used by the CS connection. The timeslot configurations are restricted so that the timeslots allocated in each direction are contiguous and there is only one timeslot allocated to the CS connection.

The following figure shows an example of a 2x3 (2 uplinks, 3 downlinks) multislot configuration for a class A mobile in DTM.

There are three Layer 3 RR management messages that facilitate DTM operation.

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