Handover Control

Network Assisted Cell Change (NACC) Handover Procedure

The NACC Handover procedure provides enhancements to the standard handover mechanism, whereby the DUT (supporting the NACC Handover procedures) may perform the exchange of the destination cell's SI messages on the source cell prior to performing the actual handover to the destination cell. This allows the required destination cell's SI content to be available to the DUT much sooner than the case whereby it must acquire from the BCH of the destination cell.

You can enable the NACC Handover procedure by setting NACC Completion message, Cell Change Notification GSM State and Cell Change Notification 3G state parameters. the Packet Neighbor Cell Data and PMO Forces NC2 State parameters also affect the NACC Handover procedure. See Handover Control Parameters for more information.

The NACC Handover procedure is only applicable in the Active Cell operating modes. The NACC Handover procedure is supported in all the connection types except SRB loopback.

PS Handover Procedure

The PS Handover adds the capability for a handover of a DUT in the Packet Transfer state to essentially maintain packet resources as part of the handover procedure. Therefore the PS Handover procedure obviates the need to perform resource re-establishment on the BCH of the destination cell before packet transfer can continue following the handover.

You can enable the PS Handover procedure by setting the PS Handover State. The Packet Neighbor Cell Data and PMO Forces NC2 State parameters also affect the PS Handover procedure. See Handover Control Parameters for more information.

In general, a network which supports PS Handover functionality shall also support Packet Flow Context (PFC) procedures. Therefore, if PFC procedures are disabled, the configuration of the PS Handover functionality is also disabled. See Cell Operation for more information.

PS Handover functionality is only applicable when there is an external device connection present between the source and destination cells associated with the procedure.

Access to the PS Handover State parameter can be obtained by selecting Handover Parameters ( F10 ), Ext Handover Setup ( F10 ). Note that the external handover menu is only available if the test set currently have an External Device Connection .

The PS Handover procedure in only applicable in the Active Cell operating modes and in the Auto connection type.

Frame Synchronization

To perform anything other than a non-synchronized handover the frame structures in the two-cell test system have to be synchronized. The Frame Synchronization allows the slave test set to synchronize to the BCH of the master in the two cell test system with a given offset of bit positions (Bit Offset) and frame number (Frame Number Offset). You can also set the Power Correction Gain by which the power level that the master is instructed to output is decreased to compensate for gains in the RF path between the master and slave.

The terminology "slave" and "master" are used to refer to the test sets involved in synchronization. The test set at which the synchronization process is initiated is the slave and it adjusts its frame structure to align with the other unit which is the master. Only the slave is aware that the two frame structures are aligned.

The frame synchronization feature requires the following connections to be present between the slave and master units:

• Both units must use a common 10 MHz reference clock to ensure that the frame structures remain synchronized after the synchronization process has completed. Either the 10 MHz clock output from one unit must be connected to the 10 MHz clock input of the other, or both units must use a common 10 MHz clock from a source external to both of them.
• Both units must be connected to a common LAN and have established connection using the External Device Connection control on the System Config screen (2 of 2) .
• There must be an RF connection between the two units capable of delivering -30 dBm to the slave unit from the master since the synchronization is done by the slave instrument demodulating the BCH of the master to align its frame structure using the SCH.

Of the above connections only the 10 MHz clock one must be maintained continuously after the synchronization process has completed.

To start Frame Synchronization, you should first send the Frame Synchronization event. The Frame Synchronization event causes the slave to align its BCH frame structure with the master's. The procedure has two phases, in the first phase the frame of the slave unit is shortened by 2 bit periods until the starting points of the frames are aligned, in the second phase a single extended frame is created to accommodate the Frame Synchronization Offset. Positive values of Frame Synch Offset cause the frame structure of the slave unit to lead the frame structure of the master by that number of bit periods. Positive values of Frame Number Offset cause the frame number of the slave unit's aligned frame to be greater than that of the master unit (modulo 2715648).

See Frame Synchronization Setup for more information about how to set the Frame Synchronization parameters.

Synchronized Handovers

The handover type that can be implemented using the two-cell architecture include:

• Non-synchronized handover
• Synchronized handover
• Pre-synchronized handover
• Pseudo-synchronized handover

These handovers all make use of the HANDOVER_COMMAND but they provide different Information Elements within it. The Synchronization Indication may be omitted or included to inform the mobile of the type of handover. If the type of handover is pre-synchronized a Timing Advance IE is included. If the handover type is pseudo-synchronized the Time Difference (Report Observed Time Difference) IE is included.

The Synchronized Handover feature requires the following connections to be present between the slave and the master units:

• The common 10 MHz clock connection required to maintain frame synchronization (see 3.4.1).
• The common LAN connection (see 3.4.1).

See External Handover Setup for more information about how to set the Synchronized Handover parameters.

Handover Control Parameters

Parameter	GPIB Command
Packet Timeslot Reconfigure	CALL:(PDTCH|PDTChannel):PMESsage:PTReconfig
Packet Power Timing Advance	CALL:(PDTCH|PDTChannel):PMESsage:PPTadvance
Packet Neighbor Cell Data	CALL:(PDTCH|PDTChannel):PMESsage:PNCData[:STATe]
PMO Forces NC2 State	CALL:(PDTCH|PDTChannel):PMESsage:(PMORder|PMO):NC2[:STATe]
NACC Completion Message	CALL:(PDTCH|PDTChannel):PMESsage:NACChange:COMPletion

The following procedure details how to set the Handover Control parameter.

1. Press the CALL SETUP screen key.
2. Press the left More key until screen 2 of 3 is displayed.
3. Press Protocol Control ( F4 )
4. Press RLC/MAC ( F2 )
5. Press Handover Control ( F3 ) and the Handover Control menu appears in the center of the screen.
6. Use the knob to highlight and set the Handover Control Parameters.

Note the PS Handover State parameter is not located in the Handover Control menu. See PS Handover Procedure for details on how to set the PS Handover State.