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Troubleshooting Compressed Mode Operation
Last updated: March 3, 2009
This section is only applicable to the lab application
.
Possible Setup Issues
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The test set supports compressed mode on the following connection types and channel configurations: RB Test Mode, HSDPA RB Test Mode, AMR voice, CS Data/Video Call, PS Data, and HSDPA PS Data. The 384k RMC is not supported as it is not compressible by spread factor reduction because the uplink 384k DPCH already uses the minimum DPCH spreading factor of 4. At this time, due to processor limitations, compressed mode is not supported on any 384k downlink channels.
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The test set does not support compressed mode for the HSUPA RB Test Mode and HSUPA PS Data channel configurations.
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The downlink DPCH channelization codes available during compressed mode are limited to those that would not cause collisions with other downlink channels during compressed frames. See
Channel Types Supported in Compressed Mode and Valid Channelization Codes
.
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When you enable compressed mode with UE measurements, the test set sends a Measurement Control message to the UE which includes a list of cells to measure (the SIB11 cell info list for inter-frequency cells or for GSM cells, depending upon the
Measurement Configuration
setting). Thus, before enabling compressed mode with UE measurements, ensure that the cells in the SIB11 cell info lists are in a frequency band that is supported by your UE (some UEs will drop the connection if ordered to measure a cell in a frequency band they don't support).
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3GPP TS 25.331 v5.17.0 s8.6.6.28 states that the UE's behavior is undefined if the network sets the Timing Indication IE to Initialise on a non-hard handover (i.e. where the UARFCNs and one or more Primary Scrambling Codes remain unchanged as part of the reconfiguration). Thus, if you perform a Physical Channel Reconfiguration to enable/disable comprised mode with
CM PCR Timing Indication (CFN Handling)
set to
Initialise
, the UE may drop the call, ignore or reject the reconfiguration request, or report a reconfiguration failure. See
Timing Indication (CFN Handling)
for additional details.
Configuring the TGPSs (Transmission Gap Pattern Sequences)
Retrieving UE Reported Measurement Results
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To receive UE reported measurement results when compressed mode is enabled, ensure that
UE Measurements in Compressed Mode
is set to
On
, and that the
Measurement Configuration
setting matches the
TG Measurement Purpose
for at least one active TGPS.
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The Measurement Control message sent to activate compressed mode can only contain one value for the MeasurementType information element, either interRATMeasurement (GSM cells) or interFrequencyMeasurement (W-CDMA cells). Thus, for a given compressed mode activation, the test set can only order the UE to measure either W-CDMA or GSM cells. For a given compressed mode activation you can include multiple TGPSs with FDD (W-CDMA) and GSM measurement purposes, but to change which type of cells are being measured by the UE you must disable compressed mode, change
Measurement Configuration
, then enable compressed mode.
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Per 3GPP TS 25.331 s8.6.7.5, if
GSM Meas BSIC Verification
is set to
verifiedBSIC
, the UE will only report measurement results for cells for which it was able to decode the BSIC and match it to the NCC and BCC specified in the SIB11 GSM cell info list. If your UE does not support BSIC verification and you set
GSM Meas BSIC Verification
to
verifiedBSIC
, your UE will likely return empty Measurement Reports. If your UE supports BSIC verification you may still receive empty Measurement Reports when
GSM BSIC Verification
is set to
verifiedBSIC
if you do not include an active TGPS with a
TG Measurement Purpose
of
GSM Initial BSIC ID
or
GSM BSIC Reconfirmation
(see 3GPP TS 25.331 s8.6.7.6).
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Depending upon your UE's compressed mode implementation, you may need to set
GSM Meas BSIC Verification
to
verifiedBSIC
before your UE will perform the Initial BSIC Identification or BSIC Reconfirmation procedures.
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The
GSM RSSI Measurement Reporting Quantity
and
Interfreq Measurement Reporting Quantity
parameters determine how many Measurement Reports the UE returns. After the UE has returned the number of reports specified by these parameters, it stops reporting measurement results.
Operating Considerations
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See
Additional Considerations While in Compressed Mode Operation
.
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The test set supports compressed mode by spreading factor reduction in both the downlink and uplink. Note, however, that the test set does not transmit downlink compressed frames at an increased power level; compressed frames are transmitted at the same power level as non-compressed frames - the power level determined by the
Cell Power
setting.
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Changing the
Downlink Frame Structure Type
setting does not change the structure of the downlink signal from the test set. Regardless of the
Downlink Frame Structure Type
setting, during compressed mode frames the test set sends the TPC field and pilot field in every slot (even the slots that occur during the transmission gap). Changing the
Downlink Frame Structure Type
setting only changes the frame structure signaled to the UE (which changes what the UE looks for during the downlink transmission gaps).
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If TGPRC is non-zero, when the specified number of transmission gap pattern repetitions have occurred, the state of that TGPS changes from
On
to
Off
.
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See
Compressed Mode Operation While in FDD Test Operating Mode
.
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