The Closed Loop Power Control measurement can not be concurrent with other measurements. Hence starting the CLPC measurement will turn off any other measurement that is active, and vice versa.
Last updated: 2014-11-28
Closed Loop Power Control (CLPC) Measurement Description
Closed Loop Power Control (CLPC) Measurement Parameters
Closed Loop Power Control (CLPC) Measurement Results
Taking Advantage of CLPC for Dynamic Power Measurements
Closed Loop Power Control (CLPC) measurement, as defined in TS 34.122 Section 5.4.1.4, is used to test the ability of the UE transmitter to adjust its output power in accordance with one or more TPC commands received in the downlink. The power control step is the change in the UE transmitter output power in response to a single TPC command (TPC_cmd) arrived at the UE.
The closed loop power is defined as the relative power differences between RRC filtered mean power of original (reference) timeslot and RRC filtered mean power of the target timeslot without transient duration. In accordance with the minimum requirements of the standard (see Minimum Requirements for the CLPC Measurement), two kinds of relative power are measured:
REL1POW: If the target timeslot is in subframe f, the reference timeslot is in subframe f-1.
REL10POW: If the target timeslot is in subframe f, the reference timeslot is in subframe f-10.
When the CLPC measurement is initiated, the UL CL Power Ctrl Mode is no longer used to control the TPC pattern. Rather, you must specify the number of Down TPC and UP TPC commands that will be sent to the UE, see Closed Loop Power Control (CLPC) Measurement Parameters. The sequence of DOWN TPC commands followed by the sequence of Up TPC commands are sent on the downlink traffic slots, one TPC command per one subframe. When the measurement is finished, the result about whether the UE passes the measurement (whether the UE has ever exceeded the limit) is displayed, see Closed Loop Power Control (CLPC) Measurement Results.
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The Closed Loop Power Control measurement can not be concurrent with other measurements. Hence starting the CLPC measurement will turn off any other measurement that is active, and vice versa. |
This measurement requires the calibration data of the measurement receiver path gain, which are part of the results of the measurement calibration, see Calibrate Measurements.
During the CLPC measurement,
Measured Steps: If the TPC command sequence for this measurement are from subframe f_sta to subframe f_end,
for absolute power, TS1 in subframe of (f_sta) to (f_end+1) will be measured. The total number of measured steps is number of DOWN TPCs + number of UP TPCs + 1.
for REL1POW, TS1 power in subframe of (f_sta+1) to (f_end+1) will be measured. The total number of valid steps is number of DOWN TPCs + number of UP TPCs.
for REL10POW, TS1 power in subframe of (f_sta+10) to (f_end+1) will be measured. The total number of valid steps is number of DOWN TPCs + number of UP TPCs – 9.
Checked Steps: For the relative power step results (either REL1POW or REL10POW), checked steps refers to the steps that will be compared (checked) with its limit.
During the steps in response to the DOWN TPC commands:
for REL1POW, the checked steps will be from the first step whose power is NOT higher than (Maximum Power – Check Offset to Maximum Power) to the step after which the power is lower than (Minimum Power + Check Offset to Minimum Power).
for REL10POW, the checked steps will be from the 10th step to the step after which the power is lower than (Minimum Power + Check Offset to Minimum Power).
During the steps in response to the UP TPC commands:
for REL1POW, the checked steps will be from the first step whose power is NOT lower than (Minimum Power + Check Offset to Minimum Power) to the step after which the power is higher than (Maximum Power – Check Offset to Maximum Power).
for REL10POW, The steps from the 10th step to the step after which the power is higher than (Maximum Power – Check Offset to Maximum Power).
The following figure shows the typical relation between the measured steps, the checked steps, maximum/minimum power and the maximum/minimum power offset.
_measurement_1.GIF)
The CLPC measurement can only be initiated in TD-SCDMA Test or Active Cell operating mode.
When performing CLPC measurements in TD-SCDMA Test operating mode, as there are no call connection between the test set and the UE, you must set the check limits for REL1POW and REL10POW correctly based on the step size specified on the UE side.
When in Active Cell operating mode, the CLPC measurement can only be initiated successfully when a call connection is established. The check limits for REL1POW and REL10POW should be set based on UL Close Loop Power Ctrl Step Size.
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In Active Cell operating mode, the following settings can not be changed during the CLPC measurement:
Besides, during a call connection, the step size can not be changed by UL Close Loop Power Ctrl Step Size whereas it can be updated by Physical Channel Reconfiguration (see PCR UL CL Power Ctrl Step Size). This may help you to perform the CLPC measurement with different step sizes without having to re-connect. |
Minimum Requirements for the CLPC Measurement
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TPC Cmd |
Transmitter Power Control Range |
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1dB Step Size |
2dB Step Size |
3dB Step Size |
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Lower |
Upper |
Lower |
Upper |
Lower |
Upper |
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Up |
+0.5 dB |
+1.5 dB |
+1.0 dB |
+3.0 dB |
+1.5 dB |
+4.5 dB |
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Down |
-0.5 dB |
-1.5 dB |
-1.0 dB |
-3.0 dB |
-1.5 dB |
-4.5 dB |
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TPC Cmd |
Transmitter Power Control Range after 10 equal TPC_cmd groups |
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1dB Step Size |
2dB Step Size |
3dB Step Size |
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Lower |
Upper |
Lower |
Upper |
Lower |
Upper |
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Up |
+8.0 dB |
+12.0 dB |
+16.0 dB |
+24.0 dB |
+24.0 dB |
+36.0 dB |
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Down |
-8.0 dB |
-12.0 dB |
-16.0 dB |
-24.0 dB |
-24.0 dB |
-36.0 dB |
Number of Down/Up Steps: specifies the number of DOWN or UP TPC commands that are sent to the UE.
Maximum/Minimum Power Offset: specifies the offset to the maximum or minimum power of the measurement, where the maximum/minimum power is the maximum/minimum power in all measured steps. See REL1POW measurement example.
One Step Upper/Lower Limit: REL1POW should follow: Lower Limit ≤ |REL1POW| ≤ Upper Limit. If the operating mode is Active Cell, you should set the REL1POW limits according to UL CL Power Ctrl Step Size.
Ten Steps Upper/Lower Limit: REL10POW should follow: Lower Limit ≤ |REL10POW| ≤ Upper Limit. If the operating mode is Active Cell, you should set the REL10POW limits according to UL CL Power Ctrl Step Size.
Maximum Power Upper/Lower Limit: the maximum absolute power should neither be lower than its lower limit nor be larger than its upper limit.
Minimum Power Upper Limit: only upper limit is provided for the minimum absolute power, which should not be larger than its upper limit.
Trigger Source: see Trigger Source. It is recommended that you use protocol as the trigger source for the CLPC measurement.
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There should be no RF signal input to the receiver of the test set if RF RISE is selected as the trigger source. |
Trigger Delay: see Trigger Delay.
Measurement Timeout: see Measurement Timeout
Integrity Indicator: see Integrity Indicator.
Overall Pass/Fail: See FETCh:TCLPower:TRACe:FAIL?
Results associated with each step, including:
Absolute mean power of the step
REL1POW
REL10POW
Pass/Fail
For GPIB commands, see FETCh:TCLPower:STEP?<sp><step index>
Note that the Pass/Fail indicator is only available for the measured steps that are "checked" with the upper or lower limits. If the reference step is not available, this step is not checked. For example, the step 0 for REL1POW and step 0 to 9 for REL10POW will not be checked during the measurement.
Maximum/Minimum Power: the maximum/minimum mean power among all measured steps.
Step Index: the index for the maximum/minimum power step.
Pass/Fail: the maximum absolute power should neither be lower than its lower limit nor be larger than its upper limit. The minimum absolute power among all steps should not be larger than its upper limit.
For GPIB commands, see FETCh:TCLPower:MAXimum:POWer? and FETCh:TCLPower:MINimum:POWer?
Results associated with the worst step: The worst step is for the step whose relative power (REL1POW or REL10POW) is closest to its upper or lower limit among all checked steps.
Step Index: the index of the worst step.
Absolute Power: the absolute power of the worst step.
Worst REL1POW/REL10POW: the REL1POW/REL10POW of the worst step.
The graphical trace presents up to 300 steps of closed loop power statistics. A typical measurement result is shown as below:
_measurement_3.GIF)
You can also query the trace results by GPIB commands of FETCh:TCLPower:TRACe[:ABSolute]?, FETCh:TCLPower:TRACe:RELative?, FETCh:TCLPower:TRACe:RELative10? and FETCh:TCLPower:TRACe:FAIL?.
The first step power is expected to be within ±6 dB of the expected power and the relative power difference between the adjacent step is expected to be within ±6 dB.
Input signal level into the test set's RF IN/OUT connector is between -55 dBm and +28 dBm, in a 1.28 MHz bandwidth
For Non-HSDPA channel type, the frequency of the measured signal should be within 20KHz from the expected receiver frequency; For HSDPA channel type, the frequency of the measured signal should be within 2KHz from the expected receiver frequency.
The CLPC measurement can also be used to measure dynamic power, which also performs a series of consecutive power measurements on the UE. The following considerations should be taken if you want to perform dynamic power measurements with CLPC:
Requirements for the input signals:
The input signal should be normal TD-SCDMA bursts in accordance with the technical standards.
The input signal should be consecutive in time and should be in the same channel/frequency.
There should be only one uplink timeslot in each subframe, and the uplink timeslot should be at the same position within each subframe (e.g. all subframes with the uplink TS2 is acceptable).
The maximum supported step length of the signal is 300, which is also the sum of the maximum supported UP and DOWN step numbers in CLPC measurement.
The first step power is expected to be within ±6 dB of the expected power, and the relative power difference between the adjacent step is expected to be within ±6 dB.
If RF Rise is selected as the trigger source, there should be no RF signals before the first step.
Requirements for setting up the measurement parameters:
Trigger Source: It is recommended to use the RF Rise as the trigger source for dynamic power measurement. When external trigger is selected, you should supply an external trigger signal via the rear panel TRIG IN connector in order to trigger data capture.
The number of UP and DOWN steps: The dynamic power measurement does not require the UE to react to the UP/DOWN TPC commands, so the two numbers no longer indicate the number of UP or DOWN TPC commands the test set will send to the UE (as they do in the CLPC measurement). As the test set supports at most 150 UP TPC commands and 150 DOWN TPC commands for each measurement, you should only ensure the sum of the two numbers does not exceed 300.
Dynamic Power measurement results :
The power for all the measured steps can be queried by FETCh:TCLPower:TRACe:ABSolute?
GPIB Commands: SETup:TCLPower, FETCh:TCLPower