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8960 W-CDMA/HSPA Online User's Guide
E1963A, E6703E
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Inner Loop Power Measurement Description

Last updated: January 16, 2009

How is an Inner Loop Power Measurement Made?

Inner loop power control in the uplink is the ability of the UE to adjust its output power in accordance with one or more TPC (transmit power control) commands received in the downlink. When the UE is not in soft handover, only one TPC command is received in each timeslot. The UE's output power changes in response to a single TPC command, TPC_cmd, derived at the UE based on the power control algorithm. TPC_cmd, along with the power control step size, determines the UE transmit output power. The power change is applied in the timeslot adjacent to the timeslot in which the TPC command is received. For example, the power change derived from a TPC command in the 10th timeslot is applied to the 11th timeslot.

The inner loop power measurement is made through a root-raised cosine (RRC) filter with a roll off of alpha=0.22 and a bandwidth equal to the chip rate (3.84 MHz). The test set measures the mean power in each timeslot, excluding the transient duration. The transient duration is from 25 microseconds before the slot boundary to 25 microseconds after the slot boundary. The relative power difference is calculated for adjacent TPC_cmds and also for 10 TPC_cmd groups (10 timeslots if using algorithm 1 and 50 slots if using algorithm 2).

You can run the inner loop power measurement in Auto Mode or Manual Mode .

The inner loop power test process specified in 3GPP TS 34.121 5.4.2 consists of a series of test segments (referred to as Test Steps in the standard, see Inner Loop Power Control Test Steps ). The test set allows you to run one Test Segment at a time.

Inner Loop Power Control Test Steps

Auto Mode

Auto mode is used to run a single test segment as specified by 3GPP TS 34.121 5.4.2. This is achieved by selecting any one of the test segments (referred to as Test Steps in the standard) from the Test Segment menu and then initiating the measurement. You can perform the entire "Inner Loop Power Control in the Uplink" test by piecing the test segments together.

The test set behavior for each Test Segment is described in the table below. When you initiate the measurement with one of these test segments selected, the test set drives the UE to the proper start power for the test segment (if it is not already at the proper power) and performs a Physical Channel Reconfiguration to the proper power control algorithm and step size values for the test segment (if needed) before beginning the test.

Note that if the test segment requires a Physical Channel Reconfiguration to change to the required power control algorithm and/or step size, when the test segment completes the test set performs another Physical Channel Reconfiguration to return the connection to its pre-measurement configuration. Thus, it will save measurement execution time if you perform a Physical Channel Reconfiguration to the required power control algorithm and/or step size before beginning test of segments E and F or G and H (test segments A, B and C already match the default power control algorithm and step size in the test set).

Test Segment Descriptions
Test Segment Power Control Algorithm Step Size Start Power TPC Command Sequence Sent by Test Set
A Two 1 dB -10 dBm (+/- 1 dB) The TPC commands sent depend upon the Number of Slots setting.
B Two 1 dB -10 dBm (+/- 1 dB) 50 TPC commands with value 1
C Two 1 dB 0 dBm (+/- 1 dB) 50 TPC commands with value 0
Note: Test Segment can not be set to D. Step D in 3GPP TS 34.121 5.4.2 is automatically performed when you initiate Test Segment E. In other words, when Test Segment E is initiated, the test set sets Power Control Algorithm to One , Step Size to 1 dB , and sends TPC commands with a value of 1 until the UE stops increasing its output power. The test set then sends the TPC command sequence for Step E.
E One 1 dB UE's maximum power + Up to 300 TPC commands with value 0 #, *
F One 1 dB UE's minimum power # Up to 300 TPC commands with value 1 +, *
G One 2 dB UE's maximum power + Up to 150 TPC commands with value 0 #, *

H

 One 2 dB UE's minimum power # Up to 150 TPC commands with value 1 +, *
# The test set sends all down bits to the UE until the UE stops decreasing its output power (is stable within +/- 0.5 dB for E, within +/- 1 dB for G).
+ The test set sends all up bits to the UE until the UE stops increasing its output power (is stable within +/- 0.5 dB for F, within +/- 1 dB for H).
* Note: to maintain accuracy, the test set re-ranges its receiver during these sequences. During this re-ranging time, the test set sends a series of alternating power control bits to the UE to hold its output power level.

Manual Mode

Manual mode allows you to build a custom test segment. This is achieved by selecting Manual from the Test Segment menu. In manual mode, the UE is instructed to go to Start Power before starting the test. The test set then measures the UE's response by sending the TPC commands with the Step Size and Power Control Algorithm you've specified until the expected target power is equal to Stop Power . If necessary, the test set performs a Physical Channel Reconfiguration to the proper power control algorithm and step size values before beginning the test.

UE (Mobile Station) Control During FDD Test Operation Mode

When the measurement is made in FDD test mode, the UE should be capable of deriving TPC_cmd commands in test mode. You need to configure the UE to use the proper power control algorithm and the step size before initiating a measurement, as these settings are not signalled to the UE by the test set.

Operating Considerations

No other measurements can be running during the inner loop power measurement. If any measurements are running when an inner loop power measurement is initiated, they are closed and a message is displayed to indicate that they have been closed.

To use this measurement in active cell mode, the UE must be on a call.

The test set does not support testing the UE in compressed mode with this measurement, therefore 3 dB power control step size is not allowed.

The total power of the UE on the uplink consists of the standard W-CDMA channels (UL DPCCH and DPDCH), the HSDPA control channel (HS-DPCCH) and the HSUPA channels (E-DPCCH and E-DPDCH). The target power for active power control sets the DPCCH and DPDCH power levels, so the total UE power when using HSPA is always higher than the target power. The actual offset in power depends on the ?c and ?d values, Delta CQI and Delta Ack/Nack values, and the E-TFCI of the enhanced channel. The mathematical relationship is expressed in the following formula:

For example, if HS-DPCCH is present in addition to DPCCH and 1 DPDCH, the UE Tx RF power will be:

higher than the UE's target power in dB.

Inner Loop Power Measurement Parameters

  • Test Segment

    See Auto Mode .

  • Power Control Algorithm

    This setting is only applicable when Test Segment = Manual (see Manual Mode ). Note, if Start Power is equal to Stop Power , the Power Control Algorithm and Step Size settings can not be changed and are set to Algorithm 2 and 1 dB . The number of slots measured is then determined by the Number of Slots setting.

    For a description of power control algorithms one and two, see UL CL Power Ctrl Algorithm .

  • Step Size

    This setting is only applicable when Test Segment = Manual and Power Control Algorithm = One .

    Step Size is the change in the UE's transmit power in response to a single TPC command.

  • Start Power

    This setting is only applicable when Test Segment = Manual (see Manual Mode ). Note, if Start Power is equal to Stop Power , the Power Control Algorithm and Step Size settings can not be changed and are set to Algorithm 2 and 1 dB . The number of slots measured is then determined by the Number of Slots setting.

  • Stop Power

    This setting is only applicable when Test Segment = Manual (see Manual Mode ). Note, if Start Power is equal to Stop Power , the Power Control Algorithm and Step Size settings can not be changed and are set to Algorithm 2 and 1 dB . The number of slots measured is then determined by the Number of Slots setting.

  • Number of Slots

    This setting is only applicable when Test Segment = Manual and Start Power = Stop Power or when Test Segment = A .

    The following TPC commands are sent, depending upon the Number of Slots setting:

    • 15: 100000101010101
    • 30: 100000101010101111101000001010
    • 45: 100000101010101111101000001010101011111010000
    • 60: 100000101010101111101000001010101011111010000010101010111110

  • Test Thresholds and Tolerances

    For test segments E-H, pass/fail limit checking (as specified by the Transmitter Power Control Pass/Fail Ranges ) and worst case results are determined for the range of measured results bounded by the Minimum Power Threshold for Test (MinPTT) and the Maximum Power Threshold for Test (MaxPTT). You can set MinPTT and MaxPTT manually, or let the test set automatically determine these values.

    To follow the test method specified by 3GPP TS 34.121 5.4.2, set Maximum Power Threshold for Test Control to Auto , set Maximum Output Power Test Tolerance to 0.7 dB , set Minimum Power Threshold for Test Control to Manual , and Minimum Power Threshold for Test Manual to -49 dBm .

    • Maximum Power Threshold for Test Control

      • Manual : MaxPTT is determined by the Maximum Power Threshold for Test Manual setting.
      • Auto : MaxPTT is determined automatically by the test set as follows -
        • Test segments E and G: Prior to starting the test segment, the test set sends all up bits to the UE (to drive the UE to transmit at the highest power possible), then makes a channel power measurement of the UE's output power once it has stabilized. MaxPTT is then set to this measured power level minus the Maximum Output Power Test Tolerance .
        • Test segment F and H: At the end of the test segment (when the UE's output power has stabilized at the highest power it is capable of transmitting), MaxPTT is set to the measured power level minus the Maximum Output Power Test Tolerance .

    • Maximum Power Threshold for Test Manual

      When Maximum Power Threshold for Test Control is set to Manual , this setting specifies the MaxPTT.

    • Maximum Output Power Test Tolerance

      When Maximum Power Threshold for Test Control is set to Auto , this setting allows you to modify the MaxPTT value used by the test set.

    • Minimum Power Threshold for Test Control

      • Manual : MinPTT is determined by the Minimum Power Threshold for Test Manual setting.
      • Auto : MinPTT is determined automatically by the test set as follows -
        • Test segments F and H: Prior to starting the test segment, the test set sends all down bits to the UE (to drive the UE to transmit at the lowest power possible), then makes a channel power measurement of the UE's output power once it has stabilized. MinPTT is then set to this measured power level plus the Minimum Output Power Test Tolerance .
        • Test segment E and G: At the end of the test segment (when the UE's output power has stabilized at the lowest power it is capable of transmitting), MinPTT is set to the measured power level plus the Minimum Output Power Test Tolerance .

    • Minimum Power Threshold for Test Manual

      When Minimum Power Threshold for Test Control is set to Manual , this setting specifies the MinPTT.

    • Minimum Output Power Test Tolerance

      When Minimum Power Threshold for Test Control is set to Auto , this setting allows you to modify the MinPTT value used by the test set.

  • UE Range Time

    Before the test set can measure the UE's response to power control bits, it must drive the UE to the proper starting power as determined by the Test Segment 's start power (see Test Segment Descriptions ) or by the Start Power setting (when Test Segment = Manual ). When the measurement is initiated, the test set sends power control bits to drive the UE to the required start power. The amount of time needed to drive the UE to the proper starting power depends upon the UE's current output power level and the power control algorithm used to drive the UE's output power. The amount of time the test set waits for this initial ranging to complete is determined by the following settings:

    • UE Range Time Control

      When UE Range Time Control is set to Auto , the test set automatically determines a sufficient UE range time and does not begin measuring UE output power until that time has elapsed.

      When UE Range Time Control is set to Manual , when the measurement is initiated, the test set waits a time equal to Manual UE Range Time before beginning measurement of the UE's output power (during this wait time the test set sends power control bits to drive the UE to the required start power). Manual UE range time control is especially useful if you know that the UE's output power is already at the required starting power. In this case, you can set Manual UE Range Time to zero and start the measurement immediately, and thus minimize the measurement execution time.

      GPIB command: SETup:WILPower:MS:RANGe:TIME:CONTrol:AUTO

    • Manual UE Range Time

      This setting determines the UE range time when UE Range Time Control is set to Manual .

      GPIB command: SETup:WILPower:MS:RANGe:TIME:CONTrol:AUTO

  • Transmitter Power Control Pass/Fail Ranges

    You can set the pass/fail ranges applied for each Test Segment (when in Auto Mode ) or in Manual Mode (based on power control algorithm, power step size and direction).

    Auto Mode : The following tables indicate how the pass/fail range settings map to the 3GPP TS 34.121 5.4.2.5 test requirements and the test segments to which they apply:

    3GPP TS 34.121 Table 5.4.2.5.1 Transmitter Power Control Range (with Applicable Test Segments and Pass/Fail Range Settings)
    TPC_cmd Transmitter power control range (all units are in dB)
    1 dB step size 2 dB step size
    Lower Upper Test Segment Lower Upper Test Segment
    +1 +0.4 +1.6 B, F +0.85 +3.15 H
    TX Pwr Ctrl Rng Sngl Step Up 1dB:
    Lwr Lim     and Upr Lim     		TX Pwr Ctrl Rng Sngl Step Up 2dB:
    Lwr Lim     and Upr Lim
    0 -0.6 +0.6 A, B, C -0.6 +0.6 N/A
    TX Pwr Ctrl Rng Sngl Step None:
    Lwr Lim     and Upr Lim     		N/A
    -1 -0.4 -1.6 C, E -0.85 -3.15 G
    TX Pwr Ctrl Rng Sngl Step Dn 1dB:
    Lwr Lim     and Upr Lim     		TX Pwr Ctrl Rng Sngl Step Dn 2dB:
    Lwr Lim     and Upr Lim

       

    3GPP TS 34.121 Table 5.4.2.5.2 Transmitter Aggregate Power Control Tolerance (with Applicable Test Segments and Pass/Fail Range Settings)
    TPC_cmd group Transmitter power control range after 10 equal TPC_cmd group (all units are in dB)
    1 dB step size 2 dB step size
    Lower Upper Test Segment Lower Upper Test Segment
    +1 +7.7 +12.3 F +15.7 +24.3 H
    TX Pwr Ctrl Rng Agg Alg1 Step Up
    1dB: Lwr Lim     and Upr Lim     		TX Pwr Ctrl Rng Agg Alg1 Step Up
    2dB: Lwr Lim     and Upr Lim
    0 -1.1 +1.1 A -1.1 +1.1 N/A
    TX Pwr Ctrl Rng Agg Alg2 Step None:
    Lwr Lim     and Upr Lim     		N/A
    -1 -7.7 -12.3 E -15.7 -24.3 G
    TX Pwr Ctrl Rng Agg Alg1 Step Dn
    1dB: Lwr Lim     and Upr Lim     		TX Pwr Ctrl Rng Agg Alg1 Step Dn
    2dB: Lwr Lim     and Upr Lim
    0,0,0,0,+1 +5.7 +14.3 B N/A N/A N/A
    TX Pwr Ctrl Rng Agg Alg2 Step Up
    1dB: Lwr Lim     and Upr Lim     		N/A
    0,0,0,0,-1 -5.7 -14.3 C N/A N/A N/A
    TX Pwr Ctrl Rng Agg Alg2 Step Dn
    1dB: Lwr Lim     and Upr Lim     		N/A

    Manual Mode : The following table indicates for which manual test scenarios the pass/fail range settings are applied.

    Manual Mode Pass/Fail Range Settings
    Pass/Fail Range Setting Applicable Manual Test Scenarios
    TX Pwr Ctrl Rng Sngl Step Up
    1dB: Upr Lim     and Lwr Lim     		Stop Power > Start Power
    and Power Control Algorithm = Two or One with Step Size = 1 dB .
    TX Pwr Ctrl Rng Sngl Step Up
    2dB: Upr Lim     and Lwr Lim     		Stop Power > Start Power
    and Power Control Algorithm = One with Step Size = 2 dB .
    TX Pwr Ctrl Rng Sngl Step None:
    Upr Lim     and Lwr Lim

    Start Power = Stop Power
    or Power Control Algorithm = Two .
    TX Pwr Ctrl Rng Sngl Step Dn
    1dB: Upr Lim     and Lwr Lim     		Stop Power < Start Power
    and Power Control Algorithm = Two or One with Step Size = 1 dB .
    TX Pwr Ctrl Rng Sngl Step Dn
    2dB: Upr Lim     and Lwr Lim     		Stop Power < Start Power
    and Power Control Algorithm = One with Step Size = 2 dB .
    TX Pwr Ctrl Rng Agg Alg1 Step Up
    1dB: Upr Lim     and Lwr Lim     		Stop Power > Start Power
    and Power Control Algorithm = One with Step Size = 1 dB .
    TX Pwr Ctrl Rng Agg Alg1 Step Up
    2dB: Upr Lim     and Lwr Lim     		Stop Power > Start Power
    and Power Control Algorithm = One with Step Size = 2 dB .
    TX Pwr Ctrl Rng Agg Alg1 Step Dn
    1dB: Upr Lim     and Lwr Lim     		Stop Power < Start Power
    and Power Control Algorithm = One with Step Size = 1 dB .
    TX Pwr Ctrl Rng Agg Alg1 Step Dn
    2dB: Upr Lim     and Lwr Lim     		Stop Power < Start Power
    and Power Control Algorithm = One with Step Size = 2 dB .
    TX Pwr Ctrl Rng Agg Alg2 Step None:
    Upr Lim     and Lwr Lim

    Start Power = Stop Power
    or Power Control Algorithm = Two .
    TX Pwr Ctrl Rng Agg Alg2 Step Up
    1dB: Upr Lim     and Lwr Lim     		Stop Power > Start Power
    and Power Control Algorithm = Two .
    TX Pwr Ctrl Rng Agg Alg2 Step Dn
    1dB: Upr Lim     and Lwr Lim     		Stop Power < Start Power
    and Power Control Algorithm = Two .

      

  • Trigger Delay

    You can adjust the beginning of the measurement interval for each slot measured using the Trigger Delay setting. This is useful if your UE's output power change in response to TPC commands is delayed. You can then shift the measurement interval to match the delay in the UE's response.

    Note, Trigger Delay should only be set to a non-zero value if your UE's output power response to TPC commands is delayed (i.e. if your UE is not operating properly). If your UE is behaving correctly in the timing of power changes in response to TPC commands, non-zero values of the Trigger Delay setting can cause unspecified results.

  • Measurement Timeout : (see Measurement Timeouts ).

Inner Loop Power Measurement Results

The test set can run a single one of the test segments at a time resulting in pass/fail and trace data that can be accessed via the MUI or RUI.

Pass/Fail and Worst Case Result Boundaries

Which timeslots are evaluated for pass/fail criteria (as specified by Transmitter Power Control Pass/Fail Ranges ) and worst case results are determined as follows:

  • Auto Mode , test segments A, B and C: Pass/fail limit checking and worst case results are determined for the entire range of measured results.
  • Auto Mode , test segments E, F, G and H: Pass/fail limit checking and worst case results are determined for the range of measured results bounded by the Minimum Power Threshold for Test and the Maximum Power Threshold for Test (see Test Thresholds and Tolerances ).
  • Manual Mode : Pass/fail limit checking and worst case results are determined for the range of measured results bounded by Start Power and Stop Power .

Inner Loop Power Measurement Results

  • Overall pass/fail result for the specified test segment: if any timeslot in the test segment does not meet the pass/fail criteria (see Transmitter Power Control Pass/Fail Ranges ), the entire segment test fails.
  • Number of slots: indicates the number of timeslots measured. For test segments E-H, this is not necessarily the same as the number of timeslots used for determining pass/fail and worst case results (see Test Thresholds and Tolerances ).
  • Results associated with each timeslot in which a TPC command was sent by the test set:
    • Slot number: Used as an index to the results reported in each timeslot. Slot 0 is the reference timeslot. Response to the TPC command sequence are from Slot 1.
    • Absolute Pwr (dBm): Indicates mean output power level for the current slot excluding the transient time (25 us from either side of the slot boundary).
    • Relative Pwr (dB): The difference between the mean power in the current slot and the mean power in the previous slot.
    • Rel Pwr 10 TPC (dB): The change in mean power over 10 TPC_cmd groups. (NAN for the first 9 results when in Algorithm 1 mode and NAN for the first 49 results when in Algorithm 2 mode.)
    • P/F: Indicates whether the change in the UE transmit power level is within the range specified by the Transmitter Power Control Pass/Fail Ranges . (Pass/Fail result: 0 = pass, 1 = fail adj TPC_cmds, 2 = fail 10 TPC_cmd groups result, 3 = fail in both adj TPC_cmds and 10 TPC_cmd groups test)
  • Worst case results (closest to failing or farthest from the pass/fail range if it failed).
    • Timeslot number of the worst case adjacent TPC_cmds result in which the worst case relative power for adjacent TPC_cmds is returned.
    • Absolute power level associated with the worst case TPC_cmds timeslot
    • Relative power level for adjacent TPC_cmds associated with the worst case TPC_cmds timeslot
    • Relative power level for 10 TPC_cmd groups associated with the worst case TPC_cmds timeslot
    • Timeslot number of the worst case 10 TPC_cmd groups result in which the worst case relative power for 10 TPC_cmd groups is returned.
    • Absolute power level associated with the worst case 10 TPC_cmd groups timeslot
    • Relative power level for adjacent TPC_cmds associated with the worst case 10 TPC_cmd groups timeslot
    • Relative power level for 10 TPC_cmd groups associated with the worst case 10 TPC_cmd groups timeslot

Inner Loop Power Input Signal Requirements

  • For this measurement the test set's receiver uses autoranging to adjust for the level of the signal being measured; therefore, the expected signal level does not need to be specified during measurement setup.
  • The frequency of the signal being measured must be in the range of 800 MHz to 1000 MHz, 1700 MHz to 1990 MHz, or 2480 MHz to 2580 MHz.
  • The level into the test set's RF IN/OUT connector must be in the range of -61 dBm to +28 dBm, in a 3.84 MHz bandwidth.

Inner Loop Power Measurement Calibration

You must calibrate this measurement using the Calibrate Measurements procedure (see Calibrating the Test Set ).

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