Setting Reverse Closed Loop Power Control

Setting Reverse Closed Loop Power Control

Last updated: November 22, 2010

The reverse closed loop power control parameter determines what power control bits are sent to the mobile station to cause the mobile station increase or decrease its output power. The test set provides two kinds of closed loop power control (CLPC):

Reverse CLPC Steady-state Modes

The test set normally uses reverse CLPC steady-state modes to control the mobile station output power unless you initiate the reverse CLPC transient modes (see Reverse CLPC Transient Modes ).

The reverse CLPC steady-state modes as listed in table below are accessed from the Rvs Power Ctrol ( F7 ) on the Call Parms 2 of 4 menu. See How Do I Change Call Parameters? for front panel operation. For related GPIB commands, see CALL[:CELL[1]]:CLPControl:REVerse:MODE<[:SELected]|:TA2000> .

Reverse CLPC steady-state Modes
Setting Description
Active Bits The test set actively determines if the mobile station is transmitting at a power level that is too high or too low (based on the expected mobile power, see Automatic Receiver Control ), and responds by sending the appropriate up or down power control bit.
Alternating Bits The test set sends alternating "up" (0) and "down" (1) power control bits to the mobile station regardless of its output power.
All Up Bits
The test set sends continuous "up" power control bits (0's) to the mobile station regardless of its output power.
All Down Bits The test set sends continuous "down" power control bits (1's) to the mobile station regardless of its output power.
Alternating 20 Bits (for lab application only) The test set sends a periodic sequence of 20 up power control bits followed by 20 down power control bits to the mobile station regardless of its output power.

   
IMPORTANT
In order for the test set to successfully decode signalling from the mobile station, the signal level into the test set's RF IN/OUT connector must be within 9 dB of the expected input power based on the power transmitted from the test set and open loop estimate (see Automatic Receiver Control ). When reverse CLPC is set to All Up Bits or All Down Bits, the mobile station's power may not be within the required range, and all signalling will fail. Before attempting any signalling between the test set and the mobile station, you must either set Reverse Closed Loop Power to Active Bits, or manually range the Receiver Power to the level that the mobile station is currently transmitting based on the reverse CLPC setting (see Manual Receiver Control in Active Cell Operating Mode ).
   

Reverse CLPC Transient Modes

The reverse CLPC steady-state modes (see Reverse CLPC Steady-state Modes ) can be temporarily interrupted in order to insert a number of the user-defined power control bits as specified by the Rvs Power Ctrl Transient Parm ( F8 ) on the Call Parms 4 of 4 menu. This is called reverse CLPC transient. The test set returns to the reverse CLPC steady-state modes after the completion of the reverse CLPC transient.

For example, if the Transient Mode is set to Down (see Setting Reverse CLPC Transient Parameters ) and the Rvs Power Ctrol ( F7 ) is set to All Up bits (see Reverse CLPC Steady-state Modes ), the number of down power control bits as specified by the Transient Number of Steps field will be sent to the mobile station when the F7 ( Start Rvs Power Ctrl Transient ) is pressed. After the completion of transient transmission, the test set will then resume sending continuous up power control bits.

   
NOTE
For lab application, the reverse CLPC transient settings for cell 1 also impact the Cell 2 closed loop power control if the Cell2 reverse CLPC is set to track Cell1 bits ( CALL:CELL2:CLPControl:REVerse:MODE ).
   

Setting Reverse CLPC Transient Parameters

The reverse CLPC transient parameters are accessed from the Rvs Power Ctrl Transient Parm ( F8 ) on the Call Parms 4 of 4 menu. See How Do I Change Call Parameters? .

  • Transient Mode ( CALL[:CELL[1]]:CLPControl:REVerse:TRANsient:MODE ). specifies the number and direction of the ramp(s) of the reverse CLPC transient.
    • Up indicates one up ramp of power control transient. When F7 ( Start Rvs Power Ctrl Transient) is pressed, the test set will send the number of "up" power control bits (0's) as specified by the Transient Number of Steps to the mobile station on the forward power control subchannel.
    • Down indicates one down ramp of power control transient. When F7 ( Start Rvs Power Ctrl Transient) is pressed, the test set will send the number of "down" power control bits (1's) as specified by the Transient Number of Steps to the mobile station on the forward power control subchannel.
    • Up-Down-Up indicates three ramps of power control transient (one up ramp, followed by one down ramp and then followed by one up ramp). When F7 ( Start Rvs Power Ctrl Transient) is pressed, the test set will send the number of "up" power control bits (0's) as specified by the Transient Number of Steps , then followed by the same number of power down bits (1's) and then followed by the same number of power up bits (0's) again to the mobile station.
  • Transient Number of Steps ( CALL[:CELL[1]]:CLPControl:REVerse:TRANsient:SPRamp ). specifies the number of power control bits that will be inserted into each ramp (slope) of the reverse CLPC transient. The Pwr Ctrl Size ( F8 on Call Parms 2 of 4 ) is used to specify how much the mobile station increases or decreases its power per each received power control bit (see CALL[:CELL[1]]:CLPControl:REVerse:[:NORMal]:STEP ). If the Transient Mode is set to Up_Down_Up then the total number of power control bits during reverse CLPC transient will be three times the value of this setting.

Starting the Reverse CLPC Transient

When a forward traffic/fundamental channel (forward power control subchannel) is present (for example, during a call connection), pressing the F7 ( Start Rvs Power Ctrl Transient) or sending the CALL[:CELL[1]]:CLPControl:REVerse:TRANsient:STARt causes a request for transmission of a power control transient as specified by the Rvs Power Ctrl Transient Parm ( F8 ).

   
NOTE
If any of the measurements (such as Handoff Waveform Quality, Waveform Quality + Code Domain, Code Channel Time/Phase Error, Time Response of Open Loop Power Control and Tx Dynamic Power) are running at the time the power control transient transmission starts the measurement will be closed and its operation aborted.

None of the measurements listed above will be able to start (become initiated) while the transient transmission is in progress.
   

During the power control transient,

  • the test set will emit a trigger signal (a positive TTL pulse with a width of about 1.25 ms) coincident with the transmission of the first power control bit in each transient. This trigger will be available on the TRIG OUT port of the test set's rear panel if the Ext Trigger ( F4 on the Gen Info menu) is set to FDEPendent (see Setting External Trigger ). This trigger can be used for the synchronization of external measurement instrument or trigger the test set's internal Spectrum Monitor instrument (see Example Usage of Reverse CLPC Transient Mode ).
  • the test set can accept and process any command immediately after starting a power control transient (while the transient is still being transmitted). However, The reverse CLPC transient is not guaranteed to be completed when the next user command is processed.
  • the test set can accept up to two reverse CLPC transient start requests in addition to the one currently being transmitted (total of 3). When a currently transmitting transient has completed the next transient in the queue will be transmitted.
  • the test set returns to the reverse CLPC steady-state mode after the completion of the transient transmission.
  • you can change the reverse CLPC steady-state mode while a transient is being transmitted. The newly selected reverse CLPC steady-state mode will be used when the transient (and any other queued transients) are completely transmitted.
  • if the forward traffic/fundamental channel (forward power control subchannel) is lost while transmitting a transient then the current power control transient will not be completely transmitted, and any enqueued transient requests will be removed from the queue and will not be transmitted.

   
NOTE
If there is no forward traffic/fundamental channel present (no power control subchannel), pressing F7 ( Start Rvs Power Ctrl Transient) does nothing (no error, no trigger).
   

Reverse Power Control Setup

In order to enhance the capability of the existing CDMA2000 networks, 1x advanced applies slower power control which cuts excess power in Power Control Sub Channel. You can setup the reverse power control by pressing the Reverse Power Control Setup ( F9 ) on Call Parms 2 of 4 menu. There are two parameters related to reverse power control.

  • Reverse Power Control Mode

    This parameter determines what kind of the mode of reverse power control is used on the test set.

    • 200 to 400 bps: When set to 200 to 400 bps , the test set transmits power control bits in PCGs 1, 3, 5, 7, 9, 11, 13, and 15.
      • If smart blanking is disabled on R-FCH (see Smart blanking ), all power control bits received shall be considered valid, so the RPC rate is 400bps.
      • If smart blanking is enabled on R-FCH, the reverse pilot channel is gated and only power control bits received in PCGs 1, 5, 9, and 13 shall be considered valid when the mobile station transmits zero-rate frame. All power control bits received shall be considered valid when the mobile station transmits a non-zero rate frame.

      So RPC rate is dynamically changed from 200 bps to 400 bps.

    • 200 bps: When set to 200 bps , the test set transmits power control bits in PCGs 1, 5, 9, and 13.

    GPIB Command: CALL[:CELL[1]]:CLPControl:REVerse:PCMode

  • Power Control Step Size

    GPIB Command: CALL[:CELL[1]]:CLPControl:REVerse:SLOW:STEP