Last updated: January 15, 2009
This section is only applicable to the lab application.
Idle Periods in the Downlink (IPDL) is a feature whereby the Node-B intermittently switches off its transmitter for all channels (common and dedicated) for short periods of time, known as idle periods. This gives the UE an opportunity to make more accurate measurements of neighboring cells that are required for applications such as position determination. IPDL is different from compressed mode in that with IPDL the system makes no attempt to avoid data loss.3GPP TS 25.214 Section 8, "Idle periods for IPDL location method" is the primary 3GPP specification reference for this functionality. This defines an equation by which the 8960 can determine when the idle periods will occur and their length (which is either 5 or 10 CPICH symbols). This equation includes a pseudo random number generator to introduce irregularities in the idle period spacing, however the nature of the random number generator is predictable and thus the start position of the idle periods can always be unambiguously determined.
There are two modes in which IPDL can operate, continuous or burst. The test set supports both of these modes. Additional parameters allow you to control the length and frequency of the bursts. Continuous mode is essentially a single burst that spans the full 4096 SFN cycle.
In the test set, IPDL is a layer 1 only feature. There is no associated Layer 3 signaling to inform the UE about when the idle periods will occur. Support for the Layer 3 signaling is provided independently through the SIB15.s message support You must ensure that the contents of the SIB15.x messages match the test set's Layer 1 configuration.
You can start and stop the idle periods at any time (including on a call). However the parameters of the idle periods can only be changed when IPDL is not active. When IPDL is active the test set reduces its transmit power by switching off modulation during the idle periods.
IPDL is supported in both Active Cell and FDD Test Mode Cell Operating Modes.
This section is only applicable to the lab application.
This parameter controls whether IPDL is active or not.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink[:STATe]
This parameter sets the IPDL mode, either Burst or Continuous.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:STATus
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
This parameter sets the spacing between idle periods.
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:IPSPacing
This parameter defines a static offset used in the calculation of idle period start positions (used to synchronize idle periods across sectors).
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:IPOFfset
This parameter controls the length of the idle periods and is specified in CPICH symbols.
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:IPLength
This parameter sets the seed for the random number generator used when calculating the idle period start positions.
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:RNGenerator:SEED
This parameter sets the start of the first burst (start system frame number (SFN) = 256 * Burst Start).
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:BSTart[:FRAMes256]
This parameter sets the number of idle periods in a burst.
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:BLENgth[:PERiods]
This parameter influences the frequency of bursts within the SFN cycle (it defines the number of radio frames * 256 between bursts).
This setting cannot be changed while IPDL is active. If you attempt to change this setting while the IPDL State is On then the test set will reject the change and an error will be reported.
GPIB command: CALL[:CELL]:CONTrol:IPDownlink:BFRequency[:FRAMes256]