EDGE Dynamic Power (EDP) Measurement

How is an EDGE Dynamic Power Measurement Made?

Mobile stations that support EDGE maintain GMSK, the modulation scheme used for GSM and GPRS, for low data rates. EDGE also supports 8PSK, a modulation scheme that extends the raw data rates of GMSK. The test set's EDP measurement provides a mechanism to quickly obtain power measurements of either 8PSK or GMSK modulated signals from a mobile station.

For GMSK modulated bursts generated from an EDGE mobile station, burst power is the only measurement method available in the test set. Burst power determines the power of the burst without any compensation for data content. For 8PSK modulated bursts generated from an EDGE mobile station, the test set offers the following measurement methods: burst power, variable Estimated Carrier Power (ECP), or fixed ECP. ECP is an approximation of the long-term average burst power. Variable ECP assumes a random data pattern is used for each burst and so determines an estimated carrier power compensation factor for each burst in the ramp segment individually. To use the fixed ECP to determine each burst power all bursts in the ramp segment must contain the same data pattern. This results in a faster measurement time because it is only necessary to determine the estimated carrier power compensation factor for the highest power burst in the ramp, which is then applied to each burst in the ramp segment. Variable ECP or Fixed ECP values for each burst in a ramp segment are determined by a single burst. For multi-segment ramps, the same measurement method is used for all segments. Multi-segment ramps are concatenations of single segment ramps, see Figure 1 .

The EDGE Dynamic Power (EDP) measurement must range the measurement receiver individually for each burst in a ramp segment. The receiver's expected power level for the first burst in a ramp segment can be either manually specified or can use the test set's expected power setting. The expected power level for subsequent group bursts are determined by adding the step size, or Expected Maximum Difference (EMD), to the measured power of the final burst in the previous burst group. Figure 1 illustrates how the EMD is used to find all subsequent group burst power levels after the first group. The EMD parameter may be a positive or negative value to facilitate increasing or decreasing power ramps, and can be set separately for each segment in a multi-segment ramp.

When the Initial Power State parameter is set to 1 or ON, the same expected power setting is used for the first burst in all ramp segments. The value used for the initial power depends on the state of the Expected Power Control. If the Expected Power Control parameter is set to Auto, the MS TX Level Burst 1 power level is used. If the Expected Power Control parameter is set to Manual, the expected power that is used is the power level setting for burst 1 that the test set's receiver is expecting to see. When the initial power state is set to OFF, the initial power values for each ramp segment can be set with the Initial Power Value parameter. For more information on the Initial Power State parameter see SETup:EDPower:INITial:POWer:AUTO .

Figure 1

Series of mobile station generated bursts at consecutive power levels.

The bursts drawn with solid lines of Figure 1 depicts what a typical single power ramp segment looks like. The dashed lines are portions of other segments of the multi-segment power ramp. Figure 1 is a single ramp segment with a burst count of 15 and a group count of 5. The number of segments measured in a multi-segment power ramp are configured with the Ramp Segment Count parameter. The test set measures the number of bursts in a ramp segment given by the Ramp Segment Burst Count parameter.The number of bursts at each expected power level is configured with the Ramp Segment Group Count parameter.

EDP measurement results are returned in blocks, or ranges, of 100 values. For example, if the burst count is 150, range 1 will return 100 power measurement results, range 2 will return 50 power measurement results, and ranges 3-10 will return a NaN because there are no result in the range. The same number of integrity values are returned as the burst power measurements. Range 1 will contain 100 integrity values and power measurements, range 2 will contain 50 integrity values and power measurements, and ranges 3-10 will contain the value 1, indicating no results are available for the specified range.

EDGE Dynamic Power Measurement Configurable Parameters

Parameter	GPIB Command
Trigger Arm	INITiate:<measurement mnemonic>[:ON] using EDPower as the <measurement mnemonic> READ:EDPower[:ALL][:RANGe1|RANGe2|RANGe3|RANGe4|RANGe5|RANGe6|RANGe7|RANGe8|RANGe9|RANGe10]? SETup:EDPower:CONTinuous
Timeout State and Time	SETup:EDPower:TIMeout[:STIMe] SETup:EDPower:TIMeout:TIME SETup:EDPower:TIMeout:STATe
Expected Maximum Time Interval State and Value	SETup:EDPower:EMTInterval[:STIMe] SETup:EDPower:EMTInterval:STATe SETup:EDPower:EMTInterval:TIME
Ramp Segment Burst Count	SETup:EDPower:COUNt:NUMBer
Ramp Segment Group Count	SETup:EDPower:COUNt:GROup:SIZE
Ramp Segment Expected Maximum Difference	SETup:EDPower:EMDifference
Ramp Segment Initial Power	SETup:EDPower:INITial:POWer
Ramp Segment Initial Power State	SETup:EDPower:INITial:POWer:AUTO
Ramp Segment Count	SETup:EDPower:COUNt:RSEGment
Measurement Method	SETup:EDPower:METHod

Input Signal Required

The input signal for the EDGE Dynamic Power measurement must be a normal burst.

The EDGE Dynamic Power measurement completes and meets its measurement accuracy specifications when the signal meets the following input signal conditions.

• Input signal level is -15dBm to +37 dBm for GMSK, and -15dBm to +33dBm for 8PSK.
• Input signal level is within +/- 3 dB of the expected input level for the first burs and +/-2 dB for all subsequent burst in the ramp segment.
• The frequency setting tolerance is +/- 50 kHz for signals with an RMS EVM value of 7.5% or less.
• The temperature range is 20º C to 50º C.
• After transmitting each ramp or multi-segment ramp, the mobile station must wait a short period before transmitting the next ramp or multi-segment ramp. This period is calculated as 4.62 ms times the number of bursts in the ramp or multi-segment ramp when using the variable ECP method, or 2.31ms times the number of bursts when using the fixed ECP or burst power measurement methods.

EDGE Dynamic Power Measurement Results

• Integrity Indicator for each burst measured
• Power Level for each burst measured

The EDGE Dynamic Power measurement does not use the multi-measurement state parameter, and so does not return minimum, maximum, and standard deviation values. Instead, specify the number of bursts to measure using the Ramp Segment Burst Count parameter (see SETup:EDPower:COUNt:NUMBer ). A single measurement returns the integrity indicator and power level for every burst measured. For example, if you set the number of bursts to 15, the returned comma-separated list contains 15 integrity values followed by 15 corresponding measurement values.

Trigger Source

The trigger source that EDGE Dynamic Power measurement supports is RF Rise.

Operating Considerations

• This measurement is a test mode only measurement, so it is not available when the operating mode is Active Cell. The EDGE Dynamic Power Measurement can measure both GMSK and 8PSK bursts in the EGPRS test modes, as well as GMSK bursts in the GSM and GPRS test modes. For more information on test modes, see Test Mode Operating Modes .

• Only normal bursts in a single slot configuration are supported and all bursts in the ramp must be at the same frequency.

• Initiating this measurement automatically aborts and closes any other measurement running at the time.

• Set up parameters and measurement results for this measurement are only accessible using the GPIB interface.

Related Topics

Programming an EDGE Dynamic Power Measurement

SETup:EDPower

FETCh:EDPower

Test Adherence to Standards