Last updated: 2014-11-28
Waveform Quality Measurement Description
Waveform Quality Measurement Parameters
Waveform Quality Measurement Results
The waveform quality measurement is used to test the following measurements as defined in the test standard 3GPP TS 34.122: EVM, Frequency Stability and Peak Code Domain Error.
The Error Vector Magnitude (EVM) is a measure of the difference between the measured waveform and the theoretical modulated waveform (the error vector). Both waveforms pass through a matched Root Raised Cosine filter with bandwidth 1.28 MHz and roll-off of 022. Both waveforms are then further modified by selecting the frequency, absolute phase, absolute amplitude and chip clock timing so as to minimize the error vector. The EVM result is defined as the square root of the ratio of the mean error vector power to the mean reference signal power expressed as a %.
The waveform quality measurement in the test set compares the received signal's IQ modulation characteristics to an ideal signal, as defined in 3GPP TS 34.121.
According to the standard, the Error Vector Magnitude shall not exceed 17.5 % for UE output power more than -20dBm and Power control step size is 1dB.
The frequency stability is the difference of the modulated carrier frequency between the RF transmission from the UE and the RF transmission from the test set.
According to the standard, The UE frequency stability, observed over a period of one timeslot, shall be within ±0.1 ppm compared to signals received from the test set.
The code domain error is computed by projecting the error vector power onto the code domain at a specific spreading factor. The error power for each code is defined as the ratio to the mean power of the projection onto the code, to the mean power of the composite reference waveform expressed in dB. And the Peak Code Domain Error is defined as the maximum value for Code Domain Error.
According to the standard, the peak code domain error shall not exceed -21dB at spreading factor 16 for 1,28 Mcps TDD Option.
Multi-Measurement Count: see Multi-Measurement Count
Trigger Arm: see Trigger Arm
Trigger Source: see Trigger Source
Trigger Delay: see Trigger Delay
Time Slot to Measure: see Time Slot to Measure
Manual Power Range Offset: see Manual Power Range Offset
Measurement Timeout: see Measurement Timeout
The following result items can be derived after the waveform quality measurement.
Integrity Indicator: see Integrity Indicator
EVM: Error Vector Magnitude (in % RMS), see FETCh:TWQuality:EVM[:AVERage]?
Peak EVM (maximum chip EVM, in %) - available through GPIB query only, see FETCh:TWQuality:EVM:PEAK[:AVERage]?
Frequency Error (in Hz), see FETCh:TWQuality:FERRor[:AVERage]?
Origin Offset (in dB), see FETCh:TWQuality:OOFFset[:AVERage]?
Phase Error (in degrees), see FETCh:TWQuality:PERRor[:AVERage]?
Magnitude Error (in %), see FETCh:TWQuality:MERRor[:AVERage]?
Time Error (in chips)
Time error is a measure of the timing error of the UE's transmission relative to the frame clock, see FETCh:TWQuality:TERRor[:AVERage]?
Peak Code Domain Error (PCDE) (Maximum PCDE, in dB)
Peak Code Domain Error (in dB) and the code channel at which it occurs (C ch,Spreading Factor,Code Number ), see FETCh:TWQuality:PCERror[:ALL]?
The measured signal level is expected to be within 9 dB of the expected power.
Input signal level into the test set's RF IN/OUT connector is between -25 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.
GPIB Commands: SETup:TWQuality, FETCh:TWQuality