10 Modulation accuracy
25.1063GPPRelease 17TSUTRA repeater radio transmission and reception
10.1 Error Vector Magnitude
The modulation accuracy is defined by the Error Vector Magnitude (EVM), which is a measure of the difference between the theoretical waveform and a modified version of the measured waveform. This difference is called the error vector. The measured waveform is modified by first passing it through a matched root raised cosine filter with bandwidth 3.84 MHz and roll-off =0.22. The waveform is then further modified by selecting the frequency, absolute phase, absolute amplitude and chip clock timing so as to minimise the error vector. The EVM result is defined as root of the ratio of the mean error vector power to the mean reference signal power expressed as a %.
The measurement interval is one power control group (timeslot). The repeater shall operate with an ideal WCDMA signal in the pass band of the repeater at a level, which produce the maximum rated output power per channel, as specified by the manufacturer.
10.1.1 Minimum requirement
The Error Vector Magnitude shall not be worse than 12,5 %.
10.2 Peak code domain error
The peak code domain error is computed by projecting the power of the error vector (as defined in subclause 10.1) onto the code domain at a specified spreading factor. The code domain error for every code in the domain is defined as the ratio of the mean power of the projection onto that code, to the mean power of the composite reference waveform. This ratio is expressed in dB. The peak code domain error is defined as the maximum value for the code domain error for all codes. The measurement interval is one power control group (timeslot).
10.2.1 Minimum requirement
The peak code domain error shall not exceed -35 dB at spreading factor 256.
10.3 Relative Code Domain Error (RCDE) for 64QAM modulation
The Relative Code Domain Error is computed by projecting the error vector (as defined in 10.1) onto the code domain at a specified spreading factor. Only the active code channels in the composite reference waveform are considered for this requirement. The Relative Code Domain Error for every active code is defined as the ratio of the mean power of the error projection onto that code, to the mean power of the active code in the composite reference waveform. This ratio is expressed in dB. The measurement interval is one frame.
The requirement for Relative Code Domain Error is only applicable for Repeater supporting 64QAM modulated codes.
10.3.1 Minimum requirement
The average Relative Code Domain Error for 64QAM modulated codes shall not exceed -21 dB at spreading factor 16.