Section: 6.5.2.1 Error Vector Magnitude
Content: The Error Vector Magnitude is a measure of the difference between the reference waveform and the measured waveform. This difference is called the error vector. Before calculating the EVM the measured waveform is corrected by the sample timing offset and RF frequency offset. Then the carrier leakage shall be removed from the measured waveform before calculating the EVM. The measured waveform is further modified by selecting the absolute phase and absolute amplitude of the Tx chain. The EVM result is defined after the front-end IDFT as the square root of the ratio of the mean error vector power to the mean reference power expressed as a %. The basic EVM measurement interval in the time domain is one preamble sequence for the PRACH, and as specified in Table 6.5.2.1-1 for the PUCCH and PUSCH in the time domain. When the PUSCH or PUCCH transmission slot or subslot is shortened due to multiplexing with SRS, the EVM measurement interval is reduced by one symbol, accordingly. Likewise, when the PUSCH starting position is modified or when second last symbol is the ending symbol of the PUSCH subframe for Frame Structure Type 3, the EVM measurement interval is reduced accordingly. The PUSCH or PUCCH EVM measurement interval is also reduced when the mean power, modulation or allocation between slots or subslots is expected to change. In the case of PUSCH transmission, the measurement interval is reduced by a time interval equal to the sum of 5 μs and the applicable exclusion period defined in subclause 6.3.4, adjacent to the boundary where the power change is expected to occur. The PUSCH exclusion period is applied to the signal obtained after the front-end IDFT. In the case of PUCCH transmission with power change, the PUCCH EVM measurement interval is reduced by one symbol adjacent to the boundary where the power change is expected to occur. Table 6.5.2.1-1: Measurement interval for EVM