What is EVM?

EVM stands for Error Vector Magnitude. According to 3GPP TS 36.101 (eNB Rx) and 36.104 (UE Rx) section 6.5.2, the EVM measures the difference between the reference waveform and the measured waveform. The EVM is calculated after the FFT (UE Rx) or IDFT (eNB Rx) as the square root of the ratio of the mean vector power to the mean reference power given in %. The EVM formula is given in TS 36.101, annex F2 (eNB Rx) and TS 36.104, annex E2 (UE Rx).

How a UE knows which PDCCH part to listen in LTE?

UE knows which PDCCH part to listen from the RRC configuration (for dedicated resources). For the initial connection and broadcasted info the UE uses predefined PDCCH configuration and the one obtained from System Information.