In LTE, UE measurements related to RSRP, RSRQ, and SNR associated with CRS (Cell-specific Reference Signal) are performed. 5G NR uses SS (Synchronization Signal) and CSI (Channel State Information) instead of CRS, so 3GPP has established new definitions for UE measurements, some of which will be discussed below.
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For FR-1, the reference point for measurements should be the UE’s antenna connector.
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For FR-2, measurements should be based on the combined signal from the antenna elements corresponding to the given receiver branch.
SS-RSRP: SS-RSRP stands for Synchronization Signal Reference Signal Received Power. It is defined as the linear average of the power contribution (in watts) of the resource elements carrying the SSS. The measurement time resources for SS-RSRP are limited to the duration of the SS/PBCH block measurement time configuration (SMTC) window.
For the determination of SS-RSRP, the demodulation reference signal of PBCH can be used, and if indicated by higher layers, CSI RS can also be used in addition to SSS. The SS-RSRP of the demodulation reference signal using PBCH or CSI reference signals should be measured by linearly averaging the power contributions of the resource elements carrying the corresponding reference signals, taking into account the power scaling of the reference signals. This measurement applies to the following situations:
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RRC_CONNECTED intra-frequency
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RRC_IDLE intra-frequency
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RRC_IDLE inter-frequency
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RRC_INACTIVE intra-frequency
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RRC_INACTIVE inter-frequency
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
CSI-RSRP: CSI-RSRP stands for CSI Reference Signal Received Power. It is defined as the linear average of the power contribution (in watts) of the resource elements configured for RSRP measurement within the measurement frequency bandwidth in the configured CSI-RS occasion. For the determination of CSI-RSRP, the CSI reference signal transmitted on antenna port 3000 should be used; if CSI_RSRP is used for L1-RSRP, the CSI reference signal transmitted on antenna ports 3000 and 3001 can be used.
For intra-frequency CSI-RSRP measurements, if measurement gaps are not configured, it is not expected that the UE will measure CSI-RS resources outside the active downlink bandwidth. CSI-RSRP measurements apply to the following situations:
If CSI-RSRP is used for L1-RSRP, then RRC_CONNECTED frame intra-frequency. Otherwise
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RRC_CONNECTED intra-frequency,
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RRC_CONNECTED inter-frequency
NR-RSSI: NR-RSSI stands for NR Carrier Received Signal Strength Indicator, which includes the total received power (in watts) observed only in certain OFDM symbols of the measurement time resources, in the measurement bandwidth, across N resource blocks from all sources, including serving and non-serving cells, adjacent channel interference, thermal noise, etc. The measurement time resources for NR-RSSI are limited to the duration of the SS/PBCH block measurement time configuration (SMTC) window.
For frequency intra-measurements, NR-RSSI should be measured using the timing reference corresponding to the serving cell in the frequency layer.
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For frequency inter-measurements, NR-RSSI should be measured using the timing reference corresponding to any cell in the target frequency layer.
CSI-RSSI: CSI-RSSI stands for CSI Received Signal Strength Indicator, which includes the total received power (in watts) observed only in the OFDM symbols of the measurement time resources, in the measurement bandwidth, across N resource blocks from all sources, including serving and non-serving cells, adjacent channel interference, thermal noise, etc. The measurement time resources for CSI-RSSI correspond to the OFDM symbols containing the configured CSI-RS occasion.
SS-RSRQ: SS-RSRQ stands for Secondary Synchronization Signal Reference Signal Received Quality. It is defined as the ratio of N×SS-RSRP to NR Carrier RSSI, where N is the number of resource blocks in the NR Carrier RSSI measurement bandwidth. The measurements of the numerator and denominator should be performed on the same set of resource blocks. SS-RSRQ measurements apply to the following situations:
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RRC_IDLE intra-frequency
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RRC_IDLE inter-frequency
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RRC_INACTIVE intra-frequency
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RRC_INACTIVE inter-frequency
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
CSI-RSRQ: Defined as the ratio of N×CSI-RSRP to CSI-RSSI, where N is the number of resource blocks in the RSSI measurement bandwidth. The measurements of the numerator and denominator should be performed on the same set of resource blocks. CSI-RSRQ measurements apply to the following situations:
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
SS-SINR: SS-SINR stands for SS Signal to Interference plus Noise Ratio. It is defined as the linear average of the power contribution (in watts) of the resource elements carrying SSS divided by the linear average of the noise and interference power contributions (in watts) on the same frequency bandwidth carrying SSS resource elements. SS-SINR measurements apply to the following situations:
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
CSI-SINR: CSI-SINR stands for CSI Signal to Interference plus Noise Ratio. It is defined as the linear average of the power contribution (in watts) of the resource elements carrying the CSI reference signal divided by the linear average of the noise and interference power contributions (in watts) on the same frequency bandwidth carrying the CSI reference signal. SS-SINR measurements apply to the following situations:
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
References:
3GPP TS 38.215: 5G NR; Physical Layer Measurements
3GPP TS 38.213: 5G NR; Physical Layer Procedures for Control Channels
3GPP TS 38.214: 5G NR; Physical Layer Procedures for Data Channels
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