The terminal (UE) performs wireless measurements of CRS signal RSRP, RSRQ, and SNR for the serving cell in 4G (LTE). Since the 5G (NR) network uses SS (Synchronous) and CSI (Channel State Information) signals, 3GPP has redefined the measurements for the terminal (UE), which include RSRP, RSSI, RSRQ, and SINR. Where:
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For FR-1, the measurement reference point is the terminal (UE) antenna connector;
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For FR-2, measurements are based on signals from the corresponding antenna element combination of a given receiver branch.
1. SS-RSRP: SS-RSRP is the signal reference power received from the synchronization signal, defined as the linear average of the power contribution of SSS resource elements (in watts). The measurement time resources for SS-RSRP are limited to the SS/PBCH block configuration time (SMTC) window. The PBCH demodulation reference signal determined for SS-RSRP can also use CSI RS in addition to high-level indications. When using PBCH or CSI reference signals, SS-RSRP should be measured by linear averaging the power contributions of the corresponding reference signal resource elements, taking into account the reference signal power scaling. The measurement is applicable to the following scenarios:
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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
2. CSI-RSRP: CSI-RSRP is defined as the linear average of the power contributions (in watts) of resource elements for the CSI reference signal. The CSI-RS resource elements used for RSRP measurements should be configured within its frequency band, typically transmitted on antenna port 3000; if CSI_RSRP is an L1 layer measurement, it can be transmitted on antenna ports 3000 and 3001.
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The physical and logical ports of 5G antennas
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5G (NR) network reference signal CSI-RS structure
For co-frequency CSI-RSRP measurements, if measurement gaps are not configured, the UE is not expected to measure CSI-RS resources outside the active downlink bandwidth. CSI-RSRP measurements are applicable in the following cases:
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If CSI-RSRP is used for L1-RSRP, RRC_CONNECTED intra-frequency. Otherwise,
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RRC_CONNECTED intra-frequency,
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RRC_CONNECTED inter-frequency
3. NR-RSSI: NR-RSSI represents the NR carrier received signal strength indicator, which includes the linear average of the total received power (in watts) observed only during certain OFDM symbols in the measurement time resources, exceeding N resource blocks from all sources in the measurement bandwidth, including co-channel serving and non-serving cells, adjacent channel interference, thermal noise, etc. The NR carrier RSSI measurement time resources are limited to the SS/PBCH block measurement time configuration (SMTC) window duration.
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For co-frequency measurements, NR carrier RSSI is measured using timing references corresponding to the serving cell in the frequency layer;
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For inter-frequency measurements, NR carrier RSSI uses timing references corresponding to any cell in the target frequency layer for measurement.
4. CSI-RSSI: CSI-RSSI represents the CSI received signal strength indicator, which includes the linear average of the total received power (in watts) observed only in the measurement time resources OFDM symbols, exceeding N resource blocks from all sources in the measurement bandwidth, including co-channel serving and non-serving cells, adjacent channel interference, thermal noise, etc. The CSI-RSSI measurement time corresponds to the OFDM symbols containing the configured CSI-RS.
5. SS-RSRQ: SS-RSRQ represents the secondary synchronization signal reference signal quality. It is defined as the ratio of N×SS-RSRP/NR carrier RSSI, where N is the number of resource blocks in the NR carrier RSSI measurement bandwidth; measurements in the numerator and denominator should be conducted on the same set of resource blocks, applicable for:
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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
6. 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; measurements in the numerator and denominator should be conducted on the same set of resource blocks. CSI-RSRQ measurements are applicable in the following situations:
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
7. SS-SINR: SS-SINR represents the SS signal-to-noise and interference ratio, defined as the linear average of the power contributions (in watts) of the SSS resource elements divided by the linear average of the noise and interference power contributions (in watts) carrying the SSS resource elements in the same frequency bandwidth. SS-SINR measurements are applicable for:
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency
8. CSI-SINR: CSI-SINR represents the CSI signal-to-noise ratio, defined as the linear average of the power contributions (in watts) of the CSI reference signal resource elements divided by the linear average of noise and the interference power contributions (in watts) on the CSI reference signal resource elements in the same frequency bandwidth. Measurements are applicable for:
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RRC_CONNECTED intra-frequency
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RRC_CONNECTED inter-frequency