Description
CSI-RSRP is a Layer 1 measurement defined in 3GPP specifications 38.214 and 38.215 for New Radio (NR). It represents the linear average over the power contributions of the resource elements that carry CSI reference signals within the considered measurement frequency bandwidth. Unlike SS-RSRP which measures synchronization signal blocks, CSI-RSRP specifically measures reference signals that are configured for channel state information acquisition, enabling more precise beam-specific measurements.
The measurement procedure involves the UE measuring the received power of configured CSI-RS resources, which can be transmitted in different spatial directions (beams) from the gNB. The UE performs power measurement on the designated CSI-RS resource elements, applying appropriate filtering and averaging as specified. The measurement bandwidth can be configured per CSI-RS resource, allowing flexible measurement granularity. CSI-RSRP measurements are reported to the network through Layer 1 or Layer 3 reporting mechanisms, supporting both periodic and event-triggered reporting.
Architecturally, CSI-RSRP operates within the physical layer measurement framework where the UE's physical layer processes the received CSI-RS symbols, extracts the reference signal sequences, and computes the received power. The measurement accounts for antenna port-specific configurations, supporting measurements from multiple transmit antenna ports. Key components include the CSI-RS resource configuration (defining time-frequency patterns), measurement timing configuration, and reporting configurations that determine when and how measurements are reported to higher layers.
In the network operation, CSI-RSRP serves multiple critical functions. For beam management, it enables the gNB to determine the best transmit/receive beam pairs by comparing CSI-RSRP measurements from different CSI-RS resources transmitted on different beams. For mobility, it provides beam-specific signal quality measurements that complement cell-level measurements, enabling more accurate handover decisions in beamformed networks. For link adaptation, it helps estimate the channel quality for specific transmission configurations, supporting MIMO layer selection and modulation and coding scheme (MCS) adaptation.
Purpose & Motivation
CSI-RSRP was introduced in 5G NR Release 15 to address the limitations of existing reference signal measurements in beamformed systems. Previous LTE systems primarily used CRS (Cell-specific Reference Signal) based RSRP measurements, which were broadcast over the entire cell coverage area. However, in 5G's massive MIMO deployments with beamforming, broadcast reference signals cannot provide accurate beam-specific channel quality information needed for optimal beam management and mobility.
The technology solves the problem of accurately measuring signal strength for specific beamformed transmissions. In beamforming scenarios, different beams have different coverage patterns and signal qualities, requiring beam-specific measurements for effective beam selection and handover. CSI-RSRP enables precise measurement of the channel quality experienced by UE-specific or beam-specific reference signals, which is essential for beam management procedures including beam sweeping, beam measurement, and beam reporting.
Historical context shows that earlier systems lacked beam-specific measurement capabilities. LTE's RSRP measurements were cell-wide and didn't support beam-level granularity. The introduction of CSI-RSRP in 5G NR was motivated by the need to support advanced beam management features, massive MIMO operations, and millimeter wave deployments where beamforming is essential for coverage and capacity. It addresses the limitation of SS-RSRP which, while useful for initial access, doesn't provide the beam-specific accuracy needed for ongoing beam management and mobility in dense beamformed networks.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (75 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the specification for CSI-RSRP was refined, including corrections to the aperiodic CSI-RS triggering procedure to handle different numerologies between the PDCCH and the CSI-RS. Furthermore, corrections were made to the CSI-RS configuration details as documented in the technical specifications. These foundational clarifications ensured accurate power measurement assumptions, such as the defined ratio of PDCCH EPRE to NZP CSI-RS EPRE being 0 dB for link recovery procedures.
In Release 16, key enhancements for CSI-RSRP involved corrections and clarifications for aperiodic CSI-RS triggering, specifically supporting beam switching timing values of 224 and 336. The release also introduced corrections for the default Transmission Configuration Indicator (TCI) state of aperiodic CSI-RS in multi-TRP scenarios and for TCI state codepoint mapping in DCI format 1_2. Furthermore, it provided clarifications on resource and port occupation for duplicate CSI-RS resources and on cross-carrier scheduling with cross-carrier CSI-RS triggering.
- Aperiodic CSI-RS Triggering for UE reporting beamSwitchTiming values of 224 and 336 TS 38.214CR0060
- Correction on aperiodic CSI-RS triggering with beam switching timing of 224 and 336 and on CSI reporting TS 38.214CR0107
- Correction on aperiodic CSI-RS triggering with beam switching timing of 224 and 336 TS 38.214CR0121
- Corrections for default TCI state of AP CSI-RS in multi-TRP TS 38.214CR0131
- Correction on increased number of CSI-RS for mobility per MO TS 38.214CR0133
- Correction on TCI state codepoint mapping for DCI format 1_2 TS 38.214CR0136
+ 12 more changes
In Release 17, specific corrections were introduced for CSI-RSRP-related procedures in multi-TRP (mTRP) and carrier aggregation scenarios. These included a correction on CSI-RS port restriction for mTRP CSI and a correction on the slot offsets of CSI-RS resource pairs for MTRP. Additionally, a Change Request addressed CSI-RS power settings for inter-cell mTRP operations.
- Introduction of NR UE Power Saving Enhancements TS 38.214CR0236
- Introduction of NR small data transmissions in INACTIVE state TS 38.214CR0237
- Corrections on NR UE Power Saving Enhancements TS 38.214CR0258
- Simultaneous transmission of SRS and other channels for intra-band non-contiguous carrier aggregation TS 38.214CR0279
- Correction on UE PDSCH processing procedure time for operation with shared spectrum channel access in FR2-2 in TS 38.214 TS 38.214CR0299
- CR on priority states within the PRS processing window TS 38.214CR0301
+ 19 more changes
In Release 18, the CSI-RSRP function was enhanced through corrections to the CSI processing criteria for new network energy saving (NES) capability signaling and to the threshold for A-CSI-RS reception within the Rel-18 Transmission Configuration Indicator (TCI) framework. These changes refined the procedures for measuring and reporting CSI-RSRP, particularly in relation to advanced power control and unified TCI state management for multi-cell and multi-TRP operations. The updates ensure more reliable and consistent CSI-RSRP measurements under the new energy-saving and multi-transmission point features introduced in the release.
- CR on FDM reception of unicast and multicast PDSCH in RRC_INACTIVE state TS 38.214CR0517
- Corrections on RRC parameters for R18 NES spatial/power domain adaptation TS 38.214CR0544
- Correction of power consistency and phase continuity during cell DRX operation TS 38.214CR0554
- Correction on the highest sub-channel of PSSCH TS 38.214CR0562
- Correction of physical channels and signals during cell DTX/DRX operation TS 38.214CR0566
- Correction on configuration of TCI states for SRS TS 38.214CR0578
+ 17 more changes
In Release 19, enhancements to CSI-RSRP functionality focused on the counting of CSI-RS resources, specifically for scenarios involving simultaneous Non-Zero Power (NZP) CSI-RS resources. The release introduced new counting procedures for NZP-CSI-RS resources referenced by multiple CSI reporting settings and for simultaneous NZP-CSI-RS resource counting in conjunction with NES (Network Energy Saving) operations.
- TEI19 Counting of CSI-RS resource referred by N CSI reporting settings [SimCSI_count] TS 38.214CR0681
- TEI19 Simultaneous NZP-CSI-RS resource counting with NES [SimCSI_countNES] TS 38.214CR0689
- Correction on WUS TCI state TS 38.214CR0731
- Correction on Semi-persistent CSI/Semi-persistent CSI-RS for LTM TS 38.214CR0733
- CR on time restriction for channel measurement of UEIBM in TS 38.214 TS 38.214CR0739
- Correction on association between NZP CSI-RS and CSI-IM TS 38.214CR0744
Explore further
Broader topics and technologies where CSI-RSRP plays a role.
Defining Specifications
3GPP specifications that define or reference CSI-RSRP, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 38.214 vj10 | NR Physical Layer Procedures for Data | Rel-19 |
| TS 38.215 vj10 | NR Physical Layer Measurements | Rel-19 |