5G NR CSI-RS & CSI Reporting Visualizer
Configure, inspect, and validate CSI-RS resources, CSI-IM resources, and CSI reporting occasions—then visualize their impact on downlink RE occupancy and PDSCH capacity.
Time-Frequency Resource Element (RE) Inspector
Select a CSI-RS resource to inspect its subcarrier (0..11) x symbol (0..13) mapping pattern per Physical Resource Block (PRB).
PRB #0 Resource Grid
RE Coordinate Details
Click any occupied RE in the grid
Inspect port indices, CDM group IDs, and exact subcarrier locations.
5G NR CSI-RS & CSI Reporting Architecture (Rel-17 Baseline)
In 5G NR (3GPP TS 38.211 & TS 38.214), Channel State Information Reference Signals (CSI-RS) enable the gNB to measure downlink channel conditions, beam quality, and interference. Unlike 4G LTE Cell-Specific Reference Signals (CRS) which are transmitted continuously across the entire bandwidth, 5G CSI-RS is highly configurable and beamformed.
NZP CSI-RS
Non-Zero Power CSI-RS is transmitted by gNB antenna ports to allow the UE to calculate Channel Quality Indicator (CQI), Precoding Matrix Indicator (PMI), and Rank Indicator (RI).
ZP CSI-RS
Zero-Power CSI-RS reserves REs (mutes PDSCH data transmission) to prevent interference with neighboring cell CSI-RS or to match CSI-IM patterns.
CSI-IM
CSI Interference Measurement resources allow the UE to measure interference from surrounding cells or multi-user MIMO co-channel transmissions.
Frequently Asked Questions
What is the difference between CSI-RS transmission and CSI reporting?
CSI-RS transmission is a downlink reference signal sent from the gNB to the UE. CSI reporting is an uplink transmission (on PUCCH or PUSCH) sent from the UE back to the gNB containing measured channel feedback (CRI, RI, PMI, CQI, or RSRP).
How does density affect CSI-RS RE occupancy?
Density defines how many REs per PRB are occupied by a CSI-RS port. Density 1 means 1 RE per PRB per port. Density 3 means 3 REs per PRB. Density 0.5 (even/odd PRB) occupies REs in every second PRB, halving overhead.
Why does PDSCH data RE capacity reduce when CSI-RS is enabled?
PDSCH rate matches around REs occupied by NZP CSI-RS, ZP CSI-RS, and CSI-IM. Each occupied RE reduces the number of available data subcarriers for PDSCH payload transmission.