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5G NR QCL Types: Type-A, Type-B, Type-C, Type-D

5g nr qcl quasi co-location channel parameter

This page describes the different types of Quasi Co-Location (QCL) in 5G New Radio (NR). The common 5G NR QCL types include Type-A, Type-B, Type-C, and Type-D. QCL stands for Quasi Co-Location.

Introduction to QCL

The quasi co-location relationship is configured by the higher layer parameter qcl-Type1 for the first Downlink Reference Signal (DL RS) and qcl-Type2 for the second DL RS (if configured).

For scenarios involving two DL RSs, the QCL types must not be the same, regardless of whether the references are to the same DL RS or different DL RSs. This ensures diversity in the information provided.

The quasi co-location types corresponding to each downlink (DL) RS is determined by the higher layer parameter qcl-Type in QCL-Info, and it can take one of the following values.

5G NR QCL Types

The following table summarizes the different 5G NR QCL types and their descriptions:

QCL typeDescription
Type-A{ Doppler shift, Doppler spread, average delay, delay spread }
Type-B{ Doppler shift, Doppler spread }
Type-C{ Doppler shift, average delay }
Type-D{ Spatial Rx parameter }

In essence, QCL types allow the receiver to assume certain channel characteristics are similar between different reference signals. This simplifies signal processing and improves performance. Different QCL types signal different sets of shared parameters.

References

  • 3GPP TS 38.214 V15.2.0 (2018-06)