EISREFSENS

OTA Reference Sensitivity

Physical Layer →
Introduced in Rel-15

EISREFSENS is the minimum received power level at a 5G base station's antenna port required to achieve a defined throughput, ensuring reliable uplink signal detection from user equipment.

Category
Physical Layer
Introduced
Rel-15
Where
Radio Access Network › NG-RAN (5G)
Specifications
7 specs
EISREFSENS Description Purpose Detected Changes Specifications

Description

EISREFSENS, or OTA Reference Sensitivity, is a key performance indicator defined in 3GPP specifications for evaluating the sensitivity of 5G New Radio (NR) base station (gNB) receivers in an Over-the-Air test environment. It is a specific application of the broader Equivalent Isotropic Sensitivity (EIS) concept, tailored for base station equipment. The metric quantifies the minimum power level, expressed in dBm, that must be incident on the gNB's antenna array to achieve a specified reference throughput (typically 95% of the maximum throughput) for a defined reference measurement channel. This measurement inherently includes the effects of the base station antenna's radiation pattern, gain, and any beamforming characteristics under test conditions.

The measurement procedure, detailed in specs like 38.141, involves placing the gNB under test in an anechoic chamber. A test UE or a calibrated radio source transmits a standardized uplink signal. The power received by the gNB antenna is precisely controlled and measured. The test system then evaluates the block error rate (BLER) or throughput of the received signal. By iteratively adjusting the transmit power, the minimum power level required to meet the throughput target is identified. This value is the EISREFSENS. The test is performed for specific NR operating bands, bandwidths, and numerologies (subcarrier spacings), and often for different beam directions if the gNB employs beamforming.

EISREFSENS is critical for validating that a base station can effectively receive signals from User Equipment, especially those at the cell edge where received power is low. It directly impacts the uplink coverage radius of a cell. A lower (better) EISREFSENS value means the gNB can detect weaker signals, enabling wider coverage or better performance in interference-limited scenarios. Standardizing this OTA measurement ensures that base station receivers from different vendors meet minimum performance benchmarks, contributing to consistent network quality and enabling accurate radio network planning. It complements conducted sensitivity tests by providing a system-level validation that includes the antenna subsystem.

Purpose & Motivation

EISREFSENS was introduced in 3GPP Release 15 alongside the first 5G NR specifications to address the unique challenges of base station receiver testing in the 5G era. Previous generations relied more heavily on conducted tests at antenna ports, which became less representative for active antenna systems (AAS) and massive MIMO arrays where the antenna and radio are deeply integrated. Conducted tests could not capture the performance impact of beamforming, antenna coupling, or the overall radiation pattern.

The purpose of defining EISREFSENS was to establish a standardized, realistic method for verifying base station receiver sensitivity in an operational context. It solves the problem of ensuring that the complete receive chain—from the radiating elements through the RF and digital beamforming units—functions correctly. This is especially important for 5G networks that use higher frequencies (like mmWave) with greater path loss and rely on beamforming to maintain link budget. By mandating OTA reference sensitivity tests, 3GPP ensures that base stations deployed in the field will reliably receive uplink transmissions, which is fundamental for network coverage, capacity, and user experience. It provides network operators with a guaranteed performance metric for procurement and deployment.

Detected Changes Across Releases

from 3GPP Change Requests

Specific changes extracted from the „Change history“ tables of 3GPP specifications (16 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.

Rel-15 2 changes

In Release 15, the definition of the OTA reference sensitivity (EISREFSENS) was formally corrected and clarified within TS 38.104, as indicated by the specific Change Request for its definition. This introduced precise terminology, distinguishing EIS (Equivalent Isotropic Sensitivity) and defining the "reference RoAoA" and "sensitivity RoAoA" as key concepts for conformance testing of beamforming base stations. Furthermore, the release established the maximum OTA Test System uncertainty for measuring the OTA reference sensitivity level as ±1.3 dB for specified frequency ranges.

  • CR to TS 38.104 on Combined updates from RAN4 #90 This document combines the proposed changes in the following Draft CRs from RAN4 #90: - R4-1900284, "Draft CR on NR PUCCH format2 performance requirements for TS 38.104" - R4-1900763, "Draft CR to TS 38.104: Update of performance requirement numbers for DFT-s-OFDM based PUSCH" - R4-1900876, "Draft CR to TS 38.104: On RX spurious emissions requirement" - R4-1900968, "Draft CR for 38.104: Performance requirements for NR PUCCH format 1" - R4-1901329, "Draft CR to 38.104: Annex C.6 correction" - R4-1901330, "Draft CR to 38.104: Abbreviations addition" - R4-1901387, "Draft CR to TS 38.104 BS demodulation PUCCH format 0 requirements" - R4-1901474, "Draft CR to TS 38.104: Corrections on transmitter co-existence and co-location requirements" - R4-1901483, "Draft CR to TS 38.104: Corrections on general intermodulation requirement" - R4-1902239, "Draft CR to TS 38.104: Addition of missing EIRP/EIS definitions in terminology in clause 3.1" - R4-1902241, "Draft CR to 38.104; clarification of BS power limits" - R4-1902245, "Draft CR to 38.104: Correction to FR2 OTA Interfering signal mean power units" - R4-1902246, "Draft CR to 38.104; Correction to definition of OTA reference sensitivity" - R4-1902260, "draft CR to TS 38.104 - update emissions scaling" - R4-1902338, "Draft CR: Update on FR1 range extension for TS38.104" - R4-1902389, "draftCR for 38.104 on PUSCH requirements with CP-OFDM and FR1" - R4-1902394, "Draft CR to TS 38.104 – PUSCH requirements with CP-OFDM for FR2" - R4-1902396, "CR: Updates to PUCCH formats 3 and 4 performance requirements in TS 38.104" - R4-1902444, "Draft CR to TS 38.104: Editorial CR for BS demodulation requirements" - R4-1902561, "Draft CR for updating PRACH performance requirements in TS38.104" - R4-1902571, "Corrections to 38.104 Delay profile calculation" - R4-1902642, "Draft CR to TS 38.104: Correction on multi-band operation related requirements" TS 38.104CR0019
  • CR to TS 38.104 Combined updates from RAN4 #90bis and RAN4#91 From RAN4 #90bis: - R4-1903105, "Draft CR to TS 38.104: Corrections on terminologies and editorial errors" - R4-1903319, "Draft CR to TS 38.104: removal of unused definition: "minimum EIRP level under extreme condition"" - R4-1903320, "Draft CR to TS 38.104: OSDD information correction" - R4-1903457, "Draft CR to TS 38.104: Removal of FFS for FR2 TDD OFF power level requirement in clause 9.5" - R4-1903499, "Draft CR to 38.104: Correction to unwanted emissions mask for bands n7 and n38" - R4-1903836, "Draft CR to TS 38.104: Correction on description on multi-band operation in section 4.8" - R4-1904024, "Draft CR to TS 38.104 Applicability rules for BS demodulation" - R4-1904234, "draftCR: Correlation matrix for 8Rx in TS 38.104" - R4-1904723, "Draft CR to TS 38.104: Update of performance requirements for DFT-s-OFDM based PUSCH" - R4-1904726, "draftCR for 38.104 on PUSCH requirements with CP-OFDM and FR1" - R4-1904729, "Draft CR on PRACH performance requirements in TS38.104" - R4-1904734, "Draft CR on TS 38.104 Performance requirement for PUCCH format 1" - R4-1904735, "Draft CR on NR PUCCH format2 performance requirements for TS 38.104" - R4-1904739, "Draft CR to TS 38.104 BS demodulation PUCCH format 0 requirements" - R4-1904745, "draftCR: Updates to PUCCH formats 3 and 4 performance requirements in TS 38.104" - R4-1904799, "Draft CR to TS 38.104: FRC update for PUSCH FR1 mapping type B and FR2 DMRS 1+1" - R4-1904816, "Draft CR : Clarification on step 5 and step 6 for delay profiles calculation (38.104)" - R4-1904842, "Draft CR to TS 38.104 BS demodulation CP-OFDM PUSCH FR2 requirements" - R4-1905126, "draft CR to 38.104 for TAE requirements" - R4-1905139, "draft CR to TS 38.104 on EVM measurement (Annex B and C)" - R4-1905140, "Draft CR: editorial correction on FR1 spurious emission requirement in TS38.104" - R4-1905143, "Draft CR for TS 38.104: Addition of NOTE for transmitter intermodulation requirements in certain regions" - R4-1905144, "Draft CR to TS 38.104: FRC reference corrections for the Rx requirements" - R4-1905145, "Draft CR to TS 38.104: Clarification on application of interfering signal offsets for ACS, blocking and intermodulation requirements" - R4-1905148, "Draft CR to TS 38.104: Corrections on out-of-band blocking requirement" From RAN4 #91: - R4-1906002, "Draft CR to 38.104: Subclause 6.7 and 9.8 transmitter intermodulation – correction of interfering signal type" - R4-1906096, "Draft CR to 38.104: Correction of frequency range for OTA spurious emissions" - R4-1906311, "Draft CR to 38.104: Correction on FRC (Annex A)" - R4-1906346, "Removal of n65 in Rel-15 38.104" - R4-1906915, "Draft CR to TS 38.104: Clarification on application of interfering signal offsets for OTA ACS, blocking and intermodulation requirements" - R4-1906918, "Draft CR to TS 38.104: Clarification on type of interfering signal for ACS, in-band blocking and ICS requirements" - R4-1907110, "Draft CR to TS 38.104: correction of the fundamental frequency limit of 2.55GHz for the spurious emissions" - R4-1907246, "Draft CR to TS 38.104: Update of performance requirements for DFT-s-OFDM based PUSCH" - R4-1907249, "Draft CR to TS 38.104: Correction on the terminology in PUSCH FRC tables" - R4-1907252, "Draft CR to TS38.104: Updates of PRACH performance requirements" - R4-1907255, "Draft CR on NR PUCCH format2 performance requirements for TS 38.104" - R4-1907258, "Draft CR on NR UCI on PUSCH performance requirements for TS 38.104" - R4-1907261, "draftCR: Updates to PUCCH formats 3 and 4 performance requirements in TS 38.104" - R4-1907266, "Draft CR on TS 38.104 Performance requirement for PUCCH format 1" - R4-1907267, "Draft CR on TS 38.104 Performance requirement for multi-slot PUCCH format 1" - R4-1907272, "Draft CR to TS 38.104 BS demodulation PUCCH format 0 requirements" - R4-1907275, "Draft CR to TS 38.104 BS demodulation CP-OFDM PUSCH FR2 requirements" - R4-1907277, "draftCR for 38.104 on PUSCH requirements with CP-OFDM and FR1" - R4-1907629, "Draft CR to 38.104: Term “reference signal” replacing by term “ideal signal” in EVM context" - R4-1907634, "Draft CR to 38.104: corrections to the EVM annex" - R4-1907659, "Draft CR to TS 38.104 on Spurious emission Category B in FR2" - R4-1907661, "Draft CR to 38.104 Definition of contiguous transmission bandwidth" - R4-1907662, "Draft CR to 38.104: BS TAE requirements" - R4-1907664, "Draft CR to 38.104: Clarification of interferer RB frequency for narrowband blocking" - R4-1907672, "Draft CR for TS 38.104: Correction on EVM" - R4-1907689, "Correction to CA carrier spacing" TS 38.104CR0029
Rel-16 2 changes

In Release 16, the EISREFSENS (OTA Reference Sensitivity) function saw clarifications and corrections to its testing framework, including specific updates for base stations supporting polarization. The release also formally defined the associated OTA Test System uncertainty for these measurements as ±1.3 dB for E-UTRA in frequencies below 3 GHz, integrating these requirements for both traditional and NTN (Non-Terrestrial Network) operations.

  • CR to T 38.104: Implementation of endorsed draft CRs from RAN4#92 (Rel-16) (Mirrors changes in R4-1908440 for Rel-15 TS 38.104) - R4-1907940, "Draft CR to TS 38.104: Correction on the terminology in FRC tables in A.1 and A.2" - R4-1908307, "Draft CR to TS 38.104: Clarification on application of OTA receiver requirements for BS supporting polarization" - R4-1908387, "Draft CR for TS38.104: editorial correction for reference meausrement channel" - R4-1908619, "Draft CR to TS38.104: Correction on interferer frequency offset values for ACS" - R4-1908629, "Draft CR to TS38.104: Corrections on EVM window length (Annex B.5.2, C.5.2)" - R4-1908774, "DraftCR to 38.104: Editorial Corrections to redudant units in clause 10.8.3" - R4-1908805, "Draft CR to 38.104: Limits in FCC title 47 for OTA operating band unwanted emissions (9.7)" - R4-1909270, "Draft CR to TS 38.104: Receiver spurious emissions frequency correction" - R4-1909309, "DraftCR to TS 38.104: text corrections, Rel-15" - R4-1909310, "DraftCR to 38.104: correction of TAB connectors mapping to TAB connector TX min cell group, Rel-15" - R4-1909416, "draft CR 38.104 - correct reference to annex F" - R4-1910066, "Draft CR to TS 38.104: Update of performance requirements for DFT-s-OFDM based PUSCH" - R4-1910069, "Draft CR on NR PUCCH format2 performance requirements for TS 38.104" - R4-1910072, "Draft CR on NR UCI on PUSCH performance requirements for TS 38.104" - R4-1910075, "draftCR for 38.104 on PUSCH requirements with CP-OFDM and FR1" - R4-1910078, "Draft CR to TS38.104: Updates to NR PRACH performance requirements" - R4-1910081, "Draft CR to TS 38.104 BS demodulation PUCCH format 0 requirements" - R4-1910084, "Draft CR to TS 38.104 BS demodulation CP-OFDM PUSCH FR2 requirements" - R4-1910088, "Draft CR for 38.104: Performance requirements for NR PUCCH format 1" - R4-1910089, "Draft CR for 38.104: Performance requirements for NR multi-slot PUCCH" - R4-1910094, "draftCR: Updates to PUCCH formats 3 and 4 performance requirements in TS 38.104" - R4-1910431, "Corrections to EVM calculations in 38.141-1 annex B" - R4-1910462, "Draft CR to 38.104: Correction on regional requirements (4.5)" - R4-1910493, "Draft CR to TS 38.104 correction to Annex C.7" - R4-1910606, "Draft CR for TS 38.104: Channel spacing for adjacent NR carriers" TS 38.104CR0034
  • CR to TR 38.104: Correction of table reference of interfering signal for ACS requirement TS 38.104CR0085
Rel-17 2 changes

In Release 17, the enhancements for the OTA Reference Sensitivity (EISREFSENS) function included a clarified reference to Fixed Reference Channels (FRCs) for testing and a correction to the Integrated Access and Backhaul Mobile Termination (IAB-MT) timing reference point. The specification also formally defined key terms and procedures for OTA sensitivity, such as the **sensitivity RoAoA** and the **receiver target reference direction**, and established specific maximum OTA test system uncertainties for OTA reference sensitivity level measurements.

  • CR to TS 38.104 on reference to FRCs TS 38.104CR0411
  • Correction to IAB-MT timing reference point in TS 38.174 TS 38.174CR0042
Rel-18 7 changes

In Release 18, updates to the EISREFSENS (OTA Reference Sensitivity) function primarily involved reference corrections and clarifications in supporting specification tables. This included corrections to the reference of PREFSENS for in-band and out-of-band blocking specific to band n104, ensuring accurate procedural linkage. Furthermore, technical maintenance extended to refining table references for OTA operating band unwanted emission limits and for the extension of NR operation to 71 GHz.

  • CR to TS 38.104 on table references for OTA operating band unwanted emission limits TS 38.104CR0437
  • CR to TS 38.104: NR-ARFCN table reference correction for band n263, Rel-18 TS 38.104CR0460
  • CR to TS 38.104 on corrections of table references for extending current NR operation to 71GHz TS 38.104CR0468
  • CR for TR 38.104, Correction on reference of PREFSENS for in-band blocking and out-of-band blocking for band n104 TS 38.104CR0472
  • (NR_SUL_UL_n24-Core) Missing reference to FCC Order DA 20-48 TS 38.104CR0659
  • (NR_IAB-Perf) Reference Table Correction in 38.174 TS 38.174CR0104

+ 1 more changes

Rel-19 3 changes

In Release 19, the EISREFSENS function was updated to correct the reference sensitivity level requirements for base stations supporting NB-IoT operation in NR in-band specifically for a 3 MHz channel bandwidth. The release also included corrections to the annex references in the conformance test cases TC 8.2.6 and TC 8.2.14 for OTA testing. These changes ensure alignment with the specified measurement testing system uncertainty, which is defined as identical for NB-IoT standalone mode and NB-IoT operation in NTN NR in-band.

  • (NR_FR1_lessthan_5MHz_BW-Core)CR for TS38.104, Correction on reference sensitivity levels requirement apply to BS that supports NB-IoT operation in NR in-band for 3 MHz channel bandwidth TS 38.104CR0739
  • Correct Annex references in TC 8.2.6 TS 38.141CR0695
  • Correct Annex references in TC 8.2.14 TS 38.141CR0697

Explore further

Broader topics and technologies where EISREFSENS plays a role.

Topics
SON (Self-Organizing Networks)Testing & ConformanceMIMO & Beamforming5G NR (New Radio)Lawful InterceptRadio Access Network
Technologies
5G

Defining Specifications

3GPP specifications that define or reference EISREFSENS, with the latest known release. Sourced from the 3GPP document catalog — see methodology.

SpecificationTitleRelease
TS 36.181 vj30 E-UTRA RF Test Methods for Satellite Access Node Rel-19
TR 37.941 vj20 RF Conformance Testing Background for Radiated BS Requirements Rel-19
TS 38.104 vj20 NR Base Station RF Requirements Rel-19
TS 38.141 vj20 NR Base Station RF Conformance Testing Part 1 Rel-19
TS 38.174 vj10 NR Integrated Access and Backhaul Radio Spec Rel-19
TS 38.176 vj20 IAB Conformance Testing Specification Rel-19
TS 38.817 3GPP TR 38.817 Rel-15