Description
Equivalent Isotropic Sensitivity (EIS) is a fundamental performance parameter defined in 3GPP specifications for evaluating the sensitivity of a receiver in an Over-the-Air (OTA) test environment. Unlike conducted sensitivity measurements, which are made at a physical connector, EIS quantifies the sensitivity at the antenna reference point, incorporating the effects of the antenna's radiation pattern, gain, and efficiency. The metric is expressed in dBm and is derived by measuring the total radiated power (TRP) required to achieve a specific reference throughput, such as 95% of the maximum throughput for a given reference measurement channel. This approach provides a more realistic assessment of receiver performance as experienced by an end-user in real-world conditions, where the antenna is an integral part of the device.
The measurement methodology for EIS is detailed across multiple 3GPP test specifications (e.g., 38.521 for NR). It typically involves placing the device under test (DUT) in an anechoic chamber and illuminating it with a known, controlled radio signal from a base station emulator. The test system measures the power received by the DUT's antenna and the resulting throughput. By systematically varying the input power and mapping the throughput performance, the minimum power level required to meet the throughput target is determined. This value is then normalized to represent the sensitivity as if the device had an ideal isotropic antenna, hence the term 'equivalent isotropic'.
EIS is crucial for characterizing both User Equipment (UE) and base station (gNB) receivers. For UEs, it ensures that devices can reliably decode signals in weak coverage areas, directly impacting call quality and data rates. For base stations, EIS measurements validate the receiver's ability to detect uplink transmissions from distant UEs, which is essential for cell edge coverage. The parameter is tested across multiple frequency bands, bandwidths, and modulation schemes to ensure consistent performance. By standardizing this OTA measurement, 3GPP enables fair and comparable assessments of receiver sensitivity across different manufacturers and device form factors, eliminating ambiguities that could arise from conducted tests alone.
Purpose & Motivation
EIS was introduced to address the limitations of traditional conducted sensitivity testing, which isolates the radio frequency (RF) front-end from the antenna. As mobile devices evolved with integrated, non-removable antennas, it became impossible to measure sensitivity directly at a connector. Conducted tests also failed to account for antenna performance degradation due to design, housing, or user interaction (e.g., hand grip). This gap meant that a device with excellent conducted sensitivity could still perform poorly in real-world use if its antenna was inefficient.
The creation of EIS as a standardized OTA metric in 3GPP Release 12 provided a holistic evaluation method that reflects true receiver performance. It solves the problem of ensuring that the entire receive chain—from antenna through RF components to baseband processing—meets minimum sensitivity requirements. This is particularly important for guaranteeing consistent user experience in challenging radio conditions, such as at cell edges or inside buildings. By defining EIS, 3GPP enabled regulators and operators to enforce performance standards that correlate directly with network coverage and quality of service, driving improvements in device design and antenna technology.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (11 CRs across 3 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-12, normative work from Rel-15.
In Release 15, the standardization of the Equivalent Isotropic Sensitivity (EIS) function was enhanced by introducing formal definitions and clarifications for Over-the-Air (OTA) reference sensitivity measurements, including polarization wording improvements. The release also added support for new test methodologies, such as the 2D Compact Range procedure for measuring EIS, alongside the existing anechoic and reverberation chamber approaches. These updates provided a more complete framework for measuring Total Radiated Sensitivity (TRS) in an isotropic Rayleigh fading environment.
- CR to TS 37.105 - polarisation wording improvements for OTA s reference sensitivity TS 37.105CR0118
- Correction to definition of OTA reference sensitivity TS 37.105CR0123
- CR to TS 37.145-2 - polarisation wording improvements for OTA reference sensitivity TS 37.145CR0068
- Correction to definition of OTA reference sensitivity TS 37.145CR0073
- CR to TR 37.843: Addition of 2D Compact Range. MU, calibration and test procedure for EIRP and EIS. TS 37.843CR0029
- 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
+ 1 more changes
In Release 16, a key update for the Equivalent Isotropic Sensitivity (EIS) function was the correction of testing procedures for equivalent beams. The release specifically refined the measurement process for Total Radiated Sensitivity (TRS), detailing how EIS is measured from specific directions using selected sampling grids and orthogonal polarizations to ultimately calculate the TRS.
- CR to 37.145-2: correction of equivalent beams testing, Rel-16 TS 37.145CR0176
In Release 19, the EIS (Equivalent Isotropic Sensitivity) function saw updates focused on clarifying reference sensitivity requirements for specific network equipment and scenarios. The changes included corrections for base stations and Satellite Access Nodes (SAN) supporting NB-IoT operation in 3 MHz NR in-band and NTN in-band deployments, respectively. Furthermore, a new SAN type 1-H was introduced for Over-The-Air (OTA) sensitivity requirements, expanding the defined equipment for NTN operations.
- (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
- (TEI18)CR for TS38.108, Correction on reference sensitivity levels requirement apply to SAN that supports NB-IoT operation in NTN NR in-band[NTNNBIoT_inbandNTNNR] TS 38.108CR0120
- (NR_NTN_solutions-Core)CR for TS38.108, Add SAN type 1-H for OTA sensitivity requirement TS 38.108CR0123
Explore further
Broader topics and technologies where EIS plays a role.
Defining Specifications
3GPP specifications that define or reference EIS, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 34.114 vc20 | Radiated Performance Test Procedure for UE/MS | Rel-12 |
| TS 36.108 vj10 | Satellite Access Node RF Requirements | Rel-19 |
| TS 36.181 vj30 | E-UTRA RF Test Methods for Satellite Access Node | Rel-19 |
| TS 37.105 vj10 | AAS Base Station Transmission & Reception Requirements | Rel-19 |
| TS 37.145 vj10 | AAS Base Station Conducted Conformance Testing | Rel-19 |
| TS 37.544 vg70 | UE Radiated Performance Test Procedures | Rel-16 |
| TS 37.842 vd30 | BS RF Requirements for Active Antenna Systems | Rel-13 |
| TR 37.843 vf70 | AAS BS Radiated RF Requirement Background | Rel-15 |
| TR 37.941 vj20 | RF Conformance Testing Background for Radiated BS Requirements | Rel-19 |
| TS 38.101 vj31 | NR User Equipment Radio Transmissions | Rel-19 |
| TS 38.104 vj20 | NR Base Station RF Requirements | Rel-19 |
| TS 38.108 vj20 | NTN NR Satellite Access Node RF Requirements | Rel-19 |
| TS 38.115 vj20 | NR Repeater RF Conformance Testing Part 1 | Rel-19 |
| TS 38.141 vj20 | NR Base Station RF Conformance Testing Part 1 | Rel-19 |
| TS 38.161 vj10 | NR UE TRP and TRS Requirements for FR1 | 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 38.181 vj10 | NR Satellite Access Node RF Testing | Rel-19 |
| TS 38.521 vj20 | NR Physical Layer UE Conformance Testing | Rel-19 |
| TR 38.810 vg70 | NR OTA Test Methods Study | Rel-16 |
| TS 38.817 | 3GPP TR 38.817 | Rel-12 |
| TS 38.831 vg10 | UE RF Requirements for FR2 Enhancements | Rel-16 |
| TS 38.870 vj20 | Enhanced OTA Test Methods for NR FR1 TRP/TRS | Rel-19 |
| TR 38.871 vi20 | Technical Report | Rel-18 |
| TR 38.877 vi10 | Technical Report | Rel-18 |
| TR 38.884 vi20 | Technical Report | Rel-18 |
| TR 38.903 vj00 | Test Tolerances & Measurement Uncertainties | Rel-19 |