Description
The OTA Sensitivity Directions Declaration (OSDD) is a standardized UE capability defined by 3GPP for Over-The-Air (OTA) testing methodologies. It is a critical component in the radiated testing framework, enabling the characterization of a device's total radiated power (TRP) and total isotropic sensitivity (TIS) in a controlled, anechoic chamber environment. The OSDD provides a structured data set from the UE to the test system, detailing the specific spatial directions—typically defined by azimuth and elevation angles—where the device's receiver sensitivity is highest. This information is essential because a UE's antenna system is not perfectly isotropic; its performance varies significantly with direction due to device form factor, internal antenna placement, and user interaction scenarios (like hand grip).
During OTA testing, the device under test (DUT) is placed on a positioning system inside an anechoic chamber. A test probe antenna transmits or receives signals, and the DUT is rotated through various orientations. The OSDD capability allows the test system to intelligently focus its measurement sweeps on the declared sensitivity directions, rather than performing exhaustive, time-consuming spherical scans. The declaration typically includes a list of direction vectors, each associated with a specific operating band and possibly other radio conditions. The test system uses this data to configure the measurement path loss, set the correct beamforming weights if applicable, and determine the precise angular positions for sensitivity measurements.
Architecturally, OSDD is part of the UE Radio Transmission and Reception specifications (e.g., 36.101/38.101 series) and the associated conformance test specifications (e.g., 36.521/38.521). It is reported by the UE during capability exchange procedures, often as part of the RF-Parameters. The underlying mechanism involves the UE's baseband and RF systems internally characterizing its antenna performance, possibly based on factory calibration or real-time estimation. The role of OSDD extends beyond mere testing efficiency; it ensures reproducibility and accuracy of radiated performance metrics, which are vital for regulatory compliance (e.g., FCC, CE marking) and for guaranteeing real-world user experience, as a device's coverage and data throughput are directly tied to its OTA characteristics.
Purpose & Motivation
OSDD was introduced to address the growing complexity and criticality of accurately measuring the radiated performance of modern User Equipment (UE), particularly with the advent of MIMO, carrier aggregation, and later, mmWave beamforming in 5G NR. Traditional conductive testing, where cables are attached directly to antenna ports, became insufficient as it ignored the effects of the device's enclosure, integrated antennas, and user proximity—all of which drastically alter real-world RF performance. OTA testing emerged as the solution, but early methods were slow and inefficient, requiring full spherical scans to find the 'worst-case' or most sensitive directions.
The primary problem OSDD solves is the optimization of OTA test time and resource consumption. Without a priori knowledge of the UE's antenna pattern, test systems had to perform exhaustive searches, significantly increasing the cost and duration of compliance testing. By having the UE declare its most sensitive directions, the test system can perform targeted, high-accuracy measurements precisely where they matter most. This is especially important for mass production testing, where throughput is paramount. Furthermore, OSDD standardizes this declaration, ensuring interoperability between UEs from different manufacturers and test equipment from various vendors, leading to consistent and comparable test results across the industry.
Historically, the need for OSDD became pronounced with LTE-Advanced (Rel-10/11) and the proliferation of multi-antenna systems. Its formal introduction in Rel-12 provided a structured framework that has been extended through subsequent releases to support new features like License-Assisted Access (LAA), enhanced MIMO configurations, and the beam management procedures of 5G NR. It addresses the limitation of 'black-box' testing by enabling a cooperative model where the UE provides essential internal RF characterization data to the external test system.
Classification
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (1 CRs across 1 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the OTA Sensitivity Directions Declaration (OSDD) function was introduced as a new framework for declaring directional receiver performance for NR base stations. Specifically, it defines a set of manufacturer declarations for minimum Equivalent Isotropic Sensitivity (EIS) values and the specific directions, called the sensitivity RoAoA (Range of Angle of Arrival), over which these sensitivity levels apply. This establishes a conformance testing basis for the directional OTA sensitivity requirement for Single Antenna Node (SAN) type 1-O receivers.
- 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
Explore further
Broader topics and technologies where OSDD plays a role.
Defining Specifications
3GPP specifications that define or reference OSDD, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| 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 37.842 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 38.104 vj20 | NR Base Station RF Requirements | Rel-19 |
| TS 38.108 vj20 | NTN NR Satellite Access Node 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 38.181 vj10 | NR Satellite Access Node RF Testing | Rel-19 |
| TS 38.817 | 3GPP TR 38.817 | Rel-12 |
