Description
SL-PRS-RSRPP is an advanced physical layer measurement defined in 3GPP specifications 37.571, 38.305, and 38.355. It extends the concept of RSRP by measuring the received power of SL-PRS on a per-path basis, capturing the power contribution from individual multipath components. Unlike SL-PRS-RSRP, which provides an aggregate power measurement, SL-PRS-RSRPP dissects the received signal into distinct paths based on their delay profiles, offering a more detailed view of the channel's impulse response. This is particularly valuable for positioning techniques that leverage multipath information, such as fingerprinting or enhanced Time of Arrival (ToA) estimation.
The measurement process involves the receiving UE performing channel estimation using the known SL-PRS sequences. Advanced algorithms, like correlation-based detection or inverse fast Fourier transform (IFFT) processing, are used to identify and isolate individual propagation paths from the composite received signal. For each detectable path, the UE calculates the received power, typically reporting the strongest paths or those above a certain threshold. The results can include parameters like path power, delay, and possibly angle information, providing a rich dataset for positioning algorithms.
Architecturally, SL-PRS-RSRPP measurement requires sophisticated signal processing capabilities in the UE's physical layer, often involving baseband processing units and dedicated hardware for correlation and Fourier transforms. Key components include the SL-PRS configuration, the channel estimation algorithm, and the path detection criteria. Its role is to enable high-resolution positioning by exploiting multipath diversity. By analyzing the power and delay of multiple paths, positioning algorithms can better distinguish between line-of-sight (LOS) and non-line-of-sight (NLOS) conditions, mitigate multipath errors, and improve location accuracy in urban canyons, indoor environments, and other complex propagation scenarios.
Purpose & Motivation
SL-PRS-RSRPP was introduced in Release 18 to address the limitations of aggregate power measurements in multipath-rich environments, which are common in sidelink scenarios like urban V2X and factory floors. Traditional RSRP measurements could not distinguish between different propagation paths, leading to positioning errors when strong reflected paths masked the true direct path or when multipath was misinterpreted as movement.
Its creation was motivated by the need for sub-meter positioning accuracy in advanced use cases such as autonomous vehicle maneuvering and drone swarming. Previous approaches, relying on single-path power measurements, struggled in NLOS conditions and dense multipath environments. By providing per-path power measurements, SL-PRS-RSRPP enables more sophisticated positioning algorithms that can identify and utilize multiple signal paths, improving robustness against multipath fading, enhancing NLOS detection, and ultimately delivering higher positioning precision and reliability.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (39 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the SL-PRS-RSRPP function was not explicitly introduced or detailed within the provided grounding context. The referenced specifications and change request titles focus on core positioning architecture, signalling between network nodes, and the definition of measurement gaps for various positioning methods, but they do not contain specific technical details or procedures for a Sidelink Positioning Reference Signal based RSRP measurement capability.
- Signalling between an LMF and NG-RAN node/UE TS 38.305CR0001
- Gaps for positioning measurements TS 38.305CR0002
- CR to 38.305 on use of positioning measurement gaps for subframe and slot timing detection towards E-UTRA TS 38.305CR0008
- Minor restructuring of sensor references and addition of sensor methods (IMU) TS 38.305CR0009
- Adding missing reference for autonomous and measuremnts gaps for Inter-RAT RSTD measurements TS 38.305CR0010
- Corrections for Positioning Architecture TS 38.305CR0015
In Release 16, the new SL-PRS-RSRPP function was introduced as part of the broader standardization of NR positioning and the Sidelink Positioning Protocol (SLPP). This function specifically enables the measurement of Reference Signal Received Path Power based on Sidelink Positioning Reference Signals, which supports new sidelink-based positioning methods like SL-RTT (Sidelink Round-Trip Time) for performance testing. The introduction is detailed within the conformance test specifications for these new NR and sidelink positioning capabilities.
- Introduction of B1C signal in BDS system in A-GNSS TS 38.305CR0013
- Introduction of NR positioning TS 38.305CR0017
- Introduction of NR positioning TS 38.305CR0034
- Update B1I signal ICD file to v3.0 in BDS system in A-GNSS TS 38.305CR0024
- Corrections to NR Positioning TS 38.305CR0025
- Correction to SUPL support for NR positioning methods TS 38.305CR0028
+ 6 more changes
In Release 17, the SL-PRS-RSRPP function was introduced as a new capability within the broader sidelink positioning enhancements. This function enables a device to measure the Reference Signal Received Path Power based on Sidelink Positioning Reference Signals transmitted by other devices, supporting new positioning methods like SL-RTT. The associated test scenarios and assistance data for this and other new positioning procedures were defined in the conformance specifications.
- Introduction of R17 Positioning Enhancements TS 38.305CR0086
- 38.305 CR for Positioning WI TS 38.305CR0099
- Stage 2 corrections for NR Positioning Enhancements TS 38.305CR0100
- Corrections to stage 2 descriptions for NR positioning TS 38.305CR0118
- Miscellaneous corrections for Positioning Stage2 TS 38.305CR0119
- Positioning Information Transfer TS 38.305CR0141
+ 3 more changes
In Release 18, the SL-PRS-RSRP function was introduced as part of the expanded and improved NR positioning enhancements. This new capability, defined within the Sidelink Positioning Protocol (SLPP), enables power-based measurements using Sidelink Positioning Reference Signals for relative or absolute positioning between UEs. The release also included specific clarifications and corrections for sidelink positioning procedures, such as defining the maximum number of other UEs involved.
- Introduction of 'Expanded and improved NR positioning TS 38.305CR0150
- Support of NR Positioning Enhancements TS 38.305CR0161
- Positioning restrictions for UE-to-network remote UEs [PosL2RemoteUE] TS 38.305CR0134
- Correction on support of Bluetooth positioning mode [BT-AoA-AoD] TS 38.305CR0157
- Update of stage 2 positioning information TS 38.305CR0173
- Correction on assistance data transfer in SL positioning for stage-2 TS 38.305CR0175
+ 2 more changes
In Release 19, the SL-PRS-RSRPP function was introduced as a new sidelink positioning capability, enabling UEs to measure and report Reference Signal Received Path Power based on dedicated Sidelink Positioning Reference Signals. This addition is documented within the NR Sidelink Positioning Protocol (SLPP) specification, providing a direct method for power-based ranging measurements between devices. The conformance testing framework for positioning was updated accordingly to include scenarios and assistance data for this new sidelink measurement procedure.
- Introduction of AIML Positioning TS 38.305CR0190
- Corrections on AIML Positioning TS 38.305CR0197
- Corrections on LPHAP, carrier phase, bandwidth aggregation and frequency hopping for positioning (R19 Cat. A CR) TS 38.305CR0198
- Correction to Positioning activation and deactivation procedure TS 38.305CR0200
Explore further
Broader topics and technologies where SL-PRS-RSRPP plays a role.
Defining Specifications
3GPP specifications that define or reference SL-PRS-RSRPP, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 37.571 vj00 | UE Conformance for Positioning | Rel-19 |
| TS 38.305 vj00 | NG-RAN UE Positioning Stage 2 | Rel-19 |
| TS 38.355 vj00 | Sidelink Positioning Protocol (SLPP) | Rel-19 |