Description
The Physical Device-to-Reader Channel (PDRCH) is a new air interface component defined in 3GPP Release 19, primarily within the context of NR-Light (RedCap) and enhanced IoT work items. It establishes a unidirectional or bidirectional physical layer channel enabling efficient communication between an active 'Reader' device (which could be a base station, a dedicated reader, or a capable UE) and a potentially large number of simple, low-cost 'Device' nodes. These devices are typically passive (backscatter-based) or semi-passive (battery-assisted) tags or sensors, such as those used in RFID, smart logistics, or industrial monitoring. The PDRCH is designed to be extremely resource-efficient, minimizing the energy and complexity required at the Device side.
The PDRCH operates within the NR (New Radio) framework and can be configured in licensed spectrum (as part of an operator's network) or in unlicensed/shared spectrum (for private deployments). From a physical layer perspective, the PDRCH defines specific waveforms, modulation schemes (often very simple like OOK or BPSK), and resource allocation methods (time/frequency blocks) that are optimized for short, bursty transmissions and high-sensitivity reception. The Reader transmits a powerful, continuous wave (CW) or a modulated excitation signal that provides both power (for passive devices via RF energy harvesting) and a clock reference. Devices respond by modulating their data onto this carrier using backscatter techniques or by transmitting a simple uplink signal, all within the pre-defined PDRCH resources.
Key architectural components include the PDRCH configuration, which is broadcast by the network or the Reader, informing Devices of the timing, frequency, and access parameters. The channel supports multiple access schemes, potentially using techniques like time-slotted ALOHA or FDMA to handle collisions when many Devices attempt to respond. The protocol stack above the PDRCH is lightweight, possibly bypassing higher-layer protocols for very small data packets to reduce overhead. The PDRCH enables two primary operations: Inventory, where the Reader discovers and identifies all Devices in its coverage area, and Data Transfer, where the Reader reads data from or writes data to specific Devices. This channel is managed by the network's RAN and can be integrated with core network functions for device management and data aggregation.
Purpose & Motivation
The PDRCH was created to address the limitations of existing cellular IoT technologies (like NB-IoT and LTE-M) and non-cellular RFID systems for next-generation massive-scale sensing and identification. While NB-IoT excels at connecting battery-powered sensors, it is still too complex and energy-intensive for truly passive, cost-sensitive devices like item-level RFID tags. Conversely, traditional RFID systems (e.g., UHF Gen2) operate in unlicensed bands with limited range, reliability, and lack of integration with wide-area cellular networks for seamless data backhaul and management.
PDRCH aims to bridge this gap by defining a standardized, cellular-assisted channel that combines the best of both worlds: the ultra-low cost and zero-power operation of passive RFID with the managed, reliable, and wide-coverage attributes of a licensed cellular network. This solves the problem of connecting billions of 'things'—from products in a warehouse to sensors in a farm—that are currently offline or rely on proprietary, isolated systems. By operating under the 3GPP umbrella, PDRCH enables global scale, interoperability, and direct integration with operator networks for authentication, security, and data services.
Furthermore, it supports new business models and use cases for operators, such as providing 'sensing-as-a-service' or enabling high-accuracy asset tracking across wide areas. The use of licensed spectrum portions can improve reliability and reduce interference compared to crowded unlicensed ISM bands. The creation of PDRCH in Release 19 reflects 3GPP's expansion beyond traditional human-centric communication to encompass pervasive machine-to-machine connectivity, forming a critical piece of the roadmap towards the vision of a truly connected physical world.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (14 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the PDRCH (Physical Device-to-Reader Channel) function was introduced with new physical layer updates and clarifications for logical channel restrictions. The release specifically defined the D2R channel bandwidth supporting a single AIoT RF carrier for backscattering from devices, along with detailed transmission bandwidth configurations and channel rasters for operating bands n5, n8, and n28. These specifications established the foundational RF characteristics and resource mappings for Ambient IoT device communications.
In Release 16, the new PDRCH (Physical Device-to-Reader Channel) function introduced specific D2R channel bandwidths and transmission bandwidth configurations for Ambient IoT devices, operating independently of the base station's channel bandwidth. This included defining nominal transmission bandwidths for device channels, such as 3.75 kHz, and establishing the mapping between the channel raster and the corresponding resource elements for uplink transmission.
- Mapping of Uplink Traffic to Backhaul RLC Channels TS 38.300CR0255
In Release 17, the new PDRCH (Physical Device-to-Reader Channel) function introduced specific channel bandwidths and transmission bandwidth configurations for the D2R (Device-to-Reader) link, including a 3.75 kHz device channel bandwidth. This was defined alongside the established R2D (Reader-to-Device) channel structures, with detailed specifications for operating bands, guard bands, and the mapping between the channel raster and resource elements.
- Running CR to 38300 for Multi-USIM devices support TS 38.300CR0422
In Release 18, the PDRCH (Physical Device-to-Reader Channel) function introduced enhancements for In-Device Co-existence (IDC) to improve operational reliability. These updates included refined specifications for the D2R channel bandwidth, transmission bandwidth configurations, and the mapping between the channel raster and resource elements to support a single AIoT RF carrier. The corrections also ensured alignment of the R2D transmission bandwidth configuration with guardband requirements across specified operating bands.
In Release 19, the PDRCH (Physical Device-to-Reader Channel) function saw refinements focused on correcting and clarifying the Ambient IoT physical layer specifications. Key updates included corrections to the A-IoT device symbol definition, device output RF spectrum emissions, and specific device RF testing requirements. These changes provided more precise definitions for the D2R channel bandwidth, transmission bandwidth configurations, and the mapping between the channel raster and resource elements for device operation.
- CR for TS 38.191, Correction on A-IoT Device Symbol TS 38.191CR0001
- CR for TS 38.191, Correction on A-IoT Device Output RF spectrum emissions TS 38.191CR0002
- Corrections for device RF requirements TS 38.191CR0006
- CR on 38.191 for A-IoT device testing TS 38.191CR0003
- Corrections to the Ambient IoT physical layer TS 38.291CR0001
- Corrections to the Ambient IoT physical layer TS 38.291CR0002
In Release 20, the PDRCH (Physical Device-to-Reader Channel) function was enhanced for Ambient IoT in NR outdoor for active devices, as detailed in RAN1 and RAN4 study outcomes. The specification introduced specific D2R (Device-to-Reader) channel bandwidths and transmission bandwidth configurations for active devices, defining parameters like nominal transmission bandwidth and small frequency shift. Furthermore, it established new operating bands (n5, n8, n28) and associated channel arrangements, including supported R2D channel bandwidths and subcarrier spacings, for these active Ambient IoT deployments.
Explore further
Broader topics and technologies where PDRCH plays a role.
Defining Specifications
3GPP specifications that define or reference PDRCH, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 38.191 vj00 | NR Ambient IoT RF Characteristics | Rel-19 |
| TS 38.291 vj20 | Ambient IoT Physical Layer Specification | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.391 vj00 | NR; Ambient IoT MAC Protocol Spec | Rel-19 |
| TS 38.769 vk00 | Ambient IoT Solutions in NR | Rel-20 |