Description
The Physical Downlink Shared Channel (PDSCH) is a fundamental downlink transport channel in 3GPP radio access technologies, including UMTS, LTE, and NR. It carries all user-plane data (such as internet packets) and most control-plane information (like RRC messages and system information blocks) from the base station (eNodeB in LTE, gNB in NR) to the user equipment (UE). The channel is 'shared' because its time-frequency resources are dynamically allocated among multiple UEs by the base station scheduler in each transmission time interval (TTI), based on factors like channel quality, QoS requirements, and fairness.
In operation, the PDSCH utilizes Orthogonal Frequency Division Multiple Access (OFDMA) in LTE and cyclic prefix OFDM (CP-OFDM) in NR. The scheduler determines which resource blocks (RBs) are assigned to which UE for each subframe (LTE) or slot (NR). The UE must first decode the Physical Downlink Control Channel (PDCCH) to find its Downlink Control Information (DCI), which contains the scheduling assignment specifying the RBs, modulation and coding scheme (MCS), and other parameters for its PDSCH reception. The data on PDSCH is then demodulated and decoded using the indicated parameters.
The PDSCH's performance is critical for overall system capacity and data rates. It supports advanced features like Multiple Input Multiple Output (MIMO) transmission (e.g., spatial multiplexing, beamforming), hybrid automatic repeat request (HARQ) for error correction, and adaptive modulation and coding (AMC) to match the transmission to the radio channel conditions. In NR, the PDSCH design was enhanced with more flexible numerology (subcarrier spacing), mini-slot scheduling for low latency, and support for diverse use cases from enhanced mobile broadband (eMBB) to ultra-reliable low-latency communications (URLLC).
Purpose & Motivation
The PDSCH was created to provide an efficient, flexible, and high-capacity mechanism for transmitting downlink data in packet-switched cellular systems. Earlier systems like GSM used dedicated timeslots for each user, which was inefficient for bursty data traffic. The shared channel concept, introduced with UMTS and refined in LTE and NR, allows statistical multiplexing of multiple users' data over a common pool of radio resources, dramatically improving spectral efficiency.
It solves the problem of how to dynamically allocate limited radio bandwidth to many users with varying and unpredictable data demands. By being scheduler-controlled, the PDSCH enables the network to prioritize traffic, manage interference, and adapt to fast-changing radio conditions. The evolution from a dedicated to a shared channel model was motivated by the need to support broadband internet access and multimedia services, requiring much higher data rates and more efficient resource utilization than circuit-switched or early packet-switched designs could offer.
Classification
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (66 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, several refinements were introduced for the PDSCH function, including corrections and clarifications for resource allocation procedures scheduled via PDCCH in common search space and for PDSCH mapping to virtual resource blocks. The release also addressed UE procedures for handling collisions, such as between dynamically scheduled and SPS PDSCH, and provided clarifications on aspects like TCI indication for multi-slot PDSCH, beam indication, and QCL assumptions for PDSCH received for RAR.
- CR on PDSCH mapping to virtual resource blocks TS 38.211CR0006
- Correction on PDSCH resource allocation scheduled by PDCCH in Type 0 common search space TS 38.211CR0018
- Clarification of reference to PDSCH processing capability 1 in TS 38.213 TS 38.213CR0042
- CR on sequential PDSCH and PUSCH scheduling TS 38.214CR0014
- CR on PDSCH beam indication TS 38.214CR0017
- Correction on TCI indication for multi-slot PDSCH TS 38.214CR0018
+ 7 more changes
In Release 16, key refinements to the PDSCH included corrections and enhancements for specific operational scenarios. These involved the HARQ-ACK codebook generation (including Type-3), processing timelines, and UE procedures for cases like dormancy indication without scheduled PDSCH. The release also provided corrections for PDSCH resource mapping, rate matching for SPS, and handling of collisions and QCL relations in multi-TRP and cross-carrier scheduling environments.
- Correction on DM-RS presence with PDSCH mapping type B TS 38.211CR0065
- CR to 38.213 on HARQ-ACK processing timeline for DCI format 1_1 with Scell dormancy indication without scheduling PDSCH TS 38.213CR0135
- Correction of NRU HARQ procedure in the presence of SPS PDSCH TS 38.213CR0163
- Type-1 HARQ-ACK for PDSCH repetition with different SCSs in DL and UL TS 38.213CR0180
- Correction for cancellation due to PDSCH/CSI-RS/SFI TS 38.213CR0186
- Correction of Type-3 HARQ-ACK codebook generation for a PDSCH with one transport block for a configuration with a maximum number of two TBs TS 38.213CR0187
+ 11 more changes
In Release 17, enhancements for the PDSCH focused on refining multi-PDSCH scheduling, HARQ-ACK feedback mechanisms, and operation in shared spectrum. Specific corrections and clarifications were introduced for scheduling via DCI format 4_1, handling collisions between SPS and dynamic PDSCHs for MBS, and the co-existence of FDMed unicast and group-common PDSCH. The release also provided updates for PDSCH processing timing in FR2-2 shared spectrum and clarified procedures for the first SPS PDSCH activation and HARQ-ACK transmission.
- CR on HARQ-ACK feedback for PDSCH scheduled by DCI format 4_1 TS 38.213CR0389
- CR on Type1 HARQ-ACK CB issue with more than one PDSCH per slot TS 38.213CR0474
- Correction on UE PDSCH processing procedure time for operation with shared spectrum channel access in FR2-2 in TS 38.214 TS 38.214CR0299
- CR on default QCL for unified TCI state for PDSCH and A-CSI-RS TS 38.214CR0314
- Correction on ZP CSI-RS rate-matching for multi-PDSCH scheduling TS 38.214CR0354
- Correction on DL PDSCH validity for multi-PDSCH scheduling via single DCI mTRP in FR2-2 TS 38.214CR0367
+ 5 more changes
In Release 18, key PDSCH enhancements included the introduction and refinement of multi-cell PDSCH scheduling for improved multi-TRP operation and the support for FDM reception of unicast and multicast PDSCH for UEs in the RRC_INACTIVE state. It also introduced specific provisions for multicast MBS PDSCH bandwidth for eRedCap devices and addressed beam collision issues between PDSCH and PDCCH in both S-DCI and M-DCI based multi-TRP schemes. Furthermore, the release clarified HARQ-ACK procedures for MsgB PDSCH, SPS PDSCH, and Rel-17 multi-PDSCH scheduling, while adding new test cases for PDSCH interference mitigation and PHY link adaptation.
- Introduction of multi-cell PDSCH / PUSCH scheduling TS 38.214CR0442
- Multicast MBS PDSCH bandwidth for eRedCap UE in RRC inactive state TS 38.213CR0629
- Corrections on multi-cell PDSCH / PUSCH scheduling TS 38.214CR0493
- CR on FDM reception of unicast and multicast PDSCH in RRC_INACTIVE state TS 38.214CR0517
- CR on PDSCH resource mapping for dedicated spectrum less than 5 MHz TS 38.214CR0518
- CR on Beam collision between PDSCH with offset less than a threshold and PDCCH in M-DCI based MTRP TS 38.214CR0620
+ 14 more changes
In Release 19, key enhancements for the PDSCH included the introduction of Msg4 PDSCH repetition and retransmission procedures and the introduction of SIB1 PDSCH repetition for FR1 TN. The release also featured corrections to existing mechanisms, specifically for PDSCH resource mapping, Hybrid Automatic Repeat Request (HARQ) Process Number (HPN) determination in multi-PDSCH scheduling, and Transport Block Size (TBS) determination for Semi-Persistent Scheduling (SPS) PDSCH.
- Correction on PDSCH resource mapping TS 38.211CR0178
- Correction on HPN determination for multi-PDSCH and multi-PUSCH scheduling TS 38.214CR0747
- Correction on TBS determination for SPS PDSCH TS 38.214CR0748
- Msg4 PDSCH repetition and retransmission TS 38.214CR0749
- Introduction of SIB1 PDSCH repetition for FR1 TN [Common_PDCCH_rep_TN] TS 38.300CR1085
Explore further
Broader topics and technologies where PDSCH plays a role.
Defining Specifications
3GPP specifications that define or reference PDSCH, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TS 25.202 vj00 | 7.68Mcps TDD Option Technical Specification | Rel-19 |
| TS 25.211 vj00 | UTRA FDD Layer 1: Transport & Physical Channels | Rel-19 |
| TS 25.213 vj00 | UTRA FDD Spreading and Modulation | Rel-19 |
| TS 25.214 vj00 | UTRA FDD Physical Layer Procedures | Rel-19 |
| TS 25.221 vj00 | UTRA TDD Physical Layer Specification | Rel-19 |
| TS 25.224 vj00 | UTRA TDD Physical Layer Procedures | Rel-19 |
| TS 25.225 vj00 | UTRA TDD Physical Layer Measurements | Rel-19 |
| TS 25.331 vj00 | UTRAN RRC Protocol Specification | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TS 25.430 vj00 | Introduction to Iub Interface Specifications | Rel-19 |
| TS 25.433 vj00 | Node B Application Part (NBAP) Protocol | Rel-19 |
| TS 25.435 vj00 | UTRAN Iub Interface User Plane Protocols | Rel-19 |
| TR 25.931 vj00 | UTRAN Signalling Procedures Examples | Rel-19 |
| TS 36.104 vj10 | Base Station (BS) radio transmission and reception | Rel-19 |
| TS 36.116 vj00 | E-UTRA Relay RF Requirements | Rel-19 |
| TS 36.117 vj00 | E-UTRA Relay RF Test Methods & Requirements | Rel-19 |
| TS 36.133 vj20 | E-UTRA RRM Requirements | Rel-19 |
| TS 36.141 vj00 | E-UTRA BS Conformance Testing | Rel-19 |
| TS 36.201 vj00 | LTE Physical Layer General Description | Rel-19 |
| TS 36.211 vj10 | LTE Physical Layer Specification | Rel-19 |
| TS 36.212 vj10 | LTE Multiplexing and Channel Coding | Rel-19 |
| TS 36.213 vj10 | LTE Physical Layer Procedures | Rel-19 |
| TS 36.216 vj00 | LTE Relay Node Physical Layer | Rel-19 |
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.302 vj00 | E-UTRA Physical Layer Services | Rel-19 |
| TS 36.306 vj00 | E-UTRA UE Radio Access Capability Parameters | Rel-19 |
| TS 36.747 ve00 | Enhanced CRS and SU-MIMO IM Performance Requirements | Rel-14 |
| TS 36.790 vf00 | LAA/eLAA for CBRS 3.5GHz Band in US | Rel-15 |
| TS 36.825 vd00 | Study on Additional LTE TDD Configurations | Rel-13 |
| TS 36.855 vd00 | E-UTRA Positioning Enhancements Study | Rel-13 |
| TS 36.863 vc00 | CRS Interference Mitigation for Homogeneous Networks | Rel-12 |
| TS 36.867 vd00 | LTE DL 4 Rx Antenna Port Study TR | Rel-13 |
| TR 36.976 vj00 | LTE-based 5G Terrestrial Broadcast Overview | Rel-19 |
| TS 37.107 vj00 | RF Requirements for LAA and NR-U Base Stations | Rel-19 |
| TS 37.857 vd10 | Study on Indoor Positioning Enhancements | Rel-13 |
| TR 37.901 vf10 | UE Application Layer Data Throughput Performance | Rel-15 |
| TR 37.911 vj00 | 3GPP 5G NTN Self-Evaluation Report | Rel-19 |
| TS 38.133 vj20 | 5G UE Radio Requirements for RRC_IDLE Mobility | 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 38.201 vj00 | NR Physical Layer General Description | Rel-19 |
| TS 38.202 vj00 | 5G NR Physical Layer Services | Rel-19 |
| TS 38.211 vj10 | NR Physical Channels and Modulation | Rel-19 |
| TS 38.212 vj10 | NR Multiplexing and Channel Coding | Rel-19 |
| TS 38.213 vj10 | NR Physical Layer Control Procedures | Rel-19 |
| TS 38.214 vj10 | NR Physical Layer Procedures for Data | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.521 vj20 | NR Physical Layer UE Conformance Testing | Rel-19 |
| TS 38.522 vj11 | UE Conformance Test Applicability Statement | Rel-19 |
| TS 38.523 vj20 | 5G NR UE Conformance Testing: Idle/Inactive | Rel-19 |
| TS 38.551 vi30 | User Equipment (UE) Multiple Input Multiple Output (MIMO) Over-the-Air (OTA) performance | Rel-18 |
| TR 38.808 vh00 | Study on NR above 52.6 GHz to 71 GHz | Rel-17 |
| TS 38.824 vg00 | NR URLLC Physical Layer Enhancements Study | Rel-16 |
| TR 38.830 vh00 | NR Coverage Enhancements Study | Rel-17 |
| TS 38.831 vg10 | UE RF Requirements for FR2 Enhancements | Rel-16 |
| TR 38.838 vh00 | Study on XR Evaluations for NR | Rel-17 |
| TR 38.869 vi00 | Study on low-power wake up signal and receiver for NR | Rel-18 |
| TR 38.878 vi40 | Technical Report on Advanced Receiver for MU-MIMO | Rel-18 |
| TR 38.889 vg00 | NR-based access to unlicensed spectrum study | Rel-16 |
| TR 38.903 vj00 | Test Tolerances & Measurement Uncertainties | Rel-19 |
| TS 45.820 vd10 | CIoT for Internet of Things | Rel-13 |
