Description
The Physical Uplink Shared Channel (PUSCH) is a fundamental physical channel defined in 3GPP specifications for uplink transmission from the User Equipment (UE) to the network's base station (NodeB in UMTS, eNodeB in LTE, gNB in NR). It serves as the primary conduit for uplink user plane data, such as application data from a smartphone, and can also carry uplink control information (UCI) when configured to do so. The channel is termed 'shared' because its time-frequency resources are dynamically allocated by the network scheduler to different UEs, allowing for statistical multiplexing and efficient use of the available radio spectrum. This dynamic scheduling is a cornerstone of modern cellular systems, enabling them to adapt to varying traffic loads and channel conditions.
From a technical perspective, the PUSCH's operation is governed by a grant-based access mechanism. The UE must receive an uplink grant from the network, typically via a Downlink Control Information (DCI) message on the Physical Downlink Control Channel (PDCCH), before it can transmit. This grant specifies critical transmission parameters such as the allocated resource blocks (time and frequency), modulation and coding scheme (MCS), power control commands, and precoding information for MIMO. Upon receiving a valid grant, the UE processes its transport block (data) through a chain of physical layer procedures including channel coding (e.g., Turbo coding in LTE, LDPC in NR), scrambling, modulation (e.g., QPSK, 16QAM, 64QAM, 256QAM), layer mapping for MIMO, precoding, and finally mapping to the assigned resource elements on the OFDM (in LTE) or DFT-s-OFDM/CP-OFDM (in NR) waveform.
The architecture of the PUSCH is tightly integrated with other physical channels and signals. For instance, the Demodulation Reference Signal (DM-RS) is transmitted alongside the PUSCH within the same allocated resources to enable the base station to estimate the radio channel for coherent demodulation. The Sounding Reference Signal (SRS), transmitted separately, assists the network scheduler in understanding the uplink channel quality to make informed scheduling decisions. Furthermore, the PUSCH supports hybrid automatic repeat request (HARQ) with multiple parallel processes, allowing for rapid retransmissions in case of decoding failures, which is crucial for achieving high reliability and low latency. In 5G NR, the PUSCH design introduced greater flexibility, supporting multiple numerologies (subcarrier spacings), mini-slot-based transmissions for ultra-reliable low-latency communications (URLLC), and enhanced support for grant-free (configured grant) transmissions to reduce latency for periodic traffic.
Purpose & Motivation
The PUSCH was created to provide an efficient, flexible, and high-capacity mechanism for uplink data transmission in 3GPP systems, moving beyond the circuit-switched and dedicated channel paradigms of earlier 2G systems. Prior to shared channels, uplink resources were often statically assigned, leading to inefficient spectrum utilization when a user's data traffic was bursty or intermittent. The introduction of the shared channel concept, starting with the High-Speed Uplink Packet Access (HSUPA) enhancement in UMTS and fully realized in LTE, addressed this by allowing the network to dynamically allocate resources on a very short timescale (e.g., every 1 ms subframe in LTE) to only those users who actively have data to send.
This dynamic allocation solves the core problem of radio resource scarcity. By sharing the channel among many users based on instantaneous need, the PUSCH maximizes the overall system throughput and capacity. It also enables advanced radio features like link adaptation, where the modulation and coding scheme is adjusted based on the reported channel quality, and multi-user MIMO, where spatial layers are used to serve multiple users simultaneously on the same time-frequency resources. The evolution into 5G NR further refined its purpose to support a vastly wider range of services, from enhanced mobile broadband (eMBB) with very high data rates to massive Machine-Type Communications (mMTC) and Ultra-Reliable Low-Latency Communications (URLLC), necessitating features like grant-free access and support for diverse numerologies.
Classification
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (63 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, new PUSCH capabilities and corrections were introduced, including performance and demodulation requirements for subslot and shortened TTI (sTTI) operations. The release also specified corrections for procedures like PUSCH with configured grant, transmissions scheduled by a Random Access Response (RAR) UL grant, and UCI reporting with beta_offset values in PUSCH. Furthermore, it addressed clarifications for scrambling, power scaling, and slot configuration, while introducing a burst model for eLAA PUSCH demodulation.
- Performance requirements for subslot-PUSCH TS 36.104CR4800
- Introduction of PUSCH demodulation requirements for sTTI TS 36.104CR4803
- Correction on the partial PUSCH mode field for FeLAA in 36.212 TS 36.212CR0300
- Correction on physical resource mapping for PUSCH with configured grant TS 38.211CR0008
- Corrections on PUSCH scheduled by RAR UL grant and Msg3 PUSCH retransmission TS 38.211CR0016
- Correction on PUSCH scrambling TS 38.211CR0017
+ 7 more changes
In Release 16, key enhancements for PUSCH included the introduction and finalization of performance requirements for an enhanced High-Speed Train (HST) scenario. The release also introduced procedures for handling collisions and multiplexing, such as for overlapping PUCCH/PUSCH transmissions with different priorities and the multiplexing of SL HARQ-ACK information on a PUSCH. Furthermore, it provided corrections and clarifications for various existing procedures, including PUSCH repetition Type B, PUSCH processing for DAPS handover, and PUSCH retransmission power control for RAR UL grants.
- CR to 36.104 on LTE HST PUSCH conditions TS 36.104CR4873
- CR to TS 36.104: Introduction of PUSCH performance requirements for enhanced HST scenario TS 36.104CR4883
- CR to TS 36.104 Updates of PUSCH performance requirements for enhanced HST scenario TS 36.104CR4891
- CR to TS 36.104 Finalization on PUSCH performance requirements for enhanced HST scenario TS 36.104CR4895
- PUR correction on PUSCH Repetition Adjustment and Zero Padding Procedures TS 36.212CR0361
- Correction on channel inference assumption for PUSCH repetition Type B TS 38.211CR0070
+ 11 more changes
In Release 17, key enhancements for the PUSCH included improved support for multi-TRP (mTRP) operations with specific power control parameters and Power Headroom Reporting (PHR) for mTRP PUSCH repetitions. The release also introduced clarifications and corrections for collision handling, such as resolving conflicts between high-priority dynamic grant and low-priority configured grant PUSCH, and for multiplexing procedures including HARQ-ACK codebooks on PUSCH. Furthermore, refinements were made to scheduling mechanisms like the Time Domain Resource Allocation (TDRA) for multiple PUSCH scheduling and the default parameters for parallel transmission scenarios involving PRACH with SRS, PUCCH, or PUSCH.
- CR on the description of the SRS resource set indication for PUSCH repetition TS 38.212CR0117
- Correction on TDRA for multiple PUSCH scheduling in TS 38.212 TS 38.212CR0127
- CR on default PUSCH power control parameters for mTRP PUSCH TS 38.213CR0344
- CR for power control of mTRP PUSCH repetition TS 38.213CR0345
- CR on HP DG PUSCH and LP CG PUSCH collision resolution TS 38.213CR0355
- Correction on parallel transmission of PRACH and SRS/PUCCH/PUSCH TS 38.213CR0386
+ 9 more changes
In Release 18, key enhancements for PUSCH included the introduction of a reference signal for pathloss determination specifically for Type 1 Configured Grant PUSCH and the new capability to multiplex HARQ-ACK feedback on a PUSCH with repetitions, even when the associated downlink assignments were received after the uplink grant. The release also provided corrections and clarifications for several procedures, including HARQ-ACK multiplexing on PUSCH repetitions, PUSCH retransmission for Configured Grant RACH-less handover, and the support for simultaneous PUCCH and PUSCH transmission of the same priority in uplink carrier aggregation.
- Introduction of RS for pathloss determination of Type 1 CG PUSCH [PL RS Type 1 CG] TS 38.213CR0567
- Introduction of multiplexing in a PUSCH with repetitions HARQ-ACK associated with DL assignments received after an UL grant for the PUSCH [HARQ-ACK MUX on PUSCH] TS 38.213CR0568
- Clarification on not multiplexing UCI on MSG3 PUSCH TS 38.213CR0631
- Correction on multiplexing HARQ-ACK in a PUSCH transmission TS 38.213CR0636
- Correction on PUSCH retransmission for CG RACH-less handover TS 38.213CR0638
- Correction on HARQ-ACK multiplexing on a PUSCH repetition [HARQ-ACK MUX on PUSCH] TS 38.213CR0646
+ 10 more changes
In Release 19, a key enhancement for the PUSCH was the introduction of multiplexing the UEIRI (Uplink Early Interference Report Indicator) into the channel. This change was specified across both the physical channel coding description (TS 38.212) and the physical layer procedures for control (TS 38.213). The update defines how this interference report is integrated into the PUSCH transmission structure.
Explore further
Broader topics and technologies where PUSCH plays a role.
Defining Specifications
3GPP specifications that define or reference PUSCH, 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 25.221 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 25.402 vj00 | UTRAN Synchronisation Mechanisms | 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 36.201 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 36.790 vf00 | LAA/eLAA for CBRS 3.5GHz Band in US | Rel-15 |
| TS 36.878 vd00 | LTE Performance Enhancements for High Speed Scenarios | Rel-13 |
| TS 36.884 vd10 | MMSE-IRC Receiver Performance for LTE BS | Rel-13 |
| TS 37.106 vj00 | UE RF Requirements for Shared Spectrum Access | Rel-19 |
| 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 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.521 vj20 | NR Physical Layer UE Conformance Testing | Rel-19 |
| TS 38.523 vj20 | 5G NR UE Conformance Testing: Idle/Inactive | Rel-19 |
| 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 |
| 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 38.889 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 |
