Description
The Physical Sidelink Control Channel (PSCCH) is a critical control channel in the 3GPP sidelink (SL) radio interface, operating at the physical layer. Its primary function is to carry Sidelink Control Information (SCI), specifically the scheduling assignment (SA), from a transmitting User Equipment (UE) to one or more receiving UEs. The SCI transmitted on the PSCCH provides the necessary decoding information for the associated data transmission on the Physical Sidelink Shared Channel (PSSCH). This information includes the detailed resource allocation (time and frequency resources) for the PSSCH, the Modulation and Coding Scheme (MCS), group destination ID, timing advance information, and other parameters related to the HARQ process and retransmissions.
Architecturally, the PSCCH and PSSCH are tightly coupled in a time-division manner within a sidelink subframe or slot. In LTE sidelink (Mode 3 and Mode 4), the PSCCH typically occupies the first symbols of a subframe, followed by the PSSCH in the remaining symbols of the same subframe. The transmitting UE selects resources for the PSCCH (and thus implicitly for the associated PSSCH) either based on a grant from the network (Mode 3) or through a distributed sensing-based autonomous selection algorithm (Mode 4). The PSCCH itself is transmitted using a specific demodulation reference signal (DM-RS) pattern to allow the receiving UE to perform channel estimation for coherent demodulation.
In NR sidelink (introduced in Release 16), the PSCCH design is more flexible to accommodate the wide range of numerologies, bandwidths, and use cases (e.g., V2X, public safety, commercial D2D). NR sidelink defines two stages of SCI: SCI Format 0-1, which is carried on the PSCCH, and SCI Format 0-2, which can be carried on the PSSCH itself. The first-stage SCI on the PSCCH contains the information absolutely required for a UE to know if it should attempt to decode the PSSCH (e.g., priority, resource reservation, frequency resource assignment). The detailed MCS, HARQ information, and source/destination IDs are then carried in the second-stage SCI on the PSSCH. This two-stage approach improves efficiency and flexibility. The PSCCH in NR can be configured within dedicated resource pools, and its transmission can be based on sensing results (similar to LTE Mode 4) or network scheduling (Mode 1).
Purpose & Motivation
The PSCCH was introduced to enable scheduled and efficient direct communication between devices in sidelink. Without a dedicated control channel, sidelink communication would be chaotic and inefficient. Devices would have no way to announce their impending data transmissions or to describe how that data should be received. The PSCCH solves this problem by providing a structured, in-band signaling mechanism that allows a transmitting UE to inform nearby UEs about the parameters of its following data transmission.
Its creation was motivated by the need for reliable, scalable, and interference-managed Device-to-Device communication. In early ad-hoc communication schemes (like some pre-standard V2X or public safety solutions), control information was either piggybacked on data or sent in a blind fashion, leading to high collision probability and poor resource utilization. The PSCCH, especially when combined with sensing procedures (as in LTE Mode 4 and NR Mode 2), allows UEs to listen to the channel before transmitting, select resources that are likely to be free, and announce their resource usage to others. This dramatically reduces interference and enables predictable latency—critical for safety-related V2X messages and public safety communications. It is the mechanism that transforms simple broadcast into a managed, resource-controlled direct link.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (124 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-12, normative work from Rel-15.
In Release 15, specific RF performance requirements for the PSCCH were newly introduced for V2X sidelink communication. This included defining the applicable channel bandwidths per operating band and the corresponding UE maximum output power for modulation and channel bandwidth for V2X. These additions provided the necessary physical layer foundation for the enhanced sidelink control channel in vehicular use cases.
- Clarification on CRC attachment for DL-SCH and PCH transport channels in NB-IoT TS 36.212CR0285
- Correction on V2X sidelink communication in TS 36.300 TS 36.300CR1199
- 36.300 CR on Correction of Physical Layer Resource to Cell Resource TS 36.300CR1211
- Minor corrections to services provided by physical layer TS 36.302CR1195
- Correction on MCS for V2X sidelink communication in TS 36.302 TS 36.302CR1196
- Correction on physical downlink control channel TS 38.213CR0020
+ 11 more changes
In Release 16, the PSCCH was fundamentally enhanced as part of introducing 5G V2X with NR Sidelink, moving beyond the LTE-based design. Key new aspects included support for operation in shared spectrum with defined channel access procedures and Listen-Before-Talk (LBT) types, as detailed in the physical layer specifications. Furthermore, specific corrections and clarifications were made to the sidelink physical layer procedures and power control mechanisms to ensure reliable operation for advanced V2X services.
- Introduction of 5G V2X with NR Sidelink TS 36.300CR1271
- Introduction of 5G V2X sidelink features into TS 38.212 TS 38.212CR0025
- Introduction of Physical Layer Enhancements for NR URLLC TS 38.212CR0026
- Introduction of shared spectrum channel access TS 38.213CR0071
- Correction for NR sidelink communication TS 36.300CR1287
- Clarification on LTE DAPS and sidelink on 36.300 TS 36.300CR1338
+ 41 more changes
In Release 17, specific enhancements for the PSCCH function included clarifications on the timeline for transmitting and receiving the associated PSFCH with control information. Furthermore, procedures were defined for a UE to report sidelink HARQ-ACK on the uplink for specific Sidelink Configured Grant transmissions, integrating sidelink and uplink feedback. These updates refined the control channel procedures to support more reliable and coordinated sidelink communication.
- Introduction of Rel-17 sidelink enhancements TS 37.985CR0001
- Introduction of NR sidelink enhancement TS 38.212CR0094
- Introduction of sidelink enhancements in NR TS 38.213CR0279
- Introduction of Rel-17 sidelink enhancements and concurrent Uu-PC5 bands TS 37.985CR0004
- Corrections on NR sidelink enhancement in 38.212 TS 38.212CR0100
- CR on ChannelAccess-Cpext in Fallback DCI TS 38.212CR0118
+ 21 more changes
In Release 18, the PSCCH function was enhanced as part of the broader NR sidelink evolution, which introduced new capabilities including sidelink carrier aggregation (CA) and dynamic resource pool sharing for NR V2X. These advancements were complemented by the introduction of specific sidelink channel access procedures to manage radio resources more efficiently. The release also included necessary corrections and maintenance for the overall NR sidelink evolution framework to ensure robust operation.
- Introduction of sidelink CA and dynamic resource pool sharing for NR V2X TS 37.985CR0007
- Introduction of sidelink channel access procedures for Rel-18 NR sidelink evolution TS 38.201CR0003
- Introduction of Rel-18 network-controlled repeaters TS 38.201CR0004
- Introduction of Rel-18 NR sidelink evolution TS 38.212CR0149
- Introduction of Rel-18 network controlled repeaters TS 38.212CR0150
- Introduction of Network Controlled Repeaters TS 38.213CR0506
+ 22 more changes
In Release 19, the PSCCH function was updated through the adaptation of common channels and signals for New Radio Sidelink (NES), which included corrections to ensure proper operation. Furthermore, a new 3MHz channel bandwidth was formally added to the applicable channel arrangements for sidelink communication, as specified in TR 38.863. These changes refined the channel's configuration and expanded its supported bandwidth options.
- Addition of the 3MHz channel to TR 38.863 TS 38.863CR0036
- Corrections on R19 NES adaptation of common channel/signals TS 38.212CR0243
- Corrections on R19 NES adaptation of common channel/signals TS 38.213CR0753
- TR 38.787 under change control TS 38.787
- Approved by plenary – Rel-19 spec under change control TS 38.793
Explore further
Broader topics and technologies where PSCCH plays a role.
Defining Specifications
3GPP specifications that define or reference PSCCH, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 36.101 vj30 | LTE UE Radio Transmission & Reception 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 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.302 vj00 | E-UTRA Physical Layer Services | Rel-19 |
| TS 36.785 ve00 | LTE Sidelink V2V Services Study | Rel-14 |
| TS 36.786 ve00 | TR on V2X Services based on LTE sidelink | Rel-14 |
| TS 36.787 vf00 | V2X New Band Combinations for LTE | Rel-15 |
| TS 36.788 vf00 | V2X Phase 2 Technical Report for LTE | Rel-15 |
| TS 36.877 vc00 | LTE Device to Device Proximity Services | Rel-12 |
| TR 37.985 vj00 | Overview of V2X features in LTE and NR | Rel-19 |
| TS 38.101 vj31 | NR User Equipment Radio Transmissions | Rel-19 |
| TS 38.201 vj00 | NR Physical Layer General Description | 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 38.521 vj20 | NR Physical Layer UE Conformance Testing | Rel-19 |
| TR 38.785 vh00 | UE radio transmission for enhanced NR sidelink | Rel-17 |
| TR 38.786 vi20 | Technical Report for NR Sidelink Evolution | Rel-18 |
| TS 38.787 vj00 | UE Radio Transmission for Sidelink CA in ITS Band | Rel-19 |
| TS 38.793 vj00 | Simultaneous Rx/Tx Band Combinations TR | Rel-19 |
| TR 38.839 vh00 | Simultaneous Rx/Tx band combinations | Rel-17 |
| TS 38.863 vj10 | NR NTN RF and Co-existence Spec | Rel-19 |
| TR 38.868 vh00 | Optimizations of pi/2 BPSK uplink power in NR | Rel-17 |
| TR 38.881 vi00 | Technical Report on Lower MSD for Inter-band CA/EN-DC/DC | Rel-18 |
| TR 38.886 vg30 | NR V2X UE Radio Transmission & Reception | Rel-16 |
| TR 38.889 vg00 | NR-based access to unlicensed spectrum study | Rel-16 |
| TR 38.894 vi00 | Technical Report | Rel-18 |