TS 38.321 – NR MAC Protocol Specification
3GPP TS 38.321 is the 3GPP Technical Specification for NR MAC Protocol Specification. Its official 3GPP title is “Medium Access Control (MAC) protocol specification”. It is published in 5 releases (Rel-15 to Rel-19); the latest version is 19.4.0 in Rel-19.
Defines the 5G NR Medium Access Control (MAC) protocol, covering procedures such as random access, scheduling, HARQ, DRX, and sidelink, plus features for NTN, IAB, NCR, and LTM.
Releases and versions of TS 38.321
| Release | Latest version | Links |
|---|---|---|
| Rel-19 | 19.4.0 | Read · Download (3GPP) |
| Rel-18 | 18.10.0 | Read · Download (3GPP) |
| Rel-17 | 17.15.0 | Read · Download (3GPP) |
| Rel-16 | 16.22.0 | Read · Download (3GPP) |
| Rel-15 | 15.14.0 | Read · Download (3GPP) |
Scope of TS 38.321
Category: Radio Access (MAC Layer). Technology generation: 5G. Network layer: RAN.
Who should read this specification?
- Network operators
- Device manufacturers
- Researchers and academics
Implementation notes
Complexity level: Expert. Implementation difficulty: High.
Key technologies
Excerpt from TS 38.321
1 Scope
The present document specifies the NR MAC protocol.
Excerpt from the official 3GPP document (Rel-19). Read the full specification with interactive table of contents.
Specifications referenced by TS 38.321
- TS 38.133 NR Radio Resource Management Requirements
- TS 36.133 LTE Radio Resource Management Requirements
- TS 26.114 IMS Multimedia Telephony Client
- TS 38.101 UE Radio Transmission and Reception
- TS 36.213 LTE Physical Layer Procedures
- TS 37.213 Shared Spectrum Physical Layer Procedures
- TS 23.287 5G V2X Architecture Enhancements
- TR 21.905 3GPP Terminology and Definitions
- TS 23.285 V2X Architecture Enhancements for LTE
- TS 36.331 E-UTRA Radio Resource Control (RRC) Protocol
- TS 36.321 E-UTRA MAC Protocol Specification
- TS 37.355 LTE Positioning Protocol (LPP)
Specifications that reference TS 38.321
- TS 23.501 5G System Architecture
- TS 24.229 IMS SIP/SDP Call Control Protocol
- TS 23.228 IP Multimedia Core Network Subsystem
- TS 38.300 NR and NG-RAN Overall Description
- TS 38.331 NR Radio Resource Control (RRC)
- TS 26.114 IMS Multimedia Telephony Client
- TS 24.501 5GS NAS Protocol Specification
- TS 28.622 Generic Network Resource Information Service
- TS 32.422 Trace, MDT and UE Measurement Control
- TS 28.552 5G Network Performance Measurements
- TS 28.554 5G End-to-End KPI Definitions
- TS 36.321 E-UTRA MAC Protocol Specification
Other specifications in the 38 series
- TS 38.305 NG-RAN UE Positioning Stage 2
- TS 38.306 NR UE Radio Access Capability Parameters
- TS 38.307 Release-Independent NR UE Requirements
- TS 38.314 NR Performance Measurements Specification
- TS 38.322 NR Radio Link Control (RLC) Protocol Specification
- TS 38.323 PDCP Protocol Specification
- TS 38.331 NR Radio Resource Control (RRC)
- TS 38.340 Backhaul Adaptation Protocol (BAP) Specification
Frequently asked questions
What is 3GPP TS 38.321?
3GPP TS 38.321 is the 3GPP Technical Specification for NR MAC Protocol Specification. Defines the 5G NR Medium Access Control (MAC) protocol, covering procedures such as random access, scheduling, HARQ, DRX, and sidelink, plus features for NTN, IAB, NCR, and LTM.
Which 3GPP releases include TS 38.321?
TS 38.321 is published in 5 releases, from Rel-15 to Rel-19. The latest version on 3GPP Explorer is 19.4.0 (Rel-19).
What category does TS 38.321 belong to?
TS 38.321 belongs to the Radio Access (MAC Layer) category of 3GPP specifications. It applies to 5G networks.
View the full specification with interactive table of contents, version history, and AI analysis.
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