Glossary
TTI (Transmission Time Interval) in 3GPP: meaning and where it is specified
At a glance
- Term
- TTI
- Stands for
- Transmission Time Interval
- Defined in
- 3GPP TS 25.302 V19.0.0, clause 7.1.5
- TR 21.905 also lists
- Transmission Timing Interval
- Used in
- TS 25.423, TS 25.433
In plain words
TTI is the interval separating Transport Block Set transfers by the physical layer over the radio interface. The specification describes MAC's role: "The MAC delivers one Transport Block Set to the physical layer every TTI." Both TS 25.423 and TS 25.433 use E-TTI to indicate the interval for E-DPCH operation.
Source: 3GPP TS 25.302 V19.0.0, clause 7.1.5. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.302/25302-j00.zip
Sources
- 3GPP TS 25.302 V19.0.0, clause 7.1.5. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.302/25302-j00.zip
- 3GPP TS 25.423 V19.0.0, clause 9.2.2.4J. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.423/25423-j00.zip
- 3GPP TS 25.433 V15.0.0, clause 18.1.2.55. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.433/25433-f00.zip
How this page was made
The facts box comes straight from the 3GPP TDoc list and specification archive as indexed by 3GPP Scout. An AI model (GPT-6 Luna) wrote the paragraph and named the source of each sentence. Code checked every quote word for word against the stored source text and every number against the cited source. A second AI model from another company (Claude Opus 5.5) reviewed the paragraph against the same sources. The 3GPP documents themselves govern.