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Glossary

TTI (Transmission Timing Interval) in 3GPP: meaning and where it is specified

Published 2026-10-16Updated 2026-10-16

At a glance

Term
TTI
Stands for
Transmission Timing Interval
Defined in
3GPP TR 21.905 V19.2.0, clause 4
Used in
TS 25.302, TS 25.423

In plain words

The vocabulary entry in 3GPP TR 21.905 V19.2.0 expands TTI as Transmission Timing Interval. In TS 25.302, the MAC delivers "one Transport Block Set" to the physical layer every TTI. In TS 25.423, E-TTI indicates the Transmission Time Interval for E-DPCH operation.

Source: 3GPP TS 25.302 V18.0.0, 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-i00.zip

Sources

  1. 3GPP TR 21.905 V19.2.0, clause 4. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/21_series/21.905/21905-j20.zip
  2. 3GPP TS 25.302 V18.0.0, 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-i00.zip
  3. 3GPP TS 25.423 V15.0.0, 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-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.