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Glossary

IDFT (Inverse Discrete Fourier Transform) in 3GPP: meaning and where it is specified

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

At a glance

Term
IDFT
Stands for
Inverse Discrete Fourier Transform
Defined in
3GPP TR 21.905 V19.2.0, clause 4
Used in
TS 38.521-1, TS 38.521-2

In plain words

IDFT means "Inverse Discrete Fourier Transform", the expanded term listed in 3GPP TR 21.905. In E.4.1, IDFT-decoding preserves t and transforms f, representing allocated subcarriers, into g, representing demodulated symbols, with the same count. This usage appears in TS 38.521-1 and TS 38.521-2, both in clause E.4.1 on EVM.

Source: 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

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 38.521-1 V20.0.0, clause E.4.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/38_series/38.521-1/38521-1-k00.zip
  3. 3GPP TS 38.521-2 V19.4.0, clause E.4.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/38_series/38.521-2/38521-2-j40.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.