- What it is: LTE-based 5G Broadcast, a one-way system for delivering linear TV and radio to receivers with no SIM or return channel.
- Why it matters: It lets broadcasters reach devices over a broadcast physical layer, without per-user connections.
- In this section: This page covers how a receiver acquires a cell, the numerologies and bandwidths, and the features by release.
How it works
A 5G Broadcast receiver has to bootstrap itself from nothing: there's no SIM, no return channel, and no prior connection to the network. LTE-based 5G Broadcast is a one-way physical layer built on the LTE TS 36.xxx series, a receiver acquires the cell, reads the broadcast control information, then decodes the multicast traffic channel, with no uplink and no per-user state (ETSI TS 103 720 V1.2.1 clause 7.2; ETSI TS 103 720 V1.2.1 clause 7.3.1; TR 36.976 V19.0.0 clause 1; ETSI TS 103 720 V1.2.1 clause 6.4.6).
Key specifications: ETSI TS 103 720 (5G Broadcast System for linear TV and radio), 3GPP TR 36.976 (LTE-based 5G broadcast overview), 3GPP TS 26.346 (MBMS protocols and codecs), 3GPP TS 26.347 (MBMS application programming interface) (ETSI TS 103 720 V1.2.1 clause 1; TS 26.346 V19.3.0 clause 1; TS 26.347 V19.0.0 clause 1).
PMCH (Physical Multicast Channel) carries the broadcast payload; in an MBMS-dedicated cell it occupies almost the whole carrier. CAS (Cell Acquisition Subframe) is the entry point, non-MBSFN subframes transmitted with a 40 ms periodicity (MIB-MBMS in subframe 0 of radio frames with SFN mod 4 == 0) use 15 kHz SCS with a normal or extended cyclic prefix and carry PSS, SSS, PBCH, PDCCH and PDSCH (PCFICH when the CFI is not given in MIB-MBMS), letting the receiver synchronise and decode MIB-MBMS (on PBCH) and SIB1-MBMS without a USIM (ETSI TS 103 720 V1.2.1 clause 6.4.2; TS 36.331 V19.4.0 clause 5.2.1.2; ETSI TS 103 720 V1.2.1 clause 7.2). For 6, 7 and 8 MHz PMCH bandwidths the CAS occupies a narrow 15 or 25 PRB (3 or 5 MHz), so the receiver bootstraps narrow and the SIBs then point it at the wider PMCH (ETSI TS 103 720 V1.2.1 clause 7.3.2; TS 36.300 V19.2.0 clause 5.1.1). MCCH (Multicast Control Channel) carries the MBSFN (Multicast-Broadcast Single-Frequency Network) area configuration, which services map to which PMCH, MCS, scheduling, and is re-read at each modification-period boundary so the receiver can pick up transmitter-side changes. MTCH (Multicast Traffic Channel) is the logical channel that maps the user-service data onto PMCH (TS 36.300 V19.2.0 clause 5.0; ETSI TS 103 720 V1.2.1 clause 6.4.2; ETSI TS 103 720 V1.2.1 clause 11.3.1; ETSI TS 103 720 V1.2.1 clause 7.3.2; ETSI TS 103 720 V1.2.1 clause 5.5.4; TS 36.300 V19.2.0 clause 5.1.1; TS 36.331 V19.4.0 clause 5.8.1.3; TS 36.331 V19.4.0 clause 6.2.2; TS 36.300 V19.2.0 clause 15.3.5; TS 36.300 V19.2.0 clause 6.1.2.2; TS 36.300 V19.2.0 clause 6.1.3.2; TS 36.300 V19.2.0 clause 15.2.1).
Acquisition order on the receiver, step by step:
- Synchronise on PSS/SSS in the CAS (ETSI TS 103 720 V1.2.1 clause 7.3.2).
- Decode PBCH to get MIB-MBMS (bandwidth, SFN, semi-static CFI) (TS 36.331 V19.4.0 clause 6.2.2).
- Decode SIB1-MBMS (cell access, SI scheduling) (TS 36.331 V19.4.0 clause 6.2.2).
- Decode SIB13 (MBSFN area info, MCCH configuration, PMCH bandwidth) (TS 36.331 V19.4.0 clause 6.3.1; TS 36.331 V19.4.0 clause 6.3.7; TS 36.331 V19.4.0 clause 6.2.2).
- Decode MCCH (TS 36.331 V19.4.0 clause 5.8.2).
- Decode PMCH/MTCH, the receiver is now showing the channel (ETSI TS 103 720 V1.2.1 clause 7.3.4; TS 36.300 V19.2.0 clause 15.3.3).
Numerologies (subcarrier spacings)
The choice of subcarrier spacing (SCS) trades cyclic-prefix length (and therefore maximum SFN reach and mobility tolerance) against overhead (ETSI TS 103 720 V1.2.1 clause 5.13; ETSI TS 103 720 V1.2.1 table 6.4.4-1; ETSI TS 103 720 V1.2.1 clause 10.3). The full set profiled by ETSI TS 103 720 is:
| SCS | 3GPP release | Cyclic prefix (approx.) | Primary use case |
|---|---|---|---|
| 15 kHz | (LTE baseline) | 16.6 microseconds (PMCH); normal or extended (CAS) | CAS; PMCH in MBSFN subframes (ETSI TS 103 720 V1.2.1 table 6.4.4-1; clause 6.4.2) |
| 7.5 kHz | Rel-14 (TS 36.331 V19.4.0 clause 6.3.7; TR 21.914 V14.0.0 clause 9.2.2) | ~33 microseconds | not stated in the sources read (ETSI TS 103 720 V1.2.1 table 6.4.4-1) |
| 1.25 kHz | Rel-14 (TR 21.914 V14.0.0 clause 9.2.2) | ~200 microseconds | larger-than-cellular inter-site distance, low-to-moderate mobility (TR 36.976 V19.0.0 clause 4.3) |
| 2.5 kHz | Rel-16 | ~100 microseconds | mobile reception (up to ~250 km/h) |
| 0.37 kHz | Rel-16 | ~300 microseconds | very large SFN (inter-site distance up to 125 km) (ETSI TS 103 720 V1.2.1 clause 5.13; TR 36.976 V19.0.0 clause 4.2) |
The 0.37 kHz numerology uses a 3 ms slot structure and defines two reference-signal placement variants selected by timeSeparation (sl2 and sl4); this is signalled per MBSFN area in MBSFN-AreaInfo-r16 (TS 36.331). The MBSFN reference-signal patterns for each numerology are defined in TS 36.211 clause 6.10.2.2 (TS 36.211 V19.3.0 clause 4.1; TS 36.331 V19.4.0 clause 6.3.7; ETSI TS 103 720 V1.2.1 clause 11.3.1; TS 36.211 V19.3.0 clause 6.10.2.2).
Channel bandwidths
The PMCH can use the standard LTE bandwidths (up to 20 MHz) carried in MIB-MBMS, or the UHF broadcast bandwidths added in Release 17 and signalled by pmch-Bandwidth-r17 in SIB13: (TS 36.331 V19.4.0 clause 6.2.2; TS 36.331 V19.4.0 clause 6.3.7; TS 36.331 V19.4.0 clause 6.3.1; TR 36.976 V19.0.0 clause 4.3; ETSI TS 103 720 V1.2.1 clause 8)
| pmch-Bandwidth-r17 | Bandwidth | PRB |
|---|---|---|
n30 (TS 36.331 V19.4.0 clause 6.3.7; ETSI TS 103 720 V1.2.1 clause 7.3.2) | 6 MHz | 30 |
n35 (TS 36.331 V19.4.0 clause 6.3.7; ETSI TS 103 720 V1.2.1 clause 7.3.2) | 7 MHz | 35 |
n40 (TS 36.331 V19.4.0 clause 6.3.7; ETSI TS 103 720 V1.2.1 clause 7.3.2) | 8 MHz | 40 |
When present, pmch-Bandwidth-r17 overrides the narrowband CAS bandwidth for the PMCH region; its absence means the legacy LTE bandwidth applies. See Operational Parameters in Use for the values observed in practice (TS 36.300 V19.2.0 clause 5.1.1; TS 36.331 V19.4.0 clause 6.3.7; TS 36.213 V19.5.0 clause 11.1).
Specifications by 3GPP release
The Release 14 to Release 17 features below are profiled by ETSI TS 103 720 V1.2.1; the Release 18 and Release 19 features are not (ETSI TS 103 720 V1.2.1 clause 4.3.2). For the standards-tracking narrative with the version-to-release mapping and the release-by-release table, see Standards: Media delivery over 5G Broadcast.
Release 14 (enTV baseline). The foundation: the MBMS-dedicated cell (almost 100% of the carrier for broadcast), the 1.25 kHz numerology (cyclic prefix of 200 microseconds, symbol duration of 1 ms), the CAS frame structure, 256-QAM on PMCH (available since Release 12) and the broadcast control blocks MIB-MBMS (MasterInformationBlock-MBMS-r14, on PBCH) and SIB1-MBMS (SystemInformationBlockType1-MBMS-r14) (TR 21.914 V14.0.0 clause 9.2.2; TR 36.976 V19.0.0 clause 4.2; ETSI TS 103 720 V1.2.1 clause 5.13). Shorter MCCH repetition and modification periods (down to one radio frame) support faster system-information updates (TS 36.331 V19.4.0 clause 6.3.7).
Release 16 (LTE-based 5G Terrestrial Broadcast, normative). The normative work item adds the 2.5 kHz and 0.37 kHz numerologies and their reference-signal patterns, PDCCH Format 4 (aggregation level 16) for robust control-channel reception, PBCH repetition within the CAS to increase PBCH robustness, the MBSFN-AreaInfo-r16 structure (carrying subcarrierSpacingMBMS-r16 and timeSeparation-r16), the semi-static CFI in MIB-MBMS (semiStaticCFI-MBMS-r16), and Receive-Only Mode (ROM) information (MBMS-ROM-Info-r16, carried in MBMSInterestIndication) with which a UE reports the carrier frequency, subcarrier spacing and bandwidth on which it receives MBMS in ROM (TR 36.976 V19.0.0 clause 4.3; TS 36.211 V19.3.0 clause 6.8.1; TS 36.211 V19.3.0 clause 6.6.4.1; TS 36.331 V19.4.0 clause 6.3.7; TS 36.331 V19.4.0 clause 6.2.2; TS 36.331 V19.4.0 clause 5.8.5.4).
Release 17 (channel bandwidths). Adds the 6/7/8 MHz PMCH bandwidths (30/35/40 PRB) via pmch-Bandwidth-r17, with updated TBS and PMCH resource-allocation tables. This is the release profiled by the published ETSI TS 103 720 v1.2.1 (June 2023), which also defines the Base, Main and 5GMS receiver categories (TR 36.976 V19.0.0 clause 4.3; TS 36.331 V19.4.0 clause 6.3.7; ETSI TS 103 720 V1.2.1 clause 7.3.2; ETSI TS 103 720 V1.2.1 clause 4.3.2; ETSI TS 103 720 V1.2.1 table 10.1-1).
Release 18 (UHF bands, receive-only). A spectrum-layer change only: the receive-only (downlink-only) UHF bands Band 107 (612 to 652 MHz) and Band 108 (470 to 698 MHz), defined as standalone downlink-only (SDO) bands in Table 5.5H-1 of TS 36.101, with base-station requirements in TS 36.104; TS 36.307 makes the SDO broadcast bands release-independent from Release 17. There are no new numerologies; the Release 18 changes to the MBMS text of TS 36.331 are corrections only (TR 36.976 V19.0.0 clause 4.3; TS 36.331 V19.4.0 annex H). The published ETSI TS 103 720 v1.2.1 does not yet include specific frequency bands; its clause 8 defers them to a future revision (TS 36.101 V20.1.0 clause 5.5H; TS 36.101 V20.1.0 table 5.5H-1; TS 36.104 V19.2.0 clause 5.5; TS 36.307 V20.0.0 clause 3A; ETSI TS 103 720 V1.2.1 clause 8).
Release 19 (PMCH Phase 2, CAS muting, new bands). PMCH Phase 2 adds time interleaving (a TBS scaling factor N and a separation M, in MBSFN subframes, between successive transmissions of the same transport block), frequency interleaving, a PMCH cyclic shift (pmch-CyclicShiftAlpha) and extended MCH scheduling periods, all carried in new v1900 RRC extensions (TS 36.331 V19.4.0 clause 6.3.7; TS 36.213 V19.5.0 clause 11.1; TS 36.211 V19.3.0 clause 6.5.1). The PMCH-specific MCS tables (TS 36.213 clause 11.1, Tables 11.1-1 and 11.1-2, the latter extending to 256-QAM) already exist in the Release 18 version of TS 36.213. CAS muting frees synchronisation-channel airtime for PMCH by transmitting PSS/SSS/PBCH only in the active part of each period (cas-MutingConfig-r19 in the new SystemInformationBlockType1-MBMS-v1900 extension). Two further receive-only UHF bands, Band 112 (470 to 608 MHz) and Band 113 (606 to 698 MHz), are defined in Table 5.5H-1 of TS 36.101 and are release-independent from Release 17. These features postdate the published ETSI TS 103 720 v1.2.1 and are not profiled by it (TS 36.211 V19.3.0 annex A; TS 36.101 V20.1.0 annex J; TS 36.213 V19.5.0 clause 11.1; TS 36.213 V18.4.0 clause 11.1; TS 36.211 V19.3.0 clause 6.6.4; TS 36.211 V19.3.0 clause 6.11.1.2; TS 36.211 V19.3.0 clause 6.11.2.2; TS 36.331 V19.4.0 clause 6.2.2; TS 36.101 V20.1.0 table 5.5H-1; TS 36.307 V20.0.0 clause 3A; TS 36.307 V20.0.0 annex A).
Service layer (SA4), by release. Above the radio, the MBMS service layer is specified in TS 26.346, TS 26.347 and TS 26.348. Release 15 added a SAND mode and hybrid (unicast-supplemented) MBMS services, an HDR TV video profile, VR profiles, and FEC and ROHC for MBMS (TR 21.915 clauses 12.5.3, 12.4.2, 12.4.3 and 12.4.4). Release 16 moved the xMB API into TS 26.348 and added service interactivity for DASH-over-MBMS (TR 21.916 clauses 9.1 and 20.1). Release 17 added extensions for 5G Media Streaming via eMBMS (TR 21.917 clause 6.3.4.3.3). Release 19 added in-session unicast repair for MBMS object distribution and improved time synchronisation (TS 26.346 V19.3.0 change history, CR 0677 and CR 0672; TR 21.919 clause 11.6). Release 19 also defines a new band for 5G broadcast over a geosynchronous satellite, Band 246 (1467 to 1492 MHz, downlink only, ITU Region 3), with UE requirements for a 10 MHz PMCH in TS 36.102 and Satellite Access Node requirements in TS 36.108 (TR 21.919 clause 5.4.1). For Release 20, the 3GPP work plan of 28 September 2026 lists one work item for LTE-based 5G Broadcast, LTE_band_246_5G_bcast_GSO_BWs (new channel bandwidths for Band 246), in RAN WG4.
5G-MAG's own reference tools overview slide deck summarises the transmitter and receiver chain. See also 5G Media Streaming over eMBMS (3GPP Release 17) for the related VideoTech session.
Related: Public Warning Systems (Cell Broadcast Service public warning, layered on this same transmit and receive chain) · Media delivery over 5G Multicast Broadcast Services (the NR-native multicast and broadcast technology, a separate topic with a similar name) · Standards: Content Delivery Protocols (the FLUTE transport used to carry files over the broadcast bearer) · Standards: DVB-I Services over 5G (DVB-I service discovery, used to present broadcast services alongside broadband ones) (ETSI TS 103 720 V1.2.1 clause 5.15.1)
Documents
Explainers and reports of 5G-MAG on this subject.