L
Admin
[Industry news, official editorial interpretation]
Two related items landed in the last few months, and together they matter for anyone designing or testing mid-band 5G radios.
1. The regulatory side
In July 2026 the US FCC adopted its Upper C-band Report and Order (FCC 26-46, adopted 22 July, released 24 July 2026). It makes 160 MHz at 3.98–4.14 GHz available for terrestrial flexible use through auction, with incumbent fixed-satellite operations being moved out of the band. On 8 October the Wireless Telecommunications Bureau opened the comment process for satellite operators' transition plans (initial plans due 5 November 2026).
Source: https://www.fcc.gov/document/fcc-adopts-plan-c-band-auction-july-2027-0
Order text: https://docs.fcc.gov/public/attachments/FCC-26-46A1.pdf
2. The standards side
At 3GPP RAN4#120-bis (Jeju, 12–16 October 2026) the radio-performance group, according to the public meeting summary, approved a work item to extend band n77 to cover the Upper C-band (3980–4140 MHz) through a new network-signalling (NS) value, with support for asymmetric deployments.
Meeting summary: https://whatthespec.net/3gpp/meeting/60732-3gppran4-120-bis
3. What it means in hardware terms
- n77 already spans 3.3–4.2 GHz, so most existing n77 PAs, LNAs and filters nominally cover 3.98–4.14 GHz. The work is mostly about emission requirements and signalling, not a new band from scratch.
- A new NS value usually means additional emission or A-MPR requirements that apply only when the network signals them. Expect UE vendors to revisit power back-off tables near the upper band edge.
- The upper edge, 4.14 GHz, sits only 60 MHz below 4.2 GHz, where radio altimeters (4.2–4.4 GHz) begin. 60 MHz at about 4.1 GHz is roughly 1.5 percent fractional spacing. That is steep for acoustic filters and even more so for ceramic or LTCC filters, so out-of-band emission into 4.2 GHz and above will be the critical test item.
- Path loss: from 3.5 GHz to 4.06 GHz (band centre) free-space loss rises by 20 log10(4.06/3.5) = 1.3 dB. That is small compared with building penetration loss differences, but it is not zero in a link budget.
- Test: spectrum emission mask and spurious measurements near 4.2 GHz will need analyser dynamic range and pre-filtering. Budget for a notch or high-pass in front of the analyser when you verify emissions under a high-power carrier.
4. What to watch next
RAN4#121 is scheduled for November 2026. The detailed requirements (emission limits tied to the NS value, any A-MPR) will come in change requests to TS 38.101-1 and TS 38.104, so watch those specs rather than press coverage.
Discussion: if you design n77 front-ends, does your current filter line-up already give enough rejection at 4.2 GHz with a carrier at 4.14 GHz? What margin do you plan for over temperature?
Note: this is a technical reading of public documents, not legal or regulatory advice. Corrections are welcome.
— rfforum 编辑部 / Editorial Team
Two related items landed in the last few months, and together they matter for anyone designing or testing mid-band 5G radios.
1. The regulatory side
In July 2026 the US FCC adopted its Upper C-band Report and Order (FCC 26-46, adopted 22 July, released 24 July 2026). It makes 160 MHz at 3.98–4.14 GHz available for terrestrial flexible use through auction, with incumbent fixed-satellite operations being moved out of the band. On 8 October the Wireless Telecommunications Bureau opened the comment process for satellite operators' transition plans (initial plans due 5 November 2026).
Source: https://www.fcc.gov/document/fcc-adopts-plan-c-band-auction-july-2027-0
Order text: https://docs.fcc.gov/public/attachments/FCC-26-46A1.pdf
2. The standards side
At 3GPP RAN4#120-bis (Jeju, 12–16 October 2026) the radio-performance group, according to the public meeting summary, approved a work item to extend band n77 to cover the Upper C-band (3980–4140 MHz) through a new network-signalling (NS) value, with support for asymmetric deployments.
Meeting summary: https://whatthespec.net/3gpp/meeting/60732-3gppran4-120-bis
3. What it means in hardware terms
- n77 already spans 3.3–4.2 GHz, so most existing n77 PAs, LNAs and filters nominally cover 3.98–4.14 GHz. The work is mostly about emission requirements and signalling, not a new band from scratch.
- A new NS value usually means additional emission or A-MPR requirements that apply only when the network signals them. Expect UE vendors to revisit power back-off tables near the upper band edge.
- The upper edge, 4.14 GHz, sits only 60 MHz below 4.2 GHz, where radio altimeters (4.2–4.4 GHz) begin. 60 MHz at about 4.1 GHz is roughly 1.5 percent fractional spacing. That is steep for acoustic filters and even more so for ceramic or LTCC filters, so out-of-band emission into 4.2 GHz and above will be the critical test item.
- Path loss: from 3.5 GHz to 4.06 GHz (band centre) free-space loss rises by 20 log10(4.06/3.5) = 1.3 dB. That is small compared with building penetration loss differences, but it is not zero in a link budget.
- Test: spectrum emission mask and spurious measurements near 4.2 GHz will need analyser dynamic range and pre-filtering. Budget for a notch or high-pass in front of the analyser when you verify emissions under a high-power carrier.
4. What to watch next
RAN4#121 is scheduled for November 2026. The detailed requirements (emission limits tied to the NS value, any A-MPR) will come in change requests to TS 38.101-1 and TS 38.104, so watch those specs rather than press coverage.
Discussion: if you design n77 front-ends, does your current filter line-up already give enough rejection at 4.2 GHz with a carrier at 4.14 GHz? What margin do you plan for over temperature?
Note: this is a technical reading of public documents, not legal or regulatory advice. Corrections are welcome.
— rfforum 编辑部 / Editorial Team