RAN1, the 3GPP working group that designs the physical layer of the radio interface, met in Jeju, South Korea, from 12 to 16 October 2026. Most of the week went to the Rel-20 study of the 6G radio interface (6GR), whose results are collected in TR 38.760-1. A study is the stage in which options are assessed and narrowed before binding specifications are written. Our preview of the October meetings asked whether RAN1 would fix the basic structure of 6G cell search this month. This article records what RAN1 actually agreed, based on the draft meeting report and the end-of-meeting chair notes.

The short version: RAN1 made many small, firm decisions and moved most of the big ones to its next meeting. The 6G synchronization block now has a fixed slot structure, four-step random access is the baseline, the downlink control channel stays single-port and QPSK-only, and the uplink will not get a special low-PAPR scheme for 16QAM. But the number of symbols in the synchronization block, its default period, and whether one transport block may span a 400 MHz carrier are all deferred to RAN1#127 in Calgary (16–20 November 2026).

A sense of scale: the draft report records 364 agreements, conclusions and working assumptions, 229 of them in the 6GR study. Many of them are study scaffolding rather than design choices: evaluation templates, simulation assumptions and lists of options "for further study" (FFS). The study report TR 38.760-1 entered the meeting as v0.6.0; the rapporteur's v0.7.0 with this meeting's results is allocated as R1-2608799 and was not yet on the 3GPP server on 22 October.

Cell search: the structure is set, the numbers are not

A phone that switches on looks for the Synchronization Signal Block (SSB): a short burst carrying the Primary and Secondary Synchronization Signals (PSS, SSS) and the broadcast channel. Its size and how often it repeats drive both how quickly a phone finds a cell and how long a base station can stay silent between bursts, which is the core of 6G network energy saving.

Agreed in Jeju:

  • Each slot that contains SSBs has two candidate SSB time locations.
  • One 6GR SSB spans X OFDM symbols within a slot, with X still to be down-selected from 4, 5 or 6. With four symbols, PSS and SSS get one symbol each; with five or six, the PSS gets two symbols.
  • The maximum number of SSB beams per period is 4 or 8 below 3 GHz, 8 below 6 GHz and 16 around 7 GHz.
  • The timing-advance offset is configurable (for terrestrial networks in FR1: 0, 25600 or 39936 basic time units).

Not agreed: the default SSB period for initial cell search. The agreement lists five options for down-selection: 160 ms with up to four repetitions inside one period, two 80 ms variants, two 40 ms variants, and 20 ms with combining over four periods. NR uses 20 ms. The longer the period, the longer the base station can sleep, and the more the phone has to combine repetitions to reach the same coverage. RAN4 is to define the performance requirements behind whichever option is chosen. So the answer to our preview's question is no: the October target for the basic time structure was only partly met.

Random access and initial access

  • Four-step random access is the baseline procedure for 6GR. Two-step random access, RACH-less access for phones that already have uplink timing, and a dedicated one-step procedure remain under study as additional procedures that will need a justification. RAN1 answered RAN2's questions on 6G random access in an approved liaison (R1-2608788), noting that its answers rest on the 5G two-step design, which "may or may not be applicable for 6GR".
  • For single-carrier operation, the reference point of the carrier's resource grid (CRB0) is not signalled in the master information block but in SIB1, the first system information message.
  • The bandwidth of the control region used to receive SIB1 is signalled in the master information block from a predefined set that does not depend on the phone's bandwidth capability.
  • Multi-carrier initial access: RAN1 concluded that letting a phone send its first uplink messages (Msg1, Msg3) on a lower-frequency uplink carrier while it keeps receiving on a mid- or high-band carrier can improve uplink coverage for phones that hear the cell well but cannot reach it. Which carrier combinations will actually be supported is still being studied.

Waveform, coding and modulation

The 6G uplink is studied with two waveforms, CP-OFDM and DFT-spread OFDM. The open question was how far to go in reducing the peak-to-average power ratio (PAPR), which limits how much power a phone can push out.

  • A dedicated low-PAPR enhancement for uplink 16QAM is not pursued. Evaluations showed net losses for plain spectrum shaping with 16QAM compared with a scheme without shaping.
  • For low-PAPR enhancement with steep transmit filters: the same filter applies to reference and data symbols, using knowledge of the filter in the receiver is an implementation choice, and RAN1 will not define filter coefficients. RAN4 decides how to characterise the filters, for example through a spectrum mask. The evaluations put the gain from a receiver that knows the filter at roughly 0–0.5 dB without spectrum extension and 0–1.3 dB with it.
  • Uplink 1024QAM: the 5G downlink 1024QAM MCS table is the reference for the uplink table at least for CP-OFDM, and an MCS table for 1024QAM with DFT-spread OFDM will be studied.
  • Polar codes for payloads beyond the 5G range: uplink control information larger than 1,706 bits will use at most six segments (exact number FFS); for downlink control information larger than 140 bits, the maximum mother code length (512 or 1024) is to be chosen at RAN1#127. Whether such large payloads are needed at all must still be confirmed elsewhere.
  • Whether 3 to 11 bits of uplink control information still use the 5G Reed-Muller code, or a new scheme, is also to be concluded at RAN1#127.

Control and data channels

  • Downlink control channel (PDCCH): single-port DMRS is supported; there is no consensus for multi-port DMRS, for orthogonal multi-user MIMO, for precoding the UE has to know about, or for any modulation other than QPSK. Precoding granularity of at least one REG bundle is supported, and the 5G block interleaver is the baseline for interleaved mapping.
  • Downlink data channel (PDSCH): the question whether one transport block may span up to 400 MHz, or a 200–400 MHz allocation is split into two transport blocks, was meant to be settled in Jeju. It was moved to RAN1#127, with complexity, power consumption and performance named as decision criteria. This is the physical-layer side of the 200–400 MHz carrier question our preview listed for RAN4. The codeword-to-layer mapping is also to be chosen at RAN1#127.
  • PDSCH reference signals: a first set of time-domain DMRS patterns is supported for single-slot PDSCH, and phase-tracking reference signals are sent from one port at least for single-TRP transmission.
  • Uplink data channel (PUSCH): a single mapping type, a start symbol from 0 to 13 and length from 1 to 14 symbols (one-symbol PUSCH at least for CP-OFDM), repetition across slots with the same start and length, and contiguous resource allocation with one-RB granularity.
  • Activating semi-persistent downlink scheduling (SPS-PDSCH) by RRC signalling alone is not supported in 6GR.
  • Downlink HARQ acknowledgements are carried in physical-layer signalling, with a design that allows the trigger for acknowledgement feedback to be decoupled from the downlink assignment.
  • A phone supporting inter-band carrier aggregation can send PUSCH and PUCCH simultaneously on different carriers. RAN1 noted RAN4's decision that 6G replaces the combined power class of 5G uplink carrier aggregation with a per-band power class.

Channel state information and sounding

  • The 6GR CSI reference signal uses a PN sequence with QPSK modulation. Other sequences for special uses, such as sensing, are discussed separately.
  • Sounding reference signals: cyclic-shift port multiplexing for 2, 3, 4 and 8 ports and comb-based multiplexing for 3, 4 and 8 ports, both without time-domain multiplexing; SRS resources are grouped into resource sets, and one resource can belong to several sets.
  • Most CSI work, including codebooks for coherent joint transmission, explicit feedback and AI-based compression, is still at the stage of agreeing evaluation templates.

Wake-up signal and network energy saving

A wake-up signal (WUS) lets a phone stay in a low-power receiver mode until the network tells it to look for paging or data.

  • One WUS sequence occupies one OFDM symbol; the bandwidth is configurable but does not exceed 10 MHz.
  • In idle mode, a phone that receives a wake-up indication then monitors the paging control channel, and the WUS monitoring period equals the paging period.
  • Up to eight sequence candidates target one phone per WUS resource; the cell-wide maximum (32, 64, 128 or 256) is to be chosen at the next meeting.

Satellites and sensing

  • 6G non-terrestrial networks: phones with different GNSS modes (GNSS-based, GNSS-degraded and GNSS-free) can operate in the same cell, and the network gets a way to control which modes may access it. The pre-compensation solutions recommended in TR 38.742 are the starting point for the GNSS-less study.
  • Integrated sensing and communication (ISAC) remains in evaluation: RAN1 agreed metrics, overhead definitions and working assumptions for candidate sequences. In a liaison it states that CP-OFDM as defined for 6GR is the starting point for the sensing waveform study.

What happens next

RAN1#127 meets in Calgary from 16 to 20 November 2026, in the same week as SA2#178. Its list includes the SSB symbol count and default period, the 200–400 MHz transport-block question, codeword-to-layer mapping, the polar mother code for large control messages, Reed-Muller for small ones, and the cell-wide WUS candidate count. Email discussions on satellite link budgets run between the meetings. The RAN plenary meets in Boston on 7–10 December. The meeting report is a draft (v0.1.0) until RAN1 approves it.

Sources

RAN1#126-bis draft meeting report v0.1.0 and end-of-meeting chair notes (eom1), agenda items 10.2–10.8 (Rel-20 study of 6GR). Quoted decisions appear in both documents. The counts of agreements are our tally of the draft report. Rel-20 5G-Advanced work items handled at the same meeting (AI/ML for CSI, MIMO Phase 6, Ambient IoT Phase 2, GNSS-resilient NTN) are not covered here.