Scheduler Log Reference

The MAC scheduler writes to the SCHED logger. Two independent loggers produce its output, both defined in logging/:

Result logger (scheduler_result_logger) — one Slot decisions line per scheduled slot, describing the grants written into the sched_result (PDCCH, PDSCH, PUSCH, PUCCH, SRS, ...).
Event logger (scheduler_event_logger) — one Processed slot events line per slot in which UE/cell events were processed (CRC, HARQ-ACK, BSR, UE creation, PRACH, ...).

Both are per-cell and tag every line with pci=<physical cell id>.

Verbosity

The output is controlled by the level of the SCHED logger:

Level	Result logger	Event logger
`info`	Summary line + compact one-line entries (`log_info`)	Only events with an info formatter: PRACH, RACH indication, ErrorIndication, cell creation
`debug`	Summary line + one detailed entry per line (`log_debug`)	All events, one detailed entry per line
below `info`	disabled	disabled

debug is a superset of info: it logs more entry types and more fields per entry.

`log_broadcast`

The result logger is constructed with a log_broadcast flag. When false, these broadcast/common allocations are omitted: SSB, SIB, CSI-RS, DL-PRS, PRACH occasions and SI-RNTI DL PDCCH. This is normally enabled for a single cell only, so recurring broadcast allocations do not flood the log across all cells.

Log line anatomy

2026-07-02T09:29:21.835770 [SCHED   ] [D] [     1.5] Slot decisions pci=0 t=0us (1 PDSCH, ...):
└─ timestamp                 └─ logger  │    │        └─ message
                                        │    └─ slot as <SFN>.<slot-in-frame>
                                        └─ level: [I]=info, [D]=debug

The [ SFN.slot] field is the transmit slot the decisions apply to. Event lines carry the slot in which the events were processed.

If an entry does not fit in the log buffer segment, the logger drops it and writes an error line: Scheduler result log entry exceeded segment size and was dropped or Scheduler event log entry exceeded segment size and was dropped.

Result logger — `Slot decisions`

Summary line

A slot is logged only if it carries something worth reporting. Empty slots are skipped.

info: a SIB (with log_broadcast), a RAR/MsgB, a UE DL grant, a PUSCH, a paging grant, or a failed allocation attempt.
debug: a broadcast allocation (with log_broadcast: SSB, SIB, CSI-RS, DL-PRS, PRACH), a non-SI-RNTI DL PDCCH, a UL PDCCH, a paging grant, a RAR/MsgB, a UE DL grant, a PUSCH, a PUCCH, an SRS, or a failed allocation attempt.

info:

Slot decisions pci=0 t=0us (1 PDSCH, 1 PUSCH, 1 PUCCH): <entries...>

debug (adds attempted-but-failed allocation counters):

Slot decisions pci=1 t=0us (1 PDSCH, 0 PUSCHs, 0 PUCCHs, 0 attempted PDCCHs, 0 attempted UCIs):
- <entry>
- <entry>

Field	Meaning
`t=<n>us`	Scheduler decision latency for this slot, microseconds
`N PDSCH`	Number of PDSCH grants (UE grants + RAR/MsgB + paging, + SIBs when `log_broadcast`)
`N PUSCH`	Number of PUSCH grants
`N PUCCH`	Number of PUCCH grants
`N attempted PDCCH`	Failed DL+UL PDCCH allocation attempts (`debug` only)
`N attempted UCI`	Failed UCI allocation attempts (`debug` only)

At info level the entries follow the summary on the same line, comma-separated. At debug level each entry is on its own line prefixed with a - and a space.

info-level entries (compact, comma-separated)

Prefix	Format
`SIB1` / `SI-<n>` / `SI-?`	`SIB1: rb=<prbs> tbs=<bytes>`. `SI-?` when the SI message index is unknown.
`RAR` / `MsgB`	`RAR: ra-rnti=<rnti> rb=<prbs> tbs=<bytes>`. A 2-step grant prints `MsgB: msgb-rnti=<rnti> ...`.
`DL`	`DL: ue=<idx> c-rnti=<rnti> h_id=<harq> ss_id=<ss> rb=<prbs> k1=<k1> cw[0]: newtx=<true/false> rv=<rv> tbs=<bytes>`, then `cw[1]: newtx= rv= tbs=` with a second codeword. On new data appends `ri=<layers> dl_bo=<buffer-occupancy>`. When part of a Rel-16 PDSCH repetition bundle appends `reps=<n> reps_remaining=<n>`.
`UL`	`UL: ue=<idx> rnti=<rnti> h_id=<harq> ss_id=<ss> rb=<prbs> newtx=<true/false> rv=<rv> tbs=<bytes>`, then `k2=<k2>`, or `msg3_delay=<n>` for a Msg3 grant (invalid UE index, first tx).
`PG`	`PG: rb=<prbs> tbs=<bytes> ues: <cn\|ran>-pg-id=<0x..>, ...`

debug-level entries (one per line, `-` prefix)

Control channels:

- DL PDCCH: rnti=0x4601 type=c-rnti cs_id=1 ss_id=2 format=1_1 cce=8 al=2 dci: h_id=0 ndi=1 rv=0 mcs=3 res_ind=0 tdra_idx=3 tpc=1 dai=0 vrb_prb_map_used=no ant=0
- DL PDCCH: rnti=0xfffe type=p-rnti cs_id=0 ss_id=1 format=1_0 cce=0 al=4 dci: paging_ind=yes short_msg_ind=no tdra_idx=0
- UL PDCCH: rnti=0x4601 type=c-rnti cs_id=1 ss_id=2 format=0_1 cce=10 al=2 dci: h_id=0 ndi=1 rv=0 mcs=9 tpc=1 dai=0 mimo=1 ant=2

Field	Meaning
`type`	RNTI type (`c-rnti`, `tc-rnti`, `si-rnti`, ...)
`cs_id` / `ss_id`	CORESET id / SearchSpace id
`format`	DCI format (`1_0`, `1_1`, `0_0`, `0_1`)
`cce` / `al`	Starting CCE index / aggregation level (number of CCEs)
`dci: ...`	Decoded DCI fields. The content depends on the RNTI type and the DCI format. See below.

The dci: fields:

DL C-RNTI and TC-RNTI: h_id HARQ process, ndi, rv, mcs, res_ind (PUCCH resource indicator), tdra_idx (PDSCH time-domain-resource-allocation row index). Optional tpc (not for TC-RNTI). Format 1_1 adds dai (when present), vrb_prb_map_used and ant (antenna ports).
DL P-RNTI: paging_ind=yes|no short_msg_ind=yes|no. Then tdra_idx when the DCI schedules a paging PDSCH, and short_msg=0x.. (sysInfoMod=yes|no etwsCmas=yes|no) when the DCI carries a short message.
DL SI-RNTI and RA-RNTI: no dci: fields.
UL: h_id, ndi, rv, mcs, tpc. Format 0_1 adds dai, mimo (layers), ant and csi_req. UL DCIs do not print tdra_idx.

DL shared channel:

- SSB: ssbIdx=0 crbs=[5..26) symb=[2..6)
- CSI-RS: type=nzp crbs=[0..52) row=1 freq=0010 symb0=4 cdm_type=no_CDM freq_density=three scramb_id=1
- PRS: crbs=[0..52) symb=[2..14) n_id=0 comb_size=2 comb_offset=0
- SIB1 PDSCH: rb=[0..4) symb=[2..14) tbs=120 mcs=5 rv=0
- SI-1 PDSCH: rb=[0..4) symb=[2..14) tbs=120 mcs=5 rv=0
- RAR PDSCH: ra-rnti=0x2 rb=[0..8) symb=[1..14) tbs=32 mcs=0 rv=0 grants (1): tc-rnti=0x4601: rapid=5 ta=12 time_res=0
- UE PDSCH: ue=0 c-rnti=0x4601 h_id=0 ss_id=2 rb=[0..25) symb=[1..14) cw[0]: tbs=309 mcs=9 rv=0 nrtx=0 k1=4 ri=1 <pmi> dl_bo=1024 olla=0.03 grants: lcid=1: size=53, lcid=4: size=256
- PCCH: rb=[0..4) symb=[2..14) tbs=40 mcs=5 rv=0 ues: cn-pg-id=0x1234

SI-<n> PDSCH: SI-? PDSCH when the SI message index is unknown.
RAR PDSCH: a 2-step grant prints MsgB PDSCH: msgb-rnti=<rnti> .... Each 2-step grant appends result=successRAR|fallbackRAR.
UE PDSCH:
- nrtx = retransmission count.
- A second codeword appends cw[1]: tbs= mcs= rv=.
- ri/PMI printed only when precoding present.
- dl_bo (DL buffer occupancy) only on new data.
- olla (outer-loop link-adaptation offset) when set.
- reps/reps_remaining only when the grant is part of a Rel-16 PDSCH repetition bundle (reps = nominal bundle size, reps_remaining = repetitions still to be transmitted after this occasion, decrementing to 0 at the last one).
- Per-logical-channel grants: list when a TB is built, then a cw[1] grants: ... list for the second TB.

UL shared channel and control:

- UE PUSCH: ue=0 c-rnti=0x4601 h_id=0 ss_id=2 rb=[1..52) symb=[0..14) tbs=1121 rv=0 nrtx=0 nof_layers=1 cg=No olla=0 k2=4 uci: harq_bits=1 csi-1_bits=0 csi-2_present=No
- PUCCH: c-rnti=0x4601 format=0 prb=[0..1) symb=[12..14) uci: harq_bits=1 sr=0
- PUCCH: c-rnti=0x4601 format=1 prb=[0..1) prb2=50 symb=[0..14) cs=0 occ=0 uci: harq_bits=1 sr=0
- PUCCH: c-rnti=0x4601 format=2 prb=[1..2) symb=[12..14) uci: harq_bits=2 sr=0 csi-1_bits=4
- PUCCH: c-rnti=0x4601 format=4 prb=[2..3) symb=[0..14) occ=0/2 uci: harq_bits=2 sr=0 csi-1_bits=4
- SRS: c-rnti=0x4601 symb=[8..10) tx-comb=(n2 o=0 cs=0) c_srs=0 f_sh=0 seq_id=0 requests=[ch_mtx=yes pos=no]
- PRACH: pci=1 format=0 nof_occasions=1 nof_preambles=64

UE PUSCH: a leading t before c-rnti (tc-rnti=) marks a temporary-C-RNTI (Msg3) grant; cg=Yes marks a configured grant; olla when set; k2 is replaced by msg3_delay for the initial Msg3. uci: block present when UCI is multiplexed on PUSCH.
PUCCH: prb2 shown when frequency hopping. Format-specific fields:
- F0: no extra fields.
- F1: cs, occ.
- F2, F3: csi-1_bits.
- F4: occ=<idx>/<len>, csi-1_bits.

Interval notation

rb, symb, crbs are printed as half-open intervals [start..stop) — e.g. rb=[1..52) is 51 PRBs starting at PRB 1; symb=[0..14) is all 14 OFDM symbols.

Event logger — `Processed slot events`

Emitted once per slot in which one or more UE/cell events were processed.

info (comma-separated, only events with an info formatter):

Processed slot events pci=1: prach(ra-rnti=0x2 preamble=5 ssb=0 tc-rnti=0x4601), RACH Ind slot_rx=100.3, ErrorIndication slot=100.5

debug (one event per line):

Processed slot events pci=1:
- UE creation: ue=0 rnti=0x4601
- CRC: ue=0 rnti=0x4601 rx_slot=401.9 h_id=0 crc=ok sinr=100dB
- HARQ-ACK: ue=0 rnti=0x4601 slot_rx=401.5 h_id=0 ack=1 tbs=720
- BSR: ue=0 rnti=0x4601 type="Short BSR" report={2: 700}
- CSI: ue=0 rnti=0x4601: slot_rx=408.9 cqi=15
- RLC Buffer State: ue=0 lcid=4 pending_bytes=2400

Event types

Event	Levels	Notes
Cell creation	info + debug	Emitted once at logger construction. info: `Cell creation idx=<n>`; debug: `Cell creation: idx=<n>`
PRACH	info + debug	info: `prach(ra-rnti\|msgb-rnti=<rnti> preamble=<n> ssb=<n> tc-rnti=<rnti>)`; debug: `slot=<s> preamble=<n> ssb=<n> ra-rnti\|msgb-rnti=<rnti> temp_crnti=<rnti> ta_cmd=<n>`
RACH ind	info + debug	debug lists each preamble: `preamble`, `tc-rnti`, `freq_idx`, `start_symbol`, `TA=<x>s` (seconds)
ErrorIndication	info + debug	debug: `slot=<s>`, then `, PDCCH discarded`, `, PDSCH discarded` and `, PUSCH and PUCCH discarded` for each discarded channel
UE creation / reconfiguration / removal	debug	`ue=<idx> rnti=<rnti>`
UE dedicated config applied / UE deactivation	debug	`ue=<idx> rnti=<rnti>`
SR	debug	Scheduling request
CSI	debug	`cqi` / `ri` / `pmi` when present, else `invalid`
BSR	debug	`type` (Short/Long/...), `report={...}`. Long, long truncated or all-LCG reports list all 8 LCGs, comma-separated, with `-` for an LCG not reported. Other reports list `<lcg>: <bytes>` pairs
HARQ-ACK	debug	`ack` status (0/1/2); `tbs` shown on ACK
CRC	debug	`crc=ok\|ko\|dtx`, `sinr=<n>dB` or `sinr=N/A`
MAC CE	debug	`ue=<idx> lcid=<lcid>`
RLC Buffer State	debug	`ue=<idx> lcid=<lcid> pending_bytes=<n>`
PHR	debug	`ue=<idx> rnti=<rnti>`, then for each cell `scell=<id> ph=<n>dB` and optional `p_cmax=<n>dBm`
SRS	debug	optional `tpmi_info=[...]`
Slice Reconfig	debug	`cell=<idx>`

Common field glossary

Field	Meaning
`pci`	Physical cell id
`ue`	DU UE index (internal); `INVALID` denotes a temporary (pre-attach) context
`c-rnti` / `rnti`	UE C-RNTI
`tc-rnti`	Temporary C-RNTI (RA / Msg3 / Msg4)
`ra-rnti` / `msgb-rnti`	RA-RNTI (4-step) / MsgB-RNTI (2-step) derived from the PRACH occasion
`h_id`	HARQ process id
`ndi` / `rv`	New-data indicator / redundancy version
`newtx`	Whether the grant carries new data (`true`/`false`)
`mcs`	Modulation and coding scheme index
`tdra_idx`	PDSCH time-domain-resource-allocation row index signalled in the DL DCI
`tbs`	Transport block size, bytes
`rb`	Allocated PRBs, half-open interval
`symb`	Allocated OFDM symbols, half-open interval
`cw[0]` / `cw[1]`	First / second codeword of a PDSCH
`k1`	PDSCH-to-HARQ-ACK slot offset
`k2`	PDCCH/DCI-to-PUSCH slot offset
`nrtx`	HARQ retransmission count
`reps`	Nominal number of occasions in a Rel-16 PDSCH repetition bundle (1 = no repetition)
`reps_remaining`	Occasions of the bundle still to be transmitted after this one, counting only committed occasions
`dl_bo`	DL buffer occupancy (pending bytes)
`olla`	Outer-loop link-adaptation MCS offset
`ss_id` / `cs_id`	SearchSpace id / CORESET id

Verbosity​

log_broadcast​

Log line anatomy​

Result logger — Slot decisions​

Summary line​

info-level entries (compact, comma-separated)​

debug-level entries (one per line, - prefix)​

Interval notation​

Event logger — Processed slot events​

Event types​

Common field glossary​