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, broadcast/common allocations (SSB, SIB, CSI-RS, PRACH occasions, and SI-RNTI PDCCH) are omitted. 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.

Result logger — `Slot decisions`

Summary line

A slot is logged only if it carries something worth reporting: a UE DL/UL grant, RAR, paging, a non-SI-RNTI PDCCH, (with log_broadcast) a broadcast allocation, or any failed allocation attempt. Empty slots are skipped.

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): <entries...>

Field	Meaning
`t=<n>us`	Scheduler decision latency for this slot, microseconds
`N PDSCH`	Number of PDSCH grants (UE grants + RAR + 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 - .

info-level entries (compact, comma-separated)

Prefix	Format
`SIB1` / `SI-<n>`	`SIB1: rb=<prbs> tbs=<bytes>`
`RAR`	`RAR: ra-rnti=<rnti> rb=<prbs> tbs=<bytes>`
`DL`	`DL: ue=<idx> c-rnti=<rnti> h_id=<harq> ss_id=<ss> rb=<prbs> k1=<k1> newtx=<0/1> rv=<rv> tbs=<bytes>` — on new transmissions 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=<0/1> 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
- 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=0 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 — `h_id` HARQ process, `ndi`, `rv`, `mcs`. DL adds `res_ind` (PUCCH resource indicator), `tdra_idx` (PDSCH time-domain-resource-allocation row index; omitted for paging DCIs short message) and optional `tpc`/`dai`/`vrb_prb_map_used`. UL adds `tpc` and, for format 0_1, `dai`/`mimo` (layers)/`ant`/`csi_req`

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
- SIB1 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 rb=[0..25) symb=[1..14) 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

UE PDSCH: nrtx = retransmission count; 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. RAR result=successRAR|fallbackRAR appears for 2-step grants.

UL shared channel and control:

- UE PUSCH: ue=0 c-rnti=0x4601 h_id=0 rb=[1..52) symb=[0..14) tbs=1121 rv=0 nrtx=0 nof_layers=1 olla=0 k2=4 uci: harq_bits=1 csi-1_bits=0 csi-2_present=No
- PUCCH: c-rnti=0x4601 format=1 prb=[0..1) prb2=50 symb=[0..14) cs=0 occ=0 uci: harq_bits=1 sr=0
- 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 marks a temporary-C-RNTI (Msg3) grant; 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 — cs/occ (F1), occ=<idx>/<len> (F4); csi-1_bits shown for F2/F3/F4.

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

Processed slot events pci=1: prach(ra-rnti=0x2 preamble=5 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=true 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} pending_bytes=706
- 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
PRACH	info + debug	Detected preamble → RA-RNTI/MsgB-RNTI, `tc-rnti`; debug adds `preamble`, `temp_crnti`, `ta_cmd`
RACH ind	info + debug	debug lists each occasion: `preamble`, `tc-rnti`, `freq_idx`, `start_symbol`, `TA`
ErrorIndication	info + debug	debug lists which channels were discarded (PDCCH / PDSCH / PUSCH+PUCCH)
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/...), per-LCG `report={...}`, `pending_bytes`
HARQ-ACK	debug	`ack` status (0/1/2); `tbs` shown on ACK
CRC	debug	`crc=true/false`, `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	`ph=<n>dB`, 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`/`t`-prefix 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
`mcs`	Modulation and coding scheme index
`tdra_idx`	PDSCH/PUSCH time-domain-resource-allocation row index signalled in the DCI
`tbs`	Transport block size, bytes
`rb`	Allocated PRBs, half-open interval
`symb`	Allocated OFDM symbols, half-open interval
`k1`	PDSCH-to-HARQ-ACK slot offset
`k2`	PDCCH/DCI-to-PUSCH slot offset
`nrtx` / `nof_retxs`	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​