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Reimplement (PUSCH) power control

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Introduce new data structures to track the average SNR and RSSI, and
that allow to dynamically modify the target SNR (per UE) as well as
continuously get TPC updates based on the average SNR. The target SNR is
per power control loop (which a future commit will extend to use for
PUCCH).

Concretely, it maintains an average of measured SNR and RSSI.  It also
updates "tpc_in_flight", which tracks TPC changes that don't show up in
the average yet. For instance, imagine that the target SNR of 15 changes
to 20. Three successive TPC commands need to be sent (+3, +1, +1), but
it will take time to show up in the average SNR. To account for this,
tpc_in_flight is updated by the TPCs sent, and an average will make it
go down back to zero at the same pace as the average SNR approaches the
target SNR.  The sum of average SNR and tpc_in_flight sums up to the
actual, current SNR, which approximates the target SNR.

The SNR is kept within -1<=targetSNR<=+2dB to avoid too many TPC
changes.

The current average SNR (sum of average SNR and tpc_in_flight) is used
to continuously get TPC updates, taking into account recent TPCs sent,
the difference to target SNR, and RSSI.

If there is DTX, tpc_in_flight is modified to artificially introduce TPC
commands which increase the currently used SNR of the UE. This is
temporary, as tpc_in_flight eventually will go back to zero. If the DTX
was due to sudden SNR drop (e.g., higher path loss), this will allow to
quickly adapt the UE's SNR to new conditions.

The periodical logs are extended to not only show the current SNR, but
also the difference from the target for better analysis.

Co-authored-by: Maxime Elkael <m.elkael@northeastern.edu>
This commit is contained in:
Robert Schmidt
2026-03-23 17:47:32 +01:00
co-authored by Maxime Elkael
parent ffae59427a
commit db0f6696f4
10 changed files with 189 additions and 61 deletions
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doc/MAC/mac-usage.md
+4 -5
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@@ -82,7 +82,7 @@ UE RNTI 2460 CU-UE-ID 2 in-sync PH 28 dB PCMAX 24 dBm, average RSRP -74 (8 meas)
UE 2460: CQI 15, RI 2, PMI (14,1)
UE 2460: UL-RI 2 TPMI 0
UE 2460: dlsch_rounds 32917/5113/1504/560, dlsch_errors 211, pucch0_DTX 1385, BLER 0.19557 MCS (1) 23 CCE fail 3
UE 2460: ulsch_rounds 3756/353/182/179, ulsch_errors 170, ulsch_DTX 285, BLER 0.33021 MCS (1) 27 (Qm 8 dB) NPRB 5 SNR 31.0 dB CCE fail 0
UE 2460: ulsch_rounds 3756/353/182/179, ulsch_errors 170, ulsch_DTX 285, BLER 0.33021 MCS (1) 27 (Qm 8 dB) NPRB 5 SNR 31.0 (-1.0) dB CCE fail 0
UE 2460: MAC: TX 1530943191 RX 194148 bytes
UE 2460: LCID 1: TX 651 RX 3031 bytes
UE 2460: LCID 2: TX 0 RX 0 bytes
@@ -162,10 +162,9 @@ The fourth and fifth line show HARQ-related information:
fluctuate a lot but when doing high throughput with iperf, it indicates the
number of PRBs that the UE is actually able to use with its power budget and
should be high.
* ULSCH `SNR`: the current SNR that the gNB receives the UE signal with. It
should be close to the target in the gNB configuration file,
`pusch_TargetSNRx10`, which should be around 10 times the value shown in the
log
* ULSCH `SNR`: the current SNR that the gNB receives the UE PUSCH signal with.
This value should be close to the target SNR; in paranthesis, the difference
to the target SNR.
* Both ULSCH/DLSCH `CCE fail`: lists the number of failed CCE attempts. If this
number gets high, it signifies that the scheduler tried to scheduled this UE,
but could not allocate the DCI.