Fix Delta MCS mode, reimplement UL power control
This change set fixes the "delta-MCS" mode, and reimplements the UL power
control loops at gNB, i.e., for PUSCH and PUCCH. It further adds new T traces
to log PUSCH/PUCCH power infrmation, and cleans up code.
The "delta-MCS" mode in OAI refers to configuring a UE with deltaMCS in the
PUSCH-PowerControl IE (see TS 38.331). In this mode, the UE adjusts the PUSCH
power for transmissions to take into account for MCS (see TS 38.213 Sec. 7.1).
In other words, the target SNR can be set to a somewhat low value, and the UE
will still use the right power for UL transmissions. Note that the spec only
foresees this adjustment of UL power when using one layer. In contrast, in the
"normal" mode, the gNB sends TPC commands to keep a UE at a fixed target SNR
(default: 20dB), regardless of the MCS or number of layers. Future work is
planned to completely remove this fixed target SNR, which is not done in this
MR yet.
Further, there is a new power control loop implementation. Prior to this MR, on
each UL transmissions, the gNB uses the SNR to decide about TPC sent to a UE in
the next transmissions. The new implementation relies on averaging the SNR, and
a "TPC in flight" average to account for the slow reaction of the average SNR.
The sum of both quantities is the current SNR that is used by the UE. See the
commit messages or documentation for more information.
Further cleanup to group data (e.g., power control configuration, refactoring of
code to save space, ...) is done. Two new T traces GNB_MAC_PUSCH_POWER_CONTROL
and GNB_MAC_PUCCH_POWER_CONTROL are added; documentation exists to explain how
to graphically plot corresponding graphs.
Jaroslava Fiedlerova
4472b9d82a