closed loop uplink power control
OsmoPCU currently only implements open loop power control, where the uplink power is based on the signal loss in the downlink direction with the assumption that uplink loss equals downlink loss.
GPRS optionally specifies closed loop power control, which works more like what we know from circuit-switched GSM. To make things complicated, it can even be a combination of open loop and closed loop.
Whatever we do in this area is an optimization problem and we'd need a good test/simulation case in order to benchmark any changes in the implementation.