I’m sure you will find a solution. But first of all, you must find where is the bottleneck 🙂
Sorry I forgot about previous analysis, but what is your conclusion ?
Do you think there is PS-congestion on Air, Abis, Ater PS, Gb interfaces ? (Which one? )
Or do you think the radio quality is poor ? (lot of RLC blocks retransmitted)
Please investigate your QoS stats…