it could be useful to say that you are talking about 2G 🙂
In 2G it is simple : more traffic = more timeslots used = more frequency usage = more interference = worse BER = Dropped calls.
To reduce interference due to load:
1/ first look at the ratio of HO QUALITY UL and HO QUALITY UL. Which one is worst : DL or UL ?
– reduce average power by reducing power control thresholds (for TCH)
– increase half rate usage (to reduce timeslot usage)
– GPRS power control works only in UL (Alpha & Gamma parameters). You can try Gamma = 32 and alpha = 0.8 (or “80”), which will have a little more effect than your settings.
There are other features to reduce interference in a network, but they require much more work:
– new frequency planning or new hopping strategy
– synchronized network