the higher the “trx pref mark”, the higher the priority of the TRX when it comes to TCH ALLOCATION.
TRX 1 – trx pref mark = 4
TRX 2 – trx pref mark = 2
TRX 1 will have higher priority than TRX 2 for getting TCH allocated on its timeslots.
Once all timeslots of TRX 1 are busy, then only the BSC will allocate calls on the TRX 2.
Therefore TRX 1 will be very busy, while TRX 2 may take only little traffic during the day.
Trx Pref Mark = 0 means the TRX can carry PDCH ((e)GPRS traffic) and voice (TCH).
If Trx Pref Mark > 0 then the TRX can only carry voice (TCH).