6.2MHz = 31 ARFCN, correct ?
3 sectors per sites
1 TRX “bcch” per cell
now, let’s assume :
freq reuse = 12 for BCCH –> 12 freq. are reserved for bcch only.
1 guard band channel
there are 31 – 12 – 1 = 18 ARFCN left for TCH
assuming a freq reuse of 9 for TCH (quite aggressive), it means you can put 2 additional “tch” TRX per cell.
So altogether : 3 TRX per cell max.
this is without hopping.
activating BBH will give you little bit more room to place your frequency, so once in a while you can put more than 3 trx in a cell.
with SFH :
18 ARFCN for tch trx
assuming a 1×1 reuse and a max radio load of 12%, it gives you a max number of trx per cell of 2.16.
–> an average of 3 trx / cell (1 bcch + 2 tch), and once every 6 cells, you can move up to 4 trx.
The maio is useful only in SFH, and it’s easy to plan. Just avoid identical or adjacent MAIO between TRX within the same BTS. And don’t forget to use the same HSN within the cells of the same BTS. And different HSN between different BTS.