Let us take a cell with 4 TRX.
TRX-1 BCCH so lets forget it.
TRX-2
HSN-2
MAL= f1 f2 f3 f4 f5 f6 f7 f8 f9 f10 f11 f12 f13 f14.
MAIO=2
TRX-3
HSN-2
MAL= f1 f2 f3 f4 f5 f6 f7 f8 f9 f10 f11 f12 f13 f14.
MAIO=4
TRX-4
HSN-2
MAL= f1 f2 f3 f4 f5 f6 f7 f8 f9 f10 f11 f12 f13 f14.
MAIO=6
All the TRX (from 2 to 4) are IDLE at a time (say).
A MS1 gets a TCH on TRX2. In RF/SFH case the TRX2 will start the hopping from f3 and will follow the HSN2 pattern. If in-between this another MS2 is allotted a TCH on TRX2 then it WILL NOT start hopping from f3, It will follow the MS1…the frequency the MS1 has transmitted in the last TDMA frame or the frequency MS1 is going to transmit on in the coming TDMA. After that HSN2 pattern will be continued.
At the same time if an MS3 is allotted a TCH on TRX3 then it will start at f5 (as MAIO=4) and will follow the HSN2 over MAL.
But even the use of MAIO doesn’t guarantee the exclusion of interference.
Take a case with reference to above.
MS1 AND MS3 request comes to network at such a time that there is a difference of two TDMA frames between them.
So, when MS1 was at f5 the MS3 starts from f5. As the HSN are same for both the TRX’s the both MS’s ie MS1 and MS3 will now follow the same frequencies during the whole period for which they remains in the dedicated mode.
Hence I am of the opinion that it is not the MAIO, which is criticle, but it is the HSN.
Unfortunately what i have seen is that HSN is kept same in RF hopping by the RF planners even though there is no scarcity of it.
Regards
MKT