Hmmm……well, suppose there are 2 TRXs under a BTS, then, for obvious reasons BCCH will be on, say TRX0, and TRX1 will hv all the remaining TCHs. So in this case TRX0 is a BCCH TRX while TRX1 is a TCH TRX. But it should not matter though, except for some extraordinary behaviour!!
Thanx adcguy….But in a frame, we have 8 timeslots,you are right that 0 is BCH and rest are for TCH.But sometime BCH and TCH ARFCN are same,I have still the same question…BCH and TCH TRX are seperate antennas?
Awacs, remember that GSM is a TDM access method, so on the BCCH ARFCN, there will be 8 TS which are TDMed, and one of them is BCCH, and the remainging 7 is the TCH. All this is very abstract and its a bit difficult to understand. U can google GSM TDM frames and get some pictorial info so that u will understand it better(difficult to explain in words).
So if you go by this logic, 2 TRXs will have 2 ARFCNs, and they use a duplexer or something and radiate using the same antenna.
BCCH TRX is just a nickname used to describe the first TRX of a cell, which carries the BCCH on the first timeslot.
This TRX is a bit special because it always emit (even when there’s no call on it) during all timeslots, and there is no power control : it emits at full power all the time.