I really wished I wouldn’t have to explain this here, but since you asked, I’ll give it a try:
First of all, I was just trying to point out the fact that the difference between synthesized and baseband hopping is not in whether the BCCH TRX hops or not.
In baseband hopping, each TRX transmits on a single frequency, whereas in synthesized hoppng, each TRX transmits on all the hopping frequencies. In baseband hopping, you can easily make the BCCH TRX hop because each time you need to transmit a burst on the BCCH, you just direct the burst to the appropriate TRX which is transmitting at the BCCH frequency.
The main problem with hopping on the BCCH TRX is the transmission of the dummy bursts( also known as c0 filling in ericsson), and in baseband hopping, this is easily done. For synthesizer hopping, it’s more complicated, and there are two methods used to achieve it.
1. An extra transmitter operating purely as a c0 filler is used. Anytime there are bursts to be transmitted on the BCCH freq, they are routed to this transmitter. If there are no bursts to be transmitted, then dummy bursts are transmitted instead. This method is in fact, a mixture of both baseband and synthesizer hopping
2. The timeslot handler of one of the transceivers is used only for the BCCH time slot (timeslot 0 of the BCCH frequency)and filling only. Thus, one FULL TRX will be used for ONLY the BCCH timeslot.
I hope this makes sense to you.
Let me add that it is not some extra “marvellous feature” as you said(I sense the sarcasm in there). It is a part of the frequency hopping feature. If you include the BCCH frequency in your hopping list, then one of the two features above is automatically used. If you have ALEX, you can read the frequency hopping document in there. It is well-explained.