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Reply To: Two BCCH in one Sector…..?

#69229
pix
Guest

hi,

ok, so if it is specifically stated “BCCH” in Nemo, it is indeed the BCCH frequency of the current serving cell, and not its “TCH” frequency. the TCH freq (or TCH ARFCN) is probably shown somewhere else in the interface.

A standard MS may or may not listen to the BCCH of its serving cell. There is no need to listen to it, as all the required signalling info are transmitted over the SACCH (which is located on the current TCH).
However some operator can set parameters so that MS are forced to measure the BCCH freq, as if it were a BCCH neighbour (a little tricky AND not needed, as I said above).
The NEMO MS might have specific software, and therefore might listen continuously to the BCCH freq, in order to provide BCCH RXLEV along with the TCH RXLEV.

In your case, if the BCCH freq is different than the one you expect, then I suspect that you are not in the cell you think you are. During call setup, the MS goes from IDLE to DEDICATED MODE. However, if the serving cell is congested, the MS is handover immediately to a neighbour cell, which becomes the new serving cell. The bcch is therefore different. This HO during Call Setup is called “DIRECTED RETRY”. The MS is on SDCCH of CELL A and if cell A is congested, it is HO on a TCH of CELL B. Directed Retry is a HO from SDCCH A to TCH B.

Regards
pix