if there is a co-bcch environment where two cells serving in same area with same BCCH, since BCCh is downlink then why the ul quality degraded. we know that ul and dl channel are spaced apart by 45mhz.
anyone please answer this query.
an ARFCN defines both an UL frequency and a DL frequency.
If you assign ARFCN=1 for a BCCH, it means the TRX email@example.comMHz and the MS firstname.lastname@example.orgMHz.
So both DL and UL should be interfered. And the UL will be more interfered because the MS are spread over a large area, resulting in multiple sources of interferences for the receiving side (the BTS)
On the other hand, in DL, the MS are usually more concentrated around their cell, and quite fare from the intereferer cell.