hi,
You should check all your rx path:
antenna
feeder connectors (collecting water ?)
jumpers / feeders (too much bended ?)
mains cables (TRDU – CDU)
all connectors
Then it is also possible that Rx path is OK, it is just that the Tx path is way better : are you using anything to boost the Tx of the BTS ?
(signal booster, repeater, tx diversity).
Check also that your mains cables and your feeders are not swapped.
A good approach is to analyse the radio measurements statistics (if available in nokia system ?) : check your path balance for each TRX of the whole BTS.
Cheers
pix