Hi Phaysal, firstly I am based in the UK.
You need to treat synchronisation in two ways, firstly a gradual degradtion in the synchronisation of the BTS clock, BTS clocks are designed to only allow small changes in clock freq over long periods of time. In Nokia BTS you have DAC words which describe the range of adjustment for the BTS clock and when they get to certain extreme ranges will generate alarms. The KPI’s will generally show a gradual degradation and is likely that you fix the issue and then realise the performance improvements.
Jitter however we have seen on SDH links with excessive pointer movements, which effect the BTS’s ability to utilise the PCM clock for timing. (All of our BTS’s are E1 fed, but higher bit rate circuits are used between the BTS and BSC)In this case KPI’s are difficult to quantify, depends on how often the changes are occurring.
Hope this helps?