If a specific cell has bad kpi’s it may have several problems and one of them is trx problem.
So u already found and going well this is the second step now.
What is quality, it is the bit error rate, how many percent of bits had errors or lost. two cases 1 is ul 1 is dl. so if u have stats for uplink and downlink there will be again 4 different scenarios
ul dl both bad quality
ul only bad quality
dl only bad quality
ul dl both good quality
and keep on thinking about this.
which u can fix with changing bcch which can be uplink interference and which is trx problem,
first thing check vswr