What is the difference between dB and dBm?

dBm is a unit of power level, measured in milli-watts in logarithm scale, that is,

dBm = 10 * log(W*1000)  where W is the power in Watts

dB is not a unit, it is the difference in dBm

Download Document on WCDMA Capacity Planning
Download WCDMA Radio Network Capacity Planning  
Download Document on RRC KPIs