The idea is to force the MS to measure extra frequencies, and send YOU the results, in the form of statistics.
Each MS acts as a drivetest device. The result you get is the difference of rxlev between cell1 and cell2.
What is not clear is whether you can decide what is the frequency you can measure there. In E/ and ALU system, you can force the MS to measure the whole BCCH band, which provide you a very clear picture of cells coverages.
In ZTE, it sounds like it has to be the bcch of the colocated cell only ? Maybe I’m mistaken.