in SFH or in BBH, all TS during one TDMA frame will be emitted and transmitted with the same frequency. At the next TDMA frame, they’ll us the next frequency in the freq list.
For the BTS, it doesn’t matter which frequency it’ll have the chance to listen at a certain time. Over the hour, it is highly probable that it will have listen fairly to all the frequencies in the list.
In the end, you get the average rxlev of all the freq. in the list. If BBH/SFH is activated on all cells in the area, the measurement is significant : what matters in terms of interference at network level is the average noise generated by a mix of all frequencies.
well, that’s my opinion… what do you think ?