AR3555A: CELL_CHAN_BUSY_NUM_TCH_RATE
This measurement provides the rate of seized TCHs to all the TCHs in a granularity period. This measurement indicates the TCH seizure rate.
%.
The BSC samples the channel states every five seconds, and the number of seized TCHs and available TCHs is measured when the timer expires. The measured value is the rate of TCHs in busy state.
This is an original counter without involving any formula.