L9121: DOWN_TOTAL_GPRS_TBF_EXIST_PERIOD
The downlink GPRS TBF of a cell is scanned per second. If any downlink TBF is operating in the data transmission state, it is regarded that the cell is in the data transmission state. If there is no established TBF, or the established TBFs are operating in downlink delayed release period, it is regarded that the cell is in the idle state. In a granularity period, the duration of scanned downlink GPRS TBFs in the data transmission state in a cell can be accumulated. That is, Total Duration of Downlink GPRS TBFs (s).
s.
In a granularity period, the BSC scans the downlink GPRS TBFs of a cell per second. If the downlink GPRS TBFs of a cell are in the data transmission state, the counter is incremented by one.
This is an original counter without involving any formula.