L9553: CELL_LLC_TX_DOWN_GPRS_BKGND_LLC_PDU_TRANS_DURATION
This measurement provides the transmission duration of all downlink GPRS background services in a cell in a granularity period.
ms.
Each time the transmission of the background service is complete on the downlink GPRS TBF, the transmission duration is taken as the transmission duration of the downlink GPRS TBF background service. In a granularity period, the sum of the transmission duration of all background services on the downlink GPRS TBFs is taken as the total transmission duration of downlink GPRS background service.
This is an original counter without involving any formula.