Measurement Counter
M320:CELL_CALL_DROPS_LOOP_FAIL_TIMEOUT_TCHH
Description
After the call is put through or the incoming BSC handover for the speech service is complete, within the BSC, the call processing module at the end initiating loopback start sends a loopback request message to the call processing module at the peer end during the BSC/BTS local loopback. In this case, the timer for waiting for the loopback acknowledgement message is started. Even after the timer is expired, a loopback request acknowledgement message is not received form the peer end because of various reasons. Thus, the loopback start fails (BSC/BTS loopback is not started yet at this time). The BSC regards it as a call drop and releases the call directly. The BSC loopback starts fails.
This measurement provides the number of call drops on TCHH due to loopback start failure (timer expired).
Unit
Integer number or integer.
Measurement Point
After the BSC receives the CONNECT ACK message from the MSC in the MS terminated call procedure, as shown in Figure 1(A1), or after the BSC receives the HANDOVER CMP message from the MS in the incoming BSC handover procedure for the speech service, as shown in Figure 2 (B1), the BSC selects the BSS local switch policy, determines the local switch start conditions, and performs local switch call detection. If all the local switch conditions are met, the BSC/BTS local loopback start procedure is started. Within the BSC, the call processing module initiating loopback start at one end sends a loopback request message to the call processing module at the peer end. At the same time, the timer for waiting for the loopback acknowledgement message is started. Even after the timer is expired, a loopback request acknowledgement message is not received form the peer end because of various reasons. The local loopback fails. Then, the BSC regards it as a call drop and releases the call directly. If the channel that carries the call during the call drop is a TCHH, this counter is measured.
Formula
This is an original counter without involving any formula.