Generally, most call drops in the initial phase of network construction are caused by incorrect or missing configurations of neighboring cells. For intra-frequency neighboring cells on the LTE network, use the following methods to check whether the intra-frequency neighboring cells are missing:
Method 1: If the UE reaccesses the network immediately after the service drop, and the PCI reaccessed by the UE is different from the PCI at the time of the service drop, the neighboring cell may be incorrectly configured or missing. In this case, you can locate the latest intra-frequency measurement control message from the time when the service drop occurs, check the neighboring cell list in the measurement control message.
Method 2: On the network side, check whether the eNodeB processes the measurement report received from the UE and whether the X2 interface sends a HANDOVER_REQUEST message to the target cell. If the eNodeB does not process the measurement report received from the UE and the X2 interface does not send a HANDOVER_REQUEST message to the target cell, the neighboring cell may not be configured. (This method applies only to inter-eNodeB handovers. Intra-eNodeB handovers do not involve X2 interface interaction.)
Call drops caused by missing configuration of neighboring cells include call drops caused by missing configuration of inter-frequency neighboring cells and call drops caused by missing configuration of inter-RAT neighboring cells. The method of checking missing configurations of inter-frequency neighboring cells is similar to that of checking missing configurations of intra-frequency neighboring cells. The difference is that the UE does not measure or report inter-frequency neighboring cells when a call drop occurs. After the call drop occurs, the UE camps on the inter-frequency neighboring cell again. Missing configuration of inter-RAT neighboring cells indicates that a UE experiences a call drop on the LTE network. After the call drop occurs, the UE reselects an inter-RAT network to camp on. In addition, the signal quality of the inter-RAT network is good.
To locate incorrect or missing neighboring cells, use the Scanner function of the UE to scan frequencies and check whether there are cells with stronger signal strength that are not in the neighboring cell list.
If neighboring cells are incorrectly configured or missing, optimize the neighboring cells based on engineering parameters and electronic maps
