I have an application that is attempting to use multi-cell positioning based on the results of %NCELLMEAS.
The application is following the flow of the NCS positioning module (EXTENDED_LIGHT -> GCI_DEFAULT -> GCI_EXTENDED_LIGHT).
I am observing that most of the time, the GCI scans are failing to find any cells apart from the currently serving cell.
Differing from other similar questions here, the application is in RRC idle for all of the scan requests.
The initial scan results in multiple neighbor cells found and measured, so it is not an issue of no other towers being nearby (I am ~10km from a city center)
[00:17:12.676,361] <err> modem_monitor: State: Active [00:17:23.825,866] <err> modem_monitor: State: Idle ... Radio in RRC Idle [00:18:00.633,056] <wrn> task_network_scan: Cell Scan: Mode 2 GCI_Count 0 [00:18:01.463,928] <inf> task_network_scan: Serving Cell Valid: Yes, Neighbour Cells: 3 [00:18:01.463,958] <inf> task_network_scan: Serving ECI: 147045644 (-106 dBm) [00:18:01.463,958] <inf> task_network_scan: Neighbour: 337 (-118 dBm) [00:18:01.463,989] <inf> task_network_scan: Neighbour: 238 (-120 dBm) [00:18:01.463,989] <inf> task_network_scan: Neighbour: 70 (-129 dBm) [00:18:01.464,141] <wrn> task_network_scan: Cell Scan: Mode 4 GCI_count 7 [00:18:01.836,669] <inf> task_network_scan: Global Cells: 1 [00:18:01.836,669] <inf> task_network_scan: Global ECI: 147045644 (-107 dBm) [00:18:01.836,791] <wrn> task_network_scan: Cell Scan: Mode 5 GCI_count 7 [00:18:09.843,841] <inf> task_network_scan: Global Cells: 1 [00:18:09.843,872] <inf> task_network_scan: Global ECI: 147045644 (-107 dBm) ... Uplink here, transition to RRC Active [00:18:12.688,781] <err> modem_monitor: State: Active [00:18:25.178,192] <err> modem_monitor: State: Idle
While the lack of GCI cells is not a huge issue here with the multiple neighbors reported, the application also operates in regions where the network does not provide neighbor information, so the performance of the GCI scanning is critical.
Occasionally the `GCI_DEFAULT` search does find a second cell, but I am yet to see `GCI_EXTENDED_LIGHT` return useful information, despite searching for ~7.5 seconds each run.
I feel like I must be doing something wrong, but I have no idea what it could be.
Model: nRF9151-LACA
Firmware: mfw_nrf91x1_2.0.3
Mode: LTE-M + GNSS (Prefer: No preference)