# Call Model and Test-Verification Methods for PS-LTE Core Equipment
## 4 Measurement of Wireless Coverage and Quality
### Testing Mobile Base Stations
#### 4.3.2 Test Results of the Network Performance of Vehicle-Type Mobile Base Stations  
The RAN-sharing test in the downtown area is conducted between fixed base stations \(\leftrightarrow\) mobile base stations, commercial network base stations \(\leftrightarrow\) mobile base stations, and maritime network base stations \(\leftrightarrow\) mobile base stations. Figure 12 shows that when the PS-LTE terminal is set to the RAN-sharing mode in the P2 area and moves among the other communication networks, the signal level of the serving cell decreases while the terminal is connected to the maritime networks (Band28, PCI 466); therefore, it is handed over to the commercial networks (Band3, PCI 469). Because handover occurs when the signal level of the serving cell is in the range of \(-117\) dBm recommended by DSCNs, it satisfies the design value. The P1 section is a densely populated area with a large floating population due to Annok Beach (Gangneung Cafe Street), which is a target coverage area for DSCNs. However, although it is located at a close distance of 1.7 km from the Songjeong-dong base station (PS-LTE) under the coverage shadow area of the DSCNs and call fails/drops occurs frequently, the signal level is very low (RSRP \(-100\) to \(-120\) dBm); thus, optimization is required to secure coverage.  
Figure 11: Test environment for mobile base stations.  
Data transmission speed is measured in the downtown area where the PS-LTE mobile, fixed, marine network, and commercial network base stations are installed, centering on the KT Gangneung branch. For the download speed in Figure 13, although RSRP and signal-to-interference ratio (SINR) are good for the coverage section of the vehicle-type mobile base station (PCI 500) in the P1 section, the download speed is 0-1 Mbps, owing to the limit of the satellite backhaul bandwidth (2 Mbps). The download speed in the P2 section is 2-4 Mbps, owing to the SINR degradation caused by wave interference between PS-LTE and LTE-M. Although the P3 section is the coverage shadow section of PS-LTE and LTE-M (RSRP, \(-104\) dBm and SINR, \(-1\) dB), the download speed is measured at 6 Mbps, which is higher than in the area of the wave interference. Evidently, the resolution of the wave interference between PS-LTE and LTE-M should be considered a priority.  
The summary and analysis of the test results of the coverage in disaster safety communication network and mobile base station are as follows:  
* The target of service area for disaster safety communication network is densely populated areas including national infrastructure and roads with two or more lanes. However, as a result of the coverage test, there are many areas share with commercial network due to the shaded sections; hence, it is necessary to improve and optimize the coverage.
* As the area where the disaster safety communication network and LTE-R RAN Sharing are not applied is measured, the voice call quality of the disaster safety communication network service is very poor. Therefore, early interworking measures through consultation with involved organizations are required.
* When measuring disaster safety communication network and LTE-M RAN-sharing, because there are many cases where the Physical Resource Block is not allocated and data cannot be transmitted at the transmission rate (DL, UL) 0 Mbps, it is necessary to check the RAN-sharing parameter and the system.  
Figure 12: Analysis of RAN sharing items.  
Due to the coverage shadow section between the disaster safety communication network and LTE-M and the instability of RAN sharing, poor voice call quality, such as call drops and call fails, occurs; hence, optimization work is needed to improve the coverage between public networks.
* The overall voice call quality in the boundary area between different types is good. However, because of poor coverage in some areas and quality deterioration due to the base station, output abnormality occurs; hence, equipment inspection and coverage optimization are required.