Recently, as non-terrestrial networks (NTN) are recognized as new access networks, the communication paradigm is changing. The 3rd generation partnership project (3GPP) started standardizing new radio (NR)-based NTN in release 15. NTN’s wide coverage expand the network system of next-generation mobile communication. In particular, low earth orbit (LEO) satellites have a good deal of potential commercially, with costs drastically reduced due to reusable rockets.
However, LEO-based NTN has a mobility issue different from that of terrestrial network (TN). The high mobility of the LEO shortens the time the terminal stays for each cell. As a result, frequent handover occurs, and the performance of handover becomes a more important issue. In addition, LEO, which operates at a high altitude, makes the RSS variation of a cell small. It is difficult to expect high performance when applying TN’s RSS-based handover method. 3GPP recognizes this issues and discusses a handover method using location information. Several method of measurement report triggering have been proposed for the handover method using location information, but the specific method is unclear. This is because there is a lack of performance analysis data for each method.
In this dissertation, the LEO-based NTN environment is implemented on a cellular basis and the performance of handover method using location information is analyzed. Similar to the A3 event, the location-based event triggers the measurement report when a center of neighbor cell becomes closer than that of serving cell. The handover process is divided into states to compare the performance of RSRP-based events and location-based events.
The location-based event has higher accuracy than signal strength, which has randomness by fading. In an environment of the NTN with little change in signal intensity, the location-based event is advantageous because the influence of fading acts larger than that of the TN. As a result of simulation, location-based event show higher performance in terms of RLF per second, handover failure rate, handover delay, interruption time and radio resource control re-establishment success rate.
