An optimized handover trigger scheme in LTE systems for high-speed railway

With the development of high-speed railway all over the world, the reliability and communication of bullet train depends on the wireless communication between train and Base Stations (BSs) along the railroad. Traditional handover scheme of Long Term Evolution (LTE) network is that `neighboring cell becomes better than an offset relative to the serving cell' during Time To Trigger (TTT), it avoids ping-pong between two cells effectively, but in high-speed railway, it would lead to radio link failure as it can't trigger handover. On the other hand, it would cause false trigger and alternate signaling frequently if just cutting down TTT. This paper includes a brief overview of traditional handover scheme, followed by an analysis of it in high-speed railway based on LTE systems. The analysis emphasizes the effects of velocity on handover. A scheme based on the train's position is proposed. The scheme adjusts TTT and entering and leaving condition of trigger handover at different positions. The simulation results show that the proposed scheme triggers handover more effectively as compared with traditional handover scheme, thus decreases outage probability and improves handover success probability.