An optimized Doppler-based LTE measurement procedure for A4 handover triggering event in high speed train networks

Wireless Communication network is essential for railway sector as it improves the railway services as well as provides safety and reliability for its operation. Global System for Mobile Communications Railways (GSM-R) is widely used in railway systems. It is believed to have availability and reliability because of its commercial success. At the same time, GSM-R has a lot of shortcomings especially in high speed transmission. Therefore, the Long Term Evolution for Railway (LTE-R) is considered as the natural evolution for current (GSM-R) system. Very high speed trains suffer from many handovers between cells. One of the main targets of LTE-R is to provide fast and lossless handover between different cells. As a result, handover triggering decision is very critical in the design process of handover. Too late handover triggering is considered as one of the major problems that cause radio link failure. It occurs when the train is moving faster than the handover parameter settings. In this paper, an optimized Doppler-Based measurement handover procedure for High Speed Trains (HST) is proposed. The goal of this procedure is to accelerate the measurement procedure (shorten measurement time Tmeas) when the train is moving toward a target cell with a higher speed than designed. Hence, the probability of too late handover triggering will be reduced causing a subsequent reduction in radio link failure probability.