Adaptive Handover Algorithm for LTE-R System in High-Speed Railway Scenario

Yong Chen,Kaiyu Niu,Zhen Wang

doi:10.1109/access.2021.3073917

Yong Chen, Kaiyu Niu + Show 1 more

Open Access

https://doi.org/10.1109/access.2021.3073917

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Abstract

With the rapid development of high-speed railway, the LTE-R communication system has more requirements for the handover success rate. An adaptive handover algorithm based on random suppression in high-speed railway scenario is proposed. The algorithm establishes an elliptic function relationship between the hysteresis threshold and the train speed, so that the hysteresis threshold can be adjusted adaptively with the train speed, which lessens the challenge of high-speed train forward handover. At the same time, the normal distribution random number is introduced to suppress the reverse handover in order to reduce the ping-pong handover rate. Finally, the effectiveness of the algorithm is verified in different scenarios. Simulation results show that compared with the traditional A3 algorithm, the proposed adaptive handover algorithm based on random suppression can improve the handover trigger probability and handover success probability and avoid the increase of ping-pong handover rate.

Highlights

The long-term evolution for railway (LTE-R) was defined as the generation of railway communication system by the International Union of railways
A new united-decision algorithm is proposed, which takes the received power of reference signal and the received quality of reference signal as the decision conditions at the same time and the corresponding hysteresis thresholds are set according to received signal reference power (RSRP) and Railway Scenario reference quality (RSRQ) respectively. In this algorithm, using elliptic curve to adjust RSRP hysteresis threshold according to train position and speed and random suppression is introduced in the reverse handover decision which is triggered only when the random comparator is on
The core idea is to periodically measure the signals (RSRP or RSRQ) of the source cell and the target cell, if (1) is satisfied, time to trigger (TTT) is a length of time, and when the signal strength of the target cell is higher than the signal strength of serving cell plus a Hys value, the handover is triggered

Summary

INTRODUCTION

The long-term evolution for railway (LTE-R) was defined as the generation of railway communication system by the International Union of railways. The proposed algorithm estimated handover parameters settings based on the weight function, which depends on three bounded functions and the weight of each bounded function This scheme can keep a low ping-pong handover rate and radio link failure (RLF), but the speed of UE was not suitable for high-speed railway scenarios. In this algorithm, using elliptic curve to adjust RSRP hysteresis threshold according to train position and speed and random suppression is introduced in the reverse handover decision which is triggered only when the random comparator is on It reduces the ping-pong handover rate and indirectly improves the handover success rate.

HANDOVER ALGORITHM BASED ON TRADITIONAL A3 EVENT

2: Set up initial values of TTT

ADAPTIVE THRESHOLD ADJUSTMENT ALGORITHM BASED ON ELLIPTIC FUNCTION

HANDOVER MEASUREMENT

Findings

CONCLUSION