Reducing Handover Outage for Autonomous Vehicles with LTE Hybrid Access

Autonomous vehicle applications require sub-100 ms message latency with a high success probability. While this will be supported by upcoming fifth generation networks, hybrid access technology using multiple LTE connections, may pave the way for the autonomous vehicle applications today. In current LTE networks, handovers often lead to long data interruption. Therefore, we study the handovers and the related data interruption, and how performance can be improved through hybrid access, using redundant transmissions over multiple connections. The study is based on drive tests, where four QualiPoc measurement smartphones are connected to different LTE networks simultaneously, performing synchronized ping latency measurements, and recording handover events. The results show that a handover event during a ping measurement, prolongs the average latency from 60-80 ms to more than 200 ms. However, the handovers do not occur simultaneously in the measured LTE networks. Therefore, hybrid access with two connections is shown to reduce the handover outage by a factor 60. Furthermore, the 99.9 %-tile latency is reduced 66 %, by using two simultaneous connections, as compared to the best single network measurement.