Handling Failures in Secondary Radio Access Failure Handling in Operational 5G Networks

In this work, we conduct a measurement study with three US operators to reveal three types of problematic failure handling on secondary radio access which have not been reported before. Compared to primary radio access failures, secondary radio access failures do not hurt radio access availability but significantly impact data performance, particularly when 5G is used as secondary radio access to boost throughput. Improper failure handling results in significant throughput loss, which is unnecessary in most instances. We then pinpoint the root causes behind these three types of problematic failure handling. When 5G provides higher throughput, failures are more likely to be falsely triggered by a specific event, causing the User Equipment (UE) to unnecessarily lose well-performing 5G connections. Moreover, after failures, the recovery of secondary radio access may fail due to inconsistent parameter settings or be delayed due to missing specific signaling fields. To address these issues, we propose SCGFailure Manager (<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SFM</small>), a solution to optimize the detection and recovery of secondary radio access failures. Our evaluation results demonstrate that <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SFM</small> can effectively avoid 60%-80% of problematic failure handling and double throughput in more than half of failure instances.