QoE-based Log Collection in Minimization of Drive Tests

摘要

We have been conducting research into the creation of a coverage map or a map of coverage holes for mobile access systems, such as cellular systems, by collecting coverage information that includes radio signal information and location information from mobile terminals. A similar study started in 3GPP, known as MDT (Minimization of Drive Tests). In such studies, poorer radio measurements than a pre-defined threshold are one of triggers to collect coverage information. However, it is not sufficient to collect this information based only on the radio measurements criteria since it would be hard to detect an event of quality degradation that is caused, for example, by mobile traffic congestion, which is also a target event that the coverage map should include and against which telecom operators take necessary measures such as certain parameter tunings at base stations and deployment of new base stations. In this paper, we propose a method in which a mobile terminal records traffic behavior, such as an increasing rate of received traffic volume and the ratio of downlink packets to uplink packets, per application used, and deduces the QoE (Quality of Experience) of a new communication session based on the recorded traffic behaviors. The information collection trigger based on the proposed method would enable operators to gather information in the event of user experience deterioration, for instance, slower web response than usual. We executed preliminary evaluations in which two research participants used smartphones where the proposed method was implemented, and found that the method correctly judged sessions of poor QoE as being of poor qualities in 75 percent probability.