GUTI Reallocation Demystified: Cellular Location Tracking with Changing Temporary Identifier

Impact

Our first paperkune2012location in 2012 was discussed in three SA3 meetings held in 2017 across multiple documents: TSG3_086_SophiaSA3 meeting as part of 86th 3GPP meeting held in Sophia (S3-170205, S3-170333, S3-170458). TSGS3_86b_Busan (S3-170758), and TSGS3_87_Ljubljana (S3-171294). GUTI reallocation paper~hong2018guti was the focal point to add unpredictability of GUTI in LTE, discussed in S3-220075. Now in 5G, unpredictability in GUTI after every exposure is mandatory. Unfortunately, a recent report about China and our measurement in Korea show that this is not the case.