Apple Inc.
Security framework for MSG3 and MSG4 in early data transmission

Abstract:

Systems and methods of a security framework for an RRC connection are described. The UE receives a release message that comprises a current Next Hop Chaining Counter (NCC). The UE derives a new K.sub.eNB* using the current NCC and transmits an EDT RA preamble to same or a different base station. After receiving an RAR with an uplink allocation, the UE transmits a RRCConnectionResumeRequest message. The UE transmits uplink data encrypted using K.sub.eNB* if the uplink allocation includes a data allocation sufficient for the data, fall backs to a legacy RRC connection procedure in which the stored K.sub.eNB* is discarded and then K.sub.eNB* is re-derived if the data allocation is insufficient for the data due to a CE level change, and fall backs to a legacy RRC connection procedure in which the stored K.sub.eNB* is used instead of discarding K.sub.eNB* if the uplink allocation excludes the data allocation.