TD S2 160051 LS from RAN WG2: LS on NB-IoT work progress in RAN WG2. (RAN WG2)
Abstract: RAN WG2 has started to work on specifying NB-IoT functionality. Please refer to the attached running CR for detailed RAN WG2 progress.
RAN WG2 identified a requirement to differentiate access of 'normal reporting' and 'exceptional reporting' from NB-IoT UE. RAN WG2 foresee that the following values of RRC Establishment Causes may be applicable: mt-Access, mo-Signaling, mo-Data, mo-ExceptionData.
Note: Other new establishment cause, if needed, is FFS. RAN WG2 also agreed to specify a single access
barring mechanism for NB-IoT UE based on barring bitmap per Access Class, and it supports
differentiation of different roaming UEs.
A separate flag is broadcasted which indicates if exception reports are subject to barring bitmap check or not. RAN WG2 assumes that similar as in legacy mechanism, UE AS layer receives {Call Type, Establishment Cause} information from NAS. UE AS layer may use this information for barring evaluation, and eNB may use the Establishment Cause information to perform the necessary prioritization/differentiation per call in the network.
RAN WG2 would like to ask if it is feasible for NAS to indicate to AS that a call generated by NB-IoT UE is an Establishment Cause of 'mo-ExceptionData'.
