The initiation of Isolated E-UTRAN operation occurs in the event an eNB determines that there is an interruption to normal backhaul connectivity. At this point the eNB can determine if it still has connectivity to other eNBs. It is necessary for services to be set up and a limited backhaul, that might be present, needs to be taken into consideration. The Isolated E-UTRAN needs to inform the UE that it is now working in an Isolated E-UTRAN and an indication to this effect is passed on to the Public Safety user.
An eNB supporting Isolated E-UTRAN operation shall be able to detect a loss of backhaul connection and shall be able to initiate Isolated E-UTRAN operation.
An (N)eNB shall be informed by O&M procedures if its backhaul connection is of limited bandwidth (e.g. a temporary nomadic backhaul deployment or a replacement backhaul in a disaster situation).
Under operator control an NeNB shall be able to initiate Isolated E-UTRAN operation.
When an eNB enters Isolated E-UTRAN operation it shall be able to, if permitted by operator policy, minimize disruption to existing established services between those Public Safety Ues served by the eNB. The eNB shall terminate services that cannot be supported locally by the Isolated E-UTRAN or by the limited backhaul service if that is available.
When an (N)eNB enters Isolated E-UTRAN operation services shall be supported for all Public Safety Ues under the coverage of the Isolated E-UTRAN.
An Isolated E-UTRAN may comprise one or more (N)eNBs.
An (N)eNB supporting Isolated E-UTRAN operation which has initiated Isolated E-UTRAN operation shall attempt to communicate with known peer (N)eNBs for the purpose of commencing Isolated E-UTRAN joint operation.
(N)eNBs engaged in Isolated E-UTRAN joint operation shall be able to exchange user traffic and signalling with other (N)eNBs belonging to the same Isolated E-UTRAN.
An Isolated E-UTRAN shall provide an indication to Public Safety Ues within the coverage area regarding whether limited bandwidth backhaul services are available or whether support is available for local services only. An Isolated E-UTRAN shall be capable of continuing to provide this indication until the Isolated E-UTRAN operation is terminated.
A Public Safety UE served by an Isolated E-UTRAN shall provide an indication to the user that the user is communicating within an Isolated E-UTRAN and whether a limited backhaul service is available or whether support is available for local services only.