Method of intra-next-generation-node-B mobility
Systems, methods, apparatuses, and computer program products for a method of mobility between distributed units with a local control plane are provided. For example, a method can include detecting, at a target distributed unit, a handover based on an indication from a source distributed unit after a handover command has been sent to a user equipment to hand over from the source distributed unit to the target distributed unit. The method can also include sending, from the target distributed unit to a central unit user plane, a data transmission resume notification, to trigger to the central unit user plane to resume downlink data transmission toward the target distributed unit. The downlink data transmission was previously suspended by instructions from a source distributed unit to the central unit user plane when the handover was initiated from the source distributed unit to the target distributed unit.
1 . An apparatus, comprising:
at least one processor; and
at least one memory including computer program code,
wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:
receive, by a central unit user plane of the apparatus from a source distributed unit, a tunnel endpoint identifier container, the container containing downlink tunnel endpoint identifiers of data radio bearers prepared at a target cell, wherein the container is provided upon preparation of the target cell; or
receive, by the central unit user plane from a target distributed unit, the tunnel endpoint identifier container, the container containing downlink tunnel endpoint identifiers of data radio bearers prepared at the target cell, wherein the container is provided upon reception of a message from the source distributed unit to proceed with handing over from the source distributed unit to the target distributed unit in the target cell; or
receive, by the central unit user plane from the target distributed unit, the tunnel endpoint identifier container, the container containing downlink tunnel endpoint identifiers of data radio bearers prepared at the target cell, wherein the container is provided upon successful random access completion by a user equipment being handed over from the source distributed unit to the target distributed unit;
determine, by a central unit control plane of the apparatus, security keys for the target distributed unit; and
send the security keys to the target distributed unit,
wherein the determining comprises precomputing the security keys by the central unit control plane, wherein the sending comprises sharing, by the central unit control plane, the security keys with the target distributed unit and a user equipment being handed over from a source distributed unit to the target distributed unit, and wherein the precomputing is performed prior to the handover, and
wherein the precomputing the security keys is performed for a case in which the source distributed unit and the target distributed unit are in different operator management or security domains.
2 . The apparatus of claim 1 , wherein the receiving the tunnel endpoint identifier container comprises receiving the tunnel endpoint identifier container directly at the central unit user plane over user-plane or indirectly at the central unit user plane via the central unit control plane using control plane signaling.
3 . The apparatus of claim 1 , wherein the apparatus is further caused to:
receive, by a central unit control plane of the apparatus, the tunnel endpoint identifier container, the container containing downlink tunnel endpoint identifiers of data radio bearers prepared at a target cell.
4 . The apparatus of claim 1 , wherein the precomputing is performed proactively by the central unit control plane or wherein the precomputing is triggered by identification of a potential target distributed unit by the source distributed unit using distinguishing parameters specific to the target distributed unit.
5 . The apparatus of claim 1 , wherein the apparatus is further caused to:
receive a list of potential target distributed units from the source distributed unit, wherein the precomputing is performed for each potential target distributed unit in the list.