There is provided a method including receiving, at a secondary cell, mapping information from a primary cell and using the mapping information to associate a connection request with a user equipment associated with the secondary cell.

There is provided a method including receiving, at a secondary cell, mapping information from a primary cell and using the mapping information to associate a connection request with a user equipment associated with the secondary cell.

A method comprising: receiving at a source serving node (505) an identifier associated with a group of random access channel preambles for allocation by the source serving node (505), the group of random access channel preambles having been reserved at a serving node (503) from available random access channel preambles for the serving node (503); allocating at least one from the group of random access channel preambles, in response to determining a handover from the source serving node (505) to a target serving node (507); and transmitting (515) a message to the target serving node (507), the message comprising the at least one from the group of random access channel preambles.

A method comprising: receiving at a source serving node (505) an identifier associated with a group of random access channel preambles for allocation by the source serving node (505), the group of random access channel preambles having been reserved at a serving node (503) from available random access channel preambles for the serving node (503); allocating at least one from the group of random access channel preambles, in response to determining a handover from the source serving node (505) to a target serving node (507); and transmitting (515) a message to the target serving node (507), the message comprising the at least one from the group of random access channel preambles.

The present application discloses handover methods and apparatuses. One specific embodiment of the handover method comprises receiving a handover request message from a source base station by a target base station; determining whether to add a secondary base station for setting up a dual-connectivity for a user equipment (UE) according to the handover request message; and performing a handover operation and a dual-connectivity setup operation in response to the determination of adding the secondary base station. The dual-connectivity can be set up for the UE during the handover in the embodiments.

A network apparatus includes: a receiver configured to receive, from a base station, information relating to a cell on which a predetermined user terminal camps or a base station; a storage configured to store the information; and a controller configured to decide, based on the information, a base station to which a paging message is transmitted.

A network apparatus includes: a receiver configured to receive, from a base station, information relating to a cell on which a predetermined user terminal camps or a base station; a storage configured to store the information; and a controller configured to decide, based on the information, a base station to which a paging message is transmitted.

An apparatus of a base station (BS) of a radio access network (RAN) comprises memory and processing circuitry. The processing circuitry includes a central unit (CU) portion and a distributed unit (DUI) portion that implement a BS multi-layer protocol stack divided between the CU portion and the DU portion. The processing circuitry initiates a handover to change a serving cell of user equipment (UE). The handover includes a change in a portion of logical layers of the BS multi-layer protocol stack, and the processing circuitry encodes an information element for transmission to the UE indicating logical layers of a UE multi-layer protocol stack implemented in the UE to be reset by the UE in association with the handover.

An apparatus of a base station (BS) of a radio access network (RAN) comprises memory and processing circuitry. The processing circuitry includes a central unit (CU) portion and a distributed unit (DUI) portion that implement a BS multi-layer protocol stack divided between the CU portion and the DU portion. The processing circuitry initiates a handover to change a serving cell of user equipment (UE). The handover includes a change in a portion of logical layers of the BS multi-layer protocol stack, and the processing circuitry encodes an information element for transmission to the UE indicating logical layers of a UE multi-layer protocol stack implemented in the UE to be reset by the UE in association with the handover.

A data transmission method and apparatus are disclosed. The method includes: determining, by a source base station of a terminal in a handover process, first data and a radio air interface protocol sequence number of a data unit used to carry the first data, where the first data includes data that is not acknowledged by a terminal for correct reception during data transmission between the source base station and the terminal. The method further includes sending, by the source base station, the first data and the radio air interface protocol sequence number to a target base station; where the core network connected to the target base station is different from the core network connected to the source base station.