We claim:
1. A base station (212) comprising:
a wireless transceiver to communicate with a user equipment (UE) (210); a processor to:
establish a connection as a serving master base station (212) through the wireless transceiver to the UE (210), the UE (210) in dual connectivity with the serving base station (212) and a secondary base station (213);
determine to handover the UE (210) from the serving base station (212) to a target base station (214); and
in response to the determination, handover both the UE (210) and the secondary base station (213) to the target base station (214),
wherein to handover the secondary base station (213) to the target base station (214), the processor is to:
send a handover request to the target base station (214), the handover
request to instruct the target base station (214) to keep a secondary cell group
(SCG) corresponding to the secondary base station (213); and
send a command to the secondary base station (213) comprising a list of
cells to keep in the SCG and instructions to change the secondary base station
(213) to a master cell group (MCG) corresponding to the target base station (214).
2. The base station (212) as claimed in claim 1, wherein the wireless transceiver is to receive
a measurement report from the UE (210) indicating at least a strength of signals received by
the UE (210) from the base station (212), and wherein the processor is to:
process the measurement report to determine that the UE (210) is moving from a first cell coverage area corresponding to the serving base station (212) to a second cell coverage area corresponding to the target base station (214); and
in response, make the determination to handover the UE (210) from the serving base station (212) to the target base station (214).
3. The base station (212) as claimed in claim 2, wherein the measurement report comprises a
reference signal received power (RSRP) or reference signal received quality (RSRQ).

4. The base station (212) as claimed in claim 1, wherein to handover both the UE (210) and
the base station (213) to the target base station (214), the processor is to:
send a radio resource control (RRC) connection reconfiguration message to the UE (210) through the wireless transceiver, the RRC connection reconfiguration message including a field indicating a list of cells to keep in the SCG.
5. The base station (212) as claimed in claim 1, wherein the processor is to:
receive, from the secondary base station (213), a response to the command; send a sequence number status transfer and data forwarding message to the target base station (214); and
receive, from the target base station (214), a UE (210) context release message.
6. The base station (212) as claimed in claim 1, wherein the serving base station (212) is to communicate with the secondary base station (213) and the serving base station (212) through a non-ideal backhaul interface (X2) (120).
7. A user equipment (UE) (210) comprising:.
a plurality of wireless transceivers to receive user data through a split bearer from a first base station (213) and a second base station (213); and a.circuitry to:
periodically measure a reference signal received power (RSRP) or reference signal received quality (RSRQ) of a link with the first base station (212);
send, through a first wireless transceiver of the plurality of wireless transceivers, an RSRP or RSRQ measurement report to the first base station (212);
receive, from the first base station (212), a message that indicates an initiation of a split bearer handover of the UE (210) from the first base station (212) to a third base station (214); and
in response to the message, remain connected to the second base station (213) during the split bearer handover of the UE (210) from the first base station (212) to the third base station (214),
wherein to handover the second base station (213) from the first base station (212) to the third base station (214), the circuitry is to:

send a handover request to the third base station (214), the handover request to instruct the third base station (214) to keep a secondary cell group (SCG) corresponding to the second base station (213);
send a command to the second base station (213) comprising a list of cells to keep in the SCG and instructions to change the second base station (213) to a master cell group (MCG) corresponding to the third base station (214).
8. The UE (210) as claimed in claim 7, wherein the circuitry is to: .
determine a measurement event trigger based on the measured RSRP or RSRQ with the link with the first base station (212); and
wait for a predetermined time to trigger (TTT) timer to expire before sending the RSRP or RSRQ measurement report to the first base station (212).
9. The UE (210) as claimed in claim 7, wherein the message that indicates the initiation of the
split bearer handover comprises a radio resource control (RRC) connection reconfiguration
message including a field indicating the list of cells to keep in the secondary cell group (SCG)
corresponding to the second base station (213).
10. The UE (210) as claimed in claim 9, wherein in response to receiving the RRC connection reconfiguration message, the circuitry is to communicate through a second wireless transceiver of the plurality of wireless transceivers with the third base station (214) to perform a random access procedure to establish a connection between the UE (210) and the third base station (214).
11. The UE (210) as claimed in claim 7, wherein the UE (210) comprises at least one of an antenna, a touch sensitive display screen, a speaker, a microphone, a graphics processor, an application processor, internal memory, a non-volatile memory port, or combinations thereof.
12. A node (213) to communicate with a wireless communication system, the node (212) comprising:
one or more processors to:
associate the node (213) with a secondary cell group (SCG) of the wireless communication system;
establish a connection with a user equipment (UE) (210);

cooperate with a first node (212) in a first master cell group (MCG) to provide dual connectivity to the UE (210);
receive, from the first node (212), a command to change the dual connectivity of the UE (210) from the first node (212) in the first MCG to a second node (214) in a second MCG, wherein the command received from the first node (212) in the first MCG comprises a list of cells to keep in the SCG; and
in response to the command, maintain the connection with the UE (210) and change from cooperation with the first node (212) to cooperation with the second node (214) to provide the dual connectivity to the UE (210).
13. The node (213) as claimed in claim 12, wherein in response to the command received from the first node (212) in the first MCG, the node (212) is to send a message to the first node (212) in the first MCG and the second node (214) in the second MCG comprising the list of cells to keep in the SCG.
14. The node (213) as claimed in claim 12, wherein the node (212) is to communicate with at least one of the first node (212) in the first MCG and the second node (214) in the second MCG through a non-ideal backhaul interface (X2) (120).
15. A handover method implemented by a processor in a first master node (212), the handover method comprising:
sending a request to handover a user equipment (UE) (210) from the first master node (212) to a second master node (214) while keeping a secondary node (213) connected to the UE (210);
sending a message to the UE (210) to disconnect from the first master node (212) and to connect with the second master node (214) while maintaining a connection with the secondary node (213);
performing a random access procedure for establishing a connection between the UE (210) and the second master node (214); and
wherein handover from the secondary node (213) to the second master node (214) includes:
instructing the second master node (214) to keep a secondary cell group (SCG)
corresponding to the secondary node (213),

sending a command to the secondary node (213) comprising a list of cells to keep in the SCG and instructions to change the secondary node (213) to a master cell group (MCG) corresponding to the second master node (214),
terminating a connection between the UE (210) and the first master node (212).
16. The handover method as claimed in claim 15, wherein the handover method comprises:
receiving, from the UE (210), a measurement report comprising a reference signal received power (RSRP) or reference signal received quality (RSRQ); and
in response to the measurement report, sending the request to handover the UE (210) from the first master node (212) to the second master node (214).
17. The handover method as claimed in claim 15, wherein sending the request to handover the
UE (210) comprises sending the request through a non-ideal backhaul interface (X2) (120).