Generation Node-B (GNB), user equipment (UE) and methods for handover based on multi-connectivity in new radio (NR) systems

Patent metadata

Field	Value
Publication number	US-12082056-B2
Application number	US-201816479176-A
Country	US
Kind code	B2
Filing date	Feb 1, 2018
Priority date	Feb 2, 2017
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

Embodiments of a generation Node-B (gNB), User Equipment (UE) and methods for communication are generally described herein. A source gNB may operate as a master gNB (MgNB) before a handover. A target gNB may operate as a secondary gNB (SgNB) before the handover. The target gNB may operate as the MgNB after the handover. The target gNB may, as part of operation as the SgNB, transmit a first data packet received from the source gNB for relay to the UE. The target gNB may, as part of operation as the MgNB, transmit, a second data packet received from a serving gateway (SGW) for relay to the UE.

First claim

What is claimed is:

1. An apparatus, comprising:
memory; and
processing circuitry in communication with the memory, wherein the processing circuitry is configured to:
decode a message for a handover of a User Equipment (UE) to a target base station, wherein a source base station is a primary base station for the UE before the handover;
determine, based on the message, that the target base station is to be the primary base station for the UE after the handover;
encode, for transmission to the source base station, a sequence number (SN) status transfer request message that indicates a highest SN of data packets received from the source base station for relay to the UE;
decode, from the source base station, an SN status transfer message that indicates a starting SN for subsequent data packets;
encode, for transmission to the UE while operating as a secondary base station, a first data packet received from the source base station;
encode, for transmission to the UE while operating as the primary base station, a second data packet received from the network; and
refrain from reception of data packets from the source base station for relay to the UE.

2. The apparatus according to claim 1 , the processing circuitry further configured to:
before the handover occurs, decode one or more data packets from the source base station for relay to the UE; and
after the handover occurs:
decode one or more data packets from a serving gateway (SGW) for relay to the UE.

3. The apparatus according to claim 1 , the processing circuitry further configured to:
encode, for transmission to a mobility management entity (MME), a path switch request message that indicates a request for a serving gateway (SGW) to transmit subsequent data packets to the target base station as part of the handover.

4. The apparatus according to claim 1 , the processing circuitry further configured to:
decode, from the UE, a radio resource control (RRC) message that indicates that an RRC reconfiguration at the UE has been completed; and
encode a path switch request message for transmission to a mobility management entity (MME) at least partly in response to reception of the RRC message from the UE.

5. The apparatus according to claim 1 ,
wherein the message is a secondary base station addition request message, and wherein the processing circuitry is further configured to:
encode, for transmission to the source base station, a secondary base station addition request acknowledge message that includes one or more of:
a cell radio network temporary identifier (C-RNTI) to identify the UE in a random access channel (RACH) procedure between the UE and the target base station, and
a security algorithm identifier of the target base station.

6. The apparatus according to claim 5 , the processing circuitry further configured to:
attempt to detect a RACH preamble from the UE;
encode, for transmission to the UE, a RACH message that indicates reception of the RACH preamble; and
encode, for transmission to the source base station, secondary base station reconfiguration complete message that indicates a successful addition as the secondary base station, the successful addition based at least partly on the reception of the RACH preamble.

7. The apparatus according to claim 1 , the processing circuitry further configured to:
decode, from the UE, a buffer status report (BSR) to request an uplink grant for communication to the target base station on a signaling radio bearer (SRB);
encode, for transmission to the UE, the uplink grant; and
decode, from the UE, a radio resource control (RRC) reconfiguration complete message that indicates that an RRC reconfiguration at the UE has been completed.

8. The apparatus according to claim 1 , the processing circuitry further configured to:
decode, from the UE, a request for an uplink grant for communication to the target base station on a signaling radio bearer (SRB); and
encode, for transmission to the UE, a handover command that includes the uplink grant.

9. The apparatus according to claim 1 , the processing circuitry further configured to:
decode, from the UE, a request for an uplink grant for communication to the target base station on a signaling radio bearer (SRB); and
encode, for transmission to the UE, a physical downlink control channel (PDCCH) that includes the uplink grant.

10. The apparatus according to claim 1 , the processing circuitry further configured to:
decode, from the UE, a buffer status report (BSR) to request an uplink grant for communication to the target base station on a signaling radio bearer (SRB),
wherein a bit field of one or more bits indicates that the BSR is intended for the target base station; and
encode, for transmission to the UE, the uplink grant.

11. The apparatus according to claim 1 , the processing circuitry further configured to:
decode, frorn the UE, a request for an uplink grant for communication to the target base station on a signaling radio bearer (SRB); and
encode, for transmission to the UE, a radio resource control (RRC) message that indicates:
the uplink grant, and
an indication that the target base station has begun operation as the primary base station.

12. The apparatus according to claim 1 , the processing circuitry further configured to:
determine a cell radio network temporary identifier (C-RNTI) to identify the UE after the handover is completed; and
encode, for transmission to the UE:
a radio resource control (RRC) message that includes the C-RNTI, or
a handover command that includes the C-RNTI.

13. The apparatus according to claim 1 , wherein the target base station is arranged to operate in accordance with a Previously Presented Radio (NR) protocol.

14. The apparatus according to claim 1 , wherein the apparatus further includes a transceiver to receive the message and to transmit the first and second data packets.

15. The apparatus according to claim 1 , wherein the processing circuitry includes a baseband processor to decode the message and to encode the first and second data packets.

16. A method, comprising:
decoding a message for a handover of a User Equipment (UE) to a target base station, wherein a source base station is a primary base station for the UE before the handover;
determining, based on the message, that the target base station is to be the primary base station for the UE after the handover;
encoding, for transmission to the source base station, a sequence number (SN) status transfer request message that indicates a highest SN of data packets received from the source base station for relay to the UE;
decoding, from the source base station, an SN status transfer message that indicates a starting SN for subsequent data packets;
encoding, for transmission to the UE while operating as a secondary base station, a first data packet received from the source base station;
encoding, for transmission to the UE while operating as the primary base station, a second data packet received from the network; and
refraining from reception of data packets from the source base station for relay to the UE.

17. The method of claim 16 , further comprising:
decoding, before the handover occurs, one or more data packets from the source base station for relay to the UE; and
decoding, after the handover occurs, one or more data packets from a serving gateway (SGW) for relay to the UE.

18. The method of claim 16 , further comprising:
encoding, for transmission to a mobility management entity (MME), a path switch request message that indicates a reque

Assignees

• Apple Inc

Inventors

• Yiu Candy
• Zhu Jing
• Burbidge Richard C
• Jeong Kyeongin
• Palat Sudeep K

Classifications

• H04W36/08

  Reselecting an access point · CPC title

• H04W36/085

  involving beams of access points · CPC title

• H04W36/00695

  using split of the control plane or user plane · CPC title

• H04W36/00692

  using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO] (allocation of physical resources in CoMP or in CA H04L5/0035) · CPC title

• H04W36/30 Primary

  by measured or perceived connection quality data · CPC title