# US 2019/0357097 A1 · Handover with zero ms user plane interruption

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2019/0357097 A1
- Document ID: US20190357097A1
- Status: Published application
- Kind: A1
- Application number: 16/480,570
- Filed: 2018-01-31
- Published: 2019-11-21
- Earliest claimed: 2017-02-03
- Assignees: Telefonaktiebolaget LM Ericsson (publ)
- Applicants: Telefonaktiebolaget Lm Ericsson (Publ)
- Inventors: Patrik RUGELAND; Stefan WAGER; Osman Nuri Can YILMAZ
- Web page: https://patentgrep.com/patent/US20190357097A1

## CPC

- H04W 36/0069: {in case of dual connectivity, e.g. decoupled uplink/downlink}
- H04W 12/041: Key generation or derivation
- H04W 56/001: {Synchronization between nodes}
- H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B}
- H04W 92/20: between access points
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

According to certain embodiments, disclosed is a method in a master node (MN) for minimizing user plane interruption delay. The method includes transmitting a handover request message to a secondary node (SN), receiving a handover request acknowledge message from the SN, and transmitting a reconfiguration instruction to a wireless device operating in dual connectivity with the MN and the SN. The reconfiguration instruction may include a new configuration wherein the SN is a target SN and an indication of a trigger used to switch to the new configuration.

## Claims

### Claim 1

A method in a wireless device (115) for minimizing user plane interruption delay, the method comprising:
operating in dual connectivity with a master node (MN) and a secondary node (SN); receiving a reconfiguration instruction from the MN, the reconfiguration instruction comprising:
a new configuration wherein the SN is a target SN; and
an indication of a trigger used to switch to the new configuration;
receiving the trigger from the target SN; and
switching to the new configuration.

### Claim 2 (depends on 1)

The method of claim 1, wherein the trigger to switch to the new configuration is one of:
a dynamic uplink allocation or downlink assignment received from the target SN;
a random access allocation received from the target SN;
a pre-allocated uplink allocation or downlink assignment received from the target SN.

### Claim at position 3

-4. (canceled)

### Claim 5 (depends on 1)

The method of claim 1, wherein the reconfiguration instruction further comprises security key information for the new configuration.

### Claim 6 (depends on 5)

The method of claim 5, wherein the security key information comprises an instruction to utilize a previously derived S-KeNB.

### Claim 7 (depends on 5)

The method of claim 5, wherein the security key information comprises an instruction to calculate a new KeNB and a new S-KeNB.

### Claim 8 (depends on 5)

The method of claim 5, wherein an old KeNB and an old S-KeNB are used while operating in dual connectivity, and the security key information comprises one or more instructions to:
calculate a new KeNB;
calculate a new S-KeNB;
change from the old KeNB to the new KeNB when the trigger is received; and
change from the old S-KeNB to the new S-KeNB when the trigger is received.

### Claim at position 8

-10. (canceled)

### Claim 11 (depends on 1)

The method of claim 1, wherein operating in dual connectivity comprises using a master cell group (MCG) bearer with the MN and a secondary cell group (SCG) bearer with the SN, and the reconfiguration instruction further comprises instructions to:
switch the MCG bearer to the target SN when the trigger is received; and
switch the SCG bearer to the MN when the trigger is received.

### Claim 12 (depends on 1)

The method of claim 1, wherein operating in dual connectivity comprises using a split MCG bearer, and the reconfiguration instruction further comprises instructions to:
switch a MCG part of the split MCG bearer to the target SN when the trigger is received; and
switch a secondary cell group (SCG) part of the MCG bearer to the MN when the trigger is received.

### Claim 13 (depends on 1)

The method of claim 1, wherein operating in dual connectivity comprises using a split secondary cell group (SCG) bearer, and the reconfiguration instruction further comprises instructions to:
switch MCG part of the split SCG bearer to the target SN when the trigger is received; and
switch a SCG part of the split SCG bearer to the MN when the trigger is received.

### Claim at position 12

-16. (canceled)

### Claim 17

A wireless device for minimizing user plane interruption delay, the wireless device comprising:
processing circuitry configured to operate in dual connectivity with a master node (MN) and a secondary node (SN);
a transceiver operably coupled the processing circuitry, the transceiver configured to:
receive a reconfiguration instruction from MN, the reconfiguration instruction comprising:
a new configuration wherein the SN is a target SN; and
an indication of a trigger used to switch to the new configuration;
receive the trigger from the target SN; and
the processing circuitry further configured to switch to the new configuration.

### Claim 18 (depends on 17)

The wireless device of claim 17, wherein the trigger to switch to the new configuration is a dynamic uplink allocation or downlink assignment received from the target SN.

### Claim 19 (depends on 17)

The wireless device of claim 17, wherein the trigger to switch to the new configuration is one of:
a random access allocation received from the target SN; or
a pre-allocated uplink allocation or downlink assignment received from the target SN.

### Claim 20

(canceled)

### Claim 21 (depends on 17)

The wireless device of claim 17, wherein the reconfiguration instruction further comprises security key information for the new configuration.

### Claim 22 (depends on 21)

The wireless device of claim 21, wherein the security key information comprises an instruction to utilize a previously derived S-KeNB.

### Claim 23 (depends on 21)

The wireless device of claim 21, wherein the security key information comprises an instruction to calculate a new KeNB and a new S-KeNB.

### Claim 24 (depends on 21)

The wireless device of claim 21, wherein an old KeNB and an old S-KeNB are used while operating in dual connectivity, and the security key information comprises one or more instructions to:
calculate a new KeNB;
calculate a new S-KeNB;
change from the old KeNB to the new KeNB when the trigger is received; and
change from the old S-KeNB to the new S-KeNB when the trigger is received.

### Claim 25 (depends on 17)

The wireless device of claim 17, wherein the transceiver (910) is further operable to receive, from the MN, an indication in a PDCP message of one or more security keys to utilize in the new configuration.

### Claim 26 (depends on 25)

The wireless device of claim 25, wherein an old KeNB and an old S-KeNB are used while operating in dual connectivity, and the processing circuitry (920) is further configured to:
calculate a new KeNB;
calculate a new S-KeNB;
change from the old KeNB to the new KeNB when the trigger is received; and
change from the old S-KeNB to the new S-KeNB when the trigger is received.

### Claim 27 (depends on 17)

The wireless device of claim 17, wherein operating in dual connectivity comprises using a master cell group (MCG) bearer with the MN and a secondary cell group (SCG) bearer with the SN, and the reconfiguration instruction further comprises instructions to:
switch the MCG bearer to the target SN when the trigger is received; and
switch the SCG bearer to the MN when the trigger is received.

### Claim 28 (depends on 17)

The wireless device of claim 17, wherein operating in dual connectivity comprises using a split MCG bearer, and the reconfiguration instruction further comprises instructions to:
switch a MCG part of the split MCG bearer to the target SN when the trigger is received; and
switch a secondary cell group (SCG) part of the MCG bearer to the MN when the trigger is received.

### Claim 29 (depends on 17)

The wireless device of claim 17, wherein operating in dual connectivity comprises using a split SCG bearer, wherein the reconfiguration instruction further comprises instructions to:
switch MCG part of the split SCG bearer to the target SN when the trigger is received; and
switch a SCG part of the split SCG bearer to the MN when the trigger is received.

### Claim at position 26

-32. (canceled)

### Claim 33

A method in a master node (MN) for minimizing user plane interruption delay, the method comprising:
transmitting a handover request message to a secondary node (SN);
receiving a handover request acknowledge message from the SN;
transmitting a reconfiguration instruction to a wireless device operating in dual connectivity with the MN and the SN, the reconfiguration instruction comprising:
a new configuration wherein the SN is a target SN; and
an indication of a trigger used to switch to the new configuration.

### Claim 34 (depends on 33)

The method of claim 33, wherein the trigger is one of:
a dynamic uplink allocation or downlink assignment sent from the target SN;
a random access allocation sent from the target SN; or
a pre-allocated uplink allocation or downlink assignment sent from the target SN.

### Claim at position 29

35-36. (canceled)

### Claim 37 (depends on 33)

The method of claim 33, wherein the reconfiguration instruction further comprises security key information for the new configuration.

### Claim 38 (depends on 37)

The method of claim 37, wherein the security key information comprises an instruction to utilize a previously derived S-KeNB.

### Claim 39 (depends on 37)

The method of claim 37, wherein the security key information comprises an instruction to calculate a new KeNB and a new S-KeNB.

### Claim 40 (depends on 37)

The method of claim 37, wherein the security key information comprises an instruction to:
calculate a new KeNB;
calculate a new S-KeNB;
change from the old KeNB to the new KeNB when the trigger is received; and
change from the old S-KeNB to the new S-KeNB when the trigger is received.

### Claim 41 (depends on 33)

The method of claim 33, further comprising transmitting, to the wireless device, an indication in a PDCP message of one or more security keys to utilize in the new configuration.

### Claim 42 (depends on 33)

The method of claim 33, further comprising forwarding downlink data to the target SN.

### Claim 43 (depends on 42)

The method of claim 42, further comprising:
duplicating the downlink data so that the downlink data is available for use by the MN and for forwarding to the target SN.

### Claim 44 (depends on 42)

The method of claim 42, wherein forwarding downlink data to the target SN starts before the new configuration is implemented.

### Claim 45 (depends on 33)

The method of claim 33, further comprising transmitting, to the wireless device, an indication in a RRC message of one or more security keys to utilize in the new configuration.

### Claim at position 39

-73. (canceled)