# US 11,122,639 B2 · Technique for providing multiple Radio Access Network connectivity to terminal device

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- Number: US 11,122,639 B2
- Document ID: US11122639B2
- Status: Granted
- Kind: B2
- Application number: 16/339,457
- Filed: 2016-10-17
- Published: 2020-02-13
- Granted: 2021-09-14
- Earliest claimed: 2016-10-17
- Assignees: Telefonaktiebolaget LM Ericsson (publ)
- Applicants: Telefonaktiebolaget LM Ericsson (publ)
- Inventors: Håkan Axelsson; Rasmus Axén; Rui Fan; Stefan Johansson; Paul Schliwa-Bertling
- Web page: https://patentgrep.com/patent/US11122639B2

## CPC

- H04W 76/15: Setup of multiple wireless link connections
- H04W 76/16: Involving different core network technologies, e.g. a packet-switched [PS] bearer in combination with a circuit-switched [CS] bearer
- H04L 9/0819: {Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) (network architectures or network communication protocols for key distribution in a packet data network H04L63/062)}
- H04W 12/033: of the user plane, e.g. user's traffic
- H04L 2209/80: Wireless
- H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals
- 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)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A technique for providing multiple connectivity to a terminal device by at least a first Radio Access Network, RAN entity and a second RAN entity is disclosed. The first RAN entity serves as a control plane anchor and the split bearer will be anchored at the second RAN entity. The method comprises triggering, by the first RAN entity, the second RAN entity to set up the split bearer on the user plane. The split bearer comprises at least a first bearer leg from the second RAN entity via the first RAN entity to the terminal device and a second bearer leg from the second RAN entity to the terminal device without going through the first RAN entity.

## Claims

### Claim 1

A method of providing multiple connectivity to a terminal device via at least a first Radio Access Network (RAN) entity and a second RAN entity, wherein the first RAN entity serves as a control plane anchor, the method comprising:
the first RAN entity:
evaluating whether to set up a split bearer at the first RAN entity or at the second RAN entity;
deciding to set up the split bearer at the second RAN entity;
triggering the second RAN entity to set up the split bearer on a user plane;
triggering setup of the split bearer at the terminal device; and
triggering setup of a flow control receiver entity for a flow control link between a Radio Link Control (RLC) entity of the first RAN entity and a Packet Data Convergence Protocol (PDCP) entity of the second RAN entity,
wherein the split bearer comprises at least:
a first bearer leg from the second RAN entity via the first RAN entity to the terminal device; and
a second bearer leg from the second RAN entity to the terminal device without going through the first RAN entity.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
obtaining, by the first RAN entity, a user plane encryption key for the split bearer; and
sending the user plane encryption key to the second RAN entity for application by the second RAN entity to data packets on at least the second bearer leg.

### Claim 3 (depends on 2)

The method of claim 2, wherein the user plane encryption key is KUPenc according to Long Term Evolution (LTE) Release 12 or later.

### Claim 4 (depends on 1)

The method of claim 1, further comprising triggering:
setup of the RLC entity and/or a Medium Access Control (MAC) entity at the first RAN entity, and an RLC entity and/or a MAC entity for the terminal device; and/or
setup of the PDCP entity, an RLC entity, and/or a MAC entity at the second RAN entity, a PDCP entity, an RLC entity, and/or a MAC entity and for the terminal device.

### Claim 5 (depends on 1)

The method of claim 1, further comprising informing a core network that the split bearer is anchored at the second RAN entity by sending a network address of the second RAN entity to the core network.

### Claim 6 (depends on 1)

The method of claim 1, wherein the terminal device is triggered to set up the split bearer responsive to receipt, at the first RAN entity, of a bearer setup acknowledgement from the second RAN entity.

### Claim 7 (depends on 1)

The method of claim 1, wherein the first RAN entity serves as the control plane anchor for mobility management in regard of the terminal device; and/or Radio Resource Control (RRC) in regard of the terminal device.

### Claim 8

A method of providing multiple connectivity to a terminal device via at least a first Radio Access Network (RAN) entity and a second RAN entity, wherein the first RAN entity serves as a control plane anchor, the method comprising:
setting up, at the second RAN entity and in response to being triggered by the first RAN entity, a split bearer on a user plane;
setting up a flow control transmitter entity for a flow control link between a Packet Data Convergence Protocol (PDCP) entity of the second RAN entity and a Radio Link Control (RLC) entity of the first RAN entity,
wherein the split bearer comprises at least:
a first bearer leg from the second RAN entity to the terminal device without going through the first RAN entity; and
a second bearer leg from the second RAN entity via the first RAN entity to the terminal device.

### Claim 9 (depends on 8)

The method of claim 8, further comprising:
receiving a user plane encryption key for the split bearer from the first RAN entity; and
applying the user plane encryption key received from the first RAN entity to data packets on at least the first bearer leg.

### Claim 10 (depends on 8)

The method of claim 8, further comprising setting up the PDCP entity, an RLC entity, and/or a Medium Access Control (MAC) entity at the second RAN entity, and a PDCP entity, an RLC entity, and/or a MAC entity for the terminal device.

### Claim 11 (depends on 10)

The method of claim 10, further comprising sending a bearer setup acknowledgement to the first RAN entity after at least one of the following has been set up:
the PDCP entity, the RLC entity, and the MAC entity; and
the flow control transmitter entity for the flow control link between the PDCP entity of the second RAN entity and the RLC entity of the first RAN entity.

### Claim 12

A Radio Access Network (RAN) entity for a system capable of providing multiple connectivity to a terminal device via at least a first RAN entity and a second RAN entity, wherein the first RAN entity serves as a control plane anchor, the RAN entity being the first RAN entity and comprising:
processing circuitry;
memory containing instructions executable by the processing circuitry whereby the RAN entity is operative to:
evaluate whether to set up a split bearer at the first RAN entity or at the second RAN entity; and
decide to set up the split bearer at the second RAN entity;
trigger the second RAN entity to set up the split bearer on a user plane;
trigger setup of the split bearer at the terminal device; and
trigger setup of a flow control receiver entity for a flow control link between a Radio Link Control (RLC) entity of the first RAN entity and a Packet Data Convergence Protocol (PDCP) entity of the second RAN entity,
wherein the split bearer comprises at least:
a first bearer leg from the second RAN entity via the first RAN entity to the terminal device; and
a second bearer leg from the second RAN entity to the terminal device without going through the first RAN entity.

### Claim 13 (depends on 12)

The RAN entity of claim 12, wherein the instructions are such that the RAN entity is further operative to:
obtain a user plane encryption key for the split bearer; and
send the user plane encryption key to the second RAN entity for application by the second RAN entity to data packets on at least the second bearer leg.

### Claim 14 (depends on 13)

The RAN entity of claim 13, wherein the user plane encryption key is KUPenc according to Long Term Evolution (LTE) Release 12 or later.

### Claim 15 (depends on 12)

The RAN entity of claim 12, wherein the instructions are such that the RAN entity is further operative to trigger:
setup of the RLC entity and/or a Medium Access Control (MAC) entity at the first RAN entity, and an RLC entity and/or a MAC entity for the terminal device; and/or
setup of the PDCP entity, an RLC entity, and/or a MAC entity at the second RAN entity, and a PDCP entity, an RLC entity, and/or a MAC entity for the terminal device.

### Claim 16 (depends on 12)

The RAN entity of claim 12, wherein the instructions are such that the RAN entity is further operative to inform a core network that the split bearer is anchored at the second RAN entity by sending a network address of the second RAN entity to the core network.

### Claim 17 (depends on 12)

The RAN entity of claim 12, wherein the instructions are such that the RAN entity is further operative to trigger the terminal device to set up the split bearer responsive to receipt of a bearer setup acknowledgement from the second RAN entity.

### Claim 18 (depends on 12)

The RAN entity of claim 12, wherein the first RAN entity serves as the control plane anchor for:
mobility management in regard of the terminal device; and/or
Radio Resource Control (RRC) in regard of the terminal device.

### Claim 19

A Radio Access Network (RAN) entity for a system capable of providing multiple connectivity to a terminal device via at least a first RAN entity and a second RAN entity, wherein the first RAN entity serves as control plane anchor, the RAN entity being the second RAN entity and comprising:
processing circuitry;
memory containing instructions executable by the processing circuitry whereby the RAN entity is operative to:
set up, at the second RAN entity and in response to being triggered by the first RAN entity, a split bearer on a user plane;
set up a flow control transmitter entity for a flow control link between a Packet Data Convergence Protocol (PDCP) entity of the second RAN entity and a Radio Link Control (RLC) entity of the first RAN entity,
wherein the split bearer comprises at least:
a first bearer leg from the second RAN entity to the terminal device without going through the first RAN entity; and
a second bearer leg from the second RAN entity via the first RAN entity to the terminal device.

### Claim 20 (depends on 19)

The RAN entity of claim 19, wherein the instructions are such that the RAN entity is further operative to:
receive a user plane encryption key for the split bearer from the first RAN entity; and
apply the user plane encryption key received from the first RAN entity to data packets on at least the first bearer leg.

### Claim 21 (depends on 19)

The RAN entity of claim 19, wherein the instructions are such that the RAN entity is further operative to set up the PDCP entity, an RLC entity, and/or a Medium Access Control (MAC) entity at the second RAN entity, and a PDCP entity, an RLC entity and/or a MAC entity for the terminal device.

### Claim 22 (depends on 21)

The RAN entity of claim 21, wherein the instructions are such that the RAN entity is further operative to send a bearer setup acknowledgement to the first RAN entity after at least one of the following has been set up:
the PDCP entity, the RLC entity and the MAC entity; and
the flow control transmitter entity for the flow control link between the PDCP entity of the second RAN entity and the RLC entity of the first RAN entity.