# US 2019/0320482 A1 · Link re-establishment method, apparatus, and system

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- Number: US 2019/0320482 A1
- Document ID: US20190320482A1
- Status: Published application
- Kind: A1
- Application number: 16/455,739
- Filed: 2019-06-27
- Published: 2019-10-17
- Earliest claimed: 2016-12-30
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Li HU; Jing CHEN; Yinghui YU
- Web page: https://patentgrep.com/patent/US20190320482A1

## CPC

- H04W 76/19: Connection re-establishment
- H04W 8/08: Mobility data transfer
- H04W 12/06: Authentication
- H04W 12/10: Integrity
- H04W 76/25: Maintenance of established connections
- H04W 76/27: Transitions between radio resource control [RRC] states
- H04W 80/02: Data link layer protocols
- H04W 12/72: Subscriber identity
- H04W 76/00: Connection management
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

The present disclosure discloses a link re-establishment method, an apparatus, and a system. The method includes: obtaining, by user equipment UE, a MAC of the UE based on a NAS integrity key and a first MAC generation parameter, where the first MAC generation parameter includes an identifier of the UE; sending, by the UE, a re-establishment request message to a target RAN, where the re-establishment request message includes the MAC and the first MAC generation parameter; and receiving, by the UE, a re-establishment response message of the target RAN. The UE triggers, by sending the re-establishment request message, a CP functional entity to perform authentication on the UE. This resolves a prior-art problem that an excessively long time is consumed to re-establish a connection to a target RAN by using an RAU procedure, increases a speed of re-establishing a connection between UE and a network, and improves user experience.

## Claims

### Claim 1

A communication system comprising: a control plane (CP) functional entity and a target radio access node (RAN), wherein
the target RAN is configured to receive a re-establishment request message from user equipment (UE), and send a first message to the CP functional entity based on the re-establishment request message, wherein the re-establishment request message comprises a second message authentication code (MAC) generation parameter and a MAC of the UE, the first message comprises the second MAC generation parameter and the MAC;
the CP functional entity, configured to receive the first message from the target RAN, and verify the MAC based on the first message; when verification of the MAC succeeds, send a context of the UE to the target RAN;
the target RAN, further configured to receive the context of the UE, and send a re-establishment response message to the UE.

### Claim 2 (depends on 1)

The communication system according to claim 1, wherein the second MAC generation parameter comprises an identifier of the UE, and when verifying the MAC based on the first message, the CP functional entity is further configured to:
obtain a non-access stratum (NAS) integrity key of the UE based on the identifier of the UE in the second MAC generation parameter; and
verify the MAC based on the NAS integrity key of the UE and the second MAC generation parameter.

### Claim 3 (depends on 1)

The communication system according to claim 1, wherein the second MAC generation parameter comprises a partial field of an NAS count.

### Claim 4 (depends on 1)

The communication system according to claim 1, wherein the re-establishment request message is a radio resource control (RRC) connection re-establishment request message, and the re-establishment response message is an RRC connection re-establishment message.

### Claim 5 (depends on 1)

The communication system according to claim 1, further comprising a source RAN;
wherein the CP functional entity is further configured to send a second message to the source RAN when verification of the MAC succeeds, wherein the second message is used to request the source RAN to send data of the UE to the CP functional entity; and
the source RAN is configured to send data of the UE stored on the source RAN to the CP functional entity.

### Claim 6 (depends on 5)

The communication system according to claim 5, wherein the second message comprises an identifier of the UE;
the source RAN is further configured to delete the context of the UE based on the identifier of the UE.

### Claim 7 (depends on 1)

The communication system according to claim 1, further comprising the UE;
wherein the UE is configured to obtain the MAC of the UE based on a NAS integrity key and a first MAC generation parameter, and send the re-establishment request message to the target RAN.

### Claim 8 (depends on 7)

The communication system according to claim 7, wherein the first MAC generation parameter comprises an NAS count.

### Claim 9

A communication method applied to a communication system comprising a control plane (CP) functional entity and a target radio access node (RAN), the method comprising:
receiving, by the target radio access node (RAN), a re-establishment request message from user equipment (UE);
sending, by the target RAN, a first message to the control plane (CP) functional entity based on the re-establishment request message, wherein the re-establishment request message comprises a second message authentication code (MAC) generation parameter and an MAC of the UE, the first message comprises the second MAC generation parameter and the MAC;
receiving, by the CP functional entity, the first message from the target RAN;
verifying, by the CP functional entity, the MAC based on the first message;
when verification of the MAC succeeds, sending, by the CP functional entity, a context of the UE to the target RAN;
receiving, by the target RAN, the context of the UE; and
sending, by the target RAN, a re-establishment response message to the UE.

### Claim 10 (depends on 9)

The communication method according to claim 9, wherein the second MAC generation parameter comprises an identifier of the UE, and wherein verifying the MAC based on the first message comprises:
obtaining, by the CP functional entity, a non-access stratum (NAS) integrity key of the UE based on the identifier of the UE in the second MAC generation parameter; and
verifying, by the CP functional entity, the MAC based on the NAS integrity key of the UE and the second MAC generation parameter.

### Claim 11 (depends on 9)

The communication method according to claim 9, wherein the second MAC generation parameter comprises a partial field of an NAS count.

### Claim 12 (depends on 9)

The communication method according to claim 9, wherein the re-establishment request message is a radio resource control (RRC) connection re-establishment request message, and the re-establishment response message is an RRC connection re-establishment message.

### Claim 13 (depends on 9)

The communication method according to claim 9, further comprising;
sending, by the CP functional entity, a second message to a source RAN comprised in the communication system, when verification of the MAC succeeds, wherein the second message is used to request the source RAN to send data of the UE to the CP functional entity; and
sending, by the source RAN, data of the UE stored on the source RAN to the CP functional entity.

### Claim 14 (depends on 13)

The communication method according to claim 13, wherein the second message comprises an identifier of the UE; and the method further comprises:
deleting, by the source RAN, the context of the UE based on the identifier of the UE.

### Claim 15

A communication apparatus comprising: at least one processor and a memory; wherein
the memory, configured to store a program; and
the at least one processor, configured to execute the program stored in the memory to enable the communication apparatus to implement the following operations:
receiving a first message from a target radio access node (RAN), wherein the first message comprises a second message authentication code (MAC) generation parameter and an MAC of user equipment (UE);
verifying the MAC based on the first message; and
when verification of the MAC succeeds, sending a context of the UE to the target RAN.

### Claim 16 (depends on 15)

The communication apparatus according to claim 15, wherein the second MAC generation parameter comprises a partial field of a non-access stratum (NAS) count.

### Claim 17 (depends on 15)

The communication apparatus according to claim 15, wherein the second MAC generation parameter comprises an identifier of the UE, and the verifying the MAC based on the first message comprises:
obtaining an NAS integrity key of the UE based on the identifier of the UE in the second MAC generation parameter; and
verifying the MAC based on the NAS integrity key of the UE and the second MAC generation parameter.

### Claim 18 (depends on 15)

The communication apparatus according to claim 15, wherein the operations further comprise:
when verification of the MAC succeeds, sending a second message to a source RAN, wherein the second message is used to request the source RAN to send data of the UE to the CP functional entity.

### Claim 19 (depends on 18)

The communication apparatus according to claim 18, wherein the operations further comprise:
receiving data of the UE from the source RAN; and
sending the data of the UE to the UE through the target RAN.

### Claim 20 (depends on 15)

The communication apparatus according to claim 15, wherein the communication apparatus is a mobility management entity (MME).