# US 2019/0174367 A1 · Communication system

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- Number: US 2019/0174367 A1
- Document ID: US20190174367A1
- Status: Published application
- Kind: A1
- Application number: 16/267,091
- Filed: 2019-02-04
- Published: 2019-06-06
- Earliest claimed: 2013-01-17
- Assignees: NEC Corporation
- Applicants: NEC Corporation
- Inventors: Vivek SHARMA
- Web page: https://patentgrep.com/patent/US20190174367A1

## CPC

- H04W 36/0038: {of security context information}
- H04W 12/02: Protecting privacy or anonymity, e.g. protecting personally identifiable information [PII]
- H04W 12/033: of the user plane, e.g. user's traffic
- H04W 12/037: of the control plane, e.g. signalling traffic
- H04W 12/04: Key management, e.g. using generic bootstrapping architecture [GBA]
- H04W 12/041: Key generation or derivation
- H04W 12/0431: Key distribution or pre-distribution; Key agreement
- H04W 12/0433: Key management protocols
- H04W 16/32: Hierarchical cell structures
- H04L 9/0861: {Generation of secret information including derivation or calculation of cryptographic keys or passwords}
- H04L 2209/24: Key scheduling, i.e. generating round keys or sub-keys for block encryption
- H04W 36/00695: {using split of the control plane or user plane}
- H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B}
- 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 communication system is described in which user plane communication and control plane communication for a particular mobile communication device can be split between a base station that operates a small cell and a macro base station. Appropriate security for the user plane and control plane communications is safeguarded by ensuring that each base station is able to obtain or derive the correct security parameters for protecting the user plane or control plane communication for which it is responsible.

## Claims

### Claim at position 1

1-48. (canceled)

### Claim 49

A base station (eNB) comprising:
a processor; and
a transceiver;
wherein the processor is configured to provide user plane communication to a user equipment (UE);
wherein the transceiver is configured:
to receive, from another base station, a security key, wherein the received security key is a key that is derived by the another eNB using a further security key, and wherein the further security key is key that is derived by a mobility management entity (MME) using an intermediate key;
wherein the processor is further configured to derive a user plane security key, for use in protection of user plane traffic, using the security key derived by the another eNB; and
wherein the another eNB provides control plane signalling to the mobile communication device.

### Claim 50

A method in a base station (eNB) comprising:
providing user plane communication to a user equipment (UE);
receiving, from another eNB, a security key, wherein the received security key is a key that is derived by the another eNB using a further security key, and wherein the further security key is key that is derived by a mobility management entity (MME) based on an intermediate key; and
deriving a user plane security key, for use in protection of user plane traffic, using the security key derived by the another base eNB;
wherein the another eNB provides control plane signalling to the eNB.

### Claim 51

User equipment comprising:
a processor; and
a transceiver;
wherein the transceiver is configured:
to receive control plane signalling from a first base station (eNB); and
to receive user plane signalling from a second eNB;
wherein the processor is configured:
to derive a security key of the first eNB, wherein the security key of the first eNB is a key that is derived by the UE based on an intermediate key;
to derive, using the derived security key of the eNB, a security key of the second eNB; and
to derive, using the security key of the second eNB, a user plane security key for use in protection of user plane traffic.

### Claim 52

A method performed by user equipment, the method comprising:
receiving control plane signalling from a first base station (eNB) and user plane signalling from a second eNB;
deriving a security key of the first eNB, wherein the security key of the first eNB is a key that is derived by the UE based on an intermediate key;
deriving, using the derived security key of the first eNB, a security key of the second eNB; and
deriving, using the security key of the second eNB, a user plane security key for use in protection of user plane traffic.

### Claim 53 (depends on 49)

A base station (eNB) according to claim 49, wherein the user plane security key is a KUPenc security key.

### Claim 54 (depends on 49)

A base station (eNB) according to claim 49, wherein the security key derived by the another eNB is a KeNB security key of the eNB and wherein the further security key from which the KeNB security key of the eNB is derived is a KeNB of the another eNB that is derived by the MME using the intermediate key as an input to an appropriate key derivation function (KDF).

### Claim 55 (depends on 49)

A base station (eNB) according to claim 49, wherein the intermediate key is a KASME key.

### Claim 56 (depends on 55)

A base station (eNB) according to claim 55, wherein KASME key is a key that is derived using a cipher key (CK), an integrity key (IK) and a serving network identity (SN id).

### Claim 57 (depends on 51)

A user equipment according to claim 51, wherein the user plane security key is a KUPenc security key.

### Claim 58 (depends on 51)

A user equipment according to claim 51, wherein the security key of the first eNB is a first KeNB security key and the security key of the second eNB is a second KeNB that is derived using the first KeNB as an input to an appropriate key derivation function (KDF).

### Claim 59 (depends on 58)

A user equipment according to claim 58, wherein the KeNB security key of the first eNB is derived using the intermediate key as an input to an appropriate key derivation function (KDF).

### Claim 60 (depends on 51)

A user equipment according to claim 51, wherein the intermediate key is a KASME key.

### Claim 61 (depends on 59)

A user equipment according to claim 59, wherein KASME key is a key that is derived from a cipher key (CK), an integrity key (IK) and a serving network identity (SN id).