WO2021232435A1

WO2021232435A1 - Method and apparatus for use in a communication system involving a radio interface between a user equipment and another user equipment associated with a radio access network

Info

Publication number: WO2021232435A1
Application number: PCT/CN2020/091922
Authority: WO
Inventors: György WOLFNER; Ling Yu; Vinh Van Phan; Xiang Xu; Laurent Thiebaut
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2021-11-25
Also published as: CN115669073A

Abstract

An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment,; and sending to the core network for the second user equipment at least some of the content of the message.

Description

METHOD AND APPARATUS FOR USE IN A COMMUNICATION SYSTEM INVOLVING A RADIO INTERFACE BETWEEN A USER EQUIPMENT AND ANOTHER USER EQUIPMENT ASSOCIATED WITH A RADIO ACCESS NETWORK

TECHNICAL FIELD

The present disclosure relates to an apparatus, a method, and a computer program and in particular but not exclusively for an apparatus, methods and computer programs for use in a system involving a radio interface between a user equipment and another user equipment associated with a radio access network.

BACKGROUND

A communication system may involve a user equipment sending and/or receiving data and/or control signalling to a core network via a radio interface with another user equipment served by a radio access network.

SUMMARY

An apparatus comprising: means for preparing a message at a first user equipment, and means for transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

The message may comprise at least content that is transparent to at least the core network for the second user equipment.

The message may comprise at least a Layer 2 message, for example a Access-Stratum (AS) message, and the content addressed to the core network for the first user equipment comprises at least Layer 3 content, for example, a Non-Access Stratum (NAS) message..

An apparatus comprising: means for receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and means for sending to the core network for the second user equipment at least some of the content of the message.

The content sent to the core network for the second user equipment may comprise at least content transparent to at least the core network for the first user equipment.

The content sent to the core network for the second user equipment may comprise a Layer 2 message, for example, a Access-Stratum (AS) message, comprising at least Layer 3 content, for example, a Non-Access Stratum (NAS) message.

The content sent to the core network for the second user equipment may comprise an Ethernet packet data unit.

Apparatus comprising: means for receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and means for forwarding the message onto a radio access network for the first user equipment.

The message may comprise an Ethernet packet data unit.

Apparatus comprising: means for receiving a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment; and means for recovering data and/or signalling from the message.

The message may include at least content transparent to at least the core network for the second user equipment.

The message may comprise a Layer 2 message, for example, an Access-Stratum (AS) message, comprising Layer 3 content, for example, a Non-Access-Stratum (NAS) message.

The message may comprise an Ethernet packet data unit.

Apparatus comprising: means for preparing a message for a first user equipment at a core network for the first user equipment, and means for sending the message to a core network for a second user equipment, wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

The message may comprise at least a Layer 2 message, for example, an Access-Stratum (AS) message, comprising at least Layer 3 content, for example, a Non-Access Stratum (NAS) message.

The message may comprise an Ethernet packet data unit.

Apparatus comprising: means for preparing a message at a first equipment; and means for transmitting the message over a radio interface between the first user equipment and a second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

Apparatus comprising: means for receiving via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and means for selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: preparing a message at a first user equipment, and transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

The message may comprise at least a Layer 2 message, for example, an Access-Stratum (AS) message, and the content addressed to the core network for the first user equipment comprises at least Layer 3 content, for example, a Non-Access Stratum (NAS) message.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and sending to the core network for the second user equipment at least some of the content of the message.

The content sent to the core network for the second user equipment may comprise a Layer 2 message, for example, an Access-Stratum (AS) message, comprising at least Layer 3 content, for example, a Non-Access Stratum (NAS) message.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and forwarding the message onto a radio access network for the first user equipment.

The message may comprise an Ethernet packet data unit.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment; and recovering data and/or signalling from the message.

The message may comprise a Layer 2 message, for example, an Access-Stratum (AS) message, comprising Layer 3 content, for example, a Non-Access Stratum (NAS) message.

The message may comprise an Ethernet packet data unit.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: preparing a message for a first user equipment at a core network for the first user equipment, and sending the message to a core network for a second user equipment, wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

The message may comprise an Ethernet packet data unit.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: preparing a message at a first equipment; and transmitting the message over a radio interface between the first user equipment and a second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

A method comprising: preparing a message at a first user equipment, and transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

The message may comprise at least a Layer 2 message, for example, an Access Stratum (AS) message, and the content addressed to the core network for the first user equipment comprises at least Layer 3 content, for example, a Non-Access Stratum (NAS) message.

A method comprising: receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment; and sending to the core network for the second user equipment at least some of the content of the message.

The content sent to the core network for the second user equipment may comprise a Layer 2 message, for example an Access-Stratum (AS) message, comprising at least Layer 3 content, for example, a Non-Access Stratum (NAS) message.

A method comprising: receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and forwarding the message onto a radio access network for the first user equipment.

The message may comprise an Ethernet packet data unit.

A method comprising: receiving a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment; and recovering data and/or signalling from the message.

The message may comprise an Ethernet packet data unit.

A method comprising: preparing a message for a first user equipment at a core network for the first user equipment, and sending the message to a core network for a second user equipment, wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

The message may comprise an Ethernet packet data unit.

A method comprising: preparing a message at a first equipment; and transmitting the message over a radio interface between the first user equipment and a second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

A method comprising: receiving via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

A computer readable medium comprising program instructions stored thereon for performing: preparing a message at a first user equipment, and transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

A computer readable medium comprising program instructions stored thereon for performing: receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and sending to the core network for the second user equipment at least some of the content of the message.

A computer readable medium comprising program instructions stored thereon for performing: receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and forwarding the message onto a radio access network for the first user equipment.

A computer readable medium comprising program instructions stored thereon for performing: receiving a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment; and recovering data and/or signalling from the message.

A computer readable medium comprising program instructions stored thereon for performing: preparing a message for a first user equipment at a core network for the first user equipment, and sending the message to a core network for a second user equipment, wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

A computer readable medium comprising program instructions stored thereon for performing: preparing a message at a first equipment; and transmitting the message over a radio interface between the first user equipment and a second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

A computer readable medium comprising program instructions stored thereon for performing: receiving via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: preparing a message at a first user equipment, and transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: : receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and sending to the core network for the second user equipment at least some of the content of the message.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: : receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and forwarding the message onto a radio access network for the first user equipment.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: receiving a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment; and recovering data and/or signalling from the message.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: preparing a message for a first user equipment at a core network for the first user equipment, and sending the message to a core network for a second user equipment, wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: preparing a message at a first equipment; and transmitting the message over a radio interface between the first user equipment and a second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

A non-transitory computer readable medium comprising program instructions stored thereon for performing: receiving via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: prepare a message at a first user equipment, and transmit the message over a radio interface between the first user equipment and a second user equipment , wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment; and send to the core network for the second user equipment at least some of the content of the message.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment ; and forward the message onto a radio access network for the first user equipment.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment ; and recover data and/or signalling from the message.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: prepare a message for a first user equipment at a core network for the first user equipment, and send the message to a core network for a second user equipment , wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: prepare a message at a first equipment ; and transmit the message over a radio interface between the first user equipment and a second user equipment ; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and select a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

A non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods.

An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: preparing a message at a first user equipment , and transmitting the message over a radio interface between the first user equipment and a second user equipment , wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.

An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment , ; and sending to the core network for the second user equipment at least some of the content of the message.

Apparatus comprising: receiving circuitry for receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment ; and forwarding circuitry for forwarding the message onto a radio access network for the first user equipment.

Apparatus comprising: receiving circuitry for receiving a message at a core network for a first user equipment via at least a core network for a second user equipment and a radio interface between the first user equipment and the second user equipment ; and recovering circuitry for recovering data and/or signalling from the message.

Apparatus comprising: preparing circuitry for preparing a message for a first user equipment at a core network for the first user equipment, and sending circuitry for sending the message to a core network for a second user equipment , wherein the first user equipment is connected to the core network for the first user equipment via the core network for the second user equipment and a radio interface between the first and second user equipments.

Apparatus comprising: preparing circuitry for preparing a message at a first equipment; and transmitting circuitry for transmitting the message over a radio interface between the first user equipment and a second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.

Apparatus comprising: receiving circuitry for receiving via at least a radio interface between a first user equipment and a second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and selecting circuitry for selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.

In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above.

Various other aspects are also described in the following detailed description and in the attached claims.

BRIEF DESCRIPTION OF THE FIGURES

Some example embodiments will now be described in further detail, by way of example only, with reference to the following examples and accompanying drawings, in which:

Figure 1 shows a representation of a system architecture according to some example embodiments;

Figure 2 shows a representation of user plane and control plane protocol stacks according to some example embodiments;

Figure 3 shows a representation of procedures according to some example embodiments;

Figures 4a to 4g show methods according to some example embodiments;

Figure 5 shows a representation of a system architecture according to some example embodiments;

Figure 6 shows a representation of user plane and control plane protocol stacks according to some example embodiments;

Figure 7 shows a representation of procedures according to some example embodiments;

Figure 8 shows a representation of a control apparatus according to some example embodiments;

Figure 9 shows a representation of an apparatus according to some example embodiments; and

Figure 10 shows a representation of non-volatile memory media according to some example embodiments.

DETAILED DESCRIPTION

With reference to Figures 1 and 2, according to some example embodiments, one user equipment (remote UE 102) does not have its own radio interface to a radio access network, and relies on a radio interface between the Remote UE 102 and another user equipment (relay UE 104) , and a radio interface between the relay UE 104 and a radio access network 106.

According to some example embodiments, relay 104 uses Layer 2 connectivity (e.g. an Ethernet PDU (packet data unit) session) to forward all user plane and control plane traffic for the remote UE 102 to/from the remote UE 102.

According to some example embodiments, there is a core network (5G-CN Remote 118) for the remote UE that is separate and independent to the core network (5G-CN Relay 116) for the relay UE 104. The core network 116 for the relay UE comprises a collection of inter-operating core network entities including an access mobility function entity (AMF) 110, a session management function (SMF) entity (not shown) and a user plane function entity (UPF) 108. The core network 118 for the remote UE 102 also comprises a separate collection of inter-operating core network entities including an access mobility function entity (AMF) 114, a session management function (SMF) entity (not shown) and a user plane function entity (UPF) 112.

According to some example embodiments, there is an N1 interface between the remote UE 102 and the core network 118 for the remote UE. This N1 interface allows Layer 3 content for example, the Non-Access Stratum (NAS) messages, to be kept transparent to e.g. relay UE core network 116 via which the content is transferred between the remote UE 102 and the core network 118 for the remote UE 102.

In Figure 1, box 120 represents the Layer 2 Ethernet PDU session via which Layer 3 content for example, the Non-Access Stratum (NAS) messages, is transferred between the remote UE 102 and the core network 118 for the remote UE 102.

According to some example embodiments, a normal IP-type PDU session is used instead of a Ethernet-type PDU session for relayed traffic between Relay UE 102 and UPF-Relay 110: According to this alternative, Relay-UE 104 performs IP routing/NATting; UPF Relay 110 performs IP routing; Remote UE 102 is assigned a local IP address; non-access stratum (NAS) for Remote UE 102 is over IP.

A remote UE attachment procedure according to some example embodiments is shown in Figure 3.

Operation 1) : Relay UE 104 creates an PDU session for Remote UE 102 with PDU type Ethernet according to 3GPP TS 23.502.

Operation 2) a PC5 interface is created between Remote UE 102 and Relay UE 104, and the core network 116 for the Relay UE 104 assigns an AMF for the Remote UE 102: The Remote UE 102 provides information that is needed for selecting an AMF for the Remote UE 102 selection to the Relay UE 104 via the PC5 interface (radio interface) between the Remote UE 102 and the Relay UE. One example of such information is e.g. Slice information, Globally Unique Temporary ID (GUTI) ; Relay UE 104 forwards this information received from Remote UE 102 to the core network for the Relay UE 104 via a radio interface between the Relay UE 104 and the radio access network (e.g. 5G base station –GnB) , which enables the selection of a “Remote AMF” for the Remote UE 102 by the core network 116 for the Relay UE 104.. An entity in the core network 116 for the Relay UE 104 (e.g. a policy charging function entity) selects an AMF for the Remote UE 102, and the core network 116 for the Relay UE 104 provides the Ethernet MAC address of the AMF selected for the Remote UE 102 to the Relay UE 104; and the Relay UE 104 forwards this information to the Remote UE 102.

Operation 2b) : The UPF 108 for the Relay UE 104 configures a forwarding rule for the traffic between the Remote UE 102 and the AMF Remote 118. Other examples use simple Ethernet bridging without this forwarding rule.

Operation 3) Remote UE 102 uses NAS over Ethernet (via PC5 interface (radio interface) between the Remote UE 102 and the Relay UE 104, and via the PDU session for the Relay UE 104, to communicate with AMF 114 selected for the Remote UE 102 in the previous operation to register (this includes the authentication of the Remote UE 102) and then to create PDU sessions for data traffic for the Remote UE 102. From the perspective of the Relay UE 104, RAN 106 and Relay CN 116, this user data is user data (secured with NAS security) to be forwarded. The AMF 114 for the Remote UE 102 performs AMF tasks for the Remote UE 102 (including e.g. authentication, IP address assignment) and configures forwarding rules in the UPF for the Relay UE 104 for PDU sessions for the Remote UE 102. Other examples use simple Ethernet bridging without these forwarding rules.

Operation 4) : data sessions for the Remote UE are forwarded via the PC5 interface (radio interface between the Remote UE 102 and the Relay 104) , and via L2 PDU bearers for the Relay UE 104. The UPF 108 for the Relay UE 104 and the Relay UE 104 may perform some mapping of the QoS flows.

According to one alternative example, Operation 2) involves a radio access network entity (e.g. 5G gNB) 106 making the selection of an AMF for the Remote UE 102. The radio access network entity 106 makes this selection without storing the Relay UE context in the radio access network entity 106. The UPF 108 for the Relay UE 104 is typically close to the gNB 106, and when the Remote UE 102 switches from a PC5 interface (radio interface with Relay UE 104) to a Uu interface (radio interface with a radio access network node (gNB) the gNB to which the Remote UE 102 switches is not far from the gNB 106 continuing to serve the Relay UE 104, and thus the gNB 106 for the Relay UE 104 is able to select an appropriate AMF for the Remote UE 102.

If the Relay UE 104 enters Idle/Inactive mode, the Relay UE 104 can be paged when there is downlink traffic for the Remote UE 102.

In the event of a loss of Uu or PC5 connection, the AMF 110 for the Relay UE 104 notifies the AMF 114 for the Remote UE 102.

Mobility of the Remote UE 102 is supported because the remote UE 102 is assigned to core network entities (AMF, SMF, UPF) 112, 114 that are independent from

core network entities

108, 110 assigned to the Relay UE 104, and these independent

core network entities

112, 114 assigned to the Remote UE serve as anchor points during mobility between direct network connection (Uu radio interface between Remote UE 102 and RAN 106) and relayed connection (via PC5 radio interface between Remote UE 102 and Relay UE 104, and Uu radio interface between Relay UE 102 and RAN 106) . This also enables the Relay-UE 104 to support Remote-UE 102 using different core networks, e.g. due to the different Home Public Land Mobile Network (HPLMN) of the Remote-UE 102.

Security against e.g. the core network 116 for the Relay UE 104 monitoring the content of messages for the Remote UE 102 is good because the Remote UE 102 performs a authentication with the network over NAS, and the signaling between the Remote UE 102 and the core network 118 for the Remote UE 102 is protected by NAS security. Control plane (NAS) connection (including authentication, mobility and session management) between the Remote UE 102 and the core network 118 for the Remote UE 102 is independent to the control plane connection between the Relay UE 104 and the core network 116 for the Relay UE 104.

As Ethernet type connection is used, the Relay UE 104 can avoid assigning a local IPv4 address or IPv6 prefix to the Remote UE 102, by performing Ethernet bridging instead of IP routing and NATting.

The control and user plane traffic of the Remote UE 102 are forwarded as user plane traffic of the Relay UE 104 over an Ethernet (layer 2) type of PDU session of the Relay UE 104 in a transparent way.

Reference is made to Figure 4a, which shows uplink operation of Remote UE 102 according to some example embodiments.

At step 400, the operation may comprise: preparing a message at the Remote UE 102.

At step 402, the operation may comprise: transmitting the message over a radio interface between the Remote UE 102 and Relay UE 104, wherein the message comprises at least content addressed to a core network 118 for the Remote UE and wherein the core network for the Remote UE is independent to a core network for the Relay UE.

According to some example embodiments, the message comprises at least content that is transparent to at least the core network for the Relay UE 104.

According to some example embodiments, the message comprises at least a Layer 2 message, for example, a Access-Stratum (AS) message, , and the content addressed to the core network 118 for the Remote UE 102 comprises at least Layer 3 content, for example, the Non-Access-Stratum (NAS) message.

Reference is made to Figure 4b, which shows uplink operation of a core network 116 for Relay UE 104 according to some example embodiments.

At step 404, the operation may comprise: receiving a message at a core network 116 for a Relay UE via at least a radio interface between the Relay UE 104 and the Remote UE 102..

At step 406, the operation may comprise sending to the core network 118 for the Remote UE 102 at least some of the content of the message.

According to some example embodiments, the content sent to the core network 118 for the Remote UE 102 comprises at least content transparent to at least the core network 116 for the Relay UE 104.

According to some example embodiments, the content sent to the core network 118 for the Remote UE 102 comprises a Layer 2 message for example, a Access-Stratum (AS) message, comprising at least Layer 3 content, for example, the Non-Access-Stratum (NAS) message.

According to some example embodiments, the content sent to the core network 118 for the Remote UE 102 comprises an Ethernet packet data unit.

Reference is made to Figure 4c, which shows downlink operation of a core network 116 for Relay UE 104 according to some example embodiments.

At step 408, the operation may comprise: receiving a message at a core network 116 for Relay UE 104 from a core network 118 for Remote UE 102, wherein the Remote UE 102 is connected to the core network 116 for Relay UE 104 via at least a radio interface between the Relay UE 104 and the Remote UE 102.

At step 410, the operation may comprise: forwarding the message onto the radio access network 106 for the Relay UE 104.

According to some example embodiments, the message comprises an Ethernet packet data unit.

Reference is made to Figure 4d, which shows uplink operation of a core network 118 for Remote UE 102 according to some example embodiments.

At step 412, the operation may comprise: receiving a message at a core network 118 for Remote UE 102 via at least a core network 116 for Relay UE 104 and a radio interface between the Remote UE 102 and the Relay UE 104.

At step 414, the operation may comprise recovering data and/or signalling from the message.

According to some example embodiments, the message includes at least content transparent to at least the core network 116 for the Relay UE.

According to some example embodiments, the message comprises a Layer 2 message, for example, a Access-Stratum (AS) message comprising Layer 3 content for example, the Non-Access-Stratum (NAS) message.

Reference is made to Figure 4e, which shows downlink operation of a core network 118 for Remote 102 according to some example embodiments.

At step 416, the operation may comprise: preparing a message for Remote UE 102 at a core network 118 for the Remote UE 102.

At step 418, the operation may comprise: sending the message to the core network 116 for Relay UE 104, wherein the Remote UE 102 is connected to the core network 118 for the Remote UE 102 via the core network 116 for the Relay UE 104 and a radio interface between Remote UE 102 and Relay 104.

According to some example embodiments, the message comprises at least content that is transparent to at least the core network 116 for the Relay UE 104.

According to some example embodiments, the message comprises at least a Layer 2 message, for example, a Access-Stratum (AS) message, comprising at least Layer 3 content, for example, the Non-Access-Stratum (NAS) message.

Reference is made to Figure 4f, which shows operation of Remote UE 102 according to some example embodiments.

At step 420, the operation may comprise preparing a message at Remote UE 102.

At step 422, the operation may comprise transmitting the message over a radio interface between the Remote UE 102 and Relay UE 104, wherein the message includes information for selecting a mobility management function entity for the remote UE 102.

Reference is made to Figure 4g, which shows operation of the core network 116 for Relay UE 104 according to some example embodiments.

At step 424, the operation may comprise receiving via at least the core network 116 for Relay UE 104 and a radio interface between the Remote UE and Relay UE a message including information for selecting a mobility management function entity for Remote UE 102.

At step 426, the operation may comprise: selecting a mobility management function entity for the Remote UE 102, wherein the mobility management function for Remote UE 102 is independent to a mobility management function for Relay UE 104.

According to some example embodiments, a ProSe 5G UE-to-Network Relay entity 102 (Relay UE) provides the functionality to support connectivity to the network for Remote UEs (see Figure 5) for both public safety services and commercial services (e.g. interactive service) . A Remote UE 102 successfully establishes a PC5 link to a Relay UE 104. A Remote UE 102 can be inside NG-RAN coverage or outside of NG-RAN coverage.

Some example embodiments, provide traffic confidentiality (e.g. when not provided by higher /Application layers) , and IP @ preservation at mobility between direct 5GC access (via Uu connected to NG RAN) and 5GC access via a Relay UE 104.

Some example embodiments reuse the Untrusted access to a 5G core network (5GC) that may be reused for 5G core network (5GC) access to a Public Land Mobile Network (PLMN) via a Stand-Alone Non-Public Network (SNPN) entity and a Non-3GPP Interworking Function (N3IWF) entity. According to some example embodiments, the N3IWF entity treats 5G Prose Remote UE 102 in the same way as a non-3GPP (N3GPP) UE.

Figure 6 shows a representation of a protocol stack of ProSe 5G UE-to-Network Relay with support of N3IWF, according to some example embodiments.

Some example embodiments involve handling of IP version 4. The Relay UE 104 allocates an IP @ to the Remote UE 102; The Relay UE 104 enforces NAPT (Network Address and Port Translation) between PC5 and Uu. For downlink (DL) traffic it uses the port above IP to determine the PC5 address and link (remote UE 102) to use. The Relay UE 104 is unaware of whether it relays UP or CP for the Remote UE 102.

Some example embodiments involve handling of IP Version 6. The Relay UE 104 provides an IP Prefix to the Remote UE 102; the Relay UE 104 may use PD (Prefix Delegation to get prefixes to allocate to Remote UE (s) 102. The Relay UE 104 acts as a Requesting Router.

According to some example embodiments, the core network 116 to which the Relay UE 104 is registered and the core network 118 to which the Remote UE 102 is registered correspond to the same PLMN.

According to some example embodiments, the core network 116 to which the Relay UE 104 is registered and the core network 118 to which the Remote UE 102 is registered correspond to different PLMNs.

According to some example embodiments, the RAN transparency of the remote UE for the RAN 106 ensures: confidentiality of data traffic of the remote UE 102 without eavesdropping by the Relay UE 104., and/or possibility for IP address preservation for remote UE 102 when it moves between (i) PC5 access via Relay UE 104 and (ii) native direct Uu access to the 5G system (5GS) without relaying.

According to some example embodiments, the operation is transparent for NG RAN 106. The NG RAN (gNB) 106 and the UPF 108 for the Relay UE 104 are not aware of the relay operation for remote UE 102.

Figure 7 shows a representation of the connection of 102 Remote UE via a Relay UE 104, according to some example embodiments.

Operation 0: The Relay UE 104 and Remote UE 102 are provisioned for UE-to-NW relaying including provisioning for baseline PC5 usage and for relaying operation. The provisioned information may include at least the information of the N3IWF, the policy to use the N3IWF, the security parameter, etc .

Operation 1: The Relay UE 104 registers with the 5G Core Network, which may follow the registration procedure as specified in TS23.502.

Operation 2: The Remote UE 102 discovers and selects Relay UE 104 and establishes a connection for One-to-one ProSe Direct Communication.

Operation 3: The Remote UE 102 requests for ProSe 5G UE-to-Network Relay operation. A procedure for authorization of relaying may take place.

Operation 4: In the event that the 5G Relay UE 104 hasn no PDU session that can support the requirements of the PC5 connection with the remote UE 102, including suitable Single -Network Slice Selection Assistance Information (S-NSSAI) , Data Network Name (DNN) and Quality of Service (QoS) parameters, the Relay UE 104 initiates a PDU session establishment for relaying traffic of the Remote UE 102. The trigger to establish this dedicated PDU Session could be the first PC5 set-up request from a Remote UE 102. The PDU session release criteria may be the release of the last PC5 for the remote UE 102.

Operation 5: IPv6 prefix is allocated for the remote UE and/or IPv4 address is allocated. Uplink and downlink data relaying can start after this step. The Remote UE 102 gets a local IP address from the Relay UE 104 following the L3 procedure, where the Relay UE 104 acts as a Dynamic Host Configuration Protocol (DHCP) server (or Stateless Autoconfiguration (SLAAC) Router or Router with Prefix Delegation for IPv6) and NAPT. The Relay UE 104 may enforce NAPT between PC5 and Uu. For DL traffic the Relay UE 104 uses the Transmission Control Protocol/User Datagram Protocol. (TCP/UDP) port to determine the PC5 address and link (remote UE 102) to use. The Relay UE 104 holds a mapping table between local IP addresses and PC5 links as the relay UE 104 may act as a relay for multiple Remote UEs 102.

From here onwards, remote UE signalling procedures towards its N3IWF are run over the PDU session established by the Relay UE 104 in operation 4 and using IP address information negotiated in operation 5.

Operation 6: The Remote UE 102 determines whether it needs the services of a N3IWF. This decision can be UE implementation dependent or controlled by local policies that may take into account application level ciphering mechanisms and Application level IP mobility requirements , and/or by operator policy configured in the Remote UE, and/or by the information or indication received from the Relay UE 104.

Operation 7a: the Remote UE 102 discovers N3IWF using DNS lookup , or using the configured N3IWF information.

Operation 7b: the Remote UE 102 connects to N3IWF selected in operation 7a for Internet Key Exchange (IKE) establishment.

Operation 7c: the Remote UE 102 registers to the core network (5GC) via the selected N3IWF. The N3IWK considers this Remote UE access as N3GPP access. Thus, the remote UE is authenticated via its own credentials.

Operation 8: The Remote UE 102 establishes data connectivity over the registered N3IWF access. The Remote UE 102 may set up one or multiple PDU Sessions or move existing PDU Sessions as follows. The Remote UE 102 can establish one or more new PDU Sessions. Based on mobility of a PDU Session that the Remote UE 102 was using before using relaying, the Remote UE 102 can proceed following PDU Session mobility procedures. The Remote UE registers via N3IWF and establishes PDU Session. According to some example embodiments, IPsec is used for both NAS and UP traffic of the Remote UE 102, and both NAS and UP traffic of the Remote UE 102 are hidden from the Relay UE 104.

IKE keep alive (s) between the Remote UE 102 and the N3IWF 122 may be used for detecting possible path failure.

Mobility of a Remote UE 102 between different Relay UE (s) may be supported when the Remote UE 102 and N3IWF 122 support IKEv2 Mobility and Multihoming Protocol (MOBIKE) . This is negotiated between the Remote UE 102 and the N3IWF 122.

Figure 8 illustrates an example of a control apparatus 900 for use at any of the entities of the RAN 106 and

core networks

116, 118, such as the

AMF entities

110, 114 and

UPF entities

108, 112.. The control apparatus may comprise at least one random access memory (RAM) 911a, at least on read only memory (ROM) 911b, at least one

processor

912, 913 and an input/output interface 914. The at least one

processor

912, 913 may be coupled to the RAM 911a and the ROM 911b. The at least one

processor

912, 913 may be configured to execute an appropriate software code 915. The software code 915 may for example allow to perform one or more steps to perform one or more of the operations described above The software code 915 may be stored in the ROM 911b. The control apparatus 900 at one of the above-mentioned entities may be interconnected with another control apparatus 900 at one or more other of the above-mentioned entities.

Figure 9 illustrates an example of a user equipment or terminal 1000, such as a user equipment described previously. The terminal 1000 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’ , a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle) , a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (IoT) type communication device or any combinations of these or the like. The terminal 1000 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email) , text message, multimedia, data, machine data and so on.

The terminal 1000 may receive signals over an air or radio interface 1007 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 10 transceiver apparatus is designated schematically by block 1006. The transceiver apparatus 1006 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

The terminal 1000 may be provided with at least one processor 1001, at least one memory ROM 1002a, at least one RAM 1002b and other possible components 1003 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 1001 is coupled to the RAM 1011a and the ROM 1011b. The at least one processor 1001 may be configured to execute an appropriate software code 1008. The software code 1008 may for example allow to perform one or more of the present aspects. The software code 1008 may be stored in the ROM 1011b.

The processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 1004. The device may optionally have a user interface such as key pad 1005, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

Figure 10 shows a schematic representation of non-volatile memory media 1100a (e.g. computer disc (CD) or digital versatile disc (DVD) ) and 1100b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 1102 which when executed by a processor allow the processor to perform one or more of the steps of the methods described previously.

It is to be noted that embodiments of the present invention may be implemented as circuitry, in software, hardware, application logic or a combination of software, hardware and application logic. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer or smart phone, or user equipment.

As used in this application, the term "circuitry" refers to all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware) , such as (as applicable) : (i) to a combination of processor (s) or (ii) to portions of processor (s) /software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor (s) or a portion of a microprocessor (s) , that require software or firmware for operation, even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

The described features, advantages, and characteristics of the invention can be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages can be recognized in certain embodiments that may not be present in all embodiments of the invention. One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.

Claims

An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the at least one memory and

computer program code configured to, with the at least one processor, cause the apparatus to perform:

preparing a message at a first user equipment, and transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.
The apparatus according to claim 1, wherein the message comprises at least content that is transparent to at least the core network for the second user equipment.
The apparatus according to claim 1 or claim 2, wherein the message comprises at least a Layer 2 message, and the content addressed to the core network for the first user equipment comprises at least Layer 3 content.
An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform:

receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and sending to the core network for the second user equipment at least some of the content of the message.
The apparatus according to claim 4, wherein the content sent to the core network for the second user equipment comprises at least content transparent to at least the core network for the first user equipment.
The apparatus according to claim 4 or claim 5, wherein the content sent to the core network for the second user equipment comprises at least Layer 3 content.
The apparatus according to claim 4 or claim 5, wherein the content sent to the core network for the second user equipment comprises an Ethernet packet data unit.
An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform:

receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and

forwarding the message onto a radio access network for the first user equipment.
The apparatus according to claim 8, wherein the message comprises an Ethernet packet data unit.
The apparatus according to claim 1, wherein the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus to perform: preparing a message at the first equipment; and transmitting the message over the radio interface between the first user equipment and the second user equipment; wherein the message includes information for selecting a mobility management function entity for the first user equipment.
The apparatus according to claim 4, wherein the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving via at least the radio interface between the first user equipment and the second user equipment a message including information for selecting a mobility management function entity for the second user equipment; and selecting a mobility management function entity for the second user equipment, wherein the mobility management function for the second user equipment is independent to a mobility management function for the first user equipment.
A method comprising:

preparing a message at a first user equipment, and

transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.
A method comprising:

receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and

sending to the core network for the second user equipment at least some of the content of the message.
A method comprising:

receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and

forwarding the message onto a radio access network for the first user equipment.
A computer readable medium comprising program instructions stored thereon for performing: :

preparing a message at a first user equipment, and

transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.
A computer readable medium comprising program instructions stored thereon for performing:

receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and

sending to the core network for the second user equipment at least some of the content of the message.
A computer readable medium comprising program instructions stored thereon for performing:

receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and

forwarding the message onto a radio access network for the first user equipment.
An apparatus comprising: means for preparing a message at a first user equipment, and means for transmitting the message over a radio interface between the first user equipment and a second user equipment, wherein the message comprises at least content addressed to a core network for the first user equipment, and wherein the core network for the first user equipment is independent to a core network for the second user equipment.
An apparatus, comprising:

means for receiving a message at a core network for a first user equipment via at least a radio interface between the first user equipment and a second user equipment, ; and means for sending to the core network for the second user equipment at least some of the content of the message.
An apparatus, comprising:

means for receiving a message at a core network for a first user equipment from a core network for a second user equipment, wherein the second user equipment is connected to the core network for the first equipment via at least a radio interface between the first user equipment and the second user equipment; and

means for forwarding the message onto a radio access network for the first user equipment.