Patent Description:
Telecommunication networks enable User Equipments, UEs, to communicate with each other via one of a number of access nodes and via one or more core networks. Typically, the UE's are mobile terminals designed to be used by human users, such as mobile smart phones, tablets, Virtual Reality, VR, headsets, or anything alike. The term UE may also refer to equipment designed to be used in a Machine-to-Machine or Internet of Things context, such as devices, wearables, sensors, actuators, cameras, cars, media devices, or anything alike. The term UE may also refer to generally stationary communication devices, such as fixed phones, computers, or stationary Internet of Things, IOT, devices, smart meters or anything alike. In the following description the term User Equipment is used, which is intended to cover any of the above identified use cases.

In the context of the present disclosure, a telecommunication network comprises the access network, for example the evolved UMTS Terrestrial Radio Access, E-UTRAN, access network as well as the core network, for example the Evolved Packet Core, EPC, network. The access node is typically the node in the access network to which a UE directly communicates, for example the Evolved Node B, the radio base station or anything alike.

The last couple of years, proximity-based services, ProSe, have been introduced in the telecommunication network for providing additional functionality for a UE. The features of ProSe include ProSe discovery and ProSe Direct Communication.

A ProSe capable UE may perform a ProSe discovery to identify ProSe-enabled UEs in its proximity. Direct Communication enables the establishment of a direct communication connection between ProSe-enabled UEs that are in direct communication range. The ProSe Direct Communication path could use different radio technologies, for example, E-UTRAN or Wireless Local Area Network, WLAN, or anything alike.

ProSe Direct communication also facilitates the use of a ProSe UE-to-Network relay, which acts as a relay between the access network and a remote UE. The ProSe UE-to-Network relay entity thus provides the functionality to support connectivity to the telecommunication network for remote UE's. A UE is considered to be a remote UE for a certain ProSe UE-to-Network relay if it has successfully established a direct communication path to the UE-to-Network relay. A remote UE can be located within, or outside, the coverage area of the access node.

The ProSe UE-to-Network Relay relays unicast traffic, uplink as well as downlink, between the Remote UE and the telecommunication network. The ProSe UE-to-Network Relay provides generic functions that can relay any Internet Protocol, IP, traffic. Here, ProSe Direct Communication is used between Remote UEs and the ProSe UE-to-Network Relays for the unicast traffic.

<CIT> describes a system in which a UE-Relay receives, from a user communication device, a message requesting the provision of a communication link (e.g. a Layer <NUM> link) between the user communication device and a network serving the user communication device. The UE-Relay communicates with its core network, responsive to the received message, to establish the communication link from the user communication device to a base station remote from the UE-Relay; and relays data, between the user communication device and the base station using the communication link.

<CIT> discloses a wireless terminal provided with: a control unit that executes a process for establishing a relay connection with a network using a Device to Device (D2D) proximity service; a transmission unit that transmits a discovery message for relay after the connection has been established; and a reception unit that receives a request message from another wireless terminal that has received the discovery message. The request message contains the identifier of the other wireless terminal. The control device executes control for sending the identifier, as an identifier of a remote node through which data can be relayed by relay, of the other wireless terminal to a network device included in an Evolved Packet Core (EPC).

<CIT> describes procedures for dynamically activating and deactivating proximity services (ProSe) enabled WTRU-to-Network (NW) relays and control plane procedures to establish a link between remote WTRUs and WTRU-NW relays.

<NPL> describes two alternatives to sharing a PDN connection between UE-R and P-GW with multiple UE-os (i.e. out of coverage UEs) connected to UE-R (i.e. UE-to-Network Relay), wherein the first alternative is L2 ProSe UE-to-Network Relay with Bearer sharing, and the second alternative is a L2 ProSe UE-to-Network Relay with Network Attach.

One of the drawbacks of the above identified known methods of relaying traffic by the UE-to-Network relay is that the network is not able to determine whether traffic is related to the UE-to-Network Relay or related to the remote UE using the UE-to-Network Relay for its connection to the telecommunication network.

It is an objective to provide for methods of establishing a connection between a remote User Equipment, UE, and a telecommunication network via a relay capable UE and for distinguishing between traffic with the remote UE and traffic with the relay capable UE when the remote UE uses the relay capable UE as a relay to the core network.

It is another objective to provide for systems for supporting establishment of a connection between a remote User Equipment, UE, and a telecommunication network via a relay capable UE and for distinguishing between traffic with the remote UE and traffic with the relay capable UE when the remote UE uses the relay capable UE as a relay to the core network.

According to the invention, in a first aspect there is provided a method comprising:.

Preferably, said command is also directed to the establishment of the second UE-to-access node bearer.

According to the presented method, the access node is able to distinguish between traffic associated with said relay capable UE via said Radio Access Bearer and traffic associated with said remote UE over said Remote Radio Access Bearer. That is, the traffic from the remote UE and the traffic from the relay capable UE are carried over different connections.

One of the advantages of the presented method for the access node is that the access node is able to use conventional mobility management procedures for, e.g., performing handovers. Another advantage is that the Remote Radio Access Bearer may have its own encryption and security context. For the remote UE, it will look like a conventional security context. The telecommunication network may see two different security contexts, one for the remote UE and one for the relay capable UE.

Another advantage of the above is that the access node as well as the core network have separate representations for the remote UE and the relay capable UE, respectively, as well as their state. This means that there is a separate connection for each of the UEs, i.e. the remote UE and the relay capable UE, to the telecommunication network. As such, the relaying is performed in such a way that the access node and the core network are able to distinguish the traffic associated with the relay capable UE from the traffic associated with the remote UE, and are able to manage the connections thereof separately. This includes, for example, standard mobility and session management procedures.

One of the advantages of the presented method for the core network is that the core network can perform Quality-of-Service, QoS, control and charging for each of the UE's separately.

According to the present disclosure, said remote UE is directly made visible to the access node by introducing the second UE-to-access node bearer, which is established between the relay capable UE and the access node. The relay capable UE may thus act as a relay of signalling and user plane traffic between the remote UE and the radio access network, i.e. the access node.

It is noted that, typically, each of the nodes involved in the establishing process may store information required to forward traffic in both directions. This information may, for example, be an identification of the UE-to-UE bearer, the second UE-to-access node bearer, the access node-to-core network bearer and/or an identification of the remote UE and the relay capable UE.

The Remote Radio Access Bearer between the remote UE, i.e. the first end point, and the core network, i.e. the second end point, actually comprises three bearers associated to each other. These three bearers constitute the UE-to-UE bearer established between the remote UE and the relay capable UE, the second UE-to-access node bearer established between the relay capable UE and the access node, and finally the access node-to-core network bearer established between the access node and the core network. Identifications of these three bearers in relation to the Remote Radio Access Bearer may be stored in intermediate nodes in order for the intermediate nodes to be able to associate these three bearers with the Remote Radio Access Bearer. For example, the relay capable UE may store identifications of the UE-to-UE bearer as well as the second UE-to-access node bearer. The access node may store identifications of the second UE-to-access node bearer as well as the access node-to-core network bearer.

In an embodiment, the Request Relay message comprises an identifier for identifying said remote UE at the access node, wherein said method further comprises the steps of:.

The above described embodiment is directed to the scenario that the remote UE, initially, has a direct, i.e. non-relayed connection to the core network. That is, the remote UE may be connected to the core network in a conventional manner by, for example, an established Radio Access Bearer between itself and the core network.

After a while, the remote UE may decide that it would be beneficial to have a relayed connection to the core network. Such a decision may, for example, be based on a non-reliable non-relayed connection, or the desire to save battery power by using a nearby device as relay. As such, using a relayed connection, the remote UE may be connected to the core network in a more stable, reliable and more battery power efficient manner.

In order to discover a relay capable UE, the remote UE may perform a ProSe discovery method as described in, for example, TS <NUM>, chapter <NUM> ProSe Direct Discovery. The result of such a discovery method is finding a relay capable UE that may act as a relay for the remote UE towards the telecommunication network.

In accordance with the above described embodiment, the same access node is used for both the connection of the relay capable UE to the network and the direct, i.e. non-relayed, connection of the remote UE to the network. As such, it is preferred that a non-relayed connection to the core network of the remote UE is already established via that same access node. To determine whether the non-relayed connection of the remote UE to the core network is established via the access node, an identifier may be provided in the Request Relay message for identifying the remote UE at the access node. The identifier is, for example, a Cell Radio Network Temporary Identifier, or other similar identifier that identifies the UE at the access node. The access node may thus be able to determine whether it already has a connection to the remote UE using the identifier in the Request Relay message.

Finally, once the bearers for the Remote Radio Access Bearer have been established between the remote UE and the relay capable UE, between the relay capable UE and the access node, and between the access node and the core network, the non-relayed connection between the remote UE and the core network may be released, i.e. the underlying bearers for the RAB may be released. This action may be performed upon receipt of an acknowledgement message from the relay capable UE indicating that the requested bearers between the remote UE and the relay capable UE and between the relay capable UE and the access node are established and/or upon receipt of an acknowledgement message from the core network that a new access node to core network node bearer has been established, or upon receipt of both acknowledgement messages. It might also be possible that one of the bearers of the RAB is re-used and not released.

Following the above, initially, a Radio Access Bearer was established between the remote UE and the core network. This Radio Access Bearer comprised a UE-to-access node bearer and an access node-to-core network bearer. This Radio Access Bearer becomes the Remote Radio Access Bearer once the decision has been made, for example by the remote UE, to start relaying via the relay capable UE. In this particular case a new UE-to-UE bearer, i.e. between the remote UE and the relay capable UE may be added to the already existing Radio Access Bearer, and a new UE-to-access node bearer, i.e. between the relay capable UE and the access node, may be established. These different bearers may all be associated with the Remote Radio Access Bearer that does not change its identification. The core network does not necessarily need to know that anything has changed, it may still see the same Radio Access Bearer. So, the nodes in the core network would not necessarily see the difference between the original Radio Access Bearer and the Remote Radio Access Bearer.

The above described embodiment is, for example, an embodiment directed to a remote UE being in EPS Connection Management, ECM, connected mode.

In a further embodiment, the step of receiving the Request Relay message further comprises:.

This above described embodiment is directed, for example, to the situation in which the remote UE is in ECM-idle mode. In this particular case, a service request, for example a Non-Access Stratum, NAS, service request, is received for requesting services from the telecommunication network. The request is forwarded to a Mobility Management network function, for example a Mobility Management Entity, MME, comprised by the telecommunication network. Typically, a Mobility Management Entity sends an initial Context Setup Request to the access node in reply to the received service request.

The advantage of the above described embodiment is that the remote UE can be connected to the telecommunication network via the relay capable UE, even in the situation when the remote UE does not have a separate, non-relayed connection established to the telecommunication network. From the perspective of the core network, the remote UE may be connected in the same way as a UE that is connected directly, i.e. non-relayed.

In a further embodiment, the method comprises the step of:.

Preferably, said acknowledgement message comprises an indication that said second UE-to-access node bearer has also been established.

The advantage of this embodiment is that the access node is made aware of the fact that the UE-to-UE bearer and the second UE-to-access node bearer have been established.

In yet another embodiment, the access node is a base station in a cellular network, for example an evolved node B, eNB.

The expressions, i.e. the wording, of the different aspects comprised by the method and devices according to the present disclosure should not be taken literally. The wording of the aspects is merely chosen to accurately express the rationale behind the actual functioning of the aspects.

In accordance with the present disclosure, different aspects applicable to the above mentioned examples of the methods in a first aspect of the invention, including the advantages thereof, correspond to the aspects which are applicable to methods of the second aspect or the third aspect of the invention.

In a second aspect, the invention provides for a non-transitory computer-readable storage medium, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any of the embodiments as described above.

Any type of computer readable storage medium may be utilized. The computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory, RAM, a read-only memory, ROM, an erasable programmable read-only memory, a portable compact disc read-only memory, an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

In a third aspect, the invention provides for an access node arranged for establishing a connection between a remote User Equipment, UE, and a telecommunication network via a relay capable UE, wherein said telecommunication network comprises a core network and an access network, said access network comprising an access node, wherein said relay capable UE has an established Radio Access Bearer between said relay capable UE and said core network wherein said established Radio Access Bearer comprises:.

said access node is further arranged for distinguishing between traffic with said relay capable UE over said first UE-to-access node bearer and traffic with said remote UE over said second UE-to-access node bearer based on information stored during establishment of the Remote Radio Access Bearer when said remote UE uses said relay capable UE as a relay to said core network.

The above-mentioned and other features and advantages of the disclosure will be best understood from the following description referring to the attached drawings. In the drawings, like reference numerals denote identical parts or parts performing an identical or comparable function or operation. In the following description only the subject-matter of <FIG> or <FIG> and their descriptions, both in combination with the subject-matter of <FIG> and its description, is according to the invention as defined in the claims. The rest of the following description and figures (even if named embodiment(s)) does not or does not fully correspond to the invention as defined in the claims and is therefore not according to the invention as defined in the claims but is considered as useful for understanding the invention.

<FIG> shows a schematic illustration <NUM> of an established Remote Radio Access Bearer <NUM> between the remote User Equipment, UE, <NUM> and the core network as indicated with reference numeral <NUM>. In a more specific example, e.g. in an LTE network, the Remote Radio Access Bearer <NUM> is established between the remote UE <NUM> and any of a Mobility Management Function, such as a Mobility Management Entity, MME, or a gateway function, such as the serving gateway, SGW.

The core network <NUM> could be the Evolved Packet Core, EPC. In such a case, the SGW anchors user-plane mobility in a SGW serving area and functions as a termination point of the packet data network interface towards the access network, i.e. the access node <NUM>. The MME is involved in the bearer activation and deactivation process and is responsible for choosing the SGW for the remote UE <NUM> at the initial attach thereof to the network. Further, the MME is responsible for authenticating the remote UE <NUM>, for example by interacting with the Home Subscriber Server, HSS. The Non Access Stratum, NAS, signalling terminates at the MME and it is also responsible for generation and allocation of temporary identities to UE's.

The schematic illustration <NUM> of <FIG> shows that the Remote Radio Access Bearer <NUM> is established via the relay capable UE <NUM> and the access node <NUM>. The access node <NUM> is, for example, a base station in a cellular network. More specifically, the access node <NUM> may be an Evolved Node B, eNB in an LTE network or a NodeB in an UMTS network. In case of a centralized Radio Access Network an access node <NUM> may be a combination of a radio function unit, referred to as Remote Radio Head, and a processor function, referred to as the Base Band Unit. Other splits of functionality of an access node may also be possible.

The Remote Radio Access Bearer <NUM> is considered a logical bearer established between the remote UE <NUM> and the core network <NUM>. The Remote Radio Access Bearer <NUM> actually comprises three separate bearers.

A first of these three bearers is indicated with reference numeral <NUM>. This bearer is a UE-to-UE bearer <NUM> and is established between the remote UE <NUM> and the relay capable UE <NUM>. Such a bearer is thus established to support device to device communication, or ProSe communication. In the 3GPP architecture for LTE, the UE-to-UE bearer <NUM> would be considered to be established over the PC5 interface.

A second of these three bearers is indicated with reference numeral <NUM> and is referenced to as the second UE-to-access node bearer <NUM>. This bearer may be a radio bearer <NUM> and is established between the relay capable UE <NUM> and the access node <NUM>. This radio bearer <NUM> is intended to carry traffic to, and from, the remote UE <NUM> only. In the 3GPP architecture for LTE, the UE-to-access node bearer <NUM> would be considered to be established over the Uu interface.

A third of these three bearers is indicated with reference numeral <NUM> and is referenced to as an access node-to-core network bearer <NUM>. This bearer is established between the access node <NUM> and the core network <NUM>. In the 3GPP architecture for LTE, the access node-to-core network bearer <NUM> would be considered to be established over the S1 interface.

It is noted that for the ProSe communication, two different scenario's may exist, i.e. an "in coverage" scenario and a "partial coverage" scenario. In an "in coverage" scenario, the remote UE <NUM> as well as the relay capable UE <NUM> are within coverage range of the access node <NUM>, and the network may control the resources used for ProSe communication.

In a partial coverage situation such a centralized control may not be feasible. That is, the remote UE <NUM> is not in direct coverage of the access node <NUM> and the relay capable UE <NUM> is in direct coverage of the access node <NUM>.

The schematic illustration <NUM> of <FIG> further shows an established Radio Access Bearer <NUM> between the relay capable UE <NUM> and the core network <NUM>. This specific Radio Access Bearer <NUM> is a dedicated bearer for the relay capable UE <NUM>. As such, this bearer is not used for communication to, and from, the remote UE <NUM>. The Radio Access Bearer <NUM> comprises two separate bearers which are associated to the Radio Access Bearer <NUM>.

The first bearer is referenced to as a first UE-to-access node bearer <NUM> and is established between the relay capable UE <NUM> and the access node <NUM>. The second bearer is referenced to as an access node-to-core network bearer <NUM> and is established between the access node <NUM> and the core network <NUM>.

It is noted that the solution of introducing a Remote Radio Access Bearer <NUM> makes the remote UE <NUM> directly visible to the access network <NUM> and core network <NUM>, while the remote UE <NUM> is being relayed via the relay capable UE <NUM>. The relay capable UE <NUM> will then act as a relay of signalling and user plane traffic between the remote UE <NUM> and the access node <NUM>.

The Remote Radio Access Bearer <NUM> represents the connection of the remote UE <NUM> to the core network <NUM> and may be used for data transfer. Each of the nodes over which the Remote Radio Access Bearer <NUM> is established may store information required to forward the traffic in both directions. This type of information may be the bearer or connection identifications used to create associations which a node accesses to find where to forward packets belonging to the Remote Radio Access Bearer <NUM>. These associations may be saved during the establishment of the Remote Radio Access Bearer <NUM>.

Following the above, the access node <NUM> is thus able to distinguish between traffic with said relay capable UE <NUM> over said first UE-to-access node bearer <NUM> and traffic with said remote UE over said second UE-to-access node bearer <NUM>.

<FIG> shows a signalling diagram <NUM> in which a UE-to-UE bearer as well as a second UE-to-access node bearer is established for a remote UE in connected mode.

Here below, an explanation of the signalling diagram <NUM> is provided with references to the ECM-Connected state as known in the Long Term Evolution, LTE, network. A similar, or the same, state is however also known in other networks, making the signalling diagram <NUM> also applicable to these types of networks.

In the signalling diagram <NUM>, the remote UE is indicated with reference numeral <NUM>, the relay capable UE is indicated with reference numeral <NUM>, the access node is indicated with reference numeral <NUM>, the core network is indicated with reference numeral <NUM> and the ProSe Function is indicated with reference numeral <NUM>.

Here, reference numeral <NUM> indicates that the remote UE <NUM> has already attached a non-relayed, direct connection to the core network <NUM>. As such, the remote UE <NUM> is within the coverage area of the access node <NUM>. The remote UE <NUM> has thus connected to the network in a standard, conventional manner.

The remote UE <NUM> may decide that it would like a relayed connection towards the network. In order to discover potential UEs that could serve as a relay for the remote UE <NUM>, the remote UE <NUM> may initiate a proximity-based applications and services, ProSe, discovery process <NUM>.

A ProSe discovery process <NUM> is a process that identifies a UE that is ProSe-enabled in the proximity of another, using evolved UMTS Terrestrial Radio Access, E-UTRA or the evolved packet core, EPC. The depicted ProSe discovery process <NUM> may result in the discovery of the relay capable UE <NUM>, i.e. a UE that is capable to act as a relay for the remote UE <NUM>.

Following the discovery of the relay capable UE <NUM>, the remote UE <NUM> sends <NUM> a Request Relay message to the discovered relay capable UE <NUM> via a PC5 connection. The message is a request from the remote UE <NUM> for using the relay capable UE <NUM> as a relay to the core network <NUM>. This Request Relay message may include an identifier, for example the temporary Cell Radio Network Temporary Identifier, C-RNTI, for identifying said remote UE <NUM> at the access node <NUM>. The message may further comprise information with respect to Quality-of-Service, QoS, requirements that the remote UE <NUM> needs or already has on existing Radio Bearers.

The relay capable UE <NUM> may perform checks <NUM>, i.e. processing constraints, QoS parameters, allowed UE's to be relayed, etc., whether to authorize the relaying of the remote UE <NUM>. In case of a positive outcome, the relay capable UE <NUM> sends <NUM> the Request Relay message towards the access node <NUM>. In another embodiment, the relay capable UE <NUM> sends <NUM> the Request Relay message towards the access node <NUM> without performing checks <NUM>.

The access node <NUM> will then find, if available, the connection <NUM> it already has to the remote UE <NUM> based on the identifier, i.e. the temporary Cell Radio Network Temporary Identifier, present in the Request Relay message. Not according to the invention as claimed, if it is determined <NUM> that the initial connection <NUM> of the remote UE <NUM> to the core network <NUM> is not established via the same access node <NUM> as the connection of the relay capable UE <NUM> to the core network <NUM>, a Request Relay Complete message is sent <NUM>, <NUM> from the access node <NUM>, via the relay capable UE <NUM> to the remote UE <NUM>. This message indicates that relay is currently not possible. An alternative to sending the Request Relay Complete message is to perform a handover such that the remote UE is serviced by the same access node as the relay capable UE. The block indicated with reference numeral <NUM> depicts the situation that the remote UE <NUM> is to release its connection <NUM> to the core network <NUM>, and is to initiate the start of the relaying process from the ECM-Idle state as will be elucidated with respect to <FIG>.

On the determination that the initial connection <NUM> of the remote UE <NUM> to the core network <NUM> is established via the same access node <NUM> as the connection of the relay capable UE <NUM> to the core network <NUM>, the access node <NUM> sends <NUM> a command for establishing the UE-to-UE bearer and the second UE-to-access node bearer. This command is, for example, coupled to an RRC Radio Bearer Setup procedure message having embedded therein an PC5 bearer setup flag.

The relay capable UE <NUM> receives the command and uses, for example, PC5 signalling <NUM> to invoke a UE-to-UE bearer setup between the remote UE <NUM> and the relay capable UE <NUM>, for example the PC5 bearer setup.

When the relay capable UE <NUM> has received <NUM> a confirmation to the PC5 bearer setup from the remote UE <NUM>, and the second UE-to-access node bearer has been established between the relay capable UE <NUM> and the access node, the relay capable UE <NUM> may acknowledge <NUM> the establishment of both bearers to the access node <NUM>. The relay capable UE <NUM> may further save <NUM> any information necessary to relay Packet Data Convergence Protocol, PDCP, data between the remote UE <NUM> and the access node <NUM>.

Once the UE-to-UE bearer has been established and once the second UE-to-access node bearer has been established, the access node <NUM> may store <NUM> the information related to the underlying bearers of the Remote Radio Access Bearer, i.e. the established UE-to-UE bearer, the established UE-to-access node bearer and an access node-to-core network bearer. The access node-to-core network bearer may be the same bearer as was previously used for the connection of the remote UE to the network or it may also be a different bearer. Typically, such a bearer is the S1 bearer.

Finally, the access node <NUM> sends <NUM> a Request Relay Complete message to the relay capable UE <NUM>, which, in turn, sends <NUM> this message to the remote UE <NUM> indicating that the Remote Radio Access Bearer has been established. Further, the access node <NUM> may send a command <NUM> to the remote UE <NUM> to release its initial connection <NUM> to the core network. Alternatively, the access node <NUM> could release the connection <NUM> by itself and acknowledge this to the remote UE. The procedure is then completed by the remote UE <NUM> updating its tracking area <NUM> to the core network <NUM>, using a Non Access Stratum, NAS, connection.

<FIG> shows a signalling diagram <NUM> in which a UE-to-UE bearer as well as a second UE-to-access node bearer is established for a remote UE in idle mode. In this respect, the remote UE is indicated with reference numeral <NUM>, the relay capable UE is indicated with reference numeral <NUM>, the access node is indicated with reference numeral <NUM>, the core network is indicated with reference numeral <NUM> and the ProSe function is indicated with reference numeral <NUM>.

The signalling diagram <NUM> depicted in <FIG> discloses the situation in which the remote UE <NUM> does not have a Radio Access Bearer established to the core network <NUM>, or in the situation that the remote UE <NUM> has lost its connection, but is still known in the network. In these kinds of situations, the procedure is supplemented with an additional service request message which will be explained in more detail here below.

In a first step, the remote UE <NUM> attaches <NUM> to the core network <NUM> in a conventional manner. Second, the remote UE <NUM> performs a ProSe discovery process <NUM> to determine whether there are UE's in its proximity that could serve as a relay for a connection to the core network <NUM>. These two steps are also explained with reference to <FIG> and will not be explained here in more detail.

Different from the scenario in <FIG> is that here, the remote UE is in idle mode <NUM>, which is for example indicated with the ECM-IDLE state in a Long Term Evolution, LTE, network.

Again, the remote UE <NUM> sends <NUM> a Request Relay message towards the relay capable UE <NUM> for using the relay capable UE <NUM> as a relay to the core network <NUM>. Here, the Request Relay message also comprises a Service Request for requesting services from the telecommunication network. The service request may, alternatively, also be sent in a separate message. Such a service request is, for example, an LTE Service Request message directed to the MME.

The relay capable UE <NUM> then may again perform checks <NUM> to determine whether it can serve as a relay for the remote UE <NUM>, and, if approved, it forwards <NUM> the Request Relay message, comprising the service request, to the access node <NUM>. In an alternative embodiment, the relay capable UE <NUM> sends <NUM> the Request Relay message towards the access node <NUM> without performing checks <NUM>.

Upon receipt of the Request Relay message, the access node <NUM> forwards <NUM> the service request to the core network <NUM>, and receives <NUM> a context setup procedure from the core network <NUM>, for example from the Mobility Management Entity.

Most of the remainder steps depicted in <FIG> are the same as the steps depicted in <FIG> and are therefore not explained in detail. That is, step <NUM> corresponds to step <NUM>, step <NUM> corresponds to step <NUM>, step <NUM> corresponds to step <NUM>, step <NUM> corresponds to step <NUM>, step <NUM> corresponds to step <NUM>, step <NUM> corresponds to <NUM>, step <NUM> corresponds to step <NUM>, step <NUM> corresponds to step <NUM> and step <NUM> corresponds to step <NUM>. In addition to the above, the access node <NUM> confirms <NUM> to the core network <NUM> that the context setup procedure is completed.

<FIG> shows a signalling diagram <NUM> in which the relaying for the remote UE is stopped.

Here, the remote UE is indicated with reference numeral <NUM>, the relay capable UE is indicated with reference numeral <NUM>, the access node is indicated with reference numeral <NUM> and the core network is indicated with reference numeral <NUM>.

In this situation a Remote Radio Access Bearer <NUM> is established between the remote UE <NUM> and the core network <NUM> via the relay capable UE <NUM> and the access node <NUM>.

The remote UE <NUM> decides to cancel the relaying of traffic via the relay capable UE <NUM> (e.g. because the remote UE <NUM> notices that the connection with the relay capable UE <NUM> is deteriorating) and sends <NUM> a Request Relay Cancel message to the access node <NUM> via, for example, Access Stratum signalling.

The access node <NUM> is able to determine <NUM> that the connection from the remote UE <NUM> is being relayed via the relay capable UE <NUM> using an identification of the remote UE <NUM> or a direct identification of the UE-to-UE bearer established between the remote UE <NUM> and the relay capable UE <NUM>. Alternatively, the Request Relay Cancel message sent <NUM> comprises an identification of the Remote Radio Access Bearer for which relaying needs to be cancelled. In this case, the access node <NUM> may have the context information stored to determine that this particular Radio Access Bearer is in fact a Remote Radio Access Bearer. A Radio Bearer Setup message is then sent <NUM> by the access node <NUM> to the remote UE <NUM> to initiate the establishment of a radio bearer directly between the remote UE <NUM> and the access node <NUM>. This new radio bearer is not to be established via the relay capable UE <NUM>.

The remote UE <NUM> then confirms <NUM> the establishment of the Radio Bearer, and the remote UE <NUM> starts using <NUM> the bearer for, for example, uplink data. Then, the access node <NUM> confirms <NUM> cancelling of the relay, changes <NUM> the specific Remote Radio Access Bearer into a normal Radio Access Bearer <NUM> and starts using <NUM> the direct radio bearer to the remote UE <NUM> for downlink traffic.

Upon completion of the relay cancelling, the access node <NUM> orders the relay capable UE <NUM> to release all relay resources by sending <NUM>, <NUM> a Radio Bearer Release message comprising a UE-to-UE bearer release Flag. This triggers the release procedure to the remote UE <NUM>, and is acknowledged, by the remote UE <NUM>, in an acknowledgement message <NUM>, <NUM> towards the access node <NUM>.

If in an alternative case the UE-to-UE connection is broken, a timeout mechanism may be used to release the resources in the remote UE.

Finally, the access node removes <NUM> all information with respect to the relaying connection of the remote UE <NUM> to the core network <NUM> and the remote UE <NUM> updates <NUM> its tracking area to the core network <NUM>.

<FIG> shows a signalling diagram <NUM> in which the remote UE switches from an idle mode to a connected mode during relaying by the relay capable UE.

In this situation, the remote UE <NUM> may use the relay capable UE <NUM> as a relay and its connectivity states are the same as when its connection to the network is direct, i.e. not relayed. Moving from an idle state to a connected state may then be performed as shown in <FIG>. That is, a service request message, for example an NAS service request message, is sent <NUM> over the UE-to-UE signalling connection to the relay capable UE <NUM>, which relay capable UE <NUM>, in turn, forwards <NUM> that request to the access node <NUM>, which access node <NUM>, in turn, forwards <NUM> the request to the core network <NUM>.

A confirmation is sent <NUM>, <NUM>, <NUM> by the core network <NUM> and is forwarded by each of the intermediate nodes <NUM>, <NUM> to the remote UE <NUM>, wherein the confirmation comprises an UE-to-UE bearer setup flag for indicating that the UE-to-UE bearer should be established.

The remote UE <NUM> then sends <NUM> a confirmation to the relay capable UE <NUM> that the UE-to-UE bearer is established, and the relay capable UE <NUM> stores <NUM> any information related to the relayed connection. An identification of the UE-to-UE bearer is then sent <NUM> to the access node, and the access node saves <NUM> any information, i.e. information related to the Remote Radio Access Bearer, with respect to the remote UE <NUM> as a relayed connection from the remote UE <NUM> to the core network <NUM> via the relay capable UE <NUM>. Finally, a confirmation is sent <NUM> to the core network for indicating that the bearers have been established.

<FIG> shows an example of a control plane stack <NUM> between the remote UE, the relay capable UE, the access node as well as the core network.

Here, the remote UE is indicated with reference numeral <NUM>, the relay capable UE is indicated with reference numeral <NUM>, the access node is indicated with reference numeral <NUM> and the core network, more specifically the MME, is indicated with reference numeral <NUM>.

In this respect it is noted that the remote UE <NUM> is arranged for establishing a connection between a remote UE and a telecommunication network via the relay capable UE <NUM>. The remote UE comprises a transmitter arranged for sending to the relay capable UE <NUM>, a Request Relay message, wherein the Request Relay message comprises a request for using the relay capable UE <NUM> as a relay to the core network.

The request is associated with establishment of a Remote Radio Access Bearer, wherein said Remote Radio Access Bearer comprises a UE-to-UE bearer between said remote UE and said relay capable UE, a second UE-to-access node bearer between said relay capable UE and said access node, wherein said second UE-to-access node bearer is different from said first UE-to-access node bearer, and an access node-to-core network bearer between said access node and said core network.

The remote UE <NUM> further comprises a processor arranged for establishing said UE-to-UE signalling connection, and for establishing a Non-Access Stratum, NAS, connection <NUM> between said remote UE and said core network over said established UE-to-UE signalling connection. Preferably, the NAS connection <NUM> is established over the PC5 signalling connection.

A single processor or other unit may fulfil the functions of several items recited in the claims.

Claim 1:
A method comprising:
- establishing a connection between a remote User Equipment, UE, and a telecommunication network via a relay capable UE, wherein said telecommunication network comprises a core network and an access network, said access network comprising an access node, wherein said relay capable UE has an established Radio Access Bearer between said relay capable UE and said core network wherein said established Radio Access Bearer comprises:
- a first UE-to-access node bearer between said relay capable UE and said access node, and
- an access node-to-core network bearer between said access node and said core network;
said method comprising the steps of:
- receiving a Request Relay message, from said relay capable UE, comprising a request, originating from said remote UE, for using said relay capable UE as a relay to the core network, wherein said request is associated with establishment of a Remote Radio Access Bearer, wherein said Remote Radio Access Bearer comprises:
- a UE-to-UE bearer between said remote UE and said relay capable UE;
- a second UE-to-access node bearer between said relay capable UE and said access node, wherein said second UE-to-access node bearer is different from said first UE-to-access node bearer, and
- an access node-to-core network bearer between said access node and said core network;
- sending to said relay capable UE, a command for establishing at least said UE-to-UE bearer,
and
- distinguishing between traffic with said relay capable UE over said first UE-to-access node bearer and traffic with said remote UE over said second UE-to-access node bearer based on information stored during establishment of the Remote Radio Access Bearer when said remote UE uses said relay capable UE as a relay to said core network.