Emergency call session establishment via a relay communication device

Abstract

A proxy server (22) in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20) is disclosed. The proxy server (22) receives a session establishment request (30) from a remote communication device (14) requesting establishment of an emergency call session. The session establishment request (30) indicates the session establishment request (30) was relayed via communication device relaying. The proxy server (22) obtains an identity (12-ID) of a relay communication device (12) that relayed the session establishment request (30). The proxy server (22) modifies the session establishment request (30) to include an access network information header field (34M) that indicates the identity (12-ID) of the relay communication device (12). The proxy server (22) forwards the modified session establishment request (30M) to another server (24) in the IMS network (20).

Description

[0001] EMERGENCY CALL SESSION ESTABLISHMENT VIA A RELAY COMMUNICATION DEVICE

[0002] RELATED APPLICATIONS

[0003] This application claims the benefit of provisional patent application serial number I N202411005175, filed on 2024-01-25, the disclosure of which is hereby incorporated herein by reference in its entirety.

[0004] TECHNICAL FIELD

[0005] The present application relates generally to emergency call session establishment in an Internet Protocol, IP, Multimedia Subsystem, IMS, network, and relates more particularly to emergency call session establishment via a relay communication device.

[0006] BACKGROUND

[0007] Proximity services (ProSe) in a communication network enable communication devices that are in proximity of one another to communicate directly, via a path not traversing any network node of the communication network. Proximity services relaying exploits ProSe so that one communication device can relay traffic for another communication device in proximity. A relay communication device in this regard is a communication device that communicates directly with a remote communication device in proximity, in order to relay traffic for the remote communication device to and / or from the communication network. Via the relay communication device, then, the remote communication device can communicate with the network even if the remote communication device is outside of the network’s coverage.

[0008] Proximity services relaying proves particularly promising for providing emergency service to a remote communication device, e.g., to ensure access to emergency service even outside of the network’s coverage. However, to do so requires connecting the remote communication device to an appropriate Public Safety Answering Point (PSAP) that is near the remote communication device’s location and / or providing that PSAP with the remote communication device’s location. Especially if the remote communication device is outside of network coverage, it may not be possible to determine the location of the remote communication device reliably. Because the relay communication device is in proximity to the remote communication device, the location of the relay communication device could approximate the location of the remote communication device, in which case the PSAP could be selected using the relay communication device’s location and / or the PSAP provided with the relay communication device’s location in lieu of the remote communication device’s location. Problematically, though, challenges exist in signaling information about the relay communication device in this and other scenarios, especially in a way that conforms to existing signaling paradigms.

[0009] SUMMARY

[0010] Some embodiments herein exploit an access network information header field of a session establishment request for signaling information about a relay communication device that relays communication for a remote communication device to and / or from a communication network. The session establishment request may for example indicate an identity of the relay communication device in the access network information header field, e.g., a P-Access-Network-Info header field of a Session Initiation Protocol (SIP) INVITE request. Signaling information about the relay communication device in this way facilitates validation of the relay communication device’s location, while advantageously conforming to existing signaling paradigms. As applied to an emergency call session, some embodiments herein may thereby improve the accuracy with which a communication network selects an appropriate Public Safety Answering Point (PSAP) to handle an emergency call session that is relayed by the relay communication device.

[0011] More particularly, embodiments herein include a method performed by a proxy server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. The method comprises receiving a session establishment request from a remote communication device requesting establishment of an emergency call session. The session establishment request indicates the session establishment request was relayed via communication device relaying. The method also comprises obtaining an identity of a relay communication device that relayed the session establishment request. The method also comprises modifying the session establishment request to include an access network information header field that indicates the identity of the relay communication device. The method also comprises forwarding the modified session establishment request to another server in the IMS network.

[0012] In some embodiments, the session establishment request is a Session Initiation Protocol, SIP, INVITE request.

[0013] In some embodiments, the proxy server implements a Proxy Call Session Control Function, P-CSCF.

[0014] In some embodiments, the access network information header field is a P-Access- Network- Info header field.

[0015] In some embodiments, the relay communication device is a 5G Proximity Services, ProSe, user equipment to network, U2N, relay, and the access network information header field includes a U2N-relay-ID parameter whose value is set to the identity of the relay communication device.

[0016] In some embodiments, the identity of the relay communication device is a core network level identity available for an Internet Protocol, IP, Connectivity Access Network, CAN, session within which the session establishment request is received. In some embodiments, the identity of the relay communication device is a subscription permanent identifier, SlIPI. In other embodiments, the identity of the relay communication device is a subscription concealed identifier, SlICI. In yet other embodiments, the identity of the relay communication device is an International Mobile Subscription Identifier, IMSI. In still yet other embodiments, the identity of the relay communication device is a Mobile Station International Subscriber Directory Number, MSISDN.

[0017] In some embodiments, the access network information header field further indicates that the identity of the relay communication device is provided by the IMS network.

[0018] In some embodiments, the modified session establishment request is forwarded to a server that implements an emergency Call Session Control Function, E-CSCF.

[0019] In some embodiments, the access network information header field further indicates that the session establishment request was relayed via communication device relaying. In other embodiments, the access network information header field further indicates alternatively or additionally a location of the relay communication device as provided by the remote communication device. In some embodiments, the access network information header field includes an access type parameter whose value indicates that the session establishment request was relayed via communication device relaying. In other embodiments, the access network information header field alternatively or additionally includes a cell identity parameter whose value indicates the location of the relay communication device in terms of an identity of a cell in which the relay communication device is located.

[0020] In some embodiments, said obtaining comprises retrieving the identity of the relay communication device from a Policy Control Function, PCF.

[0021] In some embodiments, said obtaining and modifying is performed responsive to determining that the session establishment request was relayed via communication device relaying. In some embodiments, said obtaining and modifying is performed responsive to determining that the session establishment request as received indicates a location of the relay communication device as provided by the remote communication device.

[0022] In some embodiments, the session establishment request as received includes a preferred identity header field that indicates an identity of the remote communication device, and the session establishment request as modified further includes an asserted identity header field that indicates the identity of the remote communication device as indicated by the preferred identity header field.

[0023] In some embodiments, the relay communication device is a 5G Proximity Services, ProSe, UE-to-Network relay, and / or wherein the remote communication device is a 5G ProSe Remote UE.

[0024] Other embodiments herein include a method performed by a server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. The method comprises receiving, by the server, a session establishment request requesting establishment of an emergency call session for a remote communication device. The session establishment request indicates the session establishment request was relayed via communication device relaying and includes an access network information header field that indicates an identity of a relay communication device that relayed the session establishment request.

[0025] In some embodiments, the session establishment request is a Session Initiation Protocol, SIP, INVITE request.

[0026] In some embodiments, the access network information header field is a P-Access-Network- Info header field.

[0027] In some embodiments, the relay communication device is a 5G Proximity Services, ProSe, user equipment to network, U2N, relay, and the access network information header field includes a U2N-relay-ID parameter whose value is set to the identity of the relay communication device.

[0028] In some embodiments, the identity of the relay communication device is a core network level identity available for an Internet Protocol, IP, Connectivity Access Network, CAN, session within which the session establishment request is received.

[0029] In some embodiments, the identity of the relay communication device is a subscription permanent identifier, SlIPI. In other embodiments, the identity of the relay communication device is a subscription concealed identifier, SlICI. In yet other embodiments, the identity of the relay communication device is an International Mobile Subscription Identifier, IMSI. In still yet other embodiments, the identity of the relay communication device is a Mobile Station International Subscriber Directory Number, MSISDN.

[0030] In some embodiments, the access network information header field further indicates that the identity of the relay communication device is provided by the IMS network.

[0031] In some embodiments, the relay communication device provides communication device relaying via Layer 2 or Layer 3. In one such embodiment, the access network information header field indicates information about an access network providing Layer 2 or Layer 3 connectivity via which the IMS network was accessed and includes a relay ID parameter whose value is set to the identity of the relay communication device.

[0032] In some embodiments, the access network information header field further indicates that the session establishment request was relayed via communication device relaying. In other embodiments, the access network information header field further indicates alternatively or additionally a location of the relay communication device as provided by the remote communication device. In some embodiments, the access network information header field includes an access type parameter whose value indicates that the session establishment request was relayed via communication device relaying. In other embodiments, the access network information header field alternatively or additionally includes a cell identity parameter whose value indicates the location of the relay communication device in terms of an identity of a cell in which the relay communication device is located. In some embodiments, the session establishment request further includes an asserted identity header field that indicates the identity of the remote communication device.

[0033] In some embodiments, the relay communication device is a 5G Proximity Services, ProSe, UE-to-Network relay, and / or wherein the remote communication device is a 5G ProSe Remote UE.

[0034] In some embodiments, the session establishment request is received from a proxy server that implements a Proxy Call Session Control Function, P-CSCF. In some embodiments, the server implements an emergency Call Session Control Function, E-CSCF.

[0035] In some embodiments, the session establishment request indicates a location of the relay communication device as provided by the remote communication device, and the method further comprises transmitting, to a location server, a query to validate the location of the relay communication device as provided by the remote communication device. In some embodiments, the query includes the session establishment request. In some embodiments, the method further comprises receiving a response to the query. In some embodiments, the method further comprises routing the session establishment request based on the response. In some embodiments, the server implements an emergency Call Session Control Function, E-CSCF. In some embodiments, the response indicates an address of a selected Public Safety Answering Point, PSAP, for the emergency call session, and routing the session establishment request comprises routing the session establishment request towards the address of the selected PSAP.

[0036] In some embodiments, the session establishment request is received from an emergency Call Session Control Function, E-CSCF, and the server implements a location retrieval function, LRF.

[0037] In some embodiments, the session establishment request indicates a location of the relay communication device as provided by the remote communication device. In some embodiments, the session establishment request is received in a query to validate the location of the relay communication device as provided by the remote communication device. In some embodiments, the method further comprises validating the location of the relay communication device as provided by the remote communication device. In some embodiments, the validation comprises obtaining a location of the relay communication device identified by the identity. In some embodiments, the validation comprises comparing the obtained location to the location of the relay communication as provided by the remote communication device. In some embodiments, the method further comprises transmitting a response to the query based on said validating.

[0038] Other embodiments herein include a proxy server configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. The proxy server is configured to receive a session establishment request from a remote communication device requesting establishment of an emergency call session. The session establishment request indicates the session establishment request was relayed via communication device relaying. The proxy server is also configured to obtain an identity of a relay communication device that relayed the session establishment request. The proxy server is also configured to modify the session establishment request to include an access network information header field that indicates the identity of the relay communication device. The proxy server is also configured to forward the modified session establishment request to another server in the IMS network.

[0039] In some embodiments, the proxy server is configured to perform any of the steps described above for a proxy server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network.

[0040] Other embodiments herein include a server configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. The server is configured to receive a session establishment request requesting establishment of an emergency call session for a remote communication device. The session establishment request indicates the session establishment request was relayed via communication device relaying and includes an access network information header field that indicates an identity of a relay communication device that relayed the session establishment request.

[0041] In some embodiments, the server is configured to perform any of the steps described above for a server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network.

[0042] In some embodiments, a computer program comprising instructions which, when executed by at least one processor of a proxy server, causes the proxy server to perform the steps described above for a proxy server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. In some embodiments, a computer program comprising instructions which, when executed by at least one processor of a proxy server, causes the proxy server to perform the steps described above for a server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. In some embodiments, a carrier containing the computer program is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

[0043] Other embodiments herein include a proxy server configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. The proxy server comprises communication circuitry and processing circuitry. The processing circuitry is configured to receive a session establishment request from a remote communication device requesting establishment of an emergency call session. The session establishment request indicates the session establishment request was relayed via communication device relaying. The processing circuitry is also configured to obtain an identity of a relay communication device that relayed the session establishment request. The processing circuitry is also configured to modify the session establishment request to include an access network information header field that indicates the identity of the relay communication device. The processing circuitry is also configured to forward the modified session establishment request to another server in the IMS network.

[0044] In some embodiments, the processing circuitry is configured to perform any of the steps described above for a proxy server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. Other embodiments herein include a server configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network. The server comprises communication circuitry and processing circuitry. The processing circuitry is configured to receive a session establishment request requesting establishment of an emergency call session for a remote communication device. The session establishment request indicates the session establishment request was relayed via communication device relaying and includes an access network information header field that indicates an identity of a relay communication device that relayed the session establishment request.

[0045] In some embodiments, the processing circuitry is configured to perform any of the steps described above for a server in an Internet Protocol, IP, Multimedia Subsystem, IMS, network.

[0046] Embodiments herein also include corresponding apparatus, computer programs, and carriers of those computer programs.

[0047] Of course, the present disclosure is not limited to the above features and advantages. Indeed, those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a block diagram of an IMS network that includes a proxy server and a server for supporting communication device relaying of a session establishment request in accordance with some embodiments.

[0050] Figure 2 is a block diagram of an IMS network that includes a proxy server and a server for supporting communication device relaying of a session establishment request for an emergency call session in accordance with some embodiments.

[0051] Figure 3 is a call flow diagram for supporting communication device relaying of a session establishment request for an emergency call session in accordance with some embodiments.

[0052] Figure 4 is a logic flow diagram of a method performed by a proxy server in an IMS network according to some embodiments.

[0053] Figure 5 is a logic flow diagram of a method performed by a server in an IMS network according to some embodiments.

[0054] Figure 6 is a block diagram of a proxy server in an IMS network according to some embodiments.

[0055] Figure 7 is a block diagram of a server in an IMS network according to some embodiments.

[0056] Figure 8 is a block diagram of a communication system in accordance with some embodiments.

[0057] Figure 9 is a block diagram of a user equipment according to some embodiments.

[0058] Figure 10 is a block diagram of a network node according to some embodiments. Figure 11 is a block diagram of a host according to some embodiments.

[0059] Figure 12 is a block diagram of a virtualization environment according to some embodiments.

[0060] DETAILED DESCRIPTION

[0061] Figure 1 shows a communication network 10 (e.g., a 5G network) according to some embodiments. The communication network 10 provides communication service to communication devices, e.g., user equipments (UEs). The communication network 10 in this regard includes an Internet Protocol (IP) Multimedia Subsystem (IMS) network 20 that delivers multimedia services over IP network(s), e.g., to enable the deployment of voice, video, and / or data communication over an IP-based infrastructure.

[0062] The communication network 10 in particular is shown as providing communication service to communication device 12. Communication device 12 may for example access the communication network 10 via an access link 16, e.g., over an air interface. Communication device 12 in this regard is shown as being within coverage of the communication network 10.

[0063] Communication device 12 in the example of Figure 1 serves as a relay for another communication device 14 in proximity, e.g., which may or may not be within the coverage area of the communication network 10. Communication device 12 in this role relays communication for communication device 14 to and / or from the communication network 10, e.g., so as to operate as a device-to-network relay. As such, communication device 12 is referred to herein as the relay communication device 12 and communication device 14 is referred to as the remote communication device 14. To accomplish this relaying, the relay communication device 12 may communicate directly with the remote communication device 14, e.g., using Proximity Services (ProSe), via a path not traversing any network node of the communication network 10.

[0064] The relay communication device 12 may for example receive uplink traffic from the remote communication device 14 over a sidelink 18 (e.g., a PC5 interface) with the remote communication device 14 and correspondingly transmit that uplink traffic to the communication network 10 over its access link 16 to the communication network 10. Alternatively or additionally, the relay communication device 12 may receive downlink traffic from the communication network over its access link 16 with the communication network 10 and transmit that downlink traffic to the remote communication device 14 over the sidelink 18. Such relaying may for example occur at Layer 2 or Layer 3 of the devices’ protocol stack, in which case the relay communication device 12 may be a 5G Proximity Services (ProSe) Layer 2 (L2) or Layer 3 (L3) UE-to-network (U2N) relay (5G Prose L2 / L3 U2N relay) and the remote communication device 14 may be a 5G ProSe Remote UE. In any event, via the relay communication device 12, the remote communication device 14 can communicate with the communication network 10 even if the remote communication device 14 is outside of (i.e. , remote to) the network’s coverage. In this context, Figure 1 shows that the remote communication device 14 transmits a session establishment request 30 towards the IMS network 20, requesting the establishment of an emergency call session for the remote communication device 14, e.g., where the emergency call session may be an IMS session. The session establishment request 30 may for example be a Session Initiation Protocol, SIP, INVITE request that requests the establishment of an IMS session for an emergency call. An emergency call session is a call session initiated to request emergency assistance or to report an emergency situation. An emergency here includes a situation where immediate help is needed, such as medical emergencies, accidents, or life-threatening events. The IMS network 20 accordingly has protocols and procedures to ensure reliable and priority communication for an emergency call session, e.g., prioritized access, location information transmission, and / or support for emergency services.

[0065] In some embodiments, the session establishment request 30 identifies the remote communication device 14 itself, e.g., as the source or sender of the request 30. As shown in Figure 1, for example, the session establishment request 30 may include a preferred identity header field 32P that indicates an identity 14-ID of the remote communication device 14 (remote ID). Where the session establishment request 30 is a SIP INVITE request, for instance, the preferred identity header field 32P may be a P-Preferred-ldentity header field whose value indicates an identity 14-ID that the remote communication device 14 wishes to be used for identifying the remote communication device 14 in the IMS network 20.

[0066] Either way, with the relay communication device 12 relaying communication for the remote communication device 14, the session establishment request 30 is relayed towards the IMS network 20 via the relay communication device 12. As such, the session establishment request 30 indicates that the session establishment request 30 is relayed via communication device relaying, e.g., as opposed to being transmitted directly to the communication network 10. The session establishment request 30 may for example include an access type parameter (not shown) whose value indicates that the session establishment request is relayed via communication device relaying. Where the relay communication device 12 is a 5G ProSe L3 U2N relay in a New Radio (NR) network, for instance, the access type parameter may be set to a value of “3GPP-NR-ProSe- L3LINR” to indicate that the session establishment request 30 is relayed via 5G ProSe L3 U2N relaying. The session establishment request 30 in these and other embodiments may just generally indicate that the session establishment request 30 is relayed via communication device relaying, without actually identifying which communication device relays the session establishment request 30, i.e. , without actually identifying the relay communication device 12 as the communication device which relays the session establishment request 30.

[0067] According to embodiments herein, though, a proxy server 22 in the IMS network 20 receives the session establishment request 30. The proxy server 22 may for instance implement a Proxy Call Session Control Function (P-CSCF). Regardless, the proxy server 22 modifies the session establishment request 30 before forwarding the request 30M (as modified) to another server 24 in the IMS network 20. The proxy server 22 may for example modify the session establishment request 30M to include an asserted identity header field 32A that indicates the identity 14-1 D of the remote communication device 14 as indicated by the preferred identity header field 32P. Either way, the proxy server 22 according to embodiments herein notably modifies the session establishment request 30 to indicate an identity 12-1 D of the relay communication device 12 that relayed the session establishment request 30.

[0068] In particular, the proxy server 22 modifies the received session establishment request 30 in order to obtain a modified session establishment request 30M which includes an access network information header field 34M that indicates the identity 12-1 D of the relay communication device 12. Where the session establishment request 30 is a SIP INVITE request, for example, the access network information header field 34 may be a P-Access- Network- Info header field, which is a private SIP extension header that carries information related to the access network between a SIP client and its serving proxy. The access network information header field 34M in these and other embodiments indicates information about an access network via which the IMS network 20 was accessed, e.g., including a radio access technology of the access network. Such an access network may be the network that provides Layer 2 or Layer 3 IP connectivity. Especially in the case where the relay communication device 12 provides relaying at Layer 2 or Layer 3, then, the relay communication device 12 may be appropriately understood as providing access via which the IMS network 20 was received. As such, including the identity 12-ID of the relay communication device 12 in the access network information header field 34M advantageously conforms to paradigms for the meaning of fields in a session establishment request.

[0069] The identity 12-ID of the relay communication device 12 may be indicated in the access network information header field 34M as a core network level identity, i.e., at the level of the core network of the communication network 10. Such a core network level identity may an identity available for an IP Connectivity Access (CAN) session within which the session establishment request 30 is communicated. In these and other embodiments, for instance, the identity 12-ID may be a subscription permanent identifier (SUPI), a subscription concealed identifier (SUCI), an International Mobile Subscription Identifier (I MSI) , or a Mobile Station International Subscriber Directory Number (MSISDN). The proxy server 22 may obtain the identity 12-ID of the relay communication device 12 in these and other embodiments by retrieving it from another network node, e.g., a Policy Control Function (PCF) in the communication network 10.

[0070] In any event, the access network information header field 34M may more particularly include a parameter dedicated to explicitly indicating the identity 12-ID of the relay communication device 12. For example, where the relay communication device 12 is a 5G ProSe U2N relay, the access network information header field 34M may include a U2N-relay-ID parameter whose value is set to the identity 12-ID of the relay communication device 12. In some embodiments, the access network information header field 34M further indicates that this identity 12-1 D of the relay communication device 12 is provided by the IMS network 20, e.g., as opposed to having been provided by the remote communication device 14. The access network information header field 34M may for example also include a network-provided parameter which indicates that the access network information header field 34M is network provided. By indicating that the access network information header field 34M is network provided, its content may be deemed as more reliable and / or as having been verified as true.

[0071] Furthermore, the access network information header field 34M may also be how the session establishment request 30 indicates that it is relayed via communication device relaying. The access network information header field 34M may for example also include an access type parameter whose value indicates that the session establishment request 30M (as modified) was relayed via communication device relaying.

[0072] Regardless, by modifying the session establishment request 30M in this way to indicate the identity 12-1 D of the relay communication device 12 which relayed the request, the proxy server 22 advantageously enables the location of the relay communication device 12 to be determined and / or validated, while conforming to existing signaling paradigms. In some embodiments, for example, the remote communication device 14 may indicate a location of the relay communication device 12 in the session establishment request 30, e.g., with a cell identity parameter whose value indicates an identity of a cell in which the relay communication device 12 is located. Some embodiments advantageously enable validation of this device-provided location of the relay communication device 12. That is, by modifying the session establishment request 30 to indicate the identity of the relay communication device 12, rather than just the location of the relay communication device 12 as provided by the remote communication device 14, the proxy server 22 enables the IMS network 20 to validate the location of the relay communication device 12 as provided by the remote communication device 14. Such location validation may prove particularly useful for routing of the emergency call session.

[0073] In fact, in some embodiments, the proxy server 22 only selectively modifies the session establishment request 30M as described above when the session establishment request 30 that it receives: (1) was relayed via communication device relaying; and (ii) indicates the location of the relay communication device 12 as provided by the remote communication device 14. In these embodiments, then, modification of the session establishment request 30M specifically targets validation of the location of the relay communication device 12 that the remote communication device 14 provided.

[0074] Figure 2 shows an example. As shown, the session establishment request 30 from the remote communication device 14 already includes an access network information field 34 provided by the remote communication device 14. This device-provided access network information field 34 includes a relaying indication 36 that indicates the session establishment request 30 is relayed via communication device relaying. The relay indication 36 may for example be an access type parameter whose value (e.g., “3GPP-NR-ProSe-L3UNR”) indicates that the session establishment request 30 is relayed via communication device relaying. The device-provided access network information field 34 as shown also includes a relay location 38, indicating a location of the relay communication device 12 as provided by the remote communication device 14. The relay location 38 may for example be a cell identity parameter whose values indicates the location of the relay communication device 12 as provided by the remote communication device in terms of an identity of the cell in which the relay communication device 12 is located.

[0075] Responsive to determining that the session establishment request 30 was relayed via communication device relaying, and that the session establishment request 30 indicates a location of the relay communication device 12 as provided by the remote communication device 14, the proxy server 22 obtains the identity 12-1 D of the relay communication device 12 that relayed the session establishment request 30. The proxy server 22 may for instance retrieve this identity 12-1 D from a Policy Control Function (PCF) in the communication network 10. The proxy server 22 then modifies the session establishment request 30 as described above. The session establishment request 30M resulting from such modification includes an access network information header field 34M that indicates the identity 12-1 D of the relay communication device 12. The access network information header field 34M may for instance include a relay ID parameter whose value is set to the identity 12-ID of the relay communication device 12.

[0076] Note here that, in some embodiments, the proxy server 22 obtains this modified session establishment request 30M by deleting the device-provided access network information header field 34 in the received session establishment request 30, in favor of a new, network-provided access network information header filed 34M. The proxy server 22 may for example transfer the relaying indication 36 and the relay location 38 from the device-provided access network information header field 34 to the new, network-provided access network information header filed 34M, along with adding the relay ID 12-ID to the new, network-provided access network information header filed 34M.

[0077] The proxy server 22 as shown then forwards the modified session establishment request 30M to another server in the IMS network 20, shown as a server 24E that implements an Emergency Call Session Control Function (E-CSCF), i.e., an E-CSCF server 24E. In receipt of the modified session establishment request 30M, the E-CSCF server 24E in turn transmits a query 40 to a location server 24L (e.g., implementing a Location Retrieval Function, LRF). This query 40 is a query 40 to validate the location 38 of the relay communication device 12 as provided by the remote communication device 14. As such, the query 40 includes the session establishment request 30M as received from the proxy server 22.

[0078] Upon receipt of the query 40, the location server 24L validates the location 38 of the relay communication device 12 as provided by the remote communication device 14. The location server 24L in particular obtains the location of the relay communication device 12 as identified by the identity 12-1 D in the modified session establishment request 30. The location server 24L then compares the obtained location to the location 38 of the relay communication device 21 as provided by the remote communication device 14. If the obtained location matches or otherwise corresponds to the location 38 of the relay communication device 21 as provided by the remote communication device 14, the location server 24L deems that device-provided location 38 as validated. Otherwise, if the obtained location does not match or corresponds to the location 38 of the relay communication device 21 as provided by the remote communication device 14, the location server 24L deems that device-provided location as not validated. The location server 24L may then transmit a response 42 based on the result.

[0079] In some embodiments, for example, if the device-provided location is not validated, the location server 24L does not use that device-provided location to select a Public Safety Answering Point (PSAP) to which to route the session establishment request 30M. But if the device-provided location is validated, the location server 24L may use that device-provided location to select one or more PSAPs 50 to which to route session establishment request 30M. The location server 24L then includes one or more addresses of the selected PSAP(s) 50 in its response 42 to the E-CSCF server 24E. In some embodiments, for instance, the location server 24L sets a contact header field of its response 42 to a list of the one or more selected PSAPs 50 to which to route the session establishment request 30M. The response 42 in this case may for instance be a 300 (Multiple Choices) response. Based on this response 42 from the location server 24L, the E-CSCF 24E may then route the session establishment request 30M, e.g., by routing the session establishment request 30M towards the address of the selected PSAP(s) 50.

[0080] Consider now a specific example where the communication network 10 is a 5G network, the remote communication device 14 is a 5G proSe Remote UE, the relay communication device 12 is a 5G ProSe UE-to-Network Relay, the proxy server 22 implements a Proxy CSCF (P-CSCF), the E-CSCF server 24E implements an E-CSCF, the location server 24L implements a Location Retrieval Function (LRF), the session establishment request 30 is a SIP INVITE request, the access network information header field 34 is a P-Access- Network- Info header field, the preferred identity header field 32P is a P-Asserted Identity header field, and the asserted identity header field 32M is a P-Asserted-ldentity header field, with corresponding reference numbers indicated, e.g., as otherwise consistent with TS 23.304 v18.3.0.

[0081] In this case, the 5G ProSe Remote UE 14 identifies that dialed digits for the requested session correspond to an emergency call. The 5G ProSe Remote UE 14 may obtain the address of the P-CSCF 22 from the 5G ProSe UE-to-Network Relay 12 via the Dynamic Host Configuration Protocol (DHCP). The 5G ProSe Remote UE 14 sets an access type field of the SIP INVITE request 30 to “3GPP-NR-ProSe-L3UNR” in the P-Access- Network- Info header field 34 of SIP INVITE request 30 to the P-CSCF 22 for the access via 5G ProSe UE-to-Network Relay 12 with Layer-3 relaying applied. The 5G ProSe Remote UE 14 also includes in the IMS emergency call SIP INVITE request’s utran-cell-id-3gpp field of the P-Access- Network- Info header field 24, the New Radio (NR) Cell Global Identity (NCGI) obtained from the 5G ProSe UE-to-Network Relay 12, to indicate the location 38 of the 5G ProSe UE-to-Network Relay 12, e.g., otherwise consistent with TS 24.229 v18.3.0 and TS 23.003 v18.3.0). The user location information contains the 5G ProSe UE-to-Network Relay’s location, e.g., see, TS 23.167 v18.1.0.

[0082] When the P-CSCF 22 determines that the emergency call is from a 5G ProSe Remote UE 14 based on the access type field set to “3GPP-NR-ProSe-L3UNR” in the P-Access- Network- Info header field 34 of the emergency call SIP INVITE request 30, the P-CSCF 22 (based on operator policy) obtains from the PCF 23 the UE identity 12-1 D of the 5G ProSe UE-to-Network Relay 12. The P-CSCF 22 provides the NCGI and this UE Identity 12-ID of 5G ProSe UE-to-Network Relay 12 to the E-CSCF 24E. The E-CSCF 22 uses the NCGI and UE Identity 12-ID of 5G ProSe UE-to- Network Relay 12 to query the LRF 24L to validate the NCGI provided by the 5G ProSe Remote UE 14, e.g., as otherwise described in clause 4.3.1 of TS 23.167 v18.1.0. That is, the LRF 24L fetches the location of the 5G ProSe UE-to-Network Relay 12 by using the UE identity 12-ID of the 5G ProSe UE-to-Network Relay 12 and validates the fetched location of the 5G ProSe UE-to- Network Relay 12 against the location provided by the 5G ProSe Remote UE 12 in the utran-cell- id-3gpp field within an access-info parameter of the P-Access- Network- Info header field 34 not containing a “network-provided” parameter of the SIP INVITE request 30, e.g., as otherwise described in S2-2311607.

[0083] Some embodiments in this regard provide a mechanism to convey the identity 12-ID of a 5G ProSe UE-to-Network Relay 12 in an emergency call SIP INVITE request 30 triggered by a 5G ProSe Remote UE 14. Rather than carrying the UE Identity 12-ID from P-CSCF 22 to E-CSCF 24E in the P-Asserted-ldentity header field, which according to existing signaling paradigms carries the identity of the originator of the message (not the identity of any other node), some embodiments herein provide for carrying the UE Identity 12-1 in the P-Access- Network- Info header field 34M of the SIP INVITE request 30M. Some embodiments thereby provide for signaling the identity of another User’s UE (e.g., 5G ProSe UE-to-Network Relay) in a SIP INVITE invoked by a specific user’s UE (e.g., 5G ProSe Remote UE). Generally, then, some embodiments advantageously allow conveying of the identity of another node, such as another User’s UE or a node that is the relay entity providing relaying functionality to support connectivity to the network for Caller and Callee User’s UEs.

[0084] Specific to Proximity based Services (ProSe) context, some embodiments enable conveying the identity of the 5G ProSe UE-to-Network Relay 12, to validate the location of the 5G ProSe UE-to-Network Relay 12 that was provided by a 5G ProSe-enabled Remote UE 12 which is obtaining an emergency service via the 5G ProSe UE-to-Network Relay 14. In particular, some embodiments provide that the P-Access- Network- Info SIP header field carries the identity of the 5G ProSe UE-to-Network Relay 12, e.g., along with location and access type of the 5G ProSe UE- to-Network Relay 12.

[0085] One of the advantages of some embodiments herein is that the P-Access- Network- Info SIP header field which carries the network-provided location of the 5G ProSe UE-to-Network Relay 12 will also carry the identity of the 5G ProSE UE-to-Network relay 12 serving the 5G ProSE remote UE 12. So, in one SIP header field, information of another UE which is acting as relay UE is confirmed in the SIP INVITE message.

[0086] Another advantage of some embodiments is that existing SIP header fields which carry the asserted identities of the caller remain intact according to existing signaling paradigms.

[0087] In more detail, some embodiments herein include a method of conveying the identity of the 5G ProSe UE-to-Network Relay 12, to validate the location of the 5G ProSe UE-to-Network Relay 12 that was provided by a 5G ProSe-enabled Remote UE 12 which is obtaining emergency service via the 5G ProSe UE-to-Network Relay 12.

[0088] The method comprises receiving, by the P-CSCF 22, an INVITE message 30 indicating an emergency call triggered from the 5G ProSe Remote UE 14 and relayed by the 5G ProSe UE-to- Network Relay 12. The P-CSCF 22 determines that the emergency call is from a 5G ProSe Remote UE 14 based on the access type field set to "3GPP-NR-ProSe-L3UNR" in the P-Access- Network-lnfo header field 34 of the emergency call SIP INVITE request 30. The location 38 of the 5G ProSe UE-to-Network Relay 12, which is provided by the 5G ProSe-enabled Remote UE 14, is set in a utran-cell-id-3gpp field within an access-info parameter of the P-Access- Network- Info header field 34 of the emergency call SIP INVITE request 30.

[0089] The method further comprises retrieving, by the P-CSCF 22, the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 from the PCF 23, to allow validation of the location 38 provided by the 5G ProSe-enabled Remote UE 14 subsequently by a network location service during the emergency call.

[0090] The method further comprises sending, by the P-CSCF 22, an updated SIP INVITE message 30M to the E-CSCF 24E. The updated SIP INVITE message 30M contains: (i) the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 in the P-Access- Network- Info header field 34M containing the “network-provided” parameter; (ii) the location 38 of the 5G ProSe UE-to-Network Relay 12, which was provided by the 5G ProSe-enabled Remote UE 14, set in utran-cell-id-3gpp field within an access-info parameter of the P-Access- Network- Info header field 34M without “network-provided” parameter; and (iii) the identity 14-ID of the 5G ProSe Remote UE 14 in the P- Asserted Identity header field 34.

[0091] The method further comprises receiving, by the E-CSCF 24E, the updated INVITE message 30M indicating the emergency call from the 5G ProSe Remote UE 14, as relayed by the 5G ProSe UE-to-Network Relay 12. The E-CSCF 24E uses the identity 12-ID of the 5G ProSe UE- to-Network Relay 12 provided in the P-Access-Network-Info header field 34M with “network- provided” parameter and the location 38 of the 5G ProSe UE-to-Network Relay 12, as provided by the 5G ProSe-enabled Remote UE 14 in the utran-cell-id-3gpp field within the access-info parameter of the P-Access- Network- Info Header field 34 without “network-provided” parameter, to query the LRF 24L to validate the location 38 provided by the 5G ProSe Remote UE 14.

[0092] The method further comprises receiving, by the LRF 24L, a location retrieval request with the access-type field of the P-Access- Network- Info header field 34M not containing "network- provided" parameter set to "3GPP-NR-ProSe-L3UNR". A location is retrieved by the LRF 24L using the "U2N-relay-ID" parameter of the P-Access-Network-Info header field 34M containing the "network-provided" parameter. The LRF 24L matches the retrieved location with the user-provided location from the P-Access-Network-Info header field 34M not containing the "network-provided" parameter. If a matching operation is not successful, the LRF 24L shall not use the location retrieved from the P-Access-Network-Info header field 34M not containing the "network-provided" parameter when selecting PSAP(s) 50.

[0093] As one embodiment, the P-CSCF 22 would provide the SUPI as the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 in a new parameter (e.g., U2N-relay-ID) of the P-Access- Network- Info header field 34M containing the network-provided parameter. For example, the U2N-relay-ID parameter may be structured as follows:

[0094] U2N-relay-ID = "U2N-relay-ID" EQUAL DQUOTE <SUPI of 5G ProSe UE-to-Network Relay in NAI formats DQUOTE

[0095] SUPI format may be SUPI-Type+IMSI

[0096] For example:

[0097] SUPI: typeO

[0098] IMSI: Assuming the IMSI 234150999999999, where MCC=234, MNC=15 and MSIN=0999999999, where MCC stands for Mobile Country Code, MNC stands for Mobile Network Code, and MSIN stands for Mobile Subscriber Identification Number.

[0099] Thus, SUPI can be for example 0234150999999999.

[0100] As another embodiment, the P-CSCF 22 may provide the IMSI as the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 in a new parameter (e.g., U2N-relay-ID) of P-Access-Network- Info header field 34M containing the network-provided parameter. For example, the U2N-relay-ID parameter may be structured as follows:

[0101] U2N-relay-ID = "U2N-relay-ID" EQUAL DQUOTE <IMSI of 5G ProSe UE-to-Network Relay > DQUOTE

[0102] Thus, IMSI can be for example 234150999999999 (See, TS 23.003 v18.3.0).

[0103] As yet another embodiment, the P-CSCF 22 may provide the MSISDN as the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 in a new parameter (e.g., U2N-relay-ID) of the P-Access- Network-lnfo header field 34M containing the network-provided parameter. For example, the U2N- relay-ID parameter may be structured as follows: U2N-relay-ID = "U2N-relay-ID" EQUAL DQUOTE <MSISDN of 5G ProSe UE-to-Network Relay > DQUOTE

[0104] Thus, MSISDN can be for example 12123456789. (See, TS 23.003 v18.3.0).

[0105] As still a further embodiment, the P-CSCF 22 may provide the SUCI as the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 in a new parameter (e.g., U2N-relay-ID) of the P-Access- Network-lnfo header field 34M containing the network-provided parameter. For example, the U2N- relay-ID parameter can be structured as follows:

[0106] U2N-relay-ID = "U2N-relay-ID" EQUAL DQUOTE <SUCI of 5G ProSe UE-to-Network Relay in NAI formats DQUOTE

[0107] Thus, SUCI can be for example type0.rid678.schid0.userid0999999999@5gc.mnc015.mcc234.3gppnetwork.org

[0108] Figure 3 shows one example call flow for an emergency call from a 5G ProSE remote UE 14 via a 5G ProSE UE-to-Network relay 14 serving the 5G ProSE remote UE 12 according to some embodiments. Note here that the emergency call is between the 5G ProSE remote UE 14 and a PSAP 50, where the 5G ProSe Remote UE 14 does not have a direct connection to the network for emergency service. The 5G ProSe Remote UE 14 thereby obtains emergency service via the 5G ProSe UE-to-Network Relay 12.

[0109] Stepl : A 5G ProSe Remote UE 14 has discovered a 5G ProSe UE-to-Network Relay 12 and obtains additional parameters like P-CSCF address, Location (NCGI) of the serving cell of the 5G ProSe UE-to-Network Relay 12, etc.

[0110] Step2: 5G ProSe Remote UE 14 originates an IMS emergency call by sending a SIP INVITE request 30 to the P-CSCF 22 for the emergency service access via 5G ProSe UE-to- Network Relay 12. In the emergency call request 30, the 5G ProSe Remote UE 14 sets the access type field to "3GPP-NR-ProSe-L3UNR" in P-Access- Network- Info header field 30 of the SIP INVITE request 30 to the P-CSCF 22, for the access via 5G ProSe UE-to-Network Relay 12, based on Layer-3 relaying. The 5G ProSe Remote UE 14 shall also include in utran-cell-id-3gpp field withing the access-info parameter of the P-Access- Network- Info header field 30, the NR Cell Global Identity (NCGI) obtained from the 5G ProSe UE-to-Network Relay 12. The 5G ProSe Remote UE 14 also sets its identities in the P-Preferred Identity header field 30 of the IMS emergency call SIP INVITE request 30.

[0111] Step3: When the P-CSCF 22 determines that the emergency call is from a 5G ProSe Remote UE 14 based on the access type field set to “3GPP-NR-ProSe-L3UNR” in the P-Access- Network-lnfo header field 30 of the IMS emergency SIP INVITE request 30, the P-CSCF 22 retrieves the identity 12-ID of the 5G ProSe UE-to-Network Relay 12 from the PCF 23. The functionality of P-CSCF 22 retrieving the UE ID 12-ID from the PCF 23 is described in TS 23.167 V18.1.0. The P-CSCF 22 extends the outgoing IMS emergency SIP INVITE request 30 with the P- Access- Network- Info header field 30M containing the “network-provided” parameter by including the U2N-relay-ID parameter value set to an identity 12-ID of the 5G ProSe UE-to-Network Relay 12 retrieved from the PCF 23.

[0112] Step4: The P-CSCF 23 sends the updated IMS emergency SIP INVITE request 30M to the E-CSCF 24E.

[0113] Step5: The E-CSCF 24E forwards the INVITE request 30M to the LRF 24L. The LRF 24L validates the location information of 5G ProSe UE-to-Network Relay 12 provided by the 5G ProSe Remote UE 14, by using the NR Cell Global Identity (NCGI) present in utran-cell-id-3gpp field within the access-info parameter of the P-Access- Network- Info header field 34M without “network- provided” parameter and the UE Identify 12-ID of 5G ProSe UE-to-Network Relay 12 provided in the U2N-relay-ID parameter of the P-Access-Network-Info header field 34M with “network- provided” parameter of the IMS emergency SIP INVITE request 30M. The LRF 24L successfully validates the location of 5G ProSe UE-to-Network Relay 12 provided by 5G ProSe Remote UE 14.

[0114] Step6: The E-CSCF 24E sends the IMS emergency SIP INVITE request 30M to the PSAP 50.

[0115] Step7-Step9: The PSAP 50 successfully answers the IMS emergency call request 30M from the 5G ProSe Remote UE 14.

[0116] Step10-Step12: The 5G ProSe Remote UE 14 acknowledges the reception of IMS emergency call answer from PSAP 50.

[0117] Embodiments exemplified herein are thereby applicable for the P-CSCF 22 anchoring the emergency call invoked by a 5G ProSE remote UE 14 via a 5G ProSE UE-to-Network relay 12 serving the 5G ProSE remote UE 12. Embodiments herein are also applicable for the E-CSCF 24E anchoring the emergency call invoked by a 5G ProSE remote UE 14 via a 5G ProSE UE-to- Network relay 12 serving the 5G ProSE remote UE 14. Embodiments herein are further applicable for the LRF 24L anchoring the location retrieval and validation for an emergency call invoked by the 5G ProSE remote UE 14 via a 5G ProSE UE-to-Network relay 12 serving the 5G ProSE remote UE 14.

[0118] Note, too, that some embodiments herein are centralized in P-CSCF and LRF and may be applied in a distributed manner across multiple nodes, without any specific consideration. Similarly, some embodiments will work in an Open Radio Area Network (O-RAN) architecture, without any specific consideration, as they are centralized in P-CSCF and LRF.

[0119] Consider now a specific implementation of some embodiments herein for emergency call sessions, in terms of changes to TS 24.229 v18.3.0.

[0120] A first change to TS 24.229 v18.3.0 would be to update section 5.1.6.8.3 as follows. Under addition #4, note that if the UE accessing the network via a 5G ProSe UE-to-network relay UE, the location information in the P-Access-Network-Info header field refers to the location information obtained from the 5G ProSe UE-to-network relay UE to which the UE is connected to as specified in 3GPP TS 24.554.

[0121] A next change to TS 24.229 v18.3.0 would be to update section 5.2.1 as follows. In a step 3A, if the P-CSCF determines that the initial INVITE request from the UE is related to an emergency call, the PCRF is used to support the access technology for this UE, 3GPP-User- Location-lnfo as specified in 3GPP TS 29.214 is available, and the access-type field of the received P-Access-Network-Info header field parameter is set to "3GPP-NR-ProSe-L3UNR", then the P-CSCF shall retrieve the EPC-level identities available for the IP-CAN session from the PCRF. If an I MSI is retrieved from the PCRF as an EPC-level identity available for the IP-CAN session, the P-CSCF shall insert the P-Access-Network-Info header field constructed according to step 4 d) in the INVITE request and include the "U2N-relay-ID" parameter set to the retrieved IMSI in the P-Access-Network-Info header field with the "network-provided" parameter and skip step 4. Note here that , if the P-CSCF received a SIP INVITE request with a P-Access-Network-Info header field containing a "network-provided" parameter, the P-CSCF will remove that P-Access- Network-lnfo header field, create a new P-Access-Network-Info header field according to step 3A (i.e. with the "U2N-relay-ID" parameter set to the retrieved IMSI and include the "network-provided" parameter), and insert created P-Access-Network-Info header field in the INVITE request.

[0122] Another change to TS 24.229 v18.3.0 would be to update section 5.12.2 as follows. In a step 2B, if the access-type field of the P-Access-Network-Info header field not containing "network- provided" parameter is set to "3GPP-NR-ProSe-L3UNR", a location is retrieved using "U2N-relay- ID" parameter of the P-Access-Network-Info header field containing the "network-provided" parameter, and the retrieved location does not match the user-provided location from the P- Access- Network- Info header field not containing the "network-provided" parameter, then the LRF shall not use the location retrieved from the P-Access-Network-Info header field not containing the "network-provided" parameter when selecting PSAP(s).

[0123] Another change to TS 24.229 v18.3.0 would be to update section 7.2. A.4.2 as follows. Table 7.2A.4 describes the 3GPP-specific extended syntax of the P-Access-Network-Info header field defined in RFC 7315 and RFC 7913.

[0124] Table 7.2A.4: Syntax of extended P-Access-Network-Info header field

[0125] The U2N-relay-ID parameter indicates the IMSI as described in 3GPP TS 23.003, of 5G ProSe UE-to-network relay, when the call request is triggered from the 5G ProSe remote UE and relayed by the 5G ProSe UE-to-network relay. The IMSI is encoded as specified in 3GPP TS 29.228. The U2N-relay-ID parameter can be set only by the P-CSCF.

[0126] Another change to TS 24.229 v18.3.0 would be to update section 7.2. A.4.3 as follows. In item 27, if the access-type field of the P-Access-Network-Info header field not containing "network- provided" parameter is equal to "3GPP-NR-ProSe-L3UNR" and the access-class field of the P- Access- Network- Info header field containing "network-provided" parameter is equal to "3GPP-NR", then an "U2N-relay-ID" parameter of the P-Access-Network-Info header field containing the "network-provided" parameter set to the IMSI of 5G ProSe UE-to-network relay.

[0127] In view of the modifications and variations herein, Figure 4 depicts a method performed by proxy server 22 in an Internet Protocol, IP, Multimedia Subsystem, IMS, network 20 in accordance with particular embodiments. The method includes receiving a session establishment request 30 from a remote communication device 14 requesting establishment of an emergency call session (Block 400). The session establishment request 30 indicates the session establishment request 30 was relayed via communication device relaying. The method also comprises obtaining an identity 12-ID of a relay communication device 12 that relayed the session establishment request 30 (Block 410). The method also comprises modifying the session establishment request 30 to include an access network information header field 34M that indicates the identity 12-ID of the relay communication device 12 (Block 420). The method also comprises forwarding the modified session establishment request 30M to another server 24 in the IMS network 20 (Block 430).

[0128] In some embodiments, the session establishment request 30 is a Session Initiation Protocol, SIP, INVITE request. In some embodiments, the proxy server 22 implements a Proxy Call Session Control Function, P-CSCF.

[0129] In some embodiments, the access network information header field 34M is a P-Access- Network-lnfo header field.

[0130] In some embodiments, the relay communication device 12 is a 5G Proximity Services, ProSe, user equipment to network, U2N, relay, and the access network information header field 34M includes a U2N-relay-ID parameter whose value is set to the identity 12-ID of the relay communication device 12.

[0131] In some embodiments, the identity 12-ID of the relay communication device 12 is a core network level identity available for an Internet Protocol, IP, Connectivity Access Network, CAN, session within which the session establishment request 30 is received.

[0132] In some embodiments, the identity 12-ID of the relay communication device 12 is a subscription permanent identifier, SlIPI. In other embodiments, the identity 12-ID of the relay communication device 12 is a subscription concealed identifier, SlICI. In yet other embodiments, the identity 12-ID of the relay communication device 12 is an International Mobile Subscription Identifier, IMSI. In still yet other embodiments, the identity 12-ID of the relay communication device 12 is a Mobile Station International Subscriber Directory Number, MSISDN.

[0133] In some embodiments, the access network information header field 34M further indicates that the identity 12-ID of the relay communication device 12 is provided by the IMS network 20.

[0134] In some embodiments, the modified session establishment request 30M is forwarded to a server 24E that implements an emergency Call Session Control Function, E-CSCF.

[0135] In some embodiments, the access network information header field 34M further indicates that the session establishment request 30 was relayed via communication device relaying. In other embodiments, the access network information header field 34M further indicates alternatively or additionally a location of the relay communication device 12 as provided by the remote communication device 14. In some embodiments, the access network information header field 34M includes an access type parameter whose value indicates that the session establishment request 30 was relayed via communication device relaying. In other embodiments, the access network information header field 34M alternatively or additionally includes a cell identity parameter whose value indicates the location of the relay communication device 12 in terms of an identity of a cell in which the relay communication device 12 is located.

[0136] In some embodiments, said obtaining comprises retrieving the identity 12-ID of the relay communication device 12 from a Policy Control Function, PCF.

[0137] In some embodiments, said obtaining and modifying is performed responsive to (i) determining that the session establishment request 30 was relayed via communication device relaying; and (ii) determining that the session establishment request 30 as received indicates a location of the relay communication device 12 as provided by the remote communication device 14.

[0138] In some embodiments, the session establishment request 30 as received includes a preferred identity header field 32P that indicates an identity 14-1 D of the remote communication device 14, and the session establishment request 30 as modified further includes an asserted identity header field 32A that indicates the identity 14-ID of the remote communication device 14 as indicated by the preferred identity header field 32P.

[0139] In some embodiments, the relay communication device 12 is a 5G Proximity Services, ProSe, UE-to-Network relay, and / or the remote communication device 14 is a 5G ProSe Remote UE.

[0140] Figure 5 depicts a method performed by a server 24 in an Internet Protocol, IP, Multimedia Subsystem, IMS, network 20 in accordance with other particular embodiments. The method includes receiving, by the server 24, a session establishment request 30 requesting an emergency call session for a remote communication device 14 (Block 500). The session establishment request 30 indicates the session establishment request 30 was relayed via communication device relaying and includes an access network information header field 34M that indicates an identity 12-1 D of a relay communication device 12 that relayed the session establishment request 30.

[0141] In some embodiments, the session establishment request 30 is a Session Initiation Protocol, SIP, INVITE request.

[0142] In some embodiments, the access network information header field 34M is a P-Access- Network-lnfo header field.

[0143] In some embodiments, the relay communication device 12 is a 5G Proximity Services, ProSe, user equipment to network, U2N, relay, and the access network information header field 34M includes a U2N-relay-ID parameter whose value is set to the identity 12-ID of the relay communication device 12.

[0144] In some embodiments, the identity 12-ID of the relay communication device 12 is a core network level identity available for an Internet Protocol, IP, Connectivity Access Network, CAN, session within which the session establishment request 30 is received.

[0145] In some embodiments, the identity 12-ID of the relay communication device 12 is a subscription permanent identifier, SlIPI. In other embodiments, the identity 12-ID of the relay communication device 12 is a subscription concealed identifier, SlICI. In yet other embodiments, the identity 12-ID of the relay communication device 12 is an International Mobile Subscription Identifier, IMSI. In still yet other embodiments, the identity 12-ID of the relay communication device 12 is a Mobile Station International Subscriber Directory Number, MSISDN.

[0146] In some embodiments, the access network information header field 34M further indicates that the identity 12-ID of the relay communication device 12 is provided by the IMS network 20. In some embodiments, the relay communication device 12 provides communication device relaying via Layer 2 or Layer 3. In one such embodiment, the access network information header field 34M indicates information about an access network providing Layer 2 or Layer 3 connectivity via which the IMS network 20 was accessed and includes a relay ID parameter whose value is set to the identity 12-ID of the relay communication device 12.

[0147] In some embodiments, the access network information header field 34M further indicates that the session establishment request 30 was relayed via communication device relaying. In other embodiments, the access network information header field 34M further indicates alternatively or additionally a location of the relay communication device 12 as provided by the remote communication device 14. In some embodiments, the access network information header field 34M includes an access type parameter whose value indicates that the session establishment request 30 was relayed via communication device relaying. In other embodiments, the access network information header field 34M alternatively or additionally includes a cell identity parameter whose value indicates the location of the relay communication device 12 in terms of an identity of a cell in which the relay communication device 12 is located.

[0148] In some embodiments, the session establishment request 30 further includes an asserted identity header field 32A that indicates the identity 14-ID of the remote communication device 14.

[0149] In some embodiments, the relay communication device 12 is a 5G Proximity Services, ProSe, UE-to-Network relay, and / or the remote communication device 14 is a 5G ProSe Remote UE.

[0150] In some embodiments, the session establishment request 30 is received from a proxy server 22 that implements a Proxy Call Session Control Function, P-CSCF. In some embodiments, the server 24E implements an emergency Call Session Control Function, E-CSCF.

[0151] In some embodiments, such as when the server 24E implements an E-CSCF, the session establishment request 30 indicates a location of the relay communication device 12 as provided by the remote communication device 14, and the method further comprises transmitting, to a location server 24L, a query to validate the location of the relay communication device 12 as provided by the remote communication device 14 (Block 505). In one such embodiment, the query includes the session establishment request 30. In some embodiments, the method further comprises receiving a response to the query (Block 510). In some embodiments, the method further comprises routing the session establishment request 30 based on the response (Block 520). In some embodiments, the response indicates an address of a selected Public Safety Answering Point, PSAP, for the emergency call session, and routing the session establishment request 30 comprises routing the session establishment request 30 towards the address of the selected PSAP.

[0152] In other embodiments, the session establishment request 30 is received from an emergency Call Session Control Function, E-CSCF, 24E and the server 24L implements a location retrieval function, LRF. In some embodiments, such as when the server 24E implements an LRF, the session establishment request 30 indicates a location of the relay communication device 12 as provided by the remote communication device 14, and the session establishment request 30 is received in a query to validate the location of the relay communication device 12 as provided by the remote communication device 14. In one such embodiment, as an alternative to Steps 505, 510, and 520, the method further comprises validating the location of the relay communication device 12 as provided by the remote communication device 14 (Block 530). In some embodiments, the validation comprises obtaining a location of the relay communication device 12 identified by the identity 12-1 D and comparing the obtained location to the location of the relay communication as provided by the remote communication device 14. Regardless, in some embodiments, the method further comprises transmitting a response to the query based on said validating (Block 540).

[0153] Embodiments herein also include corresponding apparatuses. Embodiments herein for instance include a proxy server 22 configured to perform any of the steps of any of the embodiments described above for the proxy server 22.

[0154] Embodiments also include a proxy server 22comprising processing circuitry and power supply circuitry. The processing circuitry is configured to perform any of the steps of any of the embodiments described above for the proxy server 22. The power supply circuitry is configured to supply power to the proxy server 22.

[0155] Embodiments further include a proxy server 22comprising processing circuitry. The processing circuitry is configured to perform any of the steps of any of the embodiments described above for the proxy server 22. In some embodiments, the proxy server 22 further comprises communication circuitry.

[0156] Embodiments further include a proxy server 22comprising processing circuitry and memory. The memory contains instructions executable by the processing circuitry whereby the proxy server 22 is configured to perform any of the steps of any of the embodiments described above for the proxy server 22.

[0157] Embodiments herein also include a server 24 configured to perform any of the steps of any of the embodiments described above for the server 24.

[0158] Embodiments also include a server 24 comprising processing circuitry and power supply circuitry. The processing circuitry is configured to perform any of the steps of any of the embodiments described above for the server 24. The power supply circuitry is configured to supply power to the server 24.

[0159] Embodiments further include a server 24 comprising processing circuitry. The processing circuitry is configured to perform any of the steps of any of the embodiments described above for the server 24. In some embodiments, the server 24 further comprises communication circuitry.

[0160] Embodiments further include a server 24 comprising processing circuitry and memory. The memory contains instructions executable by the processing circuitry whereby the server 24 is configured to perform any of the steps of any of the embodiments described above for the server

[0161] 24.

[0162] More particularly, the apparatuses described above may perform the methods herein and any other processing by implementing any functional means, modules, units, or circuitry. In one embodiment, for example, the apparatuses comprise respective circuits or circuitry configured to perform the steps shown in the method figures. The circuits or circuitry in this regard may comprise circuits dedicated to performing certain functional processing and / or one or more microprocessors in conjunction with memory. For instance, the circuitry may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory may include program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein, in several embodiments. In embodiments that employ memory, the memory stores program code that, when executed by the one or more processors, carries out the techniques described herein.

[0163] Figure 6 for example illustrates a proxy server 22 as implemented in accordance with one or more embodiments. As shown, the proxy server 22 includes processing circuitry 610 and communication circuitry 620. The communication circuitry 620 is configured to transmit and / or receive information to and / or from one or more other nodes, e.g., via any communication technology. The processing circuitry 610 is configured to perform processing described above, e.g., in Figure 4, such as by executing instructions stored in memory 630. The processing circuitry 610 in this regard may implement certain functional means, units, or modules.

[0164] Figure 7 illustrates a server 24 as implemented in accordance with one or more embodiments. The server 24 may for example implement an E-CSCF or LRF in an IMS network 20 as described above. Regardless, as shown, the server 24 includes processing circuitry 710 and communication circuitry 720. The communication circuitry 720 is configured to transmit and / or receive information to and / or from one or more other nodes, e.g., via any communication technology. The processing circuitry 710 is configured to perform processing described above, e.g., in Figure 5, such as by executing instructions stored in memory 730. The processing circuitry 710 in this regard may implement certain functional means, units, or modules.

[0165] Those skilled in the art will also appreciate that embodiments herein further include corresponding computer programs.

[0166] A computer program comprises instructions which, when executed on at least one processor of an apparatus, cause the apparatus to carry out any of the respective processing described above. A computer program in this regard may comprise one or more code modules corresponding to the means or units described above.

[0167] Embodiments further include a carrier containing such a computer program. This carrier may comprise one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

[0168] In this regard, embodiments herein also include a computer program product stored on a non-transitory computer readable (storage or recording) medium and comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform as described above.

[0169] Embodiments further include a computer program product comprising program code portions for performing the steps of any of the embodiments herein when the computer program product is executed by a computing device. This computer program product may be stored on a computer readable recording medium.

[0170] Figure 8 shows an example of a communication system 800 in accordance with some embodiments.

[0171] In the example, the communication system 800 includes a telecommunication network 802 that includes an access network 804, such as a radio access network (RAN), and a core network 806, which includes one or more core network nodes 808. The access network 804 includes one or more access network nodes, such as network nodes 810a and 810b (one or more of which may be generally referred to as network nodes 810), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 802 includes one or more Open- RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 802 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 802, including one or more network nodes 810 and / or core network nodes 808.

[0172] Examples of an ORAN network node include an open radio unit (0-Rll), an open distributed unit (0-Dll), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1, F1, W1, E1 , E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 810 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 812a, 812b, 812c, and 812d (one or more of which may be generally referred to as UEs 812) to the core network 806 over one or more wireless connections.

[0173] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 800 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 800 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0174] The UEs 812 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 810 and other communication devices. Similarly, the network nodes 810 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 812 and / or with other network nodes or equipment in the telecommunication network 802 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 802.

[0175] In the depicted example, the core network 806 connects the network nodes 810 to one or more hosts, such as host 816. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 806 includes one more core network nodes (e.g., core network node 808) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 808. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0176] The host 816 may be under the ownership or control of a service provider other than an operator or provider of the access network 804 and / or the telecommunication network 802, and may be operated by the service provider or on behalf of the service provider. The host 816 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0177] As a whole, the communication system 800 of Figure 8 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0178] In some examples, the telecommunication network 802 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 802 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 802. For example, the telecommunications network 802 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0179] In some examples, the UEs 812 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 804 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 804. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC). In the example, the hub 814 communicates with the access network 804 to facilitate indirect communication between one or more UEs (e.g., UE 812c and / or 812d) and network nodes (e.g., network node 810b). In some examples, the hub 814 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 814 may be a broadband router enabling access to the core network 806 for the UEs. As another example, the hub 814 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 810, or by executable code, script, process, or other instructions in the hub 814. As another example, the hub 814 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 814 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 814 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 814 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 814 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0180] The hub 814 may have a constant / persistent or intermittent connection to the network node 810b. The hub 814 may also allow for a different communication scheme and / or schedule between the hub 814 and UEs (e.g., UE 812c and / or 812d), and between the hub 814 and the core network 806. In other examples, the hub 814 is connected to the core network 806 and / or one or more UEs via a wired connection. Moreover, the hub 814 may be configured to connect to an M2M service provider over the access network 804 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 810 while still connected via the hub 814 via a wired or wireless connection. In some embodiments, the hub 814 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 810b. In other embodiments, the hub 814 may be a nondedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 810b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0181] Figure 9 shows a UE 900 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0182] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0183] The UE 900 includes processing circuitry 902 that is operatively coupled via a bus 904 to an input / output interface 906, a power source 908, a memory 910, a communication interface 912, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 9. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0184] The processing circuitry 902 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 910. The processing circuitry 902 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field- programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 902 may include multiple central processing units (CPUs).

[0185] In the example, the input / output interface 906 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 900. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0186] In some embodiments, the power source 908 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 908 may further include power circuitry for delivering power from the power source 908 itself, and / or an external power source, to the various parts of the UE 900 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 908. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 908 to make the power suitable for the respective components of the UE 900 to which power is supplied.

[0187] The memory 910 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 910 includes one or more application programs 914, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 916. The memory 910 may store, for use by the UE 900, any of a variety of various operating systems or combinations of operating systems.

[0188] The memory 910 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 910 may allow the UE 900 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 910, which may be or comprise a device-readable storage medium.

[0189] The processing circuitry 902 may be configured to communicate with an access network or other network using the communication interface 912. The communication interface 912 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 922. The communication interface 912 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 918 and / or a receiver 920 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 918 and receiver 920 may be coupled to one or more antennas (e.g., antenna 922) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0190] In the illustrated embodiment, communication functions of the communication interface 912 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0191] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 912, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0192] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0193] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 900 shown in Figure 9.

[0194] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0195] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0196] Figure 10 shows a network node 1000 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0197] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0198] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, SelfOrganizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0199] The network node 1000 includes a processing circuitry 1002, a memory 1004, a communication interface 1006, and a power source 1008. The network node 1000 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1000 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1000 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1004 for different RATs) and some components may be reused (e.g., a same antenna 1010 may be shared by different RATs). The network node 1000 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1000, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1000.

[0200] The processing circuitry 1002 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1000 components, such as the memory 1004, to provide network node 1000 functionality. In some embodiments, the processing circuitry 1002 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1002 includes one or more of radio frequency (RF) transceiver circuitry 1012 and baseband processing circuitry 1014. In some embodiments, the radio frequency (RF) transceiver circuitry 1012 and the baseband processing circuitry 1014 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1012 and baseband processing circuitry 1014 may be on the same chip or set of chips, boards, or units.

[0201] The memory 1004 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or nonvolatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1002. The memory 1004 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1002 and utilized by the network node 1000. The memory 1004 may be used to store any calculations made by the processing circuitry 1002 and / or any data received via the communication interface 1006. In some embodiments, the processing circuitry 1002 and memory 1004 is integrated.

[0202] The communication interface 1006 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1006 comprises port(s) / terminal(s) 1016 to send and receive data, for example to and from a network over a wired connection. The communication interface 1006 also includes radio front-end circuitry 1018 that may be coupled to, or in certain embodiments a part of, the antenna 1010. Radio front-end circuitry 1018 comprises filters 1020 and amplifiers 1022. The radio front-end circuitry 1018 may be connected to an antenna 1010 and processing circuitry 1002. The radio front-end circuitry may be configured to condition signals communicated between antenna 1010 and processing circuitry 1002. The radio front-end circuitry 1018 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio frontend circuitry 1018 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1020 and / or amplifiers 1022. The radio signal may then be transmitted via the antenna 1010. Similarly, when receiving data, the antenna 1010 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1018. The digital data may be passed to the processing circuitry 1002. In other embodiments, the communication interface may comprise different components and / or different combinations of components. In certain alternative embodiments, the network node 1000 does not include separate radio front-end circuitry 1018, instead, the processing circuitry 1002 includes radio front-end circuitry and is connected to the antenna 1010. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1012 is part of the communication interface 1006. In still other embodiments, the communication interface 1006 includes one or more ports or terminals 1016, the radio frontend circuitry 1018, and the RF transceiver circuitry 1012, as part of a radio unit (not shown), and the communication interface 1006 communicates with the baseband processing circuitry 1014, which is part of a digital unit (not shown).

[0203] The antenna 1010 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1010 may be coupled to the radio front-end circuitry 1018 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1010 is separate from the network node 1000 and connectable to the network node 1000 through an interface or port.

[0204] The antenna 1010, communication interface 1006, and / or the processing circuitry 1002 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1010, the communication interface 1006, and / or the processing circuitry 1002 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0205] The power source 1008 provides power to the various components of network node 1000 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1008 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1000 with power for performing the functionality described herein. For example, the network node 1000 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1008. As a further example, the power source 1008 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0206] Embodiments of the network node 1000 may include additional components beyond those shown in Figure 10 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1000 may include user interface equipment to allow input of information into the network node 1000 and to allow output of information from the network node 1000. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1000.

[0207] Figure 11 is a block diagram of a host 1100, which may be an embodiment of the host 816 of Figure 8, in accordance with various aspects described herein. As used herein, the host 1100 may be or comprise various combinations hardware and / or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 1100 may provide one or more services to one or more UEs.

[0208] The host 1100 includes processing circuitry 1102 that is operatively coupled via a bus 1104 to an input / output interface 1106, a network interface 1108, a power source 1110, and a memory 1112. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 9 and 10, such that the descriptions thereof are generally applicable to the corresponding components of host 1100.

[0209] The memory 1112 may include one or more computer programs including one or more host application programs 1114 and data 1116, which may include user data, e.g., data generated by a UE for the host 1100 or data generated by the host 1100 for a UE. Embodiments of the host 1100 may utilize only a subset or all of the components shown. The host application programs 1114 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAG, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs 1114 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 1100 may select and / or indicate a different host for over-the-top services for a UE. The host application programs 1114 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG- DASH), etc.

[0210] Figure 12 is a block diagram illustrating a virtualization environment 1200 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1200 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1200 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0211] Applications 1202 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0212] Hardware 1204 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1206 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1208a and 1208b (one or more of which may be generally referred to as VMs 1208), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1206 may present a virtual operating platform that appears like networking hardware to the VMs 1208.

[0213] The VMs 1208 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1206. Different embodiments of the instance of a virtual appliance 1202 may be implemented on one or more of VMs 1208, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0214] In the context of NFV, a VM 1208 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1208, and that part of hardware 1204 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1208 on top of the hardware 1204 and corresponds to the application 1202.

[0215] Hardware 1204 may be implemented in a standalone network node with generic or specific components. Hardware 1204 may implement some functions via virtualization. Alternatively, hardware 1204 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1210, which, among others, oversees lifecycle management of applications 1202. In some embodiments, hardware 1204 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1212 which may alternatively be used for communication between hardware nodes and radio units.

[0216] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non- computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0217] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0218] Notably, modifications and other embodiments of the present disclosure will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the present disclosure is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0219] REFERENCES

[0220] 1. 3GPP, TS 23.167 v18.1.0, IP Multimedia Subsystem (IMS) emergency sessions

[0221] 2. 3GPP, TS 24.229 v18.3.0, IP multimedia call control protocol based on Session Initiation Protocol (SlP)and Session Description Protocol (SDP); Stage 3

[0222] 3. 3GPP, TS 23.304 v18.3.0 Proximity based Services (ProSe) in the 5G System (5GS)

[0223] 4. C1-239109, Location validation for L3 remote UE during emergency service, TS 24.229, CR 6647

[0224] 5. S2-2311607, Location validation for the L3 remote UE by the E-CSCF, TS 23.167, CR 0373

[0225] 6. 3GPP, TS 23.003 v18.3.0 Numbering, addressing and identification

Claims

CLAIMS1. A method performed by a proxy server (22) in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20), the method comprising: receiving (400) a session establishment request (30) from a remote communication device (14) requesting establishment of an emergency call session, wherein the session establishment request (30) indicates the session establishment request (30) was relayed via communication device relaying; obtaining (410) an identity (12-1 D) of a relay communication device (12) that relayed the session establishment request (30); modifying (420) the session establishment request (30) to include an access network information header field (34M) that indicates the identity (12-1 D) of the relay communication device (12); and forwarding (430) the modified session establishment request (30M) to another server (24) in the IMS network (20).

2. The method of claim 1, wherein the session establishment request (30) is a Session Initiation Protocol, SIP, INVITE request.

3. The method of any of claims 1-2, wherein the proxy server (22) implements a Proxy Call Session Control Function, P-CSCF.

4. The method of any of claims 1-3, wherein the access network information header field (34M) is a P-Access-Network-Info header field.

5. The method of any of claims 1-4, wherein the relay communication device (12) is a 5G Proximity Services, ProSe, user equipment to network, U2N, relay, and wherein the access network information header field (34M) includes a U2N-relay-ID parameter whose value is set to the identity (12-ID) of the relay communication device (12).

6. The method of any of claims 1-5, wherein the identity (12-ID) of the relay communication device (12) is a core network level identity available for an Internet Protocol, IP, Connectivity Access Network, CAN, session within which the session establishment request (30) is received.

7. The method of any of claims 1-6, wherein the identity (12-ID) of the relay communication device (12) is: a subscription permanent identifier, SlIPI; a subscription concealed identifier, SlICI;an International Mobile Subscription Identifier, IMSI; or a Mobile Station International Subscriber Directory Number, MSISDN.

8. The method of any of claims 1-7, wherein the access network information header field (34M) further indicates that the identity (12-ID) of the relay communication device (12) is provided by the IMS network (20).

9. The method of any of claims 1-8, wherein the modified session establishment request (30M) is forwarded to a server (24) that implements an emergency Call Session Control Function, E-CSCF.

10. The method of any of claims 1-9, wherein the access network information header field (34M) further indicates: that the session establishment request (30) was relayed via communication device relaying; and / or a location of the relay communication device (12) as provided by the remote communication device (14).

11. The method of claim 10, wherein the access network information header field (34M) includes: an access type parameter whose value indicates that the session establishment request (30) was relayed via communication device relaying; and / or a cell identity parameter whose value indicates the location of the relay communication device (12) in terms of an identity of a cell in which the relay communication device (12) is located.

12. The method of any of claims 1-11, wherein said obtaining comprises retrieving the identity (12-ID) of the relay communication device (12) from a Policy Control Function, PCF.

13. The method of any of claims 1-12, wherein said obtaining and modifying is performed responsive to determining: that the session establishment request (30) was relayed via communication device relaying; and that the session establishment request (30) as received indicates a location of the relay communication device (12) as provided by the remote communication device (14).

14. The method of any of claims 1-13, wherein the session establishment request (30) as received includes a preferred identity header field (32P) that indicates an identity (14-1 D) of the remote communication device (14), and wherein the session establishment request (30) as modified further includes an asserted identity header field (32A) that indicates the identity (14- ID) of the remote communication device (14) as indicated by the preferred identity header field (32 P).

15. The method of any of claims 1-14, wherein the relay communication device (12) is a 5G Proximity Services, ProSe, UE-to-Network relay, and / or wherein the remote communication device (14) is a 5G ProSe Remote UE.

16. A method performed by a server (24) in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20), the method comprising: receiving (500), by the server (24), a session establishment request (30) requesting establishment of an emergency call session for a remote communication device (14), wherein the session establishment request (30) indicates the session establishment request (30) was relayed via communication device relaying and includes an access network information header field (34M) that indicates an identity (12-ID) of a relay communication device (12) that relayed the session establishment request (30).

17. The method of claim 16, wherein the session establishment request (30) is a Session Initiation Protocol, SIP, INVITE request.

18. The method of any of claims 16-17, wherein the access network information header field (34M) is a P-Access- Network- Info header field.

19. The method of any of claims 16-18, wherein the relay communication device (12) is a 5G Proximity Services, ProSe, user equipment to network, U2N, relay, and wherein the access network information header field (34M) includes a U2N-relay-ID parameter whose value is set to the identity (12-ID) of the relay communication device (12).

20. The method of any of claims 16-19, wherein the identity (12-ID) of the relay communication device (12) is a core network level identity available for an Internet Protocol, IP, Connectivity Access Network, CAN, session within which the session establishment request (30) is received.

21. The method of any of claims 16-20, wherein the identity (12-1 D) of the relay communication device (12) is: a subscription permanent identifier, SlIPI; a subscription concealed identifier, SlICI; an International Mobile Subscription Identifier, IMSI; or a Mobile Station International Subscriber Directory Number, MSISDN.

22. The method of any of claims 16-21, wherein the access network information header field (34M) further indicates that the identity (12-ID) of the relay communication device (12) is provided by the IMS network (20).

23. The method of any of claims 16-22, wherein the relay communication device (12) provides communication device relaying via Layer 2 or Layer 3, and wherein the access network information header field (34M) indicates information about an access network providing Layer 2 or Layer 3 connectivity via which the IMS network (20) was accessed and includes a relay ID parameter whose value is set to the identity (12-ID) of the relay communication device (12).

24. The method of any of claims 16-23, wherein the access network information header field (34M) further indicates: that the session establishment request (30) was relayed via communication device relaying; and / or a location of the relay communication device (12) as provided by the remote communication device (14).

25. The method of claim 24, wherein the access network information header field (34M) includes: an access type parameter whose value indicates that the session establishment request (30) was relayed via communication device relaying; and / or a cell identity parameter whose value indicates the location of the relay communication device (12) in terms of an identity of a cell in which the relay communication device (12) is located.

26. The method of any of claims 16-25, wherein the session establishment request (30) further includes an asserted identity header field (32A) that indicates the identity (14-ID) of the remote communication device (14).

27. The method of any of claims 16-26, wherein the relay communication device (12) is a 5G Proximity Services, ProSe, UE-to-Network relay, and / or wherein the remote communication device (14) is a 5G ProSe Remote UE.

28. The method of any of claims 16-27, wherein the session establishment request (30) is received from a proxy server (22) that implements a Proxy Call Session Control Function, P- CSCF, and wherein the server (24) implements an emergency Call Session Control Function, E-CSCF.

29. The method of any of claims 16-28, wherein the session establishment request (30) indicates a location of the relay communication device (12) as provided by the remote communication device (14), and wherein the method further comprises transmitting, to a location server, a query to validate the location of the relay communication device (12) as provided by the remote communication device (14), wherein the query includes the session establishment request (30).

30. The method of claim 29, further comprising: receiving (510) a response to the query; and routing (520) the session establishment request (30) based on the response.

31. The method of claim 30, wherein the server (24) implements an emergency Call Session Control Function, E-CSCF, wherein the response indicates an address of a selected Public Safety Answering Point, PSAP, for the emergency call session, and wherein routing the session establishment request (30) comprises routing the session establishment request (30) towards the address of the selected PSAP.

32. The method of any of claims 16-27, wherein the session establishment request (30) is received from an emergency Call Session Control Function, E-CSCF, and wherein the server (24) implements a location retrieval function, LRF.

33. The method of any of claims 16-27 and 32, wherein the session establishment request (30) indicates a location of the relay communication device (12) as provided by the remote communication device (14), wherein the session establishment request (30) is received in a query to validate the location of the relay communication device (12) as provided by the remote communication device (14).

34. The method of claim 33, further comprising:validating (530) the location of the relay communication device (12) as provided by the remote communication device (14), by: obtaining (540) a location of the relay communication device (12) identified by the identity (12-ID); and comparing (550) the obtained location to the location of the relay communication as provided by the remote communication device (14); and transmitting (560) a response to the query based on said validating.

35. A proxy server (22) configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20), the proxy server (22) configured to: receive a session establishment request (30) from a remote communication device (14) requesting establishment of an emergency call session, wherein the session establishment request (30) indicates the session establishment request (30) was relayed via communication device relaying; obtain an identity (12-ID) of a relay communication device (12) that relayed the session establishment request (30); modify the session establishment request (30) to include an access network information header field (34M) that indicates the identity (12-ID) of the relay communication device (12); and forward the modified session establishment request (30M) to another server (24) in the IMS network (20).

36. The proxy server (22) of claim 35, configured to perform the method of any of claims 2- 15.

37. A server (24) configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20), the server (24) configured to: receive a session establishment request (30) requesting establishment of an emergency call session for a remote communication device (14), wherein the session establishment request (30) indicates the session establishment request (30) was relayed via communication device relaying and includes an access network information header field (34M) that indicates an identity (12-ID) of a relay communication device (12) that relayed the session establishment request (30).

38. The server (24) of claim 37, configured to perform the method of any of claims 17-34.

39. A computer program comprising instructions which, when executed by at least one processor of a proxy server (22), causes the proxy server (22) to perform the method of any of claims 1-15.

40. A computer program comprising instructions which, when executed by at least one processor of a server (24), causes the server (24) to perform the method of any of claims 16-34.

41. A carrier containing the computer program of any of claims 39-40, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

42. A proxy server (22) configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20), the proxy server (22) comprising: communication circuitry; and processing circuitry configured to: receive a session establishment request (30) from a remote communication device (14) requesting establishment of an emergency call session, wherein the session establishment request (30) indicates the session establishment request (30) was relayed via communication device relaying; obtain an identity (12-1 D) of a relay communication device (12) that relayed the session establishment request (30); modify the session establishment request (30) to include an access network information header field (34M) that indicates the identity (12-1 D) of the relay communication device (12); and forward the modified session establishment request (30M) to another server (24) in the IMS network (20).

43. The proxy server (22) of claim 42, the processing circuitry configured to perform the method of any of claims 2-15.

44. A server (24) configured for use in an Internet Protocol, IP, Multimedia Subsystem, IMS, network (20), the server (24) comprising: communication circuitry; and processing circuitry configured to receive a session establishment request (30) requesting establishment of an emergency call session for a remote communication device (14), wherein the session establishment request (30) indicates the session establishment request (30) was relayed via communicationdevice relaying and includes an access network information header field (34M) that indicates an identity (12-1 D) of a relay communication device (12) that relayed the session establishment request (30).

45. The server (24) of claim 44, the processing circuitry configured to perform the method of any of claims 17-34.

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