Patent Publication Number: US-11394454-B2

Title: Lawful intercept reporting in wireless networks using public safety relays

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/671,728 filed on Mar. 27, 2015, which to U.S. Provisional Patent Application No. 61/990,608, which was filed on May 8, 2014, and which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Wireless networks provide network connectivity to mobile communication devices, such as smart phones. The network connectivity may be provided through radio interfaces. Typically, the mobile devices connect to the wireless network through an access point that is part of the network infrastructure. For example, a device may connect to a cellular base station or a wireless local area network (WLAN) access point (e.g., a WiFi access point). 
     Some techniques may allow devices to establish direct communication paths with one another (e.g., without going through a cellular base station or WiFi access point). For example, devices that are located in proximity to one another may discover one another and subsequently establish direct communication paths with one another. In specifications published by the 3 rd  Generation Partnership Project (3GPP), direct communication between wireless devices may be referred to as “proximity services” (ProSe). ProSe communications can have a number of advantages, such as improved spectrum utilization, improved overall throughput and performance, and improved energy consumption. In the context of public safety services, ProSe communications can provide an important fallback public safety network that may function when a cellular network (e.g., a 3GPP cellular network) has failed or is unavailable. 
     A network, such as a 3GPP-based network, may include Lawful Interception (LI) functionality. Under LI, the network provider may enable Law Enforcement Agencies (LEAs) to intercept content and other related information corresponding to traffic of particular mobile devices. For lawful intercept, the target mobile device(s) may need to be identified. 
     In ProSe communications, a relay device, such as a mobile device acting as a relay device, may be used to couple another mobile device (such as one that is out of the coverage area of the cellular network) to the cellular network. Implementing lawful intercept in this situation can be problematic, however, as the mobile device that is to be targeted for lawful intercept may not be visible to the cellular network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals may designate like structural elements. Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. 
         FIG. 1  is a diagram of an example environment in which systems and/or methods described herein may be implemented. 
         FIG. 2  is a diagram of an example implementation of portions of the environment shown in  FIG. 1  in additional detail. 
         FIG. 3  is flow chart illustrating an example process for performing lawful intercept reporting. 
         FIG. 4  is a diagram illustrating a technique that may be used to authenticate a remote User Equipment (UE) without network involvement. 
         FIG. 5  is a diagram illustrating an example implementation of a system for performing lawful intercept reporting of identification information for a remote UE. 
         FIGS. 6 and 7  are diagrams illustrating examples of communication flows for performing lawful intercept reporting of identification information for a remote UE. 
         FIG. 8  is a diagram of example components of a device. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments in accordance with the present invention is defined by the appended claims and their equivalents. 
     Techniques described herein may enable Lawful Intercept (LI) services for User Equipment (UE) (e.g., smart phones or other mobile communication devices) in situations in which at least one UE is participating in ProSe services such that the UE is “indirectly” coupled to a cellular network via a relay device. As an example of this situation, a group of public safety personnel (e.g., firefighters) may be first responders at an accident. UEs of one or more members of the group may be out of the coverage range of the cellular network used by the group (e.g., some of the members may be indoors, in a tunnel, etc.). The members of the group may continue to communicate with one another and with the cellular network using ProSe communications services. In this scenario, the UE of one member of the group, which may be within the coverage range of the cellular network, may act as a relay device for other members of the group, which may be referred to as “remote UEs” herein, that are out of the coverage range. All members of the group may thus continue to communicate via the cellular network. 
     In some situations, such as in the case of Internet Protocol (IP) version 4 addressing (IPv4), the UE acting as the relay device may use Network Address Translation (NAT) techniques when relaying traffic. NAT may obscure visibility, from the standpoint of the cellular network, about which traffic flows correspond to the relay UE and which traffic flows correspond to the remote UEs. This can be problematic for the performance of lawful intercept services. 
     Consistent with aspects described herein, the relay device may assist in enabling lawful intercept by reporting, to a LI device associated with the cellular network, authenticated identities of the remote UEs and identification information that may allow the LI device to monitor traffic (and/or control statistics related to the traffic) associated with the remote UEs. The authentication of the remote UEs may be performed using a technique that does not require involvement of the cellular network. The identification information may include, for an IPv6 address, an IPv6 prefix. For IPv4 addressing, the identification information may include the public IPv4 address of the relay device and a port number assigned by the relay device. The techniques described herein, for implementing lawful intercept, may generally serve to minimize the impact on existing cellular networks, such as a 3GPP Evolved Packet System (EPS) wireless network. 
     In one implementation consistent with aspects described herein, a UE may include processing circuitry to: connect with a second UE using a first radio interface that is not connected to a cellular network; connect with the cellular network using a second radio interface; authenticate, via the first radio interface, an identity of the second UE received from the second UE; and act as a wireless relay, to the cellular network, for the second UE to forward communications from the second UE to the wireless network. 
     Additionally or alternatively, the UE may act as a wireless relay by performing Layer-3 forwarding of IP packets between the second UE and the cellular network. Additionally or alternatively, the first radio interface may include a WLAN direct connection. Additionally or alternatively, the first radio interface may include an E-UTRA direct connection. 
     Additionally or alternatively, the authentication may be performed based on a digital signature received from the second UE, without requiring, during the authentication of the identity of the second UE, communications over the cellular network. The authentication may be performed using ECCSI techniques or certificate based techniques in which the authentication does not require real-time communication with a common node of trust. 
     Additionally or alternatively, the UE may report, to a lawful intercept device associated with the cellular network, identification information and the authenticated identity of the second UE. Additionally or alternatively, the identification information nay include an IPv4 address and a port number assigned to the UE as part of a NAT procedure; or an Internet Protocol version 6 (IPv6) address prefix. Additionally or alternatively, the lawful intercept device may include a device operating in the user plane of the wireless network, the processing circuitry may be further to: report the identification information and the authenticated identity of the second UE via a user plane HTTP. The lawful intercept device may include a MME or PGW in a control plane of the wireless network. 
     In another implementation consistent with aspects described herein, a UE may include a first radio interface; a second radio interface; a computer-readable medium to store processor executable instructions; and processing circuitry to execute the processor executable instructions to: connect, via the first radio interface, with a second UE, in proximity of the UE, to ProSe to the second UE, authenticate an identity of the second UE received, via the first radio interface, from the second UE, relay communications received from the second UE, over the first radio interface, to a wireless network that is connected to the UE via the second radio interface, and report, to a lawful intercept entity associated with the wireless network, identification information that identifies network traffic of the second UE. 
     Additionally or alternatively, the lawful intercept entity may include a device operating in a user plane of the wireless network, the reporting further including reporting the identification information via a user plane protocol. 
     In another implementation consistent with aspects described herein, a method, implemented at a relay device, may include authenticating, by the relay device, an identity of a remote UE that is connected to the relay device via a direct radio connection, the authenticating including authenticating an identity of the remote UE; and reporting, by the relay device and to a lawful intercept entity associated with cellular wireless network to which the relay device is connected: an IPv6 address prefix associated with the remote UE, or an IPv4 address and a port number assigned to the remote UE as part of a NAT procedure; and the authenticated identity of the remote UE. 
     Additionally or alternatively, the method may include relaying traffic, associated with the remote UE, to the cellular wireless network. Additionally or alternatively, the reporting, to the lawful intercept entity, may be performed via Non-Access Stratum (NAS) layer signaling. 
     In another implementation consistent with aspects described herein, a relay device may include means for authenticating an identity of a remote UE that is connected to the relay device via a direct radio connection, the authenticating including authenticating an identity of the remote UE; and means for reporting, to a lawful intercept entity associated with cellular wireless network to which the relay device is connected: an IPv6 address prefix associated with the remote UE, or an IPv4 address and a port number assigned to the remote UE as part of a NAT procedure; and the authenticated identity of the remote UE. 
       FIG. 1  is a diagram of an example environment  100  in which systems and/or methods described herein may be implemented. As illustrated, environment  100  may include relay device  110 , User Equipment (UE) devices  112 ,  114 , and  116 , wireless network  120 , public safety application server  130 , and law enforcement agency (LEA)  140 . UEs  112 ,  114 , and  116  may generally refer to any wireless communication devices, such as a mobile telephone, smart phone, tablet computing device, laptop computing device, etc., that is capable of communicating wirelessly with wireless network  120 . Relay device  110  may also be a UE device, such as a UE device that is structurally similar or identical to UEs  112 ,  114 , or  116 . For clarity, a UE, when operating to perform functionality of a relay device, will be referred to herein as a “relay device” (i.e., relay device  110 ). Similarly, remote UEs  114  and  116  may be structurally similar or equivalent to UE  112 . A UE that is communicating through relay device  110  to obtain network connectivity will be referred to herein as a “remote UE” (e.g., remote UE  114  or  116 ). 
     Relay device  110 , UE  112 , and remote UEs  114  and  116  may each include a portable computing and communication devices, such as a personal digital assistant (PDA), a smart phone, a cellular phone, a laptop computer with connectivity to a cellular wireless network, a tablet computer, etc. Relay device  110 , UE  112 , and remote UEs  114  and  116  may also include non-portable computing devices, such as desktop computers, consumer or business appliances, or other devices that have the ability to connect to wireless network  120 . Relay device  110 , UE  112 , and remote UEs  114  and  116  may connect, through a radio link, to wireless network  120 . 
     Relay device  110 , UE  112 , and remote UEs  114  and  116  may include radio interfaces that allow devices  110 - 116  to connect wirelessly to wireless network  120 , to one another, and/or to other devices. For example, relay device  110 , UE  112 , and remote UEs  114  and  116  may each include a first radio transceiver to connect to a cellular access network, such as a 3GPP/Long Term Evolution (LTE) based-network, and a second radio transceiver to implement WiFi-based communications (e.g., Institute of Electrical and Electronics Engineers&#39; (IEEE) 802.11-based communications). Relay device  110 , UE  112 , and remote UEs  114  and  116  may connect directly to one another using ProSe services implemented over a direct communication path (e.g., via a WLAN connection, such as a WiFi direct path, or through an Evolved Universal Terrestrial Radio Access (E-UTRA) direct communication path that does not use wireless network  120 ). Alternatively or additionally, when within the coverage area of wireless network  120 , relay device  110  and UE  112  may communicate with wireless network  120 . 
     Wireless network  120  may include one or more networks that provide wireless network connectivity to mobile devices  110 . For example, wireless network  120  may represent a wireless network that provides cellular wireless coverage. In some implementations, wireless network  120  may be associated with a LTE network. One example implementation of wireless network  120  in conjunction with a relay device is illustrated, in additional detail, in  FIG. 2 . 
     Public safety application server  130  may include one or more computation and communication devices that provide services to public safety personnel and/or organizations. For example, public safety application server  130  may provide services relating to ProSe communications between public safety personnel, such as services relating to assisting in the identification of UEs in physical proximity with one another and/or the enablement of optimized communications between the UEs. As another example, public safety application server  130  may function to enable group calling between groups of public safety personnel, such as one-to-many calling or the dispatching of public safety personnel to emergency situations. Although shown as being implemented outside of wireless network  120 , in practice, public safety application server may alternatively or additionally be implemented within wireless network  120 . 
     LEA  140  may represent an entity, such as a law enforcement entity, that may obtain network communications data pursuant to lawful authority for the purpose of analysis or evidence. The obtained data may include, for example, signaling or network management information or, alternatively or additionally, the substantive content of communications. The signaling/network management information may be referred to as Intercept Related Information (IRI) herein, and the substantive content may be referred to as Content of Communications (CC) herein. In one implementation, LEA  140  may transmit an intercept request to wireless network  120 . The intercept request may include authentication information validating that the request is a lawful request and information identifying the parties to which the request is to be applied. In response, wireless network  120  may intercept the indicated communications and provide the intercepted information to LEA  140 . 
       FIG. 2  is a diagram of an example implementation of portions of environment  100  in additional detail. In particular, in  FIG. 2 , an example implementation of wireless network  120  is illustrated in the context of a relay device and a remote UE communicating using ProSe techniques. 
     In  FIG. 2 , wireless network  120  may include an EPS that includes a LTE network and/or an evolved packet core (EPC) network that operates based on a 3GPP wireless communication standard. The LTE network may be, or may include, a radio access network that includes one or more base stations, some or all of which may take the form of an eNodeB (eNB)  220 , via which relay device  110  may communicate with the EPC network. The EPC network may include one or more serving gateways (SGWs)  225 , mobility management entities (MMEs)  230 , and/or packet data network gateways (PGWs)  235 , and may enable UEs to communicate with an external network. Additionally, wireless network  120  may include LI function  240  and home subscriber server (HSS)  245 . 
     eNB  220  may include one or more network devices that receive, process, and/or transmit traffic destined for and/or received from relay device  110 . eNB  220  may provide the wireless (i.e., radio) interface with relay device  110 . 
     SGW  225  may include one or more network devices that route data of a traffic flow. SGW  225  may aggregate traffic received from one or more base stations  220  and may send the aggregated traffic to an external network via PGW  235 . SGW  225  may also act as a mobility anchor during inter-base station handovers. 
     MME  230  may include one or more computation and communication devices that act as a control-node for eNB  220  and/or other devices that provide the air interface for wireless network  120 . For example, MME  230  may perform operations to register relay device  110  with wireless network  120 , to establish bearer channels (e.g., traffic flows) associated with a session with relay device  110 , to hand off relay device  110  to another network, and/or to perform other operations. MME  230  may perform policing operations on traffic destined for and/or received from relay device  110 . 
     PGW  235  may include one or more network devices that may aggregate traffic received from one or more SGWs  225 , and may send the aggregated traffic to an external network PGW  235  may also, or alternatively, receive traffic from the external network and may send the traffic toward relay device  110  via SGW  225 , and/or base station  220 . 
     LI function  240  may represent functionality, implemented by one or more network devices, to perform lawful intercept. Based on identification information for a UE, LI function  240  may capture and report IRI and/or CC data relating to the UE. LI function  240  may report the captured data to an authorized entity, such as LEA  140 . LI function  240  may be implemented as functionality that is part of, for example, MME  230 , PGW  235 , HSS  245 , public safety application server  130 , or as part of another network element. Alternatively or additionally, LI function  240  may be implemented by a dedicated network device. 
     HSS  245  may include one or more devices that may manage, update, and/or store, in a memory associated with HSS  245 , profile information associated with a subscriber. The profile information may identify applications and/or services that are permitted for and/or accessible by the subscriber; a mobile directory number (MDN) associated with the subscriber; bandwidth or data rate thresholds associated with the applications and/or services; and/or other information. The subscriber may be associated with UEs  110 - 116 . Additionally, or alternatively, HSS  245  may perform authentication, authorization, and/or accounting operations associated with the subscriber and/or a communication session with UEs  110 - 116 . 
     A number of communication interfaces, which may include standardized 3GPP interfaces, are illustrated in  FIG. 2 . For example, remote UE  114 , which may be out of network with respect to connectivity to wireless network  120 , may directly communicate with relay device  110  (e.g., using an E-UTRA direct connection) using the PC5 interface. The PC5 interface may generally be used for UE to UE (e.g., remote UE to relay device) control and user plane communications. Relay device  110  may communicate with eNB  220  using the LTE-Uu interface. Relay device  110  may perform a mapping between bearers over the PC5 and Uu interfaces. Additionally, remote UE  114  may not maintain a signaling connection to wireless network  120 . Instead, relay device  110  may be responsible for the establishment and maintenance of the EPS bearers associated with wireless network  120 . 
     In operation, relay device  110  may operate as a Layer-3 device (e.g., relay device  110  may behave as a router that performs Layer-3 forwarding of IP packets) with respect to performing relay functions for remote UE  114 . When IPv6 addressing is used on the PC5 interface, relay device  110  may perform prefix delegation to assign an IPv6 prefix to remote UE  114 . The assigned IPv6 prefix may subsequently be used by wireless network  120  to identify communications associated with remote UE  114 . IPv6 prefix delegation is described in, for example, in the 3GPP technical specification (TS) 23.303 v.12.0.0. 
     In some implementations, the PC5 interface may use IPv4 addressing. In this situation, relay device  110  may act as a NAT device and may assign UE  114  a private IPv4 address. When communicating with wireless network  120 , relay device  110  may assign a particular port value to relay device  110 , and may use the public IPv4 address of relay device  110  (i.e., the IPv4 address seen by wireless network  120 ), in combination with the particular port value, to handle network traffic associated with remote UE  114 . 
     As will be described in more detail below, to enable lawful intercept of traffic associated with remote UE  114 , relay device  110  may authenticate remote UE  114  using an authentication technique that does not require real-time signaling over wireless network  120 . In other words, relay device  110  may authenticate the identity of remote UE  114  using out-of-network communications (i.e., over the PC5 interface) between remote UE  114  and relay device  110 . Relay device  110  may then report the authenticated identity of remote UE  114  along with the assigned IPv6 prefix (for IPv6 communications) or the public IPv4 address and port value (for IPv4 communications) to wireless network  120  (e.g., to LI function  240 ). LI function  240  may subsequently perform lawful intercept of communications associated with remote UE  114 , such as by reporting CC or IRI information relating to the communications. The operations performed by relay device  110  may generally operate in a manner that minimizes the impact on existing 3GPP systems. 
       FIG. 3  is flow chart illustrating, at a high level, an example process  300  for performing lawful intercept reporting. Process  300  may be implemented, for example, by relay device  110 . 
     Process  300  may include authentication, by relay device  110 , of a remote UE (block  310 ). The authentication may be performed without real-time involvement of wireless network  120 . For example, the authentication may be performed between relay device  110  and remote UE  114  via the PC5 interface. In some implementations, relay device  110  and remote UE  114  may have been previously provisioned (potentially using wireless network  120 ) to support the authentication. Various techniques to implement the authentication will be described in more detail below. 
     Process  300  may further include reporting, via the user plane or control plane of the wireless network (i.e., wireless network  120 ), the authenticated public identity of the remote UE and identification information for the authenticated remote UE (block  320 ). For example, relay device  110  may, either in response to an explicit request from LI function  240  (or from another network element) or at another time (e.g., based on successful authentication of a remote UE), transmit the identification information for remote UE  114  to wireless network  120 . Relay device  110  may also transmit the authenticated identity of remote UE  114  (e.g., a digital signature received from UE  114  as part of the authentication process). The identification information may be transmitted to LI function  240  or to another network element to enable lawful intercept reporting to be performed by wireless network  120 . The identification information may include information needed by wireless network  120  to identify traffic corresponding to remote UE  114 . As mentioned previously, in the case of IPv6 traffic, the identification information may include the IPv6 prefix assigned to remote UE  214 . In the case of IPv4 traffic, the identification information may include the IPv4 public address of relay device  110  and the port number assigned to remote UE  114  by relay device  110 . 
     Relay device  110 , when reporting the identification information via the user plane, may perform the reporting using an appropriate protocol, such as hypertext transfer protocol (HTTP). Reporting via the user plane may be performed when LI function  240  is reachable via user plane traffic, such as when LI function is implemented as part of a ProSe service implemented by public safety application server  130 . In other situations, such as when LI function  240  is implemented within MME  230 , control plane signaling, such as Non-Access Stratum (NAS) layer signaling, may be used to provide the identification information to LI function  240  (e.g., to MME  230 ). 
       FIG. 4  is a diagram illustrating one possible technique that may be used to authenticate a remote UE without network involvement. In  FIG. 4 , the Elliptic Curve-Based Certificateless Signatures for Identity-Based Encryption (ECCSI) technique is illustrated. ECCSI is a known technique that is described in more detail in Internet Engineering Task Force (IETF) Request For Comments (RFC) 6507. 
     In  FIG. 4 , a Key Management Service (KMS), Signer, and Verifier are illustrated. In the context of  FIGS. 1 and 2 , the Signer may correspond to remote UE  114  and the Verifier may correspond to relay device  110 . The KMS may correspond to a trusted authentication service, such as one implemented by a device associated with wireless network  120  or a device associated with an external network. For ECCSI authentication, the Signer and Verifier, at some point, may need to be provisioned with data received from the KMS. The provisioning may be performed, however, at some point prior to the performance of the ECCSI authentication (e.g., when the Signer and Verifier are within the coverage range of wireless network  120 ). 
     As illustrated in  FIG. 4 , the KMS may maintain a KMS Public Authentication Key (KPAK) that may be known by all users. The KPAK may be stored by the Signer and Verifier. Additionally, as part of the initial provisioning, the Signer may obtain a Secret Signing Key (SSK) and Public Validation Token (PVT) from the KMS. Further, every user may be associated with a publicly known identity. In  FIG. 4 , the publicly known identity of the Signer is illustrated as ID_s. 
     For an authentication operation, the Signer may combine the KPAK, the SSK, the PVT, and the message (M) that is to be signed, in the manner specified in RFC 6507 (i.e., in the manner consistent with the ECCSI technique). The resultant signature (SIGN) may be transmitted, over the PC5 interface, with the message (M) and the public identity of the Signer (ID_s), to the Verifier. Upon reception, the Verifier may apply the ECCSI technique, based on the KPAK, the received message (M), the public identity of the Signer (ID_s), and the signature (SIGN), to authenticate the Signer. With ECCSI, a single communication from the Signer to the Verifier may be used to authenticate the Signer. 
     As an alternative to using ECCSI-based authentication, other authentication techniques may be used authenticate the remote UE without real-time network involvement. For example, digital certificate-based techniques may be used. For example, a certificate, such as a certificate corresponding to the ITU-T (ITU Telecommunication Standardization Sector) X.509 standard, and issued by a trusted certificate authority, may be stored/provisioned at relay device  110  and/or remote UE  114 . Authentication may be based on an exchange of the certificates. In either the ECCSI-based authentication or the certificate-based authentication, authentication may be performed without real-time communication with a common note of trust (i.e., without real-time adjudication with KMS or a trusted certificate server). 
       FIG. 5  is a diagram illustrating an example implementation of a system  500  for performing lawful intercept reporting of identification information for a remote UE. In this example, ECCSI-based authentication is used. The system of  FIG. 5  is similar to that shown in  FIG. 2 . Additionally, as shown, system  500  may include key management server (KMS)  510 , which may implement an ECCSI key management device. Additionally, in system  500 , LI function  240  is illustrated as being performed by ProSe component  520  of public application server  130 . ProSe component  520  may implement functionality related to the enablement of ProSe services for UEs used by public safety personnel. ProSe communications between relay device  110  and remote UE  114  may be performed using ProSe applications (ProSe App) that are implemented by relay device  110  and remote UE  114 . 
     A number of communication interfaces, between the various components of system  500 , are illustrated in  FIG. 5 . The communication interfaces may include 3GPP standardized interfaces. As illustrated, the interfaces may include: a PC5 interface between relay device  110  and remote UE  114 , a PC3 interface between relay device  110  and ProSe component  520 , a Uu interface between relay device  110  and eNB  220 , a S1-U interface between eNB  220  and SGW/PGW  225 / 235 , a S1-U interface between eNB  220  and MME  230 , a SGi interface between SGW/PGW  225 / 235  and ProSe component  520 , a S11 interface between SGW/PGW  225 / 235  and MME  230 , and a S6a interface between MME  230  and HSS  245 . 
       FIG. 6  is a diagram illustrating an example of a communication flow  600 , which may be performed in system  500 , for performing lawful intercept reporting of identification information for a remote UE in system  500 . For communication flow  600 , the lawful intercept reporting may be performed via the user plane of wireless network  120 . The operations of communication flow  600  will be discussed with reference to  FIG. 5 . 
     Relay device  110 , which may be within the coverage range of wireless network  120 , may initially attach to wireless network  120  (at  610 , “EPS Attach”). Attaching to wireless network  120  may be performed using existing techniques. At some point, remote UE  114  and relay device  110  may discover one another for the purpose of ProSe communications (at  615 , “Relay Discovery”). For example, using ProSe Direct Discovery, as defined in 3GPP TS 23.303, v12.0.0, a UE may detect and identify another UE in proximity using E-UTRA direct radio signals. 
     Remote UE  114  may be authenticated by relay device  110  (at  620 , “Remote UE Authentication Without Network Involvement”). As previously mentioned, the authentication may be made without the involvement of wireless network  120  (e.g., based only on communications over the PC5 interface between relay device  110  and remote UE  114 ). For example, in one implementation, authentication may be performed using ECCSI-based authentication techniques. In this situation, and with reference to  FIG. 4 , remote UE  114  and relay device  110  may act in the role of Signer and Verifier, respectively. Alternatively, as another example, authentication may be performed using certificate-based authentication techniques. In either situation, provisioning may be performed at an earlier time such as during initial provisioning of the UEs or when the UEs are attached to wireless network  120 . 
     Authentication that does not require network involvement may have the benefit of not having to support the RADIUS or Diameter protocol in relay device  110 . This can be advantageous as a public safety UE may be expected to occasionally operate as relay device  110 . 
     Relay device  110  may assign an IP address to remote UE  114  (at  625 , “IP Address Assignment”). When IPv6 addressing is being used, relay device  110  may assign an IPv6 prefix to remote UE  114  using IP prefix delegation (e.g., as described in 3GPP TS 23.303 v12.0.0). Alternatively, when IPv4 addressing is used, relay device  110  may assign a private IPv4 address to remote UE  114 . When relaying communications to network  120 , relay device  110  may translate the private IPv4 address to the public IPv4 address of relay device  110  along with a port number assigned, by relay device  110 , to remote UE  114 . 
     At some point, relay device  110  may report, via the user plane, the identification information of remote UE  114  (at  630 , “LI Reporting via User Plane”). In this implementation, the network device, corresponding to the device performing the lawful intercept function (i.e., LI function  240 ), is reachable via user plane traffic. For example, the network device associated with LI function  240  may correspond to public safety application server  130  that implements ProSe component  520 , or another network device reachable via the user plane of wireless network  120 . An appropriate user plane protocol, such as HTTP, may be used to report the identification information. In the example of  FIG. 5 , for instance, the PC3 interface, such as via HTTP over the PC3 interface, may be used to report the identification information to LI function  240 . In some implementations, the authenticated public identify of the remote UE  114  (e.g., ID_s in the description of  FIG. 4 ) may also be reported. 
     As previously mentioned, the identification information may include information needed by wireless network  120  to identify traffic corresponding to remote UE  114 . In the case of IPv6 traffic, the identification information may include the IPv6 prefix assigned to remote UE  214 . In the case of IPv4 traffic, the identification information may include IPv4 public address of relay device  110  and the port number assigned to remote UE  114  by relay device  110 . 
     In response to receiving the identification information, or at some later time, the device performing the lawful intercept function may obtain and/or analyze communications from remote UE  114 , such as, for user plane traffic, the content of the communications. The content of the communications may be transmitted to law enforcement agency  140 . 
       FIG. 7  is a diagram illustrating another example of a communication flow  700 , which may be performed in system  500 , for performing lawful intercept reporting of identification information for a remote UE in system  500 . For communication flow  700 , the lawful intercept reporting may be performed via the control plane of wireless network  120 . 
     A number of the communications shown in  FIG. 7  are similar to the corresponding communications shown in  FIG. 6 . In particular, communications  710 - 725  correspond to communications  610 - 625 , respectively. For brevity, the descriptions of these communications will not be repeated herein. 
     At some point, relay device  110  may report, via the control plane, the identification information of remote UE  114  (at  730 , “LI Reporting via Control Plane”). In this implementation, the network device, corresponding to the device performing the lawful intercept function (i.e., LI function  240 ), is reachable via user control traffic. For example, the network device may correspond to MME  230  or PGW  235 , or another network device reachable via the control plane of wireless network  120 . The reporting may be performed via NAS signaling. 
     In one implementation, the NAS notification procedure, as defined in 3GPP TS 24.301, may be used. In some 3GPP network implementations, however, the NAS notification procedure may only be implemented by the network (and not by relay device  110 ). In these situations, lawful intercept reporting via the control plane may be performed by one or more of: (1) a modified NAS notification procedure in which initiation by a UE is permissible; or (2) overloading of an existing UE-initiated NAS procedure, such as a modification to the NAS UE Requested Bearer Resource Modification. Alternatively or additionally, a new NAS procedure, specific to lawful intercept reporting, may be defined. 
     In some network implementations, LI function  240  may be implemented in PGW  235 . In this implementation, lawful intercept reporting may be performed either indirectly by causing the MME  230  to forward the lawful intercept reporting, or directly using the Protocol Configuration Options (PCO) parameter that is sent by remote device  110  (e.g., by using the NAS Requested Bearer Resource Modification procedure). The PCO is a component of a number of NAS messages, such as a PDN Connectivity Request, an Activate Default EPS Bearer Context Request, and an “Activate Default EPS Bearer Context Accept message. 
     In both communications  630  and  730 , the reported information, associated with remote UE  114 , may be encoded in a number of formats, such as a format compatible with the guidelines specified in RFC 6509. As an example, the identification information and/or the authenticated public identity may be a concatenation of a fixed part and a varying part. The fixed part may be in the form of, for example, an International Mobile Subscriber Identity (IMSI), a Session Initiation Protocol (SIP) Uniform Resource Identifier (URI), a terminal equipment list (TEL) URI, and/or other user@domain types of URI. The varying part may include, for example, a timestamp value. 
       FIG. 8  is a diagram of example components of a device  800 . Each of the devices illustrated in  FIGS. 1, 2, 4 , and/or  5  and may include one or more devices  800 . Device  800  may include bus  810 , processor  820 , memory  830 , input component  840 , output component  850 , and communication interface  860 . In another implementation, device  800  may include additional, fewer, different, or differently arranged components. 
     Bus  810  may include one or more communication paths that permit communication among the components of device  800 . Processor  820  may include a processor, microprocessor, or processing logic that may interpret and execute instructions. Memory  830  may include any type of dynamic storage device that may store information and instructions for execution by processor  820 , and/or any type of non-volatile storage device that may store information for use by processor  820 . 
     Input component  840  may include a mechanism that permits an operator to input information to device  800 , such as a keyboard, a keypad, a button, a switch, etc. Output component  850  may include a mechanism that outputs information to the operator, such as a display, a speaker, one or more light emitting diodes (LEDs), etc. 
     Communication interface  860  may include any transceiver-like mechanism that enables device  800  to communicate with other devices and/or systems. For example, communication interface  860  may include an Ethernet interface, an optical interface, a coaxial interface, or the like. Communication interface  860  may include a wireless communication device, such as an infrared (IR) receiver, a cellular radio, a Bluetooth radio, or the like. The wireless communication device may be coupled to an external device, such as a remote control, a wireless keyboard, a mobile telephone, etc. In some embodiments, device  800  may include more than one communication interface  860 . For instance, device  800  may include an optical interface and an Ethernet interface. 
     Device  800  may perform certain operations described above. Device  800  may perform these operations in response to processor  820  executing software instructions stored in a computer-readable medium, such as memory  830 . A computer-readable medium may be defined as a non-transitory memory device. A memory device may include space within a single physical memory device or spread across multiple physical memory devices. The software instructions may be read into memory  830  from another computer-readable medium or from another device. The software instructions stored in memory  830  may cause processor  820  to perform processes described herein. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement processes described herein. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software. 
     In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense. 
     For example, while a series of blocks have been described with regard to  FIG. 3 , the order of the blocks may be modified in other implementations. Further, non-dependent blocks may be performed in parallel. Similarly, while a series of communications have been described with regard to  FIGS. 6 and 7 , the order of the communications may potentially be modified in other implementations. 
     It will be apparent that example aspects, as described above, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement these aspects should not be construed as limiting. Thus, the operation and behavior of the aspects were described without reference to the specific software code—it being understood that software and control hardware could be designed to implement the aspects based on the description herein. 
     Further, certain portions of the invention may be implemented as “logic” that performs one or more functions. This logic may include hardware, such as an ASIC or a FPGA, or a combination of hardware and software. 
     Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the invention. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. 
     No element, act, or instruction used in the present application should be construed as critical or essential to the invention unless explicitly described as such. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.