EP4690866A1 - Wtru-to-wtru relay discovery announcement scheduling - Google Patents

Abstract

A first wireless transmit/receive unit (WTRU) may include one or more processors. The first WTRU may be configured to determine that a relay service code (RSC) supports announcement scheduling assistance, send a first relay discovery announcement message to one or more second WTRUs based on the determination that the RSC supports announcement scheduling assistance, receive a relay discovery message from a second WTRU of the one or more second WTRUs, indicate the RSC and/or a direct discovery set of the second WTRU, determine that the received relay discovery message from the second WTRU is compliant with the announcement timing information, and/or send a second relay discovery announcement message to the second WTRU based on the determination that the received relay discovery message is compliant with the announcement timing information.

Description

WTRU-TO-WTRU RELAY DISCOVERY ANNOUNCEMENT SCHEDULING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States Provisional Application No. 63/457,944 filed on April 7, 2023, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] Proximity services (ProSe) may include one or more discovery security techniques. For example, a direct discovery security procedure and WTRU-to-network discovery security procedure may be employed. Restricted discovery messages may be protected, e.g., for integrity, confidentiality and/or from replay using security material respectively associated with a ProSe restricted code and/or relay service code (RSC). The protections against replay may be performed using time based mechanisms (e.g., UTC-time based mechanism), for example, to ensure the freshness of the discovery message protection.

[0003] For direct discovery, a wireless transmit/receive unit (WTRU) may be provided with security material associated with a ProSe restricted code by a direct discovery name management function (DDNMF). For WTRU-to-network discovery the WTRU/Relay may be provided with security material associated with an RSC, e.g., by a DDNMF and/or a policy control function (PCF) or a ProSe key management function (PKMF).

SUMMARY

[0004] A first wireless transmit/receive unit (WTRU) may include one or more processors. The first WTRU may be configured to determine that a relay service code (RSC) supports announcement scheduling assistance. The first WTRU may send a first relay discovery announcement message to one or more second WTRUs based on the determination that the RSC supports announcement scheduling assistance. The first relay discovery announcement message may indicate the RSC and announcement timing information. The first WTRU may receive a relay discovery message from a second WTRU of the one or more second WTRUs. The relay discovery message may indicate the RSC and/or a direct discovery set of the second WTRU. The first WTRU may determine that the received relay discovery message from the second WTRU is compliant with the announcement timing information. The WTRU may send a second relay discovery announcement message to the one or more second WTRUs based on the determination that the received relay discovery message is compliant with the announcement timing information. The second relay discovery announcement message may indicate the direct discovery set of the second WTRU.

[0005] The first relay discovery announcement message and the second relay discovery announcement message may be WTRU-to-WTRU relay discovery announcement messages. The first relay discovery announcement message may indicate a relay user information ID.

[0006] Each of the one or more second WTRUs may be an announcing end WTRU and/or a monitoring end WTRU.

[0007] The received relay discovery message may be a protected relay discovery message. The direct discovery set may be a protected direct discovery set.

[0008] The announcement timing information may include one or more of a time window, an offset, a period for future announcements, and/or a periodicity of announcements. The relay discovery message may be determined to be compliant with the announcement timing information when the relay discovery message is received within one or more of the time window, the offset, and/or the period for future announcements. The first WTRU may discard the received relay discovery message from the second WTRU on condition that the received relay discovery message does not comply with the announcement timing information. The received relay discovery message may not comply with the announcement timing information when the received relay discovery message is received at a time that is outside the time window, outside the offset, and/or outside the period for future announcements.

[0009] The second relay discovery announcement message may include respective RSCs and/or respective direct discovery sets of the one or more second WTRUs.

BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0011] FIG. 1 B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0012] FIG. 1 C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0013] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0014] FIG. 2 illustrates an example proximity service (ProSe) for a WTRU-to-WTRU relay discovery with model A.

[0015] FIG. 3 illustrates an example relay discovery message protection using a first approach.

[0016] FIG. 4 illustrates another example relay discovery message protection using a second approach.

[0017] FIG. 5 illustrates an example ProSe WTRU-to-WTRU relay Model A discovery.

DETAILED DESCRIPTION

[0018] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0019] As shown in FIG. 1 A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a CN 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and/or a “STA”, may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscriptionbased unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a headmounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU.

[0020] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements. [0021] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e. , one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0022] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0023] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA). [0024] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E- UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0025] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., a eNB and a gNB).

[0027] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1 X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0028] The base station 114b in FIG. 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 11 b may not be required to access the Internet 110 via the CN 106/115.

[0029] The RAN 104/113 may be in communication with the CN 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which may be utilizing a NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E- UTRA, or WiFi radio technology.

[0030] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104/113 or a different RAT. [0031] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1 A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0032] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and/or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment. [0033] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0034] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive I R, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0035] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0036] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0037] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic lightemitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), readonly memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown). [0038] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li- ion), etc.), solar cells, fuel cells, and the like.

[0039] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0040] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.

[0041] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a halfduplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0042] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0043] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

[0044] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0045] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0046] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.

[0047] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0048] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0049] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0050] Although the WTRU is described in FIGS. 1A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0051] In representative embodiments, the other network 112 may be a WLAN.

[0052] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to-peer traffic. The peer-to- peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11 e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[0053] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0054] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0055]Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0056] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 n, and 802.11 ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0057] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available. [0058] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0059] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0060] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and/or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c). [0061] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0062] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and/or a non-standalone configuration.

In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0063] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0064] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator. [0065] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and/or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

[0066] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a U PF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0067] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like. [0068] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0069] In view of Figures 1 A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions. [0070] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may perform testing using over-the-air wireless communications.

[0071] The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.

[0072] Wireless communication between one or more wireless transmit/receive units (WTRUs) and a network are considered herein.

[0073] Proximity service (ProSe) discovery security may be performed. Direct and WTRU-to-Network Discovery Security procedures may be used. For example, restricted discovery messages may be protected for integrity, confidentiality and from replay using security material respectively associated with a ProSe restricted code and relay service code (RSC). The protection against replay may be done using universal time coordinated (UTC)-time based mechanism to ensure the freshness of the discovery message protection.

[0074] For direct discovery, the WTRU may be provided with security material associated with a ProSe restricted code by a direct discovery name management function (DDNMF). For WTRU-to-network discovery the WTRU/Relay may be provided with security material associated with an RSC by a DDNMF or a policy control function (PCF) or a ProSe key management function (PKMF).

[0075] WTRU-to-WTRU relay discovery procedure 200 may be performed in association with the WTRU-to-WTRU relay discovery with Model A, as illustrated in FIG. 2. The WTRU-to-WTRU relay discovery procedure 200 may include a 5G ProSe WTRU-to- WTRU relay 202, and 5G ProSe end WTRUs 204 and 206. The 5G ProSe end WTRUs 204 and 206 may each be a monitoring WTRU.

[0076] At 208, the WTRU-to-WTRU relay 202 may discover other WTRUs e.g., the 5G ProSe end WTRUs 204 and 206) in proximity. At 210, the WTRU-to-WTRU relay 202 may send an announcement message that includes information about certain WTRUs e.g., end WTRUs 204 and 206) that were previously discovered or connected to the relay 202. [0077] The potential security requirements for WTRU-to-WTRU relay discovery may include the protection of discovery messages for WTRU-to-WTRU relay discovery, and/or the protection of privacy sensitive information of source WTRU and target WTRU during WTRU-to-WTRU relay discovery procedure.

[0078] One or more main techniques may be considered to address these requirements. For example, certain techniques may use a single key set associated with RSC, for example, to protect the discovery message that includes the WTRU-to-WTRU discovery set (e.g., RSC, user information) and direct discovery sets (e.g., user information ID of end WTRUs). Both the relay and the end WTRU may be provisioned with the security material associated with the RSC to properly exchange and process the security of the relay discovery message.

[0079] An example process 300 of relay discovery message protection using a first approach may be illustrated in FIG. 3. The relay discovery message may be a WTRU- to-WTRU relay discovery message 302. The WTRU-to-WTRU relay discovery message 302 may include a message type 304 (e.g., announcement), a UTC-based counter least significant bits (LSB) 306, a message integrity code (MIC) 308, a WTRU-to-WTRU relay information 310, and/or direct discovery sets 320 and 322. The direct discovery set 320 may include end WTRU 312 information (e.g., user information ID). The direct discovery set 322 may include end WTRU 314 information (e.g., user information ID). The MIC 308 may be computed for the integrity protection of the message using an integrity key. The part of the message with WTRU-to-WTRU relay information 310 and end WTRUs information element 312 and 314 may be encrypted using a confidentiality key. The UTC-based counter may be used on both integrity and confidentiality computation to guarantee freshness of the protection and protect against replay attacks. The UTC- based counter used by WTRUs internally may be encoded as the 32 most significant bits of UTC time. The parameter sent in the message by the Announcing WTRU may carry the four least significant bits (LSB) of the UTC-based counter 306. It may be used by the monitoring WTRU when setting the value of the UTC-based counter to ensure both WTRUs use the same value as the announcing WTRU.

[0080] For example, techniques may use multiple key sets, a first key may be associated with RSC and other key sets may each be associated with a ProSe restricted code. The security material associated with RSC may be used to protect the discovery message. In addition, the security material associated with a ProSe restricted code may be used to protect its corresponding direct discovery sets (e.g., user information ID of end WTRLI) inside the announcement message. Both the relay and end WTRU may be provisioned with the security material associated with the RSC to properly exchange and process the security of the Relay discovery message. The authorized end WTRUs (e.g., only the authorized end WTRUs) may be provisioned with the security material associated with a given ProSe restricted code.

[0081] An example process 400 of relay discovery message protection using the second approach may be illustrated in FIG. 4. The relay discovery message may be a WTRU- to-WTRU relay discovery message 402 (e.g., announcement). The WTRU-to-WTRU relay discovery message 402 may include a message type 404, a UTC-based counter least significant bits (LSB) 406, a message integrity code (MIC) 408, a WTRU-to-WTRU relay information 410, and/or direct discovery sets 420 and 422. The direct discovery set 420 may include a message type 412, a UTC based counter 414, a MIC 416, and/or an end WTRU 418 information. The direct discovery set 422 may include a message type 424, a UTC based counter 426, a MIC 428, and/or an end WTRU 430 information. Compared to the first approach above, each direct discovery set 420 or 422 may be protected using its specific key set associated with the ProSe restricted code.

[0082] In examples, the WTRU authorized to use an RSC may decrypt, alter, and/or replay any direct discovery set transmitted with that RSC. For example, a first WTRU authorized to use a first ProSe service may be able to eavesdrop the content of a relay discovery message including information of a second WTRU using a different ProSe service. Mitigation of this security issue may be possible by enforcing security isolation between ProSe Services (e.g., avoiding multiple ProSe services sharing common RSC keys). However, this may require the configuration of a dedicated RSC for a given ProSe service. This may be defined and set as part of the service deployment.

[0083] In examples, the relay may not be able to protect the direct discovery set using ProSe service specific security material, as the latter is only provisioned at the end WTRU(s) authorized to use the ProSe service. An end WTRU already connected to the relay, may not (need to) transmit discovery messages with protected direct discovery sets to the relay (e.g., relay is discovered to save battery life). In general, for the end WTRU previously discovered, the relay may not replay the direct discovery set of the end WTRU at an arbitrary later time as it may be invalidated at the monitoring end WTRU, because of the UTC-time based replay protection. In this case, the relay may not have access to freshly generated protected direct discovery sets. Therefore, the relay may not be able to properly announce the presence of the end WTRU that is already connected or previously discovered.

[0084] Different approaches may be used under different scenarios. For example, respectively per RSC discovery security and additional per ProSe service discovery security may be used under different scenarios. The first approach may provide simpler deployment options and less impact to existing discovery and/or provisioning procedures. As such, it may be adequate when a dedicated RSC is appropriate or no per ProSe service additional protection is necessary (e.g., used with public safety related ProSe services). The second approach may provide more flexibility in terms of RSC and/or ProSe services deployment and configurations options and provide means to mitigate the above potential security and/or privacy risk. This approach may be well adapted, for example for an RSC used by multiple commercial ProSe services. Coexistence of these techniques may be used to support different deployments scenario and/or varying security requirements.

[0085] One or more techniques associated with model A WTRU-to-WTRU relay discovery using multiple key sets may be disclosed herein. For example, techniques to enable the relay to announce discovered end WTRUs (e.g., while preserving the freshness of the protected direct discovery set received from the discovered end WTRUs) may be disclosed herein.

[0086] A discovery procedure using model A may include the WTRU-WTRU relay using configuration information associated with the RSC to determine whether the RSC supports announcement scheduling assistance. The relay may provide announcement timing information in relay discovery announcement messages. The announcement timing information may include a time window, and offset, a period for future announcements, and the like. The announcing end WTRUs (respectively monitoring end WTRUs) in proximity to the relay may use the announcement timing information to schedule their own relay discovery message transmissions (respectively monitoring). The announcement messages may include protected direct discovery sets. The relay may verify that the discovery message from the announcing end WTRU complies with the timing of the relay discovery announcement message to be sent, for example, before including the end WTRU’s protected direct discovery set in the relay discovery announcement message.

[0087] The techniques described herein may enable the timely delivery of a protected direct discovery set from the announcing end WTRU in the relay announcement messages and/or may ensure that the protected direct discovery set is fresh, for example, when received by the monitoring end WTRU.

[0088] The techniques described herein may also, or alternatively, increase the efficiency associated with the relay discovery process on the announcing end WTRU (e.g., respectively monitoring end WTRU), for example, by allowing the end WTRU to find cycles (e.g., the optimal cycle) and/or or timing opportunities to transmit (respectively monitoring) discovery announcement messages (e.g., to preserve battery life). The end WTRU may select an optimal timing for announcing and/or monitoring, for example, based on announcement timing opportunities advertised by one or more relays in proximity to the end WTRU.

[0089] A WTRU-to-WTRU relay direct discovery model A announcement timing advertisement by relay for end WTRUs is described herein. FIG. 5 illustrates an example ProSe WTRU-to-WTRU relay Model A discovery 500. The example ProSe WTRU-to-WTRU relay Model A discovery 500 may include a relay 502, and one or more end WTRUs 504 and 506. The relay 502 may be a WTRU-to-WTRU relay. The one or more end WTRUs 504 and 506 may be announcing end WTRUs or monitoring end WTRUs. The relay 502 may advertise the next announcement opportunity for the announcing end WTRUs in proximity to the relay 502 (e.g., such as end WTRU 504) and/or monitoring end WTRUs in proximity to the relay 502 (e.g., such as the end WTRU 506).

[0090] At 508, the relay 502 may decide to advertise announcement timing information (e.g., relay announcement timing information) which is based on an indication that RSC supports announcement scheduling assistance, for example, for enabling per ProSe service protection. For example, the relay 502 may determine that the RSC supports announcement scheduling assistance. For example, the announcement timing information may be defined as a time window of when the relay 502 expects to receive the next announcement of the end WTRU via the relay. In another example, the announcement timing information may be defined as a time reference (e.g., deadline) of when the relay will generate and/or transmit the next announcement message. For example, the announcement timing information may indicate a period for future announcements. The announcement timing information may be expressed as an offset value (e.g., relative to the transmission of current announcement message) and/or based on another time reference (e.g., using UTC time). The announcement timing information may indicate the periodicity of the relay announcements (e.g., a period in seconds or minutes, a period for future announcements, and/or a period).

[0091] At 510, the relay 502 may send one or more first relay discovery announcement messages (e.g., first protected relay discovery announcement messages). The one or more first relay discovery announcement messages may be WTRU-to-WTRU relay discovery announcement messages. The one or more first relay discovery announcement messages may indicate the RSC, a WTRU-to-WTRU relay user information identifier (ID), and/or announcement timing information. The relay 502 may send, at 510, the one or more first relay discovery announcement messages based on the determination that the RSC supports announcement scheduling assistance.

[0092] At 512, end WTRU 504 (e.g., the announcing WTRU) may schedule its next announcement based on the received announcement timing information that is advertised by the relay 502. For example, the end WTRU 504 may ensure timely transmission of the announcement such that the announcement arrives within the time window or before the time deadline. If, for example, the end WTRU 504 is in proximity of several candidate relays advertising, the end WTRU 504 may determine and schedule its next announcement based on the received timing information from these relays. End WTRU 504 may determine the preferred timing amongst the relay’s announcement timing information based on one or more of factors. The factors may include the ProSe communication 5 (PC5) signal strength of the relay messages received, the timing of relay announcements (e.g., compared to end WTRU announcements), and/or the frequency of announcements. For example, the end WTRU 504 may align its announcement message to match the announcement of the relay(s) with the best signal strength. In another example, the end WTRU 504 may schedule its next announcement to align with the earliest advertised relay announcement time. In yet another example, the end WTRU 504 may select a relay(s) announcement that is compatible (e.g., in pattern, frequency, periodicity, etc.) with its own announcements e.g., longer period of announcements to preserve battery usage, shorter period of announcements to speed up discovery). End WTRU 506 (e.g., the monitoring WTRU) may align its listening for relay announcement messages based on the received advertised relay announcement timing information.

[0093] At 514, the end WTRU 504 may send a relay discovery message (e.g., a protected relay discovery message) to the relay 502. For example, the relay 502 may receive, at 514, the relay discovery message from the end WTRU 504. The relay discovery message may be a WTRU-to-WTRU relay discovery message. The relay discovery message may indicate the RSC and/or a direct discovery set (e.g., a protected direct discovery set) as described herein.

[0094] At 516, the relay 502 may verify that the announcement message from end WTRU 504 is received within the acceptable time (e.g., based on advertised relay announcement timing information). For example, the relay 502 may determine, at 516, that the received relay discovery message from the end WTRU 504 is compliant with the announcement timing information. The relay discovery message may be determined to be compliant with the announcement timing information when the relay discovery message is received within one or more of the time window, the offset, and/or the period for future announcements. The relay 502 may discard the announcement message from end WTRU 504 if, for example, the announcement message does not comply with advertised relay announcement timing information. The received relay discovery message may not comply with the announcement timing information when the relay discovery message is received at a time that is outside the time window, outside the offset, and/or outside the period for future announcements.

[0095] At 518, the relay 502 may send a second relay discovery announcement message (e.g., a second protected relay discovery announcement message, such as a WTRU-to-WTRU relay discovery announcement message) to the end WTRU 504 and/or the end WTRU 506. For example, the relay 502 may send the second relay discovery announcement message to the end WTRU 504 based on determining, at 516, that the received relay discovery message from the end WTRU 504 is compliant with the announcement timing information. The second relay discovery announcement message may indicate the RSC, the WTRU-to-WTRU relay user information ID, and/or the direct discovery set received from end WTRU 504 (e.g., according to advertised announcement timing information). End WTRU 506 (e.g., the monitoring WTRU) may receive the relay announcement message at a time that aligns with relay announcement timing information and discover end WTRU 504 presence, for example, following the successful processing of the included direct discovery set of end WTRU 504.

Claims

CLAIMS What is claimed is:

1 . A method implemented by a first wireless transmit/receive unit (WTRU), the method comprising: determining that a relay service code (RSC) supports announcement scheduling assistance; sending a first relay discovery announcement message to one or more second WTRUs based on the determination that the RSC supports announcement scheduling assistance, wherein the first relay discovery announcement message indicates the RSC and announcement timing information; receiving a relay discovery message from a second WTRU of the one or more second WTRUs, the relay discovery message indicating the RSC and a direct discovery set of the second WTRU; determining that the received relay discovery message from the second WTRU is compliant with the announcement timing information; and sending a second relay discovery announcement message to the one or more second WTRUs based on the determination that the received relay discovery message is compliant with the announcement timing information, the second relay discovery announcement message indicating the direct discovery set of the second WTRU.

2. The method of claim 1 , wherein the first relay discovery announcement message and the second relay discovery announcement message are WTRU-to-WTRU relay discovery announcement messages.

3. The method of claim 1 or 2, wherein the first relay discovery announcement message indicates a relay user information ID.

4. The method of any of claims 1 to 3, wherein each of the one or more second WTRUs are an announcing end WTRU or a monitoring end WTRU.

5. The method of any of claims 1 to 4, wherein the received relay discovery message is a protected relay discovery message, and the direct discovery set is a protected direct discovery set.

6. The method of any of claims 1 to 5, wherein the announcement timing information comprises one or more of a time window, an offset, a period for future announcements, or a periodicity of announcements.

7. The method of claim 6, wherein the relay discovery message is determined to be compliant with the announcement timing information when the relay discovery message is received within one or more of the time window, the offset, or the period for future announcements.

8. The method of claim 6, further comprising: discarding the received relay discovery message from the second WTRU on condition that the received relay discovery message does not comply with the announcement timing information.

9. The method of claim 8, wherein the received relay discovery message does not comply with the announcement timing information when the received relay discovery message is received at a time that is outside the time window, outside the offset, or outside the period for future announcements.

10. The method of any of claims 1 to 9, wherein the second relay discovery announcement message further comprises respective RSCs and respective direct discovery sets of the one or more second WTRUs.

11. A first wireless transmit/receive unit (WTRU) comprising a processor configured to: determine that a relay service code (RSC) supports announcement scheduling assistance; send a first relay discovery announcement message to one or more second WTRUs based on the determination that the RSC supports announcement scheduling assistance, wherein the first relay discovery announcement message indicates the RSC and announcement timing information; receive a relay discovery message from a second WTRU of the one or more second WTRUs, the relay discovery message indicating the RSC and a direct discovery set of the second WTRU; determine that the received relay discovery message from the second WTRU is compliant with the announcement timing information; and send a second relay discovery announcement message to the one or more second WTRUs based on the determination that the received relay discovery message is compliant with the announcement timing information, the second relay discovery announcement message indicating the direct discovery set of the second WTRU.

12. The first WTRU of claim 11 , wherein the first relay discovery announcement message and the second relay discovery announcement message are WTRU-to-WTRU relay discovery announcement messages.

13. The first WTRU of claim 11 or 12, wherein the first relay discovery announcement message indicates a relay user information ID.

14. The first WTRU of any of claims 11 to 13, wherein each of the one or more second WTRUs are an announcing end WTRU or a monitoring end WTRU.

15. The first WTRU of any of claims 11 to 14, wherein the received relay discovery message is a protected relay discovery message, and the direct discovery set is a protected direct discovery set.

16. The first WTRU of any of claims 11 to 15, wherein the announcement timing information comprises one or more of a time window, an offset, a period for future announcements, or a periodicity of announcements.

17. The first WTRU of claim 16, wherein the relay discovery message is determined to be compliant with the announcement timing information when the relay discovery message is received within one or more of the time window, the offset, or the period for future announcements.

18. The first WTRU of claim 16, wherein the processor is further configured to discard the received relay discovery message from the second WTRU on condition that the received relay discovery message does not comply with the announcement timing information.

19. The first WTRU of claim 18, wherein the received relay discovery message does not comply with the announcement timing information when the received relay discovery message is received at a time that is outside the time window, outside the offset, or outside the period for future announcements.

20. The first WTRU of any of claims 11 to 19, wherein the second relay discovery announcement message further comprises respective RSCs and respective direct discovery sets of the one or more second WTRUs.