Method for coordinated privacy protection using initial connection release during relay reselection

Abstract

In systems, methods, and / or devices, there may be methods for wireless transmit-receive unit (WTRU) to WTRU connections, utilizing more than one connections, selecting connections, ensuring security and privacy, and using one or more relays.

Description

[0001] This divisional application is a divisional application with a filing date of April 4, 2024, an application number of 202480002548.1, and an invention name of "Method for coordinated privacy protection using initial connection release during relay reselection".

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application No. 63 / 457,073, filed on April 4, 2023, the contents of which are incorporated herein by reference. Background Art

[0004] In a wireless communication system, there is a need to solve the problem of how a first device and a second device can securely transmit information via a third device acting as a relay. Summary of the invention

[0005] In a system, method, and / or apparatus, there may be a method for a wireless transmit receive unit (WTRU) to WTRU connection, utilizing more than one connection, selecting a connection, ensuring security and privacy, and using one or more relays. A WTRU may implement a method for privacy protection using link modification operations during relay reselection. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements, and in which:

[0007] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0008] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0009] Figure 1C is an example of an embodiment in which Figure 1A a system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0010] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0011] Figure 2 An example of 5G ProSe layer 2 UE-to-UE relay reselection is illustrated;

[0012] Figure 3 An example of 5G ProSe UE-to-UE relay reselection with a new KNRP ID established using LMR / LMA is illustrated;

[0013] Figure 4 An example of 5G ProSe UE-to-UE relay reselection with new KNRP ID using LMR / LMA / LMAck is illustrated;

[0014] Figure 5 An example of 5G ProSe UE-to-UE relay reselection with coordinated initial connection release for new KNRP ID establishment is illustrated;

[0015] Figure 6 An example of 5G ProSe UE-to-UE relay reselection with KNRP ID state set to “pending refresh” is illustrated;

[0016] Figure 7 An example of 5G ProSe UE-to-UE relay reselection security using enhanced pre-keying procedures is illustrated; and

[0017] Figure 8 An example of a method is illustrated. DETAILED DESCRIPTION

[0018] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 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 discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0019] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood 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 (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the UEs 102a, 102b, 102c, and 102d may be interchangeably referred to as a WTRU.

[0020] The communication system 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, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, 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 should 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, 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), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send 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 a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver 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 send and / or receive signals in a desired spatial direction.

[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 communication 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, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. 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 ​​Uplink (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) that 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 that may establish the air interface 116 using 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 together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0027] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, 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), etc.

[0028] Figure 1AThe base station 114b in the example may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, 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 a femtocell. As Figure 1A As shown, the base station 114 b may have a direct connection to the Internet 110. Therefore, the base station 114 b may not need to access the Internet 110 via the CN 106.

[0029] The RAN 104 may be in communication with the CN 106, 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 different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the accompanying drawings, the CN 106 may be 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. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0030] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides 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), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication 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 or a different RAT.

[0031] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication 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 via different wireless links). Figure 1A The illustrated WTRU 102c 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] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, 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. It will be appreciated that the WTRU 102 may include any sub-combination 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 associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, 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. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0034] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0035] Although the transmit / receive element 122 Figure 1B 102 as a single element, but 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 signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0037] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit) and may receive user input data therefrom. 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 a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only 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 a 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 power to 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, etc.

[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 from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0040] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules 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 electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulation (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, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geographic location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[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 specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0042] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with 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 evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-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 evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-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 evolved Node 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 UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0045] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While the foregoing elements are depicted as part of the CN 106, it should be understood 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 evolved Node-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, etc. 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 evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an 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 the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context 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 be in communication with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0050] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments such terminals may (eg, temporarily or permanently) employ a wired communications interface with a communications network.

[0051] In a representative embodiment, 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 access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and directed to the STA may arrive through the AP and may be delivered to the STA. Traffic originating from the STA and directed to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted through the AP, for example, where the source STA may transmit traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the destination STA (e.g., directly between them) using direct link establishment (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0053] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send a beacon on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a specific STA, the specific 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 communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0055] Very High Throughput (VHT) STAs may support 20MHz, 40MHz, 80MHz, and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels may be formed by combining consecutive 20MHz channels. A 160MHz channel may be formed by combining 8 consecutive 20MHz channels, or by combining two non-contiguous 80MHz channels (this may be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data may pass through a segment parser that may divide the data into two streams. Each stream may be individually processed by an inverse fast Fourier transform (IFFT) and time domain processing. These streams may be mapped to two 80MHz channels, and data may be sent by a transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed, and the combined data may be transmitted to the medium access control (MAC).

[0056] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0057] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum 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 (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports a 1MHz operating mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0058] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0059] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR 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.

[0060] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 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, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send 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 an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and the gNB 180b (and / or the gNB 180c).

[0061] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, 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 the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths over 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 a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0063] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. As shown in FIG. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0064] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood 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 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 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 MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 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 the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0067] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the 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 DL packets, providing mobility anchoring, etc.

[0068] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0069] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0070] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions 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. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0071] One or more simulation devices may perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device may be used in a test lab and / or a test scenario in a non-deployed (e.g., testing) wired and / or wireless communication network to enable testing of one or more components. One or more simulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by the simulation device to send and / or receive data.

[0072] As described in this document, the following acronyms may be used: Break Before Make (BBM); Break Before Make (MBB); Direct Connection Request / Accept (DCR / DCA); (Root) Key NR ProSe (KNRP); Session Key NR ProSe (KNRP-Sess); Link Modification Request / Accept (LMR / LMA); Least / Most Significant Byte (LSB / MSB); NR ProSe Encryption Key (NRPEK); NR ProSe Integrity Key (NRPIK); Relay Service Code (RSC); and / or UE-to-UE Relay (U2U Relay).

[0073] In general, a relay may be any device, such as a WTRU, a UE, a base station, a virtualized device residing on another hardware, etc.; further, as described herein, reference to a "terminal" WTRU may indicate that the WTRU is at one end (e.g., the first end or the second end in a simple relay scenario) of a communication link enabled by at least one relay device (e.g., a relay WTRU). An L2U2U relay reselection / selection procedure may include two terminal WTRUs communicating via a first relay, which subsequently negotiate a selection of a second relay on the first relay before reconnecting via the second relay (e.g., during a link modification procedure). The terminal WTRU may determine to trigger relay reselection, for example, to find a better relay (e.g., one that provides better signal quality / performance).

[0074] Figure 2An example 5G ProSe Layer 2 (L2) UE to UE (U2U) (e.g., WTRU to WTRU) relay reselection is illustrated.

[0075] from Figure 2 As can be seen in the example of , in the reselection procedure, multiple devices may be involved, such as terminal WTRU1 251 (e.g., having 5G ProSe functionality or other functionality), relay 1 252, relay 2 253, and / or terminal WTRU2 254 (e.g., having 5G ProSe functionality or other functionality). Initially at 201, a connection may be established between terminal WTRU1 and terminal WTRU2 via relay 1. At 202, the terminal WTRUs may communicate (e.g., traffic transfer, etc.) via relay 1. At least one of the terminal WTRUs (e.g., terminal WTRU1) may determine to reselect a relay (e.g., at 203). The terminal WTRU may then negotiate the selection of another relay (e.g., relay 2) via relay 1. For example, at 204, terminal WTRU1 may transmit a link modification request message to a second terminal WTRU via relay 1. At 205, terminal WTRU2 may be instructed, assisted, and / or determine the relay WTRU (e.g., relay 2) to which to switch. At 206, terminal WTRU2 may transmit a link modification accept message to terminal WTRU2 via Relay 1. This link modification procedure (eg, 204-206) may be performed before reconnecting the two terminal WTRUs via a new relay (eg, Relay 2) at 207.

[0076] In some cases, there may be one or more security methods related to / associated with the L2 U2U relay reselection / selection procedure. In this case, there may be one or more security methods that are part of the link modification procedure (e.g., Figure 2 The new key may be used to protect the connection between the terminal WTRU via the second relay.

[0077] The Key NR ProSe (KNRP) ID is a unique identifier of the root key KNRP shared between two WTRUs participating in direct communication. The KNRP and its accompanying KNRP ID value are not deleted after the unicast link is released. In order to prevent the privacy threat of an eavesdropper using the same KNRP ID between two WTRUs participating in direct communication to link two subsequent connections, the KNRP ID may be changed during the link release procedure. The change of the KNRP ID may be performed unconditionally between the two WTRUs as part of the link release procedure before the terminating WTRU reconnects again.

[0078] The key update procedure can be used for an ongoing connection to ensure that new session key KNRP-SESS and security keys NR ProSe encryption key (NRPEK) and NR ProSe integrity key (NRPIK) are used. The procedure can also be optionally used to refresh KNRP.

[0079] The connection between the terminating WTRUs via the original L2 U2U relay may not be released before a new connection is established via the new L2 U2U relay. This stems from the fact that the release of the initial link reselected with the original relay depends on whether the PC5 unicast link is still needed and the WTRU specific implementation, and due to the make-before-break (MBB) principle on which the relay reselection procedure is based. The MBB principle stipulates that the current connection between the terminating WTRUs via the original L2 U2U relay should be maintained to allow a seamless transition to communicate over the new connection via the new L2 U2U relay.

[0080] In general, it may be assumed that the terminal WTRU maintains the initial connection achieved via the first U2U relay while establishing a new connection via the second U2U relay in MBB mode. This may be required to minimize any potential disruption to ongoing communications during the U2U reselection procedure. Maintaining the initial connection means that the mechanism described herein using link release cannot be applied in MBB scenarios.

[0081] In the event that the terminating WTRU (e.g., due to resource constraints) needs to release the initial connection early, the terminating WTRU may not perform a link release procedure for the original connection implemented via the first L2 U2U relay before reconnecting via the new L2 U2U relay, and / or the terminating WTRU may reuse the same KNRP ID over the new E2E connection. Therefore, there is a need to address the issue of how to ensure correct timing of link release for the initial connection before initiation of unspecified new connection establishment in potential break-before-make (BBM) scenarios.

[0082] In both cases (eg, MBB scenario and BBM scenario), an eavesdropper may be able to track the terminating WTRU reusing the same KNRPID. Therefore, there is a need to address issues that may arise as described herein, such as how to ensure KNRP ID privacy protection during L2 U2U reselection.

[0083] As described herein, preparing new security keys using a connection implemented via a first relay during a link modification procedure provides the benefit of early security establishment for faster link establishment implemented via the new relay, and also provides the availability of security keys protecting initial messages (e.g., direct connection requests (DCRs)).

[0084] However, it may be desirable to improve existing security procedures in link modification procedures and / or reduce security-related logic to reduce the impact on existing implementations.

[0085] The establishment of new keys may also depend on the provided security policy, which needs to be taken into account for the preparation of the new security keys. Therefore, it is necessary to solve the problem of how to establish new security keys during the relay reselection procedure (e.g., for a new connection achieved via a second relay), while taking into account the provided security policy and the potential impact on the existing procedures (e.g., minimizing).

[0086] In one or more examples described herein (e.g., for KNRP ID privacy), there may be an L2 U2U reselection procedure in which a first terminal WTRU (terminal WTRU1) establishes a new KNRP ID with a second terminal WTRU (terminal WTRU2) using a link modification procedure or coordinated link release of an initial connection implemented via a first relay (relay 1). Terminal WTRU1 establishes a new connection with terminal WTRU2 via a second relay (relay 2) using the new KNRP ID. This method enables privacy protection of the KNRP ID when the terminal WTRU establishes a new connection via relay 2 (e.g., mitigating the risk of an attacker linking the new KNRP ID with the old KNRP ID); in other words, this achieves privacy of the new key ID and ensures that it is protected during the link procedure (e.g., as described herein). The method described herein proposes to utilize and enhance the link modification procedure, which is mandatory for L2 U2U reselection, to negotiate the maintenance (MBB) or release (BBM) of the initial connection before establishing a new connection. If MBB is selected, the terminating WTRU establishes a new KNRP ID as part of the link modification procedure. If BBM is selected, the terminating WTRU coordinates the link release procedure for the initial connection to establish a new KNRP ID before initiating a new connection establishment. In this way, the problem that an attacker may try to link the old key ID with the new key ID to track the WTRU can be avoided.

[0087] In one or more examples described herein (e.g., for communication security), there may be a L2 U2U reselection security procedure in which a first terminal WTRU (terminal WTRU1) negotiates with a second WTRU (terminal WTRU2) via a first relay (relay 1) using a link modification procedure, and / or performs an enhanced key update procedure. Terminal WTRU1 performs an enhanced key update procedure with terminal WTRU2 to establish a new correlation ID and generate new keys for protecting a new connection via a second relay (relay 2). This method enables the preparation of security keys to protect new connection establishment, including initial messages (e.g., DCR), while improving the key update procedure.

[0088] Figure 3 An example of 5G ProSe U2U relay reselection with privacy protection of KNRP ID is illustrated. As shown, multiple devices may be involved in the reselection procedure, such as terminal WTRU1 351, relay 1 352, relay 2 353 and / or terminal WTRU2 354. Figure 3 A series of ordered acts / events is presented, but it is contemplated that one or more of these acts / events may be optional and / or one or more of these acts / events may occur / be performed in an order different from that presented.

[0089] At 301, a connection for unicast communication may be established between terminal WTRUs via Relay 1. Terminal WTRU 2 may transmit a protected direct security mode (DSM) command including security parameters (e.g., session key identifier, random number, part of security algorithm / policy) to terminal WTRU 2. In response, terminal WTRU 1 may transmit a protected direct security mode (DSM) complete including security parameters (e.g., session key identifier, security policy, and other parts) to terminal WTRU 2.

[0090] At 302, there may be one or more messages (eg, data traffic, etc.) transmitted / received between terminal WTRUs via Relay 1.

[0091] At 303, terminal WTRU1 may decide to perform U2U relay reselection with terminal WTRU2 based on one or more conditions described herein, such as resource usage conditions, configuration restrictions on simultaneous connections for the same service, and / or other conditions described herein. Terminal WTRU1 determines to generate a new KNRP ID with terminal WTRU2 based on a decision to maintain the current connection implemented via relay 1. For example, terminal WTRU1 may determine to maintain the initial connection based on the availability of resources for the new connection. In another example, terminal WTRU1 may determine to maintain the initial connection based on a configuration parameter that controls the use of simultaneous connections (e.g., the maximum number of simultaneous connections allowed by a ProSe service or RSC). In other words, regarding the decision to maintain the connection, after deciding to perform reselection and assuming that the current connection is maintained, terminal WTRU1 may decide to generate a new key ID.

[0092] At 304, terminal WTRU1 may transmit a link modification request (LMR) message to terminal WTRU2, which may include an indication to maintain the initial connection before establishing a connection via relay 2, a newly allocated MSB of the KNRP ID, and / or other parameters (e.g., a reselection indication, an identifier of a relay candidate including relay 2). The newly allocated MSB of the KNRPID associated with terminal WTRU2 uniquely identifies the KNRP in terminal WTRU1. Terminal WTRU1 may include parameters for whether / when to release the initial connection after the new connection is established (e.g., release timer, maintain connection, release data communication on the new connection). In other words, the newly allocated MSB is used to create a new KNRP ID for the current key; upon receiving the LSB from terminal WTRU2 later in the process, terminal WTRU1 may create a new KNRP ID (e.g., for the current key) by combining the MSB and the LSB, as further described herein.

[0093] At 305, terminal WTRU2 may select relay 2 from the list of relay candidates. Terminal WTRU2 may assign the LSB of the KNRP ID associated with terminal WTRU1, which uniquely identifies the KNRP in terminal WTRU2. Terminal WTRU2 may then combine the MSB of the KNRP ID received from terminal WTRU1 and the LSB of the KNRP ID to form a new KNRP ID to be used when reconnecting with terminal WTRU1. Terminal WTRU2 replaces the old KNRP ID with the new KNRP ID. Terminal WTRU2 may transmit a link modification accept (LMA) message to terminal WTRU1, which includes the LSB of the KNRP ID and / or other parameters (e.g., an identifier of the selected relay 2). If the LMR does not include any release / maintain indication, the maintenance of the initial connection may be assumed by default by the terminal WTRU or left to the terminal WTRU to select (e.g., see Figure 4 The terminal WTRU2 may allocate the LSB of the KNRP ID based on the initial connection maintenance indication and / or the received MSB of the KNRP ID.

[0094] At 306, terminal WTRU1 may combine the MSB of the KNRP ID transmitted at 304 with the LSB of the KNRP ID received from terminal WTRU2 to form a new KNRP ID to be used when reconnecting with terminal WTRU2. Terminal WTRU1 may replace the old KNRP ID with the new KNRP ID. Terminal WTRU1 may transmit a DCR message including the new KNRP ID to terminal WTRU2 via relay 2 (e.g., a direct PC5 link with relay 2 may have been previously established or modified).

[0095] At 307, terminal WTRU1 and terminal WTRU2 may establish security for the connection between the terminal WTRUs via Relay 2. The KNRP ID is used to locate the corresponding KNRP for deriving session and security keys to protect the connection. In other words, the KNRP does not change, but the KNRP ID does (e.g., so new MSBs and LSBs are required).

[0096] At 308, terminal WTRU1 may receive a DCA from terminal WTRU2 that completes the connection establishment. The terminal WTRU (eg, terminal WTRU1 or terminal WTRU2) determines whether to continue to maintain the initial connection or release the initial connection via Relay 1 based on the above parameters (eg, timer, data packets exchanged on the new connection).

[0097] Figure 4 An example of a 5G ProSe U2U relay reselection with KNRP ID privacy protection based on negotiation of initial PC5 connection release or maintenance before establishing a PC5 connection via a selected relay is illustrated. As shown, multiple devices may be involved in the reselection procedure, such as terminal WTRU1 451, relay 1 452, relay 2 453, and / or terminal WTRU2 454. Although Figure 4 A series of ordered acts / events is presented, but it is contemplated that one or more of these acts / events may be optional and / or one or more of these acts / events may occur / be performed in an order different from that presented.

[0098] At 401 , a connection is established between terminal WTRUs via Relay 1 for unicast communication.

[0099] At 402, there may be one or more messages (eg, data traffic, etc.) transmitted / received between terminal WTRUs via Relay 1.

[0100] At 403, terminal WTRU1 determines to perform U2U relay reselection with terminal WTRU2.

[0101] At 404, terminal WTRU1 transmits a link modification request (LMR) message to terminal WTRU2, which may include a release indication or a maintain (e.g., preference) indication and / or other parameters (e.g., a reselect indication, an identifier of a relay candidate including relay 2). In some cases, the release indication is used to request the release of the initial PC5 connection before establishing a connection via the selected relay. In some cases, the maintain indication is used to request the maintenance of the initial PC5 connection during the establishment of the connection via the selected relay.

[0102] At 405, terminal WTRU2 selects Relay 2 from the relay candidate list. Terminal WTRU2 determines to maintain the initial connection (e.g., based on terminal WTRU1 maintenance preference, ProSe / RSC service configuration and / or terminal WTRU2 resource usage) and allocates a new LSB of the KNRP ID associated with terminal WTRU1. Terminal WTRU2 transmits a Link Modification Accept (LMA) message to terminal WTRU1, the LMA message including the maintenance indication and the LSB of the KNRP ID and other parameters (e.g., the identifier of the selected Relay 2). Once the new connection is established as described herein, terminal WTRU2 may include parameters on how to handle the maintained initial connection (e.g., timer-based release, etc.).

[0103] At 406, terminal WTRU1 accepts maintenance of the initial PC5 connection. Terminal WTRU1 allocates a new MSB of the KNRP ID and combines the new MSB and the new LSB of the KNRP ID to form a new KNRP ID to be used when reconnecting with terminal WTRU2. Terminal WTRU1 replaces the old KNRP ID with the new KNRP ID. Terminal WTRU1 transmits a Link Modification Confirm message to terminal WTRU2, which includes the MSB of the KNRP ID. Terminal WTRU2 combines the new MSB and the new LSB of the KNRP ID to form a new KNRP ID (e.g., the same as the KNRPID formed by terminal WTRU1), which is used when reconnecting with terminal WTRU1. Terminal WTRU2 replaces the old KNRP ID with the new KNRP ID.

[0104] At 407, terminal WTRU1 transmits a DCR message including the new KNRP ID to terminal WTRU2 via relay 2.

[0105] At 408, terminating WTRU1 and terminating WTRU2 establish security for the connection between terminating WTRUs via Relay 2. The new KNRP ID is used to locate the corresponding KRNP for deriving session and security keys to protect the connection.

[0106] At 409, terminal WTRU1 receives a DCA from terminal WTRU2 completing the connection establishment. The initial connection is maintained or released based on one or more parameters discussed herein (eg, 405 or elsewhere).

[0107] Figure 5 An example of 5G ProSe U2U relay reselection with privacy protection of KNRP ID is illustrated. As shown, multiple devices may be involved in the reselection procedure, such as terminal WTRU1 551, relay 1 552, relay 2 553 and / or terminal WTRU2 554. Figure 5 A series of ordered acts / events is presented, but it is contemplated that one or more of these acts / events may be optional and / or one or more of these acts / events may occur / be performed in an order different from that presented.

[0108] At 501 , a connection is established between terminal WTRUs via Relay 1 for unicast communication.

[0109] At 502, there may be one or more messages (eg, data traffic, etc.) transmitted / received between terminal WTRUs via Relay 1.

[0110] At 503, terminal WTRU1 determines to perform U2U relay reselection with terminal WTRU2 and coordinates to release the initial connection (e.g., before the new connection is established). For example, terminal WTRU1 may determine to release resources exhausted by the initial connection. In another example, WTRU1 may determine to release the initial connection based on a configuration parameter controlling the use of simultaneous connections (e.g., the maximum number of simultaneous connections allowed by a ProSe service or RSC).

[0111] At 504, terminal WTRU1 transmits a link modification request (LMR) message to terminal WTRU2, the LMR message including an indication requesting a coordinated release of the initial connection via Relay 1 and / or other parameters (e.g., a reselect indication, identifiers of relay candidates including Relay 2). Based on the release indication, terminal WTRU2 stops using the initial connection to send data packets and other link maintenance messages (e.g., Keep Alive, Link Identifier Update), and starts a timer for expected receipt of a link release request from terminal WTRU1.

[0112] At 505, terminal WTRU2 transmits a Link Modification Accept (LMA) message to terminal WTRU1, which includes acceptance of the coordinated release of the initial connection via Relay 1 and other parameters (e.g., the identifier of the selected Relay 2). Terminal WTRU1 stops sending data packets and / or other link maintenance messages (e.g., keep alive, link identifier update) as appropriate. If terminal WTRU2 is expected to initiate a link release, terminal WTRU1 starts a timer for expected receipt of a link release request from terminal WTRU2.

[0113] At 506, terminal WTRU1 transmits a link release request message including the new MSB of the KNRP ID to terminal WTRU2. Alternatively, after the LMA, terminal WTRU2 may transmit the link release request message instead of terminal WTRU1.

[0114] At 507, terminal WTRU2 transmits a link release response message including the LSB of the KNRP ID to terminal WTRU1. Terminal WTRU2 combines the received MSB and the LSB of the KNRP ID to establish a new KNRP ID.

[0115] Figure 6 An example of 5G ProSe U2U relay reselection with privacy protection of KNRP ID based on a new state associated with the KNRP ID is illustrated. As shown, multiple devices may be involved in the reselection procedure, such as terminal WTRU1 651, relay 1 652, relay 2 653, and / or terminal WTRU2 654. Although Figure 6 A series of ordered acts / events is presented, but it is contemplated that one or more of these acts / events may be optional and / or one or more of these acts / events may occur / be performed in an order different from that presented.

[0116] At 601 , a connection is established between terminal WTRUs via Relay 1 for unicast communication.

[0117] At 602, there may be one or more messages (eg, data traffic, etc.) transmitted / received between terminal WTRUs via Relay 1.

[0118] At 603, terminal WTRU1 determines to perform U2U relay reselection with terminal WTRU2.

[0119] At 604, terminal WTRU1 transmits a link modification request (LMR) message to terminal WTRU2, which may include a release indication or a maintain (e.g., preference) indication and / or other parameters (e.g., a reselect indication, an identifier of a relay candidate including relay 2). In some cases, the release indication is used to request the release of the initial PC5 connection before establishing a connection via the selected relay. In some cases, the maintain indication is used to request the maintenance of the initial PC5 connection during / after establishing a connection via the selected relay.

[0120] At 605, terminal WTRU2 selects relay 2 from the relay candidate list. After completing the connection establishment via the selected relay, terminal WTRU2 determines to maintain the initial PC5 connection. Terminal WTRU2 associates a state to the KNRP ID associated with a pair of terminal WTRU1 / terminal WTRU2 and sets it to "pending refresh". In some cases, the "pending refresh" state means that the KNRP ID can no longer be used during a new PC5 link establishment (e.g., with respect to a DCR message) and a new KNRP ID needs to be generated.

[0121] At 606, terminal WTRU2 transmits a Link Modification Accept (LMA) message to terminal WTRU1, which may include a maintain indication and / or other parameters (e.g., an identifier of the selected Relay 2). In some cases, maintain is preferred over release (e.g., break before make); for example, if one of the terminal WTRUs prefers to maintain the PC5 connection and the other terminal WTRU prefers to release the connection, the PC5 connection is maintained. In some cases, maintain is assumed by default (e.g., if no indication is specified on the LMR).

[0122] At 607, terminal WTRU1 sets the KNRP ID state to "pending refresh" based on the received maintenance indication. Since the KNRP ID state is set to "pending refresh", terminal WTRU1 determines to establish a new PC5 connection via Relay 2 without using the existing KNRP ID.

[0123] At 608, terminal WTRU1 transmits a DCR message to terminal WTRU2 via relay 2 and does not include a KNRP ID associated with a pair of terminal WTRU1 / terminal WTRU2, even if KNRP / KNRP ID exists. In general, the DCR message may include other parameters such as target user information, security policy information, etc.

[0124] At 609, terminal WTRU1 and terminal WTRU2 authenticate each other via Relay 2. A new KNRP / KNRP ID is derived. The existing KNRP ID is replaced with the newly derived value and its status is set to "valid", which means that the KNRP / KNRP ID can be used for session key derivation and the KNRP ID can be used for other PC5 connection establishment. Note that Figure 6 Examples of (eg, as illustrated in this step) involve scenarios where a full authentication procedure (eg, new key and new key ID) is required.

[0125] At 610, terminating WTRU1 and terminating WTRU2 establish security for the connection between terminating WTRUs via Relay 2. The KNRP ID is used to locate the corresponding KRNP for deriving session and security keys to protect the connection.

[0126] At 611, terminal WTRU1 receives a DCA from terminal WTRU2 completing the connection establishment.

[0127] Figure 7 An example of 5G ProSe U2U relay reselection security with key pre-setting for a new connection with a second relay is illustrated. As shown, multiple devices may be involved in the reselection procedure, such as terminal WTRU1 751, relay 1 752, relay 2 753, and / or terminal WTRU2 754. Figure 7 A series of ordered acts / events is presented, but it is contemplated that one or more of these acts / events may be optional and / or one or more of these acts / events may occur / be performed in an order different from that presented.

[0128] At 701 , a connection is established between terminal WTRUs via Relay 1 for unicast communication.

[0129] At 702, there may be one or more messages (eg, data traffic, etc.) transmitted / received between terminal WTRUs via Relay 1.

[0130] At 703, terminal WTRU1 determines to perform U2U relay reselection with terminal WTRU2. Terminal WTRU1 determines to perform key provisioning for a new connection via the current connection based on the current connection security policy / configuration (e.g., signaling integrity is turned on). Terminal WTRU1 allocates a new MSB of the correlation ID.

[0131] At 704, terminal WTRU1 transmits a link modification request (LMR) message to terminal WTRU2, the LMR message including the MSB of the correlation ID, a new connection key preset indication, and / or other parameters (eg, a reselection indication, identifiers of relay candidates including Relay2).

[0132] At 705 (e.g., 705a and 705b), terminal WTRU2 allocates the LSB of the correlation ID, combines the MSB and LSB of the correlation ID to form a new correlation ID, and stores the correlation ID along with terminal WTRU1 information (e.g., user information ID, KNRP / KNRP ID) and / or relay 2 information (e.g., user information ID, L2 ID) in a new connection context associated with relay 2. Terminal WTRU2 transmits a link modification accept (LMA) message to terminal WTRU1, the LMA message including confirmation of the new connection, the correlation ID, and / or other parameters (e.g., an identifier of the selected relay 2).

[0133] At 706 (e.g., 706a and 706b), terminal WTRU1 combines the MSB and LSB to form a new correlation ID and stores the new correlation ID in a new connection context associated with relay 2 along with terminal WTRU2 information and / or relay 2 information. Terminal WTRU1 transmits a key provisioning request message or a key update request message including an indication of generating a new key for the new connection to terminal WTRU2 via the first relay. Terminal WTRU1 includes the correlation ID and / or other key update security parameters (e.g., security capabilities, random number, MSB of the new KNRP-SESS ID) in the message.

[0134] At 707 (e.g., 707a and 707b), terminal WTRU2 generates a new session (KNRP-SESS) and security keys (NRPEK and NRPIK) and stores the keys in the new connection context. Terminal WTRU2 transmits a DSM command message including the correlation ID and conventional key update security parameters to terminal WTRU1 via relay 1. The message is protected using the established security context for the current connection (e.g., no indication to lower layers to activate new security using new keys is transmitted).

[0135] At 708, terminal WTRU1 receives a DSM command message including a correlation ID and conventional key update security parameters from terminal WTRU2. Terminal WTRU1 generates new security keys and stores them in the new connection context. Terminal WTRU1 transmits a DSM complete message to terminal WTRU2 via the first relay.

[0136] At 709, terminal WTRU2 transmits a key update response message to terminal WTRU1 confirming that terminal WTRU2 is ready to use the new key in the connection via the second relay.

[0137] At 710, terminal WTRU1 transmits an integrity protected DCR message including a correlation ID to terminal WTRU2 via relay 2. The message is protected using a new key associated with the new connection context. Authentication and security establishment procedures may be skipped on the new connection. Terminal WTRU2 locates the new connection security key based on the correlation ID. Terminal WTRU2 activates the security context for the new connection using the stored new connection security key. Terminal WTRU2 transmits a DCA to the fully protected terminal WTRU1 using the security context. Terminal WTRU1 activates the security context for the new connection using the stored new connection security key located with the correlation ID.

[0138] In one example, there may be a method for (root) key NR ProSe (KNRP) privacy protection using Link Modification Request / Accept / Confirm (LMR / LMA / LMAck) during a L2 U2U relay reselection procedure. This procedure may establish a new KNRP ID during a link modification procedure where the peer WTRU accepts an initial connection maintenance preference. Terminal WTRU1 establishes a new KNRP ID with terminal WTRU2 via a first relay during a U2U relay reselection procedure and uses the new KNRP ID during connection establishment via a second relay.

[0139] Initially in this example, terminal WTRU1 may determine to establish a new KNRP ID for the new connection during reselection based on a decision to maintain the current connection via the first relay (eg, based on ProSe service / RSC configuration, current resource usage).

[0140] Terminal WTRU1 may transmit an LMR message to terminal WTRU2 via the first relay, the LMR message including an indication for maintaining the initial connection before establishing the connection via the second relay, and the MSB of the newly allocated KNRP ID to notify terminal WTRU2 to update the current KNRP ID shared with terminal WTRU1.

[0141] Terminal WTRU1 may receive an LMA message from terminal WTRU2 including a new LSB of the KNRP ID.

[0142] Terminal WTRU1 may combine the new MSB of the KNRP ID and the new LSB of the KNRP ID.

[0143] Terminal WTRU1 may store the new KNRP ID by replacing the current KNRP ID.

[0144] Terminal WTRU1 may transmit a DCR message including a new KNRP ID to terminal WTRU2 via the second relay.

[0145] Terminal WTRU1 may receive a DCA message from terminal WTRU2 via the second relay.

[0146] Terminal WTRU1 may determine to initiate the release of the initial connection or to maintain the initial connection.

[0147] In one example, there may be a method to establish a new KNRP ID during a link modification procedure where a peer WTRU connection release is not accepted by the peer WTRU.

[0148] Initially in this example, terminal WTRU1 determines to establish a new KNRP ID for the new connection during reselection based on a decision to maintain the current connection via the first relay (eg, based on ProSe service / RSC configuration, current resource usage).

[0149] Terminal WTRU1 may transmit an LMR message to terminal WTRU2 via the first relay, the LMR message including an indication that the initial connection is preferably released before establishing a connection via the second relay.

[0150] Terminal WTRU1 may receive an LMA message from terminal WTRU2 including a new LSB of the KNRP ID.

[0151] Terminal WTRU1 may transmit a LMAck including the new MSB of the KNRP ID to terminal WTRU2 via the first relay.

[0152] Terminal WTRU1 combines the new MSB of the KNRP ID with the new LSB of the KNRP ID.

[0153] Terminal WTRU1 uses the new KNRP ID during establishment of a new connection via the second relay.

[0154] In one example (as further described herein), there may be a method for KNRP ID privacy protection using coordination of initial connection release during L2 U2U relay reselection procedures. A new KNRP ID may be established by coordinating the link release of the initial connection achieved via the first relay using a link modification procedure.

[0155] Initially in this example, terminal WTRU1 may coordinate the release of a current connection with terminal WTRU2 via a first relay to establish a new KNRP ID, which may then be used when establishing a new connection via a second relay.

[0156] Terminal WTRU1 may determine to coordinate the release of the current connection and establish a new KNRP ID for the new connection (eg, based on ProSe service / RSC configuration, current resource usage).

[0157] Terminal WTRU1 may transmit an LMR message to terminal WTRU2 via the first relay, the LMR message including an indication to release the initial connection before establishing a new connection via the second relay.

[0158] Terminal WTRU1 may receive an LMA message including confirmation of the release of the initial link from terminal WTRU2. Note that LMR / LMA negotiates the release but does not actually trigger the release.

[0159] Terminal WTRU1 may transmit a link release request including the newly allocated MSB of the KNRP ID to terminal WTRU2 via the first relay. Note that the link release request actually triggers the release of the connection.

[0160] Terminal WTRU1 may receive a link release response including a new LSB of the KNRP ID from terminal WTRU2.

[0161] The terminal WTRU1 may combine the new MSB of the KNRP ID and the new LSB of the KNRP ID and store the new KNRP ID by replacing the current KNRPID

[0162] Terminal WTRU1 transmits a DCR message including a new KNRP ID to terminal WTRU2 via the second relay (upon receiving a Link Release Response message from terminal WTRU2).

[0163] In one example (as further described herein), there may be a method for key provisioning of a new connection procedure during an L2 U2U relay reselection procedure. A new security key may be generated during a relay reselection procedure for an initial connection achieved via a first relay. The new key may be used for security of a new connection achieved via a second relay.

[0164] Initially in this example, during the U2U relay reselection procedure via the first relay, terminal WTRU1 may negotiate key provisioning of security keys to be used to protect the connection via the second relay.

[0165] The terminal WTRU1 may determine to perform an enhanced key update as part of the U2U relay reselection procedure based on the security policy / configuration used for the initial connection via the first relay (eg, a non-null integrity algorithm is in use).

[0166] Terminal WTRU1 may transmit an LMR message to terminal WTRU2 via the first relay, the LMR message including an indication to perform an enhanced key update to generate new session keys before establishing a new connection via the second relay, and the MSB of the newly assigned correlation ID, a relay identifier list.

[0167] Terminal WTRU1 may receive an LMA message from terminal WTRU2, the LMA message including a confirmation for performing enhanced key update, an identifier of the selected second relay, and the LSB of the new correlation ID. Terminal WTRU1 combines the MSB and LSB of the correlation ID to form a correlation ID for associating the initial connection and the new connection (to be established).

[0168] Terminal WTRU1 can transmit a key update request message to terminal WTRU2 via the first relay, wherein the key update request message includes an indication of generating a new key for a new connection, an identifier associated with the second relay (e.g., any one of a user information ID, an L2 ID, and a related ID), and other key update security parameters (e.g., security capabilities, a random number, and the MSB of a new KNRP-SESS ID).

[0169] Terminal WTRU1 may receive a DSM command message from terminal WTRU2 including a correlation ID and conventional key update security parameters.

[0170] The terminal WTRU1 may generate new session keys with identifiers (KNRP-SESS and ID) and new security keys (NRPEK and NRPIK) to be used with the new connection.

[0171] Terminal WTRU1 may store the new key for the new connection along with the existing KNRP ID and an identifier associated with the second relay.

[0172] Terminal WTRU1 may transmit a DSM completion message to terminal WTRU2 via the first relay.

[0173] Terminal WTRU1 may receive a key update response message from terminal WTRU2 confirming that terminal WTRU2 is ready to use the new key in the connection via the second relay.Terminal WTRU1 (and terminal WTRU2) retain the security context used for the initial connection via Relay1.

[0174] Terminal WTRU1 may send a correlation ID in an integrity protected DCR message for terminal WTRU2 to locate new security keys and establish a new connection security using these keys.

[0175] Figure 8 An example of a reselection procedure is illustrated. The second WTRU may receive a link modification request (LMR) message from the first WTRU using the first relay, wherein the LMR message may include a new most significant byte (MSB) of a new key NR ProSe identifier (KNRPID) to be used for the current key. The second WTRU may transmit a link modification accept (LMA) message to the first WTRU using the first relay, wherein the LMA message may include a new least significant byte (LSB) of a new KNRP ID to be used for the current key. The second WTRU may form a new KNRP ID by combining the new MSB and the new LSB. The second WTRU may receive a direct connection request (DCR) message from the first WTRU using the second relay, wherein the DCR message includes a new KNRP ID (e.g., formed by the first WTRU, which matches the new KNRP ID formed by the second WTRU because both use the same new LSB and new MSB to create the new KNRP ID). In one example, prior to receiving the LMR message, the second WTRU may receive a message from the first WTRU over a first connection using a first relay, wherein the first connection is established based on an initial KNRP ID for the current key, wherein the initial KNRPID is different from the new KNRP ID. In one example, the current key is the same at the first WTRU and the second WTRU. In one example, once the new KNRP ID for the current key is generated, the initial KNRP ID for the current key is discarded. In one example, the second WTRU may allocate LSBs based on an initial connection maintenance indication with the LMR message.

[0176] In one example, a WTRU (e.g., communicating with another WTRU via one or more relays) may implement a method for a reselection / selection procedure (e.g., regarding a relay). The WTRU may transmit a request message that may include an indication for including a new most significant byte (MSB) of a current key NR ProSe (KNRP). The WTRU may receive an acceptance message that includes a new least significant byte (LSB) of the current KNRP. The WTRU may transmit a direct connection request with a new KNRP ID, wherein the new KNRP ID is generated by combining the new MSB of the current KNRP and the new LSB of the current KNRP. The WTRU may receive a direct connection acceptance message. The request message may be a link modification request (LMR) message, and the acceptance message may be a link modification accept (LMA) message. The request message may include an indication to maintain a current connection implemented via a first relay. After receiving the direct connection request message, the current connection may be released.

[0177] As described in this document, the following acronyms may be used: Break Before Make (BBM); Break Before Make (MBB); Direct Connection Request / Accept (DCR / DCA); (Root) Key NR ProSe (KNRP); Session Key NR ProSe (KNRP-Sess); Link Modification Request / Accept (LMR / LMA); Least / Most Significant Byte (LSB / MSB); NR ProSe Encryption Key (NRPEK); NR ProSe Integrity Key (NRPIK); Relay Service Code (RSC); and / or UE-to-UE Relay (U2U Relay).

[0178] As described herein, a higher layer may refer to one or more layers in a protocol stack, or a specific sublayer within a protocol stack. A protocol stack may include one or more layers in a WTRU or a network node (e.g., an eNB, a gNB, other functional entities, etc.), each of which may have one or more sublayers. Each layer / sublayer may be responsible for one or more functions. Each layer / sublayer may communicate directly or indirectly with one or more layers in other layers / sublayers. In some cases, these layers may be numbered, such as layer 1, layer 2, and layer 3. For example, layer 3 may include one or more of the following: non-access stratum (NAS), Internet protocol (IP), and / or radio resource control (RRC). For example, layer 2 includes one or more of the following: packet data convergence control (PDCP), radio link control (RLC), and / or medium access control (MAC). For example, layer 3 may include physical (PHY) layer type operations. The higher the number of a layer, the higher the layer is relative to other layers (e.g., layer 3 is higher than layer 1). In some cases, the aforementioned examples may be referred to as layers / sublayers themselves, regardless of the layer number, and may be referred to as higher layers as described herein. For example, from highest to lowest, a higher layer may refer to one or more of the following layers / sublayers: a NAS layer, an RRC layer, a PDCP layer, an RLC layer, a MAC layer, and / or a PHY layer. Any reference to a higher layer in conjunction with a process, device, or system herein will refer to a layer higher than the layer of the process, device, or system. In some cases, references to a higher layer herein may refer to a function or operation performed by one or more layers described herein. In some cases, references to a higher layer herein may refer to information sent or received by one or more layers described herein. In some cases, references to a higher layer herein may refer to a configuration sent and / or received by one or more layers described herein.

[0179] Although features and elements are described above in specific combinations (e.g., embodiments, methods, examples, etc.), it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. For example, as disclosed herein, for illustrative purposes, there may be a method described in conjunction with the accompanying drawings, and it will be understood by those of ordinary skill in the art that one or more features or elements from this method may be used alone or in combination with one or more features from another method described elsewhere. The symbol " / " (e.g., forward slash) may be used herein to represent "and / or", where, for example, "A / B" may imply "A and / or B". As used herein, "one" and similar phrases should be interpreted as "one or more" and "at least one". Any term ending with the suffix "(s)" may be interpreted as "one or more" and "at least one". The term "may" will be interpreted as "for example, may" or indicate that something "does happen" or "may happen". In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as internal hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method implemented by a second wireless transmit receive unit (WTRU), the method comprising: receiving a link modification request (LMR) message from a first WTRU using a first relay, wherein the LMR message includes a new most significant byte (MSB) of a new Key NR ProSe Identifier (KNRP ID) to be used for the current key; transmitting, using the first relay, a Link Modification Accept (LMA) message to the first WTRU, wherein the LMA message includes a new least significant byte (LSB) of the new KNRP ID to be used for the current key; forming the new KNRP ID by combining the new MSB and the new LSB; and A direct connection request (DCR) message is received from the first WTRU using a second relay, wherein the DCR message includes the new KNRP ID.

2. The method of claim 1 , prior to receiving the LMR message, receiving a message from the first WTRU over a first connection using the first relay, wherein the first connection is established based on an initial KNRP ID of the current key, wherein the initial KNRP ID is different from the new KNRP ID.

3. The method of claim 1 , wherein the current key is the same at the first WTRU and the second WTRU.

4. The method of claim 1, wherein once the new KNRP ID for the current key is generated, the initial KNRP ID for the current key is discarded.

5. The method of claim 1, further comprising allocating the LSB based on an initial connection maintenance indication with the LMR message.

6. A second wireless transmit receive unit (WTRU), the second wireless transmit receive unit (WTRU) comprising: means for receiving a link modification request (LMR) message from a first WTRU using a first relay, wherein the LMR message includes a new most significant byte (MSB) of a new Key NR ProSe Identifier (KNRP ID) to be used for a current key; means for transmitting, using the first relay, a link modification accept (LMA) message to the first WTRU, wherein the LMA message includes a new least significant byte (LSB) of the new KNRP ID to be used for the current key; means for forming said new KNRP ID by combining said new MSB and said new LSB; and means for receiving a direct connection request (DCR) message from the first WTRU using a second relay, wherein the DCR message includes the new KNRP ID.

7. The WTRU of claim 6, further comprising means for receiving a message from the first WTRU over a first connection using the first relay prior to receiving the LMR message, wherein the first connection is established based on an initial KNRP ID of the current key, wherein the initial KNRP ID is different from the new KNRP ID.

8. The WTRU of claim 6, wherein the current key is the same at the first WTRU and the second WTRU.

9. The WTRU of claim 6, wherein once the new KNRP ID for the current key is generated, an initial KNRP ID for the current key is discarded.

10. The WTRU of claim 6, further comprising means for allocating the LSB based on an initial connection maintenance indication with the LMR message.

Images