Realization of mobile repeaters for device-to-device (D2D) communications

Abstract

To provide systems, methods, and instrumentalities for a WTRU to act as a mobile relay.SOLUTION: A method comprises: the WTRU connecting to a network; the WTRU receiving a message from the network indicating that the WTRU is to act as a mobile relay for one or more devices outside of a coverage of the network; the WTRU discovering one or more devices outside of the coverage of the network; and the WTRU receiving a message from an out-of-coverage device that indicates that the out-of-coverage device has selected the WTRU to act as a mobile relay.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to the implementation of a mobile repeater for device-to-device (D2D) communication. [Background technology]

[0002] Major standards bodies for wireless communication protocols (e.g., Institute of Electrical and Electronics Engineers (IEEE), third generation partner project (3GPP), etc.) are currently studying supporting direct device-to-device (D2D) communications. For example, for wireless access systems based on 3GPP and Long Term Evolution (LTE), support for D2D communications can enable cost-effective, high-capacity communications using radio waveforms similar to LTE cellular transmissions. The use of LTE-like communications for both network-based communications and D2D communications can help harmonize wireless access technologies across jurisdictions to lower capital expenditures (CAPEX) and operational expenditures (OPEX) of available wireless access technologies for use.

[0003] For example, D2D communications may be utilized to support public safety (PS) type applications. Examples of PS applications may include applications that allow first responders to communicate with each other and other users in areas with or without network coverage. Some PS communications may require higher reliability of transmission than other types of services.

[0004] Furthermore, PS applications may often require support of wireless communication in areas that are not under the radio coverage of LTE networks. For example, the goal may be to ensure support of D2D communication in areas with limited network coverage, such as in tunnels, deep basements, or after a catastrophic system outage. Therefore, D2D protocols may be defined to support D2D communication in the absence of an operational network (or, for example, before the arrival of an ad-hoc deployed wireless infrastructure).

[0005] D2D communications may also be designed to support commercial applications. For example, as the number of connected devices increases, it may be more efficient from a mobile network perspective to allow some communication of commercial and other user data to be exchanged as D2D communications rather than, or in addition to, routing the communications through the mobile network. D2D communications may also facilitate communication of data with stringent Quality of Service (QoS) requirements (e.g., low latency, high reliability, etc.). One exemplary use case relates to commercial wearable devices (e.g., watches, glasses, etc.) configured to wirelessly communicate with other devices (e.g., phones, tablets, computers, mobile networks, etc.).

[0006] The D2D communication protocol may be defined in a flexible manner to support one or more of PS and commercial applications. Summary of the Invention

[0007] Systems, methods, and means are disclosed for a WTRU to act as a mobile relay and / or connect to a mobile relay, e.g., by performing D2D communications and procedures. For example, a WTRU (e.g., a remote WTRU) connecting to a mobile relay may receive transmissions from multiple mobile relays. The remote WTRU may determine a channel quality based on the transmissions. The remote WTRU may determine whether the channel quality of the mobile relay exceeds a set threshold. The set threshold may be based on a required channel quality corresponding to application layer data transmitted from the remote WTRU via the mobile relay. The remote WTRU may rank the mobile relays. The remote WTRU may select a highest ranked mobile relay that supports a service associated with the application layer data. The remote WTRU may send a request to connect with the highest ranked mobile relay. The remote WTRU may connect with the highest ranked mobile relay.

[0008] The remote WTRU may periodically measure the channel quality. The remote WTRU may determine whether the channel quality of the transmission from the mobile repeater to which the remote WTRU is connected exceeds a configured threshold. If the transmission from the mobile repeater to which the remote WTRU is connected no longer exceeds the configured threshold, the remote WTRU may reselect another mobile repeater. The channel quality of the transmission from the reselected mobile repeater may exceed the configured threshold. The channel quality of the transmission from the reselected mobile repeater may become the highest ranked channel quality. The remote WTRU may determine whether the reselected mobile repeater supports a service associated with application layer data. The remote WTRU may disconnect from the previously selected mobile repeater and connect to the reselected mobile repeater. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A. [Figure 1C] A system diagram illustrating an example radio access network and an example core network that may be used within the communication system illustrated in FIG. 1A. [Figure 1D] 1B is a system diagram illustrating another example radio access network and another example core network that may be used within the communications system illustrated in FIG. 1A. [Figure 1E] 1B is a system diagram illustrating another example radio access network and another example core network that may be used within the communications system illustrated in FIG. 1A. [Diagram 2] FIG. 2 illustrates an example WTRU-to-Network Mobile relay function. [Diagram 3] FIG. 1 illustrates an example WTRU to network mobile repeater functionality. [Figure 4] FIG. 1 illustrates an example WTRU to network mobile repeater functionality. [Diagram 5] FIG. 1 illustrates an example of public safety discovery using Model A. [Figure 6] FIG. 13 is a diagram illustrating an example of public safety discovery using Model B. [Figure 7] FIG. 13 illustrates an example of selection of a mobile repeater WTRU. [Figure 8] FIG. 13 shows an example of location-based pre-selection of a mobile repeater WTRU. [Figure 9] FIG. 13 illustrates an example of selection / connection establishment. [Figure 10] FIG. 13 illustrates an example of resource reconfiguration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A detailed description of exemplary embodiments will now be described with reference to various drawings. While this description provides detailed examples of possible implementations, it should be noted that the details are intended to be illustrative and in no way limit the scope of the present application. Furthermore, the drawings may show one or more message charts that are intended to be illustrative. Other embodiments may be used. The order of messages may be changed where appropriate. Messages may be omitted where not necessary, and additional messages may be added.

[0011] 1A is a diagram of 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, broadcasts, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may use 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), and / or the like.

[0012] 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, and / or 102d (which may be referred to generally or collectively as WTRUs 102), a radio access network (RAN) 103 / 104 / 105, a core network 106 / 107 / 109, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although 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, and 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, and 102d may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, consumer electronics devices, and / or the like.

[0013] The communications system 100 may also include a base station 114a and a base station 114b. Each of the base stations 114a and 114b may be any type of device configured to wirelessly interface with one or more of the WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communications networks, such as the core network 106 / 107 / 109, the Internet 110, and / or the network 112. By way of example, the base stations 114a and 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and / or the like. Although the base stations 114a and 114b are each illustrated as a single element, it should be understood that the base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0014] The base station 114a may be part of a RAN 103 / 104 / 105, 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 within a particular geographic area, which may be referred to as a cell (not shown). The cell may be further 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, one transceiver for each sector of the cell. In another embodiment, the base station 114a may use multiple-input multiple-output (MIMO) technology and thus may utilize multiple transceivers for each sector of the cell.

[0015] The base stations 114a and 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, and 102d over an air interface 115 / 116 / 117, which may be any suitable wireless communications link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 115 / 116 / 117 may be established using any suitable radio access technology (RAT).

[0016] More specifically, as mentioned above, the communication system 100 may be a multiple access system and may use one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and / or the like. For example, the base stations 114a and the WTRUs 102a, 102b, 102c in the RAN 103 / 104 / 105 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 Enhanced HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0017] In another 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 115 / 116 / 117 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A).

[0018] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as 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), and / or the like.

[0019] The base station 114b in FIG. 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity within a localized area, such as an office, a home, a vehicle, a campus, and / or 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 another 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, 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. Therefore, the base station 114b may not be required to access the Internet 110 via the core network 106 / 107 / 109.

[0020] The RAN 103 / 104 / 105 may be in communication with a core network 106 / 107 / 109, which may be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, and 102d. For example, the core network 106 / 107 / 109 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 shown in FIG. 1A, it should be appreciated that the RAN 103 / 104 / 105 and / or the core network 106 / 107 / 109 may be in direct or indirect communication with other RANs that use the same RAT as the RAN 103 / 104 / 105 or a different RAT. For example, in addition to being connected to the RAN 103 / 104 / 105, which may utilize E-UTRA radio technology, the core network 106 / 107 / 109 may also be in communication with another RAN (not shown) that uses GSM radio technology.

[0021] The core network 106 / 107 / 109 may also act as a gateway for the WTRUs 102a, 102b, 102c, and 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing 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 Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and IP in the TCP / IP Internet protocol suite. The network 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another core network connected to one or more RANs that may use the same RAT as the RAN 103 / 104 / 105 or a different RAT.

[0022] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communications system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may use a cellular-based radio technology and a base station 114b that may use an IEEE 802 radio technology.

[0023] Figure 1B is a system diagram of an example WTRU 102. As shown in Figure 1B, 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 other peripherals 138. It should be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment. Embodiments also contemplate that the base stations 114a and 114b and / or the nodes they may represent, such as, but not limited to, a transceiver station (BTS), a Node B, a site controller, an access point (AP), a home Node B, evolved home Node B (eNodeB), a home evolved Node B (HeNB or HeNodeB), a home evolved Node B gateway, and a proxy node, among others, may include some or all of the elements shown in FIG. 1B and described herein.

[0024] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple 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) circuit, any other type of integrated circuit (IC), a state machine, and / or 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. Although FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0025] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via the air interface 115 / 116 / 117. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In another embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and receive both RF and light signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0026] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use 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 115 / 116 / 117.

[0027] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, UTRA and IEEE 802.11.

[0028] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from 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). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Additionally, 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 / or 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 home computer (not shown).

[0029] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components within the WTRU 102. The power source 134 may be any suitable device that provides power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and / or the like.

[0030] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding a current location of the WTRU 102. In addition to or in lieu of 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 115 / 116 / 117 and / or determine its location based on the timing of signals received from two or more nearby base stations. It should be appreciated that the WTRU 102 may acquire location information by way of any suitable location determination implementation while remaining consistent with an embodiment.

[0031] 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 photos or videos), 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, and / or the like.

[0032] FIG. 1C is a system diagram of the RAN 103 and the core network 106 according to one embodiment. As mentioned above, the RAN 103 may use UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 115. The RAN 103 may also be in communication with the core network 106. As shown in FIG. 1C, the RAN 103 may include Node Bs 140a, 140b, 140c, each of which may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 115. Each of the Node Bs 140a, 140b, 140c may be associated with a particular cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It should be appreciated that the RAN 103 may include any number of Node Bs and RNCs while remaining consistent with an embodiment.

[0033] As shown in FIG. 1C, the Node Bs 140a, 140b may be in communication with the RNC 142a. Additionally, the Node B 140c may be in communication with the RNC 142b. The Node Bs 140a, 140b, 140c may be in communication with the respective RNCs 142a, 142b via an Iub interface. The RNCs 142a, 142b may be in communication with each other via an Iur interface. Each of the RNCs 142a, 142b may be configured to control the respective Node Bs 140a, 140b, 140c to which it is connected. Additionally, each of the RNCs 142a, 142b may be configured to perform or support other functionalities such as outer loop power control, load control, admission control, packet scheduling, handover control, macro diversity, security functions, data encryption, and / or the like.

[0034] 1C may include a Media Gateway (MGW) 144, a Mobile Switching Center (MSC) 146, a Serving GPRS Support Node (SGSN) 148, and / or a Gateway GPRS Support Node (GGSN) 150. Although each of the foregoing elements is illustrated as part of the core network 106, it should be understood that any one of these elements may be owned and / or operated by an entity other than the core network operator.

[0035] The RNC 142a in the RAN 103 may be connected to an MSC 146 in the core network 106 via an IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and MGW 144 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.

[0036] The RNC 142a in the RAN 103 may also be connected to an SGSN 148 in the core network 106 via an IuPS interface. The SGSN 148 may be connected to a GGSN 150. The SGSN 148 and GGSN 150 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.

[0037] As mentioned above, the core network 106 may also be connected to networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0038] 1D is a system diagram of the RAN 104 and the core network 107 according to one embodiment. As mentioned above, the RAN 104 may use 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 core network 107.

[0039] The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it should be understood 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 receive wireless signals from the WTRU 102a.

[0040] 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 on the uplink and / or downlink, and / or the like. As shown in FIG. 1D, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0041] The core network 107 shown in Figure 1D may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. Although each of the foregoing elements is illustrated as part of the core network 107, it should be understood that any one of these elements may be owned and / or operated by an entity other than a core network operator.

[0042] The MME 162 is connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authentication of users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selection of a particular serving gateway during initial attachment of the WTRUs 102a, 102b, 102c, and / or the like. The MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that use other radio technologies, such as GSM or WCDMA.

[0043] The serving gateway 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The serving gateway 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The serving gateway 164 may also perform other functions, such as anchoring the user plane during inter-eNode B handover, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and / or the like.

[0044] The serving gateway 164 may also be connected to a PDN gateway 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.

[0045] The core network 107 may facilitate communications with other networks. For example, the core network 107 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 core network 107 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the core network 107 and the PSTN 108. Additionally, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0046] 1E is a system diagram of the RAN 105 and the core network 109 according to one embodiment. The RAN 105 may be an Access Service Network (ASN) that uses IEEE 802.16 radio technology to communicate with the WTRUs 102a, 102b, 102c over an air interface 117. As discussed further below, communication links between different functional entities of the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109 may be defined as reference points.

[0047] 1E, the RAN 105 may include base stations 180a, 180b, 180c, and an ASN gateway 182, although it should be understood that the RAN 105 may include any number of base stations and ASN gateways while remaining consistent with an embodiment. The base stations 180a, 180b, 180c may each be associated with a particular cell (not shown) in the RAN 105 and may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 117. In one embodiment, the base stations 180a, 180b, 180c may implement MIMO technology. Thus, the base station 180a, for example, may use multiple antennas to transmit wireless signals to and receive wireless signals from the WTRU 102a. The base stations 180a, 180b, 180c may also provide mobility management functions such as handoff triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QoS) policy enforcement, and / or the like. The ASN gateway 182 may act as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to the core network 109, and / or the like.

[0048] The air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 may be defined as an R1 reference point that implements the IEEE 802.16 specification. Additionally, each of the WTRUs 102a, 102b, 102c may establish a logical interface (not shown) with the core network 109. The logical interface between the WTRUs 102a, 102b, 102c and the core network 109 may be defined as an R2 reference point that may be used for authentication, authorization, IP host configuration management, and / or mobility management.

[0049] The communication link between each of the base stations 180a, 180b, 180c may be defined as an R8 reference point that includes protocols that facilitate WTRU handovers and the transfer of data between base stations. The communication link between the base stations 180a, 180b, 180c and the ASN gateway 182 may be defined as an R6 reference point. The R6 reference point may include protocols that facilitate mobility management based on mobility events associated with each of the WTRUs 102a, 102b, 102c.

[0050] As shown in FIG. 1E, the RAN 105 may be connected to a core network 109. The communication link between the RAN 105 and the core network 109 may be defined as an R3 reference point including protocols facilitating, for example, data forwarding and mobility management capabilities. The core network 109 may include a Mobile IP Home Agent (MIP-HA) 184, an Authentication, Authorization, and Accounting (AAA) server 186, and a gateway 188. Although each of the foregoing elements is illustrated as part of the core network 109, it should be understood that any one of these elements may be owned and / or operated by an entity other than the core network operator.

[0051] The MIP-HA may be responsible for IP address management and may enable the WTRUs 102a, 102b, 102c to roam between different ASNs and / or different core networks. The MIP-HA 184 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 AAA server 186 may be responsible for user authentication and support of user services. The gateway 188 may facilitate interworking with other networks. For example, the gateway 188 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. Additionally, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0052] Although not shown in FIG. 1E, it should be understood that the RAN 105 may be connected to other ASNs and the core network 109 may be connected to other core networks. The communication link between the RAN 105 and the other ASNs may be defined as an R4 reference point, which may include protocols to coordinate mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs. The communication link between the core network 109 and the other core networks may be defined as an R5 reference point, which may include protocols to facilitate interworking between a home core network and a visited core network.

[0053] Public Safety (PS) type applications (e.g., among first responders) can include direct push-to-talk voice services using one or more talkgroups. PS type applications can take advantage of LTE broadband radio, per-service capabilities such as video push or video download.

[0054] Once deployed, D2D communication may be available for PS type applications and commercial use cases. One exemplary commercial use case may be that of a utility company that requires support for bidirectional wireless communication in areas not covered by network infrastructure. D2D services, such as D2D discovery procedures, may be defined to include appropriate signaling mechanisms to enable proximity-based services and / or traffic offload using LTE-based radio access in commercial use cases.

[0055] Examples of commercial use cases may include wearable use cases, Internet of Things (IoT) use cases, and / or machine type communication (MTC) use cases. For example, a user may use a handheld device (e.g., a smartphone) as a mobile repeater for traffic of one or more wearable devices (e.g., a watch, glasses, etc.). The wearable device may be in relatively close proximity to the mobile repeater device. The wearable device may be configured to communicate with a network and / or other devices in an energy-efficient manner. The wearable device may communicate via a handheld device such as a WTRU. The handheld device / WTRU may act as a unidirectional mobile repeater and / or a bidirectional mobile repeater. For example, when the WTRU is acting as a unidirectional mobile repeater, the wearable device may receive downlink communications directly from an eNB and / or other mobile network nodes. The wearable device may transmit an uplink via the unidirectional mobile repeater / WTRU. By communicating via a mobile repeater on the uplink, power of transmission may be saved. This is because mobile repeaters are likely to be in closer proximity to the wearable device than the mobile network nodes. The wearable device can communicate with the network via mobile repeaters at the edge of eNB coverage. The wearable device can be equipped with a radio that may or may not be designed to have the same sensitivity as the mobile repeater's radio.

[0056] A signaling mechanism may be used to enable multiple remote WTRUs to communicate through the mobile repeater WTRU such that the mobile repeater can efficiently communicate with multiple wearables. The mobile repeater WTRU may manage multiple wearables. The wearable may be a smart watch along with other smart devices. For example, the smart devices may be Google Glass, a hands-free headset, a handheld gaming device, and / or the like.

[0057] In an example IoT or MTC use case, millions (or more) devices may be connected to the network. Some or all of the devices in the IoT or MTC use case may be relatively low-cost and / or capability-limited devices. The devices may be configured to communicate in an energy-efficient manner. The devices may attempt to connect to the network simultaneously, which may cause congestion. Connecting through a mobile repeater device may avoid some of the problems associated with connecting to the network simultaneously. The mobile repeater device may comprise a mobile repeater WTRU. Some or all of the devices may have little or no coverage of the eNB. Some or all of the devices may be in close proximity to the WTRU. For example, the WTRU may act as a mobile repeater, e.g., to extend network coverage.

[0058] A signaling mechanism may be used to enable one or more remote WTRUs to communicate via a mobile repeater WTRU. In an example IoT or MTC use case, the number of remote WTRUs may be expected to be huge. The remote WTRUs may be connected to the mobile repeaters such that the directional connection of the devices with the network may be reduced. Efficient association / reassociation may be designed to attempt to achieve a relatively equal distribution of remote WTRUs to the mobile repeaters. Unnecessarily configuring a WTRU as a mobile repeater may be avoided. Proper service continuity to the network and / or among the mobile repeaters may be maintained.

[0059] The mobile repeater WTRU may communicate with the remote WTRU using a 3GPP RAT and / or a non-3GPP RAT (e.g., WiFi, Bluetooth, and / or the like). The link between the mobile repeater WTRU and the remote WTRU may be PC5. The communication may be via D2D. The D2D may be via a PC5 interface. The communication may be via D2D adapted to support vehicle-to-vehicle (V2V), low-cost wearables, and / or the like. Narrowband IOT (NB-IOT) waveforms, RATs, and / or the like may be used to support low-cost or low-power devices. The low-cost or low-power devices may communicate via a non-3GPP RAT. The PC5 link may be via a licensed or unlicensed spectrum.

[0060] The link between the mobile repeater WTRU and the eNB may be Uu. The link may comprise an LTE Uu RAT. The link may be over a 3GPP RAT, such as NB-IoT, eMTC, future 5G (NR), and / or the like. The link may be over a non-3GPP RAT, such as WiFi. The Uu link may be over a licensed or unlicensed spectrum.

[0061] The mobile repeater WTRU may implement functionality at a layer of a protocol stack. The mobile repeater may be a Layer 2 (L2) repeater implemented at the MAC layer, the RLC layer, or the PDCP layer. The mobile repeater may be an IP repeater or above an IP repeater.

[0062] Standardization of D2D communications by 3GPP was completed in Release 12 (R12) of the LTE standard. For example, the R12 standardization efforts focused on direct communications between WTRUs and the open discovery procedure of proximity-based services (ProSe). The use of D2D communications for mobile repeaters may be explored to enhance to allow a WTRU to act as a mobile repeater for out-of-coverage WTRUs. As an example, consider two types of mobile repeaters: 1) WTRU-to-network mobile repeaters and 2) WTRU-to-WTRU mobile repeaters. A mobile repeater WTRU may be considered a WTRU-to-network mobile repeater by being configured to act as a mobile repeater between an eNB (e.g., and / or any other mobile network infrastructure node, other RAN nodes, etc.) and a remote WTRU. The remote WTRU may or may not be out of coverage of an eNB and / or other network infrastructure. A mobile repeater WTRU may be considered a WTRU-to-WTRU mobile repeater by being configured to facilitate communication between two or more remote WTRUs. Multiple remote WTRUs can communicate with each other D2D when they are out of range / proximity of each other.

[0063] 2 illustrates an exemplary WTRU-to-network mobile repeater (e.g., mobile repeater) deployment. Functionality may include mobile repeater support of unicast traffic (e.g., uplink (UL) and downlink (DL)) between an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a remote WTRU not served by the network, and / or support bidirectional traffic. For example, the WTRU-to-network mobile repeater 202 (e.g., mobile repeater) may provide a Layer 3 (L3) forwarding function that may relay some and / or all types of IP traffic related to public safety and / or commercial communications. The WTRU-to-network mobile repeater 202 (e.g., mobile repeater) may provide other types of communications between the eNB 204 and the remote WTRU 210. The WTRU-to-network mobile repeater 202 may provide a Layer 2 (L2) relay-and-forwarding function and forward packets at the layer of communications between the eNB 204 and the remote WTRU 210. For example, the WTRU-to-network mobile repeater 202 may communicate with the eNB 204 to send and / or receive data to an application server (AS) 208 (e.g., via the EPC 206). The data may be forwarded to and / or communicated on behalf of a remote WTRU 210 (e.g., which may be outside of network coverage). The WTRU-to-network mobile repeater 202 may communicate with the WTRU 210 (e.g., a remote WTRU) via a PC5 interface. The WTRU-to-network mobile repeater 202 may communicate with the eNB 204 via a Uu interface. The EPC 206 may communicate with the AS 208 (e.g., an AS for public safety and / or commercial communications) via an SGi interface. The example shown in FIG. 2 may include a public safety communication application server and / or a commercial communication application server.

[0064] 3 illustrates an example WTRU-to-network mobile repeater communication exchange. For example, the mobile repeater WTRU 302 may attach to a network at 304 if the mobile repeater WTRU 302 is not already attached to the network. The mobile repeater WTRU 302 may establish a PDN connection at 304. The packet data network (PDN) connection may be used to communicate traffic to / from the remote WTRU 316. For example, a suitable PDN connection in the mobile repeater may not yet exist / be configured for the remote WTRU 316. With respect to IPv6, the mobile repeater WTRU 302 may obtain an IPv6 prefix, such as via a prefix delegation function from the network (e.g., as defined in 3GPP Technical Specification (TS) 23.401).

[0065] The remote WTRU 316 may perform discovery of the mobile repeater WTRU 302 at 306 using a discovery procedure, e.g., Model A discovery and / or Model B discovery. For example, Model A discovery may include an announcement and Model B discovery may include a solicitation and a response. The remote WTRU 316 may select 308 the mobile repeater 302 and establish a connection for one-to-one communication with the mobile repeater 302. The establishment of the connection for one-to-one communication may or may not involve EPC involvement as determined by the SA3 at 314. The EPC involvement may comprise the MME 318 or a home subscriber server (HSS) 320.

[0066] For IPv6, over PC5, the remote WTRU 316 may perform 310 IPv6 stateless address autoconfiguration. The remote WTRU 316 may send 310 a Router Solicitation (RS) message to the network using the mobile repeater's Layer 2 ID as the destination Layer 2 ID. The remote WTRU 316 may solicit 310 a Router Advertisement (RA) message (e.g., as specified in accordance with Internet Engineering Task Force Reason for Collaboration (IETF RFC) 4862). The RA message may include the assigned IPv6 prefix. After the remote WTRU 316 receives the RA message, it may configure 310 a full IPv6 address via IPv6 stateless address autoconfiguration (e.g., according to IETF RFC 4862).

[0067] For IPv4, over PC5, the remote WTRU 316 may use Dynamic Host Configuration Protocol (DHCP) v4. The remote WTRU 316 may send a DHCPv4 discovery message at 312 using the mobile repeater's Layer 2 ID as the destination Layer 2 ID. The mobile repeater WTRU 302 may act as a DHCPv4 server and send a DHCPv4 offer with the assigned remote WTRU IPv4 address at 312. When the remote WTRU 316 receives the lease offer, it may send a DHCP REQUEST message at 312 including the received IPv4 address. The mobile repeater WTRU 302 acting as a DHCPv4 server may send a DHCP ACK message including the lease duration (e.g., configuration information that the client may have requested) to the remote WTRU 316. Upon receiving the DHCP ACK message at 312, the remote WTRU 316 may complete the TCP / IP configuration process.

[0068] 4 illustrates an example WTRU-to-network mobile repeater procedure. This procedure may be used by a ProSe-enabled WTRU (e.g., a remote WTRU 420) to request the mobile repeater 402 to start monitoring for availability of a Temporary Mobile Group Identity (TMGI). The mobile repeater 402 may broadcast the TMGI on a broadcast channel, for example, when it is detected on a multicast control channel (MCCH) of a serving cell (e.g., a cell of the network 422). eMBMS traffic related to this TMGI may also be forwarded to the remote WTRU 420 served by the mobile repeater 402 via a one-to-multiple link (e.g., identified by a specific Layer 2 Group ID provided by the ProSe mobile repeater 402 when this procedure is performed), if available.

[0069] If the remote WTRU 420 successfully discovers the mobile repeater 402 and obtains the TMGI from the group communication application (e.g., after a one-to-one communication session with the mobile repeater 402), the WTRU may use the TMGI to receive relevant broadcast (e.g., eMBMS) content at 404. The relevant broadcast content may be available (e.g., in the eNB). The WTRU may obtain the TMGI in which it is interested by static configuration or by interaction with the group communication application. This interaction may occur before or after the WTRU associates with the mobile repeater 402.

[0070] The WTRU may send 406 a TMGI monitoring request to the mobile repeater 402, where TMGI is the value obtained herein. The mobile repeater 402 may acknowledge receipt of the request herein with a TMGI monitoring response (e.g., layer 2 group ID_traffic, TMGI_Monitoring_Refresh Timer, and / or the like) at 408. The layer 2 group ID_traffic may be used to forward eMBMS content related to the TMGI value received herein to the remote WTRU. The TMGI_Monitoring_Refresh Timer may be configurable in the mobile repeater 402. The TMGI_Monitoring_Refresh Timer may be provided to the WTRU at 408 such that when the timer elapses, the WTRU can perform a TMGI monitoring request procedure (e.g., if it is still configured to monitor the TMGI). At 408, if the remote WTRU 420 does not perform a TMGI monitoring request procedure and no other WTRU performs a TMGI refresh procedure when the TMGI_Monitoring_Refresh Timer expires in the mobile repeater 402, the mobile repeater 402 may stop monitoring the TMGI and / or may stop forwarding associated content when the TMGI_Monitoring_Refresh Timer expires in the mobile repeater 402.

[0071] The ProSe mobile repeater 402 may detect 410 the TMGI that it has requested monitoring. Upon detection of the TMGI at 410, the mobile repeater 402 may broadcast the availability of the TMGI by sending a TMGI announcement message over a broadcast channel at 412. The mobile repeater 402 may broadcast the availability of the TMGI by sending 412 the TMGI announcement message over a broadcast channel (e.g., repeatedly with a configurable repetition interval). The repetition interval may be shorter than the TMGI_Monitoring_Refresh Timer. The value of the TMGI may be used by devices that discover the mobile repeater 402 as a criteria criterion for mobile repeater selection (e.g., if they are interested in the TMGI that the mobile repeater 402 is advertising).

[0072] The WTRU may detect 414 the TMGI announcement and may begin receiving broadcast content on the PC5 point-to-multipoint link associated with the layer-2 group ID_traffic and may release the unicast distribution leg if used. Upon detection of loss of TMGI, the mobile repeater 402 may stop broadcasting the availability of TMGI at 416. The ProSe mobile repeater 402 may send a proactive indication of loss of TMGI to accelerate detection of TMGI loss at the WTRU. The WTRU may request 416 a unicast distribution leg from the group communication AS. The group communication may include public safety or commercial communication. The WTRU may stop receiving broadcast content on the PC5 point-to-multipoint signaling link associated with the group layer-2 ID_traffic at 418.

[0073] FIG. 5 illustrates an example public safety discovery according to Model A. In FIG. 5, the type may be announcement. The discovery type may be mobile repeater discovery. Announcing WTRU-1 502 may send a message to monitoring WTRUs 504-510. The message sent at 502 may comprise information such as type, discovery type, PLMN ID, connection information, ProSe mobile repeater WTRU ID, status, group information, and / or the like. Some or all of the monitoring WTRUs 504-510 may receive messages 512-518. For example, WTRU-2 504 may receive message 1 512.

[0074] FIG. 6 illustrates an exemplary public safety discovery according to Model B. The discoverer WTRU-1 at 602 may send messages to the discoveree WTRUs at 604-610. The messages 1-4 sent at 612-618 may comprise information type, discovery type, PLMN ID, connection information, ProSe mobile repeater WTRU ID, status, group information, and / or the like. In FIG. 6, the type may be solicitation. The discovery type may be mobile repeater discovery. Some or all of the discoverees at 604-610 may send messages back to the discoverer WTRU-1 at 602. For example, in FIG. 6, the discoveree at 604 and the discoveree at 606 may send messages back to the discoverer at 602. The messages 5-6 sent at 620-622 may comprise an information type, a discovery type, a PLMN ID, connection information, a ProSe mobile repeater WTRU ID, a status, group information, and / or the like. In the messages 5-6 sent at 620-622, the type may be a response. The discovery type may be a mobile repeater discovery.

[0075] The following parameters may be used for the example WTRU-to-network mobile repeater discovery shown in FIG. 6: Mobile repeater WTRU ID may be a link layer identifier. The link layer identifier may be used for direct communication. The link layer identifier may be associated with a PDN connection established by the mobile repeater. Public Land Mobile Network (PLMN) ID may identify the PLMN for which radio frequency is used on the link to which the remote WTRU belongs. Radio frequencies may be shared among multiple PLMNs. Radio frequencies may or may not be allocated to a PLMN. The selection of the PLMN ID may be configured by the Home PLMN (HPLMN). Connection information may comprise parameters that identify the connection the mobile repeater provides (e.g., including APN information). A status / maintenance flag may be used to indicate if the mobile repeater is temporarily without connection and / or has low battery (e.g., so that the remote WTRU can seek / reselect another mobile repeater). Group information may comprise information regarding the group the mobile repeater is relaying on.

[0076] Several complications / difficulties may be associated with the use of D2D communications to achieve a mobile repeater function (e.g., WTRU-network mobile repeater and / or WTRU-WTRU mobile repeater). For example, a remote WTRU may be served by a mobile repeater (e.g., a mobile repeater WTRU). The remote WTRU may not be known to the eNB serving the mobile repeater. The remote WTRU may not be able to receive system information from the eNB. The remote WTRU may not be able to correctly select a mobile repeater WTRU and / or an optimal mobile repeater WTRU (e.g., from a device and / or network perspective). The mobile repeater WTRU may be able to serve the remote WTRU. For example, the correct selection of a mobile repeater WTRU may relate to lower layer signal quality and / or application layer services. The mobile repeater WTRU and / or the remote WTRU may be mobile. The remote WTRU may be able to reselect a different mobile repeater WTRU when the mobile repeater WTRU to which the remote WTRU is connected is no longer able to serve as its mobile repeater.

[0077] In addition to mobile repeater selection / reselection, current resource allocation rules developed for D2D (e.g., in R12) may be inappropriate and / or suboptimal for mobile repeaters. For example, a remote WTRU may be out of coverage and may be configured to use pre-configured resources for direct communication when out of coverage. Use of pre-configured resources for direct communication may result in over-utilization of pre-configured resources when multiple remote WTRUs and mobile repeater WTRUs are co-located in a zone (e.g., out-of-coverage zone).

[0078] The resource usage rules defined for direct D2D communication may be inefficient for mobile repeater scenarios. The eNB may not be able to control the resources that may be used by the remote WTRU when the R12 rules are applied. For example, the R12 rules may lack support for service continuity for scenarios involving mobile repeaters (e.g., mobile repeater mobility and / or remote WTRU mobility between mobile repeaters). For example, the remote WTRU may enter and / or leave the area covered by the eNB, which may affect resource utilization for D2D communication. The R12 rules do not provide a way in which switching of the remote WTRU between an area covered by the eNB and an area not covered by the eNB is transparent to the application layer. The mobile repeater WTRU may lose coverage with respect to the eNB, and the remote WTRU served by that mobile repeater WTRU may or may not be able to maintain service upon loss of connection.

[0079] A WTRU attempting to connect to a mobile repeater may perform one or more autonomously determined actions to select a mobile repeater and / or receive instructions from a network entity to select a mobile repeater. For example, a remote WTRU may be configured to perform mobile repeater WTRU selection and reselection procedures and to perform measurements that may be used to support these selection / reselection procedures. The remote WTRU, mobile repeater WTRU, and / or eNB may perform procedures associated with mobile repeater initiation based on control of the associated eNB. The mobile repeater WTRU, remote WTRU, and / or eNB may perform procedures to allocate resources for communication between the mobile repeater WTRU and the remote WTRU. The mobile repeater WTRU, remote WTRU, and / or eNB may perform procedures to handle service continuity, e.g., during remote WTRU mobility between mobile repeaters and / or mobile repeater mobility between eNBs.

[0080] The WTRU may perform a mobile repeater selection / reselection process to select a mobile repeater to connect to a service (e.g., one-to-one communication, eMBMS, etc.) and perform associated measurements that may be provided to upper layers to perform the mobile repeater selection / reselection process. This process may apply when the WTRU is out-of-coverage and / or in-coverage. This process may apply when the WTRU is transitioning from in-coverage to out-of-coverage. For example, the initial mobile repeater selection may be performed in the application layer with assistance information (e.g., measurements) from lower layers. Examples described herein may use the term remote WTRU to refer to a WTRU connected to a mobile repeater and / or a WTRU that has attempted to connect to a mobile repeater. A mobile repeater may be referred to as a mobile repeater WTRU.

[0081] A lower layer (e.g., physical (PHY), medium access control (MAC), or radio resource control (RRC)) can report measurements made on a mobile repeater transmission to a higher layer. The measurements may be made on one or more of a demodulation reference signal (DMRS) on a sidelink synchronization channel (SL-SCH), a DMRS on a physical sidelink broadcast channel (PSBCH), a device-to-device synchronization signal (D2DSS), discovery resources, and / or the like.

[0082] A lower layer in the remote WTRU may report measurements of received transport blocks. For example, a lower layer in the WTRU may report measurements of received transport blocks. A lower layer in the WTRU may report a list of some or all of the measurements taken. A lower layer may report an averaged measurement report for multiple transport blocks over a given period of time. Measurements may be sent periodically to upper layers or may be provided to upper layers when requested by upper layers.

[0083] The measurements reported to higher layers may include one or more of a channel quality measurement (e.g., Reference Signal Received Power (RSRP)) and / or a mobile repeater ID. The mobile repeater ID may correspond to an ID retrieved from the PSBCH. The mobile repeater ID may correspond to a Layer 1 ID decoded in a system aspect (SA). The mobile repeater ID may correspond to an L2 WTRU ID. The mobile repeater ID may correspond to an ID decoded in a MAC header. For example, the mobile repeater ID may correspond to an ID decoded in a MAC header if the measurement is taken from a data packet. The measurements may enable association of a channel quality measurement to a mobile repeater ID corresponding to a given mobile repeater.

[0084] A mobile repeater may be selected based on selection criteria and other information. The mobile repeater selection criteria may include one or more of announced services (e.g., connection information), announced PLMN ID, TMGI, and mobile repeater specific information. The mobile repeater selection may use measurements provided by lower layers and / or one or more thresholds associated with the measurements. The associated thresholds may be provided in the application layer and / or by lower layers. The associated thresholds may be provided as part of the RRC configuration. FIG. 7 is a diagram of an example of mobile repeater WTRU selection.

[0085] The remote WTRU may receive a Model A mobile repeater announcement and / or a Model B response from one or more mobile repeaters WTRUs. For example, as shown in FIG. 7, the remote WTRU 718 receives a mobile repeater announcement from a mobile repeater WTRU1 702 at 704. The remote WTRU 718 receives a mobile repeater announcement from a mobile repeater WTRU2 720 at 706. The mobile repeater announcements of 704 and 706 may be Model A mobile repeater announcements and / or Model B responses. The mobile repeater announcements may include an indication of services provided or supported by the mobile repeater WTRU. For example, the mobile repeater announcements may include an indication that the mobile repeater WTRU supports one or more services requested by the remote WTRU 718. The mobile repeater announcements may include an indication of the PLMN serving the mobile repeater WTRU. For example, the mobile repeater announcement may include an indication that the mobile repeater WTRU is associated with one or more PLMNs to which the remote WTRU 718 is allowed to connect.

[0086] An application layer associated with the remote WTRU may filter 708 resources including services used by the remote WTRU. An application layer associated with the remote WTRU may filter 708 responses for which the remote WTRU may be allowed on the PLMN. The remote WTRU may filter 708 mobile repeater candidates according to a configured threshold. The remote WTRU may compare measurements from the mobile repeater announcements to one or more configured thresholds. The remote WTRU may rank 708 mobile repeaters whose channel quality exceeds a configured threshold according to measurements and / or quality (e.g., channel quality). The ranking may be based on mobile repeaters WTRUs that support services used by the WTRU and that have signal quality above a configured threshold. The remote WTRU 718 may select a mobile repeater 708. For example, the remote WTRU may select a ranked mobile repeater that supports certain services and meets certain quality criteria. The ranked mobile repeater may be the mobile repeater with the highest ranking. The ranking may be based on received signal strength and / or signal quality (e.g., having the highest strength and / or highest ranked signal quality). The remote WTRU may initiate a connection establishment to the selected mobile repeater. The remote WTRU may send 710 a connection request to the selected mobile repeater. The selected mobile repeater may send 712 a mobile relay request to the eNB 722. The eNB may send 714 a mobile relay accept to the selected mobile repeater 702. The selected mobile repeater 702 may send 716 a connection accept to the remote WTRU 718.

[0087] A connection failure may occur. In the event of a connection failure, the remote WTRU may select the next ranked mobile repeater and attempt a connection establishment process. A mobile repeater connection establishment failure may occur. A mobile repeater connection establishment failure may occur when a secure link with the mobile repeater WTRU cannot be established due to an authentication and / or security association failure. A mobile repeater connection establishment failure may occur when a valid TMGI for broadcast cannot be successfully obtained. A mobile repeater connection establishment failure may occur when the remote WTRU may not be able to receive the broadcast of the TMGI. For example, the remote WTRU may not be able to receive the broadcast of the TMGI due to authentication and / or permission reasons. A mobile repeater connection establishment failure may occur when the eNB may reject the remote WTRU's connection with the mobile repeater. For example, the eNB may reject the remote WTRU's connection with the mobile repeater due to the mobile repeater not being capable of supporting resources for the requested service. The eNB may reject a remote WTRU's connection with a mobile repeater due to the availability of other mobile repeaters. The eNB may reject the connection and provide a redirection message. The rejection may be sent by the eNB to the remote WTRU via the mobile repeater when the connection is rejected by the eNB. For example, a Uu connection may be used to first send the rejection to the mobile repeater WTRU. The mobile repeater WTRU may forward the rejection to the remote WTRU. The rejection may be sent directly to the remote WTRU by the eNB via the Uu interface. For example, the rejection may be sent directly to the remote WTRU by the eNB via the Uu interface when the remote WTRU is potentially in the coverage of the eNB. The connection accept may be sent directly to the remote WTRU by the eNB via the Uu interface when the eNB determines that the remote WTRU is potentially in the coverage of the eNB.

[0088] The remote WTRU may perform a mobile repeater reselection procedure. The remote WTRU may perform autonomous selection / reselection. To perform autonomous mobile repeater reselection, the remote WTRU may periodically perform an evaluation of the signal quality of the mobile repeater WTRU to which the remote WTRU is connected. The remote WTRU may initiate the reselection procedure when one or more of certain conditions are satisfied. The remote WTRU may initiate the reselection procedure when the signal quality of the mobile repeater WTRU to which the remote WTRU is connected is below a set threshold. For example, the remote WTRU may initiate the reselection procedure when the WTRU no longer detects the mobile repeater. The signal quality of the mobile repeater WTRU to which the remote WTRU is connected may be determined using one or more of the measurements described herein.

[0089] The remote WTRU may measure the signal quality of the mobile repeater WTRU to which the remote WTRU is connected based on a Model A or Model B discovery message. For example, the remote WTRU may measure the signal quality of the mobile repeater WTRU to which the remote WTRU is connected based on a Model A or Model B discovery message. The remote WTRU may measure the signal quality by triggering a Model B response message. The remote WTRU may be configured to periodically send a Model B request to trigger a Model B response message from the serving mobile repeater. For example, the remote WTRU may derive the signal quality measurement from the Model B response message from the serving mobile repeater. The remote WTRU may obtain its signal quality measurement directly from the SL-SCH or SL-BCH of the mobile repeater WTRU.

[0090] The remote WTRU may initiate a reselection procedure when the mobile repeater WTRU has not announced the services used and / or required by the WTRU. The remote WTRU may initiate a reselection procedure when one or more other candidate mobile repeaters WTRU have announced the services utilized by the remote WTRU. The remote WTRU may initiate a reselection procedure when a signal quality measurement of the other candidate mobile repeater exceeds a set threshold. The remote WTRU may initiate a reselection procedure when a signal quality measurement of the other candidate mobile repeater is better than a signal quality measurement of the mobile repeater WTRU to which the remote WTRU is connected. For example, the remote WTRU may perform reselection when the signal quality of one or more candidate mobile repeaters may be better than the signal quality measurement of the current mobile repeater WTRU by a given offset. The remote WTRU may perform reselection when the signal quality of one or more candidate mobile repeaters may be better than the signal quality measurement of the mobile repeater WTRU for a given time period. The remote WTRU may perform reselection when the signal quality of one or more candidate mobile repeaters is likely to be better than the mobile repeater WTRU's signal quality measurement by a given offset for a given period of time. The remote WTRU may initiate the reselection procedure when a mobile repeater redirection message is received.

[0091] The autonomous mobile repeater selection / reselection may comprise one or more actions. When one or more of the conditions that trigger the remote WTRU to initiate a reselection procedure are satisfied and / or other triggers are satisfied, the remote WTRU may trigger the higher layers to perform one or more of certain actions. The remote WTRU may trigger the higher layers to initiate a discovery monitoring process if the discovery monitoring process is stopped. The discovery monitoring process may be Model A or Model B. The remote WTRU may trigger the higher layers to initiate the remote WTRU to send a new Model B solicitation message. For example, the remote WTRU may trigger the higher layers to initiate the remote WTRU to send a new Model B solicitation message to discover other mobile repeaters that can support the requested service. The remote WTRU may trigger the higher layers to initiate the lower layers to perform updated measurements / quality associated with the detected potential mobile repeater WTRU. The remote WTRU may send updated measurements / quality associated with potential mobile repeaters WTRUs to the upper layers. For example, measurements may be made on one or more of the channels or signals described herein. The remote WTRU may trigger the upper layers to perform a mobile repeater selection procedure based on the provided measurements and advertised services for a given mobile repeater. If the lower layers support targeted measurements, the remote WTRU may trigger the lower layers to perform targeted measurements of the mobile repeater that first responded to the Model B solicitation message or for which a Model A message of the given mobile repeater was received. The remote WTRU may trigger the lower layers to perform targeted measurements via the application layer. A list of mobile repeaters WTRUs may be provided to the lower layers.For example, a list of mobile repeater WTRUs may be provided to the lower layer as a list of L2 IDs. The lower layer may return corresponding measurements of one or more of the identified WTRUs.

[0092] The autonomous mobile repeater selection / reselection may comprise various further actions. The mobile repeater WTRU selection or reselection may or may not be successful. For example, if the mobile repeater reselection is unsuccessful, a mobile repeater redirection message may be received. The WTRU may perform one or more actions upon receipt of the mobile repeater redirection message. For example, the remote WTRU may perform one or more of certain actions before moving to a new mobile repeater upon receipt of the mobile repeater redirection message.

[0093] For example, upon receiving a mobile repeater redirection action, the remote WTRU may verify that the proposed mobile repeater is part of a ranked list of mobile repeaters. The WTRU may verify that the proposed mobile repeater satisfies selection criteria (e.g., supports the service requested by the WTRU and / or has a channel quality exceeding a threshold). For example, if the proposed mobile repeater is not part of the ranked list of mobile repeaters, the remote WTRU may remain connected to its current mobile repeater. If the proposed mobile repeater is part of the ranked list of mobile repeaters and satisfies the selection criteria, the remote WTRU may initiate mobile repeater selection to the proposed mobile repeater. The remote WTRU may perform a connection establishment procedure with the proposed mobile repeater.

[0094] When deciding to reselect to a candidate Mobile Repeater, the remote WTRU may perform one or more actions. For example, when deciding to reselect to a candidate Mobile Repeater, the remote WTRU may tear down a connection with the Mobile Repeater to which the remote WTRU is currently connected. When deciding to reselect to a candidate Mobile Repeater, the remote WTRU may initiate a connection establishment to the reselected candidate Mobile Repeater.

[0095] In one example, when deciding to reselect to a candidate Mobile Repeater rather than releasing the connection to the current Mobile Repeater, the remote WTRU may maintain the connection to the current Mobile Repeater while simultaneously attempting a connection establishment procedure with the reselected candidate Mobile Repeater. The remote WTRU may release the connection to the Mobile Repeater to which the remote WTRU is connected when the remote WTRU has successfully established a connection with the reselected candidate Mobile Repeater. The connection to the Mobile Repeater to which the remote WTRU is connected may be released after the remote WTRU has verified that the remote WTRU has started receiving service from the reselected candidate Mobile Repeater. For example, the service may be over eMBMS.

[0096] Autonomous mobile repeater selection / reselection may be supported. Reselection may be supported by various layers. For example, reselection may be supported by the remote WTRU upper layers (e.g., application layers). As an example, the WTRU may be configured to perform measurements of the mobile repeaters to which the remote WTRU is connected continuously (e.g., regularly or relatively continuously, at set intervals, etc.). For example, the remote WTRU upper layers may configure continuous measurements of the mobile repeaters to which the remote WTRU is connected. The upper layers may request the lower layers to send measurements associated with the currently connected mobile repeater and / or the mobile repeater transmitting a measurable signal. The upper layers may configure the lower layers to measure one or more other mobile repeaters, which may be identified by a mobile repeater ID. When the remote WTRU has successfully connected to the mobile repeater WTRU, the upper layers in the remote WTRU may configure measurements to be performed by the lower layers on the mobile repeater. When requested by the upper layers, the lower layers may stop collecting measurements on the SL-SCH for a particular mobile repeater ID. For example, the upper layers may request the lower layers to stop collecting measurements on the SL-SCH for the mobile repeater ID when the remote WTRU terminates its connection to the mobile repeater.

[0097] With regard to autonomous mobile repeater selection / reselection, the remote WTRU may inform the eNB about the identity of the selected mobile repeater. For example, the mobile repeater selection / reselection may occur while the remote WTRU is still within the coverage of the eNB. The selection / reselection may occur autonomously. The WTRU may inform the eNB about the identity of the selected mobile repeater. The WTRU may inform the eNB about relevant information regarding the selected mobile repeater. The relevant information regarding the selected mobile repeater may include one or more of the mobile repeater identification information (e.g., mobile repeater L2 ID, PHY layer ID, and / or the like), the identity of the eNB to which the mobile repeater is connected, the measured signal quality of the mobile repeater (e.g., PC5 measurements), the access point name (APN) or connection information broadcast by the mobile repeater, and / or the signal quality of the Uu link between the mobile repeater and the eNB. Informing the eNB may occur via Uu and / or via the mobile repeater. Reselection of a mobile repeater may be indicated to the eNB to inform the eNB about the reselected mobile repeater. An indication of a reselected and reselected mobile repeater may occur periodically. An indication of a reselected and reselected mobile repeater may occur when a measured PC5 link quality with a selected mobile repeater degrades. The WTRU may inform the eNB about the reselected and reselected mobile repeater (e.g., information of the reselected mobile repeater) upon connection establishment with the mobile repeater.

[0098] Reselection to a new mobile repeater may be triggered by the eNB. Reselection may be triggered by the eNB based on measurements, e.g., measurements reported by the remote WTRU. To facilitate eNB-based mobile repeater reselection, measurements of the remote WTRU by the mobile repeater WTRU may be performed and sent to the eNB. The remote WTRU may make measurements of the PC5 link and send the measurements of the PC5 link to the eNB via the mobile repeater WTRU. The remote WTRU may make measurements of the PC5 link and send the measurements of the PC5 link directly to the eNB when a connection between the remote WTRU and the eNB is available (e.g., the remote WTRU is in coverage). The remote WTRU may indicate to the mobile repeater WTRU that the measurements should be sent to the eNB (e.g., via the mobile repeater WTRU) using an indication that indicates to the mobile repeater WTRU that the measurements are intended to be sent to the eNB. For example, measurements intended for the eNB may be sent to the mobile repeater WTRU using a dedicated message indicating that the measurements are intended for the eNB. The mobile repeater WTRU may perform measurements of the PC5 link between the mobile repeater and the remote WTRU and send the measurements of the PC5 link between the mobile repeater and the remote WTRU to the eNB.

[0099] The eNB or mobile repeater WTRU may send a configuration to the remote WTRU. The configuration may include an indication to the remote WTRU to enable measurements, an indication to the remote WTRU to transmit measurements, criteria that may be used by the remote WTRU to determine when a measurement report may be triggered from a transmission to the eNB, and / or an allowable list of mobile repeaters that may be measured.

[0100] For example, the configuration may be broadcast by the mobile repeater WTRU to some or all remote WTRUs connected to the mobile repeater WTRU. The broadcasting mechanism discussed herein may be used. The remote WTRU's configuration may be derived from the same or different measurement configuration of the mobile repeater WTRU. The mobile repeater WTRU's configuration may be sent to the mobile repeater WTRU by the eNB over a Uu link. For example, the mobile repeater WTRU's configuration may be sent using system information block (SIB) signaling or RRC signaling.

[0101] Based on the configuration, the remote WTRU may enable measurements over a PC5 link of mobile repeaters WTRUs that are transmitting discovery messages within communication range of the remote WTRU. An acceptable list of mobile repeaters that may be measured may be sent by the eNB to the remote WTRU. An acceptable list of mobile repeaters that may be measured may be sent by the eNB to the remote WTRU as part of the configuration. An acceptable list of mobile repeaters to which the remote WTRU is allowed to reselect may be sent by the eNB to the remote WTRU as part of the configuration.

[0102] The remote WTRU may receive a configuration indicating that the remote WTRU may send measurements to the eNB via the mobile repeater WTRU and may use an indication in the measurement report that indicates to the mobile repeater WTRU that the measurements are for the eNB. The remote WTRU may compile a list of measurements and send the list of measurements to the mobile repeater WTRU with an indication that the measurements are for the eNB. The indications and measurements may include a list of one or more mobile repeater WTRUs, signal quality of one or more mobile repeater WTRUs, and / or quality measurements of some or all of the mobile repeater WTRUs that are reported. The indications and measurements may be sent using the MAC CE over PC5.

[0103] The configuration may include criteria that may be used by the remote WTRU to determine when a measurement report may be triggered from a transmission to the eNB. The WTRU may trigger a report to the eNB when one or more of the configured criteria are satisfied and one or more of the criteria described herein as part of WTRU autonomous reselection are satisfied. An exemplary criterion for triggering a measurement report to the eNB may include information that a signal quality of a mobile repeater to which the remote WTRU is connected may be below a threshold for a given period of time. An exemplary criterion for triggering a measurement report to the eNB may include information that a mobile repeater to which the remote WTRU was connected may no longer be detected. An exemplary criterion for triggering a measurement report to the eNB may include information that a different candidate mobile repeater WTRU may be detected. The WTRU may trigger a report to the eNB when one or more of the configured criteria are satisfied and one or more of the criteria described herein as part of WTRU autonomous reselection are satisfied.

[0104] For example, a different candidate Mobile Repeater WTRU may be detected when the candidate Mobile Repeater WTRU satisfies higher layer configured connection criteria. The remote WTRU may select a candidate Mobile Repeater when the signal quality of the different candidate Mobile Repeater WTRU is likely to exceed a threshold during a time period. The remote WTRU may select a candidate Mobile Repeater when the signal quality of the different candidate Mobile Repeater WTRU is likely to be better than the Mobile Repeater to which the remote WTRU was connected by a threshold during a time period.

[0105] The mobile repeater WTRU may send measurements to the eNB over the Uu interface. For example, the mobile repeater WTRU may send measurements to the eNB over the Uu interface when it receives a measurement packet (e.g., a MAC CE or an RRC-like message) from the remote WTRU over the PC5 interface. This measurement report may be sent using RRC signaling and / or MAC CE. The measurement report may include an identity of the remote WTRU making the measurement. The identity may include an L2 ID, a physical layer ID, and / or the like. The measurement report may include a list of measured mobile repeater WTRUs. The list of measured mobile repeater WTRUs may be reported in terms of an L2 ID or a physical layer ID. The measurement report may include associated measurements of the mobile repeaters. The measurement report may include a measured quality of the mobile repeater to which the remote WTRU is connected. The measurement report may include a type of service requested by the WTRU.

[0106] The list of mobile repeaters WTRUs that the remote WTRU can report to the eNB may be filtered at the application layer based on the application layer services of the application layer information sent in the discovery message. A mobile repeater may or may not serve the remote WTRU's purposes. When a mobile repeater does not serve the remote WTRU's purposes, the remote WTRU may or may not send measurements related to the mobile repeater to the eNB. A mobile repeater may or may not provide service. When a mobile repeater does not provide service, the remote WTRU may or may not send measurements related to the mobile repeater to the eNB. A mobile repeater may be on a disallowed or unauthorized PLMN. When a mobile repeater is on a disallowed or unauthorized PLMN, the remote WTRU may or may not send measurements related to the mobile repeater to the eNB. The eNB may control reselection based on the list of mobile repeaters that can serve the remote WTRU.

[0107] The remote WTRU may receive a command to perform reselection to a mobile repeater that is measured and reported to the eNB. The remote WTRU may receive a command to perform reselection to a mobile repeater that is measured and reported to the eNB during a mobile repeater selection / reselection procedure. The eNB may send information to the mobile repeater WTRU using an RRC message. The mobile repeater WTRU may send an RRC message to the remote WTRU over a PC5 interface. The RRC message sent from the mobile repeater WTRU to the remote WTRU may be similar to the RRC message sent from the eNB to the mobile repeater WTRU. The MAC CE may be used to forward the reselection command.

[0108] Upon deciding to reselect the candidate Mobile Repeater, the remote WTRU may perform one or more of certain actions. Upon deciding to reselect the candidate Mobile Repeater, the remote WTRU may release a connection with the Mobile Repeater to which the remote WTRU is connected. Upon deciding to reselect the candidate Mobile Repeater, the remote WTRU may initiate a connection establishment to the reselected candidate Mobile Repeater. Upon deciding to reselect the candidate Mobile Repeater, the remote WTRU may maintain a connection to the Mobile Repeater to which the remote WTRU is connected and attempt to establish a connection to the reselected candidate Mobile Repeater. The remote WTRU may release a connection to the Mobile Repeater to which the remote WTRU is connected when it has successfully established a connection to the reselected candidate Mobile Repeater. The connection to the Mobile Repeater to which the remote WTRU is connected may be released after the remote WTRU has verified that the remote WTRU has started receiving a service from the reselected candidate Mobile Repeater. For example, the service may be eMBMS.

[0109] Mobile repeater selection / reselection may be triggered by one or more combinations of autonomous and / or eNB triggers. A configuration received by the remote WTRU may control the reselection behavior of the remote WTRU. The behavior of the remote WTRU may depend on the measured signal strength of the mobile repeater with which the remote WTRU is communicating. How the reselection is performed may depend on the measured signal strength of the mobile repeater with which the remote WTRU is communicating. This may allow the remote WTRU to have the flexibility to perform mobile repeater reselection on its own when the quality of the PC5 link and / or Uu link is degraded. The remote WTRU may or may not be able to successfully transmit measurements to the mobile repeater. The remote WTRU may be able to successfully transmit measurements to the eNB.

[0110] The combination of autonomous and eNB triggers may be controlled by certain rules related to Uu link quality. The combination of autonomous and eNB triggers may be controlled by certain rules related to link conditions between a remote WTRU and an eNB when the WTRU performs mobile repeater selection / reselection within the coverage of the eNB.

[0111] If certain quality criteria of the Uu link between the eNB and the mobile repeater WTRU are satisfied, the remote WTRU may or may not perform mobile repeater selection / reselection. For example, the remote WTRU may hold or delay selection / reselection when under eNB coverage. The remote WTRU may wait to receive a selection of the mobile repeater WTRU from the eNB. If the quality criteria of the Uu link are no longer satisfied, the remote WTRU may autonomously trigger selection / reselection on its own. If the quality criteria of the Uu link are no longer satisfied, the remote WTRU may autonomously select the mobile repeater WTRU for connection. For example, the determination that the quality of the Uu link is low enough to merit autonomous selection / reselection may be related to the measured RSRP of the eNB. The determination that the quality of the Uu link is low enough to merit autonomous selection / reselection may be related to measurements made by the WTRU on the Uu link being below a set threshold for a set time period. The determination that the quality of the Uu link is low enough to merit autonomous selection / reselection may be based on the state of the RRC connection on the Uu link, for example, the state of the RRC connection on the Uu link following a Radio Link Failure (RLF) and / or the state of the RRC connection on the Uu link following an unsuccessful RRC connection re-establishment may be used.

[0112] For example, the remote WTRU may receive two thresholds as part of the configuration (e.g., threshold 1>threshold 2). If the measurements of the mobile repeater WTRU to which the remote WTRU is connected are below threshold 1 but above threshold 2, the remote WTRU may be triggered to start making measurements of other mobile repeater WTRUs. The remote WTRU may be triggered to start sending these measurements to the eNB. The mechanisms discussed with respect to eNB triggered reselection may be used, for example, while the mobile repeater WTRU to which the remote WTRU is connected is below threshold 1 but still above threshold 2. If the measurements of the mobile repeater WTRU to which the remote WTRU is connected are below threshold 2, the mobile repeater WTRU may initiate a mobile repeater reselection procedure. For example, the mobile repeater reselection procedure may be as described with respect to remote WTRU autonomous reselection based on the mobile repeater signal quality falling below threshold 2. The WTRU may perform autonomous reselection and when the reselection decision criteria are triggered, the WTRU may inform the eNB of the reselection decision.

[0113] When reselecting a mobile repeater, the WTRU may autonomously initiate a connection establishment procedure to the reselected candidate mobile repeater. In one example, the remote WTRU may wait for an explicit indication from the eNB, e.g., the explicit indication may inform the remote WTRU whether to initiate a connection establishment to the reselected mobile repeater WTRU. The eNB may proactively stop establishing a connection to the reselected mobile repeater. Upon reselection to a mobile repeater, the WTRU may indicate to the reselected mobile repeater the identity of the mobile repeater to which the remote WTRU is connected. Indicating to the reselected mobile repeater the identity of the mobile repeater to which the remote WTRU is connected may occur within the establishment request or via a new PC5 message.

[0114] Internal states or conditions within the WTRU, the eNB, and / or a combination of the two may affect how reselection is performed. For example, if the remote WTRU starts in coverage and moves out of the coverage of the eNB, how reselection is performed when the remote WTRU is RRC_CONNECTED may differ from when the WTRU is RRC_IDLE. For example, in the RRC_CONNECTED state, reselection may be controlled by the eNB. The eNB may be permitted to make decisions regarding which mobile repeater the WTRU may be connected to. The remote WTRU may use transmission resources when the remote WTRU is connected to a mobile repeater. The remote WTRU was previously actively transmitting with the eNB in ​​connected mode. When the remote WTRU is RRC_IDLE, the remote WTRU may perform WTRU autonomous mobile repeater selection. The remote WTRU may potentially receive eMBMS traffic from the eNB. The remote WTRU may expect to receive eMBMS from the mobile repeater WTRU.

[0115] Lower layer measurements may be used to support the selection / reselection procedure. Upper layers may configure the lower layer measurements. Upper layers may enable measurements at different times or continuously for repeaters, including the repeater to which the remote WTRU is connected.

[0116] Enhancements to the R12 discovery / communication and measurement procedures may be introduced to provide a measured quality of the mobile repeater WTRU as seen by the remote WTRU. An indication of the quality of the mobile repeater WTRU from the remote WTRU may be provided. An indication of the quality of the mobile repeater WTRU from the remote WTRU may be provided to higher layers.

[0117] Measurement configuration of lower layers (e.g., PHY / MAC / RRC) may be done by upper layers. Upper layers may configure lower layers to report measurements associated with transport blocks originating from a source. A transport block may originate from a specific source or any number of sources identified as a mobile repeater. One or more sources may be identified as a source WTRU ID. One or more sources may be found in the MAC header of the SL-SCH. One or more sources may be found in the Layer 1 ID decoded in the SA. One or more sources may be found in an ID retrieved from the PSBCH. One or more sources may be received from resources reserved for sending messages or signals.

[0118] The measurements may be enabled by upper layers (e.g., upper layers) at different times. The measurements may be enabled during a time period when the upper layers are expecting a Model B response message and / or a Model A announcement message. The Model B response message and / or the Model A announcement message may be transmitted by a potential mobile repeater. The measurements may be disabled by upper layers in the remote WTRU. The measurements may be disabled by upper layers in the remote WTRU when some or all expected discovery messages are received. Some or all expected discovery messages may be received after expiration of a timer.

[0119] Measurements may be enabled continuously to allow for continuous mobile repeater WTRU measurements. Measurements may be enabled continuously on the mobile repeater to which the remote WTRU is connected. Measurements for other mobile repeaters may be started and / or stopped. Measurements may be enabled continuously based on the value of the measurements. For example, if the measurements for the mobile repeater to which the remote WTRU is connected fall below a certain threshold, the upper layers may enable measurements for other ranked and measured mobile repeaters. If the measurements for the mobile repeater to which the remote WTRU is connected fall below a certain threshold, the upper layers may perform measurements for some or all mobile repeaters sending announcements. The threshold may be configured by the upper layers in the remote WTRU or by the mobile repeater WTRU or eNB. The threshold may be sent from the mobile repeater WTRU or eNB to the remote WTRU during establishment of a secure link with the remote WTRU.

[0120] To support measurements of a mobile repeater WTRU, a PSBCH may be transmitted by the WTRU acting as a mobile repeater at a given time. The upper layers of the mobile repeater WTRU may enable transmission of the PSBCH whenever a mobile repeater connection is made to the mobile repeater and / or be disabled whenever the WTRU no longer has a mobile repeater connection to it.

[0121] The remote WTRU may perform measurements on a sidelink broadcast channel (SL-BCH) and / or a sidelink shared channel (SL-SCH).

[0122] The remote WTRU may perform measurements on a DMRS transmitted by a mobile repeater WTRU on the SL-SCH, for example, when a Model B discovery response or a Model A mobile repeater announcement is sent by the remote WTRU via D2D communication (e.g., on the SL-SCH).

[0123] The mobile repeater WTRU's measurements / quality may be based on measurements made by the remote WTRU of the DMRS transmitted in the PSBCH. To enable measurement procedures (e.g., measurements of the SL-SCH), the R12 PSBCH may be enhanced to include the L2 WTRU ID of the WTRU transmitting the PSBCH in the payload. To enable measurements during a Model B response or Model A announcement when the response is transmitted using D2D discovery, the D2D discovery may be enhanced to allow the PSBCH to be transmitted during D2D discovery. For example, the upper layers in the mobile repeater WTRU may configure the lower layers to transmit the PSBCH using D2D discovery to send the Model B response.

[0124] Radio access network level repeater control may comprise operations and procedures for pre-selecting a repeater and / or initiating a repeater at various stages including repeater discovery, repeater connection request, request to receive a broadcast from TMGI, and / or the like.

[0125] Mobile repeater operation may be controlled by an eNB. The eNB may perform resource allocation for mobile repeater operation. For example, the eNB may specify which resources must be used by a mobile repeater WTRU to communicate with a remote WTRU (e.g., and / or vice versa). The eNB may allow / reject mobile repeater operation depending on available resources, optimized resources, and WTRU-to-mobile repeater grouping. The eNB may interact with higher layers after certain procedures. For example, the mobile repeater may send requests and / or reports to the eNB.

[0126] To enable RAN control of mobile repeater operation, the mobile repeater WTRU may initiate the transmission of reports and / or requests to the eNB. The mobile repeater WTRU may send the request according to one or more of the following triggers: The trigger may include a pre-selection that occurs prior to a higher layer mobile repeater discovery operation. The trigger may include an initiation of a mobile repeater Model A discovery. The trigger may include an initiation of a mobile repeater Model B discovery when the mobile repeater is in a monitor mode. The trigger may include an initiation of a mobile repeater Model B discovery when the mobile repeater wants to initiate the transmission of a solicitation message. The trigger may include receipt of a solicitation message (e.g., from Model B) for which the WTRU is authorized to send a response message. The solicitation message may be from a Model B discovery. The trigger may include a request by a remote WTRU to establish a one-to-one connection. The trigger may include successful completion of a connection as determined by higher layers. The trigger may include a request by the remote WTRU to receive a broadcast message for a particular TMGI. The trigger may include detection of a TMGI from an eNB that the WTRU is requested to monitor the requested TMGI. The trigger may include a request by the remote WTRU to change the type of service. For example, the change of service may include initiating a different video call over the same mobile repeater link. The change of service may include tearing down an existing service. The change of service may include stopping the link to the service.

[0127] The request / report may include certain information. The request / report may include certain type of discovery. The type of discovery may be mobile repeater, group member, or the like. The request / report may include discovery model type. The discovery model type may be model A or model B. The type of discovery may include certain stage of model B. The state of model B may include monitoring for solicitation message, sending solicitation message, triggering received solicitation message and requested response, or the like. The request / report may include connection information. The connection information may be for helping the eNB determine if the eNB supports the service. The connection information may be for helping the eNB determine if the mobile repeater can act as a mobile repeater. The request / report may include a measurement report indicating signal strength for the eNB. The request / report may include an ID of the remote WTRU. The request / report may include an ID of the detected mobile repeater announcing mobile repeater operation or announcing a service. The request / report may include a TMGI requested by the WTRU. The request / report may include a TMGI that detects that a mobile repeater has requested monitoring. The request / report may include measurements of the selected mobile repeater and / or other mobile repeaters. The measurements may be made by the remote WTRU and / or the mobile repeater WTRU. The request / report may include an indication of services and / or resources required by the remote WTRU.

[0128] The request message may be a MOBILE RELAY_REQUEST_MESSAGE. Depending on which stage the request message is sent in, the response from the eNB may configure different behaviors in the WTRU. The MOBILE RELAY_REQUEST_MESSAGE may be sent to the eNB via RRC or MAC CE. The MOBILE RELAY_REQUEST_MESSAGE may trigger allocation by the eNB of resources to be used by the mobile relay. The MOBILE RELAY_REQUEST_MESSAGE may trigger a complete rejection of the request by the eNB.

[0129] The WTRU may be configured to act as a mobile repeater and / or to refuse mobile repeater-related operations before and / or after the initialization of mobile repeater-related procedures. Mobile repeater-related procedures may include discovery, connection establishment, TMGI request, and / or the like.

[0130] A WTRU may be configured to act as a mobile repeater during a pre-selection process based on the WTRU's capability to act as a mobile repeater, the number of remote WTRUs for which the WTRU may potentially serve as determined by a pre-discovery procedure, and / or the location of the WTRU. Pre-selection may occur before the WTRU receives a higher layer request for operation as a mobile repeater. The process of mobile repeater WTRU pre-selection may be performed to allow an in-coverage WTRU to be intelligently selected to act as a mobile repeater WTRU. By performing a pre-selection process, multiple WTRUs may be avoided from mobile communicating the same information when the information may be communicated by a mobile repeater WTRU. The pre-selection of a mobile repeater WTRU may be performed by an eNB and / or a network. The pre-selection of a mobile repeater WTRU may be performed by an eNB and a network acting in cooperation. A network, an application / function, or a combination of a network, an application / function may be used in the pre-selection (e.g., by an eNB).

[0131] The eNB may configure the WTRU to act as a mobile repeater based on the WTRU's capabilities. The WTRU may register with the eNB and provide its capabilities to the eNB and / or the network. The WTRU may provide information regarding whether it can operate as a mobile repeater. The WTRU may provide information regarding its mobile repeater properties. For example, the mobile repeater properties may include whether the WTRU can operate using one or more separate radios, separate operating frequencies / bands, and / or the like.

[0132] A pre-selection of a mobile repeater may be made based on the location of the mobile repeater. The eNB may configure the WTRU to operate as a mobile repeater and enable it to participate in mobile repeater discovery based on the location of the WTRU and / or the capability of the WTRU to act as a mobile repeater. FIG. 8 illustrates an example pre-selection based on location. The WTRU may connect to an eNB at 802 and / or send its mobile repeater capability information to the eNB. The capability information may include frequencies on which the WTRU can operate. The capability information may include capability to operate with separate radios. The capability information may include capability releasing support. For example, the capability releasing support may include whether the WTRU supports mobile repeater operation. The eNB may determine the location of the WTRU at 804. The eNB may use channel quality measurements. The eNB may use a specific capability for localization. The specific capability for localization may be obtained from higher layers.

[0133] The eNB may determine 806 whether to enable the WTRU to function as a mobile repeater. The eNB may use the eNB's knowledge of the WTRU's location relative to the eNB. For example, the eNB may determine 806 to configure the WTRU as a mobile repeater if the WTRU is close to the coverage edge of the eNB. A WTRU close to the coverage edge of the eNB may serve the largest number of potential remote WTRUs that are outside the coverage area of ​​the eNB. A WTRU that is known by the eNB to be relatively close to the eNB may or may not be configured by the eNB as a mobile repeater at 806. For example, a WTRU that is known by the eNB to be relatively close to the eNB may not be configured by the eNB as a mobile repeater if other options exist. Other options may include a mobile repeater WTRU that is at the edge of the coverage area of ​​the eNB. The eNB may or may not advertise a WTRU that is known by the eNB to be relatively close to the eNB to the WTRU searching for a mobile repeater. The pre-selection process may end.

[0134] The eNB may send a message to the WTRU to configure the WTRU to participate in mobile repeater discovery or to disable mobile repeater discovery, at 808. If the WTRU is enabled to operate as a mobile repeater, the eNB may assign discovery or communication resources to the mobile repeater. The eNB may send an RRC message to configure / reconfigure the mobile repeater D2D resources. For example, the eNB may configure higher layers in the mobile repeater to listen for request messages and / or send Model A announcement messages. The WTRU may receive a positive indication of acting as a mobile repeater. The WTRU may indicate to higher layers that it can accept mobile repeater solicitation messages. The WTRU may start transmitting Model A discovery announcement messages, at 810. The WTRU may receive a negative indication. The negative indication may indicate that the WTRU cannot act as a mobile repeater. The WTRU may trigger a notification to the upper layers. The notification may inform upper layers not to send Model A announcements or not to respond to Model B solicitation messages. The eNB may or may not configure discovery resources for the WTRU if the WTRU is not capable of acting as a mobile repeater.

[0135] If mobile repeater operation is accepted, the eNB and / or mobile repeater may initiate a reconfiguration of mobile repeater resources at 808. The resources may be used for discovery at 810. Discovery may include Model A discovery and / or Model B discovery. For example, for Model A discovery, the mobile repeater WTRU may send a discovery announcement for mobile repeater discovery. The WTRU may request additional mobile repeater resources based on the results of repeater initiation during repeater discovery and / or during a request to receive a broadcast from the TMGI.

[0136] The location-based pre-selection may be performed via signaling. The eNB may use the signaling to provide the WTRU with acceptable locations for mobile repeater operation. The signaling may include broadcast signaling or dedicated RRC signaling. For example, the eNB may signal the permissible locations for mobile repeater operation via broadcast signaling. The WTRU may perform its own determination of whether the WTRU's location may be within acceptable locations for mobile repeater operation. The WTRU may perform its own determination of whether the WTRU's location may satisfy the eNB's location requirements and / or whether the WTRU's location may satisfy other requirements. If the WTRU determines that the WTRU's location satisfies the eNB's location requirements and other requirements, the WTRU may operate as a mobile repeater. The WTRU may utilize resources allocated by the eNB to perform discovery. The eNB may have been assigned resources via dedicated signaling and / or broadcast signaling.

[0137] The pre-selection of mobile repeaters may be based on pre-discovery of WTRUs that can serve as remote WTRUs. An eNB / network / function may initiate a pre-discovery procedure to determine which WTRUs can be configured as mobile repeaters for which potential remote WTRUs. The pre-discovery procedure may use R12 D2D discovery to determine which WTRUs are in close proximity to each other. The pre-discovery procedure may use R12 D2D discovery to determine which WTRUs are capable of mobile repeater operation. The pre-discovery procedure may use R12 D2D discovery to determine which WTRUs can serve the maximum number of remote WTRUs.

[0138] For example, an eNB may perform a pre-discovery procedure. An eNB may perform the pre-discovery procedure periodically. An eNB may use the pre-discovery procedure eNB to identify potential mobile repeater WTRUs in the eNB coverage. An eNB may initiate this procedure when multiple WTRUs are already operating as mobile repeaters. An eNB may use the pre-discovery procedure eNB to cause a mobile repeater WTRU to stop operating as a mobile repeater WTRU.

[0139] The pre-discovery procedure may comprise one or more of the following steps in any order: In the pre-discovery procedure, an eNB may configure some or all D2D-capable WTRUs in its coverage that have registered with the network to listen for discovery messages on a pre-configured discovery resource pool. In the pre-discovery procedure, a remote WTRU may perform a self-initiated discovery message to find a D2D WTRU that can act as a mobile repeater. The remote WTRU may perform a self-initiated discovery message when it is powered on without eNB coverage. The remote WTRU may perform a self-initiated discovery message when it moves to an out-of-coverage scenario. The code of the self-initiated discovery message may be hard-coded or otherwise pre-configured in the WTRU. A default value may be used for the mobile repeater search. The discovery message may include a "mobile repeater search" code. The discovery message may include an identifier of the WTRU. The WTRU identifier may be used to identify which WTRU is sending the discovery message. The WTRU identifier may be used to identify which WTRU is searching for the mobile repeater. The identifier may be part of the application code in the discovery message. Remote WTRUs out of coverage of an eNB may use pre-configured discovery resources as defined in R12. Out-of-coverage WTRUs already served by a mobile repeater may or may not send discovery messages.

[0140] In a pre-discovery procedure, some or all D2D WTRUs that successfully receive a discovery message with application code "Mobile Repeater Search" may report the receipt of the discovery message to the eNB / network. The reporting may be performed via an RRC message, a MAC CE, and / or an application message. The report may include the identity of the remote WTRU. The D2D-enabled WTRU may be responsible for sending the report. The D2D-enabled WTRU may compile a report including some or all WTRUs for which it has received a discovery message with code "Mobile Repeater Search" during a certain period of time.

[0141] In the pre-discovery procedure, an eNB may collect some or all reports from various D2D-enabled WTRUs in its coverage. The eNB may designate a set of WTRUs in its coverage to act as mobile repeaters. The eNB may designate a set of WTRUs based on the reported remote WTRUs. The eNB may designate a set of WTRUs based on which WTRUs in its coverage have reported remote WTRUs multiple times. In the pre-discovery procedure, an eNB may indicate to the core network that a WTRU or set of WTRUs may be configured as a WTRU-network mobile repeater. In the pre-discovery procedure, a selected coverage WTRU may be configured as a mobile repeater. The selected mobile repeater WTRU may perform a mobile repeater discovery operation. The mobile repeater discovery operation may be based on Model A and / or Model B.

[0142] The WTRU may be configured to act as a mobile repeater and / or reject mobile repeater-related operations after initialization of mobile repeater-related procedures. Mobile repeater initiation may occur at various stages. Mobile repeater initiation may occur during mobile repeater discovery. If the eNB and WTRU support mobile repeater operation, higher layers associated with the WTRU may initiate mobile repeater-related procedures. The WTRU may trigger a report or request to the eNB. Mobile repeater-related procedures may include Model A, Model B, mobile repeater announcement, successful establishment from WTRU to mobile repeater, TMGI request, and / or the like.

[0143] The WTRU may trigger a report to the eNB when a Model A discovery procedure is triggered by higher layers in the WTRU. The WTRU may trigger a report to the eNB when a Model B solicitation request is received and the mobile repeater WTRU may send a response. The response may be sent according to higher layers.

[0144] Certain information may be provided to the eNB. The report may include information. The information may include a discovery type. The discovery type may include mobile repeater discovery (e.g., WTRU-to-network discovery), group member discovery, or WTRU-to-WTRU mobile repeater discovery. The information may include a type of message. The type of message may include announcement, request, and / or response. The information may include connection information. The connection information may include what the mobile repeater WTRU intends to announce. The connection information may include what the mobile repeater WTRU intends to send in the response message. The information may include a received WTRU ID and / or a group of received WTRU IDs in the request message if the discovery is a Model B response type. The information may include a WTRU ID or a mobile repeater ID of the WTRU sending the report to the eNB. The information may include a channel quality measurement of the WTRU sending the message or location information of the WTRU sending the message. The channel quality measurements may be for an eNB, for a detected mobile repeater WTRU, and / or for a remote WTRU.

[0145] The eNB may take certain actions: The eNB may receive a request (e.g., a request for a mobile repeater WTRU). The eNB may decide whether to allocate resources to a potential candidate mobile repeater WTRU for the requested service. The eNB may decide whether to allow the WTRU to operate as a mobile repeater. To allow the WTRU to operate as a mobile repeater, the eNB may enable initiation of transmission of discovery messages, announcements, and / or WTRU responses.

[0146] The eNB may determine whether to allow a potential candidate WTRU to operate as a mobile repeater based on a report sent by the WTRU. The eNB may determine whether to allow a potential candidate WTRU to operate as a mobile repeater based on certain information. The eNB may determine whether to allow a potential candidate WTRU to operate as a mobile repeater based on a number of reported remote WTRUs and / or request requests and / or reported mobile repeater WTRUs indicating mobile repeater establishment from remote WTRUs. The eNB may determine whether to allow a potential candidate WTRU to operate as a mobile repeater based on a service type requested by a remote WTRU or a mobile repeater WTRU if the network supports the service. The eNB may determine whether to allow a potential candidate WTRU to operate as a mobile repeater based on a location of the WTRU with respect to the eNB. The location of the WTRU with respect to the eNB may be determined based on received measurements. The eNB may determine whether to allow a potential candidate WTRU to operate as a mobile repeater based on a candidate mobile repeater WTRU detected in the vicinity of a potential candidate mobile repeater WTRU requesting to become a mobile repeater. Based on the report and information sent by the WTRU, the eNB can decide whether to allow mobile repeater operation and can respond to the potential candidate WTRU by allocating resources if the resources are not already available in the WTRU. The eNB can send an explicit message indicating that mobile repeater operation is allowed.

[0147] A potential candidate mobile repeater WTRU may take certain actions. The WTRU may initiate transmission of higher layer messages and / or reconfiguration of mobile repeater resources when the potential candidate mobile repeater WTRU receives a message providing resources for a requested service. The WTRU may initiate transmission of higher layer messages and / or reconfiguration of mobile repeater resources when the potential candidate mobile repeater WTRU receives an explicit approval for mobile repeater operation. The WTRU may initiate transmission of higher layer messages and / or reconfiguration of mobile repeater resources when the WTRU determines that the criteria for becoming a mobile repeater are satisfied. The criteria may be configured by the eNB. A mobile repeater operation discovery transmission may be rejected. When a mobile repeater operation discovery transmission may be rejected, the higher layers may stop discovery message transmission.

[0148] Mobile repeater initiation may occur during a mobile repeater connection request. The mobile repeater WTRU may send a report to the eNB when a connection with a remote WTRU is requested to be established. The mobile repeater WTRU may send a report to the eNB when a connection with a remote WTRU is established.

[0149] Mobile repeater initiation may occur during a mobile repeater connection request. The mobile repeater WTRU may be triggered to report and / or send a request to the network when certain events occur. The triggering event may be that the mobile repeater WTRU has established a successful connection with a remote WTRU. The upper layers may determine if the mobile repeater WTRU has established a successful connection with a remote WTRU. The successful connection may be established with additional remote WTRUs. The triggering event may be that the mobile repeater WTRU has established a successful connection with an additional remote WTRU. The triggering event may be that the mobile repeater WTRU has established a successful connection with a remote WTRU that belongs to a group different from the group of the remote WTRU. The triggering event may be that the mobile repeater WTRU has established a successful connection with a remote WTRU that may request a different type of service than the service requested by the remote WTRU. The triggering event may be that the mobile repeater WTRU receives a connection establishment message from an additional remote WTRU. The triggering event may be that the remote WTRU requests an additional or different service. The triggering event may be the remote WTRU disconnecting from the mobile repeater WTRU. The triggering event may be that the TMGI request is not refreshed by the remote WTRU, indicating that the remote WTRU may or may not use the services of the mobile repeater.

[0150] The report may comprise an identity of the remote or potential remote WTRU and / or service related information. The report may be the same report sent when a triggering event occurs. The information in the report may include a remote WTRU identity (e.g., WTRU ID), a list of WTRUs to which the remote WTRU is connected, and / or a WTRU ID of a remote WTRU that is requesting or has requested connection establishment. The information in the report may include a service or any other service related information. The service information may include connection information and / or group information. The service related information may include connection information. The connection may be for requesting a list of available TMGIs. For example, the connection may be for requesting a connection to a broadcast service. The connection may be for one-to-one communication. The one-to-one communication may include a file download from a server. The information in the report may include measurements on the eNB.

[0151] The eNB may accept or reject the request and / or report to connect, and / or the eNB may initiate a redirection process as described herein. The eNB may decide not to provide resources for the mobile repeater communication, reject the connection to the remote WTRU, or redirect it. The decision may be based on information received by the eNB. The received information may include services provided, requested TMGI, measurements, and / or methods described herein. The mobile repeater initiation may be rejected by the eNB for various reasons. For example, the eNB may not be able to provide communication resources used for the mobile repeater connection (e.g., even if the mobile repeater WTRU could be configured with discovery resources). There may be other mobile repeaters in the system that can provide services for the remote WTRU.

[0152] The mobile repeater WTRU may forward the rejection to higher layers. Receipt of the rejection by higher layers may trigger the higher layers to initiate procedures to release and / or reject the connection with the remote WTRU. For example, the mobile repeater WTRU may reject the connection by not continuing the connection establishment procedure with higher layers and / or by sending a connection establishment failure message to the remote WTRU. The report provided herein may be sent to the eNB before the connection between the mobile repeater WTRU and the remote WTRU is fully authorized by the function. For example, the report provided herein may be sent to the eNB when a connection establishment procedure is initiated from the remote WTRU to the mobile repeater WTRU. Forwarding the rejection to higher layers may initiate a release or stop of the connection between the remote WTRU and the mobile repeater WTRU so that the remote WTRU can find another candidate mobile repeater WTRU.

[0153] Mobile repeater initiation may occur during a request to receive a broadcast from a TMGI. The eNB may reject a request originating from a remote WTRU to receive an eMBMS broadcast from a mobile repeater. The eNB may reject a mobile repeater initiation or a remote WTRU connection to a mobile repeater during a request to receive a broadcast from a TMGI for various reasons. For example, the eNB may or may not be able to provide the mobile repeater with sufficient resources to broadcast traffic for the associated TMGI. The eNB may reject a mobile repeater initiation to a remote WTRU connection so that the remote WTRU can connect to another mobile repeater that may be broadcasting the requested TMGI. The eNB may or may not have resources to allocate to the mobile repeater WTRU. The mobile repeater WTRU may be acting as a mobile repeater for other remote WTRUs.

[0154] Potential rejection of a mobile repeater connection by an eNB during a request to receive a broadcast from a TMGI may be augmented by identifying one or more alternative mobile repeater WTRUs to which a remote WTRU may connect to obtain service. Identifying one or more alternative mobile repeater WTRUs to which a remote WTRU may connect to obtain service may enable an eNB to control which mobile repeater WTRUs may forward broadcast services related to a particular TMGI. Being able to control which mobile repeater WTRUs may forward broadcast services related to a particular TMGI may avoid scenarios where different mobile repeater WTRUs may be sending broadcast services associated with the same TMGI to different remote WTRUs. Services associated with the same TMGI may be broadcast by a mobile repeater WTRU to different remote WTRUs. Multiple remote WTRUs may be connected to the same mobile repeater WTRU.

[0155] The eMBMS broadcast sent by the mobile repeater WTRU may be controlled by the eNB via sending a request. For example, the request may be a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE from the mobile repeater WTRU to the eNB. The upper layers may trigger the lower layers in the mobile repeater WTRU to send a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB in ​​one or more of the following scenarios: The upper layers may trigger the lower layers in the mobile repeater WTRU to send a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB when the upper layers in the mobile repeater WTRU receive a request from a remote WTRU to monitor a particular TMGI. The upper layers may trigger the lower layers of the mobile repeater WTRU to send a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB when the upper layers of the mobile repeater WTRU detect that the remote WTRU stops monitoring a particular TMGI that the remote WTRU has requested. The upper layers of the mobile repeater WTRU may receive a direct message sent from the remote WTRU to the mobile repeater WTRU. The direct message may indicate that the upper layers of the mobile repeater WTRU may stop monitoring a particular TMGI that the remote WTRU has requested. The upper layers of the mobile repeater WTRU may detect that the remote WTRU stops re-requesting the same TMGI after a predefined period of time. The upper layers may trigger the lower layers of the mobile repeater WTRU to send a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB when the upper layers of the mobile repeater WTRU receive a request from the remote WTRU to monitor a TMGI that does not correspond to a TMGI monitored by the mobile repeater WTRU. For example, a TMGI that does not correspond to a TMGI monitored by the mobile repeater WTRU may include a new TMGI.Some or all broadcast messages associated with the TMGI may be sent by the mobile repeater via PC5 using the same D2D resource. The upper layers may trigger the lower layers in the mobile repeater WTRU to send a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB when the mobile repeater WTRU stops monitoring the TMGI for the WTRU. The upper layers may trigger the lower layers in the mobile repeater WTRU to send a BROADCAST_MOBILE RELAY_REQUEST_MESSAGE to the eNB when the mobile repeater WTRU may periodically send a BROADCAST_MOBILE RELAY_REQUEST message to the eNB with the requested information.

[0156] The BROADCAST_MOBILE RELAY_REQUEST message may include certain information. The BROADCAST_MOBILE RELAY_REQUEST message may include an indication of the cause for sending the BROADCAST_MOBILE RELAY_REQUEST message. Exemplary causes may include a new WTRU requesting that the TMGI be monitored, a WTRU that no longer monitors the TMGI, periodic reporting, or the like. The BROADCAST_MOBILE RELAY_REQUEST message may include the TMGI that is requested to be monitored and communicated. The BROADCAST_MOBILE RELAY_REQUEST message may include a WTRU ID of the remote WTRU that is requesting the TMGI and / or a WTRU ID of the remote WTRU that has stopped requesting receipt of the TMGI. The WTRU ID may be an L2 WTRU ID, a physical layer ID of the WTRU, or the like. The BROADCAST_MOBILE RELAY_REQUEST message may include connection information associated with a connection that the remote WTRU has established with the mobile repeater WTRU. The BROADCAST_MOBILE RELAY_REQUEST message may include service related information. The service related information may identify the amount of resources that may be used to forward broadcast traffic over PC5. The BROADCAST_MOBILE RELAY_REQUEST message may include information described herein including TMGI, WTRU ID, connection information, additional service information of remote WTRUs listening to the mobile repeater ID for eMBMS broadcasts. The BROADCAST_MOBILE RELAY_REQUEST message may include measurements from the remote WTRU of other mobile repeater WTRUs detected in the vicinity that may provide service. The BROADCAST_MOBILE RELAY_REQUEST message may include an indication of the presence of other mobile repeater WTRUs detected in the vicinity that may provide service.

[0157] The BROADCAST_MOBILE RELAY_REQUEST message may be sent using, for example, a MAC CE or RRC message. The BROADCAST_MOBILE RELAY_REQUEST message is used as an example. Messages described herein may be used to send such a request and / or information included in the BROADCAST_MOBILE RELAY_REQUEST message. A WTRU INFORMATION message may be used to send such a request and / or information included in the BROADCAST_MOBILE RELAY_REQUEST message. The request and / or information may be one of more of the information described herein.

[0158] The eNB may not respond to the BROADCAST_MOBILE RELAY_REQUEST message. For example, the eNB may not respond to the BROADCAST_MOBILE RELAY_REQUEST message when a periodic BROADCAST_MOBILE RELAY_REQUEST message provides an indication.

[0159] The eNB may respond to the BROADCAST_MOBILE RELAY_REQUEST message in various ways. The eNB may reconfigure the D2D resources requested by the mobile relay. The eNB may respond to the BROADCAST_MOBILE RELAY_REQUEST via an RRC message, MAC CE, or the like. The response may be forwarded by the mobile relay WTRU to its upper layers.

[0160] The eNB response may include an acceptance of the request. For example, the eNB acceptance may cause upper layers in the remote WTRU to respond to the request. For example, if the request was sent as a result of the remote WTRU requesting to monitor TMGI, the acceptance may cause upper layers in the remote WTRU to accept the TMGI monitoring request from the remote WTRU and provide information associated with the TMGI monitoring request.

[0161] The eNB's response may include rejection of the request. For example, the eNB may reject the mobile repeater WTRU's request to monitor or the mobile repeater per TMGI. The mobile repeater WTRU may forward the rejection to higher layers. The higher layers may trigger the mobile repeater WTRU to send a rejection message to the remote WTRU. The rejection message may indicate the rejection of the mobile repeater WTRU to the mobile relaying for the TMGI. The connection between the remote WTRU and the mobile repeater WTRU may be broken. A disconnection may be initiated upon receipt of the rejection message by the remote WTRU. The remote WTRU may find a different candidate mobile repeater WTRU.

[0162] The eNB's response may include sending to the mobile repeater WTRU, along with a rejection of the request, an identification of one or more mobile repeaters WTRUs (e.g., L2 IDs of the mobile repeaters) that provide connectivity to services that the rejected mobile repeater WTRU can provide. The identification may be sent to upper layers. The upper layers may provide a redirection message. The redirection message may prompt the remote WTRU to behave in various ways. In some examples, the redirection message may suggest to the remote WTRU to behave in a certain way. In some examples, the redirection message may force the remote WTRU to behave in a certain way.

[0163] The redirection message may prompt the remote WTRU to disconnect from the mobile repeater to which the remote WTRU is connected, which may not be tasked with communicating broadcast traffic associated with the requested TMGI.

[0164] The redirection message may prompt the remote WTRU to initiate a mobile repeater reselection process to find a candidate mobile repeater that can provide the services that the rejected mobile repeater WTRU can provide.

[0165] The redirection message may prompt the remote WTRU to initiate a connection with a candidate Mobile Repeater WTRU that may be included in the redirection message. The remote WTRU may ignore the prompt or act accordingly. For example, the remote WTRU may not listen to the candidate Mobile Repeater proposed by the eNB. In one example, the candidate Mobile Repeater may not have responded to Model B discovery when the remote WTRU initiates Model B discovery. The remote WTRU may ignore the candidate Mobile Repeater's proposal and continue to influence the Mobile Repeater to which the remote WTRU is connected.

[0166] The remote WTRU may act accordingly when the redirection message prompts the remote WTRU to initiate a connection with the candidate Mobile Repeater WTRU. The remote WTRU may listen to the candidate Mobile Repeater proposed by the eNB. In one example, the candidate Mobile Repeater may have responded to the Model B discovery when the remote WTRU initiates the Model B discovery. The remote WTRU may disconnect from the Mobile Repeater to which the remote WTRU is connected. The remote WTRU may initiate a connection with the candidate Mobile Repeater proposed by the eNB. The remote WTRU may request the broadcast of a TMGI. It may be possible that the candidate Mobile Repeater is already broadcasting the same TMGI.

[0167] 9 is an example of selection / connection establishment. A remote WTRU 920 and a mobile repeater WTRU 922 may engage in discovery (e.g., public safety discovery or commercial communication discovery) at 902. The mobile repeater WTRU 922 may have been previously initiated by the eNB 924 using criteria described herein. The remote WTRU 920 may perform measurements of nearby potential candidate mobile repeaters at 902. The remote WTRU 920 may use signals in a discovery message sent by the mobile repeater WTRU 922. The remote WTRU 920 may select a mobile repeater WTRU that has acceptable measurements and whose upper layer information (e.g., service, PLMN ID) satisfies the service requirements of the remote WTRU 920. The remote WTRU 920 may send a one-to-one connection request to the mobile repeater WTRU 922 at 904. The one-to-one connection request may include identities and measurements of the selected and other mobile repeaters, requested services, and / or the like. The remote WTRU 920 may send 904 an identity of the mobile repeater WTRU 922 and identities of the candidate mobile repeaters. The remote WTRU 920 may send 904 a service requirement. The remote WTRU 920 may send 904 a list of mobile repeaters WTRUs and measured qualities of mobile repeaters WTRUs that can satisfy the requirements of the remote WTRU 920. The mobile repeater WTRU 922 may send 906 a mobile repeat request to the eNB 924. The request may include identities and measurements of the selected and other mobile repeaters, requested services, and / or the like. The mobile relay request may include an identity of the mobile repeater WTRU 922 and identities of candidate mobile repeaters, a list of mobile repeaters WTRUs and measured qualities of the mobile repeaters WTRUs that can satisfy the requirements of the remote WTRU 920, and / or service requirements of the remote WTRU 920. The mobile relay request may include the number of WTRUs connected to the mobile repeater WTRU 922.The mobile repeater WTRU 922 may forward the measurements sent by the remote WTRU 920 to the eNB 924 at 906. At 908, the eNB 924 may respond to the request forwarded at 906. The eNB 924 may accept the request at 908, reject the request, and / or provide candidate mobile repeaters from the list of mobile repeaters provided at 906 and given by the remote WTRU 920. The eNB 924 may reconfigure D2D resources at 908. For example, the eNB 924 may reconfigure D2D resources at 908 if additional resources must be allocated to support a transmission. Secure link establishment may occur at 910. The remote WTRU 920 may indicate a request to change service to the mobile repeater WTRU 922 at 912 while connected with the mobile repeater WTRU 922. The change in service at 912 may be based on additional bearers established to the network, initiation of additional / different video connections, ceasing use of the mobile repeater WTRU 922 or other mobile repeaters, and / or the like. The mobile repeater WTRU 922 may send a different mobile relay request at 914 indicating the change in service for the remote WTRU 920. The different mobile relay request at 914 may include an identification of the mobile repeater WTRU 922, an identification of candidate mobile repeaters that may be selected, and an identification of the candidate mobile repeaters. The different mobile relay request at 914 may include a list of mobile repeaters WTRUs that can satisfy the change in service requirements of the remote WTRU 920 and a measured quality of the mobile repeaters WTRUs in the list, and / or the service requirements of the remote WTRU 920. The mobile relay request may include the number of WTRUs connected to the mobile repeater WTRU 922 and / or the candidate mobile repeaters that may be selected at 914. At 916, the eNB 924 may respond to the request sent at 914. The eNB 924 can accept the request, reject the request, or provide a candidate mobile repeater from the list of mobile repeaters provided at 914 .The eNB 924 may reconfigure the D2D resources at 916. A response by the eNB 924 may trigger a release of the link to the mobile repeater WTRU 922 at 918. A response by the eNB 924 may trigger a reconfiguration of the resources used on the PC5 interface at 918.

[0168] Resources may be allocated or assigned for the mobile repeater WTRU and / or D2D communications. Resource allocation, including resource scheduling, may be performed by an eNB or a mobile repeater. Resource allocation to the mobile repeater WTRU may be performed based on various requirements including an estimate of services that may be provided to the remote WTRU. Resource allocation for D2D communications, including resource scheduling, may be achieved by various approaches. Some approaches may include an eNB configuring a resource pool and a WTRU scheduling resources in the resource pool. Some approaches may include an eNB configuring a resource pool and a WTRU separating resources and allocating the separated resources to a remote WTRU or a group of remote WTRUs. Some approaches may include an eNB directly scheduling resources in the resource pool. For example, an eNB may directly schedule the resource pool for the mobile repeater WTRU and the WTRU may schedule resources in the resource pool for other WTRUs.

[0169] A mobile repeater WTRU may be configured with a pool of resources. For example, an eNB may allocate a set of resources or a resource pool to be used for a mobile repeater. The pool of resources may be dedicated to the mobile repeater. The dedicated mobile repeater resources may be a subset of D2D communication resources that may be used by the mobile repeater WTRU. The dedicated mobile repeater resources may be separate resources from the resources that the mobile repeater may use for D2D communication. An eNB may reconfigure the dedicated mobile repeater WTRU resources. An RRC configuration message may be used to reconfigure the dedicated mobile repeater WTRU resources. When the eNB receives an update from the mobile repeater WTRU, the eNB may reconfigure the dedicated mobile repeater resources. The update may be for a change in the number of remote WTRUs managed by the mobile repeater WTRU. For example, the number of remote WTRUs may change with the addition / removal of remote WTRUs to / from the remote WTRUs managed by the mobile repeater WTRU. The resource pool dedicated to the mobile repeater WTRU may be dynamically changed / reconfigured when the number of services requested by the remote WTRUs changes. The resource pool dedicated to the mobile repeater WTRU may be dynamically modified / reconfigured as the estimated traffic of the mobile repeater WTRU changes. The modification and / or reallocation of resources may be performed via various techniques.

[0170] Resource allocation for the mobile repeater WTRU may be achieved by estimating the services provided by the mobile repeater WTRU. Upon attachment of a remote WTRU to the mobile repeater WTRU, an amount of resources that may be used to serve the remote WTRU may be estimated. The mobile repeater WTRU and / or the eNB may estimate the amount of resources that may be used to serve the remote WTRU. For example, the remote WTRU may request communication of eMBMS traffic that the mobile repeater WTRU is already transmitting to a different remote WTRU over a PC5 interface. An estimation may be made that the amount of resources used by the remote WTRU may not be significantly changed to satisfy the remote WTRU's requirements. The eNB may make the estimation.

[0171] These resource estimates may be based on an assumption that the resources used may be close to the maximum required for a given service requirement or set of service requirements. For example, an estimate may be made such that a maximum amount of resources for a given service may be added to the available resources when the given service begins. The mobile repeater WTRU may send an indication of an increase in the amount of resources when the mobile repeater WTRU is connected to an additional remote WTRU. The mobile repeater WTRU may send an indication of a set of additional services related to the additional remote WTRU. The resource estimate may take into account all possible services that may be used by the additional remote WTRU. The mobile repeater WTRU may use the resource estimate to define a resource pool configuration for the mobile repeater WTRU. The mobile repeater WTRU may take into account the number of remote WTRUs for which the mobile repeater WTRU serves. The mobile repeater WTRU may send an indication of an increase in the amount of resources when the mobile repeater WTRU is connected to an additional remote WTRU and / or an indication of a set of additional services related to the additional remote WTRU to the eNB via RRC signaling. The indication may be sent by the mobile repeater WTRU to the eNB via the MAC CE.

[0172] The indication may include various information. The indication may include the number of remote WTRUs for which the mobile repeater WTRU serves. The indication may include the amount of resources that may be used. The amount of resources that may be used may be based on the amount of additional resources that may be used as a result of additional remote WTRUs becoming connected to the mobile repeater WTRU and / or the amount of resources used by some or all of the remote WTRUs connected to the mobile repeater WTRU. The indication may include the resource pool loading that the mobile repeater WTRU is experiencing. The resource pool loading that the mobile repeater WTRU is experiencing may be based on the mobile repeater WTRU's knowledge of scheduling resources when the mobile repeater WTRU uses Mode 2. The indication may include additional services requested by additional / or remote WTRUs connected to the mobile repeater WTRU.

[0173] The mobile repeater WTRU may report the amount of resources and / or services that may be used to serve a remote WTRU. In the report, the mobile repeater WTRU may indicate the number of independent streams or destinations for which it serves. The mobile repeater WTRU may indicate the data rates required for some or all of the independent streams. The mobile repeater WTRU may or may not have the capability to transmit simultaneously to multiple destinations and / or independent streams. The eNB may use the report to provide the mobile repeater WTRU with sufficient time resources.

[0174] Scheduling of resources for D2D transmissions may be achieved by various modes. The modes may include Mode 1, Mode 2, or an enhanced mode. In Mode 1, the eNB may directly schedule resources in a resource pool to be used for transmission. The resource scheduling may be communicated over SA. In Mode 2, the eNB may configure a resource pool. The transmitting WTRU may autonomously determine the resources to be used during the scheduling period. The enhanced mode may be an improvement based on Mode 1 and / or Mode 2. The remote WTRU may be out of coverage and may or may not receive the pool configuration from the system information. Mode 1 and / or Mode 2 may be enhanced in the context of the mobile repeater WTRU and the scheduling resources used by the remote WTRU.

[0175] Scheduling of resources for D2D communication may be accomplished via various approaches, which may be based on the enhanced mode. Certain approaches may include an eNB configuring a resource pool and a WTRU that schedules resources in the resource pool. Certain approaches may include an eNB configuring a resource pool and a WTRU that segregates resources and assigns the segregated resources to a remote WTRU or a group of remote WTRUs. Certain approaches may include an eNB directly scheduling resources in a resource pool. For example, an eNB may directly schedule a resource pool of a mobile repeater WTRU, and the WTRU may schedule resources in the resource pool of other WTRUs.

[0176] Certain approaches may include an eNB configuring a resource pool and a WTRU scheduling resources in the resource pool. The WTRU may transmit D2D discovery or communication using a preconfigured pool and / or a pool signaled by the eNB. The preconfigured pool may include a device configured pool and / or a layer configured pool. For example, the preconfigured pool may be used when the WTRU is out of coverage. The eNB signaled pool may be used when the WTRU is in coverage. To allow a WTRU (e.g., a WTRU that is out of coverage of an eNB) to communicate with a mobile repeater WTRU (e.g., a WTRU that is in coverage of an eNB), a transmitter (TX) pool of a WTRU may exist in a receiver (RX) pool of a different WTRU. Having a TX pool of a WTRU exist in a RX pool of a different WTRU may be achieved via various approaches.

[0177] Various approaches to having a TX pool of a WTRU exist within an RX pool of a different WTRU may include a mobile repeater WTRU indicating its own pre-configured resources and / or the remote WTRU's pre-configured resources to an eNB. The mobile repeater WTRU may indicate its own pre-configured resources and / or the remote WTRU's pre-configured resources to an eNB via RRC signaling. The mobile repeater WTRU may indicate its own pre-configured resources to an eNB when its pre-configured resources match the remote WTRU's pre-configured resources. The remote WTRU may send its pre-configured resources to the mobile repeater WTRU during connection establishment with the mobile repeater WTRU. The eNB may configure the mobile repeater WTRU's resources based on knowledge of the pre-configured resources.

[0178] Various approaches to having a TX pool of a WTRU exist within an RX pool of a different WTRU may include an eNB receiving pre-configured resources to be used by one mobile repeater WTRU from the network and / or from a function. The eNB may configure the pool to be used by the mobile repeater WTRU based on information received from the network and / or from the function. The pre-configured pool may be specifically for a remote WTRU. If the pre-configured pool is specifically for a remote WTRU, the eNB may use an identity of the remote WTRU to determine the pool to be used by the mobile repeater WTRU for communication with the remote WTRU. The eNB may receive an identity of the remote WTRU from the mobile repeater WTRU (e.g., by means described herein).

[0179] The resource pool configuration may be communicated to the mobile repeater WTRU and / or the remote WTRU. The eNB may determine the resource pool to be used by the mobile repeater WTRU and the remote WTRU as discussed herein. The eNB may configure the mobile repeater WTRU with the resource pool configuration. The eNB may use R12 mechanisms of RRC signaling to configure the mobile repeater WTRU. The mobile repeater WTRU may forward the resource pool configuration to the remote WTRU. A control D2D communication message may be used to forward the resource pool configuration to the remote WTRU. For example, a D2D control message used to forward the resource pool configuration to the remote WTRU may be referred to as a D2D mobile repeater resource pool control message. The D2D mobile repeater resource pool control message may be destined for, for example, an RRC layer of the remote WTRU. The D2D mobile repeater resource pool control message may inform the remote WTRU about the resource pool to be utilized for future D2D communications. The control D2D message may be identified via several different forms.

[0180] The D2D mobile repeater resource pool control message may be identified via a certain SCI format (e.g., SCI format 1). The SCI format may be used to transmit the D2D mobile repeater resource pool control message. The remote WTRU may identify data corresponding to the D2D mobile repeater resource pool control message. The data may be forwarded to a radio resource control (RRC).

[0181] The D2D mobile repeater resource pool control message may be identified via some kind of group destination ID (e.g., L2 ID). The group destination ID may be used for the D2D mobile repeater resource pool control message. The group destination ID may be indicated in the SCI format. For example, the SCI format may be SCI format 0. The SCI format 0 may schedule resource blocks to be received / decoded on the SL-SCH. The group destination ID may enable some or all remote WTRUs to receive the control message. For example, a mobile repeater WTRU may send a message to some or all WTRUs for which it serves.

[0182] The D2D mobile repeater resource pool control message may be identified via certain fields or indicators in a Packet Data Convergence Protocol (PDCP) packet header. The field and / or indicator may indicate that a certain type of PDCP packet may be for RRC control. The field and / or indicator may indicate that the type of PDCP packet is not forwarded to the application layer (e.g., is instead forwarded to the RRC layer).

[0183] The D2D mobile repeater resource pool control message may be identified via the method utilized to send broadcast messaging. The D2D mobile repeater resource pool control message may be identified via RRC signaling directly from the eNB. The remote WTRU may be within the coverage of the eNB when the D2D resources are configured.

[0184] The remote WTRU may be signaled via a D2D mobile repeater resource pool control message to use pre-configured resources. The remote WTRU may be signaled prior to initial configuration. When the D2D mobile repeater resource pool control message is received and the remote WTRU's resource pool is reconfigured, the remote WTRU may listen to the reconfigured pool. The remote WTRU may transmit on the new pool to communicate with the mobile repeater. Subsequent reconfigurations may occur in the manner discussed herein.

[0185] Resource pool reconfiguration may include various types of reconfiguration. The remote WTRU may be reconfigured to monitor additional RX discovery and / or communication pools in addition to the preconfigured RX pools. The remote WTRU may use preconfigured TX pools to transmit. The remote WTRU may be reconfigured by an eNB (e.g., via a mobile repeater) to monitor a certain set of RX pools. The remote WTRU may transmit using a certain set of TX pools for discovery and / or communication. The mobile repeater WTRU may be reconfigured to monitor a certain set of RX pools. The mobile repeater WTRU may be reconfigured by an eNB or function. The set of RX pools may include the remote WTRU's preconfigured TX pools. The mobile repeater WTRU may use the TX pools configured by the original eNB to transmit.

[0186] Resource pool reconfiguration may be useful for out-of-coverage WTRUs. Out-of-coverage WTRUs may be reached through the use of pre-configured resources. For example, some or all mobile repeaters may use pre-configured resources for initial communication with a remote WTRU. The pre-configured resources may enable some or all mobile repeaters to establish a connection with a remote WTRU. Mobile repeater communication may use a large amount of resources. The eNB may control the large amount of resources without defining a pre-configured pool to guarantee sufficient bandwidth for mobile repeater operation. The eNB may control the resources for efficient resource management.

[0187] Resource pool reconfiguration may occur in various ways. Resource pool reconfiguration may occur during connection establishment. The remote WTRU may use pre-configured discovery and / or communication resource pools to perform mobile repeater discovery and / or connection establishment. During connection establishment, the remote WTRU may be reconfigured to use a reconfigured set of resource pools for further communications over the mobile repeater link after receipt of a reconfiguration message. The remote WTRU may be reconfigured at the end of the connection establishment procedure to use a reconfigured set of resource pools for some or all further communications over the mobile repeater link after receipt of a reconfiguration message. The remote WTRU may be reconfigured when the D2D communications for the connection establishment procedure are completed.

[0188] 10 is a diagram of an example of resource reconfiguration. The remote WTRU 1010 may send a connection establishment request message at 1002 using pre-configured D2D communication resources. The mobile repeater WTRU 1012 may query the eNB 1014 to grant the remote WTRU 1010 use of resources. The mobile repeater WTRU 1012 may receive the resource pool to be used by the mobile repeater WTRU 1012 and the remote WTRU 1010 along with the eNB grant at 1004. The mobile repeater WTRU 1012 may have previously received the resource pool to be used by the mobile repeater WTRU 1012. For example, the mobile repeater WTRU 1012 may have received the resource pool to be used by the mobile repeater WTRU 1012 when the mobile repeater WTRU 1012 was set up to operate as a mobile repeater. The mobile repeater WTRU 1012 may send a connection establishment complete message at 1006. The connection establishment complete message may include the new resource pool (e.g., reconfigured resources) to be used. After receiving the connection establishment complete message, the remote WTRU 1010 may monitor 1008 the RX pool and use the TX pool specified in the resource reconfiguration.

[0189] The resource pool reconfiguration may be achieved via mobile repeater discovery. For example, the mobile repeater WTRU may embed the resource reconfiguration in a mobile repeater discovery message. When the remote WTRU attempts to establish a connection with the mobile repeater, the remote WTRU may send a connection request using the reconfigured pool received in the discovery announcement / response from the mobile repeater.

[0190] A resource pool reconfiguration may occur during one-to-one communication between the mobile repeater WTRU and the remote WTRU. The mobile repeater WTRU may send a resource reconfiguration message during one-to-one communication between the mobile repeater WTRU and the remote WTRU. The mobile repeater WTRU may use pre-configured resources and / or resources previously reconfigured by the mobile repeater WTRU to send the resource reconfiguration. Upon receipt of the resource reconfiguration message, the remote WTRU may start transmitting and monitoring using the reconfigured pool.

[0191] The resource pool reconfiguration may occur when the remote WTRU is within the coverage of an eNB and / or can potentially connect to a mobile repeater. For example, the remote WTRU may be moving out of the coverage of an eNB. A portion of the remote WTRU's traffic (e.g., public safety traffic) may be moved to the mobile repeater. The resource pool reconfiguration may be received via dedicated RRC signaling to the remote WTRU and / or via broadcast signaling (e.g., system information block (SIB)).

[0192] The resource reconfiguration message may include one or more of a TX / RX discovery / communication pool description, a time validity for using the pool, and / or an eNB identifier.

[0193] The remote WTRU may store a resource reconfiguration that the remote WTRU received from the eNB and / or mobile repeater. The resource reconfiguration may correspond to the last resource reconfiguration received by the remote WTRU from the eNB and / or mobile repeater. The remote WTRU may store the resource reconfiguration in a memory of the remote WTRU. If a previous resource pool configuration exists in the memory of the remote WTRU, the remote WTRU may attempt to communicate the previous pool configuration to the mobile repeater. For example, the remote WTRU may search for a discovery signal using a previously pre-configured pool. The remote WTRU may attempt to perform a mobile repeater connection establishment using a previously pre-configured pool from the memory. If the connection establishment fails, another connection establishment may be retried using a previously pre-configured pool. If the connection establishment using a previously pre-configured pool from the memory fails, the remote WTRU may delete the previously pre-configured pool from the memory of the remote WTRU.

[0194] Scheduling of resources for D2D communication may be achieved via resource pool configuration with resource pool separation (e.g., Mode 2 with resource pool separation). The mobile repeater WTRU may receive a Mode 2 resource pool from the eNB. The mobile repeater WTRU may separate the resource pool to different remote WTRUs or groups of remote WTRUs. The mobile repeater WTRU may autonomously select multiple sub-pools from a pool configured by the eNB. The mobile repeater WTRU may configure different remote WTRUs separately with sub-pools that the mobile repeater WTRU selects from a pool configured by the eNB. The mobile repeater WTRU may configure different sub-groups of remote WTRUs separately with sub-pools that the mobile repeater WTRU selects from a pool configured by the eNB. The mobile repeater WTRU may determine an amount of resources to allocate to different remote WTRUs. The determination of the amount of resources to allocate to different remote WTRUs may be based on expected traffic from the remote WTRUs.

[0195] The eNB and / or network may select how the resource pool is separated between the mobile repeater WTRU and some or all of the remote WTRUs. The eNB may configure the transmission resource pools of the remote WTRU and the mobile repeater WTRU to avoid resource collisions between and / or within a transmission. For example, the transmission resource pool of the remote WTRU and the transmission resource pool of the mobile repeater WTRU may be configured to be orthogonal to avoid resource collisions.

[0196] Multiple remote WTRUs may be assigned to the same transmission resource pool if they are known to have no risk of interference, e.g., they may not transmit at the same time, and their relative locations may be such that there is no risk of interference.

[0197] The eNB may assign the resource pool according to a potentially static priority associated with the WTRU. For example, a mobile repeater WTRU may have a potentially static priority higher than a remote WTRU. The eNB may signal the resource pool to be used by the mobile repeater WTRU to the mobile repeater WTRU. The eNB may then signal the resource pool to be used by the remote WTRU. The eNB may signal the resource pool to be used by a group of remote WTRUs.

[0198] The eNB can send multiple resource pools that can be used by the mobile repeater to the remote WTRU communication. The mobile repeater WTRU can determine how to subdivide the resource pools among the remote WTRU. The mobile repeater WTRU can send pool configurations for the remote WTRU to determine which transmit pools it can use. The mobile repeater WTRU can send pool configurations for the remote WTRU to determine which receive pools it can listen to.

[0199] The remote WTRU may be configured with a selected transmit / receive pool, which may enable it to receive transmissions from the mobile repeater WTRU (e.g., based on the mobile repeater WTRU transmit pool). For example, the eNB may configure four transmit pools (e.g., for SA and for data) to the mobile repeater WTRU to be used for mobile repeater communications. The mobile repeater WTRU may determine to use one of the transmit pools for transmission of its own communication toward the remote WTRU. The remaining transmit pool may then be used for the remote WTRU's transmissions. A portion or group of remote WTRUs may be selected for the remaining pools. In another example, the mobile repeater WTRU may use all four pools for its transmissions and configure each remote WTRU with a single receive pool. The mobile repeater WTRU may then select the transmit pool to use for the remote WTRU that is the intended recipient of the transmission.

[0200] If the number of remote WTRUs is greater than the number of pools, the selection may be performed based on some sort of allocation. The allocation may be a random allocation of WTRUs to each remaining pool to ensure that approximately the same number of remote WTRUs are assigned to each remaining pool. The priority may be based on the expected loading of remote WTRUs and / or mobile repeater WTRUs' transmissions. The expected loading of remote WTRUs and / or mobile repeater WTRUs' transmissions may be obtained from the eNB and / or from a layer within the mobile repeater WTRU. Relatively equal amounts of traffic transmission load may be assigned to the transmission pools. For example, a WTRU with a large traffic expectation may be in a pool by itself. A set of WTRUs with a smaller traffic expectation may be assigned to another pool.

[0201] The eNB may send one or more pools to the mobile repeater WTRU. A single pool may be subdivided among multiple remote WTRUs. This subdivision may be done by the mobile repeater WTRU. This subdivision may be done by the eNB. The pool may be subdivided based on some assignment. The assignment may be allocating a set of allowed T-RPTs to the remote WTRU. For example, the remote WTRU may be restricted to use a certain value of k or a certain set of T-RPT indices. The assignment may be based on a set of allowed scheduling periods. For example, a remote WTRU may be assigned a scheduling period or a set of scheduling periods that are distinct from another remote WTRU. The assignment may be based on a set of allowed frequency resources. For example, the allowable frequency resources in a D2D subframe that may be used by a WTRU may be distinct from the allowable frequency resources that may be used by another WTRU. The assignment may be based on a hopping pattern. For example, the selected hopping pattern used by the remote WTRU may be such that the actual selected resources of different remote WTRUs may be distinct.

[0202] The mobile repeater WTRU and / or eNB may select the resource pool separation based on certain criteria. The criteria may include the relative load of remote WTRU transmissions. For example, the mobile repeater WTRU and / or eNB may ensure relatively equal loading of each subdivision by assigning multiple remote WTRUs with different loads to subdivisions such that the load of each subdivision is relatively equal to each other. The criteria may include priority of the remote WTRU or remote WTRU traffic. For example, high priority WTRUs may be given their own subdivision or a subdivision with a small number of other WTRUs to avoid interference with other WTRUs. The criteria may include some fixed / static rule. For example, a subdivision may be assigned to a fixed number of WTRUs.

[0203] Scheduling of resources for D2D communication may be achieved via Mode 1 resource pool configuration for mobile repeater transmissions and Mode 2 resource pool configuration for remote WTRU transmissions. The eNB may continue to use Mode 1 for mobile repeater transmissions (e.g., transmission of resources from the mobile repeater WTRU to the remote WTRU). The eNB may enable the remote WTRU to transmit to the mobile repeater WTRU using Mode 2. For example, the mobile repeater WTRU may be used primarily for broadcast traffic and some uplink traffic from the remote WTRU to the eNB. The uplink traffic from the remote WTRU to the eNB may include a one-to-one communication link to a network or application server. The eNB may configure a resource pool to be used for reception by the remote WTRU and transmission by the remote WTRU. The resource pool may be forwarded to the remote WTRU. The eNB may then schedule transmissions by the mobile repeater via DCI format 5.

[0204] Service continuity may be maintained by various approaches. The mobile repeater WTRU and / or the remote WTRU may implement certain procedures to maintain service continuity for the remote WTRU. Service continuity may be maintained in various situations. The mobile repeater may lose connection to the eNB. For example, the remote / mobile repeater WTRU may go out of coverage of the eNB. The mobile repeater may be disabled by the eNB. The remote WTRU may transfer from using one mobile repeater to another. The remote WTRU may transition between an in-coverage connection with the eNB and a connection through the mobile repeater. For example, the transition may be between Uu and PC5 transition. The mobile repeater WTRU may be handed over from one eNB to another eNB. The eNB may assist or control these procedures.

[0205] Service continuity may be maintained when the mobile repeater loses connection with the eNB. The mobile repeater WTRU may send a notification via PC5 when the mobile repeater WTRU detects loss of eNB connection. The mobile repeater WTRU may send a notification or information to the remote WTRU when it determines that the mobile repeater WTRU may be leaving the coverage of the eNB. The Uu loss notification may be sent via PC5 and / or via a discovery transport or a communication transport. The Uu loss notification may comprise a MAC CE. The Uu loss notification may be sent using PHY layer signaling. For example, the Uu loss notification may be sent using PHY layer signaling as part of the D2DSS or other channel. The Uu loss notification may be sent using RRC layer control signaling. The mobile repeater WTRU may independently send a message to the remote WTRU. The mobile repeater WTRU may use a mobile repeater specific broadcast mechanism to send the message.

[0206] The Uu loss notification may be sent in response to some trigger. The trigger may include the signal quality of the Uu interface as seen by the mobile repeater. For example, the signal quality of the Uu interface may be seen by the mobile repeater via existing LTE measurements of downlink signal quality. The trigger may include a trigger for an RRC re-establishment procedure. The trigger may be fixed and / or configured by the network via signaling. For example, the signaling may include RRC signaling over Uu. The mobile repeater WTRU may trigger the Uu loss notification sent to the remote WTRU when an explicit message is received from the eNB indicating that the mobile repeater's mobile repeater operation may be stopped.

[0207] The mobile repeater WTRU behavior and / or measured signal quality thresholds that trigger a Uu loss notification may be set by the network. The network may set the thresholds and potential hysteresis values ​​to avoid a Uu loss notification being triggered for a temporary degradation in signal quality. The network may configure multiple thresholds. Multiple thresholds may be used to trigger different behaviors in the remote WTRU. The behaviors may be communicated to the remote WTRU along with the Uu loss notification. For example, if the Uu signal quality measured by the mobile repeater is determined to be poor or below a threshold for a time period exceeding the hysteresis, the mobile repeater WTRU may send a Uu loss notification over the PC5 interface to the remote WTRU along with an indication to perform a behavior. If the threshold is not exceeded but another threshold is exceeded, the Uu loss notification may still be sent, but with an indication to perform another behavior.

[0208] Upon receiving the Uu loss notification, the remote WTRU may perform certain actions. The behavior parameters indicated with the Uu loss notification may be used to dictate which behavior or combination of behaviors the remote WTRU may take. The remote WTRU may start discovery of another mobile repeater. For example, it may send a Model B discovery request and start listening for Model B discovery responses from different mobile repeaters. The remote WTRU may initiate a mobile repeater reselection procedure. The remote WTRU may listen for Model A discovery announcements from the mobile repeater WTRU. The remote WTRU may measure the link quality (e.g., on PC5) of different available mobile repeaters based on the discovery messages sent from the mobile repeaters and start sending the measurements to higher layers. The higher layers of the remote WTRU may perform mobile repeater selection together with the measurements provided by the lower layers. The remote WTRU may attempt to establish one-to-one communication with the selected mobile repeater WTRU.

[0209] The following may be examples of the use of multiple thresholds to trigger different behaviors in a remote WTRU. For example, if a threshold is exceeded, the remote WTRU may initiate discovery of another mobile repeater, listen to Model A discovery announcements, measure link quality, and wait for mobile repeater selection. If another threshold is exceeded, the remote WTRU may initiate discovery of another mobile repeater, listen to Model A discovery announcements, measure link quality, wait for mobile repeater selection, and attempt to establish one-to-one communication with the selected mobile repeater WTRU. If another threshold is exceeded and multiple activities have already been performed based on receiving a previous Uu loss notification, the remote WTRU may attempt to establish one-to-one communication with the selected mobile repeater WTRU based on the already selected mobile repeater.

[0210] The mobile repeater WTRU may send the information provided by the eNB along with the Uu loss notification to the remote WTRU. The eNB may provide the information to the remote WTRU during normal operation of the mobile repeater and / or during poor connectivity with the eNB.

[0211] During normal operation of the mobile repeater, the eNB may send to the mobile repeater WTRU a list of candidate WTRU IDs that can replace the mobile repeater to which the remote WTRU is connected if the mobile repeater WTRU goes out of coverage. The list may be periodically updated by the eNB and sent to the mobile repeater WTRU. The list may be sent via RRC signaling over the Uu interface. The list may be updated by the function and sent via the PC3 interface.

[0212] Upon detection of poor radio conditions and / or connectivity issues with the eNB, the mobile repeater WTRU may be configured to transmit a D2D control message (e.g., via PC5) to signal loss of coverage of the mobile repeater. The D2D control message used to indicate loss of coverage may be referred to as a D2D Uu backhaul loss control message. The poor radio conditions and / or connectivity issues may be detected when an RLF condition is triggered, when one or more of T310, T311, or T301 are running, when T300 expires, and / or when the mobile repeater WTRU uses exception resources. The D2D Uu backhaul loss control message may be broadcast to the remote WTRU. For example, the broadcast may use a predefined destination address. The control message may be sent individually to the remote WTRU using a one-to-one communication path. For example, the one-to-one communication path may include a dedicated WTRU ID. The D2D Uu backhaul loss control message may include certain information. The D2D Uu backhaul loss control message may include loss of coverage indication. The D2D Uu backhaul loss control message may include a proposed WTRU ID with which the remote WTRU may attempt to establish a connection to continue service. The WTRU ID may be periodically provided by the eNB to the mobile repeater WTRU when the mobile repeater WTRU is connected to the eNB. The WTRU ID may be provided when the mobile repeater WTRU in question is losing connection with the eNB. The D2D Uu backhaul loss control message may include a list of resources or resource pools that may be used to communicate with the mobile repeater WTRU. For example, the remote WTRU may be asked to directly establish one-to-one communication with the mobile repeater WTRU without performing a full discovery procedure. The eNB may prefer one-to-one communication. The pool for one-to-one communication may be different from the pre-configured pool.

[0213] The remote WTRU may receive a D2D Uu backhaul loss control message signaling loss of coverage of the eNB by the mobile repeater. The remote WTRU may initiate discovery and / or one-to-one communication with the proposed WTRU that may act as a replacement mobile repeater. The eNB may inform the replacement mobile repeater of its role to support the remote WTRU. The eNB may configure the replacement mobile repeater with appropriate resources. For example, the replacement mobile repeater may be required to start monitoring for an identical Temporary Mobile Group Identity (TMGI) before connecting to the remote WTRU. The replacement mobile repeater may start transmitting TMGI and / or E-UTRAN Cell Global Identifier (ECGI). For example, pre-configuration by initiating discovery and / or one-to-one communication with the replacement WTRU may enable the replacement mobile repeater WTRU to buffer broadcast data prior to the connection procedure initiated by the remote WTRU.

[0214] Service continuity may be maintained when a mobile repeater is disabled by an eNB. The eNB may enable mobile repeater context transfer. The eNB may trigger a Uu loss notification to force a set of remote WTRUs to disconnect from the mobile repeater. The eNB may decide to disable or deactivate the mobile repeater WTRU based on the quality of the connection between the mobile repeater WTRU and the eNB. For example, the eNB may evaluate the link quality of the Uu link between the mobile repeater WTRU and the eNB. The evaluation may be performed periodically. The evaluation of the quality may be based on periodic measurements of Uu link quality sent by the mobile repeater WTRU to the eNB. The evaluation of the link quality may be based on detection of loss of communication with the mobile repeater. For example, loss of communication with the mobile repeater may be detected when the mobile repeater no longer acknowledges transmissions made by the eNB. The eNB may disable the mobile repeater WTRU when the link quality falls below an acceptable threshold. The eNB may select a replacement mobile repeater WTRU for a mobile repeater WTRU that the eNB is disabling or deactivating. The eNB may forward information to and / or configure the replacement mobile repeater WTRU.

[0215] The eNB may send certain information to the replacement mobile repeater WTRU. The eNB may send a mobile repeater activation message. For example, the eNB may send a mobile repeater activation message if the replacement mobile repeater was not initially acting as a mobile repeater. The mobile repeater activation message may trigger the WTRU to start behaving as a mobile repeater and start sending Model A announcement messages and / or start listening to Model B request messages. The eNB may send a mobile repeater forwarding indication. For example, the eNB may send a mobile repeater forwarding indication if the replacement mobile repeater WTRU is acting as a mobile repeater and may start serving different and / or additional remote WTRUs. The eNB may send a list of remote WTRUs served by the mobile repeater. The list may include identifiers (e.g., L2 ID, PHY layer ID, and / or the like) of the remote WTRUs. The list may include remote WTRUs being forwarded to the replacement mobile repeater WTRU. The eNB may send resources or resource pools that the mobile repeater WTRU can use to transmit D2D communication or D2D discovery. The eNB may send resources or resource pools on which the mobile repeater WTRU can listen for D2D communication or D2D discovery. For example, the replacement mobile repeater WTRU may start using the resource pool used by the deactivated mobile repeater. The replacement mobile repeater WTRU may use the resource pool for transmission / reception with the remote WTRU. The eNB may send services provided to the remote WTRU and context information associated with those services. For example, the deactivated mobile repeater may have been monitoring TMGI to provide broadcast information. The replacement mobile repeater may or may not monitor the same TMGI. The eNB may indicate one or more of the following information to the replacement mobile repeater WTRU:The eNB may indicate to the replacement mobile repeater WTRU the TMGI that the mobile repeater WTRU may be configured to monitor. For example, the TMGI that the replacement mobile repeater WTRU may be configured to monitor may be different from the TMGI that the deactivated mobile repeater may have monitored. The eNB may indicate to the replacement mobile repeater a group ID for PC5 transmissions that may have been used by the disabled mobile repeater to communicate to send eMBMS data to the remote WTRU. The remote WTRU may or may not issue a different TMGI monitoring request to the replacement mobile repeater. The eNB may indicate to the replacement mobile repeater a specific ID (e.g., L2 ID, PHY ID, and / or the like) of the remote WTRU that is receiving the broadcast of the TMGI. The eNB may indicate to the replacement mobile repeater an address used for the mobile repeater broadcast mechanism.

[0216] The replacement mobile repeater WTRU may receive the mobile repeater activate message and / or the mobile repeater redirect message. The replacement mobile repeater WTRU may perform certain actions. The replacement mobile repeater WTRU may start sending Model A announcements or listening for and responding to Model B solicitation messages if a mobile repeater activate message is received. The replacement mobile repeater WTRU may start monitoring the TMGI that the eNB indicated to the replacement mobile repeater WTRU. The replacement mobile repeater WTRU may start sending broadcast information read from the Uu interface for the TMGI on PC5 using the associated group ID. The replacement mobile repeater WTRU may use the group ID (e.g., indicated by the eNB) for PC5 communications. The replacement mobile repeater WTRU may send future broadcast control messages (e.g., Uu loss notification messages as described herein). The replacement mobile repeater WTRU may use the broadcast address it previously used, and the replacement mobile repeater WTRU may use the broadcast address that was used by the mobile repeater that is being disabled. The replacement mobile repeater WTRU may send a broadcast message to the remote WTRUs served by the disabled mobile repeater. The broadcast message may indicate that the remote WTRUs may change their monitored broadcast control address to the broadcast control address of the replacement mobile repeater WTRU.

[0217] After the replacement mobile repeater WTRU is set up, the eNB may send a mobile repeater deactivation message to the mobile repeater that the eNB is disabling. The mobile repeater that the eNB is disabling may receive the mobile repeater deactivation message. The mobile repeater that the eNB is disabling may stop sending Model A discovery messages. The mobile repeater that the eNB is disabling may stop responding to Model B solicitation messages. Ongoing mobile repeater operation may be stopped. For example, one-to-one communication with the mobile repeater that the eNB is disabling may be stopped. The mobile repeater that the eNB is disabling may stop monitoring the broadcast of TMGI for its mobile repeater operation. The mobile repeater that the eNB is disabling may stop sending broadcast data over the PC5 link.

[0218] When a mobile repeater WTRU is disabled and the eNB forwards the remote WTRU's information to a different and / or additional mobile repeater, a Uu loss notification message may be sent by the mobile repeater that the eNB is disabling. Behavior regarding transmission (e.g., by the mobile repeater WTRU) and reception (e.g., by the remote WTRU) may be applicable.

[0219] Service continuity may be maintained when a remote WTRU relocates from a mobile repeater to another mobile repeater. Mobile repeater link replacement and termination may be performed. Session continuity and / or address maintenance may be performed at the application layer. For example, session continuity and / or address maintenance may be performed when a remote WTRU can perform reselection to a different mobile repeater (e.g., a reselected mobile repeater) based on the link quality of the link between the remote WTRU and the previous mobile repeater. The reselected mobile repeater may be notified of the previous or current mobile repeater selection and / or termination of the link with the previous mobile repeater.

[0220] The remote WTRU may decide to perform reselection to a different mobile relay (e.g., the reselected mobile relay). The remote WTRU may send information regarding the mobile relay link that is about to be released. The remote WTRU may send a mobile relay link forwarding indication to the reselected mobile relay. The mobile relay link forwarding indication and information may be forwarded to a mobility management gateway or serving gateway (MME / S-GW) to reserve an address. Different and / or additional bearers may be established via the reselected mobile relay. The mobile relay link forwarding indication and information may be forwarded to the MME / S-GW to maintain the existing PDN connection. The mobile relay link forwarding indication and information may be sent during the establishment of a one-to-one communication connection. The mobile relay link forwarding indication and information may be sent during additional message exchanges that occur some time between discovery and one-to-one communication establishment between the remote WTRU and the mobile relay WTRU.

[0221] A procedure may be used for service continuity. This procedure may incorporate sending a mobile repeater link transfer indication with information about the mobile repeater link being released, and terminating the mobile repeater link being released when the link with the reselected mobile repeater is established. This procedure may include multiple steps. The following may be an example:

[0222] The remote WTRU may have established a connection with the mobile repeater with which the PDN connection is associated using the EPC. The remote WTRU may initiate a reselection to another mobile repeater (e.g., the reselected mobile repeater) based on a trigger described herein. The remote WTRU may initiate a one-to-one connection to the reselected mobile repeater. The remote WTRU may indicate during the one-to-one connection establishment that a connection is being established to replace the link with the mobile repeater. The remote WTRU may indicate information about the mobile repeater and / or indicate a mobile repeater link transfer. The indication may include one or more of the remote WTRU's IP address, the remote WTRU's identification (e.g., L2 ID, PHY layer ID, and / or the like), and the mobile repeater 1's identifier (e.g., L2 ID, PHY layer ID, or destination group ID). The indication may be transferred via PC5 signaling protocol or via higher layer messages. Information from lower layers may be obtained by upper layers of the remote WTRU after a decision is made to connect to a different mobile repeater. The reselected mobile repeater may trigger a routing reconfiguration in the EPC to reroute packets of the remote WTRU through the reselected mobile repeater via NAS signaling. The actual routing reconfiguration may be performed at different times. The actual routing reconfiguration may be performed immediately or it may be delayed until the mobile repeater connection is fully set up with respect to the reselected mobile repeater. After the routing reconfiguration in the EPC, the reselected mobile repeater may verify the correct configuration of the mobile repeater for the remote WTRU. The remote WTRU may disconnect from the mobile repeater and indicate the end of the link disconnection to the mobile repeater. Upon receiving the end indication, the mobile repeater may send a NAS message to enable the previously configured route reconfiguration.

[0223] The remote WTRU may continue to be served by the mobile repeater until the remote / mobile repeater WTRU sends a mobile repeater termination indication. For example, the remote WTRU may transmit uplink data via and / or receive downlink data from the mobile repeater until the remote WTRU sends a mobile repeater termination indication. When a mobile repeater termination message is sent to the mobile repeater, the remote WTRU may assume that some or all communications mapped to mobile repeater communications for certain logical channels are sent via the reselected mobile repeater.

[0224] Mobile repeater link transfer and termination may be used to ensure service continuity between Uu and PC5 connections.

[0225] Service continuity between the Uu connection and the PC5 connection may be maintained. Criteria may be established for initiation of mobile repeater selection and connection establishment. When a WTRU is connected to an eNB, fast establishment of a mobile repeater connection may enable the WTRU to minimize service interruptions. For example, fast establishment of a mobile repeater connection may enable the WTRU to minimize service interruptions upon degradation of the Uu link when the WTRU is connected to an eNB via a Uu connection. The mobile repeater connection may include mobile repeater selection and connection establishment. A WTRU connected to an eNB may perform several steps in preparation for a potential service outage.

[0226] A WTRU connected to an eNB may perform mobile repeater selection continuously or periodically. Mobile repeater selection may be autonomous or via eNB assistance and / or control. The periodicity of mobile repeater selection may be statically configured in the WTRU. For example, the periodicity of mobile repeater selection may be statically configured and / or provided to the WTRU upon connection establishment. The periodicity of mobile repeater selection may be statically configured in a function. The periodicity of mobile repeater selection may be configured by the eNB using RRC signaling. The RRC signaling may be dedicated or broadcast. The periodicity of mobile repeater selection may depend on the value of eNB link quality or measurements by the WTRU. For example, different frequencies of mobile repeater selection may apply to different ranges of measured Uu link quality. The WTRU may maintain information of the most recent selected mobile repeater and utilize the information to initiate mobile repeater selection based on the occurrence of some trigger. For example, the trigger may be a move to a mobile repeater. In response to the trigger, the WTRU may attempt a mobile repeater connection with the last selected mobile repeater. After the mobile repeater connection is successful, the WTRU may move the associated Uu traffic to the selected mobile repeater WTRU.

[0227] A WTRU connected to an eNB may initiate the selection process upon the occurrence of a trigger, and then perform connection establishment and movement to the selected mobile repeater upon the occurrence of another trigger.

[0228] A WTRU connected to an eNB may perform connection establishment with a mobile repeater periodically or based on some trigger. The WTRU may continue to send some or all traffic over the Uu connection until another trigger occurs. The connection may be maintained indefinitely or may be periodically released and re-established based on potential mobile repeater selection or potential mobile repeater reselection. Data may or may not be sent over an active mobile repeater connection until a data transfer trigger occurs. Periodic keep-alive messages may be sent over the connection to maintain the quality of the mobile repeater connection. Periodic keep-alive messages may be sent to prompt reselection to a different mobile repeater. For example, keep-alive messages may comprise discovery or communication messages sent by a mobile repeater WTRU or a remote WTRU to allow a receiver to measure the quality of the repeater connection and determine whether reselection to another mobile repeater may be performed. Keep-alive messages may be application control or AS messages that may or may not contain valid data. Such messages may be expected by the intended recipient and the absence of such messages may trigger a reselection. Such messages may also comprise PHY or reference signals, allowing the receiver to measure the signal quality of the mobile repeater connection.

[0229] The trigger may include one or more of the following: The trigger may include a direct command by the eNB. For example, the direct command by the eNB may be via a message. The message may include an RRCReconfiguration message. The trigger may include an indication that the Uu quality measured by the WTRU may be below a threshold. The trigger may include lower layers declaring out of sync and / or radio link failure. The trigger may include an RRC connection re-establishment failure and / or expiration of a timer associated with the RRC connection re-establishment. The trigger may include an RLC unrecoverable error. The trigger may include a handover failure.

[0230] Certain procedures for connection establishment notification and release may be implemented. The remote WTRU may move between in-network coverage and a mobile repeater connection. The remote WTRU may initiate a transition between in-network coverage and a mobile repeater connection. The remote WTRU may be prompted by the eNB to transition between in-network coverage and a mobile repeater connection. For example, the remote WTRU may move from in-network coverage to a mobile repeater connection. The remote WTRU may notify higher layers in the network / application server / remote WTRU that the remote WTRU has left coverage. The upper layers may be notified when data may be sent over a different connection / bearer / IP address. The AS may initiate a different connection.

[0231] When moving from in-network coverage to a mobile repeater connection, the remote WTRU may inform the eNB that the mobile repeater connection was successful after it establishes a connection to the mobile repeater WTRU. The RRC connection on the Uu interface and / or the EPC connection via the UTRAN may be released. Transfer of data from the EPC may be initiated via the mobile repeater connection. The WTRU may follow certain procedures / processes when connecting to the mobile repeater.

[0232] For example, the remote WTRU may initiate the mobile repeater selection. The mobile repeater selection may be assisted by the network. The remote WTRU may send information regarding its RRC connection with the eNB to the mobile repeater WTRU (e.g., via a PC5 connection) during a one-to-one established connection. The information regarding the RRC connection with the eNB may be sent as part of higher layer signaling to enable the mobile repeater WTRU to initiate a transfer of traffic / sessions from the E-UTRAN connection. The information regarding the RRC connection with the eNB may include an identifier (e.g., L2 ID, PHY ID, 3GPP ID, and / or the like) of the remote WTRU attempting to connect to the mobile repeater WTRU. The information regarding the RRC connection with the eNB may include an address of the remote WTRU previously assigned by the E-UTRAN connection. The information regarding the RRC connection with the eNB may include an identification of a radio bearer on the E-UTRAN whose traffic is being transferred via PC5. The information regarding the RRC connection with the eNB may include an identification of the eNB to which the remote WTRU is connected.

[0233] The remote WTRU may receive the connection establishment success. The remote WTRU may indicate that the mobile repeater WTRU has been properly configured for network access. The remote WTRU may send a message to the eNB to inform the eNB about the successful establishment of the mobile repeater connection. The mobile repeater WTRU may send the message over a Uu link with the eNB on behalf of the remote WTRU. The message may include various information. The message may include an identification of the mobile repeater WTRU. The message may include an identification of the eNB serving the mobile repeater WTRU. The message may include resource information (e.g., resource pool) used to communicate with the mobile repeater WTRU. The message may include timing information (e.g., synchronization source information) of the mobile repeater WTRU. The message may include a timing difference for the eNB serving the remote WTRU. The message may include protocol status or configuration information (e.g., PDCP status, sequence number, and / or configuration information).

[0234] The remote WTRU may perform certain actions. The actions may include autonomously releasing the RRC connection after sending the message. The actions may include deleting some or all information associated with the radio bearers that were used for the services being forwarded to the mobile repeater WTRU. The actions may include waiting for an explicit signal from the eNB to release the RRC connection or release the bearers. For example, the eNB may signal the remote WTRU to release the RRC connection and send a message indicating that the release is for connecting to the mobile repeater WTRU. The actions may include continuing to use the Uu connection for some or all services until a criterion is met. The criterion may relate to the release of the RRC connection and / or the release of the Uu radio bearers and communication via the mobile repeater WTRU. Some examples of the criteria are RSRP thresholds, out-of-coverage detection, RLF, and / or the like. The actions may include notifying upper layers about the presence of a different PC5 link and / or associated bearers. Actions may be performed by the remote WTRU upon receipt of the connection establishment success. The remote WTRU may use a different PC5 and / or associated bearer to send application data. The remote WTRU may or may not use the Uu link bearer. Actions may include notifying the AS to forward unsent data in the Uu radio bearer buffer (e.g., RLC) to a different PC5 bearer.

[0235] The remote WTRU may begin to assume that some or all communications performed with the EPC may be accomplished via the mobile repeater WTRU (e.g., via the PC5 interface). The remote WTRU may begin to assume that some or all communications performed with the EPC may not be via the Uu interface. The remote WTRU may begin to assume that certain radio bearers have been released.

[0236] When moving from a mobile repeater connection to network coverage, the WTRU may provide a mobile repeater identification and mobile repeater information to the eNB. The provision of the mobile repeater identification and mobile repeater information to the eNB may be similar to a mobile repeater WTRU to mobile repeater WTRU transfer. The WTRU may establish an RRC connection with the eNB. The WTRU may send the mobile repeater information to the network via the eNB to transfer the EPC connection from the mobile repeater to the eNB. The WTRU may send the mobile repeater information to the network via the eNB to create a different EPC connection. The remote WTRU may follow certain procedures / processes after determining that it is in network coverage.

[0237] After the remote WTRU determines that it is within network coverage, it may initiate an RRC connection procedure with the eNB.

[0238] The remote WTRU may send information about the mobile repeater to which it is connected. The information may be sent as part of a NAS message in an RRC Connection Setup Complete message. The eNB may forward this information to the MME to initiate a reconfiguration of the routing of packets associated with the address. This information may include an identifier of the mobile repeater WTRU (e.g., L2 ID, PHY layer ID, or destination group ID). This information may include a list of services provided by the mobile repeater (e.g., a list of monitored TMGIs). This information may include a current address assigned to the remote WTRU by the mobile repeater WTRU. This information may include an identity of the remote WTRU (e.g., L2 ID, PHY layer ID, and / or the like). This information may include bearer information for the D2D link and / or the link from the mobile repeater to the eNB. This information may include protocol status and / or configuration information (e.g., PDCP status, sequence number, and / or configuration information).

[0239] The remote WTRU may send a termination indication to the mobile repeater WTRU to issue a disconnect / release from the mobile repeater WTRU. For example, the termination indication may be sent after completion of the RRC connection and / or successful initiation of service through the eNB. The termination indication may be used by the mobile repeater WTRU for various purposes. The termination indication may be used by the mobile repeater WTRU to force release of D2D resources maintained in the mobile repeater WTRU for communication with the remote WTRU that is now in its coverage. The termination indication may be used by the mobile repeater WTRU to notify the eNB. For example, the mobile repeater WTRU may be served by a different eNB than the eNB in ​​whose coverage the remote WTRU is in. The termination indication may be used by the mobile repeater WTRU to confirm to the network that the transfer from the mobile repeater connection to the Uu connection is complete.

[0240] Upon receiving the termination indication, the mobile repeater WTRU may perform certain actions. The mobile repeater WTRU may release some or all resources / pool that may have been used to communicate with the remote WTRU, or the mobile repeater WTRU may reconfigure its pool. For example, the reconfiguration may be based on the fact that the remote WTRU may no longer use D2D resources. The mobile repeater WTRU may send a message to the eNB serving the mobile repeater if the eNB is different from the eNB in ​​whose coverage the remote WTRU is in. Some resources may be released in the eNB serving the mobile repeater. The resource pool may be reconfigured by the mobile repeater WTRU. The mobile repeater WTRU may send a NAS message to the network to initiate transfer of the remote WTRU's data over the E-UTRAN connection.

[0241] User plane data transfer may be implemented. Data may need to be transferred between bearers / logical channels in a manner that avoids loss of data in transit. Uu radio bearers serving specific applications and / or services over Uu may be replaced with a combination of PC5 bearers between the remote WTRU and the mobile repeater WTRU and Uu radio bearers between the mobile repeater and the eNB.

[0242] Certain processes and / or procedures may be implemented to avoid loss of data during the transition. Different processes and / or procedures may be implemented for the transfer of data from Uu to PC5 and / or from PC5 to Uu. Downlink data may be treated differently than uplink data.

[0243] A completely lossless approach may be used to handle downlink data forwarding from Uu to PC5. For example, the eNB may forward RLC PDUs that have not yet been transmitted or that have been transmitted but not yet acknowledged via the mobile repeater on the Uu link. The eNB may forward the RLC PDUs while / after it releases the radio bearer and / or indicate the destination remote WTRU for which the RLC PDU is intended. Forwarding the RLC PDUs may include multiple steps. The steps may include the following:

[0244] The remote WTRU may notify the eNB that a radio bearer may be released because its service may be supported over a mobile repeater (e.g., as described herein). The radio bearer may be released by the eNB. For example, the radio bearer may be released by the eNB by sending an RRC connection reconfiguration. The eNB may allow the WTRU to move naturally to the RLF. The eNB may keep the radio bearer active and / or stop transmitting data over the radio bearer. The remote WTRU may delete some or all data associated with the Uu radio bearer upon receiving the RRC connection reconfiguration and release the bearer. The remote WTRU may delete some or all data associated with the Uu radio bearer upon receiving data packets over a PC5 link destined for the same application layer entity. The remote WTRU may delete some or all data associated with the Uu radio bearer immediately after sending a notification to the eNB that the radio bearer may be released. The eNB may forward some or all PDUs not yet transmitted over Uu to the mobile repeater WTRU (e.g., after the notification). A different bearer may be created to forward some or all PDUs not yet sent over Uu to the mobile repeater WTRU. The bearer that was working for the mobile repeater may be used to forward some or all PDUs not yet sent over Uu to the mobile repeater WTRU. The eNB may continue to create different and / or additional RLCs from packets received (e.g., over Uu) with the old WTRU address until the application server stops generating packets.

[0245] The mobile repeater WTRU may be informed that multiple packets may be sent to the remote WTRU via PC5. The packets may include the WTRU's old address. The packets may be uniquely identified using an identifier of the remote WTRU (e.g., L2 ID, PHY ID, or other ID). The packets may be identified through the use of control messages from the eNB to the mobile repeater WTRU. The control messages may include RRC, PDCP status reports, and / or the like. The messages may indicate expected packets by PDCP SN, count value, and / or the like. The mobile repeater WTRU may or may not rely on the correct address to route the data.

[0246] The mobile repeater WTRU may forward the packet to a logical channel / PC5 ​​bearer associated with the remote WTRU. The packet may be forwarded for transmission to the remote WTRU. The packet may be forwarded before additional and / or different packets are created from the data sent to the mobile repeater serving the remote WTRU. The additional and / or different packets may be created from the data using additional and / or different WTRU IP addresses destined for PC5.

[0247] The remote WTRU may receive packets forwarded by the eNB from the mobile repeater WTRU. The remote WTRU may continue with the sequencing / numbering and forwarding to upper layers, which occurred over the Uu radio bearer.

[0248] A time-based lossless approach may be used to handle the downlink data transfer from Uu to PC5. For example, the eNB may send some or all PDUs that have not yet been transmitted or PDUs that have been transmitted but not acknowledged (e.g., signaled to the WTRU) over the Uu radio bearer for a certain time before it releases the radio bearer. The sending of the PDUs may involve multiple steps. The steps may include: The remote WTRU may notify the eNB that the radio bearer may be released. The services of that bearer may be supported via a mobile repeater (e.g., as described herein). The eNB may continue to transmit some or all PDUs over the Uu link until the eNB empties its buffers. The eNB may continue to attempt transmission / retransmission for a period of time. The PDUs may be discarded or transmitted via the mobile repeater WTRU upon expiration of the period of time. The eNB may continue to transmit some or all additional / different packets over the Uu link until the eNB empties its buffers. The eNB may continue to attempt to transmit / retransmit the additional / different packet for a period of time, which may be discarded or transmitted via the mobile repeater WTRU upon expiration of the period of time.

[0249] The remote WTRU may continue to receive data over the bearer until the bearer is released by the eNB or for a specific time period configured in the WTRU. Upon expiration of the time or upon receipt of an RRC reconfiguration by the eNB that releases the bearer, the remote WTRU may delete some or all data associated with the corresponding radio bearer. For example, a timer may be pre-configured in the WTRU or configured by the eNB via RRC signaling.

[0250] A lossless or redundant approach may be used to handle downlink data forwarding from Uu to PC5. For example, the eNB may send some or all PDUs it received that are associated with the old (e.g., on Uu) WTRU address to the WTRU via the Uu link and to the mobile repeater WTRU via the PC5 link. Procedures applicable within the mobile repeater WTRU may be used. The remote WTRU may discard duplicate packets received from both links.

[0251] A lossy approach may be used to handle downlink data forwarding from Uu to PC5. For example, the eNB may discard some or all packets it has buffered, as well as additional and / or different packets destined for the WTRU's old (e.g., on Uu) address. The lossy approach may be simple. The lossy approach may result in data loss as a result of the transition from Uu bearer to PC5 bearer. The lossy approach may include one or more of the following steps.

[0252] The remote WTRU may notify the eNB that a radio bearer may be released. The services of that bearer may be supported via a mobile repeater (e.g., as described herein). The eNB may discard some or all PDCP PDUs of the radio bearer to be released. The eNB may discard additional packets received and addressed to the WTRU and destined for the radio bearer. The remote WTRU may delete some or all data associated with the Uu radio bearer. The remote WTRU may delete some or all data associated with the Uu radio bearer upon receipt of an RRC connection reconfiguration that releases the bearer. The remote WTRU may delete some or all data associated with the Uu radio bearer upon receipt of a data packet over the PC5 link destined for the same application layer entity. The remote WTRU may delete some or all data associated with the Uu radio bearer after sending a notification to the eNB that the radio bearer may be released.

[0253] Several techniques may be used to handle uplink data that the WTRU is sending to the eNB during the transition from Uu to PC5.

[0254] A completely loseless approach may be used to handle uplink data forwarding from Uu to PC5. For example, the WTRU may forward some or all RLC PDUs that were not transmitted or RLC PDUs that were transmitted but not acknowledged from the Uu bearer to a different PC5 bearer. The forwarding of the RLC PDUs may occur (e.g., after establishment of a PC5 connection). In one example, the remote WTRU may create different PC5 logical channels for traffic that is used and sent to the service provided via the mobile repeater. Before sending the different packets over the different PC5 logical channels, the remote WTRU may forward some or all PDCP PDUs that were not transmitted or PDCP PDUs that were transmitted but not acknowledged to the different logical channels. The remote WTRU may also re-perform some or all PDCP operations (e.g., compression, encryption, and / or the like) on the different packets to take into account security parameters applicable to the link.

[0255] A time-based lossless approach may be used to handle uplink data transfer from Uu to PC5. For example, the WTRU may send some or all PDUs that have not yet been transmitted or RLC PDUs that have been transmitted over the Uu radio bearer during a period of time but not acknowledged (e.g., signaled to the WTRU). The remote WTRU may continue to transmit PDUs over the Uu radio bearer upon receipt of an RRC connection reconfiguration that releases the bearer or upon expiration of a timer. After a trigger (e.g., a timer or a released radio bearer), the remote WTRU may discard the untransmitted or unacknowledged PDUs or move them to a different PC5 bearer for transmission.

[0256] A lossy approach may be used to handle uplink data forwarding from Uu to PC5. For example, the WTRU may discard some or all PDUs that have not yet been transmitted or that have been transmitted but not acknowledged (e.g., after establishment of a PC5 connection). The WTRU may discard some or all PDUs that have not been transmitted or that have been transmitted but not acknowledged after transmission of an indication to the eNB that traffic for the bearer may be forwarded via a mobile repeater. The WTRU may discard some or all PDUs that have not been transmitted or that have been transmitted but not acknowledged after receipt of an RRC connection reconfiguration by the eNB that releases the Uu bearer.

[0257] An ongoing service may have certain packets. The packets may be uplink or downlink packets. The packets may be in the mobile repeater and may be delivered to the eNB or WTRU to avoid service interruption or degradation during the transition (e.g., from the mobile repeater connection (PC5) to the Uu connection).

[0258] To handle uplink data, the mobile repeater WTRU may send packets present at the mobile repeater WTRU and PDUs that were sent but not acknowledged (eg, on the Uu link) to the eNB.

[0259] In the example of an uplink transmission, i.e., PC5 to Uu, the mobile repeater WTRU may continue to empty its PDCP transmission buffer until some or all of the data in the mobile repeater WTRU received from the remote WTRU has been transmitted and acknowledged without modification. The mobile repeater WTRU may continue to empty its PDCP transmission buffer until some or all of the data in the mobile repeater WTRU received from the remote WTRU has been transmitted and acknowledged without modification until expiration of an associated timer or retry counter. An application in the network may temporarily receive packets with a source address assigned by the mobile repeater of the remote WTRU. For in-sequence delivery, the eNB may buffer packets received from the WTRU (e.g., the previous remote WTRU) over the Uu connection. For in-sequence delivery, the eNB may wait for an indication from the PDCP entity communicating to the mobile repeater WTRU before forwarding the PDCP data to upper layers over the newly established Uu link radio bearer.

[0260] In the example of uplink transmission, i.e., PC5 to Uu, the mobile repeater WTRU may flush some / all pending data to be transmitted to the eNB. The WTRU (e.g., previously remote) may receive a status report (e.g., PDCP or upper layers) from the eNB after establishment of the Uu radio bearer, reflecting packets or PDUs that are missing at the eNB. The WTRU may start transmitting over the Uu radio bearer to the eNB starting from the missing packets / PDUs reflected in the status report. The WTRU may retransmit a certain number or PDUs that have already been transmitted over the PC5 link. The number of retransmitted PDUs may be configured by the network or statically set in the WTRU.

[0261] In the example of an uplink transmission, i.e., PC5 to Uu, the mobile repeater WTRU may flush some or all pending data to be transmitted to the eNB. The WTRU (e.g., previously remote) may transmit PDCP PDUs that are to be transmitted after the mobile repeater disconnection.

[0262] In an uplink transmission, i.e., PC5 to Uu example, which may be used in connection with one or more of the other approaches discussed herein, the remote WTRU may suspend transmission to the mobile repeater WTRU at some point of the connecting eNB's initiation (e.g., RACH, RRC connection establishment, and / or the like) to avoid transmitting data to the mobile repeater that may be flushed by the mobile repeater WTRU.

[0263] To handle downlink data, the mobile repeater WTRU may send data (e.g., IP packets, pending PDCP PDUs) to the WTRU (e.g., previously remote). The approaches described herein for the uplink may be used to handle downlink data. The roles of the eNB and the remote WTRU may be reversed. The approaches discussed herein may be used for transfer of a link between a mobile repeater and another mobile repeater (e.g., for mobile repeater reselection).

[0264] Service continuity may be maintained for a mobile repeater WTRU handover from one eNB to another. Mobility of the mobile repeater WTRU may be taken into account. The mobile repeater WTRU may move from the control of one eNB to another. The eNB may include information regarding the WTRU's status as a mobile repeater. The eNB may include mobile repeater context information (e.g., D2D resource pool used by the mobile repeater). This information may be transferred from one eNB to another eNB. In a handover procedure, the mobile repeater context of the eNB may be transferred over the X2 interface to another eNB. Information that may be transferred over the X2 interface during a handover of a mobile repeater WTRU may include one or more of an indication that the WTRU performing the handover is acting as a mobile repeater, a resource pool (e.g., including one specific to mobile repeater functionality) used by the mobile repeater WTRU for D2D communications, a number or list of remote WTRUs served by the mobile repeater, and an identification of the services being used by the set of remote WTRUs served by the mobile relay.

[0265] Service continuity may be maintained via a mobile repeater specific broadcast mechanism. A mobile repeater may be permitted to broadcast a specific message to some or all remote WTRUs served by that mobile repeater. The specific broadcast message may be communicated to a certain mobile repeater link. The specific broadcast message may be sent to some or all remote WTRUs connected to the mobile repeater WTRU via an identifier and / or transmitted within the SL-BCH.

[0266] The mobile repeater WTRU may broadcast control information to some or all of the remote WTRUs connected to it by addressing them with some kind of identifier. This identifier may include an L2 ID, an application ID, a ProSe ID, a MAC address, or similar identifier. The AS and / or application layer may use these identifiers to identify information associated with the mobile repeater operation (e.g., control messaging). The identifier may enable the mobile repeater WTRU to broadcast information specific to the remote WTRUs served by the mobile WTRU or a subset or all remote WTRUs served by the repeater WTRU. The mobile repeater WTRU may or may not send unicast messages to all remote WTRUs across a one-to-one communication link. For example, the identifier may enable the mobile repeater WTRU to send the same control message to remote WTRUs that can receive eMBMS broadcast from the mobile repeater WTRU. The remote WTRU may or may not have an actively established one-to-one communication link with the mobile repeater WTRU.

[0267] A broadcast mechanism may be established. The mobile repeater WTRU may send the broadcast address in a discovery message or during mobile establishment. The mobile repeater WTRU may send the broadcast address as part of the payload of the discovery message. The broadcast address may be sent in the discovery message so that the remote WTRU can listen to the broadcast address for control information. The discovery message may be a Model A or Model B discovery message. The broadcast address may be sent during one-to-one mobile repeater establishment. For example, the broadcast address may be sent during authentication and security establishment of an L2 secure link after a direct communication request made by the remote WTRU. The broadcast address may also be pre-configured or derived from a pre-configuration. For example, the WTRU may derive the broadcast address it must listen to based on its location and some specific rules in the WTRU pre-configuration. The broadcast address may also be derived from the mobile repeater WTRU L2 ID. The remote WTRU may determine the broadcast address to listen to based on a certain translation function applied to the L2 address of the mobile repeater WTRU address it is listening to or being served by.

[0268] The remote WTRU may obtain the broadcast address. The remote WTRU may listen for control messages from the mobile repeater WTRU addressed to the broadcast address (e.g., as long as it uses the services of the mobile repeater WTRU). Such control messages may be provided in D2D communication messages or D2D discovery messages. For example, after the one-to-one link is released, the mobile repeater WTRU may continue to listen to the broadcast address for potentially control-related messages sent by the mobile repeater, even when the remote WTRU is listening to eMBMS over the D2D communication transport.

[0269] A broadcast message may be transmitted within one or more dedicated pools reserved to that effect. The particular pools by which a broadcast message may be transmitted are given by dedicated signaling or in the SIB.

[0270] Broadcast messages may be transmitted in the SL-BCH. An IE may be added to the information transmitted on the SL-BCH for WTRUs acting as mobile repeaters. Reserved bits in the MasterInformationBlock-SL may be used to transmit broadcast messages.

[0271] The broadcast message may include one or more of the following information: mobile repeater WTRU identifier (e.g., L2 ID, PHY ID, or other), other mobile repeater identification (e.g., for mobile repeater redirection), TMGI, resource pool configuration for the remote WTRU, and / or actions that may be performed by the remote WTRU. The action may be identified as a code or a few bits in the message, with a set of bits referring to a particular type of action to be performed. The actions may include one or more of initiate mobile / stop repeater reselection, start / stop discovery or measurement, switch to / from Uu connection, direct traffic to / from Uu, pause / start transmission on PC5, reselect to mobile different repeater, and / or reconfiguration of Mode 2 TX / RX pools (e.g., a command to change the utilized RX / TX resource pools).

[0272] Service continuity may be maintained by using a Uu connection and a mobile repeater connection. A remote WTRU may be able to maintain a Uu connection and a mobile repeater connection. For example, a WTRU may receive public safety traffic via a mobile repeater WTRU and may receive non-public safety traffic directly from an eNB on the Uu interface. The mobile repeater WTRU may be connected to the same or a different eNB.

[0273] If a WTRU is being served by an eNB for public safety and non-public safety services and the WTRU may begin to move out of the coverage of the eNB, the WTRU may be moved to a mobile repeater to continue some or all public safety communications. The network may release some or all bearers related to public safety communications on the Uu link after a mobile repeater link with the mobile repeater WTRU is established. The WTRU may maintain a connection to the eNB over the Uu interface to continue to be served by non-public safety related bearers. The eNB may send an indication to the WTRU to trigger the WTRU to select a mobile repeater. The selection may be made by the eNB or the WTRU. The WTRU may perform a connection to the mobile repeater, and a connection to the network may be established via the mobile repeater. After the mobile repeater connection is established, the network may release the public safety related bearers on the Uu link and begin sending public safety related traffic using the mobile repeater (e.g., after reconfiguring the WTRU to use a different address or to use the same address via the mobile repeater). The WTRU may continue to communicate over the Uu interface for non-public safety services and over the PC5 interface for some or all public safety services until the WTRU goes out of coverage. Procedures for loss of coverage of the Uu link may be performed.

[0274] When having simultaneous Uu and PC5 connections, a WTRU may be connected to an eNB via a Uu connection for non-public safety traffic and simultaneously connected to a mobile repeater WTRU for public safety traffic that may be connected to a different eNB. The eNB may or may not be aware of the resources used by the mobile repeater. The eNB may or may not coordinate with the Uu resources used to communicate with the WTRU. The mobile repeater WTRU transmission and synchronization source may or may not be synchronized with the timing of the eNB.

[0275] The WTRU may send to the eNB the identity of the different eNB to which the mobile repeater WTRU is connected. The identity of the different eNB may be obtained by the WTRU via an eCGI announcement. The identity of the different eNB may be sent by the mobile repeater WTRU in a mobile repeater discovery message or may be obtained during connection establishment with the mobile repeater WTRU. Using the identity of the different eNB, the eNB may obtain the timing reference of the mobile repeater WTRU (e.g., timing difference between eNBs) and mobile repeater resource information via X2.

[0276] For example, the WTRU may monitor mobile repeater discovery messages to measure potential mobile repeaters. Based on mobile repeater selection criteria, the WTRU or the serving eNB may select a mobile repeater WTRU served by another eNB. The WTRU may perform an eCGI procedure to determine the eCGI of the eNB serving the mobile repeater WTRU. Before performing connection establishment with the mobile repeater WTRU, the WTRU may send an indication of connection establishment to its serving eNB along with an identification of the other eNB (e.g., the eNB serving the mobile repeater WTRU). The eNB serving the WTRU may obtain timing and resource information utilized by the mobile repeater via X2 communication with the eNB serving the mobile repeater WTRU and may schedule ongoing resources on the Uu interface for non-public safety data communication with the remote WTRU. The eNB may enable the WTRU to proceed with connection establishment with the mobile repeater WTRU.

[0277] Using the identity of the different eNB, the eNB can trigger a handover to the different eNB (e.g., if this is possible). For example, the cell identity of the mobile repeater WTRU to which the WTRU wishes to perform a connection may be sent to the WTRU serving eNB. The eNB can reject or delay the request to initiate the mobile repeater connection until after the handover while initiating / configuring intra / inter frequency measurements in the WTRU and / or initiating a handover of the WTRU to a different eNB.

[0278] A WTRU may send synchronization and resource pool information of a mobile repeater WTRU to its serving eNB. For example, a remote WTRU may monitor mobile repeater discovery messages to measure potential mobile repeaters. Based on mobile repeater selection criteria, the remote WTRU or the serving eNB may select a mobile repeater WTRU served by another eNB. The WTRU may send synchronization reference information (e.g., timing difference of the mobile repeater WTRU's synchronization source from its own serving eNB timing) to the eNB before attempting to establish a connection with the mobile repeater WTRU. The eNB serving the mobile repeater WTRU may use this information to adjust some or all Uu resource allocations (e.g., for non-public safety traffic) made to the WTRU. The WTRU may send this information to the eNB if the mobile repeater WTRU sends a resource reconfiguration to the WTRU at some point during the communication.

[0279] The WTRU may be denied connection to the mobile repeater after sending information about the eNB associated with the mobile repeater, For example, the eNB may send a redirection to the WTRU or may instruct the WTRU to connect to a different mobile repeater using a Uu link.

[0280] The processes described above may be implemented in a computer program, software, and / or firmware embodied in a computer-readable medium for execution by a computer and / or a processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and / or wireless connections) and / or 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, but not limited to, internal hard disks and removable disks, magneto-optical media, and / or optical media such as CD-ROM disks and / or digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, a terminal, a base station, an RNC, and / or any host computer. WTRU-to-network repeater, WTRU-to-network mobile repeater, and / or mobile repeater may be used interchangeably. ProSe mobile repeater and mobile repeater may be used interchangeably in some scenarios.

Claims

1. 1. A method performed by a remote wireless transmit / receive unit (WTRU), comprising: performing measurements on PC5 links associated with one or more repeater WTRUs; determining at least one of the one or more relay WTRUs as a candidate relay WTRU that satisfies upper layer criteria; determining a quality of the candidate repeater WTRU based on the measurements; and transmitting to a radio access network (RAN) node currently serving the remote WTRU the quality, information indicative of an identifier of the candidate repeater WTRU, and information indicative of an identifier of a RAN node associated with the candidate repeater WTRU, the identifier of the candidate repeater WTRU including a repeater Layer 2 (L2) identifier; Including, The method, wherein the transmitting is triggered upon a condition that one or more set criteria are met, the one or more set criteria including a quality of the candidate repeater WTRU being above a threshold for a predetermined period of time.

2. The method of claim 1 , wherein performing the measurements includes measuring signal quality of the one or more repeater WTRUs.

3. The method of claim 1 or 2, wherein the transmitting includes reporting a measured signal quality of the candidate repeater WTRU.

4. The method of claim 1 , wherein the transmitting comprises transmitting the quality directly over a Uu link to the RAN node currently serving the remote WTRU.

5. The method of claim 1 , wherein the transmitting comprises transmitting the quality via the repeater WTRU to the RAN node currently serving the remote WTRU.

6. 6. The method of claim 4 or 5, comprising receiving the one or more configured criteria for determining when a transmission is triggered by the remote WTRU to the RAN node currently serving the remote WTRU.

7. The method of claim 6 , wherein the quality of the candidate repeater WTRU that meets the upper layer criteria is higher than the quality of a current repeater WTRU by an amount greater than a threshold.

8. 1. A wireless transmit / receive unit (WTRU), comprising: Memory, performing measurements on PC5 links associated with one or more repeater WTRUs; determining at least one of the one or more relay WTRUs as a candidate relay WTRU that satisfies upper layer criteria; determining a quality of the candidate repeater WTRU based on the measurements; and A processor configured to execute a transceiver configured to: transmit to a radio access network (RAN) node currently serving the WTRU the quality, information indicative of an identifier of the candidate repeater WTRU, and information indicative of an identifier of a RAN node associated with the candidate repeater WTRU, the identifier of the candidate repeater WTRU including a repeater Layer 2 (L2) identifier; Equipped with The WTRU, wherein the transmitting is triggered upon a condition that one or more set criteria are satisfied, the one or more set criteria including the quality of the candidate relay WTRU being above a threshold for a predetermined period of time.

9. The WTRU of claim 8 , wherein the measurements include measurements of signal quality of the one or more repeater WTRUs.

10. The WTRU of claim 8 or 9, wherein the transceiver is configured to report a measured signal quality of the candidate repeater WTRU.

11. The WTRU of claim 8 , wherein the transceiver is configured to transmit the quality directly over a Uu link to the RAN node currently serving the WTRU.

12. The WTRU of claim 11 , wherein the transceiver is configured to receive the one or more configured criteria for determining when a transmission to the RAN node currently serving the WTRU is triggered.

13. The WTRU of claim 12 , wherein a signal quality of the candidate repeater WTRU that meets the upper layer criteria is higher than the quality of a current repeater WTRU by an amount greater than a threshold.

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