HK1241635B - Discovery and communication using a ue-to-ue relay - Google Patents

Description

Discovery and communication using UE-to-UE relay

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Patent Application No. 14/812,833, filed on July 29, 2015, entitled “PUBLIC SAFETY DISCOVERY AND COMMUNICATION USING A UE-TO-UE RELAY,” which in turn claims priority to U.S. Provisional Patent Application No. 62/103,754, filed on January 15, 2015, entitled “PUBLIC SAFETY DISCOVERY AND COMMUNICATION USING A UE-TO-UE RELAY.” The entire disclosures of each of these, except for those portions, if any, that are inconsistent with this specification, are hereby incorporated by reference in their entireties for all purposes.

Technical Field

Embodiments of the present disclosure generally relate to the field of wireless communications, and more particularly, to an apparatus and method for implementing public safety device-to-device (D2D) functionality.

Background Art

The background description provided here is for the purpose of generally presenting the context of the present disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art or an indication of prior art by inclusion in this section.

D2D applications can provide a scalable and universal framework for connecting neighboring peers. For D2D applications, there are different technical solutions, for example, based on WiFi direct connection or near field communication (NFC) technology. D2D functions related to the Third Generation Partnership Project (3GPP) can also be provided by Proximity Services (ProSe) or Long Term Evolution (LTE) direct connection. In some cases, it may be desirable for members of a group (for example, public safety users) to communicate directly with D2D, i.e., user equipment (UE) to UE. However, the transmitting UE may not always be within the range of the receiving UE.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, similar reference numerals refer to similar structural elements. The embodiments are illustrated in the figures of the accompanying drawings by way of example and not by way of limitation.

FIG1 schematically illustrates a wireless communication system according to various embodiments.

FIG2 is a schematic block diagram illustrating components of an evolved Node B (eNB) and a UE according to various embodiments.

3 is a diagram illustrating an example UE-to-UE relay discovery and communication process using Model A (Announce/Monitor) in accordance with various embodiments.

4 is a diagram illustrating an example UE-to-UE relay discovery and communication process using Model B (discoverer/discovered) in accordance with various embodiments.

5 is a block diagram of an example computing device that may be used to implement various embodiments described herein.

FIG6 illustrates an article of manufacture with programmed instructions incorporating aspects of the present disclosure, according to various embodiments.

DETAILED DESCRIPTION

In the following detailed description, reference will be made to the accompanying drawings, which form a part thereof, wherein like numerals refer to like parts throughout, and in which are shown by way of illustration embodiments that may be implemented. It is to be understood that other embodiments may be utilized and that structural or logical changes may be made without departing from the scope of the present disclosure.

Each operation can be described as a plurality of discrete actions or operations in a manner that is most helpful for understanding the claimed subject matter. However, the order of description should not be regarded as implying that these operations are necessarily sequence-dependent. In particular, these operations may not be performed in the order presented. The described operations may be performed in an order different from that of the described embodiments. In additional embodiments, various additional operations may be performed, and/or the described operations may be omitted.

For purposes of this disclosure, the phrase "A and/or B" means (A), (B), or (A and B). For purposes of this disclosure, the phrase "A, B, and/or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). The description may use the phrases "in one embodiment" or "in an embodiment," which may both refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," and the like, as used with respect to embodiments of the present disclosure, are synonymous.

As used herein, the term "circuitry" may refer to, be part of, or include application specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated, or groups) and/or memories (shared, dedicated, or groups) that execute one or more software or firmware programs, combinational logic circuits, and/or other suitable hardware components that provide the described functionality.

FIG1 schematically illustrates a wireless communication system 100 including public safety discovery and communication using the UE-to-UE relay teachings of the present disclosure, according to various embodiments. The wireless communication system 100 may include a backbone network 110, a cellular mobile network 120, and a D2D network 130. The D2D network 130 may include UEs 132, 134, and 136, which may also communicate using the cellular mobile network 120.

Backbone network 110 may be part of a computer network infrastructure that interconnects various subnets and provides for exchanging information between these subnets. In various embodiments, backbone network 110 may include Internet backbone 112, which may include primary data routing between large strategically interconnected computer networks and core routers on the Internet.

The cellular mobile network 120 can communicate data with the backbone network 110. In various embodiments, the cellular mobile network 120 may include one or more radio access networks (e.g., Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), Universal System for Mobile Communications (UMTS), High Speed Packet Access (HSPA), Evolved HSPA (E-HSPA), or Long Term Evolution (LTE) networks). In some embodiments, the radio access network may include a GSM Enhanced Data Rates for GSM Evolution (EDGE) Radio Access Network (GERAN), a Universal Terrestrial Radio Access Network (UTRAN), or an Evolved UTRAN (E-UTRAN). In other embodiments, the cellular mobile network 120 may operate according to other network technologies.

Mobile communication technology can rely on various standards and protocols to transmit data between base stations and wireless communication devices. Wireless communication system standards and protocols can include, for example: 3GPP LTE; Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, which is often referred to as Worldwide Interoperability for Microwave Access (WiMAX) to industry groups; and IEEE 802.11 standard, which is often referred to as Wi-Fi to industry groups. In a 3GPP radio access network (RAN), according to LTE, a base station can be called an evolved Node B (also commonly denoted as eNodeB or eNB). It can communicate with a wireless communication device called a user equipment (UE). Although the present disclosure is presented with terms and examples generally for 3GPP systems and standards, the teachings disclosed herein can be applied to any type of wireless network or communication standard.

In various embodiments, the cellular mobile network 120 may include an eNB 124, a radio network controller (RNC) and a legacy Node B (NB) 126, a mobility management entity (MME) and a serving gateway (SGW) 122, and a serving GPRS support node (SGSN) 128. The eNB 124 may include more functionality than a legacy NB 126 that may be used in a 3G network (e.g., a UMTS network). For example, the RNC functionality may be located in the eNB 124 rather than in a separate RNC entity. In LTE, the eNB 124 may be connected to another eNB via an X2 interface that allows the eNBs to forward or share information. In some embodiments, the cellular mobile network 120 may be an Internet Protocol (IP)-based network, wherein the interfaces between network entities (e.g., the eNB 124 and the MME/SGW 122) may be IP-based. In some embodiments, the MME/SGW 122 may communicate with the eNB 124 via an S1 interface. The S1 interface may be similar to the S1 interface defined in 3GPP Technical Specification (TS) 36.410 V11.1.0 (2013-09) and may support a many-to-many relationship between MME/SGW 122 and eNB 124. For example, different operators may simultaneously operate the same eNB in a shared network configuration. In some embodiments, communication between eNB 124 and a UE may be facilitated via MME/SGW 122. MME/SGW 122 may be configured to manage signaling exchanges (e.g., authentication of a UE (e.g., UE 132)) or perform other actions associated with establishing a communication link to establish a connected mode for UE 132 with cellular mobile network 120. In some embodiments, MME/SGW 122 may be responsible for tracking and paging the user equipment, for example, when UE 132 is in idle mode.

For ease of illustration, various descriptions herein are provided in the context of communication system 100 in accordance with 3GPP; however, the subject matter of the present disclosure is not limited thereto, and the embodiments disclosed herein may be advantageously applied to other wired or wireless communication protocols or networks. For example, in an embodiment where cellular mobile network 120 includes UTRAN, eNB 124 may represent a radio network controller (RNC) configured to communicate with UE 132, 134, or 136 (discussed in further detail below) via the NB. In an embodiment where cellular mobile network 120 includes GERAN, eNB 124 may represent a base station controller (BSC) configured to communicate with UE 132, 134, or 136 via a base station transport (BTS).

In various embodiments, UE 132 can access cellular mobile network 120 via a radio link with a base station (e.g., eNB 124). Downlink (DL) transmissions can be communications from eNB 124 to UE 132. Uplink (UL) transmissions can be communications from UE 132 to eNB 124. For ease of illustration, only a limited number of UEs and eNBs are shown in FIG1 . However, when implementing suitable embodiments of the present disclosure, communication system 100 can include any number of UEs, eNBs, or other servers. As an example, in some embodiments, cellular mobile network 120 can also include other servers, such as machine type communication (MTC) servers (not shown), to facilitate MTC.

In some embodiments, UE 134 can be configured to communicate with another machine. Data can be sent from UE 134 to another machine, or received by UE 134 from another machine, with little or no human interaction required. For example, UE 134 can be a sensor electrically coupled to a wireless transceiver (e.g., transceiver circuitry 224 discussed below with reference to FIG. 2 ) and can be configured to communicate with another machine (e.g., another sensor) with little or no human interaction. In some embodiments, the wireless transceiver of UE 134 can also be configured to communicate with at least one of a wireless metropolitan area network (WMAN), a wireless local area network (WLAN), or a wireless personal area network (WPAN).

In some embodiments, UE 136 may be a mobile communication device, a subscriber station, or another device configured to communicate with cellular mobile network 120 according to an appropriate protocol (e.g., a multiple-input multiple-output (MIMO) communication scheme), for example, via eNB 124. As discussed in more detail below, UEs 132, 134, and/or 136 may be configured to enable D2D functionality. In embodiments, the D2D functionality may also be referred to as sidelink direct communication (SL).

In various embodiments, UE 132, UE 134, and UE 136 may form a D2D network 130. In D2D network 130, two UEs in close proximity can communicate directly without routing the communication through eNB 124 or any other base stations and cellular mobile networks. Direct communication between devices is often referred to as D2D communication or point-to-point (P2P) communication. In various embodiments, D2D communication may be established directly by the UEs or may be at least partially facilitated by the eNB.

D2D operations in D2D network 130 may be opaque to cellular mobile network 120 and may occur in the cellular spectrum (e.g., in-band) or in the unlicensed spectrum (e.g., out-of-band). D2D operations in D2D network 130 may be implemented using different communication technologies. In some embodiments, short-range technologies (e.g., Bluetooth or Wi-Fi) may be used. In some embodiments, D2D operations may reuse the licensed LTE spectrum or the unlicensed LTE spectrum.

In various embodiments, D2D operations in the D2D network 130 may include device discovery, whereby UEs determine whether they are within range and/or available for D2D operations before establishing a D2D session. Proximity detection may be assisted by the cellular mobile network 120, may be performed at least partially by the UE, or may be performed largely independently by the UE.

In various embodiments, D2D discovery can be either closed D2D discovery or open D2D discovery. Closed D2D discovery can be applied to use cases where only a select set of D2D-enabled discovery devices can discover discoverable devices. For example, only pre-identified or selected devices (e.g., devices identified or selected by the cellular mobile network 120, a D2D server (not shown), an application (not shown), or a user (not shown)) can be allowed to connect. Therefore, for such use cases, it will be assumed that the discovering device has prior knowledge of the D2D-enabled devices it wishes to discover in its vicinity, including any corresponding identifiers.

On the other hand, open device discovery considers use cases where a discoverable device may want to be discovered by any or all D2D-enabled devices in its vicinity. From the perspective of the discovering device, open device discovery implies that the discovering device may not know the identities of other D2D-enabled devices before discovery. Therefore, the device discovery mechanism for open discovery can aim to discover as many D2D-enabled devices in its vicinity as possible.

In some cases, such as for open D2D discovery using authorized resources, the eNB may have limited control over the discovery process between UEs. Specifically, the eNB may periodically allocate certain discovery resources (e.g., time/frequency resources (e.g., resource blocks or subframes)) in the form of D2D discovery zones for UEs to send discovery information. The discovery information may be in the form of discovery sequences or discovery packets with payload information.

In various embodiments, D2D operations in D2D network 130 can improve spectrum utilization, increase network throughput, reduce transmission delays, offload traffic from eNB 124, and alleviate congestion in cellular mobile network 120. In this regard, D2D operations can have a wide variety of applications. For example, D2D network 130 can be used for local social networking, content sharing, location-based marketing, service advertising, mobile-to-mobile applications, and the like. In embodiments, D2D network 130 can serve as a fallback public safety network, capable of operating even when cellular mobile network 120 becomes unavailable or fails.

In various embodiments, some UEs in D2D network 130 may be positioned relative to other UEs in D2D network 130 such that they can communicate with some UEs but not others. In an embodiment, although UE 132, UE 134, and UE 136 may all be members of a common safety group, UE 134 may be located at a distance from UE 136 such that UE 134 and UE 136 cannot communicate directly with each other using a D2D sidelink. However, each of UE 134 and UE 136 may be able to communicate with UE 132 using D2D communication, such that UE 132 may act as a UE relay for D2D communication between UE 134 and UE 136 using UE 132 as a relay UE.

FIG2 is a schematic block diagram illustrating components of an eNB 210 and a UE 220 in a wireless communication environment, including public safety discovery and communication using the UE-to-UE relay teachings of the present disclosure, according to various embodiments. The eNB 210 may be similar to and substantially interchangeable with the eNB 124 of FIG1 . In embodiments, the eNB 210 may include one or more antennas 218 and a communications module 212 . In various embodiments, the transceiver circuitry 214 , radio control circuitry 215 , and processing circuitry 216 within the communications module 212 may be coupled to one another as shown. Similarly, the UE 220 may be similar to and substantially interchangeable with the UEs 132 , 134 , or 136 of FIG1 . In embodiments, the UE 220 may include one or more antennas 228 and a communications module 222 . In various embodiments, the transceiver circuitry 224 , radio control circuitry 225 , and processing circuitry 226 within the communications module 222 may be coupled to one another as shown.

The transceiver circuitry 214 may be coupled to an antenna 218 to facilitate over-the-air communication of signals to and from the eNB 210. Operations of the transceiver circuitry 214 may include, but are not limited to, filtering, amplification, storage, switching, and the like. In various embodiments, the transceiver circuitry 214 may be configured to provide various signal processing operations on signals to the antenna 218 having appropriate characteristics. In some embodiments, the transceiver circuitry 214 may be configured to communicate with a UE capable of D2D operation. The transceiver circuitry 214 may be configured to receive signals from the antenna 218 for transmission to other components of the eNB 210 and/or for internal processing by the processing circuitry 216.

Processing circuitry 216 may generate configuration and control information for a UE (e.g., UE 220) in a serving cell, and may generate signals for transmitting the configuration and control information to the UE via transceiver circuitry 214. The configuration and control information may include, for example, downlink channel information, downlink control information (DCI), radio resource control (RRC) configuration information, and the like. In some embodiments, such configuration and control information may include a SIB message for activating at least one of D2D discovery, D2D communication, or D2D relay functionality for UE 220. In various embodiments, processing circuitry 216 may generate different types of SIB messages for UE 220. As an example, processing circuitry 216 may generate a first type of SIB message for primary notification, followed by a second type of SIB message for secondary notification containing authentication or configuration information regarding D2D operations. In various embodiments, the secondary notification to UE 220 may include information regarding a preferred spectrum for D2D operations, information regarding D2D synchronization source settings, a public safety alert, or a public safety release message.

In various embodiments, the processing circuit 216 may generate the aforementioned SIB message for a large number of selected UEs in the warning area, for example, to construct the D2D network 130 of FIG. 1 . In some embodiments, the communication module 212 may send a first type of SIB message with a primary notification via paging. Paging messages may be used to communicate with UEs in RRC_IDLE mode and RRC_CONNECTED mode. In some embodiments, the communication module 212 may send a second type of SIB message with a secondary notification via a cell broadcast service (CBS).

Similar to the communication module 212, the communication module 222 can be coupled to the antenna 228 to facilitate over-the-air communication of signals between the UE 220 and the eNB 210 or between the UE 220 and another UE. For example, the transceiver circuit 224 can be configured to provide various signal processing operations on the signals to the antenna 228 having appropriate characteristics. In various embodiments, the operations of the transceiver circuit 224 can include, but are not limited to, filtering, amplification, storage, switching, etc. The transceiver circuit 224 can be configured to receive signals from the antenna 218 and then transmit the signals to other components of the UE 220 and/or for internal processing by the processing circuit 226.

In some embodiments, the communication module 222 may be configured to receive a primary notification in a paging type 1 message if the UE 220 is in an RRC_IDLE state. In some embodiments, the communication module 222 may be configured to receive a primary notification in a system information change indication (SICI) message if the UE is in an RRC_CONNECTED state. In some embodiments, the processing circuit 226 may configure the communication module 222 to receive one or more cell broadcast messages containing one or more secondary notifications with authentication or configuration information regarding D2D operations in response to the primary notification. In some embodiments, the communication module 222 may receive the one or more cell broadcast messages and, based at least in part on the information contained in the secondary notifications, the UE 220 may be properly configured for D2D operations, such as with a spectrum preferred for D2D operations or a correct D2D synchronization source.

In some embodiments, UE 220 may include one or more antennas 228 for simultaneously utilizing the radio resources of multiple component carriers. UE 220 may be configured to communicate using orthogonal frequency division multiple access (OFDMA) (e.g., in downlink communications) and/or single carrier frequency division multiple access (SC-FDMA) (e.g., in uplink communications). In some embodiments, UE 220 may use transceiver circuitry 224 to communicate with another UE via LTE ProSe or LTE Direct.

In some embodiments, the communication module 222 may be configured to provide communication services to one or more subscriber identity modules (SIMs) (not shown) to which it may be coupled. In some embodiments, the SIM may be removably coupled to the communication module 222. In other embodiments, the SIM may be hardware and/or firmware permanently coupled to the UE 220. In various embodiments, the SIM may include a universal integrated circuit card (UICC), a full-size SIM, a mini SIM, a micro SIM, a nano SIM, an embedded SIM, and/or a virtual SIM. In some embodiments, one or more SIMs may store upper-layer user information, which may be sent by a UE coupled to the SIM to other UEs in a communication message.

A SIM card may be an integrated circuit that securely stores subscriber identity information (e.g., an International Mobile Subscriber Identity (IMSI)) and related keys for identifying and authenticating one or more subscribers using the UE 220. Each SIM card may be associated with different subscriber identity information and/or other user information and may or may not be associated with different operators. In various embodiments, the IMSI and related information may be used to facilitate D2D discovery and D2D operations.

Some or all of the transceiver circuitry 224 and/or the processing circuitry 226 may be included in, for example, radio frequency (RF) circuitry or baseband circuitry as described below with respect to FIG5. In various embodiments, the UE 220 may be, include, or be included in a single sensor device, a cellular phone, a personal computer (PC), a notebook, an ultrabook, a netbook, a smartphone, an ultra mobile PC (UMPC), a handheld mobile device, a UICC, a personal digital assistant (PDA), a consumer premises equipment (CPE), a tablet computing device, or other consumer electronic device (e.g., an MP3 player, a digital camera, etc.). In some embodiments, the UE may include a mobile station defined by IEEE 802.16e (2005 or 802.16m (2009)) or some other amendment to the IEEE 802.16 standard, or a user equipment defined by 3GPP LTE Release 8 (2008), Release 9 (2009), Release 10 (2011), Release 12 (2014), Release 13 (under development), or some other amendment or release of the 3GPP LTE standard.

FIG3 is a diagram illustrating an example UE-to-UE relay discovery and communication process 300 using Model A (announcement/monitoring). In an embodiment, UE 302, UE 304, and UE 306 may each perform group member discovery using Model A or Model B (discoverer/discoveree) before performing UE-to-UE relay discovery using Model A. In various embodiments, UEs 302, 304, and 306 may be similar to, and substantially interchangeable with, UEs 132, 134, and 136 of FIG1, respectively. UEs 302, 304, and 306 may be configured as described with respect to UE 220 of FIG2. In some embodiments, group member discovery using Model A or Model B may be performed using the methods described in 3GPP Technical Report (TR) 23.713 (Release 13, Version 0.3.0, 2014) and/or may be implemented using the D2D discovery or D2D communication capabilities described in 3GPP Technical Specification (TS) 36.300 (Release 12, Version 12.4.0, 2014). In the case of Model A group member discovery, each UE may act as an announcing UE to send a message with the following parameters: a Type parameter set to Announcement, a Discovery Type parameter set to Group Member Discovery, an Announcer Information parameter set to include upper layer information related to a user associated with the announcing UE (e.g., IMSI, Mobile Subscriber Identity Number (MSIN), or other information that may be stored on a UICC in the announcing UE), and a ProSe UE ID parameter set to the ProSe UE ID of the announcing UE. In some embodiments, the ProSe UE ID may be a link layer identifier for direct communication. In various embodiments, the announcing UE may periodically broadcast the announcement message. If another UE acting as a monitoring UE receives a message from the announcing UE, it may determine that it can participate in D2D communication with the announcing UE.

In the case of Model B group member discovery, each UE may act as a discoverer UE and send a message with the following parameters: a Type parameter set to Request, a Discovery Type parameter set to Group Member Discovery, a Discoverer Information parameter set to include upper layer discoverer information related to one or more users associated with other UEs in the discoverer UE group, a Discoverer Information parameter set to include upper layer discoverer information related to the user associated with the discoverer UE, and a ProSe UE ID parameter set to the ProSe UE ID of the discoverer UE. In various embodiments, the discoverer UE may broadcast, multicast, or groupcast the request message. If another UE acting as a discoverer UE receives the request message from the discoverer UE and determines that it is associated with one of the UEs associated with the discoverer information, it may send a response message back to the discoverer UE with the following parameters: a Type parameter set to Response, a Discovery Type parameter set to Group Member Discovery, a Discoverer Information parameter set to include upper layer discoverer information related to the user of the UE sending the response message, and a ProSe UE ID parameter set to the ProSe UE ID of the discoverer UE sending the response message. In some embodiments, the response message may be unicast.If a UE acting as a discoverer UE receives a response message from a UE acting as a discoveree UE, the discoverer UE may determine that it can participate in D2D communication with the discoveree UE that sent the response message.

In various embodiments, UE 304 may discover UE 306 at block 308 through group member discovery using either Model A or Model B. At block 310, UE 302 may discover both UE 304 and UE 306 through group member discovery using either Model A or Model B. Upon discovering both UE 304 and UE 306, UE 302 may determine that it can serve as a potential relay UE between UE 304 and UE 306. In various embodiments, UEs 302, 304, and 306 may all be configured as part of a public safety group. In some embodiments, UE 302 may not be part of a public safety group and may participate in a UE discovery process at block 310. This UE discovery process allows UE 302 to discover UE 304 and UE 306 even if UE 302 is not part of the public safety group, allowing UE 304 and UE 306 to use UE 302 as a UE relay for D2D communications even if UE 302 is not a member of the group.

As part of UE-to-UE relay discovery under Model A (Announcement/Monitoring), UE 302 may send an announce message at block 312. The announce message may include a Type parameter set to Announcement, a Discovery Type parameter set to UE-to-UE Relay Discovery, an Announcer Information parameter set to include upper layer information related to a user associated with UE 302 (e.g., IMSI, MSIN, or other information that may be stored on a UICC in UE 302), a ProSe UE ID parameter set to the ProSe UE ID of UE 302, and a list of upper layer remote user information parameters related to users associated with the discovered UE 304 and the discovered UE 306. In some embodiments, the announce message may also include layer 2 identifiers of the discovered UE 304 and the discovered UE 306. The layer 2 identifiers may be MAC addresses in some embodiments and may be provided in association with the list of upper layer remote user information parameters in various embodiments. As both UE 304 and UE 306 monitor for the announce message, they may receive the announce message.

UE 304 may then communicate with UE 306 using UE-to-UE relay in a D2D communication process 316 having a first communication 318 to UE 302 that is relayed by UE 302 to UE 306 in a second communication 320. In some embodiments, D2D communication process 316 may be performed in a push-to-talk manner.

In various embodiments, an extended MAC header may be used that includes a relay layer 2 ID parameter for identifying a UE-to-UE relay and a field for a direction parameter indicating whether the MAC frame is being sent "to the relay" or "from the relay." When UE 304 sends data to UE 306 via UE 302 in a first communication 318, the addressing identifier in the MAC frame may be set with the following fields: Source Layer 2 ID = ProSe UE ID (e.g., Layer 2 ID) of UE 304; Destination Layer 2 ID = ProSe UE ID (e.g., Layer 2 ID) of UE 306; Relay Layer 2 ID = ProSe UE ID (e.g., Layer 2 ID) of UE 302; and Direction = "to relay."

When UE 302 forwards the MAC frame to UE 306 in the second communication 320 by generating a relay MAC frame based at least in part on the MAC frame received from UE 304, the addressing identifier in the MAC frame may be set with the following fields: Source Layer 2 ID = ProSe UE ID of UE 304 (e.g., Layer 2 ID); Destination Layer 2 ID = ProSe UE ID of UE 306 (e.g., Layer 2 ID); Relay Layer 2 ID = ProSe UE ID of UE 302 (e.g., Layer 2 ID); and Direction = "Self-Relay". In an embodiment, communication between UE 304 and UE 306 may be performed in a stateless manner. In various embodiments, UE 304 may dynamically switch relay UEs on a frame-by-frame basis when communicating with UE 306, which may increase performance by reducing packet flooding. UE 304 may find another potential relay UE and, if UE 302 moves out of range such that it can no longer serve as a relay UE for communications between UE 304 and UE 306, UE 304 may hand over communications to the other potential relay UE.

In some embodiments, the UE-to-UE relay discovery and communication process 300 may include the transfer of Internet Protocol (IP) address information corresponding to UEs 302, 304, and 306, and UE 302 may provide layer 3 rather than layer 2 forwarding. The group member discovery process at blocks 308 and 310 may be enhanced so that each message includes the assigned IP address of the UE sending the message, for example, by including the IP address after the UE's ProSe UE ID in the Group A Announcement message or the Group B Request and Response messages. Another method of transferring the IP address may be used in some embodiments by using additional signaling messages that allow an interested UE (e.g., UE 304) to seek additional information from a relay UE (e.g., UE 302), which in turn may seek information from a remote UE (e.g., UE 306), wherein the IP address information is transferred from the remote UE back to the interested UE via the relay UE.

FIG4 is a diagram illustrating an example UE-to-UE relay discovery and communication process 400 using Model B. In an embodiment, prior to performing UE-to-UE relay discovery using Model B, UE 402, UE 404, and UE 406 may each perform group member discovery using Model A or Model B, as discussed above with respect to UEs 302, 304, and 306 in FIG3 . In various embodiments, UEs 402, 404, and 406 may be located in an LTE network in a manner similar to that described for UEs 132, 134, and 136, respectively, of FIG1 . UEs 402, 404, and 406 may be configured as described with respect to UE 220 of FIG2 . In various embodiments, UE 404 may discover UE 402 at block 408 through group member discovery using Model A or Model B. At block 410, UE 402 may discover UEs 404 and 406 through group member discovery using Model A or Model B. In various embodiments, UEs 402, 404, and 406 may all be configured as part of a public safety group. In some embodiments, UE 402 may not be part of a public safety group and may participate in a UE discovery process at block 410. This UE discovery process allows UE 402 to discover UE 404 and UE 406 even if UE 402 is not part of a public safety group, so that UE 404 and UE 406 can use UE 402 as a UE relay for D2D communications even if UE 402 is not a member of the group. UE 404 may determine that a group member of interest (e.g., a remote user, UE 406) is not within direct range if its neighboring UEs have already been discovered.

Then, as part of UE-to-UE relay discovery under Model B (discoverer/discoveree), UE 404 may request potential UE-to-UE relays in the role of discoverer by sending a request message in block 412. The request message may include a type parameter set to request, a discovery type parameter set to UE-to-UE relay discovery, a discoverer information parameter that may include upper layer user information associated with UE 404 (e.g., IMSI, MSIN, or other information that may be stored on a UICC in UE 404), a ProSe UE ID parameter that may be set to the ProSe UE ID of UE 404 (e.g., a layer 2 identifier of UE 404), and a list of upper layer remote user information parameters for UEs of interest (e.g., user information about users associated with UE 406). In some embodiments, in addition to or in lieu of the list of upper layer remote user information parameters for UEs of interest, the request message may also include a layer 2 identifier for a remote UE of interest. In some embodiments, one or more of the upper layer remote user information parameters may be referred to as target information parameters.

After receiving the request message, UE 402 (in the role of a discoverer) may determine that it is capable of acting as a UE-to-UE relay and may respond with a response message to UE 404. The response message may include a Type parameter set to Response, a Discovery Type parameter set to UE-to-UE Relay Discovery, a Discoverer Information parameter that may include upper-layer discoverer user information (which may be associated with a user of UE 402), a ProSe UE ID parameter that may be set to the ProSe UE ID of UE 402 (e.g., a layer 2 identifier of UE 402), and a list of upper-layer user information parameters related to the user associated with the UE of interest (e.g., user information associated with UE 406). In some embodiments, the response message may also include a layer 2 identifier associated with the UE of interest and may be provided in association with the corresponding upper-layer user information.

After receiving the response message, UE 404 may then communicate with UE 406 using UE-to-UE relay in a D2D communication process 417 having a first communication 418 to UE 402, which is relayed by UE 402 to UE 406 in a second communication 420. In some embodiments, D2D communication process 417 may be performed in a push-to-talk manner.

In various embodiments, an extended MAC header may be used that includes a relay layer 2 ID parameter for identifying a UE-to-UE relay and a field for a direction parameter indicating whether the MAC frame is being sent "to the relay" or "from the relay." When UE 404 sends data to UE 406 via UE 402 in a first communication 418, the addressing identifier in the MAC frame may be set with the following fields: Source Layer 2 ID = ProSe UE ID (e.g., Layer 2 ID) of UE 404; Destination Layer 2 ID = ProSe UE ID (e.g., Layer 2 ID) of UE 406; Relay Layer 2 ID = ProSe UE ID (e.g., Layer 2 ID) of UE 402; and Direction = "to relay."

When UE 402 forwards the MAC frame to UE 406 in the second communication 420 by generating a relay MAC frame based at least in part on the MAC frame received from UE 404, the addressing identifier in the relay MAC frame may be set with the following fields: Source Layer 2 ID = ProSe UE ID of UE 404 (e.g., Layer 2 ID); Destination Layer 2 ID = ProSe UE ID of UE 406 (e.g., Layer 2 ID); Relay Layer 2 ID = ProSe UE ID of UE 402 (e.g., Layer 2 ID); and Direction = "Self-Relay". In an embodiment, communication between UE 404 and UE 406 may be performed in a stateless manner. In various embodiments, UE 404 may dynamically switch relay UEs on a frame-by-frame basis when communicating with UE 406, which may increase performance by reducing packet flooding. UE 404 may find another potential relay UE and, if UE 402 moves out of range such that it can no longer serve as a relay UE for communications between UE 404 and UE 406, UE 404 may hand over communications to the other potential relay UE.

In some embodiments, the UE-to-UE relay discovery and communication process 400 may include the transfer of IP address information corresponding to UEs 402, 404, and 406, and UE 402 may provide layer 3 rather than layer 2 forwarding. The group member discovery process at blocks 408 and 410 may be enhanced so that each message includes the assigned IP address of the UE sending the message, for example, by including the IP address after the UE's ProSe UE ID in the Group A Announcement message or the Group B Request and Response messages. Another method for transferring IP addresses may be used in some embodiments by using additional signaling messages that allow an interested UE (e.g., UE 404) to seek additional information from a relay UE (e.g., UE 402), which in turn may seek information from a remote UE (e.g., UE 406), wherein the IP address information is transferred from the remote UE back to the interested UE via the relay UE.

The UE 220 or eNB 210 described in conjunction with FIG2 can be implemented into a system using any suitable hardware, firmware, and/or software depending on the desired configuration. FIG5 shows an example system 500 for one embodiment, which includes radio frequency (RF) circuitry 504, baseband circuitry 508, application circuitry 512, memory/storage 516, display 520, camera 524, sensor 528, and input/output (I/O) interface 532, which are coupled to each other at least as shown.

Application circuitry 512 may include, for example, but not limited to, one or more single-core or multi-core processors. The processors may include any combination of general-purpose processors and specialized processors (e.g., graphics processors, application processors, etc.). The processors may be coupled to memory/storage 516 and configured to execute instructions stored in memory/storage 516 to enable various applications and/or operating systems running on system 500.

The baseband circuitry 508 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor may include a baseband processor. In various embodiments, the baseband circuitry 508 may include one or more digital signal processors (DSPs). The baseband circuitry 508 may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 504. Radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency offset, etc. In some embodiments, the baseband circuitry 508 may provide communications compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 508 may support communications with E-UTRAN and/or other WMANs, WLANs, or WPANs. Embodiments in which the baseband circuitry 508 is configured to support radio communications using more than one wireless protocol may be referred to as multimode baseband circuitry.

In various embodiments, baseband circuitry 508 may include circuitry that operates with signals that are not strictly considered to be at baseband frequencies. For example, in some embodiments, baseband circuitry 508 may include circuitry that operates with signals having an intermediate frequency between baseband frequencies and radio frequencies.

In some embodiments, processing circuitry 216 or 226 of FIG2 may be embodied in application circuitry 512 and/or baseband circuitry 508. In an embodiment, radio control circuitry 215 or 225 of FIG2 may be embodied in baseband circuitry 508.

RF circuitry 504 may enable communication with a wireless network using modulated electromagnetic radiation over a non-solid medium. In various embodiments, RF circuitry 504 may include switches, filters, amplifiers, etc. to facilitate communication with a wireless network.

In various embodiments, RF circuitry 504 may include circuitry that operates with signals that are not strictly considered to be at radio frequencies. For example, in some embodiments, RF circuitry 504 may include circuitry that operates with signals having an intermediate frequency between baseband and radio frequencies.

In some embodiments, transceiver circuitry 214 or 224 of FIG. 2 may be embodied in RF circuitry 504. In some embodiments, radio control circuitry 215 or 225 of FIG. 2 may be embodied in RF circuitry 504.

In some embodiments, some or all of the constituent components of baseband circuitry 508 , application circuitry 512 , and/or memory/storage 516 may be implemented together on a system on a chip (SOC).

Memory/storage 516 may be used, for example, to load and store data and/or instructions for system 500. Memory/storage 516 for one embodiment may include any combination of suitable volatile memory (e.g., dynamic random access memory (DRAM)) and/or non-volatile memory (e.g., flash memory).

In various embodiments, the I/O interface 532 may include one or more user interfaces that enable a user to interact with the system 500 and/or peripheral component interfaces that enable peripheral components to interact with the system 500. The user interface may include, but is not limited to, a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. The peripheral component interface may include, but is not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power interface.

In various embodiments, the sensors 528 may include one or more sensing devices for determining environmental conditions and/or location information related to the system 500. In some embodiments, the sensors may include, but are not limited to, a gyroscope sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of or interact with the baseband circuitry 508 and/or the RF circuitry 504 to communicate with components of a positioning network (e.g., global positioning system (GPS) satellites).

In various embodiments, the display 520 may include a display such as a liquid crystal display, a touch screen display, etc. In some embodiments, the camera 524 may include a plurality of molded aspheric lenses fabricated with varying dispersion indices and refractive indices. In some embodiments, the camera 524 may include two or more lenses for capturing three-dimensional images for stereoscopic photography.

In various embodiments, the system 500 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In various embodiments, the system 500 may have more or fewer components, and/or a different architecture.

FIG6 illustrates an article of manufacture 610 having programming instructions according to various embodiments, including various aspects of the present disclosure. In various embodiments, the article of manufacture may be used to implement various embodiments of the present disclosure. As shown, the article of manufacture 610 may include a computer-readable non-transient storage medium 620, wherein instructions 630 may be configured to implement an embodiment of any one of the processes described herein or aspects of the embodiments. The storage medium 620 may represent a wide range of permanent storage media known in the art, including but not limited to flash memory, dynamic random access memory, static random access memory, optical disks, magnetic disks, etc. In an embodiment, the computer-readable storage medium 620 may include one or more computer-readable non-transient storage media. In other embodiments, the computer-readable storage medium 620 may be transient, such as a signal encoded with instructions 630.

In various embodiments, the instructions 630 may, in response to being executed by a device, enable the device to perform various operations described herein. As an example, the storage medium 620 may include the following instructions 630, which are configured to cause the device (e.g., UE 220 related to FIG. 2) to implement some aspects of public safety UE-to-UE relay discovery and/or communication according to an embodiment of the present disclosure (e.g., as shown in the UE-to-UE relay discovery and communication process 300 of FIG. 3 or the UE-to-UE relay discovery and communication process 400 of FIG. 4).

The following paragraphs describe examples of various embodiments.

Example 1 may include an apparatus for wireless communication, comprising: one or more storage media having instructions; and a processing circuit coupled to the one or more storage media to execute the instructions, thereby: determining a list of user equipment (UE) with which the apparatus can communicate using device-to-device (D2D) communication; generating a declaration message indicating that the apparatus is capable of acting as a relay based at least in part on the list; and generating a signal based at least in part on the declaration message and controlling a transceiver circuit to send the signal.

Example 2 may include the subject matter of Example 1, wherein the announcement message includes a list of UEs within D2D communication range.

Example 3 may include the subject matter of Example 2, wherein the announce message includes a layer 2 identifier and a user information parameter associated with each UE in the list.

Example 4 may include the subject matter of any of Examples 2-3, wherein the processing circuit is further configured to generate the relay frame based at least in part on a frame received from a UE in the UE list.

Example 5 may include the subject matter of Example 4, wherein the frame received from the UE includes a source layer 2 ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "to relay."

Example 6 may include the subject matter of Example 4, wherein the relay frame comprises a source layer 2 ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "self-relay."

Example 7 may include a user equipment (UE) comprising: one or more storage media having instructions; and a processing circuit coupled to the one or more storage media to execute the instructions, thereby: determining a list of other UEs with which the UE can communicate using device-to-device (D2D) communication; generating a message having a discovery type parameter set to UE-to-UE relay discovery and a parameter corresponding to another UE with which the UE can communicate using D2D communication; and generating a signal based at least in part on the message and controlling a transceiver circuit to send the signal.

Example 8 may include the subject matter of Example 7, wherein the message is an announce message.

Example 9 may include the subject matter of Example 7, wherein the message is a response message generated in response to a request message received from a sending UE, the sending UE being one of the other UEs with which the UE can communicate using D2D communication.

Example 10 may include the subject matter of Example 9, wherein the response message includes a remote user information parameter.

Example 11 may include the subject matter of Example 10, wherein the response message includes a remote UE layer 2 identifier associated with the remote user information parameter.

Example 12 may include the subject matter of Example 11, wherein the remote UE layer 2 identifier is associated with a UE in a list of other UEs with which the UE can communicate using D2D communication, and the response message further includes the layer 2 identifier of the UE.

Example 13 may include the subject matter of any of Examples 7-12, wherein the processing circuit is further used to: generate a relay frame based at least in part on a frame received from a transmitting UE, wherein the transmitting UE is in a list of other UEs with which the UE can communicate using D2D communication.

Example 14 may include at least one computer-readable medium comprising instructions stored thereon, which, in response to execution of the instructions by one or more processors of a user equipment (UE), cause the UE to: perform group member discovery to discover at least one other UE with which the UE can communicate using device-to-device (D2D) communication; and discover a potential relay UE for communicating with a remote UE, wherein the potential relay UE is one of the at least one other UE.

Example 15 may include the subject matter of Example 14, wherein the UE is caused to discover the potential relay UE based at least in part on receiving an announce message from the potential relay UE.

Example 16 may include the subject matter of Example 15, wherein the announce message includes an identifier corresponding to the potential relay UE and a remote user information parameter.

Example 17 may include the subject matter of Example 14, wherein the UE is further caused to send a request message, and the UE is caused to discover the potential relay UE based at least in part on receiving a response to the request message from the potential relay UE.

Example 18 may include the subject matter of Example 17, wherein the request message includes an identifier corresponding to the UE and a remote user information parameter.

Example 19 may include the subject matter of any of Examples 17-18, wherein the request message includes a plurality of remote user information parameters.

Example 20 may include the subject matter of any of Examples 17-19, wherein the request message includes a discovery type parameter set to UE-to-UE relay discovery.

Example 21 may include the subject matter of any of Examples 14-20, wherein the UE is further for: sending a device-to-device MAC frame to the potential relay UE, wherein the MAC frame includes a header with a direction field set to "to relay".

Example 22 may include at least one computer-readable medium including instructions stored thereon, which, in response to execution of the instructions by one or more processors of a user equipment (UE), cause the UE to: perform group member discovery to discover multiple other UEs with which the UE can communicate using device-to-device (D2D) communication; and act as a relay UE for communications between a sending UE and a remote UE, wherein the sending UE and the remote UE are part of the discovered multiple other UEs.

Example 23 may include the subject matter of Example 22, wherein the UE acts as a relay UE by performing layer 2 forwarding.

Example 24 may include the subject matter of any of Examples 22-23, wherein the UE is further caused to send a declaration message, the declaration message including a discovery type parameter set to UE-to-UE relay discovery, wherein the UE acts as a relay UE after sending the declaration message upon receiving an extended MAC header from the sending UE, the extended MAC header including a direction parameter indicating that the MAC frame is being sent to the relay.

Example 25 may include the subject matter of any of Examples 22-24, wherein the UE is further caused to send a response message in response to receiving a request message from another UE, the request message including a remote user information parameter corresponding to a user associated with one of the multiple other UEs discovered, wherein the UE acts as a relay UE after sending the response message upon receiving an extended MAC header from the sending UE, the extended MAC header including a direction parameter indicating that the MAC frame is being sent to the relay.

Example 26 may include a method of wireless communication, comprising: determining a list of user equipment (UE) with which a device can communicate using device-to-device (D2D) communication; generating a declaration message indicating that the device is capable of acting as a relay based at least in part on the list; generating a signal based at least in part on the declaration message; and controlling a transceiver circuit to send the signal.

Example 27 may include the subject matter of Example 26, wherein the announce message includes a list of UEs within D2D communication range.

Example 28 may include the subject matter of Example 27, wherein the announce message includes a layer 2 identifier and a user information parameter associated with each UE in the list.

Example 29 may include the subject matter of any of Examples 27-28, further comprising generating a relay frame based at least in part on a frame received from a UE in the UE list.

Example 30 may include the subject matter of Example 29, wherein the frame received from the UE includes a source layer 2 ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "to relay."

Example 31 may include the subject matter of Example 29, wherein the relay frame comprises a source layer 2 ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "self-relay".

Example 32 may include a method for communicating with a user equipment (UE), comprising: determining a list of other UEs with which the UE can communicate using device-to-device (D2D) communication; generating a message having a discovery type parameter set to UE-to-UE relay discovery and a parameter corresponding to another UE with which the UE can communicate using D2D communication; generating a signal based at least in part on the message; and controlling a transceiver circuit to send the signal.

Example 33 may include the subject matter of Example 32, wherein the message is an announce message.

Example 34 may include the subject matter of Example 32, wherein the message is a response message generated in response to a request message received from a sending UE, the sending UE being one of the other UEs with which the UE can communicate using D2D communication.

Example 35 may include the subject matter of Example 34, wherein the response message includes a remote user information parameter.

Example 36 may include the subject matter of Example 35, wherein the response message includes a remote UE layer 2 identifier associated with the remote user information parameter.

Example 37 may include the subject matter of Example 36, wherein the remote UE layer 2 identifier is associated with a UE in a list of other UEs with which the UE can communicate using D2D communication, and the response message further includes the layer 2 identifier of the UE.

Example 38 may include the subject matter of any of Examples 32-37, further comprising generating a relay frame based at least in part on a frame received from a transmitting UE, wherein the transmitting UE is in a list of other UEs with which the UE can communicate using D2D communication.

Example 39 may include a method of wireless communication, comprising: performing group member discovery to discover at least one other UE with which the UE can communicate using device-to-device (D2D) communication; and discovering a potential relay UE for communicating with the remote UE, wherein the potential relay UE is one of the at least one other UE.

Example 40 may include the subject matter of Example 39, wherein discovering the potential relay UE is based at least in part on receiving an announce message from the potential relay UE.

Example 41 may include the subject matter of Example 40, wherein the announce message includes an identifier corresponding to the potential relay UE and a remote user information parameter.

Example 42 may include the subject matter of Example 39, further comprising sending a request message, wherein discovering the potential relay UE is based at least in part on receiving a response to the request message from the potential relay UE.

Example 43 may include an apparatus for wireless communication, comprising: a unit for determining a list of user equipment (UE) with which the apparatus can communicate using device-to-device (D2D) communication; a unit for generating a declaration message indicating that the apparatus is capable of acting as a relay based at least in part on the list; a unit for generating a signal based at least in part on the declaration message; and a unit for controlling a transceiver circuit to send the signal.

Example 44 may include the subject matter of Example 43, wherein the announcement message includes a list of UEs within D2D communication range.

Example 45 may include the subject matter of Example 44, wherein the announce message includes a layer 2 identifier and a user information parameter associated with each UE in the list.

Example 46 may include the subject matter of any of Examples 44-45, further comprising means for generating a relay frame based at least in part on a frame received from a UE in the UE list.

Example 47 may include the subject matter of Example 46, wherein the frame received from the UE includes a source layer 2 ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "to relay."

Example 48 may include the subject matter of Example 46, wherein the relay frame comprises a source layer 2 ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "self-relay."

Example 49 may include a user equipment (UE) comprising: a unit for determining a list of other UEs with which the UE can communicate using device-to-device (D2D) communication; a unit for generating a message having a discovery type parameter set to UE-to-UE relay discovery and a parameter corresponding to another UE with which the UE can communicate using D2D communication; a unit for generating a signal based at least in part on the message; and a unit for controlling a transceiver circuit to send the signal.

Example 50 may include the subject matter of Example 49, wherein the message is an announce message.

Example 51 may include the subject matter of Example 49, wherein the message is a response message generated in response to a request message received from a sending UE, the sending UE being one of the other UEs with which the UE can communicate using D2D communication.

Example 52 may include the subject matter of Example 51, wherein the response message includes a remote user information parameter.

Example 53 may include the subject matter of Example 52, wherein the response message includes a remote UE layer 2 identifier associated with the remote user information parameter.

Example 54 may include the subject matter of Example 53, wherein the remote UE layer 2 identifier is associated with a UE in a list of other UEs with which the UE can communicate using D2D communication, and the response message further includes the layer 2 identifier of the UE.

Example 55 may include the subject matter of any of Examples 49-54, further comprising: a unit for generating a relay frame based at least in part on a frame received from a transmitting UE, wherein the transmitting UE is in a list of other UEs with which the UE can communicate using D2D communication.

Example 56 may include an apparatus for wireless communication, comprising: a unit for performing group member discovery to discover at least one other UE with which the UE can communicate using device-to-device (D2D) communication; and a unit for discovering a potential relay UE for communicating with a remote UE, wherein the potential relay UE is one of the at least one other UE.

Example 57 may include the subject matter of Example 56, wherein the means for discovering the potential relay UE discovers the potential relay UE based at least in part on receiving an announce message from the potential relay UE.

Example 58 may include the subject matter of Example 57, wherein the announce message includes an identifier corresponding to the potential relay UE and a remote user information parameter.

Example 59 may include the subject matter of Example 56, further comprising sending a request message, wherein discovering the potential relay UE is based at least in part on receiving a response to the request message from the potential relay UE.

Example 60 may include a system comprising: one or more storage media having instructions; and processing circuitry coupled to the one or more storage media to execute the instructions, thereby: determining a list of other UEs with which a UE can communicate using device-to-device (D2D) communication; generating a message having a discovery type parameter set to UE-to-UE relay discovery and a parameter corresponding to another UE with which the UE can communicate using D2D communication; and generating a signal based at least in part on the message and controlling a transceiver circuit to send the signal.

Example 61 may include the subject matter of Example 60, wherein the message is an announce message.

Example 62 may include the subject matter of Example 60, wherein the message is a response message generated in response to a request message received from a sending UE, the sending UE being one of the other UEs with which the UE can communicate using D2D communication.

Example 63 may include the subject matter of Example 62, wherein the response message includes a remote user information parameter.

Example 64 may include the subject matter of Example 63, wherein the response message includes a remote UE layer 2 identifier associated with the remote user information parameter.

Example 65 may include the subject matter of Example 64, wherein the remote UE layer 2 identifier is associated with a UE in a list of other UEs with which the UE can communicate using D2D communication, and the response message further includes the layer 2 identifier of the UE.

Example 66 may include the subject matter of any of Examples 60-65, wherein the processing circuit is further used to: generate a relay frame based at least in part on a frame received from a transmitting UE, wherein the transmitting UE is in a list of other UEs with which the UE can communicate using D2D communication.

Example 67 may include one or more non-transitory computer-readable media comprising instructions for causing the electronic device to perform one or more elements of a method or process related to or described with respect to any of Examples 26-66 or any other method or process described herein when the instructions are executed by one or more processors of the electronic device.

The description of the illustrated embodiments herein, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Although specific implementations and examples are described herein for illustrative purposes, many alternative and/or equivalent embodiments or implementations that are believed to achieve the same purpose can be derived from the above specific embodiments without departing from the scope of the disclosure, as will be appreciated by those skilled in the art.

Claims (25)

1. An apparatus for wireless communication, comprising: One or more storage media containing instructions; and Processing circuitry, coupled to the one or more storage media to execute the instructions, thereby: Determine a list of user equipment (UEs) with which the device can communicate using device-to-device (D2D) communication; Based at least in part on the list, a declaration message is generated indicating that the device is capable of acting as a relay for D2D communication between the UEs in the list; and The signal is generated at least in part based on the announcement message, and the transceiver circuitry is controlled to transmit the signal. 2. The apparatus of claim 1, wherein the announcement message includes the list of the UE. 3. The apparatus of claim 2, wherein the announcement message includes a Layer 2 identifier and user information parameters associated with each UE in the list. 4. The apparatus of any one of claims 2-3, wherein the processing circuitry is further configured to: generate a relay frame based at least in part on frames received from a UE in the list. 5. The apparatus of claim 4, wherein the frame received from the UE includes a source layer 2 identifier ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "to relay". 6. The apparatus of claim 4, wherein the relay frame includes a source layer 2 identifier ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "self-relay". 7. A user equipment (UE), comprising: One or more storage media containing instructions; and Processing circuitry, coupled to the one or more storage media to execute the instructions, thereby: Determine a list of other UEs with which the UE can communicate using device-to-device (D2D) communication; Based at least in part on the list, a message is generated indicating that the UE can act as a relay for D2D communication between the other UEs in the list, the message having a discovery type parameter set as UE-to-UE relay discovery and parameters corresponding to another UE with which the UE can communicate using D2D communication; and The signal is generated at least in part based on the message, and the transceiver circuitry is controlled to transmit the signal. 8. The UE as claimed in claim 7, wherein the message is an announcement message. 9. The UE of claim 7, wherein the message is a response message generated in response to a request message received from a sending UE, the sending UE being one of the other UEs with which the UE can communicate using D2D communication. 10. The UE as claimed in claim 9, wherein the response message includes remote user information parameters. 11. The UE of claim 10, wherein the response message includes a remote UE layer 2 identifier associated with the remote user information parameter. 12. The UE of claim 11, wherein the remote UE layer 2 identifier is associated with a UE in the list of other UEs with which the UE can communicate using D2D communication, and the response message further includes the layer 2 identifier of the UE. 13. The UE of any one of claims 7-12, wherein the processing circuitry is further configured to: generate a relay frame based at least in part on a frame received from the transmitting UE, wherein the transmitting UE is in the list of other UEs with which the UE can communicate using D2D communication. 14. A method for wireless communication, comprising: Determine a list of user equipment (UEs) with which the device can communicate using device-to-device (D2D) communication; Based at least in part on the list, a declaration message is generated indicating that the device is capable of acting as a relay for D2D communication between the UEs in the list; The signal is generated at least in part based on the announcement message; and The transceiver circuit is controlled to send the signal. 15. The method of claim 14, wherein the announcement message includes the list of the UEs. 16. The method of claim 15, wherein the announcement message includes a Layer 2 identifier and user information parameters associated with each UE in the list. 17. The method of any one of claims 15-16, further comprising: generating a relay frame based at least in part on frames received from a UE in the list. 18. The method of claim 17, wherein the frame received from the UE includes a source layer 2 identifier ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "to relay". 19. The method of claim 17, wherein the relay frame includes a source layer 2 identifier ID field, a destination layer 2 ID field, a relay layer 2 ID field, and a direction field set to "self-relay". 20. A method for wireless communication, comprising: The executive group members discovered at least one other UE with which the user equipment (UE) could communicate using device-to-device (D2D) communication; and Discover a potential relay UE for D2D communication between the UE and a remote UE, wherein the potential relay UE is one of the at least one other UE. 21. The method of claim 20, wherein the discovery of the potential relay UE is based at least in part on receiving an announcement message from the potential relay UE. 22. The method of claim 21, wherein the announcement message includes an identifier and remote user information parameters corresponding to the potential relay UE. 23. An apparatus for wireless communication, comprising: A unit for determining a list of user equipment (UE) with which the device can communicate using device-to-device (D2D) communication; A unit for generating, at least in part, a declaration message based on the list, indicating that the device is capable of acting as a relay for D2D communication between the UEs in the list; A unit for generating a signal based at least in part on the announcement message; and A unit used to control the transceiver circuit to send the signal. 24. The apparatus of claim 23, wherein the announcement message includes the list of the UE. 25. The apparatus of claim 24, wherein the announcement message includes a Layer 2 identifier and user information parameters associated with each UE in the list.