Patent Publication Number: US-2022217622-A1

Title: Selection of proximity services relay

Description:
CROSS REFERENCES 
     The present Application for Patent is a continuation of U.S. patent application Ser. No. 15/061,092 by Zisimopoulos, et al., entitled “Selection of Proximity Services Relay,” filed Mar. 4, 2016, which claims priority to U.S. Provisional Patent Application No. 62/139,335 by Zisimopoulos, et al., entitled “Selection of Proximity Services Relay,” filed Mar. 27, 2015; each of which is assigned to the assignee hereof and expressly incorporated by reference herein. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure, for example, relates to wireless communication systems, and more particularly to techniques for selecting a proximity services (ProSe) relay at a user equipment (UE). 
     Description of Related Art 
     Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems. 
     By way of example, a wireless multiple-access communication system may include a number of base stations, Wi-Fi access points, or other nodes, each simultaneously supporting communication for multiple communication devices, otherwise known as UEs. A base station or Wi-Fi access point may communicate with UEs on downlink channels (e.g., for transmissions from a base station or Wi-Fi access point to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or Wi-Fi access point). 
     Each base station within a wireless communication system may be associated with a coverage area. When a UE is operated inside the coverage area of a base station, the UE may connect to a network to which the base station provides access by communicating with the base station. When the UE is operated outside the coverage area of the base station, the UE may in some cases be able to communicate with the base station, and connect to the network, via a ProSe relay. 
     SUMMARY 
     The present disclosure, for example, relates to one or more techniques for selecting a proximity services (ProSe) relay at a UE. Although “3rd Generation Partnership Project” (3GPP) standards such as TS 23.303 and TR 23.713 describe procedures for a user equipment (UE) to connect to a ProSe relay, 3GPP standards do not indicate how to select a more (or most) appropriate ProSe relay when multiple ProSe relay candidates are available. The 3GPP standards therefore allow a UE to connect to a ProSe relay despite a better ProSe relay candidate being available. Techniques described in the present disclosure enable a UE to select an appropriate (or most appropriate) ProSe relay from among a plurality of ProSe relay candidates. 
     In a first set of illustrative examples, a method for wireless communication at a UE is described. In one configuration, the method includes configuring the UE with a relay selection rule; receiving at least one ProSe discovery message from each of a plurality of ProSe relay candidates providing access to a network; evaluating the received ProSe discovery messages with respect to the relay selection rule; selecting a first ProSe relay candidate from the plurality of ProSe relay candidates based at least in part on the evaluating; and connecting to the network via the first ProSe relay candidate. 
     In some examples of the method, evaluating the received ProSe discovery messages with respect to the relay selection rule may include identifying a ProSe discovery message received from the first ProSe relay candidate as complying with the relay selection rule to a greater extent than at least one other ProSe discovery message received from at least one other ProSe relay candidate of the plurality of ProSe relay candidates. In some examples of the method, the at least one ProSe discovery message may include a relay offer message, and evaluating the received ProSe discovery messages with respect to the relay selection rule may include evaluating the relay offer message with respect to the relay selection rule. In some examples, the at least one ProSe discovery message may further include a Multimedia Broadcast Multicast Service (MBMS) relay information message, and the method may further include determining the MBMS relay information message identifies at least one MBMS desired by the UE; and further selecting the first ProSe relay candidate based at least in part on the MBMS relay information message identifying the at least one MBMS desired by the UE. In some examples of the method, the MBMS relay information message may include at least a E-UTRAN cell identity (ECI), or at least one temporary mobile group identity (TMGI), or at least one ProSe Group Identifier (ID), or a combination thereof 
     In some examples of the method, the relay selection rule may include at least one relay radio layer condition. The at least one relay radio layer condition may include at least a threshold relay-to-network reference signal received power (RSRP), or a threshold relay-to-network reference signal received quality (RSRQ), or a threshold relay-to-UE RSRP, or a provisioned ProSe Relay Indication (PRI) indicating a relay selection policy for accessing the network, or a radio validity condition, or a combination thereof. In some examples, the radio validity condition may include at least a first radio validity condition indicating that each threshold condition of the at least one relay radio layer condition needs to be satisfied, or a second radio validity condition indicating that at least one threshold condition of the at least one relay radio layer condition needs to be satisfied. In some examples, the method may further include performing a bitwise logical AND between the provisioned PRI and a PRI received in the ProSe discovery messages. In some examples, the method may further include measuring a relay-to-UE RSRP; comparing the measured relay-to-UE RSRP to the threshold relay-to-UE RSRP; and performing a bitwise logical AND between the provisioned PRI and a PRI received in the ProSe discovery messages. In some examples of the method, the relay selection rule may further include at least one upper layer condition. The at least one upper layer condition may include at least a public land mobile network identifier (PLMN ID), or a ProSe Relay UE ID, or relay connectivity information, or relay status information, or an indicator of service continuity support, or a combination thereof. In some examples, the method may further include evaluating the at least one upper layer condition with respect to the relay selection rule upon determining a compliance of the at least one relay radio layer condition with the relay selection rule. In some examples, the method may further include evaluating the at least one relay radio layer condition with respect to the relay selection rule upon determining a compliance of the at least one upper layer condition with the relay selection rule. In some examples of the method, the UE may be configured according to the relay selection rule by a ProSe function. 
     In a second set of illustrative examples, an apparatus for wireless communication at a UE is described. In one configuration, the apparatus may include means for configuring the UE with a relay selection rule; means for receiving at least one ProSe discovery message from each of a plurality of ProSe relay candidates providing access to a network; means for evaluating the received ProSe discovery messages with respect to the relay selection rule; means for selecting a first ProSe relay candidate from the plurality of ProSe relay candidates based at least in part on the evaluating; and means for connecting to the network via the first ProSe relay candidate. In some examples, the apparatus may further include means for implementing one or more aspects of the method for wireless communication described above with respect to the first set of illustrative examples. 
     In a third set of illustrative examples, another apparatus for wireless communication at a UE is described. In one configuration, the apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to receive a relay selection rule; to receive at least one ProSe discovery message from each of a plurality of ProSe relay candidates providing access to a network; to evaluate the received ProSe discovery messages with respect to the relay selection rule; to select a first ProSe relay candidate from the plurality of ProSe relay candidates based at least in part on the evaluating; and to connect to the network via the first ProSe relay candidate. In some examples, the instructions may also be executable by the processor to implement one or more aspects of the method for wireless communication described above with respect to the first set of illustrative examples. 
     In a fourth set of illustrative examples, a non-transitory computer-readable medium storing computer-executable code for wireless communication is described. In one configuration, the code may be executable by a processor to receive a relay selection rule; to receive at least one ProSe discovery message from each of a plurality of ProSe relay candidates providing access to a network; to evaluate the received ProSe discovery messages with respect to the relay selection rule; to select a first ProSe relay candidate from the plurality of ProSe relay candidates based at least in part on the evaluating; and to connect to the network via the first ProSe relay candidate. In some examples, the code may also be executable by the processor to implement one or more aspects of the method for wireless communication described above with respect to the first set of illustrative examples. 
     In a fifth set of illustrative examples, a method for wireless communication at a ProSe relay candidate is described. In one configuration, the method includes receiving, from a network, a ProSe Relay Indication (PRI); broadcasting at least one ProSe discovery message that includes the PRI; and receiving a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. 
     In some examples, the method may further include communicating with the network over a first communication link; measuring at least a relay-to-network RSRP, or a relay-to-network RSRQ, or a combination thereof; and indicating at least the measured relay-to-network RSRP, or the measured relay-to-network RSRQ, or a combination thereof in the at least one ProSe discovery message. In some examples of the method, the at least one ProSe discovery message may include a relay offer message. In some examples, the at least one ProSe discovery message may further include a MBMS relay information message. 
     In some examples of the method, the at least one ProSe discovery message may include at least one relay radio layer condition and at least one upper layer condition. In some examples of the method, the PRI may be received in a system information block (SIB) or a unicast radio resource control (RRC) message. 
     In a sixth set of illustrative examples, an apparatus for wireless communication at a ProSe relay candidate is described. In one configuration, the apparatus may include means for receiving, from a network, a PRI; means for broadcasting at least one ProSe discovery message that includes the PRI; and means for receiving a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. In some examples, the apparatus may further include means for implementing one or more aspects of the method for wireless communication described above with respect to the fifth set of illustrative examples. In some examples, the instructions may also be executable by the processor to implement one or more aspects of the method for wireless communication described above with respect to the fifth set of illustrative examples. 
     In a seventh set of illustrative examples, another apparatus for wireless communication at a ProSe relay candidate is described. In one configuration, the apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to receive, from a network, a PRI; to broadcast at least one ProSe discovery message that includes the PRI; and to receive a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. 
     In an eighth set of illustrative examples, another non-transitory computer-readable medium storing computer-executable code for wireless communication is described. In one configuration, the code may be executable by a processor to receive, from a network, a PRI; to broadcast at least one ProSe discovery message that includes the PRI; and to receive a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. In some examples, the code may also be executable by the processor to implement one or more aspects of the method for wireless communication described above with respect to the fifth set of illustrative examples. 
     The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limits of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A further understanding of the nature and advantages of the present invention may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. 
         FIG. 1  illustrates an example of a wireless communication system, in accordance with various aspects of the disclosure; 
         FIG. 2  is a swim lane diagram illustrating selection of a proximity services (ProSe) relay candidate, in accordance with various aspects of the present disclosure; 
         FIG. 3  shows an exemplary structure of a relay offer message, in accordance with various aspects of the present disclosure; 
         FIG. 4  shows an exemplary structure of a Multimedia Broadcast Multicast Service (MBMS) relay information message, in accordance with various aspects of the present disclosure; 
         FIG. 5  shows a block diagram of a device for use in wireless communication, in accordance with various aspects of the present disclosure; 
         FIG. 6  shows a block diagram of a device for use in wireless communication, in accordance with various aspects of the present disclosure; 
         FIG. 7  shows a block diagram of a device for use in wireless communication, in accordance with various aspects of the present disclosure; 
         FIG. 8  shows a block diagram of a device for use in wireless communication, in accordance with various aspects of the present disclosure; 
         FIG. 9  shows a block diagram of a user equipment (UE) for use in wireless communication, in accordance with various aspects of the present disclosure; 
         FIG. 10  shows a block diagram of a ProSe relay candidate for use in wireless communication, in accordance with various aspects of the present disclosure; 
         FIG. 11  is a flow chart illustrating an exemplary method for wireless communication at a UE, in accordance with various aspects of the present disclosure; 
         FIG. 12  is a flow chart illustrating an exemplary method for wireless communication at a UE, in accordance with various aspects of the present disclosure; 
         FIG. 13  is a flow chart illustrating an exemplary method for wireless communication at a ProSe relay candidate, in accordance with various aspects of the present disclosure; and 
         FIG. 14  is a flow chart illustrating an exemplary method for wireless communication at a ProSe relay candidate, in accordance with various aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Techniques are described for selecting a proximity services (ProSe) relay at a user equipment (UE). A ProSe relay is a device capable of relaying communications between a network (e.g., a base station that provides access to the network) and one or more UEs. A ProSe relay may in some cases be a UE capable of providing proximity services. ProSe relays may be used, for example, to relay public safety broadcasts to UEs, or to more generally provide range extension for a wireless communication system (e.g., for a Long Term Evolution (LTE) or LTE Advanced (LTE-A) network). 
     The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in other examples. 
       FIG. 1  illustrates an example of a wireless communication system  100 , in accordance with various aspects of the disclosure. The wireless communication system  100  may include base stations  105 , UEs  115 , and a core network  130 . The core network  130  may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations  105  may interface with the core network  130  through backhaul links  132  (e.g., S1, etc.) and may perform radio configuration and scheduling for communication with the UEs  115 , or may operate under the control of a base station controller (not shown). In various examples, the base stations  105  may communicate, either directly or indirectly (e.g., through core network  130 ), with each other over backhaul links  134  (e.g., X1, etc.), which may be wired or wireless communication links. 
     The base stations  105  may wirelessly communicate with the UEs  115  via at least one base station antenna. Each of the base station  105  sites may provide communication coverage for a respective geographic coverage area  110 . In some examples, a base station  105  may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area  110  for a base station  105  may be divided into sectors making up a portion of the coverage area (not shown). The wireless communication system  100  may include base stations  105  of different types (e.g., macro or small cell base stations). There may be overlapping geographic coverage areas  110  for different technologies. 
     In some examples, the wireless communication system  100  may include an LTE/LTE-A network. In LTE/LTE-A networks, the term evolved Node B (eNB) may be used to describe the base stations  105  (or entities including one or more base stations  105 ). The wireless communication system  100  may be a Heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station  105  may provide communication coverage for a macro cell, a small cell, or other types of cell. The term “cell” is a  3 rd Generation Partnership Project (3GPP) term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context. 
     A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell may be a lower-powered base station, as compared with a macro cell that may operate in the same or different (e.g., dedicated, shared, etc.) radio frequency spectrums as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell may cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell also may cover a relatively small geographic area (e.g., a home) and may provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers). 
     The wireless communication system  100  may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations. 
     The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use Hybrid ARQ (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE  115  and the base stations  105  or core network  130  supporting radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels. 
     The UEs  115  may be dispersed throughout the wireless communication system  100 , and each UE  115  may be stationary or mobile. A UE  115  may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE  115  may be a wireless communication device, a personal computer (e.g., a laptop computer, a netbook computer, a tablet computer, etc.), a handheld device, a cellular telephone, a smart phone, a cordless phone, a wireless modem, a wireless local loop (WLL) station, a personal digital assistant (PDA), a digital video recorder (DVR), an internet appliance, a gaming console, an e-reader, etc. A UE may be able to communicate with various types of base stations and network equipment, including macro eNBs, small cell eNBs, relay base stations, and the like. A UE may also be able to communicate using different radio access technologies (RATs), such as a cellular RAT (e.g., an LTE/LTE-A RAT), a Wi-Fi RAT, or other RATs. 
     The communication links  125  shown in wireless communication system  100  may include downlink (DL) transmissions, from a base station  105  to a UE  115 , or uplink (UL) transmissions, from a UE  115  to a base station  105 . The downlink transmissions may also be called forward link transmissions, while the uplink transmissions may also be called reverse link transmissions. 
     In some examples, each communication link  125  may include at least one carrier, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. The communication links  125  may transmit bidirectional communications using a frequency domain duplexing (FDD) operation (e.g., using paired spectrum resources) or a time domain duplexing (TDD) operation (e.g., using unpaired spectrum resources). Frame structures for FDD operation (e.g., frame structure type 1) and TDD operation (e.g., frame structure type 2) may be defined. 
     In some examples of the wireless communication system  100 , base stations  105  or UEs  115  may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations  105  and UEs  115 . Additionally or alternatively, base stations  105  or UEs  115  may employ multiple-input, multiple-output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data. 
     The wireless communication system  100  may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or dual-connectivity operation. A carrier may also be referred to as a component carrier (CC), a layer, a channel, etc. The terms “carrier,” “component carrier,” “cell,” and “channel” may be used interchangeably herein. A UE  115  may have multiple downlink CCs and at least one uplink CC for carrier aggregation. Carrier aggregation may be used with both FDD and TDD component carriers. 
     As shown in  FIG. 1 , the wireless communication system  100  may also include ProSe relays or ProSe relay candidates  135 . The ProSe relay candidates may relay communications between a base station  105  and UE  115  when the UE  115  is operated outside the coverage area of any base station  105 . Thus, for example, the ProSe relay candidate  135 - a  may relay communications between the out-of-coverage UE  115 - a  and the base station  105 - a.  In some examples, the ProSe relay candidates  135  may themselves be UEs. Communications between UEs  115  and ProSe relay candidates  135  may be made using a Device-to-Device (D2D) communication protocol, such as a PC 5  communication protocol. LTE/LTE-A communications between ProSe relay candidates  135  and base stations  105  may be made over Universal Mobile Telecommunication System (UMTS) air interfaces, also known as Uu interfaces. 
       FIG. 2  is a swim lane diagram  200  illustrating selection of a ProSe relay candidate, in accordance with various aspects of the present disclosure. By way of example, the communications shown in  FIG. 2  occur between a ProSe function  205 , a base station  105 - b,  a ProSe relay candidate  135 - b,  and a UE  115 - b.  The base station  105 - b,  ProSe relay candidate  135 - b,  and UE  115 - b  may be respective examples of aspects of the base stations  105 , ProSe relay candidates  135 , and UEs  115  described with reference to  FIG. 1 . 
     At  210 , the ProSe function may configure the UE  115 - b  with a relay selection rule (e.g., configure the UE to evaluate the relay selection rule). In some examples, the ProSe function may be provided by a server (e.g., a server of the core network  130  described with reference to  FIG. 1 ). 
     In some embodiments, the relay selection rule may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a threshold relay-to-network reference signal received power (RSRP) (e.g., a threshold UuRSRP), a threshold relay-to-network reference signal received quality (RSRQ) (e.g., a threshold UuRSRQ), a threshold relay-to-UE RSRP (e.g., a threshold PCSRSRP), a provisioned ProSe Relay Indication (PRI) indicating a relay selection policy for accessing a network, a radio validity condition, or a combination thereof. The radio validity condition may include a first radio validity condition indicating that each threshold condition of the at least one relay radio layer condition needs to be satisfied, or a second radio validity condition indicating that at least one threshold condition of the at least one relay radio layer condition needs to be satisfied. The upper layer condition(s) may include, for example, a public land mobile network identifier (PLMN ID) indicating a relay Home PLMN (HPLMN) that the UE  115 - b  is allowed to connect to, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. 
     At  215 , the base station  105 - b  may transmit a PRI to the ProSe relay candidate  135 - b.  The PRI may include a bitmap (i.e., a one-dimensional bit array) that may be used by UEs to determine whether they should select the ProSe relay candidate  135 - b  for communicating with a network to which the base station  105 - b  provides access. The meaning of each bit in the PRI may be operator specific. In some examples, the PRI may be received in a system information block (SIB) or a unicast RRC message. 
     At  220 , the ProSe relay candidate  135 - b  may broadcast at least one ProSe discovery message  220  (e.g., in accordance with PC5-D discovery techniques). The at least one ProSe discovery message  220  may include a relay offer message  225  and/or a Multimedia Broadcast Multicast Service (MBMS) relay information message  230 . The relay offer message  225  may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a relay-to-network RSRP, a relay-to-network RSRQ, a PRI of the ProSe relay candidate  135 - b,  or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message  230  may identify MBMSs offered by the ProSe relay candidate  135 - b.  Although not shown in  FIG. 2 , the UE  115 - b  may also receive ProSe discovery messages from other ProSe relay candidates. 
     At block  235 , the UE  115 - b  may evaluate the received ProSe discovery messages with respect to the relay selection rule received at  210 . In some embodiments, the UE  115 - b  may evaluate the received ProSe discovery messages to identify one or more ProSe discovery messages that comply with the relay selection rule (e.g., the UE  115 - b  may identify a first ProSe discovery message of a first ProSe relay candidate (e.g., the ProSe relay candidate  135 - b ), which first ProSe discovery message complies with the relay selection rule). In other embodiments, the UE  115 - b  may evaluate more than one (or all) of the received ProSe discovery messages and identify a ProSe discovery message received from one of the ProSe relay candidates (e.g., the ProSe relay candidate  135 - b ) as complying with the relay selection rule to a greater extent than at least one other ProSe discovery message received from at least one other ProSe relay candidate. The UE  115 - b  may also identify a ProSe discovery message that complies with the relay selection rule better than any other discover message. 
     At block  240 , the UE  115 - b  may select a ProSe relay candidate (e.g., the ProSe relay candidate  135 - b ) for communicating with the network, based at least in part on the evaluations performed at block  235 . At  245 , the UE may transmit a relay connection request to the ProSe relay candidate  135 - b.  Upon acceptance of the relay connection request by the ProSe relay candidate  135 - b,  the UE  115 - b  may engage in communications with the network via relay communications  250  with the ProSe relay candidate  135 - b  and backhaul communications  255  between the ProSe relay candidate  135 - b  and the base station  105 - b.    
       FIG. 3  shows an exemplary structure of a relay offer message  300 , in accordance with various aspects of the present disclosure. The relay offer message  300  may be an example of a relay offer message transmitted by one of the ProSe relay candidates  135  described with reference to  FIG. 1 or 2 . 
     The relay offer message  300  may include a number of ProSe discovery message identifiers (IDs)  305 , a number of upper layer conditions  310 , or a number of relay radio layer conditions  315 . The ProSe discovery message IDs  305  may include types of identifiers that are common to all ProSe discovery messages, and may include, for example, a message type  320  and a discovery type  325 . In accordance with 3GPP Specification TS 24.334, and by way of example, the message type  320  may be an announcement (Model A) or a solicitation/response (Model B). Also in accordance with 3GPP, and by way of further example, the discovery type  325  may indicate whether a ProSe discovery message is a UE-to-network relay discovery message or a group member discovery message. 
     The upper layer conditions  310  may be specific to relay offer messages and may include, for example, a ProSe Relay UE ID  330 , a PLMN ID  335 , relay connectivity information  340 , relay status information  345 , or an indicator of service continuity support  350 . The ProSe Relay UE ID  330  may be a link layer identifier used for direct communication, and may be associated with a packet data network (PDN) connection the ProSe relay candidate has established. The PLMN ID  335  may identify the PLMN to which radio frequencies used on a communication link established with a UE belong. If the radio frequencies are shared between multiple PLMNs, or not allocated to any PLMN, the PLMN ID  335  may be configured by the ProSe relay candidate&#39;s HPLMN. The relay connectivity information  340  may include a parameter identifying connectivity that the ProSe relay candidate provides (e.g., assigned access point name (APN) information). Because APN information can be long (e.g., 2000 bits), the relay connectivity information  340  may include an encoded index to APN information, to reduce its size. The relay status information  345  may include status or maintenance flags indicating, for example, whether the ProSe relay candidate is temporarily without connectivity or has low battery power. The relay status information  345  may enable a UE considering the ProSe relay candidate to pass on the ProSe relay candidate or seek/reselect another ProSe relay candidate. The indicator of service continuity support  350  may indicate whether the ProSe relay candidate is capable of providing service continuity. 
     The relay radio layer conditions  315  may include, for example, a backhaul type  355 , a relay-to-network RSRP  360  (e.g., a UuRSRP), a relay-to-network RSRQ  365  (e.g., a UuRSRQ), a system bandwidth indicator  370 , or a PRI  375 . The backhaul type  355  may indicate a radio access technology (RAT) used for relay backhaul. The relay-to-network RSRP  360  may include a UuRSRP measured by the ProSe relay candidate (e.g., an LTE/LTE-A Uu Qrxlevmeas in RRC_IDLE, or a PCell RSRP in RRC_CONNECTED, as defined in 3GPP Specifications TS 36.304 and TS 36.331). The relay-to-network RSRQ  365  may include a UuRSRQ measured by the ProSe relay candidate (e.g., an LTE/LTE-A Uu Qqualmeas in RRC_IDLE, or a PCell RSRQ in RRC_CONNECTED, as defined in 3GPP Specifications TS 36.304 and TS 36.331). The system bandwidth indicator  370  may indicate a bandwidth between the ProSe relay candidate and the network. The PRI  375  may be provided to the ProSe relay candidate by the network and indicate a relay selection policy for accessing the network. The PRI  375  may include a bitmap (i.e., a one-dimensional bit array) that may be used by UEs to determine whether they should select the ProSe relay candidate for communicating with the network. The meaning of each bit in the PRI  375  may be operator specific. 
       FIG. 4  shows an exemplary structure of an MBMS relay information message  400 , in accordance with various aspects of the present disclosure. The MBMS relay information message  400  may be an example of an MBMS relay information message transmitted by one of the ProSe relay candidates  135  described with reference to  FIG. 1 or 2 . 
     The MBMS relay information message  400  may include a number of ProSe discovery message identifiers (IDs)  405  or MBMS relay information  410 . The ProSe discovery message IDs  405  may include types of identifiers that are common to all ProSe discovery messages, and may include, for example, a message type  415  and a discovery type  420 . In accordance with 3GPP Specification TS 24.334, and by way of example, the message type  415  may be an announcement (Model A) or a solicitation/response (Model B). Also in accordance with 3GPP, and by way of further example, the discovery type  420  may indicate whether a ProSe discovery message is a UE-to-network relay discovery message or a group member discovery message. 
     The MBMS relay information  410  may be specific to MBMS relay information messages and may include, for example, an E-UTRAN cell identity (ECI)  425 , at least one temporary mobile group identity (TMGI)  430 , or at least one ProSe Group ID  435 . The ECI  425  may identify the Cell ID of the cell on which the ProSe relay candidate is camped or connected. The ECI  425  may be used by a UE to report location information (e.g., in order to enable counting of UEs participating in Group Communication System Enablers (GCSE) or Mission Critical Push to Talk (MCPTT) services, to trigger an eMBMS session start). The at least one TMGI  430  may indicate the TMGI(s) of MBMS(s) that the ProSe relay candidate is currently serving. The at least one ProSe Group ID  435  may indicate Group ID(s) corresponding to respective ones of the TMGI(s)  430 . 
       FIG. 5  shows a block diagram  500  of a device  115 - c  for use in wireless communication, in accordance with various aspects of the present disclosure. The device  115 - c  may be an example of aspects of one or more of the UEs  115  described with reference to  FIG. 1 or 2 . The device  115 - c  may also be or include a processor. The device  115 - c  may include a receiver module  510 , a wireless communication management module  520 , or a transmitter module  530 . Each of these components may be in communication with each other. 
     The components of the device  115 - c  may, individually or collectively, be implemented using one or more application-specific integrated circuits (ASICs) adapted to perform some or all of the applicable functions in hardware. Alternatively, the functions may be performed by one or more other processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., Structured/Platform ASICs, Field Programmable Gate Arrays (FPGAs), a System-on-Chip (SoC), and/or other types of Semi-Custom ICs), which may be programmed in any manner known in the art. The functions of each module may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by one or more general or application-specific processors. 
     In some examples, the receiver module  510  may include at least one radio frequency (RF) receiver. The receiver module  510  or RF receiver may be used to receive various types of data or control signals (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system  100  described with reference to  FIG. 1 . In some examples, the transmissions may include D2D communications and/or LTE/LTE-A communications. 
     In some examples, the transmitter module  530  may include at least one RF transmitter. The transmitter module  530  or RF transmitter may be used to transmit various types of data or control signals (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system  100  described with reference to  FIG. 1 . In some examples, the transmissions may include D2D communications and/or LTE/LTE-A communications. 
     The wireless communication management module  520  may be used to manage one or more aspects of wireless communication for the device  115 - c.  In some examples, the wireless communication management module  520  may include a relay selection rule management module  535 , a ProSe discovery message processing module  540 , a ProSe relay candidate selection module  545 , or a network connection management module  550 . 
     The relay selection rule management module  535  may be used to receive a relay selection rule. In some examples, the relay selection rule may be received from a ProSe function that configures the device  115 - c  in accordance with the relay selection rule (e.g., configures the ProSe discovery message processing module  540  to evaluate the relay selection rule). In some examples, the ProSe function may be provided by a server (e.g., a server of the core network  130  described with reference to  FIG. 1 ). 
     The ProSe discovery message processing module  540  may be used to receive at least one ProSe discovery message from each of a plurality of ProSe relay candidates. Each of the ProSe relay candidates may provide access to a network. The ProSe discovery message processing module  540  may also be used to evaluate the received ProSe discovery messages with respect to the relay selection rule. In some embodiments, the ProSe discovery message processing module  540  may evaluate the received ProSe discovery messages to identify one or more ProSe discovery messages that comply with the relay selection rule (e.g., the ProSe discovery message processing module  540  may identify a first ProSe discovery message of a first ProSe relay candidate, which first ProSe discovery message complies with the relay selection rule). In other embodiments, the ProSe discovery message processing module  540  may evaluate more than one (or all) of the received ProSe discovery messages and identify a ProSe discovery message received from one of the ProSe relay candidates (e.g., the first ProSe relay candidate) as complying with the relay selection rule to a greater extent than at least one other ProSe discovery message received from at least one other ProSe relay candidate. The ProSe discovery message processing module  540  may also identify a ProSe discovery message that complies with the relay selection rule better than any other discover message. 
     The ProSe relay candidate selection module  545  may be used to select a first ProSe relay candidate from the plurality of ProSe relay candidates based at least in part on the evaluating done by the ProSe discovery message processing module  540 . 
     The network connection management module  550  may be used to connect a UE include the device  115 - c  to the network via the first ProSe relay candidate. 
       FIG. 6  shows a block diagram  600  of a device  115 - d  for use in wireless communication, in accordance with various aspects of the present disclosure. The device  115 - d  may be an example of aspects of one or more of the UEs or devices  115  described with reference to  FIG. 1, 2 , or  5 . The device  115 - d  may also be or include a processor. The device  115 - d  may include a receiver module  510 - a,  a wireless communication management module  520 - a,  or a transmitter module  530 - a,  which may be respective examples of the receiver module  510 , the wireless communication management module  520 , and the transmitter module  530  described with reference to  FIG. 5 . Each of these components may be in communication with each other. 
     The components of the device  115 - d  may, individually or collectively, be implemented using one or more ASICs adapted to perform some or all of the applicable functions in hardware. Alternatively, the functions may be performed by one or more other processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., Structured/Platform ASICs, FPGAs, a SoC, and/or other types of Semi-Custom ICs), which may be programmed in any manner known in the art. The functions of each module may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by one or more general or application-specific processors. 
     The wireless communication management module  520 - a  may be used to manage one or more aspects of wireless communication for the device  115 - d.  In some examples, the wireless communication management module  520 - a  may include a relay selection rule management module  535 - a,  a ProSe discovery message processing module  540 - a,  a measurement management module  635 , a ProSe relay candidate selection module  545 - a,  or a network connection management module  550 - a.    
     The relay selection rule management module  535 - a  may be used to receive a relay selection rule. In some examples, the relay selection rule may be received from a ProSe function that configures the device  115 - d  in accordance with the relay selection rule (e.g., configures the ProSe discovery message processing module  540 - a  to evaluate the relay selection rule). In some examples, the ProSe function may be provided by a server (e.g., a server of the core network  130  described with reference to  FIG. 1 ). 
     In some embodiments, the relay selection rule may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a threshold relay-to-network RSRP, a threshold relay-to-network RSRQ, a threshold relay-to-UE RSRP, a provisioned PRI indicating a relay selection policy for accessing a network, a radio validity condition, or a combination thereof. The radio validity condition may include a first radio validity condition indicating that each threshold condition of the at least one relay radio layer condition needs to be satisfied, or a second radio validity condition indicating that at least one threshold condition of the at least one relay radio layer condition needs to be satisfied. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof 
     The measurement management module  635  may be used to measure a relay-to-UE RSRP (e.g., a ProSe relay candidate-to-UE RSRP). 
     The ProSe discovery message processing module  540 - a  may be used to receive at least one ProSe discovery message from each of a plurality of ProSe relay candidates. Each of the ProSe relay candidates may provide access to a network. In some embodiments, the at least one ProSe discovery message may include a relay offer message and/or a MBMS relay information message. The relay offer message may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a relay-to-network RSRP, a relay-to-network RSRQ, a PRI of the ProSe relay candidate, or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message may identify MBMSs offered by the ProSe relay candidate. 
     The ProSe discovery message processing module  540 - a  may include a relay offer message evaluation module  640  or an MBMS relay information message evaluation module  660 . The relay offer message evaluation module  640  may be used to evaluate the relay offer message with respect to the relay selection rule and include a PRI evaluation module  645 , a threshold condition evaluation module  650 , and an upper layer condition evaluation module  655 . The relay offer message evaluation module  640  may be configured to evaluate the at least one relay radio layer condition with respect to the relay selection rule first, and to evaluate the at least one upper layer condition with respect to the relay selection rule upon determining a compliance of the at least one relay radio layer condition with the relay selection rule. Alternatively, the relay offer message evaluation module  640  may be configured to evaluate the at least one upper layer condition with respect to the relay selection rule first, and to evaluate the at least one relay radio layer condition with respect to the relay selection rule upon determining a compliance of the at least one upper layer condition with the relay selection rule. 
     The PRI evaluation module  645  may be used to perform a bitwise logical AND between the provisioned PRI of the relay selection rule and a PRI received in a relay offer message (e.g., in a ProSe discovery message). When the bitwise logical AND evaluates to TRUE, the ProSe discovery message processing module  540 - a  may consider the PRI to comply with the relay selection rule, and the evaluation of ProSe discovery messages corresponding to a ProSe relay candidate may pass to the threshold condition evaluation module  650 . When the bitwise logical AND evaluates to FALSE, the ProSe discovery message processing module  540 - a  may consider the PRI to not comply with the relay selection rule, and if one or more other ProSe relay candidates are available, ProSe discovery messages corresponding to one or more additional ProSe relay candidates may be evaluated. 
     The threshold condition evaluation module  650  may be used to respectively compare a relay-to-network RSRP and relay-to-network RSRQ received in a relay offer message, if present, to a threshold relay-to-network RSRP and threshold relay-to-network RSRQ, if present, specified by the relay selection rule. When a value satisfies its threshold, the ProSe discovery message processing module  540 - a  may consider the value to comply with the relay selection rule. When a value does not satisfy its threshold, the ProSe discovery message processing module  540 - a  may consider the value to not comply with the relay selection rule. The threshold condition evaluation module  650  may also compare the measured relay-to-UE RSRP to a threshold relay-to-UE RSRP, if present, specified by the relay selection rule. When the measured value satisfies the threshold, the ProSe discovery message processing module  540 - a  may consider the measured value to comply with the relay selection rule. When the measured value does not satisfy the threshold, the ProSe discovery message processing module  540 - a  may consider the measured value to not comply with the relay selection rule. Still further, the threshold condition evaluation module  650  may be used to determine whether a radio validity condition of the relay selection rule, if present, is satisfied. When it is determined that the radio validity condition is satisfied, the evaluation of ProSe discovery messages corresponding to a ProSe relay candidate may pass to the upper layer condition evaluation module  655 . When it is determined that the radio validity condition is not satisfied, and if one or more other ProSe relay candidates are available, ProSe discovery messages corresponding to one or more additional ProSe relay candidates may be evaluated. 
     The upper layer condition evaluation module  655  may be used to compare the upper layer conditions indicated in a relay offer message to respective upper layer conditions specified by the relay selection rule, to enable the ProSe discovery message processing module  540 - a  to determine whether the upper layer conditions indicated in the relay offer message comply with the relay selection rule. When it is determined that the upper layer conditions indicated in the relay offer message comply with the relay selection rule, the evaluation of ProSe discovery messages corresponding to a ProSe relay candidate may pass to the MBMS relay information message evaluation module  660 . When it is determined that the upper layer conditions indicated in the relay offer message do not comply with the relay selection rule, and if one or more other ProSe relay candidates are available, ProSe discovery messages corresponding to one or more additional ProSe relay candidates may be evaluated. 
     The MBMS relay information message evaluation module  660  may be used to determine whether an MBMS relay information message corresponding to a ProSe relay candidate, if any, identifies at least one MBMS desired by a UE. When it is determined that the MBMS relay information message identifies at least one MBMS desired by the UE, the ProSe discovery message processing module  540 - a  may pass an identity of the ProSe relay candidate to the ProSe relay candidate selection module  545 - a.  When it is determined that the MBMS relay information message does not identify at least one MBMS desired by the UE, and if one or more other ProSe relay candidates are available, ProSe discovery messages corresponding to one or more additional ProSe relay candidates may be evaluated. 
     The ProSe relay candidate selection module  545 - a  may be used to select a ProSe relay candidate based at least in part on the evaluations and identifications performed by the ProSe discovery message processing module  540 - a.    
     The network connection management module  550 - a  may be used to connect a UE include the device  115 - d  to the network via the ProSe relay candidate. 
     In some examples, aspects of the devices  515  described with reference to  FIGS. 5 and 6  may be combined. 
       FIG. 7  shows a block diagram  700  of a device  135 - c  for use in wireless communication, in accordance with various aspects of the present disclosure. The device  135 - c  may be an example of aspects of one or more of the ProSe relay candidates  135  described with reference to  FIG. 1 or 2 . The device  135 - c  may also be or include a processor. The device  135 - c  may include a receiver module  710 , a wireless communication management module  720 , or a transmitter module  730 . Each of these components may be in communication with each other. 
     The components of the device  135 - c  may, individually or collectively, be implemented using one or more ASICs adapted to perform some or all of the applicable functions in hardware. Alternatively, the functions may be performed by one or more other processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., Structured/Platform ASICs, FPGAs, a SoC, and/or other types of Semi-Custom ICs), which may be programmed in any manner known in the art. The functions of each module may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by one or more general or application-specific processors. 
     In some examples, the receiver module  710  may include at least one RF receiver. The receiver module  710  or RF receiver may be used to receive various types of data or control signals (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system  100  described with reference to  FIG. 1 . In some examples, the transmissions may include D2D communications and/or LTE/LTE-A communications. 
     In some examples, the transmitter module  730  may include at least one RF transmitter. The transmitter module  730  or RF transmitter may be used to transmit various types of data or control signals (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system  100  described with reference to  FIG. 1 . In some examples, the transmissions may include D2D communications and/or LTE/LTE-A communications. 
     The wireless communication management module  720  may be used to manage one or more aspects of wireless communication for the device  135 - c.  In some examples, the wireless communication management module  720  may include a PRI management module  735 , a ProSe discovery message transmission management module  740 , or a relay connection management module  745 . 
     The PRI management module  735  may be used to receive, from a network, a PRI. In some examples, the PRI may be received from a base station operating as a serving cell for a ProSe relay candidate including the device  135 - c.  In some examples, the PRI may be received in a SIB or a unicast RRC message. 
     The ProSe discovery message transmission management module  740  may be used to broadcast at least one ProSe discovery message that includes the PRI (e.g., in accordance with PC5-D discovery techniques). In some examples, the at least one ProSe discovery message may include a relay offer message and/or an MBMS relay information message. In some examples, the relay offer message may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a relay-to-network RSRP, a relay-to-network RSRQ, the PRI, or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message may identify MBMSs offered by the ProSe relay candidate. 
     The relay connection management module  745  may be used to receive a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. 
       FIG. 8  shows a block diagram  800  of a device  135 - d  for use in wireless communication, in accordance with various aspects of the present disclosure. The device  135 - d  may be an example of aspects of one or more of the ProSe relay candidates or devices  135  described with reference to  FIG. 1, 2 , or  7 . The device  135 - d  may also be or include a processor. The device  135 - d  may include a receiver module  710 - a,  a wireless communication management module  720 - a,  or a transmitter module  730 - a,  which may be respective examples of the receiver module  710 , the wireless communication management module  720 , and the transmitter module  730  described with reference to  FIG. 7 . Each of these components may be in communication with each other. 
     The components of the device  135 - d  may, individually or collectively, be implemented using one or more ASICs adapted to perform some or all of the applicable functions in hardware. Alternatively, the functions may be performed by one or more other processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., Structured/Platform ASICs, FPGAs, a SoC, and/or other types of Semi-Custom ICs), which may be programmed in any manner known in the art. The functions of each module may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by one or more general or application-specific processors. 
     The wireless communication management module  720 - a  may be used to manage one or more aspects of wireless communication for the device  135 - d.  In some examples, the wireless communication management module  720 - a  may include a network communications management module  835 , a PRI management module  735 - a,  a measurement management module  840 , a ProSe discovery message transmission management module  740 - a,  or a relay connection management module  745 - a.    
     The network communications management module  835  may be used to communicate with a network (e.g., with a base station of a network that operates as a serving cell for a ProSe relay candidate including the device  135 - d ). 
     The PRI management module  735 - a  may be used to receive, from a network, a PRI. In some examples, the PRI may be received from the base station that operates as the serving cell for the ProSe relay candidate including the device  135 - d.  In some examples, the PRI may be received in a SIB or a unicast RRC message. 
     The measurement management module  840  may be used to measure a relay-to-network RSRP, a relay-to-network RSRQ, or a combination thereof. 
     The ProSe discovery message transmission management module  740 - a  may be used to broadcast at least one ProSe discovery message that includes the PRI (e.g., in accordance with PC5-D discovery techniques). In some examples, the at least one ProSe discovery message may include a relay offer message and/or an MBMS relay information message. In some examples, the relay offer message may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, an indicator of the measured relay-to-network RSRP, an indicator of the measured relay-to-network RSRQ, the PRI, or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message may identify MBMSs offered by the ProSe relay candidate. 
     The relay connection management module  745 - a  may be used to receive a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. 
       FIG. 9  shows a block diagram  900  of a UE  115 - e  for use in wireless communication, in accordance with various aspects of the present disclosure. The UE  115 - e  may have various configurations and may be a wireless communication device, a personal computer (e.g., a laptop computer, a netbook computer, a tablet computer, etc.), a handheld device, a cellular telephone, a smart phone, a cordless phone, a wireless modem, a wireless local loop (WLL) station, a personal digital assistant (PDA), a digital video recorder (DVR), an internet appliance, a gaming console, an e-reader, etc. The UE  115 - e  may, in some examples, have an internal power supply (not shown), such as a small battery, to facilitate mobile operation. In some examples, the UE  115 - e  may be an example of aspects of one or more of the UEs or devices  115  described with reference to  FIG. 1, 2, 5 , or  6 . The UE  115 - e  may be configured to implement at least some of the UE or device features and functions described with reference to  FIGS. 1-6 . 
     The UE  115 - e  may include a UE processor module  910 , a UE memory module  920 , at least one UE transceiver module (represented by UE transceiver module(s)  930 ), at least one UE antenna (represented by UE antenna(s)  940 ), or a UE wireless communication management module  520 - b.  Each of these components may be in communication with each other, directly or indirectly, over one or more buses  935 . 
     The UE memory module  920  may include random access memory (RAM) or read-only memory (ROM). The UE memory module  920  may store computer-readable, computer-executable code  925  containing instructions that are configured to, when executed, cause the UE processor module  910  to perform various functions described herein related to wireless communication, including, for example, evaluating ProSe discovery messages received from each of a plurality of ProSe relay candidates with respect to a relay selection rule, selecting one of the ProSe relay candidates, and connecting to a network via the selected ProSe relay candidate. Alternatively, the code  925  may not be directly executable by the UE processor module  910  but be configured to cause the UE  115 - e  (e.g., when compiled and executed) to perform various of the functions described herein. 
     The UE processor module  910  may include an intelligent hardware device, e.g., a central processing unit (CPU), a microcontroller, an ASIC, etc. The UE processor module  910  may process information received through the UE transceiver module(s)  930  or information to be sent to the UE transceiver module(s)  930  for transmission through the UE antenna(s)  940 . The UE processor module  910  may handle, alone or in connection with the UE wireless communication management module  520 - b,  various aspects of communicating over (or managing communications over) one or more communication links established with a ProSe relay candidate and/or one or more communication links with a base station. 
     The UE transceiver module(s)  930  may include a modem configured to modulate packets and provide the modulated packets to the UE antenna(s)  940  for transmission, and to demodulate packets received from the UE antenna(s)  940 . The UE transceiver module(s)  930  may, in some examples, be implemented as one or more UE transmitter modules and one or more separate UE receiver modules. The UE transceiver module(s)  930  may support communications over one or more wireless channels. The UE transceiver module(s)  930  may be configured to communicate bi-directionally, via the UE antenna(s)  940 , with one or more ProSe relay candidates, base stations, or other devices, such as one or more of the ProSe relay candidates  135 , base stations  105 , or devices  135  described with reference to  FIG. 1, 2, 7 , or  8 . While the UE  115 - e  may include a single UE antenna, there may be examples in which the UE  115 - e  may include multiple UE antennas  940 . 
     The UE wireless communication management module  520 - b  may be configured to perform or control some or all of the UE or device features or functions described with reference to  FIGS. 1-6  related to connecting to a network via a ProSe relay candidate. The UE wireless communication management module  520 - b,  or portions of it, may include a processor, or some or all of the functions of the UE wireless communication management module  520 - b  may be performed by the UE processor module  910  or in connection with the UE processor module  910 . In some examples, the UE wireless communication management module  520 - b  may be an example of the wireless communication management module  520  described with reference to  FIG. 5 or 6 . 
       FIG. 10  shows a block diagram  1000  of a ProSe relay candidate  135 - e  for use in wireless communication, in accordance with various aspects of the present disclosure. The ProSe relay candidate  135 - e  may have various configurations, and in some examples may be a UE, such as one of the UEs  115  described with reference to  FIG. 1, 2, 5, 6 , or  9 . The ProSe relay candidate  135 - e  may, in some examples, have an internal power supply (not shown), such as a small battery, to facilitate mobile operation. In some examples, the ProSe relay candidate  135 - e  may be an example of aspects of one or more of the ProSe relay candidates or devices  135  described with reference to  FIG. 1, 2, 7 , or  8 . The ProSe relay candidate  135 - e  may be configured to implement at least some of the ProSe relay candidate or device features and functions described with reference to  FIGS. 1-4, 7, and 8 . 
     The ProSe relay candidate  135 - e  may include a relay processor module  1010 , a relay memory module  1020 , at least one relay transceiver module (represented by relay transceiver module(s)  1030 ), at least one relay antenna (represented by relay antenna(s)  1040 ), or a relay wireless communication management module  720 - b.  Each of these components may be in communication with each other, directly or indirectly, over one or more buses  1035 . 
     The relay memory module  1020  may include RAM or ROM. The relay memory module  1020  may store computer-readable, computer-executable code  1025  containing instructions that are configured to, when executed, cause the relay processor module  1010  to perform various functions described herein related to wireless communication, including, for example, broadcasting at least one ProSe discovery message that includes a PRI, and providing relay services for one or more UEs based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of each UE. Alternatively, the code  1025  may not be directly executable by the relay processor module  1010  but be configured to cause the ProSe relay candidate  135 - e  (e.g., when compiled and executed) to perform various of the functions described herein. 
     The relay processor module  1010  may include an intelligent hardware device, e.g., a CPU, a microcontroller, an ASIC, etc. The relay processor module  1010  may process information received through the relay transceiver module(s)  1030  or information to be sent to the relay transceiver module(s)  1030  for transmission through the relay antenna(s)  1040 . The relay processor module  1010  may handle, alone or in connection with the relay wireless communication management module  720 - b,  various aspects of communicating over (or managing communications over) one or more communication links established with one or more UEs and one or more communication links established with a base station. 
     The relay transceiver module(s)  1030  may include a modem configured to modulate packets and provide the modulated packets to the relay antenna(s)  1040  for transmission, and to demodulate packets received from the relay antenna(s)  1040 . The relay transceiver module(s)  1030  may, in some examples, be implemented as one or more relay transmitter modules and one or more separate relay receiver modules. The relay transceiver module(s)  1030  may support communications over one or more wireless channels. The relay transceiver module(s)  1030  may be configured to communicate bi-directionally, via the relay antenna(s)  1040 , with one or more UEs, base stations, or other devices, such as one or more of the UEs  115 , base stations  105 , or devices  115  described with reference to  FIG. 1, 2, 5 , or  6 . While the ProSe relay candidate  135 - e  may include a single relay antenna, there may be examples in which the ProSe relay candidate  135 - e  may include multiple relay antennas  1040 . 
     The relay wireless communication management module  720 - b  may be configured to perform or control some or all of the ProSe relay candidate or device features or functions described with reference to  FIGS. 1-4, 7, and 8  related to connecting a UE to a network via the ProSe relay candidate  135 - e.  The relay wireless communication management module  720 - b,  or portions of it, may include a processor, or some or all of the functions of the relay wireless communication management module  720 - b  may be performed by the relay processor module  1010  or in connection with the relay processor module  1010 . In some examples, the relay wireless communication management module  720 - b  may be an example of the wireless communication management module  720  described with reference to  FIG. 7 or 8 . 
       FIG. 11  is a flow chart illustrating an exemplary method  1100  for wireless communication at a UE, in accordance with various aspects of the present disclosure. For clarity, the method  1100  is described below with reference to aspects of one or more of the UEs or devices  115  described with reference to  FIG. 1, 2, 5, 6 , or  9 . In some examples, a UE or device may execute one or more sets of codes to control the functional elements of the UE or device to perform the functions described below. Additionally or alternatively, the UE or device may perform one or more of the functions described below using special-purpose hardware. 
     At block  1105 , a UE may be configured with a relay selection rule. In some examples, the relay selection rule may be received from a ProSe function that configures the UE in accordance with the relay selection rule (e.g., configures the UE to evaluate the relay selection rule). In some examples, the ProSe function may be provided by a server (e.g., a server of the core network  130  described with reference to  FIG. 1 ). The operation(s) at block  1105  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the relay selection rule management module  535  described with reference to  FIG. 5 or 6 . 
     At block  1110 , the first UE may receive at least one ProSe discovery message from each of a plurality of ProSe relay candidates. Each of the ProSe relay candidates may provide access to a network. The operation(s) at block  1110  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 . 
     At block  1115 , the UE may evaluate the received ProSe discovery messages with respect to the relay selection rule. In some embodiments, the UE may evaluate the received ProSe discovery messages to identify one or more ProSe discovery messages that comply with the relay selection rule (e.g., the UE may identify a first ProSe discovery message of a first ProSe relay candidate, which first ProSe discovery message complies with the relay selection rule). In other embodiments, the UE may evaluate more than one (or all) of the received ProSe discovery messages and identify a ProSe discovery message received from one of the ProSe relay candidates (e.g., the first ProSe relay candidate) as complying with the relay selection rule to a greater extent than at least one other ProSe discovery message received from at least one other ProSe relay candidate. The UE may also identify a ProSe discovery message that complies with the relay selection rule better than any other discover message. The operation(s) at block  1115  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 . 
     At block  1120 , the UE may select a first ProSe relay candidate from the plurality of ProSe relay candidates based at least in part on the evaluating. The operation(s) at block  1120  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the ProSe relay candidate selection module  545  described with reference to  FIG. 5 or 6 . 
     At block  1125 , the UE may connect to the network via the first ProSe relay candidate. The operation(s) at block  1125  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the network connection management module  550  described with reference to  FIG. 5 or 6 . 
     Thus, the method  1100  may provide for wireless communication. It should be noted that the method  1100  is just one implementation and that the operations of the method  1100  may be rearranged or otherwise modified such that other implementations are possible. 
       FIG. 12  is a flow chart illustrating an exemplary method  1200  for wireless communication at a UE, in accordance with various aspects of the present disclosure. For clarity, the method  1200  is described below with reference to aspects of one or more of the UEs or devices  115  described with reference to  FIG. 1, 2, 5, 6 , or  9 . In some examples, a UE or device may execute one or more sets of codes to control the functional elements of the UE or device to perform the functions described below. Additionally or alternatively, the UE or device may perform one or more of the functions described below using special-purpose hardware. 
     At block  1205 , a UE may be configured with a relay selection rule. In some examples, the relay selection rule may be received from a ProSe function that configures the UE in accordance with the relay selection rule (e.g., configures the UE to evaluate the relay selection rule). In some examples, the ProSe function may be provided by a server (e.g., a server of the core network  130  described with reference to  FIG. 1 ). The operation(s) at block  1205  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the relay selection rule management module  535  described with reference to  FIG. 5 or 6 . 
     In some embodiments, the relay selection rule may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a threshold relay-to-network RSRP, a threshold relay-to-network RSRQ, a threshold relay-to-UE RSRP, a provisioned PRI indicating a relay selection policy for accessing a network, a radio validity condition, or a combination thereof. The radio validity condition may include a first radio validity condition indicating that each threshold condition of the at least one relay radio layer condition needs to be satisfied, or a second radio validity condition indicating that at least one threshold condition of the at least one relay radio layer condition needs to be satisfied. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof 
     At block  1210 , the first UE may receive at least one ProSe discovery message from a ProSe relay candidate. The ProSe relay candidate may provide access to a network. The operation(s) at block  1210  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 . 
     In some embodiments, the at least one ProSe discovery message may include a relay offer message and/or a MBMS relay information message. The relay offer message may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a relay-to-network RSRP, a relay-to-network RSRQ, a PRI of the ProSe relay candidate, or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message may identify MBMSs offered by the ProSe relay candidate. 
     At block  1215 , the UE may measure a relay-to-UE RSRP (e.g., a ProSe relay candidate-to-UE RSRP. The operation(s) at block  1215  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the measurement management module  635  described with reference to  FIG. 6 . 
     At blocks  1220 ,  1225 ,  1230 ,  1235 ,  1240 ,  1245 , and/or  1250 , the UE may evaluate the relay offer message with respect to the relay selection rule. By way of example, the method  1200  is configured to evaluate the at least one relay radio layer condition with respect to the relay selection rule first, and to evaluate the at least one upper layer condition with respect to the relay selection rule upon determining a compliance of the at least one relay radio layer condition with the relay selection rule. In an alternative embodiment, the method  1200  may be configured to evaluate the at least one upper layer condition with respect to the relay selection rule first, and to evaluate the at least one relay radio layer condition with respect to the relay selection rule upon determining a compliance of the at least one upper layer condition with the relay selection rule. 
     At block  1220 , the UE may perform a bitwise logical AND between the provisioned PRI of the relay selection rule and the PRI received in the relay offer message (e.g., in the ProSe discovery messages). At block  1225 , it may be determined whether the bitwise logical AND evaluated to TRUE. When it is determined that the bitwise logical AND evaluated to TRUE, the UE may consider the PRI to comply with the relay selection rule, and the method  1200  may continue at block  1230 . When it is determined that the bitwise logical AND evaluated to FALSE, the UE may consider the PRI to not comply with the relay selection rule, and the method  1200  may continue at block  1270 . The operation(s) at blocks  1220  and  1225  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 , or the relay offer message evaluation module  640  or PRI evaluation module  645  described with reference to  FIG. 6 . 
     At block  1230 , the UE may respectively compare a relay-to-network RSRP and relay-to-network RSRQ received in the relay offer message, if present, to a threshold relay-to-network RSRP and threshold relay-to-network RSRQ, if present, specified by the relay selection rule. When a value satisfies its threshold, the UE may consider the value to comply with the relay selection rule. When a value does not satisfy its threshold, the UE may consider the value to not comply with the relay selection rule. At block  1235 , the UE may compare the measured relay-to-UE RSRP to a threshold relay-to-UE RSRP, if present, specified by the relay selection rule. When the measured value satisfies the threshold, the UE may consider the measured value to comply with the relay selection rule. When the measured value does not satisfy the threshold, the UE may consider the measured value to not comply with the relay selection rule. 
     At block  1240 , the UE may determine whether a radio validity condition of the relay selection rule, if present, is satisfied. When it is determined that the radio validity condition is satisfied, the method  1200  may continue at block  1245 . When it is determined that the radio validity condition is not satisfied, the method  1200  may continue at block  1270 . The operation(s) at blocks  1230 ,  1235 , and  1240  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 , or the relay offer message evaluation module  640  or threshold condition evaluation module  650  described with reference to  FIG. 6 . 
     At block  1245 , the UE may compare the upper layer conditions indicated in the relay offer message to respective upper layer conditions specified by the relay selection rule, and at block  1250 , the UE may determine whether the upper layer conditions indicated in the relay offer message comply with the relay selection rule. When it is determined that the upper layer conditions indicated in the relay offer message comply with the relay selection rule, the method  1200  may continue at block  1255 . When it is determined that the upper layer conditions indicated in the relay offer message do not comply with the relay selection rule, the method  1200  may continue at block  1270 . The operation(s) at blocks  1245  and  1250  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 , or the relay offer message evaluation module  640  or upper layer condition evaluation module  655  described with reference to  FIG. 6 . 
     At block  1255 , the UE may determine whether the MBMS relay information message, if any, identifies at least one MBMS desired by the UE. When it is determined that the MBMS relay information message identifies at least one MBMS desired by the UE, the method  1200  may continue at block  1260 . When it is determined that the MBMS relay information message does not identify at least one MBMS desired by the UE, the method  1200  may continue at block  1270 . The operation(s) at block  1255  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , the ProSe discovery message processing module  540  described with reference to  FIG. 5 or 6 , or the MBMS relay information message evaluation module  660  described with reference to  FIG. 6 . 
     At block  1260 , the UE may select the ProSe relay candidate based at least in part on the evaluations performed at blocks  1220 ,  1225 ,  1230 ,  1235 ,  1240 ,  1245 , and/or  1250 , and based at least in part on the MBMS relay information message identifying the at least one MBMS desired by the UE (e.g., at block  1255 ). The operation(s) at block  1260  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the ProSe relay candidate selection module  545  described with reference to  FIG. 5 or 6 . 
     At block  1265 , the UE may connect to the network via the ProSe relay candidate. The operation(s) at block  1265  may be performed using the wireless communication management module  520  described with reference to  FIG. 5, 6 , or  9 , or the network connection management module  550  described with reference to  FIG. 5 or 6 . 
     At block  1270 , the UE may determine that the ProSe relay candidate is not a suitable ProSe relay candidate. If one or more other ProSe relay candidates are available, one or more additional ProSe relay candidates may be evaluated in accordance with the operations at blocks  1220 ,  1225 ,  1230 ,  1235 ,  1240 ,  1245 ,  1250 , and/or  1255 . 
     Thus, the method  1200  may provide for wireless communication. It should be noted that the method  1200  is just one implementation and that the operations of the method  1200  may be rearranged or otherwise modified such that other implementations are possible. 
     In some examples, aspects of the methods  1100  and  1200  described with reference to  FIGS. 11 and 12  may be combined. 
       FIG. 13  is a flow chart illustrating an exemplary method  1300  for wireless communication at a ProSe relay candidate, in accordance with various aspects of the present disclosure. For clarity, the method  1300  is described below with reference to aspects of one or more of the ProSe relay candidates or devices  135  described with reference to  FIG. 1, 2, 7, 8 , or  10 . In some examples, a ProSe relay candidate or device may execute one or more sets of codes to control the functional elements of the ProSe relay candidate or device to perform the functions described below. Additionally or alternatively, the ProSe relay candidate or device may perform one or more of the functions described below using special-purpose hardware. 
     At block  1305 , a ProSe relay candidate may receive, from a network, a PRI. In some examples, the PRI may be received from a base station operating as a serving cell for the ProSe relay candidate. In some examples, the PRI may be received in a SIB or a unicast RRC message. The operation(s) at block  1305  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the PRI management module  735  described with reference to  FIG. 7 or 8 . 
     At block  1310 , the ProSe relay candidate may broadcast at least one ProSe discovery message that includes the PRI (e.g., in accordance with PC5-D discovery techniques). In some examples, the at least one ProSe discovery message may include a relay offer message and/or an MBMS relay information message. In some examples, the relay offer message may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, a relay-to-network RSRP, a relay-to-network RSRQ, the PRI, or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message may identify MBMSs offered by the ProSe relay candidate. The operation(s) at block  1310  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the ProSe discovery message transmission management module  740  described with reference to  FIG. 7 or 8 . 
     At block  1315 , the ProSe relay candidate may receive a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. The operation(s) at block  1315  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the relay connection management module  745  described with reference to  FIG. 7 or 8 . 
     Thus, the method  1300  may provide for wireless communication. It should be noted that the method  1300  is just one implementation and that the operations of the method  1300  may be rearranged or otherwise modified such that other implementations are possible. 
       FIG. 14  is a flow chart illustrating an exemplary method  1400  for wireless communication at a ProSe relay candidate, in accordance with various aspects of the present disclosure. For clarity, the method  1400  is described below with reference to aspects of one or more of the ProSe relay candidates or devices  135  described with reference to  FIG. 1, 2, 7, 8 , or  10 . In some examples, a ProSe relay candidate or device may execute one or more sets of codes to control the functional elements of the ProSe relay candidate or device to perform the functions described below. Additionally or alternatively, the ProSe relay candidate or device may perform one or more of the functions described below using special-purpose hardware. 
     At block  1405 , a ProSe relay candidate may communicate with a network (e.g., with a base station of the network that operates as a serving cell for the ProSe relay candidate). The operation(s) at block  1405  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the network communications management module  835  described with reference to  FIG. 8 . 
     At block  1410 , the ProSe relay candidate may receive, from the network, a PRI. In some examples, the PRI may be received from the base station that operates as the serving cell for the ProSe relay candidate. In some examples, the PRI may be received in a SIB or a unicast RRC message. The operation(s) at block  1410  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the PRI management module  735  described with reference to  FIG. 7 or 8 . 
     At block  1415 , the ProSe relay candidate may measure a relay-to-network RSRP, a relay-to-network RSRQ, or a combination thereof. The operation(s) at block  1415  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the measurement management module  840  described with reference to  FIG. 8 . 
     At block  1420 , the ProSe relay candidate may broadcast at least one ProSe discovery message that includes the PRI (e.g., in accordance with PC5-D discovery techniques). In some examples, the at least one ProSe discovery message may include a relay offer message and/or an MBMS relay information message. In some examples, the relay offer message may include at least one relay radio layer condition and/or at least one upper layer condition. The relay radio condition(s) may include, for example, an indicator of the measured relay-to-network RSRP, an indicator of the measured relay-to-network RSRQ, the PRI, or a combination thereof. The upper layer condition(s) may include, for example, a PLMN ID, a ProSe Relay UE ID, relay connectivity information, relay status information, an indicator of service continuity support, or a combination thereof. The MBMS relay information message may identify MBMSs offered by the ProSe relay candidate. The operation(s) at block  1420  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the ProSe discovery message transmission management module  740  described with reference to  FIG. 7 or 8 . 
     At block  1425 , the ProSe relay candidate may receive a relay connection request from a UE based at least in part on a compliance of the at least one ProSe discovery message with a relay selection rule of the UE. The operation(s) at block  1425  may be performed using the wireless communication management module  720  described with reference to  FIG. 7, 8 , or  10 , or the relay connection management module  745  described with reference to  FIG. 7 or 8 . 
     Thus, the method  1400  may provide for wireless communication. It should be noted that the method  1400  is just one implementation and that the operations of the method  1400  may be rearranged or otherwise modified such that other implementations are possible. 
     Techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms “system” and “network” are often used interchangeably. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0 and A are commonly referred to as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1×EV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMTM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named 3GPP. CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description above, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description above, although the techniques are applicable beyond LTE/LTE-A applications. 
     The detailed description set forth above in connection with the appended drawings describes examples and does not represent all of the examples that may be implemented or that are within the scope of the claims. The terms “example” and “exemplary,” when used in this description, mean “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples. 
     Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. 
     The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. As used herein, including in the claims, the term “or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). 
     Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media can include RAM, ROM, EEPROM, flash memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media. 
     The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.