Apparatus, method, and computer-readable storage medium for UE-to-network relay initiation and configuration

Abstract

A technique for a relay user equipment (UE) is disclosed, which is operable to act as a relay between a remote UE and an eNodeB. The relay UE can receive a relay configuration message from the eNodeB, which includes one or more relay configuration parameters. The relay UE can identify relay UE information associated with one or more relay parameters of the relay UE. The relay UE can determine to act as a relay for the remote UE based on the one or more relay configuration parameters and the relay UE information. The relay UE can transmit a discovery message to the remote UE to establish a direct connection between the relay UE and the remote UE, wherein the relay UE is configured to relay data from the eNodeB to the remote UE through the direct connection between the relay UE and the remote UE.

Description

[0001] This application is a divisional application of a Chinese patent application with an international filing date of December 9, 2015, a national application number of 201580079978.4, and an invention title of "UE-to-Network Relay Initiation and Configuration". Background Art

[0002] Wireless mobile communication technologies use various standards and protocols to transfer data between nodes (e.g., transmission stations) and wireless devices (e.g., mobile devices). Some wireless devices communicate using orthogonal frequency division multiple access (OFDMA) in downlink (DL) transmissions and single-carrier frequency division multiple access (SC-FDMA) in uplink (UL) transmissions. Standards and protocols using orthogonal frequency division multiplexing (OFDM) for signal transmission include the 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE), the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (such as 802.16e, 802.16m), commonly known in the industry as WiMAX (Worldwide Interoperability for Microwave Access), and the IEEE 802.11 standard, commonly known in the industry as WiFi.

[0003] In a 3GPP radio access network (RAN) LTE system, a node can be a combination of an evolved universal terrestrial radio access network (E-UTRAN) Node B (commonly also denoted as evolved Node B, enhanced Node B, eNodeB, or eNB) and a radio network controller (RNC), which communicates with a wireless device called a user equipment (UE). A downlink (DL) transmission can be communication from a node (e.g., eNodeB) to a wireless device (e.g., UE), and an uplink (UL) transmission can be communication from a wireless device to a node. Brief Description of the Drawings

[0004] The features and advantages of the present disclosure will become readily apparent from the following detailed description in conjunction with the accompanying drawings, which illustrate the features of the present disclosure by way of example; and, wherein:

[0005] Figure 1 Shows a device-to-device (D2D) discovery and communication architecture according to an example;

[0006] Figure 2 Shows a relay user equipment (UE) acting as a relay between a remote UE and an eNodeB according to an example;

[0007] Figure 3 Is an abstract syntax notation (ASN) code describing a system information block (SIB) according to an example;

[0008] Figure 4Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0009] Figure 5 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0010] Figure 6 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0011] Figure 7 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0012] Figure 8 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0013] Figure 9 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0014] Figure 10 Is an Abstract Syntax Notation (ASN) code according to an example that describes a SideLink User Equipment (UE) Information Message;

[0015] Figure 11 Is an Abstract Syntax Notation (ASN) code according to an example that describes a SideLink User Equipment (UE) Relay Interest Indication Message;

[0016] Figure 12 Is an Abstract Syntax Notation (ASN) code according to an example that describes a Radio Resource Control (RRC) Connection Reconfiguration Message;

[0017] Figure 13 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0018] Figure 14 Shows signaling according to an example that enables a relay user equipment (UE) to act as a relay between an eNodeB and a remote UE;

[0019] Figure 15 Is an Abstract Syntax Notation (ASN) code according to an example that describes a SideLink Discovery Configuration Information Element (IE);

[0020] Figure 16is the Abstract Syntax Notation (ASN) code for the Side Link Discovery Configuration Information Element (IE) according to the example description;

[0021] Figure 17 Illustrates the relay reselection signaling according to the example;

[0022] Figure 18 Illustrates the relay reselection signaling according to the example;

[0023] Figure 19 Depicts the functionality of a Relay User Equipment (UE) operable to act as a relay between a remote UE and an eNodeB according to the example;

[0024] Figure 20 Depicts the functionality of a Relay User Equipment (UE) operable to act as a relay between a remote UE and an eNodeB according to the example;

[0025] Figure 21 Depicts the functionality of an eNodeB operable to indicate that a Relay User Equipment (UE) acts as a relay between an eNodeB and a remote UE according to the example;

[0026] Figure 22 Depicts the functionality of a remote User Equipment (UE) operable to communicate with an eNodeB via a relay UE according to the example;

[0027] Figure 23 Illustrates a diagram of a wireless device (e.g., UE) according to the example; and

[0028] Figure 24 Illustrates a diagram of a wireless device (e.g., UE) according to the example.

[0029] Now, reference will be made to the illustrated exemplary embodiments, and specific language will be used herein to describe them. However, it should be understood that no limitation of the scope of the technology is thereby intended. Detailed Description

[0030] Before disclosing and describing the present technology, it should be understood that the technology is not limited to the specific structures, processing actions, or materials disclosed herein, but extends to their equivalents as would be recognized by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing particular examples only and are not intended to be limiting. The same reference numerals in different drawings denote the same elements. Numbers are provided in the flowcharts and processes for clarity in showing actions and operations, and this does not necessarily indicate a particular order or sequence.

[0031] Example embodiments

[0032] A preliminary overview of the technical embodiments is provided below, and the specific technical embodiments are described in more detail hereinafter. This preliminary overview is intended to help the reader understand the technology more quickly, and is not intended to identify the key features or essential features of the technology, nor is it intended to limit the scope of the claimed subject matter.

[0033] Device-to-device (D2D) communication for evolved universal terrestrial radio access (E-UTRA) or Long Term Evolution (LTE) has been standardized since 3GPP LTE Release 12. The D2D feature enables direct communication of data between user equipment (UEs) through the cellular radio spectrum, but the data is not carried by the cellular network infrastructure. Within 3GPP, the D2D communication feature may be referred to as ProSe (Proximity Services) direct communication. In Releases 12 and 13, D2D is mainly targeted at public safety use cases. Thus, when there is no available LTE connection, public security personnel can use radio frequency (RF) communication to communicate with each other. In this use case, it is not dependent on network coverage. However, for future releases, commercial applications of D2D will also be considered.

[0034] In Release 12, some D2D features are covered, such as ProSe device-to-device discovery in network coverage. ProSe discovery refers to the process by which a UE uses E-UTRAN radio signals to detect and identify another nearby UE. Other D2D features include ProSe device-to-device broadcast communication and higher layer (e.g., access stratum (AS) layer) support to enable multicast (e.g., broadcast or multicast) and unicast above physical layer broadcast communication.

[0035] Figure 1 An exemplary device-to-device (D2D) discovery and communication architecture is shown. More specifically, Figure 1 A D2D / ProSe non-roaming reference architecture is shown. A first UE 102 may be connected to an E-UTRAN 110 through a first LTE-Uu interface, and a second UE 106 may be connected to the E-UTRAN 110 through a second LTE-Uu interface. The first UE 102 may execute a first ProSe application 104, and the second UE 106 may execute a second ProSe application 108. The first UE 102 and the second UE 106 may be connected through a PC5 interface. In other words, the PC5 interface is the communication link between two ProSe-capable UEs 102, 106 in direct communication.

[0036] In one example, the E-UTRAN 110 may be connected to the evolved packet core (EPC) 112 via the S1 interface. The EPC 112 may be connected to the ProSe function 114 via the PC4 interface, and the EPC 112 may be connected to the ProSe application server 116 via the SGi interface. The ProSe function 114 and the ProSe application server 116 may be connected via the PC2 interface. In addition, one of the UEs may be connected to the ProSe function 114 and the ProSe application server 116. For example, the second UE 106 may be connected to the ProSe function 114 via the PC3 interface, and the second ProSe application 108 executed on the second UE 106 may be connected to the ProSe application server 116 via the PC1 interface.

[0037] Release 13 aims to introduce enhancements to LTE D2D communication and discovery that meet the requirements for public safety for use in: (1) in-network coverage (intra-cell and inter-cell), (2) partial network coverage, and (3) out-of-network coverage scenarios. For non-public safety discovery, the enhancements to LTE D2D communication may be used for in-network coverage (intra-cell and inter-cell).

[0038] In addition, Release 13 aims to support the extension of network coverage using layer 3 (L3)-based ProSe UE-to-network relay. The ProSe UE-to-network relay may also be referred to as a relay UE. The relay UE may perform the function of ProSe UE-to-network relay, which supports the relay of unicast traffic to remote UEs not served by the E-UTRAN and the network. In other words, the relay UE may be used as a relay between the network and a remote UE outside the coverage area. The relay UE will be within the network coverage area, thus forwarding data to the remote UE outside the coverage area. The relay UE may relay unicast traffic in the uplink (UL) and downlink (DL). In other words, the relay UE may forward information from the remote UE to the network in the uplink and forward information from the network to the remote UE in the downlink. The relay UE may enhance the coverage of UEs outside the network. The relay UE may provide a general L3 forwarding function that may relay Internet Protocol (IP) traffic for public safety communications. In addition, the relay UE may relay IP traffic (e.g., voice data, video data) to support service continuity for remote UEs.

[0039] In one example, a network (e.g., an eNodeB) may control the initiation of ProSe UE-to-network relay features. The eNodeB may control the initiation of ProSe UE-to-network relay features for each cell or each relay UE or both. When the connection between the relay UE and the network is established, the relay UE may be initiated or configured to act as a relay. A given UE (i.e., the remote UE) may (re)select a relay UE and then a connection may be established between the remote UE and the relay UE. At this time, the relay UE may forward data from the network to the remote UE and vice versa.

[0040] As described in more detail below, the relay UE may be initiated and / or configured to act as a relay via the general network configuration in the system information block (SIB). The relay UE may determine to act as a relay based on a relay configuration message received from the network, or the network may use the relay configuration message to indicate to the relay UE to act as a relay. In other words, a given UE may determine to act as a relay UE or may be instructed to act as a relay UE. As described in more detail below, the remote UE may move from within the coverage area to outside the coverage area. In other words, the remote UE may initially be connected to the network, but after the remote UE moves out of the coverage area, the remote UE may connect to the relay UE and communicate with the network via the relay UE. The actions performed by the remote UE after moving out of the coverage area may be initiated by the remote UE or by the relay UE or the eNodeB. As described in more detail below, the relay UE may initiate a relay discovery and selection process to connect with the remote UE. In one example, the relay UE can act as a relay only when the network connection channel quality of the relay UE is higher than a defined threshold, and the remote UE can only perform the relay selection process when its network connection channel quality is lower than the defined threshold.

[0041] Figure 2An example of a relay user equipment (UE) 204 that acts as a relay between a remote UE 202 and an eNodeB 206 is shown. The eNodeB 206 may include one or more processors 207 and a memory 209. The relay UE 204 may also be referred to as a ProSe UE-to-network relay. The relay UE 204 may be connected to the eNodeB 206 via the Uu interface. Thus, the relay UE 204 may be within coverage relative to the network. The remote UE 202 may be outside the coverage. The remote UE 202 may not be directly connected to the eNodeB 206, but may be directly connected to the relay UE 204 via the PC5 interface. The relay UE 204 may act as an intermediary between the remote UE 202 outside the coverage and the eNodeB 206. The eNodeB 206 may be part of an evolved packet core (EPC) 208, and the eNodeB 206 may be connected to a public safety application server (AS) 210 via the SGi interface.

[0042] In one example, the relay UE 204 may be configured by the eNodeB 206 for relaying. The configured relay operations may include discovery and one-to-one communication between the relay UE 204 and the remote UE 202, or if the access stratum (AS) layer cannot distinguish whether a discovery message is being sent for a ProSe UE-to-network relay procedure or for another type of procedure (e.g., group member discovery), the configured relay operations may include only one-to-one communication. In one example, the following configuration may be sent by the access stratum (AS) layer because if the eNodeB 206 is to have strict control over these procedures, the eNodeB 206 may know that a given UE is initiating UE-to-network relay discovery before the message.

[0043] In one configuration, as part of initiating UE-to-network relay operations, the eNodeB 206 may broadcast a common network configuration message to multiple UEs. Specifically, the eNodeB 206 may broadcast a relay configuration information message that includes certain cell-specific information. The relay configuration information message may be part of a new system information block (SIB) broadcast from the eNodeB 206 to multiple UEs, or the relay configuration information message may be part of an existing SIB broadcast from the eNodeB 206 to multiple UEs. In one example, the relay configuration information message may include various common relay-related cell range configuration parameters (or relay configuration parameters), such as the s-relay parameter (threshold relay lower), the threshold relay upper parameter, the relay mobility configuration parameter, the initiaterelay from idle parameter, and the relay operation supported parameter.

[0044] In one example, the s-relay parameter (threshold relay lower) may represent a Uu link quality threshold above which a given UE can be used as a relay. In other words, a given UE may have a specific level of link quality to support acting as a relay for the remote UE 202. The Uu link quality threshold may be a reference signal received power (RSRP) and / or reference signal received quality (RSRQ) threshold. The s-relay parameter (threshold relay lower) can be used to ensure that UEs in poor coverage situations do not become relays, thus avoiding overusing cell resources to carry the relayed traffic between the eNodeB 206 and the relay UE 204. In one example, the s-relay parameter may be defined as thresholdLowRelayUE or discoveryThresholdLowRelayUE, or defined in a similar manner. The s-relay parameter may be a lower threshold above which a specific UE can be used as a relay, and the threshold upper parameter is such that below this parameter, a specific UE can be used as a relay, and above this parameter, a specific UE cannot be used as a relay. In other words, the s-relay parameter and the threshold upper parameter provide a range within which a specific UE can be used as a relay.

[0045] In one example, the threshold relay upper limit parameter may represent an upper threshold of the Uu link quality, above which a given UE cannot be used as a relay. The threshold relay upper limit parameter can be used to prevent a UE near the cell center from becoming a relay. A UE near the cell center is less likely to be used for the purpose of relaying traffic from a remote UE outside the coverage area, so resource usage and interference associated with discovery announcements can be avoided.

[0046] In one example, the relay mobility configuration parameter may represent an acceptable mobility state for a given UE to be used as a relay. For example, if the relay mobility configuration parameter is set to "low", this indicates that the given UE can be a low-mobility UE to be used as a relay.

[0047] In one example, the idle-initiated relay parameter can be set to "ON" or "OFF". When set to "ON", the UE can initiate relay operations while in the idle mode. Conversely, when set to "OFF", the UE may not be able to initiate relay operations while in the idle mode. In other words, when set to "OFF", the UE should enter the connected mode to initiate relay operations. Alternatively, instead of the idle-initiated relay parameter, if there is no relay configuration information and the eNodeB 206 supports relay operations, a given UE can implicitly assume going to the connected mode to enable relay operations.

[0048] In one example, the relay operation support parameter may represent whether the cell supports relay operations. For example, when the cell supports relay operations, the relay operation support parameter can be set to "yes", and conversely, when the cell does not support relay operations, the relay operation support parameter can be set to "no". The presence of parameters related to relay can also be an indication of relay operation support in the cell.

[0049] As described in further detail below, the eNodeB 206 can broadcast a relay configuration information message with relay configuration parameters to the relay UE 204. The relay configuration parameters can include the s-relay parameter (threshold relay lower limit), the threshold relay upper limit parameter, the relay mobility configuration parameter, the idle-initiated relay parameter, and the relay operation support parameter. Based on the relay configuration parameters included in the relay configuration information message, the relay UE 204 can decide to be used as a relay. Alternatively, after receiving the relay configuration parameters included in the relay configuration information message, the relay UE 204 can be instructed to be used as a relay. In other words, in the first scenario, the relay UE 204 decides to be used as a relay, and in the second scenario, the eNodeB 206 decides that the relay UE 204 is used as a relay.

[0050] Figure 3It is an exemplary Abstract Syntax Notation (ASN) code that describes a new type of System Information Block (SIB). The SIB can be broadcast from the eNodeB to the relay UE. The SIB can include relay operation support parameters. Additionally, the SIB can include a relay configuration information message containing several relay configuration parameters. The relay configuration parameters can include s-relay parameters (threshold relay lower limit), threshold relay upper limit parameters, relay mobility configuration parameters, and idle-initiated relay parameters.

[0051] Figure 4 Illustrates an exemplary relay initiation signaling that enables a relay User Equipment (UE) 420 to function as a relay between an eNodeB 430 and a remote UE 410. The eNodeB 430 can broadcast a relay configuration information message to the relay UE 420. The relay configuration information message can be included in System Information Block (SIB) 18, SIB 19, or another SIB. The relay configuration information message can include various relay configuration parameters, such as s-relay parameters (threshold relay lower limit), threshold relay upper limit parameters, relay mobility configuration parameters, and idle-initiated relay parameters.

[0052] Based on the relay configuration parameters (and UE internal information) included in the relay configuration information message, the relay UE 420 can determine whether to initiate the relay function. After the relay UE 420 determines to act as a relay, the relay UE 420 can send a discovery message to the remote UE 410. The discovery message can announce or proclaim that the relay UE 420 is acting as a relay and that the relay UE 420 is ready to receive direct communication requests from the remote UE 410. After transmitting the discovery message from the relay UE 420 to the remote UE 410, one-to-one communication can occur between the relay UE 420 and the remote UE 410. For example, the remote UE 410 can transmit a direct communication request message to the relay UE 420, and the remote UE 410 and the relay UE 420 can perform a mutual authentication process.

[0053] As Figure 4 shown, except for the setting of the broadcast configuration parameters, the eNodeB 430 does not participate in the relay UE's decision on whether to become a relay. In other words, the relay UE 420 autonomously decides whether to act as a relay based on the relay configuration parameters.

[0054] In one example, the relay UE 420 can determine whether to act as a relay based on UE internal information. The UE internal information can include measurements of serving cells (e.g., RSRP and / or RSRQ measurements) to be compared with thresholds provided as part of the relay configuration parameters. In other words, the relay UE 420 can compare its own measurements with the thresholds included in the s-relay parameter (threshold relay lower limit) and the threshold relay upper limit parameter, and based on this comparison, the relay UE 420 can determine whether to act as a relay. In one example, the UE internal information can include battery status information. For example, the relay UE 420 can decide to act as a relay only when the battery status of the relay UE is higher than a specific threshold, or when the relay UE 420 is connected to a permanent power source. In one example, the UE internal information can include user input information. For example, the relay UE 420 can decide to act as a relay only when the user / upper layer configures settings on the relay UE 420 to enable the relay function. Therefore, the relay UE 420 can use UE internal information in combination with relay configuration parameters when determining whether to act as a relay.

[0055] Figure 5 Exemplary relay initiation signaling that enables a relay user equipment (UE) 520 to act as a relay between an eNodeB 530 and a remote UE 510 is shown. The eNodeB 530 can broadcast a system information block (SIB) 18 or SIB 19 to the relay UE 520. In this configuration, the SIB 18 or SIB 19 may or may not include a relay configuration information message with relay configuration parameters. After the relay UE 520 receives the SIB 18 or SIB 19 from the eNodeB 530, the relay UE 520 transmits a discovery message to the remote UE 510. At this time, the relay UE 520 only sends the discovery message to initiate device-to-device (D2D) communication with the remote UE 510, and does not act as a relay for the remote UE 510. After transmitting the discovery message from the relay UE 520 to the remote UE 510, one-to-one communication can occur between the relay UE 520 and the remote UE 510. For example, the remote UE 510 can transmit a direct communication request message to the relay UE 520.

[0056] If the relay configuration is not broadcast in SIB 18 / 19, then at this time, the eNodeB 530 can broadcast a relay configuration message with relay configuration parameters to the relay UE 520 separately. Based on the relay configuration parameters and UE internal information, the relay UE 520 can determine whether to act as a relay for the remote UE 510. Additionally, the remote UE 510 and the relay UE 520 can perform a mutual authentication process. After the mutual authentication process, the relay UE 520 can act as a relay for the remote UE 510, or the relay UE 520 can just perform D2D communication with the remote UE 510 without acting as a relay.

[0057] Figure 4 and Figure 5 one difference between them is when the relay UE determines to act as a relay. In Figure 4 , the relay UE decides to act as a relay before sending the discovery message to the remote UE. For this option, if the discovery message is for the relay UE but the relay UE cannot perform relay operations according to the broadcast configuration of the eNodeB, the AS layer can reject the request from the upper layer. In Figure 5 , the relay UE can determine to act as a relay after sending the discovery message to the remote UE. In Figure 5 , if one-to-one communication is enabled, the AS layer can reject the request from the upper layer. In one example, from the perspective of the UE, the signaling shown in Figure 4 can be more beneficial because it can avoid advertisement / monitoring discovery messages from UEs that cannot perform UE-to-network relay operations.

[0058] Figure 6 FIG. shows exemplary relay initiation signaling that enables a relay user equipment (UE) 620 to act as a relay between an eNodeB 630 and a remote UE 610. The eNodeB 630 can broadcast a relay configuration information message to the relay UE 620. The relay configuration information message can be included in a system information block (SIB) 18, SIB 19, or another SIB. The relay configuration information message can include various relay configuration parameters, such as the s-relay (threshold relay lower limit) parameter, the threshold relay upper limit parameter, the relay mobility configuration parameter, and the idle-initiated relay parameter.

[0059] Based on the relay configuration parameters and UE internal information, the relay UE 620 can determine to act as a relay for the remote UE. The relay UE 620 can transmit a sidelink UE information message to the eNodeB 630, where the sidelink UE information message indicates the intention of the relay UE to act as a relay for the remote UE 610. In this configuration, the relay UE 620 makes the decision on whether to act as a relay, rather than the eNodeB 630 making the decision.

[0060] After the relay UE 620 determines to be used as a relay, the relay UE 620 may transmit a discovery message to the remote UE 610. The discovery message may announce that the relay UE 620 is being used as a relay and that the relay UE 620 is ready to receive direct communication requests from the remote UE 610. After transmitting the discovery message from the relay UE 620 to the remote UE 610, one-to-one communication may occur between the relay UE 620 and the remote UE 610. For example, the remote UE 610 may transmit a direct communication request message to the relay UE 620, and the remote UE 610 and the relay UE 620 may perform a mutual authentication process.

[0061] Figure 7 Exemplary relay-initiated signaling is shown that enables a relay user equipment (UE) 720 to be used as a relay between an eNodeB 730 and a remote UE 710. The eNodeB 730 may broadcast a relay configuration information message to the relay UE 720. The relay configuration information message may be included in System Information Block (SIB) 18, SIB 19, or another SIB. The relay configuration information message may include various relay configuration parameters, such as a s-relay parameter (threshold relay lower bound), a threshold relay upper bound parameter, a relay mobility configuration parameter, and an idle-initiated relay parameter.

[0062] The relay UE 720 may determine whether it is interested in being used as a relay based on the relay configuration parameters and UE internal information. The relay UE 720 may transmit a sidelink UE information message to the eNodeB 730, where the sidelink UE information message indicates whether the relay UE 720 is interested in being used as a relay. In this configuration, the relay UE 720 does not make a decision on whether to be used as a relay. Instead, the eNodeB 730 receives the sidelink UE information message with the relay UE's interest in being used as a relay, and then the eNodeB 730 makes a final determination on whether the relay UE 720 should have its relay function enabled. If the eNodeB 730 determines that the relay UE 720 is to be used as a relay, the eNodeB 730 may transmit a relay initiation and configuration message to the relay UE 720. The relay initiation and configuration message may be dedicated signaling specific to the relay UE 720 (i.e., not broadcast). In some cases, the eNodeB 730 may only send an acknowledgment (ACK) to the relay UE 720 indicating that the relay UE 720 is allowed to be used as a relay.

[0063] After receiving the relay initiation and configuration message (or ACK), the relay UE 720 may transmit a discovery message to the remote UE 710. The discovery message may announce that the relay UE 720 is operating as a relay and that the relay UE 720 is ready to receive direct communication requests from the remote UE. The remote UE 710 may transmit a direct communication request to the relay UE 720, and then the remote UE 710 and the relay UE 720 may perform a mutual authentication process.

[0064] In this configuration (i.e., when the eNodeB determines that the relay UE is operating as a relay), an increased amount of signaling overhead may occur. However, this approach enables the eNodeB to better control which UEs become relays. For example, the eNodeB may want to limit the number of UEs that become relays in order to reduce the overhead associated with the transmission of discovery messages from the relay UE.

[0065] Figure 8 An exemplary relay initiation signaling that enables a relay user equipment (UE) 820 to operate as a relay between an eNodeB 830 and a remote UE 810 is shown. The eNodeB 830 may broadcast a relay configuration information message to the relay UE 820. The relay configuration information message may be included in System Information Block (SIB) 18, SIB 19, or another SIB. The relay configuration information message may include various relay configuration parameters. At this time, the relay UE 820 may not be operating as a relay. The relay UE 820 may transmit a discovery message to the remote UE 810. The discovery message may be used to initiate Device-to-Device (D2D) communication between the relay UE 820 and the remote UE 810. The remote UE 810 may transmit a direct communication request to the relay UE 820.

[0066] After the discovery message and the direct communication request are transmitted, the relay UE 820 may send a sidelink UE information message to the eNodeB 830, where the sidelink UE information message indicates that the relay UE 820 is interested in operating as a relay. The eNodeB 830 may determine whether the relay UE 820 will operate as a relay, and if so, the eNodeB 830 may transmit a relay initiation and configuration message to the relay UE 820. The relay initiation and configuration message may be dedicated signaling specific to the relay UE 820 (i.e., not broadcast). Additionally, the remote UE 810 and the relay UE 820 may perform a mutual authentication process. At this time, the relay UE 820 may be configured to operate as a relay for the remote UE 810.

[0067] In this configuration, for each UE-to-network relay connection, or when the relay operation is actually initiated based on a direct communication request message rather than a discovery message, the relay UE 820 may have to obtain eNodeB authorization.

[0068] Figure 9 Exemplary relay initiation signaling is shown that enables relay user equipment (UE) 920 to act as a relay between eNodeB 930 and remote UE 910. The remote UE 910 can initially be within the coverage area of eNodeB 930. In other words, at least initially, a connection can be established between the remote UE 910 and eNodeB 930. The eNodeB 930 can broadcast a relay configuration information message to the relay UE 920. The relay configuration information message can be included in system information block (SIB) 18, SIB 19, or another SIB. The relay configuration information message can include various relay configuration parameters. At this time, the relay UE 920 may not act as a relay. The relay UE 920 can send a discovery message to the remote UE 910. The discovery message can be used to initiate D2D communication between the relay UE 920 and the remote UE 910.

[0069] In one example, the remote UE 910 can send a measurement report to the eNodeB 930 via a connection established between the remote UEs. Based on the measurement report, the eNodeB 930 can transmit a relay initiation and configuration message to the relay UE 920, which indicates that the relay UE 920 is to act as a relay for the remote UE 910. In other words, the eNodeB 930 can determine that the connection between the remote UE 910 and the eNodeB 930 is below a defined threshold based on the measurement report of the remote UE. Therefore, the eNodeB 930 can indicate that the relay UE 920 is to act as a relay via the relay initiation and configuration message, which can be dedicated signaling specific to the relay UE 920 (i.e., not broadcast). Since the relay UE 920 has already received the relay configuration information message with relay configuration parameters, the relay UE 920 can start acting as a relay for the remote UE 910 after receiving the relay initiation and configuration message from the eNodeB 930.

[0070] In one example, the eNodeB 930 can transmit a relay information message to the remote UE 910. The relay information message can indicate that the relay UE 920 is to act as a relay for the remote UE 910. The remote UE 910 can send a direct communication request to the relay UE 920. After a mutual authentication process is performed between the remote UE 910 and the relay UE 920, the relay UE 920 can act as a relay between the remote UE 910 and the eNodeB 930. At this time, the remote UE 910 can still be within the coverage area (although with a poor connection to the eNodeB 930), or the remote UE 910 can be outside the coverage area.

[0071] In one configuration, relay initiation can be performed dynamically at a given UE (e.g., a relay UE). The relay UE can determine whether to act as a relay based on relay configuration parameters received from the eNodeB and UE internal information. For example, if the relay UE determines that it meets various thresholds included in the relay configuration parameters, the relay UE can send dedicated signaling to the eNodeB to indicate that the relay UE is interested in acting as a relay. In other words, the relay UE can indicate an interest in acting as a relay and request the eNodeB to allow it to be used as a relay. The trigger for the relay UE to send a new message or piggyback the request to act as a relay using an existing message can be relay configured by the upper layer (e.g., when initiated from an application). However, in this case, even if the relay UE initiates the relay operation, the eNodeB still makes the final determination on whether to allow the relay UE to be used as a relay.

[0072] Figure 10 Is an exemplary Abstract Syntax Notation (ASN) code that describes a sidelink user equipment (UE) information message. The sidelink UE information message can be transmitted from the relay UE to the eNodeB. The sidelink UE information message can include a relay interest parameter that indicates whether the relay UE is interested in acting as a relay.

[0073] In one example, the sidelink UE information message can be an existing message used to convey D2D-related UE-specific information, and the sidelink UE information message can be reused for the purpose of UE-initiated relay operation. A given UE can send the sidelink UE information message to the eNodeB, where the sidelink UE information message includes a relay interest field. The relay interest field enables the given UE to indicate to the eNodeB an interest in acting as a relay UE (i.e., enabling its relay function). For example, if the conditions for the given UE to become a relay are met (e.g., based on relay configuration parameters and UE internal information included in the system information), the UE can include the relay interest field.

[0074] Figure 11 Is an exemplary Abstract Syntax Notation (ASN) code that describes a sidelink user equipment (UE) relay interest indication message. The sidelink UE relay interest indication message can be transmitted from the relay UE to the eNodeB. The sidelink UE relay interest indication message can include a relay interest parameter that indicates whether the relay UE is interested in acting as a relay.

[0075] In one example, a D2D-specific sidelink UE relay interest indication message can be used for the purpose of UE-initiated relay operations. The sidelink UE relay interest indication message can be a new message added to 3GPP LTE Technical Specification (TS) 36.331. A given UE can send the sidelink UE relay interest indication message to the eNodeB, where the sidelink UE relay interest indication message includes an indication of the UE's relay interest in the eNodeB. The sidelink UE relay interest indication message can be provided to the eNodeB at any time during which the UE is in the RRC connected mode.

[0076] In one example, the sidelink UE information message and the sidelink UE relay interest indication message can be similar to the sidelink UE information message transmitted from the relay UE to the eNodeB as described above with respect to Figure 7 and Figure 8 above.

[0077] As described in further detail below, after the eNodeB receives the sidelink UE information message or the sidelink UE relay interest indication message from the relay UE, the eNodeB can respond with appropriate relay configuration parameters. In other words, following UE relay initiation (where a given UE indicates an interest in relay operations) can be a UE-specific relay configuration transmitted from the eNodeB to the relay UE. The UE-specific relay configuration can be similar to the relay initiation and configuration message transmitted from the eNodeB to the relay UE as described above with respect to Figures 7-9 above. Additionally, the communication of the sidelink UE information message can allow for the adjustment of any radio resource management (RRM) parameters at the eNodeB (e.g., the eNodeB can consider moving the relay UE to a different frequency).

[0078] In one configuration, based on the sidelink UE information message received from the relay UE, the eNodeB can initiate the relay operation of the UE and provide UE-specific relay configuration information to the relay UE. The UE-specific relay configuration information can also be referred to as the relay initiation and configuration message.

[0079] In other scenarios, the eNodeB can transmit the relay initiation and configuration message to the relay UE in response to a request from a remote UE for the relay UE, or in response to a measurement report from a remote UE, as described above. In these scenarios, the relay UE may not send the sidelink UE information message to the eNodeB (which indicates an interest in acting as a relay). Instead, without any signaling from a given UE, the eNodeB can send the relay initiation and configuration message to the given UE, and the given UE can begin to act as a relay for the remote UE.

[0080] In one example, the relay initiation and configuration message can be transmitted from the eNodeB to the relay UE together with existing RRC messages. For example, the relay initiation and configuration message can be part of the RRC connection reconfiguration message sent from the eNodeB to the relay UE. Alternatively, the relay initiation and configuration message can be a new message transmitted from the eNodeB to the relay UE.

[0081] Figure 12 is an exemplary Abstract Syntax Notation (ASN) code that describes the Radio Resource Control (RRC) connection reconfiguration message. The RRC connection reconfiguration message can be transmitted from the eNodeB to the relay UE and is used to initiate the relay operation of the UE. When the eNodeB initiates the relay operation of the UE in the existing RRC connection reconfiguration message, the RRC connection reconfiguration message can include a sidelink relay configuration field. The sidelink relay configuration field can include various parameters, such as the sidelink relay discovery start (SLrelayDiscoveryStart) parameter, the relay discovery period (t_relayDiscoveryPeriodicity) parameter, the relay operation timer (t_relayOperationTimer) parameter, the sidelink maximum remote UEs (SLmaxRemoteUEs) parameter, the sidelink relay resource configuration (SLrelayResourceConfiguration) parameter, the sidelink remote UE authorization (SLremoteUEAuthorization) parameter, and the sidelink relay control configuration (SLrelayControlConfiguration) parameter. Based on the reception of these parameters, the relay UE can be configured to act as a relay for remote UEs.

[0082] In one example, the sidelink relay discovery start (SLrelayDiscoveryStart) parameter can configure the UE to act as a relay (i.e., enable its relay function). For example, the sidelink relay discovery start parameter can be set to "on". In response to receiving the sidelink relay discovery start parameter, the relay UE can initiate the transmission of a discovery announcement message to the remote UE for relay purposes.

[0083] In one example, the relay discovery period (t_relayDiscoveryPeriodicity) parameter can indicate the frequency of the relay discovery operation (e.g., a configurable timer). This parameter can indicate the period of the announcement process of the relay UE, where the relay UE performs the announcement process to announce itself as a relay. In one example, even if the period of the discovery message is defined in the upper layer, the Access Stratum (AS) layer can perform retransmission of the relay discovery period, for example, to increase the reliability of the discovery message.

[0084] In one example, the relay operation timer (t_relayOperationTimer) parameter may include a timer indicating how long the relay UE will act as a relay. Additionally, the timer may indicate the duration for which the eNodeB's authorization for the relay UE to act as a relay is valid. The relay UE may operate in the idle mode and the connected mode until the timer expires. In one example, the timer may have a longer duration depending on the network configuration.

[0085] In one example, the sidelink maximum remote UEs (SLmaxRemoteUEs) parameter may indicate the maximum number of remote UEs that the relay UE can support. In Release 12, the relay UE may receive up to 16 sidelink processes, which means that the relay UE is capable of supporting up to 16 remote UEs simultaneously. In some cases, the eNodeB may force the relay UE to support fewer remote UEs depending on the congestion and / or interference level.

[0086] In one example, the sidelink relay resource configuration (SLrelayResourceConfiguration) parameter may indicate the specific pool configuration information that the relay UE can use to communicate with the remote UEs, which may potentially result in power savings. For example, this parameter may provide the relay UE with specific detailed resource configurations, and the relay UE may share this information with the remote UEs, or the remote UEs within the coverage area may also obtain this configuration by broadcasting system information. This resource configuration may be used to announce sidelink discovery in the same cell or in a different frequency cell.

[0087] In one example, the sidelink remote UE authorization (SLremoteUEAuthorization) parameter may provide authorization for the remote UEs. If this parameter is set to "on", the relay UE does not have to forward the remote UE identifier (ID) to the eNodeB via a new sidelink message or an existing sidelink message. Therefore, the eNodeB does not have to explicitly authorize the remote UEs. In this case, the authentication between the remote UE and the relay UE, as well as the service level authorization of the remote UE, are sufficient.

[0088] In one example, the sidelink relay control configuration (SLrelayControlConfiguration) parameter may indicate that the relay UE releases or redirects the remote UEs. This may apply during the scenario from outside the coverage area to inside the coverage area. Based on this parameter, the eNodeB may provide the relay UE with control to be able to release the remote UEs or direct the remote UEs so that the eNodeB does not participate in the release or direction of the remote UEs. However, in some cases, the eNodeB may want to participate in more stringent control of the operations for the remote UE handover.

[0089] As described above, after the eNodeB transmits a relay initiation and configuration message with parameters (e.g., as part of an existing RRC message) to the relay UE, the relay UE can be configured to act as a relay for a remote UE. In other words, the relay UE can utilize these parameters to act as a relay for the remote UE. The relay initiation and configuration message can be a dedicated message (i.e., not broadcast) specifically transmitted to the relay UE.

[0090] In some cases, a given UE may not wish to be configured as a relay UE. For example, a given UE with a battery level below a defined threshold may wish not to act as a relay, even if the UE is authorized to act as a relay at the service level. In such a case, the UE may not initiate the relay operation on its own. In other words, the UE may not transmit a sidelink UE information message to the eNodeB that indicates an interest in acting as a relay. When the network initiates the UE to act as a relay (i.e., the UE has not expressed an interest in acting as a relay), a UE that cannot comply with the new configuration specified in the RRC connection reconfiguration message can continue to use the previous configuration (in accordance with the current specification).

[0091] In one configuration, the remote UE can switch from a connection with the eNodeB to a connection with the relay UE. For example, the remote UE can initially be connected to the eNodeB via the Uu interface. In other words, the remote UE can be within the coverage area of the eNodeB. During this period, the remote UE can monitor the connection link quality according to legacy behavior (i.e., the link quality of the Uu interface). If the connection link quality (or the serving channel quality) becomes less than the defined threshold, but the remote UE does not detect any neighboring cells for handover, the remote UE can perform a discovery process for relay UE selection. In other words, the remote UE can be searching for a relay UE. The discovery process can utilize Model A or Model B, as further described in 3GPP LTE Release 12. Once the remote UE discovers a relay UE neighboring the remote UE, the remote UE can select the relay UE based on the link quality.

[0092] In some cases, when the remote UE is within the coverage area and directly connected to the eNodeB, the remote UE may wish to be released from the direct connection with the eNodeB (i.e., the Uu connection) when communication with the relay UE has been established. After some time, the remote UE may become outside the coverage area of the eNodeB. These cases are further described in Figure 13 and Figure 14 below.

[0093] Figure 13Exemplary signaling is shown that enables relay user equipment (UE) 1320 to act as a relay between eNodeB 1330 and remote UE 1310. The eNodeB 1330 may broadcast a relay configuration information message to the relay UE 1320. The relay configuration information message may be included in system information block (SIB) 18, SIB 19, or another SIB. The relay UE 1320 and the remote UE 1310 may perform a discovery process. The relay UE 1320 may initiate the discovery process after determining to act as a relay based on the relay configuration information message received from the eNodeB 1330. Thereafter, the remote UE 1310 may send a direct communication request to the relay UE 1320, and the relay UE 1320 and the remote UE 1310 may perform a mutual authentication process. At this time, the remote UE 1310 and the relay UE 1320 may perform D2D communication with each other.

[0094] In one example, the remote UE 1310 may send a newly defined message or an existing message (e.g., a sidelink UE information message) to the eNodeB 1330 to notify the eNodeB 1330 that the remote UE 1310 has established a relay-based connection with the relay UE 1320. Since the remote UE 1310 is still within the coverage of the eNodeB 1330, the remote UE 1310 may transmit the sidelink UE information message. Additionally, the sidelink UE information message may indicate that the remote UE wishes to be released from direct communication with the eNodeB 1330. Accordingly, the connection (i.e., the Uu connection) between the remote UE 1310 and the eNodeB 1320 may be released, and the remote UE 1310 may connect only to the relay UE 1320. Thus, in this configuration, the release of the Uu connection may be initiated by the remote UE 1310.

[0095] Figure 14 Exemplary signaling is shown that enables relay user equipment (UE) 1420 to act as a relay between eNodeB 1430 and remote UE 1410. The eNodeB 1430 may broadcast a relay configuration information message to the relay UE 1420. The relay configuration information message may be included in system information block (SIB) 18, SIB 19, or another SIB. The relay UE 1420 and the remote UE 1410 may perform a discovery process. The relay UE 1420 may initiate the discovery process after determining to act as a relay based on the relay configuration information message received from the eNodeB 1430. Thereafter, the remote UE 1410 may send a direct communication request to the relay UE 1420, and the relay UE 1420 and the remote UE 1410 may perform a mutual authentication process. At this time, the remote UE 1410 and the relay UE 1420 may perform D2D communication with each other.

[0096] In one example, after establishing a connection with the remote UE 1410, the relay UE 1420 may send a newly defined dedicated side-link message or an existing side-link UE information message to the eNodeB 1430, where the message may include information about the connection of the relay UE to the remote UE. Specifically, the message may include the specific identifier (ID) of the remote UE connected to the relay UE 1420. Based on this information, the eNodeB 1430 may perform an RRC connection release on the remote UE 1410. In other words, the eNodeB 1430 may release the Uu connection with the remote UE 1410. Thus, in this configuration, the release of the Uu connection may be initiated by the relay UE 1420 and / or the eNodeB 1430, rather than by the remote UE 1410.

[0097] In one configuration, the remote UE may move from outside the coverage of the eNodeB to within the coverage of the eNodeB. The remote UE may establish a direct connection with the eNodeB using legacy procedures. In other words, after the remote UE is in a suitable cell, the remote UE may perform an RRC connection establishment procedure to establish a direct connection with the eNodeB. When outside the coverage, the remote UE may have been connected to the relay UE. In some cases, after establishing a direct connection with the eNodeB, the remote UE may terminate the connection with the relay UE (i.e., stop the UE-to-network relay function). For example, after the remote UE detects any cell that meets the S criteria, the remote UE may abort using the relay UE as a relay, as defined in Section 5.2.3.2 of 3GPP TS 36.304. In another example, after the remote UE finds a suitable cell or a cell in limited service, the remote UE may abort using the relay UE as a relay. In yet another example, the remote UE may interrupt using the relay UE as a relay after the remote UE successfully establishes an RRC connection, sends an RRC connection request, or establishes an EPS bearer for an application previously served by the relay UE.

[0098] In one example, the relay UE may redirect the remote UE to establish a direct Uu connection with the eNodeB because the relay UE has access to both the PC5 interface (i.e., the interface between the relay UE and the remote UE) and Uu link quality measurements (i.e., the link quality measurements between the relay UE and the eNodeB). In this case, if the relay UE determines that the PC5 link quality is higher than a specific upper threshold, the relay UE may recommend or initiate the remote UE to perform cell detection / measurement for establishing a direct link connection with the eNodeB. Once the remote UE has established communication with the eNodeB, the remote UE may request the relay UE to be released on the relay link for a smooth transition.

[0099] In one configuration, a remote UE may initiate relay discovery and selection. In other words, a UE with ProSe capabilities within coverage may initiate a relay discovery process. In a first scenario, the eNodeB may receive a measurement report (e.g., a report with RSRP and / or RSRQ measurements) from the remote UE, and if the measurement report indicates that the Uu link quality is below a specific threshold, the eNodeB may trigger the discovery process in the remote UE. In a second scenario, the remote UE may trigger the relay discovery process on its own based on thresholds announced in dedicated signaling or system information.

[0100] In one example, since the remote UE will continue to maintain the Uu connection until relay communication is determined and established, these thresholds may be set to more conservative values compared to the S-criterion threshold defined for the legacy cell selection process in LTE. The remote UE may support operations on both the PC5 interface with the relay UE and the Uu connection with the eNodeB simultaneously.

[0101] As mentioned before, the remote UE may trigger the relay discovery process on its own based on thresholds announced in dedicated signaling or system information. In one example, these thresholds may be transmitted to the remote UE via a sidelink discovery configuration information element (IE). The sidelink discovery configuration IE may be transmitted from the eNodeB to the remote UE in SIB 18, SIB 19, or an RRC connection reconfiguration message. Based on the thresholds included in the sidelink discovery configuration IE, the remote UE may initiate a discovery process to identify relay UEs located near the remote UE. In another example, these thresholds may be provided, where the S-criterion threshold is provided within a system information message (e.g., SIB3), which is a trigger for in-cell / inter-cell search.

[0102] Figure 15 and Figure 16It is an exemplary Abstract Syntax Notation (ASN) code that describes the side link discovery configuration information element (IE). The side link discovery configuration IE (IE SL-DiscConfig) can be transmitted from the eNodeB to the remote UE. More specifically, the side link discovery configuration IE can be transmitted via SIB 18, SIB 19, or RRC connection reconfiguration or side link UE information message. The side link discovery configuration IE can include various measurement thresholds, which can be used by the remote UE to perform the relay discovery process. For example, the remote UE can compare its own measurements (e.g., RSRP or RSRQ measurements) with the measurement thresholds, and based on this comparison, the remote UE can perform the relay discovery process and further perform relay communication. In other words, if the link quality between the remote UE and the eNodeB is less than the defined threshold, the remote UE can initiate the relay discovery process to identify a given UE that serves as a relay between the eNodeB and the remote UE. The relaySelectionInfo parameter can also be interpreted as the cell selection information broadcast by the serving cell in SIB19, which the remote UE will use to select a cell on another frequency.

[0103] In one example, when the remote UE is still within the coverage area of the eNodeB, another type of dedicated signaling message can be used to provide the above configuration information from the eNodeB to the remote UE.

[0104] In one configuration, a remote UE outside the coverage area (or a UE with ProSe function) can initiate relay discovery and selection. In this scenario, the technology used by the remote UE outside the coverage area can be the responsibility of the UE implementation.

[0105] In one configuration, the relay UE can be associated with a specific RRC state during the discovery phase and the one-to-one communication phase. During the discovery phase, the relay UE may not have any ongoing data activity on either the PC5 interface or the Uu interface. During the discovery phase, even when the relay UE is in the RRC idle mode, the relay UE is allowed to perform discovery (if the advertisement of the discovery message is based on Model A). If the eNodeB requires the relay UE to obtain eNodeB authorization for discovery due to relay operation, the relay UE can initiate RRC connection establishment. Similar to the discovery process in Release 12, if the eNodeB allocates discovery resources via dedicated signaling, the UE should be in the connected mode to receive the discovery resource configuration. If Discovery Process Model B is used, the relay UE should only monitor the discovery message. In this case, the relay UE can remain in the idle mode. During the one-to-one communication phase, in order to route data to the network, the relay UE should be in the connected mode.

[0106] In one configuration, relay reselection signaling optimization can be implemented. In Release 12, when an eNodeB receives a connection establishment request from a UE with ProSe capabilities (i.e., a remote UE), it must obtain the ProSe UE context from the core network. For example, the eNodeB can obtain the ProSe UE context from the core network via the Mobility Management Entity (MME), Home Subscriber Server (HSS), and / or ProSe capabilities. In Release 13, if a remote UE uses a relay UE for communication and is to be authorized by the eNodeB for each relay reselection within the same eNodeB coverage area, this can lead to an increase in signaling overhead and latency.

[0107] In one example, if eNodeB authorization is expected for a remote UE outside the coverage area, the relay UE can forward the remote UE ID to the eNodeB. The remote UE ID can be the International Mobile Subscriber Identity (IMSI), ProSe UE ID, or link layer ID. After the relay UE forwards the remote UE to the eNodeB, the eNodeB can obtain the ProSe UE context from the core network. Then, the eNodeB can store the ProSe UE context (specifically for the remote UE) for a defined period of time such that the ProSe UE context can be reused during relay reselection.

[0108] Figure 17 An exemplary relay reselection signaling is shown. More specifically, a relay selection process can be performed where the eNodeB 1730 retrieves the ProSe UE context from the core network (CN). The ProSe UE context can be associated with the remote UE 1710. The retrieval of the ProSe UE context can involve multiple nodes in the CN, such as the Mobility Management Entity (MME) 1740, Home Subscriber Server (HSS) 1750, and ProSe capabilities 1760.

[0109] In one example, an initial E-UTRAN attachment and / or a UE-requested Packet Data Network (PDN) connection can be performed. The remote UE 1710 can perform a relay discovery process with the relay UE 1720, where the relay discovery process is according to Model A or Model B. The remote UE 1710 can transmit a direct communication request message to the relay UE 1720. The relay UE 1720 can transmit an RRC message (e.g., a sidelink UE information message) to the eNodeB 1730, where the RRC message includes the remote UE ID. The eNodeB 1730 can perform ProSe authorization processing for the remote UE 1710 based on the subscription. During this processing, the eNodeB 1730 can retrieve the remote UE context information from the core network (i.e., the MME 1740, the HSS 1750, and the ProSe function 1760). The eNodeB 1730 can transmit an RRC message response to the relay UE 1720, where the RRC message response includes the remote UE ID. Additionally, the relay UE 1720 can transmit a direct communication response message to the remote UE 1710.

[0110] Figure 18 An exemplary relay reselection signaling is shown. More specifically, a relay selection process can be performed, where the eNodeB 1830 retrieves the stored ProSe UE context. The ProSe UE context can be associated with the remote UE 1810. In this configuration, the eNodeB 1830 does not have to retrieve the ProSe UE context from the core network (CN), where the CN includes the Mobility Management Entity (MME) 1840, the Home Subscriber Server (HSS) 1850, and the ProSe function 1860.

[0111] In one example, an initial E-UTRAN attachment and / or a UE-requested Packet Data Network (PDN) connection can be performed. The remote UE 1810 can perform a relay discovery process with the relay UE 1820, where the relay discovery process is according to Model A or Model B. The remote UE 1810 can transmit a direct communication request message to the relay UE 1820. The relay UE 1820 can transmit an RRC message (e.g., a sidelink UE information message) to the eNodeB 1830, where the RRC message includes the remote UE ID. In this configuration, the eNodeB 1830 does not perform ProSe authorization processing for the remote UE 1810 based on the subscription. Instead, since the remote UE context information is already stored at the eNodeB 830, the eNodeB 1830 can transmit an RRC message response to the relay UE 1820, where the RRC message response includes the remote UE ID. Additionally, the relay UE 1820 can transmit a direct communication response message to the remote UE 1810.

[0112] As described above, when the remote UE is not connected to the eNodeB, the relay UE can be used as a relay between the remote UE and the eNodeB. In one configuration, the remote UE can be associated with the following features: (1) The remote UE can have ProSe capabilities and be able to communicate with the eNodeB either directly or through the relay UE (also known as UE-to-network relay). (2) The remote UE can directly transmit a sidelink UE information message or a newly defined message to the eNodeB to notify the eNodeB that the remote UE has identified a relay UE for communication and thus the remote UE wishes to release from direct communication with the eNodeB. (3) If the remote UE detects a cell that meets the S criterion, detects a suitable cell, or establishes a connection with the eNodeB, the remote UE can stop using the relay UE for communication. (4) The remote UE can receive a command from the relay UE to switch to a direct connection with the relay UE. (5) The remote UE can trigger a relay discovery process based on a command from the eNodeB. (6) The remote UE can trigger the relay discovery process by itself using a broadcast link quality threshold and its own measurements. (7) The remote UE can receive the link quality threshold and the relay initiation command through system information or dedicated signaling.

[0113] In one configuration, the relay UE can be associated with the following features: (1) The relay UE can support ProSe D2D communication as well as the relay operation as a UE-to-network relay to send or receive communication from the eNodeB on one side and other remote UEs on the other side. (2) The relay UE can receive the broadcast of certain relay configuration-related parameters. The broadcast can be in the existing or new system information. These parameters can include threshold parameters representing the link quality measurement between the relay UE and the remote UE, mobility state parameters that the relay UE should meet, and a parameter indicating whether the relay UE supports acting as a relay from the idle or connected mode. (3) The relay UE can send a dedicated sidelink UE relay interest indication message to the eNodeB. (4) The relay UE can receive relay initiation and configuration within the'sl-RelayConfig-r13' field. The relay initiation and configuration can be included in the RRC connection reconfiguration message received from the eNodeB, a new unicast or broadcast, or an existing or new system information message.

[0114] In addition, the relay UE in (5) can process and apply the following configuration parameters: SLrelayDiscoveryStart (for starting the discovery process of the relay UE), t_relayDiscoveryPeriodicity (for specifying the frequency of relay announcements), t_relayOperationTimer (the validity of relay operation), SLmaxRemoteUEs (the number of UEs that can be connected by the relay UE), SLrelayResourceConfiguration (specific pool configuration information), SLremoteUEAuthorization (whether a remote UE can be authorized by the relay UE itself), and SLrelayControlConfiguration (whether the relay UE can release / redirect a remote UE by itself). (6) The relay UE can decide to act as a relay based on internal information such as serving cell measurements (compared with provided thresholds), battery status information, and user input information. (7) When receiving configuration parameters from the eNodeB, the relay UE can decide to act as a relay.

[0115] In addition, the relay UE in (8) can process communication request messages from remote UEs and initiate relay processing if the relay processing has not been configured by the eNodeB using existing messages (e.g., SidelinkUEinformation) or newly defined messages. (9) Once the remote UE connection is established, the relay UE can send remote UE information (e.g., remote UE ID) in newly defined messages or existing messages. (10) The relay UE can recommend that a remote UE switch its connection from relay to direct communication based on PC5 and Uu link quality measurements and thresholds. (11) The relay UE can determine whether eNodeB authorization is required and initiate an RRC connection establishment process before performing the relay discovery process. (12) The remote UE can receive remote UE information (e.g., eNodeB authorization, context information) in newly defined messages or existing messages to complete the remote UE one-to-one connection.

[0116] In one configuration, the eNodeB may be associated with the following features: (1) The eNodeB (or a similar network node) may support ProSe D2D multicast and unicast communications as well as relay operations. The eNodeB may configure certain UEs to be used as UE-to-network relays and send or receive communications from these relays. (2) The eNodeB may broadcast certain relay configuration-related parameters. The broadcast may be performed in the existing or new system information. These parameters may include threshold parameters representing link quality measurements between the relay UE and the eNodeB, mobility status parameters that the relay UE should meet, and parameters indicating whether the relay UE supports being used as a relay from the idle or connected mode. (3) The eNodeB may receive a Sidelink UE Information message with an indication of interest for a given UE to be used as a relay. (4) The eNodeB may receive a SideLink UE Relay Interest Indication message. (5) The eNodeB may send relay initiation and configuration within the'sl-RelayConfig-rl3' field. The relay initiation and configuration may be included in an RRC connection reconfiguration message received from the eNodeB, a new unicast or broadcast, or an existing or new system information message.

[0117] In addition, (6) the configuration parameters may include the following: SLrelayDiscoveryStart (for starting the discovery process of the relay UE), t_relayDiscoveryPeriodicity (for specifying the frequency of relay announcements), t_relayOperationTimer (validity of relay operations), SLmaxRemoteUEs (the number of UEs that can be connected by the relay UE), SLrelayResourceConfiguration (specific pool configuration information), SLremoteUEAuthorization (whether a remote UE can be authorized by the relay UE itself), and SLrelayControlConfiguration (whether the relay UE can release / redirect a remote UE by itself).

[0118] In addition, (7) once a remote UE connection is established via a relay UE, the eNodeB can receive remote UE information (e.g., remote UE ID) via the relay UE in a newly defined message or an existing message, thereby releasing the direct connection of the remote UE. (8) The eNodeB can send a message to the remote UE to initiate its relay discovery process based on the measurement report of the remote UE. (9) The eNodeB can send configuration information related to the threshold of link quality measurement in a discovery configuration container or a new container to the remote UE in a dedicated signaling message. (10) The eNodeB can send configuration information to control the initiation of the relay discovery process of the remote UE. (11) When the remote UE context is obtained from the core network, the eNodeB can store the remote UE context for the purpose of relay reselection.

[0119] Another example provides a function 1900 of a relay user equipment (UE) that is operable to act as a relay between a remote UE and an eNodeB, as shown in the flowchart of Figure 19 The function can be implemented as a method, or the function can be executed as instructions on a machine, where the instructions are included on at least one computer-readable medium or at least one non-transitory machine-readable storage medium. The relay UE can include one or more processors and a memory, which are configured to: receive a relay configuration message including one or more relay configuration parameters from the eNodeB, as shown in block 1910. The relay UE can include one or more processors and a memory, which are configured to: identify relay UE information associated with one or more relay parameters of the relay UE, as shown in block 1920. The relay UE can include one or more processors and a memory, which are configured to: determine to act as a relay for the remote UE based on the one or more relay configuration parameters and the relay UE information at the relay UE, as shown in block 1930. The relay UE can include one or more processors and a memory, which are configured to: transmit a discovery message from the relay UE to the remote UE to establish a direct connection between the relay UE and the remote UE, where the relay UE is configured to relay data from the eNodeB to the remote UE via the direct connection between the relay UE and the remote UE, as shown in block 1940.

[0120] Another example provides a function 2000 of a relay user equipment (UE) that is operable to act as a relay between a remote UE and an eNodeB, as shown in Figure 20as shown in the flowchart therein. This functionality can be implemented as a method or can be executed as instructions on a machine, where the instructions are included on at least one computer-readable medium or at least one non-transitory machine-readable storage medium. The relay UE can include one or more processors and a memory, which are configured to: receive, from an eNodeB, a relay configuration message including one or more relay configuration parameters, as shown in block 2010. The relay UE can include one or more processors and a memory, which are configured to: determine, at the relay UE, based on the one or more relay configuration parameters and relay UE information, that the relay UE functions as a relay for a remote UE, as shown in block 2020. The relay UE can include one or more processors and a memory, which are configured to: send, from the relay UE to the eNodeB, a sidelink information message indicating that the relay UE functions as a relay for a remote UE, as shown in block 2030. The relay UE can include one or more processors and a memory, which are configured to: receive, from the eNodeB, a relay initiation and configuration message authorizing the relay UE to function as a relay for a remote UE, as shown in block 2040.

[0121] Another example provides at least one machine-readable storage medium having instructions 2100 included thereon for instructing a relay user equipment (UE) to function as a relay between an eNodeB and a remote UE, as Figure 21 shown in the flowchart therein. The method can be executed as instructions on a machine, where the instructions are included on at least one computer-readable medium or at least one non-transitory machine-readable storage medium. When executed, the instructions perform the following operations: transmit, using at least one processor of the eNodeB, a relay configuration message including one or more relay configuration parameters to the relay UE, as shown in block 2110. When executed, the instructions perform the following operations: receive, using at least one processor of the eNodeB, from the relay UE, a sidelink information message indicating that the relay UE functions as a relay for a remote UE, where the relay UE is configured to determine that the relay UE functions as a relay based on the one or more relay configuration parameters and relay UE information, as shown in block 2120. When executed, the instructions perform the following operations: transmit, using at least one processor of the eNodeB, a relay initiation and configuration message to the relay UE, the relay initiation and configuration message authorizing the relay UE to function as a relay for a remote UE, where the relay UE is configured to establish a direct connection between the relay UE and the remote UE based on the relay initiation and configuration message received from the eNodeB, as shown in block 2130.

[0122] Another example provides functionality 2200 of a remote user equipment (UE) operable to communicate with an eNodeB via a relay UE, as Figure 22As shown in the flowchart in []. This function can be implemented as a method, or this function can be executed as instructions on a machine, where the instructions are included on at least one computer-readable medium or at least one non-transitory machine-readable storage medium. The remote UE may include one or more processors and a memory, which are configured to: establish a direct connection with the relay UE at the remote UE through a discovery process, where the remote UE is configured to establish a direct connection with the relay UE using one or more relay configuration parameters received from the eNodeB in broadcast or dedicated signaling, as shown in block 2210. The remote UE may include one or more processors and a memory, which are configured to: transmit a sidelink information message indicating that the remote UE has established a direct connection with the relay UE to the eNodeB, and request the eNodeB to release the radio resource control (RRC) connection with the remote UE, where the eNodeB is configured to release the RRC connection with the remote UE, as shown in block 2220.

[0123] Figure 23 An example illustration of a user equipment (UE) device 2300 is provided. The UE device 2300 is, for example, a wireless device, a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet computer, a mobile phone, or other types of wireless devices. The UE device 2300 may include one or more antennas, which are configured to communicate with the following nodes or transmission stations: for example, a base station (BS), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), a remote radio unit (RRU), a central processing module (CPM), or other types of wireless wide area network (WWAN) access points. The UE device 2300 may be configured to communicate using at least one wireless communication standard including 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The UE device 2300 may use a separate antenna for each wireless communication standard, or use a shared antenna for multiple wireless communication standards for communication. The UE device 2300 may communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and / or a WWAN.

[0124] In some embodiments, the UE device 2300 may include an application circuit 2302, a baseband circuit 2304, a radio frequency (RF) circuit 2306, a front-end module (FEM) circuit 2308, and one or more antennas 2310, which are coupled together at least as shown.

[0125] The application circuitry 2302 may include one or more application processors. For example, the application circuitry 2302 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The (one or more) processors may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processor may be coupled to the memory / storage and / or may include the memory / storage, and may be configured to execute instructions stored in the memory / storage such that various applications and / or operating systems can run on the system.

[0126] The baseband circuitry 2304 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 2304 may include one or more baseband processors and / or control logic to process baseband signals received from the receive signal path of the RF circuitry 2306 and to generate baseband signals for the transmit signal path of the RF circuitry 2306. The baseband processing circuitry 2304 may be connected to the application circuitry 2302 via an interface for generating and processing baseband signals and for controlling the operation of the RF circuitry 2306. For example, in some embodiments, the baseband circuitry 2304 may include a second-generation (2G) baseband processor 2304a, a third-generation (3G) baseband processor 2304b, a fourth-generation (4G) baseband processor 2304c, and / or other baseband processors 2304d for other existing generations, generations under development, or future generations to be developed (e.g., fifth-generation (5G), 6G, etc.). The baseband circuitry 2304 (e.g., one or more of the baseband processors 2304a-d) may process various radio control functions that enable communication with one or more radio networks via the RF circuitry 2306. The radio control functions may include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some embodiments, the modulation / demodulation circuitry of the baseband circuitry 2304 may include fast Fourier transform (FFT), precoding, and / or constellation mapping / demapping functions. In some embodiments, the encoding / decoding circuitry of the baseband circuitry 2304 may include convolutional, tail-biting convolutional, turbo, Viterbi, and / or low density parity check (LDPC) encoder / decoder functions. The embodiments of the modulation / demodulation and encoder / decoder functions are not limited to these examples and may include other suitable functions in other embodiments.

[0127] In some embodiments, the baseband circuit 2304 may include elements of a protocol stack, such as elements of an Evolved Universal Terrestrial Radio Access Network (EUTRAN) protocol, including, for example, Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and / or Radio Resource Control (RRC) elements. The central processing unit (CPU) 2304e of the baseband circuit 2304 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP, and / or RRC layers. In some embodiments, the baseband circuit may include one or more audio digital signal processors (DSPs) 2304f. The (one or more) audio DSPs 2304f may include elements for compression / decompression and echo cancellation, and in other embodiments may include other suitable processing elements. In some embodiments, the components of the baseband circuit may be appropriately combined in a single chip, a single chipset, or disposed on the same circuit board. In some embodiments, some or all of the components of the baseband circuit 2304 and the application circuit 2302 may be implemented together, such as implemented on a system-on-chip (SOC).

[0128] In some embodiments, the baseband circuit 2304 may provide communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuit 2304 may support communication with an Evolved Universal Terrestrial Radio Access Network (EUTRAN) and / or other Wireless Metropolitan Area Networks (WMANs), Wireless Local Area Networks (WLANs), Wireless Personal Area Networks (WPANs). Embodiments in which the baseband circuit 2304 is configured to support radio communication of more than one wireless protocol may be referred to as multi-mode baseband circuits.

[0129] The RF circuit 2306 may communicate with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuit 2306 may include switches, filters, amplifiers, etc. to assist in communication with the wireless network. The RF circuit 2306 may include a receive signal path that may include circuitry for down-converting an RF signal received from the FEM circuit 2308 and providing a baseband signal to the baseband circuit 2304. The RF circuit 2306 may also include a transmit signal path that may include circuitry for up-converting a baseband signal provided by the baseband circuit 2304 and providing an RF output signal to the FEM circuit 2308 for transmission.

[0130] In some embodiments, the RF circuit 2306 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuit 2306 may include a mixer circuit 2306a, an amplifier circuit 2306b, and a filter circuit 2306c. The transmit signal path of the RF circuit 2306 may include a filter circuit 2306c and a mixer circuit 2306a. The RF circuit 2306 may further include a synthesizer circuit 2306d for synthesizing the frequencies used by the mixer circuits 2306a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuit 2306a of the receive signal path may be configured to down-convert an RF signal received from the FEM circuit 2308 based on the synthesized frequency provided by the synthesizer circuit 2306d. The amplifier circuit 2306b may be configured to amplify the down-converted signal, and the filter circuit 2306c may be a low-pass filter (LPF) or a band-pass filter (BPF) configured to remove unwanted signals from the down-converted signal to generate an output baseband signal. The output baseband signal may be provided to the baseband circuit 2304 for further processing. In some embodiments, the output baseband signal may be a zero-frequency baseband signal, but this is not required. In some embodiments, the mixer circuit 2306a of the receive signal path may include a passive mixer, but the scope of the embodiments is not limited in this regard.

[0131] In some embodiments, the mixer circuit 2306a of the transmit signal path may be configured to up-convert an input baseband signal based on the synthesized frequency provided by the synthesizer circuit 2306d to generate an RF output signal for the FEM circuit 2308. The baseband signal may be provided by the baseband circuit 2304 and may be filtered by the filter circuit 2306c. The filter circuit 2306c may include a low-pass filter (LPF), but the scope of the embodiments is not limited in this regard.

[0132] In some embodiments, the mixer circuit 2306a of the receive signal path and the mixer circuit 2306a of the transmit signal path may include two or more mixers and may be arranged respectively for quadrature down-conversion and / or up-conversion. In some embodiments, the mixer circuit 2306a of the receive signal path and the mixer circuit 2306a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuit 2306a of the receive signal path and the mixer circuit 2306a of the transmit signal path may be arranged respectively for direct down-conversion and / or direct up-conversion. In some embodiments, the mixer circuit 2306a of the receive signal path and the mixer circuit 2306a of the transmit signal path may be configured for superheterodyne operation.

[0133] In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, but the scope of the embodiments is not limited in this regard. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, the RF circuit 2306 may include an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) circuit, and the baseband circuit 2304 may include a digital baseband interface for communicating with the RF circuit 2306.

[0134] In some dual-mode embodiments, separate radio IC circuits may be provided for processing signals of each spectrum, but the scope of the embodiments is not limited in this regard.

[0135] In some embodiments, the synthesizer circuit 2306d may be a fractional-N synthesizer or a fractional N / N+1 synthesizer, but the scope of the embodiments is not limited in this regard, as other types of frequency synthesizers may be suitable. For example, the synthesizer circuit 2306d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase-locked loop with a frequency divider.

[0136] The synthesizer circuit 2306d may be configured to synthesize an output frequency for use by the mixer circuit 2306a of the RF circuit 2306 based on a frequency input and a frequency divider control input. In some embodiments, the synthesizer circuit 2306d may be a fractional N / N+1 synthesizer.

[0137] In some embodiments, the frequency input may be provided by a voltage-controlled oscillator (VCO), but this is not required. Depending on the desired output frequency, the frequency divider control input may be provided by the baseband circuit 2304 or the application processor 2302. In some embodiments, the frequency divider control input (e.g., N) may be determined according to a look-up table based on the channel indicated by the application processor 2302.

[0138] The synthesizer circuit 2306d of the RF circuit 2306 may include a frequency divider, a delay-locked loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the frequency divider may be a dual-mode frequency divider (DMD), and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide an input signal by N or N+1 (e.g., based on a carry output) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded tunable delay elements, a phase detector, a charge pump, and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period into Nd equal phase bins, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO period.

[0139] In some embodiments, the synthesizer circuit 2306d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency), and is used in combination with an orthogonal generator and a frequency divider circuit to generate multiple signals having multiple different phases relative to each other at the carrier frequency. In some embodiments, the output frequency may be the LO frequency (f LO ). In some embodiments, the RF circuit 2306 may include an IQ / polarity converter.

[0140] The FEM circuit 2308 may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas 2310, amplify the received signals, and provide an amplified version of the received signals to the RF circuit 2306 for further processing. The FEM circuit 2308 may also include a transmit signal path that may include circuitry configured to amplify signals provided by the RF circuit 2306 for transmission for transmission by one or more of the one or more antennas 2310.

[0141] In some embodiments, the FEM circuit 2308 may include a TX / RX converter to switch between operating in a transmit mode and a receive mode. The FEM circuit may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuit may include a low noise amplifier (LNA) to amplify a received RF signal and provide the amplified received RF signal as an output (e.g., to the RF circuit 2306). The transmit signal path of the FEM circuit 2308 may include a power amplifier (PA) for amplifying an input RF signal (e.g., provided by the RF circuit 2306), and one or more filters for generating an RF signal for subsequent transmission (e.g., via one or more of the one or more antennas 2310).

[0142] Figure 24 An example illustration of a wireless device such as a user equipment (UE), mobile station (MS), mobile wireless device, mobile communication device, tablet computer, cellular phone, or other type of wireless device is provided. The wireless device may include one or more antennas configured to communicate with a node, macro node, low power node (LPN), or transmission station (e.g., base station (BS), evolved node B (eNB), baseband processing unit (BBU), remote radio head (RRH), remote radio equipment (RRE), relay station (RS), radio equipment (RE), or other type of wireless wide area network (WWAN) access point). The wireless device may be configured to communicate using at least one wireless communication standard, such as but not limited to 3GPP LTE, WiMAX, high speed packet access (HSPA), Bluetooth, and WiFi. The wireless device may use a separate antenna for each wireless communication standard, or communicate using a shared antenna for multiple wireless communication standards. The wireless device may communicate in a wireless local area network (WLAN), wireless personal area network (WPAN), and / or WWAN. The wireless device may also include a wireless modem. The wireless modem may include, for example, a wireless radio transceiver and baseband circuitry (e.g., a baseband processor). In one example, the wireless modem may modulate signals transmitted by the wireless device via one or more antennas and demodulate signals received by the wireless device via one or more antennas.

[0143] Figure 24Also provided is an illustration of a microphone and one or more speakers that can be used for audio input and output from a wireless device. The display screen can be a liquid crystal display (LCD) screen or other types of display screens, such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen can use capacitive, resistive, or other types of touch screen technologies. The application processor and the graphics processor can be coupled to an internal memory to provide processing and display capabilities. The non-volatile memory port can also be used to provide data input / output options to the user. The non-volatile memory port can also be used to expand the memory capabilities of the wireless device. The keyboard can be integrated with the wireless device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.

[0144] Example

[0145] The following examples relate to specific technical embodiments and point out specific features, elements, or actions that can be used or otherwise combined in implementing these embodiments.

[0146] Example 1 includes an apparatus for a relay user equipment (UE) that is operable to act as a relay between a remote UE and an eNodeB. The apparatus includes one or more processors and a memory, and the one or more processors and the memory are configured to: receive a relay configuration message including one or more relay configuration parameters from the eNodeB; identify relay UE information associated with one or more relay parameters of the relay UE; determine, at the relay UE, to act as a relay for the remote UE based on the one or more relay configuration parameters and the relay UE information; and transmit a discovery message from the relay UE to the remote UE to establish a direct connection between the relay UE and the remote UE, wherein the relay UE is configured to relay data from the eNodeB to the remote UE through the direct connection between the relay UE and the remote UE.

[0147] Example 2 includes the apparatus of Example 1, further configured to transmit a sidelink information message to the eNodeB to indicate that the relay UE is acting as a relay for the remote UE.

[0148] Example 3 includes the apparatus of any one of Examples 1-2, wherein the relay UE is within the coverage area of the eNodeB and the remote UE is outside the coverage area of the eNodeB.

[0149] Example 4 includes the apparatus of any one of Examples 1-3, wherein the relay UE is configured to receive the relay configuration message in a defined system information block (SIB) through a broadcast from the eNodeB.

[0150] Example 5 includes the apparatus of any one of Examples 1-4, wherein the relay configuration parameters include one or more of the following: a first quality threshold parameter, which represents the minimum link quality for the relay UE to act as a relay; a second quality threshold parameter, which represents the maximum link quality at which the relay UE cannot act as a relay; a relay mobility configuration parameter, which indicates the acceptable mobility state of the relay UE; an idle parameter, which indicates whether the relay UE is allowed to perform discovery and initiate relay operation from the idle mode; and a relay operation support parameter, which represents whether the cell associated with the eNodeB allows relay operation.

[0151] Example 6 includes the apparatus of any one of Examples 1-5, wherein the relay UE information includes one or more of the following: serving cell measurement, battery status information, and user settings.

[0152] Example 7 includes the apparatus of any one of Examples 1-6, wherein the relay UE is configured to determine to act as a relay based on a comparison between the serving cell measurement included in the relay UE information and the quality threshold parameter included in one or more configuration parameters.

[0153] Example 8 includes the apparatus of any one of Examples 1-7, wherein the relay UE includes at least one of an antenna, a touch-sensitive display screen, a speaker, a microphone, a graphics processor, an application processor, a baseband processor, an internal memory, a non-volatile memory port, and combinations thereof.

[0154] Example 9 includes an apparatus for a relay user equipment (UE) that is operable to act as a relay between a remote UE and an eNodeB, the apparatus including one or more processors and a memory, the one or more processors and the memory being configured to: receive, from the eNodeB, a relay configuration message including one or more relay configuration parameters; determine, at the relay UE, based on the one or more relay configuration parameters and the relay UE information, that the relay UE functionally acts as a relay for the remote UE; transmit, from the relay UE to the eNodeB, a sidelink information message to indicate that the relay UE functionally acts as a relay for the remote UE; and receive, in broadcast or dedicated signaling, from the eNodeB, a set of relay initiation and configuration parameters authorizing the relay UE to act as a relay for the remote UE.

[0155] Example 10 includes the apparatus of Example 9, further configured to transmit, from the relay UE to the remote UE, a discovery message to establish a direct connection between the relay UE and the remote UE, wherein the relay UE is configured to relay data from the eNodeB to the remote UE through the direct connection between the relay UE and the remote UE.

[0156] Example 11 includes the apparatus of any one of Examples 9 - 10, wherein the relay UE is configured to: receive a relay configuration message in a defined system information block (SIB) via broadcast from an eNodeB; and receive a relay initiation and configuration message via dedicated signaling from the eNodeB.

[0157] Example 12 includes the apparatus of any one of Examples 9 - 11, wherein the relay initiation and configuration message includes one or more relay configuration parameters specific to the relay UE.

[0158] Example 13 includes the apparatus of any one of Examples 9 - 12, wherein the relay UE is within the coverage area of the eNodeB, and the remote UE is outside the coverage area of the eNodeB.

[0159] Example 14 includes the apparatus of any one of Examples 9 - 13, wherein the relay UE information includes one or more of the following items: serving cell measurement, battery status information, and user settings.

[0160] Example 15 includes the apparatus of any one of Examples 9 - 14, wherein the relay UE is configured to determine that the relay UE functions as a relay based on a comparison between the serving cell measurement included in the relay UE information and a quality threshold parameter included in one or more configuration parameters sent in the broadcast signaling from the eNB.

[0161] Example 16 includes at least one machine - readable storage medium having instructions stored thereon for instructing a relay user equipment (UE) to function as a relay between an eNodeB and a remote UE, the instructions when executed perform the following operations: use at least one processor of the eNodeB to transmit a relay configuration message including one or more relay configuration parameters to the relay UE; use at least one processor of the eNodeB to receive from the relay UE a sidelink information message indicating that the relay UE functions as a relay for the remote UE, wherein the relay UE is configured to determine that the relay UE functions as a relay based on one or more relay configuration parameters and relay UE information; and use at least one processor of the eNodeB to transmit a relay initiation and configuration message to the relay UE, the relay initiation and configuration message authorizing the relay UE to function as a relay for the remote UE, wherein the relay UE is configured to establish a direct connection between the relay UE and the remote UE based on the relay initiation and configuration message received from the eNodeB.

[0162] Example 17 includes the at least one machine - readable storage medium of Example 16, further including instructions that when executed by at least one processor of the eNodeB perform the following operation: transmit data to the remote UE via the relay UE, wherein the relay UE is configured to receive data from the eNodeB and relay the data to the remote UE via a direct connection between the relay UE and the remote UE.

[0163] Example 18 includes at least one machine-readable storage medium of any one of Examples 16 - 17, wherein the relay UE is within the coverage area of the eNodeB, and the remote UE is outside the coverage area of the eNodeB or within the coverage area of the eNodeB.

[0164] Example 19 includes at least one machine-readable storage medium of any one of Examples 16 - 18, wherein the eNodeB transmits relay configuration parameters to the relay UE via a broadcast message, and the eNodeB transmits a relay initiation and configuration message to the relay UE via dedicated signaling.

[0165] Example 20 includes at least one machine-readable storage medium of any one of Examples 16 - 19, and further includes instructions that, when executed by at least one processor of the eNodeB, perform the following operations: when the remote UE is within the coverage area of the eNodeB, transmit a relay initiation and configuration message to the relay UE to authorize the relay UE to act as a relay after receiving a measurement report from the remote UE, wherein the measurement report indicates that the connection between the remote UE and the eNodeB is below a defined threshold.

[0166] Example 21 includes at least one machine-readable storage medium of any one of Examples 16 - 20, and further includes instructions that, when executed by at least one processor of the eNodeB, perform the following operations: receive a message from the relay UE, the message indicating that a direct connection between the relay UE and the remote UE has been successfully established, wherein the remote UE is within the coverage of the eNodeB; and release the radio resource control (RRC) connection with the remote UE.

[0167] Example 22 includes an apparatus for a remote user equipment (UE) that is operable to communicate with an eNodeB via a relay UE, the apparatus including one or more processors and a memory, the one or more processors and the memory being configured to: establish a direct connection with the relay UE at the remote UE via a discovery process, wherein the remote UE is configured to establish the direct connection with the relay UE using one or more relay configuration parameters received from the eNodeB in a broadcast or dedicated signaling; and transmit a sidelink information message indicating that the remote UE has established a direct connection with the relay UE to the eNodeB, and request the eNodeB to release the radio resource control (RRC) connection with the remote UE, wherein the eNodeB is configured to release the RRC connection with the remote UE.

[0168] Example 23 includes the apparatus of Example 22 and is further configured to perform data communication with an eNodeB through a relay UE, where the relay UE is configured to receive data from the eNodeB or a remote UE and relay the data to the remote UE or the eNodeB respectively through a direct connection between the relay UE and the remote UE.

[0169] Example 24 includes the apparatus of any one of Examples 22-23 and is further configured to discard the direct connection with the relay UE after the relay UE comes within the coverage of a second eNodeB and establishes a connection with the second eNodeB.

[0170] Example 25 includes the apparatus of any one of Examples 22-24 and is further configured to establish a direct connection with the relay UE based on an instruction from the eNodeB, where the eNodeB sends the instruction after receiving a measurement report from the remote UE, and the measurement report indicates that the quality of the RRC connection between the remote UE and the eNodeB is lower than a defined threshold.

[0171] Example 26 includes the apparatus of any one of Examples 22-25 and is further configured to trigger a discovery process for establishing a direct connection with the relay UE when the quality of the Uu connection between the remote UE and the eNodeB is lower than a defined threshold.

[0172] Various techniques or certain aspects or portions thereof may take the form of program code (i.e., instructions) embodied in a tangible medium such as a floppy disk, a compact disc read-only memory (CD-ROM), a hard disk drive, a non-transitory computer-readable storage medium, or any other machine-readable storage medium, wherein when the program code is loaded into and executed by a machine such as a computer, the machine becomes an apparatus for practicing the various techniques. The non-transitory computer-readable storage medium may be a computer-readable storage medium that does not include a signal. In the case where the program code is executed on a programmable computer, the computing device may include a processor, a processor-readable storage medium (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and / or storage elements may be random access memory (RAM), erasable programmable read-only memory (EPROM), flash drive, optical drive, magnetic hard disk drive, solid state drive, or other media for storing electronic data. Nodes and wireless devices may also include a transceiver module (i.e., transceiver), a counter module (i.e., counter), a processing module (i.e., processor), and / or a clock module (i.e., clock) or timer module (i.e., timer). One or more programs that implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, etc. Such programs may be implemented in a high-level programming or object-oriented programming language to communicate with a computer system. However, if desired, the (one or more) programs may be implemented in assembly or machine language. In any case, the language may be a compiled or interpreted language and combined with a hardware implementation.

[0173] As used herein, the term “circuitry” may refer to, be part of, or include: an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and / or memory (shared, dedicated, or group) that executes one or more software or firmware programs, combinational logic circuitry, and / or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in one or more software or firmware modules, or the functions associated with the circuitry may be implemented by one or more software or firmware modules. In some embodiments, the circuitry may include logic that is at least partially operable in hardware.

[0174] It should be understood that many of the functional units described in this specification have been labeled as modules to more particularly emphasize the independence of their implementation. For example, a module can be implemented as a hardware circuit including custom large-scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module can also be implemented in programmable hardware devices such as field-programmable gate arrays, programmable array logic, programmable logic devices, etc.

[0175] A module can also be implemented in software for execution by various types of processors. The identified modules of executable code can include, for example, one or more physical or logical blocks of computer instructions, which can be organized, for example, as objects, procedures, or functions. However, the executable files of the identified modules may not be physically located in one place, but may include different instructions stored in different locations, which, when logically combined together, constitute the module and achieve the declared purpose of the module.

[0176] In fact, the modules of executable code can be a single instruction or multiple instructions, and can even be distributed over several different code segments among different programs and across several storage devices. Similarly, the operational data can be identified and shown within a module herein, and can be implemented in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including different storage devices, and exist at least partially only as electronic signals on a system or network. A module can be passive or active, including an agent operable to perform the required function.

[0177] In this specification, references to "an example" or "exemplary" mean that the particular features, structures, or characteristics described in connection with the example are included in at least one embodiment of the present technology. Thus, the appearances of the phrase "in an example" or the word "exemplary" in various places in this specification are not necessarily all referring to the same embodiment.

[0178] As used herein, for convenience purposes, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list. However, these lists should be construed such that each member of the list is individually identified as a separate and unique member. Thus, without contrary indication, any individual member of such a list should not be considered an actual equivalent of any other member of the same list solely based on its appearance in a common group. In addition, various embodiments and examples of the present technology may be mentioned along with alternatives to its various components. It should be understood that such embodiments, examples, and alternatives should not be construed as actual equivalents of each other, but will be considered separate and autonomous representations of the present technology.

[0179] In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of the technical embodiments. However, those skilled in the relevant art will recognize that the technology may be practiced without one or more of the specific details or in combination with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the technology.

[0180] While the foregoing examples illustrate the principles of the technology in one or more particular applications, it will be apparent to those of ordinary skill in the art that various modifications can be made in the form, use, and details of the implementation without departing from the principles and concepts of the technology and without the need for creative effort. Accordingly, the technology is not intended to be limited except as by the appended claims.

Claims

1. An apparatus for a relay user equipment (UE), the relay UE being operable to act as a relay between a remote UE and a base station, the apparatus comprising: a memory; and one or more processors configured to: receive, from the base station, a relay configuration message including one or more relay configuration parameters; identify relay UE information associated with one or more relay parameters of the relay UE; determine, at the relay UE, to act as a relay for the remote UE based on the one or more relay configuration parameters and the relay UE information, wherein the relay configuration parameters include: a relay mobility configuration parameter indicating an acceptable mobility state for the relay UE to act as a relay; a first quality threshold parameter representing a minimum link quality for the relay UE to act as a relay; and a second quality threshold parameter representing a maximum link quality beyond which the relay UE cannot act as a relay; and transmit, from the relay UE to the remote UE, a discovery message to establish a direct connection between the relay UE and the remote UE, wherein the relay UE is configured to relay data from the base station to the remote UE via the direct connection between the relay UE and the remote UE.

2. The apparatus according to claim 1, further configured to transmit a sidelink information message to the base station to indicate that the relay UE is acting as a relay for the remote UE.

3. The device according to claim 1, wherein, The relay UE is within the coverage area of the base station, and the remote UE is outside the coverage area of the base station.

4. The device according to claim 1, wherein, The relay UE is configured to receive the relay configuration message via broadcast from the base station in a defined system information block (SIB).

5. The device according to claim 1, wherein, The relay configuration parameters further include: an idle parameter indicating whether the relay UE is allowed to perform discovery and initiate a relay operation from an idle mode; and a relay operation support parameter representing whether a cell associated with the base station allows relay operation.

6. The device according to claim 1, wherein, The relay UE information includes one or more of the following: serving cell measurement, battery status information, and user settings.

7. The device according to claim 1, wherein The relay UE is configured to determine to act as a relay based on a comparison between the serving cell measurement included in the relay UE information and the quality threshold parameters included in the one or more configuration parameters.

8. The device according to claim 1, wherein The relay UE includes at least one of the following: an antenna, a touch-sensitive display screen, a speaker, a microphone, a graphics processor, an application processor, a baseband processor, an internal memory, a non-volatile memory port, and combinations thereof.

9. A method for a relay user equipment (UE), the relay UE being operable to act as a relay between a remote UE and a base station, the method comprising: receiving, from the base station, a relay configuration message including one or more relay configuration parameters; identifying relay UE information associated with one or more relay parameters of the relay UE; At the relay UE, determine to act as a relay for the remote UE based on the one or more relay configuration parameters and the relay UE information, where the relay configuration parameters include: a relay mobility configuration parameter indicating an acceptable mobility state for the relay UE to act as a relay; a first quality threshold parameter representing a minimum link quality for the relay UE to act as a relay; and a second quality threshold parameter representing a maximum link quality, beyond which the relay UE cannot act as a relay; and Transmit a discovery message from the relay UE to the remote UE to establish a direct connection between the relay UE and the remote UE, where the relay UE is configured to relay data from the base station to the remote UE through the direct connection between the relay UE and the remote UE.

10. The method according to claim 9, further comprising transmitting a sidelink information message to the base station to indicate that the relay UE is acting as a relay for the remote UE.

11. The method according to claim 9, wherein, The relay UE is within the coverage area of the base station, and the remote UE is outside the coverage area of the base station.

12. The method according to claim 9, wherein, The relay configuration parameters further include: An idle parameter indicating whether the relay UE is allowed to perform discovery and initiate a relay operation from the idle mode; and A relay operation support parameter representing whether the cell associated with the base station allows relay operations.

13. The method according to claim 9, wherein, The relay UE information includes one or more of the following items: serving cell measurement, battery status information, and user settings.

14. The method according to claim 9, wherein, The relay UE is configured to determine to act as a relay based on a comparison between the serving cell measurement included in the relay UE information and the quality threshold parameters included in the one or more configuration parameters.

15. A non-transitory computer-readable storage medium storing instructions thereon for instructing a relay user equipment UE to act as a relay between a remote UE and a base station, the instructions when executed by one or more processors of the relay UE cause the relay UE to: Receive a relay configuration message including one or more relay configuration parameters from the base station; Identify relay UE information associated with one or more relay parameters of the relay UE; Determine, at the relay UE, to act as a relay for the remote UE based on the one or more relay configuration parameters and the relay UE information, wherein, The relay configuration parameters include: a relay mobility configuration parameter indicating an acceptable mobility state for the relay UE to act as a relay; a first quality threshold parameter representing a minimum link quality for the relay UE to act as a relay; and a second quality threshold parameter representing a maximum link quality, beyond which the relay UE cannot act as a relay; and Transmit a discovery message from the relay UE to the remote UE to establish a direct connection between the relay UE and the remote UE, where the relay UE is configured to relay data from the base station to the remote UE through the direct connection between the relay UE and the remote UE.

16. The non-transitory computer-readable storage medium according to claim 15, wherein, The instructions when executed by the one or more processors further cause the UE to: transmit a sidelink information message to the base station to indicate that the relay UE is acting as a relay for the remote UE.

17. The non-transitory computer-readable storage medium according to claim 15, wherein, The relay UE is within the coverage area of the base station, and the remote UE is outside the coverage area of the base station.

18. The non-transitory computer-readable storage medium according to claim 15, wherein, When executed by the one or more processors, the instruction configures the relay UE to receive the relay configuration message in a defined system information block (SIB) via a broadcast from the base station.

19. The non-transitory computer-readable storage medium according to claim 15, wherein, The relay UE information includes one or more of the following: serving cell measurements, battery status information, and user settings.

20. The non-transitory computer-readable storage medium according to claim 15, wherein, When executed by the one or more processors, the instruction configures the relay UE to determine to act as a relay based on a comparison between serving cell measurements included in the relay UE information and a quality threshold parameter included in the one or more configuration parameters.

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