System and method for device-to-device communication

Abstract

In some arrangements, a first BS (source BS) sends a handover request including a target cell ID to a second BS (target BS). The remote UE communicates with the first BS via a first indirect path including the first SL between the remote UE and the first relay UE or a first direct path between the remote UE and the first BS. The target cell ID includes an ID (e.g., a serving cell ID or an NCGI) of a serving cell of the second relay UE or a serving cell of the direct path. The first BS receives a handover response from the second BS.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communications, and more particularly, to abnormal conditions in device-to-device communications. Background Art

[0002] Sidelink (SL) communication refers to wireless radio communication between two or more User Equipment (UE). In this type of communication, two or more UEs that are geographically close to each other can communicate without being routed to a base station (BS) or a core network. Therefore, data transmission in SL communication is different from typical cellular network communication, which includes sending data to and receiving data from the BS. In SL communication, data is sent directly from a source UE to a target UE through, for example, a unified air interface (e.g., a PC5 interface) without passing through a BS. Summary of the invention

[0003] The example arrangements disclosed herein are intended to solve problems associated with one or more of the problems presented in the prior art, as well as to provide additional features, which will become apparent by reference to the following detailed description when combined with the accompanying drawings. According to various arrangements, example systems, methods, devices, and computer program products are disclosed herein. However, it should be understood that these arrangements are presented by way of example, not limitation, and it will be apparent to a person of ordinary skill in the art who reads this disclosure that various modifications can be made to the disclosed arrangements while remaining within the scope of this disclosure.

[0004] In some arrangements, a first BS (e.g., a serving BS) receives measurements from a remote UE. The remote UE communicates with the first BS via an indirect path including a first SL between the remote UE and a first relay UE or a direct path between the remote UE and the first BS. A communication method is selected based on the measurements. The communication method includes one of the following: 1) the remote UE communicates with a second BS (e.g., a target BS) using a direct path between the remote UE and the second BS; 2) the remote UE communicates with the second BS using an indirect path between the remote UE and the second BS, the indirect path including a second SL between the remote UE and the second relay UE; or 3) the remote UE communicates with the second BS using both a direct path and an indirect path.

[0005] In some arrangements, a first BS (source BS) sends a handover request including a target cell ID to a second BS (target BS). The remote UE communicates with the first BS via a first indirect path including a first SL between the remote UE and the first relay UE or a first direct path between the remote UE and the first BS. The target cell ID includes a serving cell (e.g., serving cell ID or NCGI) of the second relay UE or an ID of a serving cell of the direct path. The first BS receives a handover response from the second BS.

[0006] In some arrangements, a first UE (e.g., a remote UE) receives an ID of a second UE (e.g., a relay UE) and a channel configuration of a SL communication channel between the first UE and the second UE from a BS via a direct path. The first UE establishes a SL communication channel with the second UE using the ID of the second UE and the channel configuration.

[0007] The above-described aspects and other aspects and embodiments thereof are described in more detail in the drawings, the description and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various example arrangements of the present solution are described in detail below with reference to the following figures or drawings. The drawings are provided for illustrative purposes only and depict only example arrangements of the present solution to facilitate the reader's understanding of the present solution. Therefore, the drawings should not be considered to limit the breadth, scope or applicability of the present solution. It should be noted that for clarity and ease of illustration, these drawings are not necessarily drawn to scale.

[0009] Figure 1A is a diagram illustrating an example wireless communication network according to various arrangements.

[0010] Figure 1B is a diagram illustrating a block diagram of an example wireless communication system for sending and receiving downlink, uplink and / or SL communication signals according to various arrangements.

[0011] Figure 2 Example scenarios of SL communications according to various arrangements are shown.

[0012] Figure 3 is a diagram illustrating a switching method according to various arrangements.

[0013] Figure 4 is a diagram illustrating a switching method according to various arrangements.

[0014] Figure 5 is a diagram illustrating a switching method according to various arrangements.

[0015] Figure 6 is a diagram illustrating an example method for adding an indirect path in addition to a direct path according to various arrangements.

[0016] Fig. 7A is a diagram illustrating example intra-cell multipath scenarios according to various arrangements.

[0017] Figure 7B is a diagram illustrating example inter-cell multipath scenarios according to various arrangements.

[0018] Figure 8 is a flow chart illustrating an example method for managing SL communications according to various arrangements.

[0019] Fig. 9 is a flow chart illustrating an example method for managing SL communications according to various arrangements.

[0020] Fig.10 is a flow chart illustrating an example method for managing SL communications according to various arrangements. DETAILED DESCRIPTION

[0021] Various example arrangements of the present solution are described below with reference to the accompanying drawings to enable those of ordinary skill in the art to make and use the present solution. As will be apparent to those of ordinary skill in the art, after reading this disclosure, various changes or modifications may be made to the examples described herein without departing from the scope of the present solution. Therefore, the present solution is not limited to the example arrangements and applications described and illustrated herein. In addition, the specific order or hierarchy of steps in the methods disclosed herein are merely example methods. Based on design preferences, the specific order or hierarchy of steps of the disclosed methods or processes may be rearranged while remaining within the scope of the present solution. Therefore, it will be understood by those of ordinary skill in the art that the methods and techniques disclosed herein present various steps or actions in a sample order, and unless otherwise expressly stated, the present solution is not limited to the specific order or hierarchy presented.

[0022] Such arrangements involve New Radio (NR) SL relay communications and in particular, SL UE to network relay path switching with single or multipath. For example, some arrangements involve negotiating a path switching configuration between a source gNB and a target gNB for a remote UE. Some arrangements involve triggering an RRC idle / inactive relay UE to enter an RRC connected state during indirect path addition for multipath communications. In some arrangements, emergency-only services for the remote UE are ensured.

[0023] With the emergence of wireless multimedia services, users' demand for high data rates and user experience continues to increase, which puts higher requirements on the system capacity and coverage of traditional cellular networks. In addition, public safety, social networks, close-range data sharing, and local advertising have gradually expanded the demand for proximity services, which allow users to understand and communicate with nearby users or objects. Traditional BS-centric cellular networks have limited high data rate capabilities and support for proximity services. In this context, device-to-device (D2D) communication emerges to address the shortcomings of the BS-centric model. The application of D2D technology can reduce the burden on cellular networks, reduce UE battery power consumption, increase data rates, and improve the robustness of network infrastructure, thereby meeting the above requirements of high data rate services and proximity services. D2D technology is also known as Proximity Service (ProSe), single-sided / sidelink / SL communication, etc.

[0024] Reference Figure 1A , an example wireless communication system 100 is shown. The wireless communication system 100 shows group communication within a cellular network. In the wireless communication system, the network-side communication nodes or BSs may include Next Generation NodeB (GNB), E-UTRAN NodeB (also known as Evolved NodeB, eNodeB or eNB), micro-micro stations, femto-micro stations, Transmission / Reception Points (TRP), Access Points (AP), etc. The terminal-side nodes or UEs may include devices such as, for example, mobile devices, smart phones, cellular phones, personal digital assistants (PDA), tablet computers, laptop computers, wearable devices, vehicles with vehicle communication systems, etc. In Figure 1A In the embodiment, the network side communication node and the terminal side communication node are represented by BS 102 and UE 104a and UE 104b respectively. In some arrangements, BS 102 and UE 104a / UE 104b are sometimes referred to as "wireless communication nodes" and "wireless communication devices" respectively. Such communication nodes / devices can perform wireless communication.

[0025] exist Figure 1A1 , BS 102 may define a cell 101 in which UE 104a and UE 104b are located. UE 104a and / or UE 104b may move or remain stationary within the coverage of cell 101. UE 104a may communicate with BS 102 via a communication channel 103a. Similarly, UE 104b may communicate with BS 102 via a communication channel 103b. In addition, UE 104a and UE 104b may communicate with each other via a communication channel 105. The communication channels 103a and 103b between the respective UEs and BSs may be implemented using an interface such as a Uu interface, which is also referred to as a Universal Mobile Telecommunication System (UMTS) air interface. The communication channel 105 between UEs is a SL communication channel and can be implemented using a PC5 interface, which is introduced to address high mobility and high density applications, such as, for example, D2D communication, vehicle-to-vehicle (V2V) communication, vehicle-to-pedestrian (V2P) communication, vehicle-to-infrastructure (V2I) communication, vehicle-to-network (V2N) communication, or the like. In some cases, the vehicle network communication mode can be collectively referred to as vehicle-to-everything (V2X) communication. BS 102 is connected to a core network (CN) 108 via an external interface 107 (e.g., an Iu interface).

[0026] To support a wider range of applications and services (e.g., in indoor relay communications, smart agriculture, smart factories, public safety, etc.), SL-based relay communications can be used to extend coverage and improve power consumption. Figure 1AIn the embodiment of the present invention, a remote UE (e.g., UE 104b) may be located in an area where BS coverage is weak or not covered. Therefore, the remote UE (e.g., UE 104b) does not communicate directly with BS102 or CN 108, but communicates indirectly with BS102 and CN108 via a relay UE (e.g., UE 104a) using SL communication channel 105, which can communicate directly with BS102 and CN 108 or indirectly communicate with BS102 and CN 108 via at least one other relay UE that can communicate directly with BS102 and CN 108. Therefore, the coverage of the network is extended and the capacity of the network is expanded. UE 104a is referred to as U2N relay, and UE 104b is referred to as remote UE. On the other hand, if remote UE 104b is within the coverage, remote UE 104b may be switched to a direct path (e.g., communication channel 103a). In addition, multipath relaying may be supported. For example, a remote UE 104b within coverage is connected to CN 108 via both a direct path (data is sent directly between the remote UE and the network via communication channel 103a) and an indirect path (data is forwarded via communication channels 103b and 105 via relay UE 104a), thereby improving reliability / robustness and throughput.

[0027] Figure 1B A block diagram of an example wireless communication system for sending and receiving downlink, uplink, and SL communication signals according to some arrangements of the present disclosure is shown. In some arrangements, the system may be configured as described above, such as Figure 1A The wireless communication system 100 can be used to send and receive data in a wireless communication environment.

[0028] like Figure 1A As described, the system generally includes a BS 102 and UEs 104a and 104b. BS 102 includes a BS transceiver module 110, a BS antenna 112, a BS memory module 116, a BS processor module 114, and a network communication module 118, each of which is coupled and interconnected to each other via a data communication bus 120 as needed. UE 104a includes a UE transceiver module 130a, a UE antenna 132a, a UE memory module 134a, and a UE processor module 136a, each of which is coupled and interconnected to each other via a data communication bus 140a as needed. Similarly, UE 104b includes a UE transceiver module 130b, a UE antenna 132b, a UE memory module 134b, and a UE processor module 136b, each of which is coupled and interconnected to each other via a data communication bus 140b as needed. BS 102 communicates with UE 104a and UE 104b via one or more of communication channels 150, which may be any wireless channel or other medium known in the art suitable for data transmission as described herein.

[0029] The system may also include Figure 1B Any number of modules outside the modules shown. It will be appreciated by those skilled in the art that the various illustrative blocks, modules, circuits, and processing logic described in conjunction with the arrangements disclosed herein can be implemented in hardware, computer-readable software, firmware, or any actual combination thereof. In order to clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are generally described according to their functions. Whether such functions are implemented as hardware, firmware, or software depends on specific applications and the design constraints imposed on the entire system. Personnel familiar with the concepts described herein can implement such functions in an appropriate manner for each specific application, but such implementation decisions should not be interpreted as limiting the scope of the present disclosure.

[0030] The wireless transmission from the antenna of one of UE 104a and UE 104b to the antenna of BS102 is referred to as uplink transmission, and the wireless transmission from the antenna of BS102 to the antenna of one of UE 104a and UE 104b is referred to as downlink transmission. According to some arrangements, each of UE transceiver modules 130a and 130b may be referred to as an uplink transceiver or UE transceiver in this article. The uplink transceiver may include a transmitter and a receiver circuit system, each of which is coupled to a corresponding antenna 132a and 132b. The duplex switch may alternatively couple the uplink transmitter or receiver to the uplink antenna in a time duplex mode. Similarly, the BS transceiver module 110 may be referred to as a downlink transceiver or BS transceiver in this article. The downlink transceiver may include an RF transmitter and a receiver circuit system each coupled to an antenna 112. The downlink duplex switch may alternatively couple the downlink transmitter or receiver to the antenna 112 in a time duplex mode. The operation of the transceivers 110 and 130a and 130b is coordinated in time so that the uplink receiver is coupled to the antennas 132a and 132b to receive transmissions via the wireless communication channel 150 while the downlink transmitter is coupled to the antenna 112. In some arrangements, the UE 104a and UE 104b can use the UE transceivers 130a and 130b through the respective antennas 132a and 132b to communicate with the BS 102 via the wireless communication channel 150. The wireless communication channel 150 can be any wireless channel or other medium known in the art suitable for downlink and / or uplink data transmission as described herein. The UE 104a and UE 104b can communicate with each other via the wireless communication channel 170. The wireless communication channel 170 can be any wireless channel or other medium suitable for SL data transmission as described herein.

[0031] Each of the UE transceivers 130a and 130b and the BS transceiver 110 is configured to communicate via a wireless data communication channel 150 and cooperate with an appropriately configured antenna arrangement that can support a specific wireless communication protocol and modulation scheme. In some arrangements, the UE transceivers 130a and 130b and the BS transceiver 110 are configured to support industry standards such as Long Term Evolution (LTE) and emerging 5G and 6G standards. However, it should be understood that the present disclosure is not necessarily limited to specific standards and related protocols in application. On the contrary, the UE transceivers 130a and 130b and the BS transceiver 110 can be configured to support alternative or additional wireless data communication protocols (including future standards or variations thereof).

[0032] The processor modules 136a and 136b and 114 can each be implemented or realized with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, which are designed to perform the functions described herein. In this manner, the processor can be implemented as a microprocessor, a controller, a microcontroller, a state machine, or the like. The processor can also be implemented as a combination of computing devices, such as a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

[0033] In addition, the methods and algorithms described in conjunction with the arrangements disclosed herein may be directly embodied in hardware, firmware, software modules executed by processor modules 114, 136a and 136b, respectively, or any practical combination thereof. Memory modules 116, 134a and 134b may be implemented as RAM memory, flash, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. In this regard, memory modules 116, 134a and 134b may be coupled to processor modules 114, 136a and 136b, respectively, so that processor modules 114, 136a and 136b may read information from memory modules 116, 134a and 134b, respectively, and write information to them. Memory modules 116, 134a and 134b may also be integrated into their respective processor modules 114, 136a and 136b. In some arrangements, the memory modules 116, 134a, and 134b may each include flash memory for storing temporary variables or other intermediate information during execution of instructions executed by the processor modules 116, 134a, and 134b, respectively. The memory modules 116, 134a, and 134b may also each include non-volatile memory for storing instructions executed by the processor modules 114, 136a, and 136b, respectively.

[0034] The network interface 118 generally represents the hardware, software, firmware, processing logic and / or other components of the BS 102, which implement bidirectional communication between the BS transceiver 110 and other network components and communication nodes configured to communicate with the BS 102. For example, the network interface 118 can be configured to support Internet or WiMAX traffic. In a typical deployment, without limitation, the network interface 118 provides an 802.3 Ethernet interface so that the BS transceiver 110 can communicate with a conventional Ethernet-based computer network. In this way, the network interface 118 may include a physical interface (e.g., a mobile switching center (MSC)) for connecting to a computer network. The term "configured for" or "configured to" used herein with respect to a specific operation or function refers to a device, component, circuit, structure, machine, signal, etc., which is physically constructed, programmed, formatted and / or arranged to perform a specific operation or function. The network interface 118 can allow the BS 102 to communicate with other BSs or core networks via a wired or wireless connection.

[0035] In some arrangements, each of UE 104a and UE 104b can operate in a hybrid communication network in which the UE communicates with BS 102 and other UEs (e.g., between 104a and 104b). As described in further detail below, UE 104a and UE 104b support SL communication with other UEs and downlink / uplink communication between BS 102 and UE 104a and UE 104b. Typically, SL communication allows UE 104a and UE 104b to establish direct communication links between each other or with other UEs from different cells without requiring BS 102 to relay data between UEs.

[0036] Figure 2 is a diagram illustrating an example system 200 for SL communication according to various arrangements. Figure 2 As shown, BS210 (such as Figure 1A BS102) broadcasts a signal received by the first UE 220, the second UE 230 and the third UE 240. Figure 2 UE 220 and 230 in the figure are shown as vehicles with a vehicle communication network, and UE 240 is shown as a mobile device. As shown in SL, UE 220-240 can communicate with each other (e.g., directly send and receive) via an air interface without being forwarded by base station 210 or core network 250. This type of V2X communication is called PC5-based V2X communication or V2X SL communication.

[0037] As used herein, when two UEs 104a or 104b are in SL communication with each other via the communication channel 105 / 170, the UE transmitting data to the other UE is referred to as a transmitting (TX) UE, and the UE receiving the data is referred to as a receiving (RX) UE.

[0038] The arrangements disclosed herein relate to systems, methods, apparatuses, and non-transitory computer-readable media for SL relay communications, and in particular to improving service continuity assurance for UEs with multi-path transmission / reception in a network by providing path switching to the UEs.

[0039] In some embodiments (e.g., R17 SL relay), Uu measurement configuration and measurement report signaling procedures are performed to evaluate both relay link measurements (e.g., via communication channel 105) and Uu link measurements (e.g., via communication channels 103a and 103b). In response to determining that the configured measurement reporting criteria are met, the measurement results from the L2 U2N remote UE 104b are reported. Similarly, the Uu measurements used for the signaling procedures are used for the R18 inter-gNB path switch case. The measurement results from the L2 U2N remote UE 104b may include at least one of the following: a serving Uu link measurement result, a serving SL relay link measurement result (e.g., measuring the PC5 link quality between the remote UE 104b and its serving relay UE 104a), an intra-BS Uu measurement result (e.g., measuring the signal strength of the neighbor Uu cell of the serving BS 102), an intra-BS (e.g., internal gNB) SL relay link measurement result (e.g., measuring the PC5 link signal strength between the remote UE 104b and the candidate relay UE of the serving BS 102), an inter-BS Uu measurement result (measuring the signal strength of the neighbor Uu cell of the neighbor BS), an inter-BS SL relay link measurement result (measuring the PC5 link signal strength between the remote UE 104b and the candidate relay UE of the neighbor BS). The intra-BS or inter-BS SL relay link measurement results may include a list of candidate relay UEs, wherein the information provided for each candidate relay UE in the list includes at least one of the following: a relay UE ID, a serving cell ID of the relay UE, and a PC5 link signal strength between the remote UE and the relay UE.

[0040] In some arrangements, after receiving the measurement results from the L2 U2N remote UE 104b, the source BS 102 may determine to switch the remote UE 104b to a direct Uu link or path of the target BS, an indirect link or path of the target BS, or to a target BS having both a direct Uu link and an indirect link (e.g., multiple paths). In some examples, the source BS selects to switch the remote UE 104b to a single path (e.g., a direct path or an indirect path) of the target BS or multiple paths of the target BS (e.g., both direct paths and indirect paths).

[0041] In some examples, the source BS 102 selects to hand off the remote UE 104b to a direct path between the target BS and the remote UE 104b, and the source BS 102 selects a target BS (eg, a target cell).

[0042] In some examples, the source BS 102 chooses to switch the remote UE 104b to an indirect path between the target BS and the remote UE 104b, and the source BS 102 selects a target relay UE and sends an identifier of the target relay UE to the target BS, or the source BS 102 provides a plurality of candidate relay UEs (which are within the coverage of the target BS) to the target BS so that the target BS selects the target relay UE.

[0043] In some examples, where the source BS 102 selects to switch the remote UE 104b to multiple paths (e.g., both direct and indirect paths), the source BS 102 may provide the selected target cell ID and target relay UE to the target BS, or provide the selected target cell ID and a list of candidate relay UEs to the target BS.

[0044] In some examples, source BS 102 provides the information described herein to the target BS via a handover request message. Figure 3 3. is a diagram illustrating a handover method 300 according to various arrangements. At 310, the source BS 102 sends a handover request 310 to the target BS 302. At 320, the source BS 102 receives a handover response 320 from the target BS 302 in response to receiving the handover request 310.

[0045] In some examples, the handover request message (e.g., sent at 310) includes a target cell ID (e.g., a target Uu cell ID) that identifies the target cell. In an example where a single path at the target BS 302 is selected, the target cell ID includes a serving cell ID / cell global identifier (NCGI) of the selected target relay UE or a serving cell ID / NCGI of one or more of the candidate relay UEs. In some examples, the target cell ID is the selected target cell of the direct path in the multipath, rather than the serving cell of the target / candidate relay UE.

[0046] In some examples, where both the target cell ID and the list of candidate relay UEs are included in the handover request message, it is necessary to provide the target BS 302 with clear information about whether the source BS 102 intends to perform path switching (switching to a single path) or use multiple paths for the remote UE 104b. Therefore, the source BS 102 also indicates the path switching type to the target BS 302 via the path switching indication, which path switching type may include at least one of the following: single path switching (indicating switching to an indirect path), indirect path (indicating switching to an indirect path), multipath (indicating switching to multiple paths), path addition (indicating switching to multiple paths), direct path to indirect path switching, indirect path to indirect path switching, single path to multiple path switching, direct path to multiple path switching, indirect path to multiple path switching, multiple path to multiple path switching.

[0047] To switch to the multipath, the source BS 102 may identify a primary path (either a direct path or an indirect path) and send a primary path indication to the target BS 302 (e.g., via a handover request message at 310). In some examples, the target BS 302 may determine the primary path and notify the source BS 102 with the primary path indication (e.g., via a handover response or handover request confirmation message at 320).

[0048] Figure 4 4 is a diagram illustrating a handover method 400 according to various arrangements. At 410, the source BS 102 sends a handover request 310 to the target BS 302, the handover request including at least one of the following: a target cell ID (e.g., a target Uu cell ID), an ID of a target relay UE, an ID of each of two or more candidate relay UEs, a path switch indication, or a primary path indication. At 420, the source BS 102 receives a handover response 320 from the target BS 302 in response to receiving the handover request 310. The handover response indicates acceptance or rejection of the handover request.

[0049] In some arrangements, after receiving measurements from the L2 U2N remote UE 104b, the source BS 102 may select a target BS for the remote UE 104b, which may then determine to configure the remote UE 104b with a single direct Uu link, an indirect link, or multiple paths.

[0050] The source BS 102 may provide measurement results (related to the selected target BS) from the remote UE 104b to the target BS 302, and then the target BS 392 may configure a single direct Uu link (e.g., the target BS 302 further selects a target cell), an indirect link (e.g., the target BS 302 further selects a target relay UE), or a multipath (e.g., the target BS 302 selects a target Uu cell for a direct path and a target relay UE for an indirect path in the multipath) for the remote UE 104b. The target BS 302 may notify the source BS 102 of at least one of the following: for a single path, the target Uu cell ID and the target relay UE ID; for a multipath, the target Uu cell ID and the target relay UE ID for the multipath, and an indication of the primary path (either a direct path or an indirect path if multipath is configured).

[0051] Figure 55 is a diagram illustrating a handover method 500 according to various arrangements. At 510, the source BS 102 sends a handover request 310 to the target BS 302, the handover request including the measurements received from the remote UE 104b. At 520, the source BS 102 receives a handover response 320 from the target BS 302 in response to receiving the handover request 310. The handover response includes at least one of the following: a target cell ID (e.g., a target Uu cell ID), an ID of a target relay UE, a path switch indication, or a primary path indication.

[0052] In a CU-DU separation implementation, a BS-CU (e.g., a gNB-CU) may notify a BS-DU (e.g., a gNB-DU) of at least one of a path switching type information or a primary path indication via an F1 interface. In some examples, the source BS 102 includes a CU and a DU. The CU of the source BS 102 may determine at least one of a path switching type or a primary path indication in a manner described herein and send it to the DU of the source BS 102 via the F1 interface. In some examples, the target BS 302 includes a CU and a DU. The CU of the target BS 302 may determine at least one of a path switching type or a primary path indication and send it to the DU of the target BS 302 via the F1 interface.

[0053] In some arrangements, the multipath configuration may trigger a relay UE in idle / inactive mode to enter connected mode.L2 U2N remote UE 104b may initially connect to CN 108 via a direct path to BS 102, and an indirect path from remote UE 104b to BS 102 may be added. Figure 6 is a diagram illustrating an example method 600 for adding an indirect path in addition to a direct path according to various arrangements. Before the communication channel 105 is established, the relay UE 602 may be the UE 104a. The method 600 attempts to establish the communication channel 105 in addition to the communication link 103b.

[0054] At 610, after the remote UE 104b measures / discovers at least one candidate relay UE, the remote UE 104b (e.g., a U2N remote UE) reports one or more candidate relay UEs (e.g., at least one U2N relay UE). At 620, the BS 102 determines to add an indirect path for the remote UE 104b via the relay UE 602, which is one of the at least one candidate relay UE. In some examples, the relay UE 602 is in an RRC idle / inactive state. At 630, the BS 102 sends an RRC reconfiguration message (e.g., an RRCReconfiguration message) to the remote UE 104b. The RRC reconfiguration message may include at least a U2N relay UE ID (e.g., an ID of the relay UE 602), a PC5 relay RLC channel configuration for relay traffic, and an associated indirect / separate bearer configuration of the SL communication channel 105 between the remote UE 104b and the relay UE 602, etc. At 640 , the remote UE 104 b establishes a PC5 connection with the relay UE 602 using the relay UE ID and the relay RLC channel configuration.

[0055] In addition, the remote UE 104b sends an RRC reconfiguration completion message to the BS 102. In some examples, the remote UE 104b may send an RRC reconfiguration completion message via an indirect path (including 650a and 650b). That is, at 650a, the remote UE 104b sends an RRC reconfiguration completion message to the relay UE 602, and at 650b, the relay UE 602 sends an RRC reconfiguration message to the BS 102. Alternatively, the remote UE 104b may send an RRC reconfiguration completion message (650c) via a direct path. That is, at 650c, the remote UE 104b directly sends an RRC reconfiguration message to the BS 102. In the example where the relay UE 602 is in an RRC idle / inactive state, the BS 102 triggers the relay UE 602 to enter an RRC connected state to support multipath transmission / reception of the remote UE 104b.

[0056] In some arrangements, the BS 102 may instruct or configure the remote UE 104b to send an RRC reconfiguration complete message via an indirect path (e.g., 650a and 650b) or a direct path (e.g., 650c). Such indication information may be included in the RRC reconfiguration message 630. In some examples, the indication information includes one of SRB1 via a direct path or SRB1 via an indirect path. In response to the remote UE 104b receiving SRB1 via the direct path between the remote UE 104b and the BS 102, the remote UE 104b sends an RRC reconfiguration complete message via the direct path. In response to the remote UE 104b receiving SRB1 via the indirect path between the remote UE 104b and the BS 102, the remote UE 104b sends an RRC reconfiguration complete message via the indirect path.

[0057] In the example where the remote UE 104b is configured to send the RRC reconfiguration complete message via an indirect path (SL communication channel), in response to receiving the RRC reconfiguration complete message from the remote UE 104b, the relay UE 602 is triggered to enter the RRC connected state and forward the RRC reconfiguration complete message to BS 102.

[0058] In an example where the remote UE 104b is configured to send an RRC reconfiguration complete message via a direct path, at 640, in response to receiving a trigger indication from the remote UE, the relay UE 602 is triggered to enter the RRC connected state. That is, after receiving a PC5 link establishment request message or a PC5 RRC reconfiguration message or other PC5 message including a trigger indication from the remote UE 104b, the relay UE 602 is aware that the relay UE 602 initiates an RRC establishment / recovery process to enter the RRC connected state. In this case, the remote UE 104b can send an indication to the relay UE 602 to trigger the relay UE to enter the RRC connected state. The indication information may include at least one of the following: a multipath indication, a path addition indication, a relay communication indication, an indication to enter the RRC connected state, a trigger to enter the RRC connected state, etc.

[0059] In some examples, where the remote UE 104b is initially connected to the CN 108 via a direct path, an indirect path is added according to method 600. After a period of time, the measurement results of the indirect path are no longer acceptable, and / or the Quality of Service (QoS) flow of the remote UE 104b does not require multipath transmission on the indirect path. In this case, the BS 102 can release the indirect path. Considering that the remote UE 104b is initially connected to the CN 108 via a direct path, the Cell Radio Network Temporary Identifier (C-RNTI) is allocated by the cell via the direct path. The cell is also regarded as a Primary Secondary Cell (PScell) by the remote UE 104b. The release of the indirect path does not affect the Primary Cell (PCell) and the corresponding C-RNTI. On the other hand, in an example where the remote UE is initially connected to the network via an indirect path and a direct path is added. The cell of the indirect path is regarded as a PCell, and the C-RNTI is also allocated by the PCell. During the release of the indirect path, the PCell of the remote UE 104b is changed to the cell of the direct path. In this case, the C-RNTI allocated by the cell of the direct path is configured to the remote UE 104b by the BS 102. This can be configured during the indirect path release process or allocated in response to adding the direct path.

[0060] In some examples where the serving cells of the direct path and the indirect path belong to the same DU, only one C-RNTI needs to be allocated. In examples where the serving cells of the direct path and the indirect path belong to different DUs, two C-RNTIs may be allocated to the remote UE 104b. In response to adding a new path for the remote UE 104b, whether a new C-RNTI is allocated to the remote UE 104b depends on whether the new serving cell belongs to another DU associated with the newly added path. Accordingly, if the paths are associated with different DUs, the release of a given path may remove the C-RNTI. Otherwise, only the path and the corresponding cell are removed, and the C-RNTI is retained.

[0061] Fig. 7A700a is a diagram illustrating an example intra-cell multipath scenario 700a according to various arrangements. BS 102 may provide coverage within a cell 710. UE 104a and UE 104b may be camped within the cell 710. A remote UE 104b may directly access the cell 710 and the BS 102 via a direct path including a communication channel 712b. The remote UE 104b may also indirectly access the cell 710 and the BS 102 via a SL communication channel 715 and the communication channel 712a. The SL communication channel 715 may be referred to as a PC5 or internal connection. UE 104b may be connected to the BS 102 via intra-cell multipath communication.

[0062] Figure 7B 700b is a diagram illustrating an example inter-cell multipath scenario 700b according to various arrangements. BS102 may provide coverage within cells 710a and 720b. UE 104a may be camped within cell 720a. UE 104b may be camped within cell 720b. Remote UE 104b may directly access cell 720b and BS102 via a direct path including communication channel 722b. Remote UE 104b may also indirectly access cell 720a and BS102 via SL communication channel 725 and communication channel 722a. SL communication channel 725 may be referred to as PC5 or internal connection. UE 104b may be connected to BS102 via inter-cell multipath communication.

[0063] In some arrangements, emergency services are defined as citizen-to-authority services, and it is up to the national authorities to decide whether the network accepts emergency calls, for example, only for valid UEs, or for UEs without a Subscriber Identity Module (SIM), Universal Subscriber Identity Module (USIM), Internet Protocol (IP) Multimedia Services Identity Module (ISIM). In 5G ProSe UE-to-network relay, an emergency request from a remote UE 104b means that the relay UE 602 needs to be responsible for the emergency services of the remote UE 104b.

[0064] When the connection of the 5G ProSe Layer-2 UE to the network relay is established for emergency services, especially when the 5G ProSe Layer-2 UE to the network relay is under congestion control and mobility restriction, the relay UE 602 ensures that the traffic and signaling of the 5G ProSe Layer-2 remote UE 104b are related to the emergency services. In order to ensure that the traffic and signaling of the 5G ProSe Layer-2 remote UE (e.g., UE 104b) are related to the emergency services, the Radio Access Network (RAN) (e.g., BS) can notify the access and mobility management function (AMF) of the remote UE 104b: the remote UE 104b is only allowed to perform emergency services. In some examples, the notification information may include at least one of the following: an emergency service indication, an indication that only emergency services are allowed, a resource restriction indication, a remote UE indication, etc. The notification information can be sent from the BS to the AMF via an initial UE message, a UE context setup / modification response message, a RAN configuration update message, or a new NG Application Protocol (NGAP) message.

[0065] Figure 8 8 is a flow chart illustrating an example method 800 for managing SL communications according to various arrangements. At 810, a first BS (e.g., a serving BS) receives measurements from a remote UE. The remote UE is communicating with the first BS via an indirect path including a first SL between the remote UE and a first relay UE or a direct path between the remote UE and the first BS. At 820, a communication method is selected based on the measurements. The communication method includes one of: 1) the remote UE communicates with a second BS (e.g., a target BS) using a direct path between the remote UE and the second BS; 2) the remote UE communicates with the second BS using an indirect path between the remote UE and the second BS, the indirect path including a second SL between the remote UE and the second relay UE; or 3) the remote UE communicates with the second BS using both a direct path and an indirect path.

[0066] In some examples, selecting a communication method 800 includes selecting, by the first BS, a communication method based on measurements.

[0067] In some examples, selecting a communication method includes selecting a second BS by a first BS, and selecting a communication method by the second BS based on measurements. The method also includes sending a handover request by the first BS to the second BS, the handover request including measurements received from a remote wireless communication device, and receiving a handover response by the first BS from the second BS. The handover response includes at least one of the following: 1) a target cell ID, the target cell ID including an ID of a serving cell of the second relay UE (e.g., a serving cell ID or NCGI) or an ID of a serving cell of a direct path; 2) an ID of the second relay UE; 3) a path switching indication indicating a path switching type of a single path or multiple paths; or 4) a primary path indication indicating one of a direct path or an indirect path as a primary path.

[0068] In some arrangements, the method 800 includes determining, by a CU of the BS, a path switch type, and sending, by the CU of the BS, the path switch type to a DU of the BS. The BS is a first BS or a second BS.

[0069] In some arrangements, the measurements include at least one of: serving Uu link measurements, serving SL relay link measurements, intra-BS Uu measurements, intra-BS SL relay link measurements, inter-BS Uu measurements, or inter-BS SL relay link measurements.

[0070] Fig. 9 9 is a flow chart illustrating an example method 900 for managing SL communications according to various arrangements. At 910, a first BS (source BS) sends a handover request including a target cell ID to a second BS (target BS). A remote UE is communicating with the first BS via a first indirect path including a first SL between the remote UE and a first relay UE or a first direct path between the remote UE and the first BS. The target cell ID includes an ID of a serving cell of the second relay UE (e.g., a serving cell ID or NCGI) or an ID of a serving cell of the direct path. At 920, the first BS receives a handover response from the second BS.

[0071] In some examples, the handover request also includes a list of candidate relay UEs and a path exchange indication. The path exchange indication indicates at least one of the path exchange types, the path exchange type including single path, indirect path, multi-path, path addition, direct path to indirect path exchange, indirect path to indirect path exchange, single path to multi-path exchange, direct path to multi-path exchange, indirect path to multi-path exchange, or multi-path to multi-path exchange. In some examples, the second BS selects a target relay UE from the list of second relay UEs and candidate relay UEs. The target relay UE is identified in the handover response.

[0072] The handover request also includes a primary path indication indicating one of a second direct path between the remote UE and the second BS or a second indirect path including a second SL between the remote UE and the second relay UE as the primary path. The handover response includes a primary path indication indicating one of the second direct path or the second indirect path as the primary path.

[0073] Fig.10 1 is a flow chart illustrating an example method 1000 for managing SL communication according to various arrangements. At 1010, a first UE (e.g., a remote UE) receives an ID of a second UE (e.g., a relay UE) and a channel configuration of a SL communication channel between the first UE and the second UE from a BS via a direct path. At 1020, the first UE establishes a SL communication channel with the second UE using the ID of the second UE and the channel configuration.

[0074] In some examples, the ID of the second UE and the channel configuration are received by the first UE in an RRC reconfiguration message.Method 1000 includes sending, by the first UE, an RRC reconfiguration complete message to the BS via a direct path or an indirect path including a SL communication channel.

[0075] In some examples, the first UE receives indication information indicating whether the RRC reconfiguration complete message is to be sent via a direct path or via an indirect path including a SL communication channel.

[0076] In some examples, the first UE sends indication information to the second UE, which triggers the second UE to enter the RRC connected state. The indication information includes at least one of the following: a multipath indication, a path addition indication, a relay communication indication, an indication of entering the RRC connected state, or a trigger of entering the RRC connected state.

[0077] In some examples, after the SL communication channel is established, the original or initial direct path is released (e.g., due to poor link quality, etc.). Thereafter, if the Uu link is satisfied and high throughput, high reliability, low latency, or high QoS service is required, a direct path between the first UE and the BS is added after the SL communication channel is established. In some examples, during a release process for releasing an indirect path including the SL communication channel or during a direct path addition process, the first UE receives a C-RNTI of a cell corresponding to the direct path from the BS.

[0078] In some examples, method 1000 also includes communicating with the CU of the BS using a direct path corresponding to the first DU by the first UE, and adding an indirect path corresponding to the second DU, the indirect path including an SL communication channel, and when the first DU and the second DU are different, the second DU allocates a C-RNTI corresponding to the indirect path to the first UE. In some examples, method 1000 also includes communicating with the CU of the BS using an indirect path corresponding to the first DU by the first UE, and adding a direct path corresponding to the second DU. The indirect path includes an SL communication channel, and when the first DU and the second DU are different, the second DU allocates a C-RNTI corresponding to the indirect path to the first UE.

[0079] In some examples, method 1000 also includes communicating with the CU by the first UE using a direct path corresponding to the first DU and an indirect path corresponding to the second DU, the indirect path including the SL communication channel. Method 1000 also includes, in response to determining that the first DU and the second DU are different, releasing one of the direct path or the indirect path for the first UE by the BS, and removing the C-RNTI corresponding to one of the direct path or the indirect path for the first UE by the BS.

[0080] In some examples, method 1000 also includes sending notification information by the BS to the AMF of the first UE, indicating that the AMF is allowed to provide emergency services only for the first UE, and the notification information includes one of an emergency service indication, an indication allowing emergency services only, a resource limitation indication, or a remote UE indication.

[0081] Although various arrangements of the present solution have been described above, it should be understood that they are presented only as examples and not limitations. Similarly, various figures can depict example architectures or configurations, which are provided to enable those of ordinary skill in the art to understand the example features and functions of the present solution. However, these people will understand that the solution is not limited to the example architectures or configurations shown, but can be implemented using various alternative architectures and configurations. In addition, as will be understood by those of ordinary skill in the art, one or more features in some arrangements can be combined with one or more features of another arrangement described herein. Therefore, the breadth and scope of the present disclosure should not be limited by any of the above-mentioned illustrative arrangements.

[0082] It should also be understood that any reference to an element using names such as "first" or "second" herein does not generally limit the number or order of these elements. Instead, these names can be used herein as a convenient means of distinguishing between two or more elements or element instances. Therefore, referring to a first and a second element does not mean that only two elements can be used, nor does it mean that the first element must precede the second element in some way.

[0083] In addition, those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, and symbols that may be referenced in the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0084] Those of ordinary skill in the art will further understand that any of the various illustrative logic blocks, modules, processors, devices, circuits, methods, and functions described in conjunction with the aspects disclosed herein may be implemented by electronic hardware (e.g., digital implementation, analog implementation, or a combination of the two), firmware, various forms of programs or design codes containing instructions (for convenience, this document may be referred to as "software" or "software modules"), or any combination of these technologies. In order to clearly illustrate this interchangeability of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been generally described above according to their functions. Such functions are implemented as hardware, firmware, software, or a combination of these technologies, depending on the specific application and the design constraints imposed on the entire system. Those skilled in the art may implement the described functions in various ways for each specific application, but such implementation decisions will not deviate from the scope of this disclosure.

[0085] In addition, it will be understood by those of ordinary skill in the art that the various illustrative logic blocks, modules, devices, components, and circuits described herein may be implemented or performed within an integrated circuit (IC), which may include a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, or any combination thereof. The logic blocks, modules, and circuits may also include antennas and / or transceivers to communicate with various components within a network or device. A general-purpose processor may be a microprocessor, but alternatively, the processor may also be any conventional processor, controller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other suitable configuration for performing the functions described herein.

[0086] If implemented in software, these functions can be stored as one or more instructions or codes on a computer-readable medium. Therefore, the steps of the method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media include both computer storage media and communication media, including any medium that can transfer a computer program or code from one place to another. The storage medium can be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, or any other medium that can be used to store the required program code in the form of instructions or data structures and can be accessed by a computer.

[0087] In this document, the term "module" as used herein refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. In addition, for the purpose of discussion, various modules are described as discrete modules; however, as will be apparent to one of ordinary skill in the art, two or more modules may be combined to form a single module that performs associated functions according to the arrangement of the present solution.

[0088] In addition, memory or other storage and communication components can be used in the arrangement of the present solution. It should be understood that, for the sake of clarity, the above description has described the arrangement of the present solution with reference to different functional units and processors. However, it is obvious that any suitable functional distribution between different functional units, processing logic elements or domains can be used without detracting from the present solution. For example, the functions shown as being performed by a separate processing logic element or controller can be performed by the same processing logic element or controller. Therefore, reference to a specific functional unit is only a reference to a suitable means for providing the described functions, rather than an indication of a strict logical or physical structure or organization.

[0089] Various modifications to the embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the embodiments shown herein, but should be given the widest scope consistent with the novel features and principles disclosed herein, as described in the following claims.

Claims

1. A wireless communication method, include: receiving, by a first base station (BS), measurements from a remote wireless communication device communicating with the first BS via an indirect path including a first side link (SL) between the remote wireless communication device and a first relay wireless communication device or a direct path between the remote wireless communication device and the first BS; and A communication method is selected based on the measurements, the communication method comprising one of: the remote wireless communication device communicating with the second BS using a direct path between the remote wireless communication device and the second BS; The remote wireless communication device communicates with the second BS using an indirect path between the remote wireless communication device and the second BS, the indirect path including a second SL between the remote wireless communication device and a second relay wireless communication device; or The remote wireless communication device communicates with the second BS using both the direct path and the indirect path.

2. The method according to claim 1, in, Selecting the communication method includes selecting, by the first BS, the communication method based on the measurements.

3. The method according to claim 1, in, Selecting the communication method includes: selecting, by the first BS, the second BS; and The communication method is selected by the second BS based on the measurements.

4. The method according to claim 3, include: sending, by the first BS to the second BS, a handover request including measurements received from the remote wireless communication device; as well as receiving, by the first BS, a handover response from the second BS, wherein the handover response includes at least one of: a target cell identifier (ID), wherein the target cell ID comprises an ID of a serving cell of the second relay wireless communication device or a serving cell of the direct path; The ID of the second relay wireless communication device; A path switching indication, wherein the path switching indication indicates a path switching type of a single path or a multi-path; or A primary path indication indicates that one of the direct path or the indirect path serves as a primary path.

5. The method according to claim 1, include: The path switching type is determined by the centralized unit (CU) of the BS; as well as The path switch type is sent by a CU of the BS to a distributed unit (DU) of the BS, wherein the BS is the first BS or the second BS.

6. The method according to claim 1, in, The measurements include at least one of: Service Uu link measurement results; Service SL relay link measurement results; Uu measurement results within BS; Measurement results of SL relay links within the BS; Inter-BS Uu measurement results; or Inter-BS SL relay link measurement results. 7 . A wireless communication device, comprising at least one processor and a memory, wherein the at least one processor is configured to read a code from the memory and implement the method according to claim 1 .

8. A computer program product comprising computer readable program medium code stored thereon, which, when executed by at least one processor, causes the at least one processor to implement the method according to claim 1.

9. A wireless communication method, include: sending, by a first base station (BS), a handover request including a target cell identifier (ID) to a second BS, wherein a remote wireless communication device communicates with the first BS via a first indirect path including a first side link (SL) between the remote wireless communication device and a first relay wireless communication device or a first direct path between the remote wireless communication device and the first BS, wherein the target cell ID includes an ID of a serving cell of the second relay wireless communication device or a serving cell of the direct path; and A handover response is received by the first BS from the second BS.

10. The method according to claim 9, in, The handover request further includes at least one of the following: a list of candidate relay wireless communication devices or a path switching indication, wherein the path switching indication indicates at least one of the following path switching types: Single path; Indirect path; Multipath; Path added; Direct path to indirect path switching; Indirect path to indirect path switching; Single-path to multi-path switching; Direct path to multipath switching; Indirect path to multipath switching; or Multipath to multipath switching.

11. The method according to claim 10, in, The second BS selects a target relay wireless communication device from the second relay wireless communication device and the list of candidate relay wireless communication devices, the target relay wireless communication device being identified in the handover response.

12. The method according to claim 9, wherein The handover request further includes a primary path indication indicating one of a second direct path between the remote wireless communication device and the second BS or a second indirect path including a second SL between the remote wireless communication device and the second relay wireless communication device as a primary path; or The switching response includes the primary path indication indicating one of the second direct path or the second indirect path as the primary path.

13. A wireless communication device, comprising at least one processor and a memory, wherein the at least one processor is configured to read a code from the memory and implement the method according to claim 9.

14. A computer program product comprising computer readable program medium code stored thereon, which, when executed by at least one processor, causes the at least one processor to implement the method according to claim 9.

15. A wireless communication method, include: receiving, by a first wireless communication device, an identifier (ID) of a second wireless communication device and a channel configuration for a sidelink (SL) communication channel between the first wireless communication device and the second wireless communication device from a base station (BS) via a direct path; The first wireless communication device establishes the SL communication channel with the second wireless communication device using the ID of the second wireless communication device and the channel configuration.

16. The method according to claim 15, wherein The ID of the second wireless communication device and the channel configuration are received by the first wireless communication device in a radio resource control (RRC) reconfiguration message; and The method includes sending, by the first wireless communication device, an RRC reconfiguration complete message to the BS via the direct path or an indirect path including the SL communication channel.

17. The method of claim 15, comprising receiving, by the first wireless communication device, indication information indicating whether the RRC reconfiguration complete message is to be sent via the direct path or via an indirect path including the SL communication channel.

18. The method of claim 15, comprising sending, by the first wireless communication device, indication information to the second wireless communication device, the indication information triggering the second wireless communication device to enter a radio resource control (RRC) connected state.

19. The method according to claim 18, in, The indication information includes at least one of the following: Multipath indication; Path addition instructions; Relay communication instructions; Entering RRC connection state indication; or Trigger for entering RRC connected state.

20. The method according to claim 15, include: communicating, by the first wireless communication device, with a centralized unit (CU) of the BS using one of a direct path corresponding to a first distributed unit (DU) or an indirect path corresponding to a second DU, the indirect path including the SL communication channel; A cell radio network temporary identifier (C-RNTI) corresponding to an indirect path including the SL communication channel is allocated to the first wireless communication device by the second DU, wherein the first DU and the second DU are different.

21. The method according to claim 15, include: communicating, by the first wireless communication device, with a centralized unit (CU) using a direct path corresponding to a first distributed unit (DU) and an indirect path corresponding to a second DU, the indirect path including the SL communication channel; releasing, by the BS, one of the direct path or the indirect path for the first wireless communication device; In response to determining that the first DU and the second DU are different, a cell radio network temporary identifier (C-RNTI) corresponding to one of the direct path or the indirect path is removed by the BS for the first wireless communication device.

22. According to the method according to claim 15, the BS sends a notification message to the mobility management function (AMF) of the first wireless communication device, and the notification message indicates that the AMF is allowed to provide emergency services only to the first wireless communication device, and the notification message includes one of an emergency service indication, an indication of allowing emergency services only, a resource limitation indication or a remote user equipment (UE) indication.

23. A wireless communication device comprising at least one processor and a memory, wherein the at least one processor is configured to read code from the memory and implement the method according to claim 15.

24. A computer program product comprising computer readable program medium code stored thereon, which, when executed by at least one processor, causes the at least one processor to implement the method of claim 15.

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