CN117596645A - Design for 3GPP R18 multipath - Google Patents

Abstract

To designs for 3gpp r18 multipath. Aspects of the present disclosure provide methods for a first User Equipment (UE) having a first path to a network to add to a second path of the network. For example, the method may include: a first Radio Resource Control (RRC) message to add a second path is received from the network at a first UE. The method may also include configuring, by the first UE, the second path based on the first RRC message.

Description

Design for 3GPP R18 multipath

Cross Reference to Related Applications

The present application claims priority from PCT application No. PCT/CN2022/113322, entitled "AN EXTENSIVE SYSTEM ARCHITECTURE TO SUPPORT MULTI-PATCONFIGURATION" filed on month 8, 2022, 18, and PCT application No. PCT/CN2022/113385, entitled "METHOD OF PATH ADDITION AND REMOVAL TO SUPPORT MULTI-PATCONFIGURATION", filed on month 8, 2022, 18, which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates to wireless communications, and more particularly, to methods and apparatus for adding and removing second paths to support multipath configuration.

Background

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

L2 relay and L3 relay

In order to extend network coverage, various relay technologies have been developed. Relay nodes may be used to forward packets/signals between network nodes (e.g., base Stations (BSs), transmission and Reception Points (TRPs)) and User Equipments (UEs).

The relay node may be a network vendor deployed infrastructure such as a Long Term Evolution (LTE) relay node and a New Radio (NR) Integrated Access and Backhaul (IAB) node specified since 3gpp r 16. These types of relay nodes are controlled by the network and may be transparent to the UE.

The relay node may also be a user-deployed relay, e.g. using a UE as a relay (referred to as UE relay). Such relay nodes have a more limited transmit/receive capability in forwarding traffic flows than IABs. However, it has the advantage of supporting low cost and dynamic/flexible deployment. Extending network coverage using UE relay is referred to as UE-to-network relay (or UE-to-NW relay or U2N relay).

In a 3GPP context, a relay UE uses side uplink (SL, different from Uplink (UL) and Downlink (DL)) resources to communicate with a remote UE (or source UE, which is the source of traffic flows to be forwarded). Therefore, in 3GPP, UE-to-NW relay is also called SL relay.

To support side-uplink relay, there are two UE-to-NW relay architectures, namely layer 2 relay (L2 relay) and layer 3 relay (L3 relay).

The L3-based side-uplink relay UE forwards the data packet stream of the remote UE as an IP traffic stream as a general router in the data communication network. Forwarding based on IP traffic flows is done in a best effort manner. For L3 UE to NW relay, there are both side uplink radio bearers (SLRBs) located on the PC5 interface and Uu radio bearers carrying quality of service (QoS) flows established between the remote UE and a core network such as a fifth generation core (5 GC). In converting the PC5 flow to Uu flow, the L3 UE-to-NW relay may support flow-based mapping at the traffic data adaptation protocol (SDAP) sublayer and the same holds true during traffic flow forwarding. Note that since the L3-based side-uplink relay UE works like an IP router, the remote UE is transparent to the base station, i.e. the base station cannot know whether the traffic flow sent by the relay UE originates from the relay UE itself or from the remote UE but is forwarded by the relay UE.

In contrast, in the case of L2-based SL relay, relay is performed between the remote UE and the network over a Radio Link Control (RLC) sublayer via the relay UE for both the Control Plane (CP) and the User Plane (UP). Uu SDAP/Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) terminate between the remote UE and the gNB, while RLC, medium Access Control (MAC) and physical layer (PHY) terminate in respective links, i.e., links between the remote UE and the UE-to-NW relay UE and links between the UE-to-NW relay UE and the gNB.

The adaptation layer on the RLC layer is supported in Uu to perform bearer mapping and may also be placed on a device-to-device interface such as a PC5 interface to perform bearer mapping at the side link. The adaptation layer between the relay UE and the gNB can distinguish between multiple bearers (e.g., signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs)) of a particular remote UE. Within the Uu DRB, different remote UEs and different bearers of the remote UEs may be indicated by additional information included in the adaptation layer header. Unlike L3 relay, in L2 relay, the base station knows the individual remote UEs, so the end-to-end connection between the remote UE and the base station should be established first before the relay UE starts forwarding the normal data traffic. After establishing the RRC connection via SL relay, the remote UE may then forward the data traffic flow based on the established bearer and forwarding/router information carried in the adaptation layer.

Relay selection

In 3GPP R17, side-uplink relay is supported to enable network coverage extension. To extend network coverage, reference Signal Received Power (RSRP) criteria exist to determine whether a UE may act as a relay UE or a remote UE.

In particular, in the 3gpp r17 specification for SL relay, it is specified that the remote UE should have a measured Uu Reference Signal Received Power (RSRP) below the RSRP threshold (threshHighRemote). This means that the UE can request assistance for traffic forwarding only if the UE has a very poor Uu RSRP. Furthermore, the UE may act as a relay UE only if its Uu RSRP is above the RSRP threshold (threshLowRelay). This means that a UE can help other UEs forward traffic only if the UE has good Uu link quality. Furthermore, the UE may be a relay UE only if its Uu RSRP is below another RSRP threshold (referred to as threshHighRelay), which threshold is used to prevent the cell-center UE from becoming a relay. Otherwise, if the relay UE is in the cell center and the remote UE is at the cell edge, the remote UE will transmit with very high power to communicate with the cell center UE, causing significant interference to its neighboring UEs. Finally, there is a side-uplink RSRP threshold (sl-RSRP-Thresh) for measuring the side-link quality between the remote UE and the relay UE. If the SL RSRP between the remote UE and the relay UE is below a threshold, the side-link towards the relay UE is considered too poor to support satisfactory relay performance.

When the UE meets the remote UE criteria (Uu RSRP is lower than threshHighRemote), a decision is made by the UE implementation to perform cell reselection or relay selection.

Single-path relay and multi-path relay

Note that in 3gpp r17, only single path UE to NW relay is supported. That is, the UE may choose a direct path (i.e., directly connected to the gNB via a Uu link) or an indirect path (i.e., connected to the gNB via traffic forwarding by the relay UE), rather than both. Furthermore, 3gpp r17 only supports single hop UE to NW relay. Support for multi-hop UE to NW relay is left to future releases.

To further extend the UE to NW relay, multi-hop and multi-path aspects are considered. Multi-hop relay, obviously, can help eliminate deep coverage dead zones. In contrast, multipath relay allows multiple traffic flow forwarding paths from source to destination, which does increase transmission reliability and is also beneficial to the throughput of remote UEs.

Disclosure of Invention

Aspects of the present disclosure provide a method for a first User Equipment (UE) having a first path to a network to add to a second path of the network. For example, the method may include: receiving, at the first UE, a first Radio Resource Control (RRC) message from the network to add the second path; and configuring, by the first UE, a second path based on the first RRC message.

In an embodiment, the first path may be an indirect path of the first UE to the network via a second UE, the second path may be a direct path of the first UE to the network, and the first UE and the second UE may have a serving cell belonging to the network. In an embodiment, the method may further comprise: when a measurement event occurs, the first UE sends a measurement report to the network. For example, the measurement event may occur when the serving cell of the second UE is better than a first threshold and the serving cell of the first UE becomes better than a second threshold. In an embodiment, configuring, by the first UE, the second path based on the first RRC message may include: performing a cell (re) selection procedure to evaluate candidate serving cells for adding the direct path; and setting the candidate serving cell as a primary cell (PCell) of the first UE. In another embodiment, configuring, by the first UE, the second path based on the first RRC message may include: a secondary cell (SCell) addition procedure is performed to add the serving cell of the first UE as a direct path for the first UE.

In an embodiment, the first path may be a direct path of the first UE to the network, the second path may be an indirect path of the first UE to the network via a second UE, and the first UE and the second UE may have a serving cell belonging to the network. In an embodiment, the method may further comprise: when a measurement event occurs, the first UE sends a measurement report to the network. For example, the measurement event may occur when the serving cell of the first UE is better than a first threshold and the serving cell of the second UE becomes better than a second threshold. In an embodiment, configuring, by the first UE, the second path based on the first RRC message may include: performing a relay selection procedure to evaluate candidate relay UEs for adding the indirect path; and setting the candidate relay UE as a second UE in an indirect path of the first UE. In another embodiment, configuring, by the first UE, the second path based on the first RRC message may include: a cell addition procedure is performed to add a serving cell of the second UE as the indirect path for the first UE.

In an embodiment, performing the cell addition procedure may include: a report is sent by the first UE to the network when a list of candidate relay UEs meeting criteria for adding the indirect path is updated. The report may be sent, for example, by a ueassanceinformation message or a sidinkueinformation message. In an embodiment, the method may further include receiving a second RRC message to configure the indirect path.

Aspects of the present disclosure also provide a method for a first UE having a first path to a network and a second path to the network. For example, the method may include receiving, at a first UE, a Radio Resource Control (RRC) message from a network to remove a second path; and removing, by the first UE, a second path based on the RRC message.

In an embodiment, the first path may be an indirect path of the first UE to the network via a second UE, the second path may be a direct path of the first UE to the network, and the first UE and the second UE may have a serving cell belonging to the network. In an embodiment, the method may further comprise: when a measurement event occurs, the first UE sends a measurement report to the network. For example, the measurement event may occur when the serving cell of the second UE is better than a first threshold and the serving cell of the first UE becomes worse than a second threshold.

In an embodiment, the first path may be a direct path of the first UE to the network, the second path is an indirect path of the first UE to the network via a second UE, and the first UE and the second UE may have a serving cell belonging to the network. In an embodiment, the method may further comprise: when a measurement event occurs, a measurement report is sent by the first UE to the network. For example, the measurement event may occur when the serving cell of the second UE is better than a first threshold and the serving cell of the first UE is worse than a second threshold.

Methods are provided to support system architecture when configuring multipath for a remote UE.

In a novel aspect, it is proposed how to model two paths of a remote UE when the remote UE and a selected relay UE are configured with (1) the same gNB and the same serving cell, (2) the same gNB but different serving cells, and (3) different gnbs.

In a novel aspect, it is proposed how a remote UE determines its PCell when configuring multipath.

In a novel aspect, it is proposed how a remote UE monitors paging messages when configuring multipath, and a relay UE may help forward paging messages.

In a novel aspect, it is proposed how a remote UE receives system information when configuring multipath, and a relay UE may help forward the system information.

Aspects of the present disclosure also provide an apparatus having a direct path to a network. For example, the apparatus may include a processor configured to perform a method for the apparatus that adds to and removes from a network a second path. In an embodiment, the method may comprise the steps of: receiving a first Radio Resource Control (RRC) message from the network to add the second path; and configuring the second path based on the first RRC message. In an embodiment, the method may further comprise: receiving a second RRC message from the network to remove the second path; and removing the second path based on the second RRC message.

Methods are provided for establishing a second path towards a network for a UE supporting multipath configuration.

In an aspect, the remote UE performs measurements on the candidate serving cell and/or the candidate relay UE when the first path has been established and is operating normally and the remote UE is multipath enabled.

In an aspect, the remote UE performs measurement reporting upon occurrence of one or more measurement events specific to multipath.

In an aspect, the new event triggering measurement reporting for multipath is when PCell becomes better than threshold 1 and candidate L2U 2N relay UE becomes better than threshold 2.

In an embodiment, the new event triggering measurement reporting for multipath is when the serving L2U 2N relay UE becomes better than threshold 1 and the NR cell becomes better than threshold 2.

In an embodiment, the new event triggering measurement reporting for multipath is when the serving L2U 2N relay UE becomes better than threshold 1 and the candidate L2U 2N relay UE becomes better than threshold 2.

In an aspect, based on the measurement report, the gNB sends an RRC message via the existing path to reconfigure the second path (for path addition) or to reconfigure the second path (for path removal).

Drawings

Various embodiments of the present disclosure will now be described in detail, by way of example, with reference to the following figures, in which like reference numerals refer to like elements, and in which:

fig. 1 illustrates a network topology of a remote UE configured with multiple paths (e.g., one direct path and one indirect path), where the remote UE and a relay UE select serving cells belonging to the same gNB, in accordance with some embodiments of the disclosure;

fig. 2 illustrates a network topology of a remote UE configured with multiple paths (e.g., one direct path and one indirect path), where the remote UE and a relay UE select serving cells belonging to different gnbs, according to some embodiments of the disclosure;

Fig. 3 illustrates a network topology of a remote UE configured with multiple paths (e.g., two indirect paths), where two relay UEs select serving cells belonging to the same gNB, according to some embodiments of the disclosure;

fig. 4 illustrates a network topology of a remote UE configured with multiple paths (e.g., two indirect paths), where two relay UEs select serving cells belonging to different gnbs, according to some embodiments of the disclosure;

fig. 5 illustrates an exemplary signaling procedure for a remote UE that has established an indirect path to add a second path (e.g., a direct path), in accordance with some embodiments of the present disclosure;

fig. 6 illustrates an exemplary signaling procedure for a remote UE that has established a direct path to add a second path (e.g., an indirect path), in accordance with some embodiments of the present disclosure;

fig. 6A is a flowchart of an exemplary method for a remote UE that has established a direct path to add a second path (e.g., an indirect path) in accordance with some embodiments of the present disclosure;

fig. 7 illustrates an exemplary signaling procedure for a remote UE that has established an indirect path to add a second path (e.g., a direct path), in accordance with some embodiments of the present disclosure;

Fig. 8 illustrates an exemplary signaling procedure for a remote UE that has established a direct path to add a second path (e.g., an indirect path), in accordance with some embodiments of the present disclosure;

fig. 9 illustrates an exemplary signaling procedure for a remote UE that has established a direct path to add a second path (e.g., an indirect path), in accordance with some embodiments of the present disclosure;

fig. 10 illustrates an exemplary signaling procedure for a remote UE that has established a direct path to add a second path (e.g., an indirect path), in accordance with some embodiments of the present disclosure;

fig. 11 is a flowchart of an exemplary method for a remote UE having a first path to a network and a second path to the network to remove the second path, in accordance with some embodiments of the present disclosure; and

fig. 12 is a functional block diagram of an apparatus that has had a first path including circuitry configured to perform a method for the apparatus to add a second path and remove the second path, according to some embodiments of the present disclosure.

Detailed Description

In the following description, dual paths are used as examples to explain embodiments of the present disclosure. Note that the present disclosure is not limited to the dual path case, but may extend to a multi path case in which the number of paths between the remote UE and the gNB may be equal to or greater than two.

Multipath configuration model (Primary cell (PCell) configuration, carrier Aggregation (CA)/Dual Connectivity (DC) model, paging monitoring and System information acquisition)

The architecture of the system supporting multipath depends on the relay topology. Considering a remote UE configured with two paths and a single hop relay, four possible network topologies 100 to 400 are illustrated in fig. 1 to 4, respectively.

Fig. 1 illustrates a network topology 100 of a remote UE configured with multiple paths according to some embodiments of the present disclosure. In network topology 100, remote UE 121 and relay UE 131 may select serving cells belonging to the same gNB (e.g., gNB 111). As shown in fig. 1, remote UE 121 communicates with a first serving cell of gNB 111 via direct path 141 and with a second serving cell of gNB 111 via indirect path 151 through relay UE 131. In an embodiment, the first serving cell is a second serving cell. In another embodiment, the first serving cell is different from the second serving cell.

Fig. 2 illustrates a network topology 200 of a remote UE configured with multiple paths in accordance with some embodiments of the present disclosure. In the network topology 200, the remote UE 221 and the relay UE 231 may select serving cells that respectively belong to different gnbs (e.g., the first and second gnbs 211, 212). As shown in fig. 2, the remote UE 221 communicates with a first serving cell of the first gNB 211 via a direct path 241 and communicates with a second serving cell of the second gNB 212 through the relay UE 231 via an indirect path 251.

Fig. 3 illustrates a network topology 300 of a remote UE configured with multiple paths in accordance with some embodiments of the present disclosure. In the network topology 300, the remote UE 321 and the two relay UEs (e.g., the first relay UE 331 and the second relay UE 332) may select serving cells belonging to the same gNB (e.g., the gNB 311). As shown in fig. 3, the remote UE 321 communicates with a first serving cell of the gNB 311 through a first relay UE 331 via a first indirect path 351 and communicates with a second serving cell of the gNB 311 through a second relay UE 332 via a second indirect path 352. In an embodiment, the first serving cell is a second serving cell. In another embodiment, the first serving cell is different from the second serving cell.

Fig. 4 illustrates a network topology 400 of a remote UE configured with multiple paths in accordance with some embodiments of the present disclosure. In the network topology 400, a remote UE 421 and two relay UEs (e.g., a first relay UE 431 and a second relay UE 432) may select serving cells belonging to different gnbs (e.g., a first gNB 411 and a second gNB 412), respectively. As shown in fig. 4, the remote UE 421 communicates with a first serving cell of the first gNB 411 through a first relay UE 431 via a first indirect path 451 and communicates with a second serving cell of the second gNB 412 through a second relay UE 432 via a second indirect path 452.

In the present disclosure, the description is mainly directed to the network topologies 100 and 200, but the design concept can be easily extended to the network topologies 300 and 400.

PCell configuration

In a multipath configuration, the remote UE and the relay UE may select different cells (e.g., a first cell and a second cell, respectively) for their Uu links. The problem is that the remote UE should consider the first cell or the second cell as its PCell.

In an embodiment, the remote UE may always consider the PCell in its direct Uu link. The advantage is that the use of a direct link for control signaling can reduce signaling delay and have better reliability. In this case, if the UE initially has a relay path and a direct path is added later, the network will need to reconfigure the PCell in case the relay UE and the remote UE are linked to different serving cells.

In an embodiment, whether the PCell is on the Uu link of the remote UE or on the Uu link of the relay UE may depend on the network configuration. This embodiment allows the Uu link of the remote UE to act as a secondary cell (SCell), so that existing SCell activation schemes (e.g., dormant BWP) may be reused to save power for the remote UE.

In an embodiment, the remote UE may consider the first established path as PCell. If the remote UE starts with an indirect path, the gNB may add the direct path as an SCell and vice versa. This embodiment may be the simplest alternative in terms of specification impact and gives flexibility in network determination without adding special signaling and procedures for switching which path is the PCell.

CA/DC model

For multi-path configurations, the problem is how these multiple paths (e.g., two paths) interact with each other or with the corresponding protocol stacks.

In an embodiment, if the remote UE and the relay UE are connected to the same gNB, the configuration may be considered as a multiple Component Carrier (CC) model. In the multi-CC model, when considering remote UEs configured with direct and indirect links, the remote UEs may (at least) maintain UL carriers (in their Uu links) and side-link (SL) carriers (for communication with relay UEs). From the remote UE's point of view, the two paths belong to the same RRC connection, since they terminate at the same gNB, and the remote UE uses the same (unique) C-RNTI for both paths.

In an embodiment, if the remote UE and the relay UE are connected to the same gNB and the configuration is modeled as a multi-CC model, a signaling-like Medium Access Control (MAC) Control Element (CE) controls the (de) activation of the respective paths. For example, the definition of CCs in SCell (de) activation MAC CEs may be generalized per path, and the gNB may use modified MAC CEs to put indirect paths into an active/inactive/dormant state. As another example, a new MAC CE format may be defined to control the activation/deactivation/dormant states of various indirect paths separate from the legacy SCell.

In an embodiment, if the remote UE and the relay UE are connected to the same gNB, the configuration may be considered as a multi-connection model. In the so-called multi-connection model, the remote UE may maintain separate RRC connections for both paths. The gNB may allocate different C-RNTIs for the remote UEs to manage the two paths separately.

In an embodiment, if the remote UE and the relay UE are connected to different gnbs, the remote UE may apply a DC model to handle both paths. That is, similar to the conventional DC, the remote UE may consider two paths with separate RRC/RLC/MAC layers. Traffic flows received from the two paths (for downlink) may be combined in the PDCP layer, and traffic flows transmitted may be separated in the PDCP layer. There may be separate bearers configured to enable the remote UE to send/receive traffic flows to/from different gnbs.

Paging monitoring

One discussion of supporting multipath is with respect to paging monitoring. In R17 single-hop single-path relay, the RRC IDLE/INACTIVE remote UE does not need to monitor for pages itself. The relay UE may monitor paging occasions of the remote UE or receive and forward paging notifications when dedicated RRC messages are received from the gNB.

When configuring multipath, there are a number of possible embodiments.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell, the remote UE may rely on the relay UE to forward the paging notification.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell, the remote UE may monitor the paging message itself.

In an embodiment, if the remote UE and the relay UE select the same gNB but different serving cells, the remote UE may still rely on the relay UE to forward the paging notification. That is, the conventional paging procedure of SL relay can be reused as long as the remote UE and the relay UE select the same gNB. For example, assume that the gNB will send a remote UE paging message to the relay UE via dedicated RRC signaling.

In an embodiment, if the remote UE and the relay UE select the same gNB but different serving cells, whether the remote UE monitors its own paging occasion may depend on where the PCell is located. The relay UE may monitor paging of the remote UE if the PCell is configured in the relay direct Uu link. The remote UE may monitor the paging occasion itself if the PCell is configured in a remote direct Uu link.

In an embodiment, if the remote UE and the relay UE select different gnbs, the remote UE may monitor its paging occasions for the direct link and the relay UE may help forward paging messages from the indirect path's gnbs.

In an embodiment, if the remote UE and the relay UE select different gnbs, the remote UE need not monitor for pages for the direct path. If the gNB in the direct path wishes to page the remote UE, the paging message will be redirected to the gNB in the indirect path and then forwarded to the remote UE via the relay UE.

In an embodiment, if the remote UE and the relay UE select different gnbs, the remote UE needs to monitor for pages for the direct path and the relay UE does not need to help forward the paging message. If the gNB in the indirect path wishes to page the remote UE, the paging message will be redirected to the gNB of the direct path.

System information acquisition

In conventional 3gpp r 17-side uplink relay (single path relay), the relay UE will acquire system information for the remote UE, which is useful when the remote UE is out of Uu coverage. When a remote UE is configured with multiple paths, multiple embodiments are possible as described below.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell, and the serving cell is the PCell of the remote UE, the remote UE may rely on the relay UE to acquire and forward the desired system information. That is, the remote UE does not monitor or is not requested to monitor broadcast system information of the PCell.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell, and the serving cell is the PCell of the remote UE, the remote UE may monitor the system information itself.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell and the serving cell is the PCell of the remote UE, whether the remote UE acquires system information by itself or by relay forwarding may depend on the type of system information. For example, for those system information messages related to latency critical services or functions, the remote UE may be configured to acquire them and monitor for changes via the direct Uu link.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell and the serving cell is the PCell of the remote UE, the remote UE is allowed to simultaneously acquire system information via the direct Uu link and request system information from the relay UE via the indirect path.

In an embodiment, if the remote UE and the relay UE select the same gNB and the same serving cell, and the serving cell is the PCell of the remote UE, the network may configure the remote UE to acquire system information via different manners (e.g., via direct path only, via indirect path only, via direct or indirect path, or via both direct and indirect paths) for different types/categories of system information (or System Information Blocks (SIBs)).

In an embodiment, if the remote UE and the relay UE select the same gNB but different serving cells, whether the remote UE obtains its system information via the direct Uu link may depend on where the PCell is located. If the PCell is configured in the relay direct Uu link, the relay UE will provide system information of the PCell to the remote UE. If the PCell is configured in a remote direct Uu link, the remote UE may acquire system information via the direct remote Uu link.

In an embodiment, if the remote UE and the relay UE select the same gNB but different serving cells and the PCell is configured in the direct Uu link of the remote UE, the remote UE may still rely on the relay UE to forward the system information. That is, the remote UE does not monitor its selected serving cell (PCell). In contrast, when the PCell of the remote UE updates system information, the PCell uses dedicated signaling via a direct or indirect path to provide the remote UE with updated system information or to inform the remote UE about which (interesting) system information is changed.

In an embodiment, if the remote UE and the relay UE select different gnbs, the remote UE may obtain system information from the PCell of the direct link, while the relay UE may help forward the system information from the gnbs of the indirect path.

Model for a second path

When the remote UE already has a first path (RRC connection established), there are various schemes to model the second path addition for the remote UE.

When the remote UE has established a direct path, there are various models for the remote UE to use the relay to add a second path (indirect path).

In an embodiment, if the remote UE and the relay are connected to the same BS (or TRP), the addition of the second path may be considered as SCell addition, irrespective of whether the first path of the remote UE is a direct path or an indirect path. That is, the definition of SCell addition may be extended/generalized to cover "adding an indirect path via relay".

In an embodiment, if the remote UE and the relay are connected to the same BS (or TRP), the addition of the second path may be considered as a relay addition, regardless of whether the first path is a direct path or an indirect path. The "relay add" procedure herein is somewhat different from the conventional relay selection procedure. Relay selection means that the remote UE adds a relay without an existing RRC connection between the remote UE and the gNB, and relay addition means that the remote UE adds a relay given an existing RRC connection.

In an embodiment, if the remote UE and the relay are connected to the same BS (or TRP), the addition of the second path may be considered a relay addition in case the first path is also an indirect path; otherwise, the addition of the second path may be considered a relay selection. In this embodiment, relay selection may be defined as a process by which the remote UE selects its first relay, and relay addition may be defined as a process by which the remote UE selects the second or more relays.

In an embodiment, if the remote UE and the relay are connected to the same BS (or TRP), the relay selection procedure may be re-used whenever a relay is added as a new indirect path. When the remote UE has an indirect path and wishes to add a direct path, there are also a number of ways to model the second path addition.

In an embodiment, when the remote UE wishes to add a direct path as a second (or third, etc.) path, the path addition may be modeled as an SCell addition. For example, the gNB may configure the remote UE to add NR cells via RRCReconfiguration, and may use MAC CEs to activate or deactivate the configured serving cells.

In an embodiment, when the remote UE wants to add a direct path as a second (or third, etc.) path, path addition may be considered as SCell addition if there already exists an existing direct link for the serving cell of the same gNB. Path addition may be considered cell selection if there is no direct link to the serving cell of the same gNB.

In order to determine whether to perform the procedure for the second path addition, the remote UE may need to perform measurement reporting in case a candidate cell or a candidate relay becomes available. In addition to the second path addition, the second path removal may also require measurement reporting.

The process of the second path addition can be summarized as follows:

the remote UE may perform measurements (for Uu or PC 5) according to the measurement configuration (including configured measurement events);

the remote UE can report measurement to the gNB according to the measurement result;

the gNB can decide to add the auxiliary path and send a corresponding RRC message to the remote UE (and the candidate relay UE); and

and establishing an auxiliary path.

Signaling for second path setup/removal

Fig. 5 illustrates an exemplary signaling process 500 for a remote UE that has established an indirect path to add a second path (e.g., a direct path) in accordance with some embodiments of the present disclosure. In an embodiment, the candidate cell for the remote UE in the direct path is the same as the serving cell of the relay UE in the established indirect path, as shown in fig. 1. In an embodiment, to add the direct path, the cell (re) selection or Scell addition procedure may be re-used. In step 0, before the signaling procedure 500 starts, the remote UE 121 may perform measurements on NR cells including a serving cell serving the relay UE 131. For example, the remote UE 121 (e.g., in rrc_connected mode) may measure the received power of the reference signal. The remote UE 121 will trigger the transmission of Reference Signal Received Power (RSRP) measurement reports to the network (e.g., the gNB 111) if the measurement satisfies the configuration conditions or when a measurement event occurs. In an embodiment, the measurement event may be configured by the network. The signaling process 500 may begin at step 510.

In step 510, when a measurement event occurs, the remote UE 121 may send an RSRP measurement report to the gNB 111. For example, the measurement event may occur when the remote UE 121 receives an RSRP (and/or signal to interference and noise ratio (SINR)) above a first threshold, and then the remote UE 121 will send an RSRP/SINR measurement report to the gNB 111 via relay forwarding (indicated by a circle) by the relay UE 131. That is, even when the remote UE 121 selects a serving relay (i.e., relay UE 131), the remote UE 121 may be configured using a measurement report for NE cell measurement. The signaling process 500 may then proceed to step 520.

In step 520, the network may send a trigger message to the remote UE 121 (e.g., reuse an existing message such as an RRC reconfiguration message or an application specific message to trigger the addition of the second path) to trigger the remote UE 121 to establish the second path. The signaling process 500 may then proceed to step 530.

In step 530, the remote UE 121, after receiving the trigger message, may perform a Random Access Channel (RACH) procedure to acquire UL synchronization with the gNB 111 and perform UL/DL beam alignment in the Uu link. The signaling process 500 may then proceed to step 540.

In step 540, after the remote UE 121 notifies the RACH procedure completion, the gNB 111 may send an RRC reconfiguration message to modify the RRC connection of the remote UE 121, e.g., further configure the Uu link of the remote UE 121. The signaling process 500 may then proceed to step 550.

In step 550, the remote UE 121, after configuring its Uu link, may reply to the gNB 111 with an RRC reconfiguration complete message in response to the RRC reconfiguration message.

In an embodiment, if the trigger message includes an RRC reconfiguration message, the remote UE 121 may transmit an RRC reconfiguration complete message in response to the RRC reconfiguration message, and thus steps 540 and 550 may be omitted. In another embodiment, steps 510 and 520 may be omitted if the remote UE 121 is configured to perform autonomous addition of the second path. That is, the remote UE 121 may trigger the RACH procedure to establish a Uu link as long as criteria for Uu link quality configured by the network are satisfied, considering that the NR cell has a sufficiently good Uu link quality.

Fig. 6 illustrates an exemplary signaling process 600 for a remote UE that has established a direct path to add a second path (e.g., an indirect path) in accordance with some embodiments of the present disclosure. In an embodiment, the candidate cell of the remote UE in the indirect path is the same as the serving cell of the remote UE in the established direct path, as shown in fig. 1. In an embodiment, to add an indirect path (e.g., add a new relay), the relay selection process may be reused or a new relay addition process may be performed. For example, when the relay UE to be added has a sufficiently high Uu RSRP above a threshold and a sufficiently high SL RSRP received by the remote UE, the relay selection procedure may be reused to add the relay UE. As another embodiment, when the relay UE to be added has a Uu RSRP that is better than that of the remote UE, a new relay addition procedure may be performed to add the relay UE. In an embodiment, the signaling procedure 600 may be initiated by a network (e.g., the gNB 111). In step 0, before the signaling procedure 600 begins, when the remote UE 121 already has a serving cell, the remote UE 121 may be configured to perform measurements on candidate relay UEs (e.g., on its SL-RSRP or SD-RSRP). For example, the remote UE 121 (e.g., in an rrc_connected state) may measure the received power of the reference signal. The remote UE 121 will trigger the transmission of Reference Signal Received Power (RSRP) measurement reports to the network (e.g., the gNB 111) if the measurement satisfies the configuration conditions or when a measurement event occurs. In an embodiment, the measurement event may be configured by the network. Signaling process 600 may begin at step 610.

In step 610, when a measurement event occurs, the remote UE 121 may send RSRP measurements to the gNB 111. For example, when the candidate relay has a SL-RSRP above the SL threshold and optionally the serving cell (or PCell) of the remote UE 121 has a Uu-RSRP above the Uu threshold, a measurement event may occur, and the remote UE 121 will then send a measurement report to the gNB 111. For example, the identity of the eligible candidate relay UE may be indicated in one of a measurement report message, a desiringueinformation message, or a UEAssistanceInformation message. The signaling process 600 may then proceed to step 620.

In step 620, the gNB 111, upon receiving the indication, may send an RRC reconfiguration message to the remote UE 121 to configure Uu and SL RLC channel configurations for the indirect path 151. In an embodiment, the RRC reconfiguration message may be sent via direct path 141 or indirect path 151. The signaling process 600 may then proceed to step 630.

In step 630, after the Uu and SL links are configured, the remote UE 121 may reply to the gNB 111 with an RRC reconfiguration complete message in response to the RRC reconfiguration message.

Fig. 6A is a flowchart of an exemplary method 600A for a remote UE that has established a direct path to add a second path (e.g., an indirect path), in accordance with some embodiments of the present disclosure. Method 600A may correspond to signaling procedures 500 and 600. In various embodiments, some of the steps of the illustrated method 600A may be performed simultaneously or in a different order than illustrated, may be replaced by other method steps, or may be omitted. Additional method steps may also be performed as desired. Aspects of the method 600A may be implemented by a wireless device, such as the remote UE 121 shown in and described with reference to the previous figures. In an embodiment, the remote UE 121 has a first path to the network (e.g., the gNB 111), and the method 600A may add to the second path of the gNB 111 for the remote UE 121. Method 600A may include steps 610A and 620A.

In step 610A, the remote UE121 receives a first RRC message from the network to add the second path. In step 620A, the remote UE121 configures the second path based on the first RRC message.

In an embodiment, the first path may be an indirect path of the remote UE121 to the network via a relay UE (e.g., relay UE 131), the second path may be a direct path of the remote UE121 to the network, and the remote UE121 and the relay UE 131 may have a serving cell belonging to the network. In an embodiment, the remote UE121 may send a measurement report to the network when a measurement event occurs. For example, the measurement event may occur when the serving cell of relay UE 131 is better than a first threshold and the serving cell of remote UE121 becomes better than a second threshold. In an embodiment, the remote UE121 may configure the second path by performing a cell (re) selection procedure based on the first RRC message to evaluate a candidate serving cell for adding the direct path, and then set the candidate serving cell as a primary cell (PCell) of the remote UE 121. In another embodiment, the remote UE121 may configure the second path by performing a secondary cell (SCell) addition procedure based on the first RRC message to add the serving cell of the remote UE as a direct path of the remote UE.

In an embodiment, the first path may be a direct path of the remote UE 121 to the network, the second path may be an indirect path of the remote UE 121 to the network via the relay UE 131, and the remote UE 121 and the relay UE 131 may have a serving cell belonging to the network. In an embodiment, the remote UE 121 may send a measurement report to the network when a measurement event occurs. For example, a measurement event may occur when the serving cell of remote UE 121 is better than the first threshold and the serving cell of relay UE 131 becomes better than the second threshold. In an embodiment, the remote UE 121 may configure the second path by performing a relay selection procedure based on the first RRC message to evaluate candidate relay UEs for adding the indirect path, and then set the candidate relay UEs as relay UEs in the indirect path of the remote UE. In another embodiment, the remote UE 121 may configure the second path based on the first RRC message by performing a cell addition procedure to add the serving cell of the relay UE as an indirect path of the remote UE. For example, the remote UE 121 may send a report to the network when updating the list of candidate relay UEs meeting the criteria for adding an indirect path. For example, the report may be sent via a ueassistance information message or a sidinkueinformation message. In an embodiment, the remote UE 121 may receive a second RRC message to configure the indirect path.

Fig. 7 illustrates an exemplary signaling process 700 for a remote UE that has established an indirect path to add a second path (e.g., a direct path) in accordance with some embodiments of the present disclosure. In an embodiment, the candidate gNB of the remote UE in the direct path is different from the gNB of the selected relay UE in the established indirect path, as shown in fig. 2. The signaling procedure 700 may reuse procedures for NRDC Secondary Cell Group (SCG) addition (e.g., DC signaling for SCG addition), the only difference being that the remote UE 221 and its primary cell group (MCG) gNB 211 may communicate with each other via SL relay.

Fig. 8 illustrates an exemplary signaling process 800 for a remote UE that has established a direct path to add a second path (e.g., an indirect path) in accordance with some embodiments of the present disclosure. In an embodiment, the candidate cell of the remote UE in the indirect path is the same as the serving cell of the remote UE in the established direct path, as shown in fig. 1. In an embodiment, the signaling procedure 800 is initiated by the remote UE 121. For example, the remote UE 121 may initiate the second path addition procedure by sending a request message. In an embodiment, when the remote UE 121 is configured to enable multipath and qualify the candidate relay (as configured by the network), the remote UE 121 may send a request message to the gNB 111 via relay forwarding to add the second path in step 810. In an embodiment, the request message may extend an existing rrcsetup request message or create a new RRC message to indicate a request to add the second path. In another embodiment, the request message may contain one or a list of suitable relay UEs meeting one or more Access Stratum (AS) criteria. For example, the AS criteria may apply conventional criteria for R17 SL relay (e.g., SL RSRP threshold), serving cell identification for the appropriate relay UE, or other criteria related to relay UE capability or relay Uu link conditions. In response, in step 820, the gNB 111 may reply with a message (e.g., agree or decline). In an embodiment, the response message may extend the existing RRCSetup/RRCReject message or apply a new RRC message. In another embodiment, if the network is provided with a list of multiple relay UEs, the network may select one of the multiple relay UEs for the remote UE 121.

Fig. 9 illustrates an exemplary signaling process 900 for a remote UE that has established a direct path to add a second path (e.g., an indirect path) in accordance with some embodiments of the present disclosure. In an embodiment, the candidate cell of the remote UE in the indirect path is the same as the serving cell of the remote UE in the established direct path, as shown in fig. 1. In an embodiment, in step 910, the remote UE 121 in the signaling procedure 900 may autonomously add an indirect path by sending an RRC message as a notification to the gNB 111 via a relay. Upon receiving the RRC message, the gNB 111 knows that the remote UE 121 wishes to apply an acknowledgement to construct the second path. Then, in step 920, the gNB 111 may reconfigure the indirect path per hop UL/SL RLC channel and one or more end-to-end bearers.

Fig. 10 illustrates an exemplary signaling process 1000 for a remote UE that has established a direct path to add a second path (e.g., an indirect path) in accordance with some embodiments of the present disclosure. In an embodiment, the serving gNB of the candidate relay UE in the indirect path is different from the gNB of the remote UE in the established direct path, as shown in fig. 2. The signaling procedure 1000 may reuse procedures for NR DC SCG addition (e.g., DC signaling for SCG addition).

In an embodiment, the relay UE and the remote UE may select different serving cells. In another embodiment, the serving cell/gNB/TRP may support only multipath configuration, where the remote UE and the relay UE may be linked to the same gNB or serving cell.

In an embodiment, if the remote UE already has a direct path and its PCell does not support inter-gNB multipath, the remote UE may exclude those candidate relay UEs connected to different gnbs.

In an embodiment, if the remote UE already has an indirect path and the PCell of the relay UE does not support inter-gNB multipath, the remote UE does not consider an NR cell different from the NR cell of the relay UE as a candidate cell.

In an embodiment, when the PCell of the remote UE does not support inter-gmb multipath, the remote UE may need to change its relay UE if the relay UE changes its serving cell. For example, if a relay UE performs a handover and thus links to a different gNB than a remote UE, the remote UE may need to change its serving cell (e.g., handover to maintain an indirect path) or change its relay (e.g., discard the indirect path and perform relay reselection, search for candidate relays that link to the same gNB as the remote UE).

Multipath: removing the second path

For inter-gNB multipath, e.g., one path on the MCG and the other on the SCG, the existing 3GPP R17 mechanism can be applied to cancel the indirect path because the two paths belong to different RRC connections and can be handled separately.

For multipaths within the gNB, both paths share the same RRC connection. The UE may then report the status of the second (to be removed) path using the existing (first) path, if desired.

In embodiments, the indirect path of the remote UE or the selected relay UE may become unavailable (e.g., a SL radio link failure occurs, SL-RSRP is below a threshold, the upper layer indicates not to use the currently selected relay, the upper layer requests to release the PC5-RRC connection, or the AS layer releases the PC5-RRC connection with the currently selected U2N relay UE). In this case, the remote UE may report to the gNB via the Uu link (direct path). For example, when SL (indirect path) is not available, a sidelinkiindicated message may be used to carry information. The remote UE may report the reason/reason for the release of the indirect path. Upon receiving the notification, the gNB will reconfigure the remote UE, e.g., deactivate SL configuration for indirect paths towards the unused relay, and may trigger procedures for PDCP re-establishment or PDCP restoration. The non-received PDCP packets may be retransmitted in the UL and DL directions via a direct path. The remote UE configured with the multipath feature does not need to perform an RRC reestablishment procedure after breaking the indirect path (because the direct link is still working properly), but may trigger a relay (re) selection procedure to search for an appropriate relay UE for the second path addition.

In an embodiment, the gNB may trigger the UE to cancel the path. For example, in the case of a UE with few transmitted traffic flows, the gNB may want the UE to maintain a single indirect path to save power. To trigger the second path removal, the gNB may send an RRC message (via direct or indirect path) to the remote UE to indicate which path to remove and instruct the remote UE to reconfigure/release the corresponding AS configuration. For example, to deactivate the indirect path, the remote UE may be configured to deactivate the SL RLC configuration towards the indirect path. For example, to deactivate the direct path, the remote UE may be instructed to empty all Physical Uplink Control Channel (PUCCH)/Sounding Reference Signal (SRS) configurations for the deactivated serving cell and reset the Uu MAC entity. The RRC release message may be reused if the two (direct and indirect) paths are considered to be different RRC connections. Otherwise, the network may extend the existing RRC message (e.g., RRC release or RRC reconfiguration) to remove the path without changing the RRC state of the UE or triggering the RRC reestablishment procedure.

New metering event for multipath

In 3gpp r17 SL relay, there are multiple measurement events defined for the UE to trigger event-based measurement reporting. In particular, measurement events X1, X2, Y1, and Y2 are specified for R17 SL relay. The measurement event X1 occurs when the serving L2U2N relay UE becomes worse than the first threshold and the NR cell becomes better than the second threshold. The measurement event X2 occurs when the serving L2U2N relay UE becomes worse than a threshold. The measurement event Y1 occurs when the PCell becomes worse than the first threshold and the candidate L2U2N relay UE becomes better than the second threshold. The measurement event Y2 occurs when the candidate L2U2N relay UE becomes better than the threshold.

To support multi-path configuration, multiple new measurement events may be specified so that the network may have knowledge about the cell/relay link quality, which may be used to determine whether to add or remove the second path.

In an embodiment, the new measurement events M1, M2, M3 and M4 for the multipath configuration have similar definitions as the measurement events X1, X2, Y1 and Y2, respectively, and the threshold may be in dB for RSRQ or SINR or dBm for RSRP, for example.

In an embodiment, a measurement event M1 triggering measurement report transmission for multipath occurs when a serving L2U 2N relay UE becomes better than a first threshold and an NR cell becomes better than a second threshold, as disclosed in signaling procedure 500. The measurement event M1 is intended to inform the network of the availability of the addition of the second path (direct path).

In an embodiment, as disclosed in signaling procedure 600, a measurement event M2 triggering the transmission of a measurement report for multipath occurs when the PCell becomes better than a first threshold and the candidate L2U 2N relay UE becomes better than a second threshold. The measurement event M2 is intended to inform the network of the availability of the addition of the second path (indirect path).

In an embodiment, a measurement event M3 triggering measurement report transmission for multipath occurs when the serving L2U 2N relay UE becomes better than a first threshold and the PCell becomes worse than a second threshold. The measurement event M3 is intended to inform the network of the availability to remove the second path (direct path). For example, as shown in fig. 1, when measurement event M3 occurs, remote UE 121 may send a measurement report dedicated to multipath to gNB 111, allowing gNB 111 to decide whether to drop the direct path, and gNB 111 may then send an RRC reconfiguration message to remote UE 121 to trigger the drop of the direct path.

In an embodiment, a measurement event M4 triggering measurement report transmission for multipath occurs when the serving L2U 2N relay UE becomes worse than a first threshold and the PCell becomes better than a second threshold. The measurement event M4 is intended to inform the network about the availability of the removal of the second path (indirect path). For example, as shown in fig. 1, when measurement event M4 occurs, remote UE 121 may send a measurement report dedicated to multipath to gNB 111, allowing gNB 111 to decide whether to remove the indirect path, and gNB 111 may then send an RRC reconfiguration message to remote UE 121 to trigger removal of the indirect path.

In an embodiment, if the remote UE has configured the maximum number of configurable paths and all configured paths work well, e.g., the measured amount of each configured path is better than a threshold, the remote UE configured with multipath is not requested to measure potential candidate serving cells or candidate relay UEs.

Fig. 11 is a flowchart of an exemplary method 1100 of a remote UE having a first path to a network and a second path to the network, according to some embodiments of the present disclosure. The method 1100 involves removing the second path by determining measurement events M3 and M4. In various embodiments, some of the steps of the illustrated method 1100 may be performed simultaneously or in a different order than illustrated, may be replaced by other method steps, or may be omitted. Additional method steps may also be performed as desired. Aspects of the method 1100 may be implemented by a wireless apparatus, such as the remote UE 121 shown in and described with reference to the previous figures. In an embodiment, the remote UE 121 has a first path and a second path to the network (e.g., the gNB 111), and the method 1100 may remove the second path for the remote UE 121 from the gNB 111. Method 1100 may include steps 1110 and 1120.

In step 1110, the remote UE 121 receives an RRC message from the network that removes the second path. In step 1120, the remote UE 121 configures a second path based on the RRC message.

In an embodiment, the first path may be an indirect path of the remote UE 121 to the network via a relay UE (e.g., relay UE 131), the second path may be a direct path of the remote UE 121 to the network, and the remote UE 121 and the relay UE 131 may have a serving cell belonging to the network. In an embodiment, the remote UE 121 may send a measurement report to the network when a measurement event occurs. For example, a measurement event may occur when the serving cell of relay UE 131 is better than the first threshold and the serving cell of remote UE 121 becomes worse than the second threshold.

In an embodiment, the first path may be a direct path of the remote UE 121 to the network, the second path may be an indirect path of the remote UE 121 to the network via the relay UE 131, and the remote UE 121 and the relay UE 131 may have a serving cell belonging to the network. In an embodiment, the remote UE 121 may send a measurement report to the network when a measurement event occurs. For example, a measurement event may occur when the serving cell of relay UE 131 is better than the first threshold and the serving cell of remote UE 121 becomes worse than the second threshold.

Fig. 12 is a functional block diagram of an apparatus 1200 (e.g., a UE). For example, apparatus 1200 may include circuitry, such as memory circuitry 1210 and processing circuitry 1220, configured to perform methods, such as methods 600A and 1100. In an embodiment, the apparatus may have a first path to a network and the method is a second path for the apparatus to add to the network, and the method may include receiving a first RRC message from the network to add the second path and configuring the second path based on the first RRC message.

In an embodiment, the first path is an indirect path of the device to the network via another device, the second path is a direct path of the device to the network, and the device and the other device have a serving cell belonging to the network.

In an embodiment, the method may further comprise sending a measurement report to the network when a measurement event occurs. For example, a measurement event may occur when a serving cell of another device is better than a first threshold and the serving cell of the device becomes better than a second threshold. In an embodiment, configuring the second path based on the first RRC message may include: performing a cell (re) selection procedure to evaluate candidate serving cells for adding direct paths; the candidate serving cell is set as the primary cell PCell of the device. In another embodiment, configuring the second path based on the first RRC message may include performing a secondary cell (SCell) addition procedure to add a serving cell of the apparatus as a direct path of the apparatus.

In an embodiment, the first path may be a direct path of the device to the network, the second path may be an indirect path of the device to the network via another device, and the device and the other device may have a serving cell belonging to the network. In an embodiment, the method may further comprise sending a measurement report to the network when a measurement event occurs. For example, a measurement event may occur when a serving cell of a device is better than a first threshold and a serving cell of another device becomes better than a second threshold. In an embodiment, configuring the second path based on the first RRC message may include: performing a relay selection procedure, evaluating candidate relay UEs for adding an indirect path; and setting the candidate relay UE as another device in the indirect path of the device. In another embodiment, configuring the second path based on the first RRC message may include performing a cell addition procedure to add a serving cell of another apparatus as an indirect path of the apparatus.

In an embodiment, performing the cell addition procedure may include sending a report to the network when the list of candidate relay UEs meeting the criteria for adding the indirect path is updated. For example, the report may be sent via a ueassistance information message or a sidinkueinformation message. In an embodiment, the method may further include receiving a second RRC message to configure the indirect path.

In an embodiment, the method may further include receiving an RRC message from the network to remove the second path, and removing the second path based on the RRC message. In an embodiment, the first path is an indirect path of the device to the network via another device, the second path is a direct path of the device to the network, and the device and the other device have a serving cell belonging to the network. In an embodiment, the method may further comprise sending a measurement report to the network when a measurement event occurs. In an embodiment, the measurement event occurs when the serving cell of the other device is better than the first threshold and the serving cell of the device becomes worse than the second threshold. In an embodiment, the first path is a direct path of the device to the network, the second path is an indirect path of the device to the network via another device, and the device and the other device have a serving cell belonging to the network. In an embodiment, the method may further comprise sending a measurement report to the network when a measurement event occurs, wherein the measurement event occurs when the serving cell of the other apparatus is better than the first threshold and the serving cell of the apparatus becomes worse than the second threshold.

The processes and functions described herein may be implemented as a computer program that, when executed by one or more processors, may cause the one or more processors to perform the corresponding processes and functions. A computer program may be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware. The computer program may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems. For example, a computer program may be obtained and loaded into a device, including by a physical medium or a distributed system (including, for example, from a server connected to the internet).

The computer program may be accessed from a computer readable medium providing program instructions for use by or in connection with a computer or any instruction execution system. A computer-readable medium may include any means that stores, communicates, propagates, or transports the computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer readable medium can be a magnetic, optical, electrical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. The computer-readable medium may include computer-readable non-transitory storage media such as semiconductor or solid state memory, magnetic tape, removable computer diskette, random Access Memory (RAM), read-only memory (ROM), magnetic and optical disk and the like. Computer-readable non-transitory storage media may include all types of computer-readable media, including magnetic storage media, optical storage media, flash memory media, and solid-state storage media.

Although aspects of the present disclosure have been described in connection with specific embodiments thereof, which are set forth as examples, alternatives, modifications, and variations may be made to the examples. Accordingly, the embodiments set forth herein are intended to be illustrative, not limiting. Changes may be made without departing from the scope of the claims set forth below.

Claims (22)

1. A method for a first user equipment, UE, having a first path to a network to be added to a second path of the network, the method comprising the steps of:

receiving, at the first UE, a first radio resource control, RRC, message from the network to add the second path; and

the second path is configured by the first UE based on the first RRC message.

2. The method of claim 1, wherein the first path is an indirect path of the first UE to the network via a second UE, the second path is a direct path of the first UE to the network, and the first UE and the second UE have serving cells belonging to the network.

3. The method of claim 2, the method further comprising:

when a measurement event occurs, the first UE sends a measurement report to the network.

4. The method of claim 3, wherein the measurement event occurs when a serving cell of the second UE is better than a first threshold and a serving cell of the first UE becomes better than a second threshold.

5. The method of claim 2, wherein configuring, by the first UE, the second path based on the first RRC message comprises:

Performing a cell (re) selection procedure to evaluate candidate serving cells for adding the direct path; and

the candidate serving cell is set as a primary cell (PCell) of the first UE.

6. The method of claim 2, wherein configuring, by the first UE, the second path based on the first RRC message comprises:

a secondary cell (SCell) addition procedure is performed to add the serving cell of the first UE as a direct path for the first UE.

7. The method of claim 1, wherein the first path is a direct path of the first UE to the network, the second path is an indirect path of the first UE to the network via a second UE, and the first UE and the second UE have serving cells belonging to the network.

8. The method of claim 7, the method further comprising:

when a measurement event occurs, the first UE sends a measurement report to the network.

9. The method of claim 8, wherein the measurement event occurs when a serving cell of the first UE is better than a first threshold and a serving cell of the second UE becomes better than a second threshold.

10. The method of claim 7, wherein configuring, by the first UE, the second path based on the first RRC message comprises:

performing a relay selection procedure to evaluate candidate relay UEs for adding the indirect path; and

the candidate relay UE is set as a second UE in an indirect path of the first UE.

11. The method of claim 7, wherein configuring, by the first UE, the second path based on the first RRC message comprises:

a cell addition procedure is performed to add a serving cell of the second UE as the indirect path for the first UE.

12. The method of claim 11, wherein performing the cell addition procedure comprises: a report is sent by the first UE to the network when a list of candidate relay UEs meeting criteria for adding the indirect path is updated.

13. The method of claim 12, wherein the report is sent via a ueassistance information message or a sidinkueinformation message.

14. The method of claim 13, the method further comprising: a second RRC message is received to configure the indirect path.

15. A method for a remote user equipment, UE, having a first path to a network and a second path to the network, the method comprising the steps of:

Receiving, at the first UE, a radio resource control, RRC, message from the network to remove the second path; and

the second path is removed by the first UE based on the RRC message.

16. The method of claim 15, wherein the first path is an indirect path of the first UE to the network via a second UE, the second path is a direct path of the first UE to the network, and the first UE and the second UE have serving cells belonging to the network.

17. The method of claim 16, the method further comprising:

when a measurement event occurs, the first UE sends a measurement report to the network.

18. The method of claim 17, wherein the measurement event occurs when a serving cell of the second UE is better than a first threshold and a serving cell of the first UE becomes worse than a second threshold.

19. The method of claim 15, wherein the first path is a direct path of the first UE to the network, the second path is an indirect path of the first UE to the network via a second UE, and the first UE and the second UE have serving cells belonging to the network.

20. The method of claim 19, the method further comprising:

transmitting, by the first UE, a measurement report to the network when a measurement event occurs;

wherein the measurement event occurs when the serving cell of the second UE is better than a first threshold and the serving cell of the first UE becomes worse than a second threshold.

21. An apparatus having a first path to a network, the apparatus comprising circuitry configured to perform a method for the apparatus to add to and remove from the network a second path, the method comprising the steps of:

receiving a first radio resource control, RRC, message from the network to add the second path; and

the second path is configured based on the first RRC message.

22. The apparatus of claim 21, wherein the method further comprises:

receiving a second RRC message from the network to remove the second path; and

the second path is removed based on the second RRC message.