CN117336806A

CN117336806A - Method and network node for supporting direct-to-indirect path switching between GNBs

Info

Publication number: CN117336806A
Application number: CN202310698393.7A
Authority: CN
Inventors: 潘立德
Original assignee: Asus Technology Licensing Inc
Current assignee: Asus Technology Licensing Inc
Priority date: 2022-06-30
Filing date: 2023-06-13
Publication date: 2024-01-02

Abstract

The invention provides a method and a network node for supporting direct-to-indirect path switching between GNBs. The method comprises the following steps: the first network node receives first information of candidate relay user equipments from a remote user equipment. The method further comprises the first network node sending first information of the candidate relay user equipment or second information of the candidate relay user equipment to the second network node for the second network node to select the target relay user equipment, wherein the second information of the candidate relay user equipment is derived from the first information of the candidate relay user equipment.

Description

Method and network node for supporting direct-to-indirect path switching between GNBs

Cross Reference to Related Applications

The present application claims the benefits of U.S. provisional patent application nos. 63/357,419 and 63/357,447 to 2022, 6, 30, the entire disclosures of which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates generally to wireless communication networks, and more particularly, to a method and apparatus for supporting direct-to-indirect path switching between GNBs for UE-to-NW relay communication in a wireless communication system, and more particularly, to a method and network node for supporting direct-to-indirect path switching between GNBs.

Background

With the rapid increase in demand for large amounts of data to and from mobile communication devices, conventional mobile voice communication networks evolve into networks that communicate with internet protocol (Internet Protocol, IP) data packets. This IP packet communication may provide voice over IP, multimedia, multicast, and on-demand communication services to users of mobile communication devices.

An exemplary network structure is an evolved universal terrestrial radio access network (Evolved Universal Terrestrial Radio Access Network, E-UTRAN). The E-UTRAN system may provide high data throughput for implementing the above-described IP-bearing voice and multimedia services. Currently, the 3GPP standards organization is discussing new next generation (e.g., 5G) radio technologies. Thus, changes to the current body of the 3GPP standard are currently being submitted and considered to evolve and complete the 3GPP standard.

Disclosure of Invention

Methods and apparatus for a first network node are disclosed. In one embodiment, a method includes a first network node receiving first information of a candidate relay UE from a remote User Equipment (UE). The method further includes the first network node sending first information of the candidate relay UE or second information of the candidate relay UE to the second network node for the second network node to select the target relay UE, wherein the second information of the candidate relay UE is derived from the first information of the candidate relay UE.

Drawings

Fig. 1 illustrates a diagram of a wireless communication system according to an example embodiment;

fig. 2 is a block diagram of a transmitter system (also referred to as an access network) and a receiver system (also referred to as a user equipment or UE) according to an example embodiment;

FIG. 3 is a functional block diagram of a communication system according to an exemplary embodiment;

FIG. 4 is a functional block diagram of the program code of FIG. 3 according to one exemplary embodiment;

FIG. 5 is a reproduction of FIG. 6.3.2.3.2-1 of 3GPP TS 23.304V17.2.1;

FIG. 6 is a reproduction of FIG. 6.4.3.1-1 of 3GPP TS 23.304V17.2.1;

FIG. 7 is a reproduction of table 10.2.1.8 of 3GPP TS 24.554V17.1.0;

fig. 8 is a reproduction of fig. 11.2.14.1 of 3GPP TS 24.554V17.1.0;

fig. 9 is a reproduction of table 11.2.14.1 of 3GPP TS 24.554V17.1.0;

FIG. 10 is a reproduction of FIG. 4.5.1.1-3 of 3GPP TS 38.836V17.0.0;

FIG. 11 is a reproduction of FIG. 4.5.1.1-4 of 3GPP TS 38.836V17.0.0;

fig. 12 is a reproduction of fig. 5.3.3.1-1 of 3GPP TS 38.331V17.0.0;

FIG. 13 is a reproduction of FIG. 5.3.7.1-1 of 3GPP TS 38.331V17.0.0;

FIG. 14 is a reproduction of FIG. 5.5.5.1-1 of 3GPP R2-2206823;

FIG. 15 is a reproduction of FIG. 5.8.3.1-1 of 3GPP R2-2206823;

FIG. 16 is a reproduction of FIG. 5.8.9.1.1-1 of 3GPP R2-2206823;

FIG. 17 is a reproduction of FIG. 9.2.3.1-1 of 3GPP TS 38.300V17.0.0;

FIG. 18 is a reproduction of FIG. 16.12.5.1-1 of 3GPP R2-2206232;

FIG. 19 is a reproduction of FIG. 16.12.6.2-1 of 3GPP R2-2206232;

FIG. 20 is a reproduction of FIG. 6.2.2-1 of 3GPP TS 38.351V17.0.0;

FIG. 21 is a reproduction of FIG. 6.23.2.2-1 of 3GPP TS 23.700-33V0.3.0;

FIG. 22 is a reproduction of FIG. 6.23.2.4-1 of 3GPP TS 23.700-33V0.3.0;

FIG. 23 illustrates a flow of steps for direct to indirect communication path switching between gNBs in accordance with one illustrative embodiment;

FIG. 24 is a flowchart in accordance with an exemplary embodiment;

FIG. 25 is a flowchart in accordance with an exemplary embodiment;

FIG. 26 is a flowchart in accordance with an exemplary embodiment;

FIG. 27 is a flowchart in accordance with an exemplary embodiment.

Detailed Description

The exemplary wireless communication systems and apparatus described below employ wireless communication systems that support broadcast services. Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be based on Code Division Multiple Access (CDMA), time Division Multiple Access (TDMA), orthogonal Frequency Division Multiple Access (OFDMA), 3GPP long term evolution (Long Term Evolution, LTE) wireless access, 3GPP long term evolution advanced (Long Term Evolution Advanced, LTE-a), 3GPP2 ultra mobile broadband (Ultra Mobile Broadband, UMB), wiMax, 3GPP New Radio (NR), or some other modulation technique.

In particular, the exemplary wireless communication systems and devices described below may be designed to support one or more standards, such as those provided by a complex referred to herein as 3GPP, denominated "third generation partnership project," including: TS 23.304V17.2.1, "proximity-based services (ProSe) (release 17) in 5G System (5 GS)"; TS 24.554V17.1.0, "proximity services (ProSe) in the 5G System (5 GS) protocol aspect; stage 3 (version 17) "; TR 38.836, v17.0.0, "study on NR side link relay; (version 17) "; TS 38.331V17.0.0, "Radio Resource Control (RRC) protocol specification (release 17)"; r2-2206823, CR for TS 38.331, "miscellaneous correction for NR SL trunking," Hua is Hai Si (Huawei, hisilicon); TS 38.300V17.0.0, "NR and NG-RAN general description; stage 2 (version 17) "; r2-2206232, CR for TS 38.300, "correction for phase 2 of side link relaying", concurrent science (MediaTek Inc.); TS 38.351v17.0.0, "side link Relay Adaptation protocol (SRAP) Specification (version 17)"; TR 23.700-33v0.3.0, "system enhanced study of proximity-based services (ProSe) in 5G system (5 GS); stage 2 (version 18) "; and RP-221262, "modified WID with NR side link relay enhancement," LG Electronics. The standards and documents listed above are hereby expressly incorporated by reference in their entirety.

Fig. 1 illustrates a multiple access wireless communication system according to one embodiment of the present invention. The access network 100 (AN) includes multiple antenna groups, one including 104 and 106, another including 108 and 110, and yet another including 112 and 114. In fig. 1, only two antennas are shown for each antenna group, but more or fewer antennas may be utilized for each antenna group. An Access terminal 116 (AT) is in communication with antennas 112 and 114, where antennas 112 and 114 transmit information to Access terminal 116 over forward link 120 and receive information from Access terminal 116 over reverse link 118. An Access Terminal (AT) 122 is in communication with antennas 106 and 108, where antennas 106 and 108 transmit information to Access Terminal (AT) 122 over a forward link 126 and receive information from Access Terminal (AT) 122 over a reverse link 124. In an FDD system, communication links 118, 120, 124 and 126 may use different frequency for communication. For example, forward link 120 may use a different frequency than that used by reverse link 118.

The antennas of each group and/or the area in which they are designed to communicate are often referred to as a sector of the access network. In an embodiment, antenna groups each are designed to communicate to access terminals in a sector of the areas covered by access network 100.

In communication over forward links 120 and 126, the transmit antennas of access network 100 may utilize beamforming in order to improve signal-to-noise ratio of forward links for the different access terminals 116 and 122. And, the access network using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than an access network transmitting through a single antenna to all its access terminals.

AN Access Network (AN) may be a fixed station or base station used for communicating with the terminals and may also be referred to as AN access point, a node B, a base station, AN enhanced base station, AN evolved node B (eNB), a network node, a network, or some other terminology. An Access Terminal (AT) may also be referred to as a User Equipment (UE), a wireless communication device, a terminal, an access terminal, or some other terminology.

Fig. 2 is a simplified block diagram of an embodiment of a transmitter system 210 (also referred to as an access network) and a receiver system 250 (also referred to as an Access Terminal (AT) or User Equipment (UE)) in a MIMO system 200. At the transmitter system 210, traffic data for a number of data streams is provided from a data source 212 to a Transmit (TX) data processor 214.

In one embodiment, each data stream is transmitted through a respective transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QPSK, M-PSK or M-QAM) selected for that data stream to provide modulation symbols. Instructions executed by processor 230 may determine the data rate, coding, and modulation for each data stream.

The modulation symbols for all data streams are then provided to a TX MIMO processor 220, which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor 220 then applies N _T Providing the modulated symbol streams to N _T Transmitters (TMTR) 222a through 222t. In certain embodiments, TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Then respectively from N _T The antennas 224a through 224t transmit N from the transmitters 222a through 222t _T Each modulated signalNumber (x).

At the receiver system 250, the signal is represented by N _R Each antenna 252 a-252 r receives the transmitted modulated signals and provides the signals received from each antenna 252 to a respective receiver (RCVR) 254 a-254 r. Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding "received" symbol stream.

RX data processor 260 then proceeds to process the data from N based on a particular receiver _R The N is received and processed by a plurality of receivers 254 _R Providing N by receiving symbol streams _T The "detected" symbol streams. RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor 260 is complementary to that performed by TX MIMO processor 220 and TX data processor 214 at transmitter system 210.

The processor 270 periodically determines which pre-coding matrix to use (discussed below). Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.

The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, modulated by a modulator 280, conditioned by transmitters 254a through 254r, and transmitted back to transmitter system 210.

At transmitter system 210, the modulated signals from receiver system 250 are received by antennas 224, conditioned by receivers 222, demodulated by a demodulator 240, and processed by a RX data processor 242 to extract the reverse link message transmitted by receiver system 250. Processor 230 then determines which pre-coding matrix to use to determine the beamforming weights and then processes the extracted message.

Turning to fig. 3, this figure shows an alternative simplified functional block diagram of a communication device according to one embodiment of the present invention. As shown in fig. 3, a communication device 300 in a wireless communication system may be utilized for implementing UEs (or ATs) 116 and 122 in fig. 1 or base station (or AN) 100 in fig. 1, and the wireless communication system is preferably AN NR system. The communication device 300 may include an input device 302, an output device 304, a control circuit 306, a central processing unit (central processing unit, CPU) 308, a memory 310, program code 312, and a transceiver 314. The control circuit 306 executes the program code 312 in the memory 310 via the CPU 308, thereby controlling the operation of the communication device 300. The communication device 300 may receive signals input by a user through an input device 302 (e.g., a keyboard or keypad) and may output images and sounds through an output device 304 (e.g., a monitor or speaker). The transceiver 314 is used to receive and transmit wireless signals, pass the received signals to the control circuit 306, and wirelessly output signals generated by the control circuit 306. The AN 100 of fig. 1 may also be implemented with a communication device 300 in a wireless communication system.

Fig. 4 is a simplified block diagram of the program code 312 shown in fig. 3 according to one embodiment of the invention. In this embodiment, program code 312 includes an application layer 400, a layer 3 portion 402, and a layer 2 portion 404, and is coupled to a layer 1 portion 406. Layer 3 portion 402 typically performs radio resource control. Layer 2 portion 404 typically performs link control. Layer 1 portion 406 typically performs physical connections.

3GPP TS 23.304 introduces some procedures related to unicast link communication as follows:

5.8.2 identifier for 5G ProSe direct communication

5.8.2.1 general rule

Each UE has one or more layer 2 IDs for 5G ProSe direct communication over PC5 reference points, consisting of:

-source layer 2ID; and

-destination layer 2ID.

The source and destination layer 2 IDs are contained in layer 2 frames sent on the layer 2 link of the PC5 reference point identifying the layer 2 source and destination of these frames. The source layer 2ID is always self-assigned by the UE initiating the corresponding layer 2 frame.

The selection of source and destination layer 2 IDs by the UE depends on the communication mode of 5G ProSe direct communication over the PC5 reference point for this layer 2 link as described in clauses 5.8.2.2, 5.8.2.3 and 5.8.2.4. The source layer 2ID may be different between different communication modes.

[…]

5.8.2.4 identifier for unicast mode 5G ProSe direct communication

For unicast mode 5G ProSe direct communication through PC5 reference point, the destination layer 2ID used depends on the communicating peer. The layer 2ID of the communicating peer identified by the application layer ID of the peer may be discovered during the establishment of the PC5 unicast link or directly communicated via a previous ProSe, e.g. known to the UE to an existing or previous unicast link to the same application layer ID or obtained from a 5G ProSe direct discovery procedure. The initial signaling for establishing the PC5 unicast link may use a known layer 2ID of the communication peer, or a preset destination layer 2ID associated with a ProSe service (i.e., proSe identifier) configured for PC5 unicast link establishment, as specified in clause 5.1.3.1. As specified in clause 6.4.3, during the PC5 unicast link setup procedure, the layer 2ID is exchanged and applied for future communication between two UEs.

Since ProSe application layer does not use layer 2ID, ue maintains mapping between application layer ID and source layer 2ID for PC5 unicast link. This allows the source layer 2ID to be changed without interrupting ProSe applications.

When the application layer ID changes, the source layer 2ID of the PC5 unicast link should change if the link is used for 5G ProSe communication with the changed application layer ID.

Updating the new identifier of the source UE to the peer UE for the established unicast link may cause the peer UE to change its layer 2ID and optionally IP address/prefix (if IP communication is generally used as defined in clause 6.4.3.2) based on the privacy configuration as specified in clause 5.1.3.1.

[…]

6.1.1.2.2PC5 Signaling protocol

The PC5 signaling protocol stack specified in clause 6.1.2 of TS 23.287[2] is used. The protocols for control plane signaling of the PC5 reference point over the secure layer 2 link are specified in clauses 6.4.3, 6.5.1 and 6.5.2.

[…]

6.3.2.3 5G ProSe UE-to-network relay discovery

6.3.2.3.1 general rule

The 5G ProSe UE-to-network relay discovery applies to both 5G ProSe layer 3 and layer 2 UE-to-network relay discovery for public safety use and commercial services. To perform 5G ProSe UE-to-network relay discovery, 5G ProSe remote UEs and 5G ProSe UE-to-network relays are preconfigured or provision the relevant information as described in clause 5.1.

In 5G ProSe UE-to-network relay discovery, the UE uses preconfigured or provisioned information for the relay discovery procedure as defined in clause 5.1.4.1.

A Relay Service Code (RSC) is used for 5G ProSe UE-to-network relay discovery to indicate connectivity services provided by the 5G ProSe UE-to-network relay to the 5G ProSe remote UE. The PSC is configured on a 5G ProSe UE-to-network relay and a 5G ProSe remote UE as defined in clause 5.1.4. The 5G ProSe UE-to-network relay and 5G ProSe remote UE know whether the RSC is providing a 5G ProSe layer 2 or layer 3 UE-to-network relay service based on the policy as specified in clause 5.1.4. The 5G ProSe UE-to-network relay supporting multiple RSCs may advertise RSCs using multiple discovery messages, one RSC per discovery message.

Additional information not directly used for discovery may also be advertised using a PC5-D protocol stack in a single or separate discovery message of the type "relay discovery additional information" as defined in clause 5.8.3.1.

6.3.2.3.2 procedure for 5G ProSe UE-to-network relay discovery using model A

Depicted in fig. 6.3.2.3.2-1 is a procedure for 5G ProSe UE-to-network discovery using model a.

Fig. 6.3.2.3.2-1 entitled "5G ProSe UE to network relay discovery using model a" of 3GPP TS 23.304V17.2.1 is reproduced as fig. 5]

The 1.5G ProSe UE-to-network relay sends a UE-to-network relay discovery notification message. The UE-to-network relay discovery notification message contains the type of discovery message, notifier information, and RSC and is sent using the source tier 2ID and destination tier 2ID as described in clause 5.8.3.

For 5G ProSe layer 3 UE-to-network relay, when the S-nsai associated with the RSC belongs to the allowed nsai for UE-to-network relay, the 5G ProSe layer 3 UE-to-network relay should contain only the RSC in the UE-to-network relay discovery notification.

The 5G ProSe remote UE (1 to 3) determines a destination layer 2ID for signaling reception. The UE is configured with the destination layer 2ID as specified in clause 5.1.4.1.

The 5G ProSe remote UE (1 to 3) listens for a notification message with a 5G ProSe UE to network RSC corresponding to the desired service.

Optionally, the 5G ProSe UE-to-network relay may also send a relay discovery additional information message as defined in clause 6.5.1.3. The parameters contained in this message, source layer 2ID and destination layer 2ID for sending and receiving messages are described in clause 5.8.3.

The 5G ProSe remote UE selects a 5G ProSe UE to network relay based on the information received in step 1.

Note that: the access stratum information for 5G ProSe UE-to-network relay selection is specified in the RAN specifications.

[…]

6.4.3 unicast mode 5G ProSe direct communication

6.4.3.1 layer 2 link establishment through PC5 reference point

In order to perform unicast mode of ProSe direct communication on PC5 reference point, UE is configured with related information as described in clause 5.1.3.

Fig. 6.4.3.1-1 shows a layer 2 link setup procedure for ProSe direct communication in unicast mode through PC5 reference point.

[3GPP TS 23.304V17.2.1, FIG. 6.4.3.1-1 entitled "layer 2 Link setup procedure" is reproduced as FIG. 6]

1. As specified in clause 5.8.2.4, the UE determines the destination layer 2ID for signaling reception for PC5 unicast link establishment.

The ProSe application layer in ue-1 provides application information for PC5 unicast communication. The application information includes ProSe service information, an application layer ID of the UE. The application information may include an application layer ID of the target UE.

The ProSe application layer in UE-1 may provide ProSe application requirements for this unicast communication. As specified in clause 5.6.1, UE-1 determines PC5 QoS parameters and PFI.

If the UE-1 decides to reuse the existing PC5 unicast link as specified in clause 5.3.4, the UE triggers the layer 2 link modification procedure as specified in clause 6.4.3.4.

Ue-1 sends a direct communication request message to initiate a unicast layer 2 link setup procedure. The direct communication request message includes:

-source user information: the application layer ID of the UE (i.e., the application layer ID of UE-1) is initiated.

-if in step 2 the ProSe application layer provides the application layer ID of the target UE, the following information is contained:

-target user information: the application layer ID of the target UE (i.e., the application layer ID of UE-2).

ProSe service information: information about ProSe identifier requesting layer 2 link setup.

Security information: information for establishing security.

Note 1: the security information and the necessary protection for the source and target user information are defined by the SA WG 3.

The source layer 2ID and the destination layer 2ID for transmitting the direct communication request message are determined as specified in clauses 5.8.2.1 and 5.8.2.4. The destination layer 2ID may be a broadcast or unicast layer 2ID. When using the unicast layer 2ID, the target user information should be included in the direct communication request message.

The UE-1 transmits a direct communication request message via the PC5 broadcast or unicast using the source layer 2ID and the destination layer 2 ID.

4. The security of UE-1 is established as follows:

4a. If the target user information is included in the direct communication request message, the target UE (i.e., UE-2) responds by establishing security with UE-1.

4b. If the target user information is not included in the direct communication request message, the UE interested in ProSe service notified through PC5 unicast link usage with UE-1 responds by establishing security with UE-1.

And (2) injection: signaling for security procedures is defined by the SA WG 3.

When security protection is enabled, UE-1 sends the following information to the target UE:

-if IP communication is used:

-IP address configuration: for IP communications, this link requires an IP address configuration, and it indicates one of the following values:

- "DHCPv4 server", i.e. acting as DHCPv4 server if only the IPv4 address allocation mechanism is supported by the initiating UE; or (b)

-an "IPv6 router", which acts as an IPv6 router if the initiating UE only supports the IPv6 address allocation mechanism; or (b)

- "DHCPv4 server and IPv6 router", if both IPv4 and IPv6 address allocation mechanisms are supported by the initiating UE; or (b)

"not supporting address assignment", if neither IPv4 nor IPv6 address assignment mechanisms are supported by the initiating UE.

-link local IPv6 address: if UE-1 does not support the IPv6 IP address assignment mechanism, i.e., IP address configuration indicates "does not support address assignment," then link local IPv6 addresses are formed locally based on RFC 4862[17 ].

QoS information: information about one or more PC5QoS flows. For each PC5QoS flow, the PFI and corresponding PC5QoS parameters (i.e., PQI and, conditionally, other parameters such as MFBR/GFBR) and associated ProSe identifier.

-optional PC5QoS rules.

The source layer 2ID for the security setup procedure is determined as specified in clauses 5.8.2.1 and 5.8.2.4. The destination layer 2ID is set to the source layer 2ID of the received direct communication request message.

Upon receiving the security setup procedure message, UE-1 obtains the layer 2ID of the peer UE for future communications for signaling and data traffic for this unicast link.

5. One or more target UEs that have successfully established security with UE-1 send a direct communication accept message to UE-1:

(UE-oriented layer 2 link establishment) if the direct communication request message contains target user information, then the target UE (i.e., UE-2) responds with a direct communication accept message if the application layer ID for UE-2 matches.

(layer 2 link establishment towards ProSe service) if the target user information is not included in the direct communication request message, UEs interested in using the notified ProSe service (UE-2 and UE-4 in fig. 6.4.3.1-1) respond to the request by sending a direct communication accept message.

The direct communication accept message includes:

-source user information: an application layer ID of the UE transmitting the direct communication accept message.

QoS information: information about one or more PC5 QoS flows. For each PC5 QoS flow, the PFI requested by UE-1 and the corresponding PC5 QoS parameters (i.e., PQI and, conditionally, other parameters such as MFBR/GFBR) and optionally the associated ProSe identifier.

-optional PC5 QoS rules.

-if IP communication is used:

- "DHCPv4 server", i.e. acting as DHCPv4 server if only the IPv4 address allocation mechanism is supported by the target UE; or (b)

-an "IPv6 router", if the target UE supports only IPv6 address allocation mechanism, i.e. acts as an IPv6 router; or (b)

- "DHCPv4 server and IPv6 router", if both IPv4 and IPv6 address allocation mechanisms are supported by the target UE; or (b)

"not supporting address assignment", if neither IPv4 nor IPv6 address assignment mechanisms are supported by the target UE.

-link local IPv6 address: based on the link-local IPv6 address formed locally by RFC 4862[17], if the target UE does not support the IPv6IP address allocation mechanism, i.e., the IP address configuration indicates "does not support address allocation", and UE-1 includes the link-local IPv6 address in the direct communication request message. The target UE should contain a non-conflicting link local IPv6 address.

If two UEs (i.e., the initiating UE and the target UE) are selected to use the link-local IPv6 address, then the two UEs will deactivate the dual address detection defined in RFC 4862[17 ].

And (3) injection: when the initiating UE or the target UE indicates support for the IPv6 router, the corresponding address configuration procedure will be implemented after the layer 2 link is established and the link local IPv6 address is ignored.

The ProSe layer of the UE that establishes the PC5 unicast link passes the PC5 link identifier assigned for the unicast link and PC5 unicast link related information down to the AS layer. The information related to the PC5 unicast link contains layer 2ID information (i.e., source layer 2ID and destination layer 2 ID). This enables the AS layer to maintain PC5 link identifiers and PC5 unicast link related information.

6. ProSe data is transmitted over the established unicast link as follows:

the PC5 link identifier and PFI are provided to the AS layer along with ProSe data.

In addition, layer 2ID information (i.e., source layer 2ID and destination layer 2 ID) is optionally provided to the AS layer.

And (4) injection: layer 2ID information is provided to the AS layer by the UE implementation.

UE-1 transmits ProSe data using the source layer 2ID (i.e., layer 2ID of UE-1 for this unicast link) and the destination layer 2ID (i.e., layer 2ID of peer UE for this unicast link).

And (5) injection: the PC5 unicast link is bi-directional, so peer UEs of UE-1 can send ProSe data to UE-1 over the unicast link with UE-1.

[…]

6.4.3.6 layer 2 link management through PC5 reference point for 5G ProSe UE to network relay

Layer 2 link procedures through PC5 reference point as depicted from clause 6.4.3.1 to clause 6.4.3.5 for unicast mode 5G ProSe direct communication can be used for PC5 reference point between 5G ProSe remote UE and 5G ProSe UE to network relay with the following differences and elucidations:

layer 2 link adaptation procedures are applicable to ProSe communication via 5G ProSe layer 3UE to network relay, other procedures are applicable to ProSe communication via 5G ProSe layer 2UE to network relay and ProSe communication via 5G ProSe layer 3UE to network relay.

UE-1 for the 5G ProSe remote UE and UE-2 for the 5G ProSe UE to network relay use UE-oriented layer 2 link setup. For other procedures, UE-1 represents a 5G ProSe remote UE and UE-2 represents a 5G ProSe UE to network relay, or UE-1 represents a 5G ProSe UE to network relay and UE-2 represents a 5G ProSe remote UE. That is, layer 2 link establishment is initiated by the 5G ProSe remote UE, while other procedures may be initiated by the 5G ProSe remote UE or by the 5G ProSe UE to network relay.

For UE-oriented layer 2 link setup as described in clause 6.4.3.1,

in step 1, the 5G ProSe remote UE determines a destination layer 2ID for PC5 unicast link establishment based on the unicast source layer 2ID of the selected 5G ProSe UE to network relay (as specified in clause 5.8.3) during UE to network relay discovery as specified in clause 6.3.2.3.

In step 2, the 5G ProSe remote UE (UE-1) determines the relay service code to be used. The relay service code to be used is a received relay service code selected from during UE-to-network relay discovery as specified in clause 6.3.2.3.

-in step 3, the 5G ProSe remote UE (UE-1) sends a unicast direct communication request message to the selected 5G ProSe UE-to-network relay. The destination layer 2ID used to send the direct communication request message should be the unicast layer 2ID as determined in step 1. The direct communication request message includes:

-source user information: the identity (i.e., user information ID) of the remote UE requesting the relay operation.

Note 1: the details of the one or more additional identities of the remote UE to be included during layer 2 link establishment will be determined by the SA WG 3.

-target user information: the identity (i.e., user information ID) of the UE-to-network relay to the 5G ProSe remote UE is provided during the UE-to-network relay discovery procedure.

-relay service code: indicating connectivity services provided by the 5G ProSe UE-to-network relay as requested by the 5G ProSe remote UE.

Security information: information for establishing security.

In step 4 and step 5, if the identity of the 5G ProSe UE-to-network relay matches the target user information and the relay service code is one of the relay service codes contained during UE-to-network relay discovery as specified in clause 6.3.2.3, then step 4a and step 5a are performed. The source user information in the direct communication accept message is the identity of the UE to network relay (i.e., user information ID). In the case of 5G ProSe layer 2 UE-to-network relay, the remote UE does not send IP address configuration, link local IPv6 address, and QoS information to the 5G ProSe layer 2 UE-to-network relay, and the direct communication accept message does not contain IP address configuration, link local IPv6 address, and QoS information. In the case of 5G ProSe layer 3UE to network relay, the direct communication accept message does not contain the IP address configuration of the indicated value "do not support address allocation".

In case of 5G ProSe layer 2UE to network relay, step 6 is not performed.

For a link identifier update as described in clause 6.4.3.2,

-the application layer ID is replaced by the user information ID.

In case of 5G ProSe layer 2UE to network relay, the changed identifier does not contain an IP address/prefix.

For layer 2 link release as described in clause 6.4.3.3,

in step 1, if the layer 2 link release procedure is initiated by a 5G ProSe UE to network relay, the disconnect request message may indicate that the 5G ProSe UE to network relay is temporarily unavailable, as described in clause 5.12.

And (2) injection: the form of the temporary unavailability indication will be determined by stage 3.

-if the service authorization for acting as a 5G ProSe remote UE or 5G ProSe UE to network relay is revoked, then the 5G ProSe remote UE or 5G ProSe UE to network relay should initiate release of the layer 2 link affected by the revoked authorization.

-upon receiving an indication from its AS layer that the PC5-RRC connection has been released AS specified in TS 38.300[12], the release of the layer 2 link from the 5 gpp rose layer 2 remote UE or the 5G ProSe layer 2UE to the network relay is initiated.

And (3) injection: the time at which the layer 2 link release is initiated depends on the UE implementation.

If the existing unicast links are established with different relay service codes or without a relay service code, then the 5G ProSe remote UE and the 5G ProSe UE to network relay should set up separate PC5 unicast links.

Each PC5 unicast link for a 5G ProSe UE-to-network relay is associated with a unicast link profile, the profile comprising:

-user information ID and layer 2ID of the 5G ProSe remote UE; and

-user information ID and layer 2ID of 5G ProSe UE to network relay; and

-a relay service code; and

in case of 5G ProSe layer 3UE to network relay, network layer protocols and information about PC5 QoS flows.

The unicast link profile should be updated accordingly after the layer 2 link modification or layer 2 link identifier update.

3GPP TS 24.554 describes the following:

7.2.2 5G ProSe direct link establishment procedure

7.2.2.1 general rule

Depending on the type of 5G ProSe direct link setup procedure (i.e. UE-oriented layer 2 link setup or ProSe service-oriented layer 2 link setup in 3gpp TS 23.304[2 ]), the 5G ProSe direct link setup procedure is used to establish a 5G ProSe direct link between two UEs or to establish multiple 5G ProSe direct links. The UE that sends the request message is referred to as the "initiating UE" and the other UE is referred to as the "target UE". If the request message does not indicate a particular target UE (i.e., the target user information is not included in the request message) and the multiple target UEs are interested in the ProSe application indicated in the request message, the initiating UE should handle the corresponding response messages received from those target UEs. The maximum number of 5G ProSe direct links established in the UE at a time should not exceed the implementation specific maximum number of 5G ProSe direct links established.

And (3) injection: the recommended maximum number of 5G ProSe direct links established is 8.

[…]

7.2.2.5 5G ProSe direct link establishment procedure not accepted by target UE

If the PROSE direct link establishment request message is not acceptable, the target UE should send a PROSE direct link establishment rejection message. The PROSE direct link setup rejection message contains a PC5 signaling protocol cause IE set to one of the following cause values:

#1 does not allow direct communication with the target UE;

#3 detects a collision of layer 2 IDs for unicast communication;

#5 lacks resources for the 5G ProSe direct link;

#13 congestion situation;

the security procedure of #14 5g ProSe UE to network relay fails; or (b)

#111 unspecified protocol error.

[…]

If the 5G ProSe direct link setup fails because the implementation specific maximum number of established 5G ProSe direct links or other temporary lower layer problems causing resource constraints have been reached, the target UE should send a ProSe direct link setup reject message containing the PC5 signaling protocol cause value #5 "lack resources for 5G ProSe direct link".

[…]

Table 10.2.1.8 entitled "PROSE PC5 discovery message for UE-to-network Relay discovery Notification" of [3GPP TS 24.554V17.1.0 ] is reproduced as FIG. 7]

[…]

11.2.14RRC container

The RRC container information element is used to indicate RRC container information received from a lower layer.

The RRC container is a type 4 information element.

The RRC container information element is decoded as shown in figure 11.2.14.1 and table 11.2.14.1.

Fig. 11.2.14.1 entitled "RRC container information element" of 3GPP TS 24.554V17.1.0 is reproduced as fig. 8]

The table 11.2.14.1 named "RRC container information element" of 3GPP TS 24.554V17.1.0 is reproduced as fig. 9]

The architecture and protocol stack for UE-to-network relay is presented by 3gpp TR 38.836 as follows:

4.5 Layer 2 relay

4.5.1 Architecture and protocol stack

4.5.1.1 protocol stack

Protocol stacks for the user plane and control plane of the relay architecture for L2 UE to network are described in fig. 4.5.1.1-1 and 4.5.1.1-2 for the case where the adaptation layer is not supported at the PC5 interface and fig. 4.5.1.1-3 and 4.5.1.1-4 for the case where the adaptation layer is supported at the PC5 interface.

For L2 UE-to-network relay, an adaptation layer is placed above the RLC sublayer for relaying CP and UP at the Uu interface between the UE and the gNB. Uu SDAP/PDCP and RRC terminate between the remote UE and the gNB, while RLC, MAC and PHY terminate in each link (i.e., the link between the remote UE and the UE-to-network relay UE and the link between the UE-to-network relay UE and the gNB). Whether the adaptation layer is also supported at the PC5 interface between the remote UE and the relay UE depends on the WI stage (assuming that the downward selection is first made before the detailed PC5 adaptation layer functionality is studied too much).

[…]

Fig. 4.5.1.1-3 entitled "user plane protocol stack for L2 UE to network relay (support adaptation layer at PC5 interface)" of [3GPP TS 38.836V17.0.0 is reproduced as fig. 10]

Fig. 4.5.1.1-4 entitled "control plane protocol stack for L2 UE to network relay (support adaptation layer at PC5 interface)" of [3GPP TS 38.836V17.0.0 is reproduced as fig. 11]

4.5.1.2 adaptation layer functionality

For L2 UE to network relay, for uplink:

the Uu adaptation layer at the relay UE supports UL bearer mapping between the ingress PC5 RLC channel for relay and the egress Uu RLC channel on the relay UE Uu path. For uplink relay traffic, different end-to-end RBs (SRBs, DRBs) of the same remote UE and/or different remote UEs may be subject to N:1 mapping and data multiplexing on one Uu RLC channel.

Remote UE identification (multiplexing data from multiple remote UEs) for UL traffic is supported using Uu adaptation layer. The remote UE Uu radio bearer and the identity information of the remote UE are included in the Uu adaptation layer at UL such that the gNB correlates received data packets for a particular PDCP entity associated with the correct remote UE Uu radio bearer of the remote UE.

For L2 UE to network relay, for downlink:

The Uu adaptation layer may be used to support DL bearer mapping at the gNB to map the end-to-end radio bearers (SRBs, DRBs) of the remote UE into the Uu RLC channel on the relay UE Uu path. The Uu adaptation layer may be used to support DL N:1 bearer mapping and data multiplexing between multiple end-to-end radio bearers (SRBs, DRBs) of a remote UE and/or different remote UEs and one Uu RLC channel on the relay UE Uu path.

The Uu adaptation layer needs to support remote UE identification for downlink traffic. The identification information of the remote UE Uu radio bearer and the identification information of the remote UE need to be placed by the gNB in the Uu adaptation layer at DL in order for the relay UE to map data packets received from the remote UE Uu radio bearer to its associated PC5 RLC channel.

3GPP TS 38.331 introduces the following:

5.3.3RRC connection establishment

5.3.3.1 general rules

[3GPP TS 38.331V17.0.0 entitled "RRC connection setup, successful" FIG. 5.3.3.1-1 was reproduced as FIG. 12]

[…]

The purpose of this procedure is to establish an RRC connection. RRC connection establishment involves SRB1 establishment. The procedure is also used to transfer initial NAS specific information/messages from the UE to the network.

[…]

5.3.5.5.2 with synchronous reconfiguration

The UE will perform the following actions to perform the reconfiguration with synchronization.

1> if the AS security is not activated, then performing an action after going to rrc_idle AS specified in 5.3.11, release reason for "other", after which the procedure ends;

1> if DAPS bearer is not configured:

2> stop timer T310 (if running) for SpCell;

1> if this procedure is performed for MCG:

2> if timer T316 is running;

3> stop timer T316;

3> clearing the information contained in VarRLF-Report, if present;

2> resumes MCG transfer (if suspended).

1> stop timer T312 for the corresponding SpCell (if running);

1> if sl-PathSwitchConfig is included:

2> treat the target L2U 2N relay UE as a UE indicated by targetRelayUEIdentity in sl-PathSwitchConfig;

2> starting a timer T420 for the corresponding target L2U 2N relay UE, wherein the timer value is set to T420 as contained in sl-PathSwitchConfig;

2> apply newUE-Identity value as C-RNTI;

2> if required, performing a PC5-RRC connection establishment with the target L2U 2N relay UE indicated by targetracueidentity;

2> apply the preset configuration of SL-RLC1 as defined in 9.2.4 to SRB1;

1> otherwise (not including sl-PathSwitchConfig):

2> if this procedure is performed for MCG, or if it is performed for SCG that is not indicated for deactivation in E-UTRA or NR RRC message in which rrcrecon configuration message is embedded:

3> start timer T304 for the respective SpCell, wherein the timer value is set to T304, as contained in reconfigurationWithSync;

2> if a frequencyInfoDL is included:

3> consider the target SpCell as a SpCell on SSB frequency indicated by frequencyInfoDL, which has a physical cell identity indicated by a physCellId;

2> otherwise:

3> regarding the target SpCell as the SpCell on the SSB frequency of the source SpCell, which has a physical cell identity indicated by the physCellId;

2> initiate DL synchronization with the target SpCell;

2> apply the specified BCCH configuration defined in 9.1.1.1 to the target SpCell;

2> obtain MIB of target SpCell, which is scheduled as specified in TS 38.213[13 ];

note 1: the UE should perform the reconfiguration with synchronization as soon as possible after receiving the RRC message triggering the reconfiguration with synchronization, possibly before acknowledging successful reception (HARQ and ARQ) of this message.

And (2) injection: the UE may omit reading MIB if the UE already has the required timing information, or the timing information is not needed for random access.

Note 2a: the UE with the DAPS bearer does not listen for system information updates in the source PCell.

2> if there are any DAPS bearers configured:

3> creating a MAC entity for the target cell group having the same configuration as the MAC entity for the source cell group;

3> for each DAPS bearer:

4> establishing an RLC entity or an entity for the target cell group having the same configuration as the entity for the source cell group;

4> establishing a logical channel for the target cell group having the same configuration as the channel for the source cell group;

note 2b: to understand, if the DAPS bearer is configured, the UE needs to check whether the field DAPS-Config exists within RadioBearerConfig IE received in the radioBearerConfig or radioBearerConfig 2.

3> for each SRB:

4> establishing RLC entities for the target cell group having the same configuration as the entities for the source cell group;

3> suspending SRBs for the source cell group;

and (3) injection: empty space

3> applying the value of newUE-Identity as the C-RNTI in the target cell group;

3> configuring the lower layer for the target SpCell according to the received spCellConfigCommon;

3> if any additional fields not previously covered are included in the received reconfigurationWithSync, the lower layer for the target SpCell is configured according to the additional fields.

2> otherwise:

3> resetting the MAC entity of the group of cells;

3> treat scells (if configured) of this cell group not included in SCellToAddModList of rrcrecon configuration message as being in deactivated state;

3> apply the value of newUE-Identity as the C-RNTI for this cell group;

3> configuring the lower layer according to the received spCellConfigCommon;

3> if any additional fields not previously covered are included in the received reconfigurationWithSync, the lower layer is configured according to the additional fields.

2> if the UE is connected with an L2U 2N relay UE (i.e., the UE is an L2U 2N remote UE at the source side):

3> performs PC5-RRC connection release as specified in 5.8.9.5.

[…]

5.3.7RRC connection re-establishment

5.3.7.1 general rule

[3GPP TS 38.331V17.0.0 entitled "RRC connection reestablishment, successful" FIG. 5.3.7.1-1 is reproduced as FIG. 13]

[…]

The purpose of this procedure is to re-establish the RRC connection. The procedure may be initiated for UEs in rrc_connected for which AS security has been activated in SRB2 and at least one DRB/multicast MRB setting or for which the IAB is SRB2, in order to continue the RRC connection. If the network is able to find and verify a valid UE context, or if the UE context cannot be retrieved and the network responds with an RRCSetup according to section 5.3.3.4, then the connection re-establishment is successful.

[…]

5.3.7.2 initiate

The UE initiates the procedure when one of the following conditions is met:

1> according to 5.3.10, after detecting a radio link failure of the MCG and t316 is not configured; or (b)

1> according to 5.3.10, after detecting a radio link failure of the MCG when SCG transmission is suspended; or (b)

1> according to 5.3.10, after detecting a radio link failure of the MCG when a PSCell change or PSCell addition is in progress; or (b)

1> following reconfiguration with a synchronization failure of MCG according to clause 5.3.5.8.3; or (b)

1> according to clause 5.4.3.5, after moving due to NR failure; or (b)

1> after an integrity check failure indication from the lower layer regarding SRB1 or SRB2, unless an integrity check failure is detected on the rrcreesctable message; or (b)

1> according to clause 5.3.5.8.2, after RRC connection reconfiguration failure; or (b)

1> upon detection of radio link failure for SCG when MCG transmission is suspended according to clause 5.3.10.3 in NR-DC or according to clause 5.3.11.3 of TS 36.331[10] in NE-DC; or (b)

1> according to clause 5.3.5.8.3, after reconfiguration with synchronization failure of SCG when MCG transfer is suspended; or (b)

1> according to TS 36.331[10] clause 5.3.5.7a, after failure of SCG change when MCG transfer is suspended; or (b)

1> following SCG configuration failure when MCG delivery is suspended according to clause 5.3.5.8.2 in NR-DC or according to TS 36.331[10] clause 5.3.5.5 in NE-DC; or (b)

1> after an integrity check failure indication for SRB3 from the lower layer of SCG when MCG is suspended; or (b)

1> according to clause 5.7.3b.5, after expiration of T316; or (b)

1> according to clause 5.8.9.3, after the L2U 2N remote UE in rrc_connected detects a side-link radio link failure; or (b)

1> according to clause 5.8.9.10, after the L2U 2N remote UE in rrc_connected receives the notifiationless sidelink containing the indirection type.

[…]

5.5 Measurement of

5.5.1 Introduction to the invention

The network may configure the rrc_connected UE to perform the measurement. The network may configure the UEs to report them according to the measurement configuration or perform conditional reconfiguration evaluation according to the conditional reconfiguration. The measurement configuration is provided by means of dedicated signalling, i.e. using rrcrecon configuration or rrcreseume.

The network may configure the UE to perform the following types of measurements:

-NR measurement;

-inter-RAT measurement of E-UTRA frequencies;

-inter-RAT measurement of UTRA-FDD frequency;

-NR side link measurement for L2U 2N relay UE.

The network may configure the UE to report the following measurement information based on SS/PBCH blocks:

-measurement results per SS/PBCH block;

-per cell measurement based on SS/PBCH blocks;

-SS/PBCH block index.

The network may configure the UE to report the following measurement information based on CSI-RS resources:

-measurement results per CSI-RS resource;

-measurements per cell based on CSI-RS resources;

-CSI-RS resource measurement identifiers.

The network may configure the UE to perform the following types of measurements for the NR side link and the V2X side link:

-CBR measurement.

The network may configure the UE to report the following CLI measurement information based on SRS resources:

-a measurement result per SRS resource;

-SRS resource index.

The network may configure the UE to report the following CLI measurement information based on CLI-RSSI resources:

-measurements per CLI-RSSI resources;

-CLI-RSSI resource index.

The network may configure the UE to report the following Rx-Tx time difference measurement information based on CSI-RS or PRS for tracking:

UE Rx-Tx time difference measurement.

[…]

-CellGroupConfig

CellGroupConfig IE are used to configure a primary cell group (master cell group, MCG) or secondary cell group (secondary cell group, SCG). The cell group includes one MAC entity, a set of logical channels with associated RLC entities, and a primary cell (SpCell) and one or more secondary cells (scells).

CellGroupConfig information element

/>

This message is used to transmit the handover command generated by the target gNB.

The direction is: target gNB to source gNB/source RAN.

HandoverCommand message

/>

-HandoverPreparationInformation

This message is used to transmit NR RRC information used by the target gNB, including UE capability information, e.g., during handover preparation or UE context retrieval in case of recovery or re-establishment. This message is also used to transfer information between the CU and the DU.

The direction is: source gNB/source RAN to target gNB or CU to DU.

HandoverPrepartionInformationMessaging

/>

3GPP R2-2206823 describes the following:

5.5.5 measurement reporting

5.5.5.1 general rule

[ FIG. 5.5.5.1-1 of 3GPP R2-2206823 entitled "measurement report" is reproduced as FIG. 14]

The purpose of this procedure is to transfer the measurement results from the UE to the network. The UE will initiate this procedure only after successful activation of the AS security.

For the measId triggered by the measurement report procedure, the UE should set the measResults within the MeasurementReport message as follows:

1> setting the measId as the measurement identity that triggers the measurement report;

1> for each serving cell configured with servingCellMO:

2> if reportConfig associated with measId triggering measurement report contains rsType:

3> if a serving cell measurement based on rsType contained in reportConfig that triggers a measurement report is available:

4> setting measResultServingCell within measResultServingMOList to contain RSRP, RSRQ and available SINR of the serving cell derived based on rsType contained in reportConfig triggering the measurement report;

2> otherwise:

3> if SSB-based serving cell measurements are available:

4> setting measresultservingcells within the measResultServingMOList to contain RSRP, RSRQ and available SINR for the serving cell derived based on SSB;

3> otherwise if CSI-RS based serving cell measurements are available:

4> setting measresultservingcells within the measResultServingMOList to contain RSRP, RSRQ and available SINR for the serving cell derived based on CSI-RS;

1> setting servCellId within measResultServingMOList to contain each NR serving cell configured with servingCellMO (if present);

1> if reportConfig associated with measId triggering measurement report contains reportcontytirs-indices and maxNrofRS-IndexesToReport:

2> including beam measurement information according to the associated reportConfig for each serving cell configured with servingCellMO, as described in 5.5.5.2;

1> if the reportConfig associated with measId triggering measurement report contains reportAddNeighMeas:

2> for each measObjectId referenced in the measIdList that also references servingCellMO, except the measObjectId corresponding to the measId that triggered the measurement report:

3> if measObjectNR indicated by servingCellMO contains RS resource configuration corresponding to rsType indicated in reportConfig:

4> with the highest measured RSRP if RSRP measurement is available for the cell corresponding to this measObjectNR, otherwise with the highest measured RSRQ if RSRQ measurement is available for the cell corresponding to this measObjectNR, and otherwise with the highest measured SINR, setting measresultacestneighbor cells within the measresuservingmobile to contain the physiocellid and the available measurement quantity based on reportQuantityCell and rsType indicated in reportConfig of the non-serving cell corresponding to the measObjectNR of interest;

4> if reportConfig associated with measId triggering measurement report contains reportcontytirs-indices and maxNrofRS-IndexesToReport:

5> for each best non-serving cell contained in the measurement report:

6> including beam measurement information according to the associated reportConfig as described in 5.5.5.2;

1> if reportConfig associated with measId triggering measurement report is set to eventTriggered and eventID is set to eventA3 or eventA4 or eventA5 or eventB1 or eventB2:

2> if the UE is in NE-DC and the measurement configuration triggering this measurement report is associated with MCG:

3> measresultservfreqlistutra-SCG is set to contain an entry for each E-UTRA SCG service frequency with:

4> carrier freq containing E-UTRA service frequencies;

4> setting measResultServingCell to contain available measurement quantities, the UE being configured to measure the available measurement quantities by a measurement configuration associated with the SCG;

4> if reportConfig associated with measId triggering measurement report contains reportcondeighmeas:

5> setting measresultservfreqlistutra-SCG to an amount including the best non-serving cell within the measresultbetneigcell based on RSRP on the service frequency of interest;

1> if reportConfig associated with measId triggering measurement report is set to eventTriggered and eventID is set to eventA3 or eventA4 or eventA5:

2> if the UE is at NR-DC and the measurement configuration triggering this measurement report is associated with MCG:

3> measResultServFreqListNR-SCG is set to contain the following for each NR SCG serving cell configured with servingCellMO (if present):

4> if reportConfig associated with measId triggering measurement report contains rsType:

5> if the serving cell measurement based on rsType contained in reportConfig triggering the measurement report is available according to the measurement configuration associated with SCG:

6> setting measResultServingCell within measresultservfreqlisttnr-SCG to contain RSRP, RSRQ and available SINR of serving cell derived based on rsType contained in reportConfig triggering measurement report;

4> otherwise:

5> if SSB-based serving cell measurements are available according to the measurement configuration associated with SCG:

6> setting measResultServingCell within measresultservfreqlisttnr-SCG to contain RSRP, RSRQ and available SINR of the serving cell derived based on SSB;

5> otherwise if CSI-RS based serving cell measurements are available according to the measurement configuration associated with SCG:

6> setting measResultServingCell within measresultservfreqlisttnr-SCG to contain RSRP, RSRQ and available SINR of serving cell derived based on CSI-RS;

4> if the SSB derived result of the serving cell is contained:

5> including ssbFrequency to a value indicated by ssbFrequency included in a MeasObjectNR of the serving cell;

4> if the result of the serving cell derived based on CSI-RS is contained:

5> including refFreqCSI-RS to a value indicated by refFreqCSI-RS included in MeasObjectNR of the serving cell;

5> for each serving cell configured with servingCellMO, including beam measurement information according to the associated reportConfig as described in 5.5.5.2, wherein availability is considered according to a measurement configuration associated with SCG;

5> if measObjectNR indicated by servingCellMO contains RS resource configuration corresponding to rsType indicated in reportConfig:

6> with highest measured RSRP if RSRP measurement is available for the cell corresponding to this measObjectNR, otherwise with highest measured RSRQ if RSRQ measurement is available for the cell corresponding to this measObjectNR, and otherwise with highest measured SINR, setting measresultservfreqlisttnr-SCG to contain one entry with a physiscellid and available measurement quantity based on reportQuantityCell and rsType indicated in reportConfig for the non-serving cell corresponding to the measObjectNR of interest, wherein availability is considered according to the measurement configuration associated with SCG;

7> if reportConfig associated with measId triggering measurement report contains reportcontytirs-indices and maxNrofRS-IndexesToReport:

8> for each best non-serving cell contained in the measurement report:

9> including beam measurement information according to an associated reportConfig as described in 5.5.5.2, wherein availability is considered according to a measurement configuration associated with the SCG;

1> if measRSSI-ReportConfig is configured within the corresponding ReportConfig for this measId:

2> setting rsti-Result to be a linear average of sample values provided by the lower layer in reportInterval;

2> setting the channelOccupiecy to a rounded percentage of all sample values in reportInterval that exceeds the channelOccupiethreshold sample value;

1> if the UE acts as an L2U 2N remote UE:

2> setting SL-MeasResultServingRelay to SL-RSRP containing the serving L2U 2N relay UE;

note 1: in the absence of data transfer from the L2U 2N relay UE to the L2U 2N remote UE, it is determined by the UE implementation whether to use SL-RSRP or SD-RSRP when setting up the SL-MeasResultServingRelay serving the L2U 2N relay UE.

1> if there is at least one applicable neighbor cell and/or candidate L2U 2N relay UE to report:

2> if reportType is set to eventTriggered or periodic:

3> if the measurement report relates to candidate L2U2N relay UE:

4> the sl-measresultschelltscandrelay in measresultneigcells is set to contain at most maxReportCells of best candidates L2U2N relay UEs according to the following:

5> if reportType is set to eventTriggered:

6> L2U2N relay UE contained in the delaysTriggeredList defined within the VarMeasRefortList for this measId;

5> otherwise:

6> applicable L2U2N relay UEs containing new measurement results become available since the last periodic report or since the measurement was initiated or reset;

5> for each L2U2N relay UE contained in the sl-measresultscundrelay:

6> contains sl-Relay UE-Identity;

5> for each involved L2U2N relay UE, the layer 3 filtered measurements are included according to reportConfig for this measId, ordered as follows:

6> the sl-MeasResult is set to one or more quantities indicated in reportQuantityRelay contained within the reportconfigclay concerned in descending order of the sorting quantity determined as specified in 5.5.5.3, i.e. the best L2U2N relay UE is contained first;

[…]

1> otherwise:

2> submit the MeasurementReport message to the lower layer for transfer, after which the program ends immediately;

[…]

5.8.3 side link UE information for NR side link communication

5.8.3.1 general rule

5.8.3.1-1 entitled "side Link UE info for NR side Link communication" of 3GPP R2-2206823 is reproduced as FIG. 15]

The purpose of this procedure is to inform the network of the UE:

of interest for receiving or transmitting NR side link communications or no longer of interest,

requesting allocation or release of transmission resources for NR side link communication,

QoS parameters and QoS profiles related to NR side link communication are being reported,

reporting that a side chain radio link failure or a side chain RRC reconfiguration failure has been detected,

side link UE capability information of an associated peer UE being reported for unicast communication,

RLC mode information of the side link data radio bearer received from the associated peer UE for unicast communication is being reported,

the side link DRX configuration received from the associated peer UE for NR side link unicast communication is being reported,

side link DRX assistance information received from associated peer UEs for NR side link unicast communication is being reported,

for NR side link multicast or broadcast communication, reporting [ further study of additional information ],

for NR-side link multicast or broadcast communication, the destination layer 2ID and QoS profile associated with its service of interest to which the application-side link DRX is being reported,

When the UE is a TX UE and is performing side link operation in resource allocation mode 1, DRX configuration reject information from its associated peer RX UE is being reported,

-reporting parameters related to U2N relay operation.

The editor annotates: further investigation of the additional information/Tx attribute set, during waiting for the reply of SA2, involves WA "if SA2 confirms that it is feasible (if the mapping from L2id to Tx attribute set is possible in the gNB (similar to what we do in LTE)), then no additional RAN2 work is required.

5.8.3.2 initiate

A UE in rrc_connected capable of NR side link communication or NR side link discovery or NR side link U2N relay operation may initiate a procedure to instruct it to (care for) receive or transmit NR side link communication or NR side link discovery or NR side link U2N relay operation in several cases including after successful connection establishment or restoration, after a change of care, after a change of QoS profile, after receiving uecapabilityinformation uplink from an associated peer UE, after updated RLC mode information from an associated peer UE, or after a change to a PCell providing SIB12 containing sl-ConfigCommonNR. A UE capable of NR side link communication may initiate a procedure requesting allocation of dedicated side link DRB configuration and transmission resources for NR side link communication transmission. A UE capable of NR side link communication may initiate a procedure to report to the network that a side link radio link failure or a side link RRC reconfiguration failure has been declared. A NR side link discovery capable UE may initiate a procedure requesting allocation of dedicated resources for side link discovery transmission or side link discovery reception. The U2N relay operation capable UE may initiate a procedure to report/update parameters (including the source L2ID of the L2 remote UE) for acting as a U2N relay UE or a U2N remote UE.

A NR side link communication capable UE in rrc_connected may initiate a procedure to report the side link DRX configuration received from the associated peer UE for NR side link unicast communication upon receiving the side link DRX configuration from the associated peer UE. A UE capable of NR side link communication that is in rrc_connected and is performing side link operation with resource allocation mode 1 may initiate a procedure of reporting side link DRX assistance information received from an associated peer UE for NR side link unicast communication upon receiving side link DRX assistance information from the associated peer UE.

An RX UE capable of NR side link communication in RRC_CONNECTED can initiate a procedure to report destination layer 2ID and QoS profile associated with its service of interest for the NR side link DRX application for multicast or broadcast communication.

After initiating this procedure, the UE should:

1> if SIB12 containing sl-ConfigCommonNR is provided by PCell:

2> ensure that there is a valid version of SIB12 for PCell;

2> if configured by the upper layer to receive NR side link communication on the frequencies contained in the sl-FreqInfoList in SIB12 of PCell:

3> if the UE does not transmit the sidelinkiueinformationnr message since the last entry into the rrc_connected state; or (b)

3> if the UE is connected to the PCell that does not provide SIB12 containing sl-ConfigCommonNR since the last time the UE transmitted the sidelinkueinfo information nr message; or (b)

3> if the last transmission of the SidelinkUEInformationNR message does not contain sl-RxIntersetedFreqList; or if the frequency of link communication configured by the upper layer to receive the NR side has changed since the last transmission of the sidinkueinfo information NR message:

4> according to 5.8.3.3, initiating transmission of a sidechain communication reception frequency of interest by a sidechain ueinformationnr message;

3> if the UE receives a side link DRX configuration for NR side link unicast communication from an associated peer UE and the UE accepts the side link DRX configuration:

4> initiating transmission of a sidelinkueinfformationnr message to report the side link DRX configuration according to 5.8.3.3;

3> if the UE is an RX UE for NR side link multicast or broadcast communication and is interested in the service of side link DRX applications:

4> initiating transmission of a SidelinkUEInformationNR message to report a destination layer 2ID and QoS profile associated with a service according to 5.8.3.3;

2> otherwise:

3> if the last transmission of the SidelinkUEInformationNR message contains an sl-RxIntersetdFreqList:

4> according to 5.8.3.3, initiating transmission of a sidechain communication message to indicate that it is no longer concerned with NR sidechain communication reception;

2> if configured by the upper layer to transmit non-trunked NR communications on frequencies contained in the sl-FreqInfoList in SIB12 of PCell:

3> if the last transmission of the SidelinkUEInformationNR message does not contain an sl-TxResourceReqList; or if the information carried by the sl-txresource reqlist has changed since the last transmission of the siderueinfomation nr message:

4> initiating transmission of a SidelinkUEInformationNR message according to 5.8.3.3 to indicate NR side link communication transmission resources required by the UE;

3> if the UE receives side link DRX assistance information for NR side link unicast communication from the associated peer UE:

4> initiating transmission of a sidelink DRX assistance information, sidelink ueinfo information nr message according to 5.8.3.3;

2> otherwise:

3> if the last transmission of the SidelinkUEInformationNR message contains an sl-TxResourceReqList:

4> according to 5.8.3.3, initiating transmission of a sidechain NR message to indicate that it no longer requires NR sidechain communication transmission resources;

2> if configured by the upper layer to receive the NR side link non-relay discovery message on the frequency contained in the sl-FreqInfoList in SIB12 containing the PCell of sl-non-relay discovery:

3> if the UE is connected to a PCell that does not provide SIB12 containing sl-ConfigCommonNR or to a PCell that provides SIB12 but does not contain sl-non-discovery since the last time the UE transmitted the sidinkueinformation nr message; or (b)

3> if the last transmission of the SidelinkUEInformationNR message does not contain sl-RxIntersetedFreqListDisc; or if the frequency at which the upper layer is configured to receive NR side link discovery messages has changed since the last transmission of the sidinkueinfo information NR message:

4> according to 5.8.3.3, initiating transmission of a sidechain communication NR message to indicate an NR sidechain discovery receive frequency of interest;

2> otherwise:

3> if the last transmission of the SidelinkUEInformationNR message contains sl-RxIntersetdFreqListdisc:

4> according to 5.8.3.3, initiating transmission of a sidechain NR message to indicate that it is no longer concerned with NR sidechain discovery message reception;

2> if configured by the upper layer to receive the NR side link L2U2N Relay discovery message on the frequency contained in the sl-FreqInfoList in SIB12 of the PCell containing the sl-L2U 2N-Relay; or if configured by the upper layer to receive the NR side link L3U2N relay discovery message on the frequency contained in the sl-FreqInfoList in SIB12 of the PCell containing the sl-L3U2N-relay discovery:

3> if the UE is connected to the PCell that does not provide SIB12 including sl-ConfigCommonNR or to the PCell that does not include SIB12 of sl-L2U2N-Relay, in case of L2U2N Relay operation, or to the PCell that provides SIB12 not including sl-L3U2N-Relay, in case of L3U2N Relay operation, since the last UE transmitted the sidueinformation nr message; or (b)

4> if the UE is capable of acting as a U2N relay UE, and if SIB12 contains sl-relay UE-ConfigCommon, and if the U2N relay UE threshold condition as specified in 5.8.14.2 is met; or (b)

4> if the UE is selecting a U2N relay UE/a selected U2N relay UE, and if SIB12 contains sl-RemoteUE-ConfigCommon, and if the U2N remote UE threshold condition as specified in 5.8.15.2 is met:

5> according to 5.8.3.3, initiating transmission of a sidechain communication NR message to indicate an NR sidechain discovery receive frequency of interest;

2> otherwise:

2> if configured by the upper layer to transmit the NR side link non-relay discovery message on the frequency contained in the sl-FreqInfoList in SIB12 containing the PCell of sl-non-relay discovery:

3> if the last transmission of the SidelinkUEInformationNR message does not contain sl-TxResourceReqListdisc; or if the information carried by the sl-txresource reqlistdisc has changed since the last transmission of the siderueinfformationnr message:

4> initiating transmission of a SidelinkUEInformationNR message according to 5.8.3.3 to indicate NR side link non-relay discovery message resources required by the UE;

2> otherwise:

3> if the last transmission of the SidelinkUEInformationNR message contains sl-TxResourceReqListdisc, then:

4> according to 5.8.3.3, initiating the transmission of a SidelinkUEInformationNR message to indicate that it no longer requires NR side link non-relay discovery message resources;

2> if configured by the upper layer to transmit the NR side link L2U2N Relay discovery message on the frequency contained in the sl-FreqInfoList in SIB12 of the PCell containing the sl-L2U 2N-Relay; or if configured by the upper layer to transmit an NR side link L3U2N relay discovery message on a frequency contained in an sl-FreqInfoList in SIB12 of the PCell containing sl-L3U2N-relay discovery:

5> according to 5.8.3.3, initiating transmission of a SidelinkUEInformationNR message to indicate NR side chain relay discovery message resources required by the UE;

2> otherwise:

4> according to 5.8.3.3, initiating the transmission of a SidelinkUEInformationNR message to indicate that it no longer requires NR side chain relay discovery message resources;

2> if configured by the upper layer to transmit NR side link L2U2N Relay communications on frequencies contained in sl-FreqInfoList in SIB12 of the PCell containing sl-L2U 2N-Relay; or if configured by the upper layer to transmit NR side link L3U2N relay communications on frequencies contained in the sl-FreqInfoList in SIB12 of the PCell containing sl-L3U2N-relay discovery:

3> if the last transmission of the SidelinkUEInformationNR message does not contain sl-TxResourceReqL2U2N-Relay; or if the information carried by sl-txresource reql2U2N-Relay has changed since the last transmission of the siderueinfomation nr message:

2> otherwise:

5.8.3.3 actions related to the delivery of a SidelinkUEInformationNR message

The UE should set the content of the sidinkueinfo information nr message as follows:

1> if the UE initiates a procedure to indicate that it is (no longer) interested in receiving NR side link communication or requesting NR side link communication transport resources (configuration/release), or reports to the network that side link radio link failure or side link RRC reconfiguration failure has been declared, or reports to the network side link DRX configuration for NR side link unicast communication, or reports to the network side link DRX assistance information for NR side link unicast communication, or reports destination layer 2ID and QoS profile associated with its interested service for NR side link multicast or broadcast communication application side link DRX, or indicates that it is (no) interested in receiving NR side link discovery messages, or requesting NR side link discovery messaging resources (configuration/release), or requesting NR side link U2N relay communication transport resources (configuration/release) (i.e. the UE contains all involved information, irrespective of what triggered the procedure):

2> if SIB12 containing sl-ConfigCommonNR is provided by PCell:

3> if configured by the upper layer to receive NR side link communication:

4> contains sl-rxintersetedfreqlist and sets it to a frequency for NR side link communication reception;

4> contains sl-rxrx-ReportList and sets its fields (if needed) as follows for each destination it reports to the network:

5> if the SIB12-IE contains sl-DRX-ConfigCommon-GC-BC:

6> if received from the associated peer UE, then set sl-DRX-ConfigFromTx to a side link DRX configuration containing the accepted associated destination;

6> for an associated destination for NR side link multicast or broadcast communications, setting sl-rxintersetedqos-InfoList to contain the QoS profile of the service of interest to it;

3> if configured by the upper layer to carry non-relay NR side link communications:

4> contains sl-txresource reqlist and each destination for which the requesting network assigns NR side link communication resources sets its field (if needed) as follows:

5> setting the sl-DestinationIdentity as a destination identity configured by the upper layer for NR side link communication transport;

5> setting sl-CastType to the broadcast type of the associated destination identity configured by the upper layer for NR side link communication transmissions;

5> if the associated bi-directional side link DRB has been established due to the configuration of rrcrecnonfigurationsidelink, then the sl-RLC-ModeIndication is set to the QoS profile of the side link QoS flow containing RLC mode and optionally associated RLC mode;

5> setting sl-QoS-InfoList as a QoS profile containing a side link QoS flow configured by an upper layer for an associated destination of NR side link communication transmissions;

5> setting sl-intersetdfreqlist to a frequency indicating an associated destination for NR side link communication transmissions;

5> set sl-TypeTxSyncList to the current synchronization reference type used on the associated sl-intersetedfreqlist for NR side link communication transfer.

5> the sl-capabilityinfo information sip link is set to contain the UE capabilityinfo information sip link message (if present) received from the associated peer UE.

5> if sl-DRX-ConfigCommon-GC-BC is contained in SIB12-IE and the UE is configured with sl-SchedulConfig:

6> setting sl-DRX-infofrofrtrx to the side link DRX assistance information (if present) containing the associated destination received from the associated peer UE;

-editor annotates: the message for the Tx UE to report DRX configuration rejection information is to be further studied.

4> if a sidelink radio link failure or a sidelink RRC reconfiguration failure has been declared according to clauses 5.8.9.3 and 5.8.9.1.8, respectively;

5> contains sl-FailureList and sets its fields for each destination for which an NR side link communication failure is reported as follows:

6> setting the sl-DestinationIdentity as a destination identity configured by the upper layer for NR side link communication transport;

6> if side link RLF is detected as specified in clause 5.8.9.3:

7> set sl-Failure as rlf for the associated destination of the NR side link communication transfer;

6> otherwise, if rrcrecon configuration failure is received:

7> setting sl-Failure as configFailure for the associated destination of the NR side link communication transfer;

3> if SIB12 contains sl-NonRelayDiscopy and if configured by the upper layer to receive NR-side link non-Relay discovery messages, or if SIB12 contains sl-L2U2N-Relay and if configured by the upper layer to receive NR-side link L2U2N Relay discovery messages, or if SIB12 contains sl-L3U2N-Relay discovery and if configured by the upper layer to receive NR-side link L3U2N Relay discovery messages:

4> includes sl-rxinterrestedfreqlistdisc and sets it to a frequency for NR side link discovery message reception;

4> if the UE can be an L2U2N remote UE:

5> includes the sl-sourceinityremoteue and sets it to the source identity configured by the upper layer for NR side chain L2U2N relay communication transfer;

3> if SIB12 contains sl-NonRelayDiscopy and if configured by the upper layer to transmit NR-side link non-Relay discovery messages, or if SIB12 contains sl-L2U2N-Relay and if configured by the upper layer to transmit NR-side link L2U2N Relay discovery messages, or if SIB12 contains sl-L3U2N-Relay discovery and if configured by the upper layer to transmit NR-side link L3U2N Relay discovery messages:

4> includes sl-txresource reqlistdiscsi and each destination that assigns NR side chain discovery message resources for the requesting network sets its field (if needed) as follows:

5> setting sl-destinationidentity disc to the destination identity configured by the upper layer for NR side link discovery messaging;

5> if the UE acts as an L2U2N relay UE;

6> the sl-sourceidentityrelay ue is set to the source identity configured by the upper layer for NR side chain L2U2N relay discovery messaging;

5> setting sl-CastTypeDisc to the broadcast type of the associated destination identity configured by the upper layer for NR side link discovery messaging;

5> setting sl-txintersetedfreqlistdisc to indicate the frequency of the associated destination for NR side link discovery messaging;

5> setting sl-typetxsynclistdiscsi to the current synchronization reference type used on the associated sl-intersetedfreqlist for NR side link discovery messaging;

5> set sl-discovery type to the current discovery type of the associated destination identity configured by the upper layer for NR side link discovery messaging;

3> if SIB12 contains sl-L2U2N-Relay and if configured by the upper layer to transmit NR side chain L2U2N Relay communications and the UE acts as L2U2N Relay UE:

4> including sl-txresourcereqlistcomm Relay in sl-TxResourceReqL2U2N-Relay and setting its fields (if needed) for each destination to which the NR side link L2U2N Relay communication resource is assigned for the requesting network as follows:

5> setting sl-destinationidentity L2U2N as the destination identity configured by the upper layer for NR side link L2U2N relay communication transmissions;

5> setting sl-txintersetedfreqlistl 2U2N to a frequency indicating an associated destination for NR side link L2U2N relay communication transmissions;

5> setting sl-TypeTxSyncListL2U2N to the current synchronization reference type used on the associated sl-intersetfreqlistl 2U2N for NR side link L2U2N relay communication transmissions;

5> set sl-LocalID-Request to Request local ID for L2U2N remote UE;

5> set the sl-pageidentity remoteue to the paging UE ID received from the peer L2U2N remote UE;

5> the sl-capabilityinfo information sip link is set to contain the uecapabilityinfo sip link message (if present) received from the peer UE.

4> contains ue-Type and sets it to delayue;

3> if SIB12 contains sl-L2U2N-Relay and if the NR side chain L2U2N Relay communication is configured by the upper layer to be transmitted and the UE has a selected L2U2N Relay UE:

4> including sl-txresourcereqlistcomm Relay in sl-TxResourceReqL2U2N-Relay and setting its fields (if needed) as follows to request the network to assign NR side link L2U2N Relay communication resources:

4> contains ue-Type and sets it to remoteUE;

3> if SIB12 contains sl-L3U2N-relay discovery and if configured by the upper layer to transmit NR side link L3U2N relay communications:

4> including sl-txresourcereqlistcomm Relay in sl-TxResourceReqL3U2N-Relay and setting its fields (if needed) for each destination to which the NR side link L3U2N Relay communication resource is assigned for the requesting network as follows:

5> setting the sl-DestinationIdentity as a destination identity configured by the upper layer for NR side link L3U2N relay communication transfer;

5> setting sl-CastType to the broadcast type of the associated destination identity configured by the upper layer for NR side link L3U2N relay communication transmissions;

5> setting sl-QoS-InfoList as a QoS profile containing a sidelink QoS flow configured by an upper layer for an associated destination of NR sidelink L3U2N relay communication transmissions;

5> setting sl-txintersetedfreqlist to a frequency indicating an associated destination for NR side link L3U2N relay communication transmissions;

5> set sl-TypeTxSyncList to the current synchronization reference type used on the associated sl-intertedfreqlist for NR side link L3U 2N relay communication transfer.

4> contains UE-Type and sets it as a relay UE if the UE acts as an NR side chain L3U 2N relay UE, otherwise as a remoteUE;

1> if the UE initiates a procedure when connected to the E-UTRA PCell:

2> submit the SidelinkUEInformationNR via SRB1 to the lower layer embedded in the E-UTRA RRC message ULInformation TransferIRAT as specified in TS 36.331[10] clause 5.6.28;

1> otherwise:

2> submit the SidelinkUEInformationNR message to the lower layer for transmission.

[…]

5.8.9.1 side link RRC reconfiguration

5.8.9.1.1 general rule

[ FIG. 5.8.9.1.1-1 entitled "side chain RRC Reconfiguration, success" of 3GPP R2-2206823 was reproduced as FIG. 16]

[…]

The purpose of this procedure is to modify the PC5-RRC connection, e.g., to set up/modify/release the side link DRB or PC5 relay RLC channel, (reconfigure) NR side link measurement and reporting, (reconfigure) side link CSI reference signal resources and CSI reporting delay bounds.

The UE may initiate a side link RRC reconfiguration procedure and perform the operations in clause 5.8.9.1.2 on the corresponding PC5-RRC connection in the following cases:

release of sidelink DRB associated with peer UE as specified in clause 5.8.9.1a.1;

-establishment of a sidelink DRB associated with a peer UE, as specified in clause 5.8.9.1a.2;

-modification of parameters contained in SLRB-Config for side link DRB associated with peer UE as specified in clause 5.8.9.1a.2;

-releasing the PC5 relay RLC channel for the L2U 2N relay UE and the remote UE as specified in clause 5.8.9.7.1;

-establishing a PC5 relay RLC channel for the L2U 2N relay UE and the remote UE as specified in clause 5.8.9.7.2;

-modifying parameters contained in the SL-RLC-ChannelConfigPC5 for the PC5 relay RLC channel of the L2U 2N relay UE and the remote UE as specified in clause 5.8.9.7.2;

- (re) configuring peer UEs to perform NR sidelink measurements and reporting.

- (re) configuring side link CSI reference signal resources and CSI reporting latency bounds;

- (re) configuring the peer UE to perform side link DRX.

In rrc_connected, the UE applies the NR side link communication parameters provided in rrcrecon configuration (if present). In rrc_idle or rrc_inactive, the UE applies NR side link communication parameters provided in the system information (if present). For other cases, the UE applies NR side link communication parameters provided in the sidlinkpreconfignr (if present). When the UE performs a state transition between the above three cases, after acquiring the new configuration, the UE applies NR side link communication parameters provided in the new state. The UE continues to apply the NR side link communication parameters provided in the old state before acquiring the new configuration.

5.8.9.1.2 actions related to the delivery of RRCRECONfigure Sidelink messages

The UE shall set the content of the rrcrecon configuration sip link message as follows:

1> for each side link DRB to be released, according to clause 5.8.9.1a.1.1, due to sl-ConfigDedicatedNR, SIB, sidlinkpreconfignr or upper layer configuration:

2> setting SLRB-PC5-ConfigIndex contained in SLRB-ConfigToReleaseList corresponding to the side link DRB;

1> for each side link DRB to be established or modified, according to clause 5.8.9.1a.2.1, since sl-ConfigDedicatedNR, SIB12 or sidlinkpreconfignr is received:

2> setting slRB-Config contained in SLRB-ConfigtoadModList based on the received slR-radio BearerConfig and slR-RLC-BearerConfig corresponding to the side link DRB;

1> the sl-MeasConfig is set as follows:

2> if the frequency for NR side link communication is contained in the sl-FreqInfoToAddModList in the sl-ConfigDedimonium NR within the RRCReconfiguration message or in the sl-ConfigCommonNR within SIB 12:

3> if the UE is in rrc_connected:

4> setting sl-MeasConfig according to the NR side link measurement configuration information stored for this destination;

3> if the UE is in rrc_idle or rrc_inactive:

4> setting sl-MeasConfig according to the stored NR side link measurement configuration received from SIB 12;

2> otherwise:

3> setting sl-MeasConfig according to sl-measpreffig in the SidelinkPreconfigNR;

1> starting a timer T400 for the destination associated with the side link DRB;

1> setting sl-CSI-RS-Config;

1> set sl-latex boundsi-Report,

note 1: how to set the parameters contained in the sl-CSI-RS-Config and sl-latency boundsi-Report depends on the UE implementation.

1> the sl-DRX-ConfigUC-PC5 is set as follows:

3> if the UE is in rrc_connected and is performing side chain operation with resource allocation pattern 1:

4> setting sl-DRX-ConfigUC-PC5 according to the stored NR side link DRX configuration information for this destination.

3> otherwise if the UE is in rrc_connected and is performing side chain operation with resource allocation pattern 2:

4> UE determining a side link DRX configuration for unicast of the associated peer UE;

and (2) injection: if the UE is in RRC_IDLE or RRC_INACTIVE or out of coverage, then the sl-DRX-ConfigUC-PC5 is set by the UE embodiment.

1> for each PC5 relay RLC channel to be released due to the configuration of the sl-configdedicaternr:

2> setting a SL-RLC-ChannelID corresponding to a PC5 relay RLC channel in SL-RLC-channeltoreleaselist PC5;

1> for each PC5 relay RLC channel that will be established or modified due to receipt of the sl-configdedicaternr:

2> setting SL-RLC-ChannelConfigPC5 contained in SL-RLC-ChannelToAddModListPC5 according to the received SL-RLC-ChannelConfig corresponding to the PC5 relay RLC channel;

the UE will submit an rrcrecon configuration sip link message to the lower layer for transmission.

5.8.9.1.3UE receiving RRCRECONfigure Sidelink

The UE will perform the following actions after receiving the rrcrecon configuration sidelink:

1> if rrcrecon configuration sidelink contains sl-ResetConfig, then:

2> performing a side link reset configuration procedure, as specified in 5.8.9.1.10;

1> if rrcrecon configuration sidelink contains slrb-ConfigToReleaseList:

2> for each SLRB-PC5-ConfigIndex value contained in SLRB-ConfigToReleaseList as part of the current UE side link configuration;

3> according to clause 5.8.9.1a.1, performing a sidelink DRB release procedure;

1> if rrcrecon configuration sidelink contains slrb-configtoadmodlist:

2> for each slrb-PC5-ConfigIndex value contained in the slrb-configtoadmodlist that is not part of the current UE side link configuration:

3> if si-mappdqos-flowstoadlist is included:

4> applying SL-PQFI contained in SL-MappedQoS-FlowsToAddList;

3> according to clause 5.8.9.1a.2, performing a side link DRB addition procedure;

2> for each slrb-PC5-ConfigIndex value contained in the slrb-configtoadmodlist as part of the current UE side link configuration:

3> if si-mappdqos-flowstoadlist is included:

4> adding SL-PQFI contained in SL-mappdqos-flowstoadlist to the corresponding side link DRB;

3> if si-mappdqos-flowstroreleaselist is included:

4> removing SL-PQFI contained in SL-mappdqos-flowstroleaselist from the corresponding side link DRB;

3> if the side link DRB release condition as described in clause 5.8.9.1a.1.1 is satisfied:

4> performing a sidelink DRB release procedure according to clause 5.8.9.1a.1.2;

3> otherwise if the side link DRB modification condition as described in clause 5.8.9.1a.2.1 is satisfied:

4> performing a sidelink DRB modification procedure according to clause 5.8.9.1a.2.2;

1> if the rrcrecon configuration sidelink message contains sl-MeasConfig, then:

2> performing a side link measurement configuration procedure as specified in 5.8.10;

1> if the rrcrecon configuration sidelink message contains sl-CSI-RS-Config, then:

2> application side link CSI-RS configuration;

1> if the rrcrecon configuration sidelink message contains sl-LatencyBoundCSI-Report, then:

2> applying a configured side link CSI reporting delay bound;

1> if rrcrecon configuration sidelink contains sl-RLC-channeltoleleaselistpc 5:

2> for each SL-RLC-ChannelID value contained in SL-RLC-channeltorrelease listpc5 as part of the current UE side link configuration;

3> according to clause 5.8.9.7.1, performing a PC5 relay RLC channel release procedure;

1> if rrcrecon configuration sidelink contains sl-RLC-ChannelToAddModListPC5:

2> for each sl-RLC-ChannelID-PC5 value contained in sl-RLC-ChannelToAddModListPC5 that is not part of the current UE side link configuration:

3> according to clause 5.8.9.7.2, performing a side link RLC channel addition procedure;

2> for each sl-RLC-ChannelID-PC5 value contained in sl-RLC-ChannelToAddModListPC5 as part of the current UE side link configuration:

3> performing the PC5 relay RLC channel modification procedure according to clause 5.8.9.7.2;

1> if the UE is not able to follow the (partial) configuration contained in rrcrecon configuration sidelink (i.e. side link RRC reconfiguration failure):

2> continuing to use the configuration used prior to receipt of the rrcrecon configuration sidelink message;

2> setting the content of the RRCRECONfigure FailureSINEDLink message;

3> submit rrcrecon configuration failure message to lower layer for transmission;

1> otherwise:

2> setting the content of the RRCRECONfigure CompleteSideLink message;

3> submit rrcrecon configuration completesidlink message to lower layer for transmission;

note 1: when the same logical channel is configured by another UE for a different RLC mode, the UE handles the situation as a side link RRC reconfiguration failure.

[…]

-MeasResults

IE MeasResults cover the same frequency, different frequencies, inter-RAT mobility and measurement results of NR side link communication.

MeasResults information element

/>

The measurement results of the L2U 2N relay UE are covered by the-SL-MeasResultsRelayIE SL-MeasResultsRelay.

SL-measresultsray information element

/>

-CellAccessRelatedInfo

IE CellAccessRelatedInfo indicates cell access related information for this cell.

CellAccess RelatedInfo information element

The SideLinkUEInformationNR message is used to indicate NR side link UE information to the network.

Signaling radio bearers: SRB1

RLC-SAP:AM

Logical channel: DCCH (DCCH)

The direction is: UE to network

SidelinkUEInformationNR message

/>

Editor notes 1: the content of the side link DRX configuration determination assistance information is to be further investigated.

Editor notes 2: the inactivity timer to be included in the assistance information from RX UE to TX UE is to be further studied.

[…]

-SL-ConfigDedicatedNR

The IE SL-ConfigDedicatedNR specifies dedicated configuration information for link communication on the NR side.

SL ConfigDedimatiedNR information element

/>

The IE SL-L2Relay UE-Config is used to configure L2U 2N relay operation related configurations, e.g., SRAP-Config, used by the L2U 2N relay UE.

SL-L2Relay UE-Config information element

-SL-L2RemoteUE-Config

The IE SL-L2remote UE-Config is used to configure L2U 2N relay operation related configurations, e.g., SRAP-Config, used by the L2U 2N remote UE.

SL-L2remoteUE-Config information element

-SL-SRAP-Config

IE SL-SRAP-Config is used to set configurable SRAP parameters used by the L2U 2N relay UE and the L2U 2N remote UE, as specified in TS 38.351[66 ].

SL-SRAP-Config information element

/>

-SL-RLC-ChannelConfig

The IE SL-RLC-ChannelConfig specifies configuration information for the PC5 relay RLC channel between the L2U 2N relay UE and the L2U 2N remote UE.

SL-RLC-ChannelConfig information element

-SL-LogicalChannelConfig

The IE SL-LogicalChannelConfig is used to configure side link logical channel parameters.

SL LogicalchannelConfig information element

/>

The IE SL-RLC-Config is used to specify the RLC configuration of the side link DRB. RLC AM configurations are only suitable for unicast NR side link communications.

SL-RLC-Config information element

/>

The rrcrecon configuration message is a command to modify the RRC connection. It may convey information for measurement configuration, mobility control, radio resource configuration (including RB, MAC primary configuration, and physical channel configuration), and AS security configuration.

Signaling radio bearers: SRB1 or SRB3

RLC-SAP:AM

Logical channel: DCCH (DCCH)

The direction is: network to UE

RRCRECONfigure message

/>

RRCSetup RRCSetup message is used to set up SRB1.

Signaling radio bearers: SRB0RLC-SAP: TM

Logical channel: CCCH (CCCH)

The direction is: network to UE

RRCSetup message

/>

-RRCSetupComplete

The rrcrumeCondition message is used to confirm successful completion of the RRC connection setup.

Signaling radio bearers: SRB1

RLC-SAP:AM

Logical channel: DCCH (DCCH)

The direction is: UE to network

RRCSetup complete message

/>

The rrcsetup request message is used to request establishment of an RRC connection.

Signaling radio bearers: SRB0RLC-SAP: TM

Logical channel: CCCH (CCCH)

The direction is: UE to network

RRCSetup request message

/>

The rrcrecon configuration sip message is a command for the AS configuration of the PC5 RRC connection. It is only applied to unicast of NR side link communication.

Signaling radio bearers: SL-SRB3

RLC-SAP:AM

Logical channel: SCCH (SCCH)

The direction is: UE-to-UE

RRCRECONfigure Sidelink message

/>

9.4 radio information related to discovery messages

This clause specifies the RRC information element transmitted in the discovery message.

-SL-AccessInfo-L2U2N

The IE SL-AccessInfo-L2U2N contains the radio information contained in the discovery message for the L2U2N relay operation.

SL-Access info-L2U2N information element

/>

The IE SL-ServerCellInfo is used to indicate the serving cell information of the L2U2N remote UE.

SL-servingCellInfo information element

3GPP TS 38.300 introduces the following:

mobility in RRC_CONNECTED

9.2.3.1 overview

Network controlled mobility applies to UEs in rrc_connected and is classified into two types of mobility: cell-level mobility and beam-level mobility. Beam level mobility includes intra-cell beam level mobility and inter-cell beam level mobility.

Cell level mobility requirements trigger explicit RRC signaling, i.e. handover. For inter-gNB handover, the signaling procedure consists of at least the following basic components illustrated in FIG. 9.2.3.1-1:

[3GPP TS 38.300V17.0.0, FIG. 9.2.3.1-1 entitled "inter-gNB switching program" is reproduced as FIG. 17]

1. The source gNB initiates the handover and issues a handover request on the Xn interface.

2. The target gNB performs admission control and provides the new RRC configuration as part of the handover request acknowledgement.

3. The source gNB provides RRC configuration to the UE by forwarding the RRCRECONfigure message received in the handover request acknowledgement. The rrcrecon configuration message contains at least the cell ID and all information required to access the target cell so that the UE can access the target cell without reading the system information. For some cases, the information needed for contention-based and contention-free random access may be included in the rrcrecon configuration message. The access information to the target cell may contain beam specific information (if present).

The ue moves the RRC connection to the target gNB and replies with an rrcrecconfiguration complete.

Note 1: user data may also be sent in step 4 if granted permission.

[…]

3GPP R2-2206232 describes the following:

16.12.5.1RRC connection management

The L2U2N remote UE needs to establish its own PDU session/DRB with the network before user plane data transfer.

The NR V2X PC5 unicast link setup procedure may be used to set up a secure unicast link between the L2U2N remote UE and the L2U2N relay UE before the L2U2N remote UE establishes a Uu RRC connection with the network via the L2U2N relay UE.

The establishment of Uu SRB1/SRB2 and DRB for the L2U2N remote UE is subject to a Uu configuration procedure for L2 UE to network relay.

The advanced connection establishment procedure in the following diagram 16.12.5.1-1 is applicable to L2U2N relay:

fig. 16.12.5.1-1 entitled "procedure for L2U2N remote UE connection establishment" of 3gpp R2-2206232 is reproduced as fig. 18]

The L2U2N remote and L2U2N relay UEs perform discovery procedures and establish a PC5-RRC connection using an NR side link PC5 unicast link setup procedure.

The L2U2N remote UE sends a first RRC message (i.e., an rrcsetup request) using a specified PC5 relay RLC channel configuration for its connection establishment with the gNB via the L2U2N relay UE. If the L2U2N relay UE is not in rrc_connected, it needs to perform its own connection establishment upon receiving a message on the designated PC5 relay RLC channel. During the RRC connection setup procedure of the L2U2N relay UE, the gNB may configure the SRB0 relay Uu relay RLC channel to the U2N relay UE. The gNB responds to the L2U2N remote UE with an RRCSetup message. The RRCSetup message is sent to the L2U2N remote UE using the SRB0 relay channel on Uu and the designated PC5 relay RLC channel on PC 5.

And (2) filling x: during the RRC connection setup procedure of the L2U2N relay UE due to the remote UE, it is decided by the implementation of the L2U2N relay UE how to set the establishment cause value in the RRCSetup message.

The gNB and the L2U2N relay UE perform a relay channel setting procedure through Uu. According to the configuration from the gNB, the L2U2N relay/remote UE establishes a PC5 relay RLC channel for relay by SRB1 through PC5 towards the L2U2N remote/relay UE.

4. The rrcsetup complete message is sent to the gNB by the L2U2N remote UE via the L2U2N relay UE using the SRB1 relay channel on the PC5 and the SRB1 relay channel on Uu configured to the L2U2N relay UE. Subsequently, the L2U2N remote UE connects RRC via Uu.

The L2U2N remote UE and the gNB establish security following Uu procedure and forward security messages through the L2U2N relay UE.

The gNB sends an RRCReclonfiguration message via the L2U2N relay UE to the L2U2N remote UE to set SRB2/DRB for relay purposes. The L2U2N remote UE sends an rrcrecon configuration complete message to the gNB via the L2U2N relay UE as a response. In addition, the gNB may configure an additional Uu relay RLC channel between the gNB and the L2U2N relay UE, and a PC5 relay RLC channel between the L2U2N relay UE and the L2U2N remote UE for relaying traffic.

16.12.5.2 radio link failure

When the L2U2N remote UE connects to the gNB via the L2U2N relay UE, the L2U2N remote UE in rrc_connected suspends Uu RLM (as described in clause 9.2.7).

The L2U2N relay UE declares Uu Radio Link Failure (RLF) following the same criteria as described in clause 9.2.7. After declaring Uu RLF, the L2U2N relay UE takes the following actions on top of the actions described in clause 9.2.7:

the PC5-RRC message may be used to send an indication to the L2U2N remote UE to which it is connected, which may trigger RRC connection reestablishment for the L2U2N remote UE.

After detecting the PC5 RLF, the L2U2N remote UE may trigger connection re-establishment.

[…]

16.12.6 service continuity for L2U2N relay

16.12.6.0 general rule

The service continuity procedure is only applicable to mobility cases of path switching from indirect to direct path and from direct to indirect path when the L2U2N remote UE and the L2U2N relay UE belong to the same gNB.

[…]

16.12.6.2 switching from direct to indirect path

The gNB may select an L2U2N relay UE in any RRC state, namely RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED as the target L2U2N relay UE for direct to indirect path switching.

For service continuity of the L2U2N remote UE, in case the L2U2N remote UE switches to the indirect path via the L2U2N relay UE in rrc_connected, the following procedure is used:

Fig. 16.12.6.2-1 entitled "procedure for L2U2N remote UE to switch to indirect path" of 3gpp R2-2206232 is reproduced as fig. 19]

An L2U2N remote UE reports one or more candidate L2U2N relay UEs and Uu measurements after it measures/discovers the candidate L2U2N relay UEs:

-the L2U2N remote UE filters the appropriate L2U2N relay UEs according to relay selection criteria prior to reporting. The L2U2N remote UE should report only L2U2N relay UE candidates meeting higher layer criteria;

the report contains at least the L2U2N relay UE ID, the serving cell ID of the L2U2N relay UE, and the side link measurement information. The side link measurement may be the SL-RSRP of the candidate L2U2N relay UE and if SL-RSRP is not available, then SD-RSRP is used.

The gnb decides to handover the L2U2N remote UE to the target L2U2N relay UE. The gNB then sends an RRCRECONfigure message to the target L2U2N relay UE containing at least the local ID and L2 ID of the L2U2N remote UE, the Uu and PC5 relay RLC channel configuration for relay, and the bearer mapping configuration.

The gNB sends an RRCRECONfigure message to the L2U2N remote UE. The rrcrecon configuration message contains at least the L2U2N relay UE ID, the local ID of the remote UE, the PC5 relay RLC channel configuration for relaying traffic, and the associated end-to-end radio bearer. The L2U2N remote UE stops UP and CP transmissions on Uu after receiving the rrcrecon configuration message from the gNB.

And 4, the L2U 2N remote UE establishes PC5 RRC connection with the target L2U 2N relay UE.

The L2U 2N remote UE completes the path switch procedure by sending an rrcrecconfiguration complete message to the gNB via the L2U 2N relay UE.

6. The data path switches from a direct path to an indirect path between the L2U 2N remote UE and the gNB.

In the case where the selected L2U 2N relay UE for direct to indirect path switching is either rrc_idle or rrc_inactive, after receiving the path switching command, the L2U 2N remote UE establishes a PC5 link with the L2U 2N relay UE and sends an rrcrecnonfigurationcomplete message via the L2U 2N relay UE, which triggers the L2U 2N relay UE to enter the rrc_connected state. The procedure for L2U 2N remote UEs to switch to the indirect path in fig. 16.12.6.2-1 may also be applied if the selected L2U 2N relay UE for direct to indirect path switching is in rrc_idle or rrc_inactive, except that the rrcrecon configuration message is sent from the gNB to the L2U 2N relay UE after the L2U 2N relay UE enters the rrc_connected state.

3GPP TS 38.351 describes the following:

6.2.2 data PDU

Fig. 6.2.2-1 shows the format of an SRAP data PDU.

[3GPP TS 38.351V17.0.0, FIG. 6.2.2-1 entitled "SRAP data PDU Format" is reproduced as FIG. 20]

[…]

6.3.2UE ID

Length: 8 bits.

This field carries the local identity of the U2N remote UE.

6.3.3 bearer ID

Length: 5 bits.

This field carries the Uu radio bearer identity for the U2N remote UE.

6.3.4 data

Length: variable

This field carries SRAP SDUs (i.e., PDCP PDUs).

3GPP TS 23.700-33 introduces the following:

4.1 architecture requirements

The solution should be built on the 5G ProSe architecture principle as defined in TS 23.304[3] and the 5G system architecture principle as defined in TS 23.501[7], including flexibility and modularity for the newly introduced functionality.

To meet the regulatory level 1 general requirements in TS 22.278[5], TS 22.261[4] and TS 22.115[6], the system should:

support single NR PC 5-hop inter-UE relay for unicast.

-enhancing UE-to-network relay functionality to support:

-service continuity when switching between two indirect network communication paths for UE to network relay;

-service continuity when switching between a direct network communication path and an indirect network communication path for 5G ProSe layer 2UE to network relay, including inter-gNB indirect to direct and inter-gNB direct to indirect path switching;

multipath transmission using only one direct network communication path and only one indirect network communication path, e.g. for improved reliability or data rate;

Emergency services for remote UE through UE-to-network relay.

-supporting a path switch between a direct NR Uu communication path and a direct NR PC5 communication path;

note 1: the UE-to-network relay and inter-UE relay in this study include layer 3 and layer 2 relays unless explicitly stated.

And (2) injection: it is not intended to support session continuity (e.g., IP address reservation) during path switching between the direct NR Uu communication path and the direct NR PC5 communication path.

And (3) injection: for multipath transmission through layer 2 UE-to-network relay, the UE connects to the same gNB via layer 2 UE-to-network relay using one direct path and one indirect path.

And (4) injection: multipath transmission through layer 3 UEs to network relays cannot have RAN impact.

And (5) injection: the path switching between layer 2UE to network relay and layer 3UE to network relay cannot have RAN impact.

[…]

5.4 key issue #4: support for path switching between a direct network communication path and an indirect network communication path for layer 2UE to network relay with session continuity considerations

5.4.1 general description

This critical issue solves how to enhance 5GS to support path switching between direct and indirect network communication paths for layer 2 UE-to-network relay, including inter-gNB indirect-to-direct path switching and inter-gNB direct-to-indirect path switching.

When studying the above aspects, the following needs to be considered:

what the trigger and criteria for path switching are

How to select a direct network communication path or an indirect communication path for path switching.

How to perform path switching with session continuity considerations.

Note that: this key issue has a strong dependence on the RAN and requires input from the RAN WG to reach a conclusion.

[…]

6.23 solution #23: session continuity for path switching for L2U 2N relay

6.23.1 description

This solution solves the key problem 4 "support for path switching between a direct network communication path and an indirect network communication path for layer 2UE to network relay with session continuity considerations. This solution has been considered for Xn-based and N2-based HO procedures applied to inter-gcb indirect to direct and inter-gcb direct to indirect path switching.

In this solution, the source gNB determines whether to switch to a direct cell or an L2U 2N relay UE. If the source gNB determines to switch to the L2U 2N relay UE, the source gNB selects a target L2U 2N relay UE for the remote UE taking into account an authorized PLMN list for the L2U 2N remote UE.

The editor annotates: for inter-gNB cases, which one of the gnbs (source or target) selects the target relay UE or direct Uu routing depends on the RAN2 conclusion.

6.23.2.2 Xn-based inter-gNB direct to indirect path switching

Fig. 6.23.2.2-1 shows a procedure for indirect to direct path switching between Xn-based gnbs.

[ FIG. 6.23.2.2-1 entitled "procedure for direct to indirect Path switching between Xn-based gNBs" of 3GPP TS 23.700-33V0.3.0 is reproduced as FIG. 21]

1. The remote UE performs the measurement and reporting procedure, which is the same as step 1 in clause 16.X.6.2 in TS 38.300[15 ].

The gNB decides to handover the U2N remote UE to the target U2N relay UE. The gNB selects a target U2N relay UE that is included in an authorized PLMN list that is retrieved from the AMF to select the target U2N relay UE.

3. The source gNB transmits a handover request defined in TS 38.423[18], and at least a U2N relay UE ID, a U2N relay UE serving cell ID. The target gNB responds to the handover request acknowledgement defined in TS 38.413[19 ].

Steps 4 to 7 are performed as in steps 2 to 5 of clause 16.X.6.2 in TS 38.300[15 ].

If the selected U2N relay UE is in rrc_idle or rrc_inactive, step 7 will trigger the U2N relay UE to enter the rrc_connected state, in which case step 7 will then be performed before step 5.

8. The procedure is performed as in steps 1b to 9 in clause 4.9.1.2.2 in TS 23.502[8 ].

The editor annotates: the procedure has RAN dependencies. The procedure needs to be evaluated by the RAN WG.

[…]

6.23.2.4N 2-based inter-gNB direct to indirect path switching

Fig. 6.23.2.4-1 shows a procedure for indirect to direct path switching between N2-based gnbs.

[ FIG. 6.23.2.4-1 entitled "procedure for direct to indirect Path switching between N2-based gNBs" of 3GPP TS 23.700-33V0.3.0 is reproduced as FIG. 22]

3. The source gNB transmits the required handover defined in TS 38.413[19], and at least the U2N relay UE ID, the serving cell ID of the U2N relay UE.

4.T-AMF selection: the same as step 2 in clause 4.9.1.3.2 in TS 23.502[8 ].

5.S-AMF to T-AMF: the Namf Communication creation uecontext request is sent as specified in step 3 in clause 4.9.1.3.2 in TS 23.502[8], and at least the U2N relay UE ID, the serving cell ID of the U2N relay UE.

6. The procedure is performed as in steps 4 to 8 specified in clause 4.9.1.3.2 in TS 23.502[8 ].

7.T-AMF to T-RAN: the handover request is sent as specified in step 9 in clause 4.9.1.3.2 in TS 23.502[8], and at least the U2N relay UE ID, the serving cell ID of the U2N relay UE.

8. This step is performed as in step 2 of clause 16.X.6.1 in TS 38.300[15]

9. The procedure is performed as in steps 10 to 12 specified in clause 4.9.1.3.2 in TS 23.502[8 ].

10. The procedure is performed as in steps 1 to 3 specified in clause 4.9.1.3.3 in TS 23.502[8 ].

Steps 11 and 12 are performed as in steps 4 and 5 of clause 16.X.6.2 in TS 38.300[15 ].

If the selected U2N relay UE is in rrc_idle or rrc_inactive, step 7 will trigger the U2N relay UE to enter the rrc_connected state, in which case step 12 will then be performed before step 8.

13. The procedure is performed as in steps 5 to 15b in clause 4.9.1.3.3 in TS 23.502[8 ].

6.23.3 impact on services, entities and interfaces

The solution has an impact in the following entities:

gNB:

-the source gNB selects a target UE and sends target UE information to the AMF or the target gNB.

AMF:

-receiving target U2N relay UE information from the gNB and AMF.

-sending target U2N relay UE information to the gNB.

-sending the authorized PLMN list to the gNB.

3GPP RP-221262 describes the following:

the goal of this work item is to specify a solution for enhancing NR side link relay for V2X, public safety and business use cases.

1. A mechanism is specified to support single hop layer 2 and layer 3 inter-UE relay (i.e., source UE- > relay UE- > destination UE) for unicast RAN2, RAN3, RAN 4.

A. The common part for layer 2 and layer 3 relays is prioritized until RAN #98

i. Relay discovery and (re) selection [ RAN2, RAN4]

Signalling support for relay and remote UE authorization if SA2 concludes needed RAN3

B. Layer 2 relay specific part

inter-UE Relay Adaptation layer design [ RAN2]

Control plane procedure [ RAN2]

QoS handling under SA2 procedure (if needed) [ RAN2]

Note 1A: this work should consider the forward compatibility in the latter version for supporting more than one hop.

Note 1B: the remote UE connects to only a single relay UE at a given time for a given destination UE.

2. Mechanisms to enhance service continuity for single hop layer 2UE to network relay are specified for the following scenarios [ RAN2, RAN3]:

indirect to direct path switching between gNB (i.e. "remote UE < - > relay UE A < - > gNB X" to "remote UE < - > gNB Y")

Direct to indirect path switching between gNBs (i.e. "remote UE < - > gNB X" to "remote UE < - > relay UE A < - > gNB Y")

C.Indirect-to-Indirect path switching within gNB (i.e., "remote UE < - > Relay UE A < - > gNB X" to "remote UE < - > Relay UE B < - > gNB X")

Indirect to indirect path switching between gNB (i.e. "remote UE < - > relay UE A < - > gNB X" to "remote UE < - > relay UE B < - > gNB Y")

Note 2A: context D is supported by reusing solutions for other contexts without specific optimization.

3. The benefits and possible solutions of multipath support for enhancing reliability and throughput (e.g., by switching among multiple paths or simultaneously utilizing multiple paths) are studied in the following scenarios [ RAN2, RAN3]:

a.ue connects to the same gNB via 1) layer 2 UE-to-network relay or 2) via another UE (where the UE-UE connection is assumed to be ideal) using one direct path and one indirect path, where the solution for 1) will be reused for 2) without impeding the possibility of excluding an unnecessary part of the solution for the operation of 2).

Note 3A: research into benefits and possible solutions will be done in RAN #98, which will decide whether/how to start normative work.

Note 3B: the UE-to-network relay in scenario 1 re-uses the Rel-17 solution as a baseline.

Note 3C: support for layer 3UE to network relay in multipath scenario is assumed to have no RAN impact and the work and solution is subject to SA2 procedure.

4. At low priority, the gain is studied and, if needed, signaling between the gNB and relay UE in side link mode 2 is specified to help determine side link DRX configuration for remote UE in layer 2 UE-to-network side link relay operation [ RAN2]

5. Specifying RRM core requirements for relay discovery and (re) selection in inter-UE relay [ RAN4]

This work will not take into account the specific enhancements to side link relay support for the functionality specified in the Rel-18 side link enhancements. Rel-18 side link enhancements may be used in relay operations if they can be operated in relay without any special handling.

The NR side link in Rel-17 supports the features of UE-to-network (U2N) relay communications that enable cell coverage extension. The UE-to-network relay UE is in coverage and the remote UE may be out of coverage or in coverage. On the other hand, there are two types of UE-to-network relay communications, one is layer 3 UE-to-network relay and the other is layer 2 (L2) UE-to-network relay. For L2U 2N relay, an adaptation layer, referred to as a side link relay adaptation protocol (SRAP) layer, is placed over the Radio Link Control (RLC) sub-layer for the CP and UP at the Uu interface between the relay UE and the gNB. Uu Service Data Adaptation Protocol (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 each link (i.e., a PC5 layer 2 link or PC5 connection between the remote UE and the UE-to-network relay UE, and a Uu link or Uu RRC connection between the UE-to-network relay UE and the gNB). An adaptation layer placed at the PC5 interface allows one or more Uu Data Radio Bearers (DRBs) to be mapped to one SL/PC5 RLC channel by an N:1 mapping. In Rel-17, either a direct network communication path (i.e., the remote UE communicates directly with the gNB) or an indirect network communication path (i.e., the remote UE communicates with the gNB via the U2N relay UE) may be enabled for each time for the remote UE. In addition, rel-17 only supports direct-to-indirect path switching within the gNB for UE-to-NW relay communications. In other words, the remote UE does not change the serving gNB during the direct-to-indirect communication path handover.

As discussed in 3gpp TR 23.700-33 and RP-221262, rel-18 may support direct-to-indirect communication path switching between gnbs, i.e., a remote UE may communicate directly with a gNB and then communicate with another gNB via a relay UE. According to one exemplary embodiment, a step flow of direct-to-indirect communication path switching between gnbs is shown in fig. 23 (which shows a step flow for direct-to-indirect communication path switching between gnbs according to one exemplary embodiment), and each step is described below:

1. a UE capable of L2U 2N remote UE functionality may establish an RRC connection with a first gNB (i.e., source gNB) and communicate with the first gNB through a direct communication path.

2. The remote UE may initiate a relay UE discovery procedure for discovering one or more candidate relay UEs. The relay UE1 may transmit one or more relay discovery messages by using the first identity (e.g., source layer 2 ID) of the relay UE 1. The relay UE2 may send one or more relay discovery messages by using a second identity (e.g., source layer 2 ID) of the relay UE2. It is possible that the remote UE may discover relay UE1 and relay UE2 by receiving its relay discovery message. It is possible that the remote UE may be within the coverage of a serving cell handled/controlled by a first gNB, while relay UE1 and relay UE2 may be within the coverage of a serving cell handled/controlled by a second gNB (i.e., target gNB). The second gNB may belong to a PLMN, and the first gNB may also belong to the PLMN. The remote UE may report the identity of the remote UE (e.g., source layer 2 ID) to the first gNB via, for example, a sidlinkiueinfo nr.

3. The remote UE may be configured with a measurement configuration by the first gNB. The remote UE may send a measurement report to the first gNB. The measurement report may contain a first identity of relay UE1 and a second identity of relay UE 2. The measurement report may contain a first sidelink quality between the remote UE and the relay UE1 and a second sidelink quality between the remote UE and the relay UE 2. The measurement report may contain a first cell ID of relay UE1 and a second cell ID of relay UE 2. The first cell ID and the second cell ID may be the same if relay UE1 and relay UE2 are located or camped on the same serving cell. The measurement report may contain PLMN IDs to identify PLMNs and associated with relay UE1 and relay UE 2. The measurement report may contain a first list of target/candidate relay UEs found by the remote UE, and each entry of the first list for one target/candidate relay UE may contain one (layer 2) identity of the one target/candidate relay UE, one cell ID of the one target/candidate relay UE, one PLMN ID of the one target/candidate relay UE, and/or the like. Alternatively, the remote UE may report the above information to the first gNB by sending another RRC message instead of the measurement report.

4. In Rel-17, the gcb serving remote UE is responsible for selecting target relay UEs for implementing direct-to-indirect communication path handovers within the gcb. Based on the measurement report received from the remote UE, if the principles in Rel-17 are also followed, the first gNB may select a target relay UE for switching the remote UE from a direct communication path to an indirect communication path via the target relay UE. It is possible that the first gNB may select relay UE1 (because the first side link quality may be better than the second side link quality).

The maximum number of layer 2 links (or referred to as, for example, unicast links, PC5-S connections, PC5-RRC connections, PC5 connections, etc.) that can be established on the UE is limited (e.g., up to 8 layer 2 links are suggested according to [2 ]). On the other hand, a relay UE (at rrc_connected) serving any remote UE may report the identity (e.g., L2 ID) of the served remote UE to the gNB via, for example, a sidlinkiueinfo information nr. Thus, the gNB can know whether the relay UE can serve more remote UEs based on the SidelinkUEInformationNR reported by the relay UE. In other words, the first gNB may not be aware of the loading of relay UE1 and relay UE2, as these relay UEs are not served by the first gNB. The inter-gNB direct-to-indirect communication path handover involves a number of signaling exchanges between two gnbs (e.g., a handover prepare message sent by a first gNB and a handover command message sent by a second gNB for handover of a remote UE from the first gNB to the second gNB) and between the gNB and a remote/relay UE (e.g., RRC reconfiguration). If the first gNB selects relay UE1 but relay UE1 cannot serve more remote UEs, relay UE1 will refuse to establish a layer 2 link with the remote UE such that direct to indirect communication path switching cannot be completed. Failure of the direct to indirect communication path handover will trigger the remote UE to perform an RRC connection reestablishment procedure for selecting a new suitable cell or a new suitable relay UE. This will cause traffic delivery to be suspended and service to be interrupted.

Since the second gNB can be aware of the loading of relay UE1 and relay UE2, it would be better for the second gNB to select one target relay UE for direct-to-indirect communication path switching.

5. The first gNB (i.e., source gNB) may send first network signaling for preparing inter-gNB direct-to-indirect communication path handover to the second gNB (i.e., target gNB). The first network signaling may be a path switch and/or a switch ready message. The first network signaling may include an rrcrecon configuration (currently compiled by the remote UE) generated entirely by the first gNB. The first network signaling may indicate one or more target/candidate relay UEs that may belong to or be associated with the second gNB. The first network signaling may include a first identity of relay UE1 and a second identity of relay UE 2. The first network signaling may include a first cell ID of relay UE1 and a second cell ID of relay UE 2. The first network signaling may comprise a second list of target/candidate relay UEs belonging to or associated with the second gNB, and each entry of the second list may be associated with one target/candidate relay UE and may comprise one (layer 2) identity of the one target/candidate relay UE, one cell ID of the one target/candidate relay UE, one PLMN ID of the one target/candidate relay UE, and/or the like. The first network signaling may not contain information about any target/candidate relay UEs that do not belong to or are not associated with the second gNB. Thus, the size of the second list of target/candidate relay UEs may be equal to or smaller than the size of the first list of target/candidate relay UEs. Alternatively, the first list of target/candidate relay UEs may be included in the first network signaling.

6. Based on the first network signaling received from the first gNB, the second gNB may send second network signaling to the first gNB for the first gNB to initiate/effectuate/perform procedures for direct-to-indirect communication path switching between the gnbs. The second network signaling may be a path switch and/or a switch command message. The second network signaling may include a set of configurations generated by the second gNB (e.g., rrcrecnonfiguration to be compiled by the remote UE). The set of configurations may include Uu SDAP configuration (e.g., establishing a QoS flow to DRB mapping), uu DRB configuration (e.g., establishing one or more DRBs), SRAP configuration (e.g., for assigning a local UE ID of a remote UE and establishing a DRB to PC5 RLC relay channel mapping), PC5 RLC relay channel configuration (e.g., establishing one or more PC5 RLC relay channels), and/or the like. The configuration set or second network signaling may indicate a target relay UE (e.g., relay UE 2) selected by the second gNB. The configuration set or the second network signaling may contain a second identity of the relay UE 2.

7. The first gNB may send/forward a set of configurations contained in the second network signaling to the remote UE for direct-to-indirect communication path handover between the gnbs. This configuration set may be sent via a first RRC message (e.g., a first rrcrecon configuration). The first RRC message may also include a second identity of the relay UE 2.

The second gNB may send a second RRC message (e.g., a second rrcrecon configuration) to the relay UE2 for adding the remote UE for inter-gNB direct-to-indirect communication path handover. The second RRC message may contain the identity of the remote UE. The second RRC message may include an SRAP configuration (e.g., assigning a local UE ID of the remote UE and establishing a PC5RLC relay channel to Uu RLC relay channel mapping), a PC5RLC relay channel configuration (e.g., establishing one or more PC5RLC relay channels), a Uu RLC relay channel configuration (e.g., establishing one or more Uu RLC relay channels), and/or the like.

8. In response to receiving the first RRC message from the first gNB, the remote UE may initiate/perform establishment of a PC5 connection with the relay UE 2. After completing the establishment of the PC5 connection, the remote UE may send a third RRC message (e.g., rrcrecon configuration complete) corresponding to the first RRC message to the second gNB via the relay UE 2. The third RRC message may be included in an SRAP Protocol Data Unit (PDU). The header of the SRAP PDU may contain a field indicating the local identity/Identifier (ID) of the remote UE. The remote UE may then communicate with the second gNB via the relay UE2 over an indirect communication path.

Fig. 24 is a flow chart 2400 illustrating an exemplary method for a first network node. In step 2405, the first network node receives first information of a candidate relay User Equipment (UE) from a remote UE. In step 2410, the first network node transmits first information of the candidate relay UE or second information of the candidate relay UE to the second network node for the second network node to select the target relay UE, wherein the second information of the candidate relay UE is derived from the first information of the candidate relay UE.

In one embodiment, the first information of the candidate relay UEs may indicate one or more candidate relay UEs discovered by the remote UE, and each candidate relay UE indicated in the first information of the candidate relay UEs is associated with one layer 2ID, one cell ID, and/or one PLMN ID. The second information of the candidate relay UEs may indicate one or more candidate relay UEs associated with or belonging to the second network node. Each candidate relay UE indicated in the second information of the candidate relay UEs may be associated with one layer 2ID, one cell ID, and/or one PLMN ID.

In one embodiment, the first information of the candidate relay UE or the second information of the candidate relay UE may be transmitted from the first network node to the second network node via first network signaling, wherein one or more candidate relay UEs indicated in the first network signaling are associated with the same cell ID and/or the same PLMN ID. The first network signaling may be a handover request message.

In one embodiment, the first network node may receive second network signaling from a second network node, wherein the second network signaling indicates the target relay UE and includes a set of configurations for indirect communication between the remote UE and the second network node via the target relay UE. The second network signaling may be a handover request Acknowledgement (ACK) message.

Referring now to fig. 3 and 4, in one exemplary embodiment of a first network node, the first network node 300 comprises program code 312 stored in memory 310. CPU 308 may execute program code 312 to enable a first network node to: (i) Receiving first information of the candidate relay UE from the remote UE, and (ii) transmitting the first information of the candidate relay UE or second information of the candidate relay UE to the second network node for the second network node to select the target relay UE, wherein the second information of the candidate relay UE is derived from the first information of the candidate relay UE. Further, the CPU 308 may execute the program code 312 to perform all of the above-described acts and steps or other acts and steps described herein.

Fig. 25 is a flow chart 2500 illustrating an exemplary method for a second network node. In step 2505, the second network node receives second information of the candidate relay UE from the first network node. In step 2510, the second network node transmits second network signaling to the first network node, wherein the second network signaling indicates a target relay UE selected from the second information of the candidate relay UEs.

In one embodiment, the second information of the candidate relay UEs indicates one or more candidate relay UEs associated with or belonging to the second network node. Each candidate relay UE indicated in the second information of the candidate relay UEs may be associated with one layer 2ID, one cell ID, and/or one PLMN ID. The second information of the candidate relay UEs may be transmitted from the first network node to the second network node via the first network signaling, wherein one or more candidate relay UEs indicated in the first network signaling are associated with the same cell ID and/or the same PLMN ID. The first network signaling may be a handover request message.

In one embodiment, the second network signaling may include a set of configurations for indirect communication between the remote UE and the second network node via the target relay UE. The second network signaling may be a handover request ACK message.

Referring now to fig. 3 and 4, in one exemplary embodiment of the second network node, the second network node 300 comprises program code 312 stored in memory 310. CPU 308 may execute program code 312 to enable a second network node to: (i) Receiving second information of the candidate relay UE from the first network node, and (ii) transmitting second network signaling to the first network node, wherein the second network signaling indicates a target relay UE selected from the second information of the candidate relay UE. Further, the CPU 308 may execute the program code 312 to perform all of the above-described acts and steps or other acts and steps described herein.

Fig. 26 is a flow chart 2600 illustrating an exemplary method for a second network node. In step 2605, the second network node receives second information of the target relay UE from the first network node. In step 2610, the second network node transmits second network signaling to the first network node, wherein the second network signaling indicates a second relay UE indicated in second information of the target relay UE.

In one embodiment, a Radio Resource Control (RRC) connection is established between the first network node and the remote UE prior to receiving the second information of the target relay UE.

In one embodiment, the second information of the target relay UE may indicate one or more target relay UEs associated with or belonging to the second network node. Each target relay UE indicated in the second information of the target relay UE may be associated with one layer 2ID, one cell ID, and/or one PLMN ID. The second information of the target relay UE may indicate the first relay UE and the second relay UE. The second information of the target relay UE may include a layer 2ID of the first relay UE and a layer 2ID of the second relay UE. The second information of the target relay UE may be included in the first network signaling sent by the first network node.

In one embodiment, the second network signaling may include a set of configurations for indirect communication between the remote UE and the second network node via the second relay UE. The second network signaling may include a layer 2ID of the second relay UE.

In one embodiment, the set of configurations may include a Service Data Adaptation Protocol (SDAP) configuration, a Packet Data Convergence Protocol (PDCP) configuration, a side link relay adaptation protocol (SRAP) configuration, a PC5 Radio Link Control (RLC) channel configuration, and/or the like. The set of configurations or SRAP configuration may contain a local UE ID of the remote UE.

In one embodiment, the second network node may receive an RRC reconfiguration complete message from the remote UE via the second relay UE, wherein the RRC reconfiguration complete message may be included in the SRAP PDU and a header of the SRAP PDU may include a local UE ID of the remote UE.

In one embodiment, the first network node and/or the second network node may be a base station or a gNB. The first network signaling may be a handover preparation message or a handover request message. The second network signaling may be a handover command message or a handover request ACK message.

Referring now to fig. 3 and 4, in one exemplary embodiment of a second network node, a first network node 300 comprises program code 312 stored in a memory 310. CPU 308 may execute program code 312 to enable a second network node to: (i) Receiving second information of the target relay UE from the first network node, and (ii) transmitting second network signaling to the first network node, wherein the second network signaling indicates a second relay UE indicated in the second information of the target relay UE. Further, the CPU 308 may execute the program code 312 to perform all of the above-described acts and steps or other acts and steps described herein.

Fig. 27 is a flow chart 2700 illustrating an exemplary method for a first network node. In step 2715, the first network node receives first information of the target relay UE from the remote UE. In step 2710, the first network node transmits first information of the target relay UE or second information of the target relay UE to the second network node, wherein the second information of the target relay UE is derived from the first information of the target relay UE.

In one embodiment, the first network node may establish an RRC connection with the remote UE. The first information of the target relay UE may be included in an RRC message or measurement report transmitted by the remote UE. The first information of the target relay UE may indicate one or more target relay UEs discovered by the remote UE. Each target relay UE indicated in the first information of the target relay UE may be associated with one layer 2ID, one cell ID, and/or one PLMN ID. The first information of the target relay UE may indicate the first relay UE, the second relay UE, and the third relay UE.

In one embodiment, the first relay UE and the second relay UE may be associated with or served by a second network node. The third relay UE may be associated with or served by a third network node.

In one embodiment, the second information of the target relay UE may indicate one or more target relay UEs associated with or belonging to the second network node. Each target relay UE indicated in the second information of the target relay UE may be associated with one layer 2ID, one cell ID, and/or one PLMN ID. The second information of the target relay UE may indicate the first relay UE and the second relay UE. The second information of the target relay UE may be included in the first network signaling sent by the first network node.

In one embodiment, the first network node may receive second network signaling from a second network node, wherein the second network signaling indicates a second relay UE and includes a set of configurations for indirect communication between the remote UE and the second network node via the second relay UE. The second network signaling may include a layer 2ID of the second relay UE.

In one embodiment, the first network node may send an RRC reconfiguration message to the remote UE for direct to indirect communication path handover, wherein the RRC reconfiguration message indicates the second relay UE and contains the set of configurations. The RRC reconfiguration message may contain the layer 2ID of the second relay UE. The set of configurations may include an SDAP configuration, a PDCP configuration, an SRAP configuration, a PC5 RLC channel configuration, and/or the like.

In one embodiment, the first, second or third network node may be a base station or a gNB. The first network signaling may be a handover preparation message or a handover request message. The second network signaling may be a handover command message or a handover request ACK message.

Referring now to fig. 3 and 4, in one exemplary embodiment of a first network node, a second network node 300 comprises program code 312 stored in a memory 310. CPU 308 may execute program code 312 to enable a first network node to: (i) Receiving first information of the target relay UE from the remote UE, and (ii) transmitting the first information of the target relay UE or second information of the target relay UE to the second network node, wherein the second information of the target relay UE is derived from the first information of the target relay UE. Further, the CPU 308 may execute the program code 312 to perform all of the above-described acts and steps or other acts and steps described herein.

Various aspects of the disclosure have been described above. It should be understood that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented or such method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. As an example of some of the above concepts, in some aspects, parallel channels may be established based on pulse repetition frequencies. In some aspects, parallel channels may be established based on pulse positions or offsets. In some aspects, parallel channels may be established based on a hopping sequence. In some aspects, parallel channels may be established based on pulse repetition frequency, pulse position, or offset, and time hopping sequences.

Those of skill in the art would 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, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., digital implementations, analog implementations, or combinations of both, which may be designed using source coding or some other technique), various forms of program or design code incorporating instructions (which may be referred to herein as "software" or a "software module" for convenience), or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

Additionally, the various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by an integrated circuit ("IC"), an access terminal, or an access point. An IC may comprise 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, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute code or instructions that reside within the IC, outside the IC, or both. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

It should be understood that any particular order or hierarchy of steps in any disclosed process is an example of an example approach. It should be understood that the specific order or hierarchy of steps in the process may be rearranged based on design preferences while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The steps of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. Software modules (e.g., containing executable instructions and associated data) and other data may reside in data storage such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage medium known in the art. An example storage medium may be coupled to a machine, such as a computer/processor (which may be referred to herein as a "processor" for convenience), such that the processor can read information (e.g., code) from, and write information to, the storage medium. An example storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user equipment. In the alternative, the processor and the storage medium may reside as discrete components in a user device. Furthermore, in some aspects, any suitable computer program product may comprise a computer-readable medium comprising code relating to one or more of the aspects of the present disclosure. In some aspects, the computer program product may include packaging material.

While the invention has been described in connection with various aspects, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known and customary practice within the art to which the invention pertains.

Claims

1. A method for a first network node to support path switching, comprising:

the first network node receives first information of candidate relay user equipment from remote user equipment; and

the first network node sends the first information of the candidate relay user equipment or second information of the candidate relay user equipment to a second network node for the second network node to select a target relay user equipment, wherein the second information of the candidate relay user equipment is derived from the first information of the candidate relay user equipment.

2. The method of claim 1, wherein the first information of the candidate relay user devices indicates one or more candidate relay user devices discovered by the remote user device, and each candidate relay user device indicated in the first information of the candidate relay user devices is associated with a layer 2 identity, a cell identity, or a public land mobile network identity, and wherein the second information of the candidate relay user devices indicates one or more candidate relay user devices associated with or belonging to the second network node, and each candidate relay user device indicated in the second information of the candidate relay user devices is associated with a layer 2 identity, a cell identity, or a public land mobile network identity.

3. The method according to claim 1, wherein the first information of the candidate relay user equipment or the second information of the candidate relay user equipment is transmitted from the first network node to the second network node via first network signaling, wherein one or more candidate relay user equipments indicated in the first network signaling are associated with the same cell identity or the same public land mobile network identity, or wherein the first network signaling is a handover request message.

4. The method as recited in claim 1, further comprising:

the first network node receives second network signaling from the second network node, wherein the second network signaling indicates the target relay user equipment and includes a set of configurations for indirect communication between the remote user equipment and the second network node via the target relay user equipment, or wherein the second network signaling is a handover request acknowledgement message.

5. A first network node supporting path switching, comprising:

a control circuit;

a processor mounted in the control circuit; and

A memory mounted in the control circuit and operatively coupled to the processor;

wherein the processor is configured to execute program code stored in the memory to:

receiving first information of a candidate relay user equipment from a remote user equipment; and

and transmitting the first information of the candidate relay user equipment or the second information of the candidate relay user equipment to a second network node for the second network node to select a target relay user equipment, wherein the second information of the candidate relay user equipment is derived from the first information of the candidate relay user equipment.

6. The first network node of claim 5, wherein the first information of candidate relay user equipment indicates one or more candidate relay user equipment discovered by the remote user equipment, and each candidate relay user equipment indicated in the first information of candidate relay user equipment is associated with a layer 2 identity, a cell identity, or a public land mobile network identity, and wherein the second information of candidate relay user equipment indicates one or more candidate relay user equipment associated with or belonging to the second network node, and each candidate relay user equipment indicated in the second information of candidate relay user equipment is associated with a layer 2 identity, a cell identity, or a public land mobile network identity.

7. The first network node of claim 5, wherein the first information of the candidate relay user equipment or the second information of the candidate relay user equipment is transmitted from the first network node to the second network node via first network signaling, wherein one or more candidate relay user equipments indicated in the first network signaling are associated with a same cell identity or a same public land mobile network identity, or wherein the first network signaling is a handover request message.

8. The first network node of claim 5, wherein the processor is further configured to execute program code stored in the memory to:

a second network signaling is received from the second network node, wherein the second network signaling indicates the target relay user equipment and includes a set of configurations for indirect communication between the remote user equipment and the second network node via the target relay user equipment, or wherein the second network signaling is a handover request acknowledgement message.

9. A method for a second network node to support path switching, comprising:

The second network node receives second information of candidate relay user equipment from the first network node; and

the second network node transmits second network signaling to the first network node, wherein the second network signaling indicates a target relay user equipment selected from second information of the candidate relay user equipment.

10. The method according to claim 9, wherein the second information of the candidate relay user equipments indicates one or more candidate relay user equipments associated with or belonging to the second network node, and each candidate relay user equipment indicated in the second information of the candidate relay user equipments is associated with one layer 2 identity, one cell identity or one public land mobile network identity.

11. The method according to claim 9, wherein the second information of the candidate relay user equipment is transmitted from the first network node to the second network node via first network signaling, wherein one or more candidate relay user equipments indicated in the first network signaling are associated with the same cell identity or the same public land mobile network identity, or wherein the first network signaling is a handover request message.

12. The method according to claim 9, wherein the second network signaling comprises a set of configurations for indirect communication between a remote user equipment and the second network node via the target relay user equipment, and/or wherein the second network signaling is a handover request confirm message.

13. A second network node supporting path switching, comprising:

a control circuit;

a processor mounted in the control circuit; and

receiving second information of the candidate relay user equipment from the first network node; and

transmitting second network signaling to the first network node, wherein the second network signaling indicates a target relay user equipment selected from second information of the candidate relay user equipments.

14. The second network node according to claim 13, wherein the second information of the candidate relay user equipments indicates one or more candidate relay user equipments associated with or belonging to the second network node, and each candidate relay user equipment indicated in the second information of the candidate relay user equipments is associated with one layer 2 identity, one cell identity or one public land mobile network identity.

15. The second network node according to claim 13, wherein the second information of the candidate relay user equipment is transmitted from the first network node to the second network node via first network signaling, wherein one or more candidate relay user equipments indicated in the first network signaling are associated with the same cell identity or the same public land mobile network identity, or wherein the first network signaling is a handover request message.

16. The second network node according to claim 13, wherein the second network signaling comprises a set of configurations for indirect communication between a remote user equipment and the second network node via the target relay user equipment, or wherein the second network signaling is a handover request confirm message.