Patent Description:
In RAN#<NUM>, a new Study Item named "Study on NR V2X" was approved to study the enhancement to support advanced V2X (vehicle-to-anything or vehicular-to-anything) services beyond services supported in LTE (Long Term Evolution) Rel-<NUM> V2X. One of the objectives for NR (New Radio) V2X design is to study technical solutions for QoS (Quality of Service) management of the radio interface including both Uu (i.e., network-to-vehicle UE communication) and sidelink (i.e., vehicle UE-to-vehicle UE communication) used for V2X operations.

The advanced V2X services, e.g., advanced driving, extended sensors, platooning, captured in 3GPP Technical Report <NUM> V16. <NUM>, may require enhanced NR system and new NR Sidelink SL to meet the stringent requirements. Both communication interfaces, PCS and Uu, could be used to support advanced V2X use cases, taking into account radio conditions and the environment where the enhanced V2X (eV2X) scenario takes place. NR V2X systems may be expected to have a flexible design to support services with low latency and high reliability requirements, with higher system capacity and better coverage. The flexibility of the NR sidelink framework may allow easy extension of NR systems to support future development of further advanced V2X services and/or other services.

Support for V2V and V2X services has been introduced in LTE during Releases <NUM> and <NUM>, in order to expand the 3GPP platform to the automotive industry use cases. These work items defined an LTE Sidelink (SL) suitable for vehicular applications, and complementary enhancements to the cellular infrastructure.

3GPP V2X phase <NUM> in Rel-<NUM> introduces several new features in SL, including: carrier aggregation, high-order modulation, latency reduction, and feasibility study on both transmission diversity and short Transmission Time Interval TTI in SL. All these enhanced features in 3GPP V2X phase <NUM> may be primarily based on LTE and may require co-existing with Rel-<NUM> UE (User equipment) in the same resource pool.

The study defines at least the following two SL resource allocation modes:.

In Rel-<NUM> V2X, the Mobility Management Entity (MME) indicates the UE authorization status to the eNB. When the UE requests resources from the eNB, the eNB checks the UE's authorization information according to the V2X service authorized Information Element IE in the UE context obtained from the MME. If the UE is authorized, the eNB configures the corresponding resource for the UE. Similarly, for NR V2X, the gNB can obtain V2X UE-related authorization information from the Authentication Management Function AMF and/or via Xn interface and verify whether the UE is authorized when the UE requests NR sidelink resources.

MR-DC (Multi-Radio Dual Connectivity) operation scenarios for V2X considered in the study are illustrated in <FIG> as discussed below:.

3GPP discussion paper R3-<NUM> "Considerations on the issues for MR-DC based NR V2X" from LG Electronics Inc. investigates potential issues of some MR-DC based scenarios based on RAN1 and RAN2's progress and suggests for RAN3 to investigate the following issues for supporting MR-DC based NR V2X: For mode <NUM>, how the other RAT's resource pool is notified/configured to MN if MN is in charge of configuration to UE; and for mode <NUM>, how the MN schedules the other RAT's sidelink resources to UE and whether the SN should be involved.

3GPP discussion paper R2-<NUM> "Cross-RAT sidelink configuration in MR-DC" from LG Electronics Inc. discusses how RAN provides cross-RAT resource allocation and configuration in MR-DC and proposes to agree the following proposals: While MR-DC is configured, UE receives V2X specific SIB at PCell only from MN RAT to acquire NR/LTE sidelink specific configuration e.g. resource pool configuration; only MN can provide NR/LTE sidelink configuration (e.g. resource pool) to a UE configured with MR-DC via RRC dedicated signaling as in LTE DC; NR/LTE sidelink configuration can be provided to a UE configured with MR-DC via a direct or split SRB1; and if RAN2 agrees that UE can send an uplink RRC message carrying sidelink information to RAN, the uplink RRC message is carried via SRB1 only which may be a direct or split bearer.

3GPP standard <NUM> "NG-RAN; Xn application protocol (XnAP), V15. <NUM> specifies the radio network layer signalling procedures of the control plane between NG-RAN nodes in NG-RAN. XnAP supports the functions of the Xn interface by signalling procedures defined in this document.

3GPP discussion paper R3-<NUM> "Resource coordination in MR-DC for NR V2X sidelink communication" from Ericsson proposes to enable NR V2X sidelink (SL) resource coordination between NG-RAN nodes in MR-DC by leveraging UE-associated signaling between Master Node (MN) and Secondary Node (SN). The signaling includes messages from MN to SN, and vice versa, carrying the intended SL resource allocation for the V2X UE as well as the V2X Authorization.

<CIT> discloses a systems and methods to configure sidelink resources in a dual connectivity operation. In some aspect, a method comprising: transmitting, from a user equipment (UE), a first message to a first evolved Node B (eNB), wherein the first message indicates a request to establish a sidelink communication; receiving, at the UE, a second message from the first eNB, wherein the second message indicates a frequency that is used by a secondary evolved Node B (SeNB); transmitting, from the UE, a measurement result to the first eNB; and receiving, at the UE, sidelink configuration information from the first eNB, wherein the sidelink configuration information indicates sidelink resources managed by the secondary eNB.

<CIT> discloses a method for operating a radio network node of a radio communications network. A wireless device in a cell of a first radio network node may be identified as having at least one transmission-specific property that affects a sensitivity to interference. Data identifying the at least one transmission-specific property corresponding to the wireless device in the cell of the first radio network node is sent from the first radio network node to a second radio network node that includes at least a portion of an overlapping cell relative to the first radio network node. Related methods in radio network nodes and apparatuses are disclosed.

Notwithstanding SL/V2X communications discussed above, there continues to exist demand for improved sidelink communications (e.g., between vehicles).

According to some embodiments, methods may be provided to operate a master radio access network RAN node in a wireless communication network. In such methods, a secondary RAN node addition or modification request message to request preparation or modification of resources for dual connectivity communication for a wireless terminal is transmitted from the master RAN node to a secondary RAN node, wherein resource coordination information is included as an information element of the secondary RAN node addition or modification request message and defines at least one communication resource that is available for a wireless terminal to use for sidelink communication.

According to some other embodiments, methods may be provided to operate a secondary radio access network RAN node in a wireless communication network. In such methods, a secondary RAN node addition or modification request message to request preparation or modification of resources for dual connectivity communication for a wireless terminal is received at the second RAN node, wherein resource coordination information is included as an information element of the secondary RAN node addition or modification request message and defines at least one communication resource that is available for a wireless terminal to use for sidelink communication.

Coordination of V2X sidelink resource may thus be provided for dual connectivity in cross-RAT (Radio Access Technology) scenarios by leveraging UE associated signaling. Accordingly, exchange of cell level resource pools between RAN nodes may be reduced thereby increasing efficiency of network signaling resource usage and/or reducing conflict between scheduling allocations from/between RAN nodes.

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in a constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings:.

<FIG> is a block diagram illustrating elements of a wireless terminal UE <NUM> (also referred to as a wireless communication device, a wireless device, a wireless communication terminal, user equipment, UE, a user equipment node/terminal/device, etc.) configured to provide SL/V2X sidelink communication according to embodiments of inventive concepts. A sidelink communication is a communication mechanism of user data and/or control data between devices (e.g. vehicles or UEs) without going through a base station (e.g. e eNB or gNB) or without being controlled by a base station. As shown, wireless terminal UE <NUM> may include a transceiver circuit <NUM> (also referred to as a transceiver) including a transmitter and a receiver configured to provide uplink and downlink radio communications with a base station of a radio access network, and to provide SL/V2X sidelink communications (e.g., V2V and/or V2P communications) directly with other V2X wireless terminals. Wireless terminal UE <NUM> may also include a processor circuit <NUM> (also referred to as a processor) coupled to the transceiver circuit, and a memory circuit <NUM> (also referred to as memory) coupled to the processor circuit. The memory circuit <NUM> may include computer readable program code that when executed by the processor circuit <NUM> causes the processor circuit to perform operations according to embodiments disclosed herein. According to other embodiments, processor circuit <NUM> may be defined to include memory so that a separate memory circuit is not required. Wireless terminal UE may also include an interface (such as a user interface) coupled with processor <NUM>, and/or wireless communication device UE may be incorporated in a vehicle.

As discussed herein, operations of wireless terminal UE <NUM> may be performed by processor <NUM> and/or transceiver <NUM>. For example, processor <NUM> may control transceiver <NUM> to transmit communications through transceiver <NUM> over a radio interface to another UE and/or to receive communications through transceiver <NUM> from another UE over a radio interface. In addition, processor <NUM> may control transceiver <NUM> to receive communications through transceiver <NUM> from Radio Access Network node (e.g., a base station, an eNodeB/eNB gNodeB/gNB, etc.). Moreover, modules may be stored in memory <NUM>, and these modules may provide instructions so that when instructions of a module are executed by processor <NUM>, processor <NUM> performs respective operations (e.g., operations discussed below with respect to UEs).

<FIG> is a block diagram illustrating elements of a radio access network (RAN) node <NUM> (also referred to as a network node, base station, eNB, eNodeB, gNB, gNodeB, core network entity node, etc.) of a wireless communication network configured to provide cellular communication according to embodiments of inventive concepts. As shown, the RAN node <NUM> may include communication interface with a transceiver circuit <NUM> and/or a network interface circuit <NUM>. A radio access network RAN node, for example, may include transceiver circuit <NUM> for wireless communication with wireless terminals UEs and network interface circuit <NUM> for communication with other RAN nodes and/or with core network entity nodes. A core network entity node may be provided as shown in <FIG> but omitting the transceiver circuit, and communications between such a core network entity node and a wireless terminal UE may be provided through the network interface circuit and a RAN node. Transceiver circuit <NUM> (also referred to as a transceiver) may include a transmitter and a receiver configured to provide uplink and downlink radio communications with wireless terminals UEs. The RAN node may include a network interface circuit <NUM> (also referred to as a network interface) configured to provide communications with other nodes (e.g., with other RAN nodes and/or core network entity nodes) of the RAN and/or core network. The RAN node may also include a processor circuit <NUM> (also referred to as a processor) coupled to the transceiver circuit, and a memory circuit <NUM> (also referred to as memory) coupled to the processor circuit. The memory circuit <NUM> may include computer readable program code that when executed by the processor circuit <NUM> causes the processor circuit to perform operations according to embodiments disclosed herein. According to other embodiments, processor circuit <NUM> may be defined to include memory so that a separate memory circuit is not required.

As discussed herein, operations of the RAN node may be performed by processor <NUM>, network interface <NUM>, and/or transceiver <NUM>. For example, processor <NUM> may control transceiver <NUM> to transmit communications through transceiver <NUM> over a radio interface to one or more wireless terminals UEs and/or to receive communications through transceiver <NUM> from one or more wireless terminals UEs over a radio interface. Similarly, processor <NUM> may control network interface <NUM> to transmit communications through network interface <NUM> to one or more other RAN nodes and/or to receive communications through network interface from one or more other RAN nodes. Moreover, modules may be stored in memory <NUM>, and these modules may provide instructions so that when instructions of a module are executed by processor <NUM>, processor <NUM> performs respective operations (e.g., operations discussed below with respect to Example Embodiments <NUM>-<NUM>).

In Rel-<NUM>, X2AP signaling for E-UTRA-NR UE-level resource coordination was introduced in 3GPP TS <NUM> V <NUM>. A motivation for E-UTRA-NR UE-level resource coordination is to reduce/avoid that a UE in an EN-DC scenario is configured with an E-UTRA-NR carrier frequency combination that would lead to a 1TX and/or harmonic interference problems. The F1AP specification 3GPP TS <NUM> V15. <NUM> defines containers for the transfer of E-UTRA -NR UE-level resource coordination information to the gNB-DU. The XnAP signaling is yet to be defined.

The E-UTRA-NR UE-level resource coordination signaling messages are exchanged between an eNB and gNB. The messages contain a bitmap that corresponds to the time-frequency resource grid, where each bit in the bitmap corresponds to one E-UTRA PRB (Physical Resource Block) pair. The bit value ' <NUM>' in the bitmap means that the corresponding PRB pair is intended for UE scheduling (for the UE for which the resources are being coordinated) by the sending node. The bitmap is constructed with respect to the E-UTRA resource grid, which means that the NR node sending the coordination message must translate the NR resource allocation into the E-UTRA resource grid. For example, two adjacent NR PRB pairs for <NUM>-kHz NR subcarrier spacing will correspond to four bits in the E-UTRA resource bitmap, because E-UTRA subcarrier spacing is <NUM>.

One thing that may be needed for the NR V2X operation is the support for V2X resource coordination in MR-DC scenarios to provide resource coordination for cross-RAT V2X sidelink communication. If, for example, there is no support for mode-<NUM> scheduling in another RAT, there may be a need to support this by MR-DC solutions, e.g. option <NUM>, <NUM> and <NUM> (discussed with respect to <FIG>), where each node performs scheduling within its own RAT for the sidelink resources. In this case, each NG-RAN node may handle only sidelink transmission of the same RAT as shown in <FIG> (Option <NUM>) and in <FIG> (options <NUM> and <NUM>). According to some embodiments, signaling solutions may enable NR V2X UE cross-RAT sidelink resource coordination, which may be included in 3GPP TR <NUM> v1.

In Rel-<NUM>/<NUM> LTE V2X, it was assumed that eNB could obtain the inter-cell sidelink resource pool configuration from OAM (Operations, Administration & Maintenance). However, OAM generally only manages the gNBs of one PLMN (Public Land Mobile Network) and may not be aware of the sidelink resource configuration of the neighboring gNB of another PLMN. Furthermore, it is possible that the two nodes in MR-DC scenario are managed by different OAM systems, as well as the scenario where a gNB-DU and gNB-CU of the same gNB are managed by different OAM systems. Consequently, the OAM-based solution may not be suitable for supporting the NR V2X SL operation.

Accordingly, the Master Node (MN) and the Secondary Node (SN) may need to provide V2X scheduling sidelink information to each other related to NR mode-<NUM> in all MR-DC scenarios, via proper inter-node signaling. According to some embodiments, it is proposed that MR-DC support of V2X cross-RAT provisioning should be enabled by proper inter-node signaling between MN and SN, and vice-versa. According to some other embodiments, it is proposed that the X2/Xn signalling should contain the intended resource allocation for the V2X UE and additional V2X-specific information. Coordination of V2X sidelink resources for MR-DC in mode-<NUM> may be enabled by leveraging existing mechanisms for UE-associated signaling between MN and SN introduced in TS <NUM>, for example, the MeNB resource Coordination information IE defined in clause <NUM>. <NUM> and the Mobility V2X Services Authorized IE, defined in clause <NUM>. <NUM>, of TS <NUM>, and the V2X SgNB resource Coordination information IE, which is the SgNB resource Coordination information IE defined in clause <NUM>. <NUM> of TS <NUM>. According to some other embodiments, it is proposed to add the TP in TR <NUM> for MR-DC cross-RAT sidelink resource coordination. Resource coordination in MR-DC is also discussed in R3-<NUM>.

Some embodiments of the present disclosure propose signaling between MN (master RAN node) and SN (Secondary RAN node) to enable V2X sidelink communication. The signaling may include messages from MN to SN and vice versa. The messages may contain the intended resource allocation for the V2X UE and additional V2X-specific information.

Some embodiments of the present disclosure may enable coordination of V2X sidelink resources for dual connectivity DC by leveraging UE-associated signaling.

Some embodiments may also reduce/avoid the exchange of cell-level V2X resource pools between the MN and SN nodes over non-UE-associated signaling. Such cell-level exchange, without additional knowledge of the neighbor cell deployment and served V2X UE positions, might result in a suboptimal radio resource allocation at the receiving node and/or in a waste of network signaling resources. In fact, cell-level resources (which are provided via broadcast signaling) are typically configured in a static way, irrespective of the amount of UEs which are interested in SL operations in such cell. On the other hand, UE-dedicated resource allocation (which can be achieved either via mode-<NUM> or mode-<NUM> configuration) may be dimensioned such that UE traffic requirements are fulfilled, and it may be desirable that such resources are not interfered by other concurrent transmissions in neighboring cells. In particular, in the case of MR-DC configuration, in which a UE can receive scheduling allocation from both MN and SN, it may be important that some level of coordination is provided/guaranteed in order to reduce/avoid conflicts between the scheduling allocations from the MN and SN.

Some embodiments of inventive concepts are presented on a non-limiting example of EN-DC and the corresponding X2AP signaling, whereas embodiments of the present disclosure may also apply to any other type of dual connectivity, e.g. NGEN-DC, NE-DC etc. The following embodiments address MN and SN operations where the MN and the SN can be any of the eNB/gNB nodes operating in any of the above possible MR-DC configurations.

The sidelink resource coordination may be executed as follows:.

A detailed description of some embodiments is presented on a non-limiting example of EN-DC and the corresponding X2AP signaling, whereas proposed embodiments can also be applied to any other type of dual connectivity, e.g. NGEN-DC, NE-DC etc..

Non-limiting examples of adding information of some embodiments into existing X2AP signaling, including signaling charts, are illustrated in the message diagrams of <FIG>, and in the messages of <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG> (including information elements V2X Services Authorized and/or V2X MeNB Resource Coordination Information, and/or V2X SgNB Resource Coordination Information). Some embodiments of inventive concepts may also be applied/added to existing XnAP and/or F1AP signaling in a similar way.

Signaling Charts, Messages and Information elements for Dual Connectivity procedures are discussed below with respect to <FIG>.

<FIG> illustrates communication of the SgNB Addition Request and SgNB Addition Request Acknowledge messages between master and secondary nodes (MN and SN) according to some embodiments of inventive concepts. These messages and elements thereof are discussed below with respect to <FIG> and <FIG>.

<FIG> illustrates communication of the SgNB Modification Request and SgNB Modification Request Acknowledge messages between master and secondary nodes (MN and SN) according to some embodiments of inventive concepts. These messages and elements thereof are discussed below with respect to <FIG> and <FIG>.

<FIG> illustrates communication of the SgNB Modification Required and SgNB Modification Confirm messages between master and secondary nodes (MN and SN) according to some embodiments of inventive concepts. These messages and elements thereof are discussed below with respect to <FIG> and <FIG>.

The SGNB ADDITION REQUEST message may be sent by the MeNB to the en-gNB to request the preparation of resources for EN-DC operation for a specific UE
Direction: MeNB → en-gNB.

<FIG> is an abbreviated table illustrating elements of the SGNB Addition Request message according to some embodiments of inventive concepts.

The SGNB ADDITION REQUEST ACKNOWLEDGE message may be sent by the en-gNB to confirm the MeNB about the SgNB addition preparation. Direction: en-gNB → MeNB.

<FIG> is an abbreviated table illustrating elements of the SGNB Addition Request Acknowledge message according to some embodiments of inventive concepts.

The SGNB MODIFICATION REQUEST message may be sent by the MeNB to the en-gNB to request the preparation to modify en-gNB resources for a specific UE, to query for the current SCG configuration, or to provide the S-RLF-related information to the en-gNB. Direction: MeNB → en-gNB.

<FIG> is an abbreviated table illustrating elements of the SGNB Modification Request message according to some embodiments of inventive concepts.

The SGNB MODIFICATION REQUEST ACKNOWLEDGE message may be sent by the en-gNB to confirm the MeNB's request to modify the en-gNB resources for a specific UE. Direction: en-gNB → MeNB.

<FIG> is an abbreviated table illustrating elements of the SGNB Modification Request Acknowledge message according to some embodiments of inventive concepts.

The SGNB MODIFICATION REQUIRED message may be sent by the en-gNB to the MeNB to request the modification of en-gNB resources for a specific UE. Direction: en-gNB → MeNB.

<FIG> is an abbreviated table illustrating elements of the SGNB Modification Required message according to some embodiments of inventive concepts.

The SGNB MODIFICATION CONFIRM message may be sent by the MeNB to inform the en-gNB about the successful modification. Direction: MeNB → en-gNB.

<FIG> is an abbreviated table illustrating elements of the SGNB Modification Confirm message according to some embodiments of inventive concepts.

The core network CN and higher radio access network RAN functions may be implemented as software functions running in a virtualized environment according to some embodiments of inventive concepts.

According to some embodiments of inventive concepts, signaling may be provided to enable New Radio NR V2X UE cross-RAT sidelink resource coordination.

Operations of RAN nodes <NUM> will now be discussed with reference to the flow charts of <FIG> and <FIG> according to some embodiments of inventive concepts. For example, modules may be stored in memory <NUM> of <FIG>, and these modules may provide instructions so that when the instructions of a module are executed by a respective RAN node processor <NUM>, processor <NUM> performs respective operations of the respective flow chart.

<FIG> illustrates operations of a master RAN node MN initiating transmission of resource coordination information to a secondary RAN node SN, with the master and secondary RAN nodes MN and SN together providing dual connectivity, DC, communication for a wireless terminal. <FIG> illustrates corresponding operations of the secondary RAN node SN. Each of the master RAN node MN of <FIG> and the secondary RAN node SN of <FIG> may be provided according to the structure illustrated in <FIG>. Moreover, the master and secondary RAN nodes MN and SN may be physically separate RAN nodes operating according to different Radio Access Technologies, RATs.

At block <NUM> of <FIG>, processor <NUM> of the master RAN node MN allocates at least one communication resource that is available for the wireless terminal to use for sidelink SL communication. For example, the SL communication may be V2X communication.

At block <NUM> of <FIG>, processor <NUM> of the master RAN node MN transmits first resource coordination information through network interface <NUM> to a secondary RAN node SN, wherein the first resource coordination information defines the at least one communication resource that is available for the wireless terminal to use for sidelink communication. The first resource coordination information is transmitted as an information element of a secondary RAN node SN addition request message (e.g., a SgnB Addition Request message as discussed above with respect to <FIG> and <FIG>) or a secondary RAN node SN modification request message (e.g., a SgnB Modification Request message as discussed above with respect to <FIG> and <FIG>). In addition, the resource coordination information may be transmitted with an indication of a priority associated with sidelink communications for the wireless terminal using the at least one communication resource.

At block <NUM> of <FIG>, processor <NUM> of the master RAN node MN may receive (through network interface <NUM>) second resource coordination information from the secondary RAN node SN, wherein the second resource coordination information is responsive to the first resource coordination information. According to some embodiments, the second resource coordination information may include an acknowledgement of the first resource coordination information, and/or the second resource coordination information may define at least one communication resource that will be used by the secondary RAN node SN to schedule communications for the wireless terminal. For example, the second resource coordination information may be received as an information element of a secondary RAN node SN addition request acknowledge message (e.g., a SgnB Additional Request Acknowledge message as discussed above with respect to <FIG> and <FIG>) or a secondary RAN node SN modification request acknowledge message (e.g., a SgnB Modification Request Acknowledge message as discussed above with respect to <FIG> and <FIG>).

At block <NUM> of <FIG>, processor <NUM> of the master RAN node MN may transmit an indication of the at least one resource that is available for the wireless terminal to use for SL communication through transceiver <NUM> to the wireless terminal.

Various operations from the flow chart of <FIG> may be optional with respect to some embodiments of RAN nodes and related methods. Regarding methods of example embodiment <NUM> (set forth below), for example, operations of blocks <NUM>, <NUM>, and <NUM> of <FIG> may be optional.

At block <NUM> of <FIG>, processor <NUM> of the secondary RAN node SN receives (through network interface <NUM>) the first resource coordination information from the master RAN node MN (e.g., from block <NUM> of <FIG>), wherein the first resource coordination information defines at least one communication resource that is available for the wireless terminal to use for sidelink communication. The first resource coordination information is received as an information element of a secondary RAN node SN addition request message (e.g., a SgnB Addition Request message as discussed above with respect to <FIG> and <FIG>) or a secondary RAN node SN modification request message (e.g., a SgnB Modification Request message as discussed above with respect to <FIG> and <FIG>). In addition, the resource coordination information may be received with an indication of a priority associated with sidelink communications for the wireless terminal using the at least one communication resource.

At block <NUM> of <FIG>, processor <NUM> of the secondary RAN node SN may schedule uplink, downlink, and/or sidelink communications for the wireless terminal based on the first resource coordination information received from the master RAN node MN. If the first resource coordination information is received with an indication of a priority associated with sidelink communications for the wireless terminal using the at least one communication resource, scheduling may be further based on the indication of priority.

At block <NUM> of <FIG>, processor <NUM> of the secondary RAN node SN may transmit the second resource coordination information from through network interface <NUM> to the master RAN node MN (e.g., to block <NUM> of <FIG>), wherein the second resource coordination information is responsive to the first resource coordination information. According to some embodiments, the second resource coordination information may include an acknowledgement of the first resource coordination information, and/or the second resource coordination information may define at least one communication resource that will be used by the secondary RAN node SN to schedule communications for the wireless terminal. For example, the second resource coordination information may be transmitted as an information element of a secondary RAN node SN addition request acknowledge message (e.g., a SgnB Additional Request Acknowledge message as discussed above with respect to <FIG> and <FIG>) or a secondary RAN node SN modification request acknowledge message (e.g., a SgnB Modification Request Acknowledge message as discussed above with respect to <FIG> and <FIG>).

Various operations from the flow chart of <FIG> may be optional with respect to some embodiments of RAN nodes and related methods. Regarding methods of example embodiment <NUM> (set forth below), for example, operations of blocks <NUM> and <NUM> of <FIG> may be optional.

<FIG> illustrates embodiments which are not according to the claimed invention and are presented for illustration purposes only.

<FIG> illustrates operations of a secondary RAN node SN initiating transmission of resource coordination information to a master RAN node MN, and <FIG> illustrates corresponding operations of the master RAN node MN. Each of the secondary RAN node SN of <FIG> and the master RAN node MN of <FIG> may be provided according to the structure illustrated in <FIG>. Moreover, the secondary and master RAN nodes SN and MN may be physically separate RAN nodes operating according to different Radio Access Technologies, RATs.

At block <NUM> in <FIG>, secondary RAN node SN processor <NUM> may allocate at least one communication resource that is available for a wireless terminal to use for sidelink SL communication.

At block <NUM> in <FIG>, secondary RAN node SN processor <NUM> may transmit resource coordination information through network interface <NUM> to the master RAN node MN, wherein the resource coordination information defines at least one communication resource that is available for a wireless terminal to use for sidelink communication. For example, the resource coordination information may be transmitted as an information element of a secondary RAN node SN modification required message (e.g., a SgnB Modification Required message discussed above with respect to <FIG> and <FIG>).

At block <NUM> in <FIG>, secondary RAN node SN processor <NUM> may receive a confirmation (through network interface <NUM>) from the master RAN node MN with respect to the resource coordination information. For example, the confirmation may be received as an information element of a secondary RAN node SN modification confirm message (e.g., a SgnB Modification Confirm message as discussed above with respect to <FIG> and <FIG>).

At block <NUM> in <FIG>, secondary RAN node SN processor <NUM> may transmit an indication of the at least one resource that is available for the wireless terminal to use for SL communication through transceiver <NUM> to the wireless terminal responsive to receiving the confirmation.

At block <NUM> in <FIG>, master RAN node MN processor <NUM> may receive the resource coordination information (from block <NUM> of <FIG>) through network interface <NUM> from the secondary RAN node SN, wherein the resource coordination information defines at least one communication resource that is available for a wireless terminal to use for sidelink communication. As discussed above with respect to block <NUM>, the resource coordination information may be received as an information element of a secondary RAN node SN modification required message (e.g., a SgnB Modification Required message discussed above with respect to <FIG> and <FIG>).

At block <NUM> in <FIG>, master RAN node MN processor <NUM> may transmit a confirmation through network interface <NUM> to the secondary RAN node SN with respect to the resource coordination information. As discussed above with respect to block <NUM>, the confirmation may be transmitted as an information element of a secondary RAN node SN modification confirm message (e.g., a SgnB Modification Confirm message as discussed above with respect to <FIG> and <FIG>).

Claim 1:
A method of operating a master radio access network, RAN, node in a wireless communication network, the method comprising:
transmitting (<NUM>, <NUM>), to a secondary RAN node, a secondary RAN node addition or modification request message to request preparation or modification of resources for dual connectivity communication for a wireless terminal,
wherein resource coordination information is included as an information element of the secondary RAN node addition or modification request message and defines at least one communication resource that is available for a wireless terminal to use for sidelink communication.