Methods for pre-emptive buffer status reporting for wireless access backhauling

Abstract

A wireless access backhaul (WAB) node determines that data will have to be transmitted over a backhaul connection based on (i) a buffer status report (BSR) received from a first network node (e.g. UE)

Description

BACKGROUND Field

[0001] Certain examples of the present disclosure provide various techniques relating to preemptive buffer status report (BSR), in particular in a network incorporating wireless access backhaul (WAB), for example within 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) and NR-based networks. Description of the Related Art Wireless Access Backhaul

[0002] Wireless access backhaul (WAB) is the name for a new type of node that is being introduced to 3GPP. The purpose of the WAB is to provide support for a base station, which acts as a relay, where the backhauling is provided over a wireless link, with less standard impacts compared to other solutions. For instance, the backhaul link performs backhauling of the interfaces from a gNB to the core network, i.e the CP interface between gNB and AMF and other nodes, as well as UP interface between gNB and UPF. This is as opposed to IAB, where the “relay” is only the gNB-DU and the backhauling link carries traffic via gNB-DU and gNB-CU. The WAB node is envisioned to be capable of mobility, to serve use cases such as 5G access onboard aircraft, cruiseships and other vehicles in remote areas. The WAB may also be deployed in emergency areas or during public safety cases.

[0003] The WAB node may be seen in FIG. 1. FIG. 1 illustrates the WAB node and how it relates to UEs, the backhaul gNB, backhaul 5GC, neighbouring gNBs and the 5GC of a UE.

[0004] The 3GPP Rel-19 Study Item “Study on additional topological enhancements for NR” [RP-241264] had the following objectives related to WAB: Study the support of WAB including [RAN3, RAN2]: Study the architecture and protocol stack of supporting a gNB with MT function providing PDU session backhaul. Study impact of WAB mobility within an existing RAN (e.g., inter-gNB neighbour relations). Identify necessary inter-gNB- and gNB-to-CN signalling to address the support of WAB. Study signalling enhancements on resource multiplexing for WAB. NOTE 1: No impact on the UE. NOTE 2: Coordination with other WGs (e.g. SA2) when needed.

[0005] The results of the study was captured in TR 38.799 “Study on topological enhancements for NR”.

[0006] The 3GPP Rel-19 Work Item “Additional topological enhancements for NR” [RP-242395] have the following objectives related to WAB: Specifications for the support of WAB including [RAN3]: Support of a WAB-node including a WAB-gNB and a WAB-MT. Support of backhauling of the WAB-gNB’s NG, Xn and OAM traffic over the WAB-MT ’s PDU session(s). Support ofXn interface(s) by the WAB-gNB with the WAB-MTs serving BH RAN node and with other surrounding gNBs, including how to avoid setting up Xn between WAB-gNBs. Defining the behaviour of WAB-node in case the authorization status of WAB-MT and / or WAB-gNB changes. Network integration procedures for WAB nodes. Handling of WAB-gNB’s traffic (including Xn, NG and OAM traffic) during WAB-node mobility, including the case where the WAB-MT’s BH PDU session changes. Support the UE’s AMF change for UEs connected to, or camped on, a WAB-gNB. UE’s ULI that reflect the WAB node’s location. The handling of: PCI collision avoidance. Reconfiguration ofTAC and RANAC on WAB-gNBs. Mechanisms to avoid multi-hop WAB topology. Radio-resource coordination between access and backhaul links. NG connection management. I AB

[0007] In 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR), Integrated Access and Backhaul (IAB) is a technique for providing wireless backhaul as an alternative to a fibre backhaul network. An IAB network comprises IAB nodes, at which wireless resources are shared between wireless backhaul and access links. By means of such a configuration, it is possible to install nodes without the necessity of providing a fibre data connection, thereby allowing speedy and simple roll out of network coverage to locations where no such data connection is available or possible. Due to the limited coverage area of an IAB node, the backhaul network is typically implemented as a multi-hop network with backhaul traffic traversing multiple IAB nodes.

[0008] FIG. 2 (adapted from TR 38.874 “Study on Integrated Access and Backhaul”, VI6.0.0, December 2018) shows a two-hop IAB network as described in 3GPP NR Rel-16 and further enhanced in Rel-17. 3GPP 5G Release 16 was the first release comprising the IAB feature. Release 17 comprised enhancements on top of the Release 16 baseline and is now frozen. Work on Release 18 is currently underway to develop and improve features relating to IAB relative to previous Releases, most notably the mobility of IAB nodes. Assumption in previous Releases was that IAB nodes are stationary. BSR and pre-emptive BSR

[0009] In NR and LTE networks, in order to assist scheduling done by the base station / access point, the terminal (UE) provides feedback on the occupancy of its buffers - it reports the amount of data in the UE Uplink (UL) buffer available for transmission. This mechanism is known as Buffer Status Reporting, or BSR, and is a function of the MAC layer. BSR can be trigger-based or configured to be sent periodically and uses several different formats (3GPP TS 38.321). For purposes of BSR, radio bearers / logical channels (LCHs) are grouped into LCH groups, or LCGs. A BSR is typically encapsulated as a Medium Access Control (MAC) Control Element (CE).

[0010] An IAB node features, at least conceptually, a base station part (or DU), and an MT part, as shown in the previous section. In a multi-hop network, latency delays from a node not being able to request resources until data is received from its child node (despite already having knowledge of incoming data e.g. via BSR received from child node), are likely to accumulate due to the number of hops and aggregated volume of data at IAB nodes. It may therefore be beneficial for the MT part of an IAB node to request uplink (UL) resources for the UL data transmission from its parent node even before it actually receives the data to be transmitted from its child node. This is why pre-emptive BSR was introduced into Rel-16 IAB, which can be seen in FIG. 3. FIG. 3 illustrates: A) Operation without pre-emptive BSR, B) triggering preemptive BSR based on UL grant and C) triggering pre-emptive BSR based on receiving a BSR. The BSR formats are identified by MAC subheaders with predefined LCID values, while a Preemptive BSR format is identified by a MAC subheader with a predefined eLCID value.

[0011] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention. SUMMARY

[0012] It is an aim of certain examples of the present disclosure to address, solve and / or mitigate, at least partly, at least one of the problems and / or disadvantages associated with the related art, for example at least one of the problems and / or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein.

[0013] The present invention is defined in the independent claims. Advantageous features are defined in the dependent claims.

[0014] Embodiments or examples disclosed in the description and / or figures falling outside the scope of the claims are to be understood as examples useful for understanding the present invention.

[0015] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 illustrates a WAB node and how it relates to UEs, the backhaul gNB, backhaul 5GC, neighbouring gNBs and the 5GC of a UE.

[0017] FIG. 2 illustrates a two-hop IAB network as described in 3GPP NR Rei-16 and further enhanced in Rei-17.

[0018] FIG. 3 illustrates: A) Operation without pre-emptive BSR, B) triggering pre-emptive BSR based on UL grant and C) triggering pre-emptive BSR based on receiving a BSR.

[0019] FIG. 4 is a signal flow diagram illustrating an aspect of the present disclosure.

[0020] FIG. 5A is a signal flow diagram illustrating an aspect of the present disclosure.

[0021] FIG. 5B is a signal flow diagram illustrating an aspect of the present disclosure.

[0022] FIG. 6 is a signal flow diagram illustrating an aspect of the present disclosure.

[0023] FIG. 7 is a signal flow diagram illustrating an aspect of the present disclosure.

[0024] FIG. 8 is a signal flow diagram illustrating an aspect of the present disclosure.

[0025] FIG. 9 is a signal flow diagram illustrating an aspect of the present disclosure.

[0026] FIG. 10 illustrates an example method of a WAB node in a communication network in examples of the present disclosure.

[0027] FIG. 11 illustrates an example method of a WAB node in a communication network in examples of the present disclosure.

[0028] FIG. 12 is a block diagram of an exemplary network entity that may be used in examples of the present disclosure. DETAILED DESCRIPTION

[0029] The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of the present invention, as defined by the claims. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made.

[0030] The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings.

[0031] Detailed descriptions of techniques, structures, constructions, functions or processes known in the art may be omitted for clarity and conciseness, and to avoid obscuring the subject matter of the present disclosure.

[0032] The terms and words used herein are not limited to the bibliographical or standard meanings, but, are merely used to enable a clear and consistent understanding of the examples disclosed herein.

[0033] Throughout the description and claims, the words “comprise”, “contain” and “include”, and variations thereof, for example “comprising”, “containing” and “including”, means “including but not limited to”, and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, functions, characteristics, and the like.

[0034] Throughout the description and claims, the singular form, for example “a”, “an” and “the”, encompasses the plural unless the context otherwise requires. For example, reference to “an object” includes reference to one or more of such objects.

[0035] Throughout the description and claims, language in the general form of “X for Y” (where Y is some action, process, function, activity or step and X is some means for carrying out that action, process, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y.

[0036] Features, elements, components, integers, steps, processes, functions, characteristics, and the like, described in conjunction with a particular aspect, embodiment, example or claim are to be understood to be applicable to any other aspect, embodiment, example or claim disclosed herein unless incompatible therewith.

[0037] The following examples are applicable to, and use terminology associated with, 3 GPP 5G. However, the skilled person will appreciate that the techniques disclosed herein are not limited to these examples or to 3GPP 5G, and may be applied in any suitable system or standard, for example one or more existing and / or future generation wireless communication systems or standards. The skilled person will appreciate that the techniques disclosed herein may be applied in any existing or future releases of 3GPP 5G NR or any other relevant standard.

[0038] For example, the functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in other communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function, operation or purpose within the network. For example, the functionality of an WAB node in the examples below may be applied to any other suitable type of entity performing functions of a network node, and in particular to any type of relay node.

[0039] The skilled person will appreciate that certain examples of the present disclosure may not be directly related to standardization but rather proprietary implementation of some of the WAB functions or non-WAB related functions of NR Rei-17 and beyond networks.

[0040] The skilled person will appreciate that the present invention is not limited to the specific examples disclosed herein. For example: • The techniques disclosed herein are not limited to 3GPP 5G. • The techniques disclosed herein are not limited to WAB or relay networks. • One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations. • One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information. • One or more further elements, entities and / or messages may be added to the examples disclosed herein. • One or more non-essential elements, entities and / or messages may be omitted in certain examples. • The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example. • The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example. • Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example. • Information carried by two or more separate messages in one example may be carried by a single message in an alternative example. • The order in which operations are performed may be modified, if possible, in alternative examples. • The transmission of information between network entities is not limited to the specific form, type and / or order of messages described in relation to the examples disclosed herein.

[0041] Certain examples of the present disclosure may be provided in the form of an apparatus / device / network entity configured to perform one or more defined network functions and / or a method therefor. Such an apparatus / device / network entity may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). Certain examples of the present disclosure may be provided in the form of a system (e.g. a network) comprising one or more such apparatuses / devices / network entities, and / or a method therefor. For example, in the following examples, a network may include one or more WAB or relay nodes.

[0042] It will be appreciated that examples of the present disclosure may be realized in the form of hardware, software or a combination of hardware and software. Certain examples of the present disclosure may provide a computer program comprising instructions or code which, when executed, implement a method, system and / or apparatus in accordance with any aspect, claim, example and / or embodiment disclosed herein. Certain embodiments of the present disclosure provide a machine-readable storage storing such a program.

[0043] Pre-emptive BSR was introduced for IAB nodes in order to increase scheduling efficiency by an IAB node pre-emptively sending a BSR if either the IAB node receives a BSR or SR from a UE or a child IAB node, or if the IAB node sends an UL grant to schedule a UE or a child node.

[0044] The pre-emptive BSR may be triggered for any type of uplink data that a UE or child node indicates in the uplink BSR. This is relevant for an IAB node, as the IAB node is only the DU of a gNB, which means that all data (user plane and much of control signaling including RRC) intended to a gNB needs to be forwarded from an IAB node to its parent CU via the backhaul network of IAB nodes.

[0045] Pre-emptive BSR may also be useful for a range of relay or repeater nodes, such as WAB. In WAB however, currently only a single hop is being discussed, which means that not necessarily all data that is sent to a WAB shall be forwarded on the backhaul link, since the WAB features a full gNB inside the WAB node. This means that some data sent by a UE may be terminated in the WAB node. This means that pre-emptive BSR may need to be adjusted to be useful for WAB as it does not apply to WAB in its current form, and the issue identified above (need to ensure that Pre-BSR only covers data which will eventually be forwarded) is a new issue identified by the inventors of the present invention.

[0046] Aspects of the invention relate to methods for modifying the concept of scheduling latency reduction via pre-emptive BSR, by adapting pre-emptive BSR and related techniques to the WAB use-case. While this invention is described in terms of a WAB node, it may also apply to other types of repeaters or relays. For instance it may apply to any type of 6G relay or repeater node.

[0047] In the description below, the description may apply to eNBs, gNBs, en-gNBs, NG-RANs or NG-eNB. For instance, in some cases the below description may be for an eNB, but it may also apply for NG-eNB (eNB is connected to EPC, while NG-eNB is connected to 5GC). In some cases below, there may also be methods explicitly for an NG-eNB, en-gNB, gNB, or NG-RAN.

[0048] In a first aspect of the invention any type of relay node may be configured to preemptively signal buffer status reports or other scheduling assistance information on the backhaul link in response to conditions at the node, where the conditions are related to specific received data from a UE or other node or predicting that data will have to be transmitted or forwarded over the backhaul link based on a procedure that the UE or another node is performing.

[0049] This can be configured by the gNB that is backhauling the node, i.e the backhaul gNB or the donor gNB, or it may a configuration that is available by default for a relay node.

[0050] The pre-emptively signalled buffer status or other scheduling assistance information may be sent over the backhauling link to the backhauling gNB by the -MT (the part that communicates with the backhauling gNB) part of the node.

[0051] In another aspect of the invention, the WAB node may be configured to pre-emptively signal buffer status reports or other scheduling assistance information on the WAB backhaul link in response to conditions at the WAB-gNB, where the conditions are related to specific received data from a UE or other node or predicting that data will have to be transmitted or forwarded over the backhaul link based on a procedure that the UE or another node is performing.

[0052] This can be configured by the gNB that is backhauling the WAB node, i.e the Backhaul gNB, or it may a configuration that is available by default for a WAB node.

[0053] The pre-emptively signalled buffer status or other scheduling assistance information may be sent over the backhauling link to the backhauling gNB by the WAB-MT.

[0054] FIG. 4 illustrates an aspect in which a relay node (e.g. a WAB node) pre-emptively signals scheduling assistance information (e.g. pre-emptive BSR) on a backhaul connection (e.g. WAB backhaul) in response to conditions at the relay node.

[0055] In step 1 of FIG. 4, the relay node (e.g. a WAB node) identifies a condition at the relay node. The condition may relate to a first network node (e.g. a UE). The condition may be at least one of determining, based on information (e.g. a BSR) received from the first network node, that data will have to be transmitted over the backhaul connection, and determining, based on identifying a procedure being performed or to be performed by at least one of the first network node, the relay node or the second network node, that data will have to be transmitted by the relay node over the backhaul connection.

[0056] In some examples, determining, based on information received from the first network node, that data will have to be transmitted over the backhaul connection may comprise: receiving information indicating data to be transmitted to the relay node; and determining if the indicated data comprises data to be transmitted over the backhaul connection.

[0057] In some examples, transmitting the scheduling assistance information comprises: including, in the scheduling assistance information, information related to data to be transmitted over the backhaul connection from among the data to be transmitted to the relay node; and excluding, from the scheduling assistance information, information related to data not to be transmitted over the backhaul connection from among the data to be transmitted to the relay node.

[0058] In step 2 of FIG. 4, in response to identifying the condition, the relay node transmits, to a second network node (e.g. backhaul gNB) over the backhaul connection, scheduling assistance information (e.g. pre-emptive BSR).

[0059] In step 3 of FIG. 4, data may be received from the first network node and at least part of the data may be forwarded to the second network node.

[0060] In one aspect of the invention, any type of relay node, such as a WAB, may be configured to pre-emptively signal buffer status reports or other scheduling assistance information based on expected messages that may need to be sent to the core network or to another node. Examples of this may for instance be messages sent from the relay node to an AMF, such as NGAP messages. Another example may be messages that shall be sent from any type of relay node to another radio access node, which can for instance be from the relay node, which may be a gNB, to another gNB. This may for instance be for messages over Xn or any other NB to NB interface.

[0061] In one aspect of the invention, any type of relay node, such as WAB, may be configured to pre-emptively signal buffer status reports or other scheduling assistance information based on the MAC entity being aware of the destination of the related data. If for instance the relay node knows that certain data is not to be forwarded, the relay node does not trigger a pre-emptive buffer status report or other scheduling assistance information. Similarly, if the relay node knows that the data is to be forwarded to another node, then the relay may trigger the pre-emptive buffer status report. Conditions based on Radio bearer type

[0062] The conditions for triggering or sending a pre-emptive buffer status report or any other scheduling assistance information by a relaying node may be related to what type of data (user plane or control plane) a UE or another node attaching to said node indicates to be available, and / or the destination of said data, or what type of data or messages that are being sent by a UE or another node to the WAB-gNB.

[0063] In one aspect of the invention, the pre-emptively sent buffer status report or other scheduling information is not triggered for certain data or based on certain scheduling information sent from a UE or another node based on where the data is terminated. For instance, the pre-emptively sent buffer status report or other scheduling information is not triggered for control plane data originating from the UE. This may be because such control plane data may be control plane data or messages that are terminated in the WAB-node and are not transferred to the core network. Example of such data would be RRC messages such as measurement reports, different types of RRC requests, or similar.

[0064] This may also imply that the pre-emptively sent buffer status report or other scheduling information is only triggered for user plane data, for instance data for a Data Radio Bearer (DRBs), originating from the UE or another node. Such user plane data may be messages that are terminated outside the WAB-node. Such messages may be user plane data from a UE. Control plane data that is terminated in the core network of the UE, for instance NAS messages may also trigger the pre-emptively sent buffer status report or other scheduling information.

[0065] FIG. 5A illustrates an example in which data that will have to be transmitted over the backhaul connection (e.g. user plane data) is indicated to a relay node (e.g. WAB node).

[0066] In step 1 of FIG. 5A, the relay node may receive information (e.g. BSR) from the first network node (e.g. UE) indicating data to be transmitted to the relay node. The information may indicate that the data to be transmitted to the relay node is data that will have to be transmitted over the backhaul connection (e.g. user plane data).

[0067] In step 2 of FIG. 5A, if the information indicates that the data to be transmitted to the relay node is data that will have to be transmitted over the backhaul connection, the relay node may transmit, to the second network node over the backhaul connection, scheduling assistance information (e.g. pre-emptive BSR).

[0068] In step 3 of FIG. 5A, the relay node may receive the data (e.g. user plane data) to be transmitted over the backhaul connection.

[0069] In step 4 of FIG. 5A, the relay node may transmit the data (e.g. user plane data) to the second network node (e.g. BH gNB).

[0070] FIG. 5B illustrates an example in which data that will not have to be transmitted over the backhaul connection (e.g. control plane data) is indicated to a relay node (e.g. WAB node).

[0071] In step 1 of FIG. 5B, the relay node may receive information (e.g. BSR) from the first network node (e.g. UE) indicating data to be transmitted to the relay node. The information may indicate that the data to be transmitted to the relay node is data that will not have to be transmitted over the backhaul connection (e.g. control plane data).

[0072] In step 2 of FIG. 5B, if the information indicates that the data to be transmitted to the relay node is data that will not have to be transmitted over the backhaul connection, the relay node may determine not to transmit, to the second network node over the backhaul connection, scheduling assistance information (e.g. pre-emptive BSR).

[0073] In step 3 of FIG. 5B, the relay node may receive the data (e.g. control plane data) not to be transmitted over the backhaul connection.

[0074] In order to achieve such filtering of how pre-emptive BSRs are triggered, in one aspect of the invention, the WAB may for instance not trigger pre-emptive BSR based on whether data from a specific logical channel or logical channel group that carries a specific type of radio bearer (may be SRB or DRB, or other future types of radio bearers) or its associated logical channel groups are present in a received BSR. Or similarly, if the WAB receives specific types of scheduling requests, which indicates that a specific logical channel or logical channel group that indicates a signaling or data radio bearer having data for transmission do not have allocated uplink resources, the WAB may not trigger pre-emptive BSR..

[0075] Similarly, the WAB may for instance trigger pre-emptive BSR based on whether data from a specific logical channel or logical channel group that carries a specific type of radio (may be SRB or DRB, or other future types of radio bearers) or its associated logical channel groups are present in a received BSR. If the WAB receives specific types of scheduling requests, which indicates that a specific logical channel or logical channel group that indicates a signaling or data radio bearer having data for transmission do not have allocated uplink resources, the WAB may trigger pre-emptive BSR.

[0076] In one aspect of the invention, the network signals specific radio bearers which may or may not trigger pre-emptive BSR. This can for instance be useful as in some cases, the RRC messages such as SRB2 may contain NAS messages, which needs to be forwarded in an NGAP message sent to the BH-gNB to be forwarded to the UE core network. For instance the WAB is configured with preemptive BSR to only be triggered for user plane or data radio bearers, the network can configure a flag use PreBSR-DRB, as seen in example.

[0077] Pre-emptive BSR is currently triggered at the MAC layer. In order for some of the embodiments of the invention to work within this framework, in some of the embodiments additional indication and / or configuration from the RRC to the MAC is provided, for instance to indicate to the MAC layer the type of message being carried in a certain LCH and / or LCG. In another embodiment, triggering or pre-BSR happens at the RRC layer - in other words, decision on whether to trigger pre-BSR or other scheduling assistance information is done at the RRC layer, which then indicates to the MAC layer that pre-BSR should be sent.

[0078] FIG. 6 illustrates steps for this type of operation:

[0079] 0. The second network node (e.g. BH-gNB) configures the relay node (e.g WAB-MT) with (i.e. to use) pre-emptive signaling assistance information (e.g. pre-emptive BSR) and the relay node (e.g. WAB-gNB) configures the first network node (e.g. UE) with (i.e. to use) buffer status reports.

[0080] 1. First network node (e.g. UE) receives uplink data in the buffer and triggers a buffer status report.

[0081] 2. First network node (e.g. UE) sends a Buffer Status report to the relay node (e.g. WAB-gNB).

[0082] 3. Relay node (e.g. WAB-gNB) identifies the one or more radio bearers associated with the buffer status reports and determines whether to trigger pre-emptive signaling assistance information (e.g. a pre-emptive BSR) to the second network node (BH-gNB).

[0083] 4. Relay node (e.g. WAB) triggers pre-emptive signaling assistance information (e.g. a pre-emptive BSR) and relay node (e.g. WAB-MT) sends the pre-emptive signaling assistance information (e.g. pre-emptive BSR) over the backhaul link to the second network node (BH-gNB).

[0084] 5. The relay node (e.g. WAB-gNB) schedules the first network node (UE) to transmit in the uplink. This may for instance be done via an uplink grant.

[0085] 6a. The second network node (e.g. BH-gNB) schedules the relay node (e.g. WAB-MT) to transmit in the uplink based on the received pre-emptive signaling assistance information (e.g. pre-emptive BSR).

[0086] 6b. The first network node (e.g. UE) transmits in the uplink.

[0087] 7. The relay node (e.g. WAB-MT) may forward the received uplink transmission to the second network node (BH-gNB), which may then be backhauled through the backhaul core network to an entity such as the AMF or the UPF of the UEs core network.

[0088] In one aspect of the invention, when a WAB calculates the size of the pre-emptive BSR, i.e. the buffer that the WAB would have after receiving the uplink data from the UE, the WAB may calculate the buffer based on expect size after the encapsulation has been performed. In other words, the size of the buffer may add the IP header size etc. in addition to the buffer size in the buffer status report from the UE.

[0089] In another aspect of the invention, the WAB may add a pre-configured amount of bits to the pre-emptive BSR on top of the received buffer size from a UE. This can be configured by the network. If the network does not configure this, a pre-defined offset may be used. For instance if a UE indicates that a radio bearer, which shall be able to trigger a pre-emptive BSR has 1400 bits, then the WAB may add a configured 100 bits to account for various headers.

[0090] In some examples, transmitting the scheduling assistance information may comprise including, in the scheduling assistance information, information related to data to be transmitted over the backhaul connection from among the data to be transmitted to the relay node; and excluding, from the scheduling assistance information, information related to data not to be transmitted over the backhaul connection from among the data to be transmitted to the relay node.

[0091] For example, the WAB may exclude certain radio bearers when calculating the preemptive BSR depending on whether those specific radio bearer types may trigger the preemptive BSR. In other words, if certain radio bearer associated with logical channels or logical channel groups in the BSR shall not be forwarded or sent to the BH-gNB, then when calculating the pre-emptive BSR, these do not need to be included in the pre-emptive BSR. Conditions based on expected NGAP / Xn

[0092] In one aspect of the invention, the WAB triggers a pre-emptive Buffer Status Report based on certain RRC procedures that the UE is performing or is predicted to perform with a WAB-gNB (terminated / originating from UE / WAB-gNB). This may mean that certain control plane procedures may trigger pre-emptive BSRs. This can for instance be important when a control plane procedure of a UE triggers messages that shall be forwarded, or other messages that may be triggered to any of the BH-gNB, the BH core network or the UE’s core network, for instance when something is to be sent over NGAP to the UE’s AMF. It may also be important if the WAB expects that a UE procedure may trigger inter-node messages, i.e. messages to another gNB over Xn to be sent. In this case the WAB may have to backhaul the Xn messages to the BH-gNB which then sends the Xn messages to another gNB.

[0093] In one aspect of the invention, the WAB triggers a pre-emptive BSR during the RRC Setup procedure of a UE. This can for instance be in response to the WAB-gNB sending an RRCSetup message to a UE, or it may be in response to receiving an RRCSetupRequest from a UE. This is important, because the UE may include a NAS message in the RRCSetupComplete message, which needs to be sent over the NGAP interface and thus backhauled to the UEs AMF via the BH-gNB and BH CN. This message may be the INITIAL CONTEXT SETUP REQUEST or INITIAL UE MESSAGE message that is sent from an NG-RAN to an AMF. The expectation that INITIAL CONTEXT SETUP REQUEST or INITIAL UE MESSAGE will be sent may also be considered to be the trigger that triggers the pre-emptive BSR. To have to wait for uplink scheduling for this case may delay the setup procedures. An example of this type of procedure can be seen in FIG. 7.

[0094] FIG. 7 illustrates an example of the relay node determining based on identifying a procedure being performed by the first network node or based on identifying a procedure to be performed by the first network node, that data will have to be transmitted over the backhaul connection.

[0095] The UE may initially be in RRC Idle. In step 1 of FIG. 7, the UE may transmit an RRCSetupRequest message to the WAB-gNB.

[0096] In step 2 of FIG. 7, the WAB-gNB may transmit an RRCSetup message to the UE so that the UE may move to RRC Connected, and may determine, based on the RRC setup procedure, that data will have to be transmitted over the backhaul connection. In response to the determination, the WAB-gNB may transmit, to the BH-gNB, a pre-emptive BSR.

[0097] In step 3 of FIG. 7, the WAB-gNB may receive, from the BH-gNB, an UL grant.

[0098] In step 4 of FIG. 7, the WAB-gNB may receive, from the UE, an RRCSetupComplete message which may include a NAS message / initial UE message, such as INITIAL CONTEXT SETUP REQUEST or INITIAL UE MESSAGE.

[0099] In step 5 of FIG. 7, the WAB-gNB may transmit, to the UE CN (via the BH-gNB and BH-CN), the uplink data including the initial UE message.

[0100] In another aspect of the invention, if a UE triggers an RRC resume procedure, i.e. a procedure to enter RRC CONNECTED from RRC INACTIVE, the UE may trigger a preemptive BSR. This can be triggered based on WAB gNB receiving an RRC Resume Request or transmitting an RRC Resume message to a UE. It can also be considered to be triggered based on expecting to transmit the RRC INACTIVE TRANSITION REPORT or an UE CONTEXT RESUME REQUEST to an AMF (or other core network entity).

[0101] In one aspect of the invention, the NAS transport may trigger a pre-emptive BSR. For instance, if the WAB-gNB anticipates an uplink NAS message to be sent to an AMF (or other core network entity), the WAB-gNB may pre-emptively send a pre-emptive BSR.

[0102] In another aspect of the invention, if the WAB-gNB expects a UE CONTEXT RESUME REQUEST to be sent to an AMF (or other core network entity) or a PATH SWITCH REQUEST, then the WAB-gNB may trigger a pre-emptive BSR. This may be in response to a UE performing an RRC resume procedures, re-establishment or due to UE performing a handover. For instance, since a PATH SWITCH REQUEST may be sent to an AMF during a handover procedure after the UE has successfully synchronized to the cell, the WAB-gNB may trigger a pre-emptive BSR during the handover procedure.

[0103] A paging attempt may also trigger the WAB-gNB to send a pre-emptive BSR. This would be reserved for any type of signalling required during the UE performing paging. This may for instance be triggered when or in response to the WAB-gNB sending a Paging message to a UE.

[0104] The following further messages may trigger a pre-emptive BSR if they are expected to be transmitted by a gNB to an AMF: • UE CONTEXT RELEASE REQUEST • RAN CP RELOCATION INDICATION • RETRIEVE UE INFORMATION • HANDOVER REQUIRED • HANDOVER NOTIFICATION • HANDOVER CANCEL • UPLINK RAN STATUS TRANSFER • UPLINK RAN EARLY STATUS TRANSFER • UPLINK NAS TRANSPORT

[0105] In another set of aspects of the invention, the WAB-gNB may trigger a pre-emptive buffer status report based on expected messages sent over inter-node interface such as Xn.

[0106] In one aspect of the invention, the UE may trigger a pre-emptive buffer status report based on expected HANDOVER REQUEST messages from WAB-gNB to target RAN node (target may be another WAB-gNB or any type of RAN node). This may also be triggered based on the WAB-gNB predicting a handover would soon need to be performed. An example of this type of process is illustrated in FIG. 8. For instance the WAB-gNB may be a mobile node that may need to handover a lot of UEs at the same time. This may for instance be in the case that a WAB-MT performs a handover and changes its backhaul gNB, In this case, the WAB-gNB may be able to trigger the pre-emptive BSR to ensure that handover procedure may be as fast as possible. The WAB-gNB may also use knowledge of UE signal quality or UE signal strength to predict the WAB-gNB needing to send a HANDOVER REQUEST to another gNB.

[0107] FIG. 8 illustrates an example of pre-emptive scheduling assistance information during handover. The source WAB-gNB may predict that a handover will soon be performed. For example, the source WAB-gNB may identify that a handover will be (or should be) performed within a predetermined or preconfigured duration from the present time. In the case that the WAB-gNB predicts a handover, in step 1 of FIG. 8 the source WAB-gNB may transmit preemptive scheduling assistance information (e.g. pre-emptive BSR) to the BH-gNB.

[0108] In step 2 of FIG. 8, the source WAB-gNB may receive, from the BH-gNB, an UL grant.

[0109] In step 3 of FIG. 8, the source WAB-gNB may transmit, to the target gNB (via the BH-gNB and BH-CN) uplink data, for example including a handover request.

[0110] In step 4 of FIG. 8, the source WAB-gNB may receive, from the target gNB (via the BH-gNB and BH-CN), downlink data, for example including a handover request acknowledgement.

[0111] In step 5 of FIG. 8, for example in response to receiving the handover request acknowledgement, the source WAB-gNB may transmit a handover command to the UE.

[0112] In step 6 of FIG. 8, the UE may be handed over to the target gNB.

[0113] Other mobility-related messages that may trigger the pre-emptive BSR, for instance if the message is triggered to be sent, or in advance where it is predicted that the message will be sent, where the WAB-gNB may either be the target or the source gNB: • HANDOVER REQUEST ACKNOWLEDGE • SN STATUS TRANSFER • HANDOVER CANCEL • RETRIEVE UE CONTEXT REQUEST / RESPONSE • RAN PAGING • XN-U ADDRESS INDICATION • UE CONTEXT RELEASE • HANDOVER SUCCESS • CONDITIONAL HANDOVER CANCEL • EARLY STATUS TRANSFER

[0114] Other procedures may also trigger pre-emptive BSRs where the WAB-gNB is the initiating node, source node, first node or old RAN node. Procedures may also trigger the pre emptive BSR where the WAB-gNB is that receiving node, target node, secondary node or new RAN node.

[0115] The above may mean that the RRC of the WAB-gNB may indicate to the MAC layer of the WAB-MT to trigger a pre-emptive BSR.

[0116] In one aspect of the invention, the WAB-gNB may be configured by the network to trigger pre-emptive BSR for specific cases. For instance, the WAB-gNB may configured by the network to trigger BSR based only on the handover procedure. This may for instance mean that the WAB-gNB is only allowed to trigger pre-emptive BSR based on expecting that messages such as PATH SWITCH REQUEST, HANDOVER REQUIRED, HANDOVER NOTIFICATION, HANDOVER CANCEL, HANDOVER REQUEST, HANDOVER REQUEST ACKNOWLEDGE etc may trigger the pre-emptive BSR. In another example, if any setup procedure is allowed to trigger the pre-emptive BSR, this may for instance mean that the messages INITIAL UE MESSAGE, INITIAL UE CONTEXT SETUP, PATH SWITCH REQUEST, RRC INACTIVE TRANSITION REPORT, UE CONTEXT RESUME REQUEST etc. may trigger a pre-emptive BSR. Scheduling assistance information

[0117] In one aspect of the invention, the pre-emptive BSR or any other pre-emptive (or otherwise) scheduling information includes an indication of what triggered the sending of said information. For instance if, a data radio bearer triggered a pre-emptive BSR, then this may be indicated. If a handover or RRC setup procedure triggered the pre-emptive BSR, then this may be indicated to the backhauling gNB. This can be useful in assigning priority to certain messages over the other. If a new UE or relay node of a certain type or category has attached or requested access, then this may be indicated. In a multi-hop extension of WAB, where WAB connects to another WAB and not directly to a BH-gNB, the number of hops the data needs to traverse to reach the BH-gNB may also be indicated. Other

[0118] The WAB node, or other relay or repeater node, may either be configured by its backhaul gNB or donor gNB to pre-emptively send a buffer status report, or this may be default operation that does not need to be configured.

[0119] In one aspect of the invention, if the already existing pre-emptive BSR (the RRC configuration userPreBSR-r!6 in MAC-CellGroupConfig) is configured for a WAB-MT, the methods in this invention may apply, and the WAB-gNB and the IAB methods for triggering the pre-emptive BSR may not be applicable. In other words, if a WAB-gNB is configured with pre-emptive BSR, the WAB-gNB does not apply the IAB methods.

[0120] In another aspect of this invention, if the already existing pre-emptive BSR (the RRC configuration userPreBSR-rl6 in MAC-CellGroupConfig) is configured for a WAB-MT, the conventional pre-emptive BSR may apply, while the methods in this invention will apply when configured using dedicated new signaling.

[0121] Extended pre-emptive BSR may also be applicable to a WAB-gNB. The extended preemptive BSR may for instance be applicable if the network configures the logicalChannelGroupIAB, or the network may configure a WAB-specific configuration. In one aspect of the invention, the extended pre-emptive BSR is considered to be supported by the WAB. This means that if any type of pre-emptive BSR is configured to the WAB, then the WAB uses the extended pre-emptive BSR.

[0122] The WAB-MT may indicate to a BH-gNB its capability to support pre-emptive BSR.

[0123] In one aspect of the invention, the WAB-MT may be configured to trigger a preemptive BSR after the WAB-MT has performed a handover. This may be required for two reasons. One reason is that the WAB-MT may need to send a number of messages in order to establish the backhauling channel. This for instance includes messages to setup the NGAP setup between WAB-gNB and the BH AMF, BH UPF or BH CN. An example of this type of process is illustrated in FIG. 9 . The pre-emptive BSR may also be needed in order for the WAB to handle UEs performing handover to and from the WAB-gNB. This may for instance be if the UEs AMF changes, or there is a new tracking area signalled by the WAB.

[0124] FIG. 9 illustrates an example of pre-emptive scheduling assistance information triggered as WAB-MT is handed over.

[0125] In step 1 of FIG. 9, the first (i.e. source) and second (i.e. target) BH gNBs / CNs may determine and prepare to hand over the WAB.

[0126] In step 2 of FIG. 9, the first BH-gNB may transmit a handover command to the WAB, indicating that the WAB should be handed over to the second BH-gNB.

[0127] In step 3a of FIG. 9, the handover to the second BH-gNB may be performed, and in step 3b the WAB may determine that the handover has been successful.

[0128] In step 4 of FIG. 9, in response to determining that the handover has been successful, the WAB may transmit pre-emptive scheduling assistance information (e.g. pre-emptive BSR) to the second BH-gNB.

[0129] In step 5 of FIG. 9, setup of the WAB-gNB may be initiated.

[0130] In step 6 of FIG. 9, setup of the WAB-gNB may be performed with the second BH-CN (via the second BH-gNB).

[0131] The pre-emptive buffer status report may be used in a setting where the relay node is in a dual connectivity setting. Such a dual connectivity setting may for instance mean that the relay node, such as a WAB node, has two backhaul gNBs and two backhaul core networks, for instance if each BH node connects to different core networks. In this case, the pre-emptive BSR is triggered for each backhaul gNB depending on the destination. This for instance means that the buffer status report received on one should not be taken to include the full WAB buffer, but only the buffer for each backhaul node. This may be important, as a WAB may not have any other means of routing data.

[0132] FIG. 10 illustrates an example method of a WAB node in a communication network.

[0133] In step 1002, the method comprises identifying a condition at the WAB node.

[0134] In step 1104, in response to identifying the condition, the method comprises transmitting, to a second network node (e.g. gNB) over a backhaul connection, scheduling assistance information.

[0135] The condition may be at least one of: determining, based on a buffer status report (BSR) received from a first network node (e.g. a UE), that data will have to be transmitted over the backhaul connection; and determining, based on identifying a procedure being performed, to be performed, or having been performed by at least one of the first network node, the WAB node or the second network node, that data will have to be transmitted by the WAB node over the backhaul connection.

[0136] FIG. 11 illustrates an example method of a WAB node in a communication network.

[0137] In step 1102, the method comprises identifying a condition at the WAB node.

[0138] In step 1104, in response to identifying the condition, the method comprises transmitting, to a backhaul gNB over a backhaul connection, a pre-emptive BSR.

[0139] The condition may be at least one of: identifying that an UL grant is provided to a UE in response to a BSR that indicates a logical channel not associated with a system resource block (SRB); identifying that a BSR is received from a UE and that the BSR indicates at least one logical channel not associated with an SRB; identifying a trigger from the RRC layer; and identifying that a message will be sent over at least one of the NGAP and Xn interfaces.

[0140] FIG. 12 is a block diagram of an exemplary network entity 1200 (e.g. relay node or WAB node) that may be used in examples of the present disclosure. The skilled person will appreciate that the network entity 1200 illustrated in FIG. 12 may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[0141] The network entity 1200 comprises a processor 1201 (or controller), a transmitter 1202 and a receiver 1203. The receiver 1203 is configured for receiving one or more messages from one or more other network entities. The transmitter 1202 is configured for transmitting one or more messages to one or more other network entities. The processor 1201 is configured for performing operations as described above. Specification examples There follows examples of changes to the existing 3GPP standards based on the present disclosure. Changes are shown in bold typeface. --------------- 38.321 Release 18 VI8.2.0--------------- 5.4.7 Pre-emptive Buffer Status Reporting The Pre-emptive Buffer Status reporting (Pre-emptive BSR) procedure is used by an IAB-MT or WAB-MT to provide its parent IAB-DU(s), lAB-donor-DU(s) or BH-gNB with the information about the amount of the data expected to arrive at the IAB-MT or WAB-MT from its child node(s) and / or UE(s) connected to it. If configured, Pre-emptive BSR may be triggered for the specific case of an IAB-MT or WAB-MT if any of the following events occur: - UL grant is provided to child IAB node or UE; - UL grant is provided to UE in response to a BSR that indicates a logical channels not associated with an SRB; - BSR is received from child IAB node or UE. - BSR is received from a UE and the BSR indicates a logical channels not associated with an SRB. - Triggered by RRC layer (for WAB-MT) IAB-MT or WAB-MT may report Extended Pre-emptive BSR (as defined in clause 6.1.3.1) if the MAC entity of the IAB-MT or WAB-MT is configured with logicalChamelGroupIAB-Ext by upper layers. Otherwise IAB-MT or WAB-MT may report Pre-emptive BSR (as defined in clause 6.1.3.1). The MAC entity shall: 1> if the Pre-emptive Buffer Status reporting procedure determines that at least one Pre-emptive BSR has been triggered and not cancelled: 2> if UL-SCH resources are available for a new transmission and the UL-SCH resources can accommodate the Extended Pre-emptive BSR or Pre-emptive BSR MAC CE plus its subheader as a result of logical channel prioritization: 3> instruct the Multiplexing and Assembly procedure to generate the Extended Pre-emptive BSR or Pre-emptive BSR MAC CE as defined in clause 6.1.3.1. 2> else: 3>trigger a Scheduling Request. A MAC PDU shall contain at most one Pre-emptive BSR MAC CE or Extended Pre-emptive BSR MAC CE, even when multiple events have triggered a Pre-emptive BSR. All triggered Pre-emptive BSR(s) shall be cancelled when a MAC PDU is transmitted and this PDU includes the corresponding Pre-emptive BSR MAC CE or Extended Pre-emptive BSR MAC CE. NOTE: Pre-emptive BSR may be used for the case of dual-connected IAB node. It is up to network implementation to work out the associated MAC entity or entities which report the Pre-emptive BSR, and the associated expected amount of data reported by any such entity or entities. For the case of dual-connected IAB node, if two ingress BH RLC channels belonging to the same ingress LCG are mapped to two different egress Cell Groups (corresponding to different parent nodes), there may be ambiguity in Preemptive BSR calculations and interpretation by the receiving parent node(s) and the IAB node reporting pre-emptive BSR. --------------- 38.321 Release 18 V18.2.0--------------- Example #1b --------------- 38.331 Release 18 VI8.2.0--------------- MAC-CellGroupConfig The IE MAC-CellGroupConfig is used to configure MAC parameters for a cell group, including DRX. MAC-CellGroupConfig information element SSSASSlSTAgTi ......i..................................................................................................................................................................................................................................................... drx-C'jnflg SetupRelesse { PKI-Config } OPTIONAL, -- Need M ecliedullnqF’.e'guestCenf iq SehedulinqRequeetCedfig OPTIONA.L, -- Nee-i tl phr-denflg_______________________SqtuqPd-lqq.se { PHR-Ounfi ql_________OPTIONAL. -- Need M nipUplinhTzlRdi aiiuc BOOLEAN: 1111111111111111111111^^ PPPPPAihiiApidiPRiPPPPPPPPPPPPPPPPPPPPPPPPPPp: iiiiiiigOOiOliiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii datalnaotivit'pTiiner SetupReleaae { Dat.aInaeti''it'pTimei } OPTIONAL -- Gand MCG-only iilillllllliilllllllllllllliilllllllllllllllllllilllllllllllllllllllll Ilillllilililililii^ useFreBPR-i'lI echedulingReopieetlD-LBT-CCell-ile SohednlingReojueetld OPTIONAL, -- Need F. llililiiiAANpgOiddiOliOiliO^ ENUMERATED {enabled} OPTIuNaL, -- Need R I he dnllli (R- pie_ y ID-BFF-1 >ell-L 1' I die lulm (Fe _[il~ltl 1 OPTION-L, -- IRa 1 F IIIIIIIIIIIIIIIIIIIIIIIIIII SetupReieaee { BRE-Conf igSeoondaryGio>ip-L 11 } enhanoedBhipUplinhTaiDpnaiiiic-Ll':' ENNIIEFlATED {tine} OPTIO1L-.L, -- Need R enhancedSJ:ipUplinl;Ta;Conf igured~rl’5 ENUMERATEB (true} OPTIONAL -- Need R SSSSSSSINS / SSSSSS ilillllilililililii :::::::::::::::::::: :g i i Ai i i Ai i i^^Ji^ ^i^ ^i i i ig i i ig i i Ai i i i i i i i i i i^ Sjpsssssssssssssssssssssssssssssssssssss aehedulingRequeatlB-FopFlG-Requeet-rlT SchedulingReap-ie.atld OPTIONAL, — Need R diiz-LastTr anemieeienNL-r 1" lllliillllllllllllllllllllll ENUIIERATED {enabled} OPTIONAL -- Need R ilillllilililililii pe=I IG-Request-l 1 iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii^ iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii d r a: - C ■ a n f i g Ex 12 - v 1S 0 0 addi ti'analEE-TableAlle-' ed-i 1S d a r-Co n f i gT oAddMo dL i s t-r1E sliiaNii iiiiu | UlIllNlIIIIIII I dei-'Rapf ipT-aReleaeeLiet-rld iiiiiiiliiiiiiiiiiiiiiiiiiiiiiiiiii^ii EetupRelease { PRII-CenfigEaitl-vlyOg } OPTIONAL, -- Need H BIT BTRING iSILE niiaa:NrofLCG.3-rr: J I OPTIONAL, — Need R SEQUENCE (SIZE (1. . inanNr of LCGs-r 1U ) ) OF LCG-DSR-Conf ig-rlS SEQUENCE (SHE f 1, .luaaiNrofLCGa-ilS) ) OF LCG-Id-rls sssssbaSeGaBbegASiiSsssssssssssss iiiii^iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii^ SetupRelease { TAR-Gonfig-rlS } OPTIO1LAL -- Need H iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii aisasasSSHAiSSBSjiSBiiBsiASlis iiiiiitiiiiiiiiiiiiiiiiiiiiii }} i i i i i i i i }i E?g?ig?SGWWEB?:NjSd?SS: RgiSgO^OOEggORgggg^ liiliiliiiiiiiiiiiiiiiiiiiiiiiiii^ii MAC-CellGroupConfig The IE MAC-CellGroupConfig is used to configure MAC parameters for a cell group, including DRX. MAC-CellGroupConfig information element ilsASltOiWssSsSsSsSss -- TAG-1 AC-CELLGFXHPCOHFIG-CTAFT' HAC-CellGicupCnnfig : : = gigigiiilggggggl^ggigigiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii s ch e du1i n g Fa q ue c t C o n f i g tag-Conf ig c kipUp1i nkTxFVn ami c llllllllllllllllllll da t a I n u c t i vi t yT in a r igNAggiPPPPPPPPPPPPPPPPPPPPPPPPPPi 11111^111111111 iOogOlip; TetupReieaae { DRA-Config }: lilililiiiOhedUliOiA&eiA^ ggggg^igig}igg^g^g.igigi^ggggggggggggggpgggggg PPPPPTggpgdhigpigPPPPPPPPPPPPPPPPPPPpI AtupAlAA { PHF-Ccnfig }: iiiiiiiiiiiiiiiii|||iO ggORWIIIII OPTIONAL, -- Need Hi OPTIONAL, -- Need IF OPTIONAL, -- Need Hi OPTIONAL, — Need Mi OPTIONAL, -- Need Fli { DatalnactivitpTimeL OPTIONAL, — Need H } OPTIONAL — Gund MCG- schedulingRequeLtID-LBT-SCell-rli SchedulingReguestId OPTIONAL, -- Need Ri leh-BaeedpLi'jritiiati’?n-Lle E1RU IERA.TEB {enabled} OPTION.AL, -- Heed R sc.hedulingRequeetlD-BFR-BCell-rld CchedulingR&quLSt Id OPTION.AL, -- Need R dL-?:~C'jnfidSecC'ridsiryGLe'UP'-rle SetupRelesee { pRv-c.jnfidSecc.nddL’yGie'UP'-rl¢- } OiiSBssSsSssBssOaisisissSsSsSsSsSsSsSsSsSsSsSsSsSs issssssssssssssssssssssssssssssssssss d rx - Co n f i g Ex 12 - vl U U U addiLionelBB-TahleAlle' ed-r 1S del- Co n f i gT oAddHo dL i e t-11L deL-OoufidToEeleeoeLiet-rlB iiiiilililillllliillililils^ iiiiiiiiiiWSAgsHigiqAgiigiiiiiiiiiiiiiiiii / ilillillilililililil BetupRelease { BRN-ConfigE?:t 1-- / 11 OP } OPTIONAL, -- Need II BIT BTRIHG (BICE <'m3?:NrcTLCGs-rl - J I OPTIONAL, — Heed Ri BEQHEHi E <BICE 1,1..1110 llL.fL>G / -Ll )) OF L> G-DBF-> . lit 1 g-L 1 SEQUENCE iSIEE (1. .UuXNrC'fLCGg-L-ll) ) OF LCG-Id-rlU SetupFlelease { TAR-Config-rll } OPTIONAL -- Need II ENUMERATED {true} Ui: iiiiiiiiooMiWiiOi® TAG-IIAC-CELLGROUPCONFIG-CTOP ______________________________MAC-CellGroupConfig field descriptions_____________________________ ____________________________________________________... OMITTED ...___________________________________________________ usePreBSR If set to true, the MAC entity of the IAB-MT may use the Pre-emptive BSR, see TS 38.321 [3].___________________ usePreBSR-DRB If set to true, the MAC entity of the WAB-MT or others may use the Pre-emptive BSR for Data Radio Bearers, see TS 38.321 [3]. --------------- 38.331 Release 18 VI8.2.0--------------- Example #2 Specification changes in bold. --------------- 38.321 Release 18 V18.2.0--------------- 5.4.7 Pre-emptive Buffer Status Reporting The Pre-emptive Buffer Status reporting (Pre-emptive BSR) procedure is used by an IAB-MT to provide its parent IAB-DU(s) or lAB-donor-DU(s) with the information about the amount of the data expected to arrive at the IAB-MT from its child node(s) and / or UE(s) connected to it. If configured, Pre-emptive BSR may be triggered for the specific case of an IAB-MT if any of the following events occur: - UL grant is provided to child IAB node or UE; - BSR is received from child IAB node or UE. - Triggered by UE RRC procedures by the WAB-gNB, as described in 38.300. IAB-MT may report Extended Pre-emptive BSR (as defined in clause 6.1.3.1) if the MAC entity of the IAB-MT is configured with logicalChannelGroupIAB-Ext by upper layers. Otherwise IAB-MT may report Pre-emptive BSR (as defined in clause 6.1.3.1). The MAC entity shall: 1> if the Pre-emptive Buffer Status reporting procedure determines that at least one Pre-emptive BSR has been triggered and not cancelled: 2> if UL-SCH resources are available for a new transmission and the UL-SCH resources can accommodate the Extended Pre-emptive BSR or Pre-emptive BSR MAC CE plus its subheader as a result of logical channel prioritization: 3> instruct the Multiplexing and Assembly procedure to generate the Extended Pre-emptive BSR or Pre-emptive BSR MAC CE as defined in clause 6.1.3.1. 2> else: 3>trigger a Scheduling Request. A MAC PDU shall contain at most one Pre-emptive BSR MAC CE or Extended Pre-emptive BSR MAC CE, even when multiple events have triggered a Pre-emptive BSR. All triggered Pre-emptive BSR(s) shall be cancelled when a MAC PDU is transmitted and this PDU includes the corresponding Pre-emptive BSR MAC CE or Extended Pre-emptive BSR MAC CE. NOTE: Pre-emptive BSR may be used for the case of dual-connected IAB node. It is up to network implementation to work out the associated MAC entity or entities which report the Pre-emptive BSR, and the associated expected amount of data reported by any such entity or entities. For the case of dual-connected IAB node, if two ingress BH RLC channels belonging to the same ingress LCG are mapped to two different egress Cell Groups (corresponding to different parent nodes), there may be ambiguity in Preemptive BSR calculations and interpretation by the receiving parent node(s) and the IAB node reporting pre-emptive BSR. --------------- 38.321 Release 18 V18.2.0--------------- --------------- 38.331 Release 18 VI8.2.0--------------- 10.4 Measurements to Support Scheduler Operation Measurement reports are required to enable the scheduler to operate in both uplink and downlink. These include transport volume and measurements of a UEs radio environment. Uplink buffer status reports (BSR) are needed to provide support for QoS-aware packet scheduling. In NR, uplink buffer status reports refer to the data that is buffered in for a group of logical channels (LCG) in the UE. Four formats are used for reporting in uplink: - A short format to report only one BSR (of one LCG); - A flexible long format to report several BSRs (up to all eight LCGs); - An extended short format to report one BSR (of one LCG); - An extended long format to report several BSRs (up to all 256 LCGs). NOTE: The Extended versions of the BSR formats can only be used by IAB nodes. Uplink buffer status reports are transmitted using MAC signalling. When a BSR is triggered (e.g. when new data arrives in the transmission buffers of the UE), a Scheduling Request (SR) can be transmitted by the UE (e.g. when no resources are available to transmit the BSR). For IAB, the Pre-emptive BSR can be configured on the backhaul links. The Pre-emptive BSR is sent based on expected data rather than buffered data, as described in clause 4.7.3.3. For WAB, the Pre-emptive BSR can be configured on the backhaul links. The Pre-emptive BSR may be triggered by a WAB-gNB based on predicted messages to be sent over NGAP or Xn. Power headroom reports (PHR) are needed to provide support for power-aware packet scheduling. In NR, three types of reporting are supported: a first one for PUSCH transmission, a second one for PUSCH and PUCCH transmission in an LTE Cell Group in EN-DC (see TS 37.340

[21] ) and a third one for SRS transmission on SCells configured with SRS only. In case of CA, when no transmission takes place on an activated SCell, a reference power is used to provide a virtual report. To allow network to detect UL power reduction, the PHR reports may also contain Power Management Maximum Power Reduction (P-MPR, see TS 38.101-2

[35] ) information that UE uses to ensure UE compliance with the Maximum Permissible Exposure (MPE) exposure regulation for FR2, which is set for limiting RF exposure on human body. Power headroom reports are transmitted using MAC signalling. --------------- 38.331 Release 18 VI8.2.0---------------

[0142] While the invention has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention, as defined by the appended claims.

[0143] Certain examples of the present disclosure provide one or more techniques as disclosed in the specification examples above. The skilled person will appreciate that any of these techniques may be applied in combination with any of the techniques described above and illustrated in the Figures.

[0144] In a first example, there is provided a method of a relay node in a communication network, the method comprising: identifying a condition at the relay node; and in response to identifying the condition, transmitting, to a second network node over a backhaul connection, scheduling assistance information; wherein the condition is at least one of: determining, based on information received from a first network node, that data will have to be transmitted over the backhaul connection, and determining, based on identifying a procedure being performed or to be performed by at least one of the first network node, the relay node or the second network node, that data will have to be transmitted by the relay node over the backhaul connection.

[0145] In a second example, there is provided the method of the first example, wherein the relay node is a wireless access backhaul (WAB) node.

[0146] In a third example, there is provided the method of the first or second example, wherein the information indicating data to be transmitted over the backhaul connection comprises a BSR.

[0147] In a fourth example, there is provided the method of any one of the first to third examples, wherein determining, based on information received from a first network node, that data will have to be transmitted over the backhaul connection comprises: receiving information indicating data to be transmitted to the relay node; and determining if the indicated data comprises data to be transmitted over the backhaul connection.

[0148] In a fifth example, there is provided the method of the fourth example, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection comprises: identifying if the indicated data comprises user plane data; and determining that the indicated data is data to be transmitted over the backhaul connection if the data is user plane data.

[0149] In a sixth example, there is provided the method of the fourth or fifth examples, wherein transmitting the scheduling assistance information comprises: including, in the scheduling assistance information, information related to data to be transmitted over the backhaul connection from among the data to be transmitted to the relay node; and excluding, from the scheduling assistance information, information related to data not to be transmitted over the backhaul connection from among the data to be transmitted to the relay node.

[0150] In a seventh example, there is provided the method of any one of the first to sixth examples, wherein the scheduling assistance information comprises a pre-emptive buffer status report (BSR).

[0151] In an eighth example, there is provided the method of any one of the first to seventh examples, wherein identifying a procedure being performed or to be performed by at least one of the first network node, the relay node or the second network node comprises identifying at least one of: an RRC setup procedure, an RRC resume procedure, another RRC procedure, and a handover procedure.

[0152] In a ninth example, there is provided the method of any one of the first to eighth examples, wherein the scheduling assistance information includes information indicating the identified condition.

[0153] In a tenth example, there is provided the method of any one of the first to ninth examples, wherein the transmitting of the scheduling assistance information is configured by the second network node.

[0154] In an eleventh example, there is provided the method of any one of the first to tenth examples, wherein the data that will have to be transmitted over the backhaul connection is at least one of: UE CONTEXT RELEASE REQUEST, RAN CP RELOCATION INDICATION, RETRIEVE UE INFORMATION, HANDOVER REQUIRED, HANDOVER NOTIFICATION, HANDOVER CANCEL, UPLINK RAN STATUS TRANSFER, UPLINK RAN EARLY STATUS TRANSFER, UPLINK NAS TRANSPORT, HANDOVER REQUEST ACKNOWLEDGE, SN STATUS TRANSFER, HANDOVER CANCEL, RETRIEVE UE CONTEXT REQUEST / RESPONSE, RAN PAGING, XN-U ADDRESS INDICATION, UE CONTEXT RELEASE, HANDOVER SUCCESS, CONDITIONAL HANDOVER CANCEL, EARLY STATUS TRANSFER.

[0155] In a twelfth example, there is provided a method of a wireless access backhaul (WAB) node in a communication network, the method comprising: identifying a condition at the WAB node; and in response to identifying the condition, transmitting, to a backhaul gNodeB (gNB) over a backhaul connection, a pre-emptive buffer status report (BSR); wherein the condition is at least one of: identifying that an uplink (UL) grant is provided to user equipment (UE) in response to a BSR that indicates a logical channel not associated with a system resource block (SRB), identifying that a BSR is received from a UE and the BSR indicates a logical channels not associated with an SRB, identifying a trigger from the radio resource control (RRC) layer, and identifying that a message will be sent over at least one of the NGAP and Xn interfaces.

[0156] In a thirteenth example, there is provided the method of the twelfth example, wherein the WAB node is a WAB mobile termination (WAB-MT) node.

[0157] In a fourteenth example, there is provided the method of the twelfth or thirteenth examples, wherein the transmitting of the scheduling assistance information is configured over the backhaul connection.

[0158] In a fifteenth example, there is provided a first network entity (e.g. a relay node or WAB node) configured to operate according to a method of any of the first to fourteenth examples.

[0159] In a sixteenth example, there is provided a second network entity (e.g. a relay node or WAB node) configured to cooperate with a first network entity of the fifteenth example according to a method of any one of the first to fourteenth examples.

[0160] In a seventeenth example, there is provided a network or wireless communication system comprising a first network entity according to the fifteenth example and a second network entity according to the sixteenth example.

[0161] In an eighteenth example, there is provided a computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any one of the first to fourteenth examples.

[0162] In a nineteenth example, there is provided a computer or processor-readable data carrier having stored thereon a computer program according to the eighteenth example.

[0163] In a twentieth example, there is provided a method of a wireless access backhaul (WAB) node in a communication network, the method comprising: identifying a condition at the WAB node; and in response to identifying the condition, transmitting, to a second network node (e.g. gNB) over a backhaul connection, scheduling assistance information; wherein the condition is at least one of: determining, based on a buffer status report (BSR) received from a first network node (e.g. a UE), that data will have to be transmitted over the backhaul connection, and determining, based on identifying a procedure being performed, to be performed, or having been performed by at least one of the first network node, the WAB node or the second network node, that data will have to be transmitted by the WAB node over the backhaul connection.

[0164] In a twenty-first example, there is provided the method of the twentieth example, wherein determining, based on a BSR received from a first network node, that data will have to be transmitted over the backhaul connection comprises: receiving the BSR indicating data to be transmitted to the WAB node; and determining if the indicated data comprises data to be transmitted over the backhaul connection.

[0165] In a twenty-second example, there is provided the method of the twenty-first example, further comprising: identifying the condition if the indicated data comprises data to be transmitted over the backhaul connection; and not identifying the condition if the indicated data comprises data that is not to be transmitted over the backhaul connection.

[0166] In a twenty-third example, there is provided the method of the twenty-first or twenty-second example, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection comprises determining based on at least one of: data type, data destination, logical channel, logical channel group, radio bearer, radio bearer type, uplink resources.

[0167] In a twenty-fourth example, there is provided the method of the twenty-third example, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection based on data type comprises: identifying if the indicated data comprises user plane data; and determining that the indicated data is data to be transmitted over the backhaul connection if the data is at least one of: user plane data, or control plane data that is terminated in the core network of the first network node.

[0168] In a twenty-fifth example, there is provided the method of the twenty-third or twentyfourth example, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection based on data type comprises: determining that the indicated data is not data to be transmitted over the backhaul connection if the data is not at least one of: user plane data, or control plane data that is terminated in the core network of the first network node.

[0169] In a twenty-sixth example, there is provided the method of any of the twenty-first to twenty-fifth examples, wherein transmitting the scheduling assistance information comprises: including, in the scheduling assistance information, information related to data to be transmitted over the backhaul connection from among the data to be transmitted to the WAB node; and excluding, from the scheduling assistance information, information related to data not to be transmitted over the backhaul connection from among the data to be transmitted to the WAB node.

[0170] In a twenty-seventh example, there is provided the method of any of the twentieth to twenty-sixth examples, wherein the scheduling assistance information comprises a pre-emptive BSR.

[0171] In a twenty-eighth example, there is provided the method of any of the twentieth to twenty-seventh examples, wherein identifying a procedure being performed or to be performed by at least one of the first network node, the WAB node or the second network node comprises identifying at least one of: an RRC setup procedure, an RRC resume procedure, another RRC procedure, and a handover procedure.

[0172] In a twenty-ninth example, there is provided the method of any of the twentieth to twenty-eighth examples, wherein the scheduling assistance information includes at least one of: information indicating the identified condition; information indicating that a new UE has attached or requested access; information indicating that a new relay node has attached or requested access; a number of hops needed to reach a base station.

[0173] In a thirtieth example, there is provided the method of any of the twentieth to twenty-ninth examples, wherein the transmitting of the scheduling assistance information is configured by the second network node.

[0174] In a thirty-first example, there is provided the method of any of the twentieth to thirtieth examples, wherein the data that will have to be transmitted over the backhaul connection is at least one of: UE CONTEXT RELEASE REQUEST, RAN CP, RELOCATION INDICATION, RETRIEVE UE INFORMATION, HANDOVER REQUIRED, HANDOVER NOTIFICATION, HANDOVER CANCEL, UPLINK RAN STATUS TRANSFER, UPLINK RAN EARLY STATUS TRANSFER, UPLINK NAS TRANSPORT, HANDOVER REQUEST ACKNOWLEDGE, SN STATUS TRANSFER, HANDOVER CANCEL, RETRIEVE UE CONTEXT REQUEST / RESPONSE, RAN PAGING, XN-U ADDRESS INDICATION, UE CONTEXT RELEASE, HANDOVER SUCCESS, CONDITIONAL HANDOVER CANCEL, EARLY STATUS TRANSFER.

[0175] In a thirty-second example, there is provided the method of any of the twentieth to thirty-first examples, wherein identifying the condition at the WAB node comprises identifying the condition at the WAB node in at least one of: the MAC layer, or the RRC layer.

[0176] In a thirty-third example, there is provided the method of any of the twentieth to thirty-second examples, wherein the scheduling assistance information indicates a buffer size, and wherein the method further comprises: determining the buffer size based on at least one of: an expected buffer size, a network-configured offset, or a predetermined offset.

[0177] In a thirty-fourth example, there is provided the method of any of the twentieth to thirty-third examples, further comprising: receiving, from the first network node, data; and forwarding, to the second network node, at least part of the data over the backhaul connection.

[0178] In a thirty-fifth example, there is provided the method of the thirty-fourth example, wherein the forwarded data is the data determined as having to be transmitted over the backhaul connection based on the BSR.

[0179] In a thirty-sixth example, there is provided the method of any of the twentieth to thirty-fifth examples, further comprising indicating, to the second network node, that the WAB node supports transmitting the scheduling assistance information.

[0180] In a thirty-seventh example, there is provided the method of any of the twentieth to thirty-sixth examples, wherein the WAB node has a first backhaul connection to the second network entity, and a second backhaul connection to a third network entity (e.g. gNB), and wherein the method further comprises identifying the condition based on a whether the data will have to be transmitted over the first backhaul connection or the second backhaul connection.

[0181] In a thirty-eighth example, there is provided the method of any of the twentieth to thirty-seventh examples, wherein identifying a procedure being performed, to be performed, or having been performed by at least one of the first network node, the WAB node or the second network node comprises identifying messages expected to be transmitted by the WAB node.

[0182] In a thirty-ninth example, there is provided a method of a wireless access backhaul (WAB) node in a communication network, the method comprising: identifying a condition at the WAB node; and in response to identifying the condition, transmitting, to a backhaul gNodeB (gNB) over a backhaul connection, a pre-emptive buffer status report (BSR); wherein the condition is at least one of: identifying that an uplink (UL) grant is provided to a user equipment (UE) in response to a BSR that indicates a logical channel not associated with a system resource block (SRB), identifying that a BSR is received from a UE and the BSR indicates a logical channel(s) not associated with an SRB, identifying a trigger from the radio resource control (RRC) layer, and identifying that a message will be sent over at least one of the NGAP and Xn interfaces.

[0183] In a fortieth example, there is provided the method of the thirty-ninth example, wherein the WAB node is a WAB mobile termination (WAB-MT) node.

[0184] In a forty-first example, there is provided the method of the thirty-ninth or fortieth example, wherein the transmitting of the scheduling assistance information is configured over the backhaul connection.

[0185] In a forty-second example, there is provided a first network entity (e.g. a WAB node) configured to operate according to a method of any of the twentieth to forty-first examples.

[0186] In a forty-third example, there is provided a second network entity (e.g. a gNB) configured to cooperate with a first network entity of the forty-second example according to a method of any one of the twentieth to forty-first examples.

[0187] In a forty-fourth example, there is provided a network or wireless communication system comprising a first network entity according to the forty-second example and a second network entity according to the forty-third example.

[0188] In a forty-fifth example, there is provided a computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any one of the twentieth to forty-first examples.

[0189] In a forty-sixth example, there is provided a computer or processor-readable data carrier having stored thereon a computer program according to the forty-fifth example. ABBREVIATIONS / DEFINITIONS In the present disclosure, the following abbreviations and definitions may be used. 3 GPP 3rd Generation Partnership Project NAS Non-Access Stratum 5G 5th Generation NG Interface between 5G RAN and Core 5 GO 5G Core NGAP Next Generation Application Protocol AMF Access and Mobility Management Function NR New Radio BH Backhaul PDU Packet Data Unit BSR Buffer Status Report QoS Quality of Service CP Control Plane RAN Radio Access Network CU Central Unit RAN2 Radio layer 2 and Radio layer 3 Working DU Distributed Unit Group eLCID extended LCID Rei Release Fl interface between DU and CU RLC Radio Link Control gNB 5G base station RRC Radio Resource Control IAB Integrated Access and Backhaul SCH Shared Channel ID Identity / Identification TR Technical Report IP Internet Protocol TS Technical Specification IE Information Element UE User Equipment LCG Logical Channel Group UL UpLink LCH Logical Channel UP User Plane LCID Logical Channel ID UPF User Plane Function LTE Long Term Evolution Uu Air interface between terminal and base MAC Medium Access Control station / access point MT Mobile Termination Xn Interface between 2 base stations

Claims

1. A method of a wireless access backhaul (WAB) node in a communication network, the method comprising:identifying a condition at the WAB node; andin response to identifying the condition, transmitting, to a second network node (e.g. gNB) over a backhaul connection, scheduling assistance information;wherein the condition is at least one of:determining, based on a buffer status report (BSR) received from a first network node (e.g. a UE), that data will have to be transmitted over the backhaul connection, and determining, based on identifying a procedure being performed, to be performed, or having been performed by at least one of the first network node, the WAB node or the second network node, that data will have to be transmitted by the WAB node over the backhaul connection.

2. The method of claim 1, wherein determining, based on a BSR received from a first network node, that data will have to be transmitted over the backhaul connection comprises:receiving the BSR indicating data to be transmitted to the WAB node; anddetermining if the indicated data comprises data to be transmitted over the backhaul connection.

3. The method of claim 2, further comprising:identifying the condition if the indicated data comprises data to be transmitted over the backhaul connection; andnot identifying the condition if the indicated data comprises data that is not to be transmitted over the backhaul connection.

4. The method of claim 2 or 3, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection comprises determining based on at least one of:data type,data destination,logical channel,logical channel group,radio bearer,radio bearer type,uplink resources.

5. The method of claim 4, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection based on data type comprises:identifying if the indicated data comprises user plane data; anddetermining that the indicated data is data to be transmitted over the backhaul connection if the data is at least one of:user plane data, orcontrol plane data that is terminated in the core network of the first network node.

6. The method of claim 4 or 5, wherein determining if the indicated data comprises data to be transmitted over the backhaul connection based on data type comprises:determining that the indicated data is not data to be transmitted over the backhaul connection if the data is not at least one of:user plane data, orcontrol plane data that is terminated in the core network of the first network node.

7. The method of any of claims 2 to 6, wherein transmitting the scheduling assistance information comprises:including, in the scheduling assistance information, information related to data to be transmitted over the backhaul connection from among the data to be transmitted to the WAB node; andexcluding, from the scheduling assistance information, information related to data not to be transmitted over the backhaul connection from among the data to be transmitted to the WAB node.

8. The method of any preceding claim, wherein the scheduling assistance information comprises a pre-emptive BSR.

9. The method of any preceding claim, wherein identifying a procedure being performed or to be performed by at least one of the first network node, the WAB node or the second network node comprises identifying at least one of:an RRC setup procedure,an RRC resume procedure, another RRC procedure, and a handover procedure.

10. The method of any preceding claim, wherein the scheduling assistance information includes at least one of:information indicating the identified condition;information indicating that a new UE has attached or requested access; information indicating that a new relay node has attached or requested access; a number of hops needed to reach a base station.

11. The method of any preceding claim, wherein the transmitting of the scheduling assistance information is configured by the second network node.

12. The method of any preceding claim, wherein the data that will have to be transmitted over the backhaul connection is at least one of:- UE CONTEXT RELEASE REQUEST- RAN CP RELOCATION INDICATION- RETRIEVE UE INFORMATION- HANDOVER REQUIRED- HANDOVER NOTIFICATION- HANDOVER CANCEL- UPLINK RAN STATUS TRANSFER- UPLINK RAN EARLY STATUS TRANSFER- UPLINK NAS TRANSPORT- HANDOVER REQUEST ACKNOWLEDGE- SN STATUS TRANSFER- HANDOVER CANCEL- RETRIEVE UE CONTEXT REQUEST / RESPONSE- RAN PAGING- XN-U ADDRESS INDICATION- UE CONTEXT RELEASE- HANDOVER SUCCESS- CONDITIONAL HANDOVER CANCEL- EARLY STATUS TRANSFER.

13. The method of any preceding claim, wherein identifying the condition at the WAB node comprises identifying the condition at the WAB node in at least one of:the MAC layer, or the RRC layer.

14. The method of any preceding claim, wherein the scheduling assistance information indicates a buffer size, and wherein the method further comprises:determining the buffer size based on at least one of:an expected buffer size, a network-configured offset, or a predetermined offset.

15. The method of any preceding claim, further comprising: receiving, from the first network node, data; and forwarding, to the second network node, at least part of the data over the backhaul connection.

16. The method of claim 15, wherein the forwarded data is the data determined as having to be transmitted over the backhaul connection based on the BSR.

17. The method of any preceding claim, further comprising indicating, to the second network node, that the WAB node supports transmitting the scheduling assistance information.

18. The method of any preceding claim, wherein the WAB node has a first backhaul connection to the second network entity, and a second backhaul connection to a third network entity (e.g. gNB), and wherein the method further comprises identifying the condition based on a whether the data will have to be transmitted over the first backhaul connection or the second backhaul connection.

19. The method of any preceding claim, wherein identifying a procedure being performed, to be performed, or having been performed by at least one of the first network node, the WAB nodeor the second network node comprises identifying messages expected to be transmitted by the WAB node.

20. A method of a wireless access backhaul (WAB) node in a communication network, the method comprising:identifying a condition at the WAB node; andin response to identifying the condition, transmitting, to a backhaul gNodeB (gNB) over a backhaul connection, a pre-emptive buffer status report (BSR);wherein the condition is at least one of:identifying that an uplink (UL) grant is provided to a user equipment (UE) in response to a BSR that indicates a logical channel not associated with a system resource block (SRB), identifying that a BSR is received from a UE and the BSR indicates a logical channel(s) not associated with an SRB,identifying a trigger from the radio resource control (RRC) layer, andidentifying that a message will be sent over at least one of the NGAP and Xn interfaces.

21. The method of claim 20, wherein the WAB node is a WAB mobile termination (WAB-MT) node.

22. The method of claim 20 or 21, wherein the transmitting of the scheduling assistance information is configured over the backhaul connection.

23. A first network entity (e.g. a WAB node) configured to operate according to a method of any preceding claim.

24. A second network entity (e.g. a gNB) configured to cooperate with a first network entity of claim 23 according to a method of any one of claim 1 to claim 22.

25. A network or wireless communication system comprising a first network entity according to claim 23 and a second network entity according to claim 24.T +44(0)30 0300 2000A

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