WO2022056932A1

WO2022056932A1 - Resource efficiency enhancements for iab networks

Info

Publication number: WO2022056932A1
Application number: PCT/CN2020/116609
Authority: WO
Inventors: Dawid Koziol; Xiang Xu; Guillaume DECARREAU; Ilkka Keskitalo; Matti Laitila; Samuli Turtinen
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2020-09-21
Filing date: 2020-09-21
Publication date: 2022-03-24
Also published as: CN116508278A

Abstract

An IAB network node, part of a RAN in communication with a UE, performs the following: receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction; in the downlink direction, receiving first data over a backhaul link for a single DRB associated with the UE, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the UE; and in the uplink direction, receiving second data over multiple uplink traffic flows from the UE, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link. Additional techniques use IAB DU and CU nodes.

Description

RESOURCE EFFICIENCY ENHANCEMENTS FOR IAB NETWORKS

TECHNICAL FIELD

Exemplary embodiments herein relate generally to wireless communication networks and, more specifically, relates to networks having Integrated Access and Backhaul (IAB) .

BACKGROUND

In a cellular communications system, the term “backhaul” is used to denote a communication path from base station to base station or from base station to the core network. Typically, the backhaul from a base station to the core network uses very high-speed communication such as fiber optic communications. Backhaul between base stations was initially wired, but recently there has been a trend toward wireless backhaul between base stations in certain situations.

For instance, an Integrated Access and Backhaul (IAB) feature was introduced in third generation partnership project (3GPP) Rel-16 (release 16) specifications. Thanks to this feature, it is possible to relay user traffic over, e.g., a wireless interface (e.g., Uu) between two relaying nodes called IAB nodes. The relaying may take place over one or multiple hops (referred to as air interface segments) .

While the IAB feature has benefits, it also poses challenges. For instance, a base station might use the same spectrum or wireless channel to serve the mobile devices (referred to as user equipment (UEs) ) in its coverage as well as to provide backhaul connectivity other base stations. This and other resource challenges can lead to resource inefficiency.

BRIEF SUMMARY

This section is intended to include examples and is not intended to be limiting.

In an exemplary embodiment, a method is disclosed that includes in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following: receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction; in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.

An additional exemplary embodiment includes a computer program, comprising code for performing the method of the previous paragraph, when the computer program is run on a processor. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the computer.

An exemplary apparatus includes one or more processors and one or more memories including computer program code. The one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus to perform operations comprising: in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following: receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction; in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.

An exemplary computer program product includes a computer-readable storage medium bearing computer program code embodied therein for use with a computer. The computer program code includes: code for, in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following: receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction; in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.

In another exemplary embodiment, an apparatus comprises means for performing: in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following: receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction; in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.

In an exemplary embodiment, a method is disclosed that includes receiving data for a user equipment at an integrated access and backhaul donor distributed unit node, and determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated. The method also includes adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data, and forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.

An exemplary apparatus includes one or more processors and one or more memories including computer program code. The one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus to perform operations comprising: receiving data for a user equipment at an integrated access and backhaul donor distributed unit node; determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated; adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.

An exemplary computer program product includes a computer-readable storage medium bearing computer program code embodied therein for use with a computer. The computer program code includes: code for receiving data for a user equipment at an integrated access and backhaul donor distributed unit node; code for determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated; code for adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and code for forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.

In another exemplary embodiment, an apparatus comprises means for performing: receiving data for a user equipment at an integrated access and backhaul donor distributed unit node; determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated; adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.

In an exemplary embodiment, a method is disclosed that includes at an integrated access and backhaul donor control unit in a network, performing the following: determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.

An exemplary apparatus includes one or more processors and one or more memories including computer program code. The one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus to perform operations comprising: at an integrated access and backhaul donor control unit in a network, performing the following: determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.

An exemplary computer program product includes a computer-readable storage medium bearing computer program code embodied therein for use with a computer. The computer program code includes: code for at an integrated access and backhaul donor control unit in a network, performing the following: determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.

In another exemplary embodiment, an apparatus comprises means for performing: at an integrated access and backhaul donor control unit in a network, performing the following: determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.

BRIEF DESCRIPTION OF THE DRAWINGS

In the attached Drawing Figures:

FIG. 1 is a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced;

FIG. 2 illustrates an overall IAB architecture, where FIG. 2A illustrates IAB-node configuration using CA mode with NGC, and FIG. 2B illustrates IAB-node config using EN-DC;

FIG. 3 illustrates parent-node and child-node relationship for IAB nodes;

FIG. 4 illustrates protocol stacks for the support of F1-U protocol (left-hand side) and F1-C Protocol (right-hand side) ;

FIG. 5 illustrates routing and BH RLC channel selection on BAP sublayer;

FIG. 6 illustrates a resource inefficiency issue in the IAB network for carrying radio bearers configured with PDCP packet duplication using Carrier Aggregation (CA) (Scenario 1) and Dual Connectivity (DC) (Scenario 2) ;

FIG. 7 is a block diagram illustrating a duplicate handling function in the access IAB node for CA based duplication, in accordance with a first exemplary embodiment;

FIG. 8 a flowchart for the first embodiment, where a UE is configured with CA duplication; and

FIG. 9 is a block diagram illustrating a duplicate discard function in the inter-mediate IAB node for DC based duplication, in accordance with a second embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

Abbreviations that may be found in the specification and/or the drawing figures are defined below, at the end of the detailed description section.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims.

The exemplary embodiments herein describe techniques for resource efficiency enhancements for IAB networks. Additional description of these techniques is presented after a system into which the exemplary embodiments may be used is described.

Turning to FIG. 1, this figure shows a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced. A user equipment (UE) 110, multiple IAB nodes 170 and 170-1, and network element (s) 190 are illustrated. In FIG. 1, a user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless, typically mobile device that can access a wireless network. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a control module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways. The control module 140 may be implemented in hardware as control module 140-1, such as being implemented as part of the one or more processors 120. The control module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the control module 140 may be implemented as control module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with IAB node 170-1 via a wireless link 111, and the IAB node 170 communicates with the IAB donor node 170 via a backhaul link 176.

Illustrated are two IAB network nodes 170 and 170-1, where the IAB network node 170 is represented in an example as a donor node. More details are provided below about possible network structures using IAB network nodes 170, 170-1 (and additional IAB nodes) but it is assumed for simplicity that the circuitry between the IAB network nodes 170, 170-1 is similar. That is, there would be (as described below) processors and memories and computer program code in each of the IAB network nodes 170 and 170-1, and the operations performed by the various nodes network 170/170-1 can be implemented in hardware, software, or a combination of both, as described below. Therefore, only the circuitry of the IAB network node 170 is illustrated.

It is further noted that the Central Unit (CU) 196 and Distributed Unit (DU) are shown being part of the IAB donor node 170. This is, however, for ease of exposition, and DU and CU are typically separated in cloud RAN implementations, for instance. Thus, the DU 195 and CU 196 parts of the IAB network node 170 may be physically separated, and each would have their own processors/memories/computer program code. It is further noted that the IAB DU may also be referred to as an IAB DU node, as in the case where the DU is separated from the CU, each of the DU and CU may be its own node. As used herein, an integrated access and backhaul network node can be either an IAB node 170-x (where “x” is 1, 2, …) or an IAB DU node 195.

The IAB network nodes 170/170-1 are base stations that provides access by wireless devices such as the UE 110 to the wireless network 100, and may be a donor node (170) or an IAB node (170-1) . The donor node 170 typically connects to the core network, illustrated in part here using the network element (s) 190. This connection is illustrated as link 131, which is typically a fiber optics link but may be any other suitable link.

The IAB network node 170 may be, for instance, a base station for 5G, also called New Radio (NR) . In 5G, the IAB node 170 may be a NG-RAN node, which is defined as either a gNB or an ng-eNB. As a clarification, in non-stand-alone (NSA) network, an IAB can be deployed with an EN-DC (EUTRAN NR Dual Connectivity) connection, where the serving node for an IAB node can be an eNB (Master Node) . However, the eNB provides only the control interface and the backhaul (BH) (e.g., data) is carried over a NR leg of DC. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (e.g., the network element (s) 190) . The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit (s) (DUs) (gNB-DUs) , of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU) . The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB. There is an F1-C connection between CU and DU over which the CU controls the DU using F1AP protocol. The gNB-CU terminates the F1 interface connected with the gNB-DU. The F1 interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the IAB network node 170 and centralized elements of the IAB network node 170, such as between the gNB-CU 196 and the gNB-DU 195. In terms of a CU 196 connected to a DU 195-1, a link 198-1 is alThe gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of an RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The IAB node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution) , or any other suitable base station.

The IAB node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F (s) ) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor (s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory/memories (and corresponding computer program code) and processor (s) , and/or other hardware, but these are not shown.

The IAB node 170 includes a control module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways. The control module 150 may be implemented in hardware as control module 150-1, such as being implemented as part of the one or more processors 152. The control module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the control module 150 may be implemented as control module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the IAB node 170 to perform one or more of the operations as described herein. Note that the functionality of the control module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

The one or more network interfaces 161 communicate over a network such as via the

links

176 and 131. Two or more IAB nodes 170, 170-1 communicate using, e.g., link 176. The link 176 may be wireless and may implement, e.g., a NR Uu interface.

The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the IAB node 170 possibly being physically in a different location from the RRH/DU, and the one or more buses 157 could be implemented in part as, e.g., fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU) , gNB-CU) of the IAB node 170 to the RRH/DU 195. Reference 198 also indicates those suitable network link (s) .

The IAB node 170-1 includes a DU 195-1 and an MT 70. These are described in more detail below. The DU 195-1 and MT 70 may be implemented as hardware or software or some combination of these. That is, for ease of reference only the CU 196 is shown with processor (s) 152 and memory (ies) 155. However, any DU or MT may also have this circuitry. Note that only one IAB node 170-1 is illustrated, but there can be two or more of these (as shown below) , and the term “170-x” (where x = 1, 2, 3, …) is used below to indicate any one of these.

The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a data network 191, such as a telephone network and/or a data communications network (e.g., the Internet) . Such core network functionality for 5G may include access and mobility management function (s) (AMF (s) ) and/or user plane functions (UPF (s) ) and/or session management function (s) (SMF (s) ) . Such core network functionality for LTE may include MME (Mobility Management Entity) /SGW (Serving Gateway) functionality. These are merely exemplary functions that may be supported by the network element (s) 190, and note that both 5G and LTE functions might be supported. The IAB node 170 is coupled via a link 131 to a network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an S1 interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N/W I/F (s) ) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the network element 190 to perform one or more operations.

The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and

memories

155 and 171, and also such virtualized entities create technical effects.

The computer

readable memories

125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer

readable memories

125, 155, and 171 may be means for performing storage functions. The

processors

120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The

processors

120, 152, and 175 may be means for performing functions, such as controlling the UE 110, IAB node 170, and other functions as described herein.

In general, the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, vehicles with a modem device for wireless V2X (vehicle-to-everything) communication, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances (including Internet of Things, IoT, devices) permitting wireless Internet access and possibly browsing, IoT devices with sensors and/or actuators for automation applications with wireless communication tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

Having thus introduced one suitable but non-limiting technical context for the practice of the exemplary embodiments, the exemplary embodiments will now be described with greater specificity.

As previously described, thanks to the IAB feature, it is possible to relay user traffic over the wireless interface (Uu) (e.g., link 176 in FIG. 1) between two relaying nodes called IAB nodes 170, 170-1. The relaying may take place over one or multiple hops. An overall IAB architecture is presented in FIG. 2. FIG. 2 illustrates an overall IAB architecture, where FIG. 2A illustrates IAB-node configuration using CA mode with NGC, and FIG. 2B illustrates IAB-node configuration using EN-DC. The source for this figure is 3GPP TS 38.300 V16.2.0 (2020-07) , see Figure 4.7.1-1.

In FIG. 2A, there are two AMFs/UPFs 190-1 and 190-2, a gNB 210, an IAB donor node (e.g., a gNB) 170 and two IAB nodes 170-1, 170-2. The interfaces NG, Xn, NR Uu and F1 are shown. In FIG. 2B, there are two MMEs/S-PGWs 190-3 and 190-4, an eNB 220, an eNB that is an MeNB, an IAB donor node (e.g., a SgNB) 170 and two IAB nodes 170-1, 170-2. The interfaces S1, X2, S1-U, X2-C, LTE Uu, NR Uu and F1 are shown.

There are two types of nodes in IAB architecture –IAB-donor 170 and IAB-node 170-1. An IAB donor node 170 is a node, which has a wired connection to the core network. IAB-donor 170 comprises donor-CU 196 part, hosting RRC, SDAP and PDCP layers of NR air interface, and a donor-DU 195 part, hosting RLC, MAC and PHY layer of NR air interface stack. An IAB node 170-1 on the other hand, consists of IAB-DU 195-1 and IAB-MT 70 parts, where IAB DU 195 connects to the donor-CU 196 part using an F1 interface and provides wireless connectivity for access UEs 110 and for IAB-MTs 70 of child or other next-hop IAB nodes 170-1, i.e. those served by the IAB-DU, while IAB-MT 70 is responsible for providing wireless backhaul connectivity to an upstream IAB node 170-x or IAB-donor 170, or may have also other than a backhaul connection, e.g., a PDU session for OAM (Operations and Maintenance) traffic. In IAB, a downstream node connected to an IAB node is called its child node. The upstream node of an IAB node is called its parent node. IAB nodes can be connected to up to two parents simultaneously using NR dual connectivity mode in order to provide topological redundancy to the backhaul link. Those dependencies are presented in FIG. 3.

FIG. 3 illustrates parent-node and child-node relationship for IAB nodes. The source for this figure is 3GPP TS 38.300 V16.2.0 (2020-07) , see Figure 4.7.1-2. In this example, the

parent nodes

170A and 170B include IAB-

DUs

195A and 195B. The IAB node 170-1 includes an IAB-MT 70 and an IAB-DU 195-1. The

parent nodes

170A and 170B are upstream relative to the IAB node 170-1, and the child nodes 170-2A, 170-2B, and 170-2C are downstream. The child nodes 170-2A, 170-2B, and 170-2C include corresponding IAB-MTs 70-1A, 70-1B, and 70-1C. The interfaces between these nodes are the NR Uu interface.

To enable wireless backhaul, a new protocol layer was also introduced in the air interface between IAB-donor DU and IAB node and between two IAB nodes, called Backhaul Adaptation Protocol (BAP) . The protocol stack, for user plane and control plane data carried over a two-hop IAB chain, is presented in FIG. 4. The source for this figure is 3GPP TS 38.300, and FIG. 4 illustrates protocol stacks for the support of F1-U protocol (left-hand side) and F1-C Protocol (right-hand side) .

In this example, the IAB donor 170 has a CU 196 with layers GTP-U and UDP, and has a DU 195 with layers IP, BAP, RLC, MAC, and PHY. In the stacks that are shown, the lowest layer is the PHY (physical) layer, and the highest layer is the GTP-U layer. There is aa BH NR RLC channel between the IAB donor 170 and the IAB node 1 170-1. In FIG. 4, the F1-U interface is between IAB-donor 170 and IAB-node 2 170-2. This is transparent and just relayed by the IAB-node 1 170-1. In the FIG. 4, there is also F1-U terminated in IAB-node 1 but not shown in the figure. The IAB node 1 170-1 has an IAB-MT 70 having layers BAP, RLC, MAC, and PHY, and an IAB-DU 195-1 having layers BAP, RLC, MAC, and PHY. There is an F1-U interface and a BH NR RLC channel between the IAB node 1 170-1 and the IAB node 2 170-2. The F1-U interface terminates in the IAB-DU 195-2 of the IAB node 2 170-2, which has layers of GTP-U, UDP, and IP. The BH NR RLC channel terminates at the IAB-MT 70-1, which includes layers BAP, RLC, MAC, and PHY.

BAP is responsible for mapping upper layers traffic (F1-U, F1-C or non-F1 traffic) onto BH RLC channels using the channel mapping configuration which is provided to the IAB node and IAB-donor DU using F1AP and/or RRC protocol. Traffic is mapped based on the information included in the headers of higher layer protocols such as IP or GTP-U. A specific mapping is configured:

1) for each F1-U GTP-U tunnel;

2) for non-UE associated F1AP messages;

3) for UE-associated F1AP messages of each UE; and

4) for non-F1 traffic.

Another responsibility of BAP is to determine the destination node of the higher layer’s packet and to route the BAP packet within IAB network based on the BAP address and BAP path identifier carried within BAP header and routing configuration provided with F1AP protocol. The BAP header is generated in an IAB node 170-x (where “x” is 1 or 2 in this example) where the traffic originates (for upstream traffic) and in IAB-donor DU 195 for downstream traffic. When the BAP packet arrives at an IAB node 170-x, the node checks the BAP address included in the BAP header to determine whether the address matches its own BAP address, configured earlier by the Donor CU 196. If it does, it is provided to higher layer in the IAB node for further processing. Otherwise, the IAB node 170-x checks its routing table and BH RLC channel mapping configuration to determine the link and the BH RLC channel, where the BAP packet should be routed. An example of this operation is presented in FIG. 5.

FIG. 5 illustrates routing and BH RLC channel selection on BAP sublayer. The source for this is 3GPP TS 38.300. The routing from the prior hop is performed to the next hops by selection of the BH RLC channel. The ingress BH link and ingress BH RLC channels are illustrated, as are the egress BH link and egress BH RLC channels.

Initial IAB networks are expected to be deployed in a controlled and planned manner, such as the following:

1) Fixed positions of IAB nodes;

2) Thorough network and radio planning before deployment;

3) Usage of directional antennas; and/or

4) Line of sight insurance.

In such deployments, BH links are much more reliable than access radio links between the UE and the IAB node. The BH network can additionally be protected via path redundancy, i.e., in case a BH link fails, the BH traffic can be routed via another BH link or IAB network segment. For the access UE on the other hand, one of the methods to increase traffic reliability is usage of PDCP packet duplication, such as the following:

1) Carrier Aggregation (CA) duplication, where the same packet is sent over different cells of the same gNB;

2) Dual Connectivity (DC) duplication, where the same packet is sent over cells belonging to two different gNBs;

3) In Rel-15, duplication over two cells is possible while Rel-16 allows duplication over up to four cells; and/or

4) CA duplication can be configured together with DC duplication in Rel-16.

Packet duplication is presented in 3GPP TS 38.300 section 16.1.3.

When PDCP duplication is configured for radio bearer of the UE, separate GTP-U tunnels are established for each RLC channel involved in duplication. This means data is duplicated not only over the air interface, but also over F1 or Xn interface in the RAN network. While the duplication is justified for the UE’s access link, for example, in fixed IAB deployments, it is not required on the BH links, which for fixed IAB networks are believed by the inventors to be reliable and do not require duplication. Therefore, duplicating packets over BH links brings small benefits while decreasing the resource efficiency and capacity of the network. This may also cause the Donor-DU 195 and the IAB node 170-1 close to the Donor-DU 195 to be bottleneck for the IAB system. This issue is presented in FIG. 6 for two different scenarios.

Scenario 1 610 involves CA duplication between a single IAB node 170-2 and the UE 110. The donor CU 196, donor DU 195, IAB node #1 170-1 and IAB node #2 170-2 are illustrated, and CA duplication 620, which is performed over

wireless links

613 and 614, is illustrated. The waste of resources 650 occurs because the dashed 611 and solid 612 lines indicate two paths, each carrying the same data. The path 611 is for a first GTP-U #1 path, and the path 612 is for a second GTP-U #2 path.

Paths

611 and 612 carry the same user data over the BH link. The duplication and the GPT tunnels are terminated at the access IAB-node 170-2. Over the Uu interface (via links 613 and 614) , there are two RLC/MAC/PHY connections over the CA carriers while PDCP are end-to-end between UE 110 and IAB-donor node 196. In reality, only the IAB #2 170-2 needs to perform the duplication, using the

wireless links

613 and 614, if the

other paths

611 and 612 are assumed to be error-free or low error. Similar issue also applies to uplink when the UE send the uplink data to donor CU 196 via the access node (IAB #2 170-2) , the intermediate IAB node (IAB #1 170-1) and donor DU 195. The wireless links 613 and 614 may be for a primary cell (PCell) and a secondary cell (SCell) , respectively, in an example.

Scenario 2 630 involves DC duplication between two IAB nodes (170-2A and 170-2B) and the UE 110. The donor CU 196, donor DU 195, IAB node #1 170-1 and IAB nodes #2 170-2A and 170-2B are illustrated, and DC duplication 640, which is performed using

wireless links

613 and 614, is illustrated. The waste of resources 650 occurs because the dashed 611 and solid 612 lines indicate two paths, each carrying the same data. The path 612 is for a first GTP-U #1 path, and the path 611 is for a second GTP-U #2 path. Only the IAB #1 170-1 needs to perform the duplication, using its

paths

616, 617, which the IAB nodes #2 170-2A and #3 170-2B will send via

wireless links

613 and 614, respectively. This again assumes the

other paths

611 and 612 are error-free or low error. Similar issue also applies to uplink when the UE send the uplink data to donor CU 196 via the access node (IAB #2 170-2, IAB #3 170-2B) , the intermediate IAB node (IAB #1 170-1) and donor DU 195. The wireless links 613 and 614 may be for a primary secondary cell (PSCell) , and a primary cell (PCell) , respectively, in an example.

For non-IAB duplication operation, it was proposed previously that a single GTP-U tunnel should be used on the Xn interface between Master Node and Secondary Node, which are involved in duplication. The proposal has not been adopted in the 3GPP standard. It should be noted that in case of IAB, the previously proposed technique cannot be directly reused, as additional mechanisms are required for duplication and duplicate discarding in the IAB nodes. Also, the issue is much more relevant for the IAB, as the traffic is duplicated on the air interface with very scarce radio resources. For the non-IAB use case, for which this was previously discussed, the issue is less severe as, within the RAN network, the traffic is duplicated only on the wired interfaces, which are usually of high capacity.

It is proposed herein to address this issue, in addition to the other issues outlined above and other issues, by introducing a mechanism to avoid unnecessary duplicate packets in the IAB node 170-x or IAB-donor DU 195, before carrying the packets on the backhaul links where this is unnecessary, while still allowing the packets to be duplicated in the necessary IAB network nodes and over the air interface. First, an overview is provided, then additional details are provided.

In exemplary embodiments, and as an overview, the mechanism is based on the following.

1) The Donor CU 196 provides a “duplication configuration” for a radio bearer (RB) of the UE, for which the packet duplication is enabled. The configuration information is provided using one of the below options (a) to (c) .

a) Within backhaul configuration of the IAB-donor DU (for DL traffic) and/or access IAB node (for UL traffic) . After receiving such configuration, IAB-donor DU or IAB node adds duplication indication to the BAP header of the packets related to the duplicated radio bearer. It is noted that the “access” IAB node is the node to which the UE is attached. The IAB node may be an access IAB node for some UEs and a regular BH IAB node for other UEs that are not directly attached to the IAB node, but through child IAB nodes. For access IAB node, this may also be performed within an F1-U tunnel configuration or as part of UE radio bearer configuration. When the F1-C packet need to be duplicated, the configuration in the access IAB node may be performed during the gNB-DU configuration update procedure or gNB-CU configuration update procedure.

b) By indicating the BH RLC channel carrying the traffic, which should be duplicated for the access UE. In this situation, the IAB-donor DU 195 and/or the IAB node 170-x identifies that a packet belongs to the duplicated radio bearer based on this packet’s ingress or egress BH RLC channel.

Based on the configuration, the IAB network node (donor DU, or IAB node) detects the related traffic and add the duplication indication.

In the DL direction, the indication could additionally include information about the number of copies required and/or which access logical channels should be used for packet delivery to the UE.

2) Based on the duplication indication, an IAB node performs the following.

a) In the DL direction, when receiving the packet marked with duplication indication (carried, e.g., either in the BAP header or deduced based on its ingress BH RLC channel) , the IAB node 170-x or IAB-MT 70-x function of the IAB node 170-x, indicates that a packet should be duplicated over the air interface to the functions responsible for packet delivery to the UE (e.g., to upper layers in the IAB node or the transmission part of the BAP sub-layer, or the like) . After having received such indication, the IAB node 170-x (or an IAB-DU 195-x function of the IAB node 170-x) duplicates the packets over the air interface.

b) In the UL direction, in response to receiving a packet over the radio bearer configured with duplication, or marked with duplication indication based on previous configuration, the IAB node 170-x performs a duplicate discard function, which normally is only performed in the PDCP layer hosted by the donor CU 196.

Additionally, the discard function can be performed based on PDCP Sequence Number (SN) of the packet, meaning that the IAB node needs to have basic PDCP functionality such as a PDCP duplicate discard function and PDCP window functions. The discard function will remember the received SN of PDCP. But when all PDCP SN have been used, the PDCP layer will reuse the SN starting from 0 (zero) , and the PDCP layer uses a window to be sure that there is no confusion. This window should be used in the IAB node to know where the current SN is in the PDCP SN window.

Duplication related functions could reside in either IAB-MT or IAB-DU. Consider the following. For UL, it makes more sense to detect and discard duplicates in IAB-DU, once they are received for the UE. For DL, the Rx part of BAP layer could indicate to upper layers about the need to duplicate and upper layers would handle that (by upper layers, it is meant upper layers in the IAB-DU) .

Now that an overview has been provided, additional details are provided. In a first embodiment, a UE configured with CA based duplication. FIG. 7 depicts an exemplary implementation where a duplication handling function 710 is introduced in the access IAB node 170-2 to handle an access UE radio bearer configured with a CA-based duplication. This figure also illustrates a PCell (primary cell) 730 and an SCell (secondary cell) 720 formed by the IAB 2 170-2. Note that each of the PCell 730 and SCell 720 has its own RLC and MAC layers, which are used to perform packet duplication in CA examples. The layers and other blocks in the elements in FIG. 7 may be means for performing those corresponding functions and may be implemented in hardware or software, as described above with respect to the processors and memories for each of the UE 110 and IAB donor node 170 and IAB node 170-x.

For traffic sent in the DL direction, the following exemplary alternatives are proposed.

1) In a first alternative:

a) The donor CU 196 configures to the donor DU 195 that a certain traffic flow, identified, e.g., by a certain IP header contents, e.g., IP address and/or port number and/or Differentiated Services Code Point (DSCP) and/or IPv6 flow label etc., is to be duplicated for the UE.The donor CU 196 may also configure to the donor DU 195 that a certain traffic flow, identified, e.g., by a certain GTP-U header contents, e.g. GTP-U tunnel endpoint identifier, is to be duplicated for the UE.

b) Later, when the donor DU 195 receives the downlink data from donor CU 196, the DU checks the IP header content and/or the GTP-U header content with the previously received configuration. In case matches, donor CU 196 includes a “duplication indication” in the BAP header for packets related to this flow. An indication could additionally include information about the number of copies required and/or which access logical channels should be used for packet delivery to the UE.

c) When such BAP PDU arrives at the destination IAB node, BAP layer indicates to upper layers that a packet should be duplicated over the air interface.

d) The duplicate handling function 710 in the IAB node 170-2 ensures that the BAP SDU is duplicated and provided for transmission to multiple logical channels based on the configuration.

2) In a second alternative:

a) The donor CU 196 configures a certain BH RLC channel or certain traffic of a specific BH RLC channel, identified by at least one of a backhaul radio link control channel identity, a routing identification, a tunnel endpoint identifier, or any field of a backhaul adaptation protocol header, and the like, at the destination IAB node 170-2 with a duplication indication. The donor DU 195 in this case maps incoming packets to RLC channels according to CU’s instructions as usual.

b) The duplicate handling function 710 at the IAB node 170-2 ensures every packet arriving on a certain BH RLC channel is duplicated over the air interface.

c) The indication could be passed to upper layers via the BAP sublayer or could be left to IAB node implementation.

For traffic sent in the UL direction, the following is one possible implementation.

1) Similarly as for DL, the IAB node 170-2 is configured with information from the donor CU 196 that a certain UE DRB is configured with duplication. Such configuration can be part of BH traffic mapping configuration, or part of F1 tunnel configuration for radio bearer configuration, e.g., during the F1AP UE Context Setup/Modification procedure for the UE.

2) The UE 110 sends data to the access IAB node 170-2 using two or more RLC entities /logical channels.

3) IAB node 170-1 checks the identification, for example, PDCP SN, of packets belonging to the duplicated traffic flow and discards a PDCP PDU in case the packet with such SN was received earlier. With this, only one copy of the user data is sent to IAB #1 170-1, and further sent to donor CU 196. This merges the two traffic flows from the UE into a single uplink traffic flow having information from only one of the traffic flows from the UE.

An exemplary flow chart for the first embodiment is presented in FIG. 8. This figure further illustrates the operation of an exemplary method or methods, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments. The operations in FIG. 8 are assumed to be performed by the UE 110 under control of the control module 140 at least in part, or performed by an IAB network node 170 or 170-x under control of the control module 150 at least in part.

In step 1 of FIG. 8, there is a DRB establishment with CA PDCP duplication. This is between the UE 110 and the IAB node 2 170-2, then also between the IAB node 2 170-2 and the donor CU 196, via the IAB node 1 170-1 and the donor DU 195. The donor CU 196 transmits in step 2 to the donor DU 195 messaging including backhaul mapping configuration for a DL traffic flow, with duplication indication. The donor CU 196 also sends the messaging in step 3 to the IAB node 170-2 to configure the duplication.

Block 810 indicates the signaling that occurs for handling of duplicated DRB in DL. Block 820 indicates the signaling that occurs for handling of duplicated DRB in UL. Block 810 is described first.

In block 810, the donor CU 196 sends (step 4) a message including DL user data of a duplicated DRB. The donor DU 195 detects the user data need to be duplicated based the configuration received in step 2. The donor DU 195 adds (step 5) a duplication indication to the BAP header (in this example) based on a BH mapping configuration. This conforms to the first alternative above, where the donor DU 195 includes a “duplication indication” in the BAP header for packets related to this flow.

The donor DU 195 performs (step 6) a BAP PDU delivery with indication for IAB node 2, via the intermediate IAB node (for example IAB node #1 170-1) . That is, this delivery terminates at the IAB node 170-2. In the carrier aggregation case, it is always the access IAB node that performs the duplication, so the intermediate IAB node has not received any instructions from the CU about the duplication and the BAP header does not indicate that the intermediate node should duplicate. In this case, the access IAB node is the IAB node 2 170-2. The IAB node 170-2 performs (step 7) detection of the duplication indication in the BAP header, and then performs (step 8) providing the duplication indication to upper layers.

Steps

7 and 8 are performed by the duplicate handling function 710, which sends the duplication indication to at least the RLC layers in the PCell 730 and SCell 720. The RLC layers then determine that the packets involved for this DRB are being duplicated and perform known duplication processes. The IAB node 170-2 performs packet delivery using the PCell 730 in step 9, and performs packet duplicate delivery using the SCell 720 in step 10. The UE discards the packet if the packet has already been successfully received via the other path. The UE behavior is not affected for these operations, as per the examples herein.

For block 820, which indicates the signaling that occurs for handling of duplicated DRB in UL, the UE 110 is in a CA mode. Therefore, the UE sends an UL packet on the primary RLC channel of a duplicated DRB, e.g., via the PCell 730. This occurs in step 11. In step 12, the UE sends the same UL packet on the secondary RLC channel of a duplicated DRB, e.g., via the SCell 720. The duplication is for PDCP packets sent to RLC channels on different carriers (in the CA case) . The PDCP packet is sent over the primary link and duplicate one is sent over the second link –or vice versa.

Steps 13-15 may be performed by the duplicate handling function 710. In step 13, the duplicate handling function 710 performs a duplicate detection function, and in step 14, discards a duplicate packet. As described above, IAB node 170-2 (e.g., via the duplicate handling function 710) checks the PDCP SN of packets belonging to the duplicated traffic flow and discards a PDCP PDU in case the packet with such SN was received earlier. The remaining, single packet is delivered to upper layers, e.g., BAP, for transmission (step 15) . See step 16. This means that duplicate traffic flows from the UE are merged into a single traffic flow.

In a second embodiment, the UE is configured with DC-based duplication. In case the access UE is configured with DC-based duplication, the duplicate handling function has to reside in one of the intermediate IAB nodes. In the example of FIG. 9, this is IAB node 170-1, for this particular configuration of three IAB node 170-1, 2, and 3. This is merely exemplary, however. This case is presented in FIG. 9. This figure also illustrates a PCell (primary cell) 930 formed by IAB node 170-2 and an PSCell (primary secondary cell) 920 formed by the IAB 2 170-3. Note that each of the PCell 930 (for IAB node 170-2) and PSCell 920 (for IAB node 170-3) has its own RLC and MAC layers, which are used to perform packet duplication in DC examples. The layers and other blocks in the elements in FIG. 9 may be means for performing those corresponding functions and may be implemented in hardware or software, as described above with respect to the processors and memories for each of the UE 110 and IAB donor node 170 and IAB nodes 170-2/170-3. The method as described below also applies when the UE 110 directly connects with IAB 170-1 without IAB 170-2, or without IAB 170-3. When IAB 170-2 is absent and IAB 170-3 is present, the PCell (primary cell) 930 formed by IAB node 170-1 and an PSCell (primary secondary cell) 920 formed by the IAB 170-3. When IAB 170-2 is present and IAB 170-3 is absent, the PCell (primary cell) 930 may be formed by IAB node 170-2 and a PSCell (primary secondary cell) 920 may be formed by the IAB 170-1.

For traffic sent in DL direction, the following is one possible implementation.

1) There is no need to duplicate the packets over the BH links, which are common for the paths between each of the IAB nodes 170-2/170-3 involved in DC duplication.

a) The packet needs only to be duplicated by the last node common (IAB node 1 170-1 in the presented example) for both paths.

b) The donor CU 196 knows the topology so knows also the IAB node 170-1 which should duplicate the packet. The donor CU 196 configures to the donor DU 195 that a certain traffic flow, identified, e.g., by a certain IP header contents, e.g., IP address and/or port number and/or Differentiated Services Code Point (DSCP) and/or IPv6 flow label, or the like, is to be duplicated for the UE. The donor CU 196 may also configure to the donor DU 195 that a certain traffic flow, identified, e.g., by a certain GTP-U header contents, e.g. GTP-U tunnel endpoint identifier, is to be duplicated for the UE. The donor CU 196 configures the donor DU 195 to add the duplication indication, and configures IAB node 170-1 to perform the duplication based on the duplication indication. That is, in an exemplary embodiment, the donor CU 196 configures the IAB node 170-1 to enable the duplication using a duplication indication, and then the IAB node 170-1 performs duplication when data arrives having the duplication indication.

2) A duplication indication (added by the donor DU 195, which is the first BAP node in DL direction) can be carried in a BAP header similarly as in the CA case. However, for the DC case, BAP should also indicate the IAB node which should perform duplication of the packets:

a) An address of the IAB node 170-x (in the example of FIG. 9, IAB node 170-1) to perform duplication can be carried in the BAP header (e.g., as added by the donor DU, per the configuration from the donor CU) in addition to the BAP address of the destination IAB node. Alternatively, there may be no change to the BAP header, but the donor CU 196 configures this IAB node to perform the duplication for specific BAP PDUs, e.g., when performing the configuration in step (b) below. In this alternative, nothing is added to regular BAP header, and the donor DU just sets the path ID according to CU’s instructions.

b) A special path ID (identification) or an indication can be configured in the IAB node, the path ID or the indication indicating that the BAP PDU is to be duplicated with additional information about which links are to be used for transmission. In this example, CU configures this to the IAB node who does the duplication. Donor DU only sets the path ID according to CU’s configuration as usual. This can be achieved with configuring the IAB node with two routing entries for the same routing ID, optionally with an “duplication indication” . The routing ID typically comprises the BAP address and the path ID. In this case the path ID part of the routing ID indicates that the packet should be duplicated, and there would be two BAP addresses in the BAP header. In this example, the routing ID has a BAP address of the destination node (170-2A or B) , but there is an additional BAP address indicating the node (170-1) that performs the duplication.

c) The IAB node 170-1 may also be configured to modify the routing IDs in the BAP header before forwarding the packet further. In other words, since duplicates are heading to different end IAB nodes, the BAP address of the packet may be modified accordingly. The CU 196 may configure the IAB node 170-1, or the IAB node 170-1 may be preconfigured to decide to modify header by itself, since the duplicates are sent to different destination IAB nodes 170-2/3. The duplication indication may be carried in the BAP header. If so, the donor DU adds the indication.

d) Since the packets received by the two final IAB nodes IAB node 170-2 and 170-3 would contain the same IP packet (same IP address, and the like) , IP nodes need to be configured in such a way that a respective IP packet is not discarded by any of them.

For traffic sent in UL direction, the following is one possible implementation:

1) Similarly as in CA case, the duplicates should be discarded by the IAB node, in this case it would be the first common node 170-1 for duplicated packet’s UL path. That is, the common node is IAB 1 170-1 in the depicted case.

2) In order for the IAB node 170-1 to recognize the duplicates, the following is performed:

a) Similarly as in the CA case, the IAB node (e.g., IAB 1 170-1) is configured (e.g., by the donor CU 196) with information about which BH RLC Channels and/or Routing IDs and/or GTP-U TEID are used for carrying duplicated packets. Since there may be multiple GTP-U tunnels sharing the same BH RLC Channel/Routing ID between access IAB and Donor-CU, IAB 1 170-1 may be provided with additional info, e.g., TEID, to identify the related UL traffic.

b) In case IPsec is not configured, the IAB node 170-1 can peek into BAP SDU, read its PDCP SN, check whether the packet with the same PDCP SN of this radio bearer was already transmitted earlier and, if it was, discard such duplicate packet.

c) In case encryption is enabled for the F1 tunnel carrying the duplicated bearer:

i) There is no possibility for IAB node to check PDCP SN directly in the PDCP PDU.

ii) To handle this issue, the access IAB node handling logical channels configured for a duplicate radio bearer (e.g., IAB 2 170-2 and IAB 3 170-3 in the depicted case) replicates the GTP-U TEID and PDCP SN into the BAP header. If there is a need to consider the F1-C, access IAB node 170-2/3 replicates the SCTP Stream Identifier and Stream Sequence number into BAP header. Alternatively, the F1 tunnel could be terminated in the intermediate node (in this case, IAB node 170-1) handling the duplication functions.

The duplicate handling function 910 merges duplicate traffic flows from the UE into a single traffic flow. That is, only a single traffic flow (e.g., individual packets created using the duplicate packets received via the IAB nodes 170-2 and 170-3) is sent to parent nodes by the IAB node 170-1.

It should also be noted that current F1-U security is peer-to-peer, i.e., one transmitter ciphers the GTP-U, and one receiver deciphers the received GTP-U packet. In the presented case, the DL F1-U is with destination set to IAB 2 170-2, and is ciphered with the IAB 2-CU security key. Even though IAB 1 170-1 can duplicate the DL F1-U and send to IAB 3 170-3, IAB 3 cannot decipher the DL F1-U packet that is ciphered using IAB 2’s key. A security mechanism similar as in MBMS can be used, so that both IAB 2 and IAB 3 can decipher the DL F1-U packet.

Now that the first and second exemplary embodiments have been illustrated, an example is related of the potential implementation of a duplicate discard function such as duplicate handling function 710/910.

In UL, a simple pushed-based window handling and discarding function can be implemented in the node in charge of the duplication avoidance. As the node does not know the HFN of the PDCP packet, the node can rely on the SN of the packet. The node should also know the window size of the PDCP entity for the DRB. The node has a variable RX_Next_SN, initialized to 0 (zero) .

When a PDCP packet is received with a given RCV_SN, the calculations are made modulo Window_size*2, where window size is the reception window of the PDCP entity for this DRB. The following process may be performed, illustrated in pseudocode.

1>If RX_Next_SN<= RCV_SN < RX_Next_SN + Window_size:

2>If a PDCP with same SN has been received already, then discard the packet; Else, transmit the packet and store the status SN= RCV_SN;

2>Set RX_Next_SN to RCV_SN +1 and reset the received status for the SN between RX_Next_SN and RCV_SN;

1>Else: discard the packet (this should not happen if the PCDP packet are sent within the Window_size) .

The following are additional examples.

Example 1. A method, comprising:

in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following:

receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction;

in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and

in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.

Example 2. The method of example 1, wherein:

the integrated access and backhaul network node is connected via carrier aggregation with the user equipment; and

the transmitting the multiple traffic flows toward the user equipment and the receiving second data over multiple traffic flows from the user equipment are performed by the integrated access and backhaul network node using the carrier aggregation.

Example 3. The method of example 1, wherein:

the integrated access and backhaul network node is connected via dual connectivity to the user equipment, via a wireless link between the integrated access and backhaul network node and the user equipment and via a second backhaul link between the integrated access and backhaul network node, as a parent node, and one other integrated access and backhaul network node that is a child node to the parent node;

the transmitting the multiple downlink traffic flows toward the user equipment comprises transmitting respective ones of the multiple downlink traffic flows via the wireless link and the second backhaul link; and

the receiving second data over multiple uplink traffic flows from the user equipment further comprises receiving the second data via the wireless link and the second backhaul link.

Example 4. The method of example 1, wherein:

the integrated access and backhaul network node, as a parent node, is connected to two integrated access and backhaul nodes, as child nodes, providing dual connectivity to the user equipment;

the transmitting the multiple downlink traffic flows toward the user equipment comprises transmitting respective ones of the multiple downlink traffic flows via second backhaul links to respective ones of the child nodes; and

the receiving second data over multiple uplink traffic flows from the user equipment further comprises receiving the second data via the second backhaul links from respective ones of the child nodes.

Example 5. The method of either examples 1 to 4, wherein:

determining the first data is indicated as to be duplicated further comprises determining for data received over the backhaul link that the data has an associated duplication indication and means the data is first data that should be duplicated; and

performing the duplicating only for the first data determined to have the associated duplication indication.

Example 6. The method of any one of examples 1 to 5, further comprising determining the first data is indicated to be duplicated in the downlink direction or the second data is indicated as to be merged based on at least one of following:

a duplication indication;

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.

Example 7. The method of any one of examples 1 to 6, further comprising receiving the configuration to identify duplication or merging from an integrated access and backhaul donor node, the configuration including one or more of following:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.

Example 8. The method of example 1, wherein the determining the second data is indicated as data to be merged comprises examining backhaul adaptation protocol headers of the second data to determine whether at least one of a tunnel endpoint identifier or a packet data convergence protocol sequence number indicates the second data should be merged or whether at least one of a stream control transmission protocol stream identifier or stream sequence number indicates the second data should be merged.

Example 9. The method of any one of examples 1 to 8, wherein the integrated access and backhaul network node is an integrated access and backhaul node.

Example 10. The method of any one of examples 1 to 8, wherein the integrated access and backhaul network node is an integrated access and backhaul donor distributed unit node.

Example 11. A method, comprising:

receiving data for a user equipment at an integrated access and backhaul donor distributed unit node;

determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated;

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and

forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.

Example 12. The method of example 11, wherein the determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated comprises receiving, from an integrated access and backhaul central unit node, configuration information that a certain traffic flow is to be duplicated for the user equipment, and the data is part of the certain traffic flow.

Example 13. The method of example 12, wherein the configuration information comprises certain Internet protocol header content indicating that the certain traffic flow is to be duplicated for the user equipment.

Example 14. The method of any one of examples 11 to 12, wherein the duplication indication comprises a duplication indication in backhaul adaptation protocol headers for packets related to this certain traffic flow.

Example 15. The method of any one of examples 11 to 14, wherein the integrated access and backhaul node is an access node for the user equipment using transmission via multiple wireless links in carrier aggregation to the user equipment.

Example 16. The method of example 15, wherein adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data further comprises including a duplication indication in a backhaul adaptation protocol header for packets related to a traffic flow to be duplicated.

Example 17. The method of example 16, wherein the duplication indication in the backhaul adaptation protocol header comprises information about a number of copies required and/or which access logical channels should be used for packet delivery to the user equipment.

Example 18. The method of any one of examples 11 to 14, wherein the integrated access and backhaul node uses transmission via multiple backhaul links in dual connectivity from at least one integrated access and backhaul child node to the user equipment, wherein the integrated access and backhaul node is a parent node to the at least one integrated access and backhaul child nodes.

Example 19. The method of example 15, wherein:

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data further comprises including a duplication indication in a backhaul adaptation protocol header for packets related to a traffic flow to be duplicated; and

the method includes the integrated access and backhaul donor distributed unit node indicating the integrated access and backhaul node that should perform duplication of the data.

Example 20. The method of example 19, wherein the indicating the integrated access and backhaul node that should perform duplication of the data is performed by including an address of the integrated access and backhaul node in the backhaul adaptation protocol header.

Example 21. The method of example 19, wherein the indicating the integrated access and backhaul node that should perform duplication of the data is performed by adding a path identification and a backhaul adaptation protocol address to the data, the path identification indicating the packet should be duplicated and the backhaul adaptation protocol address indicating an address of the integrated access and backhaul node to perform the duplicating.

Example 22. A method, comprising:

at an integrated access and backhaul donor control unit in a network, performing the following:

determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and

configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.

Example 23. The method of example 22, wherein the integrated access and backhaul network node is an integrated access and backhaul donor distributed unit node, and wherein the information comprises at least one of the following information for a traffic flow in the downlink direction:

an Internet protocol address;

a Differentiated Services Code Point value;

a flow label;

a field of Internet protocol header; or

a tunnel endpoint identifier.

Example 24. The method of example 23, wherein the information that traffic flow in an uplink direction for the user equipment is to be merged also indicates to the integrated access and backhaul donor distributed unit node that multiple traffic flows in the uplink direction for the user equipment are to be merged into a single traffic flow, and wherein the information comprises at least one of the following information for a traffic flow in the uplink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.

Example 25. The method of example 22, wherein:

the integrated access and backhaul network node is an integrated access and backhaul node;

the information that traffic flow in a downlink direction for the user equipment is to be duplicated comprises at least one of the following for a traffic flow in the downlink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header; and

the information that traffic flow in an uplink direction for the user equipment is to be merged comprises at least one of the following for a traffic flow in the uplink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.

Example 26. A computer program, comprising code for performing the methods of any of examples 1 to 25, when the computer program is run on a computer.

Example 27. An apparatus, comprising means for performing the methods of any one of examples 1 to 25.

Example 28. An apparatus, comprising: one or more processors; and one or more memories including computer program code, wherein the one or more memories and the computer program code are configured, with the one or more processors, to cause the apparatus to perform the methods of any one of examples 1 to 25.

Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect and advantage of one or more of the example embodiments disclosed herein is the resource efficiency on the backhaul links is increased. Another technical effect and advantage of one or more of the example embodiments disclosed herein is the IAB network capacity is increased. Another technical effect or of one or more of the example embodiments disclosed herein is at the same time, the extra reliability can still be ensured for the access link thanks to duplication.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) : (i) a combination of analog and/or digital hardware circuit (s) with software/firmware and (ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. ”

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

Embodiments herein may be implemented in software (executed by one or more processors) , hardware (e.g., an application specific integrated circuit) , or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional computer-readable media. In the context of this document, a “computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in FIG. 1. A computer-readable medium may comprise a computer-readable storage medium (e.g.,

memories

125, 155, 171 or other device) that may be any media or means that can contain, store, and/or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals.

If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP third generation partnership project

5G fifth generation

5GC 5G core network

AMF access and mobility management function

BAP Backhaul Adaptation Protocol

BH Backhaul

CA carrier aggregation

CU central unit

DC Dual Connectivity

DL Downlink

DRB data radio bearer

DSCP Differentiated Services Code Point

DU distributed unit

eNB (or eNodeB) evolved Node B (e.g., an LTE base station)

EN-DC E-UTRA-NR dual connectivity

en-gNB or En-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as secondary node in EN-DC

E-UTRA evolved universal terrestrial radio access, i.e., the LTE radio access technology

gNB (or gNodeB) base station for 5G/NR, i.e., a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC

HFN hyper frame number

GPRS General Packet Radio Service

GTP GPRS Tunneling Protocol

GTP-U GTP User Plane

IAB Integrated Access and Backhaul

ID identification

I/F interface

IP Internet protocol

IPsec Internet protocol security

IPv6 Internet protocol version 6

LTE long term evolution

MAC medium access control

MBMS Multimedia Broadcast and Multicast Service

MgNB or MeNB master node, gNB or eNB in this example

MME mobility management entity

MT mobile terminated or mobile termination

ng or NG next generation

ng-eNB or NG-eNB next generation eNB

NR new radio

N/W or NW network

PCell primary cell

PDCP packet data convergence protocol

PDCP SN PDCP Sequence Number

PDU protocol data unit

PHY physical layer

RAN radio access network

Rel release

RLC radio link control

RRH remote radio head

RRC radio resource control

RU radio unit

Rx receiver

SCell secondary cell

SCTP stream control transmission protocol

SDAP service data adaptation protocol

SDU Service Data Unit

SgNB or SeNB secondary node, gNB or eNB

SGW serving gateway

SMF session management function

SN serial number

TEID Tunnel Endpoint Identifier

TS technical specification

Tx transmitter

UE user equipment (e.g., a wireless, typically mobile device)

UL uplink

UPF user plane function

Claims

A method, comprising:

in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following:

receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction;

in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and

in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.
The method of claim 1, wherein:

the integrated access and backhaul network node is connected via carrier aggregation with the user equipment; and

the transmitting the multiple traffic flows toward the user equipment and the receiving second data over multiple traffic flows from the user equipment are performed by the integrated access and backhaul network node using the carrier aggregation.
The method of claim 1, wherein:

the integrated access and backhaul network node is connected via dual connectivity to the user equipment, via a wireless link between the integrated access and backhaul network node and the user equipment and via a second backhaul link between the integrated access and backhaul network node, as a parent node, and one other integrated access and backhaul network node that is a child node to the parent node;

the transmitting the multiple downlink traffic flows toward the user equipment comprises transmitting respective ones of the multiple downlink traffic flows via the wireless link and the second backhaul link; and

the receiving second data over multiple uplink traffic flows from the user equipment further comprises receiving the second data via the wireless link and the second backhaul link.
The method of claim 1, wherein:

the integrated access and backhaul network node, as a parent node, is connected to two integrated access and backhaul nodes, as child nodes, providing dual connectivity to the user equipment;

the transmitting the multiple downlink traffic flows toward the user equipment comprises transmitting respective ones of the multiple downlink traffic flows via second backhaul links to respective ones of the child nodes; and

the receiving second data over multiple uplink traffic flows from the user equipment further comprises receiving the second data via the second backhaul links from respective ones of the child nodes.
The method of either claims 1 to 4, wherein:

determining the first data is indicated as to be duplicated further comprises determining for data received over the backhaul link that the data has an associated duplication indication and means the data is first data that should be duplicated; and

performing the duplicating only for the first data determined to have the associated duplication indication.
The method of any one of claims 1 to 5, further comprising determining the first data is indicated to be duplicated in the downlink direction or the second data is indicated as to be merged based on at least one of following:

a duplication indication;

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The method of any one of claims 1 to 6, further comprising receiving the configuration to identify duplication or merging from an integrated access and backhaul donor node, the configuration including one or more of following:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The method of claim 1, wherein the determining the second data is indicated as data to be merged comprises examining backhaul adaptation protocol headers of the second data to determine whether at least one of a tunnel endpoint identifier or a packet data convergence protocol sequence number indicates the second data should be merged or whether at least one of a stream control transmission protocol stream identifier or stream sequence number indicates the second data should be merged.
The method of any one of claims 1 to 8, wherein the integrated access and backhaul network node is an integrated access and backhaul node.
The method of any one of claims 1 to 8, wherein the integrated access and backhaul network node is an integrated access and backhaul donor distributed unit node.
A method, comprising:

receiving data for a user equipment at an integrated access and backhaul donor distributed unit node;

determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated;

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and

forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.
The method of claim 11, wherein the determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated comprises receiving, from an integrated access and backhaul central unit node, configuration information that a certain traffic flow is to be duplicated for the user equipment, and the data is part of the certain traffic flow.
The method of claim 12, wherein the configuration information comprises certain Internet protocol header content indicating that the certain traffic flow is to be duplicated for the user equipment.
The method of any one of claims 11 to 12, wherein the duplication indication comprises a duplication indication in backhaul adaptation protocol headers for packets related to this certain traffic flow.
The method of any one of claims 11 to 14, wherein the integrated access and backhaul node is an access node for the user equipment using transmission via multiple wireless links in carrier aggregation to the user equipment.
The method of claim 15, wherein adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data further comprises including a duplication indication in a backhaul adaptation protocol header for packets related to a traffic flow to be duplicated.
The method of claim 16, wherein the duplication indication in the backhaul adaptation protocol header comprises information about a number of copies required and/or which access logical channels should be used for packet delivery to the user equipment.
The method of any one of claims 11 to 14, wherein the integrated access and backhaul node uses transmission via multiple backhaul links in dual connectivity from at least one integrated access and backhaul child node to the user equipment, wherein the integrated access and backhaul node is a parent node to the at least one integrated access and backhaul child nodes.
The method of claim 15, wherein:

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data further comprises including a duplication indication in a backhaul adaptation protocol header for packets related to a traffic flow to be duplicated; and

the method includes the integrated access and backhaul donor distributed unit node indicating the integrated access and backhaul node that should perform duplication of the data.
The method of claim 19, wherein the indicating the integrated access and backhaul node that should perform duplication of the data is performed by including an address of the integrated access and backhaul node in the backhaul adaptation protocol header.
The method of claim 19, wherein the indicating the integrated access and backhaul node that should perform duplication of the data is performed by adding a path identification and a backhaul adaptation protocol address to the data, the path identification indicating the packet should be duplicated and the backhaul adaptation protocol address indicating an address of the integrated access and backhaul node to perform the duplicating.
A method, comprising:

at an integrated access and backhaul donor control unit in a network, performing the following:

determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and

configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.
The method of claim 22, wherein the integrated access and backhaul network node is an integrated access and backhaul donor distributed unit node, and wherein the information comprises at least one of the following information for a traffic flow in the downlink direction:

an Internet protocol address;

a Differentiated Services Code Point value;

a flow label;

a field of Internet protocol header; or

a tunnel endpoint identifier.
The method of claim 23, wherein the information that traffic flow in an uplink direction for the user equipment is to be merged also indicates to the integrated access and backhaul donor distributed unit node that multiple traffic flows in the uplink direction for the user equipment are to be merged into a single traffic flow, and wherein the information comprises at least one of the following information for a traffic flow in the uplink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The method of claim 22, wherein:

the integrated access and backhaul network node is an integrated access and backhaul node;

the information that traffic flow in a downlink direction for the user equipment is to be duplicated comprises at least one of the following for a traffic flow in the downlink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header; and

the information that traffic flow in an uplink direction for the user equipment is to be

merged comprises at least one of the following for a traffic flow in the uplink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
A computer program, comprising code for performing the methods of any of claims 1 to 25, when the computer program is run on a computer.
The computer program according to claim 26, wherein the computer program is a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with the computer.
The computer program according to claim 26, wherein the computer program is directly loadable into an internal memory of the computer.
An apparatus, comprising means for performing:

in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following:

receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction;

in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and

in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.
The apparatus of claim 29, wherein:

the integrated access and backhaul network node is connected via carrier aggregation with the user equipment; and

the transmitting the multiple traffic flows toward the user equipment and the receiving second data over multiple traffic flows from the user equipment are performed by the integrated access and backhaul network node using the carrier aggregation.
The apparatus of claim 29, wherein:

the integrated access and backhaul network node is connected via dual connectivity to the user equipment, via a wireless link between the integrated access and backhaul network node and the user equipment and via a second backhaul link between the integrated access and backhaul network node, as a parent node, and one other integrated access and backhaul network node that is a child node to the parent node;

the transmitting the multiple downlink traffic flows toward the user equipment comprises transmitting respective ones of the multiple downlink traffic flows via the wireless link and the second backhaul link; and

the receiving second data over multiple uplink traffic flows from the user equipment further comprises receiving the second data via the wireless link and the second backhaul link.
The apparatus of claim 29, wherein:

the integrated access and backhaul network node, as a parent node, is connected to two integrated access and backhaul nodes, as child nodes, providing dual connectivity to the user equipment;

the transmitting the multiple downlink traffic flows toward the user equipment comprises transmitting respective ones of the multiple downlink traffic flows via second backhaul links to respective ones of the child nodes; and

the receiving second data over multiple uplink traffic flows from the user equipment further comprises receiving the second data via the second backhaul links from respective ones of the child nodes.
The apparatus of either claims 29 to 32, wherein:

determining the first data is indicated as to be duplicated further comprises determining for data received over the backhaul link that the data has an associated duplication indication and means the data is first data that should be duplicated; and

performing the duplicating only for the first data determined to have the associated duplication indication.
The apparatus of any one of claims 29 to 33, further comprising means for determining the first data is indicated to be duplicated in the downlink direction or the second data is indicated as to be merged based on at least one of following:

a duplication indication;

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The apparatus of any one of claims 29 to 34, further comprising means for receiving the configuration to identify duplication or merging from an integrated access and backhaul donor node, the configuration including one or more of following:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The apparatus of claim 29, wherein the determining the second data is indicated as data to be merged comprises examining backhaul adaptation protocol headers of the second data to determine whether at least one of a tunnel endpoint identifier or a packet data convergence protocol sequence number indicates the second data should be merged or whether at least one of a stream control transmission protocol stream identifier or stream sequence number indicates the second data should be merged.
The apparatus of any one of claims 29 to 36, wherein the integrated access and backhaul network node is an integrated access and backhaul node.
The apparatus of any one of claims 29 to 36, wherein the integrated access and backhaul network node is an integrated access and backhaul donor distributed unit node.
An apparatus, comprising means for performing:

receiving data for a user equipment at an integrated access and backhaul donor distributed unit node;

determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated;

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and

forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.
The apparatus of claim 39, wherein the determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated comprises receiving, from an integrated access and backhaul central unit node, configuration information that a certain traffic flow is to be duplicated for the user equipment, and the data is part of the certain traffic flow.
The apparatus of claim 40, wherein the configuration information comprises certain Internet protocol header content indicating that the certain traffic flow is to be duplicated for the user equipment.
The apparatus of any one of claims 39 to 40, wherein the duplication indication comprises a duplication indication in backhaul adaptation protocol headers for packets related to this certain traffic flow.
The apparatus of any one of claims 39 to 42, wherein the integrated access and backhaul node is an access node for the user equipment using transmission via multiple wireless links in carrier aggregation to the user equipment.
The apparatus of claim 43, wherein adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data further comprises including a duplication indication in a backhaul adaptation protocol header for packets related to a traffic flow to be duplicated.
The apparatus of claim 44, wherein the duplication indication in the backhaul adaptation protocol header comprises information about a number of copies required and/or which access logical channels should be used for packet delivery to the user equipment.
The apparatus of any one of claims 39 to 42, wherein the integrated access and backhaul node uses transmission via multiple backhaul links in dual connectivity from at least one integrated access and backhaul child node to the user equipment, wherein the integrated access and backhaul node is a parent node to the at least one integrated access and backhaul child nodes.
The apparatus of claim 43, wherein:

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data further comprises including a duplication indication in a backhaul adaptation protocol header for packets related to a traffic flow to be duplicated; and

the integrated access and backhaul donor distributed unit node includes means for indicating the integrated access and backhaul node that should perform duplication of the data.
The apparatus of claim 48, wherein the indicating the integrated access and backhaul node that should perform duplication of the data is performed by including an address of the integrated access and backhaul node in the backhaul adaptation protocol header.
The apparatus of claim 48, wherein the indicating the integrated access and backhaul node that should perform duplication of the data is performed by adding a path identification and a backhaul adaptation protocol address to the data, the path identification indicating the packet should be duplicated and the backhaul adaptation protocol address indicating an address of the integrated access and backhaul node to perform the duplicating.
An apparatus, comprising means for performing:

at an integrated access and backhaul donor control unit in a network, performing the following:

determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and

configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.
The apparatus of claim 50, wherein the integrated access and backhaul network node is an integrated access and backhaul donor distributed unit node, and wherein the information comprises at least one of the following information for a traffic flow in the downlink direction:

an Internet protocol address;

a Differentiated Services Code Point value;

a flow label;

a field of Internet protocol header; or

a tunnel endpoint identifier.
The apparatus of claim 51, wherein the information that traffic flow in an uplink direction for the user equipment is to be merged also indicates to the integrated access and backhaul donor distributed unit node that multiple traffic flows in the uplink direction for the user equipment are to be merged into a single traffic flow, and wherein the information comprises at least one of the following information for a traffic flow in the uplink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The apparatus of claim 50, wherein:

the integrated access and backhaul network node is an integrated access and backhaul node;

the information that traffic flow in a downlink direction for the user equipment is to be duplicated comprises at least one of the following for a traffic flow in the downlink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header; and

the information that traffic flow in an uplink direction for the user equipment is to be merged comprises at least one of the following for a traffic flow in the uplink direction:

a backhaul radio link control channel identity;

a routing identification;

a tunnel endpoint identifier; or

any field of a backhaul adaptation protocol header.
The apparatus of any one of claims 29 to 53 wherein the means comprises:

at least one processor; and

at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.
An apparatus, comprising:

one or more processors; and

one or more memories including computer program code,

wherein the one or more memories and the computer program code are configured, with the one or more processors, to cause the apparatus to perform operations comprising:

in an integrated access and backhaul network node that is part of a radio access network in communication with a user equipment, performing the following:

receiving configuration with information indicating which data is to be duplicated in a downlink direction and to be merged in an uplink direction;

in the downlink direction, receiving first data over a backhaul link for a single data radio bearer associated with the user equipment, determining the first data is indicated as data to be duplicated, duplicating the first data into multiple downlink traffic flows, and transmitting the multiple downlink traffic flows toward the user equipment; and

in the uplink direction, receiving second data over multiple uplink traffic flows from the user equipment, determining the second data is indicated as data to be merged, merging the second data into a single traffic flow, and forwarding the single traffic flow toward the network over the backhaul link.
An apparatus, comprising:

one or more processors; and

one or more memories including computer program code,

wherein the one or more memories and the computer program code are configured, with the one or more processors, to cause the apparatus to perform operations comprising:

receiving data for a user equipment at an integrated access and backhaul donor distributed unit node;

determining by the integrated access and backhaul donor distributed unit node the data is associated with a data radio bearer that is to be duplicated;

adding by the integrated access and backhaul donor distributed unit node a duplication indication associated with the data; and

forwarding, by the integrated access and backhaul donor distributed unit node, the data with the added duplication indication toward an integrated access and backhaul node that is to perform the duplication of the data.
An apparatus, comprising:

one or more processors; and

one or more memories including computer program code,

wherein the one or more memories and the computer program code are configured, with the one or more processors, to cause the apparatus to perform operations comprising:

at an integrated access and backhaul donor control unit in a network, performing the following:

determining traffic flow for a user equipment is to be duplicated by an integrated access and backhaul network node in the network; and

configuring an integrated access and backhaul network node with at least one of information that traffic flow in a downlink direction for the user equipment is to be duplicated, and information that traffic flow in an uplink direction for the user equipment is to be merged.