WO2022083865A1 - Procédé, appareil et programme d'ordinateur - Google Patents

Procédé, appareil et programme d'ordinateur Download PDF

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Publication number
WO2022083865A1
WO2022083865A1 PCT/EP2020/079723 EP2020079723W WO2022083865A1 WO 2022083865 A1 WO2022083865 A1 WO 2022083865A1 EP 2020079723 W EP2020079723 W EP 2020079723W WO 2022083865 A1 WO2022083865 A1 WO 2022083865A1
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WO
WIPO (PCT)
Prior art keywords
packet
node
discard timer
routing
network node
Prior art date
Application number
PCT/EP2020/079723
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English (en)
Inventor
Osman Nuri Can Yilmaz
Henri Markus Koskinen
Matti Einari Laitila
Original Assignee
Nokia Technologies Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nokia Technologies Oy filed Critical Nokia Technologies Oy
Priority to PCT/EP2020/079723 priority Critical patent/WO2022083865A1/fr
Publication of WO2022083865A1 publication Critical patent/WO2022083865A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/22—Alternate routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/28—Routing or path finding of packets in data switching networks using route fault recovery

Definitions

  • the present application relates to a method, apparatus, and computer program for a wireless communication system.
  • a communication system be a facility that enables communication sessions between two or more entities such as user terminals, base stations/access points and/or other nodes by providing carriers between the various entities involved in the communications path.
  • a communication system can be provided, for example, by means of a communication network and one or more compatible communication devices.
  • the communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on.
  • Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.
  • an apparatus comprising means configured to perform: routing at least one packet to a network node on a backhaul link using a primary path; storing the at least one packet; starting a discard timer, the discard timer representing a duration of time that the at least one packet will be stored; and in response to receiving a failure message before the discard timer expires, rerouting the stored at least one packet to a further network node using an alternative path.
  • the at least one packet may be routed to the network node via a first backhaul radio link control channel, and the at least one packet is re-routed to the further network node via a second backhaul radio link control channel.
  • the means may be further configured to perform: in response to receiving an acknowledgement message on the first backhaul radio link control channel from the network node before the discard timer expires, continuing to store the at least one packet.
  • the failure message may indicate at least one of: congestion on the primary path, a radio link failure on the primary path, a backhaul radio link failure recovery failure, and a backhaul failure on the primary path.
  • There may be a trigger for starting the discard timer which may be one of: upon receival of the at least one packet at the apparatus, upon routing of the at least one packet to the network node, upon receiving an indication that the whole at least one packet has been transmitted, and upon receival of an acknowledgement message from the network node that the at least one packet has been received.
  • the means may be further configured to perform: in response to receiving the failure message, continuing to re-route the at least one packet using the alternative path until a reachable message is received, wherein the reachable message indicates that the primary path can be used.
  • the means may be further configured to perform: in response to receiving the failure message, starting an alternative path timer; re-routing data to the further network node using the alternative path; and in response to the alternative path timer expiring, routing data to the network node using the primary path.
  • the means may be further configured to perform: determining the duration of time of the discard timer based on a number of nodes in the primary path between the apparatus and a destination node of the primary path.
  • the means may be further configured to perform: receiving the duration of time of the discard timer from a donor node.
  • the means may be further configured to perform: determining the duration of time of the discard timer based on a quality of service requirement of the primary path.
  • the means may be further configured to perform: collecting performance data over time; and using the collected performance data to adjust the duration of time for the discard timer.
  • the re-routing may performed at an intermediate node of at least one of: the primary path, and the alternative path.
  • the means may be further configured to perform: receiving an indication from a donor node that local re-routing at the intermediate node is allowed and which channels are available for re-routing.
  • the at least one packet may comprise a backhaul adaptation protocol protocol data unit.
  • the apparatus may be comprised within an integrated access and backhaul node.
  • a method comprising: routing at least one packet to a network node on a backhaul link using a primary path; storing the at least one packet; starting a discard timer, the discard timer representing a duration of time that the at least one packet will be stored; and in response to receiving a failure message before the discard timer expires, re-routing the stored at least one packet to a further network node using an alternative path.
  • the at least one packet may be routed to the network node via a first backhaul radio link control channel, and the at least one packet is re-routed to the further network node via a second backhaul radio link control channel.
  • the method may comprise: in response to receiving an acknowledgement message on the first backhaul radio link control channel from the network node before the discard timer expires, continuing to store the at least one packet.
  • the failure message may indicate at least one of: congestion on the primary path, a radio link failure on the primary path, a backhaul radio link failure recovery failure, and a backhaul failure on the primary path.
  • There may be a trigger for starting the discard timer which may be one of: upon receival of the at least one packet at the apparatus, upon routing of the at least one packet to the network node, upon receiving an indication that the whole at least one packet has been transmitted, and upon receival of an acknowledgement message from the network node that the at least one packet has been received.
  • the method may comprise: in response to receiving the failure message, continuing to re-route the at least one packet using the alternative path until a reachable message is received, wherein the reachable message indicates that the primary path can be used.
  • the method may comprise: in response to receiving the failure message, starting an alternative path timer; re-routing data to the further network node using the alternative path; and in response to the alternative path timer expiring, routing data to the network node using the primary path.
  • the method may comprise: determining the duration of time of the discard timer based on a number of nodes in the primary path between the apparatus and a destination node of the primary path.
  • the method may comprise: receiving the duration of time of the discard timer from a donor node.
  • the method may comprise: determining the duration of time of the discard timer based on a quality of service requirement of the primary path.
  • the method may comprise: collecting performance data over time; and using the collected performance data to adjust the duration of time for the discard timer.
  • the re-routing may performed at an intermediate node of at least one of: the primary path, and the alternative path.
  • the method may comprise: receiving an indication from a donor node that local re-routing at the intermediate node is allowed and which channels are available for rerouting.
  • the at least one packet may comprise a backhaul adaptation protocol protocol data unit.
  • the method may be performed by an integrated access and backhaul node.
  • an apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: routing at least one packet to a network node on a backhaul link using a primary path; storing the at least one packet; starting a discard timer, the discard timer representing a duration of time that the at least one packet will be stored; and in response to receiving a failure message before the discard timer expires, re-routing the stored at least one packet to a further network node using an alternative path.
  • the at least one packet may be routed to the network node via a first backhaul radio link control channel, and the at least one packet is re-routed to the further network node via a second backhaul radio link control channel.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving an acknowledgement message on the first backhaul radio link control channel from the network node before the discard timer expires, continuing to store the at least one packet.
  • the failure message may indicate at least one of: congestion on the primary path, a radio link failure on the primary path, a backhaul radio link failure recovery failure, and a backhaul failure on the primary path.
  • There may be a trigger for starting the discard timer which may be one of: upon receival of the at least one packet at the apparatus, upon routing of the at least one packet to the network node, upon receiving an indication that the whole at least one packet has been transmitted, and upon receival of an acknowledgement message from the network node that the at least one packet has been received.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving the failure message, continuing to re-route the at least one packet using the alternative path until a reachable message is received, wherein the reachable message indicates that the primary path can be used.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: in response to receiving the failure message, starting an alternative path timer; re-routing data to the further network node using the alternative path; and in response to the alternative path timer expiring, routing data to the network node using the primary path.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: determining the duration of time of the discard timer based on a number of nodes in the primary path between the apparatus and a destination node of the primary path.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: receiving the duration of time of the discard timer from a donor node.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: determining the duration of time of the discard timer based on a quality of service requirement of the primary path.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: collecting performance data over time; and using the collected performance data to adjust the duration of time for the discard timer.
  • the re-routing may performed at an intermediate node of at least one of: the primary path, and the alternative path.
  • the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform: receiving an indication from a donor node that local re-routing at the intermediate node is allowed and which channels are available for re-routing.
  • the at least one packet may comprise a backhaul adaptation protocol protocol data unit.
  • the apparatus may be comprised within an integrated access and backhaul node.
  • a computer program comprising computer executable instructions which when run on one or more processors perform: routing at least one packet to a network node on a backhaul link using a primary path; storing the at least one packet; starting a discard timer, the discard timer representing a duration of time that the at least one packet will be stored; and in response to receiving a failure message before the discard timer expires, re-routing the stored at least one packet to a further network node using an alternative path.
  • a computer product stored on a medium may cause an apparatus to perform the methods as described herein.
  • An electronic device may comprise apparatus as described herein.
  • ALISF Authentication Server Function
  • AMF Access Management Function
  • CU Centralised Unit DN: Data Network
  • DU Distributed Unit eNB: eNodeB
  • gNB gNodeB
  • IAB Integrated Access and Backhaul
  • NEF Network Exposure Function
  • NRF Network Repository Function
  • PDCP Packet Data Convergence Protocol
  • UE User Equipment
  • 5GC 5G Core network
  • 5G-AN 5G Radio Access Network
  • Figure 1 shows a schematic representation of a 5G system
  • Figure 2 shows a schematic representation of a control apparatus
  • Figure 3 shows a schematic representation of a terminal
  • Figure 4 shows a schematic representation of integrated access and backhaul architecture
  • Figure 5 shows a schematic representation of a multi-hop integrated access and backhaul deployment
  • Figure 6 shows another schematic representation of a multi-hop integrated access and backhaul deployment
  • Figure 7 shows an example method flow diagram performed by a network entity
  • Figure 8 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the method of Figure 7.
  • mobile communication devices/terminals or user apparatuses, and/or user equipments (UE), and/or machine-type communication devices 102 are provided wireless access via at least one base station (not shown) or similar wireless transmitting and/or receiving node or point.
  • a communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other devices.
  • the communication device may access a carrier provided by a station or access point, and transmit and/or receive communications on the carrier.
  • FIG. 1 shows a schematic representation of a 5G system (5GS) 100.
  • the 5GS may comprises a terminal 102, a 5G access network (5G-AN) 106, a 5G core network (5GC) 104, one or more network functions (NF), one or more application function (AF) 108 and one or more data networks (DN) 110.
  • 5G-AN 5G access network
  • 5GC 5G core network
  • NF network functions
  • AF application function
  • DN data networks
  • the 5G-AN 106 may comprise one or more gNodeB (gNB) distributed unit functions connected to one or more gNodeB (gNB) centralized unit functions.
  • gNB gNodeB
  • gNB gNodeB
  • the 5GC 104 may comprise an access management function (AMF) 112, a session management function (SMF) 114, an authentication server function (ALISF) 116, a user data management (UDM) 118, a user plane function (UPF) 120, a network exposure function (NEF) 122 and/or other NFs.
  • AMF access management function
  • SMF session management function
  • ALISF authentication server function
  • UDM user data management
  • UPF user plane function
  • NEF network exposure function
  • mobile communication devices/terminals or user apparatuses, and/or user equipments (UE), and/or machine-type communication devices are provided with wireless access via at least one base station or similar wireless transmitting and/or receiving node or point.
  • the terminal is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other devices.
  • the communication device may access a carrier provided by a station or access point, and transmit and/or receive communications on the carrier.
  • FIG 2 illustrates an example of a control apparatus 200 for controlling a function of the 5G-AN or the 5GC as illustrated on Figure 1 .
  • the control apparatus may comprise at least one random access memory (RAM) 211 a, at least on read only memory (ROM) 211 b, at least one processor 212, 213 and an input/output interface 214.
  • the at least one processor 212, 213 may be coupled to the RAM 211 a and the ROM 211 b.
  • the at least one processor 212, 213 may be configured to execute an appropriate software code 215.
  • the software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects.
  • the software code 215 may be stored in the ROM 211 b.
  • the control apparatus 200 may be interconnected with another control apparatus 200 controlling another function of the 5G-AN or the 5GC.
  • each function of the 5G-AN or the 5GC comprises a control apparatus 200.
  • two or more functions of the 5G-AN or the 5GC may share a control apparatus.
  • FIG 3 illustrates an example of a terminal 300, such as the terminal illustrated on Figure 1 .
  • the terminal 300 may be provided by any device capable of sending and receiving radio signals.
  • Non-limiting examples comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CloT) device or any combinations of these or the like.
  • the terminal 300 may provide, for example, communication of data for carrying communications.
  • the communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.
  • the terminal 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals.
  • transceiver apparatus is designated schematically by block 306.
  • the transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement.
  • the antenna arrangement may be arranged internally or externally to the mobile device.
  • the terminal 300 may be provided with at least one processor 301 , at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices.
  • the at least one processor 301 is coupled to the RAM 302a and the ROM 211 b.
  • the at least one processor 301 may be configured to execute an appropriate software code 308.
  • the software code 308 may for example allow to perform one or more of the present aspects.
  • the software code 308 may be stored in the ROM 302b.
  • the processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304.
  • the device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like.
  • a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like.
  • one or more of a display, a speaker and a microphone may be provided depending on the type of the device.
  • IAB integrated access & backhaul
  • a network operator can utilise part of the radio resources (access resources) for wireless backhauling.
  • One of the purposes of IAB is to improve on existing backhaul systems with a more flexible wireless backhaul using existing 3GPP bands providing not only backhaul but also existing cellular services in the same node.
  • IAB is currently considered as a work item in 3GPP.
  • 3GPP Rel-16 specifications include the new radio (NR) relaying option named as Integrated Access and Backhaul (IAB).
  • the adopted solution is a level 2 (L2) relay supporting multi-hop (multiple backhaul links) topologies.
  • the lAB-donor 401 comprises a centralised unit (CU) 403, and a distributed unit (DU) 405.
  • the lAB-donor 401 has an interface with a core network.
  • the core network is the 5G core network (5GC) 407 (also called the new radio core network (NGC)) which is labelled NG.
  • the core network is an evolved packet core (EPC).
  • the lAB-donor 401 has an interface labelled F1 with a first DU 411 comprised within a first lAB-node 409.
  • the lAB- donor has another interface labelled F1 with a second DU 415 comprised within a second lAB-node 413.
  • the first lAB-node 409 comprises a first mobile termination block (MT) 417.
  • the second lAB-node 413 comprises a second MT block 419.
  • the DU 405 of the lAB-donor 401 has a backhaul link with the first MT 417.
  • the first DU 411 of the first lAB-node 409 has a backhaul link with the second MT 419.
  • the lAB-donor 401 has an interface with a first user equipment (UE) 421 .
  • UE user equipment
  • the first lAB-node 409 has an interface with a second UE 423.
  • the second lAB-node has an interface with a third UE 425.
  • the lAB-donor, the first lAB-node 409 and the second lAB-node 413 may each be comprised within a base station (gNB).
  • two or more of the lAB-donor, the first lAB-node 409 and the second lAB-node 413 may be comprised within a single base station (gNB).
  • the core network interfaces are terminated at the lAB-donor 401.
  • the relaying between nodes is a radio access network (RAN) functionality. Relaying refers to forwarding data packets over the air.
  • the relaying uses RAN functionality because the core network (CN) is not involved.
  • the F1 interfaces between a DU 405, 411 , 415 and the CU 403 are carried over backhaul (BH) radio link control (RLC) channels.
  • BH backhaul
  • RLC radio link control
  • an lAB-node hosts the MT function corresponding to UE operation or a part of the UE operation.
  • the parent node could be an IAB node 409, 413 or the lAB-donor 401 .
  • the second lAB-node 413 is assigned one or more internet protocol (IP) addresses that is anchored in the IAB- donor DU 405. For example, an outer IP address when an IP security (IPSec) tunnel is enabled.
  • IP internet protocol
  • the lAB-donor DU 405 maps the DL F1-C/U packet to the related BH RLC channel based on the configuration that is previously configured by the lAB-donor CU 403.
  • the lAB-donor DU 405 may also map the DL F1 -C/U packet based on a differentiated services code point (DSCP)Zflow label/IP address of the DL F1 -C/U packet.
  • DSCP differentiated services code point
  • the lAB-donor CU 403 uses specific DSCP/flow label in order to support the traffic mapping in the lAB-donor DU 405.
  • the NR BAP (Backhaul Adaptation Protocol) layer is responsible for routing in an IAB network 400 between the IAB node 409, 413 and the lAB-donor DU 405. Routing of packets may be based on a routing identification (ID) of the BAP layer header.
  • a routing ID comprises a BAP destination address and a path ID.
  • the BAP destination address identifies the destination node of the packet.
  • the path ID identifies the selected path.
  • Figure 5 shows a schematic representation of an IAB system 500 with two alternative paths.
  • Figure 5 shows a first lAB-node (IAB1 ) 501.
  • IAB1 501 comprises a first DU 503 and a first MT 505.
  • IAB2 507 comprises a second DU 509 and a second MT 511 .
  • IAB3 513 comprises a third DU 515 and a third MT 517.
  • An lAB- donor (Donorl ) 519 has interfaces with IAB2 and IAB3.
  • Donorl 519 comprises a fourth DU 521 and a fifth DU 523.
  • Donorl 519 also comprises a CU 525.
  • IAB1 501 is configured with two paths to the same destination (the fourth DU 521 of Donorl 519).
  • a first path (pathl ) 527 is from IAB1 to Donorl 519 via IAB2 507.
  • a second path (path2) 529 is from IAB1 to Donorl 519 via IAB3 513. Re-routing from path 1 527 to path 2 529 can be decided locally at the IAB node if there is an alternative route to the same destination node. If pathl 527 is not available, IAB1 501 may select path2 529 for backhaul data destined for the fourth DU
  • a node that is configured with an alternative path for a packet does not discard the packet until a discard timer for that packet expires.
  • the node will not discard the packet even if one or more possible ACKs have been received by the node.
  • the packet can be held in a buffer at the node until the expiry of the discard timer.
  • the packet will be held in the buffer despite any ACKs received. If a message is received by the node that indicates the destination of the packet is unreachable before the discard timer expires, the buffered packet is re-transmitted via another node using a pre-configured alternative path. This will be described in more detail below.
  • the message there is a message received indicating that the destination is unreachable.
  • the message is sent by an IAB node detecting a failure of a link.
  • the message may indicate the reason for the unreachability, any affected destinations (destination BAP addresses), the routing IDs.
  • the message can cover both radio-link failure (RLF) and other failure cases.
  • Reasons for the failure may include, for example, node congestion, and node failures due to other reasons than the radio link problem. In other examples, there may be failure due to any other suitable reason.
  • the packet can be re-routed by a parent node (in case of downstream) or a child node (in case of upstream) without transferring the packet back to the parent (e.g., in case of downstream) or the child (e.g., in case of upstream), respectively.
  • This is done by discarding the buffered packet if no RLF/congestion report is received at the node for a certain period of time.
  • the timer that the node uses to determine how long to hold the data in the buffer is referred to as a discard timer.
  • Figure 6 shows another schematic representation of an IAB system 600 with two alternative paths.
  • Figure 6 shows a first lAB-node (IAB1 ) 601 .
  • IAB1 601 comprises a first DU 603 and a first MT 605.
  • IAB2 607 comprises a second DU 609 and a second MT 611 .
  • IAB3 613 comprises a third DU 615 and a third MT 617.
  • IAB4 619 comprises a fourth DU 621 and a fourth MT 623.
  • An lAB-donor (Donorl ) 625 has an interface with IAB3.
  • Donorl 625 comprises a sixth DU 627 and a seventh DU 629.
  • Donorl 625 also comprises a CU 631.
  • Donor 1 625 is configured with two paths to the same destination (the IAB1 601 ).
  • a first path (primary path) 633 is from Donorl 625 to IAB3 613, to IAB2 607, to the destination of IAB1 601 .
  • a second path (alternative path) 535 is from Donorl 625 to IAB3 613, to IAB2 607, to the destination of IAB1 601.
  • IAB3 613 is also configured with the primary path 633 and the alternative path 635.
  • the direction of the primary path 633 and the alternative path 635 in Figure 6 shows a downstream flow. It should be understood that these paths could operate in the opposite direction for an upstream flow.
  • IAB1 601 there may be a radio link failure or congestion which happens between IAB1 601 and IAB2 607 in the primary path.
  • a packet would need to be routed back from IAB2 607 to IAB3 613. Then the packet would travel along the alternative path 635, to IAB4 619 and finally to the destination of IAB1 601 .
  • IAB3 613 receives a packet from the Donorl 625. IAB3 transmits/routes the packet to IAB2 607 using the primary path 633. IAB3 613 may route the packet to IAB2 607 on an RLC channel. IAB3 stores the packet in a memory buffer (not shown in Figure 6). The memory buffer may be local to IAB3 613. In other examples, the memory buffer may be in a remote location, accessible by IAB3 613. IAB3 will then start a discard timer. The discard timer representing a duration of time that the packet will be stored. In an example, the discard timer is be started upon receival of the packet at IAB3 613.
  • the discard timer may be started when the packet is received at a specific protocol layer of IAB3 613. In another example, the discard timer is started upon routing of the packet to IAB2607. In another example, the discard timer is started upon receiving an indication that the whole packet has been transmitted/routed. In another example, the discard timer is started upon receival of an acknowledgement message from IAB2 607 that the packet has been received. IAB3 613 may receive a failure message before the discard timer expires. The failure message may be, for example, a backhaul RLF message. If IAB3 613 receives a failure message before the discard timer expires, then IAB3 613 collects the packet from the memory buffer.
  • IAB3 613 then re-routes the packet to IAB4 619 using the alternate path 635.
  • IAB4 619 can then route the data packet to IAB1 601.
  • IAB1 601 is the original destination for the packet, before the failure occurred.
  • the packet may comprise a BAP protocol data unit (PDU).
  • PDU BAP protocol data unit
  • the IAB3 613 does not discard the buffered packet for a time period set by a discard timer. While the discard timer is running, the node may expect to receive an RLF report or an unreachable message. If an RLF report or unreachable message is received, then IAB3 613 can directly re-route the buffered packet to IAB4 619 using the alternative path 635. This means that the packet does not need to be re-routed back from IAB2 607 to IAB3 613 as the packet is already stored in the memory buffer of IAB3 613. This may save radio resources. It should be understood that the nodes referenced in the example above, are given as an example for understanding only. In other examples, failures or congestion may occur between other nodes in the system.
  • the primary path 633 along with the discard timer will be used in upstream or downstream even if an unreachable message or RLF report has been previously received for the primary path 633.
  • the parent node in the downstream, stores a packet that it receives in a buffer.
  • the parent node will not discard the downstream packet until a discard timer expires. Once the discard timer expires, the parent node will discard the packet from the buffer.
  • the time duration of the discard timer may be pre-determined. In other examples, the time duration of the discard timer may be signalled to the node. The packet can be held in the buffer until the expiry of the timer even if an acknowledgement message is received at the parent node.
  • the buffered packet is re-routed via a child node using an alternative path/route. It should be understood that this example is also applicable in the upstream. In the upstream a child node does not discard the upstream packet until a discard timer expires.
  • the pre-configured alternative route is continued to be used until a ‘reachable’ message is received. The “reachable” message indicating that the previous failure or congestion is no longer present.
  • the pre-configured alternative route is continued to be used until a further timer expires. The further timer specifies how long the alternative path can be used for.
  • re-routing can be performed at an intermediate IAB node in the path.
  • Re-routing can be controlled by the IAB donor CU. In this case, it can be indicated whether the intermediate IAB node can perform local re-routing. It can also be indicated which RLC channels can be re-routed at the intermediate node.
  • re-routing can be done at an intermediate IAB node in the path.
  • a destination node may remain the same when there is a radio link failure or there is congestions. This is because the intermediate IAB node cannot change a BAP routing ID or a source IP address. In this situation, the access IAB node could change the BAP routing ID or the source IP address.
  • the intermediate node in the path can change the destination node.
  • the intermediate node may be able to change routing parameters.
  • the routing parameters may include, for example, the BAP routing ID. By changing the BAP routing ID, the destination node can be changed.
  • re-routing in the upstream, can be controlled by an IAB donor CU.
  • the IAB donor CU may send a message to the IAB node indicating that the IAB node can perform local re-routing.
  • the same message may also include information about which value to use for a discard timer.
  • the IAB donor CU may also indicate which RLC channels can be rerouted at the intermediate node.
  • the IAB donor CU sends a link failure indication to the IAB node.
  • the IAB donor CU sends a re-routing command to the IAB node.
  • timer values there are different timer values configured per RLC channel. Packets will be mapped to lower layers, such as the RLC channel. There may be RLC channel mapping before the discard timer starts. If the discard timer is RLC channel specific then different timers per channel can be used. The timer values may be dependent on the number of hops remaining in the configured route. In other examples the timer values may be dependent on a quality of service (QoS)Zlatency requirement of the channel. In some examples, mapping a packet to a specific RLC channel used for transmitting the packet is performed before the timer is started for the packet.
  • QoS quality of service
  • a discard timer at an IAB node is started upon receival of a packet at BAP layer. In some examples, the discard timer is started upon BAP submitting a BAP PDU to a lower layer. In other examples, a discard timer is started upon the transmission of a packet from an IAB node. For example, the discard timer is started upon receiving an indication from an (egress) RLC channel that the whole BAP PDU has been transmitted. In other examples, a discard timer is started at an IAB node upon receival of an RLC acknowledgement message for a given packet being transmitted. The acknowledgement message may be received at the IAB node from another IAB node.
  • a duration of the discard timer is a pre-determined value.
  • the discard timer value can be optimised/altered depending on collected performance data over time.
  • the entire data buffer is subject to the discard timer.
  • part of the data buffer is subject to the discard timer.
  • the packets to be temporarily buffered (during the discard timer) is left to the implementation.
  • the packets to be buffered can be optimised depending on collected performance data over time.
  • the examples described above are also applicable to mobile IAB scenarios.
  • the IAB topology tends to change more often and faster.
  • the latency and resource efficiency requirements become more important. For example, re-routing packets back to the parent/child in case of an RLF may not possible.
  • the re-routing of packets may not be possible because not only are the hop toward/from descendant node affected by the mobility, but also the other hops can be affected by the mobility.
  • the hops may also be affected by the associated changes in radio environment.
  • the RLC (channel) referred to in the example above can be replaced by a backhaul RLC (channel)). Furthermore, the RLF referred to in the examples above can be replaced by a backhaul RLF.
  • One or more of the examples discussed above mean that data loss can be avoided. Furthermore, local re-routing can be performed without causing further congestion in the reverse stream direction. This can be due to the fact that the data does not need to be re-routed from a child node to a parent node, and then the parent node to another child node. This is in the case of the downstream traffic but is applicable as vice versa in the upstream. Furthermore, jitter is also reduced since back and forth routing for part of the traffic is avoided.
  • One or more of the examples allows for more efficient use of backhaul radio resources and less interference thereof. Furthermore, the need for radio resource management and coordination/overhead is reduced.
  • the solutions described above are applicable for both downstream and upstream. Lastly, one or more examples can also improve mobile IAB performance.
  • Figure 7 shows an example method flow performed by an apparatus.
  • the apparatus may be comprised within a network node.
  • the network node may be, for example, an IAB node.
  • the IAB node may be comprised within a base station (gNB).
  • gNB base station
  • the method comprises routing at least one packet to a network node on a backhaul link using a primary path.
  • the method comprises storing the at least one packet.
  • the method comprises starting a discard timer, the discard timer representing a duration of time that the at least one packet will be stored.
  • the method comprises, in response to receiving a failure message before the discard timer expires, re-routing the stored at least one packet to a further network node using an alternative path.
  • Figure 8 shows a schematic representation of non-volatile memory media 800a (e.g. computer disc (CD) or digital versatile disc (DVD)) and 800b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 802 which when executed by a processor allow the processor to perform one or more of the steps of the method of Figure 7.
  • 800a e.g. computer disc (CD) or digital versatile disc (DVD)
  • 800b e.g. universal serial bus (USB) memory stick
  • some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.
  • some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto.
  • firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
  • the examples may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions.
  • the software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.
  • the memory 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, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.
  • the data processors 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), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples.
  • circuitry may be configured to perform one or more of the functions and/or method steps previously described. That circuitry may be provided in the base station and/or in the communications device.
  • circuitry may refer to one or more or all of the following:
  • 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.
  • software e.g., firmware
  • 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.
  • circuitry also covers, for example integrated device.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un appareil comprenant un moyen configuré pour effectuer un acheminement (S701) d'au moins un paquet à un noeud de réseau sur une liaison de backhaul via un trajet primaire, et stocker (S703) le ou les paquets. Le moyen est également configuré pour effectuer un démarrage (S705) d'un temporisateur de rejet, le temporisateur de rejet représentant une durée pendant laquelle le ou les paquets seront stockés. En réponse à la réception d'un message d'échec avant l'expiration du temporisateur de rejet, le moyen est configuré pour effectuer un réacheminement (S707) du ou des paquets stockés à un autre noeud de réseau via un trajet alternatif.
PCT/EP2020/079723 2020-10-22 2020-10-22 Procédé, appareil et programme d'ordinateur WO2022083865A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019245443A2 (fr) * 2018-06-21 2019-12-26 Telefonaktiebolaget Lm Ericsson (Publ) Prévention/atténuation de perte de paquets dans des systèmes iab
WO2020085969A1 (fr) * 2018-10-24 2020-04-30 Telefonaktiebolaget Lm Ericsson (Publ) Procédés de gestion de défaillances de liaison dans des réseaux de liaison terrestre à accès intégré (iab)

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019245443A2 (fr) * 2018-06-21 2019-12-26 Telefonaktiebolaget Lm Ericsson (Publ) Prévention/atténuation de perte de paquets dans des systèmes iab
WO2020085969A1 (fr) * 2018-10-24 2020-04-30 Telefonaktiebolaget Lm Ericsson (Publ) Procédés de gestion de défaillances de liaison dans des réseaux de liaison terrestre à accès intégré (iab)

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