WO2021215979A1 - Procédés et nœuds dans des réseaux de liaison terrestre à accès intégré - Google Patents

Procédés et nœuds dans des réseaux de liaison terrestre à accès intégré Download PDF

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WO2021215979A1
WO2021215979A1 PCT/SE2021/050314 SE2021050314W WO2021215979A1 WO 2021215979 A1 WO2021215979 A1 WO 2021215979A1 SE 2021050314 W SE2021050314 W SE 2021050314W WO 2021215979 A1 WO2021215979 A1 WO 2021215979A1
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message
node
network node
iab
network
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PCT/SE2021/050314
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Oumer TEYAB
Icaro L. J. Da Silva
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Telefonaktiebolaget Lm Ericsson (Publ)
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/02—Access restriction performed under specific conditions
    • H04W48/06—Access restriction performed under specific conditions based on traffic conditions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/16—Performing reselection for specific purposes
    • H04W36/22—Performing reselection for specific purposes for handling the traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04—Large scale networks; Deep hierarchical networks
    • H04W84/042—Public Land Mobile systems, e.g. cellular systems
    • H04W84/047—Public Land Mobile systems, e.g. cellular systems using dedicated repeater stations

Definitions

  • the present disclosure generally relates to the field of wireless network communications, and more particularly to techniques supporting handling of releases and connection reconfigurations in integrated access backhaul (IAB) networks.
  • IAB integrated access backhaul
  • Densification via the deployment of more and more base stations is one of the mechanisms that can be employed to satisfy the ever-increasing demand for more and more bandwidth/capacity in mobile networks. Due to the availability of more spectrum in the millimeter-wave band, deploying small cells that operate in this band is an attractive deployment option for these purposes. However, deploying fiber to small cells, which is the usual way in which small cells are deployed, can end up being very expensive and impractical. Thus, employing a wireless link for connecting small cells to an operator’s network is a cheaper and practical alternative.
  • IAB integrated access backhaul
  • Integrated access and backhaul has been studied earlier by members of the Third- Generation Partnership Project (3GPP) in the scope of Long-Term Evolution (LTE) Rel-10.
  • 3GPP Third- Generation Partnership Project
  • a relay node has the functionality of both an LTE eNB and a user equipment (UE) modem.
  • the RN is connected to a donor eNB that has a S1/X2 proxy functionality hiding the RN from the rest of the network.
  • This architecture enables the donor eNB to also be aware of the UEs behind the RN and hide, from the core network (CN), any UE mobility between the donor eNB and RN.
  • CN core network
  • IAB is again an advantageous solution.
  • the main IAB principle is the use of wireless links for the backhaul (instead of fiber) to enable flexible and very dense deployment of cells without the need for densifying the transport network.
  • Use case scenarios for IAB can include coverage extension, deployment of massive number of small cells and fixed wireless access (FWA), e.g., to residential/office buildings.
  • FWA fixed wireless access
  • the larger bandwidth available for NR in mm-wave spectrum provides opportunity for self-backhauling, without limiting the spectrum to be used for the access links.
  • MIMO multiple-input multiple- output
  • the specifications for IAB strive to reuse existing functions and interfaces already defined in NR.
  • the designs for the MT, gNB-DU, gNB-CU, UPF, AMF and SMF functions, as well as those for the corresponding interfaces NRUu (between MT and gNB), FI, NG, X2 and N4 are used as a baseline for the IAB architectures. Modifications or enhancements to these functions and interfaces for the support of IAB will be explained as necessary in the context of the architecture discussion. Additional functionality such as multi-hop forwarding is included in the architecture discussion as it is necessary for the understanding of IAB operation and since certain aspects may require standardization.
  • the Mobile-Termination (MT) function has been defined as a component of the IAB node.
  • MT is referred to as a function residing on an IAB-node that terminates the radio interface layers of the backhaul Uu interface toward the IAB-donor or other IAB-nodes.
  • Figure 1 illustrates a high-level view of the 5G network architecture, consisting of a Next Generation RAN (NG-RAN) and a 5G Core (5GC).
  • the NG-RAN can comprise a set of gNodeBs (gNBs) connected to the 5GC via one or more NG interfaces, whereas the gNBs can be connected to each other via one or more Xn interfaces.
  • gNBs gNodeBs
  • Each of the gNBs can support frequency- division duplexing (FDD), time-division duplexing (TDD), or a combination thereof.
  • FDD frequency- division duplexing
  • TDD time-division duplexing
  • the NGRAN logical nodes shown in Figure 1 include a Central Unit (CU or gNB-CU) and one or more Distributed Units (DU or gNB-DU).
  • a CU is a logical node that is a centralized unit that hosts high layer protocols and includes a number of gNB functions, including controlling the operation of DUs.
  • a DU is a decentralized logical node that hosts lower layer protocols and can include, depending on the functional split option, various subsets of the gNB functions. (As used herein, the terms “central unit” and “centralized unit” are used interchangeably, and the terms “distributed unit” and “decentralized unit” are used interchangeability.)
  • the NG, Xn-C, and FI interfaces shown in Figure 1 are logical interfaces.
  • the NG and Xn-C interfaces for a split gNB terminate in the gNB-CU.
  • the Evolved UMTS Terrestrial Radio Access Network referred to as E- UTRAN-NR Dual Connectivity (EN-DC)
  • the Sl-U and X2-C interfaces for a split gNB terminate in the gNB-CU.
  • the gNB-CU connects to gNB-DUs over respective FI logical interfaces.
  • the gNB-CU and connected gNB-DUs are only visible to other gNBs and the 5GC as a gNB, e.g., the FI interface is not visible beyond gNB-CU.
  • a CU can host protocols such as RRC and PDCP, while a DU can host protocols such as RLC, MAC and PHY.
  • the CU is assumed to host RRC and PDCP, where PDCP is assumed to handle both UP traffic and CP traffic.
  • other exemplary embodiments may utilize other protocol splits that by hosting certain protocols in CU and certain others in the DU.
  • Exemplary embodiments can also locate centralized control plane protocols (e.g., PDCP-C and RRC) in a different CU with respect to the centralized user plane protocols (e.g., PDCP-U).
  • FIG. 2 shows a reference diagram for IAB in standalone mode, which contains one IAB donor and multiple IAB nodes.
  • the IAB donor is treated as a single logical node that comprises a set of functions such as gNB-DU, gNB-CU-CP, gNB-CU-UP, and potentially other functions.
  • the IAB-donor can be split according to these functions, which can all be either collocated or non-collocated as allowed by 3GPP NG-RAN architecture. IAB-related aspects may arise when such split is exercised. Also, some of the functions presently associated with the IAB-donor may eventually be moved outside of the donor if it becomes evident that they do not perform IAB-specific tasks.
  • the baseline user plane and control plane protocol stacks for IAB are shown in Figures 3 and 4, the latter of which is divided into Figure 4A, Figure 4B, and Figure 4C.
  • the chosen protocol stacks reuse the current CU-DU split specification in Rel-15, where the full user plane Fl-U (GTP-U/UDP/IP) is terminated at the IAB node (like a normal DU) and the full control plane Fl-C (Fl-AP/SCTP/IP) is also terminated at the IAB node (like a normal DU).
  • NDS Network Domain Security
  • IPsec IPsec in the case of UP, and DTLS in the case of CP
  • IPsec could also be used for the CP protection instead of DTLS (in this case no DTLS layer would be used).
  • Backhaul Adaptation Protocol A new protocol layer called Backhaul Adaptation Protocol (BAP) has been introduced in the IAB nodes and the IAB donor.
  • BAP is used for routing of packets to the appropriate downstream/upstream node and also mapping the UE bearer data to the proper backhaul RLC channel (and also between ingress and egress backhaul RLC channels in intermediate IAB nodes) to satisfy the end-to-end QoS requirements of bearers.
  • the UE establishes RLC channels to the DU on the UE's access IAB node in compliance with 3GPP TS 38.300. Each of these RLC-channels is extended via Fl-U between the UE's access DU and the IAB donor.
  • the information embedded in Fl-U is carried over backhaul RLC channels across the backhaul links. Transport of Fl-U over the wireless backhaul will be performed by the BAP. Since BAP is a newly defined layer for IAB networks, 3GPP has made only the following agreements related to the BAP layer functionality:
  • routing and bearer mapping (e.g., mapping of BH RLC channels) are BAP layer functions.
  • RAN2 assumes that the TX part of the BAP layer performs routing and “bearer mapping”, and the RX part of the BAP layer performs “bearer de-mapping”. RAN2 assumes that SDUs are forwarded from the RX part of the BAP layer to the TX part of the BAP layer (for the next hop) for packets that are relayed by the IAB node.
  • the BAP routing id (carried in the BAP header) consists of BAP address and BAP path ID.
  • Each BAP address defines a unique destination (unique for IAB network of one donor-IAB, either an IAB access node, or the IAB donor)
  • Each BAP address can have one or multiple entries in the routing table to enable local route selection. Multiple entries are for load balancing, re-routing at RLF.
  • Each BAP routing id has only one entry in the routing table.
  • the routing table can hold other information, e.g., priority level for entries with same BAP address, to support local selection. Configuration of this information is optional. - Load balancing by routing by donor-IAB CU shall be possible.
  • Identifiers may be required (e.g., if multiple BH RLC-channels are multiplexed into a single BH logical channel). Which exact identifiers are needed, and which of these identifier(s) are placed within the adaptation layer header depends on the architecture/protocol option.
  • Nodes A1 and A2 are IAB donor nodes; nodes B to H are IAB nodes;
  • the blue dashed line represents the established connection between two nodes; -
  • the red arrow represents the established route after BH-link failure, and the red dashed line represents the new established connection.
  • the backhaul-link failure occurs between on upstream IAB node (e.g., IAB node C) and one of its parent IAB nodes (e.g., IAB node B), where the upstream IAB node (IAB node C) has an additional link established to another parent node (IAB node E).
  • upstream IAB node e.g., IAB node C
  • parent IAB nodes e.g., IAB node B
  • the backhaul-link failure occurs between an upstream IAB node (e.g., IAB node C) and all its parent IAB nodes (e.g., IAB nodes B and E).
  • the upstream IAB node (IAB node C) has to reconnect to a new parent node (e.g., IAB node F), and the connection between IAB node F and IAB node C is newly established).
  • the backhaul-link failure occurs between IAB node C and IAB node D.
  • IAB node D has to reconnect to the new IAB donor (e.g., IAB donor A2) via a new route.
  • RAN2 assumes that there is an RFF-notifi cation at BH RFF, at least to downstream node(s).
  • Type 1 - “Plain” notification Indication that BH link RFF is detected by the IAB node.
  • Type 2 - “Trying to recover” Indication that BH link RLF is detected by the IAB node, and the IAB node is attempting to recover from it.
  • Type 3 “BH link recovered”: Indication that the BH link successfully recovers from RLF.
  • Type 4 “Recovery failure”: Indication that the BH link RLF recovery failure occurs.
  • the IAB node being configured with at least one RRC Reconfiguration message (e.g., including a reconfiguration with sync) for at least one target candidate, that is intended for a UE that is being served by the IAB node, as well as an indication that the message is conditional.
  • the IAB node receives the at least one RRC Reconfiguration message and stores it. Then, the IAB node starts monitoring a triggering condition (e.g., occurrence of RLF for the backhaul link between IAB node and its parent node). Upon the fulfillment of the triggering condition, the IAB node selects one of the RRC Reconfiguration messages and transmits it to the UE.
  • a triggering condition e.g., occurrence of RLF for the backhaul link between IAB node and its parent node.
  • the IAB node is configured with a conditional RRC Release message that is intended for a UE that is being served by the IAB node, as well as a trigger condition to send this RRC Release message.
  • the IAB node will store this RRC Release message and will transmit it to the UE only when the trigger condition is fulfilled, e.g., when the IAB node experiences BH RLF failure towards its parent node.
  • the IAB node is sent a conditional reconfiguration message (e.g., an RRC Reconfiguration message) to be forwarded to the UE, the conditional reconfiguration message comprising at least one RRC Reconfiguration message per target candidate (e.g., including a reconfiguration with sync), that is immediately provided to the UE that is being served by the IAB node.
  • a conditional reconfiguration message e.g., an RRC Reconfiguration message
  • the conditional reconfiguration message comprising at least one RRC Reconfiguration message per target candidate (e.g., including a reconfiguration with sync)
  • target candidate e.g., including a reconfiguration with sync
  • the UE receives the conditional reconfiguration message (including at least one RRC Reconfiguration per target candidate to be stored) and, upon detecting an RLF with the IAB node it performs cell selection while timer T311 is running, and, if the selected cell is one of the cells for which the UE has a stored RRC Reconfiguration message, the UE applies the message, i.e., it executes a conditional handover, otherwise it performs a re establishment.
  • the detection of RLF at the UE may be forced by the IAB node, e.g., by the IAB node stopping the transmission of radio link monitoring (RLM) reference signals.
  • RLM radio link monitoring
  • An example method described below is a method in a relay node serving a UE and relaying communications between the UE and a core network, via a donor network node.
  • This example method comprises receiving, from the donor network node, a message for conditional delivery to the UE, the message including or being associated with one or more triggering conditions.
  • the relay node determines that at least one of the triggering conditions is fulfilled and, responsive to this determination, forwards the message to the UE.
  • Another example is a method in a donor network node serving a UE via at least a first relay node relaying communications between the UE and the donor network node.
  • This example method comprises preparing a message for conditional delivery by the first relay node to the UE, the message including or being associated with one or more triggering conditions.
  • the method further comprises sending the message to the first relay node, the message including or being associated with an indication that the message is not to be delivered until at least one of the one or more triggering conditions is fulfilled.
  • Another example method described below is a method in a relay node serving a UE and relaying communications between the UE and a core network, via a donor network node.
  • This example method comprises receiving, from the donor network node, a first connection reconfiguration message for conditional delivery to the UE, the message including or being associated with one or more triggering conditions.
  • the method further comprises determining that at least one of the triggering conditions is fulfilled.
  • the method further comprises, responsive to this determination, forwarding the first connection reconfiguration message to the UE.
  • the message may be a RRC Reconfiguration message, for example.
  • the message may comprise redirection information directing the UE to select a cell at a given frequency.
  • Another example is a method in a donor network node serving a UE via at least a first relay node relaying communications between the UE and the donor network node.
  • This example method comprises preparing a connection reconfiguration message for conditional delivery by the first relay node to the UE, this message including or being associated with one or more triggering conditions.
  • the method further comprises sending the connection reconfiguration message to the first relay node, with the message including or being associated with an indication that the message is not to be delivered until at least one of the one or more triggering conditions is fulfilled.
  • the message may be an RRC Reconfiguration message.
  • the techniques and apparatuses described herein allow the network to let legacy UEs that are being served by an IAB node continue their connection with another network node (an IAB node or a standard base station), e.g., via a handover, when the IAB node experiences problems with the backhaul link towards its parent, without the UEs necessarily reverting to re establishment or NAS recovery via IDLE mode.
  • another network node an IAB node or a standard base station
  • Figure 1 illustrates an example of 5G logical network architecture.
  • Figure 2 shows a high-level architectural view of an Integrated Access & Backhaul (IAB) network.
  • IAB Integrated Access & Backhaul
  • Figure 3 shows the baseline User Plane (UP) protocol stack for IAB in Release 16 of the 3GPP standards.
  • Figure 4 A, Figure 4B, and Figure 4C illustrate the baseline control plane (CP) protocol stack for LAB in Release 16.
  • UP User Plane
  • CP control plane
  • Figure 5 shows an example of one-to-one mapping between UE dedicated radio bearer (DRB) and backhaul (BH) RLC Channel.
  • Figure 6 illustrates an example of many-to-one mapping between UE DRBs and BH RLC channels.
  • DRB dedicated radio bearer
  • BH backhaul
  • Figure 7, Figure 8, and Figure 9 each illustrate an example of a backhaul-link failure scenario.
  • Figure 10A shows a simplified signaling flow illustrating some of the embodiments disclosed herein.
  • Figure 10B shows a simplified signaling flow illustrating some others of the embodiments disclosed herein.
  • Figure 11 illustrates an example network node, according to some embodiments.
  • Figure 12 is a process flow diagram illustrating an example method as implemented in a relay node, according to some embodiments.
  • Figure 13 is a process flow diagram illustrating an example method as implemented in a donor node, according to some embodiments.
  • Figure 14 is a process flow diagram illustrating another example method as implemented in a donor node, according to some embodiments.
  • Figure 15 is a block diagram illustrating an example UE, according to some embodiments.
  • Figure 16 is a process flow diagram illustrating an example method as implemented in a UE, according to some embodiments.
  • Figure 17 illustrates an example telecommunication network connected to a host via an intermediate network, in accordance with some embodiments.
  • Figure 18 illustrates a host computer communicating over a partially wireless connection with, in accordance with some embodiments.
  • Figure 19 is a flowchart illustrating methods implemented in a communication system that includes a host computer, a base station, and a user equipment, in accordance with some embodiments.
  • Figure 20 is another flowchart illustrating methods implemented in a communication system that includes a host computer, a base station, and a user equipment, in accordance with some embodiments.
  • Figure 21 shows another flowchart illustrating methods implemented in a communication system that includes a host computer, a base station, and a user equipment, in accordance with some embodiments.
  • Figure 22 shows still another flowchart illustrating methods implemented in a communication system that includes a host computer, a base station, and a user equipment, in accordance with some embodiments.
  • Figure 23 is a block diagram illustrating functional components of an example network node, according to some embodiments.
  • Figure 24 is another block diagram illustrating functional components of an example network node, according to some embodiments.
  • Figure 25 is a block diagram illustrating functional components of an example UE, according to some embodiments.
  • the term “access IAB node” refers to the IAB node the UE is connected to, while “intermediate IAB node” refers to any IAB node between the access IAB node and the donor.
  • the techniques described herein equally apply to the case where the IAB node is connected in an EN-DC mode (i.e., LTE eNB as the master and an NR gNB as a secondary node).
  • the function here specified for the donor CU will be carried out by the LTE eNB, and since the CU-DU split is currently not available in LTE, the conditional release and reconfiguration messages described below are sent to the IAB-MT node, but with indications that the messages are not for the sake of the IAB node itself but for a given UE.
  • the method is applicable to any network that applies the split architecture, like the CU/DU, where the CP
  • RRC/PDCP is terminated at one node and an intermediate node terminates the lower layers. It should be understood that this document uses the term Conditional Handover (CHO) in the same way as Conditional Reconfiguration.
  • an IAB node can inform its child nodes when the IAB node has an RLF with its parent node and the child nodes can take further actions such as suspend transmission to that parent and/or perform re-establishment and resume transmission via another parent node.
  • Type 1 - “Plain” notification Indication that BH link RLF is detected by the IAB node.
  • Type 2 - “Trying to recover” Indication that BH link RLF is detected by the IAB node, and the IAB node is attempting to recover from it.
  • Type 3 “BH link recovered”: Indication that the BH link successfully recovers from RLF.
  • Type 4 “Recovery failure”: Indication that the BH link RLF recovery failure occurs.
  • the IAB node may send a type 1 or type 2 notification to its children node and in the meantime try to find an alternate parent/link. If the recovery fails, the IAB node either sends a type 4 (notification failure) message or turn of the radio or the transmission of essential system information. Between the two steps (between the sending of type 1/2 messages and type 3 messages), the children IAB node may just suspend transmission to their parent node that sent the notification, or they may try to find alternate parents.
  • an IAB node is just like any other gNB.
  • One approach is for the CU to transmit to the IAB node an RRC Release message, possibly including a suspend configuration with an I-RNTI (e.g., full or short I-RNTI), where the message is to be stored at the IAB node and only transmitted to the UE upon the detection of a failure at the link between the IAB node and its parent (i.e., the IAB node is not able to communicate with the CU anymore). Then, once that is provided to the UE, the UE can resume and transmits an RRC Resume Request including the I-RNTI so the context can be located and the UE can continue its connection with another node.
  • I-RNTI e.g., full or short I-RNTI
  • a benefit of this approach is that by allocating an I-RNTI and associating it to a context at the UE, the network enables the UE connected to the IAB node to connect to another DU/IAB node, upon a failure between the source IAB node and the CU.
  • Another benefit is that target nodes do not have to be prepared in advance since the context remains stored at the CU and may be fetched in case the UE resumes in another node.
  • a IAB node is configured with a conditional RRC Release message that is intended for a UE that is being served by the IAB node, as well as a trigger condition to send this RRC Release message.
  • the IAB node will store this RRC Release message and will transmit it to the UE only when the trigger condition is fulfilled, e.g., when the IAB node experiences BH RLF failure towards its parent node.
  • Embodiments of this approach include methods implemented by a first network node, operating as a donor central unit (e.g., a donor CU) in an Integrated access backhaul (IAB) network, providing connectivity for a user equipment (UE).
  • a donor central unit e.g., a donor CU
  • IAB Integrated access backhaul
  • UE user equipment
  • ⁇ Determining that the UE supports RRC INACTIVE and including in the RRC Release message a suspend configuration (i.e., including a suspendConfig as defined in TS 38.331); and performing at least one of the following actions:
  • I-RNTI such as full I-RNTI, or a short I-RNTI (as defined in TS 38.331), so the UE may resume after it has received the RRC Release message from the IAB node; • Providing to the UE with a Next Hop Chaining Counter (NCC);
  • NCC Next Hop Chaining Counter
  • RNA Notification Area configuration e.g., in case the first node wants to know when the UE camps in a cell not within a set of cells known at the first node;
  • Timer T380 value for periodic RNA Updates
  • That may be set to a rather low value by the first node (e.g., 1 second, new value introduced in RRC) as a way to trigger the UE resume immediately after it has received the RRC Release from the IAB node;
  • that redirect information is included in case the first network node wants the UE to select a cell in a given frequency after having received the RRC Release message.
  • the message can include a triggering condition, upon the fulfillment of which the IAB node should transmit the RRC Release like message to the UE, where the trigger condition could be a combination of one or more of these:
  • BH Backhaul
  • the IAB node has detected a significant signal quality drop on a backhaul link towards its parent node(s)
  • the IAB node has detected a significant congestion on the backhaul link towards its parent node(s)
  • the IAB node has failed to recover the BH link (e.g., on re-establishment failure, on fast MCG recovery failure, SCG recovery failure, etc.)
  • a timer value (e.g., txxx) specifying that the IAB node should start a timer with the provided value
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Release like message (i.e., the RRC Release like message is forwarded to the UE upon the expiry of this timer even if the other trigger conditions may not have been fulfilled at that time)
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Release like message, and if none of the trigger conditions are fulfilled by the time the timer has expired, the RRC Release like message will be deleted (i.e., never forwarded to the UE) o
  • the IAB node may send a confirmation of the deletion of the message to the CU, or the CU may explicitly infer that ( (i.e., the RRC Release like message is forwarded to the UE upon the expiry of this timer even if the other trigger conditions may not have been fulfilled at that time)
  • a non UE associated Fl-AP message after a UE has connected to the IAB node (where a multiple of RRC Release like messages destined for several UEs can be included in one message, each with the UE identity, e.g., Fl-AP UE Context IDs identifying the concerned UE) additional IEs are included in the Fl-AP messages to include the trigger condition(s) the RRC Release like message contained in a transparent container (e.g., OCTET STRING) Sending an update to the RRC Release like message intended to the UE:
  • a transparent container e.g., OCTET STRING
  • a second network node operating as an IAB node in an IAB network, providing connectivity for a UE.
  • These methods may include one or more of any of the following steps and/or features: o Receiving a message from a first network node (donor CU), that includes an RRC Release like message intended for the UE and at least an indication that the message is not to be directly transmitted/forwarded to the UE (i.e., its transmission to the UE is to be delayed).
  • the message may include a triggering condition, where the triggering condition can be one of the following:
  • the IAB node has detected a significant signal quality drop on a backhaul link towards its parent node(s)
  • the IAB node has detected a significant congestion on the backhaul link towards its parent node(s)
  • the IAB node has failed to recover the BH link (e.g., on re-establishment failure, on fast MCG recovery failure, SCG recovery failure, etc.)
  • a timer value (e.g., txxx)
  • these triggering conditions are pre-defined and possibly implemented in the IAB node (or specified in standard documents).
  • the IAB node upon receiving the RRC Release message and the indication that its transmission to the UE is to be delayed (e.g., transmission only upon fulfillment of a condition) the IAB node upon receiving the RRC Release message stores it and monitors the fulfillment of these pre-defined conditions.
  • OCTET STRING OCTET STRING
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Release like message and when this timer expires, the trigger conditions are considered to be fulfilled (regardless of the status of any other triggering conditions)
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Release like message, and if none of the trigger conditions are fulfilled by the time the timer has expired, the IAB node stops monitoring the other trigger conditions
  • the IAB node starts the timer only after one or more of the other trigger conditions are fulfilled, and wouldn’t take action associated with the fulfillment of the conditions until the timer expires. o Taking the following action upon the fulfillment of the trigger conditions: transmit the RRC Release like message to the UE Releasing the UE context and associated resources at the IAB node.
  • triggering conditions discussed above in connection with either of these two groups of methods may also be referred to as a triggering condition configuration, execution condition, or execution condition configuration.
  • a triggering condition may include any one or any combination of the following events:
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon detection of RLF in the backhaul link i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU-Donor);
  • the IAB node monitors the occurrence of RLF for the backhaul link and, if that occurs, the IAB node transmits the RRC Release message to the UE;
  • Signal quality on the backhaul link e.g., measured in terms of RSRP, RSRQ, SINR or any other measurement quantity
  • a parent node falls below a specified threshold (e.g., RSRP threshold, RSRQ threshold, SINR threshold);
  • the triggering condition transmitted from the CU-Donor to the IAB node can be a configuration of an Ax event, such as a reportConfig field of IE ReportConfigNR, or a measurement identifier (measld) associated to a measConfig of IE MeasConfig (i.e., having a reportConfig of IE ReportConfigNR and a measObject of IE MeasObjectNR);
  • the event is associated to the frequency of the serving cell associated to the backhaul link.
  • ⁇ In one embodiment that is possibly associated measurement object;
  • the triggering condition comprises the combination of multiple conditions, e.g., multiple measurement identifiers combined in an AND condition. For example, if the triggering condition is a list of measld(s) it means that the condition is considered as fulfilled is the conditions associated to all measld(s) are considered as fulfilled.
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon detection of a number of OOS events in the backhaul link i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU-Donor); Hence, upon reception of the RRC
  • the IAB node monitors the occurrence of OOS event for the backhaul link and, if that occurs, the IAB node transmits the RRC Release message to the UE; Notice that this is not exactly the same as the occurrence of RLF since herein the UE would receive the RRC Release message before an RLF in the BH link is possibly detected by the IAB node.
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon the detection of beam failure i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU- Donor);
  • the IAB node monitors the occurrence of beam failure for the backhaul link and, if beam failure is detected, the IAB node transmits the RRC Release message to the UE; Notice that this is not exactly the same as the occurrence of RLF since herein the UE would receive the RRC Release message before an RLF in the BH link is possibly detected by the IAB node;
  • Figure 10A shows a simplified signaling flow illustrating some of the embodiments above.
  • the target candidate CU could be another donor CU and the UE may be connected to it via another IAB node, or it could be the same as the source CU (in which case, the messages shown towards the target are not required).
  • the UE is initially connected to relay node IAB-1, which provides service to the UE through a donor DU and donor CU.
  • the donor CU sends a release message for the UE, illustrated in the figure as an RRC Release message, along with an indication of one or more triggering conditions.
  • the IAB stores the release message, and then monitors for the fulfillment of the triggering conditions.
  • RLF radio link failure
  • the UE sends an RRC Resume Request to a target CU/gnB, which retrieves the UE context from the previous donor CU and then sends an RRC Resume Complete message to the UE.
  • the RRC release message sent to the UE may include information directing the UE towards the target CU/gNB, in some embodiments, e.g., by identifying the gNB and/or a frequency for the UE to evaluate after its release.
  • the first node transmits to the IAB node an indication that the IAB node shall suspend the connection with the UE upon the fulfillment of a condition (this condition could be the same as discussed above, such as the detection of a BH RLF failure).
  • the IAB node upon the fulfillment of the condition, will then transmit to the UE a lower layer signal (e.g., using MAC CE) indicating to the UE that the UE shall initiate a re-establishment procedure.
  • the UE may have been pre- configured with a configuration that is activated by that MAC CE e.g., indicating at which frequency the UE shall select a cell while timer T311 is running.
  • the first network node stores the UE configuration and context even after having detected that it hast lost the connection with the IAB node (e.g., the UE’s C-RNTI and Physical Cell Identity, security context such as encryption and integrity protection keys, RRC configuration). The reason is that the first node knows that the UE may initiate a re- establishment procedure based on the conditional RRC release message sent earlier to the IAB node. Then, if the UE tries to re-establish in a cell within the first network node, the UE configuration is available, and the first network node can continue with the re-establishment procedure.
  • the UE may initiate a re- establishment procedure based on the conditional RRC release message sent earlier to the IAB node. Then, if the UE tries to re-establish in a cell within the first network node, the UE configuration is available, and the first network node can continue with the re-establishment procedure.
  • the release message described above is forwarded to UE prior to the detecting of any problem with the backhaul link, but not acted upon immediately by the UE. Instead, the UE monitors for the fulfillment of one or more trigger conditions associated with the message.
  • a trigger condition may be, simply, the receipt of a second message indicating that the earlier received release message should be acted upon.
  • embodiments of the techniques described herein also include methods implemented by a UE operating in an integrated access backhaul (IAB) network, where the UE is connected to a second network node (IAB node), that is being served by a first network node, a donor central unit (e.g., Donor-CU). These methods may include:
  • This message may be a medium access control (MAC) control element (CE), a downlink control information (DCI) message, or lower layer signaling, for example.
  • MAC medium access control
  • DCI downlink control information
  • the second message may be transmitted by the IAB node upon the fulfillment of a trigger condition, where the trigger condition may either be configured by the CU-Donor or the determined by the IAB node.
  • one benefit of the approaches described above is that by allocating an I- RNTI and associating it to a context at the UE, the network enables the UE connected to the IAB node to connect to another DU/IAB node, upon a failure between the source IAB node and the CU.
  • Another benefit is that target nodes do not have to be prepared in advance since the context remains stored at the CU and, may be fetched in case the UE resumes in another node.
  • Techniques similar to those described above can be used to enable some level of service continuity via handover during the handling of the (legacy) UEs that are directly being served by the IAB node experiencing a BH RLF with a parent link, without the need for the IAB node to turn itself off or turn off the transmission of essential system information and forcing the UE to perform a re-establishment or NAS recovery via IDLE mode.
  • This can be done, for example, by the IAB node being configured with at least one RRC Reconfiguration message (e.g., including a reconfiguration with sync) for at least one target candidate, where the RRC Reconfiguration message is intended for a UE that is being served by the IAB node.
  • this is done by transmitting to the IAB node a conditional reconfiguration message (e.g., an RRC Reconfiguration message) to be forwarded to the UE, where the conditional reconfiguration message comprising at least one RRC Reconfiguration message per target candidate (e.g., including a reconfiguration with sync).
  • the message is immediately provided to the UE that is being served by the IAB node.
  • CHO conditional handover
  • the UE receives the conditional reconfiguration message (including at least one RRC Reconfiguration per target candidate to be stored) and, upon detecting an RLF with the IAB node, it performs cell selection while timer T311 is running and, if the selected cell is one of the cells for which the UE has a stored RRC Reconfiguration message, the UE applies the message, i.e., it executes a conditional handover, otherwise it performs a re-establishment.
  • the detection of RLF at the UE may be forced by the IAB node, e.g., by the IAB node stopping the transmission of radio link monitoring (RLM) reference signals.
  • RLM radio link monitoring
  • the RRC reconfiguration is transmitted immediately to the UE (i.e., transmitted to the UE upon reception from the parent node) and the UE stores the configuration and applies the configuration based on a second indicator or other information received from the IAB node.
  • the IAB node upon detecting a backhaul RLF, may send a MAC CE (DCI, or any other L1/L2 indication) indicating to the UE to start applying the CHO configuration, the UE considering the configuration was just received at that moment.
  • the second indication from the IAB node could include information about one or more preferred target cells the UE has to connect to (i.e., the UE will choose the RRC reconfiguration that includes the indicated cell/s as a target).
  • a trigger condition could be included in the conditional reconfiguration message that is forwarded to the UE.
  • the UE may start monitoring the trigger conditions but will not execute the reconfiguration message when the conditions are met. Rather, it will wait until it experiences an RLF with the IAB node (or the reception of an indicator from the IAB node such as a MAC CE), and only then will execute the configuration that has a trigger condition fulfilled.
  • the parent node/CU determines whether to configure the IAB node with one or more RRC Reconfiguration(s) or with an RRC Release message, wherein the configured message is to be provided to the UE upon the IAB node detecting a backhaul RLF.
  • the determination between whether to transmit to the UE one or more RRC Reconfiguration(s) versus an RRC Release message could be based on quality information per cell at the IAB node. For example, if the IAB node is aware that a cell is the best on a given frequency and the IAB node has an RRC Reconfiguration associated to it, that is transmitted.
  • the IAB node transmits the RRC Release (so that the UE can select a cell).
  • Conditional Handover (CHO) in the same way as a Conditional Reconfiguration.
  • Conditional Reconfiguration including its fields and information elements (IEs) is defined in 3GPP TS 38.331, an excerpt of which is shown below: begin excerpt from 3 GPP TS 38.331 - ConditionalReconfiguration
  • the IE ConditionalReconfiguration is used to add, modify and release the configuration of conditional configuration.
  • CondConfigToRemoveList-rl6 SEQUENCE (SIZE (1.. maxNrofCondCells)) OF CondConfigId-rl6
  • the IE CondConfigld is used to identify a CHO or CPC configuration.
  • the IE CHO-ConfigToAddModList concerns a list of conditional configurations to add or modify, with for each entry the cho-Configld and the associated condExecutionCond and condRRCReconfig.
  • CondConfigT o AddModList-r 16 :: SEQUENCE (SIZE (1.. maxNrofCondCells)) OF CondConfigT o AddMod-r 16
  • CondConfigT o AddMod-r 16 :: SEQUENCE ⁇ condConfigld-r 16 CondConfigld-r 16, condExecutionCond-r 16 SEQUENCE (SIZE (1..2)) OF Measld OPTIONAL,
  • embodiments of the techniques include additional methods implemented by a first network node, operating as a donor central unit (e.g., a donor CU) in an Integrated access backhaul (IAB) network, providing connectivity for a user equipment (UE).
  • a donor central unit e.g., a donor CU
  • IAB Integrated access backhaul
  • the message including at least an indication that the message is not to be directly transmitted/forwarded to the UE (i.e., its transmission to the UE is to be delayed).
  • the message can be provided together with a triggering condition, upon the fulfillment of which the IAB node should transmit at least one of the RRC Reconfiguration messages to the UE, where the trigger condition could be a combination of one or more of these:
  • the IAB node has detected a significant signal quality drop on a backhaul link towards its parent node(s)
  • the IAB node has detected a significant congestion on the backhaul link towards its parent node(s)
  • the IAB node has failed to recover the BH link (e.g., on re establishment failure, on fast MCG recovery failure, SCG recovery failure, etc.)
  • a timer value (e.g., txxx) specifying that the IAB node should start a timer with the provided value o
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Reconfiguration like message (i.e., the RRC Reconfiguration like message is forwarded to the UE upon the expiry of this timer even if the other trigger conditions may not have been fulfilled at that time) o
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Reconfiguration like message, and if none of the trigger conditions are fulfilled by the time the timer has expired, the RRC Reconfiguration like message will be deleted (i.e., never forwarded to the UE)
  • the IAB node may send a confirmation of the deletion of the message to the CU, or the CU may explicitly infer that (i.e., the RRC Reconfiguration like message is forwarded to the UE upon the expiry of this timer even if the other trigger conditions may not have been fulfilled at that time) o
  • the IAB node starts the timer only after one or more of the other trigger conditions are fulfilled (i.e., the RRC Reconfiguration like message is forwarded to the UE txxx seconds after the fulfillment of one or more trigger conditions)
  • a measurement configuration to the UE that is associated with the RRC Reconfiguration could also be included (i.e., when/if the UE receives RRC Reconfiguration(s) with associated measurement configuration, it will apply that configuration only when the measurement triggering conditions are fulfilled)
  • IAB node e.g., UE Context Modification Request, DL RRC Message Transfer
  • a non UE associated Fl-AP message after a UE has connected to the IAB node (where a multiple of RRC Reconfiguration like messages destined for several UEs can be included in one message, each with the UE identity, e.g., Fl-AP UE Context IDs identifying the concerned UE)
  • Reconfiguration message associated with target #2 is to be sent when/if the triggering conditions are fulfilled
  • this can be sent to the IAB node using UE associated or non-UE associated Fl-AP messages.
  • Other embodiments are methods implemented by a second network node, operating as an IAB node in an IAB network, providing connectivity for a UE. These methods, which may complement the methods described above, may include one or more of any of the following steps and/or features: Receiving a message from a first network node (donor CU), that includes at least one RRC Reconfiguration like message intended for the UE and at least an indication that the message is not to be directly transmitted/forwarded to the UE (i.e., its transmission to the UE is to be delayed).
  • the message may include a triggering condition, where the triggering condition can be one of the following:
  • the IAB node has detected a significant signal quality drop on a backhaul link towards its parent node(s)
  • the IAB node has detected a significant congestion on the backhaul link towards its parent node(s)
  • the IAB node has failed to recover the BH link (e.g., on re-establishment failure, on fast MCG recovery failure, SCG recovery failure, etc.)
  • a timer value (e.g., txxx) o
  • these conditions are pre-defined and possibly implemented in the IAB node (or specified in standard documents).
  • the IAB node upon receiving the RRC Reconfiguration message and the indication that its transmission to the UE is to be delayed (e.g., transmission only upon fulfillment of a condition) the IAB node upon receiving the RRC Reconfiguration message stores it and monitors the fulfillment of the condition.
  • ⁇ the at least one RRC Reconfiguration like message contained in a transparent container (e.g, OCTET STRING)
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Reconfiguration like message and when this timer expires, the trigger conditions are considered to be fulfilled (regardless of the status of any other triggering conditions)
  • the IAB node starts the timer with value txxx immediately on the reception of the RRC Reconfiguration like message, and if none of the trigger conditions are fulfilled by the time the timer has expired, the IAB node stops monitoring the other trigger conditions
  • the IAB node starts the timer only after one or more of the other trigger conditions are fulfilled, and wouldn’t take action associated with the fulfillment of the conditions until the timer expires. Taking the following action upon the fulfillment of the trigger conditions:
  • triggering conditions discussed above in connection with either of these two groups of methods may also be referred to as a triggering condition configuration, execution condition, or execution condition configuration.
  • a triggering condition may include any one or any combination of the following events:
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon detection of RLF in the backhaul link i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU-Donor);
  • the IAB node monitors the occurrence of RLF for the backhaul link and, if that occurs, the IAB node transmits the RRC Release message to the UE;
  • Signal quality on the backhaul link e.g., measured in terms of RSRP, RSRQ, SINR or any other measurement quantity
  • a parent node falls below a specified threshold (e.g., RSRP threshold, RSRQ threshold, SINR threshold);
  • the triggering condition transmitted from the CU-Donor to the IAB node can be a configuration of an Ax event, such as a reportConfig field of IE ReportConfigNR, or a measurement identifier (measld) associated to a measConfig of IE MeasConfig (i.e., having a reportConfig of IE ReportConfigNR and a measObject of IE MeasObjectNR);
  • the triggering condition comprises the combination of multiple conditions, e.g., multiple measurement identifiers combined in an AND condition. For example, if the triggering condition is a list of measld(s) it means that the condition is considered as fulfilled is the conditions associated to all measld(s) are considered as fulfilled.
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon detection of a number of OOS events in the backhaul link i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU-Donor);
  • the IAB node monitors the occurrence of OOS event for the backhaul link and, if that occurs, the IAB node transmits the RRC Release message to the UE; Notice that this is not exactly the same as the occurrence of RLF since herein the UE would receive the RRC Release message before an RLF in the BH link is possibly detected by the IAB node.
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon the start of timer T310 for the radio Ink monitoring of the backhaul link i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU-Donor);
  • the IAB node monitors the occurrence of OOS event for the backhaul link and, if timer T310 is to be started, the IAB node transmits the RRC Release message to the UE; Notice that this is not exactly the same as the occurrence of RLF since herein the UE would receive the RRC Release message before an RLF in the BH link is possibly detected by the IAB node (RLF would only be considered as detected if timer T310 expires).
  • the triggering condition may be an indication (e.g., flag, or field) from the CU-Donor to the IAB node, indicating that the RRC Release message is to be transmitted to the UE upon the detection of beam failure i.e., in the link between the first and the second nodes (e.g., the IAB node and the CU-
  • the IAB node upon reception of the RRC Release message for the UE, the IAB node monitors the occurrence of beam failure for the backhaul link and, if beam failure is detected, the IAB node transmits the RRC Release message to the UE; Notice that this is not exactly the same as the occurrence of RLF since herein the UE would receive the RRC Release message before an RLF in the BH link is possibly detected by the IAB node;
  • Figure 10B shows a simplified signaling flow illustrating some of the embodiments above.
  • the target candidate CU could be another donor CU and the UE may be connected to it via another IAB node, or it could be the same as the source CU (in which case, the messages shown towards the target are not required).
  • the UE is initially connected to relay node IAB-1, which provides service to the UE through a donor DU and donor CU.
  • the donor CU sends a conditional handover (CHO) request for the UE to the target candidate CU/gNB, which responds with a CHO Request Ack, including an RRC Reconfiguration for the UE.
  • the donor CU then sends a conditional reconfiguration message for the UE to the relay node IAB-1.
  • This conditional reconfiguration message is illustrated in the figure as an RRC Reconfiguration message, along with an indication of one or more triggering conditions. Rather than delivering this message to the UE right away, the IAB stores the conditional reconfiguration message, and then monitors for the fulfillment of the triggering conditions.
  • RLF radio link failure
  • the UE Upon receipt of the reconfiguration message, the UE then applies the message, containing a reconfiguration with sync. Then, as shown in Figure 10B, the UE sends an RRC Reconfiguration Complete message to a target CU/gnB, which sends a Handover Success message to the donor CU. The donor CU then needs to release any resources it has reversed on other target candidate nodes, via CHO requests.
  • the UE may have been pre-configured with a CHO configuration (which may contain reconfiguration towards several targets) that is activated by that MAC CE.
  • the MAC CE may contain an additional information such as which CHO target the reconfiguration is directed to, e.g., indicating at which frequency the UE shall select a cell while timer T311 is running.
  • the first network node stores the UE configuration and context even after having detected that it lost the connection with the IAB node (e.g., UE’s C-RNTI and Physical Cell Identity, security context such as encryption and integrity protection keys, RRC configuration). The reason is that the first node knows that the UE may initiate a handover (HO) towards a neighbor node based on an RRC reconfiguration that was sent earlier to the IAB node (which the IAB node will forward when it detects a BH RLF, for example).
  • UE e.g., UE’s C-RNTI and Physical Cell Identity, security context such as encryption and integrity protection keys, RRC configuration.
  • conditional reconfiguration message described above is forwarded to the UE prior to the detecting of any problem with the backhaul link, but not acted upon immediately by the UE. Instead, the UE monitors for the fulfillment of one or more trigger conditions associated with the message.
  • a trigger condition may be, simply, the receipt of a second message indicating that the earlier received release message should be acted upon.
  • embodiments of the techniques described herein also include methods implemented by a UE operating in an integrated access backhaul (IAB) network, where the UE is connected to a second network node (IAB node), that is being served by a first network node, a donor central unit (e.g., Donor-CU).
  • IAB integrated access backhaul
  • Donor-CU donor central unit
  • This message may be a medium access control (MAC) control element (CE), a downlink control information (DCI) message, or lower layer signaling, for example.
  • the second message may be transmitted by the IAB node upon the fulfillment of a trigger condition, where the trigger condition may either be configured by the CU-Donor or the determined by the IAB node.
  • FIG 11 shows a network node 30 that may be configured to carry out all or parts of one or more of these disclosed techniques. More particularly, network node 30, which in the illustrated example is a radio network node (because it includes a radio for communicating with one or more UEs or MTs), may perform those operations attributed in the above discussion to either the first network node, e.g., acting as a donor node, or the second network node, e.g., acting as a relay node, in various embodiments.
  • the first network node e.g., acting as a donor node
  • the second network node e.g., acting as a relay node
  • some of the operations attributed to the first or second network nodes may be performed in a network node separate from a node containing radio functionality, e.g., all or partly in the “cloud.”
  • a network node may have a structure like the network node 30 illustrated in Figure 11, but without the transceiver circuitry 36 and antennas 34, for example.
  • the functionality attributed to the first and second network nodes in the discussion above may be distributed among several different network nodes, in various ways, especially given the various ways that base station functionality may be distributed, e.g., as in the split-gNB model (with CU and DU logical nodes) described above.
  • Network node 30 may be an evolved Node B (eNodeB), Node B or gNB. While a radio network node 30 is shown in Figure 11, the operations can be performed by other kinds of network nodes, including a radio network node such as base station, radio base station, base transceiver station, base station controller, network controller, NR base station (BS), Multi-cell/multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH), or a multi-standard BS (MSR BS).
  • a radio network node such as base station, radio base station, base transceiver station, base station controller, network controller, NR base station (BS), Multi-cell/multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH), or a multi-standard BS (MSR BS).
  • MCE Multi-cell/multicast Coordination Entity
  • RRU Remote Radio Unit
  • Network node 30 may also, in some cases, be a core network node (e.g., MME, SON node, a coordinating node, positioning node, MDT node, etc.), or even an external node (e.g., 3rd party node, a node external to the current network), etc.
  • Network node 30 may also comprise test equipment.
  • network node 30 will be described as being configured to operate as a cellular network access node in an LTE network or NR network.
  • the network node 30 will perform the role of a relay node, e.g., in an IAB deployment.
  • the network node 30 may perform the role of a donor node, again in an IAB deployment in some example.
  • all or parts of the techniques described herein can be implemented in the RRC layer.
  • the RRC layer could be implemented by one or more network nodes in a cloud environment and hence some embodiments can be implemented in a cloud environment.
  • Network node 30 facilitates communication between wireless terminals (e.g., UEs), other network access nodes and/or the core network.
  • Network node 30 may include communication interface circuitry 38 that includes circuitry for communicating with other nodes in the core network, radio nodes, and/or other types of nodes in the network for the purposes of providing data and/or cellular communication services.
  • Some embodiments of network node 30 communicate with wireless devices using antennas 34 and transceiver circuitry 36.
  • Transceiver circuitry 36 may include transmitter circuits, receiver circuits, and associated control circuits that are collectively configured to transmit and receive signals according to a radio access technology, for the purposes of providing cellular communication services.
  • Network node 30 also includes one or more processing circuits 32 that are operatively associated with the transceiver circuitry 36 and, in some cases, the communication interface circuitry 38.
  • Processing circuitry 32 comprises one or more digital processors 42, e.g., one or more microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Complex Programmable Logic Devices (CPLDs), Application Specific Integrated Circuits (ASICs), or any mix thereof. More generally, processing circuitry 32 may comprise fixed circuitry, or programmable circuitry that is specially configured via the execution of program instructions implementing the functionality taught herein, or some mix of fixed and programmed circuitry.
  • Processor 42 may be multi-core, i.e., having two or more processor cores utilized for enhanced performance, reduced power consumption, and more efficient simultaneous processing of multiple tasks.
  • Processing circuitry 32 also includes a memory 44.
  • Memory 44 stores one or more computer programs 46 and, optionally, configuration data 48.
  • Memory 44 provides non-transitory storage for the computer program 46 and it may comprise one or more types of computer-readable media, such as disk storage, solid-state memory storage, or any mix thereof.
  • “non-transitory” means permanent, semi-permanent, or at least temporarily persistent storage and encompasses both long-term storage in non-volatile memory and storage in working memory, e.g., for program execution.
  • memory 44 comprises any one or more of SRAM, DRAM, EEPROM, and FLASH memory, which may be in processing circuitry 32 and/or separate from processing circuitry 32.
  • Memory 44 may also store any configuration data 48 used by the network access node 30.
  • Processing circuitry 32 may be configured, e.g., through the use of appropriate program code stored in memory 44, to carry out one or more of the methods and/or signaling processes detailed herein.
  • Processing circuitry 32 of the network node 30 is configured, according to some embodiments, to perform all or part of the techniques described herein for one or more network nodes of a wireless communication system, including, for example, the methods described above for when the network node 30 is operating as a relay node serving a UE and relaying communications between the EfE and a core network, via a donor network.
  • These methods may include, in such embodiments, the step of receiving, from the donor network node, a message for conditional delivery to the EfE, the message including or being associated with one or more triggering conditions. These methods may further comprise determining that at least one of the triggering conditions is fulfilled and, responsive to this determination, forwarding the message to the EfE.
  • This message may be a release message instructing the EfE to release its current radio connection, in some embodiments. In other embodiments, this message may instead be a first connection reconfiguration message.
  • these methods may also or instead include the methods described above for when the network node 30 is operating as a donor network node serving a UE via at least a first relay node relaying communications between the UE and the donor network node.
  • the methods may include the steps of preparing a message for conditional delivery by the first relay node to the UE, the message including or being associated with one or more triggering conditions, and sending the message to the first relay node, where the message includes or is associated with an indication that the message is not to be delivered until at least one of the one or more triggering conditions is fulfilled.
  • the message may be a release message instructing the UE to release its current radio connection, in some embodiments. In others, the message may be a first connection reconfiguration message.
  • the processing circuitry 32 of network node 30 is, in some embodiments, configured to perform all or parts of a method 1200, shown by the flowchart of Figure 12, which illustrates an example method carried out by a relay node serving a UE and relaying communications between the UE and a core network, via a donor network node.
  • the method comprises receiving, from the donor network node, a message for conditional delivery to the UE, the message including or being associated with one or more triggering conditions.
  • the method further comprises determining that at least one of the triggering conditions is fulfilled, as shown at block 1220.
  • the method further comprises, responsive to this determination, forwarding the message to the UE, as shown at block 1230.
  • the message may be a release message instructing the UE to release its current radio connection, in some embodiments.
  • the message may be a RRC Release message, for example.
  • the message may comprise redirection information directing the UE to select a cell at a given frequency.
  • the message may instead be a first connection reconfiguration message.
  • the method further comprises releasing a UE context for the UE, at the relay node, upon or after forwarding the message to the UE. This is shown at block 1250.
  • the message includes or is associated with a timer value.
  • the method may further comprise starting a timer, where determining that at least one of the triggering conditions is fulfilled comprises determining that the timer has expired.
  • the starting of the timer is illustrated at block 1215, which, like block 1250, is illustrated with a dashed outline to indicate that it need not be present in all instances or embodiments of the illustrated method.
  • the relay node may start the timer upon receiving the message, or start the timer upon fulfillment of an intermediate condition included in or associated with the message.
  • At least one of the one or more triggering conditions is predefined in the relay node, prior to receiving the message.
  • the method shown in Figure 12 may comprise receiving an indication of at least one of the one or more triggering conditions from the donor network node upon or after connection of the UE to the relay node, prior to receiving the message. This is shown at block 1205 of Figure 12.
  • the one or more triggering conditions may include one or more of any one or more of the following: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; and a failure to recover a backhaul link toward a parent node after detecting a failure on the backhaul link.
  • the method may comprise receiving an update message from the donor network node, the update message indicating a change in one or more trigger conditions and/or indicating one or more additional trigger conditions. This is shown at block 1212 in Figure 12.
  • the method in these embodiments may further comprise updating the one or more trigger conditions in accordance with the update message, as shown at block 1214.
  • the determination that at least one of the triggering conditions is fulfilled may comprise determining that at least one of the triggering conditions as updated by the update message is fulfilled.
  • the processing circuitry 32 of network node 30 may, in some embodiments, also or instead be configured to perform all or parts of a method 1300, shown by the flowchart of Figure 13, which illustrates an example method carried out by a donor network node serving a UE, via at least a first relay node relaying communications between the UE and the donor network node.
  • this method comprises preparing a message for conditional delivery by the first relay node to the UE, this message including or being associated with one or more triggering conditions.
  • the method further comprises sending the message to the first relay node, as shown at block 1320, with the message including or being associated with an indication that the message is not to be delivered until at least one of the one or more triggering conditions is fulfilled.
  • the message may be a release message instructing the UE to release its current radio connection, such as an RRC Release message.
  • this message may instead be a connection reconfiguration message, e.g., and RRC Reconfiguration message.
  • preparing the message may comprise determining that the UE does not support an RRC INACTIVE state and omitting a suspend configuration indication from the message in response to said determining. In other embodiments or instances, preparing the message may instead comprise determining that the UE does support an RRC INACTIVE state and including a suspend configuration indication in the message in response to said determining.
  • preparing the message may further comprise at least one of the following: assigning to the UE at least one Inactive State Radio Network Temporary Identifier, I-RNTI, for use by the UE when resuming a connection after receiving the message from the relay node; providing to the UE a next hop chaining counter (NCC); and including redirection information in the message.
  • I-RNTI Inactive State Radio Network Temporary Identifier
  • the message includes or is associated with a timer value for use by the relay node for starting a timer, where expiration of the timer at the relay node is one of the one or more trigger conditions.
  • at least one of the one or more triggering conditions is predefined in the relay node, prior to the sending of the message to the relay node.
  • the method further comprises sending an indication of at least one of the one or more triggering conditions to the relay node upon or after connection of the UE to the relay node, prior to sending the message. This is shown at block 1305.
  • the one or more triggering conditions may include one or more of any one or more of the following, in various embodiments or instances: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; and a failure to recover a backhaul link toward a parent node after failure of the backhaul link.
  • the method may further comprise sending an update message to the relay node, as shown at block 1330, where the update message indicates a change in one or more trigger conditions and/or indicating one or more additional trigger conditions.
  • the method may further comprise receiving a context retrieve request for the UE from another network node, after sending the message, as shown at block 1340.
  • the method may further comprise sending a UE context for the UE to the another network node and releasing the UE context for the UE and associated resources, as shown at blocks 1350 and 1360.
  • the method may further comprise receiving a measurement report from the UE and/or load information for each of one or more network nodes, and sending a message to the relay node indicating the first connection reconfiguration message from a plurality of connection reconfiguration messages for the UE sent to the UE, in response to the measurement report from the UE and/or the load information.
  • the processing circuitry 32 of network node 30 may, in some embodiments, also or instead be configured to perform all or parts of a method 1400, shown by the flowchart of Figure 14, which illustrates another example method carried out by a donor network node serving a UE, via at least a first relay node relaying communications between the UE and the donor network node.
  • this method comprises sending a conditional reconfiguration message to the UE, via the first relay node, the conditional reconfiguration message comprising at least one reconfiguration message associated with a corresponding target network node.
  • This method further comprises separately sending an indication to the UE, via the relay node, the indication indicating to the UE that the UE is to start applying the conditional reconfiguration message, as shown at block 1420.
  • FIG. 15 illustrates a diagram of a UE 50 configured to carry out one or more of the disclosed techniques, according to some embodiments.
  • UE 50 may be considered to represent any wireless devices or mobile terminals that may operate in a network, such as a UE in a cellular network.
  • Other examples may include a communication device, target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine communication (M2M), a sensor equipped with UE, PDA (personal digital assistant), tablet, IPAD tablet, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), etc.
  • D2D device to device
  • M2M machine to machine communication
  • PDA personal digital assistant
  • tablet IPAD tablet
  • smart phone laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles
  • CPE Customer Premises Equipment
  • UE 50 is configured to communicate with a network node or base station in a wide-area cellular network via antennas 54 and transceiver circuitry 56.
  • Transceiver circuitry 56 may include transmitter circuits, receiver circuits, and associated control circuits that are collectively configured to transmit and receive signals according to a radio access technology, for the purposes of using cellular communication services.
  • This radio access technology can be NR or LTE for the purposes of this discussion, and the network node or base station to which the UE 50 connects may be a relay node, e.g., an IAB access node.
  • UE 50 also includes one or more processing circuits 52 that are operatively associated with the radio transceiver circuitry 56.
  • Processing circuitry 52 comprises one or more digital processing circuits, e.g., one or more microprocessors, microcontrollers, DSPs, FPGAs, CPLDs, ASICs, or any mix thereof. More generally, processing circuitry 52 may comprise fixed circuitry, or programmable circuitry that is specially adapted via the execution of program instructions implementing the functionality taught herein or may comprise some mix of fixed and programmed circuitry. Processing circuitry 52 may be multi-core.
  • Processing circuitry 52 also includes a memory 64.
  • Memory 64 stores one or more computer programs 66 and, optionally, configuration data 68.
  • Memory 64 provides non-transitory storage for computer program 66 and it may comprise one or more types of computer-readable media, such as disk storage, solid-state memory storage, or any mix thereof.
  • memory 64 comprises any one or more of SRAM, DRAM, EEPROM, and FLASH memory, which may be in processing circuitry 52 and/or separate from processing circuitry 52.
  • Memory 64 may also store any configuration data 68 used by UE 50.
  • Processing circuitry 52 may be configured, e.g., through the use of appropriate program code stored in memory 64, to carry out one or more of the methods and/or signaling processes detailed herein.
  • processing circuitry 52 of the UE 50 may be configured, according to some embodiments, to perform any methods that support or correspond with the techniques described herein for the network nodes or first base station.
  • This method may further comprise, responsive to fulfilment of a trigger event, performing cell selection, as shown at block 1620.
  • the method may further comprises, as shown at block 1630, responsive to selecting a cell corresponding to the target network node, performing a conditional handover according to the reconfiguration message associated with the target network node.
  • the UE may be configured to carry out a method that includes a step of receiving, from a relay node serving the UE and relaying communications between the UE and a core network, via a donor network node, a conditional release message, where the conditional release message includes or is associated with one or more triggering conditions.
  • This method may further comprise determining that at least one of the one or more triggering conditions is fulfilled and, in response to this determination, releasing the UE’s connection to the relay node according to the conditional release message.
  • the conditional release message comprises redirection information directing the UE to select a cell at a given frequency.
  • the trigger event is radio link failure with the relay node.
  • the trigger event is receipt of an indication indicating to the UE that the UE is to start applying the conditional reconfiguration message or the conditional release message. This may be in the form of a MAC CE, a DCI message, or other lower layer signaling.
  • the indication identifies a target network node or a cell associated with a target network node for conditional handover.
  • the reconfiguration message includes or is associated with one or more trigger conditions, and wherein performing the conditional handover according to the reconfiguration message is further conditioned on at least one of the one or more trigger conditions being met.
  • Figure 17 illustrates a communication system that includes a telecommunication network 1710, such as a 3GPP-type cellular network, which comprises an access network 1711, such as a radio access network, and a core network 1714.
  • the access network 1711 comprises a plurality of base stations 1712a, 1712b, 1712c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area
  • Each base station 1712a, 1712b, 1712c is connectable to the core network 1714 over a wired or wireless connection 1715.
  • a first UE 1791 located in coverage area 1713c is configured to wirelessly connect to, or be paged by, the corresponding base station 1712c.
  • a second UE 1792 in coverage area 1713a is wirelessly connectable to the corresponding base station 1712a. While a plurality of UEs 1791, 1792 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 1712.
  • the telecommunication network 1710 is itself connected to a host computer 1730, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm.
  • the host computer 1730 may be under the ownership or control of a service provider or may be operated by the service provider or on behalf of the service provider.
  • the connections 1721, 1722 between the telecommunication network 1710 and the host computer 1730 may extend directly from the core network 1714 to the host computer 1730 or may go via an optional intermediate network 1720.
  • the intermediate network 1720 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 1720, if any, may be a backbone network or the Internet; in particular, the intermediate network 1720 may comprise two or more sub-networks (not shown).
  • the communication system of Figure 17 enables connectivity between one of the connected UEs 1791, 1792 and the host computer 1730.
  • the connectivity may be described as an over-the-top (OTT) connection 1750.
  • the host computer 1730 and the connected UEs 1791, 1792 are configured to communicate data and/or signaling via the OTT connection 1750, using the access network 1711, the core network 1714, any intermediate network 1720 and possible further infrastructure (not shown) as intermediaries.
  • the OTT connection 1750 may be transparent in the sense that the participating communication devices through which the OTT connection 1750 passes are unaware of routing of uplink and downlink communications.
  • a base station 1712 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 1730 to be forwarded (e.g., handed over) to a connected UE 1791. Similarly, the base station 1712 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1791 towards the host computer 1730.
  • a host computer 1810 comprises hardware 1815 including a communication interface 1816 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 1800.
  • the host computer 1810 further comprises processing circuitry 1818, which may have storage and/or processing capabilities.
  • the processing circuitry 1818 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the host computer 1810 further comprises software 1811, which is stored in or accessible by the host computer 1810 and executable by the processing circuitry 1818.
  • the software 1811 includes a host application 1812.
  • the host application 1812 may be operable to provide a service to a remote user, such as a UE 1830 connecting via an OTT connection 1850 terminating at the UE 1830 and the host computer 1810. In providing the service to the remote user, the host application 1812 may provide user data which is transmitted using the OTT connection 1850.
  • the communication system 1800 further includes a base station 1820 provided in a telecommunication system and comprising hardware 1825 enabling it to communicate with the host computer 1810 and with the UE 1830.
  • the hardware 1825 may include a communication interface 1826 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 1800, as well as a radio interface 1827 for setting up and maintaining at least a wireless connection 1870 with a UE 1830 located in a coverage area (not shown in Figure 18) served by the base station 1820.
  • the communication interface 1826 may be configured to facilitate a connection 1860 to the host computer 1810.
  • connection 1860 may be direct or it may pass through a core network (not shown in Figure 18) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system.
  • the hardware 1825 of the base station 1820 further includes processing circuitry 1828, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the base station 1820 further has software 1821 stored internally or accessible via an external connection.
  • the communication system 1800 further includes the UE 1830 already referred to. Its hardware 1835 may include a radio interface 1837 configured to set up and maintain a wireless connection
  • the hardware 1835 of the UE 1830 further includes processing circuitry 1838, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the UE 1830 further comprises software 1831, which is stored in or accessible by the UE 1830 and executable by the processing circuitry 1838.
  • the software 1831 includes a client application 1832.
  • the client application 1832 may be operable to provide a service to a human or non human user via the UE 1830, with the support of the host computer 1810.
  • an executing host application 1812 may communicate with the executing client application 1832 via the OTT connection 1850 terminating at the UE 1830 and the host computer 1817.
  • the client application 1832 may receive request data from the host application 1812 and provide user data in response to the request data.
  • the OTT connection 1850 may transfer both the request data and the user data.
  • the client application 1832 may interact with the user to generate the user data that it provides.
  • the host computer 1810, base station 1820 and UE 1830 illustrated in Figure 18 may be identical to the host computer 1730, one of the base stations 1712a, 1712b, 1712c and one of the UEs 1791, 1792 of Figure 17, respectively. This is to say, the inner workings of these entities may be as shown in Figure 18 and independently, the surrounding network topology may be that of F igure 17.
  • the wireless connection 1870 between the UE 1830 and the base station 1820 is in accordance with the teachings of the embodiments described throughout this disclosure, such as provided by nodes such as UE 50 and network node 30, along with the corresponding methods 1200, 1300, 1400.
  • the embodiments described herein allow IAB nodes and UEs to more efficiently respond to and react to network problems, such as the failure of a backhaul link, and more particularly provide more efficient release techniques in the event of such a failure.
  • the teachings of these embodiments may improve the reliability, data rate, capacity, latency and/or power consumption for the network and UE 1830 using the OTT connection 1850 for emergency warning systems and thereby provide benefits such as more efficient and targeted emergency messaging that saves on network and UE resources while improving the ability of users to take safe action.
  • a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve.
  • the measurement procedure and/or the network functionality for reconfiguring the OTT connection 1850 may be implemented in the software 1811 of the host computer 1810 or in the software 1831 of the UE 1830, or both.
  • sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 1850 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 1811, 1831 may compute or estimate the monitored quantities.
  • the reconfiguring of the OTT connection 1850 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 1820, and it may be unknown or imperceptible to the base station 1820. Such procedures and functionalities may be known and practiced in the art.
  • measurements may involve proprietary UE signaling facilitating the host computer’s 1810 measurements of throughput, propagation times, latency and the like.
  • the measurements may be implemented in that the software 1811, 1831 causes messages to be transmitted, in particular, empty or ‘dummy’ messages, using the OTT connection 1850 while it monitors propagation times, errors etc.
  • Figure 19 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 17 and 18. For simplicity of the present disclosure, only drawing references to Figure 19 will be included in this section.
  • the host computer provides user data.
  • the host computer provides the user data by executing a host application.
  • the host computer initiates a transmission carrying the user data to the UE.
  • the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the UE executes a client application associated with the host application executed by the host computer.
  • Figure 20 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 17 and 18. For simplicity of the present disclosure, only drawing references to Figure 20 will be included in this section.
  • the host computer provides user data.
  • the host computer provides the user data by executing a host application.
  • the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the UE receives the user data carried in the transmission.
  • FIG. 21 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 17 and 18. For simplicity of the present disclosure, only drawing references to Figure 21 will be included in this section.
  • the UE receives input data provided by the host computer.
  • the UE provides user data.
  • the UE provides the user data by executing a client application.
  • the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer.
  • the executed client application may further consider user input received from the user.
  • the UE initiates, in an optional third substep 2130, transmission of the user data to the host computer.
  • the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the functional implementation includes a receiving module 2302 for receiving, from the donor network node, a message for conditional delivery to the UE, the message including or being associated with one or more triggering conditions.
  • the implementation also includes a determining module 2304 for determining that at least one of the triggering conditions is fulfilled.
  • the implementation also includes a forwarding module 2306 for, responsive to said determining, forwarding the message to the UE. It will be appreciated that all of the variants discussed above for the method shown in Figure 12, for example, are applicable to the functional implementation shown in Figure 23.
  • Figure 24 illustrates an example functional module or circuit architecture for a network node 30 that is operating as a donor node according to various ones of the embodiments described herein.
  • the functional implementation includes a preparing module 2402 for preparing a message for conditional delivery by the first relay node to the UE, the message including or being associated with one or more triggering conditions.
  • the functional implementation further comprises a sending module 2404 for sending the message to the first relay node, the message including or being associated with an indication that the message is not to be delivered until at least one of the one or more triggering conditions is fulfilled. It will be appreciated that all of the variants discussed above for the method shown in Figure 13, for example, are applicable to the functional implementation shown in Figure 24.
  • Figure 25 illustrates an example functional module or circuit architecture for a UE 50 that is operating as a donor node according to various ones of the embodiments described herein.
  • the functional implementation includes a receiving module 2502 for receiving, from a relay node serving the UE and relaying communications between the UE and a core network, via a donor network node, a conditional reconfiguration message, the conditional reconfiguration message comprising at least one reconfiguration message associated with a corresponding target network node.
  • the functional implementation further comprises a cell selection module 2504 for performing cell selection, responsive to fulfilment of a trigger event.
  • the functional implementation further includes a handover module 2506 for performing a conditional handover according to the reconfiguration message associated with the target network node, responsive to selecting a cell corresponding to the target network node. It will be appreciated that all of the variants discussed above for the method shown in Figure 16, for example, are applicable to the functional implementation shown in Figure 25.
  • Figure 26 illustrates an example functional module or circuit architecture for a UE 50 that is operating as a donor node according to various ones of the embodiments described herein.
  • the functional implementation includes a receiving module 2602 for receiving, from a relay node serving the UE and relaying communications between the UE and a core network, via a donor network node, a conditional release message, the conditional release message including or being associated with one or more triggering conditions.
  • the functional implementation further comprises a determining module 2604 for determining that at least one of the one or more triggering conditions is fulfilled.
  • the functional implementation further includes a releasing module 2606 for, responsive to said determining, releasing the UE’s connection to the relay node according to the conditional release message.
  • EE2 The method of example embodiment EE 1, wherein the message is a release message instructing the UE to release its current radio connection.
  • EE 3 The method of example embodiment EE 1 or EE 2, wherein the message comprises redirection information directing the UE to select a cell at a given frequency.
  • EE 4 The method of any one of example embodiments EE1- EE3, wherein the relay node is an integrated access backhaul, IAB, network node serving as an access IAB node for the UE, and wherein the donor network node is operating as a donor central unit, CU.
  • the relay node is an integrated access backhaul, IAB, network node serving as an access IAB node for the UE, and wherein the donor network node is operating as a donor central unit, CU.
  • EE5 The method of any one of example embodiments EE1-EE4, wherein the method further comprises releasing a UE context for the UE, at the relay node, upon or after forwarding the message to the UE.
  • EE6 The method of any one of example embodiments EE1-EE5, wherein the message includes or is associated with a timer value, the method further comprising starting a timer, wherein said determining that at least one of the triggering conditions is fulfilled comprises determining that the timer has expired.
  • EE7 The method of example embodiment EE6, wherein the method comprises either: starting the timer upon receiving the message; or starting the timer upon fulfillment of an intermediate condition included in or associated with the message.
  • EE8 The method of any one of example embodiments EE1-EE7, wherein at least one of the one or more triggering conditions is predefined in the relay node, prior to receiving the message. EE9. The method of any one of example embodiments EE1-EE8, wherein the method further comprises receiving an indication of at least one of the one or more triggering conditions from the donor network node upon or after connection of the UE to the relay node, prior to receiving the message.
  • EE 10 The method of any one of example embodiments EE1-EE9, wherein the one or more triggering conditions includes one or more of any one or more of the following: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; a failure to recover a backhaul link toward a parent node after detecting a failure on the backhaul link.
  • EE13 The method of example embodiment EE 12, wherein the message is a release message instructing the UE to release its current radio connection.
  • EE 16 The method of any one of example embodiments EE12-EE14, wherein preparing the message comprises determining that the EfE does support an RRC INACTIVE state and including a suspend configuration indication in the message in response to said determining.
  • preparing the message further comprises at least one of the following: assigning to the UE at least one Inactive State Radio Network Temporary Identifier, I- RNTI, for use by the UE when resuming a connection after receiving the message from the relay node; providing to the UE a next hop chaining counter (NCC); and including redirection information in the message.
  • I- RNTI Inactive State Radio Network Temporary Identifier
  • EE18 The method of any one of example embodiments EE12-EE17, wherein the message includes or is associated with a timer value for use by the relay node for starting a timer, where expiration of the timer at the relay node is one of the one or more trigger conditions.
  • EE19 The method of any one of example embodiments EE12-EE18, wherein at least one of the one or more triggering conditions is predefined in the relay node, prior to the sending of the message to the relay node.
  • EE20 The method of any one of example embodiments EE12-EE19, wherein the method further comprises sending an indication of at least one of the one or more triggering conditions to the relay node upon or after connection of the UE to the relay node, prior to sending the message.
  • EE21 The method of any one of example embodiments EE12-EE18, wherein at least one of the one or more triggering conditions is predefined in the relay node, prior to the sending of the message to the relay node.
  • any one of example embodiments EE12-EE20 wherein the one or more triggering conditions includes one or more of any one or more of the following: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; a failure to recover a backhaul link toward a parent node after failure of the backhaul link.
  • EE22 The method of any one of example embodiments EE12-EE21, further comprising: sending an update message to the relay node, the update message indicating a change in one or more trigger conditions and/or indicating one or more additional trigger conditions.
  • EE23 The method of any one of example embodiments EE12-EE22, further comprising: receiving a context retrieve request for the EfE from another network node, after sending the message; sending a EfE context for the EfE to the another network node; and releasing the EfE context for the EfE and associated resources.
  • EE24 The method of any one of example embodiments EE12-EE21, further comprising: sending an update message to the relay node, the update message indicating a change in one or more trigger conditions and/or indicating one or more additional trigger conditions.
  • a method, in a user equipment, EfE comprising: receiving, from a relay node serving the EfE and relaying communications between the EfE and a core network, via a donor network node, a conditional release message, the conditional release message including or being associated with one or more triggering conditions; determining that at least one of the one or more triggering conditions is fulfilled; and, responsive to said determining, releasing the EfE’s connection to the relay node according to the conditional release message.
  • the triggering condition is the receipt of an indication from the relay node indicating that the conditional release message is to be executed.
  • conditional release message comprises redirection information directing the EfE to select a cell at a given frequency.
  • EE27 One or more network nodes or base stations adapted to perform the methods of any of example embodiments EE1-EE23.
  • a network node or base station comprising transceiver circuitry and processing circuitry operatively associated with the transceiver circuitry and configured to perform the methods of any of example embodiments EE1-EE23.
  • a computer program comprising instructions that, when executed on at least one processing circuit of a network node or base station, cause the at least one processing circuit to carry out the method according to any one of example embodiments EE1-EE23.
  • EE31 A user equipment, LIE, adapted to perform a method according to any of example embodiments EE24-EE26.
  • a user equipment, LIE, comprising transceiver circuitry and processing circuitry operatively associated with the transceiver circuitry and configured to perform the methods of any of example embodiments EE24-EE26.
  • EE33 A computer program comprising instructions that, when executed on at least one processing circuit of a user equipment, EfE, cause the at least one processing circuit to carry out the method according to any one of example embodiments EE24-EE26.
  • EE34 A carrier containing the computer program of example embodiment EE33, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.
  • a communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network comprises a base station having a radio interface and processing circuitry, the base station’s processing circuitry configured to perform any of the operations comprising embodiments EE 1-EE23.
  • UE user equipment
  • the communication system of the previous embodiment further including the base station.
  • the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the EfE’s processing circuitry is further configured to execute a client application associated with the host application.
  • a communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a User equipment (UE) to a base station, the base station comprising a radio interface and processing circuitry configured to communicate with the base station and cooperatively perform operations of any of embodiments EE1-EE23.
  • UE User equipment
  • the communication system of the previous embodiment further including the base station.
  • EE44 The method of example embodiment EE43, wherein the relay node is an integrated access backhaul, IAB, network node serving as an access IAB node for the EE, and wherein the donor network node is operating as a donor central unit, CU.
  • EE45 The method of example embodiment EE43 or EE44, wherein the method comprises receiving a plurality of connection reconfiguration messages for the EE, including the first connection reconfiguration message, and wherein the method further comprises selecting the first connection reconfiguration message, based on the at least one of the triggering conditions being filled, for forwarding to the UE.
  • EE46 The method of any one of example embodiments EE43EE45, wherein the first connection reconfiguration message includes or is associated with a timer value, the method further comprising starting a timer, wherein said determining that at least one of the triggering conditions is fulfilled comprises determining that the timer has expired.
  • EE47 The method of example embodiment EE46, wherein the method comprises either: starting the timer upon receiving the first connection reconfiguration message; or starting the timer upon fulfillment of an intermediate condition included in or associated with the first connection reconfiguration message.
  • EE48 The method of any one of example embodiments EE43-EE47, wherein at least one of the one or more triggering conditions is predefined in the relay node, prior to receiving the first connection reconfiguration message.
  • EE49 The method of any one of example embodiments, EE43-EE48, wherein the method further comprises receiving an indication of at least one of the one or more triggering conditions from the donor network node upon or after connection of the EfE to the relay node, prior to receiving the first connection reconfiguration message. EE50.
  • any one of example embodiments EE43-EE49 wherein the one or more triggering conditions includes one or more of any one or more of the following: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; a failure to recover a backhaul link toward a parent node after detecting a failure on the backhaul link.
  • the one or more triggering conditions includes one or more of any one or more of the following: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; a failure to recover a backhaul link toward a parent node after detecting a failure on the backhaul link.
  • any one of example embodiments EE43-EE50 further comprising: receiving an update message from the donor network node, the update message indicating a change in one or more trigger conditions and/or indicating one or more additional trigger conditions; and updating the one or more trigger conditions in accordance with the update message; wherein determining that at least one of the triggering conditions is fulfilled comprises determining that at least one of the triggering conditions as updated by the update message is fulfilled.
  • a method in a donor network node serving a user equipment, UE, via at least a first relay node relaying communications between the LIE and the donor network node, the method comprising: preparing a first connection reconfiguration message for conditional delivery by the first relay node to the EfE, the first connection reconfiguration message including or being associated with one or more triggering conditions; sending the first reconfiguration message to the first relay node, the first connection reconfiguration message including or being associated with an indication that the message is not to be delivered until at least one of the one or more triggering conditions is fulfilled.
  • EE53 The method of example embodiment EE52, wherein the relay node is an integrated access backhaul, IAB, network node serving as an access IAB node for the EfE, and wherein the donor network node is operating as a donor central unit, CEf.
  • IAB integrated access backhaul
  • CEf donor central unit
  • EE54 The method of example embodiment EE52 or EE53, wherein the message includes or is associated with a timer value for use by the relay node for starting a timer, where expiration of the timer at the relay node is one of the one or more trigger conditions.
  • EE55 The method of any one of example embodiments EE52-EE54, wherein at least one of the one or more triggering conditions is predefined in the relay node, prior to the sending of the message to the relay node.
  • EE56 The method of any one of example embodiments EE52-EE55, wherein the method further comprises sending an indication of at least one of the one or more triggering conditions to the relay node upon or after connection of the EfE to the relay node, prior to sending the message.
  • EE57 The method of any one of example embodiments EE52-EE56, wherein the one or more triggering conditions includes one or more of any one or more of the following: detection of a backhaul link failure at the relay node on a connection toward a parent node; detection of a signal quality drop on a backhaul link toward a parent node; detection of congestion exceeding a predetermined threshold on a backhaul link toward a parent node; a failure to recover a backhaul link toward a parent node after failure of the backhaul link.
  • EE58 The method of any one of example embodiments EE52-EE57, further comprising: sending an update message to the relay node, the update message indicating a change in one or more trigger conditions and/or indicating one or more additional trigger conditions.
  • EE59 The method of any of example embodiments EE52-EE58, the method further comprising: transmitting, to a candidate target network node, a handover request for the LIE, the handover request including an indication that the handover request is for conditional handover; and receiving an acknowledgement message from the candidate target network node, in response to the handover, the acknowledgement message including a conditional handover reconfiguration message; wherein the first connection reconfiguration message is the conditional handover reconfiguration message.
  • EE60 The method of example embodiment EE59, the method further comprising: receiving a measurement report from the LIE and/or load information for each of one or more network nodes; sending a message to the relay node indicating the first connection reconfiguration message from a plurality of connection reconfiguration messages for the LIE sent to the LIE, in response to the measurement report from the LIE and/or the load information.
  • conditional reconfiguration message includes or is associated with one or more triggering conditions, the one or more triggering conditions specifying conditions upon which the UE is to start applying the conditional reconfiguration message.
  • a method, in a user equipment, UE comprising: receiving, from a relay node serving the UE and relaying communications between the UE and a core network, via a donor network node, a conditional reconfiguration message, the conditional reconfiguration message comprising at least one reconfiguration message associated with a corresponding target network node; responsive to fulfilment of a trigger event, performing cell selection; and, responsive to selecting a cell corresponding to the target network node, performing a conditional handover according to the reconfiguration message associated with the target network node.
  • EE66 The method of example embodiment EE65, wherein the trigger event is radio link failure with the relay node.
  • EE67 The method of example embodiment EE65, wherein the trigger event is receipt of an indication indicating to the UE that the UE is to start applying the conditional reconfiguration message.
  • EE68 The method of example embodiment EE67, wherein the indication identifies the target network node or a cell associated with the target network node.
  • EE69 The method of any of example embodiments EE65-EE68, wherein the reconfiguration message includes or is associated with one or more trigger conditions, and wherein performing the conditional handover according to the reconfiguration message is further conditioned on at least one of the one or more trigger conditions being met.
  • EE70 One or more network nodes or base stations adapted to perform the methods of any of example embodiments EE43-EE64.
  • a network node or base station comprising transceiver circuitry and processing circuitry operatively associated with the transceiver circuitry and configured to perform the methods of any of example embodiments EE43-EE64.
  • EE72 A computer program comprising instructions that, when executed on at least one processing circuit of a network node or base station, cause the at least one processing circuit to carry out the method according to any one of example embodiments EE43-EE64.
  • EE73 A carrier containing the computer program of example embodiment EE72, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.
  • a user equipment, LIE adapted to perform a method according to any of example embodiments EE65-EE69.
  • EE75 A user equipment, LIE, comprising transceiver circuitry and processing circuitry operatively associated with the transceiver circuitry and configured to perform the methods of any of example embodiments EE65-EE69.
  • EE76 A computer program comprising instructions that, when executed on at least one processing circuit of a user equipment, EfE, cause the at least one processing circuit to carry out the method according to any one of example embodiments EE65-EE69.
  • EE77 A carrier containing the computer program of example embodiment EE76, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.
  • a communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network comprises a base station having a radio interface and processing circuitry, the base station’s processing circuitry configured to perform any of the operations comprising embodiments EE43-EE64.
  • UE user equipment
  • the communication system of the previous embodiment further including the base station.
  • the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the EfE’s processing circuitry is further configured to execute a client application associated with the host application.
  • a communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a User equipment (UE) to a base station, the base station comprising a radio interface and processing circuitry configured to communicate with the base station and cooperatively perform operations of any of embodiments EE43-EE64.
  • UE User equipment
  • the communication system of the previous embodiment further including the base station.
  • FWA fixed wireless access gNB Base station supporting NR air interface gNB-CU Same as CU gNB-CU-CP CU- control plane gNB-CU-UP CU- User plane gNB -DU same as DU
  • IPsec IP Security I-RNTI RNTI used in Inactive state FTE Fong Term Evolution MAC Medium Access Control MAC CE MAC Control Element
  • TX T ransmit/T ransmitter UDP User Datagram Protocol UE User Equipment UL Uplink UP User plane
  • UPF User Plane Function Uu Interface between MT and gNB X2 Interface between base stations (EUTRA-EUTRA or EUTRA-NR)

Landscapes

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

Abstract

Un procédé donné à titre d'exemple, dans un nœud de relais desservant un équipement utilisateur, UE, et relayant des communications entre l'UE et un réseau central, par l'intermédiaire d'un nœud de réseau donneur, comprend une étape consistant à recevoir (1210), en provenance du nœud de réseau donneur, un message pour une distribution conditionnelle à l'UE, le message comprenant ou étant associé à une ou plusieurs conditions de déclenchement. Le procédé consiste en outre à déterminer (1220) qu'au moins une des conditions de déclenchement est remplie, et, en réponse à ladite détermination, à transmettre (1230) le message à l'UE.
PCT/SE2021/050314 2020-04-24 2021-04-07 Procédés et nœuds dans des réseaux de liaison terrestre à accès intégré WO2021215979A1 (fr)

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