CN112715053A

CN112715053A - System, apparatus and method for handling radio link monitoring and radio link failure in a wireless relay network

Info

Publication number: CN112715053A
Application number: CN201980057833.2A
Authority: CN
Inventors: 生嘉; 约翰·M·科沃斯基; 相羽立志; 横枕一成
Original assignee: Sharp Corp
Current assignee: FG Innovation Co Ltd; Sharp Corp
Priority date: 2018-09-27
Filing date: 2019-09-27
Publication date: 2021-04-27
Also published as: EP3858092A1; WO2020067517A1

Abstract

A node is disclosed that includes monitoring circuitry configured to monitor radio link conditions on one or more portions of Bandwidth (BWPs) of a parent node and detection circuitry configured to detect Radio Link Failure (RLF) in at least one downlink BWP.

Description

System, apparatus and method for handling radio link monitoring and radio link failure in a wireless relay network

Technical Field

Embodiments of the present invention relate to integrating access and backhaul for New Radio (NR) networks with next generation NodeB capability and signaling. In particular, embodiments of the present invention relate to backhaul infrastructure and design for user equipment and relay networks to handle radio link failures.

Background

In typical cellular mobile communication systems and networks, such as Long Term Evolution (LTE) and New Radio (NR), the service area is covered by one or more base stations, where each of such base stations may be connected to the core network by a fixed line backhaul link (e.g., fiber optic cable). In some cases, users tend to encounter performance problems due to weak signals from base stations at the edge of the service area, such as: reduced data rate, high probability of link failure, etc. The relay node concept has been introduced to extend the coverage area and improve signal quality. As implemented, the relay node may connect to the base station using a wireless backhaul link.

In the 3 rd generation partnership project (3GPP), a relay node concept for fifth generation (5G) cellular systems has been discussed and standardized, wherein the relay node can utilize the same 5G radio access technology (new radio (NR)) for simultaneous operation of providing service (access link) to User Equipment (UE) and connection to the core network (backhaul link). These radio links may be multiplexed in time, frequency, and/or space. The system may be referred to as Integrated Access and Backhaul (IAB).

Some such cellular mobile communication systems and networks may include an IAB carrier and an IAB node, wherein the IAB carrier may provide an interface to the UE to connect to the core network and provide wireless backhaul functionality to the IAB node; and, in addition, IAB nodes may support wireless access to UEs and wireless backhaul of access traffic. An IAB node may need to periodically perform inter-IAB node discovery to detect new IAB nodes in its vicinity based on a cell-specific reference signal (e.g., a single sideband SSB). Cell-specific reference signals may be broadcast on a Physical Broadcast Channel (PBCH), where packets may be carried or broadcast on a Master Information Block (MIB) segment.

The demand for wireless traffic increases significantly over time and the IAB system is expected to be able to reliably and robustly handle a variety of possible failures. These factors have been considered for IAB backhaul design. In particular, methods and programs are provided that address radio link failures on backhaul links.

Disclosure of Invention

In one example, there is provided a method of handling radio link monitoring and Radio Link Failure (RLF) in a wireless relay network having a carrier node, a first parent node (IAB node a), a second parent node (IAB node B), and a child node (IAB node/UE), wherein the carrier node is an Integrated Access and Backhaul (IAB) node connected to a core network, the method comprising: monitoring, by the child node, radio link conditions on one or more bandwidth portions (BWPs) of the parent node; detecting, by the child node, a potential RLF in at least one active Downlink (DL) BWP; determining, by the child node, an RLF or potential RLF based on the monitored BWP of the parent node; and configuring, by the network, an active BWP handover to maintain an IAB parent backhaul radio link in active BWP based on the radio link conditions.

Drawings

Various embodiments of the present invention will now be discussed in detail, with emphasis on the advantageous features. These embodiments depict novel and non-obvious aspects of the present invention, which are shown in the drawings, which are for illustrative purposes only. These drawings include the following figures, in which like numerals represent like parts.

Fig. 1 shows a mobile network infrastructure using 5G signals and 5G base stations.

Fig. 2 depicts an example of a functional block diagram of an IAB bearer and an IAB node.

Fig. 3 illustrates control plane (C-plane) and user plane (U-plane) protocols between a UE, an IAB node and an IAB bearer.

Fig. 4 depicts a functional block diagram of an exemplary protocol stack configuration of the U-plane.

Fig. 5A depicts a functional block diagram of an exemplary protocol stack configuration of the C-plane between IAB nodes connected to an IAB carrier.

Fig. 5B depicts a functional block diagram of an exemplary C-plane protocol stack configuration of an IAB node that is connected to another IAB node that is connected to an IAB carrier.

Fig. 5C depicts a functional block diagram of an exemplary C-plane protocol stack configuration for RRC signaling of a UE.

Fig. 6A depicts an exemplary message sequence for an IAB node to establish an RRC connection followed by an F1-AP connection.

Fig. 6B depicts an exemplary message sequence for an IAB node establishing an RRC connection with an IAB bearer, followed by an F1 setup procedure.

Fig. 7 shows an exemplary illustration of a scenario in which an IAB node detects a Radio Link Failure (RLF) on the upstream link to its parent node.

Fig. 8 illustrates an exemplary flow of information transmission/reception and/or processing to handle notification of RLF by a UE and/or an IAB node connected to a set of IAB nodes in communication with an IAB bearer.

Fig. 9A illustrates an exemplary flow of information transmission/reception and/or processing by a UE and/or an IAB node connected to a set of IAB nodes in communication with an IAB bearer based on receiving an upstream RLF notification.

Fig. 9B illustrates another exemplary flow for information transmission/reception and/or processing by a UE and/or an IAB node connected to a set of IAB nodes in communication with an IAB bearer based on not having received an upstream RLF notification.

Fig. 10A illustrates an exemplary scenario of an upstream potential RLF notification that a threshold has been reached based on a higher layer on the IAB node having determined multiple "out of sync" indications from a lower layer.

Fig. 10B illustrates another exemplary scenario in which a parent node detects a certain number of consecutive "out of sync" indications and starts a timer T2.

Fig. 10C illustrates another exemplary scenario of an upstream potential RLF notification, where the notification is based on a higher layer on the IAB node having determined that multiple PRACH preamble transmission attempts failed.

Fig. 10D illustrates another exemplary scenario for upstream potential RLF notification based on a higher layer on the IAB node having determined that multiple RLC layer data transfer attempts have failed.

Fig. 10E depicts an exemplary message sequence for a parent IAB node to communicate with another parent IAB node and a UE/IAB child node to handle an upstream potential RLF notification.

Fig. 10F depicts an exemplary message sequence for a parent IAB node to communicate with a set of other parent IAB nodes and UE/IAB child nodes to handle an upstream potential RLF notification.

Fig. 11 shows an example of a set of components of a user equipment or a base station.

Fig. 12 illustrates a mobile network infrastructure in which multiple UEs are connected to a set of IAB nodes, and the IAB nodes communicate with each other and/or with an IAB bearer.

FIG. 13 illustrates an exemplary top-level functional block diagram of a computing device embodiment.

Fig. 14 is a flow diagram depicting an example process for handling RLF in an example of a wireless relay network.

Fig. 15A is a functional block diagram of a wireless node device, which may be a parent IAB node that may communicate with an upstream IAB carrier and downstream UEs and/or child IAB nodes.

Fig. 15B is a functional block diagram of a wireless end device, which may be an IAB node communicating with an IAB carrier or upstream parent IAB node.

Fig. 16 is a diagram illustrating an example of a radio protocol architecture for the control plane and the user plane in a mobile communication network.

Detailed Description

Various embodiments of the present systems, devices and methods for handling radio link monitoring and radio link failure in a wireless relay network have several features, individual ones of which cannot be solely responsible for their desirable attributes. Without limiting the scope of the embodiments of the invention expressed by the appended claims, their more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "detailed description of certain embodiments" one will understand how the features of embodiments of this invention provide the advantages described herein.

The disclosed embodiments provide methods and systems for handling scenarios in which an Integrated Access and Backhaul (IAB) node (e.g., an IAB parent node and/or an IAB child node) disconnects or may disconnect from a network due to a radio link failure or a potential radio link failure. The disclosed embodiments provide a method for an IAB node (e.g., an IAB parent) to monitor radio link conditions on one or more bandwidth portions (BWPs) of a serving cell. When a radio link failure has occurred or is likely to occur in at least one active Downlink (DL) BWP, the network configures the active BWP handover to maintain good radio conditions for the IAB parent backhaul radio link in the active BWP.

Various embodiments of the present systems, devices and methods for handling radio link monitoring and radio link failure in a wireless relay network will now be discussed in detail, highlighting the advantageous features. In addition, the following detailed description describes embodiments of the invention with reference to the accompanying drawings.

A source and a destination in a mobile network used in a wireless network may be interconnected by a plurality of nodes. In such networks, the source and destination may not be able to communicate directly with each other, since the distance between the source and destination is greater than the transmission range of the node. That is, intermediate nodes are required to relay communications and provide information transfer. Thus, intermediate nodes may be used to relay information signals in a relay network having a network topology in which sources and destinations are interconnected by such intermediate nodes. In a hierarchical telecommunications network, the backhaul portion of the network may include intermediate links between the core network and small sub-networks of the entire hierarchical network. Integrated Access and Backhaul (IAB) next generation nodebs use 5G new radio communications such as the transmission and reception of NR user plane (U-plane) data traffic and NR control plane (C-plane) data. Both the UE and the gNB may include addressable memory in electronic communication with the processor. In one embodiment, the instructions may be stored in a memory and executable to process received packets and/or transmit packets according to different protocols (e.g., a Medium Access Control (MAC) protocol and/or a Radio Link Control (RLC) protocol).

In some aspects of embodiments for handling radio link failure in a wireless relay network, Mobile Terminal (MT) functionality is disclosed that is typically provided by a User Equipment (UE) terminal, which may be implemented by a base station (BTS or BS) node (e.g., IAB node). In one embodiment, the MT functionality may include common functions such as: radio transmission and reception, encoding and decoding, error detection and correction, signaling, and access to the SIM.

In mobile networks, an IAB child node may establish a connection with an IAB node/bearer or parent using the same initial access procedure (discovery) as accessing a UE, attaching to the network or camping on a cell. In one embodiment, a Radio Resource Control (RRC) protocol may be used to signal between the 5G radio network and the UE, where the RRC may have at least two states (e.g., RRC _ IDLE and RRC _ CONNECTED) and state transitions. The RRC sublayer may enable connection establishment based on broadcasted system information and may also include security procedures. The U-plane may include PHY, MAC, RLC, and PDCP layers.

Embodiments of the present system disclose methods and apparatus for an IAB node to notify a child node and/or UE of upstream radio conditions, and thus the term "IAB node" may be used to refer to either a parent IAB node or a child IAB node, depending on the location of the IAB node in network communications with an IAB bearer responsible for physical connection with a core network. Embodiments are disclosed in which an IAB node (a child IAB node) may follow the same initial access procedures as a UE, including cell search, system information acquisition, and random access, in order to initially establish a connection with a parent IAB node or an IAB bearer. That is, when an IAB base station (eNB/gNB) needs to establish a backhaul connection to or camp on a parent IAB node or IAB carrier, the IAB node may perform the same processes and steps as a UE, wherein the IAB node may be considered a UE, but the parent IAB node or IAB carrier distinguishes the IAB node from the UE.

In the disclosed embodiments for handling radio link failure in a wireless relay network, the MT functionality typically provided by the UE may be implemented on the IAB node. In some examples of the disclosed system, method, and device embodiments, it may be considered to have an IAB node monitor radio conditions on a radio link to a parent IAB node, where the parent IAB node may itself be a child IAB node in communication with an IAB carrier.

Referring to fig. 1, the present embodiment includes a mobile network infrastructure using 5G signals and 5G base stations (or cell sites). A system diagram of a radio access network utilizing IAB nodes is depicted, wherein the radio access network may include, for example, one IAB bearer and a plurality of IAB nodes. Different embodiments may include different numbers of IAB carrier to IAB node ratios. The IAB node may be referred to herein as an IAB relay node. The IAB node may be a Radio Access Network (RAN) node that supports wireless backhaul for wireless access and access traffic to the UE. The IAB bearer is a RAN node that may provide the UE with an interface to a connected core network and provide wireless backhaul functionality to the IAB node. An IAB node/bearer may serve one or more IAB nodes using a wireless backhaul link and simultaneously serve a UE using a wireless access link. Thus, the network backhaul traffic state may be implemented based on a wireless communication system connected to multiple IAB nodes and UEs.

With further reference to fig. 1, a plurality of UEs are depicted in communication with IAB nodes (e.g., IAB nodes and IAB carrier nodes) via radio access links. In addition, an IAB node (child node) may communicate with other IAB nodes and/or IAB bearers (all of which may be considered IAB parent nodes) via wireless backhaul links. For example, a UE may connect to an IAB node, which itself may connect to a parent IAB node in communication with an IAB bearer, thereby extending backhaul resources to allow backhaul traffic to be transported within the network and between parents and children for integrated access. Embodiments of the system provide the capability needed to carry information bits using a broadcast channel (on a physical channel) and provide access to the core network.

Fig. 2 shows an example of a functional block diagram of an IAB bearer and an IAB node (see fig. 1). The IAB carrier may include at least one Centralized Unit (CU) and at least one Distributed Unit (DU). A CU is a logical entity that manages the collocation of DUs in an IAB bearer and remote DUs residing in an IAB node. A CU may also be an interface to a core network, appearing as a RAN base station (e.g., eNB or gNB). In some embodiments, the DU is a logical entity that hosts the radio interface (backhaul/access) for other child IAB nodes and/or UEs. In one configuration, under control of a CU, a DU may provide physical layer and layer 2(L2) protocols (e.g., Medium Access Control (MAC), Radio Link Control (RLC), etc.), while the CU may manage upper layer protocols such as Packet Data Convergence Protocol (PDCP), Radio Resource Control (RRC), etc. The IAB node may include DU and Mobile Terminal (MT) functionality, where in some embodiments the DU may have the same functionality as the DU in the IAB bearer, while the MT may be a UE-like functionality that terminates the radio interface layer. For example, the MT may be used to perform at least one of the following: radio transmission and reception, encoding and decoding, error detection and correction, signaling, and access to the SIM.

Embodiments include a mobile network infrastructure in which multiple UEs are connected to a set of IAB nodes, and the IAB nodes communicate with each other to relay and/or communicate with an IAB carrier using various aspects of embodiments of the invention. In some embodiments, the UE may communicate with the CUs of the IAB bearer on the C-plane using the RRC protocol; and in other embodiments, the UE may use a Service Data Adaptation Protocol (SDAP) and/or Packet Data Convergence Protocol (PDCP) radio protocol architecture for data transmission (U-plane) over the NR gbb. In some embodiments, the IAB node's DUs may use the 5G radio network layer signaling protocol: f1 communicates with CUs of the IAB bearer using a protocol (F1-AP), which is a wireless backhaul protocol that provides signaling services between DUs of the IAB nodes and CUs of the IAB bearer. That is, as described further below, the protocol stack configurations may be interchangeable and different mechanisms may be used.

As shown in the diagram shown in fig. 3, the protocols between the UE, the IAB node and the IAB bearer are grouped into a control plane (C-plane) and a user plane (U-plane). The C-plane carries control signals (signaling data) and the U-plane carries user data. Fig. 3 shows an example of an embodiment where there are two IAB nodes, i.e. IAB node 1 and IAB node 2 (two hops) between the UE and the IAB bearer. Other embodiments may include networks with a single hop or multiple hops, where there may be more than two IAB nodes.

Fig. 4 depicts a functional block diagram of an exemplary protocol stack configuration of the U-plane, which includes a service data protocol (e.g., SDAP, 3GPP TS 38.324) that can carry user data (e.g., via IP packets). In one embodiment, the SDAP runs on top of the PDCP (3GPP TS 38.323) and L2/physical layers. In one embodiment, an adaptation layer is introduced between the IAB node and the IAB node/bearer, where the adaptation layer carries relay-specific information such as IAB node/bearer address, QoS information, UE identifier and potentially other information. In this embodiment, the RLC (3GPP TS 38.322) may provide reliable transmission in a hop-by-hop manner, while the PDCP may perform end-to-end (UE-CU) error recovery. A GTP-U (GPRS tunneling protocol user plane) may be used to route user data between CUs and DUs within the IAB bearer.

Fig. 5A is a functional block diagram of an exemplary protocol stack configuration of the C-plane between an IAB node (IAB node 1) directly connected to an IAB carrier (via a single hop). In this embodiment, the MT component of the IAB node 1 may establish an RRC connection with the CU component of the IAB bearer. In parallel, RRC can be used to carry another signaling protocol for the CU/IAB bearer to control the DU components residing in IAB node 1. In one embodiment, such signaling protocol may be referred to as F1 application protocol (F1-AP), which is a protocol based on F1-AP specified in 3GPP TS 38.473 and described above, with potential extension features to accommodate wireless backhaul (original F1-AP was designed for wireline). In other embodiments, F1-AP may be used for CU-DU connections inside the IAB carrier. Assume that under RLC, the MAC/PHY layer is shared with the U-plane.

Fig. 5B depicts a functional block diagram of an exemplary C-plane protocol stack configuration of IAB node 2, which is connected to IAB node 1(2 hops) as previously described. In one embodiment, it may be assumed that IAB node 1 has established an RRC/F1-AP connection with the IAB bearer, as shown in fig. 5A. In IAB node 1, the signaling bearers for RRC/PDCP for IAB node 2 may be carried by the adaptation layer to the IAB bearer. Similar to fig. 5A, F1-AP signaling is carried by the RRC of the IAB node 2.

Fig. 5C depicts yet another functional block diagram of an exemplary C-plane protocol stack configuration for RRC signaling for a UE in the 2-hop relay configuration shown in fig. 5B. Thus, a UE with MT features and functionality can connect to a CU of an IAB carrier via the C-plane. As shown, although traffic is routed through IAB node 2 and IAB node 1, these two nodes are passive nodes because data is passed to the next node without manipulation. That is, the UE transmits data to a node connected to, for example, IAB node 2, then IAB node 2 transmits data to a node connected to, for example, IAB node 1, and then IAB node 1 transmits (without steering) the data to the IAB bearer.

Fig. 5A, 5B and 5C show that each IAB node or UE MT has its own end-to-end RRC connection with the CU of the IAB bearer. Likewise, the DU of each IAB node has an end-to-end F1-AP connection with the CU of the IAB carrier. Any IAB node that exists between such endpoints transparently passes RRC or F1-AP signaling traffic.

Fig. 6A and 6B are illustrations of exemplary flows of information transmission/reception and/or processing by an IAB node and an IAB bearer in accordance with aspects of an embodiment of the present invention.

Fig. 6A depicts an exemplary message sequence for IAB node 1 to establish an RRC connection followed by an F1-AP connection. Assume that the IAB node 1 has been preconfigured (or configured by the network) with information indicating how to select the cell served by the IAB bearer. As shown, the IAB node 1 in IDLE state (RRC IDLE) may initiate the RRC connection establishment procedure by sending a random access preamble to the IAB bearer, which may be received and processed by the DU of the IAB bearer. Upon successful reception of the random access response from the IAB bearer, IAB node 1 may send a RRCSetupRequest, then receive a RRCSetup and transmit a RRCSetupComplete. At this point in the message sequence, the IAB node 1 may enter a CONNECTED state (RRC _ CONNECTED) with the IAB bearer and may proceed with the security procedures to configure the ciphering/integrity protection features. The CU of the IAB bearer may also send rrcreeconfiguration, which may include configuration parameters for configuring radio bearers, such as Data Radio Bearers (DRBs) and Signaling Radio Bearers (SRBs), to the IAB node 1. In some embodiments, RRCReconfiguration is sent to modify the RRC connection and establish a radio connection between the UE and the network, however, in this embodiment rrccofiguration may also be sent to configure the connection between the IAB node and the network. The RRC connection reconfiguration message may be used, for example, to establish/modify/tear down radio bearers and/or perform handovers and the like. In one embodiment, any RRC message transmitted from IAB node 1 may include information identifying IAB node 1 as an IAB node (rather than a UE). For example, the bearer CU may be configured with a list of node identities (e.g., IMSI or S-TMSI) that are allowed to use the service from the bearer. This information may be used by the CUs in the sub-sequence operation, e.g., to distinguish the UE from the IAB node.

As described above, after the RRC connection establishment procedure, the IAB node 1 and the DU of the IAB bearer may proceed with the F1 setup procedure using the F1-AP protocol, which may activate one or more cells served by the DU of the IAB node 1, thereby allowing other IAB nodes and/or UEs to camp on the cells. In this process, the adaptation layers of the IAB node 1 and the IAB bearer may also be configured and activated.

Fig. 6B depicts an exemplary message sequence or information flow for IAB node 2 establishing an RRC connection with an IAB bearer, followed by the F1 setup procedure. In this embodiment, it is assumed that the IAB node 1 has performed the procedure disclosed in fig. 6A for establishing RRC and F1-AP connections. Referring back to fig. 3, IAB node 2, which is shown communicating with IAB node 1 via a radio interface, may also be depicted in fig. 6B as a child node of IAB node 1, in accordance with an aspect of an embodiment of the present invention.

Due to the nature of wireless communications, wireless backhaul links are susceptible to degradation or disconnection over time. In aspects of embodiments of the present invention, the MT part of the IAB node may continuously monitor the quality of the radio link and/or the signal quality upstream of the IAB node, where the radio link may be connected to the parent IAB node/bearer of the IAB node. If the radio problem cannot be recovered for a specified duration, the MT may declare a Radio Link Failure (RLF), which means that a communication link loss may have occurred or that the signal strength is difficult to continue (e.g., below a threshold).

Fig. 7 shows an exemplary illustration of a scenario in which an IAB node (node a) detects RLF on an upstream link to its parent node (parent node 1). In some embodiments, the MT component of node a may need to find another parent node visible from the node. In this case, the MT component may perform a cell selection procedure, and if a suitable cell (parent node 2) is successfully found, node a may proceed with the RRC reestablishment procedure using the suitable cell (parent node 2). It should be noted that in this case, node a needs to find the cell served by the IAB node or the IAB bearer (i.e., a cell that does not support IAB is unsuitable). In one embodiment, a cell served by an IAB node or an IAB bearer may broadcast (e.g., in system information) a status as an indication indicating IAB capability, e.g., via a flag. Alternatively or in parallel, node a may be preconfigured or configured with a list of cell identities supporting IAB through the network.

The child IAB nodes (child node 1 and child node 2) and/or UEs (UE1 and UE2) may still be in connected mode with node a when node a attempts to find a new suitable IAB-capable serving cell. If node a successfully recovers from RLF before expiration of a preconfigured (or network configured) time period, the child node and/or UE may not be aware of RLF. However, in scenarios where node a fails to recover from RLF or fails to recover in a timely manner (e.g., before expiration of a preconfigured/network configured time period), not only may these child nodes/UEs suffer from service disruption, but all nodes/UEs in the downstream may also suffer from service disruption.

Embodiments of the present invention disclose systems, methods and apparatus in which an IAB node may inform connected nodes (children) or UEs of upstream radio conditions. In some embodiments, the upstream radio condition information may enable a child node or UE to decide whether to maintain a connection with an IAB node or to look for another node to connect with.

Fig. 8 illustrates an exemplary scenario of an upstream RLF notification that is detected upstream of a node and sent from the node (node a) to a child node and/or a directly connected UE. In one embodiment, upon receiving the notification, each of the child nodes and/or UEs may perform cell selection and, if successful, proceed with RRC reestablishment. As shown in fig. 8, after a successful selection to a new node (node B), each of the sub-nodes and/or UEs may begin a re-establishment procedure through the node B. That is, once a successful selection is made, the child node and/or UE may transmit a random access preamble/response message, and then a rrcreestablstringrequest and subsequent messages, as shown in fig. 8.

In one implementation, the upstream RLF notification may be carried by an adaptation layer (e.g., a header portion or a message body of an adaptation layer protocol). In alternative embodiments, or in addition, the notification may be carried by RLC sublayer, MAC, or physical layer signaling (e.g., PDCCH). In addition, the notification may be broadcast via system information or transmitted in a dedicated manner.

Thus, in one implementation, the RRC residing in each of the child nodes and/or UEs may perform cell selection upon receiving a notification indicating receipt of an upstream RLF notification from a lower layer. In the present embodiment, this operation can be performed even if the radio link connected to the parent node is kept in good condition. The node and/or UE may then start a timer Txxx (e.g., T311 specified in 3GPP TS 38.331) based on the received notification, and when the timer Txxx is running selecting a suitable cell, the node and/or UE may stop the timer Txxx and initiate transmission of a rrcreestablebluementrequest to the IAB bearer.

Once the RRC connection is re-established, the CU of the IAB bearer can update the F1-AP configuration in the node B and the child IAB node that initiated the RRC re-establishment. In the scenario where the connected devices are UEs, no F1-AP configuration update is needed because these devices do not have a F1-AP interface. Thus, the updated configuration from the IAB bearer can be used to reconfigure the routing topology that was modified or changed due to RLF.

Fig. 9A illustrates another scenario in which a child node and/or UE may start a timer, e.g., timer Tyyy, based on receiving an upstream RLF notification. While the timer Tyyy is running, node a may attempt to recover the upstream link by performing cell selection. In the scenario depicted in fig. 9, node a has successfully found a new parent node (parent node 2) and may initiate an RRC reestablishment procedure. Based on receiving F1-AP configuration update from the CU of the IAB carrier, node a may transmit/send an upstream resume notification to the child IAB node and/or the UE indicating that upstream is resumed. If the timer Tyyy has not expired, the child IAB node and/or UE receiving the notification may stop the timer Tyyy and remain connected with the node. If the timer expires before receiving the upstream recovery notification, the child IAB node and/or the UE may perform cell selection/RRC re-establishment, as shown in fig. 8. In one embodiment, the timer value/configuration may be preconfigured. In another embodiment, the timer value/configuration may be configured by a parent node (e.g., parent node 1) via dedicated signaling or via broadcast signaling (e.g., system information).

Similar to the previous scenario, in one implementation, the upstream RLF notification may be carried by adaptive layer, RLC, MAC, or physical layer signaling. In addition, the notification may be broadcast via system information or transmitted in a dedicated manner.

In yet another embodiment of the scenario, the RRC residing in each of the child nodes and/or UEs may start a timer Tyyy upon receiving an upstream RLF notification from the lower layer. If the node and/or UE receives a notification indicating that an upstream RLF notification is received from a lower layer while the timer Tyyy is running, the node and/or UE may stop the timer Tyyy. If the timer Tyyy expires, the node and/or UE may start the timer Txxx, and when a suitable cell is selected while the timer is running, the node and/or UE may stop the timer and initiate transmission of a rrcelestablishmentrequest.

Fig. 9B shows yet another scenario in which node a may start a timer Tzzz upon detection of RLF. In such a scenario, node a may or may not send the above-described upstream RLF notification to the child IAB node and/or the UE. While the timer Tzzz is running, node a may attempt to recover the upstream link by performing cell selection. In the scenario depicted in fig. 9B, at the expiration of the timer Tzzz (cell selection failure), node a may send a notification (e.g., an upstream disconnect notification) to the child IAB node/UE, notifying that RLF recovery was unsuccessful. In this case, the child IAB node/UE receiving the notification may start the timer Txxx described above and start a cell selection procedure, as shown in fig. 8. The notification may be carried in a broadcast or in a dedicated manner by the adaptation layer, RLC, MAC or physical layer signaling. In one embodiment, the timers Txxx and Tzzz may be the same timer or share the same configuration. In another embodiment, the timers Txxx and Tzzz may be different timers or different configurations.

In addition, the notification provided by the IAB node to its downstream (children/UEs) may not be limited to RLF or RLF recovery. In some embodiments, an IAB node may inform a child node and/or a UE of signal quality (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ)), error rates, and/or any other type of measurement result indicative of upstream radio conditions. In this case, the IAB node and/or UE may be preconfigured or configured by the network with conditions for initiating cell selection/re-establishment. The notification may be carried in a broadcast or in a dedicated manner by the adaptation layer, RLC, MAC or physical layer signaling.

In one embodiment, upon receiving one of the notifications from the parent node, the IAB node and/or the UE may send an acknowledgement or reply acknowledgement back to the parent node, as shown in fig. 8, 9A, and 9B.

In the above embodiments, whether a child IAB node or UE needs to find a new parent IAB node or wait for radio link recovery of the current parent IAB node may be based on when the parent node sends and/or transmits upstream RLF notifications and how to configure/trigger the associated timer. The following embodiments are directed to addressing and handling one or more situations or conditions that occur as a result of an RLF event.

With respect to RLF related procedures, in some embodiments, when in the RRC _ CONNECTED state, the UE and/or the child IAB node declares a Radio Link Failure (RLF) when one of the following criteria is met:

(A) a timer that starts after the radio problem from the physical layer is indicated expires (if the radio problem is resumed before the timer expires, the UE stops the timer);

(B) the random access procedure fails;

(C) the RLC fails.

After declaring RLF, the UE and/or the child IAB node may:

-remain in RRC _ connected CTED state;

-selecting a suitable cell and then initiating RRC re-establishment;

-entering RRC IDLE state if no suitable cell is found within a certain time after RLF is declared.

Various aspects of the embodiments disclose methods, apparatuses and systems for reducing the time for a downstream sub-IAB node/UE to respond to an upstream RLF. That is, the child IAB node/UE may be configured to perform certain actions when the parent node predicts that a potential upstream RLF will occur. In some aspects with similar delivery methods of the embodiments described above, an upstream potential RLF notification message may be sent to the child IAB node/UE. As disclosed, the message of the upstream potential RLF notification may be the same message as the upstream RLF notification described above, and thus, the two notifications may be interchanged throughout this application to indicate that the same procedure may be used to determine, process, and/or respond to the upstream potential RLF notification and/or the upstream RLF notification. That is, the conditions for triggering the messages may be the same (mutually used) or different; these two messages may be used interchangeably; and/or the processing or response to the message may be the same or different. In addition, the use of upstream potential RLF notifications and upstream RLF notifications is by way of example and not limitation.

In one embodiment, the upstream RLF notification message and/or the upstream potential RLF notification message may include a cell ID as part of the message in order to identify which cell has or may have an RLF problem.

Timer and physical layer

With respect to the above-mentioned radio problems in standard (a), the IAB node/UE may perform measurements of radio link strength/quality for a special cell (SpCell); determining whether the measured radio link strength/quality is below a configured and/or preconfigured threshold; and if it is determined that the measured radio link strength/quality is below a threshold, the lower layer (e.g., the physical layer) may report a specific indication (e.g., an "out of sync" indication signal) to the higher layer. In one example, if a certain number of consecutive "out of sync" indication signals, e.g., X1 (see N310 defined in the TS 38.331 specification) are received from the lower layer, the IAB node/UE determines that a radio problem may exist and starts a timer, e.g., T1 (see T310 defined in the TS 38.331 specification).

In order to send upstream potential RLF notification messages to the child nodes and the UE in a timely manner, in this embodiment, upon indicating or receiving a certain number (e.g., X) of consecutive "out of sync" indication signals from the lower layer of the parent node, the parent node predicts that a radio problem may exist and sends and/or transmits upstream potential RLF notification messages to the child IAB node/UE or other parent IAB nodes. In one embodiment, the number (X) of consecutive "out of sync" indications may be the same as the parameter X1 described above, in order to allow the same parameter to be reused. In an alternative embodiment, the parent IAB node may be configured or preconfigured by the network with new parameters, such as X2, for example, for the number of consecutive "out of synch" indications, where X2 is always less than or at most not greater than X1, so as not to affect the process of the normal RLF declaration of the parent node.

In other embodiments, unlike the timer T1 used to declare RLF described above, the new timer T2 may be configured or preconfigured by the network, with the value of T2 being less than or at most not greater than the value of T1. When a parent node detects a certain number of consecutive "out of sync" indications, the parent node may start both the T1 and T2 timers; at the expiration of T2, the parent node sends and/or transmits an upstream potential RLF notification message. In another alternative embodiment, T1 is no longer T310, instead, a parent node may only start a T2 timer when it detects a certain number of consecutive "out of sync" indications; upon expiration of T2, a timer T1 is started; in one example, for the purpose of declaring RLF, the value of T1+ T2 is equal to the original T310 timer value. Additionally, if T2 is configured with a value of 0, it may be considered a special case of the first embodiment. That is, in embodiments where the timer value is set to zero, the system may continue without any timer and therefore use the out-of-sync indication signal based on previously disclosed embodiments.

In another embodiment, the two embodiments described above are combined. In one example, both X2 and T2 are used for the purpose of timely sending upstream potential RLF notification messages. That is, the sending of the upstream potential RLF notification message may be based on a combination of a number of parameters indicated by consecutive "out of sync" configured or preconfigured by the network and a timer configured or preconfigured by the network. Thus, the parent node may start the timer T2 and while also continuing to determine whether a continuous "out of sync" threshold has been reached, and whichever is first triggered (e.g., the timer expires or the threshold is reached), an upstream potential RLF notification message may be sent and/or transmitted by the parent node.

Random access procedure failure

With respect to the above random access procedure failures in standard (B), in some embodiments, the number of TRANSMISSION/retransmission failures of a PRACH PREAMBLE may be recorded using an Information Element (IE) PREAMBLE _ TRANSMISSION _ COUNTER, and if the number of failures reaches some configured and/or preconfigured maximum number of TRANSMISSIONs (e.g., Y1), the parent node declares RLF.

In some embodiments, for PRACH preamble transmission, a new parameter may be used, e.g., Y2, which is a threshold that triggers delivery of an upstream potential RLF notification message. The new parameter (Y2) may be configured and/or preconfigured by the network and assigned to the parent node. If the transmission of the PRACH preamble of the parent node has reached Y2 threshold number of times, the parent node sends and/or transmits an upstream potential RLF notification message to the child node and the UE. Optionally, in one embodiment, a timer may be used to track failed PRACH preamble transmission attempts, wherein the timer provides an alternative method to determine events in which expiration of the timer or timer may trigger a notification to be sent and/or transmitted.

Radio Link Control (RLC) failure

Regarding the above-described RLC failure in standard (C), similar to standard (B), retransmission of RLC layer data units is also allowed until the maximum allowed number of transmissions is reached, e.g., Z1.

Additionally, in some embodiments, a new parameter associated with the number of RLC retransmissions (e.g., Z2), which is a threshold that triggers delivery of an upstream potential RLF notification message, may be configured and/or preconfigured by the network and assigned to the parent node. If the parent node's RLC retransmissions have reached Z2 times, the parent node sends and/or transmits an upstream potential RLF notification message to the child node and the UE.

Similar to previous embodiments, an optional timer may be used to track failed RLC transmission attempts, where the timer provides an alternative method to determine events where expiration of the timer or timer may trigger a notification to be sent and/or transmitted.

Declaring RLF or potential post-RLF processing

In some aspects of the different embodiments, based on receiving the upstream potential RLF notification message by the child IAB node/UE as described above, the child IAB node/UE may perform at least one of the following operations:

-selecting a suitable cell (parent node) and initiating RRC re-establishment;

-selecting one or more suitable cells (parent nodes) and initiating the establishment of redundant links in a dual connectivity or carrier aggregation manner;

if the child IAB node/UE already has dual/multi-connectivity to more than one parent node when receiving an upstream potential RLF notification message from one of the parent nodes, the child IAB node/UE may determine the next action or step that needs to be performed based on the specific implementation. That is, if priorities are not configured to cells associated with dual/multi-connectivity in a particular cell group, the child IAB node/UE may determine that no additional/extra operations are required. For example, the cell group may be a primary cell in a primary cell group list and a secondary cell in a secondary cell group list. In another embodiment, for the case where the network configures priorities of cells related to dual connectivity and/or carrier aggregation, the child IAB node/UE may determine to change the serving or scheduling cell in the cell list according to the priorities of the cells in the cell list. In one embodiment, when the serving cell has a radio link failure problem, another parent node for cell connection may control the backhaul traffic of the child IAB node/UE based on the parent node of the cell with the second highest priority.

In some aspects of various embodiments, the original parent IAB node may measure radio link strength/quality on the physical layer and then predict potential problems. The parent IAB node may then transmit the notification to another parent node in the form of an upstream potential RLF notification message. Based on the other parent IAB node receiving the upstream potential RLF notification message, the other parent IAB node may perform operations to initialize a random access procedure with a child IAB node/UE connected to the original parent IAB node. Thus, another (new) IAB parent node establishes an RRC connection with the child node.

The various embodiments are used to further describe and illustrate various aspects or aspects of the disclosed systems, devices, and methods with reference to the following description of the figures.

Fig. 10A illustrates an exemplary scenario of an upstream potential RLF notification that a threshold has been reached based on a higher layer on the IAB node having determined multiple "out of sync" indications from a lower layer. The figure further depicts the communication sent from the node (node a) and detected at the physical layer of the node by measuring the radio link strength/quality transmitted to the UE/IAB sub-node. Fig. 10A also depicts a different embodiment with a timer implemented as part of the notification determination. As previously described, based on multiple detected "out of sync" indications, the parent node (node a) may implement a timer T2 configured or preconfigured by the network, where the value of T2 is less than or at most not greater than the timer T1. That is, in some embodiments, when a parent node (node a) detects a certain number of consecutive "out of sync" indications, the parent node may start both T1 and T2 timers simultaneously. Further, upon expiration of timer T2, the parent node sends and/or transmits an upstream potential RLF notification message. Further, in an alternative embodiment, the upstream RLF notification may be transmitted to the UE/IAB sub-node upon expiration of timer T1, which may be started simultaneously with T2.

Fig. 10B illustrates another exemplary scenario similar to fig. 10A, in which a parent node may initially start timer T2 when a certain number of consecutive "out of synch" indications are detected by the lower layers of the parent node in this embodiment. The figure then depicts an embodiment in which upon expiration of T2, an upstream potential RLF notification is transmitted to the UE/IAB child node, and then a timer T1 is started. Further, in an alternative embodiment, an upstream RLF notification may be transmitted to the UE/IAB child node upon expiration of timer T1, which may be started in a serial manner with T2.

In both fig. 10A and 10B, the timer T2 may be configured or set to have a zero value, where the timer may be ignored and not used to determine when to transmit upstream potential RLF notifications to other nodes.

Fig. 10C illustrates another exemplary scenario of an upstream potential RLF notification, where the notification is based on a higher layer on the IAB node having determined that multiple PRACH preamble transmission attempts failed. In this figure, PRACH preamble transmission failures are calculated by using a counter, e.g. an IE, and if the count reaches a threshold Y2, the counter triggers the node to deliver upstream potential RLF notification messages to other nodes. As previously described, this parameter Y2 may be configured and/or preconfigured by the network and assigned to the parent node. That is, with further reference to fig. 10C, once the count of failed transmissions of the PRACH preamble of the parent node (node a) has reached the Y2 threshold number of times, the parent node (node a) may make this determination and send and/or transmit an upstream potential RLF notification message to the UE/IAB child node. The parent node (node a) may optionally continue to use the same (or a different) counter to count the number of failed PRACH preamble transmission attempts, and if the failed transmission count of the PRACH preamble of the parent node (node a) has reached another threshold Y1, the parent node sends and/or transmits an upstream RLF notification.

Fig. 10D illustrates another exemplary scenario for upstream potential RLF notification based on a higher layer on the IAB node having determined that multiple RLC layer data transfer attempts have failed. In this figure, RLC layer data transfer failures are calculated by using a counter, e.g., IE, and if the count reaches a threshold Z2, the counter triggers the node to deliver upstream potential RLF notification messages to other nodes. As previously described, this parameter Z2 may be configured and/or preconfigured by the network and assigned to the parent node.

Fig. 10E depicts an exemplary sequence of messages for a parent IAB node to communicate with another parent IAB node and a UE/IAB child node. In this figure, both node a and node B are parent nodes to UE/IAB child nodes with dual connectivity (or carrier aggregation as shown in fig. 10F). With further reference to fig. 10E, the UE/IAB child node is in RRC _ Connected mode with node a, but based on the disclosed embodiments, if node a determines that there may be a radio link failure problem or there has been a radio link failure, the parent node (node a) may send and/or transmit an upstream potential RLF notification or upstream RLF notification to another parent node (node B) to notify the UE/IAB child node of the potential failure of node a's radio link. That is, the node B may then control the radio link connection by initializing the random access procedure and the RRC connection setup procedure. After the random access procedure is successfully completed and the RRC connection establishment procedure is also completed, the connection may be automatically changed to place the UE/IAB child node in RRC _ Connected mode with the node B. Thus, node B may become the serving cell for a UE/IAB child node based on an upstream potential RLF notification sent from a first parent node (node a) to another parent node (node B).

Referring to fig. 10F, in embodiments supporting carrier aggregation, multiple other parent IAB nodes (node X) are depicted as part of a serving cell group for a UE/IAB child node. Thus, based on the upstream potential RLF notifications transmitted to other parent nodes, the random access procedure and RRC connection establishment procedure are conducted at node B, which will have the highest priority and be selected based on its having the highest priority for the set of node a, node B, …, node X, after a link failure for node a, since node a is the highest priority initially in the set and node B is the second highest priority. In this example, if node X has a higher priority than node B, a change will be made for node X with a higher priority than node B based on the upstream potential RLF notifications transmitted to other parent nodes. Handling radio link monitoring and RFL

Further, when the NR system operates bandwidth part by bandwidth part (BWP); the serving cell may be configured with one or more BWPs and the maximum number of BWPs per serving cell is specified as MaxNum _ BWP, e.g., 4 in the Rel-153 GPP specification.

In the configured BWP, the BWP of ActiveBWPNum is configured as the active BWP of the serving cell, e.g., ActiveBWPNum ═ 1 in the Rel-153 GPP specification.

Generally, for each DL BWP of the SpCell, a set of resource indexes may be configured for the IAB node/UE through a corresponding set of higher layer parameters, RadioLinkMonitoringRS, for radio link monitoring through a higher layer parameter failureDetectionResources. The higher layer parameter RadioLinkMonitoringRS provides the IAB node/UE with either a CSI-RS resource configuration Index (provided by the higher layer parameter CSI-RS-Index) or a SS/PBCH block Index (provided by the higher layer parameter ssb-Index). IAB node/UE may be configured with a maximum of N_LR-RLMA radio link monitoring rs for link recovery procedures and radio link monitoring. According to the maximum number L of candidate SS/PBCH blocks per field, at N_LR-RLMMaximum N in RadioLinkMonitoringRS_RLMOne radiolink monitoring rs may be used for radio link monitoring and at most two radiolink monitoring rss may be used for the link recovery procedure.

When the UE is not provided with the higher layer parameter RadioLinkMonitoringRS, the UE does not expect to use more than N_RLMA radio link monitoring rs.

N for different values of L is given in Table 5-1_LR-RLMAnd N_RLMThe value of (c).

Tables 1 to 1: n as a function of the maximum number L of SS/PBCH blocks per field_LR-RLMAnd N_RLM

L	N_LR-RLM	N_RLM
			4	2	2
8	6	4
			64	8	8

Among these, in the Rel-153 GPP specification, these parameters are defined as follows:

even if each DL BWP is configured with a set of resources for radio link monitoring, the IAB node/UE typically does not need to monitor the downlink radio link quality in Downlink (DL) BWPs other than the active DL BWP on the primary cell. Thus, RLF of the Rel-15 NR system actually occurs for one BWP (active DL BWP) rather than the entire bandwidth.

For IAB systems, backhaul RLF can cause a more serious problem because it disrupts the network for all nodes/UEs attached to the network. Therefore, based on the above BWP-based NR system features, the following new designs are proposed:

in the first embodiment, the IAB node and/or UE needs to monitor all configured DL BWPs (including active DL BWPs) on the primary cell, although this is at the cost of more power consumption on the IAB node and/or UE side, the IAB node as base station has no problem in power saving.

Although in the second embodiment, for more flexibility, the network may configure the IAB node and/or the UE with a set of DL BWPs (one or more DL BWPs) to be monitored; such configurations may be signaled in RRC signaling only or Downlink Control Information (DCI) only or in RRC signaling and DCI together. If RRC signaling is used, it may be dedicated RRC signaling or broadcast RRC signaling, or both dedicated and broadcast RRC signaling. In this patent, such signaling is referred to as BWP Monitoring Configuration (BMC) signaling.

In some embodiments regarding BMC signaling, BMC signaling may be the same as BWP configuration signaling, e.g., in BWP configuration signaling, the network configures the IAB node and/or UE with a BWP set, { BWP #2, BWP #3, BWP #4 }; if BMC is the same as BWP configuration signaling, in other words, there is no independent BMC signaling, the IAB node and/or the UE monitors the radio link for all BWP #2, BWP #3 and BWP # 4. In such cases, the IAB node and/or UE always monitors all configured BWPs; the first embodiment described above is a special case of the second embodiment.

Although in another embodiment with respect to BMC signaling, BMC signaling may be different from BWP configuration signaling, e.g., in BWP configuration signaling, the network configures the IAB node and/or UE with a BWP set, { BWP #2, BWP #3, BWP #4 }; if the BMC and BWP configuration signaling are different and the network also configures the IAB node and/or UE with { BWP #2, BWP #3} in BMC signaling, the IAB node and/or UE monitors the radio link for both BWP #2 and BWP # 3.

When the BWP configuration signaling is different from the BMC signaling, the BMC signaling may be independent of the BWP configuration signaling; in this case, the BWP index carried in the BMC signaling is the actual BWP index; in the above example, the configured BWP set is { BWP #2, BWP #3, BWP #4} and the configured monitoring BWP set is { BWP #2, BWP #3}, then the IAB node and/or UE monitors the radio link for BWP #2, BWP # 3; or the BMC signaling may be dependent on BWP configuration signaling; in this case, the BWP index carried in the BMC signaling is the BWP index in the configured BWP set; in the above example, the configured BWP set is { BWP #2, BWP #3, BWP #4} and the configured monitoring BWP set is { BWP #2, BWP #3}, and then the IAB node and/or UE monitors the radio link for BWP #3, BWP # 4.

While in the third embodiment, the IAB node/UE still does not need to monitor the downlink radio link quality in the Downlink (DL) BWP except for the active DL BWP on the primary cell. However, for the serving cell in the IAB system, one or more DL BWPs may be configured as active DL BWPs; in other words, ActiveBWPNum may be greater than 1. The configuration signaling the active DL BWP may be sent in RRC signaling only or Downlink Control Information (DCI) only or in both RRC signaling and DCI. If RRC signaling is used, it may be dedicated RRC signaling or broadcast RRC signaling, or both dedicated and broadcast RRC signaling.

The active DL BWP configuration signaling may process the active BWP index carried in the signaling in a similar manner as the second embodiment.

For an IAB node and/or UE configured to monitor one or more BWPs of a serving cell, when a lower layer measures a radio link associated with that BWP, all reports relating to, for example, "out of sync" or "in sync" should include the corresponding BWP ID so that the higher layer knows the radio link quality of each BWP.

In one embodiment, if a higher layer (e.g., parent node in the case herein) of the IAB node declares that there is an RLF for at least one active DL BWP of the serving cell, or predicts that there is a potential RLF that will soon occur for at least one active DL BWP of the serving cell, the network may configure a new set of active DL BWPs that may contain one or more than one active DL BWP for the IAB node only if all active DL BWPs experience or are likely to experience an RLF condition; in yet another embodiment, the network may configure a new active DL BWP set that may contain one or more than one BWP only through BWP handover signaling;

the BWP handover signaling includes an ID of the new BWP set or the new active BWP set, which may carry the new active BWP index in the signaling in a similar manner as described above with respect to the second and third embodiments of processing the BWP index.

The BWP switching signaling is signaled in RRC signaling only or Downlink Control Information (DCI) only or in both RRC signaling and DCI. If RRC signaling is used, it may be dedicated RRC signaling or broadcast RRC signaling, or both dedicated and broadcast RRC signaling.

Note that in some embodiments, among all the above BWP configuration and BWP handover configuration signaling that may be carried by RRC signaling, or DCI, or RRC signaling and DCI, the configuration signaling carries a set of configurations that are only used by the IAB node and/or IAB-capable UE; in yet another embodiment, the configuration signaling carries more than one set of configurations, e.g., two sets of configurations, where the first set of configurations is used by normal NR UEs without IAB capability and the second set of configurations is used by IAB nodes and/or IAB capable UEs.

Furthermore, since in the current NR design, the IAB node/UE may be configured with a maximum of N_LR-RLMA radio link monitoring rs for link recovery procedures and radio link monitoring. According to the maximum number L of candidate SS/PBCH blocks per field, at N_LR-RLMMaximum N in RadioLinkMonitoringRS_RLMOne RadioLinkMonitoringRS can be used for radio link monitoring and at most two RadioLinkMonitoringRSs can be used for the link recovery process; in order to have fast link recovery, in the new design of the IAB system, up to M radio link monitoring rss can be used for the link recovery procedure, where M is larger than 2, e.g. 4. Thus, N can be substituted by_LR-RLMSet to a larger value, or introduce a new N dedicated only to the IAB system_LR-RLMAnd will be present at N_LR-RLMFor normal NR systems to allocate more radiolinkminigoringrs.

Fig. 11 is a diagram illustrating an example of a radio protocol architecture for the control plane and the user plane in a mobile communication network. The radio protocol architecture of the UE and/or the gbodeb may be shown in three layers: layer 1, layer 2 and layer 3. Layer 1(L1 layer) is the lowest layer and implements various physical layer signal processing functions. Layer 2(L2 layer) is above the physical layer and is responsible for the link between UEs and/or gnodes above the physical layer. In the user plane, the L2 layer may include a Medium Access Control (MAC) sublayer, a Radio Link Control (RLC) sublayer and a Packet Data Convergence Protocol (PDCP) sublayer, which terminate at the network side at the gbodeb. Although not shown, the UE may have several upper layers above the L2 layer, including a network layer (e.g., IP layer) that terminates at a PDN gateway on the network side, and an application layer (e.g., far end UE, server, etc.) that terminates at the other end of the connection. The control plane also includes a Radio Resource Control (RRC) sublayer in layer 3 (layer L3). The RRC sublayer is responsible for obtaining radio resources (i.e., radio bearers) and for configuring lower layers between the IAB node and/or UE and the IAB bearers using RRC signaling.

Fig. 12 depicts an example of a mobile network infrastructure 1200 in which a plurality of UEs and IAB nodes comprising components of the computing device shown in fig. 11 are shown in communication with each other. In one embodiment,

multiple UEs

1204, 1208, 1212, 1218, 1222 are connected to a set of

IAB nodes

1252, 1258, and the

IAB nodes

1252, 1258 communicate 1242 with each other and/or with an IAB carrier 1256 using various aspects of the present embodiment. That is, the

IAB nodes

1252, 1258 may send discovery information to other devices on the network (e.g., send the cell ID and resource configuration of the transmitting node to the receiving node) and also provide MT functionality connected to the IAB bearer 1256. The example of the UE may also be receiving discovery information and, if not barred, requesting a connection and using resources by transmitting a connection request to the IAB node and/or the IAB bearer. In one embodiment, the IAB bearer 1256 may restrict or prohibit any connection requests from the UE because they are already connected to other IAB nodes and devote resources to backhaul traffic. In another embodiment, the IAB bearer 1256 may accept the connection request of the UE but prioritize the IAB node backhaul traffic over any connections used by the UE. In yet another embodiment, the IAB carrier 1256 and/or the

IAB nodes

1252, 1258 may detect and communicate an RLF according to aspects of the current embodiment, which may then propagate down between the IAB nodes and the UE, where a child node (e.g., an IAB node or UE in the network) may detect an upstream connection failure.

Fig. 13 shows an example of a top-level functional block diagram of a computing device implementation 1300. The exemplary operating environment is shown as a computing device 1320 that includes a processor 1324, such as a Central Processing Unit (CPU), addressable memory 1327, an external device interface 1326 (e.g., an optional universal serial bus port and associated processes and/or an ethernet port and associated processes), and an optional user interface 1329 (e.g., an array of status lights and one or more toggle switches, and/or a display, and/or a keyboard and/or an inter-pointer system and/or a touch screen). Optionally, the addressable memory may be, for example: flash memory, eprom, and/or a disk drive or other hard drive. These elements may communicate with each other via a data bus 1328. In some embodiments, via an operating system 1325 (such as an operating system supporting a web browser 1323 and application programs 1322), the processor 1324 may be configured to perform steps of a process to establish communication channels and processing according to the embodiments described above.

Fig. 14 is a flow diagram of an exemplary process 1400 of handling Radio Link Failure (RLF) in a wireless relay network, wherein the system comprises a computer and/or computing circuitry that may be configured to perform the depicted steps. In addition, the wireless relay network may have a carrier node, a first parent node, a second parent node, a first child node, and a second child node, wherein the carrier node may be an Integrated Access and Backhaul (IAB) node connected to the core network, and wherein the first parent node, the second parent node, the first child node, and the second child node may each have Mobile Terminal (MT) functionality capability. The method depicted in the flow chart comprises the following steps: (a) transmitting, by a first child node (IAB node a) to a second child node (UE/IAB child node), a message comprising an upstream RLF notification based on an upstream radio link failure between the first child node and the first parent node (IAB parent node 1), wherein the first child node and the second child node are in a connected mode (step 1410); (b) receiving, by a second child node in communication with the first child node, a message including an upstream RLF notification, wherein the second child node may be: an MT-capable User Equipment (UE) or an Integrated Access and Backhaul (IAB) node (step 1420); (c) initiating, by the second child node, a cell selection procedure with respect to the second parent node (IAB parent node 2) prior to expiration of a timer (Txxx) set for a time period and based on the upstream RLF notification message received from the first child node, wherein the initiation of cell selection uses an MT function (step 1430); (d) monitoring, by the second child node, for an incoming message from the first child node during a timer (Tyyy) set within another period of time prior to the initiating step, wherein the incoming message indicates whether the connection between the first child node and the first parent node has been restored (step 1440); and (e) performing, by the second child node, a reestablishment process with respect to the first child node if an upstream restoration notification that the connection between the first child node and the first parent node has been restored is received from the first child node before the timer expires.

Fig. 15A is a functional block diagram of a wireless node device, which may be a parent IAB node that may communicate with an upstream IAB carrier and downstream UEs and/or child IAB nodes. The parent IAB node may include a processor and two transceivers, where each transceiver may have a transmitter component and a receiver component, and in some embodiments one transceiver may be used to connect to and communicate with an upstream device (upstream radio link) and another transceiver may be used to connect to and communicate with a downstream device (downstream radio link). That is, in one embodiment, one transceiver may be dedicated to communicating with an IAB bearer/parent IAB node (via a Mobile Terminal (MT) component) and another transceiver may be dedicated to communicating with a child IAB node and/or UE (via a Distribution Unit (DU) component). The mobile terminal components may provide the functionality to terminate the radio interface layer, similar to the UE, but implemented on the IAB node as disclosed herein. The exemplary wireless node device depicted in fig. 15A may also include a processor, which may include a Mobile Terminal (MT) component and a Distributed Unit (DU) component. In this embodiment, the MT component may be configured to monitor the radio link and detect radio link conditions, such as Radio Link Failure (RLF), on the upstream radio link. The MT component may also include connection management that may provide at least cell selection, connection establishment and re-establishment functions. The DU component may be configured to communicate with the IAB bearer for relay configuration. The DU component may be further configured to process the detected radio link condition and transmit a notification indicative of the radio link condition to a downstream node.

Fig. 15B is a functional block diagram of a wireless terminal device, which may be a UE and/or a child IAB node, communicating with an IAB bearer or an upstream parent IAB node (itself in communication with an IAB bearer). The wireless end devices may include a transceiver having a transmitter and a receiver for communicating with other upstream IAB carriers/nodes. The exemplary wireless node device depicted in fig. 15B may also include a processor, which may include a Mobile Terminal (MT) component and a handler component. In this embodiment, the MT component may be configured to monitor the radio link and detect any Radio Link Failure (RLF). The MT component may also include connection management that may provide at least cell selection, connection establishment and re-establishment functions. The handler component may be configured to receive a notification from a parent node (e.g., an IAB carrier or an upstream parent IAB node) indicating a radio condition of an upstream radio link of the parent node. The handler component may also be configured to process the received notification from the upstream node in accordance with aspects of the different embodiments. In processing the notification, the handler component may instruct connection management to perform a specified action (e.g., cell selection).

Fig. 16 illustrates an embodiment of a UE and/or base station including components of a computing device 1600 in accordance with an embodiment of the present invention. The illustrated device 1600 may include an antenna assembly 1615, a communication interface 1625, a processing unit 1635, a user interface 1645, and addressable memory 1655. In some embodiments, antenna assembly 1615 may be in direct physical communication 1650 with communication interface 1625. Addressable memory 1655 may include a Random Access Memory (RAM) or another type of dynamic storage device, a Read Only Memory (ROM) or another type of static storage device, a removable memory card, and/or another type of memory for storing data and instructions that may be used by processing unit 1635. User interface 1645 may provide a user with the ability to input information to device 1600 and/or receive output information from device 1600. Communication interface 1625 may include a transceiver that enables the mobile communication device to communicate with other devices and/or systems via wireless communication (e.g., radio frequency, infrared, and/or visual optical, etc.), wired communication (e.g., wire, twisted-pair cable, coaxial cable, transmission line, fiber optic cable and/or waveguide, etc.), or a combination of wireless and wired communication. Communication interface 1625 may include a transmitter to convert baseband signals to Radio Frequency (RF) signals and/or a receiver to convert RF signals to baseband signals. Communication interface 1625 may also be coupled (not shown) to antenna assembly 1615 for transmitting and receiving RF signals. Additionally, the antenna assembly 1615 may include one or more antennas for transmitting and/or receiving RF signals. The antenna assembly 1615 may receive RF signals from the communication interface and transmit and provide the signals to the communication interface, for example.

The above features are applicable to 3 rd generation partnership projects; technical specification group radio access network; integrated access and backhaul studies; (release 15) for 3GPP TR 38.874V0.3.2(2018-06) and applicable standards.

The foregoing description presents the best mode contemplated for carrying out the embodiments of the present invention, as well as the manner and method of practicing those embodiments, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which they pertain to practice those embodiments. However, the embodiments of the invention are susceptible to modifications and alternative constructions from those fully equivalent described above. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed. On the contrary, the invention is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention. For example, the steps in the processes described herein need not be performed in the same order as presented, but may be performed in any order. Further, steps that have been presented as being performed separately may, in alternative embodiments, be performed concurrently. Also, steps that have been presented as being performed concurrently may be performed separately in alternative embodiments.

< summary of the invention >

In one example, there is provided a method of handling radio link monitoring and Radio Link Failure (RLF) in a wireless relay network having a carrier node, a first parent node (IAB node a), a second parent node (IAB node B), and a child node (IAB node/UE), wherein the carrier node is an Integrated Access and Backhaul (IAB) node connected to a core network, the method comprising: monitoring, by the child node, radio link conditions on one or more bandwidth portions (BWPs) of the parent node; detecting, by the child node, a potential RLF in at least one active Downlink (DL) BWP; determining, by the child node, an RLF or potential RLF based on the monitored BWP of the parent node; and configuring, by the network, an active BWP handover to maintain good radio conditions for an IAB parent backhaul radio link in active BWP.

In one example, a node comprises: monitoring circuitry configured to monitor radio link conditions on one or more bandwidth portions (BWPs) of a parent node; and a detection circuit configured to detect a Radio Link Failure (RLF) in at least one downlink BWP.

In one example, a method of a node, comprising: monitoring radio link conditions on one or more bandwidth portions (BWPs) of a parent node; and detecting a Radio Link Failure (RLF) in the at least one downlink BWP.

< Cross reference >

The non-provisional application claims priority from provisional application 62/737,904 filed 2018, 9, 27, in accordance with 35 u.s.c. § 119, the entire content of which is hereby incorporated by reference.

Claims

1. A method of handling radio link monitoring and Radio Link Failure (RLF) in a wireless relay network having a carrier node, a first parent node (IAB node a), a second parent node (IAB node B), and a child node (IAB node/UE), wherein the carrier node is an integrated access and backhaul (1AB) node connected to a core network, the method comprising:

monitoring, by the child node, radio link conditions on one or more bandwidth portions (BWPs) of the parent node;

detecting, by the child node, a potential RLF in at least one active Downlink (DL) BWP;

determining, by the child node, an RLF or potential RLF based on the monitored BWP of the parent node; and

configuring, by the network, an active BWP handover to maintain an IAB parent backhaul radio link in active BWP based on the radio link conditions.

2. A node, comprising:

monitoring circuitry configured to monitor radio link conditions on one or more bandwidth portions (BWPs) of a parent node; and

a detection circuit configured to detect a Radio Link Failure (RLF) in at least one downlink BWP.

3. A method of a node, comprising:

monitoring radio link conditions on one or more bandwidth portions (BWPs) of a parent node; and

radio Link Failure (RLF) in at least one downlink BWP is detected.