PCI collision avoidance in 5G mobile IAB

Abstract

A Physical Cell Identity (PCI) collision avoidance method in a wireless network, the wireless network comprising a first base station controlling a first cell having a first PCI, the method comprising: determining a collision between the first PCI and a PCI of another cell in the vicinity of the first cell; and activating a second cell having a second PCI, wherein the second PCI is different from the first PCI.

Description

Technical Field

[0001] The present invention generally relates to methods used in a process for mitigating signal interference involving an Integrated Access and Backhaul (IAB) node. Background Art

[0002] Wireless communication systems are deployed in large numbers to address a wide range of applications from mobile broadband, massive machine type communications to Ultra Reliable Low Latency Communication (URLLC). Such systems allow multiple user equipments (UEs) or mobile terminals to share a wireless medium to exchange several types of data content (e.g., video, voice, messaging, ...) over a radio access network (RAN) through one or more base stations. Traditionally, base stations are wired to the core network (e.g., via optical fiber), forming an intermediate network called backhaul (BH).

[0003] Examples of such wireless multiple-access communication systems include systems based on the 3rd Generation Partnership Project (3GPP-RTM) standards such as fourth generation (4G) Long Term Evolution (LTE) or the more recent fifth generation (5G) New Radio (NR) systems, or systems based on the IEEE 802.11 standards such as WiFi.

[0004] Due to the increase in the number of users and higher throughput requirements, the need for network densification increases.

[0005] Faced with the problem of high deployment cost and time of wired backhaul networks with network densification, 3GPP proposed wireless backhaul, also known as integrated access and backhaul (IAB) in the recent Release 16 for 5GNR, where instead of optical fiber, a portion of the wireless (i.e., radio) spectrum is used for backhaul connections of base stations. Wireless backhaul communications (between base stations) can use the same radio resources as access communications (between base stations and UEs).

[0006] IAB is proven to be a competitive alternative to fiber-based backhaul in dense areas or hard-to-cover areas because IAB allows for scalable and rapid installation without the burden of wiring base stations.

[0007] IAB will most likely operate in the millimeter wave (mmWave) band to achieve the required Gbps (gigabits per second) data rates. However, mmWave is known to suffer from strong attenuation of signal strength in some weather conditions (rain, fog) and from obstructions if they are in the path between the transmitter and the receiver.

[0008] Building on the fixed IAB foundation that was retired in Release 16 and Release 17, 3GPP is now considering a mobile IAB system and architecture as part of the Release 18 framework to address scenarios that focus on mobile IAB nodes mounted on vehicles. In such scenarios, the mobile IAB nodes may be referred to as vehicle mounted repeaters (VMRs), providing 5G coverage / capacity to onboard and / or surrounding UEs.

[0009] Technical benefits of using vehicle repeaters include enabling the relay vehicle to obtain better macro coverage than nearby UEs due to better RF / antenna capabilities, among others, thereby providing the UE with a better link to the macro network. Additionally, vehicle repeaters are expected to have less stringent power / battery constraints than UEs.

[0010] Urban environments are typically characterized by a high density of users and the presence of a large number of vehicles (e.g., public / private passenger transport, freight transport, food trucks, ...). The speed of some vehicles may be quite low or at least similar to pedestrian speed, and some of these vehicles may even be temporarily stationary. Some of these vehicles (e.g., buses, trains, or trams) may have predictable routes and / or restricted mobility areas (e.g., some vehicles (such as food trucks or promotional vehicles, etc.) may be located outside a stadium or show venue), while other vehicles may have predictable fixed locations (e.g., taxis).

[0011] 3GPP is considering that such vehicles can provide opportunities to increase network coverage and connectivity to UEs inside the vehicle or even to UEs near the vehicle by installing onboard base stations (or base station elements) that will act as repeaters on these vehicles. These repeaters will rely on 5G wireless backhaul (usually IAB, or integrated access and backhaul) for connecting to fixed donor devices. Thus, based on the fixed IAB foundations set forth in Release 16 and Release 17, 3GPP is now considering mobile IAB systems and architectures as part of the Release 18 framework to address scenarios focusing on mobile IAB nodes installed on vehicles (e.g., buses, trains, taxis). In such scenarios, mobile IAB nodes may also be referred to as vehicle-mounted repeaters (VMRs), thereby providing 5G coverage / capacity to UEs onboard and / or around them. The technical benefits of using vehicle repeaters include the ability to enable relay vehicles to obtain better coverage than nearby UEs due to better RF / antenna capabilities, as well as others, thereby providing UEs with better links to the macro network. Additionally, vehicle relays are expected to have less stringent power / battery constraints than UEs.

[0012] As a legacy base station, the mobile IAB node manages one or several cells where the UE can reside and can be connected to the network. Typically, the UE is configured to periodically measure cells in the neighborhood. These measurements are performed at the initialization of the UE to search for candidate cells for the first connection to the network, and are also performed when the UE is connected or in an idle / inactive state to search for cells with better connection quality. Once a candidate cell is found, the UE measures one or more parameters of the signal received from the candidate cell. These parameters may include reference signal received power (RSRP) or reference signal received quality (RSRQ). Typically, the UE measures RSRP or RSRQ on a signal synchronization block (SSB). In addition, the UE derives the necessary information required to access the cell from the SSB. In particular, the UE obtains the physical cell identity (PCI) of the cell that can be retrieved from the SSB. The SSB contains two synchronization signals: PSS (primary synchronization signal) and SSS (secondary synchronization signal). The PSS contains a physical layer identifier (an integer from 0 to 2), and the SSS contains a group number (an integer from 0 to 335). The PCI value is obtained by combining these two values ​​(physical layer identification + 3 x group number), providing an integer from 0 to 1007. Thus, due to this limited range, the PCI value is not a unique identifier.

[0013] In PCI planning, adjacent or neighboring cells cannot be assigned the same PCI. In fact, PCI conflicts with neighboring cells with the same PCI can introduce synchronization delays for UEs performing cell search in the overlapping area of ​​​​the cells. In addition, this PCI conflict may cause high error rates and / or decoding failures for physical channels encrypted with PCI, and may also generate some handover failures. Therefore, the PCI planning algorithm aims to avoid PCI conflicts by maximizing the PCI reuse distance (i.e., the physical separation between two cells with the same PCI value).

[0014] In addition, PCI confusion at the UE may also occur in the following cases:

[0015] - If two neighboring cells have the same PCI mode 3 result, these cells use the same PSS, resulting in UE synchronization delay,

[0016] - If two neighboring cells have the same PCI mode 4 result, this may introduce interference to the demodulation reference signal (DMRS),

[0017] - If two neighboring cells have the same PCI modulo 30 result, this may introduce inter-cell uplink interference.

[0018] In the case of mobile base stations, such as mobile IAB nodes or vehicle mounted repeaters (VMRs), the risk of PCI conflicts and confusion is high compared to a topology formed by stationary base stations, and even with high quality PCI planning algorithms, it may still prove difficult or even impossible to avoid PCI conflicts when the mobile base station moves in a large area. Therefore, it is necessary to be able to change the PCI value of one or several cells controlled by the mobile base station while the mobile base station is serving UEs. In addition, it would be beneficial to avoid service interruptions at UEs served by the mobile base station when changing the PCI value of the serving cell.

[0019] The present invention is directed to addressing some of the above-mentioned problems of a wireless communication system incorporating a mobile base station. Summary of the invention

[0020] According to a first aspect of the present invention, there is provided a physical cell identity conflict avoidance (PCI) method in a wireless network, the wireless network comprising a first base station, the first base station controlling a first cell having a first PCI, the method comprising:

[0021] determining a conflict between the first PCI and a PCI of another cell near the first cell; and

[0022] activating a second cell having a second PCI (for example, when a conflict between the first PCI and the PCI of another cell near the first cell is determined), wherein the second PCI is different from the first PCI (and the PCI of the other cell) (and therefore does not cause a conflict with the first PCI (and the PCI of the other cell)).

[0023] Optionally, while the first cell is still active, the second cell is activated by the first base station (i.e., so that the first cell having the first PCI and the second cell having the second different and non-conflicting PCI are activated simultaneously). Optionally, the step of determining the conflict between the first PCI and the PCI of another cell near the first cell is performed by the first base station. In one example, the cell near the first cell may correspond to a cell that is adjacent to the first cell and covers a geographical area that may partially or completely overlap with the geographical area covered by the first cell. In another example, the cell near the first cell may correspond to a cell that is not adjacent to the first cell but is adjacent to a third cell (which is also adjacent to the first cell). Optionally, the step of determining the conflict between the first PCI and the PCI of another cell near the first cell is performed by a second base station of the wireless network. Optionally, the step of determining the conflict between the first PCI and the PCI of another cell near the first cell is performed by a core network that controls the wireless network.

[0024] Optionally, the method further comprises the following steps: determining a value of the second PCI. Optionally, the step of determining the value of the second PCI is performed by the first base station. Optionally, the step of determining the value of the second PCI is performed by a second base station of the wireless network. The step of determining the value of the second PCI may be performed by a central unit (CU) of the first base station and / or the second base station.

[0025] Optionally, the step of determining the value of the second PCI is performed by a core network that controls the wireless network.

[0026] Optionally, the step of activating the second cell is performed by a distributed unit (DU) of the first base station controlling the first cell. Optionally, the step of activating the second cell is performed in response to a request of a central unit (CU) of the first base station.

[0027] Optionally, the first cell is controlled by a first DU of the first base station, and the step of activating the second cell is performed by a second DU of the first base station. Optionally, the step of activating the second cell is performed in response to a request of a CU of the first base station.

[0028] Optionally, the first cell is controlled by a distributed unit (DU) of the first base station, and the step of activating the second cell is performed by the DU of the second base station. Optionally, the step of activating the second cell is performed in response to a request of a CU of the second base station.

[0029] In some examples, wherein the wireless network serves a user equipment initially connected to the first base station via a radio link in the first cell, the method may further include the following steps:

[0030] Following activation of the second cell, the user equipment is connected to the first base station via a radio link in the second cell.

[0031] In some examples, wherein the wireless network serves a user equipment initially connected to the first base station via a radio link in the first cell, the method may further include the following steps:

[0032] Following activation of the second cell, the user equipment is connected to a second base station via a radio link in the second cell.

[0033] The first distributed unit and / or the second distributed unit may be a logical distributed unit entity.

[0034] Optionally, both the first distributed unit and the second distributed unit are logical distributed unit entities sharing the same physical layer. Optionally, both the first distributed unit and the second distributed unit are logical distributed unit entities having separate physical layers.

[0035] Optionally, the first base station is a next generation radio access network node.

[0036] Optionally, the first base station is a CU of an integrated access and backhaul (IAB) donor node.

[0037] Optionally, the first base station is a CU of an integrated access and backhaul (IAB) donor, and the DU or DUs are DUs of IAB nodes of an IAB topology controlled by the donor CU. The IAB node may be a mobile IAB node.

[0038] Optionally, the method further includes the following steps: deactivating the first cell.

[0039] Optionally, the method further includes the following step: deactivating the first DU.

[0040] According to a second aspect of the present invention, there is provided a base station configured to perform the method according to the first aspect.

[0041] According to a third aspect of the present invention, there is provided a method for a central unit (CU) of an integrated access and backhaul (IAB) donor node, the CU of the IAB donor node controlling an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (DU) of the IAB node of the IAB topology, the method comprising:

[0042] determining a conflict between a physical cell identifier (PCI) of the first cell and a PCI of another cell near the first cell;

[0043] (e.g., when a conflict between the first PCI and a PCI of another cell near the first cell is determined) obtaining a new PCI that does not cause a conflict with the PCI of another cell near the first cell (or the PCI of the first cell itself); and

[0044] The IAB node is instructed to activate a second cell having the new PCI by using the first DU of the IAB node.

[0045] Optionally, the second cell is activated while the first cell is still active (i.e., the first cell having the first PCI and the second cell having the second different and non-conflicting PCI are activated simultaneously). In some examples, where the user equipment is initially connected to the IAB donor node via a radio link in the first cell, the method may further include the following steps:

[0046] and triggering an intra-DU handover of the user equipment from the first cell to the second cell.

[0047] Optionally, the method further comprises the following steps:

[0048] Instruct the IAB node to deactivate the first cell using the first DU of the IAB node.

[0049] According to a fourth aspect of the present invention, there is provided a method for a central unit (CU) of an integrated access and backhaul (IAB) donor node, the CU of the IAB donor node controlling an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (DU) of the IAB node of the IAB topology, the method comprising:

[0050] determining a conflict between a physical cell identifier (PCI) of the first cell and a PCI of another cell near the first cell;

[0051] (e.g., when a conflict between the first PCI and a PCI of another cell near the first cell is determined) obtaining a new PCI that does not cause a conflict with the PCI of another cell near the first cell (or the PCI of the first cell itself); and

[0052] The IAB node is instructed to activate a second cell having the new PCI by using a second DU of the IAB node.

[0053] Optionally, the second cell is activated while the first cell is still active (i.e., the first cell having the first PCI and the second cell having the second different and non-conflicting PCI are activated simultaneously). In some examples, where the user equipment is initially connected to the IAB donor node via a radio link in the first cell, the method may further include the following steps:

[0054] and triggering an inter-DU handover of the user equipment from the first cell to the second cell.

[0055] Optionally, the method further comprises the following steps:

[0056] Instruct the IAB node to deactivate the first cell using the first DU of the IAB node.

[0057] Optionally, the method further comprises the following steps:

[0058] Instruct the IAB node to deactivate the first DU.

[0059] According to a fifth aspect of the present invention, there is provided a method for a central unit (CU) of a target integrated access and backhaul (IAB) donor node, the CU of the target IAB donor node controlling a target IAB topology, the method comprising:

[0060] receiving, from a CU of a source IAB donor node controlling a source IAB topology, a node migration request for migrating an IAB node of the source IAB topology, the IAB node including a first distributed unit (DU) having established a first cell having a first physical cell identity (PCI);

[0061] Using the CU of the target IAB donor node, obtaining a new PCI that does not cause a conflict with a PCI of another cell near the first cell (or a PCI of the first cell itself); and

[0062] The second DU of the IAB node indicating the migration of the source IAB topology establishes a second cell with the new PCI by using the CU of the target IAB donor node.

[0063] Optionally, the second cell is activated while the first cell is still active (ie, the first cell with the first PCI and the second cell with the second different and non-conflicting PCI are activated at the same time). Optionally, the method further comprises the following steps:

[0064] Instruct the IAB node to deactivate the first cell using the first DU of the IAB node.

[0065] Optionally, the method further comprises the following steps:

[0066] Instruct the IAB node to deactivate the first DU.

[0067] According to a sixth aspect of the present invention, there is provided a base station, which is configured to perform a physical cell identity (PCI) conflict avoidance method in a wireless network, the wireless network comprising the base station, the base station controlling a first cell having a first PCI, the base station comprising:

[0068] means for determining a conflict between the first PCI and a PCI of another cell in the vicinity of the first cell; and

[0069] A means for activating a second cell having a second PCI (e.g., when a conflict between the first PCI and the PCI of another cell near the first cell is determined), wherein the second PCI is different from the first PCI (and the PCI of another cell near the first cell). Optionally, the second cell is activated while the first cell is still active (i.e., such that the first cell having the first PCI and the second cell having a second different and non-conflicting PCI are activated simultaneously).

[0070] According to a seventh aspect of the present invention, there is provided an integrated access and backhaul (IAB) donor node, comprising a central unit (CU), the CU being configured to control an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (DU) of an IAB node of the IAB topology, the IAB donor node comprising:

[0071] means for determining a conflict between a physical cell identity (PCI) of the first cell and a PCI of another cell in the vicinity of the first cell;

[0072] means for obtaining a new PCI that does not cause a conflict with the PCI of another cell near the first cell (or the PCI of the first cell itself) (e.g., when a conflict between the first PCI and the PCI of another cell near the first cell is determined); and

[0073] means for instructing the IAB node to activate a second cell having the new PCI using the first DU of the IAB node.

[0074] Optionally, the second cell is activated while the first cell is still active (i.e., the first cell having the first PCI and the second cell having the second different and non-conflicting PCI are activated simultaneously). In some examples, wherein the user equipment is initially connected to the IAB donor node via a radio link in the first cell, the IAB donor node may also include:

[0075] means for triggering an intra-DU handover of the user equipment from the first cell to the second cell.

[0076] Optionally, the IAB donor node further includes:

[0077] Means for deactivating said first cell.

[0078] According to an eighth aspect of the present invention, there is provided an integrated access and backhaul (IAB) donor node, comprising a central unit (CU), the CU being configured to control an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (DU) of an IAB node of the IAB topology, the IAB donor node comprising:

[0079] means for determining a conflict between a physical cell identity (PCI) of the first cell and a PCI of another cell in the vicinity of the first cell;

[0080] means for obtaining a new PCI that does not cause a conflict with the PCI of another cell near the first cell (or the PCI of the first cell itself) (e.g., when a conflict between the first PCI and the PCI of another cell near the first cell is determined); and

[0081] means for instructing the IAB node to activate a second cell having the new PCI using a second DU of the IAB node.

[0082] Optionally, the second cell is activated while the first cell is still active (i.e., the first cell having the first PCI and the second cell having the second different and non-conflicting PCI are activated simultaneously). In some examples, wherein the user equipment is initially connected to the IAB donor node via a radio link in the first cell, the IAB donor node may also include:

[0083] A means for triggering an inter-DU handover of the user equipment from the first cell to the second cell.

[0084] Optionally, the IAB donor node further includes:

[0085] Means for deactivating said first cell.

[0086] Optionally, the IAB donor node further includes:

[0087] Means for deactivating said first DU.

[0088] According to a ninth aspect of the present invention, there is provided an integrated access and backhaul (IAB) donor node, comprising a target donor CU, the CU controlling a target IAB topology, the IAB donor node comprising:

[0089] means for receiving, from a source donor CU controlling a source IAB donor node of a source IAB topology, a node migration request for migrating an IAB node of the source IAB topology, the IAB node comprising a first distributed unit (DU) having established a first cell having a first physical cell identity (PCI);

[0090] means for obtaining a new PCI that does not cause a conflict with the PCI of another cell near the first cell (or the PCI of the first cell itself) (e.g., when a conflict between the first PCI and the PCI of another cell near the first cell is determined); and

[0091] The second DU of the IAB node for instructing migration of the source IAB topology establishes means for a second cell having the new PCI.

[0092] Optionally, the second cell is activated while the first cell is still active (ie, the first cell having the first PCI and the second cell having the second different and non-conflicting PCI are activated simultaneously). Optionally, the IAB donor node further includes:

[0093] A component configured to instruct the IAB node to deactivate the first cell.

[0094] Optionally, the IAB donor node further includes:

[0095] A component for instructing the IAB node to deactivate the first DU.

[0096] According to a tenth aspect of the present invention, there is provided a computer program comprising instructions, which, when the program is executed by a computer, cause the computer to execute the method according to the first to fifth aspects.

[0097] According to an eleventh aspect of the present invention, there is provided a computer readable medium carrying the computer program according to the tenth aspect.

[0098] The methods, devices, computer programs, and computer-readable media according to various aspects of the above-mentioned aspects may be considered to relate to a method for dynamic PCI change (and a device for dynamic PCI change), in the sense that the method may be performed continuously so that a new cell with a new PCI is activated in response to another cell entering the vicinity of an initial cell (the initial cell and the cell entering the vicinity are determined to have conflicting PCIs). In addition, the methods, devices, computer programs, and computer-readable media according to various aspects of the above-mentioned aspects may be considered to relate to a method for smooth PCI change (and a device for smooth PCI change), in the sense that a UE being served by the initial cell does not experience service interruption during the method.

[0099] Further exemplary features of the invention are described in the further independent and dependent claims.

[0100] Any feature in one aspect of the invention may be applied to other aspects of the invention in any appropriate combination. In particular, method aspects may be applied to apparatus / device / unit aspects, and vice versa.

[0101] In addition, features implemented in hardware may be implemented in software, and vice versa. Any reference to software features and hardware features herein should be interpreted accordingly. For example, according to other aspects of the present invention, there is provided a computer program including instructions and a computer-readable storage medium carrying the computer program, which instructions, when executed by a processing unit, cause the processing unit to perform any of the above aspects or examples of the method.

[0102] It should also be understood that specific combinations of the various features described and defined in any aspect of the invention may be independently implemented and / or provided and / or used. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Various aspects of the invention will now be described, by way of example only, and with reference to the following drawings, in which:

[0104] Figure 1 is a schematic diagram illustrating an exemplary communication system in which the present invention may be implemented according to one or more embodiments;

[0105] Figure 2 A and Figure 2 b schematically illustrates a stack of some protocol layers involved in IAB operation;

[0106] Figure 3 is a schematic diagram illustrating the format of a BAP protocol data unit (PDU) or packet;

[0107] Figure 4 is a schematic diagram illustrating an example of an IAB communication system (or IAB network system) in which the present invention may be implemented according to one or more embodiments;

[0108] Figure 5 is a schematic diagram illustrating another example of an IAB communication system (or IAB network system) in which the present invention may be implemented according to one or more embodiments;

[0109] Figure 6 is a schematic diagram illustrating another example of an IAB communication system (or IAB network system) in which the present invention may be implemented according to one or more embodiments;

[0110] Figure 7a is a schematic diagram illustrating an example of an IAB node architecture that enables smooth intra-CU PCI changes without service interruption for UEs served by the IAB node;

[0111] Figure 7b is a schematic diagram illustrating an example of an IAB node architecture that enables smooth intra-CU PCI change or smooth inter-CU PCI change without service interruption for UEs served by the IAB node;

[0112] Figure 8 is a flow chart of an example of steps to perform an intra-CU PCI change procedure to change the PCI of one or several cells controlled by an IAB node without service interruption for served UEs;

[0113] Fig. 9 is a flow chart of an example of steps to perform an inter-CU PCI change procedure to change the PCI of one or several cells controlled by an IAB node without service interruption for served UEs;

[0114] Fig.10a is a schematic diagram illustrating an example of a base station or RAN node architecture that enables smooth intra-CU PCI changes without service disruption for UEs served by the RAN node;

[0115] Fig.10b is a schematic diagram illustrating another example of a base station or RAN node architecture that enables smooth intra-CU PCI change or inter-CU PCI change without service interruption for UEs served by the RAN node;

[0116] Fig.11a is a flowchart of an example method of a process for performing activation of a logical DU and / or (one or more than one) cells according to an embodiment of the present invention;

[0117] Fig.11b is a flow chart of an example method of a process for setting a logical DU;

[0118] Fig.11c is a flow chart of an example method of a process for removing a logical DU;

[0119] Fig.12a is a flow chart of an example method of a process used by a RAN node CU to report new usage of (one or more than one) PCI values ​​to another RAN node CU;

[0120] Figure 12b is a flow chart of an example method of a process used by a RAN node CU to report a new use of (one or more than one) PCI value to a core network;

[0121] Fig.12c is a flow chart of an example method of a process used by a core network to indicate a list of (one or more than one) PCI values ​​that a RAN node CU may use;

[0122] Fig.13 is a schematic diagram of a wireless communication device according to one or more embodiments of the present invention;

[0123] Fig.14 is a flow chart illustrating an example method for managing changes of PCI in one or several cells at a CU of a base station according to one or more embodiments of the present invention;

[0124] Fig.15 is a flowchart of another exemplary method for managing changes of PCI in one or several cells at a CU of a base station according to one or more embodiments of the present invention;

[0125] Fig.16 is a flow chart of an example method for managing migration of an IAB node including a change of PCI in one or several cells according to one or more embodiments of the present invention. DETAILED DESCRIPTION

[0126] Figure 1 An example communication system 100 is illustrated in which the present invention may be implemented in accordance with one or more embodiments.

[0127] As depicted, system 100 is a wireless communication system, in particular a mobile radio communication system such as a fifth generation (5G) new air interface (NR) system including a wireless integrated access and backhaul network supporting a mobile IAB node. Although embodiments and examples of embodiments of the present invention will be described for a 5G NR system in the following description, it will be understood that the present invention is not intended to be limited to a 5G NR system and may be used in any wireless communication system having a mobile base station.

[0128] System 100 includes multiple UEs (user equipment) 132, 133, 131 and 134, a remote core network 110, a main base station 120 and two integrated access and backhaul (IAB) stations or IAB nodes 121 and 122 (hereinafter also referred to as IAB nodes), and a mobile integrated access and backhaul (IAB) station 123 mounted on a vehicle 105.

[0129] The primary base station 120 (also referred to as the IAB donor 120) is connected to the core network 110 via a wired link 101 (preferably an optical fiber or any other wired component). In embodiments and examples of embodiments of the present invention, as defined in the 3GPP TS 38.300 V17.0.0 specification document, the IAB donor 120 is a 5G NR (referred to as a gNB) with additional functions to support IAB features.

[0130] In order to extend the network coverage of the IAB donor 120 and reach the remote UEs 132, 133 and 131, the operator installs IAB stations 121 and 122 (also referred to as IAB nodes 121 and 122). By acting as relay nodes between the IAB donor 120 and the UEs 132 and 133, the IAB nodes 121 and 122 allow to overcome the accessibility issues caused by the presence of the building 108, which is an obstacle for the propagation of radio waves and therefore for direct attachment and further communication between the UE and the IAB donor 120. This is especially true when the communication between the IAB donor 120 and the UEs 132 and 133 operates at millimeter wave frequencies that are highly sensitive to shadowing phenomena.

[0131] The IAB donor 120 also serves the UE 134 , which is directly connected to the IAB donor 120 .

[0132] The mobile IAB station 123 (also referred to as a mobile IAB node (or mIAB node 123)) is an IAB node mounted on the vehicle 105 and also provides network coverage and capacity extension, allowing the IAB donor 120 to reach onboard remote UEs (such as remote UE 135), as well as surrounding UEs or UEs near the IAB node 123 (such as remote UE 136).

[0133] IAB donor 120 and IAB nodes 121 and 122 thus form a backhaul network or IAB network or IAB topology that accommodates UEs 132, 133, 131, 134, 135, and 136. The terms IAB network and IAB topology will be used interchangeably hereinafter.

[0134] The specification of Integrated Access and Backhaul (IAB) expands on several 3GPP standard documents, including:

[0135] -TS 38.300 RAN Architecture (V17.0.0),

[0136] -TS 38.321 MAC protocol (V17.0.0),

[0137] -TS 38.331 Radio Resource Control (RRC) Protocol (V17.0.0),

[0138] -TS 38.340 Backhaul Adaptation Protocol Layer (V17.0.0),

[0139] -TS 38.401 RAN architecture (V17.0.0),

[0140] -TS 38.473F1 application protocol (V17.0.0).

[0141] Since the IAB donor 120 and the IAB nodes 121, 122, and 123 are connected to the UEs 134, 131, 132, 133, 135, and 136, respectively, they are considered as access IAB nodes for the UEs to which they are respectively connected.

[0142] The IAB donor 120 is a logical node that provides NR-based wireless backhaul and consists of a central unit (CU or gNB-CU functionality) and connected (one or more) donor distributed units (DU or gNB-DU functionality). The IAB donor CU or donor CU (hereinafter also referred to as IAB donor CU) hosts higher layer protocols (such as PDCP (Packet Data Convergence Protocol) and RRC (Radio Resource Control) protocols, etc.) for controlling the operation of one or more DUs, and one or more IAB donor DUs or donor DUs (hereinafter also referred to as IAB donor DUs) each include lower layer protocols such as RLC, MAC and physical layer protocols. The IAB donor CU or donor CU and the IAB donor DU or donor DU can be located remote from each other, or can be located in the same physical device. The gNB-DU functionality is defined in 3GPP TS 38.401. Its purpose is as discussed below Figure 2 As shown, the NR access interface towards the UE and the next-hop IAB node is terminated, and the F1 protocol towards the IAB donor gNB-CU function is terminated.

[0143] The IAB nodes that can serve multiple radio sectors are connected via one or more hop wireless backhaul through intermediate IAB nodes to the IAB donor 120. They form a directed acyclic graph (DAG) topology with the IAB donor at the root.

[0144] The IAB node consists of an IAB-DU and an IAB-MT (IAB Mobile Terminal). The gNB-DU functionality on the IAB node is also referred to as the IAB-DU and allows downstream (towards the UE) connectivity to the next hop IAB. The IAB-MT functionality includes, for example, physical layer, layer 2, RRC, and non-access stratum (NAS) functionality to connect to the gNB-DU of the upstream IAB node, including the IAB donor 120, in this case, to the IAB donor gNB-DU and therefore to the core network 110 (e.g. for initialization, registration, and configuration).

[0145] In the DAG topology, the neighbor nodes on the IAB-DU interface are called child nodes, and the neighbor nodes on the IAB-MT interface are called parent nodes. The direction toward the child nodes is also called downstream, while the direction toward the parent node is called upstream.

[0146] The IAB donor 120 performs centralized resource, topology and routing management for the entire IAB topology, including configuring the IAB nodes according to the network topology, for example, to perform appropriate routing of data packets.

[0147] exist Figure 1 In the example of FIG. 1 , the DU parts of the IAB donor 120, IAB nodes 121, 122, and mobile IAB node 123 control cells 140, 141, 142, and 143, respectively. The coverage of different cells creates some overlapping areas, in which the UE can detect signal synchronization blocks (SSBs) from different DUs (be they DU parts of IAB nodes, IAB donors, mobile IAB nodes, or legacy base stations). The physical cell identity (PCI) value transmitted in each SSB helps the UE to distinguish between cells. The PCI planning algorithm aims to avoid PCI conflicts (i.e., reusing the same PCI value for neighboring cells) and PCI confusion (i.e., interference introduced by the PCI values ​​of neighboring cells).

[0148] In a cellular network, PCI values ​​can be assigned in a centralized or distributed manner. When using centralized assignment, the Operations Administration and Maintenance (OAM) system, which has complete knowledge and control of the PCI plan, will instruct the base station to use a dedicated PCI for each cell controlled by the base station. When using a distributed solution, the OAM system assigns a list of possible PCIs to the base station, but the final selection of the PCI is made by the base station itself. The base station can request a report sent by the UE or by other base stations in the neighborhood to know which PCIs have been used. The base station will then randomly select a PCI value from the remaining values ​​in the list of possible PCIs provided by the OAM system.

[0149] The CU of the base station sets the PCI for each DU in the (one or more than one) DU of the base station (the CU may control several DUs). Similarly, in the IAB topology, the IAB donor CU sets the PCI for each cell in the IAB topology it controls. The IAB donor CU shall indicate to each donor DU and to each DU of an IAB node or mobile IAB node the PCI to be used for the cell or cells controlled by the DU.

[0150] Figure 2 A and Figure 2 FIG. 2 schematically illustrates a stack of some protocol layers involved in IAB operation.

[0151] The F1 interface supports the exchange of signaling information between endpoints and the transmission of data to each endpoint. From a logical point of view, the F1 interface is a point-to-point interface between endpoints.

[0152] In 5G NR, F1-C is a functional interface in the control plane (CP) between the IAB donor CU and the IAB node DU (e.g., of IAB node 2) and between the IAB donor CU and the IAB donor DU. F1-U is a functional interface in the user plane (UP) for the same unit. F1-C and F1-U are composed of Figure 2 212 in a. In this example, F1-U and F1-C are carried by two return hops (from IAB donor to IAB node 1, and then from IAB node 1 to IAB node 2).

[0153] In the user plane, the block 210 at the IAB donor CU and the IAB node DU refers to the GTP-U layer, and the block 211 refers to the UDP layer. GTP-U stands for the GPRS Tunneling Protocol User Plane. The GTP-U tunnel is used to carry encapsulated PDUs and signaling messages between a given pair of GTP-U tunnel endpoints (refer to 3GPP TS29.281 for more details), here the block 210 at the IAB donor CU and the IAB node DU. The well-known User Datagram Protocol (UDP) is a transport layer protocol that provides best-effort datagram services and is suitable for use with the IP protocol.

[0154] In the control plane, box 210 indicates the F1AP (F1 Application Protocol) layer, and box 211 indicates the SCTP (Stream Control Transmission Protocol) layer. The F1 Application Protocol (as defined in 3GPP TS 38.473 and TS 38.401) provides signaling services between the IAB donor CU and the IAB node DU, or UE association services. These services are, for example, initialization, configuration, etc. The well-known SCTP layer provides reliable in-order transmission of messages with congestion control.

[0155] F1-U and F1-C rely on the IP transport layer between the IAB Donor CU and the IAB Node DU as defined in 3GPP TS 38.401.

[0156] When the IAB donor CU is remote from the IAB donor DU, or is locally in a virtual instantiation where the IAB donor CU and the IAB donor DU are on the same physical machine, the transmission between the IAB donor DU and the IAB donor CU also uses the IP transport layer over various media (e.g., wire or optical fiber). The IAB-specific transmission between the IAB donor CU and the IAB donor DU is specified in 3GPP TS 38.401.

[0157] L1 and L2 on the diagram represent the transport layer and physical layer respectively, appropriate to the medium in use.

[0158] The IP layer can also be used for non-F1 traffic, such as operations, management, and maintenance traffic.

[0159] Over the wireless backhaul, the IP layer itself is carried over the Backhaul Adaptation Protocol (BAP) sublayer, which enables routing over multiple hops. The BAP sublayer is specified in TS 38.340.

[0160] The IP traffic of the IAB-DU is routed through the wireless backhaul via the BAP sublayer. In the downstream direction, the upper layer packets are encapsulated by the BAP sublayer at the IAB donor DU, thereby forming a BAP packet or packet data unit (PDU) or data packet. The BAP packet is routed by the BAP layer or entity of the intermediate IAB node (if present) (and the corresponding BAP entity in the IAB-DU and IAB-MT). The BAP packet is finally decapsulated by the BAP sublayer at the destination IAB node (if the upper layer packets in the BAP packet are intended for the UE, the destination IAB node may be an access IAB node).

[0161] In the upstream direction, the upper layer packets are encapsulated by the BAP sublayer at the initiator IAB node (if the upper layer packets come from the UE, the initiator IAB node can be the access IAB node), thereby forming a BAP packet or data unit (PDU) or data packet. The BAP packet is routed by the BAP layer (and the corresponding BAP entity in IAB-DU and IAB-MT) of the intermediate IAB node (if any). The BAP packet is finally decapsulated by the BAP sublayer at the IAB donor DU.

[0162] At the BAP sublayer, packets are routed based on a BAP Routing ID, which is carried in the BAP header of the BAP packet and set by the initiator IAB node (eg, a network node in the IAB network that generates the BAP packet) or the BAP sublayer that transmits the IAB Donor DU. Figure 3 The format of an example BAP data protocol data unit (PDU) or packet 300 is specified in paragraph 6.2 of the standardized version of 3GPP TS 38.340 version 17.0.0.

[0163] Header 30 includes fields 301 to 306. Field 301 (referred to as the D / C field) is a Boolean value indicating whether the corresponding BAP packet is a BAP data packet or a BAP control packet. Fields 302 to 304 are 1-bit reserved fields, preferably set to 0 (ignored by the receiver).

[0164] Fields 305 and 306 together indicate the BAP routing ID of the BAP packet. The BAP address field 305 (also called the DESTINATION field) is located in the leftmost 10 bits, while the BAP path identification field 306 (also called the PATH field) is located in the rightmost 10 bits.

[0165] Field 305 carries the BAP address (i.e., on the BAP sublayer) of the destination IAB node or IAB donor DU of the BAP packet. For routing purposes, each IAB node and IAB donor DU is configured with a specified BAP address (either by the IAB donor CU that controls the IAB network or the topology to which the IAB nodes and IAB donor DUs belong). Field 306 carries the path ID that identifies the routing path that the BAP packet should follow in the IAB topology to reach that destination. Routing paths (including their path IDs) are configured in the same way that BAP addresses are configured.

[0166] When a packet reaches the BAP layer from an upper layer, a BAP header is added to the packet, and when the packet reaches its destination node, the BAP header is stripped by the BAP layer. The selection of a BAP routing ID for a packet is configured by the IAB donor CU.

[0167] For example, when a BAP packet is generated by an IAB node (i.e., by an IAB donor for downstream transmission or by an initiator IAB node for upstream transmission (which may be an access IAB node in the case where the upper layer packet is from a UE)), a BAP header with a BAP routing ID is constructed by the IAB node according to a configuration table defined in 3GPP TS38.340. The table is referred to as a downlink traffic to routing ID mapping configuration table in an IAB donor or an uplink traffic to routing ID mapping configuration table in an initiator IAB node. In an intermediate IAB node, the BAP header fields are already specified in the BAP packet for forwarding.

[0168] As described above, these configuration tables defining the BAP paths (and thus the routing policies and configuration of the IAB nodes taking into account the IAB network topology) are typically defined by the IAB Donor CU controlling the IAB network and transmitted to the IAB nodes to configure them.

[0169] To handle the transmission of messages over the 5G NR radio medium, three additional sublayers (RLC, MAC, and PHY) are implemented at each IAB node below the BAP sublayer. The RLC (Radio Link Control) sublayer is responsible for the segmentation or reconstruction of packets. The RLC sublayer is also responsible for requesting retransmission of lost packets. The RLC layer is further described in TS38.322. The MAC (Media Access Channel) protocol sublayer is responsible for selecting an available transport format for user data and for mapping logical channels to transport channels. MAC also handles part of the hybrid automatic repeat request scheme. The MAC layer is detailed in TS 38.321. On the transmitter side or transmitter side, MAC encapsulates data packets sent from RLC. MAC adds a header carrying information required for MAC functions. On the receiver side, MAC decapsulates data packets sent from PHY, removes its header, and passes the remaining data to RLC. The PHY sublayer provides an electrical interface to the transmission medium (air) by converting the information stream into a physical modulation signal and modulating the carrier frequency on the transmitter side. On the receiver side, the PHY sublayer converts the physical modulation signal back into an information stream. The PHY layer is described in TS 38.201, TS 38.211, TS 38.212, TS 38.213, TS 38.214.

[0170] To deliver messages towards the user plane or control plane, two other sublayers are used in the UE and IAB donor CU: the PDCP (Packet Data Convergence Protocol) sublayer, and the SDAP (Service Data Adaptation Protocol) sublayer for user plane communication or the RRC (Radio Resource Control) sublayer for control plane communication.

[0171] The PDCP sublayer handles IP header compression / decompression, encryption / decryption, and when necessary, integrity of data packets. Mandatory, packets are numbered on the transmitter side, and packets are reordered on the receiver side. The PDCP sublayer is described in 3GPP TS 38.323.

[0172] The SDAP sublayer 220 of the user plane handles the quality of service. The SDAP sublayer is described in TS 38.324. On the UE side, the SDAP sublayer exchanges payload data with the user's applications (voice, video, etc., not shown in the figure). On the IAB donor side, the SDAP sublayer exchanges data with the core network 110 (Internet traffic, cloud, etc.).

[0173] The RRC sublayer 220 for the control plane handles the configuration of the protocol entities of the user plane protocol stack. The RRC sublayer is described in TS38.331. The RRC sublayer is responsible for handling: broadcasting information required for UE to communicate with the cell; transmitting paging messages, managing connections, including establishing bearers; mobility functions; measurement configuration and reporting; device capabilities; and others.

[0174] The interface between nodes (for both CP and UP) using layers PDCP, RLC, MAC and PHY is called NR-Uu. This mainly involves the interface with the UE.

[0175] The interface between nodes (for both CP and UP) using layers BAP, RLC, MAC and PHY is called Backhaul RLC channel (BH RLC channel). This mainly concerns the interface between IAB nodes.

[0176] NR-Uu is the interface between the UE and the Radio Access Network, ie its access IAB node (for both CP and UP).

[0177] Figure 2 The b comes from 3GPP TS 38.300V17.0.0 and illustrates the protocol stack for RRC and NAS connections to support IAB-MT. The non-access stratum (NAS) protocol handles messages between the core network and the user equipment (here is the IAB node). The NAS protocol manages the establishment of communication sessions and maintains communication with the user equipment when the user equipment moves. 5G NAS is described in 3GPP TS24.501. The 5G core access and mobility management function (AMF) is a function within the core network that is used to receive all connection and session related information from the UE connected to the IAB node, and receive similar information from the IAB node. The AMF is only responsible for handling connection and mobility management tasks.

[0178] The IAB-MT establishes a signaling radio bearer SRB (a bearer carrying RRC and NAS messages) with the IAB donor CU. These SRBs are transmitted between the IAB-MT and its parent node(s) over the NR-Uu interface(s).

[0179] Figure 4 An example of a wireless communication system (or IAB network) 400 in which embodiments and examples of embodiments of the present invention may be implemented is illustrated. In one example implementation, the radio link between the IAB node and the IAB donor DU node (referred to as the BH radio link) operates on a millimeter wave band (i.e., above 30 GHz) that is highly sensitive to radio channel interference. The IAB network will also be referred to as an IAB topology or topology, and thus in this application, the terms IAB network and IAB topology and topology will be used interchangeably.

[0180] The IAB communication system is composed of two IAB networks or IAB topologies 4001 and 4002, each of which includes a set of IAB nodes (for example, the set may include multiple IAB nodes or at least one IAB node) and an IAB donor CU for controlling or managing multiple IAB nodes. The group of IAB nodes may include one or more IAB nodes, such as an initiator IAB node that generates a BAP packet and an intermediate or relay IAB node. The group of IAB nodes may also include one or more IAB donor DUs. Each IAB node communicates with at least one other IAB node via a wireless backhaul (BH) link.

[0181] although Figure 4 Two IAB topologies 4001 and 4002 are shown, but the present invention is not limited to the two IAB topologies 4001 and 4002 and may be implemented in an IAB communication system including more than two IAB topologies (where each topology includes a set of IAB nodes and an IAB donor CU as described above).

[0182] The IAB topology 4001 includes an IAB donor CU 401 (in Figure 4 ), its associated IAB donor DU, and IAB donor DU 403 (in Figure 4 Donor1-DU1) and IAB donor DU 404 (in Figure 4 4), and multiple IAB nodes 410, 420, 430, and 460 similar to IAB nodes 121 and 122, and an IAB node 470 similar to mobile IAB node 123. All IABs may be access nodes that serve UEs such as UE 480 served by mobile IAB node 470. IAB topology 4001 is transparent to UE 480 connected to donor CU 401 through DU portion or unit mDU 472 of mobile IAB node 470.

[0183] The IAB topology 4002 includes an IAB donor CU 402 (in Figure 4 ) and its associated IAB donor DU 405 (identified as Donor2-CU in Figure 4 1), and multiple IAB nodes 440 and 450 similar to IAB nodes 121 and 122. IAB network 400 may provide network path diversity through several IAB donor DUs and different IAB networks or topologies.

[0184] As described above, each IAB node includes a mobile terminal (MT) portion or unit controlled and configured by the IAB donor CU using RRC messaging as defined in 3GPP TS 38.331, and a distributed unit (DU) portion controlled and configured by the IAB donor CU using F1-AP messaging as defined in 3GPP TS38.473. For example, IAB node 410 includes an MT portion or unit 411 and a DU portion or unit 412.

[0185] The wired backhaul IP network interconnects IAB donor CUs 401 and 402 and IAB donor DUs 403, 404, and 405 through a wired link 406. For example, the wired link consists of (one or more than one) optical fiber cables.

[0186] IAB donor CU 401 , IAB donor DUs 403 and 404 , IAB nodes 410 , 420 , 430 , 460 , 470 , and IAB node 480 are part of the same IAB network or IAB topology 4001 that is controlled (eg, configured and / or managed) by IAB donor CU 401 .

[0187] IAB donor CU 402 , IAB donor DU 405 , and IAB nodes 440 and 450 are part of the same IAB network or IAB topology 4002 that is configured and managed or controlled by IAB donor CU 402 .

[0188] All donor DUs 403, 404, 405 and the DUs of IAB nodes 412, 422, 462, 472, 442, 452 handle one or several cells not shown in the figure.

[0189] In this example, the mobile IAB node 470 is first singly connected to the IAB node 460 via the link 4060. Assuming that the mobile IAB node 470 is moving in the direction of the IAB node 430, the mobile IAB node 470 may have the opportunity to be dually connected to the IAB node 430 as the second parent IAB node via the link 4030. Instead of dual connectivity, the mobile IAB node 470 may be migrated to the IAB node 430 by the donor CU 401, and then the mobile IAB node 470 will be singly connected to the IAB node 430 via the link 4030, and the mobile IAB node 470 will no longer be connected to the IAB node 460.

[0190] When moving in the direction of IAB node 430 and also in the direction of IAB node 410, the PCI used by mobile IAB node 470 for one of its cells may conflict with one or several PCI values ​​used in (for example) IAB node 410. Donor CU 401 may detect this potential PCI conflict based on the knowledge of the proximity of mobile IAB node 470 to the cell(s) controlled by IAB node 410 (i.e., based on the new connection to IAB node 430). Therefore, according to an embodiment of the present invention, donor CU 401 may trigger the use of Figure 8 The process used for the PCI change (PCI change within CU).

[0191] As an alternative to detecting PCI conflicts, the donor CU 401 may use Figure 12b The process described above sends a notification to the core network (not shown) of the new location of the cell(s) controlled by the mobile IAB node 470. In response, the core network may indicate to the donor CU 401 the potential PCI conflict and an update of the PCI value or list of PCI values ​​that may be assigned to the cell(s) controlled by the mobile IAB node 470. The core network's response may be accomplished by utilizing Fig.12c The process described is carried out.

[0192] Figure 5 Another example of an IAB communication system (or an IAB network system) 500 in which embodiments and examples of the embodiments of the present invention can be implemented is illustrated. Figure 5 and Figure 4 The system 400 described in FIG. 1 is similar to the system 400 described in FIG. 1 in that there are two IAB topologies 5001 and 5002. The IAB topology 5001 includes an IAB donor CU 501 (in Figure 5 ), its associated IAB donor DU, and IAB donor DU 503 (in Figure 5 Donor1-DU1) and IAB donor DU 504 (in Figure 5 1-DU2), and multiple IAB nodes 510, 520, 530, and 560 similar to IAB nodes 121 and 122. The IAB topology 5002 includes an IAB donor CU 502 (in Figure 5 ) and its associated IAB donor DU 505 (identified as Donor2-CU in Figure 51), and multiple IAB nodes 540 and 550 similar to IAB nodes 121 and 122, and an IAB node 570 similar to mobile IAB node 123. The IAB topology 5002 is transparent to the UE 580 connected to the donor CU 502 through the DU portion or unit mDU 572 of the mobile IAB node 570.

[0193] Figure 5 Example Figure 4 IAB node 470 (ie, Figure 5 The migration result of the IAB node 570 in the IAB node 470 (ie, Figure 5 IAB node 570 in FIG. 5 is now connected to IAB node 430 (ie, Figure 5 ), and is no longer connected to IAB node 460 (ie, Figure 5 IAB node 560 in.

[0194] When the mobile IAB node is moving in the direction of the IAB topology 5002 and the IAB node 550, several scenarios are possible according to the IAB framework.

[0195] As a first scenario, as described in TS 38.401 V17.0.0 Section 8.17.2.1, a topology redundancy procedure may be applied, in which dual connectivity is established for an IAB node 570 having two parent IAB nodes 530 and 550 belonging to two different IAB topologies.

[0196] When the IAB node 570 is initially connected to a single IAB topology (e.g., IAB topology 4001), as defined in 3GPP TS38.300, the MT section or unit mMT 571 of the IAB node 570 periodically performs a cell search procedure, thereby attempting to detect the PSS (primary synchronization signal) and the SSS (secondary synchronization signal). The IAB node can report the presence of a new cell managed by, for example, the IAB node 550 to its donor CU 501 through a measurement report including the PCI of the cell as calculated using the PSS and PSS signals. Based on the analysis of the measurement report, the donor CU 501 can request the donor CU 502 to establish dual connectivity for the IAB node 570 with an additional connection through the IAB node 550. The donor CU 502 can accept the request and proceed with the connection of the IAB node 570 according to the process described in Section 10.2 of TS37.340 V17.0.0. As a result, the IAB node 570, which still belongs to the IAB topology 5001, is now also connected to the IAB node 550, which belongs to the IAB topology 5002, and the IAB node 570 may be referred to as a boundary node between the IAB topology 5001 and the IAB topology 5002. In practice, the IAB node 570 retains its F1 connection and RRC connection to the donor CU 501 (which may be referred to as an F1-terminating IAB-donor-CU), and the IAB node 570 has another RRC connection to the donor CU 502 (which may be referred to as a non-F1-terminating IAB-donor-CU).

[0197] Since the IAB node or border node 570 is part of the IAB topology 5001 (from the perspective of the F1 connection), the IAB node or border node 570 is controlled (eg, configured and / or managed) by the IAB donor CU 501 of the IAB topology 5001 .

[0198] When moving in the direction of IAB node 550 and also in the direction of IAB node 540, the PCI used by mobile IAB node 570 for one of its cells may conflict with the PCI value(s) used in IAB node 550 or 540. Fig.12a 501 is informed of the PCI value set in the IAB topology 5002, the donor CU 501 can detect a potential PCI conflict after a new connection of the mobile IAB node 570 in the cell controlled by the IAB node 550. Therefore, according to an embodiment of the present invention, the donor CU 501 can trigger the use of Figure 8 The process used for the PCI change (PCI change within CU).

[0199] As Figure 5 In the second scenario, the BH link or BH radio link 5030 may also experience a radio link defect due to some unexpected interference or shadowing phenomenon. Due to such reasons, the IAB node 570 may lose the connection with the IAB node 530 and declare a radio link failure (RLF) for the BH link 5030. Then, the IAB node 570 will try to re-establish the connection with the same or different parent IAB node (or donor DU). Thus, the IAB node 570 may try to join the IAB topology 5002 managed by the IAB donor CU 502 with the connection through the new parent IAB node 550 using the BH link 5050. In this case, as described in Section 8.17.4 of TS 38.401 V17.0.0, the inter-CU backhaul RLF recovery procedure can be applied, which enables the IAB node to be restored to another parent node under a different IAB donor CU when the IAB-MT of the IAB node declares a backhaul RLF. In such a process, the donor CU 502 sends a request to the donor CU 501 to retrieve the context of the IAB node 570. Based on the response from the donor CU 501, the donor CU 502 may accept the connection of the IAB node 570, and the IAB node 570 becomes a boundary node that still belongs to the IAB topology 5001. In this case, the IAB node 570 retains the F1 connection to the donor CU 501 (which may be referred to as an F1-terminating IAB donor CU), and the IAB node 570 has an RRC connection to the donor CU 502 (which may be referred to as a non-F1-terminating IAB donor CU).

[0200] As Figure 5 In the third scenario, an IAB node 570 that is only connected to a parent IAB node 530 can partially migrate toward an IAB topology 5002, which means that its RRC connection is migrated from an old parent node to a new parent node, where the old parent node and the new parent node are served by different IAB donor CUs. In fact, based on the measurement report provided by the IAB node 570, the donor CU 501 can detect that the IAB node 570 will have a better connection through a cell managed by an IAB node 550 belonging to the IAB topology 5002. Then, the donor CU 501 can trigger the IAB inter-CU topology adaptation process described in Section 8.17.3.1 of TS 38.401V17.0.0. In this process, the donor CU 501 sends a handover request for the IAB node 570 together with information for the donor CU 502 to establish an RRC connection to the IAB node 570. Based on this information, using the F1 connection to the donor CU 501 and the RRC connection to the donor CU 502 , the donor CU 502 can accept the handover request and proceed with the admission of the IAB node 570 , which becomes a boundary node still belonging to the IAB topology 5001 .

[0201] In this third scenario, IAB topology 5001 may be referred to as a source IAB network or source IAB topology, and topology 5002 may be referred to as a target IAB network or target IAB topology. In addition, donor CU 501 may be referred to as a source IAB donor CU or source donor CU, and donor CU 502 may be referred to as a target IAB donor CU or target donor CU.

[0202] In the second and third scenarios, when moving in the direction of IAB node 550 and also in the direction of IAB node 540, the PCI used by the mobile IAB node for one of its cells may conflict with the PCI value(s) used in IAB node 550 or 540. Assume (e.g., using Fig.12a 501 is informed of the PCI value set in the IAB topology 5002, the donor CU 501 can detect a potential PCI conflict after a new connection of the mobile IAB node 570 in the cell controlled by the IAB node 550. Therefore, according to an embodiment of the present invention, the donor CU 501 can trigger the use of Figure 8 The process used for the PCI change (PCI change within CU).

[0203] To detect potential PCI conflicts in the three scenarios above, the donor CU 501 may use Figure 12b The process described in 5 sends a notification to the core network (not shown) of the new location of the cell(s) controlled by the mobile IAB node 570. In response, the core network may indicate to the donor CU 501 the potential PCI conflict and an update of the PCI value or list of PCI values ​​that may be assigned to the cell(s) controlled by the mobile IAB node 570. The core network's response may be accomplished by utilizing Fig.12c The process described is carried out.

[0204] In all three scenarios described above, the UE 580 is still connected to the donor CU 501 through the DU portion or unit mDU 572 of the mobile IAB node 570. In the case where the IAB node 570 has several (one or more than one) child IAB nodes, such child IAB nodes still belong to the IAB topology 5001, and the child IAB nodes are still fully controlled by the donor CU 501 (through the F1 connection and the RRC connection).

[0205] Figure 6 Another example of an IAB communication system (or an IAB network system) 600 in which embodiments and examples of the embodiments of the present invention can be implemented is illustrated. Figure 6 and Figure 5The system 500 described in FIG. 1 is similar to the system 500 described in FIG. 1 in that there are two IAB topologies 6001 and 6002. The IAB topology 6001 includes an IAB donor CU 601 (which is Figure 6 ), its associated IAB donor DU, and IAB donor DU 603 (identified as Donor1-CU in Figure 6 ) and IAB donor DU 604 (identified as Donor1-DU1 in Figure 6 6002 includes an IAB donor CU 602 (identified as Donor1-DU2 in FIG. 1 ), and multiple IAB nodes 610, 620, 630, and 660 similar to IAB nodes 121 and 122. Figure 6 ) and its associated IAB donor DU 605 (identified as Donor2-CU in Figure 6 The IAB topology 6002 includes a plurality of IAB nodes 640 and 650 similar to the IAB nodes 121 and 122 and an IAB node 670 similar to the mobile IAB node 123. The IAB topology 6002 is transparent to the UE 680 connected to the donor CU 602 via the DU portion or unit mDU672 of the mobile IAB node 670.

[0206] Figure 6 Example Figure 5 IAB node 570 (ie, Figure 6 As a result of the complete migration of the IAB node 670 in FIG. 5, the IAB node 570 now completely belongs to Figure 5 IAB topology 5002 in (ie, Figure 6 IAB topology in 6002).

[0207] (refer to Figure 5 The) partial migration allows IAB-MT part or unit mMT ( Figure 5 571) quickly migrates to the target IAB donor CU (ie, Figure 5 502 in the donor CU) and quickly switches back to the source IAB donor CU (ie, Figure 5 Thus, partial migration may be advantageously used when inter-donor migration is only required temporarily (such as during peak traffic hours, etc.), or when a transient RLF on a BH link is detected.

[0208] In the context of full migration, both the IAB-MT portion or unit mMT 671 and the IAB-DU portion or unit mDU 672 of the IAB node 670 are migrated to the target donor CU 602. Full migration is suitable for mobile IAB nodes that are mobile and may cross several IAB topologies during their journey.

[0209] The complete migration of mobile IAB node 670 is also an opportunity for donor CU 602 to change the PCI value used by mobile IAB node 670 in the event of a potential conflict. Fig. 9 (Inter-CU PCI Change) is used to describe the process used for PCI change associated with the full migration of the mobile IAB node. In the full migration of the IAB node 670, the served UE such as UE 680 also migrates from the source donor CU 601 to the target donor CU 602. This can be done through the handover process described in Section 9.2.3.2 of TS 38.300 V17.0.0 ( Fig. 9 UE migration is performed using the process described in .

[0210] Figure 7a An example of an IAB node architecture 700 is illustrated that enables smooth intra-CU PCI changes without service interruption for UEs served by the IAB node. Figure 8 The intra-CU PCI change process described is applicable to IAB nodes that are not fully migrating towards a new IAB donor CU.

[0211] Although the description of some examples of the present invention focuses on the PCI change for the mobile IAB node, the present invention does not exclude the application of the intra-CU PCI change process to the stationary IAB node. Thus, the IAB node 701 can be a mobile IAB node such as the mobile IAB node 470 (also 570, 670), or an IAB node such as the IAB node 460 (also 560, 660). The IAB node 701 includes an IAB-MT part or unit 710 and an IAB-DU part or unit 711.

[0212] Before the PCI is changed, UE 702 is, for example, in cell 731 and connected to a donor CU (not shown) via IAB-DU 711 using access link 721. IAB-DU 711 may control several other cells not shown in the figure. Upon detecting that the PCI of cell 731 may conflict with other PCIs near cell 731, the donor CU may trigger a Figure 8 In this process, a new cell 732 controlled by the IAB-DU 711 is activated, and on the new cell 732, the UE 702 can also use the access link 722 to connect to the donor CU through the IAB-DU 711.

[0213] In one example, a cell near cell 731 may correspond to a cell that is adjacent to cell 731 and covers a geographic area that may partially or completely overlap with the geographic area covered by cell 731. In another example, a cell near cell 731 may correspond to a cell that is not adjacent to cell 731 but is adjacent to a third cell (which is also adjacent to cell 731).

[0214] By the donor CU, for example, using reference Fig.11a The described process triggers the activation of the cell 732. During the activation process, the donor CU indicates to the IAB-DU 711 the PCI value to be used for the cell 732.

[0215] Still refer to Figure 8 Once the handover of a UE such as UE 702 from cell 731 to cell 732 is completed, cell 732 may be deactivated.

[0216] After detecting the completion of the UE handover, the donor CU uses the reference Fig.11a The described procedure triggers the deactivation of a cell.

[0217] Figure 7b Another example of an IAB node architecture 750 that enables smooth intra-CU PCI changes or smooth inter-CU PCI changes without service interruption for UEs served by the IAB node is illustrated. Figure 8 The described intra-CU PCI change process is applicable to IAB nodes that are not fully migrated. Fig. 9 The inter-CU PCI change process described is applicable to an IAB node that is completely migrating towards a different IAB donor CU.

[0218] Although the PCI change may be necessary only for mobile IAB nodes, the present invention does not exclude the application of the intra-CU PCI change process and the inter-CU PCI change process to stationary IAB nodes. Thus, the IAB node 751 may be a mobile IAB node such as the mobile IAB node 470 (also 570, 670), or an IAB node such as the IAB node 460 (also 560, 660). The IAB node 751 includes an IAB-MT part or unit 760, an IAB-DU1 part or unit 761, and an IAB-DU2 part or unit 762. Both IAB-DU1 and IAB-DU2 are logical DU entities that share the same hardware for the BAP, REC, and MAC layers. In one embodiment, they share the same physical layer (i.e., the same hardware resources), while in another embodiment, they rely on separate physical layers. In this example, IAB-DU1 761 controls cell 781 when activated, and IAB-DU2 762 controls cell 782 when activated. Both IAB-DU1 761 and IAB-DU2 762 may handle several other cells not shown in the figure.

[0219] When both logical DUs are active, only one logical DU is sufficient for IAB operation except at intra-CU PCI change, at inter-CU PCI change, or at full migration of PCI change without IAB node 751. For intra-CU PCI change, both logical DUs terminate the F1 interface with the same donor CU. For inter-CU PCI change, one of the logical DUs terminates the F1 interface with the source donor CU, while the other logical DU terminates the F1 interface with the target donor CU.

[0220] In case the processing load of the logical DU IAB-DU1 761 is high due to a large number of cells, Figure 7b The architecture of can be used for intra-CU PCI change. In this case, the processing load of IAB-DU1 761 can be reduced by activating the second logical DU IAB-DU2 762 during the PCI change phase.

[0221] In the case of intra-CU PCI change and prior to operation, UE 752 is, for example, in cell 781 and connected to a donor CU (not shown) via IAB-DU1 761 using access link 771. Upon detecting that the PCI of cell 781 may conflict with other PCIs in the vicinity of cell 781, the donor CU may trigger a PCI change procedure, where a logical DU IAB-DU2 762 is activated along with a new cell 782 on which UE 752 may also be connected to the donor CU via access link 772.

[0222] Utilized by the donor CU e.g. Fig.11a The described process triggers the activation of the logical DU IAB-DU2 762 together with the cell 782. During the activation process, the donor CU indicates to IAB-DU1 761 the PCI value to be used for the cell 782.

[0223] refer to Figure 8 According to the process described above, once the handover of a UE such as UE 752 from cell 781 to cell 782 is completed, cell 781 is deactivated.

[0224] After detecting the completion of the UE handover, the donor CU uses Fig.11c The described procedure triggers the deactivation of a cell.

[0225] When activating the logical DU IAB-DU2 762, the donor CU may activate as many cells as the number of cells controlled by the logical DU IAB-DU1 761. Then, all UEs connected through the logical DU IAB-DU1 are handed over via the cells controlled by the logical DU IAB-DU2 762. Once the handover of all UEs is completed, the donor CU deactivates the logical DU IAB-DU1 761 together with all the cells it is controlling.

[0226] After detecting the completion of the UE handover, the donor CU uses, for example, Fig.11c The described process triggers the deactivation of the logic DUIAB-DU1 761.

[0227] In the case of inter-CU PCI change and before operation, UE 752 is, for example, in cell 781 and connected to the source donor CU via logical DU IAB-DU1 761 using access link 771, while logical DU IAB-DU2 762 is deactivated. Fig. 9 During the PCI change process, the logical DU IAB-DU2 762 is activated and connected to the target donor CU, wherein the UE 752 can also connect to the target donor CU through the logical DU IAB-DU2 762 using the cell 782 and the access link 772 .

[0228] The activation of the logical DU IAB-DU2 762 can be triggered by the IAB node and then by utilizing Fig.11b The target donor CU can be set up by using Fig.11b The process described indicates the PCI value to be used for the cell(s) (such as cell 782) to be activated using the second logical DU.

[0229] Still refer to Fig. 9According to the process described above, once the handover of a UE such as UE 752 from cell 781 to cell 782 is completed, cell 781 is deactivated.

[0230] After detecting the completion of the UE handover, the source donor CU uses Fig.11a The described procedure triggers the deactivation of a cell.

[0231] When activating the logical DU IAB-DU2 762, the target donor CU may activate as many cells as the number of cells controlled by the logical DU IAB-DU1 761. Then, all UEs connected through the logical DU IAB-DU1 761 are handed over via the cells controlled by the logical DU IAB-DU2 762. Once the handover of all UEs is completed, the source donor CU deactivates the logical DU IAB-DU1 761 together with all the cells it is controlling.

[0232] After detecting the completion of the UE handover, the source donor CU, for example, Fig.11c The described process triggers the deactivation of the logical DU IAB-DU1 761 .

[0233] Figure 8 is a simplified flow chart 800 illustrating an example of steps to perform an intra-CU PCI change procedure to change the PCI of one or several cells controlled by an IAB node without service interruption for served UEs. Figure 8 based on Figure 7a or Figure 7b The architecture of the IAB node described in .

[0234] The figure shows a UE 801 such as UE 580, a donor CU 803 such as donor CU 501, and a core network (5GC) 802 such as core network 110. The figure also shows Figure 7a An IAB node such as the IAB node 701 of FIG. 8 (which is composed of an IAB-MT portion or unit 804 and an IAB-DU1 portion or unit 805), or Figure 7b 804, IAB-DU1 and IAB-DU2 are two logical DU entities that share the same hardware for BAP, RLC and MAC layers. In one embodiment, they share the same physical layer (i.e., the same hardware resources), while in another embodiment, they rely on separate physical layers.

[0235] At the beginning of the flow chart, the UE 801 is served by the IAB node through the cell controlled by IAB-DU1 805, and when using Figure 7b In the case of the architecture, the logical DU IAB-DU2 806 is inactive. User data in the downstream direction is provided by the 5GC 802 to the donor CU 803 via bearer 820, and then they are transmitted to the logical DU IAB-DU1 805 via backhaul bearer 821, and finally transmitted to the UE 801 via data radio bearer 822. User data in the upstream direction (not shown in the figure) is transmitted via similar bearers in the opposite direction.

[0236] After the donor CU 803 decides to change the PCI value for one or several cells controlled by the IAB node and has determined the new PCI value(s) to be used, the first step 811 corresponds to the activation of the cell(s) using the new PCI value(s). Figure 7a In the case of an architecture of , the (one or more) new cells are controlled by the logical DU IAB-DU1 805, or when using Figure 7b In the case of an architecture of , the (one or more) new cells are controlled by logical DU IAB-DU2 806. In this latter case, step 811 comprises the activation of logical DU IAB-DU2. In all cases, there may be as many created cells as the number of PCI values ​​to be changed, or as many cells as the number of cells controlled by logical DU IAB-DU1 805. For example, Fig.11a The described procedure is for activation of the logical DU IAB-DU2 806 and for activation of (one or more than one) cells.

[0237] The next step 812 is for the UE served by the IAB node to move from the cell controlled by the logical DU IAB-DU1 805 having the first PCI value to the cell controlled by the logical DU IAB-DU1 805 ( Figure 7a in the architecture) or by the logical DU IAB-DU2 806 ( Figure 7b The UE handover procedure corresponds to the procedure described in Section 8.2.1.2 of TS 38.401 V17.0.0.

[0238] In use Figure 7aIn the case of an IAB node of the architecture of FIG801, once the handover is completed for UE 801, user data in the downstream direction is transmitted by the core network 802 to the donor CU 803 through a bearer 820, and then they are transmitted to the logical DU IAB-DU1 805 through a backhaul bearer 821, and finally transmitted to UE 801 through a new data radio bearer 823 in the new cell. User data in the upstream direction (not shown in the figure) is transmitted through a similar bearer in the opposite direction.

[0239] In use Figure 7b In the case of an IAB node of the architecture of FIG801, once the handover is completed for UE 801, user data in the downstream direction is transmitted by the core network 802 to the donor CU 803 through a bearer 820, and then they are transmitted to the logical DU IAB-DU2 806 through a backhaul bearer 824, and finally transmitted to UE 801 through a data radio bearer 825 in the new cell. User data in the upstream direction (not shown in the figure) is transmitted through a similar bearer in the opposite direction.

[0240] At step 813, once the handover is completed for all UEs served in the cell with the first PCI, the cell may be deactivated. Fig.11a The described procedure may be used for cell deactivation.

[0241] In use Figure 7b In the case of an IAB node of an architecture of , when the handover is completed for all UEs served by the logical DU IAB-DU1 805, then the logical DU can be deactivated. Fig.11c The deactivation of (one or more than one) cells controlled by the logical DU IAB-DU1 805 may be performed simultaneously.

[0242] Fig. 9 is a simplified flow chart 900 illustrating an example of steps to perform an inter-CU PCI change procedure to change the PCI of one or several cells controlled by an IAB node without service interruption for served UEs. Fig. 9 based on Figure 7b The process may be part of a complete migration process for an IAB node which may be a mobile IAB node.

[0243] The figure shows a UE 901 such as UE 580, a source donor CU 903 such as donor CU 501, a target donor CU 907 such as donor CU 502, and a core network (5GC) 902 such as core network 110. The figure also shows an IAB node such as IAB node 751, which includes an IAB-MT part or unit 904, an IAB-DU1 part or unit 905, and an IAB-DU2 part or unit 906. IAB-DU1 and IAB-DU2 are two logical DU entities that share the same hardware for BAP, RLC and MAC layers. In one embodiment, they share the same physical layer (i.e., the same hardware resources), while in another embodiment, they rely on separate physical layers.

[0244] At the beginning of the flow chart, the UE 901 is served by the IAB node through the cell controlled by IAB-DU1 905, while the logical DU IAB-DU2 806 is inactive. User data in the downstream direction is provided by the 5GC 902 to the donor CU 903 through bearer 920, and then they are transmitted to the logical DU IAB-DU1 905 through backhaul bearer 921, and finally transmitted to the UE 901 through data radio bearer 922. User data in the uplink direction (not shown in the figure) is transmitted through similar bearers in the opposite direction.

[0245] The first step 911 corresponds to a partial migration of an IAB node, or to the establishment of dual connectivity of a mobile IAB node, or to RLF recovery of a mobile IAB node. After this step, the IAB node is a boundary node between a source IAB topology controlled by an IAB donor CU 903 and a target IAB topology controlled by a target donor CU 907.

[0246] In case of partial migration, the inter-IAB CU topology adaptation procedure described in TS 38.401 V17.0.0 Section 8.17.3.1 may be applied, after which the IAB node still belongs to the IAB topology controlled by the source donor CU 903 but has an RRC connection with the target donor CU 907 .

[0247] In case of dual connectivity setup, as described in TS 38.401 V17.0.0 section 8.17.2.1, a topology redundancy procedure may be applied, where dual connectivity is established for an IAB node having two parent IAB nodes belonging to two different IAB topologies.

[0248] In case of RLF recovery, as described in TS 38.401 V17.0.0 Section 8.17.4, the Inter-CU Backhaul RLF Recovery procedure may be applied, which enables the IAB node to be recovered to another parent node under a different IAB donor CU when its IAB-MT declares backhaul RLF.

[0249] Step 912 corresponds to traffic migration relying on the IAB transport migration management procedure specified in Section 8.5.2 of TS 38.423 V17.0.0. After this step, user data in the downlink direction is still delivered to the UE 901 via the backhaul bearer 923 in the target IAB topology controlled by the target donor CU 907. User data in the upstream direction (not shown in the figure) is transported via a similar bearer in the opposite direction.

[0250] Step 913 corresponds to the activation of the second logical DU IAB-DU2 906 in the IAB node, including the activation of one or several cells controlled by IAB-DU2 906. The activation may be triggered in the IAB node itself, for example, after the IAB node obtains an RRC connection with the target donor CU 907. Fig.11b 906. The target donor CU 907 receiving the setup request from IAB-DU2 906 will respond with a request to create (one or more) new cells controlled by IAB-DU2 906. There may be as many created cells as the number of cells controlled by the logical DU IAB-DU1 905. In addition, the IAB donor CU 907 may detect that the PCI value used in one or several cells controlled by IAB-DU1905 may conflict with (one or more) nearby PCI values. Thus, the IAB donor CU 907 will obtain (one or more) new PCI values ​​to be used for (one or more) cells to be controlled by IAB-DU2 906. In the case of a complete migration of the mobile IAB node, there will be as many created cells as the number of cells controlled by the logical DU IAB-DU1905. The IAB donor CU 907 will obtain the new PCI value(s) to be used for the cell(s) to be controlled by IAB-DU2 906. If the PCI value(s) used in the cell(s) controlled by IAB-DU1 905 conflict with the nearby PCI value(s), the conflict will be resolved (at step 915) when the full migration is completed.

[0251] To accomplish step 913, the target donor CU 907 utilizes, for example, Fig.12aAccording to the process described in , the source donor CU 903 is informed of the second logical DU IAB-DU2 906 and the activation of the cell(s) with the new PCI value(s).

[0252] After the activation of the second logical DU and (one or more) new cells in the IAB node (step 913), the next step 914 consists in the handover of the UE served by the IAB node from the cell controlled by the first logical DU mIAB-DU1 905 to the cell controlled by the second logical DU IAB-DU2 906. The UE handover is based on the procedure described in Section 9.2.3 of TS 38.300 V17.0.0. Step 914 may be triggered by the source donor CU 903 after receiving a notification of the activation of (one or more) cells in the second logical DU IAB-DU2 906 at the end of step 913. Alternatively, step 914 may be triggered when the source donor CU 903 receives a measurement report from the UE indicating that the UE receives a radio signal in the cell controlled by IAB-DU2 906.

[0253] Once the handover is completed for UE 901, user data in the downstream direction is transmitted by the core network 902 to the target donor CU 907 via bearer 924, and then they are transmitted to the logical DU IAB-DU2 906 via backhaul bearer 925, and finally transmitted to UE 901 via data radio bearer 926 in the new cell. User data in the upstream direction (not shown in the figure) is transmitted via similar bearers in the opposite direction.

[0254] Once handover is completed for all UEs served in a cell with a potentially conflicting PCI, the cell can be deactivated. Fig.11c The described procedure may be used for cell deactivation.

[0255] When the handover is completed for all UEs served by the logical DU IAB-DU1 905, the logical DU can then be deactivated. Fig.11c The deactivation of (one or more than one) cells controlled by the logical DU IAB-DU1 905 may be performed simultaneously.

[0256] Fig.10aAn example of a base station or RAN (Radio Access Network) node architecture 1000 is illustrated that enables smooth intra-CU PCI changes without service interruption for UEs served by the RAN node. In practice, the intra-CU PCI change procedure may also be applicable to RAN nodes such as gNBs that are not IAB nodes. For example, a PCI change may be required when the RAN node is moving, or at least when the DU part of the RAN node is moving. This may be the case in non-terrestrial networks where the DU part is embedded in a satellite or drone, for example.

[0257] Should Fig.10a The RAN node is shown divided into a CU part (RAN node CU) 1002 and a DU part (RAN node DU) 1001 connected with a link 1003 which may be a wired or wireless link.

[0258] Before the PCI is changed, UE 1004 is, for example, in cell 1031 and connected to CU 1002 via DU 1001 using radio link 1021. DU 1001 may control several other cells not shown in the figure. When CU 1002 detects that the PCI of cell 1031 may conflict with other PCIs near cell 1031, CU 1002 may trigger a PCI change procedure, in which a new cell 1032 controlled by DU 1001 is activated, on which UE 1004 may also be connected to CU 1002 via DU 1001 and radio link 1022.

[0259] By CU 1002, for example, by using Fig.11a The described process triggers the activation of the cell 1032. During the activation process, the CU indicates to the DU 1001 the PCI value to be used for the cell 1032.

[0260] Still refer to Figure 8 According to the process described above, once the handover of all UEs such as UE 1004 from cell 1031 to cell 1032 is completed, cell 1032 is deactivated.

[0261] After detecting the completion of the UE handover, the CU 1002 uses Fig.11a The described procedure triggers the deactivation of a cell.

[0262] Fig.10b Another example of a base station or RAN node architecture 1050 is illustrated that enables smooth intra-CU PCI changes or inter-CU PCI changes without service disruption for UEs served by the RAN node.

[0263] Should Fig.10bThe RAN node is shown divided into a CU section (RAN node CU) 1052 and a DU section 1051 connected with a link 1053 which may be a wired or wireless link.

[0264] The DU section 1051 consists of a first logical DU1 (RAN node DU1) 1061 and a second logical DU2 (RAN node DU2) 1062. Both DU1 and DU2 are logical DU entities that share the same hardware for the BAP, RLC and MAC layers. In one embodiment, they share the same physical layer (i.e., the same hardware resources), while in another embodiment, they rely on separate physical layers. In this example, DU1 1061 controls cell 1081 when activated, and DU2 1062 controls cell 1082 when activated. Both DU1 1061 and DU2 1062 can handle several other cells not shown in the figure.

[0265] When both logical DUs are active, only one logical DU is sufficient for operation except at intra-CU PCI change or inter-CU PCI change. For intra-CU PCI change, both logical DUs terminate the F1 interface with the same CU 1052. For inter-CU PCI change, one of the logical DUs terminates the F1 interface with the CU 1052 (which may be referred to as the source CU), while the other logical DU terminates the F1 interface with the target CU shown in the figure.

[0266] Here, inter-CU PCI changes will apply when the source CU and target CU are stationary entities and only the DU entity 1051 is moving (e.g., embedded in a satellite or drone).

[0267] In the case of intra-CU PCI change and before operation, UE 1054 is, for example, in cell 1081 and connected to CU 1052 via DU1 1061 using radio link 1071. DU 1061 may control several other cells not shown in the figure. When CU 1052 detects that the PCI of cell 1081 may conflict with other PCIs near cell 1081, CU 1052 may trigger a PCI change procedure, where logical DU2 1062 is activated together with the new cell 1082, on which UE 1054 may also be connected to CU 1052 via DU2 1062 and radio link 1072.

[0268] By using CU 1052, for example Fig.11a The described process triggers the activation of logical DU2 1062 together with cell 1082. During the activation process, CU 1052 indicates to DU1 1061 the PCI value to be used for cell 1082.

[0269] Once the handover of a UE such as UE 1054 from cell 1081 to cell 1082 is completed, cell 1081 is deactivated.

[0270] After detecting the completion of the UE handover, the CU 1052 uses Fig.11a The described procedure triggers the deactivation of a cell.

[0271] When activating logical DU2 1062, CU 1052 may activate as many cells as the number of cells controlled by logical DU1 1061. All UEs connected through logical DU1 1061 are then handed over via the cells controlled by logical DU2 1062. Once the handover of all UEs is complete, CU 1052 deactivates logical DU1 1061 along with all cells it is controlling.

[0272] After detecting the completion of the UE handover, the CU 1052 may, for example, Fig.11c The described process triggers the deactivation of the logic DU1 1061.

[0273] In the case of inter-CU PCI change and before the operation, UE 1052 is, for example, in cell 1081 and connected to source CU 1052 via logical DU1 1061 using radio link 1071, while logical DU2 1062 is deactivated. During the PCI change process, logical DU2 1062 is activated and connected to the target CU, where UE 1054 can also be connected to the target CU via logical DU2 1062 using cell 1082 and radio link 1072.

[0274] By using the source CU, for example Fig.11a The process described triggers the activation of the logic DU2 1062. During the activation process, the target CU (using Fig.11b The process of ) indicates the PCI value to be used for (one or more than one) cells (such as cell 1082) to be activated with the second logical DU.

[0275] Once the handover of a UE such as UE 1054 from cell 1081 to cell 1082 is completed, cell 1081 is deactivated.

[0276] After detecting the completion of the UE handover, the source CU 1052 uses Fig.11c The described procedure triggers the deactivation of a cell.

[0277] When activating logical DU2 1062, the target CU may activate as many cells as the number of cells controlled by logical DU1 1061. All UEs connected through logical DU1 1061 are then handed over via the cells controlled by logical DU2 1062. Once the handover of all UEs is complete, the source CU 1052 deactivates logical DU1 1061 along with all cells it is controlling.

[0278] After detecting the completion of the UE handover, the source CU 1052 may, for example, Fig.11c The described process triggers the deactivation of the logic DU1 1061 .

[0279] Fig.11a is a flow chart 1100 illustrating an example of a process for performing activation of a logical DU and / or cell(s) according to an embodiment of the present invention. Fig.11a Also used to deactivate (one or more than one) cell.

[0280] The figure shows:

[0281] -It can be a RAN node DU 1101 such as RAN node DU 1001 or 1061 of a gNB-DU, or an IAB node DU such as IAB-DU 711 or 761.

[0282] -It can be a RAN node CU 1102 such as RAN node CU 1002 or 1052 of a gNB-CU, or an IAB donor CU such as IAB donor CU 601 or 602.

[0283] The message CONFIGURATION REQUEST 1103 is sent by the RAN node CU 1102 to the RAN node DU 1101 to request the activation of (one or more) new cells controlled by the RAN node DU 1101, or to request the activation of a second logical DU, or to request the deactivation of (one or more) cells controlled by the RAN node DU 1101.

[0284] The RAN node DU 1101 acknowledges the request by sending a message CONFIGURATION RESPONSE 1104 to the RAN node CU 1102 .

[0285] According to one embodiment of the present invention, Fig.11aThe message 1103 corresponds to the procedure gNB-CU CONFIGURATION UPDATE described in Section 8.2.5 of TS 38.473 V17.0.0, and the message 1104 corresponds to the message gNB-CU CONFIGURATION UPDATE described in Section 9.2.1.10 of TS 38.473 V17.0.0, and the message 1104 corresponds to the message gNB-CU CONFIGURATION UPDATE ACKNOWLEDGE described in Section 9.2.1.11 of TS 38.473 V17.0.0.

[0286] The message GNB-CU CONFIGURATION UPDATE includes an information element (IE) Cells to be Activated List to indicate a list of new cells to be activated with the PCI value(s) to be used. The cell(s) to be activated refer to the cell(s) controlled by the RAN node DU1101 that received the request.

[0287] The message GNB-CU CONFIGURATION UPDATE also includes an information element (IE) Cells to beDeactivated List to indicate a list of (one or more) cells to be deactivated. The (one or more) cells to be deactivated refer to (one or more) cells controlled by the RAN node DU 1101 that received the request.

[0288] According to one embodiment of the present invention, a new IESecond DU Activation (second DU activation) may be added in the message 1103 in the form of a Boolean value to request activation of the second logical DU.

[0289] To complete the setup of a new logical DU, you can use Fig.11b The process described.

[0290] Fig.11b is a flow chart 1110 illustrating an example of a process to set up a logical DU.

[0291] The figure shows:

[0292] -It can be a RAN node DU 1111 such as RAN node DU 1001 or 1061 of a gNB-DU, or an IAB node DU such as IAB-DU 711 or 761.

[0293] -It can be a RAN node CU 1112 such as RAN node CU 1002 or 1052 of a gNB-CU, or an IAB donor CU such as IAB donor CU 601 or 602.

[0294] The message SETUP REQUEST 1113 is sent by the RAN node DU 1101 to the RAN node CU 1102 to request the F1 setup for the logical DU. Fig.11a The activation request is sent afterwards.

[0295] The RAN node CU 1112 replies with a message SETUP RESPONSE 1114 sent to the RAN node DU 1111.

[0296] According to one embodiment of the present invention, Fig.11b Corresponds to the procedure F1 SETUP described in section 8.2.3 of TS 38.473 V17.0.0, and the message 1113 corresponds to the message F1 SETUP REQUEST described in section 9.2.1.4 of TS 38.473 V17.0.0, and the message 1114 corresponds to the message F1 SETUP RESPONSE described in section 9.2.1.5 of TS 38.473 V17.0.0. The message F1 SETUP RESPONSE includes an information element (IE) Cells to be Activated List to indicate a list of (one or more) new cells to be activated with (one or more) PCI values ​​to be used. The (one or more) cells to be activated refer to the (one or more) cells controlled by the RAN node DU 1111 that received the response.

[0297] Fig.11c is a flow chart 1120 illustrating an example of a process to remove a logical DU.

[0298] The figure shows:

[0299] -It can be a RAN node DU 1121 such as RAN node DU 1001 or 1061 of a gNB-DU, or an IAB node DU such as IAB-DU 711 or 761.

[0300] -It can be a RAN node CU 1122 such as RAN node CU 1002 or 1052 of a gNB-CU, or an IAB donor CU such as IAB donor CU 601 or 602.

[0301] A message REMOVAL REQUEST 1123 is sent by the RAN node CU 1122 to the RAN node DU 1121 to request the removal of a logical DU.

[0302] The RAN node DU 1121 replies with a message REMOVAL RESPONSE 1114 sent to the RAN node CU 1122 .

[0303] According to one embodiment of the present invention, Fig.11c corresponds to the procedure F1 REMOVAL described in section 8.2.8 of TS 38.473 V17.0.0, and message 1123 corresponds to the message F1 REMOVALREQUEST described in section 9.2.1.16 of TS 38.473 V17.0.0, and message 1114 corresponds to the message F1 REMOVALRESPONSE described in section 9.2.1.7 of TS 38.473 V17.0.0.

[0304] Fig.12a is a flow chart 1200 illustrating an example of a process used by a RAN node CU to report new usage of (one or more than one) PCI values ​​to another RAN node CU.

[0305] The figure shows two RAN node CUs, RAN node CUa 1201 and RAN node CUb 1202, which may be gNB-CUs (such as RAN node CU 1002 or 1052), or an IAB donor CU such as IAB donor CU 601 or 602.

[0306] The message CONFIGURATION UPDATE 1203 is sent by the RAN node CUa 1201 to the RAN node CUb 1202 to indicate the new PCI(s) usage in the cell(s) managed by the RAN node CUa 1201 .

[0307] According to one embodiment of the present invention, message 1203 corresponds to the message NG-RAN NODE CONFIGURATION UPDATE described in Section 9.1.3.4 of TS 38.423 V17.0.0, which may include a new IE Cells Activated List to indicate a list of (one or more) new cells with (one or more) used PCIs, and may include another new IE Cells Deactivated List to indicate a list of (one or more) removed cells with (one or more) PCIs that are no longer used.

[0308] Figure 12b is a flow chart 1210 illustrating an example of a process used by a RAN node CU to report new usage of (one or more than one) PCI value(s) to the core network.

[0309] The figure shows:

[0310] - a RAN node CU 1211 such as RAN node CU 1002 or 1052, or an IAB donor CU such as IAB donor CU 601 or 602, which may be a gNB-CU,

[0311] -A core network (5GC) 1212 like the core network 110.

[0312] The message CONFIGURATION UPDATE 1213 is sent by the RAN node CU 1211 to the core network 1212 to indicate the use of new PCI(s) in the cell(s) managed by the RAN node CU 1211 .

[0313] According to one embodiment of the present invention, message 1213 corresponds to the message UPLINK RAN CONFIGURATION TRANSFER described in Section 9.2.7.1 of TS 38.413 V17.0.0, which may include a new IE Cells Activated List to indicate a list of (one or more) new cells with (one or more) used PCIs, and include another new IE Cells Deactivated List to indicate a list of (one or more) removed cells with (one or more) PCIs that are no longer used.

[0314] According to another embodiment of the present invention, message 1213 includes a new IE for indicating the location of the cell, for example, using a list of neighbor cells for a dedicated cell. For example, the new IE Neighbor Cells List is used to report a new list of neighbor cells for the cell controlled by the mobile IAB node or the mobile RAN node DU when it has moved.

[0315] Fig.12c is a flow diagram 1220 illustrating an example of a process used by the core network to indicate a list of (one or more than one) PCI values ​​that may be used by a RAN node CU.

[0316] The figure shows:

[0317] - a RAN node CU 1221 such as RAN node CU 1002 or 1052, or an IAB donor CU such as IAB donor CU 601 or 602, which may be a gNB-CU,

[0318] -Core network (5GC) 1222 like core network 110.

[0319] The message CONFIGURATION UPDATE 1213 is sent by the core network 1222 to the RAN node CU 1221 to indicate the new PCI(s) to be used in the cell(s) managed by the RAN node CU 1221 .

[0320] According to one embodiment of the present invention, message 1223 corresponds to the message DOWNLINK RAN CONFIGURATION TRANSFER described in Section 9.2.7.2 of TS 38.413 V17.0.0, which may include a new IE PCIs List to indicate a list of PCIs that can be used.

[0321] According to one embodiment of the present invention, the message 1223 includes a new IE Cells List containing a list of cells, and for each cell, an IE PCIs List indicates a list of PCIs that can be used for the cell.

[0322] Fig.13 Schematic representations showing example communication apparatus (device) or stations according to one or more example embodiments of the present disclosure.

[0323] The communication device 1300 may preferably be a device such as a microcomputer, a workstation or a light portable device. The communication device 1300 includes a communication bus 1113, which is preferably connected to:

[0324] - a central processing unit 1311 denoted as CPU, such as a microprocessor or the like;

[0325] - a memory for storing data and a computer program containing instructions for the operation of the communication device 1300. The computer program may contain many different program elements (modules) or subroutines containing instructions for various operations and for implementing the invention. For example, the program elements include elements for implementing a BAP entity, which is used as described above to route data packets to nodes in the IAB topology; and

[0326] - At least one communication interface 1302 for communicating with other devices or nodes in a wireless communication system (such as a wireless communication system according to Release 16 for 5G NR, etc.). The at least one communication interface 1302 can be connected to a communication network 1303 (such as a radio access network of the system 100, etc.) through which digital data packets or frames or control frames are transmitted. Under the control of a software application running in the CPU 1311, frames are written from a FIFO transmit memory in the RAM 1312 to the communication interface for transmission, or read from the communication interface for reception and written to a FIFO receive memory in the RAM 1312.

[0327] The donor CU, the donor DU, and the IAB node may each include such a communication device 1300 .

[0328] The central processing unit 1311 may be a single processing unit or processor, or may include two or more processing units or processors that perform the processing required for operation of the communication device 1300. The number of processors and the allocation of processing functions to the central processing unit 1311 is a matter of design choice for the skilled person.

[0329] The memory may include:

[0330] - a read-only memory 1307, denoted ROM, for storing a computer program for implementing the invention;

[0331] - A random access memory 1312, represented as a RAM, for storing executable codes of a method according to one or more embodiments of the present invention, and registers adapted to record variables and parameters required to implement a method according to one or more embodiments of the present invention.

[0332] Optionally, the communication device 1300 may further include the following components:

[0333] - data storage means 1304 (such as a hard disk, etc.) for storing a computer program for implementing the method according to one or more embodiments of the invention;

[0334] a disk drive 1305 for a disk 1306, the disk drive being adapted to read data from the disk 1306 or to write data onto said disk;

[0335] - Screen 1309 for displaying the decoded data and / or for use as a graphical interface with the user using a keyboard 1310 or any other pointing means.

[0336] Preferably, the communication bus provides communication and interoperability between the various elements included in or connected to the communication device 1300. The representation of a bus is not limiting, and in particular, the central processing unit is operable to communicate instructions to any element of the communication device 1300, either directly or through other elements of the communication device 1300.

[0337] Disk 1306 can optionally be replaced by any information medium, such as a rewritable or non-rewritable compact disk (CD-ROM), a ZIP disk, a USB key or a memory card, etc., and in general, by an information storage component that can be read by a microcomputer or a microprocessor, is integrated or not integrated into the device, may be removable, and is adapted to store one or more programs (the execution of which enables the method according to an embodiment of the invention to be implemented to be carried out).

[0338] The executable code may optionally be stored in a read-only memory 1307, on a hard disk 1304 or on a removable digital medium (e.g., disk 1306 as previously described, etc.). According to an optional variant, the executable code of the program may be received via the communication network 1303, via the interface 1302, to be stored in one of the storage components of the communication device 1300 (such as the hard disk 1304, etc.) before being executed.

[0339] The central processing unit 1311 is preferably adapted to control and direct the execution of the instructions or software code portions of one or more programs according to the present invention, which are stored in one of the above-mentioned storage components. At power-on, one or more programs stored in a non-volatile memory (e.g., stored in a hard disk 1304 or a read-only memory 1307) are transferred to a random access memory 1312, which then contains the executable code of the one or more programs and registers for storing variables and parameters required to implement the present invention.

[0340] In a preferred embodiment, the device is a programmable device that implements the present invention using software. However, alternatively, the present invention can be implemented in hardware (for example, in the form of an application-specific integrated circuit or ASIC). In an example implementation, a communication device (device) is a programmable device / device that implements the present invention using software. Instructions can be executed by one or more processors (such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuit systems, etc.). Therefore, the term "central processing unit" as used herein may refer to any of the aforementioned structures or any other structure suitable for implementing the technology described herein. However, alternatively, the present invention can be implemented in hardware (for example, in the form of an application-specific integrated circuit or ASIC or other circuit elements).

[0341] Fig.14 An example method according to embodiments and examples of the present invention for managing changes of PCI in one or several cells at a CU of a base station is illustrated using flowchart 1400 .

[0342] At step 1401, the CU determines that the PCI value(s) used by the DU of the remote entity for the cell(s) may conflict / confused with other PCI values ​​near the cell(s), and obtains a new appropriate PCI value(s). For example, the CU may Figure 12b The process described reports the location of the DU and can be used Fig.12c The process receives a PCI value(s) to be used.

[0343] At step 1402, the CU sends a request to a remote entity to activate new cell(s) in the DU using the obtained PCI value(s).

[0344] At step 1403, the CU may receive confirmation for activation from the remote entity. This step is optional.

[0345] At step 1404, the CU triggers intra-DU handover for UEs served in the cell(s) having PCI conflict / confusion.

[0346] At step 1405, when the CU detects that the UE handover is complete, the CU sends a request to the remote entity to deactivate the cell(s) having the PCI conflict / confusion.

[0347] At step 1406, the CU may receive confirmation of deactivation of the cell(s) from the remote entity. This step is optional.

[0348] As an alternative, the remote entity is the DU itself.

[0349] Fig.15 Another example method according to embodiments and examples of the present invention for managing changes of PCI in one or several cells at a CU of a base station is illustrated using flowchart 1500 .

[0350] At step 1501, the CU determines that the (one or more) PCI value used by the first DU of the remote entity for the (one or more) cell may conflict / be confused with other PCI values ​​near the (one or more) cell, and obtains a new suitable (one or more) PCI value.

[0351] At step 1502, the CU sends a request to a remote entity to activate new cell(s) in the second DU using the obtained PCI value(s). This step may include activating the second DU if it is not already activated.

[0352] At step 1503, the CU may receive confirmation for activation from the remote entity. This step is optional.

[0353] At step 1504, the CU triggers a handover from the first DU to the second DU for UEs served in the cell(s) with PCI conflict / confusion. As an alternative step, the CU triggers a handover for all UEs served by the first DU.

[0354] At step 1505, when the CU detects that the UE handover is complete, the CU sends a request to the remote entity to deactivate the cell(s) of the first DU having the PCI conflict / confusion.

[0355] At step 1506, the CU sends a request to the remote entity to remove the first DU. This step is optional. As an alternative, step 1505 is skipped and step 1506 involves automatic deactivation of the cell(s) controlled by the first DU.

[0356] At step 1507, the CU may receive confirmation from the remote entity for the deactivation of the cell(s) and / or for the removal of the first DU. This step is optional.

[0357] Fig.16 An example method according to embodiments and examples of the present invention for managing migration of an IAB node including a change of PCI in one or several cells at a target donor CU is illustrated using flow chart 1600 .

[0358] At step 1601 , a target donor CU receives a node migration request for an IAB node including a first DU from a source donor CU.

[0359] At step 1602, the target donor CU obtains PCI value(s) to be used for cell(s) by the second DU of the migration node, which PCI value(s) may not conflict / confused with other nearby PCI values.

[0360] At step 1603, the target donor CU sends a request to the migration node to activate the new cell(s) in the second DU using the obtained PCI value(s).

[0361] Then, you can apply Fig.15 Steps 1504 to 1507.

[0362] Regarding PCI partition restrictions, it is acknowledged that PCI conflict avoidance through OAM and PCI partitioning is not enough for some mobile IAB scenarios. First, the trajectory of a mobile IAB node may not always be predictable because it depends on the type of vehicle (e.g., taxi) or scenario (e.g., temporary deployment). Thus, dedicating some specific PCI values ​​to mobile IAB nodes will involve preventing these PCI values ​​from being used for any other RAN cell. Due to the reduction in available PCI space, this will impose a high degree of constraint on stationary RAN cells. Therefore, the deployment of mobile IAB nodes may be restricted. In order to avoid adding such excessive constraints, the number of PCI values ​​dedicated to mobile IAB nodes can be limited to a few values. Unless the number of mobile IAB nodes in the same geographic area is limited to this number of dedicated PCI values, PCI conflicts or confusion situations where two mobile IAB nodes are close to each other and use the same PCI value cannot be avoided.

[0363] Furthermore, PCI planning should not only avoid PCI conflicts or confusion with the same PCI value for two neighboring cells (directly adjacent to a common cell or adjacent to a common cell), but PCI planning can also minimize situations of signal interference that affect network performance (e.g., situations with the same PCI mode 3 result (same PSS detected), situations with the same PCI mode 4 result (DMRS interference)). Even in the case of PCI partitions with dedicated values, such PCI planning optimization will not be feasible in the case of mobile cells.

[0364] The result is a need to be able to change the PCI value of one or several cells of a mobile IAB node. This does not exclude PCI partitioning with dedicated PCI values ​​for mobile IAB nodes. The advantage of PCI partitioning would be to reduce the number of cases where a PCI change is required when a mobile IAB node is moving.

[0365] Therefore, regardless of whether PCI partitioning is applied, PCI conflict avoidance via dynamic PCI changes should be considered.

[0366] Additionally, it would be beneficial to avoid service interruption for UEs served by a mobile IAB node when the PCI value of the serving cell is dynamically changed.

[0367] Thus, dynamic PCI changes without service interruption for served UEs should be considered and may be referred to as smooth PCI changes.

[0368] For smoothing PCI changes, two processes can be considered:

[0369] 1) Inter-Donor CU PCI Change procedure, where the PCI value is modified at the mobile IAB-DU, and this procedure is applied when the mobile IAB node is during a full migration towards a new IAB donor CU.

[0370] 2) Intra-Donor CU PCI Change procedure, where the PCI value is modified at the mobile IAB-DU, and this procedure is applied when the mobile IAB node is not fully migrating towards a new IAB donor CU.

[0371] Considering the first process (PCI change between donor CUs), the full migration of the mobile IAB node is indeed an opportunity to change the (one or more) PCI value used by the mobile IAB node in the event of a potential conflict. Smooth PCI changes can be achieved by relying on an architecture that enables two logical DUs at the mobile IAB node. Then, when the second logical DU (under the target donor CU) is activated in the mobile IAB node, the activated (one or more) cells can use (one or more) new PCI values ​​that are different from the (one or more) PCI values ​​used for the (one or more) cells controlled by the first logical DU (under the source donor CU). At the time of the full migration of the mobile IAB node, the served UE also migrates from the source donor CU to the target donor CU. The UE served by the first logical DU will be handed over from the cell controlled by the first logical DU to the cell controlled by the second logical DU through the legacy handover process (described in Section 9.2.3.2 of TS 38.300V17.0.0). Once handover is completed for all UEs served by the first logical DU, the first logical DU may be deactivated.

[0372] Considering the second process (PCI change within the donor CU), a smooth PCI change can be achieved by activating a new cell with a new PCI value in the mobile IAB-DU. The UE served by the cell with potential PCI conflict will be handed over to the new cell with the new PCI value through the legacy handover process (described in Section 9.2.3.2 of TS38.300 V17.0.0). Once the handover is completed for all UEs served in the cell with potential PCI conflict, the cell can be deactivated.

[0373] Thus, in one aspect of the present invention, two processes may be considered for smoothing PCI changes:

[0374] 1) Inter-donor CU PCI change process when the mobile IAB node is fully migrating towards a new IAB donor CU, and

[0375] 2) PCI changes within the donor CU when the mobile IAB node is not fully migrating towards a new IAB donor CU.

[0376] Although the present invention has been described with reference to the embodiments, it should be understood that the present invention is not limited to the disclosed embodiments. It will be appreciated by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention as defined in the appended claims. All features disclosed in this specification (including any appended claims, abstracts and drawings) and / or all steps of any method or process so disclosed may be combined in any combination other than at least some mutually exclusive combinations of such features and / or steps. Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims, abstracts and drawings) may be replaced by an alternative feature serving the same, equivalent or similar purpose. Thus, unless otherwise expressly stated, each feature disclosed is only an example of an equivalent or similar feature of a general series.

[0377] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

[0378] In the foregoing embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on or transmitted through a computer-readable medium and executed by a hardware-based processing unit.

[0379] Computer-readable media may include computer-readable storage media corresponding to tangible media such as data storage media, or communication media, including any media that facilitates the transfer of a computer program from one location to another, for example, according to a communication protocol. In this manner, computer-readable media may generally correspond to (1) non-transitory tangible computer-readable storage media or (2) communication media such as signals or carrier waves. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures to implement the techniques described in the present disclosure. A computer program product may include computer-readable media.

[0380] As an example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store the desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition, any connection is appropriately referred to as a computer-readable medium. For example, if a coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave are used to transmit instructions from a website, server or other remote source, then the coaxial cable, optical fiber cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of the medium. However, it should be understood that computer-readable storage media and data storage media do not include connection, carrier wave, signal or other transient media, but point to non-transient tangible storage media. As used herein, disk (disk and disc) includes compact disk (CD), laser disk, optical disk, digital versatile disk (DVD), floppy disk and blue disc, wherein disk (disk) usually reproduces data magnetically, and disk (disc) reproduces data optically with laser. Combinations of the above should also be included within the scope of computer-readable media.

Claims

1. A method for avoiding physical cell identity conflicts in a wireless network, namely, a PCI conflict avoidance method, wherein the wireless network includes a first base station controlling a first cell, the first cell having a first PCI, the method comprising: Determine a conflict between the first PCI and a PCI of another cell near the first cell; as well as A second cell having a second PCI is activated, wherein the second PCI is different from the first PCI.

2. The method according to claim 1, wherein: The step of determining a conflict between the first PCI and a PCI of another cell near the first cell is performed by the first base station.

3. The method according to claim 1, wherein: The step of determining a conflict between the first PCI and a PCI of another cell near the first cell is performed by a second base station of the wireless network.

4. The method according to claim 1, wherein: The step of determining a conflict between the first PCI and a PCI of another cell near the first cell is performed by a core network controlling the wireless network.

5. The method according to any one of the preceding claims, further comprising the steps of: A value of the second PCI is determined.

6. The method according to claim 5, wherein: The step of determining a value of the second PCI is performed by the first base station.

7. The method according to claim 5, wherein: The step of determining a value of the second PCI is performed by a second base station of the wireless network.

8. The method according to claim 6 or 7, wherein: The step of determining the value of the second PCI is performed by a central unit, CU, of the base station.

9. The method according to claim 5, wherein: The step of determining the value of the second PCI is performed by a core network controlling the wireless network.

10. A method according to any one of the preceding claims, wherein: The step for activating the second cell is performed by a distributed unit, DU, of the first base station controlling the first cell.

11. The method according to claim 10, wherein: The step for activating the second cell is performed in response to a request of a central unit, CU, of the first base station.

12. The method according to any one of claims 1 to 9, wherein: The first cell is controlled by a first distributed unit, ie, a first DU, of the first base station, and the step for activating the second cell is performed by a second distributed unit, ie, a second DU, of the first base station.

13. The method according to claim 12, wherein: The step of activating the second cell is performed in response to a request of the CU of the first base station.

14. The method according to any one of claims 10 to 13, wherein: The wireless network serves a user equipment, the user equipment initially connected to the first base station via a radio link in the first cell, the method further comprising the steps of: Following activation of the second cell, the user equipment is connected to the first base station via a radio link in the second cell.

15. The method according to any one of claims 1 to 9, wherein: The first cell is controlled by a distributed unit, DU, of the first base station, and the step for activating the second cell is performed by the DU of the second base station.

16. The method according to claim 15, wherein: The step of activating the second cell is performed in response to a request of the CU of the second base station.

17. The method according to claim 15 or 16, wherein: The wireless network serves a user equipment, the user equipment initially connected to the first base station via a radio link in the first cell, the method further comprising the steps of: Following activation of the second cell, the user equipment is connected to a second base station via a radio link in the second cell.

18. The method according to any one of claims 12 to 17, wherein: The first distributed unit or the second distributed unit is a logical distributed unit entity.

19. The method according to any one of claims 12 to 17, wherein: Both the first distributed unit and the second distributed unit are logical distributed unit entities sharing the same physical layer.

20. The method according to any one of claims 12 to 17, wherein: Both the first distributed unit and the second distributed unit are logical distributed unit entities having separate physical layers.

21. A method according to any one of the preceding claims, wherein: The first base station is a next generation radio access network node.

22. The method according to any one of claims 1 to 20, wherein: The first base station is a CU of an integrated access and backhaul donor node, ie, an IAB donor node.

23. The method according to any one of claims 10 to 20, wherein: The first base station is a CU of an integrated access and backhaul donor node, ie, an IAB donor node, and the DU or DUs are DUs of an IAB node of an IAB topology controlled by the donor CU.

24. The method according to claim 23, wherein: The IAB node is a mobile IAB node.

25. The method according to any one of the preceding claims, further comprising the steps of: Deactivate the first cell.

26. The method according to any one of claims 10 to 25, further comprising the steps of: Deactivate the first DU.

27. A base station configured to perform a method according to any preceding claim.

28. A method for a central unit (CU) of an integrated access and backhaul donor node (IAB donor node), the CU of the IAB donor node controlling an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (DU) of the IAB node of the IAB topology, the method comprising: Determine a conflict between a physical cell identifier (PCI) of the first cell and a PCI of another cell near the first cell; Obtaining a new PCI that does not cause a conflict with a PCI of another cell near the first cell; as well as The IAB node is instructed to activate a second cell having the new PCI by using the first DU of the IAB node.

29. The method according to claim 28, wherein: The user equipment is initially connected to the CU of the IAB donor node via a radio link in the first cell, the method further comprising the steps of: and triggering an intra-DU handover of the user equipment from the first cell to the second cell.

30. The method according to claim 28 or 29, further comprising the steps of: Instruct the IAB node to deactivate the first cell using the first DU of the IAB node.

31. A method for a central unit (CU) of an integrated access and backhaul donor node (IAB donor node), the CU of the IAB donor node controlling an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (first DU) of the IAB node of the IAB topology, the method comprising: Determine a conflict between a physical cell identifier (PCI) of the first cell and a PCI of another cell near the first cell; Obtaining a new PCI that does not cause a conflict with a PCI of another cell near the first cell; as well as The IAB node is instructed to activate a second cell having the new PCI by using a second DU of the IAB node.

32. The method according to claim 31, wherein: The user equipment is initially connected to the CU of the IAB donor node via a radio link in the first cell, the method further comprising the steps of: and triggering an inter-DU handover of the user equipment from the first cell to the second cell.

33. The method according to claim 31 or 32, further comprising the steps of: Instruct the IAB node to deactivate the first cell using the first DU of the IAB node.

34. The method according to any one of claims 31 to 33, further comprising the steps of: Instruct the IAB node to deactivate the first DU.

35. A method for a central unit (CU) of a target integrated access and backhaul donor node (target IAB donor node), wherein the CU of the target IAB donor node controls a target IAB topology, the method comprising: receiving, from a CU of a source IAB donor node for controlling a source IAB topology, a node migration request for migrating an IAB node of the source IAB topology, the IAB node comprising a first distributed unit (i.e., a first DU) having established a first cell having a first physical cell identifier (i.e., a first PCI); Using the CU of the target IAB donor node, obtaining a new PCI that does not cause a conflict with a PCI of another cell near the first cell; as well as The second DU of the IAB node indicating the migration of the source IAB topology establishes a second cell with the new PCI by using the CU of the target IAB donor node.

36. The method according to claim 35, further comprising the steps of: Instruct the IAB node to deactivate the first cell using the first DU of the IAB node.

37. The method according to claim 35 or 36, further comprising the steps of: Instruct the IAB node to deactivate the first DU.

38. A base station, configured to perform a physical cell identity conflict avoidance method, i.e., a PCI conflict avoidance method, in a wireless network, the wireless network comprising the base station, the base station controlling a first cell having a first PCI, the base station comprising: means for determining a conflict between the first PCI and a PCI of another cell near the first cell; as well as Means for activating a second cell having a second PCI, wherein the second PCI is different from the first PCI.

39. An integrated access and backhaul donor node (IAB donor node), comprising a central unit (CU), the CU being configured to control an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (first DU) of the IAB node of the IAB topology, the IAB donor node comprising: A component for determining a conflict between a physical cell identity (PCI) of the first cell and a PCI of another cell near the first cell; means for obtaining a new PCI that does not cause a conflict with a PCI of another cell in the vicinity of the first cell; as well as means for instructing the IAB node to activate a second cell having the new PCI using the first DU of the IAB node.

40. The IAB donor node of claim 39, wherein: A user equipment is initially connected to the CU of the IAB donor node via a radio link in the first cell, the IAB donor node further comprising: means for triggering an intra-DU handover of the user equipment from the first cell to the second cell.

41. The IAB donor node of claim 40, further comprising: A component for instructing the IAB node to deactivate the first cell using the first DU of the IAB node.

42. An integrated access and backhaul donor node (IAB donor node), comprising a central unit (CU), the CU being configured to control an IAB topology, the IAB topology comprising a first cell established by a first distributed unit (first DU) of the IAB node of the IAB topology, the IAB donor node comprising: A component for determining a conflict between a physical cell identity (PCI) of the first cell and a PCI of another cell near the first cell; means for obtaining a new PCI that does not cause a conflict with a PCI of another cell in the vicinity of the first cell; as well as means for instructing the IAB node to activate a second cell having the new PCI using a second DU of the IAB node.

43. The IAB donor node of claim 42, wherein: A user equipment is initially connected to the CU of the IAB donor node via a radio link in the first cell, the IAB donor node further comprising: A means for triggering an inter-DU handover of the user equipment from the first cell to the second cell.

44. The IAB donor node of claim 43, further comprising: A component for instructing the IAB node to deactivate the first cell using the first DU of the IAB node.

45. The IAB donor node according to any one of claims 42 to 44, further comprising: A component for instructing the IAB node to deactivate the first DU.

46. ​​An integrated access and backhaul donor node, or IAB donor node, comprising a central unit, or CU, the CU controlling a target IAB topology, the IAB donor node comprising: means for receiving, from a CU of a source IAB donor node for controlling a source IAB topology, a node migration request for migrating an IAB node of the source IAB topology, the IAB node comprising a first distributed unit (i.e., a first DU) having established a first cell having a first physical cell identifier (i.e., a first PCI); means for obtaining a new PCI that does not cause a conflict with a PCI of another cell in the vicinity of the first cell; as well as The second DU of the IAB node for instructing migration of the source IAB topology establishes means for a second cell having the new PCI.

47. A computer program comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 37.

48. A computer readable medium carrying a computer program according to claim 47.

Images