A conditional procedure for adding and modifying secondary nodes (SNs) initiated by the SN

Abstract

Aspects of the present disclosure relate to wireless communications, and more particularly, to a procedure for supporting conditional new radio (NR) secondary node (SN) addition and change by using a conditional handover (CHO) procedure. A method that may be implemented by a user equipment (UE) includes receiving, from a master node (MN), configuration information identifying a set of candidate cells for a conditional addition or change of SN for the UE based on an execution criterion, detecting that the execution criterion is met for one of the candidate cells, and taking action to add or change the candidate cell as an SN based on the detection.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 17 / 089,565, filed November 4, 2020, which claims the benefit of and priority to U.S. Provisional Application No. 62 / 931,651, filed November 6, 2019, which is assigned to the assignee of this application and is expressly incorporated by reference in its entirety for all applicable purposes as if fully set forth below.

[0002] Aspects of the present disclosure relate to wireless communication, and more particularly, to a procedure for supporting conditional new radio (NR) secondary node (SN) addition and change by reusing a conditional handover (CHO) procedure. [Background technology]

[0003]

[0003] Wireless communication systems have been widely deployed to provide various telecommunication services, such as telephone, video, data, messaging, and broadcast. A typical wireless communication system may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple access technologies include Long Term Evolution (LTE) systems, Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems.

[0004]

[0004] In some examples, a wireless multiple-access communication system may include several base stations (BSs), each simultaneously supporting communication for several communication devices, sometimes known as user equipment (UE). In an LTE or LTE-A network, a set of one or more BSs may define an eNodeB (eNB). In other examples (e.g., in a next-generation or 5G network), a wireless multiple-access communication system may include several distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmit reception points (TRPs), etc.) in communication with several central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units in communication with the central units may define an access node (e.g., new radio base station (NR BS), new radio node B (NR NB), network node, 5G NB, gNode B (gNB), etc.). A BS or DU may communicate with a set of UEs on a downlink channel (e.g., for transmissions from the BS or to the UEs) and on an uplink channel (e.g., for transmissions from the UEs to the BS or DU).

[0005]

[0005] These multiple access technologies are being adopted in various telecommunication standards to provide a common protocol that allows different wireless devices to communicate on a city, national, regional, or even global scale. One example of an emerging telecommunication standard is called New Radio (NR), e.g., 5G radio access. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, lowering costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefix (CP) on the downlink (DL) and on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation (CA).

[0006]

[0006] However, as the demand for mobile broadband access continues to increase, further improvements in NR technology are needed. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunications standards that employ these technologies. Summary of the Invention

[0007]

[0007] The systems, methods, and devices of the present disclosure each have several aspects, and no single aspect of the aspects is solely responsible for the desirable attributes of the present disclosure. Next, some features will be briefly described without limiting the scope of the present disclosure as expressed by the following claims. After considering this description, and especially after reading the section entitled "Description of the Preferred Embodiments," it will be understood how the features of the present disclosure provide advantages including improved communication between access points and stations in a wireless network.

[0008] Certain aspects relate to a method for wireless communication by a secondary node (SN). The method generally includes identifying a set of one or more candidate cells for conditional addition or change as a SN for a user equipment (UE) based on execution criteria, and signaling information regarding the set of candidate cells to a master node (MN).

[0009]

[0009] Certain aspects relate to a method for wireless communication by a MN. The method generally includes receiving signaling from a SN that identifies a set of candidate cells for conditional addition or change as a SN for the UE based on an execution criterion, and signaling configuration information regarding the set of candidate cells to the UE.

[0010]

[0010] Certain aspects relate to a method for wireless communication by a UE. The method generally includes receiving, from a MN, configuration information identifying a set of candidate cells and performance criteria for conditional addition or change as a SN for the UE, where the performance criteria is obtained from the MN in a transparent container, detecting that the performance criteria is met for one of the candidate cells, and taking action to add or change as a SN for the candidate cell based on the detection.

[0011]

[0011] Some aspects relate to an apparatus for wireless communication by a SN, comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to identify a set of one or more candidate cells for conditional addition or modification of the SN for a UE based on an execution criterion; and signal information regarding the set of candidate cells to the MN.

[0012]

[0012] Some aspects relate to an apparatus for wireless communication by a MN, comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to receive signaling from an SN identifying a set of candidate cells for conditional addition or modification of the SN for the UE based on an execution criterion; and signaling configuration information regarding the set of candidate cells to the UE.

[0013]

[0013] Some aspects relate to an apparatus for wireless communication by a UE, comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to receive, from an MN, configuration information identifying a set of candidate cells and execution criteria for conditional addition or change of a SN for the UE, detect that the execution criteria is met for one of the candidate cells, and take action to add or change the candidate cell as an SN based on the detection.

[0014]

[0014] Aspects generally include methods, apparatus, systems, computer readable media, and processing systems substantially as described herein with reference to and as illustrated by the accompanying drawings.

[0015]

[0015] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of the various aspects may be employed, and the description is intended to include all such aspects and their equivalents.

[0016]

[0016] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description briefly summarized above may be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only some typical embodiments of the present disclosure, and therefore should not be considered as limiting the scope of the present disclosure, since the description may lead to other equally effective embodiments. [Brief description of the drawings]

[0017] [Figure 1]

[0017] A block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure. [Diagram 2]

[0018] FIG. 1 is a block diagram illustrating an example architecture of a distributed radio access network (RAN) in accordance with certain aspects of the present disclosure. [Diagram 3]

[0019] FIG. 1 is a block diagram conceptually illustrating an example base station (BS) and user equipment (UE) design in accordance with certain aspects of the present disclosure. [Figure 4]

[0020] 1 illustrates an example call flow diagram for determining a handover (HO) configuration for a RAN handover procedure, in accordance with certain aspects of the present disclosure. [Diagram 5] 1 illustrates an example call flow diagram for determining a handover (HO) configuration for a RAN in accordance with certain aspects of the present disclosure. [Figure 6]

[0021] FIG. 1 illustrates example operations for wireless communication by a master node (MN) in accordance with certain aspects of the present disclosure. [Figure 7]

[0022] 4 illustrates example operations for wireless communication by a UE, in accordance with certain aspects of the present disclosure. [Figure 8]

[0023] FIG. 1 illustrates example operations for wireless communication by a secondary node (SN) in accordance with certain aspects of the present disclosure. [Figure 9]

[0024] 1 is a first call flow diagram illustrating example communications between a UE, a MN, and a SN, in accordance with various aspects of the present disclosure. [Figure 10]

[0025] 4 is a second call flow diagram illustrating example communications between a UE, a MN, and a SN, in accordance with various aspects of the present disclosure. [Figure 11]

[0026] FIG. 1 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein, in accordance with aspects of the present disclosure. [Figure 12]

[0027] FIG. 1 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein, in accordance with aspects of the present disclosure. [Figure 13]

[0028] FIG. 1 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein, in accordance with aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018]

[0029] For ease of understanding, wherever possible, the same reference numbers have been used to designate like elements that are common to each of the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

[0019]

[0030] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for supporting conditional (e.g., New Radio (NR)) secondary node (SN) additions and changes by reusing conditional handover (CHO) procedures.

[0020]

[0031] Some aspects of the present disclosure may be applied to New Radio (NR) (New Radio Access Technology or 5G Technology). NR supports various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., above 80 MHz), millimeter wave (mmW) targeting high carrier frequency (e.g., 60 GHz), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and / or mission critical targeting ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet their respective quality of service (QoS) requirements. Furthermore, these services may coexist in the same subframe.

[0021]

[0032] The following description provides examples and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and configuration of the elements described without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of aspects described herein. Furthermore, the scope of the disclosure is intended to cover such apparatus or methods implemented using other structures, functions, or structures and functions in addition to or other than the various aspects of the disclosure described herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0022]

[0033] The techniques described herein may be used for various wireless communication networks, such as Long Term Evolution (LTE), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). NR is an emerging wireless communications technology under development with the 5G Technology Forum (5GTF). 3GPP® LTE and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies.For clarity, aspects may be described herein using terminology commonly associated with 3G and / or 4G wireless technology, although aspects of the disclosure may be applied in other generation-based communication systems, such as 5G and beyond, including NR technology.

[0023] EXAMPLE WIRELESS COMMUNICATIONS SYSTEM

[0034] FIG. 1 illustrates an example wireless network 100 in which aspects of the present disclosure may be implemented. For example, the wireless communication network 100 may be a new radio (NR) system (e.g., a 5G NR network). For example, as shown in FIG. 1, a user equipment (UE) 120a may include a handover manager 142, which may be configured to receive configuration information identifying a set of candidate cells for a conditional addition or change of a secondary node (SN) for the UE based on an execution criterion. The handover manager 142 may also be configured to detect whether the execution criterion is met for one of the candidate cells. If the execution criterion is met for one of the candidate cells, the handover manager 142 may also be configured to perform a conditional addition or change to the candidate cell as a SN based on the detection.

[0024]

[0035] Similarly, the base station (BS) 110a has a handover manager 144 that may be configured for handover operations. For example, when the BS 110a acts as an SN, the handover manager 144 may be configured to identify a set of candidate cells for conditional addition or change of SN for the UE based on performance criteria. The handover manager 144 may also be configured to signal configuration information regarding the set of candidate cells to a master node (MN). In another example, when the BS 110a acts as an MN, the handover manager 144 may be configured to receive signaling from an SN that identifies a set of candidate cells for conditional addition or change of SN for the UE based on performance criteria. The handover manager 144 may also be configured to signal configuration information regarding the set of candidate cells to the UE.

[0025]

[0036] As shown in FIG. 1, the wireless network 100 may include several BSs 110 and other network entities. A BS may be a station that communicates with UEs. Each BS 110 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to a coverage area of ​​a Node B and / or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In an NR system, the terms "cell" and eNB, Node B, 5G NB, AP, NR BS, NR BS, or TRP may be interchangeable. In some examples, a cell may not necessarily be fixed, and the geographic area of ​​a cell may move according to the location of a mobile base station. In some examples, the base stations may be interconnected to each other and / or to one or more other base stations or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces, such as direct physical connections, virtual networks, etc., using any suitable transport network.

[0026]

[0037] Generally, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. The RAT may also be referred to as a radio technology, an air interface, etc. The frequencies may also be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

[0027]

[0038] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a few kilometers in radius) and may allow unrestricted access by UEs with a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for a pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or multiple (e.g., three) cells.

[0028]

[0039] Wireless network 100 may also include relay stations. A relay station is a station that receives a transmission of data and / or other information from an upstream station (e.g., a BS or UE) and sends a transmission of the data and / or other information to a downstream station (e.g., a UE or BS). A relay station may also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, relay station 110r may communicate with BS 110a and UE 120r to facilitate communication between BS 110a and UE 120r. A relay station may also be referred to as a relay BS, a relay, etc.

[0029]

[0040] Wireless network 100 may be a heterogeneous network including different types of BSs, e.g., macro BSs, pico BSs, femto BSs, relays, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 20 watts), while a pico BS, femto BS, and relays may have a lower transmit power level (e.g., 1 watt).

[0030]

[0041] The wireless network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

[0031]

[0042] A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with each other, directly or indirectly, e.g., via a wireless or wireline backhaul.

[0032]

[0043] The UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless network 100, and each UE may be fixed or mobile. A UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smartphone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet, camera, gaming device, netbook, smartbook, ultrabook, medical device or equipment, biometric sensor / device, wearable device such as smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate over a wireless or wired medium. Some UEs may be considered evolved or machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC UEs and eMTC UEs include, for example, a robot, a drone, a remote device, a sensor, a meter, a monitor, a location tag, etc. that may communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices.

[0033]

[0044] In Figure 1, a solid line with double arrows indicates a desired transmission on the downlink and / or uplink between a UE and a serving BS, which is a BS designated to serve that UE, and a dashed line with double arrows indicates an interfering transmission between the UE and a BS.

[0034]

[0045] Some wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz, and the minimum resource allocation (called a "resource block") may be 12 subcarriers (or 180 kHz). Thus, the nominal fast Fourier transform (FFT) size may be equal to 128, 256, 512, 1024, or 2048 for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.8 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for 1.25, 2.5, 5, 10, or 20 MHz system bandwidths, respectively.

[0035]

[0046] Although example aspects described herein may relate to LTE technology, aspects of the present disclosure may be applicable in conjunction with other wireless communication systems, such as NR.

[0036]

[0047] NR utilizes OFDM with CP on the uplink (UL) and downlink (DL) and may include support for half-duplex operation using time division duplexing (TDD). A single component carrier bandwidth of 100 MHz may be supported. An NR resource block may span 12 subcarriers with a subcarrier bandwidth of 75 kHz over a 0.1 ms duration. Each radio frame may consist of 50 subframes with a length of 10 ms. Thus, each subframe may have a length of 0.2 ms. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission, and the link direction for each subframe may be dynamically switched. Each subframe may include DL / UL data as well as DL / UL control data.

[0037]

[0048] Beamforming may be supported and beam directions may be dynamically configured. Multiple-input multiple-output (MIMO) transmission with precoding may also be supported. MIMO configuration in DL may support up to eight transmit antennas with multi-layer DL transmission of up to eight streams and up to two streams per UE. Multi-layer transmission with up to two streams per UE may be supported. Aggregation of multiple cells may be supported with up to eight serving cells. Alternatively, NR may support different air interfaces other than OFDM-based. An NR network may include entities such as a CU and / or a DU.

[0038]

[0049] In some examples, access to the air interface may be scheduled, where a scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. Within this disclosure, as described further below, the scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, the subordinate entities utilize resources allocated by the scheduling entity. The BS is not the only entity that may function as a scheduling entity. That is, in some examples, a UE may function as a scheduling entity that schedules resources for one or more subordinate entities (e.g., one or more other UEs). In this example, the UE is functioning as the scheduling entity, and the other UEs utilize the resources scheduled by the UE for wireless communication. The UE may function as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In a mesh network example, the UEs may optionally communicate directly with each other in addition to communicating with the scheduling entity.

[0039]

[0050] Thus, in wireless communication networks having cellular, P2P and mesh configurations with scheduled access to time-frequency resources, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.

[0040]

[0051] As mentioned above, a radio access network (RAN) may include a central unit (CU) and a distributed unit (DU). An NR BS (e.g., gNB, 5G Node B, Node B, Transmit Reception Point (TRP), Access Point (AP)) may correspond to one or more BSs. An NR cell may be configured as an access cell (ACell) or a data-only cell (DCell). For example, a RAN (e.g., a central unit or a distributed unit) may configure a cell. A DCell may be a cell used for carrier aggregation (CA) or dual connectivity but not used for initial access, cell selection / reselection, or handover. In some cases, a DCell may not transmit a synchronization signal, and in some cases, a DCell may transmit synchronization signaling (SS). An NR BS may transmit a DL signal indicating a cell type to a UE. Based on the cell type indication, the UE may communicate with an NR BS. For example, a UE may determine an NR BS to consider for cell selection, access, handover, and / or measurement based on the indicated cell type.

[0041]

[0052] Figure 2 shows an example architecture of a distributed RAN 200 that may be implemented in the wireless communications network 100 shown in Figure 1. As shown in Figure 2, the distributed RAN includes a core network (CN) 202 and an access node 208 (e.g., BS 110a in Figure 1).

[0042]

[0053] The CN 202 may host core network functions. The CN 202 may be deployed centrally. The CN 202 functions may be offloaded (e.g., to Advanced Wireless Services (AWS)) in an attempt to handle peak capacity. The CN 202 may include an Access and Mobility Management Function (AMF) 204 and a User Plane Function (UPF) 206. The AMF 204 and the UPF 206 may implement one or more of the core network functions.

[0043]

[0054] The AN 208 may communicate with the CN 202 (e.g., via a backhaul interface). The AN 208 may communicate with the AMF 204 via an N2 (e.g., NG-C) interface. The AN 208 may communicate with the UPF 206 via an N3 (e.g., NG-U) interface. The AN 208 may include a central unit control plane (CU-CP) 210, one or more central unit user planes (CU-UP) 212, one or more DUs 214-218, and one or more antenna / remote radio units (AU / RRUs) 220-224. The CU and DU may also be referred to as gNB-CU and gNB-DU, respectively. One or more components of the AN 208 may be implemented in the gNB 226. The AN 208 may communicate with one or more neighboring gNBs / BSs.

[0044]

[0055] The CU-CP 210 may be connected to one or more of the DUs 214-218. The CU-CP 210 and the DUs 214-218 may be connected via an F1-C interface. As shown in FIG. 2, the CU-CP 210 may be connected to multiple DUs, but a DU may be connected to only one CU-CP. Although FIG. 2 shows only one CU-UP 212, the AN 208 may include multiple CU-UPs. The CU-CP 210 selects an appropriate CU-UP(s) for the requested service (e.g., for the UE 120a). The CU-UP(s) 212 may be connected to the CU-CP 210. For example, the DU-UP(s) 212 and the CU-CP 210 may be connected via an E1 interface. The CU-CP(s) 212 may be connected to one or more of the DUs 214-218. The CU-UP(s) 212 and the DUs 214-218 may be connected via an F1-U interface. As shown in Figure 2, the CU-CP 210 may be connected to multiple CU-UPs, but a CU-UP may be connected to only one CU-CP.

[0045]

[0056] A DU, such as DU 214, 216, and / or 218, may host one or more TRPs (transmission / reception points, which may include edge nodes (ENs), edge units (EUs), radio heads (RHs), smart radio heads (SRHs), etc.). A DU may be located at the edge of a network with radio frequency (RF) capabilities. A DU may be connected to multiple CU-UPs (e.g., under the control of the same CU-CP) that are connected to the same CU-CP (e.g., for RAN sharing, radio as a service (RaaS), and service-specific deployments). The DUs may be configured to serve traffic to a UE individually (e.g., dynamic selection) or together (e.g., joint transmission). Each DU 214-216 may be connected to one of the AU / RRUs 220-224.

[0046]

[0057] The CU-CP 210 may be connected to multiple DUs connected to the same CU-UP 212 (e.g., under the control of the same CU-UP 212). Connectivity between the CU-UP 212 and the DU may be established by the CU-CP 210. For example, connectivity between the CU-UP 212 and the DU may be established using a bearer context management function. Data forwarding between the CU-UP 212(s) may be via an Xn-U interface.

[0047]

[0058] The distributed RAN 200 may support fronthauling solutions across different deployment types. For example, the RAN 200 architecture may be based on transmission network capabilities (e.g., bandwidth, latency, and / or jitter). The distributed RAN 200 may share features and / or components with LTE. For example, the AN 208 may support dual connectivity with NR and share a common fronthaul for LTE and NR. The distributed RAN 200 may enable cooperation between the DUs 214-218, for example, via the CU-CP 212. The inter-DU interface may not be used.

[0048]

[0059] FIG. 3 shows a block diagram of a design of BS 110, which may be one of the BSs in FIG. 1, and UE 120, which may be one of the UEs in FIG. 1. In the case of a restricted association scenario, BS 110 may be macro BS 110c in FIG. 1, and UE 120 may be UE 120y. BS 110 may also be any other type of BS shown in FIG. 1 and FIG. 2, and UE 120 may be any other type of UE shown in FIG. 1. BS 110 may be equipped with antennas 334a-334t, and processors 320, 330, 338, and / or controller / processor 340 of BS 110 may be used to implement various techniques and methods described herein. For example, as shown in FIG. 3, controller / processor 340 of BS 110 includes handover manager 144, which may be configured for handover operation. For example, when the BS 110 acts as an SN, the handover manager 144 may be configured to identify a set of candidate cells for the conditional addition or change of SN for the UE based on the performance criteria. The handover manager 144 may also be configured to signal configuration information regarding the set of candidate cells to the MN. In another example, when the BS 110a acts as an MN, the handover manager 144 may be configured to receive signaling from the SN that identifies a set of candidate cells for the conditional addition or change of SN for the UE based on the performance criteria. The handover manager 144 may also be configured to signal configuration information regarding the set of candidate cells to the UE.

[0049]

[0060] Similarly, the UE 120 includes a processor 380 that includes a handover manager 142 that may be configured to receive configuration information identifying a set of candidate cells for a conditional addition or change of a secondary node (SN) for the UE based on an execution criterion. The handover manager 142 may also be configured to detect whether the execution criterion is met for one of the candidate cells. If the execution criterion is met for one of the candidate cells, the handover manager 142 may also be configured to perform a conditional addition or change as a SN for the candidate cell based on the detection.

[0050]

[0061] At the BS 110, the transmit processor 320 may receive data from the data source 312 and control information from the controller / processor 340. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH), etc. The data may be for a physical downlink shared channel (PDSCH), etc. The processor 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 320 may also generate reference symbols, e.g., for primary synchronization signaling (PSS), secondary synchronization signaling (SSS), and cell-specific reference signals (CRS). The transmit (TX) MIMO processor 330 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, and / or reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 332a-332t. Each modulator 332 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 332 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. DL signals from modulators 332a through 332t may be transmitted via antennas 334a through 334t, respectively.

[0051]

[0062] At the UE 120, the antennas 352a-352r may receive the downlink signals from the BS 110 and may provide received signals to demodulators (DEMODs) 354a-354r, respectively. Each demodulator 354 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 354 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 356 may obtain received symbols from all demodulators 354a-354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 358 may process (e.g., demodulate, deinterleave, and decode) the detected symbols and provide decoded data for the UE 120 to a data sink 360 and provide decoded control information to the controller / processor 380.

[0052]

[0063] On the UL, at the UE 120, a transmit processor 364 may receive and process data from a data source 362 (e.g., for the Physical Uplink Shared Channel (PUSCH)) and control information from the controller / processor 380 (e.g., for the Physical Uplink Control Channel (PUCCH)). The transmit processor 364 may also generate reference symbols for a reference signal. The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by demodulators 354a-354r (e.g., for SC-FDM, etc.), and transmitted to the BS 110. At the BS 110, the UL signal from the UE 120 may be received by the antenna 334, processed by the modulator 332, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by the UE 120. The receive processor 338 may provide the decoded data to a data sink 339 and provide the decoded control information to the controller / processor 340.

[0053]

[0064] The controllers / processors 340 and 380 may direct operation at the BS 110 and the UE 120, respectively. The memories 342 and 382 may store data and program codes for the BS 110 and the UE 120, respectively. The scheduler 344 may schedule the UE for data transmission on the DL and / or UL. The processor 340 and / or other processors and modules at the BS 110 may perform or direct execution of various processes for the techniques described herein, e.g., execution of the functional blocks illustrated in FIG. 6 and FIG. 7. The processor 380 and / or other processors and modules at the UE 120 may also perform or direct execution of the functional blocks illustrated in FIG. 8, for example.

[0054] EXAMPLE HANDOVER SCENARIOS

[0065] Some techniques and apparatus described herein provide low or zero latency handover from a source base station (BS) to a target BS (e.g., in a network such as a 4G / LTE or 5G / NR network). For example, some techniques and apparatus described herein provide configuration of the handover using a first protocol stack of a user equipment (UE) and a second protocol stack of the UE, where the first protocol stack is used for communication with the first BS and the second protocol stack is used for communication with the second BS. The use of two protocol stacks may allow configuration of the handover for the target BS to be performed while communication with the source BS is ongoing. Thus, latency associated with handing over a UE from a source BS to a target BS is reduced. Additionally, some techniques and apparatus described herein may provide buffering and backhauling of UE traffic between the source BS and the target BS such that the flow of traffic to the UE is not interrupted (or interruptions are reduced or minimized), thereby further reducing latency associated with handing over the UE. In this way, in the event of a handover of the UE, service levels at the UE can be met, which allows satisfaction of performance requirements for several types of traffic (e.g., gaming traffic, multimedia traffic, high reliability traffic, low latency traffic, etc.).

[0055]

[0066] Further, some techniques and apparatuses described herein may provide common packet data convergence protocol (PDCP) functionality for make-before-break (MBB) handover procedures, which may streamline security key management, encryption / decryption, integrity protection, integrity verification, data unit reordering / duplicate discarding, link selection logic, etc. Some techniques and apparatuses described herein provide control plane (e.g., BS, network controller, control entity, etc.) messaging and processing to support MBB handover. Some techniques and apparatuses described herein provide MBB handover using carrier aggregation (CA) multiple-input multiple-output (MIMO) techniques, where a reduced MIMO configuration is signaled to cause at least one antenna to be available for use for MBB handover. Still further, some techniques and apparatuses described herein provide role-switch-based MBB handover techniques, where a master cell group of a UE is switched from a source base station to a target base station while connections with the source base station and the target base station are active. In this manner, low or zero latency handover (and the benefits discussed above with respect to low or zero latency handover) is achieved.

[0056]

[0067] FIG. 4 is a call flow diagram illustrating an example 400 of determining a handover configuration for a handover procedure of a radio access network (RAN) according to various aspects of the present disclosure. As shown in FIG. 4, a UE 120 is handed over from a source BS 110-1 to a target BS 110-2. The UE 120 may be implemented by any UE (e.g., UE 120a) of FIG. 1, and the source BS 110-1 and the target BS 110-2 may be implemented by any BS 110 (e.g., BS 110a) of FIG. 1, or FIG. 2 (e.g., AN 208), DUs 214-248 of FIG. 4, or a TRP hosted by DUs 214-218 of FIG. 4. The handover described with respect to FIG. 4 may be intra-frequency or inter-frequency, and / or intra-CU or inter-CU.

[0057]

[0068] 4, at 405, UE 120 may establish a wireless communication connection with source BS 110-1 (hereinafter referred to as source connection). At 410, UE 120 may indicate the capabilities of UE 120 to any one or more of source BS 110-1, target BS 110-2, or another network entity, such as an AMF (e.g., AMF 204 of FIG. 2), a UPF (e.g., UPF 206 of FIG. 2), or any other CN function. For example, at 410, UE 120 may indicate that UE 120 has simultaneous transmission and reception capabilities and / or dual connectivity capabilities.

[0058]

[0069] At 415, the UE 120 may provide a measurement report to the source BS 110-1. The measurement report may be generated by the UE 120 and may indicate to the source BS 110-1 that a handover from the source BS 110-1 to the target BS 110-2 should be performed. For example, the UE 120 may perform cell quality measurements (e.g., L3 cell quality measurements) to assess the quality of the radio links between the UE 120 and one or more of the source BS 110-1 and the target BS 110-2. Thus, the measurement report may include the results of the cell quality measurements. In some examples, if the quality of the radio links between the UE 120 and the source BS 110-1 is sufficient to enable successful UL communication of the measurement report, successful receipt of the measurement report at the source BS 110-1 may indicate to the source BS 110-1 that a handover from the source BS 110-1 to the target BS 110-2 is to be performed.

[0059]

[0070] At 420 (assuming successful receipt of the measurement report at 415), the source BS 110-1 may determine a configuration for a handover procedure based at least in part on the capabilities indicated in step 2. For example, the source BS 110-1 may provide a handover request to the target BS 110-2 and receive a handover acknowledgement (ACK) from the target BS 110-2. In some aspects, the source BS 110-1 may communicate with the target BS 110-2 to determine a handover configuration for the UE 120.

[0060]

[0071] At 425, the source BS 110-1 may provide a configuration for a handover procedure to the UE 120. For example, the handover configuration may include a configuration for a handover procedure that utilizes or does not utilize the indicated capabilities of the UE 120. In some aspects, the handover configuration may indicate that a make-before-break (MBB) handover procedure and / or a DC-based MBB handover procedure is to be performed. Thus, the configuration may indicate to the UE 120 whether to maintain a radio link connection to the source BS 110-1 while and / or after the radio link connection to the target BS 110-2 is established.

[0061]

[0072] At 430, UE 120 requests to connect with target BS 110-2 (e.g., using the configuration received from source BS 110-1). For example, UE 120 may perform a random access procedure to establish a connection with target BS 110-2 (hereinafter referred to as the target connection).

[0062]

[0073] In response, target BS 110-2 may reply with an acknowledgment, at 435. UE 120 and target BS 110-2 may then establish the target connection, at 440. As evident in example 400 shown in FIG. 4, UE 120 may concurrently maintain both a source connection with source BS 110-1 and target BS 110-2 during the handover process. In such a case, UE 120 may experience reduced delay and / or minimal data interruption time (e.g., 0 ms handover) compared to previous techniques, since UE 120 maintains active connections with both source BS 110-1 and target BS 110-2 for a period of time.

[0063]

[0074] At 445, target BS 110-2 may instruct UE 120 to release the source connection between UE 120 and source BS 110-1 to complete the handover. For example, when UE 120 and / or target BS 110-2 determine that the target connection is strong enough (e.g., communication parameters measured by UE 120 and / or target BS 110-2 meet a first threshold indicating a strong connection), target BS 110-2 may send an instruction to complete the handover.

[0064]

[0075] In some aspects, the release of the source connection may not be based on an instruction from the target BS 110-2. Instead, the UE 120 may release the source connection without an instruction from the target BS 110-2 based at least in part on the establishment of the target connection (e.g., the UE 120 determines that communication parameters measured by the UE 120 meet a first threshold indicating a strong target connection). In some aspects, the UE 120 may release the source connection based on an instruction from the source BS 110-1. In such an example, the instruction may be based at least in part on receiving, by the source BS 110-1, an indication of the establishment of the target connection from the target BS 110-2 or from the UE 120.

[0065]

[0076] At 450, the UE 120 may release the source connection to the source BS 110-1. At 455, additional communication between the UE and the target BS 110-2 may occur using the target connection.

[0066]

[0077] Thus, as shown by example 400 in Figure 4, the UE may provide a capability to a BS or a network entity, and the BS may configure an MBB handover procedure for the UE to enable the UE to use the capability during the handover procedure. Thus, the UE may achieve improved performance during the handover procedure and experience minimal mobility interruption time (e.g., via a 0 ms handover) compared to a handover procedure that does not consider or utilize the UE's capability.

[0067]

[0078] As noted above, Figure 4 is provided as an example. Other examples may differ from those described with respect to Figure 4.

[0068]

[0079] 5 is a call flow diagram illustrating an example 500 of determining a handover configuration for a RAN handover procedure in accordance with various aspects of the present disclosure. More specifically, FIG. 5 illustrates an example intra-CU handover procedure using enhanced MBB handover, where both the source BS 110-1 and the target BS 110-2 are associated with the same CU 502.

[0069]

[0080] Prior to the start of the call flow, UE 120 may exchange user data (e.g., UL user data from UE 120 on a PUSCH and / or DL ​​user data received by the UE on a PDSCH) with CU 502 via source BS 110-1. At 505, UE 120 may send a measurement report to source BS 110-1.

[0070]

[0081] The generation and transmission of the measurement report of FIG. 5 may include the measurement report features described in FIG. 4. In some aspects, the UE 120 may generate and transmit the measurement report based at least in part on an event trigger (e.g., a signal measurement value meeting a threshold) associated with determining that a handover procedure should be initiated. For example, the execution criteria for the conditional SN addition may involve an inter-RAT measurement event configured to indicate whether one or more of: (i) a measured signal quality value of at least one inter-RAT neighbor is greater than a first threshold (e.g., the signal is strong enough); or (ii) a measured signal quality value of the PCell is less than a first threshold and a measured signal quality value of at least one inter-RAT neighbor (e.g., another BS or PCell at the current BS) is greater than a second threshold.

[0071]

[0082] In some examples, the UE 120 may include simultaneous transmission and reception capabilities (e.g., MBB capabilities) that enable the UE 120 to transmit and receive data and / or information concurrently during handover. In such cases, the UE 120 may establish and maintain multiple connections with multiple different BSs (e.g., with the source BS 110-1 and the target BS 110-2).

[0072]

[0083] At 510, the source BS 110-1 may send a UL radio resource control (RRC) transfer to the CU 502. In some aspects, the UL RRC transfer may include a measurement report. In an additional aspect, the UL RRC transfer may cause the CU 502 to determine a handover configuration to be used for the handover procedure for the UE 120. For example, the CU 502 may select from possible handover procedures that may be implemented by the UE 120 based at least in part on the indicated capabilities of the UE 120. In some aspects, the CU 502 may select an enhanced MBB handover procedure for the UE 120 based at least in part on the UE 120's indication of simultaneous transmit and receive capabilities.

[0073]

[0084] At 515, the CU 502 may send a UE context setup request to the target BS 110-2. In some examples, the CU 502 may send the UE context setup request, in part, to indicate to the target BS 110-2 that the UE 120 will be handed over to the target BS 110-2 during the handover procedure.

[0074]

[0085] At 520, the target BS 110-2 may respond to the UE context setup request by transmitting a UE context setup response. The target BS 110-2 may send the UE context setup response to acknowledge the request and / or to indicate its ability to support the handover procedure and to serve the UE 120 after the handover procedure.

[0075]

[0086] At 525, the CU 502 may send a DL RRC transfer to the source BS 110-1. In some aspects, the DL RRC transfer may include an RRC reconfiguration message indicating a configuration for a handover procedure in which the UE 120 should be handed over from the source BS 110-1 to the target BS 110-2.

[0076]

[0087] At 530, source BS 110-1 sends an RRC reconfiguration to UE 120. In some aspects, the RRC reconfiguration may include information identifying target BS 110-2, information identifying a handover configuration, and / or any other suitable information. In some examples, the RRC reconfiguration may include information indicating that UE 120 should perform an enhanced MBB handover procedure with target BS 110-2 using simultaneous transmission and reception capabilities of UE 120. In such a case, UE 120 may determine that it is capable of maintaining a connection with source BS 110-1 while establishing a connection with target BS 110-2.

[0077]

[0088] At 535, the UE 120 may perform a random access procedure with the target BS 110-2 (e.g., to initiate and / or establish a connection with the target BS 110-2). In some aspects, the UE 120 may continue to exchange user data (e.g., uplink user data and / or downlink user data) with the CU 502 via the source BS 110-1 during and after the random access procedure.

[0078]

[0089] At 540, the UE 120 may send an RRC reconfiguration complete message to the target BS 110-2. In some aspects, the UE 120 may use a dual protocol stack including a source protocol stack for communicating with the source BS 110-1 and a target protocol stack for communicating with the target BS 110-2. Each of these protocol stacks may include a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and / or a Physical (PHY) layer. In some aspects, the source and target protocol stacks may share one or more layers, such as a common PDCP layer or entity. In some aspects, the UE 120 may use the target protocol stack for UL data transmission.

[0079]

[0090] At 545, the target BS 110-2 may send a UL RRC transfer to the CU 502. In some examples, the UL RRC transfer may indicate that the RRC reconfiguration is complete. Thus, in some aspects, based at least in part on receiving an indication that the RRC reconfiguration is complete, the CU 502 may determine a handover completion configuration. For example, when making a completion determination, the CU 502 may utilize and / or configure one or more thresholds for one or more measurement parameters to perform a handover completion procedure (e.g., to release the source BS 110-1). Furthermore, in some aspects, after the RRC reconfiguration is complete, the UE 120 may perform uplink user / control plane replication with the source BS 110-1 and the CU 502. For example, control plane data may be replicated and shared between the BS 110-1 and the CU 502. Furthermore, in some aspects, after CU 502 determines that the RRC reconfiguration is complete, CU 502 may continue to send DL user data to UE 120 via target BS 110-2 and DL user / control plane replication to UE 120 via source BS 110-1. Thus, UE 120 may achieve improved reliability when receiving data on the downlink.

[0080]

[0091] At 550, the CU 502 may send a UE context modification request to the source BS 110-1. The UE context modification request may include a stop transmission indicator to indicate that the source BS 110-1 should be released from serving the UE 120 (e.g., release of the radio link between the source BS 110-1 and the UE 120). In some examples, the source BS 110-1 may provide a DL data delivery status to the CU 502 indicating the status of the DL user / control plane replication that the source BS 110-1 is communicating to the UE 120.

[0081]

[0092] At 555, the source BS 110-1 may send a UE context modification response to the CU 502. For example, the UE context modification response may include an acknowledgement that the source BS 110-1 should be released during the handover procedure and / or should no longer serve the UE 120.

[0082]

[0093] At 560, the CU 502 may send a DL RRC transfer to the target BS 110-2. The DL RRC transfer may include an RRC reconfiguration message indicating that a handover procedure from the source BS 110-1 to the target BS 110-2 should be performed.

[0083]

[0094] At 565, target BS 110-2 may send an RRC reconfiguration to UE 120. In some examples, the RRC reconfiguration message may indicate that UE 120 should release its connection with source BS 110-1. Accordingly, UE 120 may release its connection with source BS 110-1 based at least in part on receiving the RRC reconfiguration message. Further, UE 120 may then begin exchanging uplink and downlink user data with CU 502 via target BS 110-2.

[0084]

[0095] At 570, UE 120 may send an RRC reconfiguration complete message to target BS 110-2. The RRC reconfiguration complete message may indicate that UE 120 has released the connection with source BS 110-1.

[0085]

[0096] At 575, target BS 110-2 may send a UL RRC transfer to CU 502. In some aspects, the UL RRC transfer may occur in response to receiving an RRC reconfiguration complete message, which may indicate that an RRC reconfiguration complete message has been received from UE 120.

[0086]

[0097] At 580, the CU 502 may then send a UE context release command to the source BS 110-1 (eg, so that the source BS 110-1 does not continue attempting to serve the UE 120).

[0087]

[0098] At 585, the source BS 110-1 may send a UE context release complete message to the CU 502. The UE context release complete message may be an acknowledgement that the source BS 110-1 is no longer in communication with and / or serving the UE 120.

[0088]

[0099] As noted above, Figure 5 is provided as an example. Other examples may differ from those described with respect to Figure 5.

[0089] Exemplary Optimizations for Enhanced Handover (HO) Procedures Using Aspects of Conditional Handover (CHO)

[0100] Aspects of the present disclosure relate to wireless communications, and more particularly, to an enhanced handover (HO) procedure configured to improve make-before-break (MBB) and conditional handover (CHO) procedures. In some cases, the optimization may support MBB and / or CHO procedures with N2 signaling. In some cases, the optimization may include taking action to prioritize handover procedures to target base stations (BSs) that may be able to utilize an Xn connection.

[0090]

[0101] N2 signaling generally refers to signaling over the physical N2 interface between an NG-RAN g Node B (gNB) and an Access and Mobility Management Function (AMF) and the logical N1 interface between a user equipment (UE) and the AMF in a 5G Core (5GC) network. N2 generally serves as a control plane interface between an access network (NG-RAN or non-3GPP wireless local area network (WLAN)) and a 5GC network. N2 generally relates to connection management, UE context and protocol data unit (PDU) session management, and UE mobility management. Xn signaling generally refers to signaling using the Xn interface that exists between base stations (e.g., between gNBs). Xn generally refers to the network interface between NG-RAN nodes.

[0091]

[0102] The techniques presented herein may help provide optimizations to support MBB and CHO for NG inter-RAN handovers. In some cases of enhanced handover procedures, the source BS and the target BS are connected via Xn, which provides a relatively low latency communication interface. In such cases, data forwarding may be communicated between these nodes over Xn. Thus, aspects of the present disclosure may enable the N2-based HO procedure to prioritize such nodes to take advantage of the lower latency associated with Xn signaling.

[0092]

[0103] Generally, the CHO configuration is sent to the UE before the actual HO event. The source BS may prepare one or more candidate target cells for CHO. For each candidate target cell, the network (e.g., source BS and / or CN) configures the UE with information to enable the UE to connect to the target cell during HO and conditions to trigger HO to the target cell. When the HO conditions are met, the UE initiates a random access procedure (RACH) with the target cell. In such a case, the UE does not need to send a measurement report or wait for an RRC reconfiguration to perform HO.

[0093]

[0104] As mentioned above, in the CHO procedure defined for N2-based candidate cell preparation, the source BS may prepare and / or select candidate cells based on metrics alone. If some of the cells belong to different AMFs, there may be benefits in optimizing the source BS and UE CHO execution logic to prioritize cells that use the same AMF. In some cases, data forwarding over N2 may benefit from optimization of when to enable data forwarding for MBB and / or CHO handover procedures.

[0094] A conditional procedure for adding and modifying secondary nodes (SNs) initiated by the SN

[0105] Aspects of the present disclosure provide techniques that may help optimize / improve enhanced handover (HO) procedures, such as make-before-break (MBB) and conditional handover (CHO).

[0095]

[0106] As described, CHO is a HO procedure in which a user equipment (UE) selects a target cell for HO among candidate target cells based on CHO execution criteria. As described herein, the CHO procedure may be implemented for secondary node (SN) addition or modification procedures and may reduce delays involved in SN addition or modification in dual connectivity scenarios.

[0096]

[0107] In the case of a conditional primary secondary cell (PSCell) change, various scenarios for SN change may include a master node (MN)-initiated SN change and an SN-initiated SN change. As the name suggests, in an MN-initiated SN change, the MN generally determines which PSCells may be configured as candidate PSCells as well as the execution criteria and performs an SN addition procedure with the candidate SNs. Alternatively, in an SN-initiated SN change, the SN generally determines which PSCells may be configured as candidate PSCells and performs an SN addition procedure with the candidate SNs. In some cases, an SN-initiated SN change may involve the SN determining the execution criteria.

[0097]

[0108] 6, 7, and 8 are flow diagrams illustrating example operations for an SN-initiated SN change procedure that may be performed by a BS acting as an SN (e.g., any type of BS shown in FIG. 1, FIG. 2, or FIG. 3), a BS acting as an MN (e.g., any type of BS shown in FIG. 1, FIG. 2, or FIG. 3), and a UE (e.g., any type of UE shown in FIG. 1 or FIG. 3), respectively.

[0098]

[0109] FIG. 6 illustrates example operations 600 that may be performed by a secondary node (SN) according to some aspects of the disclosure. The operations 600 may be performed, for example, by a BS (e.g., BS 110 shown in FIG. 1, FIG. 2, or FIG. 3) serving and / or serving as an SN. The operations 600 may be complementary to the operations 700 performed by an MN and / or the operations 800 performed by a UE, described below with respect to FIG. 7 and FIG. 8. The operations 600 may be implemented as software components that execute and operate on one or more processors (e.g., controller / processor 340 of FIG. 3). Furthermore, the transmission and reception of signals by the SN in the operations 600 may be enabled, for example, by one or more antennas (e.g., antenna 334 of FIG. 3). In some aspects, the transmission and / or reception of signals by the SN may be implemented via a bus interface of one or more processors (e.g., controller / processor 340) that acquires and / or outputs signals.

[0099]

[0110] The operations 600 begin with the SN identifying a set of one or more candidate cells for conditional addition or change of SN for the UE based on performance criteria at block 602. At block 604, the SN signals information regarding the set of candidate cells to the MN.

[0100]

[0111] FIG. 7 illustrates example operations 700 that may be performed by a master node (MN) according to some aspects of the disclosure. The operations 700 may be performed, for example, by a BS (e.g., BS 110 shown in FIG. 1, FIG. 2, or FIG. 3, or one or more of its processors shown in FIG. 3) serving the MN. The operations 700 may be complementary to the operations 600 performed by an SN and / or the operations 800 performed by a UE described with respect to FIG. 6 and FIG. 8. The operations 700 may be implemented as software components that execute and operate on one or more processors (e.g., controller / processor 340 of FIG. 3). Furthermore, the transmission and reception of signals by the MN in the operations 700 may be enabled, for example, by one or more antennas (e.g., antenna 334 of FIG. 3). In some aspects, the transmission and / or reception of signals by the MN may be implemented via a bus interface of one or more processors (e.g., controller / processor 340) that acquires and / or outputs signals.

[0101]

[0112] The operations 700 may begin by receiving signaling from an SN identifying a set of candidate cells for conditional addition or modification of the SN for the UE based on performance criteria, at block 702. At block 604, the MN signals configuration information regarding the set of candidate cells to the UE.

[0102]

[0113] FIG. 8 illustrates example operations 800 that may be performed by a UE according to some aspects of the disclosure. The operations 800 may be performed by a UE participating in a procedure with a MN and a SN, such as, for example, the UE 120 (or one or more of its processors shown in FIG. 3) shown in FIG. 1 and FIG. 3. The operations 800 may be supplemental to the operations 600 performed by the SN and / or the operations 700 performed by the MN described with respect to FIG. 6 and FIG. 7. The operations 800 may be implemented as software components that execute and operate on one or more processors (e.g., the controller / processor 380 of FIG. 3). Furthermore, the transmission and reception of signals by the UE in the operations 800 may be enabled, for example, by one or more antennas (e.g., the antenna 352 of FIG. 3). In some aspects, the transmission and / or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., the controller / processor 380) that acquires and / or outputs the signals.

[0103]

[0114] The operations 800 begin at block 802 by the UE receiving configuration information from the MN that identifies a set of candidate cells for conditional addition or change of SN for the UE based on an execution criterion. At block 804, the UE detects that the execution criterion is met for one of the candidate cells. At block 806, the UE takes action to add or change as SN to the candidate cell based on the detection.

[0104]

[0115] As described above, the UE 120 may be configured with conditional PSCell execution criteria for SN addition and modification procedures. The measurement events used to trigger the PSCell addition and / or PSCell modification may differ based on the type of dual connectivity architecture. Moreover, the measurement events may be independently configured by the MN 110a and the SN. Therefore, the conditional PSCell addition / modification RRC message must support configuring a separate execution criteria configuration for each PSCell of multiple PSCells to enable the UE 120 to perform the PSCell addition and / or PSCell modification.

[0105]

[0116] For conditional PSCell addition and / or change, various options exist for supporting SN-initiated SN change. In some aspects, for an SN-triggered SN change, the SN may identify a set of one or more PSCells that may be configured as candidate cells, and the MN determines the execution criteria for the candidate cells. In some aspects, for an SN-triggered SN change, the SN may both identify a set of one or more PSCells that may be configured as candidate cells and determine the execution criteria for the candidate cells.

[0106]

[0117] FIG. 9 illustrates a diagram of a first call flow 900 illustrating example communications between a UE, a MN, and a SN according to various aspects of the present disclosure. As illustrated in the first option illustrated by FIG. 9, the SN may identify a set of one or more PSCells that may be configured as candidate cells, and the MN determines the execution criteria for the candidate cells. Upon determination of a triggering event, the UE 120 may decide to fall back to communication with the SN 110a (e.g., the BS 110a of FIG. 1). For example, the triggering event may include detection by the UE 120 of a HO failure (e.g., T304 expiration) or a radio link failure (RLF) on the SN connection while the UE 120 is still connected to the SN 110a (e.g., the source cell is active). In this example, the UE 120 may declare an RLF on the SN connection and operate using the existing SN 110a connection, but refrain from triggering a radio resource control (RRC) re-establishment.

[0107]

[0118] Before and during the triggering event, UE 120 may monitor neighboring cells. In the example of FIG. 9, the neighboring cells may include a first candidate secondary node (CSN1) and a second candidate secondary node (CSN2) (e.g., BS 110c and BS 110d, respectively). In response to the triggering event, UE 120 may send a measurement report identifying CSN1 and CSN2 to MN 110b, which was configured for measurement in step 1. MN 110b may then forward the measurement report to SN 110a. The measurement report may be generated by UE 120 and may indicate to MN 110b and SN 110a that UE 120 is requesting a CHO to a new or additional SN.

[0108]

[0119] Based on the received measurement report, the SN may decide which of the candidate cells should be configured as a new PSCell for the UE 120 (e.g., CSN1 and CSN2 in this example). After identifying the set of candidate cells for the SN list, the SN 110a may initiate the conditional SN change in step 2 by sending a candidate SN addition list including both CSN1 and CSN2 to the MN 110b in an XN message.

[0109]

[0120] As shown, MN 110b may perform an SN addition procedure using the candidate SN. In step 3, MN 110b may transmit a first conditional SN addition message (e.g., an SN addition request to CSN1) to initiate a first conditional SN addition procedure with CSN1. In step 4, MN 110b may receive an SN addition acknowledgment transmitted by CSN1.

[0110]

[0121] In step 5, MN 110b may send a second conditional SN addition message (e.g., an SN addition request to CSN2) to initiate a second conditional SN addition procedure with CSN2. In step 6, MN 110b may receive the SN addition acknowledgment sent by CSN2.

[0111]

[0122] MN 110b may also determine performance criteria for each candidate SN, where the performance criteria provide the criteria by which the performance of an addition or modification (e.g., HO) of a particular one of CSN1 110b or CSN2 110c should be performed.

[0112]

[0123] In some aspects, the UE 120, the MN 110b, and the SN 110a may support the use of the A3 / A5 event execution criteria for conditional NR PSCell addition execution conditions.

[0113]

[0124] In step 7, MN 100b may send the execution condition (e.g., execution criteria) and the candidate SN list to UE 120 in an RRC configuration message (e.g., an “RRC reconfiguration message” for NR) to UE 120. In some examples, the RRC configuration message may configure UE 120 for multiple candidate SNs in a single message. For example, the RRC configuration message may include configuration information for both CSN1 and CSN2. In some examples, the RRC configuration message may include one or more of: (i) source cell RRC configuration changes (if any); (ii) conditional SN addition or change execution criteria for each candidate cell in the set (configured by MN 110b); and / or (iii) RRC reconfiguration for each CSN.

[0114]

[0125] After receiving the RRC configuration message, UE 120 may monitor the conditions for changing the PSCell based on the configuration received from the MN.

[0115]

[0126] For example, UE 120 may determine whether the quality of the neighbor cell is greater than a threshold of an execution criterion that MN 110b sent to UE 120. If UE 120 determines that the quality is greater than the threshold, the execution criterion is met. In the case of CHO, instead of UE 120 sending a measurement report to MN 110b (which may be forwarded to SN 110a), the UE may determine that the execution criterion for the candidate PSCell (e.g., B1 event criterion or A3 / A5 event criterion) is met, and UE 120 may perform a handover to the candidate PSCell.

[0116]

[0127] As shown, if SN 110a decides to change the candidate SN list, SN 110a may initiate another conditional SN change by sending a new candidate SN addition list to MN 110b in an Xn message in step 8. Because UE 120 channel conditions are constantly changing, UE 120 may send a subsequent measurement report after some time. The new measurement report (e.g., the measurement report sent at time t2) may differ from the measurement report sent in step 1 (i.e., the measurement report sent at time t1). Thus, the new measurement report may indicate to the SN that some candidate cells may no longer be suitable for the candidate SN list.

[0117]

[0128] 9, SN 110a may decide to release CSN2 and include only CSN1 in the SN addition list. Thus, in step 9, MN 110b may transmit a candidate addition / release list to UE 120. Furthermore, MN 110b may perform an SN release procedure with CSN2 in steps 10 and 11.

[0118]

[0129] 10 illustrates a second call flow diagram 1000 illustrating example communications between a UE, a MN, and a SN in accordance with various aspects of the present disclosure. As illustrated in the first option illustrated by FIG. 9, the SN may both identify a set of one or more PSCells that may be configured as candidate cells and determine performance criteria for the candidate cells.

[0119]

[0130] Similar to FIG. 9, a triggering event (e.g., HO failure or RLF) may cause UE 120 to send a measurement report identifying CSN1 and CSN2 to MN 110b configured for measurements in step 1, which MN 110b may forward to SN 110a. SN 110a may select candidate cells (again CSN1 and CSN2) based on the measurement report for a candidate SN list. Again, in step 2, SN 110a may send the candidate SN list to MN 110b in an Xn message, so that MN 110b may perform an SN addition procedure (in steps 3-6).

[0120]

[0131] Unlike the example shown in Fig. 9, the SN 110a in Fig. 10 may also determine an execution criterion for the candidate cell and signal information regarding the execution criterion to the MN 110b. The MN 110b may include the execution criterion in an RRC reconfiguration message sent to the UE 120 in step 7. There may be various options for sending the execution criterion from the SN 110a to the MN 110b.

[0121]

[0132] In some examples, the RRC message may include an execution criteria configuration for each candidate cell in a transparent container. In some examples, the RRC message may include an RRC reconfiguration for each candidate cell in the set in a transparent container.

[0122]

[0133] In some examples, according to the first option, the MN 110b may be enabled to modify the performance criteria in the Xn message from the SN 110a to the MN 110b. Thus, the RRC message sent by the MN 110b to the UE 120 may signal information regarding the candidate cells and the modified performance criteria (similar to the option shown in FIG. 9).

[0123]

[0134] In some examples, according to the second option, as shown in step 2 of Figure 10, SN 110a may include the conditional SN change execution criteria in the SN-to-MN transparent container so that MN 110b may change it. In this case, MN 110b may simply forward the container to the UE (without modification) with the SN-defined execution criteria and the candidate SN reconfiguration in the RRC reconfiguration message sent by MN 110b to UE 120.

[0124]

[0135] In some examples where a UE is configured with conditional SN change configurations from both MN 110b and SN 110a, UE 120 may monitor both configurations independently. Thus, UE 120 may trigger an SN change when either the MN-defined or SN-defined performance criteria are met (e.g., based on whichever condition occurs first).

[0125]

[0136] In some aspects, after performing a SN change to a new SN (e.g., CSN1 or CSN2), UE 120 may stop monitoring the execution conditions (e.g., criteria) configured by old SN 110a. In such a case, UE 120 may notify MN 110b about the SN change (e.g., via an RRC reconfiguration complete message). In response, MN 110b may clean up the old SN selected candidate SN configuration. For example, MN 110b may remove old candidate cells if they are no longer suitable as candidate SNs.

[0126]

[0137] 11 illustrates a communications device 1100 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as those illustrated in FIG. 6. The communications device 1100 includes a processing system 1102 coupled to a transceiver 1108. The transceiver 1108 is configured to transmit and receive signals for the communications device 1100 via an antenna 1110, such as various signals described herein. The processing system 1102 may be configured to perform processing functions for the communications device 1100, including processing signals received and / or to be transmitted by the communications device 1100.

[0127]

[0138] The processing system 1102 includes a processor 1104 coupled to a computer-readable medium / memory 1112 via a bus 1106. In some aspects, the computer-readable medium / memory 1112 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1104, cause the processor 1104 to perform the operations illustrated in FIG. 6 or other operations for implementing various techniques described herein. In some aspects, the computer-readable medium / memory 1112 stores code 1114 for identifying (e.g., for identifying a set of one or more candidate cells for conditional addition or modification of a SN for a UE based on an execution criterion) and code 1116 for signaling (e.g., for signaling information regarding the set of candidate cells to the MN). In some aspects, the processor 1104 has circuitry configured to implement the code stored in the computer-readable medium / memory 1112. The processor 1104 includes a circuit 1124 for identifying (e.g., for identifying a set of one or more candidate cells for conditional addition or modification of an SN for a UE based on an execution criterion) and a circuit 1126 for signaling (e.g., for signaling information regarding the set of candidate cells to the MN).

[0128]

[0139] 12 shows a communications device 1200 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as those illustrated in FIG. 7. The communications device 1200 includes a processing system 1202 coupled to a transceiver 1208. The transceiver 1208 is configured to transmit and receive signals for the communications device 1200 via an antenna 1210, such as various signals described herein. The processing system 1202 may be configured to perform processing functions for the communications device 1200, including processing signals received and / or to be transmitted by the communications device 1200.

[0129]

[0140] The processing system 1202 includes a processor 1204 coupled to a computer-readable medium / memory 1212 via a bus 1206. In some aspects, the computer-readable medium / memory 1212 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1204, cause the processor 1204 to perform the operations illustrated in FIG. 7 or other operations for implementing various techniques described herein. In some aspects, the computer-readable medium / memory 1212 stores code 1214 for receiving (e.g., for receiving signaling from an SN identifying a set of candidate cells for conditional addition or modification of the SN for the UE based on an execution criterion) and code 1216 for signaling (e.g., for signaling configuration information regarding the set of candidate cells to the UE). In some aspects, the processor 1204 has circuitry configured to implement the code stored in the computer-readable medium / memory 1212. Processor 1204 includes a circuit 1224 for receiving (e.g., for receiving signaling from an SN identifying a set of candidate cells for conditional addition or modification of the SN for the UE based on an execution criterion) and a circuit 1226 for signaling (e.g., for signaling configuration information regarding the set of candidate cells to the UE).

[0130]

[0141] 13 shows a communications device 1300 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as those illustrated in FIG. 8. The communications device 1300 includes a processing system 1302 coupled to a transceiver 1308. The transceiver 1308 is configured to transmit and receive signals for the communications device 1300 via an antenna 1310, such as various signals described herein. The processing system 1302 may be configured to perform processing functions for the communications device 1300, including processing signals received and / or to be transmitted by the communications device 1300.

[0131]

[0142] The processing system 1302 includes a processor 1304 coupled to a computer-readable medium / memory 1312 via a bus 1306. In some aspects, the computer-readable medium / memory 1312 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1304, cause the processor 1304 to perform the operations illustrated in FIG. 8 or other operations for implementing various techniques described herein. In some aspects, the computer-readable medium / memory 1312 stores code 1314 for receiving (e.g., for receiving configuration information from a MN identifying a set of candidate cells for conditional addition or modification of an SN for a UE based on an execution criterion), code 1316 for detecting (e.g., for detecting that the execution criterion is met for one of the candidate cells), and code 1318 for taking an action (e.g., for taking an action to add or modify as an SN for a candidate cell based on the detection). In some aspects, the processor 1304 has circuitry configured to implement the codes stored in the computer-readable medium / memory 1312. The processor 1304 includes a circuit 1324 for receiving (e.g., for receiving configuration information from the MN identifying a set of candidate cells for conditional addition or modification of an SN for the UE based on an execution criterion), a circuit 1326 for detecting (e.g., for detecting that the execution criterion is met for one of the candidate cells), and a circuit 1328 for taking action (e.g., for taking action to add or modify as an SN for the candidate cell based on the detection).

[0132] Example Aspects

[0143] Aspect 1. A method for wireless communication by a user equipment (UE), comprising: receiving, from a master node (MN), configuration information identifying a set of candidate cells and an execution criterion for conditional addition or change of a secondary node (SN) for the UE; detecting that the execution criterion is met for one of the candidate cells; and taking action to add or change the candidate cell as an SN based on the detection.

[0133]

[0144] Aspect 2. The method of aspect 1, wherein the configuration information is received by the UE in a radio resource control (RRC) message.

[0134]

[0145] Aspect 3. The method of aspect 2, wherein the RRC message includes at least one of the following information for conditional addition or modification of an SN: a source cell RRC configuration change, a conditional SN addition or modification execution criteria configuration for each candidate cell in the set, or an RRC reconfiguration for each candidate cell in the set.

[0135]

[0146] Aspect 4. The method of aspect 3, wherein the RRC message includes an execution criteria configuration for each candidate cell in a transparent container.

[0136]

[0147] Aspect 5. The method of any of aspects 1 to 4, further comprising: sending a radio resource control (RRC) message to the MN indicating when a conditional SN addition or modification execution criterion is met for a selected one of the candidate cells in the set if the configuration of the selected cell is valid.

[0137]

[0148] Aspect 6. The method of any of aspects 1 to 5, wherein the configuration information indicates first configuration information determined by the MN and second configuration information determined by the SN, and the UE independently monitors the performance criteria according to the first configuration and the performance criteria according to the second configuration, and performs an SN change for the candidate cell when either the performance criteria according to the first configuration or the performance criteria according to the second configuration is satisfied.

[0138]

[0149] Aspect 7. The method of aspect 6, wherein the UE stops monitoring the performance criteria determined by the old SN after performing the SN change to the candidate cell.

[0139]

[0150] Example 8. The method of example 6 or 7, further comprising sending a notification to the MN indicating that a SN change to the candidate cell has been performed.

[0140]

[0151] Aspect 9. The method of aspect 8, wherein the notification is sent via a radio resource control (RRC) reconfiguration complete message.

[0141]

[0152] Aspect 10. A method for wireless communication by a secondary node (SN), comprising: identifying a set of one or more candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; and signaling information regarding the set of candidate cells to a master node (MN).

[0142]

[0153] Aspect 11. The method of aspect 10, wherein information regarding a set of candidate cells is signaled to the MN via a message without execution criteria, and the MN determines execution criteria for the candidate cells and signals the candidate cells and the execution criteria to the UE.

[0143]

[0154] Example 12. The method of example 10 or 11, further comprising: determining an execution criterion for the candidate cell; and signaling information regarding the execution criterion to the MN.

[0144]

[0155] Aspect 13. The method of aspect 12, wherein the MN is enabled to modify performance criteria for candidate cells and to signal information regarding the candidate cells and the modified performance criteria to the UE.

[0145]

[0156] Aspect 14. The method of aspect 12 or 13, wherein the SN signals to the MN information regarding the execution criteria, which should be forwarded to the UE without modification.

[0146]

[0157] Aspect 15. The method of aspect 14, in which the SN signals information regarding the execution criteria in a transparent container, and the MN forwards the transparent container to the UE.

[0147]

[0158] Example 16. The method of any of examples 10 to 15, further comprising: deciding to change the set of one or more candidate cells; and signaling information regarding the change to the MN.

[0148]

[0159] Aspect 17. A method for wireless communication by a master node (MN), comprising: receiving signaling from a secondary node (SN) identifying a set of candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; and signaling configuration information regarding the set of candidate cells to the UE.

[0149]

[0160] Aspect 18. The method of aspect 17, in which the MN receives information regarding a set of candidate cells from the SN via a message without execution criteria, the MN determines execution criteria for the candidate cells, and signals the candidate cells and the execution criteria to the UE.

[0150]

[0161] Example 19. The method of example 17 or 18, further comprising receiving information regarding performance criteria for candidate cells from an SN.

[0151]

[0162] Aspect 20. The method of aspect 19, further comprising: modifying performance criteria for the candidate cells; and signaling information regarding the candidate cells and the modified performance criteria to the UE.

[0152]

[0163] Aspect 21. The method of aspect 20, in which the SN signals information regarding the performance criteria to the MN, which should be forwarded to the UE without modification, and the MN forwards the information regarding the performance criteria to the SN without modification.

[0153]

[0164] Aspect 22. The method of aspect 21, in which the SN signals information regarding the execution criteria in a transparent container, and the MN forwards the transparent container to the UE.

[0154]

[0165] Example 23. The method of any of examples 17 to 22, further comprising performing an SN addition procedure with the candidate cell.

[0155]

[0166] Example 24. The method of any of examples 17 to 23, wherein the configuration information is signaled to the UE in a radio resource control (RRC) message.

[0156]

[0167] Example 25. The method of any of examples 17-24, further comprising receiving, for a selected one of the candidate cells in the set, a radio resource control (RRC) message from the UE indicating when a conditional SN addition or modification execution criterion is met if the configuration of the selected cell is valid.

[0157]

[0168] Example 26. The method of any of examples 17 to 25, wherein the configuration information is signaled to the UE in a radio resource control (RRC) message that includes separate execution criteria for conditional SN addition and SN change.

[0158]

[0169]

[0031] Aspect 27. The method of any of aspects 17 to 26, further comprising: receiving a notification from a UE regarding a change in SN via a radio resource control (RRC) reconfiguration complete message; and updating a candidate SN configuration to remove cells that are no longer suitable candidate cells for conditional addition or change as an SN.

[0159]

[0170] Aspect 28. An apparatus for wireless communication by a user equipment (UE), comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: receive configuration information from a master node (MN) identifying a set of candidate cells for conditional addition or modification of a secondary node (SN) for the UE based on an execution criterion; detect that the execution criterion is met for one of the candidate cells; and take action to add or modify the candidate cell as an SN based on the detection.

[0160]

[0171] Aspect 29. An apparatus for wireless communication by a secondary node (SN), comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: identify a set of one or more candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; and signal information regarding the set of candidate cells to a master node (MN).

[0161]

[0172] Aspect 30. An apparatus for wireless communication by a master node (MN), comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: receive signaling from a secondary node (SN) identifying a set of candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; and signal configuration information regarding the set of candidate cells to the UE.

[0162] Additional Considerations

[0173] The methods disclosed herein comprise one or more steps or actions for achieving the described method. The steps and / or actions of the methods may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0163]

[0174] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to encompass a, b, c, ab, ac, bc, and abc, as well as any combination with multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other permutation of a, b, and c).

[0164]

[0175] The term "determining" as used herein encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" may include resolving, selecting, choosing, establishing, and the like.

[0165]

[0176] The above description is provided to enable those skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Thus, the claims are not limited to the embodiments set forth herein, but are to be accorded the full scope consistent with the language of the claims, in which reference to an element in the singular does not mean "one and only," unless so expressly stated, but rather means "one or more." Unless otherwise expressly stated, the term "some" refers to one or more. All structural and functional equivalents of the elements of the various embodiments described throughout this disclosure that are known or that later become known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is made public, regardless of whether such disclosure is expressly recited in the claims. No claim element is to be construed under 35 U.S.C. ...

[0166]

[0177] The various operations of the methods described above may be performed by any suitable means capable of performing the corresponding functions. Those means may include various (one or more) hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. Generally, where there are operations illustrated in the figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

[0167]

[0178] The various example logic blocks, modules, and circuits described in connection with this disclosure may be implemented or performed using a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0168]

[0179] When implemented in hardware, an exemplary hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented using a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the particular application and overall design constraints of the processing system. The bus may link various circuits together, including the processor, the machine-readable medium, and the bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1), a user interface (e.g., keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, etc., which are well known in the art and therefore will not be described further. The processor may be implemented using one or more general-purpose and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. Those skilled in the art will understand how to best implement the described functionality for a processing system depending on the particular application and the overall design constraints imposed on the overall system.

[0169]

[0180] If implemented in software, the functions may be stored on or transmitted over a computer-readable medium as one or more instructions or code. Software should be broadly construed to mean instructions, data, or any combination thereof, whether termed software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media includes both computer storage media and communication media, including any medium that enables transfer of a computer program from one place to another. A processor may be responsible for managing a bus and general processing, including the execution of software modules stored in a machine-readable storage medium. A computer-readable storage medium may be coupled to a processor such that the processor can read information from the storage medium and write information to the storage medium. Alternatively, the storage medium may be integral to the processor. By way of example, a machine-readable medium may include a transmission line, a carrier wave modulated by data, and / or a computer-readable storage medium having instructions stored thereon separate from a wireless node, all of which may be accessed by a processor via a bus interface. Alternatively or additionally, the machine-readable medium, or any portion thereof, may be integrated into the processor, such as may be a cache and / or a general-purpose register file. Examples of machine-readable storage media may include, by way of example, a RAM (random access memory), a flash memory, a ROM (read-only memory), a PROM (programmable read-only memory), an EPROM (erasable programmable read-only memory), an EEPROM (electrically erasable programmable read-only memory), a register, a magnetic disk, an optical disk, a hard drive, or other suitable storage media, or any combination thereof. The machine-readable medium may be embodied in a computer program product.

[0170]

[0181] A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. A computer-readable medium may comprise several software modules. A software module includes instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a transmitting module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. As an example, a software module may be loaded from a hard drive into RAM when a triggering event occurs. During execution of a software module, a processor may load some of the instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general-purpose register file for execution by the processor. When referring to a function of a software module below, it will be understood that such function is implemented by a processor when executing instructions from that software module.

[0171]

[0182] Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically and discs reproduce data optically with lasers. Thus, in some aspects computer-readable medium may comprise non-transitory computer-readable medium (e.g., tangible media). Additionally, in other aspects computer readable media may comprise transitory computer readable media (eg, a signal). Combinations of the above should also be included within the scope of computer readable media.

[0172]

[0183] Accordingly, some aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having stored thereon (and / or encoded thereon) instructions executable by one or more processors to perform the operations described herein.

[0173]

[0184] It should further be appreciated that modules and / or other suitable means for implementing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or base station, where applicable. For example, such devices may be coupled to a server to enable transfer of means for implementing the methods described herein. Alternatively, the various methods described herein may be provided by a storage means such that the user terminal and / or base station may obtain the various methods upon coupling or providing the storage means (e.g., RAM, ROM, physical storage medium such as a compact disk (CD) or floppy disk, etc.) to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device may be utilized. It should be understood that the claims are not limited to the precise configuration and components shown above. Various modifications, changes and variations may be made in the configuration, operation and details of the methods and apparatus described above without departing from the scope of the claims. The invention as described in the claims of the original application is set forth below. [C1] A method for wireless communication by a user equipment (UE), comprising: receiving configuration information and performance criteria from a master node (MN) identifying a set of candidate cells for conditional addition or modification of a secondary node (SN) for the UE; detecting that the performance criteria is met for one of the candidate cells; and taking action to add or modify the candidate cell as a SN based on the detection. A method comprising: [C2] The configuration information is received by the UE in a radio resource control (RRC) message. The method according to C1. [C3] The RRC message contains the following information for conditional addition or modification of SN: Source cell RRC configuration change, configuring a conditional SN addition or modification execution criterion for each candidate cell in the set; or an RRC reconfiguration for each candidate cell in the set; The method of claim 2, comprising at least one of: [C4] The method according to C3, wherein the RRC message includes the execution criteria configuration for each candidate cell in a transparent container. [C5] The method of C1, further comprising: sending a radio resource control (RRC) message to the MN indicating when the conditional SN addition or modification execution criteria is met for a selected one of the candidate cells in the set if the configuration of the selected cell is valid. [C6] The configuration information indicates first configuration information determined by the MN and second configuration information determined by the SN; The UE independently monitors a performance criterion according to the first configuration and a performance criterion according to the second configuration; performing an SN change for a candidate cell when either the performance criterion according to the first configuration or the performance criterion according to the second configuration is satisfied. The method according to C1. [C7] The method according to C6, wherein the UE stops monitoring the execution criteria determined by an old SN after performing the SN change to the candidate cell. [C8] The method of C6, further comprising sending a notification to the MN indicating that the SN change to a candidate cell has been performed. [C9] The method of C8, wherein the notification is sent via a radio resource control (RRC) reconfiguration complete message. [C10] A method for wireless communication by a secondary node (SN), comprising: identifying a set of one or more candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; and signaling information regarding the set of candidate cells to a master node (MN). [C11] The information regarding the set of candidate cells is signaled to the MN via a message without execution criteria; the MN determines the performance criteria for the candidate cell and signals the candidate cell and the performance criteria to the UE; The method according to C10. determining a performance criterion for the candidate cell; and signaling information regarding said performance criteria to said MN; The method of C10, further comprising: [C13] The method of C12, wherein the MN is enabled to modify the performance criteria for the candidate cells and to signal information regarding the candidate cells and the modified performance criteria to the UE. [C14] The SN signals to the MN the information on the performance criteria to be forwarded to the UE without modification. The method according to C12. [C15] The SN signals the information regarding the performance criteria in a transparent container; The method according to C14, wherein the MN forwards the transparent container to the UE. [C16] deciding to change said set of one or more candidate cells; signaling information regarding the change to the MN; The method of C10, further comprising: [C17] A method for wireless communication by a master node (MN), comprising: receiving signaling from a secondary node (SN) identifying a set of candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; signaling configuration information regarding the set of candidate cells to the UE; A method comprising: [C18] the MN receives the information on the set of candidate cells from the SN via a message without execution criteria; the MN determines the performance criteria for the candidate cell and signals the candidate cell and the performance criteria to the UE; The method according to C17. receiving information regarding performance criteria for the candidate cells from the SN; The method of C17, further comprising: [C20] modifying the performance criteria for the candidate cells; and signaling information regarding the candidate cells and the modified performance criteria to the UE; The method of C19, further comprising: [C21] The SN signals to the MN the information on the performance criteria to be forwarded to the UE without modification; the MN forwards, without modification, the information regarding the performance criteria to the SN; The method according to C19. [C22] The SN signals the information regarding the performance criteria in a transparent container; The method according to C21, wherein the MN forwards the transparent container to the UE. [C23] The method of C17, further comprising performing an SN addition procedure using the candidate cell. [C24] The method of C17, wherein the configuration information is signaled to the UE in a radio resource control (RRC) message. [C25] The method of C17, further comprising receiving a radio resource control (RRC) message from the UE indicating, for a selected one of the candidate cells in the set, when the conditional SN addition or modification execution criterion is met if the configuration of the selected cell is valid. [C26] The method according to C17, wherein the configuration information is signaled to the UE in a radio resource control (RRC) message including separate execution criteria for conditional SN addition and SN change. [C27] receiving notification from the UE regarding a change of SN via a Radio Resource Control (RRC) reconfiguration complete message; Updating the candidate SN configuration to remove cells that are no longer suitable candidate cells for conditional addition or modification as SNs; The method of C17, further comprising: [C28] An apparatus for wireless communication by a user equipment (UE), comprising: Memory, at least one processor coupled to the memory; wherein the at least one processor: receiving configuration information and execution criteria from a master node (MN) identifying a set of candidate cells for a conditional addition or change of a secondary node (SN) for the UE; detecting that the performance criterion is satisfied for one of the candidate cells; taking an action to add or change the candidate cell as a SN based on the detection; An apparatus configured to: [C29] An apparatus for wireless communication by a secondary node (SN), comprising: Memory, at least one processor coupled to the memory; wherein the at least one processor: identifying a set of one or more candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; signaling information regarding said set of candidate cells to a master node (MN); An apparatus configured to: [C30] An apparatus for wireless communication by a master node (MN), comprising: Memory, at least one processor coupled to the memory; wherein the at least one processor: receiving signaling from a secondary node (SN) identifying a set of candidate cells for conditional addition or change of SN for a user equipment (UE) based on an execution criterion; signaling configuration information regarding the set of candidate cells to the UE; An apparatus configured to:

Claims

1. 1. A method for wireless communication by a user equipment (UE), comprising: receiving configuration information and execution criteria from a master node (MN) identifying a set of candidate cells for a conditional addition or modification of a secondary node (SN) for the UE, wherein the configuration information indicates first configuration information determined by the MN and second configuration information determined by the SN; monitoring performance criteria according to the first configuration information determined by the MN and performance criteria according to the second configuration information determined by the SN; detecting that the performance criterion is satisfied for one candidate cell of the set of candidate cells according to the first configuration information or the second configuration information; performing an SN change for the one candidate cell based on the detection; A method comprising:

2. The configuration information is received by the UE in a Radio Resource Control (RRC) message. The method of claim 1.

3. The RRC message contains the following information for conditional change of SN: Source cell RRC configuration change, configuring a conditional SN change execution criterion for each candidate cell in the set; or an RRC reconfiguration for each candidate cell in the set; The method of claim 2 , comprising at least one of:

4. The method of claim 1 , wherein the UE stops monitoring the performance criterion determined by an old SN after performing the SN change for the one candidate cell.

5. The method of claim 1 , further comprising: sending a notification to the MN indicating that the SN change for the one candidate cell has been performed.

6. The method of claim 5 , wherein the notification is sent via a Radio Resource Control (RRC) reconfiguration complete message.

7. An apparatus for wireless communication by a user equipment (UE), comprising: Memory, at least one processor coupled to the memory; wherein the at least one processor: receiving configuration information and execution criteria from a master node (MN) identifying a set of candidate cells for a conditional addition or modification of a secondary node (SN) for the UE, wherein the configuration information indicates first configuration information determined by the MN and second configuration information determined by the SN; monitoring performance criteria according to the first configuration information determined by the MN and performance criteria according to the second configuration information determined by the SN; detecting that the performance criterion is satisfied for one candidate cell of the set of candidate cells according to the first configuration information or the second configuration information; performing an SN change for the one candidate cell based on the detection; An apparatus configured to:

Images