Method for wireless communication at user equipment and wireless communication device

Abstract

A method of wireless communication at a user equipment (UE) and a wireless communication apparatus are provided. The wireless communication method comprises: receiving a radio resource control (RRC) configuration, the RRC configuration comprising a set of target cells for a conditional handover procedure and load information of the target cells; selecting a target cell from the set of target cells for the conditional handover procedure at least based on load information of the target cell; and performing the conditional handover procedure to transition from a source cell to the target cell.

Description

[0001] This application is a divisional application of the invention patent application with the application date of January 30, 2020, application number 202080010913.5, and invention name “Mobility Load Balancing in Wireless Communication Networks”.

[0002] Cross-references

[0003] This application claims the benefit of PCT International Application No. PCT / CN2019 / 074262, entitled “Mobility Load Balancing in Wireless Communication Network,” filed by Liu et al. on January 31, 2019, which has been assigned to the assignee of this application, and the entire contents of which are expressly incorporated herein by reference. Technical Field

[0004] Aspects of the present disclosure relate generally to wireless communications, and more particularly to techniques and apparatus for mobility load balancing in wireless communication networks. Background Art

[0005] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include 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, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE / LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

[0006] A wireless communication network may include multiple base stations (BS) that can support communication of multiple user equipments (UEs). User equipments (UEs) may communicate with base stations (BSs) via downlinks and uplinks. A downlink (or forward link) refers to a communication link from a BS to a UE, and an uplink (or reverse link) refers to a communication link from a UE to a BS. As will be described in more detail herein, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit receive point (TRP), new radio (NR) BS, 5G Node B, etc.

[0007] The above-mentioned multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user devices to communicate at municipal, national, regional and even global levels. New Radio (NR), also known as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR aims to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards by using orthogonal frequency division multiplexing (OFDMA) with cyclic prefix (CP) (CP-OFDMA) on the downlink (DL), using CP-OFDMA and / or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), and supporting beamforming, multiple input multiple output (MIMO) antenna technology and carrier aggregation. However, as the demand for mobile broadband access continues to grow, further improvements in LTE, NR and other technologies are needed. Preferably, these improvements can be applied to other multiple access technologies and telecommunication standards that adopt these technologies. Summary of the invention

[0008] Mobility load balancing may include operations and / or processes performed within a wireless communication network to balance communication loads between wireless communication devices such as base stations. For example, a load balancing process may be performed to balance loads between base stations by adjusting handover and cell reselection parameters based on the respective loads of the base stations. In NR, additional features such as mmWave beam utilization, supplementary uplink, additional radio resource control (RRC) states, central unit (CU)-distributed unit (DU) split, etc. are introduced. Therefore, an improved mobility load balancing process may be required to implement these additional features.

[0009] In some aspects, a wireless communication device may perform a load information communication process to communicate or propagate load information between wireless communication devices within a wireless communication network. In one example, load information may be communicated via an Xn interface between an NR base station and another NR base station or between an NR base station and an enhanced LTE base station. In another example, load information may be communicated via an X2 interface between an NR base station and an eNB base station. In yet another example, load information may be communicated via an F1 interface between distributed units (DUs) in an NR base station to balance loads between DUs. In yet another example, load information may be communicated between a base station and a core network via an N2 and / or S1 interface. In yet another example, load information may be communicated via an LTE Uu interface between a base station and a user equipment for conditional switching target cell selection. In other aspects, a new Xn message is proposed for negotiating switching trigger changes between base stations.

[0010] In some aspects, a wireless communication method may include sending a resource status request from a wireless communication device, the resource status request being used to request load information related to load balancing between the wireless communication device and one or more other wireless communication devices. The method may also include receiving a resource status response including the load information in response to the request.

[0011] In some aspects, a wireless communication apparatus may include means for sending a resource status request from a wireless communication device, the resource status request being used to request load information related to load balancing between the wireless communication device and one or more other wireless communication devices. The apparatus may also include means for receiving a resource status response including the load information in response to the request.

[0012] In some aspects, an apparatus for wireless communication may include a memory and one or more processors operably coupled to the memory. The memory and the one or more processors may be configured to: send a resource status request from a wireless communication device, the resource status request being used to request load information related to load balancing between the wireless communication device and one or more other wireless communication devices. The memory and the one or more processors may also be configured to: receive a resource status response including the load information in response to the request.

[0013] In some aspects, a method of wireless communication at a user equipment (UE) may include: receiving a radio resource control (RRC) configuration including a set of target cells for a conditional handover procedure and load information of the target cells. The method may also include: selecting a target cell from the set of target cells for the conditional handover procedure based at least on the load information of the target cell. The method may also include: performing a conditional handover procedure to transfer from a source cell to a target cell.

[0014] In some aspects, a wireless communication apparatus may include: a component for receiving a radio resource control (RRC) configuration at a user equipment (UE), the configuration including a set of target cells for a conditional handover procedure and load information of the target cells. The apparatus may also include: a component for selecting a target cell from the set of target cells for the conditional handover procedure based at least on the load information of the target cell at the user equipment (UE). The apparatus may also include: a component for performing a conditional handover procedure at the user equipment (UE) to transfer from a source cell to a target cell.

[0015] In some aspects, an apparatus for wireless communication may include: a memory and one or more processors operably coupled to the memory. The memory and the one or more processors may be configured to: receive a radio resource control (RRC) configuration at a user equipment (UE), the configuration including a set of target cells for a conditional handover process and load information of the target cells. The memory and the one or more processors may be configured to: select a target cell from a set of target cells for a conditional handover process at the UE based at least on the load information of the target cell. The memory and the one or more processors may be configured to: perform a conditional handover process at the UE to transfer from a source cell to a target cell.

[0016] In summary, various aspects include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, source cells, target cells, and processing systems as fully described herein with reference to and as illustrated by the accompanying drawings and description.

[0017] The features and technical advantages of the examples according to the present disclosure have been outlined quite broadly above so that the detailed description below may be better understood. Additional features and advantages will be described below. The disclosed concepts and specific examples may be easily used as a basis for modifying or designing other structures for achieving the same purposes as the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The features of the concepts disclosed herein, their organization and methods of operation, and associated advantages will be better understood from the following description when considered in conjunction with the accompanying drawings. Each of the accompanying drawings is provided for the purpose of illustration and description and not as a definition of limitations to the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to be able to understand in detail the manner in which the above features of the present disclosure are achieved, a more specific description of the above brief overview may be obtained by reference to a number of aspects, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only certain typical aspects of the present disclosure and should not be considered as limiting the scope thereof, as the description may allow for other equivalent aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0019] Figure 1 is a block diagram conceptually illustrating an example of a wireless communication network according to aspects of the present disclosure.

[0020] Figure 2 is a block diagram conceptually illustrating an example of a base station communicating with a user equipment (UE) in a wireless communication network according to aspects of the present disclosure.

[0021] Figure 3Ais a block diagram conceptually illustrating an example of a frame structure in a wireless communication network according to aspects of the present disclosure.

[0022] Figure 3B is a block diagram conceptually illustrating an example synchronous communication hierarchy in a wireless communication network in accordance with aspects of the present disclosure.

[0023] Figure 4 is a block diagram conceptually illustrating an example slot format with a normal cyclic prefix in accordance with aspects of the present disclosure.

[0024] Figure 5 An example logical architecture of a distributed radio access network (RAN) according to aspects of the present disclosure is shown.

[0025] Figure 6 An example physical architecture of a distributed RAN according to aspects of the present disclosure is shown.

[0026] Fig. 7A is a diagram illustrating an example of load information communication via an Xn interface according to aspects of the present disclosure.

[0027] Figure 7B is a diagram illustrating an example of load information communication via an X2 interface according to aspects of the present disclosure.

[0028] Figure 7C is a diagram illustrating an example of load information communication via an F1 interface according to aspects of the present disclosure.

[0029] Fig.7D is a diagram illustrating an example of load information communication through a core network via an Xn interface and / or an N2 interface according to aspects of the present disclosure.

[0030] Fig. 8A is a diagram illustrating an example of cell and beam selection for a conditional handover procedure in accordance with aspects of the present disclosure.

[0031] Figure 8B is a diagram illustrating an example of load information communication for a conditional switching process according to aspects of the present disclosure.

[0032] Fig. 9 is a diagram illustrating an example of communication of Xn messages for handover negotiation according to aspects of the present disclosure.

[0033] Fig.10 is a diagram illustrating example processing performed, for example, by a wireless communication device according to aspects of the present disclosure.

[0034] Fig.11 is a diagram illustrating example processing performed, for example, by a user device, according to aspects of the present disclosure. DETAILED DESCRIPTION

[0035] The various aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the present disclosure can be implemented in many different forms and should not be interpreted as being limited to any specific structure or function presented in the present disclosure. On the contrary, these aspects are provided to make the present disclosure comprehensive and complete, and to fully convey the scope of the present disclosure to those skilled in the art. Based at least in part on the teachings of this article, it should be understood by those skilled in the art that the scope of the present disclosure is intended to cover any aspect of the present disclosure disclosed herein, whether implemented independently of any other aspect of the present disclosure or implemented in combination with any other aspect of the present disclosure. For example, any number of aspects set forth herein can be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such a device or method, which is practiced using other structures, functions, or structures plus functions in addition to or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein can be embodied by one or more elements of the claims.

[0036] Several aspects of telecommunication systems will now be described with reference to various devices and techniques. These devices and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using hardware, software, or a combination thereof. Whether these elements are implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0037] Note that although various aspects may be described herein using terminology generally associated with 3G and / or 4G wireless technologies, various aspects of the present disclosure may be applied to other generation-based communication systems, such as 5G and higher, including NR technologies.

[0038] Figure 1 1 is a diagram showing an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and a 5G core (5GC) 190. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0039] Base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) interface with EPC 160 via backhaul link 132 (e.g., S1 interface). Base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with 5GC 190 via backhaul link 184 (e.g., N2 interface). Among other functions, base stations 102 may perform one or more of the following functions: transmission of user data, encryption and decryption of radio channels, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, positioning, and transmission of warning messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via the EPC 160 or the 5GC 190) via a backhaul link 134 (e.g., an X2, Xn, and / or N2 interface). The backhaul link 134 may be wired or wireless.

[0040] Base station 102 can communicate wirelessly with UE 104. Each base station 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network also includes a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). A communication link 120 between base station 102 and UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from base station 102 to UE 104. The communication link 120 may use multiple input multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link may be through one or more carriers. The base station 102 / UE 104 can use spectrum with a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) per carrier, which is allocated in a carrier aggregation of up to Yx MHz (x component carriers) for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The component carrier includes a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0041] Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be performed via various wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0042] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0043] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may expand the coverage of the access network and / or increase the capacity of the access network.

[0044] The base station 102, whether a small cell 102' or a large cell (e.g., a macro base station), can include an eNB, a gNodeB (gNB), or other types of base stations. Certain base stations (such as gNB 180) can operate in traditional sub-6 GHz spectrum, in millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When the gNB 180 operates at mmW or near mmW frequencies, the gNB 180 can be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of the RF in the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz and has a wavelength between 1 mm and 10 mm. Radio waves in this band can be referred to as millimeter waves. Near mmW can extend down to a frequency of 3 GHz with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also called centimeter waves. Communications using mmW / near mmW radio bands have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0045] The base station 180 may transmit beamformed signals in one or more transmit directions 182' to the UE 104. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182'. The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180 / UE 104. The transmit and receive directions of the base station 180 may be the same or may be different. The transmit and receive directions of the UE 104 may be the same or different.

[0046] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functions for MBMS user service provision and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area of ​​a broadcast specific service, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0047] 5GC 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. AMF 192 may communicate with unified data management (UDM) 196. AMF 192 is a control node that handles signaling between UE 104 and 5GC 190. Typically, AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through UPF 195. UPF 195 provides UE IP address allocation and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, intranet, IP multimedia subsystem (IMS), PS streaming services, and / or other IP services.

[0048] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), or some other suitable term. Base station 102 provides an access point to EPC 160 or 5GC 190 for UE 104. Examples of UE 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet computer, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a medical device, an implant, a sensor / actuator, a display, or any other similar functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0049] As mentioned above, Figure 1 Provided as an example only. Other examples may be found in Figure 1 Different than described.

[0050] Figure 2 A block diagram of a design 200 of a base station 102 and a UE 104 is shown, which may be Figure 1 Base station 102 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T≥1 and R≥1.

[0051] At the base station 102, the transmit processor 220 may receive data for one or more UEs from the data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on a channel quality indication (CQI) received from the UE, process (e.g., encode and modulate) the data for the UE based at least in part on the MCS selected for the UE, and provide data symbols for all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). If applicable, the transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, overhead symbols, and / or reference symbols, and can provide T output symbol streams to T modulators (MOD) 232a to 232t. Each modulator 232 can process a corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a to 232t can be transmitted through T antennas 234a to 234t, respectively. According to various aspects described in more detail below, position coding can be used to generate synchronization signals to convey additional information.

[0052] At the UE 104, antennas 252a to 252r may receive downlink signals from the base station 110 and / or other base stations, and may provide received signals to demodulators (DEMODs) 254a to 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 256 may obtain received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. The receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE 104 to the data sink 260, and provide decoded control information and system information to the controller / processor 280. The channel processor may determine a reference signal received power (RSRP), a received signal strength indication (RSSI), a reference signal received quality (RSRQ), a channel quality indication (CQI), etc. In some aspects, one or more components of UE 120 may be included in a housing.

[0053] On the uplink, at the UE 104, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). The transmit processor 264 may also generate reference symbols for use with one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266, if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 102. At the base station 102, uplink signals from the UE 104 and other UEs may be received by the antenna 234, processed by the demodulator 232, detected by the MIMO detector 236 (if applicable), and further processed by the receive processor 238 to obtain decoded data and control information transmitted by the UE 104. The receive processor 238 may provide decoded data to a data sink 239 and may provide decoded control information to a controller / processor 240. The base station 102 may include a communication unit 244 and communicate with a network controller 270 via the communication unit 244. The network controller 270 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0054] The controller / processor 240 of the base station 102, the controller / processor 280 of the UE 104, and / or Figure 2 Any other components of the controller / processor 240 of the base station 102, the controller / processor 280 of the UE 104, and / or Figure 2 Any other component of the can perform or direct e.g. Fig.10 Processing 1000 operations, Fig.11 Process 1100, and / or other processes as described herein. Memories 242 and 282 may store data and program codes for base station 102 and UE 104, respectively. Scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0055] In some aspects, the base station 102 may include: means for receiving a resource status request requesting load information associated with load balancing between the wireless communication device and one or more other wireless communication devices; and means for sending a resource status response including the load information in response to the request. In some aspects, such means may include in conjunction with Figure 2 One or more components of base station 102 are described.

[0056] In some aspects, the UE 104 may include: a component for receiving a radio resource control (RRC) configuration, the RRC configuration including a set of target cells for a conditional handover procedure and load information of the target cells; a component for selecting a target cell from the set of target cells for the conditional handover procedure based at least on the load information of the target cells; and a component for performing a conditional handover procedure at a user equipment (UE) to transfer from a source cell to a target cell. In some aspects, such components may include combining Figure 2 One or more components of UE 104 are described.

[0057] As mentioned above, Figure 2 Provided as examples only. Other examples may be relevant to Figure 2 Different than described.

[0058] Figure 3A An example frame structure 300 for frequency division duplex (FDD) in a telecommunication system (e.g., NR) is shown. The transmission timeline for each of the downlink and uplink may be divided into radio frame units (sometimes referred to as frames). Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be divided into a set of Z (Z ≥ 1) subframes (e.g., with indices from 0 to Z-1). Each subframe may have a predetermined duration (e.g., 1 ms) and may include a set of time slots (e.g., Figure 3A , where m is a number used for transmission, such as 0, 1, 2, 3, 4, etc.). Each time slot may include a set of L symbol periods. For example, each time slot may include fourteen symbol periods (e.g., Figure 3A In some aspects, the scheduling unit of FDD can be frame-based, subframe-based, slot-based, symbol-based, etc.

[0059] Although some techniques are described herein in conjunction with frames, subframes, time slots, etc., these techniques may be equally applicable to other types of wireless communication structures, which may be referred to in 5G NR using terms other than "frames," "subframes," "time slots," etc. In some aspects, a wireless communication structure may refer to a periodic, time-constrained communication unit defined by a wireless communication standard and / or protocol. Additionally or alternatively, a wireless communication structure may be used in conjunction with Figure 3A The wireless communication structures are configured differently than those shown in FIG.

[0060] In some telecommunications (e.g., NR), a base station may send synchronization signals. For example, a base station may send a primary synchronization signal (PSS), a secondary synchronization signal (SSS), etc. on the downlink for each cell supported by the base station. The PSS and SSS may be used by the UE for cell search and acquisition. For example, the UE may use the PSS to determine symbol timing, and the UE may use the SSS to determine the physical cell identifier and frame timing associated with the base station. The base station may also send a physical broadcast channel (PBCH). The PBCH may carry some system information, such as system information that supports initial access of the UE.

[0061] In some aspects, the base station may send the PSS, SSS, and / or PBCH according to a synchronization communication level (e.g., a synchronization signal (SS) level) including multiple synchronization communications (e.g., SS blocks), as described below in conjunction with Figure 3B described.

[0062] Figure 3B is a block diagram conceptually illustrating an example SS hierarchy structure, which is an example of a synchronous communication hierarchy structure. Figure 3B As shown, the SS hierarchy may include an SS burst set, which may include multiple SS bursts (identified as SS burst 0 to SS burst B-1, where B is the maximum number of repetitions of the SS burst that can be sent by the base station). As further shown, each SS burst may include one or more SS blocks (identified as SS block 0 to SS block (bmax_SS-1), where bmax_SS-1 is the maximum number of SS blocks that can be carried by the SS burst). In some aspects, different SS blocks may be beamformed in different ways. The SS burst set may be sent by the wireless node periodically, for example, once every X milliseconds, such as Figure 3B In some aspects, the SS burst set may have a fixed or dynamic length. Figure 3B is shown as Y milliseconds.

[0063] Figure 3B The SS burst sets shown in are examples of synchronous communication sets, and other synchronous communication sets may be used in conjunction with the techniques described herein. Figure 3B The SS blocks shown in are examples of synchronous communications, and other synchronous communications may be used in conjunction with the techniques described herein.

[0064] In some aspects, an SS block includes resources that carry PSS, SSS, PBCH, and / or other synchronization signals (e.g., a third synchronization signal (TSS)) and / or synchronization channels. In some aspects, multiple SS blocks are included in an SS burst, and the PSS, SSS, and / or PBCH of each SS block across the SS burst may be the same. In some aspects, a single SS block may be included in an SS burst. In some aspects, the length of an SS block may be at least four symbol periods, where each symbol carries one or more of a PSS (e.g., occupying one symbol), a SSS (e.g., occupying one symbol), and / or a PBCH (e.g., occupying two symbols).

[0065] In some aspects, the symbols of the SS blocks are consecutive, such as Figure 3B As shown. In some aspects, the symbols of the SS blocks are discontinuous. Similarly, in some aspects, one or more SS blocks of an SS burst may be sent in continuous radio resources (e.g., continuous symbol periods) during one or more time slots. Additionally or alternatively, one or more SS blocks of an SS burst may be sent in discontinuous radio resources.

[0066] In some aspects, an SS burst may have a burst period, whereby a base station may send an SS block of an SS burst according to the burst period. In other words, an SS block may repeat during each SS burst. In some aspects, an SS burst set may have a burst set period, whereby a base station may send an SS burst of an SS burst set according to a fixed burst set period. In other words, an SS burst may repeat during each SS burst set.

[0067] The base station may send system information, such as system information blocks (SIBs), on a physical downlink shared channel (PDSCH) in certain time slots. The base station may send control information / data on a physical downlink control channel (PDCCH) in C symbol periods of a time slot, where B may be configurable for each time slot. The base station may send traffic data and / or other data on the PDSCH in the remaining symbol periods of each time slot.

[0068] As mentioned above, Figure 3A and 3B are provided as examples. Other examples may differ from those described in Figure 3A and 3B Examples described.

[0069] Figure 4An example slot format 410 with a normal cyclic prefix is ​​shown. The available time-frequency resources may be partitioned into resource blocks. Each resource block may cover a set of subcarriers (e.g., 12 subcarriers) in a slot and may include multiple resource elements. Each resource element may cover one subcarrier in a symbol period (e.g., in units of time) and may be used to send one modulation symbol, which may be real or complex valued.

[0070] In some telecommunication systems (e.g., NR), an interlaced structure may be used for each of the downlink and uplink of FDD. For example, Q interlaces indexed from 0 to Q-1 may be defined, where Q may be equal to 4, 6, 8, 10, or some other value. Each interlace may include time slots spaced apart by Q frames. Specifically, interlace q may include time slots q, q+Q, q+2Q, etc., where q∈{0, ..., Q-1}.

[0071] A UE may be located within the coverage of multiple BSs. One of these BSs may be selected to serve the UE. The serving BS may be selected based at least in part on various criteria such as received signal strength, received signal quality, path loss, etc. The received signal quality may be quantified by a signal-to-noise ratio (SINR) or a reference signal received quality (RSRQ) or some other metric. The UE may operate in a dominant interference scenario, where the UE may observe high interference from one or more interfering BSs.

[0072] Although aspects of the examples described herein may be associated with NR or 5G technology, aspects of the present disclosure may be applicable to other wireless communication systems. New Radio (NR) may refer to a system configured to operate in accordance with a new air interface (e.g., in addition to an air interface based on Orthogonal Frequency Division Multiple Access (OFDMA)) or a fixed transport layer (e.g., in addition to the Internet Protocol (IP)). In some aspects, NR may use OFDM with CP (referred to herein as cyclic prefix OFDM or CP-OFDM) and / or SC-FDM on the uplink, may use CP-OFDM on the downlink and include support for half-duplex operation using time division duplex (TDD). In some aspects, NR may, for example, utilize OFDM with CP (referred to herein as CP-OFDM) and / or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using TDD. NR may include enhanced mobile broadband (eMBB) services for wide bandwidths (e.g., 80 megahertz (MHz) and above), millimeter wave (mmW) for high carrier frequencies (e.g., 60 gigahertz (GHz)), massive MTC (mMTC) for non-backward compatible MTC technologies, and / or mission critical ultra-reliable low latency communication (URLLC) services.

[0073] In some aspects, a single component carrier bandwidth of 100 MHZ may be supported. NR resource blocks may span 12 subcarriers with a subcarrier bandwidth of 60 or 120 kilohertz (kHz) in a 0.1 millisecond (ms) duration. Each radio frame may include 40 slots and may have a length of 10 ms. Thus, each slot may have a length of 0.25 ms. Each slot may indicate a link direction (e.g., DL or UL) for data transmission, and the link direction for each slot may be switched dynamically. Each slot may include DL / UL data and DL / UL control data.

[0074] Beamforming may be supported and the beam direction may be dynamically configured. MIMO transmission with precoding may also be supported. MIMO configuration in DL may support up to 8 transmit antennas with multi-layer DL transmission of up to 8 streams and up to 2 streams per UE. Multi-layer transmission with up to 2 streams per UE may be supported. Aggregation of multiple cells with up to 8 serving cells may be supported. Alternatively, NR may support different air interfaces other than the interface that handles OFDM. NR networks may include entities such as a central unit or distributed units.

[0075] As mentioned above, Figure 4 are provided as examples. Other examples may be relevant to Figure 4 Different than described.

[0076] Figure 5 An example logical architecture of a distributed RAN 500 according to various aspects of the present disclosure is shown. A 5G access node 506 may include an access node controller (ANC) 502. The ANC may be a central unit (CU) of the distributed RAN 500. The ANC may communicate with one or more TRPs via an F1 interface. The backhaul interface to the next generation core network (NG-CN) 504 may terminate at the ANC. The backhaul interface to an adjacent next generation access node (NG-AN) may terminate at the ANC. The AN may include one or more TRPs 508 (which may also be referred to as BS, NR BS, Node B, 5G NB, AP, gNB, or some other terminology). As described above, TRP may be used interchangeably with "cell".

[0077] The TRP 508 may be a distributed unit (DU). The TRP may be connected to one ANC (ANC 502) or more than one ANC (not shown) via an F1 interface. For example, for RAN sharing, Radio as a Service (RaaS), and service-specific AND deployments, the TRP may be connected to multiple ANCs. The TRP may include one or more antenna ports. The TRP may be configured to provide services to the UE individually (e.g., dynamically selected) or jointly (e.g., joint transmission).

[0078] The local architecture of RAN 500 can be used to illustrate the fronthaul definition. The architecture can be defined to support fronthaul solutions across different deployment types. For example, the architecture can be based at least in part on the sending network capabilities (e.g., bandwidth, delay and / or jitter).

[0079] The architecture may share features and / or components with LTE. According to various aspects, the next generation AN (NG-AN) 510 may support dual connectivity with NR. The NG-AN may share a common fronthaul for LTE and NR.

[0080] The architecture may enable coordination between and among TRPs 508. For example, coordination may be provisioned within and / or across TRPs via ANC 502. According to various aspects, an inter-TRP interface may not be required / present.

[0081] According to various aspects, there may be a dynamic configuration of split logical functions within the architecture of the RAN 500. Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Medium Access Control (MAC) protocols may be adaptively placed at the ANC or TRP.

[0082] According to various aspects, a BS may include a central unit (CU) (eg, ANC 502) and / or one or more distributed units (eg, one or more TRPs 508).

[0083] As mentioned above, Figure 5 Provided as an example only. Other examples may vary from Figure 5 Examples described.

[0084] Figure 6 An example physical architecture of a distributed RAN 600 according to aspects of the present disclosure is shown. A centralized core network unit (C-CU) 602 may host core network functions. The C-CU may be centrally deployed. C-CU functions may be offloaded (e.g., to Advanced Wireless Services (AWS)) to focus on handling peak capacity.

[0085] A centralized RAN unit (C-RU) 604 may host one or more ANC functions. Optionally, the C-RU may host core network functions locally. The C-RU may have a distributed deployment. The C-RU may be closer to the network edge.

[0086] A distributed unit (DU) 606 may host one or more TRPs. The DU may be located at the edge of the network with radio frequency (RF) capabilities.

[0087] As mentioned above, Figure 6 Provided as an example only. Other examples may vary from Figure 6 Examples described.

[0088] In some communication systems (e.g., 5G or NR), a mobility load balancing process may be performed to balance the loads borne by different base stations. For example, based on the load information of different base stations, the base station may perform one or more of a handover process, a cell reselection process, a secondary node addition / modification process, a bearer offloading process, etc., to balance the load between base stations. This can prevent one base station from being overloaded and can improve the overall operating efficiency of the wireless network.

[0089] To this end, the base station may monitor and collect load information, and may communicate the load information to other base stations. The load information may include radio resource usage information indicating the utilization rate and / or usage amount of different radio resources. For example, the radio resource usage information may include information related to guaranteed bit rate (GBR) physical resource block (PRB) utilization and non-GBR PRB utilization. In another example, the radio resource usage information may include beam utilization information indicating the utilization of different beams and corresponding directions. When a random access procedure (RACH) is performed during a handover process, the beam utilization information may provide a reference to a beam access priority regarding a beam load.

[0090] The load information may include radio resource usage information per service type. For example, the load information may include usage information about different types of services (e.g., enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), enhanced machine type communication (eMTC), etc.). The radio resource usage information per service type may indicate an absolute value indicating an actual ratio and / or amount of resource usage for the service type. In another example, the radio resource usage information per service type may indicate a relative value indicating a percentage of usage of a particular service type relative to other service types.

[0091] Different service types may have different requirements for radio resources. For example, eMBB may require more resources to handle large bandwidth transmissions compared to URLLC. Nodes may reserve different amounts of resources based on different service types. Therefore, one particular service type may reach a high load state, while another service type may still have room to accept incoming accesses.

[0092] The load information may include per-carrier load information. The per-carrier load information may indicate the loads of different carriers. For example, for NR, in addition to the dedicated uplink carrier, the supplementary uplink (SUL) may use a low-frequency carrier for uplink transmission. The per-carrier load information may indicate the load information at the SUL carrier and the load information at the dedicated carrier. The SUL may generally be located in a different frequency range than the dedicated UL and may have different radio conditions. Therefore, for the same loading level, the SUL and the dedicated UL may have different loading spaces.

[0093] The load information may also include hardware load information. For example, the hardware load information may include central unit (CU) hardware load information indicating the load at the CU. The hardware load information may also include per distributed unit (DU) hardware load information indicating the load at each DU. The CU and DU utilize resources of different protocol layers. For example, the CU utilizes the packet data convergence protocol (PDCP) and the radio link control (RLC) layer, while the DU utilizes resources in the MAC and PHY layers. Therefore, the CU and DU hardware load information may include usage information related to different layers of resources.

[0094] The load information may include transport network layer (TNL) load information, which indicates the load borne at different TNLs. For example, in NR, the TNL load information may include load information of N2 and / or N3 TNL load, F1 TNL load, etc. The CU utilizes F1, X2, Xn, N2, N3 TNLs, while the DU utilizes F1 TNL. Therefore, the CU and DU hardware load information may include load information related to different TNLs.

[0095] The load information may also include composite available capacity (CAC) information. The load information may also include the number of UEs in connected mode and / or the number of UEs in RRC_INACTIVE state. These numbers may be used for access control. For example, when the base station reaches a threshold number of UEs in connected mode and / or a threshold number of UEs in RRC_INACTIVE state, access may be restricted. This may prevent the base station from being overloaded by too many UEs.

[0096] In NR, load information can be configured based on CU-DU split characteristics. For example, CU load information can include CU hardware load, F1, X2, Xn, N2, N3 TNL load, composite available capacity, the number of UEs in connected mode, and the number of UEs in RRC_INACTIVE state. DU load information can include DU hardware load, radio resource usage information (e.g., GBR PRB / non-GBR PRB utilization and beam utilization), per-service type radio resource usage information, per-carrier load information (e.g., SUL load), F1 TNL load, and composite available capacity.

[0097] Various load information can be communicated and shared between different entities in the wireless network through different communication interfaces. In LTE, load information can be communicated between cells of interest via X2 and / or S1 communication procedures to balance the load between base stations by adjusting handover and / or cell reselection parameters based on the load information.

[0098] In NR, load information can be communicated via the Xn interface between NR base stations and / or between NR and enhanced LTE (eLTE) stations. The load information communicated via the Xn interface can be used to implement a switching process, a cell reselection process, a secondary node (SN) addition and / or modification process, and / or a bearer unloading process from the SN. In some aspects, the load information can be communicated via the X2 interface between the NR base station and the LTE base station. The load information communicated via the X2 interface can be used to implement the E-UTRA-NR dual connection (EN-DC) SN addition and / or modification process and the bearer unloading process from the master node (MN) to the SN.

[0099] In some aspects, the load information can be communicated via the F1 interface between the CU and the DU for load balancing between the DUs. In some aspects, the load information can be communicated via the N2 interface between the base station and the core network. The load information communicated via the N2 interface can be used to implement the switching process and / or the cell reselection process. In some aspects, the load information can be communicated via the Uu interface between the base station and the UE. The load information communicated via the Uu interface can be used to implement conditional switching target cell selection.

[0100] Fig. 7A 7 is a diagram illustrating an example 710 of load information communication via an Xn interface according to various aspects of the present disclosure. Fig. 7A As shown, base station 712 and base station 714 can communicate via an Xn interface. Base stations 712 and 714 can be as follows Figure 1 and 2 . Each of base stations 712 and 714 may be an NR base station or an eLTE base station. Base station 712 may send a resource status request 716 to base station 714 via an Xn interface. Resource status request 716 may include a request for measurement of load information. The requested load information may include radio resource usage information (e.g., GBR PRB / non-GBR PRB utilization information and / or beam utilization information), per-service type radio resource usage information, per-carrier load information (including SUL load), hardware load information (including CU and per-DU hardware load), TNL load information (including N2, N3 and / or F1 TNL load), composite available capacity, the number of UEs in connected mode, and / or the number of UEs in RRC_INACTIVE state.

[0101] The base station 714 may receive a resource status request 716, and may monitor the communication status and determine the load information based on the resource status request. For example, the base station 714 may determine the current load conditions at different radio resources, different beams, different service types, different carriers, CUs and each DU, different TNLs, etc. The base station 714 may then generate a resource status response 718 including the requested load information, and may send the resource status response 718 back to the base station 712. The base station 712 may use the load information to perform various load balancing processes. For example, the base station 712 may adjust parameters for a handover process, a cell reselection process, an SN add / modify process, and / or a bearer unloading process based on the load information received from the base station 714. Therefore, load balancing may be achieved between the base stations 712 and 714. This may prevent one base station from being overloaded, and may improve the overall operational efficiency of the wireless network.

[0102] Figure 7B 7 is a diagram illustrating an example 720 of load information communication via an X2 interface according to various aspects of the present disclosure. Figure 7B As shown, base station 722 and base station 724 can communicate via an X2 interface. Base stations 722 and 724 can be as follows Figure 1 and 2An example of a base station 102 described in . One of the base stations 722 and 724 may be an eNB base station, and the other of the base stations 722 and 724 may be an NR base station (e.g., a non-standalone type). The base station 722 may send a resource status request 726 to the base station 724 via an X2 interface. The resource status request 726 may include a request for measurement of load information. The requested load information may include radio resource usage information (e.g., GBR PRB / non-GBR PRB utilization information and / or beam utilization information), per-service type radio resource usage information, per-carrier load information (including SUL load), hardware load information (including CU and per-DU hardware load), TNL load information (including N2, N3 and / or F1 TNL load), composite available capacity, the number of UEs in connected mode, and / or the number of UEs in RRC_INACTIVE state.

[0103] The base station 724 may receive a resource status request 726, and may monitor and determine load information based on the resource status request. For example, the base station 724 may determine the current load conditions at different radio resources, different beams, different service types, different carriers, CUs and each DU, different TNLs, etc. The base station 724 may then generate a resource status response 728 including the requested load information, and may send the resource status response 728 back to the base station 722. The base station 722 may use the load information to perform various load balancing processes. For example, the base station 722 may adjust the parameters of the SN add / modify process and / or the bearer unloading process based on the load information received from the base station 724. Therefore, load balancing may be achieved between the primary node and the secondary node (e.g., base stations 722 and 724). This may prevent the primary node or the secondary node from being overloaded, and may improve the overall operational efficiency of the wireless network.

[0104] Figure 7C 7 is a diagram illustrating an example 730 of load information communication via an F1 interface according to various aspects of the present disclosure. Figure 7C As shown, the central unit (CU) 732 and the distributed unit (DU) 734 can communicate via the F1 interface. The CU 732 and the DU 734 can be as follows Figure 5 and Figure 6732 may send a resource status request 736 to one or more DUs 734 via an F1 interface. The resource status request 736 may include a request for measurement of load information. The requested load information may include DU load information (e.g., DU hardware load), radio resource usage information (e.g., GBR PRB / non-GBR PRB utilization information and / or beam utilization information), per-service type radio resource usage information, per-carrier load information (including SUL load), F1 TNL load, composite available capacity, etc.

[0105] DU 734 can receive resource status request 736, and can monitor and determine load information based on resource status request 736. For example, DU 734 can determine the current load status at hardware level, F1 interface, different radio resources, different beams, different service types, different carriers, etc. One or more DU 734 can then generate a resource status response 738 including the requested load information, and can send the resource status response 738 back to CU 732 via the F1 interface. CU 732 can use the DU load information to perform various load balancing processes between DU 734. For example, CU 732 can allocate additional UEs to corresponding DU 734 based on the load information of DU 734. More UEs can be allocated to DUs with smaller loads, while fewer UEs can be allocated to DUs with larger loads. This can prevent DU 734 from being overloaded, and can improve the overall operating efficiency of the wireless network.

[0106] In some aspects, DU 734 can communicate with the user via interface F l Request and receive CU load information from CU 732. CU load information may include CU hardware load, F1, X2, Xn, N2, N3 TNL load, composite available capacity, number of UEs in connected mode, and number of UEs in RRC_INACTIVE state. For load balancing purposes, DU 732 may be informed of the load condition at CU 732.

[0107] Fig.7D 7 is a diagram illustrating an example 740 of load information communication through a core network via an Xn interface and / or an N2 interface according to various aspects of the present disclosure. Fig.7D As shown, the eNB base station 742 can communicate with the evolved packet core (EPC) 744 via an S1 interface. The NG-RAN base station 748 can communicate with the access and mobility management function (AMF) 746 via an N2 interface. The eNB base station 742 and the NG-RAN base station 748 can communicate load information via the core network.

[0108] The eNB base station 742 may initiate a request for measurement by sending a resource status request to the EPC 744 via the S1 interface in the form of an MME direct information transmission 752. The EPC 744 may forward the resource status request to the AMF 746 in the form of a direct information transmission 754. The AMF 746 may send the resource status request to the NG-RAN base station 748 via the N2 interface in the form of an NG-RAN direct information transmission 756. The resource status request may include a request for measurement of load information. The requested load information may include radio resource usage information (e.g., GBR PRB / non-GBR PRB utilization information and / or beam utilization information), per-service type radio resource usage information, per-carrier load information (including SUL load), hardware load information (including CU and per-DU hardware load), TNL load information (including N2, N3 and / or F1 TNL load), composite available capacity, the number of UEs in connected mode, and / or the number of UEs in RRC_INACTIVE state.

[0109] The NG-RAN base station 748 may receive the resource status request and may monitor and determine load information based on the resource status request. For example, the NG-RAN base station 748 may determine the current load conditions at different radio resources, different beams, different service types, different carriers, CUs and per DUs, different TNLs, etc. The NG-RAN base station 748 may then generate a resource status response including the requested load information and may send the resource status response back to the AMF 746 in the form of an AMF direct information transmission 762. The AMF 746 may send the resource status response to the EPC 744 in the form of a direct information transmission. The EPC 744 may send the resource status response back to the eNB base station 742 in the form of an eNB direct information transmission 766.

[0110] The eNB base station 742 can use the load information to perform various load balancing processes. For example, the base station 742 can adjust parameters for a handover process and / or a cell reselection process based on the load information received from the NG-RAN base station 748. Thus, load balancing can be achieved between the eNB base station and the NG-RAN base station (e.g., base stations 742 and 748). This can prevent load imbalance between the eNB base station and the NG-RAN base station, and can improve the overall operating efficiency of the wireless network.

[0111] In some aspects, the NG-RAN 748 may initiate a resource status request to request load information from the eNB base station 742 via the core network. In this case, the communication process may be similar but reversed, as the resource status request may originate from the NG-RAN 748, reach the eNB base station 742 via the core network, and the eNB base station 742 may send a resource status response including the load information of the eNB base station 742 back to the NG-RAN 748 via the core network.

[0112] Relative to other technologies, the conditional handover process can be used to improve mobile robustness. For example, by implementing the conditional handover process, the network can reduce the possibility of radio link failure between the UE and the BS when the link quality between the UE and the BS drops too fast to apply the forward handover process. In the conditional handover process, the BS can actively provide the UE with a conditional handover configuration. For example, the BS can provide a conditional handover configuration before a handover triggering event. In this case, the conditional handover configuration may include the configuration of a candidate target cell, an indication of the conditions for triggering the conditional handover process, etc. When the conditions for triggering the conditional handover process are met, the UE may initiate a random access channel process to transfer to the target cell. In this way, the handover delay is reduced relative to the forward handover process, wherein the UE may send a measurement report and / or receive a radio resource control (RRC) configuration message before performing the forward handover process.

[0113] Fig. 8A 8 is a diagram illustrating an example 800 of cell and beam selection for a conditional handover procedure in accordance with various aspects of the present disclosure. Fig. 8A As shown, example 800 may include a UE 852 and a set of BSs 854, 856, and 858. For example, BS 854 may be a source cell, BS 856 may be a first target cell, and BS 858 may become a second target cell.

[0114] As in Fig. 8A802 and 804, UE 852 may receive a measurement control message from a source cell and may provide a measurement report to the source cell. For example, the source cell may provide a signal to UE 852 to enable UE 852 to measure the signal strength of the signal and report the signal strength of the signal. In some aspects, the measurement control message may include information identifying the configuration for UE 852. For example, the source cell may indicate which parameter UE 852 is to determine, such as a signal strength parameter (e.g., reference signal received power (RSRP)), a signal quality parameter (e.g., reference signal received quality (RSRQ)), etc. In this case, UE 852 may report that the parameter does not meet a threshold, which may trigger the source cell to determine the availability of the target cell for handover. In some aspects, the source cell may provide information identifying a threshold. In some aspects, UE 852 may obtain stored information identifying a threshold.

[0115] As in Fig. 8A 806, the source cell may make a handover decision based at least in part on the measurement report. For example, the source cell may determine that the conditions for performing conditional handover are met based at least in part on the measurement report. In this case, the source cell may determine that the UE 852 is to be handed over from the source cell to the target cell. In some aspects, the source cell may determine that the conditions for performing conditional handover are met based at least in part on the signal quality of the link between the UE 852 and the source cell not meeting a threshold. Additionally or alternatively, the source cell may determine that the conditions for performing conditional handover are met based at least in part on the beam quality of the beam used by the UE 852 and / or the source cell not meeting a threshold.

[0116] As in Fig. 8A As further shown in the figure and via reference numerals 808, 810, 812, and 814, the source cell may provide a handover request to the first target cell and / or the second target cell, and may receive a handover request confirmation. For example, the source cell may provide a handover request to the first target cell and the second target cell, the first target cell and the second target cell may be candidate target cells, and the first target cell and the second target cell may perform an admission control process. In this case, the first target cell and the second target cell may determine whether the UE 852 can be connected to the first target cell and the second target cell, respectively (e.g., based at least in part on cell congestion, cell status, etc.). Based at least in part on performing admission control, the first target cell and the second target cell may provide a confirmation to the source cell to indicate that the UE 852 can be transferred to the first target cell and / or the second target cell.

[0117] As in Fig. 8A8 and further shown via reference numeral 716, the source cell may provide a radio resource control (RRC) reconfiguration message with a conditional handover configuration and a resource reservation configuration to the UE 852. For example, the source cell may provide an RRC reconfiguration message to identify a configuration for conditional handover, change a configuration for conditional handover, etc. In some aspects, the source cell may provide an RRC reconfiguration message to identify a set of candidate target cells (e.g., a first target cell, a second target cell, etc.), conditional handover conditions (e.g., for selecting a target cell and determining a threshold cell quality for transfer to the target cell), etc. In some aspects, the source cell may identify an offset value. For example, the source cell may identify an event-triggered configuration offset value indicating an offset to be applied to a threshold corresponding to a measurement event that triggers a measurement report. In some aspects, the source cell may identify a priority of a candidate target cell. For example, the source cell may identify multiple priorities of multiple candidate target cells so that the UE 852 can determine which candidate target cell among the multiple candidate target cells to transfer to when performing a conditional handover.

[0118] In some aspects, the source cell may provide an RRC reconfiguration message to convey a measurement identifier. The measurement identifier may identify a measurement configuration that links a measurement object and a reporting configuration. In this case, the UE 852 may use the measurement identifier to determine which object (e.g., which parameter) to measure, and which threshold triggers the report of the measurement of the object. In this way, the source cell may update the conditions associated with performing a conditional handover. For example, the source cell may include an information element that identifies a threshold criterion for handing over from the source cell to a candidate target cell, and the UE 852 may use the threshold criterion to select a candidate target cell and a beam. In some aspects, the UE 852 may determine a candidate cell threshold offset, a handover priority identifier, etc. based at least in part on the information element.

[0119] In some aspects, the source cell may indicate to the UE 852 that the conditional handover will be triggered based at least in part on the quality of the beam identified in the random access channel configuration. For example, the source cell may include information identifying a candidate target cell identifier, a beam threshold offset, a handover priority indicator, and the like. Additionally or alternatively, the source cell may indicate that the conditional handover will be triggered based at least in part on the quality of the beam identified in the conditional handover condition identifier. In this case, the source cell may include information identifying a candidate cell identifier, a beam list (e.g., a channel state information reference signal (CSI-RS), a synchronization signal block (SSB), etc.), a beam threshold, a handover priority indicator, and the like.

[0120] As in Fig. 8A8 and further shown by reference numeral 818, the UE 852 may select a target cell and a beam from a plurality of candidate target cells for a conditional handover procedure. For example, the UE 852 may evaluate the plurality of candidate target cells to determine whether at least one candidate target cell satisfies a condition for performing a conditional handover to the at least one candidate target cell. In this case, the condition may be related to a candidate target cell having a cell quality metric that satisfies a threshold, a beam quality metric that satisfies a threshold, etc., as described herein. Based at least in part on evaluating the plurality of candidate target cells, the UE 852 may select a beam associated with a first target cell, a beam associated with a second target cell, etc.

[0121] In some aspects, UE 852 may perform cell selection and then may subsequently perform beam selection. For example, UE 852 may select a target cell from a plurality of candidate target cells configured at least in part based on an RRC reconfiguration message from a source cell. In this case, UE 852 may then select a beam from a group of one or more beams of the selected target cell to perform a random access channel process to transfer to the selected target cell. For example, UE 852 may select a beam based at least in part on a beam list of one or more beams of the selected target cell received from the source cell. In some aspects, UE 852 may select a beam based at least in part on a threshold. For example, UE 852 may determine that a particular beam meets a threshold beam quality and may select the particular beam. In contrast, if no beam meets the threshold beam quality, UE 852 may fall back to a contention-based random access (CBRA) process and may select any beam of the selected target cell based at least in part on falling back to the CBRA process. In some aspects, UE 852 may perform cell selection and beam selection simultaneously for conditional handover. For example, UE 852 may process information related to both the target cell and the beam associated therewith to perform cell selection and beam selection.

[0122] In some aspects, the UE 852 may determine cell quality and may select a target cell and / or beam based at least in part on the cell quality. For example, when the candidate target cells are each associated with a single beam, the UE 852 may determine that a single candidate target cell is associated with a cell quality that satisfies a threshold, and may select a single candidate target cell as the target cell. Additionally or alternatively, when the UE 852 determines that multiple candidate target cells are associated with a cell quality that satisfies a threshold, the UE 852 may select a specific candidate target cell associated with the best cell quality relative to other candidate target cells. Additionally or alternatively, the UE 852 may select a target cell based at least in part on an index value. For example, the UE 852 may select a first candidate target cell having a cell quality that satisfies a threshold. In this case, the first candidate target cell may be first in terms of cell index, frequency index, identification order in a cell list, etc. Additionally or alternatively, the UE 852 may select a target cell based at least in part on a priority. For example, the UE 852 may select a candidate target cell having a cell quality satisfying a threshold that is associated with a highest priority relative to other candidate target cells having cell qualities satisfying the threshold.

[0123] In some aspects, the UE 852 may select a target cell based at least in part on a comparison of multiple beams of different candidate target cells. For example, when the UE 852 is configured with multiple beams for each candidate target cell, the UE 852 may compare the best beam relative to the beam quality metric to select the candidate target cell as the target cell. In this case, the UE 852 may select the candidate target cell based at least in part on the best beam of the candidate target cell (e.g., the beam with the highest beam quality metric of the beam of the candidate target cell), which has a higher beam quality metric than other best beams of other candidate target cells. Additionally or alternatively, the UE 852 may select a first candidate target cell that has a best beam that satisfies a beam quality threshold relative to the beam quality metric. Additionally or alternatively, the UE 852 may select a candidate target cell with the highest priority among the candidate target cells whose best beams satisfy the threshold of the beam quality metric relative to the beam quality metric.

[0124] In some aspects, the UE 852 may select one of the multiple beams of the multiple candidate target cells. For example, when the UE 852 is configured with multiple beams for each candidate target cell, the UE 852 may perform beam selection for all beams of all candidate target cells. In this case, the UE 852 may select the beam with the highest beam quality metric, the first beam in order (e.g., with respect to an index value) that satisfies a beam quality threshold, the beam associated with the highest priority of the associated cell, etc.

[0125] In some aspects, the UE 852 may select a beam based at least in part on an averaging process. For example, the UE 852 may determine the beam set quality of each candidate target cell based at least in part on multiple beam qualities of multiple beams of the respective candidate target cells, and may select the candidate target cell based at least in part on the corresponding beam set quality. In some aspects, the UE 852 may select the candidate target cell with the highest beam set quality relative to other candidate target cells. Additionally or alternatively, the UE 852 may select the first candidate target cell (with respect to the index value) in order with a beam set quality that satisfies a threshold. Additionally or alternatively, the UE 852 may select a candidate target cell with a beam set quality that satisfies a threshold, which candidate target cell has the highest priority relative to other candidate target cells. In some aspects, the UE 852 may report an event that triggers a handover to the source cell. For example, when cell quality triggers a handover, the UE 852 may report one or more measurements associated with cell quality.

[0126] In some aspects, the UE 852 may perform cell selection and / or beam selection based on load information associated with the respective target cells and the respective beams. For example, the load information may be incorporated into the parameters used to select a cell and / or select a beam, such that a cell or beam with more load may have a lower likelihood of being selected. This may prevent a cell or beam with a relatively high load from being overloaded and allow a cell or beam with a relatively low load to be selected and utilized.

[0127] As in Fig. 8A 8 and further illustrated by reference numeral 820, based at least in part on selecting, for example, a first target cell as a target cell for a conditional handover procedure, the UE 852 may communicate with the first target cell to transfer to the first target cell. For example, the UE 852 may exchange a set of messages with the first target cell according to an access procedure to connect to the first target cell. In some aspects, the access procedure may be a contention-free access procedure, an access procedure without a random access channel (RACH), a contention-based RACH procedure, etc. In this way, the UE 852 determines whether the UE 852 is able to access the first target cell in a conditional handover scenario to switch to the first target cell.

[0128] As in Fig. 8A As further shown in the figure and via reference numerals 822 and 824, UE 852 may provide an indication of the completion of the handover command to the first target cell, and may trigger a response message based at least in part on performing a conditional handover procedure. For example, based at least in part on performing an access procedure, UE 852 may indicate that UE 852 is connecting to the first target cell and does not abandon the connection to the first target cell to remain on the source cell. In this case, the first target cell may provide a confirmation message to the source cell confirming that UE 852 is connecting to the first target cell (shown as "CHO ​​ACK"). In this way, the first target cell enables the source cell to begin transmitting information to the first target cell, which may enable the first target cell to become a serving cell for UE 852.

[0129] As in Fig. 8A 8 and further illustrated by reference numerals 826 and 828, in some aspects, the source cell may provide a conditional handover cancel message to the second target cell, and a response message may be received. For example, the source cell may provide a conditional handover cancel message to indicate that UE 852 is not being transferred to the second target cell (e.g., based at least in part on receiving a confirmation message confirming that UE 852 is successfully connected to the first target cell). In this case, the source cell causes the admission control process of the second target cell to end.

[0130] As in Fig. 8A 830 and 832, the source cell may provide a sequence number status transfer message to the first target cell, and data forwarding to the first target cell may be performed. For example, based at least in part on receiving a confirmation message confirming that UE 852 is connecting to the first target cell, the source cell may provide a sequence number status, and data for UE 852 may be forwarded to the first target cell to enable handover to the first target cell and avoid data loss from transmission to UE 852.

[0131] As in Fig. 8A As further shown in FIG. 8 and via reference numeral 834, the first target cell may provide a confirmation message indicating that the conditional handover procedure is complete. For example, the first target cell may indicate to the source cell that the conditional handover procedure is complete, and the source cell may stop forwarding data, release information related to UE 852 (e.g., UE context), etc.

[0132] As mentioned above, Fig. 8A are provided as examples. Other examples may differ from those described in Fig. 8A Examples described.

[0133] Figure 8B 8 is a diagram illustrating an example 850 of load information communication for a conditional handover procedure according to various aspects of the present disclosure. As described above, the source cell may collect load information from target cells 1 and 2 and may communicate the load information to the UE. Thus, the UE may perform cell selection and / or beam selection based on the load information of the target cells 1 and 2. The load information communication procedure may be performed before and / or during the conditional handover procedure.

[0134] like Figure 8B As shown, the source cell may initiate a resource state request 862 and communicate it to the target cell 1 and the target cell 2. The resource state request 862 may include requests for load information from the target cell 1 and the target cell 2, respectively. Specifically, the requested load information may include radio resource usage information, such as GBR PRB and / or non-GBR PRB utilization and beam utilization information. The requested load information may also include per-service type radio resource usage information. The target cell 1 may respond by sending back a resource state response 866 including the requested load information of the target cell 1. Similarly, the target cell 2 may respond by sending back a resource state response 868 including the requested load information of the target cell 2. The source cell may collect load information from the target cells 1 and 2 and may send the load information to the UE 852. Specifically, the load information may be communicated to the UE 852 in the RRC reconfiguration 870. The UE 852 may then use the load information of the target cells 1 and 2 (and in some examples, the load information of the source cell) to perform cell selection and / or beam selection for conditional handover. For example, UE 852 may select a target cell with a lower load among target cells that meet the radio strength requirement.

[0135] Fig. 9 9 is a schematic diagram illustrating an example 900 of communication of Xn messages for handover negotiation according to various aspects of the present disclosure. Fig. 9 As shown, base stations 910 and 920 can communicate via an Xn interface. Each of base stations 910 and 920 can be an NR base station or an eLTE base station. The new Xn message can be used to negotiate a handover trigger change between NG-RAN base stations (e.g., base stations 910 and 920). Fig. 9 As shown, base station 910 may send a mobility change request 912 to base station 920. Mobility change request 912 may include one or more requests for handover of certain UEs between base stations. In response, base station 920 may send a mobility change response 914. Mobility change response 914 may include a response (e.g., yes or no) to the proposed modification. Thus, the new Xn message may allow the NG-RAN station to negotiate handover of UEs between base stations.

[0136] Fig.10 1 is a diagram illustrating an example process 1000 performed, for example, by a wireless communication device in accordance with various aspects of the present disclosure. The example process 1000 is an example of a wireless communication device, such as base station 102, performing a load information communication procedure.

[0137] At 1010, a wireless communication device (such as a base station, a CU or DU, a target cell, etc.) may send a resource status request to request load information related to load balancing. In some aspects, the load information includes one or more of the following: beam utilization information, per-service type radio resource usage information, supplemental uplink carrier load information, hardware load information, transport network layer load information, radio resource usage information, per-bandwidth portion load information, a number of user equipments (UEs) in connected mode, and a number of UEs in an inactive state.

[0138] At 1020, the wireless communication device may receive a resource status response including load information in response to the request. In some aspects, the load information may be received from another base station via an Xn or X2 communication interface. In other aspects, the load information may be received from another base station through a core network via an S1 or N2 communication interface. In some aspects, the load information may be communicated between a central unit and a distributed unit of a base station via an F1 communication interface to perform load balancing between the distributed units.

[0139] At 1030, the wireless communication device may selectively perform one or more of a handover procedure, a cell reselection procedure, a secondary node addition / modification procedure, or a bearer offloading procedure based on the load information. In some aspects, the load information may be sent to the UE for conditional handover target cell selection by the UE.

[0140] Although Fig.10 Example blocks of process 800 are shown, but in some aspects, process 800 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Figure 8. Additionally or alternatively, two or more blocks of process 800 may be performed in parallel.

[0141] Fig.11 1 is a diagram illustrating an example process 1100 performed, for example, by a UE in accordance with various aspects of the present disclosure. The example process 1100 is an example of a UE performing a conditional handover procedure based on load information. At 1110, the UE may receive a radio resource control (RRC) configuration including a set of target cells for a conditional handover procedure and load information of the target cells. In some aspects, the load information may include one or more of beam utilization information and per-service type radio resource usage information of the target cell.

[0142] At 1120, the UE may select a target cell from a set of target cells for a conditional handover procedure based at least on the load information of the target cell. In some aspects, a target cell having a lower load than one or more other target cells is selected from the set of target cells. At 1130, the UE may perform a conditional handover procedure to transfer from the source cell to the target cell.

[0143] although Fig.11 Example blocks of process 1100 are shown, but in some aspects, process 1100 may include Fig.11 Additional blocks, fewer blocks, different blocks, or blocks arranged in a different manner than those depicted in . Additionally or alternatively, two or more blocks of process 1100 may be performed in parallel.

[0144] The above disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of these aspects.

[0145] As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, and / or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and / or a combination of hardware and software.

[0146] Some aspects are described herein in conjunction with a threshold value. As used herein, satisfying a threshold value may refer to being greater than a threshold value, greater than or equal to a threshold value, less than a threshold value, less than or equal to a threshold value, equal to a threshold value, not equal to a threshold value, etc.

[0147] It is apparent that the systems and / or methods described herein can be implemented in various forms of hardware, firmware, and / or combinations of hardware and software. The actual dedicated control hardware or software code used to implement these systems and / or methods does not limit these aspects. Therefore, the operation and behavior of the systems and / or methods are described herein without reference to specific software code - it should be understood that software and hardware can be designed to implement the systems and / or methods based at least in part on the description herein.

[0148] Even if a specific combination of features is recorded in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features can be combined in a manner that is not specifically recorded in the claims and / or not specifically disclosed in the specification. Although each dependent claim listed below may directly rely on only one claim, the disclosure of various aspects includes the combination of each dependent claim with each other claim in the claim set. The phrase "at least one" mentioned in the list of items refers to any combination of these items, including single members. For example, "at least one of a, b or c" is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination of multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc and ccc, or any other ordering of a, b and c).

[0149] Unless explicitly stated, any element, action or instruction used herein should not be interpreted as critical or essential. In addition, as used herein, the articles "a" and "an" are intended to include one or more items and can be used interchangeably with "one or more". In addition, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.), and can be used interchangeably with "one or more". If only one item is expected, the phrase "only one" or similar language is used. In addition, as used herein, the terms "has", "have", "with", and / or similar terms are intended to be open terms. In addition, unless explicitly stated otherwise, the phrase "based on" is intended to mean "based at least in part on".

Claims

1. A method for wireless communication at a user equipment UE, comprising: receiving a radio resource control (RRC) configuration, the RRC configuration including a set of target cells for a conditional handover procedure and load information of the target cells; selecting a target cell from the set of target cells for the conditional handover procedure based at least on load information of the target cell; as well as The conditional handover procedure is performed to transfer from a source cell to the target cell.

2. The method according to claim 1, wherein: The load information includes one or more of beam utilization information and per-service type radio resource usage information of the target cell.

3. The method according to claim 1, wherein: The selecting includes selecting the target cell in the set of target cells that has a lower load than one or more other target cells.

4. A wireless communication device, the device comprising: means for receiving, at a user equipment UE, a radio resource control RRC configuration, the RRC configuration comprising a set of target cells for a conditional handover procedure and load information of the target cells; A component for selecting, at a user equipment UE, a target cell from the set of target cells for the conditional handover procedure based at least on load information of the target cell; as well as means for performing the conditional handover procedure at a user equipment UE to transfer from a source cell to the target cell.

5. The device according to claim 4, wherein: The load information includes one or more of beam utilization information and per-service type radio resource usage information of the target cell.

6. The apparatus according to claim 4, further comprising: Means for selecting, among the set of target cells, the target cell having a lower load than one or more other target cells.

7. A wireless communication device, the device comprising: Memory; as well as at least one processor coupled to the memory and configured to: Receiving a radio resource control RRC configuration at a user equipment UE, the RRC configuration including a set of target cells for a conditional handover procedure and load information of the target cells; Selecting, at the UE, a target cell from the set of target cells for the conditional handover procedure based at least on load information of the target cell; as well as The conditional handover procedure is performed at the UE to transfer from a source cell to the target cell.

8. The device according to claim 7, wherein: The load information includes one or more of beam utilization information and per-service type radio resource usage information of the target cell.

9. The apparatus of claim 7, the at least one processor further configured to select the target cell in the set of target cells that has a lower load than one or more other target cells.

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