Configuration Selection Extension for Layer 1 / Layer 2 Trigger Mobility

Abstract

Generally, the present subject matter relates to a configuration selection extension for layer 1 / layer 2 (L1 / L2) trigger mobility (LTM). In some embodiments, the configuration selection extension for LTM can include receiving, at a central unit control plane (CU-CP) of a base station, data associated with preparing an LTM handover (HO) configuration for at least one service for a user equipment (UE) from a first distributed unit (DU) of the base station, and after receiving the data, the CU-CP can include requesting, from a second DU, to prepare at least one LTM target cell configuration for HO of at least one service for the UE, considering the data.

Description

Technical Field

[0001] Cross - reference to related applications This application claims priority to Indian Patent Application No. 202221060195, filed on October 21, 2022, entitled "Method and system for configuration selection enhancements for Lower Layer Mobility", the entire content of which is incorporated herein by reference.

[0002] In certain embodiments, the present subject matter relates to a telecommunications system, and more particularly, to configuration selection enhancements for Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM).

Background Art

[0003] In today's world, cellular networks provide on - demand communication capabilities to individuals and enterprises. Generally, a cellular network is a wireless network that can be distributed over terrestrial areas called cells. Each such cell is served by at least one fixed - location transceiver called a cell site or base station. Each cell can use a different set of frequencies from its neighboring cells to avoid interference and provide improved services within each cell. When cells are combined together, they provide wireless coverage over a wide geographical area, thereby enabling a large number of mobile phones, and / or other wireless devices or portable transceivers to communicate with each other, as well as with some fixed transceiver and telephone anywhere in the network. Such communication is carried out via the base station and is achieved even when the mobile transceiver is moving through two or more cells during transmission. Major wireless communication providers have deployed such cell sites around the world, thereby enabling communication mobile phones and mobile computing devices to connect to the public switched telephone network and the public Internet.

[0004] A mobile phone is a portable phone that can receive and / or transmit phone and / or data communications via a cell site or transmission tower by using radio waves to transfer signals between mobile phones. Considering a large number of mobile phone users, the current mobile phone network provides limited shared resources. In that regard, cell sites and handsets can change frequencies and use low-power transmitters to enable simultaneous use of the network by more callers with less interference. Coverage by cell sites can depend on a specific geographical location and / or the number of users potentially using the network. For example, in a city, a cell site can have a range of up to about 1 / 2 mile, in rural areas, the range can be up to 5 miles, and in some areas, users can receive signals from cell sites up to 25 miles away.

[0005] The following are some examples of digital cellular technologies used by communication providers, namely, Global System for Mobile Communications for mobile communication (「GSM」), General Packet Radio Service (「GPRS」), cdmaOne, CDMA2000, Evolution - Data Optimized (「EV-DO」), GSM Enhanced Data Rates for GSM Evolution (「EDGE」), Universal Mobile Telecommunications System (「UMTS」), Digital Enhanced Cordless Telecommunications (「DECT」), Digital AMPS (「IS-136 / TDMA」), and Integrated Digital Enhanced Network (「iDEN」). Long Term Evolution, namely 4G LTE developed by the 3rd Generation Partnership Project (「3GPP(registered trademark)」) standards body, is a standard for wireless communication of high-speed data for mobile phones and data terminals. Currently, 5G standards are being developed and deployed. 3GPP cellular technologies such as LTE and 5G NR are evolved from early-generation 3GPP technologies such as GSM / EDGE and UMTS / HSPA digital cellular technologies, enabling increased capacity and speed by using different radio interfaces along with improvements to the core network.

[0006] A cellular network can be divided into a radio access network and a core network. The radio access network (RAN) may include network functions capable of handling radio layer communication processing. The core network may include network functions capable of handling upper layer communication, such as Internet Protocol (IP), transport layer, and application layer. In some cases, the RAN functions may be divided into a baseband unit function and a radio unit function. For example, a radio unit connected to a baseband unit via a fronthaul network can be responsible for lower layer processing of the radio physical layer, and the baseband unit can be responsible for upper layer radio protocols such as MAC, RLC, etc.

[0007] A base station for a 5G cellular network may include a central unit (CU), one or more distributed units (DUs) communicatively connected to the CU, and one or more radio units (RUs) each communicatively connected to at least one of the one or more DUs and each configured to be communicatively connected to one or more mobile phones and / or other user equipment (UE). The CU may be logically divided into a control plane part (CU-CP) and one or more user plane parts (CU-UP). During the process of a UE establishing a communication connection with a base station, the DU supporting the UE may change. In layer 1 / layer 2 (L1 / L2) trigger mobility (LTM) and multi-transmission and reception point (mTRP), the configuration preparation for handover from a serving cell to a target cell is always executed by the CU-CP, and its execution is carried out by the DU. This means that the CU-CP needs to be able to determine which configuration should be requested from the DU at a given point in time. In existing methods, there is a lack of awareness of configuration details in the CU, which makes it impossible for the CU-CP to select the configuration required from the target cell in the DU.

Summary of the Invention

[0008] In one embodiment, the subject matter relates to a computer-implemented method. The method may include receiving, at a centralized unit control plane (CU-CP) of a base station, data related to preparing a layer 1 / layer 2 trigger mobility (LTM) handover (HO) configuration for at least one service for a user equipment (UE) from a first distributed unit (DU) of the base station. The method may also include, after receiving the data, requesting, by the CU-CP, the second DU of the base station to prepare at least one LTM target cell configuration for HO of at least one service for the UE, considering the data.

[0009] The method may enable a configuration selection extension for LTM in the DU and enable the CU-CP to recognize the situation of the DU and which configuration is likely to succeed in the DU.

[0010] In one embodiment, the subject matter may include one or more of the following optional features.

[0011] In one embodiment, the data may include timing advance information for each of a plurality of cells of the DU. Further, the CU-CP may receive the data in a procedure for setting up an F1 communication interface between the CU-CP and the first DU, and / or the CU-CP may receive the data in an F1 setup request message transmitted from the first DU to the CU-CP, or the timing advance information may include average timing advance information of a given reference signal received power (RSRP) value for each of a plurality of beams or beam groups of a plurality of cells of the second DU, and the CU-CP may receive the average timing advance information from the first DU before the CU-CP receives a message from the first DU that a service change for the UE is required, and / or the CU-CP may receive the data periodically in a non-UE related procedure between the CU-CP and the second DU.

[0012] In one embodiment, receiving may include the CU-CP periodically receiving data from a first DU before receiving from the first DU a message that a service change for the UE is required, and the method may further include, at the CU-CP, constructing a HO policy using machine learning, at least in part based on the received data. Further, the data may include data regarding at least one of a type of the UE, a speed of the UE, at least one service accessed by the UE at the first DU, and dynamic handover between a first cell and a second cell, and / or the method may further include, at the CU-CP, receiving performance data regarding the service of the first DU to the UE from the first DU currently serving the UE for at least one service, and requesting may include requesting the second DU to prepare at least one LTM target cell, considering also the data received from the first DU.

[0013] In one embodiment, the first DU may include at least one cell, the data may include resource availability of at least one cell, and receiving may include the CU-CP periodically receiving resource availability from the first DU before receiving from the first DU, for at least one service, a message that a service change for the UE is required, and / or the resource availability may include availability in each of at least one cell for inter-cell beam management (ICBM), dynamic handover, multi-transmission and reception point (mTRP), and LTM serving cell change (SCC).

[0014] In one embodiment, requesting may include transmitting, from the CU-CP to the second DU, an instruction for a target cell configuration that is at least one of ICBM, dynamic handover, and LTM SCC.

[0015] In one embodiment, before the CU-CP receives from the first DU, which is currently providing service to the UE for at least one service, a message that a service change is required for the UE, the CU-CP can receive data from the first DU.

[0016] In one embodiment, the method may also include, at the CU-CP, selecting a target cell configuration based at least in part on the received data.

[0017] In one embodiment, the base station may have a non-agglomerated architecture.

[0018] In one embodiment, the base station may include a next-generation radio access network (NG-RAN) node including a gNodeB or an ng-eNodeB.

[0019] In one embodiment, the base station may include at least one processor and may also include at least one non-transitory storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to execute the method.

[0020] A non - transitory computer program product (i.e., a physically embodied computer program product) is also described, which stores instructions that, when executed by one or more data processors of one or more computing systems, cause at least one data processor to perform the operations herein. Similarly, a computer system is described that may include one or more data processors and a memory connected to the one or more data processors. The memory can store instructions, either temporarily or permanently, that cause at least one processor to perform one or more of the operations described herein. Further, the method may be implemented by one or more data processors within a single computing system or distributed across two or more computing systems. Such computing systems may be connected via one or more connections through which data and / or commands or other instructions, etc. can be exchanged, and this connection includes, but is not limited to, a connection via a network (such as the Internet, a wireless wide - area network, a local - area network, a wide - area network, a wired network, etc.) such as a direct connection between one or more of the plurality of computing systems.

[0021] Details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the following description. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims.

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate specific aspects of the subject matter disclosed herein and, together with the description, serve to explain some of the principles associated with the disclosed embodiments.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0047] The present subject matter can provide a system and method that can be implemented in a wireless communication system. Such a system can include various wireless communication systems, including a 5G new radio communication system, a long - term evolution communication system, and the like.

[0048] Generally, the present subject matter relates to a configuration selection extension for layer 1 / layer 2 (L1 / L2) trigger mobility (LTM).

[0049] Conventionally, to support L1 / L2 central cell changes (e.g., serving cell changes) in a non - aggregated gNB architecture, the configuration is done in the gNB - CU - CP, but it cannot be autonomously executed by the gNB - DU without further interaction with the upper layers. In LTM, and also in multi - transmit - receive point (mTRP), the configuration preparation for handover from the serving cell to the target cell is always executed by the CU - CP, and its execution is done by the DU. This means that the CU - CP needs to be able to determine which configuration to request from the DU at a given time. In existing methods, there is a lack of awareness of the configuration details in the CU, which makes it impossible for the CU - CP to select the configuration required from the target cell in the DU. The LTM configuration selection extension described herein can enable a configuration selection extension for LTM in the DU, and also enable the CU - CP to be aware of the DU's situation and which configurations are likely to succeed in the DU.

[0050] The 3GPP standards and / or the O - RAN Alliance standards may be relevant to one or more aspects of this subject matter.

[0051] One or more aspects of this subject matter may be incorporated into the transmitter and / or receiver components of a base station (e.g., gNodeB, eNodeB, etc.) within such a communication system. The following is a general discussion of the Long - Term Evolution communication system and the 5G New Radio communication system.

[0052] I. Long - Term Evolution Communication System Figures 1a - 1c and 2 illustrate an exemplary conventional Long Term Evolution (LTE) communication system 100 along with its various components. The LTE system or 4G LTE is governed by a standard for wireless communication of high - speed data for mobile phones and data terminals, as is commercially known. This standard is an evolution of GSM / EDGE (Global System for Mobile Communications / Enhanced Data Rates for GSM Evolution) as well as UMTS / HSPA (Universal Mobile Telecommunications System / High - Speed Packet Access) network technologies. This standard was developed by the 3GPP (3rd Generation Partnership Project).

[0053] As shown in Figure 1a, the system 100 can include an evolved Universal Terrestrial Radio Access Network (EUTRAN) 102, an evolved Packet Core (EPC) 108, and a Packet Data Network (PDN) 101, where the EUTRAN 102 and the EPC 108 provide communication between the user equipment 104 and the PDN 101. The EUTRAN 102 can include a plurality of evolved Node Bs (eNodeBs or ENODEBs or enodebs or eNBs) or base stations 106 (a, b, c) (as shown in Figure 1b) that provide communication capabilities to a plurality of user equipments 104 (a, b, c). The user equipment 104 can be a mobile phone, smartphone, tablet, personal computer, personal digital assistant (PDA), server, data terminal, and / or any other type of user equipment, and / or any combination thereof. The user equipment 104 can connect to the EPC 108, and ultimately to the PDN 101, via any of the eNodeBs 106. Typically, the user equipment 104 can connect to the eNodeB 106 that is closest in terms of distance. In the LTE system 100, the EUTRAN 102 and the EPC 108 cooperate to provide connectivity, mobility, and services for the user equipment 104.

[0054] Figure 1b shows further details of the network 100 shown in Figure 1a. As described above, the EUTRAN 102 includes a plurality of eNodeBs 106, also known as cell sites. The eNodeB 106 provides radio functions and performs important control functions including scheduling of air-link resources or radio resource management, active mode mobility or handover, and admission control for services. The eNodeB 106 is responsible for selecting which mobility management entity (such as the MME shown in Figure 1c) provides services to the user equipment 104 and protocol features such as header compression and encryption. The eNodeBs 106 that make up the EUTRAN 102 cooperate with each other for radio resource management and handover.

[0055] Communication between the user equipment 104 and the eNodeB 106 is performed via an air interface 122 (also known as the "LTE-Uu" interface). As shown in Figure 1b, the air interface 122 provides communication between the user equipment 104b and the eNodeB 106a. The air interface 122 uses orthogonal frequency division multiple access ("OFDMA") and single carrier frequency division multiple access ("SC-FDMA"), an OFDMA variant, on the downlink and uplink, respectively. OFDMA enables the use of multiple known antenna technologies such as multiple input multiple output ("MIMO").

[0056] The air interface 122 uses various protocols including radio resource control ("RRC") for signaling between the user equipment 104 and the eNodeB 106 and non-access stratum ("NAS") for signaling between the user equipment 104 and the MME (as shown in Figure 1c). In addition to signaling, user traffic is transferred between the user equipment 104 and the eNodeB 106. Both signaling and traffic in the system 100 are carried by physical layer ("PHY") channels.

[0057] A plurality of eNodeBs 106 can be interconnected with each other using the X2 interfaces 130 (a, b, c). As shown in FIG. 1b, the X2 interface 130a provides an interconnection between eNodeB 106a and eNodeB 106b, the X2 interface 130b provides an interconnection between eNodeB 106a and eNodeB 106c, and the X2 interface 130c provides an interconnection between eNodeB 106b and eNodeB 106c. The X2 interface can be established between two eNodeBs to provide signal exchange, and the signal exchange can include information related to load or interference, as well as information related to handover. The eNodeB 106 communicates with the evolved packet core 108 via the S1 interfaces 124 (a, b, c). The S1 interface 124 can be split into two interfaces, one for the control plane (shown as the control plane interface (S1-MME interface) 128 in FIG. 1c) and the other for the user plane (shown as the user plane interface (S1-U interface) 125 in FIG. 1c).

[0058] The EPC 108 establishes and enforces a quality of service (「QoS」) for user services and enables the user equipment 104 to maintain a consistent Internet Protocol (「IP」) address while in motion. Note that each node within the network 100 has its own IP address. The EPC 108 is designed to interact with legacy wireless networks. The EPC 108 is also designed to separate the control plane (i.e., signaling) and the user plane (i.e., traffic) in the core network architecture, which allows for more flexibility in embodiments, as well as independent scalability of control and user data functions.

[0059] The architecture of the EPC108 is dedicated to packet data and is shown in more detail in FIG. 1c. The EPC108 includes a Serving Gateway (S-GW) 110, a PDN Gateway (P-GW) 112, a Mobility Management Entity (MME) 114, a Home Subscriber Server (HSS) 116 (subscriber database for the EPC108), and a Policy Control and Charging Rules Function (PCRF) 118. Some of these (such as the S-GW, P-GW, MME, and HSS) are often combined into nodes according to the manufacturer's implementation.

[0060] The S-GW 110 functions as an IP packet data router and is the bearer path anchor for user equipment within the EPC108. Thus, when a user equipment moves from one eNodeB 106 to another during a mobility operation, the S-GW 110 remains the same and the bearer path towards the EUTRAN 102 is switched to communicate with the new eNodeB 106 serving the user equipment 104. If the user equipment 104 moves to the domain of another S-GW 110, the MME 114 will transfer all of the user equipment's bearer paths to the new S-GW. The S-GW 110 establishes bearer paths for the user equipment to one or more P-GWs 112. When downstream data is received for an idle user equipment, the S-GW 110 buffers the downstream packets and requests the MME 114 to identify and re-establish the bearer path to and through the EUTRAN 102.

[0061] P-GW 112 is a gateway between the EPC 108 (and the user equipment 104 and the EUTRAN 102) and the PDN 101 (shown in FIG. 1a). The P-GW 112 functions as a router for user traffic and executes functions on behalf of the user equipment. These include IP address allocation for the user equipment, packet filtering of downstream user traffic to ensure that downstream user traffic is placed on an appropriate bearer path, and implementation of downstream QoS including data rate. Depending on the services used by the subscriber, there may be multiple user data bearer paths between the user equipment 104 and the P-GW 112. The subscriber can use services on PDNs served by different P-GWs, in which case the user equipment has at least one bearer path established for each P-GW 112. During a handover of the user equipment from one eNodeB to another, if the S-GW 110 is also changing, the bearer path from the P-GW 112 is switched to the new S-GW.

[0062] The MME 114 manages user equipment 104 within the EPC 108, including performing subscriber authentication, maintaining a context for the authenticated user equipment 104, establishing data bearer paths within the network for user traffic, and tracking the location of idle mobiles not detached from the network. In the case of an idle user equipment 104 that needs to reconnect to the access network to receive downstream data, the MME 114 initiates paging to identify the location of the user equipment and re-establishes the bearer path to and through the EUTRAN 102. The MME 114 for a particular user equipment 104 is selected by the eNodeB 106 where the user equipment 104 initiates system access. The MME is typically part of a set of MMEs within the EPC 108 for load sharing and redundancy purposes. In establishing the user's data bearer path, the MME 114 is responsible for selecting the P-GW 112 and the S-GW 110, which form the termination of the data path through the EPC 108.

[0063] PCRF 118 is responsible for controlling policy control decision-making and the flow-based charging functionality within the Policy Control Enforcement Function (the "PCEF") resident in the P-GW 110. The PCRF 118 provides QoS authorization (QoS Class Identifier (the "QCI") and bit rate), which determines how a certain data flow is handled within the PCEF and ensures that this is in accordance with the user's subscription profile.

[0064] As described above, the IP service 119 is provided by the PDN 101 (as shown in Figure 1a).

[0065] FIG. 1d shows an exemplary structure of eNodeB 106. eNodeB 106 may include at least one remote radio head ( "RRH") 132 (typically, three RRHs 132 may exist) and a baseband unit ( "BBU") 134. The RRH 132 may be connected to an antenna 136. The RRH 132 and the BBU 134 may be connected using an optical interface that complies with the standard specifications of a common public radio interface ( "CPRI") / extended CPRI ( "eCPRI") 142, either using a custom control and user plane construction method specific to the RRH or using an O-RAN Alliance compliant control and user plane construction method. The operation of eNodeB 106 can be characterized using the following standard parameters (and specifications), namely, high-frequency bands (band 4, band 9, band 17, etc.), bandwidths (5, 10, 15, 20 MHz), access methods (downlink: OFDMA, uplink: SC-OFDMA), antenna technologies (single-user and multi-user MIMO, uplink: single-user and multi-user MIMO), number of sectors (maximum 6), maximum transmission speeds (downlink: 150 Mb / s, uplink: 50 Mb / s), S1 / X2 interfaces (1000Base-SX, 1000Base-T), and mobile environments (maximum 350 km / h). The BBU 134 can be responsible for digital baseband signal processing, termination of S1 lines, termination of X2 lines, call processing, and monitoring control processing. IP packets received from the EPC 108 (not shown in FIG. 1d) can be modulated into digital baseband signals and transmitted to the RRH 132. Conversely, digital baseband signals received from the RRH 132 can be demodulated into IP packets for transmission to the EPC 108.

[0066] The RRH 132 can transmit and receive wireless signals using the antenna 136. The RRH 132 can convert digital baseband signals from the BBU 134 into radio frequency (RF) signals (using the converter ("CONV") 140) and power-amplify them (using the amplifier ("AMP") 138) for transmission to the user equipment 104 (not shown in FIG. 1d). Conversely, RF signals received from the user equipment 104 are amplified (using the AMP 138) and converted into digital baseband signals (using the CONV 140) for transmission to the BBU 134.

[0067] FIG. 2 shows additional details of an exemplary eNodeB 106. The eNodeB 106 includes multiple layers, namely, an LTE layer 1 202, an LTE layer 2 204, and an LTE layer 3 206. The LTE layer 1 includes the physical layer ("PHY"). The LTE layer 2 includes the media access control ("MAC"), radio link control ("RLC"), and packet data convergence protocol ("PDCP"). The LTE layer 3 includes various functions and protocols including radio resource control ("RRC"), dynamic resource allocation, eNodeB measurement configuration and provisioning, radio admission control, connection mobility control, and radio resource management ("RRM"). The RLC protocol is an automatic repeat request ("ARQ") fragmentation protocol used over the cellular air interface. The RRC protocol processes the LTE layer 3 control plane signaling between the user equipment and the EUTRAN. The RRC includes functions for connection establishment and release, broadcast of system information, radio bearer establishment / reconfiguration and release, RRC connection mobility procedures, paging notification and release, and outer loop power control. The PDCP performs IP header compression and decompression, transfer of user data, and maintenance of the sequence number of the radio bearer. The BBU 134 shown in FIG. 1d may include the LTE layers L1 - L3.

[0068] One of the main functions of eNodeB 106 is radio resource management, which includes scheduling of uplink and downlink air interface resources for user equipment 104, control of bearer resources, and admission control. eNodeB 106, as an agent for EPC 108, is responsible for transferring paging messages used to identify the location of a mobile when it is idle. eNodeB 106 also communicates common control channel information over the air, communicates header compression, encryption and decryption of user data sent over the air, and establishes handover reports and trigger criteria. As described above, eNodeB 106 can cooperate with other eNodeB 106s via the X2 interface for the purposes of handover and interference management. eNodeB 106 communicates with the MME of the EPC via the S1-MME interface and communicates with the S-GW using the S1-U interface. Further, eNodeB 106 exchanges user data with the S-GW via the S1-U interface. eNodeB 106 and EPC 108 have a many-to-many relationship to support load sharing and redundancy between the MME and the S-GW. eNodeB 106 selects an MME from a group of MMEs so that the load can be shared by multiple MMEs to avoid congestion.

[0069] II. 5G NR Wireless Communication Network In one embodiment, the subject matter relates to a 5G New Radio (NR) communication system. 5G NR is the next communication standard beyond the 4G / IMT-Advanced standard. The 5G network provides higher capacity than current 4G, enabling more mobile broadband users per unit area and allowing for consumption of more and / or unlimited amounts of data in gigabytes per month and per user. This can enable users to stream high-definition media for hours a day using a mobile device, even when it is not possible to do so with a Wi-Fi network. The 5G network has improved support for device-to-device communication, lower cost, lower latency and lower battery consumption than 4G devices. Such a network has data rates of tens of megabits per second for a large number of users, a data rate of 100 Mb / s for a metropolitan area, 1 Gb / s simultaneously to users within a limited area (e.g., an office floor), a large number of simultaneous connections for wireless sensor networks, enhanced spectral efficiency, improved coverage, enhanced signaling efficiency, a latency of 1 to 10 ms, and reduced latency compared to existing systems.

[0070] FIG. 3 shows an exemplary virtual radio access network 300. The network 300 can provide communication between various components including a base station (e.g., eNodeB, gNodeB) 301, a radio device 303, a central unit 302, a digital unit 304, and a radio device 306. The components in the system 300 can be communicatively connected to the core using a backhaul link 305. The central unit (“CU”) 302 can be communicatively connected to the distributed unit (“DU”) 304 using a midhaul connection 308. The radio unit (“RU”) component 306 can be communicatively connected to the DU 304 using a fronthaul connection 310.

[0071] In one embodiment, CU302 can provide intelligent communication functions to one or more DU units 304. The units 302, 304 can include one or more base stations, macro base stations, micro base stations, remote radio heads, etc., and / or any combination thereof.

[0072] In a lower layer split architecture environment, the CPRI bandwidth requirement for NR can be several hundred Gb / s. CPRI compression can be implemented at the DU and RU (as shown in FIG. 3). In a 5G communication system, the compressed CPRI over an Ethernet frame is referred to as eCPRI, which is the recommended fronthaul network. This architecture can enable the standardization of fronthaul / midhaul, which can include upper layer split (e.g., option 2 or option 3-1 (upper / lower RLC split architecture)) and fronthaul using an L1 split architecture (option 7).

[0073] In one embodiment, a lower layer split architecture (e.g., option 7) can include a receiver in the uplink, joint processing over multiple transmission points (TPs) for both DL / UL, and transport bandwidth and latency requirements to facilitate deployment. Further, the lower layer split architecture of the present subject matter can include a split between cell-level processing and user-level processing, which can include cell-level processing at a remote unit ("RU") and user-level processing at the DU. Further, using the lower layer split architecture of the present subject matter, frequency domain samples can be transported via an Ethernet fronthaul, and the frequency domain samples can be compressed for reduced fronthaul bandwidth.

[0074] FIG. 4 shows an exemplary communication system 400 that can implement 5G technology and provide its users with the use of higher frequency bands (e.g., greater than 10 GHz). The system 400 can include a macrocell 402 and small cells 404, 406.

[0075] Mobile device 408 can be configured to communicate with one or more of small cells 404, 406. System 400 can enable the split of the control plane (C-plane) and user plane (U-plane) between macro cell 402 and small cells 404, 406, and the C-plane and U-plane utilize different frequency bands. Specifically, small cells 404, 406 can be configured to utilize a higher frequency band when communicating with mobile device 408. Macro cell 402 can utilize the existing cellular band for C-plane communication. Mobile device 408 can be communicatively connected via U-plane 412, where a small cell (e.g., small cell 406) can provide a higher data rate and a more flexible / cost / energy-efficient operation. Macro cell 402 can maintain good connectivity and mobility via C-plane 410. Further, in some cases, LTE and NR can be transmitted on the same frequency.

[0076] FIG. 5a shows an exemplary 5G wireless communication system 500 according to an embodiment of the present subject matter. System 500 can be configured to have a lower layer split architecture according to Option 7-2. System 500 can include a core network 502 (e.g., 5G core) and one or more gNodeBs (or gNBs), and the gNB can have a centralized unit gNB-CU. The gNB-CU can be logically split into a control plane part gNB-CU-CP504 and one or more user plane parts gNB-CU-UP506. The control plane part 504 and the user plane part 506 can be configured to be communicatively connected using an E1 communication interface 514 (as defined in the 3GPP standard). The control plane part 504 can be configured to be responsible for executing the RRC and PDCP protocols of the radio stack.

[0077] The control plane part 504 and the user plane part 506 of the gNB's central unit can be configured to be communicatively connected to one or more distributed units (DUs) 508, 510 according to the upper layer split architecture. The distributed units 508, 510 can be configured to execute the upper parts of the RLC, MAC, and PHY layer protocols of the radio stack. The control plane part 504 can be configured to be communicatively connected to the distributed units 508, 510 using the F1-C communication interface 516, and the user plane part 506 can be configured to be communicatively connected to the distributed units 508, 510 using the F1-U communication interface 518. The distributed units 508, 510 can be connected to one or more remote radio units (RUs) 512 via a fronthaul network 520 (which may include one or more switches, links, etc.), which in turn communicates with one or more user devices (not shown in FIG. 5a). The remote radio unit 512 can be configured to execute the lower part of the PHY layer protocol and provide antenna capabilities to the remote unit for communication with user devices (similar to the above description related to FIGS. 1a-2).

[0078] FIG. 5b shows an exemplary layer architecture 530 of the split gNB. The architecture 530 can be implemented within the communication system 500 shown in FIG. 5a, which can be configured as a virtualized and disaggregated radio access network (RAN) architecture, whereby the layer L1, L2, L3, and radio processing can be virtualized and disaggregated within the central unit, distributed unit, and radio unit. As shown in FIG. 5b, the gNB-DU 508 can be communicatively connected to the gNB-CU-CP control plane part 504 (also shown in FIG. 5a) and the gNB-CU-UP user plane part 506. Each of the components 504, 506, 508 can be configured to include one or more layers.

[0079] The gNB-DU508 may include the RLC, MAC, and PHY layers, as well as various communication sub-layers. These may include the F1 application protocol (F1-AP) sub-layer, the GPRS tunneling protocol (GTPU) sub-layer, the stream control transmission protocol (SCTP) sub-layer, the user datagram protocol (UDP) sub-layer, and the internet protocol (IP) sub-layer. As described above, the distributed unit 508 can be communicatively connected to the control plane portion 504 of the central unit, and the central unit may also include the F1-AP, SCTP, and IP sub-layers, as well as the radio resource control and PDCP control (PDCP-C) sub-layer. Further, the distributed unit 508 can also be communicatively connected to the user plane portion 506 of the gNB's central unit. The user plane portion 506 may include the service data adaptation protocol (SDAP), PDCP user (PDCP-U), GTPU, UDP, and IP sub-layers.

[0080] Figure 5c shows an exemplary functional split in the gNB architecture shown in Figures 5a-5b. As shown in Figure 5c, the gNB-DU508 can be communicatively connected to the gNB-CU-CP504 and the gNB-CU-UP506 using the F1-C communication interface. The gNB-CU-CP504 and the gNB-CU-UP506 can be communicatively connected using the E1 communication interface. The upper part of the PHY layer (or layer 1) can be executed by the gNB-DU508, and the lower part of the PHY layer can be executed by the RU (not shown in Figure 5c). As shown in Figure 5c, the RRC and PDCP-C parts may be executed by the control plane portion 504, and the SDAP and PDCP-U parts may be executed by the user plane portion 506.

[0081] Some of the functions of the PHY layer in a 5G communication network include error detection on the transport channel and indication to the upper layer, FEC encoding / decoding of the transport channel, hybrid ARQ soft combining, rate matching of the coded transport channel to the physical channel, mapping of the coded transport channel to the physical channel, power weighting of the physical channel, modulation and demodulation of the physical channel, frequency and time synchronization, radio characteristic measurement and indication to the upper layer, MIMO antenna processing, digital and analog beamforming, RF processing, and other functions.

[0082] The MAC sublayer of layer 2 can perform beam management, random access procedures, mapping between logical channels and transport channels, concatenation of multiple MAC service data units (SDUs) belonging to one logical channel into a transport block (TB), multiplexing / demultiplexing of SDUs belonging to logical channels to / from the TB passed between the physical layer on the transport channel, scheduling information reporting, error correction by HARQ, priority handling between logical channels of one UE, priority handling between UEs by dynamic scheduling, transport format selection, and other functions. The functions of the RLC sublayer can include transfer of upper layer packet data units (PDUs), error correction by ARQ, rearrangement, duplication, and protocol error detection of data PDUs, reestablishment, etc. The PDCP sublayer can be responsible for transfer of user data, various functions during the reestablishment procedure, retransmission of SDUs, SDU discard in the uplink, transfer of control plane data, etc.

[0083] The RRC sublayer of layer 3 can perform broadcast of system information to the NAS and AS, establishment, maintenance, and release of RRC connections, security, establishment, configuration, maintenance, and release of point-to-point radio bearers, mobility functions, reporting, and other functions.

[0084] III. Configuration Selection Extension for LTM Generally, a non - centralized architecture is defined in 3GPP which decomposes a gNodeB (gNB) into multiple logical entities. Similarly, a single DU can host multiple cells. Currently, according to 3GPP specifications, a single DU can host up to 512 LTM target cells. As described above, gNB - CU - CP hosts the PDCP layer and the RRC layer, while gNB - DU hosts the RLC layer, the MAC layer, and the PHY layer. The scheduling operation is performed at the gNB - DU.

[0085] Conventionally, to support L1 / L2 - centric cell - to - cell changes (e.g., serving cell change) in a non - centralized gNB architecture, the configuration is performed at the gNB - CU - CP, but it cannot be autonomously executed by the gNB - DU without further interaction with the upper layers. In LTM, and also in multi - transmit - receive - point (mTRP), the configuration preparation for handover from a serving cell to a target cell is always performed by the CU - CP and its execution is performed by the DU. This means that the CU - CP needs to be able to determine which configuration should be requested from the DU at a given point in time. In the existing methods, there is a lack of awareness of the configuration details in the CU, which makes it impossible for the CU - CP to select the configuration required from the target cells in the DU. The configuration selection extension for LTM described herein can enable a configuration selection extension for LTM in the DU and also enable the CU - CP to be aware of the DU's situation and which configurations are likely to succeed in the DU.

[0086] Layer 1 / Layer 2 Trigger Mobility (LTM) is an updated term for Lower Layer Mobility (LLM). RAN2 has agreed on the definition of LTM. Generally, LTM is a mobility procedure that enables the network to switch a UE from a source cell to a target cell without necessarily requiring reconfiguration by sync. In particular, based on the received L1 measurement values, the network can indicate, in L2 signaling (e.g., messages such as MAC CE), the beam to which the LTM candidate cell belongs for the UE to execute the LTM cell switching procedure. The UE is provided with at least one LTM candidate cell configuration by the network before executing the LTM cell switching procedure.

[0087] In certain embodiments of the present subject matter, a base station (e.g., a next-generation RAN (NG-RAN) node such as a gNodeB, eNodeB, or gNodeB in FIG. 5a) of a wireless communication system (e.g., a 5G wireless communication system, a 6G or later-generation wireless communication system, etc.) can have a non-agglomerated architecture that includes one gNB-CU-CP (e.g., gNB-CU-CP 504 in FIGS. 5a-5c), two or more CU-UPs (e.g., gNB-CU-UP 506 in FIGS. 5a-5c), and a gNB-DU (e.g., gNB-DU 508, 510 in FIGS. 5a-5c). The base station can be configured to provide a configuration selection extension for LTM.

[0088] Figure 6a shows an exemplary system 600 configured to enable configuration selection expansion for LTM. The base station 602 in this illustrated embodiment is a gNB configured to be in a 5G wireless communication system similar to the 5G wireless communication system 500 of FIG. 5a described above, but other base stations can be configured similarly and can be used when providing configuration selection expansion for LTM. In the illustrated embodiment of FIG. 6a, the base station 602 includes a plurality of CU-UPs 606a, 606b, 606c. The base station 602 includes three CU-UPs 606a, 606b, 606c in this illustrated embodiment, but can include another plurality of CU-UPs. The CU of the base station 602 including the plurality of CU-UPs 606a, 606b, 606c is configured to be communicatively connected to a core network (not shown in FIG. 6a), for example, the 5GC 502 of FIG. 5a, etc.

[0089] The CU of the base station 602 also includes a CU-CP 604 configured to be communicatively connected to the user plane portions 606a, 606b, 606c of the CU using an E1 communication interface 614. The E1 interface 614 includes three communication links in this illustrated embodiment to reflect that there are three CU-UPs 606a, 606b, 606c to which the CU-CP 604 can communicate.

[0090] The base station 602 also includes a plurality of DUs 608, 610. The base station 602 includes two DUs 608, 610 in this illustrated embodiment, but can include another plurality of DUs. The CU-CP 604 is configured to be communicatively connected to the DUs 608, 610 using an F1-C communication interface 616. The CU-UPs 606a, 606b, 606c are configured to be communicatively connected to the DUs 608, 610 using an F1-U communication interface 618. The F1-U interface 618 associated with each of the DUs 608, 610 includes three communication links in this illustrated embodiment to reflect that there are three CU-UPs 606a, 606b, 606c to which each DU 608, 610 can communicate.

[0091] The base station 602 also includes a plurality of RUs 612. The base station 602 includes five RUs 612 in this illustrated embodiment, but can include another plurality of RUs. The RUs 612 are configured to be communicatively connected to the DUs 608, 610 via the fronthaul network 620. Further, each of the RUs 612 is configured to be communicatively connected to one or more UEs 622. In this illustrated embodiment, two of the RUs 612 are shown to be communicatively connected to one UE 622, two of the RUs 612 are shown to be communicatively connected to two UEs 622, and one of the RUs 612 is shown to be communicatively connected to three UEs 622, but each of the RUs 612 can be connected to a different number of UEs, either the same as or different from any of the other RUs 612.

[0092] Secure L1 / L2 centered inter-cell mobility execution can be configured to occur when one of the UEs communicatively connected to the base station 602 is handed off from one of the DUs 608, 610 of the base station 602 to the other of the DUs 608, 610 of the same base station 602. One of the DUs 608, 610 currently providing service to the UE 622 is referred to as the "serving DU" because it is currently providing service to the UE 622. One of the DUs 608, 610 to which the service of the UE is being handed off is referred to as the "target DU" because it is targeted to provide service to the UE 622.

[0093] A system can be configured to perform secure L1 / L2 centered inter-cell mobility and is further described with respect to FIG. 6b. FIG. 6b shows the CU-CP 604 and CU-UPs 606a, 606b, 606c of FIG. 6a, and in the illustrated embodiment of FIG. 6b, the base station 602 includes three or more DUs. In the illustrated embodiment of FIG. 6b, the base station 602 includes 66 DUs. Three of the DUs 628a, 628b, 628c are macro cells (labeled macro1, macro2, and macro3 in FIG. 6b), and 63 of the DUs 626 are small cells (nine of which are labeled gNB-DU10, gNB-DU20, gNB-DU30, gNB-DU40, gNB-DU50, gNB-DU60, gNB-DU70, gNB-DU80, and gNB-DU90 in FIG. 6b). The base station 602 may include a different number of macro cells and / or a different number of small cells. Twenty-one of the small cell DUs 626, including macro1 DU 628a, macro2 DU 628b, and gNB-DU10, gNB-DU20, and gNB-DU30, are configured to be served by a first CU-UP 606a (labeled CU-UP1 in FIG. 6b). Twenty-one of the small cell DUs 626, including macro1 DU 628a, macro2 DU 628b, macro3 DU 628c, and gNB-DU40, gNB-DU50, and gNB-DU60, are configured to be served by a second CU-UP 606b (labeled CU-UP2 in FIG. 6b). Twenty-one of the small cell DUs 626, including macro2 DU 628b, macro3 DU 628c, and gNB-DU70, gNB-DU80, and gNB-DU90, are configured to be served by a third CU-UP 606c (labeled CU-UP3 in FIG. 6b).

[0094] In the embodiment shown in FIG. 6b, each CU-UP 606a, 606b, 606c provides services to a subset of DUs 626, 628a, 628, 628c for all services. However, the CU-UP can provide services to all DUs of the base station for one service (e.g., enhanced mobile broadband (eMBB)), while providing services to a subset of DUs for another service (e.g., vehicle-to-vehicle / vehicle-to-infrastructure (V2X) or ultra-reliable low-latency communication (URLLC)).

[0095] FIG. 7a shows an exemplary method 700 according to an embodiment of the present subject matter. The method 700 of FIG. 7a is described with respect to the exemplary system 800 shown in FIGS. 8a-8d, but can be similarly implemented in other systems, such as the systems 100 of FIGS. 1a-1c and FIG. 2, the system 400 of FIG. 4, the system 500 of FIG. 5a, the systems of FIGS. 6a and 6b, etc. Although the system 800 of FIGS. 8a-8d is a 5G system, as described above, the configuration selection extensions for LTM described herein can be implemented in other types of wireless communication systems, such as an LTE wireless communication system or a wireless communication system of the 6G or later generations. Although the various elements of FIGS. 8a-8d are numbered as consecutive steps, such numbering is not intended to indicate that only these numbered steps in this consecutive order can be executed within the system 800. One or more additional steps may be present before and / or after any one or more of the sequentially numbered steps shown in FIGS. 8a-8d.

[0096] In system 800, a UE (e.g., UE 104 in FIGS. 1a - 1c, UE 622 in FIG. 6a, etc.) (not shown in FIGS. 8a - 8d) is configured with an LTM having one or more target cells within one or more DUs 802, 804 of a base station, e.g., a gNB (e.g., gNodeB in FIG. 5a, gNodeB 624 in FIGS. 6a and 6b, etc.). Two or more UEs can be communicatively connected to the base station, and / or the base station can include three or more DUs. The base station of system 800 also includes a CU - CP 806 (e.g., gNB - CU - CP 504 in FIGS. 5a - 5c, CU - CP 604 in FIGS. 6a and 6b, etc.), and a CU including one or more CU - UPs (e.g., gNB - CU - UP 506 in FIGS. 5a - 5c, CU - UP 606a, 606b, 606c in FIGS. 6a and 6b, etc.) (not shown in FIGS. 8a - 8d), and a plurality of RUs (e.g., RU 512 in FIG. 5a, RU 612 in FIG. 6a, etc.) (not shown in FIGS. 8a - 8d). The UE is currently served by the first DU 802 of the base station. Further, the base station in FIGS. 8a - 8d is communicatively connected to a core network (e.g., EPC 108 in FIGS. 1a - 1c and 2, 5GC 502 in FIG. 5a, etc.) (not shown in FIGS. 8a - 8d).

[0097] As shown in FIG. 7a, an F1 communication interface is set up (702) between a first DU (labeled "gNB-DU1" in FIGS. 8a-8d) 802 and a CU-CP 806, and an F1 communication interface is set up (704) between a second DU (labeled "gNB-DU2" in FIGS. 8a-8d) 802 and the CU-CP 806. The F1 communication interface can be set up in accordance with 3GPP specifications (702, 704). FIG. 7a shows that the F1 communication interface is set up (702) between the first DU 802 and the CU-CP 806 before the F1 communication interface is set up between the second DU 804 and the CU-CP 806, but the F1 communication interface can be set up (704) between the second DU 806 and the CU-CP 806 before the F1 communication interface is set up (702) between the first DU 802 and the CU-CP 806.

[0098] During use of the first DU 802, the first DU 802 can provide at least one service to the UE. Method 700 shows an embodiment of an inter-DU LTM serving cell change scenario that includes the first DU (also referred to herein as the "serving DU") 802 determining (706) that a serving cell change is required for the UE. The determination (706) of the serving DU can include the serving DU 802 analyzing an intra-frequency L1 measurement report transmitted by the UE to the serving DU 802 in accordance with 3GPP specifications. According to 3GPP specifications, the intra-frequency L1 measurement report can include layer 1 (L1) measurement values that can be analyzed by the first DU 802 when making a radio resource control decision, which can include a serving cell change in which the UE is to be served by a DU other than the first DU 802, e.g., the second DU 804, for at least one service.

[0099] In response to determining that a serving cell change should occur (706), the serving DU 802 notifies the UE of the serving cell change (708). The notification to the UE may include the serving DU 802 transmitting a serving cell change command, such as a MAC CE, to the UE.

[0100] Also, in response to determining that a cell service change should occur, the serving DU 804 notifies the CU-CP 806 that a serving cell change has occurred for the UE (708). Thus, the notification (708) can identify the UE to the CU-CP 806 using an identifier according to 3GPP specifications, etc., known to the serving DU 802 that uniquely identifies the UE to the CU-CP 806. The notification 708 to the CU-CP 806 may include the serving DU 802 transmitting a serving cell change notification message to the CU-CP 806 using the previously set up (702) F1 communication interface. The serving cell change notification message may include cell identification information (ID) that uniquely identifies the UE that has undergone the serving cell change.

[0101] In response to receiving a serving cell change command from the serving DU 802, the UE can transmit a Radio Resource Control (RRC) reconfiguration positive acknowledgment message to the CU-CP 806. The CU-CP 806 will come to recognize from the RRC reconfiguration positive acknowledgment message that the UE uniquely identified to the CU-CP 806 by the serving DU 802 approves the completion of a normal serving cell change.

[0102] Also, in response to receiving the layer 3 RRC measurement configuration, the UE can transmit an RRC measurement report to the CU-CP 806 in accordance with the 3GPP standard. According to the 3GPP standard, the RRC measurement report may include layer 3 (L3) measurement values that can be analyzed by the CU-CP 806 when making resource control decisions, which may include determining to prepare at least one target cell for LTM such that at least one target cell from the target DU 804 can serve the UE instead of the serving DU 804 for at least one service.

[0103] In response to determining to prepare at least one target cell for LTM, the CU-CP 806 selects a configuration for at least one target cell for LTM (710). The configuration can be selected using data previously received by the CU-CP 806 as further discussed below (710).

[0104] As shown in FIGS. 8a - 8d, in these illustrated embodiments, each of the at least one target cell is an inter-DU target cell, e.g., a part of a DU different from the serving DU 802 that provides services to each of the DUs 802, 804 by the same CU (e.g., the CU including the CU-CP 806). Also, in these illustrated embodiments, since there are only two gNB-DUs, the at least one target cell includes only the target DU 804, but as described above, the base station can include three or more target cells. Currently, according to the 3GPP standard, up to eight LTM target cells can be prepared for a given UE.

[0105] Preparing at least one target cell for LTM may include notifying at least one target DU804 that the CU-CP806 may later be notified to start providing services to the UE for at least one service by at least one target DU804. Thus, the target DU804 can reserve the resources required for the UE. As shown in FIG. 7a, in this illustrated embodiment, notifying at least one target cell that is only the target DU804 may include the CU-CP806 requesting the target DU804 to prepare at least one target cell according to the prepared configuration. The request may include the CU-CP806 sending a UE context setup request message to the target DU804 according to 3GPP specifications using a previously set up (704) F1 communication interface.

[0106] In one embodiment, the CU-CP806 can select the configuration of at least one target cell for LTM using data received from at least one of the DUs802, 804 during the F1 setup procedure in which the F1 communication interface is set up between the DU and the CU-CP806. Handover (HO) from one cell of a base station's DU to another cell of another base station's DU is only performed after the F1 communication interface is set up with each of the DUs. Thus, by the CU-CP806 receiving HO-related data during the F1 setup procedure, it can be ensured that the CU-CP806 has HO-related data on hand before the need for HO arises.

[0107] In some embodiments, such as those illustrated in FIGS. 7b and 8a, the HO-related data received by the CU-CP 806 during the F1 setup includes timing advance information for one or more cells of the DU. The timing advance (TA) refers to the time offset at the UE between the start of the received downlink subframe and the transmitted uplink subframe. This offset at the UE is necessary to ensure that the downlink and uplink subframes are synchronized at the base station serving the US. This is a MAC layer (layer 2) control element (CE) from the base station to the UE that is used when controlling the uplink, for example, the signal transmission timing from the UE to the base station.

[0108] Since CU-CP806 knows the TA information for one or more cells of the first DU and for one or more cells of the second DU, CU-CP806 can determine whether each of at least one target cell, e.g., one or more cells of the second DU804, is a candidate for random access channel layer less (RACH less) HO from the serving DU802 based on whether the TA of the target cell is 0 or whether the TA of the serving cell is the same as the TA of the target cell. If the TA of the target cell is 0 or the TA of the serving cell is the same as the TA of the target cell, the target cell is a candidate for RACH less HO. Thus, CU-CP806 can request (712) at least one target cell of the second DU804 to prepare itself for RACH less HO if possible, or to prepare itself for RACH based HO otherwise. Thus, a HO from one cell of the serving DU802 to another cell of the target DU804 may take less time because a HO from the serving cell to one of at least one target cell already has been prepared in each of the one or more target cells to include either a contention free RACH procedure (for RACH less HO) or a contention based RACH procedure (for RACH based HO). Thus, the handover latency is reduced, thereby reducing the user plane interruption time.

[0109] As described above, an F1 communication interface is set up (702, 704) between CU-CP806 and each of the first and second DUs 802, 804. As shown in FIGS. 7b and 8a, setting up an F1 communication interface (702, 722) between the first DU 802 and CU-CP806 includes the serving DU 802 sending an F1: Setup Request (808) to CU-CP806 that includes TA information for all beams / beam groups for each cell of the serving DU 802. The serving DU 802 is shown in FIG. 8a as having a plurality of cells including Cell1, Cell2, etc., but the serving DU 802 can include a single cell or can include two or more cells. In response to receiving the F1: Setup Request from the serving DU 802, CU-CP806 sends an F1: Setup Response to the serving DU 802 (810).

[0110] As also shown in FIGS. 7b and 8a, in the F1 setup procedure where an F1 communication interface is set up (704, 724) between CU-CP806 and the target DU 804, the target DU 804 sends an F1: Setup Request (812) to CU-CP806 that includes TA information for all beams / beam groups for each cell of the target DU 804. The target DU 804 is shown in FIG. 8a as having a plurality of cells including Cell1, Cell2, etc., but the target DU 804 can include a single cell or can include two or more cells. In response to receiving the F1: Setup Request from the target DU 804, CU-CP806 sends an F1: Setup Response to the target DU 804 (814).

[0111] Figures 7a, 7b, and 8a show that the F1 communication interface can be set up (704, 724) between the target DU804 and the CU-CP806 before it is set up (702, 722) between the serving DU802 and the CU-CP806. However, the F1 communication interface can be set up (704, 724) between the target DU804 and the CU-CP806 before it is set up (702, 722) between the serving DU802 and the CU-CP806.

[0112] In some embodiments, as shown in Figure 8a, the CU-CP806 can provide TA information received from one DU to each of the other DUs of the base station. Thus, each DU can recognize the TA of the cells of the other DUs and thus can recognize whether RACH-less HO is possible for the cells of the other DUs. As shown in Figure 8a, the CU-CP806 can transmit (816) TA information about one or more cells of the second DU (also referred to herein as "adjacent DU") 804 to the first DU802, for example, in a gNB-CU configuration update message, and can transmit (818) TA information about one or more cells of the first DU802 to the second DU804, for example, in a gNB-CU configuration update message. Figure 8a shows that the CU-CP transmits (816) the TA information to the first DU802 before transmitting (818) the TA information to the second DU804. However, the TA information can be transmitted (818) to the second DU804 before the TA information is transmitted (816) to the first DU802.

[0113] In one embodiment, after an F1 communication interface is set up (702, 704) between the CU-CP 806 and each of the first and second DUs 802, 804, the CU-CP 806 can select a configuration of at least one target cell for LTM using data received from at least one of the DUs 802, 804. The data can also be received before the CU-CP 806 receives a notification (708) from the serving DU 802 that a service change is required for the UE. Only a handover (HO) from one cell of a DU of the base station to another cell of another DU of the base station is performed, and the CU-CP 806 receives a notification that such a change is required. Thus, by receiving data related to the HO before the CU-CP 806 receives the notification (708) from the serving DU 802, it can be ensured that the CU-CP 806 has data related to the HO in hand before the need for the HO arises.

[0114] In some embodiments, such as those illustrated in FIGS. 7c and 8b, where the CU-CP 806 receives data related to the HO after F1 setup and before the CU-CP 806 receives a notification (708) that a serving cell change is required for the UE, the CU-CP 806 can determine the likelihood of dynamic switching using a machine learning (ML)-based data collection and training algorithm. Machine learning can include artificial intelligence (AI), as would be understood by those skilled in the art. The CU-CP 806 can receive data related to the HO periodically before the CU-CP 806 receives a notification (708) that a serving cell change is required for the UE, and the CU-CP can use machine learning to build an HO policy based at least in part on the received data. The CU-CP 806 can also provide a policy to the DUs 802, 804 of the base station such that the DUs 802, 804 recognize how at least one target cell should be prepared for LTM before the at least one target cell needs to be prepared for LTM.

[0115] Data that the CU-CP806 can collect from the DUs 802, 804 and use for construction may include data regarding the type of the UE, the speed of the UE, at least one service accessed by the UE in the serving DU 802, and at least one of the dynamic handovers between the first cell of the serving DU 802 and the second cell of the serving DU 802.

[0116] The UE type (and / or capability), speed, and accessed service may enable machine learning in the CU-CP806 to identify the type of UE that is undergoing a dynamic handover and generate different policies for different types of UEs. Having different policies for being different recognizes that different UEs may have different types of mobility. For example, a cellular phone (a first type of UE) typically has more mobility than a laptop (a second type of UE), and a laptop (a second type of UE) typically has more mobility than a parking meter (a third type of UE). In another example, a smartwatch (a fourth type of UE) typically has more mobility than a game console (a fifth type of UE), and a game console (a fifth type of UE) typically has more mobility than a server (a sixth type of UE). Examples of UEs include cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, Global Positioning System (GPS), multimedia devices, video devices, digital audio players (e.g., MP3 players, etc.), cameras, game consoles, tablets, smart devices, wearable devices (e.g., smartwatches or other devices), vehicles, electric meters, gas pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other similarly functioning device. The UE can be an Internet of Things (IoT) device (e.g., a parking meter, gas pump, toaster, vehicle, heart monitor, etc.).

[0117] Dynamic switching is a phenomenon where the network anticipates ping-pong between the serving cell and the target cell and prepares the serving cell and the target cell to be equipped for this reciprocal switching. Associating dynamic switching with the type of UE can be used to optimize the network planning in the load cell. Data related to dynamic switching between the first cell of the serving DU802 and the second cell of the serving DU802 may include identification information of the first cell and the second cell, the frequency of switching occurrence including source beam information and target beam information, the time when the dynamic switching occurs, and / or important resources in the serving DU802 that become overloaded for the dynamic switching. Associating the source beam information and the target beam information with the type of UE can be used to optimize the network planning in the load cell. Knowing the time can enable an optimized resource plan in the cell receiving the dynamic switching. Knowing the overload of important resources can assist the optimized resource management from the CU-CP806.

[0118] As shown in FIGS. 7c and 8b, the first DU802 can periodically transmit (730, 820) to the CU-CP806 data related to HO including at least one of the type of the UE, the speed of the UE, at least one service accessed by the UE in the serving DU802, and at least one of dynamic handovers between the first cell of the serving DU802 and the second cell of the serving DU802. The second DU804 can also periodically transmit (732, 822) to the CU-CP806 data related to HO including at least one of the type of the UE, the speed of the UE, at least one service accessed by the UE in the second DU804, and at least one of dynamic handovers between the first cell of the second DU804 and the second cell of the second DU804. As also shown in FIGS. 7c and 8b, the data can be transmitted (730, 820) from the serving DU802 in a status report message via a previously set up (702) F1 interface, and can be transmitted (732, 822) from the target DU804 in a status report message via a previously set up (704) F1 interface. FIG. 8b shows that the first DU802 transmits (730, 820) data to the CU-CP806 before the second DU804 transmits (732, 832) data to the CU-CP806, but the second DU804 can transmit (732, 832) data to the CU-CP806 before the first DU802 transmits (730, 830) data to the CU-CP806.

[0119] The timing of the periodic reports from DU802, 804 can be pre-programmed and can be based on one or more factors. As an example of a factor, the periodic report can be sent according to a predetermined time schedule so that the report is periodically received by CU-CP806. As another example of a factor, the periodic report can be sent after a predetermined number of serving cell changes have occurred within the DU (e.g., a predetermined number of handovers have occurred). As yet another example of a factor, the periodic report can be sent based on the size of the report. Since the DU typically serves multiple UEs and data is sent to CU-CP806 for each UE, the report can grow large.

[0120] CU-CP806 uses an ML-based data collection and training algorithm to generate and construct a handover policy (824) at least partially based on the data received from DU802, 804 in the status report. CU-CP806 can be configured to repeatedly generate and construct the policy (824) when new data is received. The ML-based data collection and training algorithm is specific to RRM and is thus vendor-specific. In other words, the vendor of CU-CP806, e.g., the vendor of the gNB including CU-CP806, can manage resources and construct its own algorithm to configure the UE as desired for that particular vendor.

[0121] The CU-CP806 notifies (736) the first and second DUs 802, 804 of the handover policy including its parameters and values. As shown in FIG. 8b, the notification (736) may include the CU-CP806 transmitting (826) a gNB-CU configuration policy message to the first DU 802 via a previously set up (702) F1 communication interface, and transmitting (828) a gNB-CU configuration policy message to the second DU 804 via a previously set up (704) F1 communication interface. FIG. 8b shows the CU-CP806 transmitting (826) the handover policy to the first DU 802 before transmitting (828) the handover policy to the second DU 804, but the CU-CP806 can transmit (826) the handover policy to the first DU 802 after transmitting (828) the handover policy to the second DU 804.

[0122] As shown in FIG. 8b, after notifying (736) the first and second DUs 802, 804 of the handover policy, the CU-CP806 can fine-tune (834) the ML-based data collection and training algorithm using the performance feedback transmitted (830) from the first DU 802 to the CU-CP806 and the performance feedback transmitted (832) from the second DU 804 to the CU-CP806. Thus, the algorithm can become more effective over time. The performance feedback can be transmitted (830, 832) any number of times, and thus the fine-tuning (834) can be repeated any number of times.

[0123] In some embodiments, such as the embodiments illustrated in FIGS. 7d and 8c, where the CU-CP806 receives HO-related data after the F1 setup and before receiving a notification (708) that a serving cell change is required for the UE, the HO-related data received by the CU-CP806 includes the resource availability of one or more cells of the DU. The resource availability includes the availability in each of one or more cells for one or more of ICBM, dynamic switching, mTRP, and LTM SCC. In some embodiments, the availability for each of ICBM, dynamic switching, mTRP, and LTM SCC is provided to the CU-CP806, whereby the CU-CP806 has as much information as possible about the resources available in the cell / beam group and may be able to make an information-based configuration decision for the target cell.

[0124] As shown in FIGS. 7d and 8c, the first DU802 can periodically transmit (738, 836) HO-related data including the resource availability of one or more cells of the first DU. The second DU804 can also periodically transmit (740, 838) HO-related data including the resource availability of one or more cells of the second DU to the CU-CP806. FIG. 8c shows that the first DU802 transmits (738, 836) data to the CU-CP806 before the second DU804 transmits (740, 838) data to the CU-CP806, but the second DU804 can transmit (740, 838) data to the CU-CP806 before the first DU802 transmits (738, 836) data to the CU-CP806. The periodic reporting of resource availability reflects that the resources can become available or unavailable based on one or more new UEs served by a particular DU, a particular DU that has stopped serving one or more UEs, and / or a change in the needs of one or more UEs served by a particular DU.

[0125] The timing of the periodic reports from DU802, 804 can be pre-programmed and can be based on one or more factors. As an example of a factor, the periodic report can be sent according to a predetermined time schedule so that the report is periodically received by CU-CP806. As another example of a factor, the periodic report can be sent after a predetermined number of serving cell changes occur in the DU (e.g., a predetermined number of dynamic handovers occur). As yet another example of a factor, the periodic report can be sent based on the size of the report. Since the DU typically serves multiple UEs and data is sent to CU-CP806 for each UE, the report can grow large.

[0126] In some embodiments, such as those illustrated in FIGS. 7e and 8d, where the CU-CP806 receives HO-related data after F1 setup and before receiving a notification (708) from the UE that a serving cell change is required, the HO-related data received by the CU-CP806 includes timing advance information for one or more beams or beam groups of the DU. The timing advance information can be the average timing advance value used by the UE within each beam or beam group for a given reference signal received power (RSRP) value or RSRP range. Thus, the data provided to the CU-CP806 can also include the RSRP value or range and the beam or beam group associated with a given average TA value. The CU-CP806 can use the received average TA information to determine the feasibility of ICBM in the target DU cell. The DU that provides the average TA value can be configured to calculate the average TA so as to have such information available for providing to the CU-CP806.

[0127] As shown in FIGS. 7e and 8d, the CU-CP806 can send requests (742, 850) to the first DU802 for data related to HO including average TA, RSRP, and beam or beam group. In response to receiving the request from the CU-CP806, the first DU802 sends a response (852) approving the request to the CU-CP806 and sends (854) the requested data related to HO including average TA, RSRP, and beam or beam group to the CU-CP806. As shown in FIG. 8d, the request can be an F1 resource status request message, the response positive response can be an F1 resource status response message, and the requested data can be sent (854) in an F1 resource status update message. The CU-CP806 can also send requests (744, 856) to the second DU804 for data related to HO including average TA, RSRP, and beam or beam group. In response to receiving the request from the CU-CP806, the second DU804 sends a response (858) approving the request to the CU-CP806 and sends (860) the requested data related to HO including average TA, RSRP, and beam or beam group to the CU-CP806. As shown in FIG. 8d, the request can be an F1 resource status request message, the response positive response can be an F1 resource status response message, and the requested data can be sent (860) in an F1 resource status update message. FIG. 8d shows the CU-CP806 requesting data from the first DU802 before the second DU804, but the CU-CP806 can request data from the second DU804 before the first DU802. Also, FIG. 8d shows the first and second DUs 802, 804 each sending the average TA, RSRP, and beam or beam group to the CU-CP806 in an F1 resource status update message via the previously set up (702, 704) F1 communication interface.However, each of the first and second DU802, 804 can send the average TA, RSRP, and beam or beam group to the CU-CP806 in another non-UE-related message such as a gNB-DU configuration update message. Further, the transmitted (742, 744, 854, 860) RSRP values can be classified into a small range to reduce implementation complexity.

[0128] The average TA, RSRP, and beam or beam group can be transmitted (742, 744, 854, 860) periodically from the DU to the CU-CP806. Alternatively, the CU-CP806 can request (850) the average TA, RSRP, and beam or beam group information from the serving DU802 whenever the DU-to-DU LTM target cell is ready.

[0129] In one embodiment, as shown in FIG. 8d, the CU-CP 806 can provide the RSRP, beam or beam group received from one DU, and the average TA information to each of the other DUs of the base station. Each DU can thus recognize the average TA of the beam / beam group of the other DUs, and thus recognize whether ICBM is feasible, for example, whether ICBM can be configured for a UE within a given target cell. The UE that provides the RSRP for the target cell having a given timing advance value in the serving cell can determine whether ICBM is feasible in the target DU cell by comparing with the information received from the target DU 804. As shown in FIG. 8d, the CU-CP 806 can transmit (862) the RSRP, beam or beam group, and the average TA information for one or more beams or beam groups of the second DU 804 to the first DU 802, for example, in an F1 gNB-CU configuration update message, and can transmit (864) the RSRP, beam or beam group, and the average TA information for one or more beams or beam groups of the first DU 802 to the second DU 804, for example, in an F1 gNB-CU configuration update message. FIG. 8d shows that the CU-CP transmits (862) the average TA information to the first DU 802 before transmitting (864) the average TA information to the second DU 804, but the average TA information can be transmitted (864) to the second DU 804 before the average TA information is transmitted (862) to the first DU 802.

[0130] Referring again to FIG. 7a, in response to receiving a request from the CU-CP 808, for example, in response to receiving a UE context setup request message from the CU-CP 808, the target DU 804 prepares (712) each of at least one target cell for LTM. In this illustrated embodiment, the at least one target cell includes only the target DU 804 that prepares one target cell.

[0131] The target DU804 notifies the CU-CP806 that the preparation is complete. The notification to the CU-CP806 may include the target DU804 sending a UE context setup response message to the CU-CP806 in accordance with the 3GPP standard using the previously set up (704) F1 communication interface.

[0132] In one embodiment, the target DU804 being requested by the CU-CP806 to prepare at least one target cell may include the CU-CP806 sending an indication of a target cell configuration that is at least one of ICBM, dynamic switching, and LTM SCC. Since the CU-CP806 has previously received at least one resource availability report from a second DU804, for example, as described above with respect to FIGS. 7d and 8c, the CU-CP806 may be able to indicate the target cell configuration as at least one of ICBM, dynamic switching, and LTM SCC, and the second DU804, such as the last received resource availability report, is known by the CU-CP806 to have one or more of the indicated available ICBM, dynamic switching, and LTM SCC, so the likelihood of success is higher than in the case where there is no such resource availability report.

[0133] FIG. 8c shows an embodiment in which the request to the second DU804 includes the CU-CP806 indicating the target cell configuration to the second DU804. As shown in FIG. 8c, the target cell configuration can be sent (846) to the second DU804 in a UE context setup request message. FIG. 8c also shows the second DU804 sending (848) a UE context setup response message to the CU-CP806.

[0134] Referring back to FIG. 7a, CU-CP 806 identifies each of the target cells that can handle one or more LTMs and notifies the serving DU 804 of at least one target cell that can handle an LTM by including information regarding each of the one or more target DUs (714). In an inter-DU LTM scenario, one or more of the target cells that can handle at least one LTM belong to a DU different from the serving DU 802. For example, referring to the system of FIG. 6b, the serving DU can be the small cell 626 of macro1 DU 628a, and one or more of the target cells can be one or more small cells 626 of macro2 DU 628b and / or macro3 DU 628c.

[0135] The notification (714) to the serving DU 802 may include the CU-CP 806 transmitting a UE context change request message to the serving DU 802 using the previously set up (702) F1 communication interface. The UE context change request message can include, for each of the one or more target DUs, cell identification information (e.g., a unique cell ID that identifies the target DU such as a physical cell identifier (PCI)) or an index corresponding to the cell ID.

[0136] In response to being notified (714) of at least one target DU cell that can handle an LTM, serving DU 802 stores the received information regarding the at least one LTM target cell, for example, stores a list of target cells that can handle the LTM. Also, in response to being notified (714) of at least one target DU 804, serving DU 802 can send a UE context change response message to CU-CP 806 using a previously set up (702) F1 communication interface. The UE context change response message may include integrated cell group configuration information for each one or more target cells identified by CU-CP 806 for the UE. The UE context change request message and the UE context change response message are each defined by 3GPP. Thus, serving DU 802 can receive information regarding at least one target cell from CU-CP 806 and can approve that reception to CU-CP 806 using a message already sent for HO according to 3GPP specifications.

[0137] In one embodiment, the notification (714) to serving DU 802 may include CU-CP 806 indicating a target cell configuration to serving DU 802. As described above, the indication of the target cell configuration can be at least one of ICBM, dynamic switching, and LTM SCC. For example, the indicated target cell configuration can be ICBM. In another example, the indicated target cell configuration can be dynamic switching. In yet another example, the indicated target cell configuration can be LTM SCC. In yet another example, the indicated target cell configuration can be ICBM and dynamic switching. In another example, the indicated target cell configuration can be LLM SCC and dynamic switching.

[0138] Figure 8c shows an embodiment in which the notification (714) to serving DU802 includes the CU-CP806 indicating the target cell configuration to serving DU802. As shown in Figure 8c, the target cell configuration can be sent (842) to serving DU802 in a UE context change request message. Figure 8c also shows serving DU802 sending a UE context change response message to CU-CP806 (842).

[0139] Referring again to Figure 7a, in response to receiving the UE context change response message, CU-CP806 can send an RRC reconfiguration message to the UE according to 3GPP specifications. The RRC reconfiguration message includes, for example, LTM target cell configuration information such as that provided from target DU804 to CU-CP806 in the sent UE context setup response message.

[0140] In response to receiving the target cell configuration in the RRC reconfiguration message, the UE can send an L1 measurement report to serving DU802 according to 3GPP specifications. The L1 measurement report provides the UE measurement radio state information of the configured target cell to serving DU802.

[0141] In response to receiving the L1 measurement report sent from the UE, serving cell 802 selects (716) a target cell from among the one or more target cells capable of handling the identified LTMs for serving DU802. In this illustrated embodiment, since there is only one target cell (target DU804) identified for serving DU802 as a target cell capable of handling the LTM by CU-CP806, the selection of the serving cell (716) is straightforward and serving DU802 selects target DU806 (716). If there are multiple target cells capable of handling the LTM that meet the handover criteria in serving DU802, serving DU802 can select a target cell in any of a variety of ways including selection by conventional procedures according to 3GPP.

[0142] In an embodiment where there are a plurality of target cells identified for the serving DU802 by the CU-CP806, the serving cell target cell selection (716) may include determining which one or more of the plurality of target cells have a radio quality that exceeds a predetermined threshold radio quality. The predetermined threshold radio quality is defined by the radio state of the UE received by the serving DU802 in the L1 measurement report from the UE. Thus, the serving DU802 can take into account the specific needs of a particular UE involved in the HO when selecting (716) the target cell for the HO. Further, the L1 measurement report transmitted by the UE to the serving DU802 may report L1 measurement values including the reference signal received power (RSRP) defined by 3GPP for each of the plurality of target cells, and the identification information thereof is known to the UE as provided by the CU-CP806 to the UE in the RRC reconfiguration message. Thus, the serving DU802 can analyze the L1 measurement report received from the UE to determine which one or more of the plurality of target cells have a radio quality that exceeds a predetermined threshold radio quality.

[0143] If only one of the plurality of target cells meets the radio state of the UE, for example, if only one of the radio qualities of the target cells exceeds a predetermined threshold radio quality, the serving cell 802 selects (716) that target cell. If two or more of the plurality of target cells meet the radio state of the UE, for example, if the radio qualities of the target cells each exceed a predetermined threshold radio quality, any one of these target cells can meet the needs of the UE, and one of these target cells can be selected randomly or according to another desired criterion.

[0144] When a target cell (e.g., target DU804 in the illustrated embodiment of FIG. 8a) is selected (716), the serving DU802 triggers (718) a serving cell change to the selected (716) target cell. Triggering a serving cell change (718) may include the serving DU802 including a serving cell change command and transmitting to the UE a MAC CE that identifies the selected (716) target cell to the UE, e.g., by PCI or other identifier.

[0145] The reception of the UE's MAC CE indicates to the UE that an LTM serving cell change (SCC) must be performed for the identified target cell, e.g., target DU804 in the illustrated embodiments of FIGS. 8a - 8d for the UE. Thus, in response to receiving the MAC CE from the serving cell 802, the UE initiates (720) an HO to the target cell. The HO can be performed in accordance with 3GPP specifications. In response to the UE accessing the target cell, the target DU804 can transmit a serving cell change notification that identifies the target DU804, e.g., by a unique identifier per 3GPP, as the new current serving cell for the UE for at least one service, via the previously set up (704) F1 communication interface to the CU - CP806. Also, in response to receiving the MAC CE from the serving cell 802, the UE can transmit an RRC reconfiguration positive acknowledgement message to the CU - CP806. Thus, the CU - CP806 receives an affirmative response from both the UE via an RRC reconfiguration positive acknowledgement message indicating a normal RRC reconfiguration in the UE and from the target DU804 via a serving cell change notification that the target DU804 is currently serving the UE for at least one service that has been handed over from the serving DU802.

[0146] In some embodiments, such as the various embodiments described above in connection with FIGS. 7a-8d, the CU-CP receives from the DU data related to HO of at least one service for the UE. In other embodiments, the DU of the base station can directly share their TA information with each other such that the first DU receives from at least one other DU data related to HO of at least one service for the UE. Such DU-to-DU communication is not possible in a 5G wireless communication system but may be possible in a 6G or later wireless communication system. In embodiments where the first DU receives data from at least one other DU, the first DU operates in the same manner as described above with respect to the CU-CP 806 of FIGS. 7a-8d and can request one or more of the at least one other DUs to prepare at least one LTM target cell for HO of at least one service for the UE, taking the data into consideration.

[0147] Using the embodiments of FIGS. 7b and 8a as examples of embodiments where DU-to-DU communication is possible, instead of the first DU 802 transmitting the TA information of all beams / beam groups for each cell of the first DU 802 to the CU-CP 806, the first DU 802 transmits the TA information to the second DU 804, and instead of the second DU 804 transmitting the TA information of all beams / beam groups for each cell of the second DU 804 to the CU-CP 806, the first DU 802 transmits the TA information to the first DU 802. Further, instead of the CU-CP 806 selecting a configuration and requesting the second DU 804 to prepare at least one target cell according to the selected configuration, the first DU 802 performs such selection and request. The inter-DU transmission of TA information does not occur during the setup of the F1 communication interface since, as described above, the F1 communication interface is for CU-DU communication. Instead, the inter-DU transmission of TA information can be performed according to the specifications related to the wireless communication system in which the first and second DUs 802, 804 are configured to communicate with each other as appropriate during the setup of the communication interface between the first DU 802 and the second DU 804.

[0148] Figure 9 shows an exemplary architecture of a DU900 that can be used as an architecture for the DU802 and 804 of FIGS. 8a-8d. As shown in FIG. 9, the DU900 includes a memory 902, a processor 904, a communication unit 906, and a configuration management controller 908. The communication unit 906 is configured to communicate internally between the internal hardware components of the DU900 and with external devices via one or more networks. The communication unit 906 may include electronic circuits specific to the standards that enable wired or wireless communication. The configuration management controller 908 is configured to perform the configuration selection described above, and the memory 900 is configured to store the configuration therein. Multiple configurations can be stored in the memory 900 in one configuration per UE so that the DU900 maintains configurations for multiple UEs. Although FIG. 9 shows the hardware components of the DU900, other embodiments of the DU900 are possible. For example, the DU900 may include fewer or more components. One or more components can be combined together to perform the same or substantially similar technical features for latency management.

[0149] In one embodiment, the subject matter can be configured to be implemented in a system 1000, as shown in FIG. 10. The system 1000 can include one or more of a processor 1010, a memory 1020, a storage device 1030, and an input / output device 1040. Each of the components 1010, 1020, 1030, and 1040 can be interconnected using a system bus 1050. The processor 1010 can be configured to process instructions for execution within the system 600. In one embodiment, the processor 1010 can be a single-threaded processor. In an alternative embodiment, the processor 1010 can be a multi-threaded processor. The processor 1010 can be further configured to process instructions stored in the memory 1020 or the storage device 1030, which can include receiving or sending information through the input / output device 1040. The memory 1020 can store information within the system 1000. In one embodiment, the memory 1020 can be a computer-readable medium. In an alternative embodiment, the memory 1020 can be a volatile memory unit. In yet another embodiment, the memory 1020 can be a non-volatile memory unit. The storage device 1030 can be capable of providing mass storage for the system 1000. In one embodiment, the storage device 1030 can be a computer-readable medium. In an alternative embodiment, the storage device 1030 can be a floppy disk device, a hard disk device, an optical disk device, a tape device, a non-volatile solid state memory, or any other type of storage device. The input / output device 1040 can be configured to provide input / output operations for the system 1000. In one embodiment, the input / output device 1040 can include a keyboard and / or a pointing device. In an alternative embodiment, the input / output device 1040 can include a display unit for displaying a graphical user interface.

[0150] FIG. 11 shows an exemplary method 1100 for configuration selection extension for LTM according to an embodiment of the present subject matter. The method 1100 can be executed using, for example, the embodiments shown in FIGS. 6a - 9 and described with respect to FIGS. 6a - 9.

[0151] The method 1100 includes receiving (1102) at a CU - CP of a base station, data related to preparing an LTM HO configuration for at least one service for a UE from a first DU of the base station. The method also includes, after receiving the data, requesting (1104) at the CU - CP from a second DU of the base station to prepare at least one LTM target cell configuration for HO of at least one service for the UE in consideration of the data.

[0152] In an embodiment, the present subject matter can include one or more of the following optional features.

[0153] In an embodiment, the data can include timing advance information for each of a plurality of cells of the DU. Further, the CU - CP can receive the data in a procedure of setting up an F1 communication interface between the CU - CP and the first DU, and / or the CU - CP can receive the data in an F1 setup request message transmitted from the first DU to the CU - CP, or the timing advance information can include average timing advance information of given reference signal received power (RSRP) values for each of a plurality of beams or beam groups of a plurality of cells of the second DU, and the CU - CP can receive the average timing advance information from the first DU before the CU - CP receives a message from the first DU that a service change for the UE is required, and / or the CU - CP can receive the data periodically in a non - UE - related procedure between the CU - CP and the second DU.

[0154] In one embodiment, receiving (1102) may include the CU-CP periodically receiving data from the first DU before receiving from the first DU a message that a service change for the UE is required, and the method may further include, at the CU-CP, constructing a HO policy using machine learning, at least partially based on the received data. Further, the data may include data regarding at least one of a type of the UE, a speed of the UE, at least one service accessed by the UE in the first DU, and dynamic switching between a first cell and a second cell, and / or the method may further include, at the CU-CP, receiving performance data regarding the service of the first DU to the UE from the first DU that is currently serving the UE for at least one service, and requesting may include requesting the second DU to prepare at least one LTM target cell, considering also the data received from the first DU.

[0155] In one embodiment, the first DU may include at least one cell, the data may include resource availability of at least one cell, receiving may include the CU-CP periodically receiving resource availability from the first DU before receiving from the first DU a message that a service change for the UE is required for at least one service, and / or the resource availability may include availability in each of at least one cell for inter-cell beam management (ICBM), dynamic switching, multi-transmit receive point (mTRP), and LTM serving cell change (SCC).

[0156] In one embodiment, requesting (1102) may include transmitting, from the CU-CP to the second DU, an indication of a target cell configuration that is at least one of ICBM, dynamic switching, and LTM SCC.

[0157] In one embodiment, before the CU-CP receives from a first DU that is currently providing service to the UE a message that service change is required for the UE for at least one service, the CU-CP can receive data from the first DU.

[0158] In one embodiment, the method 1100 may also include, at the CU-CP, selecting a target cell configuration based at least in part on the received data.

[0159] In one embodiment, the base station may have a non-agglomerated architecture.

[0160] In one embodiment, the base station may include an NG-RAN node including a gNodeB or an ng-eNodeB.

[0161] In one embodiment, the base station may include at least one processor and may also include at least one non-transitory storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to execute the method 1100.

[0162] The systems and methods disclosed herein can be embodied in a variety of forms, including, for example, a data processor such as a computer, which also includes databases, digital electronic circuits, firmware, software, or combinations thereof. Further, the above features, as well as other aspects and principles of the embodiments of the present disclosure, can be implemented in a variety of environments. Such environments and related applications can be specially constructed to execute various processes and operations in accordance with the disclosed embodiments, or they can include a general-purpose computer or computing platform that is selectively activated or reconfigured by code to provide the necessary functionality. The processes disclosed herein are essentially independent of any particular computer, network, architecture, environment, or other device, and can be implemented by a suitable combination of hardware, software, and / or firmware. For example, various general-purpose machines can be used with programs written in accordance with the teachings of the disclosed embodiments, or it may be more convenient to construct a dedicated device or system for performing the required methods and techniques.

[0163] The systems and methods disclosed herein can be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, such as a machine-readable storage device or a propagated signal, for execution by, or to control the operation of, a data processing apparatus, such as a programmable processor, a computer, or multiple computers. The computer program can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. The computer program can be deployed to be executed on one computer or on multiple computers distributed at one site or across multiple sites and interconnected by a communication network.

[0164] As used herein, the term "user" can refer to any entity, including a person or a computer.

[0165] Ordinal numbers such as first, second, etc. may be related to order in some situations, but as used in this document, ordinal numbers do not necessarily imply order. For example, ordinal numbers can be used simply to distinguish one item from another. For example, distinguishing a first event from a second event need not imply any chronological order or fixed reference system (such that the first event within one paragraph of the description may be different from the first event within another paragraph of the description).

[0166] The foregoing description is intended to illustrate, not to limit, the scope of the invention as defined by the appended claims. Other embodiments are within the scope of the following claims.

[0167] These computer programs, which may also be referred to as programs, software, software applications, applications, components, or code, include machine instructions for a programmable processor and can be implemented in high-level procedural and / or object-oriented programming languages and / or in assembly / machine language. As used herein, the term "machine-readable medium" refers to any computer program product, apparatus, and / or device used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives the machine instructions as a machine-readable signal, such as, for example, magnetic disks, optical disks, memory, and programmable logic devices (PLDs). The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor. A machine-readable medium can store such machine instructions non-transitorily, such as, for example, a non-transitory solid state memory or a magnetic hard drive or any equivalent storage medium. A machine-readable medium can alternatively or additionally store such machine instructions temporarily, such as, for example, a processor cache or other random access memory associated with one or more physical processor cores.

[0168] To provide for interaction with a user, the subject matter described herein can be implemented on a computer having, for example, a display device such as a cathode ray tube (CRT) or a liquid crystal display (LCD) monitor for displaying information to the user and a keyboard and a pointing device such as a mouse or a trackball by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well. For example, feedback provided to the user can be any form of sensory feedback, such as, for example, visual feedback, auditory feedback, or tactile feedback, and input received from the user can be received in any form, including, but not limited to, acoustic, speech, or tactile input.

[0169] The subject matter described in this specification can be implemented in a computing system that includes backend components such as, for example, one or more data servers, or includes middleware components such as, for example, one or more application servers, or includes frontend components such as, for example, one or more client computers having a graphical user interface or a web browser through which a user can interact with embodiments of the subject matter described in this specification, or in any combination of such backend, middleware, or frontend components. The components of the system can be interconnected by any form or medium of digital data communication such as, for example, a communication network. Examples of communication networks include, but are not limited to, local area networks ("LANs"), wide area networks ("WANs"), and the Internet.

[0170] A computing system can include clients and servers. Clients and servers are generally, but not exclusively, separate from each other and typically interact via a communication network. The relationship between a client and a server arises by computer programs that operate on respective computers and have a client-server relationship to each other.

[0171] The embodiments described in the foregoing description do not represent all embodiments that are consistent with the subject matter described herein. Rather, they are only some examples that are consistent with aspects related to the subject matter being described. Although certain variations have been described in detail above, other modifications or additions are possible. In particular, in addition to what has been described herein, further features and / or variations can be provided. For example, the above-described embodiments can be directed to various combinations and sub-combinations of the disclosed features, and / or combinations and sub-combinations of certain further features disclosed above. Additionally, the logical flows shown in the accompanying figures and / or described herein do not necessarily require the specific order, or sequential order, shown to achieve the desired result. Other embodiments may be within the scope of the following claims.

Claims

1. at least one processor; and at least one non-transitory memory medium storing instructions that, when executed by the at least one processor, cause the at least one processor to receive, in a central unit control plane (CU-CP) of a base station, data related to preparing a layer 1 / layer 2 trigger mobility (LTM) handover (HO) configuration for at least one service for a user equipment (UE) from a first distributed unit (DU) of the base station; and after receiving the data, request, by the CU-CP, a second DU of the base station to prepare at least one LTM target cell configuration for HO of the at least one service for the UE in consideration of the data to perform an operation including a device.

2. The device according to claim 1, wherein the data includes timing advance information for each of a plurality of cells of the second DU.

3. The device according to claim 2, wherein the CU-CP receives the data in a procedure of setting up an F1 communication interface between the CU-CP and the first DU.

4. The device according to claim 3, wherein the CU-CP receives the data in an F1 setup request message transmitted from the first DU to the CU-CP.

5. The timing advance information includes average timing advance information of given reference signal received power (RSRP) values for each of a plurality of beams or beam groups of the plurality of cells of the second DU, and the CU-CP receives the average timing advance information from the first DU before the CU-CP receives a message from the first DU that a service change for the UE is required.

6. The device according to claim 5, wherein the CU-CP receives the data periodically in a non-UE related procedure between the CU-CP and the first DU.

7. The receiving includes the CU-CP receiving the data periodically from the first DU before the CU-CP receives a message from the first DU that a service change for the UE is required, ​ The apparatus according to claim 1, wherein the operation further includes, in the CU-CP, constructing an HO policy using machine learning based at least in part on the received data.

8. The data includes the type of the UE, the speed of the UE, at least one service accessed by the UE in the first DU, and dynamic switching between a first cell and a second cell The apparatus according to claim 7, including data regarding at least one of them.

9. The operation further includes, in the CU-CP, receiving performance data regarding the service of the first DU to the UE from the first DU that is currently providing service to the UE for the at least one service, The apparatus according to claim 7, wherein the requesting requests the second DU to prepare the at least one LTM target cell in consideration of the data received from the first DU.

10. The first DU includes at least one cell, The data includes the resource availability of the at least one cell, The receiving includes the CU-CP periodically receiving the resource availability from the first DU before the CU-CP receives, from the first DU that is currently providing service to the UE for the at least one service, a message indicating that a service change is required for the UE. The apparatus according to claim 1.

11. The apparatus according to claim 10, wherein the resource availability includes availability in each of the at least one cell for inter-cell beam management (ICBM), LTM serving cell change (SCC) with dynamic switching, multi-transmission and reception point (mTRP), and LTM SCC.

12. The apparatus according to claim 1, wherein the requesting includes transmitting, from the CU-CP to the second DU, an instruction for target cell configuration that is at least one of inter-cell beam management (ICBM), LTM serving cell change (SCC) with dynamic switching, and LTM SCC.

13. The apparatus according to claim 1, wherein the CU-CP receives data from the first DU before receiving from the first DU a message to the UE that a service change is required for at least one of the at least one service currently provided to the UE.

14. The apparatus according to claim 1, wherein the operation further comprises, at the CU-CP, selecting a target cell configuration based at least in part on the received data.

15. The apparatus according to claim 1, wherein the base station has a non-agglomerated architecture.

16. The apparatus according to claim 1, wherein the base station includes a next-generation radio access network (NG-RAN) node including a gNodeB or an ng-eNodeB.

17. The apparatus according to claim 1, wherein the base station includes the at least one processor and the at least one non-transitory storage medium.

18. When executed by at least one processor, the at least one processor receives, at a central unit control plane (CU-CP) of a base station, data related to preparing a layer 1 / layer 2 trigger mobility (LTM) handover (HO) configuration for at least one service for a user equipment (UE) from a first distributed unit (DU) of the base station; and after receiving the data, requests, by the CU-CP, a second DU of the base station to prepare at least one LTM target cell configuration for the HO of the at least one service for the UE in consideration of the data. A non-transitory storage medium storing instructions that cause an operation including the above to be executed.

19. Receiving, at a central unit control plane (CU-CP) of a base station, data related to preparing a layer 1 / layer 2 trigger mobility (LTM) handover (HO) configuration for at least one service for a user equipment (UE) from a first distributed unit (DU) of the base station; and after receiving the data, requesting, by the CU-CP, a second DU of the base station to prepare at least one LTM target cell configuration for the HO of the at least one service for the UE in consideration of the data. A computer-implemented method including the above.

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