WO2025199856A1

WO2025199856A1 - Configuration and ue methods for implementing inter-cu l1/l2 triggered mobility (ltm)

Info

Publication number: WO2025199856A1
Application number: PCT/CN2024/084355
Authority: WO
Inventors: Fangli Xu; Naveen Kumar R Palle VENKATA; Ping-Heng Kuo; Zhibin Wu; Yuqin Chen; Haijing Hu; Ralf ROSSBACH; Alexander Sirotkin; Peng Cheng
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2024-03-28
Filing date: 2024-03-28
Publication date: 2025-10-02
Anticipated expiration: 2026-09-28

Abstract

An apparatus of a next generation Node B (gNB) comprising one or more processors coupled to a memory and configured to determine, at a source centralized unit (CU) of the gNB, candidate CUs for a user equipment (UE). The processors send a handover request from the source CU to the candidate CUs. The processors receive handover request acknowledgements from the candidate CUs at the source CU with information regarding candidate distributed units (DUs) coupled to the candidate CUs, to form a list of candidate DUs. The processors assign, at the source CU, indices for the candidate DUs coupled to the candidate CUs. The processors encode, at the source CU, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU.

Description

CONFIGURATION AND UE METHODS FOR IMPLEMENTING INTER-CU L1/L2 TRIGGERED MOBILITY (LTM)

FIELD

Embodiments of the invention relate to wireless communications, including apparatuses, systems, and methods for implementing inter-centralized unit (CU) Layer 1/Layer 2 Triggered Mobility (LTM) .

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. In recent years, wireless devices such as smart phones and tablet computers have become increasingly sophisticated. In addition to supporting telephone calls, many mobile devices now provide access to the internet, email, text messaging, and navigation using the global positioning system (GPS) and are capable of operating sophisticated applications that utilize these functionalities.

Long Term Evolution (LTE) has been the technology of choice for the majority of wireless network operators worldwide, providing mobile broadband data and high-speed Internet access to their subscriber base. LTE was first proposed in 2004 and was first standardized in 2008. Since then, as usage of wireless communication systems has expanded exponentially, demand has risen for wireless network operators to support a higher capacity for a higher density of mobile broadband users. In 2015, a study of a new radio access technology began and, in 2017, a first release of Fifth Generation New Radio (5G NR) was standardized.

5G-NR, also simply referred to as NR, provides, as compared to LTE, a higher capacity for a higher density of mobile broadband users, while also supporting device-to-device, ultra-reliable, and massive machine type communications with lower latency and/or lower battery consumption. Further, NR may allow for more flexible UE scheduling as compared to current LTE. Consequently, efforts are being made in ongoing developments of 5G-NR to take advantage of higher throughputs possible at higher frequencies.

SUMMARY

Embodiments relate to wireless communications, and more particularly to apparatuses, systems, and methods for an apparatus of a next generation Node B (gNB) , the apparatus comprising one or more processors, coupled to a memory. The processors are configured to determine, at a source centralized unit (CU) of the gNB, one or more candidate CUs for a user equipment (UE) . The processors are configured to send a handover request from the source CU of the gNB to the one or more candidate CUs. The processors are configured to receive handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB with information regarding candidate distributed units (DUs) coupled to each of the one or more candidate CUs, to form a list of candidate DUs. The processors are configured to assign, at the source CU of the gNB, indices for the candidate DUs coupled to the one or more candidate CUs. The processors are configured to encode, at the source CU of the gNB, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU of the gNB.

Other embodiments relate to a method for inter-central unit (CU) Layer1/Layer2-triggered mobility (LTM) at a next generation Node B (gNB) . The method comprises determining, at a source CU of the gNB, one or more candidate CUs for a user equipment (UE) . The method comprises sending a handover request from the source CU of the gNB to the one or more candidate CUs. The method comprises receiving handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB with information regarding candidate distributed units (DUs) coupled to the one or more candidate CUs, to form a list of candidate DUs. The method comprises assigning, at the source CU of the gNB, indices for the candidate DUs coupled to the one or more candidate CUs. The method comprises encoding, at the source CU of the gNB, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU of the gNB.

The techniques described herein may be implemented in and/or used with a number of different types of devices, including but not limited to unmanned aerial vehicles (UAVs) , unmanned aerial controllers (UACs) , base stations, access points, cellular phones, tablet computers, wearable computing devices, portable media players, and any of various other computing devices.

This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtained when the following detailed description of various embodiments is considered in conjunction with the following drawings, in which:

FIG. 1A illustrates an example wireless communication system according to some embodiments.

FIG. 1B illustrates an example of a base station and an access point in communication with a user equipment (UE) device, according to some embodiments.

FIG. 2 illustrates an example block diagram of a base station, according to some embodiments.

FIG. 3 illustrates an example block diagram of a server according to some embodiments.

FIG. 4 illustrates an example block diagram of a UE according to some embodiments.

FIG. 5 illustrates an example block diagram of cellular communication circuitry, according to some embodiments.

FIG. 6 illustrates an example of a baseband processor architecture for a UE, according to some embodiments.

FIG. 7 illustrates an example block diagram of an interface of baseband circuitry according to some embodiments.

FIG. 8 illustrates an example of a control plane protocol stack in accordance with some embodiments.

FIG. 9 illustrates an example of a user plane protocol stack in accordance with some embodiments.

FIG. 10 illustrates example components of a core network in accordance with some embodiments.

FIG. 11 provides an example diagram of intra-CU and inter-CU LTM cell switching, according to some embodiments.

FIG. 12 provides an example diagram of intra-CU and inter-CU LTM cell switching, according to some embodiments.

FIG. 13 illustrates an example of signaling for inter-CU LTM switching, according to some embodiments.

FIG. 14 illustrates a flow chart of an example of a method for inter-central unit (CU) Layer1/Layer2-triggered mobility (LTM) , according to some embodiments.

FIG. 15 illustrates an example of signaling for inter-CU LTM switching, according to some embodiments.

FIG. 16 illustrates an example of a MAC CEs for sending information, according to some embodiments.

FIG. 17 illustrates an example of a MAC CEs for sending information, according to some embodiments.

FIG. 18 illustrates an example of signaling for inter-CU LTM switching, according to some embodiments.

FIG. 19 illustrates an example of a MAC CE for sending information, according to some embodiments.

FIG. 20 illustrates an example of ASN. 1 code used for the network to configure the SIB1, according to some embodiments.

FIG. 21 illustrates an example of a MAC CE for sending information, according to some embodiments.

FIG. 22 illustrates an example of LTM switches, according to some embodiments.

While the features described herein may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to be limiting to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION

Terms

The following is a glossary of terms used in this disclosure:

Memory Medium –Any of various types of non-transitory memory devices or storage devices. The term “memory medium” is intended to include an installation medium, e.g., a CD-ROM, floppy disks, or tape device; a computer system memory or random-access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media, e.g., a hard drive, or optical storage; registers, or other similar types of memory elements, etc. The memory medium may include other types of non-transitory memory as well or combinations thereof. In addition, the memory medium may be located in a first computer system in which the programs are executed, or may be located in a second different computer system which connects to the first computer system over a network, such as the Internet. In the latter instance, the second computer system may provide program instructions to the first computer for execution. The term “memory medium” may include two or more memory mediums which may reside in different locations, e.g., in different computer systems that are connected over a network. The memory medium may store program instructions (e.g., embodied as computer programs) that may be executed by one or more processors.

Carrier Medium –a memory medium as described above, as well as a physical transmission medium, such as a bus, network, and/or other physical transmission medium that conveys signals such as electrical, electromagnetic, or digital signals.

Programmable Hardware Element includes various hardware devices comprising multiple programmable function blocks connected via a programmable interconnect. Examples include FPGAs (Field Programmable Gate Arrays) , PLDs (Programmable Logic Devices) , FPOAs (Field Programmable Object Arrays) , and CPLDs (Complex PLDs) . The programmable function blocks may range from fine grained (combinatorial logic or look up tables) to coarse grained (arithmetic logic units or processor cores) . A programmable hardware element may also be referred to as "reconfigurable logic” .

Computer System (or Computer) –any of various types of computing or processing systems, including a personal computer system (PC) , mainframe computer system, workstation, network appliance, Internet appliance, personal digital assistant (PDA) , television system, grid computing system, or other device or combinations of devices. In general, the term "computer system" can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions from a memory medium.

User Equipment (UE) (or “UE Device” ) –any of various types of computer systems devices which are mobile or portable and which performs wireless communications. Examples of UE devices include mobile telephones or smart phones (e.g., iPhone^TM, Android^TM-based phones) , portable gaming devices (e.g., Nintendo DS^TM, PlayStation Portable^TM, Gameboy Advance^TM, iPhone^TM) , laptops, wearable devices (e.g., smart watch, smart glasses) , PDAs, portable Internet devices, music players, data storage devices, other handheld devices, unmanned aerial vehicles (UAVs) (e.g., drones) , UAV controllers (UACs) , and so forth. In general, the term “UE” or “UE device” can be broadly defined to encompass any electronic, computing, and/or telecommunications device (or combination of devices) which is easily transported by a user and capable of wireless communication.

Base Station –The term "Base Station" has the full breadth of its ordinary meaning, and at least includes a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system or radio system.

Processing Element (or Processor) –refers to various elements or combinations of elements that are capable of performing a function in a device, such as a user equipment or a cellular network device. Processing elements may include, for example: processors and associated memory, portions or circuits of individual processor cores, entire processor cores, processor arrays, circuits such as an ASIC (Application Specific Integrated Circuit) , programmable hardware elements such as a field programmable gate array (FPGA) , as well any of various combinations of the above.

Channel -a medium used to convey information from a sender (transmitter) to a receiver. It should be noted that since characteristics of the term “channel” may differ according to different wireless protocols, the term “channel” as used herein may be considered as being used in a manner that is consistent with the standard of the type of device with reference to which the term is used. In some standards, channel widths may be variable (e.g., depending on device capability, band conditions, etc. ) . For example, LTE may support scalable channel bandwidths from 1.4 MHz to 20MHz. 5G NR can support scalable channel bandwidths from 5 MHz to 100 MHz in Frequency Range 1 (FR1) and up to 400 MHz in FR2. In other radio access technologies, WLAN channels may be 22 MHz wide while Bluetooth channels may be 1 MHz wide. Other protocols and standards may include different definitions of channels. Furthermore, some standards may define and use multiple types of channels, e.g., different channels for uplink or downlink and/or different channels for different uses such as data, control information, etc.

Band -The term "band" has the full breadth of its ordinary meaning, and at least includes a section of spectrum (e.g., radio frequency spectrum) in which channels are used or set aside for the same purpose.

Automatically –refers to an action or operation performed by a computer system (e.g., software executed by the computer system) or device (e.g., circuitry, programmable hardware elements, ASICs, etc. ) , without user input directly specifying or performing the action or operation. Thus, the term "automatically" is in contrast to an operation being manually performed or specified by the user, where the user provides input to directly perform the operation. An automatic procedure may be initiated by input provided by the user, but the subsequent actions that are performed “automatically” are not specified by the user, i.e., are not performed “manually” , where the user specifies each action to perform. For example, a user filling out an electronic form by selecting each field and providing input specifying information (e.g., by typing information, selecting check boxes, radio selections, etc. ) is filling out the form manually, even though the computer system will update the form in response to the user actions. The form may be automatically filled out by the computer system where the computer system (e.g., software executing on the computer system) analyzes the fields of the form and fills in the form without any user input specifying the answers to the fields. As indicated above, the user may invoke the automatic filling of the form, but is not involved in the actual filling of the form (e.g., the user is not manually specifying answers to fields but rather they are being automatically completed) . The present specification provides various examples of operations being automatically performed in response to actions the user has taken.

Approximately -refers to a value that is almost correct or exact. For example, approximately may refer to a value that is within 1 to 10 percent of the exact (or desired) value. It should be noted, however, that the actual threshold value (or tolerance) may be application dependent. For example, in some embodiments, “approximately” may mean within 0.1%of some specified or desired value, while in various other embodiments, the threshold may be, for example, 2%, 3%, 5%, and so forth, as desired or as set by the particular application.

Concurrent –refers to parallel execution or performance, where tasks, processes, or programs are performed in an at least partially overlapping manner. For example, concurrency may be implemented using “strong” or strict parallelism, where tasks are performed (at least partially) in parallel on respective computational elements, or using “weak parallelism” , where the tasks are performed in an interleaved manner, e.g., by time multiplexing of execution threads.

Legacy -The 3rd Generation Partnership Project (3GPP) produces specifications that define 3GPP technologies. 3GPP specifications cover cellular telecommunications technologies, including radio access, core network and service capabilities, which provide a complete system description for mobile telecommunications. 3GPP uses a system of parallel “Releases” that provide developers with a stable platform for the implementation of features at a given point and then allow for the addition of new functionality in subsequent releases. Release 17 was released in 2022. Release 18 (Rel-18) , at the time of this disclosure, is nearing release on June 22, 2024, as its specifications have been largely defined. Accordingly, implementations and concepts compatible with Rel-18, or previous Releases, are sometimes referred to herein as “Legacy Releases. ” One or more embodiments of the present disclosure may be adopted in future Releases, e.g., Release 19.

Centralized Unit and Distributed Unit –A base station such as a gNB can be divided into physical entities named a centralized unit (CU) and a distributed unit (DU) . The CU can provide support for higher layers of a protocol stack, such as a radio resource control (RRC) layer and a packet data convergence protocol (PDCP) layer. The DU can provide support for lower layers of the protocol stack, such as a medium access control (MAC) layer and physical layer. The gNB can have a single CU that is coupled to and controls multiple DUs. Each DU can support one or more cells.

Various components may be described as “configured to” perform a task or tasks. In such contexts, “configured to” is a broad recitation generally meaning “having structure that” performs the task or tasks during operation. As such, the component can be configured to perform the task even when the component is not currently performing that task (e.g., a set of electrical conductors may be configured to electrically connect a module to another module, even when the two modules are not connected) . In some contexts, “configured to” may be a broad recitation of structure generally meaning “having circuitry that” performs the task or tasks during operation. As such, the component can be configured to perform the task even when the component is not currently on. In general, the circuitry that forms the structure corresponding to “configured to” may include hardware circuits.

Various components may be described as performing a task or tasks, for convenience in the description. Such descriptions should be interpreted as including the phrase “configured to. ” Reciting a component that is configured to perform one or more tasks is expressly intended not to invoke 35 U.S.C. § 112 (f) interpretation for that component.

The example embodiments may be further understood with reference to the following description and the related appended drawings, wherein like elements are provided with the same reference numerals. The example embodiments relate to configurations and methods for implementing inter-CU LTM.

The example embodiments are described with regard to communication between a source CU of a next generation Node B (gNB) and candidate CUs to obtain information for target or candidate distributed units (DU) of the candidate CUs for a user equipment (UE) . However, reference to a gNB or a UE is merely provided for illustrative purposes. The example embodiments may be utilized with any electronic component that may establish a connection to a network and is configured with the hardware, software, and/or firmware to support inter-CU LTM. Therefore, the gNB or UE as described herein is used to represent any appropriate type of electronic component.

Throughout this description various information elements (IEs) are referred to by specific names. It should be understood that these names are only examples and the IEs carrying the information referred to throughout this description may be referred to by other names by various entities.

Figures 1A and 1B: Communication Systems

FIG. 1A illustrates a simplified example wireless communication system, according to some embodiments. It is noted that the system of FIG. 1A is merely one example of a possible system, and that features of this disclosure may be implemented in any of various systems, as desired.

As shown, the example wireless communication system includes a base station 102A which communicates over a transmission medium with one or more user devices 106A, 106B, etc., through 106N. Each of the user devices may be referred to herein as a “user equipment” (UE) . Thus, the user devices 106 are referred to as UEs or UE devices.

The base station (BS) 102A may be a base transceiver station (BTS) or cell site (a “cellular base station” ) and may include hardware that enables wireless communication with the UEs 106A through 106N.

The communication area (or coverage area) of the base station may be referred to as a “cell. ” The base station 102A and the UEs 106 may be configured to communicate over the transmission medium using any of various radio access technologies (RATs) , also referred to as wireless communication technologies, or telecommunication standards, such as GSM, UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces) , LTE, LTE-Advanced (LTE-A) , 5G new radio (5G NR) , HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD) , etc. Note that if the base station 102A is implemented in the context of LTE, also referred to as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN, it may alternately be referred to as an 'eNodeB' or ‘eNB’ . Note that if the base station 102A is implemented in the context of 5G NR, it may alternately be referred to as ‘gNodeB’ or ‘gNB’ .

As shown, the base station 102A may also be equipped to communicate with a network 100 (e.g., a core network of a cellular service provider, a telecommunication network such as a public switched telephone network (PSTN) , and/or the Internet, among various possibilities) . Thus, the base station 102A may facilitate communication between the user devices and/or between the user devices and the network 100. In particular, the cellular base station 102A may provide UEs 106 with various telecommunication capabilities, such as voice, SMS and/or data services.

Base station 102A and other similar base stations (such as base stations 102B…102N) operating according to the same or a different cellular communication standard may thus be provided as a network of cells, which may provide continuous or nearly continuous overlapping service to UEs 106A-N and similar devices over a geographic area via one or more cellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs 106A-N as illustrated in FIG. 1A, each UE 106 may also be capable of receiving signals from (and possibly within communication range of) one or more other cells (which might be provided by base stations 102B-N and/or any other base stations) , which may be referred to as “neighboring cells” . Such cells may also be capable of facilitating communication between user devices and/or between user devices and the network 100. Such cells may include “macro” cells, “micro” cells, “pico” cells, and/or cells which provide any of various other granularities of service area size. For example, base stations 102A-B illustrated in FIG. 1A might be macro cells, while base station 102N might be a micro cell. Other configurations are also possible.

In some embodiments, base station 102A may be a next generation base station, e.g., a 5G New Radio (5G NR) base station, or “gNB” . In some embodiments, a gNB may be connected to a legacy evolved packet core (EPC) network and/or to a NR core (NRC) network. In addition, a gNB cell may include one or more transition and reception points (TRPs) . In addition, a UE capable of operating according to 5G NR may be connected to one or more TRPs within one or more gNBs.

Note that a UE 106 may be capable of communicating using multiple wireless communication standards. For example, the UE 106 may be configured to communicate using a wireless networking (e.g., Wi-Fi) and/or peer-to-peer wireless communication protocol (e.g., Bluetooth, Wi-Fi peer-to-peer, etc. ) in addition to at least one cellular communication protocol (e.g., GSM, UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces) , LTE, LTE-A, 5G NR, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD) , etc. ) . The UE 106 may also or alternatively be configured to communicate using one or more global navigational satellite systems (GNSS, e.g., GPS or GLONASS) , one or more mobile television broadcasting standards (e.g., ATSC-M/H or DVB-H) , and/or any other wireless communication protocol, if desired. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

FIG. 1B illustrates user equipment 106 (e.g., one of the devices 106A through 106N) in communication with a base station 102 and an access point 112, according to some embodiments. The UE 106 may be a device with both cellular communication capability and non-cellular communication capability (e.g., Bluetooth, Wi-Fi, and so forth) such as a mobile phone, a hand-held device, a computer or a tablet, or virtually any type of wireless device.

The UE 106 may include a processor that is configured to execute program instructions stored in memory. The UE 106 may perform any of the method embodiments described herein by executing such stored instructions. Alternatively, or in addition, the UE 106 may include a programmable hardware element such as an FPGA (field-programmable gate array) that is configured to perform any of the method embodiments described herein, or any portion of any of the method embodiments described herein.

The UE 106 may include one or more antennas for communicating using one or more wireless communication protocols or technologies. In some embodiments, the UE 106 may be configured to communicate using, for example, CDMA2000 (1xRTT /1xEV-DO /HRPD /eHRPD) , LTE/LTE-Advanced, or 5G NR using a single shared radio and/or GSM, LTE, LTE-Advanced, or 5G NR using the single shared radio. The shared radio may couple to a single antenna, or may couple to multiple antennas (e.g., for MIMO) for performing wireless communications. In general, a radio may include any combination of a baseband processor, analog RF signal processing circuitry (e.g., including filters, mixers, oscillators, amplifiers, etc. ) , or digital processing circuitry (e.g., for digital modulation as well as other digital processing) . Similarly, the radio may implement one or more receive and transmit chains using the aforementioned hardware. For example, the UE 106 may share one or more parts of a receive and/or transmit chain between multiple wireless communication technologies, such as those discussed above.

In some embodiments, the UE 106 may include separate transmit and/or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As a further possibility, the UE 106 may include one or more radios which are shared between multiple wireless communication protocols, and one or more radios which are used exclusively by a single wireless communication protocol. For example, the UE 106 might include a shared radio for communicating using either of LTE or 5G NR (or LTE or 1xRTTor LTE or GSM) , and separate radios for communicating using each of Wi-Fi and Bluetooth. Other configurations are also possible.

FIG. 2: Block Diagram of a Base Station

FIG. 2 illustrates an example block diagram of a base station 102, according to some embodiments. It is noted that the base station of FIG. 2 is merely one example of a possible base station. As shown, the base station 102 may include processor (s) 204 which may execute program instructions for the base station 102. The processor (s) 204 may also be coupled to memory management unit (MMU) 240, which may be configured to receive addresses from the processor (s) 204 and translate those addresses to locations in memory (e.g., memory 260 and read only memory (ROM) 250) or to other circuits or devices.

The base station 102 may include at least one network port 270. The network port 270 may be configured to couple to a telephone network and provide a plurality of devices, such as UE devices 106, access to the telephone network as described above in Figures 1 and 2.

The network port 270 (or an additional network port) may also or alternatively be configured to couple to a cellular network, e.g., a core network of a cellular service provider. The core network may provide mobility related services and/or other services to a plurality of devices, such as UE devices 106. In some cases, the network port 270 may couple to a telephone network via the core network, and/or the core network may provide a telephone network (e.g., among other UE devices serviced by the cellular service provider) .

In some embodiments, base station 102 may be a next generation base station, e.g., a 5G New Radio (5G NR) base station, or “gNB” . In such embodiments, base station 102 may be connected to a legacy evolved packet core (EPC) network and/or to a NR core (NRC) network. In addition, base station 102 may be considered a 5G NR cell and may include one or more transition and reception points (TRPs) . In addition, a UE capable of operating according to 5G NR may be connected to one or more TRPs within one or more gNBs.

The base station 102 may include at least one antenna 234, and possibly multiple antennas. The at least one antenna 234 may be configured to operate as a wireless transceiver and may be further configured to communicate with UE devices 106 via radio 230. The antenna 234 communicates with the radio 230 via communication chain 232. Communication chain 232 may be a receive chain, a transmit chain or both. The radio 230 may be configured to communicate via various wireless communication standards, including, but not limited to, 5G NR, LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, etc.

The base station 102 may be configured to communicate wirelessly using multiple wireless communication standards. In some instances, the base station 102 may include multiple radios, which may enable the base station 102 to communicate according to multiple wireless communication technologies. For example, as one possibility, the base station 102 may include an LTE radio for performing communication according to LTE as well as a 5G NR radio for performing communication according to 5G NR. In such a case, the base station 102 may be capable of operating as both an LTE base station and a 5G NR base station. As another possibility, the base station 102 may include a multi-mode radio which is capable of performing communications according to any of multiple wireless communication technologies (e.g., 5G NR and Wi-Fi, LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc. ) .

As described further subsequently herein, the BS 102 may include hardware and software components for implementing or supporting implementation of features described herein. The processor 204 of the base station 102 may be configured to implement or support implementation of part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium) . Alternatively, the processor 204 may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array) , or as an ASIC (Application Specific Integrated Circuit) , or a combination thereof. Alternatively (or in addition) the processor 204 of the BS 102, in conjunction with one or more of the other components 230, 232, 234, 240, 250, 260, 270 may be configured to implement or support implementation of part or all of the features described herein.

In addition, as described herein, processor (s) 204 may be comprised of one or more processing elements. In other words, one or more processing elements may be included in processor (s) 204. Thus, processor (s) 204 may include one or more integrated circuits (ICs) that are configured to perform the functions of processor (s) 204. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of processor (s) 204.

Further, as described herein, radio 230 may be comprised of one or more processing elements. In other words, one or more processing elements may be included in radio 230. Thus, radio 230 may include one or more integrated circuits (ICs) that are configured to perform the functions of radio 230. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of radio 230.

In some embodiments, the base station or gNB 102, and/or processors 204 thereof, can be capable of and configured to determine, at a source centralized unit (CU) of the gNB, one or more candidate CUs for a user equipment (UE) 106; send a handover requess from the source CU of the gNB to the one or more candidate CUs; receive handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB with information regarding candidate distributed units (DUs) coupled to the one or more candidate CUs, to form a list of candidate DUs; assign, at the source CU of the gNB, indices for the candidate DUs coupled to the one or more candidate CUs; and encode, at the source CU of the gNB, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU of the gNB.

FIG. 3: Block Diagram of a Server

FIG. 3 illustrates an example block diagram of a server 104, according to some embodiments. It is noted that the server of FIG. 3 is merely one example of a possible server. As shown, the server 104 may include processor (s) 344 which may execute program instructions for the server 104. The processor (s) 344 may also be coupled to memory management unit (MMU) 374, which may be configured to receive addresses from the processor (s) 344 and translate those addresses to locations in memory (e.g., memory 364 and read only memory (ROM) 354) or to other circuits or devices.

The server 104 may be configured to provide a plurality of devices, such as base station 102, and UE devices 106 access to network functions, e.g., as further described herein.

In some embodiments, the server 104 may be part of a radio access network, such as a 5G New Radio (5G NR) radio access network. In some embodiments, the server 104 may be connected to a legacy evolved packet core (EPC) network and/or to a NR core (NRC) network.

As described herein, the server 104 may include hardware and software components for implementing or supporting implementation of features described herein. The processor 344 of the server 104 may be configured to implement or support implementation of part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium) . Alternatively, the processor 344 may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array) , or as an ASIC (Application Specific Integrated Circuit) , or a combination thereof. Alternatively (or in addition) the processor 344 of the server 104, in conjunction with one or more of the other components 354, 364, and/or 374 may be configured to implement or support implementation of part or all of the features described herein.

In addition, as described herein, processor (s) 344 may be comprised of one or more processing elements. In other words, one or more processing elements may be included in processor (s) 344. Thus, processor (s) 344 may include one or more integrated circuits (ICs) that are configured to perform the functions of processor (s) 344. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of processor (s) 344.

FIG. 4: Block Diagram of a UE

FIG. 4 illustrates an example simplified block diagram of a communication device 106, according to some embodiments. It is noted that the block diagram of the communication device of FIG. 4 is only one example of a possible communication device. According to embodiments, communication device 106 may be a user equipment (UE) device, a mobile device or mobile station, a wireless device or wireless station, a desktop computer or computing device, a mobile computing device (e.g., a laptop, notebook, or portable computing device) , a tablet, an unmanned aerial vehicle (UAV) , a UAV controller (UAC) and/or a combination of devices, among other devices. As shown, the communication device 106 may include a set of components 400 configured to perform core functions. For example, this set of components may be implemented as a system on chip (SOC) , which may include portions for various purposes. Alternatively, this set of components 400 may be implemented as separate components or groups of components for the various purposes. The set of components 400 may be coupled (e.g., communicatively; directly or indirectly) to various other circuits of the communication device 106.

For example, the communication device 106 may include various types of memory (e.g., including NAND flash 410) , an input/output interface such as connector I/F 420 (e.g., for connecting to a computer system; dock; charging station; input devices, such as a microphone, camera, keyboard; output devices, such as speakers; etc. ) , the display 460, which may be integrated with or external to the communication device 106, and cellular communication circuitry 430 such as for 5G NR, LTE, GSM, etc., and short to medium range wireless communication circuitry 429 (e.g., Bluetooth^TM and WLAN circuitry) . In some embodiments, communication device 106 may include wired communication circuitry (not shown) , such as a network interface card, e.g., for Ethernet.

The cellular communication circuitry 430 may couple (e.g., communicatively; directly or indirectly) to one or more antennas, such as antennas 435 and 436 as shown. The short to medium range wireless communication circuitry 429 may also couple (e.g., communicatively; directly or indirectly) to one or more antennas, such as antennas 437 and 438 as shown. Alternatively, the short to medium range wireless communication circuitry 429 may couple (e.g., communicatively; directly or indirectly) to the antennas 435 and 436 in addition to, or instead of, coupling (e.g., communicatively; directly or indirectly) to the antennas 437 and 438. The short to medium range wireless communication circuitry 429 and/or cellular communication circuitry 430 may include multiple receive chains and/or multiple transmit chains for receiving and/or transmitting multiple spatial streams, such as in a multiple-input multiple output (MIMO) configuration.

In some embodiments, as further described below, cellular communication circuitry 430 may include dedicated receive chains (including and/or coupled to, e.g., communicatively; directly or indirectly. dedicated processors and/or radios) for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for 5G NR) . In addition, in some embodiments, cellular communication circuitry 430 may include a single transmit chain that may be switched between radios dedicated to specific RATs. For example, a first radio may be dedicated to a first RAT, e.g., LTE, and may be in communication with a dedicated receive chain and a transmit chain shared with an additional radio, e.g., a second radio that may be dedicated to a second RAT, e.g., 5G NR, and may be in communication with a dedicated receive chain and the shared transmit chain.

The communication device 106 may also include and/or be configured for use with one or more user interface elements. The user interface elements may include any of various elements, such as display 460 (which may be a touchscreen display) , a keyboard (which may be a discrete keyboard or may be implemented as part of a touchscreen display) , a mouse, a microphone and/or speakers, one or more cameras, one or more buttons, and/or any of various other elements capable of providing information to a user and/or receiving or interpreting user input.

The communication device 106 may further include one or more smart cards 445 that include SIM (Subscriber Identity Module) functionality, such as one or more UICC (s) (Universal Integrated Circuit Card (s) ) cards 445. Note that the term “SIM” or “SIM entity” is intended to include any of various types of SIM implementations or SIM functionality, such as the one or more UICC (s) cards 445, one or more eUICCs, one or more eSIMs, either removable or embedded, etc. In some embodiments, the UE 106 may include at least two SIMs. Each SIM may execute one or more SIM applications and/or otherwise implement SIM functionality. Thus, each SIM may be a single smart card that may be embedded, e.g., may be soldered onto a circuit board in the UE 106, or each SIM 410 may be implemented as a removable smart card. Thus, the SIM (s) may be one or more removable smart cards (such as UICC cards, which are sometimes referred to as “SIM cards” ) , and/or the SIMs 410 may be one or more embedded cards (such as embedded UICCs (eUICCs) , which are sometimes referred to as “eSIMs” or “eSIM cards” ) . In some embodiments (such as when the SIM (s) include an eUICC) , one or more of the SIM (s) may implement embedded SIM (eSIM) functionality; in such an embodiment, a single one of the SIM (s) may execute multiple SIM applications. Each of the SIMs may include components such as a processor and/or a memory; instructions for performing SIM/eSIM functionality may be stored in the memory and executed by the processor. In some embodiments, the UE 106 may include a combination of removable smart cards and fixed/non-removable smart cards (such as one or more eUICC cards that implement eSIM functionality) , as desired. For example, the UE 106 may comprise two embedded SIMs, two removable SIMs, or a combination of one embedded SIMs and one removable SIMs. Various other SIM configurations are also contemplated.

As noted above, in some embodiments, the UE 106 may include two or more SIMs. The inclusion of two or more SIMs in the UE 106 may allow the UE 106 to support two different telephone numbers and may allow the UE 106 to communicate on corresponding two or more respective networks. For example, a first SIM may support a first RAT such as LTE, and a second SIM 410 support a second RAT such as 5G NR. Other implementations and RATs are of course possible. In some embodiments, when the UE 106 comprises two SIMs, the UE 106 may support Dual SIM Dual Active (DSDA) functionality. The DSDA functionality may allow the UE 106 to be simultaneously connected to two networks (and use two different RATs) at the same time, or to simultaneously maintain two connections supported by two different SIMs using the same or different RATs on the same or different networks. The DSDA functionality may also allow the UE 106 to simultaneously receive voice calls or data traffic on either phone number. In certain embodiments the voice call may be a packet switched communication. In other words, the voice call may be received using voice over LTE (VoLTE) technology and/or voice over NR (VoNR) technology. In some embodiments, the UE 106 may support Dual SIM Dual Standby (DSDS) functionality. The DSDS functionality may allow either of the two SIMs in the UE 106 to be on standby waiting for a voice call and/or data connection. In DSDS, when a call/data is established on one SIM, the other SIM is no longer active. In some embodiments, DSDx functionality (either DSDA or DSDS functionality) may be implemented with a single SIM (e.g., a eUICC) that executes multiple SIM applications for different carriers and/or RATs.

As shown, the SOC 400 may include processor (s) 402, which may execute program instructions for the communication device 106 and display circuitry 404, which may perform graphics processing and provide display signals to the display 460. The processor (s) 402 may also be coupled to memory management unit (MMU) 440, which may be configured to receive addresses from the processor (s) 402 and translate those addresses to locations in memory (e.g., memory 406, read only memory (ROM) 450, NAND flash memory 410) and/or to other circuits or devices, such as the display circuitry 404, short to medium range wireless communication circuitry 429, cellular communication circuitry 430, connector I/F 420, and/or display 460. The MMU 440 may be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU 440 may be included as a portion of the processor (s) 402.

As described herein, the communication device 106 may include hardware and software components for implementing the above features for a communication device 106 to communicate a scheduling profile for power savings to a network. The processor 402 of the communication device 106 may be configured to implement part or all of the features described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium) . Alternatively (or in addition) , processor 402 may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array) , or as an ASIC (Application Specific Integrated Circuit) . Alternatively (or in addition) the processor 402 of the communication device 106, in conjunction with one or more of the other components 400, 404, 406, 410, 420, 429, 430, 440, 445, 450, 460 may be configured to implement part or all of the features described herein.

In addition, as described herein, processor 402 may include one or more processing elements. Thus, processor 402 may include one or more integrated circuits (ICs) that are configured to perform the functions of processor 402. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of processor (s) 402.

Further, as described herein, cellular communication circuitry 430 and short to medium range wireless communication circuitry 429 may each include one or more processing elements. In other words, one or more processing elements may be included in cellular communication circuitry 430 and, similarly, one or more processing elements may be included in short to medium range wireless communication circuitry 429. Thus, cellular communication circuitry 430 may include one or more integrated circuits (ICs) that are configured to perform the functions of cellular communication circuitry 430. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of cellular communication circuitry 430. Similarly, the short to medium range wireless communication circuitry 429 may include one or more ICs that are configured to perform the functions of short to medium range wireless communication circuitry 429. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of short to medium range wireless communication circuitry 429.

FIG. 5: Block Diagram of Cellular Communication Circuitry

FIG. 5 illustrates an example simplified block diagram of cellular communication circuitry, according to some embodiments. It is noted that the block diagram of the cellular communication circuitry of FIG. 5 is only one example of a possible cellular communication circuit. According to embodiments, cellular communication circuitry 530, which may be cellular communication circuitry 430, may be included in a communication device, such as communication device 106 described above. As noted above, communication device 106 may be a user equipment (UE) device, a mobile device or mobile station, a wireless device or wireless station, a desktop computer or computing device, a mobile computing device (e.g., a laptop, notebook, or portable computing device) , a tablet and/or a combination of devices, among other devices.

The cellular communication circuitry 530 may couple (e.g., communicatively; directly or indirectly) to one or more antennas, such as antennas 435a-b and 436 as shown (in FIG. 4) . In some embodiments, cellular communication circuitry 530 may include dedicated receive chains (including and/or coupled to, e.g., communicatively; directly or indirectly. dedicated processors and/or radios) for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for 5G NR) . For example, as shown in FIG. 5, cellular communication circuitry 530 may include a modem 510 and a modem 520. Modem 510 may be configured for communications according to a first RAT, e.g., such as LTE or LTE-A, and modem 520 may be configured for communications according to a second RAT, e.g., such as 5G NR.

As shown, modem 510 may include one or more processors 512 and a memory 516 in communication with processors 512. Modem 510 may be in communication with a radio frequency (RF) front end 530. RF front end 530 may include circuitry for transmitting and receiving radio signals. For example, RF front end 530 may include receive circuitry (RX) 532 and transmit circuitry (TX) 534. In some embodiments, receive circuitry 532 may be in communication with downlink (DL) front end 550, which may include circuitry for receiving radio signals via antenna 335a.

Similarly, modem 520 may include one or more processors 522 and a memory 526 in communication with processors 522. Modem 520 may be in communication with an RF front end 540. RF front end 540 may include circuitry for transmitting and receiving radio signals. For example, RF front end 540 may include receive circuitry 542 and transmit circuitry 544. In some embodiments, receive circuitry 542 may be in communication with DL front end 560, which may include circuitry for receiving radio signals via antenna 335b.

In some embodiments, a switch 570 may couple transmit circuitry 534 to uplink (UL) front end 572. In addition, switch 570 may couple transmit circuitry 544 to UL front end 572. UL front end 572 may include circuitry for transmitting radio signals via antenna 336. Thus, when cellular communication circuitry 530 receives instructions to transmit according to the first RAT (e.g., as supported via modem 510) , switch 570 may be switched to a first state that allows modem 510 to transmit signals according to the first RAT (e.g., via a transmit chain that includes transmit circuitry 534 and UL front end 572) . Similarly, when cellular communication circuitry 530 receives instructions to transmit according to the second RAT (e.g., as supported via modem 520) , switch 570 may be switched to a second state that allows modem 520 to transmit signals according to the second RAT (e.g., via a transmit chain that includes transmit circuitry 544 and UL front end 572) .

As described herein, the modem 510 may include hardware and software components for implementing the above features or for time division multiplexing UL data for NSA NR operations, as well as the various other techniques described herein. The processors 512 may be configured to implement part or all of the features described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium) . Alternatively (or in addition) , processor 512 may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array) , or as an ASIC (Application Specific Integrated Circuit) . Alternatively (or in addition) the processor 512, in conjunction with one or more of the other components 530, 532, 534, 550, 570, 572, 335a, 335b, and 336 may be configured to implement part or all of the features described herein.

In addition, as described herein, processors 512 may include one or more processing elements. Thus, processors 512 may include one or more integrated circuits (ICs) that are configured to perform the functions of processors 512. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of processors 512.

The processors 522 may be configured to implement part or all of the features described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium) . Alternatively (or in addition) , processor 522 may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array) , or as an ASIC (Application Specific Integrated Circuit) . Alternatively (or in addition) the processor 522, in conjunction with one or more of the other components 540, 542, 544, 550, 570, 572, 335a, 335b, and 336 may be configured to implement part or all of the features described herein.

In addition, as described herein, processors 522 may include one or more processing elements. Thus, processors 522 may include one or more integrated circuits (ICs) that are configured to perform the functions of processors 522. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc. ) configured to perform the functions of processors 522.

FIG. 6: Block Diagram of a Baseband Processor Architecture for a UE

FIG. 6 illustrates example components of a device 600 in accordance with some embodiments. It is noted that the device of FIG. 6 is merely one example of a possible system, and that features of this disclosure may be implemented in any of various UEs, as desired.

In some embodiments, the device 600 may include application circuitry 602, baseband circuitry 604, Radio Frequency (RF) circuitry 606, front-end module (FEM) circuitry 608, one or more antennas 610, and power management circuitry (PMC) 612 coupled together at least as shown. The components of the illustrated device 600 may be included in a UE 106 or a RAN node. In some embodiments, the device 600 may include less elements (e.g., a RAN node may not utilize application circuitry 602, and instead include a processor/controller to process IP data received from an EPC) . In some embodiments, the device 600 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C-RAN) implementations) .

The application circuitry 602 may include one or more application processors. For example, the application circuitry 602 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor (s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc. ) . The processors may be coupled with or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the device 600. In some embodiments, processors of application circuitry 602 may process IP data packets received from an EPC.

The baseband circuitry 604 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 604 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 606 and to generate baseband signals for a transmit signal path of the RF circuitry 606. Baseband processing circuity 604 may interface with the application circuitry 602 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 606. For example, in some embodiments, the baseband circuitry 604 may include a third generation (3G) baseband processor 604A, a fourth generation (4G) baseband processor 604B, a fifth generation (5G) baseband processor 604C, or other baseband processor (s) 604D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G) , sixth generation (6G) , etc. ) . The baseband circuitry 604 (e.g., one or more of baseband processors 604A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 606. In other embodiments, some or all of the functionality of baseband processors 604A-D may be included in modules stored in the memory 604G and executed via a Central Processing Unit (CPU) 604E. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 604 may include Fast-Fourier Transform (FFT) , precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 604 may include convolution, tail-biting convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry 604 may include one or more audio digital signal processor (s) (DSP) 604F. The audio DSP (s) 604F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 604 and the application circuitry 602 may be implemented together such as, for example, on a system on a chip (SOC) .

In some embodiments, the baseband circuitry 604 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 604 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry 604 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

RF circuitry 606 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 606 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 606 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 608 and provide baseband signals to the baseband circuitry 604. RF circuitry 606 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 604 and provide RF output signals to the FEM circuitry 608 for transmission.

In some embodiments, the receive signal path of the RF circuitry 606 may include mixer circuitry 606a, amplifier circuitry 606b and filter circuitry 606c. In some embodiments, the transmit signal path of the RF circuitry 606 may include filter circuitry 606c and mixer circuitry 606a. RF circuitry 606 may also include synthesizer circuitry 606d for synthesizing a frequency for use by the mixer circuitry 606a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 606a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 608 based on the synthesized frequency provided by synthesizer circuitry 606d. The amplifier circuitry 606b may be configured to amplify the down-converted signals and the filter circuitry 606c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 604 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a necessity. In some embodiments, mixer circuitry 606a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 606a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 606d to generate RF output signals for the FEM circuitry 608. The baseband signals may be provided by the baseband circuitry 604 and may be filtered by filter circuitry 606c.

In some embodiments, the mixer circuitry 606a of the receive signal path and the mixer circuitry 606a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 606a of the receive signal path and the mixer circuitry 606a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection) . In some embodiments, the mixer circuitry 606a of the receive signal path and the mixer circuitry 606a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 606a of the receive signal path and the mixer circuitry 606a of the transmit signal path may be configured for super-heterodyne operation.

In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 606 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 604 may include a digital baseband interface to communicate with the RF circuitry 606.

In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 606d may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 606d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

The synthesizer circuitry 606d may be configured to synthesize an output frequency for use by the mixer circuitry 606a of the RF circuitry 606 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 606d may be a fractional N/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO) , although that is not a necessity. Divider control input may be provided by either the baseband circuitry 604 or the applications processor 602 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 602.

Synthesizer circuitry 606d of the RF circuitry 606 may include a divider, a delay-locked loop (DLL) , a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA) . In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 606d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO) . In some embodiments, the RF circuitry 606 may include an IQ/polar converter.

FEM circuitry 608 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 610, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 606 for further processing. FEM circuitry 608 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 606 for transmission by one or more of the one or more antennas 610. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 606, solely in the FEM 608, or in both the RF circuitry 606 and the FEM 608.

In some embodiments, the FEM circuitry 608 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 606) . The transmit signal path of the FEM circuitry 608 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 606) , and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 610) .

In some embodiments, the PMC 612 may manage power provided to the baseband circuitry 604. In particular, the PMC 612 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 612 may often be included when the device 600 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 612 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

While FIG. 6 shows the PMC 612 coupled only with the baseband circuitry 604, in other embodiments the PMC 612 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 602, RF circuitry 606, or FEM 608.

In some embodiments, the PMC 612 may control, or otherwise be part of, various power saving mechanisms of the device 600. For example, if the device 600 is in a radio resource control_Connected (RRC_Connected) state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 600 may power down for brief intervals of time and thus save power.

If there is no data traffic activity for an extended period of time, then the device 600 may transition off to an RRC_Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 600 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 600 may not receive data in this state, in order to receive data, it will transition back to RRC_Connected state.

An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours) . During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

Processors of the application circuitry 602 and processors of the baseband circuitry 604 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 604, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 604 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers) . As referred to herein, Layer 3 (L3) may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 (L2) may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 (L1) may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below. Accordingly, the baseband circuitry 604 can be used to encode a message for transmission between a UE and a gNB, or decode a message received between a UE and a gNB.

FIG. 7: Block Diagram of an Interface of Baseband Circuitry

FIG. 7 illustrates example interfaces of baseband circuitry in accordance with some embodiments. It is noted that the baseband circuitry of FIG. 7 is merely one example of a possible circuitry, and that features of this disclosure may be implemented in any of various systems, as desired.

As discussed above, the baseband circuitry 604 of FIG. 6 may comprise processors 604A-604E and a memory 604G utilized by said processors. Each of the processors 604A-604E may include a memory interface, 704A-704E, respectively, to send/receive data to/from the memory 604G.

The baseband circuitry 604 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 712 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 604) , an application circuitry interface 714 (e.g., an interface to send/receive data to/from the application circuitry 602 of FIG. 6) , an RF circuitry interface 716 (e.g., an interface to send/receive data to/from RF circuitry 606 of FIG. 6) , a wireless hardware connectivity interface 718 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, components (e.g., Low Energy) , components, and other communication components) , and a power management interface 720 (e.g., an interface to send/receive power or control signals to/from the PMC 612.

FIG. 8: Control Plane Protocol Stack

FIG. 8 is an illustration of a control plane protocol stack in accordance with some embodiments. In this embodiment, a control plane 800 is shown as a communications protocol stack between the UE 106a (or alternatively, the UE 106b) , the RAN node 611 (or alternatively, the RAN node 612) , and the mobility management entity (MME) 621.

The PHY layer 801 may transmit or receive information used by the MAC layer 802 over one or more air interfaces. The PHY layer 801 may further perform link adaptation or adaptive modulation and coding (AMC) , power control, cell search (e.g., for initial synchronization and handover purposes) , and other measurements used by higher layers, such as the RRC layer 805. The PHY layer 801 may still further perform error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, modulation/demodulation of physical channels, interleaving, rate matching, mapping onto physical channels, and Multiple Input Multiple Output (MIMO) antenna processing.

The MAC layer 802 may perform mapping between logical channels and transport channels, multiplexing of MAC service data units (SDUs) from one or more logical channels onto transport blocks (TB) to be delivered to PHY via transport channels, de-multiplexing MAC SDUs to one or more logical channels from transport blocks (TB) delivered from the PHY via transport channels, multiplexing MAC SDUs onto TBs, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ) , and logical channel prioritization.

The RLC layer 803 may operate in a plurality of modes of operation, including: Transparent Mode (TM) , Unacknowledged Mode (UM) , and Acknowledged Mode (AM) . The RLC layer 803 may execute transfer of upper layer protocol data units (PDUs) , error correction through automatic repeat request (ARQ) for AM data transfers, and concatenation, segmentation and reassembly of RLC SDUs for UM and AM data transfers. The RLC layer 803 may also execute re-segmentation of RLC data PDUs for AM data transfers, reorder RLC data PDUs for UM and AM data transfers, detect duplicate data for UM and AM data transfers, discard RLC SDUs for UM and AM data transfers, detect protocol errors for AM data transfers, and perform RLC re-establishment.

The PDCP layer 804 may execute header compression and decompression of IP data, maintain PDCP Sequence Numbers (SNs) , perform in-sequence delivery of upper layer PDUs at re-establishment of lower layers, eliminate duplicates of lower layer SDUs at re-establishment of lower layers for radio bearers mapped on RLC AM, cipher and decipher control plane data, perform integrity protection and integrity verification of control plane data, control timer-based discard of data, and perform security operations (e.g., ciphering, deciphering, integrity protection, integrity verification, etc. ) .

The main services and functions of the RRC layer 805 may include broadcast of system information (e.g., included in Master Information Blocks (MIBs) or System Information Blocks (SIBs) related to the non-access stratum (NAS) ) , broadcast of system information related to the access stratum (AS) , paging, establishment, maintenance and release of an RRC connection between the UE and E-UTRAN (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release) , establishment, configuration, maintenance and release of point to point Radio Bearers, security functions including key management, inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting. Said MIBs and SIBs may comprise one or more information elements (IEs) , which may each comprise individual data fields or data structures.

The UE 601 and the RAN node 611 may utilize a Uu interface (e.g., an LTE-Uu interface) to exchange control plane data via a protocol stack comprising the PHY layer 801, the MAC layer 802, the RLC layer 803, the PDCP layer 804, and the RRC layer 805.

The non-access stratum (NAS) protocols 806 form the highest stratum of the control plane between the UE 601 and the MME 621. The NAS protocols 806 support the mobility of the UE 601 and the session management procedures to establish and maintain IP connectivity between the UE 601 and the P-GW 623.

The S1 Application Protocol (S1-AP) layer 815 may support the functions of the S1 interface and comprise Elementary Procedures (EPs) . An EP is a unit of interaction between the RAN node 1010 and the CN 1020. The S1-AP layer services may comprise two groups: UE-associated services and non UE- associated services. These services perform functions including, but not limited to: E-UTRAN Radio Access Bearer (E-RAB) management, UE capability indication, mobility, NAS signaling transport, RAN Information Management (RIM) , and configuration transfer.

The Stream Control Transmission Protocol (SCTP) layer (alternatively referred to as the SCTP/IP layer) 814 may ensure reliable delivery of signaling messages between the RAN node 611 and the MME 621 based, in part, on the IP protocol, supported by the IP layer 813. The L2 layer 812 and the L1 layer 811 may refer to communication links (e.g., wired or wireless) used by the RAN node and the MME to exchange information.

The RAN node 611 and the MME 621 may utilize an S1-MME interface to exchange control plane data via a protocol stack comprising the L1 layer 811, the L2 layer 812, the IP layer 813, the SCTP layer 814, and the S1-AP layer 815.

FIG. 9: User Plane Protocol Stack

FIG. 9 is an illustration of an example of a user plane protocol stack in accordance with some embodiments. In this embodiment, a user plane 900 is shown as a communications protocol stack between the UE 106A (or alternatively, the UE 106B or 106N) , the RAN node 611 (or alternatively, the RAN node 612) , the S-GW 622, and the P-GW 623. The user plane 900 may utilize at least some of the same protocol layers as the control plane 800. For example, the UE 601 and the RAN node 611 may utilize a Uu interface (e.g., an LTE-Uu interface) to exchange user plane data via a protocol stack comprising the PHY layer 801, the MAC layer 802, the RLC layer 803, the PDCP layer 804.

The General Packet Radio Service (GPRS) Tunneling Protocol for the user plane (GTP-U) layer 904 may be used for carrying user data within the GPRS core network and between the radio access network and the core network. The user data transported can be packets in any of IPv4, IPv6, or PPP formats, for example. The UDP and IP security (UDP/IP) layer 903 may provide checksums for data integrity, port numbers for addressing different functions at the source and destination, and encryption and authentication on the selected data flows. The RAN node 611 and the S-GW 622 may utilize an S1-U interface to exchange user plane data via a protocol stack comprising the L1 layer 811, the L2 layer 812, the UDP/IP layer 903, and the GTP-U layer 904. The S-GW 622 and the P-GW 623 may utilize an S5/S8a interface to exchange user plane data via a protocol stack comprising the L1 layer 811, the L2 layer 812, the UDP/IP layer 903, and the GTP-U layer 904. As discussed above with respect to FIG. 8, NAS protocols support the mobility of the UE 106 and the session management procedures to establish and maintain IP 913 connectivity between the UE 106 and the P-GW 623.

FIG. 10: Core Network

FIG. 10 illustrates an example architecture of a system 1000 including a core network (CN) 1020 in accordance with various embodiments. The CN 1020 may be a core network for a 5G System (which may be referred to as a 5GC) . The system 1000 is shown to include a UE 1001, which may be the same or similar to the UEs 106A, 106B, or 106N discussed previously; a (R) AN 102, which may be the same or similar to the BSs 102A or 102N discussed previously; and a data network (DN) 1003, which may be, for example, operator services, Internet access, or 3rd party services; and a CN 1020. The CN 1020 may include a number of network functions including an Authentication Server Function (AUSF) 1022; an Access and Mobility Management Function (AMF) 1021; a Session Management Function (SMF) 1024; a Network Exposure Function (NEF) 1023; a Policy Control Function (PCF) 1026; a Network Repository Function (NRF) 1025; a Unified Data Management (UDM) 1027; an Application Function (AF) 1028; a User Plane Function (UPF) 1002; and a Network Slice Selection Function (NSSF) 1029. These network functions may be implemented, in some cases, as virtualized software based functions/services.

The UPF 1002 may act as an anchor point for intra-RAT and inter-RAT mobility, an external packet data unit (PDU) session point of interconnect to DN 1003, and a branching point to support mufti-homed PDU session. A PDU session is a logical connection between the UE and the DN. The UPF 1002 may also perform packet routing and forwarding, perform packet inspection, enforce the user plane part of policy rules, lawfully intercept packets (user plane (UP) collection) , perform traffic usage reporting, perform quality of service (QoS) handling for a user plane (e.g., packet filtering, gating, UL/DL rate enforcement) , perform Uplink Traffic verification (e.g., Service Data Flows (SDF) to QoS flow mapping) , transport level packet marking in the uplink and downlink, and perform downlink packet buffering and downlink data notification triggering. UPF 1002 may include an uplink classifier to support routing traffic flows to a data network, The DN 1003 may represent various network operator services, Internet access, or third party services. DN 1003 may include, or be similar to, application server 430 discussed previously. The UPF 1002 may interact with the SMF 1024 via an N4 reference point between the SMF 1021 and the UPF 1002.

The AUSF 1022 may store data for authentication of UE 1001 and handle authentication-related functionality, The AUSF 1022 may facilitate a common authentication frame work for various access types. The AUSF 1022 may communicate with the AMF 1021 via an N12 reference point between the AMF 1021 and the AUSF 1022; and may communicate with the UDM 1027 via an N13 reference point between the UDM 1027 and the AUSF 1022. Additionally, the AUSF 1022 may exhibit an Nausf service-based interface.

The AMF 1021 may be responsible for registration management (e.g., for registering UE 1001, etc. ) , connection management, reachability management, mobility management, and lawful interception of AMF-related events, and access authentication and authorization. The AMF 1021 may be a termination point for the an N11 reference point between the AMF 1021 and the SMF 1024. The AMF 1021 may provide transport for SM messages between the UE 1001 and the SMF 1024, and act as a transparent proxy for routing SM messages. AMF 1021 may also provide transport for Short Message Service (SMS) messages between UE 1001 and an SMSF (not shown by FIG. 10) . AMF 1021 may act as a security anchor function (SEAF) , which may include interaction with the AUSF 1022 and the UE 1001, receipt of an intermediate key that was established as a result of the UE 1001 authentication process. Where Universal Subscriber Identity Module (USIM) based authentication is used, the AMF 1021 may retrieve the security material from the AUSF 1022. AMF 1021 may also include a Security Context Management (SCM) function, which receives a key from the SEAF that it uses to derive access-network specific keys. Furthermore, AMF 1021 may be a termination point of a RAN control plane (CP) interface, which may include or be an N2 reference point between the (R) AN 1010 and the AMF 1021; and the AMF 1021 may be a termination point of NAS (Nl) signaling, and perform NAS ciphering and integrity protection.

AMF 1021 may also support NAS signaling with a UE 1001 over a non-3GPP Inter-Working Function (N3IWF) interface. The N3IWF may be used to provide access to untrusted entities. N3IWF may be a termination point for the N2 interface between the (R) AN 1010 and the AMF 1021 for the control plane, and may be a termination point for the N3 reference point between the (R) AN 1010 and the UPF 1002 for the user plane. As such, the AMF 1021 may handle N2 signaling from the SMF 1024 and the AMF 1021 for PDU sessions and encapsulate/de-encapsulate packets for IPSec and N3 tunneling, mark N3 user-plane packets in the uplink, and enforce QoS corresponding to N3 packet marking while considering QoS requirements associated with such marking received over N2. N3IWF may also relay uplink and downlink control plane non-access stratum (NAS) signaling between the UE 1001 and AMF 1021 via an N1 reference point between the UE 1001 and the AMF 1021, and relay uplink and downlink user-plane packets between the UE 1001 and UPF 1002. The N3IWF also provides mechanisms for internet protocol security (IPsec) tunnel establishment with the UE 1001. The AMF 1021 may exhibit an Namf service based interface, and may be a termination point for an N14 reference point between two AMFs 1021 and an N17 reference point between the AMF 1021 and a 5G Equipment Identity Register (5G-EIR) (not shown by FIG. 10) .

The UE 1001 may need to register with the AMF 1021 in order to receive network services. Registration Management (RM) is used to register or deregister the UE 1001 with the network (e.g., AMF 1021) , and establish a UE context in the network (e.g., AMF 1021) . The UF 1001 may operate in an RM-REGISTERED state or an RM-DEREGISTERED state. In the RM-DEREGISTERED state, the UE 1001 is not registered with the network, and the UE context in AMF 1021 holds no valid location or routing information for the UE 1001 so the UE 1001 is not reachable by the AMF 1021. In the RM REGISTERED state, the UE 1001 is registered with the network, and the UE context in AMF 1021 may hold a valid location or routing information for the UE 1001 so the UE 1001 is reachable by the AMF 1021. In the RM-REGISTERED state, the UE 1001 may perform mobility registration update procedures, perform periodic registration update procedures triggered by expiration of the periodic update timer (e.g., to notify the network that the UE 1001 is still active) , and perform a Registration Update procedure to update UE capability information or to re-negotiate protocol parameters with the network, among others.

The AMF 1021 may store one or more RM contexts for the UE 1001, where each RM context is associated with a specific access to the network. The RM context may be a data structure, database object, etc. that indicates or stores, inter glia, a registration state per access type and the periodic update timer. The AMF 1021 may also store a 5GC mobility management (MM) context that may be the same or similar to the evolved packet services (EPS) Mobility Management (E) MM context discussed previously. In various embodiments, the AMF 1021 may store a CE mode B Restriction parameter of the UE 1001 in an associated MM context or registration management (RM) context. The AMF 1021 may also derive the value, when needed, from the UE's usage setting parameter already stored in the UE context (and/or MM/RM context) .

Connection Management (CM) may be used to establish and release a signaling connection between the UE 1001 and the AMF 1021 over the N1 interface. The signaling connection is used to enable NAS signaling exchange between the UE 1001 and the CN 1020, and comprises both the signaling connection between the UE and the AN (e.g., RRC connection or UE-N3IWF connection for non-3GPP access) and the N2 connection for the UE 1001 between the AN (e.g., AN 1010) and the AMF 1021. The UE 1001 may operate in one of two CM states, CM-IDLE mode or CM-CONNECTED mode. When the UE 1001 is operating in the CM-IDLE state/mode, the UE 1001 may have no NAS signaling connection established with the AMF 1021 over the N1 interface, and there may be (R) AN 1010 signaling connection (e.g., N2 and/or N3 connections) for the UE 1001. When the UE 1001 is operating in the CM-CONNECTED state/mode, the UE 1001 may have an established NAS signaling connection with the AMF 1021 over the Nl interface, and there may be a (R) AN 1010 signaling connection (e.g., N2 and/or N3 connections) for the UE 1001. Establishment of an N2 connection between the (R) AN 1010 and the AMF 1021 may cause the UE 1001 to transition from CM-IDLE mode to CM-CONNECTED mode, and the UE 1001 may transition from the CM-CONNECTED mode to the CM-IDLE mode when N2 signaling between the (R) AN 1010 and the AMF 1021 is released.

The SMF 1024 may be responsible for session management (SM) session establishment, modify and release, including tunnel maintain between UPF and AN node) ; UE IP address allocation and management (including optional authorization) ; selection and control of UP function; configuring traffic steering at UPF to route traffic to proper destination; termination of interfaces toward policy control functions; controlling part of policy enforcement and QoS; lawful intercept (for SM events and interface to LI system) ; termination of SM parts of NAS messages; downlink data notification; initiating AN specific SM information, sent via AMF over N2 to AN; and determining SSC mode of a session. SM may refer to management of a PDU session, and a PDU session or "session" may refer to a PDU connectivity service that provides or enables the exchange of PDUs between a UE 1001 and a data network (DN) 1003 identified by a Data Network Name (DNN) . PDU sessions may be established upon UE 1001 request, modified upon UE 1001 and CN 1020 request, and released upon UE 1001 and CN 1020 request using NAS SM signaling exchanged over the N1 reference point between the UE 1001 and the SMF 1024. Upon request from an application server, the CN 1020 may trigger a specific application in the UE 1001. In response to receipt of the trigger message, the UE 1001 may pass the trigger message (or relevant parts/information of the trigger message) to one or more identified applications in the UE 1001. The identified application (s) in the UE 1001 may establish a PDU session to a specific data network name (DNN) . The SMF 1024 may check whether the UE 1001 requests are compliant with user subscription information associated with the UE 1001. In this regard, the SMF 1024 may retrieve and/or request to receive update notifications on SMF 1024 level subscription data from the UDM 1027.

The SMF 1024 may include the following roaming functionality: handling local enforcement to apply QoS SLAB virtual Public Land Mobile Network (VPLMN) ; charging data collection and charging interface (VPLMN) ; lawful intercept (in VPLMN for SM events and interface to LI system) ; and support for interaction with external DN for transport of signaling for PDU session authorization/authentication by external DN. An N16 reference point between two SMFs 1024 may be included in the system 1000, which may be between another SMF 1024 in a visited network and the SMF 1024 in the home network in roaming scenarios. Additionally, the SMF 1024 may exhibit the Nsmf service-based interface.

The NEF 1023 may provide means for securely exposing the services and capabilities provided by 3GPP network functions for third party, internal exposure/re-exposure, Application Functions (e.g., AF 1028) , edge computing or fog computing systems, etc. In such embodiments, the NEF 1023 may authenticate, authorize, and/or throttle the AFS. NEF 1023 may also translate information exchanged with the AF 1028 and information exchanged with internal network functions. For example, the NEF 1023 may translate between an AF-Service-Identifier and an internal SCC information. NEF 1023 may also receive information from other network functions (NFs) based on exposed capabilities of other network functions. This information may be stored at the NEF 1023 as structured data, or at a data storage NF using standardized interfaces. The stored information can then be re-exposed by the NEF 1023 to other NFs and AFs, and/or used for other purposes such as analytics. Additionally, the NEF 1023 may exhibit an Nnef service-based interface.

The NRF 1025 may support service discovery functions, receive NF discovery requests from NF instances, and provide the information of the discovered NF instances to the NF instances. NRF 1025 also maintains information of available NF instances and their supported services. As used herein, the terms "instantiate, " "instantiation, " and the like may refer to the creation of an instance, and an "instance" may refer to a concrete occurrence of an object, which may occur, for example, during execution of program code. Additionally, the NRF 1025 may exhibit the Nnrf service based interface.

The PCF 1026 may provide policy rules to control plane function (s) to enforce them, and may also support unified policy framework to govern network behavior, The PCF 1026 may also implement a front end (FE) to access subscription information relevant for policy decisions in a UDR of the UDM 1027. The PCF 1026 may communicate with the AMF 1021 via an N15 reference point between the PCF 1026 and the AMF 1021, which may include a PCF 1026 in a visited network and the AMF 1021 in case of roaming scenarios. The PCF 1026 may communicate with the AF 1028 via an NS reference point between the PCF 1026 and the AF 1028; and with the SMF 1024 via an N7 reference point between the PCF 1026 and the SMF 1024, The system 1000 and/or CN 1020 may also include an N24 reference point between the PCF 1026 (in the home network) and a PCF 1026 in a visited network, Additionally, the PCF 1026 may exhibit an Npcf service-based interface.

The UDM 1027 may handle subscription-related information to support the network entities' handling of communication sessions, and may store subscription data of UE 1001. For example, subscription data may be communicated between the UDM 1027 and the AMF 1021 via an NS reference point between the UDM 1027 and the AMF. The UDM 1027 may include two parts, an application FE and a UDR (the FE and UDR are not shown by FIG. 10) . The UDR may store subscription data and policy data for the UDM 1027 and the PCF 1026, and/or structured data for exposure and application data (including PFDs for application detection, application request information for multiple UEs 1001) for the NEF 1023. The Nadr service-based interface may be exhibited by the UDR 221 to allow the UDM 1027, PCF 1026, and NEF 1023 to access a particular set of the stored data, as well as to read, update (e.g., add, modify) , delete, and subscribe to notification of relevant data changes in the UDR. The UDM may include a UDM-FE, which is in charge of processing credentials, location management, subscription management and so on. Several different front ends may serve the same user in different transactions. The UDM-FE accesses subscription information stored in the UDR and performs authentication credential processing, user identification handling, access authorization, registration/mobility management, and subscription management. The UDR may interact with the SMF 1024 via an Nl0 reference point between the UDM 1027 and the SMF 1024. UDM 1027 may also support SMS management, wherein an SMS-FE implements the similar application logic as discussed previously. Additionally, the UDM 1027 may exhibit the Nudm service based interface.

The AF 1028 may provide application influence on traffic routing, provide access to the NCE, and interact with the policy framework for policy control. The NCE may be a mechanism that allows the CN 1020 and AF 1028 to provide information to each other via NEF 1023, which may be used for edge computing implementations. In such implementations, the network operator and third party services may be hosted close to the UE 1001 access point of attachment to achieve an efficient service delivery through the reduced end-to-end latency and load on the transport network. For edge computing implementations, the 5GC may select a UPF 1002 close to the UE 1001 and execute traffic steering from the UPF 502 to ON 1003 via the N6 interface. This may be based on the UE subscription data, UE location, and information provided by the AF 1028. In this way, the AF 1028 may influence UPF (re) selection and traffic routing. Based on operator deployment, when AF 1028 is considered to be a trusted entity, the network operator may permit AF 1028 to interact directly with relevant NFs. Additionally, the AF 1028 may exhibit an Naf service-based interface.

The NSSF 1029 may select a set of network slice instances serving the UE 501. The NSSF 1029 may also determine allowed Network Slice Selection Assistance Information (NSSAI) and the mapping to the subscribed single NSSAI (S-NSSAI) is, if needed. The NSSF 1029 may also determine the AMF set to be used to serve the UE 1001, or a list of candidate AMF (s) 1021 based on a suitable configuration and possibly by querying the NRF 1025. The selection of a set of network slice instances for the UE 1001 may be triggered by the AMF 1021 with which the UE 1001 is registered by interacting with the NSSF 1029, which may lead to a change of AMF 1021. The NSSF 1029 may interact with the AMF 1021 via an N22 reference point between AMF 1021 and NSSF 1029; and may communicate with another NSSF 1029 in a visited network via an N31 reference point (not shown by FIG. 10) . Additionally, the NSSF 1029 may exhibit an Nnssf service-based interface.

As discussed previously, the CN 1020 may include a short message service function (SMSF) , which may be responsible for SMS subscription checking and verification, and relaying SM messages to/from the UE 1001 to/from other entities, such as an SMS-GMSC/IWMSC/SMS-router. The SMS may also interact with AMF 1021 and UDM 1027 for a notification procedure that the UE 1001 is available for SMS transfer (e.g., set a UE not reachable flag, and notifying UDM 1027 when UE 1001 is available for SMS) .

The CN 1020 may also include other elements that are not shown by FIG. 10, such as a Data Storage system/architecture, a 5G-EIR, a Security Edge Protection Proxy (SEPP) , and the like. The Data Storage system may include a Structured Data Storage Network Function (SDSF) , air Unstructured Data Storage Function (UDSF) , and/or the like. Any network function (NF) may store and retrieve unstructured data into/from the UDSF (e.g., UE contexts) , via N18 reference point between any NF and the UDSF (not shown by FIG. 10) , Individual NFs may share a UDSF for storing their respective unstructured data or individual NFs may each have their own UDSF located at or near the individual NFs. Addition-ally, the UDSF may exhibit an Nudsf service-based interface (not shown by FIG. 10) . The 5G-EIR may be an NF that checks the status of permanent equipment identifier (PEI) for determining whether particular equipment/entities are blacklisted from the network; and the SEPP may be a non-transparent proxy that performs topology hiding, message filtering, and policing on inter-PLMN control plane interfaces.

Additionally, there may be many more reference points and/or service-based interfaces between the NF services in the NFs; however, these interfaces and reference points have been omitted from FIG. 10 for clarity. In one example, the CN 1020 may include an Nx interface, which is an inter-CN interface between a mobility management entity (MME) and the AMF 1021 in order to enable interworking between CN 1020 and a CN in a 4G system. Other example interfaces/reference points may include an N5G-EIR service-based interface exhibited by a 5G-EIR, an N27 reference point between the NRF in the visited network and the NRF in the home network; and an N31 reference point between the NSSF in the visited network and the NSSF in the home network.

Inter-CU Layer 2 Mobility (LTM)

In 3GPP Release 19, one objective is to specify support for inter-CU Layer1 (L1) /Layer2 (L2) -triggered mobility (LTM) . A case that may be desired to be supported is when the CU is acting as a master node (MN) when dual connectivity (DC) is not configured. Another case that may be desired to be supported is when new radio-DC (NR-DC) is configured and CU is acting as a Secondary Node (SN) and a Master Cell Group (MCG) is unchanged. Another case that may be desired to be supported is when NR-DC is configured, the CU is acting as MN and a secondary cell group (SCG) is unchanged or the SCG is released. The case that LTM is configured in both the MCG and the SCG may be excluded. 3GPP Rel-19 may specify support for subsequent LTM mobility procedures to avoid radio resource control (RRC) configuration between cell switches as per 3GPP Rel-18 LTM.

Measurement related enhancements for supporting LTM (RAN2, RAN1) may be applicable to Intra-CU MCG/SCG LTM and Inter-CU MCG/SCG LTM. Embodiments described herein disclose messaging used to identify distributed units (DUs) controlled by intra-CU or inter-CU, associating the DUs with an identifier, and communicating potential DUs that can be used for LTM to the UE as candidates for the UE to switch to during an LTM procedure.

Legacy Inter-CU handover security dynamics –For inter-CU (or even for intra-CU where a gNB intends a security context change) , a source gNB can provide the current UE security capabilities and security keys, e.g. KgNB (Kng-ran*) , to the target gNB. The KgNB can be derived from either: horizontal derivation -from the previous KgNB (when the source gNB does not have a NH/NCC pair) ; or vertical derivation -from the NH/NCC pair the source gNB has. The NCC can be provided to the target gNB. The source gNB can use the KgNB as the security key -derives the Kng-ran. The target gNB can use the Kng-ran as the KgNB key and can prepare the target configuration. The NCC used can also be included along with target configuration. The UE can derive the security keys based on the NCC. If the NCC is the same, then horizontal key derivation can be used. If the NCC is different, the UE can derive the NH until the NCC matches (with each increment) . After the handover is complete, the target gNB can inform the AMF with PATH SWITCH complete. The AMF can create a fresh set of NH/NCC and provide the target gNB.

Legacy L3 inter-CU handover may involve: the security key to be changed; the PDCP to be recovered and a new security context applied; the radio link control (RLC) to be reset; the old RLC context to be cleared and the RLC to start from an initial state; and the MAC to be reset for each transmit/receive point (TRP) . Even intra-CU allows a security key “refresh” , which results in a security context change and so the associated PDCP recovery/RLC and MAC Reset.

FIG. 11: Deployment via Xn

FIG. 11 provides an example diagram of intra-CU and inter-CU LTM cell switching 1100, according to some embodiments. There may be a mix of intra-CU and inter-CU physical cell identities (PCIs) when viewed from the UE perspective. From the UE perspective, the UE can see cells (PCI) from a same (intra) or a different (inter) CU. One CU-m can interface with another CU-n via an Xn interface 1110. The Xn interface 1110 can be a point-to-point interface between two Next Generation Radio Access Network (NG-RAN) nodes.

FIG. 12: Deployment via Ng

FIG. 12 provides an example diagram of intra-CU and inter-CU LTM cell switching 1200, according to some embodiments. Again, there may be a mix of intra and inter-CU physical cell identities (PCIs) when viewed from the UE perspective. The CU-m can interface with another CU-n via an Access & Mobility Management Function (AMF) 1210 in the core network 1020 (FIG. 10) over an Ng interface. The AMF 1210 can be a control plane function in the 5G core network that handles connection and management mobility tasks. Each CU can be connected to one or more DUs via an F1 interface. Each DU can have one or more PCIs.

For intra-CU LTM, the gNB-CU (e.g. source CU) can act as the coordinator. The gNB-CU can obtain candidate PCIs information from the DUs, e.g. using a UE_CONTEXT_SETUP_REQUEST/RESPONSE message. The gNB-CU can provide the “assorted” configuration to the source DU, e.g. using a UE_CONTEXT_MODIFICATION_REQUEST/RESPONSE message. The gNB-CU can consolidate the net “RRC” configuration and then provide the configuration to the UE using a source DU, e.g. using a DL RRC MESSAGE TRANSFER message. For inter-CU, a central coordinator may also be needed.

The physical layer configuration can be “shielded” under a gNB-CU. Beam, channel state information (CSI) , and other physical layer information may not be shared outside of a CU in a legacy operation. The Xn HANDOVER_REQUEST/ACK message may be used only to exchange UE specific context information.

The LTM configuration can handle design solutions for inter-CU LTM at the network node exchange and how the UE would be configured. The UE behavior during an LTM switch can be based on a prior RRC configuration and the presence/absence of an LTM switch MAC CE during LTM (inter-CU) . However, additional UE behavior during an LTM switch may be obtained through additional signaling. For example, a determination is needed how the UE will know whether the LTM switch is intra-DU or inter-DU; or intra-CU or inter-CU. Additional signaling can clarify the UE behavior during LTM switching.

FIG. 13: Uniform Interface Towards UE

FIG. 13 illustrates an example of signaling 1300 for inter-CU LTM switching, according to some embodiments. The UE 106 can be provided with a candidate set of LTM cells where the candidate set of LTM cells are provided as a list to the UE 106. In a step 1: a source central unit (CU) can determine which target or candidate CUs (CU1, CU2) are useful for the UE 106.

In a step 2: the source CU can obtain the LTM configuration information from these candidate CUs (CU1, CU2) . In one aspect, the source CU can use a HANDOVER_REQUEST message to trigger a request for the LTM configuration information. In another aspect, each candidate CU (CU1, CU2) can request the target or candidate distributed units (DUs) (DU10, DU11, DU20) that each respective CU controls for the information on the candidate DUs. The candidate CUs (CU1, CU2) can determine which DUs from which to request information. The candidate CUs (CU1, CU2) can use the UE CONTEXT_SETUP_REQUEST/RESPONSE message to request and/or collect the candidate DU (DU10, DU11, DU20) configuration information. In another aspect, each candidate CU (CU1, CU2) can compose a net configuration as a list of candidate DUs (DU10, DU11, DU20) . In another aspect, each candidate CU (CU1, CU2) can respond back to the source CU in a HANDOVER_REQUEST_ACKNOWLEDGE with the list of candidate or target DUs (DU10, DU11, DU20) coupled the candidate CU (CU1, CU2) .

In a step 3: the source CU can order the list of candidate cells of the target or candidate DU (DU10, DU11, DU20) from each of the candidate CUs (CU1, CU2) . The source CU can assign a candidate cell index and can ensure that there is no repetition of the indices across the candidate DUs (DU10, DU11, DU20) from all the candidate CUs (CU1, CU2) .

In a step 4: the source CU can inform the source DU about the list of candidate cells and the candidate cell index using a UE_CONTEXT_MODIFICATION procedure.

In a step 5: The source CU can prepare an RRC message with the configuration of LTM candidates and send the RRC message to the UE 106 via the source DU using a DL RRC MESSAGE TRANSFER message. The source CU can receive a confirmation from the source DU that the RRC message to the UE was sent.

In some examples, an apparatus of a next generation Node B (gNB) 102 can comprise one or more processors 204, coupled to a memory 260. The processors 204 can be configured to determine, at a source centralized unit (CU) of the gNB 102, one or more candidate CUs (CU1, CU2) for a user equipment (UE) 106. The processors 204 can be configured to send a handover request from the source CU of the gNB 102 to the one or more candidate CUs (CU1, CU2) . The processors 204 can be configured to receive handover request acknowledgements from the one or more candidate CUs (CU1, CU2) at the source CU of the gNB 102 with information regarding candidate distributed units (DUs) coupled to each of the one or more candidate CUs, to form a list of candidate DUs (DU10, DU11, DU20) . The processors 204 can be configured to assign, at the source CU of the gNB 102, indices for the candidate DUs (DU10, DU11, DU20) coupled to the one or more candidate CUs (CU1, CU2) . The processors 204 can be configured to encode, at the source CU of the gNB 102, a radio resource control (RRC) message with the list of candidate DUs (DU10, DU11, DU20) coupled to the one or more candidate CUs (CU1, CU2) and the assigned indices for transmission to the UE 106 via a source DU of the gNB 102. In one example, the RRC message can be a DL RRC MESSAGE TRANSFER message. However, other types of RRC messages may also be used to communicate the list of candidate DUs and assigned indices to the UE.

In another aspect, the one or more candidate CUs (CU1, CU2) can comprise inter-CUs.

In another aspect, the processors 204 can be configured to order, at the source CU of the gNB 102, the list of candidate DUs (DU10, DU11, DU20) coupled to the one or more candidate CUs (CU1, CU2) .

In another aspect, the processors 204 can be configured to send the list of candidate DUs (DU10, DU11, DU20) coupled to the one or more candidate CUs (CU1, CU2) and the assigned indices from the source CU of the gNB 102 to the source DU of the gNB 102. The processors 204 can be configured to send the assigned indices for the candidate DUs (DU10, DU11, DU20) coupled to the one or more candidate CUs (CU1, CU2) and the assigned indices from the source CU of the gNB 102 to the source DU of the gNB 102 using a UE context modification (UE_CONTEXT_MODIFICATION) procedure. The processors 204 can be configured to receive, at the source CU of the gNB 102, confirmation from the source DU that the list of candidate DUs (DU10, DU11, DU20) and the assigned indices were communicated to the UE.

In another aspect, the processors 204 can be configured to send the handover requests and receive the handover request acknowledgements via an Xn interface 1110 between the source CU and the one or more candidate CUs (CU1, CU2) .

In another aspect, the processors 204 can be configured to receive the handover request acknowledgements from the one or more candidate CUs (CU1, CU2) at the source CU of the gNB 102. At least one candidate CU in the one or more candidate CUs can be configured to: send a request, in a UE context setup request (UE CONTEXT_SETUP_REQUEST) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs (DU10, DU11, DU20) that are controlled by the at least one candidate CU; or send the request for LTM information to selected DUs (DU10, DU11, DU20) that are controlled by the at least one candidate CU; and send a list of candidate DUs (DU10, DU11, DU20) with the LTM information to the source CU in a handover request acknowledgement (HANDOVER_REQUEST_ACKNOWLEDGEMENT) message.

FIG. 14: Flow Chart for a Method of Inter-CU LTM

FIG. 14 illustrates a flow chart of an example of a method 1400 for inter-central unit (CU) Layer1/Layer2-triggered mobility (LTM) , according to some embodiments. The method shown in FIG. 14 may be used in conjunction with any of the systems, methods, or devices illustrated in the Figures, among other devices. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

In accordance with an embodiment, a method 1400 for inter-central unit (CU) Layer1/Layer2-triggered mobility (LTM) at a next generation Node B (gNB) is disclosed. The method 1400 can comprise determining 1410, at a source CU of the gNB, one or more candidate CUs for a user equipment (UE) . The method 1400 can comprise sending 1420 a handover request from the source CU of the gNB to the one or more candidate CUs. The method 1400 can comprise receiving 1430 handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB with information regarding candidate distributed units (DUs) coupled to the one or more candidate CUs, to form a list of candidate DUs. The method 1400 can comprise assigning 1440, at the source CU of the gNB, indices for the candidate DUs coupled to the one or more candidate CUs. The method 1400 can comprise encoding 1450, at the source CU of the gNB, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU of the gNB.

In another aspect, the method 1400 can further comprise the one or more candidate CUs comprising inter-CUs.

In another aspect, the method 1400 can further comprise ordering, at the source CU of the gNB, the list of candidate DUs coupled to the one or more candidate CUs.

In another aspect, the method 1400 can further comprise sending the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices from the source CU of the gNB to the source DU of the gNB. The method 1400 can further comprise sending the assigned indices for the candidate DUs coupled to the one or more candidate CUs and the assigned indices from the source CU of the gNB to the source DU of the gNB using a UE context modification (UE_CONTEXT_MODIFICATION) procedure. The method 1400 can further comprise receiving, at the source CU of the gNB, confirmation from the source DU of the list of candidate DUs and the assigned indices communication to the UE.

In another aspect, the method 1400 can further comprise sending the handover requests and receiving the handover request acknowledgements via an Xn interface between the source CU and the one or more candidate CUs. The method 1400 can further comprise receiving the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB. At least one candidate CU in the one or more candidate CUs is configured to:send a request, in a UE context setup request (UE CONTEXT_SETUP_REQUEST) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs that are controlled by the at least one candidate CU; or send the request for LTM information to selected DUs that are controlled by the at least one candidate CU; and send a list of candidate DUs with the LTM information to the source CU in a handover request acknowledgement (HANDOVER_REQUEST_ACKNOWLEDGEMENT) message.

FIG. 15: Uniform Interface Towards UE with NG

FIG. 15 illustrates an example of signaling 1500 for inter-CU LTM switching, according to some embodiments. The UE 106 can be provided with a candidate set of LTM cells where the candidate set of LTM cells is provided as a list to the UE 106. In a step 1: a source CU can determine which candidate CUs (CU1, CU2) are useful for the UE 106.

In a step 2: the source CU can obtain the LTM configuration information from these target or candidate CUs (CU2) using an AMF (AMF2) via an Ng interface. In another aspect, the source CU can use an NG CONTEXT MODIFICATION message to trigger a request for the LTM configuration information. In another aspect, the AMF (AMF2) can request the LTM candidates from each candidate CU (CU2) using an NG CONTEXT MODIFICATION message. In another aspect, each candidate CU (CU2) can request the DUs (DU20) it controls for the information on the target or candidate DUs (DU20) . The candidate CU (CU2) can determine which DUs (DU20) from which to request information. The candidate CU (CU2) can use a UE CONTEXT_SETUP_REQUEST/RESPONSE message to request and/or collect the DU configuration information. In another aspect, each candidate CU (CU2) can compose a net configuration as a list of DUs (DU20) controlled by the candidate CU.In another aspect, each candidate CU (CU2) can respond back to the source CU in an NG CONTEXT MODIFICATION ACK message with the list of candidate DUs (CU20) controlled by the candidate CU (CU2) .

In a step 3: the source CU can order the list of candidate cells from the candidate DUs (DU10, DU11, DU20) from each of the candidate CUs (CU1, CU2) . In another aspect, the source CU can assign each DU a candidate cell index and can ensure that there is no repetition of the indices across the DUs (DU10, DU11, DU20) from all of the candidate CUs (CU1, CU2) .

In a step 5: the source CU can receive a confirmation from the source DU that the procedure was successful. The source CU can prepare an RRC message with a configuration of the LTM candidates and can send the RRC message to the UE 106 via the source DU using a DL RRC MESSAGE TRANSFER message.

The UE 106 can determine the NCC, as opposed to having an AMF determine the NCC. The UE selection of the NCC allows all three actors: i.e. the UE, the gNB and the AMF to be in sync with the next key to be used. The gNBs may still not be able to know the NH of other gNBs so that security requirements are maintained. An interface change may be required between the gNB and the AMF (N2 interface) , and the gNB-gNB (Xn interface) , along with RRC changes in the UE interface.

In some examples, the processors 204 can be further configured to send the handover requests and receive the handover request acknowledgements via Ng interfaces between each CU (CU2) and an access and mobility management function (AMF) of a network. The processors 204 can be further configured to receive the handover request acknowledgements from the one or more candidate CUs (CU2) at the source CU of the gNB 102. The AMF (AMF2) can be configured to send a request, in an Ng context modification (NG CONTEXT MODIFICATION) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information to each candidate CU (CU2) . The processors 204 can be further configured to receive the handover request acknowledgements from the one or more candidate CUs (CU2) at the source CU of the gNB 102. At least one candidate CU (CU2) in the one or more candidate CUs can be configured to: send a request, in a UE context setup request/response (UE CONTEXT_SETUP_REQUEST/RESPONSE) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the one or more candidate DUs (DU20) that are controlled by the at least one candidate CU (CU2) ; or send the request for LTM information to selected DUs (DU20) that are controlled by the at least one candidate CU (CU2) ; and send a list of candidate DUs (DU20) with the LTM information to the source CU in an Ng context modification acknowledgement (NG CONTEXT MODIFICATION ACKNOWLEDGEMENT) message.

In some examples, the method 1400 can further comprise sending the handover requests and receiving the handover request acknowledgements via Ng interfaces between each CU an access and mobility management function (AMF) of a network. The method 1400 can further comprise receiving the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB. The AMF can be configured to send a request, in an Ng context modification (NG CONTEXT MODIFICATION) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information to each candidate CU. The method 1400 can further comprise receiving the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB. At least one candidate CU in the one or more candidate CUs can be configured to: send a request, in a UE context setup request/response (UE CONTEXT_SETUP_REQUEST/RESPONSE) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs that are controlled by the at least one candidate CU; or send the request for LTM information to selected DUs that are controlled by the at least one candidate CU; and send a list of candidate DUs with the LTM information to the source CU in an NG context modification acknowledgement (NG CONTEXT MODIFICATION ACKNOWLEDGEMENT) message.

FIGs. 16 and 17: Uniform Interface Towards UE at the UE

FIGs. 16 and 17 illustrate examples of MAC CEs 1600 and 1700 for sending information, according to some embodiments. The UE can store the candidate cells as a list. The UE may not differentiate between candidate cells (e.g. DUs) controlled by inter-CU and candidate cells controlled by intra-CU.

A network node may transmit the MAC CE 1600 or 1700 to a UE. The UE can obtain information from the MAC CE 1600 or 1700. The MAC CE 1600 or 1700 can include a MAC CE type indication field 1604. The MAC CE type indication field 1604 can indicate the type of the MAC CE. In the illustrated example, the MAC CE type indication field 1604 indicates that the MAC CE 1600 or 1700 is for an LTM cell switch. Accordingly, the UE can use the information in the MAC CE 1600 or 1700 to prepare for the LTM cell switch. For example, the MAC CE 1600 or 1700 can include a candidate cell configuration field 1606. The candidate cell configuration field 1606 can indicate the target cell that the UE should switch to. The MAC CE 1600 or 1700 can also include other information such as a transmission configuration indicator (TCI) configuration field 1608 that includes TCI configuration information.

Referring to FIG. 16, when there is an LTM cell switch, the MAC CE 1600 can provide the information on whether the cell switch is inter-CU or intra-CU. For example, the MAC CE 1600 can include an Inter-CU LTM information field 1612. In the absence of MAC CE information on the inter-CU, the UE may follow 3GPP Rel-18 logic of doing a radio link control (RLC) reset or only a MAC reset.

In some examples, the processors 204 can be configured to encode, at the source DU of the gNB 102, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU indication or an intra-CU indication.

In some examples, the method 1400 can further comprise encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU indication or an intra-CU indication.

Referring to FIG. 17, the MAC CE 1700 can include an additional index to carry information related to a next hop chaining counter (nextHopChainingCount) (NCC) . For example, the MAC CE 1700 can include an Inter-CU LTM NCC information field 1712. The presence of an NCC in the MAC CE 1700 indicates that it is an inter-CU cell switch. No new field may be needed. The presence of the NCC (which may be used for security context change) , may now also imply that it is an inter-CU cell switch. In the absence of a MAC CE NCC, the UE may follow 3GPP Rel-18 logic of doing an RLC reset or only a MAC reset. The MAC CE 1700 may also include other information such as a random access channel (RACH) configuration field 1710 that includes RACH configuration information.

In some examples, the processors 204 can be configured to encode, at the source DU of the gNB 102, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with a Next Hop parameter (NH) NH Chaining Counter (NCC) indicating an inter-CU cell switch.

In some examples, the method 1400 can further comprise encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with a Next Hop parameter (NH) NH Chaining Counter (NCC) indicating an inter-CU cell switch.

In either case above, the UE can re-establish the PDCP context (i.e. perform a PDCP recovery) and can reset the RLC and the MAC.

FIG. 18: Handling at per-CU Basis

FIG. 18 illustrates an example of signaling 1800 for inter-CU LTM switching, according to some embodiments. The handling may be on a per CU basis. In certain situations, such as inter-vendor CU cases, the gNB-CU may not be exposed to the configuration aspects of DUs that are controlled by the target/candidate CUs. In a step 1: the source CU can determine which candidate CUs are useful for the UE.

In a step 2: the source CU can obtain the LTM configuration information from these candidate CUs. In one aspect, the source CU can use a HANDOVER_REQUEST message to trigger a request for the LTM configuration information. In another aspect, each candidate CU can request the DUs it controls for information on the candidate DUs. The candidate CU can determine which DUs from which to request information. The candidate CU can use the UE CONTEXT_SETUP_REQUEST/RESPONSE message to request and/or collect the DU configuration. In another aspect, each candidate CU can compose a net configuration as a list of DUs. In another aspect, each candidate CU can respond back to the source CU in a HANDOVER_REQUEST_ACKNOWLEDGE with the list of candidate DUs controlled by the candidate CU.

In a step 3, the source CU can order the list of candidate cells where each DU is within its CU container. In another aspect, the source CU can assign the candidate cell index, but the candidate cell indices are coupled to each CU. The source CU can ensure that there is no repetition of the indices within the DUs from each candidate CU; but across the candidate CUs there may be no such restriction. In another aspect, the source CU can assign an index to each CU.

In a step 4: the source CU can inform the source DU about the list of candidate cells and the candidate cell indices, e.g. using a UE_CONTEXT_MODIFICATION procedure.

In a step 5: the source CU can receive a confirmation from the source DU. The source CU can prepare an RRC message with the configuration of the LTM candidates and can send the RRC message to the UE via the source DU using a DL RRC MESSAGE TRANSFER message.

In some examples, the processors 204 can be configured to order, at the source CU of the gNB 102, the list of candidate DUs coupled to the one or more candidate CUs within a corresponding CU container. The processors 204 can be configured to assign, at the source CU of the gNB 102, the indices for the one or more candidate DUs coupled to the one or more candidate CUs within the corresponding CU container. The processors 204 can be configured to assign, at the source CU of the gNB 102, indices for the one or more candidate CUs.

In some examples, the method 1400 can further comprise ordering, at the source CU of the gNB, the list of candidate DUs coupled to the one or more candidate CUs within a corresponding CU container. The method 1400 can further comprise assigning, at the source CU of the gNB, the indices for the one or more candidate DUs coupled to the candidate CUs within the corresponding CU container. The method can further comprise assigning, at the source CU of the gNB, indices for the one or more candidate CUs.

FIG. 19: Handling at per-CU Basis

FIG. 19 illustrates an example of a MAC CE 1900 for sending information, according to some embodiments. This approach may be the same as when an AMF (Ng interface) is involved. The UE can store the candidate cells as a list; but the UE may maintain the list per candidate CU. The UE differentiation between intra-DU and inter-DU within the CU container may follow Rel-18 logic.

For LTM switches across the CUs, when there is an LTM cell switch, the MAC CE can provide the information on whether it is an inter-CU or intra-CU cell switch with the CU index. For example, the MAC CE 1600 can include an Inter-CU LTM information field 1912. In the absence of MAC CE information on inter-CU, the UE can follow 3GPP Rel-18 logic of performing an RLC reset or only a MAC reset. If, however, the MAC CE does not indicate inter-CU, then the LTM candidate cell index is assumed to be within a CU, or intra-CU, because the index can be the same across CUs. Otherwise, the MAC CE can indicate the CU container index. The UE can re-establish a packet data convergence protocol (PDCP) context (i.e. perform a PDCP recovery) and can reset the RLC and the MAC.

In some examples, the processors 204 can be configured to encode, at the source DU of the gNB 102, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU with a CU index or intra-CU indication.

In some examples, the method 1400 can comprise encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU with a CU index or an intra-CU indication.

FIGs. 20 and 21: Hybrid Approach per-CU Basis

According to some examples of per-CU basis, the UE can be provided with a list of candidate LTM cells where the index of the cells includes information of the parent CU. The UE can store the candidate cells as a list and may not differentiate between CUs, but each candidate DU can be associated with information of its parent CU.

In some examples, the processors 204 can be configured to assign, at the source CU of the gNB, the indices for the candidate DUs coupled to the one or more candidate CUs with information on a corresponding candidate CU.

In some examples, the method 1400 can further comprise assigning, at the source CU of the gNB, the indices for the candidate DUs coupled to the one or more candidate CUs with information on a corresponding candidate CU.

According to some examples, all of the cells can have a unique index, even when the parent CU is present. For an LTM switch, based on the index of the candidate cell in the LTM cell switch MAC CE, the UE can derive if it is inter-CU or intra-CU. The CU index in MAC CE may not be required.

FIG. 20 illustrates an example of ASN. 1 code 2000 used for the network to configure the SIB1, according to some embodiments. There may be no change to the MAC CE LTM structure. A field or information element (IE) may be introduced, such as an ltm-parentCU-Index-r19. The index can provide the number of LTM CU for UEs configured for 3GPP Release 19 (r19) .

In some examples, all of the one or more candidate DUs can have a unique index.

FIG. 21 illustrates an example of a MAC CE 2100 for sending information, according to some embodiments. According to some examples of per-CU basis, the UE can be provided with a list of candidate LTM cells where the index of the cells includes information of the parent CU. The UE can store the candidate cells as a list and may not differentiate between CUs, but each candidate DU can have information of its parent CU.

According to some examples, all of the cells may not have unique indices across the CUs, as described herein, even when the parent CU is present. For an LTM switch, the LTM MAC CE can include the parent CU index as well. Each CU may re-use the same index within the candidate cells within it, and the UE can differentiate as the MAC CE would have the CU index, and the CU index provides the context for which DU within this CU. For example, the MAC CE 1600 can include an Inter-CU LTM information field 2112. Based on the index of the CU (or the presence of the CU index) in the LTM cell switch MAC CE, the UE can derive if it is an inter-CU or an intra-CU cell switch. If the index of CU is absent, then the LTM candidate cell index may belong to the current CU. According to some examples, the LTM-CandidateId-r18 may not be unique and may be linked with ltm-parentCU-Index-r19.

In some examples, the processors 204 can further be configured to encode, at the source DU of the gNB 102, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with an inter-CU with a CU index. In another aspect, the CU index can further comprise an LTM parent CU index (ltm-parentCU-r19) .

In some examples, the method 1400 can further comprise encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with an inter-CU with a CU index. In another aspect, the CU index can further comprise an LTM parent CU index (ltm-parentCU-r19) .

FIG. 22: UE Triggered LTM Without LTM MAC CE

FIG. 22 illustrates an example of LTM switches 2200, according to some embodiments. According to some examples, unique indices as described herein can be used where the UE is configured with the parent CU also as described herein. The CU index may not be used in an LTM MAC CE and there may be no LTM MAC CE. The UE can store the candidate cells as a list and may not differentiate between inter-CU and intra-CU. An LTM switch may be triggered by the UE (without a MAC CE) . If the index of the source LTM candidate and the target LTM candidate results in a change of the CU index, then the UE can assume inter-CU LTM. Otherwise, it is intra-CU LTM. If it is inter-CU (as derived by above logic) , then the UE can use the next set of security keys.

Examples of LTM switches can include: 4 to 1 (for inter-CU) ; 4 to 2 (for intra-CU) ; any switch from 6 can be inter-CU (because only 6 is a candidate in the CU with ID 4) ; and similarly with ID 1 (CU ID is 7) .

Embodiments of the present disclosure may be realized in any of various forms. For example, some embodiments may be realized as a computer-implemented method, a computer readable memory medium, or a computer system. Other embodiments may be realized using one or more custom-designed hardware devices such as ASICs. Still other embodiments may be realized using one or more programmable hardware elements such as FPGAs.

In some embodiments, a non-transitory computer-readable memory medium may be configured so that it stores program instructions and/or data, where the program instructions, if executed by a computer system, cause the computer system to perform a method, e.g., any of the method embodiments described herein, or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106) may be configured to include a processor (or a set of processors) and a memory medium, where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, where the program instructions are executable to implement any of the various method embodiments described herein (or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets) . The device may be realized in any of various forms.

Any of the methods described herein for operating a user equipment (UE) may be the basis of a corresponding method for operating a base station, by interpreting each message/signal X received by the UE in the downlink as message/signal X transmitted by the base station, and each message/signal Y transmitted in the uplink by the UE as a message/signal Y received by the base station.

Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

Claims

An apparatus of a next generation Node B (gNB) comprising:

one or more processors, coupled to a memory, configured to:

determine, at a source centralized unit (CU) of the gNB, one or more candidate CUs for a user equipment (UE) ;

send a handover request from the source CU of the gNB to the one or more candidate CUs;

receive handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB with information regarding candidate distributed units (DUs) coupled to the one or more candidate CUs, to form a list of candidate DUs;

assign, at the source CU of the gNB, indices for the candidate DUs coupled to the one or more candidate CUs; and

encode, at the source CU of the gNB, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU of the gNB.
The apparatus of claim 1, wherein the one or more candidate CUs comprise inter-CUs.
The apparatus of claim 1, wherein the one or more processors are further configured to:

order, at the source CU of the gNB, the list of candidate DUs coupled to the one or more candidate CUs.
The apparatus of claim 1, wherein the one or more processors are further configured to:

send the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices from the source CU of the gNB to the source DU of the gNB.
The apparatus of claim 4, wherein the one or more processors are further configured to:

send the assigned indices for the candidate DUs coupled to the one or more candidate CUs and the assigned indices from the source CU of the gNB to the source DU of the gNB using a UE context modification (UE_CONTEXT_MODIFICATION) procedure.
The apparatus of claim 4, wherein the one or more processors are further configured to:

receive, at the source CU of the gNB, confirmation from the source DU that the list of candidate DUs and the assigned indices were communicated to the UE.
The apparatus of claim 1, wherein the one or more processors are further configured to:

send the handover requests and receive the handover request acknowledgements via an Xn interface between the source CU and the one or more candidate CUs.
The apparatus of claim 7, wherein the one or more processors are further configured to:

receive the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB, wherein at least one candidate CU in the one or more candidate CUs is configured to:

send a request, in a UE context setup request (UE CONTEXT_SETUP_REQUEST) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs that are controlled by the at least one candidate CU; or

send the request for LTM information to selected DUs that are controlled by the at least one candidate CU; and

send a list of candidate DUs with the LTM information to the source CU in a handover request acknowledgement (HANDOVER_REQUEST_ACKNOWLEDGEMENT) message.
The apparatus of claim 1, wherein the one or more processors are further configured to:

send the handover requests and receive the handover request acknowledgements via NG interfaces between each CU and an access and mobility management function (AMF) of a network.
The apparatus of claim 9, wherein the one or more processors are further configured to:

receive the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB, wherein the AMF is configured to:

send a request, in an NG context modification (NG CONTEXT MODIFICATION) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information to each candidate CU.
The apparatus of claim 10, wherein the one or more processors are further configured to:

receive the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB, wherein at least one candidate CU in the one or more candidate CUs is configured to:

send a request, in a UE context setup request/response (UE CONTEXT_SETUP_REQUEST/RESPONSE) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs that are controlled by the at least one candidate CU; or

send the request for LTM information to selected DUs that are controlled by the at least one candidate CU; and

send a list of candidate DUs with the LTM information to the source CU in an NG context modification acknowledgement (NG CONTEXT MODIFICATION ACKNOWLEDGEMENT) message.
The apparatus of claim 1, wherein the one or more processors are further configured to:

encode, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU indication or an intra-CU indication.
The apparatus of claim 1, wherein the one or more processors are further configured to:

encode, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with a Next Hop parameter (NH) NH Chaining Counter (NCC) indicating an inter-CU.
The apparatus of claim 1, wherein the one or more processors are further configured to:

order, at the source CU of the gNB, the list of candidate DUs coupled to the one or more candidate CUs within a corresponding CU container;

assign, at the source CU of the gNB, the indices for the candidate DUs coupled to the one or more candidate CUs within the corresponding CU container; and

assign, at the source CU of the gNB, indices for the one or more candidate CUs.
The apparatus of claim 14, wherein the one or more processors are further configured to:

encode, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU with a CU index or intra-CU indication.
The apparatus of claim 1, wherein the one or more processors are further configured to:

assign, at the source CU of the gNB, the indices for the candidate DUs coupled to the one or more candidate CUs with information on a corresponding candidate CU.
The apparatus of claim 16, wherein all the candidate DUs have a unique index.
The apparatus of claim 16, wherein the one or more processors are further configured to:

encode, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with an inter-CU with a CU index.
The apparatus of claim 18, wherein the CU index further comprises an LTM parent CU index (ltm-parentCU-r19) .
A method of inter-central unit (CU) Layer1/Layer2-triggered mobility (LTM) at a next generation Node B (gNB) , the method comprising:

determining, at a source CU of the gNB, one or more candidate CUs for a user equipment (UE) ;

sending a handover request from the source CU of the gNB to the one or more candidate CUs;

receiving handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB with information regarding candidate distributed units (DUs) coupled to the one or more candidate CUs, to form a list of candidate DUs;

assigning, at the source CU of the gNB, indices for the candidate DUs coupled to the one or more candidate CUs; and

encoding, at the source CU of the gNB, a radio resource control (RRC) message with the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices for transmission to the UE via a source DU of the gNB.
The method of claim 20, wherein the one or more candidate CUs comprise inter-CUs.
The method of claim 20, further comprising:

ordering, at the source CU of the gNB, the list of candidate DUs coupled to the one or more candidate CUs.
The method of claim 20, further comprising:

sending the list of candidate DUs coupled to the one or more candidate CUs and the assigned indices from the source CU of the gNB to the source DU of the gNB.
The method of claim 23, further comprising:

sending the assigned indices for the candidate DUs coupled to the one or more candidate CUs and the assigned indices from the source CU of the gNB to the source DU of the gNB using a UE context modification (UE_CONTEXT_MODIFICATION) procedure.
The method of claim 23, further comprising:

receiving, at the source CU of the gNB, confirmation from the source DU that the list of candidate DUs and the assigned indices were communicated to the UE.
The method of claim 20, further comprising:

sending the handover requests and receive the handover request acknowledgements via an Xn interface between the source CU and the one or more candidate CUs.
The method of claim 26, further comprising:

receiving the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB, wherein at least one candidate CU in the one or more candidate CUs is configured to:

send a request, in a UE context setup request (UE CONTEXT_SETUP_REQUEST) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs that are controlled by the at least one candidate CU; or

send the request for LTM information to selected DUs that are controlled by the at least one candidate CU; and

send a list of candidate DUs with the LTM information to the source CU in a handover request acknowledgement (HANDOVER_REQUEST_ACKNOWLEDGEMENT) message.
The method of claim 20, further comprising:

sending the handover requests and receiving the handover request acknowledgements via NG interfaces between each CU and an access and mobility management function (AMF) of a network.
The method of claim 28, further comprising:

receiving the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB, wherein the AMF is configured to:

sending a request, in an NG context modification (NG CONTEXT MODIFICATION) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information to each candidate CU.
The method of claim 29, further comprising:

receiving the handover request acknowledgements from the one or more candidate CUs at the source CU of the gNB, wherein at least one candidate CU in the one or more candidate CUs is configured to:

send a request, in a UE context setup request/response (UE CONTEXT_SETUP_REQUEST/RESPONSE) message, for Layer 1/Layer 2 Triggered Mobility (LTM) information from each of the candidate DUs that are controlled by the at least one candidate CU; or

send the request for LTM information to selected DUs that are controlled by the at least one candidate CU; and

send a list of candidate DUs with the LTM information to the source CU in an NG context modification acknowledgement (NG CONTEXT MODIFICATION ACKNOWLEDGEMENT) message.
The method of claim 20, further comprising:

encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU indication or an intra-CU indication.
The method of claim 20, further comprising:

encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with a Next Hop parameter (NH) NH Chaining Counter (NCC) indicating an inter-CU.
The method of claim 20, further comprising:

ordering, at the source CU of the gNB, the list of candidate DUs coupled to the one or more candidate CUs within a corresponding CU container;

assigning, at the source CU of the gNB, the indices for the candidate DUs coupled to the one or more candidate CUs within the corresponding CU container; and

assigning, at the source CU of the gNB, indices for the one or more candidate CUs.
The method of claim 33, further comprising:

encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with either an inter-CU with a CU index or intra-CU indication.
The method of claim 20, further comprising:

assigning, at the source CU of the gNB, the indices for the candidate DUs coupled to the one or more candidate CUs with information on a corresponding candidate CU.
The method of claim 35, wherein all the candidate DUs have a unique index.
The method of claim 35, further comprising:

encoding, at the source DU of the gNB, a medium access control –control element (MAC CE) indicating a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch with an inter-CU with a CU index.
The method of claim 37, wherein the CU index further comprises an LTM parent CU index (ltm-parentCU-r19) .
An apparatus configured to cause a next generation node B (gNB) to perform any of the methods of claims 20 to 38.
A next generation node B (gNB) configured to perform any of the operations described herein.
A computer program product, comprising computer instructions which, when executed by one or more processors, perform any of the operations described herein.