Mac level configuration for lower layer cell change

Abstract

Example embodiments of the present disclosure relate to methods, apparatuses, and a computer readable storage medium for enabling lower layer mobility. In some embodiments, the present disclosure may enable lower layer configurations to be provided from a distributed apparatus to a user equipment directly. In some embodiments, the present disclosure may enable lower layer configurations to be provided from the distributed apparatus to the user equipment indirectly using a container and via a central apparatus. The present disclosure provides the lower layer configurations with associations between resource configurations and measurement report configurations that can be individually referenced and / or updated by the distributed apparatus as needed.

Description

[0001] MAC LEVEL CONFIGURATION FOR LOWER LAYER CELL CHANGE

[0002] FIELD:

[0003] Example embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods, apparatuses, and computer readable storage media for performing distributed configuration signaling within a wireless network environment.

[0004] BACKGROUND:

[0005] Examples of mobile or wireless telecommunication systems may include the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), MulteFire, LTE-A Pro, fifth generation (5G) radio access technology or new radio (NR) access technology, sixth generation (6G) radio access technology, and / or beyond.

[0006] With respect to 5G, network enhancements were driven with respect to latency, throughput, and spectral efficiency. With the advent of 6G and beyond, network enhancements may be pushed even further, so there is a need to facilitate gains in network performance.

[0007] SUMMARY:

[0008] According to a first embodiment, a central apparatus of a network node is provided. The central apparatus may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the central apparatus at least to receive, from a user equipment, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus of the network node; and transmit, to the distributed apparatus, an indication that the user equipment is connected to the serving cell of the distributed apparatus.

[0009] According to a second embodiment, a distributed apparatus of a network node is provided. The distributed apparatus may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the distributed apparatus at least to receive, from a central apparatus of the network node, an indication that a user equipment is connected to a serving cell of the distributed apparatus; transmit, to the user equipment, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and receive, from the user equipment, a status report relating to the serving cell and the one or more candidate cells.

[0010] In a variant, the lower layer configurations may include one or more of physical (PHY) layer configurations or medium access control (MAC) layer configurations.

[0011] In another variant, the lower layer configurations may include a measurement framework.

[0012] In another variant, the one or more candidate cells of the distributed apparatus may be determined based on an automatic neighbor relation (ANR) list.

[0013] In another variant, the lower layer configurations may be complete configurations.

[0014] In another variant, the lower layer configurations may be partial configurations, including at least one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration, or information relating to the measurement report configuration.

[0015] In another variant, the lower layer configurations indicate a priority for decoding one or more of the lower layer configurations.

[0016] In another variant, the status report may indicate successful reception of the lower layer configurations and a number of lower layer configurations decoded by the user equipment.

[0017] In another variant, the status report may be received periodically per cell change.

[0018] In another variant, the distributed apparatus may further be caused to receive, from the user equipment, a measurement report relating to the serving cell; determine to request at least one additional measurement report based on a set of criteria; transmit, to the user equipment, a measurement report request via a MAC control element (MAC-CE) enabling measurements of the one or more candidate cells by the user equipment; and receive, from the user equipment, a measurement report relating to the serving cell and the one or more candidate cells.

[0019] In another variant, the set of criteria may relate to one or more of positioning information, cell loading status, reference signal receive power, or neighbor cell lists.

[0020] In another variant, the measurement report request may provide one of an updated resource configuration associated with an updated measurement report configuration, an updated resource configuration associated with an existing measurement report configuration, or a pointer to an existing resource configuration associated with the existing measurement report. In another variant, the distributed apparatus may further be caused to select a target cell from the one or more candidate cells based on a measurement report received from the user equipment; activate a transmission configuration indication (TCI) state of the target cell for early downlink synchronization; cause the user equipment to perform an early timing advance for the target cell; transmit, to the user equipment, a cell switch command to perform a cell change to the target cell; receive, from the user equipment, an acknowledgement indicating completion of a cell change to the target cell; and transmit, to the central apparatus, an indication of the cell change.

[0021] In another variant, the lower layer configurations may be encrypted using an encryption algorithm, and the lower layer configurations may be transmitted with at least one additional bit indicating the encryption algorithm for the user equipment to use.

[0022] In another variant, the distributed apparatus may further be caused to select a target cell from the one or more candidate cells based on a measurement report received from the user equipment; and transmit, to the user equipment, a cell switch command to perform a cell change to the target cell, wherein the cell switch command includes one of a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell and previously transmitted to the user equipment, a MAC message providing an updated lower layer configuration associated with the target cell, wherein the updated layer configuration associated with the target cell is updated relative to one of the lower layer configurations previously transmitted to the user equipment, or a MAC message providing a new lower layer configuration associated with the target cell if not already previously transmitted to the user equipment.

[0023] In another variant, the cell switch command may include a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell and previously transmitted to the user equipment.

[0024] In another variant, the cell switch command may include a MAC message providing an updated lower layer configuration associated with the target cell.

[0025] In another variant, the updated layer configuration associated with the target cell may be updated relative to one of the lower layer configurations previously transmitted to the user equipment

[0026] According to a third embodiment, a user equipment is provided. The user equipment may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the user equipment at least to transmit, to a central apparatus of a network node, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus of the network node; receive, from the distributed apparatus, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and transmit, to the distributed apparatus, a status report relating to the serving cell and the one or more candidate cells.

[0027] In a variant, the lower layer configurations may include one or more of physical (PHY) layer configurations or medium access control (MAC) layer configurations.

[0028] In another variant, the lower layer configurations may include a measurement framework.

[0029] In another variant, the lower layer configurations may be complete configurations.

[0030] In another variant, the lower layer configurations may be partial configurations, including at least one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration, or information relating to the measurement report configuration.

[0031] In another variant, the lower layer configurations may indicate a priority for decoding one or more of the lower layer configurations.

[0032] In another variant, the status report may indicate successful reception of the lower layer configurations and a number of lower layer configurations decoded by the user equipment.

[0033] In another variant, the status report may be transmitted periodically per cell change.

[0034] In another variant, the user equipment may further be caused to transmit, to the distributed apparatus, a measurement report relating to the serving cell; receive, from the distributed apparatus, a measurement report request via a MAC control element (MAC-CE) enabling measurements of the one or more candidate cells by the user equipment; and transmit, to the distributed apparatus, a measurement report relating to the serving cell and the one or more candidate cells.

[0035] In another variant, the measurement report request may provide one of an updated resource configuration associated with an updated measurement report configuration, an updated resource configuration associated with an existing measurement report configuration, or a pointer to an existing resource configuration associated with the existing measurement report. In another variant, the user equipment may further be caused to receive, from the distributed apparatus, an activated transmission configuration indication (TCI) state of a target cell for early downlink synchronization; perform an early timing advance for the target cell; receive, from the distributed apparatus, a cell switch command to perform a cell change to the target cell; perform synchronization with the target cell; and transmit, to the distributed apparatus, an acknowledgement indicating completion of a cell change to the target cell.

[0036] In another variant, the cell switch command may include a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell and previously received by the user equipment. In another variant, the cell switch command may include a MAC message providing an updated lower layer configuration associated with the target cell.

[0037] In another variant, the updated layer configuration associated with the target cell may be updated relative to one of the lower layer configurations previously received by the user equipment.

[0038] In another variant, the synchronization with the target cell may be performed without random access according to a validity of the timing advance.

[0039] According to a fourth embodiment, a method performed by a central apparatus is provided. The method may include receiving, from a user equipment, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus; and transmitting, to the distributed apparatus, an indication that the user equipment is connected to the serving cell of the distributed apparatus

[0040] According to a fifth embodiment, a method performed by a distributed apparatus is provided. The method may include receiving, from a central apparatus, an indication that a user equipment is connected to a serving cell of the distributed apparatus; transmitting, to the user equipment, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and receiving, from the user equipment, a status report relating to the serving cell and the one or more candidate cells.

[0041] According to a sixth embodiment, a method performed by a user equipment is provided. The method may include transmitting, to a central apparatus, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus; receiving, from the distributed apparatus, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and transmitting, to the distributed apparatus, a status report relating to the serving cell and the one or more candidate cells.

[0042] According to a seventh embodiment, a central apparatus of a network node is provided. The central apparatus may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the central apparatus at least to transmit, to a distributed apparatus of the network node, a request for lower layer configurations for a serving cell and one or more candidate cells of the distributed apparatus; receive, from the distributed apparatus, a radio resource control (RRC) container including the lower layer configurations for the serving cell and the one or more candidate cells; and transmit, to a user equipment, the RRC container including the lower layer configurations.

[0043] In a variant, the request for the lower layer configurations may be transmitted upon receiving one or more of a RRC message indicating that the user equipment is connected to the serving cell, a capability of the user equipment relating to a number of lower layer configurations the user equipment is capable of decoding, or a higher layer measurement report.

[0044] In another variant, the lower layer configurations may be complete configurations.

[0045] In another variant, the lower layer configurations may be partial configurations, including at least one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration, or information relating to a report configuration.

[0046] In another variant, the RRC container may be transmitted to the user equipment via one of a data radio bearer (DRB) or a signaling radio bearer (SRB).

[0047] In another variant, the central apparatus may further be caused to receive, from the user equipment, a RRC message acknowledging receipt of the lower layer configurations.

[0048] According to an eighth embodiment, a distributed apparatus of a network node is provided. The distributed apparatus may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the distributed apparatus at least to receive, from a central apparatus of the network node, a request for lower layer configurations for a serving cell and one or more candidate cells of the distributed apparatus; and transmit, to the central apparatus, a radio resource control (RRC) container to be forwarded to a user equipment, the RRC container including the lower layer configurations for the serving cell and the one or more candidate cells.

[0049] In a variant, the lower layer configurations may include one or more of physical (PHY) layer configurations or medium access control (MAC) layer configurations.

[0050] In another variant, the lower layer configurations may include a measurement framework.

[0051] In another variant, the one or more candidate cells of the distributed apparatus may be determined based on an automatic neighbor relation (ANR) list.

[0052] In another variant, the lower layer configurations may be complete configurations.

[0053] In another variant, the lower layer configurations may be partial configurations, including at least one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration, or information relating to a measurement report configuration. In another variant, the distributed apparatus may further be caused to receive, from the user equipment, a message acknowledging receipt of the lower layer configurations. In another variant, the distributed apparatus may further be caused to receive, from the user equipment, a measurement report relating to the serving cell; receive, from the user equipment, a request for uplink resources for reporting measurements of the one or more candidate cells; transmit, to the user equipment, information relating to the uplink resources via a MAC control element (MAC-CE); and receive, from the user equipment, a measurement report relating to the serving cell and the one or more candidate cells.

[0054] In another variant, the distributed apparatus may further be caused to select a target cell from the one or more candidate cells based on a measurement report received from the user equipment; activate a transmission configuration indication (TCI) state of the target cell for early downlink synchronization; cause the user equipment to perform an early timing advance for the target cell; transmit, to the user equipment, a cell switch command to perform a cell change to the target cell; receive, from the user equipment, an acknowledgement indicating completion of a cell change to the target cell; and transmit, to the central apparatus, an indication of the cell change.

[0055] In another variant, the cell switch command may include a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell and previously transmitted to the user equipment.

[0056] In another variant, the cell switch command may include a MAC message providing an updated lower layer configuration associated with the target cell.

[0057] In another variant, the updated layer configuration associated with the target cell may be updated relative to one of the lower layer configurations previously transmitted to the user equipment.

[0058] In another variant, the cell switch command may include a MAC message providing a new lower layer configuration associated with the target cell if not already previously transmitted to the user equipment.

[0059] According to a ninth embodiment, a user equipment is provided. The user equipment may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the user equipment at least to receive, from a central apparatus of a network node, a radio resource control (RRC) container including lower layer configurations for a serving cell and one or more candidate cells of a distributed apparatus of the network node; and transmit, to the distributed apparatus, a request for uplink resources for reporting measurements of the one or more candidate cells. In a variant, the user equipment may further be caused to transmit, to the central apparatus, prior to receiving the RRC container, one or more of a RRC message indicating that the user equipment is connected to the serving cell, a capability of the user equipment relating to a number of lower layer configurations the user equipment is capable of decoding, or a higher layer measurement report.

[0060] In another variant, the lower layer configurations may include one or more of physical (PHY) layer configurations or medium access control (MAC) layer configurations.

[0061] In another variant, the lower layer configurations may include a measurement framework.

[0062] In another variant, the lower layer configurations may be complete configurations.

[0063] In another variant, the lower layer configurations may be partial configurations, including at least one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration, or information relating to a measurement report configuration. In another variant, the RRC container may be received via one of a data radio bearer (DRB) or a signaling radio bearer (SRB).

[0064] In another variant, the user equipment may further be caused to transmit, to one or more of the central apparatus or the distributed apparatus, a message acknowledging receipt of the lower layer configurations.

[0065] In another variant, the user equipment may further be caused to, prior to transmitting the request for the uplink resources perform a measurement of a reference signal according to a measurement report configuration associated with the serving cell; transmit, to the distributed apparatus, a measurement report relating to the serving cell; perform one or more additional measurements of one or more additional reference signals according to one or more additional measurement report configurations associated with the one or more candidate cells; and determine whether to perform a cell change based on the one or more measurements.

[0066] In another variant, the user equipment may further be caused to receive, from the distributed apparatus, information relating to the uplink resources via a MAC control element (MAC-CE); and transmit, to the distributed apparatus, a measurement report relating to the serving cell and the one or more candidate cells.

[0067] In another variant, the user equipment may further be caused to receive, from the distributed apparatus, an activated transmission configuration indication (TCI) state of a target cell for early downlink synchronization; perform an early timing advance for the target cell; receive, from the distributed apparatus, a cell switch command to perform a cell change to the target cell; perform synchronization with the target cell; and transmit, to the distributed apparatus, an acknowledgement indicating completion of a cell change to the target cell. In another variant, the cell switch command may include a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell and previously received by the user equipment.

[0068] In another variant, the cell switch command may include a MAC message providing an updated lower layer configuration associated with the target cell.

[0069] In another variant, the updated layer configuration associated with the target cell may be updated relative to one of the lower layer configurations previously received by the user equipment.

[0070] In another variant, the synchronization with the target cell may be performed without random access according to a validity of the timing advance.

[0071] According to a tenth embodiment, a method performed by a central apparatus is provided. The method may include transmitting, to a distributed apparatus, a request for lower layer configurations for a serving cell and one or more candidate cells of the distributed apparatus; receiving, from the distributed apparatus, a radio resource control (RRC) container including the lower layer configurations for the serving cell and the one or more candidate cells; and transmitting, to a user equipment, the RRC container including the lower layer configurations. According to an eleventh embodiment, a method performed by a distributed apparatus is provided. The method may include receiving, from a central apparatus, a request for lower layer configurations for a serving cell and one or more candidate cells of the distributed apparatus; and transmitting, to the central apparatus, a radio resource control (RRC) container to be forwarded to a user equipment, the RRC container including the lower layer configurations for the serving cell and the one or more candidate cells.

[0072] According to a twelfth embodiment, a method performed by a user equipment is provided. The method may include receiving, from a central apparatus, a radio resource control (RRC) container including lower layer configurations for a serving cell and one or more candidate cells of a distributed apparatus; and transmitting, to the distributed apparatus, a request for uplink resources for reporting measurements of the one or more candidate cells.

[0073] BRIEF DESCRIPTION OF THE DRAWINGS:

[0074] For proper understanding of example embodiments, reference should be made to the accompanying drawings, wherein:

[0075] Fig. 1 illustrates a schematic example of a system within a network environment;

[0076] Fig. 2 illustrates a schematic example of a split architecture of a network node;

[0077] Fig. 3 illustrates a diagram of an example lower layer triggered mobility (ETM) procedure; Fig. 4 illustrates a schematic example of a radio resource control (RRC) configuration;

[0078] Fig. 5 illustrates a diagram of an example embodiment of the present disclosure;

[0079] Fig. 6 illustrates a diagram of an example embodiment of the present disclosure;

[0080] Fig. 7 illustrates a diagram of an example method of the present disclosure;

[0081] Fig. 8 illustrates a diagram of an example method of the present disclosure;

[0082] Fig. 9 illustrates a diagram of an example method of the present disclosure;

[0083] Fig. 10 illustrates a diagram of an example method of the present disclosure;

[0084] Fig. 11 illustrates a diagram of an example method of the present disclosure;

[0085] Fig. 12 illustrates a diagram of an example method of the present disclosure;

[0086] Fig. 13 illustrates a schematic block diagram of an example apparatus according to aspects of the present disclosure; and

[0087] Fig. 14 illustrates schematic examples of (tangible and / or non-transitory) computer-readable storage media.

[0088] DETAILED DESCRIPTION:

[0089] It will be readily understood that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of some example embodiments of systems, methods, apparatuses, and computer program products for sensing and localization enhancements is not intended to limit the scope of certain embodiments but is representative of selected example embodiments.

[0090] The features, structures, or characteristics of example embodiments described throughout this specification may be combined in any suitable manner in one or more example embodiments. For example, the usage of the phrases “certain embodiments,” “some embodiments,” or other similar language, throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment. Thus, appearances of the phrases “in certain embodiments,” “in some embodiments,” “in other embodiments,” or other similar language, throughout this specification do not necessarily all refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. In addition, the phrase “set of’ refers to a set that includes one or more of the referenced set members. As such, the phrases “set of,” “one or more of,” and “at least one of,” or equivalent phrases, may be used interchangeably. Further, “or” is intended to mean “and / or,” unless explicitly stated otherwise. Additionally, if desired, the different functions or operations discussed below may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the described functions or operations may be optional or may be combined. As such, the following description should be considered as merely illustrative of the principles and teachings of certain example embodiments, and not in limitation thereof.

[0091] Example embodiments described may be implemented in a radio system. Some examples of a suitable communication networks include a 5G network and / or a 6G network. The 3rd Generation Partnership Project (3GPP) solution to 5G is referred to as New Radio (NR). 6G is envisaged to be a further development of 5G. NR has been envisaged to use multiple-input- multiple-output (MIMO) multi-antenna transmission techniques, more base stations or nodes than the current network deployments of LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller local area access nodes and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates. 5G will likely be comprised of more than one radio access technology / radio access network (RAT / RAN), each optimized for certain use cases and / or spectrum. 5G mobile communications may have a wider range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications, including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6GHz, cmWave and mmWave, and being integrable with existing legacy radio access technologies, such as the LTE.

[0092] The current architecture in LTE networks is distributed in the radio and centralized in the core network. The low latency applications and services in 5G may require bringing the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach may require leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. Edge computing provides a distributed computing environment for application and service hosting. Edge computing also has the ability to store and process content in close proximity to cellular subscribers for faster response time.

[0093] Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications). Edge cloud may be brought into RAN by utilizing network function virtualization (NVF) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. Network slicing allows multiple virtual networks to be created on top of a common shared physical infrastructure. The virtual networks are then customized to meet the specific needs of applications, services, devices, customers, or operators.

[0094] Fig. 1 discloses a schematic of an example system 100 within a network environment illustrating a handover. As shown, the system 100 may generally include a network node 102 and a user equipment (UE) 104. The network node 102 may represent a base station, a TRP, and / or another access point, network entity, and / or the like. The UE 104 may represent a terminal, a user device, a mobile device, a mobile unit, an Internet of Things (loT) device, a smart device, and / or the like. The network node 102 may provide a (current) serving cell 106 and a (candidate) target cell 108 to the UE 104. When the UE 104 moves 110 and transmits measurement reports (e.g. on the serving cell 106 and the target cell 108), the network node 102 may send an indication of a handover configuration for a handover of the UE 104 to the target cell 108. Subsequently, the UE 104 may perform a handover to the target cell 108.

[0095] Although shown with only one network node 102 and only one UE 104, it will be understood that the system 100 may include a plurality of network nodes 102 and / or a plurality of UEs 104. A plurality of network nodes 102 (e.g., gNBs) may be connected to or in communication with each other via an Xn interface over which the network nodes 102 may negotiate. The network nodes 102 may also be connected over next generation (NG) interfaces to a 5G core network (5GC), which may be a 5G equivalent for the core network of LTE. In some applications, the network node 102 (e.g., gNB) may be implemented in a split architecture, each network node 102 having at least one central unit (CU) or central apparatus and one or more distributed units (DUs) or distributed apparatuses.

[0096] Fig. 2 discloses a schematic illustration of a split architecture 200 of a network node 102. As shown, a network node 102 (e.g., a gNB) may be split into a central apparatus 202 (e.g., gNB- CU acting as server or host of the gNB) and a plurality of distributed apparatuses 204 (e.g., gNB -DUs acting as radio heads of the gNB). The central apparatus 202 may at least partly control a plurality of spatially separated distributed apparatuses 204 acting at least as transmit / receive (Tx / Rx) nodes for the network node 102. The central apparatus 202 may further be split into a control plane part 202-1 (e.g., gNB-CU-CP) and a user plane part 202-2 (e.g., gNB-CU-UP). The central apparatus 202 may communicate with the distributed apparatuses 204 via an Fl interface (e.g., Fl-C for control plane exchanges and Fl-U for user plane exchanges). The control plane part 202-1 of the central apparatus 202 may further communicate with the user plane part 202-2 of the central apparatus 202 via an El interface. Network node operations may be carried out at least partly in the central apparatus 202 or distributed among a plurality of central apparatuses 202. The distribution of work between core network operations and base station operations may vary depending on implementation. The central apparatus 202 may comprise or host higher or upper protocol layers, such as a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and an internet protocol (IP) layer. The distributed apparatus 204 may comprise or host lower protocol layers, such as a radio link control (RLC) layer, a medium access control (MAC) layer, and a physical (PHY) layer. Such 5G CU-DU split architecture may be implemented using cloud / server so that the central apparatus 202 handling upper layers is disposed in a cloud and the distributed apparatuses 204 handling lower layers are closer to or comprise actual radio and antenna units. Further, a single distributed apparatus 204 may be configured to host a plurality of cells. Such split architectures can be particularly beneficial in dense networks.

[0097] Referring back to Fig. 1, a handover from a serving cell to a candidate or target cell can be performed in a number of different ways. Until recently (e.g., until Release 17 3GPP standards), all types of handovers were triggered by layer 3 (L3) measurements and executed via RRC signaling (e.g., reconfiguration and synchronization). Such handovers involved reconfiguration of higher or upper layers (e.g., RRC or PDCP) and / or resetting of lower layers (e.g., MAC and / or PHY) which led to longer latency, larger overhead, and longer interruption times than beam level mobility. More recent developments (e.g., Release 18 3GPP standards) have introduced layer 1 (Ll) / layer 2 (L2) based mobility also known as lower layer triggered mobility (LTM) to enable a serving cell change via L1 / L2 signaling. More particularly, with LTM, it is possible for a distributed apparatus 204 (e.g., the lower layers thereof) to trigger a cell switch using layer 2 MAC commands based on layer 1 measurements (e.g., reference signal received power (RSRP) of beams (e.g., synchronization signal block (SSBs)) from candidate cells. By maintaining the configurations of the upper layers and / or reducing reconfigurations of the lower layers, LTM aids in reducing latency, overhead, and / or interruption time associated with handovers.

[0098] Fig. 3 discloses a diagram of an example LTM procedure 300. As shown, the LTM procedure 300 is generally comprised of four phases including a preparation phase 302, an early synchronization phase 304, an execution phase 306, and a completion phase 308. During the preparation phase 302, a central apparatus 202 of a serving cell (e.g., serving CU) identifies candidate target cells based on L3 measurement reports, prepares the target cells, and shares the target cell configurations with the UE 104. During the early synchronization phase 304, the distributed apparatus 204 of the serving cell (e.g., serving DU) asks (considering LI measurements) the UE 104 to perform timing advance (TA) acquisition for a specific target cell. During the execution phase 306, the distributed apparatus 204-1 of the serving cell (e.g., serving DU) decides (considering LI measurements) on the target cell and asks the UE 104 to switch to the target cell, and the UE 104 switches to the target cell. During the completion phase 308, UE context may be released from the other unselected cells. In some cases, the UE context may be maintained by the other unselected cells for a period of time as determined by the central apparatus 202. In cases where the UE 104 maintains the configurations of the target cell, the UE 104 may perform multiple / subsequent LTM operations (e.g., subsequent LTM). Fig. 4 discloses a schematic example of a RRC configuration (or reconfiguration) process 400 in a CU-DU split architecture. The RRC configuration process 400 may be needed for configuring a UE 104 for a L3 handover, for configuring a UE 104 for a LTM procedure 300, or for configuring a UE 104 for new measurement reports, etc. As shown in Fig. 4 and with further reference to Fig. 3, the distributed apparatus 204 may be responsible for configuring the lower layer parameters for the UE 104. If the central apparatus 202 decides to configure LTM (e.g., Step 3 of Fig. 3), the central apparatus 202 may request the lower layer parameters from the distributed apparatus 204 (e.g., Steps 4-7 of Fig. 3). In turn, the central apparatus 202 may pack the lower layer parameters provided by the distributed apparatus 204 together with upper layer parameters or configurations in a RRC reconfiguration message (e.g., Step 8 of Fig. 3) to be transmitted in downlink (DL) to the UE 104 via the distributed apparatus 204 (e.g., Steps 9-10 of Fig. 3).

[0099] Conventional LTM (e.g., the LTM procedure 300 shown in Fig. 3 and as specified in Release 18) may offer some overall benefits, but there is still room for improvement. Using LTM, a base station or gNB (e.g., network node 102) may prepare and configure up to eight candidate cells in one RRC configuration (or reconfiguration). Also under conventional LTM, an association between a resource configuration and a measurement report configuration is provided by the central unit (e.g., central apparatus 202) of the gNB and fixed when a RRC configuration is sent to a user equipment (e.g., UE 104). However, if an update to any of the eight candidate cells (e.g., an update to such associations between resource configurations and measurement report configuration) need to be provided to the user equipment, the central unit must trigger another RRC configuration process for each additional update. While the RRC configuration process can take a relatively long time to complete, repeating the RRC configuration process for each potential update may further compound delays in dense networks or high-speed mobility scenarios (e.g., train lines, etc.).

[0100] In 6G, dense networks may be highly likely or common. In a dense network, each central unit (e.g., central apparatus 202) may manage several distributed units (e.g., distributed apparatuses 204), and each distributed unit may host several cells. Given such a dense network, the number of possible handovers needed could be quite significant, for instance, between cells of a single distributed unit, between cells across different distributed units, and / or between cells across different distributed units managed by different central units. Since a central unit needs to receive lower layer parameters from the distributed unit and compile RRC configurations for each handover, a central unit in a dense network may be subject to extra processing loads and extra traffic therethrough. Also since configuration elements created at the distributed unit need to travel through the central unit for each handover, this can cause extra delays for user equipment awaiting to receive the necessary lower layer configurations. As networks continue to grow and as such dense networks or high-speed mobility scenarios become more commonplace, there is a need to explore further ways to enable faster switching in support of environments prone to frequent handovers.

[0101] Accordingly, there is a need for a solution that can sufficiently support dense networks while reducing unnecessary burdens on the network and / or user equipment. The present disclosure presents such solutions. In particular, the present disclosure provides solutions which enable lower layer configurations to be sent from or updated by a distributed unit to a user equipment in a manner that minimizes involvement from a central unit. For example, the distributed unit may send lower layer configurations to the user equipment directly (e.g., as a payload or in a new MAC message format) or indirectly via the central unit (e.g., using a RRC container). Furthermore, associations between resource configuration and measurement report configurations, which are normally handled by the central unit, may be managed or updated by the distributed unit for even more flexibility. By providing the distributed unit with more direct control over lower layer configurations, it is possible to perform lower layer cell switching with minimal recurring RRC configurations (or reconfigurations), which can be significant in dense networks or high-speed mobility scenarios. In this way, the present disclosure can reduce unnecessary signaling, processing loads, reduce traffic, as well as delays to the user equipment or network. Fig. 5 discloses a diagram of one example embodiment 500 of lower layer cell switching according to the present disclosure. As shown, the embodiment 500 may involve a UE 104, a central apparatus 202 of a serving cell (e.g., Serving CU), and a distributed apparatus 204 (e.g., Serving DU1 / MM, DUECelll, DUl:Cell2, DUl:Cell3) that may be associated with the serving cell and one or more other candidate cells. Although Fig. 5 depicts a single central apparatus 202 that is managing a single distributed apparatus 204 associated with three cells, solutions of the present disclosure may similarly be extended to different numbers or arrangements of central apparatuses 202, distributed apparatuses 204, and / or cells. In some examples, certain operations shown in Fig. 5 as being performed by the distributed apparatus 204 may be performed by a mobility manager (MM). The MM may be another entity, a subentity, or an entity otherwise associated with a lower layer (e.g., MAC layer) of the distributed apparatus 204 and tasked with managing configurations for lower layer cell switching or mobility. The MM may be comprised in or comprised of the distributed apparatus 204.

[0102] At 500-0 of Fig. 5, initial access may be performed, during which the UE 104 may acquire a full RRC configuration (e.g., PDCP, REC, MAC, and PHY layer parameters) of a given serving cell from the network via the serving central apparatus 202 and / or the serving distributed apparatus 204. At 500-1, the UE 104 may be connected to the serving cell and have a RRC connection with the central apparatus 202. For instance, the UE 104 may transmit, and the central apparatus 202 may receive, a RRC message indicating that the UE 104 is connected to the serving cell of the distributed apparatus 204. In some examples, the central apparatus 202 may receive a capability report, an L3 measurement report, and / or the like. In response to the information received from the UE 104, and while the UE 104 is in a RRC_Connected state, the central apparatus 202 at 500-2 may transmit, and the distributed apparatus 204 may receive, an indication that the UE 104 is connected to the serving cell of the distributed apparatus 204 and to prepare for or initiate lower layer cell switching or mobility.

[0103] At 500-3 of Fig. 5, the distributed apparatus 204 may transmit, and the UE 104 may receive, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus 204. For instance, the distributed apparatus 204 (e.g., the MAC layer thereof) may transmit the lower layer configurations (e.g., PHY and MAC layer configurations) to the UE 104 directly via a payload or in a new or modified MAC message format. In one example, the modified MAC message format may be relayed to the UE 104 via encapsulation in an additional protocol layer (e.g., in an RLC Acknowledgement Mode (AM) layer). Use of such an additional protocol layer may provide segmentation and re-transmission and also reduce burdens to the distributed apparatus 204 as the additional protocol layer is already disposed at the distributed apparatus 204. Although this is but one possible means by which to relay the lower layer configurations, it will be understood that other means could also be used to produce similar effects.

[0104] The lower layer configurations provided by the distributed apparatus 204 at 500-3 of Fig. 5 may include configurations for all available candidate cells, a set of candidate cells, or a subset of candidate cells that are associated with the distributed apparatus 204. In some examples, a set or a subset of candidate cells may be at least partially determined based on or with reference to an automatic neighbor relation (ANR) list. In some examples, the lower layer configurations may indicate to the UE 104 a priority value or some other indication associated with one or more of the serving or candidate cells. For example, the priority indication may be a specific indication to prioritize the decoding of the lower layer configurations associated with a certain set or subset of candidate cells over those of other candidate cells. In some examples, the priority indication may be a general indication to prioritize the decoding of lower layer parameters over upper layer parameters irrespective of the candidate cells.

[0105] Furthermore, the lower layer configurations may provide a resource configuration associated with a measurement report configuration. The lower layer configurations may include one or more PHY layer configurations, MAC layer configurations, measurement frameworks, and / or the like. In some examples, the lower layer configurations may be complete configurations, e.g., including all PHY and MAC layer parameters. In other examples, the lower layer configurations may be partial configurations including the minimal information needed for completing a handover. For example, a partial lower layer configuration may include at least one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration (e.g., which may be referenced by a resource configuration using an index, a pointer, etc.), information relating to a measurement report configuration (e.g., type, content, periodicity, uplink resources, pointers to resource configurations, or other parameters), and / or the like

[0106] At 500-4 of Fig. 5, the UE 104 may transmit, and the distributed apparatus 204 may receive, a status report relating to the serving cell and the one or more candidate cells. The status report may indicate successful reception of the lower layer configurations. In some examples, the status report may indicate a number of lower layer configurations that have been decoded by the UE 104 and are ready for measurements. The status report may be transmitted or updated periodically, aperiodically, or after every cell change. In some examples, the status report may be appended to an existing UE channel resource via which the UE 104 may be able to transmit the status report to the distributed apparatus 204. At 500-5 of Fig. 5, the UE 104 may transmit, and the distributed apparatus 204 may receive, a measurement report relating to the serving cell. For example, the measurement report may include a LI report that could be used for beam management purposes, mobility purposes, and / or the like. Once the serving cell has been measured, in some examples, the UE 104 may begin performing measurements of other candidate cells using the lower layer configurations obtained from the distributed apparatus 204 at 500-3.

[0107] At 500-6 of Fig. 5, the distributed apparatus 204 may determine to request at least one additional measurement report based on a set of criteria. For example, the set of criteria may relate to one or more of positioning information, cell loading status, RSRP, neighbor cell lists, and / or the like. At 500-7 of Fig. 5, the distributed apparatus 204 may transmit, and the UE 104 may receive, a measurement report request for measurements of one or more of the candidate cells. The measurement report request may be transmitted via a MAC control element (MAC- CE) which enables the UE 104 to measure the one or more candidate cells. The measurement report request may also provide and / or indicate appropriate resource configurations and measurement report configurations, or appropriate associations between resource configurations and measurement report configurations, for the UE 104 to use for the additional measurements. For example, the measurement report request may refer to an existing resource configuration or an existing measurement report configuration (e.g., provided at 500-3), a new or updated resource configuration or a new or updated measurement report configuration (e.g., provided at 500-7), or a combination thereof.

[0108] In a first example, the measurement report request at 500-7 may provide an updated association, including an updated resource configuration that is associated with an updated measurement report configuration. In a second example, the measurement report request may provide an updated resource configuration that is associated with an existing measurement report configuration (e.g., provided at 500-3). In a third example, the measurement report request may provide a pointer, an index, and / or another reference to an existing resource configuration (e.g., provided at 500-3) that is associated with an existing measurement report (e.g., provided at 500-3). In some alternative examples, the UE 104 may be configured or preconfigured with LI triggered reporting of candidate cell measurements. In such examples, the distributed apparatus 204 may not need to request additional measurement reports from the UE 104, in which case the measurement report request at 500-7 may be omitted.

[0109] At 500-8 of Fig. 5, the UE 104 may transmit, and the distributed apparatus 204 may receive, a measurement report as requested by the distributed apparatus 204 at 500-7. The measurement report may be transmitted using an association between a resource configuration and a measurement report configuration as indicated by the distributed apparatus 204 at 500-3 and / or 500-7. Additionally, the measurement report may include measurements relating to the one or more candidate cells. In some examples, the measurement report may further include an updated measurement relating to the serving cell. In some alternative examples, the UE 104 may be configured with LI triggered reporting of candidate cell measurements. In such examples, the UE 104 may be able to perform and transmit the measurement report of candidate cells at 500-8 without first receiving the measurement report request from the distributed apparatus at 500-7.

[0110] At 500-9 of Fig. 5, the distributed apparatus 204 may begin identifying or selecting one or more of the candidate cells to use as potential target cells. For instance, the distributed apparatus 204 may select one or more potential target cells based on measurements provided via the measurement report from the UE 104 at 500-8. Moreover, at 500-9, the distributed apparatus 204 may activate one or more transmission configuration indication (TCI) states associated with the potential target cells for early downlink synchronization, and at 500-10, the distributed apparatus 204 may trigger or cause the UE 104 to perform early TA with the potential target cells. At 500-11 of Fig. 5, the distributed apparatus 204 may decide to initiate a cell switch (e.g., to change the serving cell to one of the target cells). At 500-12 of Fig. 5, the distributed apparatus 204 may transmit, and the UE 104 may receive, a cell switch command to perform the cell change to the target cell. As shown, the cell switch command may be transmitted by the MAC layer of the distributed apparatus 204 and as a MAC-CE, as a MAC message including the MAC-CE, and / or the like.

[0111] In some examples, the cell switch command may simply comprise of a MAC-CE which includes a pointer, an index, or another form of reference to one of the existing lower layer configurations already provided to the UE 104 at 500-3 or 500-7. The pointer may enable the UE 104 to identify the lower layer configuration associated with the target cell that can be used for performing the cell switch. In other examples, the cell switch command may comprise of a MAC message which provides an updated set of parameters or updated lower layer configurations associated with the target cell that the UE 104 can use for performing the cell switch. In some instances, the updated lower layer configurations may be updated associations in relation to existing lower layer configuration already provided to the UE 104 at 500-3 or 500-7. In some other instances, the new or updated lower layer configurations may be new associations and / or configurations not previously provided to the UE 104.

[0112] At 500-13 of Fig. 5, the UE 104 may perform synchronization with the target cell based on the cell switch command provided by the distributed apparatus at 500-12 (e.g., based on a pointer provided as a MAC-CE, based on an updated lower layer configuration provided as a MAC message, etc.). Moreover, depending on the validity of the TA, the UE 104 may perform the synchronization with the target cell at 500-13 with or without random access. At 500-14 of Fig. 5, the UE 104 may transmit, and the distributed apparatus 204 may receive, an acknowledgement indicating completion of the cell change. Moreover, due to the lower layer mobility enabled by the present disclosure, the UE 104 does not need to send a RRC message (e.g., RRCReconfigComplete) to the central apparatus 202, but rather simply send the acknowledgement to the distributed apparatus 204 to indicate a successful handover. Accordingly, the MAC-CE acknowledgement at 500-14 may be a compulsory acknowledgement, as opposed to a conventional MAC-CE acknowledgement that may be optional.

[0113] At 500-15 of Fig. 5, the UE 104 may then connect to the target cell (e.g., cell 2). At 500-16 of Fig. 5, the distributed apparatus 204 may transmit, and the central apparatus 202 may receive, an indication of the cell change. For instance, the indication may include an updated cell identifier and / or an updated cell radio network temporary identifier (C-RNTI). More particularly, a C-RNTI may be assigned to the UE 104 by the distributed apparatus 204 and used to uniquely identify the UE 104. Conventionally, the C-RNTI may be communicated during a random access channel (RACH) procedure between the central apparatus 202 and the UE 104. However, the present disclosure enables the distributed apparatus 204 to directly inform the central apparatus 202 of the identity of the UE 104 (e.g., using the C-RNTI) after a successful cell change. Furthermore, conventionally, a central apparatus 202 may assign a new C-RNTI per cell change of a UE 104. However, in some examples, such as in intra-DU or intra-gNB handover scenarios described here, the C-RNTI may remain unchanged. Thus, while the C-RNTI provided at 500-16 may remain the same, the indication may nonetheless inform the central apparatus 202 that the UE 104 has moved to a different cell e.g., as identified by a physical cell identity (PCI).

[0114] Furthermore, once the UE 104 is connected to the target cell, any one or more of the procedures indicated above may be repeated as needed. For instance, at 500-17 of Fig. 5, similar to the procedure at 500-4, the UE 104 may transmit, and the distributed apparatus 204 may receive, a subsequent status report relating to the target cell (e.g., now new serving cell) and one or more candidate cells. The subsequent status report may be based on one or more of the lower layer configurations already provided by the distributed apparatus 204 at 500-3, 500-7, and / or 500-12. It may be up to the UE 104 to determine when to begin decoding cells based on the lower layer configurations, but once decoded, the UE 104 may indicate to the distributed apparatus 204 via the subsequent status report the availability of the cells, the number of lower layer configurations that have been decoded, and / or the number of cells that are ready for measurements.

[0115] The procedures illustrated at 500-18 through 500-26 of Fig. 5 similarly follow the procedures at 500-6 through 500-16 discussed above and are shown to illustrate how the example embodiment 500 may be extended to additional cell changes or handovers. In some examples, MAC messages initiated by the network node 102 (e.g., the distributed apparatus 202) may be secured, protected, encrypted, etc. at different security levels and aligned to corresponding MAC responses from the UE 104. For example, a MAC message transmitted by the distributed apparatus 204 (e.g., at one or more of 500-3, 500-7, 500-12, 500-19, and / or 500-22 of Fig. 5) may be encrypted using an encryption algorithm. The MAC message may include one or more additional bits indicating the encryption algorithm for the UE 104 to use e.g., to decrypt the MAC message, to use for encrypting a response to the MAC message, etc. Aside from an encryption algorithm, in some cases the MAC message and / or the one or more additional bits may refer to a security algorithm, a security key generation algorithm, an encryption key generation algorithm, and / or some other such mechanism that is aligned with a security level of the expected MAC response from the UE 104. Such a security mechanism can be used to thwart potential security breaches and ensure that the MAC message received at the UE 104 and / or the MAC response received at the distributed apparatus 204 is authentic.

[0116] Fig. 6 discloses a diagram of another example embodiment 600 of lower layer cell switching according to the present disclosure. As in the previous embodiment 500 of Fig. 5, the embodiment 600 may involve a UE 104, a central apparatus 202 of a serving cell (e.g., Serving CU), and a distributed apparatus 204 (e.g., Serving DU1 / MM, DUl:Celll, DUl:Cell2, DUl:Cell3) that may be associated with the serving cell and one or more other candidate cells. Although Fig. 6 depicts a single central apparatus 202 that is managing a single distributed apparatus 204 associated with three cells, solutions of the present disclosure may similarly be extended to different numbers or arrangements of central apparatuses 202, distributed apparatuses 204, and / or cells. In some examples, certain operations shown in Fig. 6 as being performed by the distributed apparatus 204 may be performed by a MM. As previously discussed, the MM may be another entity, a sub-entity, or an entity otherwise associated with a lower layer (e.g., MAC layer) of the distributed apparatus 204 and tasked with managing configurations for lower layer cell switching or mobility. The MM may be comprised in or comprised of the distributed apparatus 204. At 600-0 of Fig. 6, initial access may be performed, during which the UE 104 may acquire a full RRC configuration (e.g., PDCP, RLC, MAC, and PHY layer parameters) of a given serving cell from the network via the serving central apparatus 202 and / or the serving distributed apparatus 204. At 600-1, the UE 104 may be connected to the serving cell and have a RRC connection with the central apparatus 202. For instance, the UE 104 may transmit, and the central apparatus 202 may receive, a RRC message indicating that the UE 104 is connected to the serving cell of the distributed apparatus 204. In some examples, the central apparatus 202 may receive a capability report, an L3 measurement report, and / or the like. In response to the information received from the UE 104, and while the UE 104 is in a RRC_Connected state, the central apparatus 202 at 600-2 may transmit, and the distributed apparatus 204 may receive, a request for lower layer configurations (e.g., PHY and MAC layer parameters) for the serving cell and one or more candidate cells of the distributed apparatus 204.

[0117] At 600-3 of Fig. 6, the distributed apparatus 204 may transmit, and the central apparatus 202 may receive, lower layer configurations via a container. The container may be a RRC container, e.g., a container that can be routed from the central apparatus 202 to the UE 104 via a data radio bearer (DRB) or a signaling radio bearer (SRB) in a RRC message and capable of containing or encapsulating the lower layer configurations provided by the distributed apparatus 204. In some examples, the container may be defined or specified by a RRC information element (IE). The lower layer configurations may be associated with the serving cell and one or more candidate cells, and may include one or more PHY layer configurations, MAC layer configurations, measurement frameworks, and / or the like. As previously discussed, the lower layer configurations may be complete configurations, e.g., including all PHY and MAC layer parameters, or partial configurations including the minimal information needed for completing a handover, e.g., including one or more of a random access configuration, a timing advance acquisition configuration, a reference signal configuration, information relating to a measurement report configuration, and / or the like.

[0118] At 600-4 of Fig. 6, the central apparatus 202 may transmit, and the UE 104 may receive, the container including the lower layer configurations. The container may be sent to the UE 104 via DRB or SRB in a RRC message and include at least the lower layer configurations that have been configured for the UE 104 by the distributed apparatus 204. In some examples, the container and / or the RRC message may include upper layer parameters configured for the UE 104 by the central apparatus 202. At 600-5 of Fig. 6, the UE 104 may transmit an indication or message acknowledging receipt of the lower layer configurations. In one example, the UE 104 may transmit, and the distributed apparatus 204 may receive, an acknowledgement message (e.g., via a MAC message) confirming receipt of the lower layer configurations. In another example, the UE 104 may transmit, and the central apparatus 202 may receive, an acknowledgement message (e.g., via RRCReconfigComplete or another type of RRC message) confirming receipt of the lower layer configurations.

[0119] At 600-6 of Fig. 6, the UE 104 may perform one or more measurements of one or more reference signals associated with the serving cell. For instance, the UE 104 may perform the measurements in accordance with a measurement report configuration provided via the container. At 600-7 of Fig. 6, the UE 104 may transmit, and the distributed apparatus 204 may receive, a measurement report of the serving cell which can be used for beam management purposes, mobility purposes, and / or the like. For example, the measurement report may include LI measurements of reference signals from the serving cell. In other examples, the measurement report may further include LI measurements of reference signals from other cells (e.g., candidate cells). At 600-8 of Fig. 6, the UE 104 may perform one or more additional measurements of one or more additional reference signals associated with one or more of the candidate cells. The additional measurements may be performed in accordance with corresponding measurement report configurations as previously provided via the container at 600-4 of Fig. 6. At 600-9 of Fig. 6, the UE 104 may determine whether to perform a cell change based on the one or more measurements performed, e.g., at 600-6 or 600-8.

[0120] At 600-10 of Fig. 6, the UE 104 may transmit, and the distributed apparatus 204 may receive, a request for uplink resources for reporting measurements of the one or more candidate cells or an indication that measurements of the candidate cells are ready or available. At 600-11 of Fig. 6, the distributed apparatus 204 may transmit, and the UE 104 may receive information relating to the uplink resources via a MAC-CE. For example, the MAC-CE may indicate resource configurations that the UE 104 can use to transmit the measurement report associated with the candidate cells. At 600-12 of Fig. 6, the UE 104 may transmit, and the distributed apparatus 204 may receive, a measurement report relating to the candidate cells. For instance, the measurement report may include LI measurements of reference signals from the candidate cells that are transmitted via the uplink resources provided by the distributed apparatus 204 at 600-11. In some examples, the measurement report may further include updated measurements associated with the serving cell. In some examples, the measurement report may be an aperiodic report that can be used for triggering a cell switch.

[0121] At 600-13 of Fig. 6, the distributed apparatus 204 may begin identifying or selecting one or more of the candidate cells to use as potential target cells. For instance, the distributed apparatus 204 may select one or more potential target cells based on measurements provided via the measurement report from the UE 104 at 600-7 or 600-12. Moreover, at 600-13, the distributed apparatus 204 may activate one or more TCI states associated with the potential target cells for early downlink synchronization, and at 600-14, the distributed apparatus 204 may trigger or cause the UE 104 to perform early TA with the potential target cells. At 600- 15 of Fig. 6, the distributed apparatus 204 may decide to initiate a cell switch (e.g., to change the serving cell to one of the target cells). At 600-16 of Fig. 6, the distributed apparatus 204 may transmit, and the UE 104 may receive, a cell switch command to perform the cell change to the target cell. As shown, the cell switch command may be transmitted by the MAC layer of the distributed apparatus 204 and as a MAC-CE, as a MAC message including the MAC- CE, and / or the like.

[0122] As in the examples of embodiment 500 of Fig. 5, the cell switch command of embodiment 600 of Fig. 6 may simply comprise of a MAC-CE which includes a pointer, an index, or another form of reference to one of the existing lower layer configurations already provided to the UE 104 at 600-4. The pointer may enable the UE 104 to identify the lower layer configuration associated with the target cell that can be used for performing the cell switch. In other examples, the cell switch command may comprise of a MAC message which provides an updated set of parameters or updated lower layer configurations associated with the target cell that the UE 104 can use for performing the cell switch. In some instances, the updated lower layer configurations may be updated associations in relation to existing lower layer configuration already provided to the UE 104 at 600-4. In some other instances, the new or updated lower layer configurations may be new associations and / or configurations not previously provided to the UE 104 that the UE 104 can use to perform the cell switch to the target cell.

[0123] At 600-17 of Fig. 6, the UE 104 may perform synchronization with the target cell based on the cell switch command provided by the distributed apparatus at 600-16 (e.g., based on a pointer provided as a MAC-CE, based on an updated lower layer configuration provided as a MAC message, etc.). Moreover, depending on the validity of the TA, the UE 104 may perform the synchronization with the target cell at 600-17 with or without random access. At 600-18 of Fig. 6, the UE 104 may transmit, and the distributed apparatus 204 may receive, an acknowledgement indicating completion of the cell change. Moreover, due to the lower layer mobility enabled by the present disclosure, the UE 104 does not need to send a RRC message (e.g., RRCReconfigComplete) to the central apparatus 202, but rather simply send the acknowledgement to the distributed apparatus 204 to indicate a successful handover. Accordingly, the MAC-CE acknowledgement at 500-14 may be a compulsory acknowledgement, as opposed to a conventional MAC-CE acknowledgement that may be optional.

[0124] At 600-19 of Fig. 6, the UE 104 may then connect to the target cell (e.g., cell 2). At 600-20 of Fig. 6, the distributed apparatus 204 may transmit, and the central apparatus 202 may receive, an indication of the cell change. For instance, the indication may include an updated cell identifier and / or an updated cell radio network temporary identifier (C-RNTI). More particularly, as discussed above, a C-RNTI may be assigned to the UE 104 by the distributed apparatus 204 and used to uniquely identify the UE 104. Conventionally, the C-RNTI may be communicated during a RACH procedure between the central apparatus 202 and the UE 104. However, using the lower layer mobility enabled by the present disclosure, the distributed apparatus 204 may be able to directly inform the central apparatus 202 of the identity of the UE 104 (e.g., using the C-RNTI) after a successful cell change or handover. Furthermore, conventionally, a central apparatus 202 may assign a new C-RNTI per cell change of a UE 104. However, in some examples, such as in intra-DU or intra-gNB handover scenarios described here, the C-RNTI may remain unchanged. Thus, although the C-RNTI provided at 600-20 may remain the same, the indication may nonetheless be used to inform the central apparatus 202 that the UE 104 has moved to a different cell e.g., as identified by a PCI.

[0125] Furthermore, once the UE 104 is connected to the target cell, any one or more of the procedures indicated above may be repeated as needed. For instance, at 600-21 of Fig. 6, similar to the procedure at 600-10, the UE 104 may transmit, and the distributed apparatus 204 may receive, a subsequent request for uplink resources for reporting additional measurements of the one or more candidate cells or an indication that additional measurements of the candidate cells are ready or available. At 600-22 of Fig. 6, the distributed apparatus 204 may transmit, and the UE 104 may receive uplink resources via a MAC-CE that the UE 104 can use for the reporting the measurements as previously discussed.

[0126] The procedures illustrated at 600-23 through 600-29 of Fig. 6 similarly follow the procedures previously discussed at 600-12 through 600-20 discussed above and are shown to illustrate how the example embodiment 600 may be extended to additional cell changes or handovers. In some examples, MAC messages initiated by the network node 102 (e.g., the distributed apparatus 202) may be secured, protected, encrypted, etc. at different security levels and aligned to corresponding MAC responses from the UE 104. For example, a MAC message transmitted by the distributed apparatus 204 (e.g., at one or more of 500-3, 500-7, 500-12, SOO- 19, and / or 500-22 of Fig. 5) may be encrypted using an encryption algorithm. The MAC message may include one or more additional bits indicating the encryption algorithm for the UE 104 to use e.g., to decrypt the MAC message, to user for encrypting a response to the MAC message, etc. Aside from an encryption algorithm, in some cases the MAC message and / or the one or more additional bits may refer to a security algorithm, a security key generation algorithm, an encryption key generation algorithm, and / or some other such mechanism that is aligned with a security level of the expected MAC response from the UE 104. Such a security mechanism can be used to thwart potential security breaches and ensure that the MAC message received at the UE 104 and / or the MAC response received at the distributed apparatus 204 is authentic.

[0127] Fig. 7 discloses a diagram of one example method 700 according to some aspects of the present disclosure. The method 700 may illustrate example operations of a central unit (e.g., a central apparatus 202). Some of the operations illustrated in Fig. 7 may be similar to some operations shown in and described with respect to Fig. 5.

[0128] In an embodiment, the method 700 may include, at 702, receiving, from a user equipment, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus; and at 704, transmitting, to the distributed apparatus, an indication that the user equipment is connected to the serving cell of the distributed apparatus. Fig. 8 discloses a diagram of another example method 800 according to some aspects of the present disclosure. The method 800 may illustrate example operations of a distributed unit (e.g., a distributed apparatus 204). Some of the operations illustrated in Fig. 8may be similar to some operations shown in and described with respect to Fig. 5.

[0129] In an embodiment, the method 800 may include, at 802, receiving, from a central apparatus, an indication that a user equipment is connected to a serving cell of the distributed apparatus; at 804, transmitting, to the user equipment, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and at 806, receiving, from the user equipment, a status report relating to the serving cell and the one or more candidate cells.

[0130] Fig. 9 discloses a diagram of another example method 900 according to some aspects of the present disclosure. The method 900 may illustrate example operations of a user equipment (e.g., a UE 104). Some of the operations illustrated in Fig. 9 may be similar to some operations shown in and described with respect to Fig. 5.

[0131] In an embodiment, the method 900 may include, at 902, transmitting, to a central apparatus, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus; at 904, receiving, from the distributed apparatus, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and at 906, transmitting, to the distributed apparatus, a status report relating to the serving cell and the one or more candidate cells.

[0132] Fig. 10 discloses a diagram of another example method 1000 according to some aspects of the present disclosure. The method 1000 may illustrate example operations of a central unit (e.g., a central apparatus 202). Some of the operations illustrated in Fig. 10 may be similar to some operations shown in and described with respect to Fig. 6.

[0133] In an embodiment, the method 1000 may include, at 1002, transmitting, to a distributed apparatus, a request for lower layer configurations for a serving cell and one or more candidate cells of the distributed apparatus; at 1004, receiving, from the distributed apparatus, a radio resource control (RRC) container including the lower layer configurations for the serving cell and the one or more candidate cells; and at 1006, transmitting, to a user equipment, the RRC container including the lower layer configurations.

[0134] Fig. 11 discloses a diagram of another example method 1100 according to some aspects of the present disclosure. The method 1100 may illustrate example operations of a distributed unit (e.g., a distributed apparatus 204). Some of the operations illustrated in Fig. 11 may be similar to some operations shown in and described with respect to Fig. 6.

[0135] In an embodiment, the method 1100 may include, at 1102, receiving, from a central apparatus, a request for lower layer configurations for a serving cell and one or more candidate cells of the distributed apparatus; and at 1104, transmitting, to the central apparatus, a radio resource control (RRC) container to be forwarded to a user equipment, the RRC container including the lower layer configurations for the serving cell and the one or more candidate cells.

[0136] Fig. 12 discloses a diagram of another example method 1200 according to some aspects of the present disclosure. The method 1200 may illustrate example operations of a user equipment (e.g., a UE 104). Some of the operations illustrated in Fig. 12 may be similar to some operations shown in and described with respect to Fig. 6.

[0137] In an embodiment, the method 1200 may include, at 1202, receiving, from a central apparatus, a radio resource control (RRC) container including lower layer configurations for a serving cell and one or more candidate cells of a distributed apparatus; and at 1204, transmitting, to the distributed apparatus, a request for uplink resources for reporting measurements of the one or more candidate cells.

[0138] Fig. 13 is a schematic block diagram of an example embodiment of an apparatus 1300 according to aspects of the present disclosure. The apparatus 1300 may be comprised in or comprised of, for instance, a network node (e.g., network node 102), a user equipment (e.g., UE 104), a central unit (e.g., central apparatus 202), a distributed unit (e.g., distributed apparatus 204), and / or another network entity. As shown, the apparatus 1300 may include at least one or more of a processor 1302, a program memory 1304, a working or main memory 1306, a communication interface 1308, and an optional user interface 1310. Some or all of the components of the apparatus 1300 may for instance be connected via a bus. Some or all of the components of the apparatus 1300 may for instance be combined into one or more modules.

[0139] In some embodiments, the apparatus 1300 (e.g., a network node, a user equipment, a central unit, a distributed unit, or another network entity) may comprise at least one processor 1302, and at least one memory 1304 storing instructions that, when executed by the at least one processor 1302, cause the apparatus 1300 to at least perform and / or control any one of the methods 700, 800, 900, 1000, 1100, 1200 discussed above. The processor 1302 may for instance further control the memories 1304, 1306, the communication interface 1308, and / or the optional user interface 1310. The processor 1302 may execute program code stored in the program memory 1304, which may for instance represent a readable storage medium comprising program code that, when executed by the processor 1302, causes the processor 1302 to perform any one of the methods 700, 800, 900, 1000, 1100, 1200 discussed above.

[0140] In some embodiments, the apparatus 1300 (e.g., a network node, a user equipment, a central unit, a distributed unit, or another network entity) may be configured to perform and / or control or comprise respective means (e.g., one or more of the processor 1302, the program memory 1304, the working or main memory 1306, the communication interface 1308, and the optional user interface 1310) for performing and / or controlling any one of the methods 700, 800, 900, 1000, 1100, 1200 discussed above.

[0141] The processor 1302 may be a processor of any suitable type. The processor 1302 may comprise, but is not limited to, one or more microprocessors, one or more processors with accompanying one or more digital signal processors, one or more processors without accompanying digital signal processors, one or more special-purpose computer chips, one or more field-programmable gate arrays (FPGAs), one or more controllers, one or more application-specific integrated circuits (ASICs), one or more computers / servers, or other types of relevant structure / hardware that may be programmed in such a way to perform any one of the methods 700, 800, 900, 1000, 1100, 1200 discussed above. In some examples, the processor 1302 may be or include an application processor that runs an operating system.

[0142] The program memory 1304 may also be included in the processor 1302. The program memory 1304 may for instance be fixedly connected to the processor 1302, or be at least partially removable from the processor 1302, for instance in the form of a memory card or stick. The program memory 1304 may for instance be non-volatile memory. The program memory 1304 may for instance be or at least partially include a flash memory, a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a hard disc, and / or the like. The program memory 1304 may also comprise an operating system for the processor 1302. The program memory 1304 may also comprise a firmware for the apparatus 1300.

[0143] The communication interface 1308 may enable the apparatus 1300 to communicate with other apparatuses 1300 (e.g., another network node, another user equipment, another central unit, another distributed unit, and / or another network entity). The communication interface 1308 may for instance comprise a wireless interface, e.g. a cellular radio communication interface and / or a WLAN interface) and / or wire-bound interface, e.g. an Internet Protocol (IP)-based interface, for instance, to communicate with entities via the Internet. The communication interface 1308 may enable the apparatus 1300 to communicate with other network entities, for instance, one or more network entities as comprised in a mobile communication network. The user interface 1310 is optional and may comprise a display for displaying information to a user and / or an input device (e.g., a keyboard, a keypad, a touchpad, a mouse, etc.) for receiving information from a user.

[0144] Fig. 14 is a schematic illustration of examples of (tangible and / or non-transitory) computer- readable storage media according to the present disclosure that may for instance be used to implement the program memory 1304 and / or the main memory 1306 of Fig. 13. As shown, the program memory 1304 and / or the main memory 1306 may be implemented using a flash memory 1402, which may for instance be soldered or bonded to a printed circuit board, a solid- state drive 1404 comprising a plurality of memory chips (e.g., flash memory chips), a magnetic hard drive 1406, a Secure Digital (SD) card 1408, a Universal Serial Bus (USB) memory stick 1410, an optical storage medium 1412 (such as for instance a CD-ROM or DVD), a magnetic storage medium 1414, and / or the like.

[0145] In the present disclosure, any presented connection in the described embodiments is to be understood in a way that the involved components are operationally coupled. Thus, the connections can be direct or indirect with any number or combination of intervening elements, and there may be merely a functional relationship between the components.

[0146] Moreover, any of the methods, processes, or actions described or illustrated herein may be implemented using executable instructions in a general-purpose or special-purpose processor and stored on a computer-readable storage medium (e.g., disk, memory, and / or the like) to be executed by such a processor. References to a “computer-readable storage medium” should be understood to encompass specialized circuits such as FPGAs, ASICs, signal processing devices, and other devices.

[0147] The expression “A and / or B” is considered to comprise any one of the following three scenarios: (i) A, (ii) B, (iii) A and B. Furthermore, the article “a” is not to be understood as “one,” i.e., use of the expression “an element” does not preclude that also further elements are present. The term “comprising” is to be understood in an open sense, i.e., in a way that an object that “comprises an element A” may also comprise further elements in addition to element A. Further, the term “comprising” may be limited to “consisting of,” i.e., consisting of only the specified elements.

[0148] The expression “at least one of the following: (a list of two or more elements)” and “at least one of (a list of two or more elements)” and similar wording, where the list of two or more elements are joined by “and” or “or,” mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0149] It will be understood that all presented embodiments are only examples, and that any feature presented for a particular example embodiment may be used with any aspect on its own or in combination with any feature presented for the same or another particular example embodiment and / or in combination with any other feature not mentioned. In particular, the example embodiments presented in this disclosure shall also be understood to be disclosed in all possible combinations with each other, as far as it is technically reasonable and the example embodiments are not necessarily alternatives with respect to each other. It will further be understood that any feature presented for an example embodiment in a particular category (method / apparatus / computer program / system) may also be used in a corresponding manner in an example embodiment of any other category. It should also be understood that presence of a feature in the presented example embodiments shall not necessarily mean that this feature forms an essential feature and cannot be omitted or substituted.

[0150] The statement of a feature comprises at least one of the subsequently enumerated features is not mandatory in the way that the feature comprises all subsequently enumerated features, or at least one feature of the plurality of the subsequently enumerated features. Also, a selection of the enumerated features in any combination or a selection of only one of the enumerated features is possible. The specific combination of all subsequently enumerated features may as well be considered. Also, a plurality of only one of the enumerated features may be possible. The sequence of all method steps presented above is not mandatory, also alternative sequences may be possible. Nevertheless, the specific sequence of method steps exemplarily shown in the drawings shall be considered as one possible sequence of method steps for the respective embodiment described by the respective drawing.

[0151] The subject-matter has been described above by means of examples. It should be noted that there are alternative ways and variations which are obvious to a skilled person in the art and can be implemented without deviating from the scope of the appended claims.

[0152] PARTIAL GLOSSARY

[0153] ANR Automatic Neighbor Relation

[0154] C-RNTI Cell Radio Network Temporary Identifier

[0155] CU Central Unit

[0156] DL Downlink

[0157] DRB Data Radio Bearer

[0158] DU Distributed Unit gNB 5G Base Station

[0159] IE Information Element

[0160] HO Handover

[0161] LTM L1 / L2 Triggered Mobility

[0162] MAC Medium Access Control

[0163] MAC-CE Medium Access Control-Control Element

[0164] MIB Master Information Block

[0165] NR New Radio (5G)

[0166] NW Network

[0167] PCI Physical Cell Identity

[0168] PDCCH Physical Downlink Control Channel

[0169] PDCP Packet Data Convergence Protocol

[0170] PHY Physical Layer

[0171] PRS Positioning Reference Signal

[0172] RACH Random Access Channel

[0173] RLC Radio Link Control

[0174] RRC Radio Resource Control

[0175] RS Reference Signal

[0176] RSRP Reference Signal Received Power SDAP Service Data Application Protocol

[0177] SCS Subcarrier Spacing

[0178] SRB Signaling Radio Bearer

[0179] SRS Sounding Reference Signal TA Timing Advance

[0180] TCI Transmission Configuration Indication

[0181] TMSI Temporary Mobile Subscriber Identity

[0182] UE User Equipment

[0183] UL Uplink

Claims

CLAIMS:

1. A distributed apparatus of a network node, comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the distributed apparatus at least to: receive, from a central apparatus of the network node, an indication that a user equipment is connected to a serving cell of the distributed apparatus; transmit, to the user equipment, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and receive, from the user equipment, a status report relating to the serving cell and the one or more candidate cells.

2. The distributed apparatus of claim 1, wherein the lower layer configurations are partial configurations, including at least one or more of: a random access configuration, a timing advance acquisition configuration, a reference signal configuration, or information relating to the measurement report configuration.

3. The distributed apparatus of any of claims 1-2, wherein the status report indicates one or more of a successful reception of the lower layer configurations or a number of lower layer configurations decoded by the user equipment.

4. The distributed apparatus of any of claims 1-3, further caused to: receive, from the user equipment, a measurement report relating to the serving cell; determine to request at least one additional measurement report based on a set of criteria; transmit, to the user equipment, a measurement report request via a MAC control element (MAC-CE) enabling measurements of the one or more candidate cells by the user equipment; and receive, from the user equipment, a measurement report relating to the serving cell andthe one or more candidate cells.

5. The distributed apparatus of claim 4, wherein the measurement report request provides one of: an updated resource configuration associated with an updated measurement report configuration, an updated resource configuration associated with an existing measurement report configuration, or a pointer to an existing resource configuration associated with the existing measurement report.

6. The distributed apparatus of any of claims 1-5, wherein the lower layer configurations are encrypted using an encryption algorithm, and wherein the lower layer configurations are transmitted with at least one additional bit indicating the encryption algorithm for the user equipment to use.

7. The distributed apparatus of any of claims 1-6, further caused to: select a target cell from the one or more candidate cells based on a measurement report received from the user equipment; and transmit, to the user equipment, a cell switch command to perform a cell change to the target cell, wherein the cell switch command includes one of: a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell previously transmitted to the user equipment, a MAC message providing an updated lower layer configuration associated with the target cell, wherein the updated layer configuration associated with the target cell is updated relative to one of the lower layer configurations previously transmitted to the user equipment, or a MAC message providing a new lower layer configuration associated with the target cell if not already previously transmitted to the user equipment.

8. A user equipment, comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the userequipment at least to: transmit, to a central apparatus of a network node, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus of the network node; receive, from the distributed apparatus, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and transmit, to the distributed apparatus, a status report relating to the serving cell and the one or more candidate cells.

9. The user equipment of claim 8, wherein the status report indicates one or more of a successful reception of the lower layer configurations or a number of lower layer configurations decoded by the user equipment.

10. The user equipment of any of claims 8-9, further caused to: transmit, to the distributed apparatus, a measurement report relating to the serving cell; receive, from the distributed apparatus, a measurement report request via a MAC control element (MAC-CE) enabling measurements of the one or more candidate cells by the user equipment; and transmit, to the distributed apparatus, a measurement report relating to the serving cell and the one or more candidate cells.

11. The user equipment of claim 10, wherein the measurement report request provides one of: an updated resource configuration associated with an updated measurement report configuration, an updated resource configuration associated with an existing measurement report configuration, or a pointer to an existing resource configuration associated with the existing measurement report.

12. The user equipment of any of claims 8-11, further caused to: receive, from the distributed apparatus, an activated transmission configuration indication (TCI) state of a target cell for early downlink synchronization;perform an early timing advance for the target cell; receive, from the distributed apparatus, a cell switch command to perform a cell change to the target cell; perform synchronization with the target cell; and transmit, to the distributed apparatus, an acknowledgement indicating completion of a cell change to the target cell.

13. The user equipment of claim 12, wherein the cell switch command includes one of a MAC-CE providing a pointer to one of the lower layer configurations associated with the target cell and previously received by the user equipment, or a MAC message providing an updated lower layer configuration associated with the target cell, and wherein the updated layer configuration associated with the target cell is updated relative to one of the lower layer configurations previously received by the user equipment.

14. A method performed by a distributed apparatus, comprising: receiving, from a central apparatus, an indication that a user equipment is connected to a serving cell of the distributed apparatus; transmitting, to the user equipment, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and receiving, from the user equipment, a status report relating to the serving cell and the one or more candidate cells.

15. A method performed by a user equipment, comprising: transmitting, to a central apparatus, a radio resource control (RRC) message indicating that the user equipment is connected to a serving cell of a distributed apparatus; receiving, from the distributed apparatus, lower layer configurations for the serving cell and one or more candidate cells of the distributed apparatus, the lower layer configurations providing a resource configuration associated with a measurement report configuration; and transmitting, to the distributed apparatus, a status report relating to the serving cell and the one or more candidate cells.

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