Base station system, and radio unit and method thereof.

Abstract

It provides a functional split for base stations suitable for beamforming. [Solution] At least one of a wireless unit (RU), a distributed unit (DU), and a controller that performs near real-time control of wireless access network elements and resources including at least a DU is configured to perform both channel estimation and channel prediction.

Description

Technical Field

[0001] This disclosure relates to functional splitting of base stations in a wireless communication network.

Background Art

[0002] The Open Radio Access Network (O-RAN) Alliance is a community of mobile network operators, vendors, and research and academic institutions with the mission of restructuring radio access networks (RANs) to be more intelligent, open, virtualized, and fully interoperable. The O-RAN Alliance provides O-RAN technical specifications that define a standardized Open RAN architecture and interfaces. The standardization of interfaces by the O-RAN Alliance is built on the foundation established by the 3rd Generation Partnership Project (3GPP (registered trademark)).

[0003] The open interfaces defined by the O-RAN technical specifications include the open fronthaul interface between an O-RAN radio unit (O-RU) and an O-RAN distributed unit (O-DU) (see Non-Patent Document 1). The open fronthaul interface between the O-RU and the O-DU is a logical interface and is also known as lower layer split (LLS).

[0004] The current O-RAN technical specification supports split option 7-2x among the different LLS options and specifies two variations, Category A and Category B (see, for example, Section 4.2 of Non-Patent Document 1). Split option 7-2x is one option belonging to option 7, which is an intra-physical (PHY) layer split, where the low PHY layer functions are located on the O-RU and the high PHY layer functions, Radio Link Control (RLC) functions, and Medium Access Control (MAC) functions are located on the O-DU. Category A and Category B differ in the placement of downlink precoding. In Category A, the precoding functions are located above the open fronthaul interface, i.e., on the O-DU, while in Category B, the precoding functions are located below the open fronthaul interface, i.e., on the O-RU.

[0005] According to the intra-PHY layer function split in split option 7-2x for 5th Generation (5G) New Radio (NR) downlink, particularly for Physical Downlink Shared Channel (PDSCH), scrambling, modulation, layer mapping, and resource element (RE) mapping are located in the O-DU. On the other hand, digital beamforming, inverse fast Fourier Transform (IFFT), and cyclic prefix (CP) addition are located in the O-RU. Furthermore, in the case of Category A O-RU, precoding is performed in the O-DU, and beamforming in the O-RU excludes the calculation of precoding. In contrast, in the case of Category B O-RU, precoding is performed in the O-RU. In this case, precoding may be included in the digital beamforming processing block within the O-RU.

[0006] For 5G NR uplinks, particularly for Physical Uplink Shared Channels (PUSCH), the intra-PHY layer function split in split option 7-2x places FFT and CP removal on the O-RU. Meanwhile, RE demapping, equalization, (PUSCH Demodulation Reference Signal (DMRS) based) channel estimation, demodulation, and descrambling are placed on the O-DU. In addition, for uplink Sounding Reference Signals (SRS), FFT and CP removal are placed on the O-RU, and RE demapping and (SRS based) channel estimation are placed on the O-DU. The results of SRS-based channel estimation can be used for one or both of the precoding and beamforming for downlink transmissions, such as PDSCH transmissions using a reciprocity-based beamforming approach. The results of SRS-based channel estimation can also be used for uplink beamforming, such as in PUSCH.

[0007] The O-RAN Alliance agreed in June 2023 to two new open fronthaul interfaces optimized for uplinks in massive multiple-input multiple-output (mMIMO) configurations. These new interfaces are called Next-Generation LLS (NG-LLS) or Uplink Performance Improvement (ULPI) interfaces. The new interfaces are intended to improve mMIMO uplink performance in current Category B O-RU or Category B split configurations. One of the two new interfaces is called NG-LLS Class A, Category B ULPI-A, or 7.2x ULPI with DMRS-EQ. The other of the two new interfaces is called NG-LLS Class B, Category B ULPI-B, or 7.2x ULPI with DMRS-NEQ.

[0008] NG-LLS Class A and NG-LLS Class B share the common feature of placing uplink DMRS channel estimation and uplink beamforming weight calculation in the O-RU. However, the main difference between NG-LLS Class A and NG-LLS Class B is that the NG-LLS Class A specification places the equalizer function in the O-RU, while the NG-LLS Class B specification places it in the O-DU. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] O-RAN ALLIANCE Working Group 4, "Control, User and Synchronization Plane Specification 14.0", O-RAN.WG4.CUS.0-R003-v14.00, February 2024 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The functional splitting of base stations has been found to present various technical challenges and room for improvement. Base stations may also be referred to by other terms such as RAN nodes, radio stations, or access points. One of these challenges concerns functional splitting suitable for SRS-based beamforming to improve mMIMO downlink performance. In particular, it is unclear which logical unit within the O-RAN, specifically the O-RU, O-DU, O-CU, or Near Real-Time (RT) RAN Intelligent Controller (RIC), is appropriate to encompass the channel prediction function. Because the fronthaul interface between the O-DU and O-RU has stringent latency requirements, determining the appropriate architecture can impact control plane (C-plane) traffic. Furthermore, such an architecture can also affect throughput performance.

[0011] In 5G NR, the SRS is an uplink reference signal that is set specifically for the User Equipment (UE). The SRS is used by the base station (e.g., gNB, O-DU) for UL channel sounding, i.e., uplink channel estimation between the UE and the base station (e.g., O-RU, gNB). In the uplink, the results of SRS-based uplink channel estimation may be used for purposes including, but are not limited to, calculating uplink beamforming weights (e.g., at least one of codebook-type or non-codebook-type beamforming), link adaptation, rank adaptation, channel-dependent scheduling, timing control, and beam management. Furthermore, in downlinks (e.g., downlinks in time-division duplex (TDD) systems), SRS-based uplink channel estimation can be used for purposes including, but are not limited to, calculating reciprocity-based downlink precoding weights (or beamforming weights) (e.g., at least one of codebook-type or non-codebook-type beamforming), link adaptation, rank adaptation, and channel-dependent scheduling. Additionally, SRS-based uplink channel estimation may have other uses and applications that are not listed here but can be understood to improve system performance.

[0012] When SRS-based uplink channel estimation is used in at least one of the uplink beamforming weight calculations and the downlink beamforming weight calculations (leveraging TDD channel interoperability), the channel prediction function can improve beamforming performance. Channel prediction operation can enable the base station to obtain a predicted channel estimate during time slots when the most recent channel estimate is unavailable.

[0013] For example, consider an uplink scenario. A base station can calculate an uplink beamforming matrix in the time slot when an SRS is received. The base station may then continue to use this same uplink beamforming matrix in all subsequent PUSCH slots until the next SRS is received. This use of an older uplink beamforming matrix can degrade uplink throughput. Similarly, consider the case of downlink beamforming based on reciprocity with SRS. A base station can calculate a downlink beamforming matrix in the time slot when an SRS is received. The base station may then continue to use this same downlink beamforming matrix in all PDSCH slots until the next SRS is received. This use of an older downlink beamforming matrix can degrade downlink throughput.

[0014] Uplink channel estimates can be updated by frequently transmitting SRS on the uplink, but this can incur pilot overhead, resulting in fewer opportunities to transmit data (PUSCH) signals and reduced uplink throughput. In contrast, channel prediction operations use historical values ​​of channel estimates (calculated from received uplink SRS) and can use these historical values ​​to predict or extrapolate channel estimates in time slots where SRS transmissions are not scheduled (e.g., PUSCH or PDSCH transmission slots). SRS-based channel prediction includes temporal predictions using the results of SRS-based channel estimations. SRS-based channel prediction may also include predictions of future channel characteristics using the results of past SRS-based channel estimations.

[0015] The placement of channel prediction functionality has not yet been addressed in the O-RAN Alliance's discussions on NG-LLS. Therefore, determining the appropriate placement of channel prediction functionality in the O-RAN NG-LLS architecture to support efficient beamforming operation in at least one of the uplink and downlink is a critical technical challenge.

[0016] Other challenges concern the placement of the functionality for dynamically allocating SRS resources to the UE. In particular, it is unclear which logical units within the O-RAN, specifically O-RU, O-DU, O-CU, or Near-RT RIC, are appropriate to have dynamic SRS resource allocation functionality. Furthermore, it is unclear what signaling exchanges are necessary between logical units with dynamic SRS resource allocation functionality and other logical units.

[0017] One of the objectives that the embodiments disclosed herein seek to achieve is to provide an apparatus, method, and / or program that contributes to solving at least one of several problems relating to the functional splitting of a base station, including the problems described above. It should be noted that this objective is only one of several objectives that the embodiments disclosed herein seek to achieve. Other objectives or problems and novel features will be revealed by the description herein or by the accompanying drawings. [Means for solving the problem]

[0018] In a first embodiment, the base station system includes a RU configured to perform lower physical layer signal processing, a DU configured to perform upper physical layer signal processing, and a controller configured to perform near real-time control of RAN elements and resources, including at least the DU. Furthermore, one of the RU, the DU, and the controller is configured to perform both channel estimation and channel prediction.

[0019] In a second embodiment, the RU is configured to communicate via a fronthaul interface with a DU configured to (a) perform lower physical layer signal processing and (b) perform higher physical layer signal processing. Furthermore, the RU is configured to perform channel estimation and channel prediction.

[0020] In a third aspect, the method performed by the RU includes (a) performing lower physical layer signal processing, (b) communicating via a fronthaul interface with a DU configured to perform higher physical layer signal processing, and (c) performing channel estimation and channel prediction.

[0021] In a fourth embodiment, the method includes manufacturing one of the RU, DU, and controller to perform both channel estimation and channel prediction.

[0022] In a fifth aspect, the DU is configured to (a) communicate with an RU configured to perform lower physical layer signaling via a fronthaul interface, (b) perform higher physical layer signaling, and (c) perform at least one of uplink scheduling and downlink scheduling. In addition, the DU is configured to receive information from the RU or CU configured to perform dynamic uplink SRS resource allocation, indicating the dynamically determined uplink SRS resource allocation to the UE.

[0023] In the sixth aspect, the method performed by the DU includes (a) communicating with a RU configured to perform lower physical layer signaling via a fronthaul interface; (b) performing higher physical layer signaling; (c) performing at least one of uplink scheduling and downlink scheduling; and (d) receiving information from the RU or CU configured to perform dynamic uplink SRS resource allocation indicating a dynamically determined uplink SRS resource allocation to the UE.

[0024] In a seventh aspect, the RU is configured to communicate with a DU configured to perform (a) lower physical layer signal processing and (b) upper physical layer signal processing via a fronthaul interface. In addition, the RU is configured to dynamically allocate uplink SRS resources to a UE. The RU is further configured to send information indicating the uplink SRS resource allocation to the UE to the DU configured to perform at least one of uplink scheduling and downlink scheduling.

[0025] In an eighth aspect, the method performed by the RU includes: (a) performing lower physical layer signal processing; (b) communicating with a DU configured to perform upper physical layer signal processing via a fronthaul interface; (c) dynamically allocating uplink SRS resources to a UE; and (d) sending information indicating the uplink SRS resource allocation to the UE to the DU configured to perform at least one of uplink scheduling and downlink scheduling.

[0026] In a ninth aspect, the DU is configured to communicate with a RU configured to perform lower physical layer signal processing via a fronthaul interface, perform (b) upper physical layer signal processing, and (c) perform at least one of uplink scheduling and downlink scheduling. In addition, the DU is configured to send information indicating at least one of uplink resource allocation and downlink resource allocation to the UE to the RU or CU configured to perform dynamic uplink SRS resource allocation to the UE.

[0027] In the tenth aspect, the method performed by the DU includes: (a) communicating with an RU configured to perform lower physical layer signal processing via a fronthaul interface; (b) performing upper physical layer signal processing; (c) performing at least one of uplink scheduling and downlink scheduling; and (d) sending information indicating at least one of uplink resource allocation and downlink resource allocation to the UE to the RU or CU configured to perform dynamic uplink SRS resource allocation to the UE.

[0028] In the eleventh aspect, the RU is configured to: (a) perform lower physical layer signal processing and (b) communicate with a DU configured to perform upper physical layer signal processing via a fronthaul interface. In addition, the RU is configured to dynamically allocate uplink SRS resources to the UE. The RU is further configured to receive information indicating at least one of uplink resource allocation and downlink resource allocation to the UE from the DU.

[0029] In the twelfth aspect, the method performed by the RU includes: (a) performing lower physical layer signal processing; (b) communicating with a DU configured to perform upper physical layer signal processing via a fronthaul interface; (c) dynamically allocating uplink SRS resources to the UE; and (d) receiving information indicating at least one of uplink resource allocation and downlink resource allocation to the UE from the DU.

[0030] In the thirteenth aspect, the program includes a set of instructions (or software code) for causing a computer to perform the method according to any of the above aspects (e.g., the sixth or tenth aspect) when loaded into the computer.

Advantages of the Invention

[0031] According to the above-described embodiment, it is possible to provide an apparatus, method, and / or program that contributes to solving at least one of several problems related to the functional split of a base station, including the problems described above. [Brief explanation of the drawing]

[0032] [Figure 1] This figure shows an O-RAN logic architecture relating to one or more embodiments. [Figure 2] This figure shows example configurations of O-DU, O-CU Control Plane (CP), O-CU User Plane (UP), and Near-RT RIC related to one or more embodiments. [Figure 3] This figure shows an example of the configuration of an O-RU related to one or more embodiments. [Figure 4A] This figure shows the operation of uplink transmission from a UE to a base station in a wireless communication system to which embodiments of the present disclosure apply. [Figure 4B] This figure shows the operation of downlink transmission from a base station to a UE in a wireless communication system to which embodiments of the present disclosure apply. [Figure 4C] This figure shows an example of the problem of calculating downlink beamforming weights that cause channel changes over time in a wireless communication system to which embodiments of the present disclosure apply. [Figure 4D] This figure shows an example of channel prediction for mitigating channel changes over time in a wireless communication system to which embodiments of the present disclosure apply. [Figure 4E] This figure shows an example of a problem in channel prediction in a wireless communication system to which embodiments of this disclosure apply. [Figure 4F] This figure shows an example of eigenvector prediction for mitigating channel time-dependent changes in a wireless communication system to which embodiments of the present disclosure apply. [Figure 4G] This figure shows the functional configuration of a base station equipped with a channel predictor to which embodiments of the present disclosure are applied. [Figure 4H]This figure shows the functional configuration of a base station equipped with an eigenvector predictor to which embodiments of the present disclosure are applied. [Figure 5A] This figure shows an example of a base station function split relating to one or more embodiments. [Figure 5B] This figure shows an example of a base station function split relating to one or more embodiments. [Figure 5C] This figure shows an example of a base station function split relating to one or more embodiments. [Figure 5D] This figure shows an example of a base station function split relating to one or more embodiments. [Figure 5E] This figure shows an example of a base station function split relating to one or more embodiments. [Figure 5F] This figure shows an example of a base station function split relating to one or more embodiments. [Figure 6A] This figure shows an example of base station function splitting and signaling relating to one or more embodiments. [Figure 6B] This figure shows an example of base station function splitting and signaling relating to one or more embodiments. [Figure 7A] This figure shows an example of a message for communication between functional splits in one embodiment of the present disclosure. [Figure 7B] This figure shows an example of a message for communication between functional splits in one embodiment of the present disclosure. [Figure 7C] This figure shows an example of a message for communication between functional splits in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0033] The following describes specific embodiments in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary for clarity.

[0034] The multiple embodiments described below can be implemented individually or in combination as needed. These embodiments have novel features that differ from each other. Therefore, these multiple embodiments may contribute to achieving different objectives or solving different problems and may contribute to producing different effects.

[0035] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps shown in any of the drawings may be changed as appropriate.

[0036] The following embodiments are primarily described for wireless communication systems conforming to the 3GPP 5G NR technical specifications and the O-RAN technical specifications. However, these embodiments may also be applied to other wireless communication systems supporting similar technologies. In particular, these embodiments may be applied to future Beyond 5G or 6G systems and wireless communication systems conforming to future extended O-RAN technical specifications.

[0037] As used herein, depending on the context, “(if)” may be interpreted as meaning “when,” “at or around the time,” “after,” “upon,” “in response to determining,” “in accordance with a determination,” or “in response to detecting.” These expressions may be interpreted as having the same meaning depending on the context.

[0038] First, the configuration and operation of several network elements common to multiple embodiments will be described. Figure 1 shows an example configuration of a wireless communication system including one or more base stations relating to multiple embodiments. As mentioned above, base stations may also be referred to by other terms such as RAN nodes, radio stations, or access points. In particular, if a base station includes multiple logical or physical elements with functional splitting, it may be called a base station system, RAN node system, radio station system, or access point system. For example, a base station may be a gNB in ​​a 5G system, but is not limited to these. In the example of Figure 1, the wireless communication system follows an O-RAN logical architecture. In the example of Figure 1, the system includes a Service Management and Orchestration (SMO) framework 1, Non-RT RIC 2, Near-RT RIC 3, O-CU Control Plane (CP) 4, O-CU User Plane (UP) 5, O-DU 6, O-RU 7, and O-Cloud 8. Each element (network function) shown in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a running software instance on dedicated hardware, or as an instantiated virtualization function on an application platform.

[0039] SMO Framework 1 may also be simply called SMO. SMO Framework 1 provides various logical functions that are not anchored within Non-RT RIC 2. These logical functions include, but are not limited to, O1 termination, O2 termination, open fronthaul (OFH) Management plane (M-plane) termination, and external terminations. O1 termination enables SMO Framework 1 to exchange messages over the O1 interface with Near-RT RIC 3, as well as with E2 nodes such as O-CU-CP 4, O-CU-UP 5, and O-DU 6. O2 termination enables SMO Framework 1 to exchange messages over the O2 interface with O-Cloud 8. O-Cloud 8 is a cloud computing platform consisting of a collection of physical infrastructure nodes that meet O-RAN requirements, hosting relevant O-RAN functions, supporting software components, and appropriate management and orchestration capabilities. Related O-RAN functions include, for example, Near-RT RIC 3 and E2 nodes. OFH M-plane termination enables SMO Framework 1 to communicate with O-RU 7 for non-real-time management operations related to open fronthaul. External termination enables SMO Framework 1 or Non-RT RIC 2 to exchange messages with external entities via an interface outside the O-RAN range.

[0040] Non-RT RIC 2 is a logical function within the SMO framework 1. Non-RT RIC 2 consists of a Non-RT RIC framework and Non-RT RIC applications (rApps). The Non-RT RIC framework includes the functionality to logically terminate the A1 interface and expose a set of R1 services to rApps. The A1 termination allows the Non-RT RIC framework and Near-RT RIC 3 to exchange messages over the A1 interface. The set of R1 services includes A1-related services and O1-related services, along with other services. Typical execution times for use cases involving non-real-time control loops (loops) between Non-RT RIC 2 and Near-RT RIC 3, E2 nodes, and O-RU 7 are 1 second or longer.

[0041] A1-related services, along with other services, include creating, updating, querying, and deleting A1 policies, querying the enforcement status of A1 policies, and subscribing to event notifications related to A1 policies, including notifications of changes in the enforcement status of A1 policies.

[0042] O1-related services are provided by the SMO Framework 1 and the Non-RT RIC Framework. These O1-related services enable rApps to retrieve information about alarms, network-related performance information, the current network configuration, provision changes to the network configuration, and retrieve additional network-related information.

[0043] Near-RT RIC 3 is a logical function that enables near real-time control and optimization of RAN elements and resources through granular (e.g., UE basis, cell basis) data acquisition and action on the E2 interface. Typical execution times for use cases involving near real-time control loops (loops) by or between Near-RT RIC 3 and E2 nodes are on the order of 10 milliseconds to 1 second.

[0044] Near-RT RIC 3 hosts a set of applications called xApps and provides a set of platform functions commonly used to support specific functionalities hosted by xApps. This set of platform functions includes databases and a shared data layer (SDL), xApp subscription management, conflict mitigation, messaging infrastructure, interface termination, and application programming interface (API) enablement. Interface termination includes E2 termination, A1 termination, and O1 termination, which provide termination for the E2, A1, and O1 interfaces, respectively.

[0045] The E2 interface connects the Near-RT RIC 3 to one or more E2 nodes. An E2 node is a logical node that terminates the E2 interface. An E2 node is a RAN node and exposes one or more RAN functions to the Near-RT RIC 3 and hosted xApps. For NR access, as shown in Figure 1, the E2 node includes O-CU-CP 4, O-CU-UP 5, and O-DU 6. Control loops within the E2 node, such as O-CU-CP 4, O-CU-UP 5, or O-DU 6, can typically operate in less than 10 milliseconds (e.g., radio scheduling within O-DU 6).

[0046] O-CU-CP 4 is a logical node that hosts the control plane functions of the gNB-CU as defined in the 3GPP technical specifications, specifically the control plane portions of Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP). O-CU-CP 4 supports E1 Application Protocol (E1AP) signaling on the E1 interface between the gNB-CU-CP and gNB-CU-UP as defined in the 3GPP technical specifications, for communication with O-CU-UP 5. O-CU-CP 4 supports F1AP signaling on the F1-C interface between the gNB-CU-CP and gNB-DU as defined in the 3GPP technical specifications, for communication with O-DU 6. O-CU-CP 4 provides an E2 interface termination for communication with Near-RT RIC 3. In addition, O-CU-CP 4 provides an O1 interface termination for communication with SMO Framework 1.

[0047] O-CU-UP 5 is a logical node that hosts the user plane functions of the gNB-CU as defined in the 3GPP technical specifications, specifically the user plane portion of PDCP and the Service Data Adaptation Protocol (SDAP). O-CU-UP 5 supports E1AP signaling as defined in the 3GPP technical specifications for communication with O-CU-CP 4. O-CU-UP 5 supports the F1-U interface as defined in the 3GPP technical specifications for communication with O-DU 6. The F1-U interface uses the General Packet Radio Service Tunnelling Protocol User Plane (GTP-U) protocol. The GTP-U protocol uses GTP-U tunnels to carry encapsulated user data packets and signaling messages. O-CU-UP 5 provides an E2 interface termination for communication with Near-RT RIC 3. In addition, O-CU-UP 5 provides an O1 interface termination for communication with SMO Framework 1.

[0048] O-DU 6 is a logical node that hosts the RLC and MAC layers of the gNB as defined in the 3GPP technical specifications, and also hosts a portion of the gNB's PHY layer, i.e., the high PHY layer. High PHY layer signal processing for 5G NR downlink, particularly for PDSCH, includes, for example, scrambling, modulation, layer mapping, and RE mapping. Precoding for downlink transmission may be performed on O-DU 6 (i.e., Category A O-RU) or on O-RU 7 (i.e., Category B O-RU).

[0049] O-DU 6 supports the F1-C and F1-U interfaces specified in the 3GPP technical specifications for communication with O-CU-CP 4 and O-CU-UP 5. O-DU 6 provides an E2 interface termination for communication with Near-RT RIC 3. O-DU 6 provides an O1 interface termination for communication with SMO Framework 1. In addition, O-DU 6 provides an OFH interface termination for communication with O-RU 7. The OFH interface includes the OFH M-plane and the Control User Synchronization (CUS) plane.

[0050] O-RU 7 is a logical node that hosts the remaining PHY layer signal processing of the gNB, i.e., the low PHY layer. Low PHY layer signal processing for 5G NR downlink, particularly for PDSCH, includes, for example, digital beamforming, IFFT, and cyclic prefix (CP) addition. As mentioned above, precoding for downlink transmission may be performed in O-DU 6 (i.e., Category A O-RU) or in O-RU 7 (i.e., Category B O-RU). In the case of Category B O-RU, precoding may be included in the digital beamforming processing block within O-RU 7.

[0051] O-RU 7 provides an OFH interface termination for communication with O-DU 6, which includes an OFH M-plane and a CUS plane. In addition, O-RU 7 provides an OFH M-plane termination for communication with SMO framework 1.

[0052] The O-RU 7 further includes a digital front end (DFE) and a radio frequency (RF) front end (FE). Signal processing in the DFE includes, for example, digital pre-distortion (DPD), crest factor reduction (CFR), digital up-conversion (DUC), and digital down-conversion (DDC). The RF FE includes, for example, power amplifiers (PAs), low-noise amplifiers (LNAs), bandpass filters, digital-to-analog converters (DACs), and analog-to-digital converters (ADCs).

[0053] Some or all of Near-RT RIC 3, O-CU-CP 4, O-CU-UP 5, and O-DU 6 can operate on commercially available (COTS) or purpose-built hardware. Some or all of the RAN networking functions provided by Near-RT RIC 3, O-CU-CP 4, O-CU-UP 5, and O-DU 6 may be implemented on a virtualization or cloud platform such as O-Cloud 8.

[0054] A virtualization or cloud platform such as O-Cloud 8 is a collection of hardware and software components that provide computing power to run virtualized RAN network functions. The hardware of the virtualization or cloud platform includes computing, networking, and storage components. The hardware of the virtualization or cloud platform is augmented with hardware accelerators as needed. The software of the virtualization or cloud platform provides application programming interfaces (APIs) for managing the lifecycle of virtualized RAN network functions. The virtualization or cloud platform may use virtual machines (VMs) orchestrated and managed with OpenStack®, or containers orchestrated and managed with Kubernetes®, or both, to implement virtualized (or containerized or cloud-based) RAN network functions.

[0055] Figure 2 shows an example configuration of Near-RT RIC 3, O-CU-CP 4, O-CU-UP 5, and O-DU 6. In the example in Figure 2, Near-RT RIC 3, O-CU-CP 4, O-CU-UP 5, and O-DU 6 are implemented using a general-purpose computer system. The computer system includes one or more processors 201, memory 202, and mass storage 203, which communicate with each other via a bus 207. The one or more processors 201 may include, for example, one or more central processing units (CPUs) or one or more graphics processing units (GPUs) or both. The computer system may also include other devices such as one or more output devices 204, one or more input devices 205, and one or more peripherals 206. The one or more peripherals 206 may include a modem, a network adapter, or both.

[0056] One or both of the memory 202 and the mass storage 203 include a computer-readable medium storing one or more instruction sets. These instructions may be partially or completely stored in the memory of one or more processors 201. When executed by one or more processors 201, these instructions cause one or more processors 201 to provide the functionality of Near-RT RIC 3, O-CU-CP 4, O-CU-UP 5, or O-DU 6.

[0057] Figure 3 shows an example configuration of O-RU 7. O-RU 7 is typically implemented using dedicated hardware. This dedicated hardware includes a front-haul interface 301, a low PHY processor 302, a DFE circuit 303, and an RF FE circuit 304. The front-haul interface 301 includes an interface circuit for an open front-haul transport. The low PHY processor 302 includes one or more dedicated processors for low PHY signal processing. The one or more dedicated processors may include one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), one or more digital signal processors (DSPs), or any combination thereof. The DFE circuit 303 includes a circuit that performs DFE processing, e.g., DPD, CFR, DUC, and DDC. The RF FE circuit 304 includes, e.g., PAs, LNAs, bandpass filters, DACs, and ADCs.

[0058] However, some of the functions or signal processing of O-RU 7 may operate on COTS hardware. For example, some or all of the low PHY layer signal processing located in O-RU 7 may operate on COTS hardware and may be implemented on a virtualization or cloud platform such as O-Cloud 8.

[0059] Next, several embodiments will be described. Note that the channel prediction function described herein is not limited to using SRS-based channel estimates for channel prediction. More specifically, but not limited to, channel estimates obtained from any method, including but not limited to those obtained from received reference (or pilot) signals, including SRS and uplink DMRS, may be interpreted within the scope of the embodiments. Therefore, the channel prediction function can take historical values ​​of channel estimates obtained from any method, including but not limited to those obtained from received reference signals, including SRS and uplink DMRS, as input. Based on the historical values ​​of the input channel estimates, the channel prediction function can predict new values ​​of the channel estimates. The predicted values ​​of the channel estimates may improve the performance of the communication system under consideration in terms of one or more performance metrics (e.g., system throughput in uplink or downlink transmission).

[0060] <First Embodiment> The configuration example of the wireless communication system according to this embodiment is the same as the configuration example described with reference to Figures 1-3. This embodiment provides details of the arrangement of channel estimation and channel prediction in a base station function split. In this embodiment, channel prediction is arranged in the same logic unit as channel estimation. Specifically, the channel prediction function, operation, processing block, or section is arranged together with the channel estimation function, operation, processing block, or section in O-RU 7, O-DU 6, or Near-RT RIC 3. In other words, in this embodiment, at least one of O-RU 7, O-DU 6, and Near-RT RIC 3 is configured to perform both channel estimation and channel prediction. From the viewpoint of a method of manufacturing the base station system, the method includes manufacturing at least one of O-RU 7, O-DU 6, and Near-RT RIC 3.

[0061] This arrangement, configuration, or manufacturing method eliminates the need for signaling between the channel estimation processing block and the channel prediction processing block to be transmitted over interfaces between different logical units (e.g., OFH C-plane). Therefore, when deploying the channel prediction processing block in a base station system (e.g., gNB), this can suppress the increase in traffic over interfaces between different logical units (e.g., OFH C-plane). In addition, this helps reduce the latency of the control loop, including channel prediction.

[0062] As described above, in one example, channel estimation may be based on one or more received uplink reference (or pilot) signals. In an example of channel estimation, the calculated channel estimation may consist of at least the amplitude and phase of the channel impulse response or channel frequency response. Such amplitude and / or phase may constitute channel characteristics. There may be other channel characteristics that can be estimated by channel estimation. Channel prediction may predict new values ​​of the channel estimation using past channel estimations obtained by channel estimation based on uplink reference signals(s) as its input. As an example, but not an limitation, uplink reference signals(s) may include one or both of the SRS and uplink DMRS.

[0063] As described above, in 5G NR, the SRS is an uplink reference signal set specifically for the UE. The SRS is used by the base station (e.g., gNB, O-DU 6) for UL channel sounding, i.e., uplink channel estimation between the UE and the base station (e.g., O-RU 7, gNB). SRS-based channel estimation involves estimating the channel characteristics between the UE and O-RU 7 using the received result of the SRS transmitted from the UE. In the uplink, the results of SRS-based uplink channel estimation may be used for purposes including, but are not limited to, calculating uplink beamforming weights (e.g., at least one of codebook-type or non-codebook-type beamforming), link adaptation, rank adaptation, channel-dependent scheduling, timing control, and beam management. Furthermore, in downlinks (e.g., downlinks in TDD systems), SRS-based uplink channel estimation may be used for purposes including, but are not limited to, calculating reciprocity-based downlink precoding weights (or beamforming weights) (e.g., at least one of codebook or non-codebook type beamforming), link adaptation, rank adaptation, and channel-dependent scheduling.

[0064] SRS-based beamforming, that is, the calculation of precoding weights or beamforming weights using the results of SRS-based channel estimation, can utilize SRS-based channel prediction. SRS-based channel prediction includes a temporal prediction using the results of SRS-based channel estimation. SRS-based channel prediction may also be a prediction of future channel characteristics using past SRS-based channel estimation results. Alternatively, the temporal prediction may predict eigenvectors for downlink transmission, precoding weights for downlink transmission, beamforming weights for downlink transmission, or downlink beams for downlink transmission. Furthermore, or instead, the temporal prediction may predict beamforming weights for uplink transmission. Such temporal predictions may be performed by performing inference in a trained artificial intelligence or machine learning model.

[0065] Referring to Figures 4A-4H, SRS-based channel estimation, channel prediction, and eigenvector prediction will be explained with specific examples. Although these examples use SRS as the reference signal, they can be extended to channel prediction based on uplink DMRS-based channel estimation.

[0066] As shown in Figures 4A and 4B, a wireless communication system consists of multiple communication devices, each capable of communicating with other communication devices, such as a base station (BS) or access point. For simplicity, we assume that the BS device 400 can communicate with multiple UE terminals 460, including two UE terminals UE#1 and UE#2. UE terminals UE#1 and UE#2 are located within a radio coverage area (e.g., cell) 480 formed by the BS device 400, allowing each UE terminal to perform uplink (UL) transmissions and enabling the BS device 400 to perform downlink (DL) transmissions using beamforming. UL transmissions may also use beamforming.

[0067] In Figure 4C, the UE terminal 460 transmits uplink SRS (UL-SRS) to the BS device 400 at 40-millisecond (ms) intervals. Each time the BS device 400 receives an UL-SRS, it performs channel estimation 401, 402, or 403, thereby calculating at least one of digital beamforming (BF) weights, such as uplink beamforming weights or downlink beamforming weights. The SRS-based channel estimation method may include at least one of the following: least squares (LS) channel estimation algorithm, linear minimum mean square error (MMSE) channel estimation algorithm, discrete Fourier transform (DFT)-based channel estimation algorithm, discrete cosine transform (DCT)-based channel estimation algorithm, or other channel estimation algorithms. In the example of channel estimation, the amplitude and phase of the channel impulse response may be calculated.

[0068] The radio channel between the BS device 400 and the UE terminal 460 may fluctuate over time due to the movement of the UE terminal 460 or other reasons contributing to radio channel variations. If the state of the radio channel between the BS device 400 and the UE terminal 460 changes within a 40ms duration between t=0 (a time instance in which the UE terminal 460 transmits UL-SRS#1 and the BS device 400 receives it) and t=40ms (a time instance in which the UE terminal 460 transmits UL-SRS#2 and the BS device 400 receives it), the BS device 400 may not have an accurate understanding of the channel response between t=0 and t=40ms. The phenomenon in which estimated channel responses become outdated or inaccurate over time due to various factors (e.g., user mobility or environmental changes) is sometimes called channel aging. In such situations, the BS device 400 may have to reuse the beamforming weights calculated in the previous channel estimation event until the next channel estimation event. For example, BS device 400 might calculate channel estimates and beamforming weights at t=0 and continue using the same beamforming weights for downlink transmission until the next channel estimation event occurs at t=40ms. As a result, the use of older channel estimation results and digital beamforming weights by BS device 400 can lead to performance degradation (e.g., throughput) caused by factors such as inefficient interference cancellation between spatially multiplexed streams and interference between signals destined for different UE terminals.

[0069] Figure 4C illustrates an example of channel estimation based on uplink SRS, but channel estimation can be based on another type of reference signal, such as uplink DMRS, in another example. In such an example, UE terminal 460 can transmit uplink DMRS to BS device 400 during an uplink transmission, such as a PUSCH or PUCCH transmission. BS device 400 then extracts the uplink DMRS symbols frequency-multiplexed with data symbols in the PUSCH or PUCCH transmission, performs channel estimation based on the uplink DMRS, and uses it to calculate at least one of the uplink beamforming weights and downlink beamforming weights until the next channel estimation event. The effects of channel changes over time can degrade the system's throughput performance.

[0070] Referring to Figure 4D, an example of channel prediction that can improve the performance (e.g., throughput performance) of a system employing SRS-based channel estimation is illustrated. Here, the BS device 400 performs channel estimation 401 and 402 based on the received SRS from the UE terminal 460 at times t1=0 and t2=40ms, similar to Figure 4C. Next, the BS device 400 performs channel prediction 404 and computes the predicted channel response based on the estimated channel response.

[0071] For example, if UL-SRS#2 is received at time instance t2, the BS instrument 400 calculates the channel response at time instances t21, t22, ... based on two or more channel responses obtained by channel estimation (e.g., 401 and 402). If UL-SRS#3 is received at time instance t3, the BS instrument 400 performs channel prediction 405 again in the same manner. Extrapolation can be performed by at least one extrapolation method such as linear extrapolation, linear regression, least squares estimation, nonlinear regression, polynomial regression, spline regression, curve fitting, or by performing inference with a trained artificial intelligence or machine learning model. The example in Figure 4D can also be applied to an example employing uplink DMRS-based channel estimation.

[0072] Referring to Figure 4E, an example of channel prediction is described from the perspective of signal processing for precoding based on eigenvector decomposition (EVD) or singular value decomposition (SVD). The channel response matrix is ​​predicted in time slots where channel estimation is not performed. Subsequently, SVD or EVD operations are performed to obtain eigenvectors, which are used for beamforming. For example, BS device 400 can receive the first uplink SRS (SRS #1) in time slot = 0 and the second SRS (SRS #2) in time slot = 40 ms. Therefore, channel estimation can be performed in time slots = 0 and 40 ms to obtain the corresponding estimated channel response matrices 451 and 452 for time slots = 0 and 40 ms, respectively. Now, consider the case where an SRS is received in time slot = 80 ms (not shown in Figure 4E), and the next channel estimation will be performed. In this case, for time slots greater than 40ms and less than 80ms, the channel response matrix is ​​predicted (as described above) to reduce performance degradation due to channel changes over time.

[0073] More specifically, based on two historical channel response matrices 451 and 452 obtained by channel estimation operations at time slots 0 and 40 ms, channel response matrices 453 at time slots 41 ms, 42 ms, ..., 79 ms can be predicted. Then, at least one of SVD or EVD operations can be performed on the predicted channel matrix at each of the time slots 41 ms, 42 ms, ..., 79 ms. Then, a beamforming matrix can be created using the eigenvectors or singular vectors of the obtained channel matrix. As a result, precoded beamforming transmission becomes possible at time slots 41 ms, 42 ms, ..., 79 ms. Therefore, a channel prediction method as shown in the example in Figure 4E may require at least one of SVD or EVD operations at all time slots where channel prediction is performed, specifically at time slots 41 ms, 42 ms, ..., 79 ms. However, SVD or EVD operations can be complex. Therefore, in some examples, it may be desirable to reduce the number of SVD or EVD operations.

[0074] In some cases, the number of SVD or EVD calculations can be reduced by directly predicting the eigenvectors of the channel response matrix in the time instances where channel prediction is desired. This is illustrated with an example in Figure 4F. Specifically, referring to Figure 4F, instead of predicting the channel response matrix for each downlink transmission time slot, the eigenvectors (454) are directly predicted. Therefore, the need to perform complex SVD or EVD calculations for each downlink transmission time slot where channel estimation is not performed can be avoided. Thus, SVD or EVD calculations only need to be performed in the channel estimation time slots (time slots = 0 and 40ms in Figure 4F). Then, using the eigenvectors obtained at time slots = 0 and 40ms, eigenvector 454 (or its corresponding beamforming matrix) can be directly predicted at time slots = 41ms, 42ms, 43ms, 44ms, etc. In this way, by directly predicting eigenvectors instead of predicting the pure (raw) channel matrix, the total number of SVD or EVD calculations between two channel estimation instances can be significantly reduced, thereby lowering the overall complexity of the system.

[0075] Referring to Figure 4G, the functional configuration of the BS device 400, including an SRS-based channel estimator and channel predictor, is described. The BS device 400 has an array antenna consisting of M antennas 410_1 to 410_M, where M is an integer greater than or equal to 1. Antennas 410_1 to 410_M are connected to radio transceivers (TRs) 420_1 to 420_M, respectively. Each radio transceiver 420 includes a Radio Frequency (RF) front end 421, a fast Fourier transform (FFT) section 422, and an inverse FFT (IFFT) section 423. The RF front end 421 receives the RF received signal from the corresponding antenna and outputs the received data sequence to the FFT section 422. The RF front end 421 receives the transmitted data sequence from the IFFT section 423 and outputs the RF transmitted signal to the corresponding antenna. The FFT section 422 decomposes the received data sequence into frequency components. Section 423 of the IFFT constructs the transmit data sequence from the frequency components.

[0076] The BS device 400 further includes a channel estimator 431, a channel predictor 432, and a precoder 433. The channel estimator 431 takes the frequency components of the UL-SRS from the FFT section 422 of each radio transceiver as input and outputs channel estimation signals to the channel predictor 432. The channel predictor 432 predicts the channel response in time instances where channel estimation is not performed, based on one or more past channel responses, as described above (see, for example, Figures 4D and 4E). The channel predictor 432 outputs the predicted channel responses to the precoder 433.

[0077] The BS device 400 further includes a scheduler 434 and several data processing sections, including a data generator 435, a forward error correction (FEC) section 436, a modulator 437, and a resource mapper 438. The scheduler 434 determines which users to schedule for DL ​​transmission in a given time slot. The data generator 435 generates the transmission data, which is then FEC-corrected in the FEC section 436. The modulator 437 modulates the output of the FEC section 436 to output the modulated transmission data to the resource mapper 438. The resource mapper 438 performs resource mapping of the transmission data to output frequency components to the IFFT section 423 of each transceiver via the precoder 433. The precoder 433 performs precoding according to the estimated and / or predicted channel responses received from the channel estimator 431 and / or channel predictor 432. As mentioned above, channel prediction can be performed for future time slots, and the predicted channel response is stored in memory. Alternatively, channel prediction can be performed in real time for each time slot.

[0078] The functions shown by reference numbers 431-438 in Figure 4G may be performed by one or more processors and / or one or more central processing units (CPUs) that execute programs stored in program memory 440. The programs include a channel prediction program capable of performing the functions of the channel predictor 432. In Figure 4G, the functional configuration of the BS device 400 is explained using SRS as an example of a reference signal, but other reference signals besides SRS, such as demodulated reference signals (DMRS), may also be used for channel estimation.

[0079] Furthermore, with reference to Figure 4H, the functional configuration of the BS device 400, including the eigenvector predictor, will be described. All other functional blocks in Figure 4H are the same as those described above in Figure 4G. The eigenvector predictor 439 predicts the eigenvectors of the channel response in time instances where beamforming is desired but channel estimation is not performed, from two or more past eigenvectors (see, for example, Figure 4F). The eigenvector predictor 439 outputs the predicted eigenvectors to the precoder 433.

[0080] Apart from the channel prediction and eigenvector prediction methods described herein, other methods may exist that predict at least one parameter related to channel state information (CSI) between a base station and a UE, which may be interpreted within the scope of this disclosure. In some examples, the UE can predict future CSI and transmit it to the base station. In some examples, the base station can predict future CSI based on the feedback received. In one-sided time-domain CSI prediction, the prediction model can be implemented solely on the UE side. Such methods can largely reuse existing CSI frameworks. In addition to CSI prediction, other techniques may be considered, including but not limited to the prediction of channel quality indicators (CQI), rank indicators (RI), precoding matrix indicators (PMI), signal-to-noise-plus-interference ratios (SINR), Doppler shift, path loss, angle of arrival (AoA), and angle of departure (AoD). In some cases, various machine learning models can be used for artificial intelligence (AI) / machine learning (ML) based CSI prediction.Such AI / ML models include recurrent neural networks (RNNs), long short-term memory (LSTM) networks, convolutional neural networks (CNNs), transformer models, multi-layer perceptron (MLP) mixers, fully convolutional networks (FCNs), or auto-regression models to predict future CSIs based on past and present channel information. In addition, some examples may use non-AI / ML-based prediction methods, including at least one of the sample-and-hold method, Wiener filter method, Kalman filter method, Berg method, or Yule-Walker method.

[0081] Apart from SRS-based channel estimation, base station equipment (BS) can also perform channel estimation using DMRS. DMRS is a type of reference signal used in communication systems such as 5G NR. DMRS can be transmitted both uplink and downlink. One application of DMRS is to facilitate channel estimation at the receiver, enabling at least one of the operations of equalization and demodulation. Furthermore, the channel estimate obtained from DMRS can be used for beamforming, such as uplink beamforming and downlink beamforming.

[0082] Consider an example of an uplink DMRS-based channel estimation method when a BS device receives uplink DMRS from an UE during PUSCH or PUCCH transmission. Specifically, the DMRS symbols may be frequency-multiplexed with PUSCH / PUCCH data symbols. The DMRS may be configured as front-loaded (pre-DMRS) and additional DMRS symbols. The BS device can then extract the uplink DMRS from the received signal (e.g., the received PUSCH signal) and compare it to a known reference signal. In this way, radio channel characteristics such as fading can be estimated, which includes how the signal changes during transmission. More specifically, the BS device can perform uplink channel estimation using the received uplink DMRS by employing at least one of the following channel estimation algorithms, e.g., least squares (LS) channel estimation algorithm, linear least mean squares error (MMSE) channel estimation algorithm, discrete Fourier transform (DFT) based channel estimation algorithm, discrete cosine transform (DCT) based channel estimation algorithm, or any other channel estimation algorithm.

[0083] For example, uplink DMRS symbols may be transmitted by frequency multiplexing with data symbols on resource blocks (RBs) where uplink data transmissions are scheduled. In other words, such DMRS-based channel estimation may only be possible on RBs on the uplink portion of an uplink slot or special slot selected by the scheduler for PUSCH transmissions. Therefore, DMRS-based channel estimation methods may have limited flexibility in performing channel estimation on any desired frequency (e.g., RB) across the entire channel.

[0084] In contrast, SRS-based channel estimation methods can offer greater flexibility in sounding (and estimating) any frequency subcarrier (or, e.g., RB) across the entire channel. Therefore, SRS-based channel estimation may be independent of PUSCH or PUCCH transmit scheduling, i.e., PUSCH / PUCCH transmit RBs and PUSCH / PUCCH transmit uplink slots. The BS device can configure or reconfigure SRS transmission from the UE on any desired RB (e.g., all channels or all RBs, a specific group of RBs, etc.) on the uplink portion of an uplink slot or special slot, providing greater flexibility in estimating any portion of the channel bandwidth. Such SRS configuration can be performed in at least one of periodic, aperiodic, or semi-persistent ways.

[0085] SRS can be configured using RRC signaling. For example, a BS device can use RRC signaling to send SRS configuration parameters to a UE. Periodic SRS is transmitted periodically from the UE to the BS device based on the SRS configuration parameters. Non-periodic SRS can be dynamically triggered by the BS using downlink control information (DCI) or other signaling methods. Furthermore, semi-persistent SRS is transmitted periodically, similar to periodic SRS, but can be dynamically activated or deactivated using medium access control (MAC) control elements (CEs) or other signaling methods. The configurable parameters of the SRS that the BS device determines for each UE may include at least one of the following: the number of SRS ports, time-domain location, frequency-domain location, bandwidth, cyclic shift, transmit comb, and offset.

[0086] In one or more of the examples described above, the longer the time between channel estimation (based on SRS or uplink DMRS) and beamforming (uplink or downlink), the more likely the quality of channel estimation will deteriorate due to the effects of channel aging. More specifically, if channel estimates obtained from received SRS or uplink DMRS are used to calculate uplink or downlink beamforming weights, the quality of signal transmission or reception may deteriorate. This is because accurate channel status information (CSI) is crucial for effective beamforming and / or precoding in massive MIMO systems, for example, in 5G and beyond communications. As previously explained, an effective approach to solving the problem of channel aging may be channel prediction or eigenvector prediction.

[0087] In examples where uplink DMRS-based channel estimation is used for equalizing and demodulating uplink data symbols, such as demodulating data symbols transmitted in the same time slot as DMRS symbols, the effects of channel time-dependent changes may not be present because the data symbols and DMRS symbols are received in the same time slot. However, there may be applications where DMRS-based channel estimation benefits from channel prediction or eigenvector prediction. For example, if DMRS-based channel estimates are used in a later time slot (i.e., a time slot later than when the uplink DMRS was received) (e.g., when performing downlink beamforming in a later slot), channel time-dependent changes may affect the channel estimates, and actions such as channel prediction or eigenvector prediction may be needed to mitigate channel time-dependent changes.

[0088] Specific examples of the configuration of SRS-based channel estimation and SRS-based channel prediction are shown below with reference to Figures 5A to 5F. Figures 5A to 5F show the configuration of processing blocks related to downlink transmission (e.g., PDSCH transmission) by the base station.

[0089] As described above, according to the current O-RAN technical specifications, SRS-based channel estimation is placed in the O-DU (see, for example, section 4.2 of Non-Patent Document 1). Therefore, in this case, as shown in Figure 5A or Figure 5B, the SRS-based channel prediction 522 may be placed in the O-DU 6 together with the SRS-based channel estimation 521.

[0090] Figure 5A shows a configuration in which Category A O-RU, i.e., precoding 504, is located in O-DU 6. In the example in Figure 5A, O-DU 6 includes a scheduler 501, coding, scrambling and modulation 502, layer mapping 503, precoding 504, and RE mapping 505. O-DU 6 further includes SRS-based channel estimation 521 and SRS-based channel prediction 522. O-RU 7 includes DL beamforming 506 and IFFT and CP addition 507. Placing SRS-based channel estimation 521, SRS-based channel prediction 522, and precoding 504 in the same logical unit, i.e., O-DU 6, helps reduce the control loop latency required for calculating precoding weights. This can contribute to improved performance, especially in environments with many highly mobile UEs.

[0091] On the other hand, Figure 5B shows an example where Category B O-RU, i.e., precoding 504, is placed in O-RU 7. In the example in Figure 5B, O-DU 6 includes a scheduler 501, coding, scrambling and modulation 502, layer mapping 503, and RE mapping 505. O-DU 6 further includes SRS-based channel estimation 521 and SRS-based channel prediction 522. O-RU 7 includes precoding 504, DL beamforming 506, and IFFT and CP addition 507.

[0092] Instead of the configurations shown in Figures 5A and 5B, the configuration shown in Figure 5C may be adopted. In the example of Figure 5C, the SRS-based channel prediction 522 is located in O-RU 7 together with the SRS-based channel estimation 521. Furthermore, in the example of Figure 5C, the precoding 504 is located in O-RU 7. As described above, SRS-based beamforming, i.e., the calculation of downlink precoding weights or beamforming weights using the results of SRS-based channel estimation, requires SRS-based channel prediction for performance improvement. Placing the SRS-based channel estimation 521, SRS-based channel prediction 522, and precoding 504 in O-RU 7 helps reduce the control loop latency required for calculating precoding weights. This can contribute to performance improvement, especially in environments with many highly mobile UEs. In addition, since the precoding 504 is located in O-RU 7 in Figure 5C, the configuration in Figure 5C has the advantage of reducing fronthaul capacity compared to the configuration in Figure 5A.

[0093] In the example shown in Figure 5C, the O-DU 6 may also have an SRS-based channel estimate 521 and an SRS-based channel prediction 522, as indicated by the dotted line in Figure 5C. The results of the SRS-based channel estimate 521 and / or the SRS-based channel prediction 522 located in the O-DU 6 may be used for link adaptation and scheduling for uplinks. Alternatively, they may be used for link adaptation and scheduling for downlinks.

[0094] For example, SRS-based channel estimation and SRS-based channel prediction can be implemented in both O-RU7 and O-DU6, and can be optionally enabled in either O-RU7 or O-DU6. The activation of such options (or conditions) for SRS-based channel estimation and SRS-based channel prediction in either O-RU7 or O-DU6 may be determined based on one or more conditions or criteria. For example, one or more conditions may be based on or related to one or any combination of OFH traffic, latency, capacity, etc. The decision to enable SRS-based channel estimation and SRS-based channel prediction in either O-RU7 or O-DU6 may be based on a comparison of one or more parameters, such as OFH traffic, latency, and capacity, with one or more thresholds. More specifically, if at least one of OFH traffic, latency, and capacity is less than or greater than a threshold, SRS-based channel estimation and SRS-based channel prediction may be enabled in O-RU7. Otherwise, SRS-based channel estimation and SRS-based channel prediction may be enabled in O-DU6. Other conditions for determining whether to enable or disable at least one of SRS-based channel estimation and SRS-based channel prediction in O-RU7 may be considered within the scope of this disclosure. For example, there may be a controller (e.g., Near-RT RIC3 or Non-RT RIC2) that performs a decision on whether to enable the channel estimation and channel prediction functions in O-DU6 or O-RU7 based on at least one predetermined condition. Figure 5D shows controller 530, which is an example of the controller described above.

[0095] Instead of the configurations shown in Figures 5A-5C, the configurations shown in Figure 5E or 5F may be adopted. In the examples of Figures 5E and 5F, the SRS-based channel estimation 521 and SRS-based channel prediction 522 are located in Near-RT RIC 3. The difference between Figure 5E and Figure 5F is that in Figure 5E, precoding 504 is located in O-DU 6, whereas in Figure 5F, precoding 504 is located in O-RU 7. In the configurations shown in Figures 5E and 5F, signaling between the SRS-based channel estimation 521 and SRS-based channel prediction 522 takes place within Near-RT RIC 3. Therefore, these configurations may help to some extent in suppressing the increase in traffic on the interfaces between logical units. However, considering that it is necessary to calculate precoding weights using the results of SRS-based channel prediction 522, the advantages of suppressing control latency and reducing control traffic on the interfaces between logical units obtained by the configurations of Figure 5C or 5A will likely be greater.

[0096] <Second Embodiment> The configuration example of the wireless communication system according to this embodiment is similar to the configuration example described with reference to Figures 1-3. This embodiment provides details of the arrangement of the dynamic uplink SRS resource allocation processing block and the signaling between the dynamic uplink SRS resource allocation processing block and the scheduling processing block in a base station function split. The scheduling processing block may be responsible for allocating resources (e.g., RBs) to each UE for at least one of uplink transmission and downlink transmission. In other words, the scheduling processing block includes one or both of an uplink scheduling processing block (or scheduler) and a downlink scheduling processing block (or scheduler).

[0097] The dynamic uplink SRS resource allocation processing block dynamically determines the uplink SRS resources (e.g., period, frequency, REs, RBs, hopping) to allocate to the UE. Increasing the amount of SRS resources allocated to the UE helps reduce performance degradation due to channel aging, but it also leads to an increase in communication overhead. Therefore, the dynamic uplink SRS resource allocation processing block adaptively determines the uplink SRS resources to allocate to the UE based on the channel state (or condition) of that UE.

[0098] The dynamic uplink SRS resource allocation processing block may utilize the results of either or both channel estimation and channel prediction. Therefore, the dynamic uplink SRS resource allocation processing block may be located in the same logical unit (e.g., O-DU 6 or O-RU 7) as either or both of the channel estimation processing block and the channel prediction processing block.

[0099] For example, channel estimation and channel prediction may be SRS-based channel estimation and channel prediction, or uplink DMRS-based channel estimation and channel prediction, determining the channel state (or state) of each UE so that uplink SRS resource allocation can be performed based on its channel state (or state). Thus, in one example, the dynamic uplink SRS resource allocation processing block may be located in the same logical unit (e.g., O-DU6 or O-RU7) as either one or both of the SRS-based channel estimation processing block and the SRS-based channel prediction processing block. Furthermore or alternatively, the dynamic uplink SRS resource allocation processing block may be located in the same logical unit (e.g., O-DU6 or O-RU7) as either one or both of the uplink DMRS-based channel estimation processing block and the uplink DMRS-based channel prediction processing block.

[0100] This can reduce traffic increases on interfaces between different logical units (e.g., OFH C-plane) when a dynamic uplink SRS resource allocation processing block is introduced into a base station system (e.g., gNB). In some examples, the dynamic uplink SRS resource allocation processing block can retrieve information about the UE status from the channel estimation block at periodic or aperiodic intervals and dynamically modify the uplink SRS resource allocation based on the received information.

[0101] Furthermore, or alternatively, the dynamic uplink SRS resource allocation processing block may be located in the same logical unit (e.g., O-DU 6) as the uplink and / or downlink scheduling processing blocks. This arrangement facilitates the use of the results of dynamic uplink SRS resource allocation for one or both of the uplink and downlink scheduling. For example, a downlink scheduler can allocate at least one of the PDCCH transmit resources and PDSCH transmit resources to a UE around (e.g., adjacent to) the SRS resources allocated to that UE. More specifically, in one example, the RB most recently received on the uplink from the UE may have the most accurate CSI. Therefore, if information regarding dynamic uplink SRS resource allocation is shared with the uplink scheduling processing block and / or downlink scheduling processing block, the uplink scheduling processing block and / or downlink scheduling processing block can allocate such RBs in subsequent uplink (or downlink) time slots for imminent uplink (or downlink) signal transmissions. For example, a PDSCH transmission to a UE may be scheduled on the same RB that received the SRS in the downlink time slot immediately following the SRS reception. Similarly, a PUSCH transmission from a UE may be scheduled on the same RB that received the SRS in the uplink time slot immediately following the SRS reception. Downlink beamforming and / or uplink beamforming that takes into account the channel condition estimated or predicted from the SRS reception result can contribute to improving the performance of PDSCH and / or PUSCH transmissions.

[0102] Alternatively, this arrangement facilitates the use of the results of uplink and / or downlink scheduling for dynamic uplink SRS resource allocation. For example, a dynamic uplink SRS resource allocation processing block may allocate uplink SRS transmit resources for a UE around (e.g., immediately before) PDSCH resources allocated to that UE, thereby potentially improving PDSCH transmit performance. Similarly, a dynamic uplink SRS resource allocation processing block can allocate uplink SRS transmit resources for a UE around (e.g., immediately before) PUSCH resources allocated to that UE, thereby potentially improving PUSCH transmit performance.

[0103] More specifically, in a downlink example, the dynamic uplink SRS resource allocation processing block can obtain information about PDSCH scheduling for a particular UE from the downlink scheduler. Then, based on this information about PDSCH scheduling for the UE, the dynamic uplink SRS resource allocation processing block can determine the allocation of SRS resources to that UE. In other words, the RB and / or time slots on which SRS transmission from that UE should be scheduled are determined based on their imminent PDSCH schedule. This method ensures that accurate CSI is obtained at RBs where downlink signal transmission is desired. Furthermore, this method can also prevent unnecessary channel estimation at RBs where downlink signal transmission is not scheduled, thereby reducing pilot (reference signal) overhead and creating opportunities for data transmission.

[0104] It should be noted that the examples described herein illustrate only a few typical scenarios of performance improvements based on information exchanged between the uplink and / or downlink scheduler and the dynamic uplink SRS resource allocation processing block. However, all possible scenarios in which the uplink and / or downlink scheduler and the dynamic uplink SRS resource allocation processing block may exchange information (either unidirectionally or bidirectionally) for the improvement of at least one performance metric in the communication system should be interpreted within the scope of this disclosure.

[0105] In this disclosure, a scheduler responsible for at least one of uplink scheduling and downlink scheduling (e.g., PUSCH scheduling, PUCCH scheduling, PDSCH scheduling, or PDCCH scheduling) can exchange information with a dynamic uplink SRS resource allocation processing block. In an example of a 5G NR system, downlink scheduling may be performed by dynamic scheduling and at least one of semi-persistent scheduling. Similarly, uplink scheduling is performed by dynamic scheduling and at least one of semi-persistent scheduling. Semi-persistent scheduling is sometimes referred to as configured scheduling or configured grant operations, particularly in the case of uplinks.

[0106] More specifically, in dynamic downlink scheduling, PDSCH scheduling may be performed using PDCCH, and for example, the BS (e.g., gNB) may notify the UE about PDSCH scheduling and grants using DCI (DCI 1_0 or DCI 1_1, etc.). In one example, a PDSCH transmission is performed after the K0 slot of a PDSCH grant. By using such dynamic scheduling with DCI, the BS can change scheduling parameters for each transmission to adapt to the state of the radio link, for example. In downlink semi-persistent scheduling, PDSCH transmissions are scheduled using RRC signaling. Thus, based on information exchanged between the dynamic uplink SRS resource allocation processing block and the downlink scheduler, the BS can determine PDSCH resource allocations and notify the UE using DCI, RRC signaling, or at least one of other signaling methods.

[0107] In dynamic uplink scheduling, each push transmission may be scheduled using DCI (such as DCI 0_0 or DCI 0_1). In uplink semi-persistent scheduling, instead of using DCI for each push transmission, RRC signaling can be used to schedule push transmissions, reducing the load on the PHY / MAC scheduling process. Therefore, based on the information exchanged between the dynamic uplink SRS resource allocation processing block and the uplink scheduler, the BS can determine the push resource allocation and notify the UE using DCI, RRC signaling, or at least one of the other signaling methods.

[0108] As can be understood from the above explanation, in some implementations, the dynamic uplink SRS resource allocation processing block may be located in a different logical block from the uplink / downlink scheduling processing block. Figures 6A and 6B show examples of the placement of the dynamic uplink SRS resource allocation processing block and signaling between the dynamic uplink SRS resource allocation processing block and the scheduling processing block. In Figures 6A and 6B, the scheduler 601 is located in O-DU 6, and the dynamic uplink SRS resource allocation 602 is located in O-RU 7 or O-CU-CP 4.

[0109] As described above, the scheduler 601 performs either or both uplink scheduling and downlink scheduling for one or more UEs. The dynamic uplink SRS resource allocation 602 dynamically determines the uplink SRS resources (e.g., period, frequency, REs, RBs, hopping) to be allocated to a UE. The dynamic uplink SRS resource allocation 602 adaptively determines the uplink SRS resources to be allocated to a UE based on the channel state (or status) of that UE.

[0110] In the example shown in Figure 6A, the dynamic uplink SRS resource allocation 602 sends information to the scheduler 601 indicating the dynamically determined uplink SRS resource allocation to the UE. The scheduler 601 receives this information from the dynamic uplink SRS resource allocation 602. The scheduler 601 may use the received information to determine the uplink resources (e.g., PUSCH resources) and / or downlink resources (e.g., PDSCH resources) to be allocated to the UE.

[0111] The scheduler 601 or O-DU 6 (e.g., OFH C-plane termination) may request O-RU 7 or O-CU-CP 4 to transmit information indicating uplink SRS resource allocation. The dynamic uplink SRS resource allocation 602 may transmit information indicating uplink SRS resource allocation in response to a request from the scheduler 601 or O-DU 6 (e.g., OFH C-plane termination). Alternatively, the dynamic uplink SRS resource allocation 602 may autonomously transmit information indicating uplink SRS resource allocation to the scheduler 601 or O-DU 6 (e.g., OFH C-plane termination) in response to an update of the uplink SRS resource allocation.

[0112] The dynamic uplink SRS resource allocation 602 may transmit information indicating uplink SRS resource allocation to the scheduler 601 or O-DU 6 (e.g., OFH C-plane terminal) via control plane messages on the fronthaul interface (e.g., OFH, LLS). The format of these control messages may be the same as one of the existing formats or a newly defined format.

[0113] In the example in Figure 6B, the scheduler 601 sends information to the dynamic uplink SRS resource allocation 602 indicating one or both of the uplink resource allocation and / or downlink resource allocation to the UE. This information may indicate one or both of the dynamic uplink resource allocation and / or dynamic downlink resource allocation to the UE, or one or both of the semi-persistent (or configured) uplink resource allocation and / or semi-persistent (or configured) downlink resource allocation to the UE. The dynamic uplink SRS resource allocation 602 receives this information from the scheduler 601. The dynamic uplink SRS resource allocation 602 may use the received information to determine the uplink SRS resource allocation to the UE.

[0114] The scheduler 601 may transmit information indicating one or both of the dynamic uplink resource allocation and / or downlink resource allocation to the dynamic uplink SRS resource allocation 602 or O-RU 7 (e.g., OFH C-plane termination) via a control plane message on the fronthaul interface (e.g., OFH, LLS). The format of this control message may be the same as one of the existing formats or a newly defined format.

[0115] The transmission of information indicating uplink SRS resource allocation, as described with reference to Figure 6A, and the transmission of information indicating uplink and / or downlink resource allocation, as described with reference to Figure 6B, may be performed in combination.

[0116] <Third Embodiment> The configuration example of the wireless communication system according to this embodiment is the same as the configuration example described with reference to Figures 1 to 3. This embodiment provides details of information exchange between O-DU and O-RU for one or more purposes described in this disclosure, including the first and second embodiments.

[0117] For example, information exchange between O-DU6 and O-RU7 for one or more purposes described herein can be implemented using a "Section Extension." In another example, a new message format, such as a new control plane (C-Plane) message, can be used.

[0118] In the O-RAN context, a "Section" is a basic unit that defines one or more characteristics of data that may be transmitted or received, for example, in the context of a user plane (U-Plane) or C-Plane. Therefore, Sections can be used to structure and organize data transmission between O-DU6 and O-RU7. A typical Section may include information and fields such as Section Type, Section ID, Time Reference, Beam Information, Resource Block Information, IQ Data (for U-Plane), and Control Information (for C-Plane). A C-Plane can have the following six section types: Section types 0, 1, 3, 5, 6, and 7. A U-Plane can have the following four section types: Section types 1, 3, 5, and 6. By using Section Extensions, additional data beyond the standard Section fields can be included, giving the data structure extensibility and flexibility and supporting additional functionality.

[0119] As an example, the architecture proposed in Figure 4C can be implemented using the new C-Plane messages shown in Figures 7A and 7B. More specifically, in an example where SRS-based channel estimation and channel prediction units can be enabled in O-RU7, such C-Plane messages can be used to send specific instructions from O-DU6 to O-RU7. The new section type X is used for delivering SRS-related information from O-DU6 to O-RU7, where "X" is a general placeholder for the new section. The new section can specify SRS setup information such as sequence group number (p), sequence number (q), cyclic shift (cs), resource element (RE) level offset (reoff), transmit comb (comb) type (ct), repetition index (repId), and repetition factor (repFac).

[0120] Furthermore, Figure 7C shows another example of a message, which can be used in combination with or separately from Figures 7A and 7B. For example, as shown in Figure 7C, SRS configuration parameters such as bandwidth, frequency allocation, periodicity, comb size, and cyclic shift may be specified. Next, channel estimation settings such as estimation method, channel estimation granularity in the frequency domain, and correspondence and size of the averaging window may be specified. The channel estimation settings may include channel estimation granularity in the frequency domain. The channel estimation settings may include the type and size of the averaging window. Next, channel prediction settings such as prediction method, AI / ML or non-AI / ML, and prediction horizon may be specified. The prediction method may be specified from a predefined list of prediction methods. Next, the requested prediction output may be specified, such as CSI flag, CQI flag, eigenvector flag, SINR flag, RI flag, PMI flag, AoA flag, and AoD flag.

[0121] Figures 7A to 7C show a simple example for implementing C-Plane message exchange in one embodiment of the present disclosure. However, there are various ways to implement C-Plane message exchange, such as using Section Extension as described above. For example, in another example, at least one of the "exDataSize" and "exData" fields of the O-RAN library may be used for information exchange between O-DU6 and O-RU7 for one or more purposes described in the present disclosure.

[0122] The embodiments described above are merely examples of how the technical concept obtained by the present inventor can be applied. In other words, the technical concept is not limited to the embodiments described above, and various modifications are possible.

[0123] For example, some or all of the embodiments described above may also be described as follows, but are not limited to. Some or all of the elements (e.g., configuration and function) described in the appendix directed to the apparatus may also be described as appendixes directed to the method and program. For example, some or all of the elements described in appendixes 15-24, which are dependent on appendix 14, may also be described as appendixes dependent on appendix 25, by a similar dependency relationship to appendix 15-24. As another example, some or all of the elements described in appendixes 35-41, which are dependent on appendix 34, may also be described as appendixes dependent on appendix 42 or 43, by a similar dependency relationship to appendix 35-41. Some or all of the elements described in any appendix may be applied to various hardware, software, recording means, systems, and methods for recording software.

[0124] (Note 1) A Radio Unit (RU) configured to perform lower physical layer signal processing, A Distributed Unit (DU) configured to perform upper-level physical layer signal processing, A controller configured to perform near real-time control of wireless access network elements and resources, including at least the aforementioned DU, Equipped with, At least one of the RU, DU, and controller is configured to perform both channel estimation and channel prediction. Base station system. (Note 2) The one configured to perform the channel estimation and channel prediction is the RU. The base station system described in Appendix 1. (Note 3) The RU is further configured to perform precoding for downlink transmission. The base station system described in Appendix 2. (Note 4) The RU is configured to perform the precoding using the channel prediction results. The base station system described in Appendix 3. (Note 5) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The controller is a Near-Real-Time RAN Intelligent Controller compliant with the O-RAN technical specifications. A base station system as described in any one of the appendices 1 to 4. (Note 6) The channel estimation includes estimating the channel characteristics between the User Equipment (UE) and the RU using the reception result of at least one of the Sounding Reference Signal (SRS) and Uplink Demodulation Reference Signal (DMRS) transmitted from the UE. The channel prediction includes a temporal prediction of the channel characteristics, eigenvectors for downlink transmission to the UE, precoding weights for downlink transmission, beamforming weights for downlink transmission, or downlink beam for downlink transmission, using the results of the channel estimation. A base station system as described in any one of the appendices 1 to 5. (Note 7) The DU is configured to schedule either or both uplink and downlink resources, and to perform dynamic uplink Sounding Reference Signal (SRS) resource allocation. A base station system as described in any one of the appendices 1 to 6. (Note 8) The DU is configured to schedule either or both uplink and downlink resources, and to receive information from the RU or Central Unit (CU) indicating the uplink Sounding Reference Signal (SRS) resource allocation dynamically determined by the RU or CU. A base station system as described in any one of the appendices 1 to 6. (Note 9) The DU is configured to request the RU or CU to transmit the information indicating the uplink SRS resource allocation. The base station system described in Appendix 8. (Note 10) The RU is configured to autonomously send the information indicating the uplink SRS resource allocation to the DU in response to an update of the uplink SRS resource allocation. The base station system described in Appendix 8. (Note 11) The DU is configured to receive the information indicating the uplink SRS resource allocation from the RU via control plane messages in the fronthaul interface between the DU and the RU. A base station system as described in any one of the items 8 to 10 of the appendices. (Note 12) The DU is configured to schedule either or both uplink and downlink resources, and to send information indicating resource allocation to User Equipment (UE) to the RU or Central Unit (CU) that performs dynamic uplink Sounding Reference Signal (SRS) resource allocation. A base station system as described in any one of the appendices 1 to 6. (Note 13) The DU is configured to send the information indicating the resource allocation to the RU via control plane messages in the fronthaul interface between the DU and the RU. The base station system described in Appendix 12. (Note 14) Means for performing lower physical layer signal processing, A means for communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a front-haul interface, Means for performing channel estimation and channel prediction, A Radio Unit (RU) equipped with [this feature]. (Note 15) It further includes means for performing precoding for downlink transmission, RU as described in Appendix 14. (Note 16) The means for performing the precoding is configured to perform the precoding using the results of the channel prediction. RU as described in Appendix 15. (Note 17) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The RU specified in any one of the appendices 14-16. (Note 18) The channel estimation includes estimating the channel characteristics between the User Equipment (UE) and the RU using the reception result of at least one of the Sounding Reference Signal (SRS) and Uplink Demodulation Reference Signal (DMRS) transmitted from the UE. The channel prediction includes a temporal prediction of the channel characteristics, eigenvectors for downlink transmission to the UE, precoding weights for downlink transmission, beamforming weights for downlink transmission, or downlink beam for downlink transmission, using the results of the channel estimation. The RU specified in any one of the appendices 14-17. (Note 19) It further includes means for dynamically allocating uplink Sounding Reference Signal (SRS) resources. The RU specified in any one of the appendices 14-18. (Note 20) The communication means is configured to send information indicating dynamically determined uplink SRS resource allocation to the DU, which is configured to schedule either or both uplink and downlink resources, via the fronthaul interface. RU as described in Appendix 19. (Note 21) The communication means is configured to send the information indicating the uplink SRS resource allocation to the DU in response to receiving a request from the DU. RU as described in Appendix 20. (Note 22) The communication means is configured to autonomously send the information indicating the uplink SRS resource allocation to the DU in response to an update of the uplink SRS resource allocation. RU as described in Appendix 20. (Note 23) The communication means is configured to receive information indicating resource allocation to User Equipment (UE) from the DU via the fronthaul interface. The RU specified in any one of the appendices 19 to 22. (Note 24) The means for dynamically allocating the uplink SRS resources is configured to allocate the uplink SRS resources to the UE using the information indicating the resource allocation. RU as described in Appendix 23. (Note 25) Perform lower physical layer signal processing. Communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a fronthaul interface, and To perform channel estimation and channel prediction, A method performed by a Radio Unit (RU) equipped with [a specific component]. (Note 26) To manufacture at least one of the following: Radio Unit (RU), Distributed Unit (DU), and Controller, to perform both channel estimation and channel prediction. A method for providing this. (Note 27) The RU is configured to perform lower physical layer signal processing, The aforementioned DU is configured to perform upper-level physical layer signal processing, The controller is configured to perform near real-time control of wireless access network elements and resources, including at least the DU. The method described in Appendix 26. (Note 28) The manufacturing described above comprises manufacturing the RU such that the RU performs the channel estimation and the channel prediction. The method described in Appendix 26 or 27. (Note 29) The RU is further configured to perform precoding for downlink transmission. The method described in Appendix 28. (Note 30) The RU is configured to perform the precoding using the channel prediction results. The method described in Appendix 29. (Note 31) The RU further comprises manufacturing the RU to perform dynamic allocation of uplink Sounding Reference Signal (SRS) resources. The method described in any one of the appendices 28 to 30. (Note 32) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The controller is a Near-Real-Time RAN Intelligent Controller compliant with the O-RAN technical specifications. The method described in any one of the items in Appendix 26 to 31. (Note 33) The channel estimation includes estimating the channel characteristics between the User Equipment (UE) and the RU using the reception result of at least one of the Sounding Reference Signal (SRS) and Uplink Demodulation Reference Signal (DMRS) transmitted from the UE. The channel prediction includes a temporal prediction of the channel characteristics, eigenvectors for downlink transmission to the UE, precoding weights for downlink transmission, beamforming weights for downlink transmission, or downlink beam for downlink transmission, using the results of the channel estimation. The method described in any one of the appendices 26 to 32. (Note 34) A means for communicating with a Radio Unit (RU) configured to perform lower physical layer signal processing via a front-haul interface, A means for performing upper-level physical layer signal processing, Means for performing at least one of uplink scheduling and downlink scheduling, Means for receiving information indicating the dynamically determined uplink Sounding Reference Signal (SRS) resource allocation to User Equipment (UE) from the RU or Central Unit (CU) configured to perform dynamic uplink SRS resource allocation, A Distributed Unit (DU) equipped with [a specific feature / feature]. (Note 35) The system further includes means for requesting the RU or CU to transmit the information indicating the uplink SRS resource allocation. DU as described in Appendix 34. (Note 36) The receiving means is configured to receive the information indicating the uplink SRS resource allocation from the RU via a control plane message in the fronthaul interface. DU as described in Appendix 34 or 35. (Note 37) The means for performing at least one of the uplink scheduling and the downlink scheduling is configured to determine one or both of the uplink resources and downlink resources to be assigned to the UE using the information indicating the uplink SRS resource allocation. The DU specified in any one of the appendices 34-36. (Note 38) The system further includes means for sending information indicating resource allocation to the UE to the RU or CU configured to perform the dynamic uplink SRS resource allocation. The DU specified in any one of the appendices 34-37. (Note 39) The sending means is configured to send the information indicating the resource allocation to the RU via a control plane message in the fronthaul interface. DU as described in Appendix 38. (Note 40) The information indicating the resource allocation is used by the RU or CU to determine which uplink SRS resources are allocated to the UE. DU as described in Appendix 38 or 39. (Note 41) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The CU is an O-RAN Central Unit that conforms to the O-RAN technical specifications. The DU specified in any one of the appendices 34-40. (Note 42) To communicate with a Radio Unit (RU) configured to perform lower physical layer signal processing via a fronthaul interface, Performing upper-level physical layer signal processing, To perform at least one of uplink scheduling and downlink scheduling, Receiving information indicating the dynamically determined uplink Sounding Reference Signal (SRS) resource allocation to User Equipment (UE) from the RU or Central Unit (CU) configured to perform dynamic uplink SRS resource allocation, A method carried out by a Distributed Unit (DU) that includes the following. (Note 43) To communicate with a Radio Unit (RU) configured to perform lower physical layer signal processing via a fronthaul interface, Performing upper-level physical layer signal processing, To perform at least one of uplink scheduling and downlink scheduling, Receiving information indicating the dynamically determined uplink Sounding Reference Signal (SRS) resource allocation to User Equipment (UE) from the RU or Central Unit (CU) configured to perform dynamic uplink SRS resource allocation, A program for causing a computer to perform a method for a Distributed Unit (DU) equipped with [a specific feature / function]. (Note 44) Means for performing lower physical layer signal processing, A means for communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a front-haul interface, A means of dynamically allocating uplink Sounding Reference Signal (SRS) resources to User Equipment (UE), Means for sending information indicating the allocation of uplink SRS resources to the UE to the DU, which is configured to perform at least one of uplink scheduling and downlink scheduling, A Radio Unit (RU) equipped with [this feature]. (Note 45) The sending means is configured to send the information indicating the uplink SRS resource allocation to the DU in response to receiving a request from the DU. RU as described in Appendix 44. (Note 46) The sending means is configured to autonomously send the information indicating the uplink SRS resource allocation to the DU in response to an update of the uplink SRS resource allocation. RU as described in Appendix 44. (Note 47) The sending means is configured to send the information indicating the uplink SRS resource allocation to the DU via a control plane message in the fronthaul interface. The RU specified in any one of the appendices 44 to 46. (Note 48) The system further includes means for receiving information from the DU indicating resource allocation to the UE, The RU specified in any one of the appendices 44 to 47. (Note 49) The means for dynamically allocating resources is configured to determine the uplink SRS resources to be allocated to the UE using the information indicating the resource allocation. RU as described in Appendix 48. (Note 50) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The RU specified in any one of the appendices 44-49. (Note 51) Perform lower physical layer signal processing. Communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a fronthaul interface, Dynamically assigning uplink Sounding Reference Signal (SRS) resources to User Equipment (UE), and Information indicating the allocation of uplink SRS resources to the aforementioned UE is sent to the DU, which is configured to perform at least one of uplink scheduling and downlink scheduling. A method performed by a Radio Unit (RU) equipped with [a specific component]. (Note 52) A means for communicating with a Radio Unit (RU) configured to perform lower physical layer signal processing via a front-haul interface, A means for performing upper-level physical layer signal processing, Means for performing at least one of uplink scheduling and downlink scheduling, Means for sending information indicating resource allocation to User Equipment (UE) obtained by at least one of the uplink scheduling and downlink scheduling to the RU or Central Unit (CU) configured to perform dynamic uplink Sounding Reference Signal (SRS) resource allocation to the UE, A Distributed Unit (DU) equipped with [a specific feature / feature]. (Note 53) The sending means is configured to send the information indicating the resource allocation to the RU via a control plane message in the fronthaul interface. DU as described in Appendix 52. (Note 54) The information indicating the resource allocation is used by the RU or CU to determine which uplink SRS resources are allocated to the UE. DU as described in Appendix 52 or 53. (Note 55) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The CU is an O-RAN Central Unit that conforms to the O-RAN technical specifications. The DU specified in any one of the appendices 52 to 54. (Note 56) To communicate with a Radio Unit (RU) configured to perform lower physical layer signal processing via a fronthaul interface, Performing upper-level physical layer signal processing, To perform at least one of uplink scheduling and downlink scheduling, Sending information indicating resource allocation to User Equipment (UE) to the RU or Central Unit (CU) configured to perform dynamic uplink Sounding Reference Signal (SRS) resource allocation to the UE, A method carried out by a Distributed Unit (DU) that includes the following. (Note 57) To communicate with a Radio Unit (RU) configured to perform lower physical layer signal processing via a fronthaul interface, Performing upper-level physical layer signal processing, To perform at least one of uplink scheduling and downlink scheduling, Sending information indicating resource allocation to User Equipment (UE) to the RU or Central Unit (CU) configured to perform dynamic uplink Sounding Reference Signal (SRS) resource allocation to the UE, A program for causing a computer to perform a method for a Distributed Unit (DU) equipped with [a specific feature / function]. (Note 58) Means for performing lower physical layer signal processing, A means for communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a front-haul interface, A means of dynamically allocating uplink Sounding Reference Signal (SRS) resources to User Equipment (UE), Means for receiving information from the DU indicating resource allocation to the UE, A Radio Unit (RU) equipped with [this feature]. (Note 59) The receiving means is configured to receive the information indicating the resource allocation from the DU via control plane messages in the fronthaul interface. RU as described in Appendix 58. (Note 60) The means for dynamically allocating resources is configured to determine the uplink SRS resources to be allocated to the UE using the information indicating the resource allocation. RU as described in Appendix 58 or 59. (Note 61) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The RU specified in any one of the appendices 58-60. (Note 62) Perform lower physical layer signal processing. Communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a fronthaul interface, Dynamically assigning uplink Sounding Reference Signal (SRS) resources to User Equipment (UE), Receiving information from the DU indicating resource allocation to the UE, A method performed by a Radio Unit (RU) equipped with [a specific component]. (Note 63) A Radio Unit (RU) configured to perform lower physical layer signal processing, A Distributed Unit (DU) configured to perform upper-level physical layer signal processing, A controller configured to perform near real-time control of wireless access network elements and resources, including at least the aforementioned DU, Equipped with, At least one of the RU, DU, and controller is configured to perform both channel estimation and channel prediction. Base station system. (Note 64) The one configured to perform the channel estimation and channel prediction is the RU. The base station system described in Appendix 63. (Note 65) The RU is further configured to perform at least one of uplink beamforming and downlink beamforming. The base station system described in Appendix 64. (Note 66) Performing at least one of the uplink beamforming and the downlink beamforming includes calculating the corresponding beamforming weights. The base station system described in Appendix 65. (Note 67) The RU is configured to perform at least one of uplink beamforming and downlink beamforming using the results of either or a combination of Sounding Reference Signal (SRS)-based channel prediction and / or uplink Demodulation Reference Signal (DMRS)-based channel prediction. The base station system described in Appendix 65 or 66. (Note 68) The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The controller is a Near-Real-Time RAN Intelligent Controller compliant with the O-RAN technical specifications. A base station system as described in any one of the appendices 63 to 67. (Note 69) The channel estimation includes estimating the channel characteristics between the User Equipment (UE) and the RU using the reception result of at least one of the Sounding Reference Signal (SRS) and Uplink Demodulation Reference Signal (DMRS) transmitted from the UE. The channel prediction includes a temporal prediction of the channel characteristics, eigenvectors for downlink transmission to the UE, precoding weights for downlink transmission, beamforming weights for downlink transmission, or downlink beam for downlink transmission, using the results of the channel estimation. A base station system as described in any one of the appendices 63 to 68. (Note 70) The channel prediction comprises predicting at least one of the following: (a)Channel state information (CSI); (b)Channel quality indicator (CQI); (c) Rank indicator (RI); (d) Eigenvectors of the channel response matrix (e)Signal to interference and noise ratio (SINR); (f)Precoding matrix indicator (PMI); (g) Angle of arrival (AoA); and (h) Output angle (AoD), A base station system as described in any one of the appendices 63 to 69. (Note 71) The DU is configured to perform at least one of uplink scheduling, downlink scheduling, and dynamic uplink SRS resource allocation. A base station system as described in any one of the appendices 63 to 70. (Note 72) The DU is configured to (a) perform at least one of uplink scheduling and downlink scheduling, and (b) receive information from the RU or Central Unit (CU) indicating uplink SRS resource allocation dynamically determined by the RU or CU. A base station system as described in any one of the items 63 to 71 of the appendices. (Note 73) The DU is configured to perform uplink scheduling based on at least one of dynamic scheduling and configured scheduling. A base station system as described in any one of the appendices 63 to 72. (Note 74) The DU is configured to perform downlink scheduling based on at least one of dynamic scheduling and semi-persistent scheduling. A base station system as described in any one of the appendices 63 to 73. (Note 75) The aforementioned prediction is made using at least one of an AI / ML-based method and a non-AI / ML-based method. A base station system as described in any one of the appendices 63 to 74. (Note 76) The aforementioned AI / ML-based method uses an AI / ML model based on at least one of the following: RNN, LSTM, CNN, transformer model, ML-mixer, FCN, and autoregression model. The base station system described in Appendix 75. (Note 77) The non-AI / ML-based method includes at least one of the following: sample-and-hold method, Wiener filter method, Kalman filter method, Berg method, and Yule-Walker method. The base station system described in Appendix 75. (Note 78) The DU and the RU are configured to exchange information including at least one of the following: (a) Sounding Reference Signal (SRS) configuration parameters; (b) Channel estimation parameters; (c) Channel prediction parameters; (d) Dynamic SRS scheduling parameters; and (e) Data scheduling parameters, A base station system as described in any one of the appendices 63 to 77. (Note 79) The SRS setting parameter includes at least one of the following: (a) SRS time domain position; (b) SRS frequency domain location; (c) SRS bandwidth; (d) SRS period; (e) Cyclic shift; (f) Sending com; (g) Time offset; (h) Frequency offset; and (i) Number of SRS ports, The base station system described in Appendix 78. (Note 80) The channel estimation parameter includes at least one of the following: (a) Channel estimation method; (b) Channel estimation granularity in the frequency domain; (c) Window type; and (d) Window size, The base station system described in Appendix 78. (Note 81) The channel estimation method includes at least one of the following: (a) LS algorithm; (b) MMSE algorithm; (c) DFT-based algorithms; and (d) DCT-based algorithms, The base station system described in Appendix 80. (Note 82) The channel prediction parameter includes at least one of the following: (a) Channel prediction settings; and (b) Required channel prediction output, The base station system described in Appendix 78. (Note 83) The channel prediction setting includes at least one of the following: (a) An indicator showing at least one of an AI / ML-based prediction method and a non-AI / ML-based prediction method; (b) A prediction method from a predefined list of prediction methods; and (c) Setup parameters of the prediction model, The base station system described in Appendix 82. (Note 84) The requested channel prediction output includes at least one of the following: (a) CSI; (b) CQI; (c) Eigenvectors; (d)RI; (e) PMI; (f) AoA; (g) AoD; and (h) SINR, The base station system described in Appendix 82. (Note 85) The dynamic SRS scheduling parameter includes at least one of the following: (a) SRS time domain position; (b) SRS frequency domain location; (c) SRS bandwidth; (d) SRS period; (e) Cyclic shift; (f) Sending com; (g) Time offset; (h) Frequency offset; and (i) Number of SRS ports, The base station system described in Appendix 78. (Note 86) The aforementioned data scheduling parameter includes at least one of the following: (a) PUSCH transmission resource; (b) PDSCH transmission resources; (c) PUCCH transmission resources; and (d) PDCCH transmission resources, The base station system described in Appendix 78. (Note 87) The aforementioned information is exchanged by at least one of the following: (a) A new C-Plane Section Type X; and (b) New Section Extension, The base station system described in Appendix 78. (Note 88) Means for performing lower physical layer signal processing, A means for communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a front-haul interface, Means for performing channel estimation and channel prediction, A Radio Unit (RU) equipped with [this feature]. (Note 89) Means for performing lower physical layer signal processing, A means for communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a front-haul interface, A means for performing channel estimation and channel prediction based on a Sounding Reference Signal (SRS), A Radio Unit (RU) equipped with [this feature]. (Note 90) Perform lower physical layer signal processing. Communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a fronthaul interface, and To perform channel estimation and channel prediction, A method performed by a Radio Unit (RU) equipped with [a specific component]. (Note 91) Perform lower physical layer signal processing. Communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a fronthaul interface, and To perform channel estimation and channel prediction based on a Sounding Reference Signal (SRS), A method performed by a Radio Unit (RU) equipped with [a specific component]. (Note 92) A Radio Unit (RU) configured to perform lower physical layer signal processing, A Distributed Unit (DU) configured to perform upper-level physical layer signal processing, A first controller configured to perform near real-time control of wireless access network elements and resources, including at least the aforementioned DU, Here, at least one of the RU, DU, and the first controller is configured to perform both channel estimation and channel prediction. A second controller configured to determine, based on at least one predetermined condition, where among the RU, the DU, and at least one of the first controllers, the channel estimation and channel prediction should be performed, Equipped with Base station system. (Note 93) Both the DU and the RU are configured to have the capability to perform the channel estimation and channel prediction, but only one of the DU and the RU is enabled by the second controller to perform the channel estimation and channel prediction based on at least one predetermined condition. The base station system described in Appendix 92. (Note 94) The channel estimation includes at least one of Sounding Reference Signal (SRS)-based channel estimation and Uplink Demodulation Reference Signal (DMRS)-based channel estimation. The base station system described in Appendix 92 or 93. (Note 95) The channel prediction includes at least one of a Sounding Reference Signal (SRS)-based channel prediction and an Uplink Demodulation Reference Signal (DMRS)-based channel prediction. A base station system as described in any one of the appendices 92 to 94. (Note 96) The aforementioned predetermined conditions are based on at least one of OFH traffic, latency, and OFH capacity. A base station system as described in any one of the appendices 92 to 95. [Explanation of Symbols]

[0125] 1. SMO Framework 2 Non-RT RIC 3. Near-RT RIC 4 O-CU-CP 5 O-CU-UP 6 O-DU 7 O-RU 8 O-Cloud 201 Processor 202 memory 203 Mass Storage 301 Front Haul Interface 302 Low PHY processors 303 DFE circuit 304 RF FE Circuit

Claims

1. A Radio Unit (RU) configured to perform lower physical layer signal processing, A Distributed Unit (DU) configured to perform upper-level physical layer signal processing, A controller configured to perform near real-time control of wireless access network elements and resources, including at least the aforementioned DU, Equipped with, At least one of the RU, DU, and controller is configured to perform both channel estimation and channel prediction. Base station system.

2. The one configured to perform the channel estimation and channel prediction is the RU. The base station system according to claim 1.

3. The RU is further configured to perform precoding for downlink transmission. The base station system according to claim 2.

4. The RU is configured to perform the precoding using the channel prediction results. The base station system according to claim 3.

5. The aforementioned RU is an O-RAN Radio Unit compliant with the Open Radio Access Network (O-RAN) technical specifications. The DU is an O-RAN Distributed Unit that conforms to the O-RAN technical specifications. The controller is a Near-Real-Time RAN Intelligent Controller compliant with the O-RAN technical specifications. The base station system according to any one of claims 1 to 4.

6. The channel estimation includes estimating the channel characteristics between the User Equipment (UE) and the RU using the reception result of at least one of the Sounding Reference Signal (SRS) and Uplink Demodulation Reference Signal (DMRS) transmitted from the UE. The channel prediction includes a temporal prediction of the channel characteristics, eigenvectors for downlink transmission to the UE, precoding weights for downlink transmission, beamforming weights for downlink transmission, or downlink beam for downlink transmission, using the results of the channel estimation. The base station system according to any one of claims 1 to 5.

7. The DU is configured to schedule either or both uplink and downlink resources, and to perform dynamic uplink Sounding Reference Signal (SRS) resource allocation. The base station system according to any one of claims 1 to 6.

8. The DU is configured to schedule either or both uplink and downlink resources, and to receive information from the RU or Central Unit (CU) indicating the uplink Sounding Reference Signal (SRS) resource allocation dynamically determined by the RU or CU. The base station system according to any one of claims 1 to 6.

9. Means for performing lower physical layer signal processing, A means for communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a front-haul interface, Means for performing channel estimation and channel prediction, A Radio Unit (RU) equipped with [a specific feature].

10. Perform lower physical layer signal processing. Communicating with a Distributed Unit (DU) configured to perform higher-level physical layer signal processing via a fronthaul interface, and To perform channel estimation and channel prediction, A method performed by a Radio Unit (RU) equipped with [a specific component].

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