Multi-user multiple input and multiple output using a master unit

Abstract

A master unit is configured to: receive a resource block from a distributed unit; receive a channel estimate or suggested beamforming weight from the distributed unit; check: (1) the channel estimate to associate coefficients with corresponding antenna elements of a radio unit, or (2) the suggested beamforming weight to associate coefficients with corresponding antenna elements of a radio unit; select a subset of antenna elements corresponding to: (1) a subset of coefficients of the channel estimate with the highest value or (2) a subset of coefficients of the suggested beamforming weight with the highest value; determine derived beamforming weights based on: (1) a subset of coefficients of the channel estimate with the highest value or (2) a subset of coefficients of the suggested beamforming weight with the highest value; apply the derived beamforming weights to the resource block; and transmit the resource block to a remote unit having antenna elements corresponding to: (1) a subset of coefficients of the channel estimate with the highest value or (2) a subset of coefficients of the suggested beamforming weight with the highest value.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Indian Provisional Patent Application Serial No. 202441002806 entitled “Smart Reuseusing Master Unit”, filed on January 15, 2024, which is incorporated herein by reference in its entirety. Background Technology

[0003] The O-RAN Alliance publishes a set of specifications in an open manner for implementing radio access networks. ("O-RAN" is an abbreviation for "Open RAN".) In O-RAN, each base station is typically implemented in a de-aggregated manner, where each base station is divided into at least one central unit (CU), at least one distributed unit (DU), and one or more radio units (RU). Each CU typically implements Layer 3 and non-time-critical Layer 2 functions for its associated base station. Each DU is typically configured to implement at least some of the time-critical Layer 2 functions and Layer 1 (also known as physical layer) functions for its associated base station. Each RU is typically configured to implement a radio frequency (RF) interface and physical layer functions not implemented in the DU for its associated base station. Summary of the Invention

[0004] A master unit for use in an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO) includes a circuit system configured to: receive resource blocks from distributed units of the open radio access network implementing MU-MIMO; receive channel estimates or proposed beamforming weights from the distributed units; check one of the following: (1) the channel estimate, to associate a first coefficient of the channel estimate with a corresponding antenna element of a plurality of radio units, or (2) the proposed beamforming weights, to associate a second coefficient of the proposed beamforming weights with the corresponding antenna element of the plurality of radio units; and select a subset of antenna elements corresponding to: (1) having the most (1) A first subset of the coefficients of the channel estimate with the highest value or (2) A second subset of the coefficients of the proposed beamforming weight with the highest value; Determine the derived beamforming weight for application to the resource block based on: (1) The first subset of the coefficients of the channel estimate with the highest value or (2) The second subset of the coefficients of the proposed beamforming weight with the highest value; Apply the derived beamforming weight to the resource block; and Transmit the resource block to a subset of radio units having a subset of antenna elements corresponding to: (1) The first subset of the coefficients of the channel estimate with the highest value or (2) The second subset of the coefficients of the proposed beamforming weight with the highest value.

[0005] A method for use in an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), comprising: receiving resource blocks from distributed units at a master unit of the open radio access network; receiving channel estimates or proposed beamforming weights from the distributed units at the master unit; checking at the master unit one of: (1) the channel estimate, associating a first coefficient of the channel estimate with corresponding antenna elements of a plurality of radio units, or (2) the proposed beamforming weights, associating a second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; selecting at the master unit a subset of antenna elements corresponding to: (1) the channel estimate having the highest magnitude. A first subset of coefficients or (2) a second subset of coefficients of the proposed beamforming weight having the highest value; at the master unit, a derived beamforming weight for application to the resource block is determined based on: (1) the first subset of coefficients of the channel estimate having the highest value or (2) the second subset of coefficients of the proposed beamforming weight having the highest value; the derived beamforming weight is applied to the resource block; and the resource block is transmitted from the master unit to a subset of radio units having the subset of antenna elements corresponding to: (1) the first subset of coefficients of the channel estimate having the highest value or (2) the second subset of coefficients of the proposed beamforming weight having the highest value.

[0006] An open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO) is provided, the open radio access network comprising: a plurality of radio units, each of the plurality of radio units including a first circuit system for exchanging radio frequency signals with at least one user equipment; and a master unit communicatively coupled to the plurality of radio units, the master unit including a second circuit system configured to: receive resource blocks from the distributed units; receive channel estimates or proposed beamforming weights from the distributed units; check one of the following: (1) the channel estimate, to associate a first coefficient of the channel estimate with a corresponding antenna element of the plurality of radio units, or (2) the proposed beamforming weights, to associate a second coefficient of the proposed beamforming weights with the corresponding antenna element of the plurality of radio units; and select an antenna. A subset of antenna elements, the subset of antenna elements corresponding to: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weight having the highest value; determining the derived beamforming weight for application to the resource block based on: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value; applying the derived beamforming weight to the resource block; and a subset of radio units for transmitting the resource block to the plurality of radio units, the subset of radio units having the subset of antenna elements corresponding to: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value. Attached Figure Description

[0007] It should be understood that the accompanying drawings only describe exemplary configurations and therefore should not be considered as a limitation of scope. The exemplary configurations will be described with additional features and details using the accompanying drawings, wherein:

[0008] Figure 1A-1B This is a block diagram illustrating an exemplary embodiment of a communication system in which the technologies described below may be used.

[0009] Figure 2 It shows including Figure 1A-1B A block diagram of an example communication system, which is part of a broader communication system, is shown.

[0010] Figure 3-3B This is a flowchart illustrating an exemplary method for use in an open radio access network that implements multi-user multiple-input multiple-output (MU-MIMO).

[0011] In accordance with common practice, the various features described are not drawn to scale, but rather drawn to emphasize specific features relevant to the exemplary configuration. Detailed Implementation

[0012] In O-RAN, each base station is typically implemented in a de-aggregated manner, where each base station is divided into at least one central unit (CU), at least one distributed unit (DU), and one or more radio units (RU). As used herein, the term "north" or "northward" means "upstream" or toward the core network, while the terms "south" or "southward" mean "downstream" or toward one or more RUs.

[0013] The O-RAN specification defines a “shared cell” configuration or implementation where multiple RUs serve a single cell. The O-RAN shared cell implementation attempts to utilize the bandwidth of the round-trip DU more efficiently (compared to O-RAN 1.0) to support fronthaul data communication with multiple RUs. The O-RAN shared cell implementation is described in detail in Section 13, “Support of Shared Cell,” of version 10.0 of the “O-RAN Working Group 4 (Open Fronthaul Interfaces WG) Control, User and Synchronization Plane Specification” (O-RAN.WG4.CUS.0-v10.00, hereinafter referred to as “O-RAN Specification Shared Cell Support”, available in PDF 252-270 at https: / / orandownloadsweb.azurewebsites.net / download?id=364).

[0014] In O-RAN shared cell implementations, two operating modes are typically present in the fronthaul: Fronthaul Multiplexer (FHM) mode and cascade mode. An example of implementing a shared cell includes FHM to more efficiently support one-DU to multiple RU mappings. In this example, the FHM: ​​(1) replicates the downlink packet stream (from the DU) for each RU; and (2) performs a combination / digital summation on the uplink packet streams from the RUs (before transmission to the DU). The combination / digital summation includes: (1) summing corresponding in-phase (I) samples in the corresponding physical resource blocks (PRBs) (from all RUs); (2) summing corresponding quadrature-phase (Q) samples in the corresponding PRBs (from all RUs); and (3) transmitting the combined I / Q data stream from the FHM to the DU. The combination / digital summation may optionally include some overflow management. Using a shared cell implementation, the DU can transmit and receive a single packet stream (with a bandwidth of approximately N PRBs) instead of M packet streams (one per RU, for a total bandwidth of approximately N PRBs x M RUs).

[0015] An FHM may be limited by the number of RUs that can connect to it (e.g., no more than 8 RUs in the example). In the example, multiple FHMs are cascaded and / or branched to support a larger number of RUs. In the example, each FHM only implements fronthaul transmission functions and does not include radio functions for transmitting and receiving RF signals with the UE. In the example, multicast is used in the downlink to reduce fronthaul bandwidth, and unicast is used in the uplink.

[0016] O-RAN currently does not consider reuse scenarios and has not defined its DU-RU interface for efficient implementation of reuse. As used in this paper, reuse refers to using the same frequency resources for multiple UE sets, each under a geographically diverse RU set. In the example, an existing O-RAN-defined interface can be used to perform a single Physical Cell Identifier (PCI) and reuse to maintain O-RAN compliance. In the example, intelligence is added to a Virtual Master Unit (vMU) or other Master Units (MUs) to interoperate with a DU having Multi-User Multiple-Input Multiple-Output (MU-MIMO) capability, while keeping the MU-MIMO-capable DU unaware of the distributed nature of the RU. In the example, the MU-MIMO-capable DU is a MU-MIMO DU based on Sounding Reference Signals (SRS). In the example, the MU-MIMO-capable DU is a MU-MIMO DU based on Channel Start Information Reference Signals (CSI-RS). In the example, the O-RAN interface is used between the DU and the vMU. In the example, the DU and vMU support beamforming methods defined by O-RAN.

[0017] In conventional MU-MIMO, the MU-MIMO DU has a co-located antenna array at the O-RU. In conventional MU-MIMO, the MU-MIMO DU assumes the existence of a co-located antenna array at the O-RU, which is calibrated to support coherent beamforming for MU-MIMO. In conventional MU-MIMO, the base station (BS) determines the resources to allocate to the UEs in the MU-MIMO and the number of layers for each UE. In conventional MU-MIMO, the base station defines a precoder matrix (or beam weight set) for the antenna array. In conventional MU-MIMO, the base station performs channel estimation and precoder determination based on (1) periodic SRS from the UE; and / or (2) UE CSI reports. In conventional MU-MIMO, the base station can utilize various beamforming algorithms, such as Maximum Ratio Transmission (MRT), Zero Forcing (ZF), Regularized Zero Forcing (RZF), etc.

[0018] In conventional MU-MIMO, group selection to select UEs is performed by the DU. In the example, the group selection for UE selection performed by the DU is complex and based on the cross-correlation of stacked channel estimates Ge and matrices, where Ge is a stacked set of channel matrices. In the example, each UE has a channel matrix between its antenna and the base station's antennas. In the case of distributed RUs, there will be at least one set of antenna rows or columns for each RU (such as two antennas, four antennas, or more). Therefore, each UE has such a channel matrix, and the DU operation is based on the stacked set of channel matrices. In the example, when the DU determines a subset of UEs to be reused, it stacks the channel matrices of the entire set into a composite matrix Ge, and based on cross-correlation... A subset for reuse is selected based on the cross-correlation, which gives the cross-correlation between the channel matrices of each pair of individual UEs in the group. For each pair of UEs in the subset, DU selects the subset with the lowest cross-correlation between each pair of UEs in the group for reuse. (Stack-based) Calculate the RZF beamforming weights.

[0019] In the example, O-RAN defines four beamforming methods for beam management, including: (1) predefined beamforming; (2) channel information-based beamforming; (3) weighted beamforming; and (4) attribute-based beamforming. In the example, any of the predefined beamforming, channel information-based beamforming, and weighted beamforming can be used with a distributed RU. In the example, different synchronization signal blocks (SSBs) or channel start information reference signals (CSI-RS) are associated with or transmitted through different beams.

[0020] In the example using predefined beamforming, the beams are predefined in the O-RU and can be applied in the frequency domain (for MU-MIMO) or time domain (analog beam steering), and the DU associates different synchronization signal blocks (SSBs) or channel start information reference signals (CSI-RS) with each beam. In the example using predefined beamforming, the beam management system is unaware of the beam details, and the beam system can only determine which beams it wants to use for a specific RU by using different beams with different CSI-RS, and then learn which beams are preferred from feedback from the UE.

[0021] In the example of beamforming using channel information, the channel information is transmitted to the RU via O-RAN segment type 6. In this example, the master unit forwards the SRS-specific PRB from the RU to the DU, and the DU estimates the channels based on the SRS and uses this as the basis for selecting UEs to be reused with multi-user MIMO and calculating the appropriate beam to use (depending on the specific UE to be reused). In this example, the DU assumes that either the MU or the RU calculates the beamforming. In this example, the DU expects coherent phase information in these channels and specific phase information incorporated into the beamforming weights to eliminate interference that would otherwise be present with this reuse. In this example, the DU periodically transmits the channels (identified by Ueld) for each UE via the C-plane to the O-RU, which stores and keeps the channels updated. In this example, the DU also instructs the Ueld(s) corresponding to the data (C-plane). In the example of using channel-information-based beamforming, the O-RU determines the appropriate precoder / beamforming weights based on the channels of the UE(s).

[0022] In the example using weighted beamforming, the O-DU configures the beamforming weights for each beam ID. In the example using attribute-based dynamic beamforming, azimuth, zenith, etc., need to be specified for each beam.

[0023] In conventional methods for MU-MIMO based on uplink (UL) channel estimation / reciprocity, the base station (BS) estimates the uplink (UL) channel matrix (He) for each base station (BS) antenna element for each UE based on receiving its assigned SRS under a specific periodicity (Tsrs) of the sounding reference signal (SRS). In conventional methods, the base station (BS) selects a set of UEs for reuse by choosing those with low cross-correlation within its uplink (UL) channel matrix (He). In this example, low cross-correlation indicates good candidate UEs for reuse. In this example, the base station (BS) uses beamforming algorithms (such as Maximum Ratio Transmission (MRT), Zero Forcing (ZF), Regularized Zero Forcing (RZF), etc.) to calculate beamforming weights based on the uplink (UL) channel matrix (He) to eliminate or reduce reuse interference associated with correlation. In this example, this method can be used for base stations with distributed RUs or co-located arrays.

[0024] The conventional coherent selection of beamforming is complex, and its interference suppression performance is sensitive to uplink (UL) / downlink (DL) channel mismatch due to either: (1) varying clock errors on the base station (BS) antenna elements that cause a mismatch between the uplink and downlink channels (which is particularly challenging for distributed RUs); or (2) channel aging during Tsrs due to UE mobility, rendering the SRS obsolete when beamforming with it. In the example, when the DU calculates the beam set based on its uplink channel matrix estimate, these beams do not particularly match the actual channels in the downlink in the presence of these errors. This is especially challenging for distributed RUs.

[0025] In the incoherent example, once the master unit (MU) receives the channel estimate or actual beamforming weights from the DU, the MU can identify the UE's (multiple) primary radio points (RPs). In this example, the beamforming weights are 1 in the primary RPs and 0 in the other RPs. In this example, given the beamforming weights, based on... A set of UEs was selected for MU-MIMO to achieve a low signal-to-interference ratio (SIR). In the example, the incoherent system has a smaller capacity density potential compared to the coherent system, but it exhibits a much lower sensitivity to clock errors and UE mobility.

[0026] Figure 1A-1B This is a block diagram illustrating an example of a communication system 100. Figure 1A A general example using the main unit (MU) 106 is shown, while Figure 1B A specific example using a virtual master unit (vMU) 106 is shown. Figure 1A-1BIn the example shown, the communication system 100 is implemented using O-RAN or other point-to-multipoint distributed base station architecture. The communication system 100 may also be referred to herein as “O-RAN” or “O-RAN system”. In the example, the communication system 100 includes at least one central unit (CU or O-CU) 102, at least one distributed unit (DU or O-DU) 104, at least one main unit (MU or vMU) 106, and at least one radio unit (RU or O-RU) 108 (such as radio unit (RU or O-RU) 108-1 and any number of optional radio units (RU or O-RU) 108-2 to optional radio units (RU or O-RU) 108-A), said at least one radio unit being configured to serve at least one user equipment (UE) 112 within a site providing wireless services.

[0027] In the example, at least one CU 102, at least one DU 104, and at least one RU 108 implement a “base station,” “base station entity,” or “base station system” (which may also be referred to as “evolved node B,” “eNodeB,” or “eNB” in the context of fourth-generation (4G) Long Term Evolution (LTE) systems; and as “gNodeB” or “gNB” in the context of fifth-generation (5G) New Radio (NR) systems; and may use different names in other current or future generations of radio access networks (RANs) and communication networks). In the example, at least one CU 102 and / or at least one DU 104 are located at a location remote from the site providing radio services, for example, in a centralized group of nodes. Additionally, the RUs 108 may be physically separated from each other at the site providing radio services, but they are each communicatively coupled to at least one DU 104 via at least one fronthaul network 120. The base station can be used to provide UE 112 with mobile access to the core network 114 of the wireless network operator, so that UE 112 can wirelessly transmit data and voice (using technologies such as LTE Voice (VoLTE) or 3GPP 5G RAN, Internet of Things (IoT), Ultra Reliable Low Latency Communication (URLLC) to provide wireless services using the 5G air interface).

[0028] In the example, the communication system 100 implements the base station as a corresponding 5G NR gNB (for ease of explanation, in...). Figure 1A-1B(Only one of them is shown in the example). In such a configuration, each CU 102 implements Layer 3 and non-time-critical Layer 2 functions for the 5G NR gNB. In the example, each CU 102 can be further divided into at least one control plane entity (“CU-CP”) and at least one user plane entity (“CU-UP”) that respectively handles control plane and user plane processing for the CU 102. In the example, each DU 104 is configured to implement time-critical Layer 2 functions for the gNB, and also implements at least some of the Layer 1 functions in addition to those described below. In this example, Figure 1A The main unit (MU) 106 and more specifically Figure 1B The virtual master unit (vMU) 106 is connected between DU 104 and each RU 108. In this example, the MU / vMU 106 manipulates the uplink signals sent to DU 104 and transforms the signals from DU 104 to support reuse with the distributed RU 108, even though DU 104 is unaware of the distributed RU 108, and remains configured as if an antenna array exists at the O-RU (not the distributed RU 108). In this example, each RU 108 is configured to implement physical layer functions, as well as RF interfaces, that are not implemented for the gNB in ​​DU 104 or MU / vMU 106. Furthermore, each RU 108 includes or is coupled to a corresponding set of one or more antennas 110 (such as antennas 110-1, 110-2, 110-3, and any number of antennas 110-4 to 110-A) for radiating downlink RF signals to the UE 112 and receiving uplink RF signals transmitted by the UE 112. In the example, for each RU 108, precoding is performed on each antenna 110 within the corresponding set of one or more antennas 110. In the example, the precoder weights (derived beamforming weights) for a given UE and the corresponding RU 108 are derived from the channel estimation or suggested beamforming weights provided by the distributed unit (DU) 104, or arbitrarily selected.

[0029] Generally, the communication system 100 is configured to provide wireless services to various user equipment (UE) 112, such as UE 112-1 and any number of optional UEs 112-2 to optional UEs 112-B. Unless explicitly stated otherwise, references to Layer 1, Layer 2, Layer 3, and other or equivalent layers (such as the physical layer or Media Access Control (MAC) layer) refer to the layer of the specific wireless interface (e.g., fourth-generation (4G) Long Term Evolution (LTE) or fifth-generation (5G) New Radio (NR)) used for wireless communication with the UE 112. Furthermore, it should be understood that 5G NR embodiments can be used in both standalone and non-standalone modes (or other modes developed in the future), and the following description is not intended to be limited to any particular mode. Additionally, while some embodiments are described herein as being implemented for use with 5G NR, other embodiments can be implemented for use with other wireless interfaces, and the following description is not intended to be limited to any particular wireless interface.

[0030] In the example, at least one CU 102 is communicatively coupled to at least one corresponding core network 114 of an associated wireless operator via at least one backhaul network 116. The at least one backhaul network 116 is typically a public wide area network such as the Internet, but it should be understood that the at least one backhaul network 116 can be implemented in other ways. In the example, at least one DU 104 is communicatively coupled to at least one CU 102 via at least one midhaul network 118. In the example, a midhaul interface published by the O-RAN Alliance is used between DU 104 and at least one CU 102 via at least one midhaul network 118. In the example, at least one RU 108 is communicatively coupled to at least one DU 104 via at least one fronthaul network 120. In the example, a fronthaul interface published by the O-RAN Alliance is used between each RU 108 and its corresponding DU 104 via at least one fronthaul network 120. In the example, each of the at least one backhaul network 116, at least one midhaul network 118, and / or at least one fronthaul network 120 can be implemented using one or more switches, routers, and / or other networking devices. In some examples, at least one backhaul network 116, at least one midhaul network 118, and / or at least one fronthaul network 120 can be implemented using switched Ethernet with switched Ethernet networks and Ethernet switches.

[0031] Although described in the context of 5G embodiments Figure 1A-1B(and the description set forth more generally herein), wherein each logical base station entity is divided into CU 102, DU 104, and RU 108, and for at least some of the physical channels, some physical layer processing is performed in DU 104, while the remaining physical layer processing is performed in RU 108. It should be understood that the techniques described herein can be used with other radio interfaces (e.g., 4G LTE) and with other ways of implementing base station entities (e.g., using a conventional baseband unit (BBU) / remote radio head (RRH) architecture). Therefore, references to CU, DU, MU, or RU in this specification and associated figures can also be considered to refer more generally to any entity (including, for example, any “base station” or “RAN” entity) implementing any function or feature described herein as being implemented by CU, DU, MU, or RU.

[0032] Each CU 102, DU 104, MU 106, and RU108, as well as any specific features described herein as implemented therein, may be implemented in hardware, software, or a combination of hardware and software, and the various implementations (whether hardware, software, or a combination of hardware and software) may also be generally referred to as a “circuit system,” “circuit,” or “multiple circuits” configured to implement at least some of the associated functions. When implemented in software, such software may be implemented in software or firmware that executes on one or more suitable programmable processors (or other programmable devices) or configures programmable devices (e.g., included in dedicated hardware, general-purpose hardware, and / or virtual platforms, or processors or devices for implementing dedicated hardware, general-purpose hardware, and / or virtual platforms). In such software examples, the software may include program instructions stored (or otherwise embodied) on or in suitable one or more non-transitory storage media (such as flash memory or other non-volatile memory, disk drives, and / or optical disc drives), from which a programmable processor or device reads at least a portion of the program instructions for its execution (and / or for otherwise configuring such a processor or device) to perform one or more functions described herein as implemented by software. Such hardware or software (or portions thereof) may be implemented in other ways (e.g., in field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), etc.).

[0033] Furthermore, each CU 102, DU 104, MU 106, and RU 108 can be implemented as a Physical Network Function (PNF) (e.g., using dedicated physical programmable devices and other circuitry) and / or a Virtual Network Function (VNF) (e.g., using one or more general-purpose servers (possibly with hardware acceleration) in a scalable cloud environment and at different locations within the carrier network (e.g., in the carrier's "edge cloud" or "central cloud"). Each VNF can be implemented using hardware virtualization, operating system virtualization (also known as containerization), and application virtualization, as well as various combinations of two or more of the foregoing. In the case of containerization used to implement a VNF, it can also be referred to as a "Containerized Network Function" (CNF). For example, in Figure 1A-1B In the exemplary embodiments shown, each RU 108 is implemented as a PNF and deployed in or near a physical location that will provide radio coverage, and each CU 102, DU 104, and MU 106 is implemented using a corresponding set of one or more VNFs deployed in a distributed manner within one or more clouds (e.g., within an “edge” cloud or a “central” cloud). Each CU 102, DU 104, MU 106, and RU 108, as well as any particular features described herein as implemented therein, may be implemented in other ways.

[0034] The links shown in communication system 100 can be implemented using one or more switches, routers, and / or other networking devices. Physical links between devices in at least one backhaul network 116, at least one midhaul network 118, and / or at least one fronthaul network 120 can be implemented using different media, such as conductive media (copper, multi-rate multimode cable, etc.) and optical media (optical fiber). In the example, each RU 108 and each physical node implementing each DU 104 thereon includes one or more Ethernet network interfaces to couple each RU 108 and each physical node implementing DU 104 and / or MU 106 to at least one fronthaul network 120 to facilitate communication between DU 104 and / or MU 106 and RU 108.

[0035] The RU 108 can be deployed at sites to provide wireless coverage and capacity for one or more wireless network operators. Sites providing wireless service can cover, for example, buildings or campuses, or (e.g., other groups of buildings used by one or more businesses, governments, or other business entities) other public places such as hotels, resorts, amusement parks, hospitals, shopping malls, university campuses, stadiums, or outdoor areas such as ski resorts, stadiums, or densely populated city centers. In some configurations, sites providing wireless service are at least partially (and optionally entirely) indoors, but other alternatives are possible.

[0036] Each UE 112 may be a computing device having at least one processor that executes instructions stored in memory, such as a mobile phone, tablet computer, mobile media device, mobile gaming device, laptop computer, vehicle-based computer, desktop computer, etc.

[0037] Each CU 102, DU 104, MU 106, and RU 108 can be implemented to use an air interface supporting one or more of Frequency Division Duplex (FDD) and / or Time Division Duplex (TDD). Furthermore, CU 102, (multiple) DU 104, (multiple) MU 106, and RU 108 can be implemented to use an air interface supporting one or more of Multiple Input Multiple Output (MIMO), Single Input Single Output (SISO), Single Input Multiple Output (SIMO), and / or beamforming schemes. For example, CU 102, (multiple) DU 104, (multiple) MU 106, and RU 108 can implement one or more of the 5G NR transmission modes. Additionally, the communication system 100 can be configured to support multiple air interfaces and / or multiple wireless operators.

[0038] In the downlink example, DU 104 transmits downlink control plane messages, downlink user plane messages, and uplink control plane messages to MU 106, which then copies and forwards these messages to RU 108. RU 108 uses the downlink control plane messages and downlink user plane messages to wirelessly transmit / receive / switch radio frequency signals using the corresponding antenna set 110 for reception by UE 112.

[0039] In the uplink example, MU 106 combines user data received from RU 108. RU 108 uses an antenna to wirelessly receive data over the air medium. In this example, the combination is an uplink summation. In this example, the combination is an uplink coherent combination that requires phase information for the data.

[0040] In the uplink example, for each uplink time slot, the serving DU schedules one or more UEs to transmit during that time slot. In the example, the DU sends an uplink control plane message to each RU, identifying a resource block (RB) for which the RU should provide baseband IQ data. The RB for which the RU should provide baseband IQ data is also referred to herein as a "fronthaul RB".

[0041] In embodiments where the baseband IQ data transmitted via the fronthaul includes frequency-domain baseband IQ data, the fronthaul RBs only include those RBs already allocated to the scheduled UE 112 for uplink transmission during that time slot. In embodiments where the baseband IQ data transmitted via the fronthaul includes time-domain baseband IQ data, the fronthaul RBs include all RBs for that time slot (due to the time-domain nature of the baseband IQ data). During each uplink time slot, for each antenna port, each RU 108 generates corresponding baseband IQ data for each fronthaul RB from the uplink RF analog signal received via the corresponding antenna associated with that RU 108. For each RU 108, for each uplink time slot, RU 108 generates an uplink user plane message (which includes the baseband IQ data generated at that RU 108 for the various fronthaul RBs and antenna ports) and transmits the uplink user plane message northward.

[0042] Each CU 102, DU 104, MU 106, and RU 108, as well as any specific feature described herein as implemented thereby, can be implemented in other ways. Additionally, it should be noted that the systems and methods described herein can also be used in other distributed RANs, such as distributed antenna systems (DAS).

[0043] Figure 2 This is a block diagram illustrating an example of a communication system 200. Figure 2 In the example shown, communication system 200 is implemented using O-RAN or other point-to-multipoint distributed base station architecture. In the example, communication system 200 includes a distributed unit (DU or O-DU) 202 (which may be as described herein). Figure 1A or Figure 1B Implementation of DU 104), at least one main unit (MU) 204 (which may be as described herein) Figure 1A MU 106 or Figure 1B The implementation of the virtual MU (vMU) 106 and multiple radio units (RU or O-RU) 206 (such as radio unit (RU or O-RU) 206-1, radio unit (RU or O-RU) 206-2, and any number of optional radio units (RU or O-RU) 206-3 to optional radio units (RU or O-RU) 206-C, which may be as described herein) Figure 1A or Figure 1B In the implementation of RU 108, the plurality of radio units are configured as at least one user equipment (UE) 208 (such as user equipment (UE) 208-1 to user equipment (UE) 208-D, which may be as described herein). Figure 1A or Figure 1B(Implementation of UE 112 in the example). In this example, at least one master unit (MU) 204 is communicatively coupled to DU 202 via fronthaul network 210.

[0044] In the example, RU 206-1 is communicatively coupled to master unit (MU) 204 via communication link 212-1, such that RU 206-1 is communicatively coupled to DU 202 via master unit (MU) 204. In the example, RU 206-2 is communicatively coupled to master unit (MU) 204 via communication link 212-2, such that RU 206-2 is communicatively coupled to DU 202 via master unit (MU) 204. In the example, any additional RU 206 is communicatively coupled to master unit (MU) 204 via communication link 212, such that RU 206 is communicatively coupled to DU 202 via master unit (MU) 204.

[0045] In the example, DU 202 is performing MU-MIMO based on the Sounding Reference Signal (SRS). In the example, DU 202 is performing MU-MIMO based on the Channel Start Information Reference Signal (CSI-RS). In the example, DU 202 determines the multi-user UE 208 to be reused and the number of layers for each UE 208. In the example, DU 202 selects the UE 208 to be reused based on the channel estimate derived from the SRS and then provides the UE 208 selection to MU 204. In the example, the number of layers is capped at the maximum number of layers for a given RU 206. In the example, DU 202 transmits channel information to MU 204 using O-RAN Function Partition Option 2. In other examples, DU 202 transmits channel information to MU 204 using other function partitioning options (such as Option 1, Option 3, Option 4, Option 5, Option 6, Option 7, Option 8, or any other function partitioning option number) or otherwise. In the example, MU 204 defines the incoherent cocast RU 206 based on channel information received from DU 202. In the example, a quantized signature vector (QSV) is used to define the incoherent cocast RU 206. In the example, MU 204 is aware of the decision regarding the selection of UE 208, which is already scheduled in reuse, and its resource blocks, and MU 204 provides a channel estimate. In the example, MU 204 uses the channel estimate for UE 208 to keep DU 202 updated, or to deliver proposed beamforming weights. In the example, DU 202 remains unaware of the incoherent transmissions from RU 206 and anticipates its interface with a single O-RU with an antenna array. In the example, no changes are required to the O-RAN compliant RU 206. In the example, RU 206 operates in O-RAN 7.2-A mode. In the example, communication between DU 202 and MU 204 conforms to O-RAN 7.2-B mode. In the example, communication between MU 204 and RU 206 conforms to O-RAN 7.2-A mode. In the example, the interface between DU 202 and MU 204 conforms to O-RAN Option 7.3 or O-RAN Uplink Performance Improvement (ULPI).

[0046] In the example, RU 206 is updated using either channel estimate. In the example, dynamically proposed beamforming weights are sent to the master unit. In the example, the combination of MU 204 and RU 206 presents DU 202 as a Class B RU (where a Class B RU is an RU that determines the precoder matrix (or beamweight set) of the antenna array). This results in DU 202 being configured as if it were communicating with an O-RU having an antenna array, when it is actually transmitting data with MU 204 as part of a distributed antenna system with RU 206 (where MU 204 transmits data between itself and RU 206 via fronthaul). In the example, RU 206 is a Class A RU (where a Class A RU is an RU that does not determine the precoder matrix (or beamweight set) of the antenna array).

[0047] In the example, MU 204 receives a transport block or resource block, along with a channel estimate or proposed beamforming weights, from DU 202. In the example, DU 202 calculates the proposed beamforming weights based on the channel estimate and then passes them to MU 204. In the example, DU passes the calculated channel estimate to MU 204, and MU derives the coefficients for the proposed beamforming weights. In the example, MU 204 generates a resource block and transmits it to (multiple) RUs 206 (which are O-RAN 7.2 compliant RUs). In the example, MU 204 checks (1) the channel estimate for the reused UE 208 within a given transmission time interval (TTI); or (2) the beamforming weights. In the example, DU 202 sends the beam ID to MU 204. In the example, MU 204 then identifies each coefficient (of the channel estimation or beamforming weights) corresponding to the antenna elements for which MU 204 knows this mapping relationship, and selects all the antenna elements used that have the highest coefficients in the channel estimation or proposed beamforming weights. The corresponding RU(s) 206 are the resource blocks to which the resource blocks are transmitted for each specific UE 208. In the example, each specific UE 208 has a corresponding set of RU(s) 206, and the channel estimate determined by MU 204 within the corresponding set of RU(s) 206 is the channel estimate closest to UE 208. In the example, those RU(s) with the channel estimates determined by MU 204 as closest to UE 208 are the RU(s) receiving the transport block. In the example, a similar method can be used to reuse uplink (UL) traffic applied to multiple UEs 208.

[0048] In the example, DU 202 is still configured to exchange data with an RU having an antenna array, and DU 202 expects (1) the RU's antenna array to be applying coherent weights to the data; or (2) the RU to calculate proposed beamforming weights based on channel estimation. In the example, DU 202 either passes the channel matrix (Ge) or the proposed beamforming weights, allowing MU 204 to access the channel matrix or beamforming weights of (multiple) UEs 208. In the example, MU 204 simply selects the highest magnitude entries in the channel matrix or beamforming weight matrix, and these entries correspond to a known RU 206 for that UE 208. In the example, a high magnitude means that UE 208 is close to a specific RU 206, and that the UE 208's transport box is only set to that RU 206 for transmission, and no other RU 206 is receiving or transmitting against that UE 208. In the example, the set of highest magnitude coefficients is selected and applied to a resource block. In the example, the resource block is transferred to the set of radio units that has the set of antenna elements corresponding to the set of highest magnitude coefficients.

[0049] In the example, the first UE 208 is selected by MU 204 (e.g., through polling, proportional fairness (PF) scheduling, or quality of service (QoS) scheduling) to ensure that each UE 208 receives a fair scheduling rate at least equal to that of SU-MIMO. In the example, subsequent UEs 208 are selected based on the uplink (UL) channel matrix to achieve low coherent cross-correlation or high incoherent signal-to-interference (SIR) ratio. In the example where DU 202 receives information about the selection of UE 208, DU 202 can select (multiple) UEs 208 for high incoherent SIR, and UE 208 receives additional scheduling opportunities based on its separation from other UEs 208. In the example, if a particular UE 208 is highly separated from other UEs 208, that particular UE 208 will receive additional scheduling opportunities, although each UE 208 receives a fair number of scheduling opportunities.

[0050] In the example, each RU 206 is unaware of what the other RUs 206 are doing. In the example, multicast is used from MU 204 to RU 206, ensuring that a given data set is received only by the RU 206 that will use it, and not sent to other RUs 206 to which the data is not assigned. In the example, selection occurs in the near real-time RAN Intelligent Controller (RIC) performing some MU-MIMO optimizations. In the example, the calculations for selection can occur in each TTI, as a new set of UEs 208 may exist in each TTI, and potentially a new set of proposed beamforming weights may exist. In the example, the proposed beamforming weights need to be checked to quickly determine which RUs 206 will receive which transport blocks and PRBs, allowing transmissions to be performed, and then they can start the next TTI again (which may be shortly thereafter, such as only 500 microseconds).

[0051] In the example, the cocast group can change every TTI, and even potentially within a TTI. In the example, a precoder resource block group includes a number of resource blocks that support the same UE 208 for reuse, and uses the same beamforming weights or cocast group on the PRBs within that group. In the example, it changes in the next group, allowing for reuse of a different set of UE 208 for the next group, and even potentially allowing the same UE 208 to be reused in two different groups. In the example, a different RU 206 is cocast in the next group compared to the first group. In the example, the cocast area of ​​UE 208 changes even across PRB groups during TTIs. In the example, different UEs are reused between one TTI and the next, and different sets of cocast groups are used between one TTI and the next.

[0052] In the example, when UE 208 connects to a 5G or LTE cell, resources (including Sounding Reference Signal (SRS) resources) are provided to UE 208. In the example, the resources allocated to UE 208 (such as time-domain or frequency-domain resources) have the opportunity to transmit uplink wideband SRS signals, from which the base station can derive channel estimates. In the example, SRS provides information to DU 202 in the uplink via RU 206 and MU 204. In the example, the resource blocks in which UE 208's SRS transmissions are received form the basis in DU 202, which processes these resource block groups to determine the channel estimate for UE 208. In the example, resource block groups and channel estimates for a specific TTI are used as the basis for selecting UE 208 for reuse. In the example, suggested beamforming weights are used as the basis for selecting UEs for reuse.

[0053] In the example, the selection of UE 208 is based on correlation. The example analyzes the cross-correlation between the individual UEs 208. In examples with low cross-correlation between UEs, these are good candidate UEs 208s for reuse together. In the example, DU 202 searches for UEs 208 with low correlation for reuse. In the example where two UEs 208 are located under different RUs 206, the power and channel matrices reside in two different RUs 206. In the example, low correlation is obtained when performing cross-correlation on them, even using incoherent beamforming methods.

[0054] In the example, DU 202 communicates with MU 204 as if it were a single RU, and MU 204 then performs mapping to reach the correct RU 206. In the example, DU 202 is unaware of any further splitting or transmission to the individual RU 206. In the example, apart from minimal differential RU 206 clock errors and minor channel aging, system 200 has a higher SIR than conventional methods using coherent beamforming. In the example, the distributed RU 206 is less sensitive to clock errors than conventional coherent selection and beamforming, which are highly sensitive to clock errors. In the example, the distributed RU 206 is also less sensitive to Doppler effects. In the example, when UE 208 transmits an SRS and then moves away from its initial SRS transmission location, the channel has changed, and therefore, the coherent calculation of the proposed beamforming weights no longer matches well with the downlink channel present later after the SRS. In the example, UE selection based on channel matrix correlation has a lower SIR than UE selection based on conventional coherent selection, but still performs well.

[0055] In the example, system 200 can support a conventional DU 202, which selects UE 208 for MU-MIMO and shares channel information with RU 206, with RU 206 expected to apply beamforming. In the example, system 200 applies unicast / co-cast transmissions to its corresponding primary RU 206 determined from channel estimation for UE 208. In the example, any transmission initiated from its associated RU 206 to any given UE 208 will cause low interference to any other UE 208 scheduled for the same time or frequency resources. In the example, system 200 is less complex and has more robust performance compared to conventional coherent selection and beamforming. In the example, if DU 202 performs UE selection based on coherent channel cross-correlation without limiting selection, the SIR benefits and robustness will be significantly lost.

[0056] Figure 3-3BThis is a flowchart illustrating an exemplary method 300-300B for use in an open radio access network that implements multiple-user multiple-input multiple-output (MU-MIMO). Figure 3 Example method 300 is shown, which broadly covers examples of using channel estimation or suggesting beamforming weights. Figure 3A Example method 300A is shown, which more narrowly covers examples using channel estimation. Figure 3B Example method 300B is shown, which more narrowly covers examples using the proposed beamforming weights. Example methods (such as example method 300, example method 300A, or example method 300B) can be implemented using any of the following: Figure 1A-1B The example communication system 100 shown and described above includes the main unit (MU) 106 or virtual main unit (MU) 106 and any other components, or Figure 2 The example communication system 200 shown and described above includes the main unit (MU) 204 and any other components.

[0057] Example method 300 begins at step 302, where resource blocks are received from distributed units at the master unit of the open radio access network. In this example, method 300 includes receiving a group of resource blocks at the master unit and selecting, based on the resource block group, which user equipment to reuse. Example method 300 proceeds to step 304, where channel estimates or suggested beamforming weights are received from distributed units at the master unit. Figure 3A In the example of method 300A using channel estimation, step 304A includes receiving channel estimation from the distributed unit at the master unit. According to... Figure 3A In the example of example method 300A using channel estimation, example method 300A also includes receiving the channel estimate by examining the coefficients of the channel matrix to associate each coefficient of the channel matrix with a corresponding antenna element of a plurality of radio units. Figure 3B In the example of Example Method 300B using the proposed beamforming weights, step 304B includes receiving the proposed beamforming weights from the distributed cells at the master cell.

[0058] Example method 300 proceeds to step 306, where one of the following is checked at the main unit: (1) channel estimation to associate a first coefficient of the channel estimation with the corresponding antenna element of the plurality of radio units, or (2) suggested beamforming weights to associate a second coefficient of the suggested beamforming weights with the corresponding antenna element of the plurality of radio units. Figure 3A In the example method 300A using channel estimation, step 306A includes checking the channel estimation at the main unit to associate the first coefficients of the channel estimation with the corresponding antenna elements of the plurality of radio units. Figure 3B In the example of Example Method 300B using the proposed beamforming weights, step 306B includes checking the proposed beamforming weights at the main unit to associate a second coefficient of the proposed beamforming weights with the corresponding antenna element of the plurality of radio units.

[0059] Example method 300 proceeds to step 308, where a subset of antenna elements is selected at the main unit, the subset corresponding to: (1) a first subset of the coefficients of the channel estimation with the highest magnitude or (2) a second subset of the coefficients of the proposed beamforming weights with the highest magnitude. Based on... Figure 3A In example method 300A, which uses channel estimation, step 308A includes selecting a subset of antenna elements at the main element that corresponds to a first subset of the coefficients of the channel estimation with the highest magnitude. When using according to... Figure 3B In the example of the suggested beamforming weights in Example Method 300B, step 308 includes selecting a subset of antenna elements at the main unit that corresponds to a second subset of the coefficients of the suggested beamforming weights with the highest magnitude.

[0060] Example method 300 proceeds to step 310, where at the main unit, the derived beamforming weights to be applied to the resource block are determined based on: (1) a first subset of the coefficients of the channel estimate with the highest magnitude or (2) a second subset of the coefficients of the proposed beamforming weights with the highest magnitude. When using according to Figure 3A In the example of channel estimation in example method 300A, step 310A includes determining the derived beamforming weights to be applied to the resource block at the master cell based on a first subset of the coefficients of the channel estimation with the highest magnitude. When using... Figure 3B In the example of the suggested beamforming weights in Example Method 300B, step 310B includes determining, at the master cell, the derived beamforming weights to be applied to the resource block based on a second subset of the coefficients of the suggested beamforming weights having the highest magnitude.

[0061] Example method 300 proceeds to step 312, where derived beamforming weights are applied to the resource block. Example method 300 proceeds to step 314, where the resource block is transferred from the master unit to a subset of radio units, the subset of radio units having a subset of antenna elements corresponding to: (1) a first subset of coefficients of the channel estimation with the highest magnitude or (2) a second subset of coefficients of the proposed beamforming weights with the highest magnitude. When using according to Figure 3A In an example of channel estimation in method 300A, step 314A includes transferring a resource block from the master unit to a subset of radio units containing a subset of antenna elements having coefficients corresponding to a first subset of channel estimates with the highest magnitude. When using... Figure 3BIn the example of the proposed beamforming weights in example method 300B, step 314B includes transferring a resource block from the master unit to a subset of radio units of antenna elements having coefficients corresponding to the proposed beamforming weights with the highest magnitudes. Examples using resource blocks or proposed beamforming weights (including...) Figure 3 Method 300 Figure 3A Method 300A or Figure 3B In any of the methods 300), multicasting of resource blocks to radio element subsets is only sent to radio element subsets having antenna element subsets corresponding to: (1) a first subset of coefficients of channel estimation with the highest magnitude or (2) a second subset of coefficients of proposed beamforming weights with the highest magnitude. Examples of using resource blocks or proposed beamforming weights (including...) Figure 3 Method 300 Figure 3A Method 300A or Figure 3B In any of the methods 300, the method further includes deriving precoder weights for user equipment in an open radio access network based on channel estimation or suggested beamforming weights received from the distributed unit.

[0062] In the example, any transmission initiated from its associated RU to any given UE will cause low interference to any other UE scheduled for the same time or frequency resources. In the example, transmitting resource blocks from the master unit to a set of radio units containing antenna elements having the highest set of magnitude coefficients corresponding to at least one of the channel estimation or beamforming weight sets results in low coherent cross-correlation. In the example, transmitting resource blocks from the master unit to the set of radio units is performed using multicast only to the set of radio units containing antenna elements having the highest set of magnitude coefficients corresponding to at least one of the channel estimation or beamforming weight sets. In the example, method 300 also includes receiving a group of resource blocks at a distributed unit; and selecting, at the distributed unit, which UE to reuse based on the group of resource blocks.

[0063] the term

[0064] The following provides brief definitions of the terms, abbreviations and phrases used throughout this application.

[0065] The term "determine" and its variations can include calculation, extraction, generation, operation, processing, derivation, modeling, research, searching (e.g., searching in a table, database, or another data structure), ascertainment, etc. Furthermore, "determine" can also include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), etc. Additionally, "determine" can include parsing, selecting, choosing, building, etc.

[0066] Unless otherwise explicitly stated, the phrase “based on” does not mean “based on only.” In other words, the phrase “based on” describes both “based on only” and “based on at least”. Additionally, the term “and / or” means “and” or “or.” For example, “A and / or B” can mean “A,” “B,” or “A and B.” Furthermore, “A, B, and / or C” can mean “A alone,” “B alone,” “C alone,” “A and B,” “A and C,” “B and C,” or “A, B, and C.”

[0067] The terms “connection,” “coupling,” and “communicatively coupled,” and related terms, may refer to a direct or indirect connection. If the specification indicates that “may,” “can,” “could,” or “might” includes a component or feature or has a characteristic, then it is not necessary to include that particular component or feature or to have that characteristic.

[0068] The term "response" or "in response to" can indicate that an action has been performed, either fully or partially, in response to another action. The term "module" refers to a functional component implemented in software, hardware, or firmware (or any combination thereof).

[0069] The methods disclosed herein include one or more steps or actions for implementing the described methods. Unless the specific order of the steps or actions is required for the proper functioning of the described methods, the order and / or use of particular steps and / or actions may be modified without departing from the scope of the claims.

[0070] While a detailed description of one or more configurations of this disclosure has been given above, various alternatives, modifications, and equivalents will be apparent to those skilled in the art without departing from the spirit of this disclosure. For example, although the above-described configurations refer to specific features, functions, processes, components, elements, and / or structures, the scope of this disclosure also includes configurations having different combinations of features, functions, processes, components, elements, and / or structures, as well as configurations that do not include all the described features, functions, processes, components, elements, and / or structures. Therefore, the scope of this disclosure is intended to cover all such alternatives, modifications, and variations, as well as all their equivalents, that fall within the scope of the claims. Therefore, the above description should not be considered limiting.

[0071] Example

[0072] Example 1 includes a master unit for use in an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), the master unit comprising: a circuit system configured to: receive resource blocks from distributed units of the open radio access network implementing MU-MIMO; receive channel estimates or proposed beamforming weights from the distributed units; check one of the following: (1) the channel estimate, to associate a first coefficient of the channel estimate with a corresponding antenna element of a plurality of radio units, or (2) the proposed beamforming weights, to associate a second coefficient of the proposed beamforming weights with the corresponding antenna element of the plurality of radio units; and select a subset of antenna elements corresponding to: (1) A first subset of the coefficients of the channel estimate having the highest value or (2) A second subset of the coefficients of the proposed beamforming weight having the highest value; Determine the derived beamforming weights to be applied to the resource block based on: (1) The first subset of the coefficients of the channel estimate having the highest value or (2) The second subset of the coefficients of the proposed beamforming weight having the highest value; Apply the derived beamforming weights to the resource block; and Transmit the resource block to a subset of radio units having the subset of antenna elements corresponding to: (1) The first subset of the coefficients of the channel estimate having the highest value or (2) The second subset of the coefficients of the proposed beamforming weight having the highest value.

[0073] Example 2 includes the main unit described in Example 1, and further includes the circuitry configured to: receive the channel estimate from the distributed unit; examine the channel estimate to associate the first coefficients of the channel estimate with the corresponding antenna elements of the plurality of radio units; select a subset of antenna elements corresponding to a first subset of the coefficients of the channel estimate having the highest value; determine the derived beamforming weights to be applied to the resource block based on the first subset of the coefficients of the channel estimate having the highest value; apply the derived beamforming weights to the resource block; and transmit the resource block to the subset of radio units having the subset of antenna elements corresponding to the first subset of the coefficients of the channel estimate having the highest value.

[0074] Example 3 includes the main unit described in Example 2, wherein the circuit system is configured to: receive the channel estimate as a channel matrix; and examine the channel estimate by checking the coefficients of the channel matrix to associate each coefficient of the channel matrix with the corresponding antenna element of the plurality of radio units.

[0075] Example 4 includes the main unit of any one of Examples 1-3, further comprising the circuitry configured to: receive the proposed beamforming weights from the distributed unit; examine the proposed beamforming weights to associate a second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; select the subset of antenna elements corresponding to a second subset of the coefficients of the proposed beamforming weights having the highest value; determine the derived beamforming weights to be applied to the resource block based on the second subset of the coefficients of the proposed beamforming weights having the highest value; apply the derived beamforming weights to the resource block; and transmit the resource block to the subset of radio units having the subset of antenna elements corresponding to the second subset of the coefficients of the proposed beamforming weights having the highest value.

[0076] Example 5 includes the main unit of any one of Examples 1-4, wherein the circuitry is configured to transmit the resource block to the radio unit subset only via multicast to the radio unit subset having the following: (1) the first subset of coefficients of the channel estimate having the highest value or (2) the second subset of coefficients of the proposed beamforming weight having the highest value.

[0077] Example 6 includes the main unit of any one of Examples 1-5, wherein the circuitry is configured to derive the precoder weights of the user equipment of the open radio access network based on the channel estimate or the proposed beamforming weights received from the distributed unit.

[0078] Example 7 includes a method for use in an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), the method comprising: receiving a resource block from a distributed unit at a master unit of the open radio access network; receiving a channel estimate or proposed beamforming weight from the distributed unit at the master unit; checking at the master unit one of: (1) the channel estimate, associating a first coefficient of the channel estimate with a corresponding antenna element of a plurality of radio units, or (2) the proposed beamforming weight, associating a second coefficient of the proposed beamforming weight with the corresponding antenna element of the plurality of radio units; selecting at the master unit a subset of antenna elements corresponding to: (1) the signal element with the highest magnitude value. (1) a first subset of the coefficients of the channel estimation with the highest value or (2) a second subset of the coefficients of the proposed beamforming weight with the highest value; at the master unit, a derived beamforming weight for application to the resource block is determined based on: (1) the first subset of the coefficients of the channel estimation with the highest value or (2) the second subset of the coefficients of the proposed beamforming weight with the highest value; the derived beamforming weight is applied to the resource block; and the resource block is transmitted from the master unit to a subset of radio units having a subset of antenna elements corresponding to: (1) the first subset of the coefficients of the channel estimation with the highest value or (2) the second subset of the coefficients of the proposed beamforming weight with the highest value.

[0079] Example 8 includes the method of Example 7, further comprising: receiving the channel estimate from the distributed unit at the master unit; examining the channel estimate at the master unit to associate the first coefficients of the channel estimate with the corresponding antenna elements of the plurality of radio units; selecting, at the master unit, a subset of antenna elements corresponding to a first subset of the coefficients of the channel estimate having the highest value; determining, at the master unit, the derived beamforming weights to be applied to the resource block based on the first subset of the coefficients of the channel estimate having the highest value; applying the derived beamforming weights to the resource block at the master unit; and transmitting the resource block from the master unit to the subset of radio units having the antenna element subset corresponding to the first subset of the coefficients of the channel estimate having the highest value.

[0080] Example 9 includes the method of Example 8, further comprising: receiving the channel estimate as a channel matrix at the master unit; and examining the channel estimate at the master unit by examining the coefficients of the channel matrix to associate each coefficient of the channel matrix with the corresponding antenna element of the plurality of radio units.

[0081] Example 10 includes the method of any one of Examples 8-9, further comprising: receiving a group of resource blocks at the distributed unit; and selecting, at the distributed unit, which user equipment to reuse based on the group of resource blocks.

[0082] Example 11 includes the method of any one of Examples 7-10, further comprising: receiving the proposed beamforming weights from the distributed units at the master unit; examining the proposed beamforming weights at the master unit to associate a second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; selecting, at the master unit, a subset of antenna elements corresponding to a second subset of the coefficients of the proposed beamforming weights having the highest value; determining, at the master unit, the derived beamforming weights to be applied to the resource block based on the second subset of the coefficients of the proposed beamforming weights having the highest value; applying the derived beamforming weights to the resource block at the master unit; and transmitting the resource block from the master unit to the subset of radio units having the antenna element subsets corresponding to the second subset of the coefficients of the proposed beamforming weights having the highest value.

[0083] Example 12 includes the method of any one of Examples 7-11, wherein the transmission of the resource block from the master unit to the radio unit subset is performed using multicast only to the radio unit subset having the following: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value.

[0084] Example 13 includes the method of any one of Examples 7-12, further comprising: deriving precoder weights for user equipment in the open radio access network based on the channel estimate or the proposed beamforming weights received from the distributed unit.

[0085] Example 14 includes an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), the open radio access network comprising: a plurality of radio units, each of the plurality of radio units including a first circuitry for exchanging radio frequency signals with at least one user equipment; and a master unit communicatively coupled to the plurality of radio units, the master unit including a second circuitry configured to: receive resource blocks from distributed units; receive channel estimates or proposed beamforming weights from the distributed units; and check one of the following: (1) the channel estimate, to associate a first coefficient of the channel estimate with a corresponding antenna element of the plurality of radio units, or (2) the proposed beamforming weights, to associate a second coefficient of the proposed beamforming weights with the corresponding antenna element of the plurality of radio units; Select a subset of antenna elements, the subset of antenna elements corresponding to: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weight having the highest value; determine the derived beamforming weight for application to the resource block based on: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value; apply the derived beamforming weight to the resource block; and transmit the resource block to a subset of radio units of the plurality of radio units, the subset of radio units having the subset of antenna elements corresponding to: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value.

[0086] Example 15 includes the open radio access network of Example 14, further comprising the second circuitry of the master unit configured to: receive the channel estimate from the distributed unit; examine the channel estimate to associate the first coefficients of the channel estimate with the corresponding antenna elements of the plurality of radio units; select a subset of antenna elements corresponding to a first subset of the coefficients of the channel estimate having the highest value; determine the derived beamforming weights to be applied to the resource block based on the first subset of the coefficients of the channel estimate having the highest value; and transmit the resource block to the subset of radio units having the antenna element subset corresponding to the first subset of the coefficients of the channel estimate having the highest value.

[0087] Example 16 includes the open radio access network of Example 15, wherein the second circuitry of the master unit is configured to: receive the channel estimate as a channel matrix; and examine the channel estimate by checking the coefficients of the channel matrix to associate each coefficient of the channel matrix with the corresponding antenna element of the plurality of radio units.

[0088] Example 17 includes an open radio access network as described in any one of Examples 14-16, further comprising the second circuitry of the master unit configured to: receive the proposed beamforming weights from the distributed unit; examine the proposed beamforming weights to associate a second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; determine the derived beamforming weights to be applied to the resource block based on a second subset of the coefficients of the proposed beamforming weights having the highest value; apply the derived beamforming weights to the resource block; and transmit the resource block to the subset of radio units having the subset of antenna elements corresponding to the second subset of the coefficients of the proposed beamforming weights having the highest value.

[0089] Example 18 includes an open radio access network as described in any one of Examples 14-17, wherein the second circuitry of the master unit is configured to transmit the resource block to the radio unit subset only via multicast to the radio unit subset having a subset of the antenna elements corresponding to: (1) the first subset of coefficients of the channel estimate having the highest value or (2) the second subset of coefficients of the proposed beamforming weight having the highest value.

[0090] Example 19 includes an open radio access network as described in any one of Examples 14-18, wherein the second circuitry of the master unit is configured to derive precoder weights for user equipment in the open radio access network based on the channel estimate or the proposed beamforming weights received from the distributed unit.

[0091] Example 20 includes the open radio access network of any one of Examples 14-19, and further includes: the distributed unit including a third circuit system configured to: receive resource block groups; and select which user equipment to reuse based on the resource block groups.

Claims

1. A master unit for use in an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), the master unit comprising: The circuit system is configured to: Resource blocks are received from the distributed units of the open radio access network that implements multi-user multiple-input multiple-output (MU-MIMO); Receive channel estimates or suggested beamforming weights from the distributed unit; Examine one of the following: (1) the channel estimation, to associate a first coefficient of the channel estimation with a corresponding antenna element of the plurality of radio units, or (2) the proposed beamforming weights, to associate a second coefficient of the proposed beamforming weights with the corresponding antenna element of the plurality of radio units; Select a subset of antenna elements, the subset of antenna elements corresponding to: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weight having the highest value; The derived beamforming weights to be applied to the resource block are determined based on: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weights having the highest value; The derived beamforming weights are applied to the resource block; as well as The resource block is transmitted to a subset of radio units, the subset of radio units having the subset of antenna elements corresponding to: (1) a first subset of coefficients of the channel estimate having the highest value or (2) a second subset of coefficients of the proposed beamforming weight having the highest value.

2. The main unit according to claim 1, further comprising the circuit system configured such that: Receive the channel estimate from the distributed unit; The channel estimate is examined to associate the first coefficient of the channel estimate with the corresponding antenna element of the plurality of radio units; Select the first subset of antenna elements corresponding to the coefficients of the channel estimate having the highest value; The derived beamforming weights to be applied to the resource block are determined based on the first subset of coefficients of the channel estimate having the highest value. The derived beamforming weights are applied to the resource block; as well as The resource block is transmitted to the radio unit subset of the antenna element subset having coefficients corresponding to the channel estimate having the highest value.

3. The main unit according to claim 2, wherein the circuit system is configured as follows: Receive the channel estimate as a channel matrix; and The channel estimate is examined by checking the coefficients of the channel matrix to associate each coefficient of the channel matrix with the corresponding antenna element of the plurality of radio units.

4. The main unit of claim 1, further comprising the circuit system configured such that: Receive the proposed beamforming weights from the distributed unit; The proposed beamforming weights are examined to associate the second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; Select the second subset of antenna elements corresponding to the coefficients of the proposed beamforming weights having the highest value; The derived beamforming weights to be applied to the resource block are determined based on a second subset of the coefficients of the proposed beamforming weights having the highest value. The derived beamforming weights are applied to the resource block; as well as The resource block is transferred to the radio unit subset of the antenna element subset having coefficients corresponding to the proposed beamforming weights having the highest values.

5. The main unit of claim 1, wherein the circuit system is configured to transmit the resource block to the radio unit subset having only a multicast to the radio unit subset having the following: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value.

6. The main unit according to claim 1, wherein the circuit system is configured to: The precoder weights of the user equipment in the open radio access network are derived based on the channel estimation or the proposed beamforming weights received from the distributed unit.

7. A method for use in an open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), the method comprising: Resource blocks are received from distributed units at the master unit of the open radio access network; At the main unit, channel estimation or suggested beamforming weights are received from the distributed unit; At the main unit, check one of the following: (1) the channel estimation, to associate a first coefficient of the channel estimation with a corresponding antenna element of the plurality of radio units, or (2) the proposed beamforming weight, to associate a second coefficient of the proposed beamforming weight with the corresponding antenna element of the plurality of radio units; At the main unit, a subset of antenna elements is selected, the subset of antenna elements corresponding to: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weight having the highest value; At the main unit, the derived beamforming weights to be applied to the resource block are determined based on: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weights having the highest value; The derived beamforming weights are applied to the resource block; as well as The resource block is transmitted from the master unit to a subset of radio units, the subset of radio units having a subset of antenna elements corresponding to: (1) a first subset of coefficients of the channel estimation with the highest value or (2) a second subset of coefficients of the proposed beamforming weight with the highest value.

8. The method according to claim 7, further comprising: The channel estimate is received from the distributed unit at the main unit; The channel estimate is checked at the main unit to associate the first coefficient of the channel estimate with the corresponding antenna element of the plurality of radio units; At the main unit, select the first subset of antenna elements corresponding to the coefficients of the channel estimate having the highest value; At the main unit, the derived beamforming weights to be applied to the resource block are determined based on the first subset of the coefficients of the channel estimate having the highest value; The derived beamforming weights are applied to the resource block at the main unit; as well as The resource block is transferred from the master unit to the radio unit subset of the antenna element subset having coefficients corresponding to the channel estimate having the highest value.

9. The method according to claim 8, further comprising: The channel estimate is received as a channel matrix at the main unit. as well as The channel estimate is checked at the main unit by examining the coefficients of the channel matrix to associate each coefficient of the channel matrix with the corresponding antenna element of the plurality of radio units.

10. The method of claim 8, further comprising: Receive resource block groups at the distributed unit; as well as At the distributed unit, a user equipment is selected for reuse based on the resource block group.

11. The method of claim 7, further comprising: The proposed beamforming weights are received from the distributed unit at the main unit. The proposed beamforming weights are checked at the main unit to associate the second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; At the main unit, select the second subset of antenna elements corresponding to the coefficients of the proposed beamforming weights having the highest value; At the main unit, the derived beamforming weight to be applied to the resource block is determined based on a second subset of the coefficients of the proposed beamforming weight having the highest value; The derived beamforming weights are applied to the resource block at the main unit; as well as The resource block is transferred from the master unit to the radio unit subset of the antenna element subset having coefficients corresponding to the proposed beamforming weights having the highest magnitude.

12. The method of claim 7, wherein the transmission of the resource block from the master unit to the radio unit subset is performed using multicast only to the radio unit subset having the following: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value.

13. The method of claim 7, further comprising: The precoder weights of the user equipment in the open radio access network are derived based on the channel estimation or the proposed beamforming weights received from the distributed unit.

14. An open radio access network implementing multi-user multiple-input multiple-output (MU-MIMO), the open radio access network comprising: A plurality of radio units, each of which includes a first circuit system for exchanging radio frequency signals with at least one user equipment; as well as A main unit communicatively coupled to the plurality of radio units, the main unit including a second circuit system configured to: Receive resource blocks from the distributed unit; Receive channel estimates or suggested beamforming weights from the distributed unit; Examine one of the following: (1) the channel estimation, to associate a first coefficient of the channel estimation with a corresponding antenna element of the plurality of radio units, or (2) the proposed beamforming weights, to associate a second coefficient of the proposed beamforming weights with a corresponding antenna element of the plurality of radio units; Select a subset of antenna elements, the subset of antenna elements corresponding to: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weight having the highest value; The derived beamforming weights to be applied to the resource block are determined based on: (1) a first subset of the coefficients of the channel estimate having the highest value or (2) a second subset of the coefficients of the proposed beamforming weights having the highest value; The derived beamforming weights are applied to the resource block; as well as The resource block is transmitted to a subset of radio units of the plurality of radio units, the subset of radio units having a subset of antenna elements corresponding to: (1) a first subset of coefficients of the channel estimation having the highest value or (2) a second subset of coefficients of the proposed beamforming weight having the highest value.

15. The open radio access network of claim 14, further comprising the second circuitry of the main unit being configured such that: Receive the channel estimate from the distributed unit; The channel estimate is examined to associate the first coefficient of the channel estimate with the corresponding antenna element of the plurality of radio units; Select the first subset of antenna elements corresponding to the coefficients of the channel estimate having the highest value; The derived beamforming weights to be applied to the resource block are determined based on the first subset of coefficients of the channel estimate having the highest value. as well as The resource block is transmitted to the radio unit subset of the antenna element subset having coefficients corresponding to the channel estimate having the highest value.

16. The open radio access network of claim 15, wherein the second circuit system of the main unit is configured to: Receive the channel estimate as a channel matrix; and The channel estimate is examined by checking the coefficients of the channel matrix to associate each coefficient of the channel matrix with the corresponding antenna element of the plurality of radio units.

17. The open radio access network of claim 14, further comprising the second circuitry of the main unit being configured such that: Receive the proposed beamforming weights from the distributed unit; The proposed beamforming weights are examined to associate the second coefficient of the proposed beamforming weights with the corresponding antenna elements of the plurality of radio units; The derived beamforming weights to be applied to the resource block are determined based on a second subset of the coefficients of the proposed beamforming weights having the highest value. The derived beamforming weights are applied to the resource block; as well as The resource block is transferred to the radio unit subset of the antenna element subset having coefficients corresponding to the proposed beamforming weights having the highest values.

18. The open radio access network of claim 14, wherein the second circuitry of the master unit is configured to transmit the resource block to the radio unit subset only via multicast to the radio unit subset having the following: (1) the first subset of the coefficients of the channel estimate having the highest value or (2) the second subset of the coefficients of the proposed beamforming weight having the highest value.

19. The open radio access network of claim 14, wherein the second circuitry of the master unit is configured to derive the precoder weights of the user equipment of the open radio access network based on the channel estimation or the proposed beamforming weights received from the distributed unit.

20. The open radio access network of claim 14, further comprising: The distributed unit includes a third circuit system, which is configured to: Receive resource block group; as well as Based on the resource block group, select which user equipment to reuse.

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