Multicast efficiency improvements in o-ran fronthaul

Abstract

Systems and methods for multicast efficiency improvements in O-RAN fronthaul are described herein. In certain embodiments, a network system includes one or more intermediate nodes. The network system also includes a plurality of radio units, wherein the intermediate nodes provide data to the plurality of radio units, and wherein the plurality of radio units are grouped into a plurality of groups, where each group has a different combination of radio units in the plurality of radio units and an associated multicast address. Additionally, when the data is to be provided to multiple radio units in the plurality of radio units, the intermediate nodes are configured to identify one or more groups in the plurality of groups associated with the multiple radio units and use associated multicast addresses for the one or more groups to direct the data only to the multiple radio units in the one or more groups.

Description

MULTICAST EFFICIENCY IMPROVEMENTS IN O-RAN FRONTHAULCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States Provisional Patent Application Serial No. 63 / 672,143 entitled “MULTICAST EFFICIENCY IMPROVEMENTS IN O-RAN FRONTHAUL” filed on July 16, 2024, which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Wireless communications service providers are deploying 5G radio access networks (RANs). Such 5G radio access networks are configured to satisfy the open radio access network (O-RAN) Alliance specifications (“O-RAN specifications”). The O-RAN specifications include, without limitation, the O-RAN fronthaul working group control, user and synchronization plane specification (O-RAN-WG4.CUS.0- R003-V15.00) and O-RAN Alliance working group 4 management plane specification (0-RAN-WG4.MP.0-R003-vl5.00); the O-RAN specifications are hereby incorporated by reference herein in their entirety.

[0003] The O-RAN specifications permit interoperability of RAN components, e.g., O-RAN specification compliant radios (or O-RAN radio units or O-RAN radios) and O-RAN specification compliant distributed units (or O-RAN distributed units), made by different vendors. The O-RAN distributed unit may be executed on a server system, e.g., local server network(s) and / or cloud computing system(s). The O-RAN distributed unit (O-DU) may comprise virtual baseband unit(s)). The O-RAN specifications utilize message protocols to communicate between remote radio units and virtual baseband units that differ from those used in legacy systems, e.g., 4G specification compliant radio access networks (or 4G radio access networks). A virtual baseband unit processes, e.g.. encodes, baseband data received from and sent to the radio(s). A radio transmits and / or receives data at one or more frequencies translated above baseband. The virtual baseband unit and radio(s) are components of a communications system such as a cellular communications system.

[0004] Systems following the O-RAN specification may be used to provide communication services within a shared cell, where the system is provided by a neutral host. In particular, multiple mobile network operators (MNOs) may be connected to a single communication system to provide communication serviceswithin the coverage area associated with the shared cell. The different MNOs may use different communication hardware to connect to the shared cell communication system, and the communication system may use various radio units provided by the neutral host to communicate with user equipment within the coverage area provided by the system.SUMMARY

[0005] Systems and methods for multicast efficiency improvements in O-RAN fronthaul are described herein. In certain embodiments, a network system includes one or more intermediate nodes. The network system also includes a plurality of radio units, wherein the one or more intermediate nodes provide data to the plurality of radio units, and wherein the plurality of radio units are grouped into a plurality of groups, where each group has a different combination of radio units in the plurality of radio units and an associated multicast address. Additionally, when the data is to be provided to multiple radio units in the plurality of radio units, the one or more intermediate nodes are configured to identify one or more groups in the plurality of groups associated with the multiple radio units and use associated multicast addresses for the one or more groups to direct the data only to the multiple radio units in the one or more groups.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Drawings accompany this description and depict only some embodiments associated with the scope of the appended claims. Thus, the described and depicted embodiments should not be considered limiting in scope. The accompanying drawings and specification describe the exemplary embodiments, and features thereof, with additional specificity and detail, in which:

[0007] FIG. 1 is a block diagram illustrating a shared network system according to an aspect of the present disclosure according to an aspect of the present disclosure;

[0008] FIG. 2 is a block diagram illustrating a shared network system with multicast fronthaul efficiency improvements according to an aspect of the present disclosure;

[0009] FIG. 3 is a diagram illustrating an exemplary radio unit group record and modifications according to an aspect of the present disclosure; and

[0010] FIG. 4 is a flowchart diagram of a method for improving multicast efficiency in an O-RAN fronthaul according to an aspect of the present disclosure.

[0011] Per common practice, the drawings do not show the various described features according to scale, but the drawings show the features to emphasize the relevance of the features to the example embodiments.DETAILED DESCRIPTION

[0012] The following detailed description refers to the accompanying drawings that form a part of the present specification. The drawings, through illustration, show specific illustrative embodiments. However, it is to be understood that other embodiments may be used and that logical, mechanical, and electrical changes may be made.

[0013] In O-RAN, a base station is typically implemented in a disaggregated manner in which each base station is partitioned into at least one central unit (CU), at least one distributed unit (DU), and one or more radio units (RUs). Used herein, the terms “north” or “northbound” mean “upstream” or toward the DU, while the terms “south” or “southbound” mean “downstream” or away from the DU.

[0014] The O-RAN specifications define a “shared cell” configuration or implementation in which a single cell is served using multiple RUs. The O-RAN shared cell implementation attempts to make more efficient use of bandwidth to and from DUs (compared to O-RAN 1 .0) in order to support communicating front-haul data with the multiple RUs. The O-RAN shared cell implementation is described in detail at Section 13 “Support of Shared Cell,” in the O-RAN Working Group 4 (Open Fronthaul Interfaces WG) Control. User and Synchronization Plane Specification version 10.0 from October 2022 (0-RAN.WG4.CUS.0-R003-vl5.00, hereinafter “Support of Shared Cell O-RAN Specification”, available at pages 295-314 of PDF at https: / / specifications.o-ran.org / specifications ), which is incorporated herein byreference.

[0015] In the O-RAN shared cell implementation, there are generally two modes of operation in the fronthaul: Fronthaul Multiplexer (FHM) mode and Cascade mode. Examples of implementing a shared cell include an FHM in order to more efficiently support one-DU-to-many-RU mapping. In examples, the FHM: (1) replicates the downlink packet stream (from the DU) for each RU; and (2) uses combining / digitalsummation on the uplink packet stream from the RUs (before sending to the DU). The combining / digital summation includes: (1) adding the corresponding in-phase (I) samples in corresponding physical resource blocks (PRBs) (from all the RUs); (2) adding the corresponding quadrature-phase (Q) samples in corresponding PRBs (from all the RUs); and (3) sending a combined stream of I / Q data from the FHM to the DU. The combining / digital summation may optionally include some overflow management. Using the shared cell implementation, the DU can send and receive a single packet stream (with a bandwidth of approximately N PRBs) instead of M packet streams (one for each RU with a total bandwidth of approximately N PRBs x M RUs). By reducing the DU transmitted and received data to a single stream of N PRBs, the shared cell implementation reduces bandwidth (between the DU and multiple RUs).

[0016] An FHM may be limited in how many RUs can connect to it (such as no more than 8 RUs in some examples). In some implementations, multiple FHMs are cascaded from one another to support larger quantities of RUs. In some examples, each FHM implements front-haul transport functionality and does not include radio functionality for transmitting and receiving RF signals with UEs. In some examples, multicast is used in the downlink to reduce fronthaul bandwidth, and unicast is used in the uplink.

[0017] In the typical O-RAN shared cell configuration, RUs associated with a DU utilize the same frequency resources simultaneously. By deploying multiple smaller, low-power RUs, a broad coverage area can be achieved despite each RU having limited individual coverage. Within these broad coverage areas. UEs are typically within a smaller coverage area of a subset of all the RUs associated with the DU. The spatial arrangement of smaller coverage areas associated with the RUs enables the simultaneous reuse of frequency resources across multiple RUs, provided each UE and the coverage areas provided by the corresponding RUs are sufficiently isolated in radio coverage from one another. As used herein, a frequency resource may refer to a portion of the frequency spectrum, such as a resource block, that can be used for communication between the RU and a connected UE.

[0018] When the spatial arrangement allows for the reuse of frequency resources, DUs can coordinate simultaneous downlink (DL) transmission and uplink (UL) combining using RUs that are in communication with the scheduled UEs. Thecoordination can optimize energy consumption and enhance the aggregated capacity within the available channel bandwidth. Thus, the reuse and enabled coordination can significantly boost the efficiency of utilizing the costly spectrum.

[0019] To coordinate the simultaneous reuse of resources, a DU may communicate through the fronthaul to subsets of RUs using either TP unicast or IP broadcast methods. Using a unicast approach (sending each destination RU an individual message) causes s calability issues. In particular, when using IP unicast, a DU must replicate packets intended for multiple RUs in an RU group serving a UE for each RU in the RU group. As there are several RU groups serving different UEs, using unicast quickly multiplies the number of communications from the DU, which can cause the DU to fail to meet transmission time interval (TTI) guarantees. Thus, to ensure that the DU and the associated system satisfy the TTI guarantees, the DU may perform IP multicast (such as IPv6 multicast or IPv4 broadcast) using FHM.

[0020] However, using the IP multicast causes all the RUs to receive CU-plane packets meant for RUs through the fronthaul. Accordingly, each RU performs some processing on the packets to determine if they are an intended recipient for the transmission, or if the transmission was intended for another RU. For example, a network interface controller (NIC) may process the received message and provide the message to the RU to determine whether the RU is an intended recipient. As each RU performs this processing for CU-plane packets transmitted through the IP multicast regardless of whether the RU is an intended recipient, using IP multicast can lead to high amounts of IP layer overhead, and the capacity requirements of the NIC for each RU will be multi-fold (network bandwidth for channel capacity times the number of reuse), causing an increase in the hardware cost per RU.

[0021] Systems and methods described herein resolve these issues while performing reuse of frequency resources. In particular, the RUs are grouped into defined RU groups, where each RU group has a unique IP multicast address (like IPv6 multicast address). The DU and any nodes between the DU and the RU transmit the CU-plane data only to the RUs in the defined RU group. Further, to determine what RUs are in the RU groups when a cell is commissioned, the RU groups may be initialized statically by organizing the RUs within the cell coverage area into different groups and allocating a unique multicast IPv6 address for each group. For example, each of the RUs may be paired with each other into different RU groups, and then eachunique pair of RUs will be assigned a unique multicast address. When transmitting CU-plane data to the RUs, the network structure will use the IP multicast addresses to send the CU-plane data to only the RUs in the RU group with the IP multicast address.

[0022] Additionally, it is possible that some of the provisioned RU groups are never used. For example, the positioning of some RUs may cause some pairs of RUs to never jointly transmit data to the same UE. Also, it is possible that different pairs of RUs often receive the same joint transmission. For example, a UE may be positioned such that it is in communication with more than a single pair of RUs. Accordingly, to increase efficiency, network components can adjust the RU groups as the system is used to more accurately reflect the layout, design, and use of the network. In particular, network components, like a DU or other node, may maintain a time-series record of the mapping between UEs and the corresponding RUs used. Using this statistical time-series data, a recommender system within one or more nodes of the network may prune unused RU groups, determine appropriate sizes of RU groups, and create / modify RU groups with sets of frequently used RU combinations. As the statistical recording and inference-based group assignment would auto-correct the groups to reflect the layout, design, and use of the network throughout the life of the system, the system will constantly improve fronthaul efficiency.

[0023] FIG. 1 is a block diagram illustrating an example of a communication system 100. In the example shown in FIG. 1, the communication system 100 is implemented using an 0-RAN or other point-to-multipoint distributed base station architecture. The communication system 100 may also be referred to here as an ‘"O-RAN” or an “O- RAN system.” In some examples, communication system 100 includes one or more central units 101 at least one distributed unit (DU or O-DU) 103, one or more intermediate nodes / switches 105-1 - 105-3 (referenced herein generally as intermediate nodes / switches 105), at least one system manager 109, and one or more radio units (RU or O-RU) (such as radio unit (RU) 107-1 and any quantity of optional radio unit (RU) 106-2 through optional radio unit (RU) 107-X, referenced herein generally as RU(s) 107) configured to serve at least one user equipment (UE) 111-1 — 111-M (referenced herein generally as UE(s) 111) within the site at hich wireless services is being provided.

[0024] In some examples, the at least one CU 101 and at least one DU 103 may implement a “base station." “base station entity;’ or “base station system” (which in the context of a fourth generation (4G) Long Term Evolution (LTE) system, may also be referred to as an “evolved NodeB,” “eNodeB,” or “eNB”; in the context of a fifth generation (5G) New Radio (NR) system, may also be referred to as a “gNodeB” or “gNB”; and may take different names in other current or future generations of radio access networks (RAN) and communication networks). In some examples, the at least one CU 101 and / or at least one DU 103 are located remotely from the site at which wireless service is being provided, e.g., in centralized banks of nodes. In optional embodiments, some of the functionality of the CU 101 and DU 103 may be implemented as part of a baseband controller 106 located at a site, where the baseband controller 106 communicates with a device management system such as the system manager 109. Additionally, the RUs 107 may be physically separated from each other at the site at which wireless service is being provided, although they are each communicatively coupled to the one or more DUs 103 via the at least one fronthaul network 113. A base station may be used to provide UEs 111 with mobile access to a mobile network operator’s (MNO) core network 115 to enable UEs 1 11 to wirelessly communicate data and voice (using, for example, Voice over LTE (VoLTE) technology or a 3GPP 5G RAN providing wireless service using a 5G air interface).

[0025] In certain embodiments, the communication system 100 implements a base station as a respective 5GNR gNB. In such a configuration, each CU 101 implements Layer 3 and non-time critical Layer 2 functions for the 5GNR gNB. In examples, each CU 101 may be further partitioned into at least one control -plane entity (“CU- CP”) and at least one user-plane entity' (“CU-UP”) that handles the control-plane and user-plane processing of the CU 101, respectively. In examples, each DU 103 is configured to implement the time-critical Layer 2 functions and, except as described below, at least some of the Layer 1 functions for the gNB. In this example, each RU 107 is configured to implement the physical layer functions for the gNB that are not implemented in the DU 103, as well as the RF interface. Further, in some implementations, the intermediate nodes / s witches 105 may also perform some of the Layer 2 or physical layer functions. Also, each RU 107 includes or is coupled to a respective set of one or more antennas used to radiate downlink RF signals to UEs 111 and receive uplink RF signals transmitted by UEs 111.

[0026] In general, the communication system 100 is configured to provide wireless service to various items of user equipment (UEs) 110 (such as user equipment (UE) 110-1 and any quantify of optional user equipment (UE) 110-2 through optional user equipment (UE) 110-B). Unless explicitly stated to the contrary', references to Layer 1, Layer 2, Layer 3, and other or equivalent layers (such as the Physical Layer or the Media Access Control (MAC) Layer) refer to layers of the particular wireless interface (for example. Fourth Generation (4G) Long Term Evolution (LTE) or Fifth Generation (5G) New Radio (NR)) used for wirelessly communicating with UEs 110. Furthermore, it is also to be understood that 5GNR 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. Moreover, although some embodiments are described here 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.

[0027] In examples, the at least one CU 101 is communicatively coupled to at least one corresponding core network 115 of the associated wireless operator via at least one backhaul network 117. The at least one backhaul network 117 is typically a public wide area network such as the Internet, though it is understood that the at least one backhaul network 117 can be implemented in other ways. In examples, at least one DU 103 is communicatively coupled to at least one CU 101 via at least one midhaul network. In examples, the midhaul interface promulgated by the O-RAN Alliance is used for the midhaul network between the DU 103 and the at least one CU 101. In examples, at least one RU 107 is communicatively coupled to at least one DU 103 via at least one fronthaul network 113. In examples, the fronthaul interface promulgated by the O-RAN Alliance is used for the fronthaul network 113 between each RUs 107 and the respective DU 103. In examples, each of the backhaul network 117, the midhaul network, and / or the fronthaul network 113 may be implemented with one or more switches, routers, and / or other networking devices. For example, the fronthaul network 113 may include the intermediate node / s witches 105. In some examples, the backhaul network 117, the midhaul network, and / or the fronthaul network 113 may be implemented with switched Ethernet using a switched Ethernet network and an Ethernet switch.

[0028] Although FIG. 1 (and the description set forth herein more generally) is described in the context of 5G embodiments where each logical base station entity is partitioned into a CU 101, DUs 103, and RUs 107 and, for at least some of the physical channels, some physical-layer processing is performed in the DUs 103 with the remaining physical-layer processing being performed in the RUs 107 or intermediate node / switches 105, it is to be understood that the techniques described here can be used with other wireless interfaces (for example, 4G LTE) and with other ways of implementing a base station entity (for example, using a conventional baseband band unit (BBU) / remote radio head (RRH) architecture). Accordingly, references to a CU, DU, or RU in this description 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 of the functions or features described here as being implemented by a CU, DU, or RU.

[0029] Each CU 101, DU 103, intermediate nodes / switches 105, and RUs 107 and any of the specific features described here as being implemented thereby, can be implemented in hardware, software, or combinations of hardware and software, and the various implementations (whether hardware, software, or combinations of hardware and software) can also be referred to generally as “circuitry,” a “circuit,” or “circuits” that is or are configured to implement at least some of the associated functionality. When implemented in software, such software can be implemented in software or firmware executing on one or more suitable programmable processors (or other programmable device) or configuring a programmable device (for example, processors or devices included in or used to implement special-purpose hardware, general-purpose hardware, and / or a virtual platform). In such a software example, the software can comprise program instructions that are stored (or otherwise embodied) on or in an appropriate non-transitory storage medium or media (such as flash or other non-volatile memory, magnetic disc drives, and / or optical disc drives) from which at least a portion of the program instructions are read by the programmable processor or device for execution thereby (and / or for otherwise configuring such processor or device) in order for the processor or device to perform one or more functions described here as being implemented the software. Such hardware or software (or portions thereof) can be implemented in other ways (for example, in a field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc.).

[0030] Moreover, each CU 101, DU 103, intermediate nodes / switches 105. and RUs 107, can be implemented as a physical network function (PNF) (for example, using dedicated physical programmable devices and other circuitry) and / or a virtual network function (VNF) (for example, using one or more general purpose servers (possibly with hardware acceleration) in a scalable cloud environment and in different locations within an operator's network (for example, in the operator’s ‘"edge cloud” or “central cloud”). Each VNF can be implemented using hardware virtualization, operating system virtualization (also referred to as containerization), and application virtualization, as well as various combinations of two or more of the preceding. Where containerization is used to implement a VNF, it may also be referred to as a “containerized network function” (CNF). For example, in the exemplary embodiment shown in FIG. 1, each RU 107 and FHM is implemented as a PNF and is deployed in or near a physical location where radio coverage is to be provided and each CU 101 and DU 103 is implemented using a respective set of one or more VNFs deployed in a distributed manner within one or more clouds (for example, within an “edge” cloud or “central” cloud). Each CU 101, DU 103. intermediate nodes / switches 105, and RUs 107, and any of the specific features described here as being implemented thereby, can be implemented in other ways.

[0031] The links shown in the communication system 100 in FIG. 1 show all the RUs 107 being connected to the fronthaul network 113 (which could be implemented with one or more intermediate nodes / switches 105, which may include switches, routers, and / or other networking devices). The actual physical links between devices in the backhaul network 117, the midhaul network, and / or the fronthaul network 113 may be implemented using different media, such as conductive media (copper, multi-rate, multi-mode cables, etc.) and optical media (fiber optic cables). In examples, each RU 107 and each physical node on which each DU 103 is implemented includes one or more Ethernet network interfaces to couple each RU 107 and each physical node implementing the DU 103 to the fronthaul network 113 in order to facilitate communications between the DU 103 and the RUs 107.

[0032] The RUs 107 may be deployed at a site to provide wireless coverage and capacity for one or more wireless netw ork operators. The site at which wireless service is being provided may cover, for example, a building or campus or other grouping of buildings (used, for example, by one or more businesses, governments, orother enterprise entities) or some other public venue (such as a hotel, resort, amusement park, hospital, shopping center, university campus, arena, or an outdoor area such as a ski area, stadium or a densely populated downtown area). In some configurations, the site at which wireless service is being provided is at least partially (and optionally entirely) indoors, but other alternatives are possible.

[0033] Each UE 111 may be a computing device with at least one processor that executes instructions stored in memory', e.g., a mobile phone, tablet computer, mobile media device, mobile gaming device, laptop computer, vehicle-based computer, desktop computer, etc.

[0034] Each CU 101, DU 103. intermediate node / switch 105. and RU 107 can be implemented so as to use an air interface that supports one or more of frequencydivision duplexing (FDD) and / or time-division duplexing (TDD). Also, the CU 101, DUs 103. intermediate node / switch 105, and RUs 107 can be implemented to use an air interface that supports one or more of the multiple-input-multiple-output (MIMO), single-input-single-output (SISO), single-input-multiple-output (SIMO), and / or beam forming schemes. For example, the CU 101, DUs 103, and RUs 107 can implement one or more of the 5G NR transmission modes. Moreover, the communication system 100 can be configured to support multiple air interfaces and / or to support multiple wireless operators.

[0035] In examples in the downlink, the DU 103 communicates downlink controlplane messages, downlink user-plane messages, and uplink control-plane messages to the RU 107-1, which uses the downlink control-plane and do vnlink user-plane messages to wirelessly transmit downlink radio frequency signals using a respective set of antennas for reception by UEs 110.

[0036] In examples in the uplink, the RUs 106 wirelessly receive uplink radio frequency signals transmitted from UEs 111 using a respective set of antennas and generate uplink user-plane data from the received RF signals. In examples, an intermediate node / switch 105 may also combine user data received from the RUs 107. In examples, the combining is an uplink summation. In examples, the combining is uplink coherent combining that requires phase information for the data.

[0037] In examples in the uplink, for each uplink slot, the serving DU 103 schedules one or more UEs 111 to transmit during that slot. In examples, the DU 103 sendsuplink control-plane messages to each RU 107 identifying the resource blocks (RBs) for which the RU 107 should provide baseband IQ data. The RBs for which the RU 107 should provide baseband IQ data are also referred to here as ‘'front-hauled RBs.”

[0038] In embodiments where the baseband IQ data communicated over the fronthaul comprises frequency -domain baseband IQ data, the front-hauled RBs comprise only those RBs that have been assigned to the scheduled UEs 111 for uplink transmissions during that slot. In embodiments where the baseband IQ data communicated over the fronthaul comprises time-domain baseband IQ data, the front-hauled RBs comprise all of the RBs for the slot (due to the time-domain nature of the baseband IQ data).During each uplink slot, for each antenna port, each RU 107 generates respective baseband IQ data for each front-hauled RB from an uplink RF analog signal received via a respective one of the antennas associated with that RU 107. For each RU 107, for each uphnk slot, the RU 107 generates an uplink user-plane message that includes the baseband IQ data generated at that RU 107 for the various front-hauled RBs and antenna ports and communicates the uphnk user-plane messages northbound.

[0039] Each CU 101, DU 103, intermediate node / switch 105, and RU 107, and any of the specific features described here as being implemented thereby, can be implemented in other ways. Additionally, it should be noted that the systems and methods described herein may also be used in other distributed RANs, e.g.. a distributed antenna system (DAS).

[0040] In additional embodiments, the DU 103 and intermediate node / switches 105 may implement fronthaul multiplexers (FHM). For example, FHM functionality may be integrated into the DU 103, one or more of the intermediate node / switches 105, or one or more of the RUs 107. Alternatively, one or more of the intermediate node / switches may operate as independent FHMs.

[0041] In embodiments employing FHM, the DU 103 may replicate downlink packet streams (from the DU) for each RU 107. Also, intermediate nodes / switches 105 may use combining / digital summation on the uplink packet stream from the RUs 107 (before sending to the DU). The combining / digital summation includes: (1) adding the corresponding in-phase (I) samples in corresponding physical resource blocks (PRBs) (from all the connected RUs 107); (2) adding the corresponding quadrature-phase (Q) samples in corresponding PRBs (from all the connected RUs 107); and (3) sending acombined stream of I / Q data from the node employing FHM to the DU 103. The combining / digital summation may optionally include some overflow management. Using the shared cell implementation, the DU 103 can send and receive a single packet stream (with a bandw idth of approximately N PRBs) instead of M packet streams (one for each RU 107 with a total bandwidth of approximately N PRBs x M RUs). By reducing the transmitted to and received data from the RU 107 to a single stream of N PRBs. the employment of FHM within a shared cell implementation more efficiently uses the available bandwidth.

[0042] In additional embodiments, the system 100 may include a system manager 109 that communicates with the various components of the system 100 that are deployed within a system. The system manager 109 may function as a network management system that performs configuration management of the system components, fault management, performance management, resource provisioning, and software management. The system manager 109 may communicate the various components of the system 100 through ethemet connections, wireless communication links, and the like. The system manager 109 may allow a neutral host to manage the use of the components of the system 100 by one or more MNOs.

[0043] FIG. 2 is a block diagram of a system 200 that limits the transmission of CU plane data to only intended RUs 207a - 207g (referred to herein generally and collectively as RU(s) 207). Each RU 207 may function similarly to the RUs 107 described above in connection with FIG. 1. As shown, the system 200 includes an intermediate node / s witch 205 in communication with multiple base stations 224. As disclosed above, each base station 224 may include a DU 103, CU 101. and other hardware used to connect the system 200 to a core network 115 of a mobile netw ork operator.

[0044] Further, the intermediate nodes / swdtches 205 may include any nodes or devices that may combine signals in the uplink direction and disseminate signals to the RUs 207 in the downlink direction. For example, an intermediate node / switch 205 may be an aggregate switch. As used herein, an aggregate switch facilitates the aggregation and combining of uplink data from any southbound RUs 207 and nodes 205 and routes data to the appropriate RU 207. An intermediate node / switch 205 may be equipped with processing capabilities to handle various volumes of data, supporting different protocols and other functions to support the aggregation androuting of data. In particular, an intermediate node / s witch 205 may route data or subsets of data based on data contained in messages to be sent to the particular RUs 207.

[0045] By routing information to different RUs 207 in a shared cell configuration, RUs associated with a DU (such as DU 103) may utilize the same frequency resources simultaneously. By deploying multiple smaller, low-power RUs 207, a broad coverage area can be achieved despite each RU 207 having limited individual coverage. Within these broad coverage areas, UEs 111 are typically within a smaller coverage area of a subset of all the RUs 207 associated with the DU 103. The spatial arrangement of smaller coverage areas associated with the RUs 207 enables the simultaneous reuse of frequency resources across multiple RUs 207, provided each UE 111 and the coverage areas provided by the corresponding RUs 207 are sufficiently isolated in radio coverage from one another. As used herein, a frequency resource may refer to a portion of the frequency spectrum, such as a resource block, that can be used for communication between the RU 207 and a connected UE 111.

[0046] When the spatial arrangement allows for the reuse of frequency resources, DUs 103 can coordinate simultaneous downlink (DL) transmission and uplink (UL) combining using RUs 207 that are in communication with the scheduled UEs 111. The coordination can optimize energy consumption and enhance the aggregated capacity within the available channel bandwidth. Thus, the reuse and enabled coordination can significantly boost the efficiency of utilizing the costly spectrum.

[0047] To coordinate the simultaneous reuse of resources, a DU 103 may communicate through the fronthaul to subsets of RUs 207 using either IP unicast or IP broadcast methods. However, using unicast to communicate with the RUs 207 creates scaling issues. For example, when using IP unicast, a DU 103 must replicate packets intended for multiple RUs 207 in a group of RUs 207 serving a UE 111 for each RU 207 in the group. As there are several groups of RUs 207 serving different UEs 111, using unicast quickly multiplies the number of communications from the DU 103 through the fronthaul, which can cause the DU 103 to fail to meet transmission time interval (TTI) guarantees. Thus, to ensure that the DU 103 and the associated system satisfy the TTI guarantees, the DU 103 may perform IP multicast (such as IPv6 multicast or IPv4 broadcast) using FHM.

[0048] In certain embodiments, IP multicast can be used to control the routing of control-plane data and user-plane data to one or more of the connected RUs 207. For example, the DU 103 or one or more of the intermediate nodes / s witches 205 may insert routing information into the header of the data to be transmitted that the intermediate nodes 205 can use to route the CU-plane data to the appropriate RUs 207. For example, the intermediate nodes 205 may use IPv4 or IPv6 information to direct information to different RUs. When creating the custom header or other types of routing information like signature vectors, the intermediate nodes / s witches 205 may receive data from a base station 224 and identify destination information in the data (such as IP addresses) associated with the destination RUs 207 for the data. With the IP address information in the header, the intermediate nodes / s witches 205 may direct the packet along the paths associated with the destination IP addresses in the header of the transport packet for the control-plane data or the user-plane data. As such, only the RUs 207 associated with the IP address are able to receive the packet, reducing the amount of data communicated through the fronthaul network 113.

[0049] However, using IP multicast may lead the RUs 207 associated with the DU 103 to receive CU-plane packets meant for only some of the RUs 207 through the fronthaul 1 13. Accordingly, each RU 207 may perform some processing on the packets to determine if they are an intended recipient for the transmission or if the transmission was intended for another RU 207. For example, a network interface controller (NIC) on an RU 207 may process the received message and provide the message to the RU 207 to determine whether the RU 207 is an intended recipient. As each RU 207 performs the processing for CU-plane packets transmitted through the IP multicast regardless of whether the RU 207 is an intended recipient, using IP multicast can lead to high amounts of IP layer overhead and the capacity requirements of the NIC for each RU 207 will be multi-fold (network bandwidth for channel capacity times the number of reuse), causing an increase in the hardware cost per RU 207.

[0050] To more effectively leverage multicast advantages while reducing processing by non-intended RUs 207 when performing frequency reuse. In particular, the DU 103 and / or intermediate nodes / switches 205 may maintain an RU group record 210 of various RU groups within the system 200. Each RU group defined in the RU group record 210 may have a unique IP multicast address (like IPv6 multicast address). TheDU 103 and any intermediate nodes / switches 205 between the DU 103 and the RUs 207 transmit the CU-plane data only along the communication paths to the RUs 207 in the RU group associated with the IP multicast address defined in the RU Group Record 210. Thus, only those RUs 207 in the defined RU group will receive the CU plane data.

[0051] In some embodiments, when initially commissioning the system 200, the layout of the system 200 may be largely unknown. Also, it may be difficult to determine how to determine what groups of RUs 207 would likely communicate with a prospective UE 111 within the coverage area. As such, when commissioned, the RUs 207 may be initialized / organized into different RU groups in a systematic manner, and then each RU group is allocated a unique multicast IPv6 address. For example, each initial group may include a pair of RUs, and the different RU groups within the system 200 may represent each potential pair of RUs 207.

[0052] FIG. 3 represents a potential implementation of an RU group record 210 and how the RU group record 201 may change throughout the operation of the system 200. In particular, FIG. 3 illustrates an initial RU group record 321 and operational modifications 323 that illustrate modifications that may occur to the RU group record 210 over the operation of the system 200. As illustrated in FIG. 2, the system 200 includes multiple RUs 207a - 207g. As illustrated, the initial RU group record 321 may include a listing of each potential pair of RUs for the RUs 207a - 207g.Returning to FIG. 2, while the initial grouping has been described as the different pair combinations of RUs 207, the initial grouping of RUs in the RU group record 210 may be different organizations of RUs 207. For example, the initial grouping could be based on combinations of different numbers of RUs 207 (three, four, or mixed combinations). Also, when layout information is known, the initial grouping of the RUs 207 may take into account the layout of the RUs 207 within the coverage area. For example. RUs 207 may be grouped with other RUs 207 that are on the same floor or within a certain distance of each other.

[0053] In certain embodiments, after performing the initial grouping of RUs 207, each resultant RU group may be assigned a unique multicast address. The resultant information contained in the RU group record 210 may be communicated to the various intermediate nodes / switches 205 in the system 200 through the management plane. In some embodiments, the RU group record 210 may be created andmaintained by the system manager 109 and then communicated to the components of the system 200. Alternatively, the RU group record 210 may be automatically generated by a node in the intermediate nodes / switches 205 and then disseminated to the other intermediate node / switches 205 in the system 200. With the information in the RU group record 210, the network structure of the system 200 uses the IP multicast addresses associated with specified RU groups in the RU group record to send CU-plane data to only the RUs in the RU groups associated with specified IP multicast addresses.

[0054] In some embodiments, as the initial grouping of RUs represented in the RU group record may be agnostically generated with respect to the actual layout of the system 200, it is possible or likely that some of the provisioned RU groups are never used. For example, the positioning of some RUs 207 within the system 200 may cause some pairs of RUs 207 to never jointly transmit data to the same UE 111. Also, it is possible that more than a single pair of RUs 207 often receive the same joint transmission. For example, a UE 111 may be positioned such that it is in communication with more than a single pair of RUs 207. Accordingly, to increase efficiency, network components in the system 200 can adjust the RU groups specified in the RU group record 210 to more accurately reflect the layout, design, and use of the network. In particular, network components, like a DU 103 or other intermediate node / switches 105, may store time-series data 220 of the mapping between UEs 111 and the RUs 207 used to communicate with UEs. This information may be used to identify RU groups that more accurately represent the layout, design, and use of the RUs 207 in the system 200.

[0055] In some embodiments, the system 200 may include a recommender system 230. The recommender system 230 may be stored on one or more of the intermediate nodes / switches 205, on the system manager 109, or on other computing devices within the system 200. The recommender system 230 analyzes the time-series data 220 to determine w hether changes should be made to the RU groups defined in the RU group record 210. Potential changes include pruning RU groups, altering the size of RU groups, and creating or modifying RU groups to cause the RU groups defined in the RU group record 210 to reflect the sets of frequently used combinations of RUs 207. For example, the recommender system 230 may use the time-series data 220 to identify7RU groups defined in the RU group record 210 that are unused and thenprune the unused RU groups from the RU group record 210. The recommender system 230 may also identify combinations of RU groups that are used as reflected in the time-series data 220. From the combinations of RU groups that are used, the recommender system may create new RU groups or modify existing RU groups.

[0056] The representation of the RU group record 210 in FIG. 3 also illustrates modifications 323 made by the recommender system 230. For example, the time series data may reflect that multiple RU groups created in the original provisioning of RU groups are not used. For example, the time series data may reflect that RUs in the combination, including RUs 207a, 207b, and 207c, are never communicating with UEs in combination with any of the RUs 207e, 207f, and 207g. Accordingly, groups reflecting these combinations may be pruned from the RU group record by the recommender system 230. Additionally, the time-series data 220 may reflect multiple groups of RUs 207 not reflected in the RU group record 210 are in communication with the same UE 111. For example, the recommender system 230 may determine from the time-series data that a UE 111 may be in communication with RUs 207a, 207b. and 207c. Also, the recommender system 230 may determine that the RU group including 207a, 207b, 207c, and 207d; the RU group including 207b, 207c. and 207d; the RU group including 207d, 207e, and 207f; and the RU group including 207e, 207f, and 207g may each potentially be in communication with the same UE 111. As such, the recommender system 230 may add them to the RU group record 210 or modify RU groups in the RU group record 210 to reflect these commonly used RU groups.

[0057] The use of a recommender system that functions by performing statistical analysis of the time-series data 220 may adjust the RU groups to reflect the layout and use of the RUs 207 when communicating with UEs 111. As the system 200 uses the RU groups and associated multicast addresses to reduce CU plane data to RUs not communicating with particular UEs 111, the system 200 reduces the computational load on the RUs and reduces fronthaul traffic.

[0058] FIG. 4 is a flow chart diagram of a method 400 for improving multicast efficiency in an O-RAN fronthaul. The method 400 proceeds at 401, where at least one transmission of data is received at an intermediate node in a communication network. Further, the method 400 proceeds at 403, where one or more radio units that are the recipients of the at least one transmission of data are identified. Also, themethod proceeds at 405, where one or more radio unit groups containing the one or more radio units are identified. For example, an intermediate node or other device may find the one or more radio units in a radio unit group record, and then identify the one or more radio unit groups that reflect the one or more radio units. Further, the intermediate node may then identify the one or more multicast addresses associated with the one or more radio unit groups. Additionally, the method 400 proceeds at 407, where one or more multicast addresses associated with the one or more radio unit groups are identified. Moreover, the method 400 proceeds at 409, where the at least one transmission of data is multicast to the one or more radio unit groups using the one or more multicast addresses.Example Embodiments

[0059] Example 1 includes a network system comprising: one or more intermediate nodes; and a plurality of radio units, wherein the one or more intermediate nodes provide data to the plurality of radio units, and wherein the plurality of radio units are grouped into a plurality of groups, where each group has a different combination of radio units in the plurality of radio units and an associated multicast address; wherein when the data is to be provided to multiple radio units in the plurality of radio units, the one or more intermediate nodes are configured to identify one or more groups in the plurality of groups associated with the multiple radio units and use associated multicast addresses for the one or more groups to direct the data only to the multiple radio units in the one or more groups.

[0060] Example 2 includes the network system of Example 1, wherein the data is at least one of control-plane data and user-plane data.

[0061] Example 3 includes the network system of any of Examples 1-2, wherein information describing the plurality of groups and the associated multicast addresses is stored in a radio unit group record.

[0062] Example 4 includes the network system of Example 3, wherein at least one of the one or more intermediate nodes and a system manager for the network system are configured to store time-series data, where the time-series data identifies which radio units in the plurality of radio units are simultaneously communicating with user equipment and when the radio units are communicating with the user equipment.

[0063] Example 5 includes the network system of Example 4, wherein the at least one of the one or more intermediate nodes and the system manager implement a recommender system, wherein the recommender system is configured to adjust the radio unit group record based on the time-series data.

[0064] Example 6 includes the network system of Example 5, wherein the recommender system is configured to adjust the radio unit group record by performing at least one of: pruning a radio unit from one or more radio unit groups in the radio unit group record; adding a new radio unit to the one or more radio unit groups in the radio unit group record: modifying the one or more radio unit groups in the radio unit group record; and creating one or more new radio unit groups in the radio unit group record.

[0065] Example 7 includes the network system of any of Examples 3-6, wherein an initial group of radio units identified within the radio unit group record contains a listing of the plurality of radio units separated into possible combinations of radio unit pairs.

[0066] Example 8 includes the network system of any of Examples 3-7, wherein the associated multicast addresses are automatically generated and provided to at least one of the one or more intermediate nodes and the radio units through a management plane.

[0067] Example 9 includes the network system of any of Examples 1-8, wherein the associated multicast address is an IPv6 multicast address.

[0068] Example 10 includes a method comprising: receiving at least one transmission of data at an intermediate node in a communication network; identifying one or more radio units that are recipients of the at least one transmission of data; identifying one or more radio unit groups containing the one or more radio units; identifying one or more multicast addresses associated with the one or more radio unit groups; and multicasting the at least one transmission of data to the one or more radio unit groups using the one or more multicast addresses.

[0069] Example 11 includes the method of Example 10, wherein the at least one transmission of data is at least one of control-plane data and user-plane data.

[0070] Example 12 includes the method of any of Examples 10-11. wherein identify ing the one or more radio unit groups and the one or more multicast addressescomprises: finding the one or more radio units in a radio unit group record; identifying the one or more radio unit groups in the radio unit group record that reflect the one or more radio units; and identifying the one or more multicast addresses in the radio unit group record associated with the one or more radio unit groups.

[0071] Example 13 includes the method of Example 12, further comprising storing time-series data, wherein the time-series data identifies radio units simultaneously communicating with a user equipment and when the radio units communicating with the user equipment.

[0072] Example 14 includes the method of Example 13, further comprising adjusting the radio unit group record based on the time-series data.

[0073] Example 15 includes the method of Example 14, wherein adjusting the radio unit group record comprises at least one of: pruning a radio unit from the one or more radio unit groups in the radio unit group record; adding a new radio unit to the one or more radio unit groups in the radio unit group record; modifying the one or more radio unit groups in the radio unit group record; and creating one or more new radio unit groups in the radio unit group record.

[0074] Example 16 includes the method of any of Examples 12-15. further comprising creating an initial grouping of radio units in the radio unit group record, wherein the initial grouping of radio units identifies a pair of radio units, and the initial grouping of radio units contains each potential pair of radio units.

[0075] Example 17 includes the method of any of Examples 12-16, further comprising transmitting the radio unit group record to one or more intermediate radio nodes through a management plane.

[0076] Example 18 includes the method of any of Examples 10-17, wherein the one or more multicast addresses are IPv6 multicast addresses.

[0077] Example 19 includes a system comprising: a plurality of radio units; and one or more intermediate nodes, wherein the one or more intermediate nodes are configured to: receive at least one transmission of data; identify7one or more radio units that are recipients of the at least one transmission of data; identify one or more radio unit groups containing the one or more radio units in a radio unit group record; identify one or more multicast addresses associated with the one or more radio unitgroups in the radio unit group record; and multicast the at least one transmission of data to the one or more radio unit groups using the one or more multicast addresses.

[0078] Example 20 includes the system of Example 19, further comprising a recommender system configured to adjust the radio unit group record based on timeseries data reflecting which radio units in the plurality of radio units are simultaneously communicating with user equipment and when the one or more radio units are communicating with the user equipment, wherein the recommender system is configured to adjust the radio unit group record by performing at least one of: pruning a radio unit from the one or more radio unit groups in the radio unit group record; adding a new- radio unit to the one or more radio unit groups in the radio unit group record; modifying the one or more radio unit groups in the radio unit group record; and creating one or more new radio unit groups in the radio unit group record.

[0079] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims

CLAIMSWhat is claimed is:

1. A network system comprising: one or more intermediate nodes; and a plurality of radio units, wherein the one or more intermediate nodes provide data to the plurality of radio units, and wherein the plurality of radio units are grouped into a plurality of groups, where each group has a different combination of radio units in the plurality7of radio units and an associated multicast address; wherein when the data is to be provided to multiple radio units in the plurality of radio units, the one or more intermediate nodes are configured to identify one or more groups in the plurality of groups associated with the multiple radio units and use associated multicast addresses for the one or more groups to direct the data only to the multiple radio units in the one or more groups.

2. The network system of claim 1, wherein the data is at least one of controlplane data and user-plane data.

3. The network system of claim 1, wherein information describing the plurality of groups and the associated multicast addresses is stored in a radio unit group record.

4. The network system of claim 3, wherein at least one of the one or more intermediate nodes and a system manager for the network system are configured to store time-series data, where the time-series data identifies which radio units in the plurality of radio units are simultaneously communicating with user equipment and when the radio units are communicating with the user equipment.

5. The network system of claim 4, wherein the at least one of the one or more intermediate nodes and the system manager implement a recommender system, wherein the recommender system is configured to adjust the radio unit group record based on the time-series data.

6. The netw ork system of claim 5, wherein the recommender system is configured to adjust the radio unit group record by performing at least one of: pruning a radio unit from one or more radio unit groups in the radio unit group record;adding a new radio unit to the one or more radio unit groups in the radio unit group record; modifying the one or more radio unit groups in the radio unit group record; and creating one or more new radio unit groups in the radio unit group record.

7. The network system of claim 3, wherein an initial group of radio units identified within the radio unit group record contains a listing of the plurality of radio units separated into possible combinations of radio unit pairs.

8. The network system of claim 3, wherein the associated multicast addresses are automatically generated and provided to at least one of the one or more intermediate nodes and the radio units through a management plane.

9. The network system of claim 1, wherein the associated multicast address is an IPv6 multicast address.

10. A method comprising: receiving at least one transmission of data at an intermediate node in a communication network; identifying one or more radio units that are recipients of the at least one transmission of data; identifying one or more radio unit groups containing the one or more radio units; identifying one or more multicast addresses associated with the one or more radio unit groups; and multicasting the at least one transmission of data to the one or more radio unit groups using the one or more multicast addresses.

11. The method of claim 10, wherein the at least one transmission of data is at least one of control-plane data and user-plane data.

12. The method of claim 10, wherein identifying the one or more radio unit groups and the one or more multicast addresses comprises: finding the one or more radio units in a radio unit group record;identifying the one or more radio unit groups in the radio unit group record that reflect the one or more radio units; and identifying the one or more multicast addresses in the radio unit group record associated with the one or more radio unit groups.

13. The method of claim 12, further comprising storing time-series data, wherein the time-series data identifies radio units simultaneously communicating with a user equipment and when the radio units are communicating with the user equipment.

14. The method of claim 13, further comprising adjusting the radio unit group record based on the time-series data.

15. The method of claim 14, wherein adjusting the radio unit group record comprises at least one of: pruning a radio unit from the one or more radio unit groups in the radio unit group record; adding a new radio unit to the one or more radio unit groups in the radio unit group record; modifying the one or more radio unit groups in the radio unit group record; and creating one or more new radio unit groups in the radio unit group record.

16. The method of claim 12, further comprising creating an initial grouping of radio units in the radio unit group record, wherein the initial grouping of radio units identifies a pair of radio units, and the initial grouping of radio units contains each potential pair of radio units.

17. The method of claim 12, further comprising transmitting the radio unit group record to one or more intermediate radio nodes through a management plane.

18. The method of claim 10, wherein the one or more multicast addresses are IPv6 multicast addresses.

19. A system comprising: a plurality of radio units; andone or more intermediate nodes, wherein the one or more intermediate nodes are configured to: receive at least one transmission of data; identify one or more radio units that are recipients of the at least one transmission of data; identify one or more radio unit groups containing the one or more radio units in a radio unit group record; identify one or more multicast addresses associated with the one or more radio unit groups in the radio unit group record; and multicast the at least one transmission of data to the one or more radio unit groups using the one or more multicast addresses.

20. The system of claim 19, further comprising a recommender system configured to adjust the radio unit group record based on time-series data reflecting which radio units in the plurality of radio units are simultaneously communicating with user equipment and when the one or more radio units are communicating with the user equipment, wherein the recommender system is configured to adjust the radio unit group record by performing at least one of: pruning a radio unit from the one or more radio unit groups in the radio unit group record; adding a new radio unit to the one or more radio unit groups in the radio unit group record; modifying the one or more radio unit groups in the radio unit group record; and creating one or more new radio unit groups in the radio unit group record.

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