Open radio access network with unified remote units supporting multiple functional divisions, multiple wireless interface protocols, multiple generations of radio access technologies, and multiple radio frequency bands

Abstract

One embodiment is directed to an open radio access network for providing radio coverage for multiple cells at a field, comprising a virtualized headend including one or more base station nodes and multiple unified remote units deployed at the field. Each of the unified remote units can support multiple functional divisions, multiple air interface protocols, multiple generations of radio access technologies, and multiple frequency bands. The unified remote unit and functional division used to service each cell can be changed (e.g., on the fly as part of an automatic or manual adaptation process that is a function of one or more monitored performance attributes of the open radio access network, such as network bandwidth, network latency, processing load, or processing performance). The unified remote unit can be implemented in a modular manner, including a backplane to which different radio modules can be coupled.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of Indian Provisional Patent Application No. 2020 / 41027733 (Attorney Docket No. 4445 IN PR / 100.1897INPR) filed on June 30, 2020, titled "OPEN RADIO ACCESS NETWORK WITH UNIFIED REMOTE UNITS SUPPORTING MULTIPLE FUNCTIONAL SPLITS, MULTIPLE WIRELESS INTERFACE PROTOCOLS, MULTIPLE GENERATIONS OF RADIO ACCESS TECHNOLOGY, AND MULTIPLE RADIO FREQUENCY BANDS" and Indian Provisional Patent Application No. 2020 / 41027733 (Attorney Docket No. 4445 IN PR / 100.1897INPR) filed on August 12, 2020, titled "OPEN RADIO ACCESS NETWORK WITH UNIFIED REMOTE UNITS SUPPORTING MULTIPLE FUNCTIONAL SPLITS, MULTIPLE WIRELESS INTERFACE PROTOCOLS, MULTIPLE GENERATIONS OF RADIO ACCESS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 064,557 (Attorney Docket No. 4445 US P1 / 100.1897USPR), entitled "A MICROPHONE TECHNOLOGY, AND MULTIPLE RADIO FREQUENCY BANDS," both of which are incorporated herein by reference in their entireties. [Background technology]

[0002] Fifth-generation (5G) radio access network (RAN) architectures enable a wide range of deployment options and support a wide range of 5G wireless services. 5G RAN architectures support multiple options for how RAN functions are split between centralized and distributed entities, also known as the "functional split" used in the RAN.

[0003] The 3rd Generation Partnership Project (3GPP®) has defined eight general functional division options for fronthaul networks. In the context of these 3GPP definitions, the functional division occurs between a baseband unit (BBU) (or other centralized entity) and a remote radio head (RRH) (or other distributed entity), and data is communicated between the BBU and the RRH over the fronthaul network. The nature and format of the data depends on where the functional division occurs. Unless explicitly indicated otherwise, references to a "layer" of the Open Systems Interconnection (OSI) model are to the layer used to communicate wirelessly with user equipment (UE) using the associated wireless interface.

[0004] Eight general functional partitioning options are shown in Figure 1. In Figure 1, the functions shown on the left side of the associated functional partitioning option are implemented by the BBU, and the functions shown on the right side of the associated functional partitioning option are implemented by the RRH. As shown in Figure 1, the first functional partitioning option shown in Figure 1 ("Option 1") is implemented between Layer 3 102 and Layer 2 104. That is, in Option 1, the BBU implements all of the Layer 3 functions for both the downlink and uplink (including the control plane radio resource control (RRC) function 106 and the user plane data function 108, which originate and receive data packets (e.g., Internet Protocol (IP) and User Datagram Protocol (UDP) packets)). In option 1, the RRH implements all of the functions of Layer 2 104 for both downlink and uplink (including Packet Data Convergence Protocol (PDCP) function 110, high and low Radio Link Control (RLC) functions 112 and 114, and high and low Medium Access Control (MAC) functions 116 and 118), all of the functions for Layer 1 120 for both downlink and uplink (high and low Physical Layer (PHY) functions 122 and 124), as well as Radio Frequency (RF) function 126.

[0005] As shown in FIG. 1 , a second functionality division option (“Option 2”) shown in FIG. 1 is implemented between the PDCP function 110 and the high RLC function 112. That is, in Option 2, the BBU implements all of the functionality of Layer 3 102 and the PDCP function 110 of Layer 2 104 for both the downlink and uplink. In Option 2, the RRH implements the other functionality of Layer 2 104 (including high and low RLC functions 112 and 114, and high and low MAC functions 116 and 118) for both the downlink and uplink, as well as all of the functionality of Layer 1 120 and the RF function 126 for both the downlink and uplink. As shown in FIG. 1 , a third functionality division option (“Option 3”) shown in FIG. 1 is implemented between the high RLC function 112 and the low RLC function 114 of Layer 2 104. That is, in Option 3, the BBU implements all of the functionality of Layer 3 102 for both the downlink and uplink, as well as the PDCP functionality 110 and high RLC functionality 112 of Layer 2 104. In Option 3, the RRH implements the other functionality of Layer 2 104 (including the low RLC function 114 and the high and low MAC functions 116 and 118) for both the downlink and uplink, as well as all of the functionality of Layer 1 120 and the RF functionality 126 for both the downlink and uplink.

[0006] As shown in FIG. 1 , the fourth functionality division option ("Option 4") shown in FIG. 1 is implemented between the low RLC function 114 and the high MAC function 116 of Layer 2 104. That is, in Option 4, the BBU implements the PDCP function 110 and the high and low RLC functions 112 and 114 of Layer 2 104, along with all of the functionality of Layer 3 102, for both the downlink and uplink. In Option 4, the RRH implements the other functionality of Layer 2 104 (including the high and low MAC functions 116 and 118) for both the downlink and uplink, as well as all of the functionality of Layer 1 120 and the RF function 126, for both the downlink and uplink. As shown in FIG. 1 , the fifth functionality division option ("Option 5") shown in FIG. 1 is implemented between the high and low MAC functions 116 and 118 of Layer 2 104. That is, in option 5, the BBU implements all of the functions of Layer 3 102 for both the downlink and uplink, as well as the PDCP function 110, high and low RLC functions 112 and 114, and high MAC function 116 of Layer 2 102. In option 5, the RRH implements the other functions of Layer 2 104 (including low MAC function 118) for both the downlink and uplink, as well as all of the functions of Layer 1 120 and RF function 126 for both the downlink and uplink.

[0007] As shown in FIG. 1 , a sixth functionality partitioning option ("Option 6") shown in FIG. 1 is implemented between Layer 2 106 and Layer 1 120. That is, in Option 6, the BBU implements all of the functionality of Layer 3 102 and Layer 2 104 for both the downlink and the uplink. In Option 6, the RRH implements all of the functionality of Layer 1 120 and the RF functionality 126 for both the downlink and the uplink. As shown in FIG. 1 , a seventh functionality partitioning option ("Option 7") shown in FIG. 1 is implemented between the high PHY functionality 122 and the low PHY functionality 124 of Layer 1 120. That is, in Option 7, the BBU implements all of the functionality of Layer 3 102 and Layer 2 104, and the high PHY functionality 122 of Layer 1 120 for both the downlink and the uplink. In Option 7, the RRH implements the other functions of Layer 1 120 (including low PHY functions 124) for both the downlink and uplink, as well as RF functions 126 for both the downlink and uplink. Various variations of the functional division of Option 7 exist (referred to as "Option 7.1", "Option 7.2", and "Option 7.3").

[0008] As shown in Figure 1, the eighth functionality splitting option ("Option 8") shown in Figure 1 is implemented between Layer 1 120 and RF functionality 126. That is, in Option 8, the BBU implements all of the functionality of Layer 3 102, Layer 2 104, and Layer 1 120 for both the downlink and uplink. In Option 8, the RRH implements RF functionality 126 for both the downlink and uplink.

[0009] There are different trade-offs associated with various functional splits. For example, if the fronthaul network is implemented using a switched Ethernet network and functional split of option 2 is used, some Layer 2 Ethernet functions may be implemented in the RRH, and aggregation and statistical multiplexing of user plane data packets may be performed before downlink and uplink data is communicated over the fronthaul network. This may significantly reduce the amount of data communicated over the fronthaul network. In contrast, if functional split of option 7 is used, more data will be communicated over the fronthaul network, but the high PHY functions 122 (implemented in the BBU) may be pooled and implemented using centralized processing resources, which may support, for example, sharing processing resources across many cells to promote more efficient processing resource usage.

[0010] Figure 2 is a block diagram illustrating different RAN architectures that can be used across multiple radio access technologies (RATs), for both 4G and 5G, and are band-agnostic (i.e., can be used in multiple different frequency bands ranging from sub-6 gigahertz (GHz) to millimeter (mmWave) frequency bands).

[0011] Figure 2 shows three variations of distributed radio access network (DRAN) architectures that can be used to implement 4G and 5G RANs. In the high-level DRAN architecture 202, both the BBU and RRH for a given cell are deployed in the tower, with a backhaul connection to the core network (a gateway, controller, or access node, which may be deployed in a centralized unit). In the mid-level and low-level DRAN architectures 204 and 206, the BBU is deployed in a distribution unit near the tower, with a fronthaul connection between the BBU and RRH at the tower and a backhaul connection between the BBU and the core network. In the mid-level DRAN architecture 204 shown in Figure 2, the functional division of option 2 is used between the BBU and RRH. In the low-level DRAN architecture 206 shown in Figure 2, the functional division of option 7 is used between the BBU and RRH.

[0012] Figure 2 shows two variants of a centralized radio access network (CRAN) architecture that can be used to implement 4G and 5G RAN. In the high-level CRAN architecture 208, BBU functionality is partially centralized, with some BBU functionality located in a central unit and other BBU functionality located in distributed units, with a fronthaul connection connecting the central and distributed units. In this architecture 208, the functional division of option 2 is used between the central unit and the distributed units, with Layer 3 functionality located in the central unit (along with a gateway, controller, or access node for the core network) and all of the Layer 2 functionality located in the distributed units (along with Layer 1 high PHY functions). The RRH functionality is located at the tower site, with a fronthaul connection connecting the distributed units and the tower site. In this architecture 208, the functional division of option 7 is used between the distributed units and the tower site, with Layer 1 low PHY functions and RF functions located at the tower site.

[0013] In the lower CRAN architecture 210, the BBU functionality is fully centralized, with all of the BBU functionality located in the central unit, the RRH functionality located at the tower sites, and fronthaul connections connecting the central unit and the tower sites. In this architecture 210, Option 7 functional division is used between the central unit and the tower sites, with all of the Layer 3 and Layer 2 functionality located in the central unit (along with Layer 1 high PHY functionality and access nodes for the core network) and Layer 1 low PHY and RF functionality located at the tower sites.

[0014] The amount of data transferred between the BBU and the RRH (and therefore the required fronthaul bandwidth) depends on the particular functional partitioning option used. Figure 3 illustrates various fronthaul capacity requirements for various functional partitioning options for a massive multiple-input multiple-output (MIMO) configuration using a 100 megahertz (MHz) system bandwidth and 64 transmit streams and 64 receive streams.

[0015] As shown in Figure 3, if option 6 is used for functional splitting, a fronthaul bandwidth of 3 gigabits per second (Gbps) is required. If one of the functional splitting variants of option 7 is used, the required fronthaul bandwidth varies from approximately 10 Gbps to 140 Gbps. (Note that the functional splits of options 7.2 and 7.3 are considered more realistic when deploying massive MIMO beamforming at the RRH.) If the functional split of option 8 is used (all of the PHY functions are deployed at the BBU), the required fronthaul bandwidth is 236 Gbps.

[0016] Organizations (such as the xRAN Forum and the O-RAN Alliance) are working on new fronthaul specifications based on the functional split of Option 7.2. One important aspect of the functional split of Option 7.2 is that the IQ samples communicated over the fronthaul are frequency-domain IQ samples as opposed to time-domain IQ samples (as in the legacy functional split of Option 8). In addition, these fronthaul specifications are expected to support the use of switched Ethernet networks for fronthaul connectivity.

[0017] Some RANs also include a distributed antenna system (DAS) to improve the wireless radio frequency (RF) coverage provided by one or more base stations. Historically, the DAS has interfaced with the base station using analog RF signals. The new RAN architecture described above can be used with such a DAS by interfacing the RRH or RU to the DAS using analog RF signals. Some existing DASs have the capability to interface directly with a BBU using a traditional Option 8 digital interface (such as a Common Public Radio Interface ("CPRI") digital interface or an Open Base Station Standards Initiative ("OBSAI") digital interface). However, such systems either generate analog RF signals within the DAS (which are then processed as other analog RF signals are processed) or convert digital IQ samples to a format otherwise used for digital transport of signals within the DAS's nodes. However, such existing DASs can only interface directly with a BBU using Option 8 functional splitting, which, as noted above, requires significant fronthaul bandwidth. Summary of the Invention

[0018] One embodiment is directed to an open radio access network for providing wireless coverage for multiple cells at a site. The open radio access network comprises a virtualized headend including one or more base station nodes. The open radio access network further comprises a plurality of unified remote units deployed at the site, each of which is associated with one or more antennas for wirelessly transmitting and receiving downlink and uplink radio frequency (RF) signals to and from user equipment. The plurality of unified remote units are configured to communicate with the one or more base station nodes using a switched Ethernet network. Each unified remote unit includes multiple downlink processing signal paths, multiple uplink processing signal paths, multiple downlink radio signal paths, and multiple uplink radio signal paths configured to support multiple fronthaul splits, multiple wireless interface protocols, multiple generations of radio access technologies, and multiple frequency bands.

[0019] Another embodiment is directed to a unified remote unit for use in an open radio access network for providing wireless coverage for multiple cells at a site. The open radio access network comprises a virtualized headend including one or more base station nodes. The unified remote unit comprises multiple downlink processing signal paths, multiple uplink processing signal paths, multiple downlink radio signal paths, and multiple uplink radio signal paths. The unified remote unit is configured to communicate with one or more base station nodes using a switched Ethernet network. The multiple downlink processing signal paths, multiple uplink processing signal paths, multiple downlink radio signal paths, and multiple uplink radio signal paths are configured to support multiple fronthaul splits for communicating user plane and control plane transport data to and from the base station nodes and to support multiple wireless interface protocols, multiple generations of radio access technologies, and frequency bands for communicating wirelessly with user equipment.

[0020] Another embodiment is directed to a method for providing wireless coverage for multiple cells at a site using an open radio access network, the open radio access network comprising a virtualized headend including one or more base station nodes and multiple unified remote units deployed at the site, each of the multiple unified remote units being associated with one or more antennas for wirelessly transmitting and receiving downlink and uplink radio frequency (RF) signals to and from user equipment. The method is performed for each of at least some cells served by the open radio access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band. The method includes performing, by each one or more base station nodes serving that cell, processing to generate respective digital downlink fronthaul data for that cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for that cell, and transmitting the respective digital downlink fronthaul data via a switched Ethernet network to one or more respective unified remote units serving that cell. The method further includes receiving, by each of a respective one or more unified remote units serving the cell from the switched Ethernet network, respective digital downlink fronthaul data for the cell; performing processing of the respective digital downlink fronthaul data for the cell in accordance with a respective functional split, a respective wireless interface protocol, and a respective frequency band used for the cell to generate a respective downlink analog RF signal for the cell; and wirelessly transmitting the respective downlink analog RF signal for the cell from an antenna associated with the unified remote unit.The method may include wirelessly receiving, by each of one or more respective unified remote units used to serve the cell, a respective uplink analog RF signal for the cell via an antenna associated with the unified remote unit, performing processing of the respective uplink analog RF signal in accordance with a respective functional partition, a respective wireless interface protocol, and a respective frequency band used for the cell to generate respective digital uplink fronthaul data for the cell, and transmitting the respective digital uplink fronthaul data for the cell over a switched Ethernet network to one or more base station nodes used to serve the cell. The method further includes receiving, by each of the one or more base station nodes serving the cell from the switched Ethernet network, the respective digital uplink fronthaul data for the cell and performing processing of the respective digital uplink fronthaul data for the cell in accordance with the respective functional partition, a respective wireless interface protocol, and a respective frequency band used for the cell.

[0021] Other embodiments are disclosed.

[0022] The details of various embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a block diagram illustrating eight common functional partitioning options. [Figure 2] 1 illustrates two variations of a centralized radio access network (CRAN) architecture that can be used to implement 4G and 5G RANs. [Figure 3]1 illustrates various fronthaul capacity requirements for various function splitting options for a massive multiple-input multiple-output (MIMO) configuration using a 100 megahertz (MHz) system bandwidth and 64 transmit streams and 64 receive streams. [Figure 4] 1 illustrates one exemplary embodiment of an open wireless access network with DAS features. [Figure 5] 5 illustrates one exemplary embodiment of a virtualized headend suitable for use in the open wireless access network of FIG. 4. [Figure 6] 5 illustrates one exemplary embodiment of a unified remote unit suitable for use in the open wireless access network of FIG. [Figure 7] 7 illustrates one exemplary modular implementation of the unified remote unit shown in FIG. 6. [Figure 8] 1 includes a high-level flowchart illustrating one exemplary embodiment of a method for transmitting downlink analog RF signals using an open wireless access network. [Figure 9] 1 includes a high-level flowchart illustrating one exemplary embodiment of a method for receiving an uplink analog RF signal using an open wireless access network. [Figure 10] 1 includes a high-level flowchart illustrating one exemplary embodiment of a method for adapting the operation of an open wireless access network. [Figure 11] 10 includes a high-level flowchart illustrating one exemplary embodiment of a method for optimizing the transfer of fronthaul data using Option 8 functional partitioning and time domain IQ data.

[0024] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 4 illustrates one exemplary embodiment of an open wireless access network 400 with DAS features.

[0026] As shown in Figure 4, the open wireless access network 400 shown in Figure 4 includes a virtualized headend 402 that is communicatively coupled to one or more unified remote units 404 via a switched Ethernet network 406. The unified remote units 404 are deployed throughout venues 408 to provide wireless coverage at the venues 408.

[0027] The open radio access network 400 is configured to use four different types of communication, each of which is communicated on a separate logical plane. In this case, the four types of data are user data, control data, management data, and synchronization data, which are communicated on the user plane (also referred to herein as the "U-plane"), control plane (also referred to herein as the "C-plane"), management plane (also referred to herein as the "M-plane"), and synchronization plane (also referred to herein as the "S-plane"), respectively. User data (also referred to herein as "user plane data" or "U-plane data") includes underlying data intended to be transmitted to or by end users. Control data (also referred to herein as "control plane data" or "C-plane data") includes data used in providing real-time control of functions and entities used to communicate user data. Management data (also referred to herein as "management plane data" or "M-plane data") includes data used to implement non-real-time control and management of functions and entities used to communicate user data. Synchronization data (also referred to herein as synchronization plane data or S-plane data) includes data used in synchronizing functions and entities used to communicate user data.

[0028] Figure 5 illustrates one exemplary embodiment of a virtualized headend 402 suitable for use in the open wireless access network 400 of Figure 4. In the embodiment shown in Figure 5, the virtualized headend 402 comprises a plurality of heterogeneous base station nodes 500. The virtualized headend 402 is "virtualized" in the sense that not all of the base station nodes 500 are deployed locally at the venue 408 where wireless coverage is provided, but may be deployed remotely from the venue 408.

[0029] For each cell served by the open radio access network 400, one or more base station nodes 500 transmit and receive user plane and control plane data for that cell, and for each cell served by the open radio access network 400, the associated one or more base station nodes 500 also communicate with nodes in the service provider's core network.

[0030] The base station nodes 500 of the virtualized headend 402 are heterogeneous in that one or more base station nodes 500 used to serve a first cell are configured to transmit and receive user plane and control plane data in a format that differs from the format in which one or more base station nodes 500 used to serve a second cell are configured to transmit and receive user plane and control plane data. Also, each one or more base station nodes 500 used to serve different cells may be configured to support different RF bands and / or different wireless interface protocols.

[0031] As shown in FIG. 5 , for at least one cell served by the open wireless access network 400, one or more base station nodes 500 used to serve that cell include one or more base station nodes 502 configured to interface with a DAS using an analog RF interface. This type of base station node is also referred to herein as an “analog RF interface base station node” 502. Such an analog RF interface base station node 502 may be implemented, for example, using an RRH 505 deployed at the venue 408, and an associated BBU 503 may be co-located with the RRH 505 at the venue 408 or deployed remotely from the venue 408. In such an example, the RRH 505 may be coupled to the BBU 503 using a suitable fronthaul interface (e.g., using a legacy CPRI interface implemented over one or more fibers). Such an analog RF interface base station node 502 may also be implemented in other manners (e.g., using a single-node small cell base station (e.g., femtocell) deployed at the venue 408, with the corresponding BBU 503 and RRH 505 functionality enclosed within a common housing). Such analog RF interface base station nodes 502 may be implemented using legacy wireless interface protocols (e.g., older commercial cellular wireless interface protocols such as second generation (2G), third generation (3G), or fourth generation (4G) wireless interface protocols, and older third party radio or other public safety wireless interface protocols such as Terrestrial Electrical and Telecommunications (TETRA) wireless interface protocols). Such analog RF interface base station nodes 502 may be implemented using new base station equipment that supports new wireless interface protocols (e.g., 5G wireless interface protocols).Examples of such new base station equipment include distributed base station equipment that uses a proprietary fronthaul interface between the BBU 503 and RRH 505 functions, or a single node base station, or access point that has only an external backhaul interface and an external analog RF antenna interface. Such analog RF interface base station nodes 502 may be implemented in other manners.

[0032] 5, for at least one cell served by the open wireless access network 400, one or more base station nodes 500 used to serve that cell may include one or more base station nodes 504 configured to interface with a DAS using a digital interface. These types of base station nodes are also referred to herein as “digital interface base station nodes” 504.

[0033] The digital interface base station node 504 may be implemented using base station equipment typically used to provide 5G services. In one 5G example shown in FIG. 5, the digital interface base station node 504 includes a central unit (CU) 506 and / or a distributed unit (DU) 508 that conform to one or more specifications defined by the O-RAN Alliance. (“O-RAN” is an acronym for “open RAN.”) Such CUs 506 and DUs 508 are also referred to herein as O-RAN CUs 506 and O-RAN DUs 508, respectively. For example, for a given cell served by the open radio access network 400, both the respective O-RAN CU 506 and O-RAN DU 508 for that cell may be deployed at the site 408, or the O-RAN CU 508 for that cell may be deployed at the site 408 with the corresponding O-RAN CU for that cell deployed remotely from the site 408. Such O-RAN CU506 and O-RAN DU508 may be used to implement one or more of the wireless interface protocols supported by the O-RAN specifications (e.g., one or more 4G wireless interface protocols or one or more 5G wireless interface protocols).

[0034] 5, a digital interface base station node 504 includes a 5G BBU 510 deployed at a field 408 without a corresponding RRH. The 5G BBU 510 supports a digital fronthaul interface typically used to provide 5G services, such as an enhanced Common Public Radio Interface (eCPRI) interface.

[0035] The digital interface base station node 504 may also be implemented using base station equipment typically used to provide 4G services. In one 4G example shown in Figure 5, the digital interface base station node 504 is implemented as or uses a 4G BBU 513 deployed at the field 408 without a corresponding RRH. The 4G BBU 513 supports a digital fronthaul interface typically used in connection with providing 4G services, such as a CPRI interface, an Open Radio Equipment (ORI) interface, or an Open Base Station Standards Initiative ("OBSAI") interface.

[0036] Although some examples of digital interface base station nodes 504 are described herein as “5G examples” or “4G examples,” it should be understood that such digital interface base station nodes 504 may be used to provide services using other wireless interface protocols in addition to, or instead of, 5G or 4G services, respectively. For example, a digital interface base station node 504 described above in connection with a 5G example may be used to provide 4G services in addition to, or instead of, 5G services. Similarly, a digital interface base station node 504 described above in connection with a 4G example may be used to provide 5G services in addition to, or instead of, 4G services. Indeed, such examples may be used to implement any of the wireless interface protocols or radio access technology generations described herein. Furthermore, it should also be understood that 5G embodiments or examples may be used in standalone and / or non-standalone modes (or other modes developed in the future), and that the description herein is not limited to any particular mode.

[0037] As described above, the virtualized headend 402 and its base station nodes 500 are communicatively coupled to the unified remote units 404 via a switched Ethernet network 406. In the exemplary embodiment described herein in connection with FIGS. 4-5 , Internet Protocol (IP) is used to communicate fronthaul data between the virtualized headend 402 and the unified remote units 404. For those base station nodes 500 that do not natively support communicating user plane and control plane data using IP packets, the virtualized headend 402 includes an IP stream transceiver to convert user plane and control plane data natively transmitted and received by those base station nodes 500 to and from IP packets for communication over the switched Ethernet network 406. For example, as shown in FIG. 5 , the virtualized headend 402 includes an IP stream transceiver 512 to convert analog RF signals natively transmitted and received by one or more analog RF interface base station nodes 502 used to service at least one cell to and from IP packets for communication over the switched Ethernet network 406. In one implementation, as part of doing this, for each downlink analog RF signal output by the analog RF interface base station node 502 via the analog RF interface, the IP stream transceiver 512 receives the downlink analog RF signal and digitizes it to generate actual digital samples. The IP stream transceiver 512 digitally downconverts the actual digital samples to generate baseband digital in-phase and quadrature (IQ) samples. The IQ data may be further filtered to select the frequency band of interest. The resulting downlink IQ data for each band is packetized as user plane IP packets and communicated over the switched Ethernet network 406 to the unified remote unit 404 serving the associated cell.

[0038] If a packet received by the unified remote unit 404 from the IP stream transceiver 512 is determined to have one or more errors, the IQ data contained in the packet may be included in or excluded from subsequent processing performed to generate the downlink RF signal transmitted by that unified remote unit 404. This decision regarding whether to include or exclude such IQ data may be made using an error handling algorithm. Criteria for excluding IQ data may include the number of errors in the packet and the frequency with which errors are received from a particular IP stream transceiver 512 (or other network element). Also, if a high percentage of packets from a particular source are lost (i.e., not received when expected), all packets from that source may be excluded from subsequent processing until such packets are again periodically received from that source.

[0039] The IP stream transceiver 512 receives uplink user plane IP packets transmitted from the unified remote units 404 serving associated cells via the switched Ethernet network 406. The IP stream transceiver 512 extracts the uplink IQ data generated at those unified remote units 404 for that band, time-aligns the uplink IQ data from those unified remote units 404, and digitally sums the corresponding IQ samples. The summing may also include scaling the uplink IQ data from one or more of the unified remote units 404 (i.e., changing the gain of some of the input uplink IQ data), scaling the resulting summed uplink IQ data (i.e., changing the gain of the output summed uplink IQ data), or implementing some type of limiter to prevent the summed uplink IQ data from exceeding the available bit width of the IQ data. If a packet received from a unified remote unit 404 is determined to have one or more errors, the IQ data included in the packet may be included in or excluded from the digital summing operation according to an error handling algorithm. Criteria for excluding IQ data may include the number of errors in a packet and how often errors are received from that unified remote unit 404. Also, if a high percentage of packets from a unified remote unit 404 (or other network element) are being lost (i.e., not received when expected), all packets from that unified remote unit 404 may be excluded from the digital summing operation until such packets are again regularly received from that unified remote unit 404.

[0040] The resulting stream of summed uplink IQ samples is digitally upconverted and converted into an uplink analog RF signal that is communicated to the appropriate analog RF interface base station node 502 via its analog RF interface.

[0041] 5, some of the digital interface base station nodes 504 do not natively support communicating user plane and control plane data using IP packets (e.g., digital interface base station nodes 504 using a legacy CPRI interface for communicating fronthaul data). The virtualized headend 402 includes an IP stream transceiver 514 for converting between digital data natively transmitted and received by those digital interface base station nodes 504 to and from IP packets for communication over the switched Ethernet network 406. Such conversion may include, for example, changing the sample rate, changing the bits per sample, changing from a synchronous interface to an asynchronous interface, or rate matching.

[0042] In one embodiment, on the downlink, for each such digital interface base station node 504, an IP stream transceiver 514 receives the corresponding digital downlink data, extracts the user plane data and control plane data, packetizes the user plane data and any required control plane data as user plane IP packets and control plane IP packets, respectively, and communicates them via the switched Ethernet network 406 to a unified remote unit 404 serving the associated cell.

[0043] If a packet received by the unified remote unit 404 from the IP stream transceiver 514 is determined to have one or more errors, the IQ data contained in the packet may be included in or excluded from subsequent processing performed to generate the downlink RF signal transmitted by that unified remote unit 404. This decision regarding whether to include or exclude such IQ data may be made using an error handling algorithm. Criteria for excluding IQ data may include the number of errors in the packet and the frequency with which errors are received from a particular IP stream transceiver 514 (or other network element). Also, if a high percentage of packets from a particular source are being lost (i.e., not received when expected), all packets from that source may be excluded from subsequent processing until such packets are again periodically received from that source.

[0044] On the uplink, for each such digital interface base station node 504, an IP stream transceiver 514 receives user plane and control plane IP packets transmitted from the unified remote units 404 serving the associated cell. The IP stream transceiver 514 extracts the user plane and control plane data generated by those unified remote units 404. If necessary, the IP stream transceiver 514 time-aligns the uplink IQ data included in the extracted user plane data and digitally sums the corresponding IQ samples. The summing may also include scaling the uplink IQ data from one or more of the unified remote units 404 (i.e., changing the gain of some of the input uplink IQ data), scaling the resulting summed uplink IQ data (i.e., changing the gain of the output summed uplink IQ data), or implementing some type of limiter to prevent the summed uplink IQ data from exceeding the available bit width of the IQ data. If a packet received from the unified remote unit 404 is determined to have one or more errors, the IQ data contained in the packet may be included in or excluded from the digital summing operation according to an error handling algorithm. Criteria for excluding IQ data may include the number of errors in the packet and the frequency with which errors are received from that unified remote unit 404. Also, if a high percentage of packets from the unified remote unit 404 (or other network element) are being lost (i.e., not received when expected), all packets from that unified remote unit 404 may be excluded from the digital summing operation until such packets are again regularly received from that unified remote unit 404.

[0045] The IP stream transceiver 514 then formats the resulting user plane data and any required control plane data according to the digital interface used by the digital interface base station node 504 and communicates the user plane and control plane data to the digital interface base station node 504 using that digital interface.

[0046] In one embodiment, before digitally summing, for each resource element (or other associated unit), the corresponding uplink IQ samples communicated from the unified remote unit 404 serving the cell, the IP stream transceivers 512 and 514 are configured to analyze the uplink IQ samples received from each individual unified remote unit 404 for that resource element (or other unit) to determine whether those samples actually carry valid data transmitted from the UE. If a sample does not carry valid data transmitted from the UE, the sample may be excluded from the digital summation process (e.g., by zeroing the sample or omitting the sample), or the value of the sample may be reduced. This analysis may be performed, for example, by comparing the samples to a threshold value, and samples are deemed to carry valid data if they are greater than the threshold value and not carry valid data if they are less than the threshold value. Other techniques may be used. In other embodiments, this type of intelligent uplink summing process is not performed; instead, corresponding uplink IQ samples communicated from the unified remote units 404 serving the associated cells are digitally summed, regardless of whether the uplink IQ samples received from each individual unified remote unit 404 actually carry valid data transmitted from the UE.

[0047] The virtualized headend 402 further comprises a multi-function time synchronization server 516. The time synchronization server 516 provides a precise time source for use in the open wireless access network 400. In the example shown in FIG. 5, the precise time source is deployed using a Global Positioning System (GPS) receiver 518 coupled to an appropriately positioned antenna 520. A GPS clock reference output by the GPS receiver 518 is provided to the time synchronization server 516. The precise time source may also be deployed in other manners. For example, the time synchronization server 516 may be configured to synchronize its local clock to a timing master clock by communicating with the master clock over a backhaul interface using a time synchronization protocol such as the Network Time Protocol (NTP) and / or the Precision Time Protocol (PTP). The time synchronization server 516 is multi-function in the sense that it is configured to provide a common precise time source to heterogeneous base station nodes 500 in different manners.

[0048] The time synchronization server 516 is configured to serve as a local, precise time source for any of the base station nodes 500 deployed at the venue 408 that require such a source. For example, the time synchronization server 516 is configured to output a GPS clock reference output that appears to be provided directly from a GPS receiver. Such a GPS clock reference output may be provided to those base station nodes 500 deployed at the venue 408 that require such a source (e.g., a BBU or femtocell or O-RAN DU typically configured to serve as a timing master for the RAN). Also, in the example shown in FIG. 5 , the IP stream transceivers 512 and 514 are coupled to the time synchronization server 516 and configured to use the time synchronization server 516 as a local, precise time source. The time synchronization server 516 includes an appropriate interface to provide such a GPS clock reference output to those base station nodes 500 that require it.

[0049] The time synchronization server 516 is also configured to serve as a timing master entity for any of the base station nodes 500 that require themselves to be synchronized to such an entity. For example, the time synchronization server 516 is configured to serve as a timing master entity for the Institute of Electrical and Electronics Engineers (IEEE) 1588 Precision Time Protocol (PTP) and Synchronous Ethernet (SyncE) and to communicate with other devices in the open radio access network 400 acting as slave entities that synchronize their clocks to the clock of the time synchronization server 516 using the PTP or SyncE protocols. For example, the time synchronization server 516 may serve as a PTP or SyncE timing master entity for those base station nodes 500 that require such a master entity (e.g., an O-RAN CU 506 or an O-RAN DU 508 configured to act as a PTP or SyncE slave entity). 4 and 5, the unified remote units 404 are configured to act as PTP slave entities, with the time synchronization server 516 serving as the PTP timing master entity, so that they can synchronize their clocks to the clock of the time synchronization server 516 using the PTP protocol. The time synchronization server 516 communicates such S-plane communications with the unified remote units 404 via the switched Ethernet network 406. Such S-plane communications between the time synchronization server 516 and the unified remote units 404 can be communicated directly from the time synchronization server 516 or via an intermediate node (e.g., via one or more of the IP stream transceivers 512 and 514).Furthermore, one or more base station nodes 500 may be configured to serve as a PTP or SyncE timing master entity for one or more other base station nodes 500 and / or one or more of the unified remote units 404 (e.g., an O-RAN DU 508 may be configured to serve as a PTP or SyncE timing master entity for such other base station nodes 500 and / or one or more of the unified remote units 404).

[0050] The time synchronization server 516 is configured to use the same time reference to serve as a local precision time source and to serve as a PTP and SyncE timing master entity, so that the various entities are synchronized to the same time reference regardless of how they are synchronized.

[0051] The virtualized head-end 402 further includes a management system 522. The management system 522 is configured to manage various elements of the open wireless access network 400. The management system 522 is coupled to various entities of the virtualized head-end 402 via local connections and / or external networks (e.g., the Internet) and to the unified remote unit 404 via a switched Ethernet network 406. The management system 522 may also be coupled to a remote management system of an associated wireless service provider. The management system 522 is configured to communicate (via the M-plane) with the various entities of the open wireless access network 400 using management protocols supported by those entities (e.g., using open protocols such as the Technical Report 069 (TR-069) protocol, Network Configuration Protocol (NETCONF), and Simple Network Management Protocol (SNMP), and / or using proprietary protocols).

[0052] As described above, user plane, control plane, management plane, and synchronization plane packets are communicated to and from the unified remote units 404 via the switched Ethernet network 406. Respective user plane and control plane data for each cell served by the open wireless access network 400 may be routed to any of one or more unified remote units 404 using standard Ethernet and IP networking features (e.g., unicast, multicast, virtual local area networks (VLANs), class of service (COS), and quality of service (QOS) features, etc.). The switched Ethernet network 406 may also be implemented using standard Ethernet cables (e.g., fiber optic cables, Ethernet CAT 5e or CAT-6 cables, etc.). Each of the base station nodes 500 (including IP transceivers 512 and 514) directly coupled to the Ethernet network 406 includes one or more Ethernet interfaces (not shown) to which an Ethernet cable is attached that is used to couple the device to the switched Ethernet network 406 (more specifically, to a port of a switch within the Ethernet network 406). Each such Ethernet interface is configured to communicate over a switched Ethernet network 406 .

[0053] 6 illustrates one exemplary embodiment of a unified remote unit 404 suitable for use in the open wireless access network 400 of FIG. 4. As described above, each unified remote unit 404 is communicatively coupled to one or more base station nodes 500 of the virtualized headend 402 via a switched Ethernet network 406. Each unified remote unit 404 includes an internal Ethernet switch 600 that couples the unified remote unit 404 to the switched Ethernet network 406. The internal Ethernet switch 600 of the unified remote unit 404 comprises one or more Ethernet interfaces to which Ethernet cables are attached that are used to couple the unified remote unit 404 to the switched Ethernet network 406 (more specifically, to ports of an access switch of the Ethernet network 406).

[0054] Downlink packets transmitted from one or more base station nodes 500 of the virtual headend 402 to each unified remote unit 404 via the switched Ethernet network 406 are received at the unified remote unit 404 and forwarded by the internal Ethernet switch 600 to the appropriate internal entity within the unified remote unit 404 for processing by it. Similarly, uplink packets are output by an internal entity within the unified remote unit 404 to the internal Ethernet switch 600, which transmits the uplink packets via the switched Ethernet network 406 to one or more base station nodes 500 of the virtual headend 402.

[0055] Unified remote unit 404 includes multiple downlink multi-protocol processing blocks 604 , multiple uplink multi-protocol processing blocks 606 , multiple downlink radio modules 605 , and multiple uplink radio modules 607 .

[0056] Each downlink multi-protocol processing block 604 comprises multiple downlink signal paths 608, each of which is configured to process downlink baseband data received from one of the base station nodes 500 in the virtualized headend 402. Each uplink multi-protocol processing block 606 comprises multiple downlink signal paths 610, each of which is configured to process uplink baseband data transmitted to one of the base station nodes 500 of the virtualized headend 402. (Also, for some cells served by the open wireless access network 400, the unified remote unit 404 is configured to operate as a single-node small cell, in which case the unified remote unit 404 does not communicate with a base station node 500 of the virtualized headend 402, but instead communicates with a node in the service provider's core network.)

[0057] The downlink and uplink multi-protocol processing blocks 604 and 606 are “multi-protocol” in the sense that each block can be used to process digital data communicated to and from the virtual headend 402 (and respective base station nodes 500) using multiple different divisions of functionality or supporting different wireless interface protocols, different generations of radio access technologies (e.g., 2G, 3G, 4G, and 5G), and / or different frequency bands.

[0058] Each signal path 608 within each downlink multi-protocol processing block 604 includes a respective IP packet receiver 612 coupled to a port of the internal Ethernet switch 600 and configured to perform Ethernet, Internet Protocol (IP), and transport protocol (such as UDP) processing on downlink packets provided from the Ethernet switch 600 to the IP packet receiver 612.

[0059] In one embodiment (described in more detail below), each IP packet receiver 612 is assigned a respective IP address and MAC address, and the internal Ethernet switch 600 is configured to forward downlink packets to the appropriate IP packet receiver 612 based on the IP address and MAC address included in each downlink packet. In such an embodiment, one or more base station nodes 500 serving a given cell may send downlink packets to a particular signal path 608 of a particular downlink multi-protocol processing block 604 by sending the downlink packet to the appropriate IP address and MAC address. In this embodiment, non-real-time control plane data, management plane data, and synchronization plane data communicated to a particular signal path 608 is extracted and forwarded by that signal path 608 to a radio monitoring and management function 666 or time synchronization slave 674 in that unified remote unit 404.

[0060] In another embodiment, each IP packet receiver 612, radio monitoring and management function 666 (described below), and time synchronization slave 674 (described below) has assigned it a respective IP address and MAC address. In such an embodiment, one or more base station nodes 500 serving a given cell may send user plane downlink and real-time control plane packets to a particular signal path 608 of a particular downlink multi-protocol processing block 604, may send non-real-time control plane and management plane downlink packets to the radio monitoring and management function 666, and may send synchronization plane downlink packets to the time synchronization slave 674 by sending various types of downlink packets to the appropriate IP address and MAC address. The internal Ethernet switch 600 is configured to forward downlink packets to the appropriate IP packet receiver 612, radio monitoring and management function 666, or time synchronization slave 674 based on the IP address and MAC address contained within each downlink packet.

[0061] In another embodiment, each unified remote unit 404 has only a single IP address and MAC address assigned to it. In such an embodiment, the internal Ethernet switch 600 is configured to perform deep packet inspection (DPI) on the downlink packets it receives to determine the signal path 608 (and associated IP packet receiver 612) along which each downlink packet should be forwarded. For example, when downlink packets are transmitted from the O-RAN DU 508, the internal Ethernet switch 600 may be configured to inspect the eCPRI or IEEE 1914.3 header contained within the Ethernet payload of each downlink packet to determine the signal path 608 (and associated IP packet receiver 612) along which each downlink packet should be forwarded. (IEEE 1914.3 refers to the IEEE standard for Radio over Ethernet (RoE) encapsulation and mapping.) The IP stream transceivers 512 and 514 may also be configured to reformat the payload of the downlink packets to facilitate the DPI performed by the internal Ethernet switch 600. In this embodiment, M-plane and S-plane downlink packets received from the virtualized headend 402 may be routed within the unified remote unit 404 based on the source MAC address contained within the packets. If the source MAC address in a received downlink packet is the MAC address of the Ethernet interface used by the management system 522, the downlink packet will be routed to the radio monitoring and management function 666 of that unified remote unit 404. Similarly, if the source MAC address in a received downlink packet is the MAC address of the Ethernet interface used by the time synchronization server 516, the downlink packet will be routed to the time synchronization slave 674 within that unified remote unit 404.

[0062] Each signal path 608 within each downlink multi-protocol processing block 604 further comprises a respective deframer 614 that receives the downlink data output by a respective IP packet receiver 612 and extracts the various types of data (e.g., user plane data, control plane data, synchronization plane data, and management plane data) communicated based on the particular functional partitioning (and fronthaul or backhaul transport protocol) that the signal path 608 is configured to support. Additionally, for some functional partitionings, how the deframer 614 extracts the various types of data depends on scheduling information provided via the control plane.

[0063] In this example, non-real-time control plane data, management plane data, and synchronization plane data communicated on the signal path 608 is forwarded to a radio monitoring and management function 666 or time synchronization slave 674 within the unified remote unit 404.

[0064] Each signal path 608 within each downlink multi-protocol processing block 604 also includes L3 / L2 / L1 processing functions 616 for the various functional divisions, wireless interface protocols, and frequency bands supported by that downlink multi-protocol processing block 604. Each signal path 608 may be configured to implement a particular functional division, wireless interface protocol, and frequency band, and the corresponding L3 / L2 / L1 processing function 616 is used in conjunction with doing so to process user plane and real-time control plane data communicated to that signal path 608. Also, for some functional divisions, the processing performed by the L3 / L2 / L1 processing function 616 depends on scheduling information provided via the control plane. Furthermore, scheduling information (and other control plane information) related to uplink processing may be forwarded to the appropriate uplink signal path 610.

[0065] In one example, the signal path 608 may be configured to implement Option 7-2 functional splitting as specified by the O-RAN Alliance for use in 5GNR wireless interfaces in sub-6 GHz frequency bands, where the L3 / L2 / L1 processing function 616 within that signal path 608 is configured to perform lower 5GNR PHY functions (e.g., resource element mapping, optional beamforming, inverse fast Fourier transform (iFFT) processing, and cyclic prefix insertion) to generate time-domain baseband IQ data.

[0066] In another example, signal path 608 may be configured to implement the Option 8 functional split specified by the CPRI specification for use with 4G wireless interfaces in sub-6 GHz frequency bands, in which case the L3 / L2 / L1 processing function 616 within that signal path 608 is configured to not perform protocol-specific L3, L2, or L1 processing on the baseband data extracted by deframer 614.

[0067] In yet another example, one or more signal paths 608 may be configured to implement a single-node 5GNR small cell gNB for use with a 5GNR wireless interface in the sub-6 GHz frequency band, in which case the L3 / L2 / L1 processing function 616 in each such signal path 608 is configured to perform all of the 5GNR L3, L2, and L1 functions for the cell served by that single-node 5GNR small cell gNB. In this example, the data communicated over the switched Ethernet network 406 (and extracted by the deframer 614) includes downlink control plane, user plane, and management plane backhaul data communicated from an associated wireless service provider's core network using an appropriate backhaul interface.

[0068] The signal path 608 may be configured to implement different functional divisions, wireless interfaces, and / or frequency bands.

[0069] Each signal path 608 within each downlink multi-protocol processing block 604 further comprises a respective time-aligned first-in, first-out (FIFO) buffer 618. Each time-aligned FIFO buffer 618 is configured to time-align the resulting downlink time-domain IQ data generated on that signal path 608 with a time reference established by the time synchronization server 516 for the open wireless access network 400 (and consequently with the downlink time-domain IQ data generated on the other signal paths 608 of the various downlink multi-protocol processing blocks 604). Each time-aligned FIFO buffer 618 accommodates different communication times from the virtualized headend 402 to the unified remote unit 404 over the switched Ethernet network 406 and different processing times through each signal path 608.

[0070] Each signal path 608 within each downlink multi-protocol processing block 604 further comprises a respective sample rate adaptation function 620. Each sample rate adaptation function 620 is configured to convert the resulting downlink time-domain IQ data generated in that signal path 608 to the input sample rate and resolution used by the downlink radio module 605 (described below). For example, the processing performed in the signal path 608 for the particular wireless interface protocol that the signal path 608 is configured to support may cause it to generate time-domain IQ data having a different sample rate and / or sample resolution than the input sample rate and resolution used by the radio module 605, in which case the sample rate adaptation function 620 converts the time-domain IQ data so that it uses the required input sample rate and resolution.

[0071] The time-aligned and sample-rate adapted downlink time-domain IQ data output by each signal path 608 in each downlink multi-protocol processing block 604 may be provided to any signal path 609 of any downlink radio module 605 via a downlink IQ stream switch 622. The downlink IQ stream switch 622 is configured to receive the time-aligned and sample-rate adapted downlink time-domain IQ data output by each signal path 608 in each downlink multi-protocol processing block 604 and provide it to the appropriate signal path 609 of the appropriate downlink radio module 605 under the control of management and control plane functions described below.

[0072] Each downlink radio module 605 includes one or more signal paths 609. In the particular exemplary embodiment shown in Figure 6, each downlink radio module 605 includes a single signal path 609, although it should be understood that each downlink radio module 605 may include multiple signal paths 609.

[0073] Each signal path 609 in each downlink radio module 605 includes a respective IQ summer / adder / combiner function 624 configured to digitally sum (or otherwise combine) different downlink time-domain IQ data streams output by different signal paths 608 of the downlink multi-protocol processing block 604. For example, different signal paths 608 may be used to generate downlink time-domain IQ data for different cells (served using different frequencies within the same wide frequency band), which are digitally summed to generate a single combined IQ data stream for further processing to generate an analog RF output comprising the RF signals for the different cells.

[0074] Each signal path 609 within each downlink radio module 605 further includes a respective sample rate conversion function 626 that converts the sample rate and / or resolution of the summed IQ data output by the summer / adder / combiner function 624 to match the input sample rate and / or resolution used by a digital-to-analog (DAC) converter 634 (described below). Each signal path 609 within each downlink radio module 605 further includes a respective digital upconversion (DUC) function 628 that is configured to digitally upconvert the IQ data output by the sample rate conversion function 626. Each signal path 609 within each downlink radio module 605 further includes a crest factor reduction (CFR) and digital predistortion (DPD) function 630 for performing CFR and DPD processing for the upconverted IQ data output by the DUC function 628. The resulting IQ data is input to the digital-to-analog converter (DAC) 634 included within each signal path 609 of each downlink radio module 605. Each DAC 634 is configured to convert the digital IQ data into a composite analog signal (comprising various component frequencies). The composite analog signal is upconverted (if necessary) to the appropriate RF band, filtered, and power amplified by RF / power amplifier (RF / PA) circuitry 636 included within each signal path 609 in each downlink radio module 605. (Upconversion to the appropriate RF band can be via the DAC 634 directly outputting the composite analog signal in the appropriate RF band, or via an analog upconverter included within the RF / PA circuitry 636.) The resulting amplified composite analog RF signals output by the various signal paths 609 of the downlink radio module 605 are input to antenna circuitry 638, which is coupled to various antennas 640 associated with the unified remote unit 404. The various antennas 640 can be implemented as external antennas or as internal antennas.

[0075] For each antenna 640, the antenna circuitry 638 is configured to combine (e.g., using one or more band combiners) the composite amplified analog RF signals output by a predetermined subset of the signal paths 609 of the downlink radio module 605 and output the resulting combined signal to that antenna 640 via a duplexer.

[0076] Each uplink radio module 607 includes one or more signal paths 611. In the particular exemplary embodiment shown in Figure 6, each uplink radio module 607 includes a single signal path 611, although it should be understood that each uplink radio module 607 may include two or more signal paths 611.

[0077] For each antenna 640, antenna circuitry 638 is configured to receive an uplink analog RF signal for a set of cells from antenna 640 via a duplexer. The uplink analog signal is split (e.g., using one or more band splitters) to feed each of a predetermined subset of signal paths 611 of uplink radio module 607, a respective uplink analog RF signal for that signal path 611.

[0078] Each signal path 611 in each uplink radio module 607 includes a respective low noise amplifier / RF (LNA / RF) circuit 642 configured to low-noise amplify, if necessary, filter, the uplink analog RF signals provided to that signal path 611, and if necessary downconvert the resulting signals to generate intermediate frequency (IF) versions of those signals.

[0079] Each signal path 611 within each uplink radio module 607 further includes a respective analog-to-digital converter (ADC) 644 that converts the analog signal output by the LNA / RF circuitry 642 into actual digital samples. (The ADC 644 may be implemented using a direct RF ADC that can receive and digitize the RF signal, in which case no analog downconversion is required.)

[0080] Each signal path 611 within each uplink radio module 607 further includes an optional downlink signal cancellation function 646 configured to digitally cancel either the corresponding downlink antenna signal output by the corresponding downlink radio module 605 or downlink intermodulation signals that have leaked into the uplink frequency band. To do this, digital samples indicative of the corresponding downlink antenna signals are generated by the RF / PA circuitry 636 of the downlink radio module 605, which outputs those downlink antenna signals (e.g., using a downconverter, filter, and ADC (not shown)). The digital samples for the corresponding downlink antenna signals are provided to the downlink signal cancellation function 646, along with the digital samples for the uplink signals, so that the downlink signal cancellation function 646 can digitally cancel either the corresponding downlink antenna signal or intermodulation signals that have leaked into the uplink signal. The downlink signal cancellation function 646 is optional and may be implemented, for example, using techniques described in U.S. Pat. No. 10,103,802, which is incorporated herein by reference.

[0081] The resulting actual digital samples for the uplink signal with the leakage signal canceled (if that option is used) are provided to a digital downconverter (DDC) 648 included in that signal path 611, which digitally downconverts the actual digital samples to generate digital baseband IQ samples. The digital baseband IQ samples are provided to a sample rate conversion function 650, which converts the sample rate and / or resolution of the digital IQ samples output by the DDC 648 to match the input sample rate and / or resolution used by an IQ multiplexer function 652 (described below).

[0082] Each signal path 611 in each uplink radio module 607 includes a respective IQ multiplexer function 652 configured to digitally filter the composite IQ sample stream output by the sample rate conversion function 650 to generate separate IQ data for different cells (served using different frequencies within the same wide frequency band). Each separate stream of uplink IQ data output by the IQ multiplexer function 652 in each signal path 611 of any uplink radio module 607 may be provided to any signal path 610 of any uplink multi-protocol processing block 606 via an uplink IQ stream switch 654. The uplink IQ stream switch 654 is configured to receive the IQ data output by each signal path 611 of any uplink radio module 607 and provide it to the appropriate signal path 610 of the uplink multi-protocol processing block 606 under the control of a management plane function described below.

[0083] Each signal path 610 within each uplink multi-protocol processing block 606 further comprises a respective sample rate adaptation function 656. Each sample rate adaptation function 656 is configured to convert the IQ data provided to that signal path 610 to the input sample rate and resolution used in the uplink baseband processing performed in that signal path 610. For example, the IQ data generated by the radio module 607 may have a different sample rate and resolution than the sample rate and resolution used in the uplink baseband processing performed in that signal path 610 for the particular wireless interface protocol that the signal path 610 is configured to support, in which case the sample rate adaptation function 656 converts the provided IQ data so that it uses the sample rate and resolution required for the uplink baseband processing.

[0084] Each signal path 610 within each uplink multi-protocol processing block 606 further includes a respective delay control buffer 658. Each delay control buffer 658 is configured to buffer uplink IQ data so that it can be provided at an appropriate rate to subsequent uplink baseband processing functions within that signal path 610. The appropriate rate for providing the uplink IQ data to subsequent uplink baseband processing functions depends on the particular functional division, wireless interface protocol, and frequency bands that the signal patch 610 is configured to support at any one time.

[0085] Each signal path 610 within each uplink multi-protocol process block 606 also includes L3 / L2 / L1 processing functions 660 for the various functional divisions, wireless interface protocols, and frequency bands supported by that uplink multi-protocol processing block 606. Each signal path 610 can be configured to implement a particular functional division, wireless interface protocol, and frequency band, and a corresponding L3 / L2 / L1 processing function 660 is used to do so. Also, for some functional divisions, the processing performed by the L3 / L2 / L1 processing function 660 depends on scheduling information provided via the control plane.

[0086] In one example, the signal path 610 may be configured to implement the Option 7-2 functional split specified by the O-RAN Alliance for use in 5GNR wireless interfaces in sub-6 GHz frequency bands, where the L3 / L2 / L1 processing function 660 within that signal path 610 is configured to perform low 5GNR PHY functions (e.g., cyclic prefix removal, fast Fourier transform (FFT) processing, port reduction, and resource element demapping) to generate uplink frequency domain baseband IQ data.

[0087] In another example, signal path 610 may be configured to implement the Option 8 functional split specified by the CPRI specification for use with 4G wireless interfaces in the sub-6 GHz frequency band, in which case the L3 / L2 / L1 processing function 660 within that signal path 610 is configured not to perform protocol-specific L3, L2, or L1 processing on the baseband data provided by the associated signal path 611 of the associated uplink radio module 607.

[0088] In yet another example, one or more signal paths 610 may be configured to implement a single-node 5GNR small cell gNB for use with a 5GNR wireless interface in the sub-6 GHz frequency band, in which case the L3 / L2 / L1 processing function 660 in each such signal path 610 is configured to perform all of the 5GNR L3, L2, and L1 functions for the cell served by that single-node 5GNR small cell gNB. In this example, the data communicated over the switched Ethernet network 406 (and generated by the L3 / L2 / L1 processing function 660) includes downlink control plane, user plane, and management plane backhaul data that is communicated to an associated wireless service provider's core network using an appropriate backhaul interface.

[0089] The signal path 610 may be configured to implement different functional divisions, wireless interfaces, and / or frequency bands.

[0090] Each signal path 610 within each uplink multi-protocol processing block 606 further comprises a respective framer 662 that receives the uplink data generated by the L3 / L2 / L1 processing function 660 and frames the uplink data according to the particular functional division (and particular fronthaul or backhaul transport protocol) that the signal path 610 is configured to support and output the framed data. Also, for some functional divisions, how the frame 662 frames the uplink data generated by the L3 / L2 / L1 processing function 660 depends on scheduling information provided via the control plane.

[0091] Each signal path 610 within each uplink multi-protocol processing block 606 includes a respective IP packet transmitter 664 configured to perform Ethernet, IP, and transport protocol (such as UDP) processing to generate uplink packets from the framed uplink data output by the framer 662. The IP packet transmitter 664 is coupled to a port of the internal Ethernet switch 600 for communicating the resulting uplink packets over the switched Ethernet network 406 to one or more base station nodes 500 of the virtual headend 402.

[0092] Each unified remote unit 404 also includes a management plane function. In the embodiment shown in FIG. 6, each unified remote unit 404 includes a radio monitoring and management function 666 that communicates with the management system 522 in the virtualized headend 402 and processes any management plane data communicated directly from the base station nodes 500 in the virtualized headend 402, as well as any non-real-time control and management plane data forwarded to it from the various downlink signal paths 608. The radio monitoring and management function 666 includes a framing / deframing configuration controller 668, an L3 / L2 / L1 configuration controller 670, and a timing alignment controller 672. The framing / deframing configuration controller 668 is configured to control and configure the deframer 614 and framer 662 included in the respective signal paths 608 and 610 of the downlink and uplink multi-protocol processing block 604 and block 606. The L3 / L2 / L1 configuration controller 670 is configured to control and configure the L3 / L2 / L1 functions 616 and 660 included within the respective signal paths 608 and 610 of the downlink and uplink multi-protocol processing blocks 604 and 606. The timing alignment controller 672 is configured to control and configure the time alignment FIFO buffer 618 and delay control buffer 658 included within the respective signal paths 608 and 610 of the downlink and uplink multi-protocol processing blocks 604 and 606.

[0093] The radio monitoring and management function 666 (and its framing / deframing configuration controller 668, L3 / L2 / L1 configuration controller 670, and timing alignment controller 672) configure various parts of the unified remote unit 404, as indicated by management plane communications from the management system 522 in the virtualized headend 402.

[0094] The unified remote units 404 also include a synchronization plane function. In the embodiment shown in FIG. 6, each unified remote unit 404 includes a timing synchronization slave function 674 that communicates with the time synchronization server 516 in the virtualized headend 402. The timing synchronization slave function 674 is configured to synchronize itself (and the common local clock and clock distribution function 676 of the unified remote units 404) to a time reference established by the time synchronization server 516 for the open wireless access network 400. In the embodiment described herein in connection with FIGS. 4-6, the timing synchronization slave function 674 is configured to synchronize itself to the time reference established by the time synchronization server 516 using the PTP or SyncE protocol. The common local clock and clock distribution function 676 is configured to provide local clock signals and data for various portions of the unified remote units 404.

[0095] The virtualized headend 402 and each unified remote unit 404 (and the functionality described as included therein), and more generally, the open wireless access system 400, and any of the specific features described herein implemented by any of the above, may be implemented in hardware, software, or a combination of hardware and software, and various implementations (whether hardware, software, or a combination of hardware and software) may also be generally referred to as a “circuit” or “circuits” configured to implement at least a portion of the associated functionality. If implemented in software, such software may be implemented in software or firmware running on one or more suitable programmable processors or may constitute a programmable device (e.g., a processor or device contained in or implemented in dedicated hardware, general-purpose hardware, and / or a virtualization platform). Such hardware or software (or portions thereof) may be implemented in other ways (e.g., as an application-specific integrated circuit (ASIC)). RF functionality may also be implemented using one or more RF integrated circuits (RFICs) and / or discrete components. The virtualized headend 402 and each unified remote unit 404, and more generally the open wireless access system 400, may be implemented in other manners, including, for example, variations in the content, order, and division of the various functions and signal paths within each unified remote unit 404.

[0096] 6, antenna 640 is implemented using an external antenna that is coupled to unified remote unit 404 using antenna circuitry 638. In an alternative embodiment, at least a portion of antenna 640 is implemented using an antenna integrated into radio modules 605 and 607 or elsewhere in each unified remote unit 404.

[0097] Figure 7 illustrates one exemplary modular implementation of the unified remote unit 404 shown in Figure 6. It is understood that the modular implementation of the unified remote unit 404 shown in Figure 7 is exemplary, and that the unified remote unit 404 shown in Figure 6 may be implemented in other manners.

[0098] 7, the unified remote unit 404 comprises a central digital board 700 and multiple radio boards 702. The central digital board 700 comprises one or more processing devices 704 (such as one or more field programmable gate arrays (FPGAs)) used to implement control plane, user plane, synchronization plane, and management plane functions (including, for example, the downlink multi-protocol processing block 604 and the uplink multi-protocol processing block 606). The processing devices 704 are also used to implement portions of the internal Ethernet switch 600, the downlink IQ stream switch 622, and the uplink IQ stream switch 654.

[0099] Each radio board 702 is used to implement multiple downlink radio modules 605 and multiple uplink radio modules 607, as well as portions of the downlink IQ stream switch 622 and uplink IQ stream switch 654 that are not implemented on the central digital board 700. Each radio board 702 may also include at least a portion of the antenna circuitry 638 and may include or be coupled to one or more antennas 640.

[0100] Each radio board 702 comprises one or more processing devices 706 (such as one or more FPGAs) used to implement the IQ summer / adder / combiner function 624, sample rate conversion function 626, DUC function 628, CFR and DPD function 630 for each downlink radio module 605, optional downlink signal cancellation function 646, DDC 648, sample rate conversion function 650, and IQ multiplexer function 652 for each uplink radio module 607, along with portions of the downlink IQ stream switch 622 and uplink IQ stream switch 654 that are not implemented on the central digital board 700. 7, the DAC 634 and RF / PA circuitry 636 of each downlink radio module 605, and the LNA / RF circuitry 642 and ADC 644 of each uplink radio module 607, as well as the antenna circuitry 638 and antenna 640, are implemented separately from one or more processing devices 706 (shown in FIG. 7 as "DAC / ADC and RF circuitry" 708). Some functionality of the downlink multi-protocol processing block 604 and the uplink multi-protocol processing block 606 may also be implemented on the radio board 702.

[0101] 7, the Ethernet interfaces of the internal Ethernet switch 600 used to couple the external ports of the internal Ethernet switch 600 to the switched Ethernet network 406 may be implemented using Ethernet interface boards 710 on which an Ethernet physical layer device 712 for each Ethernet interface is implemented. In this exemplary embodiment, other functions of the internal Ethernet switch 600 are implemented on the central digital board 700.

[0102] The central digital board 700 may be implemented as a backplane with appropriate backplane connectors to which various radio boards 702 and Ethernet interface boards 710 may be connected. This embodiment allows a common central digital board 700 to be used with different radio boards 702 configured to support different frequency bands (e.g., licensed frequency bands (e.g., sub-6 GHz and mmWave frequency bands) and unlicensed frequency bands), wireless interface protocols (e.g., 2G, 3G, 4G, 5G, TETRA, and WiFi protocols), duplexing schemes (e.g., FDD and TDD), and output power classes (e.g., 200 mW, 2 W, 20 W), as well as Ethernet cabling. This allows a modular product platform to be created. For example, a unified remote unit 404 supporting multiple frequency bands and multiple wireless interface protocols may be assembled by connecting the central digital board 700 to radio boards 702 supporting different frequency bands and wireless interface protocols. Additionally, individual radio boards 702 may be configured to support lower-order MIMO schemes (such as 2x2 MIMO or 4x4 MIMO), and multiple lower-order MIMO radio boards 702 may be used together to implement higher-order MIMO schemes (such as 4x4 MIMO or 8x8 MIMO). Typically, non-software configurable, band-dependent, protocol-dependent, duplexing scheme-dependent, and / or output power-dependent devices and circuits are included within RF / PA circuitry 636, LNA / RF circuitry 642, antenna circuitry 638, and antenna 640.

[0103] Additionally, the software configurable portions of the unified remote unit 404 can be configured or reconfigured (e.g., by configuring or reconfiguring currently loaded software and / or by loading new software) to support different functional divisions, different frequency bands, wireless interface protocols, and duplexing schemes. This configuration or reconfiguration can occur when the unified remote unit 404 is assembled or tested (e.g., by a manufacturer or system integrator), when the unified remote unit 404 is installed, or immediately after installation.

[0104] 8 includes a high-level flowchart illustrating one exemplary embodiment of a method 800 for transmitting downlink analog RF signals using the open wireless access network 400. Although an embodiment of the method 800 is described herein as being implemented using the embodiment of the open wireless access network 400 described above in connection with FIGS. 4-7, other embodiments may be implemented in other manners.

[0105] 8 are generally arranged sequentially for ease of explanation, it should be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with method 800 (and the blocks shown in FIG. 8) may occur in a different order (e.g., if at least some of the processing associated with the blocks is performed in parallel and / or in an event-driven manner). Also, it should be understood that while most standard exception handling is not described for ease of explanation, method 800 can, and typically does, include such exception handling.

[0106] The embodiment of method 800 shown in FIG. 8 is described herein as being performed for a particular cell served by the open wireless access network 400, which is referred to herein as the “current” cell.

[0107] The method 800 includes performing processing to generate digital downlink fronthaul data for the current cell according to the functional division, wireless interface protocol, and frequency band used for the current cell (block 802), and transmitting the digital downlink fronthaul data via the switched Ethernet network 406 to one or more unified remote units serving the current cell (block 804).

[0108] In a first example, one or more base station nodes 500 serving a current cell include an analog RF interface base station 502 (more specifically, a remote radio head), a corresponding BBU, and an IP stream transceiver 512. In this example, the BBU performs L3, L2, and L1 processing for an associated wireless interface protocol to generate digital downlink control plane and user plane data. The digital downlink control plane and user plane data are communicated to the remote radio head using an appropriate digital interface (e.g., CPRI). The remote radio head generates a downlink analog RF signal from the received digital downlink control plane and user plane data. The IP stream transceiver 512 converts the downlink analog RF signal natively output by the remote radio head into time-domain digital baseband data encapsulated in IP packets that are communicated over a switched Ethernet network 406 to one or more unified remote units 404 serving the associated cell.

[0109] In a second example, one or more base station nodes 500 serving the current cell include a digital interface base station node 504 (more specifically, an O-RAN DU 508). The one or more base station nodes 500 may also include a corresponding O-RAN CU 506. The O-RAN CU 506 (if used to serve the current cell) and the O-RAN DU 508 perform L3 and L2 processing and L1 high PHY functions for the associated wireless interface protocol, output digital downlink user plane frequency-domain digital IQ data and digital downlink control plane messages, and communicate them in IP packets over the switched Ethernet network 406 to one or more unified remote units 404 serving the current cell.

[0110] In a third example, one or more base station nodes 500 serving the current cell include a digital interface base station node 504 (more specifically, a CPRI BBU 510) and an IP stream transceiver 514. In this example, a corresponding CPRI RRH is not used; instead, one or more unified remote units 404 serving the current cell act as RRHs for that CPRI BBU 510. In this example, the CPRI BBU 510 performs L3, L2, and L1 processing for the associated wireless interface protocol to generate digital downlink control plane and user plane data in the form of CPRI frames. The CPRI frames are communicated to the IP stream transceiver 514 using the CPRI interface. The IP stream transceiver 514 extracts the digital downlink control plane and user plane data from the CPRI frames output by the CPRI BBU 510, encapsulates the extracted digital downlink control plane and user plane data into downlink control plane and user plane IP packets, and communicates them over the switched Ethernet network 406 to one or more unified remote units 404 serving the current cell.

[0111] The method 800 further includes receiving, by each unified remote unit 404 serving the current cell, digital downlink fronthaul data for the current cell from the switched Ethernet network 406 (block 806), processing, by the unified remote unit 404, the digital downlink fronthaul data for the current cell to generate a downlink analog RF signal for the current cell (block 808), and wirelessly transmitting the downlink analog RF signal for the current cell from an antenna 640 associated with that unified remote unit 404 (block 810). The processing of the digital downlink fronthaul data is performed according to the functional division, the wireless interface protocol, and the frequency band used for the current cell.

[0112] Each unified remote unit 404 serving the current cell receives digital downlink fronthaul data that is communicated to it over the switched Ethernet network 406 using one or more Ethernet interfaces of the unified remote unit's 404 internal Ethernet switch 600.

[0113] In the exemplary embodiment described herein in connection with the open wireless access network 400 of FIGS. 4-7, one or more signal paths 608 of one or more downlink multi-protocol processing blocks 604 and one or more signal paths 609 of one or more downlink radio modules 605 of the unified remote unit 404 are used to generate downlink analog RF signals for serving the current cell.

[0114] In this example, the internal Ethernet switch 600 forwards each packet of digital downlink fronthaul data received from one or more base station nodes 500 serving the current cell to an IP packet receiver 612 in the appropriate signal path 608 of the appropriate downlink multi-protocol processing block 604, which performs Ethernet, IP, and transport protocol processing on the received packet. A deframer 614 in that signal path 608 receives the downlink data output by the IP packet receiver 612 in that signal path 608 and extracts the various types of data being communicated based on the particular functional division (and fronthaul transport protocol) used for the current cell. In this example, non-real-time control plane data, management plane data, and synchronization plane data communicated on that signal path 608 from one or more base station nodes 500 is forwarded to a radio monitoring and management function 666 or a time synchronization slave 674 in the unified remote unit 404.

[0115] An L3 / L2 / L1 processing function 616 in signal path 608 receives the extracted downlink data output by the deframer 614 in that signal path 608 and performs the required processing for the particular functional division, wireless interface protocol, and frequency band used for the current cell. Also, for some functional divisions, how the deframer 614 extracts various types of data and / or the processing performed by the L3 / L2 / L1 processing function 616 depends on scheduling information provided via the control plane.

[0116] The resulting time domain IQ data produced by the L3 / L2 / L1 processing function 616 is further processed by the remainder of the signal paths 608. The time-aligned and sample-rate adapted time domain IQ data output by each signal path 608 used to serve the current cell may be provided via a downlink IQ stream switch 622 to the appropriate signal path 609 of the appropriate downlink radio module 605 (according to the configuration determined via the management plane).

[0117] Each signal path 609 of each downlink radio module 605 used to serve the current cell receives each time-domain IQ data stream for the current cell (and any other time-domain IQ data streams for other cells) provided to that signal path 609, digitally sums (or otherwise combines) such time-domain IQ data streams, and generates an analog RF signal for serving the current cell (and any such other cells). The resulting analog RF signal is radiated to one or more antennas 640 associated with the unified remote unit 404.

[0118] 9 includes a high-level flowchart illustrating one exemplary embodiment of a method 900 for receiving an uplink analog RF signal using the open wireless access network 400. Although an embodiment of the method 900 is described herein as being implemented using the embodiment of the open wireless access network 400 described above in connection with FIGS. 4-7, other embodiments may be implemented in other manners.

[0119] 9 are generally arranged sequentially for ease of explanation, it should be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with method 900 (and the blocks shown in FIG. 9) may occur in a different order (e.g., if at least some of the processing associated with the blocks is performed in parallel and / or in an event-driven manner). Also, while most standard exception handling has not been described for ease of explanation, it should be understood that method 900 can, and typically does, include such exception handling.

[0120] The embodiment of method 900 shown in FIG. 9 is described herein as being performed for a particular cell served by the open wireless access network 400, which is referred to herein as the “current” cell.

[0121] The method 900 includes wirelessly receiving, by each unified remote unit 404 serving the current cell, an uplink analog RF signal for the current cell via an antenna 640 associated with that unified remote unit 404 (block 902), processing the uplink analog RF signal by the unified remote unit 404 to generate digital uplink fronthaul data for the current cell (block 904), and transmitting, by the unified remote unit 404, the digital uplink fronthaul data for the current cell via a switched Ethernet network 406 to one or more base station nodes 500 used to serve the current cell (block 906). The processing of the uplink analog RF signal is performed according to the functional division, wireless interface protocol, and frequency band used for the current cell.

[0122] In the exemplary embodiment described herein in connection with the open wireless access network 400 of FIGS. 4-7, one or more signal paths 610 of one or more uplink multi-protocol processing blocks 606 and one or more signal paths 611 of one or more uplink radio modules 607 of the unified remote unit 404 are used to receive and process uplink analog RF signals to serve the current cell.

[0123] Each signal path 611 of each uplink radio module 607 used to serve the current cell receives uplink analog RF signals for the current cell via one or more antennas 640 associated with the unified remote unit 404. The signal paths 611 generate time-domain IQ data streams from the received uplink analog RF signals, which are provided via an uplink IQ stream switch 654 to the appropriate signal path 610 of the appropriate uplink multi-protocol processing block 606 (according to a configuration determined via the management plane).

[0124] For each signal path 610 within each uplink multi-protocol processing block 606 used to serve the current cell, the time-domain IQ data provided thereto is converted by a respective sample rate adaptation function 656 to have the input sample rate and resolution used for the uplink baseband processing performed in that signal path 610, and buffered by a respective delay control buffer 658 so that the time-domain IQ data can be provided at the appropriate rate to subsequent uplink processing functions in signal path 610. An L3 / L2 / L1 processing function 660 within signal path 610 receives the uplink time-domain IQ data and performs the processing required for the particular function division, wireless interface protocol, and frequency band used for the current cell. Also, for some functional divisions, the processing performed by the L3 / L2 / L1 processing functions 660 depends on scheduling information provided via the control plane, in which case the L3 / L2 / L1 configuration controller 670 in the unified remote unit 404 processes the corresponding control plane data to determine such scheduling information and appropriately configure the L3 / L2 / L1 processing functions 660.

[0125] For each signal path 610 within each uplink multi-protocol processing block 606 used to serve the current cell, a respective framer 662 frames the processed uplink data according to the particular functional partition (and particular fronthaul transport protocol) that the signal path 608 is configured to support and outputs the framed data. Also, for some functional partitions, how the framer 662 frames the processed uplink data depends on scheduling information provided via the control plane, in which case a framing / deframing configuration controller 668 within the unified remote unit 404 processes the corresponding control plane data to determine such scheduling information and configure each framer 662 appropriately.

[0126] For each signal path 610 within each uplink multi-protocol processing block 606 used to service the current cell, a respective IP packet transmitter 664 performs Ethernet, IP, and transport protocol processing to generate uplink packets from the framed uplink data output by the framer 662. The IP packet transmitter 664 is coupled to a port of the internal Ethernet switch 600 for communicating the resulting uplink packets over the switched Ethernet network 406 to one or more associated base station nodes 500 of the virtual headend 402.

[0127] The method 900 further includes receiving digital uplink fronthaul data for the current cell by one or more base station nodes 500 serving the current cell from the switched Ethernet network (block 908), and performing processing of the digital uplink fronthaul data for the current cell by the one or more base station nodes 500 serving the current cell (block 910). The processing of the digital uplink fronthaul data is performed according to the respective functional division, respective wireless interface protocol, and respective frequency band used for the current cell.

[0128] In a first example, one or more base station nodes 500 serving the current cell comprise an analog RF interface base station 502 (more specifically, a remote radio head (RRH)), a corresponding BBU, and an IP stream transceiver 512. For the functional division used in this example (option 8), one or more unified remote units 404 serving the current cell communicate time-domain digital IQ data encapsulated in IP packets to the virtualized headend 402. The IP stream transceiver 512 receives IP packets from one or more unified remote units 404, extracts the time-domain digital IQ data for each antenna carrier, digitally sums the corresponding IQ samples received for each antenna carrier from the various unified remote units 404, and converts the resulting stream of summed IQ samples for each antenna carrier into an uplink analog RF signal that is provided to the remote radio head (RRH) via the antenna interface of the RRH. For each antenna carrier, the remote radio head (RRH) generates time-domain IQ data from the uplink analog RF signal that is provided to the RRH. The RRH frames the resulting time domain IQ data received for the various antenna carriers (along with the appropriate control plane, management data plane, and synchronization plane data) into uplink CPRI frames, which are communicated to the associated BBU. The BBU receives the CPRI frames, extracts the various types of data, and performs L3, L2, and L1 processing for the wireless interface protocol used to service the current cell.

[0129] In a second example, one or more base station nodes 500 serving the current cell include a digital interface base station node 504 (more specifically, an O-RAN DU 508). The one or more base station nodes 500 may also include a corresponding O-RAN CU 506. For the functional division used in this example (option 7-2), the one or more unified remote units 404 serving the current cell generate uplink O-RAN user plane and control plane data in IP packets that are communicated to the O-RAN DU 508 of the virtualized headend 402. The O-RAN DU 508 receives the IP packets, extracts various types of data, and performs L1 high PHY functions for the wireless interface protocol used to serve the current cell, as well as any L2 and / or L3 processing (if used) not performed in the O-RAN CU 506. The resulting uplink data is communicated to the O-RAN CU 506 (if used), which performs the remaining L2 and / or L3 processing.

[0130] In a third example, one or more base station nodes 500 serving the current cell include a digital interface base station node 504 (more specifically, a CPRI BBU 510) and an IP stream transceiver 514. In this example, a corresponding CPRI RRH is not used; instead, one or more unified remote units 404 serving the current cell act as RRHs for that CPRI BBU 510. For the functional division used in this example (option 8), one or more unified remote units 404 serving the current cell communicate time-domain digital IQ data encapsulated in IP packets to an IP stream transceiver 514 in the virtualized headend 402. The IP stream transceiver 514 receives the IP packets from one or more unified remote units 404, extracts the time-domain digital IQ data for each antenna carrier, and digitally sums the corresponding IQ samples for each antenna carrier received from the various unified remote units 404. The IP stream transceiver 514 frames the resulting summed time domain IQ data received for the various antenna carriers (along with the appropriate control plane, management data plane, and synchronization plane data) into uplink CPRI frames, which are communicated to the CPRI BBU 510. The CPRI BBU 510 receives the CPRI frames, extracts various types of data, and performs L3, L2, and L1 processing for the wireless interface protocol used to service the current cell.

[0131] In the embodiments of methods 800 and 900 shown in Figures 8 and 9, one or more base station nodes 500 of the virtualized headend 402 are used to serve the cell, along with one or more unified remote units 404. However, the unified remote unit 404 may also be configured to act as a single-node small cell base station serving the cell, in which case a separate base station node 500 of the virtualized headend 402 is not used to serve the cell. Backhaul downlink and uplink communications are communicated directly to the unified remote unit 404 from the service provider's core network via the switched Ethernet network 406.

[0132] 10 includes a high-level flowchart illustrating one exemplary embodiment of a method 1000 for adapting operation of an open wireless access network. Although an embodiment of the method 1000 is described herein as being implemented using the embodiment of the open wireless access network 400 described above in connection with FIGS. 4-7, other embodiments may be implemented in other manners.

[0133] 10 are generally arranged sequentially for ease of explanation, it should be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with method 1000 (and the blocks shown in FIG. 10) may occur in a different order (e.g., if at least some of the processing associated with the blocks is performed in parallel and / or in an event-driven manner). Also, while most standard exception handling has not been described for ease of explanation, it should be understood that method 1000 can, and typically does, include such exception handling.

[0134] The method 1000 includes monitoring one or more performance attributes associated with the open wireless access network 400 (block 1002), adapting a configuration of the open wireless access network 400 based on the monitored performance attributes (block 1004), and operating the open wireless access network 400 using the adapted configuration (block 1006).

[0135] In this exemplary embodiment, the management system 522 in the virtualized head-end 402 and the radio monitoring and management function 666 in the unified remote unit 404 may be configured to monitor performance attributes, such as bandwidth and / or latency, of the switched Ethernet network 406 used to communicate data between the virtualized head-end 402 and the unified remote unit 404 and / or handle the load or throughput at the base station node 500 and / or the unified remote unit 404. The management system 522 in the virtualized head-end 402 and the radio monitoring and management function 666 may perform this monitoring directly (e.g., by themselves capturing the underlying data and performing the necessary calculations), indirectly (e.g., by communicating with other entities that have the underlying data and / or perform the necessary calculations), or a combination thereof.

[0136] One or more monitored performance attributes may be checked to see if they indicate that a configuration change is needed. For example, a configuration change may be needed if one or more monitored performance attributes do not meet established thresholds for the current configuration of the open wireless access network 400.

[0137] For example, if the monitored bandwidth and / or latency of the switched Ethernet network 406 does not meet the thresholds established for the current configuration of the open wireless access network 400, the functional partitioning used in one or more of the cells served by the open wireless access network 400 may be changed to use a functional partitioning that is less bandwidth- or latency-intensive (e.g., by changing the configuration for a cell currently served by the open wireless access network 400 using the functional partitioning of option 7-2 to instead use the functional partitioning of option 2). This configuration change may be made if the performance of the open wireless access network 400 with the configuration change is expected to still meet the thresholds established for the other monitored performance attributes.

[0138] In another example, if the monitored processing load or performance of one or more unified remote units 404 does not meet the thresholds established for the current configuration of the open wireless access network 400, the functional partitioning used in one or more of the cells served by the open wireless access network 400 may be changed to use a functional partitioning that is less processing intensive (e.g., by changing the configuration for a cell currently served by the open wireless access network 400 using the functional partitioning of option 7-2 to instead use the functional partitioning of option 8). This configuration change may be made if the performance of the open wireless access network 400 with the configuration change is expected to still meet the thresholds established for other monitored performance attributes.

[0139] This configuration adaptation can be done automatically or manually.

[0140] 11 includes a high-level flowchart illustrating one exemplary embodiment of a method 1100 for optimizing forwarding of fronthaul data using functional partitioning and time-domain IQ data of Option 8. The embodiment of method 1100 is described herein as being implemented using the embodiment of open radio access network 400 described above in connection with FIGS. 4-7. More specifically, the processing associated with method 1100 may be implemented in one or more of base station node 500 (e.g., in IP stream transceiver 512 or 514) and unified remote unit 404 serving the associated cell. Other embodiments may be implemented in other manners.

[0141] 11 are generally arranged sequentially for ease of explanation, it should be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with method 1100 (and the blocks shown in FIG. 11) may occur in a different order (e.g., if at least some of the processing associated with the blocks is performed in parallel and / or in an event-driven manner). Also, while most standard exception handling has not been described for ease of explanation, it should be understood that method 1100 can, and typically does, include such exception handling.

[0142] Typically, when the functional split of Option 8 is used to communicate data over the fronthaul, fronthaul data for the entire channel bandwidth is transferred regardless of whether any of the corresponding physical radio blocks (PRBs) are unallocated. For example, this has historically been the case in digital DAS deployments. This issue may become more pronounced in 5G New Radio (NR) radio access networks that support the use of "bandwidth fractions." A bandwidth fraction is a contiguous set of physical resource blocks (PRBs) on a given carrier. By reducing the amount of bandwidth used to serve a UE, the amount of power used by the UE may be reduced. However, when the functional split of Option 8 is used in a 5G NR RAN, fronthaul data for the entire channel bandwidth is typically transferred regardless of whether bandwidth fractions are used.

[0143] Transferring fronthaul data for the entire channel bandwidth, regardless of whether any of the corresponding PRBs are unallocated, increases the amount of fronthaul bandwidth used. Emitting RF signals for unallocated PRBs may result in an increased noise level for those PRBs. This may also affect inter-cell interference coordination and the use of reserved regions on the channel bandwidth.

[0144] FIG. 11 illustrates one approach to addressing this issue when the functional split of Option 8 is used to transport fronthaul data over the fronthaul network.

[0145] The processing associated with method 1100 is aligned to transmission boundaries (ie, transmission time intervals (TTIs), slots, and symbols).

[0146] The method 1100 includes determining, for each TTI or slot, a received signal strength indicator (RSSI) value for a spectrum associated with each PRB of the channel bandwidth (block 1102). For the downlink, the IP stream transceiver 512 or 514 used in the BBU 503, 510, or 513 serving the associated cell may be configured to measure an RSSI value for the spectrum associated with each PRB of the channel bandwidth using time-domain IQ data generated for the entire channel bandwidth. Similarly, for the uplink, each unified remote unit 404 serving the associated cell may be configured to generate time-domain IQ data from a received analog uplink RF signal for the channel bandwidth and measure an RSSI value for the spectrum associated with each PRB of the channel bandwidth using the time-domain IQ data for the entire channel bandwidth.

[0147] In some embodiments, the time-domain IQ data is converted to frequency-domain IQ data by performing a fast Fourier transform (FFT), and the resulting frequency-domain IQ data is used to determine RSSI values ​​and to filter and forward the IQ data (described below). In such embodiments, the filtered IQ data may be forwarded over the fronthaul network as frequency-domain IQ data, in which case an inverse FFT (iFFT) operation is performed at the receiving end to generate time-domain IQ data for subsequent processing. In other embodiments, the time-domain IQ data is used to determine RSSI values ​​and to filter and forward the IQ data.

[0148] The method 1100 further includes, for each TTI or slot, determining whether each PRB of the channel bandwidth is allocated as a function of an associated RSSI value (block 1104). For example, the RSSI value for each PRB may be compared to a threshold selected such that the RSSI value is above the threshold if the corresponding PRB is allocated and below the threshold if the corresponding PRB is unallocated. Optionally, a correlation may be calculated between the corresponding time-domain IQ data for each PRB deemed unallocated and the expected demodulation reference symbol (DMRS) within the allocated PRB. If the correlation is sufficiently low (e.g., as determined using an associated correlation threshold), the PRB is deemed unallocated for the associated TTI or slot. Otherwise, the PRB is deemed allocated for the associated TTI or slot. This optional processing may be performed to improve the accuracy of this determination.

[0149] The method 1100 further includes bandpass filtering the IQ data to remove spectrum associated with unassigned PRBs and pass spectrum associated with assigned PRBs (block 1106). For example, the spectrum associated with the channel bandwidth may be subdivided into chunks of spectrum, each chunk including two PRBs (i.e., the number of chunks would be equal to half the total number of PRBs for the channel bandwidth). In such an example, the IQ data may be filtered to pass spectrum associated with each chunk including assigned PRBs and to remove any chunks that do not include assigned PRBs. Optionally, the passband for each consecutive set of assigned PRBs (i.e., for each BWP in the case of 5G NR) may be extended to include spectrum associated with additional PRBs to account for any Doppler effects.

[0150] The method 1100 further includes forwarding, via the fronthaul, a packet including the filtered IQ data and information identifying which portion of spectrum is being forwarded for the TTI or slot (block 1108). For example, the information identifying which portion of spectrum is being forwarded may take the form of a bitmap, with each bit position associated with each chunk of spectrum used for filtering. Each packet may include a portion of the filtered IQ data for the TTI or slot along with a header including the bitmap. A bit position in the bitmap is set for any chunk associated with filtered IQ data included in the associated packet.

[0151] In the downlink direction, the IP stream transceiver 512 or 514 serving the associated cell generates packets containing the filtered IQ data and a bitmap identifying which chunks are being transported and transmits them over the fronthaul to the various unified remote units 404 serving that cell. In the uplink direction, each unified remote unit 404 serving the associated cell generates packets containing the filtered IQ data and a bitmap identifying which chunks are being transported and transmits them over the fronthaul to the IP stream transceiver 512 or 514 serving that cell.

[0152] Method 1100 further includes receiving a packet transmitted for a TTI or slot (block 1110) and using filtered IQ data for the portion of the spectrum transmitted for the TTI or slot (block 1112). For example, in the downlink direction, each unified remote unit 404 receives a downlink packet transmitted from its respective IP stream transceiver 512 or 514, extracts filtered IQ data for the chunk of spectrum transmitted for the TTI or slot (indicated by a bitmap included in the packet's header), generates an RF signal from the extracted filtered IQ data for only the indicated chunk of spectrum, and amplifies and radiates the RF signal. Similarly, in the uplink direction, each IP stream transceiver 512 or 514 receives an uplink packet transmitted from each unified remote unit 404 serving its associated cell, extracts filtered IQ data for the chunk of spectrum transported for the TTI or slot (indicated by a bitmap included in the packet's header), and combines the corresponding IQ samples (e.g., by digitally summing them). If the IP stream transceiver 512 interfaces with the RRH 505 via an analog RF interface, the IP stream transceiver 512 generates an analog RF signal for the channel bandwidth and outputs the analog RF signal via the analog RF interface to the RRH 505. If the IP stream transceiver 514 interfaces directly with the BBU 510 or 513 via a digital baseband interface, the IP stream transceiver 514 generates time-domain IQ samples for the entire channel bandwidth in the format expected by the associated BBU 510 or 513 and outputs them to the BBU 510 or 513 via the digital baseband interface.

[0153] Transferring fronthaul data for only assigned PRBs reduces the amount of fronthaul bandwidth used. Also, only RF signals for assigned PRBs can be radiated, resulting in a reduced noise level for unassigned PRBs. This can also improve inter-cell interference coordination and utilization of reserved regions on the channel bandwidth.

[0154] The open radio access network described herein provides for the use of flexible unified remote units, each of which may simultaneously serve multiple cells using multiple wireless interface protocols, multiple generations of radio access technologies (e.g., 2G, 3G, 4G, and 5G), multiple frequency bands, and / or multiple functional divisions. This provides a flexible solution that can be adapted to changes in the number and / or type of services offered in a venue and / or a venue's switched Ethernet network.

[0155] Furthermore, the modular implementation of the unified remote unit described above allows a manufacturer or system integrator to easily assemble unified remote units that support different combinations of wireless interface protocols, frequency bands, and functional divisions. Such modular implementation also allows deployed unified remote units to be easily and flexibly upgraded in the field to support different wireless interface protocols, frequency bands, or functional divisions by changing or reconfiguring the software and / or radio boards used in the unified remote unit.

[0156] Several embodiments of the present invention have been described, as defined by the following claims. Nevertheless, it will be understood that modifications to the described embodiments can be made without departing from the spirit and scope of the claims. Accordingly, other embodiments are within the scope of the following claims.

[0157] Illustrative Embodiments Example 1 includes an open radio access network providing wireless coverage for multiple cells at a site, the open radio access network comprising: a virtualized headend including one or more base station nodes; and a plurality of unified remote units deployed at the site, each of the unified remote units associated with one or more antennas for wirelessly transmitting and receiving downlink and uplink radio frequency (RF) signals to and from user equipment, the plurality of unified remote units configured to communicate with the one or more base station nodes using a switched Ethernet network, and each unified remote unit including multiple downlink processing signal paths, multiple uplink processing signal paths, multiple downlink radio signal paths, and multiple uplink radio signal paths configured to support multiple fronthaul splits, multiple wireless interface protocols, multiple generations of radio access technologies, and multiple frequency bands.

[0158] Example 2 is a diagram illustrating a configuration of a virtualized headend configured to, for each of at least some cells served by the open radio access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band, the virtualized headend comprising one or more base station nodes serving the cell, wherein one or more unified remote units are used to serve the cell, the one or more base station nodes serving the cell being configured to: perform processing to generate respective digital downlink fronthaul data for the cell according to the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell; and transmit the respective digital downlink fronthaul data to one or more of the unified remote units serving the cell via a switched Ethernet network, wherein each of the one or more unified remote units serving the cell is connected to the switched Ethernet network. the unified remote unit is configured to: receive respective digital downlink fronthaul data for the cell from the unified remote unit network; perform processing on the respective digital downlink fronthaul data for the cell in accordance with a respective functional division, a respective wireless interface protocol, and a respective frequency band used for the cell to generate a respective downlink analog RF signal for the cell; and wirelessly transmit the respective downlink analog RF signal for the cell from an antenna used in association with the unified remote unit; wherein each of the one or more respective unified remote units used to serve the cell wirelessly receives a respective uplink analog RF signal for the cell via an antenna associated with the unified remote unit and performs processing on the respective uplink analog RF signal in accordance with a respective functional division, a respective wireless interface protocol, and a respective frequency band used for the cell;10. The open wireless access network of embodiment 1, wherein the open wireless access network is configured to generate respective digital uplink fronthaul data for the cell and transmit the respective digital uplink fronthaul data for the cell via a switched Ethernet network to one or more base station nodes used to serve the cell, wherein each of the one or more base station nodes serving the cell is configured to receive the respective digital uplink fronthaul data for the cell from the switched Ethernet network and perform processing of the respective digital uplink fronthaul data for the cell in accordance with a respective functional split, a respective wireless interface protocol, and a respective frequency band used for the cell.

[0159] Example 3 includes the open wireless access network of Example 1 or 2, wherein at least one of the unified remote units is configured to serve a first cell using a first functional division and to serve a second cell using a second functional division, and the first functional division is different from the second functional division.

[0160] Example 4 includes the open wireless access network of any of Examples 1-3, wherein at least one of the unified remote units is configured to serve a first cell using a first wireless interface protocol and to serve a second cell using a second wireless interface protocol, and the first wireless interface protocol is different from the second wireless interface protocol.

[0161] Example 5 includes the open wireless access network of any of Examples 1 to 4, wherein at least one of the unified remote units is configured to serve a first cell using a first frequency band and to serve a second cell using a second frequency band, and the first frequency band is different from the second frequency band.

[0162] Example 6 is a block diagram of a unified remote unit, each of which includes a plurality of downlink multi-protocol modules, each of which includes a plurality of downlink processing signal paths; a plurality of uplink multi-protocol modules, each of which includes a plurality of uplink processing signal paths; a plurality of downlink radio modules, each of which includes at least one of the downlink radio signal paths; and a plurality of uplink radio modules, each of which includes at least one of the uplink radio signal paths. The open wireless access network of any of Examples 1 to 5 includes a radio module, a downlink in-phase and quadrature (IQ) stream switch for coupling each downlink radio signal path to one or more respective downlink processing signal paths, an uplink in-phase and quadrature (IQ) stream switch for coupling each uplink radio signal path to one or more respective uplink radio signal paths, a control plane function for processing control plane communications, a management plane function for processing management plane communications, and a synchronization plane function for processing synchronization plane communications to synchronize its unified remote units to a master time reference for the open wireless access network.

[0163] Example 7 includes the open wireless access network of any of Examples 1-6, wherein one or more base station nodes used to serve at least one cell comprise: a baseband unit (BBU); a remote radio head (RRH) coupled to the BBU and configured to transmit downlink analog RF signals and receive uplink analog RF signals for the cell; and an Internet Protocol (IP) transceiver configured to: receive the downlink analog RF signals, digitize the downlink analog RF signals to generate downlink digital data, and generate IP packets for transmission over the switched Ethernet network to one or more respective unified remote units serving the cell; receive the IP packets transmitted over the switched Ethernet network from one or more respective unified remote units serving the cell, extract uplink digital data from the IP packets, convert the uplink digital data to uplink analog RF signals, and provide the uplink analog RF signals to the RRH.

[0164] Example 8 includes the open wireless access network of example 7, wherein the BBU and the RRH are configured to use at least one of a Common Public Radio Interface (CPRI), an enhanced Common Public Radio Interface (eCPRI), an open radio equipment interface (ORI), or an Open Base Station Standards Initiative (OBSAI) interface, which is a fronthaul interface.

[0165] Example 9 includes the open radio access network of any of Examples 1-8, wherein one or more base station nodes used to serve at least one cell comprises an Open Radio Access Network Alliance (O-RAN) distributed unit (DU) configured to perform at least some processing to generate respective digital downlink user plane and control plane fronthaul data for the cell and transmit the respective digital downlink user plane and control plane fronthaul data via a switched Ethernet network to one or more respective unified remote units serving the cell, receive the respective digital uplink user plane and control plane fronthaul data for the cell from the switched Ethernet network, and perform at least some of the processing of the respective digital uplink user plane and control plane fronthaul data for the cell.

[0166] Example 10 includes the open radio access network of example 9, wherein each of the one or more base station nodes used to serve the at least one cell further comprises an O-RAN central unit (CU).

[0167] Example 11 includes the open wireless access network of any of Examples 1-10, wherein one or more base station nodes used to serve at least one cell include: a baseband unit (BBU) that transmits downlink frames of digital downlink user plane and control plane data and receives digital uplink frames of uplink user plane and control plane data; and an Internet Protocol (IP) transceiver configured to receive the downlink frames, extract the digital downlink user plane and control plane data from the downlink frames, and encapsulate the digital downlink user plane and control plane data in IP packets for transmission over the switched Ethernet network to one or more respective unified remote units serving the cell; receive IP packets transmitted over the switched Ethernet network from one or more respective unified remote units serving the cell, extract the digital uplink user plane and control plane data from the IP packets, framing the digital uplink user plane and control plane data in uplink frames, and providing the uplink frames to the BBU.

[0168] Example 12 includes the open wireless access network of example 11, wherein the BBU is configured to use at least one of a Common Public Radio Interface (CPRI), an enhanced Common Public Radio Interface (eCPRI), an Open Radio Equipment Interface (ORI), or an Open Base Station Standards Initiative (OBSAI) interface, which is a fronthaul interface.

[0169] Example 13 includes the open wireless access network of any one of Examples 1 to 12, wherein at least one of the unified remote units is configured to operate as a single-node small cell base station for at least one cell served by the open wireless access network.

[0170] Example 14 includes the open wireless access network of any of Examples 1-13, wherein each unified remote unit is implemented in a modular manner using a central backplane to which various radio boards are coupled.

[0171] Example 15 includes the open wireless access network of any of Examples 1 to 14, wherein the open access wireless network is configured, for at least one cell served by the open access wireless network, to change the functional division used to serve the cell.

[0172] Example 16 includes the open wireless access network of example 15, in which the functional division is changed manually or automatically.

[0173] Example 17 includes the open wireless access network of any of Examples 1-16, wherein the open access wireless network is configured to monitor at least one performance attribute associated with the open access wireless network and adapt a configuration of the open access wireless network based on the monitored performance attribute.

[0174] Example 18 includes the open wireless access network of any of Examples 1 to 17, wherein when at least one base station node is configured to use fronthaul splitting to communicate time-domain IQ samples, at least some of the time-domain IQ samples are configured to be filtered to remove IQ data for unassigned physical resource blocks and pass IQ data for assigned physical resource blocks.

[0175] Example 19 includes a unified remote unit for use in an open wireless access network to provide wireless coverage for multiple cells at a site, the open wireless access network comprising a virtualized headend including one or more base station nodes, the unified remote unit comprising multiple downlink processing signal paths, multiple uplink processing signal paths, multiple downlink wireless signal paths, and multiple uplink wireless signal paths, the unified remote unit configured to communicate with the one or more base station nodes using a switched Ethernet network, the multiple downlink processing signal paths, the multiple uplink processing signal paths, the multiple downlink wireless signal paths, and the multiple uplink wireless signal paths supporting multiple fronthaul splits for communicating user plane and control plane transport data to and from the base station nodes, and configured to support multiple wireless interface protocols, multiple generations of radio access technologies, and frequency bands for communicating wirelessly with user equipment.

[0176] Example 20 includes, for each of at least some cells served by the open wireless access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band, a unified remote unit receiving, from the switched Ethernet network, respective digital downlink fronthaul data for that cell transmitted from one or more respective base station nodes serving that cell, and performing processing on the respective digital downlink fronthaul data for that cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for that cell to generate a respective downlink analog RF signal for that cell; and transmitting, via a switched Ethernet network, the respective digital uplink fronthaul data for the cell to one or more base station nodes used to serve the cell.

[0177] Example 21 includes the unified remote unit of example 19 or 20, wherein the unified remote unit is configured to serve a first cell using a first functional division and to serve a second cell using a second functional division, and the first functional division is different from the second functional division.

[0178] Example 22 includes the unified remote unit of any of Examples 19-21, wherein the unified remote unit is configured to serve a first cell using a first wireless interface protocol and to serve a second cell using a second wireless interface protocol, and the first wireless interface protocol is different from the second wireless interface protocol.

[0179] Example 23 includes the unified remote unit of any of Examples 19-22, wherein the unified remote unit is configured to serve a first cell using a first frequency band and to serve a second cell using a second frequency band, and the first frequency band is different from the second frequency band.

[0180] Example 24 is a diagram illustrating a unified remote unit including a plurality of downlink multi-protocol modules, each of which includes a plurality of downlink processing signal paths; a plurality of uplink multi-protocol modules, each of which includes a plurality of uplink processing signal paths; a plurality of downlink radio modules, each of which includes at least one of the downlink radio signal paths; and a plurality of uplink radio modules, each of which includes at least one of the uplink radio signal paths. a downlink in-phase and quadrature (IQ) stream switch for coupling each downlink radio signal path to a respective one or more downlink processing signal paths; an uplink in-phase and quadrature (IQ) stream switch for coupling each uplink radio signal path to a respective one or more uplink radio signal paths; a control plane function for processing control plane communications; a management plane function for processing management plane communications; and a synchronization plane function for processing synchronization plane communications to synchronize the unified remote unit to a master time reference for the open wireless access network.

[0181] Example 25 includes the unified remote units of any of Examples 19-24, wherein at least one of the unified remote units is configured to operate as a single-node small cell base station for at least one cell served by the open wireless access network.

[0182] Example 26 includes the unified remote unit of any of Examples 19-25, wherein the unified remote unit is implemented in a modular manner using a central backplane to which various radio boards are coupled.

[0183] Example 27 includes the unified remote unit of any of Examples 19-26, wherein the unified remote unit is configured, when at least one base station node is configured to use fronthaul splitting to communicate time domain IQ samples, to filter at least some of the time domain IQ samples to remove IQ data for unassigned physical resource blocks and pass IQ data for assigned physical resource blocks.

[0184] Example 28 is a method of providing wireless coverage for a plurality of cells at a site using an open wireless access network, the open wireless access network comprising a virtualized headend including one or more base station nodes and a plurality of unified remote units deployed at the site, each of the plurality of unified remote units being associated with one or more antennas for wirelessly transmitting and receiving downlink and uplink radio frequency (RF) signals to and from user equipment, the method comprising, for each of at least some cells served by the open wireless access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band, performing processing by each one or more base station nodes serving that cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for that cell to generate respective digital downlink fronthaul data for that cell; transmitting, via a switched Ethernet network, respective digital downlink fronthaul data to one or more respective unified remote units serving the cell; receiving, by each of the one or more respective unified remote units serving the cell, respective digital downlink fronthaul data for the cell from the switched Ethernet network; processing, in accordance with a respective functional division, a respective wireless interface protocol, and a respective frequency band used for the cell, the respective digital downlink fronthaul data for the cell to generate a respective downlink analog RF signal for the cell; wirelessly transmitting, from an antenna associated with the unified remote unit, the respective downlink analog RF signal for the cell; and transmitting, by each of the one or more respective unified remote units used to serve the cell, a respective uplink analog RF signal for the cell.wirelessly receiving via an antenna associated with the unified remote unit, and performing processing of each uplink analog RF signal in accordance with a respective functional partition, a respective wireless interface protocol, and a respective frequency band used for the cell to generate respective digital uplink fronthaul data for the cell; transmitting each digital uplink fronthaul data for the cell over a switched Ethernet network to one or more base station nodes used to serve the cell; receiving, by each of the one or more base station nodes serving the cell, from the switched Ethernet network, each digital uplink fronthaul data for the cell; and performing processing of each digital uplink fronthaul data for the cell in accordance with the respective functional partition, a respective wireless interface protocol, and a respective frequency band used for the cell.

[0185] Example 29 includes the method of example 28, wherein at least one of the unified remote units is configured to operate as a single-node small cell base station for at least one cell served by the open wireless access network.

[0186] Example 30 includes the method of example 28 or 29, wherein at least one of the unified remote units is configured to serve a first cell using a first functional division and to serve a second cell using a second functional division, and the first functional division is different from the second functional division.

[0187] Example 31 includes the method of any of Examples 28-30, wherein at least one of the unified remote units is configured to serve a first cell using a first wireless interface protocol and to serve a second cell using a second wireless interface protocol, and the first wireless interface protocol is different from the second wireless interface protocol.

[0188] Example 32 includes the method of any of Examples 28-31, wherein at least one of the unified remote units is configured to serve a first cell using a first frequency band and to serve a second cell using a second frequency band, and the first frequency band is different from the second frequency band.

[0189] Example 33 includes the method of any of Examples 28 to 32, wherein the open access wireless network is configured, for at least one cell served by the open access wireless network, to change the functional division used to serve the cell.

[0190] Example 34 includes the method of example 33, wherein the functional division is changed manually or automatically.

[0191] Example 35 includes the method of any of Examples 28-34, further including monitoring at least one performance attribute associated with the open access wireless network and adapting a configuration of the open access wireless network based on the monitored performance attribute.

[0192] Example 36 includes the method of any of Examples 28 to 35, wherein when at least one base station node is configured to use fronthaul splitting to communicate time-domain IQ samples, at least some of the time-domain IQ samples are configured to be filtered to remove IQ data for unassigned physical resource blocks and pass IQ data for assigned physical resource blocks.

Claims

1. 1. An open radio access network that provides wireless coverage for a plurality of cells at a site, the open radio access network comprising: a virtualized headend including one or more base station nodes; a plurality of unified remote units deployed at the site, each unified remote unit associated with one or more antennas for wirelessly transmitting and receiving downlink and uplink radio frequency (RF) signals to and from user equipment; the plurality of unified remote units are configured to communicate with the one or more base station nodes using a switched Ethernet network; An open wireless access network including multiple downlink processing signal paths, multiple uplink processing signal paths, multiple downlink radio signal paths, and multiple uplink radio signal paths, each unified remote unit configured to support multiple fronthaul splits, multiple wireless interface protocols, multiple generations of radio access technologies, and multiple frequency bands.

2. for each of at least some cells served by the open radio access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band; the virtualized headend comprising one or more base station nodes each serving its cell; each of the one or more unified remote units used to serve the cell; each of said one or more base station nodes serving the cell; performing processing to generate respective digital downlink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell; and transmitting the respective digital downlink fronthaul data via the switched Ethernet network to the respective one or more of the unified remote units serving that cell; each of said respective one or more unified remote units serving the cell; receiving the respective digital downlink fronthaul data for the cell from the switched Ethernet network; performing processing of the respective digital downlink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell to generate a respective downlink analog RF signal for the cell; and wirelessly transmitting the respective downlink analog RF signal for the cell from the antenna used in association with the unified remote unit; each of said respective one or more unified remote units used to serve that cell; wirelessly receiving a respective uplink analog RF signal for the cell via the antenna associated with the unified remote unit; performing processing of the respective uplink analog RF signals in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell to generate respective digital uplink fronthaul data for the cell; and transmitting the respective digital uplink fronthaul data for the cell via the switched Ethernet network to the one or more base station nodes used to serve the cell; each of said one or more base station nodes serving the cell; receiving the respective digital uplink fronthaul data for the cell from the switched Ethernet network; and performing processing of the respective digital uplink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell.

3. At least one of the unified remote units: Serving a first cell using a first functional division; and servicing a second cell using a second functional division; The open wireless access network of claim 1 , wherein the first functional division is different from the second functional division.

4. At least one of the unified remote units: Serving a first cell using a first wireless interface protocol; and serving the second cell using a second wireless interface protocol; The open wireless access network of claim 1 , wherein the first wireless interface protocol is different from the second wireless interface protocol.

5. At least one of the unified remote units: Serving a first cell using a first frequency band; and serving a second cell using a second frequency band; The open wireless access network of claim 1 , wherein the first frequency band is different from the second frequency band.

6. each of said unified remote units: a plurality of downlink multi-protocol modules, each of which includes a plurality of said downlink processing signal paths; a plurality of uplink multi-protocol modules, each of which includes a plurality of said uplink processing signal paths; a plurality of downlink radio modules, each of which includes at least one of the downlink radio signal paths; a plurality of uplink radio modules, each of which includes at least one of the uplink radio signal paths; a downlink in-phase and quadrature (IQ) stream switch for coupling each downlink radio signal path to a respective one or more downlink processing signal paths; an uplink in-phase and quadrature (IQ) stream switch for coupling each uplink radio signal path to a respective one or more uplink radio signal paths; a control plane function for handling control plane communications; a management plane function for handling management plane communications; a synchronization plane function for processing synchronization plane communications to synchronize its unified remote units to a master time reference for the open wireless access network.

7. One or more base station nodes used to serve at least one cell, a baseband unit (BBU); a remote radio head (RRH) coupled to the BBU and configured to transmit downlink analog RF signals and receive uplink analog RF signals for the cell; 1. An Internet Protocol (IP) transceiver comprising: receiving the downlink analog RF signal, digitizing the downlink analog RF signal to generate downlink digital data, and generating IP packets for transmission over the switched Ethernet network to the respective one or more of the unified remote units serving the cell; and an IP transceiver configured to receive IP packets transmitted over the switched Ethernet network from the respective one or more of the unified remote units serving its cell, extract uplink digital data from the IP packets, convert the uplink digital data to the uplink analog RF signal, and provide the uplink analog RF signal to the remote radio head.

8. 8. The open radio access network of claim 7, wherein the BBU and the RRH are configured to use at least one of a Common Public Radio Interface (CPRI), an enhanced Common Public Radio Interface (eCPRI), an Open Radio Equipment Interface (ORI), or an Open Base Station Standards Initiative (OBSAI) interface, which is a fronthaul interface.

9. One or more base station nodes used to serve at least one cell, An Open Radio Access Network Alliance (O-RAN) Distributed Unit (DU), comprising: performing at least some processing to generate respective digital downlink user plane and control plane fronthaul data for the cell and transmitting the respective digital downlink user plane and control plane fronthaul data via the switched Ethernet network to the respective one or more of the unified remote units serving the cell; and performing at least some of the processing of the respective digital uplink user plane and control plane fronthaul data for the cell from the switched Ethernet network.

10. The open radio access network of claim 9 , wherein each of the one or more base station nodes used to serve at least one cell further comprises an O-RAN central unit (CU).

11. One or more base station nodes used to serve at least one cell, a baseband unit (BBU) for transmitting downlink frames of digital downlink user plane and control plane data and receiving frames of digital uplink frames of uplink user plane and control plane data; 1. An Internet Protocol (IP) transceiver comprising: receiving the downlink frames, extracting the digital downlink user plane and control plane data from the downlink frames, and encapsulating the digital downlink user plane and control plane data in IP packets for transmission over the switched Ethernet network to the respective one or more of the unified remote units serving the cell; and an IP transceiver configured to receive IP packets transmitted over the switched Ethernet network from the respective one or more of the unified remote units serving its cell, extract the digital uplink user plane and control plane data from the IP packets, frame the digital uplink user plane and control plane data into the uplink frames, and provide the uplink frames to the BBU.

12. 12. The open radio access network of claim 11, wherein the BBU is configured to use at least one of the following fronthaul interfaces: a Common Public Radio Interface (CPRI), an enhanced Common Public Radio Interface (eCPRI), an Open Radio Equipment Interface (ORI), or an Open Base Station Standards Initiative (OBSAI) interface.

13. 10. The open wireless access network of claim 1, wherein for at least one cell served by the open wireless access network, at least one of the unified remote units is configured to operate as a single-node small cell base station.

14. 10. The open wireless access network of claim 1, wherein each unified remote unit is implemented in a modular fashion using a central backplane to which various radio boards are coupled.

15. 2. The open wireless access network of claim 1, wherein the open access wireless network is configured to, for at least one cell served by the open access wireless network, change the functional division used to serve that cell.

16. The open radio access network of claim 15, wherein the functional division is changed manually or automatically.

17. the open access wireless network, monitoring at least one performance attribute associated with the open access wireless network; and adapting the configuration of the open access wireless network based on the monitored performance attributes.

18. 2. The open wireless access network of claim 1, wherein the open access wireless network is configured such that when at least one base station node is configured to use fronthaul splitting to communicate time domain IQ samples, at least some of the time domain IQ samples are filtered to remove IQ data for unassigned physical resource blocks and pass IQ data for assigned physical resource blocks.

19. 1. A unified remote unit for use in an open radio access network to provide wireless coverage for multiple cells at a site, the open radio access network comprising a virtualized headend including one or more base station nodes, the unified remote unit comprising: a plurality of downlink processing signal paths; a plurality of uplink processing signal paths; a plurality of downlink wireless signal paths; a plurality of uplink wireless signal paths; the unified remote unit is configured to communicate with the one or more base station nodes using a switched Ethernet network; a unified remote unit configured to support multiple fronthaul splits for communicating user plane and control plane transport data to and from a base station node, and to support multiple wireless interface protocols, multiple generations of radio access technologies, and frequency bands for communicating wirelessly with the user equipment, wherein the multiple downlink processing signal paths, the multiple uplink processing signal paths, the multiple downlink radio signal paths, and the multiple uplink radio signal paths support multiple fronthaul splits for communicating user plane and control plane transport data to and from a base station node, and to support multiple wireless interface protocols, multiple generations of radio access technologies, and frequency bands for communicating wirelessly with the user equipment.

20. for each of at least some cells served by the open radio access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band, the unified remote unit: receiving, from the switched Ethernet network, respective digital downlink fronthaul data for the cell transmitted from each one or more base station nodes serving the cell; performing processing of the respective digital downlink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell to generate a respective downlink analog RF signal for the cell; wirelessly transmitting the respective downlink analog RF signal for that cell from an antenna associated with that unified remote unit; wirelessly receiving a respective uplink analog RF signal for the cell via the antenna associated with the unified remote unit; performing processing of the respective uplink analog RF signals in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell to generate respective digital uplink fronthaul data for the cell; and transmitting the respective digital uplink fronthaul data for that cell via the switched Ethernet network to the one or more base station nodes used to serve that cell.

21. the unified remote unit: Serving a first cell using a first functional division; and servicing a second cell using a second functional division; 20. The unified remote unit of claim 19, wherein the first functional division is different from the second functional division.

22. the unified remote unit: Serving a first cell using a first wireless interface protocol; and serving the second cell using a second wireless interface protocol; 20. The unified remote unit of claim 19, wherein the first wireless interface protocol is different from the second wireless interface protocol.

23. the unified remote unit: Serving a first cell using a first frequency band; and serving a second cell using a second frequency band; 20. The unified remote unit of claim 19, wherein the first frequency band is different from the second frequency band.

24. the unified remote unit: a plurality of downlink multi-protocol modules, each of which includes a plurality of said downlink processing signal paths; a plurality of uplink multi-protocol modules, each of which includes a plurality of said uplink processing signal paths; a plurality of downlink radio modules, each of which includes at least one of the downlink radio signal paths; a plurality of uplink radio modules, each of which includes at least one of the uplink radio signal paths; a downlink in-phase and quadrature (IQ) stream switch for coupling each downlink radio signal path to a respective one or more downlink processing signal paths; an uplink in-phase and quadrature (IQ) stream switch for coupling each uplink radio signal path to a respective one or more uplink radio signal paths; a control plane function for handling control plane communications; a management plane function for handling management plane communications; 20. The unified remote unit of claim 19, comprising: a synchronization plane function for processing synchronization plane communications to synchronize the unified remote unit to a master time reference for the open wireless access network.

25. 20. The unified remote unit of claim 19, wherein for at least one cell served by the open wireless access network, at least one of the unified remote units is configured to operate as a single-node small cell base station.

26. 20. The unified remote unit of claim 19, wherein the unified remote unit is implemented in a modular manner using a central backplane to which various radio boards are coupled.

27. 20. The unified remote unit of claim 19, wherein the unified remote unit is configured such that when at least one base station node is configured to use fronthaul splitting to communicate time domain IQ samples, at least some of the time domain IQ samples are filtered to remove IQ data for unassigned physical resource blocks and pass IQ data for assigned physical resource blocks.

28. A method of providing wireless coverage for a plurality of cells at a site using an open radio access network, said open radio access network comprising a virtualized headend including one or more base station nodes and a plurality of unified remote units deployed at said site, each of said plurality of unified remote units being associated with one or more antennas for wirelessly transmitting and receiving downlink and uplink radio frequency (RF) signals to and from user equipment, said method comprising: for each of at least some cells served by said open radio access network using a respective functional division, a respective wireless interface protocol, and a respective frequency band; by each one or more base station nodes serving that cell; performing processing to generate respective digital downlink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell; transmitting the respective digital downlink fronthaul data via the switched Ethernet network to the respective one or more of the unified remote units serving that cell; by each of the one or more respective unified remote units serving the cell; receiving the respective digital downlink fronthaul data for the cell from the switched Ethernet network; performing processing of the respective digital downlink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell to generate a respective downlink analog RF signal for the cell; wirelessly transmitting the respective downlink analog RF signal for that cell from an antenna associated with that unified remote unit; by each of said respective one or more unified remote units used to serve that cell; wirelessly receiving a respective uplink analog RF signal for the cell via the antenna associated with the unified remote unit; performing processing of the respective uplink analog RF signals in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell to generate respective digital uplink fronthaul data for the cell; transmitting the respective digital uplink fronthaul data for that cell via the switched Ethernet network to the one or more base station nodes used to serve that cell; by said respective one or more base station nodes serving that cell; receiving the respective digital uplink fronthaul data for the cell from the switched Ethernet network; performing processing of the respective digital uplink fronthaul data for the cell in accordance with the respective functional division, the respective wireless interface protocol, and the respective frequency band used for the cell; At least one of the unified remote units: Serving a first cell using a first functional division; and servicing a second cell using a second functional division; The method, wherein the first functional division is different from the second functional division.

29. 30. The method of claim 28, wherein at least one of the unified remote units is configured to operate as a single-node small cell base station for at least one cell served by the open radio access network.

30. At least one of the unified remote units: Serving a first cell using a first wireless interface protocol; and serving the second cell using a second wireless interface protocol; 30. The method of claim 28, wherein the first wireless interface protocol is different from the second wireless interface protocol.

31. At least one of the unified remote units: Serving a first cell using a first frequency band; and serving a second cell using a second frequency band; 30. The method of claim 28, wherein the first frequency band is different from the second frequency band.

32. 29. The method of claim 28, wherein the open access wireless network is configured to, for at least one cell served by the open access wireless network, change the functional division used to serve that cell.

33. The method of claim 32 , wherein the functional division is changed manually or automatically.

34. monitoring at least one performance attribute associated with the open access wireless network; 30. The method of claim 28, further comprising: adapting the configuration of the open access wireless network based on the monitored performance attributes.

35. 29. The method of claim 28, wherein when at least one base station node is configured to use fronthaul splitting to communicate time domain IQ samples, at least some of the time domain IQ samples are configured to be filtered to remove IQ data for unassigned physical resource blocks and to pass IQ data for assigned physical resource blocks.

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