WO2025174702A1

WO2025174702A1 - Massive-mimo realization with distributed antenna system (das)

Info

Publication number: WO2025174702A1
Application number: PCT/US2025/015283
Authority: WO
Inventors: Suresh N. SRIRAM
Original assignee: Outdoor Wireless Networks LLC
Current assignee: Outdoor Wireless Networks LLC
Priority date: 2024-02-13
Filing date: 2025-02-10
Publication date: 2025-08-21
Anticipated expiration: 2026-08-13

Abstract

The present disclosure is directed to a Distributed Antenna System (DAS) comprising a master unit (MU) and a plurality of access points (APs) communicatively coupled with the MU and configured to wirelessly communicate with a plurality of UEs via a respective set of antennas. The MU is configured to receive a plurality of capability information messages from the plurality of APs, each message comprising information indicating a number of antennas associated with a corresponding AP; generate at least one group of APs from the plurality of APs by processing the plurality of messages; generate at least one combined capability information message corresponding to the at least one group of APs, each combined message comprising information indicating a number of antennas associated with a corresponding group of APs; and transmit the at least one combined message to a donor base station (BS) for configuring Massive MIMO operations of the donor BS.

Description

MASSIVE-MIMO REALIZATION WITH DISTRIBUTED ANTENNA SYSTEM

(DAS)

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States Provisional Patent Application Serial No. 63/552,870, filed on February 13, 2024, and entitled “MASSIVE-MIMO REALIZATION WITH DISTRIBUTED ANTENNA SYSTEM (DAS)”, which is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure in general relates to distributed antenna systems. More particularly, but not exclusively, the present disclosure relates to methods and apparatuses for Massive-MIMO (M-MIMO) realization with the distributed antenna systems.

BACKGROUND

[0003] A distributed antenna system (DAS) typically includes one or more central units or nodes (also referred to here as “central access nodes (CANs)” or “master units”) that are communicatively coupled to a plurality of remotely located access points (APs) or antenna units (also referred to here as “remote antenna units” or “radio units” (RUs)), where each access point can be coupled directly to one or more of the central access nodes or indirectly via one or more other remote units and/or via one or more intermediary or expansion units or nodes (also referred to here as “transport expansion nodes (TENs)”). A DAS is typically used to improve the coverage provided by one or more base stations that are coupled to the central access nodes. These base stations can be coupled to the one or more central access nodes via one or more cables or via a wireless connection, for example, using one or more donor antennas. The wireless service provided by the base stations can include commercial cellular service and/or private or public safety wireless communications.

[0004] In general, each central access node receives one or more downlink signals from one or more base stations and generates one or more downlink transport signals derived from one or more of the received downlink base station signals. Each central access node transmits one or more dow nlink transport signals to one or more of the access points. Each access point receives the downlink transport signals transmitted to it from one or more central access nodes and uses the received downlink transport signals to generate one or more downlink radio frequency signals that are radiated from one or more coverage antennas associated with that access point. The downlink radio frequency signals are radiated for reception by user equipment. Typically, the downlink radio frequency signals associated with each base station are simulcasted from multiple remote units. In this way, the DAS increases the coverage area for the downlink capacity provided by the base stations.

[0005] Likewise, each access point receives one or more uplink radio frequency signals transmitted from the user equipment. Each access point generates one or more uplink transport signals derived from the one or more uplink radio frequency signals and transmits them to one or more of the central access nodes. Each central access node receives the respective uplink transport signals transmitted to it from one or more access points and uses the received uplink transport signals to generate one or more uplink base station radio frequency signals that are provided to the one or more base stations associated with that central access node. Typically, this involves, among other things, combining or summing uplink signals received from multiple access points in order to produce the base station signal provided to each base station. In this way, the DAS increases the coverage area for the uplink capacity provided by the base stations.

[0006] A DAS can use either digital transport, analog transport, or combinations of digital and analog transport for generating and communicating the transport signals between the central access nodes, the access points, and any transport expansion nodes.

[0007] Typically, a DAS is operated in a “simulcast” mode in which downlink signals for each base station are transmitted from multiple access points of the DAS and in which uplink signals for each base station are generated by combining signals from multiple access points.

[0008] To improve wireless communications, such as communications from a base station to mobile devices, Multiple-Input/Multiple-Output (“MIMO”) technology might be utilized to provide advanced solutions for performance enhancement and broadband wireless communication systems. Massive MIMO (M-MIMO) is an extension of traditional MIMO technology that involves using a very large number of antennas compared to the MIMO technology⁷. However, the Massive MIMO systems available today have certain limitations e.g., in terms of number of antennas, antenna spacings, complex processing at Access Points and Distributed Units, lack of dynamically adaptability and multi-operator support, and the like. Thus, there is a need for further improvements in the technology and utilize the capabilities of the DAS to overcome the limitations of existing Massive MIMO systems.

[0009] The information disclosed in this background section is only for enhancement of understanding of the general background of the disclosure and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY

[0010] Embodiments of the present disclosure provide a distributed antenna system that is configured to operate in a Massive MIMO mode of operation.

[0011] One embodiment is directed to a Distributed Antenna System (DAS) comprising a master unit (MU) communicatively coupled with a donor base station (BS), and a plurality of access points (APs) communicatively coupled with the MU and configured to wirelessly communicate with a plurality of user equipment (UEs) via a respective set of one or more coverage antennas. The MU is configured to receive a plurality of capability information messages from the plurality of APs, where each capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding RU. The MU is further configured to generate at least one group of APs from the plurality of APs by processing the plurality of capability information messages and generate at least one combined capability information message corresponding to the at least one group of APs, where each combined capability' information message comprises information indicating at least a number of coverage antennas associated with a corresponding group of APs. The MU is further configured to transmit the at least one combined capability information message to the donor BS for configuring Massive Multiple-Input-Multiple-Output (M-MIMO) operations of the donor BS.

[0012] Another embodiment is directed to a method of providing wireless communication using a DAS that comprises a MU communicatively coupled with a donor base station, and a plurality of APs communicatively coupled with the MU and configured to wirelessly communicate with a plurality' of UEs via a respective set of one or more coverage antennas. The method comprises receiving a plurality of capability information messages from the plurality of APs, where each capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding RU. The method further comprises generating at least one group of APs from the plurality of APs by processing the plurality of capability information messages and generating at least one combined capability information message corresponding to the at least one group of APs, wherein each combined capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding group of APs. The method further comprises transmitting the at least one combined capability information message to the donor BS for configuring M-MIMO operations of the donor BS.

[0013] The foregoing summary⁷ is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF DRAWINGS

[0014] Further aspects and advantages of the present disclosure will be readily understood from the following detailed description with reference to the accompanying drawings. Reference numerals have been used to refer to identical or functionally similar elements. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure wherein:

[0015] FIGS. 1A-1C are block diagrams illustrating one exemplary embodiment of a virtualized DAS (vDAS) 100, in accordance with some embodiments of the present disclosure.

[0016] FIG. 2 is a block diagram illustrating one exemplary embodiment of an apparatus 200 that can be used in the vDAS, in accordance with some embodiments of the present disclosure.

[0017] FIG. 3 comprises a high-level flowchart illustrating one exemplary embodiment of a method 300 of providing wireless communication, in accordance with some embodiments of the present disclosure.

[0018] FIGS. 4A-4D are block diagrams illustrating one exemplary⁷ embodiment of vDAS

400 in which at least some of the APs are coupled to one or more vMU serving them via one or more intermediate combining nodes (ICNs), in accordance with some embodiments of the present disclosure.

[0019] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of the illustrative systems embodying the principles of the present disclosure. Similarly, it will be appreciated that any flowcharts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION

[0020] In the present document, the word “exemplary'’ is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or implementation of the present disclosure described herein as “exemplary ” is not necessarily to be construed as preferred or advantageous over other embodiments. While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular form disclosed, but on the contrary , the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the disclosure.

[0021] The terms “comprise(s)”. “comprising”, “include(s)”, or any other vanations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device, apparatus, system, or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or apparatus or system or method. In other words, one or more elements in a device or system or apparatus preceded by “comprises. . . a” does not, without more constraints, preclude the existence of other elements or additional elements in the system.

[0022] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration of specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense. In the following description, well know n functions or constructions are not described in detail since they would obscure the description with unnecessary detail.

[0023] FIGS. 1A-1C are block diagrams illustrating one exemplary embodiment of a virtualized DAS (vDAS) 100. In the exemplary embodiment of the virtualized DAS 100 shown in FIGS. 1A-1C, one or more nodes or functions of a traditional DAS (such as a master unit or CAN) are implemented using one or more virtual network functions (VNFs) 102 executing on one or more physical server computers (also referred to here as ‘‘physical servers'’ or just “servers’") 104 (for example, one or more commercial-off-the-shelf (COTS) servers of the type that are deployed in data centers or “clouds” maintained by enterprises, communication service providers, or cloud services providers).

[0024] Each such physical server computer 104 is configured to execute software that is configured to implement the various functions and features described here as being implemented by the associated VNF 102. Each such physical server computer 104 comprises one or more programmable processors for executing such software. The software comprises program instructions that are stored (or otherwise embodied) on or in an appropriate non-transitory storage medium or media (such as flash or other non-volatile memory, magnetic disc drives, and/or optical disc drives) from which at least a portion of the program instructions are read by the respective programmable processor for execution thereby. Both local storage media and remote storage media (for example, storage media that is accessible over a network), as well as removable media, can be used. Each such physical server computer 104 also includes memory for storing the program instructions (and any related data) dunng execution by the respective programmable processor.

[0025] In the example shown in FIGS. 1A-1C, virtualization software 106 is executed on each physical server computer 104 in order to provide a virtualized environment 108 in which one or more one or more virtual entities 110 (such as one or more virtual machines and/or containers) are used to deploy and execute the one or more VNFs 102 of the vDAS 100. In the following description, it should be understood that references to “virtualization” are intended to refer to, and include within their scope, any type of virtualization technology, including “container” based virtualization technology (such as, but not limited to, Kubemetes). [0026] In the example shown in FIGS. 1A-1C, the vDAS 100 comprises at least one virtualized master unit (vMU) 112 and a plurality of access points (APs) (also referred here to as “remote antenna units” (RAUs) or “radio units” (RUs)) 114. Each vMU 112 is configured to implement at least some of the functions normally carried out by a physical master unit (MU) or CAN in a traditional DAS.

[0027] Each of the vMU 112 is implemented as a respective VNF 102 deployed on one or more of the physical servers 104. Each of the APs 114 is implemented as a physical network function (PNF) and is deployed in or near a physical location where coverage is to be provided.

[0028] Each of the APs 114 includes, or is otherwise coupled to, one or more coverage antennas 116 via which downlink radio frequency (RF) signals are radiated for reception by user equipment (UEs) 118 and via w hich uplink RF signals transmitted from UEs 118 are received. Each of the APs 114 is communicatively coupled to the respective one or more vMU 112 (and the physical server computers 104 on which the vMUs 112 are deployed) using a fronthaul network 120. The fronthaul network 120 used for transport between each vMU 112 and the APs 114 can be implemented in various ways. Various examples of how^r the fronthaul network 120 can be implemented are illustrated in FIGS.

1A-1C

[0029] In the example shown in FIG. 1A, the fronthaul network 120 is implemented using a switched Ethernet network 122 that is used to communicatively couple each AP 114 to each vMU 112 serving that AP 114. That is, in contrast to a traditional DAS in which each AP 114 is coupled to each CAN serving it using only point-to-point links, in the vDAS 100 shown in FIG. 1 A, each AP 114 is coupled to each vMU 112 serving it using at least some shared communication links.

[0030] In the example shown in FIG. IB, the fronthaul network 120 is implemented using only point-to-point Ethernet links 123, where each AP 114 is coupled to each serving vMU 112 serving it via a respective one or more point-to-point Ethernet links 123.

[0031] In the example shown in FIG. 1C, the fronthaul network 120 is implemented using a combination of a switched Ethernet network 122 and point-to-point Ethernet links 123, where at least one AP 114 is coupled to a vMU 112 serving it at least in part using the switched Ethernet network 122 and at least one AP 114 is coupled to a vMU 112 serving it at least in part using at least one point-to-point Ethernet link 123. FIGS. 4A-4D are block diagrams illustrating other examples in which one or more intermediate combining nodes (ICNs) 402 are used. The examples shown in FIGS. 4A-4D are described below. It is to be understood, however, that FIGS. 1A-1C and 4A-4D illustrate only a few examples of how the fronthaul network (and the vDAS more generally) can be implemented and that other variations are possible.

[0032] The vDAS 100 is configured to be coupled to one or more base stations 124 (also referred to as “donor base stations” (DBS or Donor BS)) in order to improve the coverage provided by the base stations 124. That is, each base station 124 is configured to provide wireless capacity, whereas the vDAS 100 is configured to provide improved wireless coverage for the wireless capacity provided by the base station 124. As used here, unless otherwise explicitly indicated, references to “base station” include both (1) a “complete” base station that interfaces with the vDAS 100 using the analog radio frequency (RF) interface that would otherwise be used to couple the complete base station to a set of antennas as well as (2) a first portion of a base station 124 (such as a baseband unit (BBU), distributed unit (DU), or similar base station entity) that interfaces with the vDAS 100 using a digital fronthaul interface that would otherwise be used to couple that first portion of the base station to a second portion of the base station (such as a remote radio head (RRH), radio unit (RU). or similar radio entity). In the latter case, different digital fronthaul interfaces can be used (including, for example, a Common Public Radio Interface (CPRI) interface, an evolved CPRI (eCPRI) interface, an IEEE 1914.3 Radio-over-Ethemet (RoE) interface, a functional application programming interface (FAPI) interface, a network FAPI (nF API) interface), or an 0-RAN fronthaul interface) and different functional splits can be supported (including, for example, functional split 8. functional split 7-2, and functional split 6). The O-RAN Alliance publishes various specifications for implementing RANs in an open manner. (“0-RAN" is an acronym that also stands for “Open RAN,” but in this description references to “O-RAN” should be understood to be referring to the 0-RAN Alliance and/or entities or interfaces implemented in accordance with one or more specifications published by the O-RAN Alliance.)

[0033] Each base station 124 coupled to the vDAS 100 can be co-located with the vMU 112 to which it is coupled. A co-located base station 124 can be coupled to the vMU 112 to which it is coupled using one or more point-to-point links (for example, where the colocated base station 124 comprises a 4G LTE BBU supporting a CPRI fronthaul interface. the 4G LTE BBU can be coupled to the vMU 112 using one or more optical fibers that directly connect the BBU to the vMU 112) or a shared network (for example, where the colocated base station 124 comprises a DU supporting an Ethernet-based fronthaul interface (such as an O-RAN or eCPRI fronthaul interface), the co-located DU can be coupled to the vMU 112 using a switched Ethernet network). Each base station 124 coupled to the vDAS 100 can also be located remotely from the vMU 112 to which it is coupled. A remote base station 124 can be coupled to the vMU 112 to which it is coupled via a wireless connection (for example, by using a donor antenna to wirelessly couple the remote base station 124 to the vMU 112 using an analog RF interface) or via a wired connection (for example, where the remote base station 124 comprises a DU supporting an Ethernet-based fronthaul interface (such as an O-RAN or eCPRI fronthaul interface), the remote DU can be coupled to the vMU 112 using an Internet Protocol (IP)-based network such as the Internet).

[0034] The vDAS 100 described here is especially well-suited for use in deployments in which base stations 124 from multiple wireless service operators share the same vDAS 100 (including, for example, neutral host deployments or deployments where one wireless service operator owns the vDAS 100 and provides other wireless service operators with access to its vDAS 100). For example, multiple vMUs 112 can be instantiated, where a different group of one or more vMUs 112 can be used with each of the wireless service operators (and the base stations 124 of that wireless service operator). The vDAS 100 described here is especially well-suited for use in such deployments because vMUs 112 can be easily instantiated in order to support additional wireless service operators. This is the case even if an additional physical server computer 104 is needed in order to instantiate a new vMU 112 because such physical server computers 104 are either already available in such deployments or can be easily added at a low cost (for example, because of the COTS nature of such hardware). Other vDAS entities implemented in virtualized manner (for example, ICNs) can also be easily instantiated or removed as needed based on demand.

[0035] In the example shown in FIGS. 1A-1C, the physical server computer 104 on which each vMU 112 is deployed includes one or more physical donor interfaces 126 that are each configured to communicatively couple the vMU 112 (and the physical server computer 104 on which it is deployed) to one or more base stations 124. Also, the physical server computer 104 on which each vMU 112 is deployed includes one or more physical transport interfaces 128 that are each configured to communicatively couple the vMU 112 (and the physical server computer 104 on which it is deployed) to the fronthaul network 120 (and ultimately the APs 114 and ICNs). Each physical donor interface 126 and physical transport interface 128 is a physical network function (PNF) (for example, implemented as a Peripheral Computer Interconnect Express (PCIe) device) deployed in or with the physical server computer 104.

[0036] In the example shown in FIGS. 1A-1C, each physical server computer 104 on which each vMU 112 is deployed includes or is in communication with separate physical donor and transport interfaces 126 and 128. However, it is to be understood that in other embodiments a single set of physical interfaces 126 and 128 can be used for both donor purposes (that is, communication between the vMU 112 to one or more base stations 124) and for transport purposes (that is, communication between the vMU 112 and the APs 114 over the fronthaul network 120).

[0037] In the exemplary embodiment shown in FIGS. 1A-1C, the physical donor interfaces 126 comprise one or more physical RF donor interfaces (also referred to here as “physical RF donor cards”) 134. Each physical RF donor interface 134 is in communication with one or more vMUs 112 executing on the physical server computer 104 in which that physical RF donor interface 134 is deployed (for example, by implementing the physical RF donor interface 134 as a card inserted in the physical server computer 104 and communicating over a PCIe lane with a central processing unit (CPU) used to execute each such vMU 112). Each physical RF donor interface 134 includes one or more sets of physical RF ports (not shown) to couple the physical RF donor interface 134 to one or more base stations 124 using an analog RF interface. Each physical RF donor interface 134 is configured, for each base station 124 coupled to it, to receive downlink analog RF signals from the base station 124 via respective RF ports, convert the received downlink analog RF signals to digital downlink time-domain user-plane data, and output it to a vMU 112 executing on the same server computer 104 in which that RF donor interface 134 is deployed. Also, each physical RF donor interface 134 is configured, for each base station 124 coupled to it, to receive combined uplink time-domain user-plane data from the vMU 112 for that base station 124, convert the received combined uplink time-domain user-plane data to uplink analog RF signals, and output them to the base station 124. Moreover, the digital downlink time-domain user-plane data produced, and the digital uplink time-domain user-plane data received, by each physical RF donor interface 134 can be in the form of real digital values or complex (that is. in-phase and quadrature (IQ)) digital values and at baseband (that is, centered around 0 Hertz) or with a frequency offset near baseband or an intermediate frequency (IF).

[0038] In the exemplary embodiment shown in FIGS. 1A-1C, the physical donor interfaces 126 also comprise one or more physical CPRI donor interfaces (also referred to here as “physical CPRI donor cards”) 138. Each physical CPRI donor interface 138 is in communication with one or more vMUs 112 executing on the physical server computer 104 in which that physical CPRI donor interface 138 is deployed (for example, by implementing the physical CPRI donor interface 138 as a card inserted in the physical server computer 104 and communicating over a PCIe lane with a CPU used to execute each such vMU 112). Each physical CPRI donor interface 138 includes one or more sets of physical CPRI ports (not shown) to couple the physical CPRI donor interface 138 to one or more base stations 124 using a CPRI interface. More specifically, in this example, each base station 124 coupled to the physical CPRI donor interface 138 comprises a BBU or DU that is configured to communicate with a corresponding RRH or RU using a CPRI fronthaul interface. Each physical CPRI donor interface 138 is configured, for each base station 124 coupled to it, to receive from the base station 124 via a CPRI port digital downlink data formatted for the CPRI fronthaul interface, extract the digital downlink data, and output it to a vMU 112 executing on the same server computer 104 in which that CPRI donor interface 138 is deployed. Also, each physical CPRI donor interface 138 is configured, for each base station 124 coupled to it. to receive digital uplink data including combined digital user-plane data from the vMU 112, format it for the CPRI fronthaul interface, and output the CPRI formatted data to the base station 124 via the CPRI ports.

[0039] In the exemplary embodiment shown in FIGS. 1A-1C, the physical donor interfaces 126 also comprise one or more physical donor Ethernet interfaces 142. Each physical donor Ethernet interface 142 is in communication with one or more vMUs 112 executing on the physical server computer 104 in which that physical donor Ethernet interface 142 is deployed (for example, by implementing the physical donor Ethernet interface 142 as a card or module inserted in the physical server computer 104 and communicating over a PCIe lane with a CPU used to execute each such vMU 112). Each physical donor Ethernet interface 142 includes one or more sets of physical donor Ethernet ports (not shown) to couple the physical donor Ethernet interface 142 to one or more base stations 124 so that each vMU 112 can communicate with the one or more base stations 124 using an Ethernet-based digital fronthaul interface (for example, an 0-RAN or eCPRI fronthaul interface). More specifically, in this example, each base station 124 coupled to the physical donor Ethernet interface 142 comprises a BBU or DU that is configured to communicate with a corresponding RRH or RU using an Ethernet-based fronthaul interface. Each donor Ethernet interface 142 is configured, for each base station 124 coupled to it, to receive from the base station 124 digital dow nlink fronthaul data formatted as Ethernet data, extract the digital downlink fronthaul data, and output it to a vMU 112 executing on the same server computer 104 in which that donor Ethernet interface 142 is deployed. Also, each physical donor Ethernet interface 142 is configured, for each base station 124 coupled to it, to receive digital uplink fronthaul data including combined digital user-plane data for the base station 124 from the vMU 112, output it to the base station 124 via one or more Ethernet ports 144. In some implementations, each physical donor Ethernet interface 142 is implemented using standard Ethernet interfaces of the type typically used with COTS physical servers.

[0040] In the exemplary' embodiment shown in FIGS. 1A-1C, the physical transport interfaces 128 comprise one or more physical Ethernet transport interfaces 146. Each physical transport Ethernet interface 146 is in communication with one or more vMUs 112 executing on the physical server computer 104 in which that physical transport Ethernet interface 146 is deployed (for example, by implementing the physical transport Ethernet interface 146 as a card or module inserted in the physical server computer 104 and communicating over a PCIe lane with a CPU used to execute each such vMU 112). Each physical transport Ethernet interface 146 includes one or more sets of Ethernet ports (not shown) to couple the physical transport Ethernet interface 146 to the Ethernet cabling used to implement the fronthaul network 120 so that each vMU 112 can communicate with the various APs 114 and ICNs. In some implementations, each physical transport Ethernet interface 146 is implemented using standard Ethernet interfaces of the type typically used with COTS physical servers.

[0041] In this exemplary embodiment, the virtualization software 106 is configured to implement within the virtual environment 108 a respective virtual interface for each of the physical donor interfaces 126 and physical transport Ethernet interfaces 146 in order to provide and control access to the associated physical interface by each vMU 112 implemented within that virtual environment 108. That is, the virtualization software 106 is configured so that the virtual entity 110 used to implement each vMU 112 includes or communicates with a virtual donor interface (VDI) 130 that virtualizes and controls access to the underlying physical donor interface 126. Each VDI 130 can also be configured to perform some donor-related signal or other processing (for example, each VDI 130 can be configured to process the user-plane and/or control-plane data provided by the associated physical donor interface 126 in order to determine timing and system information for the base station 124 and associated cell). Also, although each VDI 130 is illustrated in the examples shown in FIGS. 1A-1C as being separate from the respective vMU 112 with which it is associated, it is to be understood that that each VDI 130 can also be implemented as a part of the vMU 112 with which it is associated. Likewise, the virtualization software 106 is configured so that the virtual entity 110 used to implement each vMU 112 includes or communicates with a virtual transport interface (VTI) 132 that virtualizes and controls access to the underlying physical transport interface 128. Each VTI 132 can also be configured to perform some transport-related signal or other processing. Also, although each VTI 132 is illustrated in the examples shown in FIGS. 1A-1C as being separate from the respective vMU 112 with which it is associated, it is to be understood that that each VTI 132 can also be implemented as a part of the vMU 112 with which it is associated. For each port of each physical Ethernet transport interface 146, the physical Ethernet transport interface 146 (and each corresponding virtual transport interface 132) is configured to communicate over a switched Ethernet network or over a point-to-point Ethernet link depending on how the fronthaul network 120 is implemented (more specifically, depending whether the particular Ethernet cabling connected to that port is being used to implement a part of a switched Ethernet network or is being used to implement a point-to-point Ethernet link).

[0042] The vDAS 100 is configured to serv e each base station 124 using a respective subset of APs 114 (which may include less than all of the APs 114 of the vDAS 100). The subset of APs 114 used to serve a given base station 124 is also referred to here as the “simulcast zone” for that base station 124. Typically, the simulcast zone for each base station 124 includes multiple APs 114. In this way, the vDAS 100 increases the coverage area for the capacity provided by the base stations 124. Different base stations 124 (including different base stations 124 from different wireless service operators in deployments where multiple wireless sendee operators share the same vDAS 100) can have different simulcast zones defined for them. Also, the simulcast zone for each served base station 124 can change (for example, based on a time of day, day of week, etc., and/or in response to a particular condition or event). [0043] In general, the wireless coverage of a base station 124 served by the vDAS 100 is improved by radiating a set of downlink RF signals for that base station 124 from the coverage antennas 116 associated with the multiple APs 114 in that base station’s simulcast zone and by producing a single set of uplink base station signals by a combining or summing process that uses inputs derived from the uplink RF signals received via the coverage antennas 116 associated with the multiple APs 114 in that base station's simulcast zone, where the resulting final single set of uplink base station signals is provided to the base station 124.

[0044] This combining or summing process can be performed in a centralized manner in which the combining or summing process for each base station 124 is performed by a single unit of the vDAS 100 (for example, by the associated vMU 112). This combining or summing process can also be performed for each base station 124 in a distributed or hierarchical manner in which the combining or summing process is performed by multiple units of the vDAS 100 (for example, the associated vMU 112 and one or more ICNs and/or APs 114). Each unit of the vDAS 100 that performs the combining or summing process for a given base station 124 receives uplink transport data for that base station 124 from that unit’s one or more “southbound” entities, combines or sums corresponding user-plane data contained in the received uplink transport data for that base station 124 as well as any- corresponding user-plane data generated at that unit from uplink RF signals received via coverage antennas 116 associated with that unit (which would be the case if the unit is a “daisy-chained” AP 114), generates uplink transport data containing the combined userplane data for that base station 124, and communicates the resulting uplink transport data for that base station 124 to the appropriate “northbound” entities coupled to that unit. As used here, “southbound” refers to traveling in a direction “away,” or being relatively “farther,” from the vMU 112 and base station 124, and “northbound” refers to traveling in a direction “towards”, or being relatively “closer” to, the vMU 112 and base station 124. As used here, the southbound entities of a given unit are those entities that are subtended from that unit in the southbound direction, and the northbound entities of a given unit are those entities from which the given unit is itself subtended from in the southbound direction.

[0045] The vDAS 100 can also include one or more intermediary combining nodes (ICNs) (also referred to as “expansion” units or nodes). For each base station 124 that the vDAS 100 serves using an ICN, the ICN is configured to receive a set of uplink transport data containing user-plane data for that base station 124 from a group of southbound entities (that is. from APs 114 and/or other ICNs) and perform the uplink combining or summing process described above in order to generate uplink transport data containing combined user-plane data for that base station 124, which the ICN transmits northbound towards the vMU 112 serving that base station 124. Each ICN also forw ards northbound all other uplink transport data (for example, uplink management-plane and synchronization-plane data) received from its southbound entities. In the embodiments shown in FIGS. 1 A, 1C, 4A, 4C. and 4D, the ICN 103 is communicatively coupled to its northbound entities and its southbound entities using the switched Ethernet network 122 and is used only for communicating uplink transport data and is not used for communicating downlink transport data. In such embodiments, each ICN 103 includes one or more Ethernet interfaces to communicatively couple the ICN 103 to the switched Ethernet network 122. For example, the ICN 103 can include one or more Ethernet interfaces that are used for communicating with its northbound entities and one or more Ethernet interfaces that are used for communicating with its southbound entities. Alternatively, the ICN 103 can communicate with both its northbound and southbound entities via the switched Ethernet network 122 using the same set of one or more Ethernet interfaces.

[0046] In some embodiments, the vDAS 100 is configured so that some ICNs also communicate (forward) southbound downlink transport data received from their northbound entities (in addition to communicating uplink transport data). In the embodiments shown in FIGS. 4A-4D, the ICNs 402 are used in this way. The ICNs 402 are communicatively coupled to their northbound entities and their southbound entities using point-to-point Ethernet links 123 and are used for communicating both uplink transport data and downlink transport data.

[0047] Generally, ICNs can be used to increase the number of APs 114 that can be served by a vMU 112 while reducing the processing and bandwidth load relative to having the additional APs 114 communicate directly with the vMU 112. Each ICN can be implemented as a physical network function using dedicated, special-purpose hardware. Alternatively, each ICN can be implemented as a virtual network function running on a physical server. For example, each ICN can be implemented in the same manner as the vMU 112. [0048] Also, one or more APs 114 can be configured in a “daisy-chain” or “ring” configuration in which transport data for at least some of those APs 114 is communicated via at least one other AP 114. Each such AP 114 would also perform the user-plane combining or summing process described above for any base station 124 served by that AP 114 in order to combine or sum user-plane data generated at that AP 114 from uplink RF signals received via its associated coverage antennas 116 with corresponding uplink userplane data for that base station 124 received from any southbound entity subtended from that AP 114. Such an AP 114 also forwards northbound all other uplink transport data received from any southbound entity subtended from it and forwards to any southbound entity subtended from it all downlink transport received from its northbound entities.

[0049] In general, the vDAS 100 is configured to receive a set of downlink base station signals from each served base station 124, generate downlink base station data for the base station 124 from the set of downlink base station signals, generate dow nlink transport data for the base station 124 that is derived from the downlink base station data for the base station 124, and communicate the downlink transport data for the base station 124 over the fronthaul network 120 of the vDAS 100 to the APs 114 in the simulcast zone of the base station 124. Each AP 114 in the simulcast zone for each base station 124 is configured to receive the downlink transport data for that base station 124 communicated over the fronthaul network 120 of the vDAS 100, generate a set of downlink analog radio frequency (RF) signals from the downlink transport data, and wirelessly transmit the set of downlink analog RF signals from the respective set of coverage antennas 116 associated with that AP 114. The downlink analog RF signals are radiated for reception by UEs 118 served by the base station 124. As described above, the downlink transport data for each base station 124 can be communicated to each AP 114 in the base station’s simulcast zone via one or more intermediary units of the vDAS 100 (such as one or more ICNs or daisy-chained APs 114). Also as described above, if an AP 114 is a part of a daisy chain, the AP 114 will also forward to any southbound entity subtended from that AP 114 all downlink transport received from its northbound entities.

[0050] The vDAS 100 is configured so that a vMU 112 associated with at least one base station 124 performs at least some of the processing related to generating the downlink transport data that is derived from the downlink base station data for that base station 124 and communicating the downlink transport data for the base station 124 over the fronthaul network 120 of the vDAS 100 to the APs 114 in the simulcast zone of the base station 124. In exemplary embodiments shown in FIGS. 1A-1C, a respective vMU 112 does this for all of the served base stations 124.

[0051] In general, each AP 114 in the simulcast zone of a base station 124 receives one or more uplink RF signals transmitted from UEs 118 being served the base station 124. Each such AP 114 generates uplink transport data derived from the one or more uplink RF signals and transmits it over the fronthaul network 120 of the vDAS 100. As noted above, as a part of doing this, if the AP 114 is a part of daisy chain, the AP 114 performs the user-plane combining or summing process described above for the base station 124 in order to combine or sum user-plane data generated at that AP 114 from uplink RF signals received via its associated coverage antennas 116 for the base station 124 with any corresponding uplink user-plane data for that base station 124 received from any southbound entity subtended from that AP 114. Such a daisy -chained AP 114 also forwards northbound to its northbound entities all other uplink transport data received from any southbound entity subtended from that AP 114. As described above, the uplink transport data for each base station 124 can be communicated from each AP 114 in the base station's simulcast zone over the fronthaul network 120 via one or more intermediary units of the vDAS 100 (such as one or more ICNs or daisy-chained APs 114).

[0052] The vDAS 100 is configured to receive uplink transport data for each base station 124 from the fronthaul network 120 of the vDAS 100, use the uplink transport data for the base station 124 received from the fronthaul network 120 of the vDAS 100 to generate uplink base station data for the base station 124, generate a set of uplink base station signals from the uplink base station data for the base station 124, and provide the uplink base station signals to the base station 124. As a part of doing this, the user-plane combining or summing process can be performed for the base station 124.

[0053] The vDAS 100 is configured so that a vMU 112 associated with at least one base station 124 performs at least some of the processing related to using the uplink transport data for the base station 124 received from the fronthaul network 120 of the vDAS 100 to generate the uplink base station data for the base station 124. In exemplary embodiments shown in FIGS. 1A-1C, a respective vMU 112 does this for all of the served base stations 124. As a part of performing this processing, the vMU 112 can perform at least some of the user-plane combining or summing process for the base station 124. [0054] Also, for any base station 124 coupled to the vDAS 100 using a CPRI fronthaul interface or an Ethernet fronthaul interface, the associated vMU 112 (and/or VDI 132 or physical donor interface 126) is configured to appear to that base station 124 (that is, the associated BBU or DU) as a single RU or RRH of the type that the base station 124 is configured to work with (for example, as a CPRI RU or RRH where the associated BBU or DU is coupled to the vDAS 100 using a CPRI fronthaul interface or as an 0-RAN, eCPRI. or RoE RU or RRH where the associated BBU or DU is coupled to the vDAS 100 using an 0-RAN, eCPRI, or RoE fronthaul interface). As a part of doing this, the vMU 112 (and/or VDI 132 or physical donor interface 126) is configured to implement the controlplane, user-plane, synchronization-plane, and management-plane functions that such a RU or RRU would implement. Stated another way, in this example, the vMU 112 (and/or VDI 132 or physical donor interface 126) is configured to implement a single ‘’virtual’’ RU or RRH for the associated base station 124 even though multiple APs 114 are actually being used to wirelessly transmit and receive RF signals for that base station 124.

[0055] In some implementations, the content of the transport data and the manner it is generated depend on the functional split and/or fronthaul interface used to couple the associated base station 124 to the vDAS 100 and, in other implementations, the content of the transport data and the manner in which it is generated is generally the same for all donor base stations 124, regardless of the functional split and/or fronthaul interface used to couple each donor base station 124 to the vDAS 100. More specifically, in some implementations, whether user-plane data is communicated over the vDAS 100 as time-domain data or frequency-domain data depends on the functional split used to couple the associated donor base station 124 to the vDAS 100. That is, where the associated donor base station 124 is coupled to the vDAS 100 using functional split 7-2 (for example, where the associated donor base station 124 comprises an O-RAN DU that is coupled to the vDAS 100 using the 0-RAN fronthaul interface), transport data communicated over the fronthaul network 120 of the vDAS 100 comprises frequency -domain user-plane data and any associated controlplane data. Where the associated donor base station 124 is coupled to the vDAS 100 using functional split 8 (for example, where the associated donor base station 124 comprises a CPRI BBU that is coupled to the vDAS 100 using the CPRI fronthaul interface) or where the associated donor base station 124 is coupled to the vDAS 100 using an analog RF interface (for example, where the associated donor base station 124 comprises a “complete” base station that is coupled to the vDAS 100 using the analog RF interface that otherwise be used to couple the antenna ports of the base station to a set of antennas), transport data communicated over the fronthaul network 120 of the vDAS 100 comprises time-domain user-plane data and any associated control-plane data.

[0056] In some implementations, user-plane data is communicated over the vDAS 100 in one form (either as time-domain data or frequency-domain data) regardless of the functional split used to couple the associated donor base station 124 to the vDAS 100. For example, in some implementations, user-plane data is communicated over the vDAS 100 as frequency-domain data regardless of the functional split used to couple the associated donor base station 124 to the vDAS 100. Alternatively, user-plane data can be communicated over the vDAS 100 as time-domain data regardless of the functional split used to couple the associated donor base station 124 to the vDAS 100. In implementations where user-plane data is communicated over the vDAS 100 in one form, user plane data is converted as needed (for example, by converting time-domain user plane data to frequencydomain user plane data and generating associated control plane data or by converting frequency-domain user plane data to time-domain user plane data and generating associated control plane data as needed).

[0057] In some such implementations, the same fronthaul interface can be used for transport data communicated over the fronthaul network 120 of the vDAS 100 for all the different types of donor base stations 124 coupled to the vDAS 100. For example, in implementations where user-plane data is communicated over the vDAS 100 in different forms, the 0-RAN fronthaul interface can be used for transport data used to communicate frequency-domain user-plane data and any associated control-plane data for donor base stations 124 that are coupled to the vDAS 100 using functional split 7-2 and the 0-RAN fronthaul interface can also be used for transport data used to communicate time-domain user-plane data and any associated control-plane data for donor base stations 124 that are coupled to the vDAS 100 using functional split 8 or using an analog RF interface. Also, in implementations where user-plane data is communicated over the vDAS 100 in one form (for example, as frequency-domain data), the 0-RAN fronthaul interface can be used for all donor base stations 124 regardless of the functional split used to couple the associated donor base station 124 to the vDAS 100.

[0058] Alternatively, in some such implementations, different fronthaul interfaces can be used to communicate transport data for different types of donor base stations 124. For example, the O-RAN fronthaul interface can be used for transport data used to communicate frequency-domain user-plane data and any associated control-plane data for donor base stations 124 that are coupled to the vDAS 100 using functional split 7-2 and a proprietary fronthaul interface can be used for transport data used to communicate timedomain user-plane data and any associated control-plane data for donor base stations 124 that are coupled to the vDAS 100 using functional split 8 or using an analog RF interface.

[0059] In some implementations, transport data is communicated in different ways over different portions of the fronthaul network 120 of the vDAS 100. For example, the way transport data is communicated over portions of the fronthaul network 120 of the vDAS 100 implemented using switched Ethernet networking can differ from the way transport data is communicated over portions of the fronthaul network 120 of the vDAS 100 implemented using point-to-point Ethernet links 123 (for example, as a described below in connection with FIGS. 4A-4D).

[0060] In the exemplary embodiment shown in FIGS. 1A-1C, the vDAS 100, and each vMU 112, ICN, and AP 114 thereof, is configured to use a time synchronization protocol (for example, the Institute of Electrical and Electronics Engineers (IEEE) 1588 Precision Time Protocol (PTP) or the Synchronous Ethernet (SyncE) protocol) to synchronize itself to a timing master entity established for the vDAS 100. In one example, one of the vMUs 112 is configured to serve as the timing master entity for the vDAS 100 and each of the other vMUs 112 and the ICNs and APs 114 synchronizes itself to that timing master entity. In another example, a separate external timing master entity is used and each vMU 112, ICN, and AP 114 synchronizes itself to that external timing master entity.

[0061] In the exemplary embodiment shown in FIGS. 1A-1C, each vMU 112 (and/or the associated VDIs 130) can also be configured to process the downlink user-plane and/or control-plane data for each donor base station 124 in order to determine timing and system information for the donor base station 124 and associated cell. This can involve processing the downlink user-plane and/or control-plane data for the donor base station 124 to perform the initial cell search processing a UE would typically perform in order to acquire time, frequency, and frame synchronization with the base station 124 and associated cell and to detect the Physical layer Cell ID (PCI) and other system information for the base station 124 and associated cell (for example, by detecting and/or decoding the Primary Synchronization Signal (PSS). the Secondary Synchronization Signal (SSS). the Physical Broadcast Channel (PBCH), the Master Information Block (MIB). and System Information Blocks (SIBs)). This timing and system information for a donor base station 124 can be used, for example, to configure the operation of the vDAS 100 (and the components thereof) in connection with serving that donor base station 124.

[0062] In order to reduce the latency associated with implementing each vMU 112 or ICN in a virtualized environment 108 running on a COTS physical server 104, input-output (IO) operations associated with communicating data between a vMU 112 and a physical donor interface 126 and/or between a vMU 112 and a physical transport interface 128, as wel 1 as any baseband processing performed by a vMU 112, associated VDI 130, or ICN can be time-sliced to ensure that such operations are performed in a timely manner. With such an approach, the tasks and threads associated with such operations and processing are executed in dedicated times slices without such tasks and threads being preempted by, or otherwise having to wait for the completion of, other tasks or threads.

[0063] As discussed in the background section, to improve wireless communications, MIMO technology might be utilized. MIMO refers to a technology used in communication systems to improve performance by using multiple antennas at both transmitter and receiver ends. In a traditional communication system (e.g., in a Single Input Single Output (SISO) system), there is one antenna at the transmitter end and one at the receiver end. On the other hand. MIMO systems use multiple antennas at both transmitter and receiver ends. Substantial improvements may be realized utilizing MIMO techniques with respect to the traditional SISO systems. MIMO systems have capabilities that allow' them to fully exploit the multi-path richness of a wireless channel. This is in contrast with traditional techniques that try to counteract multi-path effects rather than embrace them. MIMO systems generally rely upon multi-element antennas at both of the ends of the communication links, such as in the base station and also in the wireless device. In addition to desirable beam-forming and diversity⁷ characteristics, MIMO systems also may provide spatial multiplexing gain, which allows multi data streams to be transmitted over spatially-independent parallel subchannels. This may lead to a significant increase in the system capacity without extending the bandwidth requirements. Generally, the SISO system cannot increase spectral efficiency by taking advantage of spatial MIMO technology'.

[0064] Massive MIMO (M-MIMO) is an extension of traditional MIMO technology that involves using a very large number of antennas at the base station or access point. While traditional MIMO systems might have a few antennas (e.g., 2 to 4) at the transmitter and receiver ends, massive MIMO systems can have tens or even hundreds of antennas at the transmitter and receiver ends. The concept of massive MIMO was introduced as a way to further enhance the performance of wireless communication systems, particularly in terms of spectral efficiency, energy efficiency, and overall system capacity'. Massive MIMO may play a crucial role in meeting the growing demand for high data rates and improved network performance in densely populated areas.

[0065] The Massive MIMO systems available today have certain limitations. For example, there is a limit on number of antennas, typically the antenna count in existing Massive MIMO systems is medium, which restricts the system's ability to fully exploit the advantages of massive antenna arrays. The antenna spacing is inadequate (typically, ranging from low to medium antenna spacing); the rank measured by a UE 118, representing a number of independent antenna paths seen by the UE 118, tends to be low; processing at distributed unit of the base station is complex and high, contributing to performance degradation. Additionally, channel sensitivity is high resulting in further performance degradation. The existing M-MIMO systems lack dynamically adaptability and multi-operator support, and have fixed (or non-flexible) configuration for donor base stations 124. The existing M-MIMO systems have a smaller number of parallel streams available, data routing is fixed, and complexity at the APs 114 is also high. In the existing M-MIMO systems, physical sectorization is typically driven mainly by the distributed unit, resulting in complexity. The ports of the APs 114 are physical ports, size of M-MIMO system is huge leading to increased power consumption and high transmit power. The existing M-MIMO systems support a fixed type of APs 114.

[0066] To address these and other limitations of the existing M-MIMO systems, there is a need for further improvements in the technology. The present disclosure overcomes these and other limitations by achieving M-MIMO like effect using Distributed Antenna Systems. Such DAS-driven M-MIMO systems effectively overcome the aforementioned limitations of the existing M-MIMO systems and offers several advantages, which are discussed in the forthcoming paragraphs. It may be noted that the techniques of the present disclosure are applicable for traditional DAS which comprises a physical MU as well as for virtualized DAS which comprises the vMU 112. [0067] Within the DAS, a plurality of APs 114 are deployed across a geographical region and each AP 114 is equipped with N antennas. When M APs 114 of the plurality of APs 114, each hosting N antennas, are co-located (e.g., the AP 114 are situated in close proximity to each other, possibly in the same physical location or within a small area), it gives the appearance of a cumulative N*M antennas, which forms basis of the proposed D AS-driven M-MIMO system. It may be noted that the different AP 114 are provided with sufficient spacing to ensure adequate antenna spacing. The DAS receives a single input or downlink signal from the donor base station 124 and the same downlink signal is radiated across the geographical region from the plurality of AP 114.

[0068] As per standard Open Radio Access Network (O-RAN) protocol, the donor base station 124 transmits a request message (also known as "a capability request’⁷) to the DAS (particularly, to the vMU 112 of the DAS), soliciting capability information regarding capabilities of the APs 114 deployed in the DAS. The capability information may comprise details like a number of antennas supported by each AP 114, a frequency of operations supported by the AP 114, the simultaneous carriers supported by the AP 114 in terms of channel bandwidth, a maximum transmission power per antenna port for the AP 114, support for Time Division Duplex (TDD) and/or Frequency Division Duplex (FDD) operations by the AP 114, but not limited thereto.

[0069] In the DAS, the capability request from the donor base station 124 is relayed to the processing module of the DAS (e.g., the vMU 112), and is then transmitted unchanged to the plurality of APs 114. Subsequently, the plurality of APs 114 receive the capability request, process the received requests and communicate their capabilities or capability information back to the donor base station 124 via the vMU 112. In this manner, the donor base station 124 becomes aware of the capabilities of the plurality of APs 114 and accordingly the donor base station 124 schedules transmissions for the plurality of APs 114. In one non-limiting embodiment, instead of sending the capability information of each of the plurality of APs 114, the vMU 112 may send capability information associated with only one AP 114 to the donor base station 124 (e.g., when all of the plurality of APs 114 are identical).

[0070] In order to implement the DAS-driven M-MIMO system, the present disclosure proposes to generate or form at least one group of APs 114 from the plurality of APs 114 and then communicating combined capability information of each of the at least one group of APs 114 back to the donor base station 124. Initially, the vMU 112 receives a capability request from the donor base station 124 soliciting capability information of the DAS (particularly, capability information of the plurality of APs 114 deployed in the DAS). The vMU 112 may then forward the received capability request to the plurality of APs 114 requesting the plurality of APs 114 to transmit back their respective capability information. Each of the plurality of APs 114 receives the capability request, processes the received requests, and communicates its capability information back to the donor base station 124 via the vMU 112 (e.g., in an uplink message). Thus, the vMU 112 receives a plurality of (uplink) capability information messages from the plurality of APs 114 (i.e., the vMU 112 receives one capability information messages from each AP 114 of the plurality of APs 114)

[0071] A capability information messages may comprise the capability information indicating at least a number of coverage antennas 116 associated with or supported by the corresponding AP 114. The capability information may comprise additional information such as a frequency of operations supported by the AP 114. the simultaneous carriers supported by the AP 114 in terms of channel bandwidth, a maximum transmission power per antenna port for the AP 114, support for TDD and/or FDD operations by the AP 114, but not limited thereto.

[0072] The vMU 112, instead of sending the capability information message to the donor base station 124, may process the received plurality of capability information messages. In an aspect, processing the received plurality' of capability information messages may comprise generating at least one group of APs 114 from the plurality of APs 114 and consequently, generating at least one combined capability information message corresponding to the at least one group of APs. The grouping helps in organizing and managing the capabilities of multiple APs 114 collectively. A combined capability information message associated with a group of APs 114 may comprise combined capability information of the group of APs 114 and the combined capability information may comprise at least a number of coverage antennas associated with the group of APs 114. However, the present disclosure is not limited thereto, and the combined capability information may additionally comprise a frequency of operations supported by the group of APs 114, the simultaneous carriers supported by the group of APs 114 in terms of channel bandwidth, a maximum transmission power per antenna port for the group of APs 114, support for TDD and/or FDD operations by the group of APs 114, but not limited thereto.

[0073] The vMU 112 may then transmit the at least one combined capability information message to the donor base station 124. In one non-limiting embodiment, instead of sending the at least one combined capability information message for the at least group of APs 114 (i.e. , one combined capability information message for each group of APs 114), the vMU 112 may send capability information associated with only one group of APs 114 to the donor base station 124 (e.g., when all groups of APs 114 have same number of APs 114 with identical configurations). The donor base station 124 considers the group of APs 114 as a single AP (e.g., a single virtual AP) and accordingly schedules transmissions for the single AP taking into account the aggregated capabilities of the group of APs 114. In this manner, vMU 112 advertises each group of APs 114 as a single virtual AP (vAP) to the donor base station 124, thereby forming the DAS-driven Massive MIMO system and creating the Massive-MIMO effect.

[0074] Consider an example, where there are 40 co-located APs 114 deployed in a DAS and each AP 114 hosts 4 coverage antennas. As per standard O-RAN protocol, the donor base station 124 transmits the capability request to the DAS soliciting capability information of the APs 114 deployed in the DAS. The vMU 112 receives the capability request from the donor base station 124 and forwards the received capability request to each of the 40 APs 114 requesting them to transmit back their respective capability information. Each of the 40 APs 114 receives the capability request, processes the received requests, and communicates its capability information back to the vMU 112. Thus, the vMU 112 receives 40 capability information messages from the 40 APs 114. A capability information messages may indicate at least that the AP 114 supports 4 coverage antennas. The vMU 112 may process the received capability- information messages to generate at least one group of APs 114 from the plurality- of APs 114. Consider that the vMU divides the 40 APs 114 into 4 groups depending on their geographical locations, each having 10 APs 114 and then generates 4 combined capability information message corresponding to the 4 group of APs. Each capability information messages may indicate each group of APs 114 supports 40 coverage antennas.

[0075] The vMU 112 may then transmit 4 combined capability information messages to the donor base station 124 (i.e.. one combined capability information message for each group). Alternatively, the vMU 112 may send only one combined capability information message to the donor base station 124 (e.g., when all 4 groups of APs 114 have same/similar combined capability information). The donor base station 124 considers each group of 10 APs 114 as a single AP and accordingly schedules transmissions for the single AP taking into account the aggregated capabilities of the group of APs 114. Said differently, the donor base stations assumes that each AP has 40 antennas and accordingly configures its Massive- MIMO modes and schedules transmissions for the APs, thereby forming DAS-driven M- MIMO system.

[0076] In one non-limiting embodiment, the vMU 112 may be configured to schedule downlink transmissions for each UE 118 using the at least one group of APs depending on uplink rank indicator message received from the UEs 118. Uplink Rank Indicator (RI) messages are commonly used in wireless communication systems to provide feedback from UEs 118 to the network about observed channel conditions. Each UE communicates its uplink rank indicator message independently. Generally, a rank or rank indicator of a UE may refer to a number of independent antenna paths or spatial streams that the UE 118 can observe or can effectively distinguish. Each uplink rank indicator message includes information about the number of independent antenna paths observed by the corresponding UE. Based on the received uplink rank indicator messages, the network (or more specifically, the vMU 112) may make informed decisions about scheduling downlink transmissions to each UE. This helps in determining appropriate MIMO transmission schemes and/or resource allocations for the downlink transmissions.

[0077] In the proposed DAS-driven M-MIMO system, the vMU 112 is responsible for grouping the plurality of APs 114 within the DAS to form the at least one group of APs. In one non-limiting embodiment, the vMU 112 may be configured to generate the at least one group of APs by performing random grouping of the plurality of APs 114. For instance, the vMU 112 may randomly divide the plurality’ of APs 114 into the at least one group. As an example, if there are 10 APs in the DAS, the vMU 112 may randomly form two groups of APs, Group A with 4 APs and Group B with 6 APs. Such grouping is not predetermined but is instead determined by chance. In one example, the vMU 112 may group all of the plurality of APs 114 into a single group. It may be noted that each group of APs 114 may comprise at least one AP and one AP may be a part of multiple groups of APs. [0078] In one non-limiting embodiment, the vMU 112 may be configured to periodically perform re-grouping of the randomly grouped APs 114 based on one or more predefined factors to adapt to dynamically changing network conditions e.g., changing distribution of UEs, changing network loads, changing network configurations, but not limited thereto. The goal of performing re-grouping may be to maximize link qualities associated with the plurality of UEs 118. Alternatively or additionally, the goal of performing re-grouping may be to maximize rank indicators associated with the plurality of UEs 118. As mentioned above, a rank indicator for a UE indicates a number of independent antenna paths observed by the UE 118. A higher rank indicator indicates that the UE is capable of observing more independent antenna paths, leading to better MIMO performance.

[0079] The re-grouping may be carried out based on one or more factors such as geographical location of APs 114, distances of the APs 114 with respect to each other and with respect to the UEs 118, signal strength or signal qualities observed by the UEs 118, interferences observed by the UEs 118, a number of UEs 118 located within a particular geographical region, or any other relevant criteria. In one non-limiting embodiment, the vMU 112 may avoid performing re-grouping of the APs 114 e.g., when the random grouping of APs yields maximum ranks measured by the UEs 118. In one non-limiting embodiment, instead of performing random grouping of the plurality of APs 114, the vMU 112 may perform the initial grouping of the APs 114 depending on at least one of the one or more factors.

[0080] In one non-limiting embodiment, the vMU 112 may be configured to group or regroup the APs 114 depending on their geographical locations. The vMU 112 may organize the APs that are situated in similar or specific geographic areas into the same group. The vMU 112 may utilize Global Positioning System (GPS) coordinates or any other location related information associated with each AP to form the groups of APs. The geographical locations of various APs within a deployment is typically static and, the vMU 112 is generally aware of the geographical locations of the various APs since the time of deployment and may utilize the same information to generate the at least one group of APs.

[0081] In another non-limiting embodiment, the vMU 112 may be configured to group or re-group the APs 114 depending on physical distances among them. For instance, the vMU 112 may utilize information about physical distance between different APs to form the at least one group of APs 114. The APs 114 that are nearby or that are in close proximity to

Z1 each other may be placed into the same group. The physical distance between different APs may be determined based on GPS coordinates of the APs, physical locations of the APs, using information about the signal strength measurements between different APs, but not limited thereto.

[0082] In another non-limiting embodiment, the vMU 112 may be configured to group or re-group the APs 114 depending on signal strength measurements (e.g., Received Signal Strength Indicators (RSSI)) observed by the UEs 118. As an example, the UEs 118 are configured to periodically measure signal strengths of the APs in their vicinity and report the measured signal strength measurements to the vMU 112. Generally, a signal strength measurement of an AP reflects the quality of signal received by the UE from said AP. In such deployment, a common criterion is to group APs that provide the best signal strength to a specific UE into the same group. In other words, for each UE, the vMU 112 may identity⁷ the APs that provide a signal strength higher than a predefined threshold value. Such APs are grouped together to ensure that each UE is associated with a group of APs providing strongest signals. In one example, the vMU 112 may perform measurements of uplink (UL) signals received from for a given UE, specifically the Uplink Synchronization Reference Signals (UL-SRS) and Physical Random Access Channel (PRACH) signals and based on these measurements, the vMU 112 may perform grouping or re-grouping of APs 114

[0083] In another non-limiting embodiment, the vMU 112 may be configured to group or re-group the APs 114 depending on interference observed by the UEs 118. As an example, the UEs 118 are configured to periodically report interference measurements to the vMU 112. These measurements may include information about signal -to-noise ratio, interference levels from neighboring APs. but not limited thereto. The vMU 112 may process the received measurements to identity' interference based on the received measurements. For example, interference might be detected when the signal-to-noise ratio drops below a certain threshold value and/or when the interference level exceeds above a threshold value. The vMU 112 may dynamically analyze the measurements received from the UEs 118 and based on the analysis, the vMU 112 may form groups of APs with minimal interference. The APs that are identified as causing interference to each other (or to a UE) are not grouped together, ensuring that the UE experiences reduced interference from the neighboring APs. [0084] In another non-limiting embodiment, the vMU 112 may be configured to group or re-group the APs 114 depending on a number of UEs located within a particular region (or depending on UE density). As an example, the vMU 112 is configured to continuously monitors the density of UEs in different regions within a coverage area. As an example, the density of UEs may be monitored using periodic reports from UEs, by analyzing UE handover events, but not limited thereto. Depending on the monitored density of UEs, the vMU 112 may be configured to form groups of APs 114 for identified high-density regions. For instance, the APs 114 within a high density region may be grouped together to collectively address the demand for connectivity in that region.

[0085] In another non-limiting embodiment, one or more factors responsible for performing grouping and/or re-grouping may comprise transmissions of known noisy sequence or known reference signals. For instance, the vMU 112 may configure each AP of the plurality of APs 114 to transmit a known reference signal towards remaining APs 114 of the plurality of APs 114. The known reference signal is received by the remaining APs 114 of the plurality of APs 114 which then perform measurements of at least one parameter with respect to the AP that initially transmitted the reference signal (also referred to as “initiating AP”) and report the measurements to the vMU 112. The at least one parameter may be indicative of proximity of the initiating AP with the remaining APs and may include amplitude difference and phase difference as observed by each of the receiving APs 114 (with respect to the initiating AP). Based on the measured parameters, the vMU 112 may calculate the gain and time delays between the initiating AP and each of the remaining APs 114. The gain and time delays provide information about the proximity or closeness of each AP to the initiating AP and are therefore utilized to identify APs 114 that are in close proximity to the initiating AP. The process is repeated for each AP and the closer APs are grouped together to form the at least one group of APs to maximize rank indicators associated with the UEs 118.

[0086] In one non-limiting embodiments, the vMU 112 may be configured to generate a multi-dimensional matrix comprising the measurements indicative of proximities or distances among different APs 114 of the plurality⁷ of APs 114. As an example, the measurements may comprise the gain and time delay measurements obtained from the known reference signal transmissions. The vMU 112 may utilize the multi-dimensional matrix to generate the at least one group of APs based on the measurements indicative of the proximities. [0087] In one non-limiting embodiment, the multi-dimensional matrix may be known as or may comprise a channel matrix. The channel matrix may comprise precoding or precoder matrix which is a matrix that is applied to the downlink data signals before transmission to improve signal characteristics. In one non-limiting embodiment, the vMU 112 may extend a group of APs to include one or more little bit farther APs to further increase UE rank. To do this, the vMU 112 may configure the one or more farther APs to process the downlink signals to be transmitted towards at least one associated UE using the precoding matrix for improving the signal characteristics. For instance, the vMU 112 may configure the one or more far APs to process downlink signals, to be transmitted towards the associated at least one UE of the plurality of UEs 118. using the precoding matrix for maximizing received signal strength at the at least one UE. Hence, the incoming signals are processed using the precoder matrices so that the signals of all APs (including the farther APs and the APs which are part of group) reach with equal signal characteristics i.e., equal gain and time delay. Likewise, the vMU 112 may configure the one or more for APs to process uplink signals, transmitted by the at least one UE, using the precoding matrix for maximizing received signal strength at the one or more APs.

[0088] In this manner, the vMU 112 generates the at least one group of APs 114 transmits combined capability information message(s) to the donor base station 124. The donor base station 124 considers each group of APs 114 as a single AP cluster (e.g., a single virtual AP) and accordingly schedules transmissions for the single AP cluster taking into account the aggregated capabilities of the group of APs 114. It may be noted that the single AP cluster enables beamforming to support directed communications towards UEs and APs. Additionally, forming the cluster of APs 114 allows for collective processing of measurements obtained across all APs of the cluster rather than handling measurements independently from each AP. This combined processing reduces overhead associated with uplink (UL) measurements and feedback in the Massive MIMO system.

[0089] The proposed DAS driven M-MIMO system has several advantages. For instance, the proposed DAS driven M-MIMO system supports multiple O-RAN split capabilities and multiple types of APs and hence, allows for a wide range of configurations in terms of split capabilities and AP types. For instance, the M-MIMO system implemented using DAS comprises high antenna count, very high antenna spacing, the rank measured by UE (which is the number of independent antenna paths seen by UE) is high, processing at distributed unit of the base station is low, Channel sensitivity is low thereby avoiding performance degradation, Such M-MIMO systems is dynamically adaptable and supports multi operator M-MIMO. The donor base station aware configuration is flexible, there are higher number of parallel streams which are always available; data routing is dynamic and is based on deployment, complexity at AP of base station is low, physical sectorization is combinedly driven by the DU and MU, ports of the AP are virtualized ports, size of M-MIMO system is low and distributed to multiple APs, power consumption is also low and distributed to multiple APs and even the transmit power of low and distributed to multiple APs. Such M- MIMO system supports a different types of APs and functional splits e.g., by way of software upgrades.

[0090] Referring now to FIG. 2 which illustrates a block diagram 200 of an apparatus, in accordance with some embodiments of the present disclosure. The apparatus 200 may comprise at least one transmitter 202, at least one receiver 204, at least one processor 208, at least one memoiy 210, at least one interface 212, and at least one antenna 214. The at least one transmitter 202 may be configured to transmit data/information to one or more nodes/devices using the antenna 214 and the at least one receiver 204 may be configured to receive data/information from the one or more nodes/devices using the antenna 214. The at least one transmitter and receiver may be collectively implemented as a single transceiver module 606. In one non-limiting embodiment, the at least one processor 208 may be communicatively coupled with the transceiver 206, the memory 210, the interface 212, and antenna 214.

[0091] The at least one processor 208 may include, but not restricted to, microprocessors, microcomputers, micro-controllers, central processing units, state machines, logic circuitries, and/or any devices that manipulate signals based on operational instructions. A processor may also be implemented as a combination of computing devices, e.g., a combination of a plurality of microprocessors or any other such configuration. The at least one memory 210 may be communicatively coupled to the at least one processor 208 and may comprise various instructions. The at least one memory 210 may include a Random- Access Memory (RAM) unit and/or a non-volatile memoiy unit such as a Read Only Memory (ROM), optical disc drive, magnetic disc drive, flash memory. Electrically Erasable Read Only Memory (EEPROM), a memory space on a server or cloud and so forth. The at least one processor 208 may be configured to execute one or more instructions stored in the memory 210. [0092] The interfaces 212 may include a variety of software and hardware interfaces, for example, a web interface, a graphical user interface, an input device-output device (I/O) interface, a network interface and the like. The I/O interfaces may allow the apparatus 200 to communicate with one or more nodes/devices either directly or through other devices. The network interface may allow the apparatus 200 to interact with one or more networks either directly or via any other network.

[0093] In one non-limiting embodiment, the apparatus 200 may implement functionalities of any of: the (virtualized) DAS. a base station, an access point 114. a physical master unit, a UE 118, or a part thereof. In another non -limiting embodiment, the apparatus 200 may implement functionalities of the physical sen' er computers 104 on which the vMUs 112 are deployed.

[0094] Referring now to FIG. 3. a flowchart is described illustrating an exemplary method 300 method of providing wireless communication using a DAS, according to an embodiment of the present disclosure. The DAS comprises a MU communicatively coupled with a donor BS, and a plurality' of APs or RUs 114 communicatively coupled with the MU and configured to wirelessly communicate with a plurality of UEs 118 via a respective set of one or more coverage antennas 116.

[0095] The method 300 is merely provided for exemplary' purposes, and embodiments are intended to include or otherwise cover any methods or procedures for wireless communications. The various operations/steps of the method may be performed by’ a master unit or by the at least one processor 208. In one non-limiting embodiment, the DAS comprises a virtual DAS (vDAS 100 and the MU comprises a virtual MU 112. The vDAS comprises at least one physical server computer 104 configured to execute virtualization software 106 that creates a virtualized environment 108, and where the at least one physical server computer 104 is configured to instantiate and execute a set of one or more virtual network functions used to implement the vMU. And where the physical server computer 104 is communicatively coupled to the plurality' of APs using a fronthaul network 120. In such configuration, the various steps may be performed by at least one physical server computer 104 (and more specifically, by the at least one processor 208).

[0096] At block 302, the method 300 may include receiving a plurality of capability information messages from the plurality' of APs 114, where each capability' information message comprises information indicating at least a number of coverage antennas 116 associated with a corresponding AP 114.

[0097] At block 304, the method 300 may include generating at least one group of APs 114 from the plurality of APs 114 by processing the plurality of capability information messages.

[0098] At block 306, the method 300 may include generating at least one combined capability information message corresponding to the at least one group of APs 114. Each combined capability information message may comprise information indicating at least a number of coverage antennas 116 associated with a corresponding group of APs 114.

[0099] In one non-limiting embodiment, the operations of block 304 i.e., generating the at least one group of APs 114 from the plurality of APs 114 may comprise generating the at least one group of APs 114 by performing random grouping of the plurality of APs 114 based on the plurality of capability information messages.

[0100] In one non-limiting embodiment, the method 300 may further comprise periodically performing regrouping of the randomly grouped APs 114 based on one or more predefined factors to maximize rank indicators associated with the plurality of UEs 118. A rank indicator may comprise or indicate a number of independent antenna paths observed by a corresponding UE of the plurality of UEs 118. and the one or more predefined factors may comprise rank indicators associated with the plurality of UEs 118. signal qualities observed by the plurality of UEs 118, interferences observed by the plurality of UEs 118, a number of UEs located within a particular region.

[0101] In one non-limiting embodiment, the operations of block 304 i.e., generating the at least one group of APs 114 from the plurality of APs 114 or the operations of periodically performing the regrouping of the randomly grouped APs 114 may comprises for each AP 114 of the plurality of APs 114, configuring the AP 114 to transmit a known reference signal towards remaining APs 114 of the plurality of APs 114 and receiving measurements of at least one parameter from each of the remaining APs. The measurements of the at least one parameter received from a particular AP of the remaining APs may be an indicative of proximity of the AP 114 with the particular AP. The method 300 may comprise based on the received measurements, generating a multi-dimensional matrix comprising the measurements indicative of proximity among different APs 114 of the plurality of APs 114 and generating the at least one group of APs 114 based on the proximity among the different APs 114 of the plurality of APs 114.

[0102] In one non-limiting embodiment, the multi-dimensional matrix may comprise a precoding matrix and the method 300 may further comprise configuring one or more of the plurality of APs 114 to process downlink signals, to be transmitted towards at least one UE of the plurality of UEs 118. using the precoding matrix for maximizing received signal strength at the at least one UE. The method 300 may also comprise configure the one or more of the plurality of APs 114 to process uplink signals, transmitted by the at least one UE of the plurality⁷ of UEs 118, using the precoding matrix for maximizing received signal strength at the one or more APs 114.

[0103] At block 308, the method 300 may include transmitting the at least one combined capability information message to the donor BS 124 for configuring M-MIMO operations of the donor BS 124.

[0104] In one non-limiting embodiment, the method 300 may further comprise receiving an uplink rank indicator message from each UE of the plurality of UEs 118. The rank indicator message may indicate a number of independent antenna paths associated with the DAS which are observed by the UE. The method 300 may further comprise scheduling downlink transmission for the UE based on the number of independent antenna paths observed by the UE.

[0105] In one non-limiting embodiment, the method 300 may further comprise receiving a capability request from the donor BS 124 requesting capability⁷ information of the DAS and transmitting a request to the plurality of APs 114 for the plurality of capability information messages. In one non-limiting embodiment, the method 300 may further comprise advertising each of the at least one group of APs as a single virtual AP (vAP) to create Massive MIMO effect.

[0106] The above method 300 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform specific functions or implement specific abstract data types.

[0107] The various blocks of the method 300 show n in FIG. 3 have been arranged in a generally sequential manner for ease of explanation. However, it is to be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with method 300 (and the blocks shown in FIG. 3) can occur in a different order (for example, where at least some of the processing associated with the blocks is performed in parallel and/or in an event-driven manner). Additionally, individual blocks may be deleted from the methods without departing from the spirit and scope of the subject matter described herein. Furthermore, the methods can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0108] The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s). Generally, where there are operations illustrated in Figures, those operations may have corresponding counterpart means-plus-function components. It may be noted here that the subject matter of some or all embodiments described with reference to Figures 1A-1C and Figures 4A-4D may be relevant for the methods and the same is not repeated for the sake of brevity.

[0109] Other embodiments can be implemented in other ways. For example, FIGS. 4A-4D illustrates one such embodiment.

[0110] FIGS. 4A-4D are block diagrams illustrating one exemplary embodiment of vDAS 400 in which at least some of the APs 414 are coupled to one or more vMU 112 serving them via one or more intermediate combining nodes (ICNs) 402. Each ICN 402 comprises at least one northbound Ethernet interface (NEI) 404 that couples the ICN 402 to Ethernet cabling used primarily for communicating with the one or more vMUs 112 and a plurality of southbound Ethernet interfaces (SEIs) 406 that couples the ICN 402 to Ethernet cabling used primarily for communicating with one or more of the plurality of APs 414.

[0111] Except as explicitly described here in connection with FIGS. 4A-4D, the vDAS 400 and the components thereof (including the vMU 112) are configured as described above. Also, except as explicitly described here in connection with FIGS. 4A-4D, each AP 414 is implemented in the same manner as the APs 114 described above.

[0112] The ICN 402 comprises one or more programmable devices 410 that execute, or are otherwise programmed or configured by, software, firmware, or configuration logic 412 in order to implement at least some of the functions described here as being performed by an ICN 402 (including, for example, any necessary physical layer (Layer 1) baseband processing). The one or more programmable devices 410 can be implemented in various ways (for example, using programmable processors (such as microprocessors, coprocessors, and processor cores integrated into other programmable devices) and/or programmable logic (such as FPGAs and system-on-chip packages)). Where multiple programmable devices are used, all of the programmable devices do not need to be implemented in the same way.

[0113] The ICN 402 can be implemented as a physical network function using dedicated, special-purpose hardware. Alternatively, the ICN 402 can be implemented as a virtual network function running on a physical server. For example, the ICN 402 can be implemented in the same manner as the vMU 112 described above in connection with FIG.

1

[0114] As noted above, the fronthaul network 420 used for transport between each vMU 112 and the APs 114 and ICNs 402 (and the APs 414 coupled thereto) can be implemented in various ways. Various examples of how the fronthaul network 420 can be implemented are illustrated in FIGS. 4A-4D. In the example shown in FIG. 4A, the fronthaul network 420 is implemented using a switched Ethernet network 422 that is used to communicatively couple each AP 114 and each ICN 402 (and the APs 414 coupled thereto) to each vMU 112 serving that AP 114 or 414 or ICN 402.

[0115] In the example shown in FIG. 4B, the fronthaul network 420 is implemented using only point-to-point Ethernet links 123 or 423, where each AP 114 and each ICN 402 (and the APs 414 coupled thereto) is coupled to each serving vMU 112 serving it via a respective one or more point-to-point Ethernet links 123 or 423. In the example shown in FIG. 4C, the fronthaul network 420 is implemented using a combination of a switched Ethernet network 422 and point-to-point Ethernet links 123 or 423. In the example shown in FIG. 4D, a first ICN 402 has a second ICN 402 subtended from it so that some APs 414 are communicatively coupled to the first ICN 402 via the second ICN 402.

[0116] In one implementation, each vMU 112 that serves the ICN 402 treats the ICN 402 as one or more “virtual APs” to which it sends downlink transport data for one or more base stations 124, and from which it receives uplink transport data, for the one or more base stations 124. The ICN 402 forwards the downlink transport data to, and combines uplink transport data received from, one or more of the APs 414 coupled to the ICN 402. In one implementation of such an embodiment, the ICN 402 forw ards the downlink transport data it receives for all the served base stations 124 to all of the APs 414 coupled to the ICN 402 and combines uplink transport data it receives from all of the APs 414 coupled to the ICN 402 for all of the base stations 124 served by the ICN 402.

[0117] In another implementation, the ICN 402 is configured so that a separate subset of the APs 414 coupled to that ICN 402 can be specified for each base station 124 served by that ICN 402. In such an implementation, for each base station 124 served by an ICN 402, the ICN 402 forwards the downlink transport data it receives for that base station 124 to the respective subset of the APs 414 specified for that base station 124 and combines the uplink transport data it receives from the subset of the APs 414 specified for that base station 124. That is. in this implementation, each ICN 402 can be used to forward the downlink transport data for different served base stations 124 to different subsets of APs 414 and to combine uplink transport data the ICN 402 receives from different subsets of APs 414 for different served base stations 124. Various techniques can be used to do this. For example, the ICN 402 can be configured to inspect one or more fields (or other parts) of the received transport data to identify which base station 124 the transport data is associated with. In another implementation, the ICN 402 is configured to appear as different virtual APs for different served base stations 124 and is configured to inspect one or more fields (or other parts) of the received transport data to identify which virtual AP the transport data is intended for.

[0118] In the exemplary embodiments shown in FIGS. 4A-4D, each ICN 402 is configured to use a time synchronization protocol (for example, the Institute of Electrical and Electronics Engineers (IEEE) 1588 Precision Time Protocol (PTP) or the Synchronous Ethernet (SyncE) protocol) to synchronize itself to a timing master entity established for the vDAS 400 by communicating over the switched Ethernet network 122. Each AP 414 coupled to an ICN 402 is configured to synchronize itself to the time base used in the rest of the vDAS 400 based on the synchronous Ethernet communications provided from the ICN 402. Again, as noted above, it is to be understood that FIGS. 1A-1C and 5A-5D illustrate only a few examples of how? the fronthaul network (and the vDAS more generally) can be implemented and that other variations are possible.

[0119] In anon-limiting embodiment of the present disclosure, one or more non-transitory computer-readable media may be utilized for implementing the embodiments consistent with the present disclosure. A computer-readable media refers to any type of physical memory (such as the memory 210) on which information or data readable by a processor may be stored. Thus, a computer-readable media may store one or more instructions for execution by the at least one processor 208, including instructions for causing the at least one processor 208 to perform steps or stages consistent with the embodiments described herein. The term "‘computer-readable media” should be understood to include tangible items and exclude carrier waves and transient signals. By way of example, and not limitation, such computer-readable media can comprise Random Access Memory (RAM), Read-Only Memory (ROM), volatile memory⁷, nonvolatile memory⁷, hard drives, Compact Disc (CD) ROMs, Digital Video Disc (DVDs), flash drives, disks, and any other known physical storage media.

[0120] Thus, certain non-limiting embodiments may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer readable media having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain non-limiting embodiments, the computer program product may include packaging material.

[0121] As used herein, a phrase referring to “at least one” or “one or more” of a list of items refers to any combination of those items, including single members. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c. The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise. A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the disclosed methods and systems.

[0122] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the disclosure be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present disclosure are intended to be illustrative, but not limiting, of the scope of the disclosure, which is set forth in the appended claims. EXEMPLARY EMBODIMENTS

[0123] Example 1 includes a Distributed Antenna System (DAS) comprising a master unit (MU) communicatively coupled with a donor base station (BS), and a plurality of access points (APs) communicatively coupled with the MU and configured to wirelessly communicate with a plurality of user equipment (UEs) via a respective set of one or more coverage antennas, wherein the MU is configured to: receive a plurality of capability information messages from the plurality of APs, wherein each capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding AP; generate at least one group of APs from the plurality of APs by processing the plurality of capability information messages; generate at least one combined capability information message corresponding to the at least one group of APs, wherein each combined capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding group of APs; and transmit the at least one combined capability information message to the donor BS for configuring Massive Multiple-Input-Multiple-Output (M-MIMO) operations of the donor BS.

[0124] Example 2 includes the DAS of Example 1, wherein to generate the at least one group of APs from the plurality of APs, the MU is configured to generate the at least one group of APs by performing random grouping of the plurality of APs based on the plurality of capability information messages.

[0125] Example 3 includes the DAS of any of Examples 1-2, wherein the MU is configured to periodically perform re-grouping of the randomly grouped APs based on one or more predefined factors to maximize rank indicator associated with the plurality of UEs, wherein a rank indicator comprises a number of independent antenna paths observed by a corresponding UE of the plurality of UEs, and wherein the one or more predefined factors comprise rank indicators associated with the plurality of UEs, signal qualities observed by the plurality of UEs, interferences observed by the plurality of UEs, a number of UEs located within a particular region.

[0126] Example 4 includes the DAS of any of Examples 1-3, wherein to generate the at least one group of APs from the plurality of APs or to periodically perform regrouping of the randomly grouped APs, the MU is configured to: for each AP of the plurality of APs: configure the AP to transmit a known reference signal towards remaining APs of the plurality of APs; and receive measurements of at least one parameter from each of the remaining APs, wherein the measurements of the at least one parameter received from a particular AP of the remaining APs are indicative of proximity of the AP with the particular AP; based on the received measurements, generate a multi-dimensional matrix comprising the measurements indicative of proximity among different APs of the plurality of APs; and generate the at least one group of APs based on the proximity among the different APs of the plurality of APs.

[0127] Example 5 includes the DAS of Example 4, wherein the multi-dimensional matrix comprises a precoding matrix, the MU is further configured to: configure one or more of the plurality of APs to process downlink signals, to be transmitted towards at least one UE of the plurality of UEs. using the precoding matrix for maximizing received signal strength at the at least one UE; and configure the one or more of the plurality of APs to process uplink signals, transmitted by the at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the one or more APs.

[0128] Example 6 includes the DAS of any of Examples 1-5, wherein the MU is further configured to: receive an uplink rank indicator message from each UE of the plurality of UEs, wherein the rank indicator message indicates a number of independent antenna paths associated with the DAS which are observed by the UE; and schedule downlink transmission for the UE based on the number of independent antenna paths observed by the UE.

[0129] Example 7 includes the DAS of any of Examples 1-6, wherein the MU is further configured to: receive a capability request from the donor BS requesting capability information of the DAS; and in response to receiving the capability request from the donor BS, transmit a request to the plurality' of APs for the plurality of capability' information messages.

[0130] Example 8 includes the DAS of any of Examples 1-7, wherein the MU is configured to advertise each of the at least one group of APs as a single virtual AP (vAP) to create Massive MIMO effect.

[0131] Example 9 includes the DAS of any of Examples 1-8, wherein the DAS comprises a virtual DAS (vDAS) and the MU comprises a virtual MU (vMU), wherein the vDAS comprises at least one physical server computer configured to execute virtualization software that creates a virtualized environment, and wherein the at least one physical server computer is configured to instantiate and execute a set of one or more virtual network functions (VNFs) used to implement the vMU, and wherein the physical server computer is communicatively coupled to the plurality of APs using a fronthaul network.

[0132] Example 10 includes a method of providing wireless communication using a Distributed Antenna System (DAS) that comprises a master unit (MU) communicatively coupled with a donor base station (BS), and a plurality of access points (APs) communicatively coupled with the MU and configured to wirelessly communicate with a plurality of user equipment (UEs) via a respective set of one or more coverage antennas, the method comprises: receiving a plurality of capability information messages from the plurality of APs, wherein each capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding AP; generating at least one group of APs from the plurality of APs by processing the plurality of capability information messages; generating at least one combined capability information message corresponding to the at least one group of APs. wherein each combined capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding group of APs; and transmitting the at least one combined capability information message to the donor BS for configuring Massive Multiple-Input-Multiple-Output (M-MIMO) operations of the donor BS.

[0133] Example 11 includes the method of Example 10, w herein generating the at least one group of APs from the plurality of APs comprises generating the at least one group of APs by performing random grouping of the plurality of APs based on the plurality of capability information messages.

[0134] Example 12 includes the method of Example 11, further comprising: periodically performing regrouping of the randomly grouped APs based on one or more predefined factors to maximize rank indicators associated with the plurality of UEs, wherein a rank indicator comprises a number of independent antenna paths observed by a corresponding UE of the plurality of UEs, and wherein the one or more predefined factors comprise rank indicators associated with the plurality of UEs, signal qualities observed by the plurality of UEs, interferences observed by the plurality of UEs, a number of UEs located within a particular region. [0135] Example 13 includes the method of any of Examples 10-12, wherein generating the at least one group of APs from the plurality of APs or periodically performing the regrouping of the randomly grouped APs comprises: for each AP of the plurality of APs: configuring the AP to transmit a known reference signal towards remaining APs of the plurality of APs; and receiving measurements of at least one parameter from each of the remaining APs, wherein the measurements of the at least one parameter received from a particular AP of the remaining APs are indicative of proximity of the AP with the particular AP; based on the received measurements, generating a multi-dimensional matrix comprising the measurements indicative of proximity among different APs of the plurality of APs; and generating the at least one group of APs based on the proximity among the different APs of the plurality of APs.

[0136] Example 14 includes the method of Example 13, wherein the multi-dimensional matrix comprises a precoding matrix, the method further comprises: configuring one or more of the plurality of APs to process downlink signals, to be transmitted towards at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the at least one UE; and configure the one or more of the plurality of APs to process uplink signals, transmitted by the at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the one or more APs.

[0137] Example 15 includes the method of any of Examples 10-14, further comprising: receiving an uplink rank indicator message from each UE of the plurality of UEs, wherein the rank indicator message indicates a number of independent antenna paths associated with the DAS which are observed by the UE; and scheduling downlink transmission for the UE based on the number of independent antenna paths observed by the UE.

[0138] Example 16 includes the method of any of Examples 10-15, further comprising: receiving a capability request from the donor BS requesting capability information of the DAS; and in response to receiving the capability request from the donor BS, transmitting a request to the plurality of APs for the plurality of capability information messages.

[0139] Example 17 includes the method of any of Examples 10-16, further comprising: advertising each of the at least one group of APs as a single virtual AP (vAP) to create Massive MIMO effect. [0140] Example 18 includes the method of any of Examples 10-17, wherein the DAS comprises a virtual DAS (vDAS) and the MU comprises a virtual MU (vMU), wherein the vDAS comprises at least one physical server computer configured to execute virtualization software that creates a virtualized environment, and wherein the at least one physical server computer is configured to instantiate and execute a set of one or more virtual network functions (VNFs) used to implement the vMU, and wherein the physical server computer is communicatively coupled to the plurality of APs using a fronthaul network.

Claims

WHAT IS CLAIMED IS

1. A Distributed Antenna System (DAS) comprising a master unit (MU) communicatively coupled with a donor base station (BS), and a plurality of access points (APs) communicatively coupled with the MU and configured to wirelessly communicate with a plurality’ of user equipment (UEs) via a respective set of one or more coverage antennas, wherein the MU is configured to: receive a plurality of capability information messages from the plurality of APs, wherein each capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding AP; generate at least one group of APs from the plurality of APs by processing the plurality of capability information messages; generate at least one combined capability information message corresponding to the at least one group of APs, wherein each combined capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding group of APs; and transmit the at least one combined capability' information message to the donor BS for configuring Massive Multiple-Input-Multiple-Output (M-MIMO) operations of the donor BS.

2. The DAS of claim 1 , wherein to generate the at least one group of APs from the plurality of APs, the MU is configured to generate the at least one group of APs by performing random grouping of the plurality of APs based on the plurality of capability information messages.

3. The DAS of claim 2, wherein the MU is configured to periodically perform regrouping of the randomly grouped APs based on one or more predefined factors to maximize rank indicator associated with the plurality of UEs, wherein a rank indicator comprises a number of independent antenna paths observed by a corresponding UE of the plurality of UEs, and wherein the one or more predefined factors comprise rank indicators associated with the plurality of UEs, signal qualities observed by the plurality' of UEs, interferences observed by the plurality of UEs. a number of UEs located within a particular region.

4. The DAS of claim 1, wherein to generate the at least one group of APs from the plurality of APs or to periodically perform regrouping of the randomly grouped APs, the MU is configured to: for each AP of the plurality of APs: configure the AP to transmit a known reference signal towards remaining APs of the plurality of APs; and receive measurements of at least one parameter from each of the remaining APs, wherein the measurements of the at least one parameter received from a particular AP of the remaining APs are indicative of proximity of the AP with the particular AP; based on the received measurements, generate a multi-dimensional matrix comprising the measurements indicative of proximity among different APs of the plurality of APs; and generate the at least one group of APs based on the proximity among the different APs of the plurality’ of APs.

5. The DAS of claim 4, wherein the multi-dimensional matrix comprises a precoding matrix, the MU is further configured to: configure one or more of the plurality of APs to process downlink signals, to be transmitted tow ards at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the at least one UE; and configure the one or more of the plurality’ of APs to process uplink signals, transmitted by the at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the one or more APs.

6. The DAS of claim 1, wherein the MU is further configured to: receive an uplink rank indicator message from each UE of the plurality' of UEs, wherein the rank indicator message indicates a number of independent antenna paths associated with the DAS which are observed by the UE; and schedule downlink transmission for the UE based on the number of independent antenna paths observed by the UE.

7. The DAS of claim 1, wherein the MU is further configured to: receive a capability request from the donor BS requesting capability information of the DAS; and in response to receiving the capability request from the donor BS, transmit a request to the plurality of APs for the plurality of capability information messages.

8. The DAS of claim 1, wherein the MU is configured to advertise each of the at least one group of APs as a single virtual AP (vAP) to create Massive MIMO effect.

9. The DAS of claim 1, wherein the DAS comprises a virtual DAS (vDAS) and the MU comprises a virtual MU (vMU), wherein the vDAS comprises at least one physical server computer configured to execute virtualization software that creates a virtualized environment, and wherein the at least one physical server computer is configured to instantiate and execute a set of one or more virtual network functions (VNFs) used to implement the vMU, and wherein the physical server computer is communicatively coupled to the plurality of APs using a fronthaul network.

10. A method of providing wireless communication using a Distributed Antenna System (DAS) that comprises a master unit (MU) communicatively coupled with a donor base station (BS), and a plurality of access points (APs) communicatively coupled with the MU and configured to wirelessly communicate with a plurality of user equipment (UEs) via a respective set of one or more coverage antennas, the method comprises: receiving a plurality of capability information messages from the plurality of APs, wherein each capability information message comprises information indicating at least a number of coverage antennas associated with a corresponding AP; generating at least one group of APs from the plurality of APs by processing the plurality of capability information messages; generating at least one combined capability information message corresponding to the at least one group of APs, wherein each combined capability information message comprises information indicating at least a number of coverage antennas associated w ith a corresponding group of APs: and transmitting the at least one combined capability information message to the donor BS for configuring Massive Multiple-Input-Multiple-Output (M-MIMO) operations of the donor BS.

11. The method of claim 10, wherein generating the at least one group of APs from the plurality of APs comprises generating the at least one group of APs by performing random grouping of the plurality of APs based on the plurality of capability information messages.

12. The method of claim 11, further comprising: periodically performing regrouping of the randomly grouped APs based on one or more predefined factors to maximize rank indicators associated with the plurality of UEs, wherein a rank indicator comprises a number of independent antenna paths observed by a corresponding UE of the plurality of UEs, and wherein the one or more predefined factors comprise rank indicators associated with the plurality of UEs, signal qualities observed by the plurality of UEs, interferences observed by the plurality of UEs, a number of UEs located within a particular region.

13. The method of claim 10, wherein generating the at least one group of APs from the plurality of APs or periodically performing the regrouping of the randomly grouped APs comprises: for each AP of the plurality of APs: configuring the AP to transmit a known reference signal towards remaining APs of the plurality of APs; and receiving measurements of at least one parameter from each of the remaining APs, wherein the measurements of the at least one parameter received from a particular AP of the remaining APs are indicative of proximity of the AP with the particular AP; based on the received measurements, generating a multi-dimensional matrix comprising the measurements indicative of proximity among different APs of the plurality of APs; and generating the at least one group of APs based on the proximity among the different APs of the plurality of APs.

14. The method of claim 13, wherein the multi-dimensional matrix comprises a precoding matrix, the method further comprises: configuring one or more of the plurality of APs to process downlink signals, to be transmitted towards at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the at least one UE; and configure the one or more of the plurality of APs to process uplink signals, transmitted by the at least one UE of the plurality of UEs, using the precoding matrix for maximizing received signal strength at the one or more APs.

15. The method of claim 10, further comprising: receiving an uplink rank indicator message from each UE of the plurality of UEs, wherein the rank indicator message indicates a number of independent antenna paths associated with the DAS which are observed by the UE; and scheduling downlink transmission for the UE based on the number of independent antenna paths observed by the UE.

16. The method of claim 10, further comprising: receiving a capability request from the donor BS requesting capability' information of the DAS; and in response to receiving the capability request from the donor BS. transmitting a request to the plurality of APs for the plurality' of capability information messages.

17. The method of claim 10, further comprising: advertising each of the at least one group of APs as a single virtual AP (vAP) to create Massive MIMO effect.

18. The method of claim 10, wherein the DAS comprises a virtual DAS (vDAS) and the MU comprises a virtual MU (vMU), wherein the vDAS comprises at least one physical server computer configured to execute virtualization software that creates a virtualized environment, and wherein the at least one physical server computer is configured to instantiate and execute a set of one or more virtual network functions (VNFs) used to implement the vMU, and wherein the physical server computer is communicatively coupled to the plurality of APs using a fronthaul network.