WO2023175374A1

WO2023175374A1 - Method to support larger arrays and inter-radio antenna calibration

Info

Publication number: WO2023175374A1
Application number: PCT/IB2022/052346
Authority: WO
Inventors: Shiguang Guo; Hai Wang
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2022-03-15
Filing date: 2022-03-15
Publication date: 2023-09-21
Anticipated expiration: 2024-09-15

Abstract

A method and network node for inter-radio antenna calibration between subarrays configured to form a larger array are disclosed. According to one aspect, a method in a network node includes providing at least two active antenna subsystems, each active antenna subsystem having an antenna array, the antenna arrays of any two selected active antenna subsystems being separated by a gap. Different options for inter-radio antenna calibrations are proposed for both coupler-less and coupler based approaches. The method also includes determining a phase correction to signals to be applied to each antenna array of the two selected active antenna subsystems to compensate for the gap between the antenna arrays. The method further includes configuring a beam former in at least one of the two selected active antenna subsystems to apply the phase corrections during operation of the active antenna system.

Description

METHOD TO SUPPORT LARGER ARRAYS AND INTER-RADIO

ANTENNA CALIBRATION

TECHNICAL FIELD

The present disclosure relates to wireless communications, and in particular, to arrangements for inter-radio antenna calibration between subarrays configured to form a larger array.

BACKGROUND

The Third Generation Partnership Project (3 GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs. Sixth Generation (6G) wireless communication systems are also under development.

Massive MIMO and Beamforming

Active antenna systems (AAS) are one of several key technologies adopted by 4G LTE and 5G NR to enhance the wireless network performance and capacity by using full dimension MIMO (FD-MIMO) or massive MIMO. A typical AAS system consists of two-dimensional antenna elements array with M rows, N columns and K polarizations (K=2 in case of cross-polarization) as shown in FIG. 1

The codebook-based precoding in AAS is based on a set of pre-defined precoding matrices. The precoding matrix indication (PMI) may be selected by the WD with downlink (DL) channel state information reference signals (CSI-RS), or by a radio base station such as eNB or gNB with uplink (UL) reference signals.

The precoding matrix, denoted as IE, may be described for a two-stage precoding structure as follows:

W = 14^1^2. The first stage of the precoding structure, i.e., W₁₇ may be described as a codebook, and consists essentially of a group of 2 dimensional grid-of-beams (GoB), which may be characterized as:

where w_h and w_v are precoding vectors selected from an over-sampled discrete Fourier transform (DFT) for horizontal direction and vertical direction, respectively, and may be expressed by:

where and O₂ are the over-sampling rate in vertical and horizontal directions, respectively.

The second stage of the precoding matrix, W₂ is used for beam selection within the group of 2D GoB as well as the associated co-phasing between two polarizations. is determined according to the WD precoder matrix indicator (PMI) report of il. W₂ is determined according to WD PMI report of i2 . The WD will feed back PMI to the network node ,e.g., gNB. The network node, e.g., gNB, will apply a corresponding precoder for the transmission after receiving the WD feedback. The indices il and il are the indices of a predefined codebook from which the network node, e.g., gNB, may determine a precoder matrix.

AAS with eCPRI

An Advanced Antenna System (AAS) integrates antenna, radio, and part of the baseband processing like beamforming into one unit. An AAS is also called an antenna integrated radio (AIR). As shown in FIG. 2, an AAS, or AIR, is also called an open radio access network (ORAN) compliant radio unit (O-RU). ORAN is explained below.

Baseband function Beamforming will be performed in AAS on different channels/signals, such as a physical downlink shared channel (PDSCH), CSI-RS, demodulation reference signal (DM-RS), etc. Antenna Calibration (AC) Purpose and Realization on AAS

One purpose of antenna calibration is to remove long term radio frequency (RF) phase differences between transmit (TX) paths caused by delay differences in the different signal paths and phase difference in mixers and filters, etc. Calibration enables massive MIMO and beam forming features, which rely on proper amplitude and phase aligned signals at the antenna. Delay or phase will change overtime mainly due to temperature changes. Compensation for the change in delay or phase may provide good performance of massive MIMO and beamforming.

FIG. 3 shows an example cross-polarization antenna configuration having two pairs of antennas. There are both phase error and delay error. Phase error on an antenna port i = {0,1, 2, 3} is represented by:

Ph_t = 2nft_t + 0_£

The is a delay difference between antenna ports for both polarizations A and B. Port 0 and 1 are for polarization A. Port 2 and 3 are for polarization B. Delay for each polarization is represented by:

t_B ⁼ G ^— G

The phase error difference between antenna ports for each polarization is:

The phase error difference between the two polarization is:

When there is no phase error between the two polarizations, most precoders are beam-aligned as shown in FIG. 4. When there is not equal phase difference, beam-aligned precoders become misaligned and calibration is needed as shown in FIG. 5.

Antenna calibration in a general context means aligning the radio chains, from digital baseband to antenna, in amplitude, delay and phase for all the antennas. The calibration function should compensate for delay and phase differences between any pair of antenna branches, originating from the entire transmitter chain. The amplitude alignment is taken care of by the normal output power control. An active antenna system (AAS) integrates radio unit (RU) and antenna unit (AU) with certain baseband (BB) capability. The AAS connects to a digital unit (DU) using a packet-based connection such as Ethernet. AAS and DU could be co-located or far away. Typically, there are two types of connections between DU and AAS, which are a control path and a data path. The control path delivers messages used for configuration. The data path delivers user traffic data. A block diagram of an example AC realization is shown in FIG. 6. A typical AC realization of an AAS and DU is illustrated in FIG. 7. As shown in FIG. 7, the AC scheduling is in the DU since scheduling is performed in the digital domain. The remainder of the AC components are in the AAS. The DU and AAS have an eCPRI connection.

There are two versions of AC measurement. One is coupler based. In this case, there is a coupler on each transmit antenna to tap off a small percentage of signal to loop back. In the second version, to conserve costs, there is no coupler. As shown in FIG. 8, the mutual coupling effect between antennas via transmitting and receiving over the air is used to derive phase info for antenna calibration.

Open RAN (ORAN)

Open RAN (ORAN) is an international collaboration to allow mobile operators to use O-DUs and O-RUs from different vendors. O-DU refers to an ORAN compatible DU. O-RU refers to an ORAN compatible radio such as an AAS. ORAN provides benefits for operators to deploy networks. One benefit is the possibility to optimize the cost structure by deploying a DU or an AAS from different vendors.

To enable utilization of an O-DU and an O-RU from different vendors, the interface between RU and AAS is standardized. AC operation is supported by the interface shown in FIG. 9. In general, the O-RU requests AC allowance (time and frequency resources on which AC measurements can be performed) from the O-DU. The scheduler of the O-DU provides the AC requested allowance to the O-RU.

Currently, an antenna array may have 32 transmit antennas and 32 receive antennas (32T32R) or 64 transmit antennas and 64 receive antennas (64T64R) with up to 192 antenna elements. Uarger antenna arrays with more antenna element such as 384 antenna elements are needed in certain deployment scenarios such as when uplink coverage is limited. However, designing and developing a larger antenna array with more antenna elements may be expensive. In addition, a deployment scenario might be limited compared to normal scenarios. Therefore, it might not be cost effective to develop a larger antenna array just for the limited use case.

SUMMARY

Some embodiments advantageously provide methods, systems, and apparatuses for arrangements for inter-radio antenna calibration between subarrays configured to form a larger array.

Some embodiments provide for creating larger antenna arrays by reusing existing smaller antenna arrays. Methods to compensate phase discontinuity due to physical gaps between arrays are provided.. Different methods to support antenna calibration beamforming are described.

• Some embodiments provide support for larger antenna arrays, which provides increased equivalent isotropic radiated power (EIRP) for extended coverage.

• Some embodiments enable reuse of existing smaller antenna array to build a larger antenna array.

• This is a cost-effective approach and can address limited deployment scenario.

• Some embodiments provide improved beamforming performance by compensating for the gap between adjacent radio antenna arrays used to form the larger array.

• Different antenna calibration methods are presented herein.

• Some embodiments may be applied in ORANs including an ORAN lower layer split.

According to one aspect, a method is provided for beamforming and antenna calibration of a virtual active antenna system, AAS, comprising at least two active antenna subsystems, each active antenna subsystem having an antenna array of antenna elements. The method includes: injecting a pilot signal into each of two selected active antenna subsystems of the at least two active antenna subsystems simultaneously; determining a phase difference associated with a physical gap between the antenna arrays of the two selected active antenna subsystems based at least in part on a response of the two selected active antenna subsystems to the injected pilot signal; and compensating for the phase difference by applying correction weights to signals applied to at least one of the antenna arrays of the two selected active antenna subsystems, the correction weights being based at least in part on the phase difference.

According to this aspect, in some embodiments, determining the phase difference includes coupling an output signal from a first one of the two selected active antenna subsystems to the second one of the two selected active antenna subsystems. In some embodiments, determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array of a first one of the two selected active antenna subsystems and an antenna element in a second antenna array of the second one of the two selected active antenna subsystems. In some embodiments, the method includes coupling a baseband unit of a first one of the two selected active antenna subsystems to an antenna array of the other of the two selected active antenna subsystems. In some embodiments, the method also includes synchronizing baseband units of each of the two selected active antenna subsystems.

According to another aspect, a virtual active antenna system, AAS, is provided. The system includes at least two active antenna subsystems, each active antenna subsystem having an antenna array of antenna elements; and processing circuitry in communication with the at least two active antenna subsystems, the processing circuitry configured to: inject a pilot signal into each of two selected active antenna subsystems of the at least two active antenna subsystems; determine a phase difference associated with a physical gap between the antenna arrays of the two selected active antenna subsystems based at least in part on a response of the two selected active antenna subsystems to the injected pilot signal; and compensate for the phase difference by applying a correction weights to signals applied to at least one of the antenna arrays of the two selected active antenna subsystems, the correction signal being based at least in part on the phase difference.

According to this aspect, in some embodiments, the phase difference includes coupling an output signal from a first one of the two selected active antenna subsystems to the second one of the two selected active antenna subsystem. In some embodiments, determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array of a first one of the two selected active antenna subsystems and an antenna element in a second antenna array of the second one of the two selected active antenna subsystems. In some embodiments, a first one of the two selected active antenna subsystems further includes a baseband unit coupled to an antenna array of the other one of the two selected active antenna subsystems. In some embodiments, each active antenna subsystem includes a baseband unit and the processing circuitry is further configured to synchronize the baseband units of the two selected active antenna subsystems.

According to yet another aspect, a method for creating a virtual active antenna system by combining two or more existing AAS, is provided. The method includes: providing at least two active antenna subsystems, each active antenna subsystem having an antenna array, the antenna arrays of any two selected active antenna subsystems being separated by a gap; determining a phase correction to signals to be applied to each antenna array of the two selected active antenna subsystems to compensate for the gap between the antenna arrays; and configuring a beam former in at least one of the two selected active antenna subsystems to apply the phase corrections during operation of the active antenna system.

According to this aspect, in some embodiments, determining the phase correction includes injecting a common pilot signal into each of the two selected active antenna subsystems and measuring a difference in responses to the injected common pilot signal by each of the two selected active antenna subsystems. In some embodiments, determining the phase correction includes coupling an output signal from a first one of the antenna elements of the two selected active antenna subsystems to the second one of the antenna elements of the two selected active antenna subsystems. In some embodiments, determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array of a first one of the two selected active antenna subsystems and an antenna element in a second antenna array of the second one of the two selected active antenna subsystems. In some embodiments, the method includes coupling a baseband unit of a first one of the two selected active antenna subsystems to an antenna array of the other of the two selected active antenna subsystems.

According to yet another aspect, a virtual active antenna system, AAS, includes: at least two active antenna subsystems, each active antenna subsystem having an antenna array, the antenna arrays of any two selected active antenna subsystems being separated by a gap; and processing circuitry in communication with the at least two active antenna subsystems, the processing circuitry configured to: determine a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems of the least two active antenna subsystems to compensate for the gap between the antenna arrays; and configure a beam former in at least one of the two selected active antenna subsystem to apply the phase corrections during operation of the active antenna system.

According to this aspect, in some embodiments, determining the phase correction includes injecting a common pilot signal into each of the two selected active antenna subsystems and measuring a difference in responses to the injected common pilot signal by each of the two selected active antenna subsystems. In some embodiments, determining the phase correction includes coupling an output signal from a first one of the two selected active antenna subsystems arrays to the other of the two selected active antenna subsystems. In some embodiments, determining the phase correction includes determining mutual coupling between an antenna element in a first antenna array of a first one of the two selected active antenna subsystems and an antenna element in a second antenna array of the second one of the two selected active antenna subsystems. In some embodiments, a first one of the two selected active antenna subsystems further includes a shared baseband unit coupled to an antenna array of the other one of the two selected active antenna subsystems.

According to another aspect, a computer readable non-transitory storage medium is provided. The medium is configured to store executable computer code that when executed by a processor, causes the processor to: determine a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems to compensate for the gap between the antenna arrays; and configure a beam former in at least one of the two selected active antenna subsystems to apply the phase corrections during operation of the active antenna system.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is illustrates an NxM cross polarized antenna array;

FIG. 2 is a block diagram of an AAS including O-RU;

FIG. 3 is a cross -polarized antenna configuration;

FIG. 4 illustrates beam forming when phase is aligned;

FIG. 5 illustrates beam forming when phase is not aligned;

FIG. 6 is a block diagram of an example for AC realization;

FIG. 7 is an example AC realization using a digital unit (DU) and an AAS;

FIG. 8 is illustrates AC using mutual coupling between an antenna elements in an antenna array;

FIG. 9 illustrates a functional split between an ORAN compliant radio unit (RU) and an ORAN compliant digital unit (DU);

FIG. 10 is a schematic diagram of an example network architecture illustrating a communication system connected via an intermediate network to a host computer according to the principles in the present disclosure;

FIG. 11 is a block diagram of a host computer communicating via a network node with a wireless device over an at least partially wireless connection according to some embodiments of the present disclosure;

FIG. 12 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for executing a client application at a wireless device according to some embodiments of the present disclosure;

FIG. 13 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a wireless device according to some embodiments of the present disclosure;

FIG. 14 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data from the wireless device at a host computer according to some embodiments of the present disclosure; FIG. 15 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a host computer according to some embodiments of the present disclosure;

FIG. 16 is a flowchart of an example process in a network node for arrangements for inter-radio antenna calibration between subarrays configured to form a larger array;

FIG. 17 is a flowchart of another example process in a network node for arrangements for inter-radio antenna calibration between subarrays configured to form a larger array;

FIG. 18 illustrates two existing active antenna systems (AAS) combined horizontally;

FIG. 19 illustrates two existing active antenna systems combined vertically;

FIG. 20 illustrates a 4x8 active antenna array by combining 4 subarrays;

FIG. 21 illustrates a uniform linear array;

FIG. 22 illustrates two uniform linear arrays place end to end and separated by a gap;

FIG. 23 illustrates an example of joint calibration of two AAS combined to form a larger, virtual active antenna array; and

FIG. 24 illustrates a virtual active antenna array that includes two active antenna array subsystems, one of the two active antenna subsystems operating as a master subsystem.

DETAILED DESCRIPTION

Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to arrangements for inter-radio antenna calibration between subarrays configured to form a larger array. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.

The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi- standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The WD herein can be any type of wireless device capable of communicating with a network node or another WD over radio signals, such as wireless device (WD). The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device, etc.

Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell/multicast Coordination Entity (MCE), IAB node, relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure. Note further, that functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and/or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Some embodiments provide arrangements for inter-radio antenna calibration between subarrays configured to form a larger array.

Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 10 a schematic diagram of a communication system 10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node 16. Note that although only two WDs 22 and three network nodes 16 are shown for convenience, the communication system may include many more WDs 22 and network nodes 16.

Also, it is contemplated that a WD 22 can be in simultaneous communication and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a WD 22 can have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, WD 22 can be in communication with an eNB for LTE/E-UTRAN and a gNB for NR/NG-RAN.

The communication system 10 may itself be connected to a host computer 24, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 24 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 26, 28 between the communication system 10 and the host computer 24 may extend directly from the core network 14 to the host computer 24 or may extend via an optional intermediate network 30. The intermediate network 30 may be one of, or a combination of more than one of, a public, private or hosted network. The intermediate network 30, if any, may be a backbone network or the Internet. In some embodiments, the intermediate network 30 may comprise two or more sub-networks (not shown).

The communication system of FIG. 10 as a whole enables connectivity between one of the connected WDs 22a, 22b and the host computer 24. The connectivity may be described as an over-the-top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and/or signaling via the OTT connection, using the access network 12, the core network 14, any intermediate network 30 and possible further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of routing of uplink and downlink communications. For example, a network node 16 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 24 to be forwarded (e.g., handed over) to a connected WD 22a. Similarly, the network node 16 need not be aware of the future routing of an outgoing uplink communication originating from the WD 22a towards the host computer 24.

A network node 16 is configured to include a phase correction unit 32 which is configured to determine a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems of the least two active antenna subsystems to compensate for the gap between the antenna arrays.

Example implementations, in accordance with an embodiment, of the WD 22, network node 16 and host computer 24 discussed in the preceding paragraphs will now be described with reference to FIG. 11. In a communication system 10, a host computer 24 comprises hardware (HW) 38 including a communication interface 40 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 10. The host computer 24 further comprises processing circuitry 42, which may have storage and/or processing capabilities. The processing circuitry 42 may include a processor 44 and memory 46. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 42 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 44 may be configured to access (e.g., write to and/or read from) memory 46, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read- Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Processing circuitry 42 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by host computer 24. Processor 44 corresponds to one or more processors 44 for performing host computer 24 functions described herein. The host computer 24 includes memory 46 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 48 and/or the host application 50 may include instructions that, when executed by the processor 44 and/or processing circuitry 42, causes the processor 44 and/or processing circuitry 42 to perform the processes described herein with respect to host computer 24. The instructions may be software associated with the host computer 24.

The software 48 may be executable by the processing circuitry 42. The software 48 includes a host application 50. The host application 50 may be operable to provide a service to a remote user, such as a WD 22 connecting via an OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the remote user, the host application 50 may provide user data which is transmitted using the OTT connection 52. The “user data” may be data and information described herein as implementing the described functionality. In one embodiment, the host computer 24 may be configured for providing control and functionality to a service provider and may be operated by the service provider or on behalf of the service provider. The processing circuitry 42 of the host computer 24 may enable the host computer 24 to observe, monitor, control, transmit to and/or receive from the network node 16 and or the wireless device 22.

The communication system 10 further includes a network node 16 provided in a communication system 10 and including hardware 58 enabling it to communicate with the host computer 24 and with the WD 22. The hardware 58 may include a communication interface 60 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 10, as well as a radio interface 62 for setting up and maintaining at least a wireless connection 63 with a WD 22 located in a coverage area 18 served by the network node 16. The radio interface 62 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The communication interface 60 may be configured to facilitate a connection 65 to the host computer 24. The connection 65 may be direct or it may pass through a core network 14 of the communication system 10 and/or through one or more intermediate networks 30 outside the communication system 10.

In the embodiment shown, the hardware 58 of the network node 16 further includes processing circuitry 68. The processing circuitry 68 may include a processor 70 and a memory 72. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 68 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 70 may be configured to access (e.g., write to and/or read from) the memory 72, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the network node 16 further has software 74 stored internally in, for example, memory 72, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 74 may be executable by the processing circuitry 68. The processing circuitry 68 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node 16. Processor 70 corresponds to one or more processors 70 for performing network node 16 functions described herein. The memory 72 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 74 may include instructions that, when executed by the processor 70 and/or processing circuitry 68, causes the processor 70 and/or processing circuitry 68 to perform the processes described herein with respect to network node 16. For example, processing circuitry 68 of the network node 16 may include a phase correction unit 32 which is configured to determine a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems of the least two active antenna subsystems to compensate for the gap between the antenna arrays.

The communication system 10 further includes the WD 22 already referred to. The WD 22 may have hardware 80 that may include a radio interface 82 configured to set up and maintain a wireless connection 63 with a network node 16 serving a coverage area 18 in which the WD 22 is currently located. The radio interface 82 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The hardware 80 of the WD 22 further includes processing circuitry 84. The processing circuitry 84 may include a processor 86 and memory 88. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 84 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 86 may be configured to access (e.g., write to and/or read from) memory 88, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the WD 22 may further comprise software 90, which is stored in, for example, memory 88 at the WD 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the WD 22. The software 90 may be executable by the processing circuitry 84. The software 90 may include a client application 92. The client application 92 may be operable to provide a service to a human or non-human user via the WD 22, with the support of the host computer 24. In the host computer 24, an executing host application 50 may communicate with the executing client application 92 via the OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the user, the client application 92 may receive request data from the host application 50 and provide user data in response to the request data. The OTT connection 52 may transfer both the request data and the user data. The client application 92 may interact with the user to generate the user data that it provides.

The processing circuitry 84 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD 22. The processor 86 corresponds to one or more processors 86 for performing WD 22 functions described herein. The WD 22 includes memory 88 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 90 and/or the client application 92 may include instructions that, when executed by the processor 86 and/or processing circuitry 84, causes the processor 86 and/or processing circuitry 84 to perform the processes described herein with respect to WD 22.

In some embodiments, the inner workings of the network node 16, WD 22, and host computer 24 may be as shown in FIG. 11 and independently, the surrounding network topology may be that of FIG. 10.

In FIG. 11, the OTT connection 52 has been drawn abstractly to illustrate the communication between the host computer 24 and the wireless device 22 via the network node 16, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the WD 22 or from the service provider operating the host computer 24, or both. While the OTT connection 52 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

The wireless connection 63 between the WD 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the WD 22 using the OTT connection 52, in which the wireless connection 63 may form the last segment. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc.

In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and WD 22, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 52 may be implemented in the software 48 of the host computer 24 or in the software 90 of the WD 22, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 52 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 48, 90 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 52 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the network node 16, and it may be unknown or imperceptible to the network node 16. Some such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary WD signaling facilitating the host computer’s 24 measurements of throughput, propagation times, latency and the like. In some embodiments, the measurements may be implemented in that the software 48, 90 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 52 while it monitors propagation times, errors, etc.

Thus, in some embodiments, the host computer 24 includes processing circuitry 42 configured to provide user data and a communication interface 40 that is configured to forward the user data to a cellular network for transmission to the WD 22. In some embodiments, the cellular network also includes the network node 16 with a radio interface 62. In some embodiments, the network node 16 is configured to, and/or the network node’s 16 processing circuitry 68 is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/ supporting/ending a transmission to the WD 22, and/or preparing/terminating/ maintaining/supporting/ending in receipt of a transmission from the WD 22.

In some embodiments, the host computer 24 includes processing circuitry 42 and a communication interface 40 that is configured to a communication interface 40 configured to receive user data originating from a transmission from a WD 22 to a network node 16. In some embodiments, the WD 22 is configured to, and/or comprises a radio interface 82 and/or processing circuitry 84 configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/ supporting/ending a transmission to the network node 16, and/or preparing/ terminating/ maintaining/ supporting/ending in receipt of a transmission from the network node 16.

Although FIGS. 10 and 11 show various “units” such as the phase correction unit 32 as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG. 12 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIGS. 10 and 11, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIG. 11. In a first step of the method, the host computer 24 provides user data (Block S100). In an optional substep of the first step, the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50 (Block S102). In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (Block S104). In an optional third step, the network node 16 transmits to the WD 22 the user data which was carried in the transmission that the host computer 24 initiated, in accordance with the teachings of the embodiments described throughout this disclosure (Block S106). In an optional fourth step, the WD 22 executes a client application, such as, for example, the client application 92, associated with the host application 50 executed by the host computer 24 (Block s 108).

FIG. 13 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 10, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 10 and 11. In a first step of the method, the host computer 24 provides user data (Block SI 10). In an optional substep (not shown) the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50. In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (Block S 112). The transmission may pass via the network node 16, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD 22 receives the user data carried in the transmission (Block S 114). FIG. 14 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 10, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 10 and 11. In an optional first step of the method, the WD 22 receives input data provided by the host computer 24 (Block S 116). In an optional substep of the first step, the WD 22 executes the client application 92, which provides the user data in reaction to the received input data provided by the host computer 24 (Block SI 18). Additionally or alternatively, in an optional second step, the WD 22 provides user data (Block S120). In an optional substep of the second step, the WD provides the user data by executing a client application, such as, for example, client application 92 (Block S122). In providing the user data, the executed client application 92 may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the WD 22 may initiate, in an optional third substep, transmission of the user data to the host computer 24 (Block S124). In a fourth step of the method, the host computer 24 receives the user data transmitted from the WD 22, in accordance with the teachings of the embodiments described throughout this disclosure (Block S126).

FIG. 15 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 10, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 10 and 11. In an optional first step of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 16 receives user data from the WD 22 (Block S128). In an optional second step, the network node 16 initiates transmission of the received user data to the host computer 24 (Block S130). In a third step, the host computer 24 receives the user data carried in the transmission initiated by the network node 16 (Block S132).

FIG. 16 is a flowchart of an example process in a network node 16 for arrangements for inter-radio antenna calibration between subarrays configured to form a larger array. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 68 (including the phase correction unit 32), processor 70, radio interface 62 and/or communication interface 60. Network node 16 such as via processing circuitry 68 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is configured to inject a pilot signal into each of two selected active antenna subsystems of the at least two active antenna subsystems (Block S134). The process also includes determining a phase difference associated with a physical gap between the antenna arrays of the two selected active antenna subsystems based at least in part on a response of the two selected active antenna subsystems to the injected pilot signal (Block S136). The process further includes compensating for the phase difference by applying a correction weights to signals applied to at least one of the antenna arrays of the two selected active antenna subsystems, the correction signal being based at least in part on the phase difference (Block S138).

In some embodiments, determining the phase difference includes coupling an output signal from a first one of the two selected active antenna subsystems to the second one of the two selected active antenna subsystems. In some embodiments, determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array of a first one of the two selected active antenna subsystems and an antenna element in a second antenna array of the second one of the two selected active antenna subsystems. In some embodiments, the method includes coupling a baseband unit of a first one of the two selected active antenna subsystems to an antenna array of the other of the two selected active antenna subsystems. In some embodiments, the method also includes synchronizing baseband units of each of the two selected active antenna subsystems.

FIG. 17 is a flowchart of an example process in a network node 16 for arrangements for inter-radio antenna calibration between subarrays configured to form a larger array. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 68 (including the phase correction unit 32), processor 70, radio interface 62 and/or communication interface 60. Network node 16 such as via processing circuitry 68 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is configured to provide at least two active antenna subsystems, each active antenna subsystem having an antenna array, the antenna arrays of any two selected active antenna subsystems being separated by a gap (Block S140). The process also includes determining a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems of the least two active antenna subsystems to compensate for the gap between the antenna arrays (Block S142). The process also includes configuring a beam former in at least one of the two selected active antenna subsystem to apply the phase corrections during operation of the active antenna system (Block S144).

In some embodiments, determining the phase correction includes injecting a common pilot signal into each of the two selected active antenna subsystems and measuring a difference in responses to the injected common pilot signal by each of the two selected active antenna subsystems. In some embodiments, determining the phase correction includes coupling an output signal from a first one of the antenna elements of the two selected active antenna subsystems to the second one of the antenna elements of the two selected active antenna subsystems. In some embodiments, determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array of a first one of the two selected active antenna subsystems and an antenna element in a second antenna array of the second one of the two selected active antenna subsystems. In some embodiments, the method also includes coupling a baseband unit of a first one of the two selected active antenna subsystems to an antenna array of the other of the two selected active antenna subsystems.

According to another aspect, a computer readable non-transitory storage medium, such as the memory 72 of the network node 16, is provided. The medium is configured to store executable computer code that when executed by a processor, such as the processor 70, causes the processor to: determine a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems to compensate for the gap between the antenna arrays; and configure a beam former in at least one of the two selected active antenna subsystems to apply the phase corrections during operation of the active antenna system.

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for inter-radio antenna calibration between subarrays configured to form a larger array.

As shown in FIG. 18-20, two existing AAS can be placed side by side, horizontally, vertically, or both horizontally and vertically. For example, as shown in FIG. 18, each AAS subarray 94 and 96 has a 4 by 2 subarray and may be combined to form a larger 8 by 2 array that includes subarrays 94 and 96. In FIG. 19, two AAS subarrays 94 and 96 are vertically stacked. This can form an AAS with a 4 by array of subarrays. As shown in FIG. 20, more existing AAS subarrays 94, 96, 98 and 100, can be stacked together both horizontally and vertically to form an even larger array.

Digital beamforming correction

As shown in FIG. 21, a uniform N-element array 102 will form a beam for a given direction 0. The element distance is d. The radiation for the direction of 0 can be derived from element pattern and array factor. The element pattern is decided by the antenna element. The array factor is independent from the element pattern and can be calculated by:

N p _ ’ j(n-l) 2ndsin0/A+8') n=l where, 8 is the electrical phase difference between two adjacent elements.

The AAS formed by two or more AAS subarrays, such as by subarrays 104 and 106 shown in FIG. 22, is referred to herein as a virtual active antenna system 64. As shown in FIG. 22, the distance between the two N-element array is dO 108, which might be different from d. In order to have an optimal beamforming, an additional weight vector W(n), may be applied to compensate for dO if it is different from d.

Joint Antenna calibration

To perform beamforming with the virtual array (formed by two AASs), phase alignment may be obtained between two arrays according to methods disclosed herein. Joint antenna calibration may be employed for each subarray of the larger AAS array. This may depend on information exchanges between the two AAS for both AC injection and capture. The following options are considered: Option 1 : This option does not employ a coupler to couple power from two arrays. Rather, the mutual coupling effect between the two AAS antenna arrays is employed. In this case, the transmit antenna and the receive antenna could reside in different AASs.

Option 2: This option employs a coupler 110 to couple power from two arrays to dedicated hardware 112 link to exchange the AC measurement data. In this case, common injection data is used for both AAS. This option is shown in FIG. 23.

Option 3: In either Option 1 and Option 2, the DU may be employed to exchange the AC measurement data via an evolved common public radio interface (eCPRI).

Implementation Aspects

FIG. 24 is a diagram of a virtual active antenna system 64. As shown in FIG. 24, a first AAS 1 114 can be the master AAS where the AC algorithm for performing adaptation to compensate for a gap between the two antenna subarrays may be located. Measurement data from both AAS 114 and 116 can be made available to a common base band unit 118 in signal communication with the AAS 114 and 116 through a dedicated BB-AAS link interface such as an eCPRI. This also applies to ORAN compliant baseband and AAS implementations. Some or all of the beamforming to be applied that compensates for the gap dO between the subarrays of the AAS 114 and 116 may be performed in the master AAS 114. In some embodiments, some beamforming may be performed by a common beamforming unit 120. In the example of FIG. 24, each of the AAS 114 and 116 may include certain AC blocks (units or components) that have functionality that may be performed by the processing circuitry 68, radio interface 62, including the virtual active antenna system 64, of the network node 16.

Antenna calibration may include a control unit 122, algorithm 124, scheduling unit 126, measurement unit 128, and compensation unit 130. In case of joint antenna calibration, some of these components of antenna calibration may be consolidated in one selected AAS subarray, for example, in AAS 114. Similarly, beamforming functions may also be consolidated in a selected AAS 114, 116, such as by one or both of beamforming units 132 and 134. Thus, an antenna calibration (AC) function may include components shown in FIG. 24: • AC control unit 122 may be configured to configure and coordinate AC for different components. Before AC actions, configurations may be ready for all components. The AC control unit 122 may configure and trigger AC measurements by AC measurement unit 128 for active carriers, and may also configure AC compensation by AC compensation unit 130 based on measurement results.

• An AC algorithm 124 (which may be located in the master AAS 114 or in the baseband unit 118) is configured to calculate compensation weights based on AC measurement data from the AC measurement unit 128. These weights will then be used by the AC compensation unit 130 to compensate for the gap between the two antenna arrays 66 of the respective AAS 114 and 116.

• AC scheduling unit 126 (which may be located in one of the AAS 114, 116 or in the common baseband unit 118) is configured to determine radio resources in the time and frequency domains to be used for AC measurements. The AC scheduling unit 136 may finely schedule AC measurement signals into specific parts of the traffic data pattern.

• The AC measurement unit 128 may inject and capture AC signals. For example, in the downlink, the AC measurement unit 128 may inject a signal which is predefined at baseband. At the antennas, there may be a coupler where the injected signal is tapped. The tapped signal may be looped back to the baseband unit 118 and sent to the AC algorithm 124 to calculate the compensation weights.

• The AC compensation unit 130 may compensate traffic data signals to eliminate measured calibration errors. The AC compensation unit 130 may be configured to apply the compensation weights in beamforming operations. The AC compensation unit 130 may include the phase correction unit 32, in some embodiments.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and/or functionality described herein may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

Abbreviations that may be used in the preceding description include:

AAS active antenna system

AC antenna calibration

AU antenna unit

BB baseband DU digital unit

O-DU ORAN DU

OLLS ORAN lower layer split ORAN open RAN O-RU ORAN RU

RAN Radio Access Network

RU radio unit

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.

Claims

What is claimed is:

1. A method for beamforming and antenna calibration of a virtual active antenna system, AAS (64), comprising at least two active antenna subsystems (114, 116), each active antenna subsystem (114, 116) having an antenna array (66) of antenna elements, the method comprising: injecting (S134) a common pilot signal into each of two selected active antenna subsystems (114, 116) of the at least two active antenna subsystems (114, 116) simultaneously; determining (S136) a phase difference associated with a physical gap between the antenna arrays of the two selected active antenna subsystems (114, 116) based at least in part on a response of the two selected active antenna subsystems (114, 116) to the injected common pilot signal; and compensating (S138) for the phase difference by applying correction weights to signals applied to at least one of the antenna arrays (66) of the two selected active antenna subsystems (114, 116), the correction weights being based at least in part on the phase difference.

2. The method of Claim 1, wherein determining the phase difference includes coupling an output signal from a first one of the two selected active antenna subsystems (114, 116) to the second one of the two selected active antenna subsystems (114, 116).

3. The method of Claim 1, wherein determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array (66) of a first one of the two selected active antenna subsystems (114, 116) and an antenna element in a second antenna array (66) of the second one of the two selected active antenna subsystems (114, 116).

4. The method of any of Claims 1-3, further comprising coupling a baseband unit (118) of a first one of the two selected active antenna subsystems (114, 116) to an antenna array(66) of the other of the two selected active antenna subsystems (114, 116).

5. The method of any of Claims 1-4, further comprising synchronizing baseband units of each of the two selected active antenna subsystems (114, 116).

6. A virtual active antenna system (64), AAS, comprising: at least two active antenna subsystems (114, 116), each active antenna subsystem (114, 116) having an antenna array (66) of antenna elements; and processing circuitry (68) in communication with the at least two active antenna subsystems (114, 116), the processing circuitry (68) configured to: inject a common pilot signal into each of two selected active antenna subsystems (114, 116) of the at least two active antenna subsystems (114, 116); determine a phase difference associated with a physical gap between the antenna arrays (66) of the two selected active antenna subsystems (114, 116) based at least in part on a response of the two selected active antenna subsystems (114, 116) to the injected common pilot signal; and compensate for the phase difference by applying a correction weights to signals applied to at least one of the antenna arrays (66) of the two selected active antenna subsystems (114, 116), the correction signal being based at least in part on the phase difference.

7. The AAS of Claim 6, wherein determining the phase difference includes coupling an output signal from a first one of the two selected active antenna subsystems (114, 116) to the second one of the two selected active antenna subsystem (114, 116).

8. The AAS of Claim 6, wherein determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array (66) of a first one of the two selected active antenna subsystems (114, 116) and an antenna element in a second antenna array (66) of the second one of the two selected active antenna subsystems (114, 116).

9. The AAS of any of Claims 6-8, wherein a first one of the two selected active antenna subsystems (114, 116) further includes a baseband unit (118) coupled to an antenna array (66) of the other one of the two selected active antenna subsystems (114, 116).

10. The AAS of any of Claims 6-9, wherein each active antenna subsystem (114, 116) includes a baseband unit (118) and the processing circuitry is further configured to synchronize the baseband units of the two selected active antenna subsystems (114, 116).

11. A method for creating a virtual active antenna system (64) by combining two or more existing AAS, the method comprising: providing (S140) at least two active antenna subsystems (114, 116), each active antenna subsystem (114, 116) having an antenna array (66), the antenna arrays of any two selected active antenna subsystems (114, 116) being separated by a gap; determining (S142) a phase correction to signals to be applied to each antenna array (66) of the two selected active antenna subsystems (114, 116) to compensate for the gap between the antenna arrays; and configuring (S144) a beam former in at least one of the two selected active antenna subsystems (114, 116) to apply the phase corrections during operation of the virtual active antenna system (64).

12. The method of Claim 11, wherein determining the phase correction includes injecting a common pilot signal into each of the two selected active antenna subsystems (114, 116) and measuring a difference in responses to the injected common pilot signal by each of the two selected active antenna subsystems (114, 116).

13. The method of Claim 11, wherein determining the phase correction includes coupling an output signal from a first one of the antenna elements of the two selected active antenna subsystems (114, 116) to the second one of the antenna elements of the two selected active antenna subsystems (114, 116).

14. The method of any of Claims 11-13, wherein determining the phase difference includes determining mutual coupling between an antenna element in a first antenna array (66) of a first one of the two selected active antenna subsystems (114, 116) and an antenna element in a second antenna array (66) of the second one of the two selected active antenna subsystems (114, 116).

15. The method of any of Claims 11-14, further comprising coupling a baseband unit (118) of a first one of the two selected active antenna subsystems (114, 116) to an antenna array (66) of the other of the two selected active antenna subsystems (114, 116).

16. A virtual active antenna system (64), AAS, comprising: at least two active antenna subsystems (114, 116), each active antenna subsystem (114, 116) having an antenna array (66), the antenna arrays (66) of any two selected active antenna subsystems (114, 116) being separated by a gap; processing circuitry in communication with the at least two active antenna subsystems (114, 116), the processing circuitry configured to: determine a phase correction to signals to be applied to each antenna array of two selected active antenna subsystems (114, 116) of the least two active antenna subsystems (114, 116) to compensate for the gap between the antenna arrays (66); and configure a beam former in at least one of the two selected active antenna subsystem (114, 116) to apply the phase corrections during operation of the virtual active antenna system (64).

17. The AAS of Claim 16, wherein determining the phase correction includes injecting a common pilot signal into each of the two selected active antenna subsystems (114, 116) and measuring a difference in responses to the injected common pilot signal by each of the two selected active antenna subsystems (114, 116).

18. The AAS of Claim 16, wherein determining the phase correction includes coupling an output signal from a first one of the two selected active antenna subsystems (114, 116) to the other of the two selected active antenna subsystems (114, 116).

19. The AAS of any of Claims 16-18, wherein determining the phase correction includes determining mutual coupling between an antenna element in a first antenna array (66) of a first one of the two selected active antenna subsystems (114, 116) and an antenna element in a second antenna array (66) of the second one of the two selected active antenna subsystems (114, 116).

20. The AAS of any of Claims 16-19, wherein a first one of the two selected active antenna subsystems (114, 116) further includes a shared baseband unit (118) coupled to an antenna array (66) of the other one of the two selected active antenna subsystems (114, 116).

21. A computer readable non-transitory storage medium configured to store executable computer code that when executed by a processor, causes the processor to: determine a phase correction to signals to be applied to each antenna array (66) of two selected active antenna subsystems (114, 116) to compensate for the gap between the antenna arrays; and configure a beam former in at least one of the two selected active antenna subsystems (114, 116) to apply the phase corrections during operation of an active antenna system.