WO2022141425A1

WO2022141425A1 - Information transmission by circle selection and detection in coaxial multi-circle orbital angular momentum (oam) communication system

Info

Publication number: WO2022141425A1
Application number: PCT/CN2020/142217
Authority: WO
Inventors: Min Huang; Chao Wei; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-07-07

Abstract

Aspects of the disclosure relate to wireless communication systems having coaxial multi-circle antennas that exploit an orbital angular momentum (OAM) property of electromagnetic radiation to multiplex and modulate signals. Based on information to be transmitted, a transmitting device may identify a set of coordinate pairs. Here, each coordinate pair indicates an antenna index and an OAM mode index. The transmitting device may then accordingly transmit, for each identified coordinate pair, a waveform utilizing the indexed antenna and the indexed OAM mode. The transmitted information can be recovered by identifying the set of coordinate pairs in the waveform and mapping to a predetermined codebook. Other aspects, embodiments, and features are also claimed and described.

Description

INFORMATION TRANSMISSION BY CIRCLE SELECTION AND DETECTION IN COAXIAL MULTI-CIRCLE ORBITAL ANGULAR MOMENTUM (OAM) COMMUNICATION SYSTEM

TECHNICAL FIELD

The technology discussed below relates generally to wireless communication systems, and more particularly, to modulation of transmission waveforms and multiplexing of data streams. Embodiments can provide and enable techniques for multiplexing and modulating transmissions by controlling orbital angular momentum (OAM) modes and coaxial uniform circular array (UCA) circles.

INTRODUCTION

In wireless communication, information is transmitted over electromagnetic radiation by modulating a carrier signal with one or more information signals. Many techniques for modulating a carrier signal are used in the art, including various analog and digital modulation techniques such as frequency modulation (FM) , amplitude modulation (AM) , phase-shift keying (PSK) , and quadrature amplitude modulation (QAM) , among numerous others. In a typical cellular wireless communication system, many such signals can be multiplexed (e.g., combined) onto a suitable carrier or band to enable simultaneous communication between multiple devices. Once again, many techniques for multiplexing and multiple access are used in the art, including frequency-division multiplexing (FDM) , time-division multiplexing (TDM) , and orthogonal frequency-division multiplexing (OFDM) , among many others.

As the demand for mobile broadband access continues to increase, research and development continue to advance wireless communication technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

BRIEF SUMMARY OF SOME EXAMPLES

The following presents a simplified summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

In some aspects, the present disclosure provides an apparatus configured for wireless communication, including a processor, a plurality of antennas, a transceiver coupled to the processor and to plurality of antennas, and a memory coupled to the processor. Here, the processor and the memory are configured for receiving an information stream including a sequence of bits, and identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of the plurality of antennas, and an orbital angular momentum (OAM) mode index. The processor and the memory are further configured for transmitting via the transceiver, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.

In further aspects, the present disclosure provides an apparatus configured for wireless communication, including a processor, a plurality of antennas, a transceiver coupled to the processor and to plurality of antennas, and a memory coupled to the processor. Here, the processor and the memory are configured for receiving, via the transceiver, a waveform and identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform. The processor and the memory are further configured for recovering an information message from the received waveform based on the identified antenna index and OAM mode index.

In further aspects, the present disclosure provides a method of wireless communication that includes receiving an information stream including a sequence of bits, and identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of a plurality of antennas, and an orbital angular momentum (OAM) mode index. The method further includes transmitting, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.

In further aspects, the present disclosure provides a method of wireless communication that includes receiving a waveform and identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform. The method further includes recovering an information message from the received waveform based on the identified antenna index and OAM mode index.

In further aspects, the present disclosure provides an apparatus for wireless communication including means for receiving an information stream comprising a sequence of bits, means for identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of a plurality of antennas, and an orbital angular momentum (OAM) mode index, and means for transmitting, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.

In further aspects, the present disclosure provides an apparatus for wireless communication that includes means for receiving a waveform, means for identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform, and means for recovering an information message from the received waveform based on the identified antenna index and OAM mode index.

In further aspects, the present disclosure provides a non-transitory computer-readable medium storing computer-executable code that includes instructions for causing a transmitting device to receive an information stream including a sequence of bits, to identify a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of a plurality of antennas, and an orbital angular momentum (OAM) mode index, and to transmit, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.

In further aspects, the present disclosure provides a non-transitory computer-readable medium storing computer-executable code that includes instructions for causing a receiving device to receive a waveform, to identify an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform, and to recover an information message from the received waveform based on the identified antenna index and OAM mode index.

These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and embodiments will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments in conjunction with the accompanying figures. While the following description may discuss various advantages and features relative to certain embodiments and figures, all embodiments can include one or more of the advantageous features discussed herein. In other words, while this description may discuss one or more embodiments as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments discussed herein. In similar fashion, while this description may discuss exemplary embodiments as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a radio access network according to some aspects of this disclosure.

FIG. 2 is a schematic illustration of wireless communication between multi-antenna devices according to some aspects of this disclosure.

FIG. 3 is a block diagram conceptually illustrating an example of a hardware implementation for a transmitting device according to some aspects of the disclosure.

FIG. 4 is a block diagram conceptually illustrating an example of a hardware implementation for a receiving device according to some aspects of the disclosure.

FIG. 5 is a schematic illustration of wireless communication via a spiral phase plate (SPP) configuration that supports the use of orbital angular momentum (OAM) modes for multiplexing communications in accordance with some aspects of this disclosure.

FIG. 6 is a schematic illustration of wireless communication via a uniform circular array (UCA) configuration that supports the use of orbital angular momentum (OAM) modes for multiplexing communications in accordance with some aspects of this disclosure.

FIG. 7 is a schematic illustration of a coaxial multi-circle OAM configuration that supports two-dimensional index modulation according to some aspects of this disclosure.

FIG. 8 is a call flow diagram illustrating an exemplary process for channel modeling in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

FIG. 9 is a call flow diagram illustrating an exemplary process for one-dimensional index modulation in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

FIG. 10 provides tables illustrating some examples of one-dimensional index modulation in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

FIG. 11 is a call flow diagram illustrating an exemplary process for two-dimensional index modulation in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

FIG. 12 provides tables illustrating some examples of two-dimensional index modulation in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

FIG. 13 is a call flow diagram illustrating an exemplary process for wireless communication in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

FIG. 14 provides a table illustrating an example of capability limitation signaling in a coaxial multi-circle OAM communication system in accordance with some aspects of this disclosure.

DETAILED DESCRIPTION

In some aspects, this disclosure provides for a wireless communication technique that exploits an orbital angular momentum (OAM) property of electromagnetic (EM) waves for modulating a carrier to carry information, and/or for multiplexing information streams onto a common wireless resource. In particular, a coaxial multi-circle uniform circular array (UCA) -based antenna may be utilized in cooperation with dynamic OAM mode selection to provide a two-dimensional index modulation, such that information symbols and/or data streams or layers can be sent over a given wireless resource based on a transmitter circle index and an OAM mode index. Other aspects, embodiments, and features are also described and claimed.

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, those skilled in the art will readily recognize that these concepts may be practiced without these specific details. In some instances, this description provides well known structures and components in block diagram form in order to avoid obscuring such concepts.

While this description describes aspects and embodiments by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, packaging arrangements. For example, embodiments and/or uses may come about via integrated chip embodiments and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, AI-enabled devices, etc. ) . While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described innovations may occur. Implementations may range a spectrum from chip-level or modular components to non-modular, non-chip-level implementations and further to aggregate, distributed, or OEM devices or systems incorporating one or more aspects of the described innovations. In some practical settings, devices incorporating described aspects and features may also necessarily include additional components and features for implementation and practice of claimed and described embodiments. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor (s) , interleaver, adders/summers, etc. ) . It is intended that innovations described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end-user devices, etc. of varying sizes, shapes and constitution.

In communication systems, modulation is a technique for systematically varying a carrier signal in such a way that the transmitted signal contains information. Many techniques for modulating a carrier signal are used in the art, including various analog and digital modulation techniques. Modern wireless communication devices often employ quadrature amplitude modulation (QAM) , where a pair of quadrature (orthogonal) carrier signals have their amplitudes controlled to represent a desired location in a complex plane (sometimes referred to as a Gauss plane) .

And relatedly, multiplexing and multiple access are techniques for enabling simultaneous communication of multiple signals and/or devices on the same channel. For example, 5G New Radio (NR) specifications provide multiple access for uplink transmissions from mobile devices to base stations, and for multiplexing for downlink transmissions from base stations to mobile devices, utilizing orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) . In addition, for uplink transmissions, 5G NR specifications provide support for discrete Fourier transform-spread-OFDM (DFT-s-OFDM) with a CP (also referred to as single-carrier FDMA (SC-FDMA) ) . However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above schemes. For example, a mobile device may provide for uplink multiple access utilizing time division multiple access (TDMA) , code division multiple access (CDMA) , frequency division multiple access (FDMA) , sparse code multiple access (SCMA) , resource spread multiple access (RSMA) , orbital angular momentum (OAM) multiple access, coaxial multi-circle antenna multiple access, and/or other suitable multiple access schemes. Further, a base station 210 may multiplex DL transmissions to UEs 222 and 224 utilizing time division multiplexing (TDM) , code division multiplexing (CDM) , frequency division multiplexing (FDM) , orthogonal frequency division multiplexing (OFDM) , sparse code multiplexing (SCM) , orbital angular momentum (OAM) multiplexing, coaxial multi-circle antenna multiplexing, and/or other suitable multiplexing schemes.

OAM

An EM transmission can be characterized as a wave that carries momentum. In some examples, this momentum can include angular momentum, which includes a spin angular momentum (SAM) component, and an orbital angular momentum (OAM) component. In some cases, the SAM of the EM wave may be associated with the polarization of the EM wave. For example, an EM wave may be associated with different polarizations (e.g., circular polarization) , such as left and right. Accordingly, the SAM of an EM wave may have multiple (e.g., two) degrees of freedom.

In some cases, the OAM of the EM wave may be associated with a field spatial distribution of the EM wave, which may be in the form of a helical or twisted wavefront shape. For example, an EM wave or light beam may be in a helical mode, which may also be referred to as an OAM mode; and such helical mode may be characterized by a wavefront that is shaped as a helix with an optical vortex in the center (e.g., at the beam axis) , where each helical mode is associated with a different helical wavefront structure. The helical modes (e.g., OAM modes) may be defined or referred to by a mode index l, where a sign of the mode index l corresponds to a ‘handedness’ (e.g., left or right) of the helix or helices; and a magnitude of the mode index l (e.g., |l|) corresponds to a quantity of distinct but interleaved helices of the EM wave.

For example, for an EM wave associated with an OAM mode index of l = 0, the EM wave is not helical, and the wavefronts of the EM wave are multiple disconnected surfaces (e.g., the EM wave is a sequence of parallel planes) . For an EM wave associated with an OAM mode index of l = +1, the EM wave may propagate in a right-handed sense (e.g., has a right circular polarization or may be understood as having a clockwise circular polarization) and the wavefront of the EM wave may be shaped as a single helical surface with a step length equal to a wavelength λ of the EM wave. Likewise, the phase delay over one revolution of the EM wave may be equal to 2π. Similarly, for an OAM mode index of l = -1, the EM wave may propagate in a left-handed sense (e.g., has a left circular polarization or may be understood as having a counter-clockwise circular polarization) and the wavefront of the EM wave may be also be shaped as a single helical surface with a step length equal to the wavelength λ of the EM wave. Likewise, the phase delay over one revolution of the EM wave may be equal to -2π.

In a further example, for an OAM mode index of l = ±2, the EM wave may propagate in either a right-handed sense (if l = +2) or in a left-handed sense (if l = -2) and the wavefront of the EM wave may include two distinct but interleaved helical surfaces. In such examples, the step length of each helical surface may be equal to λ/2. Likewise, the phase delay over one revolution of the EM wave may be equal to ±4π. In general terms, a mode-l EM wave may propagate in either a right-handed sense or a left-handed sense (depending on the sign of l) and may include l distinct but interleaved helical surfaces with a step length of each helical surface equal to π/|l|. Likewise, the phase delay over one revolution of the EM wave may be equal to 2lπ. In some cases, an EM wave may be indefinitely extended to provide for a theoretically infinite number of degrees of freedom of the OAM of the EM wave (e.g.,

where

is the unbounded set of integers) . As such, the OAM of the EM wave may be associated with an infinite number of degrees of freedom.

OAM modulation

In some examples, the OAM mode index l of an EM wave may correspond to or otherwise function as (e.g., be defined as) an additional dimension for signal or channel multiplexing. For example, each OAM mode or state (of which there may be an infinite number) may function similarly (or equivalently) to a communication channel, such as a sub-channel. In other words, an OAM mode or state may correspond to a communication channel, and vice–versa. For instance, a transmitting device or a receiving device may communicate separate signals using EM waves having different OAM modes or states similar to how a transmitting device or receiving device may communicate separate signals over different communication channels. In some aspects, such use of the OAM modes or states of an EM wave to carry different signals may be referred to as the use of OAM beams.

Additionally, in some examples, EM waves with different OAM modes (e.g., OAM states) may be mutually orthogonal to each other (e.g., in a Hilbert sense, in which a space may include an infinite set of axes and sequences may be come infinite by way of always having another coordinate direction in which next elements of the sequence can go) . Likewise, in a Hilbert sense, orthogonal OAM modes or states may correspond to orthogonal communication channels (e.g., orthogonal sequences transmitted over a communication channel) and, based on the potentially infinite number of OAM modes or states, a wireless communication system employing the use of OAM beams may theoretically achieve infinite capacity. Here, due to the mutual orthogonality among OAM modes, the waveform of one OAM mode generally cannot be received by the receiver aperture configured for a different OAM mode. In theory, an infinite number of OAM states or modes may be twisted together for multiplexing, and the capacity of the OAM link can approach infinity while preserving orthogonality between signals carried by different OAM modes (e.g., indices l) . In practice, however, due to non-ideal factors (e.g., the Tx/Rx axial or position placement error, propagation divergence, and the like) , there may be crosstalk among OAM modes at the receiver, and thus a reduced number of concurrent OAM modes may be implemented between wireless devices. In some cases, a transmitting device may generate such OAM beams using spiral phase plate (SPP) or uniform circular array (UCA) configurations, such as discussed with reference to FIGs. 5 and 6.

The disclosure that follows presents various concepts that may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. FIG. 1 illustrates an example of a radio access network (RAN) 100 operating in a wireless communication system that supports one-and/or two-dimensional index modulation in connection with coaxial multi-circle OAM transmissions. By virtue of the wireless communication system 100, the UE 106 may be enabled to carry out data communication with an external data network 110, such as (but not limited to) the Internet.

The RAN 100 may implement any suitable wireless communication technology or technologies to provide radio access to one or more UEs. As one example, the RAN 100 may operate according to 3 ^rd Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN 104 may operate under a hybrid of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards, often referred to as LTE. The 3GPP refers to this hybrid RAN as a next-generation RAN, or NG-RAN. Of course, the RAN 100 may operate according to any suitable 6G or other technology, and many other examples may be utilized within the scope of the present disclosure.

In FIG. 1, two base stations 110 and 112 are shown in

cells

102 and 104; and a third base station 114 is shown controlling a remote radio head (RRH) 116 in cell 106. That is, a base station can have an integrated antenna or can be connected to an antenna or RRH by feeder cables. Broadly, a base station is a network element in a RAN responsible for radio transmission and reception in one or more cells to or from a UE. In different technologies, standards, or contexts, a base station may variously be referred to by those skilled in the art as a base transceiver station (BTS) , a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , an access point (AP) , a Node B (NB) , an eNode B (eNB) , a gNode B (gNB) , or some other suitable terminology.

The geographic area covered by the RAN 100 may be divided into cellular regions (cells) that can be uniquely identified by a user equipment (UE) based on an identification broadcasted from one access point or base station. FIG. 1 illustrates

macrocells

102, 104, and 106, and a small cell 108, each of which may include one or more sectors (not shown) . A sector is a sub-area of a cell. All sectors within one cell are served by the same base station. A radio link within a sector can be identified by a single logical identification belonging to that sector. In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell.

In the illustrated example, the

cells

102, 104, and 126 may be referred to as macrocells, as the

base stations

110, 112, and 114 support cells having a large size. Further, a base station 118 is shown in the small cell 108 (e.g., a microcell, picocell, femtocell, home base station, home Node B, home eNode B, etc. ) which may overlap with one or more macrocells. In this example, the cell 108 may be referred to as a small cell, as the base station 118 supports a cell having a relatively small size. Cell sizing can be done according to system design as well as component constraints.

It is to be understood that the RAN 100 may include any number of wireless base stations and cells. Further, a relay node may be deployed to extend the size or coverage area of a given cell. The

base stations

110, 112, 114, 118 provide wireless access points to a core network for any number of mobile apparatuses.

The RAN 100 supports wireless communication for multiple mobile apparatuses. A mobile apparatus may be referred to as user equipment (UE) in 3GPP standards, but may also be referred to by those skilled in the art as a mobile station (MS) , a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT) , a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE may be an apparatus (e.g., a mobile apparatus) that provides access to network services.

Within the present document, a “mobile” apparatus need not necessarily have a capability to move, and may be stationary. The term mobile apparatus or mobile device broadly refers to a diverse array of devices and technologies. UEs may include a number of hardware structural components sized, shaped, and arranged to help in communication; such components can include antennas, antenna arrays, RF chains, amplifiers, one or more processors, etc. electrically coupled to each other. For example, some non-limiting examples of a mobile apparatus include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal computer (PC) , a notebook, a netbook, a smartbook, a tablet, a personal digital assistant (PDA) , and a broad array of embedded systems, e.g., corresponding to an “Internet of things” (IoT) . A mobile apparatus may additionally be an automotive or other transportation vehicle, a remote sensor or actuator, a robot or robotics device, a satellite radio, a global positioning system (GPS) device, an object tracking device, a drone, a multi-copter, a quad-copter, a remote control device, a consumer and/or wearable device, such as eyewear, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player) , a camera, a game console, etc. A mobile apparatus may additionally be a digital home or smart home device such as a home audio, video, and/or multimedia device, an appliance, a vending machine, intelligent lighting, a home security system, a smart meter, etc. A mobile apparatus may additionally be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device controlling electric power (e.g., a smart grid) , lighting, water, etc. ; an industrial automation and enterprise device; a logistics controller; agricultural equipment; military defense equipment, vehicles, aircraft, ships, and weaponry, etc. Still further, a mobile apparatus may provide for connected medicine or telemedicine support, e.g., health care at a distance. Telehealth devices may include telehealth monitoring devices and telehealth administration devices, whose communication may be given preferential treatment or prioritized access over other types of information, e.g., in terms of prioritized access for transport of critical service data, and/or relevant QoS for transport of critical service data.

Wireless communication between a RAN 100 and a UE may be described as utilizing an air interface. The UEs and the base stations may wirelessly communicate with one another via one or more communication links utilizing one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication links. Transmissions over the air interface from a base station to one or more UEs may be referred to as downlink (DL) transmission. In accordance with certain aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at a scheduling entity (e.g., a base station) . Another way to describe this scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE to a base station may be referred to as uplink (UL) transmissions. In accordance with further aspects of the present disclosure, the term uplink may refer to a point-to-point transmission originating at a scheduled entity (e.g., a UE) .

In general, base stations may include a backhaul interface (not illustrated) for communication with a backhaul portion of the wireless communication system. The backhaul may provide a link between a base station and a core network. Further, in some examples, a backhaul network may provide interconnection between the respective base stations. Various types of backhaul interfaces may be employed, such as a direct physical connection, a virtual network, or the like using any suitable transport network.

In some examples, one or more base stations in the RAN 100 may be configured as integrated access and backhaul (IAB) nodes, where the wireless spectrum may be used both for access links (i.e., wireless links with UEs) , and for backhaul links. This scheme is sometimes referred to as wireless self-backhauling. By using wireless self-backhauling, rather than requiring each new base station deployment to be outfitted with its own hard- wired backhaul connection, the wireless spectrum utilized for communication between the base station and UE may be leveraged for backhaul communication, enabling fast and easy deployment of highly dense small cell networks.

FIG. 1 further includes a quadcopter or drone 120, which may be configured to function as a base station. That is, in some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station such as the quadcopter 120.

Each

base station

110, 112, 114, 118, and 120 may be configured to provide an access point to a core network for all the UEs in the respective cells. For example, UEs 122 and 124 may be in communication with base station 110;

UEs

126 and 128 may be in communication with base station 112;

UEs

130 and 132 may be in communication with base station 114 by way of RRH 116; UE 134 may be in communication with base station 118; and UE 136 may be in communication with mobile base station 120. In some examples, the

UEs

122, 124, 126, 128, 130, 132, 134, 136, 138, 140, and/or 142 may be the same as the UE/scheduled entity 106 described above and illustrated in FIG. 1.

In some examples, a mobile network node (e.g., quadcopter 120) may be configured to function as a UE. For example, the quadcopter 120 may operate within cell 102 by communicating with base station 110.

In a further aspect of the RAN 100, sidelink signals may be used between UEs without necessarily relying on scheduling or control information from a base station. For example, two or more UEs (e.g., UEs 126 and 128) may communicate with each other using peer to peer (P2P) or sidelink signals 127 without relaying that communication through a base station (e.g., base station 112) . In a further example, UE 138 is illustrated communicating with

UEs

140 and 142. Here, the UE 138 may function as a scheduling entity or a primary sidelink device, and

UEs

140 and 142 may function as a scheduled entity or a non-primary (e.g., secondary) sidelink device. In still another example, a UE may function as a scheduling entity in a device-to-device (D2D) , peer-to-peer (P2P) , or vehicle-to-vehicle (V2V) network, and/or in a mesh network. In a mesh network example,

UEs

140 and 142 may optionally communicate directly with one another in addition to communicating with the scheduling entity 138. Thus, in a wireless communication system with scheduled access to time–frequency resources and having a cellular configuration, a P2P configuration, or a mesh configuration, a scheduling entity and one or more scheduled entities may communicate utilizing the scheduled resources.

In some examples, The RAN 100 may operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band, in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band, or in even higher frequency bands reaching into the terahertz (THz) range. And in some examples, the RAN 100 may support millimeter wave (mmW) communications between the UEs and the base stations, and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some examples, this may facilitate use of antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

Multi-Antenna Arrays Generally

In some aspects of the disclosure, a wireless communication node or device may be configured with multiple antennas, e.g., for beamforming multiple-input multiple-output (MIMO) , and/or orbital angular momentum (OAM) modulation technology. FIG. 2 illustrates an example of wireless communication utilizing multiple antennas, supporting beamforming, MIMO, and OAM. In some examples, the system of FIG. 2 may implement aspects of RAN 100. The use of such multiple antenna technology enables a wireless communication system to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity.

Beamforming generally refers to directional signal transmission or reception. For a beamformed transmission, the amplitude and phase of each antenna in an array of antennas may be precoded, or controlled to create a desired (e.g., directional) pattern of constructive and destructive interference in the wavefront. In a MIMO system, a transmitter 202 includes multiple transmit antennas 204 (e.g., N transmit antennas) and a receiver 206 includes multiple receive antennas 208 (e.g., M receive antennas) . Thus, there are N × M signal paths 210 from the transmit antennas 204 to the receive antennas 208. Each of the transmitter 202 and the receiver 206 may be implemented, for example, within a scheduling entity 108, a scheduled entity 106, or any other suitable wireless communication device.

In a MIMO system, spatial multiplexing may be used to transmit multiple different streams of data, also referred to as layers, simultaneously on the same time-frequency resource. In some examples, transmitter may send multiple data streams to a single receiver. In this way, a MIMO system takes advantage of capacity gains and/or increased data rates associated with using multiple antennas in rich scattering environments where channel variations can be tracked. Here, the receiver may track these channel variations and provide corresponding feedback to the transmitter. In the simplest case, a rank-2 (i.e., including 2 data streams) spatial multiplexing transmission on a 2x2 MIMO antenna configuration will transmit two data streams via two transmit antennas 204. The signal from each transmit antenna 204 reaches each receive antenna 208 along a different signal path 210. The receiver 206 may then reconstruct the data streams using the received signals from each receive antenna 208.

The number of data streams or layers in a MIMO system corresponds to the rank of the transmission. In general, the rank of a MIMO system is limited by the number of transmit or receive

antennas

204 or 208, whichever is lower. In addition, the channel conditions at the receiving device, as well as other considerations, such as the available resources at the transmitting device, may also affect the transmission rank. For example, a base station in a cellular RAN may assign a rank (and therefore, a number of data streams) for a DL transmission to a particular UE based on a rank indicator (RI) the UE transmits to the base station. The UE may determine this RI based on the antenna configuration (e.g., the number of transmit and receive antennas) and a measured signal-to-interference-and-noise ratio (SINR) on each of the receive antennas. The RI may indicate, for example, the number of layers that may be supported under the current channel conditions. The base station may use the RI along with resource information (e.g., the available resources and amount of data to be scheduled for the UE) to assign a DL transmission rank to the UE.

The transmitting device determines the precoding of the transmitted data stream or streams based, e.g., on known channel state information of the channel on which the transmitting device transmits the data stream (s) . For example, the transmitting device may transmit one or more suitable reference signals (e.g., a channel state information reference signal, or CSI-RS) that the receiving device may measure. The receiver may then report measured channel quality information (CQI) back to the transmitting device. This CQI generally reports the current communication channel quality, and in some examples, a requested transport block size (TBS) for future transmissions to the receiver. In some examples, the receiver may further report a precoding matrix indicator (PMI) back to the transmitting device. This PMI generally reports the receiving device's preferred precoding matrix for the transmitting device to use, and may be indexed to a predefined codebook. The transmitting device may then utilize this CQI/PMI to determine a suitable precoding matrix for transmissions to the receiver.

In some cases, the RAN 100 may be an example of or otherwise support an OAM-based communication system and a transmitting device 202 or a receiving device 206 may communicate via OAM beams. In some examples, a transmitting device 202 or a receiving device 206 may generate and steer an OAM beam based on selecting a set of antenna elements from a planar array of antenna elements (e.g., a planar array on the transmitting device 202 or a receiving device 206 that may be used for MIMO communications) based on which antenna elements fall within a determined area on the planar array associated with a uniform circular array (UCA) for OAM communications. Additionally or alternatively, one or more transmitting devices 202 or receiving devices 206 may include components that provide for spiral phase plate (SPP) -based OAM communications.

In various examples, some or all of the wireless resources of the RAN 100 may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other resources of the RAN 100 may also carry pilots or reference signals. These pilots or reference signals may provide for a receiving device to perform channel estimation of the corresponding channel.

In a DL transmission, the transmitting device (e.g., a base station or scheduling entity) may allocate a set of wireless resources to carry DL control information including one or more DL control channels that generally carry information originating from higher layers to one or more receiving devices (e.g., a UE or scheduled entity) . In addition, DL resources may be allocated to carry DL physical signals that generally do not carry information originating from higher layers. These DL physical signals may include synchronization signals, demodulation reference signals (DM-RS) , phase-tracking reference signals (PT-RS) , channel-state information reference signals (CSI-RS) , etc.

In an UL transmission, a transmitting device (e.g., a UE or scheduled entity) may utilize a set of designated wireless resources to carry UL control information (UCI) to a receiving device (e.g., a base station or scheduling entity) . The UCI can originate from higher layers via one or more UL control channels. Further, UL wireless resources may carry UL physical signals that generally do not carry information originating from higher layers, such as demodulation reference signals (DM-RS) , phase-tracking reference signals (PT-RS) , sounding reference signals (SRS) , etc.

In addition to control information, wireless resources may be allocated for user data or traffic data, which may be carried on one or more traffic channels.

Block Diagrams

FIG. 3 is a block diagram illustrating an example of a hardware implementation for a transmitting device 300 employing a processing system 314. For example, the transmitting device 300 may be a user equipment (UE) , a base station, or any other wireless communication node, e.g., as illustrated in any of FIGs. 1 and/or 2.

The transmitting device 300 may be implemented with a processing system 314 that includes one or more processors 304. Examples of processors 304 include microprocessors, microcontrollers, digital signal processors (DSPs) , field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. In various examples, the scheduling entity 300 may be configured to perform any one or more of the functions described herein. That is, the processor 304, as utilized in a transmitting device 300, may be configured (e.g., in coordination with the memory 305) to implement any one or more of the processes and procedures described below and illustrated in FIGs. 8, 9, 11, and/or 13.

In this example, the processing system 314 may be implemented with a bus architecture, represented generally by the bus 302. The bus 302 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 314 and the overall design constraints. The bus 302 communicatively couples together various circuits including one or more processors (represented generally by the processor 304) , a memory 305, and computer-readable media (represented generally by the computer-readable medium 306) . The bus 302 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface 308 provides an interface between the bus 302 and a transceiver 310.

The transceiver 310 provides a communication interface or means for communicating with various other apparatus over a transmission medium. In some aspects, the transceiver 310 includes (or is coupled to) a plurality of antennas 311. The plurality of antennas 311 may be configured similar to the spiral phase plate (SPP) antennas described below and illustrated in FIG. 5; similar to the uniform circular array (UCA) antennas described below and illustrated in FIG. 6; similar to the coaxial multi-circle UCA configuration described below and illustrated in FIG. 7; or some combination of two or more of the above.

Depending upon the nature of the transmitting device 300, a user interface 312 (e.g., keypad, display, speaker, microphone, joystick) may also be provided. Of course, such a user interface 312 is optional, and may be omitted in some examples, such as a base station.

In some aspects of the disclosure, the processor 304 may include communication circuitry 341 configured (e.g., in coordination with the memory 305) for various functions, including, e.g., receiving an information stream (e.g., a sequence of bits) for transmission, and coordinating with a transceiver controller circuit 342 and/or transceiver controller instructions 362 to transmit a suitable waveform. For example, the communication circuitry 341 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., blocks 802 and/or 808; in relation to FIG. 9, including, e.g., block 904; in relation to FIG. 12, including, e.g., block 1104; and/or in relation to FIG. 13, including, e.g.,

block

1302, 1308, and/or 1312.

In some further aspects of the disclosure, the processor 304 may include a transceiver controller 342 configured (e.g., in coordination with the memory 305 and/or the transceiver 310) for various functions, including, e.g., transmitting a suitable waveform (e.g., information or data stream) and/or reference signal (e.g., DM-RS, CSI-RS, etc. ) as disclosed herein. For example, the transceiver controller 342 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., blocks 802 and/or 808; in relation to FIG. 9, including, e.g., block 904; in relation to FIG. 11, including, e.g., block 1104; and/or in relation to FIG. 13, including, e.g., blocks 1302, 1308, and/or 1312.

In some further aspects of the disclosure, the processor 304 may include coaxial multi-circle OAM modulating circuitry 343 configured (e.g., in coordination with the memory 305) for various functions, including, e.g., identifying a suitable coordinate pair (e.g., indicating an antenna index and an OAM mode index) based on a sequence of bits or an information stream. In some examples, the coaxial multi-circle OAM modulating circuitry 343 may jointly select an antenna index and an OAM mode index corresponding to a sequence of bits; and in some examples, the coaxial multi-circle OAM modulating circuitry 343 may, for each coordinate pair, select an OAM mode index, and then select an antenna index corresponding to a sequence of bits. In various examples, such two-dimensional index modulation and one-dimensional index modulation may be performed in coordination with the memory 305, which may store a codebook (e.g., a predetermined codebook) that maps coordinate pairs to corresponding bit sequences. For example, the coaxial multi-circle OAM modulating circuitry 343 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 808; in relation to FIG. 9, including, e.g., block 902; in relation to FIG. 11, including, e.g., block 1102; and/or in relation to FIG. 13, including, e.g., blocks 1312.

In some further aspects of the disclosure, the processor 304 may include receiving device configuration circuitry 344 configured (e.g., in coordination with the memory 305) for various functions, including, e.g., determining a suitable set of control information, configuration information, and/or capability limitation information to signal to a receiving device, e.g., for enabling the receiving device to receive a transmitted waveform and recover a transmitted information stream. For example, the receiving device configuration circuitry 344 may be configured to implement one or more of the functions described below in relation to FIG. 13, including, e.g.,

block

1302, 1306, and/or 1308.

The processor 304 is responsible for managing the bus 302 and general processing, including the execution of software stored on the computer-readable medium 306. The software, when executed by the processor 304, causes the processing system 314 to perform the various functions described below for any particular apparatus. The computer-readable medium 306 and the memory 305 may also be used for storing data that is manipulated by the processor 304 when executing software.

One or more processors 304 in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium 306. The computer-readable medium 306 may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip) , an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD) ) , a smart card, a flash memory device (e.g., a card, a stick, or a key drive) , a random access memory (RAM) , a read only memory (ROM) , a programmable ROM (PROM) , an erasable PROM (EPROM) , an electrically erasable PROM (EEPROM) , a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium 306 may reside in the processing system 314, external to the processing system 314, or distributed across multiple entities including the processing system 314. The computer-readable medium 306 may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

In one or more examples, the computer-readable storage medium 306 may store computer-executable code that includes communication instructions 361 that configure a transmitting device 300 for various functions, including, e.g., receiving an information stream (e.g., a sequence of bits) for transmission, and coordinating with a transceiver controller circuit 342 and/or transceiver controller instructions 362 to transmit a suitable waveform. For example, the communication instructions 361 may be configured to cause a transmitting device 300 to implement one or more of the functions described below in relation to FIG. 8, including, e.g., blocks 802 and/or 808; in relation to FIG. 9, including, e.g., block 904; in relation to FIG. 12, including, e.g., block 1104; and/or in relation to FIG. 13, including, e.g.,

block

1302, 1308, and/or 1312.

In one or more further examples, the computer-readable storage medium 306 may store computer-executable code that includes transceiver controller instructions 362 that configure a transmitting device 300 for various functions, including, e.g., transmitting a suitable waveform (e.g., information or data stream) and/or reference signal (e.g., DM-RS, CSI-RS, etc. ) as disclosed herein. For example, the transceiver controller instructions 362 may be configured to cause a transmitting device 300 to implement one or more of the functions described below in relation to FIG. 8, including, e.g., blocks 802 and/or 808; in relation to FIG. 9, including, e.g., block 904; in relation to FIG. 11, including, e.g., block 1104; and/or in relation to FIG. 13, including, e.g., blocks 1302, 1308, and/or 1312.

In one or more further examples, the computer-readable storage medium 306 may store computer-executable code that includes coaxial multi-circle OAM modulating instructions 363 that configure a transmitting device 300 for various functions, including, e.g., identifying a suitable coordinate pair (e.g., indicating an antenna index and an OAM mode index) based on a sequence of bits or an information stream. In some examples, the coaxial multi-circle OAM modulating instructions 363 may jointly select an antenna index and an OAM mode index corresponding to a sequence of bits; and in some examples, the coaxial multi-circle OAM modulating instructions 363 may, for each coordinate pair, select an OAM mode index, and then select an antenna index corresponding to a sequence of bits. In various examples, such two-dimensional index modulation and one-dimensional index modulation may be performed in coordination with the memory 305, which may store a codebook (e.g., a predetermined codebook) that maps coordinate pairs to corresponding bit sequences. For example, the coaxial multi-circle OAM modulating instructions 363 may be configured to cause a transmitting device 300 to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 808; in relation to FIG. 9, including, e.g., block 902; in relation to FIG. 11, including, e.g., block 1102; and/or in relation to FIG. 13, including, e.g., blocks 1312.

In one or more further examples, the computer-readable storage medium 306 may store computer-executable code that includes receiving device configuration instructions 364 that configure a transmitting device 300 for various functions, including, e.g., determining a suitable set of control information, configuration information, and/or capability limitation information to signal to a receiving device, e.g., for enabling the receiving device to receive a transmitted waveform and recover a transmitted information stream. For example, the receiving device configuration instructions 364 may be configured to cause a transmitting device 300 to implement one or more of the functions described below in relation to FIG. 13, including, e.g.,

block

1302, 1306, and/or 1308.

In one configuration, the transmitting device 300 for wireless communication includes means for receiving an information stream, means for identifying a set of coordinate pairs, means for transmitting a waveform, means for selecting an antenna index and an OAM mode index, means for transmitting a reference signal, and/or means for transmitting capability limitation information. In one aspect, the aforementioned means may be the processor 304 shown in FIG. 3 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means.

Of course, in the above examples, the circuitry included in the processor 304 is merely provided as an example, and other means for carrying out the described functions may be included within various aspects of the present disclosure, including but not limited to the instructions stored in the computer-readable storage medium 306, or any other suitable apparatus or means described in any one of the FIGs. 1, 2, 5, 6, and/or 7, and utilizing, for example, the processes and/or algorithms described herein in relation to FIGs. 8, 9, 11, and/or 13.

FIG. 4 is a conceptual diagram illustrating an example of a hardware implementation for an exemplary receiving device 400 employing a processing system 414. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system 414 that includes one or more processors 404. For example, the receiving device 400 may be a user equipment (UE) , a base station, or any other suitable wireless communication node, e.g., as illustrated in any of FIGs. 1 and/or 2.

In some aspects, the transceiver 410 includes (or is coupled to) a plurality of antennas 411. The plurality of antennas 411 may be configured similar to the spiral phase plate (SPP) antennas described below and illustrated in FIG. 5; similar to the uniform circular array (UCA) antennas described below and illustrated in FIG. 6; similar to the coaxial multi-circle UCA configuration described below and illustrated in FIG. 7; or some combination of two or more of the above.

The processing system 414 may be substantially the same as the processing system 314 illustrated in FIG. 3, including a bus interface 408, a bus 402, memory 405, a processor 404, and a computer-readable medium 406. Furthermore, the receiving device 400 may include a user interface 412 and a transceiver 410 substantially similar to those described above in FIG. 3. That is, the processor 404, as utilized in a receiving device 400, may be configured (e.g., in coordination with the memory 405) to implement any one or more of the processes described below and illustrated in FIGs. 8, 9, 11, and/or 13.

In some aspects of the disclosure, the processor 404 may include a transceiver controller 441 configured (e.g., in coordination with the memory 405) for various functions, including, for example, receiving and sampling a waveform (in some examples, including one or more reference signals) , and storing samples of the received waveform in memory 405. For example, the transceiver controller 441 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 806 and/or 812; in relation to FIG. 9, including, e.g., block 908; in relation to FIG. 11, including, e.g., block 1108; and/or in relation to FIG. 13, including, e.g., 1304, 1310, and/or 1314.

In some further aspects of the disclosure, the processor 404 may include a coaxial multi-circle OAM demodulating circuit 442 configured (e.g., in coordination with the memory 405) for various functions, including, for example, identifying an antenna index and/or an OAM mode index corresponding to a received waveform. For example, the coaxial multi-circle OAM demodulating circuit 442 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 814; in relation to FIG. 9, including, e.g., block 910; in relation to FIG. 11, including, e.g., 1110; and/or in relation to FIG. 13, including, e.g., block 1318.

In some further aspects of the disclosure, the processor 404 may include an information message recovery circuit 443 configured (e.g., in coordination with the memory 405) for various functions, including, for example, identifying a sequence of bits or information stream based on an identified coordinate pair corresponding to a received waveform. In some examples, such two-dimensional index demodulation and one-dimensional index demodulation may be performed in coordination with the memory 405, which may store a codebook (e.g., a predetermined codebook) that maps coordinate pairs to corresponding bit sequences. For example, the information message recovery circuit 443 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 814; in relation to FIG. 9, including, e.g., block 910; in relation to FIG. 11, including, e.g., 1110; and/or in relation to FIG. 13, including, e.g., block 1318.

In some further aspects of the disclosure, the processor 404 may include channel modeling circuitry 444 configured (e.g., in coordination with the memory 405) for various functions, including, for example, generating a channel estimate based on a received reference signal (e.g., DM-RS, CSI-RS, etc. ) , and in some examples, storing channel model information in memory 405. For example, the channel modeling circuitry 444 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 806 and/or 812; in relation to FIG. 9, including, e.g., block 908; in relation to FIG. 11, including, e.g., block 1108; and/or in relation to FIG. 13, including, e.g., block 1316.

And further, the computer-readable storage medium 406 may store computer-executable code that includes transceiver controller instructions 461 that configure a receiving device 400 for various functions, including, e.g., receiving and sampling a waveform (in some examples, including one or more reference signals) , and storing samples of the received waveform in memory 405. For example, the transceiver controller instructions 461 may be configured to cause a receiving device 400 to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 806 and/or 812; in relation to FIG. 9, including, e.g., block 908; in relation to FIG. 11, including, e.g., block 1108; and/or in relation to FIG. 13, including, e.g., 1304, 1310, and/or 1314.

In some further examples, the computer-readable storage medium 406 may store computer-executable code that includes coaxial multi-circle OAM demodulating instructions 462 that configure a receiving device 400 for various functions, including, e.g., identifying an antenna index and/or an OAM mode index corresponding to a received waveform. For example, the coaxial multi-circle OAM demodulating instructions 462 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 814; in relation to FIG. 9, including, e.g., block 910; in relation to FIG. 11, including, e.g., 1110; and/or in relation to FIG. 13, including, e.g., block 1318.

In some further examples, the computer-readable storage medium 406 may store computer-executable code that includes message recovery instructions 463 that configure a receiving device 400 for various functions, including, e.g., identifying a sequence of bits or information stream based on an identified coordinate pair corresponding to a received waveform. In some examples, such two-dimensional index demodulation and one-dimensional index demodulation may be performed in coordination with the memory 405, which may store a codebook (e.g., a predetermined codebook) that maps coordinate pairs to corresponding bit sequences. For example, the message recovery instructions 463 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 814; in relation to FIG. 9, including, e.g., block 910; in relation to FIG. 11, including, e.g., 1110; and/or in relation to FIG. 13, including, e.g., block 1318.

In some further examples, the computer-readable storage medium 406 may store computer-executable code that includes channel modeling instructions 464 that configure a receiving device 400 for various functions, including, e.g., generating a channel estimate based on a received reference signal (e.g., DM-RS, CSI-RS, etc. ) , and in some examples, storing channel model information in memory 405. For example, the channel modeling instructions 464 may be configured to implement one or more of the functions described below in relation to FIG. 8, including, e.g., block 806 and/or 812; in relation to FIG. 9, including, e.g., block 908; in relation to FIG. 11, including, e.g., block 1108; and/or in relation to FIG. 13, including, e.g., block 1316.

In one configuration, the receiving device 400 for wireless communication includes means for receiving a waveform and/or a reference signal, means for identifying an antenna index and an OAM mode index, means for recovering an information message, means for mapping a reference signal to a coordinate pair, means for generating channel model information, means for storing information in memory, and/or means for generating a channel response. In one aspect, the aforementioned means may be the processor 404 shown in FIG. 4 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means.

Of course, in the above examples, the circuitry included in the processor 304 is merely provided as an example, and other means for carrying out the described functions may be included within various aspects of the present disclosure, including but not limited to the instructions stored in the computer-readable storage medium 306, or any other suitable FIGs. 1, 2, 5, 6, and/or 7, and utilizing, for example, the processes and/or algorithms described herein in relation to FIGs. 8, 9, 11, and/or 13.

In some aspects, this disclosure provides for a wireless communication technique that exploits an orbital angular momentum (OAM) property of electromagnetic (EM) waves for modulating a carrier to carry information, and/or for multiplexing information streams onto a common wireless resource. Systems and devices that employ OAM are currently under intense development due to its improved communication spectrum efficiency, its capability to provide high-order spatial multiplexing (described further below) , potentially resulting in higher data rates, and the possibility to enable low receiver complexity, OAM is regarded as a strong candidate for future 6G communication technology or as an enhancement to existing 5G technology.

SPP Configuration

FIG. 5 illustrates an example of a spiral phase plate (SPP) OAM configuration that supports information transmission by OAM mode selection and detection in accordance with aspects of the present disclosure. In some examples, the illustrated SPP OAM configuration may implement aspects of RAN 100, and may be employed by the transmitting device 202/300 and receiving device 206/400. In this example, a transmitting device (e.g., UE or base station) may include transmitter OAM components 505 and a receiving device (e.g., UE or base station) may include receiver OAM components 510.

In cases in which the wireless devices use an SPP methodology, the transmitting device may convert an EM wave 515 associated with an OAM mode index l = 0 (e.g., a non-helical EM wave associated with mode-zero OAM) into an EM wave associated with an OAM mode index l ≠ 0 (e.g., a helical EM wave associated with a non-zero OAM mode) by passing the EM wave through an aperture 520 and an SPP 525. Such an SPP 525 may have a suitable structure and/or configuration, known to those skilled in the art, such as to generate an EM wave associated with a single OAM mode. Thus, the wireless device may use one SPP 525 to generate one OAM mode of an OAM beam 555. As such, a wireless device may implement a different SPP 525 for each OAM mode of an OAM beam 555.

In the example of FIG. 5, two OAM modes may be used (e.g., l = +1 and -1) . In the transmitter OAM components, a first EM wave 515-a may be provided to a first aperture 520-a and a first SPP 525-a, and a second EM wave 515-b may be provided to a second aperture 520-b and a second SPP 525-b. A beam splitter/combiner 550 may combine the output of the first SPP 525-a and the second SPP 525-b to generate OAM beam 555. The receiver OAM components 510 may receive the OAM beam 555 at a beam splitter/combiner 540 to provide instances of the OAM beam 555 to a third SPP 525-c and a fourth SPP 525-d that provide output to a first receiver aperture 520-c and a second receiver aperture 520-d, respectively. In general, a receiving device includes a separate SPP and receiver aperture for each OAM mode. Thus, the third SPP 525-c may be configured recover the OAM mode corresponding to the first SPP 525-a, and thus, the output of the first receiver aperture 520-c may correspond to the first EM wave 515-a (e.g., for OAM Mode l = 1) . Likewise, the fourth SPP 525-d may be configured to recover the OAM mode corresponding to the second SPP 525-b, and thus, the output of the second receiver aperture 520-d may correspond to the second EM wave 515-b (e.g., for OAM Mode l = 2) . In devices that use an SPP methodology, separate SPPs 525-a may thus be used for each OAM mode, and the number of SPPs 525 at a device may constrain the number of usable OAM modes. As discussed, wireless devices may also use a UCA methodology for OAM communications, an example of which is discussed with reference to FIG. 6.

UCA Configuration

FIG. 6 illustrates an example of a uniform circular array (UCA) OAM configuration that supports information transmission by OAM mode selection and detection in accordance with aspects of the present disclosure. In some examples, the illustrated UCA OAM configuration may implement aspects of RAN 100, and may be employed by the transmitting device 202/300 and receiving device 206/400. In this example, a transmitting device (e.g., UE or base station) may include OAM transmitter UCA antennas 605 and a receiving device (e.g., UE or base station) may include OAM receiver UCA antennas 610.

In some aspects, one or both of the OAM transmitter UCA antennas 605 or the OAM receiver UCA antennas 610 may be implemented as a planar array of antenna elements, which may be an example of or otherwise function as a (massive or holographic) MIMO array or an intelligent surface. In some cases, the transmitting device may identify a set of antenna elements 615 of the planar array that form a transmitter UCA, and a receiving device may identify a set of antenna elements 645 of the planar array that form a receiver UCA.

Upon selecting the set of antenna elements from the planar array, the OAM transmitter may apply a weight 635 to each of the selected antenna elements 615 based on the OAM mode index l of the transmitted OAM beam and one or more spatial parameters associated with each antenna element. In cases in which a UCA methodology is used to generate an OAM beam, the transmitting device may identify the set of antenna elements 615 on a circular array of antenna elements and may load a first set of weights 620 to each of the identified antenna elements based on a first OAM mode index (e.g., l = 0) . Further, for other OAM mode indices, other weights may be used for the set of antenna elements 615, such as a second OAM mode index (e.g., l = +1) that may use a second set of weights 625 and a third OAM mode index (e.g., l = –1) that may use a third set of weights 630.

For example, to generate an OAM beam with a selected OAM mode index (e.g., l = 0) , an OAM transmitter may load a weight 635 to each antenna element 615 on the UCA based on an angle 640 measured between a reference line on the UCA (e.g., the x-axis of the plane on which the UCA is located, where the origin is at the center of the UCA) and the antenna element, the OAM mode index l, and i (e.g., for complex-valued weights, which may alternatively be denoted as j in some cases) . In some cases, for instance, the weight for an antenna element n may be proportional to

where

is equal to the angle 640 measured between the reference line on the UCA and the antenna element n. By multiplying respective beamforming weights 635 of each set of weights 620–630 (e.g., for first set of weights 620, w ₁ = [w _1, 1, w _1, 2, …, w _1, 8] ^T) onto each antenna, a signal port may be generated. If the weight 635 of each antenna 615 is equal to

where

is the angle of antenna 615 in the circle (e.g., angle 640 for antenna element 615-g) , and l is the OAM mode index, then each set of weights 620–630 provides a beamformed port that is equivalent OAM mode l. By using different beamforming weights

where l’ ≠ l, multiple OAM modes are thus generated.

At the OAM receiver UCA antennas 610, the receiving device may have receive antenna elements 645 equipped in a circle. The channel matrix may be denoted from each transmit antenna to each receive antenna as H, and then for the beamformed channel matrix

any two columns of

are orthogonal, which means the beamformed ports have no crosstalk. This may allow OAM-based communication to realize high-level spatial multiplexing degree efficiently. Further, the eigen-based transmit precoding weights and receive combining weights of UCA-based OAM are constantly equal to a discrete Fourier transform (DFT) matrix, which is irrelevant to communication parameters (e.g., distance, aperture size, and carrier frequency) , and thus, UCA-based OAM may be implemented at relatively low cost. In some cases, the receiving device may test multiple different OAM modes to determine the OAM mode that was used in a transmission (e.g., based on whether a particular OAM mode yields a successfully demodulated transmission) , which may be used to identify one or more information bits of a transmission.

Multiple Coaxial UCA Configuration

FIG. 7 illustrates an example of a coaxial multi-circle UCA OAM configuration that supports multiplexing and modulating wireless transmissions by controlling OAM modes and coaxial UCA circles in accordance with aspects of the present disclosure. In some examples, the illustrated coaxial multi-circle UCA OAM configuration may implement aspects of RAN 100, and may be employed by the transmitting device 202/300 and receiving device 206/400. In this example, a transmitting device (e.g., UE or base station) may include OAM transmitter UCA antennas 705 and a receiving device (e.g., UE or base station) may include OAM receiver UCA antennas 710.

In some aspects, one or both of the OAM transmitter coaxial multi-circle UCA antennas 705 or the OAM receiver coaxial multi-circle UCA antennas 710 may be implemented as a planar array of coaxial UCA antenna elements as described above and illustrated in FIG. 6. In various examples, an OAM transmitter may include the same number of UCA circles as an OAM receiver, but this is not necessarily the case. That is, a transmitting device 202/300 can communicate with a receiving device 206/400 with the same number and with a different number of UCA circles.

According to a further aspect of the present disclosure, a transmitting device may employ a subset (e.g., one or more) of its UCA circles from its transmitter UCA antennas 705 for a given transmission. For example, a transmitting device may multiplex a plurality of beams, streams, or waveforms onto a given wireless resource by transmitting each such stream with a different respective set of one or more UCA circles. Theoretically, streams transmitted via different sets of UCA circles can be orthogonal, such that a receiving device can receive and separately recover these streams received over the same radio resource (e.g., overlapping in the time-and frequency-domains) .

In a further aspect, a transmitting device may independently select or control an OAM mode for each of the plurality of multiplexed OAM beams. That is, a transmitting device may utilize a first set of one or more UCA circles to transmit a first OAM beam having a first OAM mode, and a second set of one or more UCA circles to transmit a second OAM beam having a second OAM mode. Here, the first OAM mode (i.e., from the first set of one or more UCA circles) may be the same as, or different from the second OAM mode (i.e., from the second set of one or more UCA circles) . Various options and further details of such a system are provided in the discussion that follows.

A system that employs dynamic UCA circle index and OAM mode index selection as disclosed herein can provide for reduced system complexity and/or cost. For example, such a system enables a transmitting device to transmit information at a given data rate using a reduced number of simultaneously-transmitted data streams compared to another technique that utilizes all available UCA circles /OAM modes. In another example, such a system can increase the data rate compared to another technique that utilizes a fixed Tx circle index and OAM mode index selection.

In the discussion that follows, for ease of description, reference is made to a coaxial multi-circle UCA configuration such as the one illustrated in FIG. 7. However, it is to be understood that the present disclosure is not limited thereto. That is, according to another aspect of this disclosure, index modulation utilizing circle indices and OAM mode indices may be implemented utilizing an SPP configuration as described above and illustrated in FIG. 5. In such an SPP example, UCA circles of different sizes, and thus having different indices, may be provided by a transmitting device via the use of different apertures 520. And further, OAM modes may be provided by a transmitting device via the use of different SPPs 525. Here, one SPP may be employed to generate one OAM mode at one circle/aperture. Thus, for example, to configure a device to generate 4 circles, each of which can utilize 2 OAM modes, a transmitting device may include 8 apertures and 8 SPPs.

Channel Modeling

FIG. 8 is a call flow diagram illustrating an exemplary process for channel modeling in a coaxial multi-circle OAM communication system in accordance with some aspects of the present disclosure. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the process illustrated in FIG. 8 may be carried out by the transmitting device 300 illustrated in FIG. 3 and the receiving device 400 illustrated in FIG. 4. In some examples, the process of FIG. 8 may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

In some aspects of the disclosure, a transmitting device may provide for a receiving device to detect which UCA circle and/or which OAM mode is used for a given transmission by transmitting a suitable reference signal (e.g., a CSI-RS) . For example, a transmitting device may transmit a separate CSI-RS at different wireless resources (e.g., using different time-frequency resources and/or different sequences) for each combination of UCA circle and OAM mode.

In the description that follows, each UCA circle in a given coaxial multi-circle UCA antenna 705 is represented by a corresponding UCA circle index UCA _i., where i is an integer and 1 ≤ i ≤ N, and where N represents the total number of available UCA circles in the transmitter coaxial multi-circle UCA antenna array 705. Further, consistent with the above description, each OAM mode is represented by an OAM mode index l, where l is an integer and 1 ≤ l ≤ M, and where M represents the total number of used OAM modes. Thus, a combination of a selected UCA circle and OAM mode is indicated by its corresponding set of coordinates <UCA _i, l>. In various examples, the coordinates <UCA _i, l> can take any value corresponding to the full range of potential pairings of antenna index with OAM mode index.

A receiving device may then receive the respective CSI-RS transmissions utilizing its receiver coaxial multi-circle UCA antennas 710, and generate and store channel model information based on these reference signals. For example, for each set of coordinates <UCA _i, l>, a receiving device may estimate a channel response vector h _i, _l for each corresponding combination of UCA circle index UCA _i and OAM mode index l. The receiving device may accordingly store the estimated channel response vectors in memory.

In a subsequent transmission in a given time unit n (e.g., for transmission of an information stream, a signal, a symbol, etc. ) , the transmitting device may transmit a signal utilizing a selected set of coordinates <UCA _i, l>. In some aspects, the transmitted signal may include a DM-RS utilizing the selected set of coordinates <UCA _i, l>. In various examples, described further below, the DM-RS may constitute the transmitted signal, or may be included with or associated with a transmission of an information signal or symbol utilizing the same set of coordinates <UCA _i, l>. Based on the DM-RS, the receiving device may generate an estimate of the current channel response vector at time unit n, denoted

The receiving device can then determine which UCA circle and OAM mode were used for a received signal by comparing the estimated current channel response vector

with the stored channel response matrices h _i, l. For example, the receiving device may calculate the transmission parameters (e.g., the set of coordinates <UCA _i, l>) whose channel response vector h _i, l has the minimum distance with the estimated current channel response vector

For example, the receiving device may determine the set of coordinates <UCA _i, l> used for transmission of the received signal where <UCA _i, l> =

The receiving device may also determine the value of the OAM mode index in the coordinates <UCA _i, l> based on the received power. For example, a receiving device may determine in which OAM mode the received power at each UCA circle is the largest, considering that the signals of two different OAM modes are orthogonal.

Coaxial multi-circle UCA-based OAM

In some aspects, a receiving device may be enabled to uniquely identify and distinguish (or at least estimate) transmissions over the same wireless resources with any given (different) coordinates <UCA _i, l>. For example, a transmitting device may multiplex transmission streams utilizing two or more OAM modes, respectively, with each of the transmitter UCA circles 705 illustrated in FIG. 7. Thus, for a transmitter coaxial multi-circle UCA antenna 705 with N UCA circles, if each circle can independently transmit signals utilizing any of M OAM modes, then a transmitting device can theoretically multiplex up to N×M streams in this manner.

According to one aspect, two or more intra-circle (i.e., transmitted utilizing the same UCA circle) transmission streams made utilizing different OAM modes may be mutually orthogonal. And according to a further aspect, two or more inter-circle (i.e., transmitted utilizing different UCA circles) transmission streams made utilizing different OAM modes may be mutually orthogonal.

In some examples, two or more inter-circle transmission streams may be non-orthogonal when utilizing the same OAM mode. That is, for each OAM mode, there may exist inter-circle interference, which may cause difficulty for a receiving device to uniquely identify and distinguish two transmission streams made over the same wireless resources. Thus, a transmission stream from one UCA circle may mutually interfere with another transmission stream from a different circle if the two streams have the same OAM mode.

In some aspects, a receiving device may be configured for interference cancellation sufficient to distinguish inter-circle transmission streams made with the same OAM mode. However, the operations for performing interference cancellation of this nature may require the receiving device to perform high-dimensional matrix inversion or decomposition of received waveforms. As a result, if a transmitting device were to employ all its coaxial UCA circles to transmit signals, and all candidate OAM modes, this may lead to high-complexity processing at the receiving device. Furthermore, when the frequency spectrum and data rates are high, and they may be very high (e.g., on the order of 100 GHz and 1 Tbps) in some aspects of this disclosure, such high-complexity processing can become difficult at the receiving device.

Therefore, in a further aspect of this disclosure, a transmitting device may employ only a subset of its available UCA circles for transmitting a given information stream. In this way, the transmitting device can multiplex transmissions of information streams in such a way as to reduce or avoid such non-orthogonal transmissions.

Index Modulation in Coaxial Multi-Circle OAM Communication System

As discussed above, a transmitting device according to some aspects of this disclosure may be enabled to multiplex a plurality of information streams by applying different OAM modes to transmissions of their corresponding waveforms. Accordingly, an OAM mode index l can be considered to represent a degree of freedom. Similarly, a transmitting device according to some aspects of this disclosure may be enabled to multiplex a plurality of information streams by utilizing a different UCA circle for transmissions of their corresponding waveforms. Accordingly, a transmitter UCA circle index i can be considered to represent a second degree of freedom. Without constraints placed on such a transmitting device, it may accordingly be possible for the device to multiplex N×M streams on the same wireless resources.

Thus, according to an aspect of this disclosure, a transmitting device may employ two-dimensional index modulation (i.e., selection of a transmitter UCA circle index and an OAM mode index) to transmit a plurality of information streams in single-aperture multiple-circle (e.g., coaxial) OAM communication. In some examples, a transmitting device may transmit a plurality of corresponding waveforms utilizing any suitable modulation scheme, each one in association with a respective reference signal (e.g., DM-RS) . In this way, two-dimensional index modulation can be employed to provide a plurality (e.g., up to ×M ) of mutually orthogonal layers, ports, or channels for wireless communication. Another way to consider this scheme is that such two-dimensional index multiplexing can be employed to provide up to N×M additional bits of information to the transmission of an information symbol utilizing any suitable modulation scheme.

According to a further aspect of this disclosure, a transmitting device may employ two-dimensional index modulation (i.e., selection of a transmitter UCA circle index and an OAM mode index) to transmit information bits in a multiple-circle (e.g., coaxial) OAM communication. That is, as discussed above, in some examples, a transmitting device may omit a separate modulated waveform as described above, such that a reference signal (e.g., DM-RS) may constitute the transmitted signal at each set of coordinates. In this way, each reference signal transmission can represent an information symbol, with such information symbol representing up to N×M bits of information.

However, as discussed further below, in some aspects, a transmitting device may be configured to employ only a subset of its available UCA circles for transmitting an information stream. To compensate for the loss of its information-bearing capacity caused by the reduction in the available number of simultaneously used UCA circle, the present disclosure provides for a transmitting device to utilize part of the information bits to determine which UCA circle (s) are selected at each OAM mode. The receiving device can then retrieve these information bits by detecting which UCA circles are used for each OAM mode.

One-Dimensional Index Modulation

FIG. 9 is a call flow diagram illustrating an exemplary process for one-dimensional index modulation in a coaxial multi-circle OAM communication system in accordance with some aspects of the present disclosure. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the process of FIG. 9 may be carried out by the transmitting device 300 of FIG. 3 and/or the receiving device 400 of FIG. 4. In some examples, the process of FIG. 9 may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

That is, according to an aspect of this disclosure, a transmitting device configured for multi-circle OAM communication may employ one-dimensional index modulation to multiplex a plurality of transmissions. For example, for each of one or more OAM modes, a transmitting device may select a corresponding set of one or more UCA circles for a transmission representing a corresponding information symbol. as described below, by providing for a guaranteed or fixed number of transmitter UCA circles per OAM mode, the complexity needed for a receiving device to perform interference mitigation can be reduced compared to that which may be used for two-dimensional <UCA circle, OAM mode> index modulation.

At block 902, for each of one or more OAM modes, a transmitting device may select a suitable set of one or more UCA circles for a transmission of a set of information bits. In some examples, for each candidate OAM mode, a transmitting device may select any set of one or more of its UCA circles for transmission of a corresponding set of information bits. For example, referring now to FIG. 10, table 1002 shows the space of available coordinates <UCA _i, l> for an example where a transmitting device selects from among a set of 4 (four) UCA circles for a transmission at each of 2 (two) OAM modes. In this unrestricted example of one-dimensional index modulation, each of the eight (8) sets of coordinates can represent a different information symbol. Accordingly, if all transmitter UCA circles are utilized for each OAM mode, such an example with 2 OAM modes and 4 UCA circles can theoretically provide for up to 4×2=8 bits of information via one-dimensional index modulation.

However, as discussed above, in some aspects, a transmitting device may select only to utilize a subset of its available UCA circles for transmitting an information stream with a given OAM mode. That is, a transmitting device may designate a number of UCA circles that is smaller than its total number of available UCA circles, to be used for each OAM mode. In this manner, coordinates that might result in non-orthogonal transmissions can be reduced or avoided, and/or receiver complexity can potentially be reduced.

Clearly, such a constraint on a transmitting device may reduce the number of streams that it can multiplex or the number of information bits each symbol can represent. However, in a still further aspect of this disclosure, a transmitting device may exploit the property of intra-circle orthogonality to recover at least a portion of those lost bits of information. That is, each potential combination of the subset of UCA circles can represent information bits, such that a receiving device can receive information by virtue of detecting which combination of UCA circles were used per OAM mode.

For example, continuing with the example described above with a transmitting device having 4 (four) UCA circles and using 2 (two) OAM modes, the device may be restricted only to utilize a set of 2 (two) out of its 4 UCA circles for each OAM mode in a given symbol transmission. That is, in one illustrative example, a transmitting device may have a total number of available UCA circles N _all = 4, and may be restricted to utilizing a set of N _selected = 2 UCA circles per OAM mode. Referring once again to FIG. 10, table 1004 shows an example of the set of information bits that may be represented by utilizing this configuration.

As seen in table 1004, for each OAM mode, a transmitting device may multiplex transmissions utilizing various sets of two of the four UCA circles. If each UCA circle has an index {1, 2, 3, 4} , then the possible combinations the transmitting device can use include the following: 1&2; 1&3; 1&4; 2&3; 2&4; and 3&4. That is, this example provides for up to 6 different symbols per OAM mode based on UCA circle index pair selection. In table 1004, it is assumed that the information that the UCA circle combination per OAM mode represents is in a binary form. Thus, although there are potentially 6 different symbols represented per OAM mode, this falls between the range of different numbers that can be represented by 2 bits (4) and by 3 bits (8) . Thus, the illustrated example indicates that the selection of a UCA circle combination pair can provide 2 bits of information per OAM mode.

To generalize this example, it is seen that the number of ways that a transmitting device can select k UCA circles from among a set of n available UCA circles corresponds to a number of combinations characterized by the binomial coefficient

frequently called ‘n choose k’ and sometimes equivalently denoted

Thus, the number of different symbols that a transmitting device can orthogonally represent by selecting N _selected UCA circles from among a set of N _all available UCA circles corresponds to

And in an example where the information conveyed is directly representative of binary information bits, the capability of such a transmitting device to carry information bits per OAM mode via selection of UCA circle combinations is given as

Thus, at block 904, for each of a set of one or more OAM modes, a transmitting device may transmit a waveform 906 utilizing the corresponding selected set of one or more UCA circles. As described above, each transmission on a given UCA circle–OAM mode index coordinate <UCA _i, l> may simply be characterized as a DM-RS, such that the referenced transmission can convey

bits of information. However, in another example, each transmission on a given coordinate may be characterized as a DM-RS that is transmitted in association with (e.g., having any suitable property for enabling a receiving device to recognize the association, such as being at the same or nearby time) a modulated information waveform, which can potentially carry additional bits of information beyond those conveyed via UCA circle selection per OAM mode.

At block 908, a receiving device may receive the waveform 906 and detect the set of UCA circle indices for each OAM mode index utilized for transmission of the waveform 906. For example, as described above, the receiving device may reference stored channel model information, and based on its relationship with channel estimates based on the received waveform 906, identify the set of OAM mode indices and UCA circle indices utilized in the transmission.

At block 910, a receiving device may recover the transmitted information bits in the received waveform 906. For example, in a similar manner as that described above in relation to the table 1004, the transmitting device and receiving device may share a preconfigured or predetermined codebook that relates each set of selected UCA circles per OAM mode with a corresponding symbol or set of information bits. Thus, the receiving device may look up the set of information bits represented by the set of UCA circle–OAM mode index coordinates <UCA _i, l> detected in the received waveform 906.

FIG. 11 is a call flow diagram illustrating an exemplary process for two-dimensional index modulation in a coaxial multi-circle OAM communication system in accordance with further aspects of the present disclosure. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the process of FIG. 11 may be carried out by the transmitting device 300 of FIG. 3 and/or the receiving device 400 of FIG. 4. In some examples, the process of FIG. 11 may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

That is, according to an aspect of this disclosure, a transmitting device configured for multi-circle OAM communication may employ two-dimensional index modulation to multiplex a plurality of transmissions. For example, a transmitting device may generate an information symbol by jointly selecting a corresponding combination of UCA circle and OAM mode. In this manner, by jointly selecting sets of UCA circle–OAM mode index coordinates <UCA _i, l>, a transmitting device can achieve an increased data rate compared to that achievable utilizing one-dimensional UCA circle index modulation.

At block 1102, a transmitting device may select a set of UCA circle–OAM mode index coordinates <UCA _i, l> to represent a corresponding set of information bits. That is, the transmitting device may jointly select a transmitter UCA circle index and an OAM mode index to transmit a waveform that represents information bits for transmission. For example, referring now to FIG. 12, table 1202 shows the space of available coordinates <UCA _i, l> for an example where a transmitting device selects from among a combination of 4 (four) UCA circles and 2 (two) OAM modes for a transmission. In this unrestricted example of two-dimensional index modulation, each of the eight (8) sets of coordinates can represent a different information symbol. Accordingly, if all transmitter UCA circles are utilized for each OAM mode, such an example can theoretically provide for up to 4×2=8 bits of information via two-dimensional index modulation.

However, as discussed above, in some aspects, a transmitting device may select only to utilize a subset of its full range of available resources for transmitting an information stream. That is, a transmitting device may designate a candidate subset, including number of UCA circle–OAM mode index coordinates <UCA _i, l> that is smaller than its total number of available UCA circle–OAM mode index coordinates, to be used for each transmission. In this manner, coordinates that might result in non-orthogonal transmissions can be reduced and/or avoided, and/or receiver complexity can potentially be reduced.

For example, continuing with the example described above with a transmitting device having 4 (four) UCA circles and using 2 (two) OAM modes, the device may be restricted only to utilize a set of 4 (four) UCA circle–OAM mode index coordinates <UCA _i, l> for a given symbol transmission. That is, in one illustrative example, a transmitting device may have a total number N _all of eight (8) UCA circle–OAM mode index coordinates <UCA _i, l>, and may be restricted to utilizing a set of N _selected = four (4) such coordinates for a given symbol transmission. Referring once again to FIG. 12, table 1204 shows an example of the set of information bits that may be represented by utilizing this configuration.

As seen in table 1204, a transmitting device may multiplex transmissions utilizing various sets of four out of the eight available UCA circle–OAM mode index coordinates. For similar reasons as described above in relation to one-dimensional index modulation, the number of ways that a transmitting device can select N _selected coordinates from among a set of N _all available coordinates is characterized by the binomial coefficient

Thus, the presently-described example can provide for up to

different symbols per transmission based on the coordinates selection. Similar to the above example, the capability of a transmitting device to carry information bits per two-dimensional index transmission as described above is given as

Thus, the illustrated example indicates that the selection of a set of 4 out of 8 available coordinates per transmission can provide 6 bits of information per transmission.

Thus, at block 1104, a transmitting device may transmit a waveform 1106 utilizing the corresponding selected set of one UCA circle–OAM mode index coordinates. As described above, each transmission on a given UCA circle–OAM mode index coordinate <UCA _i, l> may simply be characterized as a DM-RS, such that the referenced transmission can convey

At block 1108, a receiving device may receive the waveform 1106 and detect the set of UCA circle–OAM mode index coordinates <UCA _i, l> utilized for transmission of the waveform 1106. For example, as described above, the receiving device may reference stored channel model information, and based on its relationship with channel estimates based on the received waveform 1106, identify the set of OAM mode indices and UCA circle indices utilized in the transmission.

At block 1110, a receiving device may recover the transmitted information bits in the received waveform 1106. For example, in a similar manner as that described above in relation to the table 1204, the transmitting device and receiving device may share a preconfigured or predetermined codebook that relates each set of coordinates with a corresponding symbol or set of information bits. Thus, the receiving device may look up the set of information bits represented by the set of UCA circle–OAM mode index coordinates <UCA _i, l> detected in the received waveform 1106.

FIG. 13 is a call flow diagram illustrating an exemplary process for index modulation in a coaxial multi-circle OAM communication system in accordance with further aspects of the present disclosure. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the process of FIG. 13 may be carried out by the transmitting device 300 of FIG. 3 and/or the receiving device 400 of FIG. 4. In some examples, the process of FIG. 13 may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

Although not illustrated in FIG. 13, the transmitting device and receiving device may be configured in any suitable fashion to share a common codebook that maps combinations of UCA circle–OAM mode index coordinates <UCA _i, l> to symbols, sequences, or sets of information bits. Configuration of the respective devices can be provided in any suitable manner, including but not limited to factory configuration, operator configuration, or codebook establishment between devices via suitable signaling and/or handshaking procedures. In some examples, such a codebook may include a two-dimensional table indicating a correspondence between a set of UCA circle index and OAM mode index combinations and a set of information bits.

At block 1302, a transmitting device may transmit a suitable set of configuration information 1304 to a receiving device. For example, a transmitting device may employ a transceiver to transmit one or more information elements to configure the receiving device for coaxial multi-circle OAM communication. Some examples of such information elements or configuration information are provided below, as illustrative examples.

For example, a transmitting device may provide a receiving device with a set of OAM modes that the transmitting device is using in connection with multi-circle OAM communication.

In a further example corresponding to one-dimensional index modulation, a transmitting device may provide a receiving device with a set of candidate transmitter UCA circles (e.g., where a set size is N _all = 4) and a number of simultaneously-used transmitter UCA circles to be used per OAM mode in a given transmission (e.g., where N _selected = 2) .

In a further example corresponding to two-dimensional index modulation, a transmitting device may provide a receiving device with a set of candidate UCA circle–OAM mode index coordinates <UCA _i, l> (e.g., where a set size is N _all = 8) and a number of simultaneously used coordinates (e.g., where a set size is N _selected = 4) .

At block 1306, a receiving device may select a suitable index modulation scheme for a given transmission based on a set of information for transmission (e.g., information bits received from any suitable information source, including but not limited to a higher-layer entity at the receiving device) .

At block 1308, a transmitting device may transmit a flag or other suitable indicator for indicating which index modulation scheme (e.g., a one-dimensional index modulation scheme or a two-dimensional index modulation scheme) is adopted for a transmission.

At block 1312, a transmitting device may select a set of transmitter UCA circles and OAM modes based on the information to be transmitted, and transmit a corresponding waveform to a receiving device. In some examples, the transmission of the flag indicating the modulation scheme may be provided together with the information-bearing waveform, although this is not necessarily the case and the respective transmissions may be made at any suitable time and in any suitable sequence.

At block 1316, a receiving device may detect the selected index modulation scheme, e.g., by receiving a corresponding flag or other suitable indication message 1310 from a transmitting device.

At block 1318, a receiving device may recover a set of transmitted information bits corresponding to the transmitted waveform. For example, the receiving device may employ procedures corresponding to FIG. 9 with one-dimensional index modulation, FIG. 11 with two-dimensional index modulation, etc.

Capability limitation signaling

According to a further aspect of this disclosure, a transmitting device may have functional or operational limitations for the number of OAM modes that a given transmitter UCA circle can multiplex in a given symbol or transmission. For example, referring to FIG. 14, consider a transmitting device with 4 UCA circles, and configured for up to 4 OAM modes. In a capability-limited transmitting device, transmissions might be limited to (for example) using at most 3 OAM modes per UCA circle. In this example, the transmitting device can remove or disallow any set (s) of candidate index pairs (denoted N _exception) that are beyond its capability limitation. In this example, the index pair selection may remove N _exception = 4 sets of candidate coordinate pairs: {1, 5, 9, 13} ; {2, 6, 10, 14} ; {3, 7, 11, 15} ; and {4, 8, 12, 16} , as indicated by the circled groups of four pairs in FIG. 14.

Thus, the number of bits of information that a coaxial multi-circle OAM communication system can multiplex with an index selection technique as disclosed herein becomes

In the example of FIG. 14, this results in

bits of information.

In some aspects, a transmitting device may transmit an indication of such a capability limitation to a receiving device to a receiving device. Any suitable format or mode for conveying this information may be utilized, including but not limited to signaling the maximum number of OAM modes allowed per UCA circle. In the above-described example, the transmitting device may transmit an indication of a parameter N _{max_modes_per_circle} = 3 to the receiving device. In some aspects, such capability limitation information may be included in the configuration information 1304 described above in relation to FIG. 13, or at any other suitable time.

Further Examples Having a Variety of Features:

Implementation examples are described in the following numbered clauses:

1. A method, apparatus, and non-transitory computer-readable medium for wireless communication, utilizing a processor, a plurality of antennas, a transceiver coupled to the processor and to plurality of antennas, and a memory coupled to the processor. The processor and the memory are configured for receiving an information stream comprising a sequence of bits, identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of the plurality of antennas, and an orbital angular momentum (OAM) mode index, and transmitting via the transceiver, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.

2. A method, apparatus, and non-transitory computer-readable medium of clause 1, wherein the plurality of antennas comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna corresponding to the antenna index comprises a UCA circle of the plurality of coaxial UCA circles.

3. A method, apparatus, and non-transitory computer-readable medium of any of clauses 1–2, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are configured, for each pair of the identified set of one or more coordinate pairs, for jointly selecting the antenna index and the OAM mode index corresponding to a portion of the sequence of bits.

4. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–3, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are further configured for selecting a plurality of coordinate pairs, comprising a subset out a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index.

5. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–4, wherein the processor and the memory, being configured for selecting the plurality of coordinate pairs, are further configured for referencing a predetermined codebook to identify the selected plurality of coordinate pairs based on the portion of the sequence of bits.

6. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–2, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are further configured, for each coordinate pair of the set of one or more coordinate pairs, for selecting the OAM mode index corresponding to the respective pair, and for selecting the antenna index corresponding to a portion of the sequence of bits.

7. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–2 and 6, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are further configured, for each OAM mode index of a full range of OAM mode indices, for selecting a plurality of antenna indices, comprising a subset out of a full set of potential antenna indices, the full set of potential antenna indices mapping to the plurality of antennas.

8. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–2 and 6–7, wherein the processor and the memory, being configured for selecting the plurality of antenna indices, are further configured for referencing a predetermined codebook to identify the selected plurality of antenna indices based on the portion of the sequence of bits.

9. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–8, wherein the processor and the memory are further configured for transmitting via the transceiver, for each respective coordinate pair of the set of one or more coordinate pairs of the transmitted waveform, a reference signal utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.

10. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–9, wherein the processor and the memory are further configured for, for each coordinate pair of a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index, transmitting a first reference signal utilizing the antenna corresponding to the antenna index and the OAM mode corresponding to the OAM mode index.

11. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–10, wherein the processor and the memory are further configured for transmitting, via the transceiver, configuration information comprising one or more of: a number of candidate OAM mode indices in a full range of OAM mode indices, a number of candidate antennas in the plurality of antennas, a number of antennas to be simultaneously used per OAM mode, a number of coordinate pairs in a full range of pairings of antenna index with OAM mode index, or a number of coordinate pairs to be simultaneously used.

12. The method, apparatus, and non-transitory computer-readable medium of any of clauses 1–11, wherein the processor and the memory are further configured for transmitting, via the transceiver, capability limitation information comprising one or more of: a set of disallowed candidate coordinate pairs, or a maximum number of OAM modes allowed per antenna.

13. A method, apparatus, and non-transitory computer-readable medium for wireless communication, utilizing a processor, a plurality of antennas, a transceiver coupled to the processor and to plurality of antennas, and a memory coupled to the processor. The processor and the memory are configured for receiving, via the transceiver, a waveform, identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform, and recovering an information message from the received waveform based on the identified antenna index and OAM mode index.

14. The method, apparatus, and non-transitory computer-readable medium of clause 13, wherein the processor and the memory are further configured for receiving, via the transceiver, one or more reference signals in association with the waveform.

15. The method, apparatus, and non-transitory computer-readable medium of any of clauses 13–14, wherein the plurality of antennas comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna index corresponds to a UCA circle of a plurality of coaxial UCA circles at a transmitting device.

16. The method, apparatus, and non-transitory computer-readable medium of any of clauses 13–15, wherein the processor and the memory are further configured for receiving, via the transceiver, a plurality of first reference signals; and, for each respective reference signal of the plurality of reference signals: mapping the respective reference signal to a corresponding coordinate pair indicating a candidate antenna index and a candidate orbital angular momentum (OAM) mode index, generating channel model information based on the respective reference signal, and storing the generated channel model information in memory in association with the corresponding coordinate pair.

17. The method, apparatus, and non-transitory computer-readable medium of any of clauses 13–16, wherein the processor and the memory, being configured for identifying the antenna index and the OAM mode index based on the reference signal, are further configured for generating a channel response corresponding to the waveform, and identifying the antenna index and the OAM mode index based on the stored generated channel model information.

Several aspects of a wireless communication network have been presented with reference to an exemplary implementation. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.

By way of example, various aspects may be implemented within other systems defined by 3GPP, such as Long-Term Evolution (LTE) , the Evolved Packet System (EPS) , the Universal Mobile Telecommunication System (UMTS) , and/or the Global System for Mobile (GSM) . Various aspects may also be extended to systems defined by the 3rd Generation Partnership Project 2 (3GPP2) , such as CDMA2000 and/or Evolution-Data Optimized (EV-DO) . Other examples may be implemented within systems employing IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Ultra-Wideband (UWB) , Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

Within the present disclosure, the word “exemplary” is used to mean “serving as an example, instance, or illustration. ” Any implementation or aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term “aspects” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C may still be considered coupled to one another-even if they do not directly physically touch each other. For instance, a first object may be coupled to a second object even though the first object is never directly physically in contact with the second object. The terms “circuit” and “circuitry” are used broadly, and intended to include both hardware implementations of electrical devices and conductors that, when connected and configured, enable the performance of the functions described in the present disclosure, without limitation as to the type of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, enable the performance of the functions described in the present disclosure.

One or more of the components, steps, features and/or functions illustrated in FIGs. 1–14 may be rearranged and/or combined into a single component, step, feature or function or embodied in several components, steps, or functions. Additional elements, components, steps, and/or functions may also be added without departing from novel features disclosed herein. The apparatus, devices, and/or components illustrated in FIGs. 1–14 may be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware.

It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one 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 and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

An apparatus configured for wireless communication, comprising:

a processor;

a plurality of antennas;

a transceiver coupled to the processor and to plurality of antennas; and

a memory coupled to the processor,

wherein the processor and the memory are configured for:

receiving an information stream comprising a sequence of bits;

identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of the plurality of antennas, and an orbital angular momentum (OAM) mode index; and

transmitting via the transceiver, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The apparatus of claim 1, wherein the plurality of antennas comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna corresponding to the antenna index comprises a UCA circle of the plurality of coaxial UCA circles.
The apparatus of claim 1, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are configured, for each pair of the identified set of one or more coordinate pairs, for jointly selecting the antenna index and the OAM mode index corresponding to a portion of the sequence of bits.
The apparatus of claim 3, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are further configured for:

selecting a plurality of coordinate pairs, comprising a subset out a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index.
The apparatus of claim 4, wherein the processor and the memory, being configured for selecting the plurality of coordinate pairs, are further configured for referencing a predetermined codebook to identify the selected plurality of coordinate pairs based on the portion of the sequence of bits.
The apparatus of claim 1, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are further configured, for each coordinate pair of the set of one or more coordinate pairs, for:

selecting the OAM mode index corresponding to the respective pair; and

selecting the antenna index corresponding to a portion of the sequence of bits.
The apparatus of claim 6, wherein the processor and the memory, being configured for identifying the set of one or more coordinate pairs, are further configured for:

for each OAM mode index of a full range of OAM mode indices, selecting a plurality of antenna indices, comprising a subset out of a full set of potential antenna indices, the full set of potential antenna indices mapping to the plurality of antennas.
The apparatus of claim 7, wherein the processor and the memory, being configured for selecting the plurality of antenna indices, are further configured for referencing a predetermined codebook to identify the selected plurality of antenna indices based on the portion of the sequence of bits.
The apparatus of claim 1, wherein the processor and the memory are further configured for:

transmitting via the transceiver, for each respective coordinate pair of the set of one or more coordinate pairs of the transmitted waveform, a reference signal utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The apparatus of claim 1, wherein the processor and the memory are further configured for:

for each coordinate pair of a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index, transmitting a first reference signal utilizing the antenna corresponding to the antenna index and the OAM mode corresponding to the OAM mode index.
The apparatus of claim 1, wherein the processor and the memory are further configured for transmitting, via the transceiver, configuration information comprising one or more of:

a number of candidate OAM mode indices in a full range of OAM mode indices;

a number of candidate antennas in the plurality of antennas;

a number of antennas to be simultaneously used per OAM mode;

a number of coordinate pairs in a full range of pairings of antenna index with OAM mode index; or

a number of coordinate pairs to be simultaneously used.
The apparatus of claim 1, wherein the processor and the memory are further configured for transmitting, via the transceiver, capability limitation information comprising one or more of:

a set of disallowed candidate coordinate pairs; or

a maximum number of OAM modes allowed per antenna.
An apparatus configured for wireless communication, comprising:

a processor;

a plurality of antennas;

a transceiver coupled to the processor and to plurality of antennas; and

a memory coupled to the processor,

wherein the processor and the memory are configured for:

receiving, via the transceiver, a waveform;

identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform; and

recovering an information message from the received waveform based on the identified antenna index and OAM mode index.
The apparatus of claim 13, wherein the processor and the memory are further configured for receiving, via the transceiver, one or more reference signals in association with the waveform.
The apparatus of claim 13, wherein the plurality of antennas comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna index corresponds to a UCA circle of a plurality of coaxial UCA circles at a transmitting device.
The apparatus of claim 13, wherein the processor and the memory are further configured for:

receiving, via the transceiver, a plurality of first reference signals; and

for each respective reference signal of the plurality of reference signals:

mapping the respective reference signal to a corresponding coordinate pair indicating a candidate antenna index and a candidate orbital angular momentum (OAM) mode index;

generating channel model information based on the respective reference signal; and

storing the generated channel model information in memory in association with the corresponding coordinate pair.
The apparatus of claim 16, wherein the processor and the memory, being configured for identifying the antenna index and the OAM mode index based on the reference signal, are further configured for:

generating a channel response corresponding to the waveform; and

identifying the antenna index and the OAM mode index based on the stored generated channel model information.
A method of wireless communication, comprising:

receiving an information stream comprising a sequence of bits;

identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of a plurality of antennas, and an orbital angular momentum (OAM) mode index; and

transmitting, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The method of claim 18, wherein the plurality of antennas comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna corresponding to the antenna index comprises a UCA circle of the plurality of coaxial UCA circles.
The method of claim 18, further comprising:

for each pair of the identified set of one or more coordinate pairs, jointly selecting the antenna index and the OAM mode index corresponding to a portion of the sequence of bits.
The method of claim 20, wherein the identifying the set of one or more coordinate pairs further comprises:

selecting a plurality of coordinate pairs, comprising a subset out a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index.
The method of claim 21, wherein the selecting the plurality of coordinate pairs further comprises:

referencing a predetermined codebook to identify the selected plurality of coordinate pairs based on the portion of the sequence of bits.
The method of claim 18, wherein the identifying the set of one or more coordinate pairs further comprises:

for each coordinate pair of the set of one or more coordinate pairs:

selecting the OAM mode index corresponding to the respective pair; and

selecting the antenna index corresponding to a portion of the sequence of bits.
The method of claim 23, wherein the identifying the set of one or more coordinate pairs further comprises:

for each OAM mode index of a full range of OAM mode indices, selecting a plurality of antenna indices, comprising a subset out of a full set of potential antenna indices, the full set of potential antenna indices mapping to the plurality of antennas.
The method of claim 24, wherein the selecting the plurality of antenna indices further comprises:

referencing a predetermined codebook to identify the selected plurality of antenna indices based on the portion of the sequence of bits.
The method of claim 18, further comprising:

transmitting, for each respective coordinate pair of the set of one or more coordinate pairs of the transmitted waveform, a reference signal utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The method of claim 18, further comprising:

for each coordinate pair of a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index, transmitting a first reference signal utilizing the antenna corresponding to the antenna index and the OAM mode corresponding to the OAM mode index.
The method of claim 18, further comprising transmitting configuration information comprising one or more of:

a number of candidate OAM mode indices in a full range of OAM mode indices;

a number of candidate antennas in the plurality of antennas;

a number of antennas to be simultaneously used per OAM mode;

a number of coordinate pairs in a full range of pairings of antenna index with OAM mode index; or

a number of coordinate pairs to be simultaneously used.
The method of claim 18, further comprising transmitting capability limitation information comprising one or more of:

a set of disallowed candidate coordinate pairs; or

a maximum number of OAM modes allowed per antenna.
A method of wireless communication, comprising:

receiving a waveform;

identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform; and

recovering an information message from the received waveform based on the identified antenna index and OAM mode index.
The method of claim 30, further comprising receiving one or more reference signals in association with the waveform.
The method of claim 30, wherein the plurality of antennas comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna index corresponds to a UCA circle of a plurality of coaxial UCA circles at a transmitting device.
The method of claim 30, further comprising:

receiving a plurality of first reference signals; and

for each respective reference signal of the plurality of reference signals:

mapping the respective reference signal to a corresponding coordinate pair indicating a candidate antenna index and a candidate orbital angular momentum (OAM) mode index;

generating channel model information based on the respective reference signal; and

storing the generated channel model information in memory in association with the corresponding coordinate pair.
The method of claim 33, wherein the identifying the antenna index and the OAM mode index based on the reference signal, further comprise:

generating a channel response corresponding to the waveform; and

identifying the antenna index and the OAM mode index based on the stored generated channel model information.
An apparatus for wireless communication, comprising:

means for receiving an information stream comprising a sequence of bits;

means for identifying a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of a plurality of antennas, and an orbital angular momentum (OAM) mode index; and

means for transmitting, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The apparatus of claim 35, wherein the means for transmitting comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna corresponding to the antenna index comprises a UCA circle of the plurality of coaxial UCA circles.
The apparatus of claim 35, further comprising:

means for, for each pair of the identified set of one or more coordinate pairs, jointly selecting the antenna index and the OAM mode index corresponding to a portion of the sequence of bits.
The apparatus of claim 37, wherein the means for identifying the set of one or more coordinate pairs is further configured for:

selecting a plurality of coordinate pairs, comprising a subset out a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index.
The apparatus of claim 38, wherein the means for selecting the plurality of coordinate pairs is further configured for:

referencing a predetermined codebook to identify the selected plurality of coordinate pairs based on the portion of the sequence of bits.
The apparatus of claim 35, wherein the means for identifying the set of one or more coordinate pairs is further configured for:

for each coordinate pair of the set of one or more coordinate pairs:

selecting the OAM mode index corresponding to the respective pair; and

selecting the antenna index corresponding to a portion of the sequence of bits.
The apparatus of claim 40, wherein the means for identifying the set of one or more coordinate pairs is further configured for:

for each OAM mode index of a full range of OAM mode indices, selecting a plurality of antenna indices, comprising a subset out of a full set of potential antenna indices, the full set of potential antenna indices mapping to the plurality of antennas.
The apparatus of claim 41, wherein the means for selecting the plurality of antenna indices is further configured for:

referencing a predetermined codebook to identify the selected plurality of antenna indices based on the portion of the sequence of bits.
The apparatus of claim 35, further comprising:

means for transmitting, for each respective coordinate pair of the set of one or more coordinate pairs of the transmitted waveform, a reference signal utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The apparatus of claim 35, further comprising:

means for, for each coordinate pair of a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index, transmitting a first reference signal utilizing the antenna corresponding to the antenna index and the OAM mode corresponding to the OAM mode index.
The apparatus of claim 35, further comprising means for transmitting configuration information comprising one or more of:

a number of candidate OAM mode indices in a full range of OAM mode indices;

a number of candidate antennas in the plurality of antennas;

a number of antennas to be simultaneously used per OAM mode;

a number of coordinate pairs in a full range of pairings of antenna index with OAM mode index; or

a number of coordinate pairs to be simultaneously used.
The apparatus of claim 35, further comprising means for transmitting capability limitation information comprising one or more of:

a set of disallowed candidate coordinate pairs; or

a maximum number of OAM modes allowed per antenna.
An apparatus for wireless communication, comprising:

means for receiving a waveform;

means for identifying an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform; and

means for recovering an information message from the received waveform based on the identified antenna index and OAM mode index.
The apparatus of claim 47, further comprising means for receiving one or more reference signals in association with the waveform.
The apparatus of claim 47, wherein the means for receiving a waveform comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna index corresponds to a UCA circle of a plurality of coaxial UCA circles at a transmitting device.
The apparatus of claim 47, further comprising:

means for receiving a plurality of first reference signals; and

means for, for each respective reference signal of the plurality of reference signals:

mapping the respective reference signal to a corresponding coordinate pair indicating a candidate antenna index and a candidate orbital angular momentum (OAM) mode index;

generating channel model information based on the respective reference signal; and

storing the generated channel model information in memory in association with the corresponding coordinate pair.
The apparatus of claim 50, wherein the identifying the antenna index and the OAM mode index based on the reference signal, further comprise:

means for generating a channel response corresponding to the waveform; and

means for identifying the antenna index and the OAM mode index based on the stored generated channel model information.
A non-transitory computer-readable medium storing computer-executable code comprising instructions for causing a transmitting device to:

receive an information stream comprising a sequence of bits;

identify a set of one or more coordinate pairs based on the sequence of bits, each coordinate pair indicating an antenna index corresponding to an antenna of a plurality of antennas, and an orbital angular momentum (OAM) mode index; and

transmit, for each respective coordinate pair of the identified set of one or more coordinate pairs, a waveform utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The non-transitory computer-readable medium of claim 52, wherein the transmitting device comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna corresponding to the antenna index comprises a UCA circle of the plurality of coaxial UCA circles.
The non-transitory computer-readable medium of claim 52, further comprising instructions for causing the transmitting device to:

for each pair of the identified set of one or more coordinate pairs, jointly select the antenna index and the OAM mode index corresponding to a portion of the sequence of bits.
The non-transitory computer-readable medium of claim 54, wherein the instructions for causing the transmitting device to identify the set of one or more coordinate pairs are further for causing the transmitting device to:

select a plurality of coordinate pairs, comprising a subset out a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index.
The non-transitory computer-readable medium of claim 55, wherein the instructions for causing the transmitting device to select the plurality of coordinate pairs are further for causing the transmitting device to:

reference a predetermined codebook to identify the selected plurality of coordinate pairs based on the portion of the sequence of bits.
The non-transitory computer-readable medium of claim 52, wherein the instructions for causing the transmitting device to identify the set of one or more coordinate pairs are further for causing the transmitting device to:

for each coordinate pair of the set of one or more coordinate pairs:

select the OAM mode index corresponding to the respective pair; and

select the antenna index corresponding to a portion of the sequence of bits.
The non-transitory computer-readable medium of claim 57, wherein the instructions for causing the transmitting device to identify the set of one or more coordinate pairs are further for causing the transmitting device to:

for each OAM mode index of a full range of OAM mode indices, select a plurality of antenna indices, comprising a subset out of a full set of potential antenna indices, the full set of potential antenna indices mapping to the plurality of antennas.
The non-transitory computer-readable medium of claim 58, wherein the instructions for causing the transmitting device to select the plurality of antenna indices are further for causing the transmitting device to:

referenc a predetermined codebook to identify the selected plurality of antenna indices based on the portion of the sequence of bits.
The non-transitory computer-readable medium of claim 52, further comprising instructions for causing the transmitting device to:

transmit, for each respective coordinate pair of the set of one or more coordinate pairs of the transmitted waveform, a reference signal utilizing the antenna corresponding to the antenna index of the respective coordinate pair and an OAM mode corresponding to the OAM mode index of the respective coordinate pair.
The non-transitory computer-readable medium of claim 52, further comprising instructions for causing the transmitting device to:

for each coordinate pair of a full set of potential coordinate pairs, the full set of potential coordinate pairs mapping to a full range of pairings of antenna index with OAM mode index, transmit a first reference signal utilizing the antenna corresponding to the antenna index and the OAM mode corresponding to the OAM mode index.
The non-transitory computer-readable medium of claim 52, further comprising instructions for causing the transmitting device to transmit configuration information comprising one or more of:

a number of candidate OAM mode indices in a full range of OAM mode indices;

a number of candidate antennas in the plurality of antennas;

a number of antennas to be simultaneously used per OAM mode;

a number of coordinate pairs in a full range of pairings of antenna index with OAM mode index; or

a number of coordinate pairs to be simultaneously used.
The non-transitory computer-readable medium of claim 52, further comprising instructions for causing the transmitting device to transmit capability limitation information comprising one or more of:

a set of disallowed candidate coordinate pairs; or

a maximum number of OAM modes allowed per antenna.
A non-transitory computer-readable medium storing computer-executable code comprising instructions for causing a receiving device to:

receive a waveform;

identify an antenna index and an orbital angular momentum (OAM) mode index based on the received waveform; and

recover an information message from the received waveform based on the identified antenna index and OAM mode index.
The non-transitory computer-readable medium of claim 64, further comprising instructions for causing the receiving device to receive one or more reference signals in association with the waveform.
The non-transitory computer-readable medium of claim 64, wherein the receiving device comprises a plurality of coaxial uniform circular array (UCA) circles, and wherein the antenna index corresponds to a UCA circle of a plurality of coaxial UCA circles at a transmitting device.
The non-transitory computer-readable medium of claim 64, further comprising instructions for causing the receiving device to:

receive a plurality of first reference signals; and

for each respective reference signal of the plurality of reference signals:

map the respective reference signal to a corresponding coordinate pair indicating a candidate antenna index and a candidate orbital angular momentum (OAM) mode index;

generate channel model information based on the respective reference signal; and

store the generated channel model information in memory in association with the corresponding coordinate pair.
The non-transitory computer-readable medium of claim 67, wherein the instructions for causing the receiving device to identify the antenna index and the OAM mode index based on the reference signal, are further for causing the receiving device to:

generate a channel response corresponding to the waveform; and

identify the antenna index and the OAM mode index based on the stored generated channel model information.