WO2022078790A2

WO2022078790A2 - Coded csi rs for partial reciprocity

Info

Publication number: WO2022078790A2
Application number: PCT/EP2021/077230
Authority: WO
Inventors: Wolfgang Zirwas
Original assignee: Nokia Technologies Oy
Priority date: 2020-10-16
Filing date: 2021-10-04
Publication date: 2022-04-21
Also published as: WO2022078790A3

Abstract

A system, apparatus, method, and non-transitory computer readable medium for providing coded channel state information (CSI) reference signal (RS) may include a radio access network (RAN) node which is caused to, precode at least one joint port pair associated with at least one radio channel, each of the at least one joint port pair including a spatial domain (SD) component and a frequency domain (FD) component of a corresponding radio channel of the at least one radio channel, generate a channel state information (CSI) matrix including at least one CSI reference signal (RS) sequence, the at least one CSI RS sequence including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence, allocate the CSI matrix to at least one antenna port (AP), the allocating including allocating the at least one CSI RS sequence to the at least one AP, and transmit the allocated CSI RS sequences to at least one UE device using the precoded at least one joint port pair.

Description

CODED CSI RS FOR PARTIAL RECIPROCITY

BACKGROUND

Field

[1] Various example embodiments relate to methods, apparatuses, systems, and/or non-transitory computer readable media for providing coded channel state information (CSI) reference signal (RS) for partial reciprocity.

Description of the Related Art

[2] A 5^th generation mobile network (5G) standard, referred to as 5G New Radio (NR), is being developed to provide higher capacity, higher reliability, and lower latency communications than the 4G long term evolution (LTE) standard. One of the advantages of the 5G standard is the implementation of massive multiple input multiple output (mMIMO) systems, wherein one or more radio access network (RAN) nodes include an array of wireless antennas, e.g., a grid of beams (GoB), which allows the RAN nodes to provide a plurality of radio channels, e.g., beams, datastreams, etc., for uplink (UL) and/or downlink (UL) transmission to/from a plurality of user equipment (UE) devices. RAN nodes employing mMIMO services are expected to offer very high spectral efficiency, high coverage, and high-energy efficiency over conventional RAN node technologies. However, due to the large/massive number of antennas and radio channels operating at the same time, the plurality of radio channels may mutually interfere with each other (e.g., suffer from cross-talk, inter antenna port (AP) interference, etc.) and/or may suffer from inter cell interference, etc.

[3] For example, pilot contamination (e.g., reference signal contamination, and/or interference) is one of the main challenges in widely deploying mMIMO services, particularly for RAN nodes with large numbers of antennas and/or for systems transmitting below 6 GHz radio-frequency bands, which largely coincides with the frequency range (FR) 1 defined for the 5G NR standard (e.g., 410MHz - 7.125 GHz). One approach to mitigate pilot contamination is to use orthogonal channel signal information (CSI) reference signals (RS), which reduces and/or minimizes the amount of interference observed at the CSI RS s by only transmitting on signals orthogonal to each other. However, this approach is not ideal in mMIMO systems where a large number of CSI RSs (e.g., a CSI RS is allocated to each AP of the RAN node) are employed and the resulting pilot signaling overhead becomes very large, e.g., >35% according to some studies, due to the processing of each of the CSI RSs by the RAN node, the UE devices, or both.

[4] Therefore, it is a desired goal to reduce the amount of pilot contamination suffered in mMIMO systems while also reducing the amount of signaling overhead. Additionally, it is a desired goal to exploit the partial reciprocity observed in DL channels and UL channels in these mMIMO systems to lower the computational complexity required to perform CSI measurements at the UE device while maintaining and/or increasing the quality of CSI measurements.

SUMMARY

[5] At least one example embodiment relates to a radio access network (RAN) node.

[6] In at least one example embodiment, the RAN node may include a memory storing computer readable instructions, and at least one processor configured to execute the computer readable instructions to cause the RAN node to precode at least one joint port pair associated with at least one radio channel, each of the at least one joint port pair including a spatial domain (SD) component and a frequency domain (FD) component of a corresponding radio channel of the at least one radio channel, generate a channel state information (CSI) matrix including at least one CSI reference signal (RS) sequence, the at least one CSI RS sequence including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence, allocate the CSI matrix to at least one antenna port (AP), the allocating including allocating the at least one CSI RS sequence to the at least one AP, and transmit the allocated CSI RS sequences to at least one UE device using the precoded at least one joint port pair.

[7] Some example embodiments provide that the RAN node is further caused to allocate the at least one CSI RS sequence to at least one physical resource block (PRB) based on compensation for inter AP interference.

[8] Some example embodiments provide that a total number of APs is greater than a total number of CSI resource elements.

[9] Some example embodiments provide that the RAN node is further caused to allocate power levels of the at least one AP based on estimated CSI estimation performance for the at least one AP. [10] Some example embodiments provide that the RAN node is further caused to renormalize coefficients of the at least one AP based on the allocated power levels of the at least one AP.

[11] Some example embodiments provide that the RAN node is further caused to transmit at least one message to the at least one UE device, the at least one message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the transmitted allocated CSI RS sequences, and the AP number information indicating a number of APs allocated to each UE device.

[12] Some example embodiments provide that the RAN node is further caused to transmit the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

[13] Some example embodiments provide that the RAN node is further caused to transmit at least one message of a second type to the at least one UE device, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements.

[14] At least one example embodiment relates to a user equipment (UE) device.

[15] In at least one example embodiment, the UE device may include a memory storing computer readable instructions, and at least one processor configured to execute the computer readable instructions to cause the UE device to receive at least one allocated channel state information (CSI) reference signal (RS) sequence from at least one radio access network (RAN) node, each of the at least one allocated CSI RS sequence associated with an individual antenna port (AP) of at least one AP of the at least one RAN node, determine at least one relevant AP to the at least one UE device based on the received at least one allocated CSI RS sequence, estimate CSI of each of the at least one relevant AP based on the CSI RS corresponding to the at least one relevant AP, and report the estimated CSI for each of the at least one relevant AP to the at least one RAN node.

[16] Some example embodiments provide that the UE device is further caused to perform the estimating the CSI of the determined at least one relevant AP by calculating a mean value of a channel frequency response (CFR) for a full frequency bandwidth or a full frequency sub bandwidth corresponding to the at least one determined relevant AP. [17] Some example embodiments provide that the UE device is further caused to perform the estimating the CSI for each of the at least one determined relevant AP by compensating for inter AP interference for the at least one determined relevant AP.

[18] Some example embodiments provide that the UE device is further caused to perform the compensating for inter AP interference for the at least one determined relevant AP by using the calculated mean value over a frequency range associated with the at least one determined relevant AP.

[19] Some example embodiments provide that a total number of APs is greater than a total number of CSI resource elements.

[20] Some example embodiments provide that the UE device is further caused to perform the determining the at least one relevant AP by determining a relevant CSI submatrix based on the received at least one allocated CSI RS sequence, the relevant CSI submatrix including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence associated with the UE device.

[21] Some example embodiments provide that the UE device is further caused to perform the determining the at least one relevant AP by performing a Moore Penrose pseudo inverse operation on the received allocated CSI RS sequences for the relevant CSI submatrix.

[22] Some example embodiments provide that the UE device is further caused to receive at least one message from the at least one RAN node, the at least one message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the received at least one allocated CSI RS sequence, and the AP number information indicating a number of APs allocated to each UE device.

[23] Some example embodiments provide that the UE device is further caused to receive the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

[24] Some example embodiments provide that the UE device is further caused to receive at least one message of a second type from the at least one RAN node, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements.

[25] At least one example embodiment relates to a method of operating a RAN node. [26] In at least one example embodiment, the RAN node may include at least one processor for performing the method. The method may include precoding at least one joint port pair associated with at least one radio channel, each of the at least one joint port pair including a spatial domain (SD) component and a frequency domain (FD) component of a corresponding radio channel of the at least one radio channel, generating a channel state information (CSI) matrix including at least one CSI reference signal (RS) sequence, the at least one CSI RS sequence including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence, allocating the CSI matrix to at least one antenna port (AP), the allocating including allocating each of the at least one CSI RS sequence to the at least one AP, and transmitting the allocated CSI RS sequences to at least one UE device using the precoded at least one joint port pair.

[27] Some example embodiments provide that the method further includes allocating the at least one CSI RS sequence to at least one physical resource block (PRB) based on compensation for inter AP interference.

[28] Some example embodiments provide that a total number of APs is greater than a total number of CSI resource elements.

[29] Some example embodiments provide that the method may further include allocating power levels of the at least one AP based on estimated CSI estimation performance for the at least one AP.

[30] Some example embodiments provide that the method may further include transmitting at least one message to the at least one UE device, the message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the allocated CSI RS sequences, and the AP number information indicating a number of APs allocated to each UE device.

[31] Some example embodiments provide that the transmitting the at least one message further includes transmitting the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

[32] Some example embodiments provide that the method may further include transmitting at least one message of a second type to at least one UE device, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements. [33] At least one example embodiment relates to a radio access network (RAN) node.

[34] In at least one example embodiment, the RAN node may include means for precoding at least one joint port pair associated with at least one radio channel, each of the at least one joint port pair including a spatial domain (SD) component and a frequency domain (FD) component of a corresponding radio channel of the at least one radio channel, generating a channel state information (CSI) matrix including at least one CSI reference signal (RS) sequence, the at least one CSI RS sequence including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence, allocating the CSI matrix to at least one antenna port (AP), the allocating including allocating the at least one CSI RS sequence to the at least one AP, and transmitting the allocated CSI RS sequences to at least one UE device using the precoded at least one joint port pair.

[35] Some example embodiments provide that the RAN node includes means for allocating the at least one CSI RS sequence to at least one physical resource block (PRB) based on compensation for inter AP interference.

[36] Some example embodiments provide that a total number of APs is greater than a total number of CSI resource elements.

[37] Some example embodiments provide that the RAN node includes means for allocating power levels of the at least one AP based on estimated CSI estimation performance for the at least one AP.

[38] Some example embodiments provide that the RAN node includes means for renormalizing coefficients of the at least one AP based on the allocated power levels of the at least one AP.

[39] Some example embodiments provide that the RAN node includes means for transmitting at least one message to the at least one UE device, the at least one message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the transmitted allocated CSI RS sequences, and the AP number information indicating a number of APs allocated to each UE device.

[40] Some example embodiments provide that the RAN node includes means for transmitting the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof. [41] Some example embodiments provide that the RAN node includes means for transmitting at least one message of a second type to the at least one UE device, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements.

[42] At least one example embodiment relates to a user equipment (UE) device.

[43] In at least one example embodiment, the UE device may include means for receiving at least one allocated channel state information (CSI) reference signal (RS) sequence from at least one radio access network (RAN) node, each of the at least one allocated CSI RS sequence associated with an individual antenna port (AP) of at least one AP of the at least one RAN node, determining at least one relevant AP to the at least one UE device based on the received at least one allocated CSI RS sequence, estimating CSI of each of the at least one relevant AP based on the CSI RS corresponding to the at least one relevant AP, and reporting the estimated CSI for each of the at least one relevant AP to the at least one RAN node.

[44] Some example embodiments provide that the UE device includes means for performing the estimating the CSI of the determined at least one relevant AP by calculating a mean value of a channel frequency response (CFR) for a full frequency bandwidth or a full frequency sub bandwidth corresponding to the at least one determined relevant AP.

[45] Some example embodiments provide that the UE device includes means for performing the estimating the CSI for each of the determined relevant CSI RS sequences by compensating for inter AP interference for the at least one determined relevant AP.

[46] Some example embodiments provide that the UE device includes means for performing the compensating for inter AP interference for the at least one determined relevant AP by using the calculated mean value over a frequency range associated with the at least one determined relevant AP.

[47] Some example embodiments provide that a total number of APs is greater than a total number of CSI resource elements.

[48] Some example embodiments provide that the UE device includes means for performing the determining the at least one relevant AP by determining a relevant CSI submatrix based on the received at least one allocated CSI RS sequence, the relevant CSI submatrix including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence associated with the UE device. [49] Some example embodiments provide that the UE device includes means for performing the determining the at least one relevant AP by performing a Moore Penrose pseudo inverse operation on the received allocated CSI RS sequences for the relevant CSI submatrix.

[50] Some example embodiments provide that the UE device includes means for receiving at least one message from the at least one RAN node, the at least one message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the received at least one allocated CSI RS sequence, and the AP number information indicating a number of APs allocated to each UE device.

[51] Some example embodiments provide that the UE device includes means for receiving the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

[52] Some example embodiments provide that the UE device includes means for receiving at least one message of a second type from the at least one RAN node, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[53] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more example embodiments and, together with the description, explain these example embodiments. In the drawings:

[54] FIG. 1 illustrates a wireless communication system according to at least one example embodiment;

[55] FIG. 2 illustrates a block diagram of an example RAN node according to at least one example embodiment;

[56] FIG. 3 illustrates a block diagram of a UE device according to at least one example embodiment; [57] FIG. 4A illustrates a first example transmission flow diagram between a RAN node and a UE device according to at least one example embodiment;

[58] FIG. 4B illustrates an example of a CSI matrix and an example relevant AP matrix according to at least one example embodiment;

[59] FIG. 4C illustrates an example of a DCI message including split information and AP number information according to at least one example embodiment;

[60] FIG. 5 A illustrates a pair of CSI matrices according to the conventional art;

[61] FIG. 5B illustrates a plurality of CSI matrices according to at least one example embodiment;

[62] FIG. 6A is a graph illustrating an example of inter AP interference observed on a plurality of APs; and

[63] FIG. 6B is a graph illustrating the results of compensating for inter AP interference according to at least one example embodiment.

DETAILED DESCRIPTION

[64] Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown.

[65] Detailed example embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing the example embodiments. The example embodiments may, however, may be embodied in many alternate forms and should not be construed as limited to only the example embodiments set forth herein.

[66] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the example embodiments. As used herein, the term “and/or,” includes any and all combinations of one or more of the associated listed items.

[67] It will be understood that when an element is referred to as being “connected,” or “coupled,” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected,” or “directly coupled,” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between,” versus “directly between,” “adjacent,” versus “directly adjacent,” etc.).

[68] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the example embodiments. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[69] It should also be noted that in some alternative implementations, the functions/ acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.

[70] Specific details are provided in the following description to provide a thorough understanding of the example embodiments. However, it will be understood by one of ordinary skill in the art that example embodiments may be practiced without these specific details. For example, systems may be shown in block diagrams in order not to obscure the example embodiments in unnecessary detail. In other instances, well-known processes, structures and techniques may be shown without unnecessary detail in order to avoid obscuring example embodiments.

[71] Also, it is noted that example embodiments may be described as a process depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations may be performed in parallel, concurrently or simultaneously. In addition, the order of the operations may be re-arranged. A process may be terminated when its operations are completed, but may also have additional steps not included in the figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination may correspond to a return of the function to the calling function or the main function.

[72] Moreover, as disclosed herein, the term “memory” may represent one or more devices for storing data, including random access memory (RAM), magnetic RAM, core memory, and/or other machine readable mediums for storing information. The term “storage medium” may represent one or more devices for storing data, including read only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other machine readable mediums for storing information. The term “computer-readable medium” may include, but is not limited to, portable or fixed storage devices, optical storage devices, wireless channels, and various other mediums capable of storing, containing or carrying instruction(s) and/or data.

[73] Furthermore, example embodiments may be implemented by hardware circuitry and/or software, firmware, middleware, microcode, hardware description languages, etc., in combination with hardware (e.g., software executed by hardware, etc.). When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the desired tasks may be stored in a machine or computer readable medium such as a non-transitory computer storage medium, and loaded onto one or more processors to perform the desired tasks.

[74] A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.

[75] As used in this application, the term “circuitry” and/or “hardware circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementation (such as implementations in only analog and/or digital circuitry); (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware, and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions); and (c) hardware circuit(s) and/or processor(s), such as microprocessor s) or a portion of a microprocessor s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. For example, the circuitry more specifically may include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, a microprocessor, application-specific integrated circuit (ASIC), etc.

[76] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[77] While the various example embodiments of the present disclosure are discussed in connection with the 5G wireless communication standard for the sake of clarity and convenience, the example embodiments are not limited thereto, and one of ordinary skill in the art would recognize the example embodiments may be applicable to other wireless communication standards, such as the 4G standard, a Wi-Fi standard, a future 6G standard, a future 7G standard, etc.

[78] FIG. 1 illustrates a wireless communication system according to at least one example embodiment. As shown in FIG. 1, a wireless communication system includes a core network 100, and a Data Network 105, a first radio access network (RAN) node 110, a first user equipment (UE) device 120, and a second UE device 130, but the example embodiments are not limited thereto and the example embodiments may include a greater or lesser number of constituent elements. For example, the wireless communication system may include a single UE device, three or more UE devices, two or more RAN nodes, etc.

[79] The RAN node 110 and/or the UE devices 120 and 130 may be connected over a wireless network, such as a cellular wireless access network (e.g., a 3G wireless access network, a 4G-Long Term Evolution (LTE) network, a 5G-New Radio (e.g., 5G) wireless network, a WiFi network, etc.). The wireless network may include a core network 100 and/or a Data Network 105. The RAN node 110 may connect to each other and/or other RAN nodes (not shown), as well as to the core network 100 and/or the Data Network 105, over a wired and/or wireless network. The core network 100 and the Data Network 105 may connect to each other over a wired and/or wireless network. The Data Network 105 may refer to the Internet, an intranet, a wide area network, etc.

[80] The UE device 130 may be any one of, but not limited to, a mobile device, a smartphone, a tablet, a laptop computer, a wearable device, an Internet of Things (loT) device, a sensor (e.g., thermometers, humidity sensors, pressure sensors, motion sensors, accelerometers, etc.), actuators, robotic devices, robotics, drones, connected medical devices, eHealth devices, smart city related devices, a security camera, autonomous devices (e.g., autonomous cars, etc.), a desktop computer and/or any other type of stationary or portable device capable of operating according to, for example, the 5G NR communication standard, and/or other wireless communication standard(s). The UE device 130 may be configurable to transmit and/or receive data in accordance to strict latency, reliability, and/or accuracy requirements, such as URLLC communications, TSC communications, etc., but the example embodiments are not limited thereto.

[81] The wireless communication system further includes at least one RAN node (e.g., a base station, a wireless access point, etc.), such as RAN node 110, etc. The RAN node 110 may operate according to an underlying cellular and/or wireless radio access technology (RAT), such as 5G NR, LTE, Wi-Fi, etc. For example, the RAN node 110 may be a 5G gNB node, a LTE eNB node, or a LTE ng-eNB node, etc., but the example embodiments are not limited thereto. The RAN node 110 may provide wireless network services to one or more UE devices within a cell service area (e.g., a broadcast area, a serving area, a coverage area, etc.) surrounding the respective physical location of the RAN node, such as a cell service area 110A surrounding the RAN node 110, etc. For example, UE devices 120 and 130 are located within the cell service area 110A, and may connect to, receive broadcast messages from, receive paging messages from, receive/transmit signaling messages from/to, and/or access the wireless network through, etc., RAN node 110 (e.g., the RAN node serving the UE devices 120 and 130), but the example embodiments are not limited thereto.

[82] Additionally, the RAN node 110 may be configured to operate in a multi-user (MU) multiple input multiple out (MIMO) mode and/or a massive MIMO (mMIMO) mode, wherein the RAN node 110 transmits a plurality of beams (e.g., radio channels, datastreams, streams, etc.) in different spatial domains and/or frequency domains using a plurality of antennas (e.g., antenna panels, antenna elements, an antenna array, etc.) and beamforming and/or beamsteering techniques. As shown in FIG. 1, each beam may be assigned and/or allocated to a specific logical antenna port (AP), such as AP 1, AP 2, AP 3, AP 4, etc., but the example embodiments are not limited thereto, and there may be a greater or lesser number of APs for each RAN node. According to some example embodiments, each of the beams provided by the RAN node 110 may operate on a separate spatial domain (SD) (e.g., the beams are directed in different directions), but each beam may contain multiple frequency domain (FD) components (e.g., each beam may communicate on a plurality of frequency ranges, etc.). Consequently, each beam and/or AP may be referred to as a joint port pair (Z>i, ), wherein the Z>i refers to the beam identifier (e.g., beam number) and/or SD component (e.g., angle of arrival (AoA) of the beam, etc.), and the refers to the FD component of the beam (e.g., delay time of the beam, etc.). Moreover, one or more of the radio channels and/or beams of the RAN node 110 may have multiple taps and/or frequency components, or in other words a first spatial domain beam may have multiple frequency domain components, and therefore the same radio channel may have multiple joint port pairs (e.g., beam A may include joint port pair 1 (bA, fi), joint port pair 2 (bA, fz), joint port pair 3 (bA, E), joint port pair 4 (bA, fi), etc.), but the example embodiments are not limited thereto.

[83] According to at least one example embodiment, a plurality of RAN nodes and/or cells may coordinate with each other in a joint transmission (JT) cooperative multi point (CoMP) system to mitigate inter cell interference, improve coverage, throughput, and/or system capacity, etc., but the example embodiments are not limited thereto.

[84] Additionally, the UE devices 120 and 130 may perform signal quality measurements based on, or in respect to, the serving RAN node (e.g., RAN node 110) and/or neighboring RAN node(s) (not shown). For example, the UE device 120 and/or 130 may measure (e.g., collect, determine, etc.) signal quality information between one or more of the antenna panels of the UE device 120 and/or 130 and the serving RAN node and/or the neighboring RAN node(s), etc. Examples of the signal quality information may include reference signal received power (RSRP) measurements, received signal strength indicator (RSSI) measurements, reference signal received quality (RSRQ) measurements, signal-to-noise and interference ratio (SNIR) measurements, etc., but the example embodiments are not limited thereto.

[85] According to at least one example embodiment, the UE devices 120 and/or 130 may perform channel state information (CSI) measurements on one or more CSI reference signals (RS), etc. The one or more CSI RSs may be transmitted by the RAN node 110 via the beams (e.g., wireless radio channels, datastreams, etc.) of the RAN node 110. The UE device 120 and/or 130 may then report the measured CSI to the RAN node 110 so that the RAN node 110 may construct, reconstruct, generate, etc., a full pre-coding matrix indicator (PMI) based on the reported CSI of the UE devices. The RAN node 110 then uses the PMI to allocate and/or schedule (e.g., improve allocation, reallocate, optimize allocation, etc.) the resources of the RAN node 110 to the UE devices. For example, the RAN node 110 may reallocate the beams and/or APs allocated and/or assigned to a particular UE device based on the reported CSI measurements (e.g., assign new beams to the UE device if the UE device’s previous CSI measurements were below a desired signal quality threshold, etc.), or may maintain the UE device’s allocated beams based on the reported CSI measurements, etc., but the example embodiments are not limited thereto.

[86] Additionally, according to some example embodiments, the RAN node 110 may adjust (e.g., modify, allocate, compensate for, etc.) power levels of APs and/or signals transmitted on the APs, such as the CSI RSs, etc., based on the reported CSI measurements. Moreover, according to some example embodiments, the RAN node 110 may also adjust the power levels of the APs and/or signals transmitted on the APs based on estimates of the CSI measurements, e.g., estimates that the RAN node 110 and/or the core network 100 calculates without feedback (e.g., CSI reports) from the UE device(s).

[87] The RAN node 110 may be connected to at least one core network element (not shown) residing on the core network 100, such as a core network device, a core network server, access points, switches, routers, nodes, etc., but the example embodiments are not limited thereto. The core network 100 may provide network functions, such as an access and mobility management function (AMF), a session management function (SMF), a policy control function (PCF), a unified data management (UDM), a user plane function (UPF), an authentication server function (AUSF), an application function (AF), and/or a network slice selection function (NSSF), etc., but the example embodiments are not limited thereto.

[88] While certain components of a wireless communication network are shown as part of the wireless communication system of FIG. 1, the example embodiments are not limited thereto, and the wireless communication network may include components other than that shown in FIG. 1, which are desired, necessary, and/or beneficial for operation of the underlying networks within the wireless communication system 100, such as access points, switches, routers, nodes, servers, gateways, etc. [89] FIG. 2 illustrates a block diagram of an example RAN node according to at least one example embodiment. The RAN node may correspond to the RAN node 110 of FIG. 1, but is not limited thereto.

[90] Referring to FIG. 2, a RAN node 2000 may include processing circuitry, such as at least one processor 2100, at least one communication bus 2200, a memory 2300, at least one core network interface 2400, and/or at least one wireless antenna array 2500, but the example embodiments are not limited thereto. For example, the core network interface 2400 and the wireless antenna array 2500 may be combined into a single network interface, etc., or the RAN node 2000 may include a plurality of wireless antenna arrays, a plurality of core network interfaces, etc., and/or combinations thereof. The memory 2300 may include various special purpose program code including computer executable instructions which may cause the RAN node 2000 to perform the one or more of the methods of the example embodiments.

[91] In at least one example embodiment, the processing circuitry may include at least one processor (and/or processor cores, distributed processors, networked processors, etc.), such as the at least one processor 2100, which may be configured to control one or more elements of the RAN node 2000, and thereby cause the RAN node 2000 to perform various operations. The processing circuitry (e.g., the at least one processor 2100, etc.) is configured to execute processes by retrieving program code (e.g., computer readable instructions) and data from the memory 2300 to process them, thereby executing special purpose control and functions of the entire RAN node 2000. Once the special purpose program instructions are loaded into, (e.g., the at least one processor 2100, etc.), the at least one processor 2100 executes the special purpose program instructions, thereby transforming the at least one processor 2100 into a special purpose processor.

[92] In at least one example embodiment, the memory 2300 may be a non-transitory computer-readable storage medium and may include a random access memory (RAM), a read only memory (ROM), and/or a permanent mass storage device such as a disk drive, or a solid state drive. Stored in the memory 2300 is program code (i.e., computer readable instructions) related to operating the RAN node 2000, such as the methods discussed in connection with FIGs. 4A to 6B, the at least one core network interface 2400, and/or at least one wireless antenna array 2500, etc. Such software elements may be loaded from a non-transitory computer-readable storage medium independent of the memory 2300, using a drive mechanism (not shown) connected to the RAN node 2000, or via the at least one core network interface 2400, and/or at least one wireless antenna array 2500, etc.

[93] In at least one example embodiment, the communication bus 2200 may enable communication and data transmission to be performed between elements of the RAN node 2000. The bus 2200 may be implemented using a high-speed serial bus, a parallel bus, and/or any other appropriate communication technology. According to at least one example embodiment, the RAN node 2000 may include a plurality of communication buses (not shown), such as an address bus, a data bus, etc.

[94] The RAN node 2000 may operate as, for example, a 4G RAN node, a 5G RAN node, etc., and may be configured to schedule resource blocks (e.g., physical resource blocks (PRBs), resource elements, etc.) for UE devices connected to the RAN node 2000.

[95] For example, the RAN node 2000 may allocate time-frequency resources of a carrier (e.g., resource blocks with time and frequency dimensions) based on operation on the time domain (e.g., time division duplexing) and the frequency domain (e.g., frequency division duplexing). In the time domain context, the RAN node 2000 will allocate a carrier (or subbands of the carrier) to one or more UEs (e.g., UE 120, UE 130, etc.) connected to the RAN node 2000 during designated upload (e.g., uplink (UL)) time periods and designated download (e.g., downlink (DL)) time periods. When there are multiple UEs connected to the RAN node 2000, the carrier is shared in time such that each UE is scheduled by the RAN node 2000, and the RAN node 2000 allocates each UE with their own uplink time and/or downlink time. In the frequency domain context and/or when performing spatial domain multiplexing of UEs (e.g., MU MIMO, etc.), the RAN node 2000 will allocate separate frequency subbands of the carrier to UEs simultaneously served by the RAN node 2000, for uplink and/or downlink transmissions. Data transmission between the UE and the RAN node 2000 may occur on a radio frame basis in both the time domain and frequency domain contexts. The minimum resource unit for allocation and/or assignment by the RAN node 2000 to a particular UE device corresponds to a specific downlink/uplink time slot (e.g., one OFDM symbol, one slot, one minislot, one subframe, etc.) and/or a specific downlink/uplink resource block (e.g., twelve adjacent subcarriers, a frequency subband, etc.).

[96] For the sake of clarity and consistency, the example embodiments will be described as using the frequency domain, but the example embodiments are not limited thereto and the example embodiments may operate in the time domain. [97] Additionally, the RAN node 2000 may transmit scheduling information via physical downlink common channel (PDCCH) information to the one or more UE devices located within the cell servicing area of the RAN node 2000, which may configure the one or more UE devices to transmit (e.g., UL transmissions via physical uplink control channel (PUCCH) information and/or physical uplink shared channel information (PUSCH), etc.) and/or receive (e.g., DL transmissions via PDCCH and/or physical downlink shared channel information (PDSCH), etc.) data packets to and/or from the RAN node 2000. Additionally, the RAN node 2000 may transmit control messages to the UE device using downlink control information (DCI) messages via physical (PHY) layer signaling, medium access control (MAC) layer control element (CE) signaling, radio resource control (RRC) signaling, etc., but the example embodiments are not limited thereto.

[98] The RAN node 2000 may also include at least one core network interface 2400, and/or at least one wireless antenna array 2500, etc. The at least one wireless antenna array 2500 may include an associated array of radio units (not shown) and may be used to transmit the wireless signals in accordance with a radio access technology, such as 4G LTE wireless signals, 5G NR wireless signals, etc., to at least one UE device, such as UE 120, UE 130, etc. According to some example embodiments, the wireless antenna array 2500 may be a single antenna, or may be a plurality of antennas, etc. For example, the wireless antenna array 2500 may be configured as a grid of beams (GoB) which transmits a plurality of beams in different directions, angles, frequencies, and/or with different delays, etc., but the example embodiments are not limited thereto.

[99] The RAN node 2000 may communicate with a core network (e.g., backend network, backhaul network, backbone network, Data Network, etc.) of the wireless communication network via a core network interface 2400. The core network interface 2400 may be a wired and/or wireless network interface and may enable the RAN node 2000 to communicate and/or transmit data to and from to network devices on the backend network, such as a core network gateway (not shown), a Data Network (e.g., Data Network 105), such as the Internet, intranets, wide area networks, telephone networks, VoIP networks, etc.

£1001 While FIG. 2 depicts an example embodiment of a RAN node 2000, the RAN node is not limited thereto, and may include additional and/or alternative architectures that may be suitable for the purposes demonstrated. HOI] FIG. 3 illustrates a block diagram of an example UE device according to at least one example embodiment. The example UE device of FIG. 3 may correspond to the UE devices 120 and/or 130 of FIG. 1, but the example embodiments are not limited thereto. [102] Referring to FIG. 3, a UE 3000 may include processing circuitry, such as at least one processor 3100, at least one communication bus 3200, a memory 3200, a plurality of wireless antennas and/or wireless antenna panels 3400, at least one location sensor 3500, at least one input/output (EO) device 3600 (e.g., a keyboard, a touchscreen, a mouse, a microphone, a camera, a speaker, etc.), and/or a display panel 3700 (e.g., a monitor, a touchscreen, etc.), but the example embodiments are not limited thereto. According to some example embodiments, the UE 3000 may include a greater or lesser number of constituent components, and for example, the UE 3000 may also include a battery, one or more additional sensors (e.g., thermometers, humidity sensors, pressure sensors, motion sensors, accelerometers, etc.), actuators, a single wireless antenna and/or a single wireless antenna panel, etc. Additionally, the location sensor 3500, the display panel 3700, and/or I/O device 3600, etc., of UE 3000 may be optional.

£1031 In at least one example embodiment, the processing circuitry may include at least one processor (and/or processor cores, distributed processors, networked processors, etc.), such as the at least one processor 3100, which may be configured to control one or more elements of the UE 3000, and thereby cause the UE 3000 to perform various operations. The processing circuitry (e.g., the at least one processor 3100, etc.) is configured to execute processes by retrieving program code (e.g., computer readable instructions) and data from the memory 3200 to process them, thereby executing special purpose control and functions of the entire UE 3000. Once the special purpose program instructions are loaded into the processing circuitry (e.g., the at least one processor 3100, etc.), the at least one processor 3100 executes the special purpose program instructions, thereby transforming the at least one processor 3100 into a special purpose processor.

£104£ In at least one example embodiment, the memory 3200 may be a non-transitory computer-readable storage medium and may include a random access memory (RAM), a read only memory (ROM), and/or a permanent mass storage device such as a disk drive, or a solid state drive. Stored in the memory 3200 is program code (i.e., computer readable instructions) related to operating the UE 3000, such as the methods discussed in connection with FIGs. 4A to 6B, the wireless antenna 3400, and/or the location sensor 3500, etc. Such software elements may be loaded from a non-transitory computer- readable storage medium independent of the memory 3200, using a drive mechanism (not shown) connected to the UE 3000, or via the wireless antenna 3400, etc. Additionally, the memory 3200 may store network configuration information, such as system information, etc., for communicating with at least on RAN node, e.g., RAN node 110, etc., accessing a wireless network, etc., but the example embodiments are not limited thereto.

£1051 In at least one example embodiment, the at least one communication bus 3200 may enable communication and data transmission to be performed between elements of the UE 3000. The bus 3200 may be implemented using a high-speed serial bus, a parallel bus, and/or any other appropriate communication technology. According to at least one example embodiment, the UE 3000 may include a plurality of communication buses (not shown), such as an address bus, a data bus, etc.

£1061 The UE 3000 may also include a plurality of wireless antenna panels 3400 (e.g., a plurality of wireless antennas, etc.). The plurality of wireless antenna panels 3400 may include a plurality of associated radio units (not shown) and may be used to transmit wireless signals in accordance with at least one desired radio access technology, such as 4G LTE , 5G NR, , Wi-Fi, etc. The plurality of wireless antenna panels 3400 may be located at the same or different physical locations on the body of the UE 3000, may have the same or different orientations, may operate in the same or different frequency ranges, may operate in accordance with the same or different radio access technology, etc. The UE 300 may use beamforming and/or beamsteering techniques with the plurality of wireless antenna panels 3400 to generate one or more beams (e.g., wireless radio channels, datastreams, streams, APs, etc.) and transmit and/or receive on each of the beams. For example, the UE 3000 may have 1 to 4 beams/APs, etc., however the example embodiments are not limited thereto. According to some example embodiments, the plurality of wireless antenna panels 3400 may be a single antenna, etc.

[107] Additionally, according to at least one example embodiment, the UE 3000 may collect (e.g., measure, determine, etc.) signal quality information with regards to the signal(s) transmitted by a serving RAN node, e.g., RAN node 110, etc. The UE 3000 may collect and/or measure the signal quality information at each antenna panel of the plurality of antenna panels 3400 included in the UE 3000 by measuring CSI information of a pilot signal, reference signal, a CSI RS, etc., but the example embodiments are not limited thereto. The CSI information may include at least one of the reference signal received power (RSRP) measurements, received signal strength indicator (RS SI) measurements, reference signal received quality (RSRQ) measurements, signal-to-noise and interference ratio (SNIR) measurements, etc., but the example embodiments are not limited thereto.

£1081 The UE 3000 may also include at least one location sensor 3500 to calculate the absolute and/or relative location of the UE 3000. The at least one location sensor 3500 may be a GNSS sensor, such as a GPS sensor, a GLONASS sensor, a Galileo sensor, a Beidou sensor, etc., an inertial movement sensors, such as a gyroscope, an accelerometer, an altimeter, etc. Additionally, the location sensor 3500 and/or the processor 3100 may also use cellular network based positioning services, such as a cellular network location service (e.g., a location management function (LMF) service of the core network), an Assisted-GPS (A-GPS) function, etc., to determine the current location of the UE 3000. £1091 While FIG. 3 depicts an example embodiment of a UE 3000, the UE device is not limited thereto, and may include additional and/or alternative architectures that may be suitable for the purposes demonstrated.

£110 FIG. 4A illustrates a first example transmission flow diagram between a RAN node and a UE device according to at least one example embodiment. FIG. 4B illustrates an example of a CSI matrix and an example relevant AP matrix according to at least one example embodiment. FIG. 4C illustrates an example of a DCI message including split information and AP number information according to at least one example embodiment. [Ill] Referring now to FIG. 4A, according to at least one example embodiment, a RAN node 110 (e.g., a gNB node, aLTE ng-eNB node, a core network element, a cloud network element, etc.), may perform a method of allocating CSI RS sequences (e.g., orthogonal CSI RS sequences, coded CSI RS sequences, etc.) to a plurality of APs in order to reduce, limit and/or minimize the overhead for processing the CSI RSs for the RAN node 110 and/or the UE device 120 based on the partial reciprocity principle. More specifically, in one or more example embodiments, a RAN node 110 may receive a UL sounding reference signal (SRS) based channel estimation from at least one UE device. The RAN node 110 may use the UL SRS based channel estimation to determine the angle of arrival (AoA) (e.g., SD component) and time delay values (e.g., FD component) for the DL channel corresponding to the UL SRS channel estimation based on the channel reciprocity principle between UL channels and DL channels. However, due to small-scale fading experienced in real-world radio communications, complex coefficients for the DL channel(s) may not and/or cannot be estimated based on measurements from the corresponding UL radio channel.

£1121 In the conventional art, the UE device must calculate and/or estimate all coefficients for each AP/CSI RS it receives, including the AoA and time delay values, and report the CSI to the RAN node. However, as previously discussed, the number of APs may be very large, particularly for mMIMO systems, and therefore the calculation/processing/reporting, etc., overhead for becomes very large as well. Accordingly, at least one example embodiment exploits the partial reciprocity by having the RAN node use the inferred AoA and time delay values from the UL SRS channel estimations, precode each AP/CSI RS by frequency shifting each AP/CSI RS to the zerodelay value time domain tap. The UE device then only calculates the complex coefficient for each AP/CSI RS it receives and reports the complex coefficients and/or other CSI to the RAN node 110, thereby reducing the amount of calculating/processing performed by the UE device, as well as reducing the overhead associated with reporting the CSI to the RAN node 110. Additional performance efficiencies may also be observed based on the fact that many UE devices are battery powered, and with the reduced amount of CSI calculations needed to be performed by the UE device, the battery life may be improved, etc.

£1131 In operation S4010, the RAN node 110 may allocate (e.g., assign, associate with, etc.) a plurality of joint port pairs with a plurality of radio channels and/or beams of the RAN node 110. Each of the joint port pairs may include a SD component (e.g., an angle of arrival (AoA), etc.), and a FD component (e.g., a delay of the radio channel, a tap, etc.). The RAN node 110 may further allocate each joint port pair to an AP of the RAN node 110, wherein each AP is associated with an individual CSI RS and corresponding CSI RS sequence for DL transmission. The CSI RS sequence refers to a plurality of CSI resource elements (e.g., defined as 32 resource elements in the 5G standard, but not limited thereto) included in a physical resource block (PRB) that is transmitted over the corresponding AP/radio channel/beam. Because the RAN node 110 allocates each joint port pair to an AP, the number of APs allocated by the RAN node 110 may be greater than the number of radio channels present at the RAN node 110, but the example embodiments are not limited thereto. The RAN node 110 may then precode the plurality of joint port pairs by time delay shifting the joint port pairs to the zero delay position (phase slope in frequency domain), or in other words time shift the corresponding AP/CSI RS to the zero delay position, but the example embodiments are not limited thereto.

£1141 In operation S4020, the RAN node 110 may determine the cardinality (e.g., total number) of joint port pairs and/or APs associated with the radio channels of the RAN node 110, and then determine whether the cardinality is less than or equal to a desired and/or maximum number of orthogonal CSI RS sequences available to the RAN node 110. In operation S4030, the RAN node 110 may determine whether the cardinality of the joint port pairs and/or APs of the RAN node 110 is greater than the desired and/or maximum number of orthogonal CSI RS sequences available to the RAN node 110.

11151 In operation S4040, the RAN node 110 may then generate (e.g., construct, determine, calculate, set, etc.) a matrix for the plurality of CSI RSs of the RAN node 110 based on the joint port pairs associated with and/or corresponding to the radio channels and/or APs of the RAN node 110. As illustrated in FIG. 4B, the matrix, e.g., a CSI matrix, may include a plurality of orthogonal CSI RS sequences (e.g., rows 4110, 4120, 4130, 4140, etc.) and/or a plurality of coded non-orthogonal CSI RS sequences (e.g., rows 4150, 4160, etc.) allocated, assigned, and/or correspond to each AP (e.g., an AP identifier, etc.) of the total set of APs of the RAN node 110, however the example embodiments are not limited thereto. According to at least one example embodiment, the coded non-orthogonal CSI RS sequences {a_i;} may be any suitable non-orthogonal sequence, and for example, may be Vandermonde-like elements, where a_t j

and where a is power normalization factor adapted to the length of the non-orthogonal coded CSI sequence, but the example embodiments are not limited thereto.

[116] According to at least one example embodiment, if the cardinality of the joint port pairs is less than or equal to a desired and/or a maximum number of orthogonal CSI RS sequences (e.g., a first type of CSI RS sequences) available to the RAN node 110 (e.g., 32 orthogonal CSI RS sequences, etc.), the RAN node 110 allocates orthogonal CSI RS sequences to each of the joint port pairs/APs, and adds the allocated CSI RS sequences to the CSI matrix. In other words, CSI matrix may include only the number of CSI RS sequences necessary for the number of joint port pairs/APs of the RAN node 110, etc.

[117] According to some example embodiments, the total number of orthogonal CSI RS sequences may be constrained by the maximum number of CSI RS ports defined by the 5G standard (e.g., 32 CSI RS ports for 5G NR Release 16, etc.), but the example embodiments are not limited thereto, and the desired number of orthogonal CSI RS sequences may be greater or less than 32. Additionally, according to some example embodiments, the RAN node 110 may use a mix of orthogonal CSI RS sequences and coded non-orthogonal CSI RS sequences, or may use only coded non-orthogonal CSI RS sequences, etc., even if the cardinality of the joint port pairs is less than or equal to the desired number of orthogonal CSI RS sequences.

[118] Additionally, if the cardinality of the joint port pairs is greater than the desired number, the RAN node 110 may then allocate and/or assign coded non-orthogonal CSI RS sequences (e.g., a second type of CSI RS sequences) to the remaining number of joint port pairs and/or APs of the RAN node 110. For example, if the total number of joint port pairs/ APs of the RAN node 110 is 64, then the RAN node 110 may allocate 32 orthogonal CSI RS sequences to 32 of the joint port pairs, and may allocate 32 non- orthogonal CSI RS sequences to the remaining joint port pairs, etc. The RAN node 110 may add the allocated coded non-orthogonal CSI RS sequences to the CSI matrix, etc. £1191 However, the example embodiments are not limited thereto, and the RAN node 110 may use a desired number that is less than the maximum number of orthogonal CSI RS sequences allowed by the 5G standard (or other standard). For example, the desired number may be 16, and the RAN node 110 may allocate the first 16 joint port pairs to 16 orthogonal CSI RS sequences and then “switch” the allocation of the remaining number of joint port pairs to non-orthogonal CSI RS sequences, etc.

[120] According to at least one example embodiment, the CSI matrix may include the relevant CSI RS sequences for a plurality of UE devices, but is not limited thereto. In other words, because the CSI matrix includes all of the CSI RS sequences that are allocated to every AP of the RAN node 110, the CSI matrix will include the CSI RS sequences relevant to other UE devices besides UE device 120. Each set of CSI RS sequences relevant to a particular UE device may considered a “submatrix” of the CSI matrix, and each submatrix may be associated with and/or correspond to a particular UE device of a plurality of UE devices connected to the RAN node 110. Moreover, individual CSI RS sequences may be shared between (e.g., relevant to) two or more UE devices and/or APs based on the commonality of the SD component of the corresponding joint port pair.

[121] According to some example embodiments, the RAN node 110 may also define, allocate, and/or adjust power levels of one or more of the joint port pairs/ APs/radio channels of the RAN node 110, as well as determine which CSI RS sequences will be allocated to the one or more UE devices (e.g., UE 120, etc.) connected to the RAN node (e.g., determine the split level of the CSI RS sequences, etc.), but the example embodiments are not limited thereto. The RAN node 110 may allocate the power levels based on previously received CSI reports (e.g., UL SRS information, etc.) from one or more UE devices (e.g., UE 120, etc.) connected to the RAN node 110, and/or may be allocated based on estimates of the CSI (e.g., estimated CSI estimation performance) estimated by (e.g., calculated by, determined by, etc.) the RAN node 110 and/or the core network 100, based on, for example, network conditions, environmental conditions, historical network and/or UE-specific usage patterns, etc., but the example embodiments are not limited thereto. As an example, the RAN node 110 may estimate complex coefficients of the joint port pairs based on the previously received UL SRS information and then allocate the power levels of the joint port pairs based on the estimated complex coefficients, etc.

[122] Referring again to FIG. 4B, each CSI RS sequence (orthogonal or non-orthogonal) may include a plurality of resource elements allocated to the individual CSI RSs. According to at least one example embodiment, the CSI resource elements may correspond to an OFDM symbol assigned to the CSI RS sequence, e.g., the symbol “1” in FIG. 4B, but the example embodiments are not limited thereto and the OFDM symbol may be any valid OFDM symbol.

[123] Referring again to FIG. 4A, in operation S4050, the RAN node 110 may transmit at least one CSI RS-related message (e.g., a first type of message, etc.) to one or more of the UE devices connected to the RAN node 110, e.g., UE 120, including split information and/or AP number information, but the example embodiments are not limited thereto. The CSI-related message(s) may be transmitted as a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof, etc., but is not limited thereto.

£1241 As shown in FIG. 4C, the split information (e.g., split level, etc.) refers to the ratio between the number of orthogonal CSI RS sequences to non-orthogonal CSI RS sequences allocated to each UE device connected to the RAN node 110. For example, as shown in FIG. 4C, the split level may be “2/3” wherein the “2” indicates the number of non-orthogonal CSI RS sequences allocated to a particular UE device for every “3” orthogonal CSI RS sequences allocated to the UE device, etc. The split level may be any desired ratio, and may be set and/or configured by the RAN node 110, by the core network 100, by a network administrator, etc.

[125] According to some example embodiments, the CSI RS-related message may also include AP number information. The AP number information indicates the total number of CSI RS sequences allocated to each UE device connected to the RAN node 110. For example, as shown in FIG. 4C, 8 CSI RS sequences may be allocated to a UE1, 5 CSI RS sequences may be allocated to a UE2, and 5 CSI RS sequences may be allocated to a UE3, etc., but the example embodiments are not limited thereto, and for example each UE may be assigned the same number of CSI RS sequences, etc. According to at least one example embodiment, the UE device 120 may use the split information and/or the AP number information to determine how many and/or which joint port pairs/ APs/CSI RSs to listen for and/or to determine how many or for which joint pairs/ APs to measure CSI, but the example embodiments are not limited thereto, and other rules may be used by the UE device to determine the types and total number relevant CSI RS sequences allocated to the UE devices.

£1261 For example, in some example embodiments, the RAN node 110 may transmit a second type of message (e.g., message of a second type, etc.) to each UE device connected to the RAN node 110 including information (e.g., at least one indicator bit) indicating that a total number of APs is higher than a total number of CSI RS resource elements, etc.

£1271 As another example, the message of the second type may include information indicating that every allocated CSI RS sequence is an orthogonal CSI RS sequence or every allocated CSI RS sequence is a coded non-orthogonal CSI RS sequence (e.g., non- orthogonal CSI RS sequence), etc.

£128£ In some example embodiments, it is appreciated that the second type of message may come at any time relative to the first type of message (e.g., the CSI RS-related message, etc.), for example, before, after, or during (simultaneously), etc. In some further example embodiments a message may comprise one or more bits, and the one or more bits may indicate a relative comparison, e.g., that a ‘ T means the number of APs is higher than the number of CSI RS resource elements and a ‘0’ means vice versa, etc.

[129] Referring again to FIG. 4 A, in operation S4060, the RAN node 110 may transmit the precoded (e.g., time shifted) joint port pairs/ APs/CSI RS sequences to one or more UE devices, such as UE 120. According to at least one example embodiment, the RAN node 110 may transmit the precoded joint port pairs and/or the allocated CSI RS sequences over the desired and/or maximum number of CSI resource elements available to the RAN node 110 (e.g., 32 CSI resource elements, etc.), but the example embodiments are not limited thereto.

£1301 In operation S4070, the UE 120 may receive CSI RS sequences transmitted by the RAN node 110 and may determine the relevant AP allocated to the UE 120 based on the allocated CSI RS sequences. More specifically, the UE 120 receives one or more allocated CSI RS sequences on the relevant radio channels and/or APs that the UE 120 is connected to the RAN node 110. In other words, it is assumed that irrelevant (e.g., CSI RS sequences for other UE devices, etc.) are either not received by the UE 120 because they are transmitted in a different direction, etc., or is received by the UE 120 but the power level associated with the irrelevant CSI RS sequences is below a desired power threshold so the UE 120 ignores and/or filters out the irrelevant CSI RS sequences, etc. The method for determining the relevant CSI RS sequences will be discussed in further detail in connection with FIGs. 5A and 5B.

1131] The UE 120 then determines the relevant AP identifier(s) associated with the relevant precoded CSI RS sequences, and estimates and/or measures the CSI for each of the relevant APs based on the CSI RS resource element(s) for the corresponding relevant CSI RS sequence. For example, the UE 120 may perform a mean value operation (e.g., averaging) of the channel frequency response (CFR) for the full frequency bandwidth and/or a full frequency sub-bandwidth corresponding to the relevant precoded joint port pair/AP/CSI RS sequence to determine and/or estimate the complex coefficients (e.g., taps) associated with the joint port pairs/AP/CSI RS sequence, etc., but the example embodiments are not limited thereto. Additionally, the UE 120 may compensate for inter AP interference (e.g., filter out the inter AP interference, etc.) for the relevant joint port pairs/APs using the calculated mean value over the frequency domain (e.g., over a frequency range associated with and/or corresponding to the relevant joint port pairs/APs, etc.), however the example embodiments are not limited thereto and other compensation techniques may be used.

£132£ In operation S4080, the estimated and/or measured CSI is reported to the RAN node 110, for example as UL SRS information, etc. The reported CSI may include the results of the mean value operation of the CFR for each relevant joint port pair/AP, and/or may include the calculated and/or estimated complex coefficients of the relevant joint port pairs/APs, etc. £1331 In operation S4090, the RAN node 110 may construct and/or reconstruct a full PMI based on the reported CSI from the one or more UE devices connected to the RAN node 110, etc. Additionally, the RAN node 110 may use the newly reported CSI to compensate for inter AP interference on the RAN-side by adjusting the power levels of the APs and/or reallocating APs/CSI RS sequences to the one or more UE devices connected to the RAN node 110 (e.g., the UE devices that the RAN node 110 simultaneously schedules), etc. Additionally, the RAN node 110 may renormalize the coefficients of the plurality of APs (e.g., reverse the precoding of the joint port pairs and/or APs, etc.) after the power levels have been allocated and/or reallocated based on the calculated mean values of the reported APs.

[134] Referring now to FIGs. 6A and 6B, FIG. 6A is a graph derived from a simulation illustrating the impact that inter AP interference may cause over 50 PRB, which is the equivalent of 10 MHz signal bandwidth. In the simulation of FIG. 6 A, 20 relevant APs corresponding to 50 PRB were set to output an amplitude value of “1”. In an environment where there is no inter AP interference, the graph should be level and the amplitudes for all of the 20 APs should be 1. As seen in FIG. 6A, the inter AP interference between the 20 APs cause the amplitudes to range from 0.5 to 2.0, indicating severe interference in the signal. However, when the inter AP interference is compensated for, such as when the UE 120 applies the mean value of the CFR for all 20 relevant APs as simulated in FIG. 6B, the amplitude of the inter AP interference is reduced to -0.1 to 0.15. Accordingly, significant reduction of inter AP interference may be achieved based on the calculation and/or estimation of the CSI for the relevant APs/joint port pairs, etc.

[135] According to at least one example embodiment, the RAN node 110 may also allocate and/or reallocate the CSI RS sequences (e.g., the orthogonal CSI RS sequences and/or the coded non-orthogonal CSI RS sequences) to appropriate physical resource blocks (PRBs) based on the compensation applied to the APs by the RAN node 110 and/or the UE 120, or in other words, the CSI RS sequences are allocated to the PRBs corresponding to the compensated APs, etc.

[136] Referring now to FIGs. 5A and 5B, FIG. 5A illustrates a pair of CSI matrices according to the conventional art and FIG. 5B illustrates a plurality of CSI matrices according to at least one example embodiment.

£1371 As previously discussed, the UE 120 may allocate receive one or more precoded joint port pair as one AP. Assuming that the number of APs included in the CSI matrix is greater than the maximum number of CSI resource elements provided for in the relevant wireless RAT (e.g., 32 CSI resource elements in the 5G NR Release 16, etc.), the CSI matrix will include both orthogonal CSI RS sequences and non-orthogonal CSI RS sequences. As shown in FIG. 5A, in order to accommodate the extra number of non- orthogonal CSI RS sequences, it has been proposed in the conventional art that an extension of resource blocks be added to the PRBs associated with each relevant AP to a UE device. In other words, the non-orthogonal CSI RS extension would require the increase in the number of resource elements allocated to CSI RSs associated with each AP of the RAN node 110, etc., which would decrease the number of resource elements available for other purposes, increase the computational complexity of determining the relevant CSI RSs, etc.

£1381 At least one example embodiment solves the above issues of the conventional art by overlaying the non-orthogonal CSI RS sequences onto the resource blocks associated with the orthogonal CSI RS sequences (e.g., performing matrix multiplication using the non-orthogonal CSI RS sequences and the orthogonal RS sequences) allocated for each AP, as shown in FIG. 5B. The use of overlays results allows all of the CSI RS sequences allocated to the APs of the RAN node to be encoded into the designated number of CSI resource elements in a PBR, thereby reducing the overhead associated with the conventional non-orthogonal sequence extension approach.

[139] Additionally, in order for the UE device 120 to determine its relevant CSI RS sequences, according to at least one example embodiment, the UE device 120 may decode the overlaid non-orthogonal CSI RS sequences to determine the relevant CSI RS sequences for the UE device 120 by performing an inverse operation, such as a Moore Penrose pseudo inverse option, etc., and/or any other mathematical operation which would produce an identity matrix for the overlaid non-orthogonal CSI RS sequences, etc. The result of the inverse operation provides the UE device 120 with the relevant CSI RS sequences, e.g., the submatrix of the CSI matrix corresponding to the relevant AP, etc. £1401 As discussed above, the 3GPP 5G Release 16 protocol defines the maximum number of CSI RS ports as 32 ports, and therefore there may only be a maximum of 32 CSI resource elements and/or CSI RS sequences, etc. However, a RAN node may desire and/or require a large number of joint port pairs/ APs (e.g., greater than the 32 CSI resource elements available), particularly when implementing mMIMO services. Accordingly, at least one example embodiment overcome this limitation by allocating one or more coded non-orthogonal CSI RS sequences to the joint port pairs/ APs that exceed the maximum number of CSI resource elements available to the RAN node.

1141] Various example embodiments are directed towards a wireless network system including RAN nodes for generating CSI matrices, and UE devices for determining relevant APs based on the CSI matrices. Accordingly, one or more of the example embodiments provide methods for reducing, limiting and/or minimizing the overhead for processing CSI RS by allocating APs to orthogonal CSI RS sequences and non- orthogonal coded CSI RS sequences. Additionally, one or more example embodiments reduce the amount of pilot contamination and/or inter AP interference suffered in mMIMO systems while also reducing the amount of signaling overhead required.

£1421 This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A radio access network (RAN) node comprising: a memory storing computer readable instructions; and at least one processor configured to execute the computer readable instructions to cause the RAN node to: precode at least one joint port pair associated with at least one radio channel, each of the at least one joint port pair including a spatial domain (SD) component and a frequency domain (FD) component of a corresponding radio channel of the at least one radio channel, generate a channel state information (CSI) matrix including at least one CSI reference signal (RS) sequence, the at least one CSI RS sequence including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence, allocate the CSI matrix to at least one antenna port (AP), the allocating including allocating the at least one CSI RS sequence to the at least one AP, and transmit the allocated CSI RS sequences to at least one UE device using the precoded at least one joint port pair.

2. The RAN node of claim 1, wherein the RAN node is further caused to: allocate the at least one CSI RS sequence to at least one physical resource block (PRB) based on compensation for inter AP interference.

3. The RAN node of any one of claims 1 to 2, wherein a total number of APs is greater than a total number of CSI resource elements.

4. The RAN node of any one of claims 1 to 3, wherein the RAN node is further caused to: allocate power levels of the at least one AP based on estimated CSI estimation performance for the at least one AP.

5. The RAN node of claim 4, wherein the RAN node is further caused to: renormalize coefficients of the at least one AP based on the allocated power levels of the at least one AP.

6. The RAN node of any one of claims 1 to 5, wherein the RAN node is further caused to: transmit at least one message to the at least one UE device, the at least one message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the transmitted allocated CSI RS sequences, and the AP number information indicating a number of APs allocated to each UE device.

7. The RAN node of claim 6, wherein the RAN node is further caused to transmit the at least one message as at least one of: a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

8. The RAN node of any one of claims 1 to 6, wherein the RAN node is further caused to: transmit at least one message of a second type to the at least one UE device, the at least one message of the second type including information indicating whether a total number of APs is higher than a total number of CSI RS resource elements.

9. A user equipment (UE) device, comprising: a memory storing computer readable instructions; and at least one processor configured to execute the computer readable instructions to cause the UE device to: receive at least one allocated channel state information (CSI) reference signal (RS) sequence from at least one radio access network (RAN) node, each of the at least one allocated CSI RS sequence associated with an individual antenna port (AP) of at least one AP of the at least one RAN node, determine at least one relevant AP to the at least one UE device based on the received at least one allocated CSI RS sequence, estimate CSI of each of the at least one relevant AP based on the CSI RS corresponding to the at least one relevant AP, and report the estimated CSI for each of the at least one relevant AP to the at least one RAN node.

10. The UE device of claim 9, wherein the UE device is further caused to perform the estimating the CSI of the determined at least one relevant AP by: calculating a mean value of a channel frequency response (CFR) for a full frequency bandwidth or a full frequency sub bandwidth corresponding to the at least one determined relevant AP.

11. The UE device of any of claims 9 to 10, wherein the UE device is further caused to perform the estimating the CSI for each of the at least one determined relevant AP by: compensating for inter AP interference for the at least one determined relevant AP.

12. The UE device of claim 11, wherein the UE device is further caused to perform the compensating for inter AP interference for the at least one determined relevant AP by using the calculated mean value over a frequency range associated with the at least one determined relevant AP.

13. The UE device of any of claims 9 to 12, wherein a total number of APs is greater than a total number of CSI resource elements.

14. The UE device any of claims 9 to 13, wherein the UE device is further caused to perform the determining the at least one relevant AP by: determining a relevant CSI submatrix based on the received at least one allocated CSI RS sequence, the relevant CSI submatrix including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence associated with the UE device.

15. The UE device of claim 14, wherein the UE device is further caused to perform the determining the at least one relevant AP by: performing a Moore Penrose pseudo inverse operation on the received allocated CSI RS sequences for the relevant CSI submatrix.

16. The UE device of any of claims 9 to 14, wherein the UE device is further caused to: receive at least one message from the at least one RAN node, the at least one message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the received at least one allocated CSI RS sequence, and the AP number information indicating a number of APs allocated to each UE device.

17. The UE device of claim 16, wherein the UE device is further caused to: receive the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

18. The UE device of any of claims 9 to 17, wherein the UE device is further caused to: receive at least one message of a second type from the at least one RAN node, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements.

19. A method of operating a radio access network (RAN) node, the RAN node including at least one processor for performing the method, the method comprising: precoding at least one joint port pair associated with at least one radio channel, each of the at least one joint port pair including a spatial domain (SD) component and a frequency domain (FD) component of a corresponding radio channel of the at least one radio channel; generating a channel state information (CSI) matrix including at least one CSI reference signal (RS) sequence, the at least one CSI RS sequence including at least one orthogonal CSI RS sequence and/or at least one coded non-orthogonal CSI RS sequence; allocating the CSI matrix to at least one antenna port (AP), the allocating including allocating the at least one CSI RS sequence to the at least one AP; and transmitting the allocated CSI RS sequences to at least one UE device using the precoded at least one joint port pair.

20. The method of claim 19, further comprising: allocating the at least one CSI RS sequence to at least one physical resource block (PRB) based on compensation for inter AP interference.

21. The method of any of claims 19 to 20, wherein a total number of APs is greater than a total number of CSI resource elements.

22. The method of any of claims 19 to 21, further comprising: allocating power levels of the at least one AP based on estimated CSI estimation performance for the at least one AP.

23. The method of any of claims 19 to 22, further comprising: transmitting at least one message to the at least one UE device, the message including split information and AP number information, the split information indicating a ratio of orthogonal CSI RS sequences to coded non-orthogonal CSI RS sequences included in the allocated CSI RS sequences, and the AP number information indicating a number of APs allocated to each UE device.

24. The method of claim 23, wherein the transmitting the at least one message further includes: transmitting the at least one message as at least one of a downlink control information (DCI) message, a medium access control (MAC) layer control element (CE) message, a radio resource control (RRC) message, or any combinations thereof.

25. The method of any of claims 19 to 24, further comprising: transmitting at least one message of a second type to at least one UE device, the at least one message of the second type including information indicating a total number of APs is higher than a total number of CSI RS resource elements.