Reference data based autocalibration

Abstract

A method of wireless communication includes configuring a resource manager to schedule transmissions by interfacing with a radio access network (RAN) according to an application programmer's interface (API), wherein the RAN is providing wireless connectivity to a plurality of user devices, scheduling multiple first transmissions from the RAN to one or more target user devices by sending multiple first scheduling messages according to the API, indicating, for each first scheduling message, that the resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme. The operational points of the multiple transmissions are perturbed according to the feedback.

Description

PCT Patent Application Attorney Docket No. 119314.8127.WO00REFERENCE DATA BASED AUTOCALIBRATIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U. S. Provisional Application No. 63 / 740,539, filed on December 31, 2024, entitled “REFERENCE DATA BASED AUTOCALIBRATION”, the disclosure of which is hereby incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The present document relates to wireless communication.BACKGROUND

[0003] Due to an explosive growth in the number of wireless user devices and the amount of wireless data that these devices can generate or consume, current wireless communication networks are fast running out of bandwidth to accommodate such a high growth in data traffic and provide high quality of service to users.

[0004] Various efforts are underway in the telecommunication industry to come up with next generation of wireless technologies that can keep up with the demand on performance of wireless devices and networks. Many of those activities involve situations in which a large number of user devices may be served by a network.SUMMARY

[0005] This document discloses techniques that may be used by wireless networks to achieve several operational improvements.

[0006] In an example aspect, a wireless communication method is disclosed. The method includes configuring a resource manager to schedule transmissions by interfacing with a radio access network (RAN) according to an application programmer’s interface (API), wherein the RAN is providing wireless connectivity to a plurality of user devices, scheduling multiple first transmissions from the RAN to one or more target user devices by sending multiple first scheduling messages according to the API, indicating, for each first scheduling message, that the1184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme. The operational points of the multiple transmissions are perturbed according to the feedback.

[0007] In another example aspect, another wireless communication method is disclosed. The method includes configuring a distributed unit (DU) of a radio access network (RAN) to operate according to an application programmer’s interface (API) with a resource manager, wherein the RAN is providing wireless connectivity to a plurality of user devices; receiving, over the API, multiple first scheduling messages that schedule multiple first transmissions from the RAN to one or more target user devices according to the API; receiving an indication, for each first scheduling message, that the resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme; and performing wireless operations according to the each first scheduling message.

[0008] In another example aspect, a wireless communication apparatus that implements the above-described method is disclosed. The apparatus may include one or more processors configured to control the apparatus to implement the method.

[0009] In yet another example aspect, a wireless system in which the above-described method is implemented is disclosed.

[0010] In yet another example aspect, a computer-readable storage medium that stores processor-executable code for the above-described method is disclosed.

[0011] These, and other, features are described in this document.DESCRIPTION OF THE DRAWINGS

[0012] Drawings described herein are used to provide a further understanding and constitute a part of this application. Example embodiments and illustrations thereof are used to explain the technology rather than limiting its scope.

[0013] FIG. 1 shows an example communication network.

[0014] FIG. 2 shows a simplified example of a wireless communication system in which uplink and downlink transmissions are performed.

[0015] FIG. 3A-3C show examples of beamforming achieved by various embodiments.

[0016] FIG. 4 is a block diagram of an example implementation of channel calibration.2184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00

[0017] FIG. 5 is a block diagram of another example implementation of channel calibration.

[0018] FIG. 6 shows details of an example channel calibration implementation.

[0019] FIG. 7 shows additional details of the example channel calibration implementation.

[0020] FIG. 8 is a flowchart for an example method of wireless communication.

[0021] FIG. 9 is a block diagram of an example hardware platform.

[0022] FIG. 10 is a block diagram of an example implementation of a resource manager operating in a wireless system.

[0023] FIG. 11 is a block diagram of an example network configuration for autocalibration.

[0024] FIG. 12 is a block diagram of another network configuration for autocalibration.

[0025] FIG. 13 is a flowchart of an example method of digital communications.

[0026] FIG. 14 is a flowchart of an example method of digital communications.DETAILED DESCRIPTION

[0027] To make the purposes, technical solutions and advantages of this disclosure more apparent, various embodiments are described in detail below with reference to the drawings. Unless otherwise noted, embodiments and features in embodiments of the present document may be combined with each other.

[0028] Section headings are used in the present document to improve readability of the description and do not in any way limit the discussion or the embodiments to the respective sections only. Furthermore, certain standard-specific terms are used for illustrative purpose only, and the disclosed techniques are applicable to any wireless communication systems.

[0029] 1. Introduction to the wireless communication environment

[0030] The wireless or time-variant nature of the communication channel poses several challenges in designing a transmission protocol suitable for wireless communication scenarios. These days, users expect their wireless devices to work everywhere and in a variety of mobile or stationary situations.

[0031] The time-variant nature of a wireless network and the expectation by users of a reliable, high-bandwidth network connection at any time and in any place creates a tension between the required amount of transmission resources a wireless network needs for overhead signal communications (e.g., for calibrating a wireless channel) and allocating as much transmission bandwidth to user data as possible. Deployments of user devices and network devices having3184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00multiple antennas makes this problem becomes even more challenging because wireless networks may need to calibrate wireless channel to / from each antenna of a multi -antenna device.

[0032] The techniques described in the present application allow for calibration of uplink or downlink wireless network connections using various techniques that provide operational advantages as further described throughout the present document.

[0033] 2. Example wireless systems

[0034] FIG. 1 shows an example of a wireless communication system 100 in which a transmitter device 102 transmits signals to a receiver 104. The signals may undergo various wireless channels and multipaths, as depicted. Some reflectors such as buildings and trees may be static, while others such as cars, may be moving scatterers. The transmitter device 102 may be, for example, a user device, a mobile phone, a tablet, a computer, or another Internet of Things (loT) device such as a smartwatch, a camera, and so on. The receiver device 104 may be a network device such as the base station. The signals transmitted from the base station to the transmitter 102 may experience similar channel degradations produced by static or moving scatterers. The techniques described in the present document may be implemented by the devices in the wireless communication system 100. The terms “transmitter” and “receiver” are simply used for convenience of explanation and as further described herein, depending on the direction of transmission (uplink or downlink), the network station may be transmitting or receiving, and user device may be receiving or transmitting.

[0035] FIG. 2 shows a simplified wireless network to highlight certain aspects of the disclosed technology. A transmitter transmits wireless signals to a receiver in the wireless network. Some transmissions in the network, variously called as downlink or downstream transmissions, a network-side node such as a base station acts as a transmitter of wireless signals and one or more user devices act as the receiver of these wireless signals. For some other transmissions, as depicted in FIG. 2, the direction of transmission may be opposite. Such transmissions are often called uplink or upstream transmissions. For such transmissions, one or more user devices act as transmitters of the wireless signals and a network-side node such as the base station acts as the receiver of these signals (as depicted in FIG. 2). Other type of transmissions in the network may include device-to-device transmissions, sometimes called direct or sideband transmissions.While the present document primarily uses the terms “downlink” and “uplink” for the sake of4184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00convenience, similar techniques may also be used for other situations in which transmissions in two directions are performed - e.g., inbound or incoming transmissions that are received by a wireless device and outbound or outgoing transmissions that are transmitted by a wireless device. For example, downlink transmissions may be inbound transmissions for a user device, while outbound transmissions for a network device. Similarly, uplink transmission may be inbound transmissions for a network device while outbound transmissions from a wireless device.Therefore, for some embodiments, the disclosed techniques may also be described using terms such as “inbound” and “outbound” transmission without importing any 3GPP-specific or other wireless protocol-specific meaning to the terms “uplink” and “downlink.”

[0036] In frequency division multiplexing (FDM) networks, the transmissions to a base station and the transmissions from the base station may occupy different frequency bands (each of which may occupy continuous or discontinuous spectrum). In time division multiplexing (TDM) networks, the transmissions to a base station and the transmissions from the base station occupy a same frequency band but are separated in time domain using a TDM mechanism such as time slot-based transmissions. Other types of multiplexing are also possible (e.g., code division multiplexing, orthogonal time frequency space, or OTFS, multiplexing, spatial multiplexing, etc.). In general, the various multiplexing schemes can be combined with each other. For example, in spatially multiplexed systems, transmissions to and from two different user devices may be isolated from each other using directional or orientational difference between the two end points (e.g., the user devices and a network station such as a base station).

[0037] 3. Network alignment functions

[0038] Most modem networks implement a network alignment functionality. This functionality refers to aligning timing, phase, and / or gain across transmit and / or receive paths at both sides of a communication channel, e.g., between a base station and user devices (UEs), between UEs in a sidelink, or between devices in direct communication. The alignment may include aligning timing and communication parameters used for transmission. Aligning timing at the transmitter and the receiver allows for error-free transmissions without having to use time gaps for allowing time for receivers to absorb communication propagation delays, thereby improving channel transmission efficiency (e.g., bits per hertz per second). Aligning timing, phase, and gain at the transmitter and the receiver enables signals to interact with each other and the channel in a5184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00coherent manner. This improves network capacity by reducing the probability-of-error when spatial-multiplexing data transmissions to a single (SU) or multiple users (MU).

[0039] In some embodiments, automated calibration of downlink (DL) and uplink (UL) may be performed using a communication protocol that allows exchange of related information. For example, a network may schedule reference signal transmissions from the network to multiple user devices, collect channel state information from the multiple user devices and modify future network operations based on the collected channel state information. The modifications may include, for example, managing allocation of resources for transmissions in the wireless network. A resource manager, implemented on the network side, may be used to control resources such as flows or packets used for channel state measurements, creation of beams for measuring angular locations of user devices, the alignment operation, controlling modulation and coding scheme (MCS) used for reference signal or data transmission, and so on. Various embodiments of the resource manager are disclosed in the present document.

[0040] One example use of the calibration process may be to achieve accurate beamforming to allow spatial multiplexing for multi-input multi-output (MIMO) configuration

[0041] FIG. 3A-3C show an example of beamforming improvements achieved using the channel calibration process described herein. FIG. 3A shows a case in which “ideal” beamforming may occur where the weights wO and wl are selected to form a beam in a desired direction. As depicted, transmission energy is directed spatially with an intended beam-pattern. A main lobe of energy may point in a desired direction (e.g., 15 degrees) while minimal energy may be directed in another desired direction (e.g., -50 degrees). Here, it is assumed that the angle of arrival (AoA) for the target user device has been estimated as disclosed in the present document.

[0042] FIG. 3B shows another example where calibration impairments produce uneven distortion in each transmit or receive chain, and the resulting uncalibrated beam may be formed in a direction that is different from the desired direction as shown in FIG. 3A.

[0043] FIG. 3C shows an embodiment in which transmit path distortions are calibrated and corresponding compensatory timings, gains, and phases are applied in order to produce a beam pattern that is close to the ideal beam pattern as shown in FIG. 3A. In the depicted embodiment, a calibration coefficient alignment is performed by applying an inverse ratio factor of the ratio between two different processing chains of two antenna ports. Alternatively, the calibration6184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00coefficient alignment may be applied to each signal processing path to match each path’s signal distortions to a uniform level. Additionally, or alternatively, the uniform level may be scaled to a predetermined gain value (e.g., based on a bit width of an analog-to-digital converter (ADC) or a digital-to-analog converter (DAC) in the respective signal processing paths.

[0044] In some embodiments, link capacity of a communication link between a transmitter and one or more receivers may be optimized using the alignment operation. Here, a “transmitter” may represent an antenna, an antenna port or a transmission reception point (TRP), as it is variously called for an entity that emanates or receives an electromagnetic wavefront.

[0045] Another operation that may be performed during alignment includes alias detection and correspondingly aligning transmitter and receiver operations in the frequency domain. Another operation that may be performed during alignment includes spatial-alias detection, aligning transmitter and / or receiver relative to a direction vector. The various embodiments disclosed in the present document are further explained using examples from well -understood communication protocols such as Third Generation Partnership Project’s (3GPP) Long Tern Evolution (LTE) protocol, LTE-Advanced (LTE-A) protocol or the Fifth Generation (5G) protocol.

[0046] In Release 10 LTE-Advanced, Channel State Information (CSI) was decoupled from LTE's broadcast Cell-specific Reference Signal (CRS) with Channel State Information -Reference Signals (CSLRS). One of the advantages of such a decoupling is to allow flexible, UE-specific scheduling and precoding of the CSLRS enabling calibration and alignment of individual transmission / reception points, thereby allowing multi-user multiple-input multipleoutput (MU-MIMO) configuration support.

[0047] 4. Brief introduction to CSLRS

[0048] One example of CSLRS is a downlink (DL) reference signal measured by UE for CSI reporting. CSLRS is supported in 5G and LTE-A with TM9 (introduced in LTE release 10) or TM10 (introduced in LTE release 11). 5G-NR and later LTE-A releases allow for many orthogonal CSLRS configurations.

[0049] In 5G-NR and LTE-A networks, nearby cells can be configured with non-zero-power (NZP)-CSLRS and zero-power (ZP)-CSLRS to mitigate measurement interference. Some of the later LTE-A releases add capabilities giving more flexibility to CSLRS and the entire CSI framework, similar to 5G-NR.7184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00

[0050] 5. Using reference data vs CSI-RS for network alignment or calibration

[0051] In a legacy (pre- LTE-A) LTE system, because CSI-RS was not available, transport blocks are used as a reference to estimate link capacity in the form of block error rate BLER with a particular modulation and coding scheme (MCS) and rank. Typical measurements performed using reference data involve two steps:

[0052] (1) Estimate the appropriate MCS for desired BLER range

[0053] (2) Estimate BLER corresponding to MCS estimated in the previous step

[0054] In 5G and LTE-A, the concept of CSI-RS was expanded to use for measuring a channel quality indicator (CQI) representative of quality of the channel between a transmitting and a receiving point. At a receiver, the CSI-RS is received and is used to measure link capacity in the form of (CQI, rank). A CSI report is generated by the receiving device and provided to the transmitting device.

[0055] Although various existing protocols provide the reference signals, some of which have been described above, that may be used for calibration of channels between various transmitterreceiver pairs, the presently disclosed technical solutions may use normal data traffic for channel calibration also. Various embodiments may use a combination of normal user data that may also be marked for calibration and reference (or dummy) data that is not a part of normal user data traffic, but specifically used for calibration.

[0056] 6. Examples of calibration using reference data

[0057] FIG. 4 shows an example flowchart of a process of calibrating a channel using reference data transmissions. At 402, resource may be allocated for transmission of reference data. The allocation of resources may be performed explicitly (e.g., through signaling or indications in control channel transmissions) or implicitly (e.g., by predefined rules about locations of timefrequency resources). In parallel with 402, or after 402, at 404, the MCS of the reference data transmission is adjusted or determined according to a calibration algorithm. In parallel with or after 402 and 404, perturbation used for perturbing a precoder used for precoding the reference data transmissions may be updated (406) to a new value. The process of updating the precoder operational parameters is described throughout the present document. In some embodiments, the precoder may be defined by a precoding gain (gi) and a precoding phase ((pi). For MIMO cases, the precoding gain / phase may be represented by a matrix. In some embodiments, subsequent to8184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00determination of the perturbation value(s) to be used, these values may be used in two different measurement steps. In the first measurement step (comprising 408, 412), the precoder value is changed by increasing (or biasing) its value in one direction using the perturbation values determined in 406. In the second measurement step (410, 414), the precoder value is changed by decreasing or biasing its value in a second direction using the perturbation values determined in 406. In a simplistic case, the two directions may simply be opposite of each other, that is, the perturbation used in the first step (408, 412) may include increasing precoding values and the perturbation used in the second step (410, 414) may include reducing precoding values. In other words, the magnitudes of the two perturbation values (used in 408 / 412 and 410 / 414) are equal and their signs are opposite to each other.

[0058] The BLER estimates obtained at 412 and 414 may be used (at 416) to determine updated phase and gain estimate values that are can be used for subsequent transmissions from the transmitter to the receiver and also for a next measurement cycle for achieving and / or maintaining calibration between the transmitter and the receiver. In some examples, the updated phase and gain estimate values are part of the feedback signal shown in FIG. 4.

[0059] As depicted in FIG. 4, in some embodiments, the calibration by precoding gain and / or phase perturbation may be repeated with N reference data transmissions per iteration. Typically, N is 20 to 40, with reference data transmissions spanning about 20% of physical resource blocks (PRBs) per subframe, occurring every 5 to 20 milliseconds, resulting in a duration of 100 to 800 milliseconds per iteration with reference data using 1 to 4 percent of data transmissions.

[0060] 7. Examples of calibration using CSI-RS

[0061] FIG. 5 shows a process implemented in 5G and similar technologies where CSI-RS transmissions are used for CQI estimation. The overall structure of the process in FIG. 5 is similar to that shown in FIG. 4, and the details for certain blocks will not be repeated in this section. At 502, CSI-RS resources are allocated. At 504, perturbation values are updated. At 506, 510, precoder is biased in one direction and corresponding CQI estimate is obtained. At 508, 512, precoder is biased in a second direction and corresponding CQI estimate is obtained. At 514, based on the two CQI estimates, the values of gain and phase estimates are updated for next iteration. In some examples, the values of phase and gain estimate values are part of the feedback9184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00signal shown in FIG. 5. In this scenario, calibration performed using CSI-RS results in a duration of 8 to 100 milliseconds per iteration.

[0062] 8. Additional implementation examples

[0063] In some examples, using LTE-like protocols (e.g., FIG. 4), the following parameters in an example configuration may be used.

[0064] N_0: # grants for MCS adaption

[0065] N_1: # grants per precoder parameter

[0066] P: periodicity of reference grants (milliseconds, ms)

[0067] N = N_0 + 2*N_1

[0068] Latency = N*P (ms)

[0069] In an example, and for { N_0 = 20; N_1 = 10; P = 15ms }, the number of reference data transmissions per iteration is N = 40 with Latency = 600ms.

[0070] In some examples, using 5G-like protocol (e.g., FIG. 5), the following parameters in an example configuration may be used.

[0071] N_0: # CQI Reports for avg / parameter

[0072] P: periodicity of CSI-Report (ms)

[0073] N = 2*N_0

[0074] Latency = N*P (ms)

[0075] In an example, and for { N_0 = 2; P = 10ms }, the number of CSLReports per iteration is N = 4 with Latency = 40ms.

[0076] In these examples, the overhead may include ZP-CSLRS overhead (e.g., for 7 orthogonal sets) and typically consumes less than 2% of all resources.

[0077] 9. Additional perturbation examples

[0078] In various embodiments, a perturbation may be an additive or a multiplicative operation applied to transmit or receive paths along with nominal precoding coefficients. Typically, perturbations are interpreted as multiplicative, complex-valued coefficients applied across some coherent bandwidth. The perturbation coefficients may typically have a gain within a range of -3 dB to +3 dB, a phase within a range of -30 degrees to +30 degrees, and are applied over a bandwidth of 0.5 MHz to 50 MHz.10184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00

[0079] For example, when a base station has determined a current precoding OP for transmissions to a particular UE, such a precoder can be written as W( / ), a complex-valued matrix over some frequency band (e.g., the downstream bandwidth being used for the signal transmission). The perturbation operation in this case is the following Hadamard product with perturbation matrix P f)W) ° P^ •OP Precoder Perturbation

[0080] The perturbed precoder may need to be normalized due to power or phase constraints, so the resulting perturbed precoder OP can be written as follows,HW) = ) ° P(Q °Perturbed Precoder OP Precoder OP Perturbation Normalize (optional)

[0081] In this example, W(f), P(f) and N(f) are matrices with a number of rows equal to the number of antenna ports and a number of columns equal to a number of layers:P(y) N f) 6 [num AntennaPorts, num Layers]

[0082] Then, the precoder can be written as:Wl,i( / ) l, num Layers ( / )W) =''''’num Ports, 1 C )um Ports, num Layers CA)

[0083] Herein, / spans some bandwidth, f 6 fc+ [— or some number of physicalresource blocks (PRBs).

[0084] One example construction for the perturbation matrix is:imp i = port(s) of interest, and10k207 ■ 6180j = layer(s) of interest1 otherwise,

[0085] Herein, f spans the first N physical resource blocks (PRBs), where g and (p have units in dB (gain) and degrees (phase), respectively.

[0086] This results in the positively perturbed precoder OPWP(f, +g,+<p = W )op f,+g,+(p),Precoder OP Perturbationl OP Precoder Perturbation

[0087] along with the negatively perturbed precoder OPWP(f, -g,-<p) = W(f) o P(f, -g, -<p Precoder OP Perturbation2 OP Precoder Perturbation11184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00

[0088] Although the above equations show same positive and negative values of gain and phase values for convenience, in general these values may be different in the positive and negative directions.

[0089] FIG. 6 shows additional details of embodiments that perform the calibration based on reference data. As depicted in FIG. 6, reference data intended for reception by UEx (x here represents an index to a particular UE) is depicted in a resource grid 602. Resource grid 604 depicts transmissions for other UEs, or generic data for no UE, uncorrelated to reference data in grid 602 acting as interference to UEx. The two transmissions are precoded using precoder 606 and the resulting combined signal is transmitted using multiple antenna (or transmission points). Graph 608 represents an example of radiation beamwidths used for various signal types that make up the combined signal transmission.

[0090] As depicted in resource grid 602, reference data (denoted by shaded small squares labeled reference data tones) may be multiplexed with other reference signals such as cell specific reference signal CRS (e g., as seen in the dark blocks that are spaced across both time and frequency in the grid) and control transmissions such as a physical downlink control channel (which occupies the first two symbols in LTE). As depicted in resource grid 604, a reference data subframe for interference may comprise reference data on data symbols and blank or zero power resource elements at RE that avoid interference with the reference transmissions from subframe 602.

[0091] As depicted in the beam patterns of graph 608, CRS may be transmitted using an omnidirectional beam pattern. Physical Downlink Control Channel (PDCCH) transmissions may use the same beam pattern as CRS. The reference data transmissions to UEx may have a main lobe in the direction of UEx (estimated direction) and remaining lobes suppressed to a practically negligible amount. The beam pattern of the interfering reference data transmissions to other UEs may include one or more other lobes in the direction of other UEs, with a null point in the direction of UEx.

[0092] For simplicity, the precoder 606 is shown as a 2><2 precoder with precoding coefficients pOO, pOl, plO, pl 1, which in general are complex numbers and also effectuate a phase precoding.

[0093] FIG. 7 shows details of a calibration scheme in which CSI-RS transmissions are used for calibration. As depicted in FIG. 7, CSI-RS intended for reception by UEx (x here represents an12184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00index to a particular UE) is depicted in a resource grid representing a subframe 702. Resource grid 704a depicts self-generated interference or transmissions intended for other UEs, uncorrelated to CSI-RS in grid 702. Resource grid 704b depicts NZP-CSI-RS for interference measurement. NZP-CSI-RS in 704b may be used by other UEs for signal measurement. The two subframe resources are precoded using precoder 706 and the resulting combined signal is transmitted using multiple antennas (or transmission reception points). Graph 708 represents an example of radiation beamwidths used for various signal types that make up the combined signal transmission.

[0094] As depicted in resource grid of subframe 702, CSI-RS transmissions may be used along with PDCCH and CRS transmission, with the remaining RE having zero energy. As depicted in resource grid of subframe 704a, one possible way to simulate interference is to use same RE as subframe 702 for carrying CSI-RS transmissions for other UEs. As depicted in resource grid of subframe 704b, alternatively, or in addition, CSI-RS transmissions for other UEs may be allocated orthogonal or non-overlapping resources than CSI-RS for UEx.

[0095] As depicted in the beam patterns of graph 708, CRS may be transmitted using an omnidirectional beam pattern. PDCCH transmissions may use the same beam pattern as CRS. The reference data transmissions to UEx may have a main lobe in the direction of UEx (estimated direction) and remaining lobes suppressed to a practically negligible amount. The beam pattern of the interfering reference data transmissions to other UEs may include one or more other lobes in the direction of other UEs, with a null point in the direction of UEx.

[0096] For simplicity, the precoder 706 is shown as a 2x2 precoder with precoding coefficients pOO, pOl, plO, pl 1, which in general are complex numbers and also effectuate a phase precoding.

[0097] 10. Discussion of use of data traffic for autocalibration

[0098] As disclosed above, in some embodiments, data transmissions may be used for the autocalibration process. This may be achieved by creating a “virtual UE” which is a virtual user device used for creating inter-beam interference to measure channels and angular positions of UEs. In some implementations, the resource manager may drive the measurement process to cause almost 100% block error rate (BLER) to measure the angular separation. However, for such cases, the underlying communication should not be user data because quality of the user data may suffer due to such a controlled interference. Therefore, embodiments may preferably13184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00use dummy or reference data for cases where BLER is expected to reach a value above a certain minimum acceptable threshold.

[0099] One additional operational challenge faced by the autocalibration process relates to the organization of network-side functions. One particular network-side architecture that has gained traction recently is the use of Central Unit (CU) - distributed unit (DU) configuration for implementation of network side tasks. As further discussed in the next section, channel quality feedback from user devices to network devices may be constrained in such architectures and may not provide satisfactory results for autocalibration due to either elevated use of network bandwidth and / or increased latency of channel calibration that may reduce effectiveness of use of channel quality for optimizing communications.

[0100] 11. Examples of network architectures using resource manager

[0101] FIG. 10 shows an example of a network architecture in which network functions are implemented among three “actors” that are deployed in possibly different geographical locations. The architecture includes a CU, one or more DU, and a resource manager (RM). The CU and DU may be configured to perform conventional functions such as specified in the 3 GPP protocol. It is typical to assign real-time or low-latency functions to the DU, which is typically located in physical proximity of a cell tower or a base station that provides wireless connectivity to user devices, while non-real time functions and interface to core network may be performed at the CU, which may or may not be in a close proximity of the base station.

[0102] The RM may be physically located close to DU or may be implemented in the cloud with communication connectivity with DU (and CU). Some deployments may use a pre-determined interface protocol for communication between RM and DU. One such example is the E2 Service Model (E2SM) protocol used by the Open Radio Access Network (ORAN) consortium which specifies the interface between RM that controls use of certain resources in a radio access network (RAN) corresponding to the DU.

[0103] For example, as depicted in the figure, data traffic may be orchestrated through the CU at the packet data convergence protocol (PDCP) layer level, with QoS flows being established between CU and the radio link control (RLC) layer entities in DUs. The DU is aware of time critical processes such as hybrid automatic repeat request (HARQ) process, random access response (RAR) message, ultra-reliable low latency communication (URLLC) messaging and so14184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00on. A DU scheduler may operate using such information to control resource allocation for transmission by one or more transmitters (Tx) located on the network side. The DU scheduler may also use the scheduling information provided by the RM, with or without modification, for the transmission / reception tasks.

[0104] The DU may communicate with the RM by providing flows report including information such as identities of user devices (UEID) with whom the network is performing communication, quality of service parameters (QOS) such as 5Q1, which represents QOS identifiers used by 5G networks, and a QueueStatus parameter that indicates to the resource manager fullness of various queues set up for data transmissions according to flow partitions.

[0105] The RM may use the information provided by DU and generate a schedule of transmissions / receptions for future time period such as a next slot or a next subframe or a next subframe. The RM may send the scheduling control information to the DU. The information may include a schedule of flow transmissions for next N slots (N may be a number between 1 and 100 or may also set up a semi-periodic flow). The scheduling information may include flow indexes, corresponding physical resource blocks (PRBs), MCS to be used for the transmissions, number of transmission layers, transport block size (TBS) to be used for the transmission and precoding coefficients to be used for the transmissions. In response, the DU reports to the RM actual TBS used for each flow.

[0106] One technical issue with the above-disclosed architecture is the amount of bandwidth and responsiveness latency in the communication between DU and RM. In typical protocols, e.g., the ORAN E2SM protocol, HARQ feedback is not provided by DU to RM on a per-transmitted packet or TB basis in order to reduce computational complexity and bandwidth utilization. The interface may be configured to provide an average count or a total count over a time period (e. g., one or more slots). However, such an arrangement tends to interfere with accuracy and effectiveness of autocalibration task for which, preferably, HARQ feedback for reception of a transmitted data packet should be instantaneously available to the autocalibration process.

[0107] Various techniques are disclosed in the present document to overcome the abovediscussed limitations of the traditional autocalibration operation by using one or more of the following - using actual user data traffic of another user device for autocalibration, using or designating a data radio bearer (DRB) specifically for autocalibration, operating a traffic15184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00generator that generates traffic for autocalibration purpose, e.g., using the DRB and or a logical channel identifier (LCID) on the DRB, requesting and gathering immediate HARQ feedback for the autocalibration traffic.

[0108] 12. Example of O-RAN system

[0109] The characteristics and potential implementations of the MU-MIMO Optimization (mUMO) can be summarized as follows:

[0110] The mUMO enables MU-MIMO in systems with deployed Rus not designed to support MIMO without the need for any modifications in the RU mounted on the towers. This is enabled by employing the automatic calibration and tracking algorithms as part of the mUMO application and some functionality being added to the DL PHY function implemented in the eNB / gNB / O-DU.

[0111] Dynamic Scheduling: the mUMO application makes all the scheduling decisions for non-time-critical flows and provides the scheduling parameters and any precoding information (spatial multiplexing groups of UEs with their resource assignments, precoding coefficients, etc.) to the O-DU for preparing the downlink control information DCIs and transmitting the scheduled flows. This is done by separating the control plane of the DU from the data plane and moving most of the controls to the near real time implementation such as the software function xApp.

[0112] The mUMO can be implemented as an xApp in the Near-RT RIC (as detailed in this document). The mUMO can be co-located with the DU as a separate module. The mUMO can be co-located with the CU as a separate module creating a CU-DU interface similar to split-5. The mUMO can be expanded to support multiple DUs enabling the support for CoMP (cooperative multipoint) and for cell-less MIMO where a precoder applies to antennas from multiple towers.

[0113] 13. Examples of operation as an xApp

[0114] The eNodeB (eNB) / gNB / O-DU sends uplink channel estimates and downlink channel quality measurements, which the mUMO xApp use to predict the downlink channel and quality. The eNB also sends information to the mUMO xApp that conveys downlink traffic activity and priority. The received channel quality measurements are used to predict channel quality estimates and channel attributes which are provided to the RM. The RM utilizes this information to create groupings of UEs that can be scheduled together to provide improved spectral reuse. Precoder coefficients are computed based on the RM and provided over the E2 Interface for use16184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00in the DU. The DU scheduler then uses that information to generate the specific scheduling control messages (DCIs). If a high priority low latency packets need to be transmitted the DU scheduler may replace part of the resources scheduled by the control message with the higher priority packets. A block diagram illustrating the scheduling process is shown in FIG. 10.

[0115] 14. Example embodiments

[0116] Some example embodiments are described in this section with specific reference to ORAN architecture. However, similar techniques may be implemented in other wireless system configurations also.

[0117] FIG. 11 is a block diagram showing an example implementation in which a resource manager is configured to perform scheduling and resource management in a wireless network that includes a gNodeB and evolved packet core (EPC) that provides voice and data packets to various user devices (UE1, UE2, UE3 and UE4) in the network. An RM traffic agent may be configured to operate under direction of the RM and provide a custom DRB traffic that is generated according to the requirements of the RM for autocalibration. In the figure, UE1 is being calibrated and UE4 is used as the interference The gNB may provide custom DRB info to the RM including immediate HARQ feedback. This feedback may be included in one of multiple possible messages (a HarqStatisticsReport message or a ScheduleControlOutcome message). The RM may provide scheduling grants for the autocalibration of UE1 in terms of grants for transmission of the reference data. This information may include LCID of the custom DRB being used for autocalibration. The gNB may be implemented using the CU / DU architecture described herein. A radio resource unit (RRU) may be operational under control of the gNB to communication with UEs such that the autocalibration grant using the custom DRB’s LCID is used to create a multi-user (MU) transmission for UE1 and the interference UE (here, UE4).

[0118] FIG. 12 is a block diagram showing another example configuration of a wireless network in which no EPC is present. Consequently, no RM Traffic generator is used and the autocalibration is performed entirely based on the data flowing through the gNB. In general, a combination of the configurations of both the figures may be used in real networks to serve different UEs. As depicted in FIG. 12, the RM may select one or more UEs based on various selection criteria such as whether sufficient user data traffic is occurring for the UE (e.g., for a17184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00timely and successful completion of the autocal procedure) for causing controlled interference to the target user device for which the autocalibration procedure is being carried out.

[0119] Referring to FIGS. 11 and 12, on the interface between DU and RM, a new information item may be used in a schedule control outcome message that specifies the report being requested from DU. The schedule control outcome may request one or more of the following parameters: a slot information of the schedule control for which the outcome represents status, an indication of the status of the grant, a status of precoding, ACK / NACK / DTX information that includes a list of (previous) resource grants from the RM for which the ACK / NACK / DTX is being reported, a unique identifier of the user device(s) such as a radio network temporary identifier (RNTI) associated with user devices, a system frame number or a slot number information for the slot and a value of the ACK / NACK / DTX. Accordingly, the RM will know exactly which one single specific grant is being ACKed / NACKed.

[0120] In one advantageous aspect, the above-disclosed procedure may be implemented without introducing a new message on the E2SM interface by simply modifying an existing ScheduleControlOutcome message of ORAN specification. In another advantageous aspect, because the ScheduleControlOutcome message is sent from gNB to RM on a one message per slot basis, this scheme does not add any further bandwidth burden to the message exchanges.

[0121] In some embodiments, instead of creating a custom DRB, an existing data bearer may be used for autocalibration. Here, an intermediate function or “glue layer” may be introduced to separately handle reference grant based autocalibration and a regular grant in which no autocalibration is being performed. For transmission using an autocalibration grant, the target UE whose calibration is performed (e.g., UE1 in FIG. 11 and FIG. 12) may be paired with an interfering real UE instead of a virtual UE (e.g., UE4 in FIG. 11 and FIG. 12) and LCID of the actual data bearer is used for the autocalibration transmission. For regular grants, an internet bearer LCID is used. On the receiving side, when RM receives a Schedule Control Outcome with ACK / NACK information, if the underlying grant was autocalibration grant, then autocalibration report is processed. Otherwise, a HARQ statistics report is processed and HARQ counters are increased.

[0122] On the DU side in the gNB, in some embodiments, a similar intelligence is introduced to be able to handle autocalibration and regular LCID traffic and be able to instantaneously report18184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00ACK / NACK in the ScheduleControlOutcome message. Additionally, or alternatively, in some embodiments, such reports may only be generated on a per-transmission basis in a different message such as a HarqStatisticsReport message that reports statistics of HARQ receptions.

[0123] To achieve uninterrupted autocalibration, the RM may ensure that the data bearer being used for autocalibration has sufficient throughput such that autocalibration transmission queue is never empty. To ensure that the autocalibration procedure proceeds in a timely manner, the RM may select user devices that have a sufficient amount of user data traffic at the moment of grant being sent.

[0124] 15. Example methods and implementations of the disclosed technology

[0125] FIG. 8 is a flowchart for an example method 800 of wireless communication. The method 800 includes, at operation 802, determining, by a network device, a current precoding operational point (OP) for transmissions to one or more wireless devices.

[0126] The method 800 includes, at operation 804, performing a first set of measurement transmissions from the network device to the one or more wireless devices, with the first set of measurement transmissions having a first precoding OP that is positively perturbed from the current precoding OP by a first perturbation value.

[0127] The method 800 includes, at operation 806, performing a second set of measurement transmissions from the network device to the one or more wireless devices, with the second set of measurement transmissions having a second precoding OP that is negatively perturbed from the current precoding OP by a second perturbation value.

[0128] The method 800 includes, at operation 808, estimating, based on one or more feedback signals received from the one or more wireless devices in response to the first set of measurement transmissions and the second set of measurement transmissions, a next precoding OP to be used for transmissions from the network device to the one or more wireless devices.

[0129] FIG. 9 is a block diagram representation of a hardware platform 900 which may be used to implement the various methods described in the present document. The hardware platform 900 may be incorporated within a base station or a user device. The hardware platform 900 includes at least one processor 902, a memory 904 and a transceiver circuitry 906. The at least one processor may execute instructions, e. g., by reading from the memory 904, and control the operation of the transceiver circuitry 906 and the hardware platform 900 to perform the methods19184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00described herein. In some embodiments, the memory 904 and / or the transceiver circuitry 906 may be partially or completely contained within the at least one processor 902 (e.g., same semiconductor package).

[0130] The following examples highlight some preferred embodiments and technical solutions that use one or more of the techniques described herein.

[0131] 1. A method of wireless communication (e.g., method 800 in FIG. 8), comprising: (a) determining (802), by a network device, a current precoding operational point (OP) for transmissions to one or more wireless devices; (b) performing (804) a first set of measurement transmissions from the network device to the one or more wireless devices, the first set of measurement transmissions having a first precoding OP that is positively perturbed from the current precoding OP by a first perturbation value; (c) performing (806) a second set of measurement transmissions from the network device to the one or more wireless devices, the second set of measurement transmissions having a second precoding OP that is negatively perturbed from the current precoding OP by a second perturbation value; and (d) estimating (808), based on one or more feedback signals received from the one or more wireless devices in response to the first set of measurement transmissions and the second set of measurement transmissions, a next precoding OP to be used for transmissions from the network device to the one or more wireless devices. Further measurement signal transmissions may be performed by applying the next precoding OP.

[0132] In some examples, operations 804 and 806 correspond to at least one of steps {406, 408, 412} and {406, 410, 414} in FIG. 4, respectively, and operation 808 corresponds to at least one of steps {416, feedback, 402-406}. In other examples, operations 804 and 806 correspond to at least one of steps {504, 506, 510} and {504, 508, 512} in FIG. 5, respectively, and operation 808 corresponds to at least one of steps {514, feedback, 502-504}.

[0133] In some embodiments, the method includes iterating (a) to (d) by setting the next precoding OP to the current precoding OP.

[0134] In some embodiments, the method includes modifying the first perturbation value and / or the second perturbation value according to a rule.

[0135] In some embodiments, the rule specifies that the first perturbation value and / or the second perturbation value are modified according to a change in the one or more feedback20184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00signals during the iterating. In some examples, the one or more feedback signals include the feedback signal in FIG. 4 and / or FIG. 5.

[0136] In some embodiments, the rule specifies that the first perturbation value is equal in magnitude as the second perturbation value.

[0137] Some preferred embodiments or technical solutions that are fully compatible with the LTE protocol include the following:

[0138] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions include reference data transmissions, and wherein the estimating the next precoding OP includes: receiving a first block error rate estimated using a first feedback signal for the first set of measurement transmissions; receiving a second block error rate estimated using a second feedback signal for the second set of measurement transmissions; and estimating the next precoding OP as a function of the first block error rate and the second block error rate.

[0139] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions are performed by adjusting a modulation and coding index according to the one or more feedback signals.

[0140] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions are performed using transmission resources in a data portion of downlink subframes.

[0141] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions comprise multiple-input, multiple-output (MIMO) transmissions in which corresponding beamforming precoding matrices are applied to transmissions to the one or more wireless devices.

[0142] Some preferred embodiments or technical solutions that are fully compatible with the LTE protocol include the following:

[0143] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions include channel state information reference signal (CSI-RS) transmissions, and wherein the estimating the next precoding OP includes: receiving a first channel quality indicator (CQI) and / or a first rank estimated using a first feedback signal for the first set of measurement transmissions; estimating a second CQI and / or a second rank estimated21184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00using a second feedback signal for the second set of measurement transmissions; and estimating the next precoding OP as a function of the first CQI, and / or first rank and the second CQI and / or the second rank.

[0144] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions are performed using CSI-RS transmission resources in downlink subframes.

[0145] In some embodiments, the first set of measurement transmissions and the second set of measurement transmissions comprise multiple-input, multiple-output (MIMO) transmissions in which corresponding beamforming precoding matrices are applied to transmissions to the one or more wireless devices.

[0146] In some embodiments, the CSI-RS transmissions are performed using interference on colocated resource elements (REs).

[0147] In some embodiments, the CSI-RS transmissions are performed using orthogonal resource element (RE) assignments to the one or more wireless devices.

[0148] In some embodiments, the first perturbation value comprises a first gain perturbation value, a first phase perturbation value or a combination thereof.

[0149] In some embodiments, the second perturbation value comprises a second gain perturbation value, a second phase perturbation value or a combination thereof.

[0150] 16. Examples of Resource Manager

[0151] Some wireless systems may deploy a network function called a resource manager (RM) that may be used to coordinate various wireless network operations such as reference signal transmissions, transmitting and receiving channel estimation reports and operating a scheduler that uses the information about channels between the network side transmitter and wireless devices to which a network is providing connectivity.

[0152] In some embodiments, the RM may mitigate the impact of autocalibration process on errors in user data traffic by generating autocal grant with lower frequency than what could cause significant user experience impact. For example, 1 in every 13th data frame sent to UE could be defined as autocal grant. The frequency of occurrence of autocal grants may be configured based on current network traffic compared to maximum network capacity. Furthermore, for every transmission grant that was marked as autocalibration grant, if the corresponding transmission is22184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00NACKed, then the gNB will perform a retransmission of same user data without applying autocalibration related (perturbed) precoding to reduce further errors.

[0153] The RM may be implemented as a software app running on a hardware platform (see, e.g., FIG. 9 and may be integrated with other network-side functions such as traffic scheduling and xApp functionality described herein. The RM may be located near a transmission tower of a cell or may be implemented using computing cloud resources.

[0154] 17. Technical solutions incorporated in some preferred embodiments

[0155] The following technical solutions may be implemented by some preferred embodiments.

[0156] 1. A method of digital communication (e.g., method 1300 depicted in FIG. 13), comprising: configuring (1302) a resource manager to schedule transmissions by interfacing with a radio access network (RAN) according to an application programmer’s interface (API), wherein the RAN is providing wireless connectivity to a plurality of user devices; scheduling (1304) multiple first transmissions from the RAN to one or more target user devices by sending multiple first scheduling messages according to the API; indicating (1306), for each first scheduling message, that the resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme; wherein operational points of the multiple transmissions are perturbed according to the feedback.

[0157] 2. The method of solution 1, including: receiving, the feedback in a response message that identifies identities of target user devices for which the feedback is reported, an identifier of the corresponding transmission grant for which the feedback is reported and a transport block size used for a transmission performed according to the corresponding transmission grant.

[0158] 3. The method of solution 2, including: determining a next operational point for performing next multiple transmissions for autocalibration by perturbing a current operational point used for the transmission performed according to the corresponding transmission grant according to a rule.

[0159] 4. The method of solution 1, further including: scheduling multiple second transmissions from the DU to one or more user devices of the plurality of user devices by sending multiple second scheduling messages according to the API, wherein the multiple second scheduling messages are configured such that feedbacks of transmissions performed according to the23184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00multiple second scheduling messages are received according to a second feedback scheme that is different from the first feedback scheme.

[0160] 5. The method of any of above solutions, wherein the first feedback scheme is implicitly indicated for each first scheduling message based on the API.

[0161] 6 The method of any of above solutions, wherein the first feedback scheme is explicitly indicated in value of a field of the each first scheduling message.

[0162] 7. The method of any of solutions 5-6, wherein the second feedback scheme is implicitly indicated for each first scheduling message based on the API.

[0163] 8. The method of any of above solutions, wherein the second feedback scheme is explicitly indicated in value of the field of the each second scheduling message.

[0164] 9. The method of any of solutions 5-8, wherein the first feedback scheme comprises generating and reporting hybrid automatic repeat request (HARQ) ACK / NACK / DTX information on a per-transmission basis and within a first time budget.

[0165] 10. The method of solution 8, wherein the second feedback scheme comprises hybrid automatic repeat request (HARQ) ACK / NACK / DTX information over multiple transmissions or over a time window and reporting within a second time budget that is greater than or equal to the first time budget.

[0166] 11 The method of any of solutions 5-10, wherein the first feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each first scheduling message.

[0167] 12. The method of any of solutions 5-11, wherein the second feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each second scheduling message.

[0168] 13. The method of any of above solutions, wherein the RAN comprises a distributed unit (DU) that is configured to implement the API.

[0169] 14. The method of any of solutions 1-12, wherein the RAN comprises a base station configured to implement the API and an evolved packet core (EPC) configured to generate the multiple first transmissions.

[0170] 15. A method of digital communication (e.g., method 1400 depicted in FIG. 14), comprising: configuring (1402) a distributed unit (DU) of a radio access network (RAN) to24184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00operate according to an application programmer’s interface (API) with a resource manager, wherein the RAN is providing wireless connectivity to a plurality of user devices; receiving (1404), over the API, multiple first scheduling messages that schedule multiple first transmissions from the RAN to one or more target user devices according to the API; receiving (1406) an indication, for each first scheduling message, that the resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme; and performing (1408) wireless operations according to the each first scheduling message.

[0171] 16. The method of solution 15, including: transmitting, the feedback in a response message that identifies identities of target user devices for which the feedback is reported, an identifier of the corresponding transmission grant for which the feedback is reported and a transport block size used for a transmission performed according to the corresponding transmission grant.

[0172] 17. The method of solutions 15-16, further including: receiving schedules of multiple second transmissions to one or more user devices of the plurality of user devices from multiple second scheduling messages according to the API, wherein the multiple second scheduling messages are configured such that feedbacks of transmissions to be performed according to the multiple second scheduling messages are to be transmitted according to a second feedback scheme that is different from the first feedback scheme.

[0173] 18. The method of any of above solutions, wherein the first feedback scheme is implicitly indicated for each first scheduling message based on the API.

[0174] 19. The method of any of above solutions, wherein the first feedback scheme is explicitly indicated in value of a field of the each first scheduling message.

[0175] 20. The method of any of solutions 18-19, wherein the second feedback scheme is implicitly indicated for each first scheduling message based on the API.

[0176] 21. The method of any of above solutions, wherein the second feedback scheme is explicitly indicated in value of the field of the each second scheduling message.

[0177] 22. The method of any of solutions 18-21, wherein the first feedback scheme comprises generating and reporting hybrid automatic repeat request (HARQ) ACK / NACK / DTX information on a per-transmission basis and within a first time budget.25184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00

[0178] 23. The method of solution 22, wherein the second feedback scheme comprises hybrid automatic repeat request (HARQ) ACK / NACK / DTX information over multiple transmissions or over a time window and reporting within a second time budget that is greater than or equal to the first time budget.

[0179] 24. The method of any of solutions 18-23, wherein the first feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each first scheduling message.

[0180] 25. The method of any of solutions 18-24, wherein the second feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each second scheduling message.

[0181] 26. A wireless communication apparatus comprising one or more processors and a transceiver, wherein the one or more processors cause the wireless communication apparatus to perform the method recited in any of solutions 1 to 25.

[0182] 27. A system comprising a plurality of wireless communication apparatus, each apparatus comprising one or more processors that are configured to implement the method recited in any of solutions 1 to 25.

[0183] In the above solutions, in some embodiments, the first feedback scheme may include immediate feedback in which each transmission from RAN to target user devices immediately receives HARQ feedback according to a protocol (e. g., 3GPP timing requirements for HARQ transmission) and is then reported back by gNB on a per transmission basis.

[0184] In the above solutions, implicit indication of autocalibration may be performed by preassigning specific custom DRB values to autocalibration traffic, e. g, DRB having ID 101 may be exclusively used form autocalibration. This DRB may be operated as a best effort QOS flow.

[0185] In the above solutions, in some embodiments, the second feedback scheme may provide a statistical report of HARQs received for transmissions. The report may include, e.g., average over a time period (e.g., one or more slots).

[0186] In the above solutions, in some embodiments, the RM may implement a glue logic layer that distinguishes the functional use of various flows based on either the implicit or the explicit indication about whether the flows are being used for autocalibration. For example, the glue26184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00layer may be configured to filter specific DRB values and separately generate individual transmission reports for autocalibration parameter perturbation.

[0187] In the above-described solutions, the operational point (OP) may include, for example, a precoder used for communication, a codebook used for communication, other communication parameters such as a modulation and coding index, layer information, and so on. In some solutions, the network device may monitor the progression of the iterative process that includes the above-recited determining-performing-performing-estimating operations, and adjust the accuracy and rate of convergence of the iteration to a stable state by modifying the amount of perturbation introduced by the first and second perturbations. For example, the network device may start an iteration cycle using equal values of perturbation in the positive direction (the first perturbation value) and the perturbation in the opposite direction (the second perturbation value). The network device may then estimate the change in network performance based on the respective feedback received from positive and negative perturbations. In case that the network performance changes are equal or comparable (within a predefined value of each other), the network device may use a same amount of change in both perturbation values in the next iteration. In some embodiments, the network device may reduce a perturbation value in one direction if the measured performance change in that direction is larger than the other direction. For example, smaller changes to feedback may be indicative that the perturbation value has neared a steady-state optimum value in a particular direction, whereas a large change to the network performance may indicate that the perturbation value should be increased because the operational point is not near convergence. In some embodiments, the size calibration perturbations may be a function of a current state of the network. For example, if the network is relatively busy (e.g., if network is reaching capacity above a threshold), smaller values of perturbation may be used to ensure that the iterative calibration does not cause detrimental impacts on the network performance. For example, size of the calibration magnitude and phase perturbations may be inversely proportional to network capacity utilization.

[0188] It will be appreciated by one of skill in the art that various techniques are described to find precoding weights to maximize estimated link capacity, as measured by the UE’s CSI-Report, in the presence of inter-beam interference caused by MU-MIMO. These measurements27184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00may be performed in a fully compatible manner with existing protocols such as LTE with Reference-Data or 5G with CSI-RS transmissions.

[0189] It will also be appreciated that such measurements may be considered to be a link optimization when a single transmitter single receiver pair is used for the measurements (e.g., a single UE as a receiver). In the case that multiple receivers are used (e.g., multiple UEs), the measurements may be considered to be a calibration of the network to achieve a maximal transmission efficiency.

[0190] The disclosed and other embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, which is generated to encode information for transmission to suitable receiver apparatus.

[0191] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup28184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0192] The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASTC (application specific integrated circuit).

[0193] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read -only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices.Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0194] While this patent document contains many specifics, these should not be construed as limitations on the scope of an invention that is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-29184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.

[0195] Only a few examples and implementations are disclosed. Variations, modifications, and enhancements to the described examples and implementations and other implementations can be made based on what is disclosed.30184713813.1

Claims

1. PCT Patent Application Attorney Docket No. 119314.8127.WO00WHAT IS CLAIMED IS:

1. A method of digital communication, comprising:configuring a resource manager to schedule transmissions by interfacing with a radio access network (RAN) according to an application programmer’s interface (API), wherein the RAN is providing wireless connectivity to a plurality of user devices;scheduling multiple first transmissions from the RAN to one or more target user devices by sending multiple first scheduling messages according to the API;indicating, for each first scheduling message, that the resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme;wherein operational points of the multiple transmissions are perturbed according to the feedback.

2. The method of claim 1, including:receiving, the feedback in a response message that identifies identities of target user devices for which the feedback is reported, an identifier of the corresponding transmission grant for which the feedback is reported and a transport block size used for a transmission performed according to the corresponding transmission grant.

3. The method of claim 2, including:determining a next operational point for performing next multiple transmissions for autocalibration by perturbing a current operational point used for the transmission performed according to the corresponding transmission grant according to a rule.

4. The method of claim 1, further including:scheduling multiple second transmissions from a distributed unit (DU) to one or more user devices of the plurality of user devices by sending multiple second scheduling messages according to the API,31184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00wherein the multiple second scheduling messages are configured such that feedbacks of transmissions performed according to the multiple second scheduling messages are received according to a second feedback scheme that is different from the first feedback scheme.

5. The method of claim 4, wherein the first feedback scheme is implicitly indicated for each first scheduling message based on the API.

6. The method of claim 1, wherein the first feedback scheme is explicitly indicated in value of a field of the each first scheduling message.

7. The method of claim 4, wherein the second feedback scheme is implicitly indicated for each first scheduling message based on the API.

8. The method of claim 6, wherein the second feedback scheme is explicitly indicated in value of the field of the each second scheduling message.

9. The method of claim 8, wherein the first feedback scheme comprises generating and reporting hybrid automatic repeat request (HARQ) ACK / NACK / DTX information on a per-transmission basis and within a first time budget.

10. The method of claim 8, wherein the second feedback scheme comprises hybrid automatic repeat request (HARQ) ACK / NACK / DTX information over multiple transmissions or over a time window and reporting within a second time budget that is greater than or equal to the first time budget.

11. The method of claim 10, wherein the first feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each first scheduling message.32184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO0012. The method of any of claims 5-11, wherein the second feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each second scheduling message.

13. The method of any of claims 1-12, wherein the RAN comprises a distributed unit (DU) that is configured to implement the API.

14. The method of any of claims 1-12, wherein the RAN comprises a base station configured to implement the API and an evolved packet core (EPC) configured to generate the multiple first transmissions.

15. A method of digital communication, comprising:configuring a distributed unit (DU) of a radio access network (RAN) to operate according to an application programmer’s interface (API) with a resource manager, wherein the RAN is providing wireless connectivity to a plurality of user devices;receiving, over the API, multiple first scheduling messages that schedule multiple first transmissions from the RAN to one or more target user devices according to the API;receiving an indication, for each first scheduling message, that the resource manager is requesting a feedback of status of a corresponding transmission grant scheduled according to the each first scheduling message according to a first feedback scheme; andperforming wireless operations according to the each first scheduling message.

16. The method of claim 15, including:transmitting, the feedback in a response message that identifies identities of target user devices for which the feedback is reported, an identifier of the corresponding transmission grant for which the feedback is reported and a transport block size used for a transmission performed according to the corresponding transmission grant.

17. The method of claims 15-16, further including:33184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO00receiving schedules of multiple second transmissions to one or more user devices of the plurality of user devices from multiple second scheduling messages according to the API, wherein the multiple second scheduling messages are configured such that feedbacks of transmissions to be performed according to the multiple second scheduling messages are to be transmitted according to a second feedback scheme that is different from the first feedback scheme.

18. The method of any of claims 15 - 17, wherein the first feedback scheme is implicitly indicated for each first scheduling message based on the API.

19. The method of any of claims 15-18, wherein the first feedback scheme is explicitly indicated in value of a field of the each first scheduling message.

20. The method of any of claims 18-19, wherein the second feedback scheme is implicitly indicated for each first scheduling message based on the API.

21. The method of any of claims 15-20, wherein the second feedback scheme is explicitly indicated in value of the field of the each second scheduling message.

22. The method of any of claims 18-21, wherein the first feedback scheme comprises generating and reporting hybrid automatic repeat request (HARQ) ACK / NACK / DTX information on a pertransmission basis and within a first time budget.

23. The method of claim 22, wherein the second feedback scheme comprises hybrid automatic repeat request (HARQ) ACK / NACK / DTX information over multiple transmissions or over a time window and reporting within a second time budget that is greater than or equal to the first time budget.34184713813.1PCT Patent Application Attorney Docket No. 119314.8127.WO0024. The method of any of claims 18-23, wherein the first feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each first scheduling message.

25. The method of any of claims 18-24, wherein the second feedback scheme is implicitly indicated based on a logical channel identifier associated with a data radio bearer associated with the each second scheduling message.

26. A wireless communication apparatus comprising one or more processors and a transceiver, wherein the one or more processors cause the wireless communication apparatus to perform the method recited in any of claims 1 to 25.

27. A system comprising a plurality of wireless communication apparatus, each apparatus comprising one or more processors that are configured to implement the method recited in any of claims 1 to 25.35184713813.1

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