Title - PORT SIGNAL INFORMATION

Abstract

Methods and apparatus for multi-channel communications are disclosed. One method provides precoding, based on a probe reference signal received from a communication device, of reference signal ports in the space and frequency domains, determining pairs of space and frequency domain components where the frequency domain components are arranged in groupings comprising one or more frequency domain components, and enabling the pairing of at least one of the space domain components with at least two groupings of frequency domain components; sending precoding information to the other communication device; and combining the precoding with a precoding notification received in response from the other communication device.Another method provides the sending of the probe reference signal; receiving the precoding information; performing a port selection operation based on the pooled frequency domain component information; and preparing and sending the notification based on the selection operation.

Description

PORT SIGNALING INFORMATION Field This disclosure relates to methods, apparatus, and software products for signaling port information between communication devices. Background Communication sessions can be established between two or more communication devices, such as terminal or user devices, base stations / access points, and / or other nodes. A communication session can be provided, for example, by means of a communication network and one or more compatible communication devices. A communication device on one side of the network provides an access point to the system and is equipped with appropriate signal receiving and transmitting equipment to enable communication, for example, to allow other devices to access the communication system. Communication sessions can include, for example, data communication to carry communications such as voice, video, email, text messages, multimedia, and / or content data, and so on.Non-limiting examples of services provided include two-way or multi-way calling, data communication, multimedia services, and access to a data network system such as the Internet. In a mobile or wireless communication system, at least part of a communication session between at least two devices takes place over a wireless or radio link. Examples of systems 1541335 of 37 Wireless networks comprise terrestrial public mobile networks (PLMN), satellite-based communication systems, and various wireless local area networks, such as wireless local area networks (WLANs). A user can access the broader communication system through an appropriate communication device or terminal. A user's communication device may be referred to as user equipment (UE) or a user device. A communication device is equipped with a signal receiving and transmitting apparatus suitable for enabling communication, for example, access to a communication network or direct communication with other users. A user's communication device can access a carrier provided by a station in a radio access network, such as a base station, and transmit and / or receive communications on that carrier. A feature of modern systems is the ability to operate in multiple paths. A communication device can communicate through multiple paths. Multipath communication can be provided by means of an arrangement known as multiple-input / multiple-output (MIMO). The communication system and associated devices typically operate according to a given standard or specification that defines what the various entities associated with the system are permitted to do and how this should be achieved. Communication protocols and / or parameters to be used for the connection are also usually defined. An example of a communication system is UTRAN (3G radio). Other examples of communication systems include Long-Term Evolution (LTE) of the Universal Telecommunications System's radio access technology. 1541335 of 37 Mobile networks (UMTS) and so-called fifth-generation (5G) or New Radio (NR) networks. 5G is being standardized by the Third Generation Partnership Project (3GPP). Successive versions of the standard are known as Versions (Ver.). In a 3GPP 5G NR standardization, work is underway to further enhance MIMO Channel State Information (CSI) feedback by leveraging the partial uplink / downlink (UL / DL) reciprocity of certain channel statistics. Summary According to one aspect, a method for multi-channel communications is provided, the method comprising: precoding, based on a probe reference signal received from a communication device, reference signal ports in the space and frequency domains by determining pairs of space and frequency domain components where the frequency domain components are arranged in groupings comprising one or more frequency domain components, and enabling a pairing of at least one of the space domain components with at least two groupings of frequency domain components; sending information from the precoding to the other communication device; and combining the precoding with a precoding notification received in response from the other communication device. According to one aspect, a method for multi-channel communications is provided, the method comprising: sending a probe reference signal to a communication device; receiving, in 1541335 of 37 response from the communication device, precoding information comprising reference signal port information in the space and frequency domains defined by pairs of space and frequency domain components where the frequency domain components are arranged in groupings comprising one or more frequency domain components, and a matching of at least one of the space domain components with at least two groupings of frequency domain components is enabled; perform a port selection operation based on the grouped frequency domain component information; and prepare and send a notification based on the selection operation. According to one aspect, an apparatus is provided comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to at least: perform a precoding, based on a probe reference signal received from a communication device, of reference signal ports in the space and frequency domains by determining pairs of space and frequency domain components where the frequency domain components are arranged in groupings comprising one or more frequency domain components, and enable a matching of at least one of the space domain components with at least two groupings of frequency domain components; send information from the precoding to the other communication device;and combine precoding with a notification of; 1541335 of 37 pre-coding received in response from the other communication device. According to one aspect, an apparatus is provided comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to at least: send a polling reference signal to a communication device; receive, from the communication device, precoding information comprising reference signal port information in the space and frequency domains defined by pairs of space and frequency domain components wherein the frequency domain components are arranged in groupings comprising one or more frequency domain components, and a matching of at least one of the space domain components with at least two groupings of frequency domain components is enabled;Perform a port selection operation based on the aggregated frequency domain component information; and prepare and send a notification based on the selection operation. According to a more detailed description, the notification received from the selection communication device includes a precode matrix indication. This combination involves generating a reconstructed precode for use in communications. A portion of a frequency domain compression operation can be performed before sending precoding information, where the communication device receiving the precoding is configured to 1541335 of 37 perform another portion of the frequency domain compression operation. A larger portion of the frequency domain compression operation can be performed on a device performing the precoding than on the device receiving the precoding. A smaller portion of a combined frequency domain compression operation can be performed on a device receiving information from the precoding. Sending precoding information can involve sending a channel status information reference signal based on the precoding for use in selecting channel status information reference signal ports or precoding pairs associated with the ports. A selection of channel status information reference signal ports or precoding pairs associated with the ports can then be performed. A precoding matrix indicator notification can be sent in response, based on the channel status information reference signal ports or precoding pairs selected by the communication device receiving the channel status information reference signal. A communication device can be configured to participate in the calculation of frequency domain components from a restricted subset of a Discrete Fourier Transform codebook for space- and frequency-domain component pairs, and in response to a request for channel status information notification, report information from a selection of non-zero coefficients from a sequence formed by frequency domain components calculated for all space-frequency components measured at the signal ports of 1541335 of 37 reference and an indicator that shows the space-frequency pair and the frequency domain component corresponding to the reported non-zero coefficients. A restricted subset of Discrete Fourier Transform components can be provided. The subset may comprise a window of contiguous components or a set of non-contiguous components from a Discrete Fourier Transform codebook that includes at least the zero component. The restricted subset of DFT components may be the same or different in size or number of components for different groups of space-frequency pairs. As a basis for the operation, a partial reciprocity of grouping delays in channels to and from the communication device can be assumed. The size of the clusters can be determined at least in part based on an estimated cluster delay uncertainty. A precoder weight can be calculated. The calculated precoder weight can be combined with precoder matrix indicator information received from the selection communication device to reconstruct the precoding. Means may also be provided to implement the operations and functions disclosed in this document. A computer software product may also be provided that embodies at least some of the functions described herein. According to one aspect, a computer program comprises instructions for performing at least one of the methods described in the 1541335 of 37 this document. Brief description of the drawings Some aspects will be described below in further detail, by way of example only, with reference to the following examples and the accompanying drawings, in which: Figure 1 illustrates an example of a system where the invention can be put into practice; Figure 2 shows an example of a control device; Figure 3 is a signaling flow diagram between two communication devices; Figures 4 and 5 are flowcharts according to certain examples; Figure 6 illustrates an example of SD and FD components determined for two SD beams based on a received SRS; Figure 7 shows examples for SD and FD component pairings and port selection based on the pairing; and Figures 8, 9, and 10 show yet another example. Detailed description of examples The following description provides an illustrative overview of some possibilities for implementing the invention. Although the description may refer to one or more embodiments in various locations within the text, this does not necessarily mean that each reference is to the same embodiment, or that a particular feature applies only to a single embodiment. Unique features from different embodiments may also be combined to provide other 1541335 out of 37 achievements. Wireless communication systems provide wireless communication to connected devices. Typically, an access point, such as a base station, is provided to enable communication. Different scenarios will be described below using a 3GPP 5G radio access architecture with MIMO capability as an example of an access architecture. However, implementations are not necessarily limited to this type of architecture.Some examples of options for suitable systems are the Universal Mobile Telecommunications System (UMTS) radio access network (UTRAN or E-UTRAN), Long Term Evolution (LTE), LTE-A (LTE Advanced), Wireless Local Area Network (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth®, Personal Communications Services (PCS), ZigBee®, Wideband Code Division Multiple Access (WCDMA), systems using Ultra Wideband (UWB) technology, sensor networks, Mobile Ad Hoc Networks (MANET), cellular Internet of Things (IoT) RAN and Internet Protocol Multimedia Subsystems (IMS), or any combination and further development thereof. Figure 1 shows a wireless system 1 comprising a radio access system 2. A radio access system may comprise one or a plurality of access points, or base stations 12. A base station may provide one or more cells. An access point may comprise any node that can transmit / receive radio signals (e.g., a TRP, a 3GPP 5G base station such as gNB, eNB, a user device such as a UE, and so on). 1541335 of 37 A communications device 10 is located within the service area of ​​radio access system 2, and therefore, device 10 can listen to access point 12. Communications 11 from device 10 to access point 12 are commonly referred to as the uplink (UL). Communications 13 from access point 12 to device 10 are commonly referred to as the downlink (DL). In the example, the downlink is shown schematically to comprise up to four beams per polarization in the space domain (SD). It should be noted that the broader communication system is shown only as cloud 1 and may comprise a number of elements that are not shown for clarity. For example, a 5G-based system may consist of a user equipment (UE), a 5G radio access network (5G RAN) or next-generation radio access network (NG RAN), a 5G backbone (5GC), one or more application functions (AF), and one or more data networks (DN). The 5G RAN may comprise one or more gNodeBs (GNBs) or one or more distributed gNodeB unit functions (GNBs) connected to one or more centralized gNodeB unit functions (GNBs).The 5GC may also include entities such as Network Segment Selection Function (NSSF); Network Exposure Function; Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM); Application Function (AF); Authentication Server Function (AUSF); an Access and Mobility Management Function (AMF); and Session Management Function (SMF). Device 10 can be any suitable communications device adapted for wireless communications. A device of 1541335 of 37 Wireless communication can be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) (e.g., a mobile device such as a mobile phone or what is known as a 'smartphone'), a computer provided with a wireless interface card or other wireless interface installation (e.g., a USB key), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, machine-type communication (MTC) devices, Internet of Things (IoT) communication devices, or any combination thereof. The device may be provided as part of another device. The device may receive signals over an air or radio interface through an apparatus suitable for receiving and may transmit signals through an apparatus suitable for transmitting radio signals.Communications can take place via multiple paths. To enable MIMO communications, devices 10 and 12 are equipped with multi-antenna elements. These are indicated schematically by antenna assemblies 14 and 15. A communications device such as access point 12 or user device 10 is provided with a data processing apparatus comprising at least one processor and at least one memory. Figure 2 shows an example of a data processing apparatus 50 comprising the processor or processors 52, 53 and the memory or memories 51. Figure 2 further shows connections between the apparatus elements and an interface for connecting the data processing apparatus to other device components. 1541335 of 37 The at least one memory may comprise at least one ROM and / or at least one RAM. The communications device may comprise other possible components for use in software- and hardware-assisted execution of tasks for which it is designed, including access control to, and communication with, access systems and other communication devices, and the implementation of the features described in this device positioning document. The at least one processor may be coupled to the at least one memory. The at least one processor may be configured to execute software code appropriate for implementing one or more of the following aspects. The software code may be stored in the at least one memory, for example, in the at least one ROM. The following describes certain aspects of measurement, configuration, and signaling for operations related to multipath or multibeam wireless transmission using 5G terminology. In Frequency Division Duplexing (FDD) systems, full uplink-downlink (UL-DL) channel reciprocity cannot be assumed due to the duplexing distance between the uplink (UL) and downlink (DL) channels. However, partial channel reciprocity can be assumed based on certain properties, such as departure angles (AoD), arrival angles (AoA), and multipath propagation delays. Partial UL-DL reciprocity properties can be considered in the signaling between communicating devices. For example, a gNB can estimate UL probe reference signals (SRS) to acquire information related to 1541335 of 37 delay, such as frequency domain (FD) components, which can be the same as a UE selection made via a DL channel status information reference (CSI-RS) signal. The gNB can then use the selected FD components to further precode beamforming CSI-RS resources that already contain space domain (SD) beams. To transmit multiple sets of FD components along the CSI-RS, more CSI-RS ports need to be configured. This can result in a significant increase in DL CSI-RS resource consumption in proportion to the number of FD components. For example, if each SD beam contains the same number of FD components forming multiple CSI-RS ports, the consumed CSI-RS resources multiply with the increase in precoded FD components.In order to control the total number of CSI-RS ports and the CSI-RS resource capacity, each SD beam can contain a different number of FD components according to the UL probe reference signal (SRS) measurement. The gNB can also indicate to the UE the correlation relationship of CSI-RS ports with SD-FD beam pairs. It has been recognized that it is possible to enhance the MIMO CSI feedback operation by leveraging the partial uplink / downlink (UL / DL) reciprocity of certain channel statistics, such as angle(s) and delay(s). It has already been suggested that enhancing CSI measurement and reporting can be based on an assessment and, if necessary, on specifying the port selection codebook enhancement (e.g., based on a selection of 1541335 of the 37 Type II ports in the existing 3GPP Ver. 15 / 16) where angle and delay information are estimated in the gNB based on an SRS using angle and delay DL / UL reciprocity, and the remaining DL CSI is reported by the UE. This has focused primarily on Frequency Range 1 (FR1) frequency division duplexing (FDD) to achieve a better trade-off between UE complexity, performance, and reporting overhead. For example, the Type II port selection (PS) codebook was enhanced in 3GPP Ver. 16 by introducing a frequency domain (FD) compression operation in the 3GPP Ver. 15 Type II port selection codebook. Such an enhanced Type II PS codebook is described, for example, in section 5.2.2.2.6 of v16.3.0 of 3GPP TS 38.214 of September 2020. Figure 3 shows a signaling flow diagram according to an example between two communication devices, specifically between a UE 10 and a gNB 12. The UE sends SRS 30 to the gNB. The gNB then determines a set of DL precoding vector pairs from the SRS (a set of precoder pairs), taking advantage of partial UL-DL reciprocity. The gNB precodes each CSI-RS port across transmit (tx) antennas and frequency units with one or more pairs from the precoder pair set. The precoded CSI-RS is then sent via message 32 to the UE 10. Subsequently, the UE calculates one or more frequency domain components from a set configured for each precoder pair and prepares a PMI notification. The PMI comprises a selection of precoder pairs and their 1541335 of 37 corresponding combination coefficients. The PMI is signaled by message 34 to the gNB. The gNB combines the PMI with the set of precoder pairs that it previously prepared to obtain a reconstructed precoder for use for data and DMRS communications 36. Figure 4 shows a flowchart of an example operation on a device provided in an access network, for example, access point 12 in Figure 1, to provide more efficient use of resources for signaling information related to reference signal port information for multi-channel communications. In this method, the device receives, at point 100, probe reference signals received from another communication device. The device then performs precoding of reference signal ports in the space and frequency domains, at point 102, by determining pairs of space and frequency domain components based on a grouping of the frequency components.Grouping involves arranging the frequency domain components into groups comprising one or more frequency domain components, such that at least one of the space domain components can be matched with at least two groups of frequency domain components. Precoding information, in 104, can be signaled to the other communicating device and used later, in 106, to prepare a combination of the precoding and a port selection notification received from the other device. The other device can use the pre-coding information 1541335 of 37 signaled to the same in port selection as part of the CSI notification in a reciprocity-based port selection operation. The combination provides a reconstructed precode that can be used for data transmission to the other device. More detailed examples of possible ways to use the pooled precode are provided below. Figure 5 shows a flowchart of an example operation on a device that receives precoding information, for example, device 10 in Figure 1. The device sends a polling reference signal at point 200 to a communication device from which it can then receive precoding information. In response to the sending of the polling reference signal, the device can then receive precoding information from the communication device at point 202. This information comprises reference signal port information in the space and frequency domains, defined by pairs of grouped space and frequency domain components.The frequency domain components are arranged in groups comprising one or more frequency domain components, such that at least one of the space domain components can be paired with at least two groups of frequency domain components. A port selection operation is then performed, in 204, based on the grouped frequency domain component information. After the selection, a notification can be signaled, in 206, based on the selection operation. Examples are given below for calculating, and measurements for preparing, the notification and for using the notification. 1541335 of 37 devices. The following section explains in more detail, as an example, an enhanced codebook structure for signaling port selection channel status information (PS CSI). In one particular example, enhancement can be achieved in the context of frequency domain (FD) compression operations. Compression operations can be moved, at least partially or mostly, from the UE to the gNB. The enhancement is based on the assumption of partial reciprocity of grouping delays on the UL and DL channels and flexibility in the use of frequency domain components. According to one example, a split FD compression operation is provided where some FD component calculations are retained in the UE 10 while some calculations are performed in the gNB 12, instead of an operation where all calculations would be performed in either the UE or the gNB. For example, the current port selection codebook specified in 3GPP Ver. 16 defines that all these calculations are performed in the UE. According to one possibility, the gNB performs a larger portion of the calculations. The flexible solution described herein has a certain advantage because it allows reducing the number of space domain (SD-FD) pairs used by the gNB to precode the CSI-RS ports and, therefore, reduces the reference signaling overhead.The accuracy of the precoder matrix reconstructed from the PMI reported by the UE and the reciprocity-based calculations performed by the gNB itself can also be improved. This is because the UE can be configured to calculate one or more components of the matrix. 1541335 of 37 A Discrete Fourier Transform (DFT) is performed within an uncertainty window for each SD-FD component pair used to precode the CSI-RS ports. The UE can then notify the gNB of FD components that the gNB already knows based on a UL SRS, and the gNB can use this to provide a more accurate estimate. Instead of reporting only one FD component per pre-coded SD-FD pair, the gNB can configure the UE to calculate multiple FD components within a window corresponding to the identified grouping of FD components. The UE can then select which coefficients to report within the grouping. A CSI notification mechanism can be configured to operate such that a gNB pre-codes CSI-RS ports in both the space and frequency domains by pairing space-frequency domain components, where each space domain component is paired with one or more clusters of frequency domain components. A cluster can comprise one or more frequency domain component components. A frequency-domain component of a grouping comprising more than one frequency-domain component can be selected by the gNB to precode the CSI-RS port along with a space-domain component. This can be the first frequency-domain component of the grouping. The UE can be configured to calculate, for example, the first three frequency-domain components for that CSI-RS port. For illustrative purposes, assuming there are N_3 = 13 frequency units, and a grouping for beam 0 consists of the 1541335 of 37 DFT component 6, 7, 8 (there are 13 components in total), the gNB can precode a CSI-RS port with the pair (beam 0, FD component 6) and configure the UE to compute FD component 0, 1, 2. This is equivalent to the gNB using three CSI-RS ports precoded by the pairs (beam 0, FD component 6), (beam 0, FD component 7), (beam 0, FD component 8) since the UE is configured to compute only FD component 0. Due to the properties of the DFT, the gNB can also use a different FD component (e.g., x) for that grouping, even outside the grouping. In that case, the UE is configured to calculate the components of FD x1, x2, x3 such that (x + [x1, x2, x3]) mod N_3 = [6, 7, 8]. The grouping size can be configured based on the uncertainty window. Groupings can be used flexibly. Different groupings can have the same or different numbers of FD components. Each SD beam can be paired with one or more groupings. Different SD beams can have the same or different numbers of groupings. The concept of frequency domain (FD) component grouping can be understood as referring to a grouping that might appear, for example, as a restriction in the FD codebook, configured through a window of a given length. A grouping can comprise one or multiple neighboring FD components selected using gNB, while only the first FD component within the grouping is pre-coded through a CSI-RS port for an SD beam. The UE can be configured to calculate frequency domain components from a restricted subset of a codebook. 1541335 of 37 Discrete Fourier Transform (DFT) for each space-frequency pair. A constraint on the FD components (Wf) that the UE must compute can be provided. The UE then selects which combination coefficients (i.e., FD calculations) to report. The UE can report the value of these 5 coefficients and their position, for example, in a bitmap of size P x ​​1(00) where P is the number of SD-FD pairs and 0(00) is the size of the FD subset. It may not be necessary for the UE to report Wf if the size of this bitmap is sufficiently small (i.e., n^0) is small. The configuration can be provided, for example, by using a Radio Resource Control (RRC) configuration, semi-static configuration such as a Media Access Control Element (MAC CE), or dynamic signaling such as using a Downlink Control Information (DCI) field. A restricted subset of DFT components can be provided, comprising either a window of contiguous components or a set of non-contiguous components from a DFT codebook, including at least component 0. This is the first component in the DFT codebook and is preferred because it provides the average measurement. The restricted subset of DFT components can be the same or different in size, or it can be used for different groups of frequency-space pairs. In response to receiving CSI-RS port information from the gNB, the UE can report back a selection of non-zero coefficients from the sequence formed by the 25 frequency domain components calculated by the UE for all space components 1541335 of 37 frequency measurements at CSI-RS ports and an indicator showing the space-frequency pair and the frequency domain component calculated by UE corresponding to the reported coefficients. More detailed examples are explained with reference to Figures 6 and 7 and the 3GPP Ver. 16 Enhanced Type II codebooks to further illustrate the principles disclosed herein. According to the 3GPP 5G standard, a precoder matrix □ □ x D3, for a layer □ and for all □ □ transmit antennas and 3 Precode Matrix Indicator (PMI) subbands, can be expressed as W(l)= [w® w® w£j = w^w® (1) where the two DFT-based compression operations in the space domain (SD) and frequency domain (FD) are represented by the two bases, Π1 and 1®), respectively. A third operation in the UE extracts the layer representation from the receiving antennas. This operation is not specified, but it usually involves calculating the strongest eigenvectors for each PMI subband, such that Π®), for Π = 0, ... , n3- 1, approximates the strongest channel eigenvector for the subband. The enhancement of FDD CSI notification can be based on an assumption of reciprocity of delays and grouping angles in FDD operations, such that the gNB can estimate a set of dominant SD-FD component pairs and use them to pre-code the CSI-RS ports. This allows some or even most of the SD and FD compression operations to be moved from the UE to the 1541335 of 37gNB. The gNB can estimate the UL channel by measuring the Sounding Reference Signal (SRS) and determining □ SD-FD vector pairs. These are denoted below by (a / 0), □ / / / , where □ / / ) is a □ □ x 1 vector and □ / 0) is a D3x 1 vector containing the precoding weights in the space and frequency domains, respectively. The index □ = 0, ... , □ - 1 is associated with the SD-FD pair. The SD component index is □ □ e {0, 1, ... , □ - 1}, where □ is the number of SD beams. The FD component index is Ene {0, 1, ... , D^0)- 1}, where 0(°°) indicates the number of FD components. It should be noted that, in general, any two pairs can have the same SD component index or FD. Let W(UL) _ Γ (UL) (UL) (UL) 1 i -[vío ,vh .....^íp-t](2) be a matrix x whose columns represent the weight vector used to beamform the CSI-RS ports along the space domain, and ' - \a ·νy™] with(3) (UL)=Γ (UL) (UL) (UL)1yfp [yfp. 0'yfp, 1' ... ' T / p^ — l] be a J3x J matrix whose L-th column, u / D), contains the weights applied to the L-th CSI-RS port along the L3 frequency units. Some of the vectors in ( ) and ( ) may be repeated, although all pairs (j / d), ( / , for u - 0, ... , u - 1, nevertheless, are distinct. Figure 6 illustrates an example where the channel decomposition of 1541335 of 37 UL in □ = 2 spatial beams (beam 0, beam 1) and 1(00) = 6 FD components. The SD components and FD components can be determined in the gNB based on SRS measurements. The FD components can be extracted from a DFT codebook. A beam representation in the transform domain exposes the dominant grouping delays measured in that beam. The double-headed arrows indicate an uncertainty associated with the pooling delay estimate in the gNB. This uncertainty can be caused, for example, by a mismatch in the UL-DL delay reciprocity, degradations in the UL channel estimate, and aging effects due to the time lag between the UL channel estimate from the SRS and the DL channel estimate from a CSI-RS. Furthermore, applying a DFT vector as precoding weights across the frequency units of a CSIRS port beamforming a certain spatial beam corresponds to a circular shift of the beam representation in the transform domain. This is illustrated on the left side of Figure 7, where examples are given for the matching of SD and FD components for the example in Figure 6. More specifically, a possible grouped matching of SD-FD components in the gNB is presented. The groupings are defined by the 20 windows. Then, the pair selection in the UE is presented in the table on the right. In this case, the UE is configured to calculate Γ(αα) = 2 FD components (0 and 1) for each SD-FD pair. The shaded cells correspond to selected SD-FD pairs, for which a non-zero coefficient can be reported. 1541335 of 37 In the example in Figure 7, the gNB forms FD component groupings based on window 20. Note that the lowest row, y4, refers to the FD component numbers in Figure 6, which illustrates the gNB's FD component estimation based on the UL channel measurement. The corresponding estimate at the UE may be different and have a strong component at y5 for beam 1, for example. The window size can be defined taking uncertainty into account. The gNB can match each spatial beam with the first representative component of the groupings. The example has 3 groupings for beam 0 and 3 groupings for beam 1. In total, the gNB has selected 6 from 0 0(°°) = 12 possible combinations. For CSI-RS port precoding, each grouping can be moved to FD 0 location, precoding the port with the first FD component of the grouping. It should be noted that a different number of groupings, FD components per grouping, and beams can be selected. It can be assumed, for reasons of simplicity, that there is a one-to-one correlation between the distinct SD-FD component pairs and the πααα-□□ ports, such that □□□□-□□ = Ί. The CSI-RS sequences used throughout the PRBs can be entered into the Bandwidth Part (BWP) configured for a CSI notification: {do, ai, ... , aPcs¡-RS-i} with (4)ap =[ap, 0,ap, 1, ... ,ap,NSfB-1] With u = [□ / □□□□] the frequency unit is indicated (i.e., the 1541335 of 37 Precoding Matrix Indicator (PMI) subband corresponding to PRB □ , where □ □□□ is the number of Physical Resource Blocks (PRBs) in a frequency unit. The signal received on PRB □ by a UE equipped with □ □ receiving antennas, on the CSI-RS ports, □ □ , after code demultiplexing if CDM was used, can be written as a □ □ x □ matrix, F k = H^M^diag (w^OA ... ,wfÍUpQ- i, t)diag(ao, k, ... ,aP- i,k) +Nk (5) = H Adiag^rk) +Nk iii , . „ , ii I-XI ii where is the DL channel x matrix for the PRB , is the effective DL channel x matrix seen by the UE through the beamforming CSI-RS ports and □ □ is the additive noise. The CSI-RS measurements in the PRB □ are given by the matrix Hk = diag(cr, k)Yl (6) and the □ x □ □ matrix of measurements for each pair of SD - FD components and receiving antenna, in the sub-band, can be obtained, for example, by averaging the PRBs in that sub-band ^t = [^t, 0, ^t, 1, ... , ^t.Nr-1] =Σk: [k / n£|bJ = t H'k / NPRB.(7) As noted previously, the number of SD-FD component pairs, Π, can be assumed to be equal to the number of CSI-RS ports, nDDD-D□, such that there is a one-to-one correlation between ports and SD-FD component pairs. However, a many-to-one correlation can also be adopted to reduce the DL reference signal skew, in which case the above expressions are modified to include the correlation and decorrelation operations. Figures 8, 9, and 10 illustrate examples of many-to-one correlation operations. 1541335 of 37 are described in more detail later. A powered port selection codebook structure can be considered based on the equation [Error! Reference source not found.], where the codebook for 1 / °) is associated with SD-FD pair selection, while Lg™) = [□fDD), ... ,f_. / | corresponds to a network-restricted DFT codebook limited to the first 0(°°) components, where 0(°°) can be very small. A case of special interest is for 0(°°) = 1, such that WfDL)(8) In this case, a UE only calculates the FD 0 component, and no DFT operation is required from the UE in the frequency domain. In this case, the PMI reported by the UE is the same for all sub-bands because the precoder variations in the frequency domain can be determined in the gNB. In the example in Figure 7, values ​​of nfDD) greater than 1 are considered. In this case, some of the precoder frequency variations can be determined in the UE as well as the gNB. The case of ΠfDD) = r3 may correspond to the enhanced Type II PS codebook of 3GPP Ver. 16, where there is no restriction on the FD codebook in the UE and FD precoding of the CSI-RS ports in the gNB is not required. In the example in Figure 7, the SD-FD component pairing in the gNB and pair selection in the UE are shown for paran(ΣΣ) = 2. Setting the parameter nfDD) to a value greater than 1 can be beneficial in reducing the number of SD-FD pairs and, therefore, the 1541335 of the 37 CSI-RS ports required. The accuracy of the reported PMI can also be improved by allowing the UE to select the best delay or delays (i.e., FD components) within a length uncertainty window □(DD), for each FD component identified by the gNB. When the parameter n^0) > 1, the PMI reported by the UE may differ for different sub-bands. The UE can contribute to the operation by determining the precoder's frequency domain variations. The gNB receives these in the PMI notification and can then combine them with the precoder variations at the frequency calculated by the gNB based on the partial reciprocity assumption. SD-FD pairs can be selected by the UE from among possible □ □(DD) pairs, where the effective FD component calculated by the UE for the pair (^α™), ^( / °)) is, in general, the combination of UL and DL FD components, Dg™) or Lg00), for □ = 0, ... , D(dd)- 1. In the case Π(□□) = i ,() or Ί?α)= π?0) . The selected SD-FD pairs, symbolized by the shaded cells in Figure 7, also correspond to the reported non-zero coefficients. In the example, the UE selects five dominant or strongest pairs. In order to determine the linear combination coefficients for each SD-FD and receiving antenna pair, the UE can form a Ϡ x n3 matrix, , (□) u2, for L = 0, ... , _ln- 1 W ír)= [h'„,r,h'K.....^-,.,-] (9) and calculate the coefficients applying Error! Reference origin not found. a Error! Reference origin not found.. This produces the vector x 1 (or the matrix xn(DD), in general, for Ί(αα)> 1) 1541335 of 37 «3-1 V) urlr^ (07) ill ^2 = w2 y0 = Σht'rt =0 (10) In this phase, the UE can determine the strongest spatial layers from linear combinations of the receiving antennas. This operation can be performed by applying a single singular value decomposition r(0) ~(1) -v - 1)] (SVD) to the matrix □ x □□, Id2,22, ... , □2I, (or matrix C d(Da)x □ □ ) and obtaining the strongest left eigenvectors: Γ~,(0) ~,(1) ~,(»ri)l ^^° r~(1) ~(2) ~(v)l . .. 1^2 ,^2 , ... ,W2 ]-^\W2 ,W2 , ... ,w2J, v < Nrcon In the 3GPP Ver. 16 Enhanced Type II Codebooks (CBs), this layer extraction is usually done per subband, before applying FD compression. However, when FD precoding is applied to the CSI-RS ports, the phase relationship between subbands cannot be easily preserved if eigenvectors are extracted before summation. Eigenvectors are determined in each subband with a phase uncertainty, which can be adjusted, for example, to remove phase jumps between subbands before FD compression. However, when FD precoding is applied to the gNB, these phase adjustments in the UE would change the phase relationships between subbands and, in practice, change the effect of the precoder weights applied at the frequency in the gNB. After layer processing, the UE can select a subset of the strongest non-zero coefficients from among the ~(1) . . -22) . _ ..... coefficients in Σ2 for layer 1, Σ2 for layer 2, etc. This selection of 1541335 of 37 non-zero linear combination coefficients can be free within the vector □ x 1 of coefficients for layer □ (or, in general, within a matrix □ x 0(°°) of coefficients) and the corresponding bitmap also indicates the selection of SD - FD pairs. Regarding the presence of restriction in the selection of SD - FD pairs, in 3GPP Ver. 15 / 16, port selection is restricted to a group of consecutive ports, with groups of ports separated by □ < □ ports, and with the same ports used for both polarizations. Conversely, 3GPP Ver. 17 allows free or unrestricted selection, with the selection extended to the set of SD-FD pairs, which can be larger than the number of ports. In view of the PMI reconstruction and the reciprocity precoder representation, it is noted that, if n^0) = 1, a UE reports only one FD 0 component from among the selected SD-FD pairs. Let UOD, UÍQ, ... , UD_ÍQ be the indices of the L SD-FD pairs selected for layer u , with UQ ne {0, ... , L - 1}. Let Jg0) be the linear combination coefficient corresponding to the SD-FD pair , yu (°0) the selection vector consisting of all zeros with a one in position ua, □ UQ Q. The precoder ux J3 matrix for layer L, reported by the UE in the PMI, can be expressed as L-1 Wv = Σ -c©A^kj,tkj,i'° i = n (12) The JDx u3 reciprocity precoder that combines the weights calculated by the gNB and taking into account the PMI, can be expressed as 1541335 of 37 L-1HL-1 (0 = Σv(^) (^ (o¢^)) = Σ (t)v™ / ^.(13)RZjlkj,iko\ fkj,i0 / ZjkJAlkj,ifkj,ij = 0j = 0 In the general case illustrated in Figure 7, with m(dl> 1, let 0(°) be the linear combination coefficient corresponding to the SD-FD pair and the FD component calculated by UE 0. The precoder matrix □ x 03 for layer □, reported by the UE in the PMI, can be expressed as L-1 M(dl^-1 ' ΣνΟ Σ < mj = 0 m = 0 (14) Therefore, the reciprocity precode □ □ x 03 that combines the weights calculated by the gNB and taking into account the PMI, can be expressed in this scenario as L-1 M(dl)-1wR^^ Σ ^- mffo / mm^. j = 0 m = 0 (15) It should be noted that, although the above examples have been described with reference to a user equipment (UE) and a gNB, similar principles can be applied to any device capable of multi-beam communications. According to one possibility, multiple precoding pairs are correlated on the same CSI-RS ports. This is another way to reduce the number of ports that need to be notified. In this case, it is possible to use code division multiplexing (CDM) for this pair multiplexing to a single port, taking advantage of the fact that each frequency unit consists of multiple PRBs that are precoded by the same frequency component weight. An example of the many-to-one correlation operation between SD-FD precoding pairs and 1541335 of 37 The PCSI-RS < P ports of CSI-RS are illustrated in Figure 8, which shows a functional block diagram of the operations performed in the gNB. The inverse one-to-many decorrelation operation takes place in the UE, as illustrated in the functional block diagram of the UE operations in Figure 9. Figure 10 shows an example of this many-to-one correlation. In the example, the bandwidth portion (BWP) configured for a CSI notification is divided into N3 frequency units, and each frequency unit consists of NpBB = 4 PRBs. The example shows how a CDM sequence of length 4 can be used to accommodate two SD-FD pairs on a CSI-RS port, for a generic frequency unit t. The operation is repeated for all frequency units with different frequency component weights. Up to NpBB SD-FD pairs can be multiplexed on the same port.It should also be noted that the illustration in Figure 10 does not show other possible operations in the generation of the CSI-RS port sequence, such as multiplying the precoding weights by the CSI-RS sequence for port , correlating the sequence with resource elements (REs) within the PRBs, and multiplying by another CDM sequence associated with correlating the port sequence with REs. These operations are standard procedures in generating a CSI-RS transmission sequence and are not affected by the precoding-to-port pair correlation shown in Figure 10. A multi-channel communications device may comprise means for pre-coding, based on a signal of 1541335 of 37 probe reference received from a communication device, reference signal ports in the space and frequency domains determining pairs of space and frequency domain components wherein the frequency domain components are arranged in groupings comprising one or more frequency domain components, and a matching of at least one of the space domain components with at least two groupings of frequency domain components is enabled; means for sending precoding information to the other communication device; and means for combining the precoding with a precoding notification received in response from the other communication device. Another multi-channel communication device may comprise means for sending a probe reference signal to a communication device; means for receiving, in response from the communication device, precoding information comprising reference signal port information in the space and frequency domains defined by pairs of space and frequency domain components, wherein the frequency domain components are arranged in groupings comprising one or more frequency domain components, and a pairing of at least one of the space domain components with at least two groupings of frequency domain components is enabled; means for performing a port selection operation based on the grouped frequency domain component information; and means for preparing and sending a notification based on the selection operation. 1541335 of 37 It should also be noted that, while the foregoing describes exemplary embodiments, several variations and modifications can be made to the disclosed solution without departing from the scope of the present invention. Different features can be combined from different embodiments. Therefore, the embodiments may vary within the scope of the appended claims. In general, some embodiments may be implemented in special-purpose hardware or circuitry, software, logic, or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device, although the embodiments are not limited to these.Although various realizations can be illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it is well understood that these blocks, devices, systems, techniques, or methods described herein can be implemented in, as non-limiting examples, hardware, software, firmware, special-purpose circuits or logic, general-purpose hardware or controller, or other computer devices, or some combination thereof. The implementations can be carried out using software stored in memory and executable by at least one data processor of the entities involved, or using hardware, or a combination of software and hardware. Furthermore, it should be noted that any of the above procedures may represent stages of 1541335 of 37 program, or functions, blocks, and interconnected logic circuits, or a combination of program steps and functions, blocks, and logic circuits. Software can be stored on physical media such as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disks or floppy disks, and optical media such as, for example, DVDs and data variants thereof, CDs. Memory can be of any type suitable to the local technical environment and can be implemented using any appropriate data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. Data processors can be of any type suitable to the local technical environment and may include one or more general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), gate-level circuits, and processors based on multi-core processor architecture, as non-limiting examples. Alternatively or additionally, some implementations can be implemented using circuitry. The circuitry can be configured to perform one or more of the previously described method functions and / or procedures. This circuitry can be provided in the network entity and / or the communications device and / or a server and / or a device. As used in this application, the term circuitry may refer to one, more, or all of the following: (a) hardware-only circuit implementations (such as 1541335 of 37 implementations in analog and / or digital circuitry only); (b) combinations of hardware and software circuits, such as: (i) a combination of analog and / or digital hardware circuit or circuits with software / firmware and (ii) any portions of a hardware processor or processors with software (including digital signal processor or processors), software and memory or memories working together to make the communications device and / or the device and / or the server and / or the network entity perform the various functions described above; and (c) hardware circuit or circuits and / or processor or processors, such as a microprocessor or microprocessors or a portion of a microprocessor or microprocessors, that require software (for example, firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this application, including in any claim. 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 a portion of a hardware circuit or processor and its accompanying software and / or firmware. The term circuitry also covers, for example, an integrated device. It should be noted that, although implementations have been described in relation to certain architectures, similar principles can be applied to other systems. Therefore, although certain implementations have been described above by way of example with reference to certain illustrative network architectures, similar principles can be applied to other systems. 1541335 of 37 wireless technologies, standards, and protocols, the features described herein may be applied to any suitable form of systems, architectures, and devices other than those illustrated and described in detail in the preceding examples. It is also noted that 5 different combinations of different embodiments are possible. It is further noted herein that, while the foregoing describes illustrative embodiments, there are several variations and modifications that may be made to the disclosed solution without departing from the spirit and scope of the present invention. 1541335 of 37 PABLO SCHMUKLER - 20117733352 Digitally signed by PORTALTRAM ITES - INPI Date: 2021.10.18 14:05:52 -03:00 Reason: Digitally Signed by the INPI Location: Buenos Aires, Argentina 1541335

Claims

1. A method comprising: sending a sounding reference signal to a base station; receiving, in response to the sounding reference signal from the base station, pre-coded reference signals in the space and frequency domains: - wherein the frequency domain components are arranged in groupings, each grouping comprising frequency domain components within a window of a given length, and - the precoding of a reference signal port comprising matching one of the space domain components with a frequency domain component of a grouping; receiving a configuration indicating a number of frequency domain components to be computed for a reference signal port, the number of frequency domain components being within a window corresponding to the grouping associated with the reference signal port;performing a port selection operation based on the received pre-coded reference signals; and preparing and sending a notification to the base station based on the selection operation. 19 Claims follow;