Improve communication efficiency

Abstract

A method at a user equipment is provided, the method comprising: receiving transmissions on two different polarizations from a network over a wireless channel (300); determining a plurality of coefficients associated with a precoding matrix based on received channel measurements, wherein the coefficients at least partially define a combining matrix (302); selecting coefficients among the coefficients of a weaker polarization, the selected coefficients being reference coefficients for the weaker polarization (304); determining a first indicator and a second indicator for the reference coefficients, wherein the first indicator indicates a location of the reference coefficient in the combining matrix and the second indicator comprises an amplitude value associated with the reference coefficient (306); and reporting the first indicator and the second indicator to the network (308).

Description

Technical Field

[0001] Various example embodiments generally relate to improving communication efficiency. Background Art

[0002] Precoding can be performed at the transmitter using multiple antennas. Performing precoding can adjust the signal to be transmitted into a varying form that the signal may be exposed to when passing through the radio channel between the transmitter and the receiver. In order to perform appropriate precoding, precoding feedback can be used. Summary of the invention

[0003] According to some aspects, the subject matter of the independent claims is provided. Some other aspects are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present invention will be described in more detail below with reference to embodiments and accompanying drawings, in which:

[0005] Figure 1 shows a communication network in which embodiments may be applied;

[0006] Figure 2A and Figure 2B An example matrix and bitmap are shown, respectively;

[0007] Figure 3 and Figure 4 A method according to some embodiments is shown;

[0008] Figure 5 illustrates a signaling flow diagram according to an embodiment; and

[0009] Figure 6 and Figure 7 An apparatus according to some embodiments is illustrated. DETAILED DESCRIPTION

[0010] The following embodiments are exemplary. Although the specification may refer to "one", "a kind" or "some" embodiments at several locations in the text, this does not necessarily mean that the same embodiment (s) is referenced each time, or that a particular feature only applies to a single embodiment. Individual features of different embodiments may also be combined to provide other embodiments.

[0011] The described embodiments may be implemented in a radio system, such as a wireless system including at least one of the following radio access technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile Communications (GSM, 2G), GSM EDGE Radio Access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunications System (UMTS, 3G) based on basic Wideband Code Division Multiple Access (W-CDMA), High Speed ​​Packet Access (HSPA), Long Term Evolution (LTE), Advanced LTE, and Enhanced LTE (eLTE). The term "eLTE" here refers to the evolution of LTE connected to a 5G core. LTE is also known as Evolved UMTS Terrestrial Radio Access (EUTRA) or Evolved UMTS Terrestrial Radio Access Network (EUTRAN). The term "resource" may refer to a radio resource, such as a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a subcarrier, a beam, etc. The term "transmit" and / or "receive" may refer to sending and / or receiving wirelessly via a wireless propagation channel on a radio resource.

[0012] However, the embodiments are not limited to the system / RAT given as an example, but those skilled in the art may apply the present solution to other communication systems that provide the necessary attributes. An example of a suitable communication system is a 5G system. The 3GPP solution for 5G is called New Radio (NR). 5G has been envisioned to use multiple-input multiple-output (MIMO) multi-antenna transmission technology, deploy more base stations or nodes (the so-called small cell concept) than the current LTE network, including macro sites that operate in collaboration with smaller local access nodes, and may also adopt various radio technologies for better coverage and enhanced data rates. 5G will most likely include more than one radio access technology / radio access network (RAT / RAN), each optimized for a specific use case and / or spectrum. 5G mobile communications can have a wider range of usage scenarios and related applications, including video streaming, augmented reality, different data sharing methods, and various forms of machine-type applications, including vehicle safety, different sensors, and real-time control. 5G is expected to have multiple radio interfaces, namely below 6GHz, centimeter wave (cmWave) and millimeter wave (mmWave), and can be integrated with existing traditional radio access technologies such as LTE.

[0013] The current architecture in LTE networks is distributed in the radio and concentrated in the core network. Low-latency applications and services in 5G need to bring content to the vicinity of the radio, which leads to local interruptions and multi-access edge computing (MEC). 5G enables analysis and knowledge generation to occur at the data source. The method requires the use of resources that may not be continuously connected to the network, such as laptops, smart phones, tablet computers and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content very close to cellular subscribers for faster response time. Edge computing covers a wide range of technologies (such as wireless sensor networks, mobile data acquisition, mobile signature analysis, collaborative distributed peer-to-peer ad hoc networks and processing) and can also be classified as local cloud / fog computing and grid / net computing, dew computing, mobile edge computing, micro-cloud, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (large-scale connection and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analysis, time-critical control, health care applications). Edge cloud can be brought into RAN by leveraging network function virtualization (NVF) and software defined networking (SDN). Using edge cloud can mean that access node operations are at least partially implemented in a server, host or node that is operably coupled to a remote radio head or base station that includes radio components. Network slicing allows multiple virtual networks to be created on top of a common shared physical infrastructure. The virtual networks are then customized to meet the specific needs of applications, services, devices, customers or operators.

[0014] For 5G networks, it is envisioned that the architecture may be based on a so-called CU-DU (central unit-distributed unit) split, where one gNB-CU controls several gNB-DUs. The term "gNB" in 5G may correspond to an eNB in ​​LTE. The gNB(s) may communicate with one or more UEs 120. A gNB-CU (central node) may control multiple spatially separated gNB-DUs, acting at least as a transmit / receive (Tx / Rx) node. However, in some embodiments, a gNB-DU (also referred to as DU) may include, for example, a radio link control (RLC), a media access control (MAC) layer, and a physical (PHY) layer, while a gNB-CU (also referred to as CU) may include layers above the RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC), and an Internet Protocol (IP) layer. Other functional splits are also possible. It may be assumed that the skilled person is familiar with the OSI model and the functions within each layer.

[0015] Some other technological advances that may be used are Software Defined Networking (SDN), Big Data and All-IP, to mention just a few non-limiting examples. For example, network slicing can be in the form of a virtual network architecture that uses the same principles behind Software Defined Networking (SDN) and Network Function Virtualization (NFV) in fixed networks. SDN and NFV can deliver greater network flexibility by allowing the traditional network architecture to be divided into virtual elements that can be linked (also through software). Network slicing allows the creation of multiple virtual networks on a common shared physical infrastructure. The virtual networks are then customized to meet the specific needs of applications, services, devices, customers or operators.

[0016] Multiple gNBs (access points / nodes, each gNB includes a CU and one or more DUs) can be connected to each other via an Xn interface, and the gNBs can negotiate through the Xn interface. The gNB can also be connected to the 5G core network (5GC) through the next generation (NG) interface, and the 5G core network can be the 5G equivalent of the LTE core network. This 5G CU-DU split architecture can be implemented using a cloud / server, so that the CU with higher layers is located in the cloud, and the DU is closer to or includes the actual radio unit and antenna unit. There are similar plans underway for LTE / LTE-A / eLTE. When both eLTE and 5G will use a similar architecture in the same cloud hardware (HW), the next step may be to combine software (SW) so that one common SW controls both radio access networks / technologies (RAN / RAT). This may then implement new ways to control the radio resources of the two RANs. In addition, it is possible to have the following configuration: the complete protocol stack is controlled by the same HW as the CU and processed by the same radio unit as the CU.

[0017] It should also be understood that the distribution of labor between core network operations and base station operations may be different from LTE, or even non-existent. Some other technological advances that may be used are big data and all-IP, which can change the way networks are built and managed. 5G (or New Radio, NR) networks are designed to support multiple layers, where MEC servers can be placed between the core network and the base station or Node B (gNB). It should be understood that MEC can also be applied to 4G networks.

[0018] 5G can also make use of satellite communications to enhance or supplement the coverage of 5G services, for example by providing backhaul. Possible use cases are for machine-to-machine (M2M) or Internet of Things (IoT) devices or for providing service continuity for passengers in vehicles, or ensuring service availability for critical communications and future railway / maritime / aeronautical communications. Satellite communications can make use of geosynchronous orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (i.e. systems with hundreds of (nano) satellites deployed). Each satellite in a mega-constellation can cover several satellite-enabled network entities creating ground cells. Ground cells can be created by ground relay nodes, or by gNBs on the ground or in satellites.

[0019] Embodiments may also be applied to narrowband (NB) Internet of Things (IoT) systems, which can enable the use of cellular telecommunications bands to connect a wide range of devices and services. NB-IoT is a narrowband radio technology designed for the Internet of Things (IoT) and is one of the technologies standardized by the 3rd Generation Partnership Project (3GPP). Other 3GPP IoT technologies that are also suitable for implementing embodiments include machine type communication (MTC) and eMTC (enhanced machine type communication). NB-IoT pays special attention to low cost, long battery life, and enabling a large number of connected devices. NB-IoT technology is deployed "in-band" in the spectrum allocated to Long Term Evolution (LTE) - using resource blocks within normal LTE carriers, or deployed in unused resource blocks within LTE carrier protection bands - or "standalone" for deployment in dedicated spectrum.

[0020] Figure 1 An example of a communication system to which an embodiment of the present invention can be applied is illustrated. The system may include a control node 110 providing a cell 100. For example, each cell may be, for example, a macro cell, a micro cell, a femto cell, or a pico cell. In another viewpoint, the cell may define a coverage area or a service area of ​​the access node 110. The control node 110 may be an evolved node B (eNB) such as in LTE and LTE-A, an ng-eNB such as in eLTE, a gNB of 5G, or any other device capable of controlling wireless communications and managing radio resources within a cell. The control node 110 may be referred to as a base station, a network node, or an access node.

[0021] The system may be a cellular communication system consisting of a radio access network of access nodes, each access node controlling one or more corresponding cells. The access node 110 may provide wireless access to other networks such as the Internet to user equipment (UE) 120 (one or more UEs 120, 122). The wireless access may include downlink (DL) communication from the control node 110 to UEs 120, 122 and uplink (UL) communication from UE 120 to the control node 110. Additionally, one or more local access nodes may be arranged in the control area of ​​a macrocell access node. The local access node may provide wireless access in a subcell that may be included in a macrocell. Examples of subcells may include microcells, picocells and / or femtocells. Typically, a subcell provides a hotspot in a macrocell. The operation of the local access node may be controlled by an access node, and the subcell is provided under the control area of ​​the access node.

[0022] In the case of multiple access nodes in a communication network, the access nodes can be connected to each other using an interface. The LTE specification refers to this interface as the X2 interface. For IEEE802.11 networks (i.e., wireless local area networks WLAN, WiFi), a similar interface Xw can be provided between access points. The interface between an eLTE access point and a 5G access point can be referred to as Xn. Other communication methods between access nodes are also possible.

[0023] The access node 110 may also be connected to the core network of the cellular communication system via another interface. The LTE specification specifies the core network as an evolved packet core (EPC), and the core network may include a mobile management entity (MME) and a gateway node. The MME may handle the mobility of a terminal device in a tracking area containing multiple cells, and handle the signaling connection between the terminal device and the core network. The gateway node may handle data routing in the core network, and data routing to / from the terminal device. The 5G specification specifies the core network as a 5G core network (5GC), and the core network may include an advanced mobile management entity (AMF) and a gateway node. The AMF may handle the mobility of a terminal device in a tracking area containing multiple cells, and handle the signaling connection between the terminal device and the core network. The gateway node may handle data routing in the core network, and data routing to / from the terminal device.

[0024] UE generally refers to a portable computing device, including wireless mobile communication devices operating with or without a subscriber identity module (SIM), including but not limited to the following types of devices: mobile stations (mobile phones), smart phones, personal digital assistants (PDAs), mobile phones, devices using wireless modems (alarm or measurement equipment, etc.), laptop and / or touch screen computers, tablet computers, game consoles, notebooks, vehicle-mounted devices, and multimedia devices.

[0025] In the case where there are multiple access nodes in the communication network, the access nodes can be connected to each other using an interface. The LTE specification refers to this interface as the X2 interface. For IEEE802.11 networks (i.e., wireless local area networks WLAN, WiFi), a similar interface Xw can be provided between access points. The interface between the eLTE access point and the 5G access point can be referred to as Xn. Other communication methods between access nodes are also possible. The access node 110 can also be connected to the core network of the cellular communication system via another interface. The LTE specification specifies the core network as an evolved packet core network (EPC), and the core network may include a mobile management entity (MME) and a gateway node. The MME can handle the mobility of the terminal device in a tracking area containing multiple cells, and handle the signaling connection between the terminal device and the core network. The gateway node can handle data routing in the core network, as well as data routing to / from the terminal device. The 5G specification specifies the core network as a 5G core network (5GC), and the core network may include an advanced mobile management entity (AMF) and a gateway node. The AMF can handle the mobility of the terminal device in the tracking area containing multiple cells, and handle the signaling connection between the terminal device and the core network. The gateway node can handle data routing in the core network, as well as data routing to / from the terminal device.

[0026] In Rel-16 New Radio (NR / 5G), new quantization schemes have recently been agreed to report linear combination (LC) coefficients (LCC), which form part of the precoding matrix indicator (PMI) reported from the UE to the network in order to support downlink multi-user multiple input multiple output (MU-MIMO). MU-MIMO adds multiple access (multi-user) capabilities to MIMO. In order for a transmitter (e.g., an access node in downlink communications) to perform transmissions to multiple users using multiple antennas while optimizing, for example, throughput, precoding may be required.

[0027] Precoding is a generalization of beamforming to support multi-stream (or multi-layer) transmission in multi-antenna wireless communications. In conventional single-stream beamforming, the same signal is sent from each transmit antenna with appropriate weighting (phase and gain) so that the signal power is maximized at the receiver output. When the receiver has multiple antennas, single-stream beamforming cannot maximize the signal levels on all receive antenna sides at the same time. In order to maximize the throughput in a multi-receive antenna system, multi-stream transmission is usually required. In a point-to-point system, precoding means sending multiple data streams with independent and appropriate weights from the transmit antenna so that the link throughput is maximized at the receiver output. In multi-user MIMO, data streams are intended for different users (e.g., spatial division multiple access, SDMA), and some measures of total throughput can be maximized. Simply put, precoding at the transmitter aims to transform the transmit symbol vector in such a way that the vector arrives at the receiver in the strongest form possible in a given channel.

[0028] The transmitter may need channel information in order to perform appropriate precoding. This may be the purpose of a precoding matrix indicator (PMI). The PMI may be part of the channel state information (CSI) reported by the receiving device to the transmitting device. In practice, the channel state information is limited at the transmitter due to estimation errors and quantization. Feedback of the PMI becomes more complicated as the transmitting device uses different polarizations.

[0029] First, a two-dimensional compression mechanism for PMI reporting in Rel-16 MU-MIMO is outlined, and then a quantization scheme is described in more detail. Although the description is written from a downlink perspective, such that, for example, access node 110 is a transmitter and UE 120, 122 is a receiver, the embodiments may also be applied to uplink communications, or to M2M / D2D communications, and generally to any transmitter-receiver communication link. Similarly, the embodiments may also be applied to single user (SU) MIMO.

[0030] In Rel-16 MU-MIMO PMI feedback, the UE applies compression in the spatial domain (SD) and frequency domain (FD) to a coefficient matrix that represents a set of precoding vectors for a given spatial layer for all configured subbands. Denote W as a subband PMI matrix of size 2N1N2xN3, where N1 and N2 are the number of antenna ports associated with the two polarizations used by the two-dimensional cross-polarization transmit antenna array, and N3 is the number of configured PMI subbands. For simplicity, the PMI matrix may be referred to as a precoder matrix. For a rank indicator (RI) greater than 1, there is one such PMI matrix in each RI spatial layer. For ease of representation in the following, general layer compression is considered because the quantization operation in the Rel-16 MU-MIMO PMI feedback is applied independently to each RI layer. The compression operation on W is linear and can be expressed by the following equation

[0031]

[0032] The column vectors of the matrix W1 are the components of the SD orthogonal basis of size 2L, W f The columns of form an FD orthogonal basis of size M, and is a 2L×M matrix of complex-valued LC coefficients representing a compressed version of the precoder matrix. It may be referred to as a combination matrix or a combination coefficient matrix. That is, the precoder matrix may be compressed, for example, in the spatial domain, such as L<2N1N2, and further compressed in the frequency domain, such as M<N3. Each coefficient in (also called combination coefficient or LC coefficient) can indicate how the channel affects the signal reference within a given spatial beam (component) and on a specific frequency beam (or component). The components of the SD basis and the FD basis are selected from an appropriate (and optionally oversampled) discrete Fourier transform (DFT) codebook. In order to further reduce the signaling overhead, only some of its 2LM LC coefficients are reported, and the remaining coefficients are set to zero. This set of reported LC coefficients is called non-zero (NZ) coefficients. For example, these coefficients are coefficients that exceed a certain predetermined amplitude threshold.

[0033] The PMI report for a given layer (e.g., from a UE to an access node) may include two indicators for SD-based and FD-based subset selection, respectively, a 2L×M bitmap indicating K in the matrix NZ The positions of the non-zero coefficients and the quantized values ​​of these non-zero coefficients.

[0034] Now consider the quantization operation of the non-zero LC coefficients. The amplitude and phase of the coefficients are quantized separately according to the following scheme. Denote the LC coefficients associated with beam l∈{0, 1, ..., 2L-1} and frequency bin m∈{0, 1, ..., M-1} as c l，m , and the strongest coefficient (from K reported using the bitmap NZ non-zero coefficients) is denoted as c l*，m* The UE reports the following in the uplink control information (UCI) for Quantization of non-zero coefficients in:

[0035] 1. For the strongest coefficient index (l*, m*) in the bitmap Bit indicator. This indicates the location (i.e. position) of the strongest coefficient. The strongest coefficient can be determined by the magnitude of the coefficient.

[0036] a. Strongest coefficient C l*，m* .1 (hence, its magnitude / phase is not reported)

[0037] 2. Two polarization specific reference amplitudes:

[0038] a. For the strongest coefficient C l*，m* = 1, since the reference amplitude = 1, it is not reported

[0039] b. For the other polarization, the reference amplitude (i.e. the amplitude of the strongest coefficient associated with the corresponding polarization) is quantized to 4 bits

[0040] The symbol table is (Step size -1.5dB)

[0041] 3. For {c l，m , (l, m) ≠ (l*, m*)}

[0042] a. For each polarization, relative to the relevant polarization-specific reference amplitude p diff (l, m) calculate the differential amplitude p of the coefficient ref (l, m), and quantize it to 3 bits

[0043] The symbol table is (Step size -3dB)

[0044] Note: The final quantization amplitude p l，m Yes ref (l, m)×p diff (l, m)

[0045] b. Quantize each phase to 8PSK (3 bits) or 16PSK (4 bits) (configurable)

[0046] There may be problems with reporting the above parameter 2b (ie the reference amplitude for the weaker polarization(s)) in an Uplink Control Information (UCI) message. The current list of agreed UCI fields is shown in Table 1 below.

[0047]

[0048] Table 1: List of agreed UCI parameters

[0049] Parameter 2b, i.e. the reference amplitude of the weaker polarization, may be included in the last row of the above list of UCI part 2 (amplitude of LC coefficients). Note that the order in which these amplitude values ​​are encoded into the sequence in this UCI field is determined by the bitmap according to a specified reading order, e.g. by increasing dimension indexes, where rows (SD) are the first dimension and columns (FD) are the second dimension. However, this reading order cannot be applied to the reference amplitude of the weaker polarization. This problem may require the definition of new rules to identify the reference amplitude location in the UCI field that quantizes the amplitude of the LC coefficients, or equivalently, the introduction of a separate UCI field for this parameter.

[0050] To understand this problem in more detail, refer to Figure 2A and Figure 2B How the quantization scheme works is described in more detail with examples. Figure 2A It means that before normalization and quantization, it has K NZ = 10 non-zero LC coefficients matrix. Figure 2B The corresponding bitmap is shown. The strongest coefficient for each polarization is highlighted with a dashed cell: c 1，1 For horizontal polarization, C 4，0 For vertical polarization. As mentioned above, with c l*，m* =c 1，1 represents the overall strongest coefficient (ie, over all polarizations).

[0051] As mentioned above, Figure 2A Before quantization An example configuration of non-zero LC coefficients in . The magnitude and phase of the universal coefficients are given by: The strongest coefficient for each polarization is highlighted in the figure and is used as the magnitude reference for the magnitude quantization of its polarization. In this example, the overall strongest coefficient is found in the horizontal polarization and is represented by c l*，m* , while the strongest coefficient for the other polarization (weaker) is C 4，0 .

[0052] Before applying the scalar quantizer to the amplitude and phase, they are normalized as follows.

[0053] Phase normalization: by the strongest phase c l*，m*Normalize the phase of all coefficients: φ l，m →φ l，m -φ l*，m* .

[0054] Amplitude normalization: Normalize the amplitudes of all coefficients in a polarization by their corresponding amplitude reference. For horizontal polarization: a l，m →a l，m / a l*，m* For vertical polarization: a l，m →a l，m / a 4，0

[0055] The reference amplitude for the weaker polarization is denoted by A and is given by: A = a 4，0 / a l*，m* .

[0056] after, Figure 2A The normalized values ​​of the non-zero coefficients in the cell (l, m) become:

[0057] Cell (0, 1):

[0058] Cell (1, 1): This is the reference amplitude for the horizontal polarization, which is assumed to be the stronger polarization in this example, i.e. Provides the strongest polarization in

[0059] ·Cell (2, 3):

[0060] Cell (3, 2):

[0061] Cell (4,0): here, represents the reference amplitude for the vertical polarization, which is assumed to be the weaker polarization in this example,

[0062] Cell (4, 1):

[0063] Cell (5, 1):

[0064] Cell (5, 2):

[0065] Community (6, 6): as well as

[0066] ·Cell (7, 5):

[0067] In addition, scalar quantization can be applied separately to the amplitude and phase of non-zero coefficients. Since the position of the overall strongest coefficient is indicated by the special UCI field "Strongest Coefficient Indicator (SCI)" in Table 1 and has a value of 1, its amplitude and phase are not quantized and not reported. Therefore, there are a total of K in the two fields of UCI part 2 (the last two rows in Table 1). NZ -1 amplitude and K NZ -1 phase to be quantized and reported. For example, these quantized values ​​are reported to the network as a bit sequence.

[0068] The order in which the binary representations of the magnitude and phase of the quantized LC coefficients are arranged in their respective UCI fields can be determined from the bitmap, for example by reading the position of 1 in the "row direction" or "column direction". Other orders are also possible, such as reporting the non-zero coefficients of the horizontal polarization first, then the non-zero coefficients of the vertical polarization, etc.

[0069] The problem is that the receiver of UCI (or other control signaling) may need to know the reported K NZ - Which of the 1 quantized amplitudes is the quantized normalized reference amplitude A for the weaker polarization vertical q (In this example, vertical polarization.) This is because the network node (or other receiver reporting) may need to multiply the quantized reference amplitude A by the reported quantized amplitude of the weaker polarization. q to reconstruct the amplitude in the weaker polarization. It should be noted that the network node can determine which is the weaker polarization from the SCI parameters and the bitmap. The network node can also determine from the bitmap which quantized amplitudes belong to the weaker polarization. However, no indicator is provided in the bitmap for the location of the strongest coefficient for the weaker polarization, and the network node cannot infer this information from other UCI parameters. In addition, the reference amplitude A is normalized using 4 bits of quantization. q , which has 1 bit more than all other amplitudes, so that network nodes do not know the normalized reference amplitude A q In the case of the position, it is impossible to parse the binary sequence of the amplitudes of the LC coefficients in the UCI field.

[0070] To at least partially address this problem, one possible solution could be to add an indicator for the location of the strongest coefficient for the weaker polarization in the UCI. NZ are known, the indicator may need or Where K0 is a parameter bit configured by the network through higher layer signaling, which sets the maximum number of non-zero coefficients for any layer. However, this may require considerable signaling overhead.

[0071] Therefore, it may be more beneficial to solve this problem with another solution such that an indication of the position / location of the strongest coefficient for the weaker polarization in the bitmap is provided with less signaling overhead. As will be shown, this solution may further avoid the need to explicitly indicate the coefficient position.

[0072] Figure 3 The solution is described from the perspective of a first device (eg, a receiving device such as UE 120 or 122).

[0073] In step 300, the UE may receive transmissions / communications on two different polarizations from a second device (e.g., a network, such as from access node 110) over a wireless channel. The transmission may include data or control signaling. The transmission may include a reference signal. The reference signal may be, for example, a cell-specific reference signal. In one embodiment, the network may send a channel state information reference signal (CSI-RS) to allow CSI / PMI estimation and calculation at the UE. The polarizations may include, for example, horizontal polarization and vertical polarization.

[0074] In step 302, the UE may determine a plurality of coefficients associated with a precoding matrix (such as W) based on the received channel measurements of step 300, wherein the coefficients at least partially define a combination matrix As explained above, the UE can determine the amplitude (also called magnitude) and phase of the coefficients of the PMI corresponding to specific spatial and frequency domain beams. The determined PMI coefficients can form a matrix that describes how the precoding vector associated with the measured channel changes in the spatial and frequency domains.

[0075] In step 304, the UE may select a coefficient from the coefficients of the weaker polarization, and the selected coefficient is a reference coefficient for the weaker polarization. For simplicity, consider two polarizations, such as Figure 2A The reference coefficient may be a reference coefficient for the selected polarization (ie for the weaker of the two polarizations).

[0076] In an embodiment, the reference coefficient is the coefficient with the largest magnitude among the coefficients of the weaker polarization or the coefficients associated with the weaker polarization. In an embodiment, the strongest polarization is the polarization from which the coefficient with the largest magnitude is measured. In another embodiment, the strongest polarization can be determined based on the average magnitude of all coefficients. Therefore, in an embodiment, the UE can determine the strongest polarization from the two polarizations. Similarly, the UE can determine which is the weakest polarization of the two polarizations. In the above reference Figure 2A In the example, the strongest polarization can be the horizontal polarization because the strongest coefficient c 1，1 is associated with this polarization, and the weaker polarization is the vertical polarization. The reference coefficient is c 4，0, because this is the strongest coefficient for the weaker polarization. As mentioned above, the "strongest coefficient" refers to the coefficient with the largest magnitude.

[0077] In the case where there are two coefficients of equal magnitude, one coefficient associated with each of the two polarizations, there may be a predetermined rule defining which of the two polarizations is considered to be the weaker polarization, and the reference coefficient (e.g., the other of the two equally strong coefficients) is selected from the weaker polarization. If polarization A is associated with two equally strong coefficients x and y, and these two coefficients are the strongest coefficients in polarization A, but the other polarization B is associated with one or more stronger coefficients, then polarization B is the strongest polarization and polarization B is the weaker polarization. In addition, there may be a predefined rule for selecting either coefficient x or y as the reference coefficient for the coefficient for polarization B.

[0078] In step 306, the UE may determine a first indicator and a second indicator for the reference coefficient. In an embodiment, the first indicator indicates a location of the reference coefficient in the combination matrix. In an embodiment, the location of the first indicator in the sequence indicates the location of the reference coefficient c in the combination matrix. 4，0 In an embodiment, the second indicator comprises an amplitude value associated with the reference coefficient.

[0079] In step 308, the UE may report the first indicator and the second indicator to the access node 110. These may be reported in uplink control signaling, such as in a physical uplink control channel (PUCCH) or in a physical uplink shared channel (PUSCH). The report may be part of a PMI report or a CSI report. In an embodiment, the first indicator is included in a sequence sent to the network.

[0080] Figure 4 The proposed solution is shown from the perspective of a second device, such as a network node (eg, access node 110).

[0081] In step 400, an access node may transmit to a first device (e.g., UE 120, 122) via wireless signals on two different polarizations. The transmissions may include data and / or control signaling, as described in conjunction with step 300. The transmissions may include, for example, reference signals that may be used by a receiving device to determine how a channel affects a transmitted signal.

[0082] In step 402, the access node may receive a first indicator and a second indicator from the UE, the first indicator and the second indicator representing reference coefficients for combining coefficients for the weaker polarization, the combining coefficients being associated with the precoding matrix based on channel measurements (performed by the UE), wherein the combining coefficients at least partially define the combining matrix. As explained above, in some embodiments, the reference coefficients are c 4，0, since this is the strongest coefficient for the weaker (vertical) polarization.

[0083] In step 404, the access node 110 may obtain the location of the reference coefficient in the combination matrix based on the first indicator, as will be described below.

[0084] In an embodiment, the UE may also report to the network Figure 2B The bitmap may correspond to a combined matrix. For example, a "1" in the bitmap may represent a non-zero coefficient of the matrix, while a "0" may correspond to a coefficient below a predetermined threshold. In this way, the bitmap may indicate the spatial and frequency domain locations of those coefficients exceeding a predetermined threshold (i.e., non-zero coefficients). The threshold may be an amplitude threshold. In an embodiment, the UE may report the first indicator in a sequence that includes the amplitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient with the largest magnitude. As mentioned above, there are a total of K in the two fields of UCI Part 2 (the last two rows in Table 1). NZ -1 amplitude and K NZ -1 phases are to be quantized and reported. These quantized values ​​may correspond to the magnitude values ​​of the coefficients exceeding a predetermined threshold except for the coefficient with the largest magnitude. However, according to this embodiment, since Using four-bit quantization, the coefficients c are not reported in the sequence. 4，0 In this embodiment, the first indicator represents / indicates / includes a predetermined value in the sequence, such as the bit sequence "111" or "1111", i.e., the maximum quantized value. Other predetermined values ​​known by the UE and the network are also possible. The predetermined value representing "1" can be obtained by dividing the amplitude a by 4，0 Divide by itself.

[0085] It should be noted that the order of the sequence is determined by the bitmap, for example by the positioning of the 1 read in the "row direction" or "column direction". This rule may be known by both communicating components. Therefore, one implementation of the above solution includes using k in the sequence of the UCI field NZ -1 3-bit binary string defines the LCC amplitude, each binary string represents the bitmap except the overall strongest coefficient c 1，1 The number of binary strings and the order of the coefficients in the sequence are the same as in the LCC phase field. However, the differential amplitude of the strongest coefficient corresponding to the weaker polarization is given by a 3-bit binary string representing "1".

[0086] exist Figure 2A In the example and using Figure 2B The row-wise order of the non-zero elements in the bitmap of the UCI LCC amplitude sequence contains the following quantized representations of the normalized differential amplitude values:

[0087]

[0088] The "1" is in the first cell of the sequence because when going through the rows Figure 2A or a non-zero coefficient of 2B, c 4，0 is the first coefficient. Let coefficient C5,1 be the coefficient with the largest magnitude in the weaker polarization, then the position of the first indicator ("1") in the sequence will be the fourth cell (currently read ), the first cell of the sequence is And the current read in the sequence is a 4，0 All denominators will be replaced by a 5，1 .

[0089] In prior art solutions, the first cell in the sequence would include However, the receiver of the sequence knows which bit string in the sequence corresponds to the reference coefficient c of the weaker polarization. 4，0 is not possible. With the current proposal, this is possible because the receiver knows that the UE will use the reference coefficient c at the weaker polarization 4，0 The positioning of is marked with a quantized value of “1” (or some other predetermined value).

[0090] Since we can use the formula Obtained, this predetermined value "1" can be called an amplitude value. In other words, mathematically, such a value is obtained as the differential amplitude of the reference coefficient of the weaker polarization, which implicitly provides the position of such coefficient in the bitmap and, therefore, in the matrix. This is independent of the number of elements of the weaker polarization that have the same amplitude as the reference element. In fact:

[0091] If the weaker polarized reference element is strictly maximal, only one "1" will appear in the entire sequence, ie the 3-bit sequence "111".

[0092] If the reference element of the weaker polarization has the same amplitude (at any rate the largest) as one or more other elements of the weaker polarization, the number of "1" values ​​in the differential amplitude sequence may be as many as the number of elements with the same amplitude. For example, assume that there are 4 coefficients in the weaker polarization, and for simplicity, call them c1, c2, c3, c4. Assume that c1, c3 and c4 have amplitude 3, while c2 has amplitude 2. Now, mark c1 as the reference value. The amplitude of c1 is the largest, although the same as the other 2 coefficients. In this case, there may be a predetermined rule to select one of the 3 coefficients as the reference coefficient. The UE may then calculate c1 / c1=1, c2 / c1=0.66, c3 / c1=1, and c4 / c1=1. The resulting differential amplitude bit sequence may be "111NNN111111", where NNN represents the bit sequence associated with quantization 0.66, and the (multiple) sequence 111 indicates the position of the (multiple) element with the largest amplitude in the weaker polarization.

[0093] In both cases, "1" can still be used as a position indicator for the reference coefficient of the weaker polarization, since it is always the position indicator(s) of the strongest element(s) in the weaker polarization.

[0094] The network node receiving the bitmap and the first indicator in the sequence may derive the reference coefficient c based on the first indicator (eg, its position in the sequence) and the bitmap. 4，0 Positioning in the combination matrix.

[0095] For completeness, note that in an embodiment, the UE reports another sequence for phase in UCI. For example, the LCC phase field of UCI contains the corresponding quantized representation of the following normalized values:

[0096]

[0097] That is, no changes to the reporting of phase may be required.

[0098] In an embodiment, the UE may report a second indicator in a field, the positioning of the second indicator being independent of the first indicator. In an embodiment, the second indicator is reported in a field of the UCI. The field may be a new field relative to the fields listed in Table 1. In another embodiment, the second indicator is reported in a predetermined position in the sequence. In other words, there may be a specific predetermined rule to identify the positioning of the second indicator in the sequence of quantized amplitudes. For example, the rule may be attached at the beginning or end of the sequence. In this way, the position of the second indicator is not determined by the coefficient c 4，0 The positioning in the bitmap is determined not by the position of the image but by different rules.

[0099] In an embodiment, the second indicator represents the reference coefficient c 4，0With respect to the maximum magnitude c 1，1 The magnitude of the coefficient a 1，1 The amplitude of the second device can thus obtain the reference coefficient c 4，0 The amplitude a 4，0 In one embodiment, a 4-bit field may be introduced into UCI Part 2, wherein the 4-bit field includes a quantized representation of the reference amplitude. In the example used, this reference amplitude for the reference coefficient may be represented by the value The quantized bit string is reported as the second indicator.

[0100] In an embodiment, in a 4，0 =a 1，1 In the case of , the value of the quantized value of the second indicator may be "1111" (assuming four-bit quantization is utilized, e.g., the number of bits may vary depending on the specification). Such a "1111" event for the weaker polarization is unlikely, since it would mean that the amplitude of the strongest element of the weaker polarization is the same as the amplitude of the strongest element of the stronger polarization. In general, it is expected that the four-bit sequence associated with the amplitude of the reference value for the weaker polarization is not "1111", but rather represents a value less than 1. Another "NNNN" sequence of values.

[0101] After the network node receives the second indicator, the network node may obtain the reference coefficient c based on the second indicator. 4，0 The magnitude of a 4，0 For example, assuming that the amplitude a 1，1 is 5 and a 4，0 is 3, then the value provided as the second indicator (before quantization) is a 4，0 / a 1，1 =3 / 5=0,6. That is, this is quantized using a certain number of bits (e.g., 4 bits) and sent to the network. The amplitudes of the coefficients of the other weaker polarizations are normalized to a 4，0 , for example, for coefficient c4, the magnitude of 1 is normalized to a in the sequence 4，1 / a 4，0 Assume a 4，1 =2, then the value provided in the sequence represents 2 / 3=0,66 (in quantized value). The network node receiving this can further obtain a 1，1 with a 4，1 , such as 0,6*0,66=0,4. Therefore, the network node may be able to perform reconstruction of the original matrix, up to scaling and phase rotation (assuming that enough quantization bits are used to ignore quantization errors). For example, in this case, the network node 110 may reconstruct: a 1，1 =1,a 4，0 =0.6, a 4，1= 0.4. These values ​​can correspond to 5 (in this hypothetical example, a 1，1 The original value of a) scaled by 1，1 、a 4，0 and a 4，1 The original value of .

[0102] Let us look at the proposed solution in the signaling flow diagram between the device UE 120 and the gNB 110, as shown in Figure 5 As shown. Already combined Figure 3 and Figure 4 Steps 400, 302-308 and 404 are explained. In step 500, the network node 110 may, after receiving the UCI including the PMI report (including the indicator), obtain the location of the reference coefficient for the weaker polarization in addition to the reference coefficient for the stronger polarization, and then adjust the precoding for the UE 120 in an appropriate manner. Thereafter, the network node 110 and the UE 120 may communicate in an efficient manner according to the adjusted precoding. For example, according to some specifications, the gNB may use the PMI communicated by the UE for a given frequency resource to serve the UE on the frequency resource. In addition, there cannot be anything to prevent the gNB from performing appropriate signal processing with the PMIs received from different UEs to ensure that some relationship between them is respected. "Relationship" means that when more than one UE is served (simultaneously) on the same frequency resource, the gNB may want to ensure that the layers sent to more than one UE are in a mutually orthogonal relationship (e.g., forcing zeros). If this is the case, the PMIs sent by more than one UE for the frequency resource may be processed to make them mutually orthogonal.

[0103] This solution may provide an efficient way to include the reference amplitude of the weaker polarization in, for example, a UCI message. This may be important since its position cannot be determined by a bitmap like the other coefficients, and explicitly indicating its position is expensive in terms of overhead. This solution may be applied separately for each RI layer.

[0104] The proposed embodiments may require fewer bits than solutions including explicit indication, where the positioning indicator in the UCI requires (or ) bits. In fact, K NZ and K0 is usually greater than 2 3 = 8. Since the position indicator in the UCI requires more than three bits, and the coefficient c 4，0 The quantized representation of the amplitude requires an additional 4 bits, and a total of at least 8 bits are required to convey the required information to the network device. In the proposed solution, fewer bits are required because a predetermined value in the sequence (such as "1") can be indicated using three bits, and represents the quantized normalized reference amplitude A qThe separation parameters (e.g. in UCI) can be indicated with 4 bits. This requires a total of 7 bits, which is less than at least 8 bits.

[0105] From another point of view, it can be said that the UE receives transmissions on two different polarizations from a second device through a wireless channel; measures multiple coefficients based on the reception; determines a reference coefficient from the coefficient subset for a subset of coefficients; determines a first indicator and a second indicator for the amplitude of the reference coefficient; and reports the first indicator and the second indicator to the second device. As an example of a second device, the network node may then receive a first indicator and a second indicator from the first device, the first indicator and the second indicator representing the amplitude of the reference coefficient for the coefficient subset. As previously described, both the first indicator and the second indicator may be referred to as amplitude indicators. The term "for amplitude" here may refer to an indicator that represents the amplitude / magnitude of the reference coefficient in some way. Examples may include a differential amplitude, which represents the reference coefficient (e.g., c 4，0 ) relative to another amplitude (e.g. relative to a reference coefficient (c 4，0 ) itself or relative to another coefficient (such as c 1，1 or other coefficients). In an embodiment, the reference coefficient is the coefficient with the largest magnitude in the subset of coefficients. In an embodiment, the subset includes coefficients for a specific polarization. In an embodiment, the specific polarization is a weaker polarization.

[0106] like Figure 6 As shown, an embodiment provides an apparatus 10, which includes a control circuit system (CTRL) 12, such as at least one processor, and at least one memory 14 including a computer program code (PROG), wherein the at least one memory and the computer program code (PROG) are configured to, together with the at least one processor, enable the apparatus to perform any of the above processes. The memory can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory.

[0107] In an embodiment, the device 10 may include a terminal device of a communication system, such as a user terminal (UT), a computer (PC), a laptop computer, a tablet computer, a cellular phone, a mobile phone, a communicator, a smart phone, a palm computer, a mobile transportation device (such as a car), a household appliance, or any other communication device collectively referred to as a UE in this specification. Alternatively, the device is included in such a terminal device. In addition, the device may be a module providing a connection (to be attached to the UE) or include a module providing a connection (to be attached to the UE), such as a plug-in unit, a "USB dongle" or any other kind of unit. The unit may be installed inside the UE, or attached to the UE using a connector or even wirelessly.

[0108] In an embodiment, the apparatus 10 is a UE 120 or is included in a UE 120. The apparatus may be caused to perform some of the above-mentioned processes (such as Figure 3 steps) function.

[0109] The device may also include a communication interface (TRX) 16, which includes hardware and / or software for implementing a communication connection according to one or more communication protocols. For example, the TRX may provide the device with communication capabilities to access a radio access network. The device may also include a user interface 18, which includes, for example, at least one keypad, a microphone, a touch display, a speaker, etc. The user interface may be used by a user to control the device.

[0110] According to any embodiment, the control circuit system 12 may include a measurement control circuit system 20 for performing measurements of the received transmission and for determining the coefficients based on the measurements. According to any embodiment, the control circuit system 12 may also include a report control circuit system 22 for processing the measurement results, deriving the first indicator and the second indicator, and controlling the sending of reports to the network. For example, the processing and deriving may include operations such as normalization and quantization.

[0111] like Figure 7 As shown, an embodiment provides an apparatus 50, including a control circuit system (CTRL) 52, such as at least one processor, and at least one memory 54 including a computer program code (PROG), wherein the at least one memory and the computer program code (PROG) are configured to, together with the at least one processor, enable the apparatus to perform any of the above processes. The memory can be implemented using any appropriate data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory.

[0112] In an embodiment, the apparatus 50 may be a network node or included in a network node, such as a gNB / gNB-CU / gNB-DU of 5G. In an embodiment, the apparatus 50 is a network node 110 or included in a network node 110. The apparatus may be enabled to perform some of the above processes (such as Figure 4 steps) function.

[0113] It should be understood that future networks may utilize network function virtualization (NFV), which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that can be operatively connected or linked together to provide services. Virtualized network functions (VNFs) may include one or more virtual machines that use standard or general-purpose servers rather than custom hardware to run computer program codes. Cloud computing or data storage may also be used. In radio communications, this may mean that node operations are implemented at least in part in a central / centralized unit CU (e.g., a server, host, or node) that is operatively coupled to a distributed unit DU (e.g., a radio head / node). It is also possible that node operations will be distributed among multiple servers, nodes, or hosts. It should also be understood that the labor distribution between core network operations and base station operations may vary depending on the implementation.

[0114] In an embodiment, the server may generate a virtual network through which the server communicates with the radio node. In general, a virtual network may involve the process of combining hardware and software network resources and network functions into a single software-based management entity, the virtual network. Such a virtual network may provide a flexible distribution of operations between the server and the radio head / node. In fact, any digital signal processing task may be performed in either the CU or the DU, and the boundary of the transfer of responsibilities between the CU and the DU may be selected depending on the implementation.

[0115] Therefore, in an embodiment, a CU-DU architecture is implemented. In this case, the device 50 may be included in a central unit (e.g., a control unit, an edge cloud server, a server) that is operatively coupled to (e.g., via a wireless or wired network) a distributed unit (e.g., a radio head / node). That is, the central unit (e.g., an edge cloud server) and the radio node may be independent devices that communicate with each other via a radio path or via a wired connection. Alternatively, they may be located in the same entity that communicates via a wired connection, etc. The edge cloud or edge cloud server may serve multiple radio nodes or radio access networks. In an embodiment, at least some of the described processes may be performed by the central unit. In another embodiment, the device 50 may alternatively be included in a distributed unit, and at least some of the described processes may be performed by the distributed unit.

[0116] In an embodiment, the execution of at least some functions of the device 50 can be shared between two physically separate devices (DU and CU) forming an operational entity. Thus, it can be seen that the device depicts an operational entity that includes one or more physically separate devices for performing at least some of the described processes. In an embodiment, this CU-DU architecture can provide a flexible distribution of operations between the CU and the DU. In fact, any digital signal processing task can be performed in the CU or the DU, and the boundary of the transfer of responsibilities between the CU and the DU can be selected according to the implementation. In an embodiment, the device 50 controls the execution of the process regardless of the location of the device and regardless of where the process / function is implemented.

[0117] The device may also include a communication interface (TRX) 56, which includes hardware and / or software for implementing a communication connection according to one or more communication protocols. For example, the TRX may provide the device with communication capabilities to access a radio access network. The device may also include a user interface 58, which includes, for example, at least one keypad, a microphone, a touch display, a speaker, etc. The user interface may be used by a user to control the device.

[0118] The control circuitry 52 may include a transmission control circuitry 60 for controlling transmissions toward and from one or more UEs 120, 122. This may include setting an appropriate precoding vector for obtaining or aiming to optimize MIMO performance according to any embodiment. According to any embodiment, the control circuitry 12 may include a report processing circuitry 62, such as for processing a report received from a UE, the report including a first indicator and a second indicator. For example, the reception of the first indicator and the second indicator from the UE may facilitate setting an appropriate precoding for the UE.

[0119] In an embodiment, an apparatus for implementing at least some of the described embodiments comprises at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to implement the functions described in accordance with any of the embodiments. According to one aspect, when the at least one processor executes the computer program code, the computer program code causes the apparatus to perform the functions described in accordance with any of the embodiments. According to another embodiment, an apparatus for performing at least some of the embodiments comprises at least one processor and at least one memory including computer program code, wherein the at least one processor and the computer program code implement at least some of the functions described in accordance with any of the embodiments. Thus, at least one processor, memory and computer program code form a processing unit for implementing at least some of the described embodiments. According to yet another embodiment, an apparatus for implementing at least some of the embodiments comprises a circuit system, the circuit system comprising at least one processor and at least one memory including computer program code. When activated, the circuit system causes the apparatus to perform at least some of the functions described in accordance with any of the embodiments.

[0120] As used in this application, the term "circuitry" refers to all of the following: (a) hardware-only circuit implementations, such as implementations in analog and / or digital circuits only, and (b) combinations of circuitry and software (and / or firmware), such as, as applicable: (i) a combination of (multiple) processors or (ii) a combination of (multiple) processor portions / software including (multiple) digital signal processors, software, and (multiple) memories that work together to enable the device to perform various functions, and (c) circuitry, such as (multiple) microprocessors or portions of (multiple) microprocessors, that requires software or firmware for operation, even if the software or firmware is not physically present. This definition of "circuitry" applies to all uses of the term in this application. As a further example, as used in this application, the term "circuitry" would also cover an implementation of only a processor (or multiple processors) or portions of a processor and their accompanying software and / or firmware. The term "circuitry" would also cover, for example and if applicable to the particular element, a baseband integrated circuit or application processor integrated circuit for a mobile phone or a similar integrated circuit in a server, cellular network device, or another network device.

[0121] In an embodiment, at least some of the described processes may be implemented by an apparatus including corresponding components for implementing at least some of the described processes. Some example devices for implementing the processes may include at least one of the following: a detector, a processor (including dual-core and multi-core processors), a digital signal processor, a controller, a receiver, a transmitter, an encoder, a decoder, a memory, RAM, ROM, software, firmware, a display, a user interface, a display circuit system, a user interface circuit system, a user interface software, a display software, a circuit, an antenna circuit system, and a circuit system.

[0122] The techniques and methods described herein can be implemented by various means. For example, these techniques can be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. For hardware implementation, the (multiple) devices in the embodiments can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be performed by a module (e.g., a process, a function, etc.) of at least one chipset that performs the functions described herein. The software code can be stored in a storage unit and executed by a processor. The storage unit can be implemented within or outside the processor. In the latter case, as is well known in the art, it can be communicatively coupled to the processor via various means. Additionally, as understood by those skilled in the art, the system components described herein can be rearranged and / or supplemented by additional components to facilitate the implementation of the various aspects described therein, and they are not limited to the precise configuration proposed in a given figure.

[0123] The described embodiments may also be implemented in the form of a computer process defined by a computer program or a portion thereof. Embodiments of the described methods may be implemented by executing at least a portion of a computer program including corresponding instructions. The computer program may be in source code form, object code form, or some intermediate form, and may be stored in some carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer program distribution medium readable by a computer or processor. For example, the computer program medium may be, for example but not limited to, a recording medium, a computer memory, a read-only memory, an electrical carrier signal, a telecommunication signal, and a software distribution packet. The computer program medium may be a non-transient medium. The software coding for implementing the illustrated and described embodiments is fully within the scope of those of ordinary skill in the art.

[0124] The following is a list of some aspects of the invention.

[0125] According to a first aspect, an apparatus is provided, comprising: at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause a first device to: receive transmissions on two different polarizations from a second device via a wireless channel; determine, based on received channel measurements, a plurality of coefficients associated with a precoding matrix, wherein the coefficients at least partially define a combination matrix; select coefficients from the coefficients of a weaker polarization, the selected coefficients being reference coefficients for the weaker polarization; determine a first indicator and a second indicator for the reference coefficients, wherein the first indicator indicates a location of the reference coefficient in the combination matrix, and the second indicator comprises an amplitude value associated with the reference coefficient; and report the first indicator and the second indicator to the second device.

[0126] Various embodiments of the first aspect may include at least one feature from the following bulleted list:

[0127] · reporting to the second device a bitmap corresponding to the combined matrix, the bitmap indicating the spatial and frequency domain locations of those coefficients exceeding a predetermined threshold; reporting to the second device a first indicator in a sequence, the sequence including the magnitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient with the largest magnitude, wherein the order of the sequence is determined by the bitmap, the positioning of the first indicator in the sequence determines the positioning of the reference coefficient in the combined matrix, and wherein the first indicator represents a predetermined value in the sequence.

[0128] - Reporting a second indicator in the field, the second indicator being positioned independently of the first indicator, wherein the second indicator represents the magnitude of the reference coefficient relative to the magnitude of the coefficient having the largest magnitude.

[0129] • wherein the second indicator is reported in a field of uplink control information.

[0130] • wherein the second indicator is reported at a predetermined position in the sequence.

[0131] • where the reference coefficient is the coefficient having the largest magnitude among the coefficients of the weaker polarizations.

[0132] According to a second aspect, an apparatus is provided, comprising: at least one processor and at least one memory comprising computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause a second device to: transmit to a first device on two different polarizations through a wireless channel; receive a first indicator and a second indicator from the first device, the first indicator and the second indicator representing reference coefficients for coefficients of a weaker polarization, the coefficients of the weaker polarization being associated with a precoding matrix based on channel measurements, wherein the coefficients of the weaker polarization at least partially define a combined matrix; and obtain a position of the reference coefficient in the combined matrix based on the first indicator.

[0133] Various embodiments of the second aspect may include at least one feature from the following bulleted list:

[0134] ·Receiving a bitmap corresponding to the combination matrix from the first device, the bitmap indicating the spatial and frequency domain locations of those coefficients exceeding a predetermined threshold; receiving the first indicator from the first device in a sequence, the sequence including the amplitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient with the largest magnitude, wherein the order of the sequence is determined by the bitmap, and wherein the first indicator includes the predetermined value in the sequence; and further deriving the positioning of the reference coefficient in the combination matrix based on the bitmap.

[0135] Receiving a second indicator in the field, the second indicator being positioned independently of the first indicator, wherein the second indicator represents a magnitude of a reference coefficient relative to a magnitude of a coefficient having a maximum magnitude; deriving a magnitude of the reference coefficient based on the second indicator.

[0136] • where the reference coefficient is the coefficient having the largest magnitude among the coefficients of the weaker polarizations.

[0137] According to a third aspect, there is provided a method at a user device, comprising: receiving transmissions on two different polarizations from a network over a wireless channel; determining a plurality of coefficients associated with a precoding matrix based on received channel measurements, wherein the coefficients at least partially define a combination matrix; selecting coefficients among the coefficients of a weaker polarization, the selected coefficients being reference coefficients for the weaker polarization; determining a first indicator and a second indicator for the reference coefficients, wherein the first indicator indicates a location of the reference coefficient in the combination matrix, and the second indicator comprises an amplitude value associated with the reference coefficient; reporting the first indicator and the second indicator to the network. Various embodiments of the third aspect may include at least one feature from the bulleted list of the first aspect.

[0138] According to a fourth aspect, a method at a network node is provided, comprising: transmitting to a user device over a wireless channel on two different polarizations; receiving from the user device a first indicator and a second indicator, the first indicator and the second indicator representing reference coefficients for coefficients of a weaker polarization, the coefficients of the weaker polarization being associated with a precoding matrix based on channel measurements, wherein the coefficients of the weaker polarization at least partially define a combined matrix; deriving a position of the reference coefficients in the combined matrix based on the first indicator. Various embodiments of the fourth aspect may include at least one feature from the bulleted list of the second aspect.

[0139] According to a fifth aspect, there is provided a computer program product, the computer program product being embodied on a computer readable distribution medium and comprising program instructions, wherein when the program instructions are loaded into an apparatus, the program instructions perform the method according to the third aspect. Various embodiments of the fifth aspect may include at least one feature from the bulleted list of the first aspect.

[0140] According to a sixth aspect, there is provided a computer program product, which is embodied on a computer readable distribution medium and comprises program instructions, wherein when the program instructions are loaded into an apparatus, the program instructions perform the method according to the fourth aspect.

[0141] According to a seventh aspect, there is provided a computer program product comprising program instructions, wherein when the program instructions are loaded into an apparatus, the program instructions execute the method according to the third aspect.

[0142] According to an eighth aspect, there is provided a computer program product comprising program instructions which, when loaded into an apparatus, perform the method according to the fourth aspect.

[0143] According to a ninth aspect, a device is provided, comprising an apparatus for executing the method according to the third aspect, and / or a component configured to cause a user device to execute the method according to the third aspect.

[0144] According to a tenth aspect, there is provided an apparatus comprising components for executing the method according to the fourth aspect, and / or a device configured to enable a user device to execute the method according to the fourth aspect.

[0145] According to the eleventh aspect, a computer system is provided, comprising: one or more processors; at least one data storage device; and one or more computer program instructions executed by one or more processors associated with the at least one data storage device for implementing the method according to the third aspect and / or the method according to the fourth aspect.

[0146] Although the present invention has been described above with reference to examples according to the accompanying drawings, it should be clear that the present invention is not limited thereto, but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be understood in a broad sense, and they are intended to illustrate rather than limit the embodiments. It is obvious to those skilled in the art that the concept of the present invention can be implemented in various ways as technology advances. In addition, it is clear to those skilled in the art that the described embodiments can but need not be combined with other embodiments in various ways.

Claims

1. A first device for communication, comprising: at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to: receiving transmissions on two different polarizations from a second device over a wireless channel; determining a plurality of coefficients associated with a precoding matrix based on the received channel measurements, wherein the coefficients at least partially define a combining matrix; selecting coefficients among said coefficients of the weaker said polarization, the selected coefficients being reference coefficients for the weaker said polarization; determining a first indicator and a second indicator for the reference coefficient, wherein the first indicator indicates a location of the reference coefficient in the combination matrix and the second indicator comprises a magnitude value associated with the reference coefficient; reporting to the second device a bitmap corresponding to the combined matrix, the bitmap indicating the spatial and frequency domain locations of those coefficients exceeding a predetermined threshold; Reporting the first indicator and the second indicator to the second device, wherein the first indicator comprises reporting the first indicator to the second device in a sequence, the sequence comprising amplitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient with the maximum magnitude, wherein the first indicator comprises predetermined values ​​in the sequence, and wherein the order of the sequence is determined by the bitmap, and the positioning of the first indicator in the sequence determines the positioning of the reference coefficient in the combination matrix.

2. The first device according to claim 1, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, further cause the first device to: The second indicator is reported in a field, the second indicator being positioned independently of the first indicator, wherein the second indicator indicates the magnitude of the reference coefficient relative to the magnitude of the coefficient having a maximum magnitude. 3 . The first device of claim 1 , wherein the second indicator is reported in a field of uplink control information. The first device of claim 1 , wherein the second indicator is reported at a predetermined position in the sequence.

5. The first device according to claim 1, wherein the reference coefficient is the coefficient having the largest magnitude among the coefficients of the weaker polarization.

6. The first device according to any one of claims 1 to 5, wherein the first device is user equipment.

7. A second device for communication, comprising: at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause a second device to: transmitting to the first device over the wireless channel at two different polarizations; receiving from the first device a bitmap corresponding to a combined matrix, the bitmap indicating spatial and frequency domain locations of those coefficients exceeding a predetermined threshold; receiving, from the first device, a first indicator and a second indicator, the first indicator and the second indicator representing reference coefficients for the coefficients for weaker polarizations, the coefficients being associated with a precoding matrix based on channel measurements, wherein the coefficients at least partially define the combined matrix, wherein receiving the first indicator comprises receiving the first indicator from the first device in a sequence comprising magnitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient having the largest magnitude, wherein an order of the sequence is determined by the bitmap, and wherein the first indicator comprises a predetermined value in the sequence and the second indicator comprises a magnitude value associated with the reference coefficient; The location of the reference coefficient in the combination matrix is ​​obtained based on the first indicator and the bitmap.

8. The second device according to claim 7, wherein at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, further cause the second device to: receiving the second indicator in a field, the second indicator being positioned independently of the first indicator, wherein the second indicator indicates the magnitude of the reference coefficient relative to the magnitude of the coefficient having a largest magnitude; The magnitude of the reference coefficient is derived based on the second indicator.

9. The second device according to claim 7 or 8, wherein the reference coefficient is the coefficient having the largest magnitude among the coefficients of the weaker polarization.

10. A method at a user device, comprising: receiving transmissions on two different polarizations from a network via a wireless channel; determining a plurality of coefficients associated with a precoding matrix based on the received channel measurements, wherein the coefficients at least partially define a combining matrix; selecting coefficients among said coefficients of the weaker said polarization, the selected coefficients being reference coefficients for the weaker said polarization; determining a first indicator and a second indicator for the reference coefficient, wherein the first indicator indicates a location of the reference coefficient in the combination matrix and the second indicator comprises a magnitude value associated with the reference coefficient; reporting to the network a bitmap corresponding to the combined matrix, the bitmap indicating the spatial and frequency domain locations of those coefficients exceeding a predetermined threshold; and reporting the first indicator and the second indicator to the network, wherein reporting the first indicator comprises reporting the first indicator to the network in a sequence comprising magnitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient having the largest magnitude, wherein the first indicator comprises predetermined values ​​in the sequence, and wherein an order of the sequence is determined by the bitmap, and the positioning of the first indicator in the sequence determines the positioning of the reference coefficient in the combination matrix.

11. The method according to claim 10, further comprising: The second indicator is reported in a field, the second indicator being positioned independently of the first indicator, wherein the second indicator indicates the magnitude of the reference coefficient relative to the magnitude of the coefficient having a maximum magnitude.

12. The method of claim 10, wherein the second indicator is reported in a field of uplink control information.

13. The method of any one of claims 10, wherein the second indicator is reported in a predetermined position in the sequence.

14. The method according to any one of claims 10 to 13, wherein the reference coefficient is the coefficient having the largest magnitude among the coefficients of the weaker polarization.

15. A method at a network node, comprising: transmitting to user equipment over a wireless channel on two different polarizations; receiving from the user equipment a bitmap corresponding to a combined matrix, the bitmap indicating spatial and frequency domain locations of those coefficients exceeding a predetermined threshold; receiving, from the user equipment, a first indicator and a second indicator, the first indicator and the second indicator representing reference coefficients for the coefficients for weaker polarization, the coefficients being associated with a precoding matrix based on channel measurements, wherein the coefficients at least partially define the combined matrix, wherein receiving the first indicator comprises receiving the first indicator from the user equipment in a sequence comprising magnitude values ​​of the coefficients exceeding the predetermined threshold except for the coefficient having the largest magnitude, wherein an order of the sequence is determined by the bitmap, and wherein the first indicator comprises a predetermined value in the sequence and the second indicator comprises a magnitude value associated with the reference coefficient; The location of the reference coefficient in the combination matrix is ​​obtained based on the first indicator and the bitmap.

16. The method according to claim 15, further comprising: receiving the second indicator in a field, the second indicator being positioned independently of the first indicator, wherein the second indicator indicates the magnitude of the reference coefficient relative to the magnitude of the coefficient having the largest magnitude, The magnitude of the reference coefficient is derived based on the second indicator.

17. The method according to claim 15 or 16, wherein the reference coefficient is the coefficient having the largest magnitude among the coefficients of the weaker polarization.

18. A computer program product embodied on a computer readable distribution medium and comprising program instructions which, when loaded into a device, execute the method according to any one of claims 10 to 14 or claims 15 to 17.

19. A computer program product comprising program instructions, which, when loaded into a device, execute the method according to any one of claims 10 to 14 or claims 15 to 17.

20. An apparatus for communication comprising means for performing a method according to any one of claims 10 to 14 or claims 15 to 17.

21. A computer system comprising: one or more processors; at least one data storage device, and One or more computer program instructions, which are executed by the one or more processors associated with the at least one data storage device for implementing the method according to any one of claims 10 to 17.

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