Method of controlling transmit power with emulation of propagation of reference signal used for loss estimation over channel with precoding, a device implementing the same, and variants thereof

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). The present disclosure relates to a transmit power control method emulating the propagation of reference signal, used for path loss estimation, over channel with precoding, a device implementing the same, and variants thereof. The UE-implemented method comprises the steps of: receiving CSI-RS transmitted from digital ports of a transmit-receive antenna unit of a transmit-receive point for user equipments located in a served cell; measuring a channel from the digital ports of the transmit-receive antenna unit of the transmit-receive point based on said CSI-RS; obtaining a direct indication or approximation of a precoding to be applied by the transmit-receive point for communication with the UE; based on the emulation of propagation of a reference signal from the TRP to the UE over an equivalent channel obtained by applying the obtained precoding or approximation thereof to the measured channel, computing RSRP estimate; determining path loss value based at least in part on the RSRP estimate; and performing uplink transmission to the TRP with transmit power adjusted based at least in part on the determined path loss value. Improved accuracy of reference signal received power estimation, path loss determination, and power control execution, while not increasing overhead, is achieved.

Description

METHOD OF CONTROLLING TRANSMIT POWER WITH EMULATION OF PROPAGATION OF REFERENCE SIGNAL USED FOR LOSS ESTIMATION OVER CHANNEL WITH PRECODING, A DEVICE IMPLEMENTING THE SAME, AND VARIANTS THEREOF

[0001] The present disclosure relates to the field of communications, namely to methods of communication between a user equipment (UE) and a transmission and reception point (TRP), and corresponding devices implementing the corresponding methods. These communication methods use emulation of propagation of a reference signal over a channel with performed precoding, the reference signal is used for loss estimation required for transmit power control.

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th-generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks. Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th-generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0003] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bps and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0004] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz band (for example, 95GHz to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, radio frequency (RF) elements, antennas, novel waveforms having a better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and massive multiple input multiple output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable intelligent surface (RIS).

[0005] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, high-altitude platform stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collison avoidance based on a prediction of spectrum usage; an use of artificial intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as mobile edge computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mecahnisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0007] The sixth generation (6G) mobile communications system, operating in the high and mid-frequency range (9-13 GHz), will support massive antenna systems enabling extreme multiple input multiple output (xMIMO) spatial coding (≥ 1024 antenna elements) with hybrid analog and digital beamforming (BF) at the TRP (e.g. at a base station, BS) with a large number of antenna ports (≥ 128).

[0008] Forming narrow transmit / receive beams with high gains, offered for 6G by xMIMO technology is considered a very attractive approach to compensate for path propagation loss in downlink (DL) and uplink (UL), as well as to enable the use of advanced transmission schemes with multiple MIMO layers.

[0009] For UL transmission, transmit (Tx) power control is employed to ensure comparable receive (Rx) power spectral density (PSD) of UL signals from different UEs, as well as to reduce inter-cell interference and UE power consumption. There are two types of uplink power control: a standalone power control (also referred to as an "open loop" power control), in which the UE itself determines the value of the required transmit power, and a non-standalone power control (also referred to as a "closed loop" power control), in which the UE uses, for the power control, transmit power control commands signaled from the TRP explicitly. Since the UL and DL channels have the property of reciprocity, the UL path loss (PL) is typically measured at the UE through DL measurements.

[0010] To implement power control at the UE, the TRP broadcasts synchronization signal / physical broadcast channel (SS / PBCH) blocks. SS / PBCH blocks are used at the UE for synchronization with the network and based on said blocks the UE measures reference signal received power (RSRP). To transmit SS / PBCH blocks, TRP uses relatively wide transmit beams (see 1 in Fig. 1), so that despite the limitation on the number of transmissions of SS / PBCH blocks in the 3GPP specifications (depending on the frequency used, this number can be 2, 4, 8, 16, 64), SS / PBCH block transmissions cover the entire area served by that TRP. Since subsequently, upon synchronization of UE in the network provided by a specific TRP, that TRP will form and use a (narrower) receive beam from a specific UE, the problem of a mismatch between SS / PBCH transmit beams used at the TRP and data receive beams from specific UEs arises. This mismatch, clearly illustrated in Fig. 1 (compare item 1 in Fig. 1 and the right side of this figure), results in that SS / PBCH-based RSRP measurement carried out at the UE, the subsequent determination of the path loss value based on the measured RSRP and the power control execution based on the determined path loss value are not as accurate as they could be if the reference signal was transmitted from the TRP to a specific UE already with beamforming.

[0011] The mismatch problem described above is solved by generating at the TRP and transmitting, for UE to carry out measurements, a reference signal already beamformed to the specific UE, i.e. the transmission of this reference signal is precoded to the specific UE. CSI-RS for beam management (BM) can be used in this solution as the transmitted reference signal. However, such a solution to the above-described problem of data transmit / receive beams mismatch has the other problem consisting in a significant increase in overhead, because in this case precoded reference signal is generated and transmitted to each UE. In such a solution, the overhead increases as a multiple of the number of active UEs in the cell. This problem is also illustrated in Fig. 1 (see item 2). In addition, this solution may further use, as schematically illustrated in Fig. 1 (see item 2), the reduction in transmit power on the DL to comply with the maximum effective isotropic radiated power (EIRP) requirements, which again makes the matching of data transmit / receive beams worse.

[0012] Therefore, there is a need in the art for an improved solution that allows to estimate the RSRP, determine path loss and perform power control more accurately by taking into account the mismatch of data transmit / receive beams usually existing at the TRP in the above described situations, without increasing overhead.

[0013] Due to the present invention, the above and other problems, although not explicitly stated, but associated with the above-listed problems in the prior art, or arising from them, are solved or at least mitigation of the severity of these problems is achieved. The above and additional problems and the corresponding advantageous technical effects achieved will be discussed further in the following description in the context of the specific features of the technical solution proposed in the present application.

[0014] Provided in a first aspect of the present disclosure is a UE-implemented method of communication with a TRP, the method comprising the steps of: receiving CSI-RS transmitted from digital ports of a transmit-receive antenna unit of the TRP for UEs located in a served cell; measuring a channel from the digital ports of the transmit-receive antenna unit of the TRP based on said CSI-RS; obtaining a direct indication or approximation of a precoding to be applied by the TRP for communication with the UE; based on the emulation of reference signal propagation from the TRP to the UE over an equivalent channel obtained by applying the obtained precoding or approximation thereof to the measured channel, computing RSRP estimate; determining a path loss value based at least in part on the RSRP estimate; and performing uplink transmission to the TRP with transmit power adjusted based at least in part on the determined path loss value.

[0015] The method according to the first aspect allows the UE to emulate, based on the measurement of a cell-specific (i.e., common / same for all UEs) reference signal, propagation of the reference signal over the channel as if the reference signal would be precoded for transmission to said UE (i.e. the reference signal would be UE-specific, i.e. the separate reference signal intended specifically for this UE). The precoding is either obtained in a direct indication from the TRP or by an approximation based on the assumption that, generally, the TRP will perform beamforming to communicate with a given UE in the most optimal manner. Thus, the technical solution claimed in the accompanying claims allows to estimate the RSRP, determine path loss and perform power control more accurately by taking into account data transmit / receive beams mismatch usually existing at the TRP in the above-described situations, without increasing overhead. The above advantageous technical effects are achieved by the combination of features of each independent claim of the accompanying claims. Overhead does not increase, because instead of a precoded reference signal, also referred to herein as the UE-specific reference signal, used is CSI-RS transmitted from the digital ports of the transmit-receive antenna unit of the TRP, which is the cell-specific reference signal, i.e. the reference signal not subjected to precoding. Thus, in the first aspect of the present disclosure, the CSI-RS received at the UE is the unprecoded CSI-RS broadcasted by the TRP.

[0016] In a possible implementation of the first aspect of the present disclosure, the method further comprises a step of receiving the direct indication of said precoding from the TRP, or a step of using, as said precoding, a precoding provided by a precoder determined based on a predefined codebook. The precoder is indicated or determined by a precoding matrix selected from the predefined codebook and signaled by a precoding matrix indicator (PMI) and / or a precoding rank signaled by a rank indicator (RI).

[0017] In a possible implementation of the first aspect of the present disclosure, when the direct indication of said precoding is received from the TRP, PMI and / or RI specifying said precoding is / are received from the TRP in downlink control information (DCI), in medium access control (MAC) signaling or in radio resource control (RRC) signaling.

[0018] In a possible implementation of the first aspect of the present disclosure, depending on RRC configuration and / or capabilities of the UE, Type 1 codebook or enhanced Type 2 codebook is used as the predefined codebook.

[0019] In a possible implementation of the first aspect of the present disclosure, depending on RRC configuration and / or capabilities of the UE, Rank 1 or Rank 2 is used as the precoding rank.

[0020] In a possible implementation of the first aspect of the present disclosure, measuring the channel from the digital ports of the transmit-receive antenna unit of the TRP is performed based on a single occasion of CSI-RS.

[0021] In a possible implementation of the first aspect of the present disclosure, configuring the UE to perform one or more or all of the steps of: receiving CSI-RS transmitted from digital ports of the transmit-receive antenna unit of the TRP for UEs being in a served cell; measuring the channel from the digital ports of the transmit-receive antenna unit of the TRP based on said CSI-RS; obtaining the direct indication or approximation of the precoding to be applied by the TRP for communication with the UE; based on the emulation of propagation of the reference signal from the TRP to the UE over an equivalent channel obtained by applying the obtained precoding or approximation of said precoding to the measured channel, estimating RSRP; determining the path loss value based at least in part on the RSRP estimate; and performing uplink transmission to the TRP with transmit power adjusted based at least in part on the determined path loss value, is carried out via RRC signaling. In the other possible implementation of the first aspect of the present disclosure, said steps are configured to be repeated periodically.

[0022] In a possible implementation of the first aspect of the present disclosure, the uplink transmission to the TRP is the transmission of one or more of: physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), sounding reference signal (SRS), physical random access channel (PRACH).

[0023] Provided in a second aspect of the present disclosure is a UE comprising a transmit-receive antenna unit and a processor configured to perform the method according to the first aspect of the present invention or according to any possible implementation of the first aspect of the present invention.

[0024] Provided in a third aspect of the present disclosure is a storage medium storing processor executable instructions, which, when executed by the processor of a device equipped with a transmit-receive antenna unit, ensure the performance of the method according to the first aspect of the present invention or according to any possible implementation of the first aspect of the present invention.

[0025] Provided in a fourth aspect of the present disclosure is a TRP-implemented method of communication with UE, the method includes the steps of: generating CSI-RS to be transmitted from digital ports of a transmit-receive antenna unit of the TRP for UEs located in a served cell; broadcasting the generated CSI-RS without precoding; and receiving an uplink transmission from the UE with transmit power adjusted based at least in part on a path loss value determined based at least in part on RSRP estimate computed based on the emulation of reference signal propagation over an equivalent channel obtained by applying, to a measured channel, actually used or approximated precoding used by the TRP to communicate with said UE, wherein the measured channel is obtained from a measurement of CSI-RS single occasion in the channel used between the TRP and the UE. In a possible implementation of the fourth aspect of the present disclosure, the CSI-RS is CSI-RS broadcasted periodically, semi-periodically or aperiodically.

[0026] In a possible implementation of the fourth aspect of the present disclosure, the method further comprises a step of transmitting a direct indication of said precoding to the UE. The precoder is indicated by a precoding matrix selected from a predefined codebook and signaled by a precoding matrix indicator (PMI) and / or a precoding rank signaled by a rank indicator (RI).

[0027] In a possible implementation of the fourth aspect of the present disclosure, the indication of said precoding includes the PMI and / or the RI of the precoding. When the direct indication of said precoding is transmitted to the UE, PMI and RI defining a corresponding precoder providing such a precoding are transmitted to the UE in DCI, in MAC signaling or in RRC signaling.

[0028] In a possible implementation of the fourth aspect of the present disclosure, the precoding matrix is selected from the predefined codebook that, depending on RRC configuration and / or UE capabilities, is Type 1 codebook or enhanced Type 2 codebook.

[0029] In a possible implementation of the fourth aspect of the present disclosure, depending on RRC configuration and / or UE capabilities, Rank 1 or Rank 2 is used as the precoding rank.

[0030] In a possible implementation of the fourth aspect of the present disclosure, the method further comprises: the step of configuring by the TRP, using RRC signaling, the UE to perform one or more or all of the following steps: receiving CSI-RS transmitted from digital ports of the transmit-receive antenna unit of the TRP for UEs being in a served cell; measuring the channel from the digital ports of the transmit-receive antenna unit of the TRP based on said CSI-RS; obtaining the direct indication or approximation of the precoding to be applied by the TRP for communication with the UE; based on the emulation of propagation of the reference signal from the TRP to the UE over an equivalent channel obtained by applying the obtained precoding or approximation of said precoding to the measured channel, estimating RSRP; determining the path loss value based at least in part on the RSRP estimate; and performing uplink transmission to the TRP with transmit power adjusted based at least in part on the determined path loss value.

[0031] In a possible implementation of the fourth aspect of the present disclosure the steps of: generating CSI-RS to be transmitted from digital ports of the transmit-receive antenna unit of the TRP for UEs located in the served cell; broadcasting the generated CSI-RS without precoding; and receiving the uplink transmission from the UE with transmit power adjusted based at least in part on the path loss value determined based at least in part on RSRP estimate computed based on the emulation of reference signal propagation over an equivalent channel obtained by applying, to the measured channel, actually used or approximated precoding used by the TRP to communicate with said UE, wherein the measured channel is obtained from the measurement of CSI-RS single occasion in the channel used between the TRP and the UE, are configured at the TRP to be repeated periodically.

[0032] In a possible implementation of the fourth aspect of the present invention, the received uplink transmission from the UE is a transmission of one or more of: PUSCH, PUCCH, SRS, PRACH.

[0033] Provided in a fifth aspect of the present disclosure is a transmission and reception point comprising a transmit-receive antenna unit and a processor configured to perform the method according to the fourth aspect of the present invention or according to any possible implementation of the fourth aspect of the present invention.

[0034] Provided in a sixth aspect of the present disclosure is a storage medium storing processor executable instructions, which, when executed by the processor of a device equipped with a transmit-receive antenna unit, ensure the performance of the method according to the fourth aspect of the present invention or according to any possible implementation of the fourth aspect of the present invention.

[0035] In a seventh aspect of the present invention, there is provided a communication system comprising one or more transmission and reception points according to the fifth aspect of the present invention or according to any possible implementation of the fifth aspect of the present invention, and one or more user terminals according to the second aspect of the present invention or according to any possible implementation of the second aspect of the present invention.

[0036] Therefore, the technical solutions described herein make it possible to estimate RSRP, determine path loss and perform power control more accurately by taking into account the mismatch of data transmit / receive beams, which typically exists in prior art at TRP, without increasing overhead. Such an estimation, according to the present disclosure, can be carried out from a single occasion of CSI-RS, which increases the accuracy and representativeness of channel measurement based on such a signal and, at least in certain cases, may contribute to simplification of the hardware and software implementation of the UE, because there is no need to measure the channel from several reference signals with subsequent averaging of such measurements.

[0037] Fig. 1 schematically illustrates problems encountered in prior art.

[0038] Fig. 2 is a schematic representation of flows of operations performed by the UE (right side of the figure) and performed by the TRP (left side of the figure) to perform communication between them according to an embodiment based on the first and fourth aspects of the present invention, respectively.

[0039] Fig. 3 is a schematic representation of an array of two-dimensional (2D) discrete Fourier transform (DFT)-based beamforming vectors in a precoding matrix structure of a codebook, which, in accordance with embodiments of the present invention, is reported in the direct indication from the TRP or approximated at the UE.

[0040] Fig. 4 is a schematic representation of a transmit-receive beam used at the TRP, when the beamforming to a specific UE is performed, and approximated by the UE to be taken into account in computing the RSRP estimate and determining the path loss according to an embodiment of the present invention.

[0041] Fig. 5 is a schematic comparison of SS / PBCH and CSI-RS in terms of the number of ports used at the TRP for transmitting said reference signals, as well as in terms of time and frequency resources occupied by transmissions of said reference signals.

[0042] Fig. 6 illustrates a schematic representation of the UE according to the second aspect of the present disclosure, which is configured to perform the communication method according to the first aspect of the present disclosure.

[0043] Fig. 7 illustrates a schematic representation of the TRP according to the fifth aspect of the present disclosure, which is configured to perform the communication method according to the fourth aspect of the present disclosure.

[0044] Fig. 8 illustrates a schematic representation of a communication system according to the seventh aspect of the present disclosure.

[0045] Fig. 2 is the schematic representation of flows of operations performed by the UE (right side of the figure) and performed by the TRP (left side of the figure) to implement communication therebetween according to an embodiment based on the first and fourth aspects of the present invention, respectively.

[0046] The communication method performed at the TRP begins and proceeds to the execution of the steps of: generating S200 CSI-RS to be transmitted from digital ports of the transmit-receive antenna unit of the TRP to UEs being in a served cell, and broadcasting S210 the generated CSI-RS from the digital ports of the transmit-receive antenna unit of the TRP. The CSI-RS is a cell-specific CSI-RS that can be broadcasted periodically, semi-periodically or aperiodically. The non-limiting example of such a CSI-RS is the signal used for channel state information feedback (CSI feedback). CSI-RS broadcast is carried out on predetermined time-frequency resources that the UE is aware of in advance or that the UE can derive according to 3GPP specifications. Since the CSI-RS is defined for the entire cell, it is the same for all UEs sensing it in said cell. Therefore, generating and broadcasting this CSI-RS at steps S200 and S210 does not increase overhead, because any precoding of the CSI-RS transmission to a specific UE is not performed.

[0047] In an embodiment, the CSI-RS is generated for transmission from a part of or all digital ports of the transmit-receive antenna unit of the TRP. For xMIMO technology that uses 128 or 256 digital ports, it is preferable for the TRP to transmit CSI-RS from all 128 digital ports or all 256 digital ports at a time. However, CSI-RS broadcasting should not be limited to broadcasting that uses all available digital ports, because in other embodiments it is possible to transmit CSI-RS first from a portion (1 / 2, 1 / 3, 1 / 4, 3 / 4, etc.) of the available digital ports, and then, one or more times, from the remainder of the available digital ports. The structure of the CSI-RS generated at step S200, broadcasted at step S210 and subsequently received / processed at the UE may correspond to, but is not limited to, the CSI-RS structure used in 5G NR, see, e.g., section 8.4.1.5 of the specification TS 38.211 (v.17.5.0).

[0048] The UE-performed method of communication with the TRP begins and proceeds to step S100 of receiving the CSI-RS broadcasted from the digital ports of the transmit-receive antenna unit of the TRP for UEs being in the served cell, and step S110 of measuring the channel based on the received CSI-RS to obtain a channel matrix , where represents the channel measured from all CSI-RS ports on the irxantenna port andk-th subcarrier of CSI-RS. Step S110 can be implemented by any method of channel measurements known in the art. In non-limiting examples, the practical implementation of measuring channel can be performed by comparing the actual received signal passed through the channel being measured with an expected signal (for example, the CSI-RS defined in advance in the 3GPP specification) according to one or more criteria, including, but not limited to, minimum mean square error (MMSE), maximum likelihood (ML), etc.

[0049] Upon measuring the channel the method proceeds to the step of obtaining S120 a direct indication or approximation of the precoding to be applied by the TRP for communication with the UE. In case performed in this step namely is the precoding (i.e., beamforming) approximation, the UE proceeds from the assumption that TRP will perform precoding in the most optimal way. Obtaining precoding at S120 via direct indication or approximation thereof is performed by applying a precoder matrix respectively obtained from the direct indication from the TRP or approximation at the UE to the measured channel . The precoder matrix represents a precoder for the iplayer (for Rank 1 ip= 1, for Rank 2 ip= {1, 2}) specifying the precoding that is most likely (and most rationally) applied on the TRP side for communication with said UE. The selection of the precoder either at the TRP or in the process of said approximation at the UE can be made, in non-limiting embodiments, based on various criteria, including, but not limited to, a network capacity maximization criterion or signal-to-interference-plus-noise ratio (SINR). The non-limiting example of the precoder selection implementation may include a low complexity PMI / RI selection scheme described by D. Ogawa, C. Koike, T. Seyama and T. Dateki in "A Low Complexity PMI / RI Selection Scheme in LTE-A Systems",2013 IEEE 77th Vehicular Technology Conference (VTC Spring), Dresden, Germany, 2013, pp. 1-5, doi: 10.1109 / VTCSpring.2013.6691823, but the precoder selection implementation should not be limited to the mentioned implementation / scheme, because the proposed solution may use other known schemes and / or criteria.

[0050] It should be noted that the precoding direct indication obtained at step S120 may include both explicitly indicated precoding (e.g., in the form of explicitly indicated PMI and / or RI) and implicitly indicated precoding (e.g., codebook type or precoding rank). In the case of the implicit indication, the UE performs the precoding determination (i.e., precoder selection) itself based on the indicated codebook type or rank. For example, the base station reports RI = 1, the UE itself searches (based, e.g., on the above criteria) for a precoder from the rank 1 codebook; in the other example: when the base station reports RI = 2, the UE itself searches for a precoder from a rank 2 codebook. For example, the base station reports that the codebook type is type 1, the UE itself searches for a precoder from the type 1 codebook; in the other example: when the base station reports that the codebook type is type 2 (or enhanced type 2), the UE itself searches for a precoder from the type 2 (or enhanced type 2) codebook. Some of the above non-limiting examples may be combined into one or more other exemplary implementations of the given feature.

[0051] As noted above, the precoder is either a precoder defined (approximated) at the UE according to a predetermined codebook, or a precoder signaled by the TRP in the direct indication (including implicit). In all cases, the precoder is defined by a precoding matrix selected from a predetermined codebook and signaled by PMI, and / or a precoding rank signaled by RI. Because implementation of certain types of codebooks is optional for the UE, the configuration of the codebook for the UE to use shall take into account the UE's capabilities to support a particular codebook. Therefore, depending on whether the RRC configuration and / or UE capabilities support a particular codebook type or a particular precoding rank, a Type 1 codebook or an enhanced Type 2 codebook is used as the predetermined codebook, and Rank 1 or Rank 2 is used as the precoding rank. Said codebook types and precoding ranks are known from prior art, see, e.g., section 5.2.2.2 of the TS 38.214 specification (as to the enhanced Type 2 codebook see namely section 5.2.2.2.5 of said specification). In the case where the direct indication of said precoding is received from the TRP, PMI and / or RI indicating said precoding is received from the TRP in DCI, in MAC signaling, or in RRC signaling.

[0052] Fig. 3 illustrates a schematic representation of the array of 2D DFT-based vectors in the codebook precoding matrix structure, which define the precoding (the beam pattern) reported in the direct indication from the TRP or approximated at the UE. What is shown in this figure should be considered as an example and not as a limitation. The precoding matrix structure shown may be used to represent an optimal (e.g., in terms of minimal losses) beamforming used to emulate the propagation of reference signal from the TRP to the UE over the equivalent channel obtained by applying to the channel actually measured based on the cell-specific CSI-RS, the precoding or an approximation thereof, and computing at step S130 (which will be described in detail below with reference to Fig. 2) RSRP estimate. In the non-limiting example, the selection of a specific precoding matrix (i.e., PMI and RI) can be made from the structure of codebook existing in 5G NR system (see, e.g., section 5.2.2.2 of the TS 38.214 specification), which is applied for adaptive beamforming in downlink.

[0053] Based on the fact that the precoding weight specifying a particular direction is in the form of a DFT-based vector, the possible precoding matrices consist of orthogonal (N1, N2) DFT-based vectors for both directions (vertical, horizontal) and, optionally, corresponding DFT-based vectors obtained by oversampling the orthogonal DFT-based vectors in the spatial domain according to values of O1, O2parameters. The purpose of oversampling, if performed, is to provide a denser array of transmit-receive beams in the spatial domain to fill therein "gaps" between adjacent beams that might exist in certain cases without such oversampling.

[0054] Thus, the structure of precoding matrix based on the predetermined codebook has the DFT structure, namely, the DFT-based array N1O1by N2O2of 2D vectors (a circle in Fig. 3 represents a beam vector, which is two-dimensional because it contains both a transmit / receive beam in the vertical plane and a transmit / receive beam in the horizontal plane), where N1represents the number of digital ports in vertical plane, O1represents the beam sweeping step in vertical plane (elevation angle), N2represents the number of digital ports in horizontal plane, O2represents the beam sweeping step in horizontal plane (azimuth). The general functionality of O1and O2parameters is to define beam sweeping steps for beam management; therefore, the higher the values of O1and O2parameters are, the smaller the step with which the beam can be swept (i.e., for finer angle). In the example illustrated in Fig. 3, N1= 2, N2= 4; O1= 4, O2= 4 (i.e., oversampling by 4 times is performed in both the vertical and horizontal planes); therefore, the resulting dimensionality of the precoding matrix structure in the non-limiting example of Fig. 3 is 8 x 16. Therefore, the grid of beams, which is formed in this example, comprises 128 2D vectors in total. However, the above given values of N1, N2, O1, O2parameters should not be interpreted as limitations, because values of N1, N2, O1, O2parameters may differ from those illustrated in Fig. 3 in an actual implementation; in addition, values of O1and O2parameters are not necessarily equal to each other. It is understood that for xMIMO technology the values of N1, N2, O1, O2parameters will be higher than the values of the corresponding parameters illustrated in Fig. 3, and similar illustrations for xMIMO are not given here to avoid cumbersome figures.

[0055] Each DFT-based 2D vectorvis defined asv= vec(w1 w2), where vec(A) is an operator that transforms a matrix into a column vector by vertically combining / concatenating the columns of the matrix A, w1represents the beam in the vertical plane, w2represents the beam in the horizontal plane, denotes the Kronecker product or equivalent product. Since the antenna array has two polarizations, the DFT-based 2D vectorvfor the other polarization of the antenna array is defined asφv, where the factorφis chosen so as to coherently phase the two polarizations together. The structure described and illustrated with reference to Fig. 3exists in 5G NR systems and is used to adaptively generate beamforming vectors used for downlink transmission.

[0056] Returning to Fig. 2, after performing the step S120 of obtaining the direct indication or approximation of the precoding to be applied by the TRP for communication with the UE, the method proceeds to step S130 of computing RSRP estimate based on the emulation of propagation of a reference signal from the TRP to the UE over an equivalent channel obtained by applying the obtained precoding or approximation thereof to the measured channel. The RSRP estimate is obtained at this step in linear form (for example in milliwatts (mW)) based on the following expression (1) or based on any functionally equivalent modification of this expression (1) or substitution in this expression (1):

[0057] (Expression 1),

[0058] where:

[0059] is layer 1 reference signal received power (L1-RSRP) at the receiving antenna port of the UE, which has the irxindex, wherein total RSRP ≥ ;

[0060] is the number of subcarriers on which unprecoded CSI-RS was broadcasted;

[0061] is the channel measured from all CSI-RS ports on the irxantenna port and thek-th subcarrier of CSI-RS;

[0062] is the precoder (explicitly or implicitly indicated by the TRP, or approximated by the UE) for the iplayer and the CSI-RSk-th subcarrier.

[0063] When ports {1, 2} are used to estimate the RSRP based on the received unprecoded CSI-RS, the RSRP estimate is obtained in linear form (e.g., in mW) based on the modified expression (1.1) or based on any functionally equivalent modification of this expression (1.1) or substitution in this expression (1.1). The modified expression (1.1) differs from the above expression (1) in that linear averaging in it is carried out not only based on the number of subcarriers, but also based on the number of ports for RSRP {1, 2}:

[0064] (Modified Expression 1.1.).

[0065] Performing RSRP estimation as described above with reference to step S130, based on measurement of a single occasion of unprecoded CSI-RS, allows to ensure RSRP accuracy comparable to RSRP accuracy that could be achieved, but at the expense of increased overhead (as described above in the Background section), when RSRP is estimated by measuring precoded CSI-RS. Thus, it should be clear that, in comparison with the prior art, the present invention provides an increased accuracy of RSRP estimation from unprecoded CSI-RS, does not increase overhead and leads only to a slight complication of the hardware and software implementation of the UE.

[0066] Once the RSRP estimate at step S130 is obtained, the method proceeds to the step S140 of determining path loss value based at least in part on the RSRP estimate. The path loss estimate may be obtained at this step, for example, in decibels (dB), based on the following expression (2) known in the art or based on any functionally equivalent modification of this expression (2) or substitution in this expression (2). Measurement units of thereferenceSignalPowerand RSRP components in expression (2) should be brought into consistency with each other before proceeding to path loss determination at this step S140.

[0067] PL=referenceSignalPower- RSRP (Expression 2),

[0068] where:

[0069] referenceSignalPower- the reference signal power that the TRP has previously reported to the UE, or which is predetermined as such in the 3GPP specification, and / or the method in which the UE derives it for various predetermined network conditions / configurations is predetermined as such in the 3GPP specification, and / or depending on other factors; and

[0070] RSRP is the RSRP estimate obtained previously in step S130.

[0071] Determination of the path loss value, which takes into account the RSRP estimate obtained as described above with reference to step S130, based on measurement of the single occasion of unprecoded CSI-RS, allows to ensure RSRP accuracy that is comparable to RSRP accuracy that could be achieved, but at the expense of increased overhead (as described above in the Background section), when in computation of the path loss the RSRP estimate obtained by measuring precoded CSI-RS is taken into account. Therefore, it should be clear that, in comparison with the prior art, the present invention provides an increased accuracy of path loss determination, does not increase overhead and leads only to a slight complication of the hardware and software implementation of the UE.

[0072] Upon determination at step S140 of the path loss the method proceeds to step S150 of performing the uplink transmission to the TRP with transmit power adjusted based at least in part on the determined path loss value. The transmit power adjustment can be made based on the expression (3):

[0073] (Expression 3)

[0074] where:

[0075] is (adjusted) uplink transmit power,

[0076] is the maximum allowed transmit power of the UE, this value may be signaled to the UE in the configuration message from the TRP, alternatively, in some cases, this value may be a maximum output power of the transmitter of the UE,

[0077] is the target reception / transmission power spectral density (PSD) per each 15 kHz physical resource block (PRB), which is preconfigured by the TRP and transmitted in the RRC configuration message, on condition that the path loss is fully compensated,

[0078] μ is numerology adjustment factor, μ = {0, 1, 2, 3, 4} to reflect spacing between individual orthogonal subcarrier frequencies different from the reference spacing of 15 kHz,

[0079] is a number of RBs allocated for PUSCH,

[0080] is path loss compensation control factor α ∈ [0,1], in said range, the extreme value α = 0 means total absence of path loss compensation, and the other extreme value α = 1 means full path loss compensation,

[0081] PL is the path loss estimate between TRP and UE, determined previously in step S140,

[0082] is an optional (i.e. it may not be present) power offset related to a selected modulation and coding scheme (MCS), and

[0083] f is a closed-loop power control component derived from transmit power control commands explicitly signaled from the TRP.

[0084] In the non-limiting exemplary implementation, power adjustment may be carried out in accordance with the technical solution disclosed in the other previously filed application RU 2023119092 (filing date 19.07.2023) of the same applicant (SAMSUNG ELECTRONICS CO., LTD.), entitled as "METHOD OF FREQUENCY-SELECTIVE TRANSMIT POWER CONTROL, DEVICE IMPLEMENTING THE SAME, AND THEIR VARIANTS".

[0085] The uplink transmission in step S150 to the TRP may include, but not limited to, physical uplink shared channel (PUSCH) transmission, physical uplink control channel (PUCCH) transmission, sounding reference signal (SRS) transmission, physical random access channel (PRACH) transmission.

[0086] The power adjustment, carried out before the transmission at step S150, is more accurate because the path loss value used in expression 3 was determined based on the RSRP estimate, for obtainment of which the measurement of unprecoded CSI-RS was performed with the emulation of reception at the UE of the CSI-RS with precoding. This emulation makes it possible to eliminate the transmit / receive beam mismatch described with reference to Fig. 1, as schematically illustrated in Fig. 4. As the consequence of the above, the communication efficiency between the TRP and the UE is improved, the overhead is not increased, and the complication of the UE software and hardware implementation is negligible.

[0087] After the UE performs the transmission in step S150, the TRP in step S230 receives the uplink transmission from the UE. Notably, the communication efficiency between the TRP and the UE is improved since the power of this transmission is adjusted based on the path loss value determined from the RSRP estimate computed based on emulation of the reference signal propagation over the equivalent channel obtained by applying to the measured channel the actually used or approximated precoding used by the given TRP for / when communicating with said UE. The measured channel is obtained from the measurement, in the channel actually used between the given TRP and the UE, of the single occasion of broadcasted CSI-RS that has not been precoded.

[0088] Fig. 2 does not show that the TRP may further transmit downlink control information (DCI) comprising a grant of uplink time-frequency resources (UL grant). By receiving such a grant of time-frequency resources before step S150, the UE will perform the transmission in step S150 in the specified time-frequency resources. In addition, Fig. 2 does not show that the TRP may further request the UE to provide channel state information feedback (CSI feedback); in response to receiving such a request, the UE may compute channel state information (CSI) and feed it back to the TRP. Such CSI information may include one or more of: PMI, Channel Quality Information (CQI), RI, Layer Indicator (LI). These components of the channel state information may be determined by any method known in the art.

[0089] Additionally, Fig. 2 does not show that if the maximum permissible EIRP restriction is used at the TRP for compliance with the requirements or regulations for emitted signal when transmitting the signal with precoding to a particular UE, the amount of this restriction can be taken into account additionally for more accurate approximation (more accurate elimination of beam mismatch described with reference to Fig. 1) of transmit / receive beam that will be used to transmit / receive data after beamforming to the particular UE is performed. To do this,referenceSignalPowerin expression 2 can be adjusted by the appropriate amount.

[0090] Next, with reference to Fig. 5, some features of the unprecoded CSI-RS generated at and broadcasted from the TRP, and subsequently used at the UE to measure the channel, compute the RSRP estimate with emulation of precoding that would be optimal for performing at the TRP to communicate with said UE, determine the path loss with consideration of said RSRP estimate, and adjust UL transmit power based on the determined path loss value are described additionally. As schematically illustrated in Fig. 5, SS / PBCH blocks are transmitted over the channel from a single port of the transmit antenna of the TRP and occupy a narrow frequency band in the channel. Therefore, if SS / PBCH blocks are used for channel measurement, typically it is necessary to measure the channel over several SS / PBCH blocks from different frequency resources of the channel being measured, and then average these measurements to obtain an averaged measurement for the entire channel. It is understood that such an approach may not be sufficiently accurate and representative.

[0091] In the present invention, it is proposed to use unprecoded CSI-RS, which, unlike the SS / PBCH block, is transmitted over the channel from a larger number (in the non-limiting embodiment: from all) transmit antenna ports of the TRP and occupies a large frequency band in the channel (for example, 100% of the total available frequency band; typically CSI-RS occupies the entire band). Authors of the present invention have obtained sufficiently accurate channel estimates even on the basis of a single CSI-RS occasion. In addition, the structure of the CSI-RS itself is more advantageous in terms of how it reflect characteristics of the channel being measured than the structure of the SS / PBCH block, therefore the use of unprecoded CSI-RS instead of SS / PBCH allows to increase the accuracy of the procedures performed at the UE (described above with reference to Fig. 2).

[0092] Fig. 6 illustrates a schematic representation of the UE 400 according to the second aspect of the present invention, which is configured to perform the communication method according to the first aspect of the present invention due to at least that it includes a transmit-receive antenna unit 405 configured to communicate with TRP and any other devices being within the coverage area of the respective cell, and a processor 410 operatively coupled with the transmit-receive antenna unit 405 and configured to perform the method according to the first aspect of the present invention or according to any possible implementation of the first aspect of the present invention. The UE may be, but is not limited to, a mobile phone, a tablet, a laptop, a personal computer, a user wearable electronic device (for example, glasses, watches), AR / VR headset, 'Internet of Things' (IoT) device, in-vehicle equipment or any other mobile communications-enabled electronic devices. The UE may be referred to differently, for example, as a user terminal, a user device, a subscriber device, etc.

[0093] The UE 400 is shown in Fig. 6 in a relatively simplistic, schematic form, therefore shown in this figure are not all components actually comprised in the UE 400, but only those components with which the present invention is carried out. As is known, the UE may comprise another components not shown in the figure, for example, a power supply, a battery, various interfaces, I / O means, interconnections, random access memory and read-only memory storing instructions executable by the processor 410 to carry out the method according to the first aspect of the present invention or according to any possible implementation of the first aspect of the present invention, as well as an operating system, etc. The transmit-receive antenna unit 405 may comprise a transceiver and an antenna coupled to each other. The antenna can be implemented as a massive or extremely massive MIMO antenna array with a large number of antenna ports, which supports hybrid analog and digital beamforming capabilities.

[0094] The processor 410 of the UE 400 may be a central processing unit, a special-purpose processor, another processing unit, for example, a graphics processing unit (GPU), or a combination thereof. The processor 410 may be implemented as a circuit, for example as a Field-Programmable Gate Array (FPGA), an Application-Specific Integrated Circuit (ASIC), a System-on-Chip (SoC), etc.

[0095] Fig. 7 illustrates a schematic representation of the TRP 300 according to the fifth aspect of the present invention, which is configured to perform the communication method according to the fourth aspect of the present invention due to at least that it includes a transmit-receive antenna unit 305 configured to communicate with UE and any other devices being within the coverage area of the respective cell, and a processor 310 operatively coupled with the transmit-receive antenna unit 305 and configured to perform the method according to the fourth aspect of the present invention or according to any possible implementation of the fourth aspect of the present invention. The TRP may be, but not limited to, a Base Station (BS), an Access Point (AP), or Node B.

[0096] The TRP 300 is shown in Fig. 7 in a relatively simplistic, schematic form, therefore shown in this figure are not all components actually comprised in the TRP 300, but only those components with which the present invention is carried out. As is known, the TRP may comprise another components not shown in the figure, for example, a power supply, various interfaces, I / O means, interconnections, random access memory and read-only memory storing instructions executable by the processor 310 to carry out the method according to the fourth aspect of the present invention or according to any possible implementation of the fourth aspect of the present invention, as well as an operating system, etc. The transmit-receive antenna unit 305 may comprise a transceiver and an antenna coupled to each other. The antenna can be implemented as a massive or extremely massive MIMO antenna array with a large number of antenna ports, which supports hybrid analog and digital beamforming capabilities.

[0097] The processor 310 of the TRP 300 may be a central processing unit, a special-purpose processor, another processing unit, for example, a graphics processing unit (GPU), or a combination thereof. The processor 310 may be implemented as a circuit, for example as a Field-Programmable Gate Array (FPGA), an Application-Specific Integrated Circuit (ASIC), a System-on-Chip (SoC), etc.

[0098] Fig. 8 illustrates a schematic representation of a communication system 500 according to the seventh aspect of the present disclosure. The communications system 500 includes one TRP 300, which is installed to serve UEs 400 in three deployed cells 1, 2, 3. The transmission and reception point 300 may correspond to the TRP 300 that is described in detail above with reference to Fig. 7, and each user terminal 400 may correspond to the UE 400 that is described in detail above with reference to Fig. 6, so the detailed description of the TRP 300 and UE 400 is not given here again. The communications system 500 may simultaneously support multiple active radio access technologies (RATs) of, for example, 4G LTE, 5G NR, 6G.

[0099] Specific details shown in Fig. 8 should not be construed as limiting the present technology, because the system 500 may have a different architecture and may be characterized / illustrated differently, for example, each cell of the cell 1, cell 2, cell 3 may correspond to its own TRP 300, a number of UE 400 in the cells may differ from the number shown, the cells 1, 2, 3 may be a single larger cell, a shape and space covered by the cells may differ from the ones shown, etc.

[0100] The present invention may further be implemented as a storage medium storing processor-executable instructions that, when executed by a processor of a device equipped with a transmit-receive antenna unit, perform a method of any aspect of the disclosed invention or any possible implementation of the corresponding aspect. The storage medium may be persistent (non-transitory) computer-readable medium, a memory, a memory area, a storage device, etc., for example, but not limited to, a hard disk, an optical medium, a semiconductor medium, a solid state drive (SSD) or similar.

[0101] Therefore, the technical solutions described herein make it possible to estimate RSRP, determine path loss and perform power control more accurately by taking into account the mismatch of data transmit / receive beams, which typically exists in prior art at TRP, without increasing overhead. Such an estimation, according to the present disclosure, can be carried out from a single occasion of CSI-RS, which increases the accuracy and representativeness of channel measurement based on such a signal and, at least in certain cases, may contribute to simplification of the hardware and software implementation of the UE, because there is no need to measure the channel from several reference signals with subsequent averaging of such measurements.

[0102] Industrial Applicability

[0103] The present invention can be used in 3GPP specification-compliant communication networks with TRP and UE, which support massive MIMO antenna technology with an extremely large number of digital antenna ports (e.g., ≥ 128), analog / digital single-beam / multi-beam beamforming, and TDD and / or FDD duplex modes. Other applications of the technology disclosed herein will become apparent to those ordinary skilled in the art upon reading this detailed description of this application.

[0104] At least one aspect of the disclosed technical solution can be implemented by an artificial intelligence (AI) model. The function associated with the AI can be performed by a non-transitory memory, random access memory, and processor(s) (CPU, GPU, NPU). The processor(s) controls the processing of input data in accordance with a predefined operating rule or an AI model stored in read-only memory and random access memory. The predefined operating rule or AI model is provided through training. Here, "provided through training" means that by applying a learning algorithm to a plurality of training data, the predefined operating rule or AI model with a desired characteristic is created, as an example, but not limited to, the AI model to obtain RSRP estimate (instead of computing it at step S130). Training data in this case may include pairs of measured channel - corresponding RSRP estimate (computed as described above with reference to step S130). The training may be performed in a device itself in which AI according to an embodiment is implemented, and / or may be implemented through a separate server / system. In other examples, the AI model may be created to predict at step S120 precoding to be applied by the TRP for communication with the UE. The training data in this case may include pairs of measured channel - selected precoding.

[0105] The AI model can be a decision tree based algorithm or may consist of a plurality of neural network layers. Each layer has a plurality of weights and performs the operation of the layer through a calculation based on the result of the calculation in the previous layer and the application of a plurality of weights and other parameter values. Examples of decision tree based algorithms include a random forest, tree ensembles, etc., and examples of neural networks include, among others, Convolutional Neural Network (CNN), Deep Neural Network (DNN), Recurrent Neural Network (RNN), Restricted Boltzmann Machine (RBM), Deep Belief Network (DBN), Bi-directional Network, Bi-directional Recurrent Deep Neural Network (BRDNN), Generative Adversarial Network (GAN), Transformer-based Networks, Deep Q-Network, etc.

[0106] A learning algorithm is a method of training a predetermined target device or target function based on a corresponding set of training data that causes, enables, controls, or provides an output of the target device or target function. Examples of learning algorithms include, but not limited to, supervised learning, unsupervised learning, semi-supervised learning or reinforcement learning, and so on.

[0107] A person skilled in the art will appreciate that the various illustrative logical blocks (functional blocks or modules) and steps (operations) used in the embodiments of the disclosed technical solution may be implemented by electronic hardware, computer software, or a combination thereof. Whether the functions are implemented by using hardware or software depends on particular applications and requirements to a design of an entire system. A person skilled in the art may use different methods to implement the described functions for each particular application, but it should not be considered that such an implementation will go beyond the scope of the embodiments disclosed in the application.

[0108] It should also be noted that the order of the steps of any disclosed method is not strict, because one or more steps may be rearranged in the actual order of execution and / or combined with one or more other steps, and / or divided into more sub-steps, for example, step S200 may be combined with step S210, step S110 may be combined with step S120, step S130 may be combined with step S140, etc.

[0109] Throughout this application, reference to an element in the singular form does not preclude the presence of a plurality of such elements in the actual implementation of the invention, and, conversely, reference to an element in the plural form does not exclude the presence of only one such element in the actual implementation of the invention. Any specific value or a range of values stated above should not be interpreted in a limiting sense, but rather such specific value or range of values should be considered to represent the midpoint of the specified larger range, up to approximately 50% on either side of the specified value or specified boundaries of a smaller range.

[0110] While this disclosure has been made and described with reference to specific invention embodiments and examples thereof, those skilled in the art will understand that various changes in form and content may be made without departing from the spirit and scope of this disclosure as defined by the appended claims and their equivalents. In other words, the foregoing detailed description is based on specific examples and possible implementations of the present invention, but should not be interpreted to mean that only the explicitly disclosed implementations are feasible. It is intended that any change or substitution that could be made to this disclosure by one of ordinary skill in the art without creative and / or technical contribution shall be within the scope of protection (with equivalents considered) provided by the following claims.

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:receiving, from a transmission and reception point (TRP), a channel state information reference signal (CSI-RS);performing a channel measurement based on the CSI-RS;receiving, from the TRP, a direct indication or approximation of a precoding to be applied;computing a reference signal received power (RSRP) estimate based on the direct indication or the approximation of the precoding;determining a path loss (PL) value based on the RSRP estimate; andperforming an uplink transmission to the TRP with transmit power adjusted based on the determined path loss value.2.The method of claim 1,wherein the CSI-RS is unprecoded, andwherein the CSI-RS is broadcasted periodically, semi-periodically or aperiodically.3.The method of claim 1,wherein the direct indication is received from the TRP,wherein a precoder is determined based on a predefined codebook, andwherein the precoder is indicated or determined by a precoding matrix selected from the predefined codebook, and the precoder is signaled by a precoding matrix indicator (PMI) or a precoding rank signaled by a rank indicator (RI).4.The method of claim 3,wherein the PMI or the RI is received from the TRP in downlink control information (DCI), in medium access control (MAC) signaling or in radio resource control (RRC) signaling, andwherein Type 1 codebook or enhanced Type 2 codebook is used as the predefined codebook based on RRC configuration or capabilities of the UE, or Rank 1 or Rank 2 is used as the precoding rank base on RRC configuration or capabilities of the UE.5.A method performed by a transmission and reception point (TRP) in a wireless communication system, the method comprising:generating a channel state information reference signal (CSI- RS) to be transmitted to a user equipment (UE);broadcasting the generated CSI-RS without precoding; andreceiving an uplink transmission from the UE with transmit power adjusted based at least in part on a path loss (PL) value determined based on a reference signal received power (RSRP) estimate computed by the UE.6.The method of claim 5,wherein the CSI-RS is broadcasted periodically, semi-periodically or aperiodically.7.The method of claim 5,wherein the direct indication is transmitted to the UE, andwherein the precoder is indicated by a precoding matrix selected from a predefined codebook and signaled by a precoding matrix indicator (PMI) or a precoding rank signaled by a rank indicator (RI).8.The method of claim 7,wherein the direct indication includes the PMI or the RI,wherein the PMI or the RI is transmitted to the UE in downlink control information (DCI), in medium access control (MAC) signaling or in radio resource control (RRC) signaling, andwherein Type 1 codebook or enhanced Type 2 codebook is used as the predefined codebook based on RRC configuration or capabilities of the UE, or Rank 1 or Rank 2 is used as the precoding rank base on RRC configuration or capabilities of the UE.9.A user equipment (UE) in a wireless communication system, the UE comprising:a transceiver; anda controller configured to;receive, from a transmission and reception point (TRP), a channel state information reference signal (CSI-RS),perform a channel measurement based on the CSI-RS,receive, from the TRP, a direct indication or approximation of a precoding to be applied,compute a reference signal received power (RSRP) estimate based on the direct indication or the approximation of the precoding,determine determining a path loss (PL) value based on the RSRP estimate, andperform an uplink transmission to the TRP with transmit power adjusted based on the determined path loss value.10.The UE of claim 9,wherein the CSI-RS is unprecoded, andwherein the CSI-RS is broadcasted periodically, semi-periodically or aperiodically.11.The UE of claim 9,wherein the direct indication is received from the TRP,wherein a precoder is determined based on a predefined codebook, andwherein the precoder is indicated or determined by a precoding matrix selected from the predefined codebook, and the precoder is signaled by a precoding matrix indicator (PMI) or a precoding rank signaled by a rank indicator (RI).12.The UE of claim 11,wherein the PMI or the RI is received from the TRP in downlink control information (DCI), in medium access control (MAC) signaling or in radio resource control (RRC) signaling, andwherein Type 1 codebook or enhanced Type 2 codebook is used as the predefined codebook based on RRC configuration or capabilities of the UE, or Rank 1 or Rank 2 is used as the precoding rank base on RRC configuration or capabilities of the UE.13.A transmission and reception point (TRP) in a wireless communication system, the TRP comprising:a transceiver; anda controller configured to:generate a channel state information reference signal (CSI- RS) to be transmitted to a user equipment (UE),broadcast the generated CSI-RS without precoding, andreceive an uplink transmission from the UE with transmit power adjusted based at least in part on a path loss (PL) value determined based on a reference signal received power (RSRP) estimate computed by the UE.14.The TRP of claim 13,wherein the direct indication is transmitted to the UE, andwherein the precoder is indicated by a precoding matrix selected from a predefined codebook and signaled by a precoding matrix indicator (PMI) or a precoding rank signaled by a rank indicator (RI).15.The TRP of claim 14,wherein the direct indication includes the PMI or the RI,wherein the PMI or the RI is transmitted to the UE in downlink control information (DCI), in medium access control (MAC) signaling or in radio resource control (RRC) signaling, andwherein Type 1 codebook or enhanced Type 2 codebook is used as the predefined codebook based on RRC configuration or capabilities of the UE, or Rank 1 or Rank 2 is used as the precoding rank base on RRC configuration or capabilities of the UE.

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