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RU-2861372-C1 - ONE-STEP USER EQUIPMENT INITIATED CHANNEL STATE INFORMATION REPORTING

RU2861372C1RU 2861372 C1RU2861372 C1RU 2861372C1RU-2861372-C1

Abstract

FIELD: wireless communication. SUBSTANCE: method comprises steps, at user equipment, of: i) receiving configuration information from a base station of a wireless communication system, the configuration information comprising parameters of predefined time-frequency resources for transmitting a CSI report and a demodulation reference signal (DMRS) port index assigned to the user equipment; ii) processing channel state information reference signals (CSI-RS) received from the base station, and using this processing to check whether at least one predetermined condition is met; and iii) if this at least one condition is met, generating a CSI report and transmitting an uplink (UL) channel to the base station on said predefined time-frequency resources, the UL channel comprising: a DMRS corresponding to the DMRS port assigned to the user equipment, and the CSI report. EFFECT: reducing latency in a user equipment initiated (UEI) channel state information (CSI) reporting procedure and correspondingly reducing power consumption on the user equipment side. 28 cl, 21 dwg

Inventors

  • DAVYDOV ALEXEI VLADIMIROVICH
  • ESIUNIN Denis Viktorovich
  • MOROZOV GREGORY VLADIMIROVICH
  • DIKAREV Dmitry Sergeyevich
  • ERMOLAEV Gregory Aleksandrovich

Dates

Publication Date
20260505
Application Date
20251101

Claims (20)

  1. 1. A method for transmitting channel state information (CSI) in a wireless communication system, comprising the steps of: at a user equipment (UE):
  2. i) receiving configuration information from a base station (BS) of a wireless communication system, wherein the configuration information comprises parameters of predetermined frequency-time resources for transmitting a CSI report and a demodulation reference signal (DMRS) port index specified for the user equipment;
  3. ii) processing channel state information reference signals (CSI-RS) received from the base station and, using this processing, checking whether at least one specified condition is met; and
  4. iii) if at least one of these conditions is met, a CSI report is generated and an uplink (UL) channel is transmitted to the base station on said predetermined frequency-time resources, wherein the UL channel contains: a DMRS corresponding to the DMRS port specified for the user equipment, and a CSI report.
  5. 2. The method of claim 1, wherein the configuration information is transmitted by the base station via one or more downlink (DL) transmissions using radio resource control (RRC) layer signaling.
  6. 3. The method according to paragraph 2, wherein the communication system contains several user equipments, including the said user equipment, which perform steps i)-iii); and each of the user equipments is assigned a different DMRS port.
  7. 4. The method according to claim 3, wherein the configuration information further comprises an indication of said at least one condition.
  8. 5. The method according to paragraph 4, wherein the configuration information further comprises:
  9. the orthogonal code length (OCC), which determines the length L of the orthogonal DMRS sequence, or
  10. the total number of orthogonal DMRS ports, which determines the length L of the orthogonal DMRS sequence.
  11. 6. The method according to claim 5, wherein the length of the OCC or the total number of orthogonal DMRS ports is set by the base station depending on the number of said user equipments.
  12. 7. The method according to claim 5 or 6, wherein the orthogonal DMRS sequences of the corresponding DMRS ports are formed at the user equipments by using Walsh-Hadamard (WH) sequences, wherein the WH OCC of length L is used as a time - domain OCC (TD-OCC) and/or a frequency-domain OCC (FD-OCC) for modulating the corresponding DMRS.
  13. 8. The method according to claim 7, wherein the value of L is one of 2, 4, 8, 12.
  14. 9. The method according to claim 5 or 6, wherein the orthogonal DMRS sequences of the corresponding DMRS ports are generated at the user equipments by using discrete Fourier transform (DFT) sequences, wherein the orthogonal DFT sequence of length L is used as TD-OCC and/or FD-OCC for modulating the corresponding DMRS.
  15. 10. The method according to claim 7, wherein the value of L is one of 2, 3, 4, 6, 8, 12, 14.
  16. 11. The method according to any one of claims 4 to 10, wherein the UL channel is a physical uplink shared channel (PUSCH).
  17. 12. The method according to claim 11, wherein said predetermined frequency- time resources are signaled by the base station to the user equipments using a configured grant, wherein the Configured grant is transmitted as part of the configuration information.
  18. 13. The method according to claim 12, wherein said time- frequency resources are allocated in time on a periodic basis determined by the Configured grant transmission period.
  19. 14. The method according to any one of claims 11 to 13, wherein, in said time-frequency resources, the OFDM symbols on which the DMRS of the respective user equipments are transmitted precede the OFDM symbols on which the CSI reports are transmitted.
  20. 15. The method according to claim 14, wherein the configuration information further comprises an indication of the number of OFDM symbols allocated for transmitting DMRS in PUSCH.

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES The present invention relates generally to wireless communications and, more particularly, to a method for transmitting channel state information (CSI) and related devices. PRIOR ART At the present stage, there is an increasingly active deployment of 5th generation (5G) wireless communication networks of the New Radio (NR) standard, the advantages and capabilities of which are widely known. In the 5G NR system, base stations (BSs) use massive MIMO (mMIMO) antenna arrays containing multiple transmit/receive antenna elements (AEs) to efficiently implement the MIMO (multiple-input multiple-output) technology, where data (e.g., a physical downlink shared channel (PDSCH)) is transmitted to one or more user equipments using multiple spatial MIMO layers. Spatial multiplexing (SM) allows the same frequency and time resources to be used for downlink (DL) transmission of multiple MIMO layers to user equipments, and adaptive beamforming (BF) dynamically controls the transmitted signal in one or more spatial directions; and orthogonal frequency division multiplexing (OFDM) modulation ensures efficient wideband signal transmission in a channel with multipath propagation. The base station antenna array consists of antenna element groups (AE groups). Each AE group can be connected to its own transmit chain, and thus, an AE group constitutes a single physical transmitting element of the base station antenna array. Since the base station antenna array also receives signals, and, accordingly, the aforementioned chain can be implemented as part of the transmit/receive chain, an AE group also constitutes a single receiving element of the antenna array. In 5G NR, base station antenna array AE groups (i.e., physical antennas) are virtualized into logical ports. Depending on the implementation, each AE group can be virtualized into a single logical port, or more than one AE group can correspond to a single logical port. Each logical port has its own associated channel state information reference signal (CSI-RS) port; accordingly, this logical port is called a CSI-RS port of the base station. Generally speaking, CSI-RS are transmitted from the base station to the user equipment(s); the user equipment performs DL channel state measurements based on the received CSI-RS and transmits the channel state information (CSI) to the base station so that the base station can most efficiently transmit the signal downlink to the user equipment. In particular, based on the received CSI, the base station performs digital precoding, i.e., digital beamforming (D-BF) adaptation, to transmit the signal downlink to the user equipment. Next, to provide a more complete understanding of the technical context of the present invention, a general description of the mechanism for obtaining, transmitting and using CSI used in 5G NR is provided. As briefly noted earlier, in 5G NR, CSI-RS are transmitted from the base station to the user equipment so that the user equipment can perform channel estimation for all or a required portion of the CSI-RS ports based on the received CSI-RS. The CSI-RS transmitted by the base station can be subject to corresponding analog beamforming (A-BF) in the analog portion of the base station, defining a specific DL transmission direction or, in other words, an analog beam. In 5G NR, orthogonal multiplexing of the transmitted CSI-RS is applied across frequency domain, time domain, and code domain resources in accordance with the specific CSI-RS configuration used by the base station. 5G NR aspects related to the mapping of CSI-RS ports of the base station to frequency- time resources are disclosed in the TS 38.211 specification, which is incorporated herein by reference in its entirety. When user equipment connects to a cell served by a base station, configuration information is transmitted from the base station to the user equipment. This information generally defines the parameters for signal transmission in the cell. Specifically, CSI-RS resources are configured for the user equipment via radio resource control (RRC) signaling, each corresponding to one of the analog beams used by the base station. Each CSI-RS resource is defined by a set of parameters specified in TS 38.331, v18.1.0, which is incorporated herein by reference in its entirety. According to 5G NR, CSI reports can be transmitted by user equipments in three different modes: periodic, semi-persistent, and aperiodic, which are summarized in Figs. 1a-1c. Figure 1a illustrates the periodic mode, where CSI is transmitted by the user equipment to the base station at a specified period (designated as the 'CSI period' in this figure). In this mode, the CSI message parameters, including the CSI transmission periodicity, are configured by the base station via RRC signaling (at the L3 level). This configuration is designated as the 'RRC configuration' in Figure 1a; the long bar at the bottom of this figure symbolically shows