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EP-4740311-A1 - OVERHEAD REDUCTION FOR CHANNEL STATE INFORMATION REFERENCE SIGNAL WITH LARGE NUMBER OF ANTENNA PORTS

EP4740311A1EP 4740311 A1EP4740311 A1EP 4740311A1EP-4740311-A1

Abstract

This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for overhead reduction for CSI-RS with a large number of antenna ports. A UE receives (308), from a network entity (104), a CSI-RS on a CMR configured based on a resource mapping pattern associated with a number of antenna ports for the CSI-RS being at or above a threshold level. The UE (102) transmits (310), to the network entity (104), a CSI report including measurement information associated with the resource mapping pattern of the CSI-RS.

Inventors

  • LIOU, JIA-HONG
  • ZHANG, YUSHU

Assignees

  • Google LLC

Dates

Publication Date
20260513
Application Date
20230809

Claims (17)

  1. A method of wireless communication at a user equipment, UE, (102) , comprising: receiving (308) , from a network entity (104) , a channel state information-reference signal, CSI-RS, on a channel measurement resource, CMR, configured based on a resource mapping pattern associated with a number of antenna ports for the CSI-RS being at or above a threshold level; and transmitting (310) , to the network entity (104) , a channel state information, CSI, report including measurement information associated with the resource mapping pattern of the CSI-RS.
  2. The method of claim 1, further comprising: receiving (304) , from the network entity (104) , a configuration for at least one of: the CSI report, the CMR associated with the resource mapping pattern, or a subband size for the CSI-RS.
  3. The method of any of claims 1-2, wherein the resource mapping pattern is based on at least one of: a first reduction of CSI-RS resources in frequency-domain, a second reduction of CSI-RS resources in time-domain, or the CSI-RS being associated with a common CSI-RS shared by a plurality of UEs including the UE (102) .
  4. The method of claim 3, wherein the first reduction of the CSI-RS resources in the frequency-domain comprises: receiving (308) , from the network entity (104) , the CSI-RS based on different code division multiplexing, CDM, groups for the CSI-RS located in different resource blocks, RBs.
  5. The method of claim 4, wherein the measurement information comprises: CSI for the subband based on a number of resource elements, REs, for each antenna port for the CSI-RS being greater than or equal to a predetermined number.
  6. The method of claim 3, wherein the second reduction of the CSI-RS resources in the time-domain comprises: receiving (308) , from the network entity (104) , the CSI-RS based on different code division multiplexing, CDM, groups for the CSI-RS located in different slots.
  7. The method of claim 6, wherein the measurement information is based on the CSI-RS located in the different slots.
  8. The method of claim 3, wherein the receiving (308) , from the network entity (104) , the CSI-RS comprises: receiving (308) , on the CMR, the common CSI-RS.
  9. The method of any of claims 1-8, wherein the receiving (308) the CSI-RS on the CMR is based on at least one of: the CMR being associated with the predetermined number of antenna ports, a first number of measured antenna ports in a horizontal direction, a second number of measured antenna ports in a vertical direction, a third number of total antenna ports in the horizontal direction, a fourth number of total antenna ports in the vertical direction, or an antenna ports index.
  10. The method of any of claims 1-9, further comprising: transmitting (302) , to the network entity (104) , a UE capability report indicating at least one of: a supported frequency domain, FD, density for the CSI-RS, a supported frequency domain multiplexing, FDM, scheme for the CDM groups for the CSI-RS, a supported time domain multiplexing, TDM, scheme for the CDM groups for the CSI-RS, a supported frequency domain orthogonal cover code, FD-OCC, length, a supported time domain orthogonal cover code, TD-OCC, length, a minimum number of REs per antenna port per subband for a precoder matrix indicator, PMI, or a minimum number of REs per antenna port per subband for a channel quality indicator, CQI.
  11. The method of any of claims 1-10, wherein the resource mapping pattern indicates at least one of: an RB index and a subcarrier in the RB for each of the CDM groups, a slot index and a starting symbol index within a slot for each of the CDM groups, an antenna port indexing scheme, a CDM length for each of the CDM groups, a CDM type for each of the CDM groups, or a subband size configuration based on the supported FD density of the CMR.
  12. A method of wireless communication at a network entity, (104) , comprising: transmitting (308) , to a user equipment (102) , a channel state information-reference signal, CSI-RS, on a channel measurement resource, CMR, configured based on a resource mapping pattern associated with a number of antenna ports for the CSI-RS being at or above a threshold level; and receiving (310) , from the UE (102) , a channel state information, CSI, report including measurement information associated with the resource mapping pattern of the CSI-RS.
  13. The method of claim 12 wherein the transmitting the CSI-RS comprises: transmitting (308) , to the UE (102) , the CSI-RS based on different code division multiplexing, CDM, groups for the CSI-RS located in different resource blocks, RBs.
  14. The method of any of claims 12-13, wherein the transmitting the CSI-RS comprises: transmitting (308) , to the UE (102) , the CSI-RS based on different code division multiplexing, CDM, groups for the CSI-RS located in different slots.
  15. The method of any of claims 12-14, wherein the transmitting the CSI-RS comprises: transmitting (308) , to a plurality of UEs including the UE, a common CSI-RS shared by the plurality of UEs.
  16. The method of any of claims 12-15, further comprising: transmitting (308) , to another UE (102) , another CSI-RS on another CMR configured based on another resource mapping pattern associated with a number of antenna ports for the another CSI-RS being below the threshold value.
  17. An apparatus for wireless communication comprising a memory, a transceiver, and a processor coupled to the memory and the transceiver, the apparatus being configured to implement a method as in any of claims 1-16.

Description

OVERHEAD REDUCTION FOR CHANNEL STATE INFORMATION REFERENCE SIGNAL WITH LARGE NUMBER OF ANTENNA PORTS TECHNICAL FIELD The present disclosure relates generally to wireless communication, and more particularly, to overhead reduction for channel state information-reference signal (CSI-RS) with large number of antenna ports. BACKGROUND The Third Generation Partnership Project (3GPP) specifies a radio interface referred to as fifth generation (5G) new radio (NR) (5G NR) . An architecture for a 5G NR wireless communication system includes a 5G core (5GC) network, a 5G radio access network (5G-RAN) , a user equipment (5G UE) , etc. The 5G NR architecture seeks to provide increased data rates, decreased latency, and/or increased capacity compared to prior generation cellular communication systems. Wireless communication systems, in general, provide various telecommunication services (e.g., telephony, video, data, messaging, etc. ) based on multiple-access technologies, such as orthogonal frequency division multiple access (OFDMA) technologies, that support communication with multiple UEs. Improvements in mobile broadband continue the progression of such wireless communication technologies. For example, as the number of antenna ports in a wireless system increases, the overhead for channel state information-reference signal (CSI-RS) also increases. This is because each CSI-RS port requires a dedicated resource element (RE) in the frequency domain. BRIEF SUMMARY The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects. This summary neither identifies key or critical elements of all aspects nor delineates the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later. Channel state information-reference signal (CSI-RS) is a signal transmitted by a network entity to enable a user equipment (UE) to estimate the channel between the UE and the network entity based on a measurement of the CSI-RS. The number of CSI-RS ports used to transmit the CSI-RS is associated with the number of independent channel estimates that can be obtained by the UE. For example, a multiple-input multiple-output (MIMO) system with 8 CSI- RS ports can obtain 8 independent channel estimates. As the number of antenna ports in a wireless system increases, the overhead of CSI-RS also increases. This is because each CSI-RS port requires a dedicated resource element (RE) in the frequency domain. For example, a MIMO system with 8 CSI-RS ports requires at least 8 REs per slot. The increasing overhead of CSI-RS can reduce the available bandwidth for data transmission. This is especially true in systems with a limited amount of bandwidth, such as those used for wireless mobile devices. Aspects of the present disclosure address the above-noted and other deficiencies by implementing overhead reduction techniques. In one example, the network entity transmits a configuration to reduce the overhead in frequency-domain, such as by transmitting different code division multiplexing (CDM) groups for a CSI-RS in different resource blocks (RBs) . In another example, the network entity transmits the configuration to reduce the overhead in time-domain, such as by transmitting different CDM groups for a CSI-RS resource in different slots. In a further example, the network entity transmits the configuration to reduce the overhead based on multiple UEs receiving a common CSI-RS. According to some aspects, the UE receives, from the network entity, the CSI-RS on a channel measurement resource (CMR) configured based on a resource mapping pattern associated with a number of antenna ports for the CSI-RS being at or above a threshold level. The UE transmits, to the network entity, a CSI report including measurement information associated with the resource mapping pattern of the CSI-RS. According to some aspects, the network entity transmits, to the UE, the CSI-RS, on a CMR, configured based on a resource mapping pattern associated with a number of antenna ports for the CSI-RS being at or above a threshold level. The network entity receives, from the UE, a CSI report including measurement information associated with the resource mapping pattern of the CSI-RS. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a diagram of a wireless communications system that includes a plurality of user equipments (UEs) and network entities in communication over one or more cells according to an embodiment. FIG. 2 is an example of channel state information-reference signal (CSI-RS) transmission from 32 antenna ports with 4 code division multiplexing (CDM) groups and frequency domain (FD) density as 0.5 according to an embodiment. FIG. 3 is a signaling diagram illustrating communications between a UE and a network entity fo