Overhead reduction of channel state information reference signals under large number of antenna ports

Abstract

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

Description

Technical Field

[0001] This disclosure generally relates to wireless communication, and more specifically to the reduction of overhead for channel state information reference signals (CSI-RS) with a large number of antenna ports. Background Technology

[0002] The 3rd Generation Partnership Project (3GPP) specifies a radio interface called Fifth Generation (5G) New Radio (NR) (5G NR). The architecture of a 5G NR wireless communication system includes a 5G core (5GC) network, a 5G radio access network (5G-RAN), and user equipment (5G UE). Compared to previous generations of cellular communication systems, the 5G NR architecture aims to provide increased data rates, reduced latency, and / or increased capacity.

[0003] Generally, wireless communication systems provide various telecommunications services (e.g., telephony, video, data, messaging) based on multiple access technologies that support communication with multiple users (UEs), such as Orthogonal Frequency Division Multiple Access (OFDMA). Improvements in mobile broadband have continued the development of these wireless communication technologies. For example, as the number of antenna ports in a wireless system increases, the overhead of the 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. Summary of the Invention

[0004] The following is a simplified overview of one or more aspects to provide a basic understanding of such aspects. This overview is not a comprehensive summary of all anticipated aspects. It neither identifies key or important elements of all aspects nor describes 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 an introduction to the more detailed descriptions that follow.

[0005] 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 CSI-RS measurements. The number of CSI-RS ports used to transmit CSI-RS is related to the number of independent channel estimates available to the UE. For example, a Multiple-Input Multiple-Output (MIMO) system with eight CSI-RS ports can obtain eight 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 eight CSI-RS ports requires at least eight REs per time slot. Increased CSI-RS overhead can reduce the available bandwidth for data transmission. This is especially true in systems with limited bandwidth, such as those used for wireless mobile devices.

[0006] The aspects of this disclosure address the aforementioned and other deficiencies by implementing overhead reduction techniques. In one example, a network entity sends a configuration to reduce frequency domain overhead, such as by transmitting different code division multiplexing (CDM) groups of CSI-RS in different resource blocks (RBs). In another example, a network entity sends a configuration to reduce time domain overhead, such as by transmitting different CDM groups of CSI-RS resources in different time slots. In a further example, a network entity sends a configuration to reduce overhead based on multiple UEs receiving a common CSI-RS.

[0007] According to some aspects, the UE receives a CSI-RS from a network entity on a Channel Measurement Resource (CMR) configured based on a resource mapping pattern associated with the number of antenna ports used for the CSI-RS at or above a threshold level. The UE sends a CSI report to the network entity, which includes measurement information associated with the resource mapping pattern of the CSI-RS.

[0008] According to some aspects, the network entity sends a CSI-RS to the UE on a CMR, which is configured based on a resource mapping mode associated with the number of antenna ports used for the CSI-RS at or above a threshold level. The network entity receives a CSI report from the UE, which includes measurement information associated with the resource mapping mode of the CSI-RS. Attached Figure Description

[0009] Figure 1 An illustration of a wireless communication system according to an embodiment is shown, the wireless communication system including a plurality of user equipments (UEs) and network entities communicating through one or more cells.

[0010] Figure 2This is an example of a Channel State Information Reference Signal (CSI-RS) transmission from 32 antenna ports, employing 4 code division multiplexing (CDM) groups and a frequency domain (FD) density of 0.5, according to an embodiment.

[0011] Figure 3 This is a signaling diagram illustrating the communication between a UE and a network entity according to an embodiment for performing Channel State Information (CSI) reporting based on overhead-reduced CSI-RS.

[0012] Figure 4 This is an example of uniformly distributed CSI-RS transmission from 128 antenna ports with an FD density of 0.25, according to an embodiment.

[0013] Figure 5 This is an example of a non-uniformly distributed CSI-RS transmission from 128 antenna ports with an FD density of 0.25, according to an embodiment.

[0014] Figure 6 This is an example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25, using RBs configured with 4 RBs per RB, according to an embodiment.

[0015] Figure 7 This is an example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.5, based on 8 CDM groups in each of 2 configured time slots, according to an embodiment.

[0016] Figure 8 This is an example of a CSI-RS transmission from 128 antenna ports, with an FD density of 0.5, based on configured time slot indices and symbol indices in two time slots, according to an embodiment.

[0017] Figure 9 This is an example of a cyclic mapping with multiple repeating CSI-RS according to an embodiment.

[0018] Figure 10 This is an example of a CSI-RS sequence mapping with multiple repeatings according to an embodiment.

[0019] Figure 11 This is an example of CSI measurement performed by receiving CSI-RS in an available time slot, according to an embodiment.

[0020] Figure 12 This is an example of a shared CSI-RS for UEs with different capabilities according to an embodiment.

[0021] Figure 13 This is an example of a block-based port index compared to a per-CSI-RS resource port index, according to an embodiment.

[0022] Figure 14 This is an example of multiple CSI-RS resources based on CSI measurements according to an embodiment.

[0023] Figure 15 This is an example of multiple CSI-RS resources based on CSI measurements according to another embodiment.

[0024] Figure 16 This is a flowchart of a wireless communication method at the UE according to an embodiment.

[0025] Figure 17 This is a flowchart of a method for wireless communication at a network entity according to an embodiment.

[0026] Figure 18 This is a diagram illustrating a hardware implementation of an example UE device according to some embodiments.

[0027] Figure 19 This is a diagram illustrating a hardware implementation of one or more example network entities according to some embodiments. Detailed Implementation

[0028] Figure 1 A diagram 100 illustrates a wireless communication system associated with multiple cells 190. The wireless communication system includes user equipment (UE) 102 and base station / network entity 104. Some base stations may include an aggregated base station architecture, while others may include a decomposed base station architecture. An aggregated base station architecture utilizes a radio protocol stack physically or logically integrated within a single radio access network (RAN) node. A decomposed base station architecture utilizes a protocol stack physically or logically distributed across two or more units (e.g., radio unit (RU) 106, distributed unit (DU) 108, central unit (CU) 110). For example, CU 110 is implemented within a RAN node, and one or more DU 108s may be located in the same location as CU 110, or alternatively, may be geographically or virtually distributed across one or more other RAN nodes. DU 108 may be implemented to communicate with one or more RU 106s. Any of RU 106, DU 108, and CU 110 can be implemented as a virtual unit, such as a virtual radio unit (VRU), a virtual distributed unit (VDU), or a virtual central unit (VCU). Base station / network entity 104 (e.g., an aggregated base station or a decomposed unit of a base station, such as RU 106 or DU 108) can be referred to as a transmit receiver point (TRP).

[0029] The operation and / or network design of base station 104 can be based on the aggregation characteristics of base station functionality. For example, a decomposed base station architecture can be utilized in an Integrated Access Backhaul (IAB) network, an Open Radio Access Network (O-RAN) network, or a Virtual Radio Access Network (vRAN) (which may also be referred to as a Cloud Radio Access Network (C-RAN)). Decomposition can include distributing functionality among two or more units located in various physical locations, as well as virtually distributing the functionality of at least one unit, which allows for flexibility in network design. Various units in a decomposed base station architecture or a decomposed RAN architecture can be configured to communicate with at least one other unit via wired or wireless communication. For example, base stations 104d, 104e and / or RUs 106a, 106b, 106c, 106d can communicate with UEs 102a, 102b, 102c, 102d and / or 102s via one or more radio frequency (RF) access links based on a Uu interface. In the example, multiple RUs 106 and / or base stations 104 can simultaneously serve UE 102, such as through intra-cell and / or inter-cell access links between UE 102 and RUs 106 / base stations 104.

[0030] RU 106, DU 108, and CU 110 may include (or may be coupled to) one or more interfaces configured to transmit or receive information / signals via wired or wireless transmission media. For example, a wired interface may be configured to transmit or receive information / signals via a wired transmission medium—such as a fronthaul link 160 between RU 106d and a baseband unit (BBU) 112 of base station 104d associated with cell 190d. BBU 112 includes DU 108 and CU 110, and may also have a wired interface (e.g., a midhaul link) configured between DU 108 and CU 110 for transmitting or receiving information / signals between DU 108 and CU 110. In a further example, a wireless interface that may include a receiver, transmitter, or transceiver (such as an RF transceiver) may be configured to transmit and / or receive information / signals via a wireless transmission medium, such as information transmitted between RU 106a in cell 190a and base station 104e in cell 190e via inter-cell communication beams 136-138 of RU 106a and base station 104e.

[0031] RU 106 can be configured to implement lower-level functionality. For example, RU 106 is controlled by DU 108 and can correspond to a logical node that manages RF processing functions or lower-level PHY functions such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, Physical Random Access Channel (PRACH) extraction, and filtering. The functionality of RU 106 can be based on functional partitioning, such as lower-level functional partitioning.

[0032] RU 106 can send or receive over-the-air (OTA) communications with one or more UEs 102. For example, RU 106b of cell 190b communicates with UE 102b of cell 190b via a first communication beamset 132 of RU 106b and a second communication beamset 134b of UE 102b, which may correspond to inter-cell communication beams or, in some examples, inter-cell communication beams. For example, UE 102b of cell 190b can communicate with RU 106a of cell 190a via a third communication beamset 134a of UE 102b and a fourth communication beamset 136 of RU 106a. DU 108 can control the real-time and non-real-time characteristics of control plane and user plane communications of RU 106.

[0033] Any combination or individual reference to RU 106, DU 108, and CU 110 may correspond to base station 104. Therefore, base station 104 may include at least one of RU 106, DU 108, or CU 110. Base station 104 provides UE 102 with access to the core network. Base station 104 may relay communication between UE 102 and the core network (not shown). Base station 104 may be associated with macro cells of high-power cellular base stations and / or small cells of low-power cellular base stations. For example, cell 190e may correspond to a macro cell, while cells 190a-190d may correspond to small cells. Small cells include femtocells, picocells, microcells, etc. A network including at least one macro cell and at least one small cell may be referred to as a "heterogeneous network".

[0034] Transmissions from UE 102 to base station 104 / RU 106 are called uplink (UL) transmissions, while transmissions from base station 104 / RU 106 to UE 102 are called downlink (DL) transmissions. Uplink transmissions can also be called reverse link transmissions, and downlink transmissions can also be called forward link transmissions. For example, RU 106d uses the antenna of base station 104d in cell 190d to transmit downlink / forward link communication to UE 102d via the Uu interface associated with the access link between UE 102d and base station 104d / RU 106d, or receives uplink / reverse link communication from UE 102d.

[0035] The communication link between UE 102 and base station 104 / RU 106 can be based on multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link can be associated with one or more carriers. UE 102 and base station 104 / RU 106 can utilize a per-carrier Y MHz spectral bandwidth (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, 800 MHz, 1600 MHz, 2000 MHz, etc.) allocated in carrier aggregation up to a total of Yx MHz, where x component carriers (CCs) are used for communication in each of the uplink and downlink directions. Carriers can be adjacent to each other along the spectrum or can be non-adjacent. In the example, uplink and downlink carriers can be allocated asymmetrically, with more or fewer carriers allocated for the uplink or downlink. Component carriers can include a primary component carrier and one or more secondary component carriers. The primary component carrier can be associated with the primary cell (PCell), and the secondary component carrier can be associated with the secondary cell (SCell).

[0036] Some UEs 102 (such as UEs 102a and 102s) can perform device-to-device (D2D) communication via a sidelink. For example, the sidelink communication / D2D link utilizes the spectrum of the Wireless Wide Area Network (WWAN) associated with uplink and downlink communication. Such sidelink / D2D communication can be performed by various wireless communication systems, such as Wi-Fi, Bluetooth, LTE, and NR systems.

[0037] UE 102 and base station 104 / RU 106 may each include multiple antennas. These multiple antennas may correspond to antenna elements, antenna panels, and / or antenna arrays that facilitate beamforming operation. For example, RU 106b transmits downlink beamforming signals to UE 102b based on a first communication beamset 132 in one or more transmit directions of RU 106b. UE 102b may receive downlink beamforming signals from RU 106b based on a second communication beamset 134b in one or more receive directions of UE 102b. In a further example, UE 102b may also transmit uplink beamforming signals (e.g., sounding reference signals (SRS)) to RU 106b based on the second communication beamset 134b in one or more transmit directions of UE 102b. RU 106b may receive uplink beamforming signals from UE 102b in one or more receive directions of RU 106b. UE 102b can perform beam training to determine the optimal reception and transmission directions for beamformed signals. The transmission and reception directions of UE 102 and base station 104 / RU 106 may be the same or different.

[0038] In a further example, the beamformed signal can be transmitted between the first base station / RU 106a and the second base station 104e. For example, base station 104e of cell 190e can transmit the beamformed signal to RU 106a based on communication beam 138 in one or more transmit directions of base station 104e. RU 106a can receive the beamformed signal from base station 104e of cell 190e based on RU communication beam 136 in one or more receive directions of RU 106a. In a further example, base station 104e transmits a downlink beamformed signal to UE 102e based on communication beam 138 in one or more transmit directions of base station 104e. UE 102e receives the downlink beamformed signal from base station 104e based on UE communication beam 130 in one or more receive directions of UE 102e. UE 102e can also transmit uplink beamforming signals to base station 104e based on UE communication beam 130 in one or more transmission directions of UE 102e, so that base station 104e can receive uplink beamforming signals from UE 102e in one or more receiving directions of base station 104e.

[0039] Base station 104 may include and / or be referred to as a network entity. That is, a "network entity" may refer to base station 104 or at least one element of base station 104, such as RU 106, DU 108, and / or CU 110. Base station 104 may also include and / or be referred to as Next Generation Evolved Node B (ng-eNB), Next Generation NB (gNB), Evolved NB (eNB), access point, base transceiver, radio base station, radio transceiver, transceiver function, Basic Service Set (BSS), Extended Service Set (ESS), TRP, network node, network device, or other related terms. Base station 104 or the entity at base station 104 may be implemented as an IAB node, relay node, sidelink node, aggregated (monolithic) base station, or a decomposed base station including one or more RU 106, DU 108, and / or CU 110. Aggregated or decomposed base station sets may be referred to as Next Generation Radio Access Network (NG-RAN). In some examples, UE 102a operates in dual connectivity (DC) with base station 104e and base station / RU 106a. In such cases, base station 104e can be the primary node, and base station / RU 106a can be the secondary node.

[0040] Still referencing Figure 1 In some respects, any UE in UE 102 may include a reporting component 140 configured to receive a Channel State Information Reference Signal (CSI-RS) from a network entity on a Channel Measurement Resource (CMR) configured based on a resource mapping pattern associated with the number of antenna ports for the CSI-RS at or above a threshold level; and to send a Channel State Information (CSI) report to the network entity, the report including measurement information associated with the resource mapping pattern of the CSI-RS.

[0041] In some respects, any base station or network entity of base station 104 may include configuration component 150 configured to transmit CSI-RS to UE 102 on CMR, the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; and to receive CSI reports from UE 102, the reports including measurement information associated with the resource mapping mode of the CSI-RS.

[0042] therefore, Figure 1A wireless communication system that can be implemented in conjunction with one or more other figures described herein is described. Furthermore, although the following description may focus on 5G NR, the concepts described herein are applicable to other similar fields, such as 5G-Advanced and future versions, LTE, LTE-advanced (LTE-A), and other wireless technologies such as 6G.

[0043] Figure 2 Illustration 200 shows an example of CSI-RS transmission with 32 antenna ports, employing 4 code division multiplexing (CDM) – 8 groups (frequency domain (FD) 2 + time domain (TD) 4) and an FD density of 0.5. For multiple-input multiple-output (MIMO) systems, CSI can provide information to network entity 104 to select a digital precoder for UE 102. Network entity 104 can use Radio Resource Control (RRC) signaling (e.g., CSI-ReportConfig) to configure CSI reporting, where CSI-RS is used as the CMR for UE 102 to measure downlink channels. Simultaneously, network entity 104 can configure Interference Measurement Resources (IMR) for UE 102 to measure interference.

[0044] Based on the configured CMR and associated IMR, UE 102 can identify the CSI, which may include at least one of the Rank Indicator (RI), Precoder Matrix Indicator (PMI), Channel Quality Indicator (CQI), and Layer Indicator (LI). RI and PMI indicate the digital precoder. CQI indicates the Signal-to-Interference-plus-Noise (SINR) state to assist network entity 104 in determining the modulation and coding scheme (MCS). LI identifies the strongest layer of the reported precoder, as indicated by RI and PMI.

[0045] Currently, network entity 104 can transmit CSI-RS from up to 32 antenna ports. The network entity can transmit CSI-RS using multiple code division multiplexing (CDM) groups. Within each CDM group, the network entity can apply at least one of frequency domain orthogonal coverage code (FD-OCC) or time domain orthogonal coverage code (TD-OCC) for different antenna ports. Different CDM groups can be multiplexed within a resource block (RB) using at least one of frequency domain multiplexing (FDM) or time domain multiplexing (TDM). The network entity can transmit CSI-RS across multiple RBs at the FD density configured for each port ({0.5, 1, 3} resource elements (REs) per RB). Reference Figure 2RB 202 indicates a resource block with CSI-RS, and RB 204 indicates a resource block without CSI-RS. RB 202 includes 168 REs. Example 200 illustrates a structure for 32 CSI-RS port transmission based on a combination of four CDM groups (e.g., CDM group 0 206, CDM group 1 208, CDM group 2 210, and CDM group 3 212) using time-domain and frequency-domain multiplexing in one RB.

[0046] although Figure 2 Four CDM groups are shown (e.g., CDM group 0 206, CDM group 1 208, CDM group 2 210, and CDM group 3 212), but it should be understood that the configuration of the CSI-RS port can be based on combinations of more or fewer than four CDM groups, based on the aspects described in detail below. Therefore, Figure 3 The signaling diagram shows an example scenario in which the UE and network entity exchange messages and implement CSI reporting based on CSI-RS employing overhead reduction techniques.

[0047] Figure 3 Signaling diagram 300 illustrates communication between a UE and a network entity for performing CSI reporting based on CSI-RS employing overhead reduction techniques, according to an embodiment. Network entity 104 may correspond to a base station or an entity at a base station (such as RU 106, DU 108, CU 110, etc.).

[0048] In some examples, initially, UE 102 may send 302 to network entity 104 (and network entity 104 may receive 302 from UE 102) an indication of UE capabilities supporting a resource mapping mode with reduced CSI-RS overhead. UE capabilities may include at least one of the following: supported FD density of the CSI-RS, supported FDM schemes of the CDM group of the CSI-RS, supported TDM schemes of the CDM group of the CSI-RS, supported FD-OCC length, supported TD-OCC length, and minimum number of REs per subband per CSI-RS port for PMI or CQI reporting. UE 102 may report UE capabilities for CSI-RS with a certain number of antenna ports (e.g., 64, 128, or more). Note that embodiments of this disclosure can be applied to CSI-RS with a certain number of antenna ports (e.g., 64, 128, or more).

[0049] Based on UE capabilities, network entity 104 sends 304 to UE 102 (and UE 102 receives 304 from network entity 104) to enable a resource mapping mode with reduced CSI-RS overhead and / or configure the subband size using RRC configuration. Using this RRC configuration, network entity 104 configures the resource mapping mode for CSI-RS resources based on one of the following parameters: RB index and subcarriers in the RB for each CDM group, timeslot index and start symbol index within the timeslot for each CDM group, port indexing scheme, CDM length for each CDM group, and CDM type for each CDM group. Network entity 104 can also configure the subband size based on the FD density of CSI-RS. Network entity 104 can send control signaling via RRC signaling (e.g., RRCReconfiguration or CSI-ReportConfig). Network entity 104 can be configured with a codebook for CSI reporting based on a Type 1 codebook, a Type 2 codebook, an enhanced Type 2 (eType 2) codebook, or a further enhanced Type 2 (feType 2) codebook.

[0050] In some implementations, for semi-persistent CSI reports or aperiodic CSI reports, network entity 104 can send a Media Access Control-Control Element (MACCE) or Downlink Control Information (DCI) to UE 102 (and UE 102 can receive a MACCE from network entity 104) to activate or trigger a CSI report. For semi-persistent CSI-RS or aperiodic CSI-RS, network entity 104 can send a MAC CE or DCI to activate or trigger a CSI-RS.

[0051] Then, network entity 104 sends (and UE 102 receives) CSI-RS resources 308 to UE 102 based on the configured resource mapping pattern. UE 102 measures CSI based on the received CSI-RS resources. UE 102 can further determine the CSI of each subband based on the configured subband size.

[0052] After measuring CSI, UE 102 sends a CSI report to network entity 104 via the Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH) based on CSI-RS and CSI report configuration (and network entity 104 receives it from UE 102).

[0053] In this disclosure, unless otherwise specified, RRC signaling may instruct an RRC reconfiguration message or a System Information Block (SIB) from network entity 104 to UE 102, wherein the SIB may be an existing SIB (e.g., SIB1) or a new SIB sent by the gNB (e.g., SIB J, where J is an integer greater than 21). In some implementations, the network entity may receive UE capabilities from UE 102, from the core network (e.g., Access and Mobility Management Function (AMF)), or from another network entity.

[0054] Figure 3 A signaling diagram is described for an example scenario according to an embodiment, in which the UE and a network entity exchange messages and implement a CSI report based on CSI-RS employing overhead reduction techniques. Figure 4 An example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25, based on a uniform distribution in every 4 RBs, is described according to an embodiment.

[0055] Figure 4 Illustration 400 shows an example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25, based on a uniform distribution in every 4 RBs, according to an embodiment.

[0056] In this embodiment, network entity 104 sends different CDM groups (e.g., CDM groups 0-15) to CSI-RS in different RBs (e.g., 402, 404, 406, 408). Figure 4 As shown, CDM group 0 is 410, CDM group 1 is 412, CDM group 2 is 414, and CDM group 3 is 416. Therefore, CDM group 0 is 410, CDM group 1 is 412, CDM group 2 is 414, and CDM group 3 is 416. CDM groups 4-15 are not included. Figure 4As shown in the diagram, network entity 104 transmits 4 CDMs in each RB. For example, network entity 104 transmits CDM groups 0-3 in RB 402, CDM groups 4-7 in RB 404, CDM groups 8-11 in RB 406, and CDM groups 12-15 in RB 408. In some implementations, network entity 104 can configure the FD density per port, per CDM group, or all CDM groups. In one example, the candidate FD density can be at least one of 0.5, 1 / 3, or 0.25 REs per RB. Therefore, network entity 104 transmits one RE for one port in each N = 2, 3, and / or 4 RBs, respectively. In some other implementations, the FD density can be predefined for a certain number of antenna ports. Therefore, network entity 104 and UE 102 determine the FD density based on the number of antenna ports in the CSI-RS. In one example, the FD density is 0.5 for 64 ports and 0.25 for 128 ports.

[0057] In some implementations, network entity 104 sends CDM groups based on a uniform distribution across every N RBs allocated for CSI-RS. (See reference) Figure 4 Network entity 104 sends CDM groups based on a uniform distribution across every four RBs (e.g., CDM groups 0-3, CDM groups 4-7, CDM groups 8-11, CDM groups 12-15). The network entity can configure a common or separate starting RE index for each CDM group within each RB. In some implementations, the network entity can configure the number of CDM groups per RB. Here, in Figure 4 Each network entity is configured with four CDM groups per RB.

[0058] Figure 4 An example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25, based on a uniform distribution in every 4 RBs, is described according to an embodiment. Figure 5 An example of CSI-RS transmission from 128-port CSI-RS with an FD density of 0.25, based on a non-uniform distribution in every 4 RBs, is shown according to an embodiment.

[0059] Figure 5 Illustration 500 shows an example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25, based on a non-uniform distribution in every 4 RBs, according to an embodiment. In some implementations, network entity 104 transmits CDM groups based on a non-uniform distribution in every N RBs allocated for CSI-RS. For example, refer to... Figure 5510 represents one CDM group. Network entity 104 transmits CSI-RS with 16 CDM groups (e.g., CDM groups 0-15) in two RBs 502 (e.g., 502A, 502B) with CSI-RS. Network entity 104 transmits 12 CDM groups in RB 502A using time-domain and frequency-domain multiplexing. Network entity 104 transmits 4 CDM groups in RB 502B using time-domain and frequency-domain multiplexing. Network entity 104 does not transmit CSI-RS in RB 504. In one example, network entity 104 may transmit CDM groups multiplexed in FDM mode in consecutive subcarriers. The network entity may configure or indicate the starting RE index within consecutive subcarriers. The network entity may configure the starting RB index within every N RBs.

[0060] Figure 5 An example of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25, based on a non-uniform distribution in every 4 RBs, is described according to an embodiment. Figure 6 Example 600 of CSI-RS transmission from 128 antenna ports, with an FD density of 0.25 and using configured RBs of 4 RBs per RB, is shown according to an embodiment.

[0061] In some other implementations, network entity 104 configures RB indices within every N RBs for each CDM group. Network entity 104 further configures starting RE indices within the configured RBs for each CDM group. A first state of bit x can indicate that RB x within every N RBs is not assigned to any CDM group, and a second state of bit x can indicate that RB x within every N RBs is assigned to at least one CDM group. The reverse operation of the first and second states of bit x is also possible.

[0062] refer to Figure 6 For example, network entity 104 configures a bitmap indicating the RB positions of all CDM groups (e.g., 610) within every 4 RBs. For instance, {1 1 1 0} indicates that RB1, 2, and 3 within every 4 RBs are assigned to CDM groups, and RB4 within every 4 RBs is not assigned to a CDM group. RB 602 indicates RBs with CSI-RS, and RB 604 indicates RBs without CSI-RS. Figure 6 As shown, 610 represents one CDM group. Network entity 104 transmits four CDM groups in RB 602A using time-domain and frequency-domain multiplexing. Network entity 104 transmits six CDM groups 610 in RBs 602B and 602C using time-domain and frequency-domain multiplexing.

[0063] Network entity 104 can send CDM groups in a uniform or non-uniform manner across the configured RBs in every N RBs. The number of CDM groups in each configured RB can be determined based on the total number of CDM groups and the number of configured RBs in every N RBs.

[0064] In one example, the number of CDM groups in the first configured RB is And the number of CDM groups in other configured RBs is ,in, Indicates the number of CDM groups and Indicates the number of RBs configured in every N RBs.

[0065] Figure 6 Example 600 of 128-port CSI-RS with an FD density of 0.25 in RBs configured in every 4 RBs according to an embodiment is described, and Figure 7 Example 700 is shown, based on an embodiment, of CSI-RS transmission from 128 antenna ports, with an FD density of 0.5, and based on 8 CDMs in each of 2 configured time slots.

[0066] Figure 7 Illustration 700 shows CSI-RS transmissions from 128 antenna ports, with an FD density of 0.5, based on eight CDM groups in each of two configured time slots, according to an embodiment. Reference Figure 7 RB 702 indicates an RB with CSI-RS, and RB 704 indicates an RB without CSI-RS. In time slot 712A, network entity 104 transmits 8 CDM groups (710A and 710B). In time slot 712B, network entity 104 also transmits 8 CDM groups (710C and 710D).

[0067] In this embodiment, for CSI measurement and CSI reporting, UE 102 measures the CSI of subbands where the number of REs per port is greater than or equal to a threshold. The threshold may be predefined (e.g., 2 REs) or reported by the UE via UE capability.

[0068] In some implementations, network entity 104 avoids configuring CSI-RS and the subband size for subband CSI feedback if the number of REs at the CSI-RS antenna ports in the subband is less than a threshold. Therefore, UE 102 can expect or assume that the number of REs at the CSI-RS antenna ports in the subband used for subband CSI feedback should be greater than or equal to the threshold. In some other implementations, UE 102 can skip or avoid reporting the subband CSI if the number of REs at the CSI-RS antenna ports in the subband is less than the threshold. Alternatively, UE 102 can skip or avoid reporting the entire CSI (i.e., wideband CSI and subband CSI) if the number of REs at the CSI-RS antenna ports in the subband is less than the threshold. Therefore, UE 102 reports the subband CSI of any subband where the number of REs at any CSI-RS antenna port in the subband is greater than or equal to the threshold. In some examples, the threshold may be predetermined or pre-specified in a standard. In some other examples, the threshold may be determined based on UE capabilities.

[0069] In embodiments, network entity 104 transmits different CDM groups of CSI-RS resources in different time slots. In some examples, network entity 104 repeatedly transmits CSI-RS resources in different time slots, where different CDM groups are applied respectively. In some implementations, network entity 104 may configure the number T of time slots for CSI-RS resources or sets of CSI-RS resources. Network entity 104 further configures a start symbol index within each time slot for each CDM group. In some examples, the start symbol index within each time slot of each CDM group is the same, where network entity 104 may configure (only) one start symbol index. In some other examples, the start symbol index within each time slot of each CDM group is different, where network entity 104 may configure multiple start symbol indices for each time slot.

[0070] In some implementations, network entity 104 transmits CSI-RS resources with the same number of CDM groups in each configured T time slot. Network entity 104 and the UE determine the number of CDM groups in each time slot based on the total number of CDM groups and the number of configured time slots. Network entity 104 can configure CSI-RS in T consecutive time slots.

[0071] In one example, the number of CDM groups in the first time slot is The number of CDM groups in other configured time slots is ,in Indicates the number of CDM groups.

[0072] Figure 7Example 700 describes a CSI-RS transmission from 128 ports, with an FD density of 0.5, based on 8 CDM groups in each of 2 configured time slots, according to an embodiment. Figure 8 Example 800 of a CSI-RS transmission from 128 antenna ports, with an FD density of 0.5, based on configured time slot indices and symbol indices in two time slots, is shown according to an embodiment.

[0073] In some other implementations, network entity 104 may transmit CSI-RS with a different number of CDM groups in each of the configured time slots allocated to CSI-RS. (See reference) Figure 8 For example, RB 802 indicates an RB with CSI-RS, and RB 804 indicates an RB without CSI-RS. Network entity 104 can send CSI-RS with 12 CDM groups 810A in time slot 812A and 4 CDM groups 810B in time slot 812B. Network entity 104 can configure the time slot index and symbol index within the configured time slot for each CDM group. In one example, network entity 104 sends CSI-RS instances over or across two time slots and configures the CSI-RS port or CDM group to be in the first or second time slot.

[0074] Figure 8 Example 800 of a 128-port CSI-RS with an FD density of 0.5, based on configured slot indices and symbol indices in two slots, is described according to an embodiment. Figures 9 to 10 Examples 900 and 1000, respectively, of cyclic mapping and sequential mapping with multiple repeating CSI-RS according to embodiments, are shown.

[0075] In some implementations, if network entity 104 is configured to send CSI-RS from multiple duplicates, network entity 104 can perform a round-robin mapping scheme. Network entity 104 can send all CDM groups from one duplicate and then send all CDM groups from another duplicate. For example, see reference... Figure 9 Network entity 104 can send CDM groups 0-7 from one repeat in time slot 902 and CDM groups 8-15 from another repeat in time slot 904.

[0076] In some other implementations, network entity 104 may execute a sequential mapping scheme with multiple duplicate CSI-RS. For example, network entity 104 transmits the CDM group corresponding to the first time slot for all duplicates, and then transmits the CDM group corresponding to the second time slot for all duplicates. (See reference) Figure 10Network entity 104 transmits CDM groups 0-7 corresponding to the first time slot 1002 for all repeated transmissions, and then transmits CDM groups 8-15 corresponding to the second time slot 1004 for all repeated transmissions. Alternatively, the network entity can be configured to transmit multi-slot and multi-repetition CSI-RS using either a sequential mapping scheme or a cyclic mapping scheme.

[0077] In some implementations, network entity 104 configures a common RB for each CDM group in each time slot. In other implementations, network entity 104 can configure different RBs for CDM groups in different time slots. In one example, network entity 104 can configure separate RB locations for each CDM group in each time slot, such as odd-numbered or even-numbered RBs. In another example, network entity 104 can configure whether frequency hopping is enabled. If frequency hopping is enabled, network entity 104 can transmit CDM groups in different time slots based on the configured RBs of the first configured time slot, the time slot index within the configured time slot, and the frequency domain density. Therefore, if network entity 104 transmits CDM groups in odd-numbered RBs in the first configured time slot, then network entity 104 transmits CDM groups in even-numbered RBs in the second configured time slot. Network entity 104 can configure frequency hopping for each CDM group, a subset of CDM groups, or all CDM groups.

[0078] In some implementations, a network entity may transmit a CDM group across two time slots. In other implementations, a network entity may transmit a CDM group within one time slot, and the network entity avoids transmitting a CDM group across two time slots. Therefore, the UE should not expect the network entity to schedule CSI-RS with a CDM group across two time slots. In some other implementations, the UE may report an indication of whether it supports a UE capability with a CDM group across two time slots.

[0079] Figures 9 to 10 Examples 900 and 1000, respectively, of cyclic mapping and sequential mapping with multiple repeating CSI-RS according to embodiments, are described, and Figure 11 An example of CSI measurement by receiving CSI-RS in an available time slot, according to an embodiment, is shown.

[0080] In this embodiment, for CSI measurement and reporting, the UE measures CSI based on the CSI-RS in the configured time slot.

[0081] In some implementations, UE 102 may avoid sending a CSI report if a time slot in the configured time slots of the CSI-RS is dropped, for example, due to a collision with another signal (e.g., an uplink signal). Alternatively, UE 102 may send a CSI report based on outdated CSI (e.g., CSI measured from the last CSI-RS instance or CSI reported in the last CSI report). Alternatively, UE 102 may send a CSI report based on the remaining antenna ports of the CSI-RS. Alternatively, UE 102 may send a CSI report based on both the remaining antenna ports of the CSI-RS and the discarded antenna ports of the most recently transmitted CSI-RS.

[0082] In some other implementations, if one of the configured time slots becomes unavailable for CSI-RS transmission, for example due to a conflict with another signal (e.g., an uplink signal), network entity 104 can transmit CSI-RS in the next available time slot. UE 102 then measures and reports CSI based on the CSI-RS received in the corresponding time slot. (See reference) Figure 11 CSI-RS 1102 conflicts with uplink signal 1104 in time slot 1106. By applying conflict resolution techniques, network entity 104 transmits CSI-RS 1102A in one of the available configured time slots 1108. Alternatively, if a time slot in the configured time slots is unavailable for CSI-RS transmission, for example due to a conflict with another signal (e.g., an uplink signal), network entity 104 may transmit a trigger signal for aperiodic CSI-RS to transmit the discarded portion of the CSI-RS. Network entity 104 may further indicate the association between the triggered CSI-RS and the available portion of the CSI-RS in the trigger signal. UE 102 then measures and reports CSI-RS based on the triggered CSI-RS in the corresponding time slot.

[0083] Figure 11 Example 1100 of CSI measurement according to an embodiment is shown by receiving CSI-RS in an available time slot, and Figure 12 Example 1200 of a shared CSI-RS for UEs with different capabilities according to an embodiment is shown.

[0084] In this embodiment, network entity 104 sends CSI-RS to multiple UEs. Since different UEs may have different capabilities regarding the maximum number of CSI-RS ports they support, network entity 104 can send CSI-RS based on the following port indexing scheme: such that the first K ( Each port corresponds to the first codebook configuration of the first UE (e.g., UE 1), while all CSI-RS ports... Each antenna port corresponds to the second codebook configuration of the second UE (e.g., UE 2).

[0085] In this embodiment, network entity 104 configures the first UE and the second UE with... The UE 102 configures the CSI-RS resources for each antenna port and also configures at least one of the following parameters: the number of measured antenna ports, the number of measured antenna ports in the horizontal and vertical directions, the actual number of antenna ports in the horizontal and vertical directions, or the UE's measured antenna port index. Based on this configuration, the UE 102 determines the antenna ports used for CSI measurement and measures CSI based on the determined antenna ports.

[0086] In one example, such as Figure 12 As shown, network entity 104 can configure the number of measured antenna ports of the first UE (e.g., UE 1) to 16 ports 1204. Network entity 104 further configures the number of measured horizontal antenna ports in the codebook configuration to 4 and the number of measured vertical antenna ports to 2 based on the 16 antenna ports. Network entity 104 configures the number of measured antenna ports of the second UE (e.g., UE 2) to 64 ports 1202. Network entity 104 also configures the number of horizontal antenna ports in the codebook configuration to 8 and the number of vertical antenna ports to 4 based on the 64 antenna ports. Then, UE 1 measures CSI based on the first 4 horizontal antenna ports and the first 2 vertical antenna ports from the two polarizations (e.g., 16 ports). UE 2 measures CSI based on 8 horizontal antenna ports and 4 vertical antenna ports from the two polarizations (e.g., 64 ports). Therefore, CSI-RS transmitted from 16 ports (e.g., the first four horizontal antenna ports and the first two vertical antenna ports of the two polarizations) can be shared by UE 1 and UE 2.

[0087] Figure 12 Example 1200 of shared CSI-RS for UEs with different capabilities according to an embodiment is shown, and Figure 13 Example 1300 of block-wise port indexing compared to per-CSI-RS resource port indexing is shown. For block-wise port indexing, the antenna ports of the CSI-RS resource can be divided into blocks, and port indexing is performed starting with the antenna ports in the first block, followed by the antenna ports in the next block. For per-CSI-RS resource port indexing, port indexing is performed starting with the antenna ports in the first column, followed by the antenna ports in the next column. Therefore, when the number of blocks is 1, per-CSI-RS resource port indexing can be the same as block-wise port indexing.

[0088] In another embodiment, network entity 104 configures a first K port CSI-RS resource for the first UE and configures a second K port CSI-RS resource for the second UE. One antenna port CSI-RS resource, wherein network entity 104 is in relation to the second CSI-RS resource. The first CSI-RS resource is transmitted on the same K ports of the same antenna port in the same RE with the same signal. Network entity 104 configures the same scrambling identifier (ID) for these two CSI-RS resources. (See reference) Figure 13 In Example 1300, network entity 104 configures a first 16-port CSI-RS resource 1304 for a first UE (e.g., UE 1) and a second 64-antenna-port CSI-RS resource 1302 for a second UE (e.g., UE 2).

[0089] In some implementations, network entity 104 transmits the second CSI-RS resource based on a block-based antenna port index. Network entity 104 and UE 102 perform antenna port indexing for each block of K-port CSI-RS. Network entity 104 configures at least one of the following parameters for the block-based antenna port indexing: the number of antenna ports per antenna port block; the number of antenna port blocks; or the number of horizontal and vertical antenna ports per block. Network entity 104 can configure a port indexing scheme, for example, whether the port indexing is based on a per-CSI-RS resource port indexing scheme (1306) or a block-based port indexing scheme (1308). Reference Figure 13 For example, network entity 104 transmits the second CSI-RS resource based on block antenna port index 1308. Network entity 104 and UE 102 perform antenna port indexing for block 1308. In block 1308, network entity 104 configures 16 ports based on the block port indexing scheme.

[0090] Figure 13 Example 1300 of a block-based port index compared to a per-CSI-RS resource port index is shown, and Figures 14 to 15 Examples 1400 and 1500 of CSI measurements based on multiple CSI-RS resources are shown.

[0091] In another embodiment, network entity 104 can configure one CSI-RS resource with K antenna ports for the first UE, and configure M CSI-RS resources with different antenna ports for different resources. (See reference...) Figure 14 For example, network entity 104 configures CSI-RS resource 1404 with 16 antenna ports for a first UE (e.g., UE 1) and CSI-RS resource 1402 with 64 antenna ports for a second UE (e.g., UE 2). Network entity 104 spans... Each antenna port transmits M CSI-RS resources. In one example, network entity 104 configures each resource... A CSI-RS resource has K antenna ports. In another example, network entity 104 configures different numbers of antenna ports for different CSI-RS resources. For example, network entity 104 can configure M=2 CSI-RS resources, where the first CSI-RS resource is configured with K antenna ports, and the second CSI-RS resource is configured with... One antenna port.

[0092] In some implementations, network entity 104 transmits one of the M CSI-RS resources based on the same transmission behavior as the CSI-RS resources configured for the first UE. (See reference) Figure 14 Network entity 104 configures four CSI-RS resources (e.g., CSI-RS resource 1 1406A, CSI-RS resource 2 1406B, CSI-RS resource 3 1406C, and CSI-RS resource 4 1406D) with an equal number of ports (e.g., 16 ports) in each resource. Network entity 104 transmits CSI-RS resource 1 1406A based on the same transmission behavior as CSI-RS resource 1404 configured for the first UE (e.g., UE 1). Reference Figure 15 Example 1500, for instance, network entity 104 configures CSI-RS resource 1504 with 16 antenna ports for a first UE (e.g., UE 1) and CSI-RS resource 1502 with 64 antenna ports for a second UE (e.g., UE 2). Figure 14 Unlike Example 1400, network entity 104 configures two CSI-RS resources with different numbers of ports in each resource (e.g., CSI-RS resource 1 1506A, CSI-RS resource 2 1506B). For example, CSI-RS resource 1 1506A has 16 ports, and CSI-RS resource 2 1506B has 48 ports. Network entity 104 transmits CSI-RS resource 1 1506A based on the same transmission behavior as CSI resource 1504 configured for the first UE (e.g., UE 1).

[0093] Network entity 104 configures at least one of the following parameters to the same value for M CSI-RS resources: bandwidth, subcarrier, periodicity, Transmission Configuration Indicator (TCI) state, symbol, CDM group, CDM type, frequency domain density, and power offset between CSI-RS and the Physical Downlink Shared Channel (PDSCH). Network entity 104 may transmit CSI-RS resources within one time slot or S consecutive time slots (e.g., S = 2). Therefore, UE 102 should expect network entity 104 to configure at least one of the following parameters to the same value for M CSI-RS resources: bandwidth, subcarrier, periodicity, TCI state, symbol, CDM group, CDM type, frequency domain density, and power offset between CSI-RS and PDSCH. UE 102 may further expect network entity 104 to transmit CSI-RS resources within one time slot or S consecutive time slots (e.g., S = 2).

[0094] In some implementations, network entity 104 configures the number of horizontal and vertical antenna ports for each of the M CSI-RS resources, and based on... Each antenna port is used to configure the codebook. Network entity 104 can configure the configured CSI-RS resources. The antenna port multiplexing order in each antenna port. Network entity 104 can configure the number of horizontal CSI-RS resources and the number of vertical resources, and network entity 104 configures the vertical and horizontal positions of each CSI-RS resource by configuring the vertical resource index and the horizontal resource index. Then, UE 102 can determine The number of horizontal and vertical antenna ports for each antenna port, and the location of the antenna ports for each CSI-RS resource, are determined, and CSI is calculated based on the configured codebook.

[0095] In some other implementations, network entity 104 is Each antenna port is configured with the number of horizontal and vertical antenna ports, and an antenna port index is configured for each antenna port in each of the M CSI-RS resources. Then, UE 102 can determine the location of the antenna ports for each CSI-RS resource and calculate the CSI based on the configured codebook. In one example, network entity 104 configures for each CSI-RS resource... The bitmap for the unit digit, where the first state indicator of bit x comes from... Antenna port x of each antenna port was not transmitted in this CSI-RS resource, and the second status indication of bit x comes from Antenna port x of each antenna port is transmitted in this CSI-RS resource. The inverse operation of the first and second states of bit x can also be used as another example.

[0096] Figures 2 to 15 This illustrates various aspects of a CSI report based on CSI-RS employing overhead reduction techniques. Figures 16 to 17 Showing the implementation Figures 2 to 15 One or more aspects of the method. In particular, Figure 16 The diagram shows the pair of UE 102. Figures 2 to 15 One or more aspects of the implementation. Figure 17 104 pairs of network entities are shown. Figures 2 to 15 One or more aspects of the implementation.

[0097] Figure 16 A flowchart 1600 illustrates a method for wireless communication at the UE. (Reference) Figures 1 to 15 This method can be performed by UE 102. In an embodiment, UE 102 can send a UE capability report (1602) to network entity 104. For example, refer to... Figure 3 UE 102 may send 302 to network entity 104 to support UE capabilities with resource mapping modes featuring reduced CSI-RS overhead. The UE capability report indicates at least one of the following: the FD density supported by CSI-RS, the FDM scheme supported by the CDM group of CSI-RS, the TDM scheme supported by the CDM group of CSI-RS, the supported FD-OCC length, the supported TD-OCC length, the minimum number of REs per subband daily line port for PM, or the minimum number of REs per subband daily line port for CQI.

[0098] In an embodiment, UE 102 may receive 1604 configurations from network entity 104 for at least one of the following: CSI report, CMR associated with resource mapping mode, or subband size of CSI-RS. For example, refer to Figure 3 UE 102 can receive 304 from network entity 104 to enable resource mapping mode with reduced CSI-RS overhead and / or configure subband size RRC configuration.

[0099] In this embodiment, UE 102 can receive 1606 a trigger indication for a CSI report from network entity 104. For example, refer to Figure 3 UE 102 can receive a 306 MAC CE or DCI from network entity 104 to activate or trigger a CSI report. For semi-persistent CSI-RS or aperiodic CSI-RS, network entity 104 can send a MAC CE or DCI to activate or trigger a CSI-RS.

[0100] In one embodiment, UE 102 receives 1608 CSI-RS from network entity 104 on CMR, which is configured based on a resource mapping pattern associated with the number of antenna ports for CSI-RS at or above a threshold level. For example, refer to Figure 3 UE 102 receives 308 CSI-RS resources from network entity 104 based on the configured resource mapping pattern. UE 102 measures CSI based on the received CSI-RS resources. UE 102 can further determine the CSI of each subband based on the configured subband size.

[0101] In some examples, UE 102 receives 1608A CSI-RS from network entity 104 based on different CDM groups of CSI-RS located in different RBs (see, for example, see...). Figure 4 , Figure 5 and Figure 6 In some other examples, UE 102 receives 1608B CSI-RS from network entity 104 based on different CDM groups of CSI-RS located in different time slots (see, for example, [link to relevant documentation]). Figure 7 , Figure 8 , Figure 9 and Figure 10 In a further example, UE 102 receives 1608C public CSI-RS from network entity 104 on CMR (see, for example, see...). Figure 12 , Figure 13 , Figure 14 and Figure 15 ).

[0102] In one embodiment, UE 102 sends a 1610 CSI report to network entity 104, which includes measurement information associated with the resource mapping pattern of CSI-RS. For example, refer to... Figure 3 UE 102 sends a CSI report based on CSI-RS and CSI report configuration to network entity 104 via PUSCH or PUCCH.

[0103] Figure 16 A method from the UE side of the wireless communication link is described, while Figure 17 A method from the network side of a wireless communication link is described.

[0104] Figure 17 This is a flowchart (1700) illustrating a method for wireless communication at a network entity. (Reference) Figures 1 to 15 The method can be performed by one or more network entities 104, which may correspond to a base station or a unit of a base station, such as RU106, DU108 and / or CU110.

[0105] In this embodiment, network entity 104 can receive a UE capability report (1702) from UE 102. For example, refer to... Figure 3 Network entity 104 can receive 302 from UE 4 to support UE capabilities with resource mapping modes featuring reduced CSI-RS overhead. The UE capability report indicates at least one of the following: the FD density supported by CSI-RS, the FDM scheme supported by the CDM group of CSI-RS, the TDM scheme supported by the CDM group of CSI-RS, the supported FD-OCC length, the supported TD-OCC length, the minimum number of REs per subband daily line port for PM, or the minimum number of REs per subband daily line port for CQI.

[0106] In an embodiment, network entity 104 may send 1704 to UE 102 a configuration for at least one of the following: CSI report, CMR associated with resource mapping mode, or subband size of CSI-RS. For example, refer to Figure 3 Network entity 104 can send 304 to UE 102 to enable resource mapping mode with reduced CSI-RS overhead and / or configure RRC configuration for subband size.

[0107] In an embodiment, network entity 104 may send a 1706 trigger indication for a CSI report to UE 102. For example, refer to Figure 3 Network entity 104 can send a 306 MAC CE or DCI to UE 102 to activate or trigger a CSI report. For semi-persistent CSI-RS or aperiodic CSI-RS, network entity 104 can send a MAC CE or DCI to activate or trigger a CSI-RS.

[0108] In one embodiment, network entity 104 sends 1708 CSI-RS to UE 102 on a CMR, which is configured based on a resource mapping pattern associated with the number of antenna ports for CSI-RS at or above a threshold level. For example, refer to... Figure 3 Network entity 104 sends 308 CSI-RS resources to UE 102 based on the configured resource mapping mode. UE 102 measures CSI based on the received CSI-RS resources. UE 102 can further determine the CSI of each subband based on the configured subband size.

[0109] In some examples, network entity 104 sends 1708A CSI-RS to UE 102 based on different Code Division Multiplexing (CDM) groups of CSI-RS located in different RBs (see, for example, see...). Figure 4 , Figure 5 and Figure 6In some other examples, network entity 104 sends 1708B CSI-RS to UE 102 based on different Code Division Multiplexing (CDM) groups of CSI-RS located in different time slots (see, for example, [link to relevant documentation]). Figure 7 , Figure 8 , Figure 9 and Figure 10 In some further examples, network entity 104 sends 1708C public CSI-RS shared by multiple UEs, including UE 102 (see, for example, [link to relevant documentation]). Figure 12 , Figure 13 , Figure 14 and Figure 15 ).

[0110] In this embodiment, network entity 104 receives a 1710 CSI report from UE 102, which includes measurement information associated with the resource mapping pattern of the CSI-RS. For example, refer to... Figure 3 Network entity 104 receives CSI reports based on CSI-RS and CSI report configuration from UE 102 via PUSCH or PUCCH.

[0111] like Figure 18 The described UE equipment 1802 can execute the method of flowchart 1600. For example... Figure 19 One or more network entities 104 described can execute the methods of flowchart 1700.

[0112] Figure 18 Illustration 1800 illustrates an example of a hardware implementation of UE device 1802. UE device 1802 may be UE 102, a component of UE 102, or may implement UE functions. UE device 1802 may include an application processor 1806, which may have on-chip memory 1806'. In the example, application processor 1806 may be coupled to a secure digital (SD) card 1808 and / or a display 1810. Application processor 1806 may also be coupled to a sensor module 1812, a power supply 1814, an additional memory module 1816, a camera 1818, and / or other related components.

[0113] The UE equipment 1802 may further include a wireless baseband processor 1826, which may be referred to as a modem. The wireless baseband processor 1826 may have on-chip memory 1826'. Together with and similarly to the application processor 1806, the wireless baseband processor 1826 may also be coupled to a sensor module 1812, a power supply 1814, an additional memory module 1816, a camera 1818, and / or other related components. The wireless baseband processor 1826 may be additionally coupled to one or more Subscriber Identity Module (SIM) cards 1820 and / or one or more transceivers 1830 (e.g., wireless RF transceivers).

[0114] Within one or more transceivers 1830, the UE equipment 1802 may include a Bluetooth module 1832, a WLAN module 1834, an SPS module 1836 (e.g., a GNSS module), and / or a cellular module 1838. The Bluetooth module 1832, WLAN module 1834, SPS module 1836, and cellular module 1838 may each include an on-chip transceiver (TRX), or in some cases, only a transmitter (TX) or only a receiver (RX). The Bluetooth module 1832, WLAN module 1834, SPS module 1836, and cellular module 1838 may each include a dedicated antenna and / or utilize antenna 1840 to communicate with one or more other nodes. For example, UE equipment 1802 can communicate with another UE (e.g., sidelink communication) and / or with network entity 104 (e.g., uplink / downlink communication) via transceiver 1830 and antenna 1840, wherein network entity 104 may correspond to a base station or a unit of a base station (such as RU 106, DU 108 or CU 110).

[0115] The wireless baseband processor 1826 and application processor 1806 may each include computer-readable media / memory 1826' and 1806', respectively. An additional memory module 1816 may also be considered a computer-readable media / memory. Each computer-readable media / memory 1826', 1806', and 1816 may be non-transitory. The wireless baseband processor 1826 and application processor 1806 may each be responsible for general processing, including executing software stored on the computer-readable media / memory 1826', 1806', and 1816. This software, when executed by the wireless baseband processor 1826 / application processor 1806, causes the wireless baseband processor 1826 / application processor 1806 to perform the various functions described herein. The computer-readable media / memory may also be used to store data manipulated by the wireless baseband processor 1826 / application processor 1806 during software execution. The wireless baseband processor 1826 / application processor 1806 may be a component of UE 102. UE equipment 1802 may be a processor chip (e.g., a modem and / or application) and includes only the wireless baseband processor 1826 and / or the application processor 1806. In other examples, UE equipment 1802 may be the entire UE 102 and may include additional modules for equipment 1802.

[0116] like Figure 1 The discussion and reference Figure 16 Implemented, the reporting component 140 is configured to: receive a CSI-RS from a network entity on a CMR, the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; and send a CSI report to the network entity, the report including measurement information associated with the resource mapping mode of the CSI-RS.

[0117] Reporting component 140 may be located within application processor 1806 (e.g., at 140a), within wireless baseband processor 1826 (e.g., at 140b), or within both application processor 1806 and wireless baseband processor 1826. Reporting components 140a to 140b may be one or more hardware components specifically configured to perform the stated process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for use by one or more processors, or a combination thereof.

[0118] Figure 19Figure 1900 illustrates an example of a hardware implementation of one or more network entities 104. The one or more network entities 104 may be a base station, a component of a base station, or may implement base station functions. The one or more network entities 104 may include at least one of RU 106, DU 108, or CU 110, or may correspond to at least one of RU 106, DU 108, or CU 110. CU 110 may include a CU processor 1946, which may have on-chip memory 1946'. In some aspects, CU 110 may further include an additional memory module 1956 and / or a communication interface 1948, both of which may be coupled to the CU processor 1946. CU 110 may communicate with DU 108 via a midhaul link 162—such as an F1 interface between the communication interface 1948 of CU 110 and the communication interface 1928 of DU 108.

[0119] DU 108 may include a DU processor 1926, which may have on-chip memory 1926'. In some aspects, DU 108 may further include an additional memory module 1936 and / or a communication interface 1928, both of which may be coupled to the DU processor 1926. DU 108 may communicate with RU 106 via a frontlink 160 between DU 108's communication interface 1928 and RU 106's communication interface 1908.

[0120] RU 106 may include an RU processor 1906, which may have on-chip memory 1906'. In some aspects, RU 106 may further include an additional memory module 1916, a communication interface 1908, and one or more transceivers 1930, all of which may be coupled to the RU processor 1906. RU 106 may further include an antenna 1940, which may be coupled to one or more transceivers 1930, such that RU 106 can communicate with UE 102 via the antenna 1940 through one or more transceivers 1930.

[0121] On-chip memories 1906', 1926', 1946' and additional memory modules 1916, 1936, 1956 can each be considered as computer-readable media / memory. Each computer-readable medium / memory can be non-transitory. Each of processors 1906, 1926, 1946 is responsible for general processing, including executing software stored on the computer-readable medium / memory. When executed by the corresponding processor 1906, 1926, 1946, the software causes the processor 1906, 1926, 1946 to perform the various functions described herein. The computer-readable medium / memory can also be used to store data manipulated by the processors 1906, 1926, 1946 during software execution. In the example, configuration component 150 may be located at any of one or more network entities 104, such as at CU 110; at both CU 110 and DU 108; at each of CU 110, DU 108 and RU 106; at DU 108; at both DU 108 and RU 106; or at RU 106.

[0122] like Figure 1 The discussion and reference Figure 17 Implemented, configuration component 150 is configured to: send a CSI-RS to UE 102 on a CMR, the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; and receive a CSI report from UE 102, the report including measurement information associated with the resource mapping mode of the CSI-RS.

[0123] Configuration component 150 may be located within one or more processors of one or more network entities 104, such as RU processor 1906 (e.g., at 150a), DU processor 1926 (e.g., at 150b), and / or CU processor 1946 (e.g., at 150c). Configuration components 150a-150c may be one or more hardware components specifically configured to execute the stated process / algorithm, implemented by one or more processors 1906, 1926, 1946 configured to execute the stated process / algorithm, and stored in a computer-readable medium for use by one or more processors 1906, 1926, 1946, or combinations thereof.

[0124] The specific order or hierarchy of boxes in the processes and flowcharts disclosed herein is an example of the exemplary methods. Therefore, the specific order or hierarchy of boxes in the processes and flowcharts can be rearranged. Some boxes can also be combined or deleted. Dashed lines may indicate optional elements of the diagrams. The appended method claims present elements of various boxes in the exemplary order and are not limited to the specific order or hierarchy presented in the claims, processes, and flowcharts.

[0125] The detailed descriptions presented herein, in conjunction with accompanying drawings, depict various configurations, but do not represent the only configurations in which the concepts described herein can be practiced. These detailed descriptions include specific details used to provide a comprehensive explanation of the various concepts. However, these concepts can be practiced without using these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0126] Various aspects of wireless communication systems (such as telecommunications systems) are presented with reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, call flows, systems, algorithms, etc. (collectively, "elements"). These elements can be implemented using electronic hardware, computer software, or a combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and design constraints imposed on the overall system.

[0127] An element, or any part of an element, or any combination of elements, can be implemented as a “processing system” including one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, system-on-a-chip (SoCs), baseband processors, field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other similar hardware configured to perform the various functionalities described throughout this disclosure. One or more processors in a processing system can execute software, which may be referred to as software, firmware, middleware, microcode, hardware description languages, or others. Software should be interpreted broadly as instructions, instruction sets, code, code segments, program code, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.

[0128] If the functions described herein are implemented in software, these functions may be stored on or encoded as one or more instructions or code on a computer-readable medium, such as a non-transitory computer-readable storage medium. Computer-readable media include computer storage media and may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures accessible by a computer. The storage medium can be any available medium accessible to a computer.

[0129] The aspects, implementations, and / or use cases described herein can be implemented across many different platform types, devices, systems, form factors, sizes, and package arrangements. For example, aspects, implementations, and / or use cases can be generated via integrated chip implementations and other devices based on non-modular components, such as end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail / purchasing devices, medical devices, devices supporting artificial intelligence (AI), devices supporting machine learning (ML), etc. The scope of aspects, implementations, and / or use cases can range from chip-level or modular components to non-modular or non-chip-level implementations, and further to aggregated, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more of the technologies described herein.

[0130] Apparatus incorporating the aspects and features described herein may also include additional components and features for implementing and practicing the claimed and described aspects and features. For example, the transmission and reception of wireless signals necessarily include numerous components for analog and digital purposes, such as hardware components, antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc. The techniques described herein can be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated or decomposed components, end-user devices, etc., in various configurations.

[0131] The description herein is provided to enable those skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not limited to the aspects described herein, but should be interpreted in light of the full scope of this disclosure consistent with the language of the claims.

[0132] Unless explicitly stated otherwise, references to singular elements do not imply "one and only one," but rather "one or more." Terms such as "if," "when," and "at" do not imply an immediate temporal relationship or response. That is, these phrases (e.g., "when") do not imply an immediate action in response to the occurrence of an action or during the occurrence of an action, but simply imply that an action will occur if a certain condition is met, without requiring a specific or immediate temporal constraint on the occurrence of the action. The terms "may," "may," and "can" as used in this disclosure generally carry certain connotations. For example, "may" refers to a permissible feature that may or may not occur, "may" refers to a feature that is likely to occur, and "can" refers to a capability (e.g., being able to). The phrase "for example" generally carries a similar connotation to "may," and therefore, "may" is sometimes excluded from sentences that include "for example" or other similar phrases.

[0133] Unless otherwise expressly stated, the term "some" means one or more. Combinations such as "at least one of A, B, or C" or "one or more of A, B, or C" include any combination of A, B, and / or C, such as A and B, A and C, B and C, or A and B and C, and may include multiple A, multiple B, and / or multiple C, or may include only A, only B, or only C. A set should be interpreted as a set of elements having one or more elements. Terms or articles such as "a," "an," and / or "the" may refer to one of the items, features, elements, etc., following that term or article, or may refer to more than one of the items, features, elements, etc., following that term or article. For example, the expression "a small component" does not exclude references to multiple components, because "multiple components" necessarily includes "a small component." Therefore, the expression "a small component" can be interpreted as "at least one component," or similarly, as "one or more components."

[0134] Unless otherwise explicitly indicated, ordinal terms such as “first” and “second” do not necessarily imply order in time, sequence, numerical value, etc., but are used to distinguish different instances of the term or phrase that follows each ordinal term.

[0135] As used in the specification and drawings, reference numerals are sometimes cross-referenced across drawings to indicate the same or similar features. Features that are identical in multiple drawings can be labeled with the same reference numerals in multiple drawings. Features that are similar but not identical across multiple drawings can be labeled with reference numerals that have different leading numerals but share one or more of the same trailing numerals (e.g., 206, 306, 406, etc., can refer to similar features in the drawings). Therefore, the same numerals can refer to the same actions.

[0136] Structural and functional equivalents of elements of all aspects described throughout this disclosure, known or subsequently learned by those skilled in the art, are expressly incorporated herein by reference and are covered by the claims. The terms “module,” “mechanism,” “element,” “device,” etc., may not be substitutes for the term “component.” Therefore, no claim element shall be construed as means plus function unless explicitly stated using the phrase “component for…”. As used herein, the phrase “based on” should not be construed as a reference to a closed set of information, one or more conditions, one or more factors, etc. In other words, unless expressly stated otherwise, the phrase “based on A” (where “A” can be information, conditions, factors, etc.) shall be construed as “at least based on A”.

[0137] The following examples are illustrative only and can be combined with other examples or teachings described herein without limitation.

[0138] Example 1 is a method for wireless communication at a UE, the method comprising: receiving a CSI-RS from a network entity on a CMR, the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; and sending a CSI report to the network entity, the CSI report including measurement information associated with the resource mapping mode of the CSI-RS.

[0139] Example 2 may be combined with Example 1 and further includes receiving configuration from the network entity for at least one of the following: the CSI report, the CMR associated with the resource mapping mode, or the subband size of the CSI-RS.

[0140] Example 3 may be combined with any of Examples 1 to 2 and further includes: the resource mapping mode is based on at least one of the following: a first reduction of CSI-RS resources in the frequency domain, a second reduction of CSI-RS resources in the time domain, or the CSI-RS being associated with a common CSI-RS shared by a plurality of UEs including the UE.

[0141] Example 4 can be combined with Example 3 and further includes: the first reduction of the CSI-RS resources in the frequency domain includes: receiving the CSI-RS from the network entity based on different CDM groups of the CSI-RS located in different RBs.

[0142] Example 5 can be combined with Example 4 and further includes: the measurement information includes: CSI based on the number of REs for each antenna port of the CSI-RS being greater than or equal to a predetermined number of the subbands.

[0143] Example 6 can be combined with Example 3 and further includes: the second reduction of the CSI-RS resources in the time domain includes: receiving the CSI-RS from the network entity based on different CDM groups of the CSI-RS located in different time slots.

[0144] Example 7 can be combined with Example 6 and further includes: the measurement information is based on the CSI-RS located in the different time slots.

[0145] Example 8 can be combined with Example 3 and further includes: receiving the CSI-RS from the network entity includes receiving the public CSI-RS on the CMR.

[0146] Example 9 may be combined with any of Examples 1 to 8 and further includes: receiving the CSI-RS on the CMR based on at least one of the following: the CMR is associated with the predetermined number of antenna ports, a first number of antenna ports measured in the horizontal direction, a second number of antenna ports measured in the 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 port index.

[0147] Example 10 can be combined with Example 9 and further includes: the CMR for receiving the CSI-RS is a subset of the CMRs associated with the CSI-RS.

[0148] Example 11 may be combined with any of Examples 1 to 10 and further includes: sending a UE capability report to the network entity indicating at least one of the following: the FD density supported by the CSI-RS, the FDM scheme supported by the CDM group of the CSI-RS, the TDM scheme supported by the CDM group of the CSI-RS, the supported FD-OCC length, the supported TD-OCC length, the minimum number of REs per subband daily line port for PMI, or the minimum number of REs per subband daily line port for CQI.

[0149] Example 12 may be combined with any of Examples 1 to 11 and further includes: the resource mapping mode indicating at least one of the following: RB index for each CDM group in the CDM group and subcarriers in the RB, time slot index for each CDM group in the CDM group and start symbol index within the time slot, antenna port index scheme, CDM length for each CDM group in the CDM group, CDM type for each CDM group in the CDM group, or subband size configuration based on the supported FD density of the CMR.

[0150] Example 13 may be combined with any of Examples 1 to 12 and further includes receiving a trigger indication for the CSI report from the network entity.

[0151] Example 14 is a method for wireless communication at a UE, the method comprising: transmitting a CSI-RS to the user equipment on a CMR, the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; and receiving a CSI report from the UE, the CSI report including measurement information associated with the resource mapping mode of the CSI-RS.

[0152] Example 15 may be combined with Example 14 and further includes sending configuration to the UE for at least one of the following: the CSI report, the CMR associated with the resource mapping mode, or the subband size of the CSI-RS.

[0153] Example 16 may be combined with any of Examples 14 to 15 and further includes: the resource mapping mode reduces CSI-RS overhead based on at least one of the following: a first reduction of CSI-RS resources in the frequency domain, a second reduction of CSI-RS resources in the time domain, or the CSI-RS is a common CSI-RS of a plurality of UEs including the UE.

[0154] Example 17 can be combined with Example 16 and further includes: transmitting the CSI-RS includes transmitting the CSI-RS to the UE based on different CDM groups of the CSI-RS located in different RBs.

[0155] Example 18 can be combined with Example 17 and further includes: the measurement information includes: CSI based on the number of REs for each antenna port of the CSI-RS being greater than or equal to a predetermined number of the subbands.

[0156] Example 19 may be combined with any of Examples 14 to 18 and further includes: transmitting the CSI-RS includes transmitting the CSI-RS to the UE based on different CDM groups of the CSI-RS located in different time slots.

[0157] Example 20 can be combined with Example 19 and further includes: the measurement information is based on the CSI-RS in the different time slots.

[0158] Example 21 may be combined with any of Examples 14 to 20 and further includes: sending the CSI-RS includes sending a common CSI-RS shared by the multiple UEs, including the UE.

[0159] Example 22 may be combined with any of Examples 14 to 21 and further includes: receiving the CSI-RS on the CMR based on at least one of the following: the CMR is associated with the predetermined number of antenna ports, a first number of antenna ports measured in the horizontal direction, a second number of antenna ports measured in the 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 port index.

[0160] Example 23 can be combined with Example 22 and further includes: the configuration configures a first number of antenna ports for the first UE and a second number of antenna ports for the second UE.

[0161] Example 24 can be combined with Example 22 and further includes: the configuration further configures at least one of the following: the CMR having K antenna ports for the first UE, or a predetermined number of CMRs having different antenna ports.

[0162] Example 25 may be combined with any of Examples 1 to 24 and further includes: receiving from the UE a UE capability report indicating at least one of the following: the FD density supported by the CSI-RS, the FDM scheme supported by the CDM group of the CSI-RS, the TDM scheme supported by the CDM group of the CSI-RS, the supported FD-OCC length, the supported TD-OCC length, the minimum number of REs per subband daily line port for PMI, or the minimum number of REs per subband daily line port for CQI.

[0163] Example 26 may be combined with any of Examples 14 to 25 and further includes: sending another CSI-RS to another UE on another CMR, the other CMR being configured based on another resource mapping mode associated with a number of antenna ports for the other CSI-RS below the threshold.

[0164] Example 27 is an apparatus for implementing wireless communication as described in any one of Examples 1 to 26.

[0165] Example 28 is an apparatus for wireless communication, the apparatus including components for implementing the method as described in any one of Examples 1 to 26.

[0166] Example 29 is a non-transitory computer-readable medium storing computer-executable code that, when executed by a processor, causes the processor to implement the method as described in any one of Examples 1 to 26.

Claims

1. A method for wireless communication at a user equipment (UE) (102), comprising: On the channel measurement resource (CMR), a channel state information reference signal (CSI-RS) is received (308) from the network entity (104), the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; as well as Send (310) a Channel State Information (CSI) report to the network entity (104), the CSI report including measurement information associated with the resource mapping mode of the CSI-RS.

2. The method of claim 1, further comprising: Receive (304) configuration from the network entity (104) for at least one of the following: the CSI report, the CMR associated with the resource mapping mode, or the subband size of the CSI-RS.

3. The method according to any one of claims 1 to 2, wherein, The resource mapping mode is based on at least one of the following: The first reduction in CSI-RS resources in the frequency domain, The second reduction in CSI-RS resources in the time domain, or The CSI-RS is associated with a common CSI-RS shared by multiple UEs including the UE (102).

4. The method of claim 3, wherein, The first reduction of the CSI-RS resources in the frequency domain includes: The network entity (104) receives (308) the CSI-RS from the network entity (104) based on the different code division multiplexing (CDM) groups of the CSI-RS located in different resource blocks (RBs).

5. The method of claim 4, wherein the measurement information includes: CSI based on the number of resource elements (REs) for each antenna port of the CSI-RS being greater than or equal to a predetermined number of the subbands.

6. The method of claim 3, wherein, The second reduction of the CSI-RS resources in the time domain includes: The network entity (104) receives (308) the CSI-RS from the network entity (104) based on the different code division multiplexing (CDM) groups of the CSI-RS located in different time slots.

7. The method of claim 6, wherein, The measurement information is based on the CSI-RS located in the different time slots.

8. The method of claim 3, wherein receiving (308) the CSI-RS from the network entity (104) comprises: The common CSI-RS is received (308) on the CMR.

9. The method according to any one of claims 1 to 8, wherein, Receiving the CSI-RS on the CMR (308) is based on at least one of the following: The CMR is associated with the predetermined number of antenna ports. The first number of antenna ports measured in the horizontal direction. The second number of antenna ports measured in the vertical direction. The third number of total antenna ports in the horizontal direction The fourth number of total antenna ports in the vertical direction, or Antenna port index.

10. The method of any one of claims 1 to 9, further comprising: Send (302) a UE capability report indicating at least one of the following to the network entity (104): The frequency domain FD density supported for the CSI-RS, Frequency domain multiplexing FDM schemes supported by the CDM group used in the CSI-RS. The time-domain multiplexing (TDM) scheme supported by the CDM group used in the CSI-RS. Supported frequency domain orthogonal coverage code (FD-OCC) length, Supported time-domain orthogonal overlay code (TD-OCC) length, The minimum number of REs per sub-band daily line port used for the precoder matrix indicator PMI, or Minimum number of REs per subband daily line port for Channel Quality Indicator (CQI).

11. The method according to any one of claims 1 to 10, wherein, The resource mapping mode indicates at least one of the following: The RB index for each CDM group in the CDM group and the subcarriers in the RB. The time slot index and the starting symbol index within the time slot are used for each CDM group in the CDM group. Antenna port indexing scheme, The CDM length for each CDM group in the CDM group. The CDM type used for each CDM group in the CDM group, or Subband size configuration based on the supported FD density of the CMR.

12. A method for wireless communication at a network entity (104), comprising: On the Channel Measurement Resource (CMR), a Channel State Information Reference Signal (CSI-RS) is transmitted (308) to the User Equipment (102), the CMR being configured based on a resource mapping mode associated with the number of antenna ports for the CSI-RS at or above a threshold level; as well as The UE (102) receives (310) a Channel State Information (CSI) report, which includes measurement information associated with the resource mapping mode of the CSI-RS.

13. The method of claim 12, wherein sending the CSI-RS comprises: The CSI-RS is transmitted (308) to the UE (102) based on the different Code Division Multiplexing (CDM) groups of the CSI-RS located in different Resource Blocks (RBs).

14. The method of any one of claims 12 to 13, wherein sending the CSI-RS comprises: The CSI-RS is transmitted (308) to the UE (102) based on the different Code Division Multiplexing (CDM) groups of the CSI-RS located in different time slots.

15. The method of any one of claims 12 to 14, wherein transmitting the CSI-RS comprises: Send (308) a common CSI-RS shared by the multiple UEs, including the UE.

16. The method of any one of claims 12 to 15, further comprising: On another CMR, another CSI-RS is sent (308) to another UE (102), the other CMR being configured based on another resource mapping mode associated with the number of antenna ports for the other CSI-RS being below the threshold.

17. An apparatus for wireless communication, the apparatus comprising a memory, a transceiver, and a processor, the processor being coupled to the memory and the transceiver, the apparatus being configured to implement the method as claimed in any one of claims 1 to 16.

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