Patent Description:
Aspects of the present disclosure related generally to wireless communications systems, and more particularly, to transmitting channel state information (CSI) reference signals (CSI-RSs) in a new radio (NR) wireless network.

A wireless communication network may include a number of Node Bs that can support communication for a number of user equipments (UEs). A UE may communicate with a Node B via the downlink and uplink. The downlink (or forward link) refers to the communication link from the Node B to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the Node B.

An example of an emerging telecommunication standard is new radio (NR, e.g., <NUM> radio access). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) as well as support beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

Document <NPL>. The contribution proposes that the number of REs used by CSI-RS should be configurable and the combination of the RE configuration and number REs should be UE specific. In particular, it proposes that at least three configurations should be supported, namely, <NUM> symbol by Y subcarrier, X subcarrier by X symbol and Y symbols by <NUM> subcarrier. The CSI-RS can be transmitted always with a reference numerology or with the same numerology as the PDSCH of the UE.

Document <NPL>. The configurations are designed by aggregating existing <NUM> ports CSI-RS configurations to support {<NUM>, <NUM>, <NUM>, <NUM>} CSI-RS ports with minimal specification changes. An orthogonal cover code (OCC) sequence should not be extended over <NUM>, in order to guarantee the channel estimation accuracy.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer program products for new radio (NR) (new radio access technology) cell measurement. NR may include Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM>), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and mission critical targeting ultra reliable low latency communications (URLLC). For these general topics, different techniques are considered, such as coding, low-density parity check (LDPC), and polar. NR cell may refer to a cell operating according to the new air interface or fixed transport layer. A NR Node B (e.g., <NUM> Node B) may correspond to one or multiple transmission reception points (TRPs).

NR cells can be configured as access cell (ACells) or data only cells (DCells). For example, the RAN (e.g., a central unit or distributed unit) can configure the cells. DCells may be cells used for carrier aggregation or dual connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases DCells may not transmit synchronization signals-in some case cases DCells may transmit SS. TRPs may transmit downlink signals to UEs indicating the cell type. Based on the cell type indication, the UE may communicate with the TRP. For example, the UE may determine TRPs to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

In some cases, the UE can receive measurement configuration from the RAN. The measurement configuration information may indicate ACells or DCells for the UE to measure. The UE may monitor/detect measurement reference signals from the cells based on measurement configuration information. In some cases, the UE may blindly detect MRS. In some cases the UE may detect MRS based on MRS-IDs indicated from the RAN. The UE may report the measurement results.

Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects.

<FIG> illustrates an example wireless network <NUM> in which aspects of the present disclosure may be performed. For example, the wireless network may be new radio or <NUM> network. UEs <NUM> may be configured to perform the operations <NUM> discussed in more detail below for processing CSI-RS, in accordance with aspects of the present disclosure. Node B <NUM> may comprise a transmission reception point (TRP) configured to perform the operations <NUM> discussed in more detail below for transmitting CSI-RS, in accordance with aspects of the present disclosure. The NR network may include the central unit. The new radio network <NUM> may comprise a central unit <NUM>. According to certain aspects, the UEs <NUM>, Node B <NUM> (TRP), and central unit <NUM> may be configured to perform operations related to measurement configuration, measurement reference signal transmission, monitoring, detection, measurement, and measurement reporting, which are described in greater detail below.

The system illustrated in <FIG> may be, for example, a long term evolution (LTE) network. The wireless network <NUM> may include a number of Node Bs (e.g., evolved NodeBs (eNB), <NUM> Node B, etc.) <NUM> and other network entities. A Node B may be a station that communicates with the UEs and may also be referred to as a base station, an access point, etc. A Node B and <NUM> Node B are other examples of stations that communicate with the UEs.

Each Node B <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used.

A Node B may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cell. A Node B for a macro cell may be referred to as a macro Node B. A Node B for a pico cell may be referred to as a pico Node B. A Node B for a femto cell may be referred to as a femto Node B or a home Node B. In the example shown in <FIG>, the Node Bs 110a, 110b and 110c may be macro Node Bs for the macro cells 102a, 102b and 102c, respectively. The Node B 110x may be a pico Node B for a pico cell 102x. The Node Bs 110y and 110z may be femto Node Bs for the femto cells 102y and 102z, respectively. A Node B may support one or multiple (e.g., three) cells.

A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a Node B or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a Node B). In the example shown in <FIG>, a relay station 110r may communicate with the Node B 110a and a UE 120r in order to facilitate communication between the Node B 110a and the UE 120r. A relay station may also be referred to as a relay Node B, a relay, etc..

The wireless network <NUM> may be a heterogeneous network that includes Node Bs of different types, e.g., macro Node Bs, pico Node Bs, femto Node Bs, relays, transmission reception points (TRPs), etc. These different types of Node Bs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network <NUM>. For example, macro Node Bs may have a high transmit power level (e.g., <NUM> Watts) whereas pico Node Bs, femto Node Bs and relays may have a lower transmit power level (e.g., <NUM> Watt).

For synchronous operation, the Node Bs may have similar frame timing, and transmissions from different Node Bs may be approximately aligned in time. For asynchronous operation, the Node Bs may have different frame timing, and transmissions from different Node Bs may not be aligned in time.

A network controller <NUM> may couple to a set of Node Bs and provide coordination and control for these Node Bs. The network controller <NUM> may communicate with the Node Bs <NUM> via a backhaul. The Node Bs <NUM> may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

A UE may also be referred to as a terminal, a mobile station, a subscriber unit, a station, etc. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a netbook, a smart book, etc. A UE may be able to communicate with macro Node Bs, pico Node Bs, femto Node Bs, relays, etc. In <FIG>, a solid line with double arrows indicates desired transmissions between a UE and a serving Node B, which is a Node B designated to serve the UE on the downlink and/or uplink. A dashed line with double arrows indicates interfering transmissions between a UE and a Node B.

LTE utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. For example, the spacing of the subcarriers may be <NUM> and the minimum resource allocation (called a 'resource block') may be <NUM> subcarriers (or <NUM>). Consequently, the nominal FFT size may be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM> for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM> megahertz (MHz), respectively. For example, a subband may cover <NUM> (i.e., <NUM> resource blocks), and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

A single component carrier bandwidth of <NUM> may be supported. Each radio frame may be <NUM> long and consist of <NUM> slots. In alternative embodiments, each slot may have a length of <NUM>. In NR, "slots" may also refer to "mini-slots," which may be one to two symbol periods long. Each slot may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each slot may be dynamically switched. Each slot may include DL and/or UL data as well as DL and/or UL control data. Beamforming may be supported and beam direction(s) may be dynamically configured. NR networks may include entities such as central units, distributed units, data nodes, access nodes, and access control nodes.

<FIG> shows an exemplary downlink (DL) frame structure used in a telecommunication systems (e.g., LTE). The transmission timeline for the downlink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., <NUM> milliseconds (ms)) and may be partitioned into <NUM> slots with indices of <NUM> through <NUM>. Each slot may include L symbol periods, e.g., <NUM> symbol periods for a normal cyclic prefix (as shown in <FIG>). Each resource block may cover N subcarriers (e.g., <NUM> subcarriers) in one slot.

The Node B may send a downlink control channel (e.g., a physical downlink control channel (PDCCH)) in the first M symbol periods of each slot (M=<NUM> in <FIG>). The downlink control channel may carry information on uplink and downlink resource allocation for UEs and power control information for uplink channels. The Node B may send a physical downlink shared channel (PDSCH) in the remaining symbol periods of each slot. The PDSCH may carry data for UEs scheduled for data transmission on the downlink. There may also be an uplink burst at the end of the slot.

The Node B may send the PDCCH to groups of UEs or in a unicast manner to specific UEs in certain portions of the system bandwidth. The Node B may send the PDSCH in a unicast manner to specific UEs in specific portions of the system bandwidth.

A UE may be within the coverage of multiple Node Bs. One of these Node Bs may be selected to serve the UE. The serving Node B may be selected based on various criteria such as received power, path loss, signal-to-noise ratio (SNR), etc..

<FIG> is a diagram <NUM> illustrating an example of an uplink (UL) frame structure in a telecommunications system (e.g., LTE). The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned resource blocks 310a, 310b to transmit control information to a Node B. The UE may also be assigned resource blocks 320a, 320b to transmit data to the Node B. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may hop across frequency.

<FIG> illustrates example components of the base station/Node B <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. One or more components of the AP <NUM> and UE <NUM> may be used to practice aspects of the present disclosure. For example, antennas <NUM>, Tx/Rx <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the operations described herein and illustrated with reference to <FIG>.

<FIG> shows a block diagram of a design of a base station/Node B <NUM> and a UE <NUM>, which may be one of the base stations/Node Bs and one of the UEs in <FIG>. For a restricted association scenario, the base station <NUM> may be the macro Node B 110c in <FIG>, and the UE <NUM> may be the UE 120y.

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, etc. The data may be for the PDSCH, etc. The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal.

On the uplink, at the UE <NUM>, a transmit processor <NUM> may receive and process data (e.g., for the PUSCH) from a data source <NUM> and control information (e.g., for the PUCCH) from the controller/processor <NUM>. At the base station <NUM>, the uplink signals from the UE <NUM> may be received by the antennas <NUM>, processed by the modulators <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE <NUM>.

The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of various processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the base station <NUM> and the UE <NUM>, respectively.

<FIG> is a diagram <NUM> illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the Node B is shown with three layers: Layer <NUM>, Layer <NUM>, and Layer <NUM>. Layer <NUM> (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer <NUM>. Layer <NUM> (L2 layer) <NUM> is above the physical layer <NUM> and is responsible for the link between the UE and Node B over the physical layer <NUM>.

In the user plane, the L2 layer <NUM> includes a media access control (MAC) sublayer <NUM>, a radio link control (RLC) sublayer <NUM>, and a packet data convergence protocol (PDCP) <NUM> sublayer, which are terminated at the Node B on the network side. Although not shown, the UE may have several upper layers above the L2 layer <NUM> including a network layer (e.g., IP layer) that is terminated at the PDN gateway <NUM> on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer <NUM> provides multiplexing between different radio bearers and logical channels. The PDCP sublayer <NUM> also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between Node Bs. The RLC sublayer <NUM> provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer <NUM> provides multiplexing between logical and transport channels. The MAC sublayer <NUM> is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer <NUM> is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and Node B is substantially the same for the physical layer <NUM> and the L2 layer <NUM> with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer <NUM> in Layer <NUM> (L3 layer). The RRC sublayer <NUM> is responsible for obtaining radio resources (i.e., radio bearers) and for configuring the lower layers using RRC signaling between the Node B and the UE.

New radio (NR) may refer to radios configured to operate according a wireless standard, such as <NUM> (e.g. wireless network <NUM>). NR may include Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> and beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM> and higher), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and mission critical targeting ultra reliable low latency communications (URLLC).

NR cell may refer to a cell operating according in the NR network. A NR Node B (e.g., Node B <NUM>) may correspond to one or multiple transmission and reception points (TRPs). As used herein, a cell may refer to a combination of downlink (and potentially also uplink) resources. The linking between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information (SI) transmitted on the downlink resources. For example, system information can be transmitted in a physical broadcast channel (PBCH) carrying a master information block (MIB).

NR RAN architecture may include a central unit (CU) (e.g., central unit <NUM>). The CU may be an Access node controller (ANC). The CU terminates backhaul interface to a RAN core network (RAN-CN) and terminates backhaul interface to one or more neighbor RAN nodes. The RAN may include a distributed unit that may be one or more TRPs that may be connected to one or more ANCs (not shown). TRPs may advertise System Information (e.g., Global TRP ID), may include PDCP/RLC/MAC functions, may comprise one or more antenna ports, may be configured to individually (dynamic selection) or jointly (joint transmission) transmit to UEs, and may serve traffic to the UE.

<FIG> shows another exemplary transmission timeline <NUM> that may be used in a TDD system in which one or more aspects of the present disclosure may be practiced. The timeline <NUM> is divided into a plurality of slots <NUM> or <NUM>. A slot is a scheduling unit that has DL control, data, and UL control, as shown. A mini-slot is the smaller scheduling unit that <NUM> will support. A mini-slot can be as small as <NUM> or <NUM> OFDM symbols and can have DL control, data, and UL control. According to aspects of the present disclosure, slots in a TDD communications system may be UL-centric or DL-centric. An UL-centric slot is a slot with a majority of OFDM symbols of the slot used for UL transmission(s). An UL-centric slot typically has a few (e.g. <NUM>) DL symbols at the beginning, then a guard duration, then UL symbols. A DL-centric slot is a slot with a majority of OFDM symbols used for DL transmission. A DL-centric slot typically has most (e.g. <NUM>) of the first symbols used for DL transmissions, then a guard interval, then a few (e.g., <NUM>-<NUM>) UL symbols. The timeline <NUM> includes a plurality DL-centric slots <NUM> that have most symbols <NUM> dedicated to DL transmissions (e.g., from a BS to a UE) and a common UL burst <NUM> at the end with very limited resources dedicated to UL transmissions (e.g., from a UE to a BS). The timeline also includes a plurality of UL-centric slots <NUM> that each has a DL symbol <NUM> at the beginning of the slot, but the remaining symbols <NUM> of the slot are dedicated to UL transmissions. As seen in the UL slot 610b, the UL symbols <NUM> may be allocated to various users (e.g., UEs) for a variety of UL transmissions (e.g., OFDM PUSCH, SC-FDM PUSCH, SC-FDM PUCCH, OFDM PUCCH). Similarly, while not shown, the DL symbols <NUM> of a DL slot <NUM> may be allocated for a variety of DL transmissions (e.g., PDCCH, PDSCH) to one or more UEs.

According to aspects of the present disclosure, DL-centric slots and UL-centric slots may occur according to a ratio configurable by the network (e.g., a network controller). The ratio of DL-centric slots and UL-centric slots may be of the order of <NUM>:<NUM>, <NUM>:<NUM>, etc., i.e., there may be significantly more DL-centric slots than UL-centric slots in many wireless communications systems.

MIMO may be an important technology enabler for satisfying NR coverage and capacity requirements. The advantages of using MIMO come at the price of obtaining channel state information (CSI) at the transmission/reception point (TRP). The CSI has to be obtained at the TRP via UE feedback based on DL channel estimation by the UE(s), aided by CSI-RS transmitted by the TRP and processed by the UE(s).

<FIG> illustrates an exemplary resource block structure <NUM> showing a mapping of CSI-RSs to resource elements in an LTE communications system, according to aspects of the present disclosure. In an LTE communications system, up to <NUM> resource elements (REs) may be reserved for CSI-RS transmission in FDD. The <NUM> REs that may be reserved for CSI-RS transmission are shown at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> labeled as sets A through J of REs, with <NUM> REs per set. Sets A through J are capable of supporting <NUM> CSI-RSs, as shown in <FIG>. If a cell transmits CSI-RS using <NUM> CSI-RS ports, then the <NUM> CSI-RS ports may be multiplexed by size-<NUM> orthogonal cover codes (OCC) in the time domain. If a cell transmits CSI-RS using <NUM> CSI-RS ports, then the <NUM> CSI-RS ports may be multiplexed by applying size-<NUM> OCC in both the time and the frequency domain. Orthogonal cover codes (OCC) provide additional orthogonality between the CSI-RS ports.

According to aspects of the present disclosure, an NR TRP may determine a configuration of CSI-RSs in resource elements, transmit an indication of the determined configuration, and transmit the CSI-RSs according to the configuration. A UE may obtain the indication of the determined configuration, process CSI-RSs based on the indicated configuration to determine channel state information, and report the channel state information to the TRP. Operation of a massive MIMO wireless communication system heavily relies on a variety of procedures and mechanisms to provide channel state information (CSI) at the transmitter for achieving high beamforming and spatial multiplexing gains. The TRP receiving the CSI may then use the CSI for downlink scheduling by a BS.

According to aspects of the present disclosure, the provided techniques for mapping CSI-RSs to REs may support at least <NUM> ports while using a smaller footprint, in terms of transmission resources, than other techniques.

According to aspects of the present disclosure, the provided techniques for mapping CSI-RSs to REs may support both beamformed and non-precoded CSI-RS. Power boosting of CSI-RS may improve coverage for UEs in poor coverage conditions.

According to aspects of the present disclosure, the provided techniques for mapping CSI-RSs to REs may support both <NUM>-symbol-period and <NUM>-symbol-period slots, as well as mini-slots having a length in symbol periods from one to a slot-length minus one (e.g., <NUM>-<NUM> = <NUM> symbol period mini-slot or <NUM>-<NUM> = <NUM> symbol period mini-slot).

According to aspects of the present disclosure, the provided techniques for mapping CSI-RSs to REs may support CSI-RS resource pooling.

According to aspects of the present disclosure, the provided techniques for mapping CSI-RSs to REs may support transmissions using self-contained slots. A self-contained slot is a slot in which a TRP transmits a control channel scheduling an UL transmission (e.g., a PUSCH) or a DL transmission (e.g., a PDSCH) in the same slot. The data transmission occurs in the same slot, and if the data transmission was a DL transmission, then a UE that received the DL transmission transmits an acknowledgment (ACK) in the same slot. This is referred to as a self-contained slot because the TRP starts a transmission (e.g., the PDCCH) in a slot and receives an indication that the transmission was successful (e.g., the PUSCH or the ACK) in the same slot.

<FIG> illustrates example operations <NUM> for wireless communications by a TRP, according to aspects of the present disclosure. The operations <NUM> may be performed, for example, by BS <NUM> shown in <FIG>.

Operations <NUM> begin, at block <NUM> by determining a configuration of channel state information reference signals (CSI-RSs), wherein the configuration indicates a set of resource elements (REs) to be used for CSI-RSs and a first mapping of CSI-RS ports to the set of REs. For example, BS <NUM> determines a configuration of CSI-RSs (e.g., the configuration illustrated in <FIG>, described below), wherein the configuration indicates a set of REs to be used for CSI-RSs and a first mapping (e.g., the mapping shown in <FIG>) of CSI-RS ports to the set of REs.

At block <NUM>, operations <NUM> continue with sending an indication of the configuration of the CSI-RSs. Continuing the example from above, BS <NUM> sends (e.g., transmits) an indication (e.g., via radio resource control (RRC), layer <NUM> (L2), and/or layer <NUM> (L1) signaling) of the configuration of the CSI-RSs.

Operations <NUM> continue, at block <NUM>, with transmitting the CSI-RSs according to the determined configuration. Continuing the example from above, BS <NUM> transmits the CSI-RSs according to the configuration determined in block <NUM> (e.g., the configuration illustrated in <FIG>, described below).

<FIG> is a flowchart illustrating example operations <NUM> for wireless communications by a wireless node, according to aspects of the present disclosure. The operations <NUM> may be performed by, for example, a UE (e.g., UE <NUM>). Operations <NUM> may be considered UE-side operations performed to process CSI-RS transmitted in accordance with operations <NUM> described above.

Operations <NUM> begin, at block <NUM>, by the wireless node obtaining an indication of a configuration of channel state information reference signals (CSI-RSs) from a transmission and reception point (TRP), wherein the configuration indicates a set of resource elements (REs) to be used for CSI-RSs and a first mapping of CSI-RS ports to the set of REs. For example, UE <NUM>, shown in <FIG>, obtains (e.g., receives via RRC, L2, and/or L1 signaling) an indication of a configuration (e.g., the configuration illustrated in <FIG>) from a TRP (e.g., BS 110a, shown in <FIG>), wherein the configuration indicates a set of REs to be used for CSI-RSs and a first mapping of CSI-RS ports to the set of REs.

Operations <NUM> continue, at block <NUM>, by the wireless node processing CSI-RSs based on the indicated configuration to determine channel state information. Continuing the example from above, the UE <NUM> processes (e.g., measures) CSI-RSs based on the indicated configuration (from block <NUM>) to determine channel state information.

At block <NUM>, the UE reports the channel state information to the TRP. Continuing the example from above, the UE <NUM> reports (e.g., by transmitting a CSI report) the channel state information to the TRP (e.g., BS 110a, shown in <FIG>).

Control signaling can be used to indicate one symbol (self-contained CSI-RS symbol) or more than <NUM> symbol with OCC and possibly some combinations of one symbol and two symbols in a slot: for example, for a <NUM>-symbol slot, <NUM> pairs of CSI-RS symbols plus <NUM> CSI-RS symbol may be used.

In some cases, configurable orthogonal cover codes (OCC) may be applied in time and/or frequency. The OCC configuration may be indicated via higher-layer signaling (e.g., RRC), L2 signaling (e.g., a MAC CE), L1 signaling (e.g., a DCI) and/or any combination of RRC, L2, or L1 signaling.

In some cases, scalable numerology symbols for <NUM>-symbol CSI-RS may be used to create two virtual symbols, for example, by applying OCC in time (time domain OCC (TD-OCC)). For example, instead of transmitting one OFDM symbol with a first numerology, two OFDM symbols with a second numerology with double subcarrier spacing (SCS) and the same cyclic prefix (CP) overhead are transmitted. These two symbols can carry the CSI-RS using TD-OCC.

The location (in time domain) of CSI-RS may be determined relative to the end of the DL portion, when a self-contained slot is used. For example, if one OFDM symbol with CSI-RS is used, this symbol is implicitly understood that it is the latest (e.g., last) DL symbol in the DL burst. Similarly, if two or more symbols carrying CSI-RS are used, then the last two or more latest symbols of the DL burst are being used for CSI-RS. In this example, data shall not be multiplexed with CSI-RS on the same symbols.

As illustrated in <FIG>, with "<NUM>-symbol CSI-RS," a CSI-RS transmission may be self-contained in one OFDM symbol. According to some aspects of the present disclosure, a <NUM>-symbol CSI-RS may be a self-contained CSI-RS transmitted using interleaved frequency division multiplexing (IFDM) and/or code division multiplexing (CDM). As illustrated, the CSI-RS may be transmitted on uniformly distributed REs. The CSI-RS resources correspond to RE groups. Different CSI-RS ports may be separated by using different combs, labeled combs A, B, C, and D and shown at <NUM>, and/or using different cyclic-shifts of a common root constant amplitude zero autocorrelation (CAZAC) sequence (e.g., a Zadoff-Chu sequence). As illustrated, there are <NUM> ports. Comb A corresponds to frequencies <NUM>, <NUM>, and <NUM>. Likewise, comb B corresponds to frequencies <NUM>, <NUM>, and <NUM>; comb C corresponds to frequencies <NUM>, <NUM>, and <NUM>; and comb D corresponds to frequencies <NUM>, <NUM>, and <NUM>. A series of discrete, equally spaced elements in a spectrum may be referred to as a frequency comb.

<FIG> illustrate other examples of <NUM>-symbol CSI-RS transmission with frequency division multiplexing (FDM) and/or frequency division orthogonal cover codes (FD-OCC). As illustrated, the CSI-RS may be transmitted on a set of uniformly distributed RE groups. Each group may comprise two or more localized or distributed REs. Different CSI-RS ports may be separated by different sets of RE groups and further by applying orthogonal cover codes (OCC) to the REs in each group. In <FIG> , it can be seen that there are <NUM> CSI-RS configurations, A-F, with each set (e.g. set A, set B,. or set F) of CSI-RS ports being mapped to <NUM> REs that are located in a same time domain (e.g., OFDM symbol <NUM>) and adjacent each other (e.g., on consecutive subcarriers) in the frequency domain, as shown at <NUM>. This may result in a stronger correlation of each CSI when combining the CSI-RS resources. Resource configuration set A comprises ports <NUM> and <NUM> with size-<NUM> frequency domain orthogonal cover codes (FD-OCC2). Resource configuration set B comprises ports <NUM> and <NUM> with FD-OCC2. Resource configuration set C comprises ports <NUM> and <NUM> with FD-OCC2. Resource configuration set D comprises ports <NUM> and <NUM> with FD-OCC2. Resource configuration set E comprises ports <NUM> and <NUM> with FD-OCC2. Resource configuration set F comprises ports <NUM> and <NUM> with FD-OCC2. In <FIG>, it can be seen that there are <NUM> CSI-RS configurations at <NUM>, each CSI-RS resource or port being mapped to <NUM> RE.

<FIG> illustrate <NUM>-symbol CSI-RS, with each CSI-RS transmission using a pair of OFDM symbols with TD-OCC, in accordance with aspects of the present disclosure. A UE can be configured to further apply orthogonal cover codes (OCC) to two OFDM symbols. TD-OCC may be configurable for the <NUM>-symbol CSI-RS solution. The configuration can be either signaled using higher-layer signaling (e.g., RRC), L2 signaling (e.g., MAC CE), L1 signaling (e.g., DCI), and/or any combination of higher-layer signaling, L2 signaling, or L1 signaling. <FIG> illustrates an example of mapping CSI-RS with IFDM and/or CDM and TD-OCC at <NUM>. <FIG> illustrates an example of mapping CSI-RS with FDM and FD-OCC and/or TD-OCC at <NUM>.

<FIG> illustrate examples of multiple <NUM>-symbol CSI-RS transmissions in a slot, in accordance with aspects of the present disclosure. A UE may be configured with one or more OFDM symbols for <NUM>-symbol CSI-RS transmission. For example, in case of <NUM>-port CSI-RS, a UE may be configured with CSI-RS transmission on <NUM> OFDM symbols; one symbol may convey CSI-RS ports <NUM>-<NUM>, as shown at <NUM>, and the other symbol may convey CSI-RS ports <NUM>-<NUM>, as shown at <NUM>. In another example, the ports may be divided into twelve sets of CSI-RS resources, while still having a first symbol convey CSI-RS ports <NUM>-<NUM>, as shown at <NUM>, and another symbol conveying CSI-RS ports <NUM>-<NUM>, as shown at <NUM>.

<FIG> illustrates an example of a combination (e.g., a mix) of <NUM>-symbol and <NUM>-symbol CSI-RSs in a slot. In the illustrated example, a UE may be configured with one or more <NUM>-symbol and/or <NUM>-symbol CSI-RSs. For example, in case of a <NUM>-symbol slot, a UE can be configured w/ three <NUM>-symbol CSI-RSs with TD-OCC2, shosn at <NUM>, <NUM>, and <NUM>, and a <NUM>-symbol CSI-RS <NUM>. The configuration may be signaled using higher-layer signaling (e.g., RRC), L2 signaling (e.g., MAC CE), L1 signaling (e.g., DCI), and/or any combination of higher-layer signaling, L2 signaling, and L1 signaling. The configuration may indicate which symbols are used for <NUM>-symbol CSI-RS and which symbols are used for <NUM>-symbol CSI-RS. A <NUM>-symbol CSI-RS can be virtually split into <NUM>-symbol CSI-RS with TD-OCC2.

When only <NUM>-symbol is available, and TD-OCC is configured, then scaled numerology (double subcarrier spacing with the same CP overhead) may be used to create <NUM>-symbols with double the subcarrier spacing (SCS) and applying TD-OCC.

According to aspects of the present disclosure, similar techniques may be applied for CSI-RS in a mini-slot. A mini-slot is generally the minimum scheduling unit that can be as small as <NUM> OFDM symbol and up to slot_length-<NUM> (e.g., <NUM>-<NUM>=<NUM>) OFDM symbols. For all cases that the number of available CSI-RS symbols is odd, <NUM>-symbol and <NUM>-symbol CSI-RS designs may be mixed.

<FIG> illustrates an example of CSI-RS location in a self-contained slot. For low-latency applications, symbols carrying CSI-RS may be allocated relative to the "end" of the DL part of the slot, as shown at <NUM>. The same technique may be applied to aggregation of slots or mini-slots. CSI-RS and data may not be frequency division multiplexed in these symbols. If frequency division multiplexing of data and CSI-RS was supported, then data would appear in the last symbols, which would make the timeline processing and the fast-turnaround of the ACK difficult for the UE.

According to aspects of the present disclosure and as illustrated in <FIG>, TD-OCC may be used to ensure that no resources are left unused. For example, if <NUM> ports need to be supported, if no TD-OCC is used, then <NUM> ports will appear in one symbol, and <NUM> ports in the other symbol. Then, some resource elements may not be allowed to carry data, and therefore these resources are lost. As shown at <NUM> and <NUM>, eight ports may be supported in a set of eight REs, both without using TD-OCC, as at <NUM>, and using TD-OCC, as at <NUM>. If only six ports are to be supported by the same set of eight REs, then two REs remain unused if TD-OCC is not used, because six REs are used for the six CSI-RS and two REs <NUM> and <NUM> are not needed for CSI-RS, but cannot be used for data transmission (because data and CSI-RS frequency division multiplexing is not supported). However, using TD-OCC with CSI-RS uses all of the REs, as shown at <NUM>, while allowing a stronger correlation of each CSI when combining the CSI-RS.

For example, instructions for determining a maximum available transmit power of the UE, instructions for semi-statically configuring a first minimum guaranteed power available for uplink transmission to a first base station and a second minimum guaranteed power available for uplink transmission to a second base station, and instructions for dynamically determining a first maximum transmit power available for uplink transmission to the first base station and a second maximum transmit power available for uplink transmission to the second base station based, at least in part, on the maximum available transmit power of the UE, the first minimum guaranteed power, and the second minimum guaranteed power.

Claim 1:
A method (<NUM>) for wireless communications by a transmission reception point (<NUM>), comprising:
determining (<NUM>) a configuration of channel state information reference signals, CSI-RSs, wherein the configuration indicates a set of resource elements, REs, to be used for CSI-RSs and a first mapping of CSI-RS ports to the set of REs;
sending (<NUM>) an indication of the configuration of the CSI-RSs; and
transmitting (<NUM>) the CSI-RSs according to the determined configuration;
characterized in that:
the configuration indicates a combination of one orthogonal frequency division multiplexed, OFDM, symbol CSI-RSs and two OFDM symbols CSI-RSs in a slot.