Patent Description:
Aspects of the present disclosure relate generally to wireless communications systems, and more particularly, to dynamic multi-beam transmission for new radio (NR) technology multiple-input multiple-output (MIMO) communications.

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

An example of an emerging telecommunication standard is new radio (NR, e.g., <NUM>th Generation (<NUM>) radio access). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. Preferably, these improvements should be applicable to other multi--access technologies and the telecommunication standards that employ these technologies. Related art is disclosed in <CIT> and <CIT>.

The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes.

Techniques for dynamic multi-beam transmissions for new radio (NR) technology multiple-input multiple-output are described herein.

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) techniques targeting wide bandwidth (e.g. <NUM> beyond) communications, millimeter wave (mmW) techniques targeting high carrier frequency (e.g. <NUM>) communications, massive machine type communications (mMTC) techniques targeting non-backward compatible MTC techniques, and mission critical techniques targeting ultra reliable low latency communications (URLLC). For these general topics, different techniques are considered, including coding techniques such as low-density parity check (LDPC) coding, and polar coding. An NR cell may refer to a cell operating according to the new air interface or fixed transport layer. An NR NodeB (e.g., a <NUM> NodeB) may correspond to one or multiple transmission and reception points (TRPs).

NR cells can be configured as access cell (ACells) or data only cells (DCells). For example, a radio access network (RAN) (e.g., a central unit or a distributed unit) can configure the cells as ACells or DCells. 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 (SS)-in other cases DCells may transmit SS. A TRP of a DCell or an ACell may transmit downlink signals to UEs indicating the cell type of the cell that the TRP serves. Based on the cell type indication, a UE may communicate with the TRP. For example, a UE may determine TRPs to consider for cell selection, access, handover, and/or measurement based on cell types indicated by the TRPs.

In some cases, a 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 and/or detect measurement reference signals from the cells based on measurement configuration information. In some cases, the UE may blindly detect measurement reference signals (MRS). In some cases the UE may detect MRS based on MRS identifiers (MRS-IDs) indicated from the RAN. The UE may report the measurement results to the RAN via one or more TRPs.

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. The detailed description and drawings are merely illustrative of the disclosure rather than limiting and the scope of the disclosure is being defined by the appended claims and equivalents thereof.

edma2000 covers IS-<NUM>, IS-<NUM> and IS-<NUM> standards.

<FIG> illustrates an example wireless network <NUM> in which aspects of the present disclosure may be performed. For example, the wireless network may be a new radio or <NUM> network. UEs <NUM> may be configured to perform the operations <NUM>-<NUM>, discussed in more detail below with reference to <FIG>, for dynamic multi-beam communications in NR systems. NodeB <NUM> may comprise a transmission and reception point (TRP) configured to perform operations complementary to operations <NUM>-<NUM>. The new radio network <NUM> may comprise a central unit <NUM> configured to coordinate communications between TRPs, such as coordinated multi-point (CoMP) operations. According to certain aspects, the UEs <NUM>, NodeBs (TRPs) <NUM>, and central unit <NUM> may be configured to perform operations related to measuring and selecting beams for multiple-input multiple-output communications, which are described in greater detail below.

Each NodeB (TRP) <NUM> may provide communication coverage for a particular geographic area. In 3GPP (e.g., <NUM>, <NUM>, and NR) communications systems, the term "cell" can refer to a coverage area of a NodeB (e.g., a TRP) and/or a NodeB subsystem (e.g., a TRP) serving this coverage area, depending on the context in which the term is used.

A NodeB (e.g. a TRP) may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cell. A NodeB for a macro cell may be referred to as a macro NodeB. A NodeB for a pico cell may be referred to as a pico NodeB. A NodeB for a femto cell may be referred to as a femto NodeB or a home NodeB. In the example shown in <FIG>, the NodeBs 110a, 110b and 110c may be macro NodeBs for the macro cells 102a, 102b and 102c, respectively. The NodeB 110x may be a pico NodeB for a pico cell 102x. The NodeBs 110y and 110z may be femto NodeBs for the femto cells 102y and 102z, respectively. A NodeB 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 NodeB or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a NodeB). In the example shown in <FIG>, a relay station 110r may communicate with the NodeB 110a and a UE 120r in order to facilitate communication between the NodeB 110a and the UE 120r. A relay station may also be referred to as a relay NodeB. a relay, etc..

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

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

A network controller <NUM> may couple to a set of NodeBs and provide coordination and control for these NodeBs. The network controller <NUM> may communicate with the NodeBs <NUM> via a backhaul. The NodeBs <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 NodeBs, pico NodeBs, femto NodeBs, relays, etc. In <FIG>, a solid line with double arrows indicates desired transmissions between a UE and a serving NodeB, which is a NodeB 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 NodeB.

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. NR resource blocks may span <NUM> sub-carriers with a sub-carrier bandwidth of <NUM> over a <NUM> duration. Each radio frame may consist of <NUM> subframes and have a length of <NUM>. Consequently, each subframe may have a length of <NUM>. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include data in the indicated link direction (i.e., DL or UL) as well as both DL and UL control data. MIMO configurations in the DL may support up to <NUM> transmit antennas with multi--layer DL transmissions up to <NUM> streams and up to <NUM> streams per UE. Alternatively, NR may support a different air interface, other than an OFDM-based air interface.

<FIG> shows a down link (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> sub-frames with indices of <NUM> through <NUM>. Each sub-frame may include two slots. Each radio frame may thus include <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>) or <FIG> symbol periods for an extended cyclic prefix. The <NUM> symbol periods in each sub-frame may be assigned indices of <NUM> through <NUM>-<NUM>. Each resource block may cover N subcarriers (e.g., <NUM> subcarriers) in one slot.

In LTE, a NodeB may send a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) for each cell served by the NodeB. The primary and secondary synchronization signals may be sent in symbol periods <NUM> and <NUM>, respectively, in each of sub-frames <NUM> and <NUM> of each radio frame with the normal cyclic prefix, as shown in <FIG>. The synchronization signals may be used by UEs for cell detection and acquisition. The NodeB may send a Physical Broadcast Channel (PBCH) in symbol periods <NUM> to <NUM> in slot <NUM> of sub-frame <NUM>. The PBCH may carry certain system information.

The NodeB may send a Physical Control Format Indicator Channel (PCFICH) in only a portion of the first symbol period of each sub-frame, although depicted in the entire first symbol period in <FIG>. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to <NUM>, <NUM> or <NUM> and may change from sub-frame to sub-frame. M may also be equal to <NUM> for a small system bandwidth, e.g., with less than <NUM> resource blocks. In the example shown in <FIG>, M=<NUM>. The NodeB may send a Physical HARQ Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each sub-frame (M=<NUM> in <FIG>). The PHICH may carry information to support hybrid automatic retransmission (HARQ). The PDCCH may carry information on uplink and downlink resource allocation for UEs and power control information for uplink channels. Although not shown in the first symbol period in <FIG>, it is understood that the PDCCH and PHICH are also included in the first symbol period. Similarly, the PHICH and PDCCH are also both in the second and third symbol periods, although not shown that way in <FIG>. The NodeB may send a Physical Downlink Shared Channel (PDSCH) in the remaining symbol periods of each sub-frame. The PDSCH may carry data for UEs scheduled for data transmission on the downlink. The various signals and channels in LTE are described in <NPL>," which is publicly available.

The NodeB may send the PSS, SSS and PBCH in the center <NUM> of the system bandwidth used by the NodeB. The NodeB may send the PCFICH and PHICH across the entire system bandwidth in each symbol period in which these channels are sent. The NodeB may send the PDCCH to groups of UEs in certain portions of the system bandwidth. The NodeB may send the PDSCH to specific UEs in specific portions of the system bandwidth. The NodeB may send the PSS, SSS, PBCH, PCFICH and PHICH in a broadcast manner to all UEs, may send the PDCCH in a unicast manner to specific UEs, and may also send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value. Resource elements not used for a reference signal in each symbol period may be arranged into resource element groups (REGs). Each REG may include four resource elements in one symbol period. The PCFICH may occupy four REGs, which may be spaced approximately equally across frequency, in symbol period <NUM>. The PHICH may occupy three REGs, which may be spread across frequency, in one or more configurable symbol periods. For example, the three REGs for the PHICH may all belong in symbol period <NUM> or may be spread in symbol periods <NUM>, <NUM> and <NUM>. The PDCCH may occupy <NUM>, <NUM>, <NUM> or <NUM> REGs, which may be selected from the available REGs, in the first M symbol periods. Only certain combinations of REGs may be allowed for the PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. The UE may search different combinations of REGs for the PDCCH. The number of combinations to search is typically less than the number of allowed combinations for the PDCCH. A NodeB may send the PDCCH to the UE in any of the combinations that the UE will search.

A UE may be within the coverage of multiple NodeBs. One of these NodeBs may be selected to serve the UE. The serving NodeB 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 in the control section to transmit control information to a NodeB. The UE may also be assigned resource blocks 320a, 320b in the data section to transmit data to the NodeB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. 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 span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) <NUM>. The PRACH <NUM> carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (<NUM>) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (<NUM>).

<FIG> illustrates example components of the NodeB (e.g., TRP) <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. One or more components of the NodeB <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>.

For a restricted association scenario, the NodeB <NUM> may be the macro NodeB 110c in <FIG>, and the UE <NUM> may be the UE 120y. The NodeB <NUM> may also be a NodeB of some other type. The NodeB <NUM> may be equipped with antennas 434a through 434t, and the UE <NUM> may be equipped with antennas 452a through 452r.

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 NodeB 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 NodeB 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 NodeB 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 NodeBs. 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 NodeB 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 NodeB and the UE.

<FIG> shows two exemplary subframe formats <NUM> and <NUM> for the downlink with the normal cyclic prefix. The available time frequency resources for the downlink may be partitioned into resource blocks. Each resource block may cover <NUM> subcarriers in one slot and may include a number of resource elements. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value.

Subframe format <NUM> may be used for a NodeB equipped with two antennas. A CRS may be transmitted from antennas <NUM> and <NUM> in symbol periods <NUM>, <NUM>, <NUM> and <NUM>. A reference signal is a signal that is known a priori by a transmitter and a receiver and may also be referred to as a pilot. A CRS is a reference signal that is specific for a cell, e.g., generated based on a cell identity (ID). In <FIG>, for a given resource element with label Ra, a modulation symbol may be transmitted on that resource element from antenna a, and no modulation symbols may be transmitted on that resource element from other antennas. Subframe format <NUM> may be used for a NodeB equipped with four antennas. A CRS may be transmitted from antennas <NUM> and <NUM> in symbol periods <NUM>, <NUM>, <NUM> and <NUM> and from antennas <NUM> and <NUM> in symbol periods <NUM> and <NUM>. For both subframe formats <NUM> and <NUM>, a CRS may be transmitted on evenly spaced subcarriers, which may be determined based on cell ID. Different NodeBs may transmit their CRSs on the same or different subcarriers, depending on their cell IDs. For both subframe formats <NUM> and <NUM>, resource elements not used for the CRS may be used to transmit data (e.g., traffic data, control data, and/or other data).

The PSS, SSS, CRS and PBCH in LTE are described in <NPL>," which is publicly available.

An interlace structure may be used for each of the downlink and uplink for FDD in LTE. For example, Q interlaces with indices of <NUM> through Q - <NUM> may be defined, where Q may be equal to <NUM>, <NUM>, <NUM>, <NUM>, or some other value. Each interlace may include subframes that are spaced apart by Q frames. In particular, interlace q may include subframes q, q + Q , q + 2Q , etc., where q ∈ { <NUM>,. , Q - <NUM> }.

The wireless network may support hybrid automatic retransmission (HARQ) for data transmission on the downlink and uplink. For HARQ, a transmitter (e.g., a NodeB) may send one or more transmissions of a packet until the packet is decoded correctly by a receiver (e.g., a UE) or some other termination condition is encountered. For synchronous HARQ, all transmissions of the packet may be sent in subframes of a single interlace. For asynchronous HARQ, each transmission of the packet may be sent in any subframe.

A UE may be located within the coverage area of multiple NodeBs. One of these NodeBs may be selected to serve the UE. The serving NodeB may be selected based on various criteria such as received signal strength, received signal quality, pathloss, etc. Received signal quality may be quantified by a signal-to-noise-and-interference ratio (SINR), or a reference signal received quality (RSRQ), or some other metric. The UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering NodeBs.

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) techniques targeting wide bandwidth (e.g. <NUM> beyond) communications, millimeter wave (mmW) techniques targeting high carrier frequency (e.g. <NUM>) communications, massive MTC (mMTC) techniques targeting communications with non-backward compatible MTC devices, and mission critical techniques targeting ultra reliable low latency communications (URLLC).

An NR cell may refer to a cell operating according in an NR network. A NR NodeB (e.g., NodeB <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 a backhaul interface to the RAN core network (RAN-CN) and terminates backhaul interfaces to neighboring 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., a Global TRP identifier (TRP ID)), may include PDCP, RLC, and/or MAC functions, may comprise one or more antenna ports, and may be configured to individually (dynamic selection) or jointly (joint transmission) serve traffic to a UE.

According to aspects of the present disclosure, techniques are provided for dynamic multi-beam transmission and reception in NR multiple-input multiple-output wireless communication systems. The disclosed techniques relate to techniques for UEs to assist in selecting beams and antenna ports for transmissions to the UEs and techniques for reporting channel state information (CSI) based on beams and antenna ports selected for transmissions.

In NR communications systems, a UE may be served by one or more TRPs using single or multiple beams, as depicted in <FIG> shows an exemplary wireless communications system <NUM> in which a UE <NUM> is being served by a single TRP <NUM> using two beams <NUM>, <NUM>. <FIG> shows an exemplary wireless communications system <NUM> in which a UE <NUM> is being served by a TRP <NUM> using two beams <NUM>, <NUM> and another TRP <NUM> (e.g., using joint transmission) using a single beam <NUM>.

According to aspects of the present disclosure, a beam may be associated with one or more (beamformed) antenna ports, and an antenna port may be associated with a reference signal (RS). As used herein, a RS resource refers to a set of RSs and thus may be associated with a set of antenna ports and with a set of beams.

<FIG> show exemplary associations of beams with reference signal resources and antenna ports. In <FIG>, each of four beams <NUM>, <NUM>, <NUM>, <NUM> transmitted from TRP <NUM> is associated with two antenna ports. The four beams are also each associated with one RS resource. 8B, each of four beams <NUM>, <NUM>, <NUM>, <NUM> transmitted from TRP <NUM> is associated with four antenna ports. The four beams are also each associated with three RS resources.

In NR wireless communication systems, beam based transmissions may be used, wherein one or more layers of data are delivered to a UE using one or more antenna ports from a single or multiple TRPs. A layer(s) to port mapping may or may not be transparent to a UE receiving a transmission. That is, layers of a transmission to the UE may be mapped to antenna ports, and the UE may receive the transmission with or without having information regarding the mapping. By reporting CSI to a serving cell (e.g., to a TRP, to a NodeB), the UE may suggest use of a subset of beams and/or ports out of those associated with configured RS resource(s), the number of layers (e.g., suggested by the reported RI included in the CSI), and the MCS of each layer (e.g., suggested by the reported CQI included in the CSI), assuming a certain precoding (i.e., mapping from layers to the suggested beams/ports). The precoding may be determined according open loop or closed loop MIMO techniques. In the case of closed-loop MIMO (CL-MIMO), the precoding assumption for RI and/or CQI is also indicated by the UE reporting a precoding matrix indicator (PMI), which may also indicate that the UE suggests beam cycling. In the case of open-loop MIMO (OL-MIMO), the precoding assumption may be fully predetermined (e.g., in a network specification). For example, a defined codebook may be used, where the precoders in the codebook are cycled through in a series of transmissions. Additionally or alternatively, the precoding may be partially indicated by UE reporting a PMI and partially predetermined.

Two issues that may be addressed are i) how to have a UE assist a TRP (e.g., a NodeB) in selecting a beam and port, and, once selected, ii) how to have the UE report CSI based on this selection. <FIG> illustrates an example communications system <NUM> performing operations to report and receive CSI feedback (CSF) based on multiple beamformed (BF) CSI-RSs as mentioned above, according to aspects of the present disclosure. The exemplary communications system <NUM> includes an eNB <NUM> (e.g., a TRP) and a UE <NUM>. In the exemplary communications system, the UE is configured (e.g., via RRC signaling and/or according to a communications standard) to detect and/or measure four BF CSI-RS resources (e.g., sets of time and frequency resources), although the UE may be configured to detect and/or measure one or more (i.e. K) BF CSI-RS resources to perform the described technique. Each BF CSI-RS resource could be associated with <NUM>, <NUM>, <NUM>, or <NUM> ports corresponding to a particular beam pattern. The beam pattern could be a common beam pattern for all ports or a different beam pattern for each port. At <NUM>, the eNB transmits four BF CSI-RSs using <NUM>, <NUM>, <NUM>, or <NUM> antenna ports. The UE measures all K resources (that is, the K CSI-RS on the resources) and selects a best one for which to report CQI, PMI, and/or RI, assuming a closed-loop MIMO (CL-MIMO) transmission. At <NUM>, the UE reports a wideband CSI-RS resource indicator (CRI) to the eNB indicating the CSI resource that the UE prefers and CSF, such as a CQI, PMI, and/or RI conditioned on the CSI-RS resource indicated by the CRI. At <NUM>, the eNB transmits a data transmission, such as a PDSCH, with transmission parameters determined based on the CSF and the CSI-RS resource indicated by the CRI. While the example describes an eNB, the disclosure is not so limited, and the techniques described may be used in a communications system with a NodeB and/or one or more TRPs.

According to aspects of the present disclosure, a technique using a hybrid of CLASS B CSI-RS that involves different types of beamformed CSI-RS being supported to reduce CSI measurement complexity is provided. In one example, a UE may be configured to detect and/or measure <NUM> sets of beamformed CSI-RS. The first set is cell specific, while the second set is UE specific. In the hybrid CSI-RS technique, K > <NUM> cell-specific beamformed CSI-RSs are transmitted by a TRP over a long duty-cycle for CSI-RS resource selection. Transmitting BF CSI-RSs over a long duty-cycle may allow the communications system to perform time division multiplexed (TDM) beam sweeping. A UE reports CRI of one or more preferred beams when the UE is configured to detect and/or measure multiple BF CSI-RS (i.e., K > <NUM>). An eNB uses the CRI(s) that the UE reports (i.e., CRI(s) indicating the preferred beam(s) of the UE) to determine a precoder to use in transmitting a UE-specific BF CSI-RS to the UE. When the eNB transmits the UE--specific BF CSI-RS, the eNB also configures the UE to detect one BF CSI-RS (i.e., K=<NUM>). When the UE is configured to detect one BF CSI-RS, the UE reports a short-term CSF including, for example, an RI, a PMI, and/or a CQI. The UE assumes the transmission is transmitted using CL-MIMO when transmitting the CSF. When the UE reports PMI, it assumes CL MIMO precoding.

<FIG> shows an exemplary wireless communications system <NUM> operating according to the hybrid CSI-RS technique described above. The exemplary wireless communications system includes a TRP <NUM> and a UE <NUM>, but the hybrid CSI-RS technique is suitable for use in communications systems including multiple TRPs, UEs, NodeBs, and/or eNodeBs. The BF CSI-RSs transmitted by the TRP over a long duty cycle are shown at <NUM> and numbered <NUM>-<NUM>. While <NUM> BF CSI-RSs are shown, the disclosed technique may be performed using more of fewer BF CSI-RSs. In the exemplary system, the UE begins being configured to detect and/or measure the three BF CSI-RSs (i.e., K=<NUM>), numbered <NUM>, <NUM>, and <NUM>. The UE transmits a CRI indicating the CSI-RS resources preferred by the UE. The eNB uses the CRI(s) reported over time by the UE to determine a precoder to use in transmitting a UE-specific BF CSI-RS to the UE. The eNB transmits the UE-specific BF CSI-RS <NUM> to the UE and configures the UE to detect one BF CSI-RS (i.e., K=<NUM>). The UE detects the UE-specific BF CSI-RS and transmits a PMI, an RI, and a CQI based on the UE-specific BF CSI-RS, assuming a CL-MIMO transmission.

In the exemplary techniques illustrated in <FIG> and <FIG>, a UE reports one or more CRIs for a best or preferred CSI-RS resource or set of CSI-RS resources to a BS (e.g., a TRP, a NodeB, an eNodeB). The UE determines the best or preferred CSI-RS resource(s) based on measurements of the BF CSI-RSs that the UE detects/and/or measures. For example, the UE may determine a best or preferred CSI-RS resource from the CSI-RSs that the UE detects and/or measures based on reference signal received power (RSRP), reference signal received quality (RSRQ), and/or signal-to-noise ratio measurements of each of the CSI-RSs.

The BF CSI-RS operation in LTE (described above with reference to <FIG>) can be extended to NR, but limits dynamic beam selection for at least the following reasons. <NUM>) As the CRI reporting is wideband-wise rather than subband-wise, CRI based dynamic beam selection can be supported in the time domain, but not in the frequency domain. <NUM>) For OL-MIMO, a single beam transmission over the entire scheduled bandwidth may lose some frequency/spatial diversity, and subband-wise beam cycling is preferred. <NUM>) When space frequency block coding (SFBC) is used for transmit diversity, it is also preferable to associate different layers to different beams for increased diversity, but the BF CSI-RS technique in LTE does not allow this. <NUM>) Dynamic switching between CL-MIMO and OL-MIMO is not supported in the LTE BF CSI-RS technique, and this dynamic switching is expected to provide sizeable gains in some cases.

According to aspects of the present disclosure, for multiple beam transmission in NR, dynamic beam switching across spatial layers and (a set of) resource blocks can be supported. That is, different layers can be associated with different beams and different resource blocks can also be associated with different beams.

According to aspects of the present disclosure, for multiple beam transmission in NR, the beam selection can be transparent or non-transparent to a UE, based on whether multiple beams are from a single or multiple TRPs. That is, the beam selection can be transparent to a UE, if multiple beams are from the same TRP, or non-transparent if multiple beams are from different TRPs.

According to aspects of the present disclosure, for multiple beam transmission in NR, a UE may assume a reference transmission scheme for reporting CSI where there is dynamic beam switching across spatial layers and resource blocks.

According to aspects of the present disclosure, both UEs and BSs (e.g., TRPs, NodeBs, eNodeBs) may support both closed-loop and open-loop MIMO for multiple beam transmission in NR. That is, a BS may transmit signals on multiple beams using OL-MIMO, CL-MIMO, and/or both simultaneously (e.g., OL-MIMO to a first UE and CL-MIMO to a second UE), and UEs may receive and decode the transmissions on one or more of the beams that were sent using OL-MIMO and/or CL-MIMO. In addition, BSs may dynamically switch between CL-MIMO and OL-MIMO and vice-versa while transmitting to a UE without transmitting an indication of the switching, and the UE may receive and decode the transmissions.

According to aspects of the present disclosure, both UEs and BSs (e.g., TRPs, NodeBs, eNodeBs) may support dynamic beam switching across both spatial layers and resource blocks for multiple beam transmission in NR. That is, a BS may transmit different layers of a MIMO transmission using different beams and UEs may receive and decode the different layers of the transmission. Additionally or alternatively, a BS may transmit a signal using different beams on different resource blocks, and a UE may receive and decode the signal.

<FIG> is a schematic representation <NUM> of an exemplary transmit chain that may be a component in a TRP and may transmit according to timelines <NUM> and <NUM>, in accordance with aspects of the present disclosure. In the exemplary transmit chain, one or more codewords are obtained (e.g., from controller/processor <NUM> shown in <FIG>) and mapped to layers by a layer mapping component <NUM>. The layer mapping component sends the streams of the layers to combiners <NUM>, <NUM>, which each adds UE-specific reference signals (UE-RS) to the corresponding stream and assigns the corresponding stream to a port. The streams are then mapped to corresponding beams by a beam mapping component <NUM>. The streams are then mapped to transmission resources (e.g., time and frequency resources), by, for example, a TX/MIMO processor <NUM>, as shown in <FIG>. As illustrated in exemplary transmit timeline <NUM>, the streams can be mapped such that beam switching occurs across RBs, but not across spatial layers. That is, the beam used for the transmission switches from RB to RB, but both layer <NUM> (e.g., the layer associated with the UE-RS on port <NUM>) and layer <NUM> (e.g., the layer associated with the UE-RS on port <NUM>) use the same beam in each RB. Additionally or alternatively, the streams can be mapped such that beam switching occurs across spatial layers and RBs, as shown in the exemplary transmit timeline <NUM>. That is, layer <NUM> is switches from beam <NUM> to beam <NUM> in alternating RBs, and layer <NUM> also switches from beam <NUM> to beam <NUM> in alternating RBs, but is always transmitted using a different beam than the beam used for layer <NUM>.

According to aspects of the present disclosure, for beam based transmissions, antenna ports used for data transmission may be associated with a single TRP or multiple geographically separated TRPs. For transmissions from a single TRP, the data layer to antenna port mapping can be transparent to a receiving UE. That is, when a UE is receiving a MIMO transmission from a single TRP, the TRP can map the various layers of the MIMO transmission to various antenna ports and the UE can receive and decode the layers using parameters for the various beams used by the TRP for transmitting the MIMO transmission. For transmissions from multiple TRPs, intra-TRP layer-to-port mapping can be transparent to a receiving UE, similar to the case for transmissions from a single TRP. However, inter-TRP layer-to-port mapping is not transparent to a receiving UE. That is, the UE must receive and decode the various layers based on the mappings of layers to antenna ports and antenna ports to TRPs, as the UE must use the beam parameters corresponding to each TRP for receiving and decoding layers transmitted by that TRP.

According to aspects of the present disclosure, CSI reporting for dynamic beam switching may include a UE reporting a common RI and independent CQI and/or PMI for various beams. This technique may be used with both CL-MIMO transmissions and OL-MIMO transmissions.

According to aspects of the present disclosure, a UE may report CSI periodically or aperiodically. Additionally or alternatively, a UE may report each of RI, CQI, and PMI for various beams periodically or aperiodically. For example, a UE may be configured to report and may report: CQI periodically for all beams; RI and PMI periodically for a particular beam; and RI and PMI for other beams aperiodically (e.g., in response to a trigger from a BS).

According to aspects of the present disclosure, a UE may be configured (e.g., by a TRP, a NodeB, or an eNodeB) with K > <NUM> beamformed CSI-RS resources for CSI reporting for supporting dynamic beam switching. The K resources may be associated with different TRPs. The UE reports K CQIs and/or PMIs, each corresponding to one BF CSI-RS resource. For a given BF CSI-RS resource, the UE determines the CQI and/or PMI assuming either a CL-MIMO or OL-MIMO transmission using the ports associated with the BF CSI-RS resource.

As used herein, "assuming a transmission" means obtaining, via a receiver, radio waves from a set of time and frequency resources and treating the radio waves as a signal (e.g., by attempting decoding) transmitted by another device. Similarly, an assumed transmission is the signal obtained from the obtained radio waves.

<FIG> shows example operations <NUM> for reporting CSI for dynamic beam switching, in accordance with aspects of the present disclosure. Operations <NUM> may be performed by a UE, such as UE <NUM> shown in <FIG>, for example.

Operations <NUM> begin at <NUM> with receiving a plurality of channel state information reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the CSI-RSs and a set of antenna ports used in transmitting the corresponding CSI-RSs.

At <NUM>, operations <NUM> continue with assuming a plurality of first transmissions on a plurality of time-frequency resource units, each first transmission comprising a plurality of layers and using a plurality of the antenna ports associated with one of the plurality of CSI-RS resources, wherein different subsets of the antenna ports may be used for different time-frequency resource units in one transmission. Examples of time-frequency resource units include resource blocks and resource elements, discussed above with reference to <FIG>.

Operations <NUM> continue at <NUM> with determining a common rank for the assumed plurality of first transmissions and a plurality of first channel quality metrics, wherein each first channel quality metric is based on a corresponding first transmission.

At <NUM>, operations <NUM> conclude with transmitting a rank indicator (RI), indicating the determined common rank, and a plurality of first channel quality indicators (CQIs), each first CQI indicating one of the plurality of first channel quality metrics.

According to aspects of the present disclosure, a UE may report a best (e.g., determined based on RSRP, RSRQ, and/or SNR, as mentioned above) set of CRIs and an aggregated RI and/or CQI (for OL-MIMO) when reporting CSI for dynamic beam switching.

According to aspects of the present disclosure, a UE can be configured with K > <NUM> beamformed CSI-RS resources for CSI reporting for supporting dynamic beam switching. The K resources may be associated with different TRPs. The UE may report a set of L CRIs, L ≤ K, to indicate that the beams associated with the corresponding resources are preferred by the UE for dynamic beam switching. The UE may obtain the value of L, for example, based on a configuration obtained by the UE from a BS and/or based on an indication (e.g., a signal) received from a BS. The UE may also report a single aggregated RI and/or CQI, assuming an OL-MIMO transmission (e.g., using beam and/or port cycling, as described above with reference to <FIG>) using the ports associated with the L selected resources.

According to aspects of the present disclosure, a UE can be configured to report, and may report, CSI for beams periodically, aperiodically, or a combination thereof. For example, a UE may be configured to report CSI for a first beam periodically, and to report CSI for other beams aperiodically (e.g., in response to a trigger). In the example, the UE may report CSI for the first beam periodically, and report CSI for a second beam in response to a request from a BS to report CSI for the second beam.

Operations <NUM> begin at <NUM> with receiving a plurality of channel state information reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the CSI-RSs and a set of antenna ports used in transmitting the corresponding set of CSI-RSs.

At <NUM>, operations <NUM> continue with determining, based on a plurality of channel quality metrics corresponding to the plurality of CSI-RS resources, a subset of the CSI-RS resources assuming a transmission on a plurality of time-frequency resource units using the antenna ports corresponding to the determined CSI-RS resources, wherein two different subsets of the antenna ports may be used for two different time-frequency resource units in the assumed transmission. The channel quality metrics may be, for example, a reference signal received power (RSRP), a reference signal received quality (RSRQ), and/or a signal-to-noise ratio (SNR) measured and/or calculated by a UE receiving the CSI-RSs.

Operations <NUM> continue at <NUM> with determining a rank for the assumed transmission and a channel quality metric for the assumed transmission, based on the assumed transmission using the determined rank.

At <NUM>, operations <NUM> conclude with transmitting a plurality of CSI resource indicators (CRIs) indicating the determined CSI-RS resources, a rank indicator (RI) indicating the determined rank, and a channel quality indicator (CQI) indicating the channel quality metric corresponding to the assumed transmission.

According to aspects of the present disclosure, may include a UE may report a set of best reference CRI(s) and an aggregated RI/CQI (for OL-MIMO) when reporting CSI for dynamic beam switching.

According to aspects of the present disclosure, a UE can be configured with K > <NUM> beamformed CSI-RS resources for CSI reporting for supporting dynamic beam switching. The beamformed CSI-RS resources maybe associated with a same TRP or different TRPs. The UE may report a set of L CRIs, L ≤ K, to indicate that the beams associated with the corresponding resources shall be considered as a set of reference beams. The UE may derive a set of candidate beams for aggregated RI and/or CQI reporting, based on the set of reference beams under certain predetermined criteria. For example, all beams orthogonal to any beams in the reference set belong to the candidate beam set. The UE may report a single aggregated RI and/or CQI, assuming an OL-MIMO transmission (e.g., using beam and/or port cycling, as described above with reference to <FIG>) using the ports associated with the candidate beams.

Additionally or alternatively, a UE may be configured with K > <NUM> cell-specific BF CSI-RS resources and a UE-specific BF CSI-RS resource for CSI reporting for supporting dynamic beam switching. The UE may report a set of L CRIs, where L is less than or equal to K, to indicate that the beams associated with the corresponding cell-specific resources shall be considered as a set of reference beams. The UE may also report a single RI based on the reference beams. In different subframes, the UE-specific CSI-RS and/or transmissions to the UE can be beamformed using different beamformers derived from the reference beams. The UE may also report CQI and/or PMI based on a specific CSI-RS, assuming either an OL-MIMO or a CL-MIMO transmission scheme.

If the UE assumes an OL-MIMO transmission scheme, then the UE may report aggregated CQI for a given window of time. Aggregation windows can be either explicitly or implicitly indicated to the UE. That is, a BS (e.g., a TRP, a NodeB, an eNodeB) may determine a window of time for which a UE is to report aggregated CQI and signal the window or implicitly indicate the window to the UE. The UE may then report aggregated CQI for the indicated window of time.

<FIG> shows example operations <NUM> for wireless communications, in accordance with aspects of the present disclosure. Operations <NUM> may be performed by a UE, such as UE <NUM> shown in <FIG>, for example.

Operations <NUM> begin at <NUM> with receiving a plurality of cell-specific CSI-RSs, wherein a plurality of cell-specific CSI-RS resources each correspond to a set of the cell-specific CSI-RSs.

At <NUM>, operations <NUM> continue with receiving a set of UE-specific CSI-RSs, wherein a UE-specific CSI-RS resource corresponds to the UE-specific CSI-RSs.

Operations <NUM> continue at <NUM> with determining a plurality of best cell-specific CSI-RS resources assuming a first transmission on a plurality of time-frequency resource units using antenna ports associated with the determined cell-specific CSI-RS resources.

At <NUM>, operations <NUM> continue with determining a rank based on the assumed first transmission.

Operations <NUM> continue at <NUM> with determining a channel quality metric assuming a second transmission using the antenna ports associated with the determined CSI-RS resources and using the determined rank.

At <NUM>, operations <NUM> conclude with transmitting a plurality of CSI-RS resource indicators (CRIs) indicating the determined CSI-RS resources, a rank indicator (RI) indicating the determined rank, and a channel quality indicator (CQI) indicating the channel quality metric corresponding to the second assumed transmission.

According to aspects of the present disclosure, CSI reporting for dynamic beam switching may include two-level CRI reporting, with one level for CL-MIMO transmissions and another level for OL-MIMO transmissions.

According to aspects of the present disclosure, a UE may be configured (e.g., by a TRP, a NodeB, an eNodeB) with a plurality (i.e., K > <NUM>) of sets of beamformed CSI-RS resources for CSI reporting for supporting dynamic beam switching. The K sets of resources may be associated with different TRPs. The UE may report a first level wideband CRI to indicate that the beam(s) associated with the resource set corresponding to the CRI are preferred by the UE for dynamic beam switching. The UE may report a second level subband CRI to indicate a best beam (e.g., determined based on SNR, RSRP, and/or RSRQ of the preferred beams) in the selected resource set for the given subband.

For OL-MIMO transmissions, the UE may not report the second level subband CRI. The UE may report a single aggregated RI and/or CQI, with the UE calculating the RI and/or CQO assuming cycling of the beams associated with the selected resource set.

Operations <NUM> begin at <NUM>. with receiving a plurality of channel state information reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the CSI-RSs.

At <NUM>, operations <NUM> continue with determining a first set of the CSI-RS resources based on the plurality of CSI-RSs, assuming a transmission on a plurality of time-frequency resource units using antenna ports associated with the determined set of CSI-RS resources.

Operations <NUM> continue at <NUM> with determining a plurality of second CSI-RS resources based on the first set of CSI-RS resources, each for a time-frequency resource unit, assuming antenna ports associate with a second CSI-RS resource are used for the assumed transmission on the corresponding time-frequency resource unit.

At <NUM>, operations <NUM> continue with determining a rank for the assumed transmission.

Operations <NUM> continue at <NUM> with determining a channel quality metric based on the assumed transmission using the determined rank.

At <NUM>, operations <NUM> conclude with transmitting a first set of CSI-RS resource indicators (CRIs) indicating the determined first set of CSI-RS resources, a second set of CRIs indicating the determined second CSI-RS resources, each for the corresponding time-frequency resource unit, and a channel quality indicator (CQI) indicating the channel quality metric.

According to aspects of the present disclosure, the plurality of CSI-RS resources may not all be associated with a same transmit and receive point (TRP). That is, the plurality of CSI-RS resources may include CSI-RS resources associated with a plurality of TRPs, with one or more of the CSI-RS resources associated with each of the plurality of TRPs.

According to aspects of the present disclosure, a UE may report subbandspecific CRIs when reporting CSI reporting for dynamic beam switching for both CL-MIMO transmissions and OL-MIMO transmissions.

According to aspects of the present disclosure, a UE may be configured with a plurality (i.e., K > <NUM>) of beamformed CSI-RS resources for CSI reporting for supporting dynamic beam switching. The UE may report a best M CRIs, where the best CRI in the set of M CRIs is indicated, and the subband indices corresponding to each CRI. Additionally or alternatively, a UE may report a set of best CRIs, with each CRI corresponding to a respective set of subbands.

Operations <NUM> begin at <NUM> with receiving a plurality of channel state information reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the CSI-RSs.

At <NUM>, operations <NUM> continue with determining a plurality of best time-frequency resource units and a plurality of CSI-RS resources based on the CSI-RSs, each determined CSI-RS resource corresponding to a determined time-frequency resource unit assuming a transmission on each time-frequency resource unit using antenna ports associated with the corresponding determined CSI-RS resources.

Operations <NUM> continue at <NUM> with determining a rank for the assumed plurality of transmissions and a channel quality metric based on the assumed plurality of transmissions.

At <NUM>, operations <NUM> conclude with transmitting a plurality of pairs of CSI-RS resource indicators (CRIs) and indices of time-frequency resource units, wherein each pair indicates one of the determined best time-frequency resource units and the corresponding CSI-RS resource, a rank indicator (RI) indicating the determined rank, and a channel quality indicator (CQI) indicating the channel quality metric for the transmission.

According to aspects of the present disclosure, a UE may report both CL-MIMO and OL-MIMO based CSI feedback, in a same or separate reports. A TRP receiving the reports from the UE may choose the transmission scheme (i.e., CL-MIMO or OL-MIMO) dynamically, based on the reports from the UE.

According to aspects of the present disclosure, a UE may be triggered (i.e., aperiodic CSI (A-CSI)) to report CSI assuming an OL-MIMO-only transmission scheme, a CL-MIMO-only transmission scheme, or a transmission scheme using both OL-MIMO and CL-MIMO transmissions. That is, the CSI reporting for dynamic multibeam transmissions can be similar to current A-CSI reporting when used with carrier aggregation (CA) or coordinated multi-point transmission (CoMP), where one or more set of CSIs are configured on a UE for reporting by the UE. Each CSI measurement set can be associated with a specific transmission scheme, e.g., one for OL-MIMO, and one for CL-MIMO. The triggering of A-CSI reporting may include an indication of the CSI measurement set to support dynamic CSI reporting for different transmission schemes.

<FIG> illustrate exemplary operations for reporting CSI for dynamic beam switching, in accordance with aspects of the present disclosure described above.

<FIG> illustrates exemplary operations <NUM> for reporting CSI for beam switching, in accordance with aspects of the present disclosure. Operations <NUM> may be performed by a UE, such as UE <NUM> shown in <FIG>, for example.

Operations <NUM> begin at block <NUM>, where the UE receives a plurality of beamformed channel state information (CSI) reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the beamformed CSI-RSs. For example, the UE may receive the CSI-RSs from one or more TRPs, such as NodeB <NUM>, shown in <FIG>.

At block <NUM>, operations <NUM> continue with the UE reporting CSI, based on the plurality of beamformed CSI-RSs.

Operations <NUM> conclude at block <NUM> with the UE reporting a channel quality indicator (CQI) and a precoding matrix indicator (PMI) for each CSI-RS resource of the plurality of CSI-RS resources, wherein each of the CQIs and the PMIs are determined assuming a closed-loop multiple-input (CL-MIMO) or an open-loop multiple-input multiple-output (MIMO) transmission scheme and using antenna ports associated with the corresponding CSI-RS resource.

Operations <NUM> begin at block <NUM> with the UE receiving a plurality of beamformed channel state information (CSI) reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the beamformed CSI-RSs.

At block <NUM>, operations <NUM> continue with the UE selecting, based on a plurality of channel quality metrics corresponding to the plurality of CSI-RS resources, one or more best CSI-RS resources.

Operations <NUM> continue at block <NUM> with the UE reporting a set of CSI-RS resource indicators (CRIs), each CRI indicating one of the best CSI-RS resources, wherein beams associated with the CSI-RSs corresponding to the indicated CSI-RS resources may be considered for dynamic beam switching.

At block <NUM>, operations <NUM> conclude with the UE reporting at least one aggregated rank indicator (RI) or channel quality indicator (CQI) based on the CSI-RS resources corresponding to the set of CRIs, wherein an open-loop multiple-input multiple-output (OL-MIMO) transmission is assumed using antenna ports associated with the CSI-RS resources corresponding to the set of CRIs.

Operations <NUM> continue at block <NUM>, where the UE reports a set of CSI-RS resource indicators (CRIs), each CRI corresponding to a CSI-RS resource in the plurality of CSI-RS resources, wherein beams associated with the corresponding CSI-RS resources are considered as a set of reference beams.

At block <NUM>, operations <NUM> continue with the UE deriving a set of candidate beams for rank indicator (RI) or channel quality indicator (CQI) reporting based on the set of reference beams.

Operations <NUM> conclude at block <NUM> with the UE reporting at least one aggregated RI or CQI based on the set of candidate beams, wherein an open-loop multiple-input multiple-output (MIMO) transmission is assumed using antenna ports associated with the candidate beams.

Operations <NUM> continue at block <NUM> with the UE receiving a plurality of cell-specific beamformed CSI-RSs, wherein a plurality of cell-specific CSI-RS resources each correspond to a set of the cell-specific beamformed CSI-RSs, and a first UE-specific beamformed CSI-RS.

Operations <NUM> continue at block <NUM> with the UE reporting, in a subframe, a set of CSI-RS resource indicators (CRIs), each CRI corresponding to a cell-specific CSI-RS resource, wherein beams associated with the corresponding cell specific beamformed CSI-RS resources are considered as a set of reference beams.

At block <NUM>, operations <NUM> continue with the UE reporting, in the subframe, a rank indicator (RI) based on the reference beams.

Operations <NUM> continue at block <NUM> with the UE receiving one or more second UE-specific CSI-RSs in one or more other subframes, wherein the second UE-specific CSI-RSs are transmitted using at least one beamformer that is different from beamformers used to transmit cell specific CSI-RSs and is derived from the reference beams.

At block <NUM>, operations <NUM> conclude with the UE reporting a channel quality indicator (CQI) based on the first and second UE-specific CSI-RSs.

Operations <NUM> begin at block <NUM> with the UE receiving a plurality of beamformed channel state information (CSI) reference signals (CSI-RSs), wherein a plurality of CSI-RS resources each correspond to a set of the CSI-RSs.

Operations <NUM> conclude at block <NUM> with the UE reporting one or more first level wideband CSI-RS resource indicators (CRIs), each corresponding to a set of the CSI-RS resources, wherein beams associated with the set of resources are considered for dynamic beam switching.

Operations <NUM> continue at block <NUM> with the UE reporting one or more first level wideband CSI-RS resource indicators (CRIs), each corresponding to a set of CSI-RS resources, wherein beams associated with each of the sets of CSI-RS resources are considered for dynamic beam switching.

At block <NUM>, operations <NUM> conclude with the UE reporting at least one best CRI.

As with other aspects of the present disclosure, the plurality of CSI-RS resources described with reference to <FIG> may not all be associated with a same transmit and receive point (TRP). That is, the plurality of CSI-RS resources may include CSI-RS resources associated with a plurality of TRPs, with one or more of the CSI-RS resources associated with each of the plurality of TRPs.

At block <NUM>, operations <NUM> continue with the UE reporting CSI, based on the plurality of beamformed CSI-RS resources.

Operations <NUM> continue at block <NUM> with the UE reporting a first level wideband CSI-RS resource indicator (CRI), corresponding to a set of the CSI-RS resources, wherein beams associated with each of the sets of CSI-RS resources are considered for dynamic beam switching.

At block <NUM>, operations <NUM> conclude with the UE reporting an aggregated rank indicator (RI) or channel quality indicator (CQI) based on the CSI-RS resources corresponding to the set of CRIs, wherein an open-loop multiple-input multiple-output (OL-MIMO) transmission is assumed.

Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. §<NUM>, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for.

For example, operations <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> illustrated in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, may correspond to means 1200A, 1300A, 1400A, 1500A, 1600A, 1700A, 1800A, 1900A, 2000A, 2100A, 2200A, and 2300A illustrated in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>.

The processor may be implemented with one or more general-purpose and/or specialpurpose processors.

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 for wireless communications, performed by an apparatus, comprising:
receiving (<NUM>) a plurality of channel state information reference signals, CSI-RSs, wherein a plurality of CSI-RS resources each correspond to a set of the CSI-RSs and a set of antenna ports used in transmitting the corresponding set of CSI-RSs;
assuming (<NUM>) a plurality of first transmissions on a plurality of time-frequency resource units, each first transmission comprising a plurality of layers and using a plurality of the antenna ports associated with one of the plurality of CSI-RS resources, wherein different subsets of the antenna ports are used for different time-frequency resource units in one transmission;
determining (<NUM>) a common rank for the assumed plurality of first transmissions and a plurality of first channel quality metrics, wherein each first channel quality metric is based on a corresponding first transmission;
determining a plurality of first channel quality indicators, CQIs, each first CQI indicating one of the plurality of first channel quality metrics; and
transmitting (<NUM>) a best set of common rank and of the plurality of first CQIs.