JP2019083543A - Periodic and Aperiodic Channel State Information (CSI) Reporting for MIMO - Google Patents

Abstract

To provide techniques for performing periodic and aperiodic CSI reporting for MIMO operations.SOLUTION: An embodiment includes: configuring user equipment (UE) that is capable of MIMO with different parameters for periodic and aperiodic channel state information (CSI) reporting, where the different parameters indicate at least one of what resources to measure and what information to report 1602; and receiving periodic and aperiodic CSI reporting from the UE according to the configuration 1604.SELECTED DRAWING: Figure 16

Description

  [0001] Certain aspects of the present disclosure generally relate to wireless communications, and more particularly, multiple-input multiple-output (MIMO) channel state information (CSI) for periodic and aperiodic reporting. It relates to techniques for constructing feedback.

  Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple access systems capable of supporting communication with multiple users by sharing available system resources (eg, bandwidth and transmit power). Examples of such multiple access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Third Generation Partnership Project (3GPP): There are 3rd Generation Partnership Project) Long Term Evolution (LTE (R): Long Term Evolution) / LTE advanced systems and orthogonal frequency division multiple access (OFDMA) systems.

  Generally, a wireless multiple access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations by transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-single-out, or a multiple-in-multiple-out (MIMO) system.

  [0004] Certain aspects of the present disclosure are for reporting multiple-input multiple-output (MIMO) CSI feedback based on different parameters for periodic and aperiodic channel state information (CSI) reporting. Provide techniques.

  [0005] Certain aspects of the present disclosure provide a method for wireless communication by a base station (BS). The method generally comprises configuring a user equipment (UE) capable of MIMO with different parameters for periodic and aperiodic channel state information (CSI) reporting, and here the different parameters are what resources Indicating at least one of what to measure or what information to report, and receiving periodic and aperiodic CSI reports from the UE according to the configuration.

  [0006] Certain aspects of the present disclosure provide a method for wireless communication with a MIMO-capable user equipment (UE). The method generally comprises receiving from the base station a configuration of different parameters for periodic and aperiodic channel state information (CSI) reporting, and wherein here the different parameters should measure what resources or what information Indicating at least one of what should be reported, and measuring and reporting periodic and aperiodic CSI according to the configuration.

  Aspects of the present disclosure also include various apparatuses and program products for performing the operations according to the methods described above.

[0008] FIG. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with certain aspects of the present disclosure. [0009] FIG. 1 is a block diagram conceptually illustrating an example of a base station in communication with a user equipment (UE) in a wireless communication network, in accordance with certain aspects of the present disclosure. [0010] FIG. 1 is a block diagram conceptually illustrating an example of a frame structure in a wireless communication network, in accordance with certain aspects of the present disclosure. [0011] FIG. 1 illustrates an example of an antenna array that may be used for high dimensional multiple input multiple output (MIMO) communication, in accordance with certain aspects of the present disclosure. [0012] FIG. 7 illustrates an example antenna port structure, in accordance with certain aspects of the present disclosure. [0013] FIG. 6 illustrates an example of antenna port steering, in accordance with certain aspects of the present disclosure. [0014] FIG. 7 illustrates an example of antenna port steering for multiple elevation domain subsectors, in accordance with certain aspects of the present disclosure. [0015] FIG. 7 illustrates an example of separate information reporting configurations for periodic and aperiodic channel state information (CSI) reporting, in accordance with certain aspects of the present disclosure. [0016] FIG. 6 illustrates an example of separate resource configurations for periodically and aperiodically reporting channel state information (CSI), in accordance with certain aspects of the present disclosure. [0017] FIG. 7 illustrates another example of separate resource configurations for periodically and aperiodically reporting CSI, in accordance with certain aspects of the present disclosure. [0018] FIG. 10 illustrates an example of antenna selection options for periodically and aperiodically reporting CSI, in accordance with certain aspects of the present disclosure. [0019] FIG. 7 illustrates an example of a resource configuration for periodic CSI reporting, in accordance with certain aspects of the present disclosure. [0020] FIG. 10 illustrates an example structure definition for configuring resources for CSI reporting, in accordance with certain aspects of the present disclosure. FIG. 10 illustrates an example structure definition for configuring resources for CSI reporting, in accordance with certain aspects of the present disclosure. FIG. 10 illustrates an example structure definition for configuring resources for CSI reporting, in accordance with certain aspects of the present disclosure. [0021] FIG. 7 illustrates an example resource configuration for legacy and 3D-MIMO enabled UEs, in accordance with certain aspects of the present disclosure. [0022] FIG. 7 illustrates example operations that may be performed by a base station, in accordance with certain aspects of the present disclosure. [0023] FIG. 7 illustrates example operations that may be performed by a user equipment, in accordance with certain aspects of the present disclosure.

Detailed description

  [0024] Certain aspects of the present disclosure configure different parameters for periodic and non-periodic multiple-input multiple-output (MIMO) CSI feedback that may reduce feedback overhead for channel state information (CSI) reporting. Provide techniques for

  [0025] The techniques described herein may be used for various wireless communication networks, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, and so on. UTRA includes Wideband CDMA (WCDMA), Time Division Synchronous CDMA (TD-SCDMA), and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM (R)). The OFDMA network is based on Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Flash- A wireless technology such as OFDM® may be implemented. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) in both frequency division duplex (FDD) and time division duplex (TDD) use OFDMA on the downlink and SC on the uplink -A new release of UMTS that uses E-UTRA that utilizes FDMA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein may be used for the wireless networks and wireless technologies described above, as well as other wireless networks and wireless technologies. For clarity, certain aspects of the techniques are described below for LTE / LTE advanced, and LTE / LTE advanced terminology is used in much of the description below.

Exemplary wireless communication network
[0026] FIG. 1 shows a wireless communication network 100, which may be an LTE network or some other wireless network. Wireless network 100 may include several evolved Node Bs (eNBs) 110 and other network entities. An eNB is an entity that communicates with a user equipment (UE) and may also be called a base station, a Node B, an access point, and so on. Each eNB may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to the coverage area of an eNB and / or the eNB subsystem serving this coverage area, depending on the context in which the term is used.

  An eNB may provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell may cover a relatively large geographic area (eg, several kilometers in radius) and may allow unrestricted access by UEs subscribing to a service. Pico cells may cover relatively small geographic areas and may allow unrestricted access by UEs subscribing to a service. A femtocell may cover a relatively small geographic area (eg, home) and may have restricted access by UEs that have an association with the femtocell (eg, UEs in a closed subscriber group (CSG)) May be possible. An eNB for a macro cell may be referred to as a macro eNB. The eNB for a pico cell may be referred to as a pico eNB. An eNB for a femtocell may be referred to as a femto eNB or a home eNB (HeNB). In the example shown in FIG. 1, the eNB 110a may be a macro eNB for the macro cell 102a, the eNB 110b may be a pico eNB for the pico cell 102b, and the eNB 110 c may be a femto eNB for the femto cell 102c. An eNB may support one or more (eg, three) cells. The terms "eNB", "base station" and "cell" may be used interchangeably herein.

  Wireless network 100 may also include relay stations. A relay station is an entity that can receive transmissions of data from an upstream station (eg, an eNB or UE) and send transmissions of that data to a downstream station (eg, a UE or eNB). The relay station may also be a UE that can relay transmissions to other UEs. In the example shown in FIG. 1, relay station 110d may communicate with macro eNB 110a and UE 120d to facilitate communication between eNB 110a and UE 120d. A relay station may also be referred to as a relay eNB, a relay base station, a relay, and so on.

  The wireless network 100 may be a heterogeneous network including various types of eNBs, eg, macro eNBs, pico eNBs, femto eNBs, relay eNBs, and so on. These different types of eNBs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless network 100. For example, macro eNBs may have high transmit power levels (e.g., 5-40 watts) while pico eNBs, femto eNBs, and relay eNBs have lower transmit power levels (e.g., 0.1-2 watts) It can have

  Network controller 130 may couple to a set of eNBs and may coordinate and control for these eNBs. Network controller 130 may communicate with the eNBs via a backhaul. The eNBs may also communicate with one another directly or indirectly, eg, via a wireless backhaul or a wireline backhaul.

  [0031] The UEs 120 may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, and so on. UEs include cellular phones, personal digital assistants (PDAs), wireless modems, wireless communication devices, handheld devices, laptop computers, cordless phones, wireless local loop (WLL) stations, tablets, smartphones, netbooks, smart books, etc. obtain.

  [0032] FIG. 2 shows a block diagram of a design of a base station / eNB 110, which may be one of the base stations / eNBs of FIG. 1 and a UE 120, which may be one of the UEs of FIG. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, generally T ≧ 1 and R ≧ 1.

  [0033] At base station 110, a transmit processor 220 receives data from data source 212 for one or more UEs, and one or more modulations for each UE based on CQIs received from the UEs and Select a coding scheme (MCS), process (eg, encode and modulate) data for each UE based on the MCS (s) selected for that UE, and for all UEs Can give the data symbol of Transmit processor 220 may also process system information and control information (eg, CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols. Processor 220 may also generate reference symbols for reference signals (eg, CRS) and synchronization signals (eg, PSS and SSS). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may apply PMI (Precoding Matrix Indicator) feedback from the UE, if applicable, for the data symbols and for the control symbols. Then, spatial processing (eg, precoding) may be performed on overhead symbols and / or on reference symbols, and T output symbol streams may be provided to T modulators (MOD) 232a through 232t. . Each modulator 232 may process a respective output symbol stream (eg, for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (eg, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

  [0034] At UE 120, antennas 252a through 252r may receive downlink signals from base station 110 and / or other base stations, and may provide received signals to demodulators (DEMOD) 254a through 254r, respectively. Each demodulator 254 may condition (eg, filter, amplify, down convert, and digitize) its received signal to obtain input samples. Each demodulator 254 may further process input samples (eg, for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 258 processes (eg, demodulates and decodes) the detected symbols and provides decoded data for UE 120 to data sink 260 and provides decoded control signals and system information to controller / processor 280. obtain. The channel processor may determine RSRP, RSSI, RSRQ, CQI, etc.

  [0035] On the uplink, at UE 120, transmit processor 264 transmits data from data source 262 and control information from controller / processor 280 (eg, for reports comprising RSRP, RSSI, RSRQ, CQI, etc.) And can be processed. Processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 are precoded by TX MIMO processor 266 if applicable, further processed by modulators 254 a-254 r (eg, for SC-FDM, OFDM, etc.) and transmitted to base station 110 It can be done. At base station 110, uplink signals from UE 120 and other UEs are received by antenna 234, processed by demodulator 232, detected by MIMO detector 236 if applicable, and sent by UE 120 Further processing may be performed by the receive processor 238 to obtain the received data and control information. Processor 238 may provide the decoded data to data sink 239 and the decoded control information to controller / processor 240. Base station 110 may include a communication unit 244 and may communicate with network controller 130 via communication unit 244. Network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

  Controllers / processors 240 and 280 may direct the operation at base station 110 and UE 120, respectively. Processor 240 and / or other processors and modules at base station 110 and / or processor 280 and / or other processors and modules at UE 120 may perform or direct processes for the techniques described herein. Memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively. Scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

  [0037] As described in further detail below, when transmitting data to UE 120, base station 110 determines a bundling size based at least in part on the data allocation size, and the determined bundling size The resource blocks in each bundle may be precoded using a common precoding matrix. That is, the data in the resource block and / or the reference signal such as UE-RS are precoded using the same precoder. The power levels used for UE-RS in each RB of the bundled RBs may also be the same.

  UE 120 may be configured to perform complementary processing to decode data transmitted from base station 110. For example, UE 120 may determine a bundling size based on a data allocation size of received data transmitted from a base station in a bundle of consecutive resource blocks (RBs), and here, in resource blocks in each bundle. Based on the determined bundling size at which at least one reference signal is precoded using a common precoding matrix, and one or more reference signals (RS) transmitted from the base station Estimating at least one precoded channel and decoding the received bundle using the estimated precoded channel may be performed.

  [0039] FIG. 3 shows an exemplary frame structure 300 for FDD in LTE. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be partitioned into 10 subframes with indices 0-9. Each subframe may include two slots. Thus, each radio frame may include twenty slots with indices of 0-19. Each slot may include L symbol periods, eg, seven symbol periods for a normal cyclic prefix (as shown in FIG. 2), or six symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe may be assigned indices of 0 to 2L-1.

  [0040] In LTE, an eNB may send a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) on the downlink at a center 1.08 MHz of the system bandwidth for each cell supported by the eNB . The PSS and SSS may be transmitted in symbol periods 6 and 5 in subframes 0 and 5 of each radio frame with a normal cyclic prefix, respectively, as shown in FIG. The PSS and SSS may be used by the UE for cell search and acquisition. The eNB may send a cell-specific reference signal (CRS) over the system bandwidth for each cell supported by the eNB. The CRS may be transmitted during some symbol periods of each subframe and may be used by the UE to perform channel estimation, channel quality measurement, and / or other functions. The eNB may also transmit a physical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 of some radio frames. The PBCH may carry some system information. The eNB may send other system information such as a system information block (SIB) on physical downlink shared channel (PDSCH) in some subframes. The eNB may send control information / data on the physical downlink control channel (PDCCH) within the first B symbol periods of the subframe, where B is for each subframe It may be configurable. The eNB may transmit traffic data and / or other data on the PDSCH within the remaining symbol period of each subframe.

  [0041] In some systems, higher dimensional 3D MIMO (as well as "lower dimensional" 2D MIMO) systems have been considered to improve peak data rates. As an example, in a 2D antenna array system using 64 antennas, it is possible to deploy a grid of 8 × 8 antennas on a 2D plane, as shown in FIG. In this case, horizontal beamforming as well as vertical beamforming can be used to take advantage of beamforming / SDMA gain in both azimuth and elevation. Eight antennas at the eNB, deployed in the azimuth dimension only, enable SDMA or SU-MIMO in the horizontal direction. The further inclusion of antennas in elevation, however, also allows beamforming in the vertical plane (e.g. to support different floors in a high rise building).

Exemplary Periodic and Aperiodic Channel State Information Reporting
[0042] Certain aspects of the present disclosure provide a mechanism for using different parameters to configure periodic and aperiodic channel state information (CSI) reporting. This may allow for the reduction of feedback overhead for certain CSI reports.

  [0043] In some MIMO systems, including 3D MIMO systems, the number of antenna ports that can be considered may be constrained by the base station form factor. In developing a MIMO system, it is desirable to develop an antenna array capable of performing three-dimensional beamforming that can enable beamforming horizontally and vertically (ie in the azimuth and elevation dimensions) There is. For example, a 2D antenna array with more antenna ports may be designed to enable multi-user (MU) 3D MIMO.

  [0044] FIG. 5 shows an exemplary 2D antenna port structure that may be used for 3D MIMO beamforming. The 2D antenna port structure has eight antenna ports in the horizontal direction and four antenna ports in the vertical direction, for a total of 32 antenna ports. Each antenna port may be formed from a two-element vertical sub-array. Such sub-arrays can provide directional antenna gain in the elevation region.

  [0045] Figures 6A and 6B show an example of steering the antenna port to support elevation beamforming and 3D MIMO. In one example, as shown in FIG. 6A, the antenna ports can be steered in the same direction in elevation. This steering may allow for flexible elevation beamforming and 3D MIMO operation. In another example, as shown in FIG. 6B, elevation domain antennas can be steered in different directions. Steering the elevation area antenna in different directions may enable formation of multiple elevation area sub-sectors that may be adapted depending on the location of the user and traffic load.

  [0046] In a large antenna system, the number of channel responses that the terminal may need to estimate may be proportional to the number of transmit antenna ports. For implicit CSI feedback using channel quality indicator (CQI), precoding matrix indicator (PMI), or rank indicator (RI), the complexity involved in determining CSI reporting is , May increase exponentially with the number of antenna ports.

  [0047] The uplink resources required for CSI feedback may also scale with the number of antenna ports. However, CSI may be dropped if the amount of data exceeds the total number of multiplexed bits, as there may be a limit on the total number of multiplexing bits (eg, for periodic CSI feedback using PUCCH) . For example, for PUCCH format 3, 22 bits may be used to multiplex HARQ-ACK, scheduling request (SR) bits and channel state information; HARQ-ACK, SR, and CSI If the total number of bits for er exceeds 22 bits, some information may be dropped.

  However, in 3D-MIMO, not all antenna ports are visible to the UE, eg, all antenna ports have the same signal, depending on how the elevation antenna ports are mapped. It may not always be received by the UE at strength. However, reporting CSI for weak antenna ports can be pointless. Furthermore, for UEs in close proximity to the base station, beamforming with fewer antenna ports may achieve sufficient beamforming gain and capacity. These UEs may not need to provide CSI feedback for beamforming from all transmit antenna ports.

  Thus, for 3D-MIMO and multiple antenna ports, it is not always necessary for the 3D-MIMO capable UE (3D-MIMO capable UE) to report CSI for all antenna ports . For example, it may be desirable for the UE not to transmit periodic CSI feedback for all antenna ports using PUCCH.

  [0050] For example, when a large antenna array is used at the base station for 3D MIMO transmission, antenna selection may be applied for CSI measurement and feedback.

  In some cases, the BS may configure a CSI reporting mode to reduce CSI feedback overhead. For example, if the precoding matrix indicator (PMI) or rank indicator (RI) report (pmi-RI-report (pmi-RI-Report)) parameters are not configured for CSI reporting, then the UE has no precoding Assuming that only transmission diversity channel quality indicator (TX Div CQI) can be reported, the UE does not have to report PMI and RI. Alternatively, the UE may feed back CQI pre-coded to eNB and antenna port number dependent PMI and / or RI (antenna port number dependent PMI and / or RI). These reporting modes imply that transmit beamforming may not be based on feedback from the UE if the pmi-RI-reporting parameters are not configured for CSI reporting. Alternatively, fewer antenna ports may be configured for CSI feedback, which may limit the use of multiple antenna ports for 3D MIMO.

  [0052] To enable the use of multiple antenna ports in 3D MIMO, periodic and non-periodic CSI reports may be configured with different CSI parameters. Periodic CSI reporting may provide limited CSI for multiple antenna ports for 3D MIMO operation with some performance degradation, and non-periodic CSI reporting using PUSCH is for all configured antenna ports. Can give a perfect CSI for. Configuring periodic and aperiodic CSI reports with different parameters may reduce, for example, periodic CSI feedback overhead on the PUCCH. In some embodiments, the pmi-RI-reporting parameters for 3D MIMO capable UEs may be configured separately for periodic and aperiodic CSI reporting. For example, the pmi-RI-reporting parameter may be configured for aperiodic CSI reporting using PUSCH, but not for periodic CSI reporting using PUCCH. In some embodiments, 3D MIMO enabled UEs may be configured for periodic and non-periodic CSI reporting with different numbers of CSI-RS antenna ports. For example, antenna ports configured for periodic CSI reporting may be a subset of antenna ports configured for non-periodic CSI reporting. This subset may be configured by the eNB (eg, using higher layer signaling) or autonomously by the UE.

  Periodic CQI reporting using PUSCH may be configured with the same CSI reporting parameters used to configure aperiodic CSI reporting.

  [0054] FIG. 7 shows an example of separately configuring pmi-RI-reporting parameters for periodic and aperiodic CSI reporting. As shown, the UE may be configured with two pmi-RI-reporting parameters. An exemplary configuration may involve reporting only CQI for periodic CSI reporting, and reporting CQI, PMI, and RI for non-periodic reporting. Such a configuration may reduce the periodic CSI payload and may make periodic CSI reporting independent of the number of CSI-RS antenna ports.

  [0055] Configuring periodic and aperiodic CSI reports with different parameters may, in some embodiments, involve the use of different antenna selection for periodic and aperiodic CSI reports. Antenna selection for CSI feedback may be performed by either the base station or the UE. Regardless of whether antenna selection is performed by the base station or by the UE, the UE may be configured with a full set of CSI-RS antenna ports that may be used for aperiodic CSI reporting.

  [0056] In an aspect, antenna selection performed by a base station may involve the following procedure. The BS may send a CSI measurement configuration message to the UE. The CSI measurement message may comprise the time frequency resource configuration and the total number of CSI-RS antenna ports that may be used for aperiodic CSI measurement and reporting. Based on uplink received sounding reference signals (SRS), the BS can determine a subset of antenna ports for periodic CSI feedback for the UE. The UE may receive a message from the BS indicating a subset of antenna ports. For example, this message may comprise a bitmap of antenna ports, where a value of '1' represents an antenna port that may be used for periodic CSI feedback, and a value of '0' is for periodic CSI feedback. Represents an antenna port that may not be used for The UE may perform channel measurements for the subset of antenna ports. Channel measurements may be performed by assuming that downlink data may be transmitted from only a subset of antenna ports, and CSI reporting from antennas outside the subset (ie, ports not used for periodic CSI feedback) May be generated by treating the transmissions of T.sub.1 as interference to a subset of antenna ports. Based on the uplink measurements, the BS may update the subset of antenna ports selected for periodic CSI feedback.

  [0057] FIG. 8 shows an example of antenna selection performed by the BS to configure and execute periodic and aperiodic CSI reports by the UE. For periodic CSI reporting, a first UE may be configured to use a first set of antenna ports (e.g., antenna ports 0-15), and a second UE may be configured to receive a second set of antenna ports. It may be configured to use a set (e.g., antenna ports 16-31). The first UE and the second UE may feed back the periodic CSI for the selected antenna port. Based on CSI feedback and antenna port selection, the BS may perform user pairing and scheduling, and may configure beamforming vectors for the base station. For example, the BS may configure a beamforming vector for the first UE according to the following equation:

The beamforming vector for the second UE may be configured according to the following equation:

Where W ₁₁ and W ₂₂ comprise precoding vectors determined from periodic CSI reports from the first UE and the second UE, respectively. For example, for a set of 32 antenna ports, W ₁₁ and W ₂₂ may each comprise a 16 × 1 precoding vector.

  [0058] In an aspect, the UE may perform antenna selection for periodic and aperiodic CSI reporting. The UE receives CSI measurement configuration from the BS, which may indicate the total number of CSI-RS antenna ports and time frequency resource configuration. The UE may measure the received signal power for each antenna port and may select a set of antenna ports based on these measurements. For example, for periodic CSI reporting, the UE may select a set of antenna ports with relatively strong received power measurements. The UE may report the measured CSI for the selected antenna port, and may also report to the BS an indication of antenna port selection (eg, a bitmap such as those described above).

  [0059] FIG. 9 shows an example of antenna selection performed by the UE to configure and execute periodic and aperiodic CSI reports. Several UEs may be configured with the total number of antenna ports. For example, as shown, the BS may have a total of 32 antenna ports, for example, using multiple elevation subvectors. The first UE may determine that the first set of ports (eg, ports 0-7) have the strongest received signal power, and may select the first set of ports for periodic CSI reporting. The second UE determines that the second set of ports (eg, ports 16-19 and 28-31) have the strongest received signal power, and selects the second set of ports for periodic CSI reporting It can. The UE may measure the CSI of the selected antenna port, including CQI, PMI, and / or RI, and may report CSI and antenna port selection indication to the BS.

  [0060] Using a bitmap pattern for antenna port selection feedback can be costly because the bitmap pattern can involve the use of a large number of bits (eg, one bit for each antenna). It may be desirable to reduce the amount of resources used to signal antenna selection.

  Furthermore, the codebook associated with PMI may be determined by the array structure. For example, a discrete Fourier transform (DFT) based codebook may be used for closely spaced uniform linear array (ULA) structures.

  [0062] If any antenna selection may be used for periodic CSI reporting, multiple codebook sets may need to be defined for different array structures. Defining multiple codebook sets can increase complexity. It may be desirable to limit antenna port selection for periodic CSI reporting in order to minimize the increase in complexity.

  [0063] FIG. 10 illustrates an example of antenna selection options that may be used in a 16-port 2D uniform planar array (UPA). With the antenna selection option, the 16 port UPA may fall back to an 8 port ULA where a common codebook structure for the selected 8 ports may be defined. Furthermore, the UE need only provide feedback on periodic CSI port selection, which may comprise a smaller number of bits than the bitmap representing antenna selection. For example, for a 16 port antenna array and 4 port selection options, the port selection feedback may comprise 2 bits instead of 16 bits.

[0064] In one embodiment, periodic CSI reporting configuration may involve single frequency network (SFN) -like precoding similar to single frequency network (SFN). SFN-like precoding may involve splitting the configured CSI-RS antenna port into several antenna groups. For example, antenna ports may be divided into groups by 2D UPA columns or rows. Each of the antenna groups may employ the same precoding, and the UE may assume antenna groups by assuming that each antenna group uses the same precoding and selecting antenna groups based on the precoding. It is possible to choose. For example, UE k may report a common precoding matrix W _k for B antenna groups. Row of W _k may comprise L _k right singular vector corresponding to the composite channel L _k largest singular value of the (composite channel) (largest singular values ) the (right singular vectors).

In the above formula,

Represents the channel matrix of the b-th antenna group.

[0065] FIG. 11 shows an example of SFN-like precoding for periodic CSI reporting. Two groups of antenna ports are shown, however, it can be appreciated that the BS can constitute any number of groups of antenna ports. When the BS receives the feedback precoding matrix W _k , the BS may construct a transmit precoding vector W ^(K) for the antenna port. For example, the transmit precoding vector for the illustrated two group example may be represented according to the following equation:

The received signal may be represented according to the following equation:

  [0066] FIG. 12 illustrates an exemplary structure for configuring CSI-RS resources. In this example, up to eight non-zero power (NZP) CSI-RS antenna ports may be configured for each CSI-RS resource. The resourceConfig element may define resource elements in the frequency domain that may be used for CSI-RS transmission, and the subframeConfig element may define subframes in the time domain that may be used for CSI-RS. The antennaPortsCount element may be extended to support larger CSI-RS antenna port configurations. Extending the antennaPortsCount element may involve changing the resourceConfig element, which may be limited to a maximum of 8 port mappings to resource elements.

  [0067] A composite CSI-RS resource with multiple CSI-RS antenna ports may be constructed from multiple CSI-RS resources with less number of CSI-RS antenna ports. FIG. 13 shows an exemplary structure for configuring a larger number of CSI-RS ports. Multiple NZP-CSI-RS resources may be aggregated into the NZP-CSI-RS configuration. For example, as shown, two NZP-CSI-RS resources (eg, two sets of antennaPortsCount, resourceConfig, and subframeConfig elements) may be aggregated to support 16 CSI-RS port configuration. FIG. 14 shows another exemplary structure for configuring a larger number of CSI-RS ports. Multiple NZP-CSI-RS resources may be included in the CSI process.

  [0068] Increasing the size of the NZP-CSI-RS configuration is correct for PDSCH rate matching with legacy UEs (ie, non-3D-MIMO capable UEs). It can cause things not to be done. Data puncturing may not provide good downlink performance if the reference signal overhead per resource block is large. In some embodiments, providing successful PDCCH rate matching with legacy UEs may involve spreading the CSI-RS port in multiple subframes. Spreading the CSI-RS port across subframes may allow maintenance of a small reference signal overhead for each resource block. For example, spreading the CSI-RS port into multiple subframes provides acceptable performance impact on legacy UEs, with overhead per resource block, per subframe, from eight resource elements Can also be implemented to be smaller or equal. In some embodiments, the configuration of zero power (ZP) CSI-RS resources may include resources reserved for NZP-CSI-RS ports not configured for use by legacy UEs.

  [0069] FIG. 15 shows an exemplary NZP-CSI-RS configuration for a 16-port NZP-CSI-RS configuration. In subframe n, legacy UEs and 3D MIMO UEs can share the same NZP-CSI-RS resource. In subframe n + 1, the NZP-CSI-RS resource for 3D MIMO UE may overlap with the ZP-CSI-RS resource for legacy UE. Thus, legacy UEs can correctly perform PDSCH rate matching around the 16 port configuration for 3D MIMO UEs.

  [0070] FIG. 16 illustrates example operations 1600 that may be performed by a base station (eg, an eNodeB) to provide reduced overhead for CSI reporting, in accordance with aspects of the present disclosure. Act 1600 may start at 1602 and the BS configures a UE capable of 3D MIMO with different parameters for periodic and aperiodic CSI reporting, where different parameters should measure what resources Or indicate at least one of what information should be reported. At 1604, the BS receives periodic and aperiodic CSI reports from the UE according to the configuration.

  [0071] FIG. 17 illustrates example operations 1700 that may be performed by a user equipment to provide reduced overhead for CSI reporting, in accordance with aspects of the present disclosure. Act 1700 may begin at 1702 with the UE receiving from the BS configuration of different parameters for periodic and non-periodic CSI reporting, wherein different parameters report what resources to measure or what information Indicates at least one of what to do. At 1704, the UE measures and reports periodic and non-periodic CSI according to its configuration.

  Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description may be voltages, currents, electromagnetic waves, magnetic fields or particles, light fields or particles, or any of them. It may be represented by a combination.

  [0073] Further, those skilled in the art will appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or a combination of both Will be comprehended. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

  [0074] The various exemplary logic blocks, modules, and circuits described in connection with the disclosure herein may be general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) Or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. obtain.

  [0075] The steps of a method or algorithm described in connection with the disclosure herein may be implemented directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may be RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage known in the art. May reside in the media. An exemplary storage medium is coupled to the processor such that the processor can read information from, and / or write information to the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. In general, where there are operations shown in the figures, those operations may have means-plus-function components of corresponding counterparts with similar numbers.

  [0076] In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored on or read out of computer readable media as one or more instructions or code. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example and not limitation, such computer readable media may be RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage device, or any desired program in the form of instructions or data structures. The code means may be used to carry or store and may comprise any other medium which may be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Also, any connection is properly termed a computer-readable medium. For example, software transmits from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, wireless, and microwave When included, wireless technology such as coaxial cable, fiber optic cable, twisted pair, DSL, or infrared, wireless, and microwave are included in the definition of medium. As used herein, discs and discs are compact discs (CDs), laser discs (registered trademark) (discs), optical discs (discs), digital versatile discs (disc) (DVDs) B) a floppy disk (disk) and a blu-ray disk (disc), wherein the disk normally reproduces data magnetically and the disk is Optically reproduce the data with a laser. Combinations of the above should also be included within the scope of computer readable media.

  [0077] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0077] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The invention described in the claims at the beginning of the application of the present application is appended below.
[C1]
A method of wireless communication by a base station (BS), comprising
Configuring a user equipment (UE) capable of MIMO with different parameters for periodic and aperiodic channel state information (CSI) reporting, and here the different parameters should measure what resources or Indicates at least one of what information to report,
Receiving periodic and aperiodic CSI reports from the UE according to the configuration;
A method comprising.
[C2]
The method according to C1, wherein the UE is capable of 3D MIMO with 9 or more antenna ports.
[C3]
Said configuring
Configuring the UE to report a first set of information for periodic CSI reporting;
Configuring the UE to report a second set of information for aperiodic CSI reporting
The method according to C1, comprising
[C4]
Rather than the first set of information, the second set of information comprises precoding matrix indicator (PMI) and rank indication (RI) information.
The method described in C3.
[C5]
When the CSI is aperiodically reported using Physical Uplink Shared Channel (PUSCH), said second set of information comprises PMI and RI information;
When the CSI is periodically reported using a Physical Uplink Control Channel (PUCCH), the first set of information does not comprise PMI and RI information,
The method described in C4.
[C6]
Said configuring
Configuring the UE to measure and report CSI non-periodically for a first set of antenna ports;
Configuring the UE to periodically measure and report CSI for a second set of antenna ports
The method according to C1, comprising
[C7]
The method of C6, wherein the second set of antenna ports comprises a subset of the first set of antenna ports.
[C8]
The method of C6, further comprising: signaling an indication of the first set of antenna ports and the second set of antenna ports.
[C9]
The method of C6, further comprising determining different subsets of antenna ports based on received uplink reference signals for different UEs.
[C10]
The method of C6, further comprising: determining different subsets of antenna ports based on the indication of selected antenna ports received from the UEs for different UEs.
[C11]
The method of C10, wherein the indication is used to select one of a plurality of predefined antenna port selection options.
[C12]
A method of wireless communication by user equipment (UE) capable of MIMO, comprising:
Receiving from the base station a configuration of different parameters for periodic and aperiodic channel state information (CSI) reporting, wherein here the different parameters should measure what resources or what information to report Show at least one of them,
Measuring and reporting periodic and non-periodic CSI according to said configuration
A method comprising.
[C13]
The method according to Calim 12, wherein the UE is capable of 3D MIMO with 9 or more antenna ports.
[C14]
The different parameters are
With a first set of information for periodic CSI reporting,
With a second set of information for aperiodic CSI reporting
The method according to C12, comprising
[C15]
Rather than the first set of information, the second set of information comprises precoding matrix indicator (PMI) and rank indication (RI) information.
The method described in C14.
[C16]
When the CSI is aperiodically reported using Physical Uplink Shared Channel (PUSCH), said second set of information comprises PMI and RI information;
When the CSI is periodically reported using a Physical Uplink Control Channel (PUCCH), the first set of information does not comprise PMI and RI information,
The method described in C15.
[C17]
The different parameters are
A first set of antenna ports for measuring and reporting CSI non-periodically;
With a second set of antenna ports to periodically measure and report CSI
The method according to C12, comprising
[C18]
The method of C17, wherein the second set of antenna ports comprises a subset of the first set of antenna ports.
[C19]
The method of C17, further comprising receiving from the base station signaling indicating the first set of antenna ports and the second set of antenna ports.
[C20]
Receiving an initial configuration of available antenna ports;
Providing an indication of the selection of the subset of available antenna ports to the base station based on received signal measurements for the antenna ports;
The method of C17, further comprising:
[C21]
The indication is a bitmap indicating the selected antenna port, wherein the bitmap comprises a smaller number of bits than the number of available antenna ports, or a precoding matrix indicating the selected antenna port The method of C20, comprising at least one of: wherein the indication comprises an indication to select one of a plurality of predefined antenna port selection options.

Claims (21)

A method of wireless communication by a base station (BS), comprising
Configuring a user equipment (UE) capable of MIMO with different parameters for periodic and aperiodic channel state information (CSI) reporting, and here the different parameters should measure what resources or Indicates at least one of what information to report,
Receiving periodic and aperiodic CSI reports from the UE according to the configuration.   The method according to claim 1, wherein the UE is capable of 3D MIMO with 9 or more antenna ports. Said configuring
Configuring the UE to report a first set of information for periodic CSI reporting;
The method of claim 1, comprising configuring the UE to report a second set of information for aperiodic CSI reporting. Rather than the first set of information, the second set of information comprises precoding matrix indicator (PMI) and rank indication (RI) information.
The method of claim 3. When the CSI is aperiodically reported using Physical Uplink Shared Channel (PUSCH), said second set of information comprises PMI and RI information;
When the CSI is periodically reported using a Physical Uplink Control Channel (PUCCH), the first set of information does not comprise PMI and RI information,
5. The method of claim 4. Said configuring
Configuring the UE to measure and report CSI non-periodically for a first set of antenna ports;
The method of claim 1, comprising configuring the UE to periodically measure and report CSI for a second set of antenna ports.   7. The method of claim 6, wherein the second set of antenna ports comprises a subset of the first set of antenna ports.   7. The method of claim 6, further comprising: signaling an indication of the first set of antenna ports and the second set of antenna ports.   7. The method of claim 6, further comprising determining different subsets of antenna ports based on received uplink reference signals for different UEs.   7. The method of claim 6, further comprising determining different subsets of antenna ports based on an indication of selected antenna ports received from the UEs for different UEs.   11. The method of claim 10, wherein the indication is used to select one of a plurality of predefined antenna port selection options. A method of wireless communication by user equipment (UE) capable of MIMO, comprising:
Receiving from the base station a configuration of different parameters for periodic and aperiodic channel state information (CSI) reporting, wherein here the different parameters should measure what resources or what information to report Show at least one of them,
Measuring and reporting periodic and non-periodic CSI according to the configuration.   The method according to Calim 12, wherein the UE is capable of 3D MIMO with 9 or more antenna ports. The different parameters are
With a first set of information for periodic CSI reporting,
13. The method of claim 12, comprising: a second set of information for aperiodic CSI reporting. Rather than the first set of information, the second set of information comprises precoding matrix indicator (PMI) and rank indication (RI) information.
The method of claim 14. When the CSI is aperiodically reported using Physical Uplink Shared Channel (PUSCH), said second set of information comprises PMI and RI information;
When the CSI is periodically reported using a Physical Uplink Control Channel (PUCCH), the first set of information does not comprise PMI and RI information,
The method of claim 15. The different parameters are
A first set of antenna ports for measuring and reporting CSI non-periodically;
13. The method of claim 12, comprising: a second set of antenna ports for periodically measuring and reporting CSI.   The method of claim 17, wherein the second set of antenna ports comprises a subset of the first set of antenna ports.   18. The method of claim 17, further comprising receiving, from the base station, signaling indicative of the first set of antenna ports and the second set of antenna ports. Receiving an initial configuration of available antenna ports;
The method of claim 17, further comprising: providing an indication of selection of the subset of available antenna ports to the base station based on received signal measurements for the antenna ports.   The indication is a bitmap indicating the selected antenna port, wherein the bitmap comprises a smaller number of bits than the number of available antenna ports, or a precoding matrix indicating the selected antenna port 21. The method of claim 20, comprising at least one of: wherein the indication comprises an indication to select one of a plurality of predefined antenna port selection options.