CN114826444B - Method for measuring and reporting downlink channel state information and user equipment - Google Patents
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Abstract
A method and user equipment for downlink channel state information (DL CSI) measurement and reporting is presented in an FR1 Frequency Division Duplex (FDD) system. The CSI reference signal (CSI-RS) points to the primary spatial (SD, beam) and frequency (FD, delay) components in the propagation environment. With partial channel reciprocity, the angle and delay in the DL channel can be obtained by UL channel measurements. The UE only needs to measure and feed back DLCSI corresponding to the dominant angle and delay. The BS obtains a precoder in the antenna frequency domain using CSI feedback in the beam time delay domain. The BS transmits through a Physical Downlink Shared Channel (PDSCH) using a precoder. In one embodiment, the UE reconstructs the DL channel over multiple delays using DL channels estimated over several beamformed CSI-RSs and delay tap indices signaled from the network.
Description
Cross Reference to Related Applications
The subject matter of the present application is incorporated herein by reference IN accordance with 35 U.S. c. ≡119 claiming priority from the indian application entitled "Method for FR1 FDD CSI", application number IN202121002253, filed on 1 month 18 2021.
Technical Field
The disclosed embodiments relate generally to mobile communication networks and, more particularly, to a method for improving channel state information (channel state information, CSI) estimation performance in FR1 frequency division duplex (kequency division duplex, FDD) systems.
Background
The fifth generation new radio (Fifth generation new radio,5G NR) is an improved radio access technology (radio access technology, RAT) that provides higher data rates, higher reliability, lower latency, and improved system capacity. In an NR system, a terrestrial radio access network includes a plurality of Base Stations (BS), called next generation node BS (next generationNode-B, gNB), which communicate with a plurality of mobile stations (UE). The UE may communicate with the base station or the gNB via a Downlink (DL) and an Uplink (UL). DL refers to communication from a base station to a UE. UL refers to communication from a UE to a base station. The 5GNR standard is established by 3 GPP.
In a frequency division duplex (Frequency division duplex, FDD) system, downlink channel state information (channel state information, CSI) feedback overhead generally increases with the number of transmit antenna elements (SDs) and the channel bandwidth (FD). To mitigate overhead, there is a need for a downlink channel measurement and reporting method in which CSI reference signals (CSI reference signal, CSI-RS) can be directed to the primary SD and FD components in the propagation environment. In abstract terms, the SD basis vector represents the (arrival/departure) angle, while the FD basis vector represents the delay tap. Physically, the above procedure corresponds to beamforming CSI-RS into scatterers (modulators) in the environment, where the scatterers are associated with angles and delays. With partial channel reciprocity, the angle and delay in the DL channel can be obtained by UL channel measurements. Once completed, the UE only needs to measure and feedback the downlink CSI corresponding to the dominant angle and delay.
For good throughput performance, a large number of dominant angles and delays need to be acquired, which results in a large number of beamformed CSI-RS ports for channel estimation. The space domain resolution of the channel is increased by a large number of dominant angles, so that the MIMO performance is improved. The large amount of dominant time delay increases the frequency domain resolution of the channel, thereby improving the frequency domain resource allocation performance. However, a large number of beamformed CSI-RS ports may increase CSI-RS overhead. The new CSI mechanism needs to have good resolution in SD and FD while maintaining reasonable CSI-RS overhead and CSI feedback overhead.
Disclosure of Invention
A method of downlink channel state information (downlink channel state information, DL CSI) measurement and reporting is proposed in an FR1 (frequency range 1, as specified in 5G NR) FDD system. CSI-RS points to the primary spatial domain (SD/beam) and frequency domain (FD/delay) components in the propagation environment. With partial channel reciprocity, the angle and delay in the DL channel can be obtained by UL channel measurements. The UE only needs to measure and feedback DL CSI corresponding to the dominant angle and delay. The feedback is in the form of a precoder matrix (precoding matrix indicator (precoding matrix indicator, PMI)) in the beam delay domain. The BS reconstructs the precoder in the antenna frequency domain using CSI feedback in the beam-time delay domain. The BS uses this reconstructed precoder to transmit over the physical downlink shared channel (Physical downlink shared channel, PDSCH). To improve frequency domain resolution, the UE reconstructs the DL channel over multiple delays using the DL channel estimated on several beamformed CSI-RS ports and a delay tap index signaled from the network. Further, to reduce CSI-RS overhead, the UE measures and reports CSI (e.g., PMI, channel quality indicator (channel quality indicator, CQI)) for a subset of the signaling bandwidth of the DL channel.
In one embodiment, a UE transmits a sounding reference signal (sounding reference signal, SRS) to a Base Station (BS) over an UL channel in an FDD network. The UE receives CSI-RS through a DL channel. CSI-RS ports for CSI-RS transmission pass through precoding matrix W derived from SRS D Mapped to the corresponding BS transmit antenna. The UE receives one or more frequency domain base indexes from the BS. The UE estimates CSI of the DL channel using the received frequency domain base index information and the precoded CSI-RS. The UE reports the estimated CSI to the BS for subsequent DL transmissions. The estimated CSI includes Rank Indicator (RI), precoding matrix fingersIndicator (precoding matrix indicator, PMI) and channel quality indicator (channel quality indicator, CQI).
According to the method for measuring and reporting the downlink channel state information (DL CSI) and the user equipment, the CSI estimation and reporting mechanism with good resolution in SD and FD can be realized while reasonable CSI-RS overhead and CSI feedback overhead are maintained.
Other embodiments and advantages are described in the detailed description that follows. This summary is not intended to define the invention. The invention is defined by the claims.
Drawings
Fig. 1 illustrates a mobile communication network with CSI-RS beamforming for reduced overhead CSI acquisition and reporting in accordance with a novel aspect. A precoder for data transmission after CSI acquisition is completed according to one novel aspect is also shown.
Fig. 2 is a simplified block diagram of a base station and user equipment that perform some embodiments of the present invention.
Fig. 3 illustrates a sequence flow for the entire process of CSI acquisition and reporting in accordance with one novel aspect.
Fig. 4 illustrates an uplink channel estimate with dominant beam and time delay and a corresponding downlink estimate in the beam time delay domain in accordance with a novel aspect.
Fig. 5 illustrates a first embodiment of channel reconstruction using estimated channels on several beamformed CSI-RSs and signaled delay tap indices.
Fig. 6 illustrates a second embodiment of measuring and reporting a subset of channel state information (PMI, CQI) of a signaling bandwidth.
Fig. 7 is a flow chart of a method of CSI acquisition and reporting from the perspective of a UE in accordance with a novel aspect.
Detailed Description
Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.
Fig. 1 illustrates a mobile communication network with CSI-RS beamforming for CSI acquisition and reporting with reduced overhead in accordance with a novel aspect. The mobile communication network 100 is an OFDM network comprising a serving base station gNB 101, a first user equipment 102 (ue#1) and a second user equipment 103 (ue#2). In the 3gpp nr system based on the OFDMA downlink, radio resources are divided into subframes in the time domain, each subframe consisting of a plurality of OFDM symbols. Each OFDMA symbol is also composed of multiple OFDMA subcarriers in the frequency domain, depending on the system bandwidth. The basic unit of the Resource grid is called a Resource Element (RE), which spans OFDMA subcarriers on one OFDMA symbol. REs are grouped into Resource Blocks (RBs), where each RB consists of twelve consecutive subcarriers in one slot.
Several physical downlink channels and reference signals are defined to carry information originating from higher layers using a set of resource elements. For the downlink channel, PDSCH is the downlink channel in NR that mainly carries data, while the physical downlink control channel (Physical Downlink Control Channel, PDCCH) is used to carry downlink control information (downlink control information, DCI). The control information may include scheduling decisions, information related to reference signal information, rules forming corresponding Transport Blocks (TBs) carried by the PDSCH, and power control commands. For the reference signal, the UE measures and feeds back characteristics of the radio channel using CSI-RS so that the BS can perform DL data transmission using proper modulation, code rate, beamforming, etc.
In the presence of N T Multiple transmit antennas and N R In multiple-input and multiple-output (MIMO) systems with multiple receive antennas, the input-output relationship can be described as y=hwx+nWhereiny、x、nIs a vector of received symbols, transmitted symbols and noise, H is the channel coefficient (N R xN T ) Matrix, W is the precoding matrix. Precoding matrices are used on the transmission symbols to improve performance. Consider a MIMO channel modeling the downlink of the cellular mobile communication system 100 of fig. 1. BS 101 is equipped with N T A number of transmit antennas, and the UEs (e.g., ue#1 and ue#2) each have N R And a plurality of receiving antennas. BS 101 passes through the precoding matrix on the time-frequency resource elementsW performs multi-antenna transmission to the UE. The precoding matrix is obtained by UE feedback after CSI-RS measurement. In addition to the precoding matrix, NR also allows a beamforming matrix W D Further enhancing performance and/or reducing feedback overhead. In this case, the precoding matrix W first maps the chip-wise transmission layers/streams to P antenna ports, beamforming matrix W D Further mapping P ports CSI-RS to N T And a transmitting antenna. In an embodiment of the invention, gNB uses the angle (spatial domain, SD) and delay (frequency domain, FD) reciprocity in the channel to derive the beamforming matrix W D 。
In FDD systems, the downlink CSI feedback overhead generally increases with the number of transmit antenna units (spatial domain, SDs) and the channel bandwidth (frequency domain, FD). To mitigate overhead, there is a need for a downlink channel measurement and reporting method in which CSI-RS can be directed to the primary SD and FD components in the propagation environment. In abstract terms, the SD basis vector represents the (arrival/departure) angle, while the FD basis vector represents the delay tap. Physically, the above procedure corresponds to beamforming CSI-RS into scatterers in the environment, where scattering is associated with angle and time delay. With partial channel reciprocity, the angle and delay in the DL channel can be obtained by UL channel measurements. Once completed, the UE only needs to measure and feedback the downlink CSI corresponding to the dominant angle and delay.
In order to obtain good throughput performance, a large number of dominant angles and delays need to be acquired, which results in a large number of beamformed CSI-RS ports for channel estimation. The space domain resolution of the channel is increased by a large number of dominant angles, so that the MIMO performance is improved. The large amount of dominant time delay increases the frequency domain resolution of the channel, thereby improving the frequency domain resource allocation performance. However, a large number of beamformed CSI-RS ports may increase CSI-RS overhead. According to one novel aspect, CSI measurement and reporting is proposed with good resolution in both SD and FD while maintaining reasonable CSI-RS overhead and CSI feedback overhead, as shown at 110 in fig. 1. In one embodiment, the UE reconstructs the DL channel over multiple delays using the DL channel estimated on several beamformed CSI-RS ports and the delay tap index signaled from the network. In another embodiment, the UE measures and reports CSI (PMI, CQI) for a subset of the signaling bandwidth of the DL channel.
Fig. 2 is a simplified block diagram of a base station 201 and user equipment 211 in a mobile communication network 200 implementing some embodiments of the present invention. For the base station 201, an antenna 221 transmits and receives radio signals. The RF transceiver module 208 is coupled to the antenna, receives RF signals from the antenna, converts them to baseband signals and sends the baseband signals to the processor 203. The RF transceiver 208 also converts the baseband signal received from the processor into an RF signal and transmits the RF signal to the antenna 221. The processor 203 processes the received baseband signals and invokes different functional modules to perform the features in the base station 201. Memory 202 includes a non-transitory computer readable storage medium or a volatile computer readable storage medium storing program instructions and data 209 to control the operation of the base station.
A similar configuration exists in the UE 211, where the antenna 231 transmits and receives RF signals. The RF transceiver module 218 is coupled to the antenna, receives an RF signal from the antenna, converts it to a baseband signal, and transmits the baseband signal to the processor 213. The RF transceiver 218 also converts the baseband signal received from the processor into an RF signal and transmits the RF signal to the antenna 231. The processor 213 processes the received baseband signals and invokes different functional modules to perform features in the UE 211. Memory 212 includes a non-transitory computer-readable storage medium or a volatile computer-readable storage medium storing program instructions and data 219 to control the operation of the UE.
The base station 201 and the UE 211 also include several functional modules and circuits to perform some embodiments of the present invention. The different functional modules are circuits that may be configured and implemented by software, firmware, hardware, or any combination thereof. The functional modules and circuits, when executed by the processors 203 and 213 (e.g., by executing program code 209 and 219), allow the base station 201 to schedule (via scheduler 204), pre-code (via pre-coder 205), encode (via MIMO encoding circuitry 206), and transmit control/configuration information and data (via control/configuration circuitry 207) to the UE 211, and allow the UE 211 to receive, decode (via MIMO circuitry 216) and beamform (via beamforming circuitry 215) the control/configuration information and data (via control/configuration circuitry 217) and perform channel estimation (via measurement/estimation circuitry 220) accordingly, for example. While maintaining reasonable CSI-RS overhead and CSI feedback overhead, CSI estimation and reporting mechanisms with good resolution are proposed in both SD and FD. In one example, the UE reconstructs the DL channel over multiple delays using DL channels estimated over several beamformed CSI-RSs and delay tap indices signaled from the network. In another example, the UE measures and reports CSI (PMI, CQI) for a subset of the signaling bandwidth of the DL channel.
For having N T Transmitter with multiple transmit antenna ports, N in OFDM system T The CSI-RS ports perform time/frequency/code multiplexing within one resource block, and one port occupies one time-frequency resource (one OFDM symbol×one subcarrier). Using these N T The UE may perform channel estimation in the "antenna" domain for CSI-RS ports. However, channel estimation may also be performed in the beam (angle) domain. Note that the channel may be compact (compact) in the beam domain, even though it may be rich (rich) in the antenna domain. The beam (angle) domain may be obtained from the antenna domain by linear transformation (e.g., DFT/SVD transformation (DFT beam/SVD beam, respectively)):
H b ＝HU SD
wherein the method comprises the steps of
Is N R ×N T The DL channel matrix is used for the channel,
is N in the beam domain R ×N T The DL channel matrix is used for the channel,
is N representing the antenna to beam (angle) domain transformation T ×N T A matrix. s is(s) t Is N T X 1 DFT/SVD vector.
Let the transmitter know two beams-s i Sum s j In the (downlink) channel. To estimate downlink beam domain channelsAnd->The transmitter transmits a reference signal vector s in the first and second CSI-RS ports, respectively i Sum s j . The two CSI-RS ports may be two orthogonal time instances or two orthogonal subcarriers or two orthogonal codes or a combination of time/frequency/codes. The channel estimation procedure can be expressed as:
the formula is the origin of the term "precoding/beamforming CSI-RS" because the original dual-port CSI-RS in the time/frequency/code domain is composed of N T X 2 matrix W SD ＝[s i s j ]"precoding" is performed. Using this precoded CSI-RS corresponds to the receiving end measuring N R X 2 effective channels HW SD . With knowledge of the dominant beam, the number of CSI-RS ports with "precoded" CSI-RS is from N T To two. In a cellular environment with one BS and multiple UEs per cell, each UE may use the same CSI-RS for estimating its downlink channel (cell-specific CSI-RS) for legacy CSI-RS. However, for precoded CSI-RS, since the primary beam of each UE may be different, the number of CSI-RS ports at the BS transmitter varies with the number of UEs (UE-specific CSI-RS). By configuring the UE to measure and report DL channels only in the dominant beam, a large amount of traffic can be avoidedAnd calculating and reporting. The BS may obtain knowledge of the dominant DL beam from the UL channel based on UL/DL channel reciprocity.
For the future standard of 5G NR, it is also intended to utilize the channel delay domain in addition to the beam domain to further reduce DL CSI computation and overhead. This is based on the fact that the channel may be compact in the time delay domain, even though it may be rich in the frequency domain. The frequency domain and the time delay domain are associated by a DFT transform. By configuring the UE to measure and report DL channels only in the primary delay taps, a large number of computations and reports can be avoided. Based on the fact that there is UL/DL reciprocity in the delay domain, the BS can obtain knowledge of the primary DL delay taps from the UL channel.
Fig. 3 illustrates a sequence flow for the entire process of CSI acquisition and reporting in accordance with one novel aspect. In step 311, the UE 302 transmits an uplink sounding reference signal (uplink sounding reference signal, UL SRS) to its serving base station BS 301. In step 312, BS 301 estimates UL channel H UL And BS uses angle (spatial domain, SD) and latency (frequency domain, FD) reciprocity to derive DL SD-FD based beamforming matrix W D 。N T X LSD base matrix W SD ＝[s 1 … s L ]And N 3 X M FD radical W FD ＝[f 1 … f M ]Respectively asHere, L represents the number of dominant beams, and M represents the number of dominant beams in the UL/DL channel. N (N) 3 Is the total number of frequency components in the channel. The frequency domain component may refer to a subcarrier, a resource block or a set of resource blocks. A set of resource blocks is referred to as a subband in 3GPP terminology. N (N) T N 3 X LM combined SD-FD base matrixObtained. In step 313, the BS 301 precodes (precompensates) the CSI-RS by the joint transform vector of the antenna to beam domain and frequency to delay domain. This means that the frequency subband n=0, 1, N 3 LM Port CSI-RS in-1 is represented by N T X LM matrix->Precoding and passing through N T And transmitting by using the antenna. BS 301 transmits the beamformed CSI-RS in the downlink to UE 302. It can be seen that BS 301 has estimated L dominant beams and M dominant delays and used them for CSI-RS precoding. Thus, UE 302 must be configured to measure LM beam delay pairs.
In step 321, the UE 302 measures the precoded CSI-RS and estimates the effective DL channel H. By using W D [n]CSI-RS in precoded subband N, UE measures dimension N R Effective DL channel H [ n ] of xLM]W D [n]Wherein H [ n ]]Is the dimension N in subband N R ×N T Is used for the actual DL channel of (a). N in the beam delay domain R The xLM channel is estimated by the UE asTo calculate the precoder (mapping from data streams to beams), the UE now forms M channel matrices, one for each delay tap. Mth m th The individual channel matrices are given by m=1, …, M, +.>To calculate the precoder on delay m=1, … M, the UE calculates SVD: />Then from V m The first R.ltoreq.L column of (1) gives the best precoder for data transmission, where R is the channel +.>Is a rank of (c). In order to compute the precoder on M delay taps, the UE needs to compute M SVDs. The M precoders are arranged in a single lm×r wideband (independent of the frequency index n=0, 1, … N 3 -1) precoder matrix V bd In (c), as follows:
wherein each V m Is an lxr precoder m=1, … M on a delay tap
The UE 302 calculates channel state information in the form of RI, PMI, CQI. In step 322, the UE 302 reports channel state information in the beam delay domain back to the BS 301. Each frequency subband n=0, 1, … N 3 The CQI in-1 is calculated as N estimated by the UE in subband N R X LM DL channel matrix H [ n ]]W D [n]Precoder V bd Is a function of (2). Operation W D [n]V bd Transforming the precoder in the beam-time delay domain into the antenna frequency domain, thus W D [n]V bd For channel H [ n ]]N of (2) T X R precoder. CSI reported to the BS includes the following: LM×R precoding matrix V bd Rank R and subband CQI (H [ n ]]W D [n]V bd )，n＝0，1，…N 3 -1, wherein f (·) is a function used by the UE to calculate CQI.
In step 331, the BS 301 obtains channel state information in a beam delay domain through UE feedback and applies a transform vector to obtain a precoder in an antenna frequency domain. BS 301 gets precoder V in the beam delay domain bd And linearly transforming the joint antenna frequency to the beam delayApplied to precoder V bd The method comprises the following steps of:
in step 341, the BS 301 transmits data to the UE 302 through the PDSCH using the precoder. For PDSCH transmission in subband N, the BS may use N T X R precoder W D [n]V bd Rank R and CQIf (H [ n ]]W D [n]V bd ) A modulation and coding scheme (modulation and coding scheme, MCS), a transport block size, etc. are determined. In step 342, the UE 302 performs channel estimation and demodulation accordingly.
Fig. 4 illustrates an uplink channel estimate with dominant beam and time delay and a corresponding downlink estimate in the beam time delay domain in accordance with a novel aspect. In the uplink, the BS receives SRS from the UE and determines the dominant SD-FD pair from the UL channel estimate. In the example of fig. 4, we assume that the BS further selects eight beam delay pairs (or SD-FD pairs) from the LM beam delay pairs (or SD-FD pairs), as previously described. Eight pairs (SD, FD) are (1, 2), (3, 3), (3, 6), (4, 1), (5, 5), (6, 1) and (6, 2). The network uses dominant SD-FD pairs for beamformed CSI-RS transmissions to the UE. The UE then measures the beam delay domain channel:
wherein the method comprises the steps of
N 3 Is the number of PMI subbands (frequency bins) in the channel bandwidth.
The single wideband precoder W is according to the channel H described above bd Calculated and reported to the BS. The subband CQI calculated at the UE is f (H n]W D [n]W). Then the network reconstructs the precoder W BS [n]＝W D [n]W，n＝0，1，…N 3 -1. Wideband reporting of PMI reduces frequency-dependent PMI overhead. In order to obtain good throughput performance, a large number of dominant angles and delays need to be acquired, which results in a large number of beamformed CSI-RS ports for channel estimation. Therefore, while maintaining reasonable CSI-RS overhead and CSI feedback overhead, CSI mechanisms with good resolution are proposed in both SD and FD.
Fig. 5 illustrates one embodiment of channel reconstruction using estimated channels on several beamformed CSI-RSs and signaled delay tap indices in accordance with one novel aspect. FD base (delay tap) with index m may be represented by DFT vectorRepresentation, where N 3 Is the number of PMI subbands. The other FD group l +.m can be expressed as +.>Where k=l-m. Based on uplink channel measurement, when the base station finds that two main delays are m and l in the same beam, only FD-based m-beam is needed to form CSI-RS and the offset k=l-m is indicated to the UE through dynamic signaling. Dynamic signaling support should depend on the channel profile. For slowly varying channels, it is sufficient to add the offset signaling bits by RRC message. MAC-CE or DCI signaling may be enabled for more rapidly changing channels. The UE may reconstruct the channel on those delays not used for beamforming CSI-RS using the indicated offset.
In the example of fig. 5, p=8 CSI-RS ports→8 dominant SD-FD groups (basic) determined from the UL channel. In addition to FD group 0, an additional FD group (e.g., FD group 2) is configured for the UE. The UE measures the effective 16 SD-FD pairs through p=8 CSI-RS ports and 2 FD groups, 0 and 2. F is removed 0 In addition, an additional FD group f is configured to the UE m N constructed by UE R The x 2P effective DL channel is as follows:
considering single layer transmission without loss of generality, the UE reports a 2p×1 linear combination coefficient vector to merge 2P ports into one transport layer
v＝[v 11 v 12 … v 1p v 21 v 22 … v 2p ] T
N for single layer transmission in subband N T The x 1 precoder is
This corresponds to
Part of the UE report isAnd W is D [n]Is used by the base station to precode P-port CSI-RS. Representing a matrix of P×2 linear combination coefficients as
And N is 3 The X2 FD base matrix is W f ＝[f 0 f m ]The precoder for all subbands reported by the UE may be written asWherein W is 1 Is a P x P identity matrix.
The above embodiments may be applied to codebook-based precoding supported by the 5G NR standard. It has been agreed in the 5G NR standard that for Port Selection (PS) codebook enhancement with angle and/or latency DL/UL reciprocity, a codebook structure is supportedWherein W is 1 Is a free choice matrix, has an identity matrix as a special configuration,is a DFT-based compressed matrix, where N 3 ＝N CQIsubband X R is the number of PMI subbands, M represents the number of frequency domain base vectors, supporting M e {1,2}. When m=2, for W f The quantified FD groups are limited to a single window of size N configured to the UE by the RRC parameter valueOfN. The FD basis in the window is contiguous with the orthogonal DFT matrix.
FIG. 6 illustrates measurement and reporting in accordance with a novel aspectOne embodiment of a subset of channel state information (e.g., PMI, CQI) of the signaling bandwidth. The FD base used in CSI-RS precoding corresponds to the entire bandwidth. UE slaveThe effective DL channels over the entire BW are processed to obtain the wideband precoder. However, for frequency dependent resource allocation, the scheduler only needs CSI reports from a subset of the bandwidth. In the example of FIG. 6, consider the case of N 3 Two UEs are scheduled in 8 subbands, with UE1 expected to report CSI for the first 4 subbands and UE2 expected to report CSI for the last 4 subbands. By SD-FD precoding the P-port CSI-RS for each UE, the CSI-RS overhead is the 2P CSI-RS port in each frequency unit (subband/RB/.). To avoid this, the base station may use the non-zero number of bits in the 5G NR RRC parameter "csi-ReportingBand" field (this number is denoted by NC) to calculate the FD base vector. That is, the base station may calculate a length of N C FD base vector of (a). The FD base vector is used for generating a corresponding N C The CSI-RS is precoded in the subbands. The UE may decode the "csi-ReportingBand" field to process the valid downlink channel and calculate and report the corresponding N C Wideband precoder for individual subbands.
For example, consider N 3 ＝8，Antenna to beam conversion->Is obtained from the UL channel estimate of the BS. Representing the estimated UL channel at BS from the fourth sub-band 1 as
For these 4 sub-band channels, the BS finds the dominant DFT FD baseThe first 4 subbands are transformed from the antenna frequency domain to the beam delay domain as a whole +.>Wherein p=k S K F 。/>Can be written as:
and each ofFor precoding P-port CSI-RS in subband n=0, 1,2, 3. The estimated UL channel from the last 4 subbands at the BS is expressed as:
for these 4 sub-band channels, the BS finds the dominant DFT FD baseThe final 4 subbands are transformed from the antenna frequency domain to the beam delay domain as a whole +.>Similar to before, eachFor precoding P-port CSI-RS in subbands n=4, 5,6, 7.
At the UE, DL beam delay channels corresponding to the first 4 subbands and the last 4 subbands are estimated as:
this is equivalent to the UE approximating the first 4 subbands and the last 4 subbands, respectively, as wideband channels. P×R precoder W corresponding to the first 4 subbands and the last 4 subbands (1) And W is (2) From the corresponding channelAnd->Obtained by the method. The subband CQI is found to be:
for n=0, 1,2,3
For n=4, 5,6,7
The UE reports the precoder W found above to the BS (1) ，、W (2) A rank indicator R and a subband CQI. The BS reconstructs the subband PMI for data transmission as:
for n=0, 1,2,3
For n=4, 5,6,7
In this way, the CSI-RS overhead is reduced to P in each frequency unit.
Fig. 7 is a flow diagram of a method of CSI acquisition and reporting from the perspective of a UE in accordance with one novel aspect. In step 701, the UE transmits an SRS to the BS through an UL channel in the FDD network. In step 702, the UE receives CSI-RS through a DL channel.CSI-RS ports for CSI-RS transmission pass through precoding matrix W derived from SRS D Mapped to the corresponding BS transmit antenna. In step 703, the UE receives one or more frequency domain base indexes from the BS. In step 704, the UE estimates CSI of the DL channel using the received frequency domain base index information and the precoded CSI-RS. In step 705, the UE reports the estimated CSI to the BS for subsequent DL transmissions. The estimated CSI includes RI, PMI and CQI.
Although the invention has been described in connection with certain specific embodiments for instructional purposes, the invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of the various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.
Claims (17)
1. A method of downlink channel state information measurement and reporting, comprising:
transmitting, by a user equipment, a sounding reference signal to a base station through an uplink channel in a frequency division duplex network;
receiving a channel state information reference signal through a downlink channel, wherein a channel state information reference signal port for channel state information reference signal transmission passes through a precoding matrix W D Mapping to corresponding base station transmitting antennas;
receiving an indication from the base station of a precoding matrix W relative to the channel state information reference signal D One or more frequency domain base indexes of delay offsets of the frequency domain base vectors in (a);
estimating channel state information of the downlink channel using the received frequency domain base index information and the precoded channel state information reference signal; and
reporting the estimated channel state information to the base station for subsequent downlink transmissions.
2. The method of claim 1, wherein the user device is configured to receive the precoded channel state information reference signal, wherein the precoding is performed by the user deviceMatrix W D The channel state information reference signal ports mapped to the respective base station transmit antennas comprise a subset of spatial and frequency domain basis vectors derived from sounding reference signals.
3. The method of claim 1 wherein the user equipment estimates the channel state information by reconstructing the downlink channel using the precoded channel state information reference signal and the received frequency-domain base index information.
4. The method of claim 1, wherein the user device reports the estimated channel state information comprising at least one of a rank indicator, a precoding matrix indicator, and a channel quality indicator to the base station.
5. The method according to claim 1, characterized in that the user equipment is configured to measure the precoded channel state information reference signal for a subset of the signaling bandwidth of the downlink channel and to estimate the channel state information.
6. A user equipment for downlink channel state information measurement and reporting, comprising:
a transmitter for transmitting a sounding reference signal to a base station through an uplink channel in a frequency division duplex network;
a receiver for receiving a channel state information reference signal through a downlink channel, wherein a channel state information reference signal port for channel state information reference signal transmission passes through a precoding matrix W D Mapped to a base station transmit antenna, and wherein the receiver further receives an indication from a base station relative to the channel state information reference signal precoding matrix W D One or more frequency domain base indexes of delay offsets of the frequency domain base vectors in (a);
a channel estimation circuit for estimating channel state information of the downlink channel using the received frequency domain base index information and the precoded channel state information reference signal; and
control circuitry for reporting the estimated channel state information to the base station for subsequent downlink transmissions.
7. The user equipment of claim 6, wherein the user equipment is configured to receive the precoded channel state information reference signal by the precoding matrix W D The channel state information reference signal ports mapped to base station transmit antennas comprise a subset of spatial and frequency domain basis vectors derived from sounding reference signals.
8. The user equipment of claim 6, wherein the user equipment estimates the channel state information by reconstructing the downlink channel using the precoded channel state information reference signal and the received frequency-domain base index information.
9. The user device of claim 6, wherein the user device reports the estimated channel state information comprising at least one of a rank indicator, a precoding matrix indicator, and a channel quality indicator to the base station.
10. The user equipment of claim 6, wherein the user equipment is configured to measure the precoded channel state information reference signal for a subset of the signaling bandwidth of the downlink channel and estimate the channel state information.
11. A method of downlink channel state information measurement and reporting, comprising:
receiving, by a base station, a sounding reference signal from a user equipment over an uplink channel in a frequency division duplex network;
constructing and transmitting channel shapes to the user equipment through a downlink channelStatus information reference signals, wherein the channel status information reference signal ports pass through a precoding matrix W D Mapping to a base station transmitting antenna;
providing one or more frequency domain base indexes to the user equipment, wherein the one or more frequency domain base indexes represent a precoding matrix W relative to the channel state information reference signal D Time delay offset of the frequency domain base vector; and
estimated channel state information of the downlink channel is received from the user equipment and a subsequent downlink transmission is determined.
12. The method according to claim 11, characterized by passing through the precoding matrix W D The channel state information reference signal ports mapped to base station transmit antennas comprise a subset of spatial and frequency domain basis vectors derived from the sounding reference signals.
13. The method of claim 11 wherein said channel state information is estimated by reconstructing said downlink channel using a precoded channel state information reference signal and said received frequency domain base index information.
14. The method of claim 11, wherein the base station receives the estimated channel state information for the downlink channel from the user device, wherein the estimated channel state information comprises at least one of a rank indicator, a precoding matrix indicator, and a channel quality indicator.
15. The method according to claim 11, wherein the base station configures the user equipment to measure the precoded channel state information reference signals for a subset of the signaling bandwidth of the downlink channel and estimate the channel state information.
16. A user equipment for downlink channel state information measurement and reporting, comprising:
a processor coupled to a memory, the memory having stored therein program instructions and data which, when executed by the processor, cause the user equipment to perform the method of any of the preceding claims 1-5, 11-15.
17. A non-transitory computer readable storage medium storing program instructions and data which, when executed by a processor of a user equipment for downlink channel state information measurement and reporting, cause the user equipment to perform the method of any of the preceding claims 1-5, 11-15.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101400074A (en) * | 2007-09-28 | 2009-04-01 | 夏普株式会社 | Method, user equipment and system for reducing feedback quantity of pre-coding matrix index number |
| CN107925457A (en) * | 2015-04-08 | 2018-04-17 | 株式会社Ntt都科摩 | For determining base station, user apparatus and the method for pre-coding matrix |
| CN109757127A (en) * | 2017-09-08 | 2019-05-14 | Lg电子株式会社 | Method and device thereof for reporting channel status information in a wireless communication system |
| CN110050450A (en) * | 2017-05-05 | 2019-07-23 | 联发科技股份有限公司 | The method and device of channel state information is obtained using channel reciprocity |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160006553A1 (en) * | 2013-02-24 | 2016-01-07 | Lg Electronics Inc. | Method and apparatus for reporting downlink channel state |
| US10812238B2 (en) * | 2016-04-20 | 2020-10-20 | Convida Wireless, Llc | Configurable reference signals |
-
2022
- 2022-01-10 TW TW111100886A patent/TWI797952B/en active
- 2022-01-18 CN CN202210057606.3A patent/CN114826444B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101400074A (en) * | 2007-09-28 | 2009-04-01 | 夏普株式会社 | Method, user equipment and system for reducing feedback quantity of pre-coding matrix index number |
| CN107925457A (en) * | 2015-04-08 | 2018-04-17 | 株式会社Ntt都科摩 | For determining base station, user apparatus and the method for pre-coding matrix |
| CN110050450A (en) * | 2017-05-05 | 2019-07-23 | 联发科技股份有限公司 | The method and device of channel state information is obtained using channel reciprocity |
| CN109757127A (en) * | 2017-09-08 | 2019-05-14 | Lg电子株式会社 | Method and device thereof for reporting channel status information in a wireless communication system |
Non-Patent Citations (2)
| Title |
|---|
| 3GPP.Technical Specification Group Radio Access Network * |
| NR ; Physical layer procedures for control (Release 15).3GPP TS 38.213 V15.12.0 (2020-12).2020,全文. * |
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