CN113572506A - High-speed rail multi-TRP wireless communication method based on FDD precoding - Google Patents

High-speed rail multi-TRP wireless communication method based on FDD precoding Download PDF

Info

Publication number
CN113572506A
CN113572506A CN202110609714.2A CN202110609714A CN113572506A CN 113572506 A CN113572506 A CN 113572506A CN 202110609714 A CN202110609714 A CN 202110609714A CN 113572506 A CN113572506 A CN 113572506A
Authority
CN
China
Prior art keywords
angle
precoding
rru
uplink
downlink
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110609714.2A
Other languages
Chinese (zh)
Other versions
CN113572506B (en
Inventor
吉荣新
王东明
陈建平
胡静
王超
宋铁成
王海龙
钱承晖
王�琦
刘瑜
倪小龙
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nanjing Ticom Tech Co ltd
Southeast University
Original Assignee
Nanjing Ticom Tech Co ltd
Southeast University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nanjing Ticom Tech Co ltd, Southeast University filed Critical Nanjing Ticom Tech Co ltd
Priority to CN202110609714.2A priority Critical patent/CN113572506B/en
Publication of CN113572506A publication Critical patent/CN113572506A/en
Application granted granted Critical
Publication of CN113572506B publication Critical patent/CN113572506B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0417—Feedback systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/0478—Special codebook structures directed to feedback optimisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/063—Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention provides a high-speed rail multi-TRP wireless communication method based on FDD precoding, which comprises the following steps: designing a pilot frequency sequence to estimate the angle information of an uplink channel; designing a correction algorithm to correct the downlink angle direction; selecting a code word and feeding back an index of the code word; precoding and transmitting information are designed. The precoding design method based on the channel angle reciprocity can greatly reduce the system training and feedback overhead, improve the robustness of the system and improve the communication quality.

Description

High-speed rail multi-TRP wireless communication method based on FDD precoding
Technical Field
The invention relates to the technical field of wireless communication, in particular to a high-speed rail multi-TRP wireless communication method based on FDD precoding.
Background
As the demand for high-speed rail wireless communication services increases worldwide, the concurrent proliferation of multiple services makes communication network capacity a huge challenge. In consideration of future railway internet of things and big data application, the development of a railway 5G private network (5G-R) mobile communication system is trending. Due to low latency and high reliability requirements, the 5G-R private network employs Frequency Division Duplex (FDD) mode. To further increase the capacity of the system, the multi-antenna technology is also considered as a key technology of 5G-R. However, in the FDD system, uplink and downlink are in different frequency bands, and with the fast movement of a high-speed rail, the channel is usually time-varying, and the Channel State Information (CSI) obtained by sending the pilot frequency is aged too fast, so that the uplink CSI and the downlink CSI no longer have direct reciprocity. Therefore, for an FDD MIMO system in a high-speed rail multi-TRP wireless communication process, how to acquire precoding and further improve the performance of the system is a bottleneck problem.
Disclosure of Invention
The invention provides a high-speed rail multi-TRP wireless communication method based on FDD precoding, aiming at solving the problems in the prior art, the size and the feedback precision of a codebook can be reasonably selected according to the practical conditions of user angle domain channel information and the like, the system overhead is greatly reduced, the system performance is improved, and the communication effect is improved.
1) Acquiring angle information theta of a pilot frequency sequence estimation uplink channel;
on the basis of a high-speed railway moving scene, setting a channel model as an LOS path and an NLOS path, wherein the LOS path obeys Rice distribution, the NLOS component obeys generalized stable uncorrelated scattering, assuming that a user terminal is positioned in a train, the communication is carried out through a carriage antenna array relay station, an antenna array adopts a uniform array, firstly, demultiplexing signals at an RRU end to obtain a single MRS to RRU sending signal, estimating by utilizing the difference of the RRU antenna array receiving signals to obtain an estimated angle theta corresponding to the MRS to the RRU, and averagely reducing errors of an angle estimation result through the distance relation among a plurality of MRSs to obtain uplink angle information theta from each MRS to the RRU;
2) correcting the downlink angle direction by using a correction algorithm to obtain a corrected downlink angle
Figure BDA0003095187820000011
2.1) respectively substituting the uplink angle information theta into uplink and downlink direction vectors of the antenna array spacing d and the array antenna number M:
Figure BDA0003095187820000021
2.2) adding a correction angle to the downstream vector
Figure BDA0003095187820000022
Figure BDA0003095187820000023
2.3) the angle to be corrected when the vector deviation in the up-down direction is minimum is determined by the following formula
Figure BDA00030951878200000211
Figure BDA0003095187820000024
3) Selecting a code word and feeding back an index of the code word;
3.1) the corrected down angle obtained in step 2)
Figure BDA0003095187820000025
On the basis, corresponding channel direction information matrix is constructed according to the antenna array form used
Figure BDA0003095187820000026
3.2) in calculating
Figure BDA0003095187820000027
Then, the code book is combined with a preset code book set
Figure BDA0003095187820000028
The following is calculated:
Figure BDA0003095187820000029
wherein j is the corresponding codeword index;
4) designing precoding and transmitting information;
after obtaining the corresponding codeword index, the base station side will use the codeword to precode the message and send the message, at this moment, the signal received at the user side is:
Figure BDA00030951878200000210
wherein h isdIndicating downlink channel information CSI, XsAnd the base station side is a pre-coded transmission sequence.
The invention has the beneficial effects that: the FDD precoding design method based on the channel angle reciprocity can reasonably select the size and the feedback precision of the codebook according to the practical conditions of the user angle domain channel information and the like, greatly reduces the system overhead, improves the system performance and improves the communication effect.
Drawings
Fig. 1 is a simulation diagram of the FDD uplink and downlink arrival angle deviation under different uplink and downlink frequency intervals.
FIG. 2 is a comparison simulation diagram of the magnitude deviation of the vector in the forward and backward directions before and after the angle correction according to the method of the present invention.
Detailed Description
The invention will be further explained with reference to the drawings.
The precoding design method based on the reciprocity of the channel angle domain is applied to an FDD system in a high-speed rail multi-TRP scene, and is improved aiming at the defects of the traditional precoding design method.
The research scene of the invention is based on a high-speed railway moving scene, and the user terminal is supposed to be positioned in a train and communicates through a carriage antenna array relay station. The train at a certain position is analyzed, and the antenna array of the train is assumed to have KtrThe root antenna and the base station have N in totalAAnd one RRU. Taking a certain position as a starting point, and setting a sampling interval as T under the condition of constant large-scale fading, Rice K factor and Doppler frequency shiftsAnd an uplink channel from the kth antenna to the a-th RRU on the nth sampling point train is as follows:
Figure BDA0003095187820000031
wherein vk,aRandom phase shifts for directed paths obey a uniform distribution between 0 and 2 pi. Beta is ak,aIs large-scale fading from the kth antenna to the a-th RRU on the train at the position, Kk,aThe Rice K factor from the K antenna to the a RRU on the train at the position
Figure BDA0003095187820000032
pLOS,k,aAnd the probability that a direct path is formed between the kth antenna and the a-th RRU on the train is shown. a isk,aFor the direction vector from the kth antenna to the a-th RRU on the train at the position, when the antenna array adopts a uniform array (ULA), M antennas are arrangedThe elements are arranged in a straight line, and assuming that the spacing between the antenna elements is d, the incident angle of the signal is thetak(K-1, 2, … K), a phase difference Δ d-d sin θ exists between the received signals of two adjacent antenna elementskThe direction vector of the array at this time is:
Figure BDA0003095187820000033
fk,a(nTs) The influence of the Doppler from the kth antenna to the a-th RRU on the train at the position is the elapsed time nTsPost-generated phase rotation [4]Expressed as:
Figure BDA0003095187820000041
vtras a velocity vector of the train at that location, θk,a,lIs the included angle between the speed vector and the real-time position of the train.
Figure BDA0003095187820000042
Is a non-direct component in which the elements are independently distributed
Figure BDA0003095187820000043
Assuming that the non-direct component is subject to generalized stationary uncorrelated scattering, then
Figure BDA0003095187820000044
Wherein
Figure BDA0003095187820000045
Maximum Doppler shift, J0(. cndot.) is a first class of zeroth order Bessel function.
The following table shows general parameters of the system, and precoding design is performed according to the system parameters in table 1.
TABLE 1 System simulation parameters
Figure BDA0003095187820000046
After receiving MRS sending signals at the RRU side, demultiplexing the signals to obtain a signal X sent by a single MRS and received at the RRU. Firstly, a covariance matrix of array receiving signals is calculated:
Figure BDA0003095187820000047
performing eigenvalue decomposition on the covariance matrix, corresponding to the eigenvalue of Lambda, and obtaining a signal subspace UsNoise subspace UnGiven by:
Rx＝UΛUH
λ1≥λ2≥...≥λP＝...＝λM＝σ2
Us＝[u1 u2 ... uP]
Un＝[uP+1 uP+2 ... uM]
wherein u isiAs a characteristic value λiThe corresponding feature vector.
A spatial spectrum of the following formula is constructed and the peak maxima are searched. The uplink angle estimation information is θ that maximizes the following equation:
Figure BDA0003095187820000051
θ＝arg max P(θ)
under the condition of a plurality of RRUs and MRSs, the angle estimation information of the mth RRU to the nth MRS is theta(m,n). Keeping the angle estimation information at [ -60 °,60 ° ]]The result of (1). Distance of MRS of train is lMRSRRU distance is lRRUThen the train position estimated by the estimation information is
Z(m,n)＝ltan(θ(m,n))-(m-1)lMRS+(n-1)lRRU
Then, the estimation result of the train position is averagely reduced by a plurality of RRUs (remote radio units), and ckFor the effective number of the k RRU to MRS angle estimation, the estimation result of the plurality of RRUs to the train position can be obtained as
Figure BDA0003095187820000052
After the train position estimation information is obtained, the train position estimation information can be obtained through the following reverse thrust
Figure BDA0003095187820000053
After the uplink angle information theta is obtained, the uplink angle information theta is respectively substituted into uplink and downlink direction vectors of the antenna array distance d and the array antenna number M:
Figure BDA0003095187820000061
adding a correction angle to the downlink vector
Figure BDA0003095187820000062
Figure BDA0003095187820000063
Then, the following formula is used to calculate the angle to be corrected when the vector deviation in the up and down direction is minimum
Figure BDA0003095187820000064
Figure BDA0003095187820000065
As shown in fig. 1, the angle deviation between the uplink and downlink increases with the increase of the frequency interval, and since the down-link directional vector angle and the up-link maximum deviation are 22 ° when the frequency interval is 200MHz, it is necessary to correct the down-link angle if it is desired to use the reciprocity of the up-link angle.
As shown in fig. 2, after the angle correction is performed by the method of the present invention, the amplitude deviation of the uplink and downlink vectors is greatly reduced compared with that before the correction, so as to provide a good cushion for the subsequent transmission.
The base station side obtains the corrected angle information
Figure BDA0003095187820000066
Then, firstly, the corresponding downlink channel information matrix is constructed by the following formula
Figure BDA0003095187820000067
Figure BDA0003095187820000068
Then selecting a specific code word vector w satisfying the maximum signal-to-noise ratio principle from a preset codebookj. The corresponding codeword vector index j is obtained by:
Figure BDA0003095187820000069
and after determining the used code word vector index, the base station side uses the code word to send the precoding information to the user. The signal received at the user side is represented as:
Figure BDA0003095187820000071
wherein h isdIndicating downlink channel information CSI, XsAnd the base station side is a pre-coded transmission sequence.
While the invention has been described in terms of its preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims (2)

1. A high-speed rail multi-TRP wireless communication method based on FDD precoding is characterized by comprising the following steps:
1) acquiring angle information theta of a pilot frequency sequence estimation uplink channel;
on the basis of a high-speed railway moving scene, setting a channel model as an LOS path and an NLOS path, wherein the LOS path obeys Rice distribution, the NLOS component obeys generalized stable uncorrelated scattering, assuming that a user terminal is positioned in a train, the communication is carried out through a carriage antenna array relay station, an antenna array adopts a uniform array, firstly, demultiplexing signals at an RRU end to obtain a single MRS to RRU sending signal, estimating by utilizing the difference of the RRU antenna array receiving signals to obtain an estimated angle theta corresponding to the MRS to the RRU, and averagely reducing errors of an angle estimation result through the distance relation among a plurality of MRSs to obtain uplink angle information theta from each MRS to the RRU;
2) correcting the downlink angle direction by using a correction algorithm to obtain a corrected downlink angle
Figure FDA0003095187810000011
3) Selecting a code word and feeding back an index of the code word;
3.1) the corrected down angle obtained in step 2)
Figure FDA0003095187810000012
On the basis, corresponding channel direction information matrix is constructed according to the antenna array form used
Figure FDA0003095187810000013
3.2) in calculating
Figure FDA0003095187810000014
Then, the code book is combined with a preset code book set
Figure FDA0003095187810000017
The following is calculated:
Figure FDA0003095187810000015
wherein j is the corresponding codeword index;
4) designing precoding and transmitting information;
after obtaining the corresponding codeword index, the base station side will use the codeword to precode the message and send the message, at this moment, the signal received at the user side is:
Figure FDA0003095187810000016
wherein h isdIndicating downlink channel information CSI, XsAnd the base station side is a pre-coded transmission sequence.
2. The FDD precoding based high-speed multi-TRP wireless communication method according to claim 1, wherein: the correction algorithm in the step 2) comprises the following specific processes:
2.1) respectively substituting the uplink angle information theta into uplink and downlink direction vectors of the antenna array spacing d and the array antenna number M:
Figure FDA0003095187810000021
2.2) adding a correction angle to the downstream vector
Figure FDA0003095187810000022
Figure FDA0003095187810000023
2.3) the angle to be corrected when the vector deviation in the up-down direction is minimum is determined by the following formula
Figure FDA0003095187810000024
Figure FDA0003095187810000025
CN202110609714.2A 2021-06-01 2021-06-01 High-speed rail multi-TRP wireless communication method based on FDD precoding Active CN113572506B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110609714.2A CN113572506B (en) 2021-06-01 2021-06-01 High-speed rail multi-TRP wireless communication method based on FDD precoding

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110609714.2A CN113572506B (en) 2021-06-01 2021-06-01 High-speed rail multi-TRP wireless communication method based on FDD precoding

Publications (2)

Publication Number Publication Date
CN113572506A true CN113572506A (en) 2021-10-29
CN113572506B CN113572506B (en) 2022-09-16

Family

ID=78160986

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110609714.2A Active CN113572506B (en) 2021-06-01 2021-06-01 High-speed rail multi-TRP wireless communication method based on FDD precoding

Country Status (1)

Country Link
CN (1) CN113572506B (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014101170A1 (en) * 2012-12-31 2014-07-03 上海贝尔股份有限公司 Channel reciprocity compensating method and device in fdd system
CN106302274A (en) * 2016-08-26 2017-01-04 清华大学 A kind of extensive mimo system multiuser channel is estimated and tracking
CN107360108A (en) * 2017-08-10 2017-11-17 电子科技大学 The extensive MIMO Multi User Adaptives low complex degree channel estimations of FDD
CN107911153A (en) * 2017-10-31 2018-04-13 东南大学 A kind of down channel method for reconstructing based on uplink CSI towards FDD system
CN108880774A (en) * 2018-07-11 2018-11-23 郑州航空工业管理学院 Frequency division duplex multi-user large-scale multi-antenna system and its down-bound pilot frequency signal Design of length method
CN108989249A (en) * 2018-06-26 2018-12-11 南京邮电大学 A kind of extensive MIMO Beam Domain channel tracking method under high-speed rail scene
CN110943767A (en) * 2019-11-08 2020-03-31 杭州电子科技大学 Precoding design method based on channel part reciprocity in FDD large-scale MIMO system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014101170A1 (en) * 2012-12-31 2014-07-03 上海贝尔股份有限公司 Channel reciprocity compensating method and device in fdd system
CN106302274A (en) * 2016-08-26 2017-01-04 清华大学 A kind of extensive mimo system multiuser channel is estimated and tracking
CN107360108A (en) * 2017-08-10 2017-11-17 电子科技大学 The extensive MIMO Multi User Adaptives low complex degree channel estimations of FDD
CN107911153A (en) * 2017-10-31 2018-04-13 东南大学 A kind of down channel method for reconstructing based on uplink CSI towards FDD system
CN108989249A (en) * 2018-06-26 2018-12-11 南京邮电大学 A kind of extensive MIMO Beam Domain channel tracking method under high-speed rail scene
CN108880774A (en) * 2018-07-11 2018-11-23 郑州航空工业管理学院 Frequency division duplex multi-user large-scale multi-antenna system and its down-bound pilot frequency signal Design of length method
CN110943767A (en) * 2019-11-08 2020-03-31 杭州电子科技大学 Precoding design method based on channel part reciprocity in FDD large-scale MIMO system

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
HONGXIANG XIE: "UL/DL Channel Estimation for TDD/FDD Massive MIMO Systems Using DFT and Angle Reciprocity", 《 2016 IEEE 83RD VEHICULAR TECHNOLOGY CONFERENCE》 *
周蕾: "FDD大规模MIMO系统基于角度域稀疏性和互易性的信道估计与传输方法研究", 《中国优秀硕士学位论文全文数据库 (信息科技辑)》 *

Also Published As

Publication number Publication date
CN113572506B (en) 2022-09-16

Similar Documents

Publication Publication Date Title
AU2020261763B2 (en) Methods and systems for hybrid beamforming for mimo and miso communications
US8116698B2 (en) Generalized MIMO-beamforming weight estimation
EP1358722B1 (en) Radio communication system
CN107453795B (en) Beam allocation method of multi-user millimeter wave communication system, device and system thereof
US10205491B2 (en) System and method for large scale multiple input multiple output communications
CN106452539B (en) Hybrid beam forming method and device
US9252864B2 (en) Method and apparatus for fast beam-link construction in mobile communication system
US8891648B2 (en) System for transmitting and receiving channel state information
CN107911153B (en) FDD system-oriented downlink channel reconstruction method based on uplink CSI
US10644773B2 (en) Feedback channel information using pre-coders in a wireless communication system
CN105245310B (en) Method and system for processing downlink pilot signal
US8280426B2 (en) Adaptive power balancing and phase adjustment for MIMO-beamformed communication systems
WO2011131117A1 (en) Method and device for reporting antenna calibration information and determining antenna calibration factor
CN108881074B (en) Broadband millimeter wave channel estimation method under low-precision hybrid architecture
US9166662B1 (en) Methods and apparatus for antenna spoofing
CN102215186A (en) Time varying TDD-MIMO (Time Division Duplex-Multiple Input Multiple Output) channel reciprocity compensating method based on LS-SVM (Least Square Support Vector Machine)
US8615049B2 (en) Method and apparatus for controlling co-channel interference in a wireless communication system
CN102783047A (en) Method and device for feeding back pre-coding matrix index of dual-polarized antenna
Gao et al. Beampattern-based tracking for millimeter wave communication systems
US7876715B1 (en) Beamforming multiple-input multiple-output wireless techniques using spatial decomposition for frequency division duplex systems
CN101944981A (en) Method for acquiring status information of medium- and long-term channel of communication system
CN114221838A (en) Channel estimation method and system using channel conjugate data in large-scale MIMO system
Oh et al. A new RF beam training method and asymptotic performance analysis for multi-user millimeter wave systems
CN113572506B (en) High-speed rail multi-TRP wireless communication method based on FDD precoding
CN110912588A (en) Downlink time-varying channel prediction method based on improved Prony method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant