WO2008052010A2 - Method for obtaining a covariance matrix of a transmitting channel in a wireless network - Google Patents
Method for obtaining a covariance matrix of a transmitting channel in a wireless network Download PDFInfo
- Publication number
- WO2008052010A2 WO2008052010A2 PCT/US2007/082300 US2007082300W WO2008052010A2 WO 2008052010 A2 WO2008052010 A2 WO 2008052010A2 US 2007082300 W US2007082300 W US 2007082300W WO 2008052010 A2 WO2008052010 A2 WO 2008052010A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- matrix
- transmitting
- channel
- receiving
- response
- 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.)
- Ceased
Links
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
Definitions
- the quality of downlink signals received by a mobile station is determined by beamforming weighting vectors of a downlink channel.
- BTS base transceiver station
- FDD frequency division duplex
- One way to address the issue is to develop a probing-and-feedback mechanism to obtain channel coefficients of a downlink channel.
- Employing a probing-and-feedback mechanism is not a preferred solution as it requires redesigning wireless communication protocols and incurs a large amount of overhead.
- a probing-and-feedback mechanism is only applicable to environments with slow fading channels.
- Another way is to compute beamforming weighting vectors for a downlink channel by using a downlink channel covariance matrix that is transformed from an uplink channel covariance matrix.
- most of the algorithms that transform an uplink channel covariance matrix into a downlink channel covariance matrix suffer from high computation complexity.
- the present invention disclosed a method for transforming a covariance matrix of a receiving channel into a covariance matrix of a transmitting channel in a wireless network employing frequency division duplex.
- the method comprises calculating a speculative transformation matrix, generating a covariance matrix of a receiving channel, and transforming the covariance matrix of the receiving channel into a covariance matrix of a transmitting channel using the speculative transformation matrix.
- FIG. 1 is a flow chart diagram illustrating a method in accordance with the present invention
- the present invention discloses a method that transforms a covariance matrix of a receiving channel into a covariance matrix of a transmitting channel in a wireless network employing frequency division duplex (FDD). Subsequently, the covariance matrix of the transmitting channel is used to compute beamforming weighting vectors of the transmitting channel.
- FDD frequency division duplex
- the algorithm disclosed in the present invention improves the efficiency of computing beamforming weighting vectors in systems such as Macrocell/Microcell FDD OFDMA (Orthogonal Frequency Division Multiple Access). It performs well even when severe multi-path interference exists.
- Macrocell/Microcell FDD OFDMA Orthogonal Frequency Division Multiple Access
- FIG. 1 is a flow chart diagram illustrating a method in accordance with the present invention.
- the method begins with step 110 of creating a speculative transformation matrix without prior knowledge of the direction of arrival (DOA), ⁇ .
- a speculative transformation matrix C ⁇ is determined by a predetermined number of system parameters such as the number of antennas, the spacing of antennas, the number of sectors, uplink and downlink carrier frequencies, etc.
- the speculative transformation matrix C 1 is an M by M matrix (see step 110).
- An array-steering vector A( ⁇ , ⁇ ) also known as an array response vector, is defined according to the arrangement of an antenna array. It is a function of the direction of arrival (DOA) of receiving signals, denoted as ⁇ , and the wavelength of a wireless channel, denoted as ⁇ . If the antenna array is a uniform linear array (ULA), which is arranged linearly, then A( ⁇ , ⁇ ) is equal to
- A( ⁇ , ⁇ ) [l , where D is the distance between two adjacent antennas.
- the antenna array is a uniform circular array (UCA), which is arranged circularly, then A ⁇ , ⁇ ) is equal to
- A( ⁇ , ⁇ ) [e ⁇ e ⁇ M • • • • e *- M f , where r is the radius of a circular array.
- a response matrix is represented by the following equation:
- each sector is a pie shape.
- Each sector covers a region with a vertex angle of 2 ⁇ /N sector . In other words, it spans from angle ⁇ /N sector to angle ⁇ /N sector . Let ⁇ equal ⁇ /N sector .
- a sector is further divided into N a partitions of the same size.
- the transmitting and receiving response matrices of each partition are calculated according to equation 1.
- the DOA of the i-th partition, denoted as ⁇ equals (z - 1) ⁇ - ⁇ .
- the cumulative transmitting and receiving response matrices are defined by the following equations respectively.
- R n . be a covariance matrix of a receiving channel.
- the average covariance matrix of the receiving channel is computed according to the following equation:
- R n . — ⁇ e H i rx (H i rx ) H , where N e is the number of samples and N e is between [1, ⁇ ) .
- step 140 the covariance matrix of the transmitting channel is used to compute a transmitting beamforming weighting vector W 1x by finding the principal eigenvector of a channel covariance matrix problem.
- the principal eigenvector corresponds to a maximum eigenvalue.
- X(t) be transmitting signals in frequency domain for a BTS.
- IFFT Inverse discrete Fast Fourier Transform
- the method disclosed in the present invention creates a fixed speculative transformation matrix for a transmission/ reception system of an antenna array, generates an average covariance matrix of a receiving channel, and creates a covariance matrix of a transmitting channel by multiplying the average channel covariance matrix of the receiving channel with the fixed speculative transformation matrix.
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Radio Transmission System (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The present invention disclosed a method for obtaining a covariance matrix of a transmitting channel in a wireless network. The method comprises calculating a speculative transformation matrix, generating a covariance matrix of a receiving channel, and transforming the covariance matrix of the receiving channel into a covariance matrix of a transmitting channel using the speculative transformation matrix.
Description
METHOD FOR OBTAINING A COVARIANCE MATRIX OF A TRANSMITTING CHANNEL IN A WIRELESS NETWORK
CROSS REFERENCE
[0001] The present application claims the benefit of U.S. Provisional Application Serial 60/854,216, which was filed on October 24, 2006 and U.S. Patent Application 11/874,702 filed October 18, 2007.
BACKGROUND
[0002] In a wireless communications network employing a beamforming method, the quality of downlink signals received by a mobile station (MS) is determined by beamforming weighting vectors of a downlink channel. However, lack of information about channel coefficients of a downlink channel makes it difficult for a base transceiver station (BTS) in a frequency division duplex (FDD) network to obtain optimal beamforming weighting vectors for the downlink channel.
[0003] One way to address the issue is to develop a probing-and-feedback mechanism to obtain channel coefficients of a downlink channel. Employing a probing-and-feedback mechanism is not a preferred solution as it requires redesigning wireless communication protocols and incurs a large amount of overhead. In addition, a probing-and-feedback mechanism is only applicable to environments with slow fading channels.
[0004] Another way is to compute beamforming weighting vectors for a downlink channel by using a downlink channel covariance matrix that is transformed from an uplink channel covariance matrix. However, most of the
algorithms that transform an uplink channel covariance matrix into a downlink channel covariance matrix suffer from high computation complexity.
[0005] The issue described above is related to downlink and uplink channels in a communications network employing FDD. Nonetheless, it would be obvious for a person of skills in the art to know the above description is also applicable to other transmitting and receiving channels. As such, what is desired is a method and system for transforming a covariance matrix of a receiving channel into a covariance matrix of a transmitting channel.
SUMMARY
[0006] The present invention disclosed a method for transforming a covariance matrix of a receiving channel into a covariance matrix of a transmitting channel in a wireless network employing frequency division duplex. The method comprises calculating a speculative transformation matrix, generating a covariance matrix of a receiving channel, and transforming the covariance matrix of the receiving channel into a covariance matrix of a transmitting channel using the speculative transformation matrix.
[0007] The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0008] The drawings accompanying and forming part of this specification are included to depict certain aspects of the invention. The invention may be better
understood by reference to one or more of these drawings in combination with the description presented herein. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale.
[0009] FIG. 1 is a flow chart diagram illustrating a method in accordance with the present invention
DESCRIPTION
[0010] The following detailed description of the invention refers to the accompanying drawings. The description includes exemplary embodiments, not excluding other embodiments, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.
[0011] The present invention discloses a method that transforms a covariance matrix of a receiving channel into a covariance matrix of a transmitting channel in a wireless network employing frequency division duplex (FDD). Subsequently, the covariance matrix of the transmitting channel is used to compute beamforming weighting vectors of the transmitting channel.
[0012] The algorithm disclosed in the present invention improves the efficiency of computing beamforming weighting vectors in systems such as Macrocell/Microcell FDD OFDMA (Orthogonal Frequency Division Multiple Access). It performs well even when severe multi-path interference exists.
[0013] FIG. 1 is a flow chart diagram illustrating a method in accordance with the present invention. The method begins with step 110 of creating a speculative
transformation matrix without prior knowledge of the direction of arrival (DOA), θ . A speculative transformation matrix Cτ is determined by a predetermined number of system parameters such as the number of antennas, the spacing of antennas, the number of sectors, uplink and downlink carrier frequencies, etc. The speculative transformation matrix C1 is an M by M matrix (see step 110).
[0014] An array-steering vector A(θ, λ) , also known as an array response vector, is defined according to the arrangement of an antenna array. It is a function of the direction of arrival (DOA) of receiving signals, denoted as θ , and the wavelength of a wireless channel, denoted as λ . If the antenna array is a uniform linear array (ULA), which is arranged linearly, then A(θ,λ) is equal to
A(θ,λ) = [l
, where D is the distance between two adjacent antennas.
[0015] By contrast, if the antenna array is a uniform circular array (UCA), which is arranged circularly, then A{θ,λ) is equal to
-jψ∞s(θ) -jψ cos(θ-|f) -j^osφ JM-Jl lπ^
A(θ,λ) = [e λ e λ M • • • e *- M f , where r is the radius of a circular array.
[0016] A response matrix is represented by the following equation:
Q (θ) = A(θ,λ )ArL (θ,λ ) (1), where Q77 is a Hermitian operator. In a frequency
division duplex wireless network, the response matrix of a transmitting channel is denoted as Qtx[O) = A(Q ,λtχ)A (θ,λtχ) whereas the response matrix of a receiving
channel is denoted as Qn[O) = A(θ,λrx)AH (θ,λrx) .
[0017] Assuming that there are Nsector sectors in a cell, each sector is a pie shape. Each sector covers a region with a vertex angle of 2π/Nsector . In other words, it spans from angle ~π/Nsector to angle π/Nsector . Let φ equal π/Nsector .
[0018] A sector is further divided into Na partitions of the same size. Each partition has a vertex angle of Δ and Δ = 2φ /(N a - 1) . The transmitting and receiving response matrices of each partition are calculated according to equation 1. The DOA of the i-th partition, denoted as θ , equals (z - 1)Δ - φ . The cumulative transmitting and receiving response matrices are defined by the following equations respectively.
Thus, a speculative transformation matrix Cτ is given by Cj =
[0019] In step 120, channel coefficients of a receiving channel in frequency domain for a desired wireless station is estimated to be Hn = [H1^ 1 H1^ 2 ■■■ HnMf , where operator [*f represents vector transpose and M is a total number of antennas in a transmitting wireless station. Let Rn. be a covariance matrix of a receiving channel. The instantaneous covariance matrix of a receiving channel is computed according to the following equation: Rn. = Hn(Hn,)" . The average covariance matrix of the receiving channel is computed according to the following equation:
1 Ne
Rn. = — ∑ e Hi rx(Hi rx)H , where Ne is the number of samples and Ne is between [1,∞) .
[0020] In step 130, the covariance matrix R1x of a transmitting channel is transformed from the receiving covariance matrix Rn. according to the following equation: R1x = RrxCT .
[0021] In step 140, the covariance matrix of the transmitting channel is used to compute a transmitting beamforming weighting vector W1x by finding the principal eigenvector of a channel covariance matrix problem. The principal eigenvector corresponds to a maximum eigenvalue.
[0022] Let X(t) be transmitting signals in frequency domain for a BTS. Transmitting signals in time domain for an antenna array are computed according to the following equation: s(t) = ifft(wξx(t)) where ifft is the Inverse discrete Fast Fourier Transform (IFFT).
[0023] The method disclosed in the present invention creates a fixed speculative transformation matrix for a transmission/ reception system of an antenna array,
generates an average covariance matrix of a receiving channel, and creates a covariance matrix of a transmitting channel by multiplying the average channel covariance matrix of the receiving channel with the fixed speculative transformation matrix.
[0024] The above illustration provides many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims.
[0025] Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.
Claims
1. A method for obtaining a covariance matrix of a transmitting channel in a wireless network, the method comprising:
calculating a speculative transformation matrix from a receiving channel;
generating a covariance matrix of the receiving channel; and
transforming the covariance matrix of the receiving channel into a covariance matrix of a transmitting channel using the speculative transformation matrix.
2. The method of claim 1, wherein the calculating the speculative transformation matrix comprises:
generating a plurality of arrays of steering vectors of the transmitting channel;
computing a plurality of transmitting response matrices using the plurality of steering vectors of the transmitting channel;
generating a plurality of arrays of steering vectors of the receiving channel; and
computing a plurality of receiving response matrices using the plurality of steering vector of the receiving channel.
3. The method of claim 2, wherein the calculating the speculative transformation matrix further comprises: computing a cumulative transmitting response matrix using the plurality of transmitting response matrices of the transmitting channel; and
computing a cumulative receiving response matrix using the plurality of transmitting response matrices of the transmitting channel.
4. The method of claim 3, wherein the computing the cumulative transmitting 
Qfx(A -φ) response matrix ( Qtχ ) is based on the following equation: Qtχ = 
where i = [0,- ",N -1] ; Na is a total number of partitions in a cell; and Qtχ((i-l)A-φ) is a transmitting response matrix with a direction of arrival equal to 
5. The method of claim 3, wherein the computing the cumulative receiving
response matrix ( Qrx ) is based on the following equation: Qrx = 
where i = [0,- - -,Na -ϊ\ ; Na is a total number of partitions in a cell; and Qrx((i - 1)Δ - φ) is a receiving response matrix with a direction of arrival equal to 
6. The method of claim 3, wherein the calculating the speculative transformation matrix comprises a step of computing Cτ = (Q^ Qrx) \ Qn Qtx , where Cj is a speculative transformation matrix; Qtχ is a cumulative transmitting response matrix; Qrx is a cumulative receiving response matrix; and (.) is a Hermitian operator.
7. The method of claim 1, wherein the transforming the covariance matrix of the receiving channel into a covariance matrix of the transmitting channel is based on the following equation: R1x = RnC1, where, Cτ is a speculative transformation matrix; R1x is a covariance matrix of a transmitting channel; and Rn is a covariance matrix of a receiving channel.
8. A method for obtaining a covariance matrix of a transmitting channel in a wireless network, the method comprising:
calculating a speculative transformation matrix by generating a plurality of arrays of steering vectors of the transmitting channel, computing a plurality of transmitting response matrices, generating a plurality of arrays of steering vectors of a receiving channel, and computing a plurality of receiving response matrices;
generating a covariance matrix of a receiving channel; and
transforming the covariance matrix of the receiving channel into a covariance matrix of a transmitting channel using the following equation: R1x = RnC11 where, Cj is a speculative transformation matrix; R1x is a covariance matrix of a transmitting channel; and Rn is a covariance matrix of a receiving channel.
9. The method of claim 8, wherein the calculating the speculative transformation matrix comprises:
computing a cumulative transmitting response matrix using the plurality of transmitting response matrices of the transmitting channel; and computing a cumulative receiving response matrix using the plurality of transmitting response matrices of the transmitting channel.
10. The method of claim 9, wherein the computing the cumulative transmitting 
Qtx(A -φ) response matrix ( Qtχ ) is based on the following equation: Qtχ =
Qtx((Na -\)A -φ) where i = [0,- - -,Na -ϊ\ ; Na is a total number of partitions in a cell; and Qtχ((i-l)A-φ) is a transmitting response matrix with a direction of arrival equal to 
11. The method of claim 9, wherein the computing the cumulative receiving
response matrix ( Qrx ) is based on the following equation: Qrx 
where i = [0,- ",N -1] ; Na is a total number of partitions in a cell; and Qrx((i ~ I)A - φ) is a receiving response matrix with a direction of arrival equal to 
12. The method of claim 9, wherein the calculating the speculative transformation matrix comprises a step of computing Cj = (QrxQrx) Qrx Qtx> wnere Cj is a speculative transformation matrix; Qtχ is a cumulative transmitting response matrix; Qrx is a cumulative receiving response matrix; and (.) is a Hermitian operator.
13. A method for transforming a covariance matrix of a receiving channel into a covariance matrix of a transmitting channel in a wireless network employing frequency division duplex, the method comprising:
calculating a speculative transformation matrix from a receiving channel;
generating a covariance matrix of the receiving channel; and
transforming the covariance matrix of the receiving channel into a covariance matrix of a transmitting channel using the speculative transformation matrix.
14. The method of claim 13, wherein the calculating the speculative transformation matrix comprises:
generating a plurality of arrays of steering vectors of the transmitting channel;
computing a plurality of transmitting response matrices using the plurality of steering vectors of the transmitting channel;
generating a plurality of arrays of steering vectors of the receiving channel; and
computing a plurality of receiving response matrices using the plurality of steering vector of the receiving channel.
15. The method of claim 14, wherein the calculating the speculative transformation matrix further comprises:
computing a cumulative transmitting response matrix using the plurality of transmitting response matrices of the transmitting channel; and computing a cumulative receiving response matrix using the plurality of transmitting response matrices of the transmitting channel.
16. The method of claim 15, wherein the computing the cumulative transmitting 
Qtx(A -φ) response matrix ( Qtχ ) is based on the following equation: Qtχ =
Qtx((Na -\)A -φ) where i = [0,- - -,Na -ϊ\ ; Na is a total number of partitions in a cell; and Qtχ((i-l)A-φ) is a transmitting response matrix with a direction of arrival equal to 
17. The method of claim 15, wherein the computing the cumulative receiving
response matrix ( Qrx ) is based on the following equation: Qrx 
where i = [0,- ",N -1] ; Na is a total number of partitions in a cell; and Qrx((i ~ I)A - φ) is a receiving response matrix with a direction of arrival equal to 
18. The method of claim 15, wherein the calculating the speculative transformation matrix comprises a step of computing Cj = (QrxQrx) Qrx Qtx> where Cj is a speculative transformation matrix; Qtχ is a cumulative transmitting response matrix; Qrx is a cumulative receiving response matrix; and (.) is a Hermitian operator.
19. The method of claim 13, wherein the transforming the covariance matrix of the receiving channel into a covariance matrix of the transmitting channel is based on the following equation: R1x = RnC11 where, Cτ is a speculative transformation matrix; R1x is a covariance matrix of a transmitting channel; and Rn is a covariance matrix of a receiving channel.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60/854,216 | 2006-10-24 | ||
| US85421606P | 2006-10-25 | 2006-10-25 | |
| US11/874,702 US20080102768A1 (en) | 2006-10-25 | 2007-10-18 | Method for Obtaining a Covariance Matrix of a Transmitting Channel in a Wireless Network |
| US11/874,702 | 2007-10-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2008052010A2 true WO2008052010A2 (en) | 2008-05-02 |
| WO2008052010A8 WO2008052010A8 (en) | 2008-07-17 |
Family
ID=39325356
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US2007/082300 Ceased WO2008052010A2 (en) | 2006-10-24 | 2007-10-23 | Method for obtaining a covariance matrix of a transmitting channel in a wireless network |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US20080102768A1 (en) |
| WO (1) | WO2008052010A2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8243610B2 (en) * | 2009-04-21 | 2012-08-14 | Futurewei Technologies, Inc. | System and method for precoding codebook adaptation with low feedback overhead |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6018317A (en) * | 1995-06-02 | 2000-01-25 | Trw Inc. | Cochannel signal processing system |
| SE509278C2 (en) * | 1997-05-07 | 1999-01-11 | Ericsson Telefon Ab L M | Radio antenna device and method for simultaneous generation of wide lobe and narrow point lobe |
| AU2001234463A1 (en) * | 2000-01-14 | 2001-07-24 | Andrew Corporation | Repeaters for wireless communication systems |
| US7058145B2 (en) * | 2001-06-04 | 2006-06-06 | Qualcomm, Inc. | Diversity gain with a compact antenna |
| US6738020B1 (en) * | 2001-07-31 | 2004-05-18 | Arraycomm, Inc. | Estimation of downlink transmission parameters in a radio communications system with an adaptive antenna array |
| TW595857U (en) * | 2001-11-29 | 2004-06-21 | Us | 091219345 |
| JP4086574B2 (en) * | 2002-04-12 | 2008-05-14 | 松下電器産業株式会社 | Path search circuit, radio reception device, and radio transmission device |
| KR100689399B1 (en) * | 2002-05-17 | 2007-03-08 | 삼성전자주식회사 | Apparatus and method for forward transmission beam forming of smart antenna in mobile communication system |
| TWI289412B (en) * | 2003-05-16 | 2007-11-01 | Interdigital Tech Corp | Coordination of backhaul beam forming in wireless communication systems |
| US7313417B2 (en) * | 2003-12-19 | 2007-12-25 | Electronics And Telecommunications Research Institute | Transceiver for a base station with smart antenna and a switched beamforming method in downlink |
| US7630688B2 (en) * | 2004-03-31 | 2009-12-08 | Interdigital Technology Corporation | Mitigation of wireless transmit/receive unit (WTRU) to WTRU interference using multiple antennas or beams |
| US8180314B2 (en) * | 2006-03-08 | 2012-05-15 | Broadcom Corporation | Method and system for utilizing givens rotation to reduce feedback information overhead |
| WO2008103806A1 (en) * | 2007-02-22 | 2008-08-28 | Cisco Technology, Inc. | Method for generating downlink beamforming weighting vectors |
| US8059744B2 (en) * | 2008-04-25 | 2011-11-15 | Cisco Technology, Inc. | Frequency band extrapolation beamforming weight computation for wireless communications |
| US7825857B2 (en) * | 2009-02-09 | 2010-11-02 | Bae Systems Information And Electronic Systems Integration Inc. | System, method and apparatus for reducing the effects of low level interference in a communication system |
-
2007
- 2007-10-18 US US11/874,702 patent/US20080102768A1/en not_active Abandoned
- 2007-10-23 WO PCT/US2007/082300 patent/WO2008052010A2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| WO2008052010A8 (en) | 2008-07-17 |
| US20080102768A1 (en) | 2008-05-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20230097583A1 (en) | Apparatus and method for data communication based on intelligent reflecting surface in wireless communication system | |
| EP1344332B1 (en) | Method and apparatus for estimating downlink beamforming weights in a communications system | |
| US10734722B2 (en) | Beamforming method, apparatus for polarized antenna array and radio communication device and system thereof | |
| US9219535B2 (en) | Method for determining beamforming parameters in a wireless communication system and to a wireless communication system | |
| Zhang et al. | Intelligent omni surfaces assisted integrated multi-target sensing and multi-user MIMO communications | |
| US8134503B2 (en) | Open-loop beamforming MIMO communications in frequency division duplex systems | |
| Barriac et al. | Space-time communication for OFDM with implicit channel feedback | |
| US8032184B2 (en) | Method for generating downlink beamforming weighting vectors | |
| US20090080560A1 (en) | Closed-loop beamforming weight estimation in frequency division duplex systems | |
| US20070177681A1 (en) | Mimo-ofdm system using eigenbeamforming method | |
| US20090075616A1 (en) | Method and apparatus for determining an operating condition in a communications system | |
| Wang et al. | Low-complexity transceiver beamforming for DFRC with MIMO radar and MU-MIMO communication | |
| Huang et al. | Condition number improvement of IRS-aided near-field MIMO channels | |
| EP3763052B1 (en) | Channel covariance matrix conversion | |
| WO2008052010A2 (en) | Method for obtaining a covariance matrix of a transmitting channel in a wireless network | |
| KR100594816B1 (en) | MIO-OPEM System with Unique Beam Forming Technology | |
| Amadid et al. | Performance of massive mimo systems considering three dimensional array-based spatially correlated channel | |
| Lin et al. | Joint Beam and Power Allocation for Energy Efficient Capacity Enhancement in RIS-Assisted mmWave Networks | |
| Jeyakumar et al. | Large Antenna Array with Hybrid Beamforming System for 5G Indoor Communication Network Deployments | |
| Wang et al. | Oversampling based analog beamforming for initial access with a large number of receive antennas | |
| Tang et al. | Beam-Time Block Coding With Joint User Grouping and Beamforming for FDD Massive MIMO Systems | |
| Kanters et al. | Steerable Subarrays for Practical mmWave Massive MIMO: Algorithm Design and System-Level Analysis | |
| Nie et al. | VAMP-based channel estimation for wideband beamspace massive MIMO systems | |
| Cho et al. | Analog Beamforming Codebooks for Wideband Full-Duplex Millimeter-Wave Systems | |
| Yang et al. | Hybrid Precoding Towards Higher Frequency Systems |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 07854362 Country of ref document: EP Kind code of ref document: A2 |
|
| NENP | Non-entry into the national phase |
Ref country code: DE |
|
| 122 | Ep: pct application non-entry in european phase |
Ref document number: 07854362 Country of ref document: EP Kind code of ref document: A2 |