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US 7,925,303 B2Granted
Complementary beamforming methods and apparatuses
AssigneeXR Communications, LLC
InventorsVahid Tarokh, Yang-Seok Choi, Siavash Alamouti
Life of this patent
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Abstract
Improved methods and apparatuses are provided to address a potential “hidden beam problem” in wireless communication systems employing smart antennas. The improved methods and apparatuses utilize complementary beamforming (CBF) techniques, such as, for example, Subspace Complementary Beamforming (SCBF), Complementary Superposition Beamforming (CSBF) and/or Single Beam Complementary Beamforming (SBCBF) techniques.
Claims48
A method, comprising:
- determining at least one signal operatively configured for subspace complementary beamforming (SCBF) in a wireless communication system;
- generating the at least one signal such that the signal is operatively configured to cause a smart antenna to perform said SCBF and transmit at least one complementary beam;
- and
- determining the at least one signal using a Steering Matrix:
- A=[a(θ1) a(θ2) . . . a(θk)], wherein a(θk) represents a steering vector of user k;
- wherein:
- if W=A*B, where B is a non-singular K-by-K matrix, then using a complementary beamforming matrix of
- W
- c
- =
- k
- 0
-
- C
- 0
- N
-
- [
- u
- K
- +
- 1
- u
- K
- +
- 2
- …
- u
- N
- ]
- wherein C0=Nc0 is the level of the main lobe, k0 is the scaling factor and ul is the l-th column vector of U;
- otherwise using a complementary beamforming matrix of
- W
- c
- =
- k
- 0
-
- C
- 0
- N
-
- [
- u
- _
- 1
- u
- _
- 2
- …
- u
- _
- N
- -
- K
- ]
- wherein ū1 is the l-th left singular vector of the matrix
- (
- ∑
- l
- =
- K
- +
- 1
- N
-
- u
- ~
- 1
-
- u
- ~
- 1
- H
- )
-
- U
-
-
- Λ
- c
- =
- U
-
-
- Λ
- _
-
- V
- _
- H
- ,
- where A*=Ũ{tilde over (Λ)}{tilde over (V)}H is assumed and a scattering channel
- H*=Ũ{tilde over (Λ)}{tilde over (V)}H is assumed.
91 more elements
A method, comprising:
- determining at least one signal operatively configured for complementary superposition beamforming (CSBF) in a wireless communication system;
- generating the at least one signal such that the signal is operatively configured to cause a smart antenna to perform said CSBF and to transmit at least one complementary beam, and
- determining the at least one signal using a downlink beamforming matrix:
- {tilde over (W)}=└w1 . . . wk−1 {tilde over (w)}k wk+1 . . . wk┘, where {tilde over (w)}k=p0wk+Wcp and p is complex conjugate transpose of the l-th row of Wc,
- p
- 0
- =
- w
- k
- ,
- l
- *
-
- w
- k
- ,
- l
-
- is normalized complex conjugate of the l-th element of wk,
- where Wc=√{square root over (c0[uK+1, uK+2, . . . uN])},
- C0 is a scalar, K=the number of users, N=the number of antennas and ul is the l-th vector of U.
18 more elements
A method, comprising:
- determining at least one signal operatively configured for complementary superposition beamforming (CSBF) in a wireless communication system;
- generating the at least one signal such that the signal is operatively configured to cause a smart antenna to perform said CSBF and to transmit at least one complementary beam, and
- determining the at least one signal using:
- {tilde over (W)}=[w1 w2 . . . wk Wcp]
- wherein:
- p is complex conjugate transpose of the l-th row of Wc,
- Wc=√{square root over (c0[uK+1, uK+2, . . . , uN])},
- c0 is a scalar, K=the number of users, N=the number of antennas and ul is the l-th column vector of U.
5 more elements
A method, comprising:
- determining at least one signal operatively configured for complementary superposition beamforming (CSBF) in a wireless communication system;
- generating the at least one signal such that the signal is operatively configured to cause a smart antenna to perform said CSBF and to transmit at least one complementary beam, and
- determining the at least one signal using a downlink beamforming matrix:
- {tilde over (W)}=└w1 . . . wk−1 {tilde over (w)}k wk+1 . . . wk┘, where {tilde over (w)}k=p0wk+Wcp and p is complex conjugate transpose of the l-th row of Wc,
- p
- 0
- =
- w
- k
- ,
- l
- *
-
- w
- k
- ,
- l
-
- is normalized complex conjugate of the l-th element of wk,
- where Wc=√{square root over (c0[ua,r+1, ua,r+2, . . . , ua,N])},
- c0 is a scalar, K=the number of users, N=the number of antennas, r=rank of W and is in the range of K to 2K and ua,l is the l-th left singular vector whose corresponding singular value is zero.
18 more elements
A method, comprising:
- determining at least one signal operatively configured for complementary superposition beamforming (CSBF) in a wireless communication system;
- generating the at least one signal such that the signal is operatively configured to cause a smart antenna to perform said CSBF and to transmit at least one complementary beam, and
- determining the at least one signal using:
- {tilde over (W)}=[w1 w2 . . . wk Wcp]
- wherein:
- p is complex conjugate transpose of the l-th row of Wc,
- Wc=√{square root over (c0[ua,r+1, ea,r+2, . . . , ua,N])},
- c0 is a scalar, K=the number of users, N=the number of antennas, r=rank of W and is in the range of K to 2K and ua,l is the l-th left singular vector whose corresponding singular value is zero.
5 more elements
Dependencies are inferred from the claim text.