Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems
Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.
1. A method, comprising:
forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from a received orthogonal frequency division multiplexed (OFDM) symbol;
forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B;
multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q); and
determining a beam identifier from the P and Q matrices.
2. The method of claim 1 , further comprising receiving the OFDM symbol at a plurality of antennas (N) that are weighted to form the selected beam pattern.
3. The method of claim 1 , further comprising receiving the OFDM symbol in a sub-frame of OFDM symbols.
4. The method of claim 1 , wherein the operation of forming the summation matrix S comprises forming the summation matrix according to S=A+B.
5. The method of claim 1 , wherein the operation of forming the difference matrix D comprises forming the difference matrix according to D=A−B.
6. The method of claim 1 , wherein the operation of multiplying the beamformer preset matrix W comprises;
generating the matrix P according to P=W H S; and
generating the matrix Q according to Q=W H D.
7. The method of claim 6 , wherein the operation of determining the beam identifier comprises determining a beamformer present (m) out of the M available presets according to the following:
arg
m
∈
M
max
∑
l
=
1
L
CP
w
m
H
s
l
2
w
m
H
d
l
2
=
arg
m
∈
M
max
∑
l
=
1
L
CP
p
m
,
l
2
q
m
,
l
2
.
8. The method of claim 1 , further comprising performing the method to determine the beam identifier based on symbols in each received sub-frame.
9. An apparatus, comprising:
a first matrix forming circuit that forms a matrix (A) of cyclic prefix values from a received orthogonal frequency division multiplexed (OFDM) symbol;
a second matrix forming circuit that forms a matrix (B) of tail values from the received orthogonal frequency division multiplexed (OFDM) symbol;
a summation circuit that forms a summation matrix (S) from the matrix A and the matrix B;
a difference circuit that forms a difference matrix (D) from the matrix A and the matrix B;
a multiplying circuit that multiplies a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q); and
a determination circuit that determines a beam identifier from the P and Q matrices.
10. The apparatus of claim 9 , further comprising a symbol receiving circuit that receives the OFDM symbol at a plurality of antennas (N) that are weighted to form the selected beam pattern.
11. The apparatus of claim 9 , wherein the symbol receiving circuit receives the OFDM symbol in a sub-frame of OFDM symbols.
12. The apparatus of claim 9 , wherein the summation circuit forms the summation matrix S according to S=A+B.
13. The apparatus of claim 9 , wherein the difference circuit forms the difference matrix D according to D=A−B.
14. The apparatus of claim 9 , wherein the multiplying circuit operates to:
generate the matrix P according to P=W H S; and
generate the matrix Q according to Q=W H D.
15. The apparatus of claim 14 , wherein the determination circuit determines a beamformer present (m) out of the M available presets according to the following:
arg
m
∈
M
max
∑
l
=
1
L
CP
w
m
H
s
l
2
w
m
H
d
l
2
=
arg
m
∈
M
max
∑
l
=
1
L
CP
p
m
,
l
2
q
m
,
l
2
.
16. The apparatus of claim 9 , wherein the beam identifier is determined based on symbols in each received sub-frame.
17. An apparatus, comprising:
means for forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from a received orthogonal frequency division multiplexed (OFDM) symbol;
means for forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B;
means for multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q); and
means for determining a beam identifier from the P and Q matrices.
18. The apparatus of claim 17 , wherein the means for forming the summation matrix S comprises means for forming the summation matrix according to S=A+B, and the means for forming the difference matrix D comprises means for forming the difference matrix according to D=A−B.
19. The apparatus of claim 17 , wherein the means for multiplying the beamformer preset matrix W comprises;
means for generating the matrix P according to P=W H S; and
means for generating the matrix Q according to Q=W H D.
20. The apparatus of claim 19 , wherein the means for determining the beam identifier comprises means for determining a beamformer present (m) out of the M available presets according to the following:
arg
m
∈
M
max
∑
l
=
1
L
CP
w
m
H
s
l
2
w
m
H
d
l
2
=
arg
m
∈
M
max
∑
l
=
1
L
CP
p
m
,
l
2
q
m
,
l
2
.