System and method for efficient antenna weight vector tables within phased-array antennas
Method and system are provided for reducing the AWV table size for phased-array antenna. In one novel aspect, the AWV table is decomposed to a combination of a first AWV table and a second AWV table, with a combined size smaller than the size of the AWV table. In one novel aspect, a group of decomposable AWVs are identified and each decomposed into a decomposed first AWVs and a decomposed second AWVs. In one embodiment, the decomposable weights W that are decomposed into W h being a function of both elevation θ and azimuth φ and W v being a function of elevation θ only. In one novel aspect, the AWV table for a phased-array antenna with N antenna elements with M v weights in a vertical direction and M h weights in a horizontal direction is decomposed into a first AWV table and a second AWV table with a combined size of N*(M v +M h ).
1 . A method, for reducing a size of an antenna weight vector (AWV) table of each corresponding antenna element of a phased-array antenna, comprising:
decomposing a decomposable group AWVs for each antenna element into a first decomposed AWVs and a second decomposed AWVs, wherein the decomposable group of AWVs is a product of the first decomposed AWVs and the second decomposed AWVs; and
generating and storing a first AWV table and a second AWV table as the AWV table for each antenna element of the phased-array antenna, wherein the first AWV table includes the first decomposed AWVs and non-decomposed AWVs, and the second AWV table includes the second decomposed AWVs and non-decomposed AWVs.
2 . The method of claim 1 , wherein the decomposable AWVs have weights W that are decomposed into W h and W v , and wherein W v is a function of elevation θ only and W h is a function of both elevation θ and azimuth φ.
3 . The method of claim 2 , wherein the first AWV table and the second AWV table further include corresponding null weight W null with zero phase shift and an amplitude equals to 1.
4 . The method of claim 1 , further comprising:
determining a decomposable elevation;
determining a decomposable angle θ based on the decomposable elevation;
forming the decomposable group of AWVs based on the decomposable angle θ.
5 . The method of claim 4 , wherein the decomposable angle θ is close to 90°.
6 . The method of claim 1 , wherein each AWV comprises at least phase shifter settings and amplitude gain settings.
7 . The method of claim 6 , wherein the decomposing applies to both an amplitude adjustment and a phase adjustment.
8 . The method of claim 1 , wherein the first AWV table further includes an active elevation beam index and the second AWV table further includes an active azimuth beam index.
9 . The method of claim 8 , wherein the active elevation beam index is indicated by an elevation pointer and the active azimuth beam index is indicated by an azimuth pointer for the beamforming control.
10 . The method of claim 1 , further comprising:
performing a beamforming control based on the first AWV table and the second AWV table the phased-array antenna, and wherein the beamforming control is performed by combining the first AWV table and the second AWV table for the beamforming control.
11 . The method of claim 10 , wherein phase shift values in the first AWV table and the second AWV table are combined with modulo 360-degree.
12 . The method of claim 11 , wherein delay values are added for the first AWV table and the second AWV table when performing broadband phased-array operations.
13 . The method of claim 10 , wherein a composite gain value is a sum of gain adjustment values in the first AWV table and the second AWV table.
14 . The method of claim 13 , wherein a gain adjustment exceeds a single stage amplifier range, a residual value is passed to a second amplifier for more gain adjustment.
15 . A system with reduced size of antenna weight vector (AWV) tables, comprising:
a plurality of N h *N v antenna elements for a phased-array antenna with a size of Nv by Nh in a uniform planar structure, each includes a frontend processing unit, a digital controller;
a signal combiner; and
a control and synchronization bus,
wherein the digital control of each antenna element has a corresponding AWV table for M v weights in a vertical direction and M h weights in a horizontal direction, and wherein the AWV table is decomposed to a combination of a first AWV table and a second AWV table, and wherein a size of a sum of a size of the first AWV table and a size of the second AWV table is smaller than N h *N v *M h *M v .
16 . The system of claim 15 , a group of decomposable AWVs are identified and each decomposed into a decomposed first AWVs and a decomposed second AWVs, and the first AWV table includes the of decomposed first AWVs and non-decomposed AWVs, and the second AWV table includes the decomposed second AWVs and non-decomposed AWVs.
17 . The system of claim 16 , wherein the decomposable AWVs have weights W that are decomposed into W h and W v , and wherein W v is a function of elevation θ only and W h is a function of both elevation θ and azimuth φ.
18 . The system of claim 15 , wherein the AWV table for each antenna element of the phased-array antenna has a size of N v *N h *(M v +M h ).
19 . The system of claim 18 , wherein an element (m, n) of the second AWV table is computed using
W
h
9
0
(
φ
0
′
)
=
e
-
j
2
π
(
n
d
h
-
0
h
)
sin
(
π
/
2
)
sin
(
φ
0
′
)
/
λ
*
e
-
j
2
π
(
m
d
v
-
0
v
)
cos
(
π
/
2
)
sin
(
φ
0
′
)
/
λ
,
and an element (m, n) of the first AWV table is computed using
W
v
0
(
θ
0
)
=
e
-
j
2
π
(
n
d
h
-
0
h
)
sin
(
θ
0
)
sin
(
0
)
/
λ
*
e
-
j
2
π
(
m
d
v
-
0
v
)
cos
(
θ
0
)
/
λ
,
wherein λ is a wavelength, d v is vertical spacing for antenna elements, d h is horizontal spacing for antenna elements, and O v =−(N v +1)/2*d v , O h =−(N h +1)/2*d h .
20 . The system of claim 19 , wherein φ 0 ′ is computed using
φ
0
′
=
sin
-
1
(
sin
(
θ
0
)
sin
(
φ
0
)
)
.