US 7,248,897 B2Granted

Method of optimizing radiation pattern of smart antenna

OwnerChao-Hsing Hsuinventor

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Abstract

In this invention, the formulas of optimizing radiation pattern of the smart antenna have been deduced and a set of weights, including amplitude and phase shift weight or only phase shift weights, for optimal channel assignment is generated using optimization techniques (e.g., advance algorithms) for smart antennas. These algorithms can deal with the Spatial Division Multiple Access (SDMA) to enlarge the capacity of communication systems and maximize the main lobes toward the users as well as minimize the pattern nulling toward the interfering sources by iterating both the amplitude weights and phase shift weights or the phase shift weight only of a cost function. Thus, an optimal radiation pattern could be derived based on the output power of the cost function with iterated amplitude and phase shift weights or only phase shift weights. At the same time, SDMA of smart antennas can be come true.

Claims14

Dependent claims

A method for optimizing a radiation pattern of a smart antenna including a linear array of antenna elements, comprising the steps of:

determining directions of a desired signal and interfering signals;
adjusting amplitude weights and phase shift weights of the antenna elements by a cost function until the cost function in the direction of the desired signal is maximized and the cost function in the direction of each interfering signal is minimized;
and
obtaining the optimized radiation pattern by the cost function with the adjusted amplitude weights and phase shift weights;
wherein the cost function is represented by AFm(θ):
A
⁢
⁢
F
m
⁡
(
θ
)
=
2
*
1
M
⁢
∑
n
=
1
N
⁢
α
m
⁢
⁢
n
⁢
cos
⁡
[
(
n
-
0.5
)
⁢
ψ
+
β
m
⁢
⁢
n
]
,
m
=
1
,
2
,
3
,
⁢
…
⁢
,
M
where M is the number of users;
AFm(θ) is the cost function of the linear array for a receiver m;
2N is the number of antenna elements;
n=1,2,3, . . . , N;
αmn is the amplitude weight of antenna element n for the receiver m;
βmn is the phase shift weight of antenna element n for the receiver m;
θ is an angle between an incident signal and an array normal;
and
Ψ=kd sin θ, k is a Boltzmann constant, d is a distance of two adjacent antenna elements.

69 more elements

Dependencies are inferred from the claim text.