Communications: directive radio wave systems and devices (e.g. – Directive – Including a steerable array
Reexamination Certificate
2000-06-23
2001-04-17
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a steerable array
Reexamination Certificate
active
06218986
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an adaptive diversity apparatus for digital communication.
2. Description of the Related Art
A conventional adaptive diversity apparatus will be described with reference to FIG.
1
and FIG.
2
.
FIG. 1
is a block diagram of the conventional adaptive diversity apparatus.
FIG. 2
is a radiation pattern view of assistance in explaining reception (transmission) radiation pattern. In
FIG. 1
, complex signals which are received by reception antennas
1
,
2
,
3
and
4
at a time t, A/D converted and quasi-coherent detected complex signals are designated S
1
(t), S
2
(t), S
3
(t) and S
4
(t), respectively.
A reception radiation pattern controller
9
transmits complex weights W
1
(t), W
2
(t), W
3
(t) and W
4
(t) to multipliers
5
,
6
,
7
and
8
. The multipliers
5
,
6
,
7
and
8
multiply the abovementioned complex signals by the complex weights. The multiplied complex signals are added by an adder
12
. At this time, when the output of the reception radiation pattern controller
9
is S(t), the output S(t) can be expressed as the following formula (1):
S
(
t
)=&Sgr;
1
4
W
i
(
t
)
S
i
(
t
) (1)
By thus composing the reception signals from a plurality of antennas after multiplying them by appropriate complex numbers, it is possible to provide all the antennas with radiation pattern on a plane as shown in FIG.
2
. For example, in
FIG. 2
, when a desired signal is coming from the direction of the arrow
21
and an interference signal is coming from the direction of the arrow
22
, the reception radiation pattern controller
9
controls the radiation pattern as shown at the reference numeral
23
of FIG.
2
. That is, the controller
9
controls the radiation pattern so that the desired signal is received with high intensity and the interference signal is received with low intensity. Thereby, the reception performance can be improved.
A decider
11
outputs the result D(t) of hard decision of the composite signal S(t). An error detector
10
outputs the difference S(t)−D(t) between the composite signal S(t) and the detected result D(t). The reception radiation pattern controller
9
updates its output complex weights W
1
(t), W
2
(t), W
3
(t) and W
4
(t) based on the output of the error detector and S
1
(t), S
2
(t), S
3
(t) and S
4
(1).
For example, when the reception signal vector is expressed as Sig(t)=(S
1
(t), S
2
(t), S
3
(t), S
4
(t))
T
and the output of the reception radiation pattern controller, as W(t)=(W
1
(t), W
2
(t), W
3
(t), W
4
(t))
T
, the updated complex weights can be expressed as the following formula (2):
W
(
t+
1)=
W
(
t
)+&mgr;(
S
(
t
)−
D
(
t
))
T
Sig
(
t
) (2)
Here, &mgr; is a step factor.
In the above-described conventional adaptive diversity apparatus, by successively updating the weights which are multiplied by the input signals from the antennas, even when the transmitting side moves, the radiation pattern can be formed in accordance with the movement.
In the conventional apparatus, when the movement speed of the transmitting side is low, the radiation pattern can be formed in accordance with the movement; however, when the movement speed of the transmitting side is high, since the complex weights do not converge, the processing by the reception radiation pattern controller cannot respond to the movement, so that a correct radiation pattern cannot be formed.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an adaptive diversity apparatus in which the transmission and reception performance is improved by causing a reception radiation pattern controller or a transmission radiation pattern controller to respond to the movement of a transmitting side or a receiving side to thereby form a correct radiation pattern even when the movement speed of the transmitting side or the receiving side is high.
To solve the abovementioned problem, according to the present invention, by estimating the movement direction of a communication partner, the radiation pattern is forcibly rotated to thereby form a correct radiation pattern.
Specifically, an adaptive diversity apparatus of the present invention comprises: reception radiation pattern control means for providing a reception signal from an antenna with a first reception radiation pattern by a first control signal; radiation pattern control means for providing the reception signal with a second reception radiation pattern by a second control signal based on an output of movement direction estimating means for estimating a movement direction of a transmitting side; and a reception signal processing system having multiplication means for multiplying the abovementioned reception signal by the abovementioned first control signal and the second control signal.
According to this feature, since the reception radiation pattern extracted and generated from the reception signal can be corrected at high speed in accordance with the movement of the transmitting side, the reception performance can be significantly improved.
Moreover, in the adaptive diversity apparatus of the present invention, the radiation pattern control means outputs the second control signal for controlling rotation of the first reception radiation pattern based on the output of the movement direction estimating means. According to this feature, by rotating the phase of the first reception radiation pattern, the reception radiation pattern can be surely and easily corrected.
Moreover, in the adaptive diversity apparatus of the present invention, the radiation pattern control means generates the second control signal so as to cancel a phase variation obtained by displacement of a direction of arrival. According to this feature, since a relative angle from a communication partner can be calculated by estimating from the reception signal the direction of arrival, radiation pattern control can be realized at a low cost.
Moreover, in the adaptive diversity apparatus of the present invention, the reception radiation pattern control means and the radiation pattern control means are provided independently of each other, and the reception signal, the first control signal and the second control signal are multiplied by single multiplication means. Thereby, the circuit is simplified, so that incorporation or mounting of the radiation pattern control means into an existing circuit is facilitated.
Moreover, in a case where the present invention is applied to an adaptive reception diversity apparatus, specifically, an arrangement is employed comprising: a plurality of antennas; movement direction estimating means for estimating a movement direction of a transmitting side; reception radiation pattern control means for providing reception signals from the antennas with reception radiation pattern; addition means for composing a plurality of inputs from the abovementioned antennas; radiation pattern control means for controlling rotation of the abovementioned reception radiation pattern based on an output of the abovementioned movement direction estimating means; decision means for performing hard decision of an output of the abovementioned addition means; and error detecting means for detecting an error between an output of the decision means and the output of the abovementioned addition means, to feed back the error to the abovementioned reception radiation pattern control means.
Moreover, in the adaptive diversity apparatus of the present invention, the radiation pattern correction control means obtains a relative phase variation due to a movement of the transmitting side at each of the plurality of disposed antennas based on the output of the movement direction estimating means, and generates the second control signal in accordance with each phase variation. Moreover, in the adaptive diversity apparatus of the present invention, the radiation pattern control means obtains a relative phase variation due to a movement of the receiving side at each of the plurality of disposed anten
Hiramatsu Katsuhiko
Yukitomo Hideki
Greenblum & Bernstein P.L.C.
Matsushita Electric - Industrial Co., Ltd.
Mull Fred H
Tarcza Thomas H.
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