Method for operating a MIMO radar
In a method for operating a MIMO radar, an influence of an object motion on an angle estimate is substantially eliminated, and a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar is identified by optimizing the following mathematical relationship: d _ pulses , opt = arg max d _ pulses [ Var S ( d _ pulses ) - ( Cov S ( d _ pulses , t ) ) 2 / Var S ( t _ ) ] in which: d pulses,opt is optimized positions of the transmitters in the sequence in which they transmit; d pulses is positions of the transmitters in the sequence in which they transmit; t is transmission instants; Var S is sample variance; and Cov S is sample covariance.
1. A method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
identifying a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar by optimizing the following mathematical relationship:
d
_
pulses
,
opt
=
arg
max
[
Var
S
(
d
_
pulses
)
-
(
Cov
S
(
d
_
pulses
,
t
)
)
2
/
Var
S
(
t
_
)
]
d
_
pulses
wherein:
d pulses,opt is optimized positions of the transmitters in a sequence in which the transmitters transmit;
d pulses is positions of the transmitters in a sequence in which the transmitters transmit;
t is transmission instants;
Var S is sample variance; and
Cov S is sample covariance.
2. A method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
identifying a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar by optimizing the following mathematical relationships:
|Cov WS ( d pulses,x ,t ,ρ)|=minimal
|Cov WS ( d pulses,y ,t ,ρ)|=minimal
wherein:
d pulses,x is X positions of the transmitters in a sequence in which the transmitters transmit;
d pulses,y is Y positions of the transmitters in the sequence in which the transmitters transmit;
t is transmission instants;
ρ is transmission energies;
Cov WS is weighted sample covariance, wherein
Cov
WS
(
x
_
,
y
_
,
w
_
)
:=
E
WS
(
[
x
_
-
E
WS
(
x
_
,
w
_
)
·
1
_
]
⊗
[
y
_
-
E
WS
(
y
_
,
w
_
)
·
1
_
]
,
w
_
)
E
WS
(
x
_
,
w
_
)
:=
1
∑
j
=
1
K
wj
∑
i
=
1
K
xi
·
wi
wherein:
w is weight vector;
EWS is weighted sample mean; and
is element-wise multiplication.
3. The method as recited in claim 2 , wherein an optimization of the following mathematical relationships is carried out:
Cov WS ( d pulses,x ,t ,ρ)=0
Cov WS ( d pulses,y ,t ,ρ)=0.
4. A method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
providing at least two transmitters having different activation time frames; and
activating the transmitters a different number of times in the respective activation time frames of the transmitters such that a common center instant for the transmitters is provided for the activation time frames of the transmitters.
5. The method as recited in claim 4 , wherein one of the transmitters is activated with a time offset from a second one of the transmitters, the respectively later-activated transmitter being activated, in a boundary region of the respective activation time frame, at least one less time than the other transmitter, the other transmitter being not activated the same number of times at the beginning and at the end of the respective activation time frame.
6. The method as recited in claim 5 , wherein a discrete Fourier transform is carried out for signal evaluation, and wherein sampled values of the later-activated transmitter are made up by way of zero paddings to the number of sampled values of the other transmitter, and wherein by using an amplitude factor, (i) a phase difference in the sampled signals of the two transmitters is corrected, and (ii) the sampled signals of the two transmitters are equalized.
7. The method as recited in claim 6 , wherein a transmission-ramp-based radar modulation is used for the signals of the transmitters.
8. The method as recited in claim 1 , wherein the MIMO radar is situated in a motor vehicle, and wherein the method is used to identify at least one of the following variables: distance, relative velocity, and angle.
9. A non-transitory computer-readable data storage medium storing a computer program having program codes which, when executed on a computer, performs a method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
identifying a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar by optimizing the following mathematical relationship:
d
_
pulses
,
opt
=
arg
max
[
Var
S
(
d
_
pulses
)
-
(
Cov
S
(
d
_
pulses
,
t
)
)
2
/
Var
S
(
t
_
)
]
d
_
pulses
wherein:
d pulses,opt is optimized positions of the transmitters in a sequence in which the transmitters transmit;
d pulses is positions of the transmitters in a sequence in which the transmitters transmit;
t is transmission instants;
Var S is sample variance; and
Cov S is sample covariance.