Method and system for estimating the location of a mobile terminal
A method and system are provided for estimating the location of a mobile radio-communication terminal, the mobile terminal having a plurality of antennas, and being in communication range of at least one transmitter having a plurality of antennas, the method comprising; measuring the time of arrival of a signal transmitted from the M antennas of the at least one transmitter at each of the N antennas of the mobile terminal to determine M×N range measurements corresponding to the M×N transmission paths of said signal between the M antennas of the transmitter and the N antennas of the mobile terminal; and estimating the location of the mobile terminal based on the M×N range measurements. The location of the mobile terminal may be estimated by applying a least squares method.
1. A method of estimating the location of a mobile terminal, the mobile terminal being in communication range of a transmitter, at least one of the transmitter and the mobile terminal having a plurality of antennas, the method comprising:
determining the time of arrival of a signal transmitted from M antenna(s) of the transmitter at each of N antenna(s) of the mobile terminal to provide M×N range measurements corresponding to the M×N transmission paths of said signal between the M antenna(s) of the transmitter and the N antenna(s) of the mobile terminal; and
estimating, using a least square method, the location of the mobile terminal based on the M×N range measurements, and a predetermined location of the transmitter, where M and or N ≧2, and
wherein the location of the mobile terminal is estimated by minimizing through J×K×M×N terms, the least squares expression:
e
LS
=
∑
j
=
1
J
∑
k
=
1
K
∑
m
=
1
M
∑
n
=
1
N
d
jk
mn
-
d
jk
(
x
^
,
y
^
)
2
where:
d jk mn is the range measurement obtained for each signal transmission path where
j represents the transmitter number (1 to J )of J transmitters
k represents the transmitted signal (1 to K) of K transmitted signals of the j-th transmitter,
m represents the transmitting antenna number (1 to M) of the j-th transmitter provided with M antennas, and
n represents the receiving antenna number (1 to N) of the mobile terminal provided with N antennas, and
d kj ({circumflex over (x)},ŷ) is the calculated range derived from ∥x−X∥, where x are the estimated co-ordinates [x,y] T of mobile terminal and X are the known co-ordinates [X j ,Y j ] T of the j-th transmitter, where J≧1 and K≧1.
2. The method according to claim 1 , wherein the time of arrival of the signal at each of the N antennas of the mobile terminal is measured by detecting the first arrival path in the respective response of the respective receiving antenna to a spread spectrum signal of the transmitted signal.
3. A location estimation module for estimating the location of a mobile terminal having a plurality N of antennas, the module comprising:
a detector for detecting the time of arrival of a signal transmitted from M antennas of at least one transmitter at each of the N antennas of the receiver to provide M×N range measurements corresponding to the M×N transmission paths of said signal between the M antenna(e) of the transmitter and the N antennas of the mobile terminal; and
a processor for estimating, using a least square method, the location of the mobile terminal based on the M×N range measurements and the location of the at least one transmitter,
wherein the processor is operable to estimate the location of the mobile terminal by minimizing through J×K×M×N terms, the expression:
e
LS
=
∑
j
=
1
J
∑
k
=
1
K
∑
m
=
1
M
∑
n
=
1
N
d
jk
mn
-
d
jk
(
x
^
,
y
^
)
2
where:
d jk mn is the range measurement obtained for each signal transmission path where
j represents the transmitter number (1 to J) of J transmitters
k represents the transmitted signal (1 to K) of K transmitted signals of the j-th transmitter,
m represents the transmitting antenna number (1 to M) of the j-th transmitter provided with M antennas, and
n represents the receiving antenna number (1 to N) of the mobile terminal provided with N antennas, and
d kj ({circumflex over (x)},ŷ) is the calculated range derived from ∥x−X∥, where x are the estimated co-ordinates [x,y] T of mobile terminal and X are the known co-ordinates [X j ,Y j ] T of base station j, where J≧1 and K≧1.
4. The location estimation module according to claim 3 wherein the detector is operable to measure the time of arrival of the signal at each of the N antennas of the mobile terminal by detecting the first arrival path in the respective response of the respective receiving antenna to a spread spectrum signal of the transmitted signal.
5. A mobile telecommunication terminal comprising:
a plurality of antennas for receiving a radio signal from a transmitter; and
the location estimation module according to claim 3 for estimating the location of the mobile terminal.
6. A non-transitory computer-readable medium having computer-executable instructions to enable a computer system to perform the method of claim 1 .
7. A method of estimating the location of a mobile terminal, the mobile terminal being in communication range of a transmitter, at least one of the transmitter and the mobile terminal having a plurality of antennas, the method comprising:
determining the time of arrival of a signal transmitted from M antenna(s) of the transmitter at each of N antenna(s) of the mobile terminal to provide M×N range measurements corresponding to the MXN transmission paths of said signal between the M antenna(s) of the transmitter and the N antenna(s) of the mobile terminal; and
estimating, using a least square method, the location of the mobile terminal based on the M×N range measurements, and a predetermined location of the transmitter, where M and/or N ≧2, and
wherein the location of the mobile terminal is estimated by minimizing through J×K terms, the expression:
e
LS
=
∑
j
=
1
J
∑
k
=
1
K
d
~
jk
-
d
jk
(
x
^
,
y
^
)
2
where
:
d
~
jk
=
1
MN
∑
m
=
1
M
∑
n
=
1
N
d
jk
mn
d jk mn is the range measurement obtained for each signal transmission path where
j represents the transmitter number (1 to J) of J transmitters,
k represents the transmitted signal (1 to K) of K transmissions for the j-th transmitter,
m represents the transmitting antenna number (1 to M) of the j-th transmitter provided with M antennas, and
n represents the receiving antenna number (1 to N) of the mobile terminal provided with N antennas, and
d kj ({circumflex over (x)},ŷ) is the calculated range derived from ∥x−X∥, where x are the estimated co-ordinates [x,y] T of mobile terminal and X are the known co-ordinates [X j ,Y j ] T of the j-th transmitter, where J≧1 and K≧1.
8. A method of estimating the location of a mobile terminal, the mobile terminal being in communication range of a transmitter, at least one of the transmitter and the mobile terminal having a plurality of antennas, the method comprising:
determining the time of arrival of a signal transmitted from M antenna(s) of the transmitter at each of N antenna(s) of the mobile terminal to provide M×N range measurements corresponding to the MXN transmission paths of said signal between the M antenna(s) of the transmitter and the N antenna(s) of the mobile terminal; and
estimating, using a least square method, the location of the mobile terminal based on the M×N range measurements, and a predetermined location of the transmitter, where M and or N ≧2,
wherein the location of the mobile terminal is estimated by minimizing through J×K terms, the expression:
e
LS
=
∑
j
=
1
J
∑
k
=
1
K
d
~
jk
-
d
jk
(
x
^
,
y
^
)
2
where
:
d
~
jk
=
min
jk
(
d
jk
11
,
…
,
d
jk
mn
,
…
,
d
JK
MN
)
d jk mn is the range measurement obtained for each signal transmission path where
j represents the transmitter number (1 to J) of J transmitters,
k represents the transmitted signal (1 to K) for the j-th transmitter,
m represents the transmitting antenna number (1 to M) of the j-th transmitter provided with M antennas, and
n represents the receiving antenna number (1 to N) of the mobile terminal provided with N antennas, and
d kj ({circumflex over (x)},ŷ) is the calculated range derived from ∥x−X∥, where x are the estimated co-ordinates [x,y] T of mobile terminal and X are the known co-ordinates [X j ,Y j ] T of the j-th transmitter, where J≧1 and K≧1.
9. A location estimation module for estimating the location of a mobile terminal having a plurality N of antennas, the module comprising:
a detector for detecting the time of arrival of a signal transmitted from M antennas of at least one transmitter at each of the N antennas of the receiver to provide M×N range measurements corresponding to the M×N transmission paths of said signal between the M antenna(e) of the transmitter and the N antennas of the mobile terminal; and
a processor for estimating, using a least square method, the location of the mobile terminal based on the M×N range measurements and the location of the at least one transmitter,
wherein the processor is operable to estimate the location of the mobile terminal by minimizing through J×K terms, the expression:
e
LS
=
∑
j
=
1
J
∑
k
=
1
K
d
~
jk
-
d
jk
(
x
^
,
y
^
)
2
where
:
d
~
jk
=
1
MN
∑
m
=
1
M
∑
n
=
1
N
d
jk
mn
d jk mn is the range measurement obtained for each signal transmission path where
j represents the transmitter number (1 to J) of J transmitters,
k represents the transmitted signal (1 to K) of K transmitted signals of the j-th transmitter,
m represents the transmitting antenna number (1 to m) of the j-th transmitter provided with M antennas, and
n represents the receiving antenna number (1 to N) of the mobile terminal provided with N antennas, and
d kj ({circumflex over (x)},ŷ) is the calculated range derived from ∥x−X∥, where x are the estimated co-ordinates [x,y] T of mobile terminal and X are the known co-ordinates [X j ,Y j ] T of base station j, where J≧1 and K≧1.
10. A location estimation module for estimating the location of a mobile terminal having a plurality N of antennas, the module comprising:
a detector for detecting the time of arrival of a signal transmitted from M antennas of at least one transmitter at each of the N antennas of the receiver to provide M×N range measurements corresponding to the M×N transmission paths of said signal between the M antenna(e) of the transmitter and the N antennas of the mobile terminal; and
a processor for estimating, using a least square method, the location of the mobile terminal based on the M×N range measurements and the location of the at least one transmitter,
wherein the processor is operable to estimate the location (x,y) of the mobile terminal by minimizing through J×K terms, the expression:
e
LS
=
∑
j
=
1
J
∑
k
=
1
K
d
~
jk
-
d
jk
(
x
^
,
y
^
)
2
where
:
d
~
jk
=
min
jk
(
d
jk
11
,
…
,
d
jk
mn
,
…
,
d
JK
MN
)
d jk mn is the range measurement obtained for each signal transmission path where
j represents the transmitter number (1 to J) of J transmitters,
k represents the transmitted signal (1 to K) of K transmitted signals of the j-th transmitter,
m represents the transmitting antenna number (1 to M) of the j-th transmitter provided with M antennas, and
n represents the receiving antenna number (1 to N) of the mobile terminal provided with N antennas, and
d kj ({circumflex over (x)},ŷ) is the calculated range derived from ∥x−X∥, where x are the estimated co-ordinates [x,y] T of mobile terminal and X are the known co-ordinates [X j ,Y j ] T of base station j, where J≧1 and K≧1.