Estimating doppler frequency in ISDB-T systems
View Patent ↗A technique for estimating maximum Doppler frequency of a wireless signal in a wireless communication system, wherein the method comprises receiving a wireless signal; determining an impulse response of the received wireless signal; determining an auto-correlation function (ACF) value of the impulse response of the received wireless signal; determining a power spectrum density of said received wireless signal based on the ACF value; and selecting an algorithm for performing demodulation of the received wireless signal by utilizing the determined power spectrum density.
1. A method for using a wireless signal in a wireless communication system, said method comprising:
receiving a wireless signal in a hardware-enabled receiver;
determining an impulse response of the received wireless signal using said receiver;
determining an auto-correlation function (ACF) value of said impulse response of said received wireless signal using said receiver, wherein said ACF value is determined by utilizing:
A
C
F
(
l
)
=
∑
n
h
(
n
)
h
*
(
l
-
n
)
h
(
n
)
,
wherein l is a symbol interval, ACF(l) is said autocorrelation function of said impulse response with a lag of l, h(n) is said impulse response of said received wireless signal at time interval n, and h*(l−n) is a complex conjugate of said impulse response h(n);
determining a power spectrum density of said received wireless signal based on said ACF value using said receiver, wherein said power spectrum density function is determined by utilizing:
PSD
(
k
)
=
FFT
(
A
C
F
(
l
)
)
=
∑
l
=
-
64
64
A
C
F
(
l
)
ⅇ
-
j2π
lk
,
wherein k is a frequency band of said received wireless signal, and wherein said FFT is a Fast Fourier Transform; and
selecting an algorithm for performing demodulation of said received wireless signal by utilizing the determined power spectrum density.
2. The method of claim 1 , wherein said utilizing the determined power spectrum density further comprises determining a maximum Doppler frequency from a power spectrum for improving reception of said wireless signal in said wireless communication system.
3. The method of claim 1 , wherein said wireless communication system comprises an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system.
4. The method of claim 2 , wherein the improved reception of said wireless signal in said wireless communication system occurs when said maximum Doppler frequency is greater than 100 Hz.
5. The method of claim 1 , wherein said hardware-enabled receiver comprises a hardware-enabled mobile receiver.
6. A method for estimating maximum Doppler frequency of a wireless signal in a wireless communication system, the method comprising:
receiving the wireless signal;
determining autocorrelation function (ACF) values for the received wireless signal, wherein said ACF values are determined for two consecutive time intervals of said received wireless signal;
estimating a ratio of the determined ACF values;
determining a value of the maximum Doppler frequency for the received signal from a predetermined lookup table by utilizing the estimated ratio of the determined ACF values; and
selecting an algorithm for performing demodulation of said received wireless signal by utilizing the determined maximum Doppler frequency.
7. The method of claim 6 , wherein said predetermined lookup table comprises a plurality of values for a ratio between autocorrelation function (ACF) values for consecutive time intervals, and wherein said ratio is estimated for a plurality of maximum Doppler frequency values by utilizing:
Bessel
Ratio
(
f
d
,
m
ax
)
=
A
C
F
(
2
)
A
C
F
(
1
)
=
J
o
(
2
π
f
d
,
m
ax
v
λ
×
2
)
J
o
(
2
π
f
d
,
m
ax
v
λ
)
,
wherein ACF(1) and ACF(2) are two adjacent ACF values, J o is a zeroth order Bessel function of a first kind, f d,max is said maximum Doppler frequency, ν is a mobility speed of a receiver of the received wireless signal, and λ is a carrier wavelength of the received wireless signal.
8. The method of claim 6 , wherein said wireless system comprises an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system.
9. The method of claim 7 , wherein using said maximum Doppler frequency, f d,max , improves reception of said wireless signal in said wireless communication system.
10. The method of claim 9 , wherein the improved reception of said wireless signal in said wireless communication system occurs when said maximum Doppler frequency is less than or equal to 100 Hz.
11. The method of claim 6 , further comprising receiving the wireless signal in a mobile receiver.
12. A non-transitory program storage device, readable by a computer, tangibly embodying a program of instructions executable by said computer to perform a method for using a wireless signal in a wireless communication system, said method comprising:
receiving the wireless signal;
determining an impulse response of the received wireless signal;
determining an auto-correlation function (ACF) value of said impulse response of said received wireless signal, wherein said ACF value is determined by utilizing:
A
C
F
(
l
)
=
∑
n
h
(
n
)
h
*
(
l
-
n
)
h
(
n
)
,
wherein l is a symbol interval, ACF(l) is said autocorrelation function of said impulse response with a lag of l, h(n) is said impulse response of said received wireless signal at time interval n, and h*(l−n) is a complex conjugate of said impulse response h(n);
determining a power spectrum density of said received wireless signal based on said ACF value, wherein said power spectrum density function is determined by utilizing:
PSD
(
k
)
=
FFT
(
A
C
F
(
l
)
)
=
∑
l
=
-
64
64
A
C
F
(
l
)
ⅇ
-
j2π
lk
,
wherein k is a frequency band of said received wireless signal, and wherein said FFT is a Fast Fourier Transform; and
selecting an algorithm for performing demodulation of said received wireless signal by utilizing the determined power spectrum density.
13. The program storage device of claim 12 , wherein said utilizing the determined power spectrum density further comprises determining a maximum Doppler frequency from a power spectrum for improving reception of said wireless signal in said wireless communication system.
14. The program storage device of claim 12 , wherein said wireless communication system comprises an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system.
15. The program storage device of claim 13 , wherein the improved reception of said wireless signal in said wireless communication system occurs when said maximum Doppler frequency is greater than 100 Hz.
16. A non-transitory program storage device, readable by a computer, tangibly embodying a program of instructions executable by said computer to perform a method for estimating maximum Doppler frequency of a wireless signal in a wireless communication system, the method comprising:
receiving the wireless signal;
determining autocorrelation function (ACF) values for the received wireless signal, wherein said ACF values are determined for two consecutive time intervals of said received wireless signal;
estimating a ratio of the determined ACF values;
determining a value of the maximum Doppler frequency for the received signal from a predetermined lookup table by utilizing the estimated ratio of the determined ACF values; and
selecting an algorithm for performing demodulation of said received wireless signal by utilizing the determined maximum Doppler frequency.
17. The program storage device of claim 16 , wherein said predetermined lookup table comprises a plurality of values for a ratio between autocorrelation function (ACF) values for consecutive time intervals, and wherein said ratio is estimated for a plurality of maximum Doppler frequency values by utilizing:
Bessel
Ratio
(
f
d
,
m
ax
)
=
A
C
F
(
2
)
A
C
F
(
1
)
=
J
o
(
2
π
f
d
,
m
ax
v
λ
×
2
)
J
o
(
2
π
f
d
,
m
ax
v
λ
)
,
wherein ACF(1) and ACF(2) are two adjacent ACF values, J o is a zeroth order Bessel function of a first kind, f d,max is said maximum Doppler frequency, ν is a mobility speed of a receiver receiving the wireless signal, and λ is a carrier wavelength of the received wireless signal.
18. The program storage device of claim 16 , wherein said wireless system comprises an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system.
19. The program storage device of claim 17 , wherein using said maximum Doppler frequency, f d,max , improves reception of said wireless signal in said wireless communication system.
20. The program storage device of claim 19 , wherein the improved reception of said wireless signal in said wireless communication system occurs when said maximum Doppler frequency is less than or equal to 100 Hz.