Method and apparatus for mobile radio velocity estimation
View Patent ↗A mobile radio velocity estimation system ( 100 ) includes an autocorrelation block ( 106 ) that determines the autocorrelation of a received signal ( 104 ) using one lag ( 102 ). A power determination block ( 108 ) determines the power of the received signal ( 104 ) and a divider block ( 114 ) divides the autocorrelation ( 110 ) by the power ( 112 ). Using a Bessel function lookup table ( 116 ) and a multiplication by λ/τ block ( 118 ), an estimate ( 120 ) for the mobile radio's velocity can be calculated. A method for estimating the velocity of a mobile radio ( 500 ) is also discussed.
1. A radio, comprising:
a receiver for receiving a radio signal; and
a velocity estimation block coupled to the receiver for estimating the velocity of the radio, the velocity estimation block including:
an autocorrelation block coupled to the receiver for determining the
autocorrelation of the received signal using a predetermined lag;
a power block coupled to the receiver for determining the power of the received signal; and
a Bessel lookup table coupled to the autocorrelation and power blocks for estimating the velocity of the radio;
wherein the velocity estimation block estimates the velocity of the radio using the equation
v
=
λ
InverseJ
0
(
E
[
r
(
t
)
r
(
t
-
τ
)
]
E
[
r
(
t
)
2
]
)
2
πτ
,
where,
E[r(t)r(t−τ)] Autocorrelation of the received signal,
τ Lag associated with the correlation,
E[r(t) 2 ] Signal power,
J 0 Bessel function of order 0 ,
v Velocity of the radio communication device,
λ Wavelength of the signal; and
Inverse J 0 0 values found in the inverse Bessel function table.
2. A radio as defined in claim 1 , wherein the Bessel lookup table comprises an inverse Bessel lookup table.
3. A radio as defined in claim 2 , wherein the autocorrelation determined by the autocorrelation block is divided by the power determined by the power block in order to determine the inverse Bessel function of 2πf d τ, where f d is the Doppler frequency caused by the movement of the radio and τ is the predetermined lag.
4. A radio as defined in claim 3 , wherein the predetermined lag is stored in the radio.
5. A radio as defined in claim 4 , wherein the inverse Bessel lockup table is stored in the radio.
6. A radio us defined in claim 5 , comprises a cellular telephone.
7. A radio as defined in claim 1 , wherein the velocity estimation block comprises a Digital Signal Processor performing velocity estimation calculations.
8. A radio as defined in claim 1 , wherein the lag (tau) is chosen from the interval 0.0<=tau<=^/(pi*vmax), where vmax is the maximum velocity of the mobile radio and ^ is the wavelength of the received signal.
9. A method for estimating the velocity of a radio communication device, comprising the steps of:
receiving a signal at the radio communication device;
computing the power of the received signal;
computing the autocorrelation of the received signal using a single lag associated with the correlation; and
using an inverse Bessel function table and the computed power and autocorrelation to provide an estimate of the velocity of the radio communication device;
wherein the single lag and the inverse Bessel function table are stored in the radio communication device; and
wherein the method is performed using a controller that uses the equation:
v
=
λ
InverseJ
0
(
E
[
r
(
t
)
r
(
t
-
τ
)
]
E
[
r
(
t
)
2
]
)
2
πτ
,
where,
E[r(t)r(t−τ)] Autocorrelation of the received signal,
τ Lag associated with the correlation,
E[r(t) 2 ] Signal power,
J 0 Bessel function of order 0 ,
v Velocity of the radio communication device,
λ Wavelength of the signal; and
Inverse J 0 0 values found in the inverse Bessel function table.