Method and device for determining a decoding mode of in-band signaling
View Patent ↗In the field of communications, a method and a device for determining a decoding mode of in-band signaling are provided, which improve accuracy of in-band signaling decoding. The method includes: calculating a probability of each decoding mode of in-band signaling of a received signal at a predetermined moment by using a posterior probability algorithm; and from the calculated probabilities of the decoding modes, selecting a decoding mode having a maximum probability value as a decoding mode of the in-band signaling of the received signal at the predetermined moment. The method and the device are mainly used in a process for determining a decoding mode of in-band signaling in a speech frame transmission process.
1. A method for determining a decoding mode of in-band signaling, the method comprising:
calculating, by a mobile station, a probability of each decoding mode of in-band signaling of a signal received at the mobile station at a predetermined moment by using a posterior probability algorithm by:
obtaining, according to a posterior probability principle, a probability formula for calculating the probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment:
p
(
st
k
=
m
r
k
)
=
p
(
r
k
st
k
=
m
)
p
(
st
k
=
m
)
p
(
r
k
)
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at a moment k, and r k is a received signal vector,
taking logarithms of two sides of the probability formula, and simplifying the probability formula according to a relationship between the received signal and a demodulated soft value to obtain a simplified probability formula:
ln
p
(
st
k
=
m
r
k
)
⇔
∑
i
=
0
3
λ
ki
s
ki
2
+
ln
p
(
st
k
=
m
)
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at a moment k, λ is a demodulated soft value of the received signal, and s is encoded data of a sent signal, and
calculating a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment, and substituting the logarithmic priori probability into the simplified probability formula to obtain a probability of a corresponding decoding mode of the received signal at the predetermined moment; and
selecting, at the mobile station, from calculated probabilities of decoding modes, a decoding mode having a maximum probability value as a decoding mode of the in-band signaling of the received signal at the predetermined moment.
2. The method for determining a decoding mode of in-band signaling according to claim 1 , wherein calculating the logarithmic priori probability of each decoding mode of the in-band signaling of the received signal at the predetermined moment comprises:
obtaining a priori probability calculation formula of a predetermined decoding mode of the in-band signaling of the received signal at the predetermined moment according to a priori probability algorithm:
p ( st k =m )= p 0m p ( st k-1 =0| r k-1 )+ p 1m p ( st k-1 =1| r k-1 )+ p 2m p ( st k-1 =2| r k-1 )+ p 3m p ( st k-1 =3| r k-1 )
wherein r k is a received signal vector, st k-1 m=0, 1, 2, 3, st k is one of four in-band signaling decoding modes at a moment k, st k-1 is one of four in-band signaling decoding modes at a moment k-1, P 0m , P 1m , P 3m are probabilities of conversion from four decoding modes 0, 1, 2, and 3 at the moment k-1 to mode m at the moment k, respectively, and p(st k =m) is a priori probability when the decoding mode at the moment k is mode m;
taking logarithms of two sides of the priori probability calculation formula to obtain a logarithmic priori probability formula of the decoding mode of the in-band signaling of the received signal at the predetermined moment:
ln p ( st k =m )=max(ln p 0m +ln p ( st k-1 =0| r k-1 ),ln p 1m +ln p ( st k-1 =1| r k-1 ),
ln p 2m +ln p ( st k-1 =2| r k-1 ),ln p 3m +ln p ( st k-1 =3| r k-1 ))
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, and r k is the received signal vector;
calculating a posterior probability of each decoding mode of in-band signaling of a received signal at a moment previous to the predetermined moment, and determining a probability of conversion from a decoding mode at the moment previous to the predeteimined moment to the predetermined decoding mode at the predetermined moment; and
substituting the posterior probability of each decoding mode and the probability of conversion into the logarithmic priori probability formula to obtain a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment.
3. The method for determining a decoding mode of in-band signaling according to claim 2 , wherein after taking the logarithms of the two sides of the priori probability calculation formula acquired by an acquiring sub-module to obtain the logarithmic priori probability formula of the decoding mode of the in-band signaling of the received signal at the predetermined moment, the method further comprises:
further simplifying the logarithmic priori probability formula according to data sending characteristics of the in-band signaling to obtain a simplified logarithmic priori probability calculation formula:
ln p ( st k =0)=max(ln p 00 +ln p ( st k-1 =0 |r k-1 )ln p 10 +ln p ( st k-1 =1 |r k-1 ))
ln p ( st k =1)=max(ln p 01 +ln p ( st k-1 =0 |r k-1 )ln p 11 +ln p ( st k-1 =1 |r k-1 )ln p 21 +ln p ( st k-1 =2 |r k-1 ))
ln p ( st k =2)=max(ln p 12 +ln p ( st k-1 =1 |r k-1 )ln p 22 +ln p ( st k-1 =2 |r k-1 )ln p 32 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =3)=max(ln p 23 +ln p ( st k-1 =2 |r k-1 )ln p 33 +ln p ( st k-1 =3 |r k-1 ))
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, and r k is the received signal vector; and
substituting the posterior probability of each decoding mode and the probability of conversion that are obtained through calculation into the simplified logarithmic priori probability formula to obtain a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment.
4. The method for determining a decoding mode of in-band signaling according to claim 2 , wherein after taking the logarithms of the two sides of the priori probability calculation formula acquired by an acquiring sub-module to obtain the logarithmic priori probability formula of the decoding mode of the in-band signaling of the received signal at the predetermined moment, the method further comprises:
obtaining the following logarithmic priori probability calculation formula according to data sending characteristics of the in-band signaling and according to the logarithmic priori probability formula:
ln p ( st k =0)=max(ln p 00 +ln p ( st k-1 =0 |r k-1 )ln p 10 +ln p ( st k-1 =1 |r k-1 )ln p 20 +ln p ( st k-1 =2 |r k-1 )ln p 30 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =1)=max(ln p 01 +ln p ( st k-1 =0 |r k-1 )ln p 11 +ln p ( st k-1 =1 |r k-1 )ln p 21 +ln p ( st k-1 =2 |r k-1 )ln p 31 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =2)=max(ln p 02 +ln p ( st k-1 =0 |r k-1 )ln p 12 +ln p ( st k-1 =1 |r k-1 )ln p 22 +ln p ( st k-1 =2 |r k-1 )ln p 32 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =3)=max(ln p 03 +ln p ( st k-1 =0 |r k-1 )ln p 13 +ln p ( st k-1 =1 |r k-1 )ln p 32 +ln p ( st k-1 =2 |r k-1 )ln p 33 +ln p ( st k-1 =3 |r k-1 ))
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, and r k is the received signal vector; and
substituting the posterior probability of each decoding mode and the probability of conversion that are obtained through calculation into the simplified logarithmic priori probability formula to obtain a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment.
5. The method for determining a decoding mode of in-band signaling according to claim 2 , wherein calculating the posterior probability of each decoding mode of the in-band signaling of the received signal at the moment previous to the predetermined moment comprises:
specifying a decoding mode of the in-band signaling of the received signal at the moment previous to the predetermined moment;
setting a posterior probability of the specified decoding mode to 1, and setting posterior probabilities of decoding modes other than the specified decoding mode to 0; or calculating, according to a posterior probability principle, the posterior probability of each decoding mode of the in-band signaling of the received signal at the moment previous to the predetermined moment.
6. A device for determining a decoding mode of in-band signaling, the device comprising:
a calculating unit, configured to calculate a probability of each decoding mode of in-band signaling of a received signal at a predetermined moment by using a posterior probability algorithm; and
a selecting unit, configured to select, from calculated probabilities of decoding modes, a decoding mode having a maximum probability value as a decoding mode of the in-band signaling of the received signal at the predetermined moment.
7. A device for determining a decoding mode of in-band signaling according to claim 6 , wherein the calculating unit comprises:
a formula acquiring module, configured to obtain, according to a posterior probability principle, a probability formula for calculating the probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment:
p
(
st
k
=
m
r
k
)
=
p
(
r
k
st
k
=
m
)
p
(
st
k
=
m
)
p
(
r
k
)
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at a moment k, and r k is a received signal vector;
a formula simplifying module, configured to take logarithms of two sides of the probability formula acquired by the formula acquiring module, and simplify the probability formula according to a relationship between the received signal and a demodulated soft value to obtain a simplified probability formula:
ln
p
(
st
k
=
m
r
k
)
⇔
∑
i
=
0
3
λ
ki
s
ki
2
+
ln
p
(
st
k
=
m
)
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, λ a demodulated soft value of the received signal, and s is encoded data of a sent signal, and
a calculating module, configured to calculate a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment, and substitute the logarithmic priori probability into the probability formula simplified by the formula simplifying module to obtain a probability of a corresponding decoding mode of the received signal at the predetermined moment.
8. A device for determining a decoding mode of in-band signaling according to claim 7 , wherein the calculating module comprises:
an acquiring sub-module, configured to obtain a priori probability calculation formula of a predetermined decoding mode of the in-band signaling of the received signal at the predetermined moment according to a priori probability algorithm:
p ( st k =m )= p 0m p ( st k-1 =0| r k-1 )+ p 1m p ( st k-1 =1| r k-1 )+ p 2m p ( st k-1 =2| r k-1 )+ p 3m p ( st k-1 =3| r k-1 )
wherein r k is a received signal vector, st k-1 =m, st k =m, m=0, 1, 2, 3, st k is one of four in-band signaling decoding modes at a moment k, st k-1 is one of four in-band signaling decoding modes at a moment k-1, P 0m , P 1m , P 2m , and P 3m are respectively probabilities of conversion from four decoding modes 0, 1, 2, and 3 at the moment k-1 to mode m at the moment k, and p(st k =m) is a priori probability when the decoding mode at the moment k is mode m;
a first calculating sub-module, configured to take logarithms of two sides of the priori probability calculation formula to obtain a logarithmic priori probability formula of the decoding mode of the in-band signaling of the received signal at the predetermined moment:
ln p ( st k =m )=max(ln p 0m +ln p ( st k-1 =0| r k-1 ),ln p 1m +ln p ( st k-1 =1| r k-1 ),
ln p 2m +ln p ( st k-1 =2| r k-1 ),ln p 3m +ln p ( st k-1 =3| r k-1 ))
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, and r k is the received signal vector;
a second calculating sub-module, configured to calculate a posterior probability of each decoding mode of in-band signaling of a received signal at a moment previous to the predetermined moment, and determine a probability of conversion from a decoding mode at the moment previous to the predetermined moment to the predetermined decoding mode at the predetermined moment; and
a third calculating sub-module, configured to substitute the posterior probability of each decoding mode and the probability of conversion that are calculated by the second calculating sub-module into the logarithmic priori probability formula to obtain a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment.
9. A device for determining a decoding mode of in-band signaling according to claim 8 , wherein the calculating module further comprises:
a formula simplifying sub-module, configured to, after the taking the logarithms of the two sides of the priori probability calculation formula obtained by the acquiring sub-module to obtain the logarithmic priori probability formula of the decoding mode of the in-band signaling of the received signal at the predetermined moment, further simplify the logarithmic priori probability formula according to data sending characteristics of the in-band signaling to obtain the simplified logarithm priori probability calculation formula:
ln p ( st k =0)=max(ln p 00 +ln p ( st k-1 =0 |r k-1 )ln p 10 +ln p ( st k-1 =1 |r k-1 ))
ln p ( st k =1)=max(ln p 01 +ln p ( st k-1 =0 |r k-1 )ln p 11 +ln p ( st k-1 =1 |r k-1 )ln p 21 +ln p ( st k-1 =2 |r k-1 ))
ln p ( st k =2)=max(ln p 12 +ln p ( st k-1 =1 |r k-1 )ln p 22 +ln p ( st k-1 =2 |r k-1 )ln p 32 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =3)=max(ln p 23 +ln p ( st k-1 =2 |r k-1 )ln p 33 +ln p ( st k-1 =3 |r k-1 ))
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, and r k is the received signal vector; and
the third calculating sub-module is further configured to substitute the posterior probability of each decoding mode and the probability of conversion that are calculated by the second calculating sub-module into the logarithmic priori probability formula simplified by the simplifying module to obtain a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predetermined moment.
10. A device for determining a decoding mode of in-band signaling according to claim 8 , wherein the calculating module further comprises:
a fourth calculating sub-module, configured to, after the taking the logarithms of the two sides of the priori probability calculation formula obtained by the acquiring sub-module to obtain the logarithmic priori probability formula of the decoding mode of the in-band signaling of the received signal at the predetermined moment, obtain the following logarithmic priori probability calculation formula according to data sending characteristics of the in-band signaling and the logarithmic priori probability formula:
ln p ( st k =0)=max(ln p 00 +ln p ( st k-1 =0 |r k-1 )ln p 10 +ln p ( st k-1 =1 |r k-1 )ln p 20 +ln p ( st k-1 =2 |r k-1 )ln p 30 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =1)=max(ln p 01 +ln p ( st k-1 =0 |r k-1 )ln p 11 +ln p ( st k-1 =1 |r k-1 )ln p 21 +ln p ( st k-1 =2 |r k-1 )ln p 31 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =2)=max(ln p 02 +ln p ( st k-1 =0 |r k-1 )ln p 12 +ln p ( st k-1 =1 |r k-1 )ln p 22 +ln p ( st k-1 =2 |r k-1 )ln p 32 +ln p ( st k-1 =3 |r k-1 ))
ln p ( st k =3)=max(ln p 03 +ln p ( st k-1 =0 |r k-1 )ln p 13 +ln p ( st k-1 =1 |r k-1 )ln p 32 +ln p ( st k-1 =2 |r k-1 )ln p 33 +ln p ( st k-1 =3 |r k-1 ))
wherein st k =m, m=0, 1, 2, 3, which is one of four in-band signaling decoding modes at the moment k, and r k is the received signal vector, and
the third calculating sub-module is further configured to substitute the posterior probability of each decoding mode and the probability of conversion that are calculated by the second calculating sub-module into the logarithmic priori probability formula simplified by the simplifying module to obtain a logarithmic priori probability of the decoding mode of the in-band signaling of the received signal at the predeteimined moment.
11. A device for determining a decoding mode of in-band signaling according to claim 8 , wherein the first calculating sub-module comprises:
specifying a decoding mode of the in-band signaling of the received signal at the moment previous to the predetermined moment;
setting a posterior probability of the specified decoding mode to 1, and setting posterior probabilities of decoding modes other than the specified decoding mode to 0; or
calculating, according to a posterior probability principle, a posterior probability of each decoding mode of the in-band signaling of the received signal at the moment previous to the predetermined moment.