Method and apparatus for searching carrier frequencies
A method and apparatus for searching carrier frequencies (CFs) including determining all CFs to be measured within a frequency band according to a predetermined frequency interval; selecting part of the CFs as Sampling Measurement CFs (SMCFs) according to a predetermined band search step, and for each of the SMCFs, calculating initial peak to average ratio (PAR) of the SMCFs; weighting the initial PAR of each of the SMCFs by using initial PARs of SMCFs left and right neighboring each of the SMCFs, to obtain a determined PAR of each of the SMCFs; ordering the determined PARs of all the SMCFs, and selecting, in a descending order of the determined PARs, a predetermined number of SMCFs and frequencies to be measured left and right neighboring the selected SMCFs as a search result.
1. A method for searching carrier frequencies, comprising:
determining all the carrier frequencies to be measured within a frequency band according to a predetermined frequency interval;
selecting a part of the carrier frequencies to be measured as sampling measurement carrier frequencies according to a predetermined band search step, and for each of the sampling measurement carrier frequencies, calculating an initial peak to average ratio of the sampling measurement carrier frequencies;
weighting the initial peak to average ratio of each of the sampling measurement carrier frequencies by using initial peak to average ratios of sampling measurement carrier frequencies left and right neighboring the each of the sampling measurement carrier frequencies, so as to obtain a determined peak to average ratio of the each of the sampling measurement carrier frequencies; and
ordering the determined peak to average ratios of all the sampling measurement carrier frequencies, and selecting, in a descending order of the determined peak to average ratios, a predetermined number of sampling measurement carrier frequencies and frequencies to be measured left and right neighboring the selected sampling measurement carrier frequencies as a search result.
2. The method according to claim 1 , wherein for each of the sampling measurement carrier frequencies, the step of calculating an initial peak to average ratio of the sampling measurement carrier frequency comprises:
on the sampling measurement carrier frequency, performing segment association on a received signal by using a local Primary Synchronization Signal (PSS), so as to obtain a PSS sequence and peak value position of the sampling measurement carrier frequency; and
calculating the initial peak to average ratio of the sampling measurement carrier frequency according to the PSS sequence and peak value position of the sampling measurement carrier frequency.
3. The method according to claim 2 , wherein the segment association on the received signal is performed according to the formula as follows:
C
(
n
ZC
,
k
)
=
(
1
(
N
FFT
-
2
)
/
3
∑
l
=
0
(
N
FFT
-
2
)
/
3
-
1
r
(
k
+
l
)
p
*
(
n
ZC
,
l
)
)
*
(
1
(
N
FFT
-
2
)
/
3
∑
l
=
(
N
FFT
-
2
)
/
3
2
(
N
FFT
-
2
)
/
3
-
1
r
(
k
+
l
)
p
*
(
n
ZC
,
l
)
)
and
+
(
1
(
N
FFT
-
2
)
/
3
∑
l
=
(
N
FFT
-
2
)
/
3
2
(
N
FFT
-
2
)
/
3
-
1
r
(
k
+
l
)
p
*
(
n
ZC
,
l
)
)
*
(
1
(
N
FFT
-
2
)
/
3
∑
l
=
2
(
N
FFT
-
2
)
/
3
(
N
FFT
-
2
)
-
1
r
(
k
+
l
)
p
*
(
n
ZC
,
l
)
)
the PSS sequence and peak value position of the sampling measurement carrier frequency are expressed as:
(
n
Z
C
_
max
,
k
max
)
=
arg
max
(
n
ZC
,
k
)
C
(
n
ZC
,
k
)
2
;
where, r(k) is a sampling point of a received signal in time domain, p(n ZC ,l) is a local PSS, n ZC is a serial number of the PSS, and N FFT is the point number of a FFT.
4. The method according to claim 2 , wherein the initial peak to average ratio of the sampling measurement carrier frequency is calculated according to the formula as follows:
C
ratio
f
c
=
1
2
W
mask
+
1
∑
k
=
k
max
-
W
mask
k
max
+
W
mask
C
(
n
ZC
_
max
,
k
)
2
1
T
SCH
T
slot
-
(
2
W
mask
+
1
)
(
∑
k
=
0
k
max
-
W
mask
-
1
C
(
n
ZC
_
max
,
k
)
2
+
∑
k
=
k
max
+
W
mask
+
1
T
SCH
T
slot
-
1
C
(
n
ZC
_
max
,
k
)
2
)
;
where, W mask is the point number of a peak value window, and T SCH T slot is the number of sampling points of 5 ms of search time.
5. The method according to claim 1 , wherein for each of the sampling measurement carrier frequencies, the determined peak to average ratio of the sampling measurement carrier frequency is obtained by weighting the initial peak to average ratio of the sampling measurement carrier frequency by using initial peak to average ratios of the sampling measurement carrier frequencies left and right neighboring the sampling measurement carrier frequency, according to the formula as follows:
C
ratio
f
c
′
=
∑
i
=
-
M
M
α
i
C
ratio
f
c
+
i
;
where, the weighting coefficient is
a
i
=
1
or
α
i
=
M
+
1
-
i
M
+
1
,
M is the number of the left and right neighboring carrier frequencies.
6. The method according to claim 1 , wherein the predetermined frequency interval is 100 kHz, and the predetermined band search step is n>=1.
7. The method according to claim 6 , wherein when the sampling measurement carrier frequency is f c , the carrier frequencies to be measured left and right neighboring the sampling measurement carrier frequency are f c +100(n−1), . . . , f c +100 [kHz] and f c −100 (n−1), . . . , f c −100 [kHz], respectively; where, n>=1.
8. The method according to claim 7 , wherein when the sampling measurement carrier frequency is f c ,
if n=2, the carrier frequencies to be measured left and right neighboring the sampling measurement carrier frequency are f c +100(2−)=f c +100 and f c −100(2−1)=f c −100, respectively;
if n=3, the carrier frequencies to be measured left and right neighboring the sampling measurement carrier frequency are f c +100(3−1)=f c +200, f c +100(2−1)=f c +100 and f c −100(3−1)=f c −200, f c −100(2−1)=f c −100, respectively; and
if n=4, the carrier frequencies to be measured left and right neighboring the sampling measurement carrier frequency are f c +100(4−1)=f c +300, f c +100(3−1)=f c +200, f c +100(2−1)=f c +100 and f c −100(4−1)=f c −300, f c −100(3−1)=f c −200, f c −100(2−1)=f c −100, respectively.
9. An apparatus for searching carrier frequencies, comprising:
a processor configured to perform the functions of:
determining all the carrier frequencies to be measured within a frequency band according to a predetermined frequency interval;
selecting a part of the carrier frequencies to be measured as sampling measurement carrier frequencies according to a predetermined band search step, and for each of the sampling measurement carrier frequencies, calculating an initial peak to average ratio of the sampling measurement carrier frequency;
weighting the initial peak to average ratio of each of the sampling measurement carrier frequencies by using initial peak to average ratios of sampling measurement carrier frequencies left and right neighboring the each of the sampling measurement carrier frequencies, so as to obtain a determined peak to average ratio of the each of the sampling measurement carrier frequencies; and
ordering the determined peak to average ratios of all the sampling measurement carrier frequencies, and selecting, in a descending order of the determined peak to average ratios, a predetermined number of sampling measurement carrier frequencies and frequencies to be measured left and right neighboring the selected sampling measurement carrier frequencies as a search result.