Method of processing WCDMA signal timing offset for signal analyzing equipment
Provided is a method of processing a Wideband Code Division Multiple Access (WCDMA) signal timing offset for a signal analyzer. The method includes estimating an integer multiple timing offset of WCDMA baseband sample data corresponding to an amount of at least one frame; generating a frequency domain signal which is time delayed corresponding to a fractional timing offset estimation resolution after generating the frequency domain signal by performing a Fast Fourier Transform (FFT) calculation on an already-known reference signal; converting each time-delayed frequency domain signal into a time domain signal by performing an Inverse Fast Fourier Transform (IFFT) calculation on each time-delayed frequency domain signal and calculating a correlation between an input signal from a position of the integer multiple timing offset and the time domain signal; and estimating a delay time leading to a maximum correlation as a fractional timing offset.
1. A method of processing a Wideband Code Division Multiple Access (WCDMA) signal timing offset for a signal analyzer, the method comprising:
estimating an integer multiple timing offset of WCDMA baseband sample data corresponding to an amount of at least one frame;
generating a frequency domain signal by performing a Fast Fourier Transform (FFT) calculation on an already-known reference signal which is Root Raised Cosine (RRC)-filtered at a sampling rate;
generating at least one time-delayed frequency domain signal corresponding to at least one reference signal which is time delayed by a fractional timing offset estimation resolution;
converting the at least one time-delayed frequency domain signal into at least one time domain signal by performing an Inverse Fast Fourier Transform (IFFT) calculation on the at least one time-delayed frequency domain signal and calculating at least one correlation between at least one input signal from a position of the integer multiple timing offset and the at least one time domain signal; and
estimating a delay time leading to a maximum correlation of the at least one correlation as a fractional timing offset,
wherein the at least one delayed time domain signal is obtained by a following equation,
r ( t−τ 1 ^*i )=IFFT[ R (ω) e j*ω*τ 1 ^*i) ]
wherein τ 1 ^=T c /N 1 , I=0, . . . , N 1 , r′(t−τ 1 ^*i), and N 1 is a fractional timing offset estimation resolution.
2. The method of claim 1 , wherein the frequency domain signal R(ω) is obtained by performing the FFT calculation on a PSCH r(t) through a following equation,
R (ω)=FFT[ r ( t ), N ft ]
wherein N ft is a number of FFT samples.
3. The method of claim 2 , wherein the PSCH r(t) is a signal RRC-filtered at the sampling rate which is twice a WCDMA chip rate.
4. The method of claim 1 , wherein the frequency domain signal R(ω) is obtained by performing the FFT calculation on a CPICH r(t) through a following equation,
R (ω)=FFT[ r ( t ), N ft ],
wherein N ft is a number of FFT samples.
5. The method of claim 4 , wherein the CPICH r(t) is a signal RRC-filtered at the sampling rate which is twice a WCDMA chip rate.
6. The method of claim 1 , wherein the at least one correlation y(t) is obtained by a following equation,
y ( t )=Σ[ x ( t )* r ′( t−τ 1 ^*i )].
7. The method of claim 6 , further comprising compensating for the fractional timing offset by applying the estimated fractional timing offset to a fractional RRC filter as a compensation coefficient.
8. The method of claim 7 , wherein the RRC filter is operated according to a following equation,
RC
0
(
t
)
=
sin
(
π
t
T
C
(
1
-
α
)
)
+
4
α
t
T
C
cos
(
π
t
T
C
(
1
+
α
)
)
π
t
T
C
(
1
-
(
4
α
t
T
C
)
2
)
wherein t =t−τ 1 *i maxc .