Method for suppressing the inter-carrier interference in the orthogonal frequency division multiplexing mobile communication system
The present invention relates to a method for suppressing inter-carrier interference in an orthogonal frequency division multiplexing mobile communication system, comprising: performing down conversion of the signal received in the receiver; removing the cyclic prefix of the signal so as to obtain the original signal; performing cyclic extension of the original signal over again; adding a window to the signal after cyclic extension, wherein the window function satisfies Nyquist criterion. The method according to the invention does not need time delay information of channels, and thereby is simple to realize. The selected roll-off coefficient can be up to 1 so as to suppress ICI to the utmost extent. Additionally, the invention also suggests that the generic window functions without the ICI can be used in OFDM system, which makes the system capability of suppressing ICI stronger by means of finding the best polynomial coefficients on the condition that the roll-off coefficient is 1.
1. A method for suppressing inter-carrier interference in an orthogonal frequency division multiplexing (OFDM) mobile communication system, comprising:
performing down-conversion of a signal received at a receiving end;
removing a cyclic prefix of the signal to obtain an original signal containing original OFDM symbols at the receiving end;
reattaching the cyclic prefix to the original signal at the receiving end after the receiving end removing the cyclic prefix of the signal; and
performing an operation of window adding by a window function at the receiving end, wherein frequency spectrum of the window function in said operation of window adding is:
W
r
(
f
)
=
sin
c
(
fT
u
)
[
-
2
(
a
1
+
2
a
2
)
sin
c
(
α
fT
u
)
+
2
a
2
sin
c
2
(
α
2
fT
u
)
+
2
(
a
0
+
a
1
+
a
2
)
cos
(
απ
fT
u
)
+
1
-
2
a
0
]
wherein sinc(f)=sin(πf)/πf, f represents frequency, T u represents width of the original signal, α represents roll-off coefficient, a 0 represents zero order coefficient of normalized fundamental function, a 1 represents first order coefficient of normalized fundamental function, and a 2 represents second order coefficient of normalized fundamental function.
2. The method of claim 1 , wherein reattaching the cyclic prefix comprises copying part or all of the original OFDM symbols to be put before the original OFDM symbols.
3. The method of claim 1 , wherein a 0 =0.5, a 2 =−0.5−a 1 , the frequency spectrum of said window function is
W
r
(
f
)
=
sin
c
(
fT
u
)
[
2
(
1
+
a
1
)
sin
c
(
α
fT
u
)
-
(
1
+
2
a
1
)
sin
c
2
(
α
2
fT
u
)
]
.
4. The method of claim 1 , wherein said roll-off coefficient is 1.
5. The method of claim 3 , wherein said roll-off coefficient is 1.