Method and apparatus for transmitting a signal in a communication system
A method and apparatus for processing time windowing to transmit a signal in a Broadband Wireless Access (BWA) communication system based on Orthogonal Frequency Division Multiple Access (OFDMA). A signal of a first interval included in a previous symbol prior to a current symbol is stored as a signal of a previous symbol interval. The current symbol includes a guard interval and an effective symbol interval subsequent to the guard interval. The current symbol is windowed by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol. A windowed signal is transmitted.
1. A method for transmitting a signal in a communication system including a symbol buffer and a windowing processor, comprising the steps of:
storing, by the symbol buffer, a signal of a first interval included in a previous symbol prior to a current symbol as a signal of a previous symbol interval, the current symbol including a guard interval and an effective symbol interval subsequent the guard interval; and
windowing, by the windowing processor, the current symbol based on a window size by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol and transmitting a windowed signal,
wherein the first interval is an interval corresponding to the window size from a start point of the effective symbol interval included in the previous symbol,
wherein the second interval is an interval corresponding to the window size from a start point of the guard interval included in the current symbol,
wherein the windowing step comprises:
multiplying the signal of the second interval by a preset first windowing coefficient and multiplying the signal of the first interval by a preset second windowing coefficient; and
adding and overlapping the signal of the second interval multiplied by the first windowing coefficient and the signal of the first interval multiplied by the second windowing coefficient, and
wherein the first and second windowing coefficient are computed by:
W
1
(
n
)
=
0.5
×
(
1
+
cos
(
π
×
(
1
+
n
win_size
)
)
)
,
for
n
=
0
,
…
,
win_size
-
1
W
2
(
n
)
=
1
-
W
1
(
n
)
,
for
n
=
0
,
…
,
win_size
-
1
where W 1 (n) denotes the first windowing coefficient, W 2 (n) denotes the second windowing coefficient, and win size denotes sizes of the first and second intervals.
2. The method of claim 1 , wherein the sizes of the first and second intervals are each equal to a window size.
3. The method of claim 2 , wherein the window size is smaller than a size of the guard interval included in the current symbol.
4. An apparatus for transmitting a signal in a communication system, comprising:
a symbol buffer for storing a signal of a first interval included in a previous symbol prior to a current symbol as a signal of a previous symbol interval, the current symbol including a guard interval and an effective symbol interval subsequent the guard interval; and
a windowing processor for windowing the current symbol based on a window size by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol and transmitting a windowed signal,
wherein the first interval is an interval corresponding to the window size from a start point of the effective symbol interval included in the previous symbol,
wherein the second interval is an interval corresponding to the window size from a start point of the guard interval include in the current symbol,
wherein the windowing processor multiplies the signal of the second interval by a preset first windowing coefficient, multiplies the signal of the first interval by a preset second windowing coefficient, and adds and overlaps the signal of the second interval multiplied by the first windowing coefficient and the signal of the first interval multiplied by the second windowing coefficient, and
wherein the first and second windowing coefficient are computed by:
W
1
(
n
)
=
0.5
×
(
1
+
cos
(
π
×
(
1
+
n
win_size
)
)
)
,
for
n
=
0
,
…
,
win_size
-
1
W
2
(
n
)
=
1
-
W
1
(
n
)
,
for
n
=
0
,
…
,
win_size
-
1
where W 1 (n) denotes the first windowing coefficient, W 2 (n) denotes the second windowing coefficient, and win size denotes size of the first and second intervals.
5. The apparatus of claim 4 , wherein the sizes of the first and second intervals are each equal to a window size.
6. The apparatus of claim 5 , wherein the window size is smaller than a size of the guard interval included in the current symbol.
7. The apparatus of claim 4 , further comprising:
a windowing coefficient table memory for storing at least one of the first and second windowing coefficients and transferring the at least one stored windowing coefficient to the windowing processor.