INTERPOLATING METHOD FOR AN OFDM SYSTEM AND CHANNEL ESTIMATION METHOD AND APPARATUS
The present invention provides an interpolating method for an OFDM system, a channel estimation method and apparatus, in which each OFDM symbol has scattered pilots inserted, and the interpolating method comprising: the step of inserting at least one copy of the first scattered pilot in each OFDM symbol before the first scattered pilot as virtual pilots, and inserting at least one copy of the last scattered pilot in each OFDM symbol behind the last scattered pilot as virtual pilots, after obtaining the channel state information on the sub-channels which propagate the scattered pilots in the OFDM symbols by linear filtering; and the step of performing interpolation by a FIR filter with the channel state information.
1 - 12 . (canceled)
13 . An interpolating method for an OFDM system in which each OFDM symbol has scattered pilots inserted therein, comprising:
inserting at least one copy of the first scattered pilot in each OFDM symbol before the first scattered pilot as virtual pilots, and inserting at least one copy of the last scattered pilot in each OFDM symbol behind the last scattered pilot as virtual pilots, after obtaining the channel state information on the sub-channels which propagate the scattered pilots in the OFDM symbols; and
performing interpolation by a FIR filter with the channel state information.
14 . The interpolating method according to claim 13 , wherein the channel state information is obtained by performing linear filtering to the OFDM symbols.
15 . The interpolating method according to claim 13 , wherein the interpolation can be performed according to the following formula:
csi_f
_int
p
(
m
,
n
)
=
∑
i
=
1
fil_len
csi_t
_int
p
(
m
,
n
-
3
2
·
fil_len
+
3
gi
-
2
)
·
fil_co
(
i
)
16 . The interpolating method according to claim 13 , wherein the interval between the inserted scattered pilots satisfies Nyquist sampling theorem.
17 . The interpolating method according to claim 13 , wherein the number of the virtual pilots is determined to be half length of the FIR filter.
18 . A channel estimation method for an OFDM system, comprising:
estimating CSI of received scattered pilots in OFDM symbols by dividing the known transmitted scattered pilots;
obtaining the channel state information on the sub-channel which propagate the scattered pilots and storing the channel state information; and
inserting at least one copy of the first scattered pilot in each OFDM symbol before the first scattered pilot as virtual pilots and inserting at least one copy of the last scattered pilot in each OFDM symbol behind the last scattered pilot as virtual pilots, and performing channel estimation by interpolating with a FIR filter using the channel state information.
19 . The channel estimation method according to claim 18 , wherein the channel state information is obtained by performing linear filtering to the OFDM symbols.
20 . The channel estimation method according to claim 18 , wherein the interpolation can be performed according to the following formula:
csi_f
_int
p
(
m
,
n
)
=
∑
i
=
1
fil_len
csi_t
_int
p
(
m
,
n
-
3
2
·
fil_len
+
3
gi
-
2
)
·
fil_co
(
i
)
21 . The channel estimation method according to claim 18 , wherein the interval between the inserted scattered pilots satisfies Nyquist sampling theorem.
22 . The channel estimation method according to claims 18 , wherein the number of the virtual pilots is determined to be half length of the FIR filter.
23 . A channel estimation apparatus, comprising:
a pre-processor for performing channel estimation of the scattered pilots in OFDM symbols;
a time domain interpolation module, coupled to the pre-processor, for obtaining the channel state information on the sub-channels which propagate the scattered pilots; and
a frequency domain interpolation module, coupled to the time domain interpolation module, for inserting at least one copy of the first scattered pilot in each OFDM symbol before the first scattered pilot as virtual pilots, and inserting at least one copy of the last scattered pilot in each OFDM symbol behind the last scattered pilot as virtual pilots, and performing channel estimation by interpolating with a FIR filter using the channel state information.
24 . The channel estimation apparatus according to claim 23 , wherein the time domain interpolation module performs linear filtering to the OFDM symbols to obtain the channel state information.
25 . The channel estimation apparatus according to claim 23 , wherein the interpolation can be performed according to the following formula:
csi_f
_int
p
(
m
,
n
)
=
∑
i
=
1
fil_len
csi_t
_int
p
(
m
,
n
-
3
2
·
fil_len
+
3
gi
-
2
)
·
fil_co
(
i
)
26 . The channel estimation apparatus according to claim 23 , wherein the interval between the inserted scattered pilots satisfies Nyquist sampling theorem.
27 . The channel estimation apparatus according to claim 23 , wherein the number of the virtual pilots is determined to be half length of the FIR filter.