CARRIER FREQUENCY OFFSET ESTIMATION DEVICE AND CARRIER FREQUENCY OFFSET ESTIMATION METHOD
A carrier frequency offset (CFO) estimation device includes an echo cancelling unit, performing echo cancellation on an input signal to generate an echo-cancelled signal; and a CFO estimating unit, performing CFO estimation on the echo-cancelled signal to generate an estimated CFO.
1 . A carrier frequency offset (CFO) device, comprising:
an echo cancelling unit, performing echo cancellation on a received signal to generate an echo-cancelled signal; and
a CFO estimating unit, performing CFO estimation on the echo-cancelled signal to generate an estimated CFO.
2 . The CFO estimation device according to claim 1 , wherein the echo cancelling unit is a whitening filter.
3 . The CFO estimation device according to claim 2 , wherein the whitening filter comprises:
a shift register, storing a plurality of symbols of the received signal;
a first multiplication unit, respectively multiplying the plurality of symbols by a plurality of coefficients to generate a plurality of first products;
a summing unit, summing up the plurality of first products to generate a product sum; and
a subtraction unit, performing a subtraction calculation according to the product sum and a selected symbol of the received signal to generate the echo-cancelled signal.
4 . The CFO estimation device according to claim 3 , further comprising:
a coefficient providing unit, updating the plurality of coefficients according to the echo-cancelled signal and the plurality of symbols to generate a plurality of updated coefficients.
5 . The CFO estimation device according to claim 3 , wherein the coefficient providing unit comprises:
a conjugate unit, performing a conjugate operation on the plurality of symbols to generate a plurality of conjugate symbols;
a second multiplication unit, respectively multiplying the plurality of conjugate symbols by the echo-cancelled signal and a step size to generate a plurality of coefficient adjustment values; and
an adding unit, adding the plurality of coefficient adjustment values to the plurality coefficients to generate the plurality of updated coefficients.
6 . The CFO estimation device according to claim 3 , wherein the selected symbol is a symbol received earliest among the plurality of symbols so as to cancel post-echo in the received signal.
7 . The CFO estimation device according to claim 3 , wherein the selected symbol is a next symbol of the received signal so as to cancel pre-echo in the received signal.
8 . A carrier frequency offset (CFO) estimation method, comprising:
performing echo cancellation on a received signal to generate an echo-cancelled signal; and
performing CFO estimation according to the echo-cancelled signal to generate an estimated CFO.
9 . The CFO estimation method according to claim 8 , wherein the step of performing the echo cancellation on the received signal to generate the echo-cancelled signal comprises:
storing a plurality of symbols of the received signal;
multiplying the plurality of symbols by a plurality of coefficients, respectively, to generate a plurality of first products;
summing up the plurality of first products to generate a product sum; and
performing a subtraction calculation according to the product sum and a selected symbol of the received signal to generate the echo-cancelled signal.
10 . The CFO estimation method according to claim 9 , further comprising:
updating the plurality of coefficients according to the echo-cancelled signal and the plurality of symbols to generate a plurality of updated coefficients.
11 . The CFO estimation method according to claim 10 , wherein the step of updating the plurality of coefficients according to the echo-cancelled signal and the plurality of symbols to generate the plurality of updated coefficients comprises:
performing a conjugate operation on the plurality of symbols to generate a plurality of conjugate symbols;
multiplying the plurality of conjugate symbols by the echo-cancelled signal and a step size, respectively, to generate a plurality of coefficient adjustment values; and
adding the plurality of coefficient adjustment values to the plurality of coefficients, respectively, to generate the plurality of updated coefficients.
12 . The CFO estimation method according to claim 9 , wherein the selected symbol is a symbol received earliest among the plurality of symbols so as to cancel post-echo in the received signal.
13 . The CFO estimation method according to claim 9 , wherein the selected symbol is a next symbol of the received signal so as to cancel pre-echo in the received signal.