Apparatus and method for performing channel estimations using non-linear filter
A channel estimation apparatus for WCDMA mobile communication terminal is disclosed. The channel estimation apparatus includes a moving average filter for calculating the average value of pilot signals; an interpolator for computing a tentative estimation value of channel variation by using linear interpolation algorithms based on the average value of pilot signal; a channel compensator for compensating a channel variable of the data signal delayed in a predetermined time based on the tentative estimation value of channel variation; a decision block unit for tentatively determining data signal based on the compensated data signals; a raw channel estimator for computing a raw channel estimation value based on the output signal of the decision block unit and the data signal delayed; and a non-linear filter for computing a final channel estimation value of channel variation based on the tentative estimation value of channel variation and the raw channel estimation value.
1. An apparatus for channel estimation by using a non-linear filter, comprising:
a multiplier for multiplying an input signal by a reference pilot signal;
a filter for calculating the average value of pilot signals;
an interpolator for computing a tentative estimation value of channel variation by using linear interpolation algorithms based on the average value of pilot signal;
a tentative channel estimation compensator for compensating a channel variable of the data signal delayed in a predetermined time based on the tentative estimation value of channel variation;
a decision block unit for tentatively determining a sign of data signal based on the compensated data signals;
a raw channel estimator for computing a raw channel estimation value based on the output signal of the decision block unit and the data signal delayed in a predetermined time; and
a non-linear filter for computing a final channel estimation value of channel variation based on the tentative estimation value of channel variation and the raw channel estimation value.
2. The apparatus as recited in claim 1 , wherein the non-linear filter includes a plurality of taps for computing the final estimation value of channel variation by combining output signals from the taps, wherein the non-linear filter is formed by one tap for providing a weight to the tentative estimation value of channel variation and other taps for providing a weight to the raw channel estimation value.
3. The apparatus as recited in claim 2 , wherein the weight is an inverse of the number of taps in the non-linear filter.
4. A method for making channel estimations using a non-linear filter, the method comprising the steps of:
a) calculating the average value of pilot signals;
b) computing a tentative estimation value of channel variation by using a linear interpolation algorithms;
c) compensating the channel variation of the data signal delayed in a predetermined time based on the tentative estimation value of channel variation;
d) tentatively determining a sign of data signal based on the compensated data signal;
e) computing a raw channel estimation value based on the data signal delayed in a predetermined time; and
f) computing the final channel estimation value of channel variation using a non-linear filter based on the tentative estimation value of channel variation and the raw channel estimation value.
5. The method as recited in claim 4 , wherein the non-linear filter includes a plurality of taps for computing the final estimation value of channel variation by combining output signals from the taps, wherein the non-linear filter is formed by one tap for providing a weight to the tentative estimation value of channel variation and other taps for providing a weight to the raw channel estimation value.
6. The method as recited in claim 5 , wherein the weight is an inverse of the number of taps in the non-linear filter.