channel estimation using LS

hi all,

i've to estimate the channel (i'm using random stream, just for simulation)

let X be the transmit symbol ( 128 taps length ) let Y be the recieved symbol ( 128 taps length ) H- is the channel (frequency domain)

when i use multiplication between X and H : Y=H.*X; I got the same channel by this code:

            Z = Y.*conj(X);
            F = (fft(eye(128))/sqrt(128));
            Fc = F([98:128 2:32],1:numChTaps); % numChTaps - is the delay spread length (num of channel taps)
            h_est = inv(Fc'*Fc)*Fc'*Z([34:64 66:96]);
            H_est=Fc*h_est;

but when i changed this multiplication between X and H by convolution between x and h i got wrong H_est

i can't find the mistake :/

[Vanita Pawar]

convolution between x and h must be a circular convolution and not the linear convolution.