What cut-off of an output actually means in zero-forcing equalization?

Hello ,

i have a project and i was asked to equalize a channel( with zero forcing which i did like this :

i calculated the zero forcing equalizer fk for delay delta=5

where H is the toeplitz matrix of the channel h and e_delta is a vector where everything is 0 except the delay=5 which is 1

So , wrote this code :

kk=1
e_delta = zeros(1,4*K);
e_delta(kk+4) = 1;

L = length(h);
h_c=[h, zeros(1,L+6)];
h_r=[h(1),zeros(1,L+6)];

H=toeplitz(h_c,h_r); %toeplitz matrix

f = inv(H'*H)*H'*d'; %zero forcing equalizer

Next step: noise output through equalizer:

z=conv(y_noise,f); %y_noise through equalizer

The next question is asking to cut off the output of the equalizer and try to evaluate the input a of the channel . I dont understand what should i do in this part. Any help would be valuable.

Thank you.