MMSE equalizer

I have written a code for estimation and MMSE equalization for OFDM system. When I apply equalization at the receiver the BER increases. Let me the problem in my code. Code is attached. thanks

clc
close all
clear all

H = comm.QPSKModulator('BitInput',true);
Hdemod = comm.QPSKDemodulator('BitOutput',true);
% hScope = commscope.ScatterPlot;
% hScope.Constellation = [0.7071+0.7071i -0.7071+0.7071i -0.7071-0.7071i 0.7071-0.7071i];
% hScope.SamplesPerSymbol = 1;

n=16;    %no of random data...
r_data = randint(n,1); %random numbers generator...
data_qpsk=[];
data_qpsk = step(H,r_data); %Data converted in QPSK symbols...

d1=data_qpsk(1);
d5=data_qpsk(5);

data_qpsk(1) = 0.7071+0.7071i; % adding two pilots at location 1 and 5.
data_qpsk(5) = 0.7071+0.7071i;
% update(hScope, data_qpsk);

dawgn=awgn(data_qpsk,0); % Adding white Gaussian Noise

est(1)=dawgn(1);
est(2)=dawgn(5);

% MMSE starts here......
des=[0.7071+0.7071i 0.7071+0.7071i];% desired data symbols
rec=[est(1) est(2)]; % received data symbols...
z=filter([1 0 0 0 0 0 0 0],[1],rec);
Rxx=xcorr(rec);
Rxz=xcorr(des,z);
x=toeplitz([Rxx zeros(1,5)],zeros(1,8))
cof=x\([Rxz zeros(1,5)].'); % coefficients for MMSE equalizer...

det1=filter(cof,[1],dawgn);
det1

for i=1:8
det(i)=filter(cof,[1],dawgn(i));
end
det.'

% update(hScope, det);

[Daniel Shub]

Can you explain what the problem is?

Answer 1

[Sundus Naseer]

??? Undefined variable "comm" or class "comm.QPSKModulator".

Error in ==> mmse at 5 H = comm.QPSKModulator('BitInput',true);

Answer 2

[Sundus Naseer]

:P :P

Answer 3

[Honglei Chen]

It seems you don't have Communication System Toolbox correctly installed. What is your result of the following command?

>>ver