simulate a communication channnel in MATLAB

DON'T SHOUT: Using all capitals is considered shouting on the internet, and rude (using all lower case is considered childish). Use proper capitalisation if you want to be taken seriously.
Urgency deleted: It may be urgent to you, but it isn't to us. All that your stressing the urgency does is to make us think you have left it too late, and want us to do it for you. This annoys some people, and can slow a response.