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digital system with rayleigh channel in simulink

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Aug 25, 2009
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rayleigh channel

Hello folks, just discovered this valuable forum through google.

I searched the forum regarding Rayleigh channel modeling and all I found was matlab m files, so I'm chancing it and hope you might be able to help.

I'm currently designing a simulink model for adaptive digital audio transmission, in an AWGN channel it works fine, but I have trouble when I introduce a Rayleigh channel.

In a basic system with 16-QAM transmitting over an AWGN and rayleigh channel I used a LMS equalizer assuming the Rx can generate a perfect copy of the message, it produces a waterfall untill it reaches a point of an 'error floor', once convolutional coding was introduced the BER was around ~0.5. In the example a code rate of 1/4 used.
I eventually want to add OFDM for the multiple levels, but I need to get past this stage first to have a analytical decision.

I checked the MATLAB demo section and found a military NATO comm system using PSK . Tx'ing over a AWGN and Rayleigh channel. From what I understood is that the Tx compared the signal to a preknown signal and transmitted the unknown data and then did something similar at the receiver after equalization.

from reading papers about rayleigh channels I found one mentioning the use of an automatic gain controller (AGC) for use in the pilots. As my system has no pilots yet its not much use.
Would the introduction of OFDM and evaluating the pilots produce a typical BER?

Any help would be greatly appreciated.


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