0.4 Receiver

Decoding the transmission

Since the receiver has full knowledge of all the steps taken to transmit, the reception process is the exact inverse of transmission. The only difference is the addition of the channel equalization described in the previous part. To get back the information we originally sent, we simply:

• Take the FFT of the reception and divide it by the FFT of the impulse response. Then iFFT it back.
• Remove the cyclic prefix
• Take the Fourier Transform
• Demirror the vector
• Approximate each received value to nearest point in constellation and map them back to the original bit sequences. See figure below for example in 4 bit approximation.
• Convert the binary series back to ascii letter equivalents.

Approximation of constellation map

Please see the block diagram below. It summarizes the reception process.

Receive block diagram