This example estimates the channel response for an OFDM signal filtered through a 2-by-4 MIMO channel, and then uses the channel response to apply OFDM equalization to the received OFDM-demodulated signal.
Define simulation variables.
Configure OFDM subcarriers.
Generate an array of data symbols, QAM-modulate the symbols, and then OFDM-modulate the QAM-modulated symbols.
Filter the OFDM-modulated signal through a MIMO channel and AWGN.
Use channel path gains returned by the MIMO channel object, and the path filters and timing offset returned by the info
object function, to estimate the OFDM channel response.
To use the OFDM channel response when equalizing the OFDM-demodulated signal, you must reshape the -by--by--by- array to an -by--by- array. Before demodulating the OFDM signal, account for the timing offset and symbol offset, remove the initial samples, and then pad with zeros to keep the signal length unchanged.
OFDM-demodulate and equalize the received signal. Show the received OFDM-demodulated symbols (rxSym
) and the equalized OFDM-demodulated symbols (eqSym
). The constellation of the OFDM-demodulated symbols before equalization does not resemble the QAM constellation. After equalization, the constellation points overlay the reference constellation.