OFDM Downlink Simulation

When performing OFDM downlink simulation, the following steps are executed for data transmission: 1. Generate random binary data for transmission using random number generators or predefined bit sequences. 2. Perform digital modulation (BPSK, QPSK, or QAM) to convert the data bits into complex symbols representing the signal constellation points. 3. Implement serial-to-parallel conversion to distribute the modulated symbols across multiple subcarriers, preparing them for OFDM processing. 4. Apply Inverse Fast Fourier Transform (IFFT) operation. The implementation utilizes conjugate symmetric vectors to ensure real-valued time-domain signals, simplifying computational complexity. 5. Add cyclic prefix by copying the end portion of each OFDM symbol to its beginning. This crucial step mitigates inter-symbol interference (ISI) caused by multipath propagation. 6. Perform parallel-to-serial conversion to combine the OFDM symbols into a continuous time-domain signal stream for transmission. 7. Apply transmit filtering (typically using raised cosine or root raised cosine filters) to limit bandwidth and reduce out-of-band emissions before signal output. 8. Add channel noise modeled as Additive White Gaussian Noise (AWGN) to simulate realistic wireless channel conditions with specified signal-to-noise ratio (SNR). 9. At the receiver side, implement serial-to-parallel conversion to reconstruct the parallel OFDM symbol structure for processing. 10. Remove the cyclic prefix from each received OFDM symbol to eliminate the guard interval and extract the core symbol data. 11. Perform Fast Fourier Transform (FFT) operation to convert the time-domain signal back to the frequency domain, recovering the original subcarrier modulation. 12. Execute signal demodulation by mapping the received constellation points back to binary data using decision boundaries based on the modulation scheme. 13. Calculate Bit Error Rate (BER) by comparing the transmitted and received bit sequences to evaluate transmission accuracy and system performance under various channel conditions.