STBC Encoding in OFDM Systems with MATLAB Implementation

In OFDM systems, STBC encoding combined with QPSK modulation can be employed for signal transmission. This MATLAB program implements such encoding and modulation schemes. The code allows configuration of OFDM parameters including the number of subcarriers, carrier spacing, and symbol duration. It generates data sequences for transmission and applies STBC encoding to enhance spatial diversity. The encoded data is then mapped to complex signal points using QPSK modulation, which implements Gray coding for optimal bit error performance. Finally, the modulated signals are distributed across multiple subcarriers using OFDM technology through IFFT transformation and cyclic prefix insertion. This implementation demonstrates key functions like stbc_encode() for Alamouti coding, qpsk_modulator() for constellation mapping, and ofdm_modulator() for multi-carrier synthesis, providing insights into the principles and applications of STBC coding and QPSK modulation in OFDM systems.