BER Performance Analysis of OSTBC with 4-Antenna Configuration

This program simulates the Bit-Error-Rate (BER) performance of Orthogonal Space-Time Block Coding (OSTBC) with L=4 transmit antennas. The simulation models a frequency-flat Rayleigh block fading channel, a standard wireless communication scenario characterized by block-wise constant channel coefficients that change independently between blocks. The core implementation utilizes real orthogonal design with 1/2 code rate, meaning the OSTBC encoder maps two real symbols to four time slots across four antennas. The modulation scheme employs 16-QAM (Quadrature Amplitude Modulation) with Gray coding applied to minimize bit errors between adjacent constellation points. This configuration achieves a spectral efficiency of 2 bits per second per Hertz. The code structure includes: 1) Channel realization using complex Gaussian random variables for Rayleigh fading, 2) OSTBC encoding that distributes symbols across space-time dimensions following orthogonal design principles, 3) Maximum-likelihood decoding exploiting orthogonality for simplified symbol detection, and 4) BER calculation through comparative analysis between transmitted and received bit sequences across multiple channel realizations and SNR points. This framework enables comprehensive evaluation of OSTBC's fading mitigation capabilities in MIMO wireless systems.