The document discusses simulation and performance estimation of BPSK modulation in Rayleigh fading channels using three diversity combining techniques: selection combining (SC), maximal ratio combining (MRC), and equal gain combining (EGC). It provides mathematical analysis of how these techniques calculate bit error rate (BER) and compares their performance. The key findings are that MRC achieves the best performance with lowest required SNR, followed by EGC, while SC requires the highest SNR to achieve a given BER. Performance is improved by increasing the number of diversity branches for all techniques.