Experimental Demonstration of OFDM-Alamouti Space-Time Block Code for Millimeter-Wave Wireless Transmission

With the increasing demand for high data rates and high-reliability wireless communication, millimeter-wave (mmWave) communication has become an important technological direction for realizing future high-speed wireless interconnection due to its ability to provide ultra-wideband transmission bandwidth. However, mmWave signals are susceptible to multipath fading, rain attenuation, and phase distortion in complex communication environments, leading to a decrease in link reliability. To mitigate these effects, transmitter diversity technology provides an effective method to improve the robustness of high-frequency communication systems. This paper proposes and investigates a mmWave wireless communication system that integrates orthogonal frequency-division multiplexing (OFDM) with Alamouti space-time block coding (STBC) to enhance link robustness and bit error rate performance in prospective 6G scenarios. The system utilizes the frequency-selective fading resistance of OFDM and the spatial diversity gain of Alamouti-STBC to achieve efficient and reliable transmission over 30m in a dual-transmitter-one-receiver architecture. The rain attenuation model is constructed according to the ITU-R standard to simulate the mmWave propagation characteristics under a rainfall intensity of 20 mm/hr. Experimental results show that the proposed OFDM-Alamouti-STBC scheme exhibits a lower bit error rate and better link stability under conditions of rain attenuation and multipath effects. The research results verify that the effective combination of OFDM and Alamouti-STBC can significantly mitigate millimeter-Wave signal fading, providing a highly reliable transmission scheme with practical value for future 6G mmWave broadband wireless communication systems.