Energy-Efficient mmWave Transmission: Over-the-Air-Modulation (OTAM) System Using Moment Analysis Framework

Millimeter wave (mmWave) technology promises unprecedented capacity and ultra-low latency for wireless communications. However, mmWave systems confront challenges, including high costs, power consumption, and accurate carrier synchronization, significantly limiting mmWave-based applications. The emerging over-the-air modulation (OTAM) technique has recently demonstrated cost-effective and low-power mmWave communication by utilizing channel attenuation difference characteristics to achieve an ASK-like modulation effect. Despite these advancements, the wireless beam modulation (WBM) system based on the OTAM technique suffers from nonlinear interference caused by random phase offsets when supporting multinode spatial division multiplexing (SDM) access. To address the challenges, we propose a moment-based analysis (MBA) framework to reduce carrier synchronization requirements, enabling the WBM system to linearize nonlinear spatial interference under coarse carrier synchronization. Within the MBA framework, we further develop a moment-based interference cancellation (MBML-IC) algorithm based on the maximum likelihood criterion. The MBML-IC algorithm eliminates interference in the energy domain, thereby supporting multi-node SDM access for the WBM system. Simulation experiments validate the performance improvements regarding the system bit error rate (BER). Besides, the proposed MBA framework and MBML-IC algorithm empower the WBM system to employ lower-precision, cost-effective, and low-power mmWave components, enhancing energy efficiency.