Time：2026.07.30 10:30am
Location: Wireless Valley A1319
Speaker: Ke-Xin Li
Abstract：
Low-earth-orbit (LEO) satellite communications empowered by massive multiple-input multiple-output (MIMO) is expected to play a pivotal role in future global ubiquitous connectivity and 6G non-terrestrial networks. However, the practical deployment of massive MIMO in LEO systems faces two fundamental challenges: achieving high energy efficiency under stringent payload and power constraints, and ensuring reliable communications in the presence of intentional jamming and eavesdropping.
This talk presents two complementary physical-layer transmission techniques that address these challenges. First, an energy-efficient hybrid beamforming framework is introduced for uplink massive MIMO LEO satellite communications with multiple-antenna user terminals. By exploiting only long-term statistical channel state information, a tight closed-form upper bound on the energy efficiency is derived, enabling the joint design of hybrid precoders and receivers under practical fully-connected and partially-connected architectures. The proposed framework significantly reduces hardware cost and power consumption while maintaining near-optimal spectral efficiency. The second part of the talk focuses on highly reliable transmission for multi-satellite cooperative massive MIMO downlink communications in contested environments. Considering both jamming and eavesdropping attacks as well as the time-frequency asynchronous effects in multi-satellite systems, an ergodic sum secrecy rate optimization framework is developed. It is shown that single-stream transmission is optimal, which greatly simplifies the precoder design. Efficient algorithms are further proposed for cooperative precoding and jamming optimization, providing robust and secure communications against adversarial interference.
