Dr. Aijun Song: Underwater Communications and Research

Sounding the Depths: Dr. Aijun Song and the Frontier of Underwater Acoustic Communications

When we think about global connectivity, our minds naturally drift to the skies—to satellites orbiting the Earth, vast webs of fiber-optic cables crossing ocean floors, and cellular towers blanketing our cities. Yet, a massive portion of our planet remains virtually invisible to traditional radio frequency (RF) wireless signals: the deep blue sea. Because electromagnetic waves struggle to propagate through water, underwater communication has historically been a formidable engineering bottleneck.

Enter Dr. Aijun Song, a leading researcher and professor in electrical and computer engineering whose pioneering work is transforming how we talk to, navigate, and monitor the underwater world. Through groundbreaking advancements in underwater acoustic communications (UAC), intelligent surfaces, and autonomous marine networking, Dr. Song is helping humanity unlock the secrets of Earth’s final terrestrial frontier.

Bridging the Acoustic Gap

Dr. Song—a faculty member at the University of Alabama—has dedicated his career to solving the unique physics of sub-surface communication. Unlike terrestrial Wi-Fi or 5G, which rely on electromagnetic spectrums, underwater systems must rely on sound. Sound waves travel efficiently through water, but the underwater acoustic channel is notoriously harsh. It suffers from severe multipath propagation, high ambient noise, limited bandwidth, and significant Doppler shifts caused by water currents and moving nodes.

To overcome these hurdles, Dr. Song’s research focuses on robust physical-layer designs, advanced signal processing, and multi-input, multi-output (MIMO) systems. His work addresses how data can be reliably transmitted over long distances without succumbing to the distorting effects of dynamic marine environments.

Pioneering Underwater Acoustic Reconfigurable Intelligent Surfaces (UA-RIS)

One of Dr. Song’s most exciting recent contributions to ocean engineering is the development of Underwater Acoustic Reconfigurable Intelligent Surfaces (UA-RIS).

Traditionally, extending the range of underwater acoustic links required boosting transmitter power, which not only drains battery life on autonomous underwater vehicles (AUVs) but also increases noise pollution for marine life like dolphins and whales. Dr. Song and his collaborators introduced UA-RIS technology—using arrays of smart acoustic reflectors that can precisely control the amplitude and phase of reflected sound waves.

• Precise Beam Steering: By manipulating how sound bounces off these intelligent surfaces, signals can be tightly steered toward a targeted receiver rather than scattering uselessly.
• Extended Range & Eco-Friendly Operation: Field tests in lakes and deep water have demonstrated that deploying UA-RIS can extend communication ranges by tens of percents while significantly boosting the signal-to-noise ratio (SNR). Crucially, it allows systems to maintain high data rates while reducing overall acoustic emissions, protecting marine ecosystems from human-made noise interference.

Powering the Internet of Underwater Things (IoUT)

Dr. Song’s research extends far beyond individual links; it lays the structural groundwork for the Internet of Underwater Things (IoUT) and collaborative Autonomous Underwater Vehicle (AUV) networks.

Modern oceanography, defense, environmental monitoring, and offshore industry operations increasingly rely on fleets of autonomous robots working together. For these robots to coordinate paths, share sensor data, and map the ocean floor in real-time, they need reliable multi-hop networking protocols. Dr. Song’s work integrating software-defined acoustic modems with vehicle autonomy architectures (such as MOOS-IvP) has provided vital frameworks for turning isolated sub-surface drones into cohesive, communicating mobile networks.

Looking Ahead

As humanity looks more toward the “blue economy”—sustainable ocean resource management, climate change tracking, and deep-sea exploration—the demand for high-speed, reliable underwater data infrastructure has never been higher.