Robotics & Embodied AI
Simulations show an optimization method reduced path interference in systems that use a reconfigurable intelligent surface for sensing and communication
In a 2025 paper in IEEE Journal on Selected Areas in Communications, a peer-reviewed journal, researchers at New York University Abu Dhabi and New York University modeled a base station that communicates with a user while a passive radar senses targets using the same downlink signals. A reconfigurable intelligent surface (RIS), a panel that steers radio waves by changing its phase shifts, assists both tasks. The surface also creates extra signal paths, which the authors call path interference, and those paths can flood the passive radar with too much power. The researchers designed an optimization method that adjusts the RIS phase shifts, the radar's space-time beamforming, and the transmit signal pattern to reduce that path interference. In simulations, the authors report their solver was effective compared with benchmark methods.
What problem did the paper address?
The paper studies a conflict in a combined communication and radar system. A base station serves a user, and a passive radar uses the base station's downlink signals to sense targets. When a reconfigurable intelligent surface helps both jobs, it introduces interfering paths. The authors divide that interference into direct path interference (DPI) and reflected path interference (RPI), which together they call path interference (PI). Those paths can deliver unnecessarily high power to the passive radar and overwhelm it.
How did the researchers reduce the interference?
They formulated an optimization problem that keeps the communication and sensing tasks running while cutting path interference power. Because the problem is non-convex, meaning it has many local solutions, the researchers split it into a hard non-convex part and an easier convex part with a block-cyclic coordinate descent method. A Riemannian conjugate gradient method, a specialized optimization routine, computes the phase shifts for the RIS and the passive radar's space-time beamforming in each step, and an off-the-shelf solver handles the convex part. In simulations, the authors report the method was effective compared with benchmark methods.
Frequently asked questions
What is integrated sensing and communication?
Integrated sensing and communication (ISAC) combines wireless communication and radar sensing in the same system and often the same signals. In this paper, a base station communicates with a user while a passive radar uses the downlink signals to sense targets.
What is a reconfigurable intelligent surface?
A reconfigurable intelligent surface is a panel that can steer radio waves by changing its phase shifts. In this paper, the surface assists both the communication link and the sensing task, but it also adds path interference.
What did the simulation results show?
The simulations show the proposed solver was effective compared with benchmarking methods. The abstract reports this comparison only for simulations, not for a physical system.
Limits and what's next
This is one simulation study. The abstract describes a modeled system scenario and simulation results, not a physical test. It reports no independent replication or external validation. The findings rest on the simulations and benchmark comparisons described in the abstract.
Source: Ahmad Bazzi and Marwa Chafii, “Low Dynamic Range for RIS-Aided Bistatic Integrated Sensing and Communication,” IEEE Journal on Selected Areas in Communications, 2025.