Probabilistic constellation shaping controls interference in sensing and communication systems
How Does Probabilistic Constellation Shaping Control Ranging Sidelobe Levels in ISAC?
Information Theory
Summary
Systems that send data and sense their environment at the same time can experience interference that makes sensing less accurate. The authors explain a way to carefully shape how signals are sent so that the interference patterns (called sidelobes) are better controlled on a per-codeword basis, improving sensing reliability. They also show that this approach works especially well with a signal technique called OFDM. Their methods allow sending data more efficiently while keeping sensing interference low.
What this means in practice
- •For wireless communication engineers: Design data signals in OFDM-based systems to precisely control sidelobe interference and improve sensing accuracy.
- •For radar system developers: Implement PCS strategies compatible with PAS to increase data rates while maintaining strict sensing interference limits in integrated sensing and communication devices.
Authors
Zexuan Jing, Yifeng Xiong, Fan Liu, Xuehua Li, Jianhua Zhang
Abstract
Probabilistic constellation shaping (PCS), originally designed to fill the gap between finite uniform constellations and continuous capacity-achieving input distributions, has recently emerged as a central tool in adjusting the expected integrated sidelobe level (EISL) in integrated sensing and communication (ISAC). In this paper, we show that PCS goes beyond EISL: A large class of PCS methods, termed as type-based PCS, are capable of providing precise control over codeword-wise integrated sidelobe level ratio (ISLR) for systems employing orthogonal frequency division multiplexing (OFDM), thus yielding a stronger sensing performance guarantee than EISL control. We further show that OFDM is almost the only unitary modulation basis whose codeword-wise ISLR can be precisely controlled by type-based PCS. Based upon the analytical results, practical type-based PCS methods compatible with the probabilistic amplitude shaping (PAS) framework are conceived, which achieve higher communication rates than existing ISAC-oriented PCS methods under identical ISLR constraints.