AI 中文总结
本文提出一种用于LEO卫星的DSSS水印框架，将可恢复假名与密钥认证字段嵌入下行链路，可在多卫星干扰下实现被动检测验证，且对传统接收器透明。
AI 中文摘要
低轨（LEO）星座为定位、导航和授时（PNT）提供了密集的机会信号（SOP），无需专用导航基础设施。然而，当信标/导频组件较弱、多卫星信号重叠或接收器无法可靠识别产生观测值的卫星时，仅通过监听下行链路被动使用这些信号会很困难。本文提出一种低功耗直接序列扩频（DSSS）水印框架，该框架将可恢复的假名卫星标识符和密钥认证字段嵌入LEO下行链路信号中。该水印携带用于识别的公开卫星假名和基于密钥HMAC-SHA256的认证字段，支持无需完整下行链路解调的被动检测与验证。我们使用基于Starlink两行元素（TLE）的几何结构、多普勒效应和链路预算缩放，结合基于Sionna RT的本地传播，在多卫星仿真中评估该框架。结果表明，在共存卫星干扰下，该框架可实现候选卫星检测、公开ID恢复和密钥验证，且对仿真信标/导频及主下行链路组件的扰动有限。该框架面向未来支持发射器的LEO系统，同时对不处理低功耗水印的传统接收器保持透明。
英文摘要
Low-Earth-orbit (LEO) constellations offer dense signals of opportunity (SOP) for positioning, navigation, and timing (PNT) without dedicated navigation infrastructure. However, using these signals passively, by only listening to the downlink, is difficult when beacon/pilot components are weak, signals from multiple satellites overlap, or the receiver cannot reliably identify which satellite generated a given observable. This paper proposes a low-power direct-sequence spread-spectrum (DSSS) watermarking framework that embeds a recoverable pseudonymous satellite identifier and keyed authentication field into a LEO downlink signal. The watermark carries a public satellite pseudonym for identification and a keyed HMAC-SHA256-based authentication field for authorized verification, enabling passive detection and verification without full downlink demodulation. We evaluate the framework in a multi-satellite simulation using Starlink two-line-element (TLE)-derived geometry, Doppler, and link-budget scaling with Sionna RT-based local propagation. The results demonstrate candidate-satellite detection, public-ID recovery, and keyed verification under co-observed satellite interference, with limited perturbation to the simulated beacon/pilot and primary downlink components. The framework targets future transmitter-enabled LEO systems while remaining transparent to legacy receivers that do not process the low-power watermark.
Comments6 pages, 7 figures. Accepted to the 2026 IEEE Military Communications Conference (MILCOM 2026)
