用清晰度加权分配比特,让卫星传更多有用图像。
Clear-Weighted Bit Allocation for Satellite Downlinks

- 神经编码器按清晰概率加权重建损失,把云区的比特转给清晰地面。
- 在相同清晰度下,比现有方法少用47.8%的传输字节。
- 无需上行云图,适合资源受限的卫星系统实时调度。
地球观测卫星拍摄的图像超过间歇性地面通信能力可传输的数量。当前系统通过云检测器阈值丢弃帧或瓦片,并对剩余内容使用固定编码器压缩。在专家标注的图像上,这些规则导致超过五分之一的清晰像素被误删,主要源于检测器误报。本文训练一种神经编码器,采用清晰概率加权的重建损失,将原本分配给云区的码流重新分配给清晰地表区域,无需在星上生成或传输云图。每幅图像编码为可恢复的基础层和依赖层,清晰内容由编码器特征估计。每次通信接触时,基于估计的清晰内容、未完成字节数、截止时间余量及累积截止压力,动态排序到达层。调度器兼顾基础层与计算层截止时间,控制残留字节存储,支持中断包恢复。我们使用真实熵编码字节、轨道推导的可中断通信容量、以及资源受限嵌入式加速器上的实际服务时间与能耗评估端到端流程。清晰加权编码器在保持清晰区域质量的前提下,相比学习型压缩基线最多减少47.8%字节。优化编码器耗时能耗低于一次云检测器运行。相较于固定两阶段服务,在同一数据流上,本调度器使中断联合组的截止时间可用清晰内容交付量提升超一倍,达到认证理想调度器上界83.6%,且优于回放参考排序。
原文摘要 · Abstract (English)
Earth-observation satellites capture more imagery than intermittent ground contacts can transmit. Onboard systems threshold a cloud detector, discard frames or tiles, and compress the survivors with a fixed codec. On expert-labeled imagery, these rules remove more than one-fifth of clear pixels, primarily through detector false positives. We train a neural codec with a clear-probability-weighted reconstruction loss, reallocating coded bytes from clouds to clear ground without requiring or transmitting a cloud map onboard. Each capture is encoded into a resumable base layer and a dependent refinement layer, while clear content is estimated from features produced by the encoder. At each contact, we causally rank arrived layers using estimated clear content, unfinished bytes, deadline slack, and aggregate deadline pressure. The scheduler serves base and computational deadlines, bounds stored residual bytes, and resumes interrupted packets. We evaluate the onboard-to-downlink pipeline using real entropy-coded bytes, orbit-derived interruptible contact capacities, and measured service time and energy on resource-constrained embedded accelerators. Clear-weighted codecs require up to 47.8\% fewer bytes than learned-compression baselines at matched clear-region quality. The optimized encoder consumes less time and energy than one pass of the cloud detector used by the frame-discard rules. Relative to fixed two-stage service on the same streams, our scheduler more than doubles deadline-full clear-content delivery for the interrupted combined cohort, reaches 83.6\% of a certified clairvoyant upper bound, and exceeds replayed reference orders in deadline-usable delivery.
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