Near-space information networks (NSIN) composed of high-altitude platforms (HAPs), high- and low-altitude unmanned aerial vehicles (UAVs) are a new regime for providing quick, robust, and cost-efficient sensing and communication services. Precipitated by innovations and breakthroughs in manufacturing, materials, communications, electronics, and control technologies, NSIN have emerged as an essential component of the emerging sixth-generation of mobile communication systems. This article aims at {presenting some critical issues and design proposals in our actual NSIN and} discussing the latest advances in NSIN in the research areas of channel modeling, networking, and transmission from a forward-looking, comparative, and technological evolutionary perspective. In this article, we highlight the characteristics of NSIN and present the promising use-cases of NSIN. The impact of airborne platforms' unstable movements on the phase delays of onboard antenna arrays with diverse structures is mathematically analyzed. The recent advancements in HAP channel modeling are elaborated on, along with the significant differences between HAP and UAV channel modeling. A comprehensive review of the networking technologies of NSIN in network deployment, handoff management, and network management aspects is provided. Besides, the promising technologies and communication protocols of the physical (PHY) layer, medium access control (MAC) layer, network layer, and transport layer of NSINs for achieving efficient transmission over NSINs are overviewed, {and we have conducted experiments with our actual NSIN to verify the performance of some techniques}. Finally, we outline some open issues and promising directions of NSINs deserved for future study and discuss the corresponding challenges.

翻译：临近空间信息网络（NSIN）由高空平台（HAP）、高低空无人机（UAV）组成，是提供快速、稳健且低成本感知与通信服务的新体制。受制造、材料、通信、电子及控制技术的创新与突破推动，NSIN已成为新兴第六代移动通信系统的重要组成部分。本文旨在从前瞻性、比较性与技术演进视角，探讨NSIN在实际应用中的关键问题与设计方案，并阐述信道建模、组网与传输领域的最新进展。我们重点分析了NSIN的特性及潜在应用场景，数学解析了机载平台不稳定运动对不同结构天线阵列相位延迟的影响，详细阐述了HAP信道建模的最新进展及其与UAV信道建模的显著差异。从网络部署、切换管理和网络管理三方面全面综述了NSIN的组网技术，并系统概括了NSIN物理层、媒体接入控制层、网络层和传输层中实现高效传输的潜在技术与通信协议，同时通过实际NSIN实验验证了部分技术性能。最后，我们提出了NSIN未来研究中值得探索的开放性问题与前沿方向，并讨论了相应挑战。