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 quickly, robustly, and cost-efficiently 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 providing 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 layer, medium access control (MAC) layer, network layer, and transport layer of NSIN for achieving efficient transmission over NSIN are overviewed. Finally, we outline some open issues and promising directions of NSIN 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）构成，是一种能够快速、稳健且经济高效地提供感知与通信服务的新体制。受制造、材料、通信、电子与控制领域创新与突破的推动，NSIN已成为第六代移动通信系统的重要组成部分。本文旨在以前瞻性、比较性和技术演进的视角，探讨并阐述NSIN在信道建模、组网与传输领域的最新进展。文中重点剖析了NSIN的特性，展示了其典型应用场景，并数学分析了空中平台的不稳定运动对不同结构机载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，以及HAP与UAV信道建模间的显著差异。从网络部署、切换管理及网络管理三个维度，全面综述了NSIN的组网技术。此外，还概述了NSIN物理层、媒体接入控制（MAC）层、网络层与传输层中实现高效传输的潜在技术与通信协议。最后，本文梳理了NSIN未来研究中值得关注的关键问题与潜在方向，并探讨了相应挑战。