基于平流层平台的空地一体化网络高效传输理论与方法研究

This Project addresses some theoretical and technological challenges arising from the rapid development of integrated stratospheric and terrestrial communications, especially stratospheric platform-based multi-tier heterogeneous wireless networks (HetNets), which would be a significant growth market for space-based Information and Communication Technology (ICT) industry. However, it faces a number of.challenging from both basic theory and key techniques. The main aims of this proposal are to advance the understanding of fundamentals of stratosphere-oriented HetNets, and to develop energy-efficient information theory and approaches under dynamic and large scale scenarios. The detailed objectives are as follows:.1) In order to deepen our understanding of energy-efficient transmission, after analyzing the variable efficiency metrics, we shall investigate spectrum, energy and space transmission efficiency of stratospheric HetNets. Based on network information theory, we shall develop mathematical models for efficiencies of stratospheric HetNets, and investigate their upper bounds in theory, and their relationship with the dynamic and large scale scenario..2) In order to approach the theoretical upper bounds of efficiencies in real communications, we shall investigate game-theoretic multi-dimensional resources optimization methods. Furthermore, to reduce the computational complexity of joint resource optimization algorithms to meet the dynamic requirements of stratospheric communications, distributed optimization and iterative searching will be used to approach the suboptimal solution. Moreover, Genetic algorithm and Particle Swarm Optimization algorithm will be introduced into the distributed optimization to get a rapid convergence..3) In order to solve the synchronous problem in multipoint-to-multipoint coordinated transmission, after considering the large and variable time and frequency offsets in stratospheric communications, we shall investigate joint preand post-compensation of time and frequency offsets associated with tolerant offsets.

针对基于平流层平台的空地一体化通信网络高动态、大尺度等挑战性问题，研究（空地）分层异构网络的高能效传输理论与方法。.1）分析频谱效率、能量效率与空间传输效率的内涵与外延；依托网络信息论与随机几何理论，探索分层异构网络的能效极限及其与高动态大尺度链路特性之间的内在联系。.2）通过资源与干扰联合优化，逼近网络容量与能效的理论极限。为了提高联合优化算法的收敛速度，以满足空地一体化通信的高动态需求，拟采用分步搜索、迭代优化，逼近次优解，同时引入遗传算法和粒子群优化算法，以实现分步优化的快速收敛。.3）针对空地一体化通信的时域、频域特性大尺度变化，拟采用基于可容忍同步误差限的收发联合补偿策略，解决多点多用户协同传输的时频同步难题。

针对基于平流层平台的空地一体化通信网络高动态、大尺度等挑战性问题，本项目研究了（空地）分层异构网络的高能效传输理论与方法：. 首先，提出了复杂异构网络的高效传输理论：1）针对空地一体化通信，将信息理论拓展到三维立体网络，分析了高动态大尺度条件下频谱效率、能量效率与空间传输效率的内涵与外延。2）依托网络信息论与随机几何理论，探索了分层异构网络的能效极限及其与网络拓扑结构、无线资源、干扰之间的内在联系，从而构建了高能效的空地一体化通信基础理论框架。3）通过控制平面与用户平面分离技术，建立了空地分层异构网络的高效传输理论模型，并引进非正交多址接入与端到端通信技术进一步提高了网络性能。. 其次，针对异构网络的多维资源与干扰联合管理问题：1）首先建立了空地一体化通信网络干扰分析模型，描述干扰的本质特征。采用基于多天线、协作多点对多用户的波束赋形技术，实现干扰排列。2）借助网络功能虚拟化，进行多维资源与干扰联合优化，构造基于能量效率的效用函数。该函数既具有严格的数学特征，又具有明确、直观的物理意义，能够逼近网络容量与能效的理论极限。3）为了提高联合优化算法的收敛速度，采用分步搜索、迭代优化方法，逼近次优解，同时引入遗传算法和粒子群优化算法，实现分步优化的快速收敛。. 最后，本项目研究了基于可容忍同步误差限的收发联合补偿：1）面对空地一体化通信的时域、频域特性大尺度变化，构建了协作多点对多用户传输的同步模型，定量描述了时频偏差与链路高动态大尺度特性的内在联系。2）将基于可容忍时频误差限的收发联合补偿策略建模为有约束的优化问题并进行求解。经过联合补偿后，各链路的剩余频偏都在可容忍范围内，满足同步要求，从而解决了多点多用户协同传输的时频同步难题。3）引入多智能体深度强化学习算法，攻克了联合优化的收敛问题以及在大尺度场景下的成功补偿概率问题。