卫星物联网混合随机接入技术

在卫星物联网(IoT)场景中，随着终端数量不断增加，频谱资源日益紧张。传统的随机接入技术频谱利用率较低，使得传统随机接入协议不适用于未来卫星IoT的高并发业务需求。同时，卫星通信链路长，开放性强，难以保证特种终端信号的安全性。对此，本文提出一种适用于卫星IoT的混合随机接入方案。该方案引入重叠传输的容量提升与安全性优势，利用扩频码对瞬时功率谱密度的控制能力，构造功率域非正交接入条件，并通过接收端的迭代分离实现稳健接收。对本文所提方案的吞吐量性能进行闭式解推导分析与计算机仿真，结果表明，与传统的随机接入协议相比，所提方案可提高系统吞吐量。同时，相较于常用信号隐藏方法，所提方法利用常规接入数据包的功率优势，强化了波形隐藏效果，提升了特种信息接入的安全性。

Hybrid random access technology of satellite Internet of Things

In the satellite Internet of Things(IoT) scenario, as the number of terminals continues to increase, the spectrum resources are of shortage increasingly, and the traditional random access technology has low spectrum utilization, making the traditional random access protocol unsuitable for the high concurrent service requirements of the future satellite IoT. At the same time, satellite communication links are long and open, making it difficult to guarantee the security of special terminal signals. This paper proposes a hybrid random access scheme suitable for satellite Internet of Things. This scheme introduces the capacity improvement and security advantages of overlapping transmission, utilizes the ability of spreading code to control the instantaneous power spectral density, constructs non-orthogonal access conditions in the power domain, and achieves robust reception through iterative separation at the receiving end. The derivation analysis and computer simulation of the throughput performance of the proposed scheme are carried out. The simulation results show that the proposed scheme can improve the system throughput compared with the traditional random access protocol. At the same time, compared with common signal concealment methods, the proposed method utilizes the power advantage of conventional access data packets to strengthen the waveform concealment effect and improve the security of special information access.