Energy-Efficient Random Access for LEO Satellite-Assisted 6G Internet of Remote Things
Energy-Efficient Random Access for LEO Satellite-Assisted 6G Internet of Remote Things
复制标题
LEO 卫星辅助 6G 远程物联网的节能随机接入
DOI：
10.1109/jiot.2020.3030856
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发表时间：
2021-04-01
影响因子：
10.6
通讯作者：
Xiao, Pei
中科院分区：
文献类型：
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作者：
Zhen, Li;Bashir, Ali Kashif;Xiao, Pei
卫星通信系统有望在第六代视觉中实现各种远程互联网（IoT）应用程序发挥至关重要的作用。由于卫星环境的独特特征，该系统的主要挑战之一是适应物联网设备的大规模随机访问（RA）请求，同时最大程度地减少其能源消耗。在本文中，我们着重于对RA序言的可靠设计和检测，以有效提高高动态低轨道（LEO）方案的访问效率。为了避免其他信号开销和检测过程，通过在RA过程中串联单个根Zadoff-Chu（ZC）序列的连接和循环移动的复制品来构建一个长序列序列。此外，我们提出了一种基于可变化的差分互相关（LDCC）的新型冲动时间度量度量，该指标可免疫载体频率偏移（CFO），并能够减轻噪声对计时估计的影响。对拟议的度量的统计分析表明，增加相关长度显然可以促进输出信噪比的功率比率，而第一路检测阈值与噪声统计无关。仿真导致不同的LEO方案验证了所提出的方法的鲁棒性，以使其对严重的通道失真，并表明我们的方法可以在时间估计准确性，首次访问的成功概率和平均归一化访问能量方面实现显着的性能提高，与现有的RA方法相比。
Satellite communication system is expected to play a vital role for realizing various remote Internet-of-Things (IoT) applications in sixth-generation vision. Due to unique characteristics of satellite environment, one of the main challenges in this system is to accommodate massive random access (RA) requests of IoT devices while minimizing their energy consumptions. In this article, we focus on the reliable design and detection of RA preamble to effectively enhance the access efficiency in high-dynamic low-earth-orbit (LEO) scenarios. To avoid additional signaling overhead and detection process, a long preamble sequence is constructed by concatenating the conjugated and circularly shifted replicas of a single root Zadoff–Chu (ZC) sequence in RA procedure. Moreover, we propose a novel impulse-like timing metric based on length-alterable differential cross-correlation (LDCC), that is immune to carrier frequency offset (CFO) and capable of mitigating the impact of noise on timing estimation. Statistical analysis of the proposed metric reveals that increasing correlation length can obviously promote the output signal-to-noise power ratio, and the first-path detection threshold is independent of noise statistics. Simulation results in different LEO scenarios validate the robustness of the proposed method to severe channel distortion, and show that our method can achieve significant performance enhancement in terms of timing estimation accuracy, success probability of first access, and mean normalized access energy, compared with the existing RA methods.