| 摘要: |
| 在面向卫星物联网的免授权随机接入（Grant-free Random Access,GFRA）系统中，受大规模连接和设备随机激活的影响，前导碰撞成为用户接入性能提升的主要制约因素。鉴于此，借助正交与非正交序列在前导检测和冲突抑制方面的各自优势，提出一种基于混合ZC(Zadoff-Chu)序列的大容量前导设计和检测方法。该方法利用正交ZC序列与其循环移位映射的不同根ZC序列级联来构建前导序列，并采用一种基于假设检验的两阶段干扰消除活跃用户检测算法，以确保大规模接入场景下的高精度用户识别。此外，对所提前导结构进行扩展，将相位旋转因子与多段非正交序列相结合，在不增加峰均比的前提下进一步扩大前导集容量。所提方法较现有复合和正交前导方法具有显著改善的多用户识别性能，在相同活跃用户下，成功检测概率最大提升约30.3%。 |
| 关键词: 卫星物联网 免授权随机接入(GFRA) 活跃用户检测 级联映射前导 ZC序列 |
| DOI：10.20079/j.issn.1001-893x.241113001 |
|
| 基金项目:国家自然科学基金资助项目（61901370）；陕西省创新能力支撑计划（2023KJXX-062）；陕西省重点研发计划（2024GX-YBXM-064,2022ZDLGY05-08）；陕西省教育厅重点项目（23JS057） |
|
| A Large-capacity GFRA Preamble Design Scheme Based on Concatenated Mapping ZC Sequences |
| ZHEN Li,MA Mingke,PEI Chenchen,DONG Ping,WANG Wenjing,QIN Hao |
| (1. Shaanxi Key Laboratory of Information Communication Network and Security,Xi’an University of Posts and Telecommunications,Xi’an 710121,China;2.State Key Laboratory of Integrated Services Networks,Xidian University,Xi’an 710071,China) |
| Abstract: |
| In grant-free random access(GFRA) systems for satellite-based Internet of Things scenarios,preamble collision has become a major factor limiting the improvement of user access performance,due to the impact of massive connections and random device activation.To address this issue,a large-capacity preamble sequence design and detection scheme based on hybrid Zadoff-Chu(ZC) sequences is proposed,by leveraging the advantages of orthogonal and non-orthogonal sequences in preamble detection and collision suppression.Specifically,the preamble sequence is first constructed by concatenating orthogonal ZC sequences with different root ZC sequences mapped through cyclic shifting.Then,a two-stage interference-cancellation active user detection algorithm based on hypothesis testing is employed to achieve accurate user identification in massive access scenarios.In addition,the preamble structure is extended by combining phase rotation factors with multi-segment non-orthogonal sequences,so as to further enlarge the capacity of the preamble set without increasing the peak-to-average power ratio.The proposed scheme exhibits significantly improved multi-user identification performance compared with existing composite and orthogonal preamble schemes.Under the same number of active users,the probability of successful detection is increased by approximately 30.3% at most. |
| Key words: satellite Internet of Things grant-free random access(GFRA) active user detection concatenated mapping preambles ZC sequences |
