低轨卫星物联网随机码分多址技术  

Random Code Channel Access Technology for Low-Orbit Satellite IoT

作　　者：邱琳 陈舒怡 孟维晓[1] QIU Lin;CHEN Shuyi;MENG Weixiao(Communication Research Center,Harbin Institute of Technology,Harbin 150001,China)

机构地区：[1]哈尔滨工业大学通信技术研究所,黑龙江哈尔滨150001

出　　处：《无线电通信技术》2021年第5期549-556,共8页Radio Communications Technology

基　　金：国家自然科学基金项目(61871155)。

摘　　要：作为国家导向的数字新基建,卫星物联网可有效地对地面蜂窝网络进行补充,具有覆盖范围广、受环境条件影响小、较高的可靠性与稳定性等特点。传统的接入方式按照不同的网络层次可分为物理层的多址接入技术及MAC层的随机接入技术。然而分析现有的接入技术,针对卫星物联网这一特定场景的研究鲜有提及。在现有的ALOHA随机接入技术基础上,结合码分多址CDMA的思想,给出了基于码道划分的非授权随机接入方式,并针对该方式下的碰撞包丢弃与碰撞包重传两种方式下的系统性能进行仿真,分析了吞吐量、成功传输概率、平均重传时延及碰撞概率等几个主要参数指标。仿真结果显示,多码道随机接入情况下,系统的碰撞概率及吞吐量性能明显提升,更适用于大规模接入的卫星物联网。进一步对卫星物联网采用授权与免授权混合模式下的系统性能进行了理论及仿真分析,给出了系统吞吐量最大及碰撞概率最低时的码道数目理论值。As a nationally-oriented digital new infrastructure,satellite IoT can effectively supplement terrestrial cellular networks.It has the characteristics of wide coverage,low impact from environmental conditions,and high reliability and stability.Traditional access methods can be divided into physical layer multiple access technology and MAC layer random access technology according to different network levels.However,existing access technology has not targeted specific scenarios of satellite Internet of Things.On the basis of the existing ALOHA random access technology,combined with the idea of code division multiple access CDMA,a grant-free random access method based on code channel division is given.And collision packet discarding and collision packet retransmission in this method are also proposed.System performance under the two modes is simulated,and several main parameters such as throughput,successful transmission probability,average retransmission delay and collision probability are analyzed.Final results show that the collision probability and throughput performance of the system are significantly improved in the case of multi-code random access,which is more suitable for large-scale satellite Internet of Things.Further theoretical and simulation analysis is performed on the system performance of the satellite Internet of Things under the hybrid mode of grant-based and grant-free.And the theoretical value of the number of code channels when the system throughput is the largest and the collision probability is the lowest is given.

关 键 词：卫星物联网 随机接入 码道正交 碰撞概率 

分 类 号：TN919.23[电子电信—通信与信息系统]