摘要
大规模无授权接入是海量物联网需要解决的瓶颈问题之一,技术上需要进行活跃用户检测以及相应的信号解调。目前,大部分方案都假设接入用户是时隙同步的。考虑异步无授权随机接入方案,由于缺乏严格的上行(Uplink,UL)定时控制过程,基站接收到的不同活跃用户的信号是异步的,但时间偏差控制在一定范围之内。针对异步无授权接入场景下的大规模机器通信中的活跃用户检测及信号恢复,提出一种低复杂度的贪婪算法。该算法首先对活跃用户中最强的用户及其延时进行估计,然后利用BCD算法进行信道估计和信号解调,在此基础上,在接收信号中消除当前已估计出的最强活跃用户的信号成分,从而算法转入下一个活跃用户的检测和信号解调。实验结果表明,所提出的异步贪婪算法在高信噪比下能有效逼近同步场景下的同类算法。
Large-scale Grant-Free access is one bottleneck problem in massive internet of things.Technically,active user detection and corresponding data recovery are required.At present,most schemes assume that access users are time slot synchronous.This paper considers the asynchronous Grant-Free random access..due to the lack of a stringent Uplink(UL)timing control process,the signals received by the Base Station(BS)from different active users are asynchronous,but the time deviation is controlled within a certain range.In the asynchronous Grant-Free random access scenario,this paper proposes a low complexity of greedy algorithm.This algorithm first estimates the strongest active user and its corresponding time delay,then carries on the channel estimation and signal demodulation,and then eliminates the estimated strongest active user’s contribution in the original signal.Finally the algorithm steps into the next active user detection and signal demodulation.Experimental results show that the performance of the proposed asynchronous greedy algorithm can effectively approximate the similar algorithm in synchronous scenarios with high Signal to Noise Ratio(SNR).
作者
张仁祥
宋越
李春香
吴晓富
ZHANG Renxiang;SONG Yue;LI Chunxiang;WU Xiaofu(College of Telecommunication&Information Engineering,Nanjing University of Posts and Telecommunications,Nanjing 210003,China;Unit 95958,PLA,Shanghai 200120,China)
出处
《无线电通信技术》
2022年第6期1080-1085,共6页
Radio Communications Technology
基金
国家自然科学基金(61701252)。
关键词
异步无授权随机接入
非正交多址接入
活跃用户检测
信号恢复
asynchronous grant-free random access
non-orthogonal multiple access
active user detection
date recovery
