无蜂窝大规模MIMO的接入点间同步与空口校准技术  

Inter-Access Point Synchronization and Over-The-Air Reciprocal Calibration for Cell-Free Massive MIMO Systems

作　　者：梁祥虎 王晓妮[2] 李原[2] 郑康[1] 王东明[1] LIANG Xianghu;WANG Xiaoni;LI Yuan;ZHENG Kang;WANG Dongming(National Mobile Communications Research Laboratory,Southeast Uni-versity,Nanjing 210096,China;ZTE Corporation,Shenzhen 518057,China)

机构地区：[1]东南大学移动通信国家重点实验室,中国南京210096 [2]中兴通讯股份有限公司,中国深圳518057

出　　处：《中兴通讯技术》2024年第3期81-90,共10页ZTE Technology Journal

基　　金：国家科技重点研发项目(2020YFB1807200);东南大学-中兴通讯联合实验室项目。

摘　　要：无线通信系统中多个天线单元相干协作发送(CJT)技术的性能严重依赖于发送端已知信道状态信息(CSI)。为了避免CSI反馈,通常假设系统工作在时分双工(TDD)模式。利用TDD空口上下行信道的互易性,根据上行探测信道获得下行CSI。但是,实际系统中由于节点(AP)间存在同步误差及通道的非理想因素,上下行整体信道并不互易。研究了面向无蜂窝大规模MIMO的网络侧时频同步以及空口(OTA)校准技术。基于现网商用远端天线单元(RRU)以及同步技术,给出了大规模组网的同步和空口校准方案。结合试验系统,探讨了CJT对同步和校准的性能的要求以及无蜂窝大规模MIMO实现方式和节点天线配置,给出了校准相位的预测性能。The performance of coherent joint transmission(CJT)techniques with multiple access points in wireless communication systems is highly dependent on known channel state information(CSI)at the transmitter.To avoid CSI feedback,it is generally assumed that systems operate in time division duplex(TDD)mode,and then the downlink CSI is obtained according to the uplink sounding signals by using the reci-procity of the uplink and downlink channels.However,due to the synchronization error between access points(AP)and the non-ideal hard-ware factors,the uplink and downlink channels are not reciprocal.In this paper,the time-frequency synchronization of the wireless network and over-the-air(OTA)calibration technologies for cell-free massive MIMO are studied.Based on the commercial remote radio unit(RRU)and synchronization technology,synchronization and calibration schemes for large-scale network are discussed.Finally,based on the ex-perimental system,the performance requirements of CJT for synchronization and calibration are discussed,as well as the implementation of cell-free massive MIMO and the antenna configuration of the AP,and the prediction of the phase of the calibration coefficient is studied.

关 键 词：无蜂窝大规模MIMO 相干协作发送 空口校准 节点间同步 

分 类 号：TN929.5[电子电信—通信与信息系统]