Thanks to channel reciprocity,the time-division duplexing operation is typically used for distributed large-scale multiple-input multiple-output systems.With the knowledge of uplink channel state,APs(Access Points)per...Thanks to channel reciprocity,the time-division duplexing operation is typically used for distributed large-scale multiple-input multiple-output systems.With the knowledge of uplink channel state,APs(Access Points)perform the downlink precoding to cooperatively communicate with multiple UEs(User Equipments).Unfortunately,the channel reciprocity is often jeopardized by the non-symmetric transceiver RF(Radio Frequency)circuits at both sides of the link.By excluding UEs from the calibration procedure,the TLS(Total Least Squares)method is extended to the case of partial calibration,where only the APs are involved to exchange calibration signals to compensate for RF mismatches.Nevertheless,channel fluctuations between APs significantly degrade system performance.Therefore,we propose a scheme to obtain the diversity gain,by performing a calibration with the combination of the calibration signals of different channel coherent times.Simulation results confirm the effective performance and robustness of our scheme.展开更多
基金supported in part by the National Basic Research Program of China("973"Program)(No.2013CB336600)the Natural Science Foundation of China(NSFC)(Nos.61271205,61501113,61521061,61372100)+3 种基金National High Technol-ogy Research and Development Program of China("863"Program)(No.2014AA01A704)the Natural Science Foundation of Jiangsu Province(No.BK20150630)the Hong Kong,Macao and Taiwan Science&Technology Cooperation Program of China(No.2014DFT10290)and the Fundamental Research Funds for the Central Universities and Colleges and Universities in Jiangsu Province Plans to Graduate Research and Innovation(No.KYLX150075).
文摘Thanks to channel reciprocity,the time-division duplexing operation is typically used for distributed large-scale multiple-input multiple-output systems.With the knowledge of uplink channel state,APs(Access Points)perform the downlink precoding to cooperatively communicate with multiple UEs(User Equipments).Unfortunately,the channel reciprocity is often jeopardized by the non-symmetric transceiver RF(Radio Frequency)circuits at both sides of the link.By excluding UEs from the calibration procedure,the TLS(Total Least Squares)method is extended to the case of partial calibration,where only the APs are involved to exchange calibration signals to compensate for RF mismatches.Nevertheless,channel fluctuations between APs significantly degrade system performance.Therefore,we propose a scheme to obtain the diversity gain,by performing a calibration with the combination of the calibration signals of different channel coherent times.Simulation results confirm the effective performance and robustness of our scheme.
