传统正交频分复用(orthogonal frequency division multiplexing,OFDM)帧同步方法,如基于前导序列、基于导频、基于深度学习的帧同步算法在面对Starlink高速率、高动态通信环境时局限于单路计算思路,且具有较多的资源消耗和较高的时钟...传统正交频分复用(orthogonal frequency division multiplexing,OFDM)帧同步方法,如基于前导序列、基于导频、基于深度学习的帧同步算法在面对Starlink高速率、高动态通信环境时局限于单路计算思路,且具有较多的资源消耗和较高的时钟需求。而基于差分相移键控(symmetric differential phase shift keying,SDPSK)调制的多路并行帧同步算法虽然引入频偏矫正和本地前导序列相关使得性能上有所提升并降低了时钟需求,但加大了计算量和硬件资源占用。针对以上情况,基于Starlink公开前导结构,提出了四路并行的基于频偏矫正辅助的Starlink下行信号帧同步轻量化电路设计。首先,设计基于延时相关复用的轻量化粗帧同步和频偏估计结构使电路在频偏估计时不需要再次计算延时相关值。然后,提出基于四路并行直接数字式频率合成器(direct digital synthesizer,DDS)的轻量化频偏矫正模块避免单路信号在多路结构下变频时需要缓存。最后,设计基于符号相关和查找表复数乘法器的轻量化精帧同步结构减少了本地序列和信号相关的资源耗用,在保证性能的前提下使得查找表(look-up table,LUT)、查找表随机存取存储器(look-up table random access memory,LUTRAM)、触发器(flip-flop,FF)、块随机存取存储器(block random access memory,BRAM)资源分别节省了7%、2%、5%和8%。对电路编写verilog代码进行现场可编程门阵列(field programmable gate array,FPGA)实现,并通过Xilinx生产的xczu47dr芯片上板验证了其资源占用及性能表现。展开更多
Based on the analyses on arch and peltate venation structures, the design of reinforcing frames was improved. First, distribution rules of the arch structure were summarized. According to the load condition and the st...Based on the analyses on arch and peltate venation structures, the design of reinforcing frames was improved. First, distribution rules of the arch structure were summarized. According to the load condition and the structure of the frame, a mechanical model of arch structure was devel- oped, and two solutions for the model were analyzed and compared with each other. Through the a- nalysis, application rules of arch structure for improving the design were obtained. Then, distribu- tion rules of peltate venation structure were summarized. By using the same method, application rules of peltate venation structure for improving the design were also obtained. Finally, mechanical problem of the frame was described, and rib arrangement of the frame was redesigned. A parameter optimization for the widths of ribs in bionic arrangement was also carried out to accomplish the im- proving design. Comparison between bionic and conventional reinforcing frames shows that the weight is reduced by as much as 15.3%.展开更多
基金Supported by the National Natural Science Foundation of Chi- na （ 50975012 ） Research Fund for the Doctoral Program of Higher Education of China （ 20091102110022 ） Innovation Foundation of BUAA for PhD Graduates （YWF-12-RBYJ-015）
文摘Based on the analyses on arch and peltate venation structures, the design of reinforcing frames was improved. First, distribution rules of the arch structure were summarized. According to the load condition and the structure of the frame, a mechanical model of arch structure was devel- oped, and two solutions for the model were analyzed and compared with each other. Through the a- nalysis, application rules of arch structure for improving the design were obtained. Then, distribu- tion rules of peltate venation structure were summarized. By using the same method, application rules of peltate venation structure for improving the design were also obtained. Finally, mechanical problem of the frame was described, and rib arrangement of the frame was redesigned. A parameter optimization for the widths of ribs in bionic arrangement was also carried out to accomplish the im- proving design. Comparison between bionic and conventional reinforcing frames shows that the weight is reduced by as much as 15.3%.
