Media based modulation(MBM)is expected to be a prominent modulation scheme,which has access to the high data rate by using radio frequency(RF)mirrors and fewer transmit antennas.Associated with multiuser multiple inpu...Media based modulation(MBM)is expected to be a prominent modulation scheme,which has access to the high data rate by using radio frequency(RF)mirrors and fewer transmit antennas.Associated with multiuser multiple input multiple output(MIMO),the MBM scheme achieves better performance than other conventional multiuser MIMO schemes.In this paper,the massive MIMO uplink is considered and a conjunctive MBM transmission scheme for each user is employed.This conjunctive MBM transmission scheme gathers aggregate MBM signals in multiple continuous time slots,which exploits the structured sparsity of these aggregate MBM signals.Under this kind of scenario,a multiuser detector with low complexity based on the compressive sensing(CS)theory to gain better detection performance is proposed.This detector is developed from the greedy sparse recovery technique compressive sampling matching pursuit(CoSaMP)and exploits not only the inherently distributed sparsity of MBM signals but also the structured sparsity of multiple aggregate MBM signals.By exploiting these sparsity,the proposed CoSaMP based multiuser detector achieves reliable detection with low complexity.Simulation results demonstrate that the proposed CoSaMP based multiuser detector achieves better detection performance compared with the conventional methods.展开更多
利用相同器件工艺在两种不同材料结构上制备了Al N/Ga N高电子迁移率晶体管(HEMT),研究了Al Ga N背势垒结构对器件特性的影响。测试结果表明,有背势垒结构的器件最大饱和电流密度和峰值跨导要小于无背势垒结构器件,栅压偏置为+1 V时,无...利用相同器件工艺在两种不同材料结构上制备了Al N/Ga N高电子迁移率晶体管(HEMT),研究了Al Ga N背势垒结构对器件特性的影响。测试结果表明,有背势垒结构的器件最大饱和电流密度和峰值跨导要小于无背势垒结构器件,栅压偏置为+1 V时,无背势垒的Al N/Ga N HEMT器件最大饱和电流密度为1.02 A·mm-1,峰值跨导为304 m S·mm-1,有背势垒结构的器件饱和电流密度为0.75 A·mm-1,峰值跨导为252 m S·mm-1。有背势垒结构器件的亚阈值斜率为136 m V/dec,击穿电压为78 V;无背势垒结构器件的亚阈值斜率为150 m V/dec,击穿电压为64 V。栅长为0.25μm有背势垒结构的器件电流截止频率高于无背势垒结构器件,最高振荡频率要低于无背势垒结构的器件。展开更多
文摘传统的全球导航卫星系统(GNSS)信号模拟器通道群时延标定方法有相位翻转点法和相关峰法两种,两者均在零伪距或固定伪距的特殊仿真场景下进行测量,且在通道传输特性非理想的情况下测得的群时延均存在偏差.提出了基于闭环伪距测量的模拟器通道群时延标定方法,并设计实现了GNSS信号模拟器通道群时延标定系统.首先,采用高速直接射频采样存储系统对模拟器正常星座动态仿真场景下输出的导航信号和秒脉冲(1 PPS)信号同时进行记录.其次,使用软件接收机对信号进行捕获跟踪,利用三次样条插值判定1 PPS上升沿位置作为伪距观测历元时刻,对软件接收机的伪距观测量和模拟器仿真的伪距记录值做数据比对,得到模拟器的群时延标定值.最后,分别利用上述方法对两种商用模拟器的群时延进行了标定,实验结果表明,闭环伪距测量法有效可行,测量不确定度优于0.7 ns.
文摘Media based modulation(MBM)is expected to be a prominent modulation scheme,which has access to the high data rate by using radio frequency(RF)mirrors and fewer transmit antennas.Associated with multiuser multiple input multiple output(MIMO),the MBM scheme achieves better performance than other conventional multiuser MIMO schemes.In this paper,the massive MIMO uplink is considered and a conjunctive MBM transmission scheme for each user is employed.This conjunctive MBM transmission scheme gathers aggregate MBM signals in multiple continuous time slots,which exploits the structured sparsity of these aggregate MBM signals.Under this kind of scenario,a multiuser detector with low complexity based on the compressive sensing(CS)theory to gain better detection performance is proposed.This detector is developed from the greedy sparse recovery technique compressive sampling matching pursuit(CoSaMP)and exploits not only the inherently distributed sparsity of MBM signals but also the structured sparsity of multiple aggregate MBM signals.By exploiting these sparsity,the proposed CoSaMP based multiuser detector achieves reliable detection with low complexity.Simulation results demonstrate that the proposed CoSaMP based multiuser detector achieves better detection performance compared with the conventional methods.
文摘利用相同器件工艺在两种不同材料结构上制备了Al N/Ga N高电子迁移率晶体管(HEMT),研究了Al Ga N背势垒结构对器件特性的影响。测试结果表明,有背势垒结构的器件最大饱和电流密度和峰值跨导要小于无背势垒结构器件,栅压偏置为+1 V时,无背势垒的Al N/Ga N HEMT器件最大饱和电流密度为1.02 A·mm-1,峰值跨导为304 m S·mm-1,有背势垒结构的器件饱和电流密度为0.75 A·mm-1,峰值跨导为252 m S·mm-1。有背势垒结构器件的亚阈值斜率为136 m V/dec,击穿电压为78 V;无背势垒结构器件的亚阈值斜率为150 m V/dec,击穿电压为64 V。栅长为0.25μm有背势垒结构的器件电流截止频率高于无背势垒结构器件,最高振荡频率要低于无背势垒结构的器件。
