基于散射中心模型的目标时域回波快速仿真

为快速获取超宽带电磁脉冲激励下雷达目标在时域上的电磁响应,提出一种基于属性散射中心正向建模的方法用于目标时域回波仿真。从目标几何模型出发,利用射线追踪、分集技术对空间中所有射线进行标记与归类,分离并定量表征目标的强散射源。基于属性散射中心模型,正向确定模型参数,构建出目标属性散射中心模型,在选定的辐射源激励下进行仿真计算,快速获取目标时域回波信号。以典型目标简化坦克为例,选取不同形式的超宽带电磁脉冲信号作为辐射源,基于正向建模方法构建简化坦克的散射中心模型,快速获取给定电磁脉冲激励下的雷达回波信号,并与利用高频仿真方法得到的一维距离像对比,结果具有较好的一致性,从而验证了利用散射中心模型快速进行不同辐射源激励下回波仿真的有效性。     

Performance analysis of time-hopping m-ary UWB wireless system using V-BLAST algorithm

Ultra WideBand (UWB) transmissions are attractive for low power, baseband asynchronous multiple access and peer-to-peer wireless communications. Multiple Input Multiple Output (MIMO) technology is useful in combating against multipath and at the same time improves system performance by using multielement antennas at both transmitter and receiver. This letter proposes a time hopping M-ary UWB systems using V-BLAST algorithm, and power control is considered for better performance. Simulations are provided to compare performance with different antennas.     

基于折叠枝节加载多模谐振器的超宽带滤波器

针对超宽带滤波器的插入损耗和选择性问题,提出一种基于折叠枝节加载多模谐振器结构的超宽带滤波器。通过调节谐振器的阻抗比及电长度比,可以控制谐振频率。仿真与实验结果吻合良好,表明采用折叠枝节加载形式,可以使滤波器具有低插入损耗和良好的选择性。通带范围在2.9~10.7 GHz,带内插入损耗优于1 d B,实现相对带宽114%。     

基于双本振同步Nyguist折叠接收机的多分量LFM信号检测及参数估计

Nyquist折叠接收机(NYFR)为一种新颖的超宽带接收机结构,它可以利用单片ADC实现超宽带范围内信号的采集,而同步Nyquist折叠接收机(SNYFR)为其一种改进结构。该文在此基础上提出一种新的基于双本振方案的SNYFR结构,推导了多分量LFM输入下的数学模型。并基于此结构,提出一种基于正弦调频匹配(SFMM)与分数阶域折叠补偿相结合的多分量LFM信号奈奎斯特区域(NZ)判定与参数估计算法,克服了单本振SNYFR结构处理多分量LFM输入时的困难,提高了NZ判定及参数估计的抗噪声性能。计算机仿真表明,该文算法可以有效地对多分量LFM信号进行检测并实现各分量参数的高精度估计。     

Wireless inter-chip interconnects

Inter-chip wireless interconnect technologies such as inductive coupling and electromagnetic wave propagation have been developed for future high performance system in package at low cost. Inductive coupling is used for near field transmission whose distance is shorter than 100 μm as local wireless interconnects. Antennas are used for far field transmission between chips whose distance is longer than 1 cm as global wireless interconnects. A single-chip Gaussian monocycle pulse (GMP) transmitter using complementary metal oxide semiconductor (CMOS) technology with an on-chip integrated antenna was developed for inter-chip ultra wideband (UWB) communication.     

Application of power transformation and moments in time based UWB ranging

For ultra-wideband (UWB) ranging, TOA estimation with the energy detection (ED) receiver is to detect the energy sample that contains the first path (FP) signal in dense multipath. Threshold crossing (TC) is used frequently. However, it is difficult to determine the threshold. Some threshold setting methods are based on constant false alarm rate (CFAR) and the chi-squared distribution. However, the distribution is complicated. Moreover, it depends on the degree of freedom (DOF). If the DOF used is wrong, it will degrade the detection performance. The study bypasses the distribution. We first examine the distribution of the output of the ED receiver after power transformation. Based on the new characteristics of the transformed data and approximate distributions, we propose some practical TOA estimation methods. Similarly, the moments of the output of the ED receiver, such as the second or one-third order moments, are also analysed and used. The proposed methods are easy to implement and can achieve about the same ranging performance with methods based on the chi-squared distribution. We provide both theoretical and simulation results to prove their effectiveness.     

一种用于五频带的MB-OFDM超宽带的6至9GHz的CMOS频率综合器

本论文设计了一个超宽带频率综合器。该频率综合器通过采用两个锁相环和一个单边带混频器产生了6至9GHz内的五个频带中心频率,频带之间的跳频时间小于3纳秒。文中提出了一个高线性度的二选一多路选择器,一个宽带的单边带混频器和一个正交压控振荡器。此外,版图也做了一些特殊考虑。该频率综合器采用0.18微米CMOS工艺实现,在1.5V至1.8V电源电压下消耗40mA电流,测试结果显示10MHz频偏处的相位噪声为-128dBc/Hz,在7.656GHz频带处的边带抑制为-22dBc。     

新的非相干UWB系统平均性能的理论计算方法

针对IEEE 802.15.3a信道下UWB非相干接收机的平均误码率计算问题,基于簇生点过程模型给出了一种新的求解方法.该方法通过推导接收窗口内信噪比的均值和方差的闭合表达式,分别以高斯分布和对数正态分布近似其概率分布,给出计算UWB能量检测系统平均误码率的闭合表达式.对比分析对数正态分布、高斯分布与真实分布之间的数字特征,对数正态分布近似效果的合理性好于高斯分布近似.对比基于OOK和PPM 2种调制方式的平均误码率指标,实验结果表明对数正态分布近似效果的有效性要好于高斯分布近似.     

认知超宽带网络的容量分析和最优化

The integration of cognitive radio and Ultra wideband (UWB) networks has attracted lots of research interests. Cognitive UWB networks not only provide very high data rates but also guarantee the uninterrupted communication of primary system operated in the same frequency band. In this work, the problem of the capacity analyses of cognitive UWB networks is investigated. Different from the conventional cognitive spectrum sharing model which can only utilize the idle spectrum hole, the cognitive UWB system can...     

2～12 GHz CMOS超宽带低噪声放大器设计

提出了一种基于双反馈电流复用结构的新型CMOS超宽带(UWB)低噪声放大器(LNA),放大器工作在2～12 GHz的超宽带频段,详细分析了输入输出匹配、增益和噪声系数的性能。设计采用TSMC 0.18μm RF CMOS工艺,在1.4 V工作电压下,放大器的直流功耗约为13mW(包括缓冲级)。仿真结果表明,在2～12 GHz频带范围内,功率增益为15.6±1.4 dB,输入、输出回波损耗分别低于-10.4和-11.5 dB,噪声系数(NF)低于3 dB(最小值为1.96 dB),三阶交调点IIP3为-12 dBm,芯片版图面积约为712μm×614μm。