Utilizing channel reciprocity, time reversal（TR） technique increases the signal-to-noise ratio（SNR） at the receiver with very low transmitter complexity in complex multipath environment. Present research works abo...Utilizing channel reciprocity, time reversal（TR） technique increases the signal-to-noise ratio（SNR） at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output（MIMO） communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems.展开更多
For the issue of deterioration in detection performance caused by dynamically changing environment in ultra-wideband（UWB） multiple input multiple output（MIMO） radar, this paper proposes a novel adaptive waveform d...For the issue of deterioration in detection performance caused by dynamically changing environment in ultra-wideband（UWB） multiple input multiple output（MIMO） radar, this paper proposes a novel adaptive waveform design which is aimed to improve the ability of discriminating target and clutter from the radar scene. Firstly, a sequence of Morlet wavelet pulses with frequency hopping and pulse position modulation by Welch-Costas array is designed. Then a waveform optimization solution is proposed which is achieved by applying the minimization mutual-information（MI） strategy. After that, with subsequent iterations of the algorithm, simulation results demonstrate that the optimal waveform design method brings an improvement in the target detection ability in the presence of noise and clutter.展开更多
针对5G车对车(vehicle to vehicle,V2V)无线通信系统,基于几何随机建模方法,提出一种改进的三维宽带多输入多输出(multiple-input and multiple-outpit,MIMO)信道模型。引入多共焦半椭球体模型用于研究不同传播延迟下的V2V信道统计特性...针对5G车对车(vehicle to vehicle,V2V)无线通信系统,基于几何随机建模方法,提出一种改进的三维宽带多输入多输出(multiple-input and multiple-outpit,MIMO)信道模型。引入多共焦半椭球体模型用于研究不同传播延迟下的V2V信道统计特性,结合时变的路径长度、信号角度和莱斯因子表征V2V信道的非平稳特性。推导了空-时相关函数、多普勒功率谱密度等关键信道统计特性的数学表达式。分析了城市和高速场景下信道相关特性的差别,并研究了车流密度、运动方向、天线角度、传播延迟等因素对信道统计特性的影响。结果表明,城市场景下的时间相关性和空间相关性明显低于高速场景;不同传播延迟下的V2V信道统计特性有明显差异;信道相关性同天线阵列角度、收发车运动方向和时间变化密切相关。模型仿真结果为车载通信提供了一些有价值的结论,可以作为未来V2V通信系统设计、优化和评估的有效指导。仿真结果与实测数据较好地吻合,证明模型能正确表征V2V无线信道的相关特性。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61331007,61361166008,and 61401065)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120185130001)
文摘Utilizing channel reciprocity, time reversal（TR） technique increases the signal-to-noise ratio（SNR） at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output（MIMO） communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems.
基金supported by the National Natural Science Foundation of China(6107114561271331)
文摘For the issue of deterioration in detection performance caused by dynamically changing environment in ultra-wideband（UWB） multiple input multiple output（MIMO） radar, this paper proposes a novel adaptive waveform design which is aimed to improve the ability of discriminating target and clutter from the radar scene. Firstly, a sequence of Morlet wavelet pulses with frequency hopping and pulse position modulation by Welch-Costas array is designed. Then a waveform optimization solution is proposed which is achieved by applying the minimization mutual-information（MI） strategy. After that, with subsequent iterations of the algorithm, simulation results demonstrate that the optimal waveform design method brings an improvement in the target detection ability in the presence of noise and clutter.
文摘针对5G车对车(vehicle to vehicle,V2V)无线通信系统,基于几何随机建模方法,提出一种改进的三维宽带多输入多输出(multiple-input and multiple-outpit,MIMO)信道模型。引入多共焦半椭球体模型用于研究不同传播延迟下的V2V信道统计特性,结合时变的路径长度、信号角度和莱斯因子表征V2V信道的非平稳特性。推导了空-时相关函数、多普勒功率谱密度等关键信道统计特性的数学表达式。分析了城市和高速场景下信道相关特性的差别,并研究了车流密度、运动方向、天线角度、传播延迟等因素对信道统计特性的影响。结果表明,城市场景下的时间相关性和空间相关性明显低于高速场景;不同传播延迟下的V2V信道统计特性有明显差异;信道相关性同天线阵列角度、收发车运动方向和时间变化密切相关。模型仿真结果为车载通信提供了一些有价值的结论,可以作为未来V2V通信系统设计、优化和评估的有效指导。仿真结果与实测数据较好地吻合,证明模型能正确表征V2V无线信道的相关特性。
