共查询到17条相似文献,搜索用时 62 毫秒
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可见光通信(VLC)系统通常采用多阵列光源布局方式来兼顾照明与通信双重功能,因此需要使用多输入多输出(MIMO)技术进行多天线协同传输来实现高速率通信。然而传统MIMO系统中采用平均功率分配来实现空间复用,无法充分体现MIMO多天线协调传输的优势。根据每组收发天线信道状态的差异,设计了一种低计算复杂度的快速迭代注水算法,可实现依据信道特征自适应的分配信息,从而提高系统的信道容量。仿真结果表明:在相同信噪比情况下注水算法自适应功率分配系统比等功率分配系统的信道容量提高了1.25 bit/Hz左右。 相似文献
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针对空分复用的紫外光通信网络中链路间多用户干扰的问题.基于一组典型的通信链路模型,采用紫外光多次散射理论,应用蒙特卡洛方法对系统的误码率与通信节点间距离、链路间夹角、收发仰角等参量间的关系进行分析.结果表明:误码率随着通信节点间距离的增大而增大,发射功率为100mW时,通信距离应小于120m;随着链路间夹角的增大,误码率先减小后逐渐保持不变,然后又增大,链路间夹角在60°~120°内取值;接收端仰角和发射端仰角对误码率的影响几乎相同,即随着收发仰角的增大,误码率先减小后迅速增大,15°时误码率最小. 相似文献
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基于摄像头的多光源多输入多输出(MIMO)通信系统能够提高光源的利用率和传输带宽,但多光源之间的干扰和环境光的干扰为可见光的颜色判断带来了极大的困难。针对这种情况,提出了基于自联想神经网络的可见光MIMO颜色检测算法。设计了基于自联想神经网络的主成分提取方法,在训练速度和模型准确率方面取得平衡;提出了神经网络学习光源颜色的具体训练方法,基于欧氏距离决定光源的实际颜色符号。在真实的实验数据集的基础上完成了验证实验,结果显示该算法实现了较好的收敛速度和较高的检测准确率。 相似文献
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大气湍流对无线光通信系统的影响不可忽视,为了更准确地反映实验室模拟多输入、多输出(MIMO)大气湍流信道的实际特征,提出了一种利用相位屏来模拟MIMO大气湍流信道的方法,并针对基于液晶空间光调制器(LC-SLM)的液晶调制法展开研究,通过实验验证该方法的可行性。实验结果表明:通过相位屏模拟MIMO大气湍流信道的激光光斑发生不同程度的畸变,湍流环境下两路激光发射系统比单路发射激光系统功率稳定性好,在前向纠错误差极限(3.8×10-3)下,单个发射单个接收系统的链路代价为10.5 dB,2个发射2个接收的MIMO系统的链路代价为9.3 dB。该项研究对于实验室模拟MIMO大气湍流信道实验方法提供一种新思路。 相似文献
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针对起伏地形环境下紫外光非直视通信路径损耗大、站点选址难的问题,提出了基于数字高程模型(DEM)的紫外光非直视传输的最佳收、发仰角求解方法。依托紫外光非直视单次散射模型,研究了路径损耗与收、发仰角之间的关系。针对不同地形原始DEM数据,通过插值提高分辨率,并提出了切线传输方案。采用顺序遍历法对收、发端位置及仰角变化对通信系统路径损耗的影响进行了研究。仿真结果表明,路径损耗在[10°,80°]收、发仰角区间内为增函数。在使用反距离加权插值法提高数据分辨率后,路径损耗值相较原始数据分别降低了0.014 dB、0.043 dB和0.385 dB。当按切线传输方案布设时,通信系统路径损耗值最小,设计的仿真程序可为收、发端站点科学布设提供支持。 相似文献
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无线紫外光局域通信是在短距离内实现全方位信息安全传输的有效途径之一,其中数据传输速率是该类通信系统的重要技术指标。从常用的紫外收发通信系统结构出发,研究无线紫外光局域通信数据传输速率的影响因素。研究结果表明:大气信道和紫外光源的选择对系统数据传输速率影响较大;由于大气散射信道的多径时延,系统的最大调制速率受到限制,当通信距离较短或天气环境较好时,系统的最大调制速率较高;紫外光源中,低压汞灯最大调制速率20kHz,紫外LED最大调制速率为几兆赫兹左右。相关研究成果为高速紫外光局域网络的设计与应用提供了参考。 相似文献
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为了实现对测试性指标的合理高效分配,考虑当前测试性发展的主流技术,以及分析测试性分配影响因素的基础上,提出了基于二次线性插值的测试性分配方法;运用测试性建模的理念,首先对系统进行横向划分和纵向划分,实现LRU与功能属性之间的映射关系,并对LRU进行聚类,根据聚类结果对指标进行第一次分配,即把指标分配给功能属性;然后,在功能属性的要求下,考虑各LRU的故障率、测试和故障扩散强度等特性参数,进行第二次插值分配;最后用实例进行了验证,结果表明:分配过程简单,结果可信无需修正,更符合实际要求;提出的方法打破了传统级级分配测试性指标的理念,采用两次分配即可实现系统级指标到LRU级指标的分配。 相似文献
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Full-duplex (FD) transmission holds a great potential of improving the sum data rate of wireless communication systems. However, the self-interference introduced by the full-duplex transmitter brings a big challenge to enhance the energy efficiency. This paper investigates the power allocation problem in a full-duplex two-way (FDTW) communication network over an OFDM channel, aiming at improving the sum data rate and energy efficiency. We first characterize the sum rate and energy efficiency achieved in a single-carrier FDTW system. The optimal transmit power that achieves the maximal sum data rate is presented. The energy efficiency maximization problem is solved by using fractional programming. Then we further formulate sum rate and energy efficiency maximization problem in a multi-subcarrier FDTW system. In particular, the sub-optimal transmit power allocation which achieves a decent sum rate improvement is found by using a proposed iterative algorithm. By combining the iterative algorithm and fractional programming, we further maximize the energy efficiency of the multi-subcarrier system. With our proposed algorithm, we can easily obtain an optimal transmit power that approximates the global optimal solution. Simulation results show that using the obtained optimal transmit power allocation algorithm can significantly improve the sum rate and energy efficiency in both single-carrier and multi-subcarrier systems. 相似文献
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We study the influence of the discreteness of information about the channel state, which is transmitted over the receiver–transmitter return line, on the effeiciency of MIMO systems. It is shown that such a discreteness results in energy losses and appearance of crosstalk in parallel eigenchannels of the MIMO system. We propose a method of crosstalk suppression, which ensures a pronounced decrease in the energy losses and restores the nondependence of eigenchannels with respect to transmitted symbols but leads to the correlation of output internal noise. Expressions for a maximum likely estimate of received signals are derived with allowance for the noise correlation. Mathematical simulation results showing the high efficiency of the proposed method are presented for the case of Rayleigh fading of signals. 相似文献
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非视线紫外通信大气传输特性的蒙特卡罗模拟 总被引:3,自引:4,他引:3
基于蒙特卡罗方法建立了紫外光非视线传输多次散射模型,利用单次散射近似法和实验方法验证了模型的有效性,并利用该模型完成了非视线紫外光通信大气传输特性的模拟.模拟时光波长取紫外光通信的最佳工作波段(250 nm附近),分析了不同传输距离下能见度、风、雨、雾等参量对系统能量透射比的影响.结果指出,系统能量透射比随传输距离增大而剧烈减小,在天气较差传输条件下能量衰减得更快;风力大小的变化对通信系统影响不大.较近距离通信传输时(一两百米),通信系统受天气条件的影响较小. 相似文献
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Ning Luan Ke Xiong Zhifei Zhang Haina Zheng Yu Zhang Pingyi Fan Gang Qu 《Entropy (Basel, Switzerland)》2021,23(9)
This article investigates a relay-assisted wireless powered communication network (WPCN), where the access point (AP) inspires the auxiliary nodes to participate together in charging the sensor, and then the sensor uses its harvested energy to send status update packets to the AP. An incentive mechanism is designed to overcome the selfishness of the auxiliary node. In order to further improve the system performance, we establish a Stackelberg game to model the efficient cooperation between the AP–sensor pair and auxiliary node. Specifically, we formulate two utility functions for the AP–sensor pair and the auxiliary node, and then formulate two maximization problems respectively. As the former problem is non-convex, we transform it into a convex problem by introducing an extra slack variable, and then by using the Lagrangian method, we obtain the optimal solution with closed-form expressions. Numerical experiments show that the larger the transmit power of the AP, the smaller the age of information (AoI) of the AP–sensor pair and the less the influence of the location of the auxiliary node on AoI. In addition, when the distance between the AP and the sensor node exceeds a certain threshold, employing the relay can achieve better AoI performance than non-relaying systems. 相似文献