不完全信道状态信息下Turbo-BLAST系统的自适应发送功率分配算法

提出了一种不完全信道状态信息下适用于Turbo-BLAST系统的自适应发送功率分配算法．所提算法以误比特率为优化目标,适用于MQAM和MPSK等不同调制方式．发送端在总功率约束条件下,利用所提的自适应发送功率分配算法对发送信号进行功率加载,以获得最小化的误比特率性能．在接收端,利用考虑信道估计误差的软干扰抵消迭代检测算法进行检测,进一步改善误比特率性能．仿真结果表明,在不完全信道状态信息条件下,采用所提算法可以有效地改善Turbo-BLAST系统的误比特率性能．     

自适应调制技术及其性能分析

介绍自适应调制技术的原理、帧格式的设计,给出调制方式的选取与转换准则;通过数值积分和仿真的方法分析了自适应调制系统在平坦瑞利衰落信道下的性能,并与固定调制方式系统进行了比较。仿真结果表明,自适应调制系统能够获得较高的系统容量,而系统的误比特率也可以保持在较低的水平。     

可见光通信中有照明限制的广义空间调制算法

可见光通信中的照明需要考虑光功率变换以及照明均匀性。为此,利用多天线脉冲幅度调制(PAM)信号空间域和幅度的特点,提出一种多天线激活的广义空间调制算法。根据不同光功率自适应改变PAM信号形式以及激活天线数。同时,利用一致界技术推导出任意光功率下该算法的误比特率上界。仿真结果表明,该算法可以在不改变传统照明性能的前提下,有效提升系统的误比特性能,且其理论模型在高信噪比条件下可以很好地预测系统的误码率。     

一种吞吐量最大化的电力线OFDM分子带自适应算法

针对低压电力线信道的实时特性及采用固定门限自适应算法时存在功率裕量的问题,提出一种基于子带动态划分的吞吐量最大化比特和功率分配算法.算法根据信道的实时状态,动态地划分子带,自适应地选择各子载波的调制模式,并在保证传输质量的前提下,合理分配功率裕量.仿真结果表明,算法能有效提高系统吞吐量,降低系统复杂度,增强电力线系统的性能.     

OFDM系统中用于快时变信道的改进型RLS信道预测

在OFDM系统中,信道的时变性限制了各种自适应技术,如自适应调制和自适应功率控制技术的实用性。提出了一种OFDM系统中用于快时变信道的改进自适应RLS预测方法。这种预测方法在不增加复杂度的条件下,比原有的方法有更好的性能。     

单用户OFDM系统中自适应调制和功率分配算法

针对现有最优算法计算复杂度高、不利于实时应用的不足,结合相关自适应比特和功率分配算法的优点,提出了一种新的单用户OFDM系统中联合自适应调制和功率分配算法,在满足给定的总发射功率门限和误码率性能的条件下使系统频谱效率最优。基于分配每比特的功率代价最小原则,找到最优子载波,自适应地将该子载波的调制方式调高一级,高效地进行比特和功率分配。仿真结果表明,新算法的频谱效率性能与最优算法相当,而平均算法复杂度却降低了接近90%,能满足实时性要求较高的业务需求。     

一种基于虚拟文件系统的集群监控方法

提出了一种自适应调制垂直-贝尔实验室分层空时结构（V-BLAST）系统的低复杂度比特、功率分配算法,满足总平均功率和单根发射天线峰值功率受限条件下使比特率最大化。该算法可以达到与比特递增分配算法相同的最优分配结果,而计算量大幅度降低。仿真结果表明,在满足目标误码率条件下单天线功率限制会使比特率降低。     

网格编码调制在无线信道下的应用

网格调制编码是将编码与调制相结合,利用信号集的冗余度来获取纠错能力.它通过增加系统设备复杂度解决了在不增加信道带宽、不降低有效信息传输速率的情况下获得明显的编码增益的问题,同时使系统的频带和功率利用率达到最佳.在无线信道下,对网格编码调制技术进行了研究,提出了基于无线信道的非对称调制信号集设计方案以及信号映射规则,进行了仿真.结果表明:在对称调制信号上,调制方式分别为4PSK和8PSK模式,编码器状态数增加相对于未编码时的BPSK和QPSK编码增益可以得到提高;非对称调制信号集相对于对称调制信号集可进一步改善编码增益.因此,网格编码技术可以在功率和频率受限的通信系统中得广泛的应用.     

运用simulink实现正交幅度调制与解调

正交幅度调制技术是一种功率和带宽相对高效的信道调制技术，因此在自适应信道调制技术中得到了较多应用。本文利用MATLAB6．5／SIMULINK4，0对调制解调系统进行仿真。首先，完成了对调幅系统（AM）的调制与解调，仿真实现了信息无失真的传输。其次，用正交幅度调制（QAM）方法实现了同时传输两路互不干扰的信号，并给出了各种仿真方法的原理。最后，为实际应用和科学合理地设计正交幅度调制系统提出了切实可行的改进建议。     

功率受限和自动重传请求条件下系统吞吐量最大化的研究

本文研究了具有ARQ功能的基于衰落信道和数据链路层缓冲区队列状态的资源最优分配问题，目标是通过自适应调整功率分配和调制方式，在系统平均功率的限制下，使系统的吞吐量达到最大。在这个系统中并不限制ARQ的重发次数，所以最大化系统的吞吐量等效于使链路层的缓冲区溢出的数据包最小。本文把这样一个优化问题构造为马尔可夫决策过程，并提出了用动态规划解决该问题的方法。出于实用性的考虑，本文还提出了一种简单的次优资源分配方法，仿真结果显示这种方法与最优的调度方法性能非常接近。     

An efficient power control scheme and joint adaptive modulation for wireless sensor networks

This paper considers wireless sensor networks (WSNs) and quantitatively rates energy efficiency obtained by combining adaptive power/rate control with adaptive modulation scheduling. For multi-access wireless sensor networks, adaptive modulation and power control are two important means to increase spectral efficiency. An adaptive modulation with power control scheme (AM with PC) which mainly reduces power consumption to achieve energy efficiency for wireless sensor networks is proposed in this paper. Cluster head node of each link adaptively adjusts its power control level and modulation type according to the signal to noise ratio (SNR) and target bit error rate (BER). The efficiency of this approach is further illustrated via numerical comparison with the original AM with PC. Simulation results demonstrate that the proposed scheme, which alleviates to save much transmission power and maintains the target bit error rate, can significantly improve the system performance.     

一种基于V-BLAST系统的跨层设计

提出了一种基于V-BLAST系统的跨层设计方案,综合考虑物理层的自适应调制和链路层的截短ARQ技术,推导了平坦衰落信道下的频谱效率和中断率。数据仿真结果表明,这种联合设计可以降低V-BLAST系统的中断率,并且获得可观的频谱效率增益。     

计算机网络在电力负荷监控系统中的应用

电力负荷监控实现的是电力管理部门对电力用户的用电情况的远地监控，它包括实现两方面的功能。一是收集分散于不同地理位置的电力用户的用电数据，并集中对这些数据进行处理；二是发送电力管理部门对各电力用户的指令及各种用电指标，基于此目的，本文介绍了电力负荷监控网络系统ＥＬＳＯ的组成，实现功能及其广泛的应用前景和意义，同时也讨论了电子邮件，ＥＴＡＭ等在负荷监控中的应用。     

基于ELM优化PI+重复控制策略在APF中的应用研究

针对传统有源电力滤波器(APF)难以适应非线性负载高电压大功率电网环境且PI参数调整缓慢的问题,基于模块化多电平换流器(MMC)的APF结构,提出一种采用极限学习机(ELM)优化电流内环PI+重复控制策略。构建基于5电平MMC拓扑结构的APF仿真模型及实验平台。仿真研究结果表明,优化后的控制策略所得负载电流THD较传统PI控制减少4.99个百分点,较PI+重复控制减少3.12个百分点。实验结果表明,补偿后的电流谐波含量较补偿前降低22.77个百分点,优化后的控制策略大大提高了系统的响应速度及补偿精度。     

单总线传感器AM2302温湿度测控系统原理及应用

新型单总线数字温湿度传感器AM2302具有体积小、功耗低、响应速度快、超长的信号传输距离等特点。本文简要介绍了单总线概念，阐述了AM2302的基本原理和控制使用方法，以及其在温湿度测控系统中的应用。经测试证明，AM2302具有安装简单、维护方便、稳定性高等优势。     

Wavelet-based envelope features with automatic EOG artifact removal: Application to single-trial EEG data

In this study, we propose an analysis system for single-trial classification of electroencephalogram (EEG) data. Combined with automatic EOG artifact removal and wavelet-based amplitude modulation (AM) features, the support vector machine (SVM) classifier is applied to the classification of left finger lifting and resting. Automatic EOG artifact removal is proposed to eliminate the EOG artifacts automatically by means of independent component analysis (ICA) and correlation coefficient. The features are then extracted from the discrete wavelet transform (DWT) data by the AM method. Finally, the SVM is used for the discriminant of wavelet-based AM features. Compared with EEG data without EOG artifact removal, band power features and LDA classifier, the proposed system achieves promising results in classification accuracy.     

Increasing deposition height stability in robotic GTA additive manufacturing based on arc voltage sensing and control

Robotic gas tungsten arc (GTA)-based additive manufacturing (AM) is a promising technique to produce high-quality and large-scale metal parts with low cost. Despite this fact, the key issue of ensuring deposition height stability has not been fully solved. In this study, an arc voltage sensing and control approach with little delay is proposed to increase the forming height stability in GTA-based AM. The deposition height stability is indirectly characterized by arc voltage signals sampled using a designed arc voltage detection system. A novel de-noising method, combining the anti-impulse interference moving average with the wavelet packet transform, is proposed to filter out interferences in the original arc voltage. A Fuzzy-PID controller is developed to control the arc voltage by adjusting the wire feed speed on next deposition layer. Constant parameter and closed-loop control experiments are compared via fabricating thin-walled parts. The more stable arc voltage and more excellent forming appearance in the closed-loop control test indicate that applying the arc voltage sensing and control system can greatly improve the forming height stability in robotic GTA-based AM.     

Hybrid Renewable Energy Source Combined Dynamic Voltage Restorer for Power Quality Improvement

In this paper, the hybrid photovoltaic-thermoelectric generator (PV-TEG) combined dynamic voltage restorer (DVR) system is proposed for the power quality disturbances compensation in a single-phase distribution system. The stable and precise level of input voltage is essential for the smooth and trouble-free operation of the electrically sensitive loads which are connected at the utility side to avoid system malfunctions. In this context, the hybrid PV-TEG energy module combined DVR system is proposed in this paper. With the support of the hybrid energy module, the DVR will perform the power quality disturbances compensation effectively with needed voltage and /or power. In the proposed system, the PV and TEG energy sources are connected electrically in series to produce adequate voltage for the DVR operation and the fractional factor-based variable incremental conduction (FFVINC) maximum power point tracking (MPPT) control algorithm is employed to extract the possible maximum power from the PV array. The intelligent fuzzy logic controller (FLC) is chosen for implementing the MPPT control algorithm. The half-bridge voltage source inverter (VSI) circuit and in-phase voltage compensation technique are used in the DVR for better power quality disturbances compensation. The performance and usefulness of the proposed DVR system are investigated by an extensive simulation study with four different modes of operation, the study results are confirmed that the proposed system promptly identifies the power quality disturbances for compensation. Moreover, the investigation proved that the combined PV and TEG energy module can provide better energy efficiency in converting solar irradiation into electricity.     

基于专家系统的采煤机截割电动机恒功率控制

为了很好地适应煤岩特性的变化、有效发挥采煤机截割电动机的能力,解决采煤机截割电动机运行时功率波动较大的问题,利用专家系统的理论和方法,建立了基于专家系统的采煤机截割电动机恒功率控制系统,该系统通过对牵引速度实时调节,使采煤机的截割电动机恒功率运行。利用MATLAB/simulink构建了该系统的仿真模型,仿真试验表明,该系统对牵引速度具有超前预见性,比一般控制系统的调节时间缩短0.62s,截割电动机的功率超调减小3.8%,反应灵敏、波动小、工作平稳。     

一种低纹波的推挽变换器控制算法研究

提出一种基于双闭环控制和重复控制的推挽变换器设计方法.针对车载蓄电池的输出电流纹波精度要求,通过理论分析对推挽变换器进行建模,并优化设计了推挽变换器平均电压外环电流内环的双闭环控制器参数;同时根据车载逆变器的应用环境,采用一种重复控制策略有效抑制电压误差中的交流分量,简化了控制器的设计.通过实际试验数据,验证了所设计的控制器的可行性和优越性.