TD-SCDMA集群系统中的联合功率控制

TD-SCDMA集群系统中存在各种干扰,传统的功率控制算法无法消除来自集群群组间的用户干扰。采用了先用波束赋形进行主波瓣外干扰抑制,然后进行多群组联合检测来消除波瓣内群组间干扰,再联合功率控制的两步迭代算法来进一步消除集群中的干扰,从而降低了系统对功控的要求,提高了性能。仿真结果证明,该算法能有效降低系统发射功率和抑制干扰。     

无线携能通信系统中基于人工噪声的波束成形算法研究

在存在多天线窃听者的情况下,研究了无线携能通信系统的物理层安全传输问题。传统上,人工噪声方案是一种保证物理层安全通信的有效策略。因此,提出了一种人工噪声辅助的波束成形算法,以提高信息与能量联合传输的安全性。该算法在满足多项约束（接收端能量采集门限、信息泄漏控制指标和发送功率）的基础上,通过优化波束成形预编码矩阵和人工噪声实现无线携能通信系统的物理层安全通信。在数学上该算法是一个非凸优化问题,不易求解。为此,首先引入最小均方误差接收算法和连续凸近似方法将其转换为凸的二阶锥规划子问题,然后对该凸问题进行迭代求解。仿真结果表明,该算法能够在保证窃听者无法解码信息的同时,实现信息和能量的联合传输,并且算法收敛速度快。     

认知无线电网络中接入控制和功率波束形成的联合优化

在认知无线电网络中,针对鲁棒性的多用户接入控制和发射功率波束形成的联合优化问题,提出了基于熵函数光滑近似的联合优化方案。首先,利用L₀-范数最小化将接入控制和发射功率波束两个优化问题转化为一个联合优化问题;然后,利用基于熵函数光滑近似的方法对L₀-范数的非凸性及不连续性问题加以优化;最后,由于光滑可微的目标函数为单峰函数,将问题变形为增广Lagrange函数,利用Armijo梯度下降法得到问题的最优解。数值结果分析表明：新算法在信干噪比（SINR）较低时虽然所提算法的接入量无明显提高,但是在SINR较高时所提算法能显著降低发射功率并提高次用户的接入量。模型中对不确定的信道状态信息（CSI）加以分析,可以使网络更好地适应外界的变化,提高网络的可靠性,所提算法可以有效地实现网络资源的优化配置,提高网络性能。     

Distributed power adjustment based on control theory for cognitive radio networks

In this paper, we propose two power adjustment methods for cognitive radio networks. In the first algorithm, the transmitter derives the transmission power with PID control in order to satisfy the QoS constraints in secondary networks. The derived transmission power is compared with a constraint condition in order to avoid the interference with primary networks, and then the actual transmission power is decided. Because the constraint condition affects the performance of our proposed method significantly, we propose an effective update algorithm. On the other hand, the second algorithm is based on model predictive control (MPC). In this method, the decision of transmission power is formulated as quadratic programming (QP) problem and the transmission power is derived directly with the constraint condition. We evaluate the performances of our proposed methods with simulation and compare the proposed methods with the distributed power control (DPC) method. In numerical examples, we show that our proposed methods are more effective than the existing method in some situations. We also prove analytically that the interference with primary networks can be avoided with probability one by using our proposed method if each transmitter has the information about every channel gain.     

An advanced FMRL controller for FACTS devices to enhance dynamic performance of power systems

The parameters of power system slowly change with time due to environmental effects or may change rapidly due to faults. It is preferable that the control technique in this system possesses robustness for various fault conditions and disturbances. The used flexible alternating current transmission system (FACTS) in this paper is an advanced super-conducting magnetic energy storage (ASMES). Many control techniques that use ASMES to improve power system stability have been proposed. While fuzzy controller has proven its value in some applications, the researches applying fuzzy controller with ASMES have been actively reported. However, it is sometimes very difficult to specify the rule base for some plants, when the parameters change. To solve this problem, a fuzzy model reference learning controller (FMRLC) is proposed in this paper, which investigates multi-input multi-output FMRLC for time-variant nonlinear system. This control method provides the motivation for adaptive fuzzy control, where the focus is on the automatic online synthesis and tuning of fuzzy controller parameters (i.e., using online data to continually learn the fuzzy controller that will ensure that the performance objectives are met). Simulation results show that the proposed robust controller is able to work with nonlinear and nonstationary power system (i.e., single machine-infinite bus (SMIB) system), under various fault conditions and disturbances.     

鲁棒的双向多中继物理层安全传输方案

针对双向多中继系统物理层安全传输无法获取窃听者的精确信道状态信息（CSI）的问题,提出鲁棒的多中继协作波束形成和人工噪声联合物理层安全传输方案,以最大化系统总功率约束下信道状态"最差情况"时的安全总速率。在该方案中,待求解的问题是一个复杂的非凸优化问题。采用交替迭代和连续凸近似（SCA）方法,对波束形成向量、人工噪声协方差矩阵和源节点发射功率进行交替优化迭代,得到了问题的优化解。仿真实验验证了所提方案的有效性,并表明该方案具有更优的安全性能。     

判决反馈均衡器中用的改进RLS算法

在高速水声通信系统中,由于多径传播而引起的码间串扰ISI是传输误码率增加的主要原因。判决反馈均衡器（DFE）是对抗码间串扰ISI的有效方法。为了获得码间串扰为零的传输,固定遗忘因子的最小二乘递归算法（RLS）通常被用于更新DFE的抽头向量,但是这种算法在非稳定环境中并不能取得最佳表现。该文在获取均衡误差最小的即时过程中推导出一种应用在DFE中的自适应遗忘因子RLS算法。计算机仿真证明此方法对比以往的固定遗忘因子算法或可变遗忘因子算法获得了较好的传输表现。     

最小化具有无线携能通信的全双工中继系统发射功率和

考虑在无线网络中采用信息与能量同步传输来提高无线中继系统的性能,提出了基于无线射频网络中采用无线携能通信（SWIPT）技术的具有自能量回收的双向传输全双工中继系统。SWIPT应用在双向全双工中继系统中是一个新的尝试,其中能量受限的目的节点使用从中继和环路信道捕获的能量来发送反馈信息,并给出了全双工中继系统工作的逻辑结构和能量受限的目的节点的物理结构。然后,以最小化系统发射功率和作为优化目标来描述系统的性能,采用功率分配方案进行信息解码和能量捕获,应用半定规划、秩松弛和拉格朗日方法将原始非凸优化方程转化为可解凸优化问题并求解,且联合优化了中继发射功率、发射波束成形向量和功率分配比率。最后,实验仿真对比了所提的新系统与传统双向传输中继系统,结果验证了利用自能量回收不仅可以消除自干扰,而且可以显著优化系统发射功率和,且由于SWIPT技术与全双工中继系统的结合,使得所提出的系统比传统的双向传输系统具有更高的性能增益。     

认知网络中基于博弈论的联合功率控制与速率分配算法

针对认知无线网络上行链路中的资源分配问题,提出了一种适应于多小区认知无线网络的基于功率控制与速率分配的博弈算法。为了更加合理地控制用户的功率和速率,减小各次用户间的干扰,首先,在效用函数中分别给功率和速率设置了不同的代价因子,使其能够更加合理地控制用户,避免用户过度增加发射功率。其次,从理论上证明了该算法纳什均衡的存在性、唯一性以及算法的收敛性。最后,为了解决发射功率和传输速率的最优化问题,给出了联合功率控制和速率分配的迭代更新算法流程图。理论分析及仿真结果表明,与同类博弈算法相比,在保证通信质量的前提下,所提算法可以使得用户以较小的发射功率获得较大的传输速率和较高的信干噪比（SINR）,并且减小了用户间的干扰,提高了次用户系统容量。     

分布式双向中继系统的安全总速率优化

研究了分布式双向中继系统中的安全传输问题。为了优化系统总功率约束下的安全总速率,提出了基于人工噪声辅助的波束形成(Artificial-noise-aided beamforming,ANBF)发射方案。在ANBF方案中,待解决的问题是一个非凸的优化问题。为了求解该问题,分别采用连续参数凸近似算法(Sequential parametric convex approximation,SPCA)和牛顿迭代法,对波束形成向量,人工噪声的协方差矩阵和源节点发射功率进行交替优化迭代求解,最终得到局部最优解。可以证明,已有的未加人工噪声的常规波束形成(Beamforming,BF)方案和零空间波束形成(Null-space BF,NSBF)方案是ANBF方案的特例,后者使系统设计更具一般性。在仿真实验中,对比了ANBF方案与常规BF方案以及NSBF方案的安全性能,实验结果和性能分析验证了本文所提ANBF方案的有效性,并表明它具有最优的安全性能。     

Transmission power control techniques for wireless sensor networks

Communication is usually the most energy-consuming event in Wireless Sensor Networks (WSNs). One way to significantly reduce energy consumption is applying transmission power control (TPC) techniques to dynamically adjust the transmission power. This article presents two new TPC techniques for WSNs. The experimental evaluation compares the performance of the TCP techniques with B-MAC, the standard MAC protocol of the Mica 2 platform. These experiments take into account different distances among nodes, concurrent transmissions and node mobility. The new transmission power control techniques decrease energy consumption by up to 57% over B-MAC while maintaining the reliability of the channel. Under a low mobility scenario, the proposed protocols delivered up to 95% of the packets, showing that such methods are able to cope with node movement. We also show that the contention caused by higher transmission levels might be lower than analytical models suggest, due to the action of the capture effect.     

5G超密集异构网络带内无线回传资源分配方案

为实现5G超密集异构网络中无线回传链路和接入链路之间的最优资源分配,研究多用户场景下双层异构网络的联合用户调度和功率分配问题,在队列稳定和无线回传资源有限的情况下,综合考虑用户调度、功率分配和干扰控制等因素,对带内无线回传的最优资源分配问题进行数学建模并求解,基于李雅普诺夫优化理论提出联合用户调度和功率分配的优化算法。将优化问题解耦为网络内各个用户的调度以及宏基站和小基站的功率分配过程,采用MOSEK求解器和二分类方法获得用户调度向量,利用拉格朗日乘子法求解功率分配问题,并通过队列的时刻更新过程实现最优资源分配。仿真结果表明,在多用户场景下,该方案能够有效提升网络总吞吐量以及网络效用,并且毫米波频段的通信性能优于传统蜂窝网络频段。     

电力通信系统的宽带调节技术

当前利用分层网络结构对电力通信系统数字信道进行调节的方式,存在吞吐量性能差、宽带分配不均衡以及电力信息传输丢失严重等问题。提出利用遗传算法对电力通信系统宽带进行调节。对电力通信系统宽带中,每个OFDM符号内多个用户同时进行电力数据传输中的多种参数进行定义并计算,对最大的传输比特数以及最大功率进行计算,在电力通信资源分配速率的自适应和功率自适应的目标几乎一致理论基础上,建立电力通信多用户速率自适应宽带资源分配的数学模型,针对多用户的多目标特点,利用遗传算法中优良基因的注入,跨世代精英的保留以及迭代次数等,满足电力通信系统的多用户宽带资源分配需求。并通过实验证明,所提方法可实现电力通信系统宽带的有效调节。     

协作认知无线网络中基于功率分配的安全波束成形

在协作认知网络中,针对次用户作为转发中继时主用户信息容易被窃听的问题,本文提出了一种基于功率分配的安全波束成形设计方法。首先,根据任意转发波束成形功率占比,以次用户的传输速率最大化为优化目标,构建安全波束成形设计联合优化问题。然后,将所述目标优化问题转换为凸优化问题;最后,通过一维搜索转发波束成形功率占比获得全局最优解,完成认知无线网络的安全波束成形设计。仿真分析表明,本文所提方法在保证主用户信息安全的同时可实现次用户的传输速率最大化。     

Hybrid inter-cell interference management for ultra-dense heterogeneous network in 5G

The Ultra-dense Heterogeneous Network (HetNet), which consists of macro-cells and pico-cells, has been recognized as a key technique to improve network performance. However, the increasing number of pico-cells also causes severe interference including inter-cell interference and intra-cell interference. Therefore, interference management has become an important issue in ultra-dense HetNets, and the traditional enhanced inter-cell interference coordination (eICIC) scheme is no longer fit for the high density of small cells. In this paper, a hybrid interference management method based on dynamic eICIC and coordinated multi-point transmission (CoMP) is proposed. Firstly, a virtual cell is established based on the characteristics of ultra dense HetNets. Then, a novel joint dynamic eICIC scheme combined with multi-user beamforming is deployed to eliminate the inter-cell interference, and improve the throughput of virtual cell significantly without sharp decrease of throughput of macro-cell. Furthermore, a virtual cell based joint transmission scheme is deployed with a power control algorithm, which can obviously increase the spectrum efficiency of virtual cell edge. Simulation results verify that the proposed scheme can achieve better spectrum efficiency both at macro-cell and virtual cell edges, and the network throughput is also improved.     

认知无线电网络中感知时间与功率分配的优化

针对多协作用户多信道的情况,讨论了当信道增益固定时,各子信道之间检测时间、总检测时间与传输时间,以及各子信道之间功率分配的问题。区别于以往的单独优化算法,提出了各参数的联合优化算法。以信道容量为目标函数,给出了最优的时间和功率分配算法。实验结果表明,提出的算法能够实现频谱接入并且极大地提高了次用户系统的总信道容量。表明功率分配与信道上主用户占用的概率有关,而时间分配则与信道上主用户接收信噪比以及传输时自身的信噪比有关。在多认知用户网络中,参与合作的用户越多,接收与传输信噪比越高,次用户系统的总信道容量越大。对于认知无线电网络,还考虑了整体的实现。     

Robust power control method for wireless sensor networks with static output feedback

This paper proposed distributed strategies for the joint control of power and data rates in a wireless sensor network. By adapting a linear state-space model to describe the network dynamics, the power controller with static output feedback is designed in the case that the transmission signal are not always available and the estimation of the unmeasured states constitutes a crucial task in the network. The existence of the power controller is formulated as the feasibility of the convex optimization problem, which can be solved via a linear matrix inequality (LMI) approach. The proposed algorithm also caters to the uncertainties in the network dynamics. Numerical examples are given to illustrate the effectiveness of the proposed methods.     

Femtocell网络中基于联合传输的分簇与功率分配算法*

针对家庭基站(femtocell)密集部署时的下行干扰问题,提出一种基于多点协作联合传输的分簇与功率分配相结合的算法。首先根据受到的干扰程度进行分簇,将干扰强的家庭基站分到同一个簇,簇内所有家庭基站通过寻找对自身最有利的基站进行协作,将干扰信号转变有用信号,联合传输为用户提供服务,提升用户的信干噪比来保证用户性能,簇间则复用相同的频谱资源。然后通过给用户分配合适的功率使得总传输速率最大。仿真结果表示,所提算法能在抑制系统干扰的同时提高系统的吞吐量。     

Optimization of a robust collaborative-relay beamforming design for simultaneous wireless information and power transfer

We investigate a collaborative-relay beamforming design for simultaneous wireless information and power transfer. A non-robust beamforming design that assumes availability of perfect channel state information (CSI) in the relay nodes is addressed. In practical scenarios, CSI errors are usually inevitable; therefore, a robust collaborative-relay beamforming design is proposed. By applying the bisection method and the semidefinite relaxation (SDR) technique, the non-convex optimization problems of both non-robust and robust beamforming designs can be solved. Moreover, the solution returned by the SDR technique may not always be rank-one; thus, an iterative sub-gradient method is presented to acquire the rank-one solution. Simulation results show that under an imperfect CSI case, the proposed robust beamforming design can obtain a better performance than the non-robust one.     

考虑通信时滞和采样周期的电力系统负荷频率控制

针对电力系统负荷频率稳定控制问题,本文提出了一种时滞/采样相关的离散负荷频率控制(LFC)方案.首先,考虑通信网络传输时滞和反馈信号采样周期对系统的影响,建立闭环电力系统LFC模型.然后,基于建立的LFC模型,利用双边闭环Lyapunov泛函和LMI技术,提出了低保守性的时滞/采样相关稳定准则和控制器设计方法,确保所提控制方案能在一个较大的通信时滞和采样周期条件下保持电力系统稳定运行.最后,通过单区域和三区域电力系统验证所提方法的有效性.仿真结果表明,所设计LFC方案比现有其他LFC方案的控制性能更佳,鲁棒性更强,并且能在一定大小的通信时滞条件下提升电力系统的动态性能.