Design of power controller in CDMA system with power and SIR error minimization

In this paper, an uplink power control problem is considered for code division multiple access (CDMA) systems. A distributed algorithm is proposed based on linear quadratic optimal control theory. The proposed scheme minimizes the sum of the power and the error of signal-to-interference ratio (SIR). A power controller is designed by constructing an optimization problem of a stochastic linear quadratic type in Krein space and solving a Kalman filter problem.     

Design of power controller in CDMA system with power and SIR error minimization

In this paper, an uplink power control problem is considered for code division multiple access (CDMA) systems. A distributed algorithm is proposed based on linear quadratic optimal control theory. The proposed scheme minimizes the sum of the power and the error of signal-to-interference ratio (SIR). A power controller is designed by constructing an optimization problem of a stochastic linear quadratic type in Krein space and solving a Kalman filter problem.     

基于粒子群的CDMA功率和速率联合控制算法

提出了基于效用函数的CDMA网络下行链路的功率和速率联合控制最优化算法.在这类算法中,效用函数为非凸函数,经典的最优化理论很难解决这类问题.将粒子群优化方法应用于算法的非凸性设计,并通过仿真算例证明了该算法能有效解决非凸优化问题,且可保证系统的公平性.     

均匀CDMA系统容量的设计与仿真

文章设计了较实用的有19个蜂窝小区的均匀CDMA实验系统业务中心的控制软件,并提出与距离的幂次有关的功率控制算法来节省基站的发射功率,及根据一天中不同时间区段的业务量对信道进行动态分配的方法提高系统容量。针对不同情况系统容量的计算机仿真结果表明:对小区基站采用功率控制算法可大大节省基站的发射功率。     

Design of Embedded Filters for Inner‐Loop Power Control in Wireless CDMA Communication Systems

We study inner‐loop power control for mobile wireless communication systems using code division multiple access transmission. We focus on the uplink, i.e., on communication from the mobile‐ to the base‐station, and show how to minimise the variance of the signal‐to‐interference ratio (SIR) tracking error through incorporation of recursive filters. These filters complement existing power controllers and are designed by using a linear model which takes into account quantisation of the power control signal, dynamics of channel gains, interference from other users, target SIR, and SIR estimation errors. Simulation results indicate that significant performance gains can be obtained, even in situations where the models used for design are only an approximation. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Scheduling multihop CDMA networks in the presence of secondary conflicts

This paper presents an algorithm for producing near-optimal conflict-free schedules for networks operating under code division multiple access (CDMA). A procedure for finding a lower bound on the length of such schedules is also presented. The presence of both primary and secondary conflicts (due to imperfectly orthogonal CDMA codes) are accounted for by these algorithms. The complexity of both algorithms is analyzed and computational experience with both procedures is presented. Using the lower bound, it is shown that the heuristic is effective. The complexity analysis demonstrates that it is efficient enough to use in networks of realistic size, even when the schedules must be produced in real time.This work was sponsored in part by the Naval Research Laboratory under Contract N00014-84-K-2011 and by the New York State Foundation for Science and Technology as part of its Centers for Advanced Technology Program.     

在CDMA蜂窝系统中实现无线电定位

随着ＣＤＭＡ蜂窝通信的推广应用和用户定位需求的日益增长,发展ＣＤＭＡ系统中的无线电定位技术已引起着广泛关注,在已取得了一定的进展。文中结合国内外最近几年的发展情况,讨论了无线电定位技术的应用方向,在ＣＤＭＡ系统中定位的方法及算法,影响定位精度的因素及克服方法。     

基于小波变换的CDMA图像盲水印算法

提出了一种盲扩展谱水印算法,将水印信息重复的嵌入到图像多层小波分解的系数中.通过对数字图像小波变换结构的研究和分析,利用扩展谱将信息嵌入到LH和HL子带,结合噪声视觉函数在水印的透明性和鲁棒性之间实现了较好的平衡,提高了信息隐藏的安全性,并运用CDMA(Code Division Multiple Access)理论实现了水印信息的盲提取.大量的试验结果表明,该算法对于常见的图像处理操作,特别是对于JPEG压缩和多种噪声攻击有较好的鲁棒性.     

Performance of multiuser CDMA system with space-time block coding in MIMO Rayleigh fading channels

In this paper, by introducing orthogonal space-time coding scheme, the multiuser CDMA systems with different space time codes are given, and corresponding system performance is investigated over Rayleigh fading channel. A low-complexity multiuser receiver scheme is developed for space-time coded CDMA systems. The scheme can make full use of the complex orthogonality of space-time coding to simplify the high decoding complexity of the existing scheme. Compared to the existing scheme with exponential decoding complexity, it has linear decoding complexity. Based on the performance analysis and mathematical calculation, average bit error rate (BER) of the system is derived in detail, and tight closed-form approximation expressions of BER are attained. Simulation results on average BER are in agreement with the theory analysis. The results show that the proposed scheme can achieve almost the same performance as the existing scheme. Moreover, on the condition of same system throughput and concatenation of channel code, the given full-rate space-time coded CDMA system has lower BER than the full-diversity space-time coded CDMA systems.     

基于智能天线的层次化CDMA移动通信网络设计

本文通过使用智能天线,给出高性能的层次化CDMA移动通信网络的设计策略。重点是对大区到小区所需的功率分析,大区智能天线模式分析以及小区天线倾斜角度对系统性能提高的影响。结论表明系统性能取决与小区位置和天线倾斜角度。通过定义干扰平衡因子得到最优的小区天线倾斜角度。     

A power system nonlinear adaptive decentralized controller design

In this paper, a novel excitation control is designed for improvement of transient stability of power systems. The control algorithm is based on the adaptive backstepping method in a recursive way without linearizing the system model. Lyapunov function method is applied in designing the controller to ensure the convergence of the power angle, relative speed of the generator and the active electrical power delivered by the generator when a large fault occurs. Compared with the existing nonlinear decentralized control approaches, the proposed controller has no requirement for the bounds of interconnections in the power system. And the new approach does not need the existence of solution of a designed algebraic Riccati equation. Furthermore, the transient stability performance of power systems can also be improved by the designed control approach. The efficacy of the designed controller has been demonstrated in a multimachine power system. Simulation results show transient stability enhancement of a power system in the face of a large sudden fault.     

Nonlinear control design for excitation controller and power system stabilizer

The paper focuses on the design of excitation controller and power system stabilizer (PSS) control schemes to enhance voltage regulation and transient stability. To design the excitation controller, the nonlinear models of the synchronous generator and electrical system are suitably arranged to give an input-output nonlinear model, which is subsequently made linear by a compensating law. The PSS control scheme is designed according to a new approach, based on the inverse system theory, which guarantees satisfactory swing damping by reducing the mutual influence between transient stability and voltage regulation. The results obtained by numerical simulations in different operating conditions confirm the effectiveness of the proposed design, also in the presence of model parameter inaccuracy.     

基于CDMA技术的FBG传感系统研究

基于码分多址(CDMA)技术,采用格雷互补序列对光源进行调制,使用相关运算对接收信号进行解调.该方法具有传感器间串音小和系统信噪比高等优点.基于该方法搭建了光纤Bragg光栅(FBG)传感实验平台,对其温度传感特性进行了实验研究.结果表明:系统具有温度响应线性度好和串音低的优点.     

带有CDMA短信模块的多功能电力监测仪

介绍了一款多功能电力监测仪,采集参数涵盖了除谐波以外的所有电网参数,监测仪嵌入CDMA通讯模块,利用模块的短信收发功能,将各种采集数据做远程传输。查询采集数据的设备可以是固定的电脑,也可以是一部手机,不受距离和地区限制,非常灵活方便。为了最大限度地降低运行费用,还可将单台监测仪作为主机,通过RS485总线连接若干台监测仪作为子机,组成电力采集网络,使多台监测仪共用一块CDMA通讯模块。这款电力监测仪已顺利通过各项EMC性能测试,并批量投放市场。     

随到接入流量模型用于时分接入系统的误差研究*

随到接入是多数流模型普遍采用的假定,实际通信系统中突发通常是时分接入的,这个差别对流模型精度造成多大影响常常是流模型研究中被忽视的问题,相关的论文至今为止几乎没有见到。为此就间断泊松模型（IPP）对这种误差作了研究,从数学根源上揭示了误差产生的原理,并推导出了时隙化IPP的动态均值流量与IPP模型的误差近似公式。仿真显示该理论结果与仿真值高度一致,相比IPP结果具有更高精度。     

IDMA系统中基于SNR演进和差分进化的功率优化研究

交织多址(IDMA)是一种依靠交织方式来区分多用户的多址接入技术。由于其性能在等功率分配和用户数较多时急剧下降,因此在IDMA系统中功率控制对提高系统性能尤为重要。提出了一种基于遗传算法的新型功率优化策略,该算法利用差分进化(DE)和SNR演进方法来实现IDMA的功率控制,所得结果与之前线性规划(LP)算法的相当,但是避免了LP算法中需要量化和分组变量以及需要使用步进参数等缺点。     

Quality of service estimation for soft handoff region ratio and call admission control in CDMA cellular systems

In the operational stage of code division multiple access (CDMA) systems, the soft handoff region ratio (SHRR) is among the important parameters that guarantee the quality of service (QoS) and resource allocation. This paper analytically investigates the effects of the SHRR on QoS. In doing so, we simultaneously take into account the capacity increasing factor and traffic load variation. For this purpose, we propose a new traffic load estimation model using a semi-Markov chain in order to consider the call arrivals influenced by the SHRR under general resident time condition. We also present the calculation algorithm of the QoS measures such as the new call blocking probability (NBP) and forced termination probability (FTP) by applying the proposed model to the prioritized call admission control (CAC). The numerical result illustrates the effects of various soft handoff system parameters. Likewise, it shows that the value of SHRR has a significant impact of the QoS under the normal propagation conditions. Sensitivity analysis is also performed to show the effect of exponential cell resident time assumption. The proposed modeling is expected to provide a practical guide to improve the QoS of CDMA soft handoff systems.     

点对多点通信中多用户检测的实现

文章对扩频通信芯片STEL2000进行了研究,并用它实现了点对多点通信中的多用户检测实验。实验结果表明:采用CDMA技术的系统,无论是对白噪声干扰和中频干扰都有很强的抗干扰能力。     

CDMA系统中的一种分布式功率控制算法

通过仿真、对比分析了一种基于效益函数的博弈功率控制（UBPC）算法与DPC功率控制算法用于CDMA系统的性能。结果表明恰当选择效益函数和代价函数后,博弈功率控制算法可解决DPC算法因用户数的增加而发散的问题,并且可以保证用户的QoS要求及用户间的公平性,同时算法的收敛速度对用户数不敏感。     

A modified direct adaptive robust motion trajectory tracking controller of a pneumatic system

In this study, we developed and tested a high-precision motion trajectory tracking controller of a pneumatic cylinder driven by four costless on/off solenoid valves rather than by a proportional directional control valve. The relationship between the pulse width modulation （PWM） of a signal＇s duty cycle and control law was determined experimentally, and a mathematical model of the whole system established. Owing to unknown disturbances and unmodeled dynamics, there are considerable uncertain nonlinearities and parametric uncertainties in this pneumatic system. A modified direct adaptive robust controller （DARC） was constructed to cope with these issues. The controller employs a gradient type adaptation law based on discontinuous projection mapping to guarantee that estimated unknown model parameters stay within a known bounded region, and uses a deterministic robust control strategy to weaken the effects of unmodeled dynamics, disturbances, and parameter estimation errors. By using discontinuous projection mapping, the parameter adaptation law and the robust control law can be synthesized separately. A recursive backstepping technology is applied to account for unmatched model uncertainties. Kalman filters were designed sepa- rately to estimate the motion states and the derivative of the intermediate control law in synthesizing the deterministic robust control law. Experimental results illustrate the effectiveness of the proposed controller.