神经网络在CDMA移动通信上行链路功率控制中的应用研究

提出了一种神经网络功率控制方案，研究了该方案在码分多址(CDMA)移动通信中实现最小发送功率控制问题。首先导出了最小发送功率控制模型。而后，利用最陡下降方法得到了求解该模型的神经网络的原理框图，并分析了用该网络进行最小发送功率控制的基本理论和实际性能，探讨了该网络相关参数的确定方法。最后用计算机仿真法模拟出该方案的运行性能。仿真结果表明与最小功率分配算法相比，神经网络功率控制方案可以提高基站接收信号的平均信扰比，降低信扰比的平均偏差，提高信扰比达到目标信扰比90％以上的用户数量，从而可以降低用户信号的中断概率、提高信道容量。     

DFP算法在CDMA移动通信上行链路功率控制中的应用研究

本文提出了一种基于DFP算法的功率控制方案。详细研究了该方案在CDMA移动通信中,进行融合基站分配的上行链路功率控制的应用理论。首先导出了最小发送功率控制模型。而后,提出了用DFP算法求解该模型的原理框图,并分析了用该方案进行最小发送功率控制的基本理论和实际性能,探讨了该方案中进行一维搜索的方法。最后用计算机仿真法模拟出该方案的运行性能。结果表明与最小功率控制算法相比,DFP功率控制算法可以提高基站接收信号的平均信扰比,降低信扰比的平均偏差,减小信扰比低于目标信扰比一定比例的用户数量,从而可以降低用户信号的中断概率、提高信道容量。     

一种采用混合平衡准则的新功率控制算法

功率控制算法按准则可以分为基于功率平衡准则和基于SIR平衡准则两大主流。基于信干比平衡的功率控制算法存在正反馈问题。基于功率平衡和信干比平衡混合准则的功率控制算法可以解决正反馈问题,但复杂度较高,实现比较困难。提出了一种基于功率平衡和信干比平衡混合准则的功率控制算法。本算法在每次迭代中通过测试接收信号功率和接收信干比,只需要一次判决产生下一周期的发射功率,因此具有易于实现的优点。分析和仿真表明本算法是有效的。     

采用自抗扰控制的三电机同步协调系统

自抗扰控制器自问世以来被用于多种应用场合,但其有着参数多,难整定的弊端,文中依据RBF神经网络结构简单、逼近能力强的优势提出了基于RBF神经网络的复合自抗扰参数调节器,利用RBF神经网络获得自抗扰参数的在线调整信息,且将其应用于三电机同步系统,经过实验验证,该调节器能实时调节自抗扰参数且能改善控制性能,具有实用性。     

基于神经网络的列车自动驾驶控制算法研究

对列车自动驾驶系统的速度控制过程进行了分析,针对传统PID算法缺乏自适应能力的缺点,在传统神经网络算法的基础之上对神经元的学习算法作出改进,设计出了基于RBF网络辨识的单神经元自适应PID控制器,仿真结果表明该控制器能够满足列车自动驾驶系统速度控制要求。     

CDMA系统中的自适应反向闭环功率控制

在码分多址(CDMA)移动通信系统中,反向链路功率控制对克服远近效应和增加系统容量是非常重要的。本文提出了一种基于改进的神经网络(MNN)的自适应闭环功率控制算法,该方法平滑了移动信道衰落的影响,使基站接收到的小区中所有用户的信号功率相等。仿真结果表明,由于神经网络能够较好地识别反向链路的时变特性,MNN功率控制方法比传统的固定步长功率控制方法取得了更好的控制性能和系统容量。     

多输入多输出天线蜂窝系统中的分布式功率控制方法

在蜂窝无线通信系统设计中,基于信号干扰比(SIR)测量的功率控制方法得到广泛的应用。该文提出多输入多输出(MIMO)天线蜂窝系统中的基于SIR测量的分布式功率控制(DPC)方法。该方法通过控制移动台或者基站的发射功率可以达到以下两个目标的其中之一:(1)最小化所有基站或者移动台的平均接收SIR中断概率;(2)在满足目标SIR要求的前提下最小化平均发射功率。数值仿真结果显示,该文提出的DPC方法在低的计算复杂度下,可以达到降低SIR中断概率和减小发射功率的目的。     

CDMA系统中自适应反向闭环功率控制

在码分多址（ＣＤＭＡ）移动通信系统中，反向链路功率控制对克服“远近效应”和增加系统容量是非常重要的。本文提出了一种基于改进的神经网络（ＭＮＮ）的自适应闭环功率控制算法，该方法平滑了移动信道衰落的影响。使基站接收到的小区中所有用户的信号功率相等。仿真经结果表明，由于神经网络能够较好地识别反向链路的时变特性，ＭＮＮ功率控制方法比传统的固定步长功率控制方法取得了更好的控制性能和系统容量。     

基于信干比的认知无线电自适应功率控制算法

该文以空时编码(STBC) MC-CDMA网络系统为认知无线电通信平台,将一种基于SIR的非合作功率控制博弈算法应用于该认知无线电系统,并根据用户的SIR需求差异,对算法改进设计出新的自适应功率控制博弈算法(CR-NCPCG)。仿真结果表明CR-NCPCG算法以不同用户SIR需求为前提,通过不同用户功率的有效控制,实现了用户公平共享频谱资源的需求。     

基于RBF神经网络的永磁同步伺服电机控制系统

针对永磁同步电机控制系统,建立其磁场定向控制数学模型。运用增量式数字PID的方法实现对PMSM的传统PID控制策略。在此基础上,借助RBF神经网络的学习能力,进行PID控制器参数的自适应整定,进一步改善PID控制器的性能。同时,为提高RBF网络性能,采用粒子群算法对网络进行优化。仿真表明,与传统PID控制比较,基于RBF的PID控制系统能提高PID控制器的性能,改善了PMSM控制系统的收敛速度和跟踪精度。     

一种支持QoS的WCDMA混合神经网络反向链路功率控制算法

本文提出了一种混合神经网络反向链路功率控制算法,其外环控制采用Adaline神经网络模型,以不同业务的目标误帧率为指标,实时检测链路的误码状况,调整SIR目标值.内环控制采用Hopfield神经网络模型,通过控制移动台的发射功率确保SIR达到该目标值.与固定步长功率控制算法相比,该算法提高了控制精度和系统的稳定性,能够获得更高的通信质量.仿真实验也验证了算法的有效性.     

Achievable-SIR-based predictive closed-loop power control in a CDMAmobile system

A power control algorithm with two prediction models based on an achievable signal-to-interference power ratio (SIR) has been proposed under a multipath Rayleigh fading environment in a code-division multiple-access (CDMA) mobile system. An achievable SIR is defined as the maximum-minimum SIR among all users at a particular time step. The corresponding mobile transmission powers are denoted as the "optimum transmission powers." In the individual power predictor (IPP) model, a linear transversal filter is assigned to each user. The output of the IPP, which is a linear combination of the optimum transmission powers of the mobile during the current and previous power measurement periods, predicts the optimum transmission power of the mobile in the next time step. In the global power predictor (GPP) model, a single predictor, constructed by a linear neural network, is used to predict the optimum transmission powers of all mobiles in the next time step. In both predictor models, the weights of the predictors are updated by using the recursive least squares algorithm. To further improve the performance, a reduced power-measurement period has been studied. Simulation results show that the proposed power control algorithm can achieve a lower outage probability and a smaller dynamic range of transmission power compared with a conventional power control scheme     

多业务无线网络中基于最佳等信干比的功率控制

功率控制技术是无线网络的关键技术之一。为改进多业务无线网络中基于非合作博弈的功率控制算法中纳什均衡的帕累托有效性,引入数据终端的最佳等信干比概念,使得系统中所有数据终端都工作在最佳的等信干比下,语音终端工作在语音通信服务质量门限的目标信干比门限之下。推导出一个新的分布式基于最佳等信干比的功率控制算法。仿真表明,该算法明显提高了系统的服务质量,系统中终端均具有相对较高的效用和较低的发射功率,还使得无线网络资源的使用更加合理和公平。     

Optimal power control for Rayleigh-faded multiuser systems with outage constraints

How can we achieve the conflicting goals of reduced transmission power and increased capacity in a wireless network, without attempting to follow the instantaneous state of a fading channel? In this paper, we address this problem by jointly considering power control and multiuser detection (MUD) with outage-probability constraints in a Rayleigh fast-fading environment. The resulting power-control algorithms (PCAs) utilize the statistics of the channel and operate on a much slower timescale than traditional schemes. We propose an optimal iterative solution that is conceptually simple and finds the minimum sum power of all users while meeting their outage targets. Using a derived bound on outage probability, we introduce a mapping from outage to average signal-to-interference ratio (SIR) constraints. This allows us to propose a suboptimal iterative scheme that is a variation of an existing solution to a joint power control and MUD problem involving SIR constraints. We further use a recent result that transforms complex SIR expressions into a compact and decoupled form, to develop a noniterative and computationally inexpensive PCA for large systems of users. Simulation results are presented showing the closeness of the optimal and mapped schemes, speed of convergence, and performance comparisons.     

Unified Analysis for SIR-Based Power and Rate Control in Multipath Fading Channels

In this paper, we present a unified analysis on various signal-to-interference power ratio (SIR)-based power and rate control schemes in independent and nonidentical multipath fading channels. We study wireless direct sequence code division multiple access (DS-CDMA) systems with RAKE reception and derive new expressions for a mobile user's average SIR, average transmission power, and average data rate in terms of the probability distribution of the SIR. The performance of SIR-based combined power/rate control, power control, rate control, truncated power control, and truncated rate control schemes in independent and nonidentical Rayleigh fading channels is presented and compared. By substituting appropriate SIR distributions, this general mathematical framework can be applied to other fading channels such as the Nakagami, Rician, and lognormal channels     

Uplink power control for TDMA portable radio channels

Power control based on signal-to-interference ratio (SIR) has been proposed as a technique for managing co-channel interference in frequency reuse radio systems. Recently, new autonomous power control methods were introduced to achieve near-optimum performance without difficult centralized control proposed earlier. The achievable performance from preliminary studies appears promising for providing significant increase in spectrum efficiency. However, the implementation of the SIR-based power control algorithms remains challenging. In this paper, implementation of power control that indirectly depends on SIR is discussed. As an example, a simple closed-loop power control algorithm for the portable transmitter is introduced for TDMA portable radio systems. While it may appear specific for the system considered, the underlying principle and parameters required (i.e., error indicator, received power level, and signal quality indicator) are common to the implementation of digital demodulation circuitry. Computer simulations indicate that SIR level is maintained at a level suitable for sustaining desirable performance. Furthermore, when the power-control updating period is short, as in the specific system considered, moderate-rate short-term fading can be tracked and mitigated     

一种基于计费的WCDMA功率控制方法

在第三代移动通信系统中,为了有效地提高系统容量和通信质量,需要对无线资源如发射功率作合理的动态分配。该文通过研究 WCDMA系统中上行链路的干扰情况,推导得出 WCDMA系统的容量与业务性能指标的关系。通过定义网络资源份额,将功率控制问题转换为总量小于1的网络资源份额的分配问题。然后利用统一价格拍卖对网络资源份额进行最优配置,使得发射功率这一重要无线资源合理地分配给对其评价最高的用户业务。最后给出了上述算法的数值仿真。     

Traffic channel SIR estimation based on reverse pilot channel in cdma2000

Signal-to-Interference Ratio(SIR) is a very important metric of communication link quality. For wireless cellular systems, several control mechanisms, such as power control mechanisms, rate control mechanisms, and allocation of radio resource, are based on SIR estimation.In previous researches, most of researchers concentrated on WCDMA systems, in which pilot symbol is time-multiplexed with data symbol; the method developed in this case is not feasible for cdma2000 systems where pilot symbol is code-multiplexed with data symbol. This paper first develops the SIR estimators based on the reverse pilot channel and then derives the approximate analytic expression for its Mean Squared Error (MSE) function, the accuracy of which is validated through simulation. It is shown that the MSE of the new SIR estimator is significantly smaller than that of other widely used SIR estimators, especially in low SIR case. Finally, the estimate quality of the proposed method is further improved by long-termly averaging the sample interference.     

Autonomous SIR-based power control for a TDMA radio system

Power control based on signal-to-interference ratio (SIR) has been proposed as a technique for managing cochannel interference due to frequency reuse in a time-division multiple-access (TDMA) radio system. Early studies have focused on SIR balancing approaches that require centralized control for global power adjustment and/or associated channel reassignment or call admission control. This paper investigates the achievable performance of an autonomous power control technique which relies only on a simple fixed-step feedback adjustment algorithm. Simulation results, assuming no adaptation to Rayleigh fading, indicate that this simple power control technique can perform nearly as well as ideal SIR balancing/call removal, yielding a possible increase in spectrum efficiency of at least three times compared to a system without power control. Tracking of Rayleigh fading is found to provide an additional improvement in SIR of 4 to 4.5 dB for the range of fading rates expected in the pedestrian wireless access environments. This work is targeted toward understanding the traffic capacity and deployment implications of wireless technology alternatives that could provide access to local exchange networks.