Source-based network-balanced receive power control with fixed base station assignment in cellular multimedia CDMA systems

In this paper, the receive power control (RPC) problem for users with different data rate and service requirements in a cellular code division multiple access (CDMA) system with fixed assignment of mobiles to base stations is analyzed. It is shown that the problem of RPC in a multi-cell multimedia system can be split into two optimization problems: source-based RPC (SBRPC) and network-balanced RPC (NBRPC). SBRPC determines the relative receive power levels (RPLs) between different classes in each cell irrespective of the intercell interference and is locally implemented. NBRPC determines the relative RPLs between cells, can be achieved by solving an eigenvalue problem with system-wide class-wise SIR balancing, and is globally implemented. It can be seen that minimizing the total mobile transmit power via interference balancing among base station receivers sets the reference RPLs for each class of users equally in each cell. An equivalent-bandwidth-based call admission control is also derived based on the solution to the RPC problem. Numerical results are presented to demonstrate the effectiveness of the RPC in a cellular multimedia CDMA system.     

视频网络中媒体流调度基本算法改进研究

媒体流的调度是视频网络中的一个核心问题,本文分析了在视频网络中媒体流调度传统基本算法-补丁算法的缺陷.根据媒体节目的不同组播流之间存在着一定的间隔,提出了一种引入周期常数,使一个媒体节目的不同组播流间隔必须为该周期常数的整数倍的改进算法,给出了改进算法的形式描述和流程图,总结了此算法的基本特点,提高了用户VCR操作的服务效率和补丁算法的公平性.通过仿真实验对改进算法的性能与几种基本算法进行了分析比较,并指出须进一步改进之处.     

Enhanced soft-handoff scheme for real-time streaming services in intelligent transportation systems based on CDMA

Code division multiple access (CDMA)-based radio-on-fiber road-vehicle communication systems were proposed to support real-time streaming services in intelligent transportation systems (ITSs). Soft handoff should be provided for real-time streaming services because these services are required to guarantee real-time property and quality of service (QoS). However, soft handoff of real-time streaming services causes the shortage of resource in view of the system. In this paper, the double-adjustment soft-handoff (DASH) scheme is proposed to support seamless service regardless of the shortage of resource and maximize the resource efficiency when real-time streaming services are served in CDMA-based ITSs. The DASH scheme adjusts the data rate of a call when it starts and finishes soft handoff. The performance of the DASH scheme is evaluated by analytical and simulation methods. Performances are evaluated with respect to the blocking probability, the handoff failure probability, and the carried traffic. Numerical results show that the proposed scheme can give relative good maintenance of calls and good throughput.     

Integrated rate, power and cell control in cellular CDMA systems: an interference-balancing approach

In this paper, a novel combined rate, power and cell control scheme that minimizes transmit bit energy while gracefully implementing the congestion control is proposed and studied. The reverse link in a code division multiple access (CDMA) system with a high degree of traffic fluctuation temporally as well as spatially is considered. The proposed radio resource management scheme attempts to reduce the interference power variation among base station antennas that can exist in a real radio network. Transmission rates of those users in the congested (non-congested) cells are decreased (increased); hence, the proposed scheme is appropriate for delay-insensitive variable-bit-rate applications. Minimization of average transmit bit energy is achieved, subject to maintenance of individual target Eb/I0 for each user. Two algorithms, one directly minimizing the transmit bit energy, and the other doing so indirectly using the measured pilot power, are presented. It can be shown that both algorithms select the optimal base station if forward- and reverse-link gains are reciprocal; however, the latter gain is decentralized and uses only the local measurements and is amenable for practical implementation.     

Rate control for streaming media transmission over WLAN

In order to solve the problems of link layer retransmission and packet fragment strategies for IEEE 802.11, this paper proposes a variable packet TCPfriendly rate control (VPTFRC) scheme for streaming media transmission over wireless local area network (WLAN) by researching on the policy of packet size adjustment in transport layer based on the minimum retransmit-delay constraint. Unlike other proposals, this process considers the impact of wireless packet error ratio (PER) on the packet size adjustment and the performance of rate control. Simulation results demonstrate that our proposed process can simultaneously achieve higher throughput, better fairness, shorter transmission delay and less jitter than TFRC. Among them, the ratio of delay, jitter and packet loss rate can reach a maximum improvement ratio of 58%, 42% and 85% respectively. __________ Translated from Journal of Huazhong University of Science and Technology (Nature Science Edition), 2007, 35(1): 1–3 [译自: 华中科技大学学报(自然科学版)]     

Performance evaluation of soft handoff for multimedia services in intelligent transportation systems based on CDMA

To support multimedia services in intelligent transportation systems (ITS), CDMA based radio-on-fiber road-vehicle communication systems were proposed. Soft handoff should be provided for multimedia services because these services are required to guarantee real-time property and quality of service (QoS). The performance evaluation of soft handoff is important in view of system management such as determination of optimal resource allocation, cell configuration, and admission strategy. But, the performance evaluation of soft handoff when multimedia services are serviced has not been previously researched, even though there have been some previous works for voice-call service. In this paper, we develop a new analytical model of soft handoff when multimedia services are served in CDMA based ITS. We evaluate the performance of soft handoff scheme by analytical and simulational method. Blocking probability, handoff failure probability and carried traffic are obtained.     

An adaptive resource reservation strategy for handoff in wireless CDMA cellular networks

A threshold-based adaptive resource reservation scheme for soft handoff calls in wireless code division multiple access (CDMA) cellular networks is proposed. The scheme gives handoff calls a higher admission priority than new calls, and is designed to adaptively adjust the reservation-request time threshold according to the varying traffic load. The individual reservation requests form a common reservation pool, and handoff calls are served on a first-come, first-served basis. With the proposed scheme, a minimum grade of service (GoS) in terms of new call blocking and handoff call dropping probabilities can be achieved. Simulation results are given to demonstrate the improvement in the GoS performance in comparison with other schemes.     

呼叫中心实现手机话务自动分配的新方案

针对目前社会上许多客服呼叫中心(包括举报、投诉中心等)普遍存在由于不能自动识别主叫手机用户所处位置，从而实现不了手机话务就近自动分配的问题，从呼叫中心一般的组网模式、与公网的互联现状出发，分析和阐述产生该问题的原因、给日常工作和手机用户造成的影响，以及传统的解决方案和所要付出的代价，并以温州电力客服中心的新解决方案为例，介绍其打破传统的解决思路，巧妙实现该功能的方法和成效。     

Joint admission control algorithm in access network

To deal with long probing delay and inaccurate probing results in the endpoint admission control method, a joint local and end-to-end admission control algorithm is proposed, which introduces local probing of access network besides end-to-end probing. Through local probing, the algorithm accurately estimated the resource status of the access network. Simulation shows that this algorithm can improve admission control performance and reduce users’ average waiting time when the access network is heavily loaded. __________ Translated from Journal of Beijing University of Posts and Telecommunications, 2007, 30(5): 9–12 [译自: 北京邮电大学学报]     

非自衡系统和不稳定系统的预测函数控制

针对非自衡系统和开环不稳定系统，结合预测函数控制、串级调节和PID控制三者的优点，提出了一种PFC-PID控制策略：内回路采用PID控制使对象稳定且快速消除内扰，外回路采用FPC控制，PFC的强鲁棒性保证了在对象特性变化的情况下仍然获得良好的调节品质。仿真结果显示了该控制策略的有效性。     

基于无差拍控制的PMSM电流预测控制算法

在传统的离散化矢量控制系统中,由于电流采样和PWM占空比更新等数字延时的存在,限制了PMSM控制系统在动态过程中对电机电流的控制能力.为了提高系统电流环性能拓展其带宽,在同步旋转轴系下,基于无差拍控制原理,提出了一种对电机电流的离散化预测控制算法.在理论上消除了矢量控制系统中的各种数字延时,提高了电机电流的控制能力.最后使用1台750 W的永磁同步伺服系统验证了这种算法的性能,实验结果表明永磁同步电机电流预测控制算法有效地提高了伺服系统电流环的动态性能和稳态精度.     

烘丝机烟丝含水率的预测PI控制

烘丝筒是具有较大热容的大滞后系统,出口烟丝水分含量相对于输入变量具有较强的非线性和滞后性:又由于入口烟丝水分含量波动等干扰,运用常规的PID算法难以达到期望的控制效果。采用预测PI控制算法对烟丝含水率控制系统进行改造,利用预测PI控制器的预测控制功能和PI控制功能,降低了出口烟丝水分含量的波动幅度,提高了卷烟生产质量。     

Predictive current control with current-error correction for PM brushless AC drives

The performance of the conventional predictive current control (PCC) when applied to a permanent-magnet brushless ac (PM BLAC) drive is analyzed. A technique is proposed to reduce the current errors that arise due to the inaccuracies in the system parameters and the nonideal behavior of the inverter during a steady-state operation. In addition, a current-regulated delta modulator is employed to achieve a fast dynamic response during a transient operation. The performance of the proposed PCC, which is simple to implement on a low-cost fixed-point DSP, is demonstrated experimentally.     

Predictive algorithm for the roll control autopilot of a jet fighter aircraft

Predictive controllers are often only applicable for open-loop stable systems. In this paper two such controllers are designed to operate on open-loop critically stable systems, each of which is used to find the control inputs for the roll control autopilot of a jet fighter aircraft. It is shown how it is quite possible for good predictive control to be achieved on open-loop critically stable systems.     

PID,Predictive and fuzzy temperature control for nuclear magnetic resonance spectroscopy experiments

Temperature control inside the probe of an NMR spectrometer is dealt with. First a simple model of the system is derived by means of step response experiments. Then four control algorithms are implemented and compared. Specifically, a PID regulator is first synthesized and applied to the real plant. Then, in order to cope with the non-linearity of the plant, two adaptive predictive control algorithms are implemented, namely the generalized predictive control and the constrained receding horizon predictive control algorithms. They both show superior performance with respect to PID for control of a simulated plant model and of the real plant. Finally a feasibility study is carried out for a fuzzy controller; its unsatisfactory behaviour in simulation prevents one from applying it to the plant.     

Autonomous driving control for ITS by using learning automaton network with multiple environments

In this paper, the application of the learning automaton (LA) network with multiple environments is proposed for the adaptive controller for ITS autonomous driving. The LA network, which we introduced previously, has the ability to learn which deals with both multiple reinforcement signals and information of multiple environments at the same time. This feature is found to be useful for improving the response of adaptation in dynamic environments such as highways. In order to evaluate the practical advantage of using the network, we designed a simulational highway system, constructed an autonomous travel controller using the simple LA and the LA network, and executed comparative experiments evaluating the performance of adaptation response and collision avoidance. The results show that the performance of the LA network with multiple environments is superior to that using simple LA application with regard to stability and safety. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 150(4): 36–43, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10363     

电压型PWM整流器模糊逻辑功率预测控制策略

根据PWM整流器在两相静止坐标系中的数学模型及瞬时功率理论,提出了一种瞬时功率预测方法,并结合模糊逻辑,改进了直接功率控制策略.该策略具有更好的动态性能,更快的响应速度.同时建立了基于MATLAB的PWM整流器仿真平台及研制了实验样机,通过仿真和实验结果验证了所提出的方法的可行性和有效性.     

多级给料粉状物料称重系统的预测控制算法

为解决粉状物料动态称重中称重速度和定量称重误差两者之间相互矛盾的问题,在应用动态称重传感器为基础的粉状物料定量包装机模型的基础上,采用预测控制算法,提出了多级给料系统中的控制算法,给出了整个进料过程在线动态辨识的方法,并对调整预测模型参数、估计切换系数、调整控制器的开关时机进行了探讨。实验结果表明,系统测量称重误差小于0．2％、定量速度达5～8次min。该方法能较好地对空中量进行预测控制,达到了减小误差的工程应用目的。     

Diagnostics for nonceramic insulators in harsh environments

One of the main reasons for using nonceramic insulators in polluted regions is the reduction of maintenance needed to keep a line in service. Because the useful lifetime of these insulators depends largely on the pollution conditions, it is advisable to inspect the insulators on a regular cycle. The article discusses several diagnostic techniques that can be applied to detect risky conditions before failure.