Gain scheduler middleware: a methodology to enable existing controllers for networked control and teleoperation - part I: networked control

Conventionally, in order to control an application over a data network, a specific networked control or teleoperation algorithm to compensate network delay effects is usually required for controller design. Therefore, an existing controller has to be redesigned or replaced by a new controller system. This replacement process is usually costly, inconvenient, and time consuming. In this paper, a novel methodology to enable existing controllers for networked control and teleoperation by middleware is introduced. The proposed methodology uses middleware to modify the output of an existing controller based on a gain scheduling algorithm with respect to the current network traffic conditions. Since the existing controller can still be utilized, this approach could save much time and investment cost. Two examples of the middleware applied for networked control and teleoperation with IP network delays are given in these two companion papers. Part I of these two companion papers introduces the concept of the proposed middleware approach. Formulation, delay modeling, and optimal gain finding based on a cost function for a case study on DC motor speed control with a proportional-integral (PI) controller are also described. Simulation results of the PI controller shows that, with the existence of IP network delays, the middleware can effectively maintain the networked control system performance and stabilize the system. Part II of this paper will cover the use of the proposed middleware concept for a mobile robot teleoperation.     

On the gain scheduling for networked PI controller over IP network

The potential use of networks for real-time high-performance control and automation is enormous and appealing. Replacing a widely used proportional-integral (PI) controller by a new networked controller for networked control capability can be costly and time-consuming. This paper proposes a methodology based on gain scheduling with respect to real-time IP traffic conditions to enhance the existing PI controller so it can be used over IP networks with a general network protocol like Ethernet. This paper first describes the gain scheduling approach based on constant network delays using a rational function approach. The formulation is extended to random IP network round-trip time (RTT) delays by using the generalized exponential distribution model. Simulation results show that the PI controller with gain scheduling provides significantly better networked control system performance.     

Wireless Internet access for mobile subscribers based on theGPRS/UMTS network

With the advent of IP technologies and the tremendous growth in data traffic, the wireless industry is evolving its core networks toward IP technology. Enabling wireless Internet access is one of the upcoming challenges for mobile radio network operators. The General Packet Radio Service is the packet-switched extension of GSM and was developed to facilitate access to IP-based services better than existing circuit-switched services provided by GSM. We illustrate how a visited mobile subscriber on a GPRS/UMTS network can access his/her home network via the gateway GPRS support node (GGSN). We also propose some implementation ideas on wireless Internet access for a remote mobile subscriber based on a GPRS/UMTS network     

The Complementary Use of 3G WCDMA and GSM/GPRS Cellular Radio Networks

The traffic performance of integrated 3G wide-band code division multiple access (WCDMA) and GSM/GPRS network is evaluated. This type of network links two cellular radio systems which have different set of frequency bands and the same coverage size. The base station of 3G WCDMA is installed on an existing GSM/GPRS site. Dual-mode mobile terminals use handoff to establish calls on the better system. The soft handoff or inter-frequency hard handoff occurs when mobile terminals of 3G WCDMA or GSM/GPRS move between two adjacent cells, respectively. The inter-system hard handoffs are used between 3G WCDMA and GSM/GPRS systems. The data rate conversions between different systems, soft handoff region size, multiple data rate multimedia services, and the effect of the mobile terminal mobility on the user mean dwell time in each system are considered in the study. The simulation results demonstrate that a great traffic performance improvement on the complementary use of 3G WCDMA and GSM/GPRS cellular radio networks compared with the use of GSM/GPRS cellular radio networks. When high-data rate transmission is chosen for low-mobility subscribers, both the handoff failure probability, and carried traffic rates increase with the new call generation rate. However, both rates decrease conversely with the increasing new call generation rate as soon as the new call generation rate exceeds a critical value. This causes the integrated networks saturation. The higher mean speed for the mobile terminals produces lower new call blocking probabilities and total carried traffic. The new call blocking probabilities and total carried traffic increase with the size of the soft handoff region.     

Performance analysis of the Cellular IP mobility protocol

The search for a suitable micromobility protocol which will inter-work with Mobile IP in 3G mobile networks has been the subject of intense research. Several proposals have been analyzed and comparisons carried out [1]. Cellular IP is a strong contender to take the seat as the chosen micromobility protocol, and its performance has been characterized mainly with Columbia IP Micromobility Software (CIPMS) under diverse scenarios. Previous analyses have considered generic TCP and UDP traffic. In the work presented here, a Cellular IP based 3G network model is developed, and services (voice, and web) are represented after probabilistic behaviors to conform, respectively, to a GSM coder, and web content comprised of packets, objects, and pages. In this way a more accurate knowledge of Cellular IP performance can be obtained.     

Path-tracking velocity control for robot manipulators with actuator constraints

An algorithm for high-performance path tracking for robot manipulators in the presence of model uncertainties and actuator constraints is presented. The path to be tracked is assumed given, and the nominal trajectories are computed using, for example, well-known algorithms for time-optimal path tracking. For online path tracking, the nominal, feedforward trajectories are combined with feedback in a control architecture with a secondary controller, such that robustness to uncertainties in model or environment is achieved. The control law is based on existing path-velocity control (PVC), or so called online time scaling, but in addition to speed adaptation along the tangent of the path, the algorithm also comprises an explicit formulation and approach, with several attractive properties, for handling the deviations along the transversal directions of the path. For achieving fast convergence along the normal and binormal directions of the path in 3D motion, the strategy proposed has inherent exponential convergence properties. The result is a complete architecture for path-tracking velocity control (PTVC). The method is evaluated in extensive simulations with manipulators of different complexity, and PTVC exhibits superior performance compared to PVC.     

"Ring-Ring" Might Soon Mean Ka-Ching

Readers of the technology industry tea leaves could reach one of two conclusions regarding widespread deployment of a global pay-by-mobile-phone infrastructure: either it so close it will be ubiquitous within three or four years or it so overhyped by mobile carriers that it could be a decade away. The GSM Association, the industry umbrella organization of GSM mobile network operators, announced two major initiatives in which mobile phones would serve as transaction devices. One is a mobile money transfer plan that would enable migrant workers to wire money back home to their families more quickly and easily than existing methods. The other is a worldwide "pay-buy mobile" initiative that would enable payment by mobile phones equipped with chips similar to those on smart cards     

移动IPv6切换时延优化新方法

移动IPv6中,移动节点(MN)在不同子网间移动时,既不中断与通信对端(CN)的通信,也不用改变其本身的IP地址.但是当MN与其家乡代理(HA)之间相距较远时,移动IPv6切换时延较大,对于实时性要求较高的业务无法适用.本文分析比较了目前移动IPv6常用的切换时延优化方法,提出了一种自适应快速层次移动IPv6切换时延优化方法,减小了移动IPv6切换时延,提高了网络的性能.     

Potential fraudulent usage in mobile telecommunications networks

This paper investigates the fraudulent usage of mobile telecommunications services due to cloned subscriber identity modules (SIMs). In GSM or the Universal Mobile Telecommunication System (UMTS), a mobile phone or mobile station uses its SIM to gain network access through authentication. If the SIM of a legal user is cloned, then the cloned SIM can be used for GSM/UMTS authentication and fraudulent usage may occur. Under the existing GSM/UMTS mobility management and call setup procedures, we show how quickly the fraudulent usage can be detected. We also propose a simple solution to speed up the detection of potential fraudulent usage.     

移动终端的定位跟踪系统研究与实现

定位跟踪技术是指通过特定的定位技术来获取移动手机或终端用户的位置信息(经度、纬度坐标等),并且在电子地图上对跟踪终端的位置进行标注的技术或服务。该系统综合使用了GPS定位技术、WEBGIS、GSM通信网络、GPRS无线分组技术、中间件等技术实现了对移动的终端进行定位跟踪的功能,实现对终端人员的实时跟踪和位置信息的动态管理。移动定位跟踪技术的主要应用场所有以下4种:追踪服务、信息服务、安全服务和付帐服务。     

Threshold-based congestion control for the SS7 signaling network inthe GSM digital cellular network

This paper considers the congestion control scheme for the SS7 signaling network in the group special mobile (GSM) digital cellular network. This congestion control scheme is based on monitoring the SS7 link buffer occupancy. In this scheme, a congestion onset message is sent to the user parts of the SS7 network when the buffer occupancy exceeds a certain threshold, and, subsequently, a congestion abatement message is sent when the buffer occupancy goes below another threshold. Upon receipt of the congestion onset message, the user parts are expected to “intelligently” throttle the user traffic (reduce the traffic rate) so as to yield speedy recovery from congestion. Subsequently, on receipt of the abatement message, the user traffic is restored to precongestion levels. This paper primarily proposes appropriate choice of throttles and an algorithmic procedure to size the thresholds so as to yield good performance during congestion. The paper also addresses some implementation issues related to the throttles. Finally, it considers the effects of delays for the onset and abatement messages in reaching the user parts on the performance and parameters of the congestion control scheme     

Supporting IP QoS in the General Packet Radio Service

The General Packet Radio Service is the current enhancement in the GSM infrastructure, capable of handling Internet protocol traffic for mobile computing and communications. A major deficiency of the current GPRS specification is the lack of adequate IP quality of service support. Two schemes for enhancing the GPRS architecture with the existing IP QoS support architectures, IntServ and DiffServ, are proposed. Solutions are proposed to the problem of establishing QoS reservations across the GPRS core network, and the required signaling enhancements and modifications in the components of the GPRS architecture are identified. Of the two proposed schemes the IntServ one requires frequent refreshing of state information and extra signaling. To quantify the effect that signaling overhead has on GPRS operation and performance, a simulation model of the proposed IntServ architecture was developed, which includes models of the GPRS cellular infrastructure, network traffic, and user movement. The obtained simulation results show that the proposed IntServ architecture demonstrated good scalability, even for large user populations     

频率重用技术干扰问题研究

随着移动通信技术的飞速发展和移动数据业务量的爆发性增长,全球多个国家开始了LTE的商用进程。随着LTE的进一步发展,现有2G网络将有部分频率重用于LTE,这必将带来LTE与GSM系统间的共存干扰,为了保证LTE与GSM系统能够正常运行,制定完善的邻频共存保护方案是频率重用技术需要解决的关键问题之一。本文通过对GSM与LTE系统间的邻频干扰问题进行深入研究,提出了不同LTE制式与GSM共存时的保护间隔方式,为频率重用技术的发展奠定了坚实的基础。     

vGPRS: A Mechanism for Voice over GPRS

This paper proposes vGPRS, a voice over IP (VoIP) mechanism for general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSC. Both standard GSM and GPRS mobile stations can be used to receive real-time VoIP service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, the message flows for vGPRS registration, call origination, call release and call termination procedures are described to show the feasibility of our vGPRS system.     

基于UMA技术的话音业务互切换技术的研究

在我国,中国移动已成为全球为数不多的几个同时拥有固定网络与移动网络的大运营商之一,如何充分利用固定网络资源与移动网络资源成为了全球通信业界研究的热点之一。本平台的目标是利用UMA技术有效的将Wi-Fi网络与TD-SCDMA网络和GSM网络结合在一起,实现三网融合,将话音业务和数据业务进行分流;由一个具有自主开发产权的UMA控制器(UNC)和双模手机构成。在不影响现有移动网络的基础上,通过增加UMA控制器,双模手机能够通过Wi-Fi网络无缝接入移动通信网络,实现WLAN、TD-SCDMA网络和GSM网络相互切换、漫游、无线上网等功能,移动用户不需改变号码即可享受该功能。     

Supporting real-time IP multimedia services in UMTS

UMTS, the successor of GSM, is evolving toward a future wireless all-IP network. We explain how it will support real-time IP multimedia services, as these services are expected to drive the adoption of wireless all-IP networks. We not only focus on the centerpiece of IP multimedia support, the IP multimedia subsystem, but also include the GPRS transport capabilities and OSA middleware capabilities. This helps to explain how the IMS fits in with, and builds upon, other pieces of the UMTS network. We analyze the pros and cons of providing IP multimedia session control capabilities as opposed to just providing basic IP connectivity, and highlight selected features of the IMS design for discussion.     

WCDMA核心网信令系统对七号信令网的影响

BICC和GCP是第三代移动网络中必不可少的信令,主要支持的承载网络是ATM和IP,许多厂商也侧重开发ATM和IP传输技术。在中国未来几年逐渐开展3G移动业务后,GSM网络的业务也可以逐渐连接到3G核心网络中,GSM也会支持分层网络,使用比STM更经济的IP作为传输,原来七号信令网络中的流量就会逐渐减少。在设计3G七号信令网络时,需要考虑3G网络信令对传输的要求,为将采用的新技术进行准备。     

GSM移动通信网络掉话解析

本文将全面分析GSM移动通信系统中导致各类掉话的原因。在移动通信中,掉话可分为两种形式：一类是在SDCCH信道上的掉话,一类是在TCH信道上的掉话。掉话率作为反映网络性能的一项重要指标,一直是网络优化工作关注的重点。     

Autonomous and teleoperation control of a mobile robot

The present work proposes an autonomous tracking control system and a control structure to combine autonomous and teleoperation commands in a bicycle-type mobile robot. This compounded operation renders great flexibility to the control system of the mobile robot. For autonomous operation, a simple tracking controller that includes compensation of the robot dynamics is developed. This tracking control system is proved to be stable in the sense that it asymptotically reaches the tracking objective. Teleoperation with visual access to the robot’s workspace is integrated via a joystick with the autonomous operation of the robot. Simulations and experimental results on a prototype robot show the feasibility and performance of the proposed control system.     

Designing a robust adaptive dynamic controller for nonholonomic mobile robots under modeling uncertainty and disturbances

The main stream of researches on the mobile robot is planning motions of the mobile robot under nonholonomic constraints. Much has been written about the problem of motion planning under nonholonomic constraints using only a kinematic model of a mobile robot. Those methods, however, assume that there is some kind of a dynamic controller that can produce perfectly the same velocity that is necessary for the kinematic controller. Also there is little literature on the robustness of the controller when there are uncertainties or external disturbances in the dynamical model of a mobile robot. In this paper, we proposed a robust adaptive controller that can achieve perfect velocity tracking while considering not only a kinematic model but also a dynamic model of the mobile robot. The proposed controller can overcome uncertainties and external disturbances by robust adaptive technique. The stability of the dynamic system will be shown through the Lyapunov method.