An icon-based approach to system control development

The implementation of an icon-based manufacturing message specification (MMS) messaging system for system control in a manufacturing automation protocol (MAP environment) is described. The system was designed with a four-layer hierarchy. The top layer acts as a user interface and essentially provides a data manipulation service. The next layer invokes the appropriate firmware calls to manage the communication process. The third layer consists of the firmware that handles the actual transmission of data across the network. The lowest level is the actual network hardware. Twelve MMS services were implemented in order to provide the capability to carry out a typical control session. The system was tested using software that simulates the external communications of an MMS virtual manufacturing device. The LabVIEW MAP environment used imposed at least two limitations on the operation of the system. First, LabVIEW makes no provision for data structures; therefore, each parameter had to be passed from the MMS layer to the code VI layer as a variable of a specific data type. Second, LabVIEW provides no convenient way to maintain global variables throughout a diagram     

MMS发送关键技术研究

随着TD-SCDMA网络建设的不断完善,在3G网络上的多媒体业务有着广泛的应用前景.根据在TD-SCDMA网络中基于WAP协议成功实现MMS(彩信)发送的实例,本文介绍了WAP协议产生的背景及其结构,彩信MMS PDU封装格式,详细说明了客户端与WAP网关的连接、中文字符的编解码、图像格式、SMIL语言应用等关键性问题.同时给出了发送实例中MMS PDU的结构图,清晰的说明了MMS(彩信)发送中的封装格式,并针对相应的问题提出了解决方案.     

MMS(多媒体短消息业务)及其实现

MMS是3GPP和WAP论坛制订的移动数据业务。与SMS相比，它除了可以发送简单文本消息外还可以发送图像、音频、视频、动画等多媒体信息内容。文中对MMS的体系结构进行了介绍，对MMS系统两种实现方式：基于WAP的实现和基于IP的实现进行了探讨，最后还对MMS业务的部署进行了讨论。     

An Exposition of Performance-Security Trade-offs in RANETs Based on Quantitative Network Models

Security mechanisms, such as encryption and authentication protocols, require extra computing resources and therefore, have an adverse effect upon the performance of robotic mobile wireless ad hoc networks (RANETs). Thus, an optimal performance and security trade-off should be one of the main aspects that should be taken into consideration during the design, development, tuning and upgrading of such networks. In this context, an exposition is initially undertaken on the applicability of Petri nets (PNs) and queueing networks (QNs) in conjunction with their generalisations and hybrid integrations as robust quantitative modelling tools for the performance analysis of discrete flow systems, such as computer systems, communication networks and manufacturing systems. To overcome some of the inherent limitations of these models, a novel hybrid modelling framework is explored for the quantitative evaluation of RANETs, where each robotic node is represented by an abstract open hybrid G-GSPN_QN model with head-of-line priorities, subject to combined performance and security metrics (CPSMs). The proposed model focuses on security processing and state-based control and it is based on an open generalised stochastic PN (GSPN) with a gated multi-class ‘On–Off’ traffic and mobility model. Moreover, it employs a power consumption model and is linked in tandem with an arbitrary QN consisting of finite capacity channel queues with blocking for ‘intra’ robot component-to-component communication and ‘inter’ robot-to-robot transmission. Conclusions and future research directions are included.     

Mobility Modeling for Personal Networks

A Personal Network (PN) is a user-centric design interconnecting numerous devices belonging to a user in different geographic locations, such as home, office, car, etc., to form a single global network to offer fully personalized services. In PNs devices of the user move in different groups, where these groups merge and split. In this paper, we design and simulate a PN Mobility Model (PNMM) to capture the characteristics of movements of devices in PNs. We propose a simple stability evaluation method for group mobility models and apply the method to PNMM. Through the stability evaluation, we find that PNMM possesses long-term steady state behavior. Moreover, for the evaluation of mobility models, some evaluation methods have been proposed, which include non-homogenous node mobility, relative node mobility in a group, and dynamics of group merging and splitting. Analysis shows that PNMM is better than other models to represent the PN mobility properties. In addition, the impact of PNMM on the performance of a PN Clustering Protocol (PNCP) has been studied. Simulation results provide insights into the performance of PNCP, and provide guidelines for future design of PN clustering. PNMM can be easily applied to any Personal Area Network or Body Area Network with slight modifications.     

移动智能网多媒体消息业务的体系结构及其协议

多媒体消息业务(MMS，multimedia messaging service)作为一种新的移动数据业务已经得到了大规模的应用，在移动智能网上也可以支持这种业务。ITU-T、ETSI对移动智能网支持MMS并无相应的规范，目前国内计划采用的是SCP(service control point)与MMSC(multimedia messaging service center)互联的解决方案。本文在对此方案做详细分析的同时，提出了基于CAMEL(customized application for mobile enhanced logic)的MMS体系结构，并对此进行了深入的探讨。在此基础上，分析计算了智能多媒体消息业务对SCP及信令链路造成的影响。     

Application of Petri Nets and Lagrangian Relaxation to Scheduling Automatic Material-Handling Vehicles in 300-mm Semiconductor Manufacturing

This paper deals with vehicle-scheduling problem (VSP) in an automatic material-handling environment in 300-mm semiconductor wafer manufacturing. We adopt Petri nets (PNs) modeling techniques to model the complicated coupling dynamics among transport jobs and overhead hoist transport (OHT) vehicles in a 300-mm OHT loop. The congestion phenomenon among OHT vehicles is captured. With help of the PN models, we formulate the OHT VSP as an integer programming problem whose objective is to schedule OHT vehicles to transport jobs such that average job completion time is minimized. Instead of solving for the optimal solution, we develop a solution methodology to generate a feasible schedule efficiently. A Lagrangian relaxation step is first taken to decompose the PN-based, integer programming problem into individual job-scheduling subproblems. To reduce computation efforts in solving each subproblem optimally, we develop an approximation method to solve each job subproblem by utilizing a reduced PN model of the job. Lagrangian multipliers are then optimized by a surrogate subgradient method. A heuristic algorithm is developed to adjust the dual solution to a feasible schedule. Numerical results demonstrate that our solution methodology can generate good schedules within a reasonable amount of computation time for realistic problems. Compared to a popular vehicle-dispatching rule, our approach can achieve in average 32% improvements on the average delivery time in our realistic test cases.     

Performance evaluation of MiniMAP networks

A simulation study of the performances of MiniMAP networks is presented. The two network models used in the simulation take into account the effect of the maximum number of outstanding requests set for each manufacturing message specification (MMS) application association. Three different situations are considered. In the first, all the messages are generated at the same priority level, whereas in the other two, four priority classes that are directly mapped onto channel priorities are introduced. However, the second situation considers the use of priorities only on the client side of MMS, whereas the third uses priorities on both sides     

Transporting data between wireless applications using a messaging system—MMS

There is a demand for using messaging systems to transport data between wireless applications in mobile communications. As multimedia messaging service (MMS) is a promising messaging system to meet the demand, it is under enhancement in related standardization bodies to make it effective in transporting application data. The enhancement should be compatible with the existing MMS services for its smooth and safe deployment. This paper proposes a solution to make the enhancement backward compatible, so that a new MMS service of transporting application data has no impact on the existing MMS services. The solution also provides forward compatibility, so that an MMS service of transporting application data does not hinder the introduction of any application in the future, allowing instantaneous deployment of a wireless application. The standardization bodies did not define any format for data communication between a wireless application and MMS in a terminal. A common format in this regard would help mass availability of wireless applications for different purposes independent of manufacturing a mobile terminal. Based on an analysis described in this paper, eXtensible Markup Language (XML) is the suitable format for the purpose. This paper also presents examples of XML file to indicate what data should be communicated in this regard. Copyright © 2006 John Wiley & Sons, Ltd.     

Modular design principles for protocols with an application to thetransport layer

A method for specifying services, specifying protocols, and constructing protocol specifications by stepwise refinement of service specifications is presented. The method is based on assertional reasoning and a refinement relation between state transition systems. The method is demonstrated on the transport layer, which is used by application protocols such as electronic mail, file transfer, remote login, etc. A succession of specifications is constructed, starting from a very abstract transport service and culminating in specific transport protocols comparable to TCP and ISO TP4. Each specification offers both connection management and connection-specific data transfer. It is shown how any connection-independent data transfer protocol can be transformed to offer connection-specific data transfer service     

Battery-aware Routing in Personal Networks

A personal network (PN) is a network of devices belonging to a person. It can consist of a number of ad hoc sub-networks which are linked together through the Internet. We study battery-aware routing for multi-hop connectivity in sub-networks of PNs, and propose a new algorithm. The proposed algorithm takes the advantage of having mains-connected devices in a PN to direct the traffic to such devices and avoid relaying over nodes with low battery energy. A consequence of this strategy is directing the traffic load to static nodes of the network as well, since mains-connected nodes are static while battery-powered nodes could be mobile. This results in less route failures due to less mobility of nodes along a chosen path. We comprehensively compare the performance of our proposed algorithm with the performance of some well-known algorithms from the literature. We consider the effect of node density, routing overhead, heterogeneity of nodes in terms of their power supplies, gateway-oriented communication, mobility of nodes, and transmission power control, on the performance of battery-aware routing algorithms in PNs. Taking into account various parameters and different scenarios, we show that directing the traffic to mains-powered nodes can profoundly increase operational lifetime of the network. Our algorithm, as well as the results of our work, can also be applied to other types of ad hoc networks with heterogeneous power supplies.     

Concepts, services, and protocols of the new GSM phase 2+ generalpacket radio service

For almost three years the European Telecommunications Standards Institute (ETSI) has been working on the specification of the general packet radio service (GPRS) for the Global System for Mobile Communications (GSM). In the course of 1997 standardization will come to an end, and a first introduction of GPRS by a service provider or network operator is likely to take place in 1999. The new service will accommodate data connections with variable bit rates and high bandwidth efficiency, and thus offers the possibility to attract a wide range of new applications to GSM networks. In this article possible applications and elementary concepts and service characteristics of GPRS are explained in detail. Furthermore, a medium access control protocol that conforms to the draft standard proposal for the GPRS air interface is introduced and analyzed. Thereafter, the simulation model is described and simulation results presented. The performance analysis carried out shows reasonable performance even under high load conditions     

Automated Verification of the Connection Management Aspects of the IEEE 802.2 Logical Link Control Protocol

This paper discusses the verification of the connection management aspects of the IEEE 802.2 logical link control (LLC) protocol standard for local area networks. An automated protocol development technique is used to verify a subset of the protocol with respect to the protocol properties of completeness, deadlock freeness, boundedness, and termination. These properties are found to hold for the subset of the protocol analyzed here. The technique is also used to derive user event sequences for some interesting subsets of the protocol. These user event sequences together make up a partial service specification of the protocol.     

Modeling resource management in cellular systems using Petri nets

Modeling and analysis tools are essential for the design and evaluation of complex systems. This is particularly true for cellular systems, where, for instance, a variety of handoff, channel allocation, and data-transmission algorithms have been proposed. The capabilities of Petri nets (PNs) are used as a novel approach in the analysis of handoff, dynamic channel allocation (DCA), and cellular digital packet data resource management problems. The generalized stochastic PN (GSPN) models are obtained and analyzed as continuous-time Markov chains (MCs) derived from the reachability graphs. Solution of the MC results in performance indicators, which show the impacts of different algorithms on the system behavior     

MMS国际漫游方案浅析

目前，MMS国际漫游有2种可供选择的方案：直连方案和通过由第三方经营的GRX网络建立连接的GRX方案。直连方案适用于业务量较为集中的运营商之间或短期快速互联的要求；GRX方案通用于长期MMS业务国际漫游的要求。另外，在GRX方案中，还应注意解决DNS／ENUM、计费和结算．QoS等问题。     

Jini to the rescue [computer network interconnection technology]

A new approach to creating networks could simplify their construction end adaptation-if some kinks in the current specification can be remedied and missing features added. At the center of Jini connection technology is a lookup service, which resides on a server in a network. Its job is to act as a central market for Jini services scattered around the network, grouping similar ones together and making them accessible to client application programs. To become part of the market, a service first uses the discovery protocol to find a lookup service and then uses the join protocol to register and thus become available to client applications. Once clients and services are paired up, they no longer need the lookup service's assistance and can work together directly     

Research Issues in Ad-Hoc Distributed Personal Networking

This paper discusses the research issues that need to be addressed in order to create a personal distributed environment where people interact with various companion, embedded, or invisible computers not only in their close vicinity but potentially anywhere. These systems are called personal networks (PNs). They constitute a category of distributed systems with very specific characteristics. They are configured in an ad hoc fashion, as the opportunity and the demand arise, to support personal applications. PNs consist of communicating clusters of personal digital devices, devices shared with other people and even infrastructure-based systems. At the heart of a PN is a core Personal Area Network (PAN), which is physically associated with the owner of the PN. Unlike the present PANs that have a geographically limited coverage, the Personal Operating Space, PNs have an unrestricted geographical span, and incorporate devices into the personal environment regardless of their geographic location. In order to do this they need the services of infrastructure-based networks and ad-hoc networks to extend their reach. A PN extends and complements the concept of pervasive computing. We show that PNs introduce new design challenges due to the heterogeneity of the involved technologies, the need for self-organization, the dynamics of the system composition, the application-driven nature, the co-operation with infrastructure-based networks, and the security hazards. We discuss the impact of these problems on network design, assess present and proposed solutions, and identify the research issues. This revised version was published online in August 2006 with corrections to the Cover Date.     

A generalized protection framework using a new link-State availability model for reliable optical networks

This paper investigates a generalized protection framework for availability-guaranteed connection provisioning in an optical wavelength-division-multiplexed (WDM) network. Reliability is a crucial concern in high-speed optical networks. A service level agreement (SLA), which mandates high service availability even in the face of network failures must be met in provisioning a reliable connection. In this study, a new link-state-modeling mechanism is developed to form a dynamic link-state parameter called link and resource availability (LRA), which represents physical-layer availability and resource status for an optical link. Such up-to-date link-state information can be used by a standard link-state routing protocol to efficiently provision reliable connections. Based on the link-state availability model, LRA, a connection-provisioning algorithm is then proposed which can guarantee customers' availability requirements. A new generalized protection model is developed through dynamic LRA-based provisioning. Numerical results demonstrate the performance of the proposed provisioning approach to be promising.     

Design of industrial automated systems via relay ladder logicprogramming and Petri nets

For the past few decades, programmable logic controllers (PLCs) using relay ladder logic (RLL) programming have been the workhorse for controlling event-driven industrial automated systems. RLL proved to be flexible compared to the hardwired RLL control implementation, due to its feature of software implementation. As automated systems become more complex, they also become more difficult to understand and maintain. It takes tremendous effort to accommodate specification changes (which are becoming frequent) to meet today's flexible automation needs. Several methods are emerging to overcome the shortcomings of RLL. Petri nets (PNs), initially proposed as a modeling tool, have been developed as such a method. This paper adopts an industrial-scale system to compare RLL and PN design methods so that the advantages of PN-like approaches are fully recognized. The criteria are: (i) the understandability that relates to the ability to evaluate the programmed logic, to verify its correctness and to maintain the control system, and (ii) the flexibility that relates to the easy modification of logic when the specification changes. This network takes an existing industrial system, conducts discrete event control designs by using both RLL programming and PN methods, and performs a comparative study on them. Together with previous comparison results using small-scale systems, the results of this study support that PN-like advanced discrete event control design methods are better than RLL in terms of the understandability and flexibility of the resulting control design