Showing papers in "Bell Labs Technical Journal in 2006"

Critical national infrastructure reliability modeling and analysis

Abstract: One of the top 10 priorities of the U.S. Department of Homeland Security is protection of our critical national infrastructures including power, communications, transportation, and water. This paper presents models to quantify the interdependencies of critical infrastructures in the U.S. and evaluate plans to compensate for vulnerabilities. Communications is a key infrastructure, central to all others, so that understanding and modeling the risk due to communications disruptions is a high priority in order to enhance public safety and infrastructure resiliency. This paper discusses reliability modeling and analysis at a higher level than usual. Reliability analysis typically deals at the component or sub-system level and talks about “mean time to failure” and “mean time to repair” to derive availability estimates of equipment. Here, we deal with aggregate scales of failures, restoration, and mitigation across national infrastructures. This aggregate scale is useful when examining multiple infrastructures simultaneously with their interdependencies. System dynamics simulation models have been created for both communication networks and for the infrastructure interaction models that quantify these interactions using a risk-informed decision process for the evaluation of alternate protective measures and investment strategies in support of critical infrastructure protection. We will describe an example development of these coupled infrastructure consequence models and their application to the analysis of a power disruption and its cascading effect on the telecommunications infrastructure as well as the emergency services infrastructure. The results show significant impacts across infrastructures that can become increasingly exacerbated if the consumer population moves more and more to telecom services without power lifeline.

LambdaXtreme® transport system: R&D of a high capacity system for low cost, ultra long haul DWDM transport

Abstract: The LambdaXtreme® Transport System, Lucent Technologies' ultra long haul high-capacity transport product, leverages leading edge innovations in optics and applied physics as well as computational and computer science. In this paper, we provide a detailed view of the research and development efforts that resulted in a lightwave transmission system that is now being used in backbone national networks in the United States.

Wavelength selective switching for optical bandwidth management

Abstract: Optical transport capacities have grown significantly in the last decade to meet the increased demands on communications networks. This growth has been achieved both by increases in individual channel rates, which are based on time division multiplexing (TDM), and by increased channel counts, through the use of dense wavelength division multiplexing (DWDM). Yet increasing optical transport capacity alone is insufficient to scale the network; the underlying data needs to be delivered from numerous geographically diverse originating locations to similarly diverse terminating locations, requiring increasing switching capacity to facilitate this networking need. Since the growth in the individual TDM channel rates is driven by the capabilities of electronics, it is reasonable to expect that the switching capacity of electronics will tend to track this trend, although because of the challenges in high data rate interconnects it is unlikely to exceed it. This leaves the challenge of managing the increased bandwidth attained through the use of DWDM. Management of this bandwidth in the optical layer is an attractive proposition if eliminating unnecessary high-speed electronics in the path of an optical signal can reduce the complexity of the network and the associated equipment costs. These optical bandwidth management elements are classified according to the degree of switching, as either reconfigurable optical add/drop multiplexers (ROADM) or wavelength selective cross-connects (WSXC), analogous to the add/drop multiplexers and digital cross-connects of the TDM domain. We generalize these elements and describe whether the switching provides functions that are multicolored, colorless, or colored, and whether the channels are fixed data rate or rateless. We review the wavelength selective switch (WSS) components that perform the necessary switching function and present two successful technology platforms that can be used to construct them: planar lightwave circuits (PLC) and micro-electromechanical systems (MEMS). We also discuss future directions for WSS technologies and device functionality to more flexibly manage bandwidth in the optical layer.

Enabling new services by exploiting presence and context information in IMS

Abstract: The IP Multimedia Subsystem (IMS) architecture enables a new class of converged, multimedia services for subscribers. This paper examines the role of presence information in IMS to provide personalized treatment of voice over Internet Protocol (VoIP) calls, multimedia sessions, and instant messaging (IM) interactions. This can be achieved with an IMS application server that interacts in a standardized way with IMS elements (S-CSCF and HSS) and other elements such as the MiLife™ presence server. In addition, we propose a generalized architecture that extends the presence concept to a broader class of context information. Based on selected use cases, we identify required presence and context attributes (e.g., source, real-time availability, and lifetime) and their characteristics. This paper also addresses how these attributes can be gathered, monitored, filtered, and stored efficiently using a hierarchical architecture. This includes incorporation of external presence and context information, such as emergency and enterprise calendar data, in a secure and privacy-sensitive manner.

Design tools for transparent optical networks

Abstract: Optical technology promises to revolutionize data networking by providing enormous bandwidth for data transport at minimal cost. A key to cost reduction is to increase transparency, that is, to keep a data stream encoded as an optical signal for as long as possible. Wavelength switching increases transparency by allowing different data streams, each encoded in a different wavelength of light, to be independently routed through an optical network. We discuss Bell Labs-developed software tools that help design wavelength-switched optical networks. The software tools simultaneously minimize the cost of the designed network, reduce the time and cost to perform the design, and ensure compliance with engineering constraints. The tools span three levels of abstraction, from routing and reconfigurable add/drop multiplexer (ROADM) choice, to span engineering, to power dynamics simulation. Each level represents a different tradeoff between design scope and level of detail. For each class of tool, we briefly describe design philosophy, algorithms, performance, and resulting value for Lucent's customers.

Presence and availability with IMS: Applications architecture, traffic analysis, and capacity impacts

Abstract: A key advantage of the IP Multimedia Subsystem (IMS) is that it promotes the development of innovative multimedia services designed to bring an enhanced experience to the end user. The presenceand availability service is viewed as an indispensable feature for these next-generation services to help service providers generate new revenue and reduce churn. Numerous new services are currently being designed to take advantage of this feature. In this paper, we examine presence and availability in the context of IMS and describe its architecture as defined by the 3rd Generation Partnership Project/3rd Generation Partnership Project 2 (3GPP/3GPP2) and the Internet Engineering Task Force (IETF). In addition, we provide an analysis of presence updates and propose a user model and a traffic model to quantify the signaling traffic that such a feature can generate on a network. Through this model, network designers can examine the processing requirements for presence servers and other IMS components (i.e., call session control function [CSCF]) as well as the cost of transporting such traffic in the network.

Warranty cost models considering imperfect repair and preventive maintenance

Abstract: Today most products are sold with a warranty that offers financial protection to consumers due to failures during the warranty period. Depending on the type of product, its inherent quality/reliability, and a host of other variables including the warranty period, warranty cost could be a significant portion of the overall product cost. Therefore, it is important to predict warranty cost accurately. However, most existing warranty cost models are not realistic in the sense that perfect or minimal repair is assumed. This paper presents four new warranty cost models which all assume imperfect repair. Imperfect repair restores the system operating state to somewhere between “as good as new” (perfect repair) and “as bad as old” (minimal repair), and could include two extreme cases: minimal and perfect repair. Thus, the warranty cost model with imperfect repair is more general and realistic. Warranty of a k-out-of-n system with imperfect maintenance is also studied in this paper. To gain advantages in highly competitive markets, manufacturers may have to enhance their warranty offerings. In warranty cost models B and D, preventive maintenance of unfailed components is considered. Model D considers a k-out-of-n system with opportunistic maintenance where partial failure is allowed. Under this kind of warranty policy, consumers not only receive free repairs upon premature failures, but also free preventive maintenance. This paper models imperfect repair using quasi-renewal processes introduced by Wang and Pham (1996). Model developments in this paper show that quasi-renewal processes are a convenient tool for warranty modeling with imperfect repair.

Improving performance and reliability of an IMS network by co-locating IMS servers

Abstract: The IP Multimedia Subsystem (IMS) is an architecture for supporting multimedia services via a Session Initiation Protocol (SIP) infrastructure. IMS, specified by the 3rd Generation Partnership Project (3GPP), is increasingly adopted as the reference multimedia network architecture by providers of wireline and wireless infrastructure and associated multimedia application services. One of the characteristics of the IMS architecture is that many different and mandatory SIP proxies are used for each end-to-end SIP session. This may adversely impact the overall IMS call processing performance, which is already affected by the universal usage of SIP. This also makes each end-to-end SIP session dependent on the good functioning of many hosts, which decreases reliability while increasing significantly the end-to-end message latency. This paper analyzes the performance and quantifies the benefits of having the SIP servers running on the same host. It then explains which types of SIP calls in the IMS network can benefit from the co-location of IMS servers and shows how to design the IMS network to maximize IMS server co-location. Finally, it introduces Lucent Technologies' SIPia BUS software architecture, which implements the co-location capability by introducing a new SIP transport in a way that is both natural and non-disruptive for the SIP stack and the SIP user agent.

Reliability growth and forecasting for critical hardware through accelerated life testing

Abstract: Lucent Technologies performs accelerated life testing (ALT) for critical hardware sub-assemblies used in telecommunication systems. Critical hardware includes power amplifiers, radio units, and other sub-assemblies that have a strong impact on system reliability. ALT is used to evaluate potential product weaknesses and performance degradation over a simulated operational lifetime. These weaknesses can be remedied through design changes prior to volume manufacturing and field deployment. ALT also provides statistical information that can forecast the steady-state product reliability under the expected field conditions, and measures progress towards satisfying field reliability requirements. Results indicate that a well-executed ALT program is an effective method to achieve reliability growth and forecast steady-state reliability. This paper reviews the ALT strategy, supporting models, product case studies, and program benefits. Case studies provide examples of design changes to achieve reliability growth, and demonstrate favorable comparison between the observed steady-state field reliability and the ALT predictions.

System aspects and handover management for IEEE 802.16e

Abstract: The IEEE 802.16 family of standards that are currently being developed target wide area, cellular, high data rate transmission for non-line-of-sight terminals. The initial phase of the standard (802.16d) supports fixed terminal locations and the subsequent phase of the standard (802.16e) provides support for mobile terminals. The standards specify physical layer (PHY) and media access control (MAC) layer functionalities with several flexible options for frequency reuse and handover. We describe various system architectures for handling handovers in an 802.16e system based on the capabilities of the current draft standard (802.16e D8). The system architecture description combines the functionalities provided in the standard at the PHY and MAC layers with network layer signaling to provide a complete solution. Specifically, we propose hard handover with MAC context reset for a low mobility scenario and a layered migration procedure using fast base station switching (FBSS) with MAC context transfer for a high-mobility scenario and Internet Protocol (IP) packet forwarding for seamless mobility. Our handover solution is applicable to both flat and centralized network architectures. We discuss evolution paths through these various options, keeping in mind that the initial deployments are likely to be for limited mobility and low capacity, while future deployments will target high mobility and increased capacity.

Eight ingredients of communications infrastructure: A systematic and comprehensive framework for enhancing network reliability and security

Abstract: Controlled improvement in the reliability and security of any system requires a comprehensive analysis. This requires the systematic identification of the fundamental underlying components of the system using a rigorous discipline. If successful, this process will illuminate areas for concern and identify areas for potential system enhancements. Such comprehensive analysis can be conducted for communications infrastructure using a framework of eight ingredients. This paper will explore these eight ingredients and identify their usage in vulnerability analysis and best practice identification for enhancing the reliability and security of communications infrastructure.

MapWeb: A location-based converged communications platform

Abstract: Location information is a valuable tool in personal communication systems, especially considering the wide variety of communication mechanisms that are available and affordable today. Users can easily access different types of networks (e.g., the public switched telephone network (PSTN), cellular networks and Internet Protocol (IP) networks), and they can choose to communicate via voice, data or video. An interesting issue is how we can blend location information, different communication services, and other advanced mechanisms such as policy control and presence information to build a visually oriented, easily personalized communication platform. We present MapWeb, a novel location-based platform that allows a user, via a map interface, to locate in her vicinity buddies and points of interest such as restaurants, hotels, banks, and gas stations, and to communicate with these entities via the communication mechanism of her choice. The system is built on the IP Multimedia Subsystem (IMS) architecture and is fully extensible at both the server and the client sides. It has many potential applications in settings such as security, emergency response, salvage, traffic management and Olympic-scale activity organization.

SIP message prioritization and its applications

Abstract: Session Initiation Protocol (SIP) signaling is an integral part of the IP Multimedia Subsystem (IMS) to support services such as Voice over IP (VoIP), multimedia sessions, presence, and instant messaging (IM). All of these services share a common SIP signaling infrastructure. In spite of careful network engineering, SIP network elements may experience high-load situations, in which SIP messages may experience too much delay or even get dropped. This paper addresses how such undesired high-load situations can be handled effectively by introducing a message prioritization mechanism in SIP servers. To validate the mechanism, it has been implemented in a high-performance JAIN∗-SIP-compliant Java∗ SIP stack. This SIP stack incorporates several other innovations, such as a very efficient SIP message parser, and it can be used for a variety of SIP-based applications. Its design enables service providers to define custom message prioritization and rejection strategies based on SIP message characteristics, system state, and statistics. Measurements show that high-priority emergency messages can indeed be serviced without significant delay or loss in a high-load situation. The concept of and techniques for SIP prioritization are the subjects of a Lucent Technologies patent application.

Optimal availability and security for IMS-based VoIP networks

Abstract: Consumers are continuously looking for ways of improving their productivity, simplifying their tasks, and streamlining communications both domestically and globally. This has resulted in the need to support different applications and thus the ongoing process of migrating many network services from traditional circuit-switched networks to Internet Protocol (IP) to converged networks. The circuit-switched public switched telephone network (PSTN) was a closed network where cyber-security threats were not a major issue. With the advent of converged networks and IP-based services, service providers, government, and enterprises are concerned about the growing security threat. The new networks and equipment will be subject to many types of threats and their vulnerabilities may expose mission critical applications and infrastructure to risk. Realization of these threats can lead to service outage. Today's communications service provider must decide how to treat the effects of security breaches so as to minimize service downtime. This paper highlights a methodology, with examples to identify the effect of security-related failures and the critical design factors to be considered when modeling service reliability. The ITU-TX.805 standard (now also ISO standard 18028-2), based on the Bell Labs security model, is used to evaluate potential high impact threats and vulnerabilities. The analysis uses the Bell Labs domain technique known as security domain evaluation. One of the critical outputs provides a prioritized understanding of the threats the network is exposed to and the vulnerabilities in the security architecture. The next step in the methodology includes incorporating the threats (vulnerabilities) identified in a reliability model and quantifying the corresponding service degradation. In this paper, these concepts are applied to IP Multimedia Subsystem (IMS)-based VoIP (Voice over IP) networks. Using reliability metrics, our analysis shows that reliability models are optimistic if we do not consider security. We demonstrate how reliability models can be enhanced to take security issues into account and that the X.805 standard can be used to identify the security threats. Finally, the model shows the mitigation in downtime by including intrusion-tolerance features in the product and network design. Consideration of security-caused downtime will lead to increased focus on preventing security vulnerabilities that can lead to service outages and also allow service providers to save on maintenance costs.

A novel software approach for service brokering in advanced service architectures

Abstract: Service brokering considerably enhances advanced service architectures, such as IP Multimedia Subsystem (IMS), since the myriad applications potentially involved in a call or other session are located in the application layer and are separate and large grained. Through effective service brokering — that is, the effective blending and coordinating of services — interaction problems can be controlled and new composite services offering an enriched end-user experience can be provided. How can an effective service brokering capability be realized in a product when it must address needs not yet known? This question instigated the novel software approach (covered by filed Lucent patents) used in the Lucent Service Broker™ product. Adapting techniques used in Web servers and Session Initiation Protocol (SIP) servlet engines, but bringing to the design the special needs for service interaction and blending along with attendant needs for scalability and performance, the Lucent Service Broker was designed as a software engine with a powerful but easy-to-use API for customer programmability. This paper describes the software design of the Lucent Service Broker, particularly focusing on its novel aspects.

Subscriber data management in IMS networks

Abstract: Next-generation communication services will be driven by increasingly rich and distributed subscriber information. Current wireless networks have evolved such that subscriber information now resides in various elements e.g., home location register [HLR], prepay, voice mail, short message, and location determination systems). Convergence with the Internet promises significantly more personal information, such as presence, calendars, address books, buddy lists, pictures, and video. The home subscriber server (HSS) in the IP Multimedia Subsystem (IMS) architecture provides centralized storage for subscriber data. However, some application servers will also have their own subscriber data. As the quantity and variety of applications grow, it will become increasingly useful to provide unified views of subscriber data both within a network and across networks. The Lucent Datagrid™ software provides a telecom-targeted data integration capability, so that applications can use a logical “single-point-of-access” for user profile information inside a service provider's network.

The rollout of optical networking: LambdaXtreme® national network deployment

Abstract: The LambdaXtreme® Transport System was designed to enable all-optical transmission for unprecedented distances, without regeneration and with ultra-high capacity. In this paper, we provide a detailed view into what was done before, during, and after a nationwide deployment to ensure that the network builds would be completed on time and perform as designed.

IMS security

Abstract: The IP Multimedia Subsystem (IMS) provides a powerful session and service architecture creating a platform for next-generation user services. In order to enable these services, a security approach and architecture is required to address the vulnerabilities inherent to Internet Protocol (IP)-based solutions. The security architecture is driven by 3rd Generation Partnership Project (3GPP) and 3rd Generation Partnership Project 2 (3GPP2) security standards along with the security model described in International Telecommunications Union (ITU) Recommendation X.805, “Security Architecture for Systems Providing End-to-End Communications.” This paper examines threats and vulnerabilities of IMS implementations as well as high-level service provider security requirements, and defines an implementation approach to provide the desired level of security for IMS deployments.

Optical technologies and techniques for high bit rate fiber transmission

Abstract: The last few years have witnessed rapid advances in optical technologies and techniques for high-speed fiber transmission that have resulted in record-setting capacity-distance products and highly flexible and transparent optical networking. In this paper, we review some of the new key enabling approaches used in optical terminals, repeaters, and link designs. In particular, we summarize advances in modulation formats and their corresponding transmitter and receiver designs, broadband Raman amplification, chromatic dispersion compensation, polarization mode dispersion mitigation, and hybrid 10 Gb/s and 40 Gb/s dense wavelength division multiplexing (DWDM).

MAGNET: An approach for secure personal networking in beyond 3G wireless networks

Abstract: The paper presents the major concepts for a next-generation personal network as defined, developed, and tested by the project My Personal Adaptive Global NET (MAGNET), including the growing personal area network (PAN) style networking. The MAGNET vision is that personal networks (PNs) will support users' professional and private activities without being obtrusive and while safeguarding their privacy and security. A PN can operate on top of any number of existing networks or may be composed in an ad hoc, self-organized manner. PNs are dynamic and diverse in composition, configuration, and connectivity depending on time, place, preference, and context as well as resources available and required, and they function in cooperation with all necessary/required and preferred partners. This paper focuses on specific aspects related to PNs such as advances in peer-to-peer networking and interworking with infrastructure-based networks (e.g., dynamic personal virtual private networks) and security requirements and solutions for secure personal networking.

Modeling planned downtime

Abstract: In general, service providers have only placed system availability requirements on equipment providers for unplanned system downtime. However, reliability expectations of service providers are shifting in a manner that places requirements on equipment providers to manage all system downtime (i.e., planned system downtime as well as unplanned system downtime) rather than focusing solely on guaranteeing unplanned system downtime. Furthermore, service providers continuously request improvements in total system availability (e.g., requiring 99.999% system availability, which translates to 5.25 minutes of total system downtime per year). While numerous models exist for modeling unplanned system downtime, there are no equivalent models for planned downtime. This paper presents a planned downtime event taxonomy, characterizes the planned downtime for each category in the taxonomy, and incorporates the results into a model for predicting the total planned downtime associated with a system. It then uses the model on an example system, demonstrating the capability of the model in assessing various system design alternatives.

An introduction to Lucent's service enhancement layer

Abstract: The 3rd Generation Partnership Project (3GPP) IP Multimedia Subsystem (IMS) standards provide a core telecommunications network architecture that promises high flexibility in the creation of new and blended services. This stems primarily from two aspects: access independence and the highly flexible, extensible Session Initiation Protocol (SIP). Lucent Technologies' Service Enhancement Layer provides a suite of standards-compliant tools and technologies that can work in and above the IMS core, allowing service providers to realize the full potential of IMS in a cost-effective manner. These enablers are, at a fundamental level, carrier-grade middleware that can reside on the most appropriate hardware platform. The three most important components of this layer are the Lucent Service Broker™ application, which enables blending of IMS services without having to modify the application servers; the Unified Subscriber Data Server, which provides a comprehensive approach to managing subscriber profile data regardless of where it is sourced; and the Lucent Vortex™ policy management infrastructure, which provides a high-speed rules engine suitable for personalization and flexible network optimizations. This layer, which also includes other components such as the presence server, can grow to include additional components. The Active PhoneBook application, which includes both server-side and client-side components, is useful as a hub for providing blended services to end users.

Service capability interaction management in IMS using the Lucent Service Broker™ product

Abstract: The 3rd Generation Partnership Project/3rd Generation Partnership Project 2 (3GPP/3GPP2) designates the service capability interaction manager (SCIM) as a functional component in the IP Multimedia Subsystem (IMS). This paper focuses on how the Lucent Service Broker™ product has been designed and how it would be deployed to perform as a SCIM in an IMS network. We discuss the challenges in managing service capability interaction and providing blended services that are encountered in IMS and show how Lucent Service Broker flexibility is needed to accommodate the breadth of challenges. We describe how the internal structure of the Lucent Service Broker and its application programming interface (API) offer this flexibility while minimizing the effort involved in adding new SCIM logic. We also demonstrate how the Lucent Service Broker may be used to marshal IMS application resources on behalf of revenue-generating applications in various usage scenarios.

Seamless mobility across IMS and legacy circuit networks

Abstract: The growing desire of network providers to introduce support for voice over IP (VoIP) has created interesting challenges in the area of interoperability with existing wireless circuit networks. The 3rd Generation Partnership Project (3GPP) and the 3rd Generation Partnership Project 2 (3GPP2) standards have defined the IP Multimedia Subsystem (IMS) as the platform for convergence. By definition, IMS is access agnostic; it provides services and features through a common core network, regardless of the means of transport. However, the IMS standards are just beginning to address the challenges associated with interworking with existing cellular circuit networks. Achieving seamless mobility involves supporting both roaming and handoff between networks. This paper discusses the issues involved in providing seamless mobility for subscribers across the packet and circuit domains and proposes network-based solutions.

Integrating optical transport quality, availability, and cost through reliability-based optical network design

Abstract: The design of the optical transport network (OTN) must meet the challenges of providing a high capacity, highly dependable and reliable network and the flexibility in bandwidth management to support multi-services in a cost-effective manner. The core objective of the OTN design activity focuses on carefully balancing these design objectives. This paper presents a comprehensive design approach that integrates the OTN design with its end-to-end reliability assessment. Quantitative reliability assessment becomes an integral part of the OTN design process when considering network survivability using various protection and restoration schemes. This value-based reliability approach provides a complete set of network reliability profiles. These profiles provide a means to: 1) drive network architecture and infrastructure design by identifying both strong and vulnerable region(s); 2) provide reliability/availability cost and worth (benefit) tradeoff by quantifying the impact of various network elements and/or protection schemes; and 3) allow design of reliability-based revenue offers or service level agreements (SLAs). We will illustrate the application and benefits of using OTN reliability-based design processes in several service provider networks featuring synchronous optical network/synchronous digital hierarchy (SONET/SDH) ring and dense wavelength division multiplexing (DWDM) mesh architectures including dedicated and shared protection/restoration schemes in backbones and in metropolitan networks.

IMS service-based bearer control

Abstract: With the blurring of the lines between traditional telephony services and the growing number of Internet Protocol (IP)-based services available to customers of voice- and data-service providers, there is a growing need to provide a vertical interface between the service/session layer (where the service intelligence exists) and the transport layer (which provides the bearer path for service data traffic). The communication between the service/session layer and the bearer plane is referred to in standards organizations and in this paper as service-based bearer control (SBBC). The 3rd Generation Partnership Project (3GPP), the 3rd Generation Partnership Project 2 (3GPP2), the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Focus Group on Next Generation Networks, and other standards organizations are discussing interfaces to provide SBBC functionality. This paper addresses the requirements of the SBBC interfaces and provides information about the capabilities they provide, but it does not reflect any particular set of standards, because the standards in this area are still very much under development. Rather, it presents various issues that are being discussed and that will influence the standards that are ultimately agreed upon.

Mobile Application security system (MASS)

Abstract: Security is an important factor in any network, but particularly in a wireless ad-hoc network in which mobile applications are employed to perform various tasks. By mobile applications, we mean applications that can support both moving nodes (e.g., transmitter/receiver mounted on a moving vehicle) and migrating code (i.e., code that can transport itself via wireless link from one execution node to another). These networks remain more vulnerable to compromise by malicious applications and hosts due to their innate characteristic of no clear line of defense. We devised a potential solution to this problem that addresses critical aspects of security in ad-hoc mobile application networks. This approach involves preventing unauthorized modification of a mobile application, both by other applications and by hosts, and ensuring that mobile code is authentic and authorized. These capabilities constitute the Mobile Application security system (mass). The MASS applies effective, robust security to mobile application-based systems, wireless, and wired networks while minimizing overhead requirements. The MASS consists of innovative security techniques that provide distributed security solutions for mobile application networks.

Piecewise analysis and modeling of circuit pack temperature cycling data

Abstract: Temperature cycling environmental stress testing (EST) of circuit packs is a standard test procedure for the precipitation of latent defects in order to minimize early product lifecycle customer returns. EST is an expensive, energy-intensive bottleneck in the manufacturing process, one that is based on empiricisms that may be out of date. This presents great opportunity for optimization and test cost reduction. This paper describes the characterization of temperature cycling through analysis and modeling of process data in order to optimize the test parameters — ramp rate, temperature extremes, dwell times, and number of cycles. Failure data from circuit packs tested at a Lucent facility is analyzed using a regression technique and graphical inspection. The dwell and ramp periods of the test are considered in a piecewise manner. A cost model is applied based on distributions fitted to the failure data. The analysis yields a methodology for the dynamic, value-based optimization of temperature cycling EST.

Semantic reliability of multi-agent intelligent systems

Abstract: Generally the concept of reliability has been interpreted as applied to hardware and software and has been based upon the assumption that a system can be decomposed into subsystems or components to which success or failure probabilities can be assigned assuming perfect semantic transactions between them, i.e., with no consideration to variation in the interpretation of the meanings of messages between various components. In multi-agent intelligent systems, where the agents interact with each other in capacities other than merely sending and receiving messages, cooperative decisions are made based upon beliefs, desires, intentions, and the autonomy of individual agents. In such cases, even if the components as well as the interconnections are error-free in the classical sense, there can be serious failures due to semantic variability and consequently the concept of reliability needs to be extended to semantics as well. This paper attempts to establish this new concept of semantic reliability and explore its relationship to the system reliability and information extraction processes. Here we examine the communication between agents and semantic error modes in multi-agent systems using Rao and Georgeff's belief-desire-intention (BDI) model of intelligent agents to decompose the semantic variation into its contributing parts from various subsystems comprising the agents. From this, the impact and the risk management strategies including fault tolerance are evolved. World representation, domain ontologies, and knowledge representation are brought out as important determinants of error control. A fault tolerance design based on goal hierarchy is suggested.

Reliability in Ethernet networks: A survey of various approaches

Abstract: Services based on Ethernet are fast becoming favorites of service providers because of the availability of higher bandwidth at lower cost. However, as more and more equipment is being installed in the networks, network reliability and performance are becoming the most critical attributes named by the service providers. In the absence of one standard that fits all Ethernet reliability needs, the Ethernet equipment vendors are coming up with a number of varied solutions to meet their immediate needs. This paper discusses various approaches that have been suggested or implemented in Ethernet equipment and network design. It highlights the pros and cons of these approaches and suggests which approach fits best for a particular network and scenario. The paper also discusses the reliability approach considered for point-to-point Ethernet services as well as for networks providing Ethernet interworking with Asynchronous Transfer Mode (ATM), Frame Relay, and Multiprotocol Label Switching (MPLS).