Modeling of the XOM/XMP application programming interface (API)

With the growing complexity of communication protocols, it is increasingly difficult for application developers to interface the applications to the communication stacks across a number of platforms. A common application program interface (API) is needed for the purpose. The API can effectively conceal the complexities of communication protocols and architecture, making it easier for application development. This article presents the modeling and development of a generic API, XOM and an application-specific API, XMP. XOM API provides a general-purpose data handling mechanism and XMP API provides service primitives to network management protocols. The development is based on object-oriented technology. The attractiveness of object-oriented implementation is its ability to provide encapsulation, reusability and extensibility in the software modules. The benefits and difficulties encountered during the implementation are to be discussed. The experience will be useful for API development     

Beyond IN and UPT-a personal communications support system based onTMN concepts

The vision for future telecommunications is often described by the slogan “information at any time, at any place, in any form”, driven by both society's increasing demand for “universal connectivity” and the technological progress in the area of mobile computing and personal communications. In order to realize this vision, the emerging concept of personal communications support (PCS), which includes support for personal mobility, service personalization, and advanced service interoperability, is becoming increasingly important since it allows users to configure their communications environment in accordance with their individual needs, thereby providing them with controlled access to telecommunication services, regardless of their current location, terminal and network capabilities. This paper provides an overview of a personal communications support system (PCSS). The PCSS represents a platform providing advanced PCS capabilities in a uniform way to numerous communication applications in distributed multimedia environments. From a functional perspective, the PCSS provides enhanced intelligent network (IN) and universal personal telecommunication (UPT) capabilities with respect to user addressing (based on logical names instead of numbers) and advanced user control capabilities. From a design perspective, the centralistic IN/UPT approach to the realization of service logic has been replaced by a highly distributable, object-oriented approach based on X.500/X.700/telecommunications management network (TMN) concepts. This paper addresses the basic aspects of the PCSS, including design criteria, system architecture, supported applications, and evolution issues     

TOPS: an architecture for telephony over packet networks

Packet telephony is of increasing interest in both the telecommunications and Internet communities. The emergence of packet telephony will create new services, and presents an opportunity to rethink how conventional telephony services are implemented. In this paper, we present an architecture for telephony over packet networks (TOPS). TOPS allows users to move between terminals or to use mobile terminals while being reachable by the same name. TOPS users can have multiple terminals and control how calls are routed to them. TOPS allows for terminals with a range of capabilities such as support for video, whiteboard, and other media with a variety of coding formats. TOPS retains the necessary information on terminal capabilities to determine the appropriate type of communication to be established with the remote terminal. The architecture assumes that the underlying network supports the establishment of end-to-end connectivity between terminals, with an appropriate quality of service. The components of TOPS are a directory service, an application layer signaling protocol, and a logical channel abstraction for communication between end-systems. The directory service maps a user's name to a set of terminals where the user may be reached. A user can control the translation operation by specifying profiles that customize how his name is mapped to a set of terminals where he can be reached. Terminal capabilities are also stored in the directory service. The application layer signaling protocol establishes and maintains call state between communicating terminals. The logical channel abstraction provides a shared end-to-end context for a call's constituent media and control streams, while isolating the applications from the details of the network transport mechanisms. In addition to supporting simple point-to-point calls, the architecture supports both centralized and decentralized conferencing. We also introduce a simple encapsulation format for voice     

Performance of Transport Protocols for Multimedia Communications in Wireless Sensor Networks

Many wireless sensor network (WSN) applications require efficient multimedia communication capabilities. However, the existing communication protocols in the literature mainly aim to achieve energy efficiency and reliability objectives and do not address multimedia communication challenges in WSN. In this paper, comprehensive performance evaluation of the existing transport protocols is performed for multimedia communication in WSN. Performance metrics such as packet delivery rate, end-to-end packet delay, bandwidth and energy efficiency, frame peak signal-to-noise ratio (PSNR), delay-bounded frame PSNR, frame delivery probability, frame end-to-end delay and jitter are investigated. The results clearly show that the existing transport protocols are far from satisfying the requirements of multimedia communication in WSN and hence there is a need for new effective multimedia delivery protocols for WSN.     

An architecture for real-time multimedia communication systems

A multimedia communication system includes both the communication protocols used to transport the real-time data and the distributed computing system (DCS) within which any applications using the protocols must execute. The architecture presented attempts to integrate these communications protocols with the DCS in a smooth fashion in order to ease the writing of multimedia applications. Two issues are identified as being essential to the success of this integration: the synchronization of related real-time data streams, and the management of heterogeneous multimedia hardware. The synchronization problem is tackled by defining explicit synchronization properties at the presentation level and by providing control and synchronization operations within the DCS which operate in terms of these properties. The heterogeneity problems are addressed by separating the data transport semantics (protocols themselves) from the control semantics (protocol interfaces)     

EuroBridge: communications services for multimedia applications

The aim of the EuroBridge project is to provide a uniform communication service platform. This platform will provide true multimedia multipoint services including interactive video conferencing and store-and-forward data services. The project will enhance selected OSI application layer services to provide them with multimedia capabilities. Selection of the initial services as well as the identification of necessary functional enhancements were based on actual user requirements. To support the dedicated communication requirements imposed by multimedia and multipoint applications, the lower layers of the OSI model will be enhanced accordingly. This includes designing and implementing new lightweight session and presentation protocols, respectively. Furthermore, high-speed transport protocols will be utilised. The actual protocol stack used will be configured dynamically depending on the requested quality of service. Support of multicast capabilities will be a crucial issue. The service platform is being implemented to run on top of different high-speed networks, including FDDI and DQDB     

A flexible middleware for multimedia communication: design,implementation, and experience

Distributed multimedia applications require a variety of communication services. These services and different application requirements have to be provided and supported within: (1) end-systems in an efficient and integrated manner, combining the precise specification of quality-of-service (QoS) requirements, application interfaces, multicast support, and security features and (2) the network. The Da CaPo++ system presented in this paper provides an efficient end-system middleware for multimedia applications, capable of handling various types of applications in a modular fashion. Application needs and communication demands are specified by values in terms of QoS attributes and functional properties, such as encryption requirements or multicast support. Da CaPo++ automatically configures suitable communication protocols, provides for an efficient runtime support, and offers an easy-to-use, object-oriented application programming interface. While its applicability to real-life applications was shown by prototype implementations, performance evaluations have been carried out yielding practical experiences and numerical results     

The (R)evolution of access networks for the informationsuperhighway

Competition in deregulated telecommunication markets forces network operators to modernize their access networks-often called the “last mile” to the customer-to provide a mix of multimedia and traditional telecommunication services. Economics necessitate an evolutionary, step-by-step approach to migrate from the present access infrastructure-composed mainly of existing telephone networks and cable TV networks-to the ultimate information superhighway. At the end of the day, however, networks of different operators should provide interconnectivity for the same set of services. A system concept is described that drives access network technology toward a “common platform” with generic access methods, cognate routing and switching, and common, standardized communication protocols. Simulation results show some performance figures of the common platform concept. An implementation on a CATV network is presented as well     

Wireless ATM networks: technology status and future directions

The concept of “wireless ATM” (WATM), first proposed in 1992, is now being actively considered as a potential framework for new-generation wireless communication networks capable of supporting integrated, quality-of service (QoS) based multimedia services. In this review paper, we outline the technological rationale for wireless ATM, present a system-level architecture, and discuss key design issues for both mobile ATM switching infrastructure and radio access subsystems. The WATM radio access layer issues covered in this paper include: spectrum allocation; spectrum etiquette; modem technology; and medium access/data link control (MAC/DLC) protocols. Mobile ATM aspects such as ATM signaling extensions for handoff control, location management, and mobile QoS control are discussed. A summary of current wireless/mobile ATM technology development and standardization status is given, including an outline of our WATMnet prototype. The paper concludes with a discussion of future directions for wireless ATM technology such as Internet protocol (IP) integration and mobile multimedia terminals/applications     

多媒体数据库管理系统

多媒体数据库管理系统是针对多媒体数据的有效管理而提出的一个数据库管理系统,跟一些传统的数据库管理系统相比,多媒体数据不同于传统数据,是一种非格式化数据,具有对象复杂、存储分散及时空同步等特点。为方便管理,本系统采用面向对象方法进行设计与开发。通过引入封装、继承、对象和类等概念,可以有效地描述各种对象及其内部结构与联系,提高对非格式化多媒体数据的管理能力。     

A programmable transport architecture with QoS guarantees

The emergence of distributed multimedia applications exhibiting significantly more stringent quality of service requirements than conventional data-oriented applications calls for new transport protocols with different characteristics to coexist and be integrated within single applications. The different delivery requirements posed by these diverse multimedia applications often imply the need for highly customized protocol implementations. Hence, application developers are faced with the threat of code obsolescence caused by the development of even newer delivery techniques. We present an object-oriented transport architecture that allows for dynamically binding a variety of protocol stacks on a per-call basis. By binding protocol stacks together, the special needs of the application can be met without the need to rewrite the code. This differs significantly from the traditional transport architecture which assumes preinstalled transport protocol stacks that cannot be customized. To illustrate some of the advantages provided by the architecture, we describe the transport component of the first reference implementation of the 150 MPEG-4 Delivery Multimedia Integration Framework and demonstrate how quickly it was implemented in our framework     

WATMnet: a prototype wireless ATM system for multimedia personalcommunication

A prototype microcellular wireless asynchronous transfer mode network (WATMnet) capable of providing integrated multimedia communication services to mobile terminals is described in this paper. The experimental system's hardware consists of laptop computers (NEC Versa-M) with WATMnet interface cards, multiple VME/i960 processor-based WATMnet base stations, and a mobility-enhanced local-area ATM switch. The prototype wireless network interface cards operate at peak bit-rates up to 8 Mb/s, using low-power 2.4 GHz industrial, scientific, and medical (ISM)-band modems. Wireless network protocols at the portable terminal and base station interfaces support available bit rate (ABR), variable bit rate (VBR), and constant bit rate (CBR) transport services compatible with ATM using a dynamic time-division multiple-access/time-division duplex (TDMA/TDD) MAC protocol for channel sharing and data link control (DLC) protocol for error recovery. A custom wireless control protocol is also implemented between the portable and base units for support of radio link related functions such as user registration and handoff. All network entities including the portable, base and switch use a mobility-enhanced version of ATM (“Q.2931+”) signaling for switched virtual circuit (SVC) connection control functions, including handoff. In the first stage of the prototype, the application-level API is TCP/UP over ATM ABR service class using AAL5. Early experiments with the WATMnet prototype have been conducted to validate major protocol and software aspects, including DLC, wireless control, and mobility signaling for handoff, Selected network-based multimedia/video applications requiring moderate bit-rates (~0.5-1 Mb/s) in the ABR mode have been successfully demonstrated on the laptop PC     

Multimedia via Inmarsat

Inmarsat's provision of multimedia services over its current satellites, as well as over a possible new generation of satellites, will enable technologies for support of higher data rates for mobile terminals. Inmarsat's next-generation satellite communications system will extend current capabilities by supporting fully interactive multimedia communications to small portable user terminals     

User-controlled, multimedia-enhanced communication using prior knowledge and experience

This article focuses on enriching the communication experience between human beings interacting through different kinds of devices, including mobile phones and PDAs. The key point is how to effectively exploit multimedia data to enhance the richness of communication without overloading the communication channel. To this end, the system tries to minimize the quantity of information transmitted over the networks and to maximize the usage of locally stored information. The proposed system sends several kinds of data, including continuous video, video clips, still images, and avatars, over the communication channel. The specific data that are sent are based on the parameters set by the transmitting and receiving terminals. Bandwidth-consuming data, such as continuous video, are transmitted only occasionally at the receiving terminal. The system has been partially implemented and incorporated in avatar-enabled cellular phones. The user may then easily create different avatars combining components characterizing faces, hair, and so on, and associate them with different callers. When a call comes through, the avatar corresponding to the caller is retrieved and displayed on the screen and the corresponding information is retrieved from the personal database.     

一种包含异常处理结构的面向对象切片方法

针对面向对象语言的特点,结合异常处理机制,对传统的系统依赖图（SDG图）进行了扩展,实现了面向对象的系统依赖图（OSDG图）.改进后的OSDG图可以很好地支持继承和多态等特征,并能处理多态对象抛出和处理异常所带来的数据和控制依赖关系.通过传统的程序切片算法,可以在OSDG上切出较为精确的切片.     

Processing the new world of interactive media

Trimedia is a family of programmable multimedia processors from the Trimedia product group of Philips Semiconductors. This architecture is based upon a high-performances VLIW CPU core. TM-1000 is the first product from a family of multimedia processors based upon the Trimedia architecture. TM-1000 is designed to concurrently process video, audio, graphics, and communication data. TM-1000 consists of a high-performance VLIW-based CPU core, large instruction and data caches, main memory interface, and video, audio and communication related peripherals. TM-1000 is a multimedia system on a chip: high-quality video and audio applications can be implemented in TM-1000 using high-level languages such as “C” and “C++”. The authors mainly focus on the VLIW CPU architecture     

Object-oriented analysis of signalling and control in broadband networks

This paper analyses the problem of providing call, connection, channel, and service control in broadband and intelligent networks to support a wide variety of services. A formal methodology called object-oriented analysis (OOA) is used to analyse this problem. Three types of OOA models are constructed: the information model, state models and the object communication model. From these models, a distributed call processing architecture that proposes separate servers for call control, connection control, channel control and service control, is derived. Based on the events used for inter-object communication in the object communication model, service-specific and control-function specific application service elements are defined as client-server based protocols.     

Delay-sensitive and multimedia communication in cognitive radio sensor networks

Multimedia and delay-sensitive data applications in cognitive radio sensor networks (CRSN) require efficient real-time communication and dynamic spectrum access (DSA) capabilities. This requirement poses emerging problems to be addressed in inherently resource-constrained sensor networks, and needs investigation of CRSN challenges with real-time communication requirements. In this paper, the main design challenges and principles for multimedia and delay-sensitive data transport in CRSN are introduced. The existing transport protocols and algorithms devised for cognitive radio ad hoc networks and wireless sensor networks (WSN) are explored from the perspective of CRSN paradigm. Specifically, the challenges for real-time transport in CRSN are investigated in different spectrum environments of smart grid, e.g., 500 kV substation, main power room and underground network transformer vaults. Open research issues for the realization of energy-efficient and real-time transport in CRSN are also presented. Overall, the performance evaluations provide valuable insights about real-time transport in CRSN and guide design decisions and trade-offs for CRSN applications in smart electric power grid.     

Content and Service Protection for the Ubiquitous TV Based on Network Convergence

Today, the ubiquitous multimedia services are becoming more and more popular. However, the secure solutions that confirm the content and service security in these services are still open issues because of various network convergences and device interconnections. This paper investigates an ubiquitous multimedia service architecture and proposes a secure solution for it. In this service architecture, the multimedia content is encoded with scalable video coding and broadcasted via digital video broadcasting for handheld terminals (DVB-H) to mobile terminals, the access right is transmitted by global system for mobile (GSM/GPRS) channel, and the media content and access right can also be transferred from mobile terminals to home TV through WiFi based Wireless Local Area Network. The proposed secure solution supports three kinds of business models by using various content encryption modes and secure transmission protocols. The solution’s security is evaluated and discussed. Since few work has been done to solve this problem, the work proposed in this paper is expected to attract more researchers. Additionally, the solution is also potential for other ubiquitous services.