Distributed Broker-Agent Architecture for Multimedia Communications Traversing NAT/Firewall in NGN

The forthcoming Next Generation Network (NGN) is an all IP network. Multimedia communications over IP networks are a type of bundled session communications, which cannot directly traverse Network Address Translations (NATs) and firewalls even in NGN. To solve the problem that the existing traversal methods are not suitable for service providers to set up a real system in NGN, a Distributed Broker-agent Architecture (DBA) is addressed. DBA is secure and realizable for service providers and enterprises because it is easy to set up and does not need to upgrade the existing devices like Firewalls, NATs or endpoint devices of subscribers. DBA is composed of two-layer distributed agents, the server proxies and the client agents, in which all multimedia communications use shared tunnels to carry signaling messages and media data between broker-agents, and the call signaling is encrypted over Security Socket Layer (SSL) to guarantee the security of calling. Moreover, the function model and multiplexed connection messages format of DBA are designed, which lays a basis for the protocol in the future NGN. In addition, a simple implementation based on H.323 verifyies the main function of traversing firewalls and NATs.

High－Performance Network Communications for CSCW

Computer supported cooperative work as a new multi disciplinary research area, brings a lot of new challenges for the computer technologies. Having analyzed the CSCW applications by using the groupware space time matrix, we conclude that the communicatio

Performance of joint dual links dynamic power control and smart antenna for TDMA/TDD cellular mobile communications

Interference cancellation is made available by using smart antenna at cellular base stations. Well distributed cumulative probability of signal to interference plus noise power ratio appears to be vital for cellular mobile multimedia communications. A scenario of dual links dynamic power control combined to a solution of smart antenna is proposed to adjust the instant transmission power in terms of the disparity from the favorite range. Simulation results show that this method is quite effective to improve the cumulative distribution probability performance. Meanwhile, accompanying low power consumption is also obtained at both base stations and mobile stations.

A Recovery Algorithm for Self-Stabilizing Communication Protocols

This paper presents a recovery algorithm for self-stabilizing communication protocols. It first describes some concepts and a formal description method for the algorithm. Then it proposes the algorithm procedures, proves its correctness and analyses its complexity. Finally, it also verifies the availability and efficiency of the algorithm by illustrating an example protocol with multi-processes.

A Signaling Protocol Supporting Multimedia Services

A flexible and extendible control mechanism for invoking services is required for taking full advantage of the potential B--ISDN services. In this paper, a flexible specification of signaling protocol based on an object-oriented call mode is proposed. The article’focuses on the protocol’s message syntax, message flow model, and applicability for defining multimedia and multiparty services.’

The Algorithms for Achieving Global States and Self-Stabilization for Communication Protocols

This paper discusses the algorithms for achieving global states and self-stabilizationfor communication protocols. It first describes a primary algorithm including its suitability forachieving global states and limitation of self-stabilization for communication protocols, and thenpresents an improved algorithm that can be suitable to achieve global states and can be also usedto self-stabilizing communication protocols. Filially, it gives the proof of correctness and analysis ofcomplexity of the improved algorithm, and verifies its availability and efficiency by illustrating anexample protocol.

Study on Multimedia Visual Design of Intangible Cultural Heritage in Lingnan

This study analyzes and gives advice on the relevant folk culture of Lingnan from the perspective of digital protection and inheritance, through the implementation of multimedia interaction scenarios and interaction processes, the historical and cultural implications of the Lingnan heritage, the stories of local folklore and the simulation interaction of the production process are realized. This paper proposes a visual and realistic concept of Lingnan culture, and uses the multimedia design method of image animation, audio and other multimedia design methods to sense the virtual reality design, aiming at the historical background, folk culture, craft culture, business culture and so on. The core is vividly communicated to the public. Bringing the Lingnan people a more immersive and authentic cultural experience.

Fairness based channel borrowing strategy in multimedia LEO satellite communications

A novel bandwidth allocation strategy along with a connection admission control technique was proposed to improve the utilization of network resources.It provides the network with better quality-of-service(QoS)guarantees,such as new call blocking probability(CBP)and handoff call drop-ping probability(CDP)in multimedia low earth orbit(LEO)satellite networks.Simulation results show that,compared with other bandwidth allocation schemes,the proposed scheme offers very low call dropping probability for real-time connections while,at the same time,keeping resource utilization high.Finally we discussed the fairness for the borrowed nonreal-time connections under three different channel borrowing methods.

多媒体辅助教学在《传染病护理学》教学中的应用

目的：研究《传染病护理学》教学的最佳方法。方法：对采用多媒体和传统教学两种不同授课方法的实验组和对照组学生的问卷调查及考试成绩比较分析。结果：实验组和对照组学生的问卷调查及成绩比较,差异有显著性(P＜0.05)。结论：在《传染病护理学》教学中应用多媒体辅助教学,可优化教与学之间的传输和反馈；解决临床病例资源不足或匮乏等难题；建立了理论与实际相联系的桥梁和提高教学质量。

计算机媒介传播与英语教学(英文)

本文探讨多媒体与互联网在英语教学中的两种综合运用模式，分析由此产生的关于计算机辅助语言教学的核心问题，阐述计算机媒介传播为媒体与网络的综合功能和运用趋势。

A PERFORMANCE EVALUATION INDEX SYSTEM FOR MULTIMEDIA COMMUNICATION NETWORKS AND FORECASTING FOR WEB-BASED NETWORK TRAFFIC

This paper presents a new index system for the performance evaluation and network planning of multimedia communication systems using measurement on actual systems to support several different traffic types. In this index system, we develop an expert system to evaluate the performance of such multimedia communication networks including channel utilization and call blocking probability and packet delay, and apply the network planning methods to optimize the networks and forecast the demand of the growing multimedia communications systems. Two important planning problems for the multimedia communication systems are presented: optimization problem for construction of the world system and forecast problem for increasing traffic demands. We first discuss analysis methods, performance measures for the multimedia communication systems. Then, we describe network planning methods for the multimedia communication systems and give some efficiency network planning methods. Finally, we present some results studied in traffic forecast for the campus network and show the effectiveness of these methods.

Ant Colony Optimization for Multi-Objective Multicast Routing

In the distributed networks,many applications send information from a source node to multiple destination nodes.To support these applications requirements,the paper presents a multi-objective algorithm based on ant colonies to construct a multicast tree for data transmission in a computer network.The proposed algorithm simultaneously optimizes total weight(cost,delay and hop)of the multicast tree.Experimental results prove the proposed algorithm outperforms a recently published Multi-objective Multicast Algorithm specially designed for solving the multicast routing problem.Also,it is able to find a better solution with fast convergence speed and high reliability.

Abstract of ph.d Dissertation

With the rapid development of global information highway,multimedia communication technology plays a more and more important role in national economic and social development.However,the multimedia communication system is a complicated real time distributed system and its software is difficult to develop.In order to improve the rapid development and application of the multimedia communication technology,there is an urgent need to carry out the basic research work of software development platform in this field.……

A Bandwidth Control Method Providing Entrance QoS for Multimedia Communication

With the development of wideband IP network, many new IP-Based multimedia applications appear ceaselessly. The real-time multimedia application requires that the IP network provides QoS. To the end-to-end real-time multimedia communication, the QoS service includes the trunk QoS and the entrance QoS. The trunk QoS has some feasible technologies, such as RSVP and DiffServ. But, the entrance QoS has few technologies at the moment. So, this paper introduces the entrance bandwidth control to get the end-to-end QoS. The design and scheme of bandwidth controller applying to the usual Internet application and real-time media communication is provided in this paper. It distinguishes between the usual 1nternet applications, such as HTTP and FTP, and the real-time multimedia applications, such as Internet telephony and videoconferencing. Then they will be dealt with in different ways in order to satisfy the QoS requirements of different types of services. In this paper, we propose a new bandwidth control method for real-time multimedia communication. The principle, the implementing flow, the control policy and the application scheme are discussed.

Self Fault-Tolerance of Protocols: A Case Study

The prerequisite for the existing protocols' correctness is that protocols can be normally operated under the normal conditions, rather than dealing with abnormal conditions. In other words, protocols with the fault-tolerance can not be provided when some fault occurs. This paper discusses the self fault-tolerance of protocols. It describes some concepts and methods for achieving self fault-tolerance of protocols. Meanwhile, it provides a case study, investigates a typical protocol that does not satisfy the self fault-tolerance, and gives a new redesign version of this existing protocol using the proposed approach.

Studies on Algorithms for Self-StabilizingCommunication Protocols

in this paper the algorithms for self-stabilizing communication protocols are studied. First some concepts and a formal method for describing theproposed algorithms are described, then an improved algorithm for achieving globalstates is presented. The study shows that the improved algorithm can be appliedto obtain the global states in the case of a loss of cooperation of the different processes in the protocol, which can be used as a recovery point that will be used bythe following recovery procedure. Thus, the improved algorithm can be used toself-stabilize a communication protocol. Meanwhile, a recovery algorithm for selfstabilizing communication protocols is presented. After a failure is detected, allProcesses can eventually know the error. The recovery algorithm uses the contextualinformation exchanged during the progress of the protocol and recorded on the stablememory. The proof of correctness and analysis of complexity for these algorithmshave been made. The availability and efficiency of the algorithms have been verifiedby illustrating the example protocols. Finally, some conclusions and remarks aregiven.

Convergence of Broadband and Broadcast/Multicast in Maritime Information Networks

Recently,the fifth-generation(5G)of wireless networks mainly focuses on the terrestrial applications.However,the well-developed emerging technologies in 5G are hardly applied to the maritime communications,resulting from the lack of communication infrastructure deployed on the vast ocean,as well as different characteristics of wireless propagation environment over the sea and maritime user distribution.To satisfy the expected plethora of broadband communications and multimedia applications on the ocean,a brand-new maritime information network with a comprehensive coverage capacity in terms of all-hour,all-weather,and all-sea-area has been expected as a revolutionary paradigm to extend the terrestrial capacity of enhanced broadband,massive access,ultra-reliable,and low-latency to the vast ocean.Further considering the limited available resource of maritime communication infrastructure,the convergence of broadband and broadcast/multicast can be regarded as a possible yet practical solution for realizing an efficient and flexible resource configuration with high quality of services.Moreover,according to such multi-functionality and all-coverage maritime information network,the monitoring and sensing of vast ocean area relying on massive Ocean of Things and advanced radar techniques can be also supported.Concerning these issues above,this study proposes a Software Defined Networking(SDN)based Maritime Giant Cellular Network(MagicNet)architecture for broadband and multimedia services.Based on this network,the convergence techniques of broadband and broadcast/multicast,and their supporting for maritime monitoring and marine sensing are also introduced and surveyed.

A new family of two-dimensional triple-codeweight asymmetric optical orthogonal code for OCDMA networks

A new generation algorithm of two-dimensional triple-codeweight asymmetric optical orthogonal codes for optical code division multiple access （OCDMA） networks is proposed. The code cardinality is obtained and the error-probability performance for corresponding OCDMA system is analyzed. The codes with two constraints （i.e., auto- and cross-correlation properties） being unequal are taken into account. On the premise of fixed system resources, the code of the error-probability performance, it is shown cardinality can be significantly improved. By analysis that the codes with different parameters have different performances. Therefore, this type of codes can be applied to support diverse quality of service （QoS） and satisfy the quality requirement of different multimedia or distinct users, and simultaneously make the better use of bandwidth resources in oDtical networks.

A Semantics-Based Approachfor Achieving Self Fault-Tolerance of Protocols

The cooperation of different processes may be lost by mistake when a protocol is executed. The protocol cannot be normally operated under this condition. In this paper,the self fault-tolerance of protocols is discussed, and a semanticsbased approach for achieving self fault-tolerance of protocols is presented. Some main characteristics of self fault-tolerance of protocols concerning liveness, nontermination and infinity are also presented. Meanwhile, the sufficient and necessary conditions for achieving self fault-tolerance of protocols are given. Finally, a typical protocol that does not satisfy the self fault-tolerance is investigated, and a new redesign version of this existing protocol using the proposed approach is given.

Two-Way Digital Video Transmission over Medium-Voltage Power-Lines Using Time-Domain Synchronous Orthogonal Frequency Division Multiplexing Technology

This paper describes field trials of two-way digital video transmissions over a 700-m long medium-voltage power cable using a frequency division duplex scheme. The purpose is to check the feasibility of using time-domain synchronous orthogonal frequency division multiplexing （TDS-OFDM） technology in powerline communication （PLC）. TDS-OFDM is the core technology in digital multimedia broadcasting-terrestrial （DMB-T）, developed by Tsinghua University for digital television terrestrial multimedia broadcast applications and successfully adopted in the Chinese Digital Terrestrial Television Broadcasting Standard. PLC systems are widely believed to be bandwidth or data throughput limited. However, the use of known pseudo random sequences as guard intervals for synchronization and channel estimation in TDS-OFDM greatly reduces the system overhead and increases the spectrum efficiency. These experiments show that TDS-OFDM is appropriate not only for broadcasting but also for PLC applications with appropriate modifications.