Performance Analysis for Multimedia Communication Systems with a Multilayer Queuing Network Model

Software performance evaluation in multimedia communication systems is typically formulated into a multi-layered client-server queuing network(MLCSQN) problem. However, the existing analytical methods to MLCSQN model cannot provide satisfactory solution in terms of accuracy, convergence and consideration of interlocking effects. To this end, this paper proposes a heuristic solving method for MLCSQN model to boost the performance prediction of distributed multimedia software systems. The core concept of this method is referred to as the basic model, which can be further decomposed into two sub-models: client sub-model and server sub-model. The client sub-model calculates think time for server sub-model, and the server sub-model calculates waiting time for client sub-model. Using a breadthfirst traversal from leaf nodes to the root node and vice versa, the basic model is then adapted to MLCSQN, with net sub-models iteratively resolved. Similarly, the interlocking problem is effectively addressed with the help of the basic model. This analytical solver enjoys advantages of fast convergence, independence on specific average value analysis(MVA) methods and eliminating interlocking effects.Numerical experimental results on accuracy and computation efficiency verify its superiority over anchors.

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

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.

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.

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.

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.

Reliable Content Distribution in P2P Networks Based on Peer Groups

Peer-to-Peer (P2P) networks are highly dynamic systems which are very popular for content distribution in the Internet. A single peer remains in the system for an unpredictable amount of time, and the rate in which peers enter and leave the system, i.e. the churn, is often high. A user that is obtaining content from a selected peer is frequently informed that particular peer is not available anymore, and is asked to select another peer, or will have another peer assigned, often without enough checks to confirm that the content provided by the new peer presents the same quality of the previous peer. In this work we present a strategy based on group communication for transparent and robust content access in P2P networks. Instead of accessing a single peer for obtaining the desired content, a user request is received and processed by a group of peers. This group of peers, called PCG (Peer Content Group) provides reliable content access in sense that even as members of the group crash or leave the system, users continue to receive the content if at least one group member remains fault-free. Each PCG member is capable of independently serving the request. A PCG is transparent to the user, as the group interface is identical to the interface provided by a single peer. A group member is elected to serve each request. A fault monitoring component allows the detection of member crashes. If the peer is serving request crashes, another group member is elected to continue providing the service. The PCG and a P2P file sharing applications were implemented in the JXTA platform. Evaluation results are presented showing the latency of group operations and system components.

Algorithm for Delay-Constrained Minimal Cost Group Multicasting

Group multicast routing algorithms satisfying quality of service requirements of real-time applications are essential for high-speed networks. A heuristic algorithm was presented for group multicast routing with bandwidth and delay constrained. A new metric was designed as a function of available bandwidth and delay of link. And source-specific routing trees for each member were generated in the algorithm by using the metric, which satisfy member′s bandwidth and end-to-end delay requirements. Simulations over random network were carried out to compare the performance of the proposed algorithm with that from literature.Experimental results show that the algorithm performs better in terms of network cost and ability in constructing feasible multicast trees for group members. Moreover,the algorithm can avoid link blocking and enhance the network behavior efficiently.

Improvisation of Node Mobility Using Cluster Routing-based Group Adaptive in MANET

In today's Internet routing infrastructure,designers have addressed scal-ing concerns in routing constrained multiobjective optimization problems examining latency and mobility concerns as a secondary constrain.In tactical Mobile Ad-hoc Network(MANET),hubs can function based on the work plan in various social affairs and the internally connected hubs are almost having the related moving standards where the topology between one and the other are tightly coupled in steady support by considering the touchstone of hubs such as a self-sorted out,self-mending and self-administration.Clustering in the routing process is one of the key aspects to increase MANET performance by coordinat-ing the pathways using multiple criteria and analytics.We present a Group Adaptive Hybrid Routing Algorithm(GAHRA)for gathering portability,which pursues table-driven directing methodology in stable accumulations and on-request steering strategy for versatile situations.Based on this aspect,the research demonstrates an adjustable framework for commuting between the table-driven approach and the on-request approach,with the objectives of enhancing the out-put of MANET routing computation in each hub.Simulation analysis and replication results reveal that the proposed method is promising than a single well-known existing routing approach and is well-suited for sensitive MANET applications.

Lightweight Trusted Security for Emergency Communication Networks of Small Groups

Public communication infrastructures are susceptible to disasters. Thus, the Emergency Communication Networks(ECNs) of small groups are necessary to maintain real-time communication during disasters. Given that ECNs are self-built by users, the unavailability of infrastructures and the openness of wireless channels render them insecure. ECN security, however, is a rarely studied issue despite of its importance. Here, we propose a security scheme for the ECNs of small groups. Our scheme is based on the optimized Byzantine Generals’ Problem combined with the analysis of trusted security problems in ECNs. Applying the Byzantine Generals’ Problem to ECNs is a novel approach to realize two new functions, debugging and error correction, for ensuring system consistency and accuracy. Given the limitation of terminal devices, the lightweight fast ECDSA algorithm is introduced to guarantee the integrity and security of communication and the efficiency of the network. We implement a simulation to verify the feasibility of the algorithm after theoretical optimization.

群组通信研究

计算机网络的发展使通过网络相连的计算机集合成为一个相互协调的统一整体，并为人类群体成员间的协作配合提供新的工具。目前计算机网络中有关群组通信的研究十分活跃，是计算机网络研究的关键技术之一。群组通信（ＧｒｏｕｐＣｏｍｍｕｎｉｃａｔｉｏｎ）为分布式文件系统、分布式数据库系统、并行计算、容错系统和计算机协同工作系统等各种分布式应用系统提供所需的通信服务。本文从数据传输的角度分析了群组通信的特征，提出了群组通信的体系结构，并综述了相关的最新研究成果。群组通信要解决的主要问题包括：（１）扩展主机和路由器功能，以支持多目标分组的发送、转发和接收。（２）引入资源预留机制，以有效地控制网络带宽等资源的分配。（３）提供可靠群组通信机制。（４）利用群组通信功能提供各种应用系统所需的通信服务。

Covert voice over internet protocol communications based on spatial model

This paper presents a new spatial steganography model for covert communications over voice over internet protocol(Vo IP), providing a solution to the issue of increasing the capacity of covert Vo IP channels without compromising the imperceptibility of the channels. Drawing from Orthogonal Modulation Theory in communications, the model introduced two concepts, orthogonal data hiding features and data hiding vectors, to covert Vo IP communications. By taking into account the variation characteristics of Vo IP audio streams in the time domain, a hiding vector negotiation mechanism was suggested to achieve dynamic self-adaptive steganography in media streams. Experimental results on Vo IP steganography show that the proposed steganographic method effectively depicted the spatial and temporal characteristics of Vo IP audio streams, and enhanced robustness against detection of steganalysis tools, thereby improving the security of covert Vo IP communications.

An Analysis of Network Sports News Reporting from the Perspective of Communication Studies

This paper explores network sports news reporting from a communication studies perspective,analyzing its impact,challenges,and future prospects.It highlights the influence of digital tools,multimedia content,and social media on sports news dissemination.The study also delves into audience engagement,content analysis,and ethical concerns.Ultimately,it emphasizes the need for technological adaptation,media education,and policy development to ensure the continued evolution of network sports news reporting in the digital era.

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.

Social network structures among the livestock farmers vis a vis calcium supplement technology

This study aims to delineate and analyze the configuration of social networks of farmers with respect to the acquisition of information on vital livestock technology.Three stage sampling was carried out by interviewing 320 technology-adopter farmers from four districts of Kerala State in India.For mapping the network,social network analysis(SNA)was used,which revealed the important sources as well as patterns of information access by farmers.Results established the predominance of a formal communication source(veterinary doctor)in the study locales followed by small-sized peer groups of livestock farmers for crucial information support on technology use.The trend is observed irrespective of their gender in various study areas.Significantly the study thus,underscored the role of homogenous peer groups of farmers in facilitating meaningful interactions as well as information sharing on the technology.Given the low level of adoption of most livestock technologies along with the weak livestock extension machinery in the country,these findings could be used by extension agencies to strategize future technological interventions.