Media handling for multimedia conferencing in multihop cellular networks

This article addresses the media-handling aspects of multimedia conferencing in multihop cellular networks. Participation in multimedia conferences in MCNs may be confined to either the conventional cellular network or the MANET. Participation also can span both networks. However, neither the media-handling architectures currently in use in conventional cellular networks, nor the ones in use in MANETs are appropriate. When they are used, either the participants in the conventional cellular network, or the ones in the MANETs, might experience long and potentially unacceptable end-to-end stream delays. Furthermore, these architectures are the antipodes of each other. Reconciling them is not an easy task. We evaluate the architectures currently in use in cellular networks and MANETs, show that none is suitable, and propose a new architecture that bridges the two worlds. The new architecture uses the MANET media-handling architectures as a starting point. It is based on media mediators. A media mediator is composed of two functional entities: the media gateway controller mediator and the media gateway mediator. A proof-of-concept prototype was implemented, and extensive simulations were conducted to evaluate performance.     

Desktop conversations — the future of multimedia conferencing

Both the recent explosion of interest in the Internet and the ongoing development of video-on-demand services have focused attention on the retrieval and delivery aspects of telecommunications networks. Yet the telephony network is fundamentally based on a much more basic human need — two-way communication. In fact, people normally communicate using conversation — interactive speech plus additional information in the form of non-verbal cues like body language.The underlying technologies and standards to enable the easy exchange of information in a conversational way are now converging — which brings together the fields of conferencing, multimedia, and telephony into a unified whole. This could well be the catalyst to turning data communications into the dominant conversational medium of the future.This paper looks at the ways that the desktop may soon rival the telephone as the natural route for carrying out a media-rich conversation with a remotely located person, and focuses on one example of a desktop conferencing application — Passepartout.     

基于SIP的多媒体会议分布式管理架构的设计

与会者及设备在地理上多处分布的大规模多媒体会议系统的一个重要设计思想就是要提高会议管理架构的可伸缩性.文章介绍了基于会话初始协议(SIP)的多媒体会议分布式管理架构的设计,并将策略管理技术引入到分布式管理架构中,从而为解决会议系统的缩放性、扩展性问题提供了一种新途径.     

一种4G网络中多媒体业务的建模方法

4G网络数据业务中,无线资源管理的分组调度性能和业务源模型关系密切。为了更好地分析4G网络的系统性能,建立准确的业务源模型十分关键,尤其针对基于HTTP协议的网页浏览业务,该业务已在人们日常生活当中发挥了不可替代的作用,具有很高的研究和实用价值。结合4G网络的特性,对4G移动多媒体应用下的HTTP网页浏览业务进行了建模与分析,进而通过实际抓包分析了该业务的特性,并得到了各个参数的分布模型,最后,实验结果与理论建模匹配很好。     

QoS-oriented access control for 4G mobile multimedia CDMAcommunications

An efficient medium access control protocol with fair packet loss sharing packet scheduling is proposed for wireless code-division multiple access communications. The proposed MAC protocol exploits both time-division and code-division statistical multiplexing. The FPLS scheduler uses the information of traffic rate distribution and quality of service requirements to assign priorities to the users and determines an efficient combination of the packets for transmission in the time slots of each frame, so the number of the served users is maximized under the QoS constraints. Simulation results demonstrate the effectiveness of the FPLS scheduler, in comparison with other previously proposed scheduling algorithms     

Quality Assessment in 3G/4G Wireless Networks

The convergence of wireless networks and multimedia communications, linked to the swift development of services and the increasing competition, has caused user expectations of network quality to raise. Network quality has become one of the main targets for the network optimization and maintenance departments. Quality of experience (QoE) has been traditionally assessed via subjective tests, but this is a costly method. In recent years, different methods for assessing QoE from objective parameters have been proposed. In this paper we describe a non-intrusive system for the analysis and measurement of QoE in wireless networks from these objective parameters. The system consists of mobile agents running on the mobile terminals and one or more network entities that collect and analyze the information.     

Provisioning multimedia wireless networks for better QoS: RRM strategies for 3G W-CDMA

Third-generation mobile communication systems will bring a wide range of new services with different quality of service requirements and will open the ability to exploit radio resource management functions to guarantee a certain target QoS, to maintain the planned coverage area and to offer a high-capacity while using the radio resources in an efficient way. RRM functions impact the overall system efficiency and the operator infrastructure cost, so they will definitively play an important role in a mature 3G scenario. In order to provide some insight into radio resource management (RRM) strategies implementation, a range of representative case-studies with several innovative algorithms are presented and supported by simulation results in a realistic UMTS Terrestrial Radio Access Network scenario as devised in the 3GGP standardization forum. In particular, a decentralized uplink transmission rate selection algorithm in the short term, a congestion control mechanism to cope with overload situations, and downlink scheduling for layered streaming video packets are proposed.     

Enabling multimedia applications in 2.5G and 3G wireless terminals through a combined RISC/DSP architecture: OMAP

This paper describes how multimedia applications will be enabled in 2.5 and 3G wireless terminals thanks to the efficiency of the DSP core embedded in the TI OMAP platform. OMAP H/W architecture will be described with an emphasis on how multimedia applications (video, audio, speech) will benefit from this advanced architecture. The advantages provided by a combined RISC/DSP architecture, compared to a single RISC architecture, for multimedia mobile applications will be depicted.     

Signalling analysis in integrated 4G networks

Scarce radio resources and the ambition to increase the number of mobile customers with a guarantee of service are pushing mobile communication systems from homogeneous non‐service convergent 2G and convergent‐service 2.5G and 3G wireless systems to heterogeneous integrated and convergent service 4G networks. This evolution has had several consequences from network design, control and service management points of view. In the emerging integrated 4G networks one of the issues is the signalling of information related to different control purposes such as QoS, mobility and security signalling. In fact, some questions such as which are the candidate signalling protocols, and which approach of integrated signalling to be adopted (unified versus non‐unified) need to be considered in the context of the emerging 4G integrated network. This is precisely the scope of this paper. We first identify the requirements related to mobility, security/AAA and QoS signalling, then we consider candidate signalling protocols and we propose possible approaches in the integration of signalling in the context of 4G networks. Copyright © 2006 John Wiley & Sons, Ltd.     

Efficient resource allocation for China's 3G/4G wireless networks

The all-IP DiffServ model is expected to be the most promising architecture for QoS provisioning in China's next-generation wireless networks, due to its scalability, convenience for mobility support, and capability of interworking heterogeneous radio access networks. This article focuses on efficient resource allocation in a wireless DiffServ architecture. Resource utilization efficiency is particularly important for China's wireless networks as the mobile user density in China is and will continue to be much higher than that in other countries. More specifically, we propose a novel buffer sharing scheme to provide assured service for real-time layer-coded multimedia traffic, which can guarantee the specific packet loss requirement of each layer with UDP as the transport layer protocol. An adaptive optimal buffer configuration can be applied to achieve maximum resource utilization over the time-varying channel. Assured service is also provided to TCP data traffic for guaranteed throughput, where the cross-layer coupling between the TCP layer and link layer is exploited to efficiently utilize the wireless resources.     

让移动多媒体成为中国3G的前奏

随着移动通信技术的迅猛发展,移动多媒体逐渐成为新的发展方向之一.据有关专家机构预测,到2008年,彩屏、嵌入式数码相机、和弦铃声都将成为标准的配置,移动多媒体芯片和业务市场规模将分别达到数十亿和数百亿美元.     

Media handling aspects of multimedia conferencing in broadband wireless ad hoc networks

The emergence of broadband wireless technologies has made broadband wireless ad hoc networks a reality. Broadband wireless ad hoc networks are infrastructure-less and can be used in a wide range of scenarios in private, public, commercial, and military settings. Multimedia conferencing is an important application area. Its two main components are signaling and media handling. This article focuses on the media handling aspects or multimedia conferencing in broadband wireless ad hoc networks, with a critical review of the state of the art and a proposed novel architecture. The main components of this architecture are a distributed mixing system and a self-organizing system. The distributed mixing system is a two-level structure. The first level is a full mesh network of active nodes that act as media mixers. The second level is made up of passive nodes that rely on the mixers in the first level. Each second-level node is connected to a first-level node. The self-organizing system is based on a resource efficient scheme that provides for the automatic allocation (or deallocation) of mixers when the network grows (or shrinks). Furthermore, it enables the automatic assignment of new nodes to mixers when they join the conference. We have built a proof-of-concept prototype of the architecture and have evaluated the self-organizing system through simulations. We have simulated conferences and observed how mixers are allocated and deallocated. The simulations show that our self-organizing system utilizes resources efficiently in most cases.     

A highly integrated analog front-end for 3G

This paper describes a reconfigurable analog front-end (AFE) and audio codec IC supporting the wideband code division multiple access (WCDMA) standard. The chip is fabricated on Intel's 0.18-/spl mu/m (SOC) flash+logic+analog (FLA) process technology using a 0.35-/spl mu/m feature size analog transistor. The transmit path contains a 10-bit segmented rail-to-rail digital-to-analog converter, automatically tunable active RC filter, and programmable gain amplifier (PGA) with self-tuning gain and offset correction circuit. The receive path incorporates a PGA, active RC filter, and an 8-bit analog-to-digital converter with built-in offset correction. The AFE operates at 2.7 V with a current consumption of 55 mA and total active area of 15 mm/sup 2/.     

FEC在3G多媒体实时传输系统中的应用

3G无线传输是多媒体实时传输的新方式,比传统方式更加灵活、便捷。为了克服在3G无线网络传输中的数据丢包问题,提出了利用FEC和交织来提高数据传输正确率的方法,主要研究了交织和RS(204,188)纠错码的在3G传输系统中的设计和实现,最后对整个系统在不同丢包率信道下的性能进行了对比测试。     

宁夏广播电视台3G/4G电视直播技术的应用

在电视节目制作领域,各大电视台的直播类互动节目屡见不鲜,其节目内容更贴近生活,取得了良好的直播收视效果及社会影响,特别是对突发事件的报道,播出效果尤为突出.宁夏台采用的3G/4G即摄即传直播系统具有传输快、使用简便等特点,将新闻直播间或转播车变成随身携带的一体化设备,新闻直播可以实现快速出击.新的直播系统改变了本台传统的直播工作模式,将原有的电视直播水平推上一个新的台阶.     

A lightweight reconfigurable security mechanism for 3G/4G mobile devices

Wireless communications are advancing rapidly. We are currently on the verge of a new revolutionary advancement in wireless data communications: the third generation of mobile telecommunications. 3G promises to converge mobile technology with Internet connectivity. Wireless data, multimedia applications, and integrated services will be among the major driving forces behind 3G. While wireless communications provide great flexibility and mobility, they often come at the expense of security. This is because wireless communications rely on open and public transmission media that raise further security vulnerabilities in addition to the security threats found in regular wired networks. Existing security schemes in 2G and 3G systems are inadequate, since there is a greater demand to provide a more flexible, reconfigurable, and scalable security mechanism that can evolve as fast as mobile hosts are evolving into full-fledged IP-enabled devices. We propose a lightweight, component-based, reconfigurable security mechanism to enhance the security abilities of mobile devices.     

An 80/20-MHz 160-mW multimedia processor integrated with embeddedDRAM, MPEG-4 accelerator and 3-D rendering engine for mobileapplications

A low-power multimedia processor for mobile applications is presented. An 80-MHz 32-b RISC with enhanced multiplier, two 20-MHz hardware accelerators with 7.125-Mb embedded DRAM for MPEG-4 visual SP@L1 decoding and 3-D graphics processing, 2-kB dual-port SRAM, and peripheral blocks are integrated together on a single chip, MPEG-4 SP@L1 video decoding and 3-D graphics rendering with a 16-b depth-buffer alpha-blending double-buffering and gouraud-shading features at 2, 2-Mpolygons/s speed are realized with the help of the dedicated hardware accelerators/ The architecture of the processor is optimized in terms of power consumption and performance, and various low-power circuit techniques are adopted in each hardware block. The chip is implemented using 0.18-μm embedded memory logic (EML) technology. Its area is 84 mm², and power consumption is 160 mW when all of the functions are activated     

3G核心网电路域信令监测系统分析

本文在分析3G核心网电路域网元及其信令协议特点的基础上,提出了3G核心网信令监测系统的组网架构,信令消息采集和处理方式,可为3G核心网信令监测系统的建设提供参考依据.