Efficient channel borrowing strategy for real-time services inmultimedia wireless networks

An efficient resource sharing strategy is proposed for multimedia wireless networks. We assume the channel resource in a wireless system is partitioned into two sets: one for voice calls and one for video calls. In the proposed channel borrowing strategy, voice calls can borrow channels from those pre-allocated to video calls temporarily when all voice channels are busy. A threshold type decision policy is designed such that the channel borrowing request will be granted only if the quality of service (QoS) requirement on video call blocking will not be violated during the duration of channel lending. An analytical model is constructed for evaluating the performance of the channel borrowing strategy in a simplified wireless system and is verified by computer simulations. We found that the proposed channel borrowing scheme can significantly reduce the voice call blocking probability while the increase in video call blocking probability is insignificant     

Call admission control for mobile multimedia communications withtraffic asymmetry between uplink and downlink

The call admission control (CAC) for mobile communications is one of the most important engineering issues since it belongs to the category of resource management and the radio spectrum is a very scarce resource. In future mobile cellular systems, the CAC scheme should be efficient for multimedia services as well as for voice services. This paper proposes an advanced CAC scheme for mobile multimedia communications. A characteristic of the proposed scheme is that it takes account of the traffic (load) asymmetry between uplink and downlink in mobile multimedia environments, we evaluate the performance of the proposed scheme using Markov analysis. The performance measures on which we focus are the utilization of resources and the blocking probabilities of handoff calls and new calls. We present some numerical examples with practically meaningful parameter values. As a result, we show that the proposed CAC scheme can be a good choice for mobile multimedia systems such as the International Mobile Telecommunications-2000 systems     

Applications of voice processing to telecommunications

The ways in which people communicate are changing rapidly. The options are many and diverse, ranging from voice calls over wireless networks, to video calls over the conventional wired network, ISDN video, FAX, e-mail, voice mail, beeper services, data services, audio teleconferencing, video teleconferencing, and so-called scribble phone service (transmission of arbitrary handwritten input). This revolution in communications is being fueled by several sources, including the availability of low-cost, low-power, computation in both DSP and RISC chips, larger and cheaper memory chips, improved algorithms for communications (e.g., modems, signaling) and signal processing, and finally the creation of world-wide standards for transmission, signal compression, and communication protocols. The broad goal of the communications revolution is to provide seamless and high-quality communications between people (or groups of people), anywhere, anytime, and at a reasonable price. Although there are many technologies that form the bases for the communications environment of the twenty-first century, one of the key technologies for making the vision a reality is voice processing. In this paper we attempt to show, by example, how voice processing has been applied to specific problems in telecommunications, and how it will grow to become an even more essential component of the communications systems of the twenty-first century     

多媒体通信综述

本文在简述了语音、数据及视频等信息处理技术和传输、组网等网络技术的基础上,着重介绍了多媒体通信业务的应用,主要包括;视频电子信箱,远程医疗诊断、计算机辅助设计,数字网络图书馆,多媒体会议系统,高清晰度图像系统和视频点播等。文章最后还简单介绍了国内外多媒体通信业务发展的情况。     

移动视频电话业务平台的建设

移动视频电话业务是一种集视频、语音于一体的多媒体通信业务,移动用户之间能够进行实时音、视频的交互,本文阐述移动视频电话业务平台的体系架构、建设方案及新的多媒体业务的引入。     

Models for storing and presenting multimedia documents

This paper deals with models for storing and presenting multimedia documents integrating large amounts of data of different types. Usually, multimedia systems integrate a variety of data such as voice, graphics, text video and other types of images into a single document. Most of these data are not structured and therefore require a huge storage capacity. Such a requirement causes many problems for traditional database management systems which were not originally designed to manipulate data other than text. The presentation of multimedia documents incorporates documentary research that depends upon storage model and mechanisms. In this paper, we present two data storage models and several other associated models for the presentation of multimedia documents. The analysis of these models reveals their capacity to synchronize various temporal scenarios while allowing users simultaneous and secure access to multimedia systems.     

Output and delay process analysis for slotted CDMA wirelesscommunication networks with integrated voice/data transmission

This paper presents the output and delay process analysis of integrated voice/data slotted code division multiple access (CDMA) network systems with random access protocol for packet radio communications. The system model consists of a finite number of users, and each user can be a source of both voice traffic and data traffic. The allocation of codes to voice calls is given priority over that to data packets, while an admission control, which restricts the maximum number of codes available to voice sources, is considered for voice traffic so as not to monopolize the resource. Such codes allocated exclusively to voice calls are called voice codes. In addition, the system monitoring can distinguish between silent and talkspurt periods of voice sources, so that users with data packets can use the voice codes for transmission if the voice sources are silent. A discrete-time Markov process is used to model the system operation, and an exact analysis is presented to derive the moment generating functions of the probability distributions for packet departures of both voice and data traffic and for the data packet delay. For some cases with different numbers of voice codes, numerical results display the correlation coefficient of the voice and data packet departures and the coefficient of variation of the data packet delay as well as average performance measures, such as the throughput, the average delay of data packets, and the average blocking probability of voice calls     

LTE Part I: Core network

Current cellular networks based on Third Generation Partnership Project (3GPP) and 3GPP2 technologies provide evolution from circuit-switched technologies, originally developed for voice communications, to packetswitched technologies. Next-generation networks need to deliver IP-based services (voice, video, multimedia, data, etc.) for all kinds of user terminals while moving between fixed (fiber, DSL, cable) and wireless (3GPP-based, 3GPP2-based, IEEE-based) access technologies, and roaming between various operator networks. Users expect the network to originate, terminate, and maintain a session while the user is moving and roaming. Services have to be delivered to users based on serving network functionality (quality of service [QoS], bandwidth, etc.), availability, and user preferences. The network and users must be protected through various authentication, encryption, and other security mechanisms at the access, network, and application layers. Mobility has to be provided through coordinated link, network, and application layer mobility mechanisms that ensure user expectations of service performance are met. Requirements on the radio technology include improved performance as well as reduced system and device complexity. 3GPP Release 8 specifies the architecture to meet the above requirements.     

High-Speed Packet Switching Systems for Multimedia Communications

High-speed packet switching (HPS) systems can Provide flexible, economical, high-quaiity services for integrated voice, video, and data communications. To realize such HPS systems, methods have been developed to bring about high-speed protocol processing as well as a system architecture for facilitating high-throughput switching. Adopting the parallel processing algorithm into protocol processing allows us to achieve high-speed packet protocol processing of about 100 times faster than conventional processing. Furthermore, a fully distributed system architecture in addition to hierarchical interconnection networks can achieve high-capacity packet switching systems. The proposed HPS system is thus capable of accommodating lines of up to 10-50 Mbits/s, of providing high-throughput switching capability of 1 000 000 packets/s, and of having an average delay of less than 2 ms. Furthermore, an evaluation of network delay performances of video conferencing and voice communications indicate that HPS systems are quite suitable for handling such multimedia communications.     

Motivations for using the mobile phone for mass communications and entertainment

This study draws on the uses and gratifications framework to examine expanded use of a hybrid medium—the mobile phone—for mass communications and entertainment. Results of a telephone survey of 208 users show different motivations predict diverse uses of the mobile phone. Instrumental use motives drive the use of the mobile phone for news-seeking and Web-surfing. Further, the motive of pass time is significantly linked to playing video games via the mobile phone. In addition, the high-tech mobile phone enabled users to be more active: the more intensively people use mobile phones for voice calls, the more likely they will be to use mobile data services. Thus, the hybrid mobile phone bridges interpersonal and mass communication. Finally, younger users are more likely to use mobile phones for getting news and entertainment. Implications for the industry and recommendations for future research are discussed.     

Why isoEthernet will change the voice and video worlds

The answers to many of the communications problems businesses face lie in the integration of telephony, data collaboration, and video communications with the desktop computer, doing it inexpensively, doing it seamlessly with the local area and wide area networks. The adoption of isochronous Ethernet (isoEthernet) by the IEEE 802.9 committee as the new multimedia standard in LANs has given rise to new technology that converges voice, collaborative video, and data at the desktop. The official name for isoEthernet is ISLAN16-T, and it is sponsored by the IEEE 802.9 committee. IEEE 802.9a, the document specifying the isoEthernet standard, became an official standard at the end of 1995. The intent behind the ISLAN16-T standard is to define a LAN transport capable of handling synchronous services such as voice and video while retaining compatibility with 10Base-T. ISLAN16-T opens the door to a multitude of new applications that can reshape work and communications habits to make businesses more productive, responsive, and profitable     

A packet reservation multiple access (PRMA)-based algorithm for multimedia wireless system

The major issue in the wireless multimedia system design is the selection of a suitable channel sharing media access control (MAC) protocol. The design challenge is to identify a wireless "multimedia capable" MAC protocol that provides a sufficient degree of transparency for many different kinds of services. This protocol should guarantee different quality of service (QoS) parameters for different types of traffic while in the same time achieving high throughput. In this paper a MAC protocol to serve different kinds of traffic, namely voice, data, and, real time variable bit rate (rt-VBR) video is proposed. The transmission time scale is divided into frames. Each frame is subdivided into N time slots. In this protocol, a fixed number of slots M out of 150 time slots are reserved at the beginning of every frame to transmit some of the video packets arriving during the frame interval. The rest of the video packets contend with the voice and data packets for the remaining time slots of this frame as in normal packet reservation multiple access (PRMA). One objective of this paper is to find the optimum value of M allowing the maximum number of voice and data users to share the RF channel with one video user. Another objective is to find the optimum permission probabilities of sending contending voice, data, and video packets allowing the maximum number of users sharing the RF channel. The dropping probability requirement for video is examined.     

统一通信简述

随着通信技术的快速发展和企业通信基础设施的建设,用户尤其是企业用户提出了更多的业务要求。统一通信业务提供了一个融合语音、数据、多媒体的业务解决方案,使得用户任何时候,任何地点都能灵活的使用各种通信业务。一个好的统一通信业务平台包括VoIP通信能力、呈现业务能力、即时消息业务能力以及众多的业务。同时为了实现和企业基础设施无缝的融合,统一通信业务平台可以提供开放的业务接口。     

The role of teletraffic modeling in the new communicationsparadigms

Teletraffic engineers provide models allowing communications networks to be planned and systems to be designed to meet the performance needs of users within a reasonable cost. The successful modeler combines analytical or simulation skills with a deep understanding of the technology. In the emerging information networking environment comprising new technologies such as ATM, Internet, wireless, etc., and new services such as video, multimedia, data and personal communications services, the old paradigms of circuit-switched calls and Erlang distributions have been severely challenged. The confluence of the shifts in technologies and services along with the convergence of computing, telecommunications, consumer electronics, and electronic media industries, and the shift from a monopolistic to competitive business paradigm, has created a tremendously rich lode of fundamental problems that need to be addressed by teletraffic engineers. In this article the author describes the historical role of the teletraffic engineer, reviews several of the major paradigm shifts, and discusses some of the challenges facing the teletraffic community with an emphasis on modeling wireless communications systems     

Probability of error in a spread spectrum network with variable bit rate and constant chip rate

The local communications network of the future will be a single-mode fibre optic network handling voice, data, and high resolution video. A reasonable approach to the problem of interfacing the wide variety of users to such a network is by means of electrical sub-networks. This paper deals with frequency hopping spread spectrum sub-networks with user equipment (devices) of variable rates and a constant chip rate. In such a network, there can be three types of users: slow-frequency hopped, simple-frequency hopped and fast-frequency hopped users. This paper investigates the probabilities of bit losses for all three types of users in such a sub-network.     

Multipath video transport over ad hoc networks

Real-time multimedia transport has stringent bandwidth, delay, and loss requirements. It is a great challenge to support such applications in wireless ad hoc networks, which are characterized by frequent link failures and congestion. Using multiple paths in parallel for a real-time multimedia session (called multipath transport) provides a new degree of freedom in designing robust multimedia transport systems. In this article, we describe a framework for multipath video transport over wireless ad hoc networks, and examine its essential components, including multistream video coding, multipath routing, and transport mechanisms. We illustrate by three representative examples how to extend existing video coding schemes in order to fully explore the potential of multipath transport. We also examine important mechanisms in different layers for supporting multipath video transport over ad hoc networks. Our experiments show that multipath transport is a promising technique for efficient video communications over ad hoc networks.     

Novel multimedia traffic modeling based CAC scheme for CDMA communication systems

As the radio spectrum is a very scarce resource, the Call Admission Control （CAC） is one of the most important parts in radio resource management. The Code Division Multiple Access （CDMA） based next generation wireless communications systems will support the transmission of multimedia traffic, such as voice, video and data, thus the CAC, which can support the multimedia traffic and guarantee the Quality of Service （QoS） of different traffic, has gained broad attention. In this paper, a novel multimedia traffic modeling method and a corresponding dynamic QoS based CAC are proposed. The analysis and simulation results show that the proposed CAC scheme can guarantee the QoS to different traffic demand, and improve the system performance significantly.     

多媒体通信的发展趋势

回顾了视频压缩标准、数据会议、多媒体终端及多媒体网络应用平台的发展概况,阐述了多媒体通信的发展趋势:集语音、视频、数据和Web会议的一体化协作通信平台.     

Performance analysis of cellular mobile communication networks supporting multimedia services

This paper illustrates the development of an analytical model for a communication network providing integrated services to a population of mobile users, and presents performance results to both validate the analytical approach, and assess the quality of the services offered to the end users. The analytical model is based on continuoustime multidimensional birth–death processes, and is focused on just one of the cells in the network. The cellular system is assumed to provide three classes of service: the basic voice service, a data service with bit rate higher than the voice service, and a multimedia service with one voice and one data component. In order to improve the overall network performance, some channels can be reserved to handovers, and multimedia calls that cannot complete a handover are decoupled, by transferring to the target cell only the voice component and suspending the data connection until a sufficient number of channels become free. Numerical results demonstrate the accuracy of the approximate model, as well as the effectiveness of the newly proposed multimedia call decoupling approach.