基于SIP协议的互联网音频传输浅谈

随着互联网技术的快速发展,广电行业音频实时传输的技术也日益更新。特别是近年来IP技术普遍应用,使得研究IP技术在专业广电领域实现数字音频实时传输势在必行。使用低成本、适应局域网网络环境、高可用性的SIP协议。

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.

A NOVEL CALL ADMISSION CONTROL SCHEME IN CELLULAR/WLAN INTEGRATION AND PERFORMANCE ANALYSIS

In order to achieve the Quality of Service(QoS) provisioning and efficient resource utili-zation in cellular network and Wireless Local Area Network(WLAN) integration,an Integrated Ser-vice-Based Call Admission Control(ISB-CAC) scheme is proposed in this paper.The integrated network is modeled by using multi-dimensional Markov chains.The numerical analysis is presented to evaluate the important performance measures such as the blocking probability of originating calls,the dropping probability,and the average transfer time,etc.The steady-state probabilities of the multi-dimensional Markov chains are obtained by using an iterative approach,and the CAC pa-rameters are optimally designed.The analytical model is validated by the computer simulation.It is shown that compared with the conventional WLAN-First Call Admission Control(WF-CAC) scheme,the proposed ISB-CAC scheme not only provides better QoS for mobile users but also utilizes the bandwidth resources more efficiently.

A novel dynamic call admission control policy for wireless network

To address the issue of resource scarcity in wireless communication, a novel dynamic call admission control scheme for wireless mobile network was proposed. The scheme established a reward computing model of call admission of wireless cell based on Markov decision process, dynamically optimized call admission process according to the principle of maximizing the average system rewards. Extensive simulations were conducted to examine the performance of the model by comparing with other policies in terms of new call blocking probability, handoff call dropping probability and resource utilization rate. Experimental results show that the proposed scheme can achieve better adaptability to changes in traffic conditions than existing protocols. Under high call traffic load, handoff call dropping probability and new call blocking probability can be reduced by about 8%, and resource utilization rate can be improved by 2%-6%. The proposed scheme can achieve high source utilization rate of about 85%.

Reservation-based dynamic admission control scheme for wideband code division multiple access systems

Call admission control (CAC) and resource reservation (RR) for mobile communication are two important factors that guarantee system efficiency and quality of service (QoS) required for different services in a very scarce resource as the radio spectrum. A new scheme was proposed which extends the concepts of resource sharing and reservations for wideband code division multiple access (WCDMA) systems with a unique feature of soft capacity. Voice and data traffic were considered. The traffic is further classified into handoff and new requests. The reservation thresholds were dynamically adjusted according to the traffic pattern and mobility prediction in order to achieve the maximum channel utilization, while guaranteeing different QoS constraints. The performance of proposed scheme was evaluated using Markov models. New call blocking probability, handoff call dropping probability, and channel utilization were used as benchmarks for the proposed scheme.

Organizational Change and Dynamics of Control： An Analysis of Italian Call Center Workplace

The main goal of the paper is to interpret the concept of organizational change in the perspective of critical management studies, by analyzing both the discourses and the control practices used by management. We aim at denaturalize the concept of change related to transition from a bureaucratic model to a professional （post-bureaucratic） model of the call centers organizational design, showing how these discourses and practices reproduce control systems. For this purpose, two cases study of call center outsourced industry are presented. On one hand, we emphasize the bureaucratic nature of call center A associated with standardization of processes and products and where work is highly controlled and routinised. On the other hand, we observe a different image of call center： call center B can be described as a place where work is customized, workers are considered key resources with higher competences and skills that are able to give customers unique solutions and to give answer to complex questions. We suggest that these ＂new practices＂ and ＂new organizational approaches＂ are merely illusions of change. We argue that in professional model （call center B）, control institutionalized through technology is strengthened and deepened by the use of post-bureaucratic control in shaping organizational behaviors, reproducing a Panopticon structure both in terms of electronic surveillance and in terms of behavioral （self） regulation and discipline

A Novel Effective Bandwidth Based Call Admission Control for Multimedia CDMA Systems

A novel Call Admission Control(CAC)scheme is proposed for multimedia CDMA systems.The effectivebandwidth of real time calls is reserved in the CAC with the consideration of active factors.The admission of non-real timecalls is controlled by the system according to the residual effective bandwidth left from real time calls.Simulation resultshave shown that the novel CAC has greatly enlarged the admission region for real time calls and make the transmission de-lay of non-real time calls under an acceptable level.