OAM (Operations, Administration and Maintenance) system is a very impo rtant component of 3G cellular network. In order to acquire overall managemen t, fast response and steady operation, an SCTP (Stream Control Trans...OAM (Operations, Administration and Maintenance) system is a very impo rtant component of 3G cellular network. In order to acquire overall managemen t, fast response and steady operation, an SCTP (Stream Control Transmission Prot ocol) based OAM, i.e., SOAM system was proposed. SOAM implements new characters of SCTP such as multi-stream, enforced SACK and heartbeat mechanism on its tran sport layer. These characters help SOAM decrease the message transmission delay and accelerate the link failure detection. Besides, a new component named SOAM agent was introduced to improve the operation efficiency of SOAM. The experim ental results prove the proposed SOAM system achieves better performance on sign aling transmission compared with conventional TCP based OAM system.展开更多
In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the prop...In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.展开更多
In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded,...In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.展开更多
Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems enabling terminals and applications to adapt to changes in e.g. context, access network, and a...Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems enabling terminals and applications to adapt to changes in e.g. context, access network, and available Quality-of-Service(QoS) due to mobility of users, devices or sessions. We present the architecture of a multimedia stream adaptation service which enables communication between terminals having heterogeneous hardware and software capabilities and served by heterogeneous networks. The service runs on special content adaptation nodes which can be placed at any location within the network. The flexible structure of our architecture allows using a variety of different adaptation engines. A generic transcoding engine is used to change the codec of streams. An MPEG-21 Digital Item Adaptation (DIA) based transformation engine allows adjusting the data rate of scalable media streams. An intelligent decision-taking engine implements adaptive flow control which takes into account current network QoS parameters and congestion information. Measurements demonstrate the quality gains achieved through adaptive congestion control mechanisms under conditions typical for a heterogeneous network.展开更多
随着我国移动终端的多样化以及人们对网络需求的不断增长,我国移动网络数据的传输数量在近5年增长迅速。然而人们利用移动终端进行网络传输时,通常会受到网络带宽、网络拥塞、网络时延等因素的影响。传统的传输控制协议(Transmission Co...随着我国移动终端的多样化以及人们对网络需求的不断增长,我国移动网络数据的传输数量在近5年增长迅速。然而人们利用移动终端进行网络传输时,通常会受到网络带宽、网络拥塞、网络时延等因素的影响。传统的传输控制协议(Transmission Control Protocol,TCP)与用户数据报协议(User Datagram Protocol,UDP)使用单条路径进行网络传输,已不能很好地满足人们对高速率、实时播放、大吞吐量等网络传输的需求。为了解决这一问题,文章提出一种移动流媒体并行多路传输机制,即多路径传输协议(Multipath Transmission Control Protocol,MPTCP)。该协议可充分发挥多路径传输特性,一方面优化了网络传输的性能,另一方面提高了用户的体验感。展开更多
基金High-Tech Research and DevelopmentProgram of China (No. 2003AA123310)
文摘OAM (Operations, Administration and Maintenance) system is a very impo rtant component of 3G cellular network. In order to acquire overall managemen t, fast response and steady operation, an SCTP (Stream Control Transmission Prot ocol) based OAM, i.e., SOAM system was proposed. SOAM implements new characters of SCTP such as multi-stream, enforced SACK and heartbeat mechanism on its tran sport layer. These characters help SOAM decrease the message transmission delay and accelerate the link failure detection. Besides, a new component named SOAM agent was introduced to improve the operation efficiency of SOAM. The experim ental results prove the proposed SOAM system achieves better performance on sign aling transmission compared with conventional TCP based OAM system.
基金Supported by the National Basic Research Program of China(2012CB720500)the National Supporting Research Program of China(2013BAA03B01)+1 种基金the National Natural Science Foundation of China(21176178)China Scholarship Council(CSC[2015]3022)
文摘In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.
基金Supported by the National Key R&D Program of China(2016YFC1401900)the National Science Foundation of China(61173029,61672144)
文摘In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.
基金Project supported by IST FP6 Integrated Project DAIDALOS (No. IST-2002-506997) and the German Research Foundation (DFG) within the AKOM Framework (No. HA2207/2-3)
文摘Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems enabling terminals and applications to adapt to changes in e.g. context, access network, and available Quality-of-Service(QoS) due to mobility of users, devices or sessions. We present the architecture of a multimedia stream adaptation service which enables communication between terminals having heterogeneous hardware and software capabilities and served by heterogeneous networks. The service runs on special content adaptation nodes which can be placed at any location within the network. The flexible structure of our architecture allows using a variety of different adaptation engines. A generic transcoding engine is used to change the codec of streams. An MPEG-21 Digital Item Adaptation (DIA) based transformation engine allows adjusting the data rate of scalable media streams. An intelligent decision-taking engine implements adaptive flow control which takes into account current network QoS parameters and congestion information. Measurements demonstrate the quality gains achieved through adaptive congestion control mechanisms under conditions typical for a heterogeneous network.
文摘随着我国移动终端的多样化以及人们对网络需求的不断增长,我国移动网络数据的传输数量在近5年增长迅速。然而人们利用移动终端进行网络传输时,通常会受到网络带宽、网络拥塞、网络时延等因素的影响。传统的传输控制协议(Transmission Control Protocol,TCP)与用户数据报协议(User Datagram Protocol,UDP)使用单条路径进行网络传输,已不能很好地满足人们对高速率、实时播放、大吞吐量等网络传输的需求。为了解决这一问题,文章提出一种移动流媒体并行多路传输机制,即多路径传输协议(Multipath Transmission Control Protocol,MPTCP)。该协议可充分发挥多路径传输特性,一方面优化了网络传输的性能,另一方面提高了用户的体验感。
