Real-time video data transmission is currently emerging as a popular application among mobile users but it is very sensitive to QoS degradation due to packet losses in wireless networks.In order to achieve service con...Real-time video data transmission is currently emerging as a popular application among mobile users but it is very sensitive to QoS degradation due to packet losses in wireless networks.In order to achieve service continuity and integrity upon handoffs among heterogeneous networks,provisioning of seamless and secure mobility is required.However,in order to reduce the delay and packet losses during vertical handovers we need to employ supportive protocols like context transfer.In this paper we evaluate the QoS of video transmission over a heterogeneous 3G-WLAN network.The aggregate video data traffic is represented by a dynamic two-dimensional Markov chain model,which has been evaluated against real video data measurement.Upon the vertical handover, appropriate AAA handshaking and enhanced mobility management using context transfer have been considered.Perceived QoS evaluation of video streams was performed based on peak signal-noise ratio(PSNR) measurements,while we analyticallyestimated the number of packet losses during handovers.The results show that both packet loss within the converged network and loss occurrence affecting the perceived video quality is reduced. Moreover,the proposed context transfer scheme minimizes handover delay and the number of lost packet up to 3 times compared to standard AAA handshaking.展开更多
This paper proposes a packet scheduling scheme thatoptimizing the coded video transmission overmultipath wireless multimedia sensor networks interms of received video distortion and power efficiencyenhances the securi...This paper proposes a packet scheduling scheme thatoptimizing the coded video transmission overmultipath wireless multimedia sensor networks interms of received video distortion and power efficiencyenhances the security aspects of the underlyingsystem.When the aggregate transmission rateavailable at the network cannot support the requiredtransmission rate,the scheduling algorithm can selectivelydrop combinations of video packets prior totransmission to adapt the rate of the sender to thelimitations of the wireless channel capacity.Twoscheduling algorithms are proposed.The Baselinescheme utilizes a novel distortion prediction modeland decides upon which packet can be dropped priorto transmission based on the packet’s impact on thevideo distortion.In addition to the bandwidthlimitations,the Power aware packet scheduling is an extension of the Baseline capable of estimating thepower that will be consumed by each node during thetransmission;hence it can control the power consumptionby selectively drop packets of low importanceto the decoded video.Simulation results indicatethe efficiency of the proposed scheduling schemein terms of received video distortion(PSNR)andpower consumption.展开更多
This paper,resents a system called Athlos2,which implements strong access control for athletic events, enhancing the safety feeling of event spectators. Athlos2 integrates intelligent biometric access control systems ...This paper,resents a system called Athlos2,which implements strong access control for athletic events, enhancing the safety feeling of event spectators. Athlos2 integrates intelligent biometric access control systems and smart cards,under a protocol that complies ith the specification of the Liberty Alliance project for federated identities.A pilot version of Athlos2 was deployed and tested in terms of acceptability,information security and performance.展开更多
It is with great pleasure that I am serving as a vip Editor for special issues of the CHINA COMMUNICATIONS JOURNAL on Communications and Information Security in Feb.and June,2007. The goal of these issues is to pres...It is with great pleasure that I am serving as a vip Editor for special issues of the CHINA COMMUNICATIONS JOURNAL on Communications and Information Security in Feb.and June,2007. The goal of these issues is to present the direction that the field has been taking in the last 3-5 years,introduce new展开更多
基金financed by the Greek General Secretariat for Research and Technology(GSRT) grant PENED
文摘Real-time video data transmission is currently emerging as a popular application among mobile users but it is very sensitive to QoS degradation due to packet losses in wireless networks.In order to achieve service continuity and integrity upon handoffs among heterogeneous networks,provisioning of seamless and secure mobility is required.However,in order to reduce the delay and packet losses during vertical handovers we need to employ supportive protocols like context transfer.In this paper we evaluate the QoS of video transmission over a heterogeneous 3G-WLAN network.The aggregate video data traffic is represented by a dynamic two-dimensional Markov chain model,which has been evaluated against real video data measurement.Upon the vertical handover, appropriate AAA handshaking and enhanced mobility management using context transfer have been considered.Perceived QoS evaluation of video streams was performed based on peak signal-noise ratio(PSNR) measurements,while we analyticallyestimated the number of packet losses during handovers.The results show that both packet loss within the converged network and loss occurrence affecting the perceived video quality is reduced. Moreover,the proposed context transfer scheme minimizes handover delay and the number of lost packet up to 3 times compared to standard AAA handshaking.
基金supported by the project PENEDNo. 03636, which is funded in 75% by the European Social Fund and in 25% by the Greek State-General Secretariat for Research and Technology.
文摘This paper proposes a packet scheduling scheme thatoptimizing the coded video transmission overmultipath wireless multimedia sensor networks interms of received video distortion and power efficiencyenhances the security aspects of the underlyingsystem.When the aggregate transmission rateavailable at the network cannot support the requiredtransmission rate,the scheduling algorithm can selectivelydrop combinations of video packets prior totransmission to adapt the rate of the sender to thelimitations of the wireless channel capacity.Twoscheduling algorithms are proposed.The Baselinescheme utilizes a novel distortion prediction modeland decides upon which packet can be dropped priorto transmission based on the packet’s impact on thevideo distortion.In addition to the bandwidthlimitations,the Power aware packet scheduling is an extension of the Baseline capable of estimating thepower that will be consumed by each node during thetransmission;hence it can control the power consumptionby selectively drop packets of low importanceto the decoded video.Simulation results indicatethe efficiency of the proposed scheduling schemein terms of received video distortion(PSNR)andpower consumption.
文摘This paper,resents a system called Athlos2,which implements strong access control for athletic events, enhancing the safety feeling of event spectators. Athlos2 integrates intelligent biometric access control systems and smart cards,under a protocol that complies ith the specification of the Liberty Alliance project for federated identities.A pilot version of Athlos2 was deployed and tested in terms of acceptability,information security and performance.
文摘It is with great pleasure that I am serving as a vip Editor for special issues of the CHINA COMMUNICATIONS JOURNAL on Communications and Information Security in Feb.and June,2007. The goal of these issues is to present the direction that the field has been taking in the last 3-5 years,introduce new
