Non-Line-of-Sight(NLOS)Ultraviolet(UV)communication uses the atmosphere as a propagation medium.As the communication range increases,turbulence becomes a significant atmospheric process that affects the propagation of...Non-Line-of-Sight(NLOS)Ultraviolet(UV)communication uses the atmosphere as a propagation medium.As the communication range increases,turbulence becomes a significant atmospheric process that affects the propagation of optical waves.This paper presents a more accurate NLOS channel model by considering turbulence-induced Scintillation Attenuation(SA).Then,the Bit Error Rate(BER)during turbulence of the NLOS UV communication system with On-Off Keying(OOK)modulation and Maximum Likelihood(ML)detection is analysed and compared with that in free space without turbulence.The BER dependence is also analysed for different factors,including the refractive index structure parameter,transceiver range,pointing angles,transmitted power,and data rate.展开更多
In this letter, a novel method based on Temporal and Spatial Prediction (TSP) to detecl all-zero DC.'T coefficients based on temporal and .spatial prediction between neighboring blocks is proposed. The presented a...In this letter, a novel method based on Temporal and Spatial Prediction (TSP) to detecl all-zero DC.'T coefficients based on temporal and .spatial prediction between neighboring blocks is proposed. The presented algorithm uses the knowledge of all-zero block distribution in the previous frame combined with the Sum of Absolute Difference (S.AD) of the corresponding macroblock as a. criterion. The algorithm almost needs no additional computation, and it. shows an excellent overall detection performance in simulations.展开更多
Robust video streaming through high error prone wireless channel has attracted much attention. In this paper the authors introduce an effective algorithm by joining the Unequal Error Protection ability of the channel ...Robust video streaming through high error prone wireless channel has attracted much attention. In this paper the authors introduce an effective algorithm by joining the Unequal Error Protection ability of the channel multiplexing protocol H.223 Annex D, and the new H.263++ Annex V Data Partition together. Based on the optimal trade off of these two technologies, the Joint Source and Channel Coding algorithm can result in stronger error resilience. The simulation results have shown its superiority against separate coding mode and some Unequal Error Protection mode under recommended wireless channel error patterns.展开更多
A novel error resilient method based on Essential Information Aggregation (EIA) technique is proposed for robust wireless transmission of intra coded video frames. This method modifies the original video stream struct...A novel error resilient method based on Essential Information Aggregation (EIA) technique is proposed for robust wireless transmission of intra coded video frames. This method modifies the original video stream structure so as to mitigate the effect of decoding loss of synchronization within a video frame, for which Macro Block Aligned (MBA) error detection method is accompanied to be developed. Experiments on an Additive White Gaussian Noise (AWGN) wireless simulation platform and H.263+ baseline video codec show that it can obtain better subjective and objective image quality than existing error resilience approaches.展开更多
The emergence of third generation mobile system (3G) makes video transmission in wireless environment possible, and the latest 3GPP/3GPP2 standards require 3G terminals support H.264/AVC. Due to high packet loss rate ...The emergence of third generation mobile system (3G) makes video transmission in wireless environment possible, and the latest 3GPP/3GPP2 standards require 3G terminals support H.264/AVC. Due to high packet loss rate in wireless envi- ronment, error resilience for 3G terminals is necessary. Moreover, because of the hardware restrictions, 3G mobile terminals support only part of H.264/AVC error resilience tool. This paper analyzes various error resilience tools and their functions, and presents 2 error resilience strategies for 3G mobile streaming video services and mobile conversational services. Performances of the proposed error resilience strategies were tested using off-line common test conditions. Experiments showed that the proposed error resilience strategies can yield reasonably satisfactory results.展开更多
基金supported by the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China
文摘Non-Line-of-Sight(NLOS)Ultraviolet(UV)communication uses the atmosphere as a propagation medium.As the communication range increases,turbulence becomes a significant atmospheric process that affects the propagation of optical waves.This paper presents a more accurate NLOS channel model by considering turbulence-induced Scintillation Attenuation(SA).Then,the Bit Error Rate(BER)during turbulence of the NLOS UV communication system with On-Off Keying(OOK)modulation and Maximum Likelihood(ML)detection is analysed and compared with that in free space without turbulence.The BER dependence is also analysed for different factors,including the refractive index structure parameter,transceiver range,pointing angles,transmitted power,and data rate.
文摘In this letter, a novel method based on Temporal and Spatial Prediction (TSP) to detecl all-zero DC.'T coefficients based on temporal and .spatial prediction between neighboring blocks is proposed. The presented algorithm uses the knowledge of all-zero block distribution in the previous frame combined with the Sum of Absolute Difference (S.AD) of the corresponding macroblock as a. criterion. The algorithm almost needs no additional computation, and it. shows an excellent overall detection performance in simulations.
文摘Robust video streaming through high error prone wireless channel has attracted much attention. In this paper the authors introduce an effective algorithm by joining the Unequal Error Protection ability of the channel multiplexing protocol H.223 Annex D, and the new H.263++ Annex V Data Partition together. Based on the optimal trade off of these two technologies, the Joint Source and Channel Coding algorithm can result in stronger error resilience. The simulation results have shown its superiority against separate coding mode and some Unequal Error Protection mode under recommended wireless channel error patterns.
文摘A novel error resilient method based on Essential Information Aggregation (EIA) technique is proposed for robust wireless transmission of intra coded video frames. This method modifies the original video stream structure so as to mitigate the effect of decoding loss of synchronization within a video frame, for which Macro Block Aligned (MBA) error detection method is accompanied to be developed. Experiments on an Additive White Gaussian Noise (AWGN) wireless simulation platform and H.263+ baseline video codec show that it can obtain better subjective and objective image quality than existing error resilience approaches.
基金Project supported by the National Natural Science Foundation of China (Nos. 60473106 and 60333010), China Ministry of Education(No. 20030335064), and China Ministry of Science and Technology(No. 2003AA4Z1020)
文摘The emergence of third generation mobile system (3G) makes video transmission in wireless environment possible, and the latest 3GPP/3GPP2 standards require 3G terminals support H.264/AVC. Due to high packet loss rate in wireless envi- ronment, error resilience for 3G terminals is necessary. Moreover, because of the hardware restrictions, 3G mobile terminals support only part of H.264/AVC error resilience tool. This paper analyzes various error resilience tools and their functions, and presents 2 error resilience strategies for 3G mobile streaming video services and mobile conversational services. Performances of the proposed error resilience strategies were tested using off-line common test conditions. Experiments showed that the proposed error resilience strategies can yield reasonably satisfactory results.
