An opportunistic automatic repeat request （ARQ） scheme was developed to support high-quality video transmission over cooperative decode-forward networks. The opportunistic ARQ is implemented in the form of distribut...An opportunistic automatic repeat request （ARQ） scheme was developed to support high-quality video transmission over cooperative decode-forward networks. The opportunistic ARQ is implemented in the form of distributed space-time block codes （STBCs） and the desired STBC for a certain channel state is de- termined by the diversity-multiplexing tradeoff principle. With good channel states, the source and relay may jointly retransmit the lost video packets using high-rate low-diversity codes while with bad channel states they will retransmit the lost video packets using low-rate high-diversity codes. Furthermore, an adaptive packet dropping mechanism was introduced by considering the delay constraint and layer dependency characteristics of scalable video streaming. Test results show that the scheme significantly improves the throughput and video quality compared with other schemes. Tests also indicate that the source-relay link condition plays an important role in affecting the scheme performance.展开更多
Multimedia data have become popularly transmitted content in opportunistic networks. A large amount of video data easily leads to a low delivery ratio. Breaking up these big data into small pieces or fragments is a re...Multimedia data have become popularly transmitted content in opportunistic networks. A large amount of video data easily leads to a low delivery ratio. Breaking up these big data into small pieces or fragments is a reasonable option. The size of the fragments is critical to transmission efficiency and should be adaptable to the communication capability of a network. We propose a novel communication capacity calculation model of opportunistic network based on the classical random direction mobile model, define the restrain facts model of overhead, and present an optimal fragment size algorithm. We also design and evaluate the methods and algorithms with video data fragments disseminated in a simulated environment. Experiment results verified the effectiveness of the network capability and the optimal fragment methods.展开更多
基金Supported by the National Natural Science Foundation of China(No. 60772055)the Scientific and Technological Innovation Nurture Funds of MOE, China (No. 707005)
文摘An opportunistic automatic repeat request （ARQ） scheme was developed to support high-quality video transmission over cooperative decode-forward networks. The opportunistic ARQ is implemented in the form of distributed space-time block codes （STBCs） and the desired STBC for a certain channel state is de- termined by the diversity-multiplexing tradeoff principle. With good channel states, the source and relay may jointly retransmit the lost video packets using high-rate low-diversity codes while with bad channel states they will retransmit the lost video packets using low-rate high-diversity codes. Furthermore, an adaptive packet dropping mechanism was introduced by considering the delay constraint and layer dependency characteristics of scalable video streaming. Test results show that the scheme significantly improves the throughput and video quality compared with other schemes. Tests also indicate that the source-relay link condition plays an important role in affecting the scheme performance.
基金supported by the Shaanxi Natural Science Foundation Research Plan (No. 2015JQ6238)the China Scholarship Council+3 种基金the National Natural Science Foundation of China(Nos. 61373083 and 61402273)the Fundamental Research Funds for the Central Universities of China (No. GK201401002)the Program of Shaanxi Science and Technology Innovation Team of China (No. 2014KTC18)the 111 Programme of Introducing Talents of Discipline to Universities (No. B16031)
文摘Multimedia data have become popularly transmitted content in opportunistic networks. A large amount of video data easily leads to a low delivery ratio. Breaking up these big data into small pieces or fragments is a reasonable option. The size of the fragments is critical to transmission efficiency and should be adaptable to the communication capability of a network. We propose a novel communication capacity calculation model of opportunistic network based on the classical random direction mobile model, define the restrain facts model of overhead, and present an optimal fragment size algorithm. We also design and evaluate the methods and algorithms with video data fragments disseminated in a simulated environment. Experiment results verified the effectiveness of the network capability and the optimal fragment methods.
