This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile muhimedia communication, which simultaneously adapted to both the varying channel characteristics and the qual...This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile muhimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service （QoS） of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.展开更多
Spar platforms could be subject to vortex-induced-motions(VIM) in certain current conditions.Lockin is a phenomenon which occurs in a range of reduced velocities in VIM.In this paper,a new concept of spar platform cal...Spar platforms could be subject to vortex-induced-motions(VIM) in certain current conditions.Lockin is a phenomenon which occurs in a range of reduced velocities in VIM.In this paper,a new concept of spar platform called cell-truss spar is studied using both computational fluid dynamics(CFD) and model test to investigate the VIM of the spar under different reduced velocities.The unique configuration of the cell-truss spar is carefully considered,and the unsteady flow around the spar is calculated and visualized in CFD simulations.A physical model with a scale ratio of 1:100 of the cell-truss spar is fabricated,and model tests are carried out in the current-generating ocean engineering basin.Many important parameters in VIM of the cell-truss spar are obtained,the occurrence of lock-in phenomenon is successfully simulated,and the mechanism and rules of lock-in are analyzed.展开更多
基金Supported by the National High Technology Research and Development Programme of China (No. 2001AA121031 )the National Natural Science Foundation of China (No. 60072028)
文摘This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile muhimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service （QoS） of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.
基金the National High Technology Research and Development Program (863) of China(No. 2006AA09A107)the Key Fundamental Research Project of Science and Technology Commission of Shanghai Municipality (No. 07XD14018)
文摘Spar platforms could be subject to vortex-induced-motions(VIM) in certain current conditions.Lockin is a phenomenon which occurs in a range of reduced velocities in VIM.In this paper,a new concept of spar platform called cell-truss spar is studied using both computational fluid dynamics(CFD) and model test to investigate the VIM of the spar under different reduced velocities.The unique configuration of the cell-truss spar is carefully considered,and the unsteady flow around the spar is calculated and visualized in CFD simulations.A physical model with a scale ratio of 1:100 of the cell-truss spar is fabricated,and model tests are carried out in the current-generating ocean engineering basin.Many important parameters in VIM of the cell-truss spar are obtained,the occurrence of lock-in phenomenon is successfully simulated,and the mechanism and rules of lock-in are analyzed.
