Research On Multimedia Complex Transmission In EPA-Based Network Control System

The continues integration of industry information and automation urges the multimedia complex transmission in NCS(Network Control System). In order to realize the multimedia complex transmission in EPA-Based NCS, and reconcile the conflicts of control data and multimedia data, this thesis carries out the following works.1. Analysis of four basic key questions of the subject. For the first question of how to access multimedia device to EPA, this paper designs and develops a kind of EPA-access card through IP learning; for how to describe the model and transmission needs, this paper highlights a block-stream model for multimedia data; for how to handle the relationship of control data and multimedia data, this paper proposes the basic scheduling principles of complex transmission; and for different complex transmission scenario, this paper divides the static and dynamic complex transmission way according to different characteristics.2. Proposal of an EPA network resources pre-allocating static complex transmission algorithm for static complex transmission way——Determine the EPA scheduling parameters during the network design phase, plan the macro cycle width by the constraints of the smallest allowable transmission delay of control data and the delay jitter's uncertain factor of stable block-stream, then limit the time slice of each device with the target of fully using the bandwidth. The validation of this algorithm is verified through the application of video complex transmission in the NCS based on EPA and the delay test of this system further.3. Design of a feedback based EPA local time-domain dynamic complex transmission scheme for dynamic complex transmission way——By Dividing a kind of "multimedia dynamic scheduling period " from the periodic data communication time in EPA macro cycle, and feedback the information of the current network usage, the multimedia data's transmission delay and delay jitter, and the multimedia data's packet loss rate, through the heartbeat packet. And these parameters are handled by a certain weighting algorithm, to adjust the encoding rate in real time. This scheme can be achieved through four block-stream transmission scheduling services, and the support or improvement of the VBR(Variable Bit-rate) technology and EPA configuration technology. The feasibility of this scheme is demonstrated through theoretical analysis.