Research And Implementation On QoS Of Video Real-time Transmission Based On AP

In recent years, with the rapid development of 4G techology, the focus of mobile data services transfers from voice, image to audio and video multimedia data gradually. In high density scenarios, WLAN is a very good supplement to 4G and can be mixed with LTE. However, CSMA/CA is the mechanism that adopts for the competition of channel resource. The intensive distributed AP will cause interference for both co-channel and inter-channel, which has a negative effect on the QoS of WLAN streaming. So, how to dynamically adjust the streaming transmission strategy and according to wireless network status and provides acceptable QoS in complicated wireless environment has become a hot topic.The traditional QoS technologies evaluate the congetion condition of networks based on the feedback from the receiver. The congestion status may have changed when the sender receives the feedback. It causes the inaccuracy and low resource utilization in real-time QoS adjustment. Studying on the QoS technology of streaming media transmission is mainly in NS2 platform. Some of the important parameters such as the AP hardware queue and the specified packet transmission can not be obtained in the actual system because the chip manufacturers do not open the interface. In addition, there is no simulation framework of open source real-time streaming media system for all video coding formats, which brings inconvenience for simulation test of real-time video transmission QoS. Therefore, the paper chooses actual network card RT3070 as study object, proposed the method of obtaining the AP queue information and implements the monitoring module of network status in AP driver. MyEval AVC-RA simulation framework based on MyEvalSVC and Evalvid-RA streaming is designed for real-time streaming WLAN of H.264/AVC video files. And the proposed rate control algorithm is verified on the simulation platform. Finally, in order to validate the algorithm, a complete real-time video transmission system is built on the S3C6410 processor platform. The hardware system uses the RT3070 network card to implement the software AP. The test results in the simulation framework and the actual system show that the rate control based on AP has better performance in decoding frame rate, PSNR and so on.