Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Cross-Layer Techniques for Adaptive Video Streaming over Wireless Networks | EURASIP Journal on Applied Signal Processing 2005 2 220-228 2005 Hindawi Publishing Corporation Cross-Layer Techniques for Adaptive Video Streaming over Wireless Networks Yufeng Shan Department of Electrical Engineering and Computer Sciences University of California Berkeley CA 94720 USA Email yfshan@ Received 16 July 2003 Revised 9 June 2004 Real-time streaming media over wireless networks is a challenging proposition due to the characteristics of video data and wireless channels. In this paper we propose a set of cross-layer techniques for adaptive real-time video streaming over wireless networks. The adaptation is done with respect to both channel and data. The proposed novel packetization scheme constructs the application layer packet in such a way that it is decomposed exactly into an integer number of equal-sized radio link protocol RLP packets. FEC codes are applied within an application packet at the RLP packet level rather than across different application packets and thus reduce delay at the receiver. A priority-based ARQ together with a scheduling algorithm is applied at the application layer to retransmit only the corrupted RLP packets within an application layer packet. Our approach combines the flexibility and programmability of application layer adaptations with low delay and bandwidth efficiency of link layer techniques. Socket-level simulations are presented to verify the effectiveness of our approach. Keywords and phrases video streaming wireless cross layer multimedia. 1. INTRODUCTION Real-time streaming media over wireless networks such as live video streaming of a football match to a wireless terminal is becoming an increasingly important application. In order to be real time the end-to-end delay of the delivery system should be minimized given a certain quality requirement. Traditional streaming systems http windows windowsmedia http use a large receiver buffer to absorb channel variation and to
