The Study On Video Transmission Technology In Wireless Multi-hop Environment

Recently, with the extraordinarily rapid development of wireless communication, the demand for voice, video and other multimedia communications is increasingly strong. Multi-hop access to network, we can shorten the distance between nodes to improve network coverage and achieve larger network capacity. Therefore, video transmission in wireless multi-hop environment has become a hot spot of current research.Due to the serious conflict, user inter-symbol interference and fading in wireless network, traditional OSI seven layer protocol architecture has the characters of non-optimal and non-flexibility, therefore we can adopt cross-layer design approach to meet the QoS support for a variety of services and achieve maximum capacity of the network. Unlike other multi-hop environment, wireless body area network (WBAN) has limited transmit power, very limited battery energy, and severe time-varying and complex modeling channel condition due to the existence and movement of human body, so it is necessary to conduct research for cross-layer optimized video transmission in WBAN environment.This paper first studies current cross-layer modeling methods in wireless network, then after full study of the cross-layer design model in wireless Mesh network and multi-hop cellular network, combined with consideration of the characters of WBAN, we propose a model updating separately. Next, based on detailed analysis of the characteristics of WBAN channel, appropriate Markov model has been proposed. Then we study the performance of the H.264 stream in a single hop and multi-hop WBAN channel, later a design cross-layer design and scheduling solution has been proposed to optimize the transmission of H.264 stream.This paper has designed the related hardware platform, including scheme selection, chip selection and curcuit module design, then we implement and optimize H.264 video codec on ADSP-BF561 platform. Finally, this paper proposes a consideration of further optimization of system framework for video transmission and makes some instructive attempts to improve the frame structure and design of energy efficient routing protocols.