基於IEEE 802.21之動態調整群播影像的畫面更新率以達成無縫式換手之研究

Abstract

The Internet multimedia applications are more and more popular at the present age. A lot of applications become parts of our life such as online game, network TV, video phone and etc. In these services, the network transmission arrive rate will affect the video streaming quality directly. Multimedia service will be delayed or interrupted by end-to-end time delay, jitter, frame error, and packet loss. However, these facts would also happen during handover. There are many kinds of wireless, from IEEE 802 families to UMTS network, even more 3GPP LTE. These networks enhance the ability of multimedia services as good as possible. The user or application will choose the best network from signal strength, price, QoS, network coverage, and so on. When the mobile device moves, the handover between different networks will happen frequently. In order to perform seamless handover between heterogeneous wireless network, IEEE group propose the IEEE 802.21 standard. IEEE 802.21 defines a middleware function to make handover smoothly, which is called Media Independent Handover (MIH) function. When a mobile host (MH) tries to handover into another network, the media streaming must be interrupted until the new connection is established to new point-of-attachment (POA) or base station (BS). We propose a novel buffer management and frame rate control to provide enough frame packets for streaming. By this method, the multimedia service can make handover seamlessly between heterogeneous wireless networks. In order to satisfy all application during handover, we add a buffer in MIH. We also use Service Specific Layer (SSL) to bridge the MIH and Upper applications. Therefore, the different applications can fit different buffer management mechanism according MIH. Then we expound the procedure of heterogeneous handover, and talk about the effect of video transmission during handover in frame-based viewpoint. Finally, we discuss how to dynamically adjust buffer to reduce the probability of video disruption. With the development of communication technology, we can use mobile phone and PDA to access internet. Therefore, network handover is hard to avoid. Multimedia streaming services by network transmitting are also growing fast. Video and audio data have become the most data in network packets. This research gives a solution to reduce influence of handover between heterogeneous networks, especially in streaming transmission. By this method, the quality of streaming service will be better.