| Summary: | 碩士 === 國立中央大學 === 資訊工程研究所 === 93 === With the rapid development of wireless network technologies, there are more and more heterogeneous wireless networks. High bandwidth of wireless heterogeneous networks make possible more and more media streaming services provided in heterogeneous wireless networks, such as the Voice over IP (VoIP), the video conference and the Video on Demand (VoD) and so on. But, media streaming services are fragile and affected easily by varied network qualities. And the following are the major problems to be solved. First, there are very different end-to-end delays in different wireless networks; it causes the offset of frame arrival times when a mobile node roams in heterogeneous wireless networks. Users will be conscious of frame dropped if the offset is too large. Second, the vertical handoff delay is too long and the mobile node may lose many packets in the duration. Users would feel the media streaming services suspended during vertical handoffs.
The thesis proposes a Media Streaming Synchronization System (MSSS) which adopts a synchronization estimating algorithm (SEA) to estimate the sequence number of media frame which mobile node should request the media streaming server in different access networks. In other words, the MSSS can synchronize the media streams and then reduce the offset of frame arrival interval. In order to reduce packet loss during vertical handoff, the MSSS receives media streams from another interface before vertical handoff. Because of receiving media streams from multiple interfaces during vertical handoff, there are redundant frames received. The MSSS also reduce the redundant frames during vertical handoff effectively by SEA.
In the thesis, the simulations show that the proposed MSSS could reduce 97.12% the offset of frame arrival time. At the part of packet loss during vertical handoffs, the MSSS can reduce approximately 72.69% packet loss and 78.18% redundant frames in average. Hence, the proposed MSSS could reduce the effect of varied network qualities on media streaming services.
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