隨著無線網路技術的百家爭鳴，網路使用者有了各式各樣的選擇，包含不同的頻寬、不同的網路涵蓋範圍以及不同的價格。而隨著這些網路的佈建與普及，越來越多的使用者端設備同時具有多種的網路介面，以提供使用者多樣化的選擇，甚至同時使用多種網路。這些同時使用多種網路的使用者稱為多重連線使用者(multihomed user)，而多種不同的網路形成的網路環境則稱為異質無線網路環境。新的無線網路科技如IEEE 802.11(Wi-Fi), IEEE 802.16(WiMAX)以及802.20(MBWA)開始能提供串流多媒體服務(media streaming services)，但若要在上述之異質網路環境中提供串流多媒體服務則仍有許多問題。首先，在使用串流多媒體服務時若遇上交遞(handoffs)將可能導致服務暫停或中斷；其次，不同種類的網路所能提供之服務品質及頻寬也大不相同，使用者在不同的網路間移動時，如何得到相同的服務品質也是一個議題。本論文針對前者提出了一個多重連線串流多媒體服務架構(Multihomed streaming media architecture)以提供使用者在某一網路交遞時不中斷的串流多媒體服務。當使用者某一網路在交遞時，透過多個網路提供使用者多個串流做為備援，可以讓使用者不因交遞時的網路服務中斷而導致串流多媒體服務中斷。然而經由不同網路傳立的多份串流可能會不同時抵達，所以本論文也提出一串流多媒體同步演算法來控制多份串流，使其同時抵達。而針對頻寬落差過大以及涵蓋範圍不足的問題，本論文提出使用隨意網路來延伸高頻寬網路的涵蓋範圍，並減少使用者更換IP的次數。 The emerging wireless network technologies have made it possible for the users to access to the Internet ubiquitously. And the variety of the wireless network technologies gives the users choices for prices, bandwidth and coverage and so on. These wireless networks can be accessed by the users simultaneously form a heterogeneous wireless network (HWN) environment. The wireless network technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (Wi-Max) and IEEE 802.20 (MBWA) have enabled the streaming media services, but the characteristics of HWN bring new challenges of providing them. Handoffs during delivering streaming media may pause or break the service. Coverage and bandwidth provide by different kind of networks are very different. It makes the provision of equal quality for mobile users ubiquitously difficult. For the former problem, the dissertation proposes to use the multihoming techniques during handoffs to ease the effect of delay, pause or termination of service delivery. Multicasting is utilized to provide multiple copies of streams to the user multihomed so that there will be backup streams for the user when specific network interface is handing off. Multiple streams delivering via different route may arrive at different time, so the dissertation proposed a streaming media synchronization algorithm to synchronize the streams to ensure the backup streams arrive in time. For the latter problem, the dissertation introduces ad hoc networks as interjacency to help to extend the service coverage and thus reduce the IP change rate.
