數位廣播服務中，當使用者處於收訊較差、訊號衰弱或建築物的干擾時，收看數位廣播服務的使用者，會遭遇到訊號干擾或頻道中斷。訊號干擾會造成廣播封包掉落，導致廣播畫面播放不順暢及畫面出現馬賽克。頻道中斷則會造成廣播節目異常終止，會嚴重影響到收看數位廣播服務使用者的觀看品質(QoE)。目前已有一些方法，提出利用重傳機制，當廣播服務的使用者遭遇到訊號干擾或訊號中斷時，透過同儕網路，把缺少的廣播封包傳送回來。但他們都沒有協同同儕網路的使用者，所以會影響到廣播串流的可用性及搜尋時間。為了提高廣播封包的可用性，存太多份廣播封包會造成低使用率，存太少份廣播封包會造成低可用性。所以協同同儕網路中的廣播服務使用者，來分擔廣播服務使用者的負擔，在同儕網路中是非常重要的。在這篇論文中我們有提出，分擔同儕網路中使用者的負擔及在最短的收尋時間內，透過重傳機制把遺失或損毁的封包傳送回來。最後的實驗結果證明，我們提出的方法，可以在很短的收尋時間及很低的訊息量的情況下，有效分擔同儕網路中廣播使用者的負擔及提高廣播串流的可用性來維持廣播服務使用者的觀看品質。

Digital multimedia broadcasting services require resiliency against intermittent connectivity and signal loss when the end user is suffering from building penetration loss or fading conditions. Existing approaches use peer-to-peer schemes to repair loss packets via peer-to-peer networks. However, they ignore coordinating peers in peer-to-peer networks, this can have an effect on chunk availability and control messages overhead. Fewer replicas can lead to lower availability and more replicas may waste space in low utility environment. So, coordinating peers to distribute peer’s loading is very important in peer-to-peer streaming systems. In this thesis, we propose a novel approach that considers load distribution in structured peer-to-peer networks and repairing loss packets in short lookup latency. Performance evaluation results show that our proposed method can achieve load sharing and increase chunk availability, shorten lookup latency with low control messages overhead for the whole peer-to-peer networks.

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