無線感測網路已經被廣泛地應用在嚴苛環境中的監控工作，為了可以在任何時間地點都可以存取收集到資料，每一個配有監控配備的節點必須把監控到的數據資料傳送到網路中所有其他的節點。傳送資料所需要消耗的電量多寡會直接地影響到節點的生命維持時間，因此在無線感測網路中，如何減少資料的傳送次數是一個很重要的議題。本論文提出一個分散式的排程網路編碼來使得廣播資料更有效率，在此方法中，每個節點首先會收集兩步鄰居內的資訊，並用此資訊決定一個能使傳送次數最少的策略來傳送編碼過後的資料。根據這個策略，每當收到一個新資料時，可以決定是否要廣播這個資料或者是不廣播來減少封包傳送的次數。我們所提出的方法可以應用在任何的廣播情境之中，例如單點廣播、多點廣播或者是全體廣播。本論文的模擬結果顯示我們所提出的方法，跟過去所提出之方法所比較起來，不僅可以有效地減少傳送次數，並且有很高的機率可以使得每個節點都可以還原出所有監控到的數據資料。

Wireless sensor networks (WSNs) have been widely used for surveillance in harsh environments. Each sensing node has to distribute its sensing data to all other nodes for ubiquitous data collection. The amount of battery energy consumed to transmit a packet to other nodes directly affects sensors’ lifetime and thus is considered as a critical issue in WSNs. In this thesis, we propose a scheduling network coding protocol to broadcast data more efficiently than previous network coding schemes. In our protocol, first, each node collects its neighbors’ information in two hops, and then it determines a local optimal encoding packet transmitting policy. According to this policy, each node decides whether to send out the encoding packet or do nothing to reduce the redundant transmissions when receiving a novel packet at the certain time. Our protocol can be applied to any broadcasting scenario, such as single-source broadcasting, multi-source broadcasting or all-to-all broadcasting. The simulation results show that our protocol not only reduces the number of broadcastings significantly compared to previous works, but also promises that each node in the network can recover all sensing data with a high probability.

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