在感測網路(Sensor Network)上，每一個感測節點與網點狀無線網路(Ad-Hoc Network)的節點相較，其硬體資源有著嚴苛的限制。而感測節點所擁有的電能多寡，則是影響網路是否可長時間持續運作的重要關鍵。當網路上的兩節點彼此間要互相溝通傳遞資料時，往往是透過廣播(Broadcast)路徑搜尋訊息的方式來找出到達彼此間之路徑。在網點狀無線網路需求向量繞路(Ad-hoc On-Demand Distance Vector Routing,AODV)中是以泛流式(Flooding)廣播進行路徑搜尋，這樣的方式適用在網路拓蹼變動速度較快且不考慮節點電能限制的無線網路環境。
　
　　為了降低感測網路上路徑搜尋時的電能負擔，本論文中提出了一個以AODV為基礎並改善路徑搜尋廣播以及路徑建立方式的省電多重路徑搜尋協定。在此搜尋協定中，節點以被動的方式取得其鄰近節點資訊，而於廣播時選擇不須廣播的節點來減少訊息廣播，並以電能負擔較低的單一傳送(Unicast)訊息確認兩節點間的雙向路徑。在路徑建立的方法上，則是在節點上建立多重路徑以提高資料傳輸時的可靠度並避免不必要的路徑修復動作。
　
　　本論文中，最後以網路模擬實驗來進行驗證，與其它路徑搜尋方法相較，我們的方法將可以有效降低路徑廣播搜尋時的電能負擔。

　　In the sensor network, nodes have more hardware limitation than the nodes in the Ad-Hoc Network. The power of node is crucial to the lifetime of the sensor network. When two nodes want to communicate each other, they always have to find a path between them by broadcasting route search message. Traditional Ad-hoc On-Demand Distance Vector Routing Protocol(AODV) broadcasts messages using flooding method, howerver, flooding is suitable for a dynamic network topology enviroment, and is prone to more power consumption and message collision.
　
　　In this paper, we propose a Power Efficient Multipath Path Discovery(PEMD) protocol for sensor network. In PEMD, sensor nodes collect their neighbor information in a passive manner, and then a node which will broadcast can select the unbroadcast neighbors to avoid unnecessary broadcast operation for conserving node's power. The PEMD uses unicast method to certify bidirectional route between two nodes and allows nodes to create multipath route entry during path discovery phase.
　
　　The performance of PEMD is compared with AODV, Flossiping and SARP, simulation results show that the proposed PEMD decreases the power consumptions, reduces the message collisions, and has good path discovery success rate in static or slowly changing wireless sensor network.

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