在行動隨機網路(mobile ad hoc networks, MANETs)的範疇中，以往的群播機制(quality-of-service, QoS)主要是利用建立滿足頻寬要求路徑的方式，以達成保證連線的服務品質。文獻指出，群播機制若是只考慮one-hop的鄰居資訊，則會因為隱匿終端機所產生的訊號干擾，而造成頻寬無法滿足要求。群播機制的問題主要有隱藏路線問題與隱藏群播路由問題。隱藏路由問題是當有新的頻寬要求被允許時，新的資料流與two-hop的鄰居資料流會相互干擾，造成兩者共同鄰居的頻寬無法滿足要求；隱藏群播路由問題是當有多個距離相近的資料流的頻寬要求被允許時，造成相互訊號干擾而無法同時滿足所有頻寬需求。為了同時解決上述兩個頻寬違反要求的問題，目前已有文獻提出群播樹機制(Multicast)。群播樹機制主要是一個來源端傳送資料給多個目的地端。但是在建置群播樹時，廣播過多的控制封包，容易造成節點消耗過多不必要的資源，使得頻寬出現浪費。因此，本研究提出同時以two-hop鄰居資訊之表格與較少量的訊息交換以粗估頻寬需求，並以共用的概念選擇能夠集結較多資料流的中繼節點作為群播樹的成員。研究結果顯示，經由NS-2的模擬，本研究提出的演算法能夠維持群播樹良好的完整度與封包輸出量，同時兼顧節省大量的控制訊號數量與能量消耗。

Previous quality-of-service (QoS) multicasting/routing algorithms in mobile ad hoc networks (MANETs) resolved bandwidth-contented routes for QoS applications. However, without considering the two-hop neighborhood, they suffer two bandwidth-violation problems, namely, the hidden route problem (HRP) and the hidden multicast route problem (HMRP). HRP may occur when a new flow is allowed and the unaware bandwidth requirement of nodes in the two-hop neighborhood has existed. HMRP may occur when bandwidth requirements of multiple new adjacent flows are allowed currently. Although the bandwidth-satisfied multicast tree in MANETs to solve both two bandwidth violation problems has been proposed, it floods quantities of control messages to collect information of all nodes for establishing a multicast tree. Therefore, we propose a novel algorithm to construct a multicast tree based both on the information in two-hop neighborhood tables to roughly estimate the bandwidth requirement with fewer control messages, and on a relay-sharing concept to choose a relay covering as many flows as possible. The proposed algorithm avoids two bandwidth violation problems and reduces the quantity of control messages. The NS-2 simulation results show that our algorithm not only obtains the high integrity of multicast trees and the high throughput, but also significantly reduces the amount of control messages and the power consumption.

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