近年來，無線網路的普及帶給我們許多的便利，而其中的合作式網路(cooperative networks)也是當中一個重要的研究議題，它充分利用無線頻道廣播性質和空間的分集(spatial diversity)， 從而實現了改善系統的能力和延誤，但在某些情況下，一直藉由合作式的機制而維持通訊的連線，不僅增加傳送的不可靠性，也有可能降低效能，尤其是在MANET這種節點時常變動的環境，在這篇論文提出一個以合作式網路為基礎的MAC協定，藉由一些MAC 層獲得的資訊來改變路由，我們能增加一個relay結點在一條不可靠的鏈結或是將封包送到更接近終點的節點以增加可靠度和吞吐量(throughput)。模擬的結果顯示我們比之前的方法有更好的效能。

Cooperative retransmission scheme is used to reduce the probability of the packets retransmission from sender to receiver and result in increasing network throughput. In this paper, we propose a cooperative MAC protocol to improve the network performance in mobile ad hoc networks. In the proposed protocol, we can add an extra relay node between sender and receiver if the sender cannot send frames to the receiver reliably. On the other hand, a receiver can be bypassed if transmission frames can be received by next two-hop receivers. Therefore, our protocol cannot only improve the transmission reliability but reduce the routing delay time. Simulation results show that the performance of our protocol is better than previous work.

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