行動隨意式網路(MANET)是一種具有高度動態拓撲結構的網路。 每一個行動隨意式網路由一組移動節點(Node)組成， 彼此之間互相支援轉送封包可以不依靠基地台建構成Intranet。 此種網路中，因節點移動之緣故，連線不穩定、頻寬較窄， 錯誤率亦較高。傳統的TCP傳輸協定在行動隨意式網路上 的效能不免遭受重創。 傳統的TCP在封包遺失時，只能從傳送端進行重傳， 而行動隨意式網路傳輸品質極不穩定，常常重送多次 才可到達目的地，導致要耗費極長的時間才能將封包 送達目的地，然而，在行動隨意式網路中，大量傳輸 資料的需求並不大，反而是封包的快速送達更為重要， 因此加速封包的送達成為比增大傳送量更為重要的目標。 為了使封包較快送達目的地端，我們提出了Hop-by-Hop TCP 的方法，使每個節點使用當地重傳以保證封包成功的傳到 下一個節點，遺失的封包不必重新由傳送端重傳， 能更快反應封包遺失，並且提昇傳輸可靠度， 使封包在高遺失率的情形之下能順利且較為快速的送達目的地端。 我們利用NS-2網路模擬器進行實驗，驗證我們的機制， 實驗在不同的拓樸及負載等參數下進行，觀察傳輸成功率及 封包傳輸時間，以及公平性。實驗結果指出， 本方法在網路環境不穩定時吞吐量能有25.7%以上的提昇， 而延遲時間也能降低25%，亦有相當好的公平性。
A Mobile Ad hoc Network (MANET) MANET is composed of a group of mobile computing devices (nodes) that are equipped with Wireless LAN (WLAN) capability. Nodes can transmit packets to each other to construct Intranet without any base station. In an MANET environment, the communication links are unstable due to various reasons. Error rate is higher and bandwidth is smaller than fixed networks. Running regular TCP protocol on MANET will suffer from serious performance degradation in MANET. To handle packet lost, regular TCP can only retransmit lost packets from the source. However, when error rate is high, several retransmissions may be needed to transmit a packet to its destination successfully. As a result, the effective bandwidth is much lower and the average time to transmit a packet will be much longer. Considering that most applications on MANET prefer shorter transmission time to higher bandwidth, this thesis proposes Hop-by-Hop TCP protocol aiming to accelerate the transmission of packets. Hop-by-Hop TCP makes every intermediate node in the transmission path running a local TCP to guarantee the transmission of each packet on each link. The retransmission of a lost packet is right at the transmitting end of the link where the packet is lost. It doesn't need to retransmit a lost packet from its source node. It takes less time in average to transmit a packet to its destination in a high error rate environment. We evaluate the performance of our approach by simulation using NS-2 simulator. Our experiments show that our proposed protocol outperforms TCP Reno by 25.7% in throughput and 25% reduction in average transmission time. The fairness requirement is also achieved while our proposed protocol coexists with other major TCP variants.