在無線感測以及隨意網路中，許多地理繞徑 (Geographic Routing) 的演算法已經被證明了擁有傑出的效能。這些繞徑演算法需要感測節點擁有地利位置的資訊，並且使用位置資訊以貪婪演算法繞送封包至目的地。地理位置資訊可以藉由全球定位系統(GPS)裝置獲得。然而，在一個廣大的無線感測網路中，因為感測節點的體積大小、成本以及電力的限制，因此，替每個無線感測節點裝設全球定位系統裝置並不適合。在此篇論文中，我們提出了一個分散式的協定來建立以跳步計數 (hop count) 為基礎的虛擬座標系統，此系統可以有效率的支援地理繞徑演算法，而不需要用到全球定位系統裝置。我們的協定簡單、容易實做，而且非常適合廣大的無線感測網路。藉由我們的模擬結果，我們的協定跟之前的文獻相比，有較佳的封包遞送比率 (packet delivery ratio)、較短的傳送封包時間、及較少的通訊負荷。 Many geographic routing algorithms have been proven to provide great performance in wireless sensor and ad hoc networks. These algorithms need nodes to have location information, and use these locations to route greedily toward the destination. Location information can be acquired by GPS device. However, to equip a GPS device to each sensor node in a large wireless sensor network is not applicable because of size, cost, and power constraints of the sensor nodes. In this thesis, we proposed a distributed protocol to build a logical coordinates system based on hop counts which can support geographic routing efficiently without the GPS device. Our protocol is simple and easy to implement, and suitable for large scale wireless sensor networks. The simulation results show that our proposed protocol has the superior performances in packet delivery ratio, average hop counts among nodes, and communication overhead to previous work.
