在無線感測網路(Wireless Sensor Networks, WSNs)中，資料收集(Data Collection)是一個重要的研究議題。本論文考慮因地形因素限制，監控場景中存在許多不連續監控子區域，而每個區域已佈建數個固定式感測器感測資料。資料傳輸方式若以固定式感測器多步代傳(multi-hop)至收集站，則監控場景內需額外佈建大量的固定式感測器，造成部署硬體成本過高。此外，以多步代傳進行資料收集時，將使感測器耗電量不均，進而縮短網路生命期。有鑒於此，本論文利用移動式資料收集器(Data Mule, DM)進行資料收集任務，以解決部署成本過高及感測器耗電量不均的問題。此外，為了縮短收集器的資料收集路徑，以期降低資料回傳時間，本論文選擇數個感測器做為資料轉傳節點，使收集器僅需與資料轉傳節點通訊，即能有效網路內所有感測資料。不同於以往研究，本論文設計Energy-Balanced Patrolling機制使感測器根據每回合自身及其鄰居的剩餘電量及儲存空間，動態地決定自身是否擔任資料轉傳節點，藉此平衡感測器間的電量，進而延長網路生命週期。此外，本論文亦根據不同區域的資料量，可選擇不同數量的轉傳節點，讓轉傳節點能儲存並轉傳更多感測資料，以避免感測器暫存器溢滿並增加網路資料傳輸量(throughput)。 In wireless sensor networks, data collection is one of the key issues needed to be addressed. This paper takes into consideration the limitation of terrain to develop an efficient data collection mechanism for many disconnected monitoring areas. Traditionally, each monitoring area has been allocated amount of static sensors which are responsible for relaying data to the sink node via multi-hop technique. However, it introduces the high hardware cost and energy-unbalanced problems, reducing the network lifetime. To cope with above-mentioned problems, this paper uses the data mule (DM) to collect sensory. In this paper, some sensors will function as the forwarders which aim to collect the sensory and then relay to DM for conserving the energies of the other sensors. Moreover, to further prolong the network lifetime, this paper allows that the sensor can locally determine be a forwarder in each round according to its remaining energy and remaining buffer capacity. Furthermore, the proposed data collection mechanism allows that each monitoring area has multiple forwarders to relay data to DM, and thus the network throughput can be improved.
