一個用於M2M通訊之有效節能的分群機制

Abstract

近年來由於物聯網的快速興起，帶動了M2M 及WSN 的研究熱潮。M2M 被廣泛應用於個人健康監測、智慧電網、智慧交通、智慧居家和環境監控等服務。在物聯網的應用中，許多裝置都是使用具有限制的電源供給、通信能力及計算能力的感測器來收集周遭環境的資訊。為了節省能源的消耗，感測器幾乎都進行短距離低功率的資料傳輸。因此如何在電量有限的環境下，有效地與其它裝置做短距離且定期的資訊溝通，以延長網路生命週期，是一大具有挑戰性的議題。在無線感測網路下，LEACH 是一個最典型的有效節能分群演算法。在LEACH 中，節點被分為多個叢集，以減少訊息直接由節點傳送到基地台的能量消耗。每個叢集擁有一個叢集首及數個叢集成員，叢集首負責接收其他叢集節點的資料再轉傳至基地台。叢集首是由所有節點輪流擔任，因此節點所消耗的能量較平均，藉此可以有效的增長網路的生命週期。 在本篇論文中，我們提出了一個有效節能的分群演算法稱為EECS，EECS 是一個以LEACH 為基礎進而衍伸的有效節能叢集式演算法。EECS 在設定階段中提出了一個叢集首排程演算法。在各個叢集內透過此演算法選出數個候選節點，輪流作為每回合的叢集首，希望藉此能減少網路的重分群次數。在每回合開頭也多加了一個重分群條件的判斷，來維持網路中叢集的平衡。在本文最後我們使用ns-2 模擬實驗來驗證我們所提出的方法，數據結果顯示EECS 不僅能有效降低能量的消耗，也能增加封包的傳輸量。

In recent years, the rapid development of the Internet of Things (IoT) has created great interest in the research on machine to machine (M2M) and wireless sensor networks (WSN). M2M is widely applied to services such as individual health monitoring, smart grids, intelligent transportation, smart homes, environmental monitoring, etc. In the application of the Internet of Things, many devices use sensors with restriction on their power supply, communications, and calculation ability to collect data of their surroundings. In order to reduce the consumption of energy, almost all of the sensors transmit data over a short distance and with low power. Therefore, it is a very challenging matter, given that energy is limited, to periodically transport data to other devices at a short distance and to extend the network lifetime in an effective manner. In a WSN, Low Energy Adaptive Clustering Hierarchy (LEACH) is the most common clustering algorithm used to effectively conserve energy. In LEACH, nodes are divided into multiple clusters in order to reduce the consumption of energy when data is directly transmitted from the nodes to the base station. In each cluster, there is a cluster head and multiple cluster members. The cluster head is responsible for receiving data from other nodes in the cluster, and then in turn transmitting it to the base station. Each of the nodes takes a turn to work as the cluster head, and as a result the energy consumption of the nodes is relatively even, which can effectively extend the network lifetime. In this thesis, we propose a clustering algorithm that can effectively conserve energy, which we have named the Energy-Efficient Clustering Scheme (EECS). EECS is an energy efficient clustering scheme that has evolved using LEACH as a basis. EECS includes a cluster head scheduling algorithm during the set-up phase. In each cluster, several candidate nodes are selected by this algorithm to take turns working as the cluster head in each round, with the hope that the number of re-clustering of the network can be decreased. At the beginning of each round, a determination of whether to re-cluster based on the use of re-clustering conditions is added in order to maintain the balance of the clusters in the network. At the end of this thesis, we use the ns-2 simulation experiment to evaluate the our proposed. The resulting data shows that EECS is not only able to effectively reduce the consumption of energy, but also to increase the transmission quantity of the packets.