以能量分配改良群組叢集協定

Improving the group cluster hierarchy protocol by the ration of energy

戴禎億(Chen-Yi Dai)

指導教授 ： 廖俊鑑

朝陽科技大學/資訊學院/網路與通訊研究所/碩士(2009年)

摘要

無線感測網路(Wireless Sensor Networks, WSN)的運作是由許多的感測節點(sensor node)所組成，感測節點收集感應資料，經由無線網路傳送到基地台。由於無線感測網路一旦佈署好後，感測節點的電池便不易更換。因此，在無線感測網路的研究中，如何減少感測節點的能量消耗，達到延長無線感測網路的壽命是一項非常重要的議題。
先前對於減少能量消耗的相關研究中，以叢集式架構最為常見。在叢集式架構裡，所有的感測節點組織成若干叢集，每個叢集皆推選出一個叢集頭(cluster head)，由叢集頭聚集其他感測節點感測的資料，再傳送到基地台(base station)。以叢集式架構為基礎的繞路協定中，最典型的就是LEACH協定(Low-Energy Adaptive Clustering Hierarchy)。LEACH以機率的方式選取叢集頭，所有的感測節點以隨機並輪流的方式當選叢集頭。
但是，以機率的方式產生的叢集頭數量與我們期望的叢集頭數量可能會有落差，因此SGCH協定(Steady Group Clustering Hierarchy) 改良叢集頭選取的演算，將感測節點群組化(group)。SGCH設定群組的數量相等於我們期望的叢集頭數量，使每回合叢集頭產生的數量與我們期望的數量相同。在群組化的階段，SGCH使各個群組皆擁有相同的初始能量，平衡網路中感測節點的能量負載，使其適用於能量異質性感測網路(heterogeneous WSN)。
由於感測節點在傳送資料時，距離越遠將消耗越多能量。在SGCH中，距離基地台越遠的群組將需要花費更多的電力去傳送到基地台，由於各個群組的能量皆相同，所以距離基地台越遠的群組將會死亡越快。
本論文針對SGCH的感測節點群組化演算法提出改良的方法。在感測節點群組化時，以各個群組與基地台距離比例為依據，分配各個群組的初始能量，使得距離基地台越遠的群組擁有越多的初始能量，達到平衡群組之間的能量負載。經由模擬實驗顯示，我們的方法在同質性、二階層異質性、三階層異質性和多階層異質性感測網路下，都能有效延長無線感測網路的存活時間，並使得感測節點的死亡時間分佈更為接近，並且更適用於異質性感測網路。

關鍵字

叢集頭 ； 異質性感測網路 ； 群組

並列摘要

Wireless sensor network (WSN) consists large number of sensor nodes. The nodes collect the sensed data and transmit to the base station (BS) by wireless communication. When the sensor nodes are deployed, the batteries of sensor nodes are difficult to replace. Therefore, minimizing the energy consumption for maximizing the batteries lifetime becomes a key challenge to design the WSN protocols.
Cluster is the one of energy-efficient schemes for WSN. In the cluster scheme, several nodes are elected as cluster head (CH). And then CHs aggregate the data from the nodes of their respective cluster and forward the fusion data to BS. The most popular routing protocol based on cluster scheme is called LEACH, which is proposed for CH selection by probability. However, LEACH selects the CHs by probability in each round, the actual number of CHs with the expected number maybe different.
SGCH (Steady Group Clustering Hierarchy) is based on LEACH to improve the CH selection algorithm by grouping the nodes. In SGCH, the number of groups is equal to the number of expected CHs and the energy of each group is the same to balancing the energy load of WSN. But the initial energy of groups in SGCH are the same, therefore the nodes of farther group from BS be die soon. Because of the energy consumption in WSN is relation to the transmission distance, which nodes cost more energy to transmit the data for farther distance.
In this paper, we propose a method to improve the grouping algorithm for SGCH. We consider the ration of energy for groups is according to the distance of each group between BS. So, the farther group from BS has more initial energy to balance the energy load of group in WSN.
Finally, we simulate the propose method to compare LEACH, SGCH and other protocols in different environment of WSN. The simulation results show that our propose method is better than other protocols and more suitably for heterogeneous WSN

並列關鍵字

group ； heterogeneous WSN ； cluster head

參考文獻

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