مقاله انگلیسی رایگان در مورد الگوریتم خوشه بندی برای طول عمر شبکه – IEEE 2017

Wireless sensor networks (WSNs) are collections of low-cost, low-power sensor devices, referred to as nodes, distributed throughout a sensor field. The number of sensor nodes making up a WSN can range from a few hundred to a few thousand. Possible applications include military, agricultural, automotive, space, and environmental concerns making WSNs a topic of large amounts of research over the past few decades. Energy limitations persist due to the interest in minimizing the cost and physical footprint associated with the individual sensor nodes. As a direct consequence of the limited energy characteristics of the sensor nodes that comprise WSNs, the major challenges in this field relate to communication, data storage, and computational capability. Communication methods are necessary to allow data transmission between nodes and to ultimately transmit data collected by sensor nodes to a centralized receiver, known as a base station. A common method of decreasing overall energy consumption is through hierarchical communication routing methods known as clustering. Clustering protocols are characterized by dividing the network into subsections or ‘clusters’ of fixed or varying numbers of nodes. Data is transmitted from the sensor nodes within a cluster to the base station through an elected clusterhead (CH). Cluster-head responsibilities are usually divided equally among sensor nodes, electing a new cluster-head after each successful data packet transmission, which is referred to as a round. In [1] a pioneering hierarchical cluster protocol known as the Low-Energy Adaptive Clustering Hierarchy (LEACH) is introduced. The LEACH protocol achieved a drastic improvement in overall network lifetime by as much as a factor of eight, when compared to the conventional direct transmission communication and minimumtransmission-energy (MTE) protocols common at the time. Node decay is also seen to occur more uniformly allowing for a more even distribution of sensors throughout the life of the sensor network. Since the development of the LEACH protocol, numerous advances have been made, further improving upon its performance, with a large focus on cluster-head selection algorithms [2]. The majority of related WSN research has been focused on stationary sensor nodes. However, in some applications the sensor nodes will not be stationary. In this case, common protocols such as LEACH, see a significant breakdown in performance. In [3] LEACH-Mobile is introduced as a variation of the LEACH protocol in which considerations are made to better accommodate sensor node movement. One key assumption with LEACH is that any node has the capability to transmit its data directly to the base station. In many applications the sensor nodes will not have this capability. LEACH-Mobile is mainly focused on improving network performance, when this assumption is not valid. In this case a large amount of data is lost when nodes move out of range of their cluster-heads. LEACH-Mobile’s primary focus is on restructuring node clusters once sensor nodes move out of range during LEACH’s steady-state phase. In [3] and [4] it is shown that LEACH-Mobile is an improvement over LEACH when loss of data is considered. However, it is also shown that energy consumption worsened significantly in LEACH-Mobile due to the increased messaging required to reform node clusters. In [5], the mobility of the cluster-head is considered in the clusterhead election process to further improve upon the performance of LEACH-Mobile. It is shown that the enhancement improves data transmission by as much as 18% but at the cost of increased computational overhead and energy consumption. This work proposes LEACHCCH (LEACH – Centered Cluster-head), which is a modified LEACH protocol, directed at improving network lifetime when sensor nodes are mobile.