A Mobile Sink Based Uneven Clustering Algorithm for Wireless Sensor Networks

Large scale Wireless Sensor Networks (WSNs) often utilize multiple mobile sink nodes to improve the network lifetime and scalability. However, most of the studies conducted in this context, consider unlimited buffer capacity for the sink nodes. But, this model cannot truly describe the behavior of WSNs and causes congestion in the sink nodes. To solve this problem, in this paper, we use limited buffer capacity for each mobile sink node in WSNs and present a two-level Fuzzy Logic Controller (FLC)-based dynamic clustering scheme and congestion prevention. In this scheme, sink nodes try to predict current load based on their loads in previous rounds by using ARIMA method and based on it, the first FLC selects the nearest uncongested sink node from multiple available mobile sink nodes. Then, the second FLC applies the output of the first FLC to select appropriate nodes as cluster heads to mitigate the energy consumption in the network. Extensive simulation results indicate the effectiveness of the proposed fuzzy logic-based solution in reducing congestion in the mobile sink nodes and improving load balancing in them which these result in the network lifetime improvement and decreasing the number of retransmissions.

Towards an energy balancing solution for wireless sensor network with mobile sink node

Maximization of lifetime of wireless sensor network (WSN) is an emerging area of research in present scenario. Many authors are performing their research work, so that they could achieve lower energy consumption for the sensor network which leads to increase in lifetime of network. Our work focuses on sink mobility in a fixed trajectory within a wireless sensor network while sensed data are required to be collected. We divide the whole sensor network into two different regions as direct communication area (DCA) and multi-hop communication area (MCA). Sensors node that lies in DCA is at one hop count distance from the sink node trajectory while sensors within MCA are at more than one hop count from the trajectory. We considered all the sensors that are within DCA as subsink nodes. During sink mobility, whenever a subsink is closer to the mobile sink node, then it starts transmitting its data to the sink node. But those sensors that are within MCA needs to search an appropriate sink node for sending its sensed data to the subsink so that on further stage, that subsink could provide those data to the sink node whenever it is in nearest proximity of that subsink. Basically, a sink node is the ultimate destination for the data while a subsink node acts as a relay node for the nodes that are within MCA. So our work is to find out the appropriate subsink node from a given set of subsinks. For doing so, we used location-aided routing on global positioning system (GPS)-enabled sensors and sink node. Our work is validated through simulation experiments using NS-2.

We investigate a broadcast scenario that a mobile sink disseminating broadcast packets while moving in asynchronous wireless sensor networks (WSNs), to prolong the network lifetime and reduce the broadcast delay. Such a scenario may yield multiple logical sink nodes in WSNs and the moving speed and trajectory of the mobile sink have the significant impact on the speed and efficiency of the broadcast. Thus, the conventional broadcast protocols may not fit for the mobile sink scenario. We propose a fast and efficient broadcast (FEB) protocol with a mobile sink in asynchronous WSNs. We analyze the moving pattern as well as the travel speed of the mobile sink. We jointly consider the broadcast process, the node location, and the neighbor coverage information within two-hops and then propose an efficient broadcast scheme together with a heuristic moving strategy for the mobile sink. The proposed broadcast scheme needs to exchange node coverage information before the transmission begins, thus to avoid redundant packet transmissions, and the proposed moving pattern strategy decreases the network broadcast delay by moving the mobile sink to monitoring areas, where fewer nodes are covered by the broadcast process. The simulation results show that our proposed protocol significantly reduces the broadcast delay and energy consumption.

무선센서네트워크는 센서필드안에서 어떤 이벤트를 센싱하는 수많은 센서노드들로 구성된다. 무선센서네트워크에서 이벤트를 인식한 소스노드와 이 값을 처리하는 싱크노드간에 데이터가 전송되며 싱크노드의 이동성을 고려한 에너지 효율적인 라우팅 기법이 필요하다. 본 연구 에서는 데이터패스 템플릿을 이용하여 미리 정해진 방향으로 소스노드로부터의 데이터공고, 싱크노드로부터의 데이터요구 메시지를 전송한다. 다음 단계로 센싱한 데이터를 단거리계산법을 사용하여 싱크노드에게 전송한다. 그리드 개념과 이동성 싱크가 존재하는 센서네트워크에 대한 기존의 TTDD 라우팅 프로토콜과 CBPER 프로토콜을 본 연구에서 제안한 SPDR 프로토콜과 시뮬레이션을 통하여 비교한 결과, 제안된 프로토콜이 기존의 TTDD나 CBPER보다 향상된 에너지 효율성을 가졌음을 보여준다. Wireless sensor networks have many sensor nodes which response sudden events in a sensor fields. Some efficient routing protocol is required in a sensor networks with mobile sink node. A data-path template is offered for the data announcement and data request from source node and sink node respectively. Sensed data are transferred from source node to sink node using short-distance calculation. Typical protocols for the wireless networks with mobile sink are TTDD(Two-Tier Data Dissemination) and CBPER(Cluster-Based Power-Efficient Routing). The porposed SPDR(Short-Path Data Routing) protocol in this paper shows more improved energy efficiencies from the result of simulations than the typical protocols.

An efficient networks’ energy consumption and Quality of Services (QoS) are considered the most important issues, to evaluate the route quality of the designed routing protocol in Wireless Sensor Networks (WSNs). This study is presented an evaluation performance technique to evaluate two routing protocols: Secure for Mobile Sink Node location using Dynamic Routing Protocol (SMSNDRP) and routing protocol that used K-means algorithm to form Data Gathered Path (KM-DGP), on small and large network with Group of Mobile Sinks (GMSs). The propose technique is based on QoS and sensor nodes’ energy consumption parameters to assess route quality and networks’ energy usage. The evaluation technique is conducted on two routing protocols in two phases: The first phase is used to evaluate the route quality and networks’ energy consumption on small WSN with one mobile Sink Node (SN) and GMSs. The second phase, is used to evaluate the route quality and networks’ energy consumption on large network (four WSNs) with GMSs. The two phases are implementated by creating five sceneries via using NS2.3 simulator software. The implementation results of the proposed performance evaluation technique have demonstrated that SMSNDRP gives better networks’ energy consumption on small single network in comparison with KM-DGP. Also, it gives high quality route in large network that used four mobile SN, in contrast to KM-DGP that used sixteen mobile SNs. While in large network, it found that KM-DGP with sixteen mobile SNs gives better networks’ energy consumption in comparison with SMSNDRP with four mobile SNs.

Sink mobility has attracted much research interests in Wireless Sensor Networks (WSNs), because it could provide energy saving and reduce latency during data collection. However, the mobile sink node is still a single point of failure in many WSNs applications, thus needs to be particularly protected against adversaries. We propose in this paper a moving strategy for the mobile sink which prevents tracking or detecting on it by adversaries during its data collection phase around the sensor field. Our moving strategy aims to selecting a trajectory for mobile sink node, which minimizes the total number of message communication from all static sensor nodes to the mobile sink node (including multi-hop relaying) and thereby reducing the possibility of being detected by the adversaries. We also employed a routing protocol on sensor nodes to forward the data to mobile sink node with shortest-path. Four strategies are evaluated in our simulation and the performance results show that our moving strategy we proposed achieves best goal and adapts well to the different deployment patterns.

Wireless sensor networks with the mobile sink can help to prevent the hot-spot problem and improve the network lifetime. However, in practice, the trajectories of the sink can not ideally change due to the obstacle of the environment or the requirement of the application. The constraint on trajectory of the mobile sink causes the different connection time between the mobile sink and the sensor node, which might result in the imbalance depletion of energy. We propose here an efficient data gathering policy to jointly consider the constrained mobility of the sink and the different connection time at the sensor node. The policy increases the network lifetime in wireless sensor networks with path-constrained mobile sink by optimizing the assignment sensor node. In addition, we also propose the policy to cope with the overlapped connection time of the sink and sensor node due to the movement of the sink. The simulation results demonstrate the effectiveness of the proposed policy: by carefully considering the trajectory of the sink and effectively assigning the sensor node, the network lifetime is increased.

Sensor nodes located in the vicinity of a static sink drain rapidly their batteries since they have to carry more traffic burden. This situation results in network partition, holes as well as data losses. To mitigate this issue, many research proposed the use of mobile sink in data collection as a potential solution. However, due to its speed, the mobile sink has very short communication time to pick up all data from the sensor nodes within the network, therefore the sink is forced to return back to gather the remaining data. In this paper, we propose a new data collection scheme that aims to decrease the latency and enlarge the staying time between the mobile sink and the meeting points that buffer data originated from the other sensor nodes. We have also handled the case of urgent data so that they can be delivered without any delay. Our proposed scheme is validated via extensive simulations using NS2 simulator. Our approach significantly decreases the latency and prolongs the contact time between the mobile sink and sensor nodes.

A wireless sensor network (WSN) consists of a large number of interconnected sensors, which provides unique features to visualize the real world scenario. It explores many opportunities in the field of research due to its wide range of applications in current fields that require survey and periodic monitoring which is inevitable in our daily life. However, the main limitations of such sensors are their resource constrained nature, mainly to conserve battery power for extending the network lifetime. We have proposed an algorithm for energy efficiency in WSN in which mobile sink node is used to operate the routing process considering the shortest path between multiple unequal clusters with reduced energy. This model also ensures non-occurrences of energy hole problems within the network area.

One of the most important considerations in designing sensor nodes in a wireless sensor network is to extend the network lifetime by minimizing the energy consumption with limited resources. The most challenging aspects of the studies conducted on this topic have been supporting the mobility of sink nodes in a wireless sensor network, and providing an efficient data dissemination approach.

Optimizing LEACH clustering algorithm with mobile sink and rendezvous nodes

Efficient energy consumption is a major problem in Wireless Sensor Network. The sink can be static or dynamic. In case of static sink, the node that is placed near the sink is utilized more than other nodes in the network due to frequent packet forwarding. This causes the node near the sink to die very soon, also further communication between the sink and other nodes in the network is disconnected. When dynamic or mobile sinks are used, the energy consumption is distributed among other nodes in the network, which increases the lifetime of the network. In this paper to know the latest position of the sink, we introduce Dynamic Hexagonal Grid Routing Protocol (DHGRP). In the first phase, the protocol divides the network by several hexagonal virtual grids to share the current position of the sink among the nodes. In the second phase, the dynamic path is selected, in case congestion occurs during data transmission or if the mobile sink is moved to a new location. The performance is evaluated by comparing with the existing ring routing protocol, Query-Driven Virtual Grid-based Data Dissemination, and Grid-Cycle Routing Protocol. The results show that the proposed DHGRP protocol has better performance in terms of energy consumption, delay, network lifetime, throughput and Packet Delivery Ratio.

Energy efficiency is a key concern and challenging research issue during the design of routing algorithms for wireless sensor networks (WSNs). In order to effectively improve the energy utilization of each sensor node and network performance, mobility technology has been widely concerned. Since the implement of mobile sink node is relatively easier than normal sensor nodes, sink mobility technology has attracted much research interest in recent years. In this paper, we propose a mobile-sink routing algorithm based on energy and distance for WSNs. Trajectories of mobile sink nodes is predictable to improve energy efficiency of sensor networks. We first lay emphasis on the study of the selection of mobile sink node number and the selection of park positions, as well as their impact on energy consumption and network lifetime. Simulation results show that both the mobile sink nodes number and park positions have great influence on network performance, and our algorithm outperforms random movement and LEACH algorithm in terms of performance like energy consumption.

In this work, we study the impact of data aggregation in WSNs with mobile sink nodes that can move at higher speeds. In these cases, propagated queries cannot be answered by using the sink's position when the query was sent, since the sink node will probably be elsewhere. Therefore, conventional data aggregation schemes may not be appropriate due to this high speed. Thus, we propose and evaluate the performance of three new algorithms for data routing and aggregation in WSNs when the sink is moving at a high speed. These algorithms explore the sink movement to create a routing graph composed of the union paths that intersect the sink's trajectory. At each hop, the sink speed and current network delays are used as metric to guide in-network data aggregation. Our results clearly show significant energy savings and efficient data delivery achieved by the proposed algorithms in different scenarios.