Underwater spray and wait routing technique for mobile ad-hoc networks

1648-1655The underwater mobile ad-hoc networks comprise sensor nodes that are source nodes for gathering underwater-related data. Relay nodes are the mobile nodes for collecting data from sensor nodes and achieving intermittent connectivity among source and destination nodes. Developing an efficient routing protocol for underwater communication is a challenging issue due to limitations of the underwater environment. Underwater mobile ad-hoc networks are intermittent networks where end-to-end path does not exist from source to destination. To overcome these problems a delay and disruption tolerant network (DTN) is a good solution. In the current paper, we consider the Spray and Wait (SaW) routing technique. In SaW, source and relay nodes represents the moving nodes, and they try to send data to destination nodes. Based on this, we propose the replica based underwater SaW (USaW) routing for underwater mobile ad-hoc networks. In USaW, source nodes are fixed to the bottom of the surface. Underwater sensor nodes replicate sensor data and provide maximum copies of data to the relay nodes that they encounter. In generally, relay nodes have high capability of transmitting data as compared to sensor nodes in an underwater environment. We analyze the performance of USaW with respect to delivery ratio, network throughput, energy consumption, end-to-end delay, and packet drop rate comparing with existing SaW and prophet routing protocols

Classification of Routing Algorithms in Volatile Environment of Underwater Wireless Sensor Networks

The planet earth is basically a planet of water with less than 30% land mass available for humans to live on. However, the areas covered with water are important to mankind for the various resources which have been proven to be valuable. Such resources are gas, oil, marine products which can be used as food, and other minerals. In view of the vast area in which these resources can be found, a network of sensors is necessary so that they can be explored. However, sensor networks may not be helpful in the exploration of these resources if they do not have a sufficiently good routing mechanism. Over the past few decades, several methods for routing have been suggested to address the volatile environment in underwater communications. These continue researches; have enhanced the performance along with time. Meanwhile, there are still challenges to deal with for a better and efficient routing of data packets. Large end-to-end delays, high error channel rates, limited bandwidth, and the consumption of energy in sensor network are some such challenges. A comprehensive survey of the various routing methods for the partially connected underwater communication environment are presented in this paper

Analyzing the performance of localization protocols for underwater acoustic sensor networks

Sualtı Duyarga Ağları (SDA) insan eliyle tehlikeli veya olanaksız sayılabilecek sualtı görevlerinde kullanılırlar. SDA’lar okyanusbiliminde, deprem ve tsunami tahmininde, askeri uygulamalarda, okyanus petrol platformlarının gözetlenmesinde ve çeşitli birçok alanda kullanılabilirler. Sualtı duyarga düğümleri sabit bir platforma tutturulmuş olabilir veya su içersinde serbest halde yüzebilir. Su yüzeyinden metrelerce aşağıda yüzen duyarga düğümler, gezgin sualtı duyarga ağını oluştururlar. Duyarga düğümler okyanuslardan sıcaklık, akıntı hızı, tuzluluk ve görüntü kaydı gibi veriler toplarlar. Gezgin bir SDA’da, duyarga düğümler su yüzeyinin altında, akıntıyla birlikte hareket eder ve belirli bir olayı izlerler. SDA’larda en ciddi sorunlardan biri konumlandırmadır. Konum bilgisine, veri etiketleme ve konum-tabanlı yönlendirme protokollerinde ihtiyaç duyulur. Geniş ölçekli, üç boyutlu SDA’lar için, literatürde az sayıda konumlandırma protokolü önerilmiştir. Bu makalede, İner-Çıkar düğümlerle Konumlandırma (İÇK) ve Vekil Konumlandırma (VK) yöntemlerini tanıtıp, sözkonusu yöntemlerin başarımını önceden önerilmiş olan bir başka yöntemle karşılaştırmaktayız. Bu yöntem, Geniş Ölçekli Konulmandırmadır (GÖK). Bu üç tekniğin avantaj ve dezavantajlarını gezgin bir SDA için göstermekteyiz. Benzetim sonuçlarımız GÖK’ün yüksek konumlandırma başarısına sahip olduğunu, ancak bu yöntemin beraberinde yüksek enerji tüketimi ve ek haberleşme yükü getirdiğini göstermektedir. İÇK ise, yüksek konumlandırma başarımı, yüksek kesinlik, düşük enerji tüketimi ve düşük haberleşme maliyetine sahiptir. VK ise, kabul edilebilir konumlandırma başarımı, düşük enerji tüketimi ve daha az ek yük getirmekte, buna karşılık diğerlerinden daha düşük kesinlik sağladığı görülmektedir.  Anahtar Kelimeler: Sualtı duyarga ağları, konumlandırma, duyarga ağlar.Underwater Sensor Networks (USNs) can improve naval defense, earthquake/tsunami forewarning, water pollution detection, ocean life monitoring systems, etc. Stationary Underwater Sensor Networks are ideal for securing or monitoring a fixed target region, e.g. monitoring oil drilling platforms for spill detection, harbor entrances for surveillance, ocean bottom for seismic activity observation, etc. On the other hand, mobile untethered Underwater Sensor Networks are flexible and better alternatives for short term exploration of moving targets. For instance, untethered, free-floating underwater sensors can track a chemical spill or a pollutant that may be dangerous to human health or sea life. In a sensor network, sensor nodes collect data from their surrounding and tag these data, in order to transmit them to a more powerful node for processing. Therefore, it is crucial to know the location of the sensor nodes. Location is required for data tagging, as well as, target detection, node tracking, etc. In addition, localization is essential for position-based routing algorithms which are powerful alternatives to classical routing approaches in Mobile Ad Hoc Networks (MANET). Localization is a well studied topic in terrestrial sensor networks. Nevertheless, in Underwater Sensor Networks, localization is still challenging due to several reasons: i) unavailability of the GPS; ii) low bandwidth, long delay and high bit error rate of the acoustic links; iii) necessity of high amount of sensor nodes to cover the three dimensional region. The use of GPS is limited to surface nodes because the GPS signal does not propagate through the water. In sensor networking literature, several GPS-less (GPS-free) positioning schemes have been proposed however they usually have high overhead. The underwater sensors use acoustic links and the bandwidth of those links is low even for very short distances. Moreover, acoustic communications has high propagation delay and high bit error rate. In Underwater Sensor Networks, localization protocols are expected to avoid excessive overhead and establish localization with the least possible messages. This is also enforced by the limited battery life of the underwater sensor nodes and the difficulty of recharging or replacing the batteries in an underwater application. Usually, an underwater application requires a large number of sensor nodes because the data rate of the acoustic links increases with decreasing distance and shorter ranges between nodes, means that more sensor nodes are needed to cover the three dimensional oceanographic zone. In addition, in a mobile Underwater Sensor Network localization should be repeated and stale location information should be cleared periodically. Considering all these challenges, it is essential to develop novel localization protocols tailored for mobile Underwater Sensor Networks. In this article, we introduce two distributed, scalable localization techniques; Dive and Rise Localization (DNRL) and Proxy Localization (PL). In DNRL, mobile beacons ascend and descend in the water to deliver their GPS driven coordinates. In PL, the already localized nodes act like beacons likewise multi-stage localization which is a preliminary version of PL (Erol et al., 2008). Unlike the previous work, in PL the non-localized nodes use a different metric to choose the best possible proxies among the candidates which enhances the performance of the protocol. Here, we compare the performance of PL, DNRL and Large-Scale Localization (LSL). LSL is a technique from the literature (Zhou et al., 2007). We evaluate the performance of these schemes in terms of localization success, accuracy, overhead and energy consumption. Since we compare the performance of the localization techniques for a mobile Underwater Sensor Network, a realistic underwater mobility model is essential. Recently, the works of Caruso et al. (2008) and Erol et al. (2008) have applied the real ocean current behavior to Underwater Sensor Networks. We use the "Meandering Current Mobility with Surface Effect" (MCM-SE) model to compare the performance of the three localization schemes for a mobile underwater sensor network. The main aim of the article is to provide a comparison between recently proposed localization schemes for Underwater Sensor Networks. Based on the simulation results, we compare and analyze the performance of three recent methods that are developed for distributed localization in large-scale Underwater Sensor Networks in terms of localization ratio, accuracy, protocol overhead and energy consumption.  Keywords: Sensor networks, underwater sensor networks, localization

Dynamic localization plan for underwater mobile sensor nodes using fuzzy decision support system.

Underwater mobile sensor node localization is a key enabling technology for several subsea missions. A novel scalable underwater localization scheme, called Best Suitable Localization Algorithm (BLSA), is proposed to dynamically fuse multiple position estimates of sensor nodes using fuzzy logic, aiming at improving localization accuracy and availability along the whole trajectory in missions. Numerical simulation has been conducted to demonstrate significant improvement in localization accuracy and availability by using the proposed fuzzy inference system. The proposed method provides a costeffective localization system by harnessing all available localization methods on-board

EFFICIENT DYNAMIC ADDRESSING BASED ROUTING FOR UNDERWATER WIRELESS SENSOR NETWORKS

This thesis presents a study about the problem of data gathering in the inhospitable underwater environment. Besides long propagation delays and high error probability, continuous node movement also makes it difficult to manage the routing information during the process of data forwarding. In order to overcome the problem of large propagation delays and unreliable link quality, many algorithms have been proposed and some of them provide good solutions for these issues, yet continuous node movements still need attention. Considering the node mobility as a challenging task, a distributed routing scheme called Hop-by-Hop Dynamic Addressing Based (H2- DAB) routing protocol is proposed where every node in the network will be assigned a routable address quickly and efficiently without any explicit configuration or any dimensional location information. According to our best knowledge, H2-DAB is first addressing based routing approach for underwater wireless sensor networks (UWSNs) and not only has it helped to choose the routing path faster but also efficiently enables a recovery procedure in case of smooth forwarding failure. The proposed scheme provides an option where nodes is able to communicate without any centralized infrastructure, and a mechanism furthermore is available where nodes can come and leave the network without having any serious effect on the rest of the network. Moreover, another serious issue in UWSNs is that acoustic links are subject to high transmission power with high channel impairments that result in higher error rates and temporary path losses, which accordingly restrict the efficiency of these networks. The limited resources have made it difficult to design a protocol which is capable of maximizing the reliability of these networks. For this purpose, a Two-Hop Acknowledgement (2H-ACK) reliability model where two copies of the same data packet are maintained in the network without extra burden on the available resources is proposed. Simulation results show that H2-DAB can easily manage during the quick routing changes where node movements are very frequent yet it requires little or no overhead to efficiently complete its tasks

EFFICIENT DYNAMIC ADDRESSING BASED ROUTING FOR UNDERWATER WIRELESS SENSOR NETWORKS

This thesis presents a study about the problem of data gathering in the inhospitable underwater environment. Besides long propagation delays and high error probability, continuous node movement also makes it difficult to manage the routing information during the process of data forwarding. In order to overcome the problem of large propagation delays and unreliable link quality, many algorithms have been proposed and some of them provide good solutions for these issues, yet continuous node movements still need attention. Considering the node mobility as a challenging task, a distributed routing scheme called Hop-by-Hop Dynamic Addressing Based (H2- DAB) routing protocol is proposed where every node in the network will be assigned a routable address quickly and efficiently without any explicit configuration or any dimensional location information. According to our best knowledge, H2-DAB is first addressing based routing approach for underwater wireless sensor networks (UWSNs) and not only has it helped to choose the routing path faster but also efficiently enables a recovery procedure in case of smooth forwarding failure. The proposed scheme provides an option where nodes is able to communicate without any centralized infrastructure, and a mechanism furthermore is available where nodes can come and leave the network without having any serious effect on the rest of the network. Moreover, another serious issue in UWSNs is that acoustic links are subject to high transmission power with high channel impairments that result in higher error rates and temporary path losses, which accordingly restrict the efficiency of these networks. The limited resources have made it difficult to design a protocol which is capable of maximizing the reliability of these networks. For this purpose, a Two-Hop Acknowledgement (2H-ACK) reliability model where two copies of the same data packet are maintained in the network without extra burden on the available resources is proposed. Simulation results show that H2-DAB can easily manage during the quick routing changes where node movements are very frequent yet it requires little or no overhead to efficiently complete its tasks