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Void Hole and Collision Avoidance in Geographic and Opportunistic Routing in Underwater Wireless Sensor Networks
Abstract
Underwater Wireless Sensor Networks (UWSNs) facilitate an extensive variety of aquatic applications such as military defense, monitoring aquatic environment, disaster prevention, etc. However UWSNs routing protocols face many challenges due to adverse underwater environment such as high propagation and transmission delays, high deployment cost, nodes movement, energy constraints, expensive manufacture, etc. Due to random deployment of nodes void holes may occur that results in the failure of forwarding data packet. In this research work we propose two schemes, Geographic and Opportunistic Routing using Backward Transmission (GEBTR) and Geographic and Opportunistic Routing using Collision Avoidance (GECAR) for UWSNs. In aforesaid scheme fall back recovery mechanism is used to find an alternative route to deliver the data when void occurs. In later, fall along with nomination of forwarder node which has minimum number of neighbor nodes is selected. Simulation results shows that our techniques outperforms compared with baseline solution in terms of packet delivery ratio by 5% in GEBTR and 45%t in GECAR, fraction of void nodes by 8% and 11% in GECAR and energy consumption by 8% in GEBTR and 10% in GECAR.
... Geographic information of nodes was utilized to construct two routing mechanisms in [17]. The first utilized finding backward paths from a void-hole to transfer information to the sea surface. ...
In wireless underwater sensor networks (WUSNs), network protocols for information routing are usually designed when a significant number of nodes are present in the network. Therefore, for sparse conditions, when a noticeable reduction in the number of nodes occurs, the performance of such protocols exhibits a degraded behavior pattern. To cope with routing issues when sparse conditions prevail, two routing algorithms for WUSNs are proposed in this paper. They are energy-aware scalable reliable and void-hole mitigation routing (ESRVR) and cooperative energy-aware scalable reliable and void-hole mitigation routing (Co-ESRVR). The ESRVR uses a number of strategies. Firstly, it uses two hop neighbors’ information to develop routing trajectories for information advancement, as one hop information cannot avoid a void-hole, a condition when a node is not able to find neighbors towards the sea surface, and more than two hop information is difficult to obtain when sparse conditions prevail. Secondly, when a void-hole still exists, the protocol uses a backward transmission mechanism to find other routing paths to deliver packets to the end target. Thirdly, the time by which a packet is held by a node prior to transmission is short for the nodes with low energy, depth and high count of neighbors. This reduces packets loss and avoids congestion of the channel. It also helps the nodes with no or few neighbors to hold the packet for a significant chunk of time until they find suitable neighbors, due to sea tides and currents, for further packets’ advancement. The Co-ESRVR further adds reliability to information advancement by adding routing in a cooperative fashion to ESRVR, which involves packets advancement to destination along two paths: directly from source and via a relayed path. This provides multiple paths for data advancement to the sea surface, so that if one path is badly affected by the harsh sea characteristics, others may not be. Unlike the counterpart protocol, the proposed algorithms are not dependent on a node’s geographical location or the distance from the sea surface, which increases their scalability and reduces the computational complexity. Performance analysis displays superior behavior patterns of the proposed algorithms over the counterpart in terms of the compared characteristics.
The purpose of underwater acoustic sensor networks (UWASNs) is to find varied applications for ocean monitoring and exploration of offshore. In majority of these applications, the network comprises of several sensor nodes deployed at different depths in water. The sensor nodes which are situated in depth, at the sea bed, are unable to communicate unswervingly with those nodes which are close to the surface level; these nodes necessitate multi-hop communication which is facilitated by suitable routing plan. The working of UWASNs is affected by some constraints like high transmission delay, energy consumption, deployment, long propagation delay and high attenuation. Apart from this, the existence of void region in the route can also affect the overall performance of UWASNs. So, the void region can be avoided by considering the best forwarder node. The selection of the best forwarder node depends on depth variance, depth difference, residual energy, and link quality. Apart from this, an angle is also considered to select the best forwarder node. This paper presents an energy efficient and void region avoidance routing. The concept of grey wolf optimization algorithm is used here to select the best forwarder node. The proposed work increases the network lifetime by avoiding the void region and also balancing the network energy. The proposed work is simulated in the MATLAB platform and compared with weighting depth and forwarding area division depth-based routing and energy and depth variance-based opportunistic void avoidance schemes. This work achieves the packet delivery ratio 96% with varying transmission range up to 1000 m at 180 node size. Along with this, it decreases the end-to-end delay and average number of dead nodes up to 53% and 145, respectively. This work also improves the overall network lifetime and reduces the transmission delay. This work also propagates 55% less copies of data packets. Similar to this, some other performance metrics are also explained in the results section.
Due to limited energy resources, energy balancing becomes an appealing requirement/ challenge in Underwater Wireless Sensor Networks (UWSNs). In this paper, we present a Balanced Load Distribution (BLOAD) scheme to avoid energy holes created due to unbalanced energy consumption in UWSNs. Our proposed scheme prolongs the stability period and lifetime of the UWSNs. In BLOAD scheme, data (generated plus received) of underwater sensor nodes is divided into fractions. The transmission range of each sensor node is logically adjusted for evenly distributing the data fractions among the next hop neighbor nodes. Another distinct feature of BLOAD scheme is that each sensor node in the network sends a fraction of data directly to the sink by adjusting its transmission range and continuously reports data to the sink till its death even if an energy hole is created in its next hop region. We implement the BLOAD scheme, by varying the fractions of data using adjustable transmission ranges in homogeneous and heterogeneous simulation environments. Simulation results show that the BLOAD scheme outperforms the selected existing schemes in terms of stability period and network lifetime.
Underwater wireless sensor networks (UWSNs) have been showed as a promising technology to monitor and explore the oceans in lieu of traditional undersea wireline instruments. Nevertheless, the data gathering of UWSNs is still severely limited because of the acoustic channel communication characteristics. One way to improve the data collection in UWSNs is through the design of routing protocols considering the unique characteristics of the underwater acoustic communication and the highly dynamic network topology. In this paper, we propose the GEDAR routing protocol for UWSNs. GEDAR is an anycast, geographic and opportunistic routing protocol that routes data packets from sensor nodes to multiple sonobuoys (sinks) at the sea's surface. When the node is in a communication void region, GEDAR switches to the recovery mode procedure which is based on topology control through the depth adjustment of the void nodes, instead of the traditional approaches using control messages to discover and maintain routing paths along void regions. Simulation results show that GEDAR significantly improves the network performance when compared with the baseline solutions, even in hard and difficult mobile scenarios of very sparse and very dense networks and for high network traffic loads.
We propose forwarding-function (íµí°¹ íµí°¹) based routing protocol for underwater sensor networks (UWSNs): improved adaptive mobility of courier nodes in threshold-optimized depth-based-routing (iAMCTD). Unlike existing depth-based acoustic protocols, the proposed protocol exploits network density for time-critical applications. In order to tackle flooding, path loss, and propagation latency, we calculate optimal holding time (íµí°» íµí±) and use routing metrics: localization-free signal-to-noise ratio (LSNR), signal quality index (SQI), energy cost function (ECF), and depth-dependent function (DDF). Our proposal provides on-demand routing by formulating hard threshold (íµí°» th), soft threshold (íµí± th), and prime energy limit (íµí±
prime). Simulation results verify effectiveness and efficiency of the proposed iAMCTD.
In duty-cycled wireless sensor networks running asynchronous MAC protocols, the time when a sender waits for its receiver to wake up and receive the packet is the major source of energy consumption. Opportunistic routing can reduce the sender wait time by allowing multiple candidate receivers, but by doing that it suffers from redundant packet forwarding due to multiple receivers waking up at the same time. Thus, number of forwarders should be controlled in a way that overall forwarding cost is minimized considering both sender wait time and cost of redundant packet forwarding. Also, in order to prolong network lifetime, candidate forwarders should be selected so that load is balanced among nodes. We propose ORR, an opportunistic routing protocol that addresses the two issues. First, optimal number of forwarders is calculated based on forwarding cost estimation, which is derived from duty cycle and network topology. Second, the metric used for selecting forwarders considers residual energy so that more traffic is guided through nodes with larger remaining energy. The resulting routing protocol is proven to avoid loops and shown to achieve longer network lifetime compared to other protocols regardless of duty cycle and network topology.
The concentration of data traffic toward sink makes sensor nodes nearby have heavier communication burden and more quickly use up their energy, leading to energy hole problem. Sink mobility can realize load balancing data delivery by changing the hotspots around the sink as the sink moves. However, sink mobility also brings about the problem of localization of sink. Frequently broadcasting of mobile sinks' position will generate significant overhead. In this paper, we propose a novel heterogeneous adaptive relay chain routing protocol with a few mobile relay nodes, which is applied to large-scale 1-D long chain network. Mobile relay node is the sink of local subnetwork. The protocol achieves the following performances. First, through scheduled movement of the mobile relay nodes, load balancing is achieved not only among sensor nodes but also among high tier relay nodes in continuous data delivery model. Second, in the context of clock synchronization among nodes, every node decides its operating state by algorithm stored in its own processor. So, there is no need for advertisement of mobile relay nodes' location. Only a few messages for clock synchronization among nodes are needed. Third, by synthetically utilizing node deployment strategy and routing protocol, base station can real-time monitoring residual energy of sensor nodes for timely maintenance, which can extend the protocol to be suitable for event-driven and query-driven data delivery models. Finally, the performances are evaluated via extensive simulations.
The design of routing protocols for Underwater Acoustic Sensor Networks (UASNs) poses many challenges due to long propagation, high mobility, limited bandwidth, multi-path and Doppler effect. Because of the void-hole caused by the uneven distribution of nodes and sparse deployment, the selection of next hop forwarding nodes only based on the state of current node may result in the failure of forwarding in the local sparse region. In order to reduce the probability of encountering void holes in the sparse networks, in this paper we present weighting depth and forwarding area division DBR routing protocol, called WDFAD-DBR. The novelties of WDFAD-DBR lie in: firstly, next forwarding nodes are selected according to the weighting sum of depth difference of two hops, which considers not only the current depth but also the depth of expected next hop. In this way, the probability of meeting void holes is effectively reduced. Secondly, the mechanisms for forwarding area division and neighbor node prediction are designed to reduce the energy consumption caused by duplicated packets and neighbors' requests, respectively. Thirdly, we make theoretical analyses on routing performance in case of considering channel contending with respect to delivery ratio, energy consumption and average end-to-end delay. Finally we conduct extensive simulations using NS-3 simulator to verify the effectiveness and validity of WDFAD-DBR.
Underwater acoustic sensor network (UASN) is a promising technique, which will facilitate a wide range of aquatic applications. However, because of adverse underwater environments, UASN faces grand challenges and problems such as limited bandwidth, node movement, long propagation delay, three-dimension deployment, energy-constraint, expensive manufacture and deployment costs. In order to address these problems and challenges, in this paper we propose an adaptive hop-by-hop vector-based forwarding routing protocol on the basis of HH-VBF (called AHH-VBF). Firstly, during the transmission process, the radius of virtual pipeline is adaptively changed hop by hop to restrict the forwarding range of packets so that the transmission reliability can be guaranteed effectively in the sparse sensor region and the duplicated packets can be reduced in the dense sensor region; secondly, the transmission power level is also adaptively adjusted hop by hop in cross-layer fashion so that the energy-efficiency can be improved effectively; thirdly, forwarding nodes are selected based on the distance from current node to destination node so that the end-to-end delays are reduced effectively. Eventually, we propose two metrics: propagation deviation factor and effective neighbor number, to evaluate the network performance of AHH-VBF. We conduct extensive simulations using ns-3 simulator and perform theoretical analyses to evaluate the network performance. Our experimental results verified that the AHH-VBF routing protocol outperforms HH-VBF protocol, naïve Flooding and RDBF in terms of energy efficiency, end-to-end delay and data delivery ratio.
With the advance of the Internet of Underwater Things, smart things are deployed under the water and form the underwater wireless sensor networks (UWSNs), to facilitate the discovery of vast unexplored ocean volume. A routing protocol, which is not expensive in packets forwarding and energy consumption, is fundamental for sensory data gathering and transmitting in UWSNs. To address this challenge, this paper proposes E-CARP, which is an enhanced version of the Channel-Aware Routing Protocol (CARP) developed by S. Basagni et al., to achieve the location-free and greedy hop-by-hop packet forwarding strategy. Generally, CARP does not consider the reusability of previously collected sensory data to support certain domain applications afterwards, which induces data packets forwarding which may not be beneficial to applications. Besides, the PING-PONG strategy in CARP can be simplified for selecting the most appropriate relay node at each time point, when the network topology is relatively steady. These two research problems have been addressed by our E-CARP. Simulation results validate that our technique can decrease the communication cost significantly and increase the network capability to a certain extent.
Underwater Acoustic Sensor Networks (UASNs) offer their practicable applications in seismic monitoring, sea mine detection and disaster prevention. In these networks, fundamental difference between operational methodologies of routing schemes arises due to the requirement of time-critical applications therefore, there is a need for the design of delay-sensitive techniques. In this paper, Delay-Sensitive Depth-Based Routing (DSDBR), Delay-Sensitive Energy Efficient Depth-Based Routing (DSEEDBR) and Delay-Sensitive Adaptive Mobility of Courier nodes in Threshold-optimized Depth-based routing (DSAMCTD) protocols are proposed to empower the depth-based routing schemes. The performance of the proposed schemes is validated in UASNs. All of the three schemes formulate delay-efficient Priority Factors (PF) and Delay-Sensitive Holding time (DSH T) to minimize end-to-end delay October 6, 2014 DRAFT 2 with a small decrease in network throughput. These schemes also employ an optimal weight function (W F) for the computation of transmission loss and speed of received signal. Furthermore, solution for delay lies in efficient data forwarding, minimal relative transmissions in low-depth region and better forwarder selection. Simulations are performed to assess the proposed protocols and the results indicate that the three schemes largely minimize end-to-end delay along with improving the transmission loss of network.
Providing scalable and ecient routing services in underwater sensor net- works (UWSNs) is very challenging due to the unique characteristics of UWSNs. Firstly, UWSNs often employ acoustic channels for communications because radio signals do not work well in water. Compared with radio-frequency channels, acous- tic channels feature much lower bandwidths and several orders of magnitudes longer propagation delays. Secondly, UWSNs usually have very dynamic topology as sen- sors move passively with water currents. Some routing protocols have been proposed to address the challenging problem in UWSNs. However, most of them assume that the full-dimensional location information of all sensor nodes in a network is known in prior through a localization process, which is yet another challenging issue to be solved in UWSNs. In this paper, we propose a depth-based routing (DBR) protocol. DBR does not require full-dimensional location information of sensor nodes. Instead, it needs only local depth information, which can be easily obtained with an inex- pensive depth sensor that can be equipped in every underwater sensor node. A key advantage of our protocol is that it can handle network dynamics eciently with- out the assistance of a localization service. Moreover, our routing protocol can take advantage of a multiple-sink underwater sensor network architecture without intro- ducing extra cost. We conduct extensive simulations. The results show that DBR can achieve very high packet delivery ratios (at least 95%) for dense networks with only small communication cost.