Amir Darehshoorzadeh

Opportunistic Routing in Wireless Networks: Models, Algorithms, and Classifications

Opportunistic Routing (OR) is a new promising paradigm that has been proposed for wireless networks. OR has gained a lot of attention from the research communities for its ability to increase the performance of wireless networks. It benefits from the broadcast characteristic of wireless mediums to improve network performance. The basic function of OR is its ability to overhear the transmitted packet and to coordinate among relaying nodes. In OR, a candidate set is a potential group of nodes that is selected as the next-hop forwarders. Hence, each node in OR can use different potential paths to send packets toward the destination. Any of the candidates of a node that have received the transmitted packet may forward it. The decision of choosing the next forwarder is made by coordination between candidates that have successfully received the transmitted packet. In OR, by using a dynamic relay node to forward the packet, the transmission reliability and network throughput can be increased. In this article, we explain the fundamental idea of OR and its important issues by providing some examples. We then categorize each of the important issues and explain them in detail. Furthermore, we illustrate different protocols from each category and compare their benefits and drawbacks. Finally, some potential directions for future research in OR is explained.

Underwater sensor networks: a new challenge for opportunistic routing protocols

Opportunistic routing (OR) is a promising paradigm that selects the next-hop forwarder on the fly. OR has gained a lot of attention from the research community for its ability to increase the performance of wireless networks. In OR a potential group of nodes (candidates) is selected to help as the next-hop forwarder. Each candidate that receives the packet can continue forwarding the packet. In OR, by using a dynamic relay node to forward the packet, the transmission reliability and network throughput are increased. Underwater sensor networks (UWSNs) collect data from the environment and transfer them to the sonobuoys on the surface to send them to a center for further processing. Because of the acoustic channels common to UWSNs, they have low bandwidth, high error probability, and longer propagation delay compared to radio channels. These properties of UWSNs make them good potential candidates for using OR concepts to deliver packets to the destination. This article reviews and compares different OR protocols proposed for UWSNs. We classify the existing approaches in different categories, discuss representative examples for each class of protocols, and uncover the requirements considered by the different protocols, as well as the design requirements and limitations under which they operate. Finally, we discuss potential future research directions for UWSNs using the OR paradigm.

On the number of candidates in opportunistic routing for multi-hop wireless networks

Opportunistic Routing (OR) is a new paradigm that has been investigated as a new way to improve the performance of multihop wireless networks by exploiting the broadcast nature of the wireless medium. In contrast to traditional routing, in OR an ordered set of nodes is selected as potential next-hop forwarders (candidates). Using more number of candidates in OR decreases the number of transmissions in the network, but this comes at the cost of increasing the signaling overhead and also the possibility of having duplicated transmissions which in turn reduces the performance of the OR protocol. The number of candidates that each node can select is an issue which is not well investigated in the literature. In this paper, we propose a Distance-based MAximum number of Candidate Estimation (D-MACE) as an approach to find the number of candidates in each node. In contrast to the traditional approaches in OR which consider an identical number of candidates for all nodes, D-MACE reduces the number of candidates in each node according to the distance between the node and the destination. We evaluate the performance of our proposal, using two relevant candidate selection algorithms. Our results show that D-MACE reduces the number of selected candidates effectively in the network, which improves the network performance compared to the case with the same number of candidates in all nodes.

Towards a novel trust-based opportunistic routing protocol for wireless networks

AbstractOpportunistic routing is a promising research area in the context of wireless network communications. Security and trustworthy of routing in this field, however, needs to be considerably researchedn. In this paper, a novel trust establishment algorithm is proposed, designed, and implemented specifically for opportunistic routing protocols which benefits from direct interactions between wireless nodes. The proposed trust model benefits from a novel watchdog mechanism considering not only forwarding behaviour of nodes but also the quality of links between them. Furthermore, three different metrics for next hop selection is introduced enabling nodes to select their next hop forwarders more sophisticatedly using quality of links, geographical location of nodes, and their trust level. Extensive simulation results represent that proposed model can significantly improve the performance of network communications when malicious nodes try to collapse the system.

Toward a Comprehensive Model for Performance Analysis of Opportunistic Routing in Wireless Mesh Networks

Opportunistic routing (OR) is a promising paradigm that has been proposed for wireless mesh networks. This routing paradigm takes advantage of the broadcast nature of the wireless medium to increase the reliability of transmissions in multihop wireless networks. The selection of a set of candidates involves satisfying the basic requirements of the model, in which packets are forwarded toward the destination. In OR, if one of the selected candidates does not receive the packet, another candidate might be able to continue forwarding the packet. The decision of which forwarder to choose is made by coordination between candidates that have successfully received the transmitted packet. In this paper, we propose a discrete-time Markov chain as a general model for OR and demonstrate how it can be used to evaluate the performance of OR protocols. We also review three well-known OR protocols that we have selected as a study case. Our study demonstrates how our model facilitates better understanding of the combination of a number of candidates and retransmissions and their significant contributions to the successful delivery of data packets. Thus, this shows that our model can help in the design of future OR protocols and efficient candidate selection algorithms.

Modeling and performance evaluation of security attacks on opportunistic routing protocols for multihop wireless networks

In wireless networks, opportunistic routing (OR) protocols are designed to route data packets towards their destination with greater reliability than traditional routing schemes. In addition to reliability, nodes trustworthiness and willingness to cooperate can also play a significant role in the delivery of packets to their final destinations. More specifically, nodes in the network may be compromised, experience software or hardware failures, or behave maliciously for various reasons. Therefore, it would be beneficial to model the behavior of malicious or uncooperative nodes and study their effects in a wireless network that employs OR for communications. In this paper, the behavior of malicious nodes in a wireless mesh network that utilizes unicast opportunistic routing protocols is modeled using Discrete Time Markov Chain (DTMC). Afterwards, using the proposed model, we introduce a novel approach for the calculation of packet drop ratio, through which the negative effects of uncooperative nodes can be calculated. Furthermore, a customized version of a black-hole attack is introduced as an example of malicious behavior in OR protocols; we apply this routing attack to several well-known OR protocols, with the additional use of network simulation as well as through the proposed analytical technique. Finally, a comprehensive set of performance evaluation scenarios is designed and applied, with the purpose of investigating the effects of different parameters on a wireless mesh network that uses OR as a routing approach in the presence of malicious nodes. Evaluation results indicate that the proposed black-hole attack can significantly downgrade communication performance, and the proposed model can properly model the effects of malicious nodes on OR protocols.

Opportunistic routing protocols in wireless networks: A performance comparison

The broadcast nature of the wireless medium applied in Opportunistic Routing (OR) to improve the performance of wireless networks. OR protocols select a set of candidates as the next-hop forwarder. Each candidate can act as a potential forwarder if it receives the packet. Candidate selection is one of the main issues for OR protocols. In this paper, we implement and compare different ranges of OR protocols (simple, complex and optimum ones) in terms of different performance parameters using NS-2. The obtained results through extensive simulations show that OR improves the performance of network in different terms. Furthermore, our results provide insights to the use of each opportunistic routing protocols in different scenarios.

Mobility-based opportunistic routing for mobile ad-hoc networks

Opportunistic Routing (OR) is an effective and enhanced routing scheme for wireless multihop environment. OR is an approach which selects a certain number of best forwarders (candidates) at each hop by taking the advantage of the broadcast nature of the wireless medium to reach the destination. When a set of candidates receive the packet, they coordinate with each other to figure out which one has to forward the packet toward the destination. Most of the researches in this area have been done in mesh networks where nodes do not have mobility. In this paper, we propose a new OR protocol for mobile ad hoc scenarios called as Enhanced Mobility-based Opportunistic Routing (EMOR) protocol. To deal with the node mobility, we have proposed a new metric which considers the geographical position of the candidates, the link delivery probability to reach them, the number of the neighboring nodes of the candidate, and the predicted position of nodes using the motion vector of the nodes. We have compared EMOR with five other well-known routing protocols in terms of delivery ratio, end-to-end delay, and expected number of transmissions from source to the destination. Our simulation results show that proposed protocol improves delivery ratio and number of expected transmission in terms of different type of mobility models.

On the Effect of Black-hole Attack on Opportunistic Routing Protocols

Black-hole is a well-known routing attack through which malicious nodes try to downgrade the communication performance of wireless networks. On the other hand, opportunistic routing protocols aim to increase the reliability of communications compared to traditional routing approaches by utilizing the broadcast nature of wireless medium. Although a tremendous amount of research has been performed in the literature to detect and cancel the effect of black-hole nodes for traditional routing protocols, it is of high importance to study the effects of such a significant security obstacle for opportunistic routing methods as well. In this paper, an analytical model is proposed using Markov chains to model the effect of black-hole attack on opportunistic routing protocols. Furthermore, a novel version of the black-hole attack is proposed and customized for opportunistic routing approaches. Finally, the consequences of this attack on delivering packets to their destination are evaluated, compared, and discussed using both analytical and simulation-based methods. Conducted analyses demonstrate that the proposed attack can have devastating effects on the networks performance.

Modeling and Analysis of Opportunistic Routing in Multi-hop Wireless Networks

Opportunistic Routing (OR) takes advantage of the broadcast nature of the wireless medium to increase reliability in communications. Instead of selecting one node as the next-hop forwarder, OR selects a set of candidates to forward the packet. In this way, if one of them does not receive the packet from the source, another candidate will be able to do it, this avoids the need for a re-transmission from the source. To increase the successful delivery ratio, we can increase the size of the candidate set or the number of re-transmissions, but, we must take into account the impact on the use of the network resources. In this paper, we propose a Markov chain as a general model for OR that can be applied to any kind of network topology and any candidate selection algorithm without any constraint. The only input parameters needed are: i) the candidate list of each node, ii) the link delivery probability between nodes, and, iii) the maximum number of re-transmissions in each node. Taking this data into account, our model allows for the evaluation of the performance of different candidate selection algorithms according to different metrics, such as the expected number of transmissions (ExNT), which is one of the most relevant metrics in OR. Our model also enables an evaluation of the influence of the number of candidates, its relation to the number of re-transmissions and how these two parameters together contribute to the successful delivery of data packets.