Opportunistic Routing Algorithm Research Articles

Opportunistic Routing Algorithm for Relay Node Selection in Wireless Sensor Networks

Energy savings optimization becomes one of the major concerns in the wireless sensor network (WSN) routing protocol design, due to the fact that most sensor nodes are equipped with the limited nonrechargeable battery power. In this paper, we focus on minimizing energy consumption and maximizing network lifetime for data relay in one-dimensional (1-D) queue network. Following the principle of opportunistic routing theory, multihop relay decision to optimize the network energy efficiency is made based on the differences among sensor nodes, in terms of both their distance to sink and the residual energy of each other. Specifically, an Energy Saving via Opportunistic Routing (ENS_OR) algorithm is designed to ensure minimum power cost during data relay and protect the nodes with relatively low residual energy. Extensive simulations and real testbed results show that the proposed solution ENS_OR can significantly improve the network performance on energy saving and wireless connectivity in comparison with other existing WSN routing schemes.

Dynamic Rendezvous Based Routing Algorithm on Sparse Opportunistic Network Environment

An opportunistic network is a network where the nodes need to communicate with each other even if existing routes between them may not permanently exist due to the nodes’ random movement. Most routing algorithms employ a paradigm by which a node can keep the receiving messages, carrying the messages with them when moving and then forwarding the messages to the opportunistic meeting nodes when possible. This routing model works well in the networks with high-to-moderate node density in which the opportunity that the moving nodes can meet with each other is rather high. On the other hand, the delivery ratio becomes remarkably low in the sparse network environment especially when there is a strict constraint on message delivery deadline. In this paper, we introduce the novel concept of rendezvous place where the passing nodes can announce, deposit, or pick up their own messages without having to meet the other nodes carrying the desired message. The rendezvous place can be detected automatically and its area's shape is dynamically changed according to the interaction among nodes. The results from extensive simulations show that our routing algorithm can achieve higher delivery ratio and utilize lower energy consumption than traditional opportunistic routing algorithms especially in sparse network environment.

Five Decades of Hierarchical Modulation and Its Benefits in Relay-Aided Networking

Hierarchical modulation (HM), which is also known as layered modulation, has been widely adopted across the telecommunication industry. Its strict backward compatibility with single-layer modems and its low complexity facilitate the seamless upgrading of wireless communication services. The specific features of HM may be conveniently exploited for improving the throughput/information-rate of the system without requiring any extra bandwidth, while its complexity may even be lower than that of the equivalent system relying on conventional modulation schemes. As a recent research trend, the potential employment of HM in the context of cooperative communications has also attracted substantial research interests. Motivated by the lower complexity and higher flexibility of HM, we provide a comprehensive survey and conclude with a range of promising future research directions. Our contribution is the conception of a new cooperative communication paradigm relying on turbo trellis-coded modulation-aided twin-layer HM-16QAM and the analytical performance investigation of a four-node cooperative communication network employing a novel opportunistic routing algorithm. The specific performance characteristics evaluated include the distribution of delay, the outage probability, the transmit power of each node, the average packet power consumption, and the system throughput. The simulation results have demonstrated that when transmitting the packets formed by layered modulated symbol streams, our opportunistic routing algorithm is capable of reducing the transmit power required for each node in the network compared with that of the system using the traditional opportunistic routing algorithm. We have also illustrated that the minimum packet power consumption of our system using our opportunistic routing algorithm is also lower than that of the system using the traditional opportunistic routing algorithm.

Mobility Models, Traces and Impact of Mobility on Opportunistic Routing Algorithms: A Survey

Mobile Opportunistic Network (MON) is characterized by intermittent connectivity where communication largely depends on the mobility pattern of the participating nodes. In MON, a node can take the custody of a packet for a long time and carry it until a new forwarding path has been established, unlike mobile adhoc network (MANET), where a node must drop the packet otherwise. Therefore, routing in MON depends on the repeated make-and-break of communication links, which again depends on the mobility of the nodes as they encounter and drift away from each other. MONs can simply be formed by humans carrying hand-held devices (like Personal Digital Assistant [PDAs] or cell phones) or on-board devices installed in vehicles. Therefore, with mobility playing a major role in the performance of MON, researchers have repeatedly tried to understand the nature of mobility with respect to humans, vehicles, and wild animals. To study the nature of mobility, researchers have collected mobility traces, proposed mobility models, and analyzed the performance of MON with respect to various mobility parameters. This article provides a detailed survey of different mobility models which have been proposed to date and how mobility largely determines the performance of opportunistic routing. We divide the article into four major sections. First, we provide a detailed survey of all the synthetic mobility models which have been developed to date. Second, we study the various mobility traces which have been collected and analyzed. Third, we study how mobility parameters affect the performance of MON. Finally, we highlight on some of the research areas and open challenges which yet remain unsolved.

Reliable Transport in Delay-Tolerant Networks With Opportunistic Routing

This paper tackles the issue of reliable transport in delay-tolerant mobile ad hoc networks (DTNs) that are operated by some opportunistic routing algorithm. We propose a reliable transport mechanism that relies on acknowledgements (ACKs) and coding at the source. The various versions of the problem depending on buffer management policies are formulated and a fluid model based on mean-field approximation is derived for the designed reliable transport mechanism. This model allows both the mean file completion time and the energy consumption to be expressed up to the delivery of the last ACK at the source. The accuracy of this model is assessed through numerical simulations and a detailed investigation of the impact of the system parameters on the performance is conducted. We eventually present a joint optimization of the mean completion delay with or without an energy constraint, to identify the optimal set of parameters to use.

Community-Aware Opportunistic Routing in Mobile Social Networks

Mobile social networks (MSNs) are a kind of delay tolerant network that consists of lots of mobile nodes with social characteristics. Recently, many social-aware algorithms have been proposed to address routing problems in MSNs. However, these algorithms tend to forward messages to the nodes with locally optimal social characteristics, and thus cannot achieve the optimal performance. In this paper, we propose a distributed optimal Community-Aware Opportunistic Routing (CAOR) algorithm. Our main contributions are that we propose a home-aware community model, whereby we turn an MSN into a network that only includes community homes. We prove that, in the network of community homes, we can still compute the minimum expected delivery delays of nodes through a reverse Dijkstra algorithm and achieve the optimal opportunistic routing performance. Since the number of communities is far less than the number of nodes in magnitude, the computational cost and maintenance cost of contact information are greatly reduced. We demonstrate how our algorithm significantly outperforms the previous ones through extensive simulations, based on a real MSN trace and a synthetic MSN trace.

Research on Robustness of Typically Opportunistic Network Routing Algorithm under Flooding Attack

This paper designed the evaluation method and the index system. Through simulating behavior of pedestrian with mobile intelligent Bluetooth devices in the real city scene and did a quantitative analysis about the effects of flooding attacks to opportunity network in the three aspects of transmission capacity, transmission efficiency and energy consumption of nodes , in order to evaluate Direct Delivery, Spray and Wait and MaxProp the three opportunity network routing algorithm’s robustness under the flooding attack results showed that Direct Deliven algorithm robustness is best, it can withstand flooding attacks completely, robustness of the Spray and Wait algorithm is the worst, their performance will decline more than 80% in some scenarios, the performance of MaxProp algorithm under flood attacks will decrease remarkably.

Opportunistic Routing Algorithm Based on Topological Time-varying and Residual-energy Balance in Wireless Sensor Network

为了解决数据报文在无线传感网络中动态路由以及网络内各节点剩余能量均衡问题，该文提出了一种机会路由算法。首先，利用热力学第2定律描述数据报文在无线传感器网络中动态路由的传输过程，其中，为了表征网络内各节点状态的时变性以及剩余能量，提出了机会熵模型；其次，以机会熵模型作为选择下一跳节点的理论依据，并结合蚁群优化(ACO)算法，设计并实现了考虑网络中各节点时变性与剩余能量均衡的机会路由算法(ACO for Time Dependent Opportunistic-routing Protocol, ATDOP)，使得数据报文在转发过程时，能够有效地选择下一跳节点，从而使网络内各节点的通信资源和能量资源达到负载均衡。最后，通过实验证明，相对于已有的机会路由协议，ATDOP具有报文成功传输率高、网络有效吞吐量大以及网络工作寿命长等优点。

Opportunistic Routing in Intermittently Connected Mobile P2P Networks

Mobile P2P networking is an enabling technology for mobile devices to self-organize in an unstructured style and communicate in a peer-to-peer fashion. Due to user mobility and/or the unrestricted switching on/off of the mobile devices, links are intermittently connected and end-to-end paths may not exist, causing routing a very challenging problem. Moreover, the limited wireless spectrum and device resources together with the rapidly growing number of portable devices and amount of transmitted data make routing even harder. To tackle these challenges, the routing algorithms must be scalable, distributed, and light-weighted. Nevertheless, existing approaches usually cannot simultaneously satisfy all these three requirements. In this paper, we propose two opportunistic routing algorithms for intermittently connected mobile P2P networks, which exploit the spatial locality, spatial regularity, and activity heterogeneity of human mobility to select relays. The first algorithm employs a depth-search approach to diffuse the data towards the destination. The second one adopts a depth-width-search approach in a sense that it diffuses the data not only towards the destination but also to other directions determined by the actively moving nodes (activists) to find better relays. We perform both theoretical analysis as well as a comparison based simulation study. Our results obtained from both the synthetic data and the real world traces reveal that the proposed algorithms outperform the state-of-the-art in terms of delivery latency and delivery ratio.

Moving Target Oriented Opportunistic Routing Algorithm in Vehicular Networks

In vehicular networks, the multihop message delivery from information source to moving vehicles presents a challenging task due to many factors, including high mobility, frequent disconnection, and real-time requirement for applications. In this paper, we propose a moving target oriented opportunistic routing algorithm in vehicular networks for message delivery from information source to a moving target vehicle. In order to adapt the constantly changing topology of networks, the forwarding decisions are made locally by each intermediate vehicle based on the trajectory information of the target vehicle. The simulation and real trace experiment show that our design provides an efficient message delivery with a higher success ratio, shorter success time, and lower transmission overhead compared with other reference approaches.

Domain-epidemic spray and forward routing algorithm of opportunistic networks

For the current opportunistic networks routing algorithms, their message arrival rate is not high and the delivery delay is large. This paper proposes a domain-epidemic spray and forward routing algorithm. The algorithm integrates redundancy and encounter prediction strategy. According to the probability of encounters between nodes, the nodes are divided into different domains. The spray and forward strategy is used between domains and the epidemic strategy is used to forward messages within a domain. Using the message confirmation mechanism and a list which is used to record the messages that have arrived to their destination, the new algorithm can effectively reduce redundant messages. Simulation results show our algorithm can effectively improve message arrival rate and reduce end-to-end delay to some extent.

Social-awareness in opportunistic networking

Since uninterrupted connectivity has become such an important part of everyday life, the amount of energy consumed by the various devices used has increased considerably. We propose a way to limit this consumption by employing opportunistic networks, which are mainly composed of mobile devices that have no need for a static network infrastructure. They communicate when in range, using a store-carry-and-forward paradigm. We believe that opportunistic networks can be deployed in closed environments if there is a certainty that messages sent in the network eventually reach their destination. Therefore, we propose the addition of social data to existing opportunistic routing algorithms. We investigate our approach using two traces collected in different environments and we present an analysis of our findings. Most importantly, we show that by adding knowledge such as social links between participants, the performance of the opportunistic network can be improved.

Benefiting from the community structure in opportunistic forwarding

In Delay Tolerant Networks (DTNs), an end-to-end connectivity cannot be assumed for node mobility and lack of infrastructure. Due to the uncertainty in nodal mobility, routing in DTNs becomes a challenging problem. To cope with this, many researchers proposed opportunistic routing algorithms based on some utilities. However, these simple metrics may only capture one facet of the single node?s mobility process, which cannot reflect the inherent structure of the networks well. Recently, some researchers introduce the Complex network analysis (CNA) to formulate and predict the future contact in DTNs. The community structure is one of the most important properties of CNA. And it reveals the inherent structure of the complex network. In this paper, we present a community-based single-copy forwarding protocol for DTNs routing, which efficiently utilizes the community structure to improve the forwarding efficiency. Simulation results are presented to support the effectiveness of our scheme.

An Improved Spray and Wait with Probability Choice Routing for Opportunistic Networks

Opportunistic networks are sparse multi-hop ad hoc networks in which nodes exploit any pair-wise contact opportunities to share and forward messages. The main challenge for this environment is that conventional routing schemes do not work properly. Among the existing Opportunistic Networks routing algorithms, the epidemic routing and probabilistic routing could provide higher delivery probability and shorter delays, but is with a large overhead, while the spay and wait routing could reduce the overhead, but is with low delivery probability and high delay. This paper proposes the Spray and Wait with Probability Choice (SWPC) routing, where continuous encounter time is used to describe the encounter opportunity; a delivery probability function is set up to direct the different number of copies to the destination during the spray phase; and a forwarding scheme is implemented in the wait phase. Simulation results show that proposed SWPC shows prominent superiority in the delivery rate, the average delay and the communication overhead, and adapted for the frequently disconnected opportunistic network.

Diversity of multi-hop cluster-based routing with arbitrary relay selection

Clustered multi-hop wireless networks have attracted significant attention for their robustness to fading, hierarchical structure, and ability to exploit the broadcast nature of the wireless channel. The authors propose an opportunistic routing (or relay selection) algorithm for such networks. In contrast to the majority of existing approaches to routing in clustered networks, the algorithm presented in this study only requires channel state information in the final hop, which is shown to be crucial for reaping the diversity offered by the channel. In addition to exploiting the available diversity, our simple cross-layer algorithm has the flexibility to simultaneously satisfy an additional routing objective such as the maximisation of network lifetime. The authors demonstrate through analysis and simulation that our proposed routing algorithm attains full diversity under certain conditions on the cluster sizes, and its diversity is equal to the diversity of more complicated approaches that require full channel state information.

Simple, Practical, and Effective Opportunistic Routing for Short-Haul Multi-Hop Wireless Networks

In this paper, we propose a simple and practical opportunistic routing algorithm, and we analyze its performance along a multi-hop wireless network path, while considering link-level interference among the network nodes. Through our analysis, we show that our algorithm results in significant improvement in throughput, especially for short-haul paths. The proposed algorithm can be easily integrated into most routing protocols with only minor modifications. Consequently, the algorithm provides a practical and effective approach for implementation of opportunistic routing in wireless networks.

Minimum-Energy Cooperative Routing in Wireless Networks with Channel Variations

This paper considers the problem of finding minimum-energy cooperative routes in a wireless network with variable wireless channels. We assume that each node in the network is equipped with a single omnidirectional antenna and, motivated by the large body of physical layer research indicating its potential utility, that multiple nodes are able to coordinate their transmissions at the physical layer in order to take advantage of spatial diversity. Such coordination, however, is intrinsically intertwined with routing decisions, thus motivating the work. We first formulate the energy cost of forming a cooperative link between two nodes based on a two-stage transmission strategy assuming that only statistical knowledge about channels is available. Utilizing the link cost formulation, we show that optimal static routes in a network can be computed by running Dijkstra's algorithm over an extended network graph created by cooperative links. However, due to the variability of wireless channels, we argue that a many-to-one cooperation model in static routing is suboptimal. Hence, we develop an opportunistic routing algorithm based on many-to-many cooperation, and show that optimal routes in a network can be computed by a stochastic version of the Bellman-Ford algorithm. We use static and opportunistic optimal algorithms as baselines to develop heuristic link selection algorithms that are energy efficient while being computationally simpler than the optimal algorithms. We simulate our algorithms and show that while optimal cooperation and link selection can reduce energy consumption by almost an order of magnitude compared to non-cooperative approaches, our simple heuristics achieve similar energy savings while being computationally efficient as well.

Testbed results of an opportunistic routing for multi-robot wireless networks

Opportunistic routing is a candidate for multihop wireless routing where the network topology and radio channels vary rapidly. However, there are not many opportunistic routing algorithms that can be implemented in a real multihop wireless network while exploiting the node mobility. It motivates us to implement an opportunistic routing, random basketball routing (BR), in a real multi-robot network to see if it can enhance the capacity of the multihop network as mobility increases. For implementation purposes, we added some features, such as destination RSSI measuring, a loop-free procedure and distributed relay probability updating, to the original BR. We carried out the experiments on a real multi-robot network and compared BR with AODV combined with CSMA/CA (routing + MAC protocol). We considered both static and dynamic scenarios. Our experiments are encouraging in that BR outperforms AODV + CSMA/CA, particularly in dynamic cases; the throughput of BR is 6.6 times higher than that of AODV + CSMA/CA. BR with dynamic networks shows 1.4 times higher throughput performance than BR with static networks. We investigate the performance of BR in the large-scale network using NS-2 simulation. We verify the effect of node density, speed, destination beacon signal and loop-free procedure. According to the large-scale simulation, the end-to-end throughput grows with the node speed.

On the Capacity of Hybrid Wireless Networks with Opportunistic Routing

This paper studies the capacity of hybrid wireless networks with opportunistic routing (OR). We first extend the opportunistic routing algorithm to exploit high-speed data transmissions in infrastructure network through base stations. We then develop linear programming models to calculate the end-to-end throughput bounds from multiple source nodes to single as well as multiple destination nodes. The developed models are applied to study several hybrid wireless network examples. Through case studies, we investigate several factors that have significant impacts on the hybrid wireless network capacity under opportunistic routing, such as node transmission range, density and distribution pattern of base stations (BTs), and number of wireless channels on wireless nodes and base stations. Our numerical results demonstrate that opportunistic routing could achieve much higher throughput on both ad hoc and hybrid networks than traditional unicast routing (UR). Moreover, opportunistic routing can efficiently utilize base stations and achieve significantly higher throughput gains in hybrid wireless networks than in pure ad hoc networks especially with multiple-channel base stations.