Performance evaluation of replication-based DTN routing protocols in Intermittently Connected Mobile Networks

Delay-Tolerant Networks (DTNs) are kinds of networks where there does not exist any complete end-to-end route from source to destination. Such networks can also be referred to as Intermittently Connected Mobile Networks (ICMNs), which are featured by asymmetric data rates, large delay, limited resources and high error rates. In this network, size of buffer and Time-to-Live (TTL) for fixed number of nodes and message generation rates contribute to the network performance because of limited resources and short life span of a packet in the net-work. Therefore, investigating efficient routing for altering TTL and size of buffer is very important for overall network performance. This paper presents a performance analysis based on simulation of the impact of buffer size and TTL for several DTN routing protocols in ICMNs scenario. ONE, i.e., Opportunistic Network Environment is used to simulate the routing protocols considering three performance metrics: delivery ratio, mean latency and overhead ratio. Investigated results mention that Spray-and-Focus (SNF) routing exhibits the best performance for altering TTL and size of buffer than other DTN routing protocols, i.e., Epidemic, PRoPHET, PRoPHETv2, MaxProp, RAPID, and Binary-SNW in the considered performance metrics and simulation scenario.

Usage of wireless gadgets is increasing day by day in both metropolitan and countryside localities. The network infrastructure does not reach all the localities; especially in rural areas, where the internet availability is inadequate to meet the network requirements. Devices in such rural locations will be out of the network for some period. This non-persistent connectivity problem can be solved by using the moving nodes as a carrier for data transmission. In this work, we classify the vehicular network into sparse, semi-sparse and dense network based on the number of static and moving nodes present in a location. In sparse and semi-sparse network, there won't be any continuous path between the source and destination nodes. In such networks, we can use Delay Tolerant Network (DTN) protocols for data transmission. In our work, we try to find the suitable DTN protocol for the sparse and semi-sparse network topology. The protocols considered in this work are Epidemic, Spray and Wait, and Maxprop and the parameters we analyzed are delivery ratio, average latency and overhead ratio. We simulated these protocols in a vehicular network with heterogeneous characteristics, for the dense, semi-sparse and sparse network topology. The routing protocols performance is analyzed by delivery ratio, average latency and overhead ratio using Opportunistic Network Environment (ONE) simulator for varying the message lifetime and node density.

In recent years, several investigations have been made on "challenged network" [also known as, delay tolerant network (DTN)] architectures highlighting their advantages and disadvantages. In spite of its inherent shortcomings of unreliability and delay, smart-phone based opportunistic network is gaining immense popularity in the research community due to its applicability in different adverse and extreme communication scenarios where traditional communication infrastructure is either unavailable or incapacitated for a long time. Considerable research has been conducted till date to design efficient network architecture for emergency data dissemination in intermittently connected/challenged networks. Different architectures (ranging from flat to multi-tier) are proposed for implementing opportunistic DTN keeping in view of specific application requirements. However, very few of these proposed architectures have been examined from the perspective of a post disaster communication. Moreover, most DTN architectures are designed by aiming towards increasing delivery probability and reducing latency and as a whole, maximizing network throughput; with very little emphasis on its energy efficiency. The impact of different mobility patterns on existing DTN routing algorithms with respect to data dissemination and energy consumption has also not been studied so far. Our objective, in this paper, is to investigate the impact of different mobility patterns on existing DTN routing protocols and existing DTN architectures and subsequently, come up with a suitable energy efficient DTN framework combining suitable architecture and routing protocol that may be used to offer different disaster management services during post-disaster relief operation. We have done an extensive simulation on ONE simulator with different categories of well-known existing DTN architectures, mobility models, DTN routing protocols to study the network performance in terms of delivery probability, energy efficiency and overhead ratio. Based on the simulation results, we have tried to figure out a suitable combination of energy efficient architecture, mobility model and routing protocol that fits well in the post disaster communication scenario.

Networks that lack continuous connectivity among their nodes due to node mobility, limited data storage space and constrained power sources are called Delay Tolerant Networks (DTNs). DTN nodes store and carry the data packets until they come into the communication range of each other. In recent years several protocols have been developed specifically for routing in DTNs. These protocols vary in number of copies they use and the kind and amount of knowledge they use to guide the packets to their destinations. Remaining energy level, average latency, overhead ratio and delivery ratio are some of the performance metrics used to measure the performance of these protocols. The existing protocols are good in some of these metrics but not all of them. There is always a trade-off between different performance metrics. In this paper we have proposed a Hybrid protocol utilizing advantages of two protocols namely Epidemic and Probabilistic Routing. The performance is discussed and compared of these protocols with our Hybrid strategy in Opportunistic Network Environment tool.

In this paper, we evaluate and compare the performance of single-copy and multiple-copy routing protocols in a realistic Vehicular Delay Tolerant Network (VDTN) scenario. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. The performance is analyzed using delivery probability, overhead ratio, average latency, average number of hops and average buffer time metrics. The simulation results show that multiple-copy protocols perform better in terms of delivery probability compared with singlecopy protocol. The single-copy protocol uses the highest average number of hops and higher average latency compared with multiple-copy protocols. Maxprop achieves the highest delivery ratio and lowest average latency. Spray and wait results are the lowest for overhead ratio, but the longest for average buffer time. First contact have a short buffer time, but it uses a big number of hops.

Majority of the existing Delay Tolerant Network (DTN) routing protocols, attempt to minimize one of the popular DTN routing indices, i.e. message delay, forwarding count and storage. However, for many DTN applications such as distributing commercial content, targeting the best performance for one index and compromising the others is insufficient. A more practical solution would be to strike a balance between multiple of these indices. Gain Dissemination Protocol (GDP) is one of the protocols which targets this aim by introducing a gain concept which tries reach a maximum gain of delivery by keeping the balance between the value achieved via delivering the packet to the destination and the forwarding cost involved with that. In this paper, we focus on characterizing the GDP protocol in the scope of mobility. We also propose an upper bound for gain in multicast routing problem, i.e. the Union of Unicast Benchmark (UUB) and compare the performance of a few DTN routing protocols with the former. This eventually reveals the performance scope of a potential gain-aware DTN dissemination protocol.

A taxonomy on misbehaving nodes in delay tolerant networks

Delay Tolerant Network (DTN) is a sparse and intermittently connected mobile wireless network where reliable communication and end-to-end connectivity cannot be assured. In DTN, a node delivers messages to the destination using store and forward scheme. Messages are copied and transferred to multiple relay-nodes in order to increase the opportunity for that message to reach the intended destination. Contact is the time duration for which two or more mobile nodes encounter each other within their radio transmission ranges, and are able to transfer messages. Due to arbitrary node movement, contact time will be varied, and is unlikely to be predictable. In this paper, we propose a fuzzy decision mechanism we called “fuzzy-spray”, to improve the routing and packet transfer efficiency in DTN environment. Fuzzy-spray can reduce overall latency in DTN by intelligently selecting appropriate messages to send to the relay-node during its next contact time. It uses fuzzy logic to prioritize messages that are stored in the buffer, based only on local parameters from each message, namely forward transmission count and message size. There is no need to know a priori information about network such as node mobility model, or node-distribution across the deployed area. The simulation results show that fuzzy-spray has the best performance in terms of overall speed of delivery, and lowest average message delay compared with other existing algorithms.

There is a growing need for secure and robust networks that function in austere environments or with nodes that have limited resources. The prime example is Delay Tolerant Networks that have military, first response, infrastructure failure and vehicle applications. This class of networks requires the modification of traditional routing and security protocols, such as TCP/IP or the use of certificate revocation servers, to effectively transmit a message from source to destination in a secure manner. There are multiple trust and routing schemes proposed for use in Delay Tolerant Networks. Here, we show how trust, usually defined in the context of network science, can be utilized for routing in Delay Tolerant Networks in which the fundamental challenge is balancing energy, delivery rate, delivery delay and security. Trust is a cornerstone of our approach to address this challenge. We propose a Trust Based Secure Routing Protocol, in which forwarding decisions are based on nodes trust, expected destination meeting time and the number of already created copies of the message.

The Opportunistic Networking Environment (ONE) Simulator is an extensible tool for evaluating protocols and mobility models for delay-tolerant networking. ONE allows easily plugging in mobility models, contact traces, routing modules, applications, and report modules. In this paper, we describe how to instrument the ONE simulator for two content sharing applications: spreading content in waves across mostly stationary nodes and geo-based content sharing between mobile nodes using Floating Content. Both are included in the ONE simulator version 1.5.1.

Anycast routing is very useful for many applications such as resource discovery in delay tolerant networks (DTNs). In this paper, based on a new DTN model, we first analyze the any-cast semantics for DTNs. Then we present a novel metric named EMDDA (expected multi-destination delay for anycast) and a corresponding routing algorithm for anycast routing in DTNs. Extensive simulation results show that the proposed EMDDA routing scheme can effectively improve the efficiency of anycast routing in DTNs. It outperforms another algorithm, minimum expected delay (MED) algorithm, by 11.3% on average in term of routing delays and by 19.2% in term of average max queue length.

Today’s network becomes more complex due to which performances of network decrease like message delivery ratio, overhead ratio, average latency, cost, etc. A new technique comes to forward the message on the basis of social infrastructure. In this paper, we analyze and compare the result of social-based opportunistic routing protocol with different mobility traces, and we compare the BubbleRap, DLife (daily life routine routing algorithm) and dLifeComm (daily life routine community-based routing algorithm) social routing protocol with different movement models and real traces with respect to delivery ratio, overhead ratio, and average latency. Comparison is based on the real human traces and synthetic mobility model. We use Opportunistic Network Environment (ONE) simulator for result analysis. As from the simulation result, delivery ratio of BubbleRap is better than DLife and dLifeComm when node follows the community-based movement.

Previous Delay Tolerant Network (DTN) routing algorithms exploit either past encounter records (probabilistic routing) or social network properties (social network based routing) to derive a node's probability of delivering packets to their destinations. However, they only have a local view of the network, which limits the routing efficiency. Also, when two nodes meet, they have to exchange the delivery probabilities to the destinations of all packets in the two nodes, which incurs high resource consumption. In a social network, the people a person frequently meets are usually stable, which makes them play a more important role in forwarding message for the person. Based on this, we propose a lightweight distributed Social MAp based Routing algorithm in delay Tolerant networks (SMART). In SMART, each node builds its own social map consisting of nodes it has met and their frequently encountered nodes in a distributed manner. Based on both encountering frequency and social closeness of the two linked nodes in the social map, we decide the weight of each link to reflect the packet delivery probability between the two nodes. The social map enables more accurate forwarder selection through a broader view. Moreover, nodes exchange much less information for social map update and need fewer updates due to social map stability, which reduces resource consumption. Trace-driven experiments and tests on the GENI ORBIT testbed demonstrate the high efficiency of SMART in comparison with previous algorithms.

Disruption-tolerant networks (DTNs) are groups of network assets connected with a suite of communication protocol technologies designed to mitigate the effects of link delay and disruption. Application of DTN protocols to diverse groups of network resources in multiple sub-networks results in an overlay network-of-networks with autonomous data routing capability. In space environments where delay or disruption is expected, performance of this type of architecture (such as an interplanetary internet) can increase with the inclusion of new communications mediums and techniques. Space-based optical communication links are therefore an excellent building block of space DTN architectures. When compared to traditional radio frequency (RF) communications, optical systems can provide extremely power-efficient and high bandwidth links bridging sub-networks. Because optical links are more susceptible to link disruption and experience the same light-speed delays as RF, optical-enabled DTN architectures can lessen potential drawbacks and maintain the benefits of autonomous optical communications over deep space distances. These environment-driven expectations - link delay and interruption, along with asymmetric data rates - are the purpose of the proof-of-concept experiment outlined herein. In recognizing the potential of these two technologies, we report an initial experiment and characterization of the performance of a DTN-enabled space optical link. The experiment design employs a point-to-point free-space optical link configured to have asymmetric bandwidth. This link connects two networked systems running a DTN protocol implementation designed and written at JPL for use on spacecraft, and further configured for higher bandwidth performance. Comparing baseline data transmission metrics with and without periodic optical link interruptions, the experiment confirmed the DTN protocols' ability to handle real-world unexpected link outages while maintaining capability of reliably delivering data at relatively high rates. Finally, performance characterizations from this data suggest performance optimizations to configuration and protocols for future optical-specific DTN space link scenarios.

Generic prediction assisted single-copy routing in underwater delay tolerant sensor networks