Asanga Udugama

Universität Bremen | Uni Bremen · Sustainable Communication Networks

In this chapter, we explore how the mobility of nodes influences the performance of opportunistic networks. First, we start with a general discussion of how scale and density are defined and how those impact the dissemination of data in opportunistic networks. Then, we dive deeper into how to gather realistic mobility data from real-world scenarios...

Security is of paramount importance in Opportunistic Networks (OppNets) due to its unique characteristics and operational challenges. OppNets are designed for environments with intermittent or disrupted connectivity such as disaster recovery. In such scenarios, traditional end-to-end communication models may not be feasible, making OppNets a crucia...

In this chapter, we discuss the challenges when comparing different opportunistic solutions (mostly forwarding protocols, but the discussion can be easily applied to any opportunistic services). We will look into what benchmarks are in general, which benchmarks exist for opportunistic networks, and how to use and interpret their results.

Data dissemination is the main research and implementation challenge in opportunistic networks. It addresses the question of how to forward data in a resource-efficient but also fast way. The main concept is called store-carry-forward, which means that nodes forward the data to other nodes, which carry it around until finding a better forwarder or...

Infrastructure‐less networks connect communication devices end‐to‐end by managing links and routes independent of fixed networking facilities, relying on dedicated protocols running on end‐user devices. The large variety of infrastructure‐less concepts and related aspects can be confusing both for beginning Ph.D. students as well as experienced res...

Today's networks are used primarily to move content. To cater to this requirement Information Centric Networks (ICN) were introduced. One of the main architectures of ICN is Content Centric Networking (CCN) and its derivative, Named Data Networking (NDN). CCN is standardized at the Internet Engineering Task Force (IETF) and is envisaged to replace...

In this paper, we present our experience with redesigning an introductory computer science course for (electrical) engineers with blended learning concepts. It is a large mandatory course with eight credit points over the course of two semesters, where first year electrical engineers learn how to program with Arduino, C and Python. Additionally, th...

In this white paper, we share our experience with a first year Masters course preparation and implementation during the Corona semester in summer 2020. The main challenge of this course was to deal with students, who have been accepted for graduate studies at the Masters level at the University of Bremen, Germany, but did not arrive in Germany on t...

Wireless communication is essential for autonomous underwater vehicles (AUVs) in order to provide job instructions, forward sensed data or coordinate multiple AUVs working in a swarm. However, communication in the underwater environment is unreliable and does not allow high data rates due to high interference and poor signal propagation conditions....

Opportunistic networks enables the devices to communicate as and when the opportunity rises. This property of OppNets has been explored in routing approaches in a similar operating manner as the traditional infrastructure networks. Specifically, context-aware routing approaches have been the major focus of OppNets in the recent literature. However,...

In this chapter, we focus on how to simulate Opportunistic Networks (OppNets) in OMNeT++. After defining what OppNets are and how they are different from other networking concepts, we detail, one by one, the necessary models for simulating them, such as mobility, network traffic, user behavior, and communication models focusing on the framework tha...

A variety of applications and forwarding protocols have been proposed for opportunistic networks (OppNets) in the literature. However, the methodology of evaluation, testing and comparing these forwarding protocols are not standardized yet, which leads to large levels of ambiguity in performance evaluation studies. Performance results depend largel...

Opportunistic networks have recently seen increasing interest in the networking community. They can serve a range of application scenarios, most of them being destination-less, i.e., without a-priori knowledge of who is the final destination of a message. In this paper, we explore the usage of data popularity for improving the efficiency of data fo...

These are the proceedings of the 5th International OMNeT++ Community Summit held at the University of Pisa, Pisa, Italy from September 05 to 07, 2018.

Modeling mobility is a key aspect when simulating different types of networks. To cater to this requirement, a large number of models has emerged in the last years. They are typically (a) trace-based, where GPS recordings are re-run in simulation, (b) synthetic models, which describe mobility with formal methods, or (c) hybrid models, which are syn...

One of the major consequences of disasters is the destroyed infrastructure, such as power supply, communication, or roads, which makes it difficult to help affected people. Efficient help requires communication facilities to organize the disaster response but although rebuilding the infrastructure is one of the first priorities, it takes several da...

Simulation is one of the most powerful tools we have for evaluating the performance of Opportunistic Networks. In this survey, we focus on available tools and models, compare their performance and precision and experimentally show the scalability of different simulators. We also perform a gap analysis of state-of-the-art Opportunistic Network simul...

The use of opportunistic communications to disseminate common interest messages in an urban scenario have various applications, like sharing traffic status, advertising shop offers, spread alarms, and so on. In this paper, we evaluate the combined use of fixed and mobile nodes to establish an optimal urban opportunistic network aimed at the distrib...

Nowadays, virtually everybody uses Smartphones or-generally speaking-smart devices. Apps running on these devices are optimized to low energy consumption and good user experience. This poster describes a resource managing approach which optimizes the device usage according to individual users in a way that background services like opportunistic com...

These are the Proceedings of the 4th OMNeT++ Community Summit, which was held at the University of Bremen - Germany - on September 7-8, 2017.

In this paper we present a set of simulation models to more realistically mimic the behaviour of users reading messages. We propose a User Behaviour Model, where a simulated user reacts to a message by a flexible set of possible reactions (e.g. ignore, read, like, save, etc.) and a mobility-based reaction (visit a place, run away from danger, etc.)...

The number of computing devices of the Internet of Things (IoT) is expected to grow by billions. New networking architectures are being considered to handle communications in the IoT. One of these architectures is Opportunistic Networking (OppNets). To evaluate the performance of OppNets, an OMNeT++ based modular simulator is built with models that...

Radio irregularity is a non-negligible phenomenon that has an impact on protocol performances. For instance, irregularity in radio range leads to asymmetric links that cause the loss of packets in different directions. In order to investigate its effect, the Radio Irregularity Model (RIM) is proposed that takes into account the irregularity of a ra...

Radio irregularity is a non-negligible phenomenon that has an impact on protocol performances. For instance, irregularity in radio range leads to asymmetric links that cause the loss of packets in different directions. In order to investigate its effect, the Radio Irregularity Model (RIM) is proposed that takes into account the irregularity of a ra...

Use of mobility models to model user movement in mobile networks is a key aspect when developing and evaluating networking protocols in simulators. A trace obtained from an actual user movement is considered as being more realistic than using synthetic mobility models in simulators. Though realistic, usually, these traces lack information about the...

A poster for OMNeT++ Community Summit 2017.

The Internet of Things (IoT) is expected to grow into billions of devices in the near future. Evaluating mechanisms such as networking architectures for communications in the IoT require the use of simulators due to the scale of the size of networks. Mobility is one of the key aspects that need to be evaluated when considering the different scenari...

Teaching the Internet of Things has become vital in engineering, but also very challenging. This is mainly due to the almost unbelievable variety of available systems, hardware and software components, and online resources. This column discusses how we, at the University of Bremen, approached this problem: with hands-on experience and concept abstr...

The number of computing devices of the IoT are expected to grow exponentially. To address the communication needs of the IoT, research is being done to develop new networking architectures and to extend existing architectures. An area that lacks attention in these efforts is the emphasis on utilisation of omnipresent local data. There are a number...

We are in the process of developing a system architecture for opportunistic and information centric communications. This architecture (called Keetchi), meant for the Internet of Things (IoT) is focussed on enabling applications to perform distributed and decentralised communications among smart devices. To realise and evaluate this architecture, we...

Content Centric Networking (CCN), a "Clean Slate" architecture to Information Centric Networking (ICN) , uses new approaches to routing named content, achieving scalability, security and performance. This thesis proposes a design of an effective multi-path forwarding strategy and performs an evaluation of this strategy in a set of scenarios that co...

There are disclosed measures of address assignment for a network element being operable in a multi-level network, comprising retrieving a network prefix of said multi-level network and network prefix information including at least one of a top-level indication, a suffix length parameter and a maximum prefix length parameter, generating a first addr...

Content Centric Networking (CCN) is a new paradigm in networking and a future Internet architecture. Performance evaluations show that conventional CCN forwarding strategies which use replication of Interests (standard) or the shortest path (best-face) do not perform well under high bandwidth requirements and loaded networks. We have designed and e...

Using Mobile Ad Hoc Networks as a way to break the dependency of mobile communications on permanent infrastructure has been an active area of research for several years, but only more recently has consideration been given to the economics of a distributed mobile service. In particular, the topic of handling nodes that act selfishly or maliciously h...

Content Centric Networking (CCN) is a paradigm shift from the way how networks of today work. The focus of networking in CCN is on the content and not on the hosts that are involved in a communication. One of the key cornerstones of today’s communication model is the use of flow and congestion control to pipeline data and take appropriate action wh...

Content Centric Networking (CCN) is an evolving paradigm in networking where communications are based on named content rather than the named hosts model of today's networks. Though CCN is capable of multi-path communications by design, no work has been done to characterise multi-path content transfers in CCN with an analytical model. In this work,...

In this paper we present an Open Connectivity Services architecture, which has been conceived such as to cope with the challenges posed by the Future Internet. By relying on currently working solutions and establishing a trustworthy migration strategy, the proposed architecture provides a flexible framework that supports both legacy and enhanced co...

One of the primary activities of today’s networks is the movement of content. This has made the point-to-point communication architecture of current networks unsuitable for today’s needs. Information Centric Networking (ICN) changes this model with newer networking architectures such as the Network of Information (NetInf). The multi-path capabiliti...

This chapter explores the question of how to implement opportunistic networks in practice. The main part of this question considers the connectivity technologies that support opportunistic communications. These can be organized into two types: general communication technologies and protocols and concrete software implementations and frameworks. Thi...

In this last technical chapter, we finally present concrete application scenarios for opportunistic networks. We have waited with this discussion until the end so that the properties, advantages, and limitations of opportunistic networks become clear in detail first. Even if many different application cases have been proposed in the literature, not...

When implementing opportunistic networks in real applications, not only connectivity problems need to be addressed, but also device restrictions. Each device (smartphones, sensor nodes, tablets) have its unique properties and resources. Some of them are critical for opportunistic communications and can make the difference between a well-functioning...

In this chapter, we detail how to use theoretical modeling in opportunistic networks (OppNets) using mathematical and computational methods to analyze their behavior. The models, though simplified representations of reality, help researchers predict network performance under different conditions and gain insights into network behavior. Particularly...

In this chapter, we address the evaluation of opportunistic networks in a general way. We introduce the three main approaches: real-world implementations, simulation, and analytical models. We compare them with each other from the perspective of their properties, such as their development and execution costs, repeatability and reproducibility, visi...

In this chapter, we introduce the different simulation models available and needed to simulate opportunistic networks in all their details. They include application (traffic) models, link abstraction models, mobility models, and contact traces. We discuss each of them individually, which concrete models exist, and how they work in general. Furtherm...

In this chapter, we start with an introduction to network simulators and especially to discrete event simulators. We explain how they work and what their most important properties are. We continue with several concrete simulators which can be used for evaluating opportunistic networks: OMNeT++, ONE, and ns-3. We discuss their pros and cons and comp...

This presented work gives an overview on the FP7 project — SAIL, that aims at designing architectures for the Future Networks. The conceptual developments in the work package - Open Connectivity Services (OConS) is the focus of this paper. OConS is proposing an open and flexible architecture framework for handling the connectivities in current and...

Seamless performance of communication applications is critical for today's mobile workers who are dependent on their mobile computing devices. One area of such criticality is the smoothness of handovers between Access Points (APs) in 802.11 based communications. In this work, two heuristic handover algorithms based on indoor positioning are designe...

Network virtualization is a concept where physical resources are used to create virtual resources that are combined to form virtual networks. As one of the key enablers of the future Internet, network virtualization solves a number of issues associated with today’s networks. Concepts of network virtualization that are not restricted to virtualizati...

The Proxy Mobile IPv6 (PMIPv6) is a network based mobility management protocol standard that was ratified recently by the Network-based Localized Mobility Management (NetLMM) working group of the Internet Engineering Task Force (IETF). PMIPv6 is a protocol that uses the same concepts as used in Mobile IPv6 (MIPv6), but modified to operate in the ne...

Internet capable mobile or portable devices are already a modern commodity while it is becoming more and more common that such devices are hosts to more than one wireless network interface. The aim of this work is to show from a user's perspective how such a portable device may make best use of this property by using multiple wireless and wired net...

Today, there exists a large variety of wireless networking technologies. However, the question is how to use all these technologies and the available services together to obtain the best possible advantage for the user and network operators. Currently research is going on over handover techniques that allow the user to seamlessly handover from one...

Next generation networks will consist of heterogeneous access networks and will provide a variety of services. In such an environment the question of the assignment of terminals to access networks and mobility management becomes a challenging problem. This is especially true when one takes the user goals and network operator goals into account. Use...

An evolving wireless world is constantly providing users with a wider set of access technologies to choose from, each with different capabilities and properties. In this world, IMS as defined by 3GPP provides an enabling, standardized multimedia architecture that is access independent, hence, providing service convergence. This trend is accompanied...

Socket to me with the RTNETLINK kernel interface.

The Ad hoc On-Demand Distance Vector (AODV) routing protocol is designed for use in mobile ad-hoc networks. As of the writing of this article, there exist several implementations of the AODV protocol for a range of operating systems (e.g., Unix/Linux, Windows), different devices (e.g. Notebook computers, PDAs) each developed using different techniq...

Mobile IP is the dominant Internet standard for the provision of Internet mobility support. However, Mobile IP does not provide any considerations for simultaneous use of multiple points of attachment. This feature is considered very important for Internet real-time communications. Filters for Mobile IP Bindings is a protocol extension of Mobile IP...

A key area of consideration in self organizing ad hoc networks is the routing mechanisms. The On-Demand mechanism in IP based networks has become popular due to the lower overheads required in managing routes which make it ideal for even smaller, resource restrained mobile computing devices. This publication looks at the implementation aspects of d...