Teemu Kärkkäinen

The ONE simulator for DTN protocol evaluation

Delay-tolerant Networking (DTN) enables communication in sparse mobile ad-hoc networks and other challenged environments where traditional networking fails and new routing and application protocols are required. Past experience with DTN routing and application protocols has shown that their performance is highly dependent on the underlying mobility and node characteristics. Evaluating DTN protocols across many scenarios requires suitable simulation tools. This paper presents the Opportunistic Networking Environment (ONE) simulator specifically designed for evaluating DTN routing and application protocols. It allows users to create scenarios based upon different synthetic movement models and real-world traces and offers a framework for implementing routing and application protocols (already including six well-known routing protocols). Interactive visualization and post-processing tools support evaluating experiments and an emulation mode allows the ONE simulator to become part of a real-world DTN testbed. We show sample simulations to demonstrate the simulators flexible support for DTN protocol evaluation.

Simulating Mobility and DTNs with the ONE (Invited Paper)

Delay-tolerant Networking (DTN) enables communication in sparse mobile ad-hoc networks and other challenged environments where traditional networking fails and new routing and application protocols are required. Past experience with DTN routing and application protocols has shown that their performance is highly dependent on the underlying mobility and node characteristics. Evaluating DTN protocols across many scenarios requires suitable simulation tools. This paper presents the Opportunistic Networking Environment (ONE) simulator specifically designed for evaluating DTN routing and application protocols. It allows users to create scenarios based upon different synthetic movement models and real-world traces and offers a framework for implementing routing and application protocols (already including six well-known routing protocols). Interactive visualization and post-processing tools support evaluating experiments and an emulation mode allows the ONE simulator to become part of a real-world DTN testbed. We examine a range of published simulation studies which demonstrate the simulator’s flexible support for DTN protocol evaluation.

Searching for content in mobile DTNs

Delay-tolerant Networking (DTN) provides a platform for applications in environments where end-to-end paths may be highly unreliable or do not exist at all. In many applications such as distributed wikis or photo sharing, users need to be able to find content even when they do not know an unambiguous identifier. In order do bring these applications to the domain of DTNs, a search scheme is required that works despite the unreliable network conditions. In this paper, we introduce a search scheme that makes no assumptions about the underlying routing protocols and the format of search requests. We evaluate different algorithms for forwarding and terminating search queries, using simulations with different classes of DTN routing protocols for different mobility scenarios.

SCAMPI: service platform for social aware mobile and pervasive computing

Allowing mobile users to find and access resources available in the surrounding environment opportunistically via their smart devices could enable them to create and use a rich set of services. Such services can go well beyond what is possible for a mobile phone acting alone. In essense, access to diverse resources such as raw computational power, social networking relationships, or sensor readings across a set of different devices calls for distributed task execution. In this paper, we discuss the SCAMPI architecture designed to support distributed task execution in opportunistic pervasive networks. The key elements of the architecture include leveraging human social behavior for efficient opportunistic interaction between a variety of sensors, personal communication devices and resources embedded in the local environment. The SCAMPI architecture abstracts resources as service components following a service-oriented model. This enables composing rich applications that utilize a collection of service components available in the environment.

Opportunistic web access via WLAN hotspots

Mobile phones are becoming commonplace for consuming Internet content and services. However, availability, affordability, and quality of the supposedly ubiquitous cellular network infrastructure may be limited, so that delay-tolerant web access via WLAN hotspots becomes an interesting alternative, even in urban areas. In this paper we explore mobile web access using asynchronous messaging via WLAN hotspots: for nodes directly connected to an access point and nodes relying on others for message forwarding. We investigate different routing and caching approaches using real-world access point locations in Helsinki. We find that a significant number of requests can be satisfied without requiring an always-on infrastructure, provided that users are willing to tolerate some response delay; this allows offloading traffic from the cellular network. We also report on our prototype implementation of mobile DTN-based web browsing.

Opportunistic email distribution and access in challenged heterogeneous environments

The communication paradigms for delay-tolerant networking have been modeled after email. Supporting email over DTNs in a backwards compatible manner in a heterogeneous environment has yet to be fully defined. In this paper, we present a set of conventions for and extensions to the DTNRG architecture. We have implemented a system that is able to deliver emails within a DTN network, from a DTN network to the Internet, and from the Internet to the DTN network. Our system architecture includes multiple solutions for integrating traditional and DTN-based mail delivery: DTN-based messaging clients for mobile phones and PDAs, a dedicated, stand-alone DTN gateway between the Internet and the DTN network, and a personal DTN mail application proxy. The latter bridges to unmodified mail user agents running on a laptop.

Mobility and service discovery in opportunistic networks

Past research on opportunistic communications has demonstrated the power of mobile phones as information mediators and content providers to co-located devices. As an extension of opportunistic communication paradigm, opportunistic computing and services research leverages the powerful capabilities and pervasive nature of modern smartphones to provision services to nearby nodes. When an opportunistic network is viewed as a provider of services rather than as a simple message routing system, node and service discovery come to play a critical role. This paper discusses several factors that affect the discover ability of pervasive services with current existing devices in light of their practical limitations. Moreover, the impact of these limitations to pervasive service discovery is studied in evaluation results.

SCAMPI application platform

In this paper we demonstrate an application platform architecture and implementation that allows developers to easily target opportunistic networks. The platform includes an opportunistic router, HTML5 application development framework, and an opportunistic application market for distributing applications. We demonstrate the platform and multiple HTML5 applications -- including chat, music and social networking applications -- running on Android devices.

Liberouter: Towards autonomous neighborhood networking

We present the Liberouter framework, a complete communication system design (and its implementation) to enable neighborhood networking without relying on the Internet infrastructure for information exchange. The core is a low-cost router platform that serves as WLAN access points, individual or (dis)connected ones, and offers message storage and relaying in combination with a distributed app store. It allows bootstrapping Android devices to become additional routers (and thus expand the network) and install applications. It also instruments other mobile devices to assist in message forwarding and offers web-based access to content of the neighborhood stored locally.

Shared content editing in opportunistic networks

This paper examines shared content editing in opportunistic networks. Instead of immutable messages, such as photos or music files that are often assumed in opportunistic network applications, we focus on mutable content, such as wiki-pages, that can be edited by anyone carrying a copy. We show through simulations that mutable content can be handled by using revision control mechanisms (merging), or by simply adopting/discarding versions wholesale.