Serval is an open-source, delay-tolerant wireless ad-hoc networking system designed to allow communications anywhere and anytime, despite the total loss of supporting telecommunications infrastructures provided by mobile phone operators. In emergency situations, Serval can be used to establish a disaster-response communications network spontaneously formed by mobile phones and/or battery powered wireless routers. In this paper, we present an in-depth experimental evaluation of Serval for various network setups and usage patterns, including simulated long term use. The focus of our evaluation is on the delay-tolerant aspects of Serval, providing insights into the scenarios where Serval can be deployed with satisfactory quality and performance characteristics. Furthermore, since mobile phones have a limited battery capacity, we take a closer look at the battery drain resulting from using Serval over different communication links, such as WiFi and Bluetooth. Our purpose in providing these analyses is to understand the current capability of Serval and identify any areas where further improvement is required, and to provide a summary of current readiness of Serval in advance of planned pilots in the Pacific region.

Mobile edge computing based on cloudlets is an emerging paradigm to improve service quality by bringing computation and storage facilities closer to end users and reducing operating cost for infrastructure providers (IPs) and service providers (SPs). To maximize their individual benefits, IP and SP have to reach an agreement about placing and executing services on particular cloudlets. We show that a Nash Bargaining Solution (NBS) yields the optimal solution with respect to social cost and fairness if IP and SP have complete information about the parameters of their mutual cost functions. However, IP and SP might not be willing or able to share all information due to business secrets or technical limitations. Therefore, we present a novel iterative bargaining approach without complete mutual information to achieve substantial cost reductions for both IP and SP. Furthermore, we investigate how different degrees of information sharing impact social cost and fairness of the different approaches. Our evaluation based on the mobile augmented reality game Ingress shows that our approach achieves up to about 82% of the cost reduction that the NBS achieves and a cost reduction of up to 147% compared to traditional Take-it-or-Leave-it approaches, despite incomplete information.

Programming paper: Network programmability will be required to handle future increased network traffic and constantly changing application needs. However, t...

Disruption-tolerant networks (DTNs) have a wide range of applications, such as emergencies where traditional communication infrastructure has been destroyed, remote rural deployments where communication infrastructure has never existed, and environmental monitoring where animals are equipped with sensors and transmit data whenever they come into contact with a base station. Using the de-facto DTN protocol standard, i.e., Bundle Protocol version 7 (BPv7), nodes transmit data via so-called Convergence Layer Protocols (CLPs) that act as general abstractions for the underlying communication technologies. BPv7 specifies MTCP and TCPCL as the two current CLPs for DTNs. However, both of them have different but equally undesirable shortcomings in terms of functionality, complexity, performance, and reliability. In this paper, we present QUICL, a novel CLP for DTNs. QUICL is based on the QUIC transport protocol and fully leverages QUIC's advantages over TCP-based transport protocols in a DTN environment. In particular, QUICL provides improved congestion control, allows multiplexing, ensures reliable transmission, effectively manages unreliable links, and uses encryption by default. Our prototypical implementation, already merged upstream, is based on the free and open-source DTN7-go protocol suite and the QUIC-go implementation. Our experimental evaluation shows that even with 30% packet loss, QUICL can still deliver data with minimal CPU overhead in scenarios where most other DTN/CLP combinations fail to transmit any data successfully.