Hybrid Wireless Networks

  • Shivajit Mohapatra, Bogdan Carbunar, Michael Pearce, Rohit Chaudhri, Venu Vasudevan.
    "Where-Fi: A Dynamic Energy-Efficient Multimedia Distribution Framework for MANETs", In Proceedings of the 15th SPIE/ACM Annual Multimedia Computing and Networking Conference (MMCN), San Jose, January 2008 [26%] [pdf]

    Next generation mobile ad-hoc applications will revolve around users' need for sharing content/presence information with co-located devices. However, keeping such information fresh requires frequent meta-data exchanges, which could result in significant energy overheads. To address this issue, we propose distributed algorithms for energy efficient dissemination of presence and content usage information between nodes in mobile ad-hoc networks. First, we introduce a content dissemination protocol (called CPMP) for effectively distributing frequent small meta-data updates between co-located devices using multicast. We then develop two distributed algorithms that use the CPMP protocol to achieve ``phase locked" wake up cycles for all the participating nodes in the network. The first algorithm is designed for fully-connected networks and then extended in the second to handle hidden terminals. The ``phased locked" schedules are then exploited to adaptively transition the network interface to a deep sleep state for energy savings. We present two novel applications (called ``Zeitgeist" and ``MeCast") developed using our protocol that present compelling ``social experiences" for users. We have implemented a prototype system (called ``Where-Fi") on several Motorola Linux-based cell phone models. Our experimental results show that for all network topologies our algorithms were able to achieve ``phase locking" between nodes even in the presence of hidden terminals. Moreover, we achieved battery lifetime extensions of as much as 28% for fully-connected networks and about 20% for partially-connected networks.

  • Bogdan Carbunar, Brett Lindsley, Michael Pearce, Venu Vasudevan.
    "Verifiable Credit Based Transfers in Wireless Ad Hoc Networks". In Proceedings of the 21st IEEE International Parallel and Distributed Processing Symposium (IPDPS), Long Beach, March 2007 [26%] [pdf]

    Encouraging cooperation between users of mobile devices operating in ad Hon mode is a difficult task mostly because the scarce battery and bandwidth resources of devices suggest that selfish behavior may be most beneficial. The insecure usage of credits to reward cooperation can easily provide an incentive for cheating, thus, on the long term only leading to selfishness. In this paper we propose several secure credit based mechanisms enforcing fairness in a hybrid wireless content retrieval system operating both in cellular and ad Hoc connectivity modes. Our solution consists of mechanisms for securely and privately discovering desired content on neighboring devices, simultaneously exchanging credit and content shares in a verifiable manner and for generating and expiring non-forgeable credits. We present experimental results of a partial prototype of our system implemented on MPx and E680i cellular phones and HP iPaq hx4700 PDAs, along with extensive simulation results showing that our solution significantly reduces the effectiveness of selfish behavior, making it an unattractive strategy.

  • Ioannis Ioannidis, Bogdan Carbunar, Cristina Nita-Rotaru.
    "High Throughput Routing in Hybrid Cellular and Ad-Hoc Networks". In Proceedings of the 6th IEEE Symposium on World of Wireless, Mobile and Multimedia (WOWMOM), Taormina, July 2005 [pdf]

    In this paper we present DST, a routing protocol for hybrid networks that is scalable with the network size and achieves high throughput by taking advantage of multiple channels. DST maintains a close to optimal spanning tree of the network by using distributed topology trees. DST is fully dynamic and generates only O(log n) messages per update operation. We show experimentally that DST scales well with the network size, making it ideal for the metropolitan environment hybrid networks are expected to operate in.

  • Bogdan Carbunar, Ioannis Ioannidis, Cristina Nita-Rotaru.
    "JANUS: Towards Secure and Malicious Resilient Routing in Hybrid Cellular and Ad Hoc Networks". In Proceedings of the 3rd Workshop on Wireless Security (Wise), held in conjunction with Mobicom, Philadelphia, October 2004 [25%] [pdf]

    In this paper we investigate and provide solutions for security threats in the context of hybrid networks consisting of a cellular base station and mobile devices equipped with dual cellular and ad-hoc (802.11b) cards. The cellular connection is used for receiving services (i.e. Internet access) from the base station, while the ad-hoc links are used to improve the quality of the connection. We provide detailed descriptions of several attacks that arbitrarily powerful adversaries, whether outsiders or insiders, can mount against wellbehaved members of the network. We introduce a secure routing protocol called JANUS, that focuses on the establishment of secure routes between the base station and mobile devices, and the secure routing of the data. We show that our protocol is secure against the attacks described and experimentally compare the message overhead introduced by JANUS and UCAN.

  • Ioannis Ioannidis, Bogdan Carbunar.
    "Scalable Routing in Hybrid Ad Hoc and Cellular Networks" (extended abstract/poster). Accepted for publication in the 1st IEEE International Conference on Mobile Ad Hoc and Sensor Systems (MASS), Fort Lauderdale, October 2004

  • Bogdan Carbunar, Ioannis Ioannidis, Ananth Grama, Jan Vitek.
    "A Secure Crediting Protocol for Hybrid Cellular and Ad Hoc Networks". In Proceedings of the 1st International Conference on E-Business and Telecommunication Networks (ICETE), Setubal, August 2004 [pdf]