No abstract

Hybrid networks are a promising architecture that builds ad hoc, wireless networks around the existing cellular telephony infrastructure. 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 t o optimal spanning tree of the network by using distributed topology trees. DST is fully dynamic and generates only O(1ogn) 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. ' A ~naxirnu~n spanning tree pro\.idrs the optimal ~ro~~ting T o r the next flo~v from a host to the base station.

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.