A Calculus for Mobile Ad Hoc Networks [chapter]

Jens Chr. Godskesen
Lecture Notes in Computer Science  
We suggest a Calculus for Mobile Ad Hoc Networks, CMAN. A node in a network is a process equipped with a location, it may communicate with other nodes using synchronous spatially oriented broadcast where only the current neighbors receive the message. Nodes may autonomously change their neighbor relationship and thereby change the network topology. We define a natural reduction semantics and strong and weak reduction congruences as well as a labeled transition semantics and prove strong and
more » ... contextual bisimulation respectively to be sound and complete co-inductive characterizations of the corresponding reduction congruences. For the subset of connection closed networks we show a significantly simpler co-inductive characterization. Finally, we apply CMAN on a small example of a cryptographic routing protocol. The use of wireless networks is becoming more and more important due to the increasing and widespread use of communicating mobile devices. The application area for wireless networks is broad, spanning from ambient intelligence, wireless local area networks, sensor networks, and cellular networks for mobile telephony. Our work is devoted to a particular kind of wireless networks, the so called Mobile Ad Hoc Networks (MANETS). MANETS are self organizing wireless networks without centralized access points or any other central control components. Hence they do not contain a pre-deployed infrastructure for routing messages. An ad hoc network may be formed when a collection of mobile nodes join together and agree on how to route messages for each other over possibly multiple hops. The communication primitive for wireless devices is message broadcast. However in contrast to the conventional technology in wired local area networks, say the Ethernet, where broadcasted messages reach every node in the network, then for wireless networks broadcast is spatially oriented meaning that messages will only reach those nodes within the communication range (the cell) of the emitting node. Another difference between wired and wireless network technology is that interference is a much harder and severe problem in wireless systems. Also, in wireless networks communication links between entities cannot always be considered bidirectional. Calculi for broadcast systems were first studied by Prasad in the work on the CBS calculus [16] and later in a mobile setting by Ene and Muntean in the bπ calculus [5], and by Ostrovsky, Prasad, and Taha in HOBS [15] . Recently wireless broadcast systems have been studied by Nanz and Hankin in CBS# [13] and by Merro in CMN [8]. In the former calculi broadcast scope is transitive in that if two nodes P and Q both can communicate with a third node then P and Q can also communicate with each other whereas this is not necessarily the case for CBS# and CMN. The calculus CWS [9] by Mezzetti and Sangiorgi also studies wireless broadcast but at a much lower level of abstraction, in particular they take the phenomenon of interference into account. Another characteristic of MANETS is that nodes may be mobile, not only do they enter and leave the network, but also they autonomously change localities and thereby change their connections and hence the topology of the network. Mobility of processes has been addressed by many calculi, like π [11], Mobile Ambients [3], Seal [4], and Homer [7], and some even take the notion of spatially oriented communication into account like Mobile Ambients and Hennessy and Riely's Dπ [17] . However only very limited work has so far been devoted to calculi for broadcast and mobility, like bπ and HOBS, and to our knowledge the only reported work on calculi for spatially oriented broadcast and mobility is CBS# and CMN. The goal of our work is to define a Calculus for Mobile Ad Hoc Networks (CMAN) that facilitates mobility and spatially oriented broadcast. As in CMN we adopt that communication between nodes in a network is carried out on
doi:10.1007/978-3-540-72794-1_8 dblp:conf/coordination/Godskesen07 fatcat:rmjrmqidffbhtg4fflrc3l5wae