By analyzing the interaction between high node mobility, road topology and radio characteristics of this network we identify the two major challenges of information dissemination in VANETs: i) limited connectivity and ii) limited bandwidth. We tackle the first challenge by positioning additional infrastructure-based supporting units. In oder to approach the second challenge, we propose different aggregation mechanisms. These aim to minimize the amount of data transmitted in the network. It allows thus to inform all vehicles in the network in due time about current road situations. This book addresses readers interested in mobile ad hoc networks, in particular researchers and developers working on vehicular networks. In this book, we analyze information dissemination in the context of vehicle-to-vehicle communication in vehicular ad hoc networks (VANETs). In order to inform cars about current traffic situations in a city scenario, information needs to be spread in the whole network.
Avoiding the Gridlock. Information Dissemination in Vehicular Networks
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Evaluating the GPRS Radio Interface for Different Quality of Service...
Figure 8 i ves iga es he impac of he maximum umber of GPRS user per cell o he performa ce of GPRS for he dy amic cha el alloca io scheme wi h 1 PDCH reserved. Of course, he expec ed umber of GPRS users should be less ha he maximum umber i order o avoid he rejec io of ew GPRS sessio s. O he o her ha d, he maximum umber of ac ive GPRS sessio s mus be limi ed for guara eei g quali y of service for every ac ive GPRS sessio eve u der high raffic. he radeoff be wee i creasi g performa ce for allowi g more ac ive GPRS sessio s a d he i creasi g blocki g probabili y for GPRS users is illus ra ed by he curves of Figure 8. Co clusio s his paper prese ed a discre e-eve simula or o he IP level for he Ge eral Packe Radio Service (GPRS). Wi h he simula or, we provided a comprehe sive performa ce s udy of he radio resource shari g by circui swi ched GSM co ec io s a d packe swi ched GPRS sessio s u der a s a ic a d a dy amic cha el alloca io scheme. I he dy amic scheme we assumed a reserved umber of physical cha els perma e ly alloca ed o GPRS a d he remai i g cha els o be o -dema d cha els ha ca be used by GSM voice service a d GPRS packe s.