Communications Challenges in the Celtic-BOSS Project G´aborJeney 1 , Catherine Lamy-Bergot 2 , Xavier Desurmont 3 , Rafael Lopez da Silva 4 , Rodrigo ´ Alvarez Garc´ ıa-Sanchidri´an 5 , Michel Bonte 6 , Marion Berbineau 7 , M´arton Csapodi 8 , Olivier Cantineau 9 , Naceur Malouch 10 , David Sanz 11 , and Jean-Luc Bruyelle 12 1 Budapest University of Technology and Economics, Hungary, jeneyg@hit.bme.hu 2 THALES Communications, France Catherine.LAMY@fr.thalesgroup.com 3 Multitel Asbl, Belgium desurmont@multitel.be 4 Telef´onica Investigacion y Desarollo, Spain ralds@tid.es 5 Ingenier´ ıa y Econom´ ıa del Transporte, S.A., Spain rodrigo.alvarez@ineco.es 6 ALSTOM-TRANSPORT, France michel.bonte@transport.alstom.com 7 Institut National de Recherche sur les Transports et leur S´ ecurit´ e, France marion.berbineau@inrets.fr 8 EGROUP-Services Ltd, Hungary marton.csapodi@egroup.hu 9 BARCO-SILEX, Belgium olivier.cantineau@barco.com 10 University Pierre and Marie Curie, France Naceur.Malouch@lip6.fr 11 Soci´ et´ e Nationale des Chemins de fer Fran¸cais, France david.sanz@sncf.fr 12 Universit´ e Catholique de Leuven bruyelle@tele.ucl.ac.be Abstract. The BOSS project [1] aims at developing an innovative and bandwidth efficient communication system to transmit large data rate communications between public transport vehicles and the wayside to answer to the increasing need from Public Transport operators for new and/or enhanced on-board functionality and services, such as passen- ger security and exploitation such as remote diagnostic or predictive maintenance. As a matter of fact, security issues, traditionally covered in stations by means of video-surveillance are clearly lacking on-board trains, due to the absence of efficient transmission means from the train to a supervising control centre. Similarly, diagnostic or maintenance is- sues are generally handled when the train arrives in stations or during maintenance stops, which prevents proactive actions to be carried out. The aim of the project is to circumvent these limitations and offer a system level solution. This article focuses on the communication system challenges.