The Directorate of Technical and Quality Management has recently taken a new initiative, the ESA's Networking / Partnering Initiative (NPI), to support research work carried out by universities and research institutes on advanced technologies with potential space applications. The objective is to foster the interactions between ESA, European universities, research institutes and industry. This initiative is implemented through the financing or co-financing of PhD or Post-Doctoral research work in universities, laboratories or institutes. The CTTC has recently been granted a co-funded fellowship to support the PhD studies of Giuseppe Cocco, PhD student of the CTTC, supervised by Dr. Christian Ibars, research coordinator of the Access Technologies area of the center.
The research work will focus on the topic of cooperative communications. Interactive satellite broadcast services to mobiles are a large potential market with new applications for multiple scenarios, as it is the case, for example, for the vehicular scenario and the emergency distribution. In order to efficiently implement these interactive services several technical issues have to be addressed. As a matter of fact, in satellite communications only users with good enough channel conditions are able to access to interactive services. Indoor users, or users to which the satellite is "hidden" by high buildings, may not be able to access the offered services. In these cases terrestrial gap fillers are employed to provide the missing coverage. However, this technology provides quite a rigid solution, besides being an expensive choice in terms of investment, management, and bandwidth usage.
The purpose of this partnership activity with the ESA is to propose a more flexible solution based on an ad-hoc networking approach (i.e. without fixed infrastructure, as it is the case for a cellular system), where each user is capable of communicating directly with the satellite, as well as with other nodes. In such a scenario, some of the users with the best communication conditions from the satellite can act as mobile gap-fillers, helping to improve the service coverage.
In order to achieve this result, a set of new techniques, named cooperative communications, has to be studied and applied to the context of satellite communications. As suggested by the name, the concept of cooperative communications consists of a mutual collaboration among nodes - collaboration that will bring significant advantages to all the agents, thus enhancing the overall system performance.
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