The specific study objectives are many, but they can all be summarized by asking the following simple question: “Is there a business case for MSS in the fourth generation of mobile networks?”
The question is far from being naïve. As a matter of fact, the twist that history has taken at the turn of the new millennium appears to indicate that if bold actions are not taken, and taken fast, the answer will be that there will only be a very marginal role, if any, for MSS in 4G. There is an apparent offset in the speed of evolution of terrestrial networks with respect to MSS networks, and 4G may be the last chance to jump on this fast running train.
The study therefore encompasses all of the elements which can be used to decide about the viability and the role of satellites in 4G. It tackles market and service aspects, regulatory and standardization issues, technical challenges and solutions, and business issues.
- Identification of the most interesting business opportunities in the 4G mobile market that exploit a satellite element.
- Design of a system architecture with satisfactory coverage and capacity characteristics.
- Evaluation of the feasibility of using a 4G air interface through a satellite. Specifically, WiMAX and 3GPP LTE air interfaces must be evaluated.
- Definition of terminal architecture and analysis of cost, power, form factor, in view of mass market production.
- Evaluation of higher layer protocols and protection mechanisms.
Since the partnership of this project includes a major satellite manufacturer and a major chipset manufacturer for terrestrial mobile terminals, the potential benefits are very significant. Indeed, it is a rare event when major actors from these two separate worlds sit together and cooperate for a feasibility study. The impact could be on standardization bodies (ETSI, 3GPP) and on future technical and business developments.
From the initial market analysis two system scenarios have been selected: mobile broadcasting for the consumer market and two-way communications for the professional market. The space segment study led to the selection of a constellation of one or two GEO satellites. On ground, a complementary component of gap-fillers is foreseen, with various possible levels of interaction with the 4G terrestrial mobile network. See the diagram below for a schematic view of the system architecture.
The Project was successfully completed in December 2008, and the final presentation of project activities was held at the ESA/ESTEC premises on December 16, 2008.
The Project kicked off on November 15, 2006.
Phase 1 activities, envisaging the definition of the preliminary system architecture and considering market/business issues, were successfully completed after the CDR meeting held on October 24, 2007 at ESA/ESTEC premises in Noordwijk.
Phase 2 activities, devoted to the detailed analysis of the most critical technical issues identified in Phase 1, were kicked off right away. In particular, PM4 was held on July 15-16, 2008, where the performance results of advanced physical and access layer techniques were presented.
The project was successfully completed at the end of 2008. All the deliverables have been finalized, including the overall system performance, the future roadmap and the updated business analysis. The system architecture was defined based on a detailed market analysis. An extensive simulation campaign has been performed to analyse the physical layer performance of 3GPP LTE and WiMAX air interfaces through a satellite channel.
The space segment has been defined, with several options for S-band, C-band single and multiple missions. A system level performance assessment methodology has been determined to evaluate the overall performance figures. The terminal architecture has been taken into consideration, aiming at introducing marginal cost increments with respect to standard 4G mobile terminals. Optimized scheduling algorithms have been considered in several scenarios.