The scenario of GNSS is speeding up on a no-return track towards a multi-constellation and multi-frequency GNSS world. On top of the good-ole-boy GPS, the re-born GLONASS system is steadily improving. The exciting perspectives of new global systems as Galileo or Compass are getting closer to reality. Regional systems as QZSS or IRNSS are also on the starting line. Augmentation systems flourish worldwide: WAAS, EGNOS, MSAS, GAGAN ... Within this seemingly chaotic scenario of possibilities, some initiatives are actively working on the definition of efficient, pragmatic and user-oriented approaches to take advantage of this new challenging scenario into a maximum-benefit scheme for all GNSS users. In particular Europe has launched, under ESA's European GNSS Evolution Programme, the MRS initiative. MRS standing for Multi-constellation/multi-frequency Regional System, the initiative is putting different teams of experts into the exciting goal of defining the paths for the most successful GNSS usage on a future of multiple choices. Following this approach and based on the promising study results obtained so far by ESA (see ref [1]) MRS is increasingly becoming a serious and natural candidate for the evolution of the current EGNOS System which is qualified and in operations since 3 years and which delivers both an Open Service and a Safety Of Life aeronautical service (same as WAAS). EGNOS is on the way to certification planned for mid 2010. But MRS is not just looking far in the wonderful future of several matured GNSS systems. Also the present and short term future are being taken into account, based on what we have today and aiming to improve the services that we are already providing to ourselves today, as GNSS users. Today we do have already a multi-constellation scenario, with GLONASS getting close to having the nominal constellation in operation. Furthermore, processing platforms as that of EGNOS, magicSBAS or SPEED [2] already implement the ability of processing GLONASS data into an SBAS solution. Based on these available tools, ESA has prepared a detailed experimentation plan aimed to demonstrate the benefits that the multi-constellation approach can provide to today's GNSS users. This plan covers a wide range of objectives covering different user domains (aeronautical, land mobile, maritime) equipped with different types of receivers. This set of experimentations will rely on the deployment of several Test Beds combining multi constellation multi-frequency processing and multi broadcast channels (GEO, MEO, terrestrial). Among the first experimentations planned, there are some devoted to experiment and validate the performance benefits for SBAS users (GPS L1 only first then GPS/GLONASS or GPS/Galileo - L1/E1 mono frequency or dual frequency E1/E5 SBAS users). This paper presents the outcome of the first step of this experimentation campaign, which has been performed based on the magicSBAS tool, a flexible SBAS processing platform, able to acquire single and dual frequency GLONASS data, in addition to GPS, in order to compute and provide both standards SBAS corrections and integrity, as well as augmentation to GLONASS. The objectives of this first step are twofold: 1. Analyse the benefits for single frequency users of using both GPS and GLONASS augmentation, in particular for uncontrolled environments, where the visibility of additional satellites play a key role on the reliability of the GNSS services, as for instance for urban applications. 2. Analyse the potential benefits that can be achieved by improving the standards GPS L1 SBAS augmentation service, when GLONASS data are used within the processing facility to improve the overall accuracy, integrity and continuity of the service. In particular we will analyse how such a dual-frequency/dual constellation processing can improve ionospheric information, by increasing: - accuracy, with more visible satellites - robustness, for instance against scintillation effects - service coverage, by offering improved (more accurate and more available) Ionospheric Grid Point monitoring to users located at the service area boarder; - reliability with better geometry for integrity monitorisation The results of the analysis will be used as a key proof of concept for the definition of the short term evolutions of current European GNSS initiatives, which goes beyond the usage of GLONASS towards the incorporation of Galileo in a truly System of Systems, where all users, including legacy users will be able to exploit the advantages stemming from optimized performances, higher reliability, maximum integrity and seamless navigation. MRS is one of several worldwide initiatives, but it is marching steadily and actively towards its goals, and there is no better way to march than by experimenting, trying and learning from practice.
