DS0707 -

Geocasting for Hyper resolution spatial data focusing – GEOHYPE

Submission summary

Associating wireless information to certain physical locations is an interesting feature that many applications can benefit from. This capability is known as geocasting. Just like pictures are tagged with the location where they have been clicked, geocasting enables to tag a real physical location by wirelessly transmitting data that are only decodable within desired delimited areas. Thus, users can receive information related to the place where they are. This is what is achieved to some extent by applications like Google map where metadata related to user’s location are sent. To do so, GPS coordinates of users are required. These systems are limited in terms of spatial resolution, especially in indoor environments, and necessitate some time to calculate user’s locations, thereby introducing a delay, which can be a real limitation. Furthermore, as a general matter, all systems that are based upon user’s locations lead to privacy issues. The geocasting scheme proposed in GEOHYPE is fundamentally different. The idea is to transmit data related to locations whether a user is present or not. So instead of considering a user who locates himself with respect to a global reference system and then correlate his position to some databases to discover surrounding locations of interest, the user is able to read the data only when he is located at the right spot. In that case, it is really the location that is tagged, and not the person. This approach therefore respects users’ privacy and does not introduce any delay as the data is always sent to the desired location (it is up to the user to decide whether or not he wants to listen). Furthermore, since GEOHYPE does not require positioning capability, all the classical positioning system infrastructure (e.g. satellites, multiple base stations…) is not required anymore. The only added infrastructure is the capability for base stations to focus data to specific spots. For this scheme to be attractive enough, this feature has to be performed with minimum complexity, cost, and size. To date, no existing techniques are capable of realizing the geocasting scheme without hardware that is too complex, too expensive, too bulky, and too demanding in terms of energy.

Consequently, GEOHYPE’s focus is to investigate physical solutions that enable the broadcasting of information to specific spatial locations, using limited infrastructures. From a scientific point of view, the problem is to find a way for a base station to wirelessly transmit data that are decodable only within desired areas. To do so at the physical layer, base stations have to exhibit spatial focusing capabilities. Multiple-Input Single-Output (MISO) architectures can be used for that purpose and beamforming techniques applied so that base stations can radiate signals toward particular directions only. In that case, the geocasting feature is achieved through power focusing. The approach undertaken by GEOHYPE is radically different. The goal is to focus the transmitted data rather than focusing the transmitted power. The idea is to process the data in order to be decodable only at a predetermined spot. This scheme can overcome the classical limitations of beamforming techniques where the antenna arrays have to be large in order to focus the radiated power within a limited-size area. GEOHYPE will show that focusing only the data is spatially more selective than focusing power. The required MISO systems will be therefore much lighter as only a limited number of transmitting antennas will be necessary in order to achieve enhanced angular selectivity. This project involves electromagnetic wave propagation, wireless communications, and signal processing.

Project coordination

Julien Sarrazin (Laboratoire d'Electronique et Electromagnétisme)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


ULB Université Libre de Bruxelles
L2E Laboratoire d'Electronique et Electromagnétisme

Help of the ANR 225,160 euros
Beginning and duration of the scientific project: November 2016 - 48 Months

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