Séminaire de Cryptographie

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Jean-Claude Belfiore

Packings on the Grassmann manifold: an interesting approach for non coherent space-time coding

The need of high data rates on the radio channel (WiFi and its future for example) explains the increasing number of researchers working on space-time codes. Preparing Wireless IP systems, some companies and some researchers are promoting the use of non coherent space-time codes.

We show that designing a non coherent space-time code is equivalent to finding some good packings on the Grassmann manifold. But the minimum distance of the packing is not a Euclidean distance and the codes need to be decoded with a "not too complex" algorithm. To solve this problem, we propose a new family of codes on the Grassmann manifold as well as the associated performances.