Problem statement

The vast majority of current security techniques are based on cryptographic primitives, which rely on mathematical problems that are conjectured to be hard to solve with finite computational power and limited time. However, no stronger notion of security, based on information theory, is guaranteed. Moreover, security mechanisms have been implemented at all layers of the network architecture, except from the physical one.

In the light of these limitations, the general objective of this project is to provide information-theoretic security at the physical layer based on the interplay, enabled by 5G technologies, between propagation mechanisms and advanced signal processing algorithms.

Geocasting

Associating wireless information to certain physical locations is an interesting feature that many applications can benefit from. This is especially favorable in the context of Internet-of-Things or smart-city environments, where a huge number of connected devices could benefit from this location related or contextualized information concerning traffic, tourism, marketing... Geocasting, i.e. location-based multicasting, offers promising prospects in this domain, by offering spatially confined access to wirelessly transmitted information. For geocasting to be an attractive scheme, its functionality has to be performed with high accuracy, low complexity, and compact size.

Contributions

The project is articulated around different tracks. The two main tracks will make significant progress in two crucial aspects of PLS: optimization of secrecy capacity based on waveform design and secret-key generation based on channel reciprocity. An additional track will extend and generalize the results of the two previous ones to 5G massive MIMO systems, seen as one of the key technology to revolutionize PLS. Finally, a last track connects with all of the other WPs as it involves experimental validation of the different tasks of the project.

Spatial Data Focusing

Spatial Data Focusing (SDF) allows to improve performance in all three of geocasting’s performance criteria, compared to currently used techniques (e.g. beamforming). SDF ‘s channel-based modulation performs a distributed transmission of a datastream over a Multiple-input Single-output channel and exploits at the receiver the different propagation conditions of each data substream to induce an intentional and location-dependent symbol distortion on one or multiple substreams. Low bit-error-rate, i.e. reliable communication is only possible when all data substreams are correctly recovered. By design of the SDF system, this occurs in spatially restricted areas only, hence ensuring geocasting.