Topic overview

My main research activities happen in the domain of Wireless distributed networks, ad hoc and sensor networks. These networks pose interesting challenges to researchers due to their characteristics:

  • They use a wireless medium, usually with a random access procedure on a single channel. Therefore the MAC layer has a primary role in the network performance, as the medium is shared between several nodes.
  • They are spread over a large geographic area. Consequently, the contention os often asymmetric.
  • They are fully distributed, therefore no single central point is able to take decisions and to propagate information in a reasonable amount of time.
  • The nodes are usually considered as mobile, therefore the topology of the network often changes, which either requires a topology-independent sets of protocols, or a frequent neighbors discovery process.
  • They shall comprise a great amount of nodes, thus scalability becomes an issue for end-to-end communication.
  • The nodes are generally mobile and their communication capability is limited by their energy reserve.

On this Figure, circles represent the communication range of different nodes and dashed lines the ability of two nodes to communicate (a "link"). When node A wishes to communicate to node B, the frames have to be relayed by intermediate nodes.

This figure represents a small sensor network. All sensors report to the central sink S. Some sensors (in red) have died disconecting the orange ones, even though these latest are still alive.

I am particularly interested in MAC sub-layer aspects, as it directly conditions the performance one may expect from the network. The MAC sub-layer is, in this context, responsible for finding and enforcing the correct compromise between raw performance, fairness and energy consumption, which are contradictory objectives in several practical situations.

Involved students

  • N'deye Amy Dieng, on opportunistic localization in wireless networks.
  • Maciej Franecki, on publish and subscribe-based middleware in wireless sensor networks.
  • Erwing Sanchez, on MAC protocols adaptations for wireless sensor networks.

Related contractual research projects

  • The ANR project Diaforus.
  • The ANR project Georacing studied the possibility to use ad hoc networking techniques for cyclist races.