The LEM Project


The recent advances in wireless client devices, that host heterogeneous wireless technologies spanning from IEEE 802.11 (WiFi) and Bluetooth (BT) to cellular 3G and beyond, and the crucial role of multimedia communications in our society are motivating new multimedia provisioning scenarios in which multimedia content delivery is tailored depending on client location, with different goals, from personalized location-dependent advertising/marketing to enhanced forms of touristic assistance.


The purpose of the called Localized rElay-based mobile Multimedia (LEM) middleware is to provide effective support for seamless multimedia flow delivery in highly populated regions where specific contents should be distributed to geographically bounded Areas of Interest (AOIs), such as personalized and different promotional videos toward the areas used by different exhibitors in an exhibition pavilion.

LEM logo big


LEM significantly differs from state-of-the-art work by combining the following original technical aspects:

  • LEM does not require any pre-installed localization infrastructure. It automatically and continuously re-organizes dense AOI network topology and can exploit any available wireless connectivity opportunity to download and seamlessly re-distribute multimedia content locally.
  • LEM adopts fully decentralized and anchor-free prediction/awareness techniques. It employs effective techniques that permit to precisely demarcate small AOI and effectively exploits mobile relays, automatically re-elected within the community of dense AOI nodes, as both markers for AOI identification and communication gateways for other nodes in the same neighborhood.
  • LEM grants seamless multimedia flow delivery. It estimates that the relay is likely to abandon its AOI center, it proactively triggers relay re-election, and automatically manages the multimedia flow handoff process from the old to the new relay (relay handoff management) to minimize data losses and delays.

LEM is the first proposal in the field for completely decentralized content delivery in dense AOI. LEM is a real and ready-to-deploy content distribution solution: we both validated the proposed support infrastructure in extensive ns-2 simulations and implemented it as an open-source middleware.