Abstract—The IEEE 802.21isarecent standardfor enabling handover in heterogeneous wireless networks, which defines protocols and messages for mobile-to-node and node-to¬node communication in a technology-neutral and flexible manner. The need arises because of the widespread diffusion of different technologies for wireless communications (e.g., WiFi,WiMAX,LTE), which are often coexisting in the same geographical area and supported by the same mobile device, but seldom interoperable. In this paper we propose the architecture of a Media Independent Information Service (MIIS) and theproceduresfora network-assisted handover, which are left unspecifiedbythe standard, aimed atreducing the energy consumption of mobile nodes due to scanning.A detailed description of the software modules involved and their interactionsis included.Testbedresultsarereportedto show the effectiveness of the proposed solution with COTS devices.