  In the recent years, WiFi standard has been used to develop different kind of
wireless networks due to its flexibility and the availability of cheap off the
shelf hardware. Even if the standard itself lacks mobility support, it has been
used in networks with mobile nodes. When mobility is involved, a fast handoff
is of paramount importance, especially with multimedia applications. The
current IEEE 802.11 standard does not provide any specification about how the
handoff should take place. In this paper we propose a handoff scheme optimized
for networks providing wireless connection to mass transit vehicles. The
structure of the procedure is redesigned to minimize delay as well as assure
reliability. A reliable handoff triggering mechanism is also designed
exploiting the results obtained from a set of preliminary outdoor experiments.
The proposed scheme was implemented and deployed in an experimental testbed,
and several indoor tests were run in order to demonstrate its reliability and
efficiency.
