METHOD FOR ENERGY-EFFICIENT SCANNING TO ENABLE SEAMLESS LAYER-2 VERTICAL HANDOFFFS BETWEEN WIRELESS BROADBAND NETWORKS
A mechanism that minimizes the frequency and interval of mobile device scans while not impacting the ability of the devices to seamlessly move across disparate wireless networks is disclosed. More specifically the method involves creating a map of tower/network identifiers and channels of operation between different wireless networks. Using this information a mobile device can schedule its scans on multiple wireless interfaces in an energy-efficient and on-demand manner.
1 . A method for energy efficient scanning of multiple alternative wireless network interfaces to support handoffs by a mobile device among alternative wireless networks comprising;
said mobile device periodically scanning and storing a network map of tower/network identifiers and channels of operation of available alternative wireless network interfaces while located at particular wireless access locations; and,
said mobile device using said network map to schedule scanning on said available alternative wireless network interfaces only when said mobile device is at a particular wireless access location and is sure to find prospective channels on said alternative wireless network interfaces available for handoff.
2 . The method of claim 1 wherein said network map includes signal quality parameters determined during said periodic scanning that are used to determine availability for handoff.
3 . The method of claim 1 wherein a hysteresis timer is used to determine availability for handoff.