The rapidly growing availability of mobile devices has accelerated the development of real-time multimedia communication applications. This growth has resulted in an increased demand for high bandwidth (but short ranged) Wi-Fi access points (APs). But as a mobile device moves between APs, delays can be introduced due to handoff issues. This technology is a method for reducing AP handoff delays when mobile devices move between AP ranges. Mobile devices enabled with this technology stores network information regarding surrounding APs, ranked by signal strength. If an AP is not found from the local cache, the device may obtain information regarding APs from nearby mobile devices via a multicast request.
prevents perceptible handoff time interruptions of real-time communication.
When devices move between one AP to another, a handoff must be performed to end communication with the former and continue communication with the latter. Currently, such handoffs cause a noticeable interruption in any ongoing real-time communication sessions. By requiring that every device that receives a multicast request populate its AP and subnet cache, even when it does not immediately need the data, this technology can significantly reduce the net handoff time of devices. Enabling assisting devices to obtain new IP addresses on behalf of other devices before actual handoff occurs also prevents the typically slow IP address acquisition process from unduly contributing to handoff time. This technology also provides authentication and security measures in addition to those natively supported by the wireless network to prevent exploitation of the cooperative roaming mechanism.
This technology has been implemented by modifying several open-source wireless software packages and successfully tested on an 802.11b wireless network using multiple mobile devices and access points.
Patent Pending (US 20080285520)
Tech Ventures Reference: IR M06-027
