The study of signal strength threshold for VoIP handoff process in 802.11g/n networks

In standard IEEE 802.11 based systems, when the wireless client migrates away from the radio range of the currently associated Access Point (AP), network applications temporarily loose connectivity till the client is able to re-associate itself with a new AP. The delay that occurs during the break-off interval can vary from a few hundreds of microseconds to a few seconds. However, delay sensitive applications such as Voice over IP (VoIP) or streaming multimedia applications usually are unable to tolerate such long connectivity delays that fall beyond the range of 50-200 ms. This results in dropped calls or frozen video frames. To improve the deficiency, this paper proposes the preliminary study of managing the signal strength threshold to minimize handoff time by investigating the effect of changing the threshold at AP. Although different solutions are available in the literature, most of them proposed changes that were outside the purview of the current 802.11 standards. Our study requires no additional support from the network. The outcome of this paper indicates the good insight of using the signal strength threshold to control the handoff time for VoIP application.