Handover management based on the number of retries for VoIP on WLANs

Ubiquitous networks enabling access by mobile nodes (MNs) at anytime and at any location will consist of several different WLANs, so that it is very, likely that the MN will traverse several hotspots during communication. Thus, a single communication can experience several handovers between WLANs, during which the quality of the communication may be degraded due to packet loss. In the present study, we attempt to develop an effective handover management scheme for VoIP communication in which the quality is sensitive to packet loss. For this purpose, we propose a handover management scheme that employs a transport protocol that supports multiple connections for VoIP communication and that makes handover decisions based upon a new criterion, i.e., the number of retries experienced by a data frame. The proposed handover management scheme minimizes packet loss, as well as redundant traffic due to parallel transfer of identical packets, by predicting the occurrence of packet loss in advance based on the number of retries and properly selecting a single-path or multi-path by examining the communication quality on the wireless link.