Leadership maintenance in group-based location management scheme

In a mobile environment, location management is fundamental in supporting location-dependent applications. It is crucial to reduce the communication overhead in location management, due significantly to the costly uplink traffic for mobile hosts reporting their location to the server. To reduce uplink traffic, the group-based location management scheme exploits the spatial locality of mobile hosts to generate an aggregated location update from a group leader for group members agglomerated through a dynamic clustering algorithm. Due to the mobility of group members, a leader may be decoupled from a group voluntarily or involuntarily. An intuitive approach to address leader departure is to re-execute the clustering algorithm among leaderless group members. However, system performance may suffer, due to the absence of a group leader for a period. In this paper, a leadership maintenance scheme is designed based on the notion of a secondary leader, which is ready for assuming the role of a primary leader. The turnover activation policy identifies endangered primary leader and triggers the turnover procedure, which involves host interaction in leadership handover from the primary to secondary leader. Simulation study shows that our leadership maintenance scheme is effective to further reduce the costly uplink traffic and aggregated cost in the group-based location management scheme.