Improving hard handover in HBR IP micro mobility access networks employing tree based topologies

Abstract

In IP based wireless access networks, the flow of packets to the mobile host (MH) is diverted at the cross-over node (CoN) to the new location of the MH in order to reduce handover delay and packet loss. As the depth of the network increases so does the round trip time to the CoN, in the worst case this is the time to the gateway or root node of the domain. This paper proposes an architectural modification to micro mobility protocols employing virtual or static tree topologies such as cellular IP (CIP). We propose an architectural extension to the path update process by adding multi-homed base stations (MHOBS) at certain points in the wireless access network where the path update delay becomes severe. There are two situations where this may arise. The first is where the path update is due to a distant gateway, or other CoN, as a result of an increase in the depth of the topology. The second situation is more likely to arise, with virtual tree topologies on mesh networks, when the new path, between new base station (BS) and the CoN, is longer than the old path to the old BS. The path update minimization proposed here eliminates the effect of path update delay at these points in the network, and consequently reduces packet loss due to the handover process.