A route optimization scheme for mobile hosts within a cellular IP access network

Abstract

The Mobile IP was developed in Internet Engineering Task Force (IETF) to support mobility under regular IP network. However, if a mobile host handoffs frequently, the performance degradation of the Mobile IP is inevitable. The Cellular IP is one of the proposals to solve this problem. The Cellular IP is a simple and efficient micro mobility protocol that supports seamless mobility, passive connectivity and paging. These features of the Cellular IP are fundamental to improving scalability, minimizing power consumption, and delivering suitable service quality to mobile hosts. In spite of some obvious advantages, the Cellular IP has some limitations when a user communicates with another who resides in the same Cellular IP access network. The Cellular IP is defined as that all data packets, transmitted by a mobile host, are first forwarded to a gateway regardless of the destination address. After then, the data packets are forwarded to the receiver by a hop-by-hop method. If the sender and the receiver are located in the same Cellular IP access network, there is a high possibility of route duplication between the path from the sender to the gateway and the route from the gateway to the receiver. Path duplication means that resources of the base stations and network are consumed unnecessarily because of the routing policy. In this paper, we propose a route optimization scheme preventing path duplication when a user communicates with another within the same Cellular IP access network. In our scheme, the BS checks whether a downlink path, which can reach a receiver, exists or not by means of cache information, whenever packets are received. If it finds a downlink path, the packets are directly forwarded through the downlink path. Consequently, the BS builds and sends a $\emph{pseudo data}$ packet to the gateway in order to refresh cache information on uplink neighbors. We have implement the proposed scheme as an extension to the Cellular IP 1.1 distribution conf...