An efficient TCP mechanism for Mobile IP handoffs

When using TCP over a mobile network, TCP responds to a handoff by invoking a congestion control algorithm thereby resulting in a degraded end-to-end performance in a mobile network. Furthermore, in Mobile IP handoffs, packets can be lost during movement detection and registration. These packet losses result in long communication pauses, and successive timeouts. Accordingly, to reduce packet losses during handoffs, two schemes are proposed, TCP-MD and TCP-R. TCP-MD can detect the movement of a mobile host early on, whereas TCP-R can force the source to freeze data transmission during registration. The proposed schemes maintain end-to-end TCP semantics, making it possible to interoperate fully with the existing infrastructure. Only a small change is required in the mobile host, plus the implementation is simple because some Mobile IP messages are used to notify the handoff, eliminating the need for any additional messages. Simulations confirmed that the proposed schemes can give an excellent performance in an environment where the mobile host experiences frequent handoffs