A dummy segment based bandwidth probing technique to enhance the performance of TCP over heterogeneous networks

In mobile environments, the fundamental challenge upon a handoff phenomenon consists in an efficient probing of the availability of the new network resources and an appropriate rate adjustment in the new network cell. This paper proposes the usage of low-priority dummy packets to probe the availability of the new network resources. Indeed, when a mobile node enters a cell overlapping area and is about to change its point-of-attachment to the network, two connections are simultaneously set between the mobile node and the sender: one through the old point-of-attachment and another through the new one. The sender transmits actual data through the old connection. Meanwhile, it sends dummy segments through the new connection to verify the bandwidth availability of the new network. The proposed scheme is dubbed dummy segment based bandwidth probing (DSBP). The performance of the DSBP scheme is evaluated and compared with existing schemes through extensive simulations. The results show that DSBP substantially improves the system efficiency, reduces the number of packet drops, and makes better utilization of the network bandwidth.