A New TCP Reordering Mechanism for Downward Vertical Handover

In integrated WLAN and cellular networks, a downward vertical handover (DVHO) causes an abrupt change so that packets which are transmitted through both networks can be out of ordered. Reordering problem triggers unnecessary fast retransmission causing throughput degradation. Thus, we propose a TCP reordering mechanism for DVHO, that suppresses unnecessary retransmissions due to the duplicate acknowledgements (dupacks). The simulation shows that the proposed TCP achieves better performance compared with nodupack with SACK.