Seamnless Handover for Hotspot Network Using Adaptive Flow Control Method

We have proposed hotspot network based on layer 2 forwarding for seamless handover. Key functions of the proposed hotspot network are movement notification packet sending for changing forwarding path and adaptive flow control at handover for keeping throughput. A mobile terminal sends the movement notification packet in order to change address table in nodes of the hotspot network after changing connection from previous access point to new access point. To realize adaptive flow control, MT controls transmission control protocol (TCP) offered window size. The mobile terminal closes the offered window before handover and opens the window after handover. We have evaluated performance of the proposed network using network test bench. IEEE 802.11b modems were used as wireless interfaces. The degradation of throughput at handover was reduced compared with that of conventional method without adaptive flow control