IEEE 802.11 link-layer forwarding for smooth handoff

In this paper, we present a link-layer packet forwarding scheme to reduce packet losses during a handoff in IEEE 802.11 WLAN. Through a novel scheme utilizing buffer and image queues in the device driver, the scheme is able to recover most packets that would otherwise be lost during the handoff, including those held in the network interface card. Our experimental results from a test-bed show that the proposed scheme can eliminate or significantly reduce the packet losses in UDP traffic, and help preserve throughput for TCP traffic when the retransmission time out (RTO) is large. To achieve the maximum benefit, we propose to apply the forwarding scheme adaptively depending on the traffic type.