UDA: Fast transport protocol for D2D networks over WiFi

In this paper we present a new and efficient application level transport protocol UDA (UDP-based Delayed ACK) specially designed for device-to-device (D2D) networks operating over WiFi. Although WiFi speeds have increased manifold over the past few years, TCP performance over WiFi has not seen a commensurate improvement due to various overheads. One major overhead is caused by the cross-layer interaction of TCP and the WiFi MAC. Essentially TCP Data packets and TCP ACKs compete for the same half-duplex WiFi channel, thus greatly reducing TCP throughput. To overcome this problem, UDA employs a window-based congestion control protocol similar to TCP but adaptively reduces the number of acknowledgement packets. We demonstrate that UDA outperforms conventional TCP in terms of throughput by as much as 50% in a 2-hop WiFi testbed.