Abstract
Asymmetric access networks with downlink bandwidth 10-1000 times higher than uplink bandwidth are common, and upgrading these links may not be economically feasible in many usage scenarios. In this paper, we design, implement, and evaluate a parameterized Asymmetric Communication Layer (ACL) protocol that capitalizes the otherwise idling downlink bandwidth to boost the uplink goodput. The ACL protocol is different from existing techniques such as caching, protocol-independent redundancy elimination, WAN optimization, and online compression algorithms, because the ACL protocol is the first concrete network protocol to increase uplink goodput using downlink bandwidth. We implement the ACL protocol in ns-2 simulator, and conduct extensive simulations using synthetic traffic traces. The simulation results show the potential of the ACL protocol: compared to plain TCP/IP, 40-90% uplink goodput gain is possible. Users can also trade the goodput gain for lower delivery delay, as low as 1 RTT, or lower downlink payload amount, as low as 2.13 times of the actual data size. We also conduct a trace-driven simulation using a one-week real traffic trace of a Web server. We observe 24% uplink goodput gain, which shows the practicality of the ACL protocol. © 2012 IEEE.