COMBINE is a system that facilitates collaborative downloading for multi-homed mobile devices.

Mobile devices are increasingly equipped with multiple network interfaces ― one set of interfaces for local connectivity (WLAN) and the another for wide-area connectivity (WWAN). Examples of WLAN include BlueTooth and Wi-Fi, and those of WWAN include GPRS, EDGE, and EV-DO. These two classes of interfaces offer an interesting tradeoff: the WWAN typically provides much wider coverage but the WLAN typically offers much higher data rates.

 To address this range-speed dichotomy, we propose a collaborative download mechanism, wherein a group of mobile nodes in close vicinity pool together their WWAN links, using the high-speed WLAN as the glue. Such collaboration can boost the effective data rate available to the individual nodes. Our work focuses on addressing a number of research challenges that arise in this context, including incentives for collaboration, fast and energy-efficient collaboration group formation, protocol mechanisms to enable deployment with little or no modification to the existing Internet infrastructure, and security and privacy. A position paper describing the research challenges to realizing collaborative downloading appeared at IEEE HotMobile 2007 and a full paper describing the system appeared at ACM MobiSys 2007.


Ganesh Ananthanarayan

Lenin Ravindranath Sivalingam

Venkat Padmanabhan

Chandu Thekkath