Practicalizing Delay-Tolerant Mobile Apps with Cedos YoungGyoun Moon, Donghwi Kim, Younghwan Go, Yeongjin Kim, Yung Yi, Song Chong, and KyoungSoo Park Department of Electrical Engineering, KAIST Daejeon, Republic of Korea {ygmoon, dhkim, yhwan}@ndsl.kaist.edu,
[email protected], {yiyung, songchong}@kaist.edu,
[email protected] ABSTRACT 1. INTRODUCTION Delay-tolerant Wi-Fi offloading is known to improve overall mo- Wi-Fi has become the most popular secondary network interface bile network bandwidth at low delay and low cost. Yet, in reality, for high-speed mobile Internet access on mobile devices. Many we rarely find mobile apps that fully support opportunistic Wi-Fi mobile apps support the “Wi-Fi only” mode that allows the users to access. This is mainly because it is still challenging to develop shun expensive cellular communication while enjoying high band- delay-tolerant mobile apps due to the complexity of handling net- width and low delay. In addition, cellular ISPs are actively de- work disruptions and delays. ploying Wi-Fi access points (APs) to further increase the mobile In this work, we present Cedos, a practical delay-tolerant mobile Internet access coverage [1, 2, 3]. network access architecture in which one can easily build a mo- However, current Wi-Fi usage is often statically bound to the lo- bile app. Cedos consists of three components. First, it provides a cation of mobile devices. While this “on-the-spot” Wi-Fi offloading familiar socket API whose semantics conforms to TCP while the is still effective, recent studies suggest that one can further extend underlying protocol, D2TP, transparently handles network disrup- the benefit of Wi-Fi access if we allow delay tolerance between net- tions and delays in mobility.