Mobile Data Offloading: How Much Can WiFi Deliver?

• Published in: IEEE/ACM transactions on networking Vol. 21; no. 2; pp. 536 - 550
• Main Authors: Lee, Kyunghan, Lee, Joohyun, Yi, Yung, Rhee, Injong, Chong, Song
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-04-2013; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cities and towns; Deadlines; Delay; Delayed transmission; experimental networks; Gain; IEEE 802.11 Standards; Mathematical analysis; Mobile communication; Mobile computing; mobile data offloading; mobility; Networks; Servers; Simulation; Statistics; Studies; Traffic engineering; Traffic flow; Wireless networks
• ISSN: 1063-6692; 1558-2566
• DOI: 10.1109/TNET.2012.2218122

This paper presents a quantitative study on the performance of 3G mobile data offloading through WiFi networks. We recruited 97 iPhone users from metropolitan areas and collected statistics on their WiFi connectivity during a two-and-a-half-week period in February 2010. Our trace-driven simulation using the acquired whole-day traces indicates that WiFi already offloads about 65% of the total mobile data traffic and saves 55% of battery power without using any delayed transmission. If data transfers can be delayed with some deadline until users enter a WiFi zone, substantial gains can be achieved only when the deadline is fairly larger than tens of minutes. With 100-s delays, the achievable gain is less than only 2%-3%, whereas with 1 h or longer deadlines, traffic and energy saving gains increase beyond 29% and 20%, respectively. These results are in contrast to the substantial gain (20%-33%) reported by the existing work even for 100-s delayed transmission using traces taken from transit buses or war-driving. In addition, a distribution model-based simulator and a theoretical framework that enable analytical studies of the average performance of offloading are proposed. These tools are useful for network providers to obtain a rough estimate on the average performance of offloading for a given WiFi deployment condition.