Guest Editorial: Special Section on Outstanding Papers from MobiSys 2011

Abstract

EACH year, the International Conference on Mobile Systems, Applications, and Services, or MobiSys as it is more commonly known, publishes a selection of cuttingedge research papers in mobile computing. MobiSys takes a broad systems perspective of mobile computing. The papers presented at the 2011 conference in June near Washington, DC ranged from smartphones to energy-efficiency, aspects of security, sensor networks and wireless protocols, and mobile applications and services. This special section brings to you revised versions of highly-ranked papers from MobiSys 2011. The conference was very competitive, with 25 papers being selected from 141 submissions in 2011. From the accepted papers, the PC chairs further selected three of the top papers as judged by the PC reviews and invited the authors of these papers to submit a revised paper to the IEEE Transactions on Mobile Computing. The three papers are a diverse set, and they offer you a glimpse into what is exciting in mobile computing today, as well as the different kinds of research that are presented at MobiSys. The first paper in the set is “Leveraging Smartphone Cameras for Collaborative Road Advisories,” by Emmanouil Koukoumidis, Margaret Martonosi, and LiShiuan Peh. In this paper, we learn about a mobile computing application that will advise the driver of a car to slow down or speed up in order to smoothly sail through green traffic lights, rather than wait at red traffic lights. What is new here? The work leverages the rich sensing capabilities of smartphones that make them such a compelling platform. It is not simply a GPS system that receives signal timing information from traffic signal controllers. Rather, placing the mobile on the windshield allows its camera to capture images that are analyzed in real-time to detect the phase of upcoming traffic lights. Information from all sources, including measurements of other nearby participants, is used to estimate traffic signal timings and make recommendations to the driver. As is typical for MobiSys, the system has been prototyped, and the paper reports on how well it works in small scale tests. In “Chameleon: A Color-Adaptive Web Browser for Mobile OLED Displays,” by Mian Dong and Lin Zhong, we shift focus from new mobile applications to the energy consumption of mobile displays. It is well known that the display is a substantial consumer of energy in mobile devices. In this work, Dong and Zhong explore the energy tradeoffs of OLED (Organic Light Emitting Diode) displays, which require no backlight but may be expensive in terms of energy to display bright images. Their answer is a system that targets web browsing to transform the colors of images in real time, shifting them from pixel values that are energyexpensive to alternative choices that are legible yet less expensive in terms of energy. An evaluation with a prototype and field trials shows both the potential to significantly extend battery life and a system that is valued by users. For the last paper of the set, we return to classic problems of mobile communications. In “Avoiding the Rush Hours: WiFi Energy Management via Traffic Isolation,” Justin Manweiler and Romit Roy Choudhury explore the latest in a series of designs to lower the amount of energy that mobile devices need to spend to communicate via 802.11. Standard techniques for power saving (such as 802.11 Power Save Mode) are assumed as a baseline. The problem is that the ever higher density of 802.11 APs (access points) tends to increase power consumption even with traditional power-saving designs. This is because clients will have to share the channel with a larger number of other clients and APs, and hence remain in an active state for longer periods of time to receive a burst of power save mode packets. Manweiler and Choudhury tackle this problem by decorrelating the cycles of overlapping APs, thus allowing the clients of one AP to sleep while the clients of another AP are awake. When prototyped and tested on real mobile applications, this design can greatly reduce the energy needed to power the network interface. We trust you will enjoy these papers. IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. 11, NO. 5, MAY 2012 705