Youngki Lee, Younghyun Ju, Chulhong Min, Seungwoo Kang, Inseok Hwang, Junehwa Song
Mobile applications that sense continuously, such as location monitoring, are emerging. Despite their usefulness, their adoption in real-world deployment situations has been extremely slow. Many smartphone users are turned away by the drastic battery drain caused by continuous sensing and processing. Also, the extractable contexts from the phone are quite limited due to its position and sensing modalities. In this paper, we propose CoMon, a novel cooperative ambience monitoring platform, which newly addresses the energy problem through opportunistic cooperation among nearby mobile users. To maximize the benefit of cooperation, we develop two key techniques, (1) continuity-aware cooperator detection and (2) benefit-aware negotiation. The former employs heuristics to detect cooperators who will remain in the vicinity for a long period of time, while the latter automatically devises a cooperation plan that provides mutual benefit to cooperators, while considering running applications, available devices, and user policies. Through continuity- and benefit-aware operation, CoMon enables applications to monitor the environment at much lower energy consumption. We implement and deploy a CoMon prototype and show that it provides significant benefit for mobile sensing applications.
A link to the full paper: http://nclab.kaist.ac.kr/papers/Conference/lee12mobisys.pdf
Public Review uploaded by lzhong:
This public review was prepared by Li-Shiuan Peh.
The proposed Comon system tackles the problem of sharing sensor information between phones in the vicinity based on context, in order to save mobile phone energy. It first motivates the problem with an in-depth analysis of mobility traces, arguing that people (and thus their phones) are in proximity for sufficient duration of time to make this feasible, a nice touch that helps to lend credence to the proposal.
The presented Comon system is a very ambitious and system that has been built end-to-end, and demonstrated substantial energy savings through several deployments.
Overall, the paper's novelty is exciting, and it takes a solid step towards collaborative sensing. However, there are several gaps that still have to be addressed before this interesting direction is fully adopted in society. First, as with any collaborative solution, a critical mass of participants is necessary, before practical adoption. Second, again characteristic of collaborative solutions, privacy is a concern. The paper addresses this to some extent suggesting that collaborative sensing amongst a person's social network is common and more likely to be acceptable.
As we move towards very dense populations of phones in metropolitan cities, and as social networking applications brush away critics' views of privacy concerns, it is not difficult to imagine pervasive collaborative sensing. This work's strong system demonstration will help pave the way.
We appreciate Prof. Li Shiuan Peh, for her valuable review and comments.
The core novelty of CoMon is that it tackles the severe energy problem of continuous sensing applications through in-situ cooperation between nearby mobile users (mostly between acquaintances). As an initial step, we showed that cooperation opportunities are prevailing through in-depth analysis on peoples’ time use data and mobility traces, showing that the cooperation approach has enough potential to achieve energy benefit in terms of cooperation duration. In the paper, the analysis results are presented to convince the enough chances for cooperative sensing while the study has more significant implications. Briefly speaking, it is essential to newly turn our eyes upon the prevailing situation of daily social activities among multiple co-located people when designing future mobile devices, systems, and applications; note that current smartphones and applications are mostly limited to personal use or remote communications, not targeting this very interesting and also prevailing in-situ social situations.
Elaborating the cooperation approach, we built a novel platform for cooperative sensing and context monitoring, named CoMon. We attempted to build an end-to-end working system, as our successive efforts to build an underlying context monitoring platform, enabling applications to have context awareness without worrying about the complications in context inference and resource managements. As CoMon is a highly visionary and complex system, we faced into a broad range of challenges to tackle while developing the platform. In the paper, we focused on several key issues to ensure energy benefits through cooperation while there are other issues to be further addressed for the successful adoption of CoMon system and its directions. For example, wide social adoption and privacy would be the important issues to be studied, as mentioned in the public review by Prof. Peh.
Participation Regarding the massive participation for practical adoption, we believe that CoMon is more advantageous over other collaborative applications such as city-scale participatory-sensing applications or crowd-sourcing applications. As noticed in the paper, CoMon could achieve significant energy benefit through cooperation among acquainted mobile users in their vicinity. Accordingly, it would be quite effective even when the system is deployed only within a small social group, e.g., close friends, families and coworkers who spend time together quite much. As people in close social groups often interact quite actively, installing a common system together is much less challenging, comparing to those requiring the large-scale deployment; note that many participatory sensing systems start to be effective only after quite massive number of anonymous users utilize the applications concurrently. Surely, CoMon will be more effective if the system is widely adopted by massive number of users, and cooperation is possible almost all-the-time, even among some strangers. It is still an open question, how we can promote the system to be fully adopted by the critical mass of participants.
Privacy When it comes to “context”, privacy is always one of the critical concerns. Many mobile users are worried vaguely or dislike if their location or any other contextual information is leveraged by smartphone OS or applications. As CoMon shares user contexts with nearby users for energy benefit, the privacy concerns are likely to be aggravated.
To be optimistic, we believe that privacy concerns might be relatively mitigated in CoMon environments, where the cooperators are physically in the same contexts and know with each other in most cases. There have been some initial studies on sharing of contexts and phones that partially support such arguments. For example, a study on location sharing supports that people are less conscious of sharing their locations when they are closeby ( in the paper’s reference). A study on phone sharing shows that sharing is more acceptable with those in close social relations such as families, friends, or colleagues . To be conservative, however, privacy concerns largely depend on perception and sensitivity of users, and users’ varying situations/contexts, usefulness of applications leveraging the contexts, etc . As an initial solution, CoMon aims to provide users with the controllability and visibility on the sharing of their contexts through the privacy rules governing the access to their contexts from cooperators. We acknowledge that the rule-based restriction only addresses some basic concerns on the privacy; it is still an open research question requiring further in-depth studies.