407 research outputs found
Quality of Information in Mobile Crowdsensing: Survey and Research Challenges
Smartphones have become the most pervasive devices in people's lives, and are
clearly transforming the way we live and perceive technology. Today's
smartphones benefit from almost ubiquitous Internet connectivity and come
equipped with a plethora of inexpensive yet powerful embedded sensors, such as
accelerometer, gyroscope, microphone, and camera. This unique combination has
enabled revolutionary applications based on the mobile crowdsensing paradigm,
such as real-time road traffic monitoring, air and noise pollution, crime
control, and wildlife monitoring, just to name a few. Differently from prior
sensing paradigms, humans are now the primary actors of the sensing process,
since they become fundamental in retrieving reliable and up-to-date information
about the event being monitored. As humans may behave unreliably or
maliciously, assessing and guaranteeing Quality of Information (QoI) becomes
more important than ever. In this paper, we provide a new framework for
defining and enforcing the QoI in mobile crowdsensing, and analyze in depth the
current state-of-the-art on the topic. We also outline novel research
challenges, along with possible directions of future work.Comment: To appear in ACM Transactions on Sensor Networks (TOSN
Tit-for-Token: fair rewards for moving data in decentralized storage networks
Centralized data silos are not only becoming prohibitively expensive but also
raise issues of data ownership and data availability. These developments are
affecting the industry, researchers, and ultimately society in general.
Decentralized storage solutions present a promising alternative. Furthermore,
such systems can become a crucial layer for new paradigms of edge-centric
computing and web3 applications. Decentralized storage solutions based on p2p
networks can enable scalable and self-sustaining open-source infrastructures.
However, like other p2p systems, they require well-designed incentive
mechanisms for participating peers. These mechanisms should be not only
effective but also fair in regard to individual participants. Even though
several such systems have been studied in deployment, there is still a lack of
systematic understanding regarding these issues. We investigate the interplay
between incentive mechanisms, network characteristics, and fairness of peer
rewards. In particular, we identify and evaluate three core and up-to-date
reward mechanisms for moving data in p2p networks: distance-based payments,
reciprocity, and time-limited free service. Distance-based payments are
relevant since libp2p Kademlia, which enables distance-based algorithms for
content lookup and retrieval, is part of various modern p2p systems. We base
our model on the Swarm network that uses a combination of the three mechanisms
and serves as inspiration for our Tit-for-Token model. We present our
Tit-for-Token model and develop a tool to explore the behaviors of these
payment mechanisms. Our evaluation provides novel insights into the functioning
and interplay of these mechanisms and helps. Based on these insights, we
propose modifications to these mechanisms that better address fairness concerns
and outline improvement proposals for the Swarm network
Using Tuangou to reduce IP transit costs
A majority of ISPs (Internet Service Providers) support connectivity to the entire Internet by transiting their traffic via other providers. Although the transit prices per Mbps decline steadily, the overall transit costs of these ISPs remain high or even increase, due to the traffic growth. The discontent of the ISPs with the high transit costs has yielded notable innovations such as peering, content distribution networks, multicast, and peer-to-peer localization. While the above solutions tackle the problem by reducing the transit traffic, this paper explores a novel approach that reduces the transit costs without altering the traffic. In the proposed CIPT (Cooperative IP Transit), multiple ISPs cooperate to jointly purchase IP (Internet Protocol) transit in bulk. The aggregate transit costs decrease due to the economies-of-scale effect of typical subadditive pricing as well as burstable billing: not all ISPs transit their peak traffic during the same period. To distribute the aggregate savings among the CIPT partners, we propose Shapley-value sharing of the CIPT transit costs. Using public data about IP traffic of 264 ISPs and transit prices, we quantitatively evaluate CIPT and show that significant savings can be achieved, both in relative and absolute terms. We also discuss the organizational embodiment, relationship with transit providers, traffic confidentiality, and other aspects of CIPT
A reactive algorithm for deducing nodal forwarding behavior in a multihop ad hoc wireless network in the presence of errors
A novel algorithm is presented to deduce individual nodal forwarding behavior from standard end to end acknowledgments. The algorithm is based on a well-established mathematical method and is robust to network related errors and nodal behavior changes. The proposed solution was verified in a network simulation, in which it performed well in a difficult environment and achieved sound results
Offloading Content with Self-organizing Mobile Fogs
Mobile users in an urban environment access content on the internet from
different locations. It is challenging for the current service providers to
cope with the increasing content demand from a large number of collocated
mobile users. In-network caching to offload content at nodes closer to users
alleviate the issue, though efficient cache management is required to find out
who should cache what, when and where in an urban environment, given nodes
limited computing, communication and caching resources. To address this, we
first define a novel relation between content popularity and availability in
the network and investigate a node's eligibility to cache content based on its
urban reachability. We then allow nodes to self-organize into mobile fogs to
increase the distributed cache and maximize content availability in a
cost-effective manner. However, to cater rational nodes, we propose a coalition
game for the nodes to offer a maximum "virtual cache" assuming a monetary
reward is paid to them by the service/content provider. Nodes are allowed to
merge into different spatio-temporal coalitions in order to increase the
distributed cache size at the network edge. Results obtained through
simulations using realistic urban mobility trace validate the performance of
our caching system showing a ratio of 60-85% of cache hits compared to the
30-40% obtained by the existing schemes and 10% in case of no coalition
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