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A Detailed Look into Power Consumption of Commodity 60 GHz Devices
Get PDFThe millimeter-wave technology is emerging as an alternative to legacy 2.4/5 GHz WiFi, offering multi-Gigabit throughput. While a lot of attention has been paid recently to analyzing the performance of the 60 GHz technology and adapting it for indoor WLAN usage, the power consumption aspect has largely been neglected. Given that mobile devices are the next target for 60 GHz, any discussion about this technology is incomplete without considering power consumption. In this work, we present the first, to our best knowledge, detailed study of the power consumption of 60 GHz commodity devices. We evaluate the power and energy consumption of two standard-compliant 60 GHz wireless adapters in different operating states and under a number of different configurations. We also compare our results against 802.11ac and discuss power-performance tradeoffs for the two technologies.TRUEpu
Adaptive Schedulers for Deadline-Constrained Content Upload from Mobile Multihomed Vehicles
Get PDFDOI: 10.1109/LANMAN.2017.7972140We consider the practical problem of video surveillance in public transport systems, where security videos are stored onboard, and a central operator occasionally needs to access portions of the recordings. When this happens, the selected video must be uploaded within a deadline, possibly using multiple parallel wireless interfaces. Interfaces have different associated costs, related to tariffs charged by Mobile Network Operators (MNOs), energy consumption, data quotas, system load. Our goal is to choose which interfaces to use, and when, so as to minimize the cost of the upload while meeting the deadline, despite the unknown short-term variations in throughput. To achieve this goal, we first collect real traces of mobile uploads from vehicles for different MNOs. Examination of these traces confirms the unpredictability of the short-term throughput of wireless connections, and motivates the adoption of adaptive
schedulers with limited a-priori knowledge of the system status.
To effectively solve our problem, we devised a family of
adaptive algorithms, that we thoroughly evaluated using a trace-driven approach. Results show that our adaptive approach can effectively leverage the fundamental tradeoff between the total cost and the delivery time of content upload, despite unknown short-term variations in throughput.TRUEpu
Sociability-Driven Framework for Data Acquisition in Mobile Crowdsensing over Fog Computing Platforms for Smart Cities
Get PDFSmart cities exploit the most advanced information technologies like Internet of Things to improve and add value to existing public services. Having citizens involved in the process through mobile crowdsensing (MCS) techniques augments the capabilities of the platform without additional costs. In this paper, we propose a novel framework for data acquisition in MCS deployed over a fog computing platform which facilitates important operations like user recruitment and task completion. Proper data acquisition minimizes the monetary expenditure the platform sustains to recruit and compensate users and the energy they spend to sense and deliver data. We propose a new user recruitment policy called DSE (Distance, Sociability, Energy). The policy exploits three criteria: i) spatial distance between users and tasks, ii) user sociability, which is an estimate of the willingness of users to contribute to sensing tasks, and iii) remaining battery charge the devices. Performance evaluation is conducted in a real urban environment for a large number of participants with new metrics that assess the efficiency of the recruitment policy and the accuracy of task completion. Results reveal that the average number of recruited users improves by nearly 20% if compared to policies using only spatial distance as selection criterion.pu
Methods for revealing and reshaping the African Internet ecosystem as a case study for developing regions: From isolated networks to a connected continent
Get PDFWhile connecting end-users worldwide, the Internet increasingly promotes local development by making challenges much simpler to overcome, regardless of the field in which it is used: governance, economy, education, health, etc. However, African Network Information Centre (AfriNIC), the Regional Internet Registry (RIR) of Africa, is characterized by the lowest Internet penetration: 28.6% as of March 2017 compared to an average of 49.7% worldwide according
to the International Telecommunication Union (ITU) estimates [139]. Moreover, end-users experience a poor Quality of Service (QoS) provided at high costs. It is thus of interest to enlarge the
Internet footprint in such under-connected regions and determine where the situation can be improved.
Along these lines, this doctoral thesis thoroughly inspects, using both active and passive data analysis, the critical aspects of the African Internet ecosystem and outlines the milestones of a methodology that could be adopted for achieving similar purposes in other developing regions.
The thesis first presents our efforts to help build measurements infrastructures for alleviating the shortage of a diversified range of Vantage Points (VPs) in the region, as we cannot improve what we can not measure. It then unveils our timely and longitudinal inspection of the African interdomain routing using the enhanced RIPE Atlas measurements infrastructure for filling the lack of knowledge of both IPv4 and IPv6 topologies interconnecting local Internet Service Providers (ISPs). It notably proposes reproducible data analysis techniques suitable for the treatment of any set of similar measurements to infer the behavior of ISPs in the region. The results show a large variety of transit habits, which depend on socio-economic factors such as the language, the currency area, or the geographic location of the country in which the ISP operates. They indicate the prevailing dominance of ISPs based outside Africa for the provision of intracontinental paths, but also shed light on the efforts of stakeholders for traffic localization.
Next, the thesis investigates the causes and impacts of congestion in the African IXP substrate, as the prevalence of this endemic phenomenon in local Internet markets may hinder their growth. Towards this end, Ark monitors were deployed at six strategically selected local Internet
eXchange Points (IXPs) and used for collecting Time-Sequence Latency Probes (TSLP) measurements during a whole year. The analysis of these datasets reveals no evidence of widespread congestion: only 2.2% of the monitored links experienced noticeable indication of congestion, thus promoting peering. The causes of these events were identified during IXP operator interviews, showing how essential collaboration with stakeholders is to understanding the causes of performance degradations.
As part of the Internet Society (ISOC) strategy to allow the Internet community to profile the IXPs of a particular region and monitor their evolution, a route-collector data analyzer was then developed and afterward, it was deployed and tested in AfriNIC. This open source web
platform titled the “African” Route-collectors Data Analyzer (ARDA) provides metrics, which picture in real-time the status of interconnection at different levels, using public routing information available at local route-collectors with a peering viewpoint of the Internet. The results highlight that a small proportion of Autonomous System Numbers (ASNs) assigned by AfriNIC (17 %) are peering in the region, a fraction that remained static from April to September 2017
despite the significant growth of IXPs in some countries. They show how ARDA can help detect the impact of a policy on the IXP substrate and help ISPs worldwide identify new interconnection opportunities in Africa, the targeted region.
Since broadening the underlying network is not useful without appropriately provisioned services to exploit it, the thesis then delves into the availability and utilization of the web infrastructure serving the continent. Towards this end, a comprehensive measurement methodology is applied to collect data from various sources. A focus on Google reveals that its content infrastructure in Africa is, indeed, expanding; nevertheless, much of its web content is still served from the United States (US) and Europe, although being the most popular content source in many African countries. Further, the same analysis is repeated across top global and regional websites, showing that even top African websites prefer to host their content abroad. Following that, the primary bottlenecks faced by Content Providers (CPs) in the region such as the lack of peering between the networks hosting our probes and poorly configured DNS resolvers are explored to outline proposals for further ISP and CP deployments.
Considering the above, an option to enrich connectivity and incentivize CPs to establish a presence in the region is to interconnect ISPs present at isolated IXPs by creating a distributed IXP layout spanning the continent. In this respect, the thesis finally provides a four-step interconnection scheme, which parameterizes socio-economic, geographical, and political factors using public datasets. It demonstrates that this constrained solution doubles the percentage of continental intra-African paths, reduces their length, and drastically decreases the median of their Round Trip Times (RTTs) as well as RTTs to ASes hosting the top 10 global and top 10 regional Alexa websites. We hope that quantitatively demonstrating the benefits of this framework will incentivize ISPs to intensify peering and CPs to increase their presence, for enabling fast, affordable, and available access at the Internet frontier.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Mitigating Lateral Interference: Adaptive Beam Switching for Robust Millimeter-Wave Networks
Get PDFPutting into practice "pseudo-wire" links in wireless millimeter-wave (mm-wave) networks is challenging due to the significant side lobes of consumer-grade phased antenna arrays. Nodes should steer their beams such that they maximize the signal gain but also minimize interference from lateral directions via both their main lobe and their side lobes. Most importantly, interference can be caused by parallel operation of incompatible standards such as WiGig and IEEE 802.11ad and may change very fast. This timing requirement, prevents the use of existing beam switching solutions to mitigate interference. In this paper, we present an adaptive beam switching (ABS) mechanism that can deal with the above timescale issue in rapidly changing interference scenarios. Instead of performing a full beam sweep, the key idea is to only probe beampatterns at the receiver which are likely to avoid interference. In contrast to earlier work, our mechanism does not require any location information nor a detailed shape of the beampatterns. We exploit similarities among side lobes of beampatterns to estimate the performance of all beampatterns without sending extensive probes. To evaluate our mechanism in practice, we develop a customized research platform that allows us to control the beam-selection on low-cost IEEE 802.11ad routers. Experimental results with WiGig transceivers as interference source show that our adaptive beam switching mechanism achieves an average throughput gain of 60% and decreases the training time by 82.4% compared to the original IEEE 802.11ad behavior.TRUEpu
"Is Our Children's Apps Learning?" Automatically Detecting COPPA Violations
Get PDFIn recent years, a market of games and learning apps for children has flourished in the mobile world. Many of these often ``free'' mobile apps have access to a variety of sensitive personal information about the user, which app developers can monetize via advertising or other means. In the United States, the Children's Online Privacy Protection Act (COPPA) protects children's privacy, requiring parental consent to the use of personal information and prohibiting behavioral advertising and online tracking.
In this work, we present our ongoing effort to develop a method to automatically evaluate mobile apps' COPPA compliance. Our method combines dynamic execution analysis (to track sensitive resource access at runtime) with traffic monitoring (to reveal private information leaving the device and recording with whom it gets shared, even if encrypted). We complement empirical technical observations with legal analysis of the apps' corresponding privacy policies.
As a proof of concept, we scraped the Google Play store for apps distributed in categories specifically targeting users under than 13 years of age, which subjects these products to COPPA's regulations. We automated app execution on an instrumented version of the Android OS, recording the apps' access to and transmission of sensitive information. To contextualize third parties (e.g., advertising networks) with whom the apps share information, we leveraged a crowdsourced dataset collected by the Lumen Privacy Tool (formerly Haystack), an Android-based device-local traffic inspection platform. Our effort seeks to illuminate apps' compliance with COPPA and catalog the organizations that collect sensitive user information. In our preliminary results, we find several likely COPPA violations, including omission of prior consent and active sharing of persistent identifiers with third-party services for tracking and profiling of children. These results demonstrate our testbed's capability to detect different types of possible violations in the market for children's apps.TRUEpu
Efficient FIB Representations on Distributed Platforms
Get PDFThe Internet routing ecosystem is facing substantial scalability challenges due to continuous, significant growth of the state represented in the data plane. Distributed switch architectures introduce additional constraints on efficiency of implementations from both lookup time and memory footprint perspectives. In this work we explore efficient FIB representations in common distributed switch architectures. Our approach introduces substantial savings in memory footprint transparently for existing hardware. Our results are supported by an extensive simulation study on real IPv4 and IPv6 FIBs.pu
Anchorless Underwater Acoustic Localization
Get PDFWe consider the problem of estimating the trajectory of a submerged source emitting acoustic signals without using any anchor nodes or receiving array. This approach is required for several applications, including the localization of acoustic sources such as marine mammals or underwater vehicles, for which the cost of covering a broad area with multiple receivers would be excessively high. Since multi-lateration is impossible in this scenario, we perform localization by incorporating bathymetry information. Specifically, we assume that the receiver retains knowledge of the environmental parameters that affect the signal propagation, and that the bathymetry of the area is sufficiently diverse to induce distinguishable channel impulse responses for different source locations. Our method compares the channel estimates obtained from the received acoustic signals against a database of channel responses, pre-computed through an acoustic ray tracing model. The set of possible node locations that result are then organized in trellis form to obtain a final estimate of the source's trajectory via a path tracking method similar to the Viterbi algorithm. Our results show that the proposed approach can estimate node locations and paths with very small error, provided that the receiver has sufficiently accurate and up-to-date environmental information.TRUEpu
mm-View: Obtaining Real-Time Lower Layer Information of Commercial Off-The-Shelf 60 GHz Hardware
Get PDFThe lower layer characteristics of 60 GHz wireless networks impact the entire protocol stack. This includes effects such as sudden link failure due to blockage, high packet loss due to deafness, or suboptimal transmit rates due to antenna misalignment. To understand the resulting behaviors at the upper layers, it is key to have access to lower layer information. At the time of writing, 60 GHz experimentation hardware is either limited in terms of bandwidth, real-time capability, or does not support a full stack. In contrast, commercial off-the-shelf (COTS) hardware covers all of the above features but is a black box regarding the lower layers. Our demo exploits hidden monitoring capabilities of a certain COTS device which has become popular in the 60 GHz research community. The demo allows conference attendees to interact with 60 GHz links and observe how this impacts lower layer parameters. Moreover, the demo shows how such interactions relate to the performance at the upper layers.TRUEpu
Leveraging the Near-Far Effect for Improved Spatial-Reuse Scheduling in Underwater Acoustic Networks
Get PDFWe present a spatial reuse resource allocation for underwater acoustic networks that organizes communications so as to avoid destructive collisions. One prime source of collisions in underwater acoustic networks is the so called near-far effect, where a node located farther from the receiver is jammed by a closer node. While common practice considers such situation as a challenge, in this paper we consider it as a resource, and use it to increase network throughput of spatial reuse time-division multiple access. Our algorithm services two types of communications: 1) contention-free and 2) opportunistic. Our objective is to miximize the time slot allocation while guaranteeing a minimum per-node packet transmission rate. The result is an increase in number of contention-free packets received and a decrease in the scheduling delay of opportunistic packets. Numerical results show that, at a slight cost in terms of fairness, our scheduling solutions achieve higher throughput and lower transmission delay than benchmark spatial-reuse scheduling protocols. The results are verified in a field experiment conducted in the Garda Lake, Italy, where we demonstrated our solution using off-the-shelf acoustic modems. To allow the reproducibility of our results, we publish the implementation of our proposed algorithm.pu