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A vehicle-based measurement framework for enhancing whitespace spectrum databases 一种基于车辆的增强空白频谱数据库的测量框架
Tan Zhang, Ning Leng, Suman Banerjee
The present TV whitespace networks rely on spectrum occupancy databases to determine their operating channels. In this paper, we show that such databases cause non-negligible wastage of whitespace spectrum. We also report that whitespace channels can have very different quality due to interference from secondary devices and the leakage from TV broadcasts. Such disparity in channel quality is not captured by existing databases. We propose the use of spectrum measurements to overcome the above limitations of databases. In particular, we describe a system called V-Scope that leverages spectrum sensors on public vehicles to collect and report measurements from the road. These measurements are used as "anchor points" to construct various models to better determine whitespace spectrum, estimate its channel quality, and validate locations of primary and secondary devices. We have deployed our system on a single metro bus traveling across a mid-sized US city. Based on measurements collected at above 1 million locations over 120 square-km area, we find that a commercial database causes under-utilization of certain whitespace channels over a large area (up to 71% measured locations). Our system can reclaim this spectrum wastage at up to 59% locations, correctly selecting all the suitable whitespace channels at 72 -- 83% locations, and achieving a localization accuracy between 16 -- 27m.
目前的电视空白网络依赖于频谱占用数据库来确定其运行信道。在本文中,我们证明了这样的数据库会造成不可忽略的空白频谱浪费。我们还报告说,由于二次设备的干扰和电视广播的泄漏,空白信道的质量可能会有很大的不同。现有的数据库没有捕捉到这种信道质量的差异。我们建议使用光谱测量来克服数据库的上述限制。特别是,我们描述了一个称为V-Scope的系统,该系统利用公共车辆上的频谱传感器收集和报告道路上的测量结果。这些测量被用作“锚点”来构建各种模型,以更好地确定空白频谱,估计其信道质量,并验证主设备和辅助设备的位置。我们已经在一辆穿越美国中型城市的地铁公交车上部署了我们的系统。根据在120平方公里区域内超过100万个位置收集的测量数据,我们发现商业数据库导致大面积(高达71%的测量位置)某些空白通道的利用率不足。我们的系统可以在高达59%的位置回收这种频谱浪费,在72 - 83%的位置正确选择所有合适的空白信道,并实现16 - 27m之间的定位精度。
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引用次数: 72
Enhancing reliability to boost the throughput over screen-camera links 增强可靠性,提高屏幕-摄像机链路的吞吐量
Anran Wang, Shuai Ma, Chunming Hu, J. Huai, Chunyi Peng, G. Shen
With the rapid proliferation of camera-equipped smart devices (e.g., smartphones, pads, tablets), visible light communication (VLC) over screen-camera links emerges as a novel form of near-field communication. Such communication via smart devices is highly competitive for its user-friendliness, security, and infrastructure-less (i.e., no dependency on WiFi or cellular infrastructure). However, existing approaches mostly focus on improving the transmission speed and ignore the transmission reliability. Considering the interplay between the transmission speed and reliability towards effective end-to-end communication, in this paper, we aim to boost the throughput over screen-camera links by enhancing the transmission reliability. To this end, we propose RDCode, a robust dynamic barcode which enables a novel packet-frame-block structure. Based on the layered structure, we design different error correction schemes at three levels: intra-blocks, inter-blocks and inter-frames, in order to verify and recover the lost blocks and frames. Finally, we implement RDCode and experimentally show that RDCode reaches a high level of transmission reliability (e.g., reducing the error rate to 10%) and yields a at least doubled transmission rate, compared with the existing state-of-the-art approach COBRA.
随着配备摄像头的智能设备(如智能手机、平板电脑、平板电脑)的迅速普及,通过屏幕摄像头链路的可见光通信(VLC)作为一种新型的近场通信形式出现。这种通过智能设备进行的通信在用户友好性、安全性和无基础设施(即不依赖WiFi或蜂窝基础设施)方面具有很强的竞争力。然而,现有的方法大多侧重于提高传输速度,而忽略了传输可靠性。考虑到传输速度和可靠性之间的相互作用,为了实现有效的端到端通信,本文旨在通过提高传输可靠性来提高屏幕摄像机链路的吞吐量。为此,我们提出了RDCode,这是一种鲁棒的动态条形码,它支持一种新颖的包帧块结构。基于分层结构,我们设计了块内、块间和帧间三个层次的纠错方案,以验证和恢复丢失的块和帧。最后,我们实现了RDCode,实验表明RDCode达到了高水平的传输可靠性(例如,将错误率降低到10%),并且与现有的最先进的方法COBRA相比,产生了至少两倍的传输速率。
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引用次数: 85
Poster: a coarse-fine corner detection approach for two-dimensional barcode decoding 海报:一种二维条码解码的粗-精角检测方法
Changsheng Chen, W. Mow
Two-dimensional barcodes are widely used in mobile advertisement business, while their decoding performance is not always satisfactory under uncontrolled environments. The corner detection accuracy has been identified as a critical factor affecting the overall system performance. The standard barcode detector performs a candidate search in the binarized barcode image based on the rectangular shape of the barcode. Its performance is not very accurate due to the limited accuracy of the binarized image. In this work, we proposed a coarse-fine corner detection approach for locating the barcode region. It performs far more accurately than the standard barcode detection scheme while keeps the computational complexity affordable. Experimental results for high capacity barcodes show that the proposed detection scheme can extend the range of operation parameters, such as wider angles, and much lower the detection bit error rate, relative to the standard barcode decoder.
二维条形码在移动广告业务中应用广泛,但在非受控环境下,其解码性能并不理想。角点检测精度是影响系统整体性能的关键因素。标准条形码检测器根据条形码的矩形形状在二值化后的条形码图像中执行候选搜索。由于二值化图像的精度有限,其性能不是很准确。在这项工作中,我们提出了一种粗-精边角检测方法来定位条形码区域。它比标准的条形码检测方案执行得更准确,同时保持计算复杂性可承受。大容量条码的实验结果表明,与标准条码解码器相比,本文提出的检测方案可以扩展工作参数的范围,如更宽的角度,并大大降低检测误码率。
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引用次数: 6
Poster: a framework for instant mobile web browsing with smart prefetching and caching Poster:一个带有智能预取和缓存的即时移动网页浏览框架
Huan Huang, Hailong Sun, Guoqing Ma, Xu Wang, Xudong Liu
Mobile users often suffer from a slow page loading time due to intermittently connected wireless networks and increasing size of mobile Web pages. Although existing approaches of prefetching and caching are widely used to reduce the browsing latency, they may fail to work effectively because most Web page visits are singletons and the cache hit ratio is unsatisfying. In this work, we design and implement a framework to reduce Web browsing latency for mobile users with a smart prefetching strategy and caching mechanism. The prefetching strategy leverages the skSLRU model, which predicts and prefetches Web pages based on their contents with consideration of user contexts and the devices' status such as power consuming and cellular data usage. And our caching mechanism mainly consider the resources like CSS and JavaScript files shared among Web pages in a website. Moreover, instead of using RAM, we use ROM, the internal flash memory of devices to store cached resources with proper lifecycle so as to avoid the useful resources to be untimely evicted or expired and thus improve the hit ratio. Our evaluations show that 90% of the homepages and 60% of other pages are fetched before users' visiting, and the page loading time is no more than one second.
由于无线网络连接时断时续,移动Web页面的大小不断增大,移动用户经常会遇到页面加载缓慢的问题。尽管现有的预取和缓存方法被广泛用于减少浏览延迟,但它们可能无法有效地工作,因为大多数Web页面访问是单例的,并且缓存命中率不令人满意。在这项工作中,我们设计并实现了一个框架,通过智能预取策略和缓存机制来减少移动用户的Web浏览延迟。预取策略利用skSLRU模型,该模型根据网页内容预测和预取网页,同时考虑用户上下文和设备状态(如功耗和蜂窝数据使用情况)。我们的缓存机制主要考虑的是一个网站内网页间共享的CSS和JavaScript文件等资源。并且,我们不使用RAM,而是使用设备内部的闪存ROM来存储具有适当生命周期的缓存资源,从而避免有用的资源被过早地驱逐或过期,从而提高命中率。我们的评估表明,90%的首页和60%的其他页面是在用户访问之前获取的,页面加载时间不超过1秒。
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引用次数: 3
Robust network compressive sensing 鲁棒网络压缩感知
Yi-Chao Chen, L. Qiu, Yin Zhang, Guangtao Xue, Zhenxian Hu
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引用次数: 70
The future of mobile computing 移动计算的未来
Jeff Gehlhaar
Jeff Gehlhaar, VP of Technology for Qualcomm Technologies, Inc. will discuss the future of mobile computing which will entail a much more personalized user experience. As the world continues to shift towards a more connected world, people are using their mobile devices in new ways and having higher expectations of what they can do with those devices. This is leading to the next frontier of mobile being much more personalized with mobile devices becoming extensions of the user, understanding where you are, where you've been and what you want to do or act on next. This is also resulting in services and applications that have traditionally been delivered via the cloud, migrating to mobile which present unique challenges and opportunities in mobile. In this talk we will explore the new and exciting technologies that Qualcomm Research is working on to advance the frontier in personalized devices and help solve some of these challenges. Starting with always on sensor processing that make basic predictions about where you are and what actions you are performing, to research in brain inspired computing and embedded cognition, Qualcomm is working to make devices which are always with you, smarter and truly personal. To further this vision of transforming the future of mobile computing, Qualcomm Research has also been working in the area of brain inspired computation and neural networks for a number of years. Early work has focused on biologically inspired approaches, involving spiking neural networks and understanding the complex behaviors of the brain. Recent advances in the industry around deep neural networks have resulted in state-of-the-art performance in machine learning pattern matching tasks. As mobile SOCs continue to gain significant computational power, bringing applications powered by deep learning to mobile devices is becoming possible. We will explore the near term opportunities like object recognition, scene classification, applications for smarter mobile cameras, automotive, and robotics. We will also look at other aspects of brain inspired computing including the potential of a new kind of low power hardware. Join Jeff as he shares his insight on how Qualcomm Research has been spearheading research to make future mobile devices smarter with the ability to "sense" and "see" their environment as humans do in a power efficient manner.
Qualcomm Technologies, Inc.技术副总裁Jeff Gehlhaar将讨论移动计算的未来,这将需要更加个性化的用户体验。随着世界继续向一个更加互联的世界转变,人们正在以新的方式使用他们的移动设备,并对他们可以用这些设备做什么有更高的期望。这将导致下一个移动领域变得更加个性化,移动设备成为用户的延伸,了解你在哪里,你去过哪里,你接下来想做什么或采取什么行动。这也导致传统上通过云交付的服务和应用程序迁移到移动设备,这给移动设备带来了独特的挑战和机遇。在这次演讲中,我们将探讨高通研究公司正在开发的令人兴奋的新技术,以推进个性化设备的前沿,并帮助解决其中的一些挑战。从能对你的位置和行为做出基本预测的传感器处理开始,到大脑启发计算和嵌入式认知的研究,高通正致力于制造永远与你在一起、更智能、真正个性化的设备。为了进一步实现改变移动计算未来的愿景,高通研究公司多年来一直致力于大脑启发计算和神经网络领域的研究。早期的工作集中在受生物学启发的方法上,包括脉冲神经网络和理解大脑的复杂行为。深度神经网络行业的最新进展已经在机器学习模式匹配任务中取得了最先进的性能。随着移动soc继续获得显著的计算能力,将深度学习驱动的应用程序引入移动设备成为可能。我们将探索近期的机会,如物体识别,场景分类,智能移动相机,汽车和机器人的应用。我们还将研究大脑启发计算的其他方面,包括一种新型低功耗硬件的潜力。与Jeff一起分享他的见解,高通研究公司如何率先研究使未来的移动设备更智能,能够像人类一样以节能的方式“感知”和“看到”他们的环境。
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引用次数: 5
Demo: ShadowMaps, the urban phone tracking system 演示:ShadowMaps,城市电话跟踪系统
Andrew T. Irish, Jason T. Isaacs, Daniel Iland, J. Hespanha, E. Belding-Royer, Upamanyu Madhow
Due to frequent non-line-of-sight (NLOS) signal reception, geopositioning using Global Navigation Satellite Systems (GNSS), such as GPS, is unreliable in urban environments, with errors on the order of tens of meters. This poses a major problem for mobile services that benefit from accurate urban localization, such as navigation, geofencing, and hyperlocal advertising applications. Mobile network operators also seek improvements in localization, as government regulators increase handset location accuracy requirements of enhanced 991 service (e911). In our demonstration, we will present the most recent prototype of our urban location improvement technology, called ShadowMaps, which will be shown to accurately track a mobile device in an urban environment, with up to an order of magnitude reduction in GNSS positioning error.
由于频繁的非视距(NLOS)信号接收,使用全球导航卫星系统(GNSS)(如GPS)进行地理定位在城市环境中是不可靠的,误差在几十米左右。这给从精确的城市定位中受益的移动服务(如导航、地理围栏和超本地广告应用)带来了一个主要问题。移动网络运营商也在寻求本地化方面的改进,因为政府监管机构提高了增强991服务(e911)的手机定位精度要求。在我们的演示中,我们将展示我们的城市定位改进技术的最新原型,称为ShadowMaps,它将被证明在城市环境中准确地跟踪移动设备,并将GNSS定位误差降低多达一个数量级。
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引用次数: 7
Enfold: downclocking OFDM in WiFi Enfold: WiFi下行OFDM
Feng Lu, P. Ling, G. Voelker, A. Snoeren
Dynamic voltage and frequency scaling (DVFS) has long been used as a technique to save power in a variety of computing domains but typically not in communications devices. A fundamental limit that prevents decreasing the clock frequency is the Nyquist(-Shannon) sampling theorem, which states that the sampling rate must be twice the signal bandwidth. Recently, researchers have leveraged compressive sensing to demonstrate the possibility of decoding a sparse signal below Nyquist rate. In this work, we dramatically extend the state of the art by showing how to decode non-sparse signals, in particular, OFDM systems at sub-Nyquist rates. We exploit the aliasing that results from under-sampling and observe that there exists well-defined structure in terms of how OFDM signals are "folded up" under aliasing. Based on our observations, we present Enfold, which allows existing WiFi chipsets to decode standards-compliant WiFi frames while operating at 50% and 25% of their rated clock rate. Our design is able to attain greater than 96% and 83% raw packet reception rates for moderate SNR while reducing the clock rate by 2x and 4x, respectively. Moreover, our approach can be easily applied to other communication systems based on OFDM modulation. When evaluated on popular smartphone app traces, Enfold reduces energy consumption by up to 34%.
动态电压和频率缩放(DVFS)长期以来一直被用作各种计算领域的节能技术,但通常不用于通信设备。阻止降低时钟频率的一个基本限制是奈奎斯特(-香农)采样定理,该定理规定采样率必须是信号带宽的两倍。最近,研究人员利用压缩感知来证明解码低于奈奎斯特速率的稀疏信号的可能性。在这项工作中,我们通过展示如何解码非稀疏信号,特别是以亚奈奎斯特速率解码OFDM系统,极大地扩展了目前的技术水平。我们利用了由欠采样引起的混叠,并观察到在混叠下OFDM信号如何“折叠”方面存在定义良好的结构。根据我们的观察,我们提出了Enfold,它允许现有的WiFi芯片组在50%和25%的额定时钟速率下解码符合标准的WiFi帧。我们的设计能够在中等信噪比下获得大于96%和83%的原始数据包接收率,同时分别将时钟速率降低2倍和4倍。此外,我们的方法可以很容易地应用于其他基于OFDM调制的通信系统。通过对流行的智能手机应用程序的评估,Enfold可以减少高达34%的能耗。
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引用次数: 19
Enabling instantaneous feedback with full-duplex backscatter 支持全双工反向散射的瞬时反馈
Vincent Liu, V. Talla, Shyamnath Gollakota
This paper introduces the first design that enables full-duplex communication on battery-free backscatter devices. Specifically, it gives receivers a way to provide low-rate feedback to the transmitter on the same frequency as that of the backscatter transmissions, using neither multiple antennas nor power-consuming cancellation hardware. Our design achieves this goal using only fully-passive analog components that consume near-zero power. We integrate our design with the backscatter network stack and demonstrate that it can minimize energy wastes that occur due to collisions and also correct for errors and changes in channel conditions at a granularity smaller than that of a packet. To show the feasibility of our design, we build a hardware prototype using off-the-shelf analog components. Our evaluation shows that our design cancels the self-interference down to the noise floor, while consuming only 0.25 μW and 0.54 μW of transmit and receive power, respectively.
本文介绍了首个在无电池背散射器件上实现全双工通信的设计。具体来说,它为接收器提供了一种方式,可以在与反向散射传输相同的频率上向发射器提供低速率反馈,而无需使用多个天线或耗能的对消硬件。我们的设计仅使用功耗接近于零的全无源模拟元件实现了这一目标。我们将我们的设计与反向散射网络堆栈集成在一起,并证明它可以最大限度地减少由于碰撞而产生的能量浪费,并且还可以以比数据包更小的粒度纠正信道条件中的错误和变化。为了证明我们设计的可行性,我们使用现成的模拟组件构建了一个硬件原型。我们的评估表明,我们的设计消除了自干扰到噪声底,而发射和接收功率分别仅消耗0.25 μW和0.54 μW。
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引用次数: 81
Poster: detection of transportation mode based on smartphones for reducing distracted driving 海报:基于智能手机的交通方式检测,减少分心驾驶
Xin Gao, Jie Tian, Guiling Wang
Nowadays, distracted driving is becoming a very dangerous epidemic on the roadways. A lot of activities may lead to distracted driving, such as texting, making phone calls, using GPS or road maps, eating, using in-car entertainment systems, etc. As the number of smartphones is rapidly growing year by year, using smartphone is by far the most dangerous and alarming driver distraction. In this paper, we design an app on iPhone for reducing the smartphone-related distracted driving, which can run in the background and can lock the smartphone screen with no passwords required when it detects that the user is driving. After the user finishes driving, the lock will be removed immediately. We also describe a DTM algorithm to detect the transportation mode and give the performance analysis of our system. The results show that our system can save more energy than other related applications.
如今,分心驾驶正在成为道路上一种非常危险的流行病。很多活动都可能导致分心驾驶,比如发短信、打电话、使用GPS或地图、吃东西、使用车内娱乐系统等。随着智能手机的数量逐年快速增长,使用智能手机是迄今为止最危险和最令人担忧的司机分心。在本文中,我们在iPhone上设计了一个应用程序来减少与智能手机相关的分心驾驶,该应用程序可以在后台运行,当检测到用户正在驾驶时,可以不需要密码锁定智能手机屏幕。用户完成驾驶后,锁将立即拆除。我们还描述了一种DTM算法来检测运输模式,并给出了系统的性能分析。结果表明,该系统比其他相关应用更节能。
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引用次数: 2
期刊
Proceedings of the 20th annual international conference on Mobile computing and networking
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