The 20th Annual International Conference on Mobile Computing and Networking, MobiCom'14, Maui, HI, USA, September 7-11, 2014. ACM 【DBLP Link】
【Paper Link】 【Pages】:1-2
【Authors】: Sanjit Biswas
【Abstract】: In 2006, John Bicket and Sanjit Biswas took a leave from their graduate research at MIT to start a networking company called Meraki, which eventually grew to a fast-growing, profitable company acquired by Cisco in 2012 for $1.2 billion. In this talk, Sanjit will recount the history of Meraki, from the Roofnet project at MIT CSAIL, to bootstrapping the business from the sales of their first product, to scaling up to over 500 employees. He will also share some of the lessons learned along the way, and will discuss some similarities between building computer systems as Ph.D. students and building a company.
【Keywords】: computer networking; personal experience; startup
【Paper Link】 【Pages】:3-4
【Authors】: Lakshminarayanan Subramanian ; Sanjit Biswas ; Gaetano Borriello ; Prabal Dutta ; Dina Katabi ; Randy H. Katz
【Abstract】: Mobile computing has deeply influenced the lives of almost every human in the world on a daily basis. In celebration of the 20th anniversary of Mobicom, Mobicom 2014 features an exciting panel on the topic of tackling societal grand challenges using mobile computing. The panel features five excellent researchers who have had a tremendous impact on the field of mobile computing over the years and whose research work has directly addressed pressing societal problems. The panel discussion will feature an in-depth discussion of the grand challenges that we face in society today and the role of mobile computing as a frontier platform for addressing these challenges. The panel will cover both a retrospective and futuristic perspective where the retrospective aspects highlight the diverse contributions of the panelists and the futuristic aspects will feature of a discussion of their individual views of what are the next big societal problems that Mobicom as a community should tackle.
【Keywords】: mobile computing
【Paper Link】 【Pages】:5-16
【Authors】: Yibo Zhu ; Zengbin Zhang ; Zhinus Marzi ; Chris Nelson ; Upamanyu Madhow ; Ben Y. Zhao ; Haitao Zheng
【Abstract】: Mobile network traffic is set to explode in our near future, driven by the growth of bandwidth-hungry media applications. Current capacity solutions, including buying spectrum, WiFi offloading, and LTE picocells, are unlikely to supply the orders-of-magnitude bandwidth increase we need. In this paper, we explore a dramatically different alternative in the form of 60GHz mmwave picocells with highly directional links. While industry is investigating other mmwave bands (e.g. 28GHz to avoid oxygen absorption), we prefer the unlicensed 60GHz band with highly directional, short-range links (~100m). 60GHz links truly reap the spatial reuse benefits of small cells while delivering high per-user data rates and leveraging efforts on indoor 60GHz PHY technology and standards. Using extensive measurements on off-the-shelf 60GHz radios and system-level simulations, we explore the feasibility of 60GHz picocells by characterizing range, attenuation due to reflections, sensitivity to movement and blockage, and interference in typical urban environments. Our results dispel some common myths, and show that there are no fundamental physical barriers to high-capacity 60GHz outdoor picocells. We conclude by identifying open challenges and associated research opportunities.
【Keywords】: 60ghz wireless; picocells; wireless beamforming
【Paper Link】 【Pages】:17-28
【Authors】: Tan Zhang ; Ning Leng ; Suman Banerjee
【Abstract】: 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.
【Keywords】: channel quality; localization; propagation model; spectrum database; tv whitespaces; vehicular sensing
【Paper Link】 【Pages】:29-40
【Authors】: Narendra Anand ; Ryan E. Guerra ; Edward W. Knightly
【Abstract】: While the UHF band exhibits superior propagation characteristics compared to other frequency bands used for broadband communications, limited spectral availability in time and space necessitates high spectral efficiency techniques such as Multi-user MIMO (MU-MIMO). In this paper we design and implement the first open MU-MIMO Software-Defined Radio (SDR) platform that operates on an order of magnitude frequency range, from 300 MHz to 5.8 GHz. We perform a comprehensive set of over-the-air experiments to evaluate the potential of UHF-band MU-MIMO in comparison to 2.4 and 5.8 GHz WiFi bands encompassing a range of operating environments. We evaluate MU-MIMO performance in both outdoor, indoor, line-of-sight (LOS), and non-line-of-sight (NLOS) environments, and demonstrate that while the temporal correlation of the measured UHF environment is increased, it does not come at the cost of increased spatial correlation as measured by the Demmel condition number, thus proving highly attractive for MU-MIMO. This evaluation demonstrates the effectiveness of MU-MIMO transmission techniques in UHF bands for high spectral efficiency and low-overhead wireless access.
【Keywords】: beamforming; channel correlation; channel measurement; channel state information; demmel condition number; multi-user mimo; uhf
【Paper Link】 【Pages】:41-52
【Authors】: Anran Wang ; Shuai Ma ; Chunming Hu ; Jinpeng Huai ; Chunyi Peng ; Guobin Shen
【Abstract】: 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.
【Keywords】: dynamic barcodes; reliability; smartphones; transmission
【Paper Link】 【Pages】:53-54
【Authors】: Jeff Gehlhaar
【Abstract】: 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.
【Keywords】: artifical intelligence; brain inspired computing; embedded cognition; machine learning; mobile; sensor future
【Paper Link】 【Pages】:55-66
【Authors】: Karthikeyan Sundaresan ; Mohammad Ali Khojastepour ; Eugene Chai ; Sampath Rangarajan
【Abstract】: Enabling wireless full-duplex (from an AP) with multiple half-duplex (HD) clients is key to widespread adoption of full-duplex (FD) in commercial networks. However, enabling FD in such networks is fundamentally challenged by a new form of uplink-downlink interference (UDI), arising between HD clients operating simultaneously in the uplink and downlink directions. In this context, we first show that spatial interference alignment (IA) between clients is an effective and scalable technique to address UDI and hence enable FD in these networks, especially in the presence of MIMO. We then present our solution and system FDoS: Full-Duplex without Stringsthat incorporates this notion. We build the theory of applying spatial IA to full-duplex networks in general and present elegant, implementation-friendly constructions for generating IA solutions, by leveraging the structure of interference specific to these networks. In the process, FDoS shows that only four HD clients are sufficient to eliminate UDI through IA and enable 2N streams at an N transceiver AP. FDoS also includes an efficient MAC design at the AP to handle clients with heterogeneous antenna capabilities, maximize the throughput of the enabled streams in the FD session as well as reduce the overhead incurred in FDoS by half by facilitating a distributed implementation. A prototype of FDoS on WARP radios showcases its ability to address UDI effectively, and hence enable 2N streams (for N=2,4) in varied settings with just four HD clients, and sustain rate gains of 1.75-2x over HD MU-MIMO systems.
【Keywords】: full-duplex; half-duplex clients; spatial interference alignment; uplink-downlink interference
【Paper Link】 【Pages】:67-78
【Authors】: Vincent Liu ; Vamsi Talla ; Shyamnath Gollakota
【Abstract】: 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.
【Keywords】: backscatter; full-duplex wireless; wireless
【Paper Link】 【Pages】:79-90
【Authors】: Wenjun Hu ; Jingshu Mao ; Zihui Huang ; Yiqing Xue ; Junfeng She ; Kaigui Bian ; Guobin Shen
【Abstract】: Existing code designs for display-camera based visual communication all have an all-or-nothing behavior, i.e., they assume the entire code must be decoded. However, diverse operational conditions due to device hardware diversity (in camera resolution and frame rate) and distance range motivate more scalable designs. In this paper, we borrow the notion of hierarchical modulation from traditional RF communication, and design Strata, a layered coding scheme for visual communication. Strata can support a range of frame capture resolutions and rates, and deliver information rates correspondingly. Strata embeds information at multiple granularity into the same code area spatially or the same frame interval temporally. It ensures all layers are decodable independently, by controlling the amount of interference between adjacent layers. Further, our design is recursive and extends readily to generate more layers. Compared with existing codes, it significantly extends the operational range, though at the expense of less capacity than a single-layer code.
【Keywords】: display-camera links; layered coding; scalable visual communication
【Paper Link】 【Pages】:91-102
【Authors】: Lan Zhang ; Xiang-Yang Li ; Wenchao Huang ; Kebin Liu ; Shuwei Zong ; Xuesi Jian ; Puchun Feng ; Taeho Jung ; Yunhao Liu
【Abstract】: In this work, we explore a new networking mechanism with smart glasses, through which users can express their interest and connect to a target simply by a gaze. Doing this, we attempt to let wearable devices understand human attention and intention, and pair devices carried by users according to such attention and intention. To achieve this ambitious goal, we propose a proof-of-concept system iGaze, a visual attention driven networking suite: an iGaze glass (hardware), and a networking protocol VAN (software). Our glass, iGaze glass, is a low-cost head-mounted glass with a camera, orientation sensors, microphone and speakers, which are embedded with our software for visual attention capture and networking. A visual attention driven networking protocol (VAN) is carefully designed and implemented. In VAN, we design an energy efficient and highly accurate visual attention determination scheme using single camera to capture user's communication interest and a double-matching scheme based on visual direction detection and Doppler effect of acoustic signal to lock the target devices. Using our system, we conduct a series of trials for various application scenarios to demonstrate the effectiveness of our system.
【Keywords】: attention driven networking; device paring; gaze tracking; smart glasses
【Paper Link】 【Pages】:103-114
【Authors】: Farnoosh Moshir ; Suresh Singh
【Abstract】: There are numerous scenarios where embedding static information into objects would prove to be very useful. For example, by embedding navigation information into the road surface we could enable driverless cars, similarly embedding information into major infrastructure such as building walls would enable easier classification of debris, and so forth. The key requirement is that the embedded information should survive as long as the infrastructure itself. We discuss the concept of wireless barcodes that allow us to achieve exactly this goal of tagging infrastructure. The barcodes are designed to be read at terahertz frequencies that allows good packing of information (bits/m). We use a TDoA (Time Difference of Arrival) technique to read the barcodes which provides robustness to wear and tear of the surface. This paper reports on the results of an experimental study that examines the challenges in building such barcodes and demonstrates the idea by constructing such a barcode.
【Keywords】: barcodes; propagation; terahertz
【Paper Link】 【Pages】:115-126
【Authors】: Swati Rallapalli ; Aishwarya Ganesan ; Krishna Chintalapudi ; Venkata N. Padmanabhan ; Lili Qiu
【Abstract】: We consider the problem of tracking physical browsing by users in indoor spaces such as retail stores. Analogous to online browsing, where users choose to go to certain webpages, dwell on a subset of pages of interest to them, and click on links of interest while ignoring others, we can draw parallels in the physical setting, where a user might walk purposefully to a section of interest, dwell there for a while, gaze at specific items, and reach out for the ones that they wish to examine more closely. As our first contribution, we design techniques to track each of these elements of physical browsing using a combination of a first-person vision enabled by smart glasses, and inertial sensing using both the glasses and a smartphone. We address key challenges, including energy efficiency by using the less expensive inertial sensors to trigger the more expensive vision processing. Second, during gazing, we present a method for identifying the item(s) within view that the user is likely to focus on based on measuring the orientation of the user's head. Finally, unlike in the online context, where every webpage is just a click away, proximity is important in the physical browsing setting. To enable the tracking of nearby items, even if outside the field of view, we use data gathered from smart-glasses-enabled users to infer the product layout using a novel technique called AutoLayout. Further, we show how such inferences made from a small population of smart-glasses-enabled users could aid in tracking the physical browsing by the many smartphone-only users.
【Keywords】: localization; physical analytics; retail spaces; smart glasses; wearables; wifi
【Paper Link】 【Pages】:127-128
【Authors】: Leonard Kleinrock
【Abstract】: A number of interesting problems that I have addressed over the years which yielded surprisingly simple results will be presented. Many of these had intuitively pleasing interpretations or especially simple proofs and/or insights.
【Keywords】: broadband networks; intelligent software agents; internet; local area networks; packet radio networks; packet switching networks; performance evaluation
【Paper Link】 【Pages】:129-140
【Authors】: Feng Lu ; Patrick Ling ; Geoffrey M. Voelker ; Alex C. Snoeren
【Abstract】: 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%.
【Keywords】: downclocking; dvfs; energy efficiency; ofdm; wifi
【Paper Link】 【Pages】:141-152
【Authors】: Hang Yu ; Oscar Bejarano ; Lin Zhong
【Abstract】: In an 802.11ac-based MU-MIMO network comprised of multiple cells1, inter-cell interference allows only a single AP to serve its clients at the same time, significantly limiting the network capacity. In this work, we overcome this limitation by letting the APs and clients in interfering cells coordinately cancel the inter-cell interference using their antennas for beamforming. To achieve such coordinated interference cancellation in a practical way, we propose a novel two-step optimization. First, without requiring any channel knowledge, each AP and client optimizes the use of its antennas for either data communication or inter-cell interference cancellation, in order to maximize the total number of deliverable streams in the MU-MIMO network. Second, with only partial channel knowledge, each AP and client optimizes their beamforming weights after the optimal antenna usage has been identified in the first step. Our solution, CoaCa, integrates this two-step optimization into 802.11ac with small modifications and negligible overhead, allowing each AP and client to locally perform the two-step optimization. Our experimental evaluation indicates that for a MU-MIMO network with two cells, by cancelling the inter-cell interference CoaCa can convert the majority of the expected number of streams increase (50%-67%) into network capacity improvement (41%-52%).
【Keywords】: 802.11ac; coaca; inter-cell interference; multi-user mimo
【Paper Link】 【Pages】:153-164
【Authors】: Jon Gjengset ; Jie Xiong ; Graeme McPhillips ; Kyle Jamieson
【Abstract】: Signal processing on antenna arrays has received much recent attention in the mobile and wireless networking research communities, with array signal processing approaches addressing the problems of human movement detection, indoor mobile device localization, and wireless network security. However, there are two important challenges inherent in the design of these systems that must be overcome if they are to be of practical use on commodity hardware. First, phase differences between the radio oscillators behind each antenna can make readings unusable, and so must be corrected in order for most techniques to yield high-fidelity results. Second, while the number of antennas on commodity access points is usually limited, most array processing increases in fidelity with more antennas. These issues work in synergistic opposition to array processing: without phase offset correction, no phase-difference array processing is possible, and with fewer antennas, automatic correction of these phase offsets becomes even more challenging. We present Phaser, a system that solves these intertwined problems to make phased array signal processing truly practical on the many WiFi access points deployed in the real world. Our experimental results on three- and five-antenna 802.11-based hardware show that 802.11 NICs can be calibrated and synchronized to a 20° median phase error, enabling inexpensive deployment of numerous phase-difference based spectral analysis techniques previously only available on costly, special-purpose hardware.
【Keywords】: angle-of-arrival; location tracking; nics synchronization; phase calibration; phased-array; signal processing
【Paper Link】 【Pages】:165-176
【Authors】: Wenjie Zhou ; Tarun Bansal ; Prasun Sinha ; Kannan Srinivasan
【Abstract】: Today's Enterprise Wireless LANs are comprised of densely deployed access points. This paper proposes BBN, an interference nulling scheme that leverages the high density of access points to enable multiple mobile devices to transmit simultaneously to multiple access points (APs), all within a single collision domain. BBN also leverages the capability of the APs to communicate with each other on the wired backbone to migrate most of the decoding complexity to the APs, while keeping the design at the mobile clients simple. Finally, we leverage the static nature of the access points to make BBN more practical in networks where the mobility of clients inhibit the use of traditional interference alignment schemes. We implement a prototype of BBN on USRP testbed showing its feasibility. The experiment results show that BBN provides a throughput gain of 1.48X over omniscient TDMA. Results from our trace-driven simulations show that BBN obtains a throughput of up to 5.6X over omniscient TDMA.
【Keywords】: blind beamforming and nulling; enterprise networks
【Paper Link】 【Pages】:177-188
【Authors】: Sanae Rosen ; Haokun Luo ; Qi Alfred Chen ; Zhuoqing Morley Mao ; Jie Hui ; Aaron Drake ; Kevin Lau
【Abstract】: To conserve power while ensuring good performance on resource-constrained mobile devices, devices transition between different Radio Resource Control (RRC) states in response to network traffic and according to parameters specific to network operators. As RRC states significantly affect application power consumption and performance, it is important to understand how RRC state timers interact with network traffic patterns. In this paper, we show that the impact of RRC states on performance is significantly more complex and diverse than found in previous work. To do so, we introduce an open-source tool that allows the impact of RRC states on network and application performance to be measured in a robust and accurate manner on unmodified user devices, and deploy the tool in 23 countries around the world to test a broad range of cellular network technologies. We detect previously unknown performance problems which increase network latencies by up to several seconds and for LTE, can increase packet losses by an order of magnitude. Through an in-depth cross-layer analysis of several carriers, we examine the lower-layer causes of these problems. We determine that the highly complex state transitions of certain carriers, and in particular poor interactions between state demotions and network traffic, can lead to substantial, unexpected latencies.
【Keywords】: 3g; 4g lte; application qoe; cellular network performance; rrc state machine; smartphones
【Paper Link】 【Pages】:189-200
【Authors】: Rajesh Mahindra ; Harish Viswanathan ; Karthik Sundaresan ; Mustafa Y. Arslan ; Sampath Rangarajan
【Abstract】: Mobile operators are leveraging WiFi to relieve the pressure posed on their networks by the surging bandwidth demand of applications. However, operators often lack intelligent mechanisms to control the way users access their WiFi networks. This lack of sophisticated control creates poor network utilization, which in turn degrades the quality of experience (QoE). To meet user traffic demands, it is evident that operators need solutions that optimally balance user traffic across cellular and WiFi networks. Motivated by the lack of practical solutions in this space, we design and implement ATOM - an end-to-end system for adaptive traffic offloading for WiFi-LTE deployments. ATOM has two novel components: (i) A network interface selection algorithm that maps user traffic across WiFi and LTE to optimize user QoE and (ii) an interface switching service that seamlessly re-directs ongoing user sessions in a cost-effective and standards-compatible manner. Our evaluations on a real LTE-WiFi testbed using YouTube traffic reveals that ATOM reduces video stalls by 3-4 times compared to naive solutions.
【Keywords】: cellular networks; traffic management; wifi offload
【Paper Link】 【Pages】:201-212
【Authors】: Desheng Zhang ; Jun Huang ; Ye Li ; Fan Zhang ; Cheng-Zhong Xu ; Tian He
【Abstract】: Expanding our knowledge about human mobility is essential for building efficient wireless protocols and mobile applications. Previous human mobility studies have typically been built upon empirical single-source data (e.g., cellphone or transit data), which inevitably introduces a bias against residents not contributing this type of data, e.g., call detail records cannot be obtained from the residents without cellphone activities, and transit data cannot cover the residents who walk or ride private vehicles. To address this issue, we propose and implement a novel architecture mPat to explore human mobility using multi-source data. A reference implementation of mPat was developed at an unprecedented scale upon the urban infrastructures of Shenzhen, China. The novelty and uniqueness of mPat lie in its three layers: (i) a data feed layer consisting of real-time data feeds from 24 thousand vehicles, 16 million smart cards and 10 million cellphones; (ii) a mobility abstraction layer exploring the correlation and divergence among the multi-source data to analyze and infer human mobility; and (iii) an application layer to improve urban efficiency based on the human mobility findings of the study. The evaluation shows that mPat achieves a 75% inference accuracy, and that its real-world application reduces passenger travel time by 36%.
【Keywords】: cellphone networks; mobility pattern; urban transit networks
【Paper Link】 【Pages】:213-224
【Authors】: Athula Balachandran ; Vaneet Aggarwal ; Emir Halepovic ; Jeffrey Pang ; Srinivasan Seshan ; Shobha Venkataraman ; He Yan
【Abstract】: Recent studies have shown that web browsing is one of the most prominent cellular applications. It is therefore important for cellular network operators to understand how radio network characteristics (such as signal strength, handovers, load, etc.) influence users' web browsing Quality-of-Experience (web QoE). Understanding the relationship between web QoE and network characteristics is a pre-requisite for cellular network operators to detect when and where degraded network conditions actually impact web QoE. Unfortunately, cellular network operators do not have access to detailed server-side or client-side logs to directly measure web QoE metrics, such as abandonment rate and session length. In this paper, we first devise a machine-learning-based mechanism to infer web QoE metrics from network traces accurately. We then present a large-scale study characterizing the impact of network characteristics on web QoE using a month-long anonymized dataset collected from a major cellular network provider. Our results show that improving signal-to-noise ratio, decreasing load and reducing handovers can improve user experience. We find that web QoE is very sensitive to inter-radio-access-technology (IRAT) handovers. We further find that higher radio data link rate does not necessarily lead to better web QoE. Since many network characteristics are interrelated, we also use machine learning to accurately model the influence of radio network characteristics on user experience metrics. This model can be used by cellular network operators to prioritize the improvement of network factors that most influence web QoE.
【Keywords】: cellular network; performance; quality of experience (qoe); web browsing
【Paper Link】 【Pages】:225-236
【Authors】: Song Fang ; Yao Liu ; Wenbo Shen ; Haojin Zhu
【Abstract】: In wireless networks, location distinction aims to detect location changes or facilitate authentication of wireless users. To achieve location distinction, recent research has been focused on investigating the spatial uncorrelation property of wireless channels. Specifically, the differences of wireless channel characteristics are used to distinguish locations or identify location changes. However, we discover a new attack against all existing location distinction approaches that are built on the spatial uncorrelation property of wireless channels. In such an attack, the adversary can easily hide her location changes or impersonate movements by injecting fake wireless channel characteristics into a target receiver. Experimental results on our USRP-based prototype show that the discovered attack can craft any desired channel characteristic with a successful probability of 95.0% to defeat spatial uncorrelation based location distinction schemes. To defend against this attack, we propose a detection technique that utilizes an auxiliary receiver or antenna to identify these fake channel characteristics. Experiments demonstrate that our novel detection method achieves a detection rate higher than 91.2% while maintaining a very low false alarm rate.
【Keywords】: channel impulse response; mimo; multipath; security
【Paper Link】 【Pages】:237-248
【Authors】: Lei Yang ; Yekui Chen ; Xiang-Yang Li ; Chaowei Xiao ; Mo Li ; Yunhao Liu
【Abstract】: In many applications, we have to identify an object and then locate the object to within high precision (centimeter- or millimeter-level). Legacy systems that can provide such accuracy are either expensive or suffering from performance degradation resulting from various impacts, e.g., occlusion for computer vision based approaches. In this work, we present an RFID-based system, Tagoram, for object localization and tracking using COTS RFID tags and readers. Tracking mobile RFID tags in real time has been a daunting task, especially challenging for achieving high precision. Our system achieves these three goals by leveraging the phase value of the backscattered signal, provided by the COTS RFID readers, to estimate the location of the object. In Tagoram, we exploit the tag's mobility to build a virtual antenna array by using readings from a few physical antennas over a time window. To illustrate the basic idea of our system, we firstly focus on a simple scenario where the tag is moving along a fixed track known to the system. We propose Differential Augmented Hologram (DAH) which will facilitate the instant tracking of the mobile RFID tag to a high precision. We then devise a comprehensive solution to accurately recover the tag's moving trajectories and its locations, relaxing the assumption of knowing tag's track function in advance. We have implemented the Tagoram system using COTS RFID tags and readers. The system has been tested extensively in the lab environment and used for more than a year in real airline applications. For lab environment, we can track the mobile tags in real time with a millimeter accuracy to a median of 5mm and 7.29mm using linear and circular track respectively. In our year- long large scale baggage sortation systems deployed in two airports, our results from real deployments show that Tagoram can achieve a centimeter-level accuracy to a median of 6.35cm in these real deployments.
【Keywords】: dah; localization; rfid; tagoram; tracking
【Paper Link】 【Pages】:249-260
【Authors】: Ruipeng Gao ; Mingmin Zhao ; Tao Ye ; Fan Ye ; Yizhou Wang ; Kaigui Bian ; Tao Wang ; Xiaoming Li
【Abstract】: The lack of floor plans is a critical reason behind the current sporadic availability of indoor localization service. Service providers have to go through effort-intensive and time-consuming business negotiations with building operators, or hire dedicated personnel to gather such data. In this paper, we propose Jigsaw, a floor plan reconstruction system that leverages crowdsensed data from mobile users. It extracts the position, size and orientation information of individual landmark objects from images taken by users. It also obtains the spatial relation between adjacent landmark objects from inertial sensor data, then computes the coordinates and orientations of these objects on an initial floor plan. By combining user mobility traces and locations where images are taken, it produces complete floor plans with hallway connectivity, room sizes and shapes. Our experiments on 3 stories of 2 large shopping malls show that the 90-percentile errors of positions and orientations of landmark objects are about 1~2m and 5~9°, while the hallway connectivity is 100% correct.
【Keywords】: indoor floor plan reconstruction; mobile crowdsensing
【Paper Link】 【Pages】:261-262
【Authors】: Fadel Adib ; Zachary Kabelac ; Hongzi Mao ; Dina Katabi ; Robert C. Miller
【Abstract】: This demo presents Vital-Radio, a wireless sensing technology that monitors breathing remotely, without requiring any body contact. Vital-Radio operates by transmitting a low-power wireless signal and monitoring its reflections off the human body. It uses these reflections to track motion associated with breathing, i.e., the chest movements caused by inhaling and exhaling. The demo will enable any person to sit in front of the device and check that it tracks their inhale and exhale process. The person may hold his/her breath and check that the device detects the breath holding event in real-time.
【Keywords】: breathing; seeing through walls; smart homes; vital signs; wireless
【Paper Link】 【Pages】:263-266
【Authors】: Andrius Aucinas ; Jon Crowcroft
【Abstract】: This demo presents how phone functionality can be offloaded from a smartphone over wireless link to a PhoneLet by sharing one SIM card across multiple devices. This can lead to significant cost and network load reductions by decreasing the number of simultaneously connected mobile clients. Furthermore, it can save energy for the mobile user when connected to a powered PhoneLet by offloading phone functionality. It absorbs the energy cost of online presence and inefficient mobile applications' communication patterns, instead providing connectivity for the user over a WiFi link.
【Keywords】: cellular; energy; mobile; networks; sim; subscriber management
【Paper Link】 【Pages】:267-270
【Authors】: Fehmi Ben Abdesslem ; Anders Lindgren
【Abstract】: Information-Centric Networking (ICN) is an alternative architecture for computer networks, where the communication is focused on the data being transferred instead of the communicating hosts. This paper describes a demo of an experience sharing application for mobile phones built on an ICN platform designed for devices with intermittent connectivity. In particular, we detail how this application will be showcased in an indoor exhibition where experience is shared with media content that is geo-tagged using Bluetooth beacons and spread opportunistically to other users.
【Keywords】: information-centring networking; opportunistic networks
【Paper Link】 【Pages】:271-274
【Authors】: Aishwarya Ganesan ; Swati Rallapalli ; Krishna Chintalapudi ; Venkata N. Padmanabhan ; Lili Qiu
【Abstract】:
【Keywords】: physical analytics; smart glasses; user browsing; wearables
【Paper Link】 【Pages】:275-278
【Authors】: Ryan E. Guerra ; Narendra Anand ; Edward W. Knightly
【Abstract】: We present a real-time software-defined radio (SDR) platform for prototyping and measuring the performance of broadband UHF radio networks operating over long distances with point-to-multipoint (PTMP) non-line-of-sight (NLOS) networks. Enabled by the Wideband UHF Radio Card (WURC), a custom high-power and frequency-flexible radio transceiver daughter-card for FPGA-based digital basebands, the 802.11 DCF-like MAC and PHY implementation is completely open source. We demonstrate a long-range PTMP NLOS network bonding several of the white space television channels available in Maui, Hawaii. Off-the-shelf client devices can use this network via 802.11a/g links implemented with the same SDR framework. The multi-carrier channel estimates and real-time MAC statistics of connected nodes in UHF and 2.4 GHz are recorded and displayed in real-time, demonstrating an unprecedented amount of flexibility in unlicensed frequency bands, enabling real-time TV-band cognitive networks and small-cell research deployments. A demonstration video is available at the following link: http://youtu.be/dTOJHRICklQ
【Keywords】: channel measurement; last-mile; mac; small cell; software-defined radio; uhf; wifi hotspot
【Paper Link】 【Pages】:279-282
【Authors】: Christopher Hunter ; Patrick Murphy ; Erik Welsh
【Abstract】: We present a demonstration of the real-time capture and analysis of multi-user MIMO (MU-MIMO) channel state information from commercial Wi-Fi devices. Our system is built with an array of WARP v3 nodes running the Mango Communications 802.11 Reference Design, an open-source, real-time FPGA implementation of the 802.11a/g MAC and PHY. One WARP v3 node acts as an 802.11 access point (AP), which serves Internet access to client devices. The other nodes implement an array of multi-antenna 802.11 monitors. Every monitor node simultaneously receives packets transmitted by the Wi-Fi clients associated with the AP. The nodes extract MAC headers and channel estimates from each packet and offload these to a PC for analysis. All MAC, PHY, and channel analysis processes run in real time.
【Keywords】: dcf mac; ieee 802.11; mu-mimo; ofdm phy
【Paper Link】 【Pages】:283-286
【Authors】: Andrew Irish ; Jason T. Isaacs ; Daniel Iland ; João P. Hespanha ; Elizabeth M. Belding ; Upamanyu Madhow
【Abstract】: 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.
【Keywords】: 3d mapping; crowdsourcing; gnss; gps; localization improvement; system demonstration
【Paper Link】 【Pages】:287-290
【Authors】: Stefan Joerer ; Bastian Bloessl ; Matthaeus Huber ; Abbas Jamalipour ; Falko Dressler
【Abstract】: Performance evaluation of communication protocols is usually carried out using typical network metrics as delay, jitter, or goodput. However, recent studies in the context of Inter-Vehicle Communication (IVC) have shown that using these metrics is not sufficient for evaluating vehicular safety applications. To highlight the importance of safety metrics and their applicability, we extended our existing simulation framework Veins to visualize these metrics live while the road traffic and network simulation are running in parallel. In particular, we demonstrate the impact of communication on intersection assistance applications. To simulate different intersection approaches, we implemented a simulation model that resembles different kinds of driver behavior and enables crashes at intersections. The resulting situations are displayed in the road traffic simulator and give the visitor insights on the current state of endangered vehicles. Furthermore, an autonomous controller has been implemented which tries to avoid accidents and hence shows the real-world impact, i.e., accidents can be avoided using advanced beaconing techniques. To increase interactivity of the demo, visitors will have the possibility to interact with and take control over endangered vehicles.
【Keywords】: inter-vehicle communication; simulation model; vanet; vehicle safety
【Paper Link】 【Pages】:291-294
【Authors】: Markku Jokinen ; Marko Mäkeläinen ; Tuomo Hänninen
【Abstract】: A co-primary spectrum sharing trial is presented in this paper. It is presenting a flexible way to share resources between multiple operators in order to increase spectral efficiency. In this trial the differences in traffic patterns of the mobile network operators are exploited to ease up the peak traffic demands of particular operator. This shared recourse is also usable for inter-operator D2D communication, when two users of different operators want to communicate and operators need to negotiate resource allocation for this communication link. We will also introduce Wireless Open Access Research Platform as our choice for the implementation of this trial.
【Keywords】: inter-operator; sharing; warp
【Paper Link】 【Pages】:295-298
【Authors】: Stratos Keranidis ; Kostas Chounos ; Thanasis Korakis ; Iordanis Koutsopoulos ; Leandros Tassiulas
【Abstract】: In this work, we present the AGILE Spectrum Adaptation system that is able to dynamically tune the channel central frequency and bandwidth of wireless links in an adaptive to the interference and traffic conditions way. The developed system is able to detect under-utilised spectrum fragments and optimally adjust the occupied spectrum. Through the online execution of 3 specifically designed experimental scenarios, we demonstrate the ability to implement distributed spectrum adaptation in commercial WLAN deployments, along with the obtained performance benefits.
【Keywords】: 802.11; agile; cognitive; distributed; dynamic spectrum adaptation
【Paper Link】 【Pages】:299-302
【Authors】: Ye-Sheng Kuo ; Pat Pannuto ; Prabal Dutta
【Abstract】: We explore the indoor positioning problem with unmodified smartphones and slightly-modified commercial LED luminaires. The luminaires - modified to allow rapid, on-off keying - transmit their identifiers and/or locations encoded in human-imperceptible optical pulses. A camera-equipped smartphone, using just a single image frame capture, can detect the presence of the luminaires in the image, decode their transmitted identifiers and/or locations, and determine the smartphone's location and orientation relative to the luminaires. Continuous image capture and processing enables continuous position updates. The key insights underlying this work are (i) the driver circuits of emerging LED lighting systems can be easily modified to transmit data through on-off keying; (ii) the rolling shutter effect of CMOS imagers can be leveraged to receive many bits of data encoded in the optical transmissions with just a single frame capture, (iii) a camera is intrinsically an angle-of-arrival sensor, so the projection of multiple nearby light sources with known positions onto a camera's image plane can be framed as an instance of a sufficiently-constrained angle-of-arrival localization problem, and (iv) this problem can be solved with optimization techniques.
【Keywords】: angle-of-arrival; image processing; indoor localization; mobile phones
【Paper Link】 【Pages】:303-304
【Authors】: Wei Liu ; Eli De Poorter ; Pieter Becue ; Bart Jooris ; Vincent Sercu ; Ingrid Moerman ; Jeroen Vanhaverbeke ; Carl Lylon ; John Gesquiere
【Abstract】: In a modern conference room, various of video and audio devices are provided to ensure efficient communications. This is commonly referred to as a conferencing system. Compared to wired conferencing systems, wireless systems require less deployment effort, but may become unreliable when the selected radio spectrum is highly occupied. This demo focuses on improving the quality of service of a commercial wireless conferencing system using dynamic channel selection based on real-time spectrum sensing. The proposed solution is verified in a large-scale wireless testbed, and the result shows that the link of the conferencing system is indeed more robust against interference when cognitive solution is applied.
【Keywords】: cognitive radio; wireless conferencing system
【Paper Link】 【Pages】:305-308
【Authors】: Navid Nikaein ; Raymond Knopp ; Florian Kaltenberger ; Lionel Gauthier ; Christian Bonnet ; Dominique Nussbaum ; Riadh Ghaddab
【Abstract】: LTE 4G cellular networks are gradually being adopted by all major operators in the world and are expected to rule the cellular landscape at least for the current decade. They will also form the starting point for further progress beyond the current generation of mobile cellular networks to chalk a path towards fifth generation mobile networks. The lack of open cellular ecosystem has limited applied research in this field within the boundaries of vendor and operator R&D groups. Furthermore, several new approaches and technologies are being considered as potential elements making up such a future mobile network, including cloudification of radio network, radio network programability and APIs following SDN principles, native support of machine-type communication, and massive MIMO. Research on these technologies requires realistic and flexible experimentation platforms that offer a wide range of experimentation modes from real-world experimentation to controlled and scalable evaluations while at the same time retaining backward compatibility with current generation systems. In this work, we present OpenAirInterface (OAI) as a suitably flexible platform towards open LTE ecosystem and playground [1]. We will demonstrate an example of the use of OAI to deploy a low-cost open LTE network using commodity hardware with standard LTE-compatible devices. We also show the reconfigurability features of the platform.
【Keywords】: lte; open cellular ecosystem; openairinterface
【Paper Link】 【Pages】:309-312
【Authors】: George Nychis ; Bruce DeBruhl ; Haiyun Tang
【Abstract】: Over the past decade, white space networking has garnered significant effort and attention from media, industry, regulators, and academics world-wide. Together, these entities have helped push white space in to a unique position of potentially changing how we access the spectrum (more efficiently) forever. Now, building white space networks with full-featured and fully certified equipment is critical in moving forward and retaining the spectrum and position that we have put ourselves in. In our demonstration, we will exhibit a fully embedded and FCC-certified white space networking platform that is available and capable of building out TV white space networks. Additionally, we provide an interactive display with data taken from our commercial deployments that further show its capabilities of supporting various applications. Using the many available channels at the conference location, we will demonstrate some of these capabilities (e.g., ability to penetrate in-door environments), as well as future capabilities (e.g., novel functionality built on the platform). With an open-API (across all layers), the platform is conducive to studying current capabilities and novel research.
【Keywords】: tv white space; white space; white space database; wireless networking
【Paper Link】 【Pages】:313-316
【Authors】: Yongtae Park ; JeongGil Ko ; Hyogon Kim
【Abstract】: In this demo, we showcase the first software defined radio (SDR) implementation that runs on today's smartphones. Using the SDR, the smartphones are shown to talk to real IEEE 802.15.4 devices such as sensor motes or Phillips Hue (TM) lightbulbs that otherwise they cannot natively communicate with. Furthermore, we make the SDR available as downloadable software ("app") on Google app store, so that anyone may freely download, use, and purge on his or her smartphone, independently of OS upgrades. Detaching SDR from OS allows almost immediate deployment of wireless rotocols, and only on the phones that do need them. By enabling smartphones to speak non-native protocols in this manner, smartphone vendors will be able to support a wide range of wireless protocols without investing separate hardware and real estate in their devices. A promising application area for this concept could be Internet of Things (IoT), where protocols are diverse, typically low-speed, and not well supported by today's smartphones. Therefore, we believe that the smartphones with SDR will become a strong enabler or facilitator of many interesting applications in the IoT environment. We also believe that the concept of wireless protocol as a smartphone app will accelerate wireless protocol design-test-deployment cycle, catalyzing wireless protocol evolutions on smartphones.
【Keywords】: app; smartphone; software defined radio
【Paper Link】 【Pages】:317-320
【Authors】: Hsin-Mu Tsai ; Hao-Min Lin ; Hui-Yu Lee
【Abstract】: Camera communication (CamCom) is a form of visible light communication (VLC) that makes use of a camera as the receiver. One very important advantage of CamCom is that the acquired images during the receiving process provide a means to visually associate the physical object with the transmitted information, since the receiver has the knowledge of which pixels in the images are transmitting. Figure 1 shows a simple example. A user points her smartphone camera at multiple lights, touches the screen to select one, and uses the virtual switch that appears on the screen to adjust the lighting level. In this scenario, the lights simply periodically transmit simple identifiers, such as IP addresses, to the smartphone. The system is able to directly associate what the user sees (the image pixels corresponding to the light selected by the user) to the transmitted information (the identifier of the light). An out-of-band channel, such as WiFi, can then be used to send the actual command to the selected light to adjust the setting. Compared to the conventional approach of identifying a particular set of visual features unique to the object with computer vision techniques, this approach is simpler, more intuitive, and more accurate.
【Keywords】: camera communications; frequency shift keying; rolling shutter; visible light communications
【Paper Link】 【Pages】:321-324
【Authors】: Anran Wang ; Shuai Ma ; Chunming Hu ; Jinpeng Huai ; Chunyi Peng ; Guobin Shen
【Abstract】: Visible light communication (VLC) over screen-camera links emerges as a novel form of near-field communication, and it offers a user-friendly, infrastructure-less and secure communication, which is highly competitive for one-time file transfer [1 - 4]. However, the limitations of smart devices and the uncertainty of user behaviors seriously impair the transmission reliability and hinder its applicability. Worse still, existing approaches [1, 2, 4]mostly focus on improving the transmission speed and ignore the transmission reliability. Hence, RDCode is proposed to boost the throughput over screen-camera links, by making use of a novel barcode design and several effective techniques to enhance the transmission reliability. In this demo, we show that our RDCode prototype system addresses many practical challenges. A short video on our prototype system is accessible from http://mashuai.buaa.edu.cn/demo/RDCode.mp4.
【Keywords】: dynamic barcodes; reliability; smartphones; transmission
【Paper Link】 【Pages】:325-328
【Authors】: Lei Yang ; Yekui Chen ; Chen Chen ; Xiang-Yang Li ; Xuan Ding ; Yi Guo ; Yunhao Liu
【Abstract】: In many applications, we have to identify an object and then locate the object to within high precision (centimeter- or millimeter-level). Tracking mobile RFID tags in real time has been a daunting task, especially challenging for achieving high precision. We achieve these three goals by leveraging the phase value of the backscattered signal, provided by the COTS RFID readers, to estimate the location of the object. To illustrate the basic idea of our system, we firstly focus on a simple scenario where the tag is moving along a fixed track known to the system. We propose Differential Augmented Hologram (DAH) which will facilitate the instant tracking of the mobile RFID tag to a high precision. We then devise a comprehensive solution to accurately recover the tag's moving trajectory and its locations, relaxing the assumption of knowing tag's track function in advance.
【Keywords】: localization; rfid; tracking
【Paper Link】 【Pages】:329-332
【Authors】: Lan Zhang ; Xiang-Yang Li ; Wenchao Huang ; Kebin Liu ; Shuwei Zong ; Xuesi Jian ; Puchun Feng ; Taeho Jung ; Yunhao Liu
【Abstract】: In this demo, we propose a proof-of-concept networking system for smart glasses, through which users can express their interest and connect to a target simply by a gaze. Our system iGaze is a visual attention driven networking suite: an iGaze glass (hardware) and a networking protocol VAN (software). Our glass is a low-cost head-mounted glass with a camera, orientation sensors, microphone and speakers, which are embedded with our software for visual attention capture and networking. A visual attention driven networking protocol (VAN) is carefully designed and implemented. In VAN, we design an energy efficient and highly accurate visual attention determination scheme using single camera to capture user's communication interest and a double-matching scheme based on visual direction detection and Doppler effect of acoustic signal to lock the target devices. iGaze has separated and modularized hardware and software design. It can run on top of existing networking protocols, e.g., Wi-Fi.
【Keywords】: attention driven networking; device paring; gaze tracking; smart glasses
【Paper Link】 【Pages】:333-336
【Authors】: Pengfei Zhou ; Weiming Chan ; Shiqi Jiang ; Jiajue Ou ; Mo Li ; Guobin Shen
【Abstract】: The phone attitude is an essential input to many smartphone applications. Based on in-depth understanding of the nature of the MEMS gyroscope and other IMU sensors, we propose A3 - an accurate and automatic attitude detector for commodity smartphones. In the demo, we show the performance of our attitude tracking algorithm and its usability in attitude-based mobile applications.
【Keywords】: attitude-based applications; gyroscope; imu sensors; mobile phone attitude
【Paper Link】 【Pages】:337-340
【Authors】: Omid Abari ; Hariharan Rahul ; Dina Katabi
【Abstract】: Implementing distributed wireless protocols at the physical layer today is challenging because different nodes have different clocks, each of which has slightly different frequencies. This causes the nodes to have frequency offset relative to each other. As a result, transmitted signals from these nodes do not combine in a predictable manner over time. Past work tackles this challenge and builds distributed PHY layer systems by attempting to address the effects of the frequency offset and compensating for it in the transmitted signals. In this extended abstract, we address this challenge by addressing the root cause - the different clocks with different frequencies on the different nodes. We present AirClock, a new wireless coordination primitive that enables multiple nodes to act as if they are driven by a single clock that they receive wirelessly over the air. AirClock presents a synchronized abstraction to the physical layer, and hence enables direct implementation of diverse kinds of distributed PHY protocols. We illustrate AirClock's versatility by using it to build two different systems: (1) distributed MIMO, and (2) distributed rate adaptation for wireless sensors, and show that they can provide significant performance benefits over today's systems.
【Keywords】: clock synchronization; distributed mimo; wireless; wireless sensors
【Paper Link】 【Pages】:341-344
【Authors】: Maryam Ahmadi ; Jianping Pan ; Lei Zheng ; Lin Cai ; Fei Tong
【Abstract】: Geometrical distance distribution (GDD) between nodes in wireless communication networks plays a significant role in modeling network performance metrics. Existing work on obtaining GDD assumes the network geometry to be a regular one, such as circle and square. Due to the various complex effects of wireless signals, however, the network geometry usually is quite irregular. Therefore, this paper proposes a novel systematic and unified approach to obtain the GDD between two random nodes associated with arbitrary network geometries. To the best of our knowledge, this is the first work that will fill the gap in the literature of this field.
【Keywords】: arbitrary geometries; geometrical distance distribution; line kinematic measure; wireless communication networks
【Paper Link】 【Pages】:345-346
【Authors】: Shegufta Bakht Ahsan ; Nitin Vaidya
【Abstract】: Distributed Coordination Function (DCF) is defined in IEEE 802.11 standard, which is widely used in practice. Despite of its wide use, it has several limitations. Because of the idle and collision times, it suffers from poor channel utilization. Besides, the control packets, particularly, Acknowledgement (ACK), consume non-trivial amount of bandwidth. Though the number of control bits in an ACK frame is small, the added overheads like the preamble, packet header etc. make the situation worse. In this paper, we propose a scheme called Overheard ACK where the explicit ACK frame has been eliminated by using the leverage of packet overhearing. Also, by incorporating explicit and implicit token-passing, this protocol attempts to schedule transmissions without having to use random access, dramatically reducing the idle time and collision time. Simulation results using NS2 confirm that this protocol significantly outperforms the conventional 802.11 DCF.
【Keywords】: packet overhearing; token passing
【Paper Link】 【Pages】:347-350
【Authors】: Abdulla Alasaadi ; Tamer Nadeem
【Abstract】: In this paper, we describe the in-lane communication framework that enables the communication between vehicles on the same lane. The system creates a unique signature for each lane using smartphone inertial sensors. The calculated lane signature will be attached with each broadcasted message, where other vehicles on the street compare it with their own lane signature to decide if the received message came from a vehicle on the same lane or not. The paper concentrates on finding the right features that can be used to identify a lane in a road. To identify a lane with a unique signature, the paper proposes a combination of driving features and road features. The paper uses the inertial sensors because the current GPS systems are not accurate enough to locate vehicles with a lane level accuracy. The ability to establish a communication channel between vehicles on the same lane can enhance the road safety and enable several interesting navigation applications.
【Keywords】: communication; lane detection; mobile computing; traffic
【Paper Link】 【Pages】:351-354
【Authors】: Changsheng Chen ; Wai Ho Mow
【Abstract】: 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.
【Keywords】: 2d barcode; corner detection; matched filtering
【Paper Link】 【Pages】:355-358
【Authors】: Xin B. Gao ; Jie Tian ; Guiling Wang
【Abstract】: 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.
【Keywords】: distracted driving; dtm; gps; smartphone; transportation mode
【Paper Link】 【Pages】:359-362
【Authors】: Mahanth Gowda ; Gordon Stewart ; Geoffrey Mainland ; Bozidar Radunovic ; Dimitrios Vytiniotis ; Doug Patterson
【Abstract】: Software-defined radio (SDR) brings the flexibility of software to the domain of wireless protocol design, promising an ideal platform both for research and innovation and rapid deployment of new protocols on existing hardware. However, existing SDR programming platforms require either careful hand-tuning of low-level code, negating many of the advantages of software, or are too slow to be useful in the real world. We present Ziria, the first software-defined radio programming platform that is both easily programmable and performant. Ziria introduces a novel programming model tailored to wireless physical layer tasks and captures the inherent and important distinction between data and control paths in this domain. Ziria provides the capability of implementing a real-time WiFi PHY running at 20 MHz.
【Keywords】: compilers; languages; signal processing; wireless
【Paper Link】 【Pages】:363-366
【Authors】: Xiping Hu ; Jun-qi Deng ; Wenyan Hu ; Georgios Fotopoulos ; Edith C. H. Ngai ; Zhengguo Sheng ; Min Liang ; Xitong Li ; Victor C. M. Leung ; Sidney Fels
【Abstract】: Driving is an integral part of our everyday lives, but it is also a time when people are uniquely vulnerable. Poor road condition, traffic congestion and long driving time may bring negative emotion to drivers and increase the chance of traffic accidents. We propose SAfeDJ, a situation-aware in-car music delivery application, which turns people's trips into pleasant journeys and driving into a safe and enjoyable activity. SAfeDJ aims at helping drivers to diminish fatigue and negative emotion. It is built on a vehicular healthcare platform that enables communications among drivers and integrates with multiple types of sensors to promote safe driving. Prototype implementation and initial results of SAfeDJ have demonstrated its desired functionality in drivers' daily lives and feasibility for real-world deployment.
【Keywords】: cloud; situation-aware; vehicular sensor application
【Paper Link】 【Pages】:367-370
【Authors】: Huan Huang ; Hailong Sun ; Guoqing Ma ; Xu Wang ; Xudong Liu
【Abstract】: 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.
【Keywords】: caching; mobile web browsing; prefetching
【Paper Link】 【Pages】:371-374
【Authors】: Woo Sung Jung ; Keun Woo Lim ; Young-Bae Ko
【Abstract】: This poster proposes an adaptive flow control scheme for reliable packet delivery of Universal Serial Bus (USB) services when they are transmitted through wireless medium. In the future, USB can be utilized with the Wi-Fi technology to provide Wi-Fi USB (WSB). However, the data transmission of Wi-Fi and USB are asynchronous due to their different Medium Access Control (MAC) characteristics, which may result in buffer overflow. To prevent buffer overflow, we propose an adaptive flow control scheme that can select between the various transmission speeds of USB to match with the bandwidth provided by the Wi-Fi layer. Preliminary results of the proposed scheme evaluated via the NS-3 shows that the packet delivery ratio of USB data can be substantially increased, thus providing better USB reliability.
【Keywords】: flow control; wi-fi p2p; wireless serial bus
【Paper Link】 【Pages】:375-378
【Authors】: Kleomenis Katevas ; Hamed Haddadi ; Laurissa Tokarchuk
【Abstract】: With the rapid rise in variety of available smartphones today and their rich sensing capabilities, there is an increasing interest in using mobile sensing in large-scale experiments and commercial applications. Motivated by the lack of a universal, multi-platform library, in this paper we present SensingKit, an efficient, open-source, client-server system that supports both iOS and Android mobile devices. SensingKit is capable of continuous sensing the device's motion (Accelerometer, Gyroscope, Magnetometer), location (GPS) and proximity to other smartphones (Bluetooth Smart). The data are temporarily saved to the device's memory and transmitted to a server for further analysis over any Internet connection. We believe that this platform will be beneficial to all researchers and developers who need to perform mobile sensing in their applications and experiments.
【Keywords】: android; ios; mobile sensing; motion data; spatio-temporal data
【Paper Link】 【Pages】:379-382
【Authors】: Tao Li ; Wei Xi ; Shaojie Tang ; Jinsong Han ; Jizhong Zhao ; Xiang-Yang Li ; Zhi Wang ; Zhiping Jiang
【Abstract】: Locating objects labeled with RFID tags is an important issue which should be addressed in many applications, such as warehouse management, goods management in supermarket and finding of lost objects. Some existing works use large numbers of reference tags which involve lots of manpower to deploy them. Others achieve high accuracy, but rely on sophisticated equipments which are hardly available in large scale to the industry. This work exploits the radiation pattern of existing directional panel antenna which is steerable and derives angle-of-arrival (AoA) information from the energy reflected by the target tag when the antenna is rotating. We use Commercial Off-The-Shelf (COTS) equipments and get median position accuracy of 29cm in our preliminary experiment.
【Keywords】: antenna; localization; radiation pattern; rfid; tag
【Paper Link】 【Pages】:383-386
【Authors】: Tianxing Li ; Chuankai An ; Andrew T. Campbell ; Xia Zhou
【Abstract】: We present HiLight, a new form of screen-camera communication without the need of any coded images (e.g. barcodes) for off-the-shelf smart devices. HiLight hides information underlying any images shown on a LED or an OLED screen, so that camera-equipped smart devices can fetch the information by turning their cameras to the screen. HiLight achieves this by leveraging the orthogonal transparency (alpha) channel, a well-known concept in computer graphics, to embed bits into pixel translucency changes without the need of modifying pixel color values. We demonstrated HiLight's feasibility using smartphones. By offering an unobtrusive, flexible, and lightweight communication channel between screens and cameras, HiLight opens up opportunities for new HCI and context-aware applications to emerge, e.g. smart glass communicates with screens for additional personalized information to realize augmented reality.
【Keywords】: screen-camera link; visible light communication
【Paper Link】 【Pages】:387-390
【Authors】: Robert LiKamWa ; Eddie Reyes ; Lin Zhong
【Abstract】: While computer vision algorithms and libraries have enabled and accelerated the adoption of vision processing into mobile and wearable applications, vision is a resource-hungry operation, and is thus not efficient enough to run on multiple applications simultaneously. However, we observe that many vision algorithms share identical sets of frames and features to perform their analyses, computed from the same library calls. Leveraging this observation, we design a split-process architecture to retrofit existing vision libraries to allow applications to transparently share the computational, memory, and energy overhead of vision processing.
【Keywords】: remote execution; shared memory management; split-process
【Paper Link】 【Pages】:391-394
【Authors】: Meng Meng ; Kun Tan ; Wenjie Wang
【Abstract】: In this poster, we present a novel spectrum monitor, named AirEye, that monitors a wide spectrum band using only a narrowband radio. Unlike previous work, AirEye blindly extracts cyclic features from received waveform and performs classification without any prior knowledge on the transmitted signals. Although AirEye uses only a narrowband radio, it can still identify any signal that is wider than the radio bandwidth. Finally, AirEye exploits the signal sparsity in both radio and cyclic frequency dimensions to significantly speedup the feature extraction.
【Keywords】: blind classify; cyclic feature; scanning
【Paper Link】 【Pages】:395-396
【Authors】: Yong Niu ; Yong Li ; Depeng Jin
【Abstract】: Recently, millimeter wave communications in 60 GHz band have attracted considerable attention from academia, industry, and standards bodies. To overcome huge propagation loss, high gain directional antennas are used. Consequently, concurrent transmissions (spatial reuse) are enabled within a basic service set (BSS) and even among BSSs, which provides huge potential to improve the network capacity. In this paper, we propose a software-defined mmWave network architecture, where a centralized controller is introduced by abstracting the cross-layer control functions from the network layer to physical layer. Efficient coordination is achieved in this architecture to maximize the spatial reuse.
【Keywords】: millimeter wave communications; sdn; spatial reuse
【Paper Link】 【Pages】:397-400
【Authors】: Homin Park ; DaeHan Ahn ; Myounggyu Won ; Sang H. Son ; Taejoon Park
【Abstract】: In this work, we address a fundamental problem of distinguishing the driver from passengers using a fusion of embedded sensors (accelerometers, gyroscopes, microphones, and magnetic sensors) in a smart phone. Compared with the state-of-the-art solutions, a key property of our solution is non-intrusiveness, i.e., enabling accurate driver phone detection without relying on any particular situations, events, and dedicated hardware devices. Our system only utilizes naturally arising driver motions, i.e., sitting down sideways, closing the vehicle door, and starting the vehicle, to determine whether the user enters the vehicle from left or right and whether the user is seated in the front or rear seats.
【Keywords】: driver phone detection; driving safety; smartphone
【Paper Link】 【Pages】:401-404
【Authors】: Valentin Radu ; Panagiota Katsikouli ; Rik Sarkar ; Mahesh K. Marina
【Abstract】: The environmental context of a mobile device determines where/how it is used, which can be exploited for efficient operation and better usability. In this work we describe a general method using only the lightweight sensors on a smartphone to detect if a device is indoor or outdoor. Using semi-supervised machine learning techniques, our method automatically learns characteristics of new environments and devices, thereby achieves detection accuracy of over 90% even in unfamiliar circumstances. Therefore, it easily outperforms existing indoor-outdoor detection techniques based on static algorithms, or relying on energy hungry and unreliable GPS.
【Keywords】: context detection; indoor-outdoor; machine learning; smartphone sensing
【Paper Link】 【Pages】:405-408
【Authors】: David Ramírez ; Robert LiKamWa ; Jason Holloway
【Abstract】: Screen-to-camera visible-light communication links are fundamentally limited by inter-symbol interference, in which the camera receives multiple overlapping symbols in a single capture exposure. By determining interference constraints, we are able to decode symbols with multi-bit depth across all three color channels. We present Styrofoam, a coding scheme which optimally satisfies the constraints by inserting blank frames into the transmission pattern. The coding scheme improves upon the state-of-the-art in camera-based visible-light communication by: (1) ensuring a decode with at least half-exposure of colored multi-bit symbols, (2) limiting decode latency to two transmission frames, and (3) transmitting 0.4 bytes per grid block at the slowest camera's frame rate. In doing so, we outperform peer unsynchronized VLC transmission schemes by 2.9x. Our implementation on smartphone displays and cameras achieves 69.1 kbps.
【Keywords】: camera synchronization; mobile systems; visible light communications
【Paper Link】 【Pages】:409-412
【Authors】: Yanzhi Ren ; Chen Wang ; Yingying Chen ; Jie Yang
【Abstract】: Sleep monitoring has drawn increasingly attention as the quality and quantity of the sleep are important for maintaining a person's health and well-being. For example, inadequate and irregular sleep are usually associated with serious health problems such as fatigue, depression and cardiovascular disease. Traditional sleep monitoring systems, such as PSG, involve wearable sensors with professional installations, and thus are limited to clinical usage. Recent work in using smartphone sensors for sleep monitoring can detect several events related to sleep, such as body movement, cough and snore. Such coarse-grained sleep monitoring however is unable to detect the breathing rate which is a vital sign and health indicator. This work presents a fine-grained sleep monitoring system which is capable of detecting the breathing rate by leveraging smartphones. Our system exploits the readily available smartphone earphone that placed close to the user to capture the breath sound reliably. Given the captured acoustic signal, our system performs noise reduction to remove environmental noise and then identifies the breathing rate based on the signal envelope detection. Our experimental evaluation of six subjects over six months time period demonstrates that the breathing rate monitoring is highly accurate and robust under various environments. This strongly indicates the feasibility of using the smartphone and its earphone to perform continuous and noninvasive fine-grained sleep monitoring.
【Keywords】: breath rate detection; sleep monitoring; smartphone
【Paper Link】 【Pages】:413-416
【Authors】: Roberto Riggio ; Tinku Rasheed ; Mahesh K. Marina
【Abstract】: Programming wireless networks requires accounting for multiple complex operations, such as monitoring interference and allocating radio resources. Employing the Software-Defined Networking (SDN) paradigm eases the implementation of such tasks when augmented with suitable high-level programming abstractions. In this work, we present a set of programming abstractions modeling three fundamental aspects of a wireless networks, namely state management, resource provisioning, and network state collection. We also describe our proof-of-concept implementation of the proposed abstractions focusing on WiFi networks and show its use for realizing typical control tasks such as mobility management and traffic engineering as Network Apps.
【Keywords】: network management; programming abstractions; wifi
【Paper Link】 【Pages】:417-420
【Authors】: Ahmed Salem ; Tamer Nadeem
【Abstract】: Smartphones have created a strong tie with human beings. It is likely to have plenty of smartphones in the same proximity. However, users are limited with the capabilities of a single device. In this work we propose ColPhone a framework that facilitates collaboration between smartdevices in the vicinity to share their resources providing users hardware upgrade for their devices. Further, we implemented an application (3D Story Teller) on top of ColPhone, and measured the impact of collaboration on smartphone's power consumption.
【Keywords】: android; bluetooth; collaboration; pure data; smartphone; wifi-p2p
【Paper Link】 【Pages】:421-424
【Authors】: Hossein Shafagh ; Anwar Hithnawi
【Abstract】: This paper presents a proximity-based authentication approach for the Internet of Things (IoT) that works in-band by solely utilizing the wireless communication interface. The novelty of this approach lies in its reliance on ambient radio signals to infer proximity within about one second, and in its ability to expose imposters located several meters away. We identify relevant features sensed from the RF channel to establish a notion of proximity across co-located low-power devices. We introduce our proximity-based authentication protocol and show the feasibility of our approach with an early prototype using off-the-shelf 802.15.4 sensors and an evaluation conducted in a real-world environment.
【Keywords】: internet of things; security; wireless communication
【Paper Link】 【Pages】:425-428
【Authors】: Petros Spachos ; Dimitrios Hatzinakos
【Abstract】: Scalability and sustainability are two fundamental requirements in Wireless Sensor Networks (WSNs). Inch scale sensor nodes can operate unattended for long periods if they have sufficient energy sources. In this work, a Self-Powered Sensor Network (SPSN) testbed is introduced. SPSN is cost-efficient and has large-scale deployability. It combines cognitive networking principles with efficient routing approaches and energy harvesting techniques. SPSN is used for indoor CO2 monitoring as well as for outdoor gas leak detection. The performance of the system for channel estimation at an outdoor environment is examined. Experimental results show that SPSN can be used for a plethora of other applications as well.
【Keywords】: cognitive radio networks; routing protocols; self-powered wireless sensor networks; testbeds
【Paper Link】 【Pages】:429-432
【Authors】: Petros Spachos ; Dimitrios Hatzinakos
【Abstract】: An appealing solution for unattended surveillance and monitoring applications is Self-powered Wireless Sensor Networks (WSNs). One of the main reasons is that the energy which is derived from power harvesting can significantly extend the network lifetime. Consequently, the network can work unattended for long periods. However, WSNs are characterized by multi-hop lossy links and resource constrained nodes while they have to face the coexistence problem with other applications. Opportunistic Routing (OR) is a routing paradigm to improve network performance in lossy wireless networks. At the same time, Cognitive Radio (CR) technology enables unlicensed operation in licensed bands. In this work, a combination of these two research approaches in a novel routing protocol is presented. A Spectrum and Energy Aware Opportunistic Routing (SEA-OR) protocol is proposed and designed for Self-powered WSNs. Moreover, a prioritization scheme which balances the packet advancement, the residual energy and the link reliability is introduced. Preliminary results show an improvement in network lifetime and delivery ratio. The performance of the introduced protocol is also evaluated in prototypes.
【Keywords】: cognitive radio networks; cognitive routing protocols; self-powered wireless sensor networks
【Paper Link】 【Pages】:433-436
【Authors】: Li Sun ; Souvik Sen ; Dimitrios Koutsonikolas
【Abstract】: The continuously increasing number of smartphones and tablets allow the users to access Wireless LANs (WLANs) while undergoing different types of mobility, posing new challenges to wireless protocols. Current history-based WLAN protocols do not work well in mobile settings where wireless conditions change rapidly. Thus, today's WLANs need to be able to determine the type of the client's mobility and employ appropriate strategies in order to sustain high performance. While previous work tried to detect mobility using hints from sensors available in mobile devices, in this work, we demonstrate how different mobility modes can be distinguished by using physical layer information - Channel State Information (CSI) and Time-of-Flight (ToF) - available at commodity APs, with no modifications on the client side. Our testbed experiments show that our mobility classification algorithm achieves more than 92% accuracy in a variety of scenarios. In addition, we demonstrate how fine-grained mobility determination can be exploited to greatly improve performance of client roaming and MIMO beamforming.
【Keywords】: mobility; phy layer; wireless; wlan
【Paper Link】 【Pages】:437-440
【Authors】: Güliz Seray Tuncay ; Kirill Varshavskiy ; Robin Kravets ; Klara Nahrstedt
【Abstract】: SaveAlert is an adaptive framework for crowd-monitoring and danger-detection using off-the-shelf smartphones and other peripherals such as smartwatches. It is a system that provides users with an increased awareness of their surroundings by detecting and notifying them of impending danger, by relying only on sensor data collected from the users. Our framework's novelty is in how it performs efficient sensor data collection from potentially a large number of people by limiting the disturbance and stress on the existing Wi-Fi and cellular infrastructure. To the best of our knowledge, this is the first crowd-monitoring framework that takes advantage of peer-to-peer connections to perform local aggregation to alleviate the stress on existing infrastructures for better scalability and efficiency.
【Keywords】: crowd dynamics; crowd monitoring; crowd sensing; danger detection; safety
【Paper Link】 【Pages】:441-444
【Authors】: Kang Zhao ; Dingyi Fang ; Xiaojiang Chen ; Yuan Zhang ; Weike Nie ; Tianzhang Xing
【Abstract】: This poster introduces MoveLoc, a system that locates a moving object without carrying any devices from detecting Doppler shifts reflected off the moving object. It works even if the object walking or running in different directions without any training. MoveLoc does not require the user to carry any communication devices, yet its accuracy exceeds current moving object localization systems using Radio Signal Strength(RSS). We implement the system and evaluate the performance on moving person by experiments. Experimental result shows that MoveLoc achieves an average location accuracy of 0.69 meters and reduces the equipment deployment density compared with other known wireless moving object localization approaches using RSS.
【Keywords】: device-free localization; doppler shifts; wireless sensing
【Paper Link】 【Pages】:445-446
【Authors】: Victor Bahl ; Leonard Kleinrock ; Randy H. Katz ; Imrich Chlamtac
【Abstract】: The great French writer, historian and philosopher Voltaire once asked, "Is there anyone so wise as to learn by the experience of others?" In celebration of the 20th MobiCom conference, join us for a thought provoking discussion between pioneers of our field on the lessons they have learned over their illustrious career paths that accelerated the pace of technology adoption and enabled world-wide societal impact. Learn from our heroes as they share with us gems of wisdom on how to choose a great problem, what to avoid and how to be successful as you build your own remarkable careers.
【Keywords】: cloud computing; internet; mobile computing; technology lessons
【Paper Link】 【Pages】:447-458
【Authors】: Ye-Sheng Kuo ; Pat Pannuto ; Ko-Jen Hsiao ; Prabal Dutta
【Abstract】: We explore the indoor positioning problem with unmodified smartphones and slightly-modified commercial LED luminaires. The luminaires-modified to allow rapid, on-off keying-transmit their identifiers and/or locations encoded in human-imperceptible optical pulses. A camera-equipped smartphone, using just a single image frame capture, can detect the presence of the luminaires in the image, decode their transmitted identifiers and/or locations, and determine the smartphone's location and orientation relative to the luminaires. Continuous image capture and processing enables continuous position updates. The key insights underlying this work are (i) the driver circuits of emerging LED lighting systems can be easily modified to transmit data through on-off keying; (ii) the rolling shutter effect of CMOS imagers can be leveraged to receive many bits of data encoded in the optical transmissions with just a single frame capture, (iii) a camera is intrinsically an angle-of-arrival sensor, so the projection of multiple nearby light sources with known positions onto a camera's image plane can be framed as an instance of a sufficiently-constrained angle-of-arrival localization problem, and (iv) this problem can be solved with optimization techniques. We explore the feasibility of the design through an analytical model, demonstrate the viability of the design through a prototype system, discuss the challenges to a practical deployment including usability and scalability, and demonstrate decimeter-level accuracy in both carefully controlled and more realistic human mobility scenarios.
【Keywords】: angle-of-arrival; image processing; indoor localization; mobile phones
【Paper Link】 【Pages】:459-470
【Authors】: Liqun Li ; Guobin Shen ; Chunshui Zhao ; Thomas Moscibroda ; Jyh-Han Lin ; Feng Zhao
【Abstract】: Diversity in training data density and environment locality is intrinsic in the real-world deployment of indoor localization systems and has a major impact on the performance of existing localization approaches. In this paper, through micro-benchmarks, we find that fingerprint-based approaches are preferable in scenarios where a dense database is available; while model-based approaches are the method of choice in the case of sparse data. It should be noted, however, that practical situations are complex. A single deployment often features both sparse and dense sampled areas. Furthermore, the internal layout affects the propagation of radio signals and exhibits environmental impacts. A certain number of measurement samples may be sufficient for one part of the building, but entirely insufficient for another. Thus, finding the right indoor localization algorithm for a given large-scale deployment is challenging, if not impossible; there is no one-size-fits-all indoor localization approach. Realizing the fundamental fact that the quality of the location database capturing the actual radio map dictates localization accuracy, in this paper, we propose Modellet, an algorithmic approach that optimally approximates the actual radio map by unifying model-based and fingerprint-based approaches. Modellet represents the radio map using a fingerprint-cloud that incorporates both measured real fingerprints and virtual fingerprints, which are computed from models with a local support, based on the key concept of the supporting set. We evaluate Modellet with data collected from an office building as well as 13 large-scale deployment venues (shopping malls and airports), located across China, U.S., and Germany. Comparing Modellet with two representative baseline approaches, RADAR and EZPerfect, demonstrates that Modellet effectively adapts to different data densities and environmental conditions, substantially outperforming existing approaches.
【Keywords】: fingerprint; indoor localization; model
【Paper Link】 【Pages】:471-482
【Authors】: Yuanqing Zheng ; Guobin Shen ; Liqun Li ; Chunshui Zhao ; Mo Li ; Feng Zhao
【Abstract】: We present Travi-Navi - a vision-guided navigation system that enables a self-motivated user to easily bootstrap and deploy indoor navigation services, without comprehensive indoor localization systems or even the availability of floor maps. Travi-Navi records high quality images during the course of a guider's walk on the navigation paths, collects a rich set of sensor readings, and packs them into a navigation trace. The followers track the navigation trace, get prompt visual instructions and image tips, and receive alerts when they deviate from the correct paths. Travi-Navi also finds the most efficient shortcuts whenever possible. We encounter and solve several challenges, including robust tracking, shortcut identification, and high quality image capture while walking. We implement Travi-Navi and conduct extensive experiments. The evaluation results show that Travi-Navi can track and navigate users with timely instructions, typically within a 4-step offset, and detect deviation events within 9 steps.
【Keywords】: image direction; indoor navigation; self-deployable system
【Paper Link】 【Pages】:483-494
【Authors】: Swarun Kumar ; Stephanie Gil ; Dina Katabi ; Daniela Rus
【Abstract】: Recent years have seen the advent of new RF-localization systems that demonstrate tens of centimeters of accuracy. However, such systems require either deployment of new infrastructure, or extensive fingerprinting of the environment through training or crowdsourcing, impeding their wide-scale adoption. We present Ubicarse, an accurate indoor localization system for commodity mobile devices, with no specialized infrastructure or fingerprinting. Ubicarse enables handheld devices to emulate large antenna arrays using a new formulation of Synthetic Aperture Radar (SAR). Past work on SAR requires measuring mechanically controlled device movement with millimeter precision, far beyond what commercial accelerometers can provide. In contrast, Ubicarse's core contribution is the ability to perform SAR on handheld devices twisted by their users along unknown paths. Ubicarse is not limited to localizing RF devices; it combines RF localization with stereo-vision algorithms to localize common objects with no RF source attached to them. We implement Ubicarse on a HP SplitX2 tablet and empirically demonstrate a median error of 39 cm in 3-D device localization and 17 cm in object geotagging in complex indoor settings.
【Keywords】: localization; phy; sar; wi-fi; wireless
【Paper Link】 【Pages】:495-506
【Authors】: Jouya Jadidian ; Dina Katabi
【Abstract】: This paper bridges wireless communication with wireless power transfer. It shows that mobile phones can be charged remotely, while in the user's pocket by applying the concept of MIMO beamforming. However, unlike MIMO beamforming in communication systems which targets the radiated field, we transfer power by beamforming the non-radiated magnetic field and steering it toward the phone. We design MagMIMO, a new system for wireless charging of cell phones and portable devices. MagMIMO consumes as much power as existing solutions, yet it can charge a phone remotely without being removed from the user's pocket. Furthermore, the phone need not face the charging pad, and can charge independently of its orientation. We have built MagMIMO and demonstrated its ability to charge the iPhone and other smart phones, while in the user's pocket.
【Keywords】: beamforming; energy; magnetic resonance; mimo; mobile and wearable devices; wireless power transfer
【Paper Link】 【Pages】:507-518
【Authors】: Hassan Khan ; Aaron Atwater ; Urs Hengartner
【Abstract】: Security and usability issues with pass-locks on mobile devices have prompted researchers to develop implicit authentication (IA) schemes, which continuously and transparently authenticate users using behavioural biometrics. Contemporary IA schemes proposed by the research community are challenging to deploy, and there is a need for a framework that supports: different behavioural classifiers, given that different apps have different requirements; app developers using IA without becoming domain experts; and real-time classification on resource-constrained mobile devices. We present Itus, an IA framework for Android that allows the research community to improve IA schemes incrementally, while allowing app developers to adopt these improvements at their own pace. We describe the Itus framework and how it provides: ease of use: Itus allows app developers to use IA by changing as few as two lines of their existing code - on the other hand, Itus provides an oracle capable of making advanced recommendations should developers wish to fine-tune the classifiers; flexibility: developers can deploy Itus in an application-specific manner, adapting to their unique needs; extensibility: researchers can contribute new behavioural features and classifiers without worrying about deployment particulars; low performance overhead: Itus operates with minimal performance overhead, allowing app developers to deploy it without compromising end-user experience. These goals are accomplished with an API allowing individual stakeholders to incrementally improve Itus without re-engineering new systems. We implement Itus in two demo apps and measure its performance impact. To our knowledge, Itus is the first open-source extensible IA framework for Android that can be deployed off-the-shelf.
【Keywords】: behavioural biometrics; implicit authentication; security
【Paper Link】 【Pages】:519-530
【Authors】: Chieh-Jan Mike Liang ; Nicholas D. Lane ; Niels Brouwers ; Li Zhang ; Börje Karlsson ; Hao Liu ; Yan Liu ; Jun Tang ; Xiang Shan ; Ranveer Chandra ; Feng Zhao
【Abstract】: Scalable and comprehensive testing of mobile apps is extremely challenging. Every test input needs to be run with a variety of contexts, such as: device heterogeneity, wireless network speeds, locations, and unpredictable sensor inputs. The range of values for each context, e.g. location, can be very large. In this paper we present Caiipa, a cloud service for testing apps over an expanded mobile context space in a scalable way. It incorporates key techniques to make app testing more tractable, including a context test space prioritizer to quickly discover failure scenarios for each app. We have implemented Caiipa on a cluster of VMs and real devices that can each emulate various combinations of contexts for tablet and phone apps. We evaluate Caiipa by testing 265 commercially available mobile apps based on a comprehensive library of real-world conditions. Our results show that Caiipa leads to improvements of 11.1x and 8.4x in the number of crashes and performance bugs discovered compared to conventional UI-based automation (i.e., monkey-testing).
【Keywords】: contextual fuzzing; mobile app testing
【Paper Link】 【Pages】:531-542
【Authors】: Mian Dong ; Tian Lan ; Lin Zhong
【Abstract】: Energy accounting determines how much a software principal contributes to the total system energy consumption. It is the foundation for evaluating software and for operating system based energy management. While various energy accounting policies have been tried, there is no known way to evaluate them directly simply because it is hard to track all hardware usage by software in a heterogeneous multicore system like modern smartphones and tablets. In this work, we argue that energy accounting should be formulated as a cooperative game and that the Shapley value provides the ultimate ground truth for energy accounting policies. We reveal the important flaws of existing energy accounting policies based on the Shapley value theory and provide Shapley value-based energy accounting, a practical approximation of the Shapley value, for battery-powered mobile systems. We evaluate this approximation against existing energy accounting policies in two ways: (i) how well they identify the top energy consuming applications, and (ii) how effective they are in system energy management. Using a prototype based on Texas Instruments Pandaboard and smartphone workload, we experimentally demonstrate existing energy accounting policies can deviate by 400% in attributing energy consumption to running applications and can be up to 25% less effective in system energy management when compared to Shapley value-based energy accounting.
【Keywords】: energy accounting; energy management; mobile systems
【Paper Link】 【Pages】:543-544
【Authors】: Kit Colbert
【Abstract】: The next frontier of mobility -- from behavioral analysis for the app ecosystem to geolocation on steroids -- presents challenges as tough as the opportunities are expansive. What is the TCP/IP of the Internet of Things era? And who will build it? Hyper-aware smartphones that know you're in the snack aisle are great for retailers, but who's addressing the security implications? The industry is charting its strategic course, but there is an exciting opportunity for researchers and academia to provide the coordinates towards the solutions to mobility's hardest problems. In this keynote, Kit Colbert, Chief Technology Officer for End-User Computing at VMware, will discuss the unsolved challenges in mobility, and the possibilities that will be unlocked when the industry and academia partner on finding the answers.
【Keywords】: applications; mobility; security; smartphones; software
【Paper Link】 【Pages】:545-556
【Authors】: Yi-Chao Chen ; Lili Qiu ; Yin Zhang ; Guangtao Xue ; Zhenxian Hu
【Abstract】: Networks are constantly generating an enormous amount of rich diverse information. Such information creates exciting opportunities for network analytics. However, a major challenge to enable effective network analytics is the presence of missing data, measurement errors, and anomalies. Despite significant work in network analytics, fundamental issues remain: (i) the existing works do not explicitly account for anomalies or measurement noise, and incur serious performance degradation under significant noise or anomalies, and (ii) they assume network matrices have low-rank structure, which may not hold in reality. To address these issues, in this paper we develop LENS decomposition, a novel technique to accurately decompose a network matrix into a low-rank matrix, a sparse anomaly matrix, an error matrix, and a small noise matrix. LENS has the following nice properties: (i) it is general: it can effectively support matrices with or without anomalies, and having low-rank or not, (ii) its parameters are self tuned so that it can adapt to different types of data, (iii) it is accurate by incorporating domain knowledge, such as temporal locality, spatial locality, and initial estimate (e.g., obtained from models), (iv) it is versatile and can support many applications including missing value interpolation, prediction, and anomaly detection. We apply LENS to a wide range of network matrices from 3G, WiFi, mesh, sensor networks, and the Internet. Our results show that LENS significantly out-performs state-of-the-art compressive sensing schemes.
【Keywords】: anomaly detection; compressive sensing; traffic matrix
【Paper Link】 【Pages】:557-568
【Authors】: Pengyu Zhang ; Pan Hu ; Vijay Pasikanti ; Deepak Ganesan
【Abstract】: This paper argues for a clean-slate redesign of wireless sensor systems to take advantage of the extremely low power consumption of backscatter communication and emerging ultra-low power sensor modalities. We make the case that existing sensing architectures incur substantial overhead for a variety of computational blocks between the sensor and RF front end - while these overheads were negligible on platforms where communication was expensive, they become the bottleneck on backscatter-based systems and increase power consumption while limiting throughput. We present a radically new design that is minimalist, yet efficient, and designed to operate end-to-end at tens of μWs while enabling high-data rate backscatter at rates upwards of many hundreds of Kbps. In addition, we demonstrate a complex reader-driven MAC layer that jointly considers energy, channel conditions, data utility, and platform constraints to enable network-wide throughput optimizations. We instantiate this architecture on a custom FPGA-based platform connected to microphones, and show that the platform consumes 73x lower power and has 12.5x higher throughput than existing backscatter-based sensing platforms.
【Keywords】: architecture; backscatter; sensor; wireless
【Paper Link】 【Pages】:569-580
【Authors】: Sayandeep Sen ; Michael Griepentrog ; Jongwon Yoon ; Suman Banerjee
【Abstract】: The work in this paper is a systematic research and engineering effort in exploring the design space of multi-interface wireless repeater systems. We present the design, implementation and evaluation of a wireless repeater system, Multifacet, which opportunistically utilizes multiple interfaces to enhance capacity. The system is designed to be transparent to application endpoints and does not need any end application modifications for adoption. Multifacet incorporates several techniques to achieve efficient bandwidth utilization across multiple interfaces -- (a) coordinated channel sharing, (b) a simplified backpressure based striping technique, (c) a single link abstraction, and (d) the ability to seamlessly migrate a client to the optimal channel. Multifacet is implemented on off-the-shelf dual band wireless repeater and demonstrates high speeds (337 Mbps) operation. On average, Multifacet performs 50% better than traditional AP/repeater setups, and in the best case, more than 2x better.
【Keywords】: dual radio ap; implementation; wireless repeater
【Paper Link】 【Pages】:581-592
【Authors】: Yibo Zhu ; Xia Zhou ; Zengbin Zhang ; Lin Zhou ; Amin Vahdat ; Ben Y. Zhao ; Haitao Zheng
【Abstract】: Today's network control and management traffic are limited by their reliance on existing data networks. Fate sharing in this context is highly undesirable, since control traffic has very different availability and traffic delivery requirements. In this paper, we explore the feasibility of building a dedicated wireless facilities network for data centers. We propose Angora, a low-latency facilities network using low-cost, 60GHz beamforming radios that provides robust paths decoupled from the wired network, and flexibility to adapt to workloads and network dynamics. We describe our solutions to address challenges in link coordination, link interference and network failures. Our testbed measurements and simulation results show that Angora enables large number of low-latency control paths to run concurrently, while providing low latency end-to-end message delivery with high tolerance for radio and rack failures.
【Keywords】: 60ghz wireless; data centers; wireless beamforming
【Paper Link】 【Pages】:593-604
【Authors】: Guanhua Wang ; Yongpan Zou ; Zimu Zhou ; Kaishun Wu ; Lionel M. Ni
【Abstract】: Recent literature advances Wi-Fi signals to "see" people's motions and locations. This paper asks the following question: Can Wi-Fi "hear" our talks? We present WiHear, which enables Wi-Fi signals to "hear" our talks without deploying any devices. To achieve this, WiHear needs to detect and analyze fine-grained radio reflections from mouth movements. WiHear solves this micro-movement detection problem by introducing Mouth Motion Profile that leverages partial multipath effects and wavelet packet transformation. Since Wi-Fi signals do not require line-of-sight, WiHear can "hear" people talks within the radio range. Further, WiHear can simultaneously "hear" multiple people's talks leveraging MIMO technology. We implement WiHear on both USRP N210 platform and commercial Wi-Fi infrastructure. Results show that within our pre-defined vocabulary, WiHear can achieve detection accuracy of 91% on average for single individual speaking no more than 6 words and up to 74% for no more than 3 people talking simultaneously. Moreover, the detection accuracy can be further improved by deploying multiple receivers from different angles.
【Keywords】: interference cancelation; micro-motion detection; moving pattern recognition; wi-fi radar
【Paper Link】 【Pages】:605-616
【Authors】: Pengfei Zhou ; Mo Li ; Guobin Shen
【Abstract】: The phone attitude is an essential input to many smartphone applications, which has been known very difficult to accurately estimate especially over long time. Based on in-depth understanding of the nature of the MEMS gyroscope and other IMU sensors commonly equipped on smartphones, we propose A3 - an accurate and automatic attitude detector for commodity smartphones. A3 primarily leverages the gyroscope, but intelligently incorporates the accelerometer and magnetometer to select the best sensing capabilities and derive the most accurate attitude estimation. Extensive experimental evaluation on various types of Android smartphones confirms the outstanding performance of A3. Compared with other existing solutions, A3 provides 3x improvement on the accuracy of attitude estimation.
【Keywords】: attitude calibration; gyroscope; imu sensors; mobile phone attitude
【Paper Link】 【Pages】:617-628
【Authors】: Yan Wang ; Jian Liu ; Yingying Chen ; Marco Gruteser ; Jie Yang ; Hongbo Liu
【Abstract】: Activity monitoring in home environments has become increasingly important and has the potential to support a broad array of applications including elder care, well-being management, and latchkey child safety. Traditional approaches involve wearable sensors and specialized hardware installations. This paper presents device-free location-oriented activity identification at home through the use of existing WiFi access points and WiFi devices (e.g., desktops, thermostats, refrigerators, smartTVs, laptops). Our low-cost system takes advantage of the ever more complex web of WiFi links between such devices and the increasingly fine-grained channel state information that can be extracted from such links. It examines channel features and can uniquely identify both in-place activities and walking movements across a home by comparing them against signal profiles. Signal profiles construction can be semi-supervised and the profiles can be adaptively updated to accommodate the movement of the mobile devices and day-to-day signal calibration. Our experimental evaluation in two apartments of different size demonstrates that our approach can achieve over 96% average true positive rate and less than 1% average false positive rate to distinguish a set of in-place and walking activities with only a single WiFi access point. Our prototype also shows that our system can work with wider signal band (802.11ac) with even higher accuracy.
【Keywords】: activity recognition; channel state information(csi); device-free; location-oriented; wifi