The 19th Annual International Conference on Mobile Computing and Networking, MobiCom'13, Miami, FL, USA, September 30 - October 04, 2013. ACM 【DBLP Link】
【Paper Link】 【Pages】:1-2
【Authors】: Flavio Bonomi
【Abstract】: This keynote presentation will focus on the challenges and opportunities imposed on mobility and wireless communications technologies by the emerging and explosive needs of the future Internet of Things. As traditional (wireless) networking meets the "real world", with its highly mobile requirements, its noisy and lossy environments, its need to optimize communications across multiple, non-homogeneous wireless technologies, with often intermittent connectivity, its requirements for more deterministic exchanges, the urgent need of innovation and accelerated research into a number of relevant and exiting domains become apparent. We will describe the ICT Infrastructure developments needed to support these new requirements, and identify broad open mobility and wireless research topics, which may help catalyze innovation affecting our industry. In particular, among other topics, we will deal with the issue of IP mobility, and will discuss technologies responding to these requirements (LISP among them). We will then consider the need to support and manage non-homogeneous, multi-homed, highly lossy wireless connectivity, and will highlight the potential roles of Distributed Computing and of Network Coding in this domain. Finally, we will detail the deterministic networking requirements arising in a number of Internet of Things verticals, and highlight progress towards the definition and standardization of techniques enabling more predictable exchanges even in wireless networks.
【Keywords】: deterministic networking; distributed computing; internet of things; lisp; multi-homing; network coding
【Paper Link】 【Pages】:3-14
【Authors】: Jue Wang ; Fadel Adib ; Ross A. Knepper ; Dina Katabi ; Daniela Rus
【Abstract】: Modern robots have to interact with their environment, search for objects, and move them around. Yet, for a robot to pick up an object, it needs to identify the object's orientation and locate it to within centimeter-scale accuracy. Existing systems that provide such information are either very expensive (e.g., the VICON motion capture system valued at hundreds of thousands of dollars) and/or suffer from occlusion and narrow field of view (e.g., computer vision approaches). This paper presents RF-Compass, an RFID-based system for robot navigation and object manipulation. RFIDs are low-cost and work in non-line-of-sight scenarios, allowing them to address the limitations of existing solutions. Given an RFID-tagged object, RF-Compass accurately navigates a robot equipped with RFIDs toward the object. Further, it locates the center of the object to within a few centimeters and identifies its orientation so that the robot may pick it up. RF-Compass's key innovation is an iterative algorithm formulated as a convex optimization problem. The algorithm uses the RFID signals to partition the space and keeps refining the partitions based on the robot's consecutive moves.We have implemented RF-Compass using USRP software radios and evaluated it with commercial RFIDs and a KUKA youBot robot. For the task of furniture assembly, RF-Compass can locate furniture parts to a median of 1.28 cm, and identify their orientation to a median of 3.3 degrees.
【Keywords】: RF localization; RFIDs; optimization; robot mobile manipulation
【Paper Link】 【Pages】:15-26
【Authors】: Wenjun Hu ; Hao Gu ; Qifan Pu
【Abstract】: A key challenge for smartphone based visual communication over screen-camera links is imperfect frame synchronization. The difficulty arises from frame rate diversity and variability due to camera capability, lighting conditions, and system factors. On the 4 smartphone cameras we tested, the frame rate varies between 8 and 30 frames per second. If the transmit frame rate is too high, the receiver might lose original frames or capture mixed frames, which are normally not decodable. Previous systems simply reduce the effective screen frame rate to be half the camera frame capture rate, to guarantee receiving a decodable frame every other frame. This under-utilizes the transmitter side capacity and is inefficient. We achieve frame synchronization with LightSync, which features in-frame color tracking to decode imperfect frames and a linear erasure code across frames to recover lost frames. LightSync allows smooth communication between the screen and the camera at any combination of the transmit and receive frame rates, as long as the receive rate is at least half the transmit rate. This means that each receiver can scale the decoding performance with its own camera capability. Across several phones, our system can more than double the average throughput compared to previous approaches.
【Keywords】: inter-frame erasure coding; per-line tracking; screen-camera links; unsynchronized communication
【Paper Link】 【Pages】:27-38
【Authors】: Qifan Pu ; Sidhant Gupta ; Shyamnath Gollakota ; Shwetak Patel
【Abstract】: This paper presents WiSee, a novel gesture recognition system that leverages wireless signals (e.g., Wi-Fi) to enable whole-home sensing and recognition of human gestures. Since wireless signals do not require line-of-sight and can traverse through walls, WiSee can enable whole-home gesture recognition using few wireless sources. Further, it achieves this goal without requiring instrumentation of the human body with sensing devices. We implement a proof-of-concept prototype of WiSee using USRP-N210s and evaluate it in both an office environment and a two- bedroom apartment. Our results show that WiSee can identify and classify a set of nine gestures with an average accuracy of 94%.
【Keywords】: gesture recognition; whole-home interaction; wireless sensing
【Paper Link】 【Pages】:39-50
【Authors】: Muhammad Shahzad ; Alex X. Liu ; Arjmand Samuel
【Abstract】: With the rich functionalities and enhanced computing capabilities available on mobile computing devices with touch screens, users not only store sensitive information (such as credit card numbers) but also use privacy sensitive applications (such as online banking) on these devices, which make them hot targets for hackers and thieves. To protect private information, such devices typically lock themselves after a few minutes of inactivity and prompt a password/PIN/pattern screen when reactivated. Passwords/PINs/patterns based schemes are inherently vulnerable to shoulder surfing attacks and smudge attacks. Furthermore, passwords/PINs/patterns are inconvenient for users to enter frequently. In this paper, we propose GEAT, a gesture based user authentication scheme for the secure unlocking of touch screen devices. Unlike existing authentication schemes for touch screen devices, which use what user inputs as the authentication secret, GEAT authenticates users mainly based on how they input, using distinguishing features such as finger velocity, device acceleration, and stroke time. Even if attackers see what gesture a user performs, they cannot reproduce the behavior of the user doing gestures through shoulder surfing or smudge attacks. We implemented GEAT on Samsung Focus running Windows, collected 15009 gesture samples from 50 volunteers, and conducted real-world experiments to evaluate GEAT's performance. Experimental results show that our scheme achieves an average equal error rate of 0.5% with 3 gestures using only 25 training samples.
【Keywords】: authentication; gesture; locking/unlocking; mobile touch screen devices
【Paper Link】 【Pages】:51-62
【Authors】: Shuai Wang ; Song Min Kim ; Yunhuai Liu ; Guang Tan ; Tian He
【Abstract】: Wireless communication essentially occurs in a broadcast medium with concurrent receptions. Recent works [34, 41] have shown clear evidence that wireless links are not independent and that transmissions from a transmitter to multiple receivers are correlated, a phenomenon that has profound implications for the performance of network protocols such as broadcast, multi-cast, opportunistic forwarding and network coding. In this paper, we show how link correlation can significantly impact broadcast. We present the design and implementation of CorLayer, a general supporting layer for energy efficient reliable broadcast that carefully blacklists certain poorly correlated wireless links. This method uses only one-hop information, which makes it work in a fully distributed manner and introduces minimal communication overhead. The highlight of our work is CorLayer's broad applicability and effectiveness. Our system effort is indeed significant. We integrate CorLayer transparently with sixteen state-of-the-art broadcast protocols specified in thirteen publications [1, 3, 18, 19, 23, 25--27, 32, 36, 38--40] on three physical testbeds running TelosB, MICAz, and GreenOrbs nodes, respectively. The experimental results show that CorLayer remarkably improves energy efficiency across a wide spectrum of broadcast protocols and that the total number of packet transmissions can be reduced consistently by 47% on average.
【Keywords】: IEEE 802.15.4; energy efficiency; protocol; wireless
【Paper Link】 【Pages】:63-74
【Authors】: Abhijnan Chakraborty ; Vishnu Navda ; Venkata N. Padmanabhan ; Ramachandran Ramjee
【Abstract】: To minimize battery drain due to background communication in cellular-connected devices such as smartphones, the duration for which the cellular radio is kept active should be minimized. This, in turn, calls for scheduling the background communication so as to maximize the throughput. It has been recognized in prior work that a key determinant of throughput is the wireless link quality. However, as we show here, another key factor is the load in the cell, arising from the communication of other nodes. Unlike link quality, the only way, thus far, for a cellular client to obtain a measure of load has been to perform active probing, which defeats the goal of minimizing the active duration of the radio. In this paper, we address the above dilemma by making the following contributions. First, we show experimentally that to obtain good throughput, considering link quality alone is insufficient, and that cellular load must also be factored in. Second, we present a novel technique called LoadSense for a cellular client to obtain a measure of the cellular load, locally and passively, that allows the client to determine the ideal times for communication when available throughput to the client is likely to be high. Finally, we present the Peek-n-Sneak protocol, which enables a cellular client to "peek" into the channel and "sneak" in with its background communication when the conditions are suitable. When multiple clients in a cell perform Peen-n-Sneak, it enables them to coordinate their communications, implicitly and in an entirely distributed manner, akin to CSMA in wireless LANs, helping improve throughput (and reduce energy drain) for all. Our experimental evaluation shows overall device energy savings of 20-60% even when Peek-n-Sneak is deployed incrementally.
【Keywords】: 3G; 4G; LTE; background transfers; cellular; energy saving; load
【Paper Link】 【Pages】:75-86
【Authors】: Sarfraz Nawaz ; Christos Efstratiou ; Cecilia Mascolo
【Abstract】: Studies of automotive traffic have shown that on average 30% of traffic in congested urban areas is due to cruising drivers looking for parking. While we have witnessed a push towards sensing technologies to monitor real-time parking availability, instrumenting on-street parking throughout a city is a considerable investment. In this paper, we present ParkSense, a smartphone based sensing system that detects if a driver has vacated a parking spot. ParkSense leverages the ubiquitous Wi-Fi beacons in urban areas for sensing unparking events. It utilizes a robust Wi-Fi signature matching approach to detect driver's return to the parked vehicle. Moreover, it uses a novel approach based on the rate of change of Wi-Fi beacons to sense if the user has started driving. We show that the rate of change of the observed beacons is highly correlated with actual user speed and is a good indicator of whether a user is in a vehicle. Through empirical evaluation, we demonstrate that our approach has a significantly smaller energy footprint than traditional location sensors like GPS and Wi-Fi based positioning while still maintaining sufficient accuracy.
【Keywords】: Wi-Fi fingerprinting; on-street parking; smartphone sensing
【Paper Link】 【Pages】:87-98
【Authors】: Guan-Hua Tu ; Chunyi Peng ; Hongqi Wang ; Chi-Yu Li ; Songwu Lu
【Abstract】: Both voice and data are indispensable services in current cellular networks. In this work, we study the inter-play of voice and data in operational LTE networks. We assess how the popular CSFB-based voice service affects the IP-based data sessions in 4G LTE networks, and visa versa. Our findings reveal that the interference between them is mutual. On one hand, voice calls may incur throughput drop, lost 4G connectivity, and application aborts for data sessions. One the other hand, users may miss incoming voice calls when turning on data access. The fundamental problem is that, signaling and control for circuit-switched voice and packet-switched data have dependency and coupling effect via the LTE phone client. We further propose fixes to the identified issues.
【Keywords】: cellular networks; mobile data services; voice call
【Paper Link】 【Pages】:99-110
【Authors】: Karthikeyan Sundaresan ; Mustafa Y. Arslan ; Shailendra Singh ; Sampath Rangarajan ; Srikanth V. Krishnamurthy
【Abstract】: Cloud-based radio access networks (C-RAN) have been proposed as a cost-efficient way of deploying small cells. Unlike conventional RANs, a C-RAN decouples the baseband processing unit (BBU) from the remote radio head (RRH), allowing for centralized operation of BBUs and scalable deployment of light-weight RRHs as small cells. In this work, we argue that the intelligent configuration of the front-haul network between the BBUs and RRHs, is essential in delivering the performance and energy benefits to the RAN and the BBU pool, respectively. We then propose FluidNet - a scalable, light-weight framework for realizing the full potential of C-RAN. FluidNet deploys a logically re-configurable front-haul to apply appropriate transmission strategies in different parts of the network and hence cater effectively to both heterogeneous user profiles and dynamic traffic load patterns. FluidNet's algorithms determine configurations that maximize the traffic demand satisfied on the RAN, while simultaneously optimizing the compute resource usage in the BBU pool. We prototype FluidNet on a 6 BBU, 6 RRH WiMAX C-RAN testbed. Prototype evaluations and large-scale simulations reveal that FluidNet's ability to re-configure its front-haul and tailor transmission strategies provides a 50% improvement in satisfying traffic demands, while reducing the compute resource usage in the BBU pool by 50% compared to baseline transmission schemes.
【Keywords】: DAS; FFR; cellular; cloud-ran; front-haul
【Paper Link】 【Pages】:111-122
【Authors】: Jeremy Blackburn ; Rade Stanojevic ; Vijay Erramilli ; Adriana Iamnitchi ; Konstantina Papagiannaki
【Abstract】: Voice and data traffic growth over the last several years has become a major challenge for cellular operators with a direct impact on revenues, infrastructure investments, and end-user performance. The economics of these operators depend on various incentives used to attract users in the form of unlimited, buffet-like voice/sms/data packages. However, our understanding of the effects of user behavior under these offerings on operator revenues/costs remains poor. Using two years of detailed usage information of ~1 million users across three services, voice, sms and data, combined with payment and cost information, we study how user behavior affects the economics of cellular operators. We discover that around 20% of the users consume more resources than what they pay for and hence are non-profitable. In addition to the individual user behavior, we study how the user interactions in the call graph affect the operator's revenues and cost, drawing on tools from social network analysis. We develop a framework that incorporates both the individual and social user behavior for studying how volume caps influence the revenues and the traffic costs. Using this framework we empirically show that volume caps can increase the difference between the revenues and the traffic costs of the studied operator by a factor of 2, while affecting only 16% of the existing user base.
【Keywords】: cross-subsidization; network effects; user behavior
【Paper Link】 【Pages】:123-126
【Authors】: Joshua Joy ; Yu-Ting Yu ; Mario Gerla ; Samuel Wood ; James Mathewson ; Mark-Oliver Stehr
【Abstract】: First responders at the edge of the network rely on situation awareness updates to arrive in a timely matter, even when the fixed infrastructure is unavailable. The technical advancements of the commercial mobile phones make them capable of supporting such requirements under very disruptive network conditions. In this demo, we present a network architecture that exploits partial caches by utilizing network coding to deliver large files (e.g. images) to first responders. The architecture is based on a content centric network platform called ICEMAN(Information CEntric Mobile Ad-hoc Networking) and runs on Android phones. We demonstrate our system in a file dissemination scenario in a CORE/EMANE network emulation. We measure file delivery ratio, latency, and network overhead and report significant improvements that network coding achieves over fragmentation.
【Keywords】: ICN; MANET; ad-hoc; network coding
【Paper Link】 【Pages】:127-130
【Authors】: Joongheon Kim ; Feiyu Meng ; Peiyao Chen ; Hilmi E. Egilmez ; Dilip Bethanabhotla ; Andreas F. Molisch ; Michael J. Neely ; Giuseppe Caire ; Antonio Ortega
【Abstract】: This demo abstract describes an initial design of a new adaptive video streaming protocol for device-to-device WiFi-based mobile platforms and its software implementation. For the demonstration, two mobile servers and two mobile users will be deployed verifying that our device-to-device adaptive video streaming implementation works with desirable user experience.
【Keywords】: adpative video streaming; android; device-to-device; mobile platforms
【Paper Link】 【Pages】:131-134
【Authors】: Lien-Wu Chen ; Po-Chun Chou
【Abstract】: In this paper, we design and implement a lane-level cooperative collision avoidance (LCCA) system using vehicle-to-vehicle communications. The LCCA system applies vehicular sensor networks to preventing chain vehicle collisions, which allows vehicles with merely onboard sensors to prevent such collisions on the road because of sharp stops. To the best of our knowledge, this is the first CCA system that does not use inaccurate GPS locations and costly roadside infrastructures to avoid chain vehicle collisions. LCCA employs inter-vehicle communications and onboard sensing to form warning groups, where each warning group is a set of vehicles that drive along the same lane and every pair of adjacent cars is within a certain distance. Only single-hop transmissions are needed to join/leave a warning group, thus keeping the group maintenance overhead low. When a sudden braking is taken in a warning group, LCCA can quickly propagate warning messages among group members. This paper demonstrates our current prototype.
【Keywords】: IEEE 802.11p; V2V communication; collision avoidance; traffic safety; vehicular sensor network
【Paper Link】 【Pages】:135-138
【Authors】: Heikki Mahkonen ; Teemu Rinta-aho ; Tero Kauppinen ; Mohit Sethi ; Jimmy Kjällman ; Patrik Salmela ; Tony Jokikyyny
【Abstract】: This demo presents a Machine-to-Machine (M2M) service platform running on an OpenStack cloud environment. Access to this platform is secured with authentication based on 3GPP standardized Generic Bootstrapping Architecture (GBA). The M2M network in this testbed consists of Raspberry Pi gateways and resource-constrained devices such as Arduinos. These devices have associated sensors, that report physical data such as temperature, and actuators such as LEDs, that respond to actuation commands. In this demo, the sensor data is authenticated and integrity protected end-to-end with public-key elliptic curve digital signature algorithm (ECDSA). Lastly, the demo testbed includes a web-based cloud management interface referred to as the "IoT Portal". This portal allows a system administrator to specify pre-configured Virtual Machine (VM) images with custom applications. As an example, a M2M Web service is installed into the VMs. This web service collects and displays authenticated and verified sensor data and can also be used to send actuator commands.
【Keywords】: cloud computing; generic bootstrapping architecture; internet of things; machine-to-machine; openstack; security
【Paper Link】 【Pages】:139-142
【Authors】: Wenjian Huang ; Wai Ho Mow
【Abstract】: As 2D barcodes become more and more popular, their new applications, like mobile marketing, give a strong motivation for embedding visual information in them. Information stored on a 2D barcode, being printed on paper or shown on a display device, can be delivered to people via a camera phone with suitable decoding software. The barcoding system can be viewed as a communication system with key functional modules, including channel coding, modulation, channel estimation, demodulation and channel decoding. By applying advanced communications principles, a way to integrate a picture into a 2D barcode (called PiCode) is developed. By extending the idea, a way to integrate a video into a series of 2D barcodes, called ViCode, is also developed. To realize PiCode and ViCode, new modulation and demodulation schemes are designed. Based on our channel estimation technique, a new decoding scheme for low-density parity-check (LDPC) codes is devised to provide more robust error rate performance than traditional 2D barcodes. A US patent and a Chinese patent have already been filed based on the innovative methods developed for PiCode.
【Keywords】: 2D barcode; 3D barcode; decoder; display-camera communication channel; embedded picture and video; encoder
【Paper Link】 【Pages】:143-146
【Authors】: Jiansong Zhang ; Kun Tan
【Abstract】: In this demo, we propose to use multiple inexpensive off-the-shelf radios to build the FAIR system that can be flexibly configured to realize (1) non-contiguous spectrum access (2) MIMO and beamforming (3) constructing wider-band radio. While non-contiguous spectrum access and MIMO/beamforming are naturally supported by the FAIR system, we further develop radio bonding technique for constructing wider-band radio. Radio bonding provides a cost effective alternative to proprietory radio development that it can realize a non-existing wider-band radio using multiple commodity narrower-band radios. We demonstrate FAIR and radio bonding based on Sora 2.0.
【Keywords】: Sora 2.0; fair; radio bonding; wider-band radio
【Paper Link】 【Pages】:147-150
【Authors】: Martin Florian ; Simeon Andreev ; Ingmar Baumgart
【Abstract】: For smart traffic applications like dynamic route planning, communication between traffic participants is of high importance. Traditional approaches rely on centralized, server-based communication architectures, which raises scalability and privacy concerns. To address these problems, we proposed OverDrive, an overlay-based geocast service that is applicable in smart traffic scenarios and not prone to the shortcomings of centralized designs. Here, we present an interactive demonstrator of the OverDrive protocol that visualizes OverDrive's neighborhood structures and routing approach in a realistic and highly mobile traffic scenario. Our demonstrator is realized as an extension to the overlay simulation framework OverSim.
【Keywords】: geocast; overlay networks; peer-to-peer
【Paper Link】 【Pages】:151-154
【Authors】: Ahmed Elbagoury ; Moustafa Youssef ; Dongyue Xue ; Eylem Ekici
【Abstract】: Efficient scheduling of wireless resources has always been one of the most challenging tasks for wireless networks. To achieve throughput-optimality, traditional back-pressure algorithms calculate a maximal weight matching at each time slot. However, these algorithms need centralized scheduling with high complexity, and thus are not suitable for practical distributed implementations. A class of distributed queue-length-based CSMA algorithms have been proposed that achieve throughput optimality, which we refer to as regular throughput-optimal. These algorithms suffer from two problems: large delays, and temporal starvation. In this demo we demonstrate the operation of the v(t)-regulated CSMA algorithm that mitigates these two problems while provably retaining throughput optimality. The demo allows the participants to see the the performance advantage of v(t)-regulated CSMA over queue-length-based CSMA algorithms and change the different system parameters.
【Keywords】: csma-based scheduling; delay-based scheduling; optimal wireless scheduling
【Paper Link】 【Pages】:155-158
【Authors】: Justin Yackoski ; Babak Azimi-Sadjadi ; Ali Namazi ; Alexey Bogaevskiy ; Jason Li ; Yalin Evren Sagduyu ; Renato Levy
【Abstract】: In this demonstration, we present new capabilities of Intelligent Automation Inc. (IAI) Radio Frequency Network Emulation Simulation Tool (RFnestTM) (www.i-a-i.com/rfnest). RFnestTM is a Field Programmable Gate Array (FPGA) based network channel emulator that allows all of the channels of a full network of radio nodes to be emulated in real time, with all communication nodes experiencing a realistic channel impulse response. This allows RFnestTM to be used for protocol testing, replaying field tests, and model validation. RFnestTM has a modular design with three main capabilities: 1) FPGA based emulation hardware with RF front ends that allows nodes with real radios to send their RF signal over an emulated channel without any modification to the radio, 2) modeling of time-varying channel impulse responses within the emulation hardware, with channel properties based on mobility defined with a scripted or interactive Graphic User Interface (GUI) environment, and 3) integration with network emulators and monitoring functionality that allows the user to instantiate, manage, and monitor real and virtual network nodes within the scenario. In the new version of RFnestTM we now support: Frequency programmability: The new RFnestTM allows users to change the center frequency through software from 800 Mhz to 2.7GHz. Increased bandwidth: RFnestTM supports a bandwidth of 60 MHz. Higher fidelity channel modeling: Through software and hardware updates RFnestTM support wireless channels with up to 20 taps and a wide range of Doppler frequencies. MIMO: RFnestTM now supports different combination of MIMO channel between transmitters and receivers. We will demonstrate the capabilities of RFnestTM with scenarios, including multi-hop bulk data transfer in mixed real virtual network, bulk data transmission at 900MHz and video transfer between two real nodes.
【Keywords】: FPGA; emulation; frequency; network; radio; simulation
【Paper Link】 【Pages】:159-162
【Authors】: Bastian Bloessl ; Michele Segata ; Christoph Sommer ; Falko Dressler
【Abstract】: We just released an Open Source receiver that is able to decode IEEE 802.11a/g/p Orthogonal Frequency Division Multiplexing (OFDM) frames in software. This is the first Software Defined Radio (SDR) based OFDM receiver supporting channel bandwidths up to 20MHz that is not relying on additional FPGA code. Our receiver comprises all layers from the physical up to decoding the MAC packet and extracting the payload of IEEE 802.11a/g/p frames. In our demonstration, visitors can interact live with the receiver while it is decoding frames that are sent over the air. The impact of moving the antennas and changing the settings are displayed live in time and frequency domain. Furthermore, the decoded frames are fed to Wireshark where the WiFi traffic can be further investigated. It is possible to access and visualize the data in every decoding step from the raw samples, the autocorrelation used for frame detection, the subcarriers before and after equalization, up to the decoded MAC packets. The receiver is completely Open Source and represents one step towards experimental research with SDR.
【Keywords】: IEEE 802.11a/g/p; OFDM; receiver
【Paper Link】 【Pages】:163-166
【Authors】: Clayton Shepard ; Hang Yu ; Lin Zhong
【Abstract】: Many-antenna base stations are a rapidly growing field in wireless research. A plethora of new theoretical techniques have been recently proposed for many-antenna base stations and networks. However, without experimental validation, it is difficult or impossible to predict the practicality and performance of these techniques in real hardware, under complex, rapidly varying, real-world conditions. Indeed, there is a significant demand for a flexible many-antenna research platform which supports rapid prototyping and validation of new massive-MIMO techniques. Leveraging our experience building Argos, a 64-antenna base station prototype, we have designed and built ArgosV2, a compact, powerful, and scalable many-antenna research platform based on WARP. In addition to the physical hardware and mechanical design, we are developing a software framework, ArgosLab, which will provide synchronization and channel estimation, greatly reducing the development effort for a wide range of massive-MIMO techniques. ArgosV2 is intended to provide ultimate scalability and programmability for experimental massive-MIMO research. The modular architecture and real-time capability of ArgosV2 can support up to 100s of base station antennas and 10s of users with streaming applications. For our demonstration, we will unveil a 96-antenna base station which supports real-time streaming applications to 32 users simultaneously.
【Keywords】: MRT; beamforming; conjugate; distributed-mimo; large-scale antenna systems (LSAS); many-antenna; massive-mimo; multi-user mimo; network-mimo; zero-forcing
【Paper Link】 【Pages】:167-170
【Authors】: Virgilios Passas ; Kostas Chounos ; Stratos Keranidis ; Wei Liu ; Lieven Hollevoet ; Thanasis Korakis ; Iordanis Koutsopoulos ; Ingrid Moerman ; Leandros Tassiulas
【Abstract】: Cognitive radio systems have gathered a lot of research interest during the last decade. Accuracy of spectrum sensing and efficiency of free spectrum utilization are considered as the primary objectives in this emerging technology, which promises a boost in wireless network performance, through exploitation of underutilized licensed frequency bands. As the focus of researchers is usually on these two major challenges, other aspects have been in part underestimated. In this work, we consider two factors that are rather important for evaluation of cognitive platforms, namely sensing delay and energy efficiency. The first is related to the latency induced by the spectrum sensing process and its impact on sensing efficiency, which is tightly connected to both the QoS performance of secondary users and the protection of primary users. On the other hand, energy consumption is considered as a crucial issue in all types of wireless communications, due to restricted battery autonomy of mobile devices, as well as for moving towards "greener" solutions in telecommunications. Therefore, it is important to extend existing testbed experimentation tools and develop new ones, in order to equip cognitive testbeds with such advanced monitoring capabilities. In this work, we present a monitoring procedure that has been directly integrated in the experimentation tools of the CREW testbed federation and demonstrate how it aids in the online evaluation of four different cognitive platforms in terms of the aforementioned metrics.
【Keywords】: crew project; energy consumption; spectrum sensing
【Paper Link】 【Pages】:171-174
【Authors】: Hidekazu Suzuki ; Katsuhiro Naito ; Kazuma Kamienoo ; Tatsuya Hirose ; Akira Watanabe
【Abstract】: With the spread of mobile devices, there is a growing demand for direct communication between users. However, under recent complex IP networks, it is extremely hard to establish a direct connection between devices. In order to solve the problem, authors have been proposing a new end-to-end communication architecture called "Network Traversal with Mobility" (NTMobile). In NTMobile, applications in the mobile device establish an end-to-end connection by using virtual IPv4/IPv6 addresses in the NTMobile network independent from real IP networks. In this demo, we will show that Android smartphones can make free communication with each other without any constraint such as an NAT traversal problem in IPv4 networks and incompatibility between IPv4 and IPv6 architectures.
【Keywords】: IPv4/IPv6; NAT traversal; android; handover; mobility
【Paper Link】 【Pages】:175-178
【Authors】: Jie Li ; Li Liu ; Feng Xia
【Abstract】: Socially-aware networking provides a promising paradigm for data forwarding by exploiting the involved nodes' social properties in mobile social networks. However, individuals' learning capability and awareness to the dynamic environment have not been well explored in the literature. In this paper, we give a brief introduction of an interest-based scheme called BEEINFO. Inspired by swarm intelligence, BEEINFO takes advantage of individuals' perceiving and learning capability to gather information of density and social tie during communication. Moreover, it classifies communities based on nodes' interests and distinguishes data forwarding into situations of inter-community and intra-community. Furthermore, BEEINFO performs efficient message scheduling and buffer management to improve performance. The simulation results show that BEEINFO outperforms PROPHET and Epidemic in message delivery ratio, overhead and hop count, except for average latency.
【Keywords】: forwarding; interest; socially-aware networking; swarm intelligence
【Paper Link】 【Pages】:179-182
【Authors】: Abdelrahman Asal ; Ahmad Mamdouh ; Ahmed Salama ; Moamen Elgendy ; Moamen Mokhtar ; Muhammed Elsayed ; Moustafa Youssef
【Abstract】: Cognitive Radio Networks (CRNs) provide a solution to increase the utilization of the scarce radio frequency spectrum. Building testbeds for CRNs is one of the main challenges that can affect the wide deployability of such networks. Many testbeds were proposed for testing CRN routing protocols, but most of them are either pure simulations or require high deployment cost for buying and maintaining the needed hardware devices on a large scale. We propose CRESCENT: a modular framework for testing CRNs routing protocols with cost-efficient and large-scale deployability. CRESCENT is based on general purpose computers without the need for any special devices leveraging their built-in Wi-Fi interfaces as the default interface. The framework is built on top of Click modular router to ensure the ease of the development of new routing protocols while providing new modules that are essential for cognitive radio protocols.
【Keywords】: cognitive radio networks; cognitive routing protocols; emulation; testbeds
【Paper Link】 【Pages】:183-186
【Authors】: Daniel Philip Venmani ; Yvon Gourhant ; Djamal Zeghlache
【Abstract】: In this article we illustrate that, management of network resources can yield notably different performances leading to different restoration behaviors -- for different network topologies. In consideration towards this, we first briefly summarize our earlier work on a novel fault restoration mechanism. The proposed mechanism addresses the problem of finding the minimum bandwidth cooperative route in the backhaul of mobile network operators that is shared among multiple operators. We then present our recent results on the extended performance evaluations of the same, for four different synthetic network topologies carried out using extensive simulations. Through these evaluations, we conclude on the best topology that mobile network operators should construct in order for them to maximally benefit by the proposed cooperative routing scheme to yield optimum performance for their capital expenditure.
【Keywords】: maximally disjoint paths; multi-topology wireless backhaul networks; path computation algorithms
【Paper Link】 【Pages】:187-190
【Authors】: Cheng Bo ; Lan Zhang ; Xiang-Yang Li ; Qiuyuan Huang ; Yu Wang
【Abstract】: In this work, we present SilentSense, a framework to authenticate users silently and transparently by exploiting the user touch behavior biometrics and leveraging the integrated sensors to capture the micro-movement of the device caused by user's screen-touch actions. By tracking the fine-detailed touch actions of the user, we build a "touch-based biometrics" model of the owner by extracting some principle features, and then verify whether the current user is the owner or guest/attacker. When using the smartphone, the unique operating pattern of the user is detected and learnt by collecting the sensor data and touch events silently. When users are mobile, the micro-movement of mobile devices caused by touch is suppressed by that due to the large scale user-movement which will render the touch-based biometrics ineffective. To address this, we integrate a movement-based biometrics for each user with previous touch-based biometrics. We conduct extensive evaluations of our approaches on the Android smartphone, we show that the user identification accuracy is over 99%.
【Keywords】: SilentSense; identification; mobile device
【Paper Link】 【Pages】:191-194
【Authors】: Güliz Seray Tuncay ; Giacomo Benincasa ; Ahmed Helmy
【Abstract】: Opportunistic sensing is a novel approach that exploits the sensing capabilities offered by smartphones and users' mobility to sense large scale areas without requiring the deployment of sensors in-situ. In this work, we propose a novel framework for fully distributed, opportunistic sensing which coherently integrates two main components that operate in DTN mode: i. participant recruitment and ii. data collection. We evaluate our approach by considering alternative implementations of the framework, and by measuring their performance via extensive trace-based simulations. Our results show how the performances of the considered protocols vary, depending on the particular scenario, and suggest guidelines for future development of distributed opportunistic sensing systems.
【Keywords】: DTN; crowdsensing; mobile computing; opportunistic sensing
【Paper Link】 【Pages】:195-198
【Authors】: Cheng Bo ; Xiang-Yang Li ; Taeho Jung ; XuFei Mao ; Yue Tao ; Lan Yao
【Abstract】: We present SmartLoc, a localization system to estimate the location and the traveling distance by leveraging the lower-power inertial sensors embedded in smartphones as a supplementary to GPS. To minimize the negative impact of sensor noises, SmartLoc exploits the intermittent strong GPS signals and uses the linear regression to build a prediction model which is based on the trace estimated from inertial sensors and the one computed from the GPS. Furthermore, we utilize landmarks (e.g., bridge, traffic lights) detected automatically and special driving patterns (e.g., turning, uphill, and downhill) from inertial sensory data to improve the localization accuracy when the GPS signal is weak. Our evaluations of SmartLoc in the city demonstrates its technique viability and significant localization accuracy improvement compared with GPS and other approaches: the error is approximately 20m for 90% of time while the known mean error of GPS is 42.22m.
【Keywords】: inertial sensor; localization; smartloc
【Paper Link】 【Pages】:199-202
【Authors】: Cheng Bo ; Xuesi Jian ; Xiang-Yang Li ; XuFei Mao ; Yu Wang ; Fan Li
【Abstract】: In this work, we address a critical task of detecting the user behavior of driving and texting simultaneously using smartphones. We propose, design, and implement TEXIVE which achieves the goal of distinguishing drivers and passengers, and detecting texting operations during driving utilizing irregularities and rich micro-movements of users. Without relying on any external infrastructures and additional devices, and no need to bring any modification to vehicles, TEXIVE is able to successfully detect dangerous operations with good sensitivity, specificity and accuracy. We conduct experimental study of TEXIVE with the help of a number of volunteers using various vehicles and smartphones. Our results indicate that TEXIVE has a classification accuracy of 87.18%, and precision of 96.67%.
【Keywords】: classification; smartphone; texive
【Paper Link】 【Pages】:203-205
【Authors】: Afnan Fahim ; Abderrahmen Mtibaa ; Khaled A. Harras
【Abstract】: In this paper, we consider an environment in which computational offoading is adopted amongst mobile devices. We call such an environment a mobile device cloud (MDC). In this work, we highlight via emulation, experimenation and real measurements, the potential gain in computation time and energy consumption that can be achieved by offoading tasks within an MDC. We also propose and develop an experimental platform to enable researchers create and experiment with novel offoading algorithms in MDCs.
【Keywords】: computation offoading; measurements; mobile device clouds
【Paper Link】 【Pages】:207-210
【Authors】: Mahmudur Rahman ; Jaime Ballesteros ; Bogdan Carbunar ; Naphtali Rishe ; Athanasios V. Vasilakos
【Abstract】:
【Keywords】: location verification; privacy; social networks
【Paper Link】 【Pages】:211-214
【Authors】: Petri Savolainen ; Sumi Helal ; Jukka Reitmaa ; Kai Kuikkaniemi ; Giulio Jacucci ; Mikko Rinne ; Marko Turpeinen ; Sasu Tarkoma
【Abstract】: Spaceify is a novel edge architecture and an ecosystem for smart spaces --- a technology that extends the mobile user view of today's common space services (e.g., WiFi) to a richer portfolio of space-centric, localized services and space-interactive applications.
【Keywords】: architecture; client-edge-server; ecosystem; smart space
【Paper Link】 【Pages】:215-218
【Authors】: Yuta Morisawa ; Yoshihiro Kawahara ; Tohru Asami
【Abstract】: Wireless LAN multicast can provide high quality location-aware content service. However, our research revealed that multicast might cause a significant increase in the power consumption. Flexible Multicast Service (FMS) which is defined in the IEEE 802.11v enables power efficient multicast service. In this paper, we prove that the FMS strategy is not optimal and a little extension on FMS will achieve great improvement in power efficiency without throughput or delay penalties.
【Keywords】: multimedia streaming; power saving; wireless LAN
【Paper Link】 【Pages】:219-222
【Authors】: Susumu Ishihara ; Nobuhiro Nakamura ; Yuya Niimi
【Abstract】: We propose a framework for efficiently disseminating large data items associated to locations where they are produced by vehicles and desired by drivers of different vehicles in a VANET. The framework consists of a scheme for aggregating drivers' demand for location dependent data using soft-state sketches, a scheme for understanding the condition of data dissemination, and a strategy for selecting data to be transmitted according to the aggregated demands and the condition of the existence of neighboring vehicles which have the same data.
【Keywords】: ad hoc networks; data dissemination
【Paper Link】 【Pages】:223-226
【Authors】: Mostafa Uddin ; Tamer Nadeem
【Abstract】: In this paper, we propose and addresses the challenge of designing a light-weight high-accuracy indoor/outdoor localization system (SpyLoc) for off-the-shelf smartphones. In SpyLoc, we want to leverages both the acoustic interface (microphone/speaker) and the Wi-Fi interface at the kernel-level of the smartphones as well as the inertial sensors in the smartphones to achieve high localization accuracy. In the ranging-based approach, we utilizes the RF-Beep ranging scheme[?], and in dead reckoning-based approach, we fuses the inertial sensors of the smartphone to estimate the direction and the distance of user's movements. In RF-Beep [?], we develope a ranging scheme that utilizes the Time-Difference-of-Arrival (TDoA) between the acoustic and the radio-frequency (RF) signal. The RF-Beep basically leverages the slow propagation speed of the acoustic signal with respect to the RF signal to estimate the relative range. The well known acoustic range based localization scheme, Cricket [?] also utilizes the same concept of using the difference in arrival times of concurrent transmissions of radio and ultrasound signals at the target device to infer the distance. Unlike the Cricket, which was designed with special hardware, our localization scheme is applicable to the smartphones. In RF-Beep, we address the different challenges of implementing such ranging scheme in smartphones by leveraging the existing functionalities of the audio driver and the WiFi driver. Further details on RF-Beep scheme could be found in~\cite{Uddin:RF}. The ranging based localization scheme typically requires at least three reference points (e.g., anchor points), in order to calculate the location. However all these three reference points must be in Line of Sight(LoS) to the target device. In \textit{SpyLoc} localization system, we use the combination of both ranging-based and dead reckoning approaches to reduce the constraint of having three LoS anchor/reference points all the time. The basic idea of the SpyLoc is to leverage the benefits of both the dead-reckoning and the ranging scheme to build a practical localization system. Given the high errors of the inertial sensors, SpyLoc uses a novel ranging scheme based on both the acoustic and WiFi interfaces to mitigate this error in order to improve the localization accuracy. Unlike the ranging-based or RF-based localization schemes that require multiple reference points (e.g., achor points), using the dead reckoning in SpyLoc reduces the required number of reference points to only one reference to locate and track users accurately. This low dependency on ranging scheme make SpyLoc practically applicable to high mobility environment. Finally, In the SpyLoc system, user's device (i.e. smartphone) works autonomously to determine its location. This system does not require any coordination from the nearby smartphones or from a central controller. Furthermore, this localization system does not require user's device to transmit any acoustic signal or RF messages to nearby smartphones. Therefore increasing the number of user's devices have no impact on the complexity of the SpyLoc system, which make SpyLoc a light-weight localization system. In addition, such characteristics make the localization system privacy preserving and energy efficient for the user's smartphone.
【Keywords】: localization; mobility; smartphones
【Paper Link】 【Pages】:227-230
【Authors】: Ghazale Hosseinabadi ; Nitin H. Vaidya
【Abstract】: This paper presents the design and performance evaluation of Concurrent-MAC, a MAC protocol for increasing concurrent transmissions in multi-AP wireless LANs. Based on SINR values between stations and APs, sets of concurrent transmitters are identified by the backhaul of APs. A station gaining access to the channel, schedules a set of its neighbors for concurrent transmissions. Neighbors chosen for concurrent transmission can start transmitting on the channel, immediately after they overhear the privilege given to them for concurrent transmission. Our simulation results show that, in dense wireless LANs, Concurrent-MAC can improve aggregate throughput significantly compared to 802.11 DCF.
【Keywords】: MAC-layer; concurrent transmissions; wireless lans
【Paper Link】 【Pages】:231-234
【Authors】: Paul Baumann ; Wilhelm Kleiminger ; Silvia Santini
【Abstract】: Predicting the arrival and residence time of individuals at their relevant places enables a plethora of novel applications. In this work we first analyze the theoretical predictability of arrival and residence times and then evaluate the performance of eight different residence time predictors. We show that these predictors tend to underestimate the time a user will spend at her relevant places.
【Keywords】: arrival time; predictability of human mobility; residence time
【Paper Link】 【Pages】:235-238
【Authors】: Yan Wang ; Jie Yang ; Hongbo Liu ; Yingying Chen ; Marco Gruteser ; Richard P. Martin
【Abstract】: We investigate using smartphone WiFi signals to track human queues, which are common in many business areas such as retail stores, airports, and theme parks. Real-time monitoring of such queues would enable a wealth of new applications, such as bottleneck analysis, shift assignments, and dynamic workflow scheduling. We take a minimum infrastructure approach and thus utilize a single monitor placed close to the service area along with transmitting phones. Our strategy extracts unique features embedded in the signal traces to infer the critical time points when a person reaches the head of the queue and finishes service, and from these inferences we derive a person's waiting and service times. We develop a feature driven approach in our system. Extensive experiments conducted both in the laboratory demonstrate that our system is robust to queues with different waiting time. We show that in spite of noisy signal readings, our methods can measure important time periods in queue (e.g., service and waiting times) to within a $10$ second resolution.
【Keywords】: Wi-Fi; human queue; smartphone
【Paper Link】 【Pages】:239-242
【Authors】: Jie Hui ; Kevin Lau
【Abstract】: T-Mobile USA is looking at all possible ways to optimize the quality of user experience (QoE) for our customers in while balanceing with our network resources and device energy consumptions needs. In the mobile smart phone world, users often have a the misperception that people often held about use experience is the faster the network speed is and, the faster the phone CPU speed is;, the better the quality of experience (QoE) will beis. On the contrary, we intend to use three practical examples to unveil the mystery behind the mobile network black box and illustrate it is actually the end-to-tend (E2E) latency which impacts the QoE of one of the most commonly used data services -- mobile browsing. A lengthy E2E latency due to rarely-understood and hard-to-uncovered phone or network issues may render a very poor browsing page loading speed time even if you have a super hero dual core smart phone with the fastest 4G network speed. In order to understand the E2E latency better in the transient wireless channel conditions and optimize data QoE in a much fastermore expedient way, we advocate the use of the cCross-device/network evaluation methodology. Finally, we presented a few research questions that we are facing and to solicit the research community's input.
【Keywords】: 4G wireless network; end-to-end latency; mobile browsing; quality of user experience (QoE); smart phone; transient state
【Paper Link】 【Pages】:243-246
【Authors】: Udayan Kumar ; Jeeyoung Kim ; Ahmed Helmy
【Abstract】:
【Keywords】: laptop; mobile device; network usage; smart-phone
【Paper Link】 【Pages】:247-250
【Authors】: Ayon Chakraborty ; Samir R. Das ; Milind M. Buddhikot
【Abstract】:
In this paper, we envision a scenario where mobile devices perform at least part-time spectrum sensing in a collaborative fashion under the control of a central server. The goal is to create an adequate radio environment map' for thewhite spaces' that will be useful for spectrum management decisions. We lay out the research challenges, describe a prototype implementation using a DTV receiver dongle interfaced with an Android-based mobile device, and present preliminary performance measurements.
【Keywords】: TV whitespace; radio environment map; spectrum sensing
【Paper Link】 【Pages】:251-254
【Authors】: Tan Zhang ; Suman Banerjee
【Abstract】: The recently released TV whitespaces offer a promising land for wireless communications. The secondary users of TV whitespaces today rely on spectrum occupancy databases to determine vacant TV channels for unlicensed communications. However, the accuracy of these databases (that depend solely on propagation models as per guidelines of the FCC) may be low. In this paper, we propose V-Scope - a vehicular sensing framework aimed to collect wide-area spectrum measurements for evaluating the accuracy of these databases. A key design feature of V-Scope is to leverage spectrum sensors mounted on public vehicles for collecting and reporting measurements from the road (opportunistic wardriving). We have currently deployed a version of our system on a single public transit bus traveling across a mid-sized city in the US. Based on measurements collected at over 1 million locations across a 100 square-km area, we find that databases tend to over-predict the coverage of certain TV broadcasts, unnecessarily blocking the usage of whitespace spectrum in a large area (up to 42% measured locations). We further propose ways of leveraging these measurements to enhance existing propagation models in databases.
【Keywords】: TV whitespaces; opportunistic wardriving; spectrum sensing
【Paper Link】 【Pages】:255-266
【Authors】: Xuhang Ying ; Jincheng Zhang ; Lichao Yan ; Guanglin Zhang ; Minghua Chen ; Ranveer Chandra
【Abstract】: It is a promising vision to utilize white spaces, i.e., vacant VHF and UHF TV channels, to satisfy skyrocketing wireless data demand in both outdoor and indoor scenarios. While most prior works have focused on exploring outdoor white spaces, the indoor story is largely open for investigation. Motivated by this observation and that 70% of the spectrum demand comes from indoor environments, we carry out a comprehensive study of exploring indoor white spaces. We first present a large-scale measurement of outdoor and indoor TV spectrum occupancy in 30+ diverse locations in a typical metropolis Hong Kong. Our measurement results confirm abundant white spaces available for exploration in a wide range of areas in metropolises. In particular, more than 50% and 70% of the TV spectrum are white spaces in outdoor and indoor scenarios, respectively. While there are substantially more white spaces in indoor scenarios than in outdoor scenarios, there is no effective solution for identifying indoor white spaces. To fill in this gap, we propose the first system WISER (for White-space Indoor Spectrum EnhanceR), to identify and track indoor white spaces in a building, without requiring user devices to sense the spectrum. We discuss the design space of such system and justify our design choices using intensive real-world measurements. We design the architecture and algorithms to address the inherent challenges. We build a WISER prototype and carry out real-world experiments to evaluate its performance. Our results show that WISER can identify 30%-50% more indoor white spaces with negligible false alarms, as compared to alternative baseline approaches.
【Keywords】: TV white spaces; clustering algorithms; sensor placement
【Paper Link】 【Pages】:267-278
【Authors】: Souvik Sen ; Bozidar Radunovic ; Jeongkeun Lee ; Kyu-Han Kim
【Abstract】: Wireless performance depends directly on the quality of the channel. A wireless transmitter can improve its performance by estimating and transmitting on only the strongest channel, which can be of significantly higher quality than a weak channel (yielding up to 100% rate improvement). It is considered impossible to predict the quality of the unseen channels. Thus, the only way to identify the strongest channel is by probing each channel individually, incurring large over- heads. The key contribution of this paper is a discovery of previously unobserved properties of the wireless channel that makes it possible to predict the the strongest of a set of channels from the measurements collected only on a single channel. We confirm the properties through measurements and present a theoretical analysis that explains their nature. Our proposed system, CSpy, utilizes these observations to predict the strongest channel. CSpy is the first to reliably estimate the strongest channel by utilizing channel responses extracted from off-the-shelf wireless chipsets, without probing any additional channels. By tracking the strongest channel, CSpy improves performance by up to 100% in comparison to channel agnostic schemes.
【Keywords】: channel estimation; cross-layer; wireless
【Paper Link】 【Pages】:279-290
【Authors】: Fadel Adib ; Swarun Kumar ; Omid Aryan ; Shyamnath Gollakota ; Dina Katabi
【Abstract】: Recent years have witnessed increasing interest in interference alignment which has been demonstrated to deliver gains for wireless networks both analytically and empirically. Typically, interference alignment is achieved by having a MIMO sender precode its transmission to align it at the receiver. In this paper, we show, for the first time, that interference alignment can be achieved via motion, and works even for single-antenna transmitters. Specifically, this alignment can be achieved purely by sliding the receiver's antenna. Interestingly, the amount of antenna displacement is of the order of one inch which makes it practical to incorporate into recent sliding antennas available on the market. We implemented our design on USRPs and demonstrated that it can deliver 1.98× throughput gains over 802.11n in networks with both single-antenna and multi- antenna nodes.
【Keywords】: MIMO; interference alignment; interference nulling; motion-based interference management; sliding antennas; wireless
【Paper Link】 【Pages】:291-302
【Authors】: Binbin Chen ; Ziling Zhou ; Haifeng Yu
【Abstract】: Counting the number of RFID tags, or RFID counting, is needed by a wide array of important wireless applications. Motivated by its paramount practical importance, researchers have developed an impressive arsenal of techniques to improve the performance of RFID counting (i.e., to reduce the time needed to do the counting). This paper aims to gain deeper and fundamental insights in this subject to facilitate future research on this topic. As our central thesis, we find out that the overlooked key design aspect for RFID counting protocols to achieve near-optimal performance is a conceptual separation of a protocol into two phases. The first phase uses small overhead to obtain a rough estimate, and the second phase uses the rough estimate to further achieve an accuracy target. Our thesis also indicates that other performance-enhancing techniques or ideas proposed in the literature are only of secondary importance. Guided by our central thesis, we manage to design near-optimal protocols that are more efficient than existing ones and simultaneously simpler than most of them.
【Keywords】: RFID; RFID counting protocols; counting; lower bounds; two-phase
【Paper Link】 【Pages】:303-314
【Authors】: Federica Bogo ; Enoch Peserico
【Abstract】: This work studies delay and throughput achievable in delay-tolerant networks with ballistic mobility -- informally, when the average distance a node travels before changing direction does not become vanishingly small as the number of nodes in the deployment area grows. Ballistic mobility is a simple condition satisfied by a large number of well-studied mobility models, including the i.i.d. model, the random waypoint model, the uniform mobility model and Levy walks with exponent less than 1. Our contribution is twofold. First, we show that, under some very mild and natural hypotheses satisfied by all models in the literature, ballistic mobility is strictly necessary to achieve simultaneously, as the number of nodes grows, a) per-node throughput that does not become vanishingly small and b) communication delay that does not become infinitely large. Any network whose nodes exhibit a more "local" mobility pattern (e.g. Levy walks with exponent greater than 1, or Brownian motion) must sacrifice either a) or b), regardless of the communication scheme adopted -- even with network coding. Second, we present a novel packet routing scheme. Our scheme is relatively simple and does not rely on centralized control, replication, or static base stations. At the same time it achieves both non-vanishing throughput and bounded delay as the number of nodes grows, on any network with ballistic mobility (i.e. whenever they can be simultaneously achieved), asymptotically outperforming any existing communication scheme that exploits node mobility to boost throughput.
【Keywords】: delay-tolerant networks; in-flight communication; interference; mobile networks; mobility models; network coding; omnidirectional antennas; opportunistic networks; routing; throughput
【Paper Link】 【Pages】:315-326
【Authors】: Shu Liu ; Aaron Striegel
【Abstract】: Wireless network providers are under tremendous pressure to deliver unprecedented amounts of data to a variety of mobile devices. A powerful concept that has only gained limited traction in practice has been the concept of opportunistic networks whereby nodes opportunistically communicate with each other when in range to augment or overcome existing wireless systems. One of the key impediments towards the adoption of opportunistic communications has been the inability to demonstrate viability at scale, namely showing that sufficient opportunities exist and more importantly exist when needed to offer significant network performance gains. We demonstrate through a large-scale, longitudinal study of smartphone users that significant opportunities are indeed prevalent, are indeed stable, and end up being reasonably reciprocal both on short and long-term timescales. In this paper, we propose a framework dubbed PSR (Prevalence, Stability, Reciprocity) to capture key aspects that characterize the net potential for opportunistic networks which we feel merit significantly increased attention.
【Keywords】: bluetooth; opportunistic networks; proximity; relay; wifi
【Paper Link】 【Pages】:327-338
【Authors】: Sangki Yun ; Daehyeok Kim ; Lili Qiu
【Abstract】: Explosive growth of WiFi traffic calls for new technologies to dramatically improve spectrum efficiency. In this paper, we propose an approach to adapt the spectrum on a per-frame basis. It consists of three major components: (i) a fine-grained spectrum access design that allows a sender and receiver to change their transmission and reception spectrum on demand, (ii) fast and accurate spectrum detection that allows a receiver to determine which spectrum is used by its sender on a per-frame basis by exploiting the IEEE 802.11 preamble structure, and (iii) an efficient spectrum allocation algorithm that determines which spectrum to use for each transmission by taking into account frequency diversity and interference. It can further be adapted to perform a joint assignment of spectrum, schedule, and access point (AP) for each frame. Using a SORA implementation and trace-driven simulation, we demonstrate the feasibility of per-frame spectrum adaptation and its significant benefit over existing channel assignment approaches. To our knowledge, this is the first per-frame spectrum adaptation prototype for WiFi networks.
【Keywords】: IEEE 802.11; dynamic spectrum access; physical layer; spectrum allocation
【Paper Link】 【Pages】:339-350
【Authors】: Ashish Patro ; Srinivas Govindan ; Suman Banerjee
【Abstract】: We present a measurement study of wireless experience in a diverse set of home environments by deploying an infrastructure, we call WiSe. Our infrastructure consists of OpenWrt-based Access Points (APs) that have been given away to residents for free to be installed as their primary wireless access mechanism. These APs are configured with our specialized measurement and monitoring software that communicates with our measurement controller through an open API. We have collected wireless performance traces from 30 homes for a period in excess of 6 months. To analyze the characteristics of these home wireless environments, we have also developed a simple metric that estimates the likely TCP throughput different clients can expect based on current channel and environmental conditions. With this infrastructure, we provide multiple quantitative observations, some of which are anecdotally understood in our community. For example, while a majority of links performed well most of the time, we observed cases of poor client experience about 2.1% of the total time.
【Keywords】: characterization; deployment; home WiFi networks; interference; measurement; wise
【Paper Link】 【Pages】:351-362
【Authors】: Tarun Bansal ; Bo Chen ; Prasun Sinha ; Kannan Srinivasan
【Abstract】: In this paper, we propose Symphony, a packet recovery architecture that encourages collisions among transmitters, and utilizes the unused capacity in the backbone to transmit recovered data packets and coordinate the efficient recovery of collided packets. Symphony improves the wireless throughput while incurring a low overhead on the typically under-utilized wired backbone. In Symphony, upon receiving the collided transmissions, the APs carefully suppress a subset of the transmissions. Realizing this idea in practice entails several challenges including identification of clients that have data to transmit and ensuring that the algorithm works despite imperfect time-synchronization and non-zero latency among APs. We present Symphony that addresses these challenges and show how it leverages Successive Interference Cancellation (SIC) to further increase the network throughput. Experiments performed on an USRP testbed shows that on an average, Symphony provides 43% and 187% higher throughput over Omniscient TDMA and IEEE 802.11, respectively. ns-3 based simulation results show that on an average, Symphony provides a throughput of up to 1.63x compared to omniscient TDMA and 5.6x compared to IEEE 802.11.
【Keywords】: cooperative decoding; wireless networks
【Paper Link】 【Pages】:363-368
【Authors】: Krishna Sekar
【Abstract】: In spite of significant advances in the development of low-power designs and power management techniques, power remains and will remain a first-class design constraint for mobile devices. The functionality integrated into mobile devices will only continue to grow with the increasing transition from PCs to super-phones. Power remains one of the critical hurdles to this transition, and without continued innovations in power management, the term "mobile" devices will be rendered moot. In addition to (and closely related to) power challenges in mobile devices are thermal challenges. Increasingly complex and rich functionality in mobile devices leads to higher power dissipation, and consequently, higher temperatures. However, thermal constraints are constant across successive device generations. Thermal limits, even more than power, will become the fundamental bottleneck to increasing the capabilities of such devices, making thermal management techniques crucial. This paper discusses some of the major challenges in power management and thermal management for current and next-generation mobile devices from a semiconductor industry perspective. Specifically, this paper discusses challenges in three areas: process-variability-aware power management, thermally aware power management and thermal management for mobile devices. Broadcom mobile chipsets feature multiple such advanced power and thermal management techniques, with active on-going research and development in each of these areas.
【Keywords】: leakage power; mobile devices; power management; process variability; thermal management
【Paper Link】 【Pages】:369-374
【Authors】: Milind M. Buddhikot
【Abstract】: In this paper, we make a case for future wireless networks that will seamlessly exploit many variable grade spectrum bands. The transformation we envision will be fueled by a fundamental change in the way networks use spectrum. The mix of spectrum options will include existing exclusively licensed and unlicensed bands and new shared spectrum bands where incumbent primary transmitters with interruptible, exclusive access share the band with cooperating (secondary) users. Such bands used in small cell deployments will be key to creating enormous wireless capacity needed to support future traffic demands. The nascent spectrum database technologies will morph into more dynamic spectrum databases and provide essential interference coordination, channel management and monetization. This trend when combined with infrastructure sharing enabled by cloud and SDN technologies will gradually lead to new deployment models. Such network transformation and democratization of spectrum access can fuel innovative business models and new regulatory regimes for wireless networks. We illustrate the new architecture and component radio, database and security technologies using concrete example of incorporating shared spectrum in a small cell network.
【Keywords】: future wireless networks; high capacity wireless; shared spectrum; spectrum databases
【Paper Link】 【Pages】:375-376
【Authors】: Marco Gruteser
【Abstract】: Indoor navigation and location tracking have been popular academic research topics in our community for more than a decade. This has lead to a vast amount of theoretical results, positioning techniques, and system prototypes that were developed in academia and industry research labs for efficient and accurate indoor localization and navigation. Marketplace adoption, however, has been slow -- products have largely focused on outdoor positioning and navigation. Only recently has the industry buzz and investment in indoor positioning and navigation products picked up. This panel will discuss whether indoor positioning solutions are finally ready for the marketplace. It will examine the limitations of the state of the art along dimensions such as precision, accuracy, energy consumption, complexity, and privacy and will debate in which areas, if any, further academic research is called for. The panelists will also discuss why adoption has been slow, whether any significant non-technical hurdles remain, and speculate which technical solutions are most likely to succeed.
【Keywords】: indoor positioning; localization
【Paper Link】 【Pages】:377-388
【Authors】: Mohammad Ashraful Hoque ; Matti Siekkinen ; Jukka K. Nurminen
【Abstract】: Video streaming on smartphones is one of the most popular but also most energy hungry services today. Using mobile video services results in two contradictory sources of energy waste for smartphones: i) energy waste because of excessively aggressive prefetching of content that the user will not watch because of abandoning the session, and ii) excessive amount of tail energy, which is energy wasted by keeping the wireless interface powered on after receiving a chunk of content; this is caused by prefetching chunks that are too small. To remedy this, we propose a novel download scheduling algorithm based on crowd-sourced video viewing statistics. Our algorithm judiciously evaluates the probability of a user interrupting a video viewing in order to perform the right amount of prefetching. In this way, the algorithm balances the amount of the two above-mentioned kinds of energy waste. By simulations, we show that our scheduler cuts the energy waste to half compared to existing download strategies. We have also developed an Android prototype that implements the download scheduler together with a novel downloader that speeds up the download by exploiting the Fast Start technique. The prototype exhibits the desired properties of the scheduler, and its faster downloading mechanism yields further energy savings of up to 80% compared to the default Android YouTube app.
【Keywords】: audience retention; dash; energy saving; mobile multimedia; tail energy
【Paper Link】 【Pages】:389-400
【Authors】: Jiasi Chen ; Rajesh Mahindra ; Amir Khojastepour ; Sampath Rangarajan ; Mung Chiang
【Abstract】: As the growth of mobile video traffic outpaces that of cellular network speed, industry is adopting HTTP-based adaptive video streaming technology which enables dynamic adaptation of video bit-rates to match changing network conditions. However, recent measurement studies have observed problems in fairness, stability, and efficiency of resource utilization when multiple adaptive video flows compete for bandwidth on a shared wired link. Through experiments and simulations, we confirm that such undesirable behavior manifests itself in cellular networks as well. To overcome these problems, we design an in-network resource management framework, AVIS, that schedules HTTP-based adaptive video flows on cellular networks. AVIS effectively manages the resources of a cellular base station across adaptive video flows. AVIS also provides a framework for mobile operators to achieve a desired balance between optimal resource allocation and user quality of experience. AVIS has three key differentiating features: (1) It optimally computes the bit-rate allocation for each user, (2) It includes a scheduler and per-flow shapers to enforce bit-rate stability of each flow and (3) It leverages the resource virtualization technique to separate resource management of adaptive video flows from regular video flows. We implement a prototype system of AVIS and evaluate it on both a WiMAX network testbed and a LTE system simulator to show its efficacy and scalability.
【Keywords】: QoE; adaptive streaming; cellular networks; proportional fairness
【Paper Link】 【Pages】:401-412
【Authors】: Shan-Hsiang Shen ; Aditya Akella
【Abstract】: Recent years have seen a tremendous growth in the volume of video traffic in mobile settings. In this paper, we present the design of a mobile video-centric proxy cache, named iProxy, that offers improved performance in terms of both hit rates and streaming quality. Our thesis in designing iProxy is that we need to elevate the traditional view of caching from "data" to "information" in order to optimally meet the stringent requirements of video streaming in mobile settings. iProxy relies on recent advances on information-bound references (IBRs) to collapse multiple related cache entries into a single one, improving hitrate while lowering storage costs. iProxy incorporates a novel dynamic linear rate adaptation scheme to ensure high stream quality in face of channel diversity and device heterogeneity. Our evaluation of iProxy using realistic traffic traces shows that it can improve hitrate, but we need to use novel information-aware replacement policies for optimal performance. We show that our linear encoder can adapt well to changes in bandwidth, and yield better bit rates, lower buffering and lower start up delays than state-of-the-art schemes.
【Keywords】: caching; quality of experience; video; wireless networks
【Paper Link】 【Pages】:413-414
【Authors】: Thyagarajan Nandagopal
【Abstract】: As wireless technology has progressed from the simple GPRS-based cellular radio modems to the highly complex LTE and 802.11ac networks, users have increasingly sought a satisfactory user experience from video applications running over such networks. This panel discussion aims to look back at the progress made in this aspect, and provide guidance to researchers as to what trends to expect in improving user experience of video consumption over wireless networks.
【Keywords】: broadcast; multicast; video applications; wireless video
【Paper Link】 【Pages】:415-416
【Authors】: Henry Tirri
【Abstract】: In this presentation, Dr. Henry Tirri, EVP & CTO of Nokia and UC Berkeley will discuss insights into the social and scientific implications of the technology trends being driven by the rise of large scale multi-device cloud-based computing. The cloud has already fundamentally transformed everyday experiences visible to consumers through their access to streaming media, social networking and location services via multiple different computing devices, from phones and tablets to connected accessories. As bits continue to eat atoms, more elements of the physical world will turn first into code and then into code that lives in the cloud. This is driven by the enormous advantages in sharing, indexing and elasticity of computing code has with respect to physical objects. We have seen this happening to photos and videos, music and books, but this is only the beginning. Consumers will increasingly turn to connected experiences that will in turn produce a wealth of data at a at rate unprecedented in the history of mankind. Due to the pervasiveness of this change, the next phase of the cloud era will see increased partnerships between public and private sectors around long-term technology trends in areas ranging from urban planning to health care. It can be anticipated that connected hardware will continue to diversify, with an increased emphasis on "multi-sensing". Wearables, sensor clusters in vehicles and smart devices, and independent sensors will all become first class citizens of the cloud: both feeding data into it and drawing it back out again. We will look at one exciting example of this trend -- indexing of the real world made possible by global scale location services. We argue that ultimately computing will totally de-centralize and live throughout a heterogeneous cloud-based architecture, but energy will continue to be the "One Ring to Rule Them All," that will define where in the cloud the execution happens.
【Keywords】: cloud; data; health; infrastructure; location; mapping; mobility; sensing
【Paper Link】 【Pages】:417-428
【Authors】: Michael Farb ; Yue-Hsun Lin ; Tiffany Hyun-Jin Kim ; Jonathan M. McCune ; Adrian Perrig
【Abstract】: Users regularly experience a crisis of confidence on the Internet. Is that email or instant message truly originating from the claimed individual? Such doubts are commonly resolved through a leap of faith, expressing the desperation and helplessness of users. To establish a secure basis for online communication, we propose SafeSlinger, a system leveraging the proliferation of smartphones to enable people to securely and privately exchange their public keys. Through the exchanged authentic public keys, SafeSlinger establishes a secure channel offering secrecy and authenticity, which we use to support secure messaging and file exchange. SafeSlinger also provides an API for importing applications' public keys into a user's contact information. By slinging entire contact entries to others, we propose secure introductions, as the contact entry includes the SafeSlinger public keys as well as other public keys that were imported. We present the design and implementation of SafeSlinger for Android and iOS, which is available from the respective app stores. An overview video of SafeSlinger is available at: http://www.youtube.com/watch?v=IFXL8fUqNKY
【Keywords】: secure communication; security & privacy; trust establishment
【Paper Link】 【Pages】:429-440
【Authors】: Katerina J. Argyraki ; Suhas N. Diggavi ; Melissa Duarte ; Christina Fragouli ; Marios Gatzianas ; Panagiotis Kostopoulos
【Abstract】: Current security systems often rely on the adversary's computational limitations. Wireless networks offer the opportunity for a different, complementary kind of security, which relies on the adversary's limited network presence (i.e., that the adversary cannot be located at many different points in the network at the same time). We present a system that leverages this opportunity to enable n wireless nodes to create a shared secret S, in a way that an eavesdropper, Eve, obtains very little information on S. Our system consists of two steps: (1) The nodes transmit packets following a special pattern, such that Eve learns very little about a given fraction of the transmitted packets. This is achieved through a combination of beam forming (from many different sources) and wiretap codes. (2) The nodes participate in a protocol that reshuffles the information known to each node, such that the nodes end up sharing a secret that Eve knows very little about. Our protocol is easily implementable in existing wireless devices and scales well with the number of nodes; these properties are achieved through a combination of public feedback, broadcasting, and network coding. We evaluate our system through a 5-node testbed. We demonstrate that a group of wireless nodes can generate thousands of new shared secret bits per second, with their secrecy being independent of the adversary's computational capabilities.
【Keywords】: group secret agreement; physical-layer security
【Paper Link】 【Pages】:441-452
【Authors】: Jie Xiong ; Kyle Jamieson
【Abstract】: Despite the important role that WiFi networks play in home and enterprise networks they are relatively weak from a security standpoint. With easily available directional antennas, attackers can be physically located off-site, yet compromise WiFi security protocols such as WEP, WPA, and even to some extent WPA2 through a range of exploits specific to those protocols, or simply by running dictionary and human-factors attacks on users' poorly-chosen passwords. This presents a security risk to the entire home or enterprise network. To mitigate this ongoing problem, we propose SecureArray, a system designed to operate alongside existing wireless security protocols, adding defense in depth against active attacks. SecureArray's novel signal processing techniques leverage multi-antenna access point (AP) to profile the directions at which a client's signals arrive, using this angle-of-arrival (AoA) information to construct highly sensitive signatures that with very high probability uniquely identify each client. Upon overhearing a suspicious transmission, the client and AP initiate an AoA signature-based challenge-response protocol to confirm and mitigate the threat. We also discuss how SecureArray can mitigate direct denial-of-service attacks on the latest 802.11 wireless security protocol. We have implemented SecureArray with an eight-antenna WARP hardware radio acting as the AP. Our experimental results show that in a busy office environment, SecureArray is orders of magnitude more accurate than current techniques, mitigating 100% of WiFi spoofing attack attempts while at the same time triggering false alarms on just 0.6% of legitimate traffic. Detection rate remains high when the attacker is located only five centimeters away from the legitimate client, for AP with fewer numbers of antennas and when client is mobile.
【Keywords】: 802.11; AOA signature; antenna array system; securearray; security; wireless
【Paper Link】 【Pages】:453-464
【Authors】: Xinyu Zhang ; Karthikeyan Sundaresan ; Mohammad Ali Khojastepour ; Sampath Rangarajan ; Kang G. Shin
【Abstract】: Network MIMO (netMIMO) has potential for significantly enhancing the capacity of wireless networks with tight coordination of access points (APs) to serve multiple users concurrently. Existing schemes realize netMIMO by integrating distributed APs into one ``giant'' MIMO but do not scale well owing to their global synchronization requirement and overhead in sharing data between APs. To remedy this limitation, we propose a novel system, NEMOx, that realizes netMIMO downlink transmission for large-scale wireless networks. NEMOx organizes a network into practical-size clusters, each containing multiple distributed APs (dAPs) that opportunistically synchronize with each other for netMIMO downlink transmission. Inter-cluster interference is managed with a decentralized channel-access algorithm, which is designed to balance between the dAPs' cooperation gain and spatial reuse---a unique tradeoff in netMIMO. Within each cluster, NEMOx optimizes the power budgeting among dAPs and the set of users to serve, ensuring fairness and effective cancellation of cross-talk interference. We have implemented and evaluated a prototype of NEMOx in a software radio testbed, demonstrating its throughput scalability and multiple folds of performance gain over current wireless LAN architecture and alternative netMIMO schemes.
【Keywords】: multi-user MIMO networks; network MIMO
【Paper Link】 【Pages】:465-476
【Authors】: Yubo Yan ; Panlong Yang ; Xiang-Yang Li ; Yue Tao ; Lan Zhang ; Lizhao You
【Abstract】: Recent studies show that WiFi interference has been a major problem for low power urban sensing technology ZigBee networks. Existing approaches for dealing with such interferences often modify either the ZigBee nodes or WiFi nodes. However, massive deployment of ZigBee nodes and uncooperative WiFi users call for innovative cross-technology coexistence without intervening legacy systems. In this work we investigate the WiFi and ZigBee coexistence when ZigBee is the interested signal.Mitigating short duration WiFi interference (called flash) in long duration ZigBee data (called smog) is challenging, especially when we cannot modify the WiFi APs and the massively deployed sensor nodes. To address these challenges, we propose ZIMO, a sink-based MIMO design for harmony coexistence of ZigBee and WiFi networks with the goal of protecting the ZigBee data packets.The key insight of ZIMO is to properly exploit opportunities resulted from differences between WiFi and ZigBee, and bridge the gap between interested data and cross technology signals. Also, extracting the channel coefficient of WiFi and ZigBee will enhance other coexistence technologies such as TIMO [1]. We implement a prototype for ZIMO in GNURadio-USRP N200, and our extensive evaluations under real wireless conditions show that ZIMO can improve up to 1.9x throughput for ZigBee network, with median gain of 1.5x, and 1.1x to 1.9x for WiFi network as byproduct in ZigBee signal recovery.
【Keywords】: MIMO; physical layer; sensor networks
【Paper Link】 【Pages】:477-488
【Authors】: Xiufeng Xie ; Xinyu Zhang ; Karthikeyan Sundaresan
【Abstract】: MIMO beamforming technology can scale wireless data rate proportionally with the number of antennas. However, the overhead induced by receivers' CSI (channel state information) feedback scales at a higher rate. In this paper, we address this fundamental tradeoff with Adaptive Feedback Compression (AFC). AFC quantizes or compresses CSI from 3 dimensions --- time, frequency and numerical values, and adapts the intensity of compression according to channel profile. This simple principle faces many practical challenges, e.g., a huge search space for adaption, estimation or prediction of the impact of compression on network throughput, and the coupling of different users in multi-user MIMO networks. AFC meets these challenges using a novel cross-layer adaptation metric, a metric extracted from 802.11 packet preambles, and uses it to guide the selection of compression intensity, so as to balance the tradeoff between overhead reduction and capacity loss (due to compression). We have implemented AFC on a software radio testbed. Our experiments show that AFC can outperform alternative approaches in a variety of radio environments.
【Keywords】: feedback compression; limited feedback; multi-user MIMO networks