The 18th Annual International Conference on Mobile Computing and Networking, Mobicom'12, Istanbul, Turkey, August 22-26, 2012. ACM 【DBLP Link】
【Paper Link】 【Pages】:1-2
【Authors】: Ian F. Akyildiz
【Abstract】: Nanotechnology is enabling the development of devices in a scale ranging from one to a few one hundred nanometers. Nanonetworks, i.e., the interconnection of nano-scale devices, are expected to expand the capabilities of single nano-machines by allowing them to cooperate and share information. Traditional communication technologies are not directly suitable for nanonetworks mainly due to the size and power consumption of existing transmitters, receivers and additional processing components. All these define a new communication paradigm that demands novel solutions such as nano-transceivers, channel models for the nano-scale, and protocols and architectures for nanonetworks. In this talk, first the state-of-the-art in nano-machines, including architectural aspects, expected features of future nano-machines, and current developments are presented for a better understanding of the nanonetwork scenarios. Moreover, nanonetworks features and components are explained and compared with traditional communication networks. Novel nano-antennas based on nano-materials as well as the terahertz band are investigated for electromagnetic communication in nanonetworks. Furthermore, molecular communication mechanisms are presented for short-range networking based on ion signaling and molecular motors, for medium-range networking based on flagellated bacteria and nanorods, as well as for long-range networking based on pheromones and capillaries. Finally, open research challenges such as the development of network components, molecular communication theory, and new architectures and protocols, which need to be solved in order to pave the way for the development and deployment of nanonetworks within the next couple of decades are presented.
【Keywords】: nano-machines; nano-scale devices; nanonetworks
【Paper Link】 【Pages】:3-4
【Authors】: P. R. Kumar
【Abstract】: We propose three theories, which can be regarded as attempts to characterize and establish guaranteed properties of wireless networks: (i) How and to what extent can we deliver packets with hard delay bounds? (ii) How and to what extent can we synchronize clocks in wireless networks? (iii) Can we develop provably secure protocols for the entire life-cycle of wireless networks that also optimize a utility measure while operating in a hostile environment? For the first problem, consider an access point serving several clients over unreliable wireless links. Suppose packets arrive for/from the clients, with each packet having a hard deadline, after which it is dropped. We characterize precisely the mix of delivery ratios, channel unreliabilities and hard deadline that the access point can guarantee, under some models. For the second problem, consider a wireless network where clocks at the nodes are linear, though with different rates (skews) and offsets. Nodes can exchange packets with their neighbors, with direction dependent delays. We characterize precisely to what extent clocks can and cannot be synchronized and delays determined. Under a random model the end-to-end error can be kept bounded irrespective of network size. Concerning the third problem, traditionally, wireless protocols have been developed to provide performance. As attacks are identified, the protocols are fortified against the identified vulnerabilities. However, holistic guarantees are not provided against other attacks. We seek to reverse this paradigm. We propose a provable approach that guarantees the protocol suite is secure when the nodes are subject to certain assumptions. The protocols take a set of good nodes mingled with unknown malicious nodes from primordial birth to an operating network, while attaining min-max of a utility function. The maximization is over protocols announced and followed by the good nodes, and the minimization is over all behaviors of the malicious nodes. Further, the malicious nodes are reduced to either cooperating or jamming. [Joint work with Vivek Borkar, Nikolaos Freris, Scott Graham, I-Hong Hou, Yih-Chun Hu, Jonathan Ponniah and Roberto Solis].
【Keywords】: clock synchronization; delay bounds; security; wireless networking
【Paper Link】 【Pages】:5-16
【Authors】: Aditya Gudipati ; Stephanie Pereira ; Sachin Katti
【Abstract】: Current wireless network design is built on the ethos of avoiding interference. In this paper we question this long-held design principle. We show that with appropriate design, successful concurrent transmissions can be enabled and exploited on both the uplink and downlink. We show that this counter-intuitive approach of encouraging interference can be exploited to increase network capacity significantly and simplify network design. We design and implement name, a novel MAC and PHY protocol that exploits recently proposed rateless coding techniques to provide such concurrency. We show via a prototype implementation and experimental evaluation that name can provide a 60% increase in network capacity on the uplink compared to traditional Wifi that does omniscient rate adaptation and a $35\%$ median throughput gain on the downlink PHY layer as compared to an omniscient scheme that picks the best conventional bitrate.
【Keywords】: MAC protocol; interference exploitation; successive interference cancellation; wireless communication
【Paper Link】 【Pages】:17-28
【Authors】: Peter Anthony Iannucci ; Jonathan Perry ; Hari Balakrishnan ; Devavrat Shah
【Abstract】: Recently, rateless codes have introduced a promising approach to obtaining wireless throughput higher than what is achieved by fixed-rate codes, especially over time-varying channels. Rateless codes like Raptor, Strider, and spinal codes naturally process all the information available at the receiver corresponding to a packet, whether from one or many frame transmissions. However, a profitable deployment of rateless codes in a wireless network requires a link-layer protocol to coordinate between sender and receiver. This protocol needs to determine how much coded data should be sent before the sender pauses for feedback from the receiver. Without such feedback, an open-loop sender would not know when the packet has been decoded, but sending this feedback is not free and consumes a significant fraction of the packet transmission time. This paper develops RateMore, a protocol that learns the probability distribution of the number of symbols required to decode a packet (the decoding CDF), and uses the learned distribution in a dynamic programming strategy to produce an optimal transmission schedule. Our experiments show that RateMore reduces overhead by between 2.6x and 3.9x compared to 802.11-style ARQ and between 2.8x and 5.4x compared to 3GPP-style "Try-after-n" HARQ.
【Keywords】: harq; incremental redundancy; link-layer; protocol; rateless; wireless
【Paper Link】 【Pages】:29-40
【Authors】: Wei-Liang Shen ; Yu-Chih Tung ; Kuang-Che Lee ; Kate Ching-Ju Lin ; Shyamnath Gollakota ; Dina Katabi ; Ming-Syan Chen
【Abstract】: In multiuser MIMO (MU-MIMO) networks, the optimal bit rate of a user is highly dynamic and changes from one packet to the next. This breaks traditional bit rate adaptation algorithms, which rely on recent history to predict the best bit rate for the next packet. To address this problem, we introduce TurboRate, a rate adaptation scheme for MU-MIMO LANs. TurboRate shows that clients in a MU-MIMO LAN can adapt their bit rate on a per-packet basis if each client learns two variables: its SNR when it transmits alone to the access point, and the direction along which its signal is received at the AP. TurboRate also shows that each client can compute these two variables passively without exchanging control frames with the access point. A TurboRate client then annotates its packets with these variables to enable other clients to pick the optimal bit rate and transmit concurrently to the AP. A prototype implementation in USRP-N200 shows that traditional rate adaptation does not deliver the gains of MU-MIMO WLANs, and can interact negatively with MU-MIMO, leading to low throughput. In contrast, enabling MU-MIMO with TurboRate provides a mean throughput gain of 1.7x and 2.3x, for 2-antenna and 3-antenna APs respectively.
【Keywords】: multiuser mimo networks; rate adaptation
【Paper Link】 【Pages】:41-52
【Authors】: Horia Vlad Balan ; Ryan Rogalin ; Antonios Michaloliakos ; Konstantinos Psounis ; Giuseppe Caire
【Abstract】: A distributed MIMO system consists of several access points connected to a central server and operating as a large distributed multi-antenna access point. In theory, such a system enjoys all the significant performance gains of a traditional MIMO system, and it may be deployed in an enterprise WiFi like setup. In this paper, we investigate the efficiency of such a system in practice. Specifically, we build upon our prior work on developing a distributed MIMO testbed, and study the performance of such a system when both full channel state information is available to the transmitters and when no channel state information is available. In the full channel state information scenario, we implement Zero-Forcing Beamforming (ZFBF) and Tomlinson-Harashima Precoding (THP) which is provably near-optimal in high SNR conditions. In the scenario where no channel information is available, we implement Blind Interference Alignment (BIA), which achieves a higher multiplexing gain (degrees of freedom) than conventional TDMA. Our experimental results show that the performance of our implementation is very close to the theoretically predicted performance and offers significant gains over optimal TDMA. We also discuss medium access layer issues in detail for both scenarios. To the best of our knowledge, this is the first time that the theoretical high data rates of multiuser MIMO systems have been showcased in a real world distributed MIMO testbed.
【Keywords】: software radio; synchronization; virtual mimo; wireless
【Paper Link】 【Pages】:53-64
【Authors】: Clayton Shepard ; Hang Yu ; Narendra Anand ; Erran L. Li ; Thomas L. Marzetta ; Yang Richard Yang ; Lin Zhong
【Abstract】: Multi-user multiple-input multiple-output theory predicts manyfold capacity gains by leveraging many antennas on wireless base stations to serve multiple clients simultaneously through multi-user beamforming (MUBF). However, realizing a base station with a large number antennas is non-trivial, and has yet to be achieved in the real-world. We present the design, realization, and evaluation of Argos, the first reported base station architecture that is capable of serving many terminals simultaneously through MUBF with a large number of antennas (M >> 10). Designed for extreme flexibility and scalability, Argos exploits hierarchical and modular design principles, properly partitions baseband processing, and holistically considers real-time requirements of MUBF. Argos employs a novel, completely distributed, beamforming technique, as well as an internal calibration procedure to enable implicit beamforming with channel estimation cost independent of the number of base station antennas. We report an Argos prototype with 64 antennas and capable of serving 15 clients simultaneously. We experimentally demonstrate that by scaling from 1 to 64 antennas the prototype can achieve up to 6.7 fold capacity gains while using a mere 1/64th of the transmission power.
【Keywords】: MRT; beamforming; conjugate; large-scale antenna systems (LSAS); many-antenna; massive MIMO; multi-user MIMO; zero-forcing
【Paper Link】 【Pages】:65-76
【Authors】: Eugenio Magistretti ; Omer Gurewitz ; Edward W. Knightly
【Abstract】: In this paper, we design, implement and evaluate 802.11ec (Encoded Control), an 802.11-based protocol without control messages: instead, 802.11ec employs correlatable symbol sequences, which together with the timing the codes are transmitted, encode all control information and change the fundamental design properties of the MAC. The use of correlatable symbol sequences provides two key advantages: (i) efficiency, as it permits a near order of magnitude reduction of the control time; (ii) robustness, because codes are short and easily detectable even at low SINR and even while a neighbor is transmitting data. We implement 802.11ec on an FPGA-based software defined radio. We perform a large number of experiments and show that, compared to 802.11 (with and without RTS/CTS), 802.11ec achieves a vast efficiency gain in conveying control information and resolves key throughput and fairness problems in the presence of hidden terminals, asymmetric topologies, and general multi-hop topologies.
【Keywords】: 802.11; RTS/CTS; WLANs; channel access; collision avoidance; control messages; signal correlation
【Paper Link】 【Pages】:77-88
【Authors】: Sang-Yoon Chang ; Yih-Chun Hu ; Nicola Laurenti
【Abstract】: In wireless networks, users share a transmission medium. To increase the efficiency of channel usage, wireless systems often use a Medium Access Control (MAC) protocol to perform channel coordination by having each node announce its usage intentions; other nodes avoid making conflicting transmissions minimizing interference both to the node that has announced its intentions and to a node that cooperates by avoiding transmissions during the reserved slot. Traditionally, in a multi-channel environment, such announcements are made on a common control channel. However, this control channel is vulnerable to jamming because its location is pre-assigned and known to attackers. Furthermore, the announcements themselves provide information useful for jamming. In this paper, we focus on a situation where multiple wireless transmitters share spectrum in the presence of intelligent and possibly insider jammers capable of dynamically and adaptively changing their jamming patterns. We develop a framework for effectively countering MAC-aware jamming attacks and then propose SimpleMAC, a protocol resilient to these attacks. SimpleMAC consists of two schemes (the Simple Transmitter Strategy and the Simple Signaling Scheme) that are easily analyzed using game theory, and show the optimal adversarial behavior under these protocols. We evaluate our schemes mathematically, through Monte Carlo simulations, and by implementation on the WARP software-defined radio platform. SimpleMAC provides very rapid improvement over the alternative of not using any MAC protocol, and eventually converges to optimal performance (over six-fold improvement in SINR, 50% gains in Shannon capacity in a realistic mobile scenario).
【Keywords】: MAC-layer; jamming; wireless
【Paper Link】 【Pages】:89-100
【Authors】: Jiansong Zhang ; Haichen Shen ; Kun Tan ; Ranveer Chandra ; Yongguang Zhang ; Qian Zhang
【Abstract】: Retransmissions reduce the efficiency of data communication in wireless networks because of: (i) per-retransmission packet headers, (ii) contention overhead on every retransmission, and (iii) redundant bits in every retransmission. In fact, every retransmission nearly doubles the time to successfully deliver the packet. To improve spectrum efficiency in a lossy environment, we propose a new in-frame retransmission scheme using uACKs. Instead of waiting for the entire transmission to end before sending the ACK, the receiver sends smaller uACKs for every few symbols, on a separate narrow feedback channel. Based on these uACKs, the sender only retransmits the lost symbols after the last data symbol in the frame, thereby adaptively changing the frame size to ensure it is successfully delivered. We have implemented uACK on the Sora platform. Experiments with our prototype validate the feasibility of symbol-level uACK . By significantly reducing the retransmistion overhead, the sender is able to aggressively use higher data rate for a lossy link. Both improve the overall network efficiency. Our experimental results from a controlled environment and an 9-node software radio testbed show that uACK can have up to 140% throughput gain over 802.11g and up to 60% gain over the best known retransmission scheme.
【Keywords】: error recovery; feedback; retransmission; uack; wlan
【Paper Link】 【Pages】:101-112
【Authors】: Pavan K. Athivarapu ; Ranjita Bhagwan ; Saikat Guha ; Vishnu Navda ; Ramachandran Ramjee ; Dushyant Arora ; Venkata N. Padmanabhan ; George Varghese
【Abstract】: Many networked applications that run in the background on a mobile device incur significant energy drains when using the cellular radio interface for communication. This is mainly due to the radio-tail, where the cellular radio remaining in a high energy state for up to 20s after each communication spurt. In order to cut down energy consumption, many recent devices employ fast dormancy, a feature that forces the client radio to quickly go into a low energy state after a fixed short idle period. However, aggressive idle timer values for fast dormancy can increase signaling overhead due to frequent state transitions, which negatively impacts the network. In this work, we have designed and implemented RadioJockey, a system that uses program execution traces to predict the end of communication spurts, thereby accurately invoking fast dormancy without increasing network signaling load. We evaluate RadioJockey on a broad range of background applications and show that it achieves 20-40\% energy savings with negligible increase in signaling overhead compared to fixed idle timer-based approaches.
【Keywords】: 3G; 4G; LTE; cellular; energy saving; fast dormancy; signaling overhead
【Paper Link】 【Pages】:113-124
【Authors】: Chunyi Peng ; Guan-Hua Tu ; Chi-Yu Li ; Songwu Lu
【Abstract】: Data-plan subscribers are charged based on the used traffic volume in 3G/4G cellular networks. This usage-based charging system has been operational and received general success. In this work, we conduct experiments to critically assess both this usage-based accounting architecture and application-specific charging policies by operators. Our evaluation compares the network-recorded volume with the delivered traffic at the end device. We have found that, both generally work in common scenarios but may go wrong in the extreme cases: We are charged for what we never get, and we can get what we want for free. In one extreme case, we are charged for at least three hours and 450MB or more data despite receiving no single bit. In another extreme case, we are able to transfer 200MB or any amount we specify for free. The root causes lie in lack of both coordination between the charging system and the end device, and prudent policy enforcement by certain operators. We propose immediate fixes and discuss possible future directions.
【Keywords】: accounting; cellular networks; charging; mobile data services
【Paper Link】 【Pages】:125-136
【Authors】: Sourjya Bhaumik ; Shoban Preeth Chandrabose ; Manjunath Kashyap Jataprolu ; Gautam Kumar ; Anand Muralidhar ; Paul A. Polakos ; Vikram Srinivasan ; Thomas Woo
【Abstract】: The cellular industry is evaluating architectures to distribute the signal processing in radio access networks. One of the options is to process the signals of all base stations on a shared pool of compute resources in a central location. In this centralized architecture, the existing base stations will be replaced with just the antennas and a few other active RF components, and the remainder of the digital processing including the physical layer will be carried out in a central location. This model has potential benefits that include a reduction in the cost of operating the network due to fewer site visits, easy upgrades, and lower site lease costs, and an improvement in the network performance with joint signal processing techniques that span multiple base stations. Further there is a potential to exploit variations in the processing load across base stations, to pool the base stations into fewer compute resources, thereby allowing the operator to either reduce energy consumption by turning the remaining processors off or reducing costs by provisioning fewer compute resources. We focus on this aspect in this paper. Specifically, we make the following contributions in the paper. Based on real-world data, we characterise the potential savings if shared homogeneous compute resources are used to process the signals from multiple base stations in the centralized architecture. We show that the centralized architecture can potentially result in savings of at least 22 % in compute resources by exploiting the variations in the processing load across base stations. These savings are achievable with statistical guarantees on successfully processing the base station's signals. We also design a framework that has two objectives: (i) partitioning the set of base stations into groups that are simultaneously processed on a shared homogeneous compute platform for a given statistical guarantee, and (ii) scheduling the set of base stations allocated to a platform in order to meet their real-time processing requirements. This partitioning and scheduling framework saves up to 19 % of the compute resources for a probability of failure of one in 100 million. We refer to this solution as CloudIQ. Finally we implement and extensively evaluate the CloudIQ framework with a 3GPP compliant implementation of 5 MHz LTE.
【Keywords】: cellular; cloud-ran; virtualization
【Paper Link】 【Pages】:137-148
【Authors】: Xuetao Wei ; Lorenzo Gomez ; Iulian Neamtiu ; Michalis Faloutsos
【Abstract】: The Android platform lacks tools for assessing and monitoring apps in a systematic way. This lack of tools is particularly problematic when combined with the open nature of Google Play, the main app distribution channel. As our key contribution, we design and implement ProfileDroid, a comprehensive, multi-layer system for monitoring and profiling apps. Our approach is arguably the first to profile apps at four layers: (a) static, or app specification, (b) user interaction, (c) operating system, and (d) network. We evaluate 27 free and paid Android apps and make several observations: (a) we identify discrepancies between the app specification and app execution, (b) free versions of apps could end up costing more than their paid counterparts, due to an order of magnitude increase in traffic, (c) most network traffic is not encrypted, (d) apps communicate with many more sources than users might expect---as many as 13, and (e) we find that 22 out of 27 apps communicate with Google during execution. ProfileDroid is the first step towards a systematic approach for (a) generating cost-effective but comprehensive app profiles, and (b) identifying inconsistencies and surprising behaviors.
【Keywords】: android apps; google android; monitoring; profiling; system
【Paper Link】 【Pages】:149-160
【Authors】: Eugene Chai ; Jeongkeun Lee ; Sung-Ju Lee ; Raúl H. Etkin ; Kang G. Shin
【Abstract】: Spectrum management and device coordination for Dynamic Spectrum Access (DSA) networks have received significant research attention. However, current wireless devices have yet to fully embrace DSA networks due to the difficulties in realizing spectrum-agile communications. We address the practical hurdles and present solutions towards implementing DSA devices, answering an important question "what is a simple practical extension to current wireless devices that makes them spectrum-agile?" To this end, we propose RODIN, a general per-frame spectrum-shaping protocol that has the following features to support DSA in commercial off-the-shelf (COTS) wireless devices: (a) direct manipulation of passband signals from COTS devices, (b) fast FPGA-based spectrum shaping, and (c) a novel preamble design for spectrum agreement. RODIN uses an FPGA-based spectrum shaper together with a preamble I-FOP to achieve per-frame spectrum shaping with a delay of under 10 μ s.
【Keywords】: hybrid radio; per-frame spectrum shaping; software-defined radio; spectrum agility; spectrum-agile preamble detection
【Paper Link】 【Pages】:161-172
【Authors】: Shruti Sanadhya ; Raghupathy Sivakumar ; Kyu-Han Kim ; Paul Congdon ; Sriram Lakshmanan ; Jatinder Pal Singh
【Abstract】: Network deduplication (dedup) is an attractive approach to improve network performance for mobile devices. With traditional deduplication, the dedup~source uses only the portion of the cache at the dedup~destination that it is aware of. We argue in this work that in a mobile environment, the dedup~destination (say the mobile) could have accumulated a much larger cache than what the current dedup~source is aware of. This can occur because of several reasons ranging from the mobile consuming content through heterogeneous wireless technologies, to the mobile moving across different wireless networks. In this context, we propose asymmetric caching, a solution that is overlaid on baseline network deduplication, but which allows the dedup~destination to selectively feedback appropriate portions of its cache to the dedup~source with the intent of improving the redundancy elimination efficiency. We show using traffic traces collected from 30 mobile users, that with asymmetric caching, over 89% of the achievable redundancy can be identified and eliminated even when the dedup~source has less than one hundredth of the cache size as the dedup~destination. Further, we show that the ratio of bytes saved from transmission at the dedup~source because of asymmetric caching is over 6x that of the number of bytes sent as feedback. Finally, with a prototype implementation of asymmetric caching on both a Linux laptop and an Android smartphone, we demonstrate that the solution is deployable with reasonable CPU and memory overheads.
【Keywords】: asymmetric caching; bandwidth conservation; mobile devices; mobile networks; mobile traffic; network deduplication
【Paper Link】 【Pages】:173-184
【Authors】: Dejun Yang ; Guoliang Xue ; Xi Fang ; Jian Tang
【Abstract】: Mobile phone sensing is a new paradigm which takes advantage of the pervasive smartphones to collect and analyze data beyond the scale of what was previously possible. In a mobile phone sensing system, the platform recruits smartphone users to provide sensing service. Existing mobile phone sensing applications and systems lack good incentive mechanisms that can attract more user participation. To address this issue, we design incentive mechanisms for mobile phone sensing. We consider two system models: the platform-centric model where the platform provides a reward shared by participating users, and the user-centric model where users have more control over the payment they will receive. For the platform-centric model, we design an incentive mechanism using a Stackelberg game, where the platform is the leader while the users are the followers. We show how to compute the unique Stackelberg Equilibrium, at which the utility of the platform is maximized, and none of the users can improve its utility by unilaterally deviating from its current strategy. For the user-centric model, we design an auction-based incentive mechanism, which is computationally efficient, individually rational, profitable, and truthful. Through extensive simulations, we evaluate the performance and validate the theoretical properties of our incentive mechanisms.
【Keywords】: crowdsourcing; incentive mechanism design; mobile phone sensing
【Paper Link】 【Pages】:185-196
【Authors】: Mehedi Bakht ; Matt Trower ; Robin Hillary Kravets
【Abstract】: The rapid deployment of millions of mobile sensors and smartphones has resulted in a demand for opportunistic encounter-based networking to support mobile social networking applications and proximity-based gaming. However, the success of these emerging networks is limited by the lack of effective and energy efficient neighbor discovery protocols. While probabilistic approaches perform well for the average case, they exhibit long tails resulting in high upper bounds on neighbor discovery time. Recent deterministic protocols, which allow nodes to wake up at specific timeslots according to a particular pattern, improve on the worst case bound, but do so by sacrificing average case performance. In response to these limitations, we have designed Searchlight, a highly effective asynchronous discovery protocol that is built on three basic ideas. First, it leverages the constant offset between periodic awake slots to design a simple probing-based approach to ensure discovery. Second, it allows awake slots to cover larger sections of time, which ultimately reduces total awake time drastically. Finally, Searchlight has the option to employ probabilistic techniques with its deterministic approach that can considerably improve its performance in the average case when all nodes have the same duty cycle. We validate Searchlight through analysis and real-world experiments on smartphones that show considerable improvement (up to 50%) in worst-case discovery latency over existing approaches in almost all cases, irrespective of duty cycle symmetry.
【Keywords】: ad hoc networks; mobile social networks; neighbor discovery; smartphone
【Paper Link】 【Pages】:197-208
【Authors】: Tam Vu ; Akash Baid ; Simon Gao ; Marco Gruteser ; Richard E. Howard ; Janne Lindqvist ; Predrag Spasojevic ; Jeffrey Walling
【Abstract】: As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for identifying and authenticating users have become cumbersome and time-consuming. In this paper, we present a capacitive communication method through which a device can recognize who is interacting with it. This method exploits the capacitive touchscreens, which are now used in laptops, phones, and tablets, as a signal receiver. The signal that identifies the user can be generated by a small transmitter embedded into a ring, watch, or other artifact carried on the human body. We explore two example system designs with a low-power continuous transmitter that communicates through the skin and a signet ring that needs to be touched to the screen. Experiments with our prototype transmitter and tablet receiver show that capacitive communication through a touchscreen is possible, even without hardware or firmware modifications on a receiver. This latter approach imposes severe limits on the data rate, but the rate is sufficient for differentiating users in multiplayer tablet games or parental control applications. Controlled experiments with a signal generator also indicate that future designs may be able to achieve datarates that are useful for providing less obtrusive authentication with similar assurance as PIN codes or swipe patterns commonly used on smartphones today.
【Keywords】: capacitive touch communication; distinguishing users; signetring; touchscreen communication; user identification
【Paper Link】 【Pages】:209-220
【Authors】: Jongwon Yoon ; Honghai Zhang ; Suman Banerjee ; Sampath Rangarajan
【Abstract】: Although wireless broadband technologies have evolved significantly over the past decade, they are still insufficient to support the fast-growing mobile traffic, especially due to the increasing popularity of mobile video applications. Wireless multicast, aiming to exploit the wireless broadcast advantage, is a viable approach to bridge the gap between the limited wireless networking capacity and the ever-increasing mobile video traffic demand. In this work, we propose MuVi, a Multicast Video delivery scheme in OFDMA-based 4G wireless networks, to optimize multicast video traffic. MuVi differentiates video frames based on their importance in reconstructing the video and incorporates an efficient radio resource allocation algorithm to optimize the overall video quality across all users in the multicast group. MuVi is a lightweight solution with most of the implementation in the gateway, slight modification in the base-station, and no modification at the clients. We implement MuVi on a WiMAX testbed and compare its performance to a Naive wireless multicast scheme that employs the most robust MCS (Modulation and Coding Scheme), and an Adaptive scheme that employs the highest MCS supportable by all clients. Experimental results show that MuVi improves the average video PSNR (Peak Signal-to-Noise Ratio) by up to 13 and 7 dB compared to the Naive and the Adaptive schemes, respectively. MuVi does not require modification to the video encoding scheme or the air interface. Thus it allows speedy deployment in existing systems.
【Keywords】: cellular networks; ofdma; resource management; video multicast
【Paper Link】 【Pages】:221-232
【Authors】: An (Jack) Chan ; Amit Pande ; Eilwoo Baik ; Prasant Mohapatra
【Abstract】: Video quality assessment in mobile devices, for instances smart phones and tablets, raises unique challenges such as unavailability of original videos, the limited computation power of mobile devices and inherent characteristics of wireless networks (packet loss and delay). In this paper, we present a metric, Temporal Variation Metric (TVM), to measure the temporal information of videos. Despite its simplicity, it shows a high correlation coefficient of 0.875 to optical flow which captures all motion information in a video. We use the TVM values to derive a reduced-reference temporal quality assessment metric, Temporal Variation Index (TVI), which quantifies the quality degradation incurred in network transmission. Subjective assessments demonstrate that TVI is a very good predictor of users' Quality of Experience (QoE). Its prediction shows a 92.5% of correlation to subjective Mean Opinion Score (MOS) ratings. Through video streaming experiments, we show that TVI can also estimate the network conditions such as packet loss and delay. It depicts an accuracy of almost 95% in extensive tests on 183 video traces.
【Keywords】: mobile devices; quality of experience; video quality
【Paper Link】 【Pages】:233-244
【Authors】: Xiao Lin Liu ; Wenjun Hu ; Qifan Pu ; Feng Wu ; Yongguang Zhang
【Abstract】: We observe two trends, growing wireless capability at the physical layer powered by MIMO-OFDM, and growing video traffic as the dominant application traffic. Both the source and MIMO-OFDM channel components exhibit non-uniform energy distribution. This motivates us to leverage the source data redundancy at the channel to achieve high video recovery performance. We propose ParCast that first separates the source and channel into independent components, matches the more important source components with higher-gain channel components, allocates power weights with joint consideration to the source and the channel, and uses analog modulation for transmission. Such a scheme achieves fine-grained unequal error protection across source components. We implemented ParCast in Matlab and on Sora. Extensive evaluation shows that our scheme outperforms competitive schemes by notable margins, sometimes up to 5~dB in PSNR for challenging scenarios.
【Keywords】: MIMO-OFDM; joint source-channel design; video
【Paper Link】 【Pages】:245-256
【Authors】: Dong Li ; Tarun Bansal ; Zhixue Lu ; Prasun Sinha
【Abstract】: Access to relative location of nearby vehicles on the local roads or on the freeways is useful for providing critical alerts to the drivers, thereby enhancing their driving experience as well as reducing the chances of accidents. The problem of determining the relative location of two vehicles can be broken into two smaller subproblems: (i) Relative lane localization, where a vehicle determines if the other vehicle is in left lane, same lane or right lane with respect to it, and (ii) Relative front-rear localization where it needs to be determined which of the two vehicles is ahead of the other on the road. In this paper, we propose a novel antenna diversity based solution, MARVEL, that solves the two problems of determining the relative location of two vehicles. MARVEL has two components: (i) a smartphone; and (ii) four wireless radios. Unlike exisiting technologies, MARVEL can also determine relative location of vehicles that are not in the immediate neighborhood, thereby providing the driver with more time to react. Further, due to minimal hardware requirements, the deployment cost of MARVEL is low and it can be easily installed on newer as well as existing vehicles. Using results from our real driving tests, we show that MARVEL is able to determine the relative lane location of two vehicles with 96.8% accuracy. Through trace-driven simulations, we also show that by aggregating information across different vehicles, MARVEL is able to increase the localization accuracy to 98%.
【Keywords】: location classification; smartphone; wireless ranging
【Paper Link】 【Pages】:257-268
【Authors】: Ehsan Aryafar ; Mohammad Ali Khojastepour ; Karthikeyan Sundaresan ; Sampath Rangarajan ; Mung Chiang
【Abstract】: Given that full duplex (FD) and MIMO both employ multiple antenna resources, an important question that arises is how to make the choice between MIMO and FD? We show that optimal performance requires a combination of both to be used. Hence, we present the design and implementation of MIDU, the first MIMO full duplex system for wireless networks. MIDU employs antenna cancellation with symmetric placement of transmit and receive antennas as its primary RF cancellation technique. We show that MIDU's design provides large amounts of self-interference cancellation with several key advantages: (i) It allows for two stages of additive antenna cancellation in tandem, to yield as high as 45 dB self-interference suppression; (ii) It can potentially eliminate the need for other forms of analog cancellation, thereby avoiding the need for variable attenuator and delays; (iii) It easily scales to MIMO systems, therefore enabling the coexistence of MIMO and full duplex. We implemented MIDU on the WARP FPGA platform, and evaluated its performance against half duplex (HD)-MIMO. Our results reveal that, with the same number of RF chains, MIDU can potentially double the throughput achieved by half duplex MIMO in a single link; and provide median gains of at least 20% even in single cell scenarios, where full duplex encounters inter-client interference. Based on key insights from our results, we also highlight how to efficiently enable scheduling for a MIDU node.
【Keywords】: full duplex; multi-user MIMO
【Paper Link】 【Pages】:269-280
【Authors】: Zheng Yang ; Chenshu Wu ; Yunhao Liu
【Abstract】: Indoor localization is of great importance for a range of pervasive applications, attracting many research efforts in the past decades. Most radio-based solutions require a process of site survey, in which radio signatures of an interested area are annotated with their real recorded locations. Site survey involves intensive costs on manpower and time, limiting the applicable buildings of wireless localization worldwide. In this study, we investigate novel sensors integrated in modern mobile phones and leverage user motions to construct the radio map of a floor plan, which is previously obtained only by site survey. On this basis, we design LiFS, an indoor localization system based on off-the-shelf WiFi infrastructure and mobile phones. LiFS is deployed in an office building covering over 1600m2, and its deployment is easy and rapid since little human intervention is needed. In LiFS, the calibration of fingerprints is crowdsourced and automatic. Experiment results show that LiFS achieves comparable location accuracy to previous approaches even without site survey.
【Keywords】: RSS fingerprint; floor plan; indoor localization; site survey; smartphones
【Paper Link】 【Pages】:281-292
【Authors】: Rajalakshmi Nandakumar ; Krishna Kant Chintalapudi ; Venkata N. Padmanabhan
【Abstract】: We consider the problem of locating devices such as laptops, desktops, smartphones etc. within an office environment, without requiring any special hardware or infrastructure. We consider two widely-studied approaches to indoor localization: (a) those based on Radio Frequency (RF) measurements made by devices with WiFi or cellular interfaces, and (b) those based on Acoustic Ranging (AR) measurements made by devices equipped with a speaker and a microphone. A typical office environment today comprises devices that are amenable to either one or both these approaches to localization. In this paper we ask the question, "How can we combine RF and AR based approaches in synergy to locate a wide range of devices, leveraging the benefits of both approaches?" The key contribution of this paper is Centaur, a system that fuses RF and AR based localization techniques into a single systematic framework that is based on Bayesian inference. Centaur is agnostic to the specific RF or AR technique used, giving users the flexibility of choosing their preferred RF or AR schemes. We also make two additional contributions: making AR more robust in non-line-of-sight settings (EchoBeep) and adapting AR to localize speaker-only devices (DeafBeep). We evaluate the performance of our AR enhancements and that of the Centaur framework through microbenchmarks and deployment in an office environment.
【Keywords】: acoustic; localization; wifi
【Paper Link】 【Pages】:293-304
【Authors】: Anshul Rai ; Krishna Kant Chintalapudi ; Venkata N. Padmanabhan ; Rijurekha Sen
【Abstract】: Radio Frequency (RF) fingerprinting, based onWiFi or cellular signals, has been a popular approach to indoor localization. However, its adoption in the real world has been stymied by the need for sitespecific calibration, i.e., the creation of a training data set comprising WiFi measurements at known locations in the space of interest. While efforts have been made to reduce this calibration effort using modeling, the need for measurements from known locations still remains a bottleneck. In this paper, we present Zee -- a system that makes the calibration zero-effort, by enabling training data to be crowdsourced without any explicit effort on the part of users. Zee leverages the inertial sensors (e.g., accelerometer, compass, gyroscope) present in the mobile devices such as smartphones carried by users, to track them as they traverse an indoor environment, while simultaneously performing WiFi scans. Zee is designed to run in the background on a device without requiring any explicit user participation. The only site-specific input that Zee depends on is a map showing the pathways (e.g., hallways) and barriers (e.g., walls). A significant challenge that Zee surmounts is to track users without any a priori, user-specific knowledge such as the user's initial location, stride-length, or phone placement. Zee employs a suite of novel techniques to infer location over time: (a) placement-independent step counting and orientation estimation, (b) augmented particle filtering to simultaneously estimate location and user-specific walk characteristics such as the stride length,(c) back propagation to go back and improve the accuracy of ocalization in the past, and (d) WiFi-based particle initialization to enable faster convergence. We present an evaluation of Zee in a large office building.
【Keywords】: calibration free; indoor; localization; particle filter; wifi
【Paper Link】 【Pages】:305-316
【Authors】: Hongbo Liu ; Yu Gan ; Jie Yang ; Simon Sidhom ; Yan Wang ; Yingying Chen ; Fan Ye
【Abstract】: Highly accurate indoor localization of smartphones is critical to enable novel location based features for users and businesses. In this paper, we first conduct an empirical investigation of the suitability of WiFi localization for this purpose. We find that although reasonable accuracy can be achieved, significant errors (e.g., $6\sim8m$) always exist. The root cause is the existence of distinct locations with similar signatures, which is a fundamental limit of pure WiFi-based methods. Inspired by high densities of smartphones in public spaces, we propose a peer assisted localization approach to eliminate such large errors. It obtains accurate acoustic ranging estimates among peer phones, then maps their locations jointly against WiFi signature map subjecting to ranging constraints. We devise techniques for fast acoustic ranging among multiple phones and build a prototype. Experiments show that it can reduce the maximum and 80-percentile errors to as small as $2m$ and $1m$, in time no longer than the original WiFi scanning, with negligible impact on battery lifetime.
【Keywords】: peer assisted localization; smartphone; wifi fingerprint localization
【Paper Link】 【Pages】:317-328
【Authors】: Radhika Mittal ; Aman Kansal ; Ranveer Chandra
【Abstract】: Battery life is a critical performance and user experience metric on mobile devices. However, it is difficult for app developers to measure the energy used by their apps, and to explore how energy use might change with conditions that vary outside of the developer's control such as network congestion, choice of mobile operator, and user settings for screen brightness. We present an energy emulation tool that allows developers to estimate the energy use for their mobile apps on their development workstation itself. The proposed techniques scale the emulated resources including the processing speed and network characteristics to match the app behavior to that on a real mobile device. We also enable exploring multiple operating conditions that the developers cannot easily reproduce in their lab. The estimation of energy relies on power models for various components, and we also add new power models for components not modeled in prior works such as AMOLED displays. We also present a prototype implementation of this tool and evaluate it through comparisons with real device energy measurements.
【Keywords】: developer tools; display power; energy efficiency
【Paper Link】 【Pages】:329-340
【Authors】: Zhenjiang Li ; Wenwei Chen ; Cheng Li ; Mo Li ; Xiang-Yang Li ; Yunhao Liu
【Abstract】: In this paper, we propose a novel clock calibration approach called FLIGHT, which leverages the fact that the fluorescent light intensity changes with a stable period that equals half of the alternating current's. By tuning to the light emitted from indoor fluorescent lamps, FLIGHT can intelligently extract the light period information and achieve network wide time calibration by referring to such a common time reference. We address a series of practical challenges and implement FLIGHT in TelosB motes. We conduct comprehensive experiments using a 12-node test-bed in both static and mobile environments. Over one-week measurement suggests that compared with existing technologies, FLIGHT can achieve tightly synchronized time with low energy consumption.
【Keywords】: clock calibration; energy efficiency; fluorescent lighting
【Paper Link】 【Pages】:341-352
【Authors】: Chi-Yu Li ; Chunyi Peng ; Songwu Lu ; Xinbing Wang
【Abstract】: Rate adaptation (RA) has been used to achieve high goodput. In this work, we explore to use RA for energy efficiency in 802.11n NICs. We show that current MIMO RA algorithms are not energy efficient for NICs despite ensuring high throughput. The fundamental problem is that, the high-throughput setting is not equivalent to the energy-efficient one. Marginal throughput gain may be realized at high energy cost. We propose EERA, an energy-based RA solution that trades off goodput for energy savings at NICs. Our experiments have confirmed its energy savings at NICs while keeping the cost at the device level and across clients acceptable.
【Keywords】: IEEE 802.11n; MIMO; energy efficiency; rate adaptation
【Paper Link】 【Pages】:353-364
【Authors】: Haitham Hassanieh ; Fadel Adib ; Dina Katabi ; Piotr Indyk
【Abstract】: GPS is one of the most widely used wireless systems. A GPS receiver has to lock on the satellite signals to calculate its position. The process of locking on the satellites is quite costly and requires hundreds of millions of hardware multiplications, leading to high power consumption. The fastest known algorithm for this problem is based on the Fourier transform and has a complexity of O(n log n), where n is the number of signal samples. This paper presents the fastest GPS locking algorithm to date. The algorithm reduces the locking complexity to O(n√(log n)). Further, if the SNR is above a threshold, the algorithm becomes linear, i.e., O(n). Our algorithm builds on recent developments in the growing area of sparse recovery. It exploits the sparse nature of the synchronization problem, where only the correct alignment between the received GPS signal and the satellite code causes their cross-correlation to spike. We further show that the theoretical gain translates into empirical gains for GPS receivers. Specifically, we built a prototype of the design using software radios and tested it on two GPS data sets collected in the US and Europe. The results show that the new algorithm reduces the median number of multiplications by 2.2x in comparison to the state of the art design, for real GPS signals.
【Keywords】: GPS; sparse fourier transform; synchronization
【Paper Link】 【Pages】:365-376
【Authors】: Muhammad Shahzad ; Alex X. Liu
【Abstract】: Radio Frequency Identification (RFID) systems have been widely deployed for various applications such as object tracking, 3D positioning, supply chain management, inventory control, and access control. This paper concerns the fundamental problem of estimating RFID tag population size, which is needed in many applications such as tag identification, warehouse monitoring, and privacy sensitive RFID systems. In this paper, we propose a new scheme for estimating tag population size called Average Run based Tag estimation (ART). The technique is based on the average run-length of ones in the bit string received using the standardized framed slotted Aloha protocol. ART is significantly faster than prior schemes because its estimator has smaller variance compared to the variances of estimators of prior schemes. For example, given a required confidence interval of 0.1% and a required reliability of 99.9%, ART is consistently 7 times faster than the fastest existing schemes (UPE and EZB) for any tag population size. Furthermore, ART's estimation time is observably independent of the tag population sizes. ART is easy to deploy because it neither requires modification to tags nor to the communication protocol between tags and readers. ART only needs to be implemented on readers as a software module. ART works with multiple readers with overlapping regions.
【Keywords】: RFID; estimation; tags
【Paper Link】 【Pages】:377-388
【Authors】: John Whitbeck ; Marcelo Dias de Amorim ; Vania Conan ; Jean-Loup Guillaume
【Abstract】: While a natural fit for modeling and understanding mobile networks, time-varying graphs remain poorly understood. Indeed, many of the usual concepts of static graphs have no obvious counterpart in time-varying ones. In this paper, we introduce the notion of temporal reachability graphs. A (tau,delta)-reachability graph is a time-varying directed graph derived from an existing connectivity graph. An edge exists from one node to another in the reachability graph at time t if there exists a journey (i.e., a spatiotemporal path) in the connectivity graph from the first node to the second, leaving after t, with a positive edge traversal time tau, and arriving within a maximum delay delta. We make three contributions. First, we develop the theoretical framework around temporal reachability graphs. Second, we harness our theoretical findings to propose an algorithm for their efficient computation. Finally, we demonstrate the analytic power of the temporal reachability graph concept by applying it to synthetic and real-life datasets. On top of defining clear upper bounds on communication capabilities, reachability graphs highlight asymmetric communication opportunities and offloading potential.
【Keywords】: communication performance bounds; opportunistic networks; reachability; time-varying graphs
【Paper Link】 【Pages】:389-392
【Authors】: Michele Segata ; Falko Dressler ; Renato Lo Cigno ; Mario Gerla
【Abstract】: Automated platooning is one of the most challenging fields in the domain of ITS. Conceptually, platooning means creating clusters of vehicles which closely follow each other autonomously without action of the driver, neither for accelerating, nor for braking. This leads to several important benefits from substantially improved road throughput to increased safety. The control of such platoons depends on two components: First, radar is typically to be used to control the distance between the vehicles, and secondly, IVC helps managing the entire platoon allowing cars to join or to leave the group whenever necessary. Platooning systems have been mostly investigated in controlled environments such as dedicated highways with centralized management. However, platooning-enabled cars will be deployed gradually and might have to travel on highways together with other non-automated vehicles. We developed a combined traffic and network simulator for studying strategies and protocols needed for managing platoons in such mixed scenarios. We show the models needed and present first results using a simple IVC-based platoon management as a proof of concept.
【Keywords】: cooperative adaptive cruise control; platooning; simulation; vehicular networks
【Paper Link】 【Pages】:393-396
【Authors】: Jonathan Vestin ; Peter Dely ; Andreas Kassler ; Nico Bayer ; Hans Joachim Einsiedler ; Christoph Peylo
【Abstract】:
【Keywords】: 802.11; openflow; wireless
【Paper Link】 【Pages】:397-398
【Authors】: Kirill Kononenko
【Abstract】: The security of software systems is threatened by a wide range of attack vectors, such as buffer overflows, insecure information flow, and side channels, which can leak private information, e.g., by monitoring a program's execution time. Even if programmers manage to avoid such vulnerabilities in a program's source code or bytecode, new vulnerabilities can arise as compilers generate machine code from those representations. We propose a virtual execution environment for x86 machine code that combines information from compositional, static, and dynamic program analysis to identify vulnerabilities and timing channels, and uses code transformations to prevent those from being exploited. To achieve an appropriate level of performance as well as combine analysis results, our approach stores summary information in the form of conditional rules that can be shared among analyses.
【Keywords】: cloud computing; cryptography; cyber security; timing channels
【Paper Link】 【Pages】:399-402
【Authors】: Daniel Irwin ; Hrishikesh Venkataraman ; Gabriel-Miro Muntean
【Abstract】: Over the past three decades, several man-made vehicles have being sent into space to explore the extra-terrestrial bodies. As the search for water and other useful substances in the extra-terrestrial surfaces increases, this exploration activity is set to dramatically increase over the next decade (2020); with NASA planning to explore the surface of Mars, Moon and other planets and satellites. In this regard, it is imperative to build an extremely energy-efficient communication system that will cover a large area in the range of hundreds of kilometers which unfortunately is absolutely not possible today. A two-hop communication mechanism that has been well researched in the literature is insufficient to cover the extremely large distance of extra-terrestrial surface. In this paper, a novel three-hop cluster-based hierarchical communication architecture is proposed which could be easily extended to higher number of hops. In particular, it allows the individual rovers to move large distances for collecting data and at the same time provide an extremely energy-efficient mechanism for continuously exploring the surfaces. The simulation results show that in a Martian surface, the proposed three-hop design results in a higher capacity as compared to a single-hop or a cluster-based two-hop design even when the rovers move 100 km.
【Keywords】: extra-terrestrial surface; mars; multi-hop; rovers
【Paper Link】 【Pages】:403-406
【Authors】: Bastian Bloessl ; Stefan Joerer ; Fabian Mauroner ; Falko Dressler
【Abstract】: Inter-protocol interference is one of the most critical issues in wireless communication. For example, this becomes extremely problematic in environments where robustness and real-time communication need to be considered, e.g., in industrial automation or health care applications. Recently, possible approaches for interference mitigation have been described in the literature assuming that the interferer is known in advance. We contribute to this line of research with a framework for interferer detection and classification. Essentially, we use a simple IEEE 802.15.4 transceiver as for example used on the TelosB sensor motes to scan the 2.4 GHz ISM band. This band is used by different technologies including Bluetooth, WiFi, and cordless phones. The key challenge is the accurate timing of the scanning of the frequency band. The presented framework supports flexible descriptions of such scan jobs allowing to adapt to the detectors requirements, depending on the interfering protocols.
【Keywords】: ISM band; interference; interferer classification; interferer detection
【Paper Link】 【Pages】:407-410
【Authors】: Güliz Seray Tuncay ; Giacomo Benincasa ; Ahmed Helmy
【Abstract】: People-centric sensing is a novel apporach that exploits the sensing capabilities offered by smartphones and the mobility of users to sense large scale areas without requiring the deployment of sensors in-situ. Given the ubiquitous nature of smartphones, people-centric sensing is a viable and efficient solution for crowdsourcing data. In this work, we propose a fully distributed, opportunistic sensing framework that involves two main components which both work in an ad hoc fashion: Recruitment and Data Collection. We analyzed the feasibility of our distributed approach for both components through preliminary simulations. The results show that our recruitment method is able to select 66% of the nodes that are appropriate for the sensing activity and 88% of the messages sent by these selected nodes reach the sink by using our data collection method.
【Keywords】: DTN; crowdsourcing; mobile computing; opportunistic sensing; people-centric sensing
【Paper Link】 【Pages】:411-414
【Authors】: Egemen K. Çetinkaya ; Justin P. Rohrer ; Abdul Jabbar ; Mohammed J. F. Alenazi ; Dongsheng Zhang ; Dan Broyles ; Kamakshi Sirisha Pathapati ; Hemanth Narra ; Kevin Peters ; Santosh Ajith Gogi ; James P. G. Sterbenz
【Abstract】: End-to-end communication in highly-dynamic airborne networks is challenging due to the presence of highly mobile nodes and the inherent nature of wireless communication channels. Domain-specific protocols are required that can address these challenges and enable reliable transmission of data in this environment. We develop the ANTP (airborne network and transport protocols) suite that operates in this highly-dynamic environment while utilising cross-layer optimisations between the physical, MAC, network, and transport layers. We show how each component in the ANTP suite outperforms the traditional TCP/IP and MANET protocols through simulation using ns-3. Having verified these protocols through simulation and analysis, the next step towards deployment of the ANTP suite is developing a cross-platform implementation of the protocols. Towards this end we present an architecture for the protocol stack to be implemented in the Python programming language.
【Keywords】: DTN (disruption-tolerant network); MANET; airborne mobile wireless network; ns-3 simulation; python implementation
【Paper Link】 【Pages】:415-418
【Authors】: Riccardo Crepaldi ; Ryan Beavers ; Braden Ehrat ; Jason Sze ; Matt Jaeger ; Steven Biersteker ; Robin Kravets
【Abstract】:
【Keywords】: ad-hoc; internet access; opportunistic; vanet
【Paper Link】 【Pages】:419-422
【Authors】: Yuning Song ; Liang Liu ; Huadong Ma ; Athanasios V. Vasilakos
【Abstract】: Nature is an invaluable source of inspiration for long-standing computational problems. Genetic algorithms and ant colony optimization are the well-known successes. Drawing the inspirations from these successful experience, we exploit the computing model in a single-celled organism -- physarum polycephalum, and further design a new heuristic algorithm, Physarum Optimization, to the minimal exposure problem of wireless sensor networks. More importantly, our proposed physarum optimization algorithm can be also applied to the general Steiner tree problem.
【Keywords】: Steiner problem; bio-inspired computing; minimal exposure problem; physarum optimization
【Paper Link】 【Pages】:423-426
【Authors】: Dongsheng Zhang ; Santosh Ajith Gogi ; Dan Broyles ; Egemen K. Çetinkaya ; James P. G. Sterbenz
【Abstract】: A thorough understanding of the network behaviour when exposed to challenges is of paramount importance to construct a resilient MANET (mobile ad hoc network). However, modelling mobile and wireless networks as well as challenges against them is non-trivial due to dynamic and intermittent connectivity caused by channel fading and mobility of the nodes. We treat MANETs as time-varying graphs (TVGs) represented as a weighted adjacency matrix, in which the weights denote the link availability. We present how centrality-based attacks could affect network performance for different routing protocols. Furthermore, we model propagation loss models that represent realistic area-based challenges in wireless networks.
【Keywords】: MANET routing; mobile wireless network challenges; ns-3 simulation; resilience; survivability; time varying graphs
【Paper Link】 【Pages】:427-430
【Authors】: Marcel Großmann
【Abstract】: Mobile video consumption establishes as a massively growing market. To guarantee an acceptable quality of experience to the end user, current studies try to improve data transmissions on air interfaces. However, the bottleneck in cellular mobile networks is the traversal of the infrastructure. A paradigm to circumvent this fact and to increase the system's capacity is given by device-to-device communication in combination with proximity detection. Those networks promise scalability and performance improvements in utilizing scarce resources. This principle is easy to integrate into an existing mobile peer-to-peer video streaming system. In this study, we present measurements on application level to determine the performance that a smart device contributes to different wireless networks. The results outline that content uploading from smart devices is negligible in cellular networks, but shows acceptable performance in WiFi networks. This evaluation is the foundation to build a proximity enhanced video streaming system for mobile devices.
【Keywords】: cellular network; device-to-device communication; mobile video streaming; peer-to-peer network
【Paper Link】 【Pages】:431-434
【Authors】: Saumay Pushp ; Tae Hun Cho ; Jongwon Han ; Dongman Lee ; Junehwa Song ; Sunghee Choi
【Abstract】: In this paper, we propose a new class of message routing scheme for a distributed network which can scale up to the needs of a very large number of mobile users. We leverage the work in the GeoKad paper which uses the Distributed Geographic Table, allowing node retrieval from resources that are close to any given region. The paper addresses the problem regarding efficient message passing and peer misses. We propose a new routing scheme that addresses this kind of limitation. In fact, the problem can be solved in two ways, either by preserving the state of peer and further use a prediction algorithm or by better message routing. The proposed scheme is based on swarm intelligence (SI) and its attribute of exploit and explore. We leverage the statistical properties of time-varying network connectivity for opportunistic message forwarding. Considering the present 3G or Wi-Fi environment this approach can also help in optimizing energy as it can prevent query over flooding which is mostly encountered in such network scenarios.
【Keywords】: P2P; mobile computing; swarm intelligence
【Paper Link】 【Pages】:435-438
【Authors】: Norihisa Segawa ; Jun Sawamoto ; Masato Yazawa ; Haruo Tamaki
【Abstract】: We conducted long distance radio propagation experiments at 1-10mW/145MHz, to realize a low-power long-distance communication for wildlife research and disaster prevention telemetry. In this paper, we describe that we succeeded in long distance communications, from a ferryboat to the top of Mt. Asugiyama (elevation: 501m, distance: 15km) in Kure, Hiroshima, Japan, in the verification test of our method using 3W radio power. We found out that our method has sufficient capability to achieve such a long distance communication at 10BPS/10mW in battery cell operation on a marine, if we use SSB mode and the SNR in SSB bandwidth is better than -10dB.
【Keywords】: MAD-SS; direct sequence of spread spectrum communication (DS-SS); sensor network
【Paper Link】 【Pages】:439-442
【Authors】: Onur Altintas ; Yutaka Ihara ; Haris Kremo ; Hideaki Tanaka ; Masaaki Ohtake ; Takeo Fujii ; Chikara Yoshimura ; Keisuke Ando ; Kazuya Tsukamoto ; Masato Tsuru ; Yuji Oie
【Abstract】: Vehicular networking has significant potential to enable diverse range of applications, including safety and convenience. As the number of vehicles and applications using the specially designated wireless spectrum grow, one can expect substantial increase in the bandwidth requirements. In this paper and demonstration, we advocate that dynamic spectrum access techniques facilitating the utilization of white spaces for vehicles will be the first step towards solving the expected spectrum shortage. In the demonstration, we will introduce field tests of a multi-hop inter-vehicle communication system with distributed and autonomous TV white space channel selection, performed in Japan from January to February 2012. Furthermore, in addition to the field test videos, we will show an indoor emulation of the entire system used during the field tests in the vehicles.
【Keywords】: TV white space; dynamic spectrum access; multi-hop; spectrum sensing; vehicular communications
【Paper Link】 【Pages】:443-446
【Authors】: Johannes Morgenroth ; Sebastian Schildt ; Lars C. Wolf
【Abstract】: In this demo we present IBR-DTN for Android: IBR-DTN is a fully featured RFC5050 compliant Bundle Protocol implementation that can run on un-rooted Android devices starting from Android Version 2.3 (Gingerbread). IBR-DTN for Android supports all features of the IBR-DTN version for PCs and embedded systems. It is available in the Google Play Store for free. In addition to the protocol stack we provide two simple real world applications: a text messaging system and a push-to-talk application. They can serve as an example how to build DTN applications for mobile phones as both applications as well as the protocol implementation itself are open sourced.
【Keywords】: android; bundle protocol; dtn; mobile phones; smartphones
【Paper Link】 【Pages】:447-450
【Authors】: Gianpiero Costantino ; Fabio Martinelli ; Paolo Santi ; Dario Amoruso
【Abstract】: For this demo, we present an implementation of the FairPlay framework for secure two-party function computation on Android smartphones, which we call MobileFairPlay. MobileFairPlay allows high-level programming of several secure two-party protocols, including protocols for the Millionaire problem, set intersection, etc. All these functions are useful in the context of mobile social networks and opportunistic networks, where parties are often requested to exchange sensitive information (list of contacts, interest profiles, etc.) to optimise network operation.
【Keywords】: android; bluetooth; opportunistic networks; secure two-party computation
【Paper Link】 【Pages】:451-454
【Authors】: Hanno Wirtz ; David Martin ; Benjamin Grap ; Klaus Wehrle
【Abstract】: Typical scenarios in the city or on campus, show a high proliferation of wireless communication devices such as smartphones, laptops or netbooks. Wireless 802.11 networks between these devices allow for a spontaneous exchange of content or provision of services without the need for infrastructure-based services. However, the above mentioned proliferation of devices and therefore large number of networks hinders users in identifying and selecting the network that serves a specific request. We propose an approach to client-driven content-centric wireless networking in which the user specifically signals his request for a user, content item or service via 802.11 management frames. Upon reception of these frames, wireless devices that serve this request establish a dedicated wireless network on-demand. Our approach seamlessly integrates into the 802.11 association process and therefore provides support for unmodified wireless devices. Furthermore, by leveraging the wireless broadcast medium, we achieve pervasive service and peer discovery without the overhead of iterating through existing networks or running a traditional service discovery protocol.
【Keywords】: content-centric; opportunistic networking; pervasive communication; wireless communication
【Paper Link】 【Pages】:455-458
【Authors】: Noriyuki Suzuki ; Jane Louie Fresco Zamora ; Shigeru Kashihara ; Suguru Yamaguchi
【Abstract】: This demonstration presents SOSCast, an application that will assist the search for immobilized persons in a disaster area. When a catastrophic disaster such as an earthquake or tsunami occurs, people may be immobilized because of an injury or become trapped in buildings and debris. However, in such a situation, since conventional communication services are likely to be severely damaged, it would be difficult for immobilized persons to ask for rescue using their mobile phones. As a solution, we present SOSCast, which propagates SOS messages through direct communication between smartphones most especially inside the disaster area. By collecting these SOS messages, rescuers can estimate the locations of people who need help using the application. In this demonstration, we will show our prototype implementation of the SOSCast for SOS message processing and its map function to estimate the location of immobilized persons.
【Keywords】: bluetooth; disaster network; location estimation; smartphone; store-carry-forward
【Paper Link】 【Pages】:459-462
【Authors】: Dong Li ; Tarun Bansal ; Zhixue Lu ; Prasun Sinha
【Abstract】: Access to relative location of nearby vehicles on the local roads or on the freeways is useful for providing critical alerts to the drivers, thereby enhancing their driving experience as well as reducing the chances of accidents. The problem of determining the relative location of two vehicles can be broken into two smaller subproblems: (i) Relative lane localization, where a vehicle determines if the other vehicle is in left lane, same lane or right lane with respect to it, and (ii) Relative front-rear localization where it needs to be determined which of the two vehicles is ahead of the other on the road. In this demo, we show a novel antenna diversity based solution, MARVEL, that solves the problem of relative lane localization.
【Keywords】: location classification; smartphone; wireless ranging
【Paper Link】 【Pages】:463-466
【Authors】: Zhenjiang Li ; Cheng Li ; Wenwei Chen ; Jingyao Dai ; Mo Li ; Xiang-Yang Li ; Yunhao Liu
【Abstract】: In this demo, we propose a novel clock calibration approach called FLIGHT, which leverages the fact that the fluorescent light intensity changes with a stable period that equals half of the alternating current's. By tuning to the light emitted from indoor fluorescent lamps, FLIGHT can intelligently extract the light period information and achieve network wide time calibration by referring to such a common time reference. We address a series of practical challenges and implement FLIGHT in TelosB motes. In this demonstration, we will show that by taking advantage of the stability of the AC frequency, the detected light intensity, even from different lamps, exhibits a consistent and stable period. FLIGHT can achieve tightly synchronized time with low energy consumption. In addition, since FLIGHT is independent to the network message exchange, time synchronization can be retained even when the network is temporarily disconnected. Such characteristics particularly suit various mobility-enabled scenarios.
【Keywords】: clock calibration; energy efficiency; fluorescent lighting
【Paper Link】 【Pages】:467-470
【Authors】: Qiang Liu ; Ze Zhao ; Li Cui
【Abstract】: Dynamic spectrum access (DSA) networks can significantly improve the networks performance and efficiency of spectrum utilization. To harness this capability, spectrum sensing is a fundamental problem for DSA networks. This demonstration shows our wideband compressed spectrum sensing (WCSS) platform. This platform supports the controllable spectrum environment, high performance and low cost wideband spectrum sensing based USRP2, powerful and flexible compressed sensing computing platform based MATLAB. With this platform, we can research the wideband compressed spectrum sensing algorithm by actual and controllable spectrum environment.
【Keywords】: compressed sensing; dynamic spectrum access; platform; wideband spectrum sensing