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This research paper provides a brief description of the wireless sensor network and the protocol to be used. Through this technology, benefits are obtained that provide the sensor networks together with greater freedom when placing the sensors in the vicinity of the target. In wireless sensor networks, routing is a critical and important aspect. The work focuses on the performance of the quality of services in the wireless sensor network (WSN) under the AODV routing protocol. This document tries to characterize the AODV protocol by performing simulations in the NS3 (Network Simulator Version 3) program. In the simulations of the AODV protocol, a set of metrics that can be used for comparisons in different scenarios are shown. The main objective of this document will be to offer a suitable simulation environment to determine the operation of the protocol to be used in wireless sensor networks. [ABSTRACT FROM AUTHOR]

Analyzing the Stable election protocol (SEP) in wireless sensor networks and aiming at the problem of inhomogeneous cluster-heads distribution and unreasonable cluster-heads selectivity and single hop transmission in the SEP, a SEP Protocol based on community structure of node degree (SEP-CSND) is proposed. In this algorithm, network node deployed by using grid deployment model, and the connection between nodes established by setting up the communication threshold. The community structure constructed by node degree, then cluster head is elected in the community structure. On the basis of SEP, the node's residual energy and node degree is added in cluster-heads election. The information is transmitted with mode of multiple hops between network nodes. The simulation experiments showed that compared to the classical LEACH and SEP, this algorithm balances the energy consumption of the entire network and significantly prolongs network lifetime. [ABSTRACT FROM AUTHOR]

Despite years of innovative research and development, gigabit-speed 60 GHz wireless networks are still not mainstream. The main concern for network operators and vendors is the unfavorable propagation characteristics due to short wavelength and high directionality, which renders the 60 GHz links highly vulnerable to blockage and mobility. However, the advent of multi-band chipsets opens the possibility of leveraging the more robust WiFi technology to assist 60 GHz in order to provide seamless, Gbps connectivity. In this paper, we design and implement MUST, an IEEE 802.11-compliant system that provides seamless, high-speed connectivity over multi-band 60 GHz and WiFi devices. MUST has two key design components: (1) a WiFi-assisted 60 GHz link adaptation algorithm, which can instantaneously predict the best beam and PHY rate setting, with zero probing overhead; and (2) a proactive blockage detection and switching algorithm which can re-direct ongoing user traffic to the robust interface within sub-10 ms latency. Our experiments with off-the-shelf 802.11 hardware show that MUST can achieve 25-60% throughput gain over state-of-the-art solutions, while bringing almost 2 orders of magnitude cross-band switching latency improvement. [ABSTRACT FROM AUTHOR]

Wireless nodes are small devices which are distributed in the region of interest. These small devices measure selected environmental variables, communicate with each other and send data to a local storage. Wireless nodes can be distributed either in internal or external environment. Communication distance is one of factors that has to be known at the beginning of the distribution process. Communication distance depends on a lot of factors such as used protocol, technical parameters of the node, obstacles situated in the communication path and weather conditions. The communication distance between Jennic nodes with different antenna modules and a coordinator was tested in the small area. The nodes communicated on the basis of JeNet protocol. Four different scenarios represent the results of investigation of the communication distance at which the Jennic nodes are able reliable communicate. Knowledge of reliable communication distance is one of parameters used in the distribution process. [ABSTRACT FROM AUTHOR]

In this work, we explore a new networking mechanism with smart glasses, through which users can express their interest and connect to a target simply by a gaze. Doing this, we attempt to let wearable devices understand human attention and intention, and pair devices carried by users according to such attention and intention. To achieve this ambitious goal, we propose a proof-of-concept system iGaze, a visual attention driven networking suite: an iGaze glass (hardware), and a networking protocol VAN (software). Our glass, iGaze glass, is a low-cost head-mounted glass with a camera, orientation sensors, microphone and speakers, which are embedded with our software for visual attention capture and networking. A visual attention driven networking protocol (VAN) is carefully designed and implemented. In VAN, we design an energy efficient and highly accurate visual attention determination scheme using single camera to capture user's communication interest and a double-matching scheme based on visual direction detection and Doppler effect of acoustic signal to lock the target devices. Using our system, we conduct a series of trials for various application scenarios to demonstrate the effectiveness of our system. [ABSTRACT FROM AUTHOR]

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 broad- cast protocols and that the total number of packet transmissions can be reduced consistently by 47% on average. [ABSTRACT FROM AUTHOR]

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 wholehome 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-ofconcept 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%. [ABSTRACT FROM AUTHOR]

Opportunistic networks are systems with highly distributed operation, relying on the altruistic cooperation of heterogeneous, and not always software- and hardware-compatible user nodes. Moreover, the absence of central control makes them vulnerable to malicious attacks. In this paper, we take a fresh look at the resilience of opportunistic forwarding to these challenges. In particular, we introduce and promote the use of metric envelopes as a resilience assessment tool. Metric envelopes depart from the standard practice of average value analysis and explicitly account for the differentiated impact that a challenge may have on the forwarding performance due to node heterogeneity (device capabilities, mobility) and attackers' intelligence. The use of metric envelopes is demonstrated in the case of three challenges: jamming, hardware/software failures and incompatibilities, and free-riding phenomena. For each challenge, we first devise heuristics to generate worst- and best-case realization scenarios that can approximate the metric envelopes. Then we derive the envelopes of common performance metrics for three popular forwarding protocols under a comprehensive range of mobility patterns. The metric envelope approach enables more informed choices in opportunistic forwarding whenever network resilience considerations become important. [ABSTRACT FROM AUTHOR]

The deployment of automatic solutions to support networks' self-configuration is increasingly capturing the attention of the Internet community. In existing networks, information mainly retrieved off-line is used to configure different network elements and this configuration remains fairly static during the period of time when the network is in operation. Future networking technologies expects a new level of dynamicity and heterogeneity in which networks' architectures and protocols must enable the cooperation of heterogeneous devices. This cooperation should be transparent, established on demand, and thus support "plug-and-play" operation. In this context, situations where new networks would be spontaneously created will happen and, consequently, networks might dynamically adapt themselves to environments characteristics during their entire lifecycle. In this paper we present an evaluation of the influence that a self-configuration mechanism might have in network operation considering some perspectives, such as its overhead and the influence it would have over running applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 spectrumagile 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 10μs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 counterintuitive approach of encouraging interference can be exploited to increase network capacity significantly and simplify network design. We design and implement AutoMAC, 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 AutoMAC 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 [ABSTRACT FROM AUTHOR]

A delay tolerant network (DTN) deals with the issue of frequently interrupted connections and relaxes the need for a continuous end-to-end relation between nodes. The Bundle Protocol is the typical way to set-up a DTN, but requires a common time in the whole network. Further, globally synchronized timestamps are required by many mechanisms like cryptography protocols or global event ordering. Since standard time synchronization approaches from classical networking do not work in DTNs, we introduce a novel algorithm to distribute a time reference in such networks. Our approach rates the quality of the local time with respect to the accuracy of the local clock. We show that this simple and self-aligning algorithm can provide an adequate accuracy depending on the inter-contact times between the nodes [ABSTRACT FROM AUTHOR]

In this work, we investigate on the use of Sugeno fuzzy inference system (FIS) in route selection for mobile Ad-Hoc networks (MANETs). Sugeno FIS is introduced into Ad-Hoc On Demand Multipath Distance Vector (AOMDV) routing protocol, which is derived from its predecessor, Ad-Hoc On Demand Distance Vector (AODV). Instead of using the conventional way that considering only a single metric to choose the best route, our proposed fuzzy decision making model considers up to three metrics. In the model, the crisp inputs of the three parameters are fed into an FIS and being processed in stages, i.e., fuzzification, inference, and defuzzification. Finally, after experiencing all the stages, a single value score is generated from the combination metrics, which will be used to measure all the discovered routes credibility. Results obtained from simulations show a promising improvement as compared to AOMDV and AODV. [ABSTRACT FROM AUTHOR]

One of the most important challenges in mobile Internet Protocol (IP) is to provide service for a mobile node to maintain its connectivity to network when it moves from one domain to another. IP is responsible for routing packets across network. The first major version of IP is the Internet Protocol version 4 (IPv4). It is one of the dominant protocols relevant to wireless network. Later a newer version of IP called the IPv6 was proposed. Mobile IPv6 is mainly introduced for the purpose of mobility. Mobility management enables network to locate roaming nodes in order to deliver packets and maintain connections with them when moving into new domains. Handoff occurs when a mobile node moves from one network to another. It is a key factor of mobility because a mobile node can trigger several handoffs during a session. This paper briefly explains on mobile IP and its handoff issues, along with the drawbacks of mobile IP. [ABSTRACT FROM AUTHOR]

The rapidly increasing popularity of IEEE 802.11 WLANs has created unprecedented levels of congestion in the unlicensed frequency bands, especially in densely populatedurban areas. Performance experienced by end-users in such deployments is significantly degraded due to contention and interference among adjacent cells. In this paper, we develop novel metrics and insights that we use for dynamic frequency selection, incorporating the various features that affect interference. The proposed scheme features a novel client feedback mechanism, which enables nodes of the cell, as well as nodes belonging to different cells, to contribute to interference measurements. Furthermore, we incorporate a traffic monitoring scheme that makes the system aware of prevailing traffic conditions. We design a distributed protocol, through which messages containing the information above are passed by the stations to the access-points, where the frequency selection is performed in a dynamic form. The proposed algorithm is implemented in the Mad-WiFi open source driver and is validated through extensive testbed experimentsin both an indoor RF-Isolated environment, as well as in a interference-rich, large-scale wireless testbed. Results obtained under a wide range of settings, indicate that our algorithm improves total network throughput, up to a factor of 7.5, compared to state-of-the-art static approaches. [ABSTRACT FROM AUTHOR]

Multihop wireless networks, such as sensor-, ad hoc- and mesh-networks, although different share some common characteristics. All these networks exhibit link dynamics. Protocols designed for these wireless networks must overcome the challenge of link dynamics and the resulting churn in network topology. Due to structural and topological similarities, protocols developed for one class of wireless network should also be applicable in the other classes. However, network-layer protocols are usually developed for and tested in only one class of wireless network due to the lack of a platform that allows testing of protocols across different classes of networks. As a result, we unnecessarily constrain the range of settings and scenarios in which we test network protocols. In this paper, we present TinyWifi, a platform for executing native sensornet protocols on Linux-driven wireless devices. TinyWifi builds on nesC code base that abstracts from TinyOS and enables the execution of nesC-based protocols in Linux. Using this abstraction, we expand the applicability and means of protocol execution from one class of wireless network to another without re-implementation. We demonstrate the generality of TinyWifi by evaluating four well-established protocols on IEEE 802.11 and 802.15.4 based testbeds using a single implementation. [ABSTRACT FROM AUTHOR]

Wireless network testbeds have emerged as a valuable alternative to network simulation, but actually using them for experiments presents a number of challenges. We use the ORBIT testbed at Rutgers University, New Jersey, USA as a case study to illustrate the most important issues in this context. We performed several types of evaluation tests on ORBIT, as well as a series of equivalent experiments with up to 50 nodes, which were done also on the QOMB wireless network emulation testbed, and by using the QualNet network simulator. We conclude that a testbed such as ORBIT provides a viable approach to network testing, although this is conditioned by an awareness of the potential pitfalls that may affect experimental results; a series of lessons we learned from our experience is included in the paper. We also show that real-world trials on ORBIT can be broadly reproduced through emulation and even through simulation. [ABSTRACT FROM AUTHOR]

After the emergence of IEEE 802.11, Wi-Fi has made a big impact on the wireless network environment. With decent data rate available lately at low cost, implementation of wireless networks are growing all over the place. To deliver bandwidth of around 54 Mbps, 802.11g was released. This paper seeks to compare wireless N (802.11n) and wireless G (802.11g) standards in terms of performance and reliability. Since security cannot be overemphasized when dealing with Wireless LAN, this paper also looks at the security implementation of these standards. It is worth nothing that the effectiveness of a wireless network depends on the structure of the building, interference with other networks and security implemented. This paper could be useful for those who want increase in bandwidth with strong security encryption activated. It is tuned to small and medium scale enterprises and also home users. [ABSTRACT FROM AUTHOR]

ZigBee is an emerging standard for Wireless Sensor Networks (WSNs). It targets low distance, low data rate, low power consumption and low cost applications. According to standard nomenclature, it implements a Low Rate-Wireless Personal Area Network (LR-WPAN). ZigBee defines upper layers (network and application) of the ISO protocol reference model. On the contrary, in regards to the physical and data link ones, it relies over another standard, the well accepted IEEE802.15.4, which offers a gross transfer rate of 250 kbps in the 2.4 GHz ISM unlicensed band. Although ZigBee is designed for event-based applications, ZigBee is designed as a low-cost, low-power, low-data rate wireless mesh technology. There are many wireless sensor networks in which it is required to send information to the pan coordinator continuously and simultaneously. Our purpose here in this paper is to test zigbee for such kind of networks where multiple events take place simultaneously. Also we want to see the effect of increasing the number of events in a scenario, so that we can find out its effect. [ABSTRACT FROM AUTHOR]

Cooperative communications, in which a relay node assists the source node to deliver its packets to the destination node thus adding diversity, is gaining more attention within the research community. The initial studies on the physical layer have shown significant gains from cooperative diversity in terms of reliability, coverage range and energy efficiency. A Cooperative Automatic Repeat reQuest MAC protocol, (C-ARQ), has been proposed to utilize cooperative diversity from the MAC layer. In this paper, we inspect this novel C-ARQ protocol to check its integrity and validity using formal methods. The protocol logic is modeled in SDL and implemented in PROMELA. The functionality of the C-ARQ protocol is confirmed through simulations and verified using the SPIN tool. [ABSTRACT FROM AUTHOR]

Radio Frequency Identification (RFID) is currently the hottest technology in wireless applications area. Its unique advantages such as data transmission with extreme low power or even without power in tag can be the biggest beneficial for goods management. Software Defined Radio (SDR) is a wireless communications system where all of the signal processing is implemented in software. By simply downloading a new program, a software radio is able to interoperate with different wireless protocols, incorporate new services, and upgrade to new standards. In this paper, we build an RFID application simulation environment over the SDR. We do the source to sink transmission simulation by using Quadrature Amplitude Modulation, Then, we compare the differences of BER versus SNR performances for input and output signals. [ABSTRACT FROM AUTHOR]

This paper explores metrics that capture to what degree packet reception on different links is correlated. Specifically, it explores metrics that shed light on when and why opportunistic routing and network coding protocols perform well (or badly). It presents a new metric, ? that, unlike existing widely used metrics, has no bias based on the packet reception ratios of links. This lack of bias makes ? a better predictor of performance of opportunistic routing and network coding protocols. Comparing Deluge and Rateless Deluge, Deluge's network coding counterpart, we find that ? can predict which of the two is best suited for a given environment. For example, irrespective of the packet reception ratios of the links, if the average ? of the link pairs is very high (close to 1.0), then using a protocol that does not code works better than using a network coding protocol. Measuring ? on several 802.15.4 and 802.11 testbeds, we find that it varies significantly across network topologies and link layers. ? can be a metric for quantifying what kind of a network is present and help decide which protocols to use for that network. [ABSTRACT FROM AUTHOR]

In this paper, we present Esense: a new paradigm of communication between devices that have fundamentally different physical layers. The same communication framework also works between devices that have the same physical layer, which are out of communication range but within carriersense range. Esense is based on sensing and interpreting energy profiles. While our ideas are generic enough to be applicable in a variety of contexts, we illustrate the usefulness of our ideas by presenting novel solutions to existing problems in three distinct research domains. As part of these solutions, we demonstrate the ability to communicate between devices that follow two different standards: IEEE 802.11 and 802.15.4. We build an "alphabet set": a set of signature packet sizes which can be used for Esense. For this, we take a measurement based approach by considering WiFi traces from actual deployments. We then analyze the channel activity resulting from these traces and build an appropriate alphabet set for Esense communication. Our results show that we could potentially construct an alphabet of size as high as 100; such a large alphabet size promises efficient Esense communication. We also validate this alphabet set via a prototype implementation, and show that effective communication is indeed feasible even when both sides use different physical layers. [ABSTRACT FROM AUTHOR]

The technology of Dynamic Spectrum Access (DSA) can utilize unused licensed bands not being used by licensed users to improve the capacity and throughput of multi-hop wireless networks working on the ISM bands. However, DSA also brings us a new challenge: how to network the radios in multi-hop DSA networks to improve network performance, such as throughput and end-to-end delay? To address this issue, we propose a STability-Aware Routing Protocol (STARP) for multi-hop DSA networks. STARP can find the most stable path among multi paths to the destination for upper layer protocol. STARP evaluates path stability by utilizing a novel routing metric, which takes into account spectrum switching frequency, spectrum usage, and path length together. Simulation results of NS-2 show STARP is efficient and robust. In addition, STARP can achieve good improvement of TCP performance and shorten end-to-end packet delay significantly. [ABSTRACT FROM AUTHOR]

We present the RapidMesh toolkit for rapid protocol simulation, implementation and experimentation of wireless mesh networks. RapidMesh utilizes declarative networking, a declarative, database-inspired extensible infrastructure that uses query languages to specify behavior. RapidMesh integrates a declarative networking engine with the emerging ns-3 network simulator. The same declarative specifications can also be used as actual implementations using the ns-3 network emulator, hence providing a bridge between simulation and testbed-based experimentation. We demonstrate that RapidMesh enables a variety of wireless routing protocols and neighbor discovery protocols can be synthesized via compact declarative specications. We experimentally validate declarative MANET routing protocols in dynamic settings within RapidMesh operating in ns-3 simulation environment and on the ORBIT wireless testbed. [ABSTRACT FROM AUTHOR]

In this paper we present Topology and Link Quality Assessment Protocol (TLQAP), which we have implemented as a wireless testbed management framework component, that is used to inspect link quality between wireless testbed nodes and appropriately map them to user experiment requirements. TLQAP is mainly an OSI layer 2 design for fixed location, non RF-isolated wireless testbed deployments, which assesses interconnection topology and link quality by estimating packet delivery ratio (PDR) and transmission delay at each node for all requested channel, rate and transmission power combinations. Moreover, TLQAP builds a measurement history log and creates a channel utilization profile, in the context of each testbed node, for all the nearby testbedexternal devices that operate independently in the region and are not under the management framework control. The analysis of this information enables TLQAP to choose the channels that have the highest probability of being free during an experiment. TLQAP OSI layer 2 component has been implemented in the click modular router framework and the controller component has been integrated with OMF management framework for wireless testbeds. To outline TLQAP benefits, we have performed experiments on our ORBIT node testbed and we compare it to an existing application level measuring tool. [ABSTRACT FROM AUTHOR]

We address the joint problem of traffic routing and mobility support in wireless mesh networks that are built by many fixed nodes and few mobile nodes. We focus on a vehicular setting, where buses or streetcars connect to different fixed mesh nodes as they move in a urban environment. First, through simulation we identify the best candidate for routing traffic in such a scenario and we find that our improved version of the BATMAN protocol, named smart window BATMAN, outperforms other reactive and proactive approaches. Then, we develop a testbed which includes both roadside mesh nodes and vehicular mesh nodes. There, we implement the selected routing solution, along with a handover scheme that allows vehicles to connect to the different mesh nodes in a seamless manner. Our testbed and performance assessment show that mobility can be efficiently supported in mesh networks, and that our modified version of the BATMAN protocol is a good candidate for sustaining the handover of UDP streams in a seamless manner. [ABSTRACT FROM AUTHOR]

The mobility model in next generation of wireless network(4G) has become a very hot topic. To address the issue, various protocols have been developed to meet the user's demand of mobile Internet application. These heterogeneous network environments need to adapt for users that require a specific quality of service, especially for real-time and multimedia applications. In this paper we describe a new model of network selection using symbolic linear regression. [ABSTRACT FROM AUTHOR]

An Ad-hoc network is a collection of mobile nodes, which are forming a network without requiring any pre-established infrastructure. A number of protocols have been developed insofar to facilitate the administration, management and operation of such networks; for packet routing, in particular, two of the most widespread protocols are DSR (Dynamic Source Routing) and SSR (Signal Stability Routing). In this work, we use simulation to assess and compare the performance of these two protocols. Although the approaches taken by these protocols share a considerable number of common features, our simulation has shown that differences in performance figures do exist, which may be attributed either to implementation issues or interlayer operations. In our study, we have considered different network loads, number of nodes within the network and mobility parameters. [ABSTRACT FROM AUTHOR]

Accurately selecting modulation rates for time-varying channel conditions is critical for avoiding performance degradations due to rate over-selection when channel conditions degrade or under-selection when channel conditions improve. In this paper, we design a custom cross-layer framework that enables (i) implementation of multiple and previously unimplemented rate adaptation mechanisms, (ii) experimental evaluation and comparison of rate adaptation protocols on controlled, repeatable channels as well as residential urban and downtown vehicular and non-mobile environments in which we accurately measure channel conditions with 100- μs granularity, and (iii) comparison of performance on a per-packet basis with the ideal modulation rate obtained via exhaustive experimental search. Our evaluation reveals that SNR-triggered protocols are susceptible to over-selection from the ideal rate when the coherence time is low (a scenario that we show occurs in practice even in a nonmobile topology), and that "in-situ" training can produce large gains to overcome this sensitivity. Another key finding is that a mechanism effective in differentiating between collision and fading losses for hidden terminals has severely imbalanced throughput sharing when competing links are even slightly heterogeneous. In general, we find trained SNR-based protocols outperform loss-based protocols in terms of the ability to track vehicular clients, accuracy within outdoor environments, and balanced sharing with heterogeneous links (even with physical layer capture). [ABSTRACT FROM AUTHOR]

This paper establishes a framework for the automated generation of networking protocols. The need for the rapid design of networking protocols in application-specific contexts has increased dramatically over the past five years. Each new application requires high performance in its own domain, as well as a rapid design cycle. Further, changes in physical layer technology quickly render previously high-performance protocols poor performance. Currently, there are no tools to automate the design of networking protocols. This paper addresses the challenge of building such tools. It proposes a methodology and a design chain for the automated generation of networking protocols, with the following novel ideas: (1) Formulation of the network protocol problem such that the exchange of protocol control information can be specified as part of the optimization program, (2) Optimal waveform generation, which specifies the optimal exchange of both control information and data, (3) Protocol Extraction: The extraction of the optimal protocol as a minimal description of the optimal waveforms. This methodology has the potential to dramatically change the future of networking protocol design by moving protocol design to a more abstract level, finding high-performance protocols not easily discovered by human intuition, and reducing the currently long protocol design cycles. [ABSTRACT FROM AUTHOR]

This paper describes an algorithm to compute lists of people and devices that are physically nearby to a mobile user based on the analysis of signals from existing wireless networks. The system evaluates proximity by classifying the degree of similarity of the Wi-Fi scan data through a statistical Gaussian Mixture Model. It recognizes when the devices are in the same area, and, in this case, it distinguishes three proximity levels: High (e.g. same room), Medium (e.g. same floor) and Low (e.g. same building). The algorithm can be deployed on a remote server that receives Wi-Fi scanning data (including MAC addresses and signal strength) from mobile devices. The server estimates proximity by extracting a set of features from each received pair of Wi- Fi data, feeding them to the GMM model and selecting the category with greatest probability. The method presented in the paper does not require calibration and leverages on existing Wi-Fi signals, while obtaining a percentage of correct discrimination among three levels near to 90%. [ABSTRACT FROM AUTHOR]

Even though hot spots and mesh networks increasingly realize the long-standing vision of ubiquitous Internet access, our understanding of wireless protocols and system is still in its infancy. To analyze and debug the current and new protocols, packet-level accurate information of protocol status is crucially needed. Thus, this paper introduces PaPMo (Packet accurate Protocol Monitor), an active monitoring tool that captures snapshots of the protocol status as packets pass through the different layers and over distributed nodes. By merging and correlating the captured information, PaPMo is able to provide packet-level accurate information of deployed wireless network behavior that is currently available only via simulations. We show that PaPMo is able to correlate MAC-layer events, such as packet loss due to queue overflow, with TCP congestion control behavior at the accuracy of microseconds and with high fidelity. [ABSTRACT FROM AUTHOR]

An ability to accurately classify observed packet errors according to their root cause: physical layer or MAC layer contention, in 802.11 networks, opens up many opportunities for performance improvement at the both the MAC and IP layers. We investigate two orthogonal ways to achieve this, and present a methodology, the 'map', for clearly visualizing the results free of packet size and rate 'bias'. [ABSTRACT FROM AUTHOR]

Although there are numerous time synchronization algorithms recently proposed for terrestrial wireless sensor networks, none of these could be directly applied to underwater acoustic sensor networks. This is because they typically assume that the propagation delay is negligible, which is not the case in underwater. Furthermore, the sensor nodes in underwater tend to have some degree of mobility due to wind or ocean current, which complicates the problem even more by introducing time-varying delay. In this paper, we propose a cluster-based synchronization algorithm for underwater acoustic mobile networks, called "MU-Sync". Our design avoids frequent re-synchronization by estimating both the clock skew and offset. As underwater mobile networks experience both time-varying and long propagation delay, previous works that estimate the clock skew using a single least square error linear regression tend to be inaccurate. In the MU-Sync, the clock skew is estimated by performing the linear regression twice over a set of local time information gathered through message exchanges. The first linear regression enables the cluster head to offset the effect of long and varying propagation delay; the second regression in turn obtains the estimated skew and offset. With the help of MAC-level time stamping, we can further reduce the nondeterministic errors that are commonly encountered by those synchronization algorithms that rely on message exchanges. [ABSTRACT FROM AUTHOR]

As municipalities study opportunities to build large Wi-Fi networks to cover their territory, it is interesting to compare these initiatives' coverage, performance, and cost to other existing cellular high-speed solutions. This paper examines one particular case in the city of Longmont, CO. Coverage and throughput measurements are performed in a residential area; cost analyses and consumer perceptions are examined as well. [ABSTRACT FROM AUTHOR]

This paper presents a proximity-based authentication approach for the Internet of Things (IoT) that works in-band by solely utilizing the wireless communication interface. The novelty of this approach lies in its reliance on ambient radio signals to infer proximity within about one second, and in its ability to expose imposters located several meters away. We identify relevant features sensed from the RF channel to establish a notion of proximity across co-located low-power devices. We introduce our proximity-based authentication protocol and show the feasibility of our approach with an early prototype using off-the-shelf 802.15.4 sensors and an evaluation conducted in a real-world environment. [ABSTRACT FROM AUTHOR]