ieee projects 2012 2013 - mobile computing

Elysium Technologies Private Limited Approved by ISO 9001:2008 and AICTE for SKP Training Singapore | Madurai | Trichy | Coimbatore | Cochin | Kollam | Chennai http://www.elysiumtechnologies.com, [email protected]

IEEE Final Year Projects 2012 |Student Projects | Mobile Computing Projects

IEEE FINAL YEAR PROJECTS 2012 – 2013

MOBILE COMPUTING

Corporate Office: Madurai

227-230, Church road, Anna nagar, Madurai – 625 020.

0452 – 4390702, 4392702, +9199447933980

Email: [email protected], [email protected]

Website: www.elysiumtechnologies.com

Branch Office: Trichy

15, III Floor, SI Towers, Melapudur main road, Trichy – 620 001.

0431 – 4002234, +919790464324.

Email: [email protected], [email protected].


Branch Office: Coimbatore

577/4, DB Road, RS Puram, Opp to KFC, Coimbatore – 641 002.

+919677751577

Website: Elysiumtechnologies.com, Email: [email protected]

Branch Office: Kollam

Surya Complex, Vendor junction, Kollam – 691 010, Kerala.

0474 – 2723622, +919446505482.

Email: [email protected].


Branch Office: Cochin

4th

Floor, Anjali Complex, near south over bridge, Valanjambalam,

Cochin – 682 016, Kerala.

0484 – 6006002, +917736004002.

Email: [email protected], Website: www.elysiumtechnologies.com

mailto:[email protected]









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MOBILE COMPUTING 2012 - 2013

Characterizing the performance of ad hoc networks is one of the most intricate open challenges; conventional ideas

based on information-theoretic techniques and inequalities have not yet been able to successfully tackle this problem in

its generality. Motivated thus, we promote the totally asymmetric simple exclusion process (TASEP), a particle flow

model in statistical mechanics, as a useful analytical tool to study ad hoc networks with random access. Employing the

TASEP framework, we first investigate the average end-to-end delay and throughput performance of a linear multihop

flow of packets. Additionally, we analytically derive the distribution of delays incurred by packets at each node, as well

as the joint distributions of the delays across adjacent hops along the flow. We then consider more complex wireless

network models comprising intersecting flows, and propose the partial mean-field approximation (PMFA), a method that

helps tightly approximate the throughput performance of the system. We finally demonstrate via a simple example that

the PMFA procedure is quite general in that it may be used to accurately evaluate the performance of ad hoc networks

with arbitrary topologies.

We propose a broadcast algorithm suitable for a wide range of vehicular scenarios, which only employs local

information acquired via periodic beacon messages, containing acknowledgments of the circulated broadcast

messages. Each vehicle decides whether it belongs to a connected dominating set (CDS). Vehicles in the CDS use a

shorter waiting period before possible retransmission. At time-out expiration, a vehicle retransmits if it is aware of at

least one neighbor in need of the message. To address intermittent connectivity and appearance of new neighbors, the

evaluation timer can be restarted. Our algorithm resolves propagation at road intersections without any need to even

recognize intersections. It is inherently adaptable to different mobility regimes, without the need to classify network or

vehicle speeds. In a thorough simulation-based performance evaluation, our algorithm is shown to provide higher

reliability and message efficiency than existing approaches for nonsafety applications.

We propose a broadcast algorithm suitable for a wide range of vehicular scenarios, which only employs local

information acquired via periodic beacon messages, containing acknowledgments of the circulated broadcast

messages. Each vehicle decides whether it belongs to a connected dominating set (CDS). Vehicles in the CDS use a

shorter waiting period before possible retransmission. At time-out expiration, a vehicle retransmits if it is aware of at

least one neighbor in need of the message. To address intermittent connectivity and appearance of new neighbors, the

A Statistical Mechanics-Based Framework to Analyze Ad Hoc Networks with Random

Access

A Fade-Level Skew-Laplace Signal Strength Model for Device-Free Localization with

Wireless Networks

Acknowledgment-Based Broadcast Protocol for Reliable and Efficient Data Dissemination

in Vehicular Ad Hoc Networks



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evaluation timer can be restarted. Our algorithm resolves propagation at road intersections without any need to even

recognize intersections. It is inherently adaptable to different mobility regimes, without the need to classify network or

vehicle speeds. In a thorough simulation-based performance evaluation, our algorithm is shown to provide higher

reliability and message efficiency than existing approaches for nonsafety applications.

Displays based on organic light-emitting diode (OLED) technology are appearing on many mobile devices. Unlike liquid

crystal displays (LCD), OLED displays consume dramatically different power for showing different colors. In particular,

OLED displays are inefficient for showing bright colors. This has made them undesirable for mobile devices because

much of the web content is of bright colors. To tackle this problem, we present the motivational studies, design, and

realization of Chameleon, a color adaptive web browser that renders webpages with power-optimized color schemes

under user-supplied constraints. Driven by the findings from our motivational studies, Chameleon provides end users

with important options, offloads tasks that are not absolutely needed in real time, and accomplishes real-time tasks by

carefully enhancing the codebase of a browser engine. According to measurements with OLED smartphones,

Chameleon is able to reduce average system power consumption for web browsing by 41 percent and is able to reduce

display power consumption by 64 percent without introducing any noticeable delay.

In this paper, we propose a fuzzy Q-learning-based MIMO configuration mode and MCS level (FQL-MOMS) selection

scheme for high speed packet access evolution (HSPA+) systems. The FQL-MOMS selection scheme intends to enhance

the system throughput under the block error rate (BLER) requirement guarantee. It will determine an appropriate MIMO

configuration mode and MCS (modulation and coding scheme) level for packet data transmission in HSPA+ systems,

under the situations that the channel status is varying and the channel quality indication (CQI) has report delay. The

FQL-MOMS scheme considers not only the reported CQI and the last transmission result but also the BLER performance

metric and the transmission efficiency. Moreover, it is effectively configured, where the fuzzy rules and the

reinforcement signals for the Q-learning algorithm are sophisticatedly designed. Simulation results show that the

proposed FQL-MOMS scheme increases the system throughput by up to 49.3% and 35.9%, compared to the

conventional adaptive threshold selection (ATS) scheme [12] and the Q-HARQ scheme [14], respectively, under the

BLER requirement fulfillment.

During the last decade, Reactive Jamming Attack has emerged as a great security threat to wireless sensor networks,

due to its mass destruction to legitimate sensor communications and difficulty to be disclosed and defended.

An MIMO Configuration Mode and MCS Level Selection Scheme by Fuzzy Q-Learning for

HSPA+ Systems

Chameleon: A Color-Adaptive Web Browser for Mobile OLED Displays

A Trigger Identification Service for Defending Reactive Jammers in WSN



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Considering the specific characteristics of reactive jammer nodes, a new scheme to deactivate them by efficiently

identifying all trigger nodes, whose transmissions invoke the jammer nodes, has been proposed and developed. Such a

trigger-identification procedure can work as an application-layer service and benefit many existing reactive-jamming

defending schemes. In this paper, on the one hand, we leverage several optimization problems to provide a complete

trigger-identification service framework for unreliable wireless sensor networks. On the other hand, we provide an

improved algorithm with regard to two sophisticated jamming models, in order to enhance its robustness for various

network scenarios. Theoretical analysis and simulation results are included to validate the performance of this

framework.

Collaborative Business Processes (cBPs) form the backbone of enterprise integration. With the growing reliance on the

Network Mobility (NEMO) efficiently manages the mobility of multiple nodes that moves together as a mobile network. A

major limitation of the basic protocol in NEMO is the inefficient route between end hosts. A number of prefix delegation-

based schemes have been proposed in the literature to solve the route optimization problem in NEMO. Approaches used

by the schemes trade off delivery of packets through the partially-optimized route with signaling and other processing

overheads. Cost of delivering packets through the partially-optimized route along with signaling and other processing

cost need to be measured to find out the gain from tradeoff. However, cost analysis performed so far on NEMO

protocols consider only the cost of signaling. In this paper, we have developed analytical framework to measure the

costs of the basic protocol for NEMO, and four representative prefix delegation-based schemes. Our results show that

cost of packet delivery through the partially-optimized route dominates over other costs. Therefore, optimizing the route

completely is preferable to reduction of signaling as far as cost of network mobility is concerned. Our cost analysis

framework will help in decision making to select the best route optimization scheme depending on the load imposed by

the scheme on the infrastructure.

This paper proposes a novel medium access control (MAC) scheme for multichannel cognitive radio (CR) ad hoc

networks, which achieves high throughput of CR system while protecting primary users (PUs) effectively. In designing

the MAC scheme, we consider that the PU signal may cover only a part of the network and the nodes can have the

different sensing result for the same PU even on the same channel. By allowing the nodes to use the channel on which

the PU exists as long as their transmissions do not disturb the PU, the proposed MAC scheme fully utilizes the spectrum

access opportunity. To mitigate the hidden PU problem inherent to multichannel CR networks where the PU signal is

detectable only to some nodes, the proposed MAC scheme adjusts the sensing priorities of channels at each node with

the PU detection information of other nodes and also limits the transmission power of a CR node to the maximum

allowable power for guaranteeing the quality of service requirement of PU. The performance of the proposed MAC

A Cost Analysis Framework for NEMO Prefix Delegation-Based Schemes

A Novel MAC Scheme for Multichannel Cognitive Radio Ad Hoc Networks



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scheme is evaluated by using simulation. The simulation results show that the CR system with the proposed MAC

accomplishes good performance in throughput and packet delay, while protecting PUs properly.

Large Broadcasting is a fundamental operation in wireless networks and plays an important role in the communication

protocol design. In multihop wireless networks, however, interference at a node due to simultaneous transmissions from

its neighbors makes it nontrivial to design a minimum-latency broadcast algorithm, which is known to be NP-complete.

We present a simple 12-approximation algorithm for the one-to-all broadcast problem that improves all previously

known guarantees for this problem. We then consider the all-to-all broadcast problem where each node sends its own

message to all other nodes. For the all-to-all broadcast problem, we present two algorithms with approximation ratios of

20 and 34, improving the best result available in the literature. Finally, we report experimental evaluation of our

algorithms. Our studies indicate that our algorithms perform much better in practice than the worst-case guarantees

provided in the theoretical analysis and achieve up to 37 percent performance improvement over existing schemes.

WiFi continues to be a prime source of energy consumption in mobile devices. This paper observes that, despite a rich

body of research in WiFi energy management, there is room for improvement. Our key finding is that WiFi energy

optimizations have conventionally been designed with a single AP in mind. However, network contention among

different APs can dramatically increase a client's energy consumption. Each client may have to keep awake for long

durations before its own AP gets a chance to send it packets to it. As AP density increases, the waiting time inflates,

resulting in a proportional decrease in battery life. We design SleepWell, a system that achieves energy efficiency by

evading network contention. The APs regulate the sleeping window of their clients in a way that different APs are

active/inactive during nonoverlapping time windows. The solution is analogous to the common wisdom of going late to

office and coming back late, thereby avoiding the rush hours. We implement SleepWell on a testbed of eight Laptops

and nine Android phones, and evaluate it over a wide variety of scenarios and traffic patterns. Results show a median

gain of up to 2x when WiFi links are strong; when links are weak and the network density is high, the gains can be even

more.

This paper presents the design of a networked system for joint compression, rate control and error correction of video

over resource-constrained embedded devices based on the theory of Compressed Sensing (CS). The objective of this

work is to design a cross-layer system that jointly controls the video encoding rate, the transmission rate, and the

channel coding rate to maximize the received video quality. First, compressed sensing-based video encoding for

transmission over Wireless Multimedia Sensor Networks (WMSNs) is studied. It is shown that compressed sensing can

Avoiding the Rush Hours: WiFi Energy Management via Traffic Isolation

Compressed-Sensing-Enabled Video Streaming for Wireless Multimedia Sensor Networks

Approximation Algorithms for Data Broadcast in Wireless Networks



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overcome many of the current problems of video over WMSNs, primarily encoder complexity and low resiliency to

channel errors. A rate controller is then developed with the objective of maintaining fairness among different videos

while maximizing the received video quality. It is shown that the rate of Compressed Sensed Video (CSV) can be

predictably controlled by varying only the compressed sensing sampling rate. It is then shown that the developed rate

controller can be interpreted as the iterative solution to a convex optimization problem representing the optimization of

the rate allocation across the network. The error resiliency properties of compressed sensed images and videos are then

studied, and an optimal error detection and correction scheme is presented for video transmission over lossy channels.

Finally, the entire system is evaluated through simulation and test bed evaluation. The rate controller is shown to

outperform existing TCP-friendly rate control schemes in terms of both fairness and received video quality. The test bed

results show that the rates converge to stable values in real channels.

IEEE 802.15.4 standard specifies physical layer (PHY) and medium access control (MAC) sublayer protocols for low-rate

and low-power communication applications. In this protocol, every 4-bit symbol is encoded into a sequence of 32 chips

that are actually transmitted over the air. The 32 chips as a whole is also called a pseudonoise code (PN-Code). Due to

complex channel conditions such as attenuation and interference, the transmitted PN-Code will often be received with

some PN-Code chips corrupted. In this paper, we conduct a systematic analysis on these errors occurring at chip level.

We find that there are notable error patterns corresponding to different cases. We then show that recognizing these

patterns enables us to identify the channel condition in great details. We believe that understanding what happened to

the transmission in our way can potentially bring benefit to channel coding, routing, and error correction protocol

design. Finally, we propose Simple Rule, a simple yet effective method based on the chip error patterns to infer the link

condition with an accuracy of over 96 percent in our evaluations.

In this paper, we define an ad hoc network where multiple sources transmit packets to one destination as Converge-Cast

network. We will study the capacity delay tradeoffs assuming that n wireless nodes are deployed in a unit square. For

each session (the session is a dataflow from k different source nodes to 1 destination node), k nodes are randomly

selected as active sources and each transmits one packet to a particular destination node, which is also randomly

selected. We first consider the stationary case, where capacity is mainly discussed and delay is entirely dependent on

the average number of hops. We find that the per-node capacity is Θ (1/√(n log n)) (given nonnegative functions f(n) and

g(n): f(n) = O(g(n)) means there exist positive constants c and m such that f(n) ≤ cg(n) for all n ≥ m; f(n)= Ω (g(n)) means

there exist positive constants c and m such that f(n) ≥ cg(n) for all n ≥ m; f(n) = Θ (g(n)) means that both f(n) = Ω (g(n))

and f(n) = O(g(n)) hold), which is the same as that of unicast, presented in (Gupta and Kumar, 2000). Then, node mobility

is introduced to increase network capacity, for which our study is performed in two steps. The first step is to establish

the delay in single-session transmission. We find that the delay is Θ (n log k) under 1-hop strategy, and Θ (n log k/m)

Converge Cast: On the Capacity and Delay Tradeoffs

Chip Error Pattern Analysis in IEEE 802.15.4



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under 2-hop redundant strategy, where m denotes the number of replicas for each packet. The second step is to find

delay and capacity in multisession transmission. We reveal that the per-node capacity and delay for 2-hop

nonredundancy strategy are Θ (1) and Θ (n log k), respectively. The optimal delay is Θ (√(n log k)+k) with redundancy,

corresponding to a capacity of Θ (√((1/n log k) + (k/n log k)). Therefore, we obtain that the capacity delay tradeoff

satisfies delay/rate ≥ Θ (n log k) for both strategies.

Cellular text messaging services are increasingly being relied upon to disseminate critical information during

emergencies. Accordingly, a wide range of organizations including colleges and universities now partner with third-

party providers that promise to improve physical security by rapidly delivering such messages. Unfortunately, these

products do not work as advertised due to limitations of cellular infrastructure and therefore provide a false sense of

security to their users. In this paper, we perform the first extensive investigation and characterization of the limitations

of an Emergency Alert System (EAS) using text messages as a security incident response mechanism. We show

emergency alert systems built on text messaging not only can meet the 10 minute delivery requirement mandated by the

WARN Act, but also potentially cause other voice and SMS traffic to be blocked at rates upward of 80 percent. We then

show that our results are representative of reality by comparing them to a number of documented but not previously

understood failures. Finally, we analyze a targeted messaging mechanism as a means of efficiently using currently

deployed infrastructure and third-party EAS. In so doing, we demonstrate that this increasingly deployed security

infrastructure does not achieve its stated requirements for large populations.

Wireless sensor networks (WSNs) have recently emerged as a prominent technology for environmental monitoring and

hazardous event detection. Yet, their success depends considerably on their ability to ensure reliable event detection.

Such guarantees can be provided only if the target field monitored by a WSN does not contain coverage holes that are

not monitored by any sensor. Currently, the coverage hole detection solutions require accurate knowledge of the

sensors locations, which cannot be easily obtained, or they cannot provide guarantees on the coverage quality. In this

study, we address the challenge of designing an accurate k-coverage verification scheme, without using location

information, for a predefined k ≥ 1. To this end, we present two efficient, distributed, and localized k-coverage

verification schemes with proven guarantees on their coverage detection quality. Our simulations show that the

schemes accurately detect coverage holes of various sizes.

Characterizing the Security Implications of Third-Party Emergency Alert Systems over

Cellular Text Messaging Services

Coverage Verification without Location Information



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The legacy multicasting over IEEE 802.11-based WLANs has two well-known problems-poor reliability and low-rate

transmission. In the literature, various WLAN multicast protocols have been proposed in order to overcome these

problems. Existing multicast protocols, however, are not so efficient when they are used combining with the frame

aggregation scheme of IEEE 802.11n. In this paper, we propose a novel MAC-level multicast protocol for IEEE 802.11n,

named Reliable and Efficient Multicast Protocol (REMP). To enhance the reliability and efficiency of multicast services in

IEEE 802.11n WLANs, REMP enables selective retransmissions for erroneous multicast frames and efficient adjustments

of the modulation and coding scheme (MCS). In addition, we propose an extension of REMP, named scalable REMP (S-

REMP), for efficient delivery of scalable video over IEEE 802.11n WLANs. In S-REMP, different MCSs are assigned to

different layers of scalable video to guarantee the minimal video quality to all users while providing a higher video

quality to users exhibiting better channel conditions. Our simulation results show that REMP outperforms existing

multicast protocols for normal multicast traffic and S-REMP offers improved performance for scalable video streaming.

The WiMAX Forum has defined a two-tiered mobility management to minimize handover delay and packet loss. However,

it leads to another problem: When to perform ASN GW relocation? The standards only define the ASN GW relocation

procedures without specifying when the ASN GW relocation should be performed. It is left for vendors and operators to

develop their own proprietary solutions. In this paper, we propose an algorithm, which incorporates traditional

Admission Control (AC) and Wiener Process (WP)-based prediction algorithms to determine when to carry out ASN GW

relocation. We further develop an analytical model to analyze the proposed algorithm. Simulations are also conducted to

evaluate the performance of the proposed algorithm. The results show that the proposed algorithm can improve the

performance significantly in terms of blocking probability, dropping probability, average serving rate, and average

signaling overhead.

We consider a complex (i.e., nonlinear) road scenario where users aboard vehicles equipped with communication

interfaces are interested in downloading large files from road-side Access Points (APs). We investigate the possibility of

exploiting opportunistic encounters among mobile nodes so to augment the transfer rate experienced by vehicular

downloaders. To that end, we devise solutions for the selection of carriers and data chunks at the APs, and evaluate

them in real-world road topologies, under different AP deployment strategies. Through extensive simulations, we show

Design of Efficient Multicast Protocol for IEEE 802.11n WLANs and Cross-Layer

Optimization for Scalable Video Streaming

Design and Analysis of the Gateway Relocation and Admission Control Algorithm in

Mobile WiMAX Networks

Cooperative Download in Vehicular Environments



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that carry&forward transfers can significantly increase the download rate of vehicular users in urban/suburban

environments, and that such a result holds throughout diverse mobility scenarios, AP placements and network loads.

The WiMAX Forum has defined a two-tiered mobility management to minimize handover delay and packet loss. However,

it leads to another problem: When to perform ASN GW relocation? The standards only define the ASN GW relocation

procedures without specifying when the ASN GW relocation should be performed. It is left for vendors and operators to

develop their own proprietary solutions. In this paper, we propose an algorithm, which incorporates traditional

Admission Control (AC) and Wiener Process (WP)-based prediction algorithms to determine when to carry out ASN GW

relocation. We further develop an analytical model to analyze the proposed algorithm. Simulations are also conducted to

evaluate the performance of the proposed algorithm. The results show that the proposed algorithm can improve the

performance significantly in terms of blocking probability, dropping probability, average serving rate, and average

signaling overhead.

Recently, tuning the clear channel assessment (CCA) threshold in conjunction with power control has been considered

for improving the performance of WLANs. However, we show that, CCA tuning can be exploited by selfish nodes to

obtain an unfair share of the available bandwidth. Specifically, a selfish entity can manipulate the CCA threshold to

ignore ongoing transmissions; this increases the probability of accessing the medium and provides the entity a higher,

unfair share of the bandwidth. We experiment on our 802.11 testbed to characterize the effects of CCA tuning on both

isolated links and in 802.11 WLAN configurations. We focus on AP-client(s) configurations, proposing a novel approach

to detect this misbehavior. A misbehaving client is unlikely to recognize low power receptions as legitimate packets; by

intelligently sending low power probe messages, an AP can efficiently detect a misbehaving node. Our key contributions

are: 1) We are the first to quantify the impact of selfish CCA tuning via extensive experimentation on various 802.11

configurations. 2) We propose a lightweight scheme for detecting selfish nodes that inappropriately increase their CCAs.

3) We extensively evaluate our system on our testbed; its accuracy is 95 percent while the false positive rate is less than

5 percent.

Directional antennas can divide the transmission range into several sectors. Thus, through switching off sectors in

unnecessary directions in wireless networks, we can save bandwidth and energy consumption. In this paper, we will

study a directional virtual backbone (VB) in the network where directional antennas are used. When constructing a VB,

Energy-Efficient Cooperative Video Distribution with Statistical QoS Provisions over

Wireless Networks

Detection of Selfish Manipulation of Carrier Sensing in 802.11 Networks

Efficient Virtual Backbone Constructionwith Routing Cost Constraint in

WirelessNetworks Using Directional Antennas



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we will take routing and broadcasting into account since they are two common operations in wireless networks. Hence,

we will study a VB with guaranteed routing costs, named α Minimum rOuting Cost Directional VB (α-

MOC-DVB). Besides the properties of regular VBs, α-MOC-DVB also has a special constraint — for any

pair of nodes, there exists at least one path all intermediate directions on which must belong to α-MOC-DVB and

the number of intermediate directions on the path is smaller than α times that on the shortest path. We prove

that construction of a minimum α-MOC-DVB is an NP-hard problem in a general directed graph. A heuristic

algorithm is proposed and theoretical analysis is also discussed in the paper. Extensive simulations demonstrate that

our α-MOC-DVB is much more efficient in the sense of VB size and routing costs compared to other VBs.

We develop a distributed throughput-optimal power allocation algorithm in wireless networks. The study of this problem

has been limited due to the nonconvexity of the underlying optimization problems that prohibits an efficient solution

even in a centralized setting. By generalizing the randomization framework originally proposed for input queued

switches to SINR rate-based interference model, we characterize the throughput-optimality conditions that enable

efficient and distributed implementation. Using gossiping algorithm, we develop a distributed power allocation algorithm

that satisfies the optimality conditions, thereby achieving (nearly) 100 percent throughput. We illustrate the performance

of our power allocation solution through numerical simulation.

Visual capability introduced to Wireless Sensor Networks (WSNs) render many novel applications that would otherwise

be infeasible. However, unlike legacy WSNs which are commercially deployed in applications, visual sensor networks

create additional research problems that delays the real-world implementations. Conveying real-time video streams over

resource constrained sensor hardware remains to be a challenging task. As a remedy, we propose a fairness-based

approach to enhance the event reporting and detection performance of the Video Surveillance Sensor Networks. Instead

of achieving fairness only for flows or for nodes as investigated in the literature, we concentrate on the whole

application requirement. Accordingly, our Event-Based Fairness (EBF) scheme aims at fair resource allocation for the

application level messaging units called events. We identify the crucial network-wide resources as the in-queue

processing turn of the frames and the channel access opportunities of the nodes. We show that fair treatment of events,

as opposed to regular flow of frames, results in enhanced performance in terms of the number of frames reported per

event and the reporting latency. EBF is a robust mechanism that can be used as a stand-alone or as a complementary

method to other possible performance enhancement methods for video sensor networks implemented at other

communication layers.

Distributed Throughput Maximization in Wireless Networks via Random Power

Allocation

Efficient Rendezvous Algorithms for Mobility-Enabled Wireless Sensor Networks

Distributed and Online Fair Resource Management in Video Surveillance Sensor

Networks

Efficient Rendezvous Algorithms for Mobility-Enabled Wireless Sensor Networks



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Recent research shows that significant energy saving can be achieved in mobility-enabled wireless sensor networks

(WSNs) that visit sensor nodes and collect data from them via short-range communications. However, a major

performance bottleneck of such WSNs is the significantly increased latency in data collection due to the low movement

speed of mobile base stations. To address this issue, we propose a rendezvous-based data collection approach in which

a subset of nodes serve as rendezvous points that buffer and aggregate data originated from sources and transfer to the

base station when it arrives. This approach combines the advantages of controlled mobility and in-network data caching

and can achieve a desirable balance between network energy saving and data collection delay. We propose efficient

rendezvous design algorithms with provable performance bounds for mobile base stations with variable and fixed

tracks, respectively. The effectiveness of our approach is validated through both theoretical analysis and extensive

simulations.

Scalable video transmission over a network is easily adaptable to different types of mobile experiencing different

network conditions. However the transmission of differentiated video packets in an error-prone wireless environment

remains problematic. We propose and analyze a cross-layer error control scheme that exploits priority-aware block

interleaving (PBI) in the MAC layer for video broadcasting in CDMA2000 systems. The PBI scheme allocates a higher

priority to protecting the data which are more critical to the decoding of a video stream, and therefore has more effect on

picture quality in the application layer. The use of Reed-Solomon coding in conjunction with PBI in the MAC layer can

handle error bursts more effectively if its implementation takes account of underlying error distributions in the physical

layer, and differentiates between different types of video packets in the application layer. We also calculate the

maximum jitter from the variability of the Reed-Solomon decoding delay and determine the size of jitter buffer needed to

prevent interruptions due to buffer underrun. Simulations demonstrate the extent to which we can improve the perceived

quality of scalable video.

Distributed Information SHaring (DISH) is a new cooperative approach to designing multichannel MAC protocols. It aids

nodes in their decision making processes by compensating for their missing information via information sharing

through neighboring nodes. This approach was recently shown to significantly boost the throughput of multichannel

MAC protocols. However, a critical issue for ad hoc communication devices, viz. energy efficiency, has yet to be

addressed. In this paper, we address this issue by developing simple solutions that reduce the energy consumption

without compromising the throughput performance and meanwhile maximize cost efficiency. We propose two energy-

Distributed Throughput Maximization in Wireless Networks via Random Power

Allocation

Energy-Efficient Strategies for Cooperative Multichannel MAC Protocols



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efficient strategies: in-situ energy conscious DISH, which uses existing nodes only, and altruistic DISH, which requires

additional nodes called altruists. We compare five protocols with respect to these strategies and identify altruistic DISH

to be the right choice in general: it 1) conserves 40-80 percent of energy, 2) maintains the throughput advantage, and 3)

more than doubles the cost efficiency compared to protocols without this strategy. On the other hand, our study also

shows that in-situ energy conscious DISH is suitable only in certain limited scenarios.

Traffic monitoring using probe vehicles with GPS receivers promises significant improvements in cost, coverage, and

accuracy over dedicated infrastructure systems. Current approaches, however, raise privacy concerns because they

require participants to reveal their positions to an external traffic monitoring server. To address this challenge, we

describe a system based on virtual trip lines and an associated cloaking technique, followed by another system design

in which we relax the privacy requirements to maximize the accuracy of real-time traffic estimation. We introduce virtual

trip lines which are geographic markers that indicate where vehicles should provide speed updates. These markers are

placed to avoid specific privacy sensitive locations. They also allow aggregating and cloaking several location updates

based on trip line identifiers, without knowing the actual geographic locations of these trip lines. Thus, they facilitate the

design of a distributed architecture, in which no single entity has a complete knowledge of probe identities and fine-

grained location information. We have implemented the system with GPS smartphone clients and conducted a

controlled experiment with 100 phone-equipped drivers circling a highway segment, which was later extended into a

year-long public deployment.

Tracking of people via active badges is important for location-aware computing and for security applications. However,

the human body has a major effect on the antenna gain pattern of the device that the person is wearing. In this paper,

the gain pattern due to the effect of the human body is experimentally measured and represented by a first-order

directional gain pattern model. A method is presented to estimate the model parameters from multiple received signal

strength (RSS) measurements. An alternating gain and position estimation (AGAPE) algorithm is proposed to jointly

estimate the orientation and the position of the badge using RSS measurements at known-position anchor nodes. Lower

bounds on mean squared error (MSE) and experimental results are presented that both show that the accuracy of

position estimates can be greatly improved by including orientation estimates in the localization system. Next, we

propose a new tracking filter that accepts orientation estimates as input, which we call the orientation-enhanced

extended Kalman filter (OE-EKF), which improves tracking accuracy in active RFID tracking systems.

Enhancing Privacy and Accuracy in Probe Vehicle-Based Traffic Monitoring via Virtual

Trip Lines

Directed by Directionality: Benefiting from the Gain Pattern of Active RFID Badges



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Traffic Faulty components in a network need to be localized and repaired to sustain the health of the network. In this

paper, we propose a novel approach that carefully combines active and passive measurements to localize faults in

wireless sensor networks. More specifically, we formulate a problem of optimal sequential testing guided by end-to-end

data. This problem determines an optimal testing sequence of network components based on end-to-end data in sensor

networks to minimize expected testing cost. We prove that this problem is NP-hard, and propose a recursive approach

to solve it. This approach leads to a polynomial-time optimal algorithm for line topologies while requiring exponential

running time for general topologies. We further develop two polynomial-time heuristic schemes that are applicable to

general topologies. Extensive simulation shows that our heuristic schemes only require testing a very small set of

network components to localize and repair all faults in the network. Our approach is superior to using active and passive

measurements in isolation. It also outperforms the state-of-the-art approaches that localize and repair all faults in a

network.

Faulty components in a network need to be localized and repaired to sustain the health of the network. In this paper, we

propose a novel approach that carefully combines active and passive measurements to localize faults in wireless sensor

networks. More specifically, we formulate a problem of optimal sequential testing guided by end-to-end data. This

problem determines an optimal testing sequence of network components based on end-to-end data in sensor networks

to minimize expected testing cost. We prove that this problem is NP-hard, and propose a recursive approach to solve it.

This approach leads to a polynomial-time optimal algorithm for line topologies while requiring exponential running time

for general topologies. We further develop two polynomial-time heuristic schemes that are applicable to general

topologies. Extensive simulation shows that our heuristic schemes only require testing a very small set of network

components to localize and repair all faults in the network. Our approach is superior to using active and passive

measurements in isolation. It also outperforms the state-of-the-art approaches that localize and repair all faults in a

network.

We propose a method for estimating parameters of multiple target objects by using networked binary sensors whose

locations are unknown. These target objects may have different parameters, such as size and perimeter length. Each

sensors, which is incapable of monitoring the target object's parameters, sends only binary data describing whether or

not it detects target objects coming into, moving around, or leaving the sensing area at every moment. We previously

developed a parameter estimation method for a single target object. However, a straight-forward extension of this

method is not applicable for estimating multiple heterogeneous target objects. This is because a networked binary

Fault Localization Using Passive End-to-End Measurements and Sequential Testing for

Wireless Sensor Networks

FESCIM: Fair, Efficient, and Secure Cooperation Incentive Mechanism for Multi-hop

Cellular Networks

Estimating Parameters of Multiple Heterogeneous Target Objects Using Composite

Sensor Nodes



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sensor at an unknown location cannot provide information that distinguishes individual target objects, but it can provide

information on the total perimeter length and size of multiple target objects. Therefore, we propose composite sensor

nodes with multiple sensors in a predetermined layout for obtaining additional information for estimating the parameter

of each target object. As an example of a composite sensor node, we consider a two-sensor composite sensor node,

which consists of two sensors, one at each of the two end points of a line segment of known length. For the two-sensor

composite sensor node, measures are derived such as the two sensors detecting target objects. These derived

measures are the basis for identifying the shape of each target object among a given set of categories (for example,

disks and rectangles) and estimating parameters such as the radius and lengths of two sides of each target object.

Numerical examples demonstrate that networked composite sensor nodes consisting of two binary sensors enable us to

estimate the parameters of target objects.

In a mobile ad hoc network, the mobility and resource constraints of mobile nodes may lead to network partitioning or

performance degradation. Several data replication techniques have been proposed to minimize performance

degradation. Most of them assume that all mobile nodes collaborate fully in terms of sharing their memory space. In

reality, however, some nodes may selfishly decide only to cooperate partially, or not at all, with other nodes. These

selfish nodes could then reduce the overall data accessibility in the network. In this paper, we examine the impact of

selfish nodes in a mobile ad hoc network from the perspective of replica allocation. We term this selfish replica

allocation. In particular, we develop a selfish node detection algorithm that considers partial selfishness and novel

replica allocation techniques to properly cope with selfish replica allocation. The conducted simulations demonstrate

the proposed approach outperforms traditional cooperative replica allocation techniques in terms of data accessibility,

communication cost, and average query delay.

We investigate the following fundamental question-how fast can information be collected from a wireless sensor

network organized as tree? To address this, we explore and evaluate a number of different techniques using realistic

simulation models under the many-to-one communication paradigm known as convergecast. We first consider time

scheduling on a single frequency channel with the aim of minimizing the number of time slots required (schedule length)

to complete a convergecast. Next, we combine scheduling with transmission power control to mitigate the effects of

interference, and show that while power control helps in reducing the schedule length under a single frequency,

scheduling transmissions using multiple frequencies is more efficient. We give lower bounds on the schedule length

when interference is completely eliminated, and propose algorithms that achieve these bounds. We also evaluate the

performance of various channel assignment methods and find empirically that for moderate size networks of about 100

nodes, the use of multifrequency scheduling can suffice to eliminate most of the interference. Then, the data collection

rate no longer remains limited by interference but by the topology of the routing tree. To this end, we construct degree-

Handling Selfishness in Replica Allocation over a Mobile Ad Hoc Network

Fast Data Collection in Tree-Based Wireless Sensor Networks



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constrained spanning trees and capacitated minimal spanning trees, and show significant improvement in scheduling

performance over different deployment densities. Lastly, we evaluate the impact of different interference and channel

models on the schedule length.

In RFID systems, far field passive tags send information using back scattering. The signal level is typically very small, so

channel error during transmission may occur frequently. Due to channel error, performance of RFID tag identification

under error-prone channel is degraded compared to that under error-free channel. In this paper, we propose a novel

error resilient estimation and adaptive binary selection to overcome the problem of channel errors. Our proposed error

resilient estimation algorithm can estimate the number of tags and the channel state accurately regardless of frame

errors. And our proposed adaptive binary selection reduces the idle slots caused by frame errors. Performance analysis

and simulation results show that the proposed algorithm consumes up to 20% less time slots than the binary tree

protocol and dynamic framed slotted ALOHA (DFSA) in various bit error rate (BER) conditions.

The technology of Radio Frequency IDentification (RFID) enables many applications that rely on passive, battery-less

wireless devices. If a RFID reader needs to gather the ID from multiple tags in its range, then it needs to run an

anticollision protocol. Due to errors on the wireless link, a single reader session, which contains one full execution of

the anticollision protocol, may not be sufficient to retrieve the ID of all tags. This problem can be mitigated by running

multiple, redundant reader sessions and use the statistical relationship between these sessions. On the other hand,

each session is time consuming and therefore the number of sessions should be kept minimal. We optimize the process

of running multiple reader sessions, by allowing only some of the tags already discovered to reply in subsequent reader

sessions. The estimation procedure is integrated with an actual tree-based anticollision protocol, and numerical results

show that the reliable tag resolution algorithm attain high speed of protocol execution, while not sacrificing the

reliability of the estimators used to assess the probability of missing tags.

In This paper presents positioning algorithms for cellular network-based mobile tracking in severe non-line-of-sight

(NLOS) propagation scenarios. The aim of the algorithms is to enhance positional accuracy of network-based

Error Resilient Estimation and Adaptive Binary Selection for Fast and Reliable

Identification of RFID Tags in Error-Prone Channel

Fast Capture—Recapture Approach for Mitigating the Problem of Missing RFID Tags

Geometry and Motion-Based Positioning Algorithms for Mobile Tracking in NLOS

Environments



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positioning systems when the GPS receiver does not perform well due to the hostile environment. Two positioning

methods with NLOS mitigation are proposed. Constrained optimization is utilized to minimize the cost function which

takes account of the NLOS error. Mobile velocity and heading angle information is exploited to greatly enhance position

accuracy. It is observed through simulation that the proposed methods significantly outperform other cellular network

based positioning algorithms. Further, the exact expressions of the CRLB are derived when the distance measurement

error is the sum of an exponential and a Gaussian variable. RFID systems, far field passive tags send information using

back scattering. The signal level is typically very small, so channel error during transmission may occur frequently. Due

to channel error, performance of RFID tag identification under error-prone channel is degraded compared to that under

error-free channel. In this paper, we propose a novel error resilient estimation and adaptive binary selection to overcome

the problem of channel errors. Our proposed error resilient estimation algorithm can estimate the number of tags and

the channel state accurately regardless of frame errors. And our proposed adaptive binary selection reduces the idle

slots caused by frame errors. Performance analysis and simulation results show that the proposed algorithm consumes

up to 20% less time slots than the binary tree protocol and dynamic framed slotted ALOHA (DFSA) in various bit error

rate (BER) conditions.

This paper presents positioning algorithms for cellular network-based mobile tracking in severe non-line-of-sight (NLOS)

propagation scenarios. The aim of the algorithms is to enhance positional accuracy of network-based positioning

systems when the GPS receiver does not perform well due to the hostile environment. Two positioning methods with

NLOS mitigation are proposed. Constrained optimization is utilized to minimize the cost function which takes account of

the NLOS error. Mobile velocity and heading angle information is exploited to greatly enhance position accuracy. It is

observed through simulation that the proposed methods significantly outperform other cellular network based

positioning algorithms. Further, the exact expressions of the CRLB are derived when the distance measurement error is

the sum of an exponential and a Gaussian variable.

In this paper, we consider the implications of spectrum heterogeneity on connectivity and routing in a Cognitive Radio

Ad Hoc Network (CRAHN). We study the Laplacian spectrum of the CRAHN graph when the activity of primary users is

considered. We introduce the cognitive algebraic connectivity, i.e., the second smallest eigenvalue of the Laplacian of a

graph, in a cognitive scenario. Throughout this notion we provide a methodology to evaluate the connectivity of

CRAHNs and consequently introduce a utility function that is shown to be effective in capturing key characteristics of

CRAHN paths. This model provides a unique metric that captures network connectivity, path length, and impact of

Local Broadcast Algorithms in Wireless Ad Hoc Networks: Reducing the Number of

Transmissions

Leveraging the Algebraic Connectivity of a Cognitive Network for Routing Design



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primary users. Moreover, the proposed metric penalizes paths where spectrum band switchings are highly probable. We

design all the components of our routing framework, named Gymkhana, and we present a twofold performance

verification: one from a topological perspective to show all the potentialities of the proposed routing approach, and the

other considering network traffic to evaluate the performance in terms of end-to-end delay and packet delivery ratio.

In this paper, we present local distributed algorithms for constructing spanners in wireless sensor networks modeled as

unit ball graphs (shortly UBGs) and quasi-unit ball graphs (shortly quasi-UBGs), in the 3D euclidean space. Our first

contribution is a local distributed algorithm that, given a UBG U and a parameter alpha < pi/3, constructs a sparse

spanner of U with stretch factor 1/(1-2sin {(alpha/2)}), improving the previous upper bound of 1/(1-alpha ) by Althöfer et

al. which is applicable only when alpha < 1/(1+2sqrt{2}) < pi/3. The second contribution of this paper is in presenting the

first local distributed algorithm for the construction of bounded-degree lightweight spanners of UBGs and quasi-UBGs.

The simulation results we obtained show that, empirically, the weight and the stretch factor of the spanners, and the

locality of the algorithms, are much better than the theoretical upper bounds proved in this paper.

Context prediction is the task of inferring information about the progression of an observed context time series based

on its previous behavior. Prediction methods can be applied at several abstraction levels in the context processing

chain. In a theoretical analysis as well as by means of experiments we show that the nature of the input data, the quality

of the output, and finally the flow of processing operations used to make a prediction, are correlated. A comprehensive

discussion of basic concepts in context prediction domains and a study on the effects of the context abstraction level

on the context prediction accuracy in context prediction scenarios is provided. We develop a set of formulae that link

scenario-dependent parameters to a probability for the context prediction accuracy. It is demonstrated that the results

achieved in our theoretical analysis can also be confirmed in simulations as well as in experimental studies.

Wireless Mesh Network (WMN) has become an important edge network to provide Internet access to remote areas and

wireless connections in a metropolitan scale. In this paper, we study the problem of identifying the maximum available

Local Construction of Spanners in the 3D Space

Investigation of Context Prediction Accuracy for Different Context Abstraction Levels

Hop-by-Hop Routing in Wireless Mesh Networks with Bandwidth Guarantees



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bandwidth path, a fundamental issue in supporting quality-of-service in WMNs. Due to interference among links,

bandwidth, a well-known bottleneck metric in wired networks, is neither concave nor additive in wireless networks. We

propose a new path weight which captures the available path bandwidth information. We formally prove that our hop-by-

hop routing protocol based on the new path weight satisfies the consistency and loop-freeness requirements. The

consistency property guarantees that each node makes a proper packet forwarding decision, so that a data packet does

traverse over the intended path. Our extensive simulation experiments also show that our proposed path weight

outperforms existing path metrics in identifying high-throughput paths.









We revisit the problem of computing the path with the minimum cost in terms of the expected number of link layer

transmissions (including retransmissions) in wireless mesh networks. Unlike previous efforts, such as the popular ETX,

we account for the fact that MAC protocols (including the IEEE 802.11 MAC) incorporate a finite number of transmission

attempts per packet. This in turn leads to our key observation: the performance of a path depends not only on the

number of the links on the path and the quality of its links, but also, on the relative positions of the links on the path.

Based on this observation, we propose ETOP, a path metric that accurately captures the expected number of link layer

transmissions required for reliable end-to-end packet delivery. We analytically compute ETOP, which is not trivial, since

ETOP is a noncommutative function of the link success probabilities. Although ETOP is a more involved metric, we

show that the problem of computing paths with the minimum ETOP cost can be solved by a greedy algorithm. We

implement and evaluate a routing approach based on ETOP on a 25-node indoor mesh network. Our experiments show

that the path selection with ETOP consistently results in superior TCP goodput (by over 50 percent in many cases)

compared to path selection based on ETX. We also perform an in-depth analysis of the measurements to better

understand why the paths selected by ETOP improve the TCP performance.


Link Positions Matter: A Non-commutative Routing Metric for Wireless Mesh Networks



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In recent years, there has been a significant amount of work done in developing low-complexity scheduling schemes to

achieve high performance in multihop wireless networks. A centralized suboptimal scheduling policy, called Greedy

Maximal Scheduling (GMS) is a good candidate because its empirically observed performance is close to optimal in a

variety of network settings. However, its distributed realization requires high complexity, which becomes a major

obstacle for practical implementation. In this paper, we develop simple distributed greedy algorithms for scheduling in

multihop wireless networks. We reduce the complexity by relaxing the global ordering requirement of GMS, up to near

zero. Simulation results show that the new algorithms approximate the performance of GMS, and outperform the state-

of-the-art distributed scheduling policies.

It is widely evidenced that location has a significant influence on the actual bandwidth that can be expected from

Wireless Wide Area Networks (WWANs), e.g., 3G. Because a fast-moving vehicle continuously changes its location,

vehicular mobile computing is confronted with the possibility of significant variations in available network bandwidth.

While it is difficult for providers to eliminate bandwidth disparity over a large service area, it may be possible to map

network bandwidth to the road network through repeated measurements. In this paper, we report results of an extensive

measurement campaign to demonstrate the viability of such bandwidth maps. We show how bandwidth maps can be

interfaced with adaptive multimedia servers and the emerging vehicular communication systems that use on-board

mobile routers to deliver Internet services to the passengers. Using simulation experiments driven by our measurement

data, we quantify the improvement in Quality of Service (QoS) that can be achieved by taking advantage of the

geographical knowledge of bandwidth provided by the bandwidth maps. We find that our approach reduces the

frequency of disruptions in perceived QoS for both audio and video applications in high-speed vehicular mobility by

several orders of magnitude.

Emerging media overlay networks for wireless applications aim at delivering Variable Bit Rate (VBR) encoded media

contents to nomadic end users by exploiting the (fading-impaired and time-varying) access capacity offered by the "last-

hop” wireless channel. In this application scenario, a still open question concerns the closed-form design of control

Local Greedy Approximation for Scheduling in Multihop Wireless Networks

Improving QoS in High-Speed Mobility Using Bandwidth Maps

Jointly Optimal Source-Flow, Transmit-Power, and Sending-Rate Control for Maximum-

Throughput Delivery of VBR Traffic over Faded Links



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policies that maximize the average throughput sent over the wireless last hop, under constraints on the maximum

connection bandwidth available at the Application (APP) layer, the queue capacity available at the Data Link (DL) layer,

and the average and peak energies sustained by the Physical (PHY) layer. The approach we follow relies on the

maximization on a per-slot basis of the throughput averaged over the fading statistic and conditioned on the queue

state, without resorting to cumbersome iterative algorithms. The resulting optimal controller operates in a cross-layer

fashion that involves the APP, DL, and PHY layers of the underlying protocol stack. Finally, we develop the operating

conditions allowing the proposed controller also to maximize the unconditional average throughput (i.e., the throughput

averaged over both queue and channel-state statistics). The carried out numerical tests give insight into the connection

bandwidth-versus-queue delay trade-off achieved by the optimal controller.

Instant messaging (IM) services enable real-time text and multimedia exchange and online presence awareness. Users

typically log onto instant messaging services persistently to discover available friends and also to be discovered.

However, our analysis shows that the frequency exchange of presence information incurs massive power consumption

to mobile devices over cellular or wireless local area networks. Such power consumption penalty can render persistent-

instant messaging infeasible for battery-powered mobile devices. In this paper, we propose several solutions to mitigate

the power consumption problem. By reducing the network access and keeping mobile devices in the sleep mode as

much as possible, these solutions achieve significant power saving. The power consumption of the proposed solutions

is derived analytically in this paper and the proposed solutions are implemented using a Jabber-based architecture.

Actual power measurement results show that the power consumption of the proposed solutions agrees well with our

analysis, and significant power saving can be achieved on mobile handsets with our low power consumption solutions

implemented.

IEEE 802.16 OFDMA systems have gained much attention for their ability to support high transmission rates and

broadband access services. For multiuser environments, IEEE 802.16 OFDMA systems require a resource allocation

algorithm to use the limited downlink resource efficiently. The IEEE 802.16 standard defines that resource allocation

should be performed with a rectangle region of slots, called a burst. However, the standard does not specify how to

construct bursts. In this paper, we propose a heuristic burst construction algorithm, called HuB, to improve the

downlink capacity in IEEE 802.16 OFDMA systems. To increase the downlink capacity, during burst constructions HuB

reduces resource wastage by considering padded slots and unused slots and reduces resource usage by considering

the power boosting possibility. For simple burst constructions, HuB makes a HuB-tree, in which a node represents an

Low Power Consumption Solutions for Mobile Instant Messaging

Heuristic Burst Construction Algorithm for Improving Downlink Capacity in IEEE

802.16 OFDMA Systems



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available downlink resource and edges of a node represent a burst rectangle region. Thus, making child nodes of a

parent node is the same as constructing a burst in a given downlink resource. We analyzed the proposed algorithm and

performed simulations to compare the performance of the proposed algorithm with existing algorithms. Our simulation

study results show that HuB shows improved downlink capacity over existing algorithms.









Dynamic Spectrum Access can enable a secondary user in a cognitive network to access unused spectrum, or

whitespace, found between primary user transmissions in a wireless network. The key design objective for a secondary

user access strategy is to "scavenge” the maximum amount of spatio-temporally fragmented whitespace while limiting

the amount of disruption caused to the primary users. In this paper, we first measure and analyze the whitespace

profiles of an 802.11 network (using ns-2 simulation) and a non-802.11 (CSMA)-based network (developed on TelosB

Motes). Then we propose two novel secondary user access strategies, which are based on measurement and statistical

modeling of the whitespace as perceived by the secondary users. Afterward, we perform simulation experiments to

validate the effectiveness of the proposed access strategies under single and multiple secondary user scenarios, and

evaluate their performance numerically using the developed analytical expressions. The results show that the proposed

access strategies are able to consistently scavenge between 90 and 96 percent of the available whitespace capacity,

while keeping the primary users disruption less than 5 percent.


Measurement-Based Bandwidth Scavenging in Wireless Networks

Mobile Ad Hoc Nanonetworks with Collision-Based Molecular Communication



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Context Recent developments in nanotechnology have enabled the fabrication of nanomachines with very limited

sensing, computation, communication, and action capabilities. The network of communicating nanomachines is

envisaged as nanonetworks that are designed to accomplish complex tasks such as drug delivery and health

monitoring. For the realization of future nanonetworks, it is essential to develop novel and efficient communication and

networking paradigms. In this paper, the first step toward designing a mobile ad hoc molecular nanonetwork (MAMNET)

with electrochemical communication is taken. MAMNET consists of mobile nanomachines and infostations that share

nanoscale information using electrochemical communication whenever they have a physical contact with each other. In

MAMNET, the intermittent connectivity introduced by the mobility of nanomachines and infostations is a critical issue to

be addressed. An analytical framework that incorporates the effect of mobility into the performance of electrochemical

communication among nanomachines is presented. Using the analytical model, numerical analysis for the performance

evaluation of MAMNET is obtained. Results reveal that MAMNET achieves adequately high throughput to enable frontier

nanonetwork applications with acceptable communication latency.

Wireless sensor networks are often battery-powered, and hence extending the network lifetime is one of the primary

concerns in the ubiquitous deployment of wireless sensor networks. One approach to efficiently utilize the limited

energy supplies of the sensors is to have the medium access control (MAC) protocol duty-cycle the sensors,

periodically putting the sensors to sleep and waking them up to reduce idle listening, which is energy intensive. Among

duty-cycled MAC protocols, some protocols are synchronized so that nodes wake up at the same time in each cycle, and

other protocols are asynchronous, where nodes have arbitrary offsets to start their cycles. For protocol designers, it is

important to understand which type of duty-cycled MAC protocol should be chosen (synchronized or asynchronous), as

well as what values should be assigned to the protocol parameters under a given network scenario in order to achieve a

desirable performance for throughput, delay, or energy consumption. However, previous work to analyze the

performance of different duty-cycled MAC protocols is either protocol-specific, or limited to one aspect of the

performance metric. In this paper, we propose a Markov queuing model to analyze the throughput, delay, and energy

consumption of both synchronized and asynchronous duty-cycled MAC protocols with applications to S-MAC and X-

MAC. Our contributions include: 1) proposing a Markov queuing model to describe the queuing behavior of both

synchronous and asynchronous duty-cycled nodes, 2) modeling the queue dynamics and the stationary probability of

packet transmissions for S-MAC, a synchronized duty-cycled MAC protocol, to analyze its performance, 3) modeling the

queue dynamics and the stationary probability of packet transmissions for X-MAC, an asynchronous duty-cycled MAC

protocol, to analyze its performance, 4) providing comprehensive performance estimation and comparison for different

duty-cycled MAC protocols, and 5) providing flexibility to - radeoff different performance metrics by optimizing the

protocol parameters. Our model results are validated by comparing with NS-2 and Matlab simulations.

Modeling and Performance Analysis for Duty-Cycled MAC Protocols with Applications

to S-MAC and X-MAC



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Context Dynamic spectrum access has been a subject of extensive study in recent years. The increasing volume of

literatures calls for a deeper understanding of the characteristics of current spectrum utilization. In this paper, we

present a detailed spectrum measurement study, with data collected in the 20 MHz to 3 GHz spectrum band and at four

locations concurrently in Guangdong province of China. We examine the statistics of the collected data, including

channel vacancy statistics, channel utilization within each individual wireless service, and the spectral and spatial

correlation of these measures. Main findings include that the channel vacancy durations follow an exponential-like

distribution, but are not independently distributed over time, and that significant spectral and spatial correlations are

found between channels of the same service. We then exploit such spectrum correlation to develop a 2D frequent

pattern mining algorithm that can predict channel availability based on past observations with considerable accuracy.

This paper presents a framework that develops algorithms for solving combined locational and multihop routing

optimization problems. The objective is to determine resource node locations in a multiagent network and to specify the

multihop routes from each agent to a common destination through a network of resource nodes that minimize total

communication cost. These problems are computationally complex (NP-hard) where the cost functions are riddled with

multiple minima. Algorithms based on Maximum Entropy Principle, which guarantee local minima and are heuristically

designed to seek the global minimum are presented. These algorithms accommodate practical constraints on resource

nodes as well as on the routing network architectures. Simulation results show that the multihop routes and resource

locations allocated by these algorithms achieve lower costs (as low as 47 percent) than those algorithms where

resource locational optimization is done without multihop routing or where the locational and routing optimization

objectives are separated. The enabling feature of these algorithms is accommodating problems with resource

constraints which is demonstrated through simulations. .

The pervasive adoption of IEEE 802.11 radios in the past decade has made possible for the easy Internet access from a

vehicle, notably drive-thru Internet. Originally designed for the static indoor applications, the throughput performance of

IEEE 802.11 in the outdoor vehicular environment is, however, still unclear especially when a large number of fast-

moving users transmitting simultaneously. In this paper, we investigate the performance of IEEE 802.11 DCF in the

highly mobile vehicular networks. We first propose a simple yet accurate analytical model to evaluate the throughput of

DCF in the large scale drive-thru Internet scenario. Our model incorporates the high-node mobility with the modeling of

Mining Spectrum Usage Data: A Large-Scale Spectrum Measurement Study

Maximum Entropy Principle-Based Algorithm for Simultaneous Resource Location and

Multihop Routing in Multiagent Networks

MAC in Motion: Impact of Mobility on the MAC of Drive-Thru Internet



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DCF and unveils the impacts of mobility (characterized by node velocity and moving directions) on the resultant

throughput. Based on the model, we show that the throughput of DCF will be reduced with increasing node velocity due

to the mismatch between the MAC and the transient high-throughput connectivity of vehicles. We then propose several

enhancement schemes to adaptively adjust the MAC in tune with the node mobility. Extensive simulations are carried

out to validate the accuracy of the developed analytical model and the effectiveness of the proposed enhancement

schemes.

3G networks are currently overloaded, due to the increasing popularity of various applications for smartphones.

Offloading mobile data traffic through opportunistic communications is a promising solution to partially solve this

problem, because there is almost no monetary cost for it. We propose to exploit opportunistic communications to

facilitate information dissemination in the emerging Mobile Social Networks (MoSoNets) and thus reduce the amount of

mobile data traffic. As a case study, we investigate the target-set selection problem for information delivery. In

particular, we study how to select the target set with only k users, such that we can minimize the mobile data traffic over

cellular networks. We propose three algorithms, called Greedy, Heuristic, and Random, for this problem and evaluate

their performance through an extensive trace-driven simulation study. Our simulation results verify the efficiency of

these algorithms for both synthetic and real-world mobility traces. For example, the Heuristic algorithm can offload

mobile data traffic by up to 73.66 percent for a real-world mobility trace. Moreover, to investigate the feasibility of

opportunistic communications for mobile phones, we implement a proof-of-concept prototype, called Opp-off, on Nokia

N900 smartphones, which utilizes their Bluetooth interface for device/service discovery and content transfer.

This paper describes the design and implementation of a file system-based distributed authoring system for campus-

wide workgroups. We focus on documents for which changes by different group members are harder to automatically

reconcile into a single version. Prior approaches relied on using group-aware editors. Others built collaborative

middleware that allowed the group members to use traditional authoring tools. These approaches relied on an ability to

automatically detect conflicting updates. They also operated on specific document types. Instead, our system relies on

users to moderate and reconcile updates by other group members. Our file system-based approach also allows group

members to modify any document type. We maintain one updateable copy of the shared content on each group

member's node. We also hoard read-only copies of each of these updateable copies in any interested group member's

node. All these copies are propagated to other group members at a rate that is solely dictated by the wireless user

availability. The various copies are reconciled using the moderation operation; each group member manually

incorporates updates from all the other group members into their own copy. The various document versions eventually

Mobile Data Offloading through Opportunistic Communications and Social

Participation

Moderated Group Authoring System for Campus-Wide Workgroups



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converge into a single version through successive moderation operations. The system assists with this convergence

process by using the made-with knowledge of all causal file system reads of contents from other replicas. An analysis

using a long-term wireless user availability traces from a university shows the strength of our asynchronous and

distributed update propagation mechanism. Our user space file system prototype exhibits acceptable file system

performance. A subjective evaluation showed that the moderation operation was intuitive for students.

This In this paper, we extend an information-theoretic approach for characterizing the minimum cost of tracking the

motion state information, such as locations and velocities, of nodes in dynamic networks. A rate-distortion formulation

is proposed to solve this minimum-cost motion-tracking problem, where the minimum cost is the minimum information

rate required to identify the network state at a sequence of tracking time instants within a certain distortion bound. The

formulation is applicable to various mobility models, distortion criteria, and stochastic sequences of tracking time

instants and hence is general. Under Brownian motion and Gauss-Markov mobility models, we evaluate lower bounds on

the information rate of tracking the motion state information of nodes, where the motion state of a node is 1) the node's

locations only, or 2) both its locations and velocities. We apply the obtained results to analyze the geographic routing

overhead in mobile ad hoc networks. We present the minimum overhead incurred by maintaining the geographic

information of nodes in terms of node mobility, packet arrival process, and distortion bounds. This leads to precise

characterizations of the observation that given certain state-distortion allowance, protocols aimed at tracking motion

state information may not scale beyond a certain level of node mobility.

Broadcast is one of the most fundamental services in wireless sensor networks (WSNs). It facilitates sensor nodes to

propagate messages across the whole network, serving a wide range of higher level operations and thus being critical to

the overall network design. A distinct feature of WSNs is that many nodes alternate between active and dormant states,

so as to conserve energy and extend the network lifetime. Unfortunately, the impact of such cycles has been largely

ignored in existing broadcast implementations that adopt the common assumption of all nodes being active all over the

time. In this paper, we revisit the broadcast problem with active/dormant cycles. We show strong evidence that

conventional broadcast approaches will suffer from severe performance degradation, and, under low duty cycles, they

could easily fail to cover the whole network in an acceptable time frame. To this end, we remodel the broadcast problem

in this new context, seeking a balance between efficiency and latency with coverage guarantees. We demonstrate that

this problem can be translated into a graph equivalence, and develop a centralized optimal solution. It provides a

valuable benchmark for assessing diverse duty-cycle-aware broadcast strategies. We then extend it to an efficient and

On the Cost of Knowledge of Mobility in Dynamic Networks:An Information-Theoretic

Approach

On Reliable Broadcast in Low Duty-Cycle Wireless Sensor Networks



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scalable distributed implementation, which relies on local information and operations only, with built-in loss

compensation mechanisms. The performance of our solution is evaluated under diverse network configurations. The

results suggest that our distributed solution is close to the lower bounds of both time and forwarding costs, and it well

resists to the wireless loss with good scalability on the network size and density. In addition, it enables flexible control

toward the quality of broadcast coverage.

We investigate the communication range of the nodes necessary for network connectivity, which we call bidirectional

connectivity, in a simple setting. Unlike in most of existing studies, however, the locations or mobilities of the nodes

may be correlated through group mobility: nodes are broken into groups, with each group comprising the same number

of nodes, and lie on a unit circle. The locations of the nodes in the same group are not mutually independent, but are

instead conditionally independent given the location of the group. We examine the distribution of the smallest

communication range needed for bidirectional connectivity, called the critical transmission range (CTR), when both the

number of groups and the number of nodes in a group are large. We first demonstrate that the CTR exhibits a parametric

sensitivity with respect to the space each group occupies on the unit circle. Then, we offer an explanation for the

observed sensitivity by identifying what is known as a very strong threshold and asymptotic bounds for CTR.

We present a software library that aids in the design of mobile ad hoc networks (MANET). The OMAN design engine

works by taking a specification of network requirements and objectives, and allocates resources which satisfy the input

constraints and maximize the communication performance objective. The tool is used to explore networking design

options and challenges, including: power control, adaptive modulation, flow control, scheduling, mobility, uncertainty in

channel models, and cross-layer design. The unaddressed niche which OMAN seeks to fill is the general framework for

optimization of any network resource, under arbitrary constraints, and with any selection of multiple objectives. While

simulation is an important part of measuring the effectiveness of implemented optimization techniques, the novelty and

focus of OMAN is on proposing novel network design algorithms, aggregating existing approaches, and providing a

general framework for a network designer to test out new proposed resource allocation methods. In this paper, we

present a high-level view of the OMAN architecture, review specific mathematical models used in the network

representation, and show how OMAN is used to evaluate tradeoffs in MANET design. Specifically, we cover three case

studies of optimization. The first case is robust power control under uncertain channel information for a single physical

layer snapshot. The second case is scheduling with the availability of directional radiation patterns. The third case is

optimizing topology through movement planning of relay nodes.

Network Connectivity with a Family of Group Mobility Models

OMAN: A Mobile Ad Hoc Network Design System



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We propose Opportunistic Layered Multicasting (OLM), a joint user scheduling and resource allocation algorithm that

provides enhanced quality and efficiency for layered video multicast over Mobile WiMAX. This work is a lead off and

complete synergy of layered video multicasting with opportunistic concept. The target application is characterized by

groups of users acquiring popular video programs over a fading channel. To accommodate various bandwidth

requirements and device capability, video streams are coded into base and enhancement layers using scalable video

coding technology. Correspondingly, the optimization problems, which select the best subset of users to receive a

specific video layer and assign the most appropriate modulation and coding scheme for this video layer, are specifically

formulated for both video layer types. We also design fast and effective algorithms to bridge the gap between theoretical

throughput capacity and implementation concerns. Thus, the basic video quality can be efficiently guaranteed to all

subscribers while creating most utility out of limited resources on enhancement information. To overcome the inevitable

packet loss in a multicast session, an FEC rate adaptation scheme to approach theoretical performance is also

presented. Favorable performance of the proposed algorithms is demonstrated by simulations utilizing realistic Mobile

WiMAX parameters

In this paper, we present new models and algorithms for control and optimization of a class of next generation

communication networks: hierarchical heterogeneous wireless networks (HHWNs), under real world physical

constraints. Two biology-inspired techniques, a flocking algorithm (FA) and a particle swarm optimizer (PSO), are

investigated in this context. Our model is based on the control framework at the physical layer presented previously by

the authors. We first develop a non-convex mathematical model for HHWNs. Second, we propose a new FA for self-

organization and control of the backbone nodes in an HHWN by collecting local information from end users. Third, we

employ PSO, a widely used artificial intelligence algorithm, to directly optimize the HHWN by collecting global

information from the entire system. A comprehensive evaluation measurement during the optimization process is

developed. In addition, the relationship between HHWN and FA and the comparison of FA and PSO are discussed,

respectively. Our novel framework is examined in various dynamic scenarios. Experimental results demonstrate that FA

and PSO both outperform current algorithms for the self-organization and optimization of HHWN, while showing different

characteristics with respect to convergence speed and quality of solutions.

OLM: Opportunistic Layered Multicasting for Scalable IPTV over Mobile WiMAX

Nature-Inspired Self-Organization, Control, and Optimization in Heterogeneous

Wireless Networks

On the Origins of Heavy-Tailed Delay in Dynamic Spectrum Access Networks



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This paper provides an asymptotic analysis of the transmission delay experienced by SUs for dynamic spectrum access

(DSA) networks. It is shown that DSA induces only light-tailed delay if both the busy time of PU channels and the

message size of SUs are light tailed. On the contrary, if either the busy time or the message size is heavy tailed, then the

SUs' transmission delay is heavy tailed. For this latter case, it is proven that if one of either the busy time or the

message size is light tailed and the other is regularly varying with index α, the transmission delay is regularly varying

with the same index. As a consequence, the delay has an infinite mean provided α <; 1 and an infinite variance provided

α <; 2. Furthermore, if both the busy time and the message size are regularly varying with different indices, then the

delay tail distribution is as heavy as the one with the smaller index. Moreover, the impact of spectrum mobility and

multiradio diversity on the delay performance of SUs is studied. It is shown that both spectrum mobility and multiradio

diversity can greatly mitigate the heavy-tailed delay by increasing the orders of its finite moments.

A major benefit of employing network coding (NC) in cooperative communications (CCs) is its ability to reduce time-slot

overhead. Such approach is called network-coded CC (or NC-CC). Most of the existing works have mainly focused on

exploiting this benefit without considering its potential adverse effect. In this paper, we show that NC may not always

benefit CC. We substantiate this important finding with two important scenarios: employing analog network coding

(ANC) in amplify-and-forward (AF) CC, and digital network coding (DNC) in decode-and-forward (DF) CC. For both

scenarios, we introduce the important concept of network coding noise (NC noise). We analyze the origin of this noise

via a careful study of signal aggregation at a relay node and signal extraction at a destination node. We derive a closed-

form expression for NC noise at each destination node and show that the existence of NC noise could diminish the

advantage of NC in CC. Our results shed new light on how to use NC in CC most effectively.

This paper presents a method of determining the statistical positional accuracy of a moving object being tracked by any

2D (but particularly radiolocation) positioning system without requiring a more accurate reference system. Commonly

for testing performance only static positional errors are measured, but typically for radiolocation systems the positional

performance is significantly different for moving objects compared with stationary objects. When only the overall

statistical performance is required, the paper describes a measurement technique based on determining 1D cross-track

errors from a nominal path, and then using this data set to determine the overall 2D positional error statistics.

Comparison with simulated data shows that the method has good accuracy. The method is also tested with vehicle

tracking in a city and people tracking within a building. For the indoor case, static and dynamic measurements allowed

the degrading effect of body-worn devices due to signal blockage to be determined. Error modeling is also performed

Network Coding in Cooperative Communications: Friend or Foe?

Positional Accuracy Measurement and Error Modeling for Mobile Tracking



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and a Rayleigh-Gamma model is proposed to describe the radial positional errors. It is shown that this model has a good

match with both indoor and outdoor field measurements.

Recently, the IEEE 1900.4 standard specified a policy-based radio resource management (RRM) framework in which the

decision making process is distributed between network-terminal entities. The standard facilitates the optimization of

radio resource usage to improve the overall composite capacity and quality of service (QoS) of heterogeneous wireless

access networks within a composite wireless network (CWN). Hence, the study of different RRM techniques to maintain

either a load- or QoS-balanced system through dynamic load distribution across a CWN is pivotal. In this paper, we

present and evaluate three primary RRM techniques from different aspects, spanning across predictive versus reactive

to model-based versus measurement-based approaches. The first technique is a measurement-based predictive

approach, known as predictive load balancing (PLB), commonly employed in the network-distributed RRM framework.

The second technique is a model-based predictive approach, known as predictive QoS balancing (PQB), typically

implemented in the network-centralized RRM framework. The third technique is a measurement-based reactive

approach, known as reactive QoS balancing (RQB), anchored in the IEEE 1900.4 network-terminal distributed RRM

framework. Comprehensive performance analysis between these three techniques shows that the IEEE 1900.4-based

RQB algorithm yields the best improvement in QoS fairness and aggregate end-user throughput while preserving an

attractive baseline QoS property.

In a tree-based ZigBee network, ZigBee routers (ZRs) must schedule their beacon transmission time to avoid beacon

collisions. The beacon schedule determines packet delivery latency from the end devices to the ZigBee coordinator at

the root of the tree. Traditionally, beacon schedules are chosen such that a ZR does not reuse the beacon slots already

claimed by its neighbors, or the neighbors of its neighbors. We observe, however, that beacon slots can be reused

judiciously, especially when the risk of beacon collision caused by such reuse is low. The advantage of such reuse is

that packet delivery latency can be reduced. We formalize our observation by proposing a node-pair classification

scheme. Based on this scheme, we can easily assess the risk of slot reuse by a node pair. If the risk is high, slot reuse is

disallowed; otherwise, slot reuse is allowed. This forms the essence of our ZigBee-compatible, distributed, risk-aware,

probabilistic beacon scheduling algorithm. Simulation results show that on average the proposed algorithm produces a

latency only 24 percent of that with conventional method, at the cost of 12 percent reduction in the fraction of associated

nodes.

Radio Resource Management of Composite Wireless Networks: Predictive and

Reactive Approaches

Risk-Aware Distributed Beacon Scheduling for Tree-Based ZigBee Wireless Networks

Resource-Optimized Quality-Assured Ambiguous Context Mediation Framework in

Pervasive Environments



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We Pervasive computing applications often involve sensor-rich networking environments that capture various types of

user contexts such as locations, activities, vital signs, and so on. Such context information is useful in a variety of

applications, for example, monitoring health information to promote independent living in "aging-in-place” scenarios, or

providing safety and security of people and infrastructures. In reality, both sensed and interpreted contexts are often

ambiguous, thus leading to potentially dangerous decisions if not properly handled. Therefore, a significant challenge in

the design and development of realistic and deployable context-aware services for pervasive computing applications

lies in the ability to deal with ambiguous contexts. In this paper, we propose a resource-optimized, quality-assured

context mediation framework for sensor networks. The underlying approach is based on efficient context-aware data

fusion, information-theoretic reasoning, and selection of sensor parameters, leading to an optimal state estimation. In

particular, we apply dynamic Bayesian networks to derive context and deal with context ambiguity or error in a

probabilistic manner. Experimental results using SunSPOT sensors demonstrate the promise of this approach.

We consider the problem of relay-assisted transmission for cellular networks. In the considered system, a source node

together with n relay nodes are selected in a proportionally fair (PF) manner to transmit to the base station (BS), which

uses the maximal ratio combining (MRC) to combine the signals received from the source node in the first half slot and

the n relay nodes in the second half slot for successful reception. The proposed algorithm incorporates the PF criterion

and cooperative diversity, and is called proportionally fair cooperation (PFC). Compared with the proportional fair

scheduling (PFS) algorithm, PFC provides improved efficiency and fairness. The ordinary differential equation (ODE)

analysis used to study PFS cannot be used for PFC; otherwise, one has to solve a large number of nonlinear and

interrelated ODE equations which is time prohibited. In this paper, we present a mathematical framework for the

performance of PFC. The cornerstone of our framework is a realistic yet simple model that captures node cooperation,

fading, and fair resource allocation-induced dependencies. We obtain analytical expressions for the throughput gain of

PFC over traditional PFS without node cooperation. Compared with the highly time-consuming ordinary differential

equation analysis, our formulae are intuitive yet easy to evaluate numerically. To our knowledge, it is the first time that a

closed-form expression is obtained for the throughput of relay-assisted transmission in a cellular network with the PF

constraint.

Relay-Assisted Transmission with Fairness Constraint for Cellular Networks

RAM: Rate Adaptation in Mobile Environments



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Channel asymmetry and high fluctuation of channel conditions are two salient characteristics of wireless channels in

mobile environments. Therefore, when using IEEE 802.11 devices in mobile environments, it is critical to have an

effective rate adaptation scheme that can deal with these issues. In this paper, we propose a practical rate adaptation

scheme called Rate Adaptation in Mobile environments (RAM) and implement it in the MadWifi device driver. RAM uses a

receiver-based approach to handle channel asymmetry and a conservative SNR prediction algorithm to deal with high

channel fluctuation. More importantly, RAM allows the receiver to convey the feedback information to the transmitter in

a creative manner via ACK transmission rate variation, which does not require changes to the device firmware and

hence is implementable at the device driver level. In addition, RAM adopts an effective scheme to guarantee that RAM-

based and legacy IEEE 802.11 devices can interoperate with each other. The effectiveness of RAM is demonstrated via

in-depth experimental evaluation in indoor static and mobile environments as well as outdoor vehicular environments.

We Cognitive Radio (CR) technology is a promising solution to enhance the spectrum utilization by enabling unlicensed

users to exploit the spectrum in an opportunistic manner. Since unlicensed users are temporary visitors to the licensed

spectrum, they are required to vacate the spectrum when a licensed user reclaims it. Due to the randomness of the

appearance of licensed users, disruptions to both licensed and unlicensed communications are often difficult to

prevent, which may lead to low throughput of both licensed and unlicensed communications. In this paper, a proactive

spectrum handoff framework for CR ad hoc networks, ProSpect, is proposed to address these concerns. In the proposed

framework, Channel-Switching (CW) policies and a proactive spectrum handoff protocol are proposed to let unlicensed

users vacate a channel before a licensed user utilizes it to avoid unwanted interference. Network coordination schemes

for unlicensed users are also incorporated into the spectrum handoff protocol design. Moreover, a distributed channel

selection scheme to eliminate collisions among unlicensed users in a multiuser spectrum handoff scenario is proposed.

In our proposed framework, unlicensed users coordinate with each other without using a Common Control Channel

(CCC), which is highly adaptable in a spectrum-varying environment. We compare our proposed proactive spectrum

handoff protocol with a reactive spectrum handoff protocol, under which unlicensed users switch channels after

collisions with licensed transmissions occur. Simulation results show that our proactive spectrum handoff outperforms

the reactive spectrum handoff approach in terms of higher throughput and fewer collisions to licensed users.

Furthermore, our distributed channel selection can achieve higher packet delivery rate in a multiuser spectrum handoff

scenario, compared with existing channel selection schemes

While many protocols for sensor network security provide confidentiality for the content of messages, contextual

information usually remains exposed. Such contextual information can be exploited by an adversary to derive sensitive

information such as the locations of monitored objects and data sinks in the field. Attacks on these components can

ProSpect: A Proactive Spectrum Handoff Framework for Cognitive Radio Ad Hoc

Networks without Common Control Channel

Protecting Location Privacy in Sensor Networks against a Global Eavesdropper



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significantly undermine any network application. Existing techniques defend the leakage of location information from a

limited adversary who can only observe network traffic in a small region. However, a stronger adversary, the global

eavesdropper, is realistic and can defeat these existing techniques. This paper first formalizes the location privacy

issues in sensor networks under this strong adversary model and computes a lower bound on the communication

overhead needed for achieving a given level of location privacy. The paper then proposes two techniques to provide

location privacy to monitored objects (source-location privacy)-periodic collection and source simulation-and two

techniques to provide location privacy to data sinks (sink-location privacy)-sink simulation and backbone flooding.

These techniques provide trade-offs between privacy, communication cost, and latency. Through analysis and

simulation, we demonstrate that the proposed techniques are efficient and effective for source and sink-location privacy

in sensor networks.

This paper presents a novel approach to building a WLAN-based location fingerprinting system. Our algorithm

intelligently transforms received signal strength (RSS) into principal components (PCs) such that the information of all

access points (APs) is more efficiently utilized. Instead of selecting APs, the proposed technique replaces the elements

with a subset of PCs to simultaneously improve the accuracy and reduce the online computation. Our experiments are

conducted in a realistic WLAN environment. The results show that the mean error is reduced by 33.75 percent, and the

complexity by 40 percent, as compared to the existing methods. Moreover, several benefits of our algorithm are

demonstrated, such as requiring fewer training samples and enhancing the robustness to RSS anomalies.

We implement a new software-based multihop TDMA MAC protocol (Soft-TDMAC) with microsecond synchronization

using a novel system interface for development of 802.11 overlay TDMA MAC protocols (SySI-MAC). SySI-MAC provides

a kernel independent message-based interface for scheduling transmissions and sending and receiving 802.11 packets.

The key feature of SySI-MAC is that it provides near deterministic timers and transmission times, which allows for

implementation of highly synchronized TDMA MAC protocols. Building on SySI-MAC's predictable transmission times,

we implement Soft-TDMAC, a software-based 802.11 overlay multihop TDMA MAC protocol. Soft-TDMAC has a

synchronization mechanism, which synchronizes all pairs of network clocks to within microseconds of each other.

Building on pairwise synchronization, Soft-TDMAC achieves tight network-wide synchronization. With network-wide

synchronization independent of data transmissions, Soft-TDMAC can schedule arbitrary TDMA transmission patterns.

Principal Component Localization in Indoor WLAN Environments

Soft-TDMAC: A Software-Based802.11 Overlay TDMA MAC with Microsecond

Synchronization



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For example, Soft-TDMAC allows schedules that decrease end-to-end delay and take end-to-end rate demands into

account. We summarize hundreds of hours of testing Soft-TDMAC on a multihop testbed, showing the synchronization

capabilities of the protocol and the benefits of flexible scheduling.

In this paper, the relative location estimation problem, a prominent issue faced by several applications in wireless

sensor networks (WSNs), is considered. Sensors are classified into two categories: location-aware and location-unaware

sensors. To estimate the positions of location-unaware sensors, exact positions are often assumed for location-aware

sensors. However, in practice, such precise data may not be available. Therefore, determining the positions of location-

unaware sensors in the presence of inexact positions of location-aware sensors is the primary focus of this study. A

robust min-max optimization method is proposed for the relative location estimation problem by minimizing the worst-

case estimation error. The corresponding optimization problem is originally nonconvex, but after it is transformed into a

convex semidefinite program (SDP), it can be solved by existing numerical techniques. In the presence of inexact

positions of location-aware sensors, the robustness of the proposed approach is validated by simulations under

different WSN topologies. Modified maximum-likelihood (ML) estimation and second-order cone programming (SOCP)

relaxation methods have been used for localization in comparison with the proposed approach.

Throughput capacity in mobile ad hoc networks has been studied extensively under many different mobility models.

However, most previous research assumes global mobility, and the results show that a constant per-node throughput

can be achieved at the cost of very high delay. Thus, we are having a very big gap here, i.e., either low throughput and

low delay in static networks or high throughput and high delay in mobile networks. In this paper, employing a practical

restricted random mobility model, we try to fill this gap. Specifically, we assume that a network of unit area with n nodes

is evenly divided into cells with an area of n -2α, each of which is further evenly divided into squares with an area of n-

2β(0≤ α ≤ β ≤1/2). All nodes can only move inside the cell which they are initially distributed in, and at the beginning of

each time slot, every node moves from its current square to a uniformly chosen point in a uniformly chosen adjacent

square. By proposing a new multihop relay scheme, we present smooth trade-offs between throughput and delay by

controlling nodes' mobility. We also consider a network of area nγ (0 ≤ γ ≤ 1) and find that network size does not affect

the results obtained before.

Robust Relative Location Estimation in Wireless Sensor Networks with Inexact

Position Problems

Smooth Trade-Offs between Throughput and Delay in Mobile Ad Hoc Networks

Scalable Activity-Travel Pattern Monitoring Framework for Large-Scale City

Environment



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In this paper, we introduce Activity Travel Pattern (ATP) monitoring in a large-scale city environment. ATP represents

where city residents and vehicles stay and how they travel around in a complex megacity. Monitoring ATP will incubate

new types of value-added services such as predictive mobile advertisement, demand forecasting for urban stores, and

adaptive transportation scheduling. To enable ATP monitoring, we develop ActraMon, a high-performanceATP

monitoring framework. As a first step, ActraMon provides a simple but effective computational model of ATP and a

declarative query language facilitating effective specification of various ATP monitoring queries. More important,

ActraMon employs the shared staging architecture and highly efficient processing techniques, which address the

scalability challenges caused by massive location updates, a number of ATP monitoring queries and processing

complexity of ATP monitoring. Finally, we demonstrate the extensive performance study of ActraMon using realistic city-

wide ATP workloads.

A fundamental question in multihop wireless network protocol design is how to partition the network's transport

capacity among contending flows. A classically "fair” allocation leads to poor throughput performance for all flows

because connections that traverse a large number of hops (i.e., long connections) consume a disproportionate share of

resources. However, naively biasing against longer connections can lead to poor network utilization, because a

significantly high fraction of total connections are long in large networks with spatially uniform traffic. While

proportional fair allocation provides a significant improvement, we show here that there is a much richer space of

resource allocation strategies for introducing a controlled bias against resource-intensive long connections in order to

significantly improve the performance of shorter connections. Specifically, mixing strongly biased allocations with fairer

allocations leads to efficient network utilization as well as a superior trade-off between flow throughput and fairness. We

present an analytical model that offers insight into the impact of a particular resource allocation strategy on network

performance, taking into account finite network size and spatial traffic patterns. We point to protocol design options to

implement our resource allocation strategies by invoking the connection with the well-studied network utility

maximization framework. Our simulation evaluation serves to verify the analytical design prescriptions.

A fundamental question in multihop wireless network protocol design is how to partition the network's transport

capacity among contending flows. A classically "fair” allocation leads to poor throughput performance for all flows

Shaping Throughput Profiles in Multihop Wireless Networks:A Resource-Biasing

Approach

Secure Initialization of Multiple Constrained Wireless Devices for an Unaided User



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because connections that traverse a large number of hops (i.e., long connections) consume a disproportionate share of

resources. However, naively biasing against longer connections can lead to poor network utilization, because a

significantly high fraction of total connections are long in large networks with spatially uniform traffic. While

proportional fair allocation provides a significant improvement, we show here that there is a much richer space of

resource allocation strategies for introducing a controlled bias against resource-intensive long connections in order to

significantly improve the performance of shorter connections. Specifically, mixing strongly biased allocations with fairer

allocations leads to efficient network utilization as well as a superior trade-off between flow throughput and fairness. We

present an analytical model that offers insight into the impact of a particular resource allocation strategy on network

performance, taking into account finite network size and spatial traffic patterns. We point to protocol design options to

implement our resource allocation strategies by invoking the connection with the well-studied network utility

maximization framework. Our simulation evaluation serves to verify the analytical design prescriptions.

Cognitive radio (CR) networks have been proposed as a solution to both spectrum inefficiency and spectrum scarcity

problems. However, they face several challenges based on the fluctuating nature of the available spectrum, making it

more difficult to support seamless communications, especially in CR cellular networks. In this paper, a spectrum-aware

mobility management scheme is proposed for CR cellular networks. First, a novel network architecture is introduced to

mitigate heterogeneous spectrum availability. Based on this architecture, a unified mobility management framework is

developed to support diverse mobility events in CR networks, which consists of spectrum mobility management, user

mobility management, and intercell resource allocation. The spectrum mobility management scheme determines a target

cell and spectrum band for CR users adaptively dependent on time-varying spectrum opportunities, leading to increase

in cell capacity. In the user mobility management scheme, a mobile user selects a proper handoff mechanism so as to

minimize a switching latency at the cell boundary by considering spatially heterogeneous spectrum availability. Intercell

resource allocation helps to improve the performance of both mobility management schemes by efficiently sharing

spectrum resources with multiple cells. Simulation results show that the proposed method can achieve better

performance than conventional handoff schemes in terms of both cell capacity as well as mobility support in

communications.

The 2010 FCC ruling on white spaces proposes relying on a database of incumbents as the primary means of

determining white space availability at any white space device (WSD). While the ruling provides broad guidelines for the

database, the specifics of its design, features, implementation, and use are yet to be determined. Furthermore,

Spectrum-Aware Mobility Management in Cognitive Radio Cellular Networks

SenseLess: A Database-Driven White Spaces Network



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architecting a network where all WSDs rely on the database raises several systems and networking challenges that have

remained unexplored. Also, the ruling treats the database only as a storehouse for incumbents. We believe that the

mandated use of the database has an additional opportunity: a means to dynamically manage the RF spectrum.

Motivated by this opportunity, in this paper, we present SenseLess, a database-driven white spaces network. As

suggested by its very name, in SenseLess, WSDs rely on a database service to determine white spaces availability as

opposed to spectrum sensing. The service, using a combination of an up-to-date database of incumbents, sophisticated

signal propagation modeling, and an efficient content dissemination mechanism to ensure efficient, scalable, and safe

white space network operation. We build, deploy, and evaluate SenseLess and compare our results to ground truth

spectrum measurements. We present the unique system design considerations that arise due to operating over the

white spaces. We also evaluate its efficiency and scalability. To the best of our knowledge, this is the first paper that

identifies and examines the systems and networking challenges that arise from operating a white space network, which

is solely dependent on a channel occupancy database.

Multicast routing protocols typically rely on the a priori creation of a multicast tree (or mesh), which requires the

individual nodes to maintain state information. In dynamic networks with bursty traffic, where long periods of silence are

expected between the bursts of data, this multicast state maintenance adds a large amount of communication,

processing, and memory overhead for no benefit to the application. Thus, we have developed a stateless receiver-based

multicast (RBMulticast) protocol that simply uses a list of the multicast members' (e.g., sinks') addresses, embedded in

packet headers, to enable receivers to decide the best way to forward the multicast traffic. This protocol, called

Receiver-Based Multicast, exploits the knowledge of the geographic locations of the nodes to remove the need for costly

state maintenance (e.g., tree/mesh/neighbor table maintenance), making it ideally suited for multicasting in dynamic

networks. RBMulticast was implemented in the OPNET simulator and tested using a sensor network implementation.

Both simulation and experimental results confirm that RBMulticast provides high success rates and low delay without

the burden of state maintenance.

We proposed an analytical model to study the interplay between medium access control (MAC) and packet forwarding

disciplines in multihop wireless networks. The model jointly considers the channel access procedure and the active

portions of the topology, which is determined by packet forwarding discipline. The model allows the computation of per-

node performance metrics for any given network topology and the combination of specific MAC protocols and packet

forwarding methods. As an example of the applicability of our modeling framework, the analytical model is used to study

Stateless Multicast Protocol for Ad Hoc Networks

Understanding the Interaction between Packet Forwarding and Channel Access in

Multihop Wireless Networks



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the performance of multihop wireless networks using a contention-based MAC protocol (the IEEE 802.11 distributed

coordination function) and a schedule-based MAC protocol (NAMA), together with different packet forwarding schemes

in multihop networks. The analytical results derived from the model are validated with discrete-event simulations in

Qualnet; the analytical results are shown to be very close to those attained by simulations.

We consider variations of a problem in which data must be delivered to mobile clients en-route, as they travel towards

their destinations. The data can only be delivered to the mobile clients as they pass within range of wireless base

stations. Example scenarios include the delivery of building maps to firefighters responding to multiple alarms, and the

in-transit ldquoilluminationrdquo of simultaneous surface-to-air missiles. We cast this scenario as a parallel-machine

scheduling problem with the little-studied property that jobs may have different release times and deadlines when

assigned to different machines. We present new algorithms and also adapt existing algorithms, for both online and

offline settings. We evaluate these algorithms on a variety of problem instance types, using both synthetic and real-

world data, including several geographical scenarios, and show that our algorithms produce schedules achieving near-

optimal throughput.

In this paper, we study the availability of TV white spaces in Europe. Specifically, we focus on the 470-790 MHz UHF

band, which will predominantly remain in use for TV broadcasting after the analog-to-digital switch-over and the

assignment of the 800 MHz band to licensed services have been completed. The expected number of unused, available

TV channels in any location of the 11 countries we studied is 56 percent when we adopt the statistical channel model of

the ITU-R. Similarly, a person residing in these countries can expect to enjoy 49 percent unused TV channels. If, in

addition, restrictions apply to the use of adjacent TV channels, these numbers reduce to 25 and 18 percent, respectively.

These figures are significantly smaller than those recently reported for the United States. We also study how these

results change when we use the Longley-Rice irregular terrain model instead. We show that while the overall expected

availability of white spaces is essentially the same, the local variability of the available spectrum shows significant

changes. This underlines the importance of using appropriate system models before making far-reaching conclusions.

Who, When, Where: Timeslot Assignment to Mobile Clients

TV White Space in Europe

Target Tracking in Wireless Sensor Networks Based on the Combination of KF and

MLE Using Distance Measurements



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In A common technical difficulty in target tracking in a wireless sensor network is that individual homogeneous sensors

only measure their distances to the target whereas the state of the target composes of its position and velocity in the

Cartesian coordinates. That is, the senor measurements are nonlinear in the target state. Extended Kalman filtering is a

commonly used method to deal with the nonlinearity, but this often leads to unsatisfactory or even unstable tracking

performances. In this paper, we present a new target tracking approach which avoids the instability problem and offers

superior tracking performances. We first propose an improved noise model which incorporates both additive noises and

multiplicative noises in distance sensing. We then use a maximum likelihood estimator for prelocalization to remove the

sensing nonlinearity before applying a standard Kalman filter. The advantages of the proposed approach are

demonstrated via experimental and simulation results.

This paper addresses the problem of delivering data packets for highly dynamic mobile ad hoc networks in a reliable

and timely manner. Most existing ad hoc routing protocols are susceptible to node mobility, especially for large-scale

networks. Driven by this issue, we propose an efficient Position-based Opportunistic Routing (POR) protocol which

takes advantage of the stateless property of geographic routing and the broadcast nature of wireless medium. When a

data packet is sent out, some of the neighbor nodes that have overheard the transmission will serve as forwarding

candidates, and take turn to forward the packet if it is not relayed by the specific best forwarder within a certain period

of time. By utilizing such in-the-air backup, communication is maintained without being interrupted. The additional

latency incurred by local route recovery is greatly reduced and the duplicate relaying caused by packet reroute is also

decreased. In the case of communication hole, a Virtual Destination-based Void Handling (VDVH) scheme is further

proposed to work together with POR. Both theoretical analysis and simulation results show that POR achieves excellent

performance even under high node mobility with acceptable overhead and the new void handling scheme also works

well.

The Marauder's Map,” a magical map in J.K. Rowling's fantasy series Harry Potter and the Prisoner of Azkaban [CHECK

END OF SENTENCE], can be used as a surveillance tool to show all moving objects within the boundary of "Hogwarts

School of Witchcraft and Wizardry” at a spell. In this paper, we introduce a similar forensic surveillance tool for wireless

networks. Our system, the digital Marauder's map, can reveal the locations of WiFi-enabled mobile devices within the

coverage area of a high-gain antenna. The digital Marauder's map is built solely with off-the-shelf wireless equipments,

and features a mobile design that can be quickly deployed to a new location for instant usage without training. We

Toward Reliable Data Delivery for Highly Dynamic Mobile Ad Hoc Networks

The Digital Marauder's Map: A WiFi Forensic Positioning Tool



EGC

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present a comprehensive set of theoretical analysis and experimental results which demonstrate the coverage and

localization accuracy of the digital Marauder's map.

We present the boomerang protocol to efficiently retain information at a particular geographic location in a sparse

network of highly mobile nodes without using infrastructure networks. To retain information around certain physical

location, each mobile device passing that location will carry the information for a short while. This approach can become

challenging for remote locations around which only few nodes pass by. To address this challenge, the boomerang

protocol, similar to delay-tolerant communication, first allows a mobile node to carry packets away from their location of

origin and periodically returns them to the anchor location. A unique feature of this protocol is that it records the

geographical trajectory while moving away from the origin and exploits the recorded trajectory to optimize the return

path. Simulations using automotive traffic traces for a southern New Jersey region show that the boomerang protocol

improves packet return rate by 70 percent compared to a baseline shortest path routing protocol. This performance gain

can become even more significant when the road map is less connected. Finally, we look at adaptive protocols that can

return information within specified time limits.

The Boomerang Protocol: Tying Data to Geographic Locations in Mobile Disconnected

Networks

ieee projects 2012 2013 - mobile computing

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