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Channel Assignment and Load Distribution in a Power-Managed WLAN
This paper discusses a proposed algorithm. Abstract: For a Wireless Local Area Network (WLAN), the authors propose an algorithm based on power management of Access Points (APs) to improve load distribution and provide an improved channel assignment. The authors formulate an algorithm that adjusts the transmitted power of the beacon packets of the Most Congested Access Point (MCAP). The transmitted power of the data packets is not altered thus avoiding auto-rating. The algorithm then determines a user assignment that distributes the load efficiently. Finally, the authors apply a channel assignment algorithm to each AP with the objective of minimizing the total interference over the WLAN. Results show that the proposed algorithm is capable of significantly reducing the congestion at the MCAPs, providing better load distribution, and enhancing channel assignment. digital.library.unt.edu/ark:/67531/metadc30835/
Channel Assignment in an IEEE 802.11 WLAN Based on Signal-to-Interference Ratio
Abstract: In this paper, we propose a channel-assignment algorithm at the Access Points (APs) of a Wireless Local Area Network (WLAN) in order to maximize Signal-to-Interference Ratio (SIR) at the user level. It begins with the channel assignment at the APs, which is based on minimizing the total interference between APs. Based on this initial assignment, the authors calculate the SIR for each user. The algorithm can be applied to any WLAN, irrespective of the user distribution and user load. Results show that the proposed algorithm is capable of significantly increasing the SIR over the WLAN, which in turn improves throughput. digital.library.unt.edu/ark:/67531/metadc30844/
Performance Enhancement by Eliminating Redundant Function Execution
This paper discusses performance enhancement by eliminating redundant function execution. Programs often call the same function with the same arguments, yielding the same results. The authors call this phenomenon, "function reuse". Previously, we have shown such a behavior for some of the SPEC2000 integer benchmarks using HP ATOM instrumentation tools. However, this required extensive analysis by hand, and assumptions regarding side-effects caused by functions. In this paper, the authors modified a well-known architecture simulator, SimpleScalar, to analyze multiple benchmarks to investigate the function reuse behavior. digital.library.unt.edu/ark:/67531/metadc30830/
Classification of Attributes and Behavior in Risk Management Using Bayesian Networks
This paper discusses issues in security. Abstract: Security administration is an uphill task to implement in an enterprise network providing secured corporate services. With the slew of patches being released by network component vendors, system administrators require a barrage of tools for analyzing the risk due to vulnerabilities in those components. In addition, criticalities in patching some end hosts raises serious security issues about the network to which the end hosts are connected. In this context, it would be imperative to know the risk level of all critical resources keeping in view the everyday emerging new vulnerabilities. The authors hypothesize that sequence of network actions by attackers depends on their social and attack profile (behavioral resources such as skill level, time, and attitude). To estimate the types of attack behavior, the athors surveyed individuals for their ability and attack intent. Using the individuals' responses, the authors determined their behavioral resources and classified them as having opportunist, hacker, or explorer behavior. The profile behavioral resources can be used for determining risk by an attacker having that profile. Thus, suitable vulnerability analysis and risk management strategies can be formulated to efficiently curtail the risk from different types of attackers. digital.library.unt.edu/ark:/67531/metadc30836/
Attracting and Retaining Women in Computer Science and Engineering: Evaluating the Results
This paper discusses efforts to attract and retain students in computer science and engineering fields. Abstract: Computer science and engineering communities have been exploring a variety of activities and techniques to attract and retain more students, especially women and minorities, to computer science and computer engineering degree programs. This paper briefly describes the efforts and results of a plan for actively recruiting young women into undergraduate computer engineering and computer science programs hosted by the University of North Texas (UNT). It also describes a series of activities aimed at improving the retention rate of students already in our programs, particularly during the freshman year. Such recruitment and retention efforts are critical to the country's efforts to increase the number of engineering professionals, and are a priority for the Computer Science and Engineering (CSE) Department at UNT. digital.library.unt.edu/ark:/67531/metadc30834/
Capacity Allocations in Multi-cell UMTS Networks for Different Spreading Factors with Perfect and Imperfect Power Control
This paper discusses capacity allocation in multi-cell UMTS networks. Abstract: An analytical model for calculating capacity in multi-cell UMTS networks is presented. Capacity is maximized for different spreading factors and for perfect and imperfect power control. An analytical model is presented for approximating the user distributions in multi-cell third generation WCDMA networks using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distribution for every cell. This allows for the calculation of the inter-cell interference and the reverse-link capacity of the network. The capacity was determined for signal-to-interference threshold from 5 dB to 10 dB and spreading factor values of 256, 64, 16, and 4. digital.library.unt.edu/ark:/67531/metadc30825/
Approximating User Distributions in WCDMA Networks Using 2-D Gaussian
This paper discusses approximating user distributions in WCDMA networks using 2-D Gaussian. Abstract: In this paper, we present an analytical model for approximating the user distributions in multi-cell third generation WCDMA networks using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This allows us to calculate the inter-cell interference and the reverse-link capacity of the network. The authors compare their model with simulation results and show that it is fast and accurate enough to be used efficiently in the planning process of large WCDMA networks. digital.library.unt.edu/ark:/67531/metadc30820/
Mobility-Based CAC Algorithm for Arbitrary Call-Arrival Rates in CDMA Cellular Systems
This paper presents a novel approach for designing a call-admission control (CAC) algorithm for code-division multiple-access (CDMA) networks with arbitrary call-arrival rates. The design of the CAC algorithm uses global information; it incorporates the call-arrival rates and the user mobilities across the network and guarantees the users' quality of service (QoS) as well as prescribed blocking probabilities. On the other hand, its implementation in each cell uses local information; it only requires the number of calls currently active in that cell. The authors present several cases for a nontrivial network topology where their CAC algorithm guarantees QoS and blocking probabilities while achieving significantly higher throughput than that achieved by traditional techniques. The authors also calculate the network capacity, i.e., the maximum throughput for the entire network, for prespecified blocking probabilities and QoS requirements. digital.library.unt.edu/ark:/67531/metadc30821/
Dynamic Channel Assignment in IEEE 802.11 Networks
This paper discusses dynamic channel assignment in IEEE 802.11 networks. Abstract: We design a dynamic channel assignment algorithm for IEEE 802.11 wireless networks. Our algorithm assigns channels dynamically in a way that minimizes channel interference generated by neighboring access points (APs) on a reference access point, resulting in higher throughput. We implement and simulate their algorithm using two versions (1: pick randomly 2: pick first) and different number of APs (4, 9, 16, and 25). Analysis of this algorithm shows an improvement by a factor of 4 (by lowering the total interference on an AP by 6 dBm on average) over default settings of having all APs use the same channel. As the number of APs is increased in a given service area, dynamic channel assignment becomes crucial; otherwise overlapping channel interference becomes a limiting factor. digital.library.unt.edu/ark:/67531/metadc30837/
UMTS Capacity and Throughput Maximization for Different Spreading Factors
This article discusses UMTS capacity and throughput maximization for different spreading factors. An analytical model for calculating capacity in multi-cell UMTS networks is presented. Capacity is maximized for different spreading factors and for perfect and imperfect power control. The authors also design and implement a local call admission control (CAC) algorithm which allows for the simulation of network throughput for different spreading factors and various mobility scenarios. The design of the CAC algorithm uses global information ; it incorporates the call arrival rates and the user mobilities across the network and guarantees the users' quality of service as well as pre-specified blocking probabilities. On the other hand, its implementation in each cell uses local information; it only requires the number of calls currently active in that cell. The capacity and network throughput were determined for signal-to-interference threshold from 5 dB to 10 dB and spreading factor values of 256, 64, 16, and 4. digital.library.unt.edu/ark:/67531/metadc30833/
User-Based Channel Assignment Algorithm in a Load-Balanced IEEE 802.11 WLAN
This article discusses a user-based channel assignment algorithm in a load-balanced IEEE 802.11 WLAN. A new load balancing algorithm is presented based on power management of Access Points (APs) to reduce congestion at hot spots in Wireless Local Area Networks (WLANs) and to assign channels to APs. The algorithm first finds the Most Congested Access Point (MCAP), then decreases its transmitted power in discrete steps, and the process continues until the users' assignment which leads to a high balance index is reached. A new mathematical programming formulation is then applied to assign channels to the APs such that the Signal-to-Interference Ratio (SIR) at the users' level is maximized. Results show that the algorithm is capable of reducing the overall congestion at hot spots in a WLAN and increases the SIR significantly for cases involving relatively large WLANs. In the process, network throughput is increased. digital.library.unt.edu/ark:/67531/metadc30851/
Non-Uniform Grid-Based Routing in Sensor Networks
This paper discusses non-uniform grid-based routing in sensor networks. A non-uniform grid-based coordinated routing design in wireless sensor networks is presented. The conditions leading to network partition and analysis of energy consumption that prolongs the network lifetime are studied. The authors implement routing in heavily populated sensor networks. By maintaining constant values for parameters such as path loss exponent, receiver sensitivity and transmit power, and varying between uniform and non-uniform grids, we observe energy consumption patters for each of the grid structures, and infer from the network lifetime the better suited grids for uniformly and randomly deployed sensor nodes. digital.library.unt.edu/ark:/67531/metadc30847/
Optimal Load Distribution in Large Scale WLAN Networks Utilizing a Power Management Algorithm
This paper presents an algorithm, based on power management of Access Points (AP), to reduce congestion in Wireless Local Area Networks (WLANs). The algorithm finds the Most Congested Access Point (MCAP) and adjusts its transmitted power in discrete steps and determines the optimal users' assignment such that an optimal load distribution is achieved. Results show that the algorithm is capable of significantly reducing the overall congestion in the WLAN. digital.library.unt.edu/ark:/67531/metadc30843/
Optimal Access Point Selection and Traffic Allocation in IEEE 802.11 Networks
This paper discusses optimal access point selection and the traffic allocation in IEEE 802.11 networks. The authors design an optimal access point (AP) selection and traffic allocation algorithm for IEEE 802.11 networks. Coverage and capacity are some key issues when selecting APs in a demand area. APs need to cover all users, i.e., a user is considered covered if the power received from its corresponding AP is greater than a given threshold. Moreover, from a capacity standpoint, APs need to provide certain bandwidth to users located in the coverage area. Our optimization balances the load on the entire network whereby demand clusters will not necessarily select the closest AP that has the largest signal level but one that can still service the demand cluster and provide ample bandwidth. digital.library.unt.edu/ark:/67531/metadc30822/
Parity Assisted Decision Making for QAM Modulation
This paper discusses parity assisted decision making for QAM modulation. A simple technique which involves the transmission of a Quadrature Amplitude Modulation (QAM) symbol and two parity bits in separate channels to improve the performance of communication systems is devised. When a symbol is received, a decision is made not solely by its Euclidean distances to the constellation points. Rather, the two parity bits are used to assist in making the decision. Unlike standard error correcting codes (ECC), the proposed method operates on the received symbols at the detector level and before the ECC. The parity bits and the information symbols can be sent in different channels (frequency division) or at different times on the same channel (time division). The available energy for transmission can be distributed unevenly among the information bits and the parity bits to improve the performance. Simulation results show large gains in required signal to noise ratios over uncoded system to achieve the same performance. The scheme is simple and is well suited for systems with low computational power. digital.library.unt.edu/ark:/67531/metadc30829/
The Effect of an Enhanced Channel Assignment Algorithm on an IEEE 802.11 WLAN
This article discusses the effect of an enhanced channel assignment algorithm on an IEEE 802.11 WLAN. Abstract: In this paper, a channel-assignment algorithm at the Access Points (APs) of a Wireless Local Area Network (WLAN) is proposed in order to maximize Signal-to-Interference Ratio (SIR) at the user level. We start with an initial channel assignment based on minimizing the total interference between APs. Based on this assignment, we calculate the SIR for each user. Then, another channel assignment is performed based on maximizing the SIR at the users. The algorithm can be applied to any WLAN, irrespective of the users' and load distributions. Simulation results showed that the proposed algorithm is capable of significantly increasing the SIR over the WLAN, which in turn improves throughput. Finally, several scenarios were constructed using OPNET simulation tool to validate our results. digital.library.unt.edu/ark:/67531/metadc30846/
Effects of Interference on Capacity in Multi-Cell CDMA Networks
This article discusses the effects of interference on capacity in multi-cell CDMA networks. Abstract: An overwhelming number of models in the literature use average interference for calculation of capacity of a CDMA network. In this paper, we calculate the actual per-user interference and analyze the effect of user-distribution on the capacity of a CDMA network. We show that even though the capacity obtained using average interference is a good approximation to the capacity calculated using actual interference for a uniform user distributions, the deviation can be tremendously large for non-uniform user distributions. We also present an analytical model for approximating the user distributions using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This allows us to calculate the inter-cell interference and the reverse-link capacity of the network. We compare their model with simulation results and show that it is fast and accurate enough to be used efficiently in the planning process of large CDMA networks. digital.library.unt.edu/ark:/67531/metadc30826/
An Efficient Non-Preemptive Real-Time Scheduling
This paper discusses non-preemptive, real-time scheduling. Abstract: Traditional real-time systems are designed using preemptive scheduling and worst-case execution time estimates to guarantee the execution of high priority tasks. There is, however, an interest in exploring non-preemptive scheduling models for real-time systems, particularly for soft real-time multimedia applications. In this paper, we propose a new algorithm that uses multiple scheduling strategies. The goal of this research is to improve the success rate of the well-known Earliest Deadline First (EDF) approach even when the load on the system is very high. The approach, known as group-EDF (gEDF) is based on (dynamic) grouping of tasks with deadlines that are very close to each other, and using Shortest Job First (SJF) technique to schedule tasks within the group. We present results comparing gEDF and EDF using randomly generated tasks with varying execution times, release times, deadlines and tolerance to missing deadlines, under varying workloads. We believe that the grouping of tasks with similar deadlines and utilizing information other than deadlines (such as execution times, priorities or resource availability) for scheduling tasks within a group can lead to new and more efficient real-time scheduling algorithms. digital.library.unt.edu/ark:/67531/metadc30819/
Throughput Validation of an Advanced Channel Assignment Algorithm in IEEE 802.11 WLAN
In this article, an enhanced channel-assignment algorithm at the Access Points (APs) of a Wireless Local Area Network (WLAN) is validated. The algorithm aims to maximize the Signal-to-Interference Ratio (SIR) at the user level in order to determine the appropriate channel at the APs. The initial channel assignment step at the APs is based on minimizing the total interference between APs. Based on this initial assignment, the SIR for each user is calculated. Then, another channel assignment is performed based on maximizing the SIR at the users. The algorithm can be applied to any WLAN, irrespective of the user distribution and user load. Results show that the algorithm is capable of significantly increasing the SIR over the WLAN, which in turn should improve throughput. Therefore, the authors use OPNET simulation tool to construct several realistic scenarios in order to validate our results. digital.library.unt.edu/ark:/67531/metadc30850/
Throughput Optimization in Multi-Cell CDMA Networks
In this paper, the authors investigate the performance of a multi-cell CDMA network by determining the maximum throughput that the network can archive for a given grade-of-service requirement, quality-of-service requirement, network topology and call arrival rate profile. The analysis is restricted to the reverse link and accounts for mobility of users between cell. A constrained nonlinear optimization problem is formulated that maximizes the network throughput subject to upper bounds on the blocking probabilities and a lower bound on the bit energy to interference ratio. The goal is to optimize the usage of network resources, provide consistent grade-of-service for all the cells in the network, and maintain a pre-specified quality-of-service. The solution to the optimization problem yields the maximum network throughput as well as the maximum number of calls that should be admitted in each cell for a given topology and call arrival rate profile. Our optimization algorithm yields significantly higher throughput compared with traditional call admission schemes. digital.library.unt.edu/ark:/67531/metadc30823/
Retention and Recruitment of Women in Computer Engineering
This paper describes the efforts and results of a plan for actively recruiting women students to undergraduate computer engineering programs at the University of North Texas (UNT). It also describes a series of activities aimed at improving retention rates of women students already in our programs. Such recruitment and retention of women is critical to the country's efforts to increase the number of engineering professionals, and is a priority for the Computer Science and Engineering (CSE) Department at UNT. digital.library.unt.edu/ark:/67531/metadc30831/
Robocamp: Encouraging Young Women to Embrace STEM
This paper describes the efforts and results of a plan for actively recruiting students to undergraduate computer science and engineering programs at the University of North Texas (UNT). Such recruitment of students is critical to the country's efforts to increase the number of engineering professionals, and is a priority for the Computer Science and Engineering (CSE) Department at UNT. digital.library.unt.edu/ark:/67531/metadc30849/
Simulation of Throughput in UMTS Networks with Different Spreading Factors
The authors design and implement a local session admission control (SAC) algorithm for third-generation wireless networks which allows for the simulation of network throughput for different spreading factors and various mobility scenarios. The design of the SAC algorithm uses global information; it incorporates the session arrival rates and the user mobilities across the network and guarantees the users' quality of service as well as pre-specified blocking probabilities. On the other hand, its implementation in each cell uses local information; it only requires the number of sessions currently active in that cell. A global SAC algorithm is also implemented and used as a benchmark since it is inherently optimized and uses global information in making every session admission decision; it yields the best possible performance but has an intensive computational complexity. Using simulation, we determine the network throughput, and show that our optimized local SAC algorithm achieves almost the same performance as our global SAC algorithm at a fraction of the computational cost for pre-specified blocking probabilities and quality of service r4equirements and spreading factor values of 256, 64, 16, and 4. digital.library.unt.edu/ark:/67531/metadc30832/
Strategies for Retention and Recruitment of Women and Minorities in Computer Science and Engineering
This paper describes the efforts and results of a plan for actively recruiting students to undergraduate computer science and engineering programs at the University of North Texas (UNT). It also describes a series of activities aimed at improving retention rates of students already in computer science and engineering programs at UNT. Such recruitment and retention of students is critical to the country's efforts to increase the number of engineering professionals, and is a priority for the Computer Science and Engineering (CSE) Department at UNT. digital.library.unt.edu/ark:/67531/metadc30855/
Subscriber Maximization in CDMA Cellular Networks
This paper discusses subscriber maximization in CDMA cellular networks. The author calculates the maximum number of subscribers in a CDMA cellular network for a given GoS requirement, QoS requirement, network topology, and user distribution profile. The author formulates a constrained optimization problem that maximizes the call arrival rates subject to upper bounds on the blocking probabilities and lower bounds on the bit energy to interference ratios. This paper presents examples for traditional and optimized network topologies with uniform and non-uniform user distribution profiles and different mobility scenarios. digital.library.unt.edu/ark:/67531/metadc30818/
Motivating and Retaining CS2 Students with a Competative Game Programming Project
This article discusses motivating and retaining computer science students with a competitive game programming project. The widespread goals of student retention, introduction larger programming projects and fostering collaboration among students in computer science courses has led to the inclusion of group projects in many curricula, with task division and collaboration as motivation for students to complete assignments. This article presents a study in a first-year programming assignment with similar goals, but with methods adopting the contrarian view - having students directly and individually compete with one another in a tournament of their respective software agents. This article presents the results of a year-long experiment in an intra-class competitive assignment in the second C++ programming course at the University of North Texas in Denton. Metrics of student performance on the assignment, correlation with course grade, student surveys of the project, and retention statistics are presented. Results demonstrating overwhelmingly positive response and high levels of effort among students are submitted, along with remarks on application to student recruiting, retention, and curriculum design. digital.library.unt.edu/ark:/67531/metadc30842/
A Non-Preemptive Scheduling Algorithm for Soft Real-Time Systems
This article discusses a non-preemptive scheduling algorithm for soft real-time systems. Real-time systems are often designed using preemptive scheduling and worst-case execution time estimates to guarantee the execution of high priority tasks. There is, however, an interest in exploring non-preemptive scheduling models for real-time systems, particularly for soft real-time multimedia applications. In this paper, the authors propose a new algorithm that uses multiple scheduling strategies for efficient non-preemptive scheduling of tasks. The goal is to improve the success ratio of the well-known Earliest Deadline First (EDF) approach when the load on the system is very high and to improve the overall performance in both underloaded and overloaded conditions. The authors' approach, known as group EDF (gEDF) is based on dynamic grouping of tasks with deadlines that are very close to each other, and using Shortest Job First (SJF) technique to schedule tasks within the group. The authors present results comparing gEDF with other real-time algorithms including EDF, Best-effort, and Guarantee, by using randomly generated tasks with varying execution times, release times, deadlines and tolerance to missing deadlines, under varying workloads. The authors believe that grouping tasks dynamically with similar deadlines and utilizing a secondary criteria, such as minimizing the total execution time (or other metrics such as power or resource availability) for scheduling tasks within a group, can lead to new and more efficient real-time scheduling algorithms. digital.library.unt.edu/ark:/67531/metadc30824/
Non-Uniform Grid-Based Coordinated Routing in Wireless Sensor Networks
This paper presents a non-uniform grid-based coordinated routing design in wireless sensor networks. The conditions leading to network partition and analysis of energy consumption that prolongs the network lifetime are studied. The authors focus on implementing routing in densely populated sensor networks. By maintaining constant values for parameters such as path loss exponent, receiver sensitivity and transmit power, and varying between uniform and non-uniform grids, we observe energy consumption patterns for each of the grid structures and infer from the network lifetime the better suited grids for uniformly and randomly deployed sensor nodes. digital.library.unt.edu/ark:/67531/metadc30848/
Enhanced Channel Assignment and Load Distribution in IEEE 802.11 WLANs
This paper discusses enhanced channel assignment and load distribution in IEEE 802.11 WLANs. Abstract: An algorithm to reduce congestion and balance users' load in IEEE 802.11b/g wireless local area networks (WLANs) is presented, which takes into account overlapping channel interference between access points (APs) and the signal-to-interference ratio (SIR) experienced by the users. After finding the best channel assignment at the APs, the algorithm then finds the most congested access point (MCAP). It reexamines the users' association with APS by minimizing the congestion at the MCAP. Simulation results show that the proposed algorithm is capable of significantly reducing the overall congestion in the WLAN while mitigating channel interference. Our algorithm has also been shown to be scalable and it performs well for networks of different topologies. digital.library.unt.edu/ark:/67531/metadc30838/
Modeling and Analysis Using Computational Tools
This book chapter presents two special algorithms, Mean Value Analysis and Convolution Algorithm, for the analysis of closed queuing networks, and an introduction to simulation techniques that are widely used in analyzing queuing systems in general. In the illustration of special algorithms, the authors use simplifying assumptions that also show how they provide practical solutions to systems that are interactable or when their behaviors cannot be easily modeled using simple probability distributions. digital.library.unt.edu/ark:/67531/metadc30841/
Real-Time Systems: An Introduction and the State-of-the-Art
This encyclopedia article gives an overview of the broad area of real-time systems. This task is daunting because real-time systems are everywhere, and yet no generally accepted definition differentiates real-time systems from non-real-time systems. The authors make an attempt at providing a general overview of the different classes of real-time systems, scheduling of tasks (or threads) in such systems, design tools and environments for real-time systems, real-time operating systems, and embedded systems. The authors conclude their discussion with research challenges that still remain. digital.library.unt.edu/ark:/67531/metadc30845/
Grid-based Coordinated Routing in Wireless Sensor Networks
This paper discusses grid-based coordinated routing in wireless sensor networks. Abstract: This work explores grid-based coordinated routing in wireless sensor networks and compares the energy available in the network over time for different grid sizes. A test area is divided into square-shaped grids of certain length. Fully charged battery powered nodes are randomly placed in the area with fixed source and sink nodes. One node per grid is elected as the coordinator which does the actual routing. The source node starts flooding the network with every coordinator joining in the routing. Once the flooding reaches the sink node, information is sent back to the source by finding the back route to the source. This process is continued until a node (coordinator) along that route runs out of energy. New coordinators are elected to replace the depleted ones. The source node refloods the network so that the sink can find a new back route to send information. This entire process continues until the network is partitioned and the connectivity between the source and the sink nodes is lost. We explore the quality of service of wireless sensor networks, how the coordinator nodes are elected, and the size of the grid area that will minimize the total energy consumption and extend the lifetime of the network. digital.library.unt.edu/ark:/67531/metadc30839/
Indoor Propagation Modeling at 2.4 GHZ for IEEE 802.11 Networks
This paper discusses indoor propagation modeling. Abstract: The purpose of this study is to characterize the indoor channel for 802.11 wireless local area networks at 2.4 GHz frequency. This work presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include closed corridor, open corridor, classroom, and computer lab. Path loss equations are determined using log-distance path loss model and log-normal shadowing. The Chi-square test statistic values for each access point are calculated to prove that the observed fading is a normal distribution at 5% significance level. A numerical analysis of measurements in each scenario was conducted and the study determined equations that describe path loss for each scenario. digital.library.unt.edu/ark:/67531/metadc30827/
Hybrid Approach for Energy-Aware Synchronization
This book chapter discusses a time synchronization scheme for wireless sensor networks that aims to save sensor battery power while maintaining network connectivity for as long as possible. It focuses on aspects of wireless sensor networks. These include designing a hybrid method between reference broadcast synchronization (RBS) and timing-sync protocol for sensor networks (TPSN) to reduce the number of transmissions required to synchronize an entire network, extending single-hop synchronization methods to operate in large multi-hop networks, verifying that the hybrid methods operate as desired by simulating against RBS and TPSN, and maintaining network connectivity and coverage. digital.library.unt.edu/ark:/67531/metadc30852/
Hybrid Energy-Aware Synchronization Algorithm in Wireless Sensor Networks
This paper discusses hybrid energy-aware synchronization algorithm in wireless sensor networks. Abstract: We present a time synchronization scheme for wireless sensor networks that aims to conserve sensor battery power while maintaining network connectivity for as long as possible. The proposed method creates a hierarchical tree by flooding the sensor network from a designated source point. It then uses a hybrid algorithm derived from the Timing-sync Protocol for Sensor Networks (TSPN) and the Reference Broadcast Synchronization Method (RBS) to periodically synchronize sensor clocks by minimizing the number of required transmissions. In multi-hop ad-hoc networks, a depleted sensor will drop information from all other sensors that route data through it, decreasing the physical area being monitored by the network. It is therefore imperative that time synchronization schemes are aware of the number of sensors being used at any given time. The proposed method uses several techniques and thresholds to maintain network connectivity. A new source point is chosen when the current one's battery power reaches a designated energy threshold. The network is also re-flooded whenever the number of used sensors drops below another threshold. We implement and show that their scheme can provide significant power savings over both TPSN and RBS; the power reduction is even more drastic in large multi-hop sensor networks. The method also improves upon these algorithms by maintaining a large area of coverage even when some sensors lose power. digital.library.unt.edu/ark:/67531/metadc30840/
Global versus Local Call Admission Control in CDMA Cellular Networks
This paper discusses global versus local call admission control. Abstract: We design and implement global and local CAC algorithms for CDMA networks, and compare their network throughput for various mobility scenarios. The global CAC algorithms is inherently optimized and uses global information in making every call admission decision; it yields the best possible performance but has an intensive computational complexity. The design of the local CAC algorithm uses global information but its implementation in each cell uses only local information; it only requires the number of calls currently active in that cell and thus is very simple to implement. We show that our optimized local CAC algorithm achieves almost the same performance as our global CAC algorithm for a given call arrival rate profile. digital.library.unt.edu/ark:/67531/metadc30816/
Impact of Interference Model on Capacity in CDMA Cellular Networks
This paper discusses an impact of interference model on capacity in CDMA cellular networks. Abstract: An overwhelming number of models in the literature use average interference for calculation of capacity of a CDMA network. In this paper, we calculate the actual per-user interference and analyze the effect of user-distribution on the capacity of a CDMA network. We show that even though the capacity obtained using average interference is a good approximation to the capacity calculated using actual interference for a uniform user distribution, the deviation can be tremendously large for non-uniform user distributions. digital.library.unt.edu/ark:/67531/metadc30817/
Intra-Class Competitive Assignments in CS2: A One-Year Study
This paper discusses intra-class competitive assignments in CS2. Abstract: The widespread goals of student retention, introducing larger programming projects, and fostering collaboration among students in computer science courses has led to the inclusion of group projects in many curricula, with task division and collaboration as motivation for students to complete assignments. This paper presents a study in a first-year programming assignment with similar goals, but with methods adopting the contrarian view - having students directly compete with one another in a tournament of their respective software agents. This paper presents the results of a year-long experiment in an intra-class competitive assignment in the second C++ programming course at the University of North Texas in Denton. Metrics of student performance on the assignment, correlation with course grade, student surveys of the project, and retention statistics are presented. Results demonstrating overwhelmingly positive response and high levels of effort among students are submitted, along with remarks on application to student recruiting, retention, and curriculum design. digital.library.unt.edu/ark:/67531/metadc30828/
Multicell CDMA Network Design
Traditional design rules for cellular networks are not directly applicable to code division multiple access (CDMA) networks where intercell interference is not mitigated by cell placement and careful frequency planning. For transmission quality requirements, a minimum signal-to-interface ratio (SIR) must be achieved. The base-station location, its pilot-signal power (which determines the size of the cell), and the transmission power of the mobiles all affect the received SIR. In addition, because of the need for power control in CDMA networks, large cells can cause a lot of interference to adjacent small cells, posing another constraint to design. In order to maximize the network capacity associated with a design, the authors develop a methodology to calculate the sensitivity of capacity to base-station location, pilot-signal power, and transmission power of each mobile. To alleviate the problem caused by difference cell sizes, the authors introduce the power compensation factor, by which the nominal power of the mobiles in every cell is adjusted. The authors then use the calculated sensitivities in an iterative algorithm to determine the optimal locations of the base stations, pilot-signal powers, and power compensation factors in order to maximize capacity. The authors show examples of how networks using these design techniques provide higher capacity than those designed using traditional techniques. digital.library.unt.edu/ark:/67531/metadc30815/
Corpus-based and Knowledge-based Measures of Text Semantic Similarity
Abstract: This paper presents a method for measuring the semantic similarity of texts, using corpus-based and knowledge-based measures of similarity. Previous work on this problem has focused mainly on either large documents (e.g. text classification, information retrieval) or individual words (e.g. synonymy tests). Given that a large fraction of the information available today, on the Web and elsewhere, consists of short text snippets (e.g. abstracts of scientific documents, image captions, product descriptions), in this paper the authors focus on measuring the semantic similarity of short texts. Through experiments performed on a paraphrase data set, the authors show that the semantic similarity method out-performs methods based on simple lexical matching, resulting in up to 13% error rate reduction with respect to the traditional vector-based similarity metric. digital.library.unt.edu/ark:/67531/metadc30981/
A Corpus-based Approach to Finding Happiness
This paper discusses how to locate emotions. Abstract: What are the sources of happiness and sadness in everyday life? In this paper, the authors employ 'linguistic ethnography' to seek out where happiness lies in our everyday lives by considering a corpus of blogposts from the LiveJournal community annotated with happy and sad moods. By analyzing this corpus, the authors derive lists of happy and sad words and phrases annotated by their 'happiness factor'. Various semantic analyses performed with this wordlist reveal the happiness trajectory of a 24-day (3am and 9-10p are most happy), and a 7-day week (Wednesdays are saddest), and compare the socialness and human-centeredness of happy descriptions versus sad descriptions. The authors evaluate our corpus-based approach in a classification task and contrast our wordlist with emotionally-annotated wordlists produced by experimental focus groups. Having located happiness temporally and semantically within this corpus of everyday life, the paper concludes by offering a corpus-inspired livable recipe for happiness. digital.library.unt.edu/ark:/67531/metadc30980/
Cell Design to Maximize Capacity in CDMA Networks
This presentation discusses the code division multiple access (CDMA) inter-cell effects, capacity regions, maximizing network capacity, mobility, a call admission control algorithm, and network performance. digital.library.unt.edu/ark:/67531/metadc30929/
CDMA Network Design
This presentation gives an overview of code-division multiple access (CDMA) and inter-cell effects, network capacities, sensitivity analysis of base station locations, pilot-signal power, and transmission power of the mobiles, and concludes with numerical results. digital.library.unt.edu/ark:/67531/metadc30928/
Capacity Allocations in Multi-cell UMTS Networks for Different Spreading Factors with Perfect and Imperfect Power Control
This presentation discusses user and interference models, wideband code division multiple access (WCDMA) capacity with perfect and imperfect power control, and spreading factors with numerical results. digital.library.unt.edu/ark:/67531/metadc30937/
A Bootstrapping Method for Building Subjectivity Lexicons for Languages with Scarce Resources
Abstract: This paper introduces a method for creating a subjectivity lexicon for languages with scarce resources. The method is able to build a subjectivity lexicon by using a small seed set of subjectivity words, and online dictionary, and a small raw corpus, coupled with a bootstrapping process that ranks new candidate words based on a similarity measure. Experiments performed with a rule-based sentence level subjectivity classifier show an 18% absolute improvement in F-measure as compared to previously proposed semi-supervised methods. digital.library.unt.edu/ark:/67531/metadc31002/
Building Multilingual Semantic Networks with Non-Expert Contributions over the Web
This paper discusses building multilingual semantic networks. Abstract: We present a system that allows non-expert Web users to contribute towards building a multilingual lexical resource. Our study focuses on the Romanian-English language pair, and the target resource is a Romanian WordNet strongly connected to the English WordNet. We use a bilingual dictionary, a monolingual definition dictionary and documents on the Web to build synsets, attach them a gloss, and provide some examples. The results of the semi-automatic acquisition system are judged by two human judges, and they are compared to automatic approaches to building a Romanian WordNet. digital.library.unt.edu/ark:/67531/metadc30947/
PicNet: Augmenting Semantic Resources with Pictorial Representations
In this paper, the authors introduce PicNet, a Web-based system for augmenting semantic resources with illustrative images using volunteer contributions over the Web. PicNet seeks to build rich knowledge-bases that encode word/image associations, to the end of combining the advantages and power of both visual and linguistic representations as means of defining world concepts. In this paper, the authors address some of the issues encountered in identifying prototypical illustrations for various concepts, as well as issues related to the construction of such pictorial knowledge-bases with the help of Web users. digital.library.unt.edu/ark:/67531/metadc30972/
Amazon Mechanical Turk for Subjectivity Word Sense Disambiguation
This paper discusses word sense disambiguation. Abstract: Amazon Mechanical Turk (MTurk) is a marketplace for so-called "human intelligence tasks" (HITs), or tasks that are easy for humans but currently difficult for automated processes. Providers upload tasks to MTurk which workers then complete. Natural language annotation is one such human intelligence task. In this paper, the authors investigate using MTurk to collect annotations for Subjectivity Word Sense Disambiguation (SWSD), a course-grained word sense disambiguation task. The authors investigate whether they can use MTurk to acquire good annotations with respect to gold-standard data, whether they can filter out low-quality workers (spammers), and whether there is a learning effect associated with repeatedly completing the same kind of task. While our results with respect to spammers are inconclusive, the authors are able to obtain high-quality annotations for the SWSD task. These results suggest a greater role for MTurk with respect to constructing a large scale SWSD system in the future, promising substantial improvement in subjectivity and sentiment analysis. digital.library.unt.edu/ark:/67531/metadc31023/
An Algorithm for Open Text Semantic Parsing
Abstract: This paper describes an algorithm for open text shallow semantic parsing. The algorithm relies on a frame dataset (FrameNet) and a semantic network (WordNet), to identify semantic relations between words in open text, as well as shallow semantic features associated with concepts in the text. Parsing semantic structures allows semantic units and constituents to be accessed and processed in a more meaningful way than syntactic parsing, moving the automation of understanding natural language text to a higher level. digital.library.unt.edu/ark:/67531/metadc30953/
Classifier Stacking and Voting for Text Filtering
Abstract: This paper summarizes the approach and the results of the TextCat system participating in the Filtering track in the Text Retrieval Conference 2002. The system relies primarily on statistical methods, and was designed with the main purpose of having a backbone system in which we can further integrate semantic components, and evaluate their relative performance as compared to traditional statistical approaches. They system is therefore simple, and is based on techniques for keywords extraction, and various classifier combinations including stacking and voting. TextCat participated in the Batch and Routing tasks. In the Batch task, it achieved a score of 39.02% normalized utility, and 26.37% F-measure respectively, averaged over all topics. The averaged uninterpolated precision for our best routing submission was 14.16%. digital.library.unt.edu/ark:/67531/metadc30942/
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