Computer Engineering Commons^™

Throughput And Delay In Wireless Sensor Networks Using Directional Antennas, Hong-Ning Dai

Hong-Ning Dai

Most of studies only consider that wireless sensor networks are equipped with only omni-directional antennas, which can cause high collisions. It is shown that the per node throughput in such networks is decreased with the increased number of nodes. Thus, the transmission with multiple short-range hops is preferred to reduce the interference. However, other studies show that the transmission delay increases with the increased number of hops.

In this paper, we consider using directional antennas in wireless sensor networks. We have found that using directional antennas not only can increase the throughput capacity but also can decrease the delay by …

Collision-Tolerant Transmission With Narrow-Beam Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu, Bo Li

Hong-Ning Dai

The application of directional antennas in wireless ad hoc networks brings numerous benefits, such as increased spatial reuse and mitigated interference. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless ad hoc networks using omni-directional antennas. However, RTS/CTS frames cannot mitigate the interference completely. Besides, they also contribute a lot to the performance overhead. This paper studies the problem from a new perspective. We have found that the transmission success probability under directional transmission and directional reception is quite high when the antenna beamwidth is quite narrow. Motivated by the analytical results, …

A Framework For Evaluating Managerial Styles In Open Source Projects, Tony Wasserman, Eugenio Capra

Tony Wasserman

This paper presents the Software Project Governance Framework (SPGF) for characterizing management of software projects, based on mechanisms used for communication and collaboration, the organizational structure of projects, and testing and quality assurance procedures. The framework was developed and validated from interviews and surveys with leaders of more than 70 commercial and community based software projects, including both closed and open source projects.

On Collision-Tolerant Transmission With Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

The application of directional antennas in wireless networks brings numerous benefits, such as increased spatial reuse and mitigated interferences. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless networks using omni-directional antennas. However, RTS/CTS frames cannot mitigate the interfering nodes completely. Besides, they also contribute a lot to the performance overhead. This paper studies the problem from a new perspective. We analyze the transmission success probability under directional transmission and directional reception when the antenna beamwidth is quite narrow. Motivated by the analytical results, we design a lightweight MAC protocol without RTS/CTS …

On The Capacity Of Multi-Channel Wireless Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Raymond Chi-Wing Wong, Min-You Wu

Hong-Ning Dai

The capacity of wireless ad hoc networks is affected by two key factors: the interference among concurrent transmissions and the number of simultaneous transmissions on a single interface. Recent studies found that using multiple channels can separate concurrent transmissions and greatly improve network throughput. However, those studies only consider that wireless nodes are equipped with only omnidirectional antennas, which cause high collisions. On the other hand, some researchers found that directional antennas bring more benefits such as reduced interference and increased spatial reuse compared with omnidirectional antennas. But, they only focused on a single-channel network which only allows finite concurrent …

Diagnosing Faults In Electrical Power Systems Of Spacecraft And Aircraft, Ole J. Mengshoel, Adnan Darwichse, Keith Cascio, Mark Chavira, Scott Poll, Serdar Uckun

Ole J Mengshoel

Electrical power systems play a critical role in spacecraft and aircraft. This paper discusses our development of a diagnostic capability for an electrical power system testbed, ADAPT, using probalistic techniques. In the context of ADAPT, we present two challenges, regarding modelling and real-time performance, often encountered in real-world diagnostic applications. To meet the modelling challenge, we discuss our novel high-level specification language which supports auto-generation of Bayesian networks. To meet the real-time challenge, we compile Bayesian networks intro arithmetic circuits. Arithmetic circuits typically have small footprints and are optimized for the real-time avionics systems found in spacecraft and aircraft. Using …

Evaluating Software Engineering Processes In Commercial And Community Open Source Projects, Tony Wasserman, Eugenio Capra

Tony Wasserman

We describe a current study for obtaining information about management of commercial and community open source projects. We have interviewed and surveyed leaders of more than 75 open source projects. Questions focused on the styles of leadership and communication, with a technical focus on testing and quality assurance processes. This paper describes the methods used to identify and contact subjects, as well as the questions posed and some results.

Using Flossmole Data In Determining Business Readiness Ratings, Tony Wasserman, Ashutosh Das

Tony Wasserman

This paper is a preliminary report on using FLOSSmole data retrieved from open source repositories (forges) to calculate Business Readiness Rating scores.

Methods And Tools For Developing Interactive Information Systems: An Historical Perspective, Tony Wasserman

Tony Wasserman

This paper describes the evolution of hardware and software technology over the past three decades, focusing on approaches for building interactive information systems and web applications. Successive generations of technology have used advances in hardware and software technology, along with increasingly sophisticated development methods and tools, to reduce development times and to produce a better user experience. After describing the key technology characteristics of each generation, this paper also describes the evolution of a specific methodology, User Software Engineering, from its origins in the 1970’s to its applicability to the development of modern applications.

A Busy-Tone Based Mac Scheme For Wireless Ad Hoc Networks Using Directional Antennas, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Applying directional antennas in wireless ad hoc networks offers numerous benefits, such as extended communication range, increased spatial reuse, improved capacity and suppressed interference. However, directional antennas can cause new location-dependent carrier sensing problems, such as new hidden terminal and deafness problems, which can cause severe penalties to the performance. Recently, a few schemes have been proposed to tackle these problems. However, these methods can provide limited solutions on the hidden terminal and deafness problems. We propose a new MAC protocol, termed the busy-tone based directional medium access control (BT-DMAC) protocol. When the transmission is in progress, the sender and …

Pathologyxgrid Implementation For The Interproscan Bioinformatics Software, Cody K. Bumgardner

Cody Bumgardner

SoftwareInterProScan is an essential step in the Epichloëfestucae genome project’s pipeline. Complete determination of the genome sequence for Epichloëfestucae, requires substantial programmatic and computing efforts. Due to the running time requirements the computational volume of some of its subtasks exceed the power of a traditional single processor computation and high performance approaches, such as grid computing, are needed.

An Overview Of Mac Protocols With Directional Antennas In Wireless Ad Hoc Networks, Hong-Ning Dai, Kam-Wing Ng, Min-You Wu

Hong-Ning Dai

Although directional antennas have been used in mobile communications systems for quite a long time, realistic applications of directional or smart antennas in wireless ad hoc network have emerged just in recent years. Directional antennas provide numerous benefits, such as higher gains, increased transmission range and low interferences. Wireless medium access schemes play a crucial role in ensuring the efficient and fair sharing of wireless resources. Therefore there are many research work on mechanisms at the wireless medium access layer by using directional antennas. The new features of MAC with directional antennas can cause not only location dependent carrier sensing …

The Case For Thoroughly Testing Complex System Dynamic Models

Wayne W. Wakeland

In order to determine whether model testing is as useful as suggested by modeling experts, the full battery of model tests recommended by Forrester, Senge, Sterman, and others was applied retrospectively to a complex previously-published system dynamics model. The time required to carry out each type of test was captured, and the benefits that resulted from applying each test was determined subjectively. The resulting benefit to cost ratios are reported. These ratios suggest that rather than focusing primarily on sensitivity testing, modelers should consider other types of model tests such as extreme condition tests and family member tests. The study …

Mil-Std-188-125-1, High-Altitude Emp Protection For Fixed Ground-Based Facilities

George H Baker

MIL-STD-188-125-1 establishes minimum requirements and design objectives for high-altitude electromagnetic pulse (HEMP) hardening of fixed ground-based facilities that perform critical, time-urgent command, control, communications, computer, and intelligence (C4I) missions. The standard prescribes minimum performance requirements for low-risk protection from mission-aborting damage or upset due to HEMP environments. It also addresses minimum testing requirements for demonstrating that prescribed performance has been achieved and for verifying that the installed protection subsystem provides the operationally required hardness for the completed facility. Covered fixed ground-based facility types include subscriber terminals and data processing centers, transmitting and receiving communications stations, and relay facilities. Use of …

Data Communication Software- Role And Functions, Raman K. Attri, Noor Jahan Haque

Raman K. Attri

The shifting of communication systems from analog to digital has introduces a new area of data communication. The core of data communication is Communication software which is the topic of my paper today. In this paper I shall cover following areas: Overview of Data Communication, Role of Data Communication Software, Functional Aspects of Data Communication Software

Software Tool For Seismic Data Recorder And Analyser, Satish Kumar, Raman Attri, B. Sharma, M. Shamshi

Raman K. Attri

Design and Development of software controlled stand-alone instruments has been identified as the most vital component of national and intemational programs on earthquake hazard and risk management. For in depth investigation and studies, the development of precise instruments designed around computer is emerging very fast. Interacing of personal computer with seismic instrument is an important design task. A design technique based on minimum hardware has been worked out around the parallel printer interface of computer. Hardware and Software for this purpose has been designed to make the instrument interact with computer through parallel port interface. Incorporation of software for seismic …