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Full-Text Articles in Computer Engineering

Adaptive Turn-Prohibition Routing Algorithm For The Networks Of Workstations, Amey Bhaskar Shevtekar Dec 2003

Adaptive Turn-Prohibition Routing Algorithm For The Networks Of Workstations, Amey Bhaskar Shevtekar

Theses

Deadlock occurrence is a critical problem for any computer network. Various solutions have been proposed over last two decades to solve problem of deadlocks in networks using different routing schemes, like up/down routing algorithm used in Myrinet switches. However, most of existing approaches for deadlock-free routing either try to eliminate any possibility of deadlock occurrence, which can result in putting extra restrictions on the routing in the networks or put no restrictions on routing, which leads to other approach namely deadlock recovery. In this thesis emphasis is on developing hybrid approach for routing in wormhole networks, wherein some prohibition ...


Combined Beamforming And Space-Time Block Coding With A Sparse Array Antenna, Robert H. Morelos-Zaragoza, Mohammad Ghavami Oct 2003

Combined Beamforming And Space-Time Block Coding With A Sparse Array Antenna, Robert H. Morelos-Zaragoza, Mohammad Ghavami

Robert Henry Morelos-Zaragoza

In this paper, we continue our investigation of joint beamforming and transmit diversity with space-time block coding. In particular, the performance of a four-element array antenna is considered, in the context of an indoor wireless communication system. The main contribution is to show that transmit diversity may be practically achieved, even with correlated beams produced by a sparse array antenna.


Combined Beamforming And Space-Time Block Coding With Sparse Array Antennas, Robert H. Morelos-Zaragoza Oct 2003

Combined Beamforming And Space-Time Block Coding With Sparse Array Antennas, Robert H. Morelos-Zaragoza

Robert Henry Morelos-Zaragoza

In this paper, the combination of beamforming and space-time block coding is investigated. An adaptive scheme for the assignment of transmission beams is proposed. Data for the determination of beams are obtained using a triangular switch-beam array antenna at the transmitter. The number of peak points is determined from the data and a prescribed threshold level. Orthogonal space-time block coding is then applied to the transmission beams. We examine the distribution of the number of assigned beams as a function of indoor wireless channel parameters. Also, the effects of a small number of array elements and associated correlated beams, and ...


Low Interference Routing For Wireless Ad-Hoc Networks, Mohit Gupta Aug 2003

Low Interference Routing For Wireless Ad-Hoc Networks, Mohit Gupta

Theses

In this thesis the primary focus is on the problem of interference between messages. The thesis discusses why the messages are blocked in a system? How adding a message impacts the cost of all other available links, which can be established in the system.

This thesis analyzes how the availability of channels, increase in number of nodes and increase in the transmission range help in increasing the number of messages that can be handled in the network. It is also analyzes how critical is the selection of the maximum transmission range MTR, transmission range TR and required transmission range RTR ...


Hop-Limited Routing For Multihop Cellular Networks, Cem Dincer May 2003

Hop-Limited Routing For Multihop Cellular Networks, Cem Dincer

Theses

In recent years, conventional cellular systems have experienced evolution in fields of data oriented services. During this period, the requirement for high data-rate stimulated new research proposals, which resulted in a new architecture: Multihop Cellular Networks (MCN), where multihop structure enables mobile stations to forward packets from other mobile stations to the base station on the uplink, and in turn, forward packets to other mobile stations from the base station on the downlink. In this thesis, a new routing algorithm is introduced for MCNs in order to limit the number of hops between the base station and the mobile stations ...


Reduction Of False Positives In Fault Detection System Using A Low Pass Data Filter, Ranjit Salunkhe May 2003

Reduction Of False Positives In Fault Detection System Using A Low Pass Data Filter, Ranjit Salunkhe

Theses

Network traffic is bursty in nature and exhibits the property of self-similarity, the degree of which is measured by the Hurst parameter. Now, in any network there is always the possibility of the occurrence of fault traffic that can be caused due to faults or malfunction of a network component. Fault Detection Systems that check for traffic anomalies can trigger off an alert on the detection of any traffic behavior that deviates from normal. Such deviation is usually caused when a fault occurs. But in network traffic sudden bursts may occur due to the inherent behavior of a network application ...


Intrusion Detection System For Ad Hoc Mobile Networks Using Neighborhood Watch Theory, Ramani Rajagopalan May 2003

Intrusion Detection System For Ad Hoc Mobile Networks Using Neighborhood Watch Theory, Ramani Rajagopalan

Theses

This study describes several experiments to simulate and study temperature sensor networks. The ultimate goal of this study is to accurately predict a temperature sensor failure in a sensor network, using Network Neighborhood Watch theory. Simulated temperature measurements are used to compare the results of accuracy, and quickness in detecting a failure in a malfunctioning sensor node. This is done by changing the intervals between temperature sampling, by considering different rates of temperature raise, as well as varying the number of nodes in the network neighborhood (deployment density). The thesis studies the threshold for temperature sensor failure by computing a ...


The Rise And Demise Of The Technology-Specific Approach To The First Amendment, Christopher S. Yoo Jan 2003

The Rise And Demise Of The Technology-Specific Approach To The First Amendment, Christopher S. Yoo

Faculty Scholarship at Penn Law

No abstract provided.


Report On The Third Acm/Ieee Joint Conference On Digital Libraries (Jcdl), Michael L. Nelson Jan 2003

Report On The Third Acm/Ieee Joint Conference On Digital Libraries (Jcdl), Michael L. Nelson

Computer Science Faculty Publications

The Third ACM/IEEE Joint Conference on Digital Libraries (JCDL 2003) was held on the campus of Rice University in Houston, Texas, May 27 - 31. Regarding the merging of the ACM and IEEE conference series, in the JCDL 2002 conference report published last year in D-Lib Magazine Edie Rasmussen noted, "Perhaps by next year...no one will remember that it wasn't always so" [1]. Judging by the number of participants I met who did not know that the ACM and IEEE used to hold separate digital library conferences, Rasmussen's prediction has come to pass.


A Framework For Aggregating Network Performance In Distributed Brokering Systems, Gurhan Gunduz, Shrideep Pallickara, Geoffrey C. Fox Jan 2003

A Framework For Aggregating Network Performance In Distributed Brokering Systems, Gurhan Gunduz, Shrideep Pallickara, Geoffrey C. Fox

Electrical Engineering and Computer Science

The Internet is presently being used to support increasingly complex interaction models as a result of more and more applications, services and frameworks becoming network-centric. Efficient utilization of network and networked resources is of paramount importance. Network performance gathering is a precursor to any scheme that seeks to provide adaptive routing capabilities for interactions. In this paper we present a network performance aggregation framework that is extensible and appropriate for distributed messaging systems that span multiple realms, disparate communication protocols and support different applications.


New Models Of Regulation And Interagency Governance, Christopher S. Yoo Jan 2003

New Models Of Regulation And Interagency Governance, Christopher S. Yoo

Faculty Scholarship at Penn Law

No abstract provided.


Access To Networks: Economic And Constitutional Connections, Daniel F. Spulber, Christopher S. Yoo Jan 2003

Access To Networks: Economic And Constitutional Connections, Daniel F. Spulber, Christopher S. Yoo

Faculty Scholarship at Penn Law

No abstract provided.


Frequency-Hopped Multiple-Access Communications With Noncoherent M-Ary Ofdm-Ask, A. Al-Dweik, Fuqin Xiong Jan 2003

Frequency-Hopped Multiple-Access Communications With Noncoherent M-Ary Ofdm-Ask, A. Al-Dweik, Fuqin Xiong

Electrical Engineering & Computer Science Faculty Publications

A noncoherent, bandwidth-efficient modulation scheme is proposed for frequency-hopping multiple-access (FH-MA) networks. The proposed scheme is a combination of noncoherent M-ary amplitude-shift keying (NMASK) and orthogonal frequency-division multiplexing (OFDM). Using this scheme minimizes the required data bandwidth. The number of frequency slots available to the users increases significantly for a fixed spread-spectrum bandwidth (BWSS). The effect of the multiple-access interference is reduced. Simple and accurate bit error rate expressions have been derived for FH-OFDM-MASK in additive white Gaussian noise channels and for FH-OFDM-ASK in Rayleigh fading channels.


Wireless Local Area Network Security : An Investigation Into Security Tool Usage In Wireless Networks, Susan Webb Jan 2003

Wireless Local Area Network Security : An Investigation Into Security Tool Usage In Wireless Networks, Susan Webb

Theses : Honours

Many organisations and individuals installing wireless local area networks (WLANs), which are based on the IEEE 802.11 b standard, have little understanding of the security issues that surround this technology.

This study was initiated to determine how WLAN security issues affect organisations in Perth, Western Australia. The scope of the study was restricted to 802.llb WLANs operating in infrastructure mode, where all traffic is transmitted by wireless access points (APs). This study was conducted in two phases. The general aims of the first phase were to determine the number of detectable WLANs in the Perth Central Business District ...


The Mediated Data Integration (Medint) : An Approach To The Integration Of Database And Legacy Systems, Suvimol Mukviboonchai Jan 2003

The Mediated Data Integration (Medint) : An Approach To The Integration Of Database And Legacy Systems, Suvimol Mukviboonchai

Theses: Doctorates and Masters

The information required for decision making by executives in organizations is normally scattered across disparate data sources including databases and legacy systems. To gain a competitive advantage, it is extremely important for executives to be able to obtain one unique view of information in an accurate and timely manner. To do this, it is necessary to interoperate multiple data sources, which differ structurally and semantically. Particular problems occur when applying traditional integration approaches, for example, the global schema needs to be recreated when the component schema has been modified. This research investigates the following heterogeneities between heterogeneous data sources: Data ...