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Cleveland State University

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Full-Text Articles in Systems and Communications

Randomcast: An Energy-Efficient Communication Scheme For Mobile Ad Hoc Networks, Sunho Lim, Chansu Yu, Chita R. Das Aug 2009

Randomcast: An Energy-Efficient Communication Scheme For Mobile Ad Hoc Networks, Sunho Lim, Chansu Yu, Chita R. Das

Electrical and Computer Engineering Faculty Publications

In mobile ad hoc networks (MANETs), every node overhears every data transmission occurring in its vicinity and thus, consumes energy unnecessarily. However, since some MANET routing protocols such as dynamic source routing (DSR) collect route information via overhearing, they would suffer if they are used in combination with 802.11 PSM. Allowing no overhearing may critically deteriorate the performance of the underlying routing protocol, while unconditional overhearing may offset the advantage of using PSM. This paper proposes a new communication mechanism, called RandomCast, via which a sender can specify the desired level of overhearing, making a prudent balance between energy and …

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Selective Advance Reservations Based On Host Movement Detection And Resource-Aware Handoff, Kyounghee Lee, Myungchul Kim, Chansu Yu, Ben Lee, Seungphil Hong Mar 2006

Selective Advance Reservations Based On Host Movement Detection And Resource-Aware Handoff, Kyounghee Lee, Myungchul Kim, Chansu Yu, Ben Lee, Seungphil Hong

Electrical and Computer Engineering Faculty Publications

This paper proposes a new mechanism, which addresses the excessive advance reservation requirements of QoS guarantee methods for mobile Internet. To save resources for excessive advance reservations, the proposed mechanism employs a movement detection scheme for a mobile host (MH) using link-layer functionalities. With the movement detection scheme, advance reservations can be established at only where a MH is likely to visit soon. Another novel feature of our mechanism is resource-aware handoff direction scheme that allows a MH to choose its next BS according to not only the link-layer signal strength, but also the available amount of …

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Study Of Behavior Of Digital Modulations For Beam Steerable Reflectarray Antennas, Fuqin Xiong, Robert R. Romanofsky Mar 2005

Study Of Behavior Of Digital Modulations For Beam Steerable Reflectarray Antennas, Fuqin Xiong, Robert R. Romanofsky

Electrical and Computer Engineering Faculty Publications

This paper investigates the bit error rate (BER) performance of digital modulations in a system with a scanning reflectarray antenna. A reflectarray causes intersymbol interference (ISI) in a digitally modulated signal, its phase shifters' phase errors cause signal distortion, and its phase shifters' phase transient causes beam pattern degradation during direction switching. In this paper, composite signal models of the reflectarray are established for both static and transient states. Due to different feed-to-element distances and the element-to-observation distances, different delays exist in signal components. These delays cause ISI whose effect is analyzed and evaluated. Effects of phase shifters' phase errors …

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Design Of A Satellite Cluster System In Distributed Simulation, Jong Sik Lee, Thong Luu, Vijaya K. Konangi Jan 2005

Design Of A Satellite Cluster System In Distributed Simulation, Jong Sik Lee, Thong Luu, Vijaya K. Konangi

Electrical and Computer Engineering Faculty Publications

This article presents the design and development of a satellite cluster system that supports an interfederation communication in High Level Architecture (HLA)-compliant distributed simulation. The interfederation communication enables the execution of a complex, large-scale cluster system of distributed satellites that share the dispersed data assets among satellite components collaboratively. After a brief review of the HLA bridge for interfederation communication, the authors discuss the design issues related to a satellite cluster system that provides cluster management, interfederation communication, and communication data management. They analyze system performance and scalability for centralized and decentralized configurations. The empirical results on the heterogeneous …

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Oci-Based Group Communication Support In Corba, Dongman Lee, Dukyun Nam, Hee Yong Youn, Chansu Yu Nov 2003

Oci-Based Group Communication Support In Corba, Dongman Lee, Dukyun Nam, Hee Yong Youn, Chansu Yu

Electrical and Computer Engineering Faculty Publications

Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a …

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M-Ary Amplitude Shift Keying Ofdm System, Fuqin Xiong Oct 2003

M-Ary Amplitude Shift Keying Ofdm System, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

Coherent M-ary amplitude-shift keying (MASK) is proposed for use in orthogonal frequency-division multiplexing (OFDM) systems. The frequency separation between subcarriers is only 1/2T instead of 1/T. With a slightly wider bandwidth, an √M-ary ASK OFDM can achieve the same bit-error rate (BER) of M-ary quadrature amplitude modulation (QAM) OFDM and a better BER than that of M-ary phase-shift keying (MPSK) OFDM. The √M-ary ASK OFDM has the same peak-to-average-power ratio as that of the M-ary QAM OFDM. The MASK OFDM can be implemented digitally and efficiently by fast cosine transform and demodulated by inverse fast cosine transform. Comparisons show that …

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Coding, Decoding, And Recovery Of Clock Synchronization In Digital Multiplexing System, Hansheng Wang, Xiaoyi Qin, Lieguang Zeng, Fuqin Xiong May 2003

Coding, Decoding, And Recovery Of Clock Synchronization In Digital Multiplexing System, Hansheng Wang, Xiaoyi Qin, Lieguang Zeng, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

High-speed broadband digital communication networks rely on digital multiplexing technology where clock synchronization, including processing, transmission, and recovery of the clock, is the critical technique. This paper interprets the process of clock synchronization in multiplexing systems as quantizing and coding the information of clock synchronization, interprets clock justification as timing sigma-delta modulation (TΔ-ΣM), and interprets the jitter of justification as quantization error. As a result, decreasing the quantization error is equivalent to decreasing the jitter of justification. Using this theory, the paper studies the existing jitter-reducing techniques in transmitters and receivers, presents some techniques that can decrease the quantization error …

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Planar Approximation For The Least Reliable Bit Log-Likelihood Ratio Of 8-Psk Modulation, William H. Thesling, Fuqin Xiong, M. J. Vanderaar Jun 2000

Planar Approximation For The Least Reliable Bit Log-Likelihood Ratio Of 8-Psk Modulation, William H. Thesling, Fuqin Xiong, M. J. Vanderaar

Electrical and Computer Engineering Faculty Publications

The optimum decoding of component codes in block coded modulation (BCM) schemes requires the use of the log-likelihood ratio (LLR) as the signal metric. An approximation to the LLR for the least reliable bit (LRB) in an 8-PSK modulation based on planar equations with fixed-point arithmetic is developed that is both accurate and easily realisable for practical BCM schemes. Through an error power analysis and an example simulation it is shown that the approximation results in less than 0.06 dB in degradation over the exact expression at an Es/N0 of 10 dB. It is also shown that …

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A Worst-Case Analysis Of Direct-Sequence Spread-Spectrum In Multipath Channels, Murad Hizlan, Xuedong Liu May 1999

A Worst-Case Analysis Of Direct-Sequence Spread-Spectrum In Multipath Channels, Murad Hizlan, Xuedong Liu

Electrical and Computer Engineering Faculty Publications

We consider a direct-sequence spread-spectrum system operating in an indoors environment in the presence of multiaccess and multipath interference, and additive white Gaussian noise. We focus on the worst-case bit error probability of this system with a constraint on signal-to-interference ratio, and derive a Chernoff-type upper bound on this error probability. We evaluate the upper bound for a special case in order to gain understanding of the basic worst-case performance. We also compare the effects of the worst-case multipath interference with those of the worst-case multiuser interference of …

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Worst-Case Error Probability Of A Spread-Spectrum System In Energy-Limited Interference, Murad Hizlan, Brian L. Hughes Feb 1998

Worst-Case Error Probability Of A Spread-Spectrum System In Energy-Limited Interference, Murad Hizlan, Brian L. Hughes

Electrical and Computer Engineering Faculty Publications

We consider a communication channel corrupted by thermal noise and by an unknown and arbitrary interference of bounded energy. For this channel, we derive a simple upper bound to the worst-case error probability suffered by a direct sequence (DS) communication system with error-correction coding, pseudorandom interleaving, and a correlation receiver. This bound is exponentially tight as the block length of the error correcting code becomes large. Numerical examples are given that illustrate the dependence of the bound on the choice of error correcting code, the type of interleaving used, and the relative energy of the Gaussian noise and arbitrary interference

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Performance Of Mhpm In Rician And Rayleigh Fading Mobile Channels, Fuqin Xiong, S Bgatnyket Mar 1997

Performance Of Mhpm In Rician And Rayleigh Fading Mobile Channels, Fuqin Xiong, S Bgatnyket

Electrical and Computer Engineering Faculty Publications

This paper evaluates the error probability of the rectangular frequency pulse multi-h modulation (MHPM) scheme in slowly-fading, frequency-nonselective or frequency-selective Rician and Rayleigh channels. The evaluation is performed with a method combining analysis and computer simulation. Performance degradations are evaluated for various direct-to-reflected signal ratio, Doppler shifts, and relative time delays in Rician fading channels. Compared with minimum shift keying (MSK), MHPM schemes appear to have retained their coding gains

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A Cascadable Pragmatic Block Decoding Algorithm Exploiting Channel Measurement Information, William H. Thesling, Fuqin Xiong Jul 1996

A Cascadable Pragmatic Block Decoding Algorithm Exploiting Channel Measurement Information, William H. Thesling, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

The complexity of algorithms to perform soft decision decoding on block codes has impeded their inclusion in practical systems. A well-known class of algorithms for decoding block codes utilizing channel measurement information along with the algebraic properties of the code are the Chase algorithms.1 In this paper a decoding method similar to Chase's third algorithm is presented. However, in this method, a single test pattern or alternate codeword makes up one stage of the decoder. The method uses information from the previous decoding(s) to assist in generating a test pattern. This single stage ‘Second Chance Algorithm’ can then be …

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