Computer & Electronics Engineering Faculty Publications Copyright (c) 2013 University of Nebraska - Lincoln All rights reserved. http://digitalcommons.unl.edu/computerelectronicfacpub Recent documents in Computer & Electronics Engineering Faculty Publications en-us Sun, 28 Apr 2013 01:30:36 PDT 3600 Timing accuracy of self-encoded spread spectrum navigation with communication http://digitalcommons.unl.edu/computerelectronicfacpub/108 http://digitalcommons.unl.edu/computerelectronicfacpub/108 Fri, 26 Apr 2013 11:17:46 PDT The author presents the timing accuracy of self-encoded spread spectrum (SESS) in navigation. SESS eliminates the need for traditional transmit and receive pseudo noise code generators. As the term implies, the spreading code is instead obtained from the random digital information source itself. SESS was shown to improve system performance significantly in fading channels. In this study, the authors investigate the timing accuracy of SESS in comparison to m-sequence and Gold code. SESS can be an excellent candidate for navigation with communication.

]]> Won Mee Jang Priority Preemption for Real-time Application QoS Guarantees in Cooperative Vehicular Networks http://digitalcommons.unl.edu/computerelectronicfacpub/107 http://digitalcommons.unl.edu/computerelectronicfacpub/107 Mon, 15 Oct 2012 11:58:41 PDT Inter-vehicle and roadside-to-vehicle communications can contribute to a safer and more efficient driving experience by providing time-sensitive and location-aware information. However, its performance suffers from vehicle mobility, intermittent user connectivity, and wireless channel unreliability. In this paper, we propose a novel cross-layer optimization approach based on our Adaptive Distributed Cooperative Medium Access Control (ADC-MAC) protocol to guarantee the quality-of-service (QoS) of real-time applications. Markov chain based theoretical analysis show that our proposed priority preemption approach can improve the quality of a real-time application by guaranteeing its bandwidth and reducing its transmission latency.

]]> Ting Zhou et al. Priority Preemption for Real-time Application QoS Guarantees in Cooperative Vehicular Networks http://digitalcommons.unl.edu/computerelectronicfacpub/106 http://digitalcommons.unl.edu/computerelectronicfacpub/106 Mon, 15 Oct 2012 11:42:38 PDT Inter-vehicle and roadside-to-vehicle communications can contribute to a safer and more efficient driving experience by providing time-sensitive and location-aware information. However, its performance suffers from vehicle mobility, intermittent user connectivity, and wireless channel unreliability. In this paper, we propose a novel cross-layer optimization approach based on our Adaptive Distributed Cooperative Medium Access Control (ADC-MAC) protocol to guarantee the quality-of-service (QoS) of real-time applications. Markov chain based theoretical analysis show that our proposed priority preemption approach can improve the quality of a real-time application by guaranteeing its bandwidth and reducing its transmission latency.

]]> Ting Zhou et al. Message from the Chair of Technical Program Committee http://digitalcommons.unl.edu/computerelectronicfacpub/105 http://digitalcommons.unl.edu/computerelectronicfacpub/105 Mon, 15 Oct 2012 11:41:01 PDT On behalf of all the members of the Organizing Committee, I would like to welcome you to the 5th International Conference on Signal Processing and Telecommunication Systems, ICSPCS’2011. The ICSPCS conferences evolved from the series of successful symposia and workshops, i.e. International Symposia on DSP and Communication Systems (DSPCS), and Workshops on the Internet, Telecommunications and Signal Processing (WITSP). As in the past, the Organizing Committee has succeeded this year in achieving an official technical co-sponsorship of the IEEE Communications Society for conference. As a result the ICSPCS’2011 conference has been listed in the IEEE database of the conferences and the proceedings will be published in IEEE Xplore.

This year response to the call for papers was very good, with 223 full paper submissions. All submitted papers have been put through a rigorous peer review process, and each paper received at least two but often three or more peer reviews. Based on those reviews, 83 papers have been accepted, and finally 81 included in the program – 48 for oral and 33 for poster presentations. To complement the program, the Organizing Committee invited a keynote speaker, Dr. Thaddeus Owens Walker III of United States Naval Academy. His address: Securing Wireless in the Cyberdomain will be a great addition to the already excellent program.

At this point, I wish to thank the authors who put so many efforts, first in preparing their manuscripts for submission, and then for incorporating reviewers’ comments in the camera-ready papers. I extend my sincere thanks to the 68 members of the Technical Program Committee for organizing reviews for the submitted papers, and 222 reviewers for thorough reviews of the manuscripts.

I hope that you will take pleasure in staying in Waikiki Beach whose friendly atmosphere will facilitate peer-to-peer interactions and networking and be a pleasant supplement to the research benefits of the Conference.

]]> Tadeusz Wysocki Prof. Dr. Marek E. Bialkowski (1951 – 2011) http://digitalcommons.unl.edu/computerelectronicfacpub/104 http://digitalcommons.unl.edu/computerelectronicfacpub/104 Mon, 15 Oct 2012 11:39:58 PDT It is our sad duty to report the untimely death of Prof. Dr. Marek E. Bialkowski, who passed away on Thursday, October 27, 2011 after a short unexpected illness caused by pneumonia. He was a remarkable researcher and a mentor and friend to many us and he will be greatly missed.

Marek was born in Sochaczew, Poland, in 1951. He received the M.Eng.Sc. degree in applied mathematics and the Ph.D. degree in electrical engineering, both from the Warsaw University of Technology, Warsaw, Poland, in 1974 and 1979, respectively. He received the Doctor of Engineering (higher doctorate) degree in computer science and electrical engineering from the University of Queensland, Brisbane, Australia, in 2000. He was a Chair Professor in the School of Information Technology and Electrical Engineering at the University of Queensland.

He held teaching and research appointments at universities in Poland, Ireland, Australia, UK, Canada, Singapore, Hong Kong, and Switzerland. In 1977, he joined the Institute of Radio Electronics, Warsaw University of Technology and, in 1979, became an Assistant Professor. In 1981, he was awarded a Postdoctoral Research Fellowship by the Irish Department of Education and spent one year at the University College Dublin, Dublin, Ireland, carrying out research in the area of microwave circuits. In 1982, he won a Postdoctoral Research Fellowship from the University of Queensland, where he worked on electromagnetic models for waveguide diode mounts. In 1984, he joined the Department of Electrical and Electronic Engineering, James Cook University, Townsville, Australia, as a Lecturer and then Senior Lecturer in the field of communications. 1988, he was a Visiting Senior Lecturer in the Department of Electronics and Computer Science, University of Southampton, U.K. In 1989, he joined the Department of Computer Science and Electrical Engineering at the University of Queensland, Brisbane, Australia. In 1994, he held an appointment as a Visiting Professor in the University of Victoria, Canada. In 1998-99, he held an appointment as a Visiting Professor at Nanyang Technological University, Singapore. In 2001, he was a Visiting Professor with the City University of Hong Kong. In 2003, he was a Visiting Professor with the National University of Singapore and with the Swiss Federal Institute of Technology (ETH) in Zurich. He returned to the National University of Singapore as a Visiting Professor in 2008.

His research interests included industrial and medical applications of microwaves, multiple-input multiple-output (MIMO) systems and ultra wideband antennas for wireless communications, phased array antennas for mobile cellular and satellite communications, low profile antennas for reception of satellite broadcast TV programs, electromagnetic modelling of wave guiding and radiating structures, and conventional and space-level power combiners for solid-state oscillators and amplifiers. His work in these areas led to the development of theories and working prototypes of single and dual six-port network analysers, microwave liquid level gauging systems, full EM and approximate scattering models for MIMO systems, working prototypes of wideband smart antennas, phased and switched beam array antennas for Mobilesat, radial line slot array antennas for receiving DBS TV programs, reflection and transmission type space-level power combiners. The results of his work appeared in over 600 refereed technical papers, several book chapters, one book, one patent, and several research reports.

]]> Tadeusz Wysocki et al. Impact of Channel Estimation Errors on Effectiveness of Eigenvector-Based Jamming for Physical Layer Security in Wireless Networks http://digitalcommons.unl.edu/computerelectronicfacpub/103 http://digitalcommons.unl.edu/computerelectronicfacpub/103 Mon, 15 Oct 2012 11:31:45 PDT In this paper, we present our study of an Eigenvector-based artificial noise-based jamming technique developed to provide increased wireless physical layer security in transmit-receive diversity systems and analyze the impact of channel estimation errors on system performance. Our simulation results showed that with knowledge of perfect channel state information, the technique provided secrecy capacity of approximately 7 bits/s/Hz for a normalized transmit power of 25 dB for a variety of transmit, receive, and eavesdropper configurations. We also describe a novel method to simulate generalized channel state information estimation errors. While other publications neglect the impact of these estimation errors, our simulations show that the secrecy capacity decreased rapidly as the channel estimation errors increased. For instance, at 25% error the secrecy capacity of the jamming technique was only slightly better than the non-jamming case. Our paper also outlines upcoming research efforts to further explore error sensitivity and channel state temporal stability through experimentation.

]]> James M. Taylor et al. Battery-aware Multimedia Coding Optimization by Dynamic Frequency Scaling http://digitalcommons.unl.edu/computerelectronicfacpub/102 http://digitalcommons.unl.edu/computerelectronicfacpub/102 Mon, 15 Oct 2012 11:27:22 PDT Nowadays, multimedia application and video streaming have gained a great popularity because of the boasting development on mobile hardware, and battery driven devices have emerged with a tremendous speed. Due to the important issue of battery efficiency on mobile devices, many optimization algorithms have being proposed toward various of battery powered platforms and scenarios. Most of the provided solutions choose to aim at the minimization of energy usage under a given task scheduling by adjusting parameters reside in the processes of different schemes. However, the battery discharging characteristics and its instant output pattern are still ignored if the optimization is done only from high level adjustment. In this paper, we propose a battery-aware optimization framework toward the H.264 video coding by applying dynamic frequency scaling on hardware platform. The CPU frequency can be dynamically adjusted according to the instant status of battery in order to maximize the number of the coding frame. Experimental results indicate the efficiency and effectiveness of the proposed optimization framework.

]]> Jianxin Sun et al. Mobile WiMAX Throughput and Delay Measurements in Railroad Environment http://digitalcommons.unl.edu/computerelectronicfacpub/101 http://digitalcommons.unl.edu/computerelectronicfacpub/101 Mon, 15 Oct 2012 11:25:55 PDT The railroad industry in North America is heavily involved in improving the broadband wireless connectivity of their railroad operations. We propose our approach of establishing a Mobile WiMAX test bed as a part of our collaborations with the Federal Railroad Administration (FRA) for investigating the performance of current and upcoming broadband wireless technologies in a railroad environment. The focus is on studying the impact of mobility on the wireless system throughput for moving trains at high velocities. Our goal is to provide a comprehensive measurement that will assist others in understanding Mobile WiMAX performance and guiding future network deployment. In this paper, we describe details of our test bed and discuss test results obtained from our laboratory and test bed. Based on our measurements, we can achieve a throughput of approximately 2.8 Mbps downlink and 2 Mbps uplink with the most robust modulation scheme, a maximum distance of 7.5 kilometers, and a speed of 60 mph, making Mobile WiMAX a promising candidate for large-scale deployments in environments such as the railroad industry.

]]> Puttipong Mahasukhon et al. A Study On Energy Efficient Multi-Tier Multi-Hop Wireless Sensor Networks For Freight-Train Monitoring http://digitalcommons.unl.edu/computerelectronicfacpub/100 http://digitalcommons.unl.edu/computerelectronicfacpub/100 Mon, 15 Oct 2012 11:24:33 PDT The North American freight railroad industry is trying to leverage wireless sensor networks (WSN) onboard railcars for advanced monitoring and alerting. In railroad environments, freight train WSNs exhibit a linear chain-like topology of significant length. Thus, existing wireless technologies such as the IEEE 802.15.4 communication protocol, based on a star topology, are unable to provide reliable service. The end-to-end communication between nodes generally relies on individual nodes communicating with their respective neighbors to carry the information over multiple hops and deliver it to the preferred destination. The routing performance and reliability significantly degrades with increasing number of hops. We proposed a multitier multi-hop network which is designed to overcome these issues in large-scale multi-hop WSNs in railroad environments. This approach has significant advantages, such as more data bandwidth, higher reliability, and lower energy consumption. Our analytical results show that the proposed multi-tier communication approach spends energy more efficiently and utilizes less resource than the traditional chain topology on board freight trains.

]]> Puttipong Mahasukhon et al. Power Controlled Coded-Sequence Self-Encoded Spread Spectrum Communications http://digitalcommons.unl.edu/computerelectronicfacpub/99 http://digitalcommons.unl.edu/computerelectronicfacpub/99 Mon, 15 Oct 2012 11:22:21 PDT In this paper, we propose to apply power control to coded-sequence self-encoded spread spectrum (CS-SESS) communications in dynamic fading channels. We determine the statistical characteristics of the power enhancement in the transmitter due to power control and show that the proposed approach improves the power efficiency in mobile cellular systems.

In addition, we propose to mitigate self interference in CSSESS by exploiting the information that the transmitter obtains, through feedback training sequences, about the de-spreading code in the receiver. The results show that the mitigation is significant even with only selective training chips from the de-spreading sequence. Similar improvement can be achieved with feed-forward training sequences to the receiver about the spreading code in the transmitter.

]]> Poomathi Duraisamy et al. Dynamic Video Object Detection with Single PTU Camera http://digitalcommons.unl.edu/computerelectronicfacpub/98 http://digitalcommons.unl.edu/computerelectronicfacpub/98 Mon, 08 Oct 2012 08:37:22 PDT This paper presents a video object detection method under dynamic background with single PTU (pantilt unit) camera. The overall procedure contains two steps. First the moving object is tracked through interactive Mean Shift estimation and PTU control. Camera angular speed is updated online according to the estimated object position, whereby the object can remain in the center area of the image plane. In the second step, the foreground is detected through background subtraction and shape contour. An adaptive correlation thresholding method is applied to mitigate the detection distortion in boundary areas. Variational level set contour is then applied to further remove noises and locate moving areas. Our contribution is to incorporate in this procedure the special property of camera movement on a PTU to realize automatic tracking and efficient background matching for motion detection. As demonstrated in the experiment, the proposed method well outlines the foreground objects.

]]> Yun Ye et al. A Novel Channel Probing/Scanning Scheme for Secure Fast Handoff in IEEE 802.11-based Wireless Networks http://digitalcommons.unl.edu/computerelectronicfacpub/97 http://digitalcommons.unl.edu/computerelectronicfacpub/97 Mon, 08 Oct 2012 08:29:13 PDT With the proliferation of wireless networks for practical deployments in recent years, secure fast handoff has become significantly important to provide secured access while reduce the latency caused by handoff procedure. Channel probing/scanning delay has been a major contribution to the overall latency of handoff in IEEE 802.11 based wireless networks. In this paper, we present a novel secure fast handoff scheme that adopts network-assisted radio statement (NACS) to eliminate lengthy probing/scanning delay by taking advantage of the knowledge of network topology of neighboring nodes in the network. We apply an opportunistic mechanism to retrieve the channel condition from neighboring nodes close enough to reduce the scanning/probing delay while providing secure wireless access for the handoff candidate node. In this manner, it can reduce the channel probing/scanning delay and achieve secure handoff. We show analysis and simulation results to verify the performance of the proposed secure fast handoff scheme.

]]> Ye Yan et al. Quantitative Analysis of Propagation Characteristics for Mobile WiMAX http://digitalcommons.unl.edu/computerelectronicfacpub/96 http://digitalcommons.unl.edu/computerelectronicfacpub/96 Mon, 08 Oct 2012 08:22:05 PDT In wireless networks, careful planning and link budget analysis is required for delivering maximum throughput reliably with minimum overhead. The efficiency of planning and eventual network performance is totally dependent upon the accuracy and quality of data used for analysis. In most studies, computer simulations and analytical models are used for generating such data. However these simulations are limited to many assumptions which are different from the actual implemented hardware, therefore, the data generated are not accurate. In this paper, we analyze the performance of Mobile WiMAX utilizing the empirical data measured from leading WiMAX equipment. We believe this data can be used to predict an accurate and reliable throughput and link budget in WiMAX networks.

]]> Pradhumna Shrestha et al. A Simple Upper Bound of the Gaussian 𝑄-Function with Closed-Form Error Bound http://digitalcommons.unl.edu/computerelectronicfacpub/95 http://digitalcommons.unl.edu/computerelectronicfacpub/95 Mon, 08 Oct 2012 08:13:49 PDT We present a simple upper bound of the Gaussian Q-function with its closed-form error bound. The proposed approximation can be applied to the evaluation of the average error probability of digital modulations with its error bound. Our bit error rate (BER) bound can be easily applied to fading channels.

]]> Won Mee Jang A Cross-Layer Parallel Handover Optimization Scheme for WiMAX Networks http://digitalcommons.unl.edu/computerelectronicfacpub/94 http://digitalcommons.unl.edu/computerelectronicfacpub/94 Thu, 04 Oct 2012 13:32:25 PDT The handover performance plays a crucial role in guaranteeing the quality of real-time applications in WiMAX networks. In general, a handover process can be divided into four stages: i) cell reselection, ii) handover preparation, iii) link layer handover, and iv) IP layer handover. A cross-layer parallel handover optimization (CPHO) scheme is proposed in this paper to reduce the handover signaling overhead and latency in each stage. The key idea of our proposed scheme is that uses the knowledge achieved from the backhaul inter-BS communications to reduce the HO control message load in wireless links and overlaps the executions of the link layer and the network layer handover process. Therefore the mean of the handover interruption time can be significantly reduced. The numerical analysis and simulation results show that the proposed approach significantly enhances the handover performance.

]]> Ting Zhou et al. Scalable Distributed Communication Architectures to Support Advanced Metering Infrastructure in Smart Grid http://digitalcommons.unl.edu/computerelectronicfacpub/93 http://digitalcommons.unl.edu/computerelectronicfacpub/93 Thu, 04 Oct 2012 13:30:45 PDT In this paper, we investigate the scalability of three communication architectures for advanced metering infrastructure (AMI) in smart grid. AMI in smart grid is a typical cyber-physical system (CPS) example, in which large amount of data from hundreds of thousands of smart meters are collected and processed through an AMI communication infrastructure. Scalability is one of the most important issues for the AMI deployment in smart grid. In this study, we introduce a new performance metric, accumulated bandwidth distance product (ABDP), to represent the total communication resource usages. For each distributed communication architecture, we formulate an optimization problem and obtain the solutions for minimizing the total cost of the system that considers both the ABDP and the deployment cost of the meter data management system (MDMS). The simulation results indicate the significant benefits of the distributed communication architectures over the traditional centralized one. More importantly, we analyze the scalability of the total cost of the communication system (including MDMS) with regard to the traffic load on the smart meters for both the centralized and the distributed communication architectures. Through the closed form expressions obtained in our analysis, we demonstrate that the total cost for the centralized architecture scales linearly as O(λN), with N being the number of smart meters, and λ being the average traffic rate on a smart meter. In contrast, the total cost for the fully distributed communication architecture is O(λ⅔N⅔), which is significantly lower.

]]> Jian Zhou et al. A Novel Adaptive Distributed Cooperative Relaying MAC Protocol for Vehicular Networks http://digitalcommons.unl.edu/computerelectronicfacpub/92 http://digitalcommons.unl.edu/computerelectronicfacpub/92 Thu, 04 Oct 2012 13:25:55 PDT Explosive growth in Information Technology has enabled many innovative application areas such as large-scale outdoor vehicular networks for vehicle-to-vehicle communications. By providing time-sensitive and location-aware information, vehicular networks can contribute to a safer and more efficient driving experience. However, the performance of vehicular networks requires robust and real-time data communications and is impacted by high mobility, intermittent connectivity, and unreliability of the wireless channel. In this paper, a novel adaptive distributed cooperative medium access control (ADCMAC) protocol is proposed in order to address the inherent problems in the IEEE 802.11 standard when employed in vehicular networks. ADC-MAC exploits spatial diversities to maximize the system throughput as well as the service range of vehicular networks. This is accomplished through adaptively selecting the most suitable helper and transmission mode for transmit/receive pairs among direct transmission (DT), cooperative relay (CR) transmission and two-hop relay (TR) transmission, in accordance with the channel quality and the positioning of relay nodes. Both our Markov Chain modeling based theoretical analysis and ns-2 simulation experiments show that our ADC-MAC protocol outperforms existing schemes under the same network scenarios and maximizes the achieved system throughput and service distance.

]]> Ting Zhou et al. Cross-layer Optimized Coding Mode Selection for Wireless Video Communications http://digitalcommons.unl.edu/computerelectronicfacpub/91 http://digitalcommons.unl.edu/computerelectronicfacpub/91 Thu, 04 Oct 2012 13:23:49 PDT This paper proposed a coding mode selection method for video transmission over wireless networks. Unlike previous mode selection methods disregarding channel distortion or assuming constant packet loss rate (PLR), this method includes a cross-layer controller to collect both source and channel information. The mode selection process is formulated as a delay constrained distortion minimization problem. The three components in the resulting Lagrange cost function, namely distortion, Lagrange multiplier and packet delay, are estimated with online channel information feedback. Suboptimal coding decision and physical layer modulation and coding scheme (MCS) are determined by the controller for each packet. In our experiment, three coding modes, intra, inter and down sampling, are tested under various channel conditions. Compared to conventional method, 3.6dB to 7.5dB average reduction in distortion is achieved under different channel condition, while down sampling further gains up to 2.2dB distortion reduction in low data rate transmission.

]]> Yun Ye et al. A Secure and Reliable In-network Collaborative Communication Scheme for Advanced Metering Infrastructure in Smart Grid http://digitalcommons.unl.edu/computerelectronicfacpub/90 http://digitalcommons.unl.edu/computerelectronicfacpub/90 Thu, 04 Oct 2012 13:22:42 PDT We consider various security vulnerabilities of deploying Advanced Metering Infrastructure (AMI) in smart grid, and explore the issues related to confidentiality for customer privacy and customer behavior as well as message authentication for meter reading and control messages. There are only a very few research work on AMI authentications, and no work exists on confidentiality for user privacy and user behavior, from the best of our knowledge. In this paper, we propose an in-network collaborative scheme to provide secure and reliable AMI communications in smart grid, with smart meters interconnected through a multihop wireless network. In this approach, an AMI system can provide trust services, data privacy and integrity by mutual authentications whenever a new smart meter initiates and joins the smart grid AMI network. Data integrity and confidentiality are fulfilled through message authentication and encryption services respectively using the corresponding keys established in the mutual authentications. A transmission scheme is proposed to facilitate the data collection and management message delivery between smart meters and a local collector for AMI communications. Simulation results show that the proposed method has a better end-to-end delay and packet losses comparing with a basic security method, and the proposed method can provide secure and reliable communications for AMI in smart grid systems.

]]> Yun Ye et al. A Secure Data Aggregation and Dispatch Scheme for Home Area Networks in Smart Grid http://digitalcommons.unl.edu/computerelectronicfacpub/89 http://digitalcommons.unl.edu/computerelectronicfacpub/89 Thu, 04 Oct 2012 13:21:30 PDT Cyber security for smart grid communication systems is one of the most critical requirements need to be assured before smart grid can be operationally ready for the market. Privacy is one of a very important security services. The customer information privacy in smart grid need to be protected. Smart grid data privacy encompasses confidentiality and anonymity of the information extracted from smart devices and metering transmission in a smart grid communication system. In this paper, we consider a home area network as a basic reading data aggregation and dispatch unit in smart grid systems, and we propose a secure in-network data aggregation and dispatch scheme to keep the confidentiality and anonymity for collecting power usage information of smart home devices to the household smart meter and for the reverse control message distribution procedure. More specifically, we introduce an orthogonal chip code to spread reading-data of different smart home devices into spread code, followed by a circuit shifting operation to coupling neighboring smart devices tightly. We adopt an in-network mechanism to further mask it with the spread data and its forwarding data. Finally, we analyze the cyber security protection levels using an information theoretic quantity - residual uncertainty. Simulation studies are conducted to test the performance on different metering data sets for the proposed scheme. This paper sets the ground for further research on optimizing of home power management systems with regarding to the privacy of customer power usage behaviors.

]]> Yun Ye et al.