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University of Nebraska - Lincoln
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
- Keyword
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- Space Time Spreading (5)
- UWB (5)
- Vehicular Networks (4)
- Cooperative Relaying (3)
- Inter-symbol interference (3)
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- Pre-rake equalization (3)
- Time-reversed (3)
- Advanced metering infrastructure (AMI) (2)
- Amplify-and-forward (2)
- BER (2)
- Channel coding (2)
- Cognitive radio (CR) (2)
- Cross Layer (2)
- Delta function (2)
- Interleaving (2)
- MIMO (2)
- MRC (2)
- Mobile (2)
- Multi-user interference (2)
- Multi-user system (2)
- Multimedia (2)
- Multipath (2)
- Multirate (2)
- Protocol Optimization (2)
- QoS (2)
- Sampling (2)
- Secrecy capacity (2)
- Security (2)
- Smart grid (2)
- Spread spectrum (2)
Articles 91 - 107 of 107
Full-Text Articles in Computer Engineering
Modified Convolutional Interleavers And Their Performance In Turbo Codes, Sina Vafi, Tadeusz Wysocki
Modified Convolutional Interleavers And Their Performance In Turbo Codes, Sina Vafi, Tadeusz Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In previous work,we have presented application of a model of the convolutional interleaver in turbo codes acting as a block interleaver through inserting a number of stuff bits equal to the number of interleaver memories at the end of each data 6lock.h order to get better turbo codes performance, the interleaver with larger period, which increases the number of stuff bits and educes effective channel bandwidth usage, has been suggested. In this paper, we introduce a modification to this interleaver improving turbo codes performance without increasing the interleaver period. This is carried out by increasing distance of adjacent bits that …
Orthogonal Spreading Sequences Constructed Using Hall’S Difference Set, Jennifer Seberry, Le Chung Tran, Yejing Wang, Beata J. Wysocki, Tadeusz Wysocki, Ying Zhao
Orthogonal Spreading Sequences Constructed Using Hall’S Difference Set, Jennifer Seberry, Le Chung Tran, Yejing Wang, Beata J. Wysocki, Tadeusz Wysocki, Ying Zhao
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In the paper we propose a new set of orthogonal spreading sequences based on the Hadamard matrix of order 32 constructed using the Hall difference set. The proposed sequences are characterised by low peaks in the aperiodic cross-correlation functions and have also good aperiodic auto-correlation properties.
Complex Orthogonal Sequences From Amicable Hadamard Matrices, L. C. Tran, J. Seberry, B. J. Wysocki, Tadeusz Wysocki, T. Xia, Ying Zhao
Complex Orthogonal Sequences From Amicable Hadamard Matrices, L. C. Tran, J. Seberry, B. J. Wysocki, Tadeusz Wysocki, T. Xia, Ying Zhao
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
The paper deals with the novel technique of designing complex spreading sequences with only four phases (0.25π, 0.75π, 1.25π, 1.75π). The interesting feature of those new sequences is the fact that not only the complex sequences are orthogonal but the real parts and imaginary parts are independently orthogonal. This can be utilized for spreading of complex constellation signals where the independent spreading using bipolar sequences (real part for in-phase component and imaginary part for quadrature component) can be applied. The paper introduces the theoretical background, and some example constructions of the amicable …
A Performance Study Of Dynamic Zone Topology Routing Protocol, Mehran Abolhasan, Tadeusz A. Wysocki
A Performance Study Of Dynamic Zone Topology Routing Protocol, Mehran Abolhasan, Tadeusz A. Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In this paper we present a simulation study of a hybrid routing protocol we proposed in our previous work. Our hybrid routing strategy is called Dynamic Zone Topology Routing protocol (DZTR). This protocol has been designed to provide scalable routing in a Mobile Ad hoc Networking (MANET) environment. DZTR breaks the network into a number of zones by using a GPS. The topology of each zone is maintained proactively and the route to the nodes in other zones are determined reactively. DZTR proposes a number of different strategies to reduce routing overhead in large networks and reduce the single point …
Antenna Selection Scheme For Wireless Channels Utilizing Differential Space-Time Modulation, Le Chung Tran, Tadeusz A. Wysocki
Antenna Selection Scheme For Wireless Channels Utilizing Differential Space-Time Modulation, Le Chung Tran, Tadeusz A. Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In this paper, the authors prove that the differential space-time modulation techniques proposed in literature provide a full spatial diversity. Based on that, the authors propose an antenna selection scheme called general N-out-of-M antenna selection technique for wireless communications channels utilizing differential space-time modulation. The simulation shows that differential detection associated with our proposed technique provides much better bit error performance over that without antenna selection, and even over coherent detection without antenna selection at certain signal-to-noise ratios.
Convolutional Interleaver For Unequal Error Protection Of Turbo Codes, Sina Vafi, Tadeusz A. Wysocki, Ian Burnett
Convolutional Interleaver For Unequal Error Protection Of Turbo Codes, Sina Vafi, Tadeusz A. Wysocki, Ian Burnett
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
This paper describes construction of a convolutional interleaver as a block interleaver and discusses its application to turbo codes with equal and unequal error protection techniques. Based on simulations, different convolutional interleaver structures suitable for turbo codes with unequal error protection capability are suggested. Finally, based on conducted simulations the best method is selected.
Displacement Based Route Update Strategies For Proactive Routing Protocols In Mobile Ad Hoc Networks, Mehran Abolhasan, Tadeusz Wysocki
Displacement Based Route Update Strategies For Proactive Routing Protocols In Mobile Ad Hoc Networks, Mehran Abolhasan, Tadeusz Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
This paper presents a new route update strategy for performing proactive route discovery in Mobile Ad hoc Networks (MANETs). In this strategy, the rate at which route updates are sent into the network is controlled by how often a node changes its location by a required distance. We refer to this updating strategy as Minimum Displacement Update Routing (MDUR). We implemented MDUR on top of the Fisheye State Routing (FSR) protocol and investigated its performance by simulation. The simulations where performed in a number of different scenarios, with varied network mobility, density, traffic and boundary. Our results indicate that MDUR …
Increasing Performance Of Sqrd Decoding For Lst Systems, Phillip Conder, Tadeusz A. Wysocki
Increasing Performance Of Sqrd Decoding For Lst Systems, Phillip Conder, Tadeusz A. Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
A number of decoding schemes have been proposed for Layered Space-Time systems, such as the Ordered Successive Interference Cancellation and the Sorted QR Decomposition. We describe here a new addition to that group, increasing the performance of Layered Space-Time decoding by using the Sorted QR Decomposition technique to construct a list of constellations to be passed to a Maximum Likelihood decoder. This paper shows that signifcant performance improvement can be obtained for symmetric systems, where there is an equal number of transmit and receive antennas. It shows that the proposed scheme, has a roughly linear increase in complexity compared to …
On The Effect Of Adjacent Sector Multiple Access Interference On Space Time Spreading Systems, Peter Vial, Ibrahim Raad, Tadeusz A. Wysocki
On The Effect Of Adjacent Sector Multiple Access Interference On Space Time Spreading Systems, Peter Vial, Ibrahim Raad, Tadeusz A. Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
Space Time Spreading systems are proposed as a method to enhance communications between the Base Station (BS) and Mobile Station (MS) by using multiple transmit antennas at the Base Station. This provides a form of transmit diversity when there are more than one transmitting antennas. Space Time Spreading systems have been shown to be efficient in their use of the limited number of orthogonal spreading sequences and to provide a diversity gain, which in the case of two transmitter antennas at the BS and one receiving antenna at the MS, is of order two. The paper looks at the effect …
Combinatorial Constructions Of 3- And 4-Secure Codes, Yeijing Wang, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki, Willy Susilo, Tianbing Xia, Ying Zhao, Le Chung Tran
Combinatorial Constructions Of 3- And 4-Secure Codes, Yeijing Wang, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki, Willy Susilo, Tianbing Xia, Ying Zhao, Le Chung Tran
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In this paper, 3- and 4-secure codes are constructed from combinatorial designs. Both constant weight and non-constant weight codes are shown.
Optimization Of Orthogonal Polyphase Spreading Sequences For Wireless Data Applications, B. J. Wysocki, Tadeusz Wysocki
Optimization Of Orthogonal Polyphase Spreading Sequences For Wireless Data Applications, B. J. Wysocki, Tadeusz Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In this paper, we propose a simple but efficient method for optimizing correlation properties of polyphase spreading sequences for asynchronous DS CDMA applications. The proposed method can be used to minimize the mean square value of aperiodic crosscorrelation or the mean square value of aperiodic autocorrelation, the maximum value of aperiodic crosscorrelation functions, merit factor or other properties of the sequence set. The important feature of the method is that when applied to orthogonal sequences, it modifies correlation properties of the sequence set, while preserves their orthogonality for perfect synchronization.
Low Coherence Fiber Optics For Random Noise Radar, Ruixiang Jiang, Kyle W. Wolfe, Lim Nguyen
Low Coherence Fiber Optics For Random Noise Radar, Ruixiang Jiang, Kyle W. Wolfe, Lim Nguyen
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
Coherent random noise radar has been developed at the University of Nebraska for the detection and identification of shallow subsurface objects such as land mines. Other application ranges from remote sensing, synthetic aperture radar and high-resolution interferometer, to covert target tracking. in this paper, we describe the experimental investigation of a novel applicntion of superfluorescent fiber or erbium doped fiber amplifier (EDFA) light sources(SFS) for random noise radar. The ultra-wide band noise coupled with the use of optical fiber delay lines makes SFS ideally suited for random noise radar applications. Optical fiber- makes long and multiple-step delay lines of a …
Ds Cdma Scheme For Watm With Errors And Erasures Decoding, Beata J. Wysocki, Hans-Jürgen Zepernick, Tadeusz Wysocki
Ds Cdma Scheme For Watm With Errors And Erasures Decoding, Beata J. Wysocki, Hans-Jürgen Zepernick, Tadeusz Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In the paper, we present simulation results for the 13 channel DS CDMA WATM LAN utilising optimized complex spreading signatures based on Walsh functions. The method to obtain those optimized spreading signatures, as well as the full set of the coefficients giving the minimum level of cross-correlation between any pair of the channels is shown. The resultant system BER as well as the distribution of errors within WATM cells is given. The obtained results indicate that with the application of a hybrid ARQ scheme with errors and erasures decoding, the number of WATM cells which would require retransmission is in …
Ds Cdma Scheme For Watm Lan With Error Control, Beata J. Wysocki, Tadeusz A. Wysocki, Hans J. Zepernick
Ds Cdma Scheme For Watm Lan With Error Control, Beata J. Wysocki, Tadeusz A. Wysocki, Hans J. Zepernick
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In the paper, we present simulation results for the 13 channel DS CDMA WATM LAN utilising optimized complex spreading signatures based on Walsh- Rademacber functions. The method to obtain those optimized spreading signatures, as well as the full set of the coefficients giving the minimum level of crosscorrelation between any pair of the channels is shown. The resultant system BER as well as the distribution of errors within WATM cells is given. The obtained results indicate that with the application of a hybrid ARQ scheme, capable of correcting 10 errors, the number of WATM cells which would require retransmission is …
Error Performance Of The 13-Channel Ds Cdma Watm Lan, Beata J. Wysocki, Tadeusz Wysocki, Hans J. Zepernick
Error Performance Of The 13-Channel Ds Cdma Watm Lan, Beata J. Wysocki, Tadeusz Wysocki, Hans J. Zepernick
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
In the paper, we present simulation results for the 13 channel DS CDMA WATM LAN utilising optimized complex spreading signatures based on Walsh-Rademacher functions. The method to obtain those optimized spreading signatures, as well as the full set of the coefficients giving the minimum level of cross-correlation between any pair of the channels is shown. The resultant system BER and the distribution of errors within encapsulated WATM cells is given. The obtained results indicate that with the application of a hybrid ARQ scheme, capable of correcting 10 errors, the number of WATM cells which would require retransmission is in the …
A Method To Partially Suppress Is1 And Ma1 For Ds Ss Cdma Wireless Networks, Beata J. Wysocki, Tadeusz A. Wysocki
A Method To Partially Suppress Is1 And Ma1 For Ds Ss Cdma Wireless Networks, Beata J. Wysocki, Tadeusz A. Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
We propose a method to partially suppress ISI and MAI for US SS CDMA schemes in wireless LANs. The method can be regarded as an alternative approach to combat ISI and in particular MAI by the use of advanced multiuser detection. Instead of using very sophisticated detectors, we propose introduction of a simple modification to the carrier waveform which results in very substaiitial reduction in cross-correlation belween users and an off-peak auto-correlation. The method can be applied to any DS SS CDMA scheme, but should be particularly useful in the case of short spreading signatures, as is the case of …
Power Spectra Of Signal Formats For Ds-Ss Cdma Wireless Lans, Beata J. Wysocki, Tadeusz Wysocki
Power Spectra Of Signal Formats For Ds-Ss Cdma Wireless Lans, Beata J. Wysocki, Tadeusz Wysocki
Department of Electrical and Computer Engineering: Faculty Publications (to 2015)
The paper deals with the spectral analysis of signal formats for DS-SS CDMA WLANs. The main emphasis is put on introduction of a quantitative measure which allows for comparison of different spreading codes and channel modulations from the viewpoint of a uniformity of an in-hand power distribution Such a measure is essential to compare different DS-SS CDMA systems performance in mitigating the effects of frequency selective fading.