Vehicular Ad Hoc Networks (VANETs) are increasingly playing a fundamental role in improving drivi... more Vehicular Ad Hoc Networks (VANETs) are increasingly playing a fundamental role in improving driving safety. However, VANETs in a sparse environment may add risk to driving safety. The probability of a low density of vehicles in a rural area at midnight is very high. Consequently, the packet will be lost due to the lack of other vehicles, and the arrival of the following vehicles in the accident area is unavoidable. To overcome this problem, VANET is integrated with Wireless Sensor Network (WSN). The most challenging features of VANETs are their high mobility. This high mobility causes sensor nodes to consume most of their energy during communication with other nodes, leading to frequent network disconnectivity. With the evolution of VANET and WSN, the Store/Carry-Forward (SCF) paradigm has emerged as an exciting research area in the Delay Tolerant Networks (DTNs) to solve network disconnectivity. This paper proposes the Energy-Mobility-Connectivity aware routing protocol (EMCR) for ...
Evolving global navigation satellite system (GNSS) threats are becoming a concern for all unmanne... more Evolving global navigation satellite system (GNSS) threats are becoming a concern for all unmanned aerial systems (UAS) dependent upon GNSS aided navigation. More and more UAS platforms are considering integration of GNSS anti-jam (AJ) electronics and controlled radiation pattern antenna (CRPA) arrays to mitigate threats and ensure mission success. Due to restrictions and excessive costs for live-sky range testing, evaluation of these AJ systems requires specialized lab equipment and software to replicate the threats in dynamic environments. A test capability has been developed and validated, providing the test community with a cost-effective approach for evaluating AJ systems [1]. The test capability, referred to as the wavefront integrated threat simulator (WITS), utilizes a core architecture with mechanical tap-delay lines [2] and flexible personal computer interface options. Its expandability provides a range of simulated radio frequency (RF) antenna-element channels and capabilities with variable cost. The chief contribution of this paper lies in its calibration procedure which has been developed to minimize the aggregate angle of arrival (AoA) error for the GPS L1 frequency and the analytical analysis of the AoA error region. The WITS can be configured for a simple test configuration using a 4-channel system for $11,000 and may be expanded up to an N-channel configuration with high fidelity signal representation (i.e., Doppler, macro RF-path simulation with micro per-element calibrated delay ranges). The WITS validation includes per-channel calibration tables, per-channel theoretical phase contribution to angle-of-arrival (AoA) versus time, system level AoA error region analysis, AoA Multiple Signal Classification (MUSIC) estimate validation, output power requirements (potentially >120 dB Jamming to Signal ratio), and overall system latency. The modular design allows for user selection of appropriate fidelity and ensures a successful integration and evaluation of a GPS AJ system on multiple platforms and HWIL environments.
The engineering community is confident in its assessment of how an angle tracker will perform in ... more The engineering community is confident in its assessment of how an angle tracker will perform in a multitarget environment as the target-to-tracker range decreases, causing targets to leave the tracker antenna beam. When one target signal dominates due to the angular separation of the targets, the tracker will center on the dominating signal. It is not well understood how the tracker will behave when angle separation is not the limiting factor in signal strength. That topic is addressed in this paper. Specifically, we show how angle error signal normalization impacts track loop dynamics in a dual target scenario. If the error signal is normalized by an Automatic Gain Control (AGC), the behavior will depend upon the Doppler frequency separation of the two targets relative to the AGC bandwidth. The problem is addressed from a theoretical perspective, and via simulation. The theoretical and simulation results agree well.
2018 IEEE/ION Position, Location and Navigation Symposium (PLANS), 2018
Some of the biggest investments surrounding Global Navigation Satellite System (GNSS) receivers a... more Some of the biggest investments surrounding Global Navigation Satellite System (GNSS) receivers are the development and integration of adaptive nulling technology. Researchers, developers, and integrators need to understand the effects these nulling technologies have on the navigation receivers and systems using the modified RF output, and their ability to suppress undesired signals. Due to the sensitive nature of the GNSS spectrum, outdoor testing of Anti-Jam (AJ) electronics and Controlled Reception Pattern Antenna (CRPA) technologies are difficult, expensive, and often cause schedule delay. It is becoming more important to develop cost effective means to evaluate adaptive nulling advancements and their effects on the receivers with which they are being integrated. Aside from open air testing, this evaluation and integration is best accomplished through modeling and simulation techniques. This paper investigates a method of using a Steiner tree model to relate the per-element phase errors of a simulated wavefront and their effect at the system level. Theory developed [1] to expand the possible angle of arrival (AoA) simulation options through a series of untraditional tap selections will be implemented in a series of digital and hardware simulations.
Heterogeneous cellular networks (HetNets), consisting of macrocells overlaid with small cells, ha... more Heterogeneous cellular networks (HetNets), consisting of macrocells overlaid with small cells, have become an integral part of existing cellular wireless networks to satisfy an ever increasing demand for mobile broadband applications and services. In this paper, the coverage probability in a downlink HetNet, comprising of multi-tier MIMO Base Stations (BSs) serving multiple users, assuming Rician-Rayleigh fading has been evaluated. Also, comparison of the Area Spectral Efficiency (ASE) for multi-user (MU) MIMO with the single-input single-output (SISO) case, demonstrates the gain in performance MIMO techniques can provide. Through simulation it has been demonstrated that as the number of users increase, the inter-stream interference increases, resulting in a reduction of coverage probability.
In this paper, the performance of the Z-MAP algorithmis explored in the context of the turbo equa... more In this paper, the performance of the Z-MAP algorithmis explored in the context of the turbo equalization of thefaster-than-Nyquist (FTN) signals. The complexity of the Z-MAP,in terms of the number of the surviving states at each time epoch,is studied. Finally, the performance of the Z-MAP is comparedto that of the backup M-BCJR for turbo equalizing the FTNsignals.
2020 27th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 2020
We show the development of a wideband delay guided by the closed-form, analytic solution of a sol... more We show the development of a wideband delay guided by the closed-form, analytic solution of a solvable chaotic oscillator. This delay serves as a crucial component in the design of a matched filter receiver that optimally detects chaotic waveforms in the presence of noise. Unlike most chaotic systems, a special class of solvable chaos permits a closed-form analytic expression that may be used to guide designs. Specifically, we employ a cascade of 7th-order Bessel filter cells to accommodate various bandwidths associated with these oscillators. These bandwidth increments are guided by a closed form expression of the chaotic signals' spectral content. The resulting delay has wideband frequency characteristics while keeping group delay maximally flat within the operating band. Next, we analyze our results through time series comparison of the delayed signals with corresponding, analytically reconstructed chaotic waveforms. Finally, we summarize the trade-off space for these delay d...
Scheduled dataflow architecture (SDF) executes instructions in the prescribed order in which they... more Scheduled dataflow architecture (SDF) executes instructions in the prescribed order in which they arrive, even though data might already be available for executing the instructions. In this paper, we model the SDF using an open queuing network with feedback. Two models are proposed. The first model is comprised of a network of single queues each with a dedicated processor (server), while the second model is comprised of multiple servers for a single queue. A simulation is performed using mean value analysis on the network of queues. The average response time is computed for different numbers of synchronization and execution units in the processor. The paper also provides a comparison between the utilization of the queuing model with multiple servers and the queuing model with a single server. The two models depict the scheduling of instructions in the dataflow architecture in an efficient manner.
Using two transmit antennas and one receive antenna, Alamouti's schemes (1998) provide the ma... more Using two transmit antennas and one receive antenna, Alamouti's schemes (1998) provide the maximum possible diversity gain with a maximum likelihood detector. In addition to diversity gain, this paper maximizes the coding gain using the minimum of the determinants of the code difference matrices. In order to achieve the maximum coding gain on a Rayleigh fading channel, a trellis code
2011 Eighth International Conference on Information Technology: New Generations, 2011
ABSTRACT An automatic feedback control system that maintains an average bit error rate (BER) on d... more ABSTRACT An automatic feedback control system that maintains an average bit error rate (BER) on decoded code words is proposed for log-likelihood ratio (LLR)error correction code (ECC) decoders. The input to the controller is the LLR output of the decoder, while the controller output is the decoder iteration parameter. The loop error signal is constructed by computing the difference between the scaled decoder LLR of codeword estimates and an ideal LLR value derived from a target BER. The discrete time transfer function of a proposed proportional-integral (PI) loop filter with integrator feedback using ideal linear analysis is presented, followed by loop simulation results using the decoder.
International Journal of Pure and Applied Mathematics
A closed queuing network model with single servers has been proposed to model dataflow in distrib... more A closed queuing network model with single servers has been proposed to model dataflow in distributed diagnostic-processing systems. Multi-threading is useful in reducing the latency by switching among a set of threads in order to improve the processor utilization. Two sets of processors, synchronization and execution processors exist. Synchronization processors handle load/store operations and execution processors handle arithmetic/logic and control operations. A closed queuing network model is suitable for a large number of job arrivals. The normalization constant is derived using a recursive algorithm for the given model. Performance measures such as average response times and average system throughput are derived and plotted against the total number of processors in the closed queuing network model. Other important performance measures like processor utilizations, average queue lengths, average waiting times and relative utilizations are also derived.
In wideband code division multiple access (W-CDMA) sys-tems, inter-symbol interference (ISI) intr... more In wideband code division multiple access (W-CDMA) sys-tems, inter-symbol interference (ISI) introduced by multipath propaga-tion can be significant due to large multipath delays. In the presence of multipath, each signal is subjected to frequency-selective fading and the orthogonality condition is distorted due to increased cross-correlation between the signature waveforms of the different users. In this paper, we study a subspace-based signature waveform estimation for downlink W-CDMA systems that provides estimates of the multiuser channels by exploiting the second-order statistics of the transmitted signal at the base station. We employ multiple antennas at the receiver to estimate the signature waveforms for overloaded systems. A zero-forcing equal-izer and a matched-filter detector are employed to estimate the received signal constellations. Simulations are performed to evaluate the effec-tiveness of the algorithm.
A series expression for evaluating the channel capacity of the binary input AWGN channel is devel... more A series expression for evaluating the channel capacity of the binary input AWGN channel is developed which precludes the necessity of numerical integration. This series expression is compact and easy to evaluate. In addition, tight upper and lower bounds are developed for the binary input AWGN channel capacity. These bounds also provide good approximations for the capacity and are within 0·1% relative error (within 0.01% for upper bound) for C≥0·457 and a corresponding E b /N 0 ≥0dB.
Vehicular Ad Hoc Networks (VANETs) are increasingly playing a fundamental role in improving drivi... more Vehicular Ad Hoc Networks (VANETs) are increasingly playing a fundamental role in improving driving safety. However, VANETs in a sparse environment may add risk to driving safety. The probability of a low density of vehicles in a rural area at midnight is very high. Consequently, the packet will be lost due to the lack of other vehicles, and the arrival of the following vehicles in the accident area is unavoidable. To overcome this problem, VANET is integrated with Wireless Sensor Network (WSN). The most challenging features of VANETs are their high mobility. This high mobility causes sensor nodes to consume most of their energy during communication with other nodes, leading to frequent network disconnectivity. With the evolution of VANET and WSN, the Store/Carry-Forward (SCF) paradigm has emerged as an exciting research area in the Delay Tolerant Networks (DTNs) to solve network disconnectivity. This paper proposes the Energy-Mobility-Connectivity aware routing protocol (EMCR) for ...
Evolving global navigation satellite system (GNSS) threats are becoming a concern for all unmanne... more Evolving global navigation satellite system (GNSS) threats are becoming a concern for all unmanned aerial systems (UAS) dependent upon GNSS aided navigation. More and more UAS platforms are considering integration of GNSS anti-jam (AJ) electronics and controlled radiation pattern antenna (CRPA) arrays to mitigate threats and ensure mission success. Due to restrictions and excessive costs for live-sky range testing, evaluation of these AJ systems requires specialized lab equipment and software to replicate the threats in dynamic environments. A test capability has been developed and validated, providing the test community with a cost-effective approach for evaluating AJ systems [1]. The test capability, referred to as the wavefront integrated threat simulator (WITS), utilizes a core architecture with mechanical tap-delay lines [2] and flexible personal computer interface options. Its expandability provides a range of simulated radio frequency (RF) antenna-element channels and capabilities with variable cost. The chief contribution of this paper lies in its calibration procedure which has been developed to minimize the aggregate angle of arrival (AoA) error for the GPS L1 frequency and the analytical analysis of the AoA error region. The WITS can be configured for a simple test configuration using a 4-channel system for $11,000 and may be expanded up to an N-channel configuration with high fidelity signal representation (i.e., Doppler, macro RF-path simulation with micro per-element calibrated delay ranges). The WITS validation includes per-channel calibration tables, per-channel theoretical phase contribution to angle-of-arrival (AoA) versus time, system level AoA error region analysis, AoA Multiple Signal Classification (MUSIC) estimate validation, output power requirements (potentially >120 dB Jamming to Signal ratio), and overall system latency. The modular design allows for user selection of appropriate fidelity and ensures a successful integration and evaluation of a GPS AJ system on multiple platforms and HWIL environments.
The engineering community is confident in its assessment of how an angle tracker will perform in ... more The engineering community is confident in its assessment of how an angle tracker will perform in a multitarget environment as the target-to-tracker range decreases, causing targets to leave the tracker antenna beam. When one target signal dominates due to the angular separation of the targets, the tracker will center on the dominating signal. It is not well understood how the tracker will behave when angle separation is not the limiting factor in signal strength. That topic is addressed in this paper. Specifically, we show how angle error signal normalization impacts track loop dynamics in a dual target scenario. If the error signal is normalized by an Automatic Gain Control (AGC), the behavior will depend upon the Doppler frequency separation of the two targets relative to the AGC bandwidth. The problem is addressed from a theoretical perspective, and via simulation. The theoretical and simulation results agree well.
2018 IEEE/ION Position, Location and Navigation Symposium (PLANS), 2018
Some of the biggest investments surrounding Global Navigation Satellite System (GNSS) receivers a... more Some of the biggest investments surrounding Global Navigation Satellite System (GNSS) receivers are the development and integration of adaptive nulling technology. Researchers, developers, and integrators need to understand the effects these nulling technologies have on the navigation receivers and systems using the modified RF output, and their ability to suppress undesired signals. Due to the sensitive nature of the GNSS spectrum, outdoor testing of Anti-Jam (AJ) electronics and Controlled Reception Pattern Antenna (CRPA) technologies are difficult, expensive, and often cause schedule delay. It is becoming more important to develop cost effective means to evaluate adaptive nulling advancements and their effects on the receivers with which they are being integrated. Aside from open air testing, this evaluation and integration is best accomplished through modeling and simulation techniques. This paper investigates a method of using a Steiner tree model to relate the per-element phase errors of a simulated wavefront and their effect at the system level. Theory developed [1] to expand the possible angle of arrival (AoA) simulation options through a series of untraditional tap selections will be implemented in a series of digital and hardware simulations.
Heterogeneous cellular networks (HetNets), consisting of macrocells overlaid with small cells, ha... more Heterogeneous cellular networks (HetNets), consisting of macrocells overlaid with small cells, have become an integral part of existing cellular wireless networks to satisfy an ever increasing demand for mobile broadband applications and services. In this paper, the coverage probability in a downlink HetNet, comprising of multi-tier MIMO Base Stations (BSs) serving multiple users, assuming Rician-Rayleigh fading has been evaluated. Also, comparison of the Area Spectral Efficiency (ASE) for multi-user (MU) MIMO with the single-input single-output (SISO) case, demonstrates the gain in performance MIMO techniques can provide. Through simulation it has been demonstrated that as the number of users increase, the inter-stream interference increases, resulting in a reduction of coverage probability.
In this paper, the performance of the Z-MAP algorithmis explored in the context of the turbo equa... more In this paper, the performance of the Z-MAP algorithmis explored in the context of the turbo equalization of thefaster-than-Nyquist (FTN) signals. The complexity of the Z-MAP,in terms of the number of the surviving states at each time epoch,is studied. Finally, the performance of the Z-MAP is comparedto that of the backup M-BCJR for turbo equalizing the FTNsignals.
2020 27th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 2020
We show the development of a wideband delay guided by the closed-form, analytic solution of a sol... more We show the development of a wideband delay guided by the closed-form, analytic solution of a solvable chaotic oscillator. This delay serves as a crucial component in the design of a matched filter receiver that optimally detects chaotic waveforms in the presence of noise. Unlike most chaotic systems, a special class of solvable chaos permits a closed-form analytic expression that may be used to guide designs. Specifically, we employ a cascade of 7th-order Bessel filter cells to accommodate various bandwidths associated with these oscillators. These bandwidth increments are guided by a closed form expression of the chaotic signals' spectral content. The resulting delay has wideband frequency characteristics while keeping group delay maximally flat within the operating band. Next, we analyze our results through time series comparison of the delayed signals with corresponding, analytically reconstructed chaotic waveforms. Finally, we summarize the trade-off space for these delay d...
Scheduled dataflow architecture (SDF) executes instructions in the prescribed order in which they... more Scheduled dataflow architecture (SDF) executes instructions in the prescribed order in which they arrive, even though data might already be available for executing the instructions. In this paper, we model the SDF using an open queuing network with feedback. Two models are proposed. The first model is comprised of a network of single queues each with a dedicated processor (server), while the second model is comprised of multiple servers for a single queue. A simulation is performed using mean value analysis on the network of queues. The average response time is computed for different numbers of synchronization and execution units in the processor. The paper also provides a comparison between the utilization of the queuing model with multiple servers and the queuing model with a single server. The two models depict the scheduling of instructions in the dataflow architecture in an efficient manner.
Using two transmit antennas and one receive antenna, Alamouti's schemes (1998) provide the ma... more Using two transmit antennas and one receive antenna, Alamouti's schemes (1998) provide the maximum possible diversity gain with a maximum likelihood detector. In addition to diversity gain, this paper maximizes the coding gain using the minimum of the determinants of the code difference matrices. In order to achieve the maximum coding gain on a Rayleigh fading channel, a trellis code
2011 Eighth International Conference on Information Technology: New Generations, 2011
ABSTRACT An automatic feedback control system that maintains an average bit error rate (BER) on d... more ABSTRACT An automatic feedback control system that maintains an average bit error rate (BER) on decoded code words is proposed for log-likelihood ratio (LLR)error correction code (ECC) decoders. The input to the controller is the LLR output of the decoder, while the controller output is the decoder iteration parameter. The loop error signal is constructed by computing the difference between the scaled decoder LLR of codeword estimates and an ideal LLR value derived from a target BER. The discrete time transfer function of a proposed proportional-integral (PI) loop filter with integrator feedback using ideal linear analysis is presented, followed by loop simulation results using the decoder.
International Journal of Pure and Applied Mathematics
A closed queuing network model with single servers has been proposed to model dataflow in distrib... more A closed queuing network model with single servers has been proposed to model dataflow in distributed diagnostic-processing systems. Multi-threading is useful in reducing the latency by switching among a set of threads in order to improve the processor utilization. Two sets of processors, synchronization and execution processors exist. Synchronization processors handle load/store operations and execution processors handle arithmetic/logic and control operations. A closed queuing network model is suitable for a large number of job arrivals. The normalization constant is derived using a recursive algorithm for the given model. Performance measures such as average response times and average system throughput are derived and plotted against the total number of processors in the closed queuing network model. Other important performance measures like processor utilizations, average queue lengths, average waiting times and relative utilizations are also derived.
In wideband code division multiple access (W-CDMA) sys-tems, inter-symbol interference (ISI) intr... more In wideband code division multiple access (W-CDMA) sys-tems, inter-symbol interference (ISI) introduced by multipath propaga-tion can be significant due to large multipath delays. In the presence of multipath, each signal is subjected to frequency-selective fading and the orthogonality condition is distorted due to increased cross-correlation between the signature waveforms of the different users. In this paper, we study a subspace-based signature waveform estimation for downlink W-CDMA systems that provides estimates of the multiuser channels by exploiting the second-order statistics of the transmitted signal at the base station. We employ multiple antennas at the receiver to estimate the signature waveforms for overloaded systems. A zero-forcing equal-izer and a matched-filter detector are employed to estimate the received signal constellations. Simulations are performed to evaluate the effec-tiveness of the algorithm.
A series expression for evaluating the channel capacity of the binary input AWGN channel is devel... more A series expression for evaluating the channel capacity of the binary input AWGN channel is developed which precludes the necessity of numerical integration. This series expression is compact and easy to evaluate. In addition, tight upper and lower bounds are developed for the binary input AWGN channel capacity. These bounds also provide good approximations for the capacity and are within 0·1% relative error (within 0.01% for upper bound) for C≥0·457 and a corresponding E b /N 0 ≥0dB.
Uploads
Papers by Laurie Joiner