Spectrum utility efficiency is key in designing systems that can meet the heavier demands of band... more Spectrum utility efficiency is key in designing systems that can meet the heavier demands of bandwidth and data rate of future communication technologies. Shared spectrum techniques and collaborative protocols have thus been studied to better utilize already existing spectrum resources. In this paper, we present a spectrum trading approach that allows the licensed user's (LU) resources to be efficiently shared with the secondary user (SU) network in exchange for a monetary cost. The model is based on demand and supply economics, wherein the highest bidder for spectrum resource is awarded with transmission rights over licensed spectrum. The transmission opportunities for the SU consider every state of the licensed link, in the form of dynamic spectrum access (DSA), spectrum sharing, and relaying, each of which has an optimized cost that will maximize the returns for the LU. The numerical results backed by the analytical study show that this spectrum trading scheme allows for significant improvements in data rate and spectrum transmission opportunities than previous work conducted in either DSA or the spectrum sharing fields.
Military communication relies on robust and secure physical links that adhere to regulatory proto... more Military communication relies on robust and secure physical links that adhere to regulatory protocols and standards for communication. In unfamiliar terrain or hostile conditions these physical links can undergo deep-fading or intentional signal jamming, deteriorating the ongoing communication. Traditional retransmission technology or power adaptation would not be applicable to correct the outages seen in such scenarios, and often relays have been sought out as the solution. However given the exigency related to in-battle military communications, the latency with relaying cannot be tolerated and designing a scheme that is time-efficient is crucial. To this end, we discuss a practical approach to establishing bi-directional communication via a support node that acts a partial relay to the stranded military units, while maintaining its ongoing communication. This is possible through the use of a broadcast spatial multiplexing protocol implemented through space-time block coding at the relay. Our simulation results show us improved BER (bit-error rate) performance than the perfect direct link for high-SNR (signal-to-noise ratio) regimes, and comparable performance across the spectrum. We also demonstrate that our scheme is impervious to power a synchronicities between the stranded military nodes.
To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined t... more To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined the Positioning Reference Signal (PRS), which can be used to measure Time of Arrival (TOA) for downlink positioning. However, Orthogonal Frequency Division Multiplexing (OFDM) signals are sensitive and vulnerable to synchronization errors. Moreover, the highly configurable 5G PRS in Release 16 calls for a unique allocation pattern on the subcarriers. Existing timing recovery methods that have been employed for reference signals, which are evenly inserted in the subcarrier symbols, may not perform well. To solve the timing recovery issue of the OFDM signal through 5G standard-compliant PRS, we propose a three-stage timing recovery scheme. We use the 5G PRS as pilot symbols to estimate the path time delay and complete receiver sampling clock synchronization. We propose a generalized path time delay estimation method that can correct timing errors larger than one sample. In addition, we incorporate a delay-locked loop (DLL) that can track the PRS code-phase when the phase errors are within one sample, which showcases the precise positioning possible with a standard-compliant 5G New Radio (NR) signal.
ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper... more ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper, we consider a novel proactive sensing scheme that helps combat the hidden-node problem, while increasing certainty in the decision of spectrum occupancy. We extend this scheme by limiting the power of the probing signal used in carrying out proactive detection, with constraints set based on the interference threshold of the primary receiver. In protecting the licensed user from undue interference, and meeting the cognitive user's needs, simulation results show that power control is both a practical and constructive step forward in research in this new proactive scheme.
Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cog... more Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cognitive radios have been seen as a solution to occupy the gaps in the licensed spectrum through opportunistic spectrum access and simultaneous spectrum sharing techniques. For this purpose, spectrum sensing has been vital in providing accurate statistical information regarding licensed or primary user (PU) activity on its spectrum. In this paper, we design new sensing thresholds that take into account the outage caused to the PU as a consequence of cognitive or secondary users (SU) accessing or sharing the said spectrum. With these new thresholds, we can see more protection to the PU from SU spectrum access transmissions based on missed detections, and eliminate most common assumptions made with spectrum sharing systems. Our thresholds also work with a dynamic decision-making algorithm that allows the SUs to use only the statistical sensing information to understand the network dynamics, and determine its transmission opportunities and corresponding power consumption, in a decentralized and uncooperative cross-layer network.
2021 IEEE Wireless Communications and Networking Conference (WCNC)
To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined t... more To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined the Positioning Reference Signal (PRS), which can be used to measure Time of Arrival (TOA) for downlink positioning. However, Orthogonal Frequency Division Multiplexing (OFDM) signals are sensitive and vulnerable to synchronization errors. Moreover, the highly configurable 5G PRS in Release 16 calls for a unique allocation pattern on the subcarriers. Existing timing recovery methods that have been employed for reference signals, which are evenly inserted in the subcarrier symbols, may not perform well. To solve the timing recovery issue of the OFDM signal through 5G standard-compliant PRS, we propose a three-stage timing recovery scheme. We use the 5G PRS as pilot symbols to estimate the path time delay and complete receiver sampling clock synchronization. We propose a generalized path time delay estimation method that can correct timing errors larger than one sample. In addition, we incorporate a delay-locked loop (DLL) that can track the PRS code-phase when the phase errors are within one sample, which showcases the precise positioning possible with a standard-compliant 5G New Radio (NR) signal.
2021 IEEE Wireless Communications and Networking Conference (WCNC), 2021
In this paper, we propose a multi-level localization algorithm that breaks a centralized localiza... more In this paper, we propose a multi-level localization algorithm that breaks a centralized localization problem into a cluster-level distributed localization problem, where each cluster is a centralized unit. In contrast to fully distributed localization, the cluster-level distributed scheme results in reduction in contention, communication overheads, convergence time and energy consumption because cluster heads are responsible for the intracluster positioning on behalf of the whole cluster. To generate a global map, the cluster heads communicate with their direct neighbors to carry out inter-cluster ranging and positioning. The proposed method is suitable for large ad-hoc networks where most agents are low-cost, low-power RF transceivers used for ranging only while some agents are integrated with microcomputers such as Raspberry Pis capable of running intra and inter-cluster localization algorithms. The proposed system can work without anchor nodes and thus it can be deployed in the environments such as urban canyon, inside multi-story buildings, airports, and underground shopping malls where access to anchors or Global Navigation Satellite System (GNSS) is limited or prohibitive. We exploit a hybrid of two well-known methods: multidimensional scaling (MDS) and extended Kalman filtering (EKF) to effectively construct local and global position maps, even in the absence of GNSS information, anchors, or a complete ranging matrix.
2011 IEEE International Conference on Communications (ICC), 2011
Prior work in implementing spectrum sharing sce- narios for cognitive radio networks has relied o... more Prior work in implementing spectrum sharing sce- narios for cognitive radio networks has relied on the unlikely assumption of full cross-channel knowledge made available to the cognitive transmitter (CT) and/or the target primary receiver (PR). However, estimation of this cross-channel knowledge is not only important from a practical stand-point, but also in limiting the real interference power felt at the PR due to concurrent CT transmissions. We propose a supervised probing and sensing model, which enables the CT to gain a decent estimate of the cross-channel, assess the spectrum opportunities in its region of interference, and according to its throughput needs safely share or access primary user spectrum. With the probing power playing an essential part in the probing model, its optimization with respect to cross-channel estimation success and its influence on mean square error of the cross-channel estimation are discussed.
Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cog... more Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cognitive radios have been seen as a solution to occupy the gaps in the licensed spectrum through opportunistic spectrum access and simultaneous spectrum sharing techniques. For this purpose, spectrum sensing has been vital in providing accurate statistical information regarding licensed or primary user (PU) activity on its spectrum. In this paper, we design new sensing thresholds that take into account the outage caused to the PU as a consequence of cognitive or secondary users (SU) accessing or sharing the said spectrum. With these new thresholds, we can see more protection to the PU from SU spectrum access transmissions based on missed detections, and eliminate most common assumptions made with spectrum sharing systems. Our thresholds also work with a dynamic decision-making algorithm that allows the SUs to use only the statistical sensing information to understand the network dynamics, and determine its transmission opportunities and corresponding power consumption, in a decentralized and uncooperative cross-layer network.
Spectrum utility efficiency is key in designing systems that can meet the heavier demands of band... more Spectrum utility efficiency is key in designing systems that can meet the heavier demands of bandwidth and data rate of future communication technologies. Shared spectrum techniques and collaborative protocols have thus been studied to better utilize already existing spectrum resources. In this paper, we present a spectrum trading approach that allows the licensed user's (LU) resources to be efficiently shared with the secondary user (SU) network in exchange for a monetary cost. The model is based on demand and supply economics, wherein the highest bidder for spectrum resource is awarded with transmission rights over licensed spectrum. The transmission opportunities for the SU consider every state of the licensed link, in the form of dynamic spectrum access (DSA), spectrum sharing, and relaying, each of which has an optimized cost that will maximize the returns for the LU. The numerical results backed by the analytical study show that this spectrum trading scheme allows for significant improvements in data rate and spectrum transmission opportunities than previous work conducted in either DSA or the spectrum sharing fields.
2014 IEEE Military Communications Conference, 2014
Military communication relies on robust and secure physical links that adhere to regulatory proto... more Military communication relies on robust and secure physical links that adhere to regulatory protocols and standards for communication. In unfamiliar terrain or hostile conditions these physical links can undergo deep-fading or intentional signal jamming, deteriorating the ongoing communication. Traditional retransmission technology or power adaptation would not be applicable to correct the outages seen in such scenarios, and often relays have been sought out as the solution. However given the exigency related to in-battle military communications, the latency with relaying cannot be tolerated and designing a scheme that is time-efficient is crucial. To this end, we discuss a practical approach to establishing bi-directional communication via a support node that acts a partial relay to the stranded military units, while maintaining its ongoing communication. This is possible through the use of a broadcast spatial multiplexing protocol implemented through space-time block coding at the relay. Our simulation results show us improved BER (bit-error rate) performance than the perfect direct link for high-SNR (signal-to-noise ratio) regimes, and comparable performance across the spectrum. We also demonstrate that our scheme is impervious to power a synchronicities between the stranded military nodes.
2010 4th International Conference on Signal Processing and Communication Systems, 2010
ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper... more ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper, we consider a novel proactive sensing scheme that helps combat the hidden-node problem, while increasing certainty in the decision of spectrum occupancy. We extend this scheme by limiting the power of the probing signal used in carrying out proactive detection, with constraints set based on the interference threshold of the primary receiver. In protecting the licensed user from undue interference, and meeting the cognitive user's needs, simulation results show that power control is both a practical and constructive step forward in research in this new proactive scheme.
Spectrum utility efficiency is key in designing systems that can meet the heavier demands of band... more Spectrum utility efficiency is key in designing systems that can meet the heavier demands of bandwidth and data rate of future communication technologies. Shared spectrum techniques and collaborative protocols have thus been studied to better utilize already existing spectrum resources. In this paper, we present a spectrum trading approach that allows the licensed user's (LU) resources to be efficiently shared with the secondary user (SU) network in exchange for a monetary cost. The model is based on demand and supply economics, wherein the highest bidder for spectrum resource is awarded with transmission rights over licensed spectrum. The transmission opportunities for the SU consider every state of the licensed link, in the form of dynamic spectrum access (DSA), spectrum sharing, and relaying, each of which has an optimized cost that will maximize the returns for the LU. The numerical results backed by the analytical study show that this spectrum trading scheme allows for significant improvements in data rate and spectrum transmission opportunities than previous work conducted in either DSA or the spectrum sharing fields.
Military communication relies on robust and secure physical links that adhere to regulatory proto... more Military communication relies on robust and secure physical links that adhere to regulatory protocols and standards for communication. In unfamiliar terrain or hostile conditions these physical links can undergo deep-fading or intentional signal jamming, deteriorating the ongoing communication. Traditional retransmission technology or power adaptation would not be applicable to correct the outages seen in such scenarios, and often relays have been sought out as the solution. However given the exigency related to in-battle military communications, the latency with relaying cannot be tolerated and designing a scheme that is time-efficient is crucial. To this end, we discuss a practical approach to establishing bi-directional communication via a support node that acts a partial relay to the stranded military units, while maintaining its ongoing communication. This is possible through the use of a broadcast spatial multiplexing protocol implemented through space-time block coding at the relay. Our simulation results show us improved BER (bit-error rate) performance than the perfect direct link for high-SNR (signal-to-noise ratio) regimes, and comparable performance across the spectrum. We also demonstrate that our scheme is impervious to power a synchronicities between the stranded military nodes.
To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined t... more To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined the Positioning Reference Signal (PRS), which can be used to measure Time of Arrival (TOA) for downlink positioning. However, Orthogonal Frequency Division Multiplexing (OFDM) signals are sensitive and vulnerable to synchronization errors. Moreover, the highly configurable 5G PRS in Release 16 calls for a unique allocation pattern on the subcarriers. Existing timing recovery methods that have been employed for reference signals, which are evenly inserted in the subcarrier symbols, may not perform well. To solve the timing recovery issue of the OFDM signal through 5G standard-compliant PRS, we propose a three-stage timing recovery scheme. We use the 5G PRS as pilot symbols to estimate the path time delay and complete receiver sampling clock synchronization. We propose a generalized path time delay estimation method that can correct timing errors larger than one sample. In addition, we incorporate a delay-locked loop (DLL) that can track the PRS code-phase when the phase errors are within one sample, which showcases the precise positioning possible with a standard-compliant 5G New Radio (NR) signal.
ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper... more ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper, we consider a novel proactive sensing scheme that helps combat the hidden-node problem, while increasing certainty in the decision of spectrum occupancy. We extend this scheme by limiting the power of the probing signal used in carrying out proactive detection, with constraints set based on the interference threshold of the primary receiver. In protecting the licensed user from undue interference, and meeting the cognitive user's needs, simulation results show that power control is both a practical and constructive step forward in research in this new proactive scheme.
Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cog... more Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cognitive radios have been seen as a solution to occupy the gaps in the licensed spectrum through opportunistic spectrum access and simultaneous spectrum sharing techniques. For this purpose, spectrum sensing has been vital in providing accurate statistical information regarding licensed or primary user (PU) activity on its spectrum. In this paper, we design new sensing thresholds that take into account the outage caused to the PU as a consequence of cognitive or secondary users (SU) accessing or sharing the said spectrum. With these new thresholds, we can see more protection to the PU from SU spectrum access transmissions based on missed detections, and eliminate most common assumptions made with spectrum sharing systems. Our thresholds also work with a dynamic decision-making algorithm that allows the SUs to use only the statistical sensing information to understand the network dynamics, and determine its transmission opportunities and corresponding power consumption, in a decentralized and uncooperative cross-layer network.
2021 IEEE Wireless Communications and Networking Conference (WCNC)
To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined t... more To facilitate 5G-based positioning applications, Release 16 of the 3GPP 5G standard has defined the Positioning Reference Signal (PRS), which can be used to measure Time of Arrival (TOA) for downlink positioning. However, Orthogonal Frequency Division Multiplexing (OFDM) signals are sensitive and vulnerable to synchronization errors. Moreover, the highly configurable 5G PRS in Release 16 calls for a unique allocation pattern on the subcarriers. Existing timing recovery methods that have been employed for reference signals, which are evenly inserted in the subcarrier symbols, may not perform well. To solve the timing recovery issue of the OFDM signal through 5G standard-compliant PRS, we propose a three-stage timing recovery scheme. We use the 5G PRS as pilot symbols to estimate the path time delay and complete receiver sampling clock synchronization. We propose a generalized path time delay estimation method that can correct timing errors larger than one sample. In addition, we incorporate a delay-locked loop (DLL) that can track the PRS code-phase when the phase errors are within one sample, which showcases the precise positioning possible with a standard-compliant 5G New Radio (NR) signal.
2021 IEEE Wireless Communications and Networking Conference (WCNC), 2021
In this paper, we propose a multi-level localization algorithm that breaks a centralized localiza... more In this paper, we propose a multi-level localization algorithm that breaks a centralized localization problem into a cluster-level distributed localization problem, where each cluster is a centralized unit. In contrast to fully distributed localization, the cluster-level distributed scheme results in reduction in contention, communication overheads, convergence time and energy consumption because cluster heads are responsible for the intracluster positioning on behalf of the whole cluster. To generate a global map, the cluster heads communicate with their direct neighbors to carry out inter-cluster ranging and positioning. The proposed method is suitable for large ad-hoc networks where most agents are low-cost, low-power RF transceivers used for ranging only while some agents are integrated with microcomputers such as Raspberry Pis capable of running intra and inter-cluster localization algorithms. The proposed system can work without anchor nodes and thus it can be deployed in the environments such as urban canyon, inside multi-story buildings, airports, and underground shopping malls where access to anchors or Global Navigation Satellite System (GNSS) is limited or prohibitive. We exploit a hybrid of two well-known methods: multidimensional scaling (MDS) and extended Kalman filtering (EKF) to effectively construct local and global position maps, even in the absence of GNSS information, anchors, or a complete ranging matrix.
2011 IEEE International Conference on Communications (ICC), 2011
Prior work in implementing spectrum sharing sce- narios for cognitive radio networks has relied o... more Prior work in implementing spectrum sharing sce- narios for cognitive radio networks has relied on the unlikely assumption of full cross-channel knowledge made available to the cognitive transmitter (CT) and/or the target primary receiver (PR). However, estimation of this cross-channel knowledge is not only important from a practical stand-point, but also in limiting the real interference power felt at the PR due to concurrent CT transmissions. We propose a supervised probing and sensing model, which enables the CT to gain a decent estimate of the cross-channel, assess the spectrum opportunities in its region of interference, and according to its throughput needs safely share or access primary user spectrum. With the probing power playing an essential part in the probing model, its optimization with respect to cross-channel estimation success and its influence on mean square error of the cross-channel estimation are discussed.
Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cog... more Efficiency in spectrum utility has been a concern in wireless communications for a long time. Cognitive radios have been seen as a solution to occupy the gaps in the licensed spectrum through opportunistic spectrum access and simultaneous spectrum sharing techniques. For this purpose, spectrum sensing has been vital in providing accurate statistical information regarding licensed or primary user (PU) activity on its spectrum. In this paper, we design new sensing thresholds that take into account the outage caused to the PU as a consequence of cognitive or secondary users (SU) accessing or sharing the said spectrum. With these new thresholds, we can see more protection to the PU from SU spectrum access transmissions based on missed detections, and eliminate most common assumptions made with spectrum sharing systems. Our thresholds also work with a dynamic decision-making algorithm that allows the SUs to use only the statistical sensing information to understand the network dynamics, and determine its transmission opportunities and corresponding power consumption, in a decentralized and uncooperative cross-layer network.
Spectrum utility efficiency is key in designing systems that can meet the heavier demands of band... more Spectrum utility efficiency is key in designing systems that can meet the heavier demands of bandwidth and data rate of future communication technologies. Shared spectrum techniques and collaborative protocols have thus been studied to better utilize already existing spectrum resources. In this paper, we present a spectrum trading approach that allows the licensed user's (LU) resources to be efficiently shared with the secondary user (SU) network in exchange for a monetary cost. The model is based on demand and supply economics, wherein the highest bidder for spectrum resource is awarded with transmission rights over licensed spectrum. The transmission opportunities for the SU consider every state of the licensed link, in the form of dynamic spectrum access (DSA), spectrum sharing, and relaying, each of which has an optimized cost that will maximize the returns for the LU. The numerical results backed by the analytical study show that this spectrum trading scheme allows for significant improvements in data rate and spectrum transmission opportunities than previous work conducted in either DSA or the spectrum sharing fields.
2014 IEEE Military Communications Conference, 2014
Military communication relies on robust and secure physical links that adhere to regulatory proto... more Military communication relies on robust and secure physical links that adhere to regulatory protocols and standards for communication. In unfamiliar terrain or hostile conditions these physical links can undergo deep-fading or intentional signal jamming, deteriorating the ongoing communication. Traditional retransmission technology or power adaptation would not be applicable to correct the outages seen in such scenarios, and often relays have been sought out as the solution. However given the exigency related to in-battle military communications, the latency with relaying cannot be tolerated and designing a scheme that is time-efficient is crucial. To this end, we discuss a practical approach to establishing bi-directional communication via a support node that acts a partial relay to the stranded military units, while maintaining its ongoing communication. This is possible through the use of a broadcast spatial multiplexing protocol implemented through space-time block coding at the relay. Our simulation results show us improved BER (bit-error rate) performance than the perfect direct link for high-SNR (signal-to-noise ratio) regimes, and comparable performance across the spectrum. We also demonstrate that our scheme is impervious to power a synchronicities between the stranded military nodes.
2010 4th International Conference on Signal Processing and Communication Systems, 2010
ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper... more ABSTRACT Spectrum sensing plays a vital part in cognitive radio (CR) communication. In this paper, we consider a novel proactive sensing scheme that helps combat the hidden-node problem, while increasing certainty in the decision of spectrum occupancy. We extend this scheme by limiting the power of the probing signal used in carrying out proactive detection, with constraints set based on the interference threshold of the primary receiver. In protecting the licensed user from undue interference, and meeting the cognitive user's needs, simulation results show that power control is both a practical and constructive step forward in research in this new proactive scheme.
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