Hamid Ahmadi - Academia.edu (original) (raw)
Papers by Hamid Ahmadi
International Journal of Civil and Structural Engineering, 2012
2012 IEEE Statistical Signal Processing Workshop (SSP), 2012
ABSTRACT We consider parallel binary distributed detection in a wireless sensor network, in which... more ABSTRACT We consider parallel binary distributed detection in a wireless sensor network, in which sensors send their binary phase shift keying (PSK) modulated decisions to the fusion center (FC) over communication channels, that are subject to Rayleigh fading and noise. The FC is tasked with detecting the presence of a Gaussian signal source. When it is present, sensors' observations are spatially correlated samples of the signal source, corrupted by Gaussian noises. Using identical energy detectors as local decision rules, we derive a linear fusion rule that combines likelihood ratios of received signals at the FC and maximizes modified deflection coefficient. Our numerical results show that at high signal-to-noise (SNR) regime, this rule outperforms the linear fusion rule which only combines the outputs of wireless communication channels.
2009 12th Euromicro Conference on Digital System Design, Architectures, Methods and Tools, 2009
2009 IEEE 10th Workshop on Signal Processing Advances in Wireless Communications, 2009
Page 1. CHANNEL AWARE SENSOR SELECTION IN DISTRIBUTED DETECTION SYSTEMS Hamid R. Ahmadi and Azade... more Page 1. CHANNEL AWARE SENSOR SELECTION IN DISTRIBUTED DETECTION SYSTEMS Hamid R. Ahmadi and Azadeh Vosoughi ECE Department, University of Rochester, Rochester, NY 14627 ABSTRACT We propose ...
MILCOM 2008 - 2008 IEEE Military Communications Conference, 2008
Page 1. Impact of Channel Estimation Error on Decentralized Detection in Bandwidth Constrained Wi... more Page 1. Impact of Channel Estimation Error on Decentralized Detection in Bandwidth Constrained Wireless Sensor Networks Hamid R. Ahmadi 1, Azadeh Vosoughi 2 ECE Department, University ofRochester, Rochester, NY 14627-0126. ...
Data Communication Systems and their Performance, 1991
Global Telecommunications Conference, . GLOBECOM . IEEE, 1989
Data Communication Systems and their Performance, 1991
2008 3rd International Design and Test Workshop, 2008
Abstract In this paper, we present a very low power standard public-key cryptography processor fo... more Abstract In this paper, we present a very low power standard public-key cryptography processor for use in power-limited applications. The proposed prime-field elliptic-curve cryptography processor is flexible in terms of field and curve parameters. The power ...
IEICE Electronics Express, 2010
... Hamid Reza Ahmadi 1 , Ali Afzali-Kusha 1 , and Massoud Pedram 2 ... [4] SS Kumar, Elliptic C... more ... Hamid Reza Ahmadi 1 , Ali Afzali-Kusha 1 , and Massoud Pedram 2 ... [4] SS Kumar, Elliptic Curve Cryptography For Constrained Devices, Ph.D. dissertation, Electrical Engineering and Information Technology Department, Ruhr-University, Bochum, Germany, June 2006. ...
IEEE Transactions on Wireless Communications, 2000
ABSTRACT We consider a distributed detection system, in which sensors send their decisions over o... more ABSTRACT We consider a distributed detection system, in which sensors send their decisions over orthogonal noisy channels to a fusion center (FC). We study how the optimal integrated fusion rule and its low signal-to-noise ratio (SNR) approximation, as well as the suboptimal non-integrated fusion rule, are related to the physical layer specifications (reception, modulation, channel model, and availability of channel state information (CSI) at FC). In particular, we consider training and non-training based systems and investigate the effect of imperfect CSI on the fusion rules, detection performance and error exponent, assuming that the sum of training and data symbol transmit powers is fixed. Our results show that the detection performance of the system with noncoherent reception is maximized when training symbol transmit power is zero. This performance is attainable with the statistics-based likelihood ratio test (LRT) rule for random channel model and the generalized LRT rule for deterministic channel model. For a system with BPSK modulation and coherent reception, subject to Rayleigh fading, the detection probability and error exponent are maximized when half of transmit power is allocated for training symbol. For Rician fading, however, optimal power allocation between training and decision symbols depends on the SNR and Rice factor. Comparing the integrated and non-integrated fusion rules, we show that the former always outperforms the latter.
IEEE Transactions on Signal Processing, 2000
This paper investigates the increase in detection reliability that an adaptive network (with adap... more This paper investigates the increase in detection reliability that an adaptive network (with adaptive topology and channel-dependent decision and fusion rules) can provide, compared with a fixed topology network. We consider a network, consisting of local detectors and a fusion center (FC), that is tasked with accessing the presence or absence of a phenomenon of interest (POI) at a specific
IEEE Signal Processing Letters, 2000
ABSTRACT We consider a binary distributed detection problem in a wireless sensor network with inh... more ABSTRACT We consider a binary distributed detection problem in a wireless sensor network with inhomogeneous sensors, in which sensors send their binary phase shift keying (BPSK) modulated decisions to the fusion center (FC) over orthogonal channels that are subject to pathloss, Rayleigh fading, and Gaussian noise. Assuming training based channel estimation, we consider a linear fusion rule which employs imperfect channel state information (CSI) to form the global decision at the FC. Under the constraint that the total transmit power of training and decision symbols at each sensor is fixed, we analytically derive the optimal power allocation between training and data at each sensor such that the deflection coefficient at the FC is maximized. Our analysis shows that the proposed optimal power allocation scheme is a function of signal-to-noise (SNR) and local detection indices, and at high SNR regime, the proposed scheme outperforms the uniform power allocation.
Local Computer Networks, 1991. …, 1991
ABSTRACT: MetaRing is a Gigabitlsecond Local Area Network architecture based on a dual(bi-directi... more ABSTRACT: MetaRing is a Gigabitlsecond Local Area Network architecture based on a dual(bi-directional) op-tical fiber ring with spatial reuse mechanism. Concurrent access and spatial reuse enable simultaneous trans-missions over disjoint segments of a ...
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](… Annual Joint Conference of the IEEE …, 1988
Signals, Circuits and …, 2003
AN 8 BIT, 150 MS/S FOLDING AND INTERPOLATING ADC IN 0.25pm CMOS WITH RESISTIVE AVERAGING ... Hami... more AN 8 BIT, 150 MS/S FOLDING AND INTERPOLATING ADC IN 0.25pm CMOS WITH RESISTIVE AVERAGING ... Hamid R. Ahmadi, Omid Shoaei. and M. Yaser Azizi University of Tehran, ECE Dept., Integrated Circuit Lab oratory, POBox 14395-515, Tehran, Iran. Email: ...
Selected Areas in …, 1994
Journal of High Speed …, 1996
... Collaborative Colleagues: Hamid Ahmadi: colleagues. Arvind Krishna: colleagues.
International Journal of Civil and Structural Engineering, 2012
2012 IEEE Statistical Signal Processing Workshop (SSP), 2012
ABSTRACT We consider parallel binary distributed detection in a wireless sensor network, in which... more ABSTRACT We consider parallel binary distributed detection in a wireless sensor network, in which sensors send their binary phase shift keying (PSK) modulated decisions to the fusion center (FC) over communication channels, that are subject to Rayleigh fading and noise. The FC is tasked with detecting the presence of a Gaussian signal source. When it is present, sensors' observations are spatially correlated samples of the signal source, corrupted by Gaussian noises. Using identical energy detectors as local decision rules, we derive a linear fusion rule that combines likelihood ratios of received signals at the FC and maximizes modified deflection coefficient. Our numerical results show that at high signal-to-noise (SNR) regime, this rule outperforms the linear fusion rule which only combines the outputs of wireless communication channels.
2009 12th Euromicro Conference on Digital System Design, Architectures, Methods and Tools, 2009
2009 IEEE 10th Workshop on Signal Processing Advances in Wireless Communications, 2009
Page 1. CHANNEL AWARE SENSOR SELECTION IN DISTRIBUTED DETECTION SYSTEMS Hamid R. Ahmadi and Azade... more Page 1. CHANNEL AWARE SENSOR SELECTION IN DISTRIBUTED DETECTION SYSTEMS Hamid R. Ahmadi and Azadeh Vosoughi ECE Department, University of Rochester, Rochester, NY 14627 ABSTRACT We propose ...
MILCOM 2008 - 2008 IEEE Military Communications Conference, 2008
Page 1. Impact of Channel Estimation Error on Decentralized Detection in Bandwidth Constrained Wi... more Page 1. Impact of Channel Estimation Error on Decentralized Detection in Bandwidth Constrained Wireless Sensor Networks Hamid R. Ahmadi 1, Azadeh Vosoughi 2 ECE Department, University ofRochester, Rochester, NY 14627-0126. ...
Data Communication Systems and their Performance, 1991
Global Telecommunications Conference, . GLOBECOM . IEEE, 1989
Data Communication Systems and their Performance, 1991
2008 3rd International Design and Test Workshop, 2008
Abstract In this paper, we present a very low power standard public-key cryptography processor fo... more Abstract In this paper, we present a very low power standard public-key cryptography processor for use in power-limited applications. The proposed prime-field elliptic-curve cryptography processor is flexible in terms of field and curve parameters. The power ...
IEICE Electronics Express, 2010
... Hamid Reza Ahmadi 1 , Ali Afzali-Kusha 1 , and Massoud Pedram 2 ... [4] SS Kumar, Elliptic C... more ... Hamid Reza Ahmadi 1 , Ali Afzali-Kusha 1 , and Massoud Pedram 2 ... [4] SS Kumar, Elliptic Curve Cryptography For Constrained Devices, Ph.D. dissertation, Electrical Engineering and Information Technology Department, Ruhr-University, Bochum, Germany, June 2006. ...
IEEE Transactions on Wireless Communications, 2000
ABSTRACT We consider a distributed detection system, in which sensors send their decisions over o... more ABSTRACT We consider a distributed detection system, in which sensors send their decisions over orthogonal noisy channels to a fusion center (FC). We study how the optimal integrated fusion rule and its low signal-to-noise ratio (SNR) approximation, as well as the suboptimal non-integrated fusion rule, are related to the physical layer specifications (reception, modulation, channel model, and availability of channel state information (CSI) at FC). In particular, we consider training and non-training based systems and investigate the effect of imperfect CSI on the fusion rules, detection performance and error exponent, assuming that the sum of training and data symbol transmit powers is fixed. Our results show that the detection performance of the system with noncoherent reception is maximized when training symbol transmit power is zero. This performance is attainable with the statistics-based likelihood ratio test (LRT) rule for random channel model and the generalized LRT rule for deterministic channel model. For a system with BPSK modulation and coherent reception, subject to Rayleigh fading, the detection probability and error exponent are maximized when half of transmit power is allocated for training symbol. For Rician fading, however, optimal power allocation between training and decision symbols depends on the SNR and Rice factor. Comparing the integrated and non-integrated fusion rules, we show that the former always outperforms the latter.
IEEE Transactions on Signal Processing, 2000
This paper investigates the increase in detection reliability that an adaptive network (with adap... more This paper investigates the increase in detection reliability that an adaptive network (with adaptive topology and channel-dependent decision and fusion rules) can provide, compared with a fixed topology network. We consider a network, consisting of local detectors and a fusion center (FC), that is tasked with accessing the presence or absence of a phenomenon of interest (POI) at a specific
IEEE Signal Processing Letters, 2000
ABSTRACT We consider a binary distributed detection problem in a wireless sensor network with inh... more ABSTRACT We consider a binary distributed detection problem in a wireless sensor network with inhomogeneous sensors, in which sensors send their binary phase shift keying (BPSK) modulated decisions to the fusion center (FC) over orthogonal channels that are subject to pathloss, Rayleigh fading, and Gaussian noise. Assuming training based channel estimation, we consider a linear fusion rule which employs imperfect channel state information (CSI) to form the global decision at the FC. Under the constraint that the total transmit power of training and decision symbols at each sensor is fixed, we analytically derive the optimal power allocation between training and data at each sensor such that the deflection coefficient at the FC is maximized. Our analysis shows that the proposed optimal power allocation scheme is a function of signal-to-noise (SNR) and local detection indices, and at high SNR regime, the proposed scheme outperforms the uniform power allocation.
Local Computer Networks, 1991. …, 1991
ABSTRACT: MetaRing is a Gigabitlsecond Local Area Network architecture based on a dual(bi-directi... more ABSTRACT: MetaRing is a Gigabitlsecond Local Area Network architecture based on a dual(bi-directional) op-tical fiber ring with spatial reuse mechanism. Concurrent access and spatial reuse enable simultaneous trans-missions over disjoint segments of a ...
… Annual Joint Conference of the IEEE …, 1988
Signals, Circuits and …, 2003
AN 8 BIT, 150 MS/S FOLDING AND INTERPOLATING ADC IN 0.25pm CMOS WITH RESISTIVE AVERAGING ... Hami... more AN 8 BIT, 150 MS/S FOLDING AND INTERPOLATING ADC IN 0.25pm CMOS WITH RESISTIVE AVERAGING ... Hamid R. Ahmadi, Omid Shoaei. and M. Yaser Azizi University of Tehran, ECE Dept., Integrated Circuit Lab oratory, POBox 14395-515, Tehran, Iran. Email: ...
Selected Areas in …, 1994
Journal of High Speed …, 1996
... Collaborative Colleagues: Hamid Ahmadi: colleagues. Arvind Krishna: colleagues.