International Conference on Acoustics, Speech, and Signal Processing, Jan 13, 2003
A study is made of a cross-coupled phase-locked loop (CCPLL) used for separation of close sinusoi... more A study is made of a cross-coupled phase-locked loop (CCPLL) used for separation of close sinusoids with slowly varying frequencies. It is assumed that the sinusoids have equal amplitudes, and it is shown that the CCPLL system can effectively separate two sine signals with an observation interval T<1/ Delta f. An analysis in the presence of noise is also given. It is shown that a satisfactory phase estimation can be achieved for SNR >or=15 dB. The result has application in fields such as ranging, symbol synchronization, and carrier recovery for coherent demodulation.<<ETX>>
The closed-loop self-synchronized constrained notch filter (CLSS-CNF) is proposed, and its abilit... more The closed-loop self-synchronized constrained notch filter (CLSS-CNF) is proposed, and its ability for retrieval of narrowband signals corrupted by a strong FM interference is studied. Self-synchronization is achieved through the estimation of the instantaneous phase of the FM interference to control time-varying coefficients of SC-CNF by using a closed-loop structure. The CLSS-CNF can overcome the tracking capability threshold of a
A Multiple Input Single Output (MISO) system based on Maximum Ratio Transmission (MRT) precoding ... more A Multiple Input Single Output (MISO) system based on Maximum Ratio Transmission (MRT) precoding with nonlinear Power Amplifiers (PAs) is considered. The nonlinear PAs distort the transmitted signal causing performance degradation. The common approach to mitigating nonlinear distortions is linearization of the PAs. For the MISO system we propose to apply a more generic approach in the form of an entire nonlinear MISO channel linearization, applied jointly for all PAs. It is shown that the results of this approach outperform those of the approach based on local linearization of each PA separately. An iterative technique is proposed to implement the entire MISO channel linearization. This technique requires knowledge of the channel state information and a model of the PAs at the transmitter. The performance of separate local and collective joint linearization is evaluated and compared in terms of the Symbol Error Rate (SER).
2015 IEEE Global Communications Conference (GLOBECOM), Dec 1, 2015
... A. PAR It is well known that when is large, the transmit multi-carrier signals in (1 ... the ... more ... A. PAR It is well known that when is large, the transmit multi-carrier signals in (1 ... the se-quential signal transmission into independent symbols allows working with each multicarrier vector independently. ... We will assume that the out-of-band terms are filtered at the receiver input ...
In this work we consider an OFDM-SDMA downlink with a real life, nonlinear Power Amplifier (PA). ... more In this work we consider an OFDM-SDMA downlink with a real life, nonlinear Power Amplifier (PA). It is well known that a nonlinear PA produces nonlinear distortions. We propose a novel iterative algorithm based on Zero Forcing (ZF) precoding to cancel the nonlinear distortions seen at the mobile devices while preserving the interference-free reception due to ZF. The proposed algorithm also keeps the out-of-band radiation of the transmitted signals low, in order to satisfy spectral purity requirements. For a low Back-Off (BO) scenario, where the nonlinear distortions are strong, the proposed algorithm shows a much lower Symbol Error Rate (SER) and much higher power efficiency than the well known ZF-SDMA with a real life PA.
The influence of nonlinear power amplifiers (PAs) on the performance of multiple-input multiple-o... more The influence of nonlinear power amplifiers (PAs) on the performance of multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems is investigated. A “full” MIMO scheme with transmitters (TX) precoding and receivers (RX) decoding is considered. It is shown, under assumption of high order OFDM and frequency selective channel, that the ratio between the useful signal and the nonlinear distortions is proportional to the number of TX antennas, i.e., the influence of the nonlinear distortions decreases as the number of TX antennas increases. The distortion reduction factor (DRF) is proposed as a performance metric for MIMO-OFDM systems with nonlinear PAs. A general formula for signal to distortion and noise ratio is obtained for the nonlinear PA with memory, described by the Wiener-Hammerstein (WH) model. Special cases of MIMO, such as maximum ratio transmission (MRT) and maximum ratio combining (MRC), are considered. A full agreement between the theoretical and simulation results is obtained. The main contribution of this paper is in a statement that TX processing reduces the effect of nonlinear distortions. This is obtained by novel approach for analysis of the MIMO-OFDM systems with nonlinear PAs with memory.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, Jul 1, 2017
Breathing monitors have become the all-important cornerstone of a wide variety of commercial and ... more Breathing monitors have become the all-important cornerstone of a wide variety of commercial and personal safety applications, ranging from elderly care to baby monitoring. Many such monitors exist in the market, some, with vital signs monitoring capabilities, but none remote. This paper presents a simple, yet efficient, real time method of extracting the subject's breathing sinus rhythm. Points of interest are detected on the subject's body, and the corresponding optical flow is estimated and tracked using the well known Lucas-Kanade algorithm on a frame by frame basis. A generalized likelihood ratio test is then utilized on each of the many interest points to detect which is moving in harmonic fashion. Finally, a spectral estimation algorithm based on Pisarenko harmonic decomposition tracks the harmonic frequency in real time, and a fusion maximum likelihood algorithm optimally estimates the breathing rate using all points considered. The results show a maximal error of 1 ...
2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014
The influence of a nonlinear power amplifier on the performance of OFDM-MRT is investigated. It i... more The influence of a nonlinear power amplifier on the performance of OFDM-MRT is investigated. It is shown that the ratio between the useful signal and the nonlinear distortions is proportional to the number of TX antennas, i.e., the influence of the nonlinear distortions decreases as the number of TX antennas increases. The Distortion Reduction Factor (DRF) is proposed as a performance metric for multi-antenna systems with nonlinear power amplifier. Considering the nonlinear power amplifier in each transmitting branch, a general formula for signal to distortions and noise ratio in the receiver is obtained and symbol error rate is computed. The MRT is compared to MRC and SISO. It is shown that for a low noise scenario the performance of MRT is much better than that of MRC. Full agreement of the theoretical and simulation results is obtained.
2020 IEEE Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS)
Remote sensing of elderlies' call for help is of great interest to caregivers, the elderly... more Remote sensing of elderlies' call for help is of great interest to caregivers, the elderly's family, and, of course, to the elderly who most often doesn't want to be bothered with a wearable device or cannot physically reach the panic button. According to the center for disease control and prevention (CDC), 2.5 million elderlies are treated in emergency rooms due to fall injuries. Personal emergency response systems (PERS), also known as panic buttons or medical alerts, are very common in the industry. Some of them require the injured person to operate, some are passive but have to be on the injured person body in the form of a necklace or a wrist band. We propose a single transmitter (TX), single receiver (RX), fully remote ultrasonic radar system for classifying a call for help signal, which only requires the person to wave one of her/his hands for 3 seconds. A simple, yet robust algorithm is employed to classify the movement extracted out of the phase of the received signal emitted from a 40 kHz continuous-wave (CW) ultrasonic transmitter. The proposed algorithm is highly immune to thermal noise and employs a novel real time, optimal Doppler estimation without the use of spectral analysis algorithms such as the Fourier transform.
ABSTRACT This paper investigates the achievable rate of multicarrier systems with non-linear dist... more ABSTRACT This paper investigates the achievable rate of multicarrier systems with non-linear distortion caused by high power amplifier (HPA) at the transmitter. We derive mutual information expressions for several non-linear models of HPA. Specific results are given for different values of the input backoff. It is shown that for some cases, linearization of HPA is not the best strategy.
2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2017
This paper deals with a Maximum Likelihood (ML) receiver for a Single Carrier (SC) signal distort... more This paper deals with a Maximum Likelihood (ML) receiver for a Single Carrier (SC) signal distorted by a nonlinear Power Amplifier (PA). The well known optimal Matched Filter (MF) loses its optimality when a nonlinear PA is considered. We first propose an optimal receiver based on the ML criterion taking into account the PA nonlinearity. In case of a Additive White Gaussian Noise (AWGN), the ML receiver has to find the minimum Euclidean distance between the received vector and all nonlinearly distorted vectors that the transmitter may send. The exhaustive search solution of this problem has exponential complexity. To reduce the complexity, we propose a sub-optimal receiver that minimizes the Euclidean distance, seen as a cost function, using the Gradient Descent (GD) algorithm. We also present a low complexity version of the GD based receiver which is suitable for a parallel processing implementation. Comparative study of Symbol Error Rate (SER) performance of the proposed receiver against the optimal SC MF based receiver is given.
2016 IEEE International Conference on the Science of Electrical Engineering (ICSEE), 2016
OFDM signal suffers from high Peak to Average Power Ratio (PAPR). This dictates the necessity to ... more OFDM signal suffers from high Peak to Average Power Ratio (PAPR). This dictates the necessity to drive the nonlinear power amplifier with high back-off, which leads to low power amplifier efficiency. In this paper we consider system that contains Iterative Clipping and Filtering (ICF) at the transmitter for PAPR reduction and modified iterative receiver (MIR) for demodulation. The MIR demodulate the distorted received signal. The distortions are created by the ICF and the nonlinear PA. The system architecture provides two main degrees of freedom given by the two back-offs: BO1 for ICF and BO2 for the power amplifier. We suggest to exploit these degrees of freedom in order to optimize the system performance expressed by a triplet: power efficiency (PE), adjacent channel power ratio (ACPR) and symbol error rate (SER). The optimal pair [BO1 BO2] depends on the priority among ACPR, SER and PE. Once the priority is determined, the optimal pair [BO1 BO2] that optimizes the system performa...
A method of retrieval of a multitone corrupted by a strong wide-band FM interference is presented... more A method of retrieval of a multitone corrupted by a strong wide-band FM interference is presented. The input mixture is transformed into a new time domain, resulting in a concentration of the FM interference around a chosen frequency; this interference is then rejected by a constrained notch filter with a fixed notch point. Time warping is implemented through nonequally spaced sampling. The proposed method provides results superior to those of conventional adaptive processing, which fails to track the parameters of an FM interference with significantly large frequency deviations.
1996 8th European Signal Processing Conference (EUSIPCO 1996), 1996
The spectral subtraction approach has become almost standard in speech enhancement because it is ... more The spectral subtraction approach has become almost standard in speech enhancement because it is relatively easy to understand and implement. The major drawback of the spectral subtraction method is that it leaves residual noise with annoying noticeable tonal characteristics referred to as musical noise. For low SNR the perceived effect of the "musical noise" is close to that of the additive noise. In the present work we propose to reduce the musical noise by applying the output of a standard spectral subtractor to a constrained high order notch filter which suppresses the "musical noise". The filtration process distorts the speech signal. It is possible to reduce the level of distortion if the speech signal is preprocessed properly before it is contaminated by the noise. It will be demonstrated that the proposed method is superior to the standard spectral subtraction specially for low SNR. A comprehensive listening test indicated that for segmental SNR= −12dB, 7...
International Conference on Acoustics, Speech, and Signal Processing, Jan 13, 2003
A study is made of a cross-coupled phase-locked loop (CCPLL) used for separation of close sinusoi... more A study is made of a cross-coupled phase-locked loop (CCPLL) used for separation of close sinusoids with slowly varying frequencies. It is assumed that the sinusoids have equal amplitudes, and it is shown that the CCPLL system can effectively separate two sine signals with an observation interval T<1/ Delta f. An analysis in the presence of noise is also given. It is shown that a satisfactory phase estimation can be achieved for SNR >or=15 dB. The result has application in fields such as ranging, symbol synchronization, and carrier recovery for coherent demodulation.<<ETX>>
The closed-loop self-synchronized constrained notch filter (CLSS-CNF) is proposed, and its abilit... more The closed-loop self-synchronized constrained notch filter (CLSS-CNF) is proposed, and its ability for retrieval of narrowband signals corrupted by a strong FM interference is studied. Self-synchronization is achieved through the estimation of the instantaneous phase of the FM interference to control time-varying coefficients of SC-CNF by using a closed-loop structure. The CLSS-CNF can overcome the tracking capability threshold of a
A Multiple Input Single Output (MISO) system based on Maximum Ratio Transmission (MRT) precoding ... more A Multiple Input Single Output (MISO) system based on Maximum Ratio Transmission (MRT) precoding with nonlinear Power Amplifiers (PAs) is considered. The nonlinear PAs distort the transmitted signal causing performance degradation. The common approach to mitigating nonlinear distortions is linearization of the PAs. For the MISO system we propose to apply a more generic approach in the form of an entire nonlinear MISO channel linearization, applied jointly for all PAs. It is shown that the results of this approach outperform those of the approach based on local linearization of each PA separately. An iterative technique is proposed to implement the entire MISO channel linearization. This technique requires knowledge of the channel state information and a model of the PAs at the transmitter. The performance of separate local and collective joint linearization is evaluated and compared in terms of the Symbol Error Rate (SER).
2015 IEEE Global Communications Conference (GLOBECOM), Dec 1, 2015
... A. PAR It is well known that when is large, the transmit multi-carrier signals in (1 ... the ... more ... A. PAR It is well known that when is large, the transmit multi-carrier signals in (1 ... the se-quential signal transmission into independent symbols allows working with each multicarrier vector independently. ... We will assume that the out-of-band terms are filtered at the receiver input ...
In this work we consider an OFDM-SDMA downlink with a real life, nonlinear Power Amplifier (PA). ... more In this work we consider an OFDM-SDMA downlink with a real life, nonlinear Power Amplifier (PA). It is well known that a nonlinear PA produces nonlinear distortions. We propose a novel iterative algorithm based on Zero Forcing (ZF) precoding to cancel the nonlinear distortions seen at the mobile devices while preserving the interference-free reception due to ZF. The proposed algorithm also keeps the out-of-band radiation of the transmitted signals low, in order to satisfy spectral purity requirements. For a low Back-Off (BO) scenario, where the nonlinear distortions are strong, the proposed algorithm shows a much lower Symbol Error Rate (SER) and much higher power efficiency than the well known ZF-SDMA with a real life PA.
The influence of nonlinear power amplifiers (PAs) on the performance of multiple-input multiple-o... more The influence of nonlinear power amplifiers (PAs) on the performance of multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems is investigated. A “full” MIMO scheme with transmitters (TX) precoding and receivers (RX) decoding is considered. It is shown, under assumption of high order OFDM and frequency selective channel, that the ratio between the useful signal and the nonlinear distortions is proportional to the number of TX antennas, i.e., the influence of the nonlinear distortions decreases as the number of TX antennas increases. The distortion reduction factor (DRF) is proposed as a performance metric for MIMO-OFDM systems with nonlinear PAs. A general formula for signal to distortion and noise ratio is obtained for the nonlinear PA with memory, described by the Wiener-Hammerstein (WH) model. Special cases of MIMO, such as maximum ratio transmission (MRT) and maximum ratio combining (MRC), are considered. A full agreement between the theoretical and simulation results is obtained. The main contribution of this paper is in a statement that TX processing reduces the effect of nonlinear distortions. This is obtained by novel approach for analysis of the MIMO-OFDM systems with nonlinear PAs with memory.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, Jul 1, 2017
Breathing monitors have become the all-important cornerstone of a wide variety of commercial and ... more Breathing monitors have become the all-important cornerstone of a wide variety of commercial and personal safety applications, ranging from elderly care to baby monitoring. Many such monitors exist in the market, some, with vital signs monitoring capabilities, but none remote. This paper presents a simple, yet efficient, real time method of extracting the subject's breathing sinus rhythm. Points of interest are detected on the subject's body, and the corresponding optical flow is estimated and tracked using the well known Lucas-Kanade algorithm on a frame by frame basis. A generalized likelihood ratio test is then utilized on each of the many interest points to detect which is moving in harmonic fashion. Finally, a spectral estimation algorithm based on Pisarenko harmonic decomposition tracks the harmonic frequency in real time, and a fusion maximum likelihood algorithm optimally estimates the breathing rate using all points considered. The results show a maximal error of 1 ...
2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014
The influence of a nonlinear power amplifier on the performance of OFDM-MRT is investigated. It i... more The influence of a nonlinear power amplifier on the performance of OFDM-MRT is investigated. It is shown that the ratio between the useful signal and the nonlinear distortions is proportional to the number of TX antennas, i.e., the influence of the nonlinear distortions decreases as the number of TX antennas increases. The Distortion Reduction Factor (DRF) is proposed as a performance metric for multi-antenna systems with nonlinear power amplifier. Considering the nonlinear power amplifier in each transmitting branch, a general formula for signal to distortions and noise ratio in the receiver is obtained and symbol error rate is computed. The MRT is compared to MRC and SISO. It is shown that for a low noise scenario the performance of MRT is much better than that of MRC. Full agreement of the theoretical and simulation results is obtained.
2020 IEEE Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS)
Remote sensing of elderlies' call for help is of great interest to caregivers, the elderly... more Remote sensing of elderlies' call for help is of great interest to caregivers, the elderly's family, and, of course, to the elderly who most often doesn't want to be bothered with a wearable device or cannot physically reach the panic button. According to the center for disease control and prevention (CDC), 2.5 million elderlies are treated in emergency rooms due to fall injuries. Personal emergency response systems (PERS), also known as panic buttons or medical alerts, are very common in the industry. Some of them require the injured person to operate, some are passive but have to be on the injured person body in the form of a necklace or a wrist band. We propose a single transmitter (TX), single receiver (RX), fully remote ultrasonic radar system for classifying a call for help signal, which only requires the person to wave one of her/his hands for 3 seconds. A simple, yet robust algorithm is employed to classify the movement extracted out of the phase of the received signal emitted from a 40 kHz continuous-wave (CW) ultrasonic transmitter. The proposed algorithm is highly immune to thermal noise and employs a novel real time, optimal Doppler estimation without the use of spectral analysis algorithms such as the Fourier transform.
ABSTRACT This paper investigates the achievable rate of multicarrier systems with non-linear dist... more ABSTRACT This paper investigates the achievable rate of multicarrier systems with non-linear distortion caused by high power amplifier (HPA) at the transmitter. We derive mutual information expressions for several non-linear models of HPA. Specific results are given for different values of the input backoff. It is shown that for some cases, linearization of HPA is not the best strategy.
2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2017
This paper deals with a Maximum Likelihood (ML) receiver for a Single Carrier (SC) signal distort... more This paper deals with a Maximum Likelihood (ML) receiver for a Single Carrier (SC) signal distorted by a nonlinear Power Amplifier (PA). The well known optimal Matched Filter (MF) loses its optimality when a nonlinear PA is considered. We first propose an optimal receiver based on the ML criterion taking into account the PA nonlinearity. In case of a Additive White Gaussian Noise (AWGN), the ML receiver has to find the minimum Euclidean distance between the received vector and all nonlinearly distorted vectors that the transmitter may send. The exhaustive search solution of this problem has exponential complexity. To reduce the complexity, we propose a sub-optimal receiver that minimizes the Euclidean distance, seen as a cost function, using the Gradient Descent (GD) algorithm. We also present a low complexity version of the GD based receiver which is suitable for a parallel processing implementation. Comparative study of Symbol Error Rate (SER) performance of the proposed receiver against the optimal SC MF based receiver is given.
2016 IEEE International Conference on the Science of Electrical Engineering (ICSEE), 2016
OFDM signal suffers from high Peak to Average Power Ratio (PAPR). This dictates the necessity to ... more OFDM signal suffers from high Peak to Average Power Ratio (PAPR). This dictates the necessity to drive the nonlinear power amplifier with high back-off, which leads to low power amplifier efficiency. In this paper we consider system that contains Iterative Clipping and Filtering (ICF) at the transmitter for PAPR reduction and modified iterative receiver (MIR) for demodulation. The MIR demodulate the distorted received signal. The distortions are created by the ICF and the nonlinear PA. The system architecture provides two main degrees of freedom given by the two back-offs: BO1 for ICF and BO2 for the power amplifier. We suggest to exploit these degrees of freedom in order to optimize the system performance expressed by a triplet: power efficiency (PE), adjacent channel power ratio (ACPR) and symbol error rate (SER). The optimal pair [BO1 BO2] depends on the priority among ACPR, SER and PE. Once the priority is determined, the optimal pair [BO1 BO2] that optimizes the system performa...
A method of retrieval of a multitone corrupted by a strong wide-band FM interference is presented... more A method of retrieval of a multitone corrupted by a strong wide-band FM interference is presented. The input mixture is transformed into a new time domain, resulting in a concentration of the FM interference around a chosen frequency; this interference is then rejected by a constrained notch filter with a fixed notch point. Time warping is implemented through nonequally spaced sampling. The proposed method provides results superior to those of conventional adaptive processing, which fails to track the parameters of an FM interference with significantly large frequency deviations.
1996 8th European Signal Processing Conference (EUSIPCO 1996), 1996
The spectral subtraction approach has become almost standard in speech enhancement because it is ... more The spectral subtraction approach has become almost standard in speech enhancement because it is relatively easy to understand and implement. The major drawback of the spectral subtraction method is that it leaves residual noise with annoying noticeable tonal characteristics referred to as musical noise. For low SNR the perceived effect of the "musical noise" is close to that of the additive noise. In the present work we propose to reduce the musical noise by applying the output of a standard spectral subtractor to a constrained high order notch filter which suppresses the "musical noise". The filtration process distorts the speech signal. It is possible to reduce the level of distortion if the speech signal is preprocessed properly before it is contaminated by the noise. It will be demonstrated that the proposed method is superior to the standard spectral subtraction specially for low SNR. A comprehensive listening test indicated that for segmental SNR= −12dB, 7...
Uploads
Papers by Dov Wulich