Mohammad Omer - Academia.edu (original) (raw)

Papers by Mohammad Omer

2011 IEEE MTT-S International Microwave Symposium

Current and future generation radio transceivers have to share spectrum in increasingly tight fre... more Current and future generation radio transceivers have to share spectrum in increasingly tight frequency space. Front end nonlinearities create spectral expansion which leads to radio interference in adjacent bands. The problem is greatly exacerbated for full duplex receivers with closely spaced Tx/Rx channels. This work proposes a novel radio architecture that can take care of out of band (OOB) emissions and allow interference free full duplex radio operation using appropriate nonlinear interference cancellation schemes. We propose that nonlinear operation and the resulting spectral re-growth can be handled without incurring any extra analog hardware in the RF front- end. This is accomplished at the cost of extra base band DSP workload. We then demonstrate that such an operation is indeed possible by setting up an experiment with a commercial RF front end chipset. This can possibly lead to a wide range of applications where interference cancellation can either facilitate or enable radio co-existence in upcoming multi-radio transceivers.

The Journal of Contemporary Issues in Business and Government, 2021

Covid-19 is the most widely used pandemic in the sector, a leading product in digital and digital... more Covid-19 is the most widely used pandemic in the sector, a leading product in digital and digital media, including advertising, marketing and marketing. But Covid-1. The effect is mostly positive, not Covid-1. What other areas are about nations, human resources and tigers and so on. While the virus generates a lot of health insurance, social life, economic stability, jobs, etc. Intrastate, M., & Fuad, K. 2020, July stated that the list of customers and marketers. Covid-19 also leads to behavioral changes such as working remotely, spending a lot of time indoors, napping, learning recipes online, paying more attention to health and hygiene, prevention in Behavioral changes are particularly prevalent on digital platforms and digital content and create opportunities for marketers and brands to communicate digitally with customers more than ever. There has been an increase in social media engagement and the desire for digital content digital tools to sell many earning opportunities added...

Introduction 1 1.1 Introduction and motivation for research 1 1.2 Necessity for coexistence 2 1.3... more Introduction 1 1.1 Introduction and motivation for research 1 1.2 Necessity for coexistence 2 1.3 Radio coexistence 6 1.4 Organization of the thesis 8 CHAPTER 2 : Conventional RF Coexistence Methods and Tools 2.1 Radio front ends and nonlinear distortion 2.2 Modeling nonlinear components 12 2.3 Pre-distortion for transmitter linearization: 2.3.1 LUT based predistortion 14 2.3.2 A Polynomial predistortion architecture: 17 2.4 Design of a predistortion system 19 2.4.1 Design constraints with predistortion systems 2.4.2 An improved predistortion architecture 21 2.4.3 Predistortion system components and caveats 2.5 Conclusion v

Background and Purpose: Microstructure imaging with advanced diffusion MRI (dMRI) techniques have... more Background and Purpose: Microstructure imaging with advanced diffusion MRI (dMRI) techniques have shown increased sensitivity and specificity to microstructural changes in various disease and injury models. Oscillating gradient spin echo (OGSE) dMRI, implemented by varying the oscillating gradient frequency, and microscopic anisotropy (µA) dMRI, implemented via tensor valued diffusion encoding, may provide additional insight by increasing sensitivity to smaller spatial scales and disentangling fiber orientation dispersion from true microstructural changes, respectively. The aims of this study were to characterize the test-retest reproducibility of in vivo OGSE and µA dMRI metrics in the mouse brain at 9.4 Tesla and provide estimates of required sample sizes for future investigations. Methods: Eight adult C57Bl/6 mice were scanned twice (5 days apart). Each imaging session consisted of multifrequency OGSE and µA dMRI protocols. Metrics investigated included µA, isotropic and anisotro...

South Asian Journal of Management Sciences

Proceedings of the 6th International Conference on Information Systems Security and Privacy, 2020

IoT (Internet of Things) devices have grown exponentially in the last years, both in the sheer nu... more IoT (Internet of Things) devices have grown exponentially in the last years, both in the sheer number of devices and concerning areas of applications being introduced. Together with this rapid deve ...

International Journal of Surgery Open

Abstract Background One of the top worldwide health problems is overweight and obesity, Body weig... more Abstract Background One of the top worldwide health problems is overweight and obesity, Body weight gain over a number of years could be achieved through cumulative positive energy balances, which may be the result of habitual behaviors adopted through personal choice. Despite the increased in physical activity, the percentage of people who are overweight has increased, after decades-old efforts and awareness on the issue to nudge consumers towards healthier lifestyles through dietary guidelines, diet-related diseases are still on the rise. Is there potential variables need to be evaluated for any relation with gaining weight and obesity in the patient's life styles? Objectives Exploration of the possible factors in the life style of overweight and obese patients, resulting in weight gain. Patients and Methods A prospective randomized study including 440 overweight or obese patients from a total of 689 patients, who consulted for advice, diet and or drugs and various bariatric operations. This was conducted in the period of 5 years from January 2, 2012 to October 1, 2017. For the information collection, each patient was interviewed face-to-face, by three Surgical Board Trainees were interviewing patients face-to-face to fill an originally-designed questionnaire in English translated to the Kurdish language. The questionnaire was composed of demographic data, medical data, biological data, and potential factors of their overweight or obesity. A comparison was made between these patients in the conception of case matching to 446 patients who were of normal body weight, and a normal BMI. Results Most of the patients (females; n = 200, 86.95% and males; n = 167, 79.52%) in group A, while (females; n = 14, 5.90% and males; n = 21, 10.05%) were drinking water within 30 min after every meals, meanwhile (females; n = 202, 85.23%, and males; n = 173, 82.77%) from group B patients were drinking water 60 min after every meals. Nearly half of the patients have a Television in their kitchen/dining room (n = 239/440, 54.39%), however only (51.59%), (13.90%) of the patients from group A, and B respectively were watching TV while eating, A great number of the patients (Group A: n = 358, 81.36%) were operating their computers while eating, versus minority (n = 53, 11.88%), in Group B, and majority of the patients in group A were using their smart phones or making phone calls while eating (n = 390/440, 88.63%) versus small number (n = 49/460, 10.65%) in group B. Conclusion Excessive habitual usage of a cell phone, early drinking (within 30 min) of water or other liquids after meals may be the potential factors in the initiation of becoming overweight and obese. University students living in the areas where entertainments are not affordable for all, the only remaining entertainment is using cellphones for social media and communication may be more vulnerable to gain weight, overweight and obesity.

International journal of surgery (London, England), 2018

The increasing incidence of morbid obesity suggests that the quantity of bariatric surgical proce... more The increasing incidence of morbid obesity suggests that the quantity of bariatric surgical procedures will continue to multiply each year, many patients who have experienced massive weight loss are left with the dissatisfying consequences of loose and redundant skin, resulting in contour irregularities, an aesthetic and functional problem, and profound dissatisfaction with appearance, residual body image dissatisfaction, There is a subsequent increase in the number of patients seeking additional corrective procedures including abdominoplasty which considered as one of the most popular body-contouring procedures. Correcting skin excess, could improve all the corollaries, including body, and functional problems and gives profound satisfaction with appearance, it has shown to improve both psychological and social aspects of the patients' lives. Is there a gender difference in seeking body countering after bariatric surgery for weight loss? A longitudinal observational study includ...

International Journal of Microwave and Wireless Technologies, 2016

In building highly efficient transmitters of today, one is forced to sacrifice linearity for effi... more In building highly efficient transmitters of today, one is forced to sacrifice linearity for efficiency. Some of the highest power amplifier efficiency figures are reported by envelope tracking (ET) amplifiers. These amplifiers can generate strong higher-order harmonics, which can lead to interference with receivers operating at the harmonic frequencies. Using non-linear interference cancellation, we can help to remove the interference being caused in those receivers. This paper looks at the problem of modeling the third and second-order harmonic emission from an ET amplifier. It derives the non-linear kernel for estimating such interference. This kernel has been rigorously expanded to show its correlation with the various harmonics and its effectiveness in predicting the harmonic content. We then set up an envelope amplifier test-bench to capture harmonic signal content and cancel it using the derived kernel model. The experiment yields excellent agreement with theory and provides ...

2012 Ieee Radio Frequency Integrated Circuits Symposium, 2012

The evolution of efficiency in RF power amplifiers has been very gradual. Even today, they dissip... more The evolution of efficiency in RF power amplifiers has been very gradual. Even today, they dissipate a lot of energy as heat which reduces the efficiency and increases the noise level. This PA noise is generally attenuated down to the thermal noise floor of the receiver by using highly selective duplexers. High selectivity necessarily carries high insertion loss and hence the PA output power requirement further increases. In the next generation of radios, efforts are underway to substantially reduce duplexer size and selectivity specifications. This will lead to a significant increase in the PA noise falling into the receive band. This work looks at a new technique to mitigate this receive-band noise by means of a mixed signal architecture using analog and digital components. We demonstrate that the cancellation of this noise can be accomplished by the receiver, and SNR gains can be demonstrated using commercial RFICs.

The presence of carbon dioxide (CO2) in natural gas stream become a problem since it brought nega... more The presence of carbon dioxide (CO2) in natural gas stream become a problem since it brought negative impact to the heating value of the natural gas, as well as causing corrosion to pipelines and hydrate formation problem. Recently the new kind of adsorbent has been discovered to have the high capacity for CO2 adsorption that includes Metal-Organic Framework (MOF), Covalent-Organic Framework (COF) and Covalent Organic Polymer (COPs). This research is concentrated to develop the COP-4 adsorbent using microwave reactor method. The main challenges in this research are the limitation information from literature regarding the COP synthesis using microwave reactor as well as longer time preparation by using conventional method. This method propose a faster synthesis method of COP-4 and theoretically will give higher yield and less reaction time. After synthesis, COP-4 sample undergo the characterization test included FTIR, TGA, SEM, XRD and BET. The results will be compared to the COP material developed using conventional method. Consequently, this study will contribute towards the development of sustainable CO2 removal technologies.

The 40th European Microwave Conference, 2010

Research toward high output power, high efficiency RF power amplifiers has been growing recently.... more Research toward high output power, high efficiency RF power amplifiers has been growing recently. Upconverting parametric power amplifiers (paramps) have been suggested as one possible solution to the problem of high linearity amplification of complex wideband multi-carrier modulation schemes. Investigation of distortion characteristics of paramps is crucial before its widespread adoption. This paper presents the results of modeling, characterization and feedback linearization of paramps. A single-carrier WCDMA signal was used to derive the instantaneous complex gain function, which was then used to fit a behavioral model. It was found that the distortion is dominated by AM/PM distortion, but that AM/AM (gain compression), and long-term memory effects are also present. The Ghorbani model was used to obtain the best fit memoryless model for the paramp. Excellent agreement was observed between the measured gain function and the Ghorbani model for three different pump power levels. Memoryless digital predistortion was used to linearize the paramp, and a modest ACLR reduction of 10dB was obtained.

2013 Ieee Mtt S International Microwave Symposium Digest, Jun 2, 2013

In building highly efficient transmitters of today, one is forced to sacrifice linearity for effi... more In building highly efficient transmitters of today, one is forced to sacrifice linearity for efficiency. Some of the highest PA efficiency figures are reported by envelope tracking amplifiers. These amplifiers can generate strong higher order harmonics which can lead to interference with receivers operating at the harmonic frequencies. Using nonlinear interference cancellation, we can help to remove the interference being caused in those receivers. This paper looks at the problem of modeling the third harmonic emission from an envelope tracking amplifier. It derives the nonlinear kernel for estimating such interference. This kernel has been rigorously expanded to show its correlation with the third harmonic and its effectiveness in predicting the harmonic content. We then set up an envelope amplifier test-bench to capture the third harmonic and cancel it using the derived kernel model. The experiment yields excellent agreement with theory and provides a validation of the system and concept.

2011 IEEE MTT-S International Microwave Symposium

Current and future generation radio transceivers have to share spectrum in increasingly tight fre... more Current and future generation radio transceivers have to share spectrum in increasingly tight frequency space. Front end nonlinearities create spectral expansion which leads to radio interference in adjacent bands. The problem is greatly exacerbated for full duplex receivers with closely spaced Tx/Rx channels. This work proposes a novel radio architecture that can take care of out of band (OOB) emissions and allow interference free full duplex radio operation using appropriate nonlinear interference cancellation schemes. We propose that nonlinear operation and the resulting spectral re-growth can be handled without incurring any extra analog hardware in the RF front- end. This is accomplished at the cost of extra base band DSP workload. We then demonstrate that such an operation is indeed possible by setting up an experiment with a commercial RF front end chipset. This can possibly lead to a wide range of applications where interference cancellation can either facilitate or enable radio co-existence in upcoming multi-radio transceivers.

The Journal of Contemporary Issues in Business and Government, 2021

Covid-19 is the most widely used pandemic in the sector, a leading product in digital and digital... more Covid-19 is the most widely used pandemic in the sector, a leading product in digital and digital media, including advertising, marketing and marketing. But Covid-1. The effect is mostly positive, not Covid-1. What other areas are about nations, human resources and tigers and so on. While the virus generates a lot of health insurance, social life, economic stability, jobs, etc. Intrastate, M., & Fuad, K. 2020, July stated that the list of customers and marketers. Covid-19 also leads to behavioral changes such as working remotely, spending a lot of time indoors, napping, learning recipes online, paying more attention to health and hygiene, prevention in Behavioral changes are particularly prevalent on digital platforms and digital content and create opportunities for marketers and brands to communicate digitally with customers more than ever. There has been an increase in social media engagement and the desire for digital content digital tools to sell many earning opportunities added...

Introduction 1 1.1 Introduction and motivation for research 1 1.2 Necessity for coexistence 2 1.3... more Introduction 1 1.1 Introduction and motivation for research 1 1.2 Necessity for coexistence 2 1.3 Radio coexistence 6 1.4 Organization of the thesis 8 CHAPTER 2 : Conventional RF Coexistence Methods and Tools 2.1 Radio front ends and nonlinear distortion 2.2 Modeling nonlinear components 12 2.3 Pre-distortion for transmitter linearization: 2.3.1 LUT based predistortion 14 2.3.2 A Polynomial predistortion architecture: 17 2.4 Design of a predistortion system 19 2.4.1 Design constraints with predistortion systems 2.4.2 An improved predistortion architecture 21 2.4.3 Predistortion system components and caveats 2.5 Conclusion v

Background and Purpose: Microstructure imaging with advanced diffusion MRI (dMRI) techniques have... more Background and Purpose: Microstructure imaging with advanced diffusion MRI (dMRI) techniques have shown increased sensitivity and specificity to microstructural changes in various disease and injury models. Oscillating gradient spin echo (OGSE) dMRI, implemented by varying the oscillating gradient frequency, and microscopic anisotropy (µA) dMRI, implemented via tensor valued diffusion encoding, may provide additional insight by increasing sensitivity to smaller spatial scales and disentangling fiber orientation dispersion from true microstructural changes, respectively. The aims of this study were to characterize the test-retest reproducibility of in vivo OGSE and µA dMRI metrics in the mouse brain at 9.4 Tesla and provide estimates of required sample sizes for future investigations. Methods: Eight adult C57Bl/6 mice were scanned twice (5 days apart). Each imaging session consisted of multifrequency OGSE and µA dMRI protocols. Metrics investigated included µA, isotropic and anisotro...

South Asian Journal of Management Sciences

Proceedings of the 6th International Conference on Information Systems Security and Privacy, 2020

IoT (Internet of Things) devices have grown exponentially in the last years, both in the sheer nu... more IoT (Internet of Things) devices have grown exponentially in the last years, both in the sheer number of devices and concerning areas of applications being introduced. Together with this rapid deve ...

International Journal of Surgery Open

Abstract Background One of the top worldwide health problems is overweight and obesity, Body weig... more Abstract Background One of the top worldwide health problems is overweight and obesity, Body weight gain over a number of years could be achieved through cumulative positive energy balances, which may be the result of habitual behaviors adopted through personal choice. Despite the increased in physical activity, the percentage of people who are overweight has increased, after decades-old efforts and awareness on the issue to nudge consumers towards healthier lifestyles through dietary guidelines, diet-related diseases are still on the rise. Is there potential variables need to be evaluated for any relation with gaining weight and obesity in the patient's life styles? Objectives Exploration of the possible factors in the life style of overweight and obese patients, resulting in weight gain. Patients and Methods A prospective randomized study including 440 overweight or obese patients from a total of 689 patients, who consulted for advice, diet and or drugs and various bariatric operations. This was conducted in the period of 5 years from January 2, 2012 to October 1, 2017. For the information collection, each patient was interviewed face-to-face, by three Surgical Board Trainees were interviewing patients face-to-face to fill an originally-designed questionnaire in English translated to the Kurdish language. The questionnaire was composed of demographic data, medical data, biological data, and potential factors of their overweight or obesity. A comparison was made between these patients in the conception of case matching to 446 patients who were of normal body weight, and a normal BMI. Results Most of the patients (females; n = 200, 86.95% and males; n = 167, 79.52%) in group A, while (females; n = 14, 5.90% and males; n = 21, 10.05%) were drinking water within 30 min after every meals, meanwhile (females; n = 202, 85.23%, and males; n = 173, 82.77%) from group B patients were drinking water 60 min after every meals. Nearly half of the patients have a Television in their kitchen/dining room (n = 239/440, 54.39%), however only (51.59%), (13.90%) of the patients from group A, and B respectively were watching TV while eating, A great number of the patients (Group A: n = 358, 81.36%) were operating their computers while eating, versus minority (n = 53, 11.88%), in Group B, and majority of the patients in group A were using their smart phones or making phone calls while eating (n = 390/440, 88.63%) versus small number (n = 49/460, 10.65%) in group B. Conclusion Excessive habitual usage of a cell phone, early drinking (within 30 min) of water or other liquids after meals may be the potential factors in the initiation of becoming overweight and obese. University students living in the areas where entertainments are not affordable for all, the only remaining entertainment is using cellphones for social media and communication may be more vulnerable to gain weight, overweight and obesity.

International journal of surgery (London, England), 2018

The increasing incidence of morbid obesity suggests that the quantity of bariatric surgical proce... more The increasing incidence of morbid obesity suggests that the quantity of bariatric surgical procedures will continue to multiply each year, many patients who have experienced massive weight loss are left with the dissatisfying consequences of loose and redundant skin, resulting in contour irregularities, an aesthetic and functional problem, and profound dissatisfaction with appearance, residual body image dissatisfaction, There is a subsequent increase in the number of patients seeking additional corrective procedures including abdominoplasty which considered as one of the most popular body-contouring procedures. Correcting skin excess, could improve all the corollaries, including body, and functional problems and gives profound satisfaction with appearance, it has shown to improve both psychological and social aspects of the patients' lives. Is there a gender difference in seeking body countering after bariatric surgery for weight loss? A longitudinal observational study includ...

International Journal of Microwave and Wireless Technologies, 2016

In building highly efficient transmitters of today, one is forced to sacrifice linearity for effi... more In building highly efficient transmitters of today, one is forced to sacrifice linearity for efficiency. Some of the highest power amplifier efficiency figures are reported by envelope tracking (ET) amplifiers. These amplifiers can generate strong higher-order harmonics, which can lead to interference with receivers operating at the harmonic frequencies. Using non-linear interference cancellation, we can help to remove the interference being caused in those receivers. This paper looks at the problem of modeling the third and second-order harmonic emission from an ET amplifier. It derives the non-linear kernel for estimating such interference. This kernel has been rigorously expanded to show its correlation with the various harmonics and its effectiveness in predicting the harmonic content. We then set up an envelope amplifier test-bench to capture harmonic signal content and cancel it using the derived kernel model. The experiment yields excellent agreement with theory and provides ...

2012 Ieee Radio Frequency Integrated Circuits Symposium, 2012

The evolution of efficiency in RF power amplifiers has been very gradual. Even today, they dissip... more The evolution of efficiency in RF power amplifiers has been very gradual. Even today, they dissipate a lot of energy as heat which reduces the efficiency and increases the noise level. This PA noise is generally attenuated down to the thermal noise floor of the receiver by using highly selective duplexers. High selectivity necessarily carries high insertion loss and hence the PA output power requirement further increases. In the next generation of radios, efforts are underway to substantially reduce duplexer size and selectivity specifications. This will lead to a significant increase in the PA noise falling into the receive band. This work looks at a new technique to mitigate this receive-band noise by means of a mixed signal architecture using analog and digital components. We demonstrate that the cancellation of this noise can be accomplished by the receiver, and SNR gains can be demonstrated using commercial RFICs.

The presence of carbon dioxide (CO2) in natural gas stream become a problem since it brought nega... more The presence of carbon dioxide (CO2) in natural gas stream become a problem since it brought negative impact to the heating value of the natural gas, as well as causing corrosion to pipelines and hydrate formation problem. Recently the new kind of adsorbent has been discovered to have the high capacity for CO2 adsorption that includes Metal-Organic Framework (MOF), Covalent-Organic Framework (COF) and Covalent Organic Polymer (COPs). This research is concentrated to develop the COP-4 adsorbent using microwave reactor method. The main challenges in this research are the limitation information from literature regarding the COP synthesis using microwave reactor as well as longer time preparation by using conventional method. This method propose a faster synthesis method of COP-4 and theoretically will give higher yield and less reaction time. After synthesis, COP-4 sample undergo the characterization test included FTIR, TGA, SEM, XRD and BET. The results will be compared to the COP material developed using conventional method. Consequently, this study will contribute towards the development of sustainable CO2 removal technologies.

The 40th European Microwave Conference, 2010

Research toward high output power, high efficiency RF power amplifiers has been growing recently.... more Research toward high output power, high efficiency RF power amplifiers has been growing recently. Upconverting parametric power amplifiers (paramps) have been suggested as one possible solution to the problem of high linearity amplification of complex wideband multi-carrier modulation schemes. Investigation of distortion characteristics of paramps is crucial before its widespread adoption. This paper presents the results of modeling, characterization and feedback linearization of paramps. A single-carrier WCDMA signal was used to derive the instantaneous complex gain function, which was then used to fit a behavioral model. It was found that the distortion is dominated by AM/PM distortion, but that AM/AM (gain compression), and long-term memory effects are also present. The Ghorbani model was used to obtain the best fit memoryless model for the paramp. Excellent agreement was observed between the measured gain function and the Ghorbani model for three different pump power levels. Memoryless digital predistortion was used to linearize the paramp, and a modest ACLR reduction of 10dB was obtained.

2013 Ieee Mtt S International Microwave Symposium Digest, Jun 2, 2013

In building highly efficient transmitters of today, one is forced to sacrifice linearity for effi... more In building highly efficient transmitters of today, one is forced to sacrifice linearity for efficiency. Some of the highest PA efficiency figures are reported by envelope tracking amplifiers. These amplifiers can generate strong higher order harmonics which can lead to interference with receivers operating at the harmonic frequencies. Using nonlinear interference cancellation, we can help to remove the interference being caused in those receivers. This paper looks at the problem of modeling the third harmonic emission from an envelope tracking amplifier. It derives the nonlinear kernel for estimating such interference. This kernel has been rigorously expanded to show its correlation with the third harmonic and its effectiveness in predicting the harmonic content. We then set up an envelope amplifier test-bench to capture the third harmonic and cancel it using the derived kernel model. The experiment yields excellent agreement with theory and provides a validation of the system and concept.