Nahi Kandil - Academia.edu (original) (raw)

Papers by Nahi Kandil

2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting

This letter explores the relation between the number of modes in a lossy waveguide environment an... more This letter explores the relation between the number of modes in a lossy waveguide environment and Multiple Input Multiple Output antenna array size. We estimated the number of modes in the underground mine tunnel theoretically by using a ray tracing model. The presented formula can be used for determining the number of modes which can act as a propagating channel for MIMO in a straight mine tunnel.

Human Centred Intelligent Systems, 2020

This paper reports a comparative study of the most significant 4G mobile network open-source plat... more This paper reports a comparative study of the most significant 4G mobile network open-source platforms, namely: OAI and srsLTE. Moreover, this study includes 4G Amarisoft software, one of the promising commercial alternatives. The three alternatives were evaluated in the indoor environment of the university building in order to enhance LTE signal propagation and extend the capacity of preexisting WIFI solution. The carried out experimental measurements are compared and analyzed according to the Quality of Service (QoS) link and to the use of processing and/or computation resources. The results demonstrated that the commercial one outperforms the open-source alternatives, although the performance of the OAI solution appears to be fairly similar to the Amarisoft one.

2016 IEEE International Symposium on Antennas and Propagation (APSURSI), 2016

In wireless fading channels, the path-loss exponent (PLE) is one of the most fundamental paramete... more In wireless fading channels, the path-loss exponent (PLE) is one of the most fundamental parameters to characterize the channel propagation. It has an important impact on the received signal strength (RSS)-based localization in wireless sensor networks (WSN). On the other hand, the communication range of a sensor in a WSN depends on the transmission power and on the environment (outdoor or indoor). Hence, the propagation conditions have a great influence on the connectivity between sensors in WSN, especially in complex environments. Nevertheless, most approaches used to estimate the PLE require some information of the wireless network such as RSS at some nodes, or some external information such as Global Positioning System. However, this information might be sometimes unreliable or difficult to obtain. In this paper, we propose a method to estimate the PLE based on the connectivity between sensors deployed in a determined area.

2018 Sixth International Conference on Digital Information, Networking, and Wireless Communications (DINWC), 2018

In this paper, we present a time delay analysis for indoor localization based on time difference ... more In this paper, we present a time delay analysis for indoor localization based on time difference of arrival (TDOA) algorithm, where we have performed both simulative and practical experiment together. Besides, we introduce the different channel parameter effects for line of sight (LOS) and non-line of sight (NLOS) scenario in indoor environment. This time delay analysis can be useful to understand the behavior of indoor channels and to choose the perfect technology for indoor localization. Results show remarkable effects of delay in TDOA localization in such environment. In addition, these results give enough information for improving localization techniques.

2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, 2020

Multistage Voltage Doubler Rectifiers (MVDR) are known to increase the level of the output DC vol... more Multistage Voltage Doubler Rectifiers (MVDR) are known to increase the level of the output DC voltage of a Rectifying Antenna (rectenna). However, the RF / DC conversion efficiency is very sensitive to the internal electrical characteristics of the used diode. This paper then proposes an analysis of the performance of an MVDR according to the features of the Schottky diode. A Rectenna Figure of Merit (RFoM), considering the DC output voltage as well as the RF / DC conversion efficiency, is defined to analyze MVDRs with up to ten stages. This analysis makes it possible to obtain that the most effective rectifier diode differs depending on the number of stages of the rectifier. More specifically, it is observed that, for two stages, the most efficient diode is the Schottky diode HSMS2820. For MVDR with more than five stages, the SMS 7630 diode is more suitable for low input power levels (less than 5 dBm). It is also observed that, for power levels higher than 5 dBm, the HSMS2850 diode offers the best compromise in terms of output DC voltage and conversion efficiency.

2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, 2020

Radiofrequency waves are increasingly seen as a promising solution for powering Wireless Sensor N... more Radiofrequency waves are increasingly seen as a promising solution for powering Wireless Sensor Nodes (WSN) dedicated to the Internet of Things (IoT) applications. However, by considering the RF source as a WSN power solution, Battery Recharging Time (BRT) becomes a critical performance metric, especially when the Quality of Service (QoS) is a requirement. In the literature, very few works propose an analysis of BRT based on an RF Energy Harvesting system. In this paper, the characterization of the BRT as a function of the harvestable power is analyzed, and modeling of the BRT is then proposed. The results are based on the ambient power density level measured in a building. It is obtained that the BRT undergoes as the received ambient power, a large scale fading effect shadowing more specifically the lognormal Shadowing.

2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2018

Energy-efficiency in Wireless Sensor Networks (WSNs) has been regarded as the core issue for desi... more Energy-efficiency in Wireless Sensor Networks (WSNs) has been regarded as the core issue for designing any communication protocol. Sensor networks consist of limited battery-powered nodes and recharging or replacing is not practical being deployed in harsh environments like underground mines. So designing of WSNs should be concentrated on energy efficiency. Clustering technique is used very effectively to achieve scaling up and power saving in WSNs. It allows hierarchical structures to be built on the nodes and enables the more efficient use of scares resources. In this work, we have proposed a hybrid clustering scheme which able to meet energy constraints of WSNs. It allows data transmission from sensor nodes to the sink with reasonable consumption of energy.

2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2017

We propose a novel range-free localization algorithm for wireless sensor networks (WSN)s that is ... more We propose a novel range-free localization algorithm for wireless sensor networks (WSN)s that is robust against the anisotropic signal attenuation induced by fading, shadowing, and interference, etc., present in any wireless channel, and hereby develop a new distance estimation (DE) approach able to efficiently derive distances' estimates in closed form. Exploiting artificial neural networks (ANN)s, we also develop a power-efficient DE correction mechanism that properly accounts for anisotropic signal attenuation. Simulation results show that the proposed algorithm significantly outperforms most representative range-free localization algorithms, not only in accuracy, but also in robustness against anisotropic attenuation.

2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, 2019

Given the low density of the surrounding RF powers, the rectifying stage is the one on which the ... more Given the low density of the surrounding RF powers, the rectifying stage is the one on which the designers of the rectenna (rectifying antenna) carry the most attention. Rectifier circuits must be of high efficiency to have usable DC output powers. Since the conversion efficiency is directly related to the electrical parameters of the used rectifying diode, this paper proposes a comparative study of the RF/DC conversion efficiency of an RF rectifier for the commonly considered Schottky diodes. In addition to the electrical parameters of the used diode, the operating frequency, as well as the desired level of DC output voltage, are considered in the comparison. Five diodes manufactured by AVAGO (HSMS 2820, HSMS 2850, HSMS 2860) and two Skyworks diodes (SMS 7621 and SMS 7630) are treated in this paper. This study will then provide designers with useful information in the selection of the rectifier diode and associated design parameters.

Applied Sciences, 2020

The vibrations, due to their abundance in most industrial processes, constitute an attractive sol... more The vibrations, due to their abundance in most industrial processes, constitute an attractive solution for the power supply of Industrial Wireless Sensor (IWS). However, the amount of energy that can be harvested presents numerous fluctuations due to the engines’ different operating modes (overload, full load, or even operation without charge). Most designs do not incorporate this fluctuation in the definition of the specifications of the autonomous IWS. This paper then presents a design method to ensure the node’s energy autonomy while maximizing its Quality of Service (QoS). To precisely define the specifications of the IWS, vibration measurements were carried out at its location for one month. The recorded data was used to propose a new Predictor of the Harvestable Energy from Vibrations (PHEV). A comparative evaluation of the proposed PHEV performances with a state-of-the-art predictor is carried out. The results obtained show that the PHEV makes it possible to minimize the Root...

2018 Sixth International Conference on Digital Information, Networking, and Wireless Communications (DINWC), 2018

Energy efficiency is considered as the key issue in the design of Wireless Sensor Networks (WSNs)... more Energy efficiency is considered as the key issue in the design of Wireless Sensor Networks (WSNs). Saving energy often introduces additional network delay, which is not desirable in case of critical application. For such application, the system should be time responsive. Most of the recent scenarios have not introduced any management of critical applications to their works in order to achieve energy efficiency. However, managing the critical data along with non-critical data is not often good for energy efficiency. Clustering is one technique that used very effectively to achieve scaling up and power saving in WSNs. In this work, we proposed a clustering scheme that able to manage critical or delay-sensitive applications with other best effort applications and meets both delay and energy constraints.

2018 Sixth International Conference on Digital Information, Networking, and Wireless Communications (DINWC), 2018

This paper evaluated the performance of ultrawide band (UWB) technology for underground localizat... more This paper evaluated the performance of ultrawide band (UWB) technology for underground localization. As UWB is featured up with several advantages, this performance analysis can be exploited for designing a better adaptive communication system in harsh environments like underground mine. Besides, we have used two way ranging (TWR) technique with UWB for ranging. To this end, we have performed measurements using TWR UWB mechanism in underground mine and compared the distances with reference distance. The results were promising for UWB technology in the underground mine along with shows the effectivity with TWR ranging technique in harsh environment.

ITM Web of Conferences, 2019

The aim of this paper is to prove theoretically by using waveguide and geometrical optical models... more The aim of this paper is to prove theoretically by using waveguide and geometrical optical models that increasing MIMO array elements at the transmitter and receiver will have a limit on capacity where the equivalent spatial subchannels can be limited by the number of allowable modes.

ITM Web of Conferences, 2019

In this article we present a localization technique based on received signal strength (RSS) combi... more In this article we present a localization technique based on received signal strength (RSS) combined with the gradient descent optimization method. The goal of this article is to show the importance of gradient descent in localization domain over the trilateration technique, and that by reducing the number of needed anchor nodes. Furthermore, we demonstrate the effect of the initialization technique on the localization accuracy. Results have shown that the selection of the initialization type (4 types of initialization were tested) has an efficient impact on the accuracy of the target sensors location estimation.

IEEE Transactions on Communications, 2016

To localize the wireless sensor networks nodes, only the hop-based information (i.e., hops' numbe... more To localize the wireless sensor networks nodes, only the hop-based information (i.e., hops' number, average hop size, and so on) has been, so far, exploited by range-free techniques, with poor-accuracy, however. In this paper, we show that localization accuracy may greatly benefit from joint exploitation, at no cost, of the information already provided by the forwarding nodes (i.e., relays) between each anchor (i.e., position aware) and sensor nodes pair. As such, we develop a novel range-free localization algorithm, derive its average location estimation error (LEE) in closed-form, and compare it in LEE performance with the best representative algorithms in the literature. We show that the proposed algorithm outperforms them in accuracy. In contrast to the latter, we further prove that it is able to achieve an LEE average and variance of about 0 when the number of sensors is large enough, thereby achieving an unprecedented accuracy performance among range-free techniques.

2016 International Wireless Communications and Mobile Computing Conference (IWCMC), 2016

In this paper, we develop a novel optimal anchors placement strategy tailored for anisotropic WSN... more In this paper, we develop a novel optimal anchors placement strategy tailored for anisotropic WSNs. By resorting to the well-known particle swarm optimization (PSO), we derive the optimal anchors' positions that minimize the average location estimation error (LEE). We show that our placement strategy provides substantial accuracy gains if used instead of the conventional ones and that it is able to reduce not only the average LEE but also the LEE itself and, hence, guarantees high accuracy for any WSN configuration.

2016 IEEE Wireless Communications and Networking Conference, 2016

In this paper, we propose a novel range-free localization algorithm tailored for mobile ad hoc ne... more In this paper, we propose a novel range-free localization algorithm tailored for mobile ad hoc networks (MANET)s. In contrast to most existing range-free techniques, we take into account the nodes mobility and hence enable the nodes to estimate their positions using solely their locally-available information, thereby avoiding any unnecessary costs in overhead and power that would have been incurred if information exchange between nodes were required. Furthermore, we show that the proposed algorithm outperforms in accuracy the best representative rangefree algorithms. In contrast to the latter, it is able to compensate the nodes mobility effects when the nodes' speeds are moderate.

IEEE Wireless Communications Letters, 2016

We propose a novel range-free localization algorithm for wireless sensor networks that is robust ... more We propose a novel range-free localization algorithm for wireless sensor networks that is robust against the anisotropic signal attenuation induced by fading, shadowing, interference, etc., present in any wireless channel, and hereby, develop a new distance estimation (DE) approach able to efficiently derive distances' estimates in closed form. Exploiting artificial neural networks, we also develop a power-efficient DE correction mechanism that properly accounts for anisotropic signal attenuation. Simulation results show that the proposed algorithm significantly outperforms most representative range-free localization algorithms, not only in accuracy but also in robustness against anisotropic attenuation. Index Terms-Localization, wireless sensor networks (WSNs), artificial neural networks (ANNs), radio propagation pattern (RPP), anisotropic signal attenuation, cost and power efficiencies, robustness. I. INTRODUCTION L OCALIZATION is crucial for many WSN applications such as environment monitoring, disaster relief, and target tracking [1]. So far, several localization algorithms have been proposed in the literature. These algorithms can be roughly classified into two categories: range-based and rangefree [2]-[4]. To properly localize the regular or positionunaware node positions, range-based algorithms exploit the measurements of some specific received signals' characteristics such as the time of arrival (TOA), the angle of arrival (AOA), or the received signal strength (RSS). These signals are, in fact, transmitted by nodes aware of their positions called anchors (or landmarks). Although range-based algorithms are very accurate, in general, they are unsuitable for WSNs. Indeed, these algorithms require high power to ensure communication between anchors and regular nodes which are small battery-powered units. Furthermore, additional hardware is usually required at both anchors and regular nodes, thereby increasing the overall cost of the network. Unlike range-based algorithms, range-free algorithms, which rely on the network connectivity to estimate the regular node positions, are more power-efficient and do not require any additional hardware and, hence, are suitable for WSNs. Due to their practical

Globecom '00 - IEEE. Global Telecommunications Conference. Conference Record (Cat. No.00CH37137)

Abstmct-Use of coherent modulation for the uplink of wireless CDMA systems requires pilot signals... more Abstmct-Use of coherent modulation for the uplink of wireless CDMA systems requires pilot signals which contribute t o the interference seen by other users. In previous work we showed that blind array-receivers outperform pilot-channel assisted array-receivers in capacity for various operating conditions. These array-receivers avoid additional interference due t o pilot signals and achieve better channel identification using relatively stronger data signals. However, for BPSK signals they identify the channel within a sign ambiguity and require differential modulation and decoding of coherently detected bits. In this contribution we implement coherent modulation and detection and further increase the advantage of this blind channel identiflcation scheme by introducing a new pilot called "pilotsign". This pilot simply allows resolution of the channel sign ambiguity after its estimation by long-term averaging of the pilot-channel combiner output. Analysis indicates that the resulting pilot-sign assisted array-receiver requires very weak pilot power ratios, in the range of a fraction of a percent, and allows very signiflcant pilot power savings and large capacity gains compared t o pilot-channel arrayreceivers.

2016 IEEE Wireless Communications and Networking Conference, 2016

To localize multi-hop wireless sensor networks (WSN) nodes, only the hop-based information (i.e.,... more To localize multi-hop wireless sensor networks (WSN) nodes, only the hop-based information (i.e., hops' number, average hop size, etc.) have been so far exploited by rangefree techniques, with poor-accuracy, however. In this paper, we show that localization accuracy may greatly benefit from joint exploitation, at no cost, of the information already provided by the forwarding nodes between each anchor (i.e., positionaware) and sensor nodes pair. As such, we develop a novel rangefree localization algorithm, derive its average location estimation error (LEE) in closed-form, and compare it in LEE performance with the best representative algorithms in the literature. We show that the proposed algorithm outperforms in accuracy all its counterparts. In contrast to the latter, we further prove that it is able to achieve a LEE average and variance of about 0 when the number of sensors is large enough, thereby achieving an unprecedented accuracy performance among rangefree techniques.

2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting

This letter explores the relation between the number of modes in a lossy waveguide environment an... more This letter explores the relation between the number of modes in a lossy waveguide environment and Multiple Input Multiple Output antenna array size. We estimated the number of modes in the underground mine tunnel theoretically by using a ray tracing model. The presented formula can be used for determining the number of modes which can act as a propagating channel for MIMO in a straight mine tunnel.

Human Centred Intelligent Systems, 2020

This paper reports a comparative study of the most significant 4G mobile network open-source plat... more This paper reports a comparative study of the most significant 4G mobile network open-source platforms, namely: OAI and srsLTE. Moreover, this study includes 4G Amarisoft software, one of the promising commercial alternatives. The three alternatives were evaluated in the indoor environment of the university building in order to enhance LTE signal propagation and extend the capacity of preexisting WIFI solution. The carried out experimental measurements are compared and analyzed according to the Quality of Service (QoS) link and to the use of processing and/or computation resources. The results demonstrated that the commercial one outperforms the open-source alternatives, although the performance of the OAI solution appears to be fairly similar to the Amarisoft one.

2016 IEEE International Symposium on Antennas and Propagation (APSURSI), 2016

In wireless fading channels, the path-loss exponent (PLE) is one of the most fundamental paramete... more In wireless fading channels, the path-loss exponent (PLE) is one of the most fundamental parameters to characterize the channel propagation. It has an important impact on the received signal strength (RSS)-based localization in wireless sensor networks (WSN). On the other hand, the communication range of a sensor in a WSN depends on the transmission power and on the environment (outdoor or indoor). Hence, the propagation conditions have a great influence on the connectivity between sensors in WSN, especially in complex environments. Nevertheless, most approaches used to estimate the PLE require some information of the wireless network such as RSS at some nodes, or some external information such as Global Positioning System. However, this information might be sometimes unreliable or difficult to obtain. In this paper, we propose a method to estimate the PLE based on the connectivity between sensors deployed in a determined area.

2018 Sixth International Conference on Digital Information, Networking, and Wireless Communications (DINWC), 2018

In this paper, we present a time delay analysis for indoor localization based on time difference ... more In this paper, we present a time delay analysis for indoor localization based on time difference of arrival (TDOA) algorithm, where we have performed both simulative and practical experiment together. Besides, we introduce the different channel parameter effects for line of sight (LOS) and non-line of sight (NLOS) scenario in indoor environment. This time delay analysis can be useful to understand the behavior of indoor channels and to choose the perfect technology for indoor localization. Results show remarkable effects of delay in TDOA localization in such environment. In addition, these results give enough information for improving localization techniques.

2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, 2020

Multistage Voltage Doubler Rectifiers (MVDR) are known to increase the level of the output DC vol... more Multistage Voltage Doubler Rectifiers (MVDR) are known to increase the level of the output DC voltage of a Rectifying Antenna (rectenna). However, the RF / DC conversion efficiency is very sensitive to the internal electrical characteristics of the used diode. This paper then proposes an analysis of the performance of an MVDR according to the features of the Schottky diode. A Rectenna Figure of Merit (RFoM), considering the DC output voltage as well as the RF / DC conversion efficiency, is defined to analyze MVDRs with up to ten stages. This analysis makes it possible to obtain that the most effective rectifier diode differs depending on the number of stages of the rectifier. More specifically, it is observed that, for two stages, the most efficient diode is the Schottky diode HSMS2820. For MVDR with more than five stages, the SMS 7630 diode is more suitable for low input power levels (less than 5 dBm). It is also observed that, for power levels higher than 5 dBm, the HSMS2850 diode offers the best compromise in terms of output DC voltage and conversion efficiency.

2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, 2020

Radiofrequency waves are increasingly seen as a promising solution for powering Wireless Sensor N... more Radiofrequency waves are increasingly seen as a promising solution for powering Wireless Sensor Nodes (WSN) dedicated to the Internet of Things (IoT) applications. However, by considering the RF source as a WSN power solution, Battery Recharging Time (BRT) becomes a critical performance metric, especially when the Quality of Service (QoS) is a requirement. In the literature, very few works propose an analysis of BRT based on an RF Energy Harvesting system. In this paper, the characterization of the BRT as a function of the harvestable power is analyzed, and modeling of the BRT is then proposed. The results are based on the ambient power density level measured in a building. It is obtained that the BRT undergoes as the received ambient power, a large scale fading effect shadowing more specifically the lognormal Shadowing.

2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2018

Energy-efficiency in Wireless Sensor Networks (WSNs) has been regarded as the core issue for desi... more Energy-efficiency in Wireless Sensor Networks (WSNs) has been regarded as the core issue for designing any communication protocol. Sensor networks consist of limited battery-powered nodes and recharging or replacing is not practical being deployed in harsh environments like underground mines. So designing of WSNs should be concentrated on energy efficiency. Clustering technique is used very effectively to achieve scaling up and power saving in WSNs. It allows hierarchical structures to be built on the nodes and enables the more efficient use of scares resources. In this work, we have proposed a hybrid clustering scheme which able to meet energy constraints of WSNs. It allows data transmission from sensor nodes to the sink with reasonable consumption of energy.

2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2017

We propose a novel range-free localization algorithm for wireless sensor networks (WSN)s that is ... more We propose a novel range-free localization algorithm for wireless sensor networks (WSN)s that is robust against the anisotropic signal attenuation induced by fading, shadowing, and interference, etc., present in any wireless channel, and hereby develop a new distance estimation (DE) approach able to efficiently derive distances' estimates in closed form. Exploiting artificial neural networks (ANN)s, we also develop a power-efficient DE correction mechanism that properly accounts for anisotropic signal attenuation. Simulation results show that the proposed algorithm significantly outperforms most representative range-free localization algorithms, not only in accuracy, but also in robustness against anisotropic attenuation.

2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, 2019

Given the low density of the surrounding RF powers, the rectifying stage is the one on which the ... more Given the low density of the surrounding RF powers, the rectifying stage is the one on which the designers of the rectenna (rectifying antenna) carry the most attention. Rectifier circuits must be of high efficiency to have usable DC output powers. Since the conversion efficiency is directly related to the electrical parameters of the used rectifying diode, this paper proposes a comparative study of the RF/DC conversion efficiency of an RF rectifier for the commonly considered Schottky diodes. In addition to the electrical parameters of the used diode, the operating frequency, as well as the desired level of DC output voltage, are considered in the comparison. Five diodes manufactured by AVAGO (HSMS 2820, HSMS 2850, HSMS 2860) and two Skyworks diodes (SMS 7621 and SMS 7630) are treated in this paper. This study will then provide designers with useful information in the selection of the rectifier diode and associated design parameters.

Applied Sciences, 2020

The vibrations, due to their abundance in most industrial processes, constitute an attractive sol... more The vibrations, due to their abundance in most industrial processes, constitute an attractive solution for the power supply of Industrial Wireless Sensor (IWS). However, the amount of energy that can be harvested presents numerous fluctuations due to the engines’ different operating modes (overload, full load, or even operation without charge). Most designs do not incorporate this fluctuation in the definition of the specifications of the autonomous IWS. This paper then presents a design method to ensure the node’s energy autonomy while maximizing its Quality of Service (QoS). To precisely define the specifications of the IWS, vibration measurements were carried out at its location for one month. The recorded data was used to propose a new Predictor of the Harvestable Energy from Vibrations (PHEV). A comparative evaluation of the proposed PHEV performances with a state-of-the-art predictor is carried out. The results obtained show that the PHEV makes it possible to minimize the Root...

2018 Sixth International Conference on Digital Information, Networking, and Wireless Communications (DINWC), 2018

Energy efficiency is considered as the key issue in the design of Wireless Sensor Networks (WSNs)... more Energy efficiency is considered as the key issue in the design of Wireless Sensor Networks (WSNs). Saving energy often introduces additional network delay, which is not desirable in case of critical application. For such application, the system should be time responsive. Most of the recent scenarios have not introduced any management of critical applications to their works in order to achieve energy efficiency. However, managing the critical data along with non-critical data is not often good for energy efficiency. Clustering is one technique that used very effectively to achieve scaling up and power saving in WSNs. In this work, we proposed a clustering scheme that able to manage critical or delay-sensitive applications with other best effort applications and meets both delay and energy constraints.

2018 Sixth International Conference on Digital Information, Networking, and Wireless Communications (DINWC), 2018

This paper evaluated the performance of ultrawide band (UWB) technology for underground localizat... more This paper evaluated the performance of ultrawide band (UWB) technology for underground localization. As UWB is featured up with several advantages, this performance analysis can be exploited for designing a better adaptive communication system in harsh environments like underground mine. Besides, we have used two way ranging (TWR) technique with UWB for ranging. To this end, we have performed measurements using TWR UWB mechanism in underground mine and compared the distances with reference distance. The results were promising for UWB technology in the underground mine along with shows the effectivity with TWR ranging technique in harsh environment.

ITM Web of Conferences, 2019

The aim of this paper is to prove theoretically by using waveguide and geometrical optical models... more The aim of this paper is to prove theoretically by using waveguide and geometrical optical models that increasing MIMO array elements at the transmitter and receiver will have a limit on capacity where the equivalent spatial subchannels can be limited by the number of allowable modes.

ITM Web of Conferences, 2019

In this article we present a localization technique based on received signal strength (RSS) combi... more In this article we present a localization technique based on received signal strength (RSS) combined with the gradient descent optimization method. The goal of this article is to show the importance of gradient descent in localization domain over the trilateration technique, and that by reducing the number of needed anchor nodes. Furthermore, we demonstrate the effect of the initialization technique on the localization accuracy. Results have shown that the selection of the initialization type (4 types of initialization were tested) has an efficient impact on the accuracy of the target sensors location estimation.

IEEE Transactions on Communications, 2016

To localize the wireless sensor networks nodes, only the hop-based information (i.e., hops' numbe... more To localize the wireless sensor networks nodes, only the hop-based information (i.e., hops' number, average hop size, and so on) has been, so far, exploited by range-free techniques, with poor-accuracy, however. In this paper, we show that localization accuracy may greatly benefit from joint exploitation, at no cost, of the information already provided by the forwarding nodes (i.e., relays) between each anchor (i.e., position aware) and sensor nodes pair. As such, we develop a novel range-free localization algorithm, derive its average location estimation error (LEE) in closed-form, and compare it in LEE performance with the best representative algorithms in the literature. We show that the proposed algorithm outperforms them in accuracy. In contrast to the latter, we further prove that it is able to achieve an LEE average and variance of about 0 when the number of sensors is large enough, thereby achieving an unprecedented accuracy performance among range-free techniques.

2016 International Wireless Communications and Mobile Computing Conference (IWCMC), 2016

In this paper, we develop a novel optimal anchors placement strategy tailored for anisotropic WSN... more In this paper, we develop a novel optimal anchors placement strategy tailored for anisotropic WSNs. By resorting to the well-known particle swarm optimization (PSO), we derive the optimal anchors' positions that minimize the average location estimation error (LEE). We show that our placement strategy provides substantial accuracy gains if used instead of the conventional ones and that it is able to reduce not only the average LEE but also the LEE itself and, hence, guarantees high accuracy for any WSN configuration.

2016 IEEE Wireless Communications and Networking Conference, 2016

In this paper, we propose a novel range-free localization algorithm tailored for mobile ad hoc ne... more In this paper, we propose a novel range-free localization algorithm tailored for mobile ad hoc networks (MANET)s. In contrast to most existing range-free techniques, we take into account the nodes mobility and hence enable the nodes to estimate their positions using solely their locally-available information, thereby avoiding any unnecessary costs in overhead and power that would have been incurred if information exchange between nodes were required. Furthermore, we show that the proposed algorithm outperforms in accuracy the best representative rangefree algorithms. In contrast to the latter, it is able to compensate the nodes mobility effects when the nodes' speeds are moderate.

IEEE Wireless Communications Letters, 2016

We propose a novel range-free localization algorithm for wireless sensor networks that is robust ... more We propose a novel range-free localization algorithm for wireless sensor networks that is robust against the anisotropic signal attenuation induced by fading, shadowing, interference, etc., present in any wireless channel, and hereby, develop a new distance estimation (DE) approach able to efficiently derive distances' estimates in closed form. Exploiting artificial neural networks, we also develop a power-efficient DE correction mechanism that properly accounts for anisotropic signal attenuation. Simulation results show that the proposed algorithm significantly outperforms most representative range-free localization algorithms, not only in accuracy but also in robustness against anisotropic attenuation. Index Terms-Localization, wireless sensor networks (WSNs), artificial neural networks (ANNs), radio propagation pattern (RPP), anisotropic signal attenuation, cost and power efficiencies, robustness. I. INTRODUCTION L OCALIZATION is crucial for many WSN applications such as environment monitoring, disaster relief, and target tracking [1]. So far, several localization algorithms have been proposed in the literature. These algorithms can be roughly classified into two categories: range-based and rangefree [2]-[4]. To properly localize the regular or positionunaware node positions, range-based algorithms exploit the measurements of some specific received signals' characteristics such as the time of arrival (TOA), the angle of arrival (AOA), or the received signal strength (RSS). These signals are, in fact, transmitted by nodes aware of their positions called anchors (or landmarks). Although range-based algorithms are very accurate, in general, they are unsuitable for WSNs. Indeed, these algorithms require high power to ensure communication between anchors and regular nodes which are small battery-powered units. Furthermore, additional hardware is usually required at both anchors and regular nodes, thereby increasing the overall cost of the network. Unlike range-based algorithms, range-free algorithms, which rely on the network connectivity to estimate the regular node positions, are more power-efficient and do not require any additional hardware and, hence, are suitable for WSNs. Due to their practical

Globecom '00 - IEEE. Global Telecommunications Conference. Conference Record (Cat. No.00CH37137)

Abstmct-Use of coherent modulation for the uplink of wireless CDMA systems requires pilot signals... more Abstmct-Use of coherent modulation for the uplink of wireless CDMA systems requires pilot signals which contribute t o the interference seen by other users. In previous work we showed that blind array-receivers outperform pilot-channel assisted array-receivers in capacity for various operating conditions. These array-receivers avoid additional interference due t o pilot signals and achieve better channel identification using relatively stronger data signals. However, for BPSK signals they identify the channel within a sign ambiguity and require differential modulation and decoding of coherently detected bits. In this contribution we implement coherent modulation and detection and further increase the advantage of this blind channel identiflcation scheme by introducing a new pilot called "pilotsign". This pilot simply allows resolution of the channel sign ambiguity after its estimation by long-term averaging of the pilot-channel combiner output. Analysis indicates that the resulting pilot-sign assisted array-receiver requires very weak pilot power ratios, in the range of a fraction of a percent, and allows very signiflcant pilot power savings and large capacity gains compared t o pilot-channel arrayreceivers.

2016 IEEE Wireless Communications and Networking Conference, 2016

To localize multi-hop wireless sensor networks (WSN) nodes, only the hop-based information (i.e.,... more To localize multi-hop wireless sensor networks (WSN) nodes, only the hop-based information (i.e., hops' number, average hop size, etc.) have been so far exploited by rangefree techniques, with poor-accuracy, however. In this paper, we show that localization accuracy may greatly benefit from joint exploitation, at no cost, of the information already provided by the forwarding nodes between each anchor (i.e., positionaware) and sensor nodes pair. As such, we develop a novel rangefree localization algorithm, derive its average location estimation error (LEE) in closed-form, and compare it in LEE performance with the best representative algorithms in the literature. We show that the proposed algorithm outperforms in accuracy all its counterparts. In contrast to the latter, we further prove that it is able to achieve a LEE average and variance of about 0 when the number of sensors is large enough, thereby achieving an unprecedented accuracy performance among rangefree techniques.