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Mohamed S. Abdallah
Department of Electronics Engineering, School of Electronics Engineering, Chungbuk National University, Cheongju 371763, Korea

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Journal article
Published: 04 February 2021 in Electronics
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IEEE 1609/802.11p standard obligates each vehicle to broadcast a periodic basic safety message (BSM). The BSM message comprises a positional and kinematic information of a transmitting vehicle. It also contains emergency information that is to be delivered to all the target receivers. In broadcast communication, however, existing carrier sense multiple access (CSMA) medium access control (MAC) protocol cannot guarantee a high reliability as it suffers from two chronic problems, namely, access collision and hidden terminal interference. To resolve these problems of CSMA MAC, we propose a novel enhancement algorithm called a neighbor association-based MAC (NA-MAC) protocol. NA-MAC utilizes a time division multiple access (TDMA) to distribute channel resource into short time-intervals called slots. Each slot is further divided into three parts to conduct channel sensing, slot acquisition, and data transmission. To avoid a duplicate slot allocation among multiple vehicles, NA-MAC introduces a three-way handshake process during slot acquisition. Our simulation results revealed that NA-MAC improved packet reception ratio (PRR) by 19% and successful transmission by 30% over the reference protocols. In addition, NA-MAC reduced the packet collisions by a factor of 4. Using the real on-board units (OBUs), we conducted an experiment where our protocol outperformed in terms of PRR and average transmission interval by 82% and 49%, respectively.

ACS Style

Odilbek Urmonov; Hyungwon Kim. Highly Reliable MAC Protocol Based on Associative Acknowledgement for Vehicular Network. Electronics 2021, 10, 382 .

AMA Style

Odilbek Urmonov, Hyungwon Kim. Highly Reliable MAC Protocol Based on Associative Acknowledgement for Vehicular Network. Electronics. 2021; 10 (4):382.

Chicago/Turabian Style

Odilbek Urmonov; Hyungwon Kim. 2021. "Highly Reliable MAC Protocol Based on Associative Acknowledgement for Vehicular Network." Electronics 10, no. 4: 382.

Journal article
Published: 19 January 2021 in Sensors
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5G-Vehicle-to-Everything (5G-V2X) supports high-reliability and low latency autonomous services and applications. Proposing an efficient security solution that supports multi-zone broadcast authentication and satisfies the 5G requirement is a critical challenge. In The 3rd Generation Partnership Project (3GPP) Release 16 standard, for Cellular- Vehicle-to-Everything (C-V2X) single-cell communication is suggested to reuse the IEEE1609.2 security standard that utilizes the Public Key Infrastructure (PKI) cryptography. PKI-based solutions provide a high-security level, however, it suffers from high communication and computation overhead, due to the large size of the attached certificate and signature. In this study, we propose a light-weight Multi-Zone Authentication and Privacy-Preserving Protocol (MAPP) based on the bilinear pairing cryptography and short-size signature. MAPP protocol provides three different authentication methods that enable a secure broadcast authentication over multiple zones of large-scale base stations, using a single message and a single short signature. We also propose a centralized dynamic key generation method for multiple zones. We implemented and analyzed the proposed key generation and authentication methods using an authentication simulator and a bilinear pairing library. The proposed methods significantly reduce the signature generation time by 16 times–80 times, as compared to the previous methods. Additionally, the proposed methods significantly reduced the signature verification time by 10 times–16 times, as compared to the two previous methods. The three proposed authentication methods achieved substantial speed-up in the signature generation time and verification time, using a short bilinear pairing signature.

ACS Style

Shimaa Hakeem; Hyungwon Kim. Multi-Zone Authentication and Privacy-Preserving Protocol (MAPP) Based On the Bilinear Pairing Cryptography for 5G-V2X. Sensors 2021, 21, 665 .

AMA Style

Shimaa Hakeem, Hyungwon Kim. Multi-Zone Authentication and Privacy-Preserving Protocol (MAPP) Based On the Bilinear Pairing Cryptography for 5G-V2X. Sensors. 2021; 21 (2):665.

Chicago/Turabian Style

Shimaa Hakeem; Hyungwon Kim. 2021. "Multi-Zone Authentication and Privacy-Preserving Protocol (MAPP) Based On the Bilinear Pairing Cryptography for 5G-V2X." Sensors 21, no. 2: 665.

Letter
Published: 04 November 2020 in Sensors
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Modern sensor nodes have multiple operating states, which causes a conventional voltage converter to perform poorly over a wide load range of the operating states. This paper proposes a voltage converter whose switching frequency and output voltage are proactively adjusted to maintain high conversion efficiency. This allows the converter to exploit a wider frequency range to cover a wide load range. In addition, the proposed converter uses multiple smaller capacitor banks and employs multiphase operation to provide low output ripple voltage. A distributed topology for non-overlapping signal generation is proposed and used in the converter to minimize the number of wires running from connecting the controller to the converter. The proposed voltage converter has been implemented in a chip using a 0.13 um CMOS process. The measurement results demonstrate the ability to support a wide load range of 10 µA to 10 mA, for switching frequencies ranging from 100 kHz to 200 MHz, while providing an efficiency of above 80%.

ACS Style

Saad Arslan; Syed Asmat Ali Shah; Hyungwon Kim. An Ultra-Wide Load Range Voltage Converter Using Proactive Phase Frequency Modulation for IoT Sensors. Sensors 2020, 20, 6279 .

AMA Style

Saad Arslan, Syed Asmat Ali Shah, Hyungwon Kim. An Ultra-Wide Load Range Voltage Converter Using Proactive Phase Frequency Modulation for IoT Sensors. Sensors. 2020; 20 (21):6279.

Chicago/Turabian Style

Saad Arslan; Syed Asmat Ali Shah; Hyungwon Kim. 2020. "An Ultra-Wide Load Range Voltage Converter Using Proactive Phase Frequency Modulation for IoT Sensors." Sensors 20, no. 21: 6279.

Journal article
Published: 04 November 2020 in IEEE Access
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In vehicular networks, messages from vehicles are signed before being broadcasted to ensure the authenticity and integrity of the messages. Due to the high mobility of vehicular networks, frequent key updates are often required, which imposes an excessive burden on the key generation process. In this paper, we propose a dynamic authentication with conditional privacy-preservation using matrix-based signature generation (DACOP), which is well suited to Vehicle-to-Everything (V2X) networks. The proposed authentication method also provides conditional privacy by utilizing a dynamic pseudo-identity and anonymity of the vehicle. In addition, it can significantly reduce the computation overhead for signature generation. We implemented DACOP and analyzed its computation and communication overhead compared with previous methods. Furthermore, our experimental results using real V2X networks demonstrate that DACOP reduces the computation time by 90% while enhancing the security level by 2 times over previous methods.

ACS Style

Hayotjon Aliev; Hyung-Won Kim. Matrix-Based Dynamic Authentication With Conditional Privacy-Preservation for Vehicular Network Security. IEEE Access 2020, 8, 200883 -200896.

AMA Style

Hayotjon Aliev, Hyung-Won Kim. Matrix-Based Dynamic Authentication With Conditional Privacy-Preservation for Vehicular Network Security. IEEE Access. 2020; 8 (99):200883-200896.

Chicago/Turabian Style

Hayotjon Aliev; Hyung-Won Kim. 2020. "Matrix-Based Dynamic Authentication With Conditional Privacy-Preservation for Vehicular Network Security." IEEE Access 8, no. 99: 200883-200896.

Journal article
Published: 28 October 2020 in Sensors
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Safety applications based on vehicle-to-everything (V2X) communications can significantly enhance road safety and reduce traffic fatalities. Ensuring the security and privacy of the vehicular network is essential for the widespread adoption of V2X communications for commercial use. V2X safety and service applications require periodic broadcast communications among all the vehicles. However, compared to unicast communication, it is extremely challenging to provide broadcast communication with network security requirements such as confidentiality, in infotainment contents distribution, sensor data sharing, and security credentials management services. To address the providing confidentiality of vehicle-to-vehicle (V2V) broadcasting, we propose a group key management and message encryption method that is secure, lightweight, and scalable. The proposed group key management method can efficiently handle various scenarios like a node joining or leaving the group, with scalable rekeying algorithms. It employs a distributed and scalable architecture that offers several advantages such as the reduction of the key management overhead and the enhancement of the security level by keeping the key sizes with large networks. In addition, the proposed method employs a lightweight matrix-based encryption algorithm that can be easily applicable with the proposed group key management method. Further, we have implemented the proposed method and evaluated the performance using a V2V network simulator with several networks of highly dynamic group members. The simulation results show that the proposed method can reduce computation time for group key generation and message encryption by more than 80% compared to existing methods.

ACS Style

Hayotjon Aliev; Hyungwon Kim; Sunghyun Choi. A Scalable and Secure Group Key Management Method for Secure V2V Communication. Sensors 2020, 20, 6137 .

AMA Style

Hayotjon Aliev, Hyungwon Kim, Sunghyun Choi. A Scalable and Secure Group Key Management Method for Secure V2V Communication. Sensors. 2020; 20 (21):6137.

Chicago/Turabian Style

Hayotjon Aliev; Hyungwon Kim; Sunghyun Choi. 2020. "A Scalable and Secure Group Key Management Method for Secure V2V Communication." Sensors 20, no. 21: 6137.

Journal article
Published: 20 October 2020 in Electronics
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To ensure the driving safety in vehicular network, it is necessary to construct a local dynamic map (LDM) for an extended range. Using the standard vehicular communication protocols, however, vehicles can construct the LDM for only one-hop range. Constructing large-scale LDM is highly challenging because vehicles randomly change their position. This paper proposes a dynamic map propagation (DMP) method, which builds a large aggregated LDM data using a multi-hop communication. To reduce the data overhead, we introduce an efficient clustering method based on a half-circle of the forwarder’s wireless range. The DMP elects one forwarder per cluster, which constructs LDM and forwards it to a neighbor cluster. The inter-cluster interference is minimized by allocating a different transmit window to each cluster. DMP copes with a dynamic environment by frequently re-electing the forwarders and their associated transmission windows. Simulation results reveal that DMP enhances the forwarders’ reception ratio by 20%, while extending LDM dissemination range by 29% over a previous work.

ACS Style

Odilbek Urmonov; Hyungwon Kim. Multi-Hop Dynamic Map Data Propagation Algorithm for Clustered Vehicular Networks. Electronics 2020, 9, 1728 .

AMA Style

Odilbek Urmonov, Hyungwon Kim. Multi-Hop Dynamic Map Data Propagation Algorithm for Clustered Vehicular Networks. Electronics. 2020; 9 (10):1728.

Chicago/Turabian Style

Odilbek Urmonov; Hyungwon Kim. 2020. "Multi-Hop Dynamic Map Data Propagation Algorithm for Clustered Vehicular Networks." Electronics 9, no. 10: 1728.

Journal article
Published: 08 October 2020 in Sensors
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Vehicle-to-everything (V2X) is the communication technology designed to support road safety for drivers and autonomous driving. The light-weight security solution is crucial to meet the real-time needs of on-board V2X applications. However, most of the recently proposed V2X security protocols—based on the Elliptic Curve Digital Signature Algorithm (ECDSA)—are not efficient enough to support fast processing and reduce the communication overhead between vehicles. ECDSA provides a high-security level at the cost of excessive communication and computation overhead, which motivates us to propose a light-weight message authentication and privacy preservation protocol for V2X communications. The proposed protocol achieves highly secure message authentication at a substantially lower cost by introducing a hash chain of secret keys for a Message Authentication Code (MAC). We implemented the proposed protocol using commercial V2X devices to prove its performance advantages over the standard and non-standard protocols. We constructed real V2X networks using commercial V2X devices that run our implemented protocol. Our extensive experiments with real networks demonstrate that the proposed protocol reduces the communication overhead by 6 times and computation overhead by more than 100 times compared with the IEEE1609.2 standard. Moreover, the proposed protocol reduces the communication overhead by 4 times and the computation overhead by up to 100 times compared with a non-standard security protocol, TESLA. The proposed protocol substantially reduces the average end-to-end delay to 2.5 ms, which is a 24- and 28-fold reduction, respectively, compared with the IEEE1609 and TESLA protocols.

ACS Style

Shimaa A. Abdel Hakeem; Mohamed A. Abd El-Gawad; Hyungwon Kim. Comparative Experiments of V2X Security Protocol Based on Hash Chain Cryptography. Sensors 2020, 20, 5719 .

AMA Style

Shimaa A. Abdel Hakeem, Mohamed A. Abd El-Gawad, Hyungwon Kim. Comparative Experiments of V2X Security Protocol Based on Hash Chain Cryptography. Sensors. 2020; 20 (19):5719.

Chicago/Turabian Style

Shimaa A. Abdel Hakeem; Mohamed A. Abd El-Gawad; Hyungwon Kim. 2020. "Comparative Experiments of V2X Security Protocol Based on Hash Chain Cryptography." Sensors 20, no. 19: 5719.

Journal article
Published: 29 September 2020 in Electronics
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Spiking neural networks (SNN) increasingly attract attention for their similarity to the biological neural system. Hardware implementation of spiking neural networks, however, remains a great challenge due to their excessive complexity and circuit size. This work introduces a novel optimization method for hardware friendly SNN architecture based on a modified rate coding scheme called Binary Streamed Rate Coding (BSRC). BSRC combines the features of both rate and temporal coding. In addition, by employing a built-in randomizer, the BSRC SNN model provides a higher accuracy and faster training. We also present SNN optimization methods including structure optimization and weight quantization. Extensive evaluations with MNIST SNNs demonstrate that the structure optimization of SNN (81-30-20-10) provides 183.19 times reduction in hardware compared with SNN (784-800-10), while providing an accuracy of 95.25%, a small loss compared with 98.89% and 98.93% reported in the previous works. Our weight quantization reduces 32-bit weights to 4-bit integers leading to further hardware reduction of 4 times with only 0.56% accuracy loss. Overall, the SNN model (81-30-20-10) optimized by our method shrinks the SNN’s circuit area from 3089.49 mm2 for SNN (784-800-10) to 4.04 mm2—a reduction of 765 times.

ACS Style

Ali A. Al-Hamid; Hyungwon Kim. Optimization of Spiking Neural Networks Based on Binary Streamed Rate Coding. Electronics 2020, 9, 1599 .

AMA Style

Ali A. Al-Hamid, Hyungwon Kim. Optimization of Spiking Neural Networks Based on Binary Streamed Rate Coding. Electronics. 2020; 9 (10):1599.

Chicago/Turabian Style

Ali A. Al-Hamid; Hyungwon Kim. 2020. "Optimization of Spiking Neural Networks Based on Binary Streamed Rate Coding." Electronics 9, no. 10: 1599.

Article
Published: 06 August 2020 in Telecommunication Systems
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Vehicle to Everything (V2X) communication is a technology that provides connectivity between vehicles, pedestrians, and road infrastructure. Dedicated Short-Range Communication (DSRC) is proposed by different standards such as ETSI, IEEE, and others since ten years ago to provide wireless connectivity in V2X. Recently, the LTE-V2X based cellular communication is standardized by the 3rd Generation Partner Project (3GPP) Release 14 as an alternative V2X technology to support autonomous driving. 5G-NewRadio (5G-NR) is being proposed by the 3GPP Release 16 as a new radio access technology to offer enhanced radio coverage and wide ultra-high reliability services. 3GPP Release15 was published in 2018 to include Phase 1 5G-NR standard. 3GPP Release 16 is designed to provide the 5G phase 2 and scheduled for being delivered in June 2020. In this paper, we study V2X based DSRC and LTE-V2X standards and introduce the current 5G-V2X standards progress. We present the 5G-V2X architecture design, core elements, challenges, essential requirements, security enhancement, and radio techniques. Also, we consider the security aspects of architecture and issues of 5G-V2X.

ACS Style

Shimaa A. Abdel Hakeem; Anar A. Hady; Hyungwon Kim. Current and future developments to improve 5G-NewRadio performance in vehicle-to-everything communications. Telecommunication Systems 2020, 75, 1 -23.

AMA Style

Shimaa A. Abdel Hakeem, Anar A. Hady, Hyungwon Kim. Current and future developments to improve 5G-NewRadio performance in vehicle-to-everything communications. Telecommunication Systems. 2020; 75 (3):1-23.

Chicago/Turabian Style

Shimaa A. Abdel Hakeem; Anar A. Hady; Hyungwon Kim. 2020. "Current and future developments to improve 5G-NewRadio performance in vehicle-to-everything communications." Telecommunication Systems 75, no. 3: 1-23.

Article
Published: 11 July 2020 in Wireless Networks
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Vehicular communication is one of the critical technologies in intelligent transportation system to provide connectivity between vehicles, road side units, and pedestrians. Multiple wireless accessing technologies designed to provide connectivity in vehicular networks such as conventional Wi-Fi, IEEE 802.11p, and cellular communications. Recently, cellular V2X (C-V2X) is standardized and designed by the third generation partnership project (3GPP) for automotive services. C-V2X supports two communication modes through a single platform to provide both Wi-Fi and cellular communication. LTE-V2X is the current 3GPPRelease 14 standard that has many enhancements to provide the new 3GPPRelease 16 for the new 5G radio generation. 5G-new radio (NR) is expected to address the automotive capabilities, improvement, and services for 2020 and beyond. 5G-NR becomes a competitive technology compared with other wireless technologies because of extensive coverage, high capacity, high reliability, and low delay support. In this paper, we propose the Optimizing of 5G with V2X, and analyzing the current V2X standards, introducing the development of 5G, challenges, features, requirements, design, and technologies.

ACS Style

Shimaa A. Abdel Hakeem; Anar A. Hady; Hyungwon Kim. 5G-V2X: standardization, architecture, use cases, network-slicing, and edge-computing. Wireless Networks 2020, 26, 6015 -6041.

AMA Style

Shimaa A. Abdel Hakeem, Anar A. Hady, Hyungwon Kim. 5G-V2X: standardization, architecture, use cases, network-slicing, and edge-computing. Wireless Networks. 2020; 26 (8):6015-6041.

Chicago/Turabian Style

Shimaa A. Abdel Hakeem; Anar A. Hady; Hyungwon Kim. 2020. "5G-V2X: standardization, architecture, use cases, network-slicing, and edge-computing." Wireless Networks 26, no. 8: 6015-6041.

Journal article
Published: 31 March 2020 in Computers
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In vehicular networks, efficient multi-hop message dissemination can be used for various purposes, such a informing the driver about the recent emergency event or propagating the local dynamic map of a predefined region. Dissemination of warning information up to a longer distance can reduce the accidents on the road. It provides a driver additional time to react to the situations adequately and assists in finding a safe route towards the destination. The adopted V2X standards, ETSI TS’s C-ITS and IEEE 1609/IEEE 802.11p, specify only primitive multi-hop message dissemination schemes. IEEE 1609.4 standard disseminates the broadcast messages using the method of flooding, which causes high redundancy, severe congestion, and long delay during multi-hop propagation. To address these problems, we propose an effective broadcast message dissemination method. It introduces a notion of source Lateral Crossing Line (LCL) algorithm, which elects a set of relay vehicles for each hop based on the vehicle locations in a way that reduces the redundant retransmission and congestion, consequently minimizing the delays. Our simulation results demonstrated that the proposed method can achieve about 15% reduction in delays and 2 times the enhancement in propagation distance compared with the previous methods.

ACS Style

Odilbek Urmonov; Hyungwon Kim. A Multi-Hop Data Dissemination Algorithm for Vehicular Communication. Computers 2020, 9, 25 .

AMA Style

Odilbek Urmonov, Hyungwon Kim. A Multi-Hop Data Dissemination Algorithm for Vehicular Communication. Computers. 2020; 9 (2):25.

Chicago/Turabian Style

Odilbek Urmonov; Hyungwon Kim. 2020. "A Multi-Hop Data Dissemination Algorithm for Vehicular Communication." Computers 9, no. 2: 25.

Journal article
Published: 22 November 2019 in Electronics
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The analysis of frame sequences in talk show videos, which is necessary for media mining and television production, requires significant manual efforts and is a very time-consuming process. Given the vast amount of unlabeled face frames from talk show videos, we address and propose a solution to the problem of recognizing and clustering faces. In this paper, we propose a TV media mining system that is based on a deep convolutional neural network approach, which has been trained with a triplet loss minimization method. The main function of the proposed system is the indexing and clustering of video data for achieving an effective media production analysis of individuals in talk show videos and rapidly identifying a specific individual in video data in real-time processing. Our system uses several face datasets from Labeled Faces in the Wild (LFW), which is a collection of unlabeled web face images, as well as YouTube Faces and talk show faces datasets. In the recognition (person spotting) task, our system achieves an F-measure of 0.996 for the collection of unlabeled web face images dataset and an F-measure of 0.972 for the talk show faces dataset. In the clustering task, our system achieves an F-measure of 0.764 and 0.935 for the YouTube Faces database and the LFW dataset, respectively, while achieving an F-measure of 0.832 for the talk show faces dataset, an improvement of 5.4%, 6.5%, and 8.2% over the previous methods.

ACS Style

Mohamed S. Abdallah; Hyungwon Kim; Mohammad E. Ragab; Elsayed E. Hemayed. Zero-Shot Deep Learning for Media Mining: Person Spotting and Face Clustering in Video Big Data. Electronics 2019, 8, 1394 .

AMA Style

Mohamed S. Abdallah, Hyungwon Kim, Mohammad E. Ragab, Elsayed E. Hemayed. Zero-Shot Deep Learning for Media Mining: Person Spotting and Face Clustering in Video Big Data. Electronics. 2019; 8 (12):1394.

Chicago/Turabian Style

Mohamed S. Abdallah; Hyungwon Kim; Mohammad E. Ragab; Elsayed E. Hemayed. 2019. "Zero-Shot Deep Learning for Media Mining: Person Spotting and Face Clustering in Video Big Data." Electronics 8, no. 12: 1394.

Letter
Published: 08 November 2019 in Electronics
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Vertical-cavity surface-emitting lasers (VCSELs) are commonly used in high-speed optical communication and 3D sensing applications. Both of these applications require high switching frequency and a short rise time of the VCSEL current. The parasitic inductance of the wire (connecting the driver with VCSEL) makes it challenging to achieve a short rise time, which often incur increased supply voltage and excessive power consumption. This paper utilizes a momentary boosting in supply voltage to overcome the parasitic inductance of the wire with minimal power overhead. The proposed technique uses a precalculated boosting capacitance to produce negative voltage for common-anode VCSELs. The boosting capacitance provides the required amount of charge during the rising transition and automatically disconnects itself in steady-state. Circuit simulations reveal up to three times shorter rise time at the negligible cost of less than 10% power overhead.

ACS Style

Saad Arslan; Syed Asmat Ali Shah; Hyungwon Kim. Power Efficient Current Driver Based on Negative Boosting for High-Speed Lasers. Electronics 2019, 8, 1309 .

AMA Style

Saad Arslan, Syed Asmat Ali Shah, Hyungwon Kim. Power Efficient Current Driver Based on Negative Boosting for High-Speed Lasers. Electronics. 2019; 8 (11):1309.

Chicago/Turabian Style

Saad Arslan; Syed Asmat Ali Shah; Hyungwon Kim. 2019. "Power Efficient Current Driver Based on Negative Boosting for High-Speed Lasers." Electronics 8, no. 11: 1309.

Journal article
Published: 14 October 2019 in IEEE Transactions on Circuits and Systems II: Express Briefs
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Modern internet-of-things (IoT) applications need voltage converters to efficiently supply power with a small active period at various load conditions. The energy losses in such voltage converters during transitions between sleep-active can be significant, especially when the converters deviate from their optimum load conditions. The proposed Switched Capacitor (SC) converter, fully integrated on chip, incorporates Split-Capacitor Charging (SCC) and Energy Recycling (ER) techniques to minimize the energy losses during the transitions. The converter consists of multiple capacitor banks and their size increases in a binary exponential fashion. It employs an LDO to support a wide range of output voltage levels and reduce output voltage ripple during energy recycling and Continuous phase. In addition, we introduce an efficient test circuit structure using an on-chip digital controller and reconfigurable load circuit. This test structure can eliminate the unwanted parasitic values and varying delays, which are commonly incurred in the conventional test structures of on-chip voltage converters with off-chip loads and external control signal generation. We implemented the proposed voltage converter with a complete on-chip test structure using a 0.13um CMOS process. Measurement results demonstrate a maximum efficiency of 86.83% for a load current of μA It also achieved an improvement of 64.44% in energy efficiency over conventional voltage converters for a short active period.

ACS Style

Syed Asmat Ali Shah; Saad Arslan; Jae-Jin Lee; Bo-Seok Seo; Hyung Won Kim. A Switched Capacitor Voltage Converter With Exponentially Sized Capacitor Banks for Wide Load Range. IEEE Transactions on Circuits and Systems II: Express Briefs 2019, 67, 2049 -2053.

AMA Style

Syed Asmat Ali Shah, Saad Arslan, Jae-Jin Lee, Bo-Seok Seo, Hyung Won Kim. A Switched Capacitor Voltage Converter With Exponentially Sized Capacitor Banks for Wide Load Range. IEEE Transactions on Circuits and Systems II: Express Briefs. 2019; 67 (10):2049-2053.

Chicago/Turabian Style

Syed Asmat Ali Shah; Saad Arslan; Jae-Jin Lee; Bo-Seok Seo; Hyung Won Kim. 2019. "A Switched Capacitor Voltage Converter With Exponentially Sized Capacitor Banks for Wide Load Range." IEEE Transactions on Circuits and Systems II: Express Briefs 67, no. 10: 2049-2053.

Letter
Published: 26 July 2019 in Electronics
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This letter analyzes the meta-distribution of the transmission success probability (TSP) for vehicular networks based on a one-dimensional Poisson point process (PPP). We also propose a method to maximize the throughput across the vehicular network. Compared to the conventional spatial average performance assessment, the meta-distribution reveals the fraction of vehicles that operate at a target success rate of transmission across the highway. To this end, we propose a per-vehicle rate selection scheme to keep a target quality of service (QoS) level for all vehicles. The results reveal that operating at the spatially-averaged maximum throughput may lead to excessive variation in the performance of individual vehicles. However, with the proposed meta-distribution-aware rate selection scheme, the throughput variation among the vehicles can be significantly reduced (e.g., up to a 60% reduction).

ACS Style

Mohamed A. Abd El-Gawad; Hesham ElSawy; Ahmed Hamdi Sakr; Hyungwon Kim; Mohamed Abd El-Gawad. Network-Wide Throughput Optimization for Highway Vehicle-To-Vehicle Communications. Electronics 2019, 8, 830 .

AMA Style

Mohamed A. Abd El-Gawad, Hesham ElSawy, Ahmed Hamdi Sakr, Hyungwon Kim, Mohamed Abd El-Gawad. Network-Wide Throughput Optimization for Highway Vehicle-To-Vehicle Communications. Electronics. 2019; 8 (8):830.

Chicago/Turabian Style

Mohamed A. Abd El-Gawad; Hesham ElSawy; Ahmed Hamdi Sakr; Hyungwon Kim; Mohamed Abd El-Gawad. 2019. "Network-Wide Throughput Optimization for Highway Vehicle-To-Vehicle Communications." Electronics 8, no. 8: 830.

Journal article
Published: 16 May 2019 in IEEE Transactions on Circuits and Systems I: Regular Papers
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Low-power circuits often employ dynamic voltage scaling and energy harvesting. Such circuits need a power management unit that can convert the voltage source to a wide range of target voltages with high efficiency. Targeting such a power management unit, this paper presents a reconfigurable architecture of switched capacitor (SC) voltage converter. It introduces a design optimization methodology that can determine trade-off among design parameters to meet the goal. The proposed converter employs a reconfigurable topology with four capacitors. It provides 11 conversion ratios: 6 step-down and 5 step-up ratios supporting wide input/output voltage range. An analytical model for the output impedance of the proposed reconfigurable SC topology is presented. Using the model, the proposed optimization methodology can minimize the total power dissipation. To validate the proposed architecture and optimization methodology, the converter has been implemented in a 130-nm CMOS process using integrated capacitors of total size 2.2 nF. Simulation results show that the optimized converter circuit achieves an efficiency range from 83.41% to 74.69% for a load current of 100 μA.

ACS Style

Ahmed M. Mohey; Sameh A. Ibrahim; Ismail M. Hafez; Hyungwon Kim. Design Optimization for Low-Power Reconfigurable Switched-Capacitor DC-DC Voltage Converter. IEEE Transactions on Circuits and Systems I: Regular Papers 2019, 66, 4079 -4092.

AMA Style

Ahmed M. Mohey, Sameh A. Ibrahim, Ismail M. Hafez, Hyungwon Kim. Design Optimization for Low-Power Reconfigurable Switched-Capacitor DC-DC Voltage Converter. IEEE Transactions on Circuits and Systems I: Regular Papers. 2019; 66 (10):4079-4092.

Chicago/Turabian Style

Ahmed M. Mohey; Sameh A. Ibrahim; Ismail M. Hafez; Hyungwon Kim. 2019. "Design Optimization for Low-Power Reconfigurable Switched-Capacitor DC-DC Voltage Converter." IEEE Transactions on Circuits and Systems I: Regular Papers 66, no. 10: 4079-4092.

Journal article
Published: 01 March 2019 in IEEE Sensors Letters
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ACS Style

Mahmoud Abdelsamad ElSharief; Mohamed A. Abd El-Gawad; Hyungwon Kim; Mohamed Abd El-Gawad. Low-Power Scheduling for Time Synchronization Protocols in A Wireless Sensor Networks. IEEE Sensors Letters 2019, 3, 1 -4.

AMA Style

Mahmoud Abdelsamad ElSharief, Mohamed A. Abd El-Gawad, Hyungwon Kim, Mohamed Abd El-Gawad. Low-Power Scheduling for Time Synchronization Protocols in A Wireless Sensor Networks. IEEE Sensors Letters. 2019; 3 (4):1-4.

Chicago/Turabian Style

Mahmoud Abdelsamad ElSharief; Mohamed A. Abd El-Gawad; Hyungwon Kim; Mohamed Abd El-Gawad. 2019. "Low-Power Scheduling for Time Synchronization Protocols in A Wireless Sensor Networks." IEEE Sensors Letters 3, no. 4: 1-4.

Journal article
Published: 15 February 2019 in Energies
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This paper introduces a reference-free, scalable, and energy-efficient dynamic voltage scaler (DVS) that can be reconfigured for multiple outputs. The proposed DVS employs a novel swapping switched-capacitor (SSC) technique, which can generate target output voltages with higher resolution and smaller ripple voltages than the conventional voltage scalers based on switched-capacitors. The proposed DVS consists of a cascaded 2:1 converter based on swapping capacitors, which is essential to achieve both very small voltage ripple and fine-grain conversion ratios. One of the serious drawbacks of the conventional voltage scalers is the need for external reference voltages to maintain the target output voltage. The proposed SSC; however, eliminates the needs for any reference voltages. This significant benefit is achieved by the self-charging ability of the SSC, which can recharge all its capacitors to the configured voltage by simply swapping the two capacitors in each stage. The proposed SSC-DVS was designed with a resolution of 16 output levels and implemented using a 130 nm CMOS (Complementary Metal Oxide semiconductor) process. We conducted measured results and post-layout simulations with an input voltage of 1.5 V to produce an output voltage range of 0.085–1.4 V, which demonstrated a power efficiency of 85% for a load current of 550 µA with a voltage ripple of as low as 2.656 mV for a 2 KΩ resistor load.

ACS Style

A. N. Ragheb; Hyung Won Kim. Reference-Free Dynamic Voltage Scaler Based on Swapping Switched-Capacitors. Energies 2019, 12, 625 .

AMA Style

A. N. Ragheb, Hyung Won Kim. Reference-Free Dynamic Voltage Scaler Based on Swapping Switched-Capacitors. Energies. 2019; 12 (4):625.

Chicago/Turabian Style

A. N. Ragheb; Hyung Won Kim. 2019. "Reference-Free Dynamic Voltage Scaler Based on Swapping Switched-Capacitors." Energies 12, no. 4: 625.

Journal article
Published: 05 February 2019 in Electronics
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The Advanced Metering Infrastructure (AMI) is one of the Smart Grid (SG) applications that used to upgrade the current power system by proposing a two-way communication system to connect the smart meter devices at homes with the electric control company. The design and deployment of an efficient routing protocol solution for AMI systems are considered to be a critical challenge due to the constrained resources of the smart meter nodes. IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) was recently standardized by the IETF and originally designed to satisfy the routing requirements of lossy and low power networks like wireless sensors (WSN). We have two kinds of AMI applications, on one hand AMI based WSN and on the other hand AMI based PLC communication. In this paper, we proposed a real and simulated implementation of RPL behavior with proper modifications to support the AMI based WSN routing requirements. We evaluate RPL performance using 140 nodes from the wireless sensor testbed (IoT-LAB) and 1000 nodes using Cooja simulator measure RPL performance within medium and high-density networks. We adopted two routing metrics for path selection: First one is HOP Count (HC) and the second is Expected Transmission Unit (ETX) to evaluate RPL performance in terms of packet delivery ratio; network latency; control traffic overhead; and power consumption. Our results illustrate that routes with ETX calculations in low and medium network densities outperform routes using HC and the performance decreases as the network becomes dense. However, Cooja implementation results provides an average reasonable performance for AMI with high-density networks; still many RPL nodes suffering from high packet loss rates, network congestion and many retransmissions due to the selection of optimal paths with highly unreliable links.

ACS Style

Shimaa A. Abdel Hakeem; Anar Abdel Hady; Hyungwon Kim. RPL Routing Protocol Performance in Smart Grid Applications Based Wireless Sensors: Experimental and Simulated Analysis. Electronics 2019, 8, 186 .

AMA Style

Shimaa A. Abdel Hakeem, Anar Abdel Hady, Hyungwon Kim. RPL Routing Protocol Performance in Smart Grid Applications Based Wireless Sensors: Experimental and Simulated Analysis. Electronics. 2019; 8 (2):186.

Chicago/Turabian Style

Shimaa A. Abdel Hakeem; Anar Abdel Hady; Hyungwon Kim. 2019. "RPL Routing Protocol Performance in Smart Grid Applications Based Wireless Sensors: Experimental and Simulated Analysis." Electronics 8, no. 2: 186.

Journal article
Published: 17 December 2018 in Electronics
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Conventional IoT applications rely on seamless data collection from the distributed sensor nodes of Wireless Sensor Networks (WSNs). The energy supplied to the sensor node is limited and it depletes after each cycle of data collection. Therefore, data flow from the network to the base station may cease at any time due to the nodes with a dead battery. A replacement of the battery in WSNs is often challenging and requires additional efforts. To ensure the robust operation of WSNs, many fault recovery routing mechanisms have been proposed. Most of the previous fault recovery routing methods incur considerable delays in recovery and high overhead in either energy consumption or device cost. We propose an energy-efficient fail recovery routing method that is aimed to operate over a data aggregation network topology using a TDMA media access control (MAC). This paper introduces a novel fault recovery routing algorithm for TDMA-based WSNs. It finds an optimal neighbor backup parent (NBP) for each node in a way that reduces the energy consumption. The proposed method allows the NBPs to utilize the time slot of the faulty parent nodes, so it eliminates the overhead of TDMA rescheduling for NBPs. To evaluate the fault recovery performance and energy efficiency of the proposed method, we implemented it in C++ simulation program. Simulation experiments with an extensive set of network examples demonstrate that the proposed method can extend the network lifetime by 21% and reduce the energy consumption by 23% compared with the reference methods.

ACS Style

Odilbek Urmonov; Hyungwon Kim. An Energy-Efficient Fail Recovery Routing in TDMA MAC Protocol-Based Wireless Sensor Network. Electronics 2018, 7, 444 .

AMA Style

Odilbek Urmonov, Hyungwon Kim. An Energy-Efficient Fail Recovery Routing in TDMA MAC Protocol-Based Wireless Sensor Network. Electronics. 2018; 7 (12):444.

Chicago/Turabian Style

Odilbek Urmonov; Hyungwon Kim. 2018. "An Energy-Efficient Fail Recovery Routing in TDMA MAC Protocol-Based Wireless Sensor Network." Electronics 7, no. 12: 444.