Node movement feature of Vehicular ad hoc network (VANET) closely resembles with that of mobile a... more Node movement feature of Vehicular ad hoc network (VANET) closely resembles with that of mobile ad hoc network (MANET) but its high speed mobility and unpredictable movement characteristics are the key contrasting feature from that of MANET. The similarity nature suggests that the prevailing routing protocol of MANET is very much applicable to VANET. However, on the same line, the dissimilarity characteristics result in frequent loss of connectivity. This necessitates upgradation of the existing routing protocols to adapt itself into VANET scenario. The key parameter that needs to be fed into these protocols is a realistic mobility model which contains criterion linked to speed, road intersections, traffic light effect etc. In this paper, we compare performances of reactive routing protocols named Dynamic Source Routing (DSR), Ad hoc On Demand Distance Vector (AODV) and Ad hoc On Demand Multipath Distance Vector (AOMDV) in VANET using different Mobility Models provided in VanetMobiSim framework. The performances are evaluated by varying mobility, number of sources and node speed while packet delivery fraction, end to end delay and normalized routing load are used as performance metrics. The simulations have shown that AOMDV performs comparatively better than DSR and AODV in different mobility models in terms of end to end delay as performance metric.
IEEE 802.11ah, known as Wi-Fi HaLow, is envisioned for long-range and low-power communication. It... more IEEE 802.11ah, known as Wi-Fi HaLow, is envisioned for long-range and low-power communication. It is sub-1 GHz technology designed for massive Internet of Things (IoT) and machine-to-machine devices. It aims to overcome the IoT challenges, such as providing connectivity to massive power-constrained devices distributed over a large geographical area. To accomplish this objective, IEEE 802.11ah introduces several unique physical and medium access control layer (MAC) features. In recent years, the MAC features of IEEE 802.11ah, including restricted access window, authentication (e.g., centralized and distributed) and association, relay and sectorization, target wake-up time, and traffic indication map, have been intensively investigated from various aspects to improve resource allocation and enhance the network performance in terms of device association time, throughput, delay, and energy consumption. This survey paper presents an in-depth assessment and analysis of these MAC features ...
Terahertz (THz) is a promising technology for future wireless communication networks, particularl... more Terahertz (THz) is a promising technology for future wireless communication networks, particularly for 6G and beyond. The ultra-wide THz band, ranging from 0.1 to 10 THz, can potentially address the limited capacity and scarcity of spectrum in current wireless systems such as 4G-LTE and 5G. Furthermore, it is expected to support advanced wireless applications requiring high data transmission and quality services, i.e., terabit-per-second backhaul systems, ultra-high-definition streaming, virtual/augmented reality, and high-bandwidth wireless communications. In recent years, artificial intelligence (AI) has been used mainly for resource management, spectrum allocation, modulation and bandwidth classification, interference mitigation, beamforming, and medium access control layer protocols to improve THz performance. This survey paper examines the use of AI in state-of-the-art THz communications, discussing the challenges, potentials, and shortcomings. Additionally, this survey discuss...
Journal of the Institute of Electronics Engineers of Korea, 2008
Streaming video has become a popular form of transferring media over the wired/wireless network. ... more Streaming video has become a popular form of transferring media over the wired/wireless network. TCP-friendly rate control (TFRC) is used as a streaming media transport protocol. Using the TCP congestion response function and current network conditions, TFRC adjusts its sending rate to yield the maximum TCP-friendly throughput. Since TFRC was designed for applications that would prefer to maintain a slowly-changing sending rate, it is less responsive to changes in handover between wireless heterogeneous networks such as 3G network, WLAN, and so on. This paper shows a new TFRC method for vertical handover over wireless heterogeneous network. The proposed TFRC method has features of low quality interruption and fast rate adaptation to a new target network. The simulation results show that the proposed one provides better QoS and throughput support than the traditional TFRC scheme during vertical handover.
2014 48th Asilomar Conference on Signals, Systems and Computers, 2014
The TOA trilateration method decides the location of MS using an intersection point of three circ... more The TOA trilateration method decides the location of MS using an intersection point of three circles with centers corresponding three base station (BS) coordinates and radius based on the distance between MS and three BSs. Since the distance between BS and MS is generally estimated counting the number of time delay samples, the estimated distances are slightly increased and three circles may not intersect at a point. In this paper, we introduce the shortest distance and line intersection algorithms for improving conventional TOA trilateration method to resolve above problem. Also, the mathematic analysis is provided to indicate the relation between both algorithms.
2020 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia)
Currently, LoRaWAN employs the use of an adaptive data rate (ADR), which aims to provide reliable... more Currently, LoRaWAN employs the use of an adaptive data rate (ADR), which aims to provide reliable and battery-efficient communication by managing the spreading factor (SF) and transmit power. However, the variable channel conditions severely affect the performance of ADR, resulting in massive packet loss. In this paper, we propose an improved ADR (I-ADR), which allocates SFs to end devices based on the received signal strength at the gateway during the initial deployment. The I-ADR algorithm is evaluated in both confirmed and unconfirmed modes under the urban environment. Simulation results show that I-ADR performs better in terms of success ratio by lowering the impact of interference than the typical ADR.
Tracking the source of air pollution plumes and monitoring the air quality during emergency event... more Tracking the source of air pollution plumes and monitoring the air quality during emergency events in real-time is crucial to support decision-makers in making an appropriate evacuation plan. Internet of Things (IoT) based air quality tracking and monitoring platforms have used stationary sensors around the environment. However, fixed IoT sensors may not be enough to monitor the air quality in a vast area during emergency situations. Therefore, many applications consider utilizing Unmanned Aerial Vehicles (UAVs) to monitor the air pollution plumes environment. However, finding an unhealthy location in a vast area requires a long navigation time. For time efficiency, we employ deep reinforcement learning (Deep RL) to assist UAVs to find air pollution plumes in an equal-sized grid space. The proposed Deep Q-network (DQN) based UAV Pollution Tracking (DUPT) is utilized to guide the multi-navigation direction of the UAV to find the pollution plumes’ location in a vast area within a shor...
Recently, technologies such as big data, artificial intelligence, and machine learning have been ... more Recently, technologies such as big data, artificial intelligence, and machine learning have been applied to intelligently and effectively operate fourth-generation (4G) and fifth-generation (5G) network systems. In particular, we are interested in using them in 4G mobility management entities and 5G access and mobility management functions (AMFs), where functional enhancement or performance improvement is required. This paper presents an enhanced paging approach based on supervised machine learning and a Markov process for the performance improvement of paging in 5G AMFs. User equipment (UE) profile information in 5G AMFs classifies subscribers into two types using a UE classifier model with k-nearest neighbors (KNN)-supervised learning. In this paper, UE movement data between next-generation NodeBs (gNodeBs) are analyzed, and the Markov process is applied to construct a transition probabilistic model. When a UE moves to an adjacent gNodeB in the 5G connection management-idle state,...
2016 Eighth International Conference on Ubiquitous and Future Networks (ICUFN), 2016
Many studies are based on automatic or semi-automatic measurement of various a priori brain Regio... more Many studies are based on automatic or semi-automatic measurement of various a priori brain Region of Interest (ROI) to compare and discriminate between healthy controls (HC) and Alzheimer Disease (AD) patients. The proposed diagnosis method results yield up to about 84% stratification accuracy with Multi-kernel SVM along with high sensitivity and specificity above 85%.
Journal of the Institute of Electronics Engineers of Korea, 2007
Streaming video is expected to become a key service in the developing heterogeneous wireless netw... more Streaming video is expected to become a key service in the developing heterogeneous wireless network. However, sufficient quality of service is not offered to video applications because of bursty packet losses. An effective solution for packet loss in wireless network is to perform a proper concealment at the receiver. However, most concealment methods can not conceal effectively the consecutively damaged macro blocks, since the neighboring blocks are lost. In the previous work, bidirectional motion vector tracking (BMVT) method has been proposed which uses the moving trajectory feature of the damaged macro blocks. In this paper, a channel-adaptive redundancy coding method for the better BMVT error concealment is presented. The proposed method provides enhanced video quality at the cost of a little bit overhead in the wireless error-prone network.
2018 52nd Asilomar Conference on Signals, Systems, and Computers, 2018
The Global Positioning System (GPS) is designed to accurately estimate the location information o... more The Global Positioning System (GPS) is designed to accurately estimate the location information of objects, using signals from at least four GPS satellites. When the high-power interference signals exist, the GPS receiver does not have the proper estimation performance. In this case, we need to enhance the desired GPS signals and to efficiently suppress interference signals. For this purpose, the adaptive beamformer based on the angle-of-arrival (AOA) is widely employed, but the AOA information of the GPS signal is not easily estimated. After conventional despreading, GPS AOA can be estimated using various AOA estimation algorithms such as Multiple Signal Classification (MUSIC), but the estimated result includes not only GPS AOA but also interference AOA at the high-power interference environment. In this paper, we propose a GPS AOA estimation algorithm, based on the composite despreader and the null despreader for multiple GPS signals. The AOA estimation result based on the composi...
Background : The time of arrival (TOA) trilateration is one of the representative location detect... more Background : The time of arrival (TOA) trilateration is one of the representative location detection technologies (LDT), which determines the true location of mobile station (MS) using a unique intersection point of three circles based on three radiuses corresponding to distances between MS and base stations (BSs) and center coordinates of BSs. Since the distance between MS and BS is estimated by using the number of time delays, three circles based on the estimated radiuses are generally increased and they may not meet at a single point, resulting in the location estimation error. Aim : In order to compensate this estimation error and to improve estimation performance, we present two advanced TOA trilateration localization algorithms with detail mathematical expressions. Materials and Methods : The considered algorithms are the shortest distance algorithm, which calculates an average of three interior intersection points among entire six intersection points from three intersecting c...
The Journal of The Korea Institute of Intelligent Transport Systems, 2008
Wireless sensor network-related application system can perform functions such as environmental po... more Wireless sensor network-related application system can perform functions such as environmental pollution monitoring, building control, home automation in future. In this paper, we present wireless sensor network based system for subway station in order to reduce the damage of the people and the subway station due to fire. Sensor nodes in this system can sense temperature, illumination, smoke, and human body in real time and detect the accident in the subway station. These real-time sensing and wireless networking minimize casualties and damage to property.
2018 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia), 2018
Recently indoor positioning system (IPS) has been getting a lot of attention. Similarly, because ... more Recently indoor positioning system (IPS) has been getting a lot of attention. Similarly, because of low cost and ease of use, Bluetooth low energy (BLE) is extensively used for IPS. Techniques such as trilateration, triangulation, and fingerprinting are widely studied in IPS. Fingerprinting is popular approach in RSSI based-IPS, but is also time-consuming method. Here, we proposed to use the state-of-the-art machine learning approach for fingerprinting. This paper proposes a BLE based machine learning location and tracking system for indoor positioning. The experimental results showed that the proposed method has an average estimation error of 50 cm.
Node movement feature of Vehicular ad hoc network (VANET) closely resembles with that of mobile a... more Node movement feature of Vehicular ad hoc network (VANET) closely resembles with that of mobile ad hoc network (MANET) but its high speed mobility and unpredictable movement characteristics are the key contrasting feature from that of MANET. The similarity nature suggests that the prevailing routing protocol of MANET is very much applicable to VANET. However, on the same line, the dissimilarity characteristics result in frequent loss of connectivity. This necessitates upgradation of the existing routing protocols to adapt itself into VANET scenario. The key parameter that needs to be fed into these protocols is a realistic mobility model which contains criterion linked to speed, road intersections, traffic light effect etc. In this paper, we compare performances of reactive routing protocols named Dynamic Source Routing (DSR), Ad hoc On Demand Distance Vector (AODV) and Ad hoc On Demand Multipath Distance Vector (AOMDV) in VANET using different Mobility Models provided in VanetMobiSim framework. The performances are evaluated by varying mobility, number of sources and node speed while packet delivery fraction, end to end delay and normalized routing load are used as performance metrics. The simulations have shown that AOMDV performs comparatively better than DSR and AODV in different mobility models in terms of end to end delay as performance metric.
IEEE 802.11ah, known as Wi-Fi HaLow, is envisioned for long-range and low-power communication. It... more IEEE 802.11ah, known as Wi-Fi HaLow, is envisioned for long-range and low-power communication. It is sub-1 GHz technology designed for massive Internet of Things (IoT) and machine-to-machine devices. It aims to overcome the IoT challenges, such as providing connectivity to massive power-constrained devices distributed over a large geographical area. To accomplish this objective, IEEE 802.11ah introduces several unique physical and medium access control layer (MAC) features. In recent years, the MAC features of IEEE 802.11ah, including restricted access window, authentication (e.g., centralized and distributed) and association, relay and sectorization, target wake-up time, and traffic indication map, have been intensively investigated from various aspects to improve resource allocation and enhance the network performance in terms of device association time, throughput, delay, and energy consumption. This survey paper presents an in-depth assessment and analysis of these MAC features ...
Terahertz (THz) is a promising technology for future wireless communication networks, particularl... more Terahertz (THz) is a promising technology for future wireless communication networks, particularly for 6G and beyond. The ultra-wide THz band, ranging from 0.1 to 10 THz, can potentially address the limited capacity and scarcity of spectrum in current wireless systems such as 4G-LTE and 5G. Furthermore, it is expected to support advanced wireless applications requiring high data transmission and quality services, i.e., terabit-per-second backhaul systems, ultra-high-definition streaming, virtual/augmented reality, and high-bandwidth wireless communications. In recent years, artificial intelligence (AI) has been used mainly for resource management, spectrum allocation, modulation and bandwidth classification, interference mitigation, beamforming, and medium access control layer protocols to improve THz performance. This survey paper examines the use of AI in state-of-the-art THz communications, discussing the challenges, potentials, and shortcomings. Additionally, this survey discuss...
Journal of the Institute of Electronics Engineers of Korea, 2008
Streaming video has become a popular form of transferring media over the wired/wireless network. ... more Streaming video has become a popular form of transferring media over the wired/wireless network. TCP-friendly rate control (TFRC) is used as a streaming media transport protocol. Using the TCP congestion response function and current network conditions, TFRC adjusts its sending rate to yield the maximum TCP-friendly throughput. Since TFRC was designed for applications that would prefer to maintain a slowly-changing sending rate, it is less responsive to changes in handover between wireless heterogeneous networks such as 3G network, WLAN, and so on. This paper shows a new TFRC method for vertical handover over wireless heterogeneous network. The proposed TFRC method has features of low quality interruption and fast rate adaptation to a new target network. The simulation results show that the proposed one provides better QoS and throughput support than the traditional TFRC scheme during vertical handover.
2014 48th Asilomar Conference on Signals, Systems and Computers, 2014
The TOA trilateration method decides the location of MS using an intersection point of three circ... more The TOA trilateration method decides the location of MS using an intersection point of three circles with centers corresponding three base station (BS) coordinates and radius based on the distance between MS and three BSs. Since the distance between BS and MS is generally estimated counting the number of time delay samples, the estimated distances are slightly increased and three circles may not intersect at a point. In this paper, we introduce the shortest distance and line intersection algorithms for improving conventional TOA trilateration method to resolve above problem. Also, the mathematic analysis is provided to indicate the relation between both algorithms.
2020 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia)
Currently, LoRaWAN employs the use of an adaptive data rate (ADR), which aims to provide reliable... more Currently, LoRaWAN employs the use of an adaptive data rate (ADR), which aims to provide reliable and battery-efficient communication by managing the spreading factor (SF) and transmit power. However, the variable channel conditions severely affect the performance of ADR, resulting in massive packet loss. In this paper, we propose an improved ADR (I-ADR), which allocates SFs to end devices based on the received signal strength at the gateway during the initial deployment. The I-ADR algorithm is evaluated in both confirmed and unconfirmed modes under the urban environment. Simulation results show that I-ADR performs better in terms of success ratio by lowering the impact of interference than the typical ADR.
Tracking the source of air pollution plumes and monitoring the air quality during emergency event... more Tracking the source of air pollution plumes and monitoring the air quality during emergency events in real-time is crucial to support decision-makers in making an appropriate evacuation plan. Internet of Things (IoT) based air quality tracking and monitoring platforms have used stationary sensors around the environment. However, fixed IoT sensors may not be enough to monitor the air quality in a vast area during emergency situations. Therefore, many applications consider utilizing Unmanned Aerial Vehicles (UAVs) to monitor the air pollution plumes environment. However, finding an unhealthy location in a vast area requires a long navigation time. For time efficiency, we employ deep reinforcement learning (Deep RL) to assist UAVs to find air pollution plumes in an equal-sized grid space. The proposed Deep Q-network (DQN) based UAV Pollution Tracking (DUPT) is utilized to guide the multi-navigation direction of the UAV to find the pollution plumes’ location in a vast area within a shor...
Recently, technologies such as big data, artificial intelligence, and machine learning have been ... more Recently, technologies such as big data, artificial intelligence, and machine learning have been applied to intelligently and effectively operate fourth-generation (4G) and fifth-generation (5G) network systems. In particular, we are interested in using them in 4G mobility management entities and 5G access and mobility management functions (AMFs), where functional enhancement or performance improvement is required. This paper presents an enhanced paging approach based on supervised machine learning and a Markov process for the performance improvement of paging in 5G AMFs. User equipment (UE) profile information in 5G AMFs classifies subscribers into two types using a UE classifier model with k-nearest neighbors (KNN)-supervised learning. In this paper, UE movement data between next-generation NodeBs (gNodeBs) are analyzed, and the Markov process is applied to construct a transition probabilistic model. When a UE moves to an adjacent gNodeB in the 5G connection management-idle state,...
2016 Eighth International Conference on Ubiquitous and Future Networks (ICUFN), 2016
Many studies are based on automatic or semi-automatic measurement of various a priori brain Regio... more Many studies are based on automatic or semi-automatic measurement of various a priori brain Region of Interest (ROI) to compare and discriminate between healthy controls (HC) and Alzheimer Disease (AD) patients. The proposed diagnosis method results yield up to about 84% stratification accuracy with Multi-kernel SVM along with high sensitivity and specificity above 85%.
Journal of the Institute of Electronics Engineers of Korea, 2007
Streaming video is expected to become a key service in the developing heterogeneous wireless netw... more Streaming video is expected to become a key service in the developing heterogeneous wireless network. However, sufficient quality of service is not offered to video applications because of bursty packet losses. An effective solution for packet loss in wireless network is to perform a proper concealment at the receiver. However, most concealment methods can not conceal effectively the consecutively damaged macro blocks, since the neighboring blocks are lost. In the previous work, bidirectional motion vector tracking (BMVT) method has been proposed which uses the moving trajectory feature of the damaged macro blocks. In this paper, a channel-adaptive redundancy coding method for the better BMVT error concealment is presented. The proposed method provides enhanced video quality at the cost of a little bit overhead in the wireless error-prone network.
2018 52nd Asilomar Conference on Signals, Systems, and Computers, 2018
The Global Positioning System (GPS) is designed to accurately estimate the location information o... more The Global Positioning System (GPS) is designed to accurately estimate the location information of objects, using signals from at least four GPS satellites. When the high-power interference signals exist, the GPS receiver does not have the proper estimation performance. In this case, we need to enhance the desired GPS signals and to efficiently suppress interference signals. For this purpose, the adaptive beamformer based on the angle-of-arrival (AOA) is widely employed, but the AOA information of the GPS signal is not easily estimated. After conventional despreading, GPS AOA can be estimated using various AOA estimation algorithms such as Multiple Signal Classification (MUSIC), but the estimated result includes not only GPS AOA but also interference AOA at the high-power interference environment. In this paper, we propose a GPS AOA estimation algorithm, based on the composite despreader and the null despreader for multiple GPS signals. The AOA estimation result based on the composi...
Background : The time of arrival (TOA) trilateration is one of the representative location detect... more Background : The time of arrival (TOA) trilateration is one of the representative location detection technologies (LDT), which determines the true location of mobile station (MS) using a unique intersection point of three circles based on three radiuses corresponding to distances between MS and base stations (BSs) and center coordinates of BSs. Since the distance between MS and BS is estimated by using the number of time delays, three circles based on the estimated radiuses are generally increased and they may not meet at a single point, resulting in the location estimation error. Aim : In order to compensate this estimation error and to improve estimation performance, we present two advanced TOA trilateration localization algorithms with detail mathematical expressions. Materials and Methods : The considered algorithms are the shortest distance algorithm, which calculates an average of three interior intersection points among entire six intersection points from three intersecting c...
The Journal of The Korea Institute of Intelligent Transport Systems, 2008
Wireless sensor network-related application system can perform functions such as environmental po... more Wireless sensor network-related application system can perform functions such as environmental pollution monitoring, building control, home automation in future. In this paper, we present wireless sensor network based system for subway station in order to reduce the damage of the people and the subway station due to fire. Sensor nodes in this system can sense temperature, illumination, smoke, and human body in real time and detect the accident in the subway station. These real-time sensing and wireless networking minimize casualties and damage to property.
2018 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia), 2018
Recently indoor positioning system (IPS) has been getting a lot of attention. Similarly, because ... more Recently indoor positioning system (IPS) has been getting a lot of attention. Similarly, because of low cost and ease of use, Bluetooth low energy (BLE) is extensively used for IPS. Techniques such as trilateration, triangulation, and fingerprinting are widely studied in IPS. Fingerprinting is popular approach in RSSI based-IPS, but is also time-consuming method. Here, we proposed to use the state-of-the-art machine learning approach for fingerprinting. This paper proposes a BLE based machine learning location and tracking system for indoor positioning. The experimental results showed that the proposed method has an average estimation error of 50 cm.
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Papers by Jae-Young Pyun