Hyo Hyun Choi

Enhanced secure anonymous authentication scheme for roaming service in global mobility networks

Abstract User authentication scheme is an important issue for providing secure roaming service to users of mobile devices. In 2008, Wu, Lee and Tsaur proposed an enhanced anonymous authentication for roaming environment. In this paper, we show weaknesses of Wu–Lee–Tsaur’s schemes such as failing to achieve anonymity and perfect forward secrecy, and disclosing of legitimate user’s password. Therefore, we propose a new enhanced scheme that uses Elliptic Curve Diffie–Hellman (ECDH) to overcome these weaknesses and improve performance. We also demonstrate that our scheme not only overcomes these weaknesses but also provides mutual authentication and resistance to a man-in-the-middle attack. Compared with previous schemes that use public key cryptosystem with certificates, our scheme is more efficient. Moreover, our scheme does not use timestamps, so it is not required to synchronize the time.

Information delivery scheme of micro UAVs having limited communication range during tracking the moving target

In the proposed scheme, micro Unmanned Aerial Vehicle (micro UAV) is used to find the target and the UAV group is controlled to constantly provide location information to the base while the target is moving. UAVs have a limited communication range and information transmission is only possible through communication among the UAVs. After locating the target within the search area, the UAVs move toward the base station in order to transmit the information to the base station using multihop connectivity. In the proposed scheme, when communication is not possible among the UAVs because the target moves too far away from the base station, UAVs retain the information of the target and move toward the base station, deliver the information to another UAV, return to the target, and repeat the process. The base station calculates the range of target’s location upon receiving the information, and determines whether target tracking is possible with the current number of UAVs. The performance of the proposed scheme was evaluated by a simulation using NS-2.

EBBS: Energy-efficient BOP-based Beacon transmission Scheduling for WSNs

This paper describes an energy-efficient BOP-based beacon transmission scheduling (EBBS) algorithm. EBBS is the centralized approach, in which a resource-sufficient node called as Topology Management Center (TMC) allocates the time slots to transmit a beacon frame to the nodes and manages the active/sleep schedules of them. We also propose EBBS with Adaptive BOPL (EBBS-AB), to adjust the duration to transmit beacon frames in every beacon interval, adaptively. Simulation results show that by using the proposed algorithm, the energy efficiency and the throughput of whole network can be significantly improved. EBBS-AB is also more effective for the network performance when the nodes are uniformly deployed on the sensor field rather than the case of random topologies.

A heuristic resource scheduling scheme in time-constrained networks

Abstract Sensor device is emerging as a promising enabler for the development of new solutions in a plethora of Internet of Things (IoT) applications. With the explosion of connected devices, it is essential for conversion gateway between the Internet and sensor nodes to support end-to-end (e2e) interoperability because the current Internet Protocol (IT) does not support end-to-end delay in IEEE 802.15.4e. As part of IoT, we propose a scheduling scheme of multiple channels and multiple timeslots to minimize the e2e delay in multi-hop environments. The proposed greedy heuristic approach is compared with the meta-heuristics in terms of the given end-to-end delay bound. Although the meta-heuristics is more accurate in finding a global optimum or sub-optimal values than the greedy heuristic approach, this advantage comes at the expense of high complexity. The simulation results show that the proposed scheme reduces the complexity by obtaining suboptimal solutions that satisfy the e2e delay requirement.

An Obstacle Avoidance Scheme Maintaining Connectivity for Micro-Unmanned Aerial Vehicles

This paper suggests an obstacle avoidance scheme that enables a group of micro-UAV (Unmanned Aerial Vehicles) to avoid colliding with an obstacle that is found in the course of the flight. This scheme considers a method for UAVs to avoid colliding with such obstacles and a plan of action for when the UAVs in the group lose connectivity during flight. The main goal is for UAVs to reach the target without colliding with any obstacles. To achieve this goal, directly after the UAVs avoid the obstacle at a raised altitude above it, they fly at a higher altitude for a while and then descend to their original height. When this approach is judged to be inefficient because the height of the obstacle is too high, the UAVs divide into two groups and move to either side of it while continuing to fly at the same altitude, thereby avoiding the obstacle. Afterwards, they gather into one group again. We verify the proposed scheme and do the performance evaluation by ns-2.

Joint routing and scheduling in multi-channel capillary machine-to-machine networks

In recent times, machine-to-machine (M2M) communication is considered the most promising solution for revolutionizing future intelligent pervasive applications. The capillary M2M network is a key component of the M2M system, and it should support a data rate that is sufficient to accommodate various vertical applications with limited resources of end devices. This paper presents a joint routing and scheduling (JRS) framework for a capillary M2M network. To achieve the conflicting goals of maximizing network performance and conserving energy, the JRS framework is designed with an integrated concept of routing and transmission scheduling, which provides time division multiple access (TDMA)-based transmission scheduling based on the established routing path of data. Moreover, to extend the number of available transmission frames and enhance network performance, JRS uses the multi-channel communication approach. Experimental results of the prototype implementation demonstrate that JRS outperforms conventional schemes, even under heavy traffic conditions.

Two Tier Search Scheme Using Micro UAV Swarm

Herein, we propose a method for utilizing unmanned aerial vehicle (UAV) swarm when communication infrastructure is disabled due to war or natural disaster such as earthquake. The method involves using UAV swarm to perform a quick search, to locate the target by selecting main locations within the search area at which the target may be located, and to manipulate the swarm to establish continuous communication network to the base station. UAVs will first conduct the search of the whole area at high altitude to plan overall movement paths. They will then select N main locations within the searched area at which the target may be located, and divide into N groups to perform close search. The group that locates the target during the search will move toward the base station to transmit the information about the target, and the groups that did not locate the target also return to the base station. The groups that return to the base station receives information about the target then moves to the position between the target and the base station to maintain connectivity between the target and the base station. The proposed method was validated and its performance was evaluated using NS-2 simulation.

Queuing Analysis for IEEE 802.11e Networks in Non-Saturation Environments

This paper presents an analytical model for the performance evaluation of an IEEE 802.11e network in non-saturation environments. We first characterize the probability distribution of the MAC layer...

Energy-Efficient BOP-Based Beacon Transmission Scheduling in Wireless Sensor Networks

Many applications in wireless sensor networks (WSNs) require the energy efficiency and scalability. Although IEEE 802.15.4/Zigbee which is being considered as general technology for WSNs enables the low duty-cycling with time synchronization of all the nodes in network, it still suffer from its low scalability due to the beacon frame collision. Recently, various algorithms to resolve this problem are proposed. However, their manners to implement are somewhat ambiguous and the degradation of energy/communication efficiency is serious by the additional overhead. This paper describes an Energy-efficient BOP-based Beacon transmission Scheduling (EBBS) algorithm. EBBS is the centralized approach, in which a resource-sufficient node called as Topology Management Center (TMC) allocates the time slots to transmit a beacon frame to the nodes and manages the active/sleep schedules of them. We also propose EBBS with Adaptive BOPL (EBBS-AB), to adjust the duration to transmit beacon frames in every beacon interval, adaptively. Simulation results show that by using the proposed algorithm, the energy efficiency and the throughput of whole network can be significantly improved. EBBS-AB is also more effective for the network performance when the nodes are uniformly deployed on the sensor field rather than the case of random topologies.

Regional Density-aware Data Collection Using Unmanned Aerial Vehicle in Large-scale Wireless Sensor Networks

This paper presents a regional density-aware data collection (RDDC) using unmanned aerial vehicles (UAVs) in large-scale wireless sensor networks (WSNs). The RDDC is designed to support fast data collection by adaptively adjusting the value of the minimum contention window (CWmin) of the sensor nodes depending on the regional node density of sensing fields. The operation of RDDC consists of the region-partitioning, node-scanning, and data-collecting phases. In the region-partitioning phase, the RDDC partitions the sensing field into multiple regions and assigns a region ID to each sensor node according to the region to which it belongs. In the node-scanning phase, the RDDC calculates the node density of each region. Finally, in the data-collecting phase, the RDDC assigns different CWmin values to each sensor node considering the regional node density of each region. The experimental simulation results show that the RDDC obtains higher aggregate throughput and shorter delay than the existing data collection method.