• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4188-4206
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• 2016

Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.651-659
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• 2014

In this paper, we consider a two way relay network for ship-to-ship communications in a fleet, where two communicating ships exchange the information with the help of a multi-antenna relay ship. For the network, we propose a rate-aware three-phase analog network coding to improve the reliability of the information exchange with asymmetric rates. The proposed scheme allows low-complex implementation of the relay without channel estimation by generating an improved analog network coded signal with the orthogonally received signals from two ships by using only the received signal power at each antenna. In addition, the proposed scheme reduces outages in the data exchange at asymmetric rates by adopting a rate-aware relay power allocation, which is confirmed by evaluating the outage performance via simulation.

• Journal of Internet Computing and Services
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• v.5 no.2
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• pp.75-84
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• 2004

Geocasting, a variant of the conventional multicasting problem, is one of communication type in which the data packets are delivered to a group of all nodes within a specified geographical region (i.e., the geocasting region) and is called location-based multicasting(LBM)(l). An Ad-hoc network is a dynamically reconfigurable and temporary wireless network where all mobile devices using batteries as energy resources cooperatively maintain network connectivity without central administration or the assistance of base stations. Consequently, the technique to efficiently consume the limited amounts of energy resources is an important problem so that the system lifetime is maximized. In this paper, we propose a LBPA(Location-Based Power Aware) geocasting algorithm that selects energy-aware neighbor to route a packet towards the target region In Ad-hoc network environments. The method Is such that the energy consumption is balanced among the nodes in proportion to their energy reserves. Through the simulations, the proposed LBPA algorithm shows better results, that is, as good as 40% on the average over the conventional LBM algorithm in terms of the network lifetime.

• ETRI Journal
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• v.37 no.1
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• pp.118-127
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• 2015

The power consumption of 3D many-core processors can be reduced, and the power delivery of such processors can be improved by introducing voltage island (VI) design using on-chip voltage regulators. With the dramatic growth in the number of cores that are integrated in a processor, however, it is infeasible to adopt per-core VI design. We propose a 3D many-core processor architecture that consists of multiple voltage clusters, where each has a set of cores that share an on-chip voltage regulator. Based on the architecture, the steady state temperature is analyzed so that the thermal characteristic of each voltage cluster is known. In the voltage scaling and task scheduling stages, the thermal characteristics and communication between cores is considered. The consideration of the thermal characteristics enables the proposed VI formation to reduce the total energy consumption, peak temperature, and temperature gradients in 3D many-core processors.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.1
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• pp.25-29
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• 2008

In this paper, we provide an adaptive power-aware checkpointing scheme for fixed priority-based DVS scheduling in dependable real-time systems. In the provided scheme, we analyze the minimum number of tolerable faults of a task and the optimal checkpointing interval in order to meet the deadline and guarantee its specified reliability. The energy-efficient voltage level at a fault arrival is also analyzed and used in the recovery of the faulty task.

• Annual Conference of KIPS
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• 2011.11a
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• pp.177-180
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• 2011

In practice, it is well known that geographical and/or location based routing is highly effective for wireless sensor network. Here, electing some landmarks on the network and forwarding data based on the landmark is one of the good approaches for a vast sensing field with holes. In the most previous works, landmarks are elected without considering the residual energy on each sensor. In this paper, we propose an Energy aware Landmark Election and Routing (ELER) protocol to establish a stable routing paths and reduce the total power consumption. The proposed protocol makes use of each sensor's energy level on electing the landmarks, which would be utilized to route a packet towards the target region using greedy forwarding method. Our simulation results illustrate that the proposed scheme can significantly reduce the power dissipation and effectively lengthen the lifetime of the network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7B
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• pp.578-585
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• 2012

Location tracking system through GPS and Wi-Fi is available at no additional cost in an environment of IEEE 802.11-based wireless network. It is useful for many applications in outdoor environment. However, a previous systems used for general device to tag. It is unsuitable for power aware location tracking system because general devices is more expensive and non-optimized for tracking. The hand-off method of IEEE 802.11 standard is not enough considering power consumption. This thesis analyzes the previous location tracking systems and proposes power aware system. First, we designed and implemented tag to optimize location tracking. Next, we propose low-power hand-off method and low-power behavior model in implemented tag. The proposed hand-off method resolve power problem by using the location information and behavior model minimize power consumption of tag through power-saving mode and the concept of duty cycle. To evaluating proposed methods and system performance, we perform simulations and experiments in real environment. And then, we calculate tag's power consumption based on the actual measured current consumption of each operation. In a simulation result, the proposed behavior model and hand-off method reduced about 98%, 59% than the standard's hand-off and default behavior model.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.9-17
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• 2020

Mobile robots, including UAVs perform missions with limited fuel. Therefore, the energy-aware path planning is required to maximize efficiency when the robot is operated for a long time. In this study, we estimated the power consumption for each maneuver of a quadcopter UAV in the 3D environment and applied to the cost functions of D^⁎ Lite. The simulations were performed in a 3D environment that is similar to the industrial sites. The efficiency of path generation was high when the energy-aware path planning with simplified heuristic was applied. In addition, the energy-aware path was generated 19.3 times faster than the shortest path with a difference within 3.2%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1799-1805
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• 2007

Wireless Ad-hoc networks may contain nodes of various types of which many can have limited power capabilities. A failure of a node due to energy exhaustion may impact the performance of the whole network hence, energy must be conserved. In this paper, we propose a Delay and Energy-Aware Routing (DEAR) algorithm a multiple metric path cost routing algorithm which considers not only the energy consumed by the node during transmission and reception but as well as the residual energy of the node and the delay incurred during route discovery. Based on our results, DEAR algorithm performs well and maximizes network lifetime by routing flows to nodes with sufficient energy such that the energy consumption is balanced among nodes in proportion to their energy reserves.

• ETRI Journal
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• v.44 no.5
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• pp.746-758
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• 2022

This paper focuses on a mobile edge-computing-enabled heterogeneous network. A battery level-aware task-scheduling framework is proposed to improve the energy efficiency and prolong the operating hours of battery-powered mobile devices. The formulated optimization problem is a typical mixed-integer nonlinear programming problem. To solve this nondeterministic polynomial (NP)-hard problem, a decomposition-based task-scheduling algorithm is proposed. Using an alternating optimization technology, the original problem is divided into three subproblems. In the outer loop, task offloading decisions are yielded using a pruning search algorithm for the task offloading subproblem. In the inner loop, closed-form solutions for computational resource allocation subproblems are derived using the Lagrangian multiplier method. Then, it is proven that the transmitted power-allocation subproblem is a unimodal problem; this subproblem is solved using a gradient-based bisection search algorithm. The simulation results demonstrate that the proposed framework achieves better energy efficiency than other frameworks. Additionally, the impact of the battery level-aware scheme on the operating hours of battery-powered mobile devices is also investigated.