• Title/Summary/Keyword: 무선전력전송

Search Result 1,152, Processing Time 0.027 seconds

A Backup Node Based Fault-tolerance Scheme for Coverage Preserving in Wireless Sensor Networks (무선 센서 네트워크에서의 감지범위 보존을 위한 백업 노드 기반 결함 허용 기법)

  • Hahn, Joo-Sun;Ha, Rhan
    • Journal of KIISE:Information Networking
    • /
    • v.36 no.4
    • /
    • pp.339-350
    • /
    • 2009
  • In wireless sensor networks, the limited battery resources of sensor nodes have a direct impact on network lifetime. To reduce unnecessary power consumption, it is often the case that only a minimum number of sensor nodes operate in active mode while the others are kept in sleep mode. In such a case, however, the network service can be easily unreliable if any active node is unable to perform its sensing or communication function because of an unexpected failure. Thus, for achieving reliable sensing, it is important to maintain the sensing level even when some sensor nodes fail. In this paper, we propose a new fault-tolerance scheme, called FCP(Fault-tolerant Coverage Preserving), that gives an efficient way to handle the degradation of the sensing level caused by sensor node failures. In the proposed FCP scheme, a set of backup nodes are pre-designated for each active node to be used to replace the active node in case of its failure. Experimental results show that the FCP scheme provides enhanced performance with reduced overhead in terms of sensing coverage preserving, the number of backup nodes and the amount of control messages. On the average, the percentage of coverage preserving is improved by 87.2% while the additional number of backup nodes and the additional amount of control messages are reduced by 57.6% and 99.5%, respectively, compared with previous fault-tolerance schemes.

Rectifier with Comparator Using Unbalanced Body Biasing to Control Comparing Time for Wireless Power Transfer (비대칭 몸체 바이어싱 비교기를 사용하여 비교시간을 조절하는 무선 전력 전송용 정류기)

  • Ha, Byeong Wan;Cho, Choon Sik
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.24 no.11
    • /
    • pp.1091-1097
    • /
    • 2013
  • This paper presents a rectifier with comparator using unbalanced body biasing in $0.11{\mu}m$ RF CMOS process. It is composed of MOSFETs and two comparators. The comparator is used to reduce reverse leakage current which occurs when the load voltage is higher than input voltage. For the comparator, unbalanced body biasing is devised. By using unbalanced body biasing, reference voltage for comparator changing from high state to low state is increased, and it reduces time interval for leakage current to flow. 13.56 MHz 2 Vpp signal is used for input and $1k{\Omega}$ resistor and 1 nF capacitor are used for output load for simulation and experimental environment. In simulation environment, voltage conversion efficiency(VCE) is 87.5 % and Power conversion efficiency(PCE) is 50 %. When the rectifier is measured, VCE shows 90.203 % and PCE shows 45 %.

A New Congestion Control Algorithm for Vehicle to Vehicle Safety Communications (차량 안전 통신을 위한 새로운 혼잡 제어 알고리즘 제안)

  • Yi, Wonjae
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.5
    • /
    • pp.125-132
    • /
    • 2017
  • Vehicular safety service reduces traffic accidents and traffic congestion by informing drivers in advance of threats that may occur while driving using vehicle-to-vehicle (V2V) communications in a wireless environment. For vehicle safety services, every vehicle must broadcasts a Basic Safety Message(BSM) periodically. In congested traffic areas, however, network congestion can easily happen, reduce the message delivery ratio, increase end-to-end delay and destabilize vehicular safety service system. In this paper, to solve the network congestion problem in vehicle safety communications, we approximate the relationship between channel busy ratio and the number of vehicles and use it to estimate the total network congestion. We propose a new context-aware transmit power control algorithm which controls the transmission power based on total network congestion. The performance of the proposed algorithm is evaluated using Qualnet, a network simulator. As a result, the estimation of total network congestion is accurately approximated except in specific scenarios, and the packet error rate in vehicle safety communication is reduced through transmit power control.

Communication Module Selection Algorithm for Energy Saving of Smartphone (스마트폰 에너지 절감을 위한 통신모듈 선택 알고리즘)

  • Lee, Chang-Moo;Lee, Seung-Jae;Choi, Deok-Jai
    • The Journal of the Korea Contents Association
    • /
    • v.12 no.5
    • /
    • pp.22-31
    • /
    • 2012
  • A Smartphone is an intelligent device combined mobile phone and pc's support functions, and can perform multiple functions to satisfy the demands of users. It has excellent processing power and communication modules(DMB, Wi-Fi, Bluetooth, NFC etc) to carry out the demands of users. But continuous using of battery power on processor and equipped modules causes acceleration of battery consumption. This means that effective power management in devices like smartphone is important. Therefore, the management of power consumption on system execution and communication module is a serious issue in this field of study. In this paper, we would like to propose a communication module selection algorithm based on energy consumption parameter of each communication module and data transfer time. Our scheme automatically select appropriate communication system to reduce high energy consumption on bluetooth sleep mode so that this scheme is more efficient and effective thus improving user convenience in longer usage time. Experimental results showed the 20% energy saving.

Effect of SIC Errors to Cooperative NOMA systems (SIC 에러가 협동 NOMA 시스템에 미치는 영향)

  • Kim, Nam-Soo
    • The Journal of the Institute of Internet, Broadcasting and Communication
    • /
    • v.17 no.5
    • /
    • pp.35-42
    • /
    • 2017
  • NOMA (Non-orthogonal multiple access) system is the most promising multiple access technology to satisfy the requirements of the spectral efficiency and the performance of 5G cellular systems. NOMA system simultaneously serves multiple users in the power domain, and adapts SIC (Successive interference cancellation) at the receivers to cancel the interference from multiple users. Since in a realistic wireless fading channel the perfect SIC is impossible, the study of the effect of the imperfect SIC to a NOMA system is necessary. This paper considers a cooperative NOMA system with SIC error, and the performance of the system is analytically derived. And the optimum power allocation to minimize the system performance is obtained. When the transmit power is fixed, the distances between a base station and the relay is considered for different SIC errors. The derived analytical results are verified through Monte Carlo simulation, and the results are perfectly matched.

A Threshold based Connectivity Enhancement Scheme for Mobile Ad-hoc Networks (MANET에서 경로 연속성 증대방안에 대한 연구)

  • Jang Yunchul;Park Sangioon;Kim Byunggi
    • Journal of KIISE:Information Networking
    • /
    • v.32 no.2
    • /
    • pp.215-219
    • /
    • 2005
  • Generally, the mobile nodes in MANET have the limited power capacity available for actual communications. Thus, the power management is very important for packet routing or forwarding. Although MTPR, MBCR and MMBCR are proposed to treat the problem of power consumption, there have been few researches resolving the link breakdown that is occurred by the power exhaustion during transmission. In this sense, the reliable scheme should be required to ensure the routing connectivity. In this paper, we propose three schemes to enforce the routing connectivity. If the signal strength is dropped below a signal threshold, the candidate route is previously selected to prepare the link breakdown. Also, on multi-channel, we propose the lifetime increment scheme of a node that it manage its available power to the needed power of a new link. The simulation results show the enforcement of the link connectivity and the performance improvements of the delay time through the effective connection management.

Design of a Trackable Buoy System using Join Request Messages (가입요청 메시지를 사용하는 추적 가능한 부표 시스템의 설계)

  • Cho, SungHo
    • Journal of Satellite, Information and Communications
    • /
    • v.11 no.2
    • /
    • pp.8-13
    • /
    • 2016
  • A buoy is a float attached by chain to the seabed to mark channels in a harbor or underwater hazards and can be classified into two major types as autonomous buoys and fixed buoys. When there is high demand such as marking channels in a harbor, monitoring ecology of ocean and environmental monitoring of coastal areas, smart buoys are developed. The smart buoys have wireless network systems such as GPS, CDMA and ZigBee. Using the GPS techniques, location and environments of buoy can be monitored and traced. However, the GPS in fixed buoy systems has a high power consumption and cost. Using many buoys on low power ZigBee basis allows dramatic reduction of the overall power consumption. In this study, it is aimed at the design of the trackable protocol for a buoy system which has low data rate and low power consumption. The proposed protocol has advantages that it can detect abnormal movement and gather trackable information without any system changes. In the introduced protocol, additional 2 bits and join request messages are used for trackable buoy system. The behaviors of improved protocol is modeled into petri-net and proved a reachability.

Improved Power Allocation to Enhance the Capacity in OFDMA System for Proportional Resource Allocation (Proportional 자원할당을 위한 OFDMA 시스템에서 채널 용량을 증대시키기 위한 향상된 전력 할당 기법)

  • Var, Puthnith;Shrestha, Robin;Kim, JaeMoung
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.38A no.7
    • /
    • pp.580-591
    • /
    • 2013
  • The Orthogonal Frequency Division Multiple Access (OFDMA) is considered as a novel modulation and multiple access technique for 4th generation wireless systems. In this paper, we formulate a base station's power allocation algorithm for each user to maximize the user's sum rate, subject to constraints on total power, bit error rate, and rate proportionality among the users for a better proportional rate adaptive (RA) resource allocation method for OFDMA based system. We propose a novel power allocation method based on the proportion of subcarrier allocation and the user's normalized proportionality constant. We adapt a greedy algorithm and waterfilling technique for allocating the subcarriers among the users. In an end-to-end simulation, we validate that the proposed technique has higher system capacity and lower CPU execution times, while maintaining the acceptable rate proportionality among users.

Implementation of Smart Shoes for Dementia Patients using Embedded Board and Low Power Wide Area Technology (저전력장거리 기술과 임베디드 보드를 이용한 치매 돌봄 스마트 신발 구현)

  • Lee, Sung-Jin;Choi, Jun-Hyeong;Seo, Chang-Sung;Park, Byung-Kwon;Choi, Byeong-Yoon
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.24 no.1
    • /
    • pp.100-106
    • /
    • 2020
  • In this paper smart shoes for dementia care using embedded boards and Low Power Wide Area technology and their application software are implemented. The communication board composed of Cortex-M3 board and LoRa module is embedded into groove made in outsole of smart shoes. Including the mold, the shoe outsole was manufactured by hand. By using application software and embedded board, caregiver can track the position of dementia patient using GPS and LoRa network. The location tracking and data transmission operations of smart shoes have been successfully verified in the outdoor environment. The smart shoes of this paper are applicable to a safety device to prevent the disappearance of demented patients through results of experiments and if bigdata is collected and analyzed by deep-learning, it may be helpful to analyze the predictive path of dementia patients or the pattern of dementia.

Task offloading scheme based on the DRL of Connected Home using MEC (MEC를 활용한 커넥티드 홈의 DRL 기반 태스크 오프로딩 기법)

  • Ducsun Lim;Kyu-Seek Sohn
    • The Journal of the Institute of Internet, Broadcasting and Communication
    • /
    • v.23 no.6
    • /
    • pp.61-67
    • /
    • 2023
  • The rise of 5G and the proliferation of smart devices have underscored the significance of multi-access edge computing (MEC). Amidst this trend, interest in effectively processing computation-intensive and latency-sensitive applications has increased. This study investigated a novel task offloading strategy considering the probabilistic MEC environment to address these challenges. Initially, we considered the frequency of dynamic task requests and the unstable conditions of wireless channels to propose a method for minimizing vehicle power consumption and latency. Subsequently, our research delved into a deep reinforcement learning (DRL) based offloading technique, offering a way to achieve equilibrium between local computation and offloading transmission power. We analyzed the power consumption and queuing latency of vehicles using the deep deterministic policy gradient (DDPG) and deep Q-network (DQN) techniques. Finally, we derived and validated the optimal performance enhancement strategy in a vehicle based MEC environment.