• Title/Summary/Keyword: 무선 자원 관리

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The Channel Scheduler based on Water-filling Algorithm for Best Effort Forward Link Traffics in AMC/TDM/CDM System (AMC/TDM/CDM 다중접속방식에서의 Best Effort 순방향 서비스를 위한 Water-filling Based 채널 스케줄러)

  • Ma, Dongl-Chul;Ki, Young-Min;Kim, Dong-Ku
    • Journal of Advanced Navigation Technology
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    • v.7 no.1
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    • pp.59-71
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    • 2003
  • The channel scheduler is suggested the radio resource management method in order to provide service with guaranteeing fairness and throughput to the users who use limited wireless channel. Proportional fairness scheduling algorithm is the channel scheduler used in the AMC(Adaptive Modulation and Coding)/TDM system, and this algorithm increases the throughput considering the user's time fairness. In this paper is suggested the channel scheduler combining CDM scheme available in AMC/TDM/CDM system. Unlike the system which only uses TDM which provide the only one user at the same slot, this scheduler can service a lot of users since this uses the CDM scheme with multi-cord channel. At every moment, allocation of transmission power to multi-channel users is problematic because of CDM scheme. In this paper, we propose a water-filling scheduling algorithm to solve the problem. Water-filling fairness(WF2) scheduling algorithm watches the average channel environment. So, this modified method guarantees fairness for each user in terms of power and service time.

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State Machine Frameworks Operating in Sensor Network Operation System based on Multi-Thread (멀티쓰레드 기반 센서네트워크 운영체제에서 동작하는 상태머신 프레임워크)

  • Lee, Seung-Keun;Kim, Byung-Kon;Choi, Byoung-Kyu;Shin, Heu
    • The KIPS Transactions:PartA
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    • v.17A no.3
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    • pp.127-136
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    • 2010
  • A wireless sensor network(WSN) which roles as a mediator between living environment and computers in ubiquitous computing is very essential research area. Due to the constraint that sensor nodes should work in very resource-restricted circumstances, an operating system that can manage resources effectively is demanded. Also, a sensor network should be able to deal with many events quickly and simultaneously in order to respond to various physical changes in outer environment. The Sensor Network Operating System such as TinyOS, MANTIS and NanoQplus is much designed so that it can satisfy such requirement. But, for programmers who develop application program for sensor networks, they have lack of frameworks which the development is easily possible from restricted development environment. In this paper for this, we implemented a state machine framework apt for responsive systems in NanoQplus which is multi-thread-based sensor network operating system. In addition we propose an event broker module(EBM) for effective event dispatching, a message data structure for message sharing among state machines, and an execution module that handles messages and their queue and performs state transition of the machines. Furthermore, we could do the development more easily an application program with a state-based framework by developing CASE tools.

Development of the PC Based Color Fish Finder (퍼스널 컴퓨터를 이용한 칼라 어군탐지기의 개발에 관한 연구)

  • 신현옥
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.31 no.3
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    • pp.247-255
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    • 1995
  • This paper describes a personal computer(PC) based color fish finder to improve some problem of the commercial one. The commercial fish finder has no function of the echo data logging and replaying. The authors developed two types of the PC based color fish finder. One is a master type composed of a PC, a digital input-output board, and analog to digital converting (A/D) board and an ultrasonic transceiver unit, the other is a slave type composed of a PC and an A/D board. To test the performances of the master type experiments were carried out in air and in a water tank. It is found that the designed master type fish finder displays very well an eight-colored echogram by one dot resolution to the left side of the PC monitor. Also, the depth of echo signal was corresponds very well to the range from the transducer to a target. The sampling interval of echo signal is about 0.1m and the time of A/D conversion is 30 $\mu$sec. On the other hand, to test the performances of the slave type a raw data of echo signals from a data logger was supplied directly or via RF transceivers to the slave type one. From this experiment, it is confirmed the slave type is useful to replay the echo signal from the data logger or a telesounder.

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A TOA Shortest Distance Algorithm for Estimating Mobile Location (모바일 위치추정을 위한 TOA 최단거리 알고리즘)

  • Pradhan, Sajina;Hwang, Suk-Seung
    • The Journal of the Korea institute of electronic communication sciences
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    • v.8 no.12
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    • pp.1883-1890
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    • 2013
  • Location detection technology (LDT) is one of the core techniques for location based service (LBS) in wireless communication for improving resource management and quality of services. The location of a mobile station (MS) is estimated using the time of arrival (TOA) technique based on three circles with centers corresponding to coordinates of three base stations (BSs) and radius corresponding to distances between MS and BSs. For accurately estimating the location of MS, three circles should meet at a point for the trilateration method, but they generally do not meet a point because the radius is increased depending on the number of time delay for estimating the distance between MS and BS and the carrier frequency. The increased three circles intersect at six points and the three intersection points among them should be generally placed close to coordinate of the location for the specific MS. In this paper, we propose the shortest distance algorithm for TOA trilateration method, to select three interior intersection points from entire six points. The proposed approach selects three intersection points with the shortest distances between coordinates of MS and intersection points and determines the averaged coordinate of the selected three points, as the location of the specific MS. We demonstrate the performance of the proposed algorithm using a typical computer simulation example.

MAC Scheduling Algorithm for Efficient Management of Wireless Resources in Bluetooth Systems (블루투스 시스템에서의 효율적 무선자원관리를 위한 MAC 스케쥴링 기법)

  • 주양익;권오석;오종수;김용석;이태진;엄두섭;차균현
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.9A
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    • pp.702-709
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    • 2003
  • In this paper, we propose an efficient and QoS-aware MAC scheduling algorithm for Bluetooth, which considers both throughput and delay performance of each Master-Slave pair in scheduling decisions, and thus, attempts to maximize overall performance. The proposed algorithm, MTDPP (Modified Throughput-Delay Priority Policy), makes up for the drawbacks of T-D PP (Throughput-Delay Priority Policy) proposed in [6] and improves the performance. Since Bluetooth employs a master-driven TDD based scheduling algorithm, which is basically operated with the Round Robin policy, many slots may be wasted by POLL or NULL packets when there is no data waiting for transmission in queues. To overcome this link wastage problem, several algorithms have been proposed. Among them, queue state-based priority policy and low power mode-based algorithm can perform with high throughput and reasonable fairness. However, their performances may depend on traffic characteristics, i.e., static or dynamic, and they require additional computational and signaling overheads. In order to tackle such problems, we propose a new scheduling algorithm. Performance of our proposed algorithm is evaluated with respect to throughput and delay. Simulation results show that overall performances can be improved by selecting suitable parameters of our algorithm.

Habitat Characteristics of Myotis ikonnikovi (쇠큰수염박쥐(Myotis ikonnikovi)의 서식지 특성)

  • Kim, Sun-Sook;Fukui, Dai;Han, Sang-Hoon;Hur, Wee-Haeng;Oh, Dae-Shik
    • Korean Journal of Ecology and Environment
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    • v.47 no.1
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    • pp.41-52
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    • 2014
  • Little is known about foraging and roosting habitat of tree-roosting bats in Korea. In the present study, we studied on characteristics of foraging and roosting habitats by Ikonnikov's whiskered bats (Myotis ikonnikovi) in the South Korea, using trapping and radiotelemetry. We captured the bats at 15 sites during nights (foraging times) using mist-nets. Based on characteristic analyses of forests within a radius 500 m from each capture site, forests of M. ikonnikovi habitat are similar characteristics to the old-growth forests. They foraged at forests dominated by boradleaf stands which are older than than 30-year-old and thicker than 20 cm in diameter at breast height (DBH). We used radio-transmitters to locate and characterize day-roosts of Myotis ikonnikovi, and totally the roost use patterns of three bats were surveyed. They roosted in trees (both live and dead) with exfoliating bark, extensive vertical cracks, or cavities, and thier roosting sites were located about 500 m from the initial capture location. The bats had a number of roost in a short-distance, some used new roost every day and the same roost sometimes were used repeatedly. To increase the diversity of the tree-dwelling bats including Myotis ikonnikovi, management practices that the higher food and roost availablility can be sustained in forests are needed.

Cross-layer Design of Joint Routing and Scheduling for Maximizing Network Capacity of IEEE 802.11s based Multi-Channel SmartGrid NAN Networks (IEEE 802.11s 를 사용한 스마트그리드 NAN 네트워크의 최대 전송 성능을 위한 다중 채널 스케쥴링과 라우팅의 결합 설계)

  • Min, Seok Hong;Kim, Bong Gyu;Lee, Jae Yong;Kim, Byung Chul
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.25-36
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    • 2016
  • The goal of the SmartGrid is to maximize energy efficiency by exchanging bi-directional real-time power information with the help of ICT(Information and Communication Technology). In this paper, we propose a "JRS-MS" (Joint Routing and Scheduling for Multi-channel SmartGrid) algorithm that uses numerical modeling methods in IEEE 802.11s based STDMA multi-channel SmartGrid NAN networks. The proposed algorithm controls the amount of data transmission adaptively at the link layer and finds a high data-rate path which has the least interference between traffic flows in multi-channel SmartGrid NAN networks. The proposed algorithm improve transmission performance by enhancing network utilization. By comparing the results of performance analysis between the proposed algorithm and the JRS-SG algorithm in the previous paper, we showed that the JRS-MS algorithm can improve transmission performance by maximally utilizing given network resources when the number of flows are increasing in the multi-hop NAN wireless mesh networks.

Performance Analysis of AAL2 Packet Dropping Algorithm using PDV on Virtual Buffer (PDV를 이용한 가상 버퍼상의 AAL2 패킷 폐기 알고리즘과 성능분석)

  • Jeong, Da-Wi;Jo, Yeong-Jong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.39 no.1
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    • pp.20-33
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    • 2002
  • Usage of ATM AAL2 packets becomes dominant to increase transmission efficiency of voice traffic in the backbone network. In case of voice service that uses AAL2 mechanism, if resources of network are enough, connection of new call is accepted. However, due to packets generated by the new call, transmission delay of packets from old calls can increase sharply. To control this behavior, in this paper we present an AAL2 buffer management scheme that allocates a virtual buffer to each call and after calculating its propagation delay variation(PDV), decides to drop packets coming from each call according to the PDV value. We show that this packet dropping algorithm can effectively prevent abrupt QoS degradation of old calls. To do this, we analyze AAL2 packet composition process to find a critical factor in the process that influences the end-to-end delay behavior and model the process by K-policy M/D/1 queueing system and MIN(K, Tc)-policy M/D/1 queueing system. From the mathematical model, we derive the probability generating function of AAL2 packets in the buffer and mean waiting time of packets in the AAL2 buffer. Analytical results show that the AAL2 packet dropping algorithm can provide stable AAL2 packetization delay and ATM cell generation time even if the number of voice sources increases dramatically. Finally we compare the analytical result to simulation data obtained by using the COMNET Ⅲ package.

A Fast Global Mobility Supporting Scheme for IPv6 Using Global Mobility Agent (GMA) (Global Mobility Agent (GMA) 기반의 신속한 IPv6 전역 이동성 지원 방안)

  • Ahn, Jin-Su;Seo, Won-Kyeong;Choi, Jae-In;Cho, You-Ze
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.8B
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    • pp.1105-1114
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    • 2010
  • The Proxy Mobile IPv6 (PMIPv6) has been standardized by the IETF NETLMM WG for network-based mobility management. The PMIPv6 can provide IP mobility for Mobile Nodes (MNs) with low handover latency and less wireless resource usage. But, since the PMIPv6 is basically designed for local mobility management, it cannot support directly global mobility management between different PMIPv6 domains. In the PMIPv6, since all traffic is routed through a Local Mobility Anchor (LMA), it causes a long end-to-end delay and triangular routing problem. Therefore, in this paper, we propose a fast network-based global mobility management scheme and route optimization scheme with a new network entity, called Global Mobility Agent (GMA). Numerical analysis and simulation results show that the proposed scheme is able to support global mobility between different public domains with low handover latency and low end-to-end delay, compared with the PMIPv6.