• Journal of the Korea Society of Computer and Information
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• v.23 no.9
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• pp.43-50
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• 2018

In this paper, we propose a hexagon model-based efficient beacon frame scheduling approach for wireless sensor networks. The existing beacon frame scheduling approaches use a lot of slots and subslots for the beacon frame scheduling. Thus, the data from source nodes are not efficiently delivered to a sink node. Also in case a sink node needs to broadcast a beacon frame to the nodes in the network, delivering the beacon frame to the network nodes is not efficient as well. Thus, to solve the problem, we use a hexagon model to find the number of slots and subslots for the beacon frame scheduling. By using them for the beacon frame scheduling, the proposed approach performs better than other approaches in terms of the data transmission delay, the number of received data, the beacon transmission delay and the number of relaying the beacon frames.

• Journal of Information Processing Systems
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• v.11 no.2
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• pp.295-309
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• 2015

Beacon scheduling is considered to be one of the most significant challenges for energy-efficient Low-Rate Wireless Personal Area Network (LR-WPAN) multi-hop networks. The emerging new standard, IEEE802.15.4e, contains a distributed beacon scheduling functionality that utilizes a specific bitmap and multi-superframe structure. However, this new standard does not provide a critical recipe for superframe duration (SD) allocation in beacon scheduling. Therefore, in this paper, we first introduce three different SD allocation approaches, LSB first, MSB first, and random. Via experiments we show that IEEE802.15.4e DSME beacon scheduling performs differently for different SD allocation schemes. Based on our experimental results we propose an adaptive SD allocation (ASDA) algorithm. It utilizes a single indicator, a distributed neighboring slot incrementer (DNSI). The experimental results demonstrate that the ASDA has a superior performance over other methods from the viewpoint of resource efficiency.

• The Journal of Society for e-Business Studies
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• v.15 no.4
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• pp.49-58
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• 2010

The wireless sensor network technology becomes one of core technologies to make it possible to implement various e-business applications. Energy efficiency is an important issue in wireless sensor networks. IEEE 802.15.4, a representative international standard for wireless sensor networks, provides the beacon enabled mode for energy-efficient communication. However, the beacons may conflict each other when the network is of multi-hop topology such as mesh or cluster-tree topology with beacon-enabled mode. The beacon conflict causes the failure of synchronization between sensor nodes, and affects other nodes in the network in that unsynchronized nodes cannot participate in communication. In this paper, we suggest an energy-efficient beacon scheduling for the wireless sensor networks. Nodes can save their energy duringperiod and prevent beacon conflict using beacon scheduling. We implement the scheduling using QualNet, and evaluate the performance under mesh topology networks. It turns out that the proposed scheduling may improve the energy efficiency in the networks.

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.19-28
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• 2011

The safety applications based on the IEEE 802.11p, periodically transmit the safety-related information to all surrounding vehicles with high reliability and a strict timeline. However, due to the high vehicle mobility, dynamic network topology and limited network resource, the fixed beacon scheduling scheme excess delay and packet loss due to the channel contention and network congestion. With this motivation, we propose a novel beacon scheduling algorithm referred to as spatial-aware(SA) beacon scheduling based on the spatial context information, dynamically rescheduling the beaconing rate like a TDMA channel access scheme. The proposed SA beacon scheduling algorithm was evaluated using different highway traffic scenarios with both a realistic channel model and 802.11p model in our simulation. The simulation results showed that the performance of our proposed algorithm was better than the fixed scheduling in terms of throughput, channel access delay, and channel load. Also, our proposed algorithm is satisfy the requirements of vehicular safety application.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.107-114
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• 2017

In beacon-enabled mode, beacon collision is a significant problem for the scalability of cluster-tree wireless sensor networks. In this paper, multi-channel time division scheduling (MCTS) is proposed to prevent beacon collisions and provide scalability. A coordinator broadcasts a beacon frame, including information on allocated channels and time-slots, and a new node determines its own channel and time-slot. The performance of the proposed method is evaluated by comparing the proposed approach with a typical ZigBee. MCTS prevents beacon collisions in cluster-tree wireless sensor networks. It enables large-scale wireless sensor networks based on a cluster tree to be scalable and effectively constructed.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.5
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• pp.433-439
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• 2010

This paper proposes a beacon color code scheduling algorithm for the localization of multiple robots in a multi-block workspace. With the developments of intelligent robotics and ubiquitous technology, service robots are applicable for the wide area such as airports and train stations where multiple indoor GPS systems are required for the localization of the mobile robots. Indoor localization schemes using ultrasonic sensors have been widely studied due to its cheap price and high accuracy. However, ultrasonic sensors have some shortages of short transmission range and interferences with other ultrasonic signals. In order to use multiple robots in wide workspace concurrently, it is necessary to resolve the interference problem among the multiple robots in the localization process. This paper proposes an indoor localization system for concurrent multiple robots localization in a wide service area which is divided into multi-block for the reliable sensor operation. The beacon color code scheduling algorithm is developed to avoid the signal interferences and to achieve efficient localization with high accuracy and short sampling time. The performance of the proposed localization system is verified through the simulations and the real experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3B
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• pp.255-263
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• 2009

In this paper, we propose an adaptive beacon scheduling algorithm to control a reception period of actual data according to variation of amount of traffic in IEEE 802.15.4 LR-WPAN(Low Rate-Wireless Personal Area Network) with the cluster-tree topology. If a beacon interval is shortened, the amount of the traffic a node receives can be increased while consumption of the energy can be also increased. In this sense, we can achieve optimal on orgy consumption by controlling the beacon interval when the amount of data to be received is being decreased. The result of simulation using NS-2 shows that the proposed algorithm improves performances in terms of packet loss rate and end-to-end delay compared with algorithm using a fixed beacon interval. For a design of cluster-tree based LR-WPAN managing delay-sensitive services, the proposed algorithm and the associated results can be applied usefully.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.625-630
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• 2006

Zigbee 센서 네트워크에서는 multihop 전송을 위하여 tree topology와 beacon-enabled 네트워크 구성을 갖는다. 이러한 multihop beaconing 네트워크의 목적은 routing 노드들에게 Sleep할 기회를 주어 파워의 소모를 줄이고자 하는 데 있다. 파워의 소모를 줄이고 beacon 전송시의 충돌을 방지하기 위하여 beacon 전송 스케줄링이 필요한데 본 논문은 multihop을 지원하고 에너지 효율에 효과적인 beacon 전송 스케줄링 알고리즘과 이를 바탕으로 에너지 효율적인 라우팅 기법을 제안한다. 본 제안은 Zigbee coordinator의 beacon interval(BI)이 결정되면 네트워크 내의 beacon을 전송하는 모든 노드들은 Zigbee coordinator의 BI를 알고 모든 노드의 superframe duration(SD)은 동일하다고 가정한다. 이러한 가정하에서 beacon을 전송하는 노드들이 Zigbee coordinator의 BI 구간 중 항상 정해진 시간에 자신의 beacon을 전송한다면 beacon의 충돌을 막을 수 있음을 보여 준다. 또한 노드들이 서로의 beacon 전송 시간을 알 수 있기 때문에 목적지 노드의 beacon을 tracking하지 않고도 목적지 노드가 active 되는 시점에 패킷을 전송하면 에너지 측면에서 좀 더 효율적인 라우팅 기반을 제공한다는 것을 보여 준다.

• Information and Communications Magazine
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• v.23 no.12
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• pp.17-36
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• 2006

본 고에서는 U-City를 구현할 때 가장 핵심적인 부가 서비스를 제공할 수 있는 서비스의 종류를 소개하고 이 서비스들이 필요로 하는 공통적인 요구사항을 정리한 후 이 서비스 구현에 적용 가능한 근거리 무선 통신 기술로서 최적의 프로토콜인 WiBEEM (Wireless Beacon-enabled Energy Efficient Mesh Network) 기술에 대해 소개하였다. WiBEEM 기술은 정보통신부가 추진한 IT 839 정책 중에서 핵심 인프라기술로 인정받고 있는 USN(Ubiquitous Sensor Network)을 위한 최적의 아키텍처로, Mesh Network를 구현 시 Bluetooth나 ZigBee 기술이 해결하지 못하는 다양한 문제점들을 해결하기 위해 여러 개의 Beacon을 수용하는 새로운 Superframe 구조를 제안하였으며 여러 개의 비컨들이 충돌없이 네트워크 정보를 전송할 수 있는 최적의 Beacon Scheduling 기법을 채택하였다. 또한 WiBEEM 기술은 기기의 이동성을 제공해 주기 위해 LAA (Last Address Assigned) 기법을 이용한 새로운 Short Address 할당 기법을 채택함으로써 16-bit 주소 공간을 낭비 없이 사용할 수 있게 하였으며 이동하는 기기와의 정보 전송을 위해 고속의 Routing 기법을 제공하는 USN 최적의 아키텍처이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1338-1345
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• 2014

Recently, wireless technology gains attention for industrial networks due to low cost, flexibility, relatively easy installation and most importantly, solving the rouring issue. ISA100.11a is one of promising standard for wireless industrial networks (WINs). Data traffic in industrial networks are known to be periodic and must satisfy the real-time property namely deadline. Therefore, in this paper, we proposed to apply deadline monotonic scheduling to periodic tasks in ISA100.11a networks and to evaluate the performance of ISA100.11a by checking the schedulability and beacon frame overhead. Simulation results showns, that our proposed scheme can reduces the network overhead while maintaining schedulability as compared to the previous algorithm. In addition, by reducing the network overhead, our proposed scheme can send more data without degrading the overall performance of WINs.