• The Magazine of the IEIE
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• v.34 no.3 s.274
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• pp.63-71
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• 2007

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.21 no.8
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• pp.86-92
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• 2003

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.21 no.8
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• pp.93-102
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• 2003

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2451-2456
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• 2010

As the recent development of mobile technology, users want to multi-service in anytime, anywhere, any terminal. To meet the needs of users, it causes a lot of expense that redesign of the entire network or expand the network of services areas. Therefore, IEEE, IETF is offering Handover technology between heterogeneous network. In this paper, the IEEE 802.21 MIH information server is based on the network. It proposes an improved handover that L3 layer to optimize the handover process use of FMIPv6 and executes simulation.

• Electronics and Telecommunications Trends
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• v.21 no.6 s.102
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• pp.202-211
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• 2006

본 논문에서는 2.4GHz 마그네트론을 이용하는 RF 전구에 대하여 동 대역을 사용하는IEEE 802.11b 기반의 무선랜과 전파간섭을 분석하였다. RF 전구가 무선랜에 미치는 전파간섭을 분석한 결과, LOS 환경(무선랜 수신전력 -63dBm/MHz)에서는 무선랜 채널 9, 10에 약 1~2Mbps의 전송속도 저하를 유발하였으며, Non-LOS 환경(무선랜 수신전력 -78dBm/MHz)에서는 무선랜 채널 6-11번에 통화절단 현상을 야기하였다. 그러나, RF 전구 수에 따른 간섭전력의 누적효과는 없는 것으로 나타났다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.3-9
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• 2011

In this paper, we propose workload partitioning methods in parallelizing AES-CCM which is proposed as the wireless encryption and message integrity standard IEEE 802.11i. In parallelizing AES-CCM having data dependency, synchronizations among processors are required, and multi-core processors have a very large range of synchronization performance. We propose and compare the performance of various workload partitioning methods by considering both the computational characteristics of AES-CCM and the synchronization overhead.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.4
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• pp.385-390
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• 2015

Quay cranes are considered core equipment for container terminal operation. However, unmanned operation systems have not as yet been announced due to the technological difficulties of implementation. In this paper, we developed a wireless controller to control a quay crane simulator remotely and conducted its performance test, a first step toward unmanned operation of quay cranes. The communication delay of a developed wireless controller was about 9.4ms on average while that of existing wired controllers was about 5.6ms. The same functions were implemented and tested on a smart phone where the average communication delay was 7.3ms. In addition, to apply the developed system into a real environment, we proposed a network architecture based on IEEE 802.11ac and carried out its performance evaluation. When the distance between two nodes was 50m apart, the throughputs of the TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) were 57Mbps and 189Mbps, respectively. The communication delay of the control data was 9.1ms through the TCP channel. These results reveal the proper working of remote quay crane operation if we adopt the IEEE 802.11ac network.

• International Journal of Computer Science & Network Security
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• v.23 no.4
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• pp.156-165
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• 2023

IEEE 802.15.4e-TSCH is recognized as a wireless industrial sensor network standard used in IoT systems. To ensure both power savings and reliable communications, the TSCH standard uses techniques including channel hopping and bandwidth reserve. In TSCH mode, scheduling is crucial because it allows sensor nodes to select when data should be delivered or received. Because a wide range of applications may necessitate energy economy and transmission dependability, we present a distributed approach that uses a cluster tree topology to forecast scheduling requirements for the following slotframe, concentrating on the Poisson model. The proposed Optimized Minimal Scheduling Function (OMSF) is interested in the details of the scheduling time intervals, something that was not supported by the Minimal Scheduling Function (MSF) proposed by the 6TSCH group. Our contribution helps to deduce the number of cells needed in the following slotframe by reducing the number of negotiation operations between the pairs of nodes in each cluster to settle on a schedule. As a result, the cluster tree network's error rate, traffic load, latency, and queue size have all decreased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.6
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• pp.10-21
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• 2010

In the cluster-tree network which covers wide area network and has many nodes for monitoring purpose traffic is concentrated around the sink. There are long transmit delay and high data loss due to the intensive traffic when IEEE 802.15.4 is adapted to the cluster-tree network. In this paper we propose Dynamic Channel Allocation algorithm which dynamically allocates channels to increase the channel usage and the transmission success rate. To evaluate the performance of DCA, we assumed the monitoring network that consists of a cluster-tree in which sensing data is transmitted to the sink. Analysis uses the traffic data which is generated around the sink. As a result, DCA is superior when much traffic is generated. During the experiment assuming the least amount of traffic, IEEE 802.15.4, has the minimum length of active period and 90% data transmission success rate. However DCA maintains 11.8ms of active period length and results in 98.9% data transmission success rate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.585-588
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• 2007

With several enhanced access technologies, users have many changes to select their preference access network. There are great differences between access technologies, users' need to handover from one access network to another is getting bigger. As users' need grows there are several works to archive fast handover between heterogeneous and homogeneous access networks. However traditional handover mechanisms work only on L2 or L3 have several limits that prevent fast and heterogeneous handover. To overcome those limits, IEEE 802.21 WG and IRTF MOBOPTS RG are working for developing handover mechanisms that uses L2 information on theupper layers like L3. This paper introduces two new L2 information and properties can be used to archive fast handover of mobile nodes.