• Journal of Communications and Networks
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• v.16 no.4
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• pp.465-474
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• 2014

Wireless sensor network (WSN) is considered to be one of the most important research fields for ubiquitous healthcare (u-healthcare) applications. Healthcare systems combined with WSNs have only been introduced by several pioneering researchers. However, most researchers collect physiological data from medical nodes located at static locations and transmit them within a limited communication range between a base station and the medical nodes. In these healthcare systems, the network link can be easily broken owing to the movement of the object nodes. To overcome this issue, in this study, the fast link exchange minimum cost forwarding (FLE-MCF) routing protocol is proposed. This protocol allows real-time multi-hop communication in a healthcare system based on WSN. The protocol is designed for a multi-hop sensor network to rapidly restore the network link when it is broken. The performance of the proposed FLE-MCF protocol is compared with that of a modified minimum cost forwarding (MMCF) protocol. The FLE-MCF protocol shows a good packet delivery rate from/to a fast moving object in a WSN. The designed wearable platform utilizes an adaptive linear prediction filter to reduce the motion artifacts in the original electrocardiogram (ECG) signal. Two filter algorithms used for baseline drift removal are evaluated to check whether real-time execution is possible on our wearable platform. The experiment results shows that the ECG signal filtered by adaptive linear prediction filter recovers from the distorted ECG signal efficiently.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.137-146
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• 2006

IP address lookup has become a major bottleneck of packet forwarding and a critical issue for high-speed networking techniques in routers. In this paper, we propose an efficient high-speed IP address lookup scheme using adaptive multiple hashing and prefix grouping. According to our analysis results based on routing data distributions, we grouped prefix lengths and selected the number of hash functions in each group adaptively. As a result, we can reduce collisions caused by hashing. Accordingly, a forwarding table of our scheme has good memory efficiency, and thus is organized with the proper number of memory modules. Also, the proposed scheme has the fast building and searching mechanisms to develop the forwarding table only during a single memory access.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1607-1617
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• 2010

In this paper we propose MA-CBRP, mesh adaptive algorithm for wireless mesh networks. MA-CBRP is a hybrid algorithm based on ad-hoc CBRP protocol. In MA-CBRP, the mesh router periodically sends the ANN message as like Hello-message in CBRP. ANN message allows to all clients periodically store a route towards the mesh-router and renewal information in their routing cache. While CBRP periodically reply Hello-message, MA-CBRP does not reply to achieve less overhead. After receiving ANN message, mesh client send JOIN message to mesh router when the route towards mesh router changed. at the same time Register the entry to mesh router, it can achieve to reduce overhead of control the route and shorten the time to find route. consequently, MA-CBRP shows 7% reduced overhead and shortened time to find route than CBRP with regardless of clients number.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.994-1005
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• 2011

In this paper, we propose a novel approach to optimize the movement of mobile sink node, called AMSP(Adaptive Mobile Sink Path) for mobile sensor network environments. Currently available studies usually suffer from unnecessary data transmission resulting from random way point approach. To address the problem, we propose a method which uses the Hilbert curve to create a path. The proposed method guarantees shorten transmission distance between the sink node and each sensor node by assigning orders of the curve according to sensor node density. Furthermore, The schedule of the sink node is informed to all of the sensing nodes so that the Duty Cycle helps the network be more energy efficient. In our experiments, the proposed method outperforms the existing works such as TTDD and CBPER by up to 80% in energy consumption.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.673-684
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• 2004

As the wireless mobile communication is being widespread, mobile technologies will have important roles in the communication with the explosive growth of demanding for wireless portable devices. Among the mobile technologies, a great deal of interest has been taken in mobile ad hoc network (MANET), which is a collection of wireless mobile nodes forming a temporary network without the aid of stationary infrastructure in recent. Furthermore, considering characteristic of ad hoc networks, the design of efficient routing protocols is an important issue. In recent years, on-demand protocols among routing protocols have noticed because of the low routing overhead. However, on-demand protocols suffer from production of the enormous query Packets by broadcasting in order to setup routes, that is, a flooding scheme. The flooding scheme is very costly and results in serious problem, which we refer as the broadcast storm problem. In this paper, we propose a Dynamic Adaptation Query flooding Using Neighbor Topology (NT-DAQ) scheme, in order to resolve the broadcast storm Problem. When a route discovery is in progress, each mobile node decides on the basis of neighbor topology information whether discovery process participates or not. Therefore, our proposed scheme enables to improve network performance in which minimize the number of query rackets. We evaluate the efficiency of our proposed scheme through simulation.

• The KIPS Transactions:PartC
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• v.18C no.3
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• pp.167-178
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• 2011

As the growth of ubiquitous services, various types of ad hoc networks have emerged. In particular, wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are widely known ad hoc networks, but there are also other kinds of wireless ad hoc networks in which the characteristics of the aforementioned two network types are mixed together. This paper proposes a variant of the Low Energy Adaptive Cluster Hierarchy (LEACH) routing protocol modified to be suitable in such a combined network environment. That is, the proposed routing protocol provides node detection and route discovery/maintenance in a network with a large number of mobile sensor nodes, while preserving node mobility, network connectivity, and energy efficiency. The proposed routing protocol is implemented with a multi-hop multi-path algorithm, a topology reconfiguration technique using node movement estimation and vibration sensors, and an efficient path selection and data transmission technique for a great many moving nodes. In the experiments, the performance of the proposed protocol is demonstrated by comparing it to the conventional LEACH protocol.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.94-96
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• 2006

센서네트워크에서 라이프타임에 관한 기존 연구는 다음 노드까지 데이터를 전송하는데 필요한 에너지 혹은 데이터의 생성 속도 등 미리 정해진 몇몇 값에 의존하는 경향이 있어 동적인 네트워크의 상황을 제대로 반영하지 못한다. 본 논문에서 제시하는 라우팅 알고리즘은 주기적으로 배터리의 전압값을 읽고 시간당 전압 감소율을 계산하여 각 노드의 작동 가능한 시간을 계산한다. 또 하드웨어에 따른 배터리 소비 특성을 데이터베이스화하여 참고하기 때문에 보다 정확한 라이프타임의 예측이 가능하다. 이렇게 계산된 결과를 바탕으로 라이프타임이 큰 노드만 선택하여 데이터를 전송하기 때문에 전체 네트워크가 동작하는 시간을 연장시킬 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.691-693
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• 2004

Mobile Ad hoc network은 stationary infrastructure의 도움 없이 이동 노드들이 필요 시 multi-hop wireless links network 형태를 구성하여 통신이 이루어지게 하는 network이다. 따라서 효율적인 라우팅 프로토콜의 개발이 중요한 issue인데 최근에는 routing overhead가 적은 on-demand 프로토콜이 주목을 받고 있다. On-demand 프로토콜은 새로운 route을 구성하기 위해서 query packet을 broadcasting하게 되는데, 특히 노드들의 mobility가 많은 mobile ad hoc network(MANET)의 경우에는 더욱더 자주 발생하게 되는데, blind broadcasting은 neighbor 노드들 간의 radio transmission region overlap에 의해 redundancy, contention, collision 같은 broadcast storm 문제를 발생시키게 된다. 본 논문은 on-demand 프로토콜의 broadcast storm 문제를 해결하기 위해 Neighbor Topology을 고려 한 Dynamic Adaptation Query flooding scheme을 제시한다. 또한 Dynamic Adaptive Query flooding scheme은 broadcast storm 문제 해결뿐만 아니라 network의 congestion을 감소시켜 data packet의 성능 향상에도 기여 할 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.746-748
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• 2011

MANET(Mobile Ad-hoc Network) is a self-configuration network or wireless multi-hop network based on inference topology. The proposed ATICC(Adaptive Time Interval Clustering Control) algorithm for hierarchical cluster based MANET. The proposed ATICC algorithm is time interval control technique for node management considering the attribute of node and network traffic. ATICC could be made low the network traffic. Also it could be improving the network life time by using timing control method.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.647-650
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• 2006

무선 센서 네트워크에서는 다른 네트워크보다 전력 공급이 큰 제약으로 작용하고 있는데, 본 논문에서는 클러스터를 기반으로 하는 프로토콜에서 클러스터를 구성하는 센서 노드의 밀도에 따라서 클러스터 헤더에게 데이터를 전송하는 노드 수를 조정하는 방법을 제안한다. 제안하는 스케줄링 개념은 노드 밀도가 큰 클러스터에서는 클러스터 멤버 노드들의 라운드 당 데이터 전송 회 수를 줄임으로써 전송 에너지 소모를 줄일 수 있으며 네트워크 전체의 라이프 타임을 증가 시킬 수 있다.