• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4662-4677
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• 2018

The dynamic opportunistic device-to-device (DO-D2D) network will frequently emerge in the fifth generation (5G) wireless communication due to high-density and fast-moving mobile devices. In order to improve the Quality of Experience (QoE) of users with different computing capacity devices in the DO-D2D network, in this paper, we focus on the study of how to reduce the packets retransmission delay and satisfy heterogeneous devices. To select as many devices as possible to transmit simultaneously without interference, the concurrent transmitters-selecting algorithm is firstly put forward. It jointly considers the number of packets successfully received by each device and the device's connectivity. Then, to satisfy different devices' demands while primarily ensuring the base-layer packets successfully received by all the devices, the layer-cooperation instantly decodable network coding is presented, which is used to select transmission packets combination for each transmitter. Simulation results illustrate that there is an appreciable retransmission delay gain especially in the poor channel quality network compared to the traditional base-station (BS) retransmission algorithm. In addition, our proposed algorithms perform well to satisfy the different demands of users with heterogeneous devices.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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• pp.3958-3971
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• 2016

With Internet of Things (IoT) technology, home environment becomes smarter than ever. Not only smart devices such as smart phone or smart TV, but also various IoT devices including sensor, smart thermostat, and smart scale has now become very common on the market. These devices have connectivity to the Internet, so that user can read data from the device or control the device using Internet technology. However, due to diversity of smart home requirements, device collaboration in smart home remains a challenging task still. Usually smart home is built with various technologies to fulfill its own purpose, and these purposes cover very wide area from controlling low-power sensor devices to controlling high-performance devices like smart TV and smart phone. This variety of smart home requirements makes smart home very complicated due to mixed network architecture, protocol and technology. In this paper, a framework to enable managing and collaborating heterogeneous IoT devices in smart home environment is proposed. Several programming models are defined in the proposed framework to make application development for heterogeneous devices more intuitive. The proposed framework has been implemented as a web service, and a case study with real-world smart home IoT devices is presented.

• 디지털산업정보학회논문지
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• 제11권4호
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• pp.25-31
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• 2015

Smart healthcare environments which merge medical and IT technology are getting ready for the third generation centering EHR from current second generation. As a basic technology for the introduction and activation of EHR systems it requires heterogeneous network interworking techniques between various wired and wireless medical devices. Interworking technology for heterogeneous network among various medical devices is needed to introduce EHR system. The heterogeneous network interworking technology is needed for construction of a reliable data system to convert each of unstructured data into structured data. Therefore, in this paper, we identify the domestic and international trends of smart medical field and analyze the characteristics of wired and wireless communication technology that is used in a heterogeneous network. and also suggest requirements needed for interworking technology and provide interworking technology based on them. we expect that proposed method which is designed for smart healthcare environments would provide a basic architecture needed for third smart medical technology generation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1598-1601
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• 2005

In this paper, a heterogeneous home network control system using HNCP is proposed and implemented. A power line and 802.15.4 are used as media for the system. Information about home environment gathered by sensors is transferred to a power line connected device through the 802.15.4. HNCP stimulate the home network based on the both media. Sensor device definition for the HNCP address and message set is proposed. TinyOS supports the HNCP stack on the wireless sensor board. The home network control system implemented with these techniques has a benefit of user friendly operation of home appliances based on the sensing data. Implementation and experiment shows validity of the system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1841-1865
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• 2017

This paper proposes a new interference mitigation scheme for device-to-device (D2D) communications underlaying a cellular network. The object of the proposed scheme is to determine the number of data streams, a precoding matrix, and a decoding matrix of D2D networks so as to maximize the system capacity given the number of data streams of a cellular network while satisfying the constraint of the inter-system interference from D2D networks to the cellular network. Unlike existing interference mitigation schemes based on the interference alignment technique, the proposed scheme operates properly regardless of the number of data streams of a cellular network and moreover it does not require changing the precoding and decoding matrices of a cellular network. The simulation results demonstrate that the proposed scheme significantly increases the system capacity by mitigating the intra- and inter-system interference.

• 한국통신학회논문지
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• 제31권7B호
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• pp.583-594
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• 2006

WPAN은 데이터 속도 영역, 가입자 규모, 지원되는 이동성 레벨 등의 여러 가지 요구 사항에 따라 다양한 형태로 발전되어 왔다. 또한 여러 종류의 네트워크 인터페이스를 가진 휴대 장치가 일반화되고 있다. 이러한 다중 모드 장치가 여러 종류의 WPAN 장치들과 어느 곳 어느 때든지 통신하기 위해서는 이종 무선 네트워크를 위한 프레임워크가 필요하다. 이에 본 논문에서는 이종 WPAN을 통합 할 수 있는 통합 프레임워크를 제안한다. 그리고 프레임워크의 요구사항 및 상세 설계에 대해 설명하고, 에뮬레이션 테스트 결과를 제시하였다.

• 인터넷정보학회논문지
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• 제9권6호
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• pp.63-72
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• 2008

최근의 이기종 네트워크 관리에 대한 연구는 단순히 PKI를 이용한 방식으로 이루어지고 있는 실정이며, 실제 이기종 네트워크가 구현되었을때 나타날 수 있는 다양한 형태의 보안 연구가 미흡하다. 따라서 다양한 보안 요구사항과 이를 만족하는 보안 관리 프로토콜 개발은 안전한 이기종 네트워크 환경에 매우 절실히 요구되는 사항이다. 본 논문에서는 기존의 연구에서 고려사항으로 제시되었던 보안적 사항을 만족하는 이기종 네트워크의 안전하고 효율적인 관리 방식을 제시한다. 제시된 방식은 사용자의 프라이버시 보호를 위해 정적인 중앙 개체와 중간 개체를 이용해 상호 인증과정을 수행하고 사용자들간의 통신이 필요한 경우 1-out-2 분실 통신로를 이용해 암호 통신을 수행함으로써 안전성 뿐만 아니라 통신의 효율성까지 고려한 방식이다. 특히, TTP를 기반으로 이기종 네트워크에서 요구되는 다양한 서비스와 관련된 보안과 효율성을 높이기 위한 방식으로 기존 논문에서 전자 상거래에 사용하던 모바일 단말기를 이용해 다양한 서비스를 제공하고 임시 그룹을 설정하여 동적인 환경에 적합한 관리 방식을 제안하였다.

• 한국통신학회논문지
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• 제37권3C호
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• pp.233-240
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• 2012

일반적인 네트워크를 통한 공장 내 관리와 달리 무선 센서 네트워크를 이용한 공장 내 관리를 위해서는 장치의 발견, 확인, 검증의 과정이 자동으로 수행되어야 한다. 이에 대한 방안으로 본 논문에서는 장치 등록 서버를 제안하고 이를 이용한 관리 시스템을 설계한다. 장치의 발견단계에서는 무선 센서 망에서 사용되는 라우팅 기술의 특성을 이용하고 식별 및 검증 단계에서는 장치를 식별할 수 있는 일반적인 정보를 장치 등록 서버에 저장하여 활용한다. 제안하는 관리 시스템은 구현의 복잡성을 낮추고 여러 종류의 장치들이 분산되어 있는 공장 내에서의 장치 관리를 용이하게 해준다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 추계학술발표대회
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• pp.48-51
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• 2011

Universal Plug and Play (UPnP) is one of the most promising home network middleware technologies because of its straightforward implementation and zero configuration characteristics. However, it has a limitation of the operations only IP based network and proceeding in a single IP subnet. In this paper, we proposed network bridge architecture for UPnP network to interoperate heterogeneous network, UPnP and ZigBee. The proposed network bridge architecture is capable of configuration ZigBee device as a virtual UPnP device. This technique is promising for seamless inter-networking with ZigBee and UPnP network. Also, the architecture of the proposed network bridge architecture can be applied for a future smart home.

• Journal of Information Processing Systems
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• 제18권6호
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• pp.803-812
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• 2022

With the increasing number of mobile device users worldwide, utilizing mobile edge computing (MEC) devices close to users for content caching can reduce transmission latency than receiving content from a server or cloud. However, because MEC has limited storage capacity, it is necessary to determine the content types and sizes to be cached. In this study, we investigate a caching strategy that increases the hit ratio from small base stations (SBSs) for mobile users in a heterogeneous network consisting of one macro base station (MBS) and multiple SBSs. If there are several SBSs that users can access, the hit ratio can be improved by reducing duplicate content and increasing the diversity of content in SBSs. We propose a Deep Q-Network (DQN)-based caching strategy that considers time-varying content popularity and content redundancy in multiple SBSs. Content is stored in the SBS in a divided form using maximum distance separable (MDS) codes to enhance the diversity of the content. Experiments in various environments show that the proposed caching strategy outperforms the other methods in terms of hit ratio.