• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.1984-2002
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• 2020

With the appearance of wireless spectrum crisis in traditional cellular network, device-to-device (D2D) communication has been regarded as a promising solution to ease heavy traffic burden by enabling precise content delivery among mobile users. However, due to the channel sharing, the interference between D2D and cellular users can affect the transmission rate and narrow the throughput in the network. In this paper, we firstly present a weighted interference minimization cluster formation model involving both social attribute and physical closeness. The weighted-interference, which is evaluated under the susceptible-infected(SI) model, is utilized to gather user in social and physical proximity. Then, we address the cluster formation problem via spectrum clustering with iterative operation. Finally, we propose the stable matching theory algorithm in order to maximize rate oriented to accomplish the one-to-one resource allocation. Numerical results show that our proposed scheme acquires quite well clustering effect and increases the accumulative transmission rate compared with the other two advanced schemes.

• 인터넷정보학회지
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• 제6권4호
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• pp.19-25
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• 2005

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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• pp.3641-3655
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• 2016

Wireless sensor networks (WSNs) provide a promising approach to monitor the physical environments, to prolong the network lifetime by exploiting the mutual correlation among sensor readings has become a research focus. In this paper, we design a hierarchical network framework which guarantees layered-compression. Meanwhile, a data sorting-based adaptive spatial compression scheme (DS-ASCS) is proposed to explore the spatial correlation among signals. The proposed scheme reduces the amount of data transmissions and alleviates the network congestion. It also obtains high compression performance by sorting original sensor readings and selectively discarding the small coefficients in transformed matrix. Moreover, the compression ratio of this scheme varies according to the correlation among signals and the value of adaptive threshold, so the proposed scheme is adaptive to various deploying environments. Finally, the simulation results show that the energy of sorted data is more concentrated than the unsorted data, and the proposed scheme achieves higher reconstruction precision and compression ratio as compared with other spatial compression schemes.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.981-985
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• 2006

와이브로(Wibro)는 Wireless Broadband Internet의 줄임말로, 휴대 인터넷, 무선 광대역 인터넷, 무선초고속 인터넷으로 풀이됨. 언제(anytime), 어디서나(anywhere), 누구나(anyone), 어떤 장비(my device)로 이동하면서도 초고속으로 인터넷을 이용할 수 있는 서비스로, 이동전화와 무선 LAN의 중간영역에 위치하며, 와이브로 서비스는 기존 셀률러망과 다르게 IP망을 기반으로 서비스되기 때문에 단말기의 이동과 관계없이 끊임없이 연결을 유지하기 위해서는 핸드오버가 지원되어야 한다. 기존의 Micro Mobility 방식과 일반적인 Mobile IP 방식은 핸드오프시 지연속도와 패킷손실의 문제점을 가지고 있다. 이러한 문제점을 최소화 하기위해서 IETF라는 프로토콜이 제안되고, IETF의 Mip4, Mip6, Mipshop WG을 중심으로 표준화가 진행되고 있다. 본 논문에서는 와이브로 망에서의 문제점을 개선하여 단말기의 효율적인 핸드오버 지연을 최대한 줄이기 위한 기법과 활성화 및 전망에 대해 연구 분석 함.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1832-1853
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• 2018

The personal health record (PHR) system is a promising application that provides precise information and customized services for health care. To flexibly protect sensitive data, attribute-based encryption has been widely applied for PHR access control. However, escrow, exposure and abuse of private keys still hinder its practical application in the PHR system. In this paper, we propose a coordinated ciphertext policy attribute-based access control with user accountability (CCP-ABAC-UA) for the PHR system. Its coordinated mechanism not only effectively prevents the escrow and exposure of private keys but also accurately detects whether key abuse is taking place and identifies the traitor. We claim that CCP-ABAC-UA is a user-side lightweight scheme. Especially for PHR receivers, no bilinear pairing computation is needed to access health records, so the practical mobile PHR system can be realized. By introducing a novel provably secure construction, we prove that it is secure against selectively chosen plaintext attacks. The analysis indicates that CCP-ABAC-UA achieves better performance in terms of security and user-side computational efficiency for a PHR system.

• 한국전자통신학회논문지
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• 제5권5호
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• pp.528-533
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• 2010

인터넷 전화의 사용이 증가하고 있고 최근에는 스마트폰이 보급됨에 따라서 스마트폰을 통한 인터넷 전화 서비스 이용이 급격하게 증가할 것으로 예상되고 있다. 특히 국내의 경우 이미 전국 상당 지역에 설치된 와이브로를 통한 인터넷 전화 서비스의 제공은 와이브로의 활성화로 이어질 수 있는 좋은 기회라 할 수 있다. 그런데 기존의 전화망이나 이동전화망을 통한 전화 서비스와는 달리 인터넷 전화는 서비스 품질이 보장될 수 없다는 문제점이 있고 특히 무선 환경을 통한 모바일 인터넷 전화 서비스의 경우 이 문제점은 더 심각해 질 수 있다. 따라서 보다 더 엄격하고 체계화된 모바일 인터넷 전화 서비스 품질 관리 방안이 마련될 필요성이 있다. 이를 향한 첫 단계로서 본 논문은 와이브로를 통한 모바일 인터넷 전화 서비스의 품질을 관리하기 위한 방안을 제안하고 이를 구현하기 위하여 개발된 소프트웨어의 개발 과정을 설명한다. 개발된 소프트웨어는 사용자 단말에 장착되어 전체적인 모바일 인터넷 전화 서비스의 품질을 VoIP 품질지표, 네트워크 품질지표, 무선 품질지표로 분류하여 측정함으로써 보다 효율적인 품질 관리가 가능하다는 장점이 있다.

• International journal of advanced smart convergence
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• 제4권2호
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• pp.14-19
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• 2015

Recently, water sewage disposal facilities are able to manage real-time data collection and record management through compact broadband modem LAN switching technology. Therefore, it needs more stable and efficient facility management. So, we required practical use of environmental facilities convergence based on broadband integrated modem. In this paper, we proposed short distance wireless communication network of compact broadband modem for sewage disposal facilities. And it received data inside of water treatment facility using the two communication methods (IEEE802.11x and IEEE802.15.4x). Then, our proposed an data-flow control algorithm of wireless network technology will prioritize processing data when emergency happen through collecting data, analysis data and processing. Lastly, we proved usefulness by experiment and simulation analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2375-2393
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• 2016

Key agreement is paramount in secure wireless communications. A promising approach to address key agreement schemes is to extract secure keys from channel characteristics. However, because channels lack randomness, it is difficult for wireless networks with stationary communicating terminals to generate robust keys. In this paper, we propose a Robust Secure Key Agreement (RSKA) scheme from Received Signal Strength (RSS) in stationary wireless networks. In order to mitigate the asymmetry in RSS measurements for communicating parties, the sender and receiver normalize RSS measurements and quantize them into q-bit sequences. They then reshape bit sequences into new l-bit sequences. These bit sequences work as key sources. Rather than extracting the key from the key sources directly, the sender randomly generates a bit sequence as a key and hides it in a promise. This is created from a polynomial constructed on the sender's key source and key. The receiver recovers the key by reconstructing a polynomial from its key source and the promise. Our analysis shows that the shared key generated by our proposed RSKA scheme has features of high randomness and a high bit rate compared to traditional RSS-based key agreement schemes.

• 한국전자파학회논문지
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• 제16권10호
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• pp.1003-1009
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• 2005

본 논문에서는 결함접지구조(Defected Ground Structure: DGS)의 전파 지연 특성을 이용하여 소형으로 구현한 휴대 인터넷용 고전력 Single Pole Double Throw(SPDT) 스위치의 특성이 제공되며 1/4 파장 전송선을 이용하여 제작된 일반적인 방식의 스위치와 그 특성이 비교된다. DGS를 활용하여 제작된 스위치는 높은 격리도를 확보하기 위해 병렬구조의 다이오드를 사용하여 구성되었으며 2.3 GHz에서 0.8 dB의 삽입 손실과 50 dB 이상의 격리도 특성을 보였고 50 W 이상의 전력을 다룰 수 있었다. DGS를 활용한 스위치는 기존의 전송선 방식의 스위치와 거의 동일한 스위칭 특성을 보이면서도 $50\%$ 가까운 회로의 크기 감소를 달성할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권5호
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• pp.2063-2081
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• 2018

A resource allocation algorithm is proposed in this paper to simultaneously minimize the total system power consumption and maximize the system throughput for the downlink of multi-user multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. With the Lagrange dual decomposition method, we transform the original problem to its convex dual problem and prove that the duality gap between the two problems is zero, which means the optimal solution of the original problem can be obtained by solving its dual problem. Then, we use convex optimization method to solve the dual problem and utilize bisection method to obtain the optimal dual variable. The numerical results show that the proposed algorithm is superior to traditional single-objective optimization method in both the system throughput and the system energy consumption.