• Journal of Multimedia Information System
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• 제3권4호
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• pp.135-140
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• 2016

To improve the throughput of Device-to-Device (D2D) communication, we focus on the scenario where D2D pair can reuse multi-channel of cellular communication. However, as sharing same channel with cellular communication can cause interference between D2D communication and cellular communication, a proper interference management is needed. In this paper, we propose interference-based channel allocation to select the channels to be used by D2D communication and a solution from game theory perspective to optimize the D2D communication throughput under multi-channel as well as guarantee the interference from it to cellular network. The simulation results verify the stability of the proposed method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.39-40
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• 2006

This paper modeled UWB system transmission channel in indoor environment. For channel modeling, we extracted transmission channel parameter, and then measured from 10MHz to 16.01GHz by using method of CIR(Channel Impulse Response) and CTF(Channel Transfer Function) in small room($5.5{\times}5.5m^2$) environment.

• Journal of Information Processing Systems
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• 제11권3호
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• pp.342-353
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• 2015

It is widely accepted that single carrier frequency division multiple access (SC-FDMA) is an excellent candidate for broadband wireless systems. Channel estimation is one of the key challenges in SC-FDMA, since accurate channel estimation can significantly improve equalization at the receiver and, consequently, enhance the communication performances. In this paper, we study the application of compressive sensing for sparse channel estimation in a SC-FDMA system. By skillfully designing pilots, their patterns, and taking advantages of the sparsity of the channel impulse response, the proposed system realizes channel estimation at a low cost. Simulation results show that it can achieve significantly improved performance in a frequency selective fading sparse channel with fewer pilots.

• 한국인터넷방송통신학회논문지
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• 제19권4호
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• pp.7-12
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• 2019

주변 후방산란 통신은 송신 전력효율 문제로 기존 RF통신에서 채널 추정방법인 파일럿(pilot) 신호를 통한 채널 추정기법이 제한된다. 제한된 송신 전력 환경에서 기존 주변 후방산란통신의 연구는 채널 상태로 인한 신호 변동을 고려하지 않은 이상적인 채널로 가정을 하고 연구되어 왔다. 본 논문은 주변 후방산란 통신 시스템에서 정규분포를 따르는 채널 상태인 주변 후방산란 통신 시스템에서 채널 추정 방법으로 블라인드 채널 추정기법 중 하나인 기댓값-최대화 알고리즘을 제안한다. 모의실험은 제안한 시스템 모델에서 기댓값-최대화 알고리즘과 추정값의 최소 분산을 나타내는 Bayesian Cramer-Rao 하한 경계를 이용하여 평균 제곱 오차(Mean Square Error, MSE)값이 하한 경계와 근접해 가는 것을 확인하고, 주변 후방산란 통신 시스템에서 채널 파라미터의 추정이 가능함을 증명한다.

• ETRI Journal
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• 제37권3호
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• pp.439-449
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• 2015

Human body communication (HBC) is being recognized as a new communication technology for mobile and wearable devices in a body area network (BAN). This paper presents co-channel interference experienced by HBC supporting the physical layer in the IEEE 802.15.6 BAN standard. To analyze the co-channel interference, a co-channel interference model is introduced, and space-domain and time-domain parameters representing an interference environment are generated using the co-channel interference model. A new signal-to-interference ratio (SIR) parameter depending on the peak amplitudes of the data signals causing co-channel interference is defined; co-channel interference can be easily analyzed and modelled using the newly defined SIR. The BER degradation model derived using the co-channel interference model and SIR in this paper can be effectively used to estimate the performance.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.1000-1005
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• 2008

본 미 정부는 열악한 채널환경에 강인한 통신 성능을 제공하기 위해 MELP 알고리즘을 새로운 군사 표준 보코더 알고리즘을 제시하였다. 논문에서는 HF channel 환경에서 MELP부호화 방식을 이용한 보안 통신의 전송영향을 분석하였다. MELP부호화 방식은 HF채널에 적합하게 적용되도록 개발되었으며 무선 버스터 환경에서 MELP 부호화 영향과 채널부호화 방식을 적용함으로써 평문통신과 보안통신의 성능을 MOS와 스펙트럼 분석을 통해 성능을 고찰하였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.65-66
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• 2005

This paper presents an adaptive satellite communication systems to adapt channel environment. High performance coding and modulation techniques are applied to poor channel condition, otherwise, bandwidth efficient coding and modulation techniques are applied to good channel condition to obtain high transmission rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.911-923
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• 2014

Ad hoc cognitive radio wireless sensor networks allow secondary wireless sensor nodes to recognize spectrum opportunities and transmit data. Most existing protocols proposed for ad hoc cognitive radio wireless sensor networks require a dedicated common control channel. Allocating one channel just for control packet exchange is a waste of resources for channel-constrained networks. There are very few protocols that do not rely on a common control channel and that exchange channel-negotiation control packets during a pre-allocated time on the data channels. This, however, can require a substantial amount of time to access the channel when an incumbent is present on the channel, where the nodes are intended to negotiate for the data channel. This study examined channel access delay on cognitive radio wireless sensor networks that have no dedicated common control channel.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.40-44
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• 2010

opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. A dynamical sensing range as a important parameter introduced to maintain the our protocol performance. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.17-22
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• 2022

Due to the recent advances in high-speed communication technologies as well as the easy production of high-quality video contents, IPTV is becoming increasingly popular. Meanwhile, as the number of IPTV channels increases, channel search time to find the desired channel keeps increasing. In this paper, we discuss how to improve the channel search latency in IPTV, and introduce caching and prefetching techniques that are widely used in memory management systems. Specifically, we adopt memory replacement, prefetching, and caching techniques in IPTV channel search interfaces and show the effectiveness of these techniques as the number of channels are varied.