• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3054-3067
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• 2015

The phenomena of higher channel cross polarization discrimination (XPD) is mainly observed for future wireless technologies such as small cell network and massive multiple-input multiple-output (MIMO) system. Therefore, utilization of high XPD is very important and space-polarization division multiple access (SPDMA) with dual-polarized MIMO system could be a suitable solution to high-speed transmission in high XPD environment as well as reduction of array size at base station (BS). By SPDMA with dual-polarized MIMO system, two parallel data signals can be transmitted by both vertically and horizontally polarized antennas to serve different mobile stations (MSs) simultaneously compare to conventional space division multiple access (SDMA) with single-polarized MIMO system. This paper analyzes the performance of SPDMA for maximum ratio transmission (MRT) in time division duplexing (TDD) system by proposed dual-polarized MIMO spatial channel model (SCM) compare to conventional SDMA. Simulation results indicate that how SPDMA utilizes the high XPD as the number of MS increases and SPDMA performs very close to conventional SDMA for same number of antenna elements but half size of the array at BS.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.630-642
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• 2017

In this paper, we propose the opportunistic non-orthogonal multiple access (NOMA)-based cooperative relaying system (CRS) with channel state information (CSI) available at the source, where CSI for the source-to-destination and source-to-relay links is used for opportunistic transmission. Using the CSI, for opportunistic transmission, the source instantaneously chooses between the direct transmission and the cooperative NOMA transmission. We provide an asymptotic expression for the average achievable rate of the opportunistic NOMA-based CRS under Rayleigh fading channels. We verify the asymptotic analysis through Monte Carlo simulations, and compare the average achievable rates of the opportunistic NOMA-based CRS and the conventional one for various channel powers and power allocation coefficients used for NOMA.

• ETRI Journal
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• 제28권1호
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• pp.17-30
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• 2006

In time division duplex (TDD) code division multiple access (CDMA) systems, chip-synchronous transmission in the uplink is obtainable, thus leading to free multiple access interference in flat Rayleigh fading channels plus additive white Gaussian noise. This motivates us to develop a novel cooperative transmission strategy that allows single-antenna devices to benefit from spatial diversity using orthogonal signature sequences. The proposed cooperation is applicable to many digital modulation methods and achieves the fullest diversity level, low implementation complexity, and a full data rate. Closed-form bit-error-rate expressions were also derived and compared to simulation results in order to evaluate its validity. A variety of numerical results demonstrated the cooperation's superiority over single transmission under the same transmit power constraint.

• Journal of information and communication convergence engineering
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• 제22권3호
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• pp.181-188
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• 2024

Herein, an innovative transmission technique that utilizes the satellite aerial terrestrial integrated network (SATIN) architecture in combination with non-orthogonal multiple access (NOMA) communications is proposed. This approach is designed to significantly enhance communication rates, which is critical for modern and future combat capabilities. The effectiveness of the proposed transmission system is validated by conducting a comparative analysis of the sum-throughput results, considering various numbers of transmission nodes within the SATIN structure. The results and analyses reveal that the proposed method outperforms traditional methods such as spatial division multiple access (SDMA) and time division multiple access (TDMA), especially in terms of reducing data loss. This superior performance is primarily due to the advanced capability of NOMA in minimizing interference between signals, resulting in improved sum-throughput outcomes. The implementation of this method is expected to significantly enhance command communications in manned-unmanned combat systems, thereby bolstering overall combat effectiveness through improved transmission rates.

• 한국정보통신학회논문지
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• 제24권5호
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• pp.623-629
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• 2020

본 논문은 협대역 다중전송시스템의 구조 및 다중전송에 적합한 등화기의 성능 분석에 관한 것으로서. 등화 성능의 극대화를 위하여 다중전송에 있어 레인징 기법에 기반한 전송 시점 제어 방법을 제안하고, 제안된 다중 전송기법에 적합한 연판정 및 강판정 조합 궤환 적응 판정 등화기를 제안하였다. 본 논문에서 제안하는 연판정 및 강판정 조합 궤환 적응 등화기는 SNR의 범위에 따라 궤환 적응 등화기의 입력으로 사용되는 판정 방법을 가변하는 것이다. 제안된 기법의 우수성을 입증하기 위하여 페이딩 채널 환경에서 모의실험을 통하여 제안된 방법의 성능을 검증하였다. 성능 검증결과, 기존 방법과 비교하여 본 논문에서 제안하는 방법이 큰 복잡도 증가 없이 기존 방법의 성능을 뛰어넘는 우수한 성능을 보임을 확인하였다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.525-530
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• 2008

There are a few core technologies to enable high-performance $4^{th}$ generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate transmission such as Mobile WiMAX and WLAN. Efficient decrease of inter-carrier interference (ISI) and inter-carrier interference (ICI) are the reasons for why OFDM is suitable for high-performance transmission, 4G mobile communication. In this paper, we mainly focus on two of objects, combination between MIMO and OFDM, and OFDM channel simulator using Ray-tracing algorithm. The results of this paper can be used implementation of a Wireless Software Platform for 4G Mobile Communication Systems.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.783-786
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• 2015

라우팅 정보에 대한 변화를 발생시켜 전송기능을 방해하는 홀 공격은 MANET(Mobile Ad-Hoc Network)과 같은 임시 통신망에 치명적인 결과를 초래한다. 홀 공격의 한 종류인 블랙홀 공격은 악성 노드인 블랙홀 노드가 라우팅 정보를 위조하여 네트워크 내에 전송되는 정보를 흡수함으로서 네트워크 성능을 마비시키는 악성공격의 일종이다. 블랙홀 공격이 MANET의 전송성능에 미치는 영향은 매우 크므로 다양한 네트워크 환경에 대해 블랙홀 공격이 미치는 전송성능을 분석하는 것은 매우 의미있는 일이다. 본 연구에서는 복수의 블랙홀 노드에서 발생된 블랙홀 공격이 MANET의 전송 성능에 미치는 영향을 분석해 본다. 분성 방법으로는 NS-2를 사용한 컴퓨터 시뮬레이션을 활용하며 분석대상 서비스로는 음성 트래픽을 사용한다.

• 한국항공운항학회지
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• 제20권4호
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• pp.39-44
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• 2012

This paper propose a transmission method for "Transportation system" that can decide precise position under wide area road traffic environment. For precise position detecting, central station collect multiple receiver station's satellite navigation data and generate correction information. In this process, we need efficient real time transmission method for satellite navigation message that has variable data size. We propose real time data transmission method. This real time transmission method offer efficient processing structure for multiple receiver station's satellite navigation message. This paper explains proposed real time transmission method and proofs this transmission method.

• 소음진동
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• 제8권5호
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• pp.807-813
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• 1998

Transmission loss of the simple expansion chamber with multiple inlet and outlet ports is obtained. Transfer matrices which represent the relation between the power variables(pressure and velocity) of inlets and outlets depend on the input relatons as well as the acoustic system parameters(i.e. geometry of the chamber, wall admittance, etc.). The analysis has been performed analytically, including the effects of higher order modes for the 2-inlet/1-outlet, 1-inlet/2-outlet and 2-inlet/2-outlet systems. This study yeilds that phase difference between the inlet ports can significantly increase the transmission loss in low frequency range.

• 방송공학회논문지
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• 제24권6호
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• pp.1143-1151
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• 2019

본 논문에서는 단일 반송파 변조방식에서 주파수 대역폭 당 전송효율을 극대화하는 무선전송 방식을 제안한다. 제안된 방식은 파일럿(pilot) 신호 및 전송 프레임 내에서 심벌(symbol)간 보호 구간(guard interval)을 제거하기 위하여 의사 결정 채널 추적(decision directed channel tracking) 기법을 적용하며 롤 오프율(roll-off factor)이 0.05인 레이즈드 코사인(raised cosine) 펄스 정형 기능을 수행한다. 또한, 두 개의 편파 안테나를 사용한 2×2 다중입출력(MIMO) 방식을 적용하며 등화와 신호 분리를 주파수 영역에서 수행한다. 이상의 기술이 적용된 무선 모뎀은 5MHz 주파수 대역폭 하에서 최대 63.3Mbps의 전송속도가 달성됨을 확인한다.