• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1042-1047
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• 1999

In this paper, two kinds of digital predistorters are proposed and their performances are analyzed in order to minimize ACI and SNR degradation caused by nonlinearly amplified TC-16QAM signal and to transmit high speed data in power and bandwidth limited land mobile satellite channel. Our simulation results show that LUT predistorter reduces the out-of-band ACI more efficiently as compared to intersymbol interpolated predistorter. Regarding the reduction of in-band SNR and total power intersymbol interpolated predistorter outperforms LUT predistorter. In the simulation mobile satellite channel and nonlinear HPA are modeled by Rician channel and Fujitsu SSPA, respectively.

• Journal of the Institute of Convergence Signal Processing
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• v.18 no.2
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• pp.37-42
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• 2017

In this paper, we study on symbol error rate(SER) performance of frequency domain decision feedback equalization for modelled underwater channel. Underwater channel is generated by Bellhop model. Simulation results show that proposed method is efficient for underwater acoustic communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.9
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• pp.557-559
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• 2014

We propose an efficient resource allocation scheme based on interference awareness for D2D (Device-to-Device) communication in cellular networks. Recently, many researchers have studied how to allocate frequency resources to DUE (D2D User Equipment) with full interference channel information. However, it is difficult to assume a scenario where instantaneous interference information between the CUE (Cellular UE) and DUE is known to the BS (Base Station). To tackle this problem, we proposed in this paper a new scheme in which the BS allocates a resource to CUE and DUE without a full channel information and can aware interference based on only transmit power and distance between UEs. Simulation results show effectiveness of the proposed scheme.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.481-486
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• 2022

The recent rapid growth of the IoT(Internet of Things) is leading to the spread of low-power wireless technology. A major challenge in designing IoT wireless networks is to achieve coexistence between different wireless technologies that share the 2.4 [GHz] ISM (Industrial Scientific Medical) frequency band. Therefore, there is a need for research on improving the reliability of wireless networks and coexisting operation between wireless networks. In particular, it is necessary to study an interference model and performance for mutual service coexistence in a BLE (Bluetooth Low Energy) wireless network environment, which is expected to be widely used as a connection medium between devices in various industrial fields. In this paper, the co-channel interference model with the IEEE 802.15.4 system is established focusing on the physical layer of the BLE system widely used in residential and industrial wireless applications, and the performance of the BLE wireless communication system is analyzed in the co-channel interference environment. As a result of the analysis, as the distance between the interference source and the BLE system increases in an environment where noise and co-channel interference exist, the amount of co-channel interference decreases and the error rate performance of the BLE system improves.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.78-83
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• 2015

In this paper, when WLAN repeater of satellite communication package system as a novel wireless disaster communication network connected to LTE D2D mobile terminal, we analyzed radio channel interference from WLAN and WPAN system of adjacent same ISM band using Monte-Carlo method. In this study, WLAN cell radius was determined using Extended Hata Model considering practical environment, and simulated physical protection distance and density in the dense-mode to minimize interference from WLAN, Bluetooth, and ZigBee. Simulation results, WLAN repeater can be operated with 15 WLAN interferer over 130m distance, 23 Bluetooth interferer over 100m distance, and with 62 ZigBee interferer over 83m distance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.701-704
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• 2005

In this paper, we looked into the feature of a transmission system of the terrestrial digital broadcasting system and considered a ATSC 8-VSB transmission standard. Also, we analyzed the performance with the influence of an interchannel interference by the ATSC standard. As a result, the case not to consider Rician fading, The influence of the interfere did not exist if Frequency interval fell off over the 20MHz. The case to consider Rician fading, the system had the degradation of the performance.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.117-124
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• 2011

In this paper, we present more effective throughput enhancement technique to improve the data rate and reliability by using the multiple antenna technique. The conventional spatial diversity scheme is limited in according with the interference from each antenna channel status, and the orthogonality of spreading codes and subcarriers are destroyed due to the frequency selectivity. Proposed system is considered MC-CDMA system with 4 transmit antennas and 1 receive antenna. Proposed system based on SVD with the MS-RLS MMSE subcarrier combining method in order to achieve better performance with low computational complexity. Via computer simulation, we confirm that the proposed system is able to improve the BER performance by suppressing the interference of other antenna signals.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.223-227
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• 2002

Eureka 747 DAB 시스템의 혼신보호비는 AM, FM, PAL, SECAM, DAB 등의 동일채널 및 인접채널 간섭원에 대한 조사가 수행되었으나, NTSC TV 간섭원에 대해서는 분석되지 않았다. Eureka 141 DAB 시스템 대부분이 TV 대역인 Band III에서 운용되는 상황을 고려한다면, NTSC TV 간섭원에 대한 혼신보호비 분석은 반드시 필요하다. 본 논문에서는 Eureka 147 DAB 시스템과 아날로그 NTSC TV 시스템간의 혼신보호비중 NTSC TV 간섭원에 대한 Eureka 147 DAB 시스템의 혼신보호비 측정을 위한 간섭환경 설정방법 및 DAB송수신기를 이용한 BER 측정방법, 그리고 측정결과를 제시한다.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.217-223
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• 2010

In this paper, an interchannel interference (ICI) cancellation method is proposed for multiple frequency offsets in orthogonal frequency division multiplexing (OFDM) systems. When several same signals are received from different transmitters simultaneously, multiple frequency offsets may occur at the receiver because of the frequency difference of the oscillators of the two transmitters and the receiver. This causes degradation of system performance because OFDM systems are very sensitive to the frequency offsets. In this paper, we propose a method to eliminate the effect of the multiple frequency offsets for OFDM systems. The method is accomplished in two steps: compensation of the frequency offset in the time domain and subsequent cancellation of the ICI in the frequency domain. Through computer simulations, we verify the effectiveness of the proposed ICI cancellation method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.693-701
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• 2008

In OFDMA (Orthogonal Frequency Division Multiple Access) system that frequency reuse factor is 1, as the same channels in the neighborhood cells creates inter-cell co-channel interference which provides a resource underutilization problem, channel allocation schemes to minimize inter-cell interference have been studied. This paper proposes a new CNIR (Carrier to Noise and Interference Ratio)-based distributed Inter-cell DCA (Dynamic Channel Allocation) algorithm in the OFDMA environment with frequency reuse factor of 1. When a channel allocation is requested, if there is not a free channel in home cell or the available free channels in home cell do not satisfy a required threshold value, the proposed Inter-cell DCA algorithm finds CNIR values of available free channels in the neighborhood cells and then allocates a free channel with maximum CNIR value. Through the simulation results, we find that the proposed scheme decreases both new call block rate and forced termination rate due to new call generation at the same time because it increases channel allocation probability.