• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.865-872
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• 1998

This paper proposes a multiuse detection system in a multi-cell M-ary Frequency Shift Keying(MFSK)/frequency hopping(FH)-Code Division Multiple Access(CDMA) environment, in which the channel model is an OR-channel and in the reverse link. We have proposed a multiuse detection system in a single cell. However, this sitye is not adequate to detect multiuser in a multi-cell environment. Therefore, we propose a multiuser detection system based on 3 level OR decision with two threholds. The proposed detection system can delete interference as well as intra-cell interference, receive the weakened desired signal and reject the false alarm. computer simulation shows the performance improvement.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.15-19
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• 2003

In this paper, the bit error rate (BER) performance of the fast frequency hopping/M-ary frequency shift keying system using the clipper receiver is analyzed by using the characteristic function (CF) technique in the presence of n=1 band multitone jamming and additive white Gaussian noise environment. The CFs of the clipper receiver outputs are derived as a infinite series representation using Gamma function and Marcum's Q -function. The analytical results are validated with various simulation results. Performance comparisons with linear combining receiver are shown that the BER performance of the clipper receiver is much better than that of the linear combining receiver In addition, as the clipping level approaches to infinity, it is shown that the clipper receiver simply performs a linear combining without clipping and there exists an optimum value of diversity level (the number of hops per symbol) that maximizes the worst case BER performance of the clipper receiver.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.684-687
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• 2001

본 논문에서는 이동통신 시스템에서 성능 열화의 주요 원인인 주파수 선택성 페이딩과 전자기기에서 발생하는 임펄간 간섭 환경에서 DS/CDMA 시스템의 성능 개선을 정량적으로 분석하였다 시스템으로 고려한 변식은 비동기식 MFSK와 MDPSK를 이용한 MFSK-MBPSK 결합변조 방식이다. 분석 결과, 선택성 페이딩에서 합성변조 시스템에 대하여 E$_{b}$/Nn$_{o}$ =20일 때를 기준으로 한 경우, M$_{f}$ =4, M$_{p}$=2인 경우가 가장 성능이 좋았으며, 그 다음으로 M$_{f}$ =2, M$_{p}$=4인 경우, 그리고 M$_{f}$ =4, M$_{p}$=4인 순서대로 오율 성능이 좋았다. 그리고 MRC 다이버시티 기법 및 부호화 기법을 채용한 경우 효과적으로 시스템 성능의 열화를 보상할 수 있었다. 또한, 합성변조기법을 사용함으로써 강한 임펄스 환경에서도 만족할 만한 시스템 성능을 얻을 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1161-1168
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• 2010

The FHSS(Frequency Hopping Spread Spectrum), in which a transmitter changes its carrier frequency according to a certain hopping pattern, is widely used in the military communication system, since it is highly resistant to deliberate Jamming. However, the difference of BER performance of satellite communication system which using the different modulation scheme and Jamming model was not studied. Thus, in this paper, we consider PBNJ(Partial-Band Noise Jamming) and WPBJ(Worst case Partial-Band noise Jamming) as Jamming models, and evaluate BER(Bit Error Rate) performances of NC-MFSK(Non-Coherent M-ary Frequency-Shift Keying), SDPSK(Symmetric Differential Phase-Shift Keying), and GMSK(Gaussian filtered Minimum-Shift Keying) modulation schemes. Based on the results, we suggest the best transmission method for each condition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.4
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• pp.342-353
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• 1997

This paper presents an analytical evaluation of a hybrid direct-sequence/slow frequencyhopped code division multiple-access (DS/SFH-CDMA) system employing noncoherent M-ary frequency shift keying(MFSK) modulation in a multiple Nakagami fading (m) environment. Multipath interference (MPI) and multi-access interference (MAI) is taken into account and the spectral efficiency is calculated for uncoded as well as channel coding systems. Predetection multipath maximal ratio combining (MRC) diversity in conjunction with interleaved channel coding (Hamming(7,4) code, BCH(15, 7) code and RS (7, 4), (15, 9)) code ) is employed for improving the bit error rate (BER) performance. The BER of noncoherent hybrid system is obtained using a Gaussian interference approximation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2173-2183
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• 1998

We consider a frequency-hopped multiple-access communication system that employs reed-solomon code over GF(Q) and M-ary FSK signaling ($M{\leq}Q$) in rayleigh fading channel. We investigate the tradeoff among the modulation symbol size (M), the number of frequency slots, and the code rate in maximizing the average number of successfully transmitted information bits per unit time and unit bandwidth (called normalized throughput). We find that it is desirabel to use a large M in noise-limited environment. In interference-limited environment, it is more improtant to prevent errors (hits) by increasing the number of frequency slots than to correct them with formward error correction techniques or to reduce the error rate by increasing M.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.1
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• pp.24-36
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• 2002

It is important to use frequency resource effectively to support much more users, to maximize the DS-CDMA system performance. In this paper, we use MPSK, QAM, MFSK and PR coder as a baseband modulation method for DS-CDMA system. Increasing user's number, we compare the performance of each system using different baseband modulation method, by expecting BER performance. BPSK has generally good performance, in case of low power operation of terminal 8FSK has excellent performance relatively, PR has excellent performance when high power operation of terminal and also good for situation of excessive user's number. QAM is not suitable for DS-CDMA system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4808-4824
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• 2016

Signal individual reconnaissance and identification is an extremely important research topic in non-cooperative domains such as electronic countermeasures and intelligence reconnaissance. Facing the characteristics of the complexity and changeability of current communication environment, how to realize radiation source signal individual identification under the low SNR conditions is an emphasis of research. A novel emitter individual identification method combined bi-spectrum analysis with wavelet feature is presented in this paper. It makes a feature fusion of bi-spectrum slice characteristics and energy variance characteristics of the secondary wavelet transform coefficient to identify MFSK signals under the low SNR (signal-to-noise ratios) environment. Theoretical analyses and computer simulation results show that the proposed algorithm has good recognition performance with the ability to suppress noise and interference, and reaches the recognition rate of more than 90% when the SNR is -6dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1005-1015
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• 2000

In this paper, the performance of Hybrid CDU MFSK system has been analyzed in the environment that narrowband Class-A impulsive noise include Gaussian noise in wireless communication channel and Nakagami fading. The performance of system improved to adopting both of technique MRC diversity and BCH channel coding. The results show that there is substantial degraded in Hybrid CDMA system performance by impulse index is stronger and the fading index is smaller. But also improvement can be obtained when BCH coding techniques are adopted. Additional MRC diversity techniques is more improvement than BCH coding techniques when degraded environment with the low fading index. But BCH coding techniques is more improvement than MRC diversity techniques when fading index has been increased. The Hybrid CDMA MFSK system is incomplete to voice communication standard BER$(10^{-3})$ in Rayleigh fading by independent each adopting techniques BCH coding and MRC diversity. But it's satisfy(improvement can be obtained) to voice communication standard BER in strong impulse noise(24dB over) by adopting techniques BCH coding and MRC diversity at a time. Additional it's a substantial enhancement $(10^{-3})$satisfaction) in fading index (m=3, 22dB) in addition to strong impulse noise and 24dB over with data service standard $(10^{-5})$ BER satisfaction. This result show that there is error performance improved by diversity branch and coding advantage.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.04a
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• pp.1-3
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• 1986

We are concerned with transmitting numerical source data of {0, 1, 2, ..., 2k-1} through a channel coding system. The rate 1/v dual-k convolutional code with the orthogonal MFSK modulation and the Viterbl decoding is employed for the implementation of the channel coding system. The mean square error of the dual-k convolutional code is evaluated for the numerical source transmitted over an additive white Gaussian noise channel with Rayleigh fading.