• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.405-409
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• 2009

In this paper, the effects of LLR (Log-Likelihood Ratio) approximation on LDPC (Low-Density Parity-Check) decoder performance are analyzed, and optimal design conditions of LDPC decoder are derived. The min-sum LDPC decoding algorithm which is based on an approximation of LLR sum-product algorithm is modeled and simulated by MATLAB, and it is analyzed that the effects of LLR approximation bit-width and maximum iteration cycles on the bit error rate (BER) performance of LDCP decoder. The parity check matrix for IEEE 802.11n standard which has block length of 1,944 bits and code rate of 1/2 is used, and AWGN channel with QPSK modulation is assumed. The simulation results show that optimal BER performance is achieved for 7 iteration cycles and LLR bit-width of (7,5).

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.3
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• pp.52-60
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• 1983

This paper presents a complete analysis for the derivation of the probability of error for a fast (or multiple-hops per bit) frequency hopping spread spectrum system employing binary FSK modulation and noncoherent reception in the presence of partial-band noise jamming and thermal noise. The worst-case error rate performances were obtained numerically and presented as a function of E /N with L as a parameter, where E /N and L are the signal bit energy-to-jamiming density ratio and the number of hops per bit, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.37-43
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• 2008

The performance and hardware complexity of LDPC decoders depend on the design parameters of quantization, the clipping threshold $c_{th}$ and the number of quantization bits q, and also on the maximum number of decoding iterations. In this paper, the BER performances of LDPC codes are evaluated according to the clipping threshold $c_{th}$ and the number of quantization bits q through the simulation studies. By comparing the quantized Min-Sum algorithm with the ideal Min-Sum algorithm, it is shown that the quantized case with $c_{th}=2.5$ and q=6 has the best performance, which approaches the idea case. The decoding complexities are calculated and the word error rates(WER) are estimated by using the pdf which is obtained through the statistical analyses on the iteration numbers. These results can be utilized to tradeoff between the decoding performance and the complexity in LDPC decoder design.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.1-6
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• 2021

In this paper, in order to mitigate ISI(inter-symbol interference) in a diffusion-based molecular communication channel, an ISI Hamming code is proposed in which ISI characteristics are applied to a channel decoding algorithm. In order to prove the bit error rate performance of the proposed channel code, the bit error rate performance of the major channel codes applied to the molecular communication channel with ISI was compared and analyzed through simulation. From the simulation results, it can be seen that the bit error rate performance of the ISI Hamming code is the best when the number of radiated molecules is less than or equal to 1100. In addition, when the number of transmitted molecules is M=1000, the decoding method of the ISI Hamming code proposed in this paper has improved the bit error rate of approximately 5.9×10-5 compared to the Hamming code using only soft values. Compared with the ISI-mitigating channel code, which is effective for removing ISI in the molecular communication channel, the ISI Hamming code proposed in this paper is the most advantageous in a channel environment where the number of transmitted molecules is not big (M<1100). And we can see that the ISI-mitigating channel code is more advantageous when the number of transmitted molecules is large(M>1100).

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.213-221
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• 2006

In this paper, an improved detection method is proposed by supplementing various types of Proportional gam for a MMSE detecter. This method is proposed io complement the shortcomings of the conventional detection method which is used for multiuser detection in STBC(Space-Time Block Code) CDMA system. We analyzed the improved method in bit error probability viewpoint and compared the result with that of the conventional method. In this result, we showed that the Improved method obtains better performance of bit error probability than the conventional method when parameters such as delay, number of user and SNR are increased.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.145-154
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• 2007

In this paper, an improved detection method is proposed by supplementing various types of Multi-Path gam for a MMSE Multi-User detecter. This method is proposed to complement the shortcomings of the conventional detection method which is used for multiuser detection in STBC(Space-Time Block Code) CDMA system. We analyzed the improved method in bit error probability viewpoint and compared the result with that of the conventional method. In this result, we showed that the improved method obtains better performance of bit error probability than the conventional method when parameters such as delay, number of user and SNR are changed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.10
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• pp.1100-1108
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• 1992

The evaluation of coded error probabilities for antijam communication systems is usually difficult to do and, thus, easy-to-evaluate upper bounds are used. Since it is relatively easy to evaluate the cutoff rate for the coding channel, the coded bit error bounds for most antijam systems of interest can be easily expressed directly in terms of this cutoff rate parameter using the relationship between the bit error bounds and cutoff rate for AWGN channel. The key feature of these bounds is the decoupling of the coding aspects of the system from the remaining part of the communication system which includes jamming, suboptimum detectors, and arbitrary decoding metrics which may or may not use jammer state knowledge. In this paper the bit error bounds for the Trumpis coded FH/MFSK with an AWGN channel are translated into the corresponding bit error bounds for boradband and partial band noise jammer. And the impact of the side information about jammer state is also evaluated with these upper bounds. Although it is considered for the soft decision detector, it is also applicable to the hard decision detector.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.591-601
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• 1993

In this paper, the relationship between k consecutive outputs of the conventional differential detector and output of differential detector with k-bit delayer MSK and GMSK signal, using a k-bit delay circuit, is the product of k successive output of the conventional differential detector. This relationships are used to generalize the structure of receiver which was proposed by Makrakis using 2-bit delay line. The error rate performance of the proposed method is carried out by computer simulation and significant performance improvement is achieved for differential MSK and GMSK system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.309-315
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• 1998

This paper is analyzed the performance of coded MC-CDMA system using the multi-carrier with narrow band that is suggested to solve ISI and ICI of DS-CDMA system. In this paper, considered channel model is indoor mobile radio communication environment with Rician fading distribution and fading of multi-carrier have mutual independent characteristics. For the performance analysis of MC-CDMA system, first, bit error probability of uncoded system is simulated in the reverse and forward Rician channels. And then, it is simulated that bit error probability of coded MC-CDMA system for users, multicarriers and SNR, using (7,4) Hamming code, (15,7) BCH code and 1/2-convolutional code with 7 constraint length.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.901-911
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• 1994

The error performance of M-ary differential phase shift keying (MDPSK) through m-distribution fading channel in hybrid direct sequence/slow frequency hopped spread spectrum multiple access (DS/SFH-SSMA) systems has been evaluated, and also the error probability has been evaluate when adopting diversity technique and coding technique. From the results, we know that the error performance more deteriorates as depth of fading becomes deeper. In Rayleigh fading environment (m=1), increasing of the number of frequency hopping (q) reduces the effect of multiple access interference, because it decreases the probability a hit. When q is much larger than the number of user (K), the probability of error in high E/N region is dominated by the multipath interference while the multiple access interference is negligible. In lower E/N region, the probability of error is independent of q because the effect of gaussian noise becomes dominat.