• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2473-2483
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• 2000

In this paper, The turbo code is used to effectively remove noise which is generated on the image communication channel. Turbo code had excellent decoding performance. However, it had limitations for real time communication because of the system complexity and time delay in decoding procedure. To overcome this problem, this paper proposed a new SRI(Semi Random Interleaved algorithm, which decrease the time delay, when the image data, which reduced the interleaver size of turbo code encoder and decoder, transmitted. The SRI algorithm was composed of 0.5 interleaver size from input frame sequence. When the data inputs in interleaver, the data recorded by row such as block interleaver. But, When the data read in interleaver, the data was read by randomly and the next data located by the just address simultaneously. Therefore, the SRI reduced half-complexity when it was compared with pre-existing method such as block, helical, random interleaver. The image data could be the real time processing when the SRI applied to turbo code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.164-169
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• 2009

This paper presents a fast and accurate ranging algorithm for the WiBro system. The proposed algorithm detects a received ranging code and estimates its propagation delay using the correlation characteristics of the PRBS (Pseudo Random Binary Sequence) and the circular shift property of the discrete Fourier transform operator. The proposed ranging algorithm was applied to array antenna systems to show how it could improve the ranging performance of an array antenna system compared to a conventional base station system, which uses only a single antenna.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.2
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• pp.10-21
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• 1998

In this paper, we analyze the anynchrous cellular hybrid DS/FH spread spectrum system with diversity on nonselective Nakagami fading channel. Binary Psk scheme is considered and random spreading code sequences and random hopping patterns are used. We compare the performance of system using hard-limiting correlation receiver with diversity and linear corrleation receiver in Nakagami fading channel. We compute the average bit error probabilities with/without diversity according to spreading code sequence and the number of hop-ping frequencies under the same handwith espansion, and analyze near-far effect. The results show that hard-limiting correlation receiver with diversity gives a good performance over severe fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6B
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• pp.1068-1073
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• 2000

In this paper, we propose a serially concatenated turbo bode/turbo equalizer scheme for optical storage systems. Without modulation coding, a random data sequence is directly passed through the optical channel. In simulation, the channel includes jitter of 15% and AWGN. The densities of the channel are S=4.6 and S=7.0. The code rates of turbo code are 4/5, 8/9 and 16/17. All code rates, the bit error probability is less than 10-5 at 24dB when we and jitter of 15%.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.501-504
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• 2000

In this paper, performance of a pseudonoise (PN) code tracking loop is analyzed and simulated for a direct-sequence/code-division multiple access ( DS/CDMA) system with imperfect power control in a multipath fading channel. A noncoherent first-order delay-locked loop (DLL) is considered as a PN code tracking loop. Power control error is modeled as a log-normally distributed random variable. From the simulation results, it is shown that for smaller discriminator offset, tracking jitter performance is improved while MTLL performance is degraded. It is shown that large power control error and heavy shadowing substantially degrade the PN tracking performance. The analysis in this paper can be applicable to design of PN code tracking loop for a DS/CDMA system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.951-958
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• 1999

Multicarrier modulation or orthogonal frequency division multiplexing(OFDM) is a promising technique for mobile communications systems, since it has a strong immunity to multipath fading without employing complicated adaptive equalization. In this paper, performance of MC DS-CDMA/MPSK(multi-carrier direct sequence-code division multiple access/mary phase shift keying) and DS-CDMA/MPSK(direct sequence-code division multiple access/mary phase shift keying) with coherent detection for a CDMA system over Nakagami fading channel analysis. For a given bandwidth, it is shown that MC DS-CDMA/MPSK eventually outperforms DS-CDMA MPSK with random sequences.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.666-674
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• 2005

A hybrid multicarrier CDMA/FDM system with a truncated adaptive transmission scheme is analyzed in forward link based on the feedback information from the mobile station. In the single cell environment, the prop(mea scheme outperforms the adaptive FH/DS system as well as the MC DS/CDMA system when orthogonal signature sequences are used. In the multiple cell environment also, the proposed scheme has better performance characteristics than the adaptive FH/DS system when orthogonal and random codes are used as spreading sequences.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.11a
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• pp.127-135
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• 1997

In this paper, we apply a digital modulation scheme called Multi-Carrier Code Division Multiple Access (MC-CDMA) in which data symbols are transmitted at multiple subcarriers. Each subcarrier is encoded with a phase offset of -π or π based on a pseudo-random noise(PN) sequence. MC-CDMA scheme is introduced to combat against the multipath fading. We annalize above system and derive the average probability of error in AWGN and Rayleigh fading environment.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.1-9
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• 1987

In this paper, the acquisition performance of a receiver that utilizes a non-coherent digital correlator is analyzed. In order to analyze the acquisition performance, the probability density function of a receiver output random variable has been derived approximately. Using this function, the acquisition performance of the coarse acquisition code receiver in a global positioning system is analyzed.

• Journal of Korea Multimedia Society
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• v.16 no.3
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• pp.318-329
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• 2013

This paper proposes a DNA watermarking method for the privacy protection and the prevention of illegal copy. The proposed method allocates codons to random circular angles by using random mapping table and selects triplet codons for embedding target with the help of the Lipschitz regularity value of local modulus maxima of codon circular angles. Then the watermark is embedded into circular angles of triplet codons without changing the codes of amino acids in a DNA. The length and location of target triplet codons depend on the random mapping table for 64 codons that includes start and stop codons. This table is used as the watermark key and can be applied on any codon sequence regardless of the length of sequence. If this table is unknown, it is very difficult to detect the length and location of them for extracting the watermark. We evaluated our method and DNA-crypt watermarking of Heider method on the condition of similar capacity. From evaluation results, we verified that our method has lower base changing rate than DNA-crypt and has lower bit error rate on point mutation and insertions/deletions than DNA-crypt. Furthermore, we verified that the entropy of random mapping table and the locaton of triplet codons is high, meaning that the watermark security has high level.