• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.75-80
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• 2013

In this paper, the Ka-band maritime satellite communication systems for mobile terminals are proposed. The design includes the link budget analysis, determination of modulation and coding schemes and the overall structure of a transmitter. To avoid the harmful effects on the existing DVB-S2 services, the proposed maritime satellite system using the same spectrum with DVB-S2 at the same time employs the very wideband spreading transmission. Additionally, omni-directional low-gain antennas should be equipped in a mobile terminal to reduce the system cost. These two considerations limit the maximum transmission rate of the proposed system. Due to the limitations, the proposed system includes 36 dB or 39 dB spreading gain depending on the modulation scheme and a link-adaptive repetition method depending on the level of rain attenuation. To support short packets with minimal performance loss, the turbo code used in 3GPP instead of LDPC(low density parity check code) is adopted. By combining them, the overall structure of low-rate maritime satellite communication system is designed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.577-586
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• 2011

Modem digital communication systems are required to use forward error correction (FEC) codes to combat inevitable channel impairment. Turbo codes or low density parity check (LDPC) codes, using iterative decoding with soft decision detection (SDD) information, are the most common examples. The excellent performance of these codes should be conditioned on accurate estimation of soft decision detection information. In order to use FEC codes with iterative decoding for Multi-Input Multi-Output (MIMO) system, reliable soft decision channel gain should be provided. In this paper, we investigate efficient SDD methods for turbo-coded MIMO system, and derive the corresponding formulas of SDD for various MIMO detection schemes. We present simulation results of the derived SDD schemes for turbo-coded MIMO systems, and show that the presented results almost approximate to maximum likelihood detection performance with much less computational load.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.4149-4154
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• 2016

Background: Cervical carcinoma is one of the main causes of mortality in women worldwide as well as in India. It occurs as a result of various molecular events that develop from the combined influences of an individual's genetic predisposition and external agents such as smoking and menstrual hygiene, for example. However, infection with human papillomavirus (HPV) is the established major risk factor. The aim of the current study was to investigate p16 CpG island methylation and establish any correlation with mRNA expression in north Indian population. Materials and Methods: We analyzed 196 woman volunteer out of which 98 were cases and 98 healthy controls. For the analysis of methylation pattern, DNA extracted from blood samples was modified with a bisulfate kit and used as template for methylation specific PCR (MSP). Quantitative real-time PCR (QRT-PCR) was performed to check mRNA expression. Results: Correlation between methylation status of p16 gene and poor menstrual hygiene was significant (p=0.006), high parity cases showed methylation of p16 gene (p=0.031) with increased risk up to 1.86 times for cervical cancer and smoking was a strong risk factor associated with cervical cancer. We analyzed methylation pattern and found 60.3% methylation in cases with low mRNA expression level (0.014) as compare to controls (1.24). It was also observed that promoter methylation of p16 gene was significantly greater in FIGO stage III. Conclusions: We conclude that p16 methylation plays an important role in cervical cancer in the north Indian population and its methylation decreases mRNA expression. It can be used as an important and consistent blood biomarker in cervical cancer patients.

• Convergence Security Journal
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• v.12 no.4
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• pp.85-90
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• 2012

DES is a 64-bit binary, and each block is divided into units of time are encrypted through an encryption algorithm. The same key as the symmetric algorithm for encryption and decryption algorithms are used. Conversely, when decryption keys, and some differences may apply. The key length of 64 bits are represented by two ten thousand an d two 56-bit is actually being used as the key remaining 8 bits are used as parity check bits. The 64-bit block and 56-bit encryption key that is based on a total of 16 times 16 modifier and spread through the chaos is completed. DES algorithm was chosen on the strength of the password is questionable because the most widely available commercially, but has been used. In addition to the basic DES algorithm adopted in the future in the field by a considerable period are expected to continue to take advantage of the DES algorithm effectively measures are expected to be in the field note.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.4
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• pp.80-87
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• 2007

In this paper, link-level performance of a OFDMA technique, which has been considered as a standard for 802.16, 802.20, 3G-LTE, WiMax, and WiBro, is evaluated for next-generation wireless communication systems. While many researches have focused on uncoded forward-link performances, this paper provides a coded performance of a reverse-link OFDMA system. Performance degradation due to time offset among reverse-link users and frequency offset during FFT process is investigated. Transmitter and receiver antenna diversity techniques are used to overcome performance degradation. Performance of a OFDMA system is compared with a CDMA system in terms of FER and throughput to emphasize the advantage of OFDMA system for a reverse-link. Finally, under given specification, Eb/No required to achieve the maximum throughput of a reverse-link is proposed considering various coded rates and antenna permutations.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.42-49
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• 2016

This paper proposes a low-complexity generator which finds the first two minimum values using bit-serial scheme. A low-complexity generator is an important part for low-area LDPC decoders based on the min-sum decoding algorithm because the hardware complexity of generators utilizes a significant portion of LDPC decoders. To reduce hardware complexity, bit-serial LDPC decoders has been studied. The generator of the existing bit-serial LDPC decoders can find only the first minimum value, and thus it leads to a BER performance degradation. The proposed generator using bit-serial scheme finds the first two minimum values. Hence, it can improve the BER performance. In addition, the area-time complexity of the proposed generator is lower than those of the existing generators finding the first two minima.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.80-86
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• 2006

The wireless communication based on LDPC and adaptive spatial-subcarrier coded modulation using MQAM for orthogonal frequency division multiplexing (OFDM) wireless transmission by using instantaneous channel state information and employing multiple antennas at both the transmitter and the receiver. Adaptive coded modulation is a promising idea for bandwidth-efficient transmission on time-varying, narrowband wireless channels. On power limited Additive White Gaussian Noise (AWGN) channels, low density parity check (LDPC) codes are a class of error control codes which have demonstrated impressive error correcting qualities, under some conditions performing even better than turbo codes. The paper demonstrates OFDM with LDPC and adaptive modulation applied to Multiple-Input Multiple-Output (MIMO) system. An optimization algorithm to obtain a bit and power allocation for each subcarrier assuming instantaneous channel knowledge is used. The experimental results are shown the potential of our proposed system.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.3-7
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• 2017

Holographic data storage system (HDSS) features short access times, high storage capacities, and fast transfer rates, since the data is recorded and read not by lines but by pages within a volume of holographic material. Burst error caused by physical impact on the high density storage system becomes very longer than that of conventional storage systems. This paper proposes an LDPC product code using two LDPC code to resolve burst error. When a total code rate is similar, the performance of two LDPC code having high code rate is better than that of one LDPC code having low code rate. Also, with error factors of two-dimensional intersysbol interference and misalignment, the proposed scheme can improve the performance in holographic data storage system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.63-69
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• 2017

In next generation satellite broadcasting system, requirement of high throughput efficiency has been increasing continuously. To increase throughput efficiency and improve bit error performance simultaneously, FTN method and LDPC codes are employed in new sattelite standard, DVB-S3 system. This paper considered three kinds of methods for increase throughput efficiency. Firstly, as conventional one, high coding rate parity matrix in LDPC encoder is considered. Secondly, punctured coding scheme which delete the coded symbols according to appropriate rules is considered. Lastly, FTN method which transmit fater than Nyquist rate is considered. Among of three kinds of methods, FTN method is most efficient in aspect to performance while maintain same throughput efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.504-511
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• 2016

In this paper, MIMO system based on turbo equalization techniques which LDPC codes were outer code and space time trellis codes (STTC) were employed as an inner code are studied. LDPC decoder and STTC decoder are connected through the interleaving and de-interleaving that updates each other's information repeatedly. In conventional turbo equalization of MIMO system, BCJR decoder which decodes STTC coded bits required two-bit wise decoding processing. Therefore duo-binary turbo codes are optimal for MIMO system combined with STTC codes. However a LDPC decoder requires bit unit processing, because LDPC codes can't be applied to these system. Therefore this paper proposed turbo equalization for MIMO system based on LDPC codes combined with STTC codes. By the simulation results, we confirmed performance of proposed turbo equalization model was improved about 0.6dB than that of conventional LDPC codes.