• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12C
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• pp.753-758
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• 2011

The constant modulus algorithm (CMA) widely used in blind equalization applications minimizes the averaged power of constant modulus error (CME) defined as the difference between an instant output power and a constant modulus. In this paper, a decision feedback version of the linear blind algorithm based on maximization of the zero-error probability for CME is proposed. The Gaussian kernel of the maximum zero-error criterion is analyzed to have the property to cut out excessive CMEs that may be induced from severely distorted channel characteristics. Decision feedback approach to the maximum zero-error criterion for CME is developed based on the characteristic that the Gaussian kernel suppresses the outliers and this prevents error propagation to some extent. Compared to the linear algorithm based on maximum zero-error probability for CME in the simulation of blind equalization environments, the proposed decision feedback version has superior performance enhancement particularly in cases of severe channel distortions.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.999-1000
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• 2006

The LDPC Code is focusing a powerful FEC(Forward Error Correction) codes for 4G Mobile Communication system. LDPC codes are used minimizing channel errors by modeling AWGN Channel as VDSL system. The performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. LDPC code are encoded by sparse parity check matrix. there are decoding algorithms for a LDPC code, Bit Flipping, Message passing, Sum-Product. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten.

• Journal of Industrial Technology
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• v.25 no.A
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• pp.183-189
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• 2005

In precision instrumentation system, an A/D conversion of signal conditioning has some problems.; offset and drift errors with environmental situation. This paper suggested a development of the Multi-Channel A/D Data Acquisition System and a method of the evaluation and the temperature compensation for the A/D converters with the specific analog and digital circuit including the software. Also, we have designed a hardware and a software filters with smart algorithm for better signal processing of the proposed system. Software approach was adopted to obtain the stable data from A/D converter. As shown in our experimental works, the proposed system is expected to be used in the industrial field where a high precision measurement is required.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.177-178
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• 2007

WiBro system provides reliable broadband communication services for mobile and portable subcribers. It allows interference-free reception under the conditions of multipath propagation and transmission errors. Thus, powerful channel-error correction ability Is required. CC/CTC Decoder which Is mandatory for WiBro system needs lots of computations for real-time operation. So, it is desired to design a CC/CTC Decoder having highly optimized hardware scheme for low latency operation under high data rates. This paper proposes an efficient CC/CTC Decoder structure for high data rate WiBro system. Particularly, the proposed CTC Decoder architecture reduces decoding delay by applying pipelining and multiple decoding blocks. Simulation results show that reduction of about 80% of processing time is enabled with the proposed CC/CTC Decoder despite of increase in are.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.6
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• pp.296-301
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• 2006

Even though the emergency telecommunication make possible that specialist offers medical care over emergency cases in moving vehicle, we still have many problems in transmitting the image or video of patient over several wireless networks. To alleviate the effect of channel errors on compressed video bit-stream, this paper analyzed the error resilient features of JPEG2000 standard and measured the quality of transmission over noisy wireless channel, CDMA2000 1xEV-DO networks, compared to the features of error resilient tool of MPEG-4. We also proposed the optimum solution of transmitting images over real 3G network using JPEG2000 error resilient tool.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1102-1109
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• 2001

This paper presents the new architecture of an adaptive predistortion linearizer using the polynomial type predistorter. In the proposed linearizer, most of the processes, including the predistortion, are performed with a digital signal processor(DSP). The recursive least squares(RLS) algorithm is employed for the optimization process to minimize the errors between the predistorter and postdistorter output signals. Simulation results demonstrate that the adjacent channel power ratio(ACPR) is improved by greater than 40 dB at the band edge with linearization. The convergence and reconvergence performance of the linearizer is also satisfactory.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.49-52
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• 2003

OFDM(Orthogonal Frequency Division Multiplexing) scheme can compensate for distortions caused by multipath delay spread and reduce the burst errors caused by the Doppler effect since OFDM signals have long symbol durations. However, OFDM is required to be improved for high speed data transmission and large capacity. Therefore, coding schemes should be combined with OFDM. In this paper, it was studied that the performance of OFDM transmission scheme was improved in mobile communication channel by applying TCM, which has advantages of error correction and bandwidth efficiency. Simulation was carried out for two TCM models with different code efficient length. By mapping two models to square 16QAM, the model with the code efficient length of 2 achieved 3dB better than the other for the BER of 10/sub -3/. In conclusion, if we want to achieve a better performance with TCNA in OFDM applications, we should select a TCM with larger code efficient length.

• ETRI Journal
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• v.28 no.4
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• pp.435-443
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• 2006

This paper presents an efficient carrier recovery algorithm combined with a turbo-coding technique in a mobile communication system. By using a block turbo code made up of independently decodable block codes, we can efficiently recover the fast time-varying carrier phase as well as correct channel errors. Our simulation results reveal that the proposed scheme can accommodate mobiles with high speed, and at the same time can reduce the number of iterations to lock the phase.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.79-82
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• 1986

For the purpose of error correcting, a concatenated coding system has been proposed by cascading two codes-(7, 3) Reed-Solomon and (2, 1, 6) convolutional codes. As a result of the result of the computer simulation and the experiment, the (98.21) concatenated code has been show to be able to correct 12 randome error and 16 bust errors. When the channel error is about 1.2x10, this system indicats most efficient.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1229-1232
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• 2003

In this paper, The High-speed Low-power Analog-to-Digital Convener Archecture is proposed using the parallel S/H for High-speed operation. This technique can significantly reduce the sampling frequency per S/H channel. The Analog-to-Digital Converter is designed using 0.35${\mu}{\textrm}{m}$ CMOS technology. The simulation result show that the proposed Analog-to-Digital Converter can be operated at 40Ms/s with 8-bit resolution and INL/DNL errors are +0.4LSB~-0.6LSB / +0.9LSB~-1.4LSB , respectively.