• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.71-76
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• 2000

A TC-16ADPSK scheme for transmitting different kinds of information simultaneously is proposed in this paper. The scheme is designed for simultaneously transmitting two kinds of Information on one channel. In signal mapping, a data of two kinds of information is used to phase modulation on Star-16APSK constellation and the other to amplitude modulation. In detection, each data independently recovers from mixing signal on each detector Therefore, we can transmit two kinds of Information on one channel can be transmitted efficiently. BER performance of the proposed scheme is analyzed on AWGN channel and Rayleigh fading channels on a computer with Matlab communication toolbox. On same SNR, the Gray code mapping has more 0.5-1.5dB coding gains than Ungerboeck's code mapping gains.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.178-203
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• 2018

In this paper, authors have been evaluated the Frame Error Rate (FER) performance of IEEE 802.11 a/g/p standard 5 GHz frequency band WLAN over Rayleigh and Rician distributed fading channels in presence of Additive White Gaussian Noise (AWGN). Orthogonal Frequency Division Multiplexing (OFDM) based transceiver is implemented by using real-time signal processing frameworks (IEEE 802.11 Blocks) in GNU Radio Companion (GRC) and Ettus USRP N200 is used to process the symbol over the wireless radio channel. The FER is calculated for each sub-carrier conventional modulation schemes used by OFDM such as BPSK, QPSK, 16, 64-QAM with different punctuated coding rates. More precise SNR is computed by modifying the SNR calculation process of YANS and NIST error rate model to estimate more accurate FER. Here, real-time signal constellations, OFDM signal spectrums etc. are also observed to find the effect of multipath propagation of signals through flat and frequency selective fading channels. To reduce the error rate due to the multipath fading effect and Doppler shifting, channel estimation (CE) and equalization techniques such as Least Square (LS) and training based adaptive Least Mean Square (LMS) algorithm are applied in the receiver. The simulation work is practically verified at GRC by turning into a pair of Software Define Radio (SDR) as a simultaneous transceiver.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.69-75
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• 2004

In the paper, system is combined multiband system with DS-UWB techniques with properties including low peak-to-average power ratio, robustness to multiuser interference and excellent security. Because each sub-band is not satisfied with coherence bandwidth, rake receiver in each sub-band is applied to the Proposed system receiver. Output of rake receiver is combined by using Maximal Ratio combining technology. In this paper we mathematically analyse the BER of the DS-UWB system with singleband and multiband systems in the narrow interference channel condition and multi user interference channel condition, the simulation results show that proposed scheme is getting robuster with increasing of the number of subbands.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.16-22
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• 2012

In this paper, the forensic marking algorithm is proposed using psychoacoustic model II and MDCT for high-quality audio. The proposed forensic marking method, that inserts the user fingerprinting code of the audio content into the selected sub-band, in which audio signal energy is lower than the spectrum masking level. In the range of the one frame which has 2,048 samples for FFT of original audio signal, the audio forensic marking is processed in 3 sub-bands. According to the average attack of the fingerprinting codes, one frame's SNR is measured on 100% trace ratio of the collusion codes. When the lower strength 0.1 of the inserted fingerprinting code, SNR is 38.44dB. And in case, the added strength 0.5 of white gaussian noise, SNR is 19.09dB. As a result, it confirms that the proposed audio forensic marking algorithm is maintained the marking robustness of the fingerprinting code and the audio high-quality.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.347-355
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• 2000

This paper presents an adaptive AEC(acoustic echo canceller) based on the wavelet transform using M-channel subband QMF filter banks. The proposed algorithm improves the performance of AEC with a realtime process by a low complexity of wavelet transform filter banks, a subband processing and a orthogonality of wavelet subband filter. Adaptive filter coefficients of each subband are updated using LMS algorithm with a low complexity and a easy realization for a realtime processing and a reduction of hardware cost. For a input signal, a white Gaussian noise and a real speech signal with a environment noises are used for a performance estimation of the proposed algorithm. As a result of computer simulation, the proposed AEC has a low asymptotic error, a low computation complexity and a robust performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.10
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• pp.912-920
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• 2012

In this paper, we derived a closed-form equation of a Best Linear Unbiased Estimator (BLUE) estimator for the 3 dimensional estimation of the position of the emitter based on the Time Difference of Arrival (TDOA) technique. The BLUE derived for the case of estimating 3 dimensional position of the emitter with 4 base stations or sensors, and for this purpose, we used an approximated equation of the TDOA hyperbola equation obtained from the first order Taylor-series after setting the reference points of the position. The derived equation can be used for any kind of noises which are uncorrelated in each other in the TOA measurement noises and for a white Gaussian noise also.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.330-335
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• 2002

In the direct sequence code division multiple access system, the problem of multiple access interference due to multiple access is generated. A interference cancelling receiver is used to solve this problem. The conventional interference cancelling receiver is structure of successive interference canceller using antenna array. In this structure, the difference of between method I and method II depends on updating weight vector. In this paper, the adaptive blind CMA array interference cancelling receiver using cost function of constant modulus algorithms is proposed to update weight vector at conventional structure. The simulation compared the proposed interference cancelling receiver with two conventional interference cancelling receivers by signal to interference ratio and bit error rate curve under additive white Gaussian noise environment. The simulation results show that the proposed receiver has about the gain of SIR of 1.5[dB] more than method I which is conventional receiver at SIR curve, and about the gain of SIR of 0.5(dB) more than method II. In BER curve, the proposed IC receiver about the gain of SNR of 2[dB] more than method I and about the gain of SNR of 0.5[dB] more than method If, Thus, the proposed interference cancelling receiver has the higher performance than conventional interference cancelling receivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.8 no.3
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• pp.105-112
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• 1983

This paper discribes technique of the recursive restoration for the images degraded by linear space invariant blur and additive white Gaussian noise. The image is characterized statistically by tis mean and correlation function. An exponential autocorrelation function has been used to model neighborhood model. The vector model was used because of analytical simplicitly and capability to implement brightness correlation function. Base on the vector model, a two-dimensional discrete stochastic a 12 point neighborhood model for represeting images was developme and used the technique of moving window processing to restore blurred and noisy images without dimensionality increesing, It has been shown a 12 point neighborhood model was found to be more adequate than a 8 point pixel model to obtain optimum pixel estimated. If the image is highly correlated, it is necessary to use a large number of points in the neighborhood in order to have improvements in restoring image. It is believed that these result could be applied to a wide range of image processing problem. Because image processing thchniques normally required a 2-D linear filtering.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.669-677
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• 2003

A new Modem technique - 8SQAM(8-state Superposed Quadrature Amplitude Modulation) - for use in power and bandwidth limited digital communication system is proposed. 8SQAM is free of inter-symbol interference(ISI) and generates output signals which have a smooth and continuous phase transition and a reduced envelope fluctuation by keeping correlation between amplitudes and phases of two subsequent symbols. Accordingly, 8SQAM, as compared with a conventional 8PSK, is influenced a little by ISI and inter-modulation(IM) caused by nonlinear distortions. In this paper, the performance of the 8SQAM system, in a nonlinearly amplified channel impaired by additive white Gaussian noise(AWGN), ISI and IM, is analyzed via computer simulation. The simulation result shows that 8SQAM outperforms 8PSK with roll-off value of $\alpha$=0.25 by 2.5dB in CNR to maintain BER=1$\times$10$^{-4}$ when input back-off(IBO) of HPA is 3dB.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.17-22
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• 2008

Double-binary turbo code has been adopted as an error control code of various future communication systems including wireless metropolitan area networks(WMAN) due to its powerful error correction capability. One of the components affecting the performance of turbo code is internal interleaver. In 802.16 d/e system, an almost regular permutation(ARP) interleaver has been included as a part of specification, however it seems that the interleaver is not optimized in terms of decoding performance. In this paper, we propose three optimization methods for the interleaver based on spatial distance, spread and minimum distance between original and interleaved sequence. We find optimized interleaving parameters for each optimization method and evaluate the performances of the proposed methods by computer simulation under additive white Gaussian noise(AWGN) channel. Optimized parameters can provide up to 1.0 dB power gain over the conventional method and furthermore the obtainable gain does not require any additional hardware complexity.