• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.25-34
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• 2024

The Satellite Based Augmentation System (SBAS) improves the accuracy and reliability of user positioning by transmitting the error correction and integrity information of the global navigation satellite system signal from geostationary satellites in real time. For this reason, SBAS was designed for aircraft operations and approach procedures and is now in operational or development stages in many countries. Time has passed since the construction of SBAS and many changes have occurred in the composition of the monitoring stations and the geostationary satellites. These changes have been investigated and the current operation and development status of SBAS globally are surveyed. The development and test schedules for the transition to dual frequency multi-constellation, an important topic in SBAS, are discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10C
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• pp.1010-1015
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• 2009

In this paper, we propose a novel detection ordering technique for MIMO signal detection methods based on QR decomposition and successive interference cancellation (SIC). Recently, new signal detection methods for spatially multiplexed (SM) MIMO systems were proposed, where all the constellation points are tried as the first layer symbol, and the remaining layer symbols are estimated via SIC, producing candidate vectors. Finally, the ML metric values are calculated for the candidate vectors, that are again used to select the best symbol vector. It was also shown that the ordering method in the conventional V-BLAST is not suitable to these signal detection methods. In this paper, we propose a novel ordering method, and we show via computer simulations that the proposed ordering method improves the error performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.109-114
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• 2015

This paper relates with the eualization performance of Adaptive Varying-MMA (AV-MMA) in order to the minimization of intersymbol interference that is occurs in the nonlinear communication channel. In order to obtain the error signal in the tap coefficient updating process of adaptive equalization algorithm, the present MMA uses the constant modulus. But in AV-MMA, the adaptively varying modulus are used according to the equalizer output, it is possible to reduce the error signal and possbile to improving the overall equalization performance. In order to improved equalization performance of the AV-MMA in the 64-QAM signal, the present MMA performance were compared. For this, the output signal constellation of equalizer, residual isi, maximum distortion, MSE and SER curves are applied. As a result of computer simulation, the AV-MMA has more better performance in the every performance index than MMA, and the SER performance shows that it has more robustness in high SNR environmnet compared to MMA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1833-1839
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• 2014

In this paper, a systematic demapping algorithm for three-dimensional (3-D) lattice signal constellations is presented. The algorithm consists of decision of an octant, computation of a distance from the origin, and determination of the coordinates of a symbol. Since the algorithm can be extended systematically, it is applicable to the larger lattice constellations. To verify the algorithm, 3-D signal transmission systems with field programmable gate array (FPGA) and $Matlab^{(R)}$ are implemented. And they are exploited to carry out computer simulation. As a result, both hardware and software based systems produce almost the same symbol error rates (SERs) in an additive white Gaussian noise (AWGN) environment. In addition, the hardware based system implemented with an FPGA generates waveforms of 3-D signals and recovers the original binary sequences perfectly. Those results confirm that the algorithm and the implemented 3-D transmission system operate correctly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.57-62
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• 2019

This paper evaluates the QE-MMA (Quantized Error-MMA) adaptive equalization algorithm by the number of quantizer in order to compensates the intersymbol interference due to channel in the transmission of high spectral efficient nonconstant modulus signal. In the adaptive equalizer, the error signal is needed for the updating the tap coefficient, the QE-MMA uses the polarity of error signal and correlation multiplier that condered nonlinear finite bit power-of-two quantizing component in order to convinience of H/W implementation. The different adaptive equalization performance were obtained by the number of quantizer, these performance were evaluated by the computer simulation. For this, the equalizer output signal constellation, residual isi, maximum distortion, MSE, SER were applied as a performance index. As a result of computer simulation, it improved equalization performance and reduced equalization noise were obtained in the steady state by using large quantizer bit numbers, but gives slow in convergence speed for reaching steady state.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.85-90
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• 2019

This paper related with the M-CMA adaptive equalization algorithm which is possible to improve the residual isi and robustness performance compare to the current MMA algorithm that is reduce the intersymbol interference occurs in channel when transmitting the QAM signal. The current MMA algorithm depend on the cost function and error function using fixed signal dispersion constant, but the M-CMA algorithm depend on the new proposed cost function and error function using multiple dispersion constant. By this, it is possible to having robustness of the CMA and simultaneous compensation of amplitude and phase of MMA. The computer simulation was performed in the same channel and noise environment for compare the proposed M-CMA and current MMA algorithm. The equalizer output signal constellation, residual isi, MD, MSE learning courves and SER, represents the robustness were used for performance index. As a result of simulation, the M-CMA has more superior to the MMA in robustness and other performance index.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.662-673
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• 2019

This paper investigates the most recent status of multi-GNSS, including technical features, types of ranging signals provided, and satellite constellation. Furthermore, a series of multi-GNSS positioning experiments in SPP mode were carried out to assess the achievable accuracy and continuity with an application to various positioning scenarios. A week of GNSS measurements each in 2018 and 2019 was acquired from the national geographical information institute and processed. The results show that a single GNSS-based scenario often encounters positioning blockage in the harsh operational environment, while multi-constellation cases are able to remedy this situation. The accuracy of multi-GNSS with a combination of GPS and Galileo is superior to that of other GNSS compositions due to the larger SISRE (Signal In Space Ranging Errors) of GLONASS and Beidou. Due to the different characteristics of GNSS SISRE, an issue has been raised to optimally integrate satellite measurements to maximize accuracy of multi-GNSS positioning.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.17-24
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• 2009

This paper deals with the cancellation performance of loop back interference signal in the case of multihop relay of 16-QAM received signal at the USN radio network. For this, it is necessary to the exchange of information with long distance located station by means of the relay function between the node in the USN environment. In the relay node, the loop-back interference signal which the retransmitting signal is feedback to the receiver side due to the antenna of transmitter and receiver are co-used or very colsely located or using the nonlinear device. Due to this signal, the performance of USN system are degraded which are using the limited resource of frequency and power. For improve this, it is necessary to applying the adaptive signal processing algorithm in order to cancellating the unwanted loop-back interference signal at the frontend of receiver in relaying node, we can get the better system and multi hop performance. In the adaptive signal processing, we considered the 16-QAM signal which has a good spectral efficiency, firstly, than, the QR-Array RLS algorithm was used that has a fairly good convergence property and the solving the finite length problem in the H/W implementation. Finaly, we confirmed that the good elimination performanc was confirmed by computer simulation in the learing cuved and received signal constellation compared to the conventional RLS.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.95-100
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• 2020

This paper related with the performance evaluation of mSE-MMA (modified Signed Error-Multi Modulus Algorithm) adaptive equalization algorithm which is possible to reduce the distortion that is occurs in nonlinear communication channel like as additive noise, intersymbol interference and fading. The SE-MMA algorithm are emerged in order to reducing the computational load compared to the presently MMA algorithm, it has the degraded equalization performance by this. In order to improve the performance degradation of SE-MMA, the mSE-MMA controls the step size according to the existence of arbitrary radius circle of equalizer output is centered at transmitted symbol point. The performance of proposed mSE-MMA algorithm were compared to present SE-MMA using the same channel and noise environment by computer simulation. For this, the recoverd signal constellation which is the output of equalizer, residual isi and MD (Maximum Distortion), MSE learning curve which is represents the convergence performance and SER which is represents the roburstness of noise were used as performance index. As a result of simulation, the mSE-MMA has more superior to the SE-MMA in every performance index, and was confirmed that mSE-MMA has roburstness to the noise in the SER performance than SE-MMA especially.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.1
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• pp.10-18
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• 2013

Recently, a fixed complexity LR(fcLR) technique was proposed. Also QR-LRL signal detection method was proposed in which all constellation symbols are tried as the symbol corresponding to the least reliable layer (LRL), thereby achieving high error performance. In this paper, we combine these two efficient methods to propose a novel detection method. When the LRL is disregarded in the process of LR, the worst case complexity of LR is significantly reduced. Also, the proposed method is shown to be superior to the conventional fcLR-based detection method from the perspective of error performance. Simulations are performed to demonstrate the efficacy of the proposed method.