• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.3
• /
• pp.47-53
• /
• 1998

Multi-dimensional DC-free trellis codes based on two-dimensional constellation which can be omplemented more easily than conventional codes are proposed and their performances are analyzed in this paper. 2N-dimensional constellation of the proposed codes is constructed by concatenating N 2-dimensional constellation. Thus, for the proposed codes, information bits can be assigned easily to each signal point of the 2-dimensional consteellation and DC-free characteristic can be simply obtained by the symmetric structure of the constellation. In addition, since Viterbi decoder can calculate multi-dimensional Euchlidean distance between signals by simple sum of each 2-dimensional Euclidean distanc, decoding complexity can be reduced. The performance analysis shows that the proposed codes have almost same spectral characteristic and error performance as compared with conventional codes. However, the complexity is shown to be reduced further due to the construction method of contellation and the simple decoding algorithm of the proposed codes.

• The Journal of Information Technology
• /
• v.1 no.2
• /
• pp.39-53
• /
• 1998

The CMA and MCMA adaptive blind equalization algorithm has an inevitable error caused by mismatching between the original constellation at the steady state after the equalization and the unique constellation. This problem is due to considering the new type constellation(constant modulus, reduced constellation) as desired constellation. In this paper, we propose a new adaptive blind equalization algorithm which can reach to the steady state with rapid convergence speed and achive the improvement of error value in the steady state. The Proposed algorithm has a new error function using the decided original constellation instead of the reduced constellation. By computer simulation, it is comfirmed that the proposed algorithm has the performance superiority in terms of residual ISI and convergence speed compared with the adaptive blind equalization algorithm of CMA family, Constant Modulus Algorithm with Carrier Phase Recovery and Modified CMA(MCMA).

• Proceedings of the Korea Contents Association Conference
• /
• 2005.11a
• /
• pp.649-653
• /
• 2005

To estimate for an error signal with sigmoid nonlinearity what reduced constellation applies closed eye pattern in the initial equalization, there can be improves problems of previous soft decision-directed algorithm that increasing estimate complexity and decreasing of convergence speed when substitute high-order constellation. The characteristic of sigmoid function is adjusted by a mean and a variance parameter, so it depends on adjustment of variance that what reduced constellation $values(\gamma)$ can have ranges between + $\gamma$ and - $\gamma$. In this paper, we proposed Variable Modulus Algorithm (VMA) that can be improving a performance of steady-state by adjustment of variance when equalization works normally and each cluster of constellation decrease.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.12A
• /
• pp.1339-1345
• /
• 2007

An important drawback in Lattice Reduction (LR) aided detectors has been investigated. For the solution, an improved LR aided detection with ignorable complexity overhead is proposed for MIMO system, where the additional correction operation is performed for the case of unreliable symbol decision. We found that LR aided detection errors mainly occur when the lattice points after the inverse lattice transform in the final step fall outside the constellation point set. In the proposed scheme, we check whether or not the lattice point obtained through LR detection is out of constellation. Only for the case of out of constellation, we additionally perform ML search with reduced search region restricted to the neighboring points near to the obtained lattice points. Using this approach, we can effectively and significantly improve the detection performance with just a slight complexity overhead which is negligible compared to full searched ML scheme. Simulation results show that the proposed scheme achieves the detection performance near to that of the ML detection with a lower computational complexity.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.6A
• /
• pp.473-479
• /
• 2012

In this paper, blind equalization technique using Gaussian two-cluster model is proposed. The proposed approach, by modeling the received M-QAM signals as Gaussian distributed two-cluster, minimizes the computational complexity and enhances the reliability of the signal estimates. In addition, by using a nonlinear estimator with variable parameters to estimate the transmitted signal, and by selectively applying the reduced constellation and the original constellation when estimating the signals, the reliability of the signal estimation was further improved. As a result, the proposed approach has improved the performance while reducing the complexity of the equalizer. Through computer simulations for blind equalization of higher-order signals of 64-QAM, it was confirmed that the proposed method showed better performance than traditional approaches.

• Journal of Positioning, Navigation, and Timing
• /
• v.8 no.1
• /
• pp.1-12
• /
• 2019

In this paper, we implement a navigation software of a Global Navigation Satellite System (GNSS) receiver based on a commercial purpose GNSS software receiver platform and verify its performance by performing experimental tests for various GNSS signals available in Korea region. The SX3, employed in this paper, is composed of an application program and a Radio Frequency (RF) frontend, and can capture and process multi-constellation and multi-frequency GNSS signals. All the signal processing procedure of SX3 is accessible by the receiver software designer. In particular for an easy research and development, the Application Programing Interface (API) of the SX3 has a flexible architecture to upgrade or change the existing software program, equipped with a real-time monitoring function to monitor all the API executions. Users can easily apply and experiment with the developed algorithms using a form of Dynamic Link Library (DLL) files. Thus, by utilizing this flexible architecture, the cost and effort to develop a GNSS receiver can be greatly reduced.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.5
• /
• pp.107-114
• /
• 2012

In this paper, the concerned existing blind equalizer convergence rate and residual inter-symbol interference using constellation reduced and cost function by separation the real part and an imaginary part, the dual structure CR-CMA(constellation Reduction CMA). The CMA methed compensates amplitude but does no compensate phase, On the other hand, The CMA method compensates both the amplitude and the phase but it has the convergence rate problem, and the MCMA method is a way to solve the phase problem of CMA method compensates both the amplitude and the phase after respectively calculating the real part and imaginary part components. Proposal a new method that the dual structure of CR-CMA, the cost function and error function and respectively calculating the real part and imaginary part components can advantages by improving the CMA and the MCMA algorithms so that the amplitude and phase retrieval and constellation reduce the residual ISI and faster convergence rate and performance is good SER (Symbol Error Ratio) was confirmed by computer simulations.

• The Journal of Information Technology
• /
• v.8 no.3
• /
• pp.105-115
• /
• 2005

The CMA and MMA blind equalization algorithm has the inevitable large residual error caused by mismatching between the symbol constellation at a steady state after convergence. Stop-and-Go algorithm has a very superior residual error characteristics at a steady state but a relatively slow convergence characteristics. In this paper, we propose a SAG-Flagged MMA as a new adaptive blind equalization algorithm with a Stop-and-Go flag which follows a flagged MMA in update scheme of tap weights as appling the flag obtaining from Stop-and-Go algorithm to MMA. Using computer simulation, it is confirmed that the proposed algorithm has an enhancing performance from the viewpoint of residual ISI, residual error and convergence speed in comparison with MMA and Stop-and-Go algorithm. Algorithm has a new error function using the decided original constellation instead of the reduced constellation. By computer simulation, it is confirmed that the proposed algorithm has the performance superiority in terms of residual ISI and convergence speed compared with the adaptive blind equalization algorithm of CMA family, Constant Modulus Algorithm with Carrier Phase Recovery and Modified CMA(MCMA).

• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.1
• /
• pp.51-58
• /
• 2023

Geofencing supports unmanned aerial vehicle (UAV) operation by defining stay-in and stay-out regions. National Aeronautics and Space Administration (NASA) has developed a prototype of the geofencing function, SAFEGUARD, which prevents stayout region violation by utilizing position estimates. Thus, SAFEGUARD depends on navigation system performance, and the safety risk associated with the navigation system uncertainty should be considered. This study presents a methodology to compute the safety risk assessment-based along-track position error bound under nominal and Global Navigation Satellite Systems (GNSS) failure conditions. A Kalman filter system using pseudorange measurements as well as pseudorange rate measurements is considered for determining the position uncertainty induced by velocity uncertainty. The worst case pseudorange and pseudorange rate fault-based position error bound under the GNSS failure condition are derived by applying a Receiver Autonomous Integrity Monitor (RAIM). Position error bound simulations are also conducted for different GNSS fault hypotheses and constellation conditions with a GNSS/INS integrated navigation system. The results show that the proposed along-track position error bounds depend on satellite geometries caused by UAV attitude change and are reduced to about 40% of those of the single constellation case when using the dual constellation.

• Korean Journal of Heritage: History & Science
• /
• v.46 no.2
• /
• pp.70-95
• /
• 2013

The Tejaprabha Buddha painting, located in the Korai Museum in Kyoto, Japan, was made in 1569 when Joseon Dynasty was in his $14^{th}$ year under SeonJo's ruling, and is only one of Tejaprabha Buddha paintings from the early Chosun dynasty. With its well preserved state, the painting allows clear indications of all icons and list of names that were written, and the record region also has minimal deterioration. This Buddhist painting is a GumSeonMyoHwa which is drawn with gold lining on red hemp cloth and has a relatively small dimension of $84.8{\times}66.1cm$. With the Tejaprabha Buddha in the center, the painting has two unidentified Bodhisattvas, Navagrabha, Rahu, Keto, YiSipPalSoo (28 constellation of the eastern philosophy), SipYiGoong (12 zodiacs of the western philosophy), SamDaeYookSung, and BookDooChilSung (the Big Dipper), all of which provide resourceful materials for constellation worshipin the Joseon era. This painting has a crucial representation of the overall Tejaprabha Buddhism - a type of constellation worships - from the early Joseon dynasty. Even though the composition does seem to be affiliated with the paintings from the Koryo dynasty, there are meaningful transformations that reflect changes in content into constellation worship in Joseon dynasty. As a part of the Tejaprabha Buddha, SipIlYo has become a center of the painting, but with reduced guidance and off-centered 'Weolpe (star)', the painting deteriorates the concept of SipIlYo's composition. Furthermore, addition of Taoistic constellation beliefs, such as JaMiSung (The purple Tenuity Emperor of the North Pole), OkHwangDaeChae, and CheonHwangJae, eliminates the clear distinction between Taoistic and Buddhist constellation worships. Unlike the Chinese Tejaprabha Buddha painting, the concept of YiSipPalSoo (28 constellation of eastern philosophy) in this painting clearly reflects Korean CheonMoonDo's approach to constellation which can be applied to its uniqueness of the constellation worships. The fact that the Big Dipper and ChilWonSungKoon (Buddha of the Root Destiny Stars of the Northern and central Dipper) are simultaneously drawn can also be interpreted as the increase in importance of the constellation worship at the time as well.