• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2562-2570
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• 1997

This paper deals with the design and performance of the adaptive equalizer using high order statistics in order to improve the transmission characteristics of multipath fading channel. The multipath propagational phenomenon occurred in digital radio transmission causes the distortion and ISI of receiving signal. These are main reasons to increase the bit error rate and degrade the performance of receivers. In this paper, the adaptive equalization algorithm using high order statistics of received signal is used instead of CMA algorithm, Bussgang and Godard which are known widely. The performance of this algorithm (residualisi, recovered constellation, calculation) is presented varing SNR. As the result of the computer simulation, equalizer algorithm using high order statistics is better than CMA in the range of low SNR, $10{\sim}20dB$. Therefore, considering the actual communication systems which use the range of $14{\sim}20$ SNR, the adaptive equalizer using high order statistics can be used in the real multipath fading environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2233-2240
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• 2007

This paper presents the measured path loss exponents and standard deviations using measured data at 60GHz to analyze the propagation characteristics of millimeter wave bands having great demand for picocellular communications. In addition the angle of arrival(AOA) were measured to analyze the arrival direction of muitipath waves affecting the received signal strength. As results of analysis, the pathloss exponents in each environment are found to be lower than 2 for free space pathloss exponent. They were determined with the qualities of bottom materials affecting signal strength. The angles of arrival by multipath waves were different with the circumference structures between transmitter and receiver. That is, the multipath waves excluding direct and ground reflected wave were difficult to find in wide space such a gymnasium and playground, however the wall multipath waves were found to arrive at receiver in the corridor. The multipath waves at 60GHz can be known to hardly affect to the received signal strength because of weak signals compared with direct wave.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.127-127
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• 2004

• Journal of IKEEE
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• v.14 no.1
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• pp.25-32
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• 2010

In this paper, we analyze the location accuracy of real-time locating systems (RTLS) in multipath environments, where the RTLS complies with an ISO/IEC 24730-2 international standard. RTLS readers should have an ability not only to recover the transmitted signal but also provide arrival timing information from the received signal. In the multipath environments, in general, the transmitted signal goes through both direct and indirect paths, and then it becomes some distorted form of the transmitted signal. Such multipath components have a critical effect on deciding the first arrival timing of the received signal. To analyze the location error of the RTLS in the multipath environments, we assume two multipath components without considering an additive white Gaussian noise. Through the simulation and real test results, we confirm that the location error does not occur when the time difference between two paths is more than 1.125Tc, but the location error of about 2.4m happens in case of less than 0.5Tc. In particular, we see that the resolvability of two different paths depends largely on the phase difference for the time difference of less than 1Tc.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.1
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• pp.83-89
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• 2000

Antenna arrays at base-stations can be used to transmit and receive information selectively in space by reducing the interference effects. In this paper, a new model of locally scattered signals in the vicinity of mobiles is proposed, and under this model the weights of the beamformer are obtained. Computer simulation results demonstrate that the proposed scheme shows an excellent performance and works well even in the urban environment where there exist many multipath propagations with wide angular spread.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.689-692
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• 2008

WAVE based on OFDM is made for vehicle to vehicle wireless communication. Its performance is decreased by continual timing delay in multipath fading channels after starting initial timing synchronization. In this paper, the tracking algorithm that synchronizes symbol timing is proposed to continually compensate additional timing delay. Computer simulation of the proposed algorithm is performed in the worst communication environment that applies to maximum timing delay. Computer simulation shows that the proposed algorithm can improve the system performance in various channel conditions.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.11
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• pp.977-983
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• 2016

This paper proposes a novel code-tracking scheme to track the fine code synchronization for BOC (pn,n)-modulated global navigation satellite system signals in a repeat-back jamming environment. The correlation function of BOC (pn,n)-modulated signals has several peaks. The correlation function in the advanced offset region remains almost unchanged due to the repeat-back signals being received later than a line-of-sight signal in the same multipath signal receiving case. Additionally, the combined pseudo-random noise signal can be treated as repeat-back jamming signals, like multipath signals. In this paper, we propose a novel code-tracking scheme utilizing the advantages of using a combined pseudo-random noise signal in the advanced offset region and verify its performance through simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.884-892
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• 1996

An adaptive blind equalizer is used to combat the distortions caused by a nonideal channel without resorting to a training sequence, given the received signal and statistical information of the transmitted signal. Incidentally, a multipath channel may result in a fade which produces intersymbol interference in the received signal. Therefore, a new type of algorithm which can compenste the effects of this fade is required in the multipath channel environment. In this paper, a modified form of adaptive blind equalization algorithm using stop-and-go algorithm for multichannel system is proposed. It is demonstrated via computer simulations that the performance of the proposed multichannel stop-and-go algorithm is much better than that of the conventional multichannel algorithms.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.2
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• pp.95-102
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• 2013

In this paper, we have studied the performance of the AOA (Angle of Arrival) in multi-antenna systems for LBS (Location Based Services) and we also analyzed the performance of the AOA in SISO (Single Input Single Output) in multipath environments and their differences. The adequacy of AOA positioning in new communication environments was determined. Currently used positioning methods in 3G communication environment has been developed based on SISO. However, the accuracy of SISO-based TOA (Time of Arrival), TDOA (Time Difference of Arrival), AOA positioning techniques degraded in multipath environments. The communication system will be changed and developed. According to enhanced positioning techniques are required. Using antenna characteristics and the phase difference between antennas of LTE-Advanced standard's key technique MIMO system AOA positioning, and SISO based AOA positioning performance were analyzed. We found that AOA technique potential for use based on Multiple antenna systems by computer simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.106-112
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• 1993

A new model for the construction of a sonar map in a specular environment has been developed ad implemented. In a real world where most of the object surfaces are specular ones, a sonar sensor suffers from a multipath effect which results in a wrong interpretation of an objects's location. To reduce this effect and hence to construct a reliable map of a robot's surroundings, a probabilistic approach based on Bayesian reasoning is adopted to both evaluation of object orientations and estimation of an occupancy probability of a cell by an object. The usefulness of this approach is illustrated with the results produced by our mobile robot equipped with ultrasonic sensors.