• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.198-203
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• 2008

In this paper, we consider the diffuse type of indoor wireless optical communication (WOC) system. To find the channel characteristics of indoor wireless infrared communication system, we investigate the simulation process to get the impulse response of diffuse type and analyze the scenario of the indoor structure which we have built. The simulation results of the impulse response include power ratio and time delay due to bounce times. We get and discuss the receiving power distribution according to six configurations which have different transmitter and receiver positions and reflection coefficients of the indoor structure assumed. The results of this paper are useful to design the indoor wireless optical communication systems.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.64-69
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• 2013

Recently, users who are interested in the service at indoor spaces is increasing. An indoor positioning system can minimize a range of positioning error using a variety of wireless communication infrastructure. Also, the system improves an indoor positioning accuracy by combining a mobile communication network. However, flexible positioning technologies regardless of an environment are insufficient. Therefore, this is time for a systematic study on an indoor positioning system business model. This paper classify differences between an indoor positioning system technology and outdoor positioning system technology. And we research a construction and application of the indoor positioning system that is adapted a wireless communication system (Wi-Fi, Bluetooth, RFID, UWE, Fingerprint, etc.) in domestic and foreign. We present a successful model of indoor positioning system and the development for future systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.285-291
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• 2010

In this paper, we demonstrate that indoor wireless optical communication is possible with an LED and a solar cell. A lighting LED is used for lighting and signal transmission. A solar cell is used for collecting light energy and signal detection. This scheme is very useful because transmission is possible without any additional communication systems. In experiments, wireless optical communication was carried out at a data rate of 9.6 kbps using a lighting LED and a solar cell.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.3145-3162
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• 2023

As an important technology of the internetwork, wireless sensor network technique plays an important role in indoor localization. Non-line-of-sight (NLOS) problem has a large effect on indoor location accuracy. A location algorithm based on improved particle filter and directional probabilistic data association (IPF-DPDA) for WSN is proposed to solve NLOS issue in this paper. Firstly, the improved particle filter is proposed to reduce error of measuring distance. Then the hypothesis test is used to detect whether measurements are in LOS situations or NLOS situations for N different groups. When there are measurements in the validation gate, the corresponding association probabilities are applied to weight retained position estimate to gain final location estimation. We have improved the traditional data association and added directional information on the original basis. If the validation gate has no measured value, we make use of the Kalman prediction value to renew. Finally, simulation and experimental results show that compared with existing methods, the IPF-DPDA performance better.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.7-11
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• 2008

Future electric lights will be composed of white LEDs (Light Emitting Diodes). Indoor wireless optical communication systems utilizing white LED lights have been studying about it. Generally, plural lights are installed in room. Therefore, their optical path difference must be considered. In this paper, the influence of an optical path difference has been investigated and two approaches against this problem are introduced. One uses OOK-RZ (On-Off Keying, Return-to-Zero) coding and the other uses optical OFDM (Orthogonal Frequency Division Multiplexing). From the results of computer simulations, we have found that these approaches are feasible for the wireless optical communication systems utilizing white LED lights.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.157-165
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• 2003

The purpose of this paper is to analyze the performance requirements of wireless systems on ultra wide band, which is set by FCC(Federal Communications Commission). Normally the calculation of performance requirements is used in the standard form of each communication systems, but there is no standard in the wireless systems on Ultra WideBand. Therefore, I derive each system parameters through the analysis of new system performance on the basis of the method of Indoor Communication Systems. Additionally, I compare the conditions that are given by FCC with resolution of the performance by domestic law.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.852-857
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• 2010

In this paper, we proposed and demonstrated an indoor visible-light communication system using an array of light-emitting diodes (LEDs). The main idea is based on that the LEDs can be used not only for lighting but also for free-space optical communications. Because LEDs offer advantageous properties such as high brightness, reliability, lower power consumption and long lifetime, the indoor visible-light communication systems are going to provide high quality of service by the high radiation power of the LED lighting. Prototype of simplex channel for audio and the full-duplex channel for text message were developed. Results indicates the viability of creating inexpensive free-space optical communication transceivers that might be embedded in commercial light products to supports indoor wireless networking.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1251-1260
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• 2008

Diffuse wireless optical communication offers more robust optical links in terms of coverage and shadowing than line-of-sight links. However, traditional diffuse wireless infrared (IR) transceiver systems are more susceptible to multi-path distortion and great power decrease, which results in limiting high-speed performance. Multi-beam is an effective technique to compensate for multi-path distortion in a wireless infrared environment. The goal of this paper is to analyze the transmission characteristics by replacing traditional diffuse system (TDS) which contains single wide angle transmitter and single element receiver by system consisting of three-beam transmitter and non-imaging receiver (TNS) attached with compound parabolic concentrator (CPC). In the simulation, we use the recursive model developed by Barry and Kahn and build the scenario based on 10 different cases which have been listed in Table 1. Moreover, we also check the reliability of the TNS diffuse link channel by BER test on the basis of different receiver positions and room sizes. The simulation results not only show the basic transmission characteristics of TNS diffuse link, but also are references to design more efficient and reliable indoor infrared transmission systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.771-779
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• 2002

A new signal model suitable for indoor wireless environments with large angle spread is proposed to improve the performance of indoor wireless communication systems. Antenna array techniques adopted for this model are discussed. It is based on the far-field signal assumption. The optimal beamforming weight vector is obtained by applying the antenna algorithm based on the maximum signal to interference noise ratio criterion to the model. The proposed model is verified using a mathematical analysis and computer simulations.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.1-6
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• 2014

In many medical image devices, dc noise often prevents normal diagnosis. In wireless capsule endoscopy systems, multipath fading through indoor wireless links induces inter-symbol interference (ISI) and indoor electric devices generate impulsive noise in the received signal. Moreover, dc noise, ISI, and impulsive noise are also found in optical fiber communication that can be used in remote medical diagnosis. In this paper, a blind signal processing method based on the biased probability density functions of constant modulus error that is robust to those problems that can cause error propagation in decision feedback (DF) methods is presented. Based on this property of robustness to error propagation, a DF version of the method is proposed. In the simulation for the impulse response of optical fiber channels having slowly varying dc noise and impulsive noise, the proposed DF method yields a performance enhancement of approximately 10 dB in mean squared error over its linear counterpart.