• Journal of information and communication convergence engineering
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• v.4 no.3
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• pp.97-100
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• 2006

In this paper, the transmission service for medical image is proposed via IEEE 802.15.4a on WPAN environment. Also, transmission and receiving performance of medical image using TH UWB-IR system is evaluated on indoor multi-path fading environment. On the results, the proposed scheme can solve the problem of interference from the medical equipment in same frequency band, and minimize the loss due to the indoor multi-path fading environment. Therefore, the transmission with low power usage is possible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4C
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• pp.207-214
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• 2005

In the indoor wireless communication, it is considered the indoor wireless system architecture of single input multiple output (SIMO) that used with multiple antenna in order to cope with the indoor fading characteristic due to severe angler spread. We propose the mean steering vector technique as a method to enhance the system Performance, implement the test bed system composed of a PC and the algorithms of the wireless system, and analysis the performance of those algorithms. In addition, the overall operation scenario, overall architecture, and the execution time of the algorithms, of the test bed for the indoor wireless system are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.114-124
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• 2002

In this paper, we proposed the image-based 3D ray tracing indoor propagation model using a patch scattering model for fading analysis of indoor propagation environments. An image-based 3D ray tracing technique is mainly used, which allows the rapid generation of the complex channel impulse response for any given location and polarization of transmitter and receiver. Due to the site specific nature of indoor environment, we took into account the location and the electrical properties of individual walls and objects such as windows, doors and plaster board in our propagation model. Besides, the 3D radiation beam-patterns and polarizations of arbitrary antennas were considered, and using patch scattering model we can consider the change of the polarization due to the scattering from the various indoor objects, like desks, chairs and etc. the are almost impossible to be modeled with the basic image-based ray tracing method. The model will predict the impulse response, the rms delay spread, the fading characteristics of the channel and performances of the polarization diversity schemes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1115-1121
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• 2001

In this paper, we analyzed the performance of GFSK system that presence fading effect in indoor radio communication environments and impulsive electromagnetic noise from electronic equipments then we applied the Truncated Type- II Hybrid ARQ scheme to make satisfied in data transmission service. As a result, the system was influenced by fading and impulsive electromagnetic noise. Especially, the system was much degraded by high occurrence frequency and amplitude of impulsive electromagnetic noise than fading which has direct frequency. By adopting the Truncated Type-II hybrid ARQ technique we can also obtained the performance improvement in the low signal power(20 dB) arid over 24 dB in strong impulsive electromagnetic noise environment which is occurred error floor and terribly influenced by the system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.245-253
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• 2010

In this paper, we derive the performance analysis of the coded cooperation over a Rician fading channel. A new scheme called coded cooperation was suggested by using user cooperation and channel codes simultaneously. In previous works, it was verified that the coded cooperation schemes have better performance than other relay schemes in a Rayleigh fading channel. However, the high speed short range indoor wireless communication system has recently attracted research attention and its channel with very high carrier frequency(60GHz) can be typically modeled as a Rician fading channel. We derive analytical outage probabilities and bit error probabilities of the coded cooperation over the Rician fading channel and prove it to have full diversity order.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.41-48
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• 2004

In this paper, we analyzed channel performance of PPM modulated UWB communication system in indoor radio fading environment that consider amplitude characteristic of channel. Fading channel considered various channel environments by fading index m utilizing Nakagami-m distribution model with data through an UBW radio signal experiment that announced in existing. Also, we improved performance of system that it is decreased in fading environment employing convolution encoding techniques.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.4
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• pp.11-20
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• 1994

The error rate equation of DS-CDMA/DQPSK skgnal adopting ARQ scheme has been derived in indoor radio channel which is characterized by AWGN, multi-user interference (MUI) and Rician fading, Using the derived equation the error performance has been evaluated and shown in figures as a function of direct to diffuse signal power ratio(KS1rT), the number of active users (K), PN code sequence length (N), the number of parity bit of linear code (b), forward channel BER, and ES1bT/NS1OT. From the results it is known that in severe fading environments (KS1rT=6) the performance of DS-CDMA/DQPSK system is not reliable so it is needed to adopt techniques for improvement. When an ARQ scheme is adopted, as a method for improving error performance, the performance improves compared with that of non-ARQ scheme and the degree of improvement is proportional to the number of parity bits of linear code. As increasing the number of parity bits, system performance is improved vut system throughput efficiency must be considered. In severe fading channel Hybrid ARQ scheme is more effective than ARQ scheme. As a result, ARQ scheme is appropriate for the high-reliability data communication systems over the radio channel in which the real time processing is not required.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1027-1035
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• 2000

In this paper, we have proposed the optimum technique for wireless ATM (WATM) error control in indoor environment. As the optimum technique, the conventional concatenated FEC only is regarded as the efficient error control method for time-critical ATM traffic in AWGN, and the pilot symbol-added fading compensation with the concatenated FEC is required to optimize the WATM performance in fading environment. Also, the truncated Type- H hybrid ARQ technique will be developed for quality-critical ATM traffic in order to improve its throughput. Therefore, this paper presents the optimization of WATM performance in indoor environment by means of evaluating above techniques using theoretical analysis and simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1473-1479
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• 2000

This paper presents the performance evaluation of an adaptive QAM scheme under flat and frequency selective fading channels for indoor wireless communication systems. The QAM modulation is combined with differential encoding and the demodulation process is carried out noncoherently. The adaptation is performed by varying the modulation level of QAM, depending upon received signal strength. The adaptation mechanism allows a 2- or 3-bit increase or decrease at a time, if the channel condition is considered to be significantly good or bad. Simulation results show that the average number of bits per symbol (ABPS) for each symbol block transmitted over a flat fading channel is higher than 5.0 and the BER performance is better than 10^-4 for a SNR value higher than 30 dB. For frequency selective fading channels, an oversampling technique in the receiver was employed. The BER performance obtained for frequency selective fading channels is better than 10^-4 with a SNR value of 40 dB and ABPS is found to be approximately 5.5. Therefore, this scheme is very useful in that it provides both very high bandwidth efficiency and acceptable performance with moderate SNR values over flat and frequency selective fading channels. In addition, this scheme provides reduced receiver complexity by way of noncoherent detection.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.765-768
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• 2000

In this paper, we analyze the channel estimation method by using Reference symbols for burst OFDM transmission systems. We set some parameters (the number of Reference symbols, the pilot spacing in Reference symbols, the update constant of equalizer coefficients) to evaluate their performance in the fixed multipath fading channel as like indoor environment.