• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1521-1528
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• 2000

In this paper we analyze the performance of a DS/CDMA system in LEO mobile satellite channels. The channel uses the Extended Suzuki model which is the product of a Rician distribution having a LOS component and a lognormal distribution due to shadowing. We assume that the signal transmitted from the satellite to the mobile undergoes the same fading for the whole coverage of signal's beam. The average bit error probabilities of double coverage system is calculated in this paper. The interference resulting from the reference satellite is calculated for mobile located in the middle of the double coverage region whereas the additive interference from next-satellite is included for mobile located in the edge of the double coverage region. The performance of the mobile's receiving signal is dependent on shadowing and the interference of the next-satellite. We can obtain an obtain an improved average bit error probability by using dual diversity over the conventional correlated receiver for similar shadowing conditions in the coverage area of the satellite channel.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1303-1311
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• 2008

In this paper, we analyzed the error rate performance of convolution coded 16 QAM signal in impulsive noise Environments. We used convolution code and selective combining diversity for performance improvement. We analyzed the error rate performance of 16 QAM signal in impulsive noise environments compared with gaussian noise environments. As a result of analysis, there is a BER segment where the efficiency of system does not improve until which limit to raise a signal power potential from impulsive noise environment. when the signal power potential which goes over this limit is supplied, BER efficiency improve much more.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.268-277
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• 2001

In this paper, the system performance with the convolution code using a Viterbi decoding and the one tap LMS equalizer applied to the OFDM system, which is suitable for IEEE 802.1la wireless LAN in indoor wireless channel, is analyzed through computer simulation. Indoor wireless channel is modeled as Rician fading channel, and QPSK and 16QAM scheme are used for subchannel modulation. In Rician fading channel with the power ratio of the direct path signal to the scattered signals, K=5 dB, BER of $10^{-4}$ is satisfied if the SNRs of the QPSK/OFDM and the 16QAM/OFDM are 8.6 dB and 19.2 dB in hard decision and 5.3 dB and 9.8 dB in soft decision, respectively. Compared with convolution code scheme, it is observed that 16QAM/OFDM system with the one tap LMS equalizer has the performance improvement of 8.6 dB and 2 dB in hard decision and soft decision, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.2
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• pp.151-160
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• 1997

In this paper, we have carried out the DS/CDMA with a suppressed pilot channel, which is used in receiving coherently with Rake diversity and in synchronizing the chip timing, in the mobile satellite communication. Also, we have investigated the envelope variation of a shadowed Rician fading simulator, and analyzed the error performences of DS/CDMA in the mobile satellite communication. The results showed that the error performance in the Heavy shadowing environment might be degraded more than in the Rayleigh fading environment since the fading envelopes in the former environment are varied randomly compared with those in the latter environment. And the performence of DS/CDMA system could be improved about 10 dB compared with that of narrowband QPSK system. In conclusion, DS/CDMA with a suppressed pilot channel had the best performance in the case of the suppressed pilot channel to transmission power ratio $\beta$=-8 dB, the number of complex delay profiles $N_{profile}$=32, and using these values, the error performance of DS/CDMA in Light shadowing environment was identical to the ideal QPSK error performance.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.41-47
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• 2005

In this paper, the performances of various channel estimation schemes for DVB-H system are investigated. The linear interpolation, the second order interpolation, the cubic spline interpolation, and the time-domain interpolation, which are used in frequency domain, are chosen as the channel estimation schemes. We derived the performances of Mean Square Error (MSE), Bit Error Rate (BER), and the complexity of calculation in Rayleigh and Rician fading channel through computer simulations. From the simulation results, the cubic spline interpolation shows the best performance under high $E_b/N_0$ environments.

• ETRI Journal
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• v.34 no.6
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• pp.858-868
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• 2012

In this paper, stochastic models for the cross-correlation of multiple channels are established based on measurement data collected using a wideband multiple-input multiple-output relay Band Exploration and Channel Sounder system at 3.7 GHz. We propose models for the cross-correlation characteristics of large-scale parameters (LSPs) between two links, that is, the base station and mobile station (MS) link and the relay station and MS link. The LSPs include shadow fading, Rician K-factor, delay spread, angle spread of arrival, and angle spread of departure. Furthermore, models are established for the cross-correlation of the small-scale fading in the impulse responses of two links. The statistics of these model parameters are investigated as functions of geometrical features of the multilink. They are extracted from a large amount of cross-correlation observations, which are obtained in three measurement sites along more than one hundred measurement routes. These models can be used together with the standard single-link channel models for the generation of correlated components, for example, path clusters, in two separate channels.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.853-864
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• 2001

In this paper, system model is based on proposed standardization by 3GPP(Asynchronous IMT-2070 system), and we have analyzed the performance of the DS-CDMA/QPSK which cancelled self-interference, so that occurs when the received signal time is delay by multipath fading. We proposed the new scheme that designed for self-interference cancellation and the system performance is calculated in Rician fading and Rayleigh fading channel. The proposed rake receiver can be achieved a gain of about 1 [dB]∼6 [dB] more than generally rake receiver, and will be a very effective method to improve the performance of IMT-2000, and these data can be available for modem design of DS-CDMA.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.22-27
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• 2014

In this paper, we analyzed performance of FFT based on pilot sensing scheme for DTV signal in fading environments. In order to detect the present and absent for advanced television system committee digital television (ATSC DTV), a pilot detection scheme based on FFT is employed. Also, these signals are applied to each fading environment. For evaluating the spectrum sensing performance, detection probability is derived. When threshold is decided, we refer to constant false alarm rate (CFAR) scheme. From simulation results, it is confirmed that the spectrum sensing performance is improved as increase of the false alarm rate. The result of this paper can be applied to implement the spectrum sensing part of cognitive radio (CR) systems.

• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.151-157
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• 2002

This paper has investigated the PER performance and the packet throughput of Bluetooth multi-piconet in the presence of impulsive noise, Rician fading, and co-channel interference. Specially, it is simulated the effect of co-channel interference in Bluetooth multi-piconet. From the simulation results, it is obtained that the co-channel interference due to multi-piconet and impulsive noise affects performance of Bluetooth multi-piconet. And, we have known that the SAW-ARQ method is very efficient to improve the performance of Bluetooth packet transmission.

• Journal of Advanced Navigation Technology
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• v.5 no.2
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• pp.158-164
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• 2001

We presented a channel model for the inter vehicle radio link including the reflection from the road surface, side road vehicle and concrete wall. Then we theoretically derived the path loss and delay profile characteristics using the Ray tracing method efficiently analyzing millimeter wave or optic wave. Finally, we shown the improvement of propagation characteristics by diversity techniques, BCH coding and convolution coding techniques. At the result, MRC diversity techniques and BCH coding can't obtained PER = $10^{-6}$ which is considered to be data service criterion. But, we knew that Packet Error Rate Characteristic can obtained PER = $10^{-6}$, which is considered to be data service criterion, when convolution coding scheme are adopted in Rician fading.