• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.432-440
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• 2015

We investigate BER performance according to the order of spatial and frequency diversity combining in uplink SC-FDMA of SIMO systems. It is found that frequency diversity combining (FDC) after spatial diversity combining (SDC) is better than the reverse order combing in all SNR (Signal to Noise Ratio) range. Also, it is shown that FDC after SDC requires less computational complexity than the reverse order combining.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.9
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• pp.535-547
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• 2014

We investigate BER (Bit Error Ratio) performance according to the gain of spatial and frequency diversities in uplink SC-FDMA of SIMO (Single Input Multiple Output) systems. The main results of the analysis in this paper are as follows. First, we prove that performance of integrated system for considering spatial and frequency diversity combining in parallel is equivalent with the performance of sequential system for performing diversity combining in sequence. By signal modeling, it is demonstrated that the performances of both systems are the same when the frequency diversity combining technique of the sequential system is equal to diversity combining technique of the integrated system, and spatial diversity combining technique of the sequential system is performed as MRC in advance of frequency diversity combining. Secondly, it is found that effect on the BER performance is different according to the gain of spatial and frequency diversities, respectively. The frequency diversity gain increases by increasing the number of subcarrier. It might affect the performance improvement of high SNR(Signal to Noise Ratio) while it maintains gap between performances of ZF(Zero Forcing) and MMSE(Minimum Mean Square Error) in frequency diversity combining schemes. Also, spatial diversity gain increases as the number of receiving antennas increases. It means that it can reduce performance gap between ZF and MMSE in frequency diversity combining schemes by increasing the number of receiving antennas. In addition, it might affect the performance improvement of the whole SNR. Finally, through the analysis of performance according to the spatial diversity gain, the performance of ZF in frequency diversity combining is equal to the MMSE if the number of receiving antennas is 6 or more.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.81-88
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• 2012

Space diversity and space multiplexing gain can be achieved with MIMO system. This paper proposes spatial coding method to MIMO system using data information and antenna selection technique. This technique provides coding gain as well as space diversity gain. For MIMO system with BPSK modulation, BER performance is analyzed and space diversity gains are compared through simulation in terms of data maldistribution degree.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.766-776
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• 1999

In this paper to evaluate the performance of the polarization diversity and the space diversity in the indoor environment, we used 3D Ray-tracing simulation. This model is capable of predicting small scale fading characteristics of the channel for evaluating the performances of both the polarization and the space diversity scheme. The measurement and simulation results show that the polarization diversity and the space diversity are expected to be efficiently used for the indoor environments. Moreover, the results show that the proposed polarization diversity technique using directional dual polarization microstrip array antennas has more diversity gain than the conventional polarization and space diversity using dipole antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.578-588
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• 1998

In this paper, we analyzed the propagation characteristics of polarization diversity in the view of diversity gain, cross correlation coefficient and average received signal strength, and compared it with those of space diversity. From the results, we could confirm that in the care of line of sight(LOS), space diversity gain is bigger than polarization diversity gain by 2 dB and the diversity gain of mobile transmitting with 90 degree is bigger than that of mobile transmitting with 45 degree by 1 dB. However, in the area of non-line of sight(NLOS), the diversity gains were all most the same in two diversity schemes and in specular cases, polarization diversity showed better performances. Also it was verified that under the NLOS conditions, diversity gain of mobile transmitting with 45 degree was at least 1 dB bigger than that of mobile transmitting with 90 degree.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.369-377
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• 1998

In this paper, we performed the comparisons between polarization diversity using dual polarization antennal which has $\pm45^{\circ}$slanted linear polarization characteristics and conventional space diversity in rural and residential areas. The analysis was done by evaluating the diversity gain improvement and cross correlation coefficients between two received signals through each diversity branch. From the results, we could confirmed that space diversity has bigger diversity gain than polarization diversity by 1~2 dB, and there is a little difference of $\pm0.1$ in cross correlation coefficients by analyzing CDF under portable mobile phone environments.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.35-38
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• 2009

본 논문에서는 신호 공간 다이버시티 (Signal Space Diversity) 기법이 적용된 시스템에서 최대비 합성 (Maximal Ratio Combining) 수신시 성능 이득에 대해서 분석하였다. 먼저 심볼 오류율(Symbol Error Rate)을 수학적으로 유도하였다. 유도된 공식으로부터 상한(Upper Bound) 분석을 통해 공간 신호 다이버시티 기법이 결합될 경우 기존 대비 2배, 즉 '$2{\times}$수신안테나수' 만큼의 다이버시티 이득을 가짐을 증명하였다. 그리고 모의실험 결과와 유도된 공식 결과 값이 서로 일치함을 보여 정확성을 입증하였으며, 유도된 공식을 기반으로 신호 대 잡음비(SNR; Signal-to-Noise Ratio), 수신 안테나 개수 등 주어진 시스템 변수에 따른 최적 회전 각도를 정확히 도출할 수 있음을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.240-247
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• 2004

In order to transmit data at high speed in the wireless environment, OFDM is selected as the transmission method of various high-speed wireless communication system since it has the advantage to deal easily the serious selective frequency fading channel by the multiple path. We evaluate STBC-OFDM and linear STBC-OFDM combining with a class of recently proposed linear scalable space-time block codes and OFDM in MIMO channel environments, and demonstrate the performance for spatial multiplexing and diversity gain. The codes are able to use jointly transmit diversity in combination with spatial multiplexing, and achieve spatial and temporal diversity. Frequency diversity of frequency selective channels can be utilized by combining the linear STBC and OFDM. Simulation results are shown to demonstrate the better performance of proposed approach in comparison with STBC-OFDM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1040-1046
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• 2004

The BLAST-OFDM system is an efficient method for high data rate multimedia transmission in futurewireless communication system. In this paper, a linear preceding mechanism and an efficient antenna-subcarrier assignment algorithm are proposed for the conventional BLAST-OFDM system, in order to utilize the full spatial diversity and the interleaved frequency diversity. By computer simulation, the proposed system has proved to achieve 4-5㏈ gain over the conventional BLAST-OFDM system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.607-617
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• 1999

In this paper, we fabricated dual polarization microstrip array antenna to analyze the performance of polarization diversity of each antennas beamwidth and recommend suitable polarizations diversity antenna under indoor environments. The proposed antennas which have directional beam patterns are small, light and thin. Also they are $1\times4$ array and $4\times4$ array antenna with $70^{\circ}$, $20^{\circ}$ beamwidth, respectively. The center frequency is 1890 MHz, IMT-2000's frequency. We also measured the antennas characteristics of each beamwidth in various waveguide structured corridor and compared then with the case of space diversity using the dipole antenna. The measurement shows that the polarization diversity using directional dual polarization microstrip array antennas has more 1~7 dB diversity gain than the space diversity using the dipole antenna. Therefore, the proposed antennas are expected to be efficiently used for the design of optimal directional beam pattern antenna and diversity system for indoor environments.