• Title/Summary/Keyword: Diversity Gain

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Analysis on the Impact of Multiple-Antenna Transmit Schemes on Multiuser Diversity

  • Lee, Myoung-Won;Mun, Cheol;Yook, Jong-Gwan
    • Journal of electromagnetic engineering and science
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    • v.6 no.4
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    • pp.222-228
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    • 2006
  • In this paper, the performance of a multiuser diversity system combined with a multi-element transmit antenna system is analyzed under the assumption of independent Rayleigh fading. A measure of system .level performance is an average channel capacity as a function of the number of users and antennas. Average channel capacity is obtained from the instantaneous signal-to-noise ratio(SNR) distribution combined by both transmit diversity(TD) at each link and multiuser diversity at system level. Numerical results show that closed-loop antenna techniques provide an additional gain with multiuser diversity system due to array gain, even though space diversity gain reduces multiuser diversity gain. On the other hand, the space-time block coding(STBC) that provides full order space diversity gain only has a destructive influence on multiuser diversity.

Analysis of BER According to Spatial and Frequency Diversity Gain in Uplink SC-FDMA with SIMO Systems (상향링크 SIMO 시스템에서 공간 및 주파수 다이버시티 이득에 따른 SC-FDMA의 BER 성능 분석)

  • Lee, Jin-Hui;Choi, Kwonhue
    • 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.

Definition of Antenna Diversity Gain in User-Distributed 3D-Random Line-of-Sight

  • Kildal, Per-Simon;Carlberg, Ulf;Carlsson, Jan
    • Journal of electromagnetic engineering and science
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    • v.13 no.2
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    • pp.86-92
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    • 2013
  • The present paper defines diversity gain for stationary users. This deals in particular with gathering the received signal statistics over possible user positions and orientations in space rather than over time, and to define a meaningful diversity gain related to the cumulative improvement of the performances of the 1% users with the worst receiving conditions. The definition is used to evaluate diversity gain for some typical small antennas in an extreme environment with only line-of-sight (LOS). The LOS environment is regarded as user-distributed 3D-random LOS caused by the statistics of an ensemble of stationary users with arbitrary orientations in the horizontal plane (2D), and with arbitrary orientations of their wireless devices in the vertical plane. Thus, an overall 3D-random distribution of user orientation is assumed.

Performance Analysis of LR-aided ZF Receiver for MIMO Systems

  • Kim, Sangchoon
    • International journal of advanced smart convergence
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    • v.7 no.3
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    • pp.37-43
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    • 2018
  • Lattice-reduction (LR) techniques have been developed for signal detection in spatial multiplexing multiple input multiple output (MIMO) systems to obtain the largest diversity gain. Thus, an LR-assisted zero-forcing (ZF) receiver can achieve the maximum diversity gain in spatial multiplexing MIMO systems. In this paper, a simplified analysis of the achievable diversity gain is presented by fitting the channel coefficients lattice-reduced by a complex Lenstra-Lenstra-$Lov{\acute{a}}z$ (LLL) algorithm into approximated Gaussian random variables. It will be shown that the maximum diversity gain corresponding to two times the number of receive antennas can be achieved by the LR-based ZF detector. In addition, the approximated bit error rate (BER) expression is also derived. Finally, the analytical BER performance is comparatively studied with the simulated results.

A Study on the Performance Evaluation of Polarization Diversity in Heavy Density Urban (고밀집 도심에서의 편파 다이버시티 성능 분석 연구)

  • Ihm, Jong-Tae;Kim, Sung-Jin;Kwon, Bum
    • 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.

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A Simple Dual-Antenna Diversity Gain Measurement System at 2.4GHz

  • Kim, Jin-Gyong;Chung, Kyung-Ho;Ho, Yo-Choul;Kim, Moon-Il
    • Journal of IKEEE
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    • v.13 no.2
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    • pp.220-223
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    • 2009
  • A simple measurement system is built to estimate the dual-antenna diversity gain at 2.4GHz easily in open lab environment. To obtain multipath fading propagation channel, the system consists of two transmission horn that placed on opposite direction and a rotating stage mechanically changing the position of test dual-antenna with time over distance greater than one wavelength. Estimated diversity is nearly same as theoretical value such that measured diversity gain of 30mm separated is about 6dB similar to theoretical value of 5.7dB and increases monotonically with the increasing separation distance as predicted by the theory. Proposed measurement system that is simple enough to fit in a small space can evaluate the performance of various dual-antennas with a reasonable accuracy with lower 5% difference between the ten sets of measured waveform distribution and theoretical Rayleigh cumulative distribution.

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Transmission Diversity Scheme Using Antenna Array of Small Cell (소형 기지국의 안테나 배열을 이용한 전송 다이버시티 기법)

  • Paik, Jong-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.3
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    • pp.301-303
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    • 2016
  • This paper proposes a method providing diversity gain using small base stations in a cell coverage in order to improve diversity gain. The small base stations and the conventional base station consist a virtual MIMO array by using the cooperative communication scheme. Also, transmission diversity scheme is applied. A mobile user can receive the signals having the improved reliability by the applied transmission diversity scheme and the cooperative communication scheme.

A Study on the Propagation Characteristics of Polarization Diversity in rural and Residential Areas (교외 및 주거 지역에서의 편파 다이버시티 전파전파 특성 연구)

  • 임종태;김성진;유봉국
    • 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.

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Improvement Transmission Reliability between Flight Type Air Node Using Concatenated Single Antenna Diversity (비행형 에어노드의 데이터 전송 신뢰성 향상을 위한 연접 단일 안테나 다이버시티 시스템)

  • Kang, Chul-Gyu;Kim, Dae-Hwan
    • Journal of Advanced Navigation Technology
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    • v.15 no.6
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    • pp.1053-1058
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    • 2011
  • In this paper, we propose a concatenated single antenna diversity system to assure the data transmission reliability between flight type air nodes which move according to their atypical orbit, then analyze its performance. The proposed system achieve a diversity gain using single antenna and a coding gain from convolutional code simultaneously. Simulation result about the bit error rate(BER) of the proposed system shows that its BER performance is about 9.5dB greater than convolutional code at $10^{-4}$ and about 14dB greater than space time block code at $10^{-3}$ which has a full diversity gain. In addition, compared with space time trellis code with diversity gain and coding gain, the proposed system shows the better 4dB at a BER of $10^{-5}$. Therefore, it is necessary that concatenated single antenna diversity should be adopted to the reliable data transmission of flight type air nodes.

A New Asymptotic Analysis of Throughput Enhancement from Selection Diversity in Multiuser Systems (다중 사용자 다이버시티로부터 얻게 되는 처리율 증가에 대한 새로운 근사적 분석)

  • Seo, Woo-Hyun;Kim, Sung-Tea;Kwak, Kyung-Chul;Hong, Dae-Sik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.11C
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    • pp.1111-1118
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    • 2007
  • This paper presents our study of throughput enhancement achieved by selection diversity in a multiuser system, called multiuser diversity (MUDiv), using a new asymptotic approach. The MUDiv gain is evaluated by deriving an asymptotic formula for the throughput enhancement from the MUDiv gain as a simple closed form introducing a Puiseux series. The formula shows that the MUDiv gain is independent of the signal-to-noise ratio (SNR). This concept can be extended to analysis applicable to scheduling algorithms, such as Max C/I and proportional fair scheduling. The MUDiv gain throughput analysis is verified using Monte-Carlo simulations.