• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.820-825
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• 2008

A method to improve isolation characteristics of internal MIMO antenna systems for wireless portable devices operating in the $2.3{\sim}2.4$ GHz band is presented. The proposed system incorporates multiple pairs of L-slots between the two antennas in the ground plane, which operate like a band-stop filter, suppressing mutual coupling between the antennas and resulting in improved isolation. A MIMO antenna system with 6 pairs of L-slots shows reflection loss of -26.4 dB and isolation of -37.5 dB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.50-56
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• 2014

This paper describes the design, fabrication, and measurement of a 4-port femtocell MIMO antenna for LTE 700MHz(Band12, 13, 14, 17, 28, 44) applications. Based on microstrip patch antenna, an impedance matching is achieved by short pin. In order to obtain sufficient bandwidth and isolation between antenna elements in a limited dimension, a cross decoupler is used. With a Voltage Standing Wave Ratio (VSWR)${\leq}2$, the measured result of the fabricated antenna provides 105MHz(0.698~0.803MHZ) bandwidth and shows the gain with 1.97dBi and isolation above 13dB. As one of the key parameters for MIMO performance evaluation, correlation coefficient of MIMO is achieved within 0.2.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.3
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• pp.22-30
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• 2010

This paper proposes a combination system of Adaptive Modulation and Coding (AMC) and Multiple Input Multiple Output (MIMO), which improves the throughput and has a better reliability. In addition, the system includes Precoding, Antenna Subset Selection and MIMO Mode Selection scheme. Finally, we make a performance analysis of the proposed system. The principal environmental parameters for the simulation experiment consist of a frequency non-selective rayleigh fading channel and a Spreading Factor (SF) of 16. Other parameters may be included in order to fulfill the requirements of the HSDP A Standard. The proposed system has a higher throughput and more reliability than the conventional system, which does not include MIMO Mode Selection scheme, Precoding or Antenna Subset Selection. According to the simulation results, the proposed system reaches the maximum throughput at 8dB, presentlng an improvement of 6dB and twice higher throughput, respect to the conventional system. Specifically, at the point of -6dB, the conventional system reaches 2.5Mbps, while the proposed system reaches 6.4Mbps at the same SNR. Also, at the point of 2dB, each system reaches 7.5Mbps (conventional system) and 15.3Mbps (proposed system), with near twice the difference. According to the results exposed above, we can conclude that the system proposed in this paper has, as the greatest contribution, the improvement of the throughput, especially, the average throughput.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1643-1648
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• 2005

MIMO system takes advantage of the spatial diversity obtained by spatially separated antennas for high- performance and high-capacity broadband wireless access. In this paper, we propose Carrier Interferometry coded MIMO-OFDM system (MIMO-CI/OFDM) which provides frequency and spatial diversity. One combined diversity gains featly improve the performance of OFDM systems. To perform a performance analysis, we have used SPW platform that provides an easy tool to analyze the performance. The results show that the performance of MIMO-CI/OFDM shows an approximately 4dB gain over the MIMO-OFDM even in highly frequency selective fading channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.944-949
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• 2015

This study proposed a patch antenna with a MIMO structure which is applicable for wireless communication equipment by combining a single patch antenna with a multi port. The proposed MIMO patch antenna was designed through the TRF-45 substrate with a relative permittivity of 4.5, loss tangent equal to 0.0035 and dielectric high of 1.6 mm, and the center frequency of the antenna was 2.45 GHz in the ISM (Industrial Scientific and Medical) band. The proposed MIMO patch antenna had a 500 MHz bandwidth from 2.16 ~ 2.66 GHz and 24.1% fractional bandwidth. The return loss and VSWR were -62.05 dB, 1.01 at the ISM bandwidth of 2.45 GHz. The Wibro band of 2.3 GHz was -17.43 dB, 1.33, the WiFi band of 2.4 GHz was -31.89 dB, 1.05, and the WiMax band of 2.5 GHz was -36.47 dB, 1.03. The radiation patterns included in the bandwidth were directional, and the WiBro band of 2.3 GHzhad a gain of 4.22 dBi, the WiFi band of 2.4 GHz had a gain of 4.12 dBi, the ISM band of 2.45 GHz had a gain of 4.06dBi, and the WiMax band of 2.5 GHz had a gain of 3.9 6dBi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.983-990
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• 2010

In this paper, we designed and implemented the MIMO antenna for LTE(Long Term Evolution), supposed to be a next generation communications network, DCS1800, DCS1900 and WCDMA. Using conventional monopole antenna with MD material results in good characteristics, miniaturization for LTE band and as well as broadbanding for DCS, WCDMA band. The performance of the proposed MIMO antenna shows VSWR < 2, under -10 dB of isolation and the gain is -1.66 ~ 1.33 dBi for LTE(Long Term Evolution), DCS1800, DCS1900 and WCDMA, which has omnidirectional radiation pattern.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4759-4780
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• 2017

Full Dimension multiple input multiple output (FD-MIMO) architecture employs a planar array design at the Base Station (BS) to provide high order multi-user MIMO (MU-MIMO) via simultaneous data transmission to large number of users. With FD-MIMO, the BS can also adjust the beam direction in both elevation and azimuth direction to concentrate the energy on the user of interests while minimizing the interference leakage to co-scheduled users in the same cell or users in the neighboring cells. In a typical highly populated macrocell environment, modelling the elevation angular characteristics of three-dimensional (3D) channel is critical to understanding the performance limits of the FD-MIMO system. In this paper, we study the throughput performance of FD-MIMO system with varying elevation angular spread and inter-element spacing using a 3D spatial channel model. Our results show that for a typical urban scenario, horizontal beamforming with correlated antenna spacing achieves optimal performance but by restricting the spread of elevation angles of departure, elevation beamforming achieves high array gain with wide inter-element spacing. We also realize significant gains due to spatial array processing via modelling the elevation domain and varying the inter-element spacing for both the transmitter and receiver.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1032-1037
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• 2016

In this paper, the method of isolation enhancement for the mobile phone MIMO antenna of LTE class 40(2300~2400MHz) was studied. Design of MIMO antenna was based on the hybrid antenna that operates both a monopole and an IFA(Inverted F Antenna). A structure for the isolation enhancement which controls induced electric field on the ground plane is located between MIMO antenna, and was not connected with the ground but apart 0.3mm. A MIMO antenna that operates on class 3~40(1710~2400MHz) of LTE service bands and a structure for the isolation enhancement at the class 10 band were designed. VSWR measurement of implemented antenna on the FR4 board showed within 3:1 at entire design bands, and isolation between antennas at the class 40 band was less than -30dB. Isolation was enhanced more than 20dB by the studied structure. ECC(Envelope Correlation Coefficient) for MIMO performance was under 0.1, and antenna average gain and efficiency measured in the anechoic chamber were -4.28~-1.40dBi and 37.32~72.36% respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.79-86
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• 2008

This paper presents to improve of isolation characteristics between personal communication service(PCS) antenna In mobile terminal and 2-channel multi input multi output(MIMO) antenna in the wireless broadband Internet(WiBro) band. In order to improve the isolation between each channel antenna, the proposed PCS antenna with an air space of 3 mm height is located on the projected ground plane($25{\times}12mm$) which is very small space$(0.19{\lambda})$ between the 2-channel WiBro-MIMO antenna. The proposed PCS antenna structure is a modified planar inverted F antenna (PIFA) of spiral type with shorting strip line(6${\times}$4 mm). The calculated Isolation values between the proposed PIFA with 3-dimensional structure and the MIMO antenna at Wibro band are about -20dB below and agree well with the measurement. Measured return loss, bandwidth, and gain o# the proposed antenna are -20dB at 1.8GHz, 110MHz(1.76${\sim}$1.87 GHz) band at -10dB below, and 0.05dBi, respectively, Moreover, we confirm that the proposed PCS antenna has no influence on performance and characteristics of the conversional 2-channel WiBro-MIMO antenna.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.2
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• pp.67-76
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• 2013

Under an imperfect channel estimation, a Device-to-Device (D2D) communication framework based on MIMO relay technology is presented. The model consists of a D2D pair equipped with M antennas and a relay equipped with N antennas as well as a cellular user equipped with M antennas. The outage probability under different relaying protocols (i.e. AF and DF protocol) with and without considering a direct link was derived. The actual and theoretical outage probability of the five links under different antenna numbers was emulated. The number of user antennas and channel estimation error was analyzed carefully to determine their impact on the outage probability of a system. The simulation verified the theory analyses and the results showed that MIMO relaying improves the D2D communication system performance.