• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.328-334
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• 2012

This paper proposes a design technique of wide-band antenna for handy phone with 700 MHz LTE(Long Term Evolution) low frequency bandwidth. The proposed antenna based on the PIFA(Planar Inverted-F type Antenna) structure was designed and considered. In order to realize the wide bandwidth, a round structure which is able to control the electric path length of current and a branch line element which can be obtain the dual resonance characteristics were introduced in this design. As a result, It was realized about 95 MHz bandwidth in spite of very small space of $30{\times}34mm$ used for FR-4 substrate with relative permitivity of 4.4 at 700 MHz band. Measurement results of return loss, bandwidth and gain radiation pattern were agreed well with their calculation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.2
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• pp.61-74
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• 2014

In recent years, development of femtocells are receiving considerable attention towards increasing the network coverage, capacity, and improvement in the quality of service for users. In 3GPP LTE-Advanced (LTE-A) system, to efficiently utilize the bandwidth, femtocell and macro cell uses the same frequency band, but this deployment poses a technical challenge of cross-tier interference to macro users. In this paper, the novel quality of service based fractional power control (QoS-FPC) scheme under the heterogeneous networks environment is proposed, which considers the users priority and QoS-requirements during the power allocation. The proposed QoS-FPC scheme has two focal points: firs, it protects the macrocell users uplink communication by limiting the cross-tier interference at eNB below a given threshold, and second, it ensures the optimization of femtocell users power allocation at each power adjustment phase. Performance gain is demonstrated with extensive system-level simulations to show that the proposed QoS-FPC scheme significantly decreases the cross-tier intereference and improves the overall users throughput.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.127-134
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• 2022

A modified folded monopole slot antenna for 3G WCDMA (1.91 ~ 2.17 GHz), 4G LTE (2.17 ~ 2.67 GHz), 3.5 GHz 5G (3.42 ~ 3.7 GHz) and Wi-Fi dual band (2.4 ~ 2.484 GHz / 5.15 ~ 5.825 GHz) was proposed for the first time. The proposed antenna is designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 35 × 60 mm². The measured impedance bandwidth of the proposed antenna is 2910 MHz(1.84 ~ 4.75 GHz) and 930 MHz(5.11 ~ 6.04 GHz), antenna gain in each frequency band is from 1.811 to 3.450 dBi. In particular, it was possible to obtain a commercially suitable omni-directional radiation pattern in all frequency bands of interest.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.77-82
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• 2019

In this paper, a 0.6~6GHz quad-ridge horn antenna which can be used for the antenna measurement of 5.8GHz WiFi system from lowest frequency band of mobile LTE (Long Term Evolution) is designed and implemented. The quad-ridge horn antenna has quadruple ridges of exponential function, a back-short and a cavity. Based on this structure, we design the cavity size, ridge gap and feed gap to have broadband characteristics. For implementation, the plates material of aluminum and copper are used for the horn and four ridges, respectively. And the insulator supports are used to maintain the gap between ridges. By measurement, antenna has the gain of 6.2~13.35dBi with the return loss of less than -6dB (under VSWR 3 : 1) in the entire design band. The results of this study can be widely used to the antenna studies on the mobile communication including low frequency band of LTE, the EMI measurement and the standard calibration measurement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.577-584
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• 2017

Long Term Evolution device-to-device (LTE D2D) is a key technology to mitigate data traffic load in a cellular system. It facilitates direct data exchange between neighboring users, which is preceded by D2D discovery. Each device advertises its presence to neighboring devices by broadcasting its discovery message. In this paper, we develop a mathematical analysis to assess the probability that discovery messages are successfully transmitted at the D2D discovery stage. We make use of stochastic geometry for modeling spatial statistics of nodes in a two dimensional space. It reflects signal to noise plus interference ratio (SINR) degradation due to resource collision and in-band emission, which leads to the discovery message reception probability being modeled as a function of the distance between the transmitter and the receiver. Numerical results verify that the newly developed analysis accurately estimates discovery message reception probabilities of nodes at the D2D discovery stage.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.75-80
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• 2021

In this paper, a dual-band Koch Snowflake antenna is proposed for wireless communication systems. Fractal geometry, CPW-feed and stepped ground planes are used to improve the impedance bandwidth. By properly introducing a hexagonal split-ring slot to radiating element, a lower frequency band is generated. The proposed structure is fabricated and tested. Experiment results exhibit dual-band of 0.73-0.98 GHZ and 1.6-3.1 GHz which makes this antenna suitable candidate for GSM900, GSM1800, UTMS2100, Wi-Fi 2400 and LTE2600 bands. In addition, a good radiation pattern, a satisfactory peak gain and a radiation efficiency, which reaches 95%, are achieved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1672-1678
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• 2022

In this paper, the relay antenna was designed in consideration of the performance of the 28GHz band 5G mobile communication relay horn antenna, such as radiation pattern and return loss. A horn array for 5G mobile communication repeater was designed by arranging the antenna elements in phase, and the performance was analyzed. Unlike conventional WCDMA (3G) and LTE (4G), in millimeter wave band communication, high path loss occurs between transmission and reception. In the design of a 5G millimeter wave horn antenna, antenna performance such as isolation and gain between antenna elements as well as gain and bandwidth of the antenna must be additionally considered. The antenna gain of the single horn antenna (1×1) and the array horn antenna (2×4) in the 28GHz band is about 10.44d Bi and 19.58dBi, respectively, and the return loss is designed to be less than -18dB. It has proven its validity and has been shown to be suitable for application to 5G mobile communication relay system.

• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.61-67
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• 2014

This paper presents a zero-IF CMOS RF receiver, which supports three channel bandwidths of 5/10/40MHz for LTE-Advanced systems. The receiver operates at IMT-band of 2,500 to 2,690MHz. The simulated noise figure of the overall receiver is 1.6 dB at 7MHz (7.5 dB at 7.5 kHz). The receiver is composed of two parts: an RF front-end and a baseband circuit. In the RF front-end, a RF input signal is amplified by a low noise amplifier and $G_m$ with configurable gain steps (41/35/29/23 dB) with optimized noise and linearity performances for a wide dynamic range. The proposed baseband circuit provides a -1 dB cutoff frequency of up to 40MHz using a proposed wideband OP-amp, which has a phase margin of $77^{\circ}$ and an unit-gain bandwidth of 2.04 GHz. The proposed zero-IF CMOS RF receiver has been implemented in $0.13-{\mu}m$ CMOS technology and consumes 116 (for high gain mode)/106 (for low gain mode) mA from a 1.2 V supply voltage. The measurement of a fabricated chip for a 10-MHz 3G LTE input signal with 16-QAM shows more than 8.3 dB of minimum signal-to-noise ratio, while receiving the input channel power from -88 to -12 dBm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.171-175
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• 2013

In this paper was The dielectric constant of 4.4 and thickness of 0.6mm FR-4 substrate were implanted including the L-Slot in microstrip patch antenna to design a microstrip patch antenna for LTE. The proposed antenna is $180{\times}180$ compact and $46{\times}36$ lightweight compared to existing antenna and This antenna can be used as transmission ommidirectional radiation pattern of propagation was compared to the input return loss than -10dB (VSWR 2:1) to allow communication from the resonant frequency band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.270-276
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• 2018

Fifth-generation communications are approaching, and they will require broadband antennas that include the existing LTE frequency band (1.7 GHz to 2.7 GHz) and the newly allocated frequency band (3.4 GHz to 3.7 GHz). Many kinds of antennas satisfy the required broadband characteristics, including the dual-element folded dipole antenna proposed in this paper. A zigzag line was used to make the antenna more compact. This was accomplished by reducing the physical length while maintaining the electrical length. To validate the proposed antenna, a prototype was fabricated using PCB (${\epsilon}_r$:4.4, Height: 1.6 mm) and its performance was evaluated. Results obtained by simulation and experiment showed good agreement.