• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.3
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• pp.219-222
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• 2007

In this paper, we have designed microstrip antenna of 800[MHz] band. It will be able to integrate TRS(Trunked Radio System), GSM(Global System for Mobile telecommunication) band including the CDMA(Code Division Multiple Access) band. we designed repeater and a base station antenna which is possible at the ship and marine of safety. It is improves a narrow bandwidth problem of microstrip antenna. It had L-shaped feeding structure at a rectangular patch and added the parallel L-slot that used a duplex resonance effect. Also for the improvement of profit the stack with the perpendicular. Designed frequency bandwith(VSWR 2:1) of the antenna showed good characteristic of 789${\sim}$1046[MHz] to 292[MHz](36%). Also the E-plan and H-plan all profit 6.4[dBi] above, the 3[dB] beam width showed the characteristic over the E-plan $44.7^{\circ} and H-plan $61.8^{\circ} to be improved.

• Journal of Communications and Networks
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• v.13 no.1
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• pp.70-76
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• 2011

This paper presents the unified user equipment (UE) baseband modulation and demodulation (modem) hardware platform architecture to support multiple radio access technologies. In particular, this platform selectively supports two systems; one is HEDGE system, which is the combination of third generation partnership project (3GPP) Release 7 high speed packet access evolution (HSPA+) and global system for mobile communication (GSM)/general packet radio service (GPRS)/enhanced data rates for GSM evolution (EDGE), while the other is LEDGE system, which is the combination of 3GPP Release 8 long term evolution (LTE) and GSM/GPRS/EDGE. This is done by applying the flexible pin multiplexing scheme to a hardwired pin mapping process. On the other hand, to provide stable connection, high portability, and high debugging ability, the stacking structure is employed. Here, a layered board architecture grouped by functional classifications is applied instead of the conventional one flatten board. Based on this proposed configuration, we provide a framework for the verification step in wireless cellular communications. Also, modem function/scenario test and inter-operability test with various base station equipments are verified by system requirements and scenarios.

• International Journal of Computer Science & Network Security
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• v.24 no.4
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• pp.197-205
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• 2024

This paper presents a fully automated stand-alone irrigation system with GSM (Global System for Mobile Communication) module. Solar energy is utilized to power the system and it is aimed to conserve water by reducing water losses. The system is based on a DC water pump that draws energy from solar panels along with automated water flow control using a moisture sensor. It is also fitted with alert and protection system that consists of an ultrasonic sensor and GSM messages sender that transmits signals showing the levels of the water in the reservoir and the battery charge. The control system is designed to stop the water pump from pumping water either when the battery level drops to equal or less than 10% of its full charge, or when the water level becomes less than 10 cm high in the reservoir. The experimental results revealed that the system is appropriate to use in remote areas with water scarcity and away from the national grid.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.16-20
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• 2011

In this paper, we designed and implemented an internal multi-band folded monopole antenna for mobile handset. The proposed antenna covers Global System for Mobile Communications (GSM900: 880~960 MHz), Digital Communications System (DCS: 1710~1880 MHz), US-Personal Communications Service (US-PCS: 1850~1990 MHz), Bluetooth(2400~2484 MHz), WiMAX(3400~3600 MHz), and Wireless Local Area Network (WLAN: 5150~5350 MHz, 5725~5875 MHz) band for Voltage Standing Wave Ratio $(VSWR)\;{\le}\; 3$. The measured peak gains of the implemented antenna are -1.78dBi at 920MHz, 2.72dBi at 1795MHz, 2.25dBi at 1920MHz, 2.34dBi at 2442MHz, 2.11 dBi at 3550MHz, and 2.04 dBi at 5250MHz.

• International Journal of Contents
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• v.3 no.4
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• pp.8-14
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• 2007

This study focuses on modeling mobile 3D game engine and suggesting modified skinned-mesh schema based on JSR-184 in order to improve the performance in terms of memory consumption and time complexity. Most of the 3D games have used OpenGL-ES low-level APls, which may limit portability and fast developing time. Hence, the 3D mobile game engine providing high-level APls which works on GSM (Global System for Mobile Communication) phones on J2ME, is proposed here in order to optimize the performance for Java environment abiding JSR-184 standard. To prove performance enhancement, skinned-mesh schema on JSR-184 engine is modified and tested. The experimental results are shown.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.80-83
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• 2016

In this paper, a simplified uplink transmission procedure is proposed for reducing energy consumption and improving lifetime of CIoT devices. In the proposed procedure, the CIoT devices register information on their service and traffic to the networks, and the networks statically allocate pre-defined amounts of radio resources when the CIoT devices have requested permission for their uplink transmissions. This paper provides details of the proposed procedure comparing with those of the current GSM procedure, and defines detailed operations of the devices and the networks for the proposed one. This shows that the proposed scheme can effectively support CIoT services on GSM networks.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.32-41
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• 1996

We propose the improved GMSK (gaussian-filtered minimum shift keying) quadrature modulator using the FIR(finite impulse response )filter whose coefficients are obtained form the differnce of phase response, and design its ASIC (applicaton specific integrated circuit) which can be used for GSM (global system for mobile communication) digital cellular system and DCS 1800 (digital cellular system at 1800MHz) personal communication system. Input data become quantized I and Q channel 10 bit signal through cosine and sine ROM mapping after being filtered by the FIR filter whose normalized bandwidth is 0.3 and designed by considering intersymbol interference as well as sampling ratio. These two signals become the GMSK modulated I and Q channel signal through DAC (digital-to-analog converter) and 7th order analog chebyshev LPF(low pass filter) respectively. The difference between the ideal analog signal and its digitized signal is analyzed in terms of sampling noise, quantization noise, truncation noise and coefficient noise. And the effect of the LPF following the DAC is considered. The ASIC design of the GMSK quadrature modulator is also confirmed by an experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.984-989
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• 2008

In this paper, we will design a 800MHz broadband antenna after a problem of the narrow bandwidth is improved. This multiple band antenna unifies the CDMA(Code Division Multiple Access), GSM(Global System for Mobile Telecommunication) and TRS(Trunked Radio System) band in the UHF band, and then it is possible at the shore base station or repeater as the commercial use. It used the duplex resonance effect it had the L-shared feeding structure which adds the U-slot. And it improved profit using stack structure. It was measured that the frequency bandwidth of the designed antenna which is planed $792{\sim}1040MHz$ with 248MHz(33%). And the antenna gain is 9.4dBi, 3dB beam width $60^{\circ}$ in radiation pattern.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.805-814
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• 2012

Intermittent or periodic signals with undulating amplitudes of mobile devices cause interference noise at audible frequency to the sound system which is installed nearby. In this regard, it is recently issued that the intermittently transmissions of LTE mobile phones cause the interference noises with sound systems, similar to that of GSM mobile phones. For retaining the immunity to noises, a national regulation KN20 suggests a 1 kHz AM 80 % and a CDMA modulation signal as reference signals for immunity test of sound and television broadcast receiver. In this paper, the effects of interference noises of AM and CDMA are compared with those of GSM and LTE, and the improvement of reference signal for national immunity test of sound systems is suggested. It is recommended to delete the CDMA modulation signal from reference signals for immunity test because it hardly cause interference noise with sound systems. On the other hand, it is desirable to select the modulation signal of LTE instead of CDMA as a reference signal for immunity test of sound system and television broadcast receiver because many people use the LTE service and it is analysed that the LTE signal causes considerable interference noises.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.321-333
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• 2005

With the limited frequency spectrum and an increasing demand for cellular communication services, the problem of channel assignment becomes increasingly important. However, finding a conflict free channel assignment with the minimum channel span is NP hard. As demand for services has expanded in the cellular segment, sever innovations have been made in order to increase the utilization of bandwidth. The innovations are cellular concept, dynamic channel assignment and hierarchical network design. Hierarchical network design holds the public eye because of increasing demand and quality of service to mobile users. We consider the frequency assignment problem and the base station placement simultaneously. Our model takes the candidate locations emanating from this process and the cost of assigning a frequency, operating and maintaining equipment as an input. In addition, we know the avenue and demand as an assumption. We propose the network about the profit maximization. This study can apply to GSM(Global System for Mobile Communication) which has 70% portion in the world. Hierarchical network design using GA(Genetic Algorithm) is the first three-tier (Macro, Micro, Pico) model, We increase the reality through applying to EMC (Electromagnetic Compatibility Constraints). Computational experiments on 72 problem instances which have 15${\sim}$40 candidate locations demonstrate the computational viability of our procedure. The result of experiments increases the reality and covers more than 90% of the demand.