• Journal of Positioning, Navigation, and Timing
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• v.4 no.4
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• pp.173-180
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• 2015

In this study, an algorithm that detects a spoofing signal for a GPS L1 signal was proposed, and the performance was verified through RF spoofing signal simulation. The proposed algorithm determines the reception of a spoofing signal by detecting a correlation distortion of GPS L1 C/A code caused by the spoofing signal. To detect the correlation distortion, a detection criterion of a spoofing signal was derived from the relationship among the Early, Prompt, and Late tap correlation values of a receiver correlator; and a detection threshold was calculated from the false alarm probability of spoofing signal detection. In this study, an RF spoofing environment was built using the GSS 8000 simulator (Spirent). For the RF spoofing signal generated from the simulator, the RF spoofing environment was verified using the commercial receiver DL-V3 (Novatel Inc.). To verify the performance of the proposed algorithm, the RF signal was stored as IF band data using a USRP signal collector (NI) so that the data could be processed by a CNU software receiver (software defined radio). For the performance of the proposed algorithm, results were obtained using the correlation value of the software receiver, and the performance was verified through the detection of a spoofing signal and the detection time of a spoofing signal.

• Journal of Digital Contents Society
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• v.10 no.4
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• pp.605-614
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• 2009

The software-defined radio (SDR) is a radio communication technology that can reconfigure necessary application software on a common hardware platform to deal with several kind of radio communication environment. It is necessary for a system that can control and analyze functionalities of a system in order to verify the SCA-based reconfigurable middleware platform, SCARLET that implements the SDR technology. In this paper, we propose and implement the architecture of the waveform manager that is connected with SCARLET and performs management and control functionalities. We verify the performance of the waveform manager by testing each functionality of the overall system that uses the SCARLET middleware platform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1286-1295
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• 2007

This paper proposes, based on a bandpass sampling theory, a novel method to find valid sampling frequency range and minimum sampling rate with low computational complexity for downconversion of N bandpass radio frequency(RF) signals, under application of all possible signal placements(full permutations) in a IF stage. Additionally, we have developed a complexity-reducing method to obtaine the opttimal and minimal sampling rate for supporting the user-wanted guard-band or spacing between adjacent downconverted signal spectrums. Moreover, we have verified through comparisons with other methods that the proposed methods have more advantageous properties.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.43-50
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• 2010

DDC(Digital Down Converter) is a conversion technology to decimate to a lower sampling rate and DDC for the future development of communications technology has the necessary skills. So, it has been recognized in the wireless and the SDR(Software Defined Radio) system as essential components. In addition, research is underway on spectrum sensing for efficient communications environment due to the shortage of frequency resources. In this paper, the DDC systems were analyzed for CIC(Cascaded Integrator Comb) Filter, WDF(Wave Digital Filter), SRC(Sample Rate Conversion) each module. Moreover, we proposed a linkage effectively between DDC system and Spectrum Sensing for improve the efficiency of use of frequency by computer simulations. The simulation results of the DDC system was applied to the spectrum sensing capabilities. Also, performance and complexity of the results were derived and proposed system was the result of the check.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.257-260
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• 2004

This paper describes the software download framework for SDR(Software Defined Radio). SDR is expected to solve the compatibility problem among various mobile communication standards so that people can use the same device for different wireless network. We integrated the SDR software download process into Jini architecture, and modified Jini's several functions. We implemented this proposed framework on a Linux and windows operating systems with Java programming language. With Java platform, we can easily transfer this framework into hand-held devices.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.4
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• pp.81-87
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• 2016

Recently, as the heterogeneous network (HetNet) has been deployed widely to support various kinds of Radio Access Networks(RANs) with a combination of Macro, Pico, and/or Femto cells, research and standardization efforts have been very active regarding the concept of Licensed Shared Access (LSA) for supporting spectrum sharing. In order for a mobile device to efficiently support the spectrum sharing, the mobile device shall be reconfigurable, meaning that its radio application code has to be adaptively changed in accordance with the hopping of desired spectral band. Especially, Working Group 2 (WG2) of Technical Committee (TC) Reconfigurable Radio System (RRS) of European Telecommunications Standards Institute (ETSI) has been a main driving force for developing standard architecture for Multi-mode Mobile Device (MD) that can be applied to the LSA system. In this paper, we introduce the Multi-mode MD architecture for supporting LSA-based spectrum sharing. An implementation of a test-bed of Multi-mode MD is presented in order to verify the feasibility of the standard MD architecture for the purpose of LSA-based spectrum sharing through various experimental tests.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1339-1349
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• 2008

In this paper, a nonlinear relationship between an input complex envelope and an output complex envelope of m-th harmonic zone is theoretically analyzed, and AM/$AM_m$ and AM/$PM_m$ are defined. A scheme to extract these characteristics from measured in-phase and quadrature-phase data is suggested. The proposed analysis is verified with a fundamental-fundamental and fundamental-third harmonic measurements for a InGaP power amplifier(PA). Based on the harmonic-band nonlinear analysis and extraction scheme, a new technique to send a signal in m-th harmonic band with a harmonic signal Linearization Digital Predistortion(DPD) scheme is presented. A numerical analysis and a Look-Up Table(LUT) based DPD algorithms to linearize output signal on m-th harmonic zone are developed. For a 16- and a 64-QAM input signals, a DPD for third harmonic signal linearization is implemented, and output spectrum and signal constellation are measured. The wholly distorted signals are linearized, and thus the measured Error Vector Magnitudes (EVM) are 6.4 % and 6.5 % respectively. The results show that a proposed scheme linearizes a nonlinearly distorted harmonic band signals. The proposed nonlinear analysis and predistortion scheme can be applied to multiband transmitter in next generation software defined radio(SDR)/cognitive radio(CR) wireless system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.1
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• pp.117-123
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• 2012

This paper implements mobile Worldwide Interoperability for Microwave Access (WiMAX) receiver using Software Defined Radio (SDR) technology. SDR system is difficult to implement on the mobile handset because of restrictions that are computing power and under space constraints. The implemented receiver processes mobile WiMAX software modem on Open Multimedia Application Platform (OMAP) System on Chip (SoC) and Field Programmable Gate Array (FPGA). OMAP SoC is composed of ARM processor and Digital Signal Processor (DSP). ARM processor supports Single Instruction Multiple Data (SIMD) instruction which could operate on a vector of data with a single instruction and DSP is powerful image and video accelerators. For this reason, we suggest the possibility of SDR technology in the mobile handset. In order to verify the performance of the mobile WiMAX receiver, we measure the software modem runtime respectively. The experimental results show that the proposed receiver is able to do real-time signal processing.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.381-388
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• 2022

In 2021, development of a regional satellite navigation system called KPS was approved. In this regard, various studies are in progress, but there is no published signal model. So, in relation to the user segment, it is necessary to design a user receiver, but there is no information. Therefore, in this paper, we assume a signal model that can be a candidate signal for KPS based on related studies. This signal uses CNAV-2 structure navigation message, truncated Gold code and BPSK modulation. Based on this signal, a simulator is designed that can be used for receiver design later. The simulator consists of a signal generator and a signal transmitter, and is verified using a software receiver and spectrum analyzer.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.767-769
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• 2002

A novel RE configurable device composed by bare-chip, bumps and board are proposed. We call this "Field-Programmable RF Gate Array (FPRA)," This device, a kind of programmable system packages, has a potential to be applied to wireless communication terminals such as software-defined radio.