• ETRI Journal
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• v.26 no.6
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• pp.555-559
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• 2004

We propose an efficient digital IF down converter architecture for dual-mode WCDMA/cdma2000 based on the concept of software defined radio. Multi-rate digital filters and fractional frequency conversion techniques are adopted to implement the front end of a dual-mode receiver for WCDMA and cdma2000. A sub-sampled digital IF stage was proposed to support both WCDMA and cdma2000 while lowering the sampling frequency. Use of a CIC filter and ISOP filter combined with proper arrangement of multi-rate filters and common filter blocks resulted in optimized hardware implementation of the front end block in 292k logic gates.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.181-185
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• 2017

In this paper, we propose an angle-of-arrival (AoA)-based local positioning system using a time-modulated array (TMA). The proposed system can determine a two-dimensional position using only two TMAs without any synchronization between the two receivers. The hardware for the proposed system consists of two commercial monopole antennas, a self-designed switch, and a well-known software-defined radio receiver. Furthermore, the location can be simply estimated in real time without the need for complicated positioning algorithms such as the MUSIC and ESPRIT algorithms. In order to evaluate the performance of our system, we estimated the position of the wireless node in an office environment. The position was estimated with a mean error of less than 0.1 m. We therefore believe that our system is appropriate for various wireless local positioning applications.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.261-273
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• 2016

Reconfigurable finite impulse response (FIR) filters whose filter coefficients and filter order change dynamically during run-time play an important role in the software defined radio (SDR) systems, multi-channel filters, and digital up/down converters. However, there are not many reports on such reconfigurable designs which can support dynamic variation of filter order and filter coefficients. The purpose of this paper is to provide an architectural solution for the FIR filters to support run-time variation of the filter order and filter coefficients. First, two straightforward designs, namely, (i) single-MAC based design and (ii) full-parallel design are presented. For large variation of the filter order, two designs based on (iii) folded structure and (iv) fast FIR algorithm are presented. Finally, we propose (v) high throughput design which provides significant advantage in terms of hardware and/or time complexities over the other designs. We compare complexities of all the five structures, and provide the synthesis results for verification.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.117-120
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• 2009

In this paper, a CR(Cognitive Radio) based on SDR(Software Defined Radio) is the technology combined a method selecting available frequency by recognizing surroundings with a learning algorithm continuously updating basic functions for communication and various environment parameters. Recently, as increasing demands with development of wireless communication service, CR is in the spotlight as technology using frequency resource efficiently. In order to apply CR system to the terminal and implement it, the research field to be preceded can be divided large as a hardware part and a software part. It can be also divided into RF processing and digital signal processing in the hardware part. In this paper, we look over preceding techniques required for applying CR system to the terminal, and research the forms of the terminal when they practically apply to the terminal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.501-509
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• 2011

Software defined radio(SDR) has a goal that places the analog-to-digital converter(ADC) as near the antenna as possible. But current technique actually can't do analog-to-digital converting about RF band signals. So one method is studying that samples RF band signals to IF band. One of the ways Sub-Sampling technique can convert signals from RF band to IF band without oscillator. If Sub-Sampling technique is used, over 2 bands can convert signals from RF band to IF band. But due to the filter performance in RF band, it is possible to generate interference between signals that is converted in low frequency band. The effect degrades performance. In this paper, we propose one method that uses time division multiplexing(TDM) method as a solution to avoid interference between signals. By doing TDM and Sub-Sampling at the same time that method can get signals without large changes of structures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.11-17
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• 2010

Multi-standard, multi-band, multi-service system to ensure a flexible interface between the SDR (Software Defined Radio) technology for the implementation of the Stability and Low-Power, Low-Calcualrion DDC (Digital Down Conversion) technology is essential. DDC technology consists of a digital channel filter. This is a typical digital filter because of the limited fisheries are vulnerable to overflow and rounding errors are drawbacks. In this paper, we overcome this disadvantage, we propose the structure of the DDC. The way WDF (Wave Digital Filter) Structural rounding error due to the structural resistance to noise. Therefore, This is the useful structure when the filter coefficients's word length is short. In addition, since IIR filters based on FIR filters based on the amount of computation is reduced because fewer than filter's tap. The proposed structure is used in DDC that CIC (Cascaded Integrator Comb) filter, WDF, IFOP (Interpolated Fourth-Order Polynomials) were analyzed with respect to, the results were confirmed by computer simulation.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.520-525
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• 2008

SCA(Software Communications Architecture)는 SDR(Software Defined Radio)를 위한 표준 플랫폼으로, 어떤 플랫폼에서도 SCA 표준을 이용하여 구현된 시스템이라면 SCA 규격을 지켜 작성된 소프트웨어 모듈을 실행할 수 있도록 하고 있다. SDR은 기존의 하드웨어로 구현하였던 무선 통신 시스템을 모두 소프트웨어로 구현하고자 하는 기술이지만, 임베디드 시스템의 경우에는 프로세서의 성능이 현저히 떨어지기 때문에 실시간 신호 처리를 보장할 수가 없다는 문제점이 있다. 따라서, 무선통신의 성능을 보장하기 위해서는 범용 프로세서와 함께 DSP나 FPGA와 같은 특화된 하드웨어의 사용이 필요하게 되었다. 이러한 경우에는 웨이브폼 어플리케이션 작성을 위해서 하드웨어와 소프트웨어의 파티셔닝도 고려해야 한다. 본 논문에서는 SCA 플랫폼에서의 웨이브폼 어플리케이션을 빠르게 생성하는 방법을 제안하여 다양한 하드웨어를 사용하는 플랫폼에서의 최종 웨이브폼 어플리케이션을 위한 설계 공간 탐색(Design space exploration)을 도와, 내장형 시스템에서도 효율적으로 실행 가능한 웨이브폼 어플리케이션을 개발할 수 있도록 한다.

• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.254-260
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• 2018

In this study, we suggest an emulator for generating multiple heterogeneous interference signals in the Korean radio frequency identification/ubiquitous sensor network (RFID/USN) frequency band. The proposed emulator uses only one universal software radio peripheral to generate multiple heterogeneous interference signals more economically. Moreover, the physical and media access control parameters can be adjusted in real time using the LabVIEW program, thereby making it possible to create various time-varying interference environments easily. As an example showing the capability of the proposed emulator, multiple interference signals consisting of a frequency-hopping RFID signal and two LoRa signals with different spreading factors were generated. The generated signals were confirmed in both frequency and time domains. From the experimental results, we verified that our emulator could successfully generate multiple heterogeneous interference signals with different frequency and time domain characteristics.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.55-59
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• 2014

Multi-band and multi-mode transmitters are needed for SDR and CR. Recently many types of polar transmitters have been studied in order to implement a multi-band and multi-mode transmitter. Polar transmitters have many advantages, such as a simple structure, high efficiency and etc. In this paper we consider the number of D/A bit and the effects of a delay mismatch as design parameters for implementing polar transmitters. From the simulation we know that a 10 bit D/A is sufficient and a delay mismatch must be maintained small than 1/64 chip for satisfying the spectrum mask characteristics. We implement a polar transmitter based on the design parameters and the measured output signal meet the spectrum mask of 800MHz CDMA.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1216-1221
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• 2005

The GPS software receiver based on the SDR(Software Defined Radio) technology provides the ability to easily adopt other signal processing algorithms without changing or modifying the hardware of the GPS receiver. However, it is difficult to implement the GPS software receiver using a commercial processor because of heavy computation load for processing the GPS signals in real time. This paper proposes an efficient GPS signal processing scheme and correlator structure to reduce the computation load for processing the GPS signal in the GPS software receiver, which uses a patterned look-up table method to generate the correlation value between the GPS signals and the replica signals. In this paper, it is explained that the computation load of the proposed scheme is much smaller than that of the previous GPS signal processing scheme. Finally, the processing time of the proposed scheme is compared with that of the previous scheme, and the improvement is shown from the viewpoint of the computation load.