• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.65-68
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• 2000

In this paper, as a compatible software radio transmission system, Digital-Radio conversion system which can directly change the digital signal generated by the logic circuit into radio signal is proposed. By the vector synthesis method, the digital signals can change directly into radio signal. If such a circuit is realized, RF circuit and an antenna can be composed by the simple one device, and the radio is directly controlled and performed by the software processing which is the essence of software radio. This Digital-Radio conversion system of this paper give many number of communication channels being offered by PN code and offer a hardware design flexibility by digitization, therefore it decrease the percentage ratio of hardware of system and give a more flexible function of software basis. In this paper, this proposed Digital-Radio conversion system is called D/R converter, and the principle of this D/R converter, radio signal generation algorithm is explained and the performance characteristics of proposed algorithm is shown in time base by the computer simulation method.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.122-127
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• 2012

The purpose of this study is to know about the interference on FM Radio channel from HD Radio signal. In Korea, a data service channel, named DARC is operated by a major FM radio broadcaster which has national wide service area. Therefore, an analysis of the interference on FM radio channel with DARC data channel from HD Radio, most recently developed digital radio system. Technical parameters of FM radio with DARC data channel and HD Radio system are considered for this simulation. As results some interference generated because of HD Radio signal according to its signal allocation and service mode of HD Radio.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.2
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• pp.131-137
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• 2000

In this paper, as a compatible software radio transmission system, Digital-Radio conversion system which can directly change the digital signal generated by the logic circuit into radio signal is proposed. By the vector synthesis method, the digital signals can change directly into radio signal. If such a circuit is realized, RF circuit and an antenna can be composed by the simple one device, and the radio is directly controlled and performed by the software processing which is the essence of software radio. This Digital-Radio conversion system of this paper give many number of communication channels being offered by PN code and offer a hardware design flexibility by digitization, therefore it decrease the percentage ratio of hardware of system and give a more flexible function of software basis. In this paper, the principle of digital to radio signal generation algorithm is explained and the performance characteristics of proposed algorithm is shown in time base by the computer simulation method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2685-2690
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• 2014

WPS determines position via a two-step process. In the construction phase, a radio map is constituted by collecting radio information signals. Positioning procedure is a step of comparing the radio signal newly acquired with the radio map. If the signals collected and the radio map are different the accuracy decreases. Even though the rate of accuracy is different according to positioning algorithms, accuracy drop is an issue common to all WPS systems. Signal strength fluctuation is caused by the malfunction of the device that receives positioning signals, obstruction and channel interference, etc. In this paper, in order to solve the problem caused by signal strength change, we propose a new radio map construction technique. The proposed method is intended to constitute a strong radio map to changes in the signal strength and updated by collecting the signal strength changes to the radio map. The use of this method is expected to enhance the accuracy of WPS by actively counteracting signal fluctuation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.20-33
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• 2015

Spectrum sensing is a key component of cognitive radio. The prediction of the primary user status in a low signal-to-noise ratio is an important factor in spectrum sensing. However, because of noise uncertainty, secondary users have difficulty distinguishing between the primary signal and an unauthorized signal when an unauthorized user exists in a cognitive radio network. To resolve the sensitivity to the noise uncertainty problem, we propose an entropy-based spectrum sensing scheme to detect the primary signal accurately in the presence of an unauthorized signal. The proposed spectrum sensing uses the conditional entropy between the primary signal and the unauthorized signal. The ability to detect the primary signal is thus robust against noise uncertainty, which leads to superior sensing performance in a low signal-to-noise ratio. Simulation results show that the proposed spectrum sensing scheme outperforms the conventional entropy-based spectrum sensing schemes in terms of the primary user detection probability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3789-3809
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• 2014

Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8A
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• pp.730-740
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• 2011

The Korean radio broadcasting system is analog. Compared with digital radio, the analog radio decreases the frequency efficiency. HD Radio is the method where the digital signal is transmitted on either side of the analog PM signal. Therefore, without relocating the analog frequency can transmit digital signals. If interference between analog and digital signal occurs it is impossible to receive smoothly, so HD Radio interference with existing analog PM will be analyzed. In this paper, based on Mt.Gwae-Bang stations within +-400kHz frequency of l03.5MHz, and to use the station to station by specifying the HD Radio channel interference, place the structures were analyzed. Through this paper, the reader of a digital radio frequency interference in the system know that it may obtain information about.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.59-61
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• 2022

Among indoor positioning system techniques using wireless APs, fingerprint techniques collect Mac information and reception strength of APs before performing positioning, build a radio map, and compare it with AP information collected during positioning. However, the existing Radio Map construction method has a problem in that signal interference occurs due to collisions of numerous APs depending on the indoor environment, and the signal strength search result is not always constant. Therefore, this paper compares the existing fixed radio map construction method and the variable radio map construction technique that actively analyzes and constructs the measurement area itself according to signal strength.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.1-10
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• 2018

In cognitive radio (CR), secondary users (SUs) are able to sense the absence of primary users (PUs) in the spectrum. Then, SUs use this information to opportunistically access the licensed spectrum in the PUs' absence. In this paper, we present an implementation of real-time video transmission with spectrum-sensing between two points using GNU Radio and a National Instruments 2900 Universal Software Radio Peripheral (USRP). In our project, spectrum-sensing is implemented at both transmitter and receiver. The transmitter senses the channel, and if the channel is free, a video signal (which could be a real-time signal from a video file) will be modulated and processed by GNU Radio and transmitted using a USRP. A USRP receiver also senses the channel, but in contrast, if the channel is busy, the signal is demodulated to reproduce the transmitted video signal. This project brings in several challenges, like spectrum-sensing in the devices' environment, and packets getting lost or corrupted over the air.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.94-100
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• 2012

Radio interference has been occurring in mobile communication services on the southern seashore in Korea. Monitoring the radio interference signal revealed that the main reason for the radio interference was a radio ducting signal coming from the seaside of Japan. In this paper, we have analyzed the effect of interference on WiMAX service using a 2.5 GHz frequency band between Korea and Japan. We focus on the interference scenario from base station to base station and we use the Minimum Coupling Loss (MCL) method for interference analysis and the Advanced Propagation Model (APM) for calculating the propagation loss in ducts. The propagation model is also compared with experimental measurement data. We confirm that the interfering signal strength depends on the antenna height and this result can be applied to deployment planning for each system with an interference impact acceptable to both parties.