• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.93-102
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• 2005

This paper presents an interface configuration between Access Point(AP) and Radio Over Fiber (ROF) transceiver for the wireless internet system. The wireless internet could provides 60km/h mobility and 50Mbps IP based data services for each mobile terminal. Thus, cost effective cell infrastructure is inevitably required. This paper suggests an interface configuration between AP and passive integrated picocell(PIP) involving ROF links. Nonlinear characteristics of ROF link using a typical FP transceiver are measured for wireless internet applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.188-194
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• 2011

We analyze transmission performance of radio frequency signal in WDM-ROF (wavelength division multiplexing - radio over fiber) system employing photonic crystal fiber. In a WDM-ROF system employing conventional single-mode fiber, transmission performance of radio frequency signal is analyzed depending on each WDM channel. In this case, each WDM channel experiences power fluctuation of received RF signal in remote node because of double sidebands of the modulated signal and wavelength dependent dispersion of single mode fiber. This RF power fluctuation acts as a design constraint in viewpoint of system design. By employing photonic crystal fiber (PCF) with dispersion compensation characteristics, the transmission performance of RF signal can be improved compared with the case with SMF only.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.53-62
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• 2005

This paper presents an interface configuration between the Access Point(AP) of Wibro and Radio Over Fiber(ROF) transceivers for the wireless broadband internet system. The wireless internet could provides 60km/h mobility and 50Mbps IP based data services for each mobile terminal. Thus, low cost of each cell is inevitably required. This paper suggests an interface configuration between AP and Passive Integrated Picocell(PIP) involving ROF links. Characteristics of a typical Fabry-Perot ROF link and a PIP using a passive Electro-Absorption Modulator(EAM) are described and measured for wireless internet applications. In addition, results of RF coverage of a PIP have been shown.

• Current Optics and Photonics
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• v.8 no.4
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• pp.345-354
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• 2024

The bit walk-off effect caused by fiber dispersion and carrier reuse in the base station (BS) are two key problems in radio-over-fiber (ROF) systems. In this paper, a novel frequency-octupling ROF system based on the Mach-Zehnder modulator (MZM) is proposed, which can overcome the bit walk-off effect and realize carrier reuse by inserting pilot signals. Theoretical analysis and simulation verification of the system are carried out. Under the condition of a Q factor greater than 6, the optical fiber transmission distance of the upper and lower links is more than 290 km and 80 km, respectively. The influence of the main device parameters of the system on the Q factor is analyzed when they deviate from their designed values. The system designed in this paper can not only effectively overcome the bit walk-off effect, but also solve the problem of downlink performance degradation and the limitation of tunability caused by conventional carrier reuse in ROF. The system can greatly increase the transmission distance and improve the performance of the system and has an important application prospect in ROF.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.17-23
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• 2006

In this paper, Adjacent Channel Power Ratio (ACPR) of wireless Orthogonal Frequency Division Multiplexed (OFDM) system interconnected with Radio over Fiber (RoF) link is analyzed for broadband convergence network applications. Unlike previous results, ACPR of the total link, which is involved with Radio Frequency (RF) amplifier as well as ROF link, at 5.8 GHz in IEEE 802.11a environment is simulated and compared at both system ends.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.935-942
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• 2006

The performance of ROF systems can be severely degraded due to nonlinear effects in the channel. Also, Orthogonal Frequency Division Multiplex(OFDM), as a standard for broadband wireless and mobile internet networks, is being proposed for deployment with ROF systems to facilitate the total performance of a system. In this paper, at first, the performance of the OFDM-based RoF system with a Mach-Zehnder(MZ) modulator distortion effects has been analyzed at 5.8GHz. Evaluation of mean-squared error of the proposed OFDM-RoF system was carried out to compare with the conventional single carrier system based RoF link after the modulator distortion case and also for fixed signal to noise ratio(SNR) of 20dB using undistorted OFDM signal. Nominal and offset baising pre-distortion techniques are applied in proposed system to linearize the OFDM-RoF link. Finally, a comparison between the aforementioned pre-distortion techniques applied showed important observation in terms of distortion-free dynamic range and SNR to choose offset pre-distortion technique for our proposed system.

• ETRI Journal
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• v.28 no.3
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• pp.393-396
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• 2006

This letter proposes a new impedance matching scheme of a traveling wave electro-absorption modulator (TWEAM) module for a 60 GHz band radio-over-fiber (ROF) link. A microstrip band pass filter (BPF) was used to achieve impedance matching at the 60 GHz band, and termination resistance was carefully designed to obtain an input impedance close to $50\;{\Omega}$. Also, a bias circuit for the device was designed in the module. The measured return loss and frequency response show that the modulator module observes the characteristics of a filter without the need of a further tuning process.