• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.114-114
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• 2004

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1134-1141
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• 1999

In this paper, we implement an optical code division multiple access(OCDMA) system and analyze the performance of the implemented system. In the implemented system, a transmitter encodes input data into optical pulses by using laser diode, and spreads the encoded pulses in an encoder which consists of 4 stage delay lines. The decoder which is the same structure as that of encoder delays and combines the spreaded pulses, and thus recovers the original data. At first, we discuss the auto- and cross-correlations of OCDMA signals under both environments of single user and multi-users, and then verify the simulation results with experimental results. We also evaluate the effect of a number of stages of delay line and code length on the system performance through computer simulations. As experimental results we can see that if the decoder have the same configuration as that of encoder, the peak auto-correlation characteristics can be achieved, and thus we can recover the original data from received data. As simulation results we can see that although bit error rate decreases as code length decreases or the number of stage of delay line increases, it is difficult to implement the system because the pulse width becomes narrow. From the results, we can apply CDMA technologies to optical communication networks.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.172-173
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• 2001

다중 광접속 방법 중 CDMA는 많은 수의 주소(개별 사용자를 위한 채널)를 제공하고 광 패킷 전송 방법에 있어서는 패킷들의 충돌을 피하기 위한 복잡한 장치를 필요로 하지 않는다는 장점을 가지고 있다. LED와 같은 Incoherent 광원을 이용하는 광 CDMA를 위한 여러 가지 광 코드와 암호화 방식이 제안되어 왔으며, 파장/시간 이차원 광 코드를 이용하는 방식은 AWG mux/demux 또는 AWG 라우터를 이용하여 광 코드가 용이하게 구현될 수 있음이 보고된 바 있다. (중략)

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.10-15
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• 2010

Good performance of spectral-amplitude-coding optical CDMA can be obtained using codes based upon Hadamard matrices, but Hadamard codes have very restrictive code lengths of $2^n$. In this paper a new code family, namely extended Hadamard code, is proposed to relax the code length restriction and the number of simultaneous users. The improved performance of the proposed system is analysed with the consideration of phase-induced intensity noise(PIIN).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.8
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• pp.5-9
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• 2011

Spectral-amplitude-coding optical CDMA systems using codes based upon Hadamard matrices have very restrictive code lengths of $2^n$ and high phase-induced intensity noise(PIIN). In this paper a new code family, namely modified Hadamard code, is proposed to relax the code length restriction and the number of simultaneous users. The improved performance of the proposed system is analysed with the consideration of noise.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.12
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• pp.31-44
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• 1996

Since optical delay line signal processing which utilizes optical fiber as delay line elements can provide high speed and broadband signal processing, the optical delay line signal processing has numerous applications. Recently, many research papers which optical delay line signal processing techniques are being applied to OCDMA are published. The author has published paper on the design method for optical fiber filters of lattice structure. However, the previous design method does not realize the transfer function all the time. It can be realized with constraints. In this paper, we propose the design method that can realize the transfer function all the time without any constraints for the optical fiber filter of lattice structure.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.27-32
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• 2014

Two-dimensional hybrid codewords are generated by using each row of identity matrix for spatial encoding and nonideal symmetric balance incomplete block design(BIBD) code for spectral encoding. This spatial/spectral optical code-division multiple-access (OCDMA) network uses single-balanced detectors to abstract the desired information bits and to eliminate the multiple-access interference(MAI). Analytical results show that the number of simultaneous users increases significantly by using the proposed hybrid codes.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.6
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• pp.379-392
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• 2016

This paper presents the design and simulation of a laser power beaming (LPB) system for an electric vehicle that establishes an optimal power transmission path based on the received signal strength. The LPB system is possible to transfer power from multiple transmitters to a single receiver according to the characteristics of the laser and the solar panel. When the laser beams of multiple transmitters aim at a solar panel at the same time, the received power is the sum of all energy at a solar panel. Our proposed LPB system consists of multiple transmitters and multiple receivers. The transmitter sends its power characteristics as optically coded pulses with a class 1 laser beam and powers as a high-intensity laser beam. By using the attenuated power level, the receiver can estimate the maximum receivable powers from the transmitters and select optimal transmitters. Throughout the simulation, we verified the possibility that different LPB receivers were achieved their required power by the optimal allocation of the transmitter among the various transmitters.