Soo-Yong Jung

TDOA-based optical wireless indoor localization using LED ceiling lamps

We propose an optical wireless indoor localization using light emitting diodes (LEDs) and demonstrate it via simulation. Unique frequency addresses are assigned to each LED lamp, and transmitted through the light radiated by the LED. Using the phase difference, time difference of arrival (TDOA) localization algorithm is employed. Because the proposed localization method used pre-installed LED ceiling lamps, no additional infrastructure for localization is required to install and therefore, inexpensive system can be realized. The performance of the proposed localization method is evaluated by computer simulation, and the indoor location accuracy is less than 1 cm in the space of 5m x 5 m x 3 m.

White LED ceiling lights positioning systems for optical wireless indoor applications

An indoor positioning system based on white LED communications is proposed and demonstrated. This positioning system shows that mean of distance errors is 0.651 cm in the space of 30 cm × 30 cm × 50 cm.

Received signal strength ratio based optical wireless indoor localization using light emitting diodes for illumination

We propose optical wireless indoor localization using light emitting diodes (LEDs). In the proposed method, four LED lamps for illumination are employed and strength ratio between received LED light signals is utilized for location estimation.

Colorless upstream transmission using remote self-injection locked reflective SOA for WDM-PON

Colorless upstream transmission is demonstrated using a self-injection locked RSOA for a range of 24 nm, achieving error free performance after upstream transmission at 1.25-Gb/s over 20-km SMF. The receiver sensitivities were of < -28.5 dBm.

Correction of Nonlinear Frequency Sweep in Frequency-Modulated Continuous-Wave Laser Range Sensor

We propose a linearization method for reducing the effect of nonlinear frequency sweep in a frequency-modulated continuous-wave (FMCW) based laser range sensor. In FMCW laser range sensors, nonlinear frequency sweep can severely degrade the measurement accuracy because it gives the system ambiguity when determining the target range. In general, voltage controlled oscillators (VCO) which are used for frequency modulation show nonlinear frequency sweep property even though the input voltage signal is a linear ramp signal. To solve this problem, we adopt an additional fixed delay structure to extract the nonlinearity and compensate it. The proposed linearization method has been worked out through the numerical process and the simulation, and this method effectively eliminates the nonlinear frequency sweep problem.

Mutually Injection-Locked Tunable Laser Based on GS-RSOAs for L-Band Generation

We propose a mutually injection-locked tunable (MILT) laser for L-band generation based on arrayed waveguide grating and gain-saturated reflective semiconductor optical amplifiers. The laser generates a 3-dB bandwidth less than 0.05 nm and a high and uniform sidemode suppression ratio (SMSR >;52 dB, ΔSMSR >;3 dB) over 40 L-band wavelengths. Using an MILT laser greatly reduced the phase noise, which is measured to be -107.83 dBc/Hz at a frequency of 10-kHz offset from the center. Furthermore, the 1.25-Gb/s directly modulated transmission performance of the MILT laser shows that there is a power penalty of ~ 0.2 dB over a 20-km single mode fiber.

All-optical wavelength conversion in GC-RSOA

We propose a new all-optical wavelength conversion technique based on cross gain modulation (XGM) in gain clamped reflective semiconductor optical amplifier (GC-RSOA). The proposed technique uses the seed light reflected from the FBG as probe signal, thereby avoiding the need of an external seed source for wavelength conversion.