ABSTRACT
Orthogonal frequency division multiplexing (OFDM) has recently gained substantial interest in high capacity optical fiber communications. Unlike wireless systems, optical OFDM systems are constrained by the limited resolution of the ultra high-speed digital-to-analog converters (DAC) and analog-to-digital converters (ADC). Additionally, the situation is exacerbated by the large peak-to-average power ratio (PAPR) inherent in OFDM signals. In this paper, we study the effects of clipping and quantization noise on the system performance. We analytically quantify the introduced distortion as a function of bit resolution and clipping ratio, both at the DAC and ADC. With this we provide a back-to-back signal-to-noise ratio analysis to predict the bit error rate of the system, assuming a fixed received optical power and ideal electrical-optical-electrical conversion. Simulation and experimental results are used to confirm the validity of the expressions.
ABSTRACT
We select the optimum design parameters for real-time optical OFDM transceivers running at 25 Gb/s and analyze power consumption and ASIC footprint for a variety of configurations based on synthesis for a 65nm standard-cell library. Experiments quantify the effects of modulation format and the number of IFFT/FFT points used in transceivers.
