Moment Generating Function for the Rigorous Performance Assessment of Direct-Detection Baseband OFDM Communication Systems

Abstract

Abstract-A new moment generating function (MGF) isproposed to assess rigorously the performance of optically preamplified receivers with direct-detection employing baseband orthogonal frequency division multiplexing (OFDM). By comparison with Monte Carlo simulation, the proposed MGF-based method shows very good accuracy when predicting the bit error probability for arbitrary optical and electrical filters, different numbers of OFDM subcarriers, and double sideband and single sideband optical OFDM signals. Its good accuracy when estimating the bit error probability in each individual subcarrier is also demonstrated. The new MGF-based method exhibits a significant improvement of accuracy when compared to the MGF-based method previously reported in the literature, especially for filter bandwidths not exceeding the OFDM signal bandwidth, which is the range corresponding to the optimum filter bandwidth.

Performance evaluation of direct-detection OFDM optical receivers with RF down-conversion

“…T is the time interval between two successive samples taken by the ADC; T is the total duration of the OFDM symbol; and o t is the first sampling time instant of the OFDM symbol corresponding to 1 γ = [3]. The ADC samples are applied to the FFT block and the equalization is performed by multiplying the symbols at the FFT output in each n-th subcarrier by the coefficients…”

“…The theory developed to evaluate the performance of optical DD baseband OFDM optical receivers from the MGF is derived in [3]. The main contribution of this work is to include the I/Q RF demodulator influence on that development.…”

“…In [3], an analytical method based on the moment generating function (MGF) has been proposed to assess the performance of DD optical receivers with OFDM baseband signals. However, most DD-OFDM communication systems move the OFDM spectrum from the baseband region where undesirable intermodulation distortion products fall, by performing radio-frequency (RF) up-conversion at the transmitter side, which demands an RF down-conversion at the DD-OFDM optical receiver side.…”

“…In this work, the method proposed in [3] is generalized to DD-OFDM optical receivers with intermediate RF downconversion. The accuracy of the generalized method is assessed by comparison of its bit error probability (BEP) estimates with the estimates obtained from Monte Carlo (MC) simulation.…”

“…1 shows the model of the optically preamplified directdetection receiver followed by the OFDM electrical receiver with I/Q demodulation at the RF frequency f RF . This model is a generalization of the baseband OFDM optical receiver described in [3]. The optical receiver model includes an optical amplifier, an optical filter, a PIN photodetector and an electrical filter [4].…”