Constant Envelope Orthogonal Frequency Division Research Articles

Dual-Stream Transceiver Structure With Single Antenna for Phase-Modulated OFDM

Constant envelope orthogonal frequency-division multiplexing (OFDM) can achieve 0-dB peak-to-average power ratio (PAPR) by transforming the OFDM signal to a constant envelope signal. However, its spectral efficiency is less than half of the OFDM. In this letter, a dual-stream transceiver structure with single antenna is proposed to increase the spectral efficiency. At the transmitter, the structure based on phase shifting is proposed to transmit two data streams simultaneously. At the receiver, the joint demodulation structure based on Taylor series expansion is proposed to separate the data streams and eliminate the need for a phase demodulator. The mathematical analysis reveals that the statistical PAPR of the baseband signal is 3 dB. The bit error rate performance is evaluated with additive white Gaussian noise channel and multipath fading channel under the condition of ideal power amplifier and solid-state power amplifier. Simulation results show that the proposed structure can improve the spectral efficiency and is robust against multipath fading.

Transmission of CE-OFDM Signals Over MMF Links Using Directly Modulated 850-nm VCSELs

We report the experimental transmission of constant-envelope orthogonal frequency division multiplexing (CE-OFDM) signals over short-reach multimode fiber links. Error-free transmission of 2.2 Gb/s over a 300-m OM-3 fiber link, using a directly modulated 850-nm vertical-cavity surface emitting laser and direct detection, is achieved. The results confirm the CE-OFDM modulation format as a low peak-to-average power ratio alternative for low-cost data-center interconnects.

Experimental validation of a constant-envelope OFDM system for optical direct-detection

In this paper, we experimentally investigate a peak-to-average power ratio (PAPR) reduction technique based on a constant envelope orthogonal frequency division multiplexing (CE-OFDM) approach in direct-detection optical OFDM (DDO-OFDM) systems. In comparison to conventional DDO-OFDM, our results show a 6.37dB performance gain in terms of error vector magnitude (EVM) with a 5Gb/s DDO-CE-OFDM transmission system over 40km of uncompensated standard single-mode fiber (SSMF) at an optical injection power of 5dBm.

A PAPR Reduction Technique Based on a Constant Envelope OFDM Approach for Fiber Nonlinearity Mitigation in Optical Direct-Detection Systems

In this paper, we propose a new peak-to-average power ratio reduction technique based on a constant envelope orthogonal frequency division multiplexing (CE-OFDM) approach to mitigate fiber induced nonlinearities in direct-detection optical OFDM (DDO-OFDM) systems. Simulation results show that the proposed 10 Gbps DDO-CE-OFDM system using 16-quadrature amplitude modulation (16-QAM), 2.66 GHz signal bandwidth, and different values of electrical phase modulation index outperforms DDO-OFDM systems as it increases the fiber nonlinearity tolerance in fiber links without optical dispersion compensation. The bit error rate of the proposed transmission scheme is decreased by a factor of 1000 if compared to conventional DDO-OFDM systems, for 10 dBm of optical input power and considering a span of 960 km of standard single-mode fiber.