Jerrod Langston

Agile micro- and millimeter-wave communication using photonic frequency conversion

Broadband wireless transmission with tunable 5-40GHz carrier is demonstrated using photonic frequency conversion. The agile tuner allows ~4 GHz of instantaneous bandwidth for both up- and down-conversion paths, without banding or channelization.

Autonomous receivers for complex format identification and demodulation

We demonstrate a new universal DSP receiver architecture for ground-based optical communications that autonomously identifies and decode TDHMFs in addition to conventional formats. The combination of a flexible and modular architecture with proper statistical tools has enabled successful validation of autonomous identification and demodulation, suggesting that these methods are extensible to any format including those not yet examined. Similar architectural concepts can be generalized to wireless communications, thus spanning the whole communication range of the avionics ecosystem.

DAC Enabled Frequency Domain Pre-shaper Design for Nyquist Signaling

A blind DAC enabled frequency domain pre-shaper design is demonstrated for combating the narrowband filtering effects for 31.5Gbaud Nyquist PM-8QAM and PM-16QAM signals. Experimental results demonstrate an overall performance improvement.

Optical signal reconstruction using transmit-side DSP

We present a method for linear impairment emulation of optical signals using transmit-side DSP to enable the generation of realistic stressed waveforms and thus the testing of receivers without the network. We experimentally demonstrate CD and phase noise emulation.

Cyclostationarity-based classification of OFDM waveforms over photonic-assisted wireless links

Orthogonal frequency-division multiplexing (OFDM) is employed extensively in wireless communication networks to reduce receiver side computational complexity, improve tolerance to fading, improve spectral efficiency, and ease synchronization; it is also being considered for 5G systems. Traditionally, communication links operate with shared knowledge of modulation parameters, here we focus on developing a smart receiver that can identify and demodulate OFDM signals without a priori knowledge. Motivation for autonomous receivers lies in network monitoring and diagnostics and recovery from failures. Photonic-assisted wireless links exploit the low-loss characteristics of optical fiber and high-bandwidth photonic components to offer multi-octave, flexible signal generation and transport with large available instantaneous bandwidths. These characteristics synergize well with the flexibility of OFDM waveform design.

Photonic frequency downconversion link theory and simulation

A method for evaluating the performance of photonic downconversion links was advanced from a theoretical and simulation stand-point. Digital post-processing linearization was investigated for a practical link with simple inputs, but will be extended to include wider bandwidth signals.