On the Theoretical Limits of the Power Efficiency of Photonically Generated IR-UWB Waveforms

The design and photonic generation of power-efficient impulse radio ultra-wideband (IR-UWB) waveforms is a challenging step in the design and development of IR-UWB over fiber (IR-UWBoF) systems with combined optical and wireless transmission. In this paper, the definition of the spectral power efficiency (SPE) and its associated optimization problem are reformulated. Based on this reformulation, a theoretical upper bound for the SPE is derived and applied to two of the most common types of photonically generated IR-UWB waveforms. Accurate closed-form analytical expressions for the SPE upper bounds of these two waveform types are obtained and optimized. The analytical framework presented in this paper can be extended and applied to other waveform types. Simulation results show excellent agreement with the analytically obtained expressions. Accordingly, these analytical expressions can be used as reliable guidelines for precise and efficient design of practical IR-UWBoF systems that guarantee optimal design, generation, and distribution of IR-UWB waveforms.