A unified framework for reference-based ultra-wideband signaling

One application area of significant interest for ultra-wideband (UWB) technology is in localization and low-to-moderate data rate communication. Due to implementation complexity concerns, many recently proposed systems have been based around transmitted reference (TR) or pulse-position modulation (PPM) architectures. In response to the difficulty in implementing the delay line in small integrated receivers for the original TR system, frequency-shifted reference (FSR) UWB systems were developed, which in turn motivated recent code-shift (CS)-UWB and code-multiplexed (CM)-UWB systems. Here, we update our recent framework for reference-based UWB systems to encompass these recently-proposed systems and use recent experience on a UWB commercialization project for radio frequency identification (RFID) applications to provide perspective on the evaluation of systems within the framework. Performance is considered under both average and peak energy constraints. Under the latter constraint, it is important to consider methods of peak mitigation, so an extension of the tone reservation method employed in orthogonal frequency division multiplexing (OFDM) systems is applied to systems within the framework, often without the cost in bandwidth efficiency observed in standard OFDM systems. Differences across the class, as measured in terms of peak power, can often be larger than those measured versus average power. Operating conditions where such is significant (or not) are reviewed.