REDUCTION OF PEAK TO AVERAGE POWER RATIO

摘要

The present invention is related to methods and apparatus that can advantageously reduce a peak to average voltage and power signal level exhibited by single or by multicarrier multibearer waveforms. Embodiments of the invention further advantageously can manipulate the statistics of the waveform without expanding the spectral bandwidth of the allocated channels. One embodiment of the invention includes a preconditioning circuit 310, which selectively removes relatively high signal peaks from an input symbol stream 302. An output of the preconditioning circuit is pulse-shaped and upconverted. Multiple input symbol streams can be similarly preconditioned, pulse-shaped, and upconverted. The upconverted signals are combined to a composite signal by a combiner 350 and are also provided as an input to a post-conditioning pulse generator 348. The post-conditioning pulse generator 348 generates at least one bandlimited pulse that to the combined upconverted signals to reduce a signal peak that can be induced by a pulse-shaping filter 316. Embodiments of the invention can be applied to either multiple carrier or single carrier systems to constrain an output signal within predetermined peak to average bounds. Advantageously, the techniques can be used to enhance the utilization of existing multicarrier RF transmitters, including those found in third generation cellular base stations. However, the peak to average power level managing techniques disclosed herein can apply to any band-limited communication system and any type of modulation. The techniques can apply to multiple signals and can apply to a wide variety of modulation schemes or combinations thereof.