Abstract: A method and system shapes a spectrum of an impulse radio signal, such as an UWB signal. First, basis pulses at various frequencies and pseudo-random delays are generated. The generated set of basis pulses are then weighted and delayed, and combined linearly to conform the spectrum of the transmitted basis pulses to a spectral mask. The spectral mask can be predetermined, or the conforming can be adaptive. Furthermore, the basis pulses can be frequency-shifted before the combining.

Abstract: A method for antenna subset selection by joint processing in RF and baseband in a multi-antenna systems. Lt input data streams are generated in a transmitter for either diversity transmission or multiplexing transmission. These streams are modulated to RF signals. These signals are switched to the t branches associated with the t transmit antennas, and a phase-shift transformation is applied to the RF signals by a t×t matrix multiplication operator ?1, whose output are t?Lt RF signals. These signals are transmitted over a channel by t antennas. The transmitted signals are received by r antennas in a receiver. A phase-shift transformation is applied to the r RF signals by a r×r matrix multiplication operator ?2. Lr branches of these phase shifted streams are demodulated and further processed in baseband to recover the input data streams.