An impulse radio communications system using one or more subcarriers to communicate information from an impulse radio transmitter to an impulse radio receiver. The impulse radio communication system is an ultrawide-band time domain system. The use of subcarriers provides impulse radio...http://www.google.com.hk/patents/US5677927?utm_source=gb-gplus-share專利 US5677927 - Ultrawide-band communication system and method
