A high speed modem system which utilizes multiple carriers to successively transmit frames containing data such that the frames are transmitted so that the level of the signal is minimized, and is preferably zero, at the borders between individual frames thus, reducing or eliminating interframe discontinuities...http://www.google.de/patents/US5128964?utm_source=gb-gplus-sharePatent US5128964 - Modulation method and apparatus for multicarrier data transmission
