Transmission and reception in a hostile interference environment

摘要

PCT No. PCT/GB91/00513 Sec. 371 Date Oct. 29, 1992 Sec. 102(e) Date Oct. 29, 1992 PCT Filed Apr. 2, 1991 PCT Pub. No. WO91/15925 PCT Pub. Date Oct. 17, 1991.A low power OFDM signal may be transmitted in an environment where it is subject to interference from other transmissions, e.g. broadcast television services. In a receiver interference is reduced by ignoring information modulating OFDM carriers at the frequencies corresponding to the carriers of the interfering transmissions; adjacent channel interference is reduced by ignoring data on OFDM carriers at the band edges and interference from third order intermodulation products is reduced by the ignoring OFDM carriers affected. Image channel interference is reduced by using an intermediate frequency for a first mixing process in the receiver such that the image channel interference affects OFDM carriers at frequencies which are already being ignored by the receiver. Preferably no data is modulated onto OFDM carriers which are to be ignored by the receiver. Preferably the modulation of the OFDM carriers is arranged so as to produce a real baseband representation of the OFDM signal.