The disclosure relates to a new Alamouti-based mapping scheme for use in a real field FBMC modulation system which can reduce FBMC-intrinsic interference and allows approaching optimal performance. The Alamouti-based mapping scheme proposed herein can be used for implementing space-time or space-frequency block codes (STBC/SFBC) codes. The proposed Alamouti-based mapping scheme suggests specific patterns to negate/invert signs of the modulation symbols of Alamouti pairs in the Alamouti mapping. By using these special patterns of sign negation, the FBMC-intrinsic interference can be reduced significantly so that it may become possible to use conventional Alamouti demapping/decoding procedures on the receiving side with an overall acceptable performance in real life systems.