A space time labelling technique for wireless communication systems is provided. A transmitter for implementing the technique includes a first bit mapper and a second bit mapper which is different to the first bit mapper and first and second transmitters. A processor is connected to the first and second mappers and the first and second transmitters and controls these to receive two bit streams and simultaneously feed these into the first mapper and the second mapper. The first mapper maps these into first and second mapped bit streams and the second mapper maps these into third and fourth mapped bit streams which are different from the first and second mapper bit streams. The first mapped bit stream is transmitted in a first time slot via the first transmitter and the second mapped bit stream is transmitted in the first time slot via the second transmitter. The third mapped bit stream is transmitted in a second time slot via the second transmitter and finally the fourth mapped bit stream is transmitted in a second time slot via the first transmitter.