A clever combination of transmit symbols to reduce flat fading effect

For the case of single-antenna wireless communication systems, we propose a clever combination of transmit symbols, to reduce fading in relatively fast-fading channels. The proposed technique, called delayed two-streams division (D2SD), can be regarded as inserting a delay between two nonequal power chips of a two-user code division multiple access (CDMA) system. At receiver, a very simple maximum-likelihood detection based scheme is used to "equalize" the symbol combination made at transmitter. Our results show a considerable improvement in the performances of the receiver, that is obtained with no increase in the transmit power and implies no loss in the spectral efficiency.