An Improved Quasi- Orthogonal Space-Time Block Codes for Diversity Reception in Wireless Communication

Quasi orthogonal space time block codes have been proposed to achieve higher symbol transmission rates for more than 2 transmit antennas at the expense of losing the diversity gain. In this paper we propose a method to improve its transmit diversity with one bit feedback. This method useful for extend any space-time code constructed for 4 transmit antennas to M receive antennas. An improvement in transmit diversity is achieved by multiplying each QOSTBC code word with appropriate phase factor which depend on the channel information. Jafarkhani’s Quasi Orthogonal Space Time Block Codes as well as its optimal constellation rotated scheme are extended and analyzed.