Performance of optimal dual transmit antenna diversity system for unknown, correlated Rayleigh fading channels

As is well known, an effective method for overcoming fading in wireless communication systems is to employ diversity techniques. Recently, there has been considerable interest in transmit antenna diversity due to some of the advantages it affords over other diversity methods. This thesis investigates a new method to obtain dual diversity using two transmit antennas and one receive antenna, space-time block coding. Previous investigations of this problem have assumed that there is no correlation between the two fading channels and that the fading experienced over each independent channel is known at the receiver. In this thesis, it is assumed that the fading channels may be correlated and that the channel is known only statistically. The mathematically optimal receiver is derived for this case assuming non-coherent orthogonal digital modulation is used and assuming the channel exhibits frequency non-selective, slow Rayleigh fading. The performance of the optimal receiver for dual transmit antenna diversity over the unknown channel is obtained by finding relatively tight analytical bounds on the probability of bit error. The performance of the system is compared to existing results for transmit antenna diversity over a known channel and for receive antenna diversity over unknown and known channels. It is found that the bit error rate of the system is comparable to that of a dual receive antenna diversity system using non-coherent digital modulation over an unknown channel.