Bit error probability for orthogonal space time block codes with differential detection

Abstract

The bit error probability (BEP) of space time block codes (STBC) based on Alamouti's scheme with differential encoding and decoding and ultilising 2 b-ary phase shift keying (2 b-PSK) modulation is studied and close form analytical results are obtained. The channel model is that of a frequency non-selective and slow Rayleigh fading channel. While all existing analyses assume no fading fluctuations, these are considered in our analysis here. For the case in which the fading process remains constant within any code block interval but which fluctuates from one code block interval to the next, exact closed-form expressions for the BEP of binary and quadrupture PSK are derived. An approximate result is obtained for 8PSK. For the case in which the fading process fluctuates from one symbol interval to the next, but which remain constant within the symbol interval, upper and lower bounds are obtained for the BEP and a simple and yet accurate approximation to the BEP is developed. The analysis is applicable to any number of receive antennas.