Introduction Frequency-selective fading is a dominant impairment in mobile communications Fading reduces receive signal-to-noise ratio and degrades the bit-error-rate(BER) Frequency selectivity of the channel, i.e., delay spread, induces inter-symbol interference(ISi) To combat frequency-selective fading, diversity techniques must be resilient to ISI Transmitter diversity techniques are attractive especially for portable receivers where current drain and physical size are important constraints Georgia Institute of Technology Center for Signal and Image ProcessingGeorgia Institute of Technology Center for Signal and Image Processing Introduction • Frequency-selective fading is a dominant impairment in mobile communications. – Fading reduces receive signal-to-noise ratio and degrades the bit-error-rate (BER). – Frequency selectivity of the channel, i.e., delay spread, induces inter-symbol interference (ISI). • To combat frequency-selective fading, diversity techniques must be resilient to ISI. • Transmitter diversity techniques are attractive, especially for portable receivers where current drain and physical size are important constraints