This book presents the design and bit error rate (BER) performance of a Differentially Quadrature phase shift keying (DQPSK) signals over additive white Gaussian channel (AWGN) with L number of diversity branches. The performance of a DQPSK signals is also studied with post detection equal Gain combining in additive white Gaussian noise and slow frequency- non selective identical and non identical weibull fading channels, in which diversity branch can have unequal signal-to-noise ratios (SNRs) as... Mehr