A general result is derived for the bit error rate (BER) of differenti
al quadrature phase shift keying (DQPSK) for reception in slow fading
and additive white Gaussian noise (AWGN). Fading models include Raylei
gh, Rician, Nakagami and shadowed Rician, which describe a wide range
of fading conditions encountered in mobile communications. Easily comp
utable, the result is potentially useful in evaluating the BER of such
systems.