Asymptotic BEP and SEP of Differential EGC in Correlated Ricean Fading and Non-Gaussian Noise

In this paper, we study the asymptotic behavior of the bit-error probability (BEP) and symbol-error probability (SEP) of differential M-ary phase-shift keying with differential equal gain combining (DEGC) in correlated Ricean fading and non-Gaussian noise, which in our definition also includes interference. We derive simple and easy-to-evaluate asymptotic BEP and SEP expressions which show that at high signal- to-noise ratios (SNRs) the performance of DEGC depends on certain moments of the noise and interference impairing the transmission. We provide closed-form expressions for these moments for practically important types of noise such as Gaussian noise, Gaussian mixture noise, and correlated co-channel interference. In addition, we show that the performance loss of DEGC compared to coherent maximum ratio combining (MRC) is always 3 dB independent of the type of noise if only one diversity branch is available but strongly depends on the type of noise if multiple diversity branches are combined.