BER of π/4-DQPSK with multichannel reception: Some series solutions

We present bit error rate (BER) expressions of pi/4 shifted differential quadrature phase shift keying (pi/4-DQPSK) with single and multi-channel reception over generalized fading channels in presence of additive white Gaussian noise (AWGN). Slow flat small scale statistical fading models, namely Rayleigh, Rician, Nakagami-m and Hoyt fading has been assumed. Moreover, to improve the link quality receiver antenna space diversity is considered where multiple independent and identically distributed (i.i.d.) as well as uncorrelated signal replicas are combined before successive demodulation. The proposed linear predetection combiner follows optimum maximal ratio combining (MRC) algorithm. Obtained error expressions, computed through probability density function (pdf) based approach, consist of finite or, infinite series with fast convergence rate. The series solutions get rid of numerical integration and realize a trade-off between precision and complexity by choosing the number of terms while calculating BER. BER values are plotted against signal to noise ratio (SNR) per bit per channel for each model for different values of diversity order L with varying fading parameters (K, q, and m).