Abstract
This paper proposes new accurate approximations for average symbol error probability (ASEP) of a communication system employing either M-phase-shift keying (PSK) or differential quaternary PSK (DQPSK) modulation schemes, with Gray coding over κ-μ shadowed fading channel. Firstly, new accurate approximations of symbol error probability (SEP) of both modulation schemes are derived over additive white Gaussian noise (AWGN) channel. Leveraging the trapezoidal integral method, a tight SEP's approximation for M-PSK modulation is presented, while new upper and lower bounds for Marcum $Q$-function of the first order (MQF), and subsequently those for SEP under DQPSK scheme, are proposed. Next, these bounds are linearly combined to propose a highly accurate SEP's approximation. The key idea manifested in the decrease property of modified Bessel function $I_{v}$, strongly related with MQF, with its argument v. Finally, theses approximations are used to tackle ASEP's approximation under $\kappa-\mu$ shadowed fading. Numerical results show the accuracy of the presented approximations compared to the exact ones.
Threshold Based Signal Detection and the Average Symbol Error Probability for Downlink NOMA Systems With M-ary QAM
