A Simple Performance Approximation of General-Order Rectangular QAM With MRC in Nakagami- $m$ Fading Channels

The sampling property of the delta impulse function is applied to various Q-function approximations to obtain the probability of error in Nakagami- m fading channels. It is shown that the sampling bit error probability (BEP) exhibits reliable behavior, regardless of the Q-function approximation form. The result is extended to general-order rectangular quadrature amplitude modulation (QAM) with maximal-ratio combining (MRC) to quantify the average symbol error probability (SEP). The proposed approximation presents the SEP in a simple closed form and eliminates the hypergeometric function in the solution. The proposed sampling SEP is accurate and applicable for an arbitrary real-valued fading parameter.