The use of unmanned aerial vehicle, as Aerial Base Stations (ABSs) has received high attention in academia and industry for supporting the communication traffic growth. In this article, we focus on obtaining the optimal altitude of an ABS using two criteria - maximum cell coverage area and minimum Symbol Error Rate (SER), implemented on a probabilistic Air-to-Ground (A2G) channel model, developed for low altitude aerial platforms via simulations on a commercial ray tracing software, for various scenarios such as Urban High Rise, Urban and Suburban. We present a system model based on Generalized Frequency Division Multiplexing (GFDM) used for SER analysis in a time-frequency grid compatible with Long Term Evolution (LTE) by implementing parameters for low latency communication of Physical Layer (PHY). Also, we provide the probability distributions of the received power of the ground users and power delay profile at optimal ABS altitude. We demonstrate the variation of optimal altitude with cell area. We further analyze the impact of “Better than Nyquist” pulses on the GFDM system and evaluate SER performance. From the proposed results, significant improvement is demonstrated compared to Nyquist pulses.