5G RAN, like LTE, depends strongly on PRACH preamble successful detection for high Accessibility Success Rate. 5G NR network planning and optimizing should always focus on Uplink interference and Uplink SINR, since PRACH preamble detection probability is a function of received signal strength and interference, This documents provides a useful short overview level of RACH procedures, emphasizing the preamble detection probability vs. SINR