Performance Analysis of Narrow-Band IoT Coverage Enhancement Based on Repetition and Retransmission

This paper established a preamble detection probability model based on random geometry and a collision probability model based on multi-band and multi-channel slotted ALOHA for the randomly deployed narrow band Internet of things (NB-IoT) terminals and base stations. The detection probability of the base station for the preamble and the competing success probability of terminal to channel are analyzed. The random access success rate and average access delay of the terminal are derived. The simulation results show that the detection probability increases with the repetition times. And the random access success rate increases with the increase of retransmission times and the available channel numbers.